Aging Induces an Nlrp3 Inflammasome-Dependent Expansion of Adipose B Cells That Impairs Metabolic Homeostasis

Adipose tissue in older individuals: a contributing factor to sarcopenia

Sarcopenia is a geriatric syndrome characterized by a functional decline in muscle. The prevalence of sarcopenia increases with natural aging, becoming a serious health problem among elderly individuals. Therefore, understanding the pathology of sarcopenia is critical for inhibiting age-related alterations and promoting health and longevity in elderly individuals. The development of sarcopenia may be influenced by interactions between visceral and subcutaneous adipose tissue and skeletal muscle, particularly under conditions of chronic low-grade inflammation and metabolic dysfunction. This hypothesis is supported by the following observations: (i) accumulation of senescent cells in both adipose tissue and skeletal muscle with age; (ii) gut dysbiosis, characterized by an imbalance in gut microbial communities as the main trigger for inflammation, sarcopenia, and aged adipose tissue; and (iii) microbial dysbiosis, which could impact the onset or progression of a senescent state. Moreover, adipose tissue acts as an endocrine organ, releasing molecules that participate in intricate communication networks between organs. Our discussion focuses on novel adipokines and their role in regulating adipose tissue and muscle, particularly those influenced by aging and obesity, emphasizing their contributions to disease development. On the basis of these findings, we propose that age-related adipose tissue and sarcopenia are disorders characterized by chronic inflammation and metabolic dysregulation. Finally, we explore new potential therapeutic strategies involving specialized proresolving mediator (SPM) G protein-coupled receptor (GPCR) agonists, non-SPM GPCR agonists, transient receptor potential (TRP) channels, antidiabetic drugs in conjunction with probiotics and prebiotics, and compounds designed to target senescent cells and mitigate their pro-inflammatory activity.

Protocol to examine murine visceral adipose tissue immune cells using fluorescence-based flow cytometry

Adipose tissue immune cells are heterogeneous and dynamic, alter metabolism, and drive immune responses. Here, we present a protocol for assessment and characterization of murine adipose tissue immune cells using fluorescence-based flow cytometry and sorting into pure populations. We describe steps for isolation of the stromovascular fraction, antibody staining, and data collection by flow cytometry. We also discuss common issues and troubleshooting steps. For complete details on the use and execution of this protocol, please refer to Carey et al.1.

Hypothalamic SLC7A14 accounts for aging-reduced lipolysis in white adipose tissue of male mice

The central nervous system has been implicated in the age-induced reduction in adipose tissue lipolysis. However, the underlying mechanisms remain unclear. Here, we show the expression of SLC7A14 is reduced in proopiomelanocortin (POMC) neurons of aged mice. Overexpression of SLC7A14 in POMC neurons alleviates the aging-reduced lipolysis, whereas SLC7A14 deletion mimics the age-induced lipolysis impairment. Metabolomics analysis reveals that POMC SLC7A14 increased taurochenodeoxycholic acid (TCDCA) content, which mediates the SLC7A14 knockout- or age-induced WAT lipolysis impairment. Furthermore, SLC7A14-increased TCDCA content is dependent on intestinal apical sodium-dependent bile acid transporter (ASBT), which is regulated by intestinal sympathetic afferent nerves. Finally, SLC7A14 regulates the intestinal sympathetic afferent nerves by inhibiting mTORC1 signaling through inhibiting TSC1 phosphorylation. Collectively, our study suggests the function for central SLC7A14 and an upstream mechanism for the mTORC1 signaling pathway. Moreover, our data provides insights into the brain-gut-adipose tissue crosstalk in age-induced lipolysis impairment.

Adipose tissue senescence: Biological changes, hallmarks and therapeutic approaches

Adipose tissue (AT), the largest energy storage reservoir and endocrine organ, plays a crucial role in regulating systemic energy metabolism. As one of the most vulnerable tissues during aging, the plasticity of AT is impaired. With age, AT undergoes redistribution, characterized by expansion of visceral adipose tissue (VAT) and reduction of peripheral subcutaneous adipose tissue (SAT). Additionally, age-related changes in AT include reduced adipogenesis of white adipocytes, decreased proliferation and differentiation capacity of mesenchymal stromal/stem cells (MSCs), diminished thermogenic capacity in brown/beige adipocytes, and dysregulation of immune cells. Specific and sensitive hallmarks enable the monitoring and evaluation of the biological changes associated with aging. In this study, we have innovatively proposed seven characteristic hallmarks of AT senescence, including telomere attrition, epigenetic alterations, genomic instability, mitochondrial dysfunction, disabled macroautophagy, cellular senescence, and chronic inflammation, which are intricately interconnected and mutually regulated. Finally, we discussed anti-aging strategies targeting AT, offering insights into mitigating or delaying metabolic disturbances caused by AT senescence.

A nutrigeroscience approach: Dietary macronutrients and cellular senescence

Cellular senescence, a process in which a cell exits the cell cycle in response to stressors, is one of the hallmarks of aging. Senescence and the senescence-associated secretory phenotype (SASP)-a heterogeneous set of secreted factors that disrupt tissue homeostasis and promote the accumulation of senescent cells-reprogram metabolism and can lead to metabolic dysfunction. Dietary interventions have long been studied as methods to combat age-associated metabolic dysfunction, promote health, and increase lifespan. A growing body of literature suggests that senescence is responsive to diet, both to calories and specific dietary macronutrients, and that the metabolic benefits of dietary interventions may arise in part through reducing senescence. Here, we review what is currently known about dietary macronutrients' effect on senescence and the SASP, the nutrient-responsive molecular mechanisms that may mediate these effects, and the potential for these findings to inform the development of a nutrigeroscience approach to healthy aging.

Tertiary lymphoid structures in diseases: immune mechanisms and therapeutic advances

Tertiary lymphoid structures (TLSs) are defined as lymphoid aggregates formed in non-hematopoietic organs under pathological conditions. Similar to secondary lymphoid organs (SLOs), the formation of TLSs relies on the interaction between lymphoid tissue inducer (LTi) cells and lymphoid tissue organizer (LTo) cells, involving multiple cytokines. Heterogeneity is a distinguishing feature of TLSs, which may lead to differences in their functions. Growing evidence suggests that TLSs are associated with various diseases, such as cancers, autoimmune diseases, transplant rejection, chronic inflammation, infection, and even ageing. However, the detailed mechanisms behind these clinical associations are not yet fully understood. The mechanisms by which TLS maturation and localization affect immune function are also unclear. Therefore, it is necessary to enhance the understanding of TLS development and function at the cellular and molecular level, which may allow us to utilize them to improve the immune microenvironment. In this review, we delve into the composition, formation mechanism, associations with diseases, and potential therapeutic applications of TLSs. Furthermore, we discuss the therapeutic implications of TLSs, such as their role as markers of therapeutic response and prognosis. Finally, we summarize various methods for detecting and targeting TLSs. Overall, we provide a comprehensive understanding of TLSs and aim to develop more effective therapeutic strategies.

Adiposity, immunity, and inflammation: interrelationships in health and disease: a report from 24th Annual Harvard Nutrition Obesity Symposium, June 2023

The rapidly evolving field of immunometabolism explores how changes in local immune environments may affect key metabolic and cellular processes, including that of adipose tissue. Importantly, these changes may contribute to low-grade systemic inflammation. In turn, chronic low-grade inflammation affecting adipose tissue may exacerbate the outcome of metabolic diseases. Novel advances in our understanding of immunometabolic processes may critically lead to interventions to reduce disease severity and progression. An important example in this regard relates to obesity, which has a multifaceted effect on immunity, activating the proinflammatory pathways such as the inflammasome and disrupting cellular homeostasis. This multifaceted effect of obesity can be investigated through study of downstream conditions using cellular and systemic investigative techniques. To further explore this field, the National Institutes of Health P30 Nutrition Obesity Research Center at Harvard, in partnership with Harvard Medical School, assembled experts to present at its 24th Annual Symposium entitled "Adiposity, Immunity, and Inflammation: Interrelationships in Health and Disease" on 7 June, 2023. This manuscript seeks to synthesize and present key findings from the symposium, highlighting new research and novel disease-specific advances in the field. Better understanding the interaction between metabolism and immunity offers promising preventative and treatment therapies for obesity-related immunometabolic diseases.

