The impact of ageing on monocytes and macrophages

Sustained exposure to high glucose induces differential expression of cellular senescence markers in murine macrophages but impairs immunosurveillance response to senescent cells secretome

The influence of chronic diseases on various facets of macrophage cellular senescence is poorly understood. This study evaluated the impact of chronic hyperglycemia on the induction of cellular senescence and subsequent immunosurveillance functions in RAW264.7 macrophages. Macrophages were cultured under normal glucose (NG; 5 mM), high glucose (HG; 20 mM), and very high glucose (VHG; 40 mM) conditions and assessed for markers of cellular senescence. Hyperglycemia induced strong upregulation of SA-β-gal activity, and loss of PCNA and Lamin B1 gene expression while markers of cell cycle arrest generally decreased. Non-significant changes in SASP-related proteins were observed while ROS levels slightly decreased and mitochondrial membrane potential increased. Protein concentration on the exosome membrane surface and their stability appeared to increase under hyperglycemic conditions. However, when macrophages were exposed to the secretory media (SM) of senescent preadipocytes, a dramatic increase in the levels of all inflammatory proteins was recorded especially in the VHG group that was also accompanied by upregulation of NF-κB and NLRP3 gene expression. SM treatment to hyperglycemic macrophages activated the TLR-2/Myd88 pathway but decreased the expression of scavenger receptors RAGE, CD36, and Olr-1 while CD44 and CXCL16 expression increased. On exposure to LPS, a strong upregulation in NO, ROS, and inflammatory cytokines was observed. Together, these results suggest that primary markers of cellular senescence are aberrantly expressed under chronic hyperglycemic conditions in macrophages with no significant SASP activation. Nonetheless, hyperglycemia strongly deregulates macrophage functions leading to impaired immunosurveillance of senescent cells and aggravation of inflamm-aging. This work provides novel insights into how hyperglycemia-induced dysfunctions can impact the potency of macrophages to manage senescent cell burden in aging tissues.

Elucidating the role of chemokines in inflammaging associated atherosclerotic cardiovascular diseases

Age-related inflammation or inflammaging is a critical deciding factor of physiological homeostasis during aging. Cardiovascular diseases (CVDs) are exquisitely associated with aging and inflammation and are one of the leading causes of high mortality in the elderly population. Inflammaging comprises dysregulation of crosstalk between the vascular and cardiac tissues that deteriorates the vasculature network leading to development of atherosclerosis and atherosclerotic-associated CVDs in elderly populations. Leukocyte differentiation, migration and recruitment holds a crucial position in both inflammaging and atherosclerotic CVDs through relaying the activity of an intricate network of inflammation-associated protein-protein interactions. Among these interactions, small immunoproteins such as chemokines play a major role in the progression of inflammaging and atherosclerosis. Chemokines are actively involved in lymphocyte migration and severe inflammatory response at the site of injury. They relay their functions via chemokine-G protein-coupled receptors-glycosaminoglycan signaling axis and is a principal part for the detection of age-related atherosclerosis and related CVDs. This review focuses on highlighting the detailed intricacies of the effects of chemokine-receptor interaction and chemokine oligomerization on lymphocyte recruitment and its evident role in clinical manifestations of atherosclerosis and related CVDs. Further, the role of chemokine mediated signaling for formulating next-generation therapeutics against atherosclerosis has also been discussed.

Unraveling the molecular and immunological landscape: Exploring signaling pathways in osteoporosis

Osteoporosis, characterized by compromised bone density and microarchitecture, represents a significant global health challenge, particularly in aging populations. This comprehensive review delves into the intricate signaling pathways implicated in the pathogenesis of osteoporosis, providing valuable insights into the pivotal role of signal transduction in maintaining bone homeostasis. The exploration encompasses cellular signaling pathways such as Wnt, Notch, JAK/STAT, NF-κB, and TGF-β, all of which play crucial roles in bone remodeling. The dysregulation of these pathways is a contributing factor to osteoporosis, necessitating a profound understanding of their complexities to unveil the molecular mechanisms underlying bone loss. The review highlights the pathological significance of disrupted signaling in osteoporosis, emphasizing how these deviations impact the functionality of osteoblasts and osteoclasts, ultimately resulting in heightened bone resorption and compromised bone formation. A nuanced analysis of the intricate crosstalk between these pathways is provided to underscore their relevance in the pathophysiology of osteoporosis. Furthermore, the study addresses some of the most crucial long non-coding RNAs (lncRNAs) associated with osteoporosis, adding an additional layer of academic depth to the exploration of immune system involvement in various types of osteoporosis. Finally, we propose that SKP1 can serve as a potential biomarker in osteoporosis.

As time goes by: Treatment challenges in elderly people with multiple sclerosis

A demographic shift in multiple sclerosis (MS) is leading to an increased number of elderly people with MS (pwMS) and a rise in late-onset MS (LOMS) cases. This shift adds complexity to the treatment management of these patients, due to enhanced treatment-associated risks and the possible interplay between immunosenescence and disease-modifying therapies (DMTs). In the present paper, we performed a systematic review of the current evidence concerning the relationship between aging and treatment management in elderly pwMS. Our literature search identified 35 original studies relevant to this topic. The gathered evidence consistently indicates a diminished efficacy of DMTs in older pwMS, particularly in preventing disability accrual. Against this background, high-efficacy therapies (HETs) appear to show less benefit over moderate-low-efficacy DMTs in older patients. These data mainly derive from observational retrospective studies or meta-analyses conducted on randomized clinical trials (RCTs). RCTs, however, exclude pwMS older than 55 years, limiting our ability to acquire robust evidence regarding this patient group. Regarding treatment discontinuation in elderly pwMS with stable disease, the available data, which mainly focuses on older injectable DMTs, suggests that their suspension appears to be relatively safe in terms of disease activity. Nevertheless, the first RCT specifically targeting treatment discontinuation recently failed to demonstrate the non-inferiority of treatment discontinuation over continuation, in terms of MRI activity. On the other hand, the evidence on the impact of discontinuation on disease progression is more conflicting and less robust. Furthermore, there is an important lack of studies concerning sequestering DMTs and virtually no data on the discontinuation of anti-CD20 monoclonal antibodies. De-escalation strategy is gaining attention as a de-risking approach alternative to complete treatment discontinuation. It may be defined as the decision to shift from HETs to less potent DMTs in elderly pwMS who have a stable disease. This strategy could reduce treatment-related risks, while minimizing the risk of disease activity and progression potentially associated with treatment discontinuation. This approach, however, remains unexplored due to a lack of studies. Given these findings, the present scenario underlines the urgent need for more comprehensive and robust studies to develop optimized, data-driven treatment strategies for elderly pwMS and LOMS, addressing the unique challenges of MS treatment and aging.

Osteoimmunology of Fracture Healing

PURPOSE OF REVIEW

The purpose of this review is to summarize what is known in the literature about the role inflammation plays during bone fracture healing. Bone fracture healing progresses through four distinct yet overlapping phases: formation of the hematoma, development of the cartilaginous callus, development of the bony callus, and finally remodeling of the fracture callus. Throughout this process, inflammation plays a critical role in robust bone fracture healing.

RECENT FINDINGS

At the onset of injury, vessel and matrix disruption lead to the generation of an inflammatory response: inflammatory cells are recruited to the injury site where they differentiate, activate, and/or polarize to secrete cytokines for the purposes of cell signaling and cell recruitment. This process is altered by age and by sex. Bone fracture healing is heavily influenced by the presence of inflammatory cells and cytokines within the healing tissue.

