From inflamm-aging to immune-paralysis: a slippery slope during aging for immune-adaptation

Deciphering the role of cytokines in aging: Biomarker potential and effective targeting

Aging is often characterized by chronic inflammation, immune system dysregulation, and cellular senescence with chronically elevated levels of pro-inflammatory cytokines. These small glycoproteins are mainly secreted by immune cells, mediating intercellular communication and immune system modulation through inflammatory signaling. Their pro- and anti-inflammatory effects make them a noteworthy research topic as well as a promising ally in combating inflammation and the aging process. Cytokines exert a synergistic role in aging and disease and may prove useful biomarkers of tissue-specific dysregulation, disease diagnosis and monitoring, presenting potential therapeutic options as anti-inflammatory and senolytic medications. In this review, we address the cellular and molecular mechanisms implicating cytokines in the aging process and related diseases, highlighting their biomarker potential. We focus on the current therapeutic strategies, including specific pharmaceutical agents, supplements, a balanced diet, and healthy habits such as exercise, stress management, and caloric restriction.

Impact of immunological aging on T cell-mediated therapies in older adults with multiple myeloma and lymphoma

The treatment landscape for lymphoma and multiple myeloma, which disproportionally affect older adults, has been transformed by the advent of T cell-mediated immunotherapies, including immune checkpoint inhibition, T cell-engaging bispecific antibodies, and chimeric antigen receptor (CAR) T cell therapy, during the last decade. These treatment modalities re-enable the patient's own immune system to combat malignant cells and offer the potential for sustained remissions and cure for various diseases.Age profoundly affects the physiological function of the immune system. The process of biological aging is largely driven by inflammatory signaling, which is reciprocally fueled by aging-related alterations of physiology and metabolism. In the T cell compartment, aging contributes to T cell senescence and exhaustion, increased abundance of terminally differentiated cells, a corresponding attrition in naïve T cell numbers, and a decrease in the breadth of the receptor repertoire. Furthermore, inflammatory signaling drives aging-related pathologies and contributes to frailty in older individuals. Thus, there is growing evidence of biological aging modulating the efficacy and toxicity of T cell-mediated immunotherapies.Here, we review the available evidence from biological and clinical studies focusing on the relationship between T cell-mediated treatment of hematologic malignancies and age. We discuss biological features potentially impacting clinical outcomes in various scenarios, and potential strategies to improve the safety and efficacy of immune checkpoint inhibitors, T cell-engaging bispecific antibodies, and CAR-T cell therapy in older patients.

The emerging links between immunosenescence in innate immune system and neurocryptococcosis

Immunosenescence refers to the age-related progressive decline of immune function contributing to the increased susceptibility to infectious diseases in older people. Neurocryptococcosis, an infectious disease of central nervous system (CNS) caused by Cryptococcus neoformans (C. Neoformans) and C. gattii, has been observed with increased frequency in aged people, as result of the reactivation of a latent infection or community acquisition. These opportunistic microorganisms belonging to kingdom of fungi are capable of surviving and replicating within macrophages. Typically, cryptococcus is expelled by vomocytosis, a non-lytic expulsive mechanism also promoted by interferon (IFN)-I, or by cell lysis. However, whereas in a first phase cryptococcal vomocytosis leads to a latent asymptomatic infection confined to the lung, an enhancement in vomocytosis, promoted by IFN-I overproduction, can be deleterious, leading the fungus to reach the blood stream and invade the CNS. Cryptococcus may not be easy to diagnose in older individuals and, if not timely treated, could be potentially lethal. Therefore, this review aims to elucidate the putative causes of the increased incidence of cryptococcal CNS infection in older people discussing in depth the mechanisms of immunosenscence potentially able to predispose to neurocryptococcosis, laying the foundations for future research. A deepest understanding of this relationship could provide new ways to improve the prevention and recognition of neurocryptococcosis in aged frail people, in order to quickly manage pharmacological interventions and to adopt further preventive measures able to reduce the main risk factors.

Enhancing Immune Responses against SARS-CoV-2 Variants in Aged Mice with INDUK: A Chimeric DNA Vaccine Encoding the Spike S1-TM Subunits

Currently available vaccines against COVID-19 showed high efficacy against the original strain of SARS-CoV-2 but progressively lower efficacy against new variants. In response to emerging SARS-CoV-2 strains, we propose chimeric DNA vaccines encoding the spike antigen, including a combination of selected key mutations from different variants of concern. We developed two DNA vaccines, pVAX-S1-TM-D614G and pVAX-S1-TM-INDUK (INDUK), encoding the SARS-CoV-2 S1 spike subunit in fusion with the transmembrane region that allows protein trimerization as predicted by in silico analysis. pVAX-S1-TM-D614G included the dominant D614G substitution, while the chimeric vaccine INDUK contained additional selected mutations from the Delta (E484Q and L452R) and Alpha (N501Y and A570D) variants. Considering that aging is a risk factor for severe disease and that suboptimal vaccine responses were observed in older individuals, the immunogenicity of pVAX-S1-TM-D614G and INDUK was tested in both young and aged C57BL/6 mice. Two vaccine doses were able to trigger significant anti-SARS-CoV-2 antibody production, showing neutralizing activity. ELISA tests confirmed that antibodies induced by pVAX-S1-TM-D614G and INDUK were able to recognize both Wuhan Spike and Delta variant Spike as trimers, while neutralizing antibodies were detected by an ACE2:SARS-CoV-2 Spike S1 inhibitor screening assay, designed to assess the capacity of antibodies to block the interaction between the viral spike S1 protein and the ACE2 receptor. Although antibody titer declined within six months, a third booster dose significantly increased the magnitude of humoral response, even in aged individuals, suggesting that immune recall can improve antibody response durability. The analysis of cellular responses demonstrated that vaccination with INDUK elicited an increase in the percentage of SARS-CoV-2-specific IFN-γ producing T lymphocytes in immunized young mice and TNF-α-producing T lymphocytes in both young and aged mice. These findings not only hold immediate promise for addressing evolving challenges in SARS-CoV-2 vaccination but also open avenues to refine strategies and elevate the effectiveness of next-generation vaccines.

Ganoderma lucidum dry extract supplementation modulates T lymphocyte function in older women

Ganoderma lucidum (a mushroom used in traditional Chinese medicine) compounds may attenuate ageing-related physiological changes and restore normal immunity. However, studies on the physiological effects of Ganoderma lucidum dry extract food supplements are few. Therefore, here, we aimed to investigate the effects of Ganoderma lucidum dry extract food supplement on the lymphocyte function of older women. This was a double-blind clinical trial (n 60) with a final 39 older volunteers, divided into two groups Ganoderma lucidum (n 23) and placebo (n 16). The Ganoderma lucidum group received 2000 mg/d of Ganoderma lucidum dry extract for 8 weeks. We used flow cytometry to determine the lymphocyte profile. CD4+ lymphocyte gene expression was evaluated by real-time polymerase chain reaction. We observed that in the Ganoderma lucidum group, concanavalin A stimulation increased lymphocyte proliferation. Further, we observed an increase in expression of Forkhead box P3, transforming growth factor-beta, IL-10, IL-6, retinoic acid receptor-related orphan receptor gamma, GATA-binding protein 3 and interferon gamma genes in the Ganoderma lucidum group. Furthermore, in the Ganoderma lucidum group, ionomycin and phorbol 12-myristate 13-acetate stimulation led to decrease in Th17+ cells and increase in Th2+ cells. Thus, in older women, Ganoderma lucidum regulates T lymphocyte function leading to a predominant anti-inflammatory action but does not induce T lymphocyte proliferation through CD28 signalling pathway.

