Critical Reviews in Oncology/Hematology 74 (2010) 40–60

The role of immunity in elderly cancer Lucia Malaguarnera b , Erika Cristaldi a , Mariano Malaguarnera a,∗ a

Department of Senescence, Urological and Neurological Sciences, University of Catania, Italy b Department of Biomedical Sciences, University of Catania, Italy Accepted 5 June 2009

Contents 1. 2.

3. 4.

5. 6. 7. 8. 9.

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alterations leading to immunosenescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1. Primary lymphoid organs involution and immunosenescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Haematopoietic stem cells (HSCs) in the aged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3. B cells in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The immune response against tumors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The acting company of the immunosenescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. T cells in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1. T regulatory cells (Treg cells) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.2. T lymphocytes bearing the ␥␦ TCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Natural killer cells in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Antigen-presenting cells in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4. Dendritic cells in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5. Macrophages in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6. Polymorphonuclear leukocytes in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Genetic alterations in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tumor-induced immunosuppression in the elderly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inflammaging cytokines and tumorigenesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemokines and tumorigenesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reviewers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Biographies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

41 41 41 42 43 44 45 45 46 46 47 48 49 49 50 50 52 52 54 55 55 55 60

Abstract The increased incidence of malignancies in elderly patients living in industrialized countries has led to both identify the causes that alter the normal homeostatic balance in elderly and designate the specific treatments. The progressive decline of the immune system (immunosenescence) involving cellular and molecular alterations impact both innate and adaptive immunity. The immunosenescence leads to increased incidence of infectious diseases morbidity and mortality as well as heightened rates of other immune disorders such as autoimmunity, cancer, and inflammatory conditions. Here, we summarize the knowledge on the major changes in the immune system associated with aging in primary lymphoid organs as well as a description of molecular mechanisms, and the impact on cancer development. © 2009 Elsevier Ireland Ltd. All rights reserved. Keywords: Cytokines; Chemokines; Immunosenescence; Tumorigenesis; Ageing; Lymphocytes; Haematopoietic stem cells

∗

Corresponding author at: Department of Senescence, Urological and Neurological Sciences, Azienda Ospedaliera Cannizzaro, via Messina 829, 95124 Catania, Italy. Tel.: +39 095 7262008; fax: +39 095 7262011. E-mail addresses: [email protected] (E. Cristaldi), [email protected] (M. Malaguarnera). 1040-8428/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.critrevonc.2009.06.002

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1. Introduction A considerable body of data suggests that the incidence of cancer increases exponentially with age [1]. Aging is a complex physiological process that involves a number of biochemical reactions, with molecular changes that are manifested in single cells as well as in the whole organism. The epidemiological studies indicate that about 55% of tumors have been detected in a population over 65 years. The most frequent sites in men over 65 years are represented by lung, colon, rectum, prostate and bladder [1], whereas the women show higher incidence of tumors in breast, lung, colon-rectum, bladder and pancreas as well as non-Hodgkin lymphoma [1]. The association between cancer and age can be explained by a more prolonged exposure to carcinogens in older individuals and an increasingly favourable milieu for the induction of neoplasms in senescent cells [2], as complex biological phenomena, susceptibility to cancer and its age-dependent increase is thought to include mixed genetic and environmental components [3]. These potential causes lead older humans to accumulate effects of mutational load, increased epigenetic gene silencing, telomere dysfunction, limitless replicative potential, altered stromal milieu, evading apoptosis, sustained angiogenesis, tissue invasion and metastasis [4]. These changes allow transformed cells to acquire a selective advantage of proliferating and growing. Therefore, aging reflects the sum of all changes that occur in living organisms with the passage of time that lead to functional impairment and increased pathologies. The progressive deterioration of the immune system with age [5] seems to be of fundamental importance on the increased incidence of cancer in the elderly, because cancer has an important inflammatory component. The microenvironment of a developing tumor is infiltrated by numerous host cells, such as inflammatory cells, endothelial cells and fibroblasts. The interaction between genetically “initiated” cells and host cells is inevitable for carcinogenesis. Interestingly, once tumors arise, they and their products are recognized by the adaptive immune system and rejected. Nevertheless, the tumor often coevolves with immunity, like a parasite, as demonstrated by findings that inflammation enhances tumorigenicity. Tumors coexist with immune defence systems over extended periods and interact chronically with T cells. A process called “immunesurveillance” is used by the host to protect itself by carcinogenesis and to maintain cellular homeostasis. Both innate and adaptive immunity are involved in the first attack to nascent transformed cells, trying to eliminate them. The effect of this phenomenon is potentially similar to other situations of chronic antigenic stress, particularly maintained by lifelong persistent viral infections. At the moment the role of the immunosenescence on cancer incidence is an extremely debated argument. It has been suggested that the immunosenescence is not an inevitable and progressive decline of all immune functions, but rather the result of a continuous remodelling process in which several functions are reduced, others increased, while others remain

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unchanged [6]. Studies of the immune system of centenarians, spotlighted that one of the main factors of longevity may be represented by well functioning immune system which allows the prevention of the main age-related pathologies including cancer, as death from cancer may decline at very old age. In this article we will discuss how the immunosenescence can be involved as an age-related risk in cancer incidence. Elucidation of the causes of increasing cancer incidence with ageing can help to design a strategy for primary cancer prevention.

2. Alterations leading to immunosenescence 2.1. Primary lymphoid organs involution and immunosenescence Data obtained in the context of cross-sectional studies on healthy subjects, from young people to centenarians [7] have reported the involution of the primary lymphoid organs and defects in the production of early lymphoid precursors severely impact on the immune system. A remarkable example is the contribution of the thymus in restoring the periphery of freshly generated T lymphocytes, which decays rapidly over age [7] (Fig. 1). Despite a massive involution of the thymus during the first decades of life, the decline of CD4+ and CD8+ T cell number is relatively insignificant, and the discrepancy between thymic mass and the number of peripheral T cells is particularly evident in the oldest old [7]. The current literature suggests that a substantial amount of T cells is maintained into late middle-age until the extreme limits of the human life-span, probably as a result of different mechanisms, such as extra-thymic T cells production, and the peripheral expansion of long-lived, antigen-experienced T cells [8]. Without a doubt, an age-dependent decrease of antigen-not experienced (naïve) CD95− CD45RA+ CD62L+ cell number, particularly within CD8+ T cells pool arises in humans, as a consequence and/or possibly as a compensatory mechanism, suggesting that the immune system in aged has a lowered capacity to neutralize antigens not previously encountered [9]. These alterations are paralleled by an age-dependent increase of CD4+ and CD8+ CD95+ antigenexperienced T cells. In particular, an impressive expansion of effector/cytotoxic CD28− T cells is observed throughout life [10]. It is conceivable that the alterations observed in total lymphocytes are mainly attributable to the change of expression of CD95 (APO1/Fas) on CD4+ lymphocytes, whereas the CD8+ CD95+ population rose steadily throughout the entire age range (Fig. 1). It has been demonstrated that the increase of CD95 on both CD45R0+ and CD45R0− T lymphocytes and the increase of CD95+ /CD28+ T cells concomitant with a decline of the number of CD28+ T lymphocytes [11]. As consequence, the enhanced expression of CD95 on lymphocytes of old subjects leads to an enhanced proneness to undergo apoptosis. So it has been hypothesized

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that although there is a large amount of memory-preactivated lymphocytes in the elderly, the inability to evoke a strong secondary response to vaccines may be attributable to enhanced apoptosis [12]. The activation of T cells requires costimulatory signals, and it is known that CD28 represents an important costimulatory molecule, the expression of which decreases with age [13]. CD28+ T cells decrease mainly in the last decades of life. In addition, the enhancement of expression of CD95 on CD28+ lymphocytes with age may be indicative of an involvement of CD95 in the age-related depletion of CD28+ T lymphocytes. 2.2. Haematopoietic stem cells (HSCs) in the aged Several deficits of the immunosenescence begin with stem cells. HSC possess the ability to differentiate into different blood-borne cells, coupled with the capacity of self-renewal to prevent clonal exhaustion. In the elderly, a reduction on the

whole capacity for renewal of stem cells has been detected [14]. The proliferative activity of bone marrow reaches the peak in middle age and then progressively decreases. It has been reported that, with aging, there is a reduction in commitment to lymphopoiesis [15] and a reduction in the ability of marrow stroma to support lymphopoiesis [15]. In the extreme age reductions in marrow cellularity [16], conceivably is associated with increased apoptosis [17]. Consistent with these evidences it has been observed that CD34 stem cells mobilize less effectively in the elderly when compared to younger donors [14]. This could derive from their inability to adhere within the bone marrow stromal environment, leading to a reduction of the homing potential of old HSCs [18] (Fig. 1). The aged HSCs compromise all downstream events that depend on their integrity, including production of immune cells and subsequent immune responsiveness [19]. Evidence for age-associated alterations in the ability of HSCs to recon-

Fig. 1. The consequences of ageing on the various components of the immune system. The thymus involution in elderly people can results in a higher prevalence of CD8+CD95+ antigen-experienced T cells. In particular, an impressive expansion of effector/cytotoxic CD28− T cells is observed throughout life. These alterations are paralleled by an age-dependent decrease of antigen-not experienced (naïve) CD95− CD45RA+CD62L+ cell number, particularly within CD8+ T cells pool arises. The functional decline of haematopoietic stem–cell functions, consisting in a decreased capacity to renewal and in a lower homing potential, affects both the lymphoid and myeloid lineage. The aged HSC compromises all downstream events that depend on their integrity, including production of immune cells and subsequent immune responsiveness. HSC: haematopoietic stem cell; CLP: common lymphoid progenitor; ROS: reactive oxygen species; DC: dendritic cell; NK: natural killer; IFN: interferon; TCR: T cell receptor; Th1/Th2: T helper 1/T helper 2; VEGF: vessel endothelial growth factor; IL: interleukin; Treg: T regulatory cells.

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stitute the haematopoietic system derives from findings that purified HSCs from old mice showed less activity on a per-cell basis and tended to generate more myeloid cells such as macrophage, than lymphocytes. Expression profiling of young and old HSCs revealed that genes mediating lymphoid function were down-regulated, whereas myeloidspecification genes with age were up-regulated. These changes suggest epigenetic mechanisms contribute to functional decline of HSC. There is also a gradual decline in the ability of murine HSCs to progress through the various stages of B-cell-differentiation [20]. This reflects, in part, the micro-environmental changes involving altered production of interleukin-7 (IL-7) by stromal cells as they age [21] (Fig. 1). B cells must also compete for the cytokine BLys (or B-cell activating factor (BAFF)), the receptor levels of which influence survival. Declining B-cell production in aged animals results in selective accumulation of marginal zone and memory B cells at the expense of the follicular pool of B cells. The follicular pool is responsible for producing protective immune responses to newly encountered pathogens. The declining stem–cell function and the resultant decline of the follicular B-cell compartment lead to enhanced infectious disease-related morbidity with ageing [22]. Thus it is evident that there are significant genetic components that regulate stem cell ageing [23]. For instance, studies in C57BL/6 mice revealed an increase in the number of HSC in aged mice [24]. In contrast, the number of HSC in DBA mice markedly decreased with age. Recently, gene array data have showed that the transcript from old HSC reflected a reduced capacity to differentiate into the lymphoid lineage, while exhibiting a gene expression profile that reflected an increased myeloid potential [25]. Furthermore, the expression of the cell-cycle inhibitor p16 INKa appeared to increase with age in HSC and evidence suggests that this age-dependent increase contributes to the reduced potential repopulation of old HSC [26]. Overall these studies demonstrate that ageing process of HSC is a cell-intrinsic phenomenon which induces in these cells an altered setting of hematopoietic differentiation and of reconstitution ability. 2.3. B cells in the elderly B cells play a critical role in the anti-tumor humoral responses by differentiating into antibody-secreting plasma cells. The produced antibodies (IgM and IgG) destroy tumor cells through either activation of complement or interaction with lytic cells which possess surface receptors for the Fc portion of the antibody-dependent cell mediated cytotoxicity (ADCC). Humoral immunity in the elderly is compromised as the result both of the decreased production of longterm immunoglobulin-producing B lymphocytes dependent to intrinsic and micro-environmental defects, and of the loss of immunoglobulin diversity and affinity caused by the disruption of germinal centre formation [27]. The data concerning the B lymphocytes show that both quantitative and qualitative alterations affect these cells

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Table 1 B lymphocytes in elderly. Age-related alterations

Functional effects

↓ production of Ab with high affinity and specificity ↑ production of Ab with low affinity ↑ production of autoantibody

Lower efficiency of humoral immune response against external antigens Higher incidence of MGUS Higher frequency of autoimmune disorders

Ab: antibody; MGUS: monoclonal gammopathies of uncertain significance.

(Table 1; Fig. 1). In the first case, the number of B cells secreting immunoglobulins or antigen-specific immunoglobulins is decreased. Qualitative changes include alterations in the activity of B-cell subsets as well as shifts in the antibody repertoire with respect to the specificity, isotype and idiotype [28]. Paradoxically, while the antibody response to foreign antigens is lower in old individuals compared to the youngest, the number of B cells secreting antibodies is enhanced [29]. This paradox can be explained by the increased life-span and self-renewal of peripheral B cells in old mice, so the number but not the diversity of the B cell repertoire is maintained. This restricted diversity of the B cell repertoire may be associated with the appearance of B cell clonal expansions that can be precursors of late life B cell lymphomas [30]. Furthermore, some studies in murine models have shown that the antibodies produced by old mice have a lower affinity for their targets and so, are ineffective in preventing infection [31,32]. Despite the significant decline in B-cell production in the aged mice, peripheral B-cells number remains relatively constant. One reason might be that the peripheral B-cell pool is already ‘saturated’, in a manner that is similar to what happens in T-cell homeostasis in the old [20]. However, another possible explanation is that peripheral B cells in the mouse reflect a decreased B-cell generation and an increase in peripheral B-cell longevity [33]. Furthermore, it has been reported that B cells from aged donors show a decreased expansion in response to antigens [34], whereas, the ability of aged B cells to differentiate into high-affinity, isotype-switched, antibody secreting cells is well preserved [28]. As a consequence of altered composition of B cell pool, it has been reported a shorter duration of humoral response in elderly than in the young. Recent studies have demonstrated a decline in B lymphopoiesis in aged mice which reflects the loss of very early B-lineage precursors [35] (Fig. 1). The decline in frequencies of pre-B cells it was presumed to be principally the consequence of the diminished capacity of Pro-B cells to differentiate. HSCs in the bone marrow give rise to early B cells from common lymphocyte precursors, which become Pro-B cells in the bone marrow by immunoglobulin heavy chain gene rearrangements and subsequently differentiate into PreB cells, which then migrate to the periphery [36]. Transition to Pro-B cell and Pre-B cell stages are dependent upon the activity of recombination activating gene 1 (RAG1) and RAG2 [36]. Several lines of evidence show that Pro-B cells in old mice are impaired in their capacity to rearrange the D to J

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gene segments and the V to DJ gene segments. Several studies have also underlined the loss of RAG mRNA in total bone marrow preparations from old mice [37]. Interesting studies using reciprocal bone marrow chimeras have led to hypothesize that RAG expression in Pro-B cells is controlled by the microenvironment itself rather than being an intrinsic defect of senescent B-cell progenitors [37]. Additional evidence supporting this hypothesis has come from stromal cell cultures, because cultures from old individuals are less efficient in supporting B-cell proliferation than those from young counterparts [15]. Nevertheless, other reports have suggested defects in aged B-cell precursor transcription factors. E2A and Pax-5 are crucial to B lymphopoiesis because they accompany differentiation, proliferation and survival of early B cells following interleukin-7 (IL-7) receptor interaction [38]. The reduced expression of the downstream products of E2A (E47 and E12) and Pax-5 (B-cell-specific activator protein; BSAP) have also been shown to accompany old age in Pro-B cells [38]. Many other intrinsic B-cell defects have also been reported in aged mice and humans, including reduction of co-stimulatory molecules [39], defects in B-cell receptor signaling and lower titer and affinity of produced immunoglobulins which make them less protective [40]. These effects may be due to intrinsic defects of B cells, such as decreased expression of co-stimulatory molecules as B7 (CD 86) and defects on B cell receptor signalling. The receptor affinity of aged B cells is reduced, as they have defective somatic hypermutation [41]. The functional ability of B cells to mount specific antibody responses to primary and secondary antigens decreases in the elderly [27]. Such defects in T-cell helper function occurring during ageing [20], could have some influences on the diminished ability to produce strong high affinity and antibody response in the germinal centre [42]. The alteration in antibody production is the result of decline in T-cells function and in intrinsic B-cell function. T-cell/B-cell interactions appears to be disrupted both in aged humans and mice [39,42] (Fig. 1).