Fat-associated lymphoid clusters: Supporting visceral adipose tissue B cell function in immunity and metabolism

It is now widely understood that visceral adipose tissue (VAT) is a highly active and dynamic organ, with many functions beyond lipid accumulation and storage. In this review, we discuss the immunological role of this tissue, underpinned by the presence of fat-associated lymphoid clusters (FALCs). FALC's distinctive structure and stromal cell composition support a very different immune cell mix to that found in classical secondary lymphoid organs, which underlies their unique functions of filtration, surveillance, innate-like immune responses, and adaptive immunity within the serous cavities. FALCs are important B cell hubs providing B1 cell-mediated frontline protection against infection and supporting B2 cell-adaptative immune responses. Beyond these beneficial immune responses orchestrated by FALCs, immune cells within VAT play important homeostatic role. Dysregulation of immune cells during obesity and aging leads to chronic pathological "metabolic inflammation", which contributes to the development of cardiometabolic diseases. Here, we examine the emerging and complex functions of B cells in VAT homeostasis and the metabolic complications of obesity, highlighting the potential role that FALCs play and emphasize the areas where further research is needed.

Aging and homeostasis of the hypodermis in the age-related deterioration of skin function

Adipose tissues in the hypodermis, the crucial stem cell reservoir in the skin and the endocrine organ for the maintenance of skin homeostasis undergo significant changes during skin aging. Dermal white adipose tissue (dWAT) has recently been recognized as an important organ for both non-metabolic and metabolic health in skin regeneration and rejuvenation. Defective differentiation, adipogenesis, improper adipocytokine production, and immunological dissonance dysfunction in dWAT lead to age-associated clinical changes. Here, we review age-related alterations in dWAT across levels, emphasizing the mechanisms underlying the regulation of aging. We also discuss the pathogenic changes involved in age-related fat dysfunction and the unfavorable consequences of accelerated skin aging, such as chronic inflammaging, immunosenescence, delayed wound healing, and fibrosis. Research has shown that adipose aging is an early initiation event and a potential target for extending longevity. We believe that adipose tissues play an essential role in aging and form a potential therapeutic target for the treatment of age-related skin diseases. Further research is needed to improve our understanding of this phenomenon.

Sex-dependent effects of carbohydrate source and quantity on caspase-1 activity in the mouse central nervous system

BACKGROUND

Mounting evidence links glucose intolerance and diabetes as aspects of metabolic dysregulation that are associated with an increased risk of developing dementia. Inflammation and inflammasome activation have emerged as a potential link between these disparate pathologies. As diet is a key factor in both the development of metabolic disorders and inflammation, we hypothesize that long term changes in dietary factors can influence nervous system function by regulating inflammasome activity and that this phenotype would be sex-dependent, as sex hormones are known to regulate metabolism and immune processes.

METHODS

5-week-old male and female transgenic mice expressing a caspase-1 bioluminescent reporter underwent cranial window surgeries and were fed control (65% complex carbohydrates, 15% fat), high glycemic index (65% carbohydrates from sucrose, 15% fat), or ketogenic (1% complex carbohydrates, 79% fat) diet from 6 to 26 weeks of age. Glucose regulation was assessed with a glucose tolerance test following a 4-h morning fast. Bioluminescence in the brain was quantified using IVIS in vivo imaging. Blood cytokine levels were measured using cytokine bead array. 16S ribosomal RNA gene amplicon sequencing of mouse feces was performed to assess alterations in the gut microbiome. Behavior associated with these dietary changes was also evaluated.

RESULTS

The ketogenic diet caused weight gain and glucose intolerance in both male and female mice. In male mice, the high glycemic diet led to increased caspase-1 biosensor activation over the course of the study, while in females the ketogenic diet drove an increase in biosensor activation compared to their respective controls. These changes correlated with an increase in inflammatory cytokines present in the serum of test mice and the emergence of anxiety-like behavior. The microbiome composition differed significantly between diets; however no significant link between diet, glucose tolerance, or caspase-1 signal was established.

CONCLUSIONS

Our findings suggest that diet composition, specifically the source and quantity of carbohydrates, has sex-specific effects on inflammasome activation in the central nervous system and behavior. This phenotype manifested as increased anxiety in male mice, and future studies are needed to determine if this phenotype is linked to alterations in microbiome composition.

MicroRNA-7 deficiency ameliorates d-galactose-induced aging in mice by regulating senescence of Kupffer cells

Aging is intricately linked to immune system dysfunction. Recent studies have highlighted the biological function of microRNA-7 (miR-7) as a novel regulator of immune cell function and related diseases. However, the potential role of miR-7 in aging remains unexplored. Here, we investigated the contribution of miR-7 to d-gal-induced aging in mice, focusing on its regulation of senescent Kupffer cells. Our findings revealed that miR-7 deficiency significantly ameliorated the aging process, characterized by enhanced CD4+ T-cell activation. However, the adoptive transfer of miR-7-deficient CD4+T cells failed to improve the age-related phenotype. Further analysis showed that miR-7 deficiency significantly reduced IL-1β production in liver tissue, and inhibiting IL-1β in vivo slowed down the aging process in mice. Notably, IL-1β is mainly produced by senescent Kupffer cells in the liver tissue of aging mice, and miR-7 expression was significantly up-regulated in these cells. Mechanistically, KLF4, a target of miR-7, was down-regulated in senescent Kupffer cells in aging mouse model. Furthermore, miR-7 deficiency also modulated the NF-κB activation and IL-1β production in senescent Kupffer cells through KLF4. In conclusion, our findings unveil the role of miR-7 in d-gal-induced aging in mice, highlighting its regulation of KLF4/NF-κB/IL-1β pathways in senescent Kupffer cells. This research may enhance our understanding of miRNA-based aging immune cells and offer new avenues for new intervention strategies in aging process.

Mechanisms of Vascular Inflammation and Potential Therapeutic Targets: A Position Paper From the ESH Working Group on Small Arteries

Inflammatory responses in small vessels play an important role in the development of cardiovascular diseases, including hypertension, stroke, and small vessel disease. This involves various complex molecular processes including oxidative stress, inflammasome activation, immune-mediated responses, and protein misfolding, which together contribute to microvascular damage. In addition, epigenetic factors, including DNA methylation, histone modifications, and microRNAs influence vascular inflammation and injury. These phenomena may be acquired during the aging process or due to environmental factors. Activation of proinflammatory signaling pathways and molecular events induce low-grade and chronic inflammation with consequent cardiovascular damage. Identifying mechanism-specific targets might provide opportunities in the development of novel therapeutic approaches. Monoclonal antibodies targeting inflammatory cytokines and epigenetic drugs, show promise in reducing microvascular inflammation and associated cardiovascular diseases. In this article, we provide a comprehensive discussion of the complex mechanisms underlying microvascular inflammation and offer insights into innovative therapeutic strategies that may ameliorate vascular injury in cardiovascular disease.

Metabolism-inflammasome crosstalk shapes innate and adaptive immunity

Inflammasomes are a central component of innate immunity and play a vital role in regulating innate immune response. Activation of inflammasomes is also indispensable for adaptive immunity, modulating the development and response of adaptive immunity. Recently, increasing studies have shown that metabolic alterations and adaptations strongly influence and regulate the differentiation and function of the immune system. In this review, we will take a holistic view of how inflammasomes bridge innate and adaptive (especially T cell) immunity and how inflammasomes crosstalk with metabolic signals during the immune responses. And, special attention will be paid to the metabolic control of inflammasome-mediated interactions between innate and adaptive immunity in disease. Understanding the metabolic regulatory functions of inflammasomes would provide new insights into future research directions in this area and may help to identify potential targets for inflammasome-associated diseases and broaden therapeutic avenues.