Prognostic accuracy of 70 individual frailty biomarkers in predicting mortality in the Canadian Longitudinal Study on Aging

The frailty index (FI) uses a deficit accumulation approach to derive a single, comprehensive, and replicable indicator of age-related health status. Yet, many researchers continue to seek a single "frailty biomarker" to facilitate clinical screening. We investigated the prognostic accuracy of 70 individual biomarkers in predicting mortality, comparing each with a composite FI. A total of 29,341 individuals from the comprehensive cohort of the Canadian Longitudinal Study on Aging were included (mean, 59.4 ± 9.9 years; 50.3% female). Twenty-three blood-based biomarkers and 47 test-based biomarkers (e.g., physical, cardiac, cardiology) were examined. Two composite FIs were derived: FI-Blood and FI-Examination. Mortality status was ascertained using provincial vital statistics linkages and contact with next of kin. Areas under the curve were calculated to compare prognostic accuracy across models (i.e., age, sex, biomarker, FI) in predicting mortality. Compared to an age-sex only model, the addition of individual biomarkers demonstrated improved model fit for 24/70 biomarkers (11 blood, 13 test-based). Inclusion of FI-Blood or FI-Examination improved mortality prediction when compared to any of the 70 biomarker-age-sex models. Individual addition of seven biomarkers (walking speed, chair rise, time up and go, pulse, red blood cell distribution width, C-reactive protein, white blood cells) demonstrated an improved fit when added to the age-sex-FI model. FI scores had better mortality risk prediction than any biomarker. Although seven biomarkers demonstrated improved prognostic accuracy when considered alongside an FI score, all biomarkers had worse prognostic accuracy on their own. Rather than a single biomarker test, implementation of routine FI assessment in clinical settings may provide a more accurate and reliable screening tool to identify those at increased risk of adverse outcomes.

Macrophages and tumor-associated macrophages in the senescent microenvironment: From immunosuppressive TME to targeted tumor therapy

In-depth studies of the tumor microenvironment (TME) have helped to elucidate its cancer-promoting mechanisms and inherent characteristics. Cellular senescence, which acts as a response to injury and can the release of senescence-associated secretory phenotypes (SASPs). These SASPs release various cytokines, chemokines, and growth factors, remodeling the TME. This continual development of a senescent environment could be associated with chronic inflammation and immunosuppressive TME. Additionally, SASPs could influence the phenotype and function of macrophages, leading to the recruitment of tumor-associated macrophages (TAMs). This contributes to tumor proliferation and metastasis in the senescent microenvironment, working in tandem with immune regulation, angiogenesis, and therapeutic resistance. This comprehensive review covers the evolving nature of the senescent microenvironment, macrophages, and TAMs in tumor development. We also explored the links between chronic inflammation, immunosuppressive TME, cellular senescence, and macrophages. Moreover, we compiled various tumor-specific treatment strategies centered on cellular senescence and the current challenges in cellular senescence research. This study aimed to clarify the mechanism of macrophages and the senescent microenvironment in tumor progression and advance the development of targeted tumor therapies.

Metabolic homeostasis of tissue macrophages across the lifespan

Macrophages are present in almost all organs. Apart from being immune sentinels, tissue-resident macrophages (TRMs) have organ-specific functions that require a specialized cellular metabolism to maintain homeostasis. In addition, organ-dependent metabolic adaptations of TRMs appear to be fundamentally distinct in homeostasis and in response to a challenge, such as infection or injury. Moreover, TRM function becomes aberrant with advancing age, contributing to inflammaging and organ deterioration, and a metabolic imbalance may underlie TRM immunosenescence. Here, we outline current understanding of the particular metabolic states of TRMs across organs and the relevance for their function. Moreover, we discuss the concomitant aging-related decline in metabolic plasticity and functions of TRMs, highlighting potential novel therapeutic avenues to promote healthy aging.

Immunosenescence and inflammaging: Conspiracies against alveolar bone turnover

OBJECTIVE

Inflammaging and immunosenescence are characteristics of senescent immune system alterations. This review provides insights into inflammaging and immunosenescence in periodontitis and focuses on the innerlink of inflammaging and immunosenescence in alveolar bone turnover from a perspective of cell-cell interaction.

METHODS

This review is conducted by a narrative approach to discuss the effect of inflammaging and immunosenescence in aging-related alveolar bone loss. A comprehensive literature research in PubMed and Google was applied to identify reports in English.

RESULTS

Inflammaging is concerned with abnormal M1 polarization and increasing circulating inflammatory cytokines, while immunosenescence involves reduced infection and vaccine responses, depressed antimicrobial function, and infiltration of aged B cells and memory T cells. TLR-mediated inflammaging and altered adaptive immunity significantly affect alveolar bone turnover and aggravate aging-related alveolar bone loss. Besides, energy consumption also plays a vital role in aged immune and skeletal system of periodontitis.

CONCLUSIONS

Senescent immune system exerts a significant function in aging-related alveolar bone loss. Inflammaging and immunosenescence interact functionally and mechanistically, which affects alveolar bone turnover. Therefore, further clinical treatment strategies targeting alveolar bone loss could be based on the specific molecular mechanism connecting inflammaging, immunosenescence, and alveolar bone turnover.

Tumor-Associated Senescent Macrophages, Their Markers, and Their Role in Tumor Microenvironment

Tumor-associated macrophages (TAMs) are an important component of the tumor microenvironment (TME) and the most abundant population of immune cells infiltrating a tumor. TAMs can largely determine direction of anti-tumor immune response by promoting it or, conversely, contribute to formation of an immunosuppressive TME that allows tumors to evade immune control. Through interactions with tumor cells or other cells in the microenvironment and, as a result of action of anti-cancer therapy, macrophages can enter senescence. In this review, we have attempted to summarize information available in the literature on the role of senescent macrophages in tumors. With the recent development of senolytic therapeutic strategies aimed at removing senescent cells from an organism, it seems important to discuss functions of the senescent macrophages and potential role of the senolytic drugs in reprogramming TAMs to enhance anti-tumor immune response and improve efficacy of cancer treatment.

The guardians of pulmonary harmony: alveolar macrophages orchestrating the symphony of lung inflammation and tissue homeostasis

Recent breakthroughs in single-cell sequencing, advancements in cellular and tissue imaging techniques, innovations in cell lineage tracing, and insights into the epigenome collectively illuminate the enigmatic landscape of alveolar macrophages in the lung under homeostasis and disease conditions. Our current knowledge reveals the cellular and functional diversity of alveolar macrophages within the respiratory system, emphasising their remarkable adaptability. By synthesising insights from classical cell and developmental biology studies, we provide a comprehensive perspective on alveolar macrophage functional plasticity. This includes an examination of their ontology-related features, their role in maintaining tissue homeostasis under steady-state conditions and the distinct contribution of bone marrow-derived macrophages (BMDMs) in promoting tissue regeneration and restoring respiratory system homeostasis in response to injuries. Elucidating the signalling pathways within inflammatory conditions, the impact of various triggers on tissue-resident alveolar macrophages (TR-AMs), as well as the recruitment and polarisation of macrophages originating from the bone marrow, presents an opportunity to propose innovative therapeutic approaches aimed at modulating the equilibrium between phenotypes to induce programmes associated with a pro-regenerative or homeostasis phenotype of BMDMs or TR-AMs. This, in turn, can lead to the amelioration of disease outcomes and the attenuation of detrimental inflammation. This review comprehensively addresses the pivotal role of macrophages in the orchestration of inflammation and resolution phases after lung injury, as well as ageing-related shifts and the influence of clonal haematopoiesis of indeterminate potential mutations on alveolar macrophages, exploring altered signalling pathways and transcriptional profiles, with implications for respiratory homeostasis.

Stimuli-Mediated Macrophage Switching, Unraveling the Dynamics at the Nanoplatforms-Macrophage Interface

Macrophages play an essential role in immunotherapy and tissue regeneration owing to their remarkable plasticity and diverse functions. Recent bioengineering developments have focused on using external physical stimuli such as electric and magnetic fields, temperature, and compressive stress, among others, on micro/nanostructures to induce macrophage polarization, thereby increasing their therapeutic potential. However, it is difficult to find a concise review of the interaction between physical stimuli, advanced micro/nanostructures, and macrophage polarization. This review examines the present research on physical stimuli-induced macrophage polarization on micro/nanoplatforms, emphasizing the synergistic role of fabricated structure and stimulation for advanced immunotherapy and tissue regeneration. A concise overview of the research advancements investigating the impact of physical stimuli, including electric fields, magnetic fields, compressive forces, fluid shear stress, photothermal stimuli, and multiple stimulations on the polarization of macrophages within complex engineered structures, is provided. The prospective implications of these strategies in regenerative medicine and immunotherapeutic approaches are highlighted. This review will aid in creating stimuli-responsive platforms for immunomodulation and tissue regeneration.