3. The immune response against tumors Recent data suggest that both the innate and the adaptive arms of the immune system are involved in the prevention of tumors. The immune system counteract the tumor cells growth through different ways: (i) protection of the host from virus-induced tumors by eliminating or suppressing viral infections; (ii) suitable eradication of pathogens and rapid resolution of inflammation thereby preventing the establishment of an inflammatory environment favourable to tumorigenesis; (iii) specific identification and elimination of tumor cells on the basis of their expression of tumor-specific antigens or molecules induced by cellular stress. By means of the latter process, referred to as tumor “immunesurveillance”, the immune system identifies cancerous or precancerous cells

and eliminates them before they can cause injury. Despite tumor immunesurveillance, tumors develop even in the presence of a functioning immune system. The recent theory of tumor immunoediting [43] is an additional explanation for the role of the immune system in tumor development. The tumor immunoediting process includes three phases which can function either independently or in sequence: elimination, equilibrium, and escape [43]. The elimination phase of cancer immunoediting is closely related to the concept of tumor immune surveillance, as the immune system detects and eliminates tumor cells developed as a consequence of failed intrinsic tumor suppressor mechanisms. The elimination phase can be complete, when all tumor cells are removed, or incomplete in the case of partial tumor elimination. In the latter event the immunoediting process consist in a temporary state of equilibrium between the immune system and the developing tumor. During this period it is possible that tumor cells either remain dormant or continue to evolve, accumulating additional changes (DNA mutations or alterations in gene expression) which can modulate the tumor-specific antigens and stress-induced antigens expressed by them. If this process continues, the immune system exerts a selective pressure by eliminating susceptible tumor clones. The equilibrium process is a component of cancer immunoediting because tumor cells in equilibrium are immunogenic, whereas those spontaneously exiting equilibrium become growing tumor and have attenuated immunogenicity. The immune selecting pressure mediated by T lymphocytes and IFN-␥ removes tumor cells more immunogenic, but leaves cells able to resist to immune system, leading tumor size to grow up. During this stage, which may hold over many years, mutations occur in the original tumor clone, producing many variants of resistant tumor cells. It has been demonstrated that elimination and equilibrium phases can be mechanistically distinguished. The elimination requires the actions of both innate and adaptive immunity, while the equilibrium is maintained exclusively by adaptive immunity. Equilibrium and escape are two distinct processes because, whereas equilibrium represents a time of tumor cell persistence without expansion, escape is characterized by progressive tumor growth. This does not forecast that every tumor cell is obliged to pass through an elimination process before it enters equilibrium, neither that every progressively growing tumor must transit through equilibrium process. However, it can be supposed that the majority of clinically apparent tumors may progress through the sequential processes of ‘elimination-equilibrium-escape’. The notion of the existence of an equilibrium state provides additional support to the idea that immunity can influence cancer development both quantitatively and qualitatively. Several findings in mouse model indicate that maintaining cancer in an equilibrium state may represent a relevant goal of cancer immunotherapy in which augmentation of adaptive tumor immunity could result in improved tumor control [44]. Moreover, these data provide mechanistic keystones for the recent idea that the quality and quantity of the immune reaction within certain tumor types are reliable prognostic indicators

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of cancer patient survival [44]. It is possible that some tumor promoting actions of chronic inflammation, such as the presence of leukocyte infiltration; the expression of cytokines such as tumor necrosis factor-alpha (TNF-␣) or interleukin (IL)-1; chemokines such as CCL2 and CXCL8; active tissue remodelling and neo-angiogenesis elevated NF-␬B activity [45,46], may be the result of the action of adaptive immunity to hold occult cancers in equilibrium [44]. The pressure exerted by the immune system during this phase is sufficient to control tumor progression, but, if the immune response remains ineffective on the removal of the transformed cells, the selection of resistant tumor cells suppress the anti-tumor immune response leading to the escape phase. This phase results from the alterations in transduction molecules, such as missing chain TCR-␨ of tumor infiltrating lymphocytes (TILs), which intervenes in their proliferation. TILs develop as manifestations of the defense against malignant cells by the host immune system. Although such cells can be found within the tumor tissues, sometimes, they fail to control the growth of tumor. Many are the mechanisms described for dysfunction of TILs with regard to the roles of immunesurveillance against cancer. Functional defects of TILs have been linked to abnormalities of signaling molecules, such as reduced ␧chain, p56lck , Zap-70, and p59fyn expression and/or their functions [47,48], Some of these signaling defects, such as those regarding ␨ chains, are reversible after in vitro treatment with IL-2 [49]. Both macrophage-derived reactive oxygen species and chronic antigenic stimulation without costimulatory effect have been linked to the loss CD3-␨ and other signaling molecules. It was further asserted that the loss of CD3-␨/␧ chains was actually one accompanying feature of tumor-induced apoptosis that shared the same FasL-mediated signaling pathway [50]. Another form of signaling defect that could potentially damage TIL proliferation/activation involves altered IL-2/IL-2R pathways [51]. In human cervical cancer was demonstrated that the failure of response to IL-2 by TILs is dependent to the downregulation of CD25 (IL-2R␣) [52]. A role of matrix metalloproteinases (MMPs) in cancer-mediated immunosuppression by IL-2R␣ cleavage has also been proposed. These cancer-derived MMPs also correlated with tumor metastasis, lymphovascular invasion in addition to immunosuppression [53]. Moreover the intracellular signaling molecule, Jak3 appears to be the cause of unresponsiveness to IL-2 by TILs in renal cell carcinoma [54]. It is well known that hypoxia can result in a tumor with more aggressive growth characteristics and more malignant phenotype [55]. Hypoxia induces apoptosis of TILs providing another growth benefit to the tumor, favouring growth of more resistant tumor cells. It has been reported that Endothelialmonocyte-activating polypeptide-II (EMAP-II) may play a role in this mechanism in colorectal cancer [56]. Furthermore, TCR-␨ is responsible for the activation of apoptotic cascades in T lymphocytes, no longer protected by Bcl-2 [57]. Soluble factors derived from tumor may block NF-␬B in haematopoietic cells directly down-regulating the anti-tumor response of immune cells, as well as induce release of IL-10 and TGF-

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␤, anti-inflammatory cytokines and inhibitor factors of both DCs and T cells activity. The cancer establishes an immunosuppressive network that allows tumor cells to resist to the elimination by the side of effector cells. Therefore tumor immune evasion is the result both of immune ignorance, for the decreased number of tumor antigens (TAs) and immune tolerance, for the reduced activation of effector T cells. During the escape phase the immune system is inadequate to counterattack tumor growth, and therefore the disease evolutes. On the basis of these views it is conceivable that the immunosenescence is an added factor which further promotes the tumor escape mechanism.

4. The acting company of the immunosenescence The immune system may schematically be divided into an ancestral/innate part, represented by monocytes, natural killer (NK) and dendritic cells (DC), and into a phylogenetically newest part, represented by adaptive immunity (B and T lymphocytes). The aging process compromises both sections of the immune system, although, in different ways (Fig. 1). The innate immunity appears to be better preserved [58], while the adaptive immunity [59], being more sophisticated and proficient to recognize fine antigenic specificities, manifests severe age-dependent modifications, which are often unfavourable to the elderly health. Nascent transformed cells can initially be eliminated by an innate immune response such as by NK. During tumor progression, even though an adaptive immune response can be provoked by antigen-specific T cells, immune selection produces tumor cell variants that lose major histocompatibility complex class I and II antigens and decreases amounts of tumor antigens in the equilibrium phase. Furthermore, tumor-derived soluble factors facilitate the escape from immune attack, allowing progression and metastasis. 4.1. T cells in the elderly Human ageing is accompanied by slight lymphopenia and a decline in immune functions. T lymphocytes from elderly individuals show a higher levels of TNF-␣-induced apoptosis, as observed in T cells from aged humans [60] and also in senescent T cells from long-term cultures [61]. T cells are important mediators of tumor immunity. A strong reduction of T-cell function and cellular immunity, as seen in the elderly, leads to a rise of carcinomas [62]. T lymphocytes play a crucial role in the neoplastic process; they may both inhibit or stimulate the formation and tumor growth. Recently, Norian et al. have found that naïve phenotype both in young and aged T cells is able to reject previously administered tumors [63]. Naïve T cells which have never encountered their specific antigen, are essential for the induction of primary immune responses against new tumor antigens, and for the generation of T-helper cell type 1 (Th1)-cell immunity which promotes

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cytotoxic T lymphocyte (CTL)-mediated responses. CTLs are competent to specifically destroy tumor cells. Further, T lymphocytes reveal decreased capability to maintain a diverse repertoire of the T-cell antigen receptor (TCR) and decreased cytolytic activity. The CD4/CD8 ratio is relatively affected in old people. Counts of T-cells subpopulations reveal an increase in the frequency of CD4+ and CD8+ T cells. The CD8+ T cells of elderly people display a resistance to apoptosis, altered cytokine profiles, various functional changes, reduced ability to respond to stress and a permanent loss of CD28 expression [64] (Fig. 1). CD 28 is one of the T cells molecules serving as receptor for co-stimulatory signals of not antigen-related signals, which are fundamental for an optimal immune response by T cells [14]. The wide pool of CD8+ CD28− T cells might allow the appearance of latent infections as well as a reduced control against acute viral infection frequently encountered [65]. CD8+ CD28− T cells also accumulate in patients with certain types of cancer. Therefore, these alterations affecting the immune response to new antigenic challenge, lead the elderly toward a susceptible state to contract diseases. Many studies examining age-related changes in T-cell subsets to disclose the cellular basis of age-associated changes in immune functions suggest that ageing leads to an increase in the proportion of memory T cells, and an equivalent decrease in T cells with the naïve phenotype. Likely, this shift is the consequence of compensatory homeostatic proliferation, due to the remarkable reduction of the naïve T cells from thymus as well as to the cumulative exposure to several pathogens and environmental antigens [20]. This decrement depends on the reduced levels [66] of IL-7 and of IL-2. The latter cytokine is critically important in the elimination of expanded T cells in the contraction stage of the immune responses [67] which leads to a further accumulation of memory cells. The contraction of T cell repertoire is responsible of the less responsiveness to new antigens. Accumulating evidences suggest that clonal expansion of memory T cells populations is the result of the impaired apoptosis. Interestingly, CD8+ T cells undergoing extensive rounds of antigen-driven proliferation in cell culture invariably reach the end stage of replicative senescence, characterized by irreversible cell-cycle arrest and a critically short telomere length [68]. Moreover, in elderly persons, the presence of high proportions of CD8+ T cells with characteristics of replicative senescence is correlated with reduced antibody responses to vaccines. The numerical change in lymphocyte is accompanied by alterations of both T-cellmediated and T-cell-dependent functions. CD4 T cells, also known as T helper cells, are believed to be the most important T cells promoting tumor rejection [69]. They are important for the production of the majority of the cytokines essential to stimulate the immune response. Diminished and/or altered cytokine patterns have been described in old age with consequent de-regulation of Th1 and Th2 responses, with a shift to the Th2 phenotype [70]. In these conditions, the leukocytes of the elderly have been found to produce fewer Th1 cytokines, such as interleukin 2 (IL-2) and IFN-␥ and, con-

versely, higher amounts of Th2 cytokines, such as IL-1, IL-6, IL-8 and IL-10, than those of young donors [71]. 4.1.1. T regulatory cells (Treg cells) The role of regulatory T (Treg) cells is extremely important to maintain the tolerance to self antigens, to protect against the aggression of infectious pathogens and to regulate the immune response against both tumor and transplantation antigens [72]. It has been reported that Treg cells are generated and instructed in the thymus to regulate the immune response against self-antigens [73]. The high quantitative presence of Treg cells in older people has been considered to be responsible of poor responses to cancer, vaccines and infectious diseases, whereas a reduced number of Treg cells might result in autoimmune disease or rejection of organ transplantation [74,75]. The Treg cells have been classified in two types, the first one derived from thymus referred as natural (nTreg) and the second type, generated from peripheral precursors CD4+ CD25− , called inducible (iTreg) [75]. The two types exert some diversities consisting on the requirement for their activation and on their mode of action and efficiency [76]. In particular, iTreg cells require MHC II-bound ligands for their activation and for their action they need of two cytokines, Interleukin-10 (IL-10) and transforming growth factor-beta (TGF-␤), belonging to the Th2 pattern. Both cytokines possess immunosuppressive functions on a variety of immune cells expressing the IL-10 and TGF-␤ receptors such as T cells, antigen presenting cells (APCs) [76]. Interestingly, Th2 cytokines pattern is increased in elderly people, suggesting a link between ageing and poor health conditions (Fig. 1). Both cytokines inhibit the induction and the function of effector cells such as cytotoxic lymphocytes (CTL) and natural killer (NK) cells [77]. Recently, it has been demonstrated that nonhealthy elderly subjects show higher number of Treg cells than young volunteers [77]. Besides, it has been hypothesized that Treg cells in elderly result resistant to undergo to apoptosis. So, the increased number of these immune regulatory cells involves negatively the defence mechanism played by CTL and NK cells, which result inhibited [77]. 4.1.2. T lymphocytes bearing the γδ TCR The percentage of blood ␥␦ T lymphocytes from elderly individuals is decreased when compared with young subjects and these cells have an activated phenotype (Fig. 1). This subset of T lymphocytes represents a link between the inflammatory response and adaptive immunity. Basal levels of TNF-␣ production by ␥␦ T cells are increased in elderly individuals whereas TNF-␣ production after stimulation is decreased when compared with young individuals. These data suggest that the high level of basal activation of ␥␦ T cells is a consequence of an ‘inflamed’ environment and not due to a higher susceptibility of ‘old’ cells to stimulation [78]. It has been indicated that in healthy donors T lymphocytes bearing the ␥␦ TCR play a role in anti-infectious and anti-tumoral immune surveillance [79]. T lymphocytes bearing the ␥␦ TCR represent a minor population of human