Association between sedentary behavior and dynapenic abdominal obesity among older adults from low- and middle-income countries

BACKGROUND

Sedentary behavior, or time spent sitting, may increase risk for dynapenic abdominal obesity (DAO), but there are currently no studies on this topic.

AIMS

Therefore, we investigated the association between sedentary behaviour and DAO in a nationally representative sample of older adults from six low- and middle-income countries.

METHODS

Cross-sectional data from the Study on Global AGEing and Adult Health were analysed. Dynapenia was defined as handgrip strength < 26 kg for men and < 16 kg for women. Abdominal obesity was defined as waist circumference of > 88 cm (> 80 cm for Asian countries) for women and > 102 cm (> 90 cm) for men. DAO was defined as having both dynapenia and abdominal obesity. Self-reported sedentary behavior was categorized as ≥ 8 h/day (high sedentary behaviour) or < 8 h/day. Multivariable multinomial logistic regression was conducted.

RESULTS

Data on 20,198 adults aged ≥ 60 years were analyzed [mean (SD) age 69.3 (13.1) years; 54.1% females]. In the overall sample, ≥ 8 h of sedentary behavior per day (vs. <8 h) was significantly associated with 1.52 (95%CI = 1.11-2.07) times higher odds for DAO (vs. no dynapenia and no abdominal obesity), and this was particularly pronounced among males (OR = 2.27; 95%CI = 1.42-3.62). Highly sedentary behavior was not significantly associated with dynapenia alone or abdominal obesity alone.

DISCUSSION

High sedentary behaviour may increase risk for DAO among older adults.

CONCLUSIONS

Interventions to reduce sedentary behaviour may also lead to reduction of DAO and its adverse health outcomes, especially among males, pending future longitudinal research.

Posttransplant Tertiary Lymphoid Organs

Tertiary lymphoid organs (TLOs), also known as tertiary or ectopic lymphoid structures or tissues, are accumulations of lymphoid cells in sites other than canonical lymphoid organs, that arise through lymphoid neogenesis during chronic inflammation in autoimmunity, microbial infection, cancer, aging, and transplantation, the focus of this review. Lymph nodes and TLOs are compared regarding their cellular composition, organization, vascular components, and migratory signal regulation. These characteristics of posttransplant TLOs (PT-TLOs) are described with individual examples in a wide range of organs including heart, kidney, trachea, lung, artery, skin, leg, hand, and face, in many species including human, mouse, rat, and monkey. The requirements for induction and maintenance of TLOs include sustained exposure to autoantigens, alloantigens, tumor antigens, ischemic reperfusion, nephrotoxic agents, and aging. Several staging schemes have been put forth regarding their function in organ rejection. PT-TLOs most often are associated with organ rejection, but in some cases contribute to tolerance. The role of PT-TLOs in cancer is considered in the case of immunosuppression. Furthermore, TLOs can be associated with development of lymphomas. Challenges for PT-TLO research are considered regarding staging, imaging, and opportunities for their therapeutic manipulation to inhibit rejection and encourage tolerance.

Adipose tissue as a linchpin of organismal ageing

Ageing is a conserved biological process, modulated by intrinsic and extrinsic factors, that leads to changes in life expectancy. In humans, ageing is characterized by greatly increased prevalence of cardiometabolic disease, type 2 diabetes and disorders associated with impaired immune surveillance. Adipose tissue displays species-conserved, temporal changes with ageing, including redistribution from peripheral to central depots, loss of thermogenic capacity and expansion within the bone marrow. Adipose tissue is localized to discrete depots, and also diffusely distributed within multiple organs and tissues in direct proximity to specialized cells. Thus, through their potent endocrine properties, adipocytes are capable of modulating tissue and organ function throughout the body. In addition to adipocytes, multipotent progenitor/stem cells in adipose tissue play a crucial role in maintenance and repair of tissues throughout the lifetime. Adipose tissue may therefore be a central driver for organismal ageing and age-associated diseases. Here we review the features of adipose tissue during ageing, and discuss potential mechanisms by which these changes affect whole-body metabolism, immunity and longevity. We also explore the potential of adipose tissue-targeted therapies to ameliorate age-associated disease burdens.

Spatiotemporal proteomic profiling of cellular responses to NLRP3 agonists

Nucleotide-binding domain and leucine-rich repeat pyrin-domain containing protein 3 (NLRP3) is an innate immune sensor that forms an inflammasome in response to various cellular stressors. Gain-of-function mutations in NLRP3 cause autoinflammatory diseases and NLRP3 signalling itself exacerbates the pathogenesis of many other human diseases. Despite considerable therapeutic interest, the primary drivers of NLRP3 activation remain controversial due to the diverse array of signals that are integrated through NLRP3. Here, we mapped subcellular proteome changes to lysosomes, mitochondrion, EEA1-positive endosomes, and Golgi caused by the NLRP3 inflammasome agonists nigericin and CL097. We identified several common disruptions to retrograde trafficking pathways, including COPI and Shiga toxin-related transport, in line with recent studies. We further characterized mouse NLRP3 trafficking throughout its activation using temporal proximity proteomics, which supports a recent model of NLRP3 recruitment to endosomes during inflammasome activation. Collectively, these findings provide additional granularity to our understanding of the molecular events driving NLRP3 activation and serve as a valuable resource for cell biological research. We have made our proteomics data accessible through an open-access Shiny browser to facilitate future research within the community, available at: https://harperlab.connect.hms.harvard.edu/inflame/. We will display anonymous peer review for this manuscript on pubpub.org (https://harperlab.pubpub.org/pub/nlrp3/) rather than a traditional journal. Moreover, we invite community feedback on the pubpub version of this manuscript, and we will address criticisms accordingly.

Adaptive immunity and atherosclerosis: aging at its crossroads

Adaptive immunity plays a profound role in atherosclerosis pathogenesis by regulating antigen-specific responses, inflammatory signaling and antibody production. However, as we age, our immune system undergoes a gradual functional decline, a phenomenon termed "immunosenescence". This decline is characterized by a reduction in proliferative naïve B- and T cells, decreased B- and T cell receptor repertoire and a pro-inflammatory senescence associated secretory profile. Furthermore, aging affects germinal center responses and deteriorates secondary lymphoid organ function and structure, leading to impaired T-B cell dynamics and increased autoantibody production. In this review, we will dissect the impact of aging on adaptive immunity and the role played by age-associated B- and T cells in atherosclerosis pathogenesis, emphasizing the need for interventions that target age-related immune dysfunction to reduce cardiovascular disease risk.

IgG is an aging factor that drives adipose tissue fibrosis and metabolic decline

Aging is underpinned by pronounced metabolic decline; however, the drivers remain obscure. Here, we report that IgG accumulates during aging, particularly in white adipose tissue (WAT), to impair adipose tissue function and metabolic health. Caloric restriction (CR) decreases IgG accumulation in WAT, whereas replenishing IgG counteracts CR's metabolic benefits. IgG activates macrophages via Ras signaling and consequently induces fibrosis in WAT through the TGF-β/SMAD pathway. Consistently, B cell null mice are protected from aging-associated WAT fibrosis, inflammation, and insulin resistance, unless exposed to IgG. Conditional ablation of the IgG recycling receptor, neonatal Fc receptor (FcRn), in macrophages prevents IgG accumulation in aging, resulting in prolonged healthspan and lifespan. Further, targeting FcRn by antisense oligonucleotide restores WAT integrity and metabolic health in aged mice. These findings pinpoint IgG as a hidden culprit in aging and enlighten a novel strategy to rejuvenate metabolic health.