SuperAgers and centenarians, dynamics of healthy ageing with cognitive resilience

Graceful healthy ageing and extended longevity is the most desired goal for human race. The process of ageing is inevitable and has a profound impact on the gradual deterioration of our physiology and health since it triggers the onset of many chronic conditions like dementia, osteoporosis, diabetes, arthritis, cancer, and cardiovascular disease. However, some people who lived/live more than 100 years called 'Centenarians" and how do they achieve their extended lifespans are not completely understood. Studying these unknown factors of longevity is important not only to establish a longer human lifespan but also to manage and treat people with shortened lifespans suffering from age-related morbidities. Furthermore, older adults who maintain strong cognitive function are referred to as "SuperAgers" and may be resistant to risk factors linked to cognitive decline. Investigating the mechanisms underlying their cognitive resilience may contribute to the development of therapeutic strategies that support the preservation of cognitive function as people age. The key to a long, physically, and cognitively healthy life has been a mystery to scientists for ages. Developments in the medical sciences helps us to a better understanding of human physiological function and greater access to medical care has led us to an increase in life expectancy. Moreover, inheriting favorable genetic traits and adopting a healthy lifestyle play pivotal roles in promoting longer and healthier lives. Engaging in regular physical activity, maintaining a balanced diet, and avoiding harmful habits such as smoking contribute to overall well-being. The synergy between positive lifestyle choices, access to education, socio-economic factors, environmental determinants and genetic supremacy enhances the potential for a longer and healthier life. Our article aims to examine the factors associated with healthy ageing, particularly focusing on cognitive health in centenarians. We will also be discussing different aspects of ageing including genomic instability, metabolic burden, oxidative stress and inflammation, mitochondrial dysfunction, cellular senescence, immunosenescence, and sarcopenia.

Genomic signatures of exceptional longevity and negligible aging in the long-lived red sea urchin

The red sea urchin (Mesocentrotus franciscanus) is one of the Earth's longest-living animals, reported to live more than 100 years with indeterminate growth, life-long reproduction, and no increase in mortality rate with age. To understand the genetic underpinnings of longevity and negligible aging, we constructed a chromosome-level assembly of the red sea urchin genome and compared it to that of short-lived sea urchin species. Genome-wide syntenic alignments identified chromosome rearrangements that distinguish short- and long-lived species. Expanded gene families in long-lived species play a role in innate immunity, sensory nervous system, and genome stability. An integrated network of genes under positive selection in the red sea urchin was involved in genomic regulation, mRNA fidelity, protein homeostasis, and mitochondrial function. Our results implicated known longevity genes in sea urchin longevity but also revealed distinct molecular signatures that may promote long-term maintenance of tissue homeostasis, disease resistance, and negligible aging.

Understanding the intricacies of cellular senescence in atherosclerosis: Mechanisms and therapeutic implications

Cardiovascular disease is currently the largest cause of mortality and disability globally, surpassing communicable diseases, and atherosclerosis is the main contributor to this epidemic. Aging is intimately linked to atherosclerosis development and progression, however, the mechanism of aging in atherosclerosis is not well known. To emphasize the significant research on the involvement of senescent cells in atherosclerosis, we begin by outlining compelling evidence that indicates various types of senescent cells and SASP factors linked to atherosclerotic phenotypes. We subsequently provide a comprehensive summary of the existing knowledge, shedding light on the intricate mechanisms through which cellular senescence contributes to the pathogenesis of atherosclerosis. Further, we cover that senescence can be identified by both structural changes and several senescence-associated biomarkers. Finally, we discuss that preventing accelerated cellular senescence represents an important therapeutic potential, as permanent changes may occur in advanced atherosclerosis. Together, the review summarizes the relationship between cellular senescence and atherosclerosis, and inspects the molecular knowledge, and potential clinical significance of senescent cells in developing senescent-based therapy, thus providing crucial insights into their biology and potential therapeutic exploration.

The molecular mechanism of aging and the role in neurodegenerative diseases

Aging is a complex and inevitable biological process affected by a combination of external environmental and genetic factors. Humans are currently living longer than ever before, accompanied with aging-related alterations such as diminished autophagy, decreased immunological function, mitochondrial malfunction, stem cell failure, accumulation of somatic and mitochondrial DNA mutations, loss of telomere, and altered nutrient metabolism. Aging leads to a decline in body functions and age-related diseases, for example, Alzheimer's disease, which adversely affects human health and longevity. The quality of life of the elderly is greatly diminished by the increase in their life expectancy rather than healthy life expectancy. With the rise in the age of the global population, aging and related diseases have become the focus of attention worldwide. In this review, we discuss several major mechanisms of aging, including DNA damage and repair, free radical oxidation, telomeres and telomerase, mitochondrial damage, inflammation, and their role in neurodegenerative diseases to provide a reference for the prevention of aging and its related diseases.

Mitochondrial dysfunction at the cornerstone of inflammatory exacerbation in aged macrophages

Immunosenescence encompasses multiple age-related adaptations that result in increased susceptibility to infections, chronic inflammatory disorders, and higher mortality risk. Macrophages are key innate cells implicated in inflammatory responses and tissue homeostasis, functions progressively compromised by aging. This process coincides with declining mitochondrial physiology, whose integrity is required to sustain and orchestrate immune responses. Indeed, multiple insults observed in aged macrophages have been implied as drivers of mitochondrial dysfunction, but how this translates into impaired immune function remains sparsely explored. This review provides a perspective on recent studies elucidating the underlying mechanisms linking dysregulated mitochondria homeostasis to immune function in aged macrophages. Genomic stress alongside defective mitochondrial turnover accounted for the progressive accumulation of damaged mitochondria in aged macrophages, thus resulting in a higher susceptibility to excessive mitochondrial DNA (mtDNA) leakage and reactive oxygen species (ROS) production. Increased levels of these mitochondrial products following infection were demonstrated to contribute to exacerbated inflammatory responses mediated by overstimulation of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and cyclic GMP-ATP synthase (cGAS)-stimulator of interferon genes (STING) pathways. While these mechanisms are not fully elucidated, the present evidence provides a promising area to be explored and a renewed perspective of potential therapeutic targets for immunological dysfunction.