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peripheral lymphocytes (1–10%), most of them express the CD3+CD4−CD8− phenotype [79]. A characteristic of ␥␦ T cells is their ability to respond to non-processed and non-peptidic phosphoantigens in a MHC-unrestricted [80]. T cell stimulated with non-peptidic phosphoantigens such as isopentenylpyrophosphate (IPP), produced high levels of cytokines, particularly IFN-␥ and TNF-␣. In human, based on the composition of the TCR have been identified two main populations subsets of ␥␦ T cells. The subset expressing the V ␦ 2 chain associated with V ␥9, and the subset expressing a V ␦ 1 chain linked to a chain different from V ␥9. At birth the V ␦ 1 population predominates, while in adults V ␦ 2 is the predominant subset, perhaps as a result of selective response to environmental stimuli commonly encountered such as bacteria [81]. The analysis of ␥␦ T-cell number and function in elderly people and in centenarians has demonstrated age-dependent alterations of ␥␦ T-cells, including a lower frequency of circulating ␥␦ T-cell, an altered pattern of cytokine production, and an impaired in vitro expansion of these cells [82]. A higher percentage of ␥␦ T cells producing TNF-␣ was found in old donors and centenarians whereas no age-related difference was observed in IFN-␥ production. The decrease in the ␥␦ T-cell number was a result of an inverted V␦2/V␦1 ratio in old subjects and centenarians. After in vitro expansion, a two- fold lower expansion index of ␥␦ T-cell, and particularly of the V␦2 but not of the V␦1 subset, was found in old people and centenarians in comparison with young subjects, demonstrating the existence of a proliferative defect in ␥␦ T-cells from aged subjects. In contrast, the cytotoxicity of sorted ␥␦ T-cells was preserved in old people and centenarians [82]. Interestingly, these cells were more activated in the elderly than in young subjects, as determined by the increased expression of the early activation marker CD69 on ␥␦ T-cells from old subjects, suggesting that the high level of basal activation of ␥␦ T-cell could be due to an “inflamed” environment of the elderly host [9,78]. Since ␥␦ T cells produce cytokine, it has been suggested that are involved in coordinating the link between innate and adaptive immunity and in particular in contributing to the definition of ␣␤ T-cell responses toward the Th1 or Th2 phenotype. 4.2. Natural killer cells in the elderly NK cells are the major responsible of cytotoxic activity against spontaneously derived tumor cells, both chemically or virally. Data from the literature have shown that both the total and the relative number of circulating NK cells are significantly increased in healthy elderly people in comparison with young adult ages. The increased percentage of NK cells in the elderly is principally related to the higher number of the CD56dim population, which represents the mature NKcell subset, with a decreased CD56bright to CD56dim ratio [83]. The age-related increase of NK-cell number can be regarded as a compensatory mechanism for the decreased cytolytic activity per cell found in elderly subjects [84]. Total NK-cell cytotoxicity is steady, but, the NK-cell cytotoxicity

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on a ‘per-cell’ basis is impaired, as is the response of NK cells to IL-2 [84]. Various factors may influence the diminished functionality of NK, such as decreased responses to cytokines, reduced hormonal levels or low ion zinc availability [85] and a possible age-related changes in the protein kinase C-dependent pathway [86]. There are conflicting findings on the responsiveness of NK cells from elderly humans to the boosting action of IFN or IL-2 (Fig. 1). Decreased [87] or unchanged [88] stimulation of NK activity by IL-2 and a reduced or unchanged IFN-boosting effect have been found in peripheral blood lymphocytes from old subjects [89]. The parallel analysis of the boosting effect of IL-2 or IFN-␣ in a “healthy” elderly population yielded no change in the increase of young and elderly NK cytotoxicity against the NK-sensitive K562 cell line [85,90]. The levels of cytotoxicity are lower in old than in young animals although the relative increase of IL-12 plus IL-2 versus IL-2 alone is greater in old mice [91]. These data has been confirmed by other studies in humans which showed that IL-12 enhance NK cytotoxicity to the same degree in both young and elderly subjects, whereas the induction of IL-2activated cytotoxic cells decreased in elderly compared to young individuals [85]. In another study in humans selected according to the Senieur protocol was observed a gradual decline in both IFN-inducible and IL-2-inducible NK activities with increasing age [92]. The defect was more marked for IFN than for IL-2 responsiveness of NK cells, suggesting that the NK-cell response to IFN is more affected by age than to IL-2. Additionally was showed that the response of NK to IL-2 was impaired in proliferative status, as well as a parallel impaired expression of the CD69-activation antigen, and Ca2+ mobilization [84]. Consistent with these findings NK cells from elderly people showed a decreased proliferative response to IL-2. The role of NK cells as precursors of the so-called lymphokine-activated killer (LAK) cells has also been widely studied after long-term activation with IL-2. In humans LAKcell activity is associated primarily with CD56+ and CD16+ cells, the precursor of which is similar to NK cells. LAKcell activity is mediated by reactive cytotoxic cells which are not major histocompatibility complex restricted and are competent on lysing fresh and cultured tumors, including both NK sensitive and NK-resistant targets. Studies performed in healthy subjects revealed that LAK-cell activity induced by short-term activation with IL-2 [93] or with IL-2, IL-12, or IFN-␣, for longer incubation times [94], declined with age. The kinetic evaluation of the development of LAK cells in young and old healthy subjects, screened according to the Senieur protocol, revealed no age-related difference in terms of proliferative capacity, cytotoxicity against Daudi tumor cells, and expression of p55 or p75 IL-2 receptors [95]. The proportion of CD56+ and CD16+ cells levels increases significantly in old than in young donors suggesting that an increased number of cytotoxic cells are required in old subjects to obtain the same levels of LAK-cell activity present in young age, and that a lower cytolytic activity per cell is

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present in old age [95]. Peripheral blood mononuclear cells in continuous or short pulse culture in presence of IL-2 induced significant levels of LAK cell cytotoxicity even in elderly cancer patients [92]. Additionally, NK cells represent one of the first lines of defense during the early stages of immune activation because they synthesize many cytokines and chemokines which modulate positively or negatively the activity of both themselves and of cells of the adaptive immune response. A lower production of IFN-␥, IL-8 and chemokines was observed in either resting or activated NK cells taken from healthy elderly subjects in comparison with those from young subjects [96] (Fig. 1). The defect of NK activity in aged mice does not represent an irreversible process, since it may be recovered by hormonal and nutritional treatment [97]. Among hormonal factors relevant for NK function, it has been observed that thymic peptides or thyroid hormones but not the pineal hormone melatonin, were able to restore the impaired NK cytotoxicity of spleen cells from old mice [97]. The action of TSH and thyroid hormones is specifically directed toward lymphokineenhanced NK activity. Among the nutritional factors, either zinc or a lipid mixture, which increases membrane fluidity, called “active lipids”, are able to prevent age-associated impairment of basal NK cytotoxicity in aged animals [98]. The NK activity involves either the granule exocytosis pathway or the Fas pathway, both of these pathways act to induce apoptosis by a different mechanisms the first utilizes perforin and granzymes, while the Fas-mediated mechanism plays a part in lymphocyte-mediated killing and shows a minor role in immunesurveillance. Mice lacking T cell and NK cell cytotoxic effector pathways have also been shown to develop spontaneous tumors. The importance of perforin, a cytotoxic molecule used by cytotoxic cells such as CD8+ T cells and NK cells to form membrane pores in target cells in immune defence, rises from the evidence that mice lacking of perforin develop lymphomas with age. In a prospective study, following middle-aged and elderly Japanese over 11 years, the incidence of cancer was increased in those with lower initial NK cytotoxic activity [99]. In gastric cancer patients, lower NK cytolytic activity at diagnosis correlates with higher tumor volume, metastases and worse prognosis [100]. An increase in the expression of NK-associated receptors (NK-Rs) on CD3+ T lymphocytes has been observed in elderly individuals. Similar results have been found in other clinical conditions that involve chronic activation of the immune system such as infections, autoimmune diseases and tumors. The expression of NK-associated receptors is seen preferentially in CD8+ CD28− T cells, a subset that is increased in elderly individuals. CD8+ CD28− NK-Rs+ T lymphocytes may represent cytotoxic effector cells that have undergone a process of replicative senescence after chronic activation. The expression of NK-associated receptors in these “effector/senescent” cells probably contributes to the regulation of their cytotoxic function [86]. NKT cells represent a subset of T cells characterized by the expression

of the canonical V␣24J␣Q TCR, recognition of CD1d, and secretion of large amounts of IL-4 and IFN-␥. V␣24+ cells represent only a minor subset of T lymphocytes but this is decreased in elderly individuals and has a different pattern of NK-associated receptor expression. 4.3. Antigen-presenting cells in the elderly Antigen-presenting cells (APCs), includes dendritic cells (DCs) and macrophages. Mainly DCs are regarded as the most effective APCs that are indispensable in activating specific T cells and in initiating an adaptive immune response. Immature APCs are found in peripheral tissues where they capture antigens for processing and deliver them to lymphoid organs. Mature APCs are specialized in presenting processed antigens to T lymphocytes [101]. The migration of APCs from the site of antigen deposition to lymphoid organs is a critical initial step during the induction of an immune response. Several evidences reported that ageing does not affect the number of APCs or their function, while others have demonstrated the occurrence of age-related alterations of their antigen-presenting capacity [102]. Ageing may affect the antigen-presenting capacity of APCs by influencing their migratory capacity, their antigenprocessing capacity, the levels of cytokines in their microenvironment, the presence of co-stimulatory signals on their surface (Fig. 1). The crucial event in the activation of a cellular immune response against tumor cells is the presentation of antigenic peptides by APCs to CTLs through MHC class I molecules. The generation of MHC class I-binding peptides depends on the intracellular immunoproteasomemediated proteolysis mechanism. Actually, one of the first alterations in ageing APCs may affect the crucial step of antigen presentation—i.e., the degradation of endogenous proteins, and then the generation of peptides for presentation by MHC class I molecules. Many experimental evidences have demonstrated an age-related injure of proteasome structure and function which depend on the reduced proteasome expression replacement of proteasome subunits, and development of inhibitory cross-linked proteins [103]. It has been suggested that there is a decrease in immunoproteasome content [104]. Immunohistochemical and PCR analysis revealed a deficiency of the immunoproteasomes low molecular weight protein 2 and low molecular weight protein 7 in the primary tumor cells, which affects the quantity and quality of generated T-cell epitopes and might explain the resistance to killing. This is supported by other studies, demonstrating that the resistance to killing can be partially reversed by pre-exposure of the tumor cells to IFN-␥, which is known to induce the immunoproteasomes [105]. Another defect occurring in APCs during ageing is the expression of costimulatory molecules and the regulation of their activity. It is known that in order to activate naïve T lymphocytes is not sufficient a signal received through the antigen T-cell receptor (TCR), but a second co-stimulatory signal is required to induce effective immune responses. This co-stimulatory

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activity, present in APCs, appears to be required to signal the presence of a non-self-antigen to antigen-specific receptors on T lymphocytes. Nevertheless, the total number and the expression of MHC I and II, CD80, and CD86 both on immature and mature APCs do not appear to differ significantly in young and old mice [106], DCs in germinal centres of aged mice are deficient in expression of important co-stimulatory ligands such as CD86 [107], which promote the induction of anergy in the antigen-specific T cells. Among the factors regulating the expression of co-stimulatory activity on APCs there is a group of receptors of the non-clonal innate recognition system termed pattern-recognition receptors (PRRs), such as toll-like receptors (TLRs) which recognize conserved molecular patterns. TLRs are shared by vast group of microbial elements and are competent to distinguish between selfand non-self-pathogen-associated structures and to indicate the presence of a pathogen to the APCs [108]. A decreased TLR expression and function it has been observed on APCs from aged mice, which expressed significantly lower levels of TLRs (TLR 1–9), and produced lower levels of cytokines when stimulated with ligands for TLRs when compared with young mice [109]. Macrophages and DCs specifically bind to apoptotic cell-associated molecular patterns through TLRs and intervene in the phagocytosis of apoptotic bodies [110]. Furthermore, TLRs expressed on APCs are receptors for heat shock proteins (HSPs) and mediate HSP signalling [111]. Expressions of HSPs is induced by different types of stress induce. They function as chaperones improving antigen processing and presentation through binding to short peptides. The chaperoning of antigenic peptides into APCs by connection with tumor cell-derived HSPs is an efficient way of immunizing against a variety of tumors. Therefore a decreased TLR expression and function during ageing could lapse the antigen-presenting function resulting in an impaired immune activation of both innate and adaptive responses. APCs differentiation and function are influenced by cytokines production. It has been observed that IL-10, a cytokine which suppresses cell-mediated immunity and DC maturation and function is elevated in healthy old people [71]. The inhibitory effects of IL-10 on the accessory functions of APCs, includes the conversion of immature DCs into tolerating APCs, the suppression of IL-12 production by activated DCs, the downregulation of CD40 expression on DCs from elderly subjects [112]. Moreover the production of cytokines important for the differentiation and functional activity of APCs, like IL-4 and IL-12, declines in exhausted elderly people [113]. As a result age-related changes in cytokine levels may not only directly influence immune responses but may also alter the balance and maturation of APC subsets. Moreover, the chemotactic capacity of DCs is affected by the ageing process [114]. Old mice show a lower expression of the mRNA for the migratory CCR7 chemokine receptor and a lower lymphocyte cytotoxicity. Moreover, APCs from aged mice induce a reduced number of CD8+ T cells producing IFN-␥ in comparison to APCs from young animals [102]. The information that CCR7 is increased in mature APCs up to the levels found in young

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Table 2 Dendritic cells in elderly.