Border-associated macrophages in the central nervous system

Tissue-resident macrophages play an important role in the local maintenance of homeostasis and immune surveillance. In the central nervous system (CNS), brain macrophages are anatomically divided into parenchymal microglia and non-parenchymal border-associated macrophages (BAMs). Among these immune cell populations, microglia have been well-studied for their roles during development as well as in health and disease. BAMs, mostly located in the choroid plexus, meningeal and perivascular spaces, are now gaining increased attention due to advancements in multi-omics technologies and genetic methodologies. Research on BAMs over the past decade has focused on their ontogeny, immunophenotypes, involvement in various CNS diseases, and potential as therapeutic targets. Unlike microglia, BAMs display mixed origins and distinct self-renewal capacity. BAMs are believed to regulate neuroimmune responses associated with brain barriers and contribute to immune-mediated neuropathology. Notably, BAMs have been observed to function in diverse cerebral pathologies, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, ischemic stroke, and gliomas. The elucidation of the heterogeneity and diverse functions of BAMs during homeostasis and neuroinflammation is mesmerizing, since it may shed light on the precision medicine that emphasizes deep insights into programming cues in the unique brain immune microenvironment. In this review, we delve into the latest findings on BAMs, covering aspects like their origins, self-renewal capacity, adaptability, and implications in different brain disorders.

Alterations in metabolic pathways: a bridge between aging and weaker innate immune response

Aging is a time-dependent progressive physiological process, which results in impaired immune system function. Age-related changes in immune function increase the susceptibility to many diseases such as infections, autoimmune diseases, and cancer. Different metabolic pathways including glycolysis, tricarboxylic acid cycle, amino acid metabolism, pentose phosphate pathway, fatty acid oxidation and fatty acid synthesis regulate the development, differentiation, and response of adaptive and innate immune cells. During aging all these pathways change in the immune cells. In addition to the changes in metabolic pathways, the function and structure of mitochondria also have changed in the immune cells. Thereby, we will review changes in the metabolism of different innate immune cells during the aging process.

Senescent cell-derived extracellular vesicles as potential mediators of innate immunosenescence and inflammaging

Ageing is accompanied by a decline in immune function (immunosenescence), increased inflammation (inflammaging), and more senescent cells which together contribute to age-related disease and infection susceptibility. The innate immune system is the front-line defence against infection and cancer and is also involved in the removal of senescent cells, so preventing innate immunosenescence and inflammaging is vital for health in older age. Extracellular vesicles (EVs) modulate many aspects of innate immune function, including chemotaxis, anti-microbial responses, and immune regulation. Senescent cell derived EVs (SEVs) have different cargo to that of non-senescent cell derived EVs, suggesting alterations in EV cargo across the lifespan may influence innate immune function, possibly contributing to immunosenescence and inflammaging. Here we review current understanding of the potential impact of miRNAs, lipids and proteins, found in higher concentrations in SEVs, on innate immune functions and inflammation to consider whether SEVs are potential influencers of innate immunosenescence and inflammaging. Furthermore, senolytics have demonstrated an ability to return plasma EV content closer to that of non-senescent EVs, therefore the potential use of senotherapeutics (senolytics and senostatics) to ameliorate the effects of SEVs on immunosenescence and inflammaging is also considered as a possible strategy for extending health-span in older adults.

Impact of Immunosenescence in Older Kidney Transplant Recipients: Associated Clinical Outcomes and Possible Risk Stratification for Immunosuppression Reduction

The number of older individuals receiving a kidney transplant as replacement therapy has significantly increased in the past decades and this increase is expected to continue. Older patients have a lower rate of acute rejection but an increased incidence of death with a functioning graft. Several factors, including an increased incidence of infections, post-transplant malignancy and cardiovascular comorbidity and mortality, contribute to this increased risk. Notwithstanding, kidney transplantation is still the best form of kidney replacement therapy in all patients with chronic kidney disease, including in older individuals. The best form of immunosuppression and the optimal dose of these medications in older recipients remains a topic of discussion. Pharmacological studies have usually excluded older patients and when included, patients were highly selected and their numbers insignificant to draw a reasonable conclusion. The reduced incidence of acute rejection in older recipients has largely been attributed to immunosenescence. Immunosenescence refers to the aging of the innate and adaptive immunity, accumulating in phenotypic and functional changes. These changes influences the response of the immune system to new challenges. In older individuals, immunosenescence is associated with increased susceptibility to infectious pathogens, a decreased response after vaccinations, increased risk of malignancies and cardiovascular morbidity and mortality. Chronic kidney disease is associated with premature immunosenescent changes, and these are independent of aging. The immunosenescent state is associated with low-grade sterile inflammation termed inflammaging. This chronic low-grade inflammation triggers a compensatory immunosuppressive state to avoid further tissue damage, leaving older individuals with chronic kidney disease in an immune-impaired state before kidney transplantation. Immunosuppression after transplantation may further enhance progression of this immunosenescent state. This review covers the role of immunosenescence in older kidney transplant recipients and it details present knowledge of the changes in chronic kidney disease and after transplantation. The impact of immunosuppression on the progression and complications of an immunosenescent state are discussed, and the future direction of a possible clinical implementation of immunosenescence to individualize/reduce immunosuppression in older recipients is laid out.

Immune aging: biological mechanisms, clinical symptoms, and management in lung transplant recipients

While chronologic age can be precisely defined, clinical manifestations of advanced age occur in different ways and at different rates across individuals. The observed phenotype of advanced age likely reflects a superposition of several biological aging mechanisms which have gained increasing attention as the world contends with an aging population. Even within the immune system, there are multiple age-associated biological mechanisms at play, including telomere dysfunction, epigenetic dysregulation, immune senescence programs, and mitochondrial dysfunction. These biological mechanisms have associated clinical syndromes, such as telomere dysfunction leading to short telomere syndrome (STS), and optimal patient management may require recognition of biologically based aging syndromes. Within the clinical context of lung transplantation, select immune aging mechanisms are particularly pronounced. Indeed, STS is increasingly recognized as an indication for lung transplantation. At the same time, common aging phenotypes may be evoked by the stress of transplantation because lung allografts face a potent immune response, necessitating higher levels of immune suppression and associated toxicities, relative to other solid organs. Age-associated conditions exacerbated by lung transplant include bone marrow suppression, herpes viral infections, liver cirrhosis, hypogammaglobulinemia, frailty, and cancer risk. This review aims to dissect the molecular mechanisms of immune aging and describe their clinical manifestations in the context of lung transplantation. While these mechanisms are more likely to manifest in the context of lung transplantation, this mechanism-based approach to clinical syndromes of immune aging has broad relevance to geriatric medicine.

Border-associated macrophages in the central nervous system

Tissue-resident macrophages play an important role in the local maintenance of homeostasis and immune surveillance. In the central nervous system (CNS), brain macrophages are anatomically divided into parenchymal microglia and non-parenchymal border-associated macrophages (BAMs). Among these immune cell populations, microglia have been well-studied for their roles in normal brain development, neurodegeneration, and brain cancers. BAMs, mostly located in the choroid plexus, meningeal and perivascular spaces, are now gaining increased attention due to advancements in multi-omics technologies and genetic methodologies. Research on BAMs over the past decade has focused on their ontogeny, immunophenotypes, involvement in various CNS diseases, and potential as therapeutic targets. Unlike microglia, BAMs display mixed origins and distinct self-renewal capacity. BAMs are believed to regulate neuroimmune responses associated with brain barriers and contribute to immune-mediated neuropathology. Notably, BAMs have been observed to function in diverse cerebral pathologies, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, ischemic stroke, and gliomas. The elucidation of the heterogeneity and diverse functions of BAMs during homeostasis and neuroinflammation is mesmerizing, since it may shed light on the precision medicine that emphasizes deep insights into programming cues in the unique brain immune microenvironment. In this review, we delve into the latest findings on BAMs, covering aspects like their origins, self-renewal capacity, adaptability, and implications in different brain disorders.

