CD4+T cells play a notable role in immune protection at different stages of life. During aging, the interaction between the body\'s internal and external environment and CD4+T cells results in a series of changes in the CD4+T cells pool making it involved in immunosenescence. Many studies have extensively examined the subsets and functionality of CD4+T cells within the immune system, highlighted their pivotal role in disease pathogenesis, progression, and therapeutic interventions. However, the underlying mechanism of CD4+T cells senescence and its intricate association with diseases remains to be elucidated and comprehensively understood. By summarizing the immunosenescent progress and network of CD4+T cell subsets, we reveal the crucial role of CD4+T cells in the occurrence and development of age-related diseases. Furthermore, we provide new insights and theoretical foundations for diseases targeting CD4+T cell subsets aging as a treatment focus, offering novel approaches for therapy, especially in infections, cancers, autoimmune diseases, and other diseases in the elderly.

The number of older adults worldwide is growing exponentially. However, while living longer, older individuals are more susceptible to both non-infectious and infectious diseases, at least in part due to alterations of the immune system. Here, we report on a prospective cohort study investigating the influence of age on immune responses and susceptibility to infection. The RESIST Senior Individuals (SI) cohort was established as a general population cohort with a focus on the elderly, enrolling an age- and sex-stratified sample of 650 individuals (n = 100 20-39y, n = 550 61-94y, 2019-2023, Hannover, Germany). It includes clinical, demographic, and lifestyle data and also extensive biomaterial sampling. Initial insights indicate that the SI cohort exhibits characteristics of the aging immune system and the associated susceptibility to infection, thereby providing a suitable platform for the decoding of age-related alterations of the immune system and unraveling the molecular mechanisms underlying the impaired immune responsiveness in aging populations by exploring comprehensive, unbiased multi-omics datasets.

The immune system is a major regulatory system of the body, that is composed of immune cells, immune organs, and related signaling factors. As an organism ages, observable age-related changes in the function of the immune system accumulate in a process described as \'immune aging. Research has shown that the impact of aging on immunity is detrimental, with various dysregulated responses that affect the function of immune cells at the cellular level. For example, increased aging has been shown to result in the abnormal chemotaxis of neutrophils and decreased phagocytosis of macrophages. Age-related diminished functionality of immune cell types has direct effects on host fitness, leading to poorer responses to vaccination, more inflammation and tissue damage, as well as autoimmune disorders and the inability to control infections. Similarly, age impacts the function of the immune system at the organ level, resulting in decreased hematopoietic function in the bone marrow, a gradual deficiency of catalase in the thymus, and thymic atrophy, resulting in reduced production of related immune cells such as B cells and T cells, further increasing the risk of autoimmune disorders in the elderly. As the immune function of the body weakens, aging cells and inflammatory factors cannot be cleared, resulting in a cycle of increased inflammation that accumulates over time. Cumulatively, the consequences of immune aging increase the likelihood of developing age-related diseases, such as Alzheimer\'s disease, atherosclerosis, and osteoporosis, among others. Therefore, targeting the age-related changes that occur within cells of the immune system might be an effective anti-aging strategy. In this article, we summarize the relevant literature on immune aging research, focusing on its impact on aging, in hopes of providing new directions for anti-aging research.

Cancer is generally defined as a disease of aging. With aging, the composition, diversity and functional characteristics of the gut microbiota occur changes, with a decline of beneficial commensal microbes triggered by intrinsic and extrinsic factors (e.g., diet, drugs and chronic health conditions). Nowadays, dysbiosis of the gut microbiota is recognized as a hallmark of cancer. At the same time, aging is accompanied by changes in innate and adaptive immunity, known as immunosenescence, as well as chronic low-grade inflammation, known as inflammaging. The elevated cancer incidence and mortality in the elderly are linked with aging-associated alterations in the gut microbiota that elicit systemic metabolic alterations, leading to immune dysregulation with potentially tumorigenic effects. The gut microbiota and immunosenescence might both affect the response to treatment in cancer patients. In-depth understanding of age-associated alterations in the gut microbiota and immunity will shed light on the risk of cancer development and progression in the elderly. Here, we describe the aging-associated changes of the gut microbiota in cancer, and review the evolving understanding of the gut microbiota-targeted intervention strategies. Furthermore, we summarize the knowledge on the cellular and molecular mechanisms of immunosenescence and its impact on cancer. Finally, we discuss the latest knowledge about the relationships between gut microbiota and immunosenescence, with implications for cancer therapy. Intervention strategies targeting the gut microbiota may attenuate inflammaging and rejuvenate immune function to provide antitumor benefits in elderly patients.