Cytokine production Appearance Markers Function

Changes with aging CD expression

mDC

pDC

Producing IL-12 Monocyte-like Presence of myeloid markers Driving TH 1 responses

Producing IFN-␣ Plasma cells-like Absence of myeloid markers Involved on the pathogenesis of autoimmune diseases No decreased CD123+

Decreased CD11+

pDC: plasmacytoid dendritic cell; mDC: myeloid dendritic cell.

animals and that in vivo migration of APCs to regional lymph nodes was higher in old than in young mice, implies that an increased chemotactic capacity of old APCs may be required to balance their reduced antigen presentation to cytotoxic lymphocytes [102]. This hypothesis is further emphasized by the evidence that the lower CTL cytotoxicity induced by APCs from old mice has been attributed to an age-related defect of antigen presentation rather than to an intrinsically lower frequency of CTLs. 4.4. Dendritic cells in the elderly Dendritic cells (DCs) have a crucial role in both activation of antigen-specific immunity and maintenance of tolerance, providing a link between innate and adaptive immunity. Dendritic cells are involved in antigen presentation in vivo. Sallusto and Lanzavecchia [115] have shown that monocytes, derived from the peripheral circulation, can be readily activated into dendritic cells by culturing with GM-CSF (granulocyte-macrophage colony stimulating factor) and IL-4. A recent work reports that the frequency of PBDCs (peripheral blood dendritic cells) progressively declines with age, particularly the myeloid sub-population of DCs (Table 2), with a following decreasing of immune response against infections and tumors [116]. It also indicated that the frequency of CD34+ cells progressively declines with age, contributing to the reduced availability of DCs. It may be due to increased levels of vascular endothelial growth factor (VEGF), which impairs the differentiation of CD34+ into mature DCs [117] (Fig. 1), thus influencing the decline of protective immunity and the arising of autoimmune disease, and malignancies. The same work demonstrated that the ability of PBDCs to produce IL-12 upon lipopolisaccaride (LPS) stimulation progressively declined with age, while their ability to produce IL-10 remained unaffected [116]. The decreased production of IL-12 may contribute to the imbalance between T-helper 1 and T-helper 2 subsets, leading to a prevalence of Th2 cytokines observed in the elderly [118]. 4.5. Macrophages in the elderly Macrophages are important cellular elements of innate immunity. They kill bacteria, viruses, parasites and tumor

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cells either directly or through the release of mediators, such as IL-1, IL-6, TNF-␣, IFN-␥, which, in turn, activate other immune cells. Recent studies suggest that macrophage number and function are modified with ageing. A significant expansion of CD14dim /CD16bright circulating monocytes, which are considered the phenotypic activated cells, has been reported to occur in elderly people [119]. The constitutive or induced production of IL-1, IL-1 receptor antagonist, and IL-6, was found to increase in monocytes from elderly subjects [119,120]. Nevertheless, in a recent study conducted in young and old subjects screened according to the Senieur protocol, no age-related difference was noted in the total amounts of IL-1␤ and in IL-6 serum levels after normalizing for circulating monocytes [121]. Monocytes from old donors, when compared with monocytes from young subjects, displayed decreased cytotoxicity against tumor cells following LPS activation. This alteration is associated with a decrease in IL-1 secretion and production of reactive oxygen intermediates such as NO2 and H2 O2 [122] (Fig. 1). Macrophages from aged mice, in vitro activated with IFN␥ and LPS, exhibited reduced antitumor activity and impaired capacity to produce TNF-␣, IL-1 and nitric oxide, critical monokines and effector molecules competent to directly inhibit tumor growth [123]. A lower expression of the production of MHC class II gene was found on the cell surface of macrophages from old mice after incubation with IFN-␥ [124]. Recent findings have been reported on the expression of TLRs on macrophages in ageing mice [125]. Both splenic and activated peritoneal macrophages from old mice have been found to express significantly lower TLR levels. These cells also secreted lower levels of IL-6 and TNF-␣ when stimulated with known ligands for TLR compared to those in young mice. Bone marrow-derived macrophages obtained from aged mice have a normal proliferative response to MCSF but not to GM-CSF or IL3. The expression of cyclin D1 is up-regulated by GM-CSF treatment only in macrophages from young mice. GM-CSF treatment induces the expression of Bcl-XL but there is no induction of the antiapoptotic gene A1 in aged macrophages and GM-CSF-dependent differentiation to DCs was reduced. The expression of the MHC class II complex IA␣ gene after incubation with IFN-␥ is lower in aged macrophages due to impaired transcription [124]. 4.6. Polymorphonuclear leukocytes in the elderly Polymorphonuclear leukocytes (PMNs) are important effectors in the induction of immune responses and participate actively in the antitumor immune surveillance. In the tumoral infiltrate after in vivo immunization both in young and in old age [126]. PMNs represent one of the main cellular populations. The peritumoral and intratumoral release of cytokines withdraw PMNs as demonstrated by the evidence that in mice challenged with IL-2-engineered tumor cells activated PMNs and macrophages directly kill and reject tumor both in young and old age [127]. Several studies show that the neutrophils number in blood and neutrophil precursors in

bone marrow, as well as the response to GM-CSF and IL-3, are not lowered in the healthy elderly, even though, the proliferative response of neutrophils precursor cells to G-CSF was found reduced [128]. In vitro studies of leukocyte chemotaxis have revealed that migratory responses of neutrophils from healthy old subjects are either unaffected [129] or only to some extent reduced [130]. Several studies report a remarkable decrease in the PMNs phagocytic activity from aged individuals [130].

5. Genetic alterations in the elderly Intense investigations have been focused on the nature and polymorphisms of genes that regulate immune responses and their relationship with longevity. Nuclear translocation of transcription factor NF-␬B is regulated by targeted degradation of phosphorylated I␬B␣ by the 26S proteosome via the ubiquitin-proteosome pathway. Chymotrypsin-like activity of the proteosome is largely responsible for the degradation of the NF-␬B inhibitor, I␬B␣, and is decreased in elderly individuals. A defective proteosomal degradation of I␬B␣ results in lowered induction of NF-␬B which may contribute to immune dysfunction during ageing [131]. It has also been suggested that the proteosomal protein LMP2 codon 60 polymorphism modulates TNF-␣ responses. Comparisons between two alleles R (Arg) and H (His) in elderly and young individuals show that while there were no statistically significant differences in young individuals, H carriers in the elderly group were less susceptible to TNF-␣-induced apoptosis. The differences between TNF-␣-induced apoptosis of PBMC from young and elderly people could be relevant to the progressive increase of inflammatory status which characterizes human ageing [132]. The DNA-dependent protein kinase complex is involved in DNA damage recognition and repair and includes the Ku70/Ku80 heterodimer, or Ku, binding DNA termini of breaks without sequence specificity, and the catalytic subunit DNA-PKcs. Ku, is the central component of the non-homologous end joining (NHEJ) pathway of double strand break (DSB) repair. Because Ku forms a ring through which the DSB threads, it likely becomes topologically attached to DNA during repair. DNA-binding of nuclear Ku is enhanced in lymphocytes by an IL6-type cytokine in young subjects but not in elderly individuals. Ku is associated with the kinases involved in signal transduction events after gp130 triggering, such as Jak2 and Tyk2, in the cytoplasm of PBMC from young, but not from elderly subjects [133]. Differences in the frequencies of several cytokine alleles may also play a role in the remodelling of the immune response with ageing. There are some data indicating that elderly individuals show cytokine production patterns which differ from those of the young, characterized by decreased production of type 1 cytokines and increased production of type 2 cytokines. Relatively unexplored thus far are also differences in chemokine secretion and receptor expression, which may also be critical regulators of immune responses

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[134]. Some polymorphisms at promoter regions of TNF-␣, IL10, and IFN-␥ have also been associated with susceptibility to infections. In this regard, centenarians have a different frequency of the alleles defined by a polymorphism at the 5 flanking region of the IL-10 gene coding sequence that results in a high IL-10 producer phenotype. IL-10 exerts powerful inhibitory effects on the action of pro-inflammatory cytokines as TNF-␣. Recent data suggest that the −174C/G polymorphism exerts a cell-specific control on IL6 production and is associated with gender [135]. Several cytokine-deficient mice also develop spontaneous malignancies [136]. In one study, approximately 50% of IFN␥-deficient C57BL/6 mice develop T cell lymphomas [137]. Furthermore, the spectrum of tumors observed in IFN-␥and STAT1-deficient mice do not overlap, despite STAT1 being a crucial signaling molecule downstream of the IFN␥ receptor, indicating either that these molecules have some non-overlapping activities or that the background strain has a modifying influence on tumor type. In addition, C57BL/6 mice lacking both IFN-␥ and perforin display accelerated B cell lymphoma onset compared with perforin-deficient mice [137], indicating that IFN-␥ has an important role in modifying the progression to B cell lymphoma in perforin-deficient mice. B cell lymphomas also arise in mice lacking both perforin and beta-2 microglobulin ␤2m, and tumor onset is earlier and occurs with increased prevalence compared with mice lacking only perforin. In addition, B cell lymphomas derived from mice lacking both perforin and ␤2m are rejected by either NK cells or ␥␦T cells following transplantation to WT mice, rather than by CD8+ T cells (as in tumors derived from mice lacking only perforin), demonstrating that cell surface expression of MHC class I molecules by tumor cells can be an important factor in determining which effector cells mediate immune protective effects [138]. Intriguingly, mutations in the gene encoding perforin have also been identified in a subset of lymphoma patients [139], although it is not clear whether this contributes to disease. Furthermore, mice deficient for both IFN-␥ and GM-CSF have also been found to develop tumors with age; in this case, tumor development is associated with acute or chronic inflammatory lesions in a range of organs, and maintaining mice on the antibiotic enrofloxacin prevents, or at least delays, tumor onset [140]. Mice insensitive to IFN-␥ and lacking of gene p53 developed tumors more rapidly than wild type mice. Further analysis demonstrated that IFN-␥ controlled the growth of sarcomas, as well as the initiation, growth and spread of tumors in mice [43]. Collectively, these findings demonstrate that the immune system can suppress tumor development, but they do not constitute proof for tumor immunoediting per se. These studies confirm the possible link between tumor immunity and autoimmune or infection-induced inflammation. The finding that antibiotic treatment could prevent tumor development in Gm-csf−/−Ifng−/− mice raises the possibility that rather than directly eliminating tumor cells, the immune system might prevent tumor growth by the timely elimination of infections, thereby limiting inflammation, which is known

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to facilitate tumor development [141]. However, this finding cannot be generalized, as Rag2−/− and Rag2−/−Stat1−/− mice maintained on the same antibiotics and housed under strict specific pathogen-free conditions still display heightened tumor incidence despite testing negative for common pathogens with known links to malignancy and showing no signs of idiopathic inflammation [142]. Mice lacking the death-inducing molecule TNF related apoptosis-inducing ligand (TRAIL) or expressing a defective mutant form of the death-inducing molecule FASL have also been shown to be susceptible to spontaneous lymphomas that develop with late onset [143]. IL-12 and IL-18 are important IFN-␥-inducing cytokines; however, studies of aging have demonstrated that neither IL-12- nor IL-18-deficient mice display increased incidence of tumor development compared with WT mice [137]. These spontaneous lymphomas are of B cell origin, and, when transplanted into WT mice, are rejected by CD8+ T cells [144]. Curiously, with age, 50% of mice lacking the ␤2 subunit of the IL-12 receptor (IL-12R␤2) develop plasmacytomas or lung carcinoma in the context of the autoimmune disease immune complex mesangial glomerulonephritis [136]. It is presently unclear why IL-12-deficient mice on the same genetic background as the IL-12R␤2-deficient mice do not display either autoimmunity or spontaneous tumor development. These aging studies have clearly demonstrated a critical role for cytotoxic pathways in immunoregulation and/or immunosuppression of spontaneous tumor development in mice. Mitochondrial (mtDNA) damage has been investigated as a biomarker using PCR-based methods in combination with reference strand conformational analysis (RSCA) to identify genotype associations within successfully aged populations using polymorphism in the genes of the KIR (killer immunoglobulin like receptors) involved in T and NK cellmediated cytotoxicity, cytokine, and oxidative stress defence systems [145]. Since metallothioneins (MTs) participate in zinc homeostasis and influence the secretion of proinflammatory cytokines they have been examined as potential markers of immunosenescence. Metallothionein gene expression is transcriptionally induced by a variety of stressing agents to protect cells from reactive oxygen species. The level of MT mRNA is decreased in lymphocytes of centenarians as compared to old normal populations. Zinc supply in ageing corrects the defect and prevents metallothioneins from sequestering intracellular zinc. As a result, MTs regain a protective role [146]. Studies of insertional mutagenesis and cDNA library transfer aimed to the identification of genes involved in the control of cellular differentiation and apoptosis have identified the retinoic acid receptor alpha (RAR␣) and c-myb as important regulators of myeloid cell differentiation. Interestingly, the gene Ras-induced senescence (RIS-1) located at 3p22, a chromosomal region containing several tumor suppressor gene, has been proposed to participate in anti-tumor responses that resemble cellular senescence and that are elicited by oncogenes such as Ras [147]. Studies

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with transgenic mice carrying extra-genomic copies of the tumor suppressor p53 have been used to address a number of questions related to tumor suppression and ageing in vivo [148]. The DNA array technology in senescent T lymphocytes has indicated alterations in redox-sensitive signalling genes, such as AP-1 and B-ATF [149]. Other alterations in regulators of gene expression may include altered methylation in ageing and altered histone deacetylization, which also changes with age in peripheral blood mononuclear cells [150]. Ageing results in changes in neutrophil as well as T lymphocyte signal transduction pathways. Different patterns of PKC isoenzymes can be observed between young and elderly individuals. A decrease in exogenous and endogenous tyrosine kinase activities (ZAP70, p56lck) after CD3 stimulation is associated with ageing. IL2-mediated signalling was also found to be altered with ageing (Jak3 and STAT3 and 5). The changes observed in signal transduction with ageing may be due to alterations of cell membrane fluidity as a consequence of an increment of cholesterol and are liable to modulation [151]. In PMNLs the GM-CSF signal transduction pathway is altered in elderly individuals showing a diminished tyrosine phosphorylation of Jak2, STAT3 and 5 [152]. T cells of old mice and especially the Pgp+ CD4+ subpopulation have an increased activity of ␮-calpain, a protease that participates in the regulation of cellular proliferation and signal transduction. In humans, however, calpain activity in general decreases with increasing age [153].