Lipid droplets, autophagy, and ageing: A cell-specific tale

Lipid droplets are the essential organelle for storing lipids in a cell. Within the variety of the human body, different cells store, utilize and release lipids in different ways, depending on their intrinsic function. However, these differences are not well characterized and, especially in the context of ageing, represent a key factor for cardiometabolic diseases. Whole body lipid homeostasis is a central interest in the field of cardiometabolic diseases. In this review we characterize lipid droplets and their utilization via autophagy and describe their diverse fate in three cells types central in cardiometabolic dysfunctions: adipocytes, hepatocytes, and macrophages.

Exploring the causal role of gut microbiota in giant cell arteritis: a Mendelian randomization analysis with mediator insights

Background

Giant Cell Arteritis (GCA) is a complex autoimmune condition. With growing interest in the role of gut microbiota in autoimmune diseases, this research aimed to explore the potential causal relationship between gut microbiota and GCA, and the mediating effects of specific intermediaries.

Methods

Using a bidirectional two-sample Mendelian randomization (MR) design, we investigated associations between 191 microbial taxa and GCA. A two-step MR technique discerned the significant mediators on this relationship, followed by Multivariable MR analyses to quantify the direct influence of gut microbiota on GCA and mediation effect proportion, adjusting for these mediators.

Results

Nine taxa displayed significant associations with GCA. Among them, families like Bacteroidales and Clostridiaceae1 had Odds Ratios (OR) of 1.48 (p=0.043) and 0.52 (p=5.51e-3), respectively. Genera like Clostridium sensu stricto1 and Desulfovibrio showed ORs of 0.48 (p=5.39e-4) and 1.48 (p=0.037), respectively. Mediation analyses identified 25 hydroxyvitamin D level (mediation effect of 19.95%), CD14+ CD16- monocyte counts (mediation effect of 27.40%), and CD4+ T cell counts (mediation effect of 28.51%) as significant intermediaries.

Conclusion

Our findings provide invaluable insights into the complex interplay between specific gut microbiota taxa and GCA. By highlighting the central role of gut microbiota in influencing GCA risk and long-term recurrence, and their interactions with vital immune mediators, this research paves the way for potential therapeutic interventions in GCA management.

Inflammaging and fatty acid oxidation in monocytes and macrophages

Fatty acid oxidation (FAO), primarily known as β-oxidation, plays a crucial role in breaking down fatty acids within mitochondria and peroxisomes to produce cellular energy and preventing metabolic dysfunction. Myeloid cells, including macrophages, microglia, and monocytes, rely on FAO to perform essential cellular functions and uphold tissue homeostasis. As individuals age, these cells show signs of inflammaging, a condition that includes a chronic onset of low-grade inflammation and a decline in metabolic function. These lead to changes in fatty acid metabolism and a decline in FAO pathways. Recent studies have shed light on metabolic shifts occurring in macrophages and monocytes during aging, correlating with an altered tissue environment and the onset of inflammaging. This review aims to provide insights into the connection of inflammatory pathways and altered FAO in macrophages and monocytes from older organisms. We describe a model in which there is an extended activation of receptor for advanced glycation end products, nuclear factor-κB (NF-κB) and the nod-like receptor family pyrin domain containing 3 inflammasome within macrophages and monocytes. This leads to an increased level of glycolysis, and also promotes pro-inflammatory cytokine production and signaling. As a result, FAO-related enzymes such as 5' AMP-activated protein kinase and peroxisome proliferator-activated receptor-α are reduced, adding to the escalation of inflammation, accumulation of lipids, and heightened cellular stress. We examine the existing body of literature focused on changes in FAO signaling within macrophages and monocytes and their contribution to the process of inflammaging.

Cell-type specific impact of metformin on monocyte epigenetic age reversal in virally suppressed older people living with HIV

The anti-diabetic drug metformin may promote healthy aging. However, few clinical trials of metformin assessing biomarkers of aging have been completed. In this communication, we retrospectively examined the effect of metformin on epigenetic age using principal component (PC)-based epigenetic clocks, mitotic clocks, and pace of aging in peripheral monocytes and CD8+ T cells from participants in two clinical trials of virologically-suppressed people living with HIV (PLWH) with normal glucose receiving metformin. In a small 24-week clinical trial that randomized participants to receive either adjunctive metformin or observation, we observed significantly decreased PCPhenoAge and PCGrimAge estimates of monocytes from only participants in the metformin arm by a mean decrease of 3.53 and 1.84 years from baseline to Week 24. In contrast, we observed no significant differences in all PC clocks for participants in the observation arm over 24 weeks. Notably, our analysis of epigenetic mitotic clocks revealed significant increases for monocytes in the metformin arm when comparing baseline to Week 24, suggesting an impact of metformin on myeloid cell kinetics. Analysis of a single-arm clinical trial of adjunctive metformin in eight PLWH revealed no significant differences across all epigenetic clocks assessed in CD8+ T cells at 4- and 8-week time points. Our results suggest cell-type-specific myeloid effects of metformin captured by PC-based epigenetic clock biomarkers. Larger clinical studies of metformin are needed to validate these observations and this report highlights the need for further inclusion of PLWH in geroscience trials evaluating the effect of metformin on increasing healthspan and lifespan.

Improving Blood Monocyte Energy Metabolism Enhances Its Ability to Phagocytose Amyloid-β and Prevents Alzheimer's Disease-Type Pathology and Cognitive Deficits

Deficiencies in the clearance of peripheral amyloid β (Aβ) play a crucial role in the progression of Alzheimer's disease (AD). Previous studies have shown that the ability of blood monocytes to phagocytose Aβ is decreased in AD. However, the exact mechanism of Aβ clearance dysfunction in AD monocytes remains unclear. In the present study, we found that blood monocytes in AD mice exhibited decreases in energy metabolism, which was accompanied by cellular senescence, a senescence-associated secretory phenotype, and dysfunctional phagocytosis of Aβ. Improving energy metabolism rejuvenated monocytes and enhanced their ability to phagocytose Aβ in vivo and in vitro. Moreover, enhancing blood monocyte Aβ phagocytosis by improving energy metabolism alleviated brain Aβ deposition and neuroinflammation and eventually improved cognitive function in AD mice. This study reveals a new mechanism of impaired Aβ phagocytosis in monocytes and provides evidence that restoring their energy metabolism may be a novel therapeutic strategy for AD.

Resolvin D2-G-Protein Coupled Receptor 18 Enhances Bone Marrow Function and Limits Steatosis and Hepatic Collagen Accumulation in Aging

Aging is associated with nonresolving inflammation and tissue dysfunction. Resolvin D2 (RvD2) is a proresolving ligand that acts through the G-protein-coupled receptor called GPR18. Unbiased RNA sequencing revealed increased Gpr18 expression in macrophages from old mice, and in livers from elderly humans, which was associated with increased steatosis and fibrosis in middle-aged (MA) and old mice. MA mice that lacked GPR18 on myeloid cells had exacerbated steatosis and hepatic fibrosis, which was associated with a decline in Mac2+ macrophages. Treatment of MA mice with RvD2 reduced steatosis and decreased hepatic fibrosis, correlating with increased Mac2+ macrophages, increased monocyte-derived macrophages, and elevated numbers of monocytes in the liver, blood, and bone marrow. RvD2 acted directly on the bone marrow to increase monocyte-macrophage progenitors. A transplantation assay further demonstrated that bone marrow from old mice facilitated hepatic collagen accumulation in young mice. Transient RvD2 treatment to mice transplanted with bone marrow from old mice prevented hepatic collagen accumulation. Together, this study demonstrates that RvD2-GPR18 signaling controls steatosis and fibrosis and provides a mechanistic-based therapy for promoting liver repair in aging.

Single-cell profiling reveals age-associated immunity in atherosclerosis

AIMS

Aging is a dominant driver of atherosclerosis and induces a series of immunological alterations, called immunosenescence. Given the demographic shift towards elderly, elucidating the unknown impact of aging on the immunological landscape in atherosclerosis is highly relevant. While the young Western diet-fed Ldlr-deficient (Ldlr-/-) mouse is a widely used model to study atherosclerosis, it does not reflect the gradual plaque progression in the context of an aging immune system as occurs in humans.

