Aging and the dendritic cell system: implications for cancer

Cellular senescence and metabolic reprogramming: Unraveling the intricate crosstalk in the immunosuppressive tumor microenvironment

The intrinsic oncogenic mechanisms and properties of the tumor microenvironment (TME) have been extensively investigated. Primary features of the TME include metabolic reprogramming, hypoxia, chronic inflammation, and tumor immunosuppression. Previous studies suggest that senescence-associated secretory phenotypes that mediate intercellular information exchange play a role in the dynamic evolution of the TME. Specifically, hypoxic adaptation, metabolic dysregulation, and phenotypic shifts in immune cells regulated by cellular senescence synergistically contribute to the development of an immunosuppressive microenvironment and chronic inflammation, thereby promoting the progression of tumor events. This review provides a comprehensive summary of the processes by which cellular senescence regulates the dynamic evolution of the tumor-adapted TME, with focus on the complex mechanisms underlying the relationship between senescence and changes in the biological functions of tumor cells. The available findings suggest that components of the TME collectively contribute to the progression of tumor events. The potential applications and challenges of targeted cellular senescence-based and combination therapies in clinical settings are further discussed within the context of advancing cellular senescence-related research.

Immunotherapy in Older Patients with Cancer: A Narrative Review

Purpose

Immunotherapies have revolutionized cancer treatment; however, relatively little is known about their efficacy and toxicity in the elderly, a cohort accounting for more than half of total cancer cases. In this review, we aim to provide insight into the current knowledge base regarding the clinical utility and side effects of immunotherapies in the geriatric population as well as identify key gaps in the literature where further research is essential.

Methods

We conducted a rapid critical review of available literature, focusing on studies reporting on use of immunotherapy in cancer patients aged ≥65 years. The review assessed studies that included different types of cancer, were of multiple study types (although predominantly retrospective), had different study duration, and reported different outcomes of interest. Owing to this heterogeneity, meta-analysis and a direct comparison between studies were not feasible.

Results

Overall, the review findings indicate that certain malignancies have shown comparable survival rates in younger and older age groups when managed with immunotherapeutic drugs, the incidence of immunotherapy-related side effects varies only slightly by age groups, and in general there is a lack of studies on the determinants of the clinical outcomes of immunotherapy in or including geriatric patients.

Conclusion

Enhanced clinical benefits along with better tolerability associated with immunotherapies make it an attractive alternative to conventional chemotherapeutic drugs, especially in elderly patients. There is currently a limited number of studies assessing the clinical outcomes of immunotherapies, particularly in the elderly. Overall, our findings reflect a need for further prospective studies focussing on geriatric patients representative of the real-life population, in order to derive a more precise understanding of the clinical utility, toxicity profile, and cost-effectiveness of immune checkpoint inhibitors in older patients with cancer.

Differences in the post-stroke innate immune response between young and old

Aging is associated to progressive changes impairing fundamental cellular and tissue functions, and the relationships amongst them through the vascular and immune systems. Aging factors are key to understanding the pathophysiology of stroke since they increase its risk and worsen its functional outcome. Most currently recognised hallmarks of aging are also involved in the cerebral responses to stroke. Notably, age-associated chronic low-grade inflammation is related to innate immune responses highlighted by induction of type-I interferon. The interferon program is prominent in microglia where it interrelates cell damage, danger signals, and phagocytosis with immunometabolic disturbances and inflammation. Microglia engulfment of damaged myelin and cell debris may overwhelm the cellular capacity for waste removal inducing intracellular lipid accumulation. Acute inflammation and interferon-stimulated gene expression are also typical features of acute stroke, where danger signal recognition by microglia trigger immunometabolic alterations underscored by lipid droplet biogenesis. Aging reduces the capacity to control these responses causing increased and persistent inflammation, metabolic dysregulation, and impaired cellular waste disposal. In turn, chronic peripheral inflammation during aging induces immunosenescence further worsening stroke-induced immunodepression, thus increasing the risk of post-stroke infection. Aging also alters gut microbiota composition inducing dysbiosis. These changes are enhanced by age-related diseases, such as atherosclerosis and type-II diabetes, that further promote vascular aging, predispose to stroke, and exacerbate brain inflammation after stroke. Current advances in aging research suggest that some age-associated alterations may be reversed. Future work will unravel whether such evolving anti-aging research may enable designing strategies to improve stroke outcome in the elderly.

Thymic function and survival at advance ages in nursing home residents from Southern Italy

BACKGROUND

Immunosenescence is a complex process characterized by an age-related remodelling of immune system. The prominent effects of the immunosenescence process is the thymic involution and, consequently, the decreased numbers and functions of T cells. Since thymic involution results in a collapse of the T-cell receptor (TCR) repertoire, a reliable biomarker of its activity is represented by the quantification of signal joint T-cell receptor rearrangement excision circles (sjTRECs) levels. Although it is reasonable to think that thymic function could play a crucial role on elderly survival, only a few studies investigated the relationship between an accurate measurement of human thymic function and survival at old ages.

METHODS AND FINDINGS

By quantifying the amount sjTRECs by real-time polymerase chain reaction (PCR), the decrease in thymic output in 241 nursing home residents from Calabria (Southern Italy) was evaluated to investigate the relationship between thymic function and survival at old ages. We found that low sjTREC levels were associated with a significant increased risk of mortality at older ages. Nursing home residents with lower sjTREC exhibit a near 2-fold increase in mortality risk compared to those with sjTREC levels in a normal range.

CONCLUSION

Thymic function failure is an independent predictor of mortality among elderly nursing home residents. sjTREC represents a biomarker of effective ageing as its blood levels could anticipate individuals at high risk of negative health outcomes. The identification of these subjects is crucial to manage older people's immune function and resilience, such as, for instance, to plan more efficient vaccinal campaigns in older populations.

Contributions of cancer treatment, comorbidities, and obesity to aging-related disease risks among non-Hodgkin lymphoma survivors

PURPOSE

It is unknown whether cancer treatment contributes more to long-term disease risk than lifestyle factors and comorbidities among B-cell non-Hodgkin lymphoma (B-NHL) survivors.