Challenges in the Vaccination of the Elderly and Strategies for Improvement

In recent years, the elderly has become a rapidly growing proportion of the world's population as life expectancy is extending. Immunosenescence and inflammaging contribute to the increased risk of chronic non-communicable and acute infectious diseases. Frailty is highly prevalent in the elderly and is associated with an impaired immune response, a higher propensity to infection, and a lower response to vaccines. Additionally, the presence of uncontrolled comorbid diseases in the elderly also contributes to sarcopenia and frailty. Vaccine-preventable diseases that threaten the elderly include influenza, pneumococcal infection, herpes zoster, and COVID-19, which contribute to significant disability-adjusted life years lost. Previous studies had shown that conventional vaccines only yielded suboptimal protection that wanes rapidly in a shorter time. This article reviews published papers on several vaccination strategies that were developed for the elderly to solve these problems: more immunogenic vaccine formulations using larger doses of antigen, stronger vaccine adjuvants, recombinant subunit or protein conjugated vaccines, newly developed mRNA vaccines, giving booster shots, and exploring alternative routes of administration. Included also are several publications on senolytic medications under investigation to boost the immune system and vaccine response in the elderly. With all those in regard, the currently recommended vaccines for the elderly are presented.

Immunology of Aging: the Birth of Inflammaging

The inflammaging concept was introduced in 2000 by Prof. Franceschi. This was an evolutionary or rather a revolutionary conceptualization of the immune changes in response to a lifelong stress. This conceptualization permitted to consider the lifelong proinflammatory process as an adaptation which could eventually lead to either beneficial or detrimental consequences. This dichotomy is influenced by both the genetics and the environment. Depending on which way prevails in an individual, the outcome may be healthy longevity or pathological aging burdened with aging-related diseases. The concept of inflammaging has also revealed the complex, systemic nature of aging. Thus, this conceptualization opens the way to consider age-related processes in their complexity, meaning that not only the process but also all counter-processes should be considered. It has also opened the way to add new concepts to the original one, leading to better understanding of the nature of inflammaging and of aging itself. Finally, it showed the way towards potential multimodal interventions involving a holistic approach to optimize the aging process towards a healthy longevity.

Should We Expect an Increase in the Number of Cancer Cases in People with Long COVID?

The relationship between viral infections and the risk of developing cancer is well known. Multiple mechanisms participate in and determine this process. The COVID-19 pandemic caused by the SARS-CoV-2 virus has resulted in the deaths of millions of people worldwide. Although the effects of COVID-19 are limited for most people, a large number of people continue to show symptoms for a long period of time (long COVID). Several studies have suggested that cancer could also be a potential long-term complication of the virus; however, the causes of this risk are not yet well understood. In this review, we investigated arguments that could support or reject this possibility.

Inflammaging as a target for healthy ageing

Life expectancy has been on the rise for the past few decades, but healthy life expectancy has not kept pace, leading to a global burden of age-associated disorders. Advancing age is accompanied by a chronic increase in basal systemic inflammation, termed inflammaging, contributing towards an increased risk of developing chronic diseases in old age. This article reviews the recent literature to formulate hypotheses regarding how age-associated inflammaging plays a crucial role in driving chronic diseases and ill health in older adults. Here, we discuss how non-pharmacological intervention strategies (diet, nutraceutical supplements, phytochemicals, physical activity, microbiome-based therapies) targeting inflammaging restore health in older adults. We also consider alternative existing pharmacological interventions (Caloric restriction mimetics, p38 mitogen-activated protein kinase inhibitors) and explore novel targets (senolytics) aimed at combating inflammaging and optimising the ageing process to increase healthy lifespan.

Antifragility and antiinflammaging: Can they play a role for a healthy longevity?

One of the most exciting challenges of the research on aging is to explain how the environmental factors interact with the genetic background to modulate the chances to reach the extreme limit of human life in healthy conditions. The complex epigenetic mechanisms can explain both the interaction between DNA and environmental factors, and the long-distance persistence of lifestyle effects, due to the so called "epigenetic memory". One of the most extensively investigated theories on aging focuses on the inflammatory responses, suggesting that the age-related progression of low-grade and therefore for long time subclinical, chronic, systemic, inflammatory process, named "inflammaging", could be the most relevant risk factor for the development and progression of the most common age-related diseases and ultimately of death. The results of many studies on long-lived people, especially on centenarians, suggested that healthy old people can cope with inflammaging upregulating the antiinflammaging responses. Overall, a genetic make-up coding for a strong antiinflammaging response and an age-related ability to remodel key metabolic pathways to cope with a plethora of antigens and stressors seem to be the best ways for reach the extreme limit of human lifespan in health status. In this scenario, we wondered if the antifragility concept, recently developed in the framework of business and risk analysis, could add some information to disentangle the heterogeneous nature of the aging process in human. The antifragility is the property of the complex systems to increase their performances because of high stress. Based on this theory we were wondering if some subjects could be able to modulate faster than others their epigenome to cope with a plethora of stressors during life, probably modulating the inflammatory and anti-inflammatory responses. In this framework, antifragility could share some common mechanisms with anti-inflammaging, modulating the ability to restrain the inflammatory responses, so that antifragility and antiinflammaging could be viewed as different pieces of the same puzzle, both impinging upon the chances to travel along the healthy aging trajectory.

Translational research into frailty from bench to bedside: Salivary biomarkers for inflammaging

Frailty is a complex physiological syndrome associated with adverse ageing and decreased physiological reserves. Frailty leads to cognitive and physical disability and is a significant cause of morbidity, mortality and economic costs. The underlying cause of frailty is multifaceted, including immunosenescence and inflammaging, changes in microbiota and metabolic dysfunction. Currently, salivary biomarkers are used as early predictors for some clinical diseases, contributing to the effective prevention and treatment of diseases, including frailty. Sample collection for salivary analysis is non-invasive and simple, which are paramount factors for testing in the vulnerable frail population. The aim of this review is to describe the current knowledge on the association between frailty and the inflammatory process and discuss methods to identify putative biomarkers in salivary fluids to predict this syndrome. This study describes the relationship between i.-inflammatory process and frailty; ii.-infectious, chronic, skeletal, metabolic and cognitive diseases with inflammation and frailty; iii.-inflammatory biomarkers and salivary fluids. There is a limited number of previous studies focusing on the analysis of inflammatory salivary biomarkers and frailty syndrome; hence, the study of salivary fluids as a source for biomarkers is an open area of research with the potential to address the increasing demands for frailty-associated biomarkers.

cGAS-STING pathway as a potential trigger of immunosenescence and inflammaging

Aging is associated with an increased incidence of autoimmune diseases, despite the progressive decline of immune responses (immunosenescence). This apparent paradox can be explained by the age-related chronic low-grade systemic inflammation (inflammaging) and progressive dysregulation of innate signaling. During cellular aging, there is an accumulation of damaged DNA in the cell's cytoplasm, which serves as ubiquitous danger-associated molecule, promptly recognized by DNA sensors. For instance, the free cytoplasmic DNA can be recognized, by DNA-sensing molecules like cGAS-STING (cyclic GMP-AMP synthase linked to a stimulator of interferon genes), triggering transcriptional factors involved in the secretion of pro-inflammatory mediators. However, the contribution of this pathway to the aging immune system remains largely unknown. Here, we highlight recent advances in understanding the biology of the cGAS-STING pathway, its influence on the senescence-associated secretory phenotype (SASP), and its modulation of the immune system during sterile inflammation. We propose that this important stress sensor of DNA damage is also a trigger of immunosenescence and inflammaging.