METHODS AND RESULTS

Here, we show that aging promotes advanced atherosclerosis in chow diet-fed Ldlr-/- mice, with increased incidence of calcification and cholesterol crystals. We observed systemic immunosenescence, including myeloid skewing and T-cells with more extreme effector phenotypes. Using a combination of single-cell RNA-sequencing and flow cytometry on aortic leucocytes of young vs. aged Ldlr-/- mice, we show age-related shifts in expression of genes involved in atherogenic processes, such as cellular activation and cytokine production. We identified age-associated cells with pro-inflammatory features, including GzmK+CD8+ T-cells and previously in atherosclerosis undefined CD11b+CD11c+T-bet+ age-associated B-cells (ABCs). ABCs of Ldlr-/- mice showed high expression of genes involved in plasma cell differentiation, co-stimulation, and antigen presentation. In vitro studies supported that ABCs are highly potent antigen-presenting cells. In cardiovascular disease patients, we confirmed the presence of these age-associated T- and B-cells in atherosclerotic plaques and blood.

CONCLUSIONS

Collectively, we are the first to provide comprehensive profiling of aged immunity in atherosclerotic mice and reveal the emergence of age-associated T- and B-cells in the atherosclerotic aorta. Further research into age-associated immunity may contribute to novel diagnostic and therapeutic tools to combat cardiovascular disease.

Efferocytosis: a double-edged sword in microbial immunity

Efferocytosis is characterized as the rapid and efficient process by which dying or dead cells are removed. This type of clearance is initiated via "find-me" signals, and then, carries on by "eat-me" and "don't-eat-me" ones. Efferocytosis has a critical role to play in tissue homeostasis and innate immunity. However, some evidence suggests it as a double-edged sword in microbial immunity. In other words, some pathogens have degraded efferocytosis by employing efferocytic mechanisms to bypass innate immune detection and promote infection, despite the function of this process for the control and clearance of pathogens. In this review, the efferocytosis mechanisms from the recognition of dying cells to phagocytic engulfment are initially presented, and then, its diverse roles in inflammation and immunity are highlighted. In this case, much focus is also laid on some bacterial, viral, and parasitic infections caused by Mycobacterium tuberculosis (M. tb), Mycobacterium marinum (M. marinum), Listeria monocytogenes (L. monocytogenes), Chlamydia pneumoniae (CP), Klebsiella pneumoniae (KP), Influenza A virus (IAV), human immunodeficiency virus (HIV), and Leishmania, respectively.

Baseline immune states (BIS) associated with vaccine responsiveness and factors that shape the BIS

Vaccines are among the greatest inventions in medicine, leading to the elimination or control of numerous diseases, including smallpox, polio, measles, rubella, and, most recently, COVID-19. Yet, the effectiveness of vaccines varies among individuals. In fact, while some recipients mount a robust response to vaccination that protects them from the disease, others fail to respond. Multiple clinical and epidemiological factors contribute to this heterogeneity in responsiveness. Systems immunology studies fueled by advances in single-cell biology have been instrumental in uncovering pre-vaccination immune cell types and genomic features (i.e., the baseline immune state, BIS) that have been associated with vaccine responsiveness. Here, we review clinical factors that shape the BIS, and the characteristics of the BIS associated with responsiveness to frequently studied vaccines (i.e., influenza, COVID-19, bacterial pneumonia, malaria). Finally, we discuss potential strategies to enhance vaccine responsiveness in high-risk groups, focusing specifically on older adults.

Brain macrophage development, diversity and dysregulation in health and disease

Brain macrophages include microglia in the parenchyma, border-associated macrophages in the meningeal-choroid plexus-perivascular space, and monocyte-derived macrophages that infiltrate the brain under various disease conditions. The vast heterogeneity of these cells has been elucidated over the last decade using revolutionary multiomics technologies. As such, we can now start to define these various macrophage populations according to their ontogeny and their diverse functional programs during brain development, homeostasis and disease pathogenesis. In this review, we first outline the critical roles played by brain macrophages during development and healthy aging. We then discuss how brain macrophages might undergo reprogramming and contribute to neurodegenerative disorders, autoimmune diseases, and glioma. Finally, we speculate about the most recent and ongoing discoveries that are prompting translational attempts to leverage brain macrophages as prognostic markers or therapeutic targets for diseases that affect the brain.

The multifaceted role of macrophages in homeostatic and injured skeletal muscle

Skeletal muscle is essential for body physical activity, energy metabolism, and temperature maintenance. It has excellent capabilities to maintain homeostasis and to regenerate after injury, which indispensably relies on muscle stem cells, satellite cells (MuSCs). The quiescence, activation, and differentiation of MuSCs are tightly regulated in homeostatic and regenerating muscles. Among the important regulators are intramuscular macrophages, which are functionally heterogeneous with different subtypes present in a spatiotemporal manner to regulate the balance of different MuSC statuses. During chronic injury and aging, intramuscular macrophages often undergo aberrant activation, which in turn disrupts muscle homeostasis and regenerative repair. Growing evidence suggests that the aberrant activation is mainly triggered by altered muscle microenvironment. The trained immunity that affects myeloid progenitors during hematopoiesis may also contribute. Aged immune system may contribute, in part, to the aging-related sarcopenia and compromised skeletal muscle injury repair. As macrophages are actively involved in the progression of many muscle diseases, manipulating their functional activation has become a promising therapeutic approach, which requires comprehensive knowledge of the cellular and molecular mechanisms underlying the diverse activation. To this end, we discuss here the current knowledge of multifaceted role of macrophages in skeletal muscle homeostasis, injury, and repair.

Non-Genomic Hallmarks of Aging-The Review

Aging is a natural, gradual, and inevitable process associated with a series of changes at the molecular, cellular, and tissue levels that can lead to an increased risk of many diseases, including cancer. The most significant changes at the genomic level (DNA damage, telomere shortening, epigenetic changes) and non-genomic changes are referred to as hallmarks of aging. The hallmarks of aging and cancer are intertwined. Many studies have focused on genomic hallmarks, but non-genomic hallmarks are also important and may additionally cause genomic damage and increase the expression of genomic hallmarks. Understanding the non-genomic hallmarks of aging and cancer, and how they are intertwined, may lead to the development of approaches that could influence these hallmarks and thus function not only to slow aging but also to prevent cancer. In this review, we focus on non-genomic changes. We discuss cell senescence, disruption of proteostasis, deregualation of nutrient sensing, dysregulation of immune system function, intercellular communication, mitochondrial dysfunction, stem cell exhaustion and dysbiosis.

Decoding the immune landscape following hip fracture in elderly patients: unveiling temporal dynamics through single-cell RNA sequencing

BACKGROUND

Hip fractures in the elderly have significant consequences, stemming from the initial trauma and subsequent surgeries. Hidden blood loss and stress due to concealed injury sites could impact the whole osteoimmune microenvironment. This study employs scRNA-seq technique to map immune profiles in elderly hip fracture patients from post-trauma to the recovery period, investigating the dynamic changes of immune inflammation regulation subgroups.

METHODS

We collected peripheral blood samples from four elderly hip fracture patients (two males and two females, all > 75 years of age) at three different time points (24 h post-trauma, 24 h post-operation, and day 7 post-operation) and applied scRNA-seq technique to analyze the cellular heterogeneity and identify differentially expressed genes in peripheral blood individual immune cells from elderly hip fracture patients.

RESULTS

In this study, we analyzed the composition and gene expression profiles of peripheral blood mononuclear cells (PBMCs) from elderly hip fracture patients by scRNA-seq and further identified new CD14 monocyte subpopulations based on marker genes and transcriptional profiles. Distinct gene expression changes were observed in various cell subpopulations at different time points. C-Mono2 monocyte mitochondria-related genes were up-regulated and interferon-related and chemokine-related genes were down-regulated within 24 h post-operation. Further analysis of gene expression profiles at day 7 post-operation showed that C-Mono2 monocytes showed downregulation of inflammation-related genes and osteoblast differentiation-related genes. However, the expression of these genes in cytotoxic T cells, Treg cells, and B cell subsets exhibited a contrasting trend. GZMK+CD8+ cytotoxic T cells showed downregulation of chemokine-related genes, and Treg cells showed upregulation of genes related to the JAK/STAT signaling pathway. Furthermore, we examined interactions among diverse immune cell subsets, pinpointing specific ligand-receptor pairs. These findings imply cross-talk and communication between various cell types in the post-traumatic immune response.