METHODS

B-NHL survivors were identified in the Utah Cancer Registry from 1997 to 2015. Population attributable fractions (PAF) were calculated to assess the role of clinical and lifestyle factors for six cardiovascular, pulmonary, and renal diseases.

RESULTS

Cancer treatment contributed to 11% of heart and pulmonary conditions and 14.1% of chronic kidney disease. Charlson Comorbidity Index (CCI) at baseline contributed to all six diseases with a range of 9.9% of heart disease to 26.5% of chronic kidney disease. High BMI at baseline contributed to 18.4% of congestive heart failure and 7.9% of pneumonia, while smoking contributed to 4.8% of COPD risk.

CONCLUSION

Cancer treatment contributed more to heart disease, COPD, and chronic kidney disease than lifestyle factors and comorbidities among B-NHL survivors. High BMI at baseline contributed more to congestive heart failure and pneumonia than cancer treatment, whereas smoking at baseline was not a major contributor in this B-NHL survivor cohort. Baseline comorbidities consistently demonstrated high attributable risks for these diseases, demonstrating a strong association between preexisting comorbidities and aging-related disease risks.

Distribution of DC Subtypes: CD83+, DC-LAMP+, CD1a+, CD1c+, CD123+, and DC-SIGN+ in the Tumor Microenvironment of Endometrial Cancers-Correlation with Clinicopathologic Features

Treatment options for endometrial cancer (EC) do not provide satisfactory survival improvement for advanced cases, hence the interest in novel therapies utilizing immunological regulatory mechanisms. Measures to modify the functionality of dendritic cells (DCs) found in TME are intensively investigated, given that DCs play a crucial role in inducing antitumor immunity. Samples of malignant endometrial neoplasms obtained from 94 patients were immunohistochemically stained with selected antibodies. Counts of positively identified DCs were correlated with clinical advancement and histological malignancy of cancers. The most prominent DC subtypes were immature DC-SIGN+ or CD123+. Mature CD83+ DCs were the fewest. We found a significant divergence of grade value distribution between cancers of different DCs' CD1a+ counts. The DC-LAMP+ count was positively associated with grade. Cancers with the least DC CD1c+ or DC CD123+ had higher pT scores than ones that were more heavily infiltrated. ECs can suppress immune cells, hence the predominance of immature DCs in our samples. Associations between DC counts and clinicopathological features of EC were observed only for a few subsets, which was plausibly due to the low diversity of the obtained samples or the small group size. Predictive abilities of particular DC immune subsets within EC's TME remain ambiguous, which calls for further research.

Age-Related Disease Risks in Younger versus Older B-Cell Non-Hodgkin's Lymphoma Survivors

BACKGROUND

Younger cancer survivors may develop age-related diseases due to the cancer treatment that they undergo. The aim of this population-based study is to estimate incidence of age-related diseases besides cardiovascular disease among younger versus older B-cell non-Hodgkin's lymphoma (B-NHL) survivors compared with their respective general population cohorts.

METHODS

Survivors of B-NHL were diagnosed between 1997 and 2015 from the Utah Cancer Registry. Using the Utah Population Database, up to 5 cancer-free individuals from the general population were matched with a B-NHL survivor on sex, birth year, and state of birth. Hazard ratios (HR) for age-related disease outcomes, which were identified from medical records and statewide health care facility data, were estimated using Cox Proportional Hazards models for B-NHL survivors diagnosed at <65 years versus ≥65 years at least 5 years since B-NHL diagnosis.

RESULTS

Comparing 2,129 B-NHL survivors with 8,969 individuals from the general population, younger B-NHL survivors had higher relative risks of acute renal failure [HR, 2.24; 99% confidence interval (CI), 1.48-3.39; P heterogeneity = 0.017), pneumonia (HR, 2.42; 99% CI, 1.68-3.49; P heterogeneity = 0.055), and nutritional deficiencies (HR, 2.08; 99% CI, 1.48-2.92; P heterogeneity = 0.051) ≥5 years after cancer diagnosis.

CONCLUSION

Younger B-NHL survivors had higher relative risks of acute renal failure, pneumonia, and nutritional deficiencies than older B-NHL survivors compared with their respective general population cohorts, ≥5 years after cancer diagnosis.

No Effect of Acute Eccentric Resistance Exercise on Immune Responses to Influenza Vaccination in Older Adults: A Randomized Control Trial

INTRODUCTION

Older adults are at elevated risk for morbidity and mortality caused by influenza. Vaccination is the primary means of prophylaxis, but protection is often compromised in older adults. As resistance exercise mobilizes immune cells into muscle, it may enhance vaccination response.

PURPOSE

Compare antibody and cell mediated immune responses to influenza vaccination in older adults who performed eccentric resistance exercise immediately prior to vaccination to those who did not exercise.

METHODS

Twenty nine resistance training-naive older adults (20 women, 73.9 ± 5.3 years) were randomized to 1 of 3 groups: vaccination in the same arm that exercised (Ex-S), vaccination in the opposite arm that exercised (Ex-Op), and seated rest (No-Ex). Exercise consisted of 10 sets of 5 eccentric unilateral repetitions at 80% of the pre-determined concentric one repetition maximum. Lateral raises were alternated with bicep curls. No-Ex sat quietly for 25 min. Following exercise or rest, all received the 2018 quadrivalent influenza vaccine (Seqirus Afluria) in the non-dominant deltoid. Antibody titers against each influenza vaccine strain were determined by hemagglutinin inhibition assays at baseline, 6-, and 24-weeks post-vaccination. Influenza-specific T cells were quantified after stimulation with the vaccine by intracellular cytokine staining.

RESULTS

No significant group x time effects were found in antibody responses to any strain (interaction for A/H1N1: p = 0.682; A/H3N2: p = 0.644; B/Colorado/06/2017: p = 0.262; B/Phuket/3073/2013: p = 0.851). Groups did not differ in fold-increase of antibody titers 6- and 24-weeks post-vaccination. Influenza-specific T-cells did not differ between groups at any time (comparison at baseline: p = 0.985; 6-weeks: p = 0.889; 24 weeks: p = 0.857). One subject (Ex-S) reported flu-like symptoms 18 weeks post-vaccination.