Age-associated accumulation of B cells promotes macrophage inflammation and inhibits lipolysis in adipose tissue during sepsis

Non-canonical lipolysis induced by inflammatory cytokines or Toll-like receptor ligands is required for the regulation of inflammation during endotoxemia and sepsis. Canonical lipolysis induced by catecholamines declines during aging due to factors including an expansion of lymphocytes, pro-inflammatory macrophage polarization, and an increase in chronic low-grade inflammation; however, the extent to which the non-canonical pathway of lipolysis is active and impacted by immune cells during aging remains unclear. Therefore, we aimed to define the extent to which immune cells from old mice influence non-canonical lipolysis during sepsis. We identified age-associated impairments of non-canonical lipolysis and an accumulation of dysfunctional B1 B cells in the visceral white adipose tissue (vWAT) of old mice. Lifelong deficiency of B cells results in restored non-canonical lipolysis and reductions in pro-inflammatory macrophage populations. Our study suggests that targeting the B cell-macrophage signaling axis may resolve metabolic dysfunction in aged vWAT and attenuate septic severity in older individuals.

Cancer cachexia: biomarkers and the influence of age

Cancer cachexia (Ccx) is a complex metabolic condition characterized by pronounced muscle and fat wasting, systemic inflammation, weakness and fatigue. Up to 30% of cancer patients succumb directly to Ccx, yet therapies that effectively address this perturbed metabolic state are rare. In recent decades, several characteristics of Ccx have been established in mice and humans, of which we here highlight adipose tissue dysfunction, muscle wasting and systemic inflammation, as they are directly linked to biomarker discovery. To counteract cachexia pathogenesis as early as possible and mitigate its detrimental impact on anti-cancer treatments, identification and validation of clinically endorsed biomarkers assume paramount importance. Ageing was recently shown to affect both the validity of Ccx biomarkers and Ccx development, but the underlying mechanisms are still unknown. Thus, unravelling the intricate interplay between ageing and Ccx can help to counteract Ccx pathogenesis and tailor diagnostic and treatment strategies to individual needs.

The role of NLRP3 inflammasome in aging and age-related diseases

The gradual aging of the global population has led to a surge in age-related diseases, which seriously threaten human health. Researchers are dedicated to understanding and coping with the complexities of aging, constantly uncovering the substances and mechanism related to aging like chronic low-grade inflammation. The NOD-like receptor protein 3 (NLRP3), a key regulator of the innate immune response, recognizes molecular patterns associated with pathogens and injury, initiating an intrinsic inflammatory immune response. Dysfunctional NLRP3 is linked to the onset of related diseases, particularly in the context of aging. Therefore, a profound comprehension of the regulatory mechanisms of the NLRP3 inflammasome in aging-related diseases holds the potential to enhance treatment strategies for these conditions. In this article, we review the significance of the NLRP3 inflammasome in the initiation and progression of diverse aging-related diseases. Furthermore, we explore preventive and therapeutic strategies for aging and related diseases by manipulating the NLRP3 inflammasome, along with its upstream and downstream mechanisms.

Aging adipose tissue, insulin resistance, and type 2 diabetes

With the increase of population aging, the prevalence of type 2 diabetes (T2D) is also rising. Aging affects the tissues and organs of the whole body, which is the result of various physiological and pathological processes. Adipose tissue has a high degree of plasticity and changes with aging. Aging changes the distribution of adipose tissue, affects adipogenesis, browning characteristics, inflammatory status and adipokine secretion, and increases lipotoxicity. These age-dependent changes in adipose tissue are an important cause of insulin resistance and T2D. Understanding adipose tissue changes can help promote healthy aging process. This review summarizes changes in adipose tissue ascribable to aging, with a focus on the role of aging adipose tissue in insulin resistance and T2D.

NLRP3 Deficiency in Nonimmune Cells Averts Obesity-Induced Fatty Liver Disease

Obesity predisposes to metabolic dysfunction-associated fatty liver disease (MAFLD), cardiovascular disease, and type 2 diabetes. Accumulating evidence suggests a complex role of NLR family pyrin domain containing 3 (NLRP3) inflammasome function in multiple manifestations of the metabolic syndrome, with contradictory results. Its broad expression and pleiotropic functions during obesity led us to investigate the contribution of its expression in nonimmune versus immune cells to the development of obesity and MAFLD. Bone marrow chimerism was used to target NLRP3 deficiency to immune (ImmuneΔNlrp3) versus nonimmune (NonimmuneΔNlrp3) cells. Irradiated WT mice reconstituted with WT bone marrow served as controls. Mice were fed a 60% high-fat diet for 16 weeks. NonimmuneΔNlrp3 mice gained less weight and displayed reduced liver and epididymal white adipose tissue (epiWAT) mass. They also exhibited reduced adipocyte hypertrophy and increased epiWAT adipogenesis and lipolysis. Notable was the diminished hepatic steatosis in NonimmuneΔNlrp3 livers, which persisted even following equilibration of their body weight to that of the control. This was accompanied by a decline in liver triglycerides and in expression of transcriptional modules involved with lipid uptake, storage, and de novo lipogenesis. Thermogenic pathways in brown adipose tissue were comparable to control mice, but an elevation was observed in the genes encoding for lipid transporters and fatty acid oxidation. In contrast, deletion of NLRP3 in the immune cell compartment had limited effects on obesity and hepatic steatosis. Collectively, our results outline a prominent role for NLRP3 in nonimmune cells in facilitating MAFLD during constant energy surplus.

The anti-liver fibrosis effect of Tibetan medicine (Qiwei Tiexie capsule) is related to the inhibition of NLRP3 inflammasome activation in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Qiwei Tiexie capsule (QWTX) is an improved form of a classical prescription of Tibetan medicine-Qiwei Tiexie pill. It has been employed in the treatment of a variety of chronic liver disorders, including liver fibrosis. Uncertainty still exists regarding the mechanism of QWTX action in liver fibrosis.

AIM OF THE STUDY

Confirm the anti-liver fibrosis effect of QWTX and reveal its mechanism from the perspective of NOD-like receptor protein 3 (NLRP3) inflammasome activation.

MATERIALS AND METHODS

In vivo experiment: A rat model of carbon tetrachloride -induced liver fibrosis was constructed. All rats were randomly divided into six groups: a control group, a model group, a group receiving the positive drug (Biejia Ruangan tablet), and three groups receiving QWTX at high, medium, and low doses. The contents of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin (TBil) were detected in serum. Hematoxylin and eosin staining and Masson's staining were used to assess the histomorphological alteration of the liver. The levels of glutathione peroxidase, hydroxyproline, tumor necrosis factor alpha (TNF-α), and interleukin 1 beta (IL-1β) in the liver were determined using the corresponding detection kits. Real-time polymerase chain reaction, immunofluorescence, and western blotting were used to determine the expression levels of NLRP3, adaptor protein (ASC), caspase-1, and alpha-smooth muscle actin (α-SMA). In vitro experiment: Four groups of rat hepatic stellate cell line (HSC-T6) cells were created: the control group, the low-dose QWTX group (0.05 mg/mL), the medium-dose QWTX group (0.1 mg/mL), and the high-dose QWTX group (0.2 mg/mL). Cell viability was assessed using a cell counting kit, and the amounts of collagen type I (Col I) and IL-1β in the cell lysate were measured using an enzyme-linked immunosorbent assay kit. The mRNA and protein expression of NLRP3, ASC, caspase-1, and α-SMA were also estimated.

RESULTS

QWTX had an inhibitory effect on liver fibrosis and a negative effect on HSC activation, while it improved liver histopathological injury and abnormal liver function and increased hydroxyproline content and glutathione peroxidase activity in vivo. QWTX decreased the expression of α-SMA, NLRP3, caspase-1, ASC, and IL-1β both in vitro and in vivo.

CONCLUSIONS

Tibetan medicine QWTX had a significant anti-liver fibrosis effect that was related to the inhibition of NLRP3 inflammasome activation in vivo and in vitro.