CONCLUSIONS

Our study elucidates the notable alterations in immune cell subpopulations during different stages of hip fracture in elderly patients, both in terms of proportions and differential gene expressions. These changes provide significant clinical implications for tissue repair, infection prevention, and fracture healing in clinic.

Bifurcation analysis of a tuberculosis progression model for drug target identification

Tuberculosis (TB) is a major cause of morbidity and mortality worldwide. The emergence and rapid spread of drug-resistant M. tuberculosis strains urge us to develop novel treatments. Experimental trials are constrained by laboratory capacity, insufficient funds, low number of laboratory animals and obsolete technology. Systems-level approaches to quantitatively study TB can overcome these limitations. Previously, we proposed a mathematical model describing the key regulatory mechanisms underlying the pathological progression of TB. Here, we systematically explore the effect of parameter variations on disease outcome. We find five bifurcation parameters that steer the clinical outcome of TB: number of bacteria phagocytosed per macrophage, macrophages death, macrophage killing by bacteria, macrophage recruitment, and phagocytosis of bacteria. The corresponding bifurcation diagrams show all-or-nothing dose-response curves with parameter regions mapping onto bacterial clearance, persistent infection, or history-dependent clearance or infection. Importantly, the pathogenic stage strongly affects the sensitivity of the host to these parameter variations. We identify parameter values corresponding to a latent-infection model of TB, where disease progression occurs significantly slower than in progressive TB. Two-dimensional bifurcation analyses uncovered synergistic parameter pairs that could act as efficient compound therapeutic approaches. Through bifurcation analysis, we reveal how modulation of specific regulatory mechanisms could steer the clinical outcome of TB.

Risk factors and novel predictive model for metastatic cutaneous squamous cell carcinoma: a population-based analysis

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin malignancies. Patients with metastatic cSCC (mcSCC) tended to have unfavorable prognosis. However, there is no available models to evaluate the survival outcomes for these patients. This study retrospectively collected mcSCC cases identified from The Surveillance, Epidemiology, and End Results (SEER) database from 2000 to 2018. All patients were randomly divided into the training and validation cohorts. The independent factors which predicted the cancer-specific survival (CSS) were identified by Cox proportional hazard regression analysis, and were used to build nomogram. he discrimination ability of nomograms was evaluated using the concordance index (C-index). The receiver operating characteristic (ROC) curve and the corresponding area under the curve (AUC) at 1, 3, and 5 years were calculated to estimate the predictive accuracy. The performance of this nomogram was evaluated by the calibration curves. The decision curve analyses (DCAs) were conducted to assess the clinical usefulness of the models. Based on the novel nomograms, all patients were classified into low- and high-risk groups. Kaplan-Meier curves were plotted to compare the survival outcomes of two groups. All analyses were conducted by R software (Version 4.1.3). A total of 916 patients were included. Age, marital status, location of the primary sites, number of metastases, T stage, N stage, surgical resection of the primary sites, radiotherapy of the primary sites, and chemotherapy were significantly associated with CSS. A nomogram predicting CSS was built based on these parameters. C-index and ROC curves of nomogram showed promising discriminating and predicting ability for CSS. Survival analysis showed that patients in the low-risk group had significant superior CSS time than those in the high-risk group (median CSS time: 15.0 vs. 5.0 months, p < 0.001). In conclusion, we developed and validated a novel nomogram predicting the CSS in metastatic cSCC patients. This nomogram could be used to assess the prognosis of metastatic cSCC patients, and help clinicians evaluating optimal treatment options for individual patient.

Immune Remodeling during Aging and the Clinical Significance of Immunonutrition in Healthy Aging

Aging is associated with changes in the immune system and the gut microbiota. Immunosenescence may lead to a low-grade, sterile chronic inflammation in a multifactorial and dynamic way, which plays a critical role in most age-related diseases. Age-related changes in the gut microbiota also shape the immune and inflammatory responses. Nutrition is a determinant of immune function and of the gut microbiota. Immunonutrion has been regarded as a new strategy for disease prevention and management, including many age-related diseases. However, the understanding of the cause-effect relationship is required to be more certain about the role of immunonutrition in supporting the immune homeostasis and its clinical relevance in elderly individuals. Herein, we review the remarkable quantitative and qualitative changes during aging that contribute to immunosenescence, inflammaging and microbial dysbiosis, and the effects on late-life health conditions. Furthermore, we discuss the clinical significance of immunonutrition in the treatment of age-related diseases by systematically reviewing its modulation of the immune system and the gut microbiota to clarify the effect of immunonutrition-based interventions on the healthy aging.

Identification of ROCK1 as a novel biomarker for postmenopausal osteoporosis and pan-cancer analysis

BACKGROUND

Postmenopausal osteoporosis (PMOP) is a prevalent bone disorder with significant global impact. The elevated risk of osteoporotic fracture in elderly women poses a substantial burden on individuals and society. Unfortunately, the current lack of dependable diagnostic markers and precise therapeutic targets for PMOP remains a major challenge.

METHODS

PMOP-related datasets GSE7429, GSE56814, GSE56815, and GSE147287, were downloaded from the GEO database. The DEGs were identified by "limma" packages. WGCNA and Machine Learning were used to choose key module genes highly related to PMOP. GSEA, DO, GO, and KEGG enrichment analysis was performed on all DEGs and the selected key hub genes. The PPI network was constructed through the GeneMANIA database. ROC curves and AUC values validated the diagnostic values of the hub genes in both training and validation datasets. xCell immune infiltration and single-cell analysis identified the hub genes' function on immune reaction in PMOP. Pan-cancer analysis revealed the role of the hub genes in cancers.

RESULTS

A total of 1278 DEGs were identified between PMOP patients and the healthy controls. The purple module and cyan module were selected as the key modules and 112 common genes were selected after combining the DEGs and module genes. Five Machine Learning algorithms screened three hub genes (KCNJ2, HIPK1, and ROCK1), and a PPI network was constructed for the hub genes. ROC curves validate the diagnostic values of ROCK1 in both the training (AUC = 0.73) and validation datasets of PMOP (AUC = 0.81). GSEA was performed for the low-ROCK1 patients, and the top enriched field included protein binding and immune reaction. DCs and NKT cells were highly expressed in PMOP. Pan-cancer analysis showed a correlation between low ROCK1 expression and SKCM as well as renal tumors (KIRP, KICH, and KIRC).

CONCLUSIONS

ROCK1 was significantly associated with the pathogenesis and immune infiltration of PMOP, and influenced cancer development, progression, and prognosis, which provided a potential therapy target for PMOP and tumors. However, further laboratory and clinical evidence is required before the clinical application of ROCK1 as a therapeutic target.

Immune aging - A mechanism in autoimmune disease

Evidence is emerging that the process of immune aging is a mechanism leading to autoimmunity. Over lifetime, the immune system adapts to profound changes in hematopoiesis and lymphogenesis, and progressively restructures in face of an ever-expanding exposome. Older adults fail to generate adequate immune responses against microbial infections and tumors, but accumulate aged T cells, B cells and myeloid cells. Age-associated B cells are highly efficient in autoantibody production. T-cell aging promotes the accrual of end-differentiated effector T cells with potent cytotoxic and pro-inflammatory abilities and myeloid cell aging supports a low grade, sterile and chronic inflammatory state (inflammaging). In pre-disposed individuals, immune aging can lead to frank autoimmune disease, manifesting with chronic inflammation and irreversible tissue damage. Emerging data support the concept that autoimmunity results from aging-induced failure of fundamental cellular processes in immune effector cells: genomic instability, loss of mitochondrial fitness, failing proteostasis, dwindling lysosomal degradation and inefficient autophagy. Here, we have reviewed the evidence that malfunctional mitochondria, disabled lysosomes and stressed endoplasmic reticula induce pathogenic T cells and macrophages that drive two autoimmune diseases, rheumatoid arthritis (RA) and giant cell arteritis (GCA). Recognizing immune aging as a risk factor for autoimmunity will open new avenues of immunomodulatory therapy, including the repair of malfunctioning mitochondria and lysosomes.