CONCLUSION

Acute arm eccentric exercise did not influence antibody titers or cell mediated immune responses to the influenza vaccine delivered post-exercise in older adults. More strenuous exercise may be required for exercise to act as an adjuvant. ClinicalTrials.gov Identifier: NCT03736759.

Porphyromonas gingivalis Provokes Exosome Secretion and Paracrine Immune Senescence in Bystander Dendritic Cells

Periodontitis is a disease of ageing or inflammaging, and is comorbid with other more severe age-related chronic diseases. With advanced age comes an increase in accumulation of senescent cells that release soluble and insoluble pro-inflammatory factors collectively termed the senescence associated secretory phenotype (SASP). In the present report, we examined whether immune cells typical of those at the oral mucosa-microbe interface, are vulnerable to cellular senescence (CS) and the role of dysbiotic oral pathogen Porphyromonas gingivalis. Bone marrow-derived dendritic cells (DCs) from young (yDCs) and old (oDCs) mice were co-cultured in vitro with CS inducer doxorubicin or P.gingivalis (Pg), plus or minus senolytic agent rapamycin. CS profiling revealed elevated CS mediators SA-β-Gal, p16 ^INK4A, p53, and p21^Waf1/Clip1 in oDCs, or yDCs in response to doxorubicin or P. gingivalis, reversible with rapamycin. Functional studies indicate impaired maturation function of oDCs, and yDC exposed to P. gingivalis; moreover, OVA-driven proliferation of CD4+ T cells from young OTII transgenic mice was impaired by oDCs or yDCs+Pg. The SASP of DCs, consisting of secreted exosomes and inflammasome-related cytokines was further analyzed. Exosomes of DCs cocultured with P. gingivalis (PgDCexo) were purified, quantitated and characterized. Though typical in terms of size, shape and phenotype, PgDCexo were 2-fold greater in number than control DCs, with several important distinctions. Namely, PgDCexo were enriched in age-related miRNAs, and miRNAs reported to disrupt immune homeostasis through negative regulation of apoptosis and autophagy functions. We further show that PgDCexo were enriched in P. gingivalis fimbrial adhesin protein mfa1 and in inflammasome related cytokines IL-1β, TNFα and IL-6. Functionally PgDCexo were readily endocytosed by recipient yDCs, amplifying functional impairment in maturation and ability to promote Ova-driven proliferation of OTII CD4+ T cells from young mice. In conclusion P. gingivalis induces premature (autocrine) senescence in DCs by direct cellular invasion and greatly amplifies senescence, in paracrine, of bystander DCs by secretion of inflammatory exosomes. The implications of this pathological pathway for periodontal disease in vivo is under investigation in mouse models.

Alterations in composition of immune cells and impairment of anti-tumor immune response in aged oral cancer-bearing mice

OBJECTIVES

Aging has been suggested to be associated with immune dysregulation. An understanding of alterations in the host immunity with advancing age is, therefore, important for designing immune therapy for elderly cancer patients. In this context, not much is known about age-associated alterations in the immune system in oral cancer.

METHODS

To evaluate age-associated alterations in the immune system, which might affect anti-tumor immune responses in oral cancer, we performed a comparative analysis of the proportion of different immune cells, the proliferative capacity of T cell compartment, and the response against immune therapies targeting immune check point molecules between young and aged oral cancer-bearing mice.

RESULTS

The proportion of immune regulatory cells, such as regulatory T cells and myeloid derived suppressor cells, was significantly increased in aged mice compared to that in young mice. Moreover, the expression of PD-1 and CTLA-4 on both CD4⁺ and CD8⁺ T cells was elevated in aged mice compared to that in young mice, and the proliferative abilities of CD4⁺ and CD8⁺ T cells derived from aged mice were significantly reduced following stimulation of T-cell receptors. Moreover, tumor growth was significantly enhanced in aged mice compared to that in young mice. However, immunotherapies targeting PD-1, CTLA-4, and PD-L1 resulted in faster tumor regression in aged mice than in young mice.

CONCLUSIONS

Together, our results indicate that age-associated alterations in the immune system are directly associated with the impairment of anti-tumor immunity in aged mice bearing oral cancer, and might facilitate the progression of the tumor.

Immunosenescence: the potential role of myeloid-derived suppressor cells (MDSC) in age-related immune deficiency

The aging process is associated with chronic low-grade inflammation in both humans and rodents, commonly called inflammaging. At the same time, there is a gradual decline in the functional capacity of adaptive and innate immune systems, i.e., immunosenescence, a process not only linked to the aging process, but also encountered in several pathological conditions involving chronic inflammation. The hallmarks of immunosenescence include a decline in the numbers of naïve CD4+ and CD8+ T cells, an imbalance in the T cell subsets, and a decrease in T cell receptor (TCR) repertoire and signaling. Correspondingly, there is a decline in B cell lymphopoiesis and a reduction in antibody production. The age-related changes are not as profound in innate immunity as they are in adaptive immunity. However, there are distinct functional deficiencies in dendritic cells, natural killer cells, and monocytes/macrophages with aging. Interestingly, the immunosuppression induced by myeloid-derived suppressor cells (MDSC) in diverse inflammatory conditions also targets mainly the T and B cell compartments, i.e., inducing very similar alterations to those present in immunosenescence. Here, we will compare the immune profiles induced by immunosenescence and the MDSC-driven immunosuppression. Given that the appearance of MDSCs significantly increases with aging and MDSCs are the enhancers of other immunosuppressive cells, e.g., regulatory T cells (Tregs) and B cells (Bregs), it seems likely that MDSCs might remodel the immune system, thus preventing excessive inflammation with aging. We propose that MDSCs are potent inducers of immunosenescence.

Immunosenescence in neurocritical care

BACKGROUND

Several advanced and developing countries are now entering a superaged society, in which the percentage of elderly people exceeds 20% of the total population. In such an aging society, the number of age-related diseases such as malignant tumors, diabetes, and severe infections including sepsis is increasing, and patients with such disorders often find themselves in the ICU.