TGF-␤, or IL-10 or other cytokines which tend to suppress inflammatory T-cell responses and cell-mediated immunity, which are needed to control tumor growth and to destroy tumor cells. In old subjects, these suppressive cytokines released by tumor cells may synergize with immunosuppressive cytokines (TGF-␤, IL-10 and others) which are already overproduced by leukocytes up to elevated concentrations able to impair anti-tumor immune responses. Furthermore, IL-6, another cytokine overproduced in the elderly, has been reported to increase the expression of the TGF-␤ receptor, thus facilitating this mechanism of tumor immune escape [156]. Prostaglandins are other factors that have been involved in cancer-induced immune suppression. Tumor cells produce prostaglandins which can inhibit various immune functions. The above examples lend weight to the idea that immune suppression induced by tumor cell-derived prostaglandins may have particular implications in ageing, since lymphocytes from elderly subjects are now known to be sensitive to inhibition by prostaglandins in comparison with lymphocytes from younger individuals [157]. Several mechanisms of active immune escape have been proposed to explain the incapacity of the immune response in rejecting tumors. It seems that these mechanisms of immune escape play an important role in the aged host even though the exact relevance of tumor-induced immunosuppression in the early phases of tumor development in the elderly remains to be proven.

6. Tumor-induced immunosuppression in the elderly

7. Inflammaging cytokines and tumorigenesis

Immunosenescence, influence the ability of aged subject to react against exogenous antigens and, in particular, reduce the capacity of anti-tumoral immune defences in the elderly [154]. Besides these, other factors may contribute to triggering spontaneous tumor growth without being rejected by the immune system: passive mechanisms, such as the lack of either distinctive antigenic peptides or the adhesion and co-stimulatory molecules needed to elicit a primary T-cell response; and active mechanisms through which tumors can avoid or evade immune attack. Some evidence suggests that at least some of the mechanisms used by cancer cells to escape immune clearance might be more effective in ageing. One of these is related to the Fas ligand/Fas receptor (FasL/FasR or CD95L/CD95) interaction. FasL is a key molecule in normal immune development, homeostasis, modulation, and function and acts by inducing apoptosis of sensitized cells through interaction with its own FasR receptor, expressed on their surface. To date, the expression of functional FasL has been reported in several distinct lineages of tumors [155]. As mentioned before, the increased FasR expression observed on aged leukocytes might facilitate the immune escape of tumors expressing FasL in elderly patients by promoting the apoptosis of TILs. Another mechanism which enables tumors to evade immune rejection is the release by tumor cells of immunosuppressive cytokines. Many tumors produce

Ageing is accompanied by a low-grade chronic, systemic up-regulation of the inflammatory response. The inflammatory changes are common to most age-associated diseases this process is termed “Inflammaging” [9]. Inflammaging results in both decreased immunity to exogenous antigens and increased auto-reactivity. Thus, the beneficial effects of inflammation devoted to the neutralization of harmful agents early in life become detrimental late in life. Cancer also represents an immunologic challenge, which upregulates the systemic immune response. Thus, tumor-related hyperinflammation and inflammaging synergistically lead to the systemic priming of inflammatory mediators. A large number of evidence reports the relationship between inflammation and cancer, and the importance of soluble mediators in tumor development and progression. A major force able to drive a chronic pro-inflammatory state during aging may be represented by persistent viral infections by CMV, which has determined by the frequency and the absolute number of viral antigen-specific CD8+ T-cells in subjects older than 85 years, who were serologically positive for CMV. The majority of CMV+ T cells belong to the CD28− subpopulation. Therefore, the chronic antigenic stimulation induced by persistent viral infections during aging bring significant adaptations among CD8+ subsets, which are evident in the presence of CMV persistence [158]. The age-dependent

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expansions of CD8+CD28− T-cells comprising the majority of CMV-epitope-specific cells, highlights the importance of chronic antigenic stimulation in the pathogenesis of the foremost immunological alterations of aging and may favour the appearance of several degenerative pathologies (arteriosclerosis, cancer, dementia) all of which are characterized be an inflammatory process. The inflammatory insults leads to up regulation of nonspecific proinflammatory cytokines such as IL-1␣/␤, IL-6, interferon (IFN)-␣, and tumor necrosis factor (TNF)-␣ [159]. These cytokines, subsequently, induce the expression of acute-phase protein (APP) and pro-inflammatory chemokines [159]. Such unresolved chronic inflammation is associated with increased conversion of normal cells to preneoplastic foci. Cytokines appears to play a paradoxical role for in the development of cancer [160]. To one side, cytokines induce tumor cells death, directly or through enhancing immune response. To the other side, cytokines contribute to carcinogenesis, as a consequence of autocrine production, due to chronic inflammation [161]. Therefore, chronic inflammation and over production of cytokines is an additional mechanism of carcinogenesis [162]. It has been suggested that, pro-inflammatory cytokines and chemokines could be increased by carcinogens contained in food, smoking and industrial products [162]. The inflammatory scenario that characterizes inflammaging constitutes a highly complex response to various slight internal and environmental inflammatory stimuli mediated mainly by the increased circulating levels of proinflammatory cytokines [159]. Inflammaging also generates Reactive Oxygen Species (ROS) causing both oxidative damage and eliciting an amplification of the cytokines’ release, thus perpetuating a vicious cycle resulting in a chronic systemic pro-inflammatory state where tissue injury and healing mechanisms proceed simultaneously and damage slowly accumulates asymptomatically over decades and is a major determinant both of the ageing process and of the development of age-associated diseases [160]. The cytokines contribute to tumor growth, progression and immuno-suppression, by regulating cell death, survival or differentiation, as well as angiogenesis. Studies on malignant cells of papillary thyroid cancer have been shown that pro-inflammatory cytokines are activated by oncogene expression, promoting the growth and the spread of the malignant cells [160]. The most abundant cytokines present in tumor sites and in the tumor microenvironment belong to the pro-inflammatory type, as confirmed by the proportion of Th1 and Th2 cells observed in patients with bladder and colorectal cancer compared to the healthy population. In fact, the Th1 cells, producing IFN-␥ or IL-2, were significantly reduced; whereas, Th2 cells, producing IL-4, IL-6, IL-10, were markedly increased [163]. Furthermore, in human cervical carcinoma the CD3+ tumor infiltrating T lymphocytes displayed enhanced Th2 cytokine patterns and increased IL4 production, whereas IFN-␥ production was reduced [164] (Fig. 1).

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It has been reported that the pro-inflammatory interleukin 1 alpha (IL-1 ␣) plays a role in tumorigenesis, in particular in the promotion of cervical carcinoma growth [165]. The paracrine secretion of IL-1␤ may influence the growth and the chemoresistance of pancreatic cancer [166] and induce the production of angiogenic factors in lung carcinoma in vivo [167]. Studies performed in mice models have shown that the lacking of IL-1␤, may be responsible of the absence of metastasis both in melanoma cells models and in breast and prostate cancer [168]. Another cytokine playing an important role both in inflammatory diseases and in tumor promotion is the TNF-␣ [169], which may affect tumor cell survival through the induction of genes encoding NF-␬B-dependent anti-apoptotic molecules [170]. Additionally, TNF-␣ plays an important role in the initiation of tumor by stimulating the production of nitric oxide (NO) and reactive oxygen species (ROS), which can lead to DNA damage and mutations [171]. Moreover, TNF␣ favours tumor progression, promoting angiogenesis and metastasis and allows tumor escape by suppressing many T cell responses and macrophage cytotoxic activity [172]. Enhanced levels of TNF-␣, due to genetic polymorphisms increase the risk of multiple myeloma, hepatocellular carcinoma, bladder, gastric and breast cancer, and then it correlates with poor prognosis of haematological malignancies [169]. Promising results come from treatment with antibody against TNF-␣ in hepatocellular carcinoma (HCC) during promotion stage. These specific antibodies led to apoptosis of transformed hepatocytes and a failure to the tumor progression [173]. IL-6 is a potent pleiotropic inflammatory cytokine playing a pivotal role in growth and promotion of tumor and behaving as an anti-apoptotic factor. The signaling pathway used by IL-6 (e.g. NF-␬B and STAT3) controls tumor development through a direct effect on tumor cells. The paracrine secretion of IL-6 acts as a growth factor for multiple myeloma, non-Hodgkin’s lymphoma, bladder, colorectal and renal cell carcinoma [174]. The signaling pathway of soluble IL-6 receptor appears to be responsible of the development of colon cancer [175], as enhances, remarkably, the production of IL-6 from T cells [175], contributing to T cell survival. Antagonist of IL-6 might be useful for the treatment of colon cancer. The cytokines belonging to the Th2 pattern, such as IL-10, are involved in tumor growth and in angiogenesis induction. Further, both IFN-␣ and IFN-␤ have been considered as components of tumor surveillance system [176] and affect negatively tumor growth, since they participate to shape innate immune system, including dendritic cell maturation and NK-cells responses [177]. Many experimental evidences show a contradictory function of IL-10, which is in some cases pro-tumorigenic and in other cases anti-tumorigenic. The development of cancer is inhibited when IL-10 inhibits the production of proinflammatory cytokines, as IL-6, IL-12 and TNF-␣ [178], by blocking the activation of NF-␬B [179]. Likely, IL-10 inhibits

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tumor growth, down-regulating the expression of MHC-class I on cell surface, thus enhancing tumor cells lysis mediated by NK cells [180]. The IL-10 is also involved in the modulation of apoptosis and in the suppression of angiogenesis during tumor regression. IL-10 could affect negatively the release of pro-angiogenic factors from tumor stroma cells [181]. In contrast, increased plasma levels of IL-10 have been found in patients bearing diffuse large B cell lymphoma, and it correlates with poor prognosis [182]. It has been reported that IL-10 promotes the development of Burkitt lymphoma through the production of a B cell-activating factor of the TNF family/B lymphocyte stimulator (BAFF/BLyS), which in turn, promotes B cells and lymphoma survival [183]. Moreover, patients with gastric cancer showed increased IL-10 expression, that correlates with attenuated CD8+ T cell infiltration and poor prognosis [184]. Likely, IL-10 favours tumor growth suppressing adaptive immunity, leading to the tumor escape from immunesurveillance [185]. Anti-tumor effect is played by IL-12, which promoting Th1 adaptive immunity and CTL responses, inhibits tumorigenesis and induce regression of established tumors [186]. The negative effects of IL-12 on tumor development might be strengthen by IFN-␥, that shows a direct toxic effect on tumor cells and inhibits neo-vascularization [186]. IL-13 carries out a suppressive action on cellular mediate immunity [187] and so, acting directly on neoplastic cells influences the tumor growth. Recently it has been reported that also IL-17 has a protumorigenic role, likely due to pro-angiogenic activity [188]. This cytokine induces pro-inflammatory cytokines such as IL-1␤, IL-6, TNF-␣. Elevated expression of IL-17 has been found in human cervical carcinoma and non-small cell lung carcinoma (NSCLC) [188], as well as in C57BL/6 mice bearing fibrosarcoma [189]. IL-18 is linked with disease progression in large granular lymphocyte leukaemia [190]. A cytokine not generally considered as a Th2 cytokine, but with Th2-like cytokine activities, is the IL-23 which plays a contradictory role. To one hand, it enhances proliferation of memory T cells and the production of IFN-␥ and IL-12 by activated T cells. On the other hand, it induces the production of IL-17, promoting inflammatory reactions [191]. In a murine model the absence of IL-23 leads to a marked decrease of local inflammation in tumor microenvironment and a higher presence of T cytotoxic cells, thus playing a functional defence against cancer development [192]. In addition, this cytokine favours a pro-tumor microenvironment [192].

8. Chemokines and tumorigenesis The chemokines are cytokines of a chemoattractant family and play a central role in leukocyte recruitment to the sites of inflammation and in the host response against infection. To date have been identified more than 40 chemokines, which have been subdivided into four families on the basis

Table 3 Chemokines receptors and tumorigenesis. Name of chemokines receptor

Properties pro-tumorigenesis

CXCR 2 CXCR 4 CCR 2

Angiogenesis Metastatic spread of many tumors Recruitment of macrophages into tumor microenvironment Metastasis into sentinel lymph nodes

CCR 7

of the position of their cysteine residues [193]. The ␣ and ␤ chemokines containing four cysteines appear to be the largest families. In the ␣-chemokines, one amino acid separates the first two cysteines residues (cysteine-x amino acid cysteine or CXC) whereas in the ␤-chemokines, the first two cysteine residues are adjacent to each other (cysteinecysteine or CC). Two chemokines that do not fit into this classification are lymphotactin and fractalkine [194]. The chemokine are induced by early pro-inflammatory cytokines, such as IL-1 and TNF-␣. In addition, IFN-␥ and IL-4 can induce the production of chemokines and synergize with IL-1 and TNF-␣ to stimulate chemokines secretion [195]. The CXC chemokines are active on neutrophils and lymphocytes whereas CC chemokines act on several leucocytes subsets including monocytes, eosinophils, dendritic cells, lymphocytes and NK cells but not neutrophils [196]. Recent evidences report that aged T cells showed changes in chemokines receptor expression, such as increased CCR1, 2, 4, 5, 6, 8 and decreased CCR7 and 9 in CD4+ T cells [197]. On the basis of these changes, mRNA levels increased, thereby enhancing protein expression [197]. It is interesting notice that a reduced expression of CCR7 in animals, involved on cell homing to secondary lymphoid organs [198], may explain the age difference in T cell trafficking [197]. Also the chemokines are involved in tumor development, as they have a direct tumor growth factor effect, as well as they affect angiogenesis process and metastatic invasion (Table 3). In addition, they may act indirectly, recruiting macrophages in tumors and stimulating them to release other growth factors for cancer development. However, some chemokines and their receptors are involved in anti-tumor immunity. The CXCR3-ligands, such as CXCL9, CXCL 10, CXCL11 are able to attract Th1, CD8 and NK effectors to the tumor microenvironment. They could have also angiostatic effect binding with high affinity CXCR3+ microvascular endothelial cells [199]. CCL5/RANTES is the first chemokine detected for mediating anti-tumor immunity in part through direct T cell effector recruitment [200]. It has been proposed that other CCR5-ligands were involved in T cell infiltrates of nasopharyngeal carcinoma [201] and epithelial ovarian tumors [202]. The expression of high levels of RANTES in breast and cervical carcinoma is found in advanced diseases [196]. Furthermore, experiments on mice models bearing tumor have identified CXCL 10/IP10, as a required factor for IL-12 mediated CD8-dependent anti-tumor immune responses [203]. The transfection of lymphotactin CXCL1 into tumor cells

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leads to CD4 and CD8 T cell infiltration and tumor rejection [204].