The Relationship between Reactive Oxygen Species and the cGAS/STING Signaling Pathway in the Inflammaging Process

During Inflammaging, a dysregulation of the immune cell functions is generated, and these cells acquire a senescent phenotype with an increase in pro-inflammatory cytokines and ROS. This increase in pro-inflammatory molecules contributes to the chronic inflammation and oxidative damage of biomolecules, classically observed in the Inflammaging process. One of the most critical oxidative damages is generated to the host DNA. Damaged DNA is located out of the natural compartments, such as the nucleus and mitochondria, and is present in the cell's cytoplasm. This DNA localization activates some DNA sensors, such as the cGAS/STING signaling pathway, that induce transcriptional factors involved in increasing inflammatory molecules. Some of the targets of this signaling pathway are the SASPs. SASPs are secreted pro-inflammatory molecules characteristic of the senescent cells and inducers of ROS production. It has been suggested that oxidative damage to nuclear and mitochondrial DNA generates activation of the cGAS/STING pathway, increasing ROS levels induced by SASPs. These additional ROS increase oxidative DNA damage, causing a loop during the Inflammaging. However, the relationship between the cGAS/STING pathway and the increase in ROS during Inflammaging has not been clarified. This review attempt to describe the potential connection between the cGAS/STING pathway and ROS during the Inflammaging process, based on the current literature, as a contribution to the knowledge of the molecular mechanisms that occur and contribute to the development of the considered adaptative Inflammaging process during aging.

Emerging cellular senescence-centric understanding of immunological aging and its potential modulation through dietary bioactive components

Immunological aging is strongly associated with the observable deleterious effects of human aging. Our understanding of the causes, effects, and therapeutics of aging immune cells has long been considered within the sole purview of immunosenescence. However, it is being progressively realized that immunosenescence may not be the only determinant of immunological aging. The cellular senescence-centric theory of aging proposes a more fundamental and specific role of immune cells in regulating senescent cell (SC) burden in aging tissues that has augmented the notion of senescence immunotherapy. Now, in addition, several emerging studies are suggesting that cellular senescence itself may be prevalent in aging immune cells, and that senescent immune cells exhibiting characteristic markers of cellular senescence, similar to non-leucocyte cells, could be among the key drivers of various facets of physiological aging. The present review integrates the current knowledge related to immunosenescence and cellular senescence in immune cells per se, and aims at providing a cohesive overview of these two phenomena and their significance in immunity and aging. We present evidence and rationalize that understanding the extent and impact of cellular senescence in immune cells vis-à-vis immunosenescence is necessary for truly comprehending the notion of an 'aged immune cell'. In addition, we also discuss the emerging significance of dietary factors such as phytochemicals, probiotic bacteria, fatty acids, and micronutrients as possible modulators of immunosenescence and cellular senescence. Evidence and opportunities related to nutritional bioactive components and immunological aging have been deliberated to augment potential nutrition-oriented immunotherapy during aging.

Targeting Immune Senescence in Atherosclerosis

Atherosclerosis is one of the main underlying causes of cardiovascular diseases (CVD). It is associated with chronic inflammation and intimal thickening as well as the involvement of multiple cell types including immune cells. The engagement of innate or adaptive immune response has either athero-protective or atherogenic properties in exacerbating or alleviating atherosclerosis. In atherosclerosis, the mechanism of action of immune cells, particularly monocytes, macrophages, dendritic cells, and B- and T-lymphocytes have been discussed. Immuno-senescence is associated with aging, viral infections, genetic predispositions, and hyperlipidemia, which contribute to atherosclerosis. Immune senescent cells secrete SASP that delays or accelerates atherosclerosis plaque growth and associated pathologies such as aneurysms and coronary artery disease. Senescent cells undergo cell cycle arrest, morphological changes, and phenotypic changes in terms of their abundances and secretome profile including cytokines, chemokines, matrix metalloproteases (MMPs) and Toll-like receptors (TLRs) expressions. The senescence markers are used in therapeutics and currently, senolytics represent one of the emerging treatments where specific targets and clearance of senescent cells are being considered as therapy targets for the prevention or treatment of atherosclerosis.

Immunosenescence, aging and successful aging

Aging induces a series of immune related changes, which is called immunosenescence, playing important roles in many age-related diseases, especially neurodegenerative diseases, tumors, cardiovascular diseases, autoimmune diseases and coronavirus disease 2019(COVID-19). However, the mechanism of immunosenescence, the association with aging and successful aging, and the effects on diseases are not revealed obviously. In order to provide theoretical basis for preventing or controlling diseases effectively and achieve successful aging, we conducted the review and found that changes of aging-related phenotypes, deterioration of immune organ function and alterations of immune cell subsets participated in the process of immunosenescence, which had great effects on the occurrence and development of age-related diseases.

The Role of Immunosenescence in Cerebral Small Vessel Disease: A Review

Cerebral small vessel disease (CSVD) is one of the most important causes of vascular dementia. Immunosenescence and inflammatory response, with the involvement of the cerebrovascular system, constitute the basis of this disease. Immunosenescence identifies a condition of deterioration of the immune organs and consequent dysregulation of the immune response caused by cellular senescence, which exposes older adults to a greater vulnerability. A low-grade chronic inflammation status also accompanies it without overt infections, an "inflammaging" condition. The correlation between immunosenescence and inflammaging is fundamental in understanding the pathogenesis of age-related CSVD (ArCSVD). The production of inflammatory mediators caused by inflammaging promotes cellular senescence and the decrease of the adaptive immune response. Vice versa, the depletion of the adaptive immune mechanisms favours the stimulation of the innate immune system and the production of inflammatory mediators leading to inflammaging. Furthermore, endothelial dysfunction, chronic inflammation promoted by senescent innate immune cells, oxidative stress and impairment of microglia functions constitute, therefore, the framework within which small vessel disease develops: it is a concatenation of molecular events that promotes the decline of the central nervous system and cognitive functions slowly and progressively. Because the causative molecular mechanisms have not yet been fully elucidated, the road of scientific research is stretched in this direction, seeking to discover other aberrant processes and ensure therapeutic tools able to enhance the life expectancy of people affected by ArCSVD. Although the concept of CSVD is broader, this manuscript focuses on describing the neurobiological basis and immune system alterations behind cerebral aging. Furthermore, the purpose of our work is to detect patients with CSVD at an early stage, through the evaluation of precocious MRI changes and serum markers of inflammation, to treat untimely risk factors that influence the burden and the worsening of the cerebral disease.

Aging gut microbiota of wild macaques are equally diverse, less stable, but progressively personalized

BACKGROUND

Pronounced heterogeneity of age trajectories has been identified as a hallmark of the gut microbiota in humans and has been explained by marked changes in lifestyle and health condition. Comparatively, age-related personalization of microbiota is understudied in natural systems limiting our comprehension of patterns observed in humans from ecological and evolutionary perspectives.