MAIN BODY

Age-related diseases are closely related to age-induced immune dysfunction, by which reductions in the efficiency and specificity of the immune system are collectively termed "immunosenescence." The most noticeable is a decline in the antigen-specific acquired immune response. The exhaustion of T cells in elderly sepsis is related to an increase in nosocomial infections after septicemia, and even death over subacute periods. Another characteristic is that senescent cells that accumulate in body tissues over time cause chronic inflammation through the secretion of proinflammatory cytokines, termed senescence-associated secretory phenotype. Chronic inflammation associated with aging has been called "inflammaging," and similar age-related diseases are becoming an urgent social problem.

CONCLUSION

In neuro ICUs, several neuro-related diseases including stroke and sepsis-associated encephalopathy are related to immunosenescence and neuroinflammation in the elderly. Several advanced countries with superaged societies face the new challenge of improving the long-term prognosis of neurocritical patients.

The efficacy and toxicity of immune checkpoint inhibitors in a real-world older patient population

IMPORTANCE

Immunotherapy has emerged as an effective treatment option for the management of advanced cancers. The effects of these immune checkpoint inhibitors in the older patient population has not been adequately assessed.

OBJECTIVE

To understand the impact of aging on CTLA-4 and PDL-1 inhibitors efficacy and immune-related adverse events (irAE) in the context of real-world management of advanced solid cancers.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective study involved all non-study patients with histologically-confirmed metastatic or inoperable solid cancers receiving immunotherapy at Kingston Health Sciences Centre. We defined 'older patient' as age ≥ 75. All statistical analyses were conducted under SPSS IBM for Windows version 24.0.

MAIN OUTCOMES AND MEASURES

Study outcomes included immunotherapy treatment response, survival, as well as number, type, and severity of irAEs.

RESULTS

Our study (N = 78) had 29 (37%) patients age <65, 26 (33%) patients age 65-74, and 23 (30%) patients age ≥75. Melanoma, non-small cell lung cancer, and renal cell carcinoma accounted for 70%, 22%, and 8% of the study population, respectively. Distributions of ipilimumab (32%), nivolumab (33%), and pembrolizumab (35%) were similar in the study. The response rates were 28%, 27%, and 39% in the age <65, age 64-74, age ≥75 groups, respectively (P = 0.585). Kaplan-Meier curve showed a median survival of 28 months (12.28-43.9, 95% CI) and 17 months (0-36.9, 95% CI) in the age <65 and age 64-74 groups, respectively; the estimated survival probability did not reach 50% in the age ≥75 group (P = 0.319). There were no statistically significant differences found in terms of irAEs, multiple irAEs, severity of grade 3 or higher, types of irAEs, and irAEs resolution status when comparing between different age groups.

CONCLUSION AND RELEVANCE

Our results suggest that patients age ≥75 are able to gain as much benefit from immunotherapy as younger patients, without excess toxicity. Our findings suggest that single agent immunotherapy is generally well-tolerated across different age groups with no significant difference in the type, frequency or severity of irAEs. Future studies evaluating aging and combination immunotherapy are warranted.

Elderly dendritic cells respond to LPS/IFN-γ and CD40L stimulation despite incomplete maturation

There is evidence that dendritic cells (DCs) undergo age-related changes that modulate their function with their key role being priming antigen-specific effector T cells. This occurs once DCs develop into antigen-presenting cells in response to stimuli/danger signals. However, the effects of aging on DC responses to bacterial lipopolysaccharide (LPS), the pro-inflammatory cytokine interferon (IFN)-γ and CD40 ligand (CD40L) have not yet been systematically evaluated. We examined responses of blood myeloid (m)DC1s, mDC2s, plasmacytoid (p)DCs, and monocyte-derived DCs (MoDCs) from young (21–40 years) and elderly (60–84 years) healthy human volunteers to LPS/IFN-γ or CD40L stimulation. All elderly DC subsets demonstrated comparable up-regulation of co-stimulatory molecules (CD40, CD80 and/or CD86), intracellular pro-inflammatory cytokine levels (IFN-γ, tumour necrosis factor (TNF)-α, IL-6 and/or IL-12), and/or secreted cytokine levels (IFN-α, IFN-γ, TNF-α, and IL-12) to their younger counterparts. Furthermore, elderly-derived LPS/IFN-γ or CD40L-activated MoDCs induced similar or increased levels of CD8⁺ and CD4⁺ T cell proliferation, and similar T cell functional phenotypes, to their younger counterparts. However, elderly LPS/IFN-γ-activated MoDCs were unreliable in their ability to up-regulate chemokine (IL-8 and monocyte chemoattractant protein (MCP)-1) and IL-6 secretion, implying an inability to dependably induce an inflammatory response. A key age-related difference was that, unlike young-derived MoDCs that completely lost their ability to process antigen, elderly-derived MoDCs maintained their antigen processing ability after LPS/IFN-γ maturation, measured using the DQ-ovalbumin assay; this response implies incomplete maturation that may enable elderly DCs to continuously present antigen. These differences may impact on the efficacy of anti-pathogen and anti-tumour immune responses in the elderly.

Cancer Immunotherapy in Older Patients

Advancing age remains one of the most significant risk factors for cancer development. Changes in the immune system occur with aging, and likely play a role in the increased incidence of malignancy in older patients. With the advent of immune checkpoint inhibitors, and their use in a variety of malignancies, there has been an explosion of clinical trials evaluating their use. Unfortunately, these trials have not shown consistent results in elderly patients, nor have age-specific outcomes been consistently reported. Further evaluation of the efficacy and toxicity of these agents in the elderly is needed, as they are now in frequent clinical use. By investigating how age-related changes in the immune system occur and intersect with use of immune checkpoint inhibitors, their use can be optimized in a clear and safe manner. Further study of age-related changes in the immune system can also lead to effective combination immunotherapeutic approaches, maximizing the efficacy of immune checkpoint inhibitors across tumor types and across the age spectrum of cancer patients.

Modulation of dendritic cell and T cell cross-talk during aging: The potential role of checkpoint inhibitory molecules

Dendritic cells (DCs) undergo continuous changes throughout life, and there is evidence that elderly DCs have a reduced capacity to stimulate T cells, which may contribute to impaired anti-tumour immune responses in elderly people with cancer. Changes in checkpoint inhibitory molecules/pathways during aging may be one mechanism that impairs the ability of elderly DCs to activate T cells. However, little is currently known regarding the combined effects of aging and cancer on DC and T cell inhibitory molecules/pathways. In this review, we discuss our current understanding of the influence of aging and cancer on key DC and T cell inhibitory molecules/pathways, the potential underlying cellular and molecular mechanisms contributing to their modulation, and the possibility of therapeutically targeting inhibitory molecules in elderly cancer patients.