The aim of this study was to assess the relationship of different chronic diseases with immunonutritional markers in the senior population.
METHODS: this study included 1190 hospitalized geriatric patients. The criteria to participate were ability to communicate, given consent and C-reactive protein (CRP) lower than 6 mg/dL.
RESULTS: the mean age of the study population was 81.7 ± 7.6 years. NLR (neutrophil-to-lymphocyte ratio), LMR (lymphocyte-to-monocyte ratio), MWR (monocyte-to-white blood cell ratio), SII (systemic immune-inflammation index), PNI (prognostic nutritional index) and CAR (C-reactive protein-to-albumin ratio) were related to age. NLR and MWR were higher, while LMR, PLR (platelet-to-lymphocyte ratio and SII were lower in men. All markers were related to BMI. NLR, LMR, LCR (lymphocyte-to-CRP ratio), MWR, PNI and CAR were related to several concomitant chronic diseases. In multivariate analyses, age and BMI were selected as independent predictors of all studied immunonutritional markers. Atrial fibrillation, diabetes mellitus and dementia appear most often in the models. PNI presented the most consistent statistical association with age, BMI and concomitant chronic diseases.
CONCLUSIONS: this study reveals the pivotal role of aging and BMI in inflammatory marker levels and the association of immunonutritional markers with different chronic diseases. Atrial fibrillation seems to have the most dominant connection to the immunonutritional markers.

BACKGROUND: During the COVID19 pandemic, older patients hospitalized for COVID-19 exhibited an increased mortality risk compared to younger patients. While ageing is associated with compromised immune responses and frailty, their contributions and interplay remain understudied. This study investigated the association between inflammatory markers and mortality and potential modification by frailty among older patients hospitalized for COVID-19.
METHODS: Data were from three multicenter Dutch cohorts (COVID-OLD, CliniCo, Covid-Predict). Patients were 70 years or older, hospitalized for COVID-19and categorized into three frailty groups: fit (Clinical frailty score (CFS) 1-3), pre-frail (CFS 4-5), and frail (CFS 6-9). Immunological markers (lymphocyte count, neutrophil count, C-reactive protein, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic inflammation index (SII)) were measured at baseline. Associations with in hospital mortality were examined using logistic regression.
RESULTS: A total of 1697 patients were included from COVID-OLD, 656 from Covid-Predict, and 574 from CliniCo. The median age was 79, 77, and 78 years for each cohort. Hospital mortality rates were 33 %, 27 % and 39 % in the three cohorts, respectively. A lower CRP was associated with a higher frailty score in all three cohorts (all p < 0.01). Lymphocyte count, neutrophil count, NLR, PLR, or SII, were similar across frailty groups. Higher CRP levels were associated with increased in-hospital mortality risk across all frailty groups, across all cohorts (OR (95 % CI), 2.88 (2.20-3.78), 3.15 (1.95-5.16), and 3.28 (1.87-5.92)), and frailty did not modify the association between inflammatory markers and in-hospital mortality (all p-interaction>0.05).
CONCLUSIONS: While frailty is a significant factor in determining overall outcomes in older patients, our study suggests that the elevated risk of mortality in older patients with frailty compared to fit patients is likely not explained by difference in inflammatory responses.