Mechanisms of γδ T cell accumulation in visceral adipose tissue with aging

γδ T cells are resident in visceral adipose tissue (VAT) where they show an age-associated increase in numbers and contribute to local and systemic chronic inflammation. However, regulation of this population and mechanisms for the age-dependent accumulation are not known. In this study, we identified a progressive trend of γδ T cell accumulation in VAT over the lifespan in mice and explored physiological mechanisms contributing to accumulation. Using isochronic parabiotic pairs of wild-type (WT) and T cell receptor delta knockout (TCRδ KO) mice at young and old age, we confirmed that VAT γδ T cells are predominately a tissue-resident population which is sustained in aging. Migration of peripheral γδ T cells into VAT was observed at less than 10%, with a decreasing trend by aging, suggesting a minor contribution of recruitment to γδ T cell accumulation with aging. Since tissue-resident T cell numbers are tightly regulated by a balance between proliferation and programmed cell death, we further explored these processes. Using in vivo EdU incorporation and the proliferation marker Ki67, we found that the absolute number of proliferating γδ T cells in VAT is significantly higher in the aged compared to young and middle-aged mice, despite a decline in the proportion of proliferating to non-proliferating cells by age. Analysis of apoptosis via caspase 3/7 activation revealed that VAT γδ T cells show reduced apoptosis starting at middle age and continuing into old age. Further, induction of apoptosis using pharmacological inhibitors of Bcl2 family proteins revealed that VAT γδ T cells at middle age are uniquely protected from apoptosis via a mechanism independent of traditional anti-apoptotic Bcl2-family proteins. Collectively, these data indicate that protection from apoptosis at middle age increases survival of tissue-resident γδ T cells resulting in an increased number of proliferative cells from middle age onward, and leading to the age-associated accumulation of γδ T cells in VAT. These findings are important to better understand how adipose tissue dysfunction and related changes in the immune profile contribute to inflammaging among the elderly.

The NLRP3 molecule influences the therapeutic effects of mesenchymal stem cells through Glut1-mediated energy metabolic reprogramming

INTRODUCTION

Numerous studies demonstrated that NLRP3 has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Mesenchymal stem cells (MSCs) regulated the NLRP3 inflammasome, which has emerged as a novel therapeutic approach for treating IBD.

OBJECTIVES

The exact role of NLRP3 in regulating MSCs' function is unclear. Our study aimed to explore how NLRP3 affects the therapeutic effects of MSCs in colitis.

METHODS

We extracted MSCs from the bone marrow of C57BL/6 mice and Nlrp3 KO mice, and identified them using differentiation assays and flow cytometry. In vitro, Both WT MSCs and Nlrp3 KO MSCs were stimulated with inflammatory factor Lipopolysaccharide (LPS), and only WT MSCs were stimulated with varying concentrations of the NLRP3 inhibitor MCC950, then, quantified IL-10 levels in the supernatant. RNA-seq was performed to examine gene expression patterns and Seahorse was used to assess oxidative phosphorylation (OXPHOS) and glycolysis levels. Western blot was used to evaluate protein expression. In vivo, we treated DSS-induced colitis with either WT or Nlrp3 KO MSCs, monitoring weight, measuring colon length, and further evaluation. We also treated DSS-induced colitis with pretreated MSCs (BAY876, oe-Glut1, or oe-NLRP3), following the same experimental procedures as described above.

RESULTS

Our results demonstrate that Nlrp3 deletion did not affect MSC phenotypes, but rather promoted osteogenic differentiation. However, the absence of Nlrp3 reduced IL-10 production in MSCs in the presence of LPS, leading to impaired protection on DSS-induced colitis. Conversely, overexpression of NLRP3 promotes the production of IL-10, enhancing therapeutic effects. Further investigation revealed that Nlrp3 deficiency downregulated Glut1 expression and glycolysis activation in MSCs, resulting in decreased IL-10 production. Notably, overexpressing Glut1 in Nlrp3 KO MSCs restored their therapeutic effect that was previously dampened due to Nlrp3 deletion.

CONCLUSION

Our findings demonstrate that NLRP3 heightens the therapeutic effects of MSC treatment on DSS-induced colitis.

Sex differences in radiation research

PURPOSE

The Sex Differences in Radiation Research workshop addressed the role of sex as a confounder in radiation research and its implication in real-world radiological and nuclear applications.

METHODS

In April 2022, HHS-wide partners from the Radiation and Nuclear Countermeasures Program, the Office of Research on Women's Health National Institutes of Health Office of Women's Health, U.S. Food and Drug Administration, and the Radiological and Nuclear Countermeasures Branch at the Biomedical Advanced Research and Development Authority conducted a workshop to address the scientific implication and knowledge gaps in understanding sex in basic and translational research. The goals of this workshop were to examine sex differences in 1. Radiation animal models and understand how these may affect radiation medical countermeasure development; 2. Biodosimetry and/or biomarkers used to assess acute radiation syndrome, delayed effects of acute radiation exposure, and/or predict major organ morbidities; 3. medical research that lacks representation from both sexes. In addition, regulatory policies that influence inclusion of women in research, and the gaps that exist in drug development and device clearance were discussed. Finally, real-world sex differences in human health scenarios were also considered.

RESULTS

This report provides an overview of the two-day workshop, and open discussion among academic investigators, industry researchers, and U.S. government representatives.

CONCLUSIONS

This meeting highlighted that current study designs lack the power to determine statistical significance based on sex, and much is unknown about the underlying factors that contribute to these differences. Investigators should accommodate both sexes in all stages of research to ensure that the outcome is robust, reproducible, and accurate, and will benefit public health.

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.

Alveolar epithelial regeneration in the aging lung

Advancing age is the most important risk factor for the development of and mortality from acute and chronic lung diseases, including pneumonia, chronic obstructive pulmonary disease, and pulmonary fibrosis. This risk was manifest during the COVID-19 pandemic, when elderly people were disproportionately affected and died from SARS-CoV-2 pneumonia. However, the recent pandemic also provided lessons on lung resilience. An overwhelming majority of patients with SARS-CoV-2 pneumonia, even those with severe disease, recovered with near-complete restoration of lung architecture and function. These observations are inconsistent with historic views of the lung as a terminally differentiated organ incapable of regeneration. Here, we review emerging hypotheses that explain how the lung repairs itself after injury and why these mechanisms of lung repair fail in some individuals, particularly the elderly.

Vutiglabridin exerts anti-ageing effects in aged mice through alleviating age-related metabolic dysfunctions

BACKGROUND

Ageing alters the ECM, leading to mitochondrial dysfunction and oxidative stress, which triggers an inflammatory response that exacerbates with age. Age-related changes impact satellite cells, affecting muscle regeneration, and the balance of proteins. Furthermore, ageing causes a decline in NAD+ levels, and alterations in fat metabolism that impact our health. These various metabolic issues become intricately intertwined with ageing, leading to a variety of individual-level diseases and profoundly affecting individuals' healthspan. Therefore, we hypothesize that vutiglabridin capable of alleviating these metabolic abnormalities will be able to ameliorate many of the problems associated with ageing.

METHOD

The efficacy of vutiglabridin, which alleviates metabolic issues by enhancing mitochondrial function, was assessed in aged mice treated with vutiglabridin and compared to untreated elderly mice. On young mice, vutiglabridin-treated aged mice, and non-treated aged mice, the Senescence-associated beta-galactosidase staining and q-PCR for ageing marker genes were carried out. Bulk RNA-seq was carried out on GA muscle, eWAT, and liver from each group of mice to compare differences in gene expression in various gene pathways. Blood from each group of mice was used to compare and analyze the ageing lipid profile.

RESULTS

SA-β-gal staining of eWAT, liver, kidney, and spleen of ageing mice showed that vutiglabridin had anti-ageing effects compared to the control group, and q-PCR of ageing marker genes including Cdkn1a and Cdkn2a in each tissue showed that vutiglabridin reduced the ageing process. In aged mice treated with vutiglabridin, GA muscle showed improved homeostasis compared to controls, eWAT showed restored insulin sensitivity and prevented FALC-induced inflammation, and liver showed reduced inflammation levels due to prevented TLO formation, improved mitochondrial complex I assembly, resulting in reduced ROS formation. Furthermore, blood lipid analysis revealed that ageing-related lipid profile was relieved in ageing mice treated with vutiglabridin versus the control group.