The non-canonical Wnt pathway negatively regulates dendritic cell differentiation by inhibiting the expansion of Flt3(+) lymphocyte-primed multipotent precursors

The differentiation of dendritic cells (DC) is affected by the aging process. However, the molecular mechanisms responsible for the alteration of DC development in aged mice have not been clarified. Recently, Wnt5a was reported to be an important aging-related molecule in hematopoietic systems. Here, we hypothesized that the increased expression of Wnt5a in aged hematopoietic precursors led to deficient DC differentiation in aged mice. The percentages and cell numbers of plasmacytoid DC (pDC) and CD172a(-)CD8α(+)conventional DC (cDC) were decreased in aged mice compared to young mice. Further analysis indicated that the hematopoietic precursors that gave rise to DC, including Flt3(+) lymphoid-primed multipotent precursors (LMPP), common lymphoid progenitors (CLP) and common DC precursors (CDP), were all decreased in the bone marrow of aged mice. Overexpression of Wnt5a in hematopoietic precursors strongly affected the differentiation of cDC and pDC in vivo. Treatment of hematopoietic stem cells (HSC) with Wnt5a led to a significant decrease in the differentiation of the LMPP, CLP and CDP populations that was similar to the decrease observed in the bone marrow (BM) HSC of aged mice. Molecular studies demonstrated that Wnt5a negatively regulated the expression of an array of genes important for DC differentiation, including Flt3, Gfi-1, Ikaros, Bcl11a, and IL-7R, by activating the Wnt5a-Cdc42 pathway. Finally, we rejuvenated DC differentiation from aged precursors by blocking the non-canonical Wnt pathway. Our study identified the key roles of the non-canonical Wnt pathway in DC differentiation and DC aging.

Optimization of immunotherapy in elderly cancer patients

Increasing evidence has revealed the incidence of cancer augments with aging, which could be attributed to a multitude of age-associated changes including the dysregulation of the immune system. Although many reports demonstrate the efficacy of cancer immunotherapies in numerous preclinical studies, most experiments have been performed in young animals. Studies from our group and others show that cancer immunotherapy could be ineffective in old mice, even though the same therapeutic treatment works efficiently in young mice. Given that cancer occurs mostly in the elderly, we should take age-associated immune dysregulation into consideration to achieve the effectiveness of immunotherapeutic interventions in the old. Understanding both age-related and tumor-related immune alterations might be equally important in improving the effectiveness of immunotherapy. This article reviews a number of age-associated immune alterations with specific attention given to the impact on antitumor responses, and also discusses possible strategies for optimization of immunotherapeutic interventions in the elderly.

Mast cells and the liver aging process

It has now ascertained that the clinical manifestations of liver disease in the elderly population reflect both the cumulative effects of longevity on the liver and the generalized senescence of the organism ability to adjust to metabolic, infectious, and immunologic insults. Although liver tests are not significantly affected by age, the presentation of liver diseases such as viral hepatitis may be subtler in the elderly population than that of younger patients.

Human immunosenescence is a situation in which the immune system, particularly T lymphocyte function, deteriorates with age, while innate immunity is negligibly affected and in some cases almost up-regulated.

We here briefly review the relationships between the liver aging process and mast cells, the key effectors in a more complex range of innate immune responses than originally though.

Ageing impairs the T cell response to dendritic cells

Dendritic cells (DCs) are critical in priming adaptive T-cell responses, but the effects of ageing on interactions between DCs and T cells are unclear. This study investigated the influence of ageing on the maturation of and cytokine production by human blood-enriched DCs, and the impact on T cell responses in an allogeneic mixed leucocyte reaction (MLR). DCs from old subjects (65-75 y) produced significantly less TNF-α and IFN-γ than young subjects (20-30 y) in response to lipopolysaccharide (LPS), but expression of maturation markers and co-stimulatory molecules was preserved. In the MLR, DCs from older subjects induced significantly restricted proliferation of young T cells, activation of CD8+ T cells and expression of IL-12 and IFN-γ in T cells compared with young DCs. T cells from older subjects responded more weakly to DC stimulation compared with young T cells, regardless of whether the DCs were derived from young or older subjects. In conclusion, the capacity of DCs to induce T cell activation is significantly impaired by ageing.

Thymic function failure and C-reactive protein levels are independent predictors of all-cause mortality in healthy elderly humans

Relationship between thymic function and elderly survival has been suspected, despite the fact that formal proof is elusive due to technical limitations of thymic function-related markers. The newly described sj/β-TREC ratio allows now, by overcoming these limitations, an accurate measurement of thymic output in elderly humans. Thus, the aim of this study was to determine the impact of thymic function and inflammatory markers on healthy elderly human survival. Healthy volunteers (n = 151), aged over 65, were asked to participate (CARRERITAS cohort). Subjects were excluded if diagnosed of dementia or, during the last 6 months, had clinical data of infection, hospital admission, antitumor therapy, or any treatment that could influence the immune status. Thymic function (sj/β-TREC ratio), CD4:CD8 T cell ratio, C-reactive protein, interleukin-6, and neutrophilia were determined from basal samples. All basal variables and age were associated with 2-year all-cause mortality. Multivariate analysis showed that only thymic function and C-reactive protein were independently associated with time to death. In conclusion, we show, for the first time, the direct role of thymic function in human survival. C-reactive protein raise is also a marker of mortality in the healthy elderly, in a thymic-independent way.

Are aging biomarkers clinically relevant in oncogeriatrics?