Almost all currently licensed disease-modifying therapies (DMTs) for MS treatment require prolonged if not lifelong administration. Yet, as people age, the immune system has increasingly reduced responsiveness, known as immunosenescence. Many MS DMTs reduce the responsiveness of the immune system, increasing the risks for infections and possibly cancers. As people with MS (pwMS) age, it is recognized that inflammatory MS activity declines. Several studies have addressed de-escalation of DMTs for relapsing MS under special circumstances. Here, we review evidence for de-escalating DMTs as a strategy that is particularly relevant to pwMS of older age. Treatment de-escalation can involve various strategies, such as extended or reduced dosing, switching from high-efficacy DMTs having higher risks to moderately effective DMTs with lesser risks, or treatment discontinuation. Studies have suggested that for natalizumab extended dosing maintained clinical efficacy while reducing the risk of PML. Extended interval dosing of ocrelizumab mitigated the decline of Ig levels. Retrospective and observational discontinuation studies demonstrate that age is an essential modifier of drug efficacy. Discontinuation of MS treatment in older patients has been associated with a stable disease course, while younger patients who discontinued treatment were more likely to experience new clinical activity. A recently completed 2-year randomized-controlled discontinuation study in 260 stable pwMS > 55 years found stable clinical multiple sclerosis with only a small increased risk of new MRI activity upon discontinuation. DMT de-escalation or discontinuation in MS patients older than 55 years may be non-inferior to continued treatment with immunosuppressive agents having higher health risks. However, despite several small studies, a definite conclusion about treatment de-escalation in older pwMS will require larger and longer studies. Ideally, comparison of de-escalation versus continuation versus discontinuation of DMTs should be done by prospective randomized-controlled trials enrolling sufficient numbers of subjects to allow comparisons for MS patients of both sexes within age groups, such as 55-59, 60-65, 66-69, etc. Optimally, such studies should be 3 years or longer and should incorporate testing for specific markers of immunosenescence (such as T-cell receptor excision circles) to account for differential aging of individuals.

Fibrosing interstitial lung diseases (ILDs) are characterized by the gradual and irreversible accumulation of scar tissue in the lung parenchyma. The role of the immune response in the pathogenesis of pulmonary fibrosis remains unclear. In recent years, substantial advancements have been made in our comprehension of the pathobiology driving fibrosing ILDs, particularly concerning various age-related cellular disturbances and immune mechanisms believed to contribute to an inadequate response to stress and increased susceptibility to lung fibrosis. Emerging studies emphasize cellular senescence as a key mechanism implicated in the pathobiology of age-related diseases, including pulmonary fibrosis. Cellular senescence, marked by antagonistic pleiotropy, and the complex interplay with immunity, are pivotal in comprehending many aspects of lung fibrosis. Here, we review progress in novel concepts in cellular senescence, its association with the dysregulation of the immune response, and the evidence underlining its detrimental role in fibrosing ILDs.

Immunosenescence poses a significant challenge to tumor immunotherapy in elderly individuals. In this issue of Cell, Zhivaki et al. elucidate that dendritic cells \"hyperactivated\" by specific adjuvants elicit TH1-skewed CD4+ T cell responses in a manner contingent on the NLRP3 inflammasome, which can eliminate tumors in aged mice.

It has been believed that immunosenescence plays a crucial role in tumorigenesis and cancer therapy. Nevertheless, there is still a lack of understanding regarding its role in determining clinical outcomes and therapy selection for gastric cancer patients, due to the lack of a feasible immunosenescence signature. Therefore, this research aims to develop a gene signature based on immunosenescence, which is used for stratification of gastric cancer. By integrative analysis of bulk transcriptome and single-cell data, we uncovered immunosenescence features in gastric cancer. Random forest algorithm was used to select hub genes and multivariate Cox algorithm was applied to construct a scoring system to evaluate the prognosis and the response to immunotherapy and chemotherapy. The Cancer Genome Atlas of Stomach Adenocarcinoma (TCGA-STAD) cohort was implemented as the training cohort and two independent cohorts from the Gene Expression Omnibus (GEO) database were used for validation. The model was further tested by our Fudan cohort. In this study, immunosenescence was identified as a hallmark of gastric cancer that is linked with transcriptomic features, genomic variations, and distinctive tumor microenvironment (TME). Four immunosenescence genes, including APOD, ADIPOR2, BRAF, and C3, were screened out to construct a gene signature for risk stratification. Higher risk scores indicated strong predictive power for poorer overall survival. Notably, the risk score signature could reliably predict response to chemotherapy and immunotherapy, with patients with high scores benefiting from immunotherapy and patients with low scores responding to chemotherapy. We report immunosenescence as a hitherto unheralded hallmark of gastric cancer that affects prognosis and treatment efficiency.