9. Concluding remarks Dysregulated function of immune system affecting older people, involves both the reaction against infectious pathogens and the anti-tumor defence, leading to a decrease of the activity in both circumstances. Since many mechanisms involved in the ageing process share molecular ways implicated in carcinogenesis processes [205], it is understandable the existence of relationships between ageing and risk of tumor development. Particularly, one of these risks consists with the impairment of apoptosis process. Normal cells are able of a finite number of mitotic cycles before entering a state of replicative senescence prior to cell death. Replicative senescence in fibroblast is associated with increased Bcl2 expression and resistance to apoptosis [206,207]. The Bcl2 gene promotes malignancies by decreasing apoptotic cell death [208]. Bcl2 has been shown to protect cells against variety of cytotoxic stimuli including anticancer drugs. Spaulding et al. have shown that senescent CD8+ T cell cultures show reduced apoptosis in response to a wide variety of treatments and diminished caspase-3 activity compared with quiescent early passage cultures from the same donor [68]. Moreover, T cell replicative senescence is also associated with increased Bcl2 expression which may contribute to the prolonged survival of senescent CD8+ T cells in culture [68]. The nature of the immunological effectors, which induce apoptosis, is still debated. According to one hypothesis, interaction between antigen presenting cells and T cells leads to the remarkable increment of pro-inflammatory cytokines IL-1, TNF-␣ and IFN-␥, which in synergy induce apoptotic signalling cascades. A second theory implies that apoptosis is induced by Fas/Fas-ligand interaction and the perforin granzyme system. Other studies reported the immunosuppressive role of some cytokines, such as IL-10 and TGF-␤ which increasing with ageing tend to suppress the cell-mediated activity, needed to control tumor growth and to destroy tumor cells [156]. An other pro-inflammatory cytokines over-expressed in the old people is IL-6, which influences the tumorigenesis mediated by TGF-␤, by increasing the receptor of this last cytokine [156]. In conclusion the knowledge of alterations consistent with aging could influence the enhanced quality of life and life-span in this people. The immunosenescence is associated with a dramatic reduction in responsiveness as well as functional deregulation which contributes to the increased incidence among the older people of morbidity and mortality from infectious disease and cancer. Since the carcinogenesis is an extremely complex phenomenon, it is very difficult to establish the exact role of the immunosenescence. Future studies and continuous effort in this field will help us to break off the vicious cycle that leads to large oligoclonal populations of dysfunctional cells and to restore a good function of the immune system in the

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elderly people. The elucidation and understating the links between innate and adaptive immunity in the regulation of cancer development will offer new therapeutics pathways to develop the most optimal immunotherapeutic strategies that can lead to total tumor eradication.

Reviewers Prof. Salvatore Musumeci, University of Sassari, Department of Pediatrics, Viale San Pietro 12, I-07100 Sassari, Italy. Prof. Pierre-Yves Dietrich, University Hospital of Geneva, Department of Oncology, Rue Micheli-du-Crest, CH-1211 Geneva 14, Switzerland. Dr. Anis Larbi, University of Tübingen, Centre for Medical Research, Tübingen, Germany.

References [1] National Cancer Institute - SEER Cancer Statistics Review 1975–2005. [2] Malaguarnera M, Laurino A, Di Mauro S, Motta M, Di Fazio I, Maugeri D. The comorbidities of elderly oncologic patients. Arch Gerontol Geriatr 2000;30:237–44. [3] Finkel T, Serrano M, Blasco MA. The common biology of cancer and ageing. Nature 2007;448:767–74. [4] Hanahan D, Weinberg RA. The hallmarks of cancer. Cell 2000;100(1):57–70. [5] Murasko DM, Nelson BJ, Silver R, Matour D, Kaye D. Immunologic response in an elderly population with a mean age of 85. Am J Med 1986;81(4):612–8. [6] Franceschi C, Monti D, Barbieri D, et al. Immunosenescence in humans: deterioration or remodelling? Int Rev Immunol 1995;12(1):57–74. [7] Sansoni P, Vescovini R, Fagnoni F, et al. The immune system in extreme longevity. Exp Gerontol 2008;43(2):61–5. [8] Cambier J. Immunosenescence: a problem of lymphopoiesis, homeostasis, microenvironment, and signaling. Immunol Rev 2005;205:5–6. [9] Franceschi C, Bonafe M, Valensin S, et al. Inflamm-aging. An evolutionary perspective on immunosenescence. Ann NY Acad Sci 2000;908:244–54. [10] Derhovanessian E, Solana R, Larbi A, Pawelec G. Immunity ageing and cancer. Immun Ageing 2008;5:11. [11] Potestio M, Pawelec G, Di Lorenzo G, et al. Age-related changes in the expression of CD95 (APO1/FAS) on blood lymphocytes. Exp Gerontol 1999;34:659–73. [12] Powers DC. Effect of age on serum immunoglobulin G subclass antibody responses to inactivated influenza virus vaccine. J Med Virol 1994;43:57–61. [13] Adibzadeh M, Mariani E, Bartoloni C, et al. Lifespans of T lymphocytes. Mech Ageing Dev 1996;91:145–54. [14] Gruver AL, Hudson LL, Sempowski GD. Immunosenescence of ageing. J Pathol 2007;211:144–56. [15] Miller JP, Allman D. Linking age-related defects in B lymphopoiesis to the aging of hematopoietic stem cells. Semin Immunol 2005;17(5):321–9. [16] Nilsson-Ehle H, Swolin B, Westin J. Bone marrow progenitor cell growth and karyotype changes in healthy 88-year-old subjects. Eur J Haematol 1995;55:14–8.

56

L. Malaguarnera et al. / Critical Reviews in Oncology/Hematology 74 (2010) 40–60

[17] Ogawa T, Kitagawa M, Hirokawa K. Age-related changes of human bone marrow: a histometric estimation of proliferative cells, apoptotic cells, T cells, B cells and macrophages. Mech Ageing Dev 2000;117:57–68. [18] Xing Z, Ryan MA, Daria D, et al. Increased hematopoietic stem cell mobilization in aged mice. Blood 2006;108:2190–7. [19] Rando TA. Stem cells, ageing and the quest for immortality. Nature 2006;441(7097):1080–6. [20] Linton PJ, Dorshkind K. Age-related changes in lymphocyte development and function. Nat Immunol 2004;5:133–9. [21] Cancro MP, Allman DM, Hayes CE, et al. B cell maturation and selection at the marrow-periphery interface. Immunol Res 1998;17:3–11. [22] Guerrettaz LM, Johnson SA, Cambier JC. Acquired hematopoietic stem cell defects determine B-cell repertoire changes associated with aging. Proc Natl Acad Sci U S A 2008;105(33):11898–902. [23] Geiger H, Van Zant G. The aging of lympho-hematopoietic stem cells. Nat Immunol 2002;3:329–33. [24] Morrison SJ, Wandycz AM, Akashi K, Globerson A, Weissman IL. The aging of hematopoietic stem cells. Nat Med 1996;2:1011–6. [25] Rossi DJ, Bryder D, Zahn JM, et al. Cell intrinsic alterations underlie hematopoietic stem cell aging. Proc Natl Acad Sci USA 2005;102:9194–9. [26] Janzen V, Forkert R, Fleming HE, et al. Stem-cell ageing modified by the cyclin-dependent kinase inhibitor p16INK4a. Nature 2006;443:421–6. [27] Colonna-Romano G, Bulati M, Aquino A, et al. B cell immunosenescence in the elderly and in centenarians. Rejuvenation Res 2008;11(2):433–9. [28] Franceschi C, Valensis S, Fagnoni S, Barbi C, Bonafe M. Biomarkers of immunosenescence within an evolutionary perspective: the challenge of heterogenicity and the role of antigenic load. Exp Gerontol 1999;34:911–21. [29] Colonna-Romano G, Bulati M, Aquino A, et al. B-cell in the aged: CD27, CD5, and CD40 expression. Mech Ageing Dev 2003;124:389–93. [30] Weksler ME. Changes in the B-cell repertoire with age. Vaccine 2000;18:1624–8. [31] Hu A, Ehleiter D, Ben-Yeuda A. Effect of age on the expressed B cell repertoire: role of B cell subsets. Int Immunol 1993;5:1035–9. [32] Nicoletti C. Antibody protection in aging: influence of idiotypic repertoire and antibody binding activity to a bacterial antigen. Exp Mol Pathol 1995;62:99–108. [33] Johnson SA, Rozzo SJ, Cambier JC. Aging-dependent exclusion of antigen inexperienced cells from the peripheral B cell repertoire. J Immunol 2002;168:5014–23. [34] Sailey RW, Eun SY, Russell CE, Vogel LA. B cells of aged mice show decreased expansion in response to antigen, but are normal in effector function. Cell Immunol 2001;214:99. [35] Min H, Montecino-Rodriguez E, Dorshkind K. Effects of aging on the common lymphoid progenitor to Pro-B cell transition. J Immunol 2006;176:1007–12. [36] Johnson KM, Owen K, Witte PL. Aging and developmental transitions in the B cell lineage. Int Immunol 2002;14:1313–23. [37] Labrie JE, Sah AP, Allman DM, Cancro MP, Gerstein RM. Bone marrow micro-environmental changes underlie reduced RAG-mediated recombination and B cell generation in aged mice. J Exp Med 2004;200:411–23. [38] Riley RL, Van der Put E, King AM, Frasca D, Blomberg BB. Deficient B lymphopoiesis in murine senescence: potential roles for dysregulation of E2A, Pax-5, and STAT5. Semin Immunol 2005;17(5):330–6. [39] Zheng B, Han S, Takahashi Y, Kelsoe G. Immunosenescence and germinal center reaction. Immunol Rev 1997;160:63–77. [40] Nicoletti C, Yang X, Cerny J. Repertoire diversity of antibody response to bacterial antigens in aged mice. III. Phosphorylcholine antibody from young and aged mice differ in structure and protective activity against infection with Streptococcus pneumoniae. J Immunol 1993;150:543–9.

[41] Yang X, Stedra J, Cerny J. Relative contribution of T and B cells to hypermutation and selection of the antibody repertoire in germinal centres of aged mice. J Exp Med 1996;183(3):959–70. [42] Lazuardi L, Jenewein B, Wolf AM, Pfister G, Tzankov A, GrubeckLoebenstein B. Age-related loss of naïve T cells and dysregulation of T cell/B cell interactions in human lymph nodes. Immunology 2005;114(1):37–43. [43] Kim R, Emi M, Tanabe K. Cancer immunoediting from immune surveillance to immune escape. Immunology 2007;121:1–14. [44] Koebel CM, Vermi W, Swann JB, et al. Adaptive immunity maintains occult cancer in an equilibrium state. Nature 2007;450(7171):903–7. [45] Mauro C, Zazzeroni F, Papa S, Bubici C, Franzoso G. The NFkappaB transcription factor pathway as a therapeutic target in cancer: methods for detection of NF-kappaB activity. Methods Mol Biol 2009;512:169–207. [46] Allavena P, Sica A, Solinas G, Porta C, Mantovani A. The inflammatory micro-environment in tumor progression: the role of tumor-associated macrophages. Crit Rev Oncol Hematol 2008;66:1–9. [47] Lai P, Rabinowich H, Crowley-Nowick PA, Bell MC, Mantovani G, Whiteside TL. Alterations in expression and function of signaltransducing proteins in tumor-associated T and natural killer cells in patients with ovarian carcinoma. Clin Cancer Res 1996;2:161–73. [48] Mizoguchi H, O’Shea JJ, Longo DL, Loeffler CM, McVicar DW, Ochoa AC. Alterations in signal transduction molecules in T lymphocytes from tumor-bearing mice. Science 1992;258(5089):1795–8. [49] Rabinowich H, Banks M, Reichert TE, Logan TF, Kirkwood JM, Whiteside TL. Expression and activity of signaling molecules in T lymphocytes obtained from patients with metastatic melanoma before and after interleukin 2 therapy. Clin Cancer Res 1996;2:1263–74. [50] Rabinowich H, Reichert TE, Kashii Y, Bell MC, Whiteside TL. Lymphocyte apoptosis induced by Fas ligand-expressing ovarian carcinoma cells: implications for altered expression of TCR in tumour-associated lymphocytes. J Clin Invest 1998;101:2579–88. [51] Sheu BC, Lin RH, Lien HC, Ho HN, Hsu SM, Huang SC. Predominant Th2/Tc2 polarity of tumor-infiltrating lymphocytes in human cervical cancer. J Immunol 2001;167:2972–8. [52] Sheu BC, Lin RH, Ho HN, Huang SC. Down-regulation of CD25 expression on the surface of activated tumor-infiltrating lymphocytes in human cervical carcinoma. Hum Immunol 1997;56:39–48. [53] Sheu BC, Lien HC, Ho HN, et al. Increased expression and activation of gelatinolytic matrix metalloproteinases is associated with the progression and recurrence of human cervical cancer. Cancer Res 2003;63:6537–42. [54] Kolenko V, Wang Q, Riedy MC, et al. Tumor-induced suppression of T lymphocyte proliferation coincides with inhibition of Jak3 expression and IL-2 receptor signaling: role of soluble products from human renal cell carcinomas. J Immunol 1997;159:3057–67. [55] Harris AL. Hypoxia—a key regulatory factor in tumour growth. Nat Rev Cancer 2002;2:38–47. [56] Youssef MM, Symonds P, Ellis IO, Murray JC. EMAP-II-dependent lymphocyte killing is associated with hypoxia in colorectal cancer. Br J Cancer 2006;95:735–43. [57] Gastman BR, Johnson DE, Whiteside TL, Rabinowich H. Tumorinduced apoptosis of T lymphocytes: elucidation of intracellular apoptotic events. Blood 2000;95:2015–23. [58] Malaguarnera L, Cristaldi E, Vinci M, Malaguarnera M. The role of exercise on the innate immunity of the elderly. Eur Rev Aging Phys Act 2008;5:43–9. [59] Malaguarnera L, Cristaldi E, Lipari H, Malaguarnera M. Acquired immunity: immunosenescence and physical activity. Eur Rev Aging Phys Act 2008;5(2):61–8. [60] Gupta S. Tumor necrosis factor-alpha-induced apoptosis in T cells from aged humans: a role of TNFR-I and downstream signaling molecules. Exp Gerontol 2002;37:293–9. [61] McLeod JD. Apoptotic capability in ageing T cells. Mech Ageing Dev 2000;121(1-3):151–9.