Immunosenescence and inflammaging have been depicted for long as age-related heterogeneous blood phenotypic changes ("immunoaging"). Some of them can be reproduced in animal models either by accelerating telomere shortening or by forcing DNA damage response. According to these models, "immunoaging" is the consequence of replicative senescence of hematopoietic stem cells. This increasing knowledge may impact oncogeriatrics in the future since (1) an increasing evidence links hematopoietic and cancer stem cells regulations; (2) immunosenescence may be linked to cancer immunotolerance and the increasing rate of cancer incidence with age; (3) immunoaging has a major consequence during cancer treatment, since it explains increased hematological toxicities observed in the elderly and (4) it favors secondary cancers and mainly hemopathies. For all these reasons, aging biomarkers, among which are telomere length peripheral blood sampling but also analyses of telomere-linked proteins like shelterin complex or DNA-damage markers will probably be clinically relevant in the future.

Immunogenicity to biologics: mechanisms, prediction and reduction

Currently, there is a significant rise in the development and clinical use of a unique class of pharmaceuticals termed as Biopharmaceuticals or Biologics, in the management of a range of disease conditions with, remarkable therapeutic benefits. However, there is an equally growing concern regarding development of adverse effects like immunogenicity in the form of anti-drug antibodies (ADA) production and hypersensitivity. Immunogenicity to biologics represents a significant hurdle in the continuing therapy of patients in a number of disease settings. Efforts focussed on the identification of factors that contribute towards the onset of immunogenic response to biologics have led to reductions in the incidence of immunogenicity. An in-depth understanding of the cellular and molecular mechanism underpinning immunogenic responses will likely improve the safety profile of biologics. This review addresses the mechanistic basis of ADA generation to biologics, with emphasis on the role of antigen processing and presentation in this process. The article also addresses the potential contribution of complement system in augmenting or modulating this response. Identifying specific factors that influences processing and presentation of biologic-derived antigens in different genotype and disease background may offer additional options for intervention in the immunogenic process and consequently, the management of immunogenicity to biologics.

Characterization of MHC-II antigen presentation by B cells and monocytes from older individuals

In this study we examine the effects of aging on antigen presentation of B cells and monocytes. We compared the antigen presentation function of peripheral blood B cells from young and old subjects using a system that specifically measures the B cell receptor (BCR)-mediated MHC-II antigen presentation. Monocytes were studied as well. Overall the mean magnitude of antigen presentation of soluble antigen and peptide was not different in older and younger subjects for both B cells and monocytes. Older subjects, however, showed increased heterogeneity of BCR-mediated antigen presentation by their B cells. The magnitude and variability of peptide presentation, which do not require uptake and processing, were the same between groups. Presentation by monocytes had similar variability between the older and younger subjects. These data suggest that poor B cell antigen processing, which results in diminished presentation in some older individuals may contribute to poor vaccine responses.

Immunological treatment options for locoregionally advanced head and neck squamous cell carcinoma

Patients with squamous cell carcinoma of the head and neck (HNSCC) are usually treated by a multimodal approach with surgery and/or radiochemotherapy as the mainstay of local-regional treatment in cases with advanced disease. Both chemotherapy and radiation therapy have the disadvantage of causing severe side effects, while the clinical outcome of patients diagnosed with HNSCC has remained essentially unchanged over the last decade. The potential of immunotherapy is still largely unexplored. Here the authors review the current status of the art and discuss the future challenges in HNSCC treatment and prevention.

Age-related increases in PGD(2) expression impair respiratory DC migration, resulting in diminished T cell responses upon respiratory virus infection in mice

The morbidity and mortality associated with respiratory virus infection is felt most keenly among the elderly. T cells are necessary for viral clearance, and many age-dependent intrinsic T cell defects have been documented. However, the development of robust T cell responses in the lung also requires respiratory DCs (rDCs), which must process antigen and migrate to draining LNs (DLNs), and little is known about age-related defects in these T cell-extrinsic functions. Here, we show that increases in prostaglandin D(2) (PGD(2)) expression in mouse lungs upon aging correlate with a progressive impairment in rDC migration to DLNs. Decreased rDC migration resulted in diminished T cell responses and more severe clinical disease in older mice infected with respiratory viruses. Diminished rDC migration associated with virus-specific defects in T cell responses and was not a result of cell-intrinsic defect, rather it reflected the observed age-dependent increases in PGD(2) expression. Blocking PGD(2) function with small-molecule antagonists enhanced rDC migration, T cell responses, and survival. This effect correlated with upregulation on rDCs of CCR7, a chemokine receptor involved in DC chemotaxis. Our results suggest that inhibiting PGD(2) function may be a useful approach to enhance T cell responses against respiratory viruses in older humans.

Age-related Dysregulation of Inflammation and Innate Immunity: Lessons Learned from Rodent Models

In the elderly patient population, it has become increasingly evident that immune dysregulation is a contributing factor to age-related pathologies and their associated morbidity and mortality. In particular, elderly subjects are plagued by poor responses to infectious challenge and immunization and are at heightened risk for the development of autoimmune, neuroinflammatory and tumor-associated pathologies. Rodent models of aging and age-related disorders have been utilized to better describe how innate immune cell dysfunction contributes to these clinical scenarios. As the elderly population continues to increase in size, use of these aging rodent models to study immune dysregulation may translate into increased healthy living years for these individuals.

Systemic inflammation (Interleukin 6) predicts all-cause mortality in men: results from a 9-year follow-up of the MEMO Study

This study aimed to investigate the association of biomarkers among circulating pro-inflammatory cytokines with all-cause mortality in elderly community dwellings of the MEMO study, Germany. All-cause mortality (cancer, cardiovascular diseases (CVD), and other causes of death) was assessed in a general population sample (N = 385) of the elderly (age 65-83 years) 9 years after baseline assessment in 1998. As markers of inflammation, a variety of cytokines (IL-1beta, IL-4sR, IL-6, IL-8, IL-10, IL-12, TNF-alpha) were assessed in serum. Cox proportional Hazard model was used to estimate the association of cytokines with all-cause mortality over 9 years. In total, 110 deaths had occurred during follow-up (cancer N = 36; CVD N = 56; other = 18). Deaths were more frequent in male (N  = 76, 37.4%) as compared to females (N = 40, 21.9%; p  = 0.001). Among individual cytokines, IL-1 beta, IL-6, IL-8, IL-10, and TNF-alpha were associated with all-cause mortality, of which IL-6, IL-8, and IL-10 remained significant after adjusting for confounders. When the upper tertiles of these cytokines were compared to the lower tertiles, only IL-6 was consistently related to all-cause mortality independently of the level of adjustment and showing a dose-response relationship between IL-6 tertiles and risk of death. This effect originated in the male population. The study shows that IL-6 is a powerful predictor of all-cause mortality in male elderly community dwellings. Higher levels of IL-6 may reflect a chronic low-level systemic inflammation prospectively increasing the risk of death in the elderly.