RESULTS

Here, we tested age-related changes in the diversity, stability, and composition of the gut bacterial community using 16S rRNA gene sequencing with dense repeated sampling over three seasons in a cross-sectional age sample of adult female Assamese macaques (Macaca assamensis) living in their natural forest habitat. Gut bacterial composition exhibited a personal signature which became less stable as individuals aged. This lack of stability was not explained by differences in microbiota diversity but rather linked to an increase in the relative abundance of rare bacterial taxa. The lack of age-related changes in core taxa or convergence with age to a common state of the community hampered predicting gut bacterial composition of aged individuals. On the contrary, we found increasing personalization of the gut bacterial composition with age, indicating that composition in older individuals was increasingly divergent from the rest of the population. Reduced direct transmission of bacteria resulting from decreasing social activity may contribute to, but not be sufficient to explain, increasing personalization with age.

CONCLUSIONS

Together, our results challenge the assumption of a constant microbiota through adult life in a wild primate. Within the limits of this study, the fact that increasing personalization of the aging microbiota is not restricted to humans suggests the underlying process to be evolved instead of provoked only by modern lifestyle of and health care for the elderly. Video abstract.

SIRT6 Widely Regulates Aging, Immunity, and Cancer

SIRT6 is a member of the Sir2-like family in mammals. Recent structural and biochemical studies have characterized SIRT6 as having deacetylation, defatty-acylation, and mono-ADP-ribosylation activities, which determine its important regulatory roles during physiological and pathological processes. This review focuses mainly on the regulatory functions of SIRT6 in aging, cancer, and, especially, immunity. Particular attention is paid to studies illustrating the critical role of SIRT6 in the regulation of immune cells from the viewpoints of immunesenescence, immunometabolism, and tumor immunology. Owing to its role in regulating the function of the immune system, SIRT6 can be considered to be a potential therapeutic target for the treatment of diseases.

Immunosenescence and Altered Vaccine Efficiency in Older Subjects: A Myth Difficult to Change

Organismal ageing is associated with many physiological changes, including differences in the immune system of most animals. These differences are often considered to be a key cause of age-associated diseases as well as decreased vaccine responses in humans. The most often cited vaccine failure is seasonal influenza, but, while it is usually the case that the efficiency of this vaccine is lower in older than younger adults, this is not always true, and the reasons for the differential responses are manifold. Undoubtedly, changes in the innate and adaptive immune response with ageing are associated with failure to respond to the influenza vaccine, but the cause is unclear. Moreover, recent advances in vaccine formulations and adjuvants, as well as in our understanding of immune changes with ageing, have contributed to the development of vaccines, such as those against herpes zoster and SARS-CoV-2, that can protect against serious disease in older adults just as well as in younger people. In the present article, we discuss the reasons why it is a myth that vaccines inevitably protect less well in older individuals, and that vaccines represent one of the most powerful means to protect the health and ensure the quality of life of older adults.

NKT-like (CD3 + CD56+) cells differ from T cells in expression level of cellular protective proteins and sensitivity to stimulation in the process of ageing

BACKGROUND

NKT-like cells are T lymphocytes coexpressing several NK cell-associated receptors. They are effector lymphocytes of innate and adaptive immunity, and their number increases with age. The study aimed to analyze the expression of cellular protective proteins, i.e. sirtuin 1 (SIRT1), heat shock protein 70 (HSP70) and manganese superoxide dismutase (SOD2) in NKT-like and T cells of the young ('young', 31 subjects, age range 19-24 years), seniors aged under 85 ('old'; 30 subjects, age range 65-84 years) and seniors aged over 85 ('oldest', 24 subjects, age range 85-94 years). Both NKT-like and T cells were cultured for 48 h and stimulated with IL-2, LPS and PMA with ionomycin and compared with unstimulated control cells.

RESULTS

The oldest seniors varied from the other age groups by significantly increased expression of SIRT1 and HSP70 in both NKT-like and T cells observed in both stimulated and nonstimulated cells. The analyzed lymphocyte populations of the oldest revealed not only the highest expression of these proteins but also insensitivity to all types of applied stimulation. When NKT-like cells were compared to T cells, higher expression of the studied protective proteins was observed in both stimulated and unstimulated NKT-like cells. Neither CD3 + CD56+ nor CD3+ cells revealed elevated expression of SOD2, and these cells responded to stimulation until very advanced age. T cells revealed higher sensitivity to stimulation with IL-2 regarding SIRT1 and HSP70 expression. NKT-like cells were more sensitive to stimulation with PMA and ionomycin concerning the expression of these proteins. IL-2 did not induce a significant increase in SOD2 expression in the studied age groups.

CONCLUSIONS

The oldest seniors developed an adaptive stress response in both T and NKT-like cells regarding the expression of SIRT1 and HSP70, which was increased and insensitive to further stimulation in contrast to SOD2, which showed a more inducible pattern of expression. CD3 + CD56+ cells exhibited higher expression of cellular protective proteins than CD3+ cells in both stimulated and control, nonstimulated cells. NKT-like and T cells showed a distinct sensitivity to the applied stimulatory factors in the respective age groups.

Does Inflammation Contribute to Cancer Incidence and Mortality during Aging? A Conceptual Review

Aging is associated with chronic low-grade inflammation, cancer incidence and mortality. As inflammation contributes to cancer initiation and progression, one could hypothesize that age-associated chronic low-grade inflammation contributes to the increase in cancer incidence and/or mortality observed during aging. Here, we review the evidence supporting this hypothesis: (1) epidemiological associations between biomarkers of systemic inflammation and cancer incidence and mortality in older people, (2) therapeutic clues suggesting that targeting inflammation could reduce cancer incidence and mortality and (3) experimental evidence from animal models highlighting inflammation as a link between various mechanisms of aging and cancer initiation and progression. Despite a large body of literature linking aging, inflammation and cancer, convincing evidence for the clear implication of specific inflammatory pathways explaining cancer incidence or mortality during aging is still lacking. Further dedicated research is needed to fill these gaps in evidence and pave the way for the development of applications in clinical care.

Aging Relevant Metabolite Itaconate Inhibits Inflammatory Bone Loss

Progressive bone loss during aging makes osteoporosis one of the most common and life impacting conditions in geriatric populations. The bone homeostasis is maintained through persistent remodeling mediated by bone-forming osteoblast and bone-resorbing osteoclast. Inflammaging, a condition characterized by increased pro-inflammatory markers in the blood and other tissues during aging, has been reported to be associated with skeletal stem/progenitor cell dysfunction, which will result in impaired bone formation. However, the role of age-related inflammation and metabolites in regulation of osteoclast remains largely unknown. In the present study, we observed dichotomous phenotypes of anti-inflammatory metabolite itaconate in responding to inflammaging. Itaconate is upregulated in macrophages during aging but has less reactivity in responding to RANKL stimulation in aged macrophages. We confirmed the inhibitory effect of itaconate in regulating osteoclast differentiation and activation, and further verified the rescue role of itaconate in lipopolysaccharides induced inflammatory bone loss animal model. Our findings revealed that itaconate is a crucial regulatory metabolite during inflammaging that inhibits osteoclast to maintain bone homeostasis.

