Maria Joao Pereira

Context: Obesity-associated adipose tissue dysfunction is characterized by extracellular matrix (ECM) remodeling and fibrosis, where collagen VI and its bioactive cleavage peptide endotrophin have been implicated as key mediators. Objective: Characterize collagen VI alpha-3 (COL6A3) depot-specific expression in obesity and determine whether endotrophin impairs adipocyte metabolism and insulin responsiveness. Design, Setting, and Participants: COL6A3 expression was examined in paired subcutaneous (SAT) and omental adipose tissue (OAT) from 60 individuals spanning a broad Body-Mass-Index (BMI) range. Plasma endotrophin was measured in a subset of the cohort (n=42). Endotrophin effects were assessed in adipose explants, primary human and SGBS adipocytes. Main outcome me: asures. Depot-specific COL6A3 expression relative to BMI and endotrophin's effects on adipose tissue gene