Identification and Characterization of Adipose Tissue-Derived Human Antibodies With "Anti-self" Specificity

Therapeutic targeting of white adipose tissue metabolic dysfunction in obesity: mechanisms and opportunities

White adipose tissue is not only a highly heterogeneous organ containing various cells, such as adipocytes, adipose stem and progenitor cells, and immune cells, but also an endocrine organ that is highly important for regulating metabolic and immune homeostasis. In individuals with obesity, dynamic cellular changes in adipose tissue result in phenotypic switching and adipose tissue dysfunction, including pathological expansion, WAT fibrosis, immune cell infiltration, endoplasmic reticulum stress, and ectopic lipid accumulation, ultimately leading to chronic low-grade inflammation and insulin resistance. Recently, many distinct subpopulations of adipose tissue have been identified, providing new insights into the potential mechanisms of adipose dysfunction in individuals with obesity. Therefore, targeting white adipose tissue as a therapeutic agent for treating obesity and obesity-related metabolic diseases is of great scientific interest. Here, we provide an overview of white adipose tissue remodeling in individuals with obesity including cellular changes and discuss the underlying regulatory mechanisms of white adipose tissue metabolic dysfunction. Currently, various studies have uncovered promising targets and strategies for obesity treatment. We also outline the potential therapeutic signaling pathways of targeting adipose tissue and summarize existing therapeutic strategies for antiobesity treatment including pharmacological approaches, lifestyle interventions, and novel therapies.

A review on separation and application of plant-derived exosome-like nanoparticles

Exosomes-like nanoparticles (ELNs) (exosomes or extracellular vesicles) are vesicle-like bodies secreted by cells. Plant ELNs (PENs) are membrane vesicles secreted by plant cells, with a lipid bilayer as the basic skeleton, enclosing various active substances such as proteins and nucleic acids, which have many physiological and pathological functions. Recent studies have found that the PENs are widespread within different plant species and their biological functions are increasingly recognized. The effective separation method is also necessary for its function and application. Ultracentrifugation, sucrose density gradient ultracentrifugation, ultrafiltration, polymer-based precipitation methods, etc., are commonly used methods for plant exosome-like nanoparticle extraction. In recent years, emerging methods such as size exclusion chromatography, immunoaffinity capture-based technique, and microfluidic technology have shown advancements compared to traditional methods. The standardized separation process for PENs continues to evolve. In this review, we summarized the recent progress in the biogenesis, components, separation methods, and some functions of PENs. When the research on the separation method of PENs and their unique biological structure is further studied. A brand-new idea for the efficient separation and utilization of PENs can be provided in the future, which has a very broad prospect.

Adipose failure through adipocyte overload and autoimmunity

Metabolic syndrome poses a great worldwide threat to the health of the patients. Increased visceral adiposity is recognized as the main determinant of the detrimental clinical effects of insulin resistance. Inflammation and immune system activation in the adipose tissue (AT) have a central role in the pathophysiology of metabolic syndrome, but the mechanisms linking increased adiposity to immunity in the AT remain in part elusive. In this review, we support the central role of adipocyte overload and relative adipose failure as key determinants in triggering immune aggression to AT. This provides a mechanistic explanation of the relative metabolic wellness of metabolically normal obese people and the disruption in insulin signaling in metabolically obese lean people.

B cell contribution to immunometabolic dysfunction and impaired immune responses in obesity

Obesity increases the risk of type 2 diabetes mellitus, cardiovascular disease, fatty liver disease, and cancer. It is also linked with more severe complications from infections, including COVID-19, and poor vaccine responses. Chronic, low-grade inflammation and associated immune perturbations play an important role in determining morbidity in people living with obesity. The contribution of B cells to immune dysregulation and meta-inflammation associated with obesity has been documented by studies over the past decade. With a focus on human studies, here we consolidate the observations demonstrating that there is altered B cell subset composition, differentiation, and function both systemically and in the adipose tissue of individuals living with obesity. Finally, we discuss the potential factors that drive B cell dysfunction in obesity and propose a model by which altered B cell subset composition in obesity underlies dysfunctional B cell responses to novel pathogens.