Immune system aging and the aging-related diseases in the COVIID-19 era

The interest in the process of aging, and specifically in how aging affects the working of our immune system, has recently enormously grown among both specialists (immunologists and gerontologists) and representatives of other disciplines of health sciences. An obvious reason for this interest is the current pandemics of COVID-19, known to affect the elderly more than younger people. In this paper current knowledge about mechanisms and complex facets of human immune system aging is presented, stemming from the knowledge about the working of various parts of the immune system, and leading to understanding of immunological mechanisms of chronic, inflammatory, aging-related diseases and of COVID-19.

Train the Trainer: Hematopoietic Stem Cell Control of Trained Immunity

Recent evidence shows that innate immune cells, in addition to B and T cells, can retain immunological memory of their encounters and afford long-term resistance against infections in a process known as 'trained immunity'. However, the duration of the unspecific protection observed in vivo is poorly compatible with the average lifespan of innate immune cells, suggesting the involvement of long-lived cells. Accordingly, recent studies demonstrate that hematopoietic stem and progenitor cells (HSPCs) lay at the foundation of trained immunity, retaining immunological memory of infections and giving rise to a "trained" myeloid progeny for a long time. In this review, we discuss the research demonstrating the involvement of HSPCs in the onset of long-lasting trained immunity. We highlight the roles of specific cytokines and Toll-like receptor ligands in influencing HSPC memory phenotypes and the molecular mechanisms underlying trained immunity HSPCs. Finally, we discuss the potential benefits and drawbacks of the long-lasting trained immune responses, and describe the challenges that the field is facing.

Perspectives on the dynamic implications of cellular senescence and immunosenescence on macrophage aging biology

An intricate relationship between impaired immune functions and the age-related accumulation of tissue senescent cells is rapidly emerging. The immune system is unique as it undergoes mutually inclusive and deleterious processes of immunosenescence and cellular senescence with advancing age. While factors inducing immunosenescence and cellular senescence may be shared, however, both these processes are fundamentally different which holistically influence the aging immune system. Our understanding of the biological impact of immunosenescence is relatively well-understood, but such knowledge regarding cellular senescence in immune cells, especially in the innate immune cells such as macrophages, is only beginning to be elucidated. Tissue-resident macrophages are long-lived, and while functioning in tissue-specific and niche-specific microenvironments, senescence in macrophages can be directly influenced by senescent host cells which may impact organismal aging. In addition, evidence of age-associated immunometabolic changes as drivers of altered macrophage phenotype and functions such as inflamm-aging is also emerging. The present review describes the emerging impact of cellular senescence vis-à-vis immunosenescence in aging macrophages, its biological relevance with other senescent non-immune cells, and known immunometabolic regulators. Gaps in our present knowledge, as well as strategies aimed at understanding cellular senescence and its therapeutics in the context of macrophages, have been reviewed.

Resistance exercise intervention on muscular strength and power, and functional capacity in acute hospitalized older adults: a systematic review and meta-analysis of 2498 patients in 7 randomized clinical trials

To date, no meta-analytical study evaluating the benefits of resistance exercise intervention on muscular strength and power and functional capacity in acute hospitalized older adults was conducted. Then, to synthesize the emerging evidence on the effects of resistance exercise intervention on muscular strength and power and functional capacity in acute hospitalized older adults, two independent authors performed a systematic search (PubMed, Scopus, Web of Science, and SciELO) until January 2021. Randomized clinical trials were included regarding the effects of resistance exercise and hospital usual care. The Cochrane Collaboration assessment tool was used to analyze the risk of bias. The comparisons included muscular strength (isometric handgrip strength and one-repetition maximum test of leg press), muscular power (output during leg press exercise), and functional capacity (timed-up-and-go, and short physical performance battery). Resistance exercise intervention increased muscular strength (isometric handgrip strength: mean difference = 2.50 kg, 95% confidence interval (CI) = 1.33, 3.67; and one-repetition maximum test of leg press: mean difference = 19.28 kg, 95% confidence interval = 14.70, 23.86) and muscular power (mean difference = 29.52 W, 95% confidence interval = 28.84, 30.21), and functional capacity (timed-up-and-go: mean difference = 3.40 s, 95% confidence interval = 0.47, 6.36; and short physical performance battery: mean difference = 1.29 points, 95% confidence interval = 0.10, 2.48) at discharge compared with hospital usual care. This meta-analysis endorses the increase of muscular strength and power gains and improving the functional capacity in favor of resistance exercise intervention in acute hospitalized older adults. TRIAL REGISTRATION : https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020203658.

Safety of Immune Checkpoint Inhibitors in Elderly Patients: An Observational Study

BACKGROUND

Immunotherapy has completely changed the treatment of solid tumors. Although immune checkpoint inhibitors (ICIs) seem to be an appealing alternative to chemotherapy, especially in elderly patients, due to a more tolerable toxicity profile, they can lead to a peculiar variety of immune-related adverse events (irAEs). However, data on tolerability and outcome of ICIs in the elderly are lacking due to poor accrual in clinical trials of these patients.

METHODS

We performed a retro-prospective analysis on patients treated with single agent anti-PD-L1/PD-1 at the Clinical Oncology Unit, Careggi University Hospital, from March 2016 to March 2020. Data on the treatment responses, type and severity of irAEs, as well as the corticosteroids (CCS) dosage used for irAEs and the discontinuation rate, were described per each patient, according to two different age-based cohorts of patients (< or ≥70 years).

RESULTS

We reported a lower incidence of all-grade toxicity in elderly compared to younger patients (64.9% vs. 44.9%, p = 0.018). The two age-cohorts showed a different profile of irAEs. Endocrine irAEs were significantly higher in younger patients (39.7% vs. 21.7%, p = 0.002), while dermatologic toxicities were more common in the older group (35.0% vs. 11.3%, p = 0.047). Use of CCS and treatment discontinuation rate do not differ significantly between the two age groups.

CONCLUSION

Our findings suggest that treatment with ICIs in elderly populations is safe and feasible. Patients over 70 years are more prone to develop skin irAEs, while younger patients are more subject to experience endocrine toxicities.

Immunometabolic responses according to physical fitness status and lifelong exercise during aging: New roads for exercise immunology

Molecules such as cytokines, energetic substrates, and hormones found in the immune cell environment, especially lymphocytes and monocytes, are crucial for directing energy metabolism. In turn, changes in energy metabolism occur in a synchronized manner with the activation of certain signaling pathways, thereby this crosstalk is responsible for determining the functionality of immune cells. The immunometabolism field has grown over time and that is becoming increasingly promising in several populations; here we discuss the mechanisms involved in sedentary and physically active middle-aged individuals and master athletes. In this context, this review shows that the physical activity status and lifelong exercise seems to be good strategies for the promotion of metabolic and functional adaptations in T lymphocytes and monocytes, counteracting inflammatory environments caused by expanded adipose tissue and sedentary behavior, as well as delaying the immunosenescence caused by aging.