L. Malaguarnera et al. / Critical Reviews in Oncology/Hematology 74 (2010) 40–60 [62] Malaguarnera L, Ferlito L, Di Mauro S, Imbesi RM, Scalia G, Malaguarnera M. Immunosenescence and cancer: a review. Arch Gerontol Geriatr 2001;32(2):77–93. [63] Norian LA, Allen PM. No intrinsic deficiencies in CD8+ T cell-mediated antitumor immunità with aging. J Immunol 2004;173:835–44. [64] Effros RB. Long-term immunological memory against viruses. Mech Ageing Dev 2000;121:161–71. [65] Effros RB. Immune system activity. Handbook of the biology of ageing. 5th ed. San Diego: Academic Press; 2001. [66] Beverley PC, Grubeck-Loebenstein B. Is immune senescence reversible? Vaccine 2000;18:1721–4. [67] Ku CC, Murakami M, Sakamoto A, Kappler J, Marrack P. Control of homeostasis of CD8 memory T cells by opposing cytokines. Science 2000;288:675–8. [68] Spaulding C, Guo W, Effros RB. Resistance to apoptosis in human CD8+ T cells that reach replicative senescence after multiple rounds of antigen-specific proliferation. Exp Gerontol 1999;34: 633–44. [69] Krieger NR, Yin DP, Garrison Fathman C. CD4+ but not CD8+ cells are essential for allo-rejection. J Exp Med 1996;184:2013–8. [70] Shearer GM. Th1/Th2 changes in aging. Mech Ageing Dev 1997;94:1–5. [71] Rink L, Cakman I, Kirchner H. Altered cytokine production in the elderly. Mech Ageing Dev 1998;102:199–209. [72] Wing K, Suri-Payer E, Rudin A. CD4+ CD25+ - regulatory T cells from mouse to man. Scand J Immunol 2005;62(1):1–15. [73] Sakaguchi S, Takahashi T, Yamazaki S, et al. Immunologic self tolerance maintained by T-cell-mediated control of self reactive T cells: implications for autoimmunity and tumor immunity. Microb Infect 2001;3:911–8. [74] Belkaid Y, Rouse BT. Natural regulatory T cells in infectious disease. Nat Immunol 2005;6(4):353–60. [75] Toda A, Piccirillo CA. Development and function of naturally occurring CD4+ CD25+ regulatory T cells. J Leukoc Biol 2006;80(3):458–70. [76] Chattopadhyay S, Chakraborty NG, Mukherji B. Regulatory T cells and tumor immunity. Cancer Immunol Immunother 2005;54:1153–61. [77] Trzonkowski P, Szmit E, Mysliwska J, Mysliwski A. CD4+ CD25+ T regulatory cells inhibit cytotoxic activity of CTL and NK cells in humans—impact of immunosenescence. Clin Immunol 2006;119(3):307–16. [78] Colonna-Romano G, Equino A, Bulati M, et al. Impairment of gamma/delta T lymphocytes in elderly: implications for immunosenescence. Exp Gerontol 2004;39:1439–46. [79] Ferrarini M, Ferrero E, Dagna L, Poggi A, Zocchi MR. Human ␥␦ T cells a non redundant system in the immune-surveillance against cancer. Trends Immunol 2002;23:14–8. [80] Constant P, Davodeau F, Peyrat MA, et al. Stimulation of human gamma delta T cells by non peptidic mycobacterial ligands. Science 1994;264:267–70. [81] Cipriani B, Borsellino G, Poccia F, et al. Activation of C-C beta-chemokines in human peripheral blood gamma-delta T cells by isopentenyl pyrophosphate and regulation by cytokines. Blood 2000;95:39–47. [82] Argentati K, Re F, Donnini A, et al. Numerical and functional alterations of circulating gamma delta T lymphocytes in aged people and centenarians. J Leucoc Biol 2002;72:65–71. [83] Krishnaraj R. Senescence and cytokines modulate the NK cell expression. Mech Ageing Dev 1997;96:89–101. [84] Borrego F, Alonso MC, Galiani MD, et al. NK phenotypic markers and IL2 response in NK cells from elderly people. Exp Gerontol 1999;34:253–65. [85] Kutza J, Murasko DM. Age-associated decline in IL-2 and IL-12 induction of LAK cell activity of human PBMC samples. Mech Ageing Dev 1996;90:209–22.

57

[86] Solana R, Mariani E. NK and NK/T cells in human senescence. Vaccine 2000;18:1613–20. [87] Rabinowich H, Goses Y, Reshef T, Klajman A. Interleukin- 2 production and activity in aged humans. Mech Ageing Dev 1985;32:213–26. [88] Bender BS, Chrest FJ, Adler WH. Phenotypic expression of natural killer cell associated membrane antigens and cytolytic function of peripheral blood cells from different aged humans. J Clin Lab Immunol 1986;21:31–6. [89] Sato T, Fuse A, Kuwata T. Enhancement by IFN of natural cytotoxic activity of lymphocytes from human cord blood and peripheral blood of aged persons. Cell Immunol 1979;45:458–63. [90] Kutza J, Murasko DM. Effects of aging on natural killer cell activity and activation by interleukin-2 and IFN-alpha. Cell Immunol 1994;155:195–204. [91] Argentati K, Bartozzi B, Bernardini G, Di Stasio G, Provinciali M. Induction of NK cell activity and perforin and Granzyme B expression following continuous culture or short pulse with IL-12 in young and old mice. Eur Cytokine Netw 2000;11:59–65. [92] Provinciali M, Di Stefano G, Stronati S, Fabris N. Generation of human lymphokine-activated killer cells following an IL-2 pulse in elderly cancer patients. Cytokine 1998;10(2):132–9. [93] Bykovskaya SN, Abronina IF, Kupriyanova TA, Bubenik J. Downregulation of LAK cell-mediated cytotoxicity: cancer and ageing. Biomed Pharmacother 1990;44:333–8. [94] Lipschitz DA, Udupa KB, Milton KY, Thompson CO. Effect of age on hematopoiesis in man. Blood 1984;63:502–9. [95] Provinciali M, Di Stefano G, Fabris N. Evaluation of LAK cell development in young and old healthy humans. Nat Immun 1995;14:134–44. [96] Mariani E, Pulsatelli L, Meneghetti A, et al. Different IL-8 production by T and NK lymphocytes in elderly subjects. Mech Ageing Dev 2001;122:1383–95. [97] Fabris N, Mocchegiani E, Provinciali M. Plasticity of neuroendocrinethymus interactions during aging. Exp Gerontol 1997;32:415–29. [98] Provinciali M, Fabris, Pieri C. Improvement of natural killer cell activity by in vitro active lipids (AL 721) administration in old mice. Mech Ageing Dev 1990;52:245–54. [99] Imai K, Matsuyama S, Miyake S, Suga K, Nakachi K. Natural cytotoxic activity of peripheral-blood lymphocytes and cancer incidence: an 11-year follow-up study of a general population. Lancet 2000;356:1795–9. [100] Takeuchi H, Maehara Y, Tokunaga E, Koga T, Kakeji Y, Sugimachi K. Ognostic significance of natural killer cell activity in patients with gastric carcinoma: a multivariate analysis. Am J Gastroenterol 2001;96:574–8. [101] Lutz MB, Schuler G. Immature, semi-mature and fully mature dendritic cells: which signals induce tolerance or immunity? Trends Immunol 2002;23(9):445–9. [102] Donnini A, Argentati K, Mancini R, et al. Phenotype antigenpresenting capacity, and migration of antigen-presenting cells in young and old age. Exp Gerontol 2002;37:1097–112. [103] Carrard G, Bulteau AL, Petropoulos I, Friguet B. Impairment of proteasome structure and function in aging. Int J Biochem Cell Biol 2002;34:1461–74. [104] Mishto M, Santoro A, Bellavista E, Bonafe M, Monti D, Franceschi C. Immunoproteasomes and immunosenescence. Ageing Res Rev 2003;2:419–32. [105] Meidenbauer N, Zippelius A, Pittet MJ, et al. High frequency of functionally active Melan-a-specific T cells in a patient with progressive immunoproteasome-deficient melanoma. Cancer Res 2004;64(17):6319–26. [106] Lung TL, Saurwein-Teissl M, Parson W, Schonitzer D, GrubeckLoebenstein B. Unimpaired dendritic cells can be derived from monocytes in old age and can mobilize residual function in senescent T cells. Vaccine 2000;18:1606–12. [107] Miller C, Kelsoe G, Han S. Lack of B7-2 expression in the germinal centers of aged mice. Ageing Immunol Infect Dis 1994;5:249.

58

L. Malaguarnera et al. / Critical Reviews in Oncology/Hematology 74 (2010) 40–60

[108] Akira S, Takeda K, Kaisho T. Toll-like receptors: critical proteins linking innate and acquired immunity. Nat Immunol 2001;2:675–80. [109] Plowden J, Renshaw-Hoelscher M, Engleman C, Katz J, Sambhara S. Innate immunity in aging: impact on macrophage function. Aging Cell 2004;3(4):161–7. [110] Franc NC, White K, Ezekowitz RA. Phagocytosis and development: back to the future. Curr Opin Immunol 1999;11:47–52. [111] Ohashi K, Burkart V, Flohe S, Kolb H. Cutting edge: heat shock protein 60 is a putative endogenous ligand of the toll-like receptor-4 complex. J Immunol 2000;164:558–61. [112] Castle S, Uyemura K, Wong W, Modlin RL, Effros R. Evidence of enhanced type 2 immune response and impaired up-regulation of a type 1 response in frail elderly nursing home residents. Mech Ageing Dev 1997;94:7–16. [113] Lio D, D’Anna C, Gervasi F, et al. Interleukin-12 release by mitogenstimulated mononuclear cells in the elderly. Mech Ageing Dev 1998;102:211–9. [114] Steger MM, Maczek C, Grubeck-Loebenstein B. Morphologically and functionally intact dendritic cells can be derived from the peripheral blood of aged individuals. Clin Exp Immunol 1996;105: 544–50. [115] Sallusto F, Lanzavecchia A. Efficient presentation of soluble antigen by cultured human dendritic cells is maintained by granulocyte/macrophage colony-stimulating factor plus interleukin 4 and downregulated by tumor necrosis factor alpha. J Exp Med 1994;179:1109–18. [116] Della Bella S, Bierti L, Presicce P, et al. Peripheral blood dendritic cells and monocyte are differently regulated in elderly. Clin Immunol 2007;122:220–8. [117] Kiertscher S, Luo J, Dubinett SM, Roth MD. Tumors promote altered maturation and early apoptosis of monocyte-derived dendritic cells. J Immunology 2000;164:1269–76. [118] Alberti S, Cevenini E, Ostan R, et al. Age-dependent modifications of type 1 and type 2 cytokines within virgin and memory CD4+T cells in humans. Mech Ageing Dev 2006;12:560–6. [119] Sadeghi HM, Schnelle JF, Thoma JK, Nishanian P, Fahey JL. Phenotypic and functional characteristics of circulating monocytes of elderly persons. Exp Gerontol 1999;34:959–70. [120] O’Mahony L, Holland J, Jackson J, Feighery C, Hennessy TP, Mealy K. Quantitative intracellular cytokine measurement: agerelated changes in proinflammatory cytokine production. Clin Exp Immunol 1998;113:213–9. [121] Ahluwalia N, Mastro AM, Ball R, Miles MP, Rajendra R, Handte G. Cytokine production by stimulated mononuclear cells did not change with ageing in apparently healthy, well-nourished women. Mech Ageing Dev 2001;122:1269–79. [122] McLachlan JA, Serkin CD, Morrey KM, Bakouche O. Antitumoral properties of aged human monocytes. J Immunol 1995;154: 832–43. [123] Khare V, Sodhi A, Singh SM. Effect of ageing on the tumoricidal functions of murine peritoneal macrophages. Nat Immun 1996;15:285–94. [124] Herrero C, Marques L, Lloberas J, Celada A. IFNgamma-dependent transcription of MHC class II IA is impaired in macrophages from aged mice. J Clin Invest 2001;107:485–93. [125] Renshaw M, Rockwell J, Engleman C, Gewirtz A, Katz J, Sambhara S. Cutting edge: impaired Toll-like receptor expression and function in ageing. J Immunol 2002;169:4697–701. [126] Provinciali M, Smorlesi A. Immunoprevention and immunotherapy of cancer in ageing. Cancer Immunol Immunother 2005;54:93–106. [127] Provinciali M, Argentati K, Tibaldi A. Efficacy of cancer gene therapy in aging: adenocarcinoma cells engineered 103 to release IL-2 are rejected but do not induce tumor specific immune memory in old mice. Gene Ther 2000;7:624–32. [128] Chatta GS, Andrews RG, Rodger E, Schrag M, Hammond WP, Dale DC. Hematopoietic progenitors and ageing: alterations in granulocytic precursors and responsiveness to recombinant human G-CSF, GM-CSF, and IL-3. J Gerontol 1993;48:M207.

[129] Biasi D, Carletto A, Dell’Agnola C, et al. Neutrophil migration, oxidative metabolism, and adhesion in elderly and young subjects. Inflammation 1996;20:673–81. [130] Butcher SK, Chahal H, Nayak L, et al. Senescence in innate immune responses: reduced neutrophil phagocytic capacity and CD16 expression in elderly humans. J Leukoc Biol 2001;70:881–6. [131] Ponnappan U, Zhong M, Trebilcock GU. Decreased proteasomemediated degradation in T cells from the elderly: a role in immune senescence. Cell Immunol 1999;192(2):167–74. [132] Mishto M, Bonafè M, Salvioli S, Olivieri F, Franceschi C. Age dependent impact of LMP polymorphisms on TNFalpha-induced apoptosis in human peripheral blood mononuclear cells. Exp Gerontol 2002;37(2–3):301–8. [133] Frasca D, Scarpaci S, Barattini P, et al. The DNA repair protein ku is involved in gp130-mediated signal transduction events in PBMC from young but not from elderly subjects. Exp Gerontol 2002;37(2–3):321–8. [134] Mariani E, Cattini L, Neri S, et al. Simultaneous evaluation of circulating chemokine and cytokine profiles in elderly subjects by multiplex technology: relationship with zinc status. Biogerontology 2006;7(5–6):449–59. [135] Olivieri F, Bonafè M, Giovagnetti S, et al. In vitro IL-6 production by EBV-immortalized B lymphocytes from young and elderly people genotyped for −174C/G polymorphism in IL-6 gene: a model to study the genetic basis of inflamm-aging. Mech Ageing Dev 2003;124(4):549–53. [136] Airoldi I, Di Carlo E, Cocco C, et al. Lack of Il12rb2 signaling predisposes to spontaneous autoimmunity and malignancy. Blood 2005;106:3846–53. [137] Street SE, Trapani JA, MacGregor D, Smyth MJ. Suppression of lymphoma and epithelial malignancies effected by interferon gamma. J Exp Med 2002;196:129–34. [138] Street SE, Hayakawa Y, Zhan Y, et al. Innate immune surveillance of spontaneous B cell lymphomas by natural killer cells and gammadelta T cells. J Exp Med 2004;199:879–84. [139] Clementi R, Locatelli F, Dupré L, et al. A proportion of patients with lymphoma may harbor mutations of the perforin gene. Blood 2005;105:4424–8. [140] Enzler T, Gillessen S, Manis JP, et al. Deficiencies of GM-CSF and interferon gamma link inflammation and cancer. J Exp Med 2003;197:1213–9. [141] Coussens LM, Werb Z. Inflammation and cancer. Proc Natl Acad Sci USA 2002;20:860–7. [142] Shankaran V, Ikeda H, Bruce AT, et al. IFNgamma and lymphocytes prevent primary tumour development and shape tumour immunogenicity. Proc Natl Acad Sci USA 2001;10:1107–11. [143] Zerafa N, Westwood JA, Cretney E, et al. Cutting edge: TRAIL deficiency accelerates hematological malignancies. J Immunol 2005;175:5586–90. [144] Smyth MJ, Thia KY, Street SE, et al. Perforin-mediated cytotoxicity is critical for surveillance of spontaneous lymphoma. J Exp Med 2000;192:755–60. [145] Ross OA, Hyland P, Curran MD, et al. Mitochondrial DNA damage in lymphocytes: a role in immunosenescence? Exp Gerontol 2002;37(2–3):329–40. [146] Moccheggiani E, Malavolta M. Zinc-gene interaction related to inflammatory/immune response in ageing. Genes Nutr 2008;3(2):61–75. [147] Silva J, Silva JM, Barradas M, et al. Analysis of the candidate tumor suppressor Ris-1 in primary human breast carcinomas. Mutat Res 2006;594(1–2):78–85. [148] García-Cao I, García-Cao M, Martín-Caballero J, et al. “Super p53” mice exhibit enhanced DNA damage response, are tumor resistant and age normally. EMBO J 2002;21(22):6225–35. [149] Hu HL, Forsey RJ, Blades TJ, Barratt ME, Parmar P, Powell JR. Antioxidants may contribute in the fight against ageing: an in vitro model. Mech Ageing Dev 2000;121(1–3):217–30.