Enhancement of virus-specific expansion of transgenic CD8 T cells in aged mice by dendritic cells

Aging is associated with a decreased CD8 T cell response to multiple antigens and to virus infection. Although both intrinsic and extrinsic factors have been shown to contribute to the decrease, the mechanisms are still largely unknown. In this study, the role of dendritic cells (DCs) in the age-associated decrease was examined. Influenza-specific TCR transgenic CD8 T cells of young mice demonstrated limited expansion in response to influenza infection when adoptively transferred to aged compared to young mice. This decreased response in aged mice could be significantly enhanced when DCs of young mice were co-transferred. Co-transfer of DCs had no impact in young recipient mice. Adoptive transfer of the DCs also increased the endogenous CD8 T cell response of intact aged mice, although to a lesser degree. These results suggest that the diminished CD8 T cell response to virus infection in aged mice is partially attributable to age-associated changes in DCs.

Rheumatoid arthritis: a role for immunosenescence?

Aging is accompanied by a progressive decline in the integrity of the immune system, a process known as immunosenescence. Pathological features typical of immune dysfunction in older adults, encompassing dysregulation of innate and adaptive immune responses, characterize rheumatoid arthritis (RA), an autoimmune disease whose incidence increases with age. Recent evidence suggests that certain features of immunosenescence, such as the decrease in T-cell generation and diversity, may contribute to the development of RA. Thus, physiological immunosenescence may render older adults susceptible to RA, and premature immunosenescence may contribute to the development of RA in young adults. In addition, other features of immunosenescence may result from the chronic immune stimulation that occurs in RA and lead to worsening of the disease. This article reviews the immunopathological features common to aging and RA and discusses the mechanisms by which immunosenescence may contribute to the development or progression of RA.

Limited expansion of virus-specific CD8 T cells in the aged environment

The mechanisms responsible for the diminished immune response seen with aging are unclear. In this study, we investigate the contributions of alterations in the lymphoid microenvironment to this decrease. Using adoptive transfer of virus-specific transgenic CD8 T cells, we demonstrate that the aged environment inhibits the clonal expansion of specific CD8 T cells from young mice during virus infection. Transferred specific CD8 T cells from young mice demonstrated a response reflecting the CD8 T cell response of the intact aged host: the CD8 T cells expand more slowly and have a decreased maximal expansion in an aged compared to a young environment. While isolated DCs (MHC II(+) CD11c(+)) of aged mice maintain their ability to support CD8 T cell Ag-specific expansion in vitro, splenocytes demonstrated an age-associated decrease in this ability. Since the percentages of various populations of DCs in splenocytes demonstrate no significant alteration with age, this diminished APC activity of splenocytes of aged mice may reflect inhibitory activity of other cell populations. The results of this study demonstrate that elements of the aged environment play an important role in the alteration of T cell response to virus infection in the aged.

Leukocyte function in the aging immune system

Aging is associated with a progressive dysregulation of immune responses. Whether these changes are solely responsible for the observed increased mortality and morbidity amongst the elderly is uncertain. Recent advances have highlighted the age-associated changes that occur beyond T and B lymphocytes. Additionally, multiple human and animal studies have identified a relationship between chronic low-grade inflammation and geriatric syndromes, such as frailty, suggesting that the phenomenon of "inflamm-aging" may provide a rationale for the increased vulnerability to chronic inflammatory diseases in older adults. In the present review, we broadly summarize our current understanding of age-dependent changes in leukocyte function and their contribution to aging-related disease processes.

Effect of aging and oral tolerance on dendritic cell function

Oral tolerance can be induced in some mouse strains by gavage or spontaneous ingestion of dietary antigens. In the present study, we determined the influence of aging and oral tolerance on the secretion of co-stimulatory molecules by dendritic cells (DC), and on the ability of DC to induce proliferation and cytokine secretion by naive T cells from BALB/c and OVA transgenic (DO11.10) mice. We observed that oral tolerance could be induced in BALB/c mice (N = 5 in each group) of all ages (8, 20, 40, 60, and 80 weeks old), although a decline in specific antibody levels was observed in the sera of both tolerized and immunized mice with advancing age (40 to 80 weeks old). DC obtained from young, adult and middle-aged (8, 20, and 40 weeks old) tolerized mice were less efficient (65, 17 and 20%, respectively) than DC from immunized mice (P < 0.05) in inducing antigen-specific proliferation of naive T cells from both BALB/c and DO11.10 young mice, or in stimulating IFN-g, IL-4 and IL-10 production. However, TGF-beta levels were significantly elevated in co-cultures carried out with DC from tolerant mice (P < 0.05). DC from both immunized and tolerized old and very old (60 and 80 weeks old) mice were equally ineffective in inducing T cell proliferation and cytokine production (P < 0.05). A marked reduction in CD86+ marker expression was observed in DC isolated from both old and tolerized mice (75 and 50%, respectively). The results indicate that the aging process does not interfere with the establishment of oral tolerance in BALB/c mice, but reduces DC functions, probably due to the decline of the expression of the CD86 surface marker.

Aging and innate immunity in the mouse: impact of intrinsic and extrinsic factors

Aging affects every innate immune cell, including changes in cell numbers and function. Defects in the function of some cells are intrinsic, whereas for other cells, defects are extrinsic and possibly the consequence of the complex interactions with other cell types or the environmental milieu that is altered with aging. Abnormal function contributes to worsened outcomes after injury or infection and leads to diseases observed in the elderly. Knowing the mechanisms responsible for the aberrant function of innate immune cells might lead to the development of therapeutic strategies designed to improve innate immunity in aged individuals. Herein, advances in the field of innate immunity and aging with a focus on neutrophils, macrophages and dendritic cells in laboratory animals are discussed.