Immunology of human fibrosis

Fibrosis, defined by the excess deposition of structural and matricellular proteins in the extracellular space, underlies tissue dysfunction in multiple chronic diseases. Approved antifibrotics have proven modest in efficacy, and the immune compartment remains, for the most part, an untapped therapeutic opportunity. Recent single-cell analyses have interrogated human fibrotic tissues, including immune cells. These studies have revealed a conserved profile of scar-associated macrophages, which localize to the fibrotic niche and interact with mesenchymal cells that produce pathological extracellular matrix. Here we review recent advances in the understanding of the fibrotic microenvironment in human diseases, with a focus on immune cell profiles and functional immune-stromal interactions. We also discuss the key role of the immune system in mediating fibrosis regression and highlight avenues for future study to elucidate potential approaches to targeting inflammatory cells in fibrotic disorders.

Modified Rice Bran Arabinoxylan by Lentinus edodes Mycelial Enzyme as an Immunoceutical for Health and Aging-A Comprehensive Literature Review

Rice bran arabinoxylan compound (RBAC) is derived from defatted rice bran enzymatically treated with Lentinus edodes mycelium. This review explores biologically active compounds and mechanisms of action that support RBAC as an immunomodulating nutraceutical in generally healthy and/or aging individuals. Thirty-seven (n = 37) primary research articles fulfilled the selection criteria for review. Most research is based on Biobran MGN-3, which consists of complex heteropolysaccharides with arabinoxylan as its primary structure while also containing galactan and glucan. RBAC was found to invoke immunological activities through direct absorption via the digestive tract and interaction with immune cells at the Peyer's patches. RBAC was shown to promote innate defence by upregulating macrophage phagocytosis and enhancing natural killer cell activity while lowering oxidative stress. Through induction of dendritic cell maturation, RBAC also augments adaptive immunity by promoting T and B lymphocyte proliferation. RBAC acts as an immunomodulator by inhibiting mast cell degranulation during allergic reactions, attenuating inflammation, and downregulating angiogenesis by modulating cytokines and growth factors. RBAC has been shown to be a safe and effective nutraceutical for improving immune health, notably in aging individuals with reduced immune function. Human clinical trials with geriatric participants have demonstrated RBAC to have prophylactic benefits against viral infection and may improve their quality of life. Further research should explore RBAC's bioavailability, pharmacodynamics, and pharmacokinetics of the complex heteropolysaccharides within. Translational research to assess RBAC as a nutraceutical for the aging population is still required, particularly in human studies with larger sample sizes and cohort studies with long follow-up periods.

Aging Aggravates Periodontal Inflammatory Responses and Alveolar Bone Resorption by Porphyromonas gingivalis Infection

Periodontitis is a chronic inflammatory disease driven by periodontal pathogens such as Porphyromonas gingivalis (P. gingivalis), and its prevalence increases with age. However, little is known about the effect of immunosenescence on inflammatory response to P. gingivalis infection. In the present study, 16S rDNA sequencing analysis showed the relative abundance of P. gingivalis was significantly higher in periodontitis patients than healthy group, but there was no difference between the young (20 to 40 years old) and old (65 to 86 years old) periodontitis groups. Furthermore, the cytotoxic effect of P. gingivalis was greater on old THP-1 macrophages and on bone mar-row-derived cells (BMDMs) from old mice, and levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-12 were higher in old than in young THP-1 macrophages. Furthermore, the activations of inflammasome components for IL-1β production by P. gingivalis infection were greater in old THP-1 macrophages. Finally, bone loss was significantly greater in P. gingivalis-infected aged mice than in young mice. These findings indicate that aging aggravates P. gingivalis-induced inflammatory cytokine secretion and inflammasome activation. The study enhances understanding of the relationship between periodontal immunosenescence and inflammatory response in the elderly.

Exploration for the reference interval of C-reactive protein in the Chinese longevity people over 90 years of age

BACKGROUND

Older individuals tend to develop chronic inflammation. As a commonly used nonspecific inflammatory marker, C-reactive protein (CRP) can predict metabolic syndrome, cardiovascular diseases, etc. However, little is known about CRP levels in longevity people.

OBJECTIVES

Investigate the distribution and correlates of CRP and provide a reference for the establishment of normal interval values in Chinese longevity people over 90 years of age.

METHODS

We performed a correlation analysis to evaluate the correlation between CRP levels and longevity based on the basic demographic characteristics, anthropometric measurements and blood data of 4,418 participants in the 2015 China Health and Retirement Longitudinal Study and 636 participants in an ongoing longitudinal study of natural longevity people in Guangxi. On this basis, the CRP reference interval for longevity was explored.

RESULTS

The CRP concentration was significantly different among the three age groups, with a median of 3.80 mg/L for those older than 90 years, which was significantly higher than that for those aged 45-64 years (median 1.20 mg/L, p < 0.001) and 65-89 years (median 1.30 mg/L, p < 0.001). Body mass index, waist circumference, the waist-to-height ratio, systolic blood pressure, diastolic blood pressure, and fasting and postprandial blood glucose, triglyceride, total cholesterol and low-density lipoprotein cholesterol levels were positively correlated with CRP levels, while fasting high-density lipoprotein cholesterol was negatively correlated with CRP levels. The CRP reference interval (RI) value in longevity people was 0.25-9.22 mg/L.

CONCLUSION

The concentrations of CRP increased with advancing age, and the CRP reference interval was different between older and younger adults.

Multi-View Learning to Unravel the Different Levels Underlying Hepatitis B Vaccine Response

The immune system acts as an intricate apparatus that is dedicated to mounting a defense and ensures host survival from microbial threats. To engage this faceted immune response and provide protection against infectious diseases, vaccinations are a critical tool to be developed. However, vaccine responses are governed by levels that, when interrogated, separately only explain a fraction of the immune reaction. To address this knowledge gap, we conducted a feasibility study to determine if multi-view modeling could aid in gaining actionable insights on response markers shared across populations, capture the immune system's diversity, and disentangle confounders. We thus sought to assess this multi-view modeling capacity on the responsiveness to the Hepatitis B virus (HBV) vaccination. Seroconversion to vaccine-induced antibodies against the HBV surface antigen (anti-HBs) in early converters (n = 21; <2 months) and late converters (n = 9; <6 months) and was defined based on the anti-HBs titers (>10IU/L). The multi-view data encompassed bulk RNA-seq, CD4+ T-cell parameters (including T-cell receptor data), flow cytometry data, and clinical metadata (including age and gender). The modeling included testing single-view and multi-view joint dimensionality reductions. Multi-view joint dimensionality reduction outperformed single-view methods in terms of the area under the curve and balanced accuracy, confirming the increase in predictive power to be gained. The interpretation of these findings showed that age, gender, inflammation-related gene sets, and pre-existing vaccine-specific T-cells could be associated with vaccination responsiveness. This multi-view dimensionality reduction approach complements clinical seroconversion and all single modalities. Importantly, this modeling could identify what features could predict HBV vaccine response. This methodology could be extended to other vaccination trials to identify the key features regulating responsiveness.

Defective efferocytosis by aged macrophages promotes STING signaling mediated inflammatory liver injury

Aged livers have shown aggravated liver ischemia and reperfusion (IR) injury. Timely efferocytosis of apoptotic cells is a key mechanism for avoiding excessive inflammation and tissue injury. Here, we investigated the alteration of efferocytosis by aged macrophages and its role in regulating macrophage STING (stimulator of interferon genes) signaling and liver IR injury. Aged and young mice were subjected to liver partial IR model. Liver injury and inflammation were measured. Efferocytosis by aged macrophages and the underlying regulatory mechanism were analyzed as well. Aged macrophages exhibited impaired efferocytosis with decreased MerTK (c-mer proto-oncogene tyrosine kinase) activation, which was reversed by treatment of the MerTK CRISPR activation plasmid. Increased MerTK cleavage by ADAM17 (a disintegrin and metalloproteinase 17) due to enhanced ROS (reactive oxygen species) levels contributed to defective efferocytosis by aged macrophages. MerTK activation by suppressing ADAM17 or ROS improved aged macrophage efferocytosis, leading to reduced inflammatory liver injury. Moreover, increased apoptotic hepatocytes, DNA accumulation, and macrophage STING activation were observed in aged ischemic livers. Improvement in efferocytosis by aged macrophages via MerTK activation suppressed STING activation and inflammatory liver injury. Our study demonstrates that aging suppresses MerTK- mediated macrophage efferocytosis to promote macrophage STING activation and inflammatory liver IR injury, suggesting a new mechanism and potential therapy to promote inflammation resolution and efferocytosis in aged livers.