CONCLUSION

Vutiglabridin slows metabolic ageing mechanisms such as decreased insulin sensitivity, increased inflammation, and altered NAD+ metabolism in adipose tissue in mice experiments, while also retaining muscle homeostasis, which is deteriorated with age. It also improves the lipid profile in the blood and restores mitochondrial function in the liver to reduce ROS generation.

Sterile inflammation and the NLRP3 inflammasome in cardiometabolic disease

Inflammation plays an important role in the pathophysiology of cardiometabolic diseases. Sterile inflammation, a non-infectious and damage-associated molecular pattern (DAMP)-induced innate response, is now well-established to be closely associated with development and progression of cardiometabolic diseases. The NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome is well-established as a major player in sterile inflammatory responses. It is a multimeric cytosolic protein complex which regulates the activation of caspase-1 and subsequently promotes cleavage and release of interleukin (IL)-1 family cytokines, which have a deleterious impact on the development of cardiometabolic diseases. Therefore, targeting NLRP3 itself or the downstream consequences of NLRP3 activation represent excellent potential therapeutic targets in inflammatory cardiometabolic diseases. Here, we review our current understanding of the role which NLRP3 inflammasome regulation plays in cardiometabolic diseases such as obesity, diabetes, non-alcoholic steatohepatitis (NASH), atherosclerosis, ischemic heart disease and cardiomyopathy. Finally, we highlight the potential of targeting NLPR3 or related signaling molecules as a therapeutic approach.

Immune Dysfunction from Radiation Exposure

The hematopoietic system is highly sensitive to ionizing radiation. Damage to the immune system may result in opportunistic infections and hemorrhage, which could lead to mortality. Inflammation triggered by tissue damage can also lead to additional local or widespread tissue damage. The immune system is responsible for tissue repair and restoration, which is made more challenging when it is in the process of self-recovery. Because of these challenges, the Radiation and Nuclear Countermeasures Program (RNCP) and the Basic Immunology Branch (BIB) under the Division of Allergy, Immunology, and Transplantation (DAIT) within the National Institute of Allergy and Infectious Diseases (NIAID), along with partners from the Biomedical Advanced Research and Development Authority (BARDA), and the Radiation Injury Treatment Network (RITN) sponsored a two-day meeting titled Immune Dysfunction from Radiation Exposure held on September 9-10, 2020. The intent was to discuss the manifestations and mechanisms of radiation-induced immune dysfunction in people and animals, identify knowledge gaps, and discuss possible treatments to restore immune function and enhance tissue repair after irradiation.

B Cells Promote T Cell Immunosenescence and Mammalian Aging Parameters

A dysregulated adaptive immune system is a key feature of aging, and is associated with age-related chronic diseases and mortality. Most notably, aging is linked to a loss in the diversity of the T cell repertoire and expansion of activated inflammatory age-related T cell subsets, though the main drivers of these processes are largely unknown. Here, we find that T cell aging is directly influenced by B cells. Using multiple models of B cell manipulation and single-cell omics, we find B cells to be a major cell type that is largely responsible for the age-related reduction of naive T cells, their associated differentiation towards pathogenic immunosenescent T cell subsets, and for the clonal restriction of their T cell receptor (TCR). Accordingly, we find that these pathogenic shifts can be therapeutically targeted via CD20 monoclonal antibody treatment. Mechanistically, we uncover a new role for insulin receptor signaling in influencing age-related B cell pathogenicity that in turn induces T cell dysfunction and a decline in healthspan parameters. These results establish B cells as a pivotal force contributing to age-associated adaptive immune dysfunction and healthspan outcomes, and suggest new modalities to manage aging and related multi-morbidity.

Stem-like CD4+ T cells in perivascular tertiary lymphoid structures sustain autoimmune vasculitis

Autoimmune vasculitis of the medium and large elastic arteries can cause blindness, stroke, aortic arch syndrome, and aortic aneurysm. The disease is often refractory to immunosuppressive therapy and progresses over decades as smoldering aortitis. How the granulomatous infiltrates in the vessel wall are maintained and how tissue-infiltrating T cells and macrophages are replenished are unknown. Single-cell and whole-tissue transcriptomic studies of immune cell populations in vasculitic arteries identified a CD4+ T cell population with stem cell-like features. CD4+ T cells supplying the tissue-infiltrating and tissue-damaging effector T cells survived in tertiary lymphoid structures around adventitial vasa vasora, expressed the transcription factor T cell factor 1 (TCF1), had high proliferative potential, and gave rise to two effector populations, Eomesodermin (EOMES)+ cytotoxic T cells and B cell lymphoma 6 (BCL6)+ T follicular helper-like cells. TCF1hiCD4+ T cells expressing the interleukin 7 receptor (IL-7R) sustained vasculitis in serial transplantation experiments. Thus, TCF1hiCD4+ T cells function as disease stem cells and promote chronicity and autonomy of autoimmune tissue inflammation. Remission-inducing therapies will require targeting stem-like CD4+ T cells instead of only effector T cells.

Impaired BCAA catabolism in adipose tissues promotes age-associated metabolic derangement

Adipose tissues are central in controlling metabolic homeostasis and failure in their preservation is associated with age-related metabolic disorders. The exact role of mature adipocytes in this phenomenon remains elusive. Here we describe the role of adipose branched-chain amino acid (BCAA) catabolism in this process. We found that adipocyte-specific Crtc2 knockout protected mice from age-associated metabolic decline. Multiomics analysis revealed that BCAA catabolism was impaired in aged visceral adipose tissues, leading to the activation of mechanistic target of rapamycin complex (mTORC1) signaling and the resultant cellular senescence, which was restored by Crtc2 knockout in adipocytes. Using single-cell RNA sequencing analysis, we found that age-associated decline in adipogenic potential of visceral adipose tissues was reinstated by Crtc2 knockout, via the reduction of BCAA-mTORC1 senescence-associated secretory phenotype axis. Collectively, we propose that perturbation of BCAA catabolism by CRTC2 is critical in instigating age-associated remodeling of adipose tissue and the resultant metabolic decline in vivo.

Integrated bioinformatic analysis and experimental validation for exploring the key molecular of brain inflammaging

Aims

Integrating bioinformatics and experimental validation to explore the mechanisms of inflammaging in the Brain.

Method

After dividing the GSE11882 dataset into aged and young groups, we identified co-expressed differentially expressed genes (DEGs) in different brain regions. Enrichment analysis revealed that the co-expressed DEGs were mainly associated with inflammatory responses. Subsequently, we identified 12 DEGs that were related to the inflammatory response and used the DGIdb website for drug prediction. By using both the least absolute shrinkage and selection operator (LASSO) and random forest (RF), four biomarkers were screened and an artificial neural network (ANN) was developed for diagnosis. Subsequently, the biomarkers were validated through animal studies. Then we utilized AgeAnno to investigate the roles of biomarkers at the single cell level. Next, a consensus clustering approach was used to classify the aging samples and perform differential analysis to identify inflammatory response-related genes. After conducting a weighted gene co-expression network analysis (WGCNA), we identified the genes that are correlated with both four brain regions and aging. Wayne diagrams were used to identify seven inflammaging-related genes in different brain regions. Finally, we performed immuno-infiltration analysis and identified macrophage module genes.

Key findings

Inflammaging may be a major mechanism of brain aging, and the regulation of macrophages by CX3CL1 may play a role in the development of inflammaging.

Significance

In summary, targeting CX3CL1 can potentially delay inflammaging and immunosenescence in the brain.