L. Malaguarnera et al. / Critical Reviews in Oncology/Hematology 74 (2010) 40–60 [150] Sourlingas TG, Kypreou KP, Sekeri-Pataryas KE. The effect of the histone deacetylase inhibitor, trichostatin A, on total histone synthesis, H1(0) synthesis and histone H4 acetylation in peripheral blood lymphocytes increases as a function of increasing age: a model study. Exp Gerontol 2002;37(2–3):341–8. [151] Fulop T, Dupuis G, Fortin C, Douziech N, Larbi A. T cell response in aging: influence of cellular cholesterol modulation. Adv Exp Med Biol 2006;584:157–69. [152] Fortin CF, Larbi A, Dupuis G, Lesur O, Fülöp Jr T. GM-CSF activates the Jak/STAT pathway to rescue polymorphonuclear neutrophils from spontaneous apoptosis in young but not elderly individuals. Biogerontology 2007;8(2):173–87. [153] Witkowski JM, Bryl E. Paradoxical age-related cell cycle quickening of human CD4(+) lymphocytes: a role for cyclin D1 and calpain. Exp Gerontol 2004;39(4):577–85. [154] Motta M, Ferlito L, Malaguarnera L, et al. Alterations of the lymphocytic set-up in elderly patients with cancer. Arch Gerontol Geriatr 2003;36:7–14. [155] Walker PR, Saas P, Dietrich P-Y. Role of Fas Ligand (CD95L) in immune escape: the tumor cell strikes back. J Immunol 1997;158:4521–4. [156] Zhou D, Chrest FJ, Adler W, Munster A, Winchurch RA. Increased production of TGF-beta and IL-6 by aged spleen cells. Immunol Lett 1993;36:7–11. [157] Goodwin JS, Messner RP. Sensitivity of lymphocytes to prostaglandin E2 increases in subjects over age 70. J Clin Invest 1979;64: 434–9. [158] Chidrawar S, Khan N, Wei W, et al. Cytomegalovirus-seropositivity has a profound influence on the magnitude of major lymphoid subsets within healthy individuals. Clin Exp Immunol 2009;155: 423–32. [159] Zanni F, Vescovini R, Biasini C, et al. Marked increase with age of type 1 cytokines within memory and effector/cytotoxic CD8+T cells in humans: a contribution to understand the relationship between inflammation and immunosenescence. Exp Gerontol 2003;38: 981–7. [160] Lin WW, Karin M. A cytokine-mediated link between innate immunity, inflammation, and cancer. J Clin Invest 2007;117(5):1175–83. [161] Dinarello CA. The paradox of pro-inflammatory cytokines in cancer. Cancer Metastasis Rev 2006;25:307–13. [162] Balkwill F, Charles KA, Mantovani A. Smoldering and polarized inflammation in the initiation and promotion of malignant disease. Cancer Cell 2005;7:211–7. [163] Agarwal A, Verma S, Burra U, Murthy NS, Mohanty NK, Saxena S. Flow cytometric analysis of Th1 and Th2 cytokines in PBMCs as a parameter of immunological dysfunction in patients of superficial transitional cell carcinoma of bladder. Cancer Immunol Immunother 2006;55(6):734–43. [164] Sheu BC, Lin RH, Lien HC, Ho HN, Hsu SM, Huang SC. Predominant Th27Tc2 polarity of tumor-infiltrating lymphocytes in human cervical cancer. J Immunol 2001;167:2972. [165] Woodworth CD, McMullin E, Iglesias M, Plowman GD. Interleukin 1 alpha and tumor necrosis factor alpha stimulate autocrine amphiregulin expression and proliferation of human papillomavirusimmortalized and carcinoma-derived cervical epithelial cells. Proc Natl Acad Sci USA 1995;92(7):2840–4. [166] Arlt A, Vorndamm J, Muerkoster S, et al. Autocrine production of interleukin 1beta confers constitutive nuclear factor kappaB activity and chemoresistance in pancreatic carcinoma cell lines. Cancer Res 2002;62(3):910–6. [167] Saijo Y, Tanaka M, Miki M, et al. Proinflammatory cytokine IL-1 beta promotes tumor growth of Lewis lung carcinoma by induction of angiogenic factors: in vivo analysis of tumor-stromal interaction. J Immunol 2002;169(1):469–75. [168] Lin EY, Nguyen AV, Russell RG, Pallard JW. Colony-stimulating factor 1 promotes progression of mammary tumors to malignancy. J Exp med 2001;193:727–40.

59

[169] Mocellin S, Rossi CR, Pilati P, Nitti D. Tumor necrosis factor, cancer and anticancer therapy. Cytokine Growth Factor Rev 2005;16:35–53. [170] Luo JL, Maeda S, Hsu LC, Yagita H, Karin M. Inhibition of NF-kB in cancer cells converts inflammation-induced tumor growth mediated by TNF-␣ to TRAIL-mediated tumor regression. Cancer Cell 2004;6:297–305. [171] Hussain SP, Hofseth LJ, Harris CC. Radical causes of cancer. Nat Rev Cancer 2003;3:276–85. [172] Elgert KD, Alleva DG, Mullins DW. Tumor-induced immune dysfunction: the macrophage connection. J Leukoc Biol 1998;64: 275–90. [173] Knight B, Yeoh GC, Husk KL, et al. Impaired preneoplastic changes and liver tumor formation in tumor necrosis factor receptor type 1 knockout mice. J Exp Med 2000;192:1809–18. [174] Aggarwal BB, Shishodia S, Sandur SK, Pandey MK, Sethi G. Inflammation and cancer: how hot is the link? Biochemical Pharmacol 2006;72:1605–21. [175] Rose-John S, Scheller J, Elson G, Jones SA. Interleukin-6 biology is coordinated by membrane-bound and soluble receptors: role in inflammation and cancer. J Leukoc Biol 2006;80:227–36. [176] Belardelli F, Ferrantini M, Proietti E, Kirkwood JM. Interferon ␣ in tumor immunity and immunotherapy. Cytokine Growth Factor Rev 2002;13:119–34. [177] Biron CA. Interferons ␣ and ␤ as immune regulators—a new look. Immunity 2001;14:661–4. [178] Moore KW, de Waal Malefyt R, Coffman RL, O’Garra A. Interleukin-10 and the interleukin-10 receptor. Annu Rev Immunol 2001;19:683–765. [179] Hoentjen F, Sartor RB, Ozaki M, Jobin C. STAT3 regulates NFkB recruitment to the IL-12p40 promoter in dendritic cells. Blood 2005;105:689–96. [180] Kundu N, Fulton AM. Interleukin-10 inhibits tumor metastasis, down-regulates MHC class I, and enhances NK lysis. Cell Immunol 1997;180:55–61. [181] Blankenstein T. The role of tumor stroma in the interaction between tumor and immune system. Curr Opin Immunol 2005;17:180–6. [182] Lech-Maranda E, Bienvenu J, Michallet AS, et al. Elevated IL-10 plasma levels correlate with poor prognosis in diffuse large B-cell lymphoma. Eur Cytokine Netw 2006;17:60–6. [183] Ogden CA, Pound JD, Batth BK, et al. Enhanced apoptotic cell clearance capacity and B cell survival factor production by IL10–activated macrophages: implications for Burkitt’s lymphoma. J Immunol 2005;174:3015–23. [184] Sakamoto T, Saito H, Tatebe S, et al. Interleukin-10 expression significantly correlates with minor CD8+ T cell infiltration and high microvessel density in patients with gastric cancer. Int J Cancer 2006;118:1909–14. [185] Mocellin S, Marincola FM, Young HA. Interleukin-10 and the immune response against cancer: a counterpoint. J Leukoc Biol 2005;78:1043–51. [186] Trinchieri G. Interleukin-12 and the regulation of innate resistance and adaptive immunity. Nat Rev 2003;3:133–46. [187] Terabe M, Park JM, Berzofsky JA. Role of IL-13 in regulation of antitumor immunity and tumor growth. Cancer Immunol Immunother 2004;53:79–85. [188] Numasaki M, Watanabe M, Suzuki T, et al. IL-17 enhances the net angiogenic activity and in vivo growth of human non-small cell lung cancer in SCID mice through promoting CXCR-2–dependent angiogenesis. J Immunol 2005;175:6177–89. [189] Numasaki M, Fukushi J, Ono M, et al. Interleukin-17 promotes angiogenesis and tumor growth. Blood 2003;101:2620–727. [190] Kothapalli R, Nyland SB, Kusmartseva I, Bailey RD, McKeown TM, Loughran Jr TP. Constitutive production of proinflammatory cytokines RANTES, MIP-1beta and IL-18 characterizes LGL leukaemia. Int J Oncol 2005;26(2):529–35. [191] Hao JS, Shan BE. Immune enhancement and anti-tumour activity of IL-23. Cancer Immunol Immunother 2006;55:1426–31.

60

L. Malaguarnera et al. / Critical Reviews in Oncology/Hematology 74 (2010) 40–60

[192] Langowski JL, Zhang X, Wu L, et al. IL-23 promotes tumour incidence and growth. Nature 2006;442:461–5. [193] Baggiolini M, Dewald B, Moser B. Human chemokines: an update. Annu Rev Immunol 1997;15:675–705. [194] Bazan JF, Bacon KB, Hardiman G. A new class of membrane bound chemokine with a CX3C motif. Nature 1997;385:640–4. [195] Garcia-Zepeda EA, Combadiere C, Rothenberg ME. Human monocyte chemoattractant protein (MCP)-4 is a novel CC chemokine with activities on monocytes, eosinophils, and basophils induced in allergic and non-allrgic inflammation that signals through the CC chemokine receptors (CCR)-2 and 3. J Immunol 1996;157:5613–26. [196] Luboshits G, Shina S, Kaplan O. Elevated expression of the CC Chemokine regulated on activation, normal T cell expressed and secreted (RANTES) in advanced breast carcinoma. Cancer Res 1999;59:4681–7. [197] Mo R, Chen J, Han Y, et al. T cell chemokine receptor expression in aging. J Immunol 2003;170:895–904. [198] Sallusto F, Lenig D, Forster R, Lipp M, Lanzavecchia A. Two subsets of memory T lymphocytes with distinct homing potentials and effector function. Nature 1999;401:708. [199] Wolf M, Albrecht S, Märki C. Proteolytic processing of chemokines: implications in physiological and pathological conditions. Int J Biochem Cell Biol 2008;40(6-7):1185–98. [200] Mule JJ, Custer M, Averbook B, et al. RANTES secretion by gene-modified tumor cells results in loss of tumorigenicity in vivo: role of immune cell subpopulations. Hum Gene Ther 1996;7: 1545–53. [201] Tang KF, Tan SY, Chan SH, et al. A distinct expression of CC chemokines by macrophages in nasopharyngeal carcinoma: implication for the intense tumor infiltration by T lymphocytes and macrophages. Hum Pathol 2001;32:42–9. [202] Negus RP, Stamp GW, Hadley J, Balkwill FR. Quantitative assessment of the leukocyte infiltrate in ovarian cancer and its relationship to the expression of CC chemokines. Am J Pathol 1997;150:1723–34. [203] Pertl U, Luster AD, Varki NM, et al. IFN-␥ inducible protein-10 is essential for the generation of a protective tumor-specific CD8 T cell response induced by single-chain IL-12 gene therapy. J Immunol 2001;166:6944–51. [204] Cairns CM, Gordon JR, Li F, Baca-Estrada ME, Moyana T, Xiang J. Lymphotactin expression by engineered myeloma cells drives tumor regression: mediation by CD4(+) and CD8(+) T cells and neutrophils expressing XCR1 receptor. J Immunol 2001;167:57–65. [205] Irmiger-Finger I. Science of cancer and aging. J Clin Oncol 2007;25:1844–51.

[206] Warner HR, Hodes RJ, Pocinki K. What does cell death have to do with aging? J Am Gertiatr Soc 1997;45:1140–6. [207] Krtolica A, Parrinello S, Lockett S, Desprez PY, Campisi J. Senescent fibroblasts promote epithelial cell growth and tumorogenesis: a link between cancer and aging. Proc Natl Acad Sci USA 2001;98:12072–7. [208] Hockenbery D, Nunez C, Milliman C, Schreiber RD, Korsmeyer SJ. Bcl2 is an inner mitochondrial membrane protein that blocks programmed cell death. Nature 1990;348:334–6.

Biographies Lucia Malaguarnera was a postdoctoral fellow at the Thomas Jefferson Cancer Institute, Philadelphia, USA, where she studied the regulation of normal hematopoiesis and the mechanisms of abnormal growth in leukemic cells. Her postgraduate research was in clinical biology and oncology. Currently she is an Associated Professor of General Pathology at Catania University, School of Medicine. Her research interests include the molecular mechanisms involved in degenerative diseases and cancerogenesis. Erika Cristaldi was born in Catania on the 26th of September 1981. She has taken a degree inmedicine and surgery on 21th of December 2006 in Catania University. She is studying at the geriatric medical school of Catania University the complications of oncological elderly patients. Mariano Malaguarnera is an associate professor at the department of internal medicine and geriatrics, Catania University, Italy. He is a specialist in haematology, respiratory diseases and internal medicine. Since February 2008 he is the director of the Geriatric and Gerontology School in Catania University. At Cannizzaro hospital he is the head of the oncologial unit. He has published numerous scientific articles on metabolism, liver disease, geriatric and oncology; he holds the post of oncology and geriatric at the medical school of Catania University.