Hyperactivation of monocytes and macrophages in MCI patients contributes to the progression of Alzheimer's disease

Background

Alzheimer’s disease (AD) is the most common neurodegenerative disease ultimately manifesting as clinical dementia. Despite considerable effort and ample experimental data, the role of neuroinflammation related to systemic inflammation is still unsettled. While the implication of microglia is well recognized, the exact contribution of peripheral monocytes/macrophages is still largely unknown, especially concerning their role in the various stages of AD.

Objectives

AD develops over decades and its clinical manifestation is preceded by subjective memory complaints (SMC) and mild cognitive impairment (MCI); thus, the question arises how the peripheral innate immune response changes with the progression of the disease. Therefore, to further investigate the roles of monocytes/macrophages in the progression of AD we assessed their phenotypes and functions in patients at SMC, MCI and AD stages and compared them with cognitively healthy controls. We also conceptualised an idealised mathematical model to explain the functionality of monocytes/macrophages along the progression of the disease.

Results

We show that there are distinct phenotypic and functional changes in monocyte and macrophage populations as the disease progresses. Higher free radical production upon stimulation could already be observed for the monocytes of SMC patients. The most striking results show that activation of peripheral monocytes (hyperactivation) is the strongest in the MCI group, at the prodromal stage of the disease. Monocytes exhibit significantly increased chemotaxis, free radical production, and cytokine production in response to TLR2 and TLR4 stimulation.

Conclusion

Our data suggest that the peripheral innate immune system is activated during the progression from SMC through MCI to AD, with the highest levels of activation being in MCI subjects and the lowest in AD patients. Some of these parameters may be used as biomarkers, but more holistic immune studies are needed to find the best period of the disease for clinical intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12979-021-00236-x.

The dual role of the immune system in the course of COVID-19. The fatal impact of the aging immune system

COVID-19 is a highly contagious respiratory disease caused by the novel coronavirus SARS-CoV-2. Since October 2020 the second wave of the pandemic has been observed around the world, as pathogen specific herd immunity has not been built yet. Moreover, the current, more contagious pathogen carrying the D614G mutation has become the globally dominant form of SARS-CoV-2. In this article we present the current state of knowledge on the impact of ACE2 and the reninangiotensin system (RAS) and the innate immune system on different outcomes of COVID-19. Especially, we point out the dual role of the immune system and ACE2 in pathogenesis of the disease. Namely, at the initial stage of the infection anti-viral activity of innate immunity is responsible for inhibition of SARS-CoV-2 replication. On the other hand, a dysregulated immune response may cause the detrimental hyperinflammation ("cytokine storm") responsible for the severe course of the disease. Concomitantly, we analyse the roles of ACE2 in both facilitation of infection and abrogation of its effects, as the major cellular entry receptor for SARS-CoV-2 and an important enzyme responsible for tissue protection, respectively. Finally, we discuss the dominant impact of aging on the fatal outcome of COVID-19.

SARS-CoV-2 infection represents a high risk for the elderly: analysis of pathogenesis

As people get older, age-related alterations occur that lead to increased susceptibility to disease. In the current COVID-19 pandemic, older people are particularly susceptible to a SARS-CoV-2 infection developing into severe disease. The objective of this review was to examine the literature regarding factors that may explain the tendency of this population to develop severe COVID-19. Research articles considered in this review were searched for in EMBASE, PubMed, and Web of Science from December 2019 to December 2020. Citations were screened by two independent reviewers. Studies of the immune system in older individuals found alterations in both the adaptive and innate immune systems. The adaptive system is depressed in its functions, and the innate system is in a pro-inflammatory state that can lead to chronic disease. This pro-inflammatory state may be related to a severe course of disease in COVID-19. This review shows that the level of evidence supporting an association between immune alterations in the elderly and susceptibly to severe progression of SARS-CoV-2 infection is generally consistent. Preventive measures such as early antiviral treatment are of key importance for prevention of severe progression of COVID19.

Probing the Interface of HIV and Inflammaging

PURPOSE OF REVIEW

Systemic inflammation increases as a consequence of aging (inflammaging) and contributes to age-related morbidities. Inflammation in people living with HIV is elevated compared with the general population even after prolonged suppression of viremia with anti-retroviral therapy. Mechanisms that contribute to inflammation during aging and in treated HIV disease are potentially interactive, leading to an exaggerated inflammatory phenotype in people with HIV.

RECENT FINDINGS

Recent studies highlight roles for anti-retroviral therapy, co-infections, immune system alterations, and microbiome perturbations as important contributors to HIV-associated inflammation. These factors likely contribute to increased risk of age-related morbidities in people living with HIV. Understanding mechanisms that exaggerate the inflammaging process in people with HIV may lead to improved intervention strategies, ultimately, extending both lifespan and healthspan.

Macrophage function in the elderly and impact on injury repair and cancer

Older age is associated with deteriorating health, including escalating risk of diseases such as cancer, and a diminished ability to repair following injury. This rise in age-related diseases/co-morbidities is associated with changes to immune function, including in myeloid cells, and is related to immunosenescence. Immunosenescence reflects age-related changes associated with immune dysfunction and is accompanied by low-grade chronic inflammation or inflammageing. This is characterised by increased levels of circulating pro-inflammatory cytokines such as tumor necrosis factor (TNF), interleukin (IL)-1β and IL-6. However, in healthy ageing, there is a concomitant age-related escalation in anti-inflammatory cytokines such as transforming growth factor-β1 (TGF-β1) and IL-10, which may overcompensate to regulate the pro-inflammatory state. Key inflammatory cells, macrophages, play a role in cancer development and injury repair in young hosts, and we propose that their role in ageing in these scenarios may be more profound. Imbalanced pro- and anti-inflammatory factors during ageing may also have a significant influence on macrophage function and further impact the severity of age-related diseases in which macrophages are known to play a key role. In this brief review we summarise studies describing changes to inflammatory function of macrophages (from various tissues and across sexes) during healthy ageing. We also describe age-related diseases/co-morbidities where macrophages are known to play a key role, focussed on injury repair processes and cancer, plus comment briefly on strategies to correct for these age-related changes.

Targeting Impaired Antimicrobial Immunity in the Brain for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia and aging is the most common risk factor for developing the disease. The etiology of AD is not known but AD may be considered as a clinical syndrome with multiple causal pathways contributing to it. The amyloid cascade hypothesis, claiming that excess production or reduced clearance of amyloid-beta (Aβ) and its aggregation into amyloid plaques, was accepted for a long time as the main cause of AD. However, many studies showed that Aβ is a frequent consequence of many challenges/pathologic processes occurring in the brain for decades. A key factor, sustained by experimental data, is that low-grade infection leading to production and deposition of Aβ, which has antimicrobial activity, precedes the development of clinically apparent AD. This infection is chronic, low grade, largely clinically silent for decades because of a nearly efficient antimicrobial immune response in the brain. A chronic inflammatory state is induced that results in neurodegeneration. Interventions that appear to prevent, retard or mitigate the development of AD also appear to modify the disease. In this review, we conceptualize further that the changes in the brain antimicrobial immune response during aging and especially in AD sufferers serve as a foundation that could lead to improved treatment strategies for preventing or decreasing the progression of AD in a disease-modifying treatment.