Mechanism of immune attack in the progression of obesity-related type 2 diabetes

Obesity and overweight are widespread issues in adults, children, and adolescents globally, and have caused a noticeable rise in obesity-related complications such as type 2 diabetes mellitus (T2DM). Chronic low-grade inflammation is an important promotor of the pathogenesis of obesity-related T2DM. This proinflammatory activation occurs in multiple organs and tissues. Immune cell-mediated systemic attack is considered to contribute strongly to impaired insulin secretion, insulin resistance, and other metabolic disorders. This review focused on highlighting recent advances and underlying mechanisms of immune cell infiltration and inflammatory responses in the gut, islet, and insulin-targeting organs (adipose tissue, liver, skeletal muscle) in obesity-related T2DM. There is current evidence that both the innate and adaptive immune systems contribute to the development of obesity and T2DM.

The Transcriptomic Landscape of Age-Induced Changes in Human Visceral Fat and the Predicted Omentum-Liver Connectome in Males

Aging causes alterations in body composition. Specifically, visceral fat mass increases with age and is associated with age-related diseases. The pathogenic potential of visceral fat accumulation has been associated with its anatomical location and metabolic activity. Visceral fat may control systemic metabolism by secreting molecules that act in distal tissues, mainly the liver, through the portal vein. Currently, little is known about age-related changes in visceral fat in humans. Aiming to identify molecular and cellular changes occurring with aging in the visceral fat of humans, we analyzed publicly available transcriptomic data of 355 omentum samples from the Genotype-Tissue Expression portal (GTEx) of 20-79-year-old males and females. We identified the functional enrichment of genes associated with aging, inferred age-related changes in visceral fat cellularity by deconvolution analysis, profiled the senescence-associated secretory phenotype of visceral adipose tissue, and predicted the connectivity of the age-induced visceral fat secretome with the liver. We demonstrate that age induces alterations in visceral fat cellularity, synchronous to changes in metabolic pathways and a shift toward a pro-inflammatory secretory phenotype. Furthermore, our approach identified candidates such as ADIPOQ-ADIPOR1/ADIPOR2, FCN2-LPR1, and TF-TFR2 to mediate visceral fat-liver crosstalk in the context of aging. These findings cast light on how alterations in visceral fat with aging contribute to liver dysfunction and age-related disease etiology.

The roles of tertiary lymphoid structures in chronic diseases

Tertiary lymphoid structures (TLSs) are ectopic lymphoid tissues that drive antigen-specific immune responses at sites of chronic inflammation. Unlike secondary lymphoid organs such as lymph nodes, TLSs lack capsules and have their own unique characteristics and functions. The presumed influence of TLSs on the disease course has led to widespread interest in obtaining a better understanding of their biology and function. Studies using single-cell analyses have suggested heterogeneity in TLS composition and phenotype, and consequently, functional correlates with disease progression are sometimes conflicting. The presence of TLSs correlates with a favourable disease course in cancer and infection. Conversely, in autoimmune diseases and chronic age-related inflammatory diseases including chronic kidney disease, the presence of TLSs is associated with a more severe disease course. However, the detailed mechanisms that underlie these clinical associations are not fully understood. To what extent the mechanisms of TLS development and maturation are shared across organs and diseases is also still obscure. Improved understanding of TLS development and function at the cellular and molecular levels may enable the exploitation of these structures to improve therapies for chronic diseases, including chronic kidney disease.

P53 negatively regulates the osteogenic differentiation in jaw bone marrow MSCs derived from diabetic osteoporosis

Patients with diabetic osteoporosis (DOP) often suffer from poor osseointegration of artificial implants, which is a challenge that affects implant outcomes. The osteogenic differentiation ability of human jaw bone marrow mesenchymal stem cells (JBMMSCs) is the key to implant osseointegration. Studies have shown that the microenvironment of hyperglycemia affects the osteogenic differentiation of mesenchymal stem cells (MSC), but the mechanism is still unclear. Therefore, the aim of this study was to isolate and culture JBMMSCs from surgically derived bone fragments from DOP patients and control patients to investigate the differences in their osteogenic differentiation ability and to elucidate its mechanisms. The results showed that the osteogenic ability of hJBMMSCs was significantly decreased in the DOP environment. Mechanism study showed that the expression of senescence marker gene P53 was significantly increased in DOP hJBMMSCs compared to control hJBMMSCs according to RNA-sequencing result. Further, DOP hJBMMSCs were found to display significant senescence using β-galactosidase staining, mitochondrial membrane potential and ROS assay, qRT-PCR and WB analysis. Overexpression of P53 in hJBMMSCs, knockdown of P53 in DOP hJBMMSCs, and knockdown followed by overexpression of P53 significantly affected the osteogenic differentiation ability of hJBMMSCs. These results suggest that MSC senescence is an important reason for decreasing osteogenic capacity in DOP patients. P53 is a key target in regulating hJBMMSCs aging, and knocking down P53 can effectively restore the osteogenic differentiation ability of DOP hJBMMSCs and promote osteosynthesis in DOP dental implants. It provided a new idea to elucidate the pathogenesis and treatment of diabetic bone metabolic diseases.

Age-dependent Pdgfrβ signaling drives adipocyte progenitor dysfunction to alter the beige adipogenic niche in male mice

Perivascular adipocyte progenitor cells (APCs) can generate cold temperature-induced thermogenic beige adipocytes within white adipose tissue (WAT), an effect that could counteract excess fat mass and metabolic pathologies. Yet, the ability to generate beige adipocytes declines with age, creating a key challenge for their therapeutic potential. Here we show that ageing beige APCs overexpress platelet derived growth factor receptor beta (Pdgfrβ) to prevent beige adipogenesis. We show that genetically deleting Pdgfrβ, in adult male mice, restores beige adipocyte generation whereas activating Pdgfrβ in juvenile mice blocks beige fat formation. Mechanistically, we find that Stat1 phosphorylation mediates Pdgfrβ beige APC signaling to suppress IL-33 induction, which dampens immunological genes such as IL-13 and IL-5. Moreover, pharmacologically targeting Pdgfrβ signaling restores beige adipocyte development by rejuvenating the immunological niche. Thus, targeting Pdgfrβ signaling could be a strategy to restore WAT immune cell function to stimulate beige fat in adult mammals.

Adipose tissue and hematopoiesis: Friend or foe?

AIM

Hematopoietic stem cells are the origin of all hematopoietic cells. They have the self-renewal ability and can differentiate into various blood cells. In physiological state, most of the hematopoietic stem cells are dormant, and only a few cells proliferate to maintain hematopoietic homeostasis.

METHODS

This precise steady-state maintenance is regulated by complex mechanisms. Bone marrow adipocytes make up half of all cells in the bone marrow cavity, a feature that has attracted the attention of researchers from multiple fields. The adipocyte density within marrow increases during aging and obesity.

RESULTS

Recent studies have shown that bone marrow adipocytes play important roles in regulating hematopoiesis, but the effects of bone marrow adipocytes on hematopoiesis are often conflicting. Bone marrow adipocytes, participating in the formation of bone marrow hematopoietic microenvironment, influence hematopoiesis positively or negatively. In addition, other adipose tissue, especially white adipose tissue, also regulates hematopoiesis.

CONCLUSION

In this review, we describe the role of adipose tissue in hematological malignancies, which may be useful for understanding hematopoiesis and the pathogenesis of related diseases.

Increased Fibrosis in White Adipose Tissue of Male and Female bGH Transgenic Mice Appears Independent of TGF-β Action

Fibrosis is a pathological state caused by excess deposition of extracellular matrix proteins in a tissue. Male bovine growth hormone (bGH) transgenic mice experience metabolic dysfunction with a marked decrease in lifespan and with increased fibrosis in several tissues including white adipose tissue (WAT), which is more pronounced in the subcutaneous (Sc) depot. The current study expanded on these initial findings to evaluate WAT fibrosis in female bGH mice and the role of transforming growth factor (TGF)-β in the development of WAT fibrosis. Our findings established that female bGH mice, like males, experience a depot-dependent increase in WAT fibrosis, and bGH mice of both sexes have elevated circulating levels of several markers of collagen turnover. Using various methods, TGF-β signaling was found unchanged or decreased-as opposed to an expected increase-despite the marked fibrosis in WAT of bGH mice. However, acute GH treatments in vivo, in vitro, or ex vivo did elicit a modest increase in TGF-β signaling in some experimental systems. Finally, single nucleus RNA sequencing confirmed no perturbation in TGF-β or its receptor gene expression in any WAT cell subpopulations of Sc bGH WAT; however, a striking increase in B lymphocyte infiltration in bGH WAT was observed. Overall, these data suggest that bGH WAT fibrosis is independent of the action of TGF-β and reveals an intriguing shift in immune cells in bGH WAT that should be further explored considering the increasing importance of B cell-mediated WAT fibrosis and pathology.