Impact of aging on treatment considerations for multiple sclerosis patients

With a rapidly aging global population and improvement of outcomes with newer multiple sclerosis (MS)-specific disease-modifying therapies (DMTs), the epidemiology of MS has shifted to an older than previously described population, with a peak prevalence of the disease seen in the 55-65 years age group. Changes in the pathophysiology of MS appear to be age-dependent. Several studies have identified a consistent phase of disability worsening around the fifth decade of life. The latter appears to be independent of prior disease duration and inflammatory activity and concomitant to pathological changes from acute focal active demyelination to chronic smoldering plaques, slow-expanding lesions, and compartmentalized inflammation within the central nervous system (CNS). On the other hand, decreased CNS tissue reserve and poorer remyelinating capacity with aging lead to loss of relapse recovery potential. Aging with MS may imply longer exposure to DMTs, although treatment efficacy in patients >55 years has not been evaluated in pivotal randomized controlled trials and appears to decrease with age. Older individuals are more prone to adverse effects of DMTs, an important aspect of treatment individualization. Aging with MS also implies a higher global burden of comorbid illnesses that contribute to overall impairments and represent a crucial confounder in interpreting clinical worsening. Discontinuation of DMTs after age 55, when no evidence of clinical or radiological activity is detected, is currently under the spotlight. In this review, we will discuss the impact of aging on MS pathobiology, the effect of comorbidities and other confounders on clinical worsening, and focus on current therapeutic considerations in this age group.

Counteracting Immunosenescence-Which Therapeutic Strategies Are Promising?

Aging attenuates the overall responsiveness of the immune system to eradicate pathogens. The increased production of pro-inflammatory cytokines by innate immune cells under basal conditions, termed inflammaging, contributes to impaired innate immune responsiveness towards pathogen-mediated stimulation and limits antigen-presenting activity. Adaptive immune responses are attenuated as well due to lowered numbers of naïve lymphocytes and their impaired responsiveness towards antigen-specific stimulation. Additionally, the numbers of immunoregulatory cell types, comprising regulatory T cells and myeloid-derived suppressor cells, that inhibit the activity of innate and adaptive immune cells are elevated. This review aims to summarize our knowledge on the cellular and molecular causes of immunosenescence while also taking into account senescence effects that constitute immune evasion mechanisms in the case of chronic viral infections and cancer. For tumor therapy numerous nanoformulated drugs have been developed to overcome poor solubility of compounds and to enable cell-directed delivery in order to restore immune functions, e.g., by addressing dysregulated signaling pathways. Further, nanovaccines which efficiently address antigen-presenting cells to mount sustained anti-tumor immune responses have been clinically evaluated. Further, senolytics that selectively deplete senescent cells are being tested in a number of clinical trials. Here we discuss the potential use of such drugs to improve anti-aging therapy.

AP-1 is a regulatory transcription factor of inflammaging in the murine kidney and liver

Aging is characterized by chronic low-grade inflammation in multiple tissues, also termed "inflammaging", which represents a significant risk factor for many aging-related chronic diseases. However, the mechanisms and regulatory networks underlying inflammaging across different tissues have not yet been fully elucidated. Here, we profiled the transcriptomes and epigenomes of the kidney and liver from young and aged mice and found that activation of the inflammatory response is a conserved signature in both tissues. Moreover, we revealed links between transcriptome changes and chromatin dynamics through integrative analysis and identified AP-1 and ETS family transcription factors (TFs) as potential regulators of inflammaging. Further in situ validation showed that c-JUN (a member of the AP-1 family) was mainly activated in aged renal and hepatic cells, while increased SPI1 (a member of the ETS family) was mostly induced by elevated infiltration of macrophages, indicating that these TFs have different mechanisms in inflammaging. Functional data demonstrated that genetic knockdown of Fos, a major member of the AP-1 family, significantly attenuated the inflammatory response in aged kidneys and livers. Taken together, our results revealed conserved signatures and regulatory TFs of inflammaging in the kidney and liver, providing novel targets for the development of anti-aging interventions.

Older and wiser: The benefits to neonates of aged neutrophils

Neonates are relatively protected from non-neonatal pathogens by unclear mechanisms. In this issue of Immunity, Bee et al.¹ show that resistance to Streptococcus pneumoniae in neonatal mice is mediated by dampened neutrophil efferocytosis, accumulation of aged neutrophils, and enhanced CD11b-dependent bacterial opsonophagocytosis.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

Impact of aging on immunity in the context of COVID-19, HIV, and tuberculosis

Knowledge of aging biology needs to be expanded due to the continuously growing number of elderly people worldwide. Aging induces changes that affect all systems of the body. The risk of cardiovascular disease and cancer increases with age. In particular, the age-induced adaptation of the immune system causes a greater susceptibility to infections and contributes to the inability to control pathogen growth and immune-mediated tissue damage. Since the impact of aging on immune function, is still to be fully elucidated, this review addresses some of the recent understanding of age-related changes affecting key components of immunity. The emphasis is on immunosenescence and inflammaging that are impacted by common infectious diseases that are characterized by a high mortality, and includes COVID-19, HIV and tuberculosis.

The making of the oral microbiome in Agta hunter-gatherers

Ecological and genetic factors have influenced the composition of the human microbiome during our evolutionary history. We analysed the oral microbiota of the Agta, a hunter-gatherer population where some members have adopted an agricultural diet. We show that age is the strongest factor modulating the microbiome, probably through immunosenescence since we identified an increase in the number of species classified as pathogens with age. We also characterised biological and cultural processes generating sexual dimorphism in the oral microbiome. A small subset of oral bacteria is influenced by the host genome, linking host collagen genes to bacterial biofilm formation. Our data also suggest that shifting from a fish/meat diet to a rice-rich diet transforms their microbiome, mirroring the Neolithic transition. All of these factors have implications in the epidemiology of oral diseases. Thus, the human oral microbiome is multifactorial and shaped by various ecological and social factors that modify the oral environment.

Therapeutic effects of MSCs, genetically modified MSCs, and NFĸB-inhibitor on chronic inflammatory osteolysis in aged mice

The number of total joint replacements is increasing, especially in elderly patients, and so too are implant-related complications such as prosthesis loosening. Wear particles from the prosthesis induce a chronic inflammatory reaction and subsequent osteolysis, leading to the need for revision surgery. This study investigated the therapeutic effect of NF-ĸB decoy oligodeoxynucleotides (ODN), mesenchymal stem cells (MSCs), and genetically-modified NF-ĸB sensing interleukin-4 over-secreting MSCs (IL4-MSCs) on chronic inflammation in aged mice. The model was generated by continuous infusion of contaminated polyethylene particles into the intramedullary space of the distal femur of aged mice (15-17 months old) for 6 weeks. Local delivery of ODN showed increased bone mineral density (BMD), decreased osteoclast-like cells, increased alkaline phosphatase (ALP)-positive area, and increased M2/M1 macrophage ratio. Local injection of MSCs and IL4-MSCs significantly decreased osteoclast-like cells and increased the M2/M1 ratio, with a greater trend for IL4-MSCs than MSCs. MSCs significantly increased ALP-positive area and BMD values compared with the control. The IL4-MSCs demonstrated higher values for both ALP-positive area and BMD. These findings demonstrated the therapeutic effects of ODN, MSCs, and IL4-MSCs on chronic inflammatory osteolysis in aged mice. The two MSC-based therapies were more effective than ODN in increasing the M2/M1 macrophage ratio, reducing bone resorption, and increasing bone formation. Specifically, MSCs were more effective in increasing bone formation, and IL4-MSCs were more effective in mitigating inflammation. This study suggests potential therapeutic strategies for treating wear particle-associated inflammatory osteolysis after arthroplasty in the elderly.