Adipocyte death defines macrophage localization and function in adipose tissue of obese mice and humans

Eva1 deficiency prevents obesity-induced metabolic disorders by reducing visceral adipose dysfunction

AIMS

Epithelial V-like antigen 1 (Eva1) is a highly specific marker for brown adipose tissue (BAT) in both mice and humans, but its metabolic function remains unclear. We investigated the impact of Eva1 deletion on the development of obesity.

METHODS

To assess the metabolic role of Eva1, we generated whole-body and adipocyte-specific Eva1knockout (KO) mice, which were subjected to a high-fat diet (HFD) for 12 weeks and characterized metabolic phenotypes. To further elucidate the depot-dependent impact of Eva1 deficiency, we performed histological analysis and 3' mRNA-seq of BAT and epididymal visceral white adipose tissue (eWAT). To investigate the role of macrophage-derived Eva1 in obesity development, we transplanted wild-type (WT) or Eva1KO macrophages into Eva1KO mice fed an HFD.

RESULTS

We found that whole-body Eva1KO mice are resistant to HFD-induced obesity, insulin resistance and visceral adipose inflammation. However, Eva1 deletion in adipocytes, both brown and white, did not phenocopy these protective effects. Notably, whole-body Eva1 deficiency triggers functional changes in eWAT, but not in BAT. These results led us to investigate a possible involvement of macrophages in Eva1-mediated obesity regulation. We found that Eva1 is expressed in macrophages and plays a role in lipopolysaccharide (LPS)-induced inflammatory responses, possibly through the direct interaction with toll-like receptor 4 (TLR4). Moreover, Eva1KO mice exhibited improved survival rates in the face of severe sepsis induced by LPS. Importantly, transplantation of WT macrophages to Eva1KO mice abolished the beneficial effects of whole-body Eva1 deletion against obesity and visceral adipose inflammation.

CONCLUSION

Our findings highlight macrophage-derived Eva1 as an important mediator in obesity-induced eWAT remodeling, suggesting that targeting Eva1 could offer a novel therapeutic strategy for obesity-related metabolic disorders.

TREM2 as a regulator of obesity-induced cardiac remodeling: mechanisms and therapeutic insights

Obesity and type 2 diabetes mellitus (T2DM) are global health challenges that significantly increase the risk of cardiovascular diseases (CVD). Advances in immunometabolism have identified triggering receptor expressed on myeloid cells 2 (TREM2) as a key regulator of macrophage function, lipid metabolism, and inflammation resolution. Although extensively studied in neurodegenerative diseases, TREM2's role in metabolic disorders and cardiovascular health is an emerging area of research. This review explores TREM2's molecular structure and functions, emphasizing its contributions to immunometabolic regulation in obesity and T2DM. Evidence from preclinical models demonstrates that TREM2 modulates macrophage-driven inflammatory responses, lipid clearance, plaque stability, fibrosis, and myocardial remodeling. Translational findings suggest that TREM2 expression correlates with cardiometabolic outcomes, underscoring its potential as a therapeutic target. Key knowledge gaps include TREM2's temporal dynamics during disease progression, sex-specific effects, and interactions with recruited or resident macrophage activation in obesity and T2DM. Integrating mechanistic and translational insights is critical to harness TREM2's immunoregulatory potential for improving CVD outcomes in metabolic disorders.

Pyroptosis: A spoiler of peaceful coexistence between cells in degenerative bone and joint diseases

BACKGROUND

As people age, degenerative bone and joint diseases (DBJDs) become more prevalent. When middle-aged and elderly people are diagnosed with one or more disorders such as osteoporosis (OP), osteoarthritis (OA), and intervertebral disc degeneration (IVDD), it often signals the onset of prolonged pain and reduced functionality. Chronic inflammation has been identified as the underlying cause of various degenerative diseases, including DBJDs. Recently, excessive activation of pyroptosis, a form of programed cell death (PCD) mediated by inflammasomes, has emerged as a primary driver of harmful chronic inflammation. Consequently, pyroptosis has become a potential target for preventing and treating DBJDs.

AIM OF REVIEW

This review explored the physiological and pathological roles of the pyroptosis pathway in bone and joint development and its relation to DBJDs. Meanwhile, it elaborated the molecular mechanisms of pyroptosis within individual cell types in the bone marrow and joints, as well as the interplay among different cell types in the context of DBJDs. Furthermore, this review presented the latest compelling evidence supporting the idea of regulating the pyroptosis pathway for DBJDs treatment, and discussed the potential, limitations, and challenges of various therapeutic strategies involving pyroptosis regulation.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In summary, an interesting identity for the unregulated pyroptosis pathway in the context of DBJDs was proposed in this review, which was undertaken as a spoiler of peaceful coexistence between cells in a degenerative environment. Over the extended course of DBJDs, pyroptosis pathway perpetuated its activity through crosstalk among pyroptosis cascades in different cell types, thus exacerbating the inflammatory environment throughout the entire bone marrow and joint degeneration environment. Correspondingly, pyroptosis regulation therapy emerged as a promising option for clinical treatment of DBJDs.

Insulin‑like growth factor 2 in spermatogenesis dysfunction (Review)

Spermatogenesis dysfunction is characterized by abnormal morphology, destruction, atrophy of seminiferous tubules, blocked differentiation of spermatogenic cells, decreased sperm count and increased sperm abnormalities. Inflammation, oxidative stress, endoplasmic reticulum stress and obesity are important factors leading to spermatogenesis dysfunction. It has been demonstrated that insulin‑like growth factor 2 (IGF2) is closely related to the aforementioned factors. In the present review, the relationship between IGF2 and inflammation, oxidative stress, ER stress and obesity was investigated, providing theoretical and experimental evidence on the role of IGF2 in the prevention and treatment of spermatogenesis dysfunction of male infertility.

Curcumin Modulation of the Gut-Brain Axis for Neuroinflammation and Metabolic Disorders Prevention and Treatment

Curcumin, a polyphenolic compound derived from Curcuma longa, has gained significant attention for its potential therapeutic benefits, particularly counteracting inflammation, oxidative stress, and metabolic disorders. Its chemical structure, featuring conjugated double bonds between two aromatic rings, allows it to act as an electron donor, thereby mitigating free radical formation. Despite its poor solubility in water, curcumin is stable in acidic environments and undergoes significant metabolism in both the liver and the gut. Intestinal microbiota, particularly at the colon level, further metabolizes curcumin into several derivatives, including dihydrocurcumin and tetrahydrocurcumin, which exhibit antioxidant and anti-inflammatory properties. Studies suggest that curcumin can reduce body mass index (BMI) and improve other body composition parameters, especially when used in combination with lifestyle changes, though its bioavailability is low due to its rapid metabolism and the resulting low blood concentration. In obesity, dysfunctional adipose tissue remodeling and chronic inflammation play critical roles in the development of metabolic complications. Curcumin's anti-inflammatory properties are related to the inhibition of the NF-κB pathway, leading to the reduction in inflammatory markers in adipocytes and macrophages. Additionally, curcumin modulates oxidative stress by activating the NRF2 pathway, enhancing cellular antioxidant defenses. Emerging evidence also supports curcumin's potential in improving gut health by modulating microbiota composition, enhancing intestinal barrier function, and reducing systemic inflammation. This interaction with the gut-brain axis highlights the broader implications of curcumin in neuroprotection, as it positively affects cognitive function and mitigates neuroinflammation in neurodegenerative diseases like Alzheimer's. disease. Thus, curcumin holds promise as a multifaceted agent in the management of obesity and associated diseases.

Targeting IRE1α improves insulin sensitivity and thermogenesis and suppresses metabolically active adipose tissue macrophages in male obese mice

Overnutrition engenders the expansion of adipose tissue and the accumulation of immune cells, in particular, macrophages, in the adipose tissue, leading to chronic low-grade inflammation and insulin resistance. In obesity, several proinflammatory subpopulations of adipose tissue macrophages (ATMs) identified hitherto include the conventional 'M1-like' CD11C-expressing ATM and the newly discovered metabolically activated CD9-expressing ATM; however, the relationship among ATM subpopulations is unclear. The ER stress sensor inositol-requiring enzyme 1α (IRE1α) is activated in the adipocytes and immune cells under obesity. It is unknown whether targeting IRE1α is capable of reversing insulin resistance and obesity and modulating the metabolically activated ATMs. We report that pharmacological inhibition of IRE1α RNase significantly ameliorates insulin resistance and glucose intolerance in male mice with diet-induced obesity. IRE1α inhibition also increases thermogenesis and energy expenditure, and hence protects against high fat diet-induced obesity. Our study shows that the 'M1-like' CD11c+ ATMs are largely overlapping with but yet non-identical to CD9+ ATMs in obese white adipose tissue. Notably, IRE1α inhibition diminishes the accumulation of obesity-induced metabolically activated ATMs and 'M1-like' ATMs, resulting in the curtailment of adipose inflammation and ensuing reactivation of thermogenesis, without augmentation of the alternatively activated M2 macrophage population. Our findings suggest the potential of targeting IRE1α for the therapeutic treatment of insulin resistance and obesity.