Brown Adipose Tissue-A Translational Perspective

Brown adipose tissue (BAT) displays the unique capacity to generate heat through uncoupled oxidative phosphorylation that makes it a very attractive therapeutic target for cardiometabolic diseases. Here, we review BAT cellular metabolism, its regulation by the central nervous and endocrine systems and circulating metabolites, the plausible roles of this tissue in human thermoregulation, energy balance, and cardiometabolic disorders, and the current knowledge on its pharmacological stimulation in humans. The current definition and measurement of BAT in human studies relies almost exclusively on BAT glucose uptake from positron emission tomography with 18F-fluorodeoxiglucose, which can be dissociated from BAT thermogenic activity, as for example in insulin-resistant states. The most important energy substrate for BAT thermogenesis is its intracellular fatty acid content mobilized from sympathetic stimulation of intracellular triglyceride lipolysis. This lipolytic BAT response is intertwined with that of white adipose (WAT) and other metabolic tissues, and cannot be independently stimulated with the drugs tested thus far. BAT is an interesting and biologically plausible target that has yet to be fully and selectively activated to increase the body's thermogenic response and shift energy balance. The field of human BAT research is in need of methods able to directly, specifically, and reliably measure BAT thermogenic capacity while also tracking the related thermogenic responses in WAT and other tissues. Until this is achieved, uncertainty will remain about the role played by this fascinating tissue in human cardiometabolic diseases.

Beyond energy balance regulation: The underestimated role of adipose tissues in host defense against pathogens

Although the adipose tissue (AT) is a central metabolic organ in the regulation of whole-body energy homeostasis, it is also an important endocrine and immunological organ. As an endocrine organ, AT secretes a variety of bioactive peptides known as adipokines - some of which have inflammatory and immunoregulatory properties. As an immunological organ, AT contains a broad spectrum of innate and adaptive immune cells that have mostly been studied in the context of obesity. However, overwhelming evidence supports the notion that AT is a genuine immunological effector site, which contains all cell subsets required to induce and generate specific and effective immune responses against pathogens. Indeed, AT was reported to be an immune reservoir in the host's response to infection, and a site of parasitic, bacterial and viral infections. In addition, besides AT's immune cells, preadipocytes and adipocytes were shown to express innate immune receptors, and adipocytes were reported as antigen-presenting cells to regulate T-cell-mediated adaptive immunity. Here we review the current knowledge on the role of AT and AT's immune system in host defense against pathogens. First, we will summarize the main characteristics of AT: type, distribution, function, and extraordinary plasticity. Second, we will describe the intimate contact AT has with lymph nodes and vessels, and AT immune cell composition. Finally, we will present a comprehensive and up-to-date overview of the current research on the contribution of AT to host defense against pathogens, including the respiratory viruses influenza and SARS-CoV-2.

NLRP3-mediated inflammation in cardio-oncology: sterile yet harmful

Despite significant advances and the continuous development of novel, effective therapies to treat a variety of malignancies, cancer therapy-induced cardiotoxicity has been identified as a prominent cause of morbidity and mortality, closely competing with secondary malignancies. This unfortunate limitation has prompted the inception of the field of cardio-oncology with its purpose to provide the necessary knowledge and key information on mechanisms that support the use of the most efficacious cancer therapy with minimal or no interruption while paying close attention to preventing cardiovascular related morbidity and mortality. Several mechanisms that contribute to cancer therapy-induced cardiotoxicity have been proposed and studied. These mainly involve mitochondrial dysfunction and reactive oxygen species-induced oxidative stress, lysosomal damage, impaired autophagy, cell senescence, DNA damage, and sterile inflammation with the formation and activation of the NLRP3 inflammasome. In this review, we focus on describing the principal mechanisms for different classes of cancer therapies that lead to cardiotoxicity involving the NLRP3 inflammasome. We also summarize current evidence of cardio-protection with inflammasome inhibitors in the context of heart disease in general, and further highlight the potential application of this evidence for clinical translation in at risk patients for the purpose of preventing cancer therapy associated cardiovascular morbidity and mortality.

Mechanic Insight into the Distinct and Common Roles of Ovariectomy Versus Adrenalectomy on Adipose Tissue Remodeling in Female Mice

Dysfunctions of the ovaries and adrenal glands are both evidenced to cause aberrant adipose tissue (AT) remodeling and resultant metabolic disorders, but their distinct and common roles are poorly understood. In this study, through biochemical, histological and RNA-seq analyses, we comprehensively explored the mechanisms underpinning subcutaneous (SAT) and visceral adipose tissue (VAT) remodeling, in response to ovariectomy (OVX) versus adrenalectomy (ADX) in female mice. OVX promoted adipocyte differentiation and fat accumulation in both SAT and VAT, by potentiating the Pparg signaling, while ADX universally prevented the cell proliferation and extracellular matrix organization in both SAT and VAT, likely by inactivating the Nr3c1 signaling, thus causing lipoatrophy in females. ADX, but not OVX, exerted great effects on the intrinsic difference between SAT and VAT. Specifically, ADX reversed a large cluster of genes differentially expressed between SAT and VAT, by activating 12 key transcription factors, and thereby caused senescent cell accumulation, massive B cell infiltration and the development of selective inflammatory response in SAT. Commonly, both OVX and ADX enhance circadian rhythmicity in VAT, and impair cell proliferation, neurogenesis, tissue morphogenesis, as well as extracellular matrix organization in SAT, thus causing dysfunction of adipose tissues and concomitant metabolic disorders.

Aging reduces ABHD5 protein content in the adipose tissue of mice: The reversal effect of exercise

Dysfunction of the adipose tissue metabolism is considered as a significant hallmark of aging. It has been proposed that α-β hydrolase domain containing 5 (ABHD5) plays a critical role in the control of lipolysis. However, the role of ABHD5 in the control of lipolysis during aging or exercise is unknown. Here we combined the experimental mouse model with transcriptomic analyzes by using murine and human databases to explore the role of ABHD5 in the adipose tissue during aging and in response to exercise. Transcriptomic data revealed a downregulation of Abhd5 messenger RNA levels in the subcutaneous white adipose tissue (scWAT) over time in individuals from 20 to 69 years old. Aged mice displayed dramatic reduction of ABHD5 protein content and lipolytic-related proteins in the scWAT. Interestingly, 4 weeks of high-intensity interval training increased ABHD5 protein level and restored the lipolytic pathway in the scWAT of aged mice. Altogether, our findings demonstrated that aging affects ABHD5 content in the adipose tissue of mice and humans. Conversely, exercise increases ABHD5 activity, recovering the lipolytic activity in aged mice.

Chronic Inflammation as an Underlying Mechanism of Ageing and Ageing-Related Diseases

Age-related chronic inflammation is characterized as the unresolved low-grade inflammatory process underlying the ageing process and various age-related diseases. In this chapter, we review the age-related changes in the oxidative stress-sensitive pro-inflammatory NF-κB signaling pathways causally linked with chronic inflammation during ageing based on senoinflammation schema. We describe various age-related dysregulated pro- and anti-inflammatory cytokines, chemokines, and senescence-associated secretory phenotype (SASP), and alterations of inflammasome, specialized pro-resolving lipid mediators (SPM), and autophagy as major players in the chronic inflammatory intracellular signaling network. A better understanding of the molecular, cellular, and systemic mechanisms involved in chronic inflammation in the ageing process would provide further insights into the potential anti-inflammatory strategies.