Regulation of immune cell metabolism in health and disease: Special focus on T and B cell subsets

Metabolism is a dynamic process and keeps changing from time to time according to the demand of a particular cell to meet its bio-energetic requirement. Different immune cells rely on distinct metabolic programs which allow the cell to balance its requirements for energy, molecular biosynthesis, and effector activity. In the aspect of infection and cancer immunology, effector T and B cells get exhausted and help tumor cells to evade immunosurveillance. On the other hand, T cells become hyperresponsive in the scenario of autoimmune diseases. In this article, we have explored the uniqueness and distinct metabolic features of key CD4⁺ T and B helper cell subsets, CD4⁺ T, B regulatory cell subsets and CD8⁺ T cells regarding health and disease. Th1 cells rely on glycolysis and glutaminolysis; inhibition of these metabolic pathways promotes Th1 cells in Treg population. However, Th2 cells are also dependent on glycolysis but an abundance of lactate within TME shifts their metabolic dependency to fatty acid metabolism. Th17 cells depend on HIF-1α mediated glycolysis, ablation of HIF-1α reduces Th17 cells but enhance Treg population. In contrast to effector T cells which are largely dependent on glycolysis for their differentiation and function, Treg cells mainly rely on FAO for their function. Therefore, it is of utmost importance to understand the metabolic fates of immune cells and how it facilitates their differentiation and function for different disease models. Targeting metabolic pathways to restore the functionality of immune cells in diseased conditions can lead to potent therapeutic measures.

The Endocrine Adipose Organ: A System Playing a Central Role in COVID-19

In the last 30 years the adipose cell has been object of several studies, turning its reputation from an inert cell into the main character involved in the pathophysiology of multiple diseases, including the ongoing COVID-19 pandemic, which has changed the clinical scenario of the last two years. Composed by two types of tissue (white and brown), with opposite roles, the adipose organ is now classified as a real endocrine organ whose dysfunction is involved in different diseases, mainly obesity and type 2 diabetes. In this mini-review we aim to retrace the adipose organ history from physiology to physiopathology, to provide therapeutic perspectives for the prevention and treatment of its two main related diseases (obesity and type 2 diabetes) and to summarize the most recent discoveries linking adipose tissue to COVID-19.

Immune and non-immune functions of adipose tissue leukocytes

Adipose tissue is a complex dynamic organ with whole-body immunometabolic influence. Much of the work into understanding the role of immune cells in adipose tissue has been in the context of obesity. These investigations have also uncovered a range of typical (immune) and non-typical functions exerted by adipose tissue leukocytes. Here we provide an overview of the adipose tissue immune system, including its role as an immune reservoir in the whole-body response to infection and as a site of parasitic and viral infections. We also describe the functional roles of specialized immunological structures found within adipose tissue. However, our main focus is on the recently discovered 'non-immune' functions of adipose tissue immune cells, which include the regulation of adipocyte homeostasis, as well as responses to changing nutrient status and body temperature. In doing so, we outline the therapeutic potential of the adipose tissue immune system in health and disease.

Obesity Accelerates Age Defects in Human B Cells and Induces Autoimmunity +

Aging is associated with systemic inflammation and decreased production of protective antibodies while the production of autoimmune antibodies is increased. Our results have shown that the human obese adipose tissue (AT), which increases in size with aging, contributes to systemic and B cell intrinsic inflammation, reduced protective and increased pathogenic B cell responses leading to increased secretion of autoimmune antibodies.

With this R56 funding, we have been able to investigate the cellular and molecular mechanisms by which the human obese AT induces intrinsic B cell inflammation and dysfunctional B cell responses, stimulates the secretion of autoimmune antibodies, whose specificity has been characterized, and engages different AT cell types in antigen presentation pathways to allow secretion of these autoimmune antibodies. Briefly, immune cells are recruited to the AT by chemokines released by both non-immune (adipocytes) and by resident and infiltrating immune cells. We have identified several mechanisms responsible for the release of “self” antigens, and we have shown that reduced oxygen availability and hypoxia, cell cytotoxicity and DNA damage induce cell death and lead to further release of pro-inflammatory cytokines, “self” protein antigens, cell-free DNA and lipids. We have also identified different antigen presenting cells in the AT, responsible for the activation of pathogenic B cells, class switch and secretion of autoimmune IgG antibodies. The experiments performed have allowed the discovery of novel mechanisms for pathogenic responses and the identification of pathways to target in order to promote better humoral immunity during aging.

Mechanisms contributing to adverse outcomes of COVID-19 in obesity

A growing amount of epidemiological data from multiple countries indicate an increased prevalence of obesity, more importantly central obesity, among hospitalized subjects with COVID-19. This suggests that obesity is a major factor contributing to adverse outcome of the disease. As it is a metabolic disorder with dysregulated immune and endocrine function, it is logical that dysfunctional metabolism contributes to the mechanisms behind obesity being a risk factor for adverse outcome in COVID-19. Emerging data suggest that in obese subjects, (a) the molecular mechanisms of viral entry and spread mediated through ACE2 receptor, a multifunctional host cell protein which links to cellular homeostasis mechanisms, are affected. This includes perturbation of the physiological renin-angiotensin system pathway causing pro-inflammatory and pro-thrombotic challenges (b) existent metabolic overload and ER stress-induced UPR pathway make obese subjects vulnerable to severe COVID-19, (c) host cell response is altered involving reprogramming of metabolism and epigenetic mechanisms involving microRNAs in line with changes in obesity, and (d) adiposopathy with altered endocrine, adipokine, and cytokine profile contributes to altered immune cell metabolism, systemic inflammation, and vascular endothelial dysfunction, exacerbating COVID-19 pathology. In this review, we have examined the available literature on the underlying mechanisms contributing to obesity being a risk for adverse outcome in COVID-19.

Obesity Accelerates Age-Associated Defects in Human B Cells Through a Metabolic Reprogramming Induced by the Fatty Acid Palmitate

We have measured the secretion of autoimmune antibodies in plasma samples and in culture supernatants of blood-derived B cells from four groups of individuals: young lean (Y_L), elderly lean (E_L), young obese (Y_O) and elderly obese (E_O). We found secretion comparable in Y_O and E_L individuals, suggesting that obesity accelerates age-associated defects in circulating B cells. To define at least one possible molecular pathway involved, we used an in vitro model in which B cells from Y_L and E_L individuals have been stimulated with the Fatty Acid (FA) palmitate, the most common saturated FA in the human body. The rationale to use palmitate is that there is a chronic increase in circulating levels of palmitate, due to increased spontaneous lipolysis occurring during aging and obesity, and this may induce autoimmune B cells. Results herein show that in vitro incubation of B cells from Y_L and E_L individuals with the FA palmitate induces mRNA expression of T-bet, the transcription factor for autoimmune antibodies, as well as secretion of autoimmune IgG antibodies, with B cells from Y_L individuals looking similar to B cells from E_L individuals, confirming our initial hypothesis. The generation of autoimmune B cells in the presence of the FA palmitate was found to be associated with a metabolic reprogramming of B cells from both Y_L and E_L individuals. These results altogether show the critical role of the FA palmitate in inducing human B cell immunosenescence and show for the first time the importance of metabolic pathways in this process.

The majority of SARS-CoV-2-specific antibodies in COVID-19 patients with obesity are autoimmune and not neutralizing

BACKGROUND/OBJECTIVES

Obesity decreases the secretion of SARS-CoV-2-specific IgG antibodies in the blood of COVID-19 patients. How obesity impacts the quality of the antibodies secreted, however, is not understood. Therefore, the objective of this study is to evaluate the presence of neutralizing versus autoimmune antibodies in COVID-19 patients with obesity.

SUBJECTS/METHODS

Thirty serum samples from individuals who tested positive for SARS-CoV-2 infection by RT-PCR were collected from inpatient and outpatient settings. Of these, 15 were lean (BMI < 25) and 15 were obese (BMI ≥ 30). Control serum samples were from 30 uninfected individuals, age-, gender-, and BMI-matched, recruited before the current pandemic. Neutralizing and autoimmune antibodies were measured by ELISA. IgG autoimmune antibodies were specific for malondialdehyde (MDA), a marker of oxidative stress and lipid peroxidation, and for adipocyte-derived protein antigens (AD), markers of virus-induced cell death in the obese adipose tissue.

RESULTS

SARS-CoV-2 infection induces neutralizing antibodies in all lean but only in few obese COVID-19 patients. SARS-CoV-2 infection also induces anti-MDA and anti-AD autoimmune antibodies more in lean than in obese patients as compared to uninfected controls. Serum levels of these autoimmune antibodies, however, are always higher in obese versus lean COVID-19 patients. Moreover, because the autoimmune antibodies found in serum samples of COVID-19 patients have been correlated with serum levels of C-reactive protein (CRP), a general marker of inflammation, we also evaluated the association of anti-MDA and anti-AD antibodies with serum CRP and found a positive association between CRP and autoimmune antibodies.

CONCLUSIONS

Our results highlight the importance of evaluating the quality of the antibody response in COVID-19 patients with obesity, particularly the presence of autoimmune antibodies, and identify biomarkers of self-tolerance breakdown. This is crucial to protect this vulnerable population at higher risk of responding poorly to infection with SARS-CoV-2 than lean controls.

Autoimmune Inflammation and Insulin Resistance: Hallmarks So Far and Yet So Close to Explain Diabetes Endotypes

PURPOSE OF REVIEW

Diabetes mellitus can be categorized into two major variants, type 1 and type 2. A number of traits such as clinical phenotype, age at disease onset, genetic background, and underlying pathogenesis distinguish the two forms.

RECENT FINDINGS

Recent evidence indicates that type 1 diabetes can be accompanied by insulin resistance and type 2 diabetes exhibits self-reactivity. These two previously unknown conditions can influence the progression and outcome of the disease. Unlike most conventional considerations, diabetes appears to consist of a spectrum of intermediate phenotypes that includes monogenic and polygenic loci linked to inflammatory processes including autoimmunity, beta cell impairment, and insulin resistance. Here we discuss why a shift of the classical bi-modal view of diabetes (autoimmune vs. non-autoimmune) is necessary in favor of a model of an immunological continuum of endotypes lying between the two extreme "insulin-resistant" and "autoimmune beta cell targeting," shaped by environmental and genetic factors which contribute to determine specific immune-conditioned outcomes.

The Emerging Role of B Cells in the Pathogenesis of NAFLD

NAFLD is one of the leading causes of abnormal liver function worldwide. NAFLD refers to a group of liver conditions ranging from nonalcoholic fatty liver to NASH, which involves inflammation, hepatocellular damage, and fibrosis. Triggering of inflammation in NASH is a key event in the progression of the disease, and identifying the factors that initiate or dysregulate this process is needed to develop strategies for its prevention or treatment. B cells have been implicated in several autoimmune and inflammatory diseases. However, their role in the pathogenesis of NAFLD and NASH is less clear. This review discusses the emerging evidence implicating intrahepatic B cells in the progression of NAFLD. We highlight the potential mechanisms of B-cell activation during NAFLD, such as increased hepatic expression of B-cell-activating factor, augmented oxidative stress, and translocation of gut-derived microbial products. We discuss the possible effector functions by which B cells promote NAFLD, including the production of proinflammatory cytokines and regulation of intrahepatic T cells and macrophages. Finally, we highlight the role of regulatory and IgA⁺ B cells in the pathogenesis of NASH-associated HCC. In this review, we make the case that future research is needed to investigate the potential of B-cell-targeting strategies for the treatment of NAFLD.

B Cell Immunosenescence

Innate and adaptive immune responses decline with age, leading to greater susceptibility to infectious diseases and reduced responses to vaccines. Diseases are more severe in old than in young individuals and have a greater impact on health outcomes such as morbidity, disability, and mortality. Aging is characterized by increased low-grade chronic inflammation, so-called inflammaging, that represents a link between changes in immune cells and a number of diseases and syndromes typical of old age. In this review we summarize current knowledge on age-associated changes in immune cells with special emphasis on B cells, which are more inflammatory and less responsive to infections and vaccines in the elderly. We highlight recent findings on factors and pathways contributing to inflammaging and how these lead to dysfunctional immune responses. We summarize recent published studies showing that adipose tissue, which increases in size with aging, contributes to inflammaging and dysregulated B cell function.

SARS-CoV-2 infection induces autoimmune antibody secretion more in lean than in obese COVID-19 patients

BACKGROUND/OBJECTIVES

Obesity decreases the secretion of SARS-CoV-2-specific IgG antibodies in the blood of COVID-19 patients. How obesity impacts the secretion of autoimmune antibodies in COVID-19 patients, however, is not understood. The serum of adult COVID-19 patients contains autoimmune antibodies generated in response to virus-induced tissue damage and cell death leading to the release of intracellular antigens not known to be immunogenic autoantigens. The objective of this study is to evaluate the presence of autoimmune antibodies in COVID-19 patients with obesity.

SUBJECTS/METHODS

Thirty serum samples from individuals who tested positive for SARS-CoV-2 infection by RT-PCR were collected from inpatient and outpatient settings. Of these, 15 were lean (BMI<25), and 15 were obese (BMI ≥30). Control serum samples were from 30 uninfected individuals, age-gender- and BMI-matched, recruited before the current pandemic. Serum IgG antibodies against two autoimmune specificities, as well as against SARS-CoV-2 Spike protein, were measured by ELISA. IgG autoimmune antibodies were specific for malondialdehyde (MDA), a marker of oxidative stress and lipid peroxidation, and for adipocyte-derived protein antigens (AD), markers of virus-induced cell death in the obese AT.

RESULTS

Our results show that SARS-CoV-2 infection induces anti-MDA and anti-AD autoimmune antibodies more in lean than in obese patients as compared to uninfected controls. Serum levels of these autoimmune antibodies, however, are always higher in obese versus lean COVID-19 patients. Moreover, because the autoimmune antibodies found in serum samples of COVID-19 patients have been correlated with serum levels of C-reactive protein (CRP), a general marker of inflammation, we also evaluated the association of anti-MDA and anti-AT antibodies with serum CRP and found a significant association between CRP and autoimmune antibodies in our cohort of lean and obese COVID-19 patients.

CONCLUSIONS

Our results highlight the importance of evaluating the quality of the antibody response in COVID-19 patients with obesity, particularly the presence of autoimmune antibodies, and identify biomarkers of self-tolerance breakdown. This is crucial to protect this vulnerable population that is at higher risk of responding poorly to infection with SARS-CoV-2 compared to lean controls.

Influence of obesity on serum levels of SARS-CoV-2-specific antibodies in COVID-19 patients

SARS-CoV-2 (Severe Acute Respiratory Syndrome Corona Virus-2), cause of COVID-19 (Coronavirus Disease of 2019), represents a significant risk to people living with pre-existing conditions associated with exacerbated inflammatory responses and consequent dysfunctional immunity. In this paper, we have evaluated the influence of obesity, a condition associated with chronic systemic inflammation, on the secretion of SARS-CoV-2-specific IgG antibodies in the blood of COVID-19 patients. Our hypothesis is that obesity is associated with reduced amounts of specific IgG antibodies. Results have confirmed our hypothesis and have shown that SARS-CoV-2 IgG antibodies are negatively associated with Body Mass Index (BMI) in COVID-19 obese patients, as expected based on the known influence of obesity on humoral immunity. Antibodies in COVID-19 obese patients are also negatively associated with serum levels of pro-inflammatory and metabolic markers of inflammaging and pulmonary inflammation, such as SAA (serum amyloid A protein), CRP (C-reactive protein), and ferritin, but positively associated with NEFA (nonesterified fatty acids). These results altogether could help to identify an inflammatory signature with strong predictive value for immune dysfunction. Inflammatory markers identified may subsequently be targeted to improve humoral immunity in individuals with obesity and in individuals with other chronic inflammatory conditions.

Hyper-metabolic B cells in the spleens of old mice make antibodies with autoimmune specificities

BACKGROUND

Aging is associated with increased intrinsic B cell inflammation, decreased protective antibody responses and increased autoimmune antibody responses. The effects of aging on the metabolic phenotype of B cells and on the metabolic programs that lead to the secretion of protective versus autoimmune antibodies are not known.

METHODS

Splenic B cells and the major splenic B cell subsets, Follicular (FO) and Age-associated B cells (ABCs), were isolated from the spleens of young and old mice and left unstimulated. The RNA was collected to measure the expression of markers associated with intrinsic inflammation and autoimmune antibody production by qPCR. B cells and B cell subsets were also stimulated with CpG and supernatants collected after 7 days to measure autoimmune IgG secretion by ELISA. Metabolic measures (oxygen consumption rate, extracellular acidification rate and glucose uptake) were performed using a Seahorse XFp extracellular flux analyzer.

RESULTS

Results have identified the subset of ABCs, whose frequencies and numbers increase with age and represent the most pro-inflammatory B cell subset, as the cell type mainly if not exclusively responsible for the expression of inflammatory markers and for the secretion of autoimmune antibodies in the spleen of old mice. Hyper-inflammatory ABCs from old mice are also hyper-metabolic, as compared to those from young mice and to the subset of FO B cells, a feature needed not only to support their higher expression of RNA for inflammatory markers but also their higher autoimmune antibody secretion.

CONCLUSIONS

These results identify a relationship between intrinsic inflammation, metabolism and autoimmune B cells and suggest possible ways to understand cellular mechanisms that lead to the generation of pathogenic B cells, that are hyper-inflammatory and hyper-metabolic, and secrete IgG antibodies with autoimmune specificities.

Phenotypic and Functional Characterization of Double Negative B Cells in the Blood of Individuals With Obesity

We have previously shown that obesity is associated with increased secretion of IgG antibodies with anti-self-reactivity. In this paper, we confirm and extend our previous findings. We show that the plasma of individuals with obesity is enriched in autoimmune antibodies whose levels are positively associated with blood frequencies of the subset of Double Negative (DN) B cells, which is the most pro-inflammatory B cell subset. We also show that DN B cells, significantly increased in the blood of obese versus lean individuals, are characterized by higher expression of immune activation markers and of the transcription factor T-bet, both associated with autoimmunity. The removal of DN B cells from the peripheral B cell pool significantly decreases in vitro secretion of anti-self IgG antibodies. These results altogether confirm the crucial role of DN B cells in the secretion of anti-self IgG antibodies in individuals with obesity.

B Cells with a Senescent-Associated Secretory Phenotype Accumulate in the Adipose Tissue of Individuals with Obesity

Senescent cells accumulate in the adipose tissue (AT) of individuals with obesity and secrete multiple factors that constitute the senescence-associated secretory phenotype (SASP). This paper aimed at the identification of B cells with a SASP phenotype in the AT, as compared to the peripheral blood, of individuals with obesity. Our results show increased expression of SASP markers in AT versus blood B cells, a phenotype associated with a hyper-metabolic profile necessary to support the increased immune activation of AT-derived B cells as compared to blood-derived B cells. This hyper-metabolic profile is needed for the secretion of the pro-inflammatory mediators (cytokines, chemokines, micro-RNAs) that fuel local and systemic inflammation.

Effects of obesity on serum levels of SARS-CoV-2-specific antibodies in COVID-19 patients

SARS-CoV-2 (Severe Acute Respiratory Syndrome Corona Virus-2), cause of COVID-19 (Coronavirus Disease of 2019), represents a significant risk to people living with pre-existing conditions associated with exacerbated inflammatory responses and consequent dysfunctional immunity. In this paper, we have evaluated the effects of obesity, a condition associated with chronic systemic inflammation, on the secretion of SARS-CoV-2-specific IgG antibodies in the blood of COVID-19 patients. Results have shown that SARS-CoV-2 IgG antibodies are negatively associated with Body Mass Index (BMI) in COVID-19 obese patients, as expected based on the known effects of obesity on humoral immunity. Antibodies in COVID-19 obese patients are also negatively associated with serum levels of pro-inflammatory and metabolic markers of inflammaging and pulmonary inflammation, such as SAA (serum amyloid A protein), CRP (C-reactive protein) and ferritin, but positively associated with NEFA (nonesterified fatty acids). These results altogether could help to identify an inflammatory signature with strong predictive value for immune dysfunction that could be targeted to improve humoral immunity in individuals with obesity as well as with other chronic inflammatory conditions.

Obesity Accelerates Age Defects in Mouse and Human B Cells

Obesity, similar to aging, is associated with chronic low-grade systemic inflammation, known as inflammaging, and represents a significantly higher risk for developing chronic diseases typical of old age. Immune cells are recruited to the obese adipose tissue (AT) by chemotactic molecules secreted by non-immune and immune cells in the AT, both contributing to the release of several pro-inflammatory mediators that fuel local and systemic inflammation, to the refractory response of immune cells to further in vivo and in vitro stimulation and to the induction of autoimmune B cells with potentially pathogenic repertoires. In terms of molecular mechanisms involved, leptin, an adipokine secreted primarily by adipocytes, has been proposed to be involved in the reduced generation of protective antibodies, and in the increased generation of autoimmune antibodies, further supporting the concept that obesity accelerates age defects. Leptin has also been shown to induce intrinsic B cell inflammation and B cell immunosenescence. The results presented in this review highlight the importance of weight reduction programs to improve immunity and reduce the risk for developing chronic diseases in obese and older individuals.

The Immune Landscape of Visceral Adipose Tissue During Obesity and Aging

Obesity and aging represent major health burdens to the global adult population. Both conditions promote the development of associated metabolic diseases such as insulin resistance. The visceral adipose tissue (VAT) is a site that becomes dysfunctional during obesity and aging, and plays a significant role during their pathophysiology. The changes in obese and aging VAT are now recognized to be partly driven by a chronic local inflammatory state, characterized by immune cells that typically adopt an inflammatory phenotype during metabolic disease. Here, we summarize the current knowledge on the immune cell landscape of the VAT during lean, obese, and aged conditions, highlighting their similarities and differences. We also briefly discuss possible linked mechanisms that fuel obesity- and age-associated VAT dysfunction.