Thymus involution sets the clock of the aging T-cell landscape: Implications for declined immunity and tissue repair

Aging is generally characterized as a gradual increase in tissue damage, which is associated with senescence and chronic systemic inflammation and is evident in a variety of age-related diseases. The extent to which such tissue damage is a result of a gradual decline in immune regulation, which consequently compromises the capacity of the body to repair damages, has not been fully explored. Whereas CD4 T lymphocytes play a critical role in the orchestration of immunity, thymus involution initiates gradual changes in the CD4 T-cell landscape, which may significantly compromise tissue repair. In this review, we describe the lifespan accumulation of specific dysregulated CD4 T-cell subsets and their coevolution with systemic inflammation in the process of declined immunity and tissue repair capacity with age. Then, we discuss the process of thymus involution-which appears to be most pronounced around puberty-as a possible driver of the aging T-cell landscape. Finally, we identify individualized T cell-based early diagnostic biomarkers and therapeutic strategies for age-related diseases.

Effects of cellular senescence on metabolic pathways in non-immune and immune cells

Many cellular stresses induce cellular senescence and the irreversible arrest of cell proliferation in different cell types. Although blocked in their capacity to divide, senescent cells are metabolically active and are characterized by a different metabolic phenotype as compared to non-senescent cells. Changes observed in senescent cells depend from the cell type and lead to an adaptative flexibility in the type of metabolism. This metabolic reprogramming is needed to cope with survival and with the energetic demands of the senescent program that include the increased secretion of senescence-associated secretory phenotype factors.

Extra-cranial factors in the development of Alzheimer's disease

The development of Alzheimer's Disease (AD) likely involves dysfunction in more than one extra-cranial organ system. AD appears to depend on several functional organ impairments that develops frequently during aging: lack of normal hepatic synthesis, defective detoxification of ammonia, gut microbiome dysbiosis, the development of insulin resistance, diminished adrenal production of dehydroepiandrosterone, nutrient depletion, impaired immune processes with persistent chronic neuro-inflammation, and persistent infectious processes are important components of this system-wide disorder. By reviewing these abnormalities in different organ systems, this review intends to suggest that clinical research into the prevention of dementia needs to take this interplay of organ system dysfunction into account. The design of therapeutic interventions needs to address dysfunction in more than one system at a time. We have singled out one aberrant signaling pathway, NF-kB, that seems common to several of the dysfunctional organ systems and suggest some potential interventions that may be effective when combined with others. Clinical research may need to shift from single factor interventions to studies that include multiple simultaneous interventions that restore health in multiple impaired organ systems in the aging human in order to avert future epidemics of AD.

A Perspective on Roles Played by Immunosenescence in the Pathobiology of Alzheimer's Disease

Alzheimer's disease (AD) is a chronic progressive neurodegenerative disorder. Aging is the most significant risk factor for late-onset AD. The age-associated changes in the immune system are termed immunosenescence. A close connection between immunosenescence and AD is increasingly recognized. This article provides an overview of immunosenescence and evidence for its role in the pathogenesis of AD and possible mechanisms as well as the outlook for drug development.

Nutraceuticals-Based Immunotherapeutic Concepts and Opportunities for the Mitigation of Cellular Senescence and Aging: A Narrative Review

The role of increased tissue senescent cell (SC) burden in driving the process of ageing and associated disorders is rapidly gaining attention. Amongst various plausible factors, impairment in immune functions is emerging as a critical regulator of known age-associated accumulation of SC. Immune cells dysfunctions with age are multi-faceted and are uniquely attributed to the independent processes of immunosenescence and cellular senescence which may collectively impair immune system mediated clearance of SC. Moreover, being functionally and phenotypically heterogenic, immune cells are also liable to be affected by senescence microenvironment in other tissues. Therefore, strategies aimed at improving immunosenescence and cellular senescence in immune cells can have pleiotropic effects on ageing physiology including the accumulation of SC. In this regard, nutraceutical's immunomodulatory attributes are well documented which may have implications in developing nutrition-oriented immunotherapeutic approaches against SC. In particular, the three diverse sources of bioactive ingredients, viz., phytochemicals, probiotic bacteria and omega-3-fatty acids have shown promising anti-immunosenescence and anti-cellular senescence potential in immune cells influencing aging and immunity in ways beyond modest stimulation of immune responses. The present narrative review describes the preventive and therapeutic attributes of phytochemicals such as polyphenols, probiotic microbes and omega-3-fatty acids in influencing the emerging nexus of immunosenescence, cellular senescence and SC during aging. Outstanding questions and nutraceuticals-based pro-longevity and niche research areas have been deliberated. Further research using integrative approaches is recommended for developing nutrition-based holistic immunotherapeutic strategies for 'healthy ageing'.

The Challenge by Multiple Environmental and Biological Factors Induce Inflammation in Aging: Their Role in the Promotion of Chronic Disease

The aging process is driven by multiple mechanisms that lead to changes in energy production, oxidative stress, homeostatic dysregulation and eventually to loss of functionality and increased disease susceptibility. Most aged individuals develop chronic low-grade inflammation, which is an important risk factor for morbidity, physical and cognitive impairment, frailty, and death. At any age, chronic inflammatory diseases are major causes of morbimortality, affecting up to 5-8% of the population of industrialized countries. Several environmental factors can play an important role for modifying the inflammatory state. Genetics accounts for only a small fraction of chronic-inflammatory diseases, whereas environmental factors appear to participate, either with a causative or a promotional role in 50% to 75% of patients. Several of those changes depend on epigenetic changes that will further modify the individual response to additional stimuli. The interaction between inflammation and the environment offers important insights on aging and health. These conditions, often depending on the individual's sex, appear to lead to decreased longevity and physical and cognitive decline. In addition to biological factors, the environment is also involved in the generation of psychological and social context leading to stress. Poor psychological environments and other sources of stress also result in increased inflammation. However, the mechanisms underlying the role of environmental and psychosocial factors and nutrition on the regulation of inflammation, and how the response elicited for those factors interact among them, are poorly understood. Whereas certain deleterious environmental factors result in the generation of oxidative stress driven by an increased production of reactive oxygen and nitrogen species, endoplasmic reticulum stress, and inflammation, other factors, including nutrition (polyunsaturated fatty acids) and behavioral factors (exercise) confer protection against inflammation, oxidative and endoplasmic reticulum stress, and thus ameliorate their deleterious effect. Here, we discuss processes and mechanisms of inflammation associated with environmental factors and behavior, their links to sex and gender, and their overall impact on aging.