Cellular senescence, ageing and disease

Cellular senescence is the irreversible growth arrest of individual mitotic cells, which as a consequence display a radically altered phenotype that is thought to impair tissue function and predispose tissues to disease development and/or progression as they gradually accumulate. However, in the past, research into mechanisms of ageing has commonly been researched and treated separately from disease development. This may partly be due to the lack of understanding concerning mechanisms of ageing and the difficulty in implementing what was known into models of disease development. Only in the last 10 years, with increasing knowledge of the senescent phenotype and the ability to detect senescent cells in human tissues, have biologists been able to investigate the relationship between cellular senescence and disease. This review therefore brings together and discusses recent findings which suggest that cellular senescence does contribute to ageing and the development/progression of disease.

Mechanisms of murine dendritic cell antitumor dysfunction in aging

Effective cancer immunotherapy depends on the body's ability to generate tumor antigen-presenting cells and tumor-reactive effector lymphocytes. As the most potent antigen presenting cells (APCs), dendritic cells (DCs) are capable of sensitizing T cells to new and recall antigens. Clinical trials of antigen-pulsed autologous DCs have been conducted in patients with a number of hematological and solid cancers, including malignant melanoma, lymphoma, myeloma, and non-small cell lung cancer. These studies suggest that antigen-loaded DC vaccination is a potentially safe and effective cancer therapy. However, the clinical results have been variable. Since the elderly are preferentially affected by diseases targeted by DC-directed immunotherapy, it is quite striking that few studies to date have focused on the effect of aging on DC function, a key aspect of optimal immunotherapy design in an aging population. In the present paper, we will discuss the consequences of aging on murine bone marrow-derived DC function and their use in cancer immunotherapy.

Impaired dendritic cell function in aging leads to defective antitumor immunity

We recently reported that bone marrow-derived dendritic cells (DC) from aged miced are less effective than their young counterparts in inducing the regression of B16-ovalbumin (OVA) melanomas. To examine the underlying mechanisms, we investigated the effect of aging on DC tumor antigen presentation and migration. Although aging does not affect the ability of DCs to present OVA peptide((257-264)), DCs from aged mice are less efficient than those from young mice in stimulating OVA-specific T cells in vitro. Phenotypic analysis revealed a selective decrease in DC-specific/intracellular adhesion molecule type-3-grabbing nonintegrin (DC-SIGN) level in aged DCs. Adoptive transfer experiments showed defective in vivo DC trafficking in aging. This correlates with impaired in vitro migration and defective CCR7 signaling in response to CCL21 in aged DCs. Interestingly, vaccination of young mice using old OVA peptide((257-264))-pulsed DCs (OVA PP-DC) resulted in impaired activation of OVA-specific CD8(+) T cells in vivo. Effector functions of these T cells, as determined by IFN-gamma production and cytotoxic activity, were similar to those obtained from mice vaccinated with young OVA PP-DCs. A decreased influx of intratumor CD8(+) T cells was also observed. Importantly, although defective in vivo migration could be restored by increasing the number of old DCs injected, the aging defect in DC tumor surveillance and OVA-specific CD8(+) T-cell induction remained. Taken together, our findings suggest that defective T-cell stimulation contributes to the observed impaired DC tumor immunotherapeutic response in aging.

Inflammatory response gene polymorphisms and their relationship with colorectal cancer risk

Backgroud

Patients with chronic inflammatory bowel disease (IBD) are at an increased risk of colorectal cancer (CRC) and it is estimated that one in six persons diagnosed with IBD will develop CRC. This fact suggests that genetic variations in inflammatory response genes may act as CRC disease risk modifiers.

Methods

In order to test this hypothesis we investigated a series of polymorphisms in 6 genes (NOD2, DLG5, OCTN1, OCTN2, IL4, TNFα) associated with the inflammatory response on a group of 607 consecutive newly diagnosed colorectal cancer patients and compared the results to controls (350 consecutive newborns and 607 age, sex and geographically matched controls).

Results

Of the six genes only one polymorphism in TNFα(-1031T/T) showed any tendency to be associated with disease risk (64.9% for controls and 71.4% for CRC) which we further characterized on a larger cohort of CRC patients and found a more profound relationship between the TNFα -1031T/T genotype and disease (64.5% for controls vs 74.7% for CRC cases above 70 yrs). Then, we investigated this result and identified a suggestive tendency, linking the TNFα -1031T/T genotype and a previously identified change in the CARD15/NOD2 gene (OR = 1.87; p = 0,02 for CRC cases above 60 yrs).

Conclusion

The association of polymorphisms in genes involved in the inflammatory response and CRC onset suggest that there are genetic changes capable of influencing disease risk in older persons.

Nrf2 activation by sulforaphane restores the age-related decrease of T(H)1 immunity: role of dendritic cells

BACKGROUND

The decrease in cellular immunity with aging is of considerable public health importance. Recent studies suggest that the redox equilibrium of dendritic cells (DCs) is a key factor in maintaining protective cellular immunity and that a disturbance of this homeostatic mechanism could contribute to immune senescence.

OBJECTIVES

We sought (1) to elucidate the role of DC redox equilibrium in the decrease of contact hypersensitivity (CHS) and T(H)1 immunity during aging and (2) to determine how restoration of glutathione (GSH) levels by the Nrf2-mediated antioxidant defense pathway affects this decrease.

METHODS

We assessed the effect of Nrf2 deficiency and boosting of GSH levels by the Nrf2 agonist sulforaphane or the thiol precursor N-acetyl cysteine (NAC) on the CHS response to contact antigens in old mice. We studied the effect of SFN and NAC on restoring T(H)1 immunity by treating DCs ex vivo before adoptive transfer and in vivo challenge.

RESULTS

Aging was associated with a decreased CHS response that was accentuated by Nrf2 deficiency. Systemic SFN treatment reversed this decrease through Nrf2-mediated antioxidant enzyme expression and GSH synthesis. Adoptive transfer of DCs from old animals induced a weakened CHS response in recipient animals. Treatment of DCs from old animals with SFN or NAC ex vivo restored the in vivo challenge response.

CONCLUSION

SFN and NAC upregulate T(H)1 immunity in aging through a restoration of redox equilibrium.