Life-threatening risk factors contribute to the development of diseases with the highest mortality through the induction of regulated necrotic cell death

Chronic diseases affecting the cardiovascular system, diabetes mellitus, neurodegenerative diseases, and various other organ-specific conditions, involve different underlying pathological processes. However, they share common risk factors that contribute to the development and progression of these diseases, including air pollution, hypertension, obesity, high cholesterol levels, smoking and alcoholism. In this review, we aim to explore the connection between four types of diseases with different etiologies and various risk factors. We highlight that the presence of risk factors induces regulated necrotic cell death, leading to the release of damage-associated molecular patterns (DAMPs), ultimately resulting in sterile inflammation. Therefore, DAMP-mediated inflammation may be the link explaining how risk factors can lead to the development and maintenance of chronic diseases. To explore these processes, we summarize the main cell death pathways activated by the most common life-threatening risk factors, the types of released DAMPs and how these events are associated with the pathophysiology of diseases with the highest mortality. Various risk factors, such as smoking, air pollution, alcoholism, hypertension, obesity, and high cholesterol levels induce regulated necrosis. Subsequently, the release of DAMPs leads to chronic inflammation, which increases the risk of many diseases, including those with the highest mortality rates.

Converted Macrophage Polarization and Expression of COL6α3-Early Predictors of Remodeling Processes in Adipose Tissue of Male Children

Background/Objectives: Overweight and obesity in early childhood is a serious public health problem as in most cases it persists into adulthood and significantly affects the quality of life. The aim of this study was to investigate the mechanisms that trigger extracellular matrix (ECM) remodeling in the subcutaneous (SAT) and visceral (VAT) adipose tissue of male children in relation to their body weight. Methods: During elective abdominal surgery, SAT and VAT were acquired from 75 male subjects undergoing hernia repair (inguinal herniorrhaphy by Ferguson) or orchidopexy. Based on their Z-score, subjects were separated into two groups. The morphometry of both adipose tissue compartments was assessed after hematoxylin and eosin histological staining, immunohistochemistry to quantify CD163+ cells and the number of crown-like structures (CLSs), and real-time polymerase chain reaction to assess the relative gene expression for collagen VI subtype alpha 3 (COL6α3). Results: Obese and overweight individuals were found to have higher numbers of CD163+ cells, greater numbers of CLSs in VAT and SAT, and a higher expression of COL6α3 in both compartments. Conclusions: Obesity in childhood may lead to increased COL6α3 gene expression and promote the activation of macrophage polarization, compromise the structural integrity of the ECM, and thus influence the development of inflammatory processes.

Autoimmune mechanisms and inflammation in obesity-associated type 2 diabetes, atherosclerosis, and non-alcoholic fatty liver disease

Obesity, characterized by the excessive accumulation of white adipose tissue, is a significant global health burden and a major risk factor for a range of diseases, including malignancies and metabolic disorders. Individuals with high visceral fat content are particularly susceptible to severe complications such as type 2 diabetes, cardiovascular diseases, and liver disorders. However, the pathogenesis of obesity-related metabolic diseases extends beyond simple adiposity. Chronic obesity triggers a prolonged inflammatory response, which leads to tissue fibrosis and sustained organ damage, contributing to multi-organ dysfunction. This review explores the autoimmune mechanisms and inflammatory pathways underlying obesity-induced type 2 diabetes, atherosclerosis, and non-alcoholic fatty liver disease, with an emphasis on their interrelated pathophysiology and the potential for therapeutic interventions.

Obesity-associated Inflammation and Alloimmunity

Obesity is a worldwide health problem with a rapidly rising incidence. In organ transplantation, increasing numbers of patients with obesity accumulate on waiting lists and undergo surgery. Obesity is in general conceptualized as a chronic inflammatory disease, potentially impacting alloimmune response and graft function. Here, we summarize our current understanding of cellular and molecular mechanisms that control obesity-associated adipose tissue inflammation and provide insights into mechanisms affecting transplant outcomes, emphasizing on the beneficial effects of weight loss on alloimmune responses.

Endothelial cell alterations in capillaries of adipose tissue from patients affected by lipedema

OBJECTIVE

This study aimed to evaluate adipose tissue of lipedema patients.

METHODS

Gluteo-femoral (affected area) and interscapular (nonaffected area) adipose tissue from 10 lean patients affected by lipedema stage 1 to 2 was studied and compared with tissue from 10 patients with obesity and 12 lean patients.

RESULTS

The main features were alterations of capillaries with wall thickening (p ≤ 0.0001), endothelial and pericyte hyperplasia (p = 0.03 and p = 0.004), hypodense areas in basal membrane, and endothelial degeneration with exfoliation of degenerated cells into the capillary lumen. Adipocytes were larger (hypertrophic) in affected (P ≤ 0.0001) and nonaffected (p = 0.0003) areas compared with those with obesity and who were lean (both p ≤ 0.0001). Frequently the cytoplasm of adipocytes contained massive deposition of calcium crystals as revealed by Von Kossa staining (p = 0.023) and electron microscopy. CD68 immunoreactive macrophages were more abundant in affected areas (p = 0.005), and their number was similar to that found in fat from patients with obesity (p = 0.17). Despite adipocyte hypertrophy and inflammation, lack of the healthy marker perilipin-1 and the presence of crown-like structures were only rarely seen, while they were quite frequent in patients with obesity.

CONCLUSIONS

Our data support the idea that cell alterations happen in the early stages of adipocyte development (endothelium/pericyte) in the adipose organ of women affected by lipedema.

Inhibition of DPP-4 Attenuates Endotoxemia-Induced NLRC4 Inflammasome and Inflammation in Visceral Adipose Tissue of Mice Fed a High-Fat Diet

Inflammasomes are protein complexes that trigger pro-inflammatory responses and promote many diseases, including adipose tissue dysfunction. Linagliptin (L), a DPP-4 inhibitor used for type 2 diabetes therapy, has putative anti-inflammatory effects. This work explores L effects on inflammasome regulation, inflammation, and adipose tissue dysfunction in obese mice. Male C57BL/6N mice were fed a normal chow (NC) diet, high-fat (HF) diet, or HF diet with L (HFL) for 15 weeks. Gene expression and histological examinations were performed on visceral (VAT) and subcutaneous (SAT) adipose tissue samples. Biomarkers were quantified on sera. Murine macrophages were utilized for in vitro analyses. L decreased HF-induced endotoxemia and circulating inflammatory indicators. Despite having no effect on body weight, L reduced VAT inflammation by decreasing endotoxemia-induced NLRC4 inflammasome, inflammation severity, and fat cell hypertrophy. Although SAT response differed from VAT, inflammation was slightly reduced in this tissue too. In vitro, L modulated inflammation by directly reducing the pro-inflammatory macrophage phenotype. In obesity, increased NLRC4 inflammasome expression links endotoxemia and VAT inflammation. L protected against endotoxemia, maybe by affecting gut permeability and VAT responses. The decreased polarization of macrophages toward a pro-inflammatory phenotype and the reduction in adipocyte hypertrophy are involved in the response to L.

Adipose Tissue Stromal Cells: Rheostats for Adipose Tissue Function and Metabolic Disease Risk

The transition from metabolically healthy obesity to the development of obesity-associated metabolic syndrome and cardiovascular disease is thought to be triggered by a loss in the functional integrity of adipose tissue. Although mature adipocytes are the primary functional units that carry out lipid partitioning in adipose tissue for the promotion of whole-body energy balance, they are supported by a heterogenous collection of nonadipocytes in the stroma. Research over the past couple of decades has expanded perspectives on the homeostatic and pathological roles of the nonadipocyte compartment. Adipose progenitors originate in the embryonic period and drive the developmental adipogenesis that establishes the set point of adiposity. A population of adipocyte progenitors reside in adult depots and serve an important homeostatic role as a reservoir to support adipocyte turnover. Adipocyte hypertrophy in obesity increases the rate of adipocyte death and the ability of progenitors to support this high rate of adipocyte turnover is important for the preservation of the lipid-buffering function of adipose tissue. Some evidence exists to suggest that impaired adipogenesis or a decline in progenitors capable of differentiation is a key event in the development of adipose dysfunction. The efficiency of macrophages to clear the debris and toxic lipids released from dead adipocytes lies at the fulcrum between preservation of adipose function and the progression toward chronic inflammation. Although macrophages in collaboration with other immune cells propagate the inflammation that underlies adipose dysfunction, there is now a greater appreciation for the diverse and unique roles of immune cells within adipose tissue.

Glycerol metabolism is activated in both palmitic acid-stimulated and adipose tissue macrophages from a murine model of cardiometabolic heart failure

Macrophages chronically exposed to saturated fatty acids, such as those encountered in adipose tissue, present a pro-inflammatory phenotype with a characteristic foamy morphology. This feature is caused by the excess uptake of circulating lipids, yielding large cytoplasmic lipid bodies formed by triacylglycerols and cholesteryl derivatives. Palmitic acid (PA) is a potent inflammatory inducer in macrophages after chronic exposure to this fatty acid. However, acute exposure to this fatty acid is unable to activate a pro-inflammatory phenotype, although it is sufficient to induce metabolic reprogramming including the formation of small lipid bodies. In the present study, we used an in vitro model of human monocyte-derived macrophages to unravel the early stages of metabolic reprogramming observed in macrophages exposed to PA. We observed that partial inhibition of the glycerol 3-phosphate shuttle is necessary for supplying glycerol 3-phosphate for triacylglycerol biosynthesis. Furthermore, we characterized an alternative pathway to increase the concentration of glycerol 3-phosphate involving an aquaporin and glycerol kinase. Our results suggested that early lipid bodies biogenesis rises as a response mechanism to buffer excessive PA without inducing a pro-inflammatory program. Additionally, we observed that macrophages chronically exposed to PA eventually upregulate the production of inflammatory cytokines. Finally, our in vitro observations were confirmed in adipose tissue macrophages derived from a preclinical mouse model of cardiometabolic heart failure with preserved ejection fraction characterized by heightened adiposity and inflammation. KEY POINTS: The glycerol 3-phosphate shuttle is partially inhibited in palmitic acid-activated macrophages. Aquaporin 3 expression is upregulated in macrophages exposed to palmitic acid and in adipose tissue macrophages from a murine model of cardiometabolic heart failure. Aquaporin 3 participates in the biosynthesis of triacylglycerols by supplying extracellular glycerol.

Macrophage SUCLA2 coupled glutaminolysis manipulates obesity through AMPK

Obesity is regarded as a chronic inflammatory disease involving adipose tissue macrophages (ATM), but whether immunometabolic reprogramming of ATM affects obesity remains unclarified. Here we show that in ATM glutaminolysis is the fundamental metabolic flux providing energy and substrate, bridging with AMP-activated protein kinase (AMPK) activity, succinate-induced interleukin-1β (IL-1β) production, and obesity. Abrogation of AMPKα in myeloid cells promotes proinflammatory ATM, impairs thermogenesis and energy expenditure, and aggravates obesity in mice fed with high-fat diet (HFD). Conversely, IL-1β neutralization or myeloid IL-1β abrogation prevents obesity caused by AMPKα deficiency. Mechanistically, ATP generated from glutaminolysis suppresses AMPK to decrease phosphorylation of the β subunit of succinyl-CoA synthetase (SUCLA2), thereby resulting in the activation of succinyl-CoA synthetase and the overproduction of succinate and IL-1β; by contrast, siRNA-mediated SUCLA2 knockdown reduces obesity induced by HFD in mice. Lastly, phosphorylated SUCLA2 in ATM correlates negatively with obesity in humans. Our results thus implicate a glutaminolysis/AMPK/SUCLA2/IL-1β axis of inflammation and obesity regulation in ATM.

Vitamin D Enhancement of Adipose Biology: Implications on Obesity-Associated Cardiometabolic Diseases

Vitamin D is activated into 1α,25(OH)2D through two hydroxylation steps that are primarily catalyzed by 25-hydroxylase in the liver and 1α-hydroxylase in the kidneys. The active form of vitamin D regulates myriads of cellular functions through its nuclear receptor, vitamin D receptor (VDR). Vitamin D metabolizing enzymes and VDR are expressed in adipose tissues and vitamin D regulates multiple aspects of adipose biology including the recruitment and differentiation of adipose stem cells into adipocytes and metabolic, endocrine, and immune properties. Obesity is associated with low vitamin D status, which is thought to be explained by its sequestration in large mass of adipose tissues as well as dysregulated vitamin D metabolism. Low vitamin D status in obesity may negatively impact adipose biology leading to adipose tissue dysfunctions, the major pathological factors for cardiometabolic diseases in obesity. In this review, the current understanding of vitamin D metabolism and its molecular mechanisms of actions, focusing on vitamin D-VDR regulation of adipose biology with their implications on obesity-associated diseases, is discussed. Whether improving vitamin D status leads to reductions in adiposity and risks for cardiometabolic diseases is also discussed.

Non-canonical lysosomal lipolysis drives mobilization of adipose tissue energy stores with fasting

Physiological adaptations to fasting enable humans to survive for prolonged periods without food and involve molecular pathways that may drive life-prolonging effects of dietary restriction in model organisms. Mobilization of fatty acids and glycerol from adipocyte lipid stores by canonical neutral lipases, including the rate limiting adipose triglyceride lipase (Pnpla2/ATGL), is critical to the adaptive fasting response. Here we discovered an alternative mechanism of lipolysis in adipocytes involving a lysosomal program. We functionally tested lysosomal lipolysis with pharmacological and genetic approaches in mice and in murine and human adipocyte and adipose tissue explant culture, establishing dependency on lysosomal acid lipase (LIPA/LAL) and the microphthalmia/transcription factor E (MiT/TFE) family. Our study establishes a model whereby the canonical pathway is critical for rapid lipolytic responses to adrenergic stimuli operative in the acute stage of fasting, while the alternative lysosomal pathway dominates with prolonged fasting.

Deciphering the Role of CD36 in Gestational Diabetes Mellitus: Linking Fatty Acid Metabolism and Inflammation in Disease Pathogenesis

Gestational diabetes mellitus (GDM) is one of the most common pregnancy complications which exerts detrimental effects on mothers and children. Emerging evidence has pointed to the important role of the fatty acid transporter protein CD36 in the pathogenesis of GDM. As a heavily glycosylated transmembrane protein, CD36 is widely expressed in diverse cell types, including placental trophoblasts, monocytes/macrophages, adipocytes, and pancreatic cells et al. CD36 plays a key role in lipid metabolism and signal transduction in the pathophysiological mechanism of GDM. The modified expression and functionality of CD36 may contribute to inflammation and oxidative stress in maternal tissues, interfere with insulin signaling, and subsequently influence maternal insulin sensitivity and fetal growth, increasing the risk for GDM. This review provides an overview of the current knowledge regarding the expression and function of CD36 in various tissues throughout pregnancy and explores how CD36 dysregulation can activate inflammatory pathways, worsen insulin resistance, and disrupt lipid metabolism, thereby complicating the necessary metabolic adjustments during pregnancy. Furthermore, the review delves into emerging therapeutic approaches targeting CD36 signaling to alleviate the impacts of GDM. Understanding the involvement of CD36 in GDM could yield crucial insights into its mechanisms and potential interventions for enhancing maternal and fetal health outcomes.

Overweight-Related Hypertension in Middle-Aged Men Is Linked to Elevated Leptin, TNF-α, IL-6, Cholesterol, and Reduced Testosterone

BACKGROUND/OBJECTIVES

One of the major causes of hypertension (HT) is the transition of normal weight (NW) status to overweight (OW) status and obesity in a population, which leads to cardiovascular disease (CVD) and other disorders. A variety of factors/variables are involved in the development of HT and OW-related hypertension (OHT). However, we planned to investigate the pathophysiological role of serum leptin (Lep), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), total cholesterol (TC) and serum testosterone (ST) in OHT in middle-aged men.

METHODS

We consulted three groups of middle-aged men (age: 51-60 years)-an HT group (n: 97, high normal weight (HNW), body mass index (BMI): 23-24.9 kg/m2); an OHT group (n: 97, high overweight (HOW), BMI: 28-29.9 kg/m2) and a normal control group (NC, n: 98, HNW)-to investigate the variations in and correlations of Lep, IL-6, TNF-α, ST, TC and other variables.

RESULTS

Significant variations were obtained for the comparisons of TNF-α, Lep, ST and TC for the patient groups. OHT vs. NC showed a significant difference for ST. OHT vs. NC and OHT vs. HT had significant variations for IL-6. Significant changes were obtained for the serum levels of TNF-α, Lep, IL-6, ST and TC among groups. Significant and positive linear associations were obtained for TNF-α, Lep, TC and IL-6. Significant and negative linear associations were found for ST plotted against Lep, TNF-α and IL-6.

CONCLUSIONS

The current report provides pathophysiological evidence of the interactive role of serum Lep, TNF-α, ST, TC and IL-6 in middle-aged men with HT and OHT. We suggest that the changes we noted in the present study would be helpful for further BMI-based studies in various subcategories of NW, OW and obese subjects with/without HT.

Diet-induced impairment of skeletal muscle and adipose tissue metabolic homeostasis and its prevention by probiotic administration

Western dietary pattern is one of the main contributors to the increased risk of obesity and chronic diseases, through oxidative stress and inflammation, that are the two key mechanisms targeting metabolic organs, such as skeletal muscle and adipose tissue. The chronic exposure to high levels of dietary fatty acids can increase the amount of intramyocellular lipids in skeletal muscle, altering glucose homeostasis and contributing to a reduction in mitochondrial oxidative capacity. Probiotic administration is a promising approach as preventive strategy to attenuate metabolic damage induced by Western diet. Here, we investigated the beneficial effect of Limosillactobacillus reuteri DSM 17938 on the inflammatory state and oxidative balance in the skeletal muscle and adipose tissue of adult rats fed a western diet for 8 weeks, focusing on the role of skeletal muscle mitochondria. Limosillactobacillus reuteri DSM 17938 administration protected the skeletal muscle from mitochondrial dysfunction and oxidative stress, preventing the establishment of inflammation and insulin resistance. Interestingly, a further beneficial effect of the probiotic was exerted on body composition, favoring the deposition of protein mass and preventing adipose tissue hypertrophy and inflammation. These results open the possibility for the use of this probiotic in therapeutic approaches for nutrition-related diseases.

Exercise-induced anxiety impairs local and systemic inflammatory response and glucose metabolism in C57BL/6J mice

Introduction

The complex physiological and psychological responses to regular exercise are yet to be fully elucidated. Exercise strongly modulates the immune system, inducing a plethora of dynamic responses involving the innate immune cell function and inflammatory processes that contribute to both potential health benefits and harmful side effects. Indeed, the relationship between physical exercise, stress, immunity, and metabolism serves as a paramount model of neuroimmunoendocrine interaction. Thus, the objective of this study was to conduct a comprehensive analysis of both systemic and local immunophysiological responses together with behavioral responses to a protocol of anxiety-inducing exercise.

Material and methods

C57BL/6J mice were randomly allocated into sedentary or exercised groups, where the anxiety-inducing exercise protocol was based on a 14-day consecutive program of swimming in water at 38 °C. Anxiety-like behavior was corroborated through the elevated plus maze test. Systemic biomarkers of the stress response were assessed using ELISA technique and the expression of systemic inflammatory cytokines with Bio-Plex system. Phagocytic/microbicide activity, the expression of M1/M2 phenotype markers (CD11c, iNOS, CD206, ARG-1) and cytokines of the inflammatory response (MCP-1, IL-8, IL-6, TNF-α, TGF-β, IL-10) of peritoneal macrophages were determined via flow cytometry. Adipose tissue macrophage infiltration was studied through fluorescence immunohistochemistry.

Results

Anxiety-like behavior, elevated circulating glucose concentrations, systemic stress and inflammatory responses, together with increased oxidative stress and inflammatory profile of peritoneal macrophages, and macrophage infiltration in white adipose tissue were observed in exercised animals.

Conclusions

A protocol of exercise that induces anxiety is associated with a neuroimmunoendocrine dysregulation affecting the feedback between the inflammatory and the stress responses, together with detrimental metabolic effects in glucose modulation. Systemic inflammatory alterations are accompanied by detrimental inflammatory responses in tissue macrophage populations. Altogether, these results show that exercise associated with anxiety, stress, pro-inflammatory responses, and hyperglycaemia represents a model of 'dangerous exercise'.

How obesity affects adipocyte turnover

Cellular turnover is fundamental for tissue homeostasis and integrity. Adipocyte turnover, accounting for 4% of the total cellular mass turnover in humans, is essential for adipose tissue homeostasis during metabolic stress. In obesity, an altered adipose tissue microenvironment promotes adipocyte death. To clear dead adipocytes, macrophages are recruited and form a distinctive structure known as crown-like structure; subsequently, new adipocytes are generated from adipose stem and progenitor cells in the adipogenic niche to replace dead adipocytes. Accumulating evidence indicates that adipocyte death, clearance, and adipogenesis are sophisticatedly orchestrated during adipocyte turnover. In this Review, we summarize our current understandings of each step in adipocyte turnover, discussing its key players and regulatory mechanisms.

Targeting IRE1α improves insulin sensitivity and thermogenesis and suppresses metabolically active adipose tissue macrophages in male obese mice

Overnutrition engenders the expansion of adipose tissue and the accumulation of immune cells, in particular, macrophages, in the adipose tissue, leading to chronic low-grade inflammation and insulin resistance. In obesity, several proinflammatory subpopulations of adipose tissue macrophages (ATMs) identified hitherto include the conventional "M1-like" CD11C-expressing ATM and the newly discovered metabolically activated CD9-expressing ATM; however, the relationship among ATM subpopulations is unclear. The ER stress sensor inositol-requiring enzyme 1α (IRE1α) is activated in the adipocytes and immune cells under obesity. It is unknown whether targeting IRE1α is capable of reversing insulin resistance and obesity and modulating the metabolically activated ATMs. We report that pharmacological inhibition of IRE1α RNase significantly ameliorates insulin resistance and glucose intolerance in male mice with diet-induced obesity. IRE1α inhibition also increases thermogenesis and energy expenditure, and hence protects against high fat diet-induced obesity. Our study shows that the "M1-like" CD11c+ ATMs are largely overlapping with but yet non-identical to CD9+ ATMs in obese white adipose tissue. Notably, IRE1α inhibition diminishes the accumulation of obesity-induced metabolically activated ATMs and "M1-like" ATMs, resulting in the curtailment of adipose inflammation and ensuing reactivation of thermogenesis, without augmentation of the alternatively activated M2 macrophage population. Our findings suggest the potential of targeting IRE1α for the therapeutic treatment of insulin resistance and obesity.

Sarcopenia and cachexia: molecular mechanisms and therapeutic interventions

Sarcopenia is defined as a muscle-wasting syndrome that occurs with accelerated aging, while cachexia is a severe wasting syndrome associated with conditions such as cancer and immunodeficiency disorders, which cannot be fully addressed through conventional nutritional supplementation. Sarcopenia can be considered a component of cachexia, with the bidirectional interplay between adipose tissue and skeletal muscle potentially serving as a molecular mechanism for both conditions. However, the underlying mechanisms differ. Recognizing the interplay and distinctions between these disorders is essential for advancing both basic and translational research in this area, enhancing diagnostic accuracy and ultimately achieving effective therapeutic solutions for affected patients. This review discusses the muscle microenvironment's changes contributing to these conditions, recent therapeutic approaches like lifestyle modifications, small molecules, and nutritional interventions, and emerging strategies such as gene editing, stem cell therapy, and gut microbiome modulation. We also address the challenges and opportunities of multimodal interventions, aiming to provide insights into the pathogenesis and molecular mechanisms of sarcopenia and cachexia, ultimately aiding in innovative strategy development and improved treatments.

Divergent roles of RIPK3 and MLKL in high-fat diet-induced obesity and MAFLD in mice

Cell death frequently occurs in the pathogenesis of obesity and metabolic dysfunction-associated fatty liver disease (MAFLD). However, the exact contribution of core cell death machinery to disease manifestations remains ill-defined. Here, we show via the direct comparison of mice genetically deficient in the essential necroptotic regulators, receptor-interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like (MLKL), as well as mice lacking apoptotic caspase-8 in myeloid cells combined with RIPK3 loss, that RIPK3/caspase-8 signaling regulates macrophage inflammatory responses and drives adipose tissue inflammation and MAFLD upon high-fat diet feeding. In contrast, MLKL, divergent to RIPK3, contributes to both obesity and MAFLD in a manner largely independent of inflammation. We also uncover that MLKL regulates the expression of molecules involved in lipid uptake, transport, and metabolism, and congruent with this, we discover a shift in the hepatic lipidome upon MLKL deletion. Collectively, these findings highlight MLKL as an attractive therapeutic target to combat the growing obesity pandemic and metabolic disease.

Effects of duration of high-fat diet on adipocyte hyperplasia in rat epididymis

BACKGROUND

High-fat diet (HFD) contributes to obesity and enhances the expression of mature adipocyte markers. However, the effect of HFD on adipocyte hyperplasia remains controversial. This may be due to variations in the duration of HFD. This study aimed to investigate the effects of different durations of HFD on adipocyte hyperplasia and the expression of mature adipocyte-related markers in obese rats.

METHODS

We divided 32 Sprague-Dawley rats into four groups: B (standard diet control), H1 (HFD for four weeks), H2 (HFD for eight weeks), and H3 (HFD for 12 weeks). We evaluated the morphological changes in epididymal fat cells, measured serum inflammatory markers using enzyme-linked immunosorbent assay (ELISA) kits, and quantified adipocyte hyperplasia and maturation markers using western blotting.

RESULTS

We observed progressive increases in body weight, epididymal fat weight, serum leptin, TNF-α, IL-6, irisin, PPARγ, adiponectin, and FNDC5 protein expression over 8 weeks of HFD. 12 weeks of HFD intervention resulted in significant decreases in irisin, PPARγ, adiponectin, and FNDC5. Concurrently, the expression of perilipin A and ATGL declined with prolonged HFD.

CONCLUSIONS

Our results suggest that the duration of HFD significantly affects adipocyte ability to undergo hyperplasia in the epididymis of obese rats. Specifically, 4 weeks of HFD did not change the capacity for adipocyte hyperplasia, while 8 weeks of the diet enhanced this capacity. Interestingly, a longer diet duration (12 weeks) led to a decrease in adipocyte hyperplasia.

Crosstalk between pancreatic cancer and adipose tissue: Molecular mechanisms and therapeutic implications

The incidence rate of pancreatic cancer, a fatal illness with a meager 5-year survival rate, has been on the rise in recent times. When individuals accumulate excessive amounts of adipose tissue, the adipose organ becomes dysfunctional due to alterations in the adipose tissue microenvironment associated with inflammation and metabolism. This phenomenon may potentially contribute to the aberrant accumulation of fat that initiates pancreatic carcinogenesis, thereby influencing the disease's progression, resistance to treatment, and metastasis. This review presents a summary of the impact of pancreatic steatosis, visceral fat, cancer-associated adipocytes and lipid diets on the advancement of pancreatic cancer, as well as the reciprocal effects of pancreatic cancer on adipose tissue. Understanding the molecular mechanisms underlying the relationship between dysfunctional adipose tissue and pancreatic cancer better may lead to the discovery of new therapeutic targets for the disease's prevention and individualized treatment. This is especially important given the rising global incidence of obesity, which will improve the pancreatic cancer treatment options that are currently insufficient.

Remodeling of the Intracardiac Ganglia During the Development of Cardiovascular Autonomic Dysfunction in Type 2 Diabetes: Molecular Mechanisms and Therapeutics

Type 2 diabetes mellitus (T2DM) is one of the most significant health issues worldwide, with associated healthcare costs estimated to surpass USD 1054 billion by 2045. The leading cause of death in T2DM patients is the development of cardiovascular disease (CVD). In the early stages of T2DM, patients develop cardiovascular autonomic dysfunction due to the withdrawal of cardiac parasympathetic activity. Diminished cardiac parasympathetic tone can lead to cardiac arrhythmia-related sudden cardiac death, which accounts for 50% of CVD-related deaths in T2DM patients. Regulation of cardiovascular parasympathetic activity is integrated by neural circuitry at multiple levels including afferent, central, and efferent components. Efferent control of cardiac parasympathetic autonomic tone is mediated through the activity of preganglionic parasympathetic neurons located in the cardiac extensions of the vagus nerve that signals to postganglionic parasympathetic neurons located in the intracardiac ganglia (ICG) on the heart. Postganglionic parasympathetic neurons exert local control on the heart, independent of higher brain centers, through the release of neurotransmitters, such as acetylcholine. Structural and functional alterations in cardiac parasympathetic postganglionic neurons contribute to the withdrawal of cardiac parasympathetic tone, resulting in arrhythmogenesis and sudden cardiac death. This review provides an overview of the remodeling of parasympathetic postganglionic neurons in the ICG, and potential mechanisms contributing to the withdrawal of cardiac parasympathetic tone, ventricular arrhythmogenesis, and sudden cardiac death in T2DM. Improving cardiac parasympathetic tone could be a therapeutic avenue to reduce malignant ventricular arrhythmia and sudden cardiac death, increasing both the lifespan and improving quality of life of T2DM patients.

Mechanisms by which obesity regulates inflammation and anti-tumor immunity in cancer

Obesity is associated with an increased risk for 13 different cancers. The increased risk for cancer in obesity is mediated by obesity-associated changes in the immune system. Obesity has distinct effects on different types of inflammation that are tied to tumorigenesis. For example, obesity promotes chronic inflammation in adipose tissue that is tumor-promoting in peripheral tissues. Conversely, obesity inhibits acute inflammation that rejects tumors. Obesity therefore promotes cancer by differentially regulating chronic versus acute inflammation. Given that obesity is chronic, the initial inflammation in adipose tissue will lead to systemic inflammation that could induce compensatory anti-inflammatory reactions in peripheral tissues to suppress chronic inflammation. The overall effect of obesity in peripheral tissues is therefore dependent on the duration and severity of obesity. Adipose tissue is a complex tissue that is composed of many cell types in addition to adipocytes. Further, adipose tissue cellularity is different at different anatomical sites throughout the body. Consequently, the sensitivity of adipose tissue to obesity is dependent on the anatomical location of the adipose depot. For example, obesity induces more inflammation in visceral than subcutaneous adipose tissue. Based on these studies, the mechanisms by which obesity promotes tumorigenesis are multifactorial and immune cell type-specific. The objective of our paper is to discuss the cellular mechanisms by which obesity promotes tumorigenesis by regulating distinct types of inflammation in adipose tissue and the tumor microenvironment.

Estrogen: the forgotten player in metaflammation

Metaflammation is low-grade inflammation triggered by chronic metabolic imbalance and caused by dysregulated metabolites in metabolic inflammatory syndrome (MIS), which includes four diseases: obesity, type 2 diabetes mellitus (T2DM), atherosclerosis (AS), and nonalcoholic fatty liver diseases (NAFLD, recently proposed to be replaced by metabolic dysfunction-associated steatotic liver disease, MASLD). These diseases exhibit apparent sex dimorphism as regards MIS. Estrogen not only plays a crucial role in gender differences in adults but also possesses an anti-inflammatory effect on many metabolic diseases. In this study, we present a prediction of the differential proteins and signal transduction of estrogen in MIS through network pharmacology and review the validated studies on obesity, T2DM, AS, and NAFLD. Subsequently, we compared them to obtain valuable targets, identify current gaps, and provide perspectives for future research on the mechanisms of estrogen in metaflammation.

Two-Pronged Attack: Dual Activation of Fat Reduction Using Near-Infrared-Responsive Nanosandwich for Targeted Anti-Obesity Treatment

Excessive fat accumulation and chronic inflammation are two typical characteristics of obesity. AMP-activated protein kinase (AMPK), a master regulator of energy metabolism, is involved in adipogenesis, lipogenesis, and inflammation modulation in adipose tissue (AT). Thus, effective lipid reduction and anti-inflammation through AMPK regulation play vital roles in treating obesity. Herein, an anti-obesity nanosandwich is fabricated through attaching polymetformin (PolyMet) onto photothermal agent black phosphorus nanosheets (BP). PolyMet activates AMPK to inhibit adipogenesis, promote browning, and mitigate AT inflammation by decreasing macrophage infiltration, repolarizing macrophage phenotype, and downregulating pro-inflammatory cytokines. Additionally, BP induces lipolysis and apoptosis of adipocytes and macrophages through a photothermal effect. By further functionalization using hyaluronic acid (HA) and MMP2 substrate-linking P3 peptide-modified HA (P3-HA), an enhanced anti-obesity effect is obtained by dual-targeting of P3 and HA, and HA-mediated CD44 poly-clustering after MMP2 cleavage. Upon laser irradiation, the designed nanosandwich (P3-HA/PM@BP) effectively inhibits obesity development in obese mice, increases M2/M1 ratio in AT, reduces the serum levels of cholesterol/triglyceride and improves insulin sensitivity, exhibiting promising research potential to facilitate the clinical development of modern anti-obesity therapies.

Histologic Characterization of Tumor-Adjacent Mammary Adipose Tissue in Normal-Weight and Overweight/Obese Patients with Triple-Negative Breast Cancer

Background: Obesity is a risk factor of several types of cancer, including breast cancer. In this study, we aimed to histologically characterize the adipose tissue of the tumor microenvironment (TME) of triple-negative breast cancer (TNBC) in overweight/obese versus normal-weight patients. Methods: TNBC tissue sections from normal-weight (BMI<25) and overweight/obese patients (BMI≥25) were stained with antibodies against CD68, CD163, CD31, CD34, and vimentin. At the invasive tumor front, positive cells were counted in tumor adjacent adipose tissue (AT) and within cancer tissue (CT). Further, the size of the tumor-adjacent and distant mammary adipocytes was determined in perilipin stained sections. Expression of ANGPTL4, CD36 and FABP4, proteins involved in fatty acid metabolism, was analyzed in marginal tumor cells using an immune reactive score. Results: Overweight/obese TNBC patients had significantly larger adipocytes, higher numbers of CD163+ macrophages (BMI<25: 2.80 vs. BMI≥25: 10.45; p = 0.011) and lower numbers of CD31+ (BMI<25: 4.20 vs. BMI≥25: 2.40; p = 0.018) and CD34+ (BMI<25: 14.60 vs. BMI≥25: 5.20; p = 0.045) cells as markers of angiogenesis in the AT as well as a higher frequency of cancer-associated-fibroblast-like cells in the AT and CT (BMI<25: 7.60 vs. BMI≥25: 25.39 in total; p = 0.001). Moreover, expression of CD36 (BMI<25: 2.15 vs. BMI≥25: 2.60; p = 0.041) and ANGPTL4 (BMI<25: 6.00 vs. BMI≥25: 9.80; p = 0.026) was elevated in the TNBC cells of overweight/obese patients. Conclusions: Our data suggest BMI-related changes in the TME of overweight/obese TNBC patients, including hypertrophied adipocytes, reduced vascularization, more M2-like macrophages and CAF-like cells, and an increase in the expression of fatty acid metabolizing proteins in marginal tumor cells, all contributing to a more tumor-promoting, immunosuppressive environment.

Walnut extract protects against hepatic inflammation and toxicity induced by a high-fat diet

A high-fat diet (HFD) is one of the main causes of obesity and metabolic diseases. The liver is particularly affected by HFD causing metabolic dysfunction associated with fatty liver disease. Therefore, different strategies are used to mitigate the negative effects of HFD. This study aimed to assess the protective effects of walnut extract against HFD-induced toxicity in mice. The mice were fed HFD and walnut extract alone or in combination. The walnut extract was analyzed for composition using high-performance liquid chromatography with a diode array detector (HPLC-DAD) and ultra-high-performance liquid chromatography with mass spectrometry (UHPLC-MS/MS). Serum lipid profile; liver histology; hepatic antioxidants such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), lipid peroxidation (TBARS), and reduced glutathione (GSH); inflammatory markers like IL-6 and TNF-α; and phospholipids were determined. Results showed that phenolic acids, epicatechin, catechin, benzaldehyde, and juglone were the main constituents in the extract. The HFD group showed increased hepatic fat accumulation as evidenced by biochemical and histopathological examinations compared to the control animals. The HFD group mice also showed increased body and cardiac weights, modified lipid profiles, decreased antioxidant status, and increased levels of hepatic inflammatory markers. The weights of the body and heart, lipid profiles, antioxidant contents (CAT, SOD, GSH-Px, TBARS, and GSH), and pro-inflammatory cytokines (IL-6 and TNF-α) were all normalized by consuming walnut extract. Similarly, the HFD group had significantly high amounts of hepatic lipase, phospholipid, and lysophospholipid levels, which were improved by walnut extract. In conclusion, walnut extract has been shown to play a unique role in promoting the recovery of liver damage caused by a high-fat diet.

PDIA3 defines a novel subset of adipose macrophages to exacerbate the development of obesity and metabolic disorders

Adipose tissue macrophages (ATMs) play important roles in maintaining adipose tissue homeostasis and orchestrating metabolic inflammation. Given the extensive functional heterogeneity and phenotypic plasticity of ATMs, identification of the authentically pathogenic ATM subpopulation under obese setting is thus necessitated. Herein, we performed single-nucleus RNA sequencing (snRNA-seq) and unraveled a unique maladaptive ATM subpopulation defined as ATF4hiPDIA3hiACSL4hiCCL2hi inflammatory and metabolically activated macrophages (iMAMs), in which PDIA3 is required for the maintenance of their migratory and pro-inflammatory properties. Mechanistically, ATF4 serves as a metabolic stress sensor to transcribe PDIA3, which then imposes a redox control on RhoA activity and strengthens the pro-inflammatory and migratory properties of iMAMs through RhoA-YAP signaling. Administration of Pdia3 small interfering RNA (siRNA)-loaded liposomes effectively repressed adipose inflammation and high-fat diet (HFD)-induced obesity. Together, our data support that strategies aimed at targeting iMAMs by suppressing PDIA3 expression or activity could be a viable approach against obesity and metabolic disorders in clinical settings.

Meflin/ISLR is a marker of adipose stem and progenitor cells in mice and humans that suppresses white adipose tissue remodeling and fibrosis

Identifying specific markers of adipose stem and progenitor cells (ASPCs) in vivo is crucial for understanding the biology of white adipose tissues (WAT). PDGFRα-positive perivascular stromal cells represent the best candidates for ASPCs. This cell lineage differentiates into myofibroblasts that contribute to the impairment of WAT function. However, ASPC marker protein(s) that are functionally crucial for maintaining WAT homeostasis are unknown. We previously identified Meflin as a marker of mesenchymal stem cells (MSCs) in bone marrow and tissue-resident perivascular fibroblasts in various tissues. We also demonstrated that Meflin maintains the undifferentiated status of MSCs/fibroblasts. Here, we show that Meflin is expressed in WAT ASPCs. A lineage-tracing experiment showed that Meflin+ ASPCs proliferate in the WAT of obese mice induced by a high-fat diet (HFD), while some of them differentiate into myofibroblasts or mature adipocytes. Meflin knockout mice fed an HFD exhibited a significant fibrotic response as well as increases in adipocyte cell size and the number of crown-like structures in WAT, accompanied by impaired glucose tolerance. These data suggested that Meflin expressed by ASPCs may have a role in reducing disease progression associated with WAT dysfunction.

Dynamic Roles and Expanding Diversity of Adipose Tissue Macrophages in Obesity

Adipose tissue macrophages (ATMs) are key regulators of adipose tissue (AT) inflammation and insulin resistance in obesity, and the traditional M1/M2 characterization of ATMs is inadequate for capturing their diversity in obese conditions. Single-cell transcriptomic profiling has revealed heterogeneity among ATMs that goes beyond the old paradigm and identified new subsets with unique functions. Furthermore, explorations of their developmental origins suggest that multiple differentiation pathways contribute to ATM variety. These advances raise concerns about how to define ATM functions, how they are regulated, and how they orchestrate changes in AT. This review provides an overview of the current understanding of ATMs and their updated categorization in both mice and humans during obesity. Additionally, diverse ATM functions and contributions in the context of obesity are discussed. Finally, potential strategies for targeting ATM functions as therapeutic interventions for obesity-induced metabolic diseases are addressed.

Fiery Connections: Macrophage-Mediated Inflammation, the Journey from Obesity to Type 2 Diabetes Mellitus and Diabetic Kidney Disease

The high prevalence of diabetes mellitus (DM) poses a significant public health challenge, with diabetic kidney disease (DKD) as one of its most serious consequences. It has become increasingly clear that type 2 DM (T2D) and the complications of DKD are not purely metabolic disorders. This review outlines emerging evidence related to the step-by-step contribution of macrophages to the development and progression of DKD in individuals who specifically develop T2D as a result of obesity. The macrophage is a prominent inflammatory cell that contributes to obesity, where adipocyte hypertrophy leads to macrophage recruitment and eventually to the expansion of adipose tissue. The recruited macrophages secrete proinflammatory cytokines, which cause systemic inflammation, glucose dysregulation, and insulin sensitivity, ultimately contributing to the development of T2D. Under such pathological changes, the kidney is susceptible to elevated glucose and thereby activates signaling pathways that ultimately drive monocyte recruitment. In particular, the early recruitment of proinflammatory macrophages in the diabetic kidney produces inflammatory cytokines/chemokines that contribute to inflammation and tissue damage associated with DKD pathology. Macrophage activation and recruitment are crucial inciting factors that also persist as DKD progresses. Thus, targeting macrophage activation and function could be a promising therapeutic approach, potentially offering significant benefits for managing DKD at all stages of progression.

Hypoxia in Human Obesity: New Insights from Inflammation towards Insulin Resistance-A Narrative Review

Insulin resistance (IR), marked by reduced cellular responsiveness to insulin, and obesity, defined by the excessive accumulation of adipose tissue, are two intertwined conditions that significantly contribute to the global burden of cardiometabolic diseases. Adipose tissue, beyond merely storing triglycerides, acts as an active producer of biomolecules. In obesity, as adipose tissue undergoes hypertrophy, it becomes dysfunctional, altering the release of adipocyte-derived factors, known as adipokines. This dysfunction promotes low-grade chronic inflammation, exacerbates IR, and creates a hyperglycemic, proatherogenic, and prothrombotic environment. However, the fundamental cause of these phenomena remains unclear. This narrative review points to hypoxia as a critical trigger for the molecular changes associated with fat accumulation, particularly within visceral adipose tissue (VAT). The activation of hypoxia-inducible factor-1 (HIF-1), a transcription factor that regulates homeostatic responses to low oxygen levels, initiates a series of molecular events in VAT, leading to the aberrant release of adipokines, many of which are still unexplored, and potentially affecting peripheral insulin sensitivity. Recent discoveries have highlighted the role of hypoxia and miRNA-128 in regulating the insulin receptor in visceral adipocytes, contributing to their dysfunctional behavior, including impaired glucose uptake. Understanding the complex interplay between adipose tissue hypoxia, dysfunction, inflammation, and IR in obesity is essential for developing innovative, targeted therapeutic strategies.

Exploring the link between leptin levels and metabolic syndrome in elderly Indian patients: Implications for family medicine and primary care practices

Background

The metabolic syndrome (MetS), according to the Adult Treatment Panel III of the National Cholesterol Education Programme, is a collection of metabolic abnormalities that includes one, two, or all three of the following traits: obesity in the abdomen, dyslipidemia, hypertension, fasting blood sugar, or insulin resistance. This study's aim was to assess the relationship between fasting serum leptin and MetS in elderly adults with T2DM in the Northern Indian population.

Material and Methods

The following information was collected from all the participants: (1) anthropometric data, (2) biochemical data, and (3) a lifestyle questionnaire on sociodemographic data, dietary practices, smoking, and alcohol intake to identify their risk factors for diabetes mellitus, CVD, and hypertension.

Results

A total of 36 older participants (56.30%) had a history of hypertension, while 29 elderly participants (44.61%) had diabetes mellitus. A total of 32 elderly participants (49.2%) had MetS, and this group had higher serum leptin (P 0.003), body weight (P = 0.019), BMI (P 0.001), waist circumference (P 0.001), CRP (P = 0.021), insulin (P = 0.001), and HOMA-IR (P = 0.003) values as well as higher percentages of females (P = 0.001), and those with type 2 diabetes mellitus (P = 0.002) and hypertension (P = 0.039) than those in the non-MetS group.

Conclusion

In older persons with T2DM, our study discovered a favorable correlation between serum leptin and MetS. It can act as a standalone indicator of MetS, offering a way to spot populations at risk for associated consequences and enabling early intervention.

Cell life-or-death events in osteoporosis: All roads lead to mitochondrial dynamics

Mitochondria exhibit heterogeneous shapes and networks within and among cell types and tissues, also in normal or osteoporotic bone tissues with complex cell types. This dynamic characteristic is determined by the high plasticity provided by mitochondrial dynamics and is stemmed from responding to the survival and functional requirements of various bone cells in a specific microenvironments. In contrast, mitochondrial dysfunction, induced by dysregulation of mitochondrial dynamics, may act as a trigger of cell death signals, including common apoptosis and other forms of programmed cell death (PCD). These PCD processes consisting of tightly structured cascade gene expression events, can further influence the bone remodeling by facilitating the death of various bone cells. Mitochondrial dynamics, therefore, drive the bone cells to stand at the crossroads of life and death by integrating external signals and altering metabolism, shape, and signal-response properties of mitochondria. This implies that targeting mitochondrial dynamics displays significant potential in treatment of osteoporosis. Considerable effort has been made in osteoporosis to emphasize the parallel roles of mitochondria in regulating energy metabolism, calcium signal transduction, oxidative stress, inflammation, and cell death. However, the emerging field of mitochondrial dynamics-related PCD is not well understood. Herein, to bridge the gap, we outline the latest knowledge on mitochondrial dynamics regulating bone cell life or death during normal bone remodeling and osteoporosis.

Adipose tissue macrophage infiltration and hepatocyte stress increase GDF-15 throughout development of obesity to MASH

Plasma growth differentiation factor-15 (GDF-15) levels increase with obesity and metabolic dysfunction-associated steatotic liver disease (MASLD) but the underlying mechanism remains poorly defined. Using male mouse models of obesity and MASLD, and biopsies from carefully-characterized patients regarding obesity, type 2 diabetes (T2D) and MASLD status, we identify adipose tissue (AT) as the key source of GDF-15 at onset of obesity and T2D, followed by liver during the progression towards metabolic dysfunction-associated steatohepatitis (MASH). Obesity and T2D increase GDF15 expression in AT through the accumulation of macrophages, which are the main immune cells expressing GDF15. Inactivation of Gdf15 in macrophages reduces plasma GDF-15 concentrations and exacerbates obesity in mice. During MASH development, Gdf15 expression additionally increases in hepatocytes through stress-induced TFEB and DDIT3 signaling. Together, these results demonstrate a dual contribution of AT and liver to GDF-15 production in metabolic diseases and identify potential therapeutic targets to raise endogenous GDF-15 levels.

Lesson on obesity and anatomy of adipose tissue: new models of study in the era of clinical and translational research

Obesity is a serious global illness that is frequently associated with metabolic syndrome. Adipocytes are the typical cells of adipose organ, which is composed of at least two different tissues, white and brown adipose tissue. They functionally cooperate, interconverting each other under physiological conditions, but differ in their anatomy, physiology, and endocrine functions. Different cellular models have been proposed to study adipose tissue in vitro. They are also useful for elucidating the mechanisms that are responsible for a pathological condition, such as obesity, and for testing therapeutic strategies. Each cell model has its own characteristics, culture conditions, advantages and disadvantages. The choice of one model rather than another depends on the specific study the researcher is conducting. In recent decades, three-dimensional cultures, such as adipose spheroids, have become very attractive because they more closely resemble the phenotype of freshly isolated cells. The use of such models has developed in parallel with the evolution of translational research, an interdisciplinary branch of the biomedical field, which aims to learn a scientific translational approach to improve human health and longevity. The focus of the present review is on the growing body of data linking the use of new cell models and the spread of translational research. Also, we discuss the possibility, for the future, to employ new three-dimensional adipose tissue cell models to promote the transition from benchside to bedsite and vice versa, allowing translational research to become routine, with the final goal of obtaining clinical benefits in the prevention and treatment of obesity and related disorders.

BAFF neutralization impairs the autoantibody-mediated clearance of dead adipocytes and aggravates obesity-induced insulin resistance

B cell-activating factor (BAFF) is a critical TNF-family cytokine that regulates homeostasis and peripheral tolerance of B2 cells. BAFF overproduction promotes autoantibody generation and autoimmune diseases. During obesity, BAFF is predominantly produced by white adipose tissue (WAT), and IgG autoantibodies against adipocytes are identified in the WAT of obese humans. However, it remains to be determined if the autoantibodies formed during obesity affect WAT remodeling and systemic insulin resistance. Here, we show that IgG autoantibodies are generated in high-fat diet (HFD)-induced obese mice that bind to apoptotic adipocytes and promote their phagocytosis by macrophages. Next, using murine models of obesity in which the gonadal WAT undergoes remodeling, we found that BAFF neutralization depleted IgG autoantibodies, increased the number of dead adipocytes, and exacerbated WAT inflammation and insulin resistance. RNA sequencing of the stromal vascular fraction from the WAT revealed decreased expression of immunoglobulin light-chain and heavy-chain variable genes suggesting a decreased repertoire of B cells after BAFF neutralization. Further, the B cell activation and the phagocytosis pathways were impaired in the WAT of BAFF-neutralized mice. In vitro, plasma IgG fractions from BAFF-neutralized mice reduced the phagocytic clearance of apoptotic adipocytes. Altogether, our study suggests that IgG autoantibodies developed during obesity, at least in part, dampens exacerbated WAT inflammation and systemic insulin resistance.

Safety and Efficacy of Canakinumab for the Prevention and Control of Type 2 Diabetes Mellitus and Its Complications: A Systematic Review

Today, diabetes mellitus (DM) is one of the leading causes of morbidity and mortality globally.In this grim context, while our current armamentarium of anti-diabetic agents is vast and increasingly available, glycemic control in a significant proportion of these patients continues to remain sub-optimal.This necessitates the exploration of other potential cellular pathways and targets to effectively manage this notorious disease and its numerous complications. Inflammatory responses are thought to be implicated in the decline of pancreatic beta-cell function, with interleukin-1 beta (IL-1β) playing an important role in these pathways. Canakinumab, a human monoclonal anti-IL-1β antibody, operates by reducing inflammation, potentially safeguarding or enhancing pancreatic beta-cell function. This systematic review aims to study the safety and efficacy of canakinumab in the prevention and control of type 2 diabetes mellitus (T2DM) and its complications. This study was conducted in accordance with the PRISMA 2020 Guidelines. PubMed including MEDLINE, Google Scholar and Cochrane Library were used as information sources and randomized clinical trials and retrospective observational studies evaluating patients with T2DM or impaired glucose tolerance with/without complications receiving canakinumab, compared with placebo or standard therapy and reporting about glycemic indicators including hemoglobin A1C (HbA1C) or blood sugar levels (BSL) or insulin levels and/or inflammatory indicators including high-sensitivity C-reactive protein (hsCRP) or interleukin-6 (IL-6) were included. Non-randomized clinical trials, animal studies, review articles, case reports, case series, studies not in the English language and those evaluating type 1 DM were excluded. In total, 271 studies were identified to be included in this study. Subsequently, 27 were found to be duplicate records and were eliminated. Manual screening of title/abstract of 244 records was done which found 207 to be ineligible and 37 studies were shortlisted. These were retrieved and full-text screening was undertaken which resulted in the exclusion of 28 reports due to the following reasons: ineligible study design (17), studies evaluating type 1 DM (three), studies evaluating anakinra (one), trial being canceled (three) and duplicate studies (four). Subsequently, a total of nine studies were included in the final review. All studies were included post quality appraisal. We found that canakinumab had a modest but mostly non-significant effect on glycemic parameters including HbA1C, while having a consistently significant reduction in systemic inflammatory parameters like hsCRP and IL-6. Additionally, it was found to have a significant reduction in incident major adverse cardiovascular events (MACE). Canakinumab was also found to be safe and well-tolerated in all patient populations. Although canakinumab did not reduce incident T2DM, an exploration of alternative pathways and targets implicated in the pathogenesis of this disease process is warranted for the prevention and control of T2DM.

A Preliminary Study on Factors That Drive Patient Variability in Human Subcutaneous Adipose Tissues

Adipose tissue is a dynamic regulatory organ that has profound effects on the overall health of patients. Unfortunately, inconsistencies in human adipose tissues are extensive and multifactorial, including large variability in cellular sizes, lipid content, inflammation, extracellular matrix components, mechanics, and cytokines secreted. Given the high human variability, and since much of what is known about adipose tissue is from animal models, we sought to establish correlations and patterns between biological, mechanical, and epidemiological properties of human adipose tissues. To do this, twenty-six independent variables were cataloged for twenty patients, which included patient demographics and factors that drive health, obesity, and fibrosis. A factorial analysis for mixed data (FAMD) was used to analyze patterns in the dataset (with BMI > 25), and a correlation matrix was used to identify interactions between quantitative variables. Vascular endothelial growth factor A (VEGFA) and actin alpha 2, smooth muscle (ACTA2) gene expression were the highest loadings in the first two dimensions of the FAMD. The number of adipocytes was also a key driver of patient-related differences, where a decrease in the density of adipocytes was associated with aging. Aging was also correlated with a decrease in overall lipid percentage of subcutaneous tissue, with lipid deposition being favored extracellularly, an increase in transforming growth factor-β1 (TGFβ1), and an increase in M1 macrophage polarization. An important finding was that self-identified race contributed to variance between patients in this study, where Black patients had significantly lower gene expression levels of TGFβ1 and ACTA2. This finding supports the urgent need to account for patient ancestry in biomedical research to develop better therapeutic strategies for all patients. Another important finding was that TGFβ induced factor homeobox 1 (TGIF1), an understudied signaling molecule, which is highly correlated with leptin signaling, was correlated with metabolic inflammation. Furthermore, this study draws attention to what we define as "extracellular lipid droplets", which were consistently found in collagen-rich regions of the obese adipose tissues evaluated here. Reduced levels of TGIF1 were correlated with higher numbers of extracellular lipid droplets and an inability to suppress fibrotic changes in adipose tissue. Finally, this study indicated that M1 and M2 macrophage markers were correlated with each other and leptin in patients with a BMI > 25. This finding supports growing evidence that macrophage polarization in obesity involves a complex, interconnecting network system rather than a full switch in activation patterns from M2 to M1 with increasing body mass. Overall, this study reinforces key findings in animal studies and identifies important areas for future research, where human and animal studies are divergent. Understanding key drivers of human patient variability is required to unravel the complex metabolic health of unique patients.

Cellular Senescence and Extracellular Vesicles in the Pathogenesis and Treatment of Obesity-A Narrative Review

This narrative review explores the pathophysiology of obesity, cellular senescence, and exosome release. When exposed to excessive nutrients, adipocytes develop mitochondrial dysfunction and generate reactive oxygen species with DNA damage. This triggers adipocyte hypertrophy and hypoxia, inhibition of adiponectin secretion and adipogenesis, increased endoplasmic reticulum stress and maladaptive unfolded protein response, metaflammation, and polarization of macrophages. Such feed-forward cycles are not resolved by antioxidant systems, heat shock response pathways, or DNA repair mechanisms, resulting in transmissible cellular senescence via autocrine, paracrine, and endocrine signaling. Senescence can thus affect preadipocytes, mature adipocytes, tissue macrophages and lymphocytes, hepatocytes, vascular endothelium, pancreatic β cells, myocytes, hypothalamic nuclei, and renal podocytes. The senescence-associated secretory phenotype is closely related to visceral adipose tissue expansion and metaflammation; inhibition of SIRT-1, adiponectin, and autophagy; and increased release of exosomes, exosomal micro-RNAs, pro-inflammatory adipokines, and saturated free fatty acids. The resulting hypernefemia, insulin resistance, and diminished fatty acid β-oxidation lead to lipotoxicity and progressive obesity, metabolic syndrome, and physical and cognitive functional decline. Weight cycling is related to continuing immunosenescence and exposure to palmitate. Cellular senescence, exosome release, and the transmissible senescence-associated secretory phenotype contribute to obesity and metabolic syndrome. Targeted therapies have interrelated and synergistic effects on cellular senescence, obesity, and premature aging.

Inquiry of the Metabolic Traits in Relationship with Daily Magnesium Intake: Focus on Type 2 Diabetic Population

Magnesium (Mg), an essential nutrient with a wide area of physiological roles, stands as a cofactor in over 600 enzymatic reactions involved in the synthesis of proteins and nucleic acids, DNA repair, neuromuscular functions, neuronal transmission, cardiac rhythm regulation, and the modulation of metabolic pathways, as well as acting as a natural blocker for the calcium channels. Our objective was to highlight the most recent clinical data with respect to daily Mg intake (DMI) and metabolic traits, particularly type 2 diabetes mellitus (DM). This was a PubMed-based review of the English-language medical papers across different key terms of search; the time frame was from January 2019 until April 2024. We included (clinically relevant) original studies and excluded cases reports, series, reviews, editorials, opinion, experimental studies, and non-human data as well as studies that did not specifically assessed DMI and only provided assays of serum Mg, studies on patients diagnosed with type 1 or secondary DM. A total of 30 studies were included and we organized the key findings into several sections as follows. Studies investigating DMI in relationship with the adherence to local recommendations in diabetic subjects (n = 2, one transversal and another retrospective cohort; N = 2823) found that most of them had lower DMI. Deficient DMI was correlated with the risk of developing/having DM across five studies (n = 5, one prospective and four of cross-sectional design; N = 47,166). An inverse correlation between DMI and DM prevalence was identified, but these data are presented amid a rather heterogeneous spectrum. Four novel studies (N = 7279) analysed the relationship between DMI and DM control according to various methods (HbA1c, fasting and postprandial glycaemia, and insulin); the association may be linear in diabetic subjects only at certain levels of DMI; additionally, the multifactorial influence on HBA1c should take into consideration this dietary determinant, as well, but there are no homogenous results. Three studies concerning DMI and diabetic complications (one cross-sectional, one prospective, and another case-control study) in terms of retinopathy (n = 1, N = 3794) and nephropathy (n = 2, N = 4805) suggested a lower DMI was associated with a higher risk of such complications. Additionally, two other studies (one prospective and one retrospective cohort) focused on mortality (N = 6744), which, taking only certain mortality indicators into consideration, might be decreased in the subgroups with a higher DMI. Seven studies (N = 30,610) analysed the perspective of DMI in the general population with the endpoint of different features amid glucose profile, particularly, insulin resistance. Concerning HOMA-IR, there were three confirmatory studies and one non-confirmatory, while fasting plasma glucose was highlighted as inversely correlated with a DMI (n = 1). The highest level of evidence regarding Mg supplementation effects on glucose metabolism stands on seven randomised controlled trials (N = 350). However, the sample size was reduced (from 14 to 86 individuals per study, either diabetic or pre-diabetic) and outcomes were rather discordant. These clinical aspects are essential from a multidisciplinary perspective and further trials are mandatory to address the current areas of discordant results.

The Interplay between Obesity and Inflammation

Obesity is an important condition affecting the quality of life of numerous patients and increasing their associated risk for multiple diseases, including tumors and immune-mediated disorders. Inflammation appears to play a major role in the development of obesity and represents a central point for the activity of cellular and humoral components in the adipose tissue. Macrophages play a key role as the main cellular component of the adipose tissue regulating the chronic inflammation and modulating the secretion and differentiation of various pro- and anti-inflammatory cytokines. Inflammation also involves a series of signaling pathways that might represent the focus for new therapies and interventions. Weight loss is essential in decreasing cardiometabolic risks and the degree of associated inflammation; however, the latter can persist for long after the excess weight is lost, and can involve changes in macrophage phenotypes that can ensure the metabolic adjustment. A clear understanding of the pathophysiological processes in the adipose tissue and the interplay between obesity and chronic inflammation can lead to a better understanding of the development of comorbidities and may ensure future targets for the treatment of obesity.

Breast volume in non-obese females is related to breast adipose cell hypertrophy, inflammation, and COX2 expression

BACKGROUND

Breast hypertrophy seems to be a risk factor for breast cancer and the amount and characteristics of breast adipose tissue may play important roles. The main aim of this study was to investigate associations between breast volume in normal weight women and hypertrophic adipose tissue and inflammation.

METHODS

Fifteen non-obese women undergoing breast reduction surgery were examined. Breast volume was measured with plastic cups and surgery was indicated if the breast was 800 ml or larger according to Swedish guidelines. We isolated adipose cells from the breasts and ambient subcutaneous tissue to measure cell size, cell inflammation and other known markers of risk of developing breast cancer including COX2 gene activation and MAPK, a cell proliferation regulator.

RESULTS

Breast adipose cell size was characterized by cell hypertrophy and closely related to breast volume. The breast adipose cells were also characterized by being pro-inflammatory with increased IL-6, IL-8, IL-1β, CCL-2, TNF-a and an increased marker of cell senescence GLB1/β-galactosidase, commonly increased in hypertrophic adipose tissue. The prostaglandin synthetic marker COX2 was also increased in the hypertrophic cells and COX2 has previously been shown to be an important marker of risk of developing breast cancer. Interestingly, the phosphorylation of the proliferation marker MAPK was also increased in the hypertrophic adipose cells.

CONCLUSION

Taken together, these findings show that increased breast volume in non-obese women is associated with adipose cell hypertrophy and dysfunction and characterized by increased inflammation and other markers of increased risk for developing breast cancer.

TRIAL REGISTRATION

Projektdatabasen FoU i VGR, project number: 249191 (https://www.researchweb.org/is/vgr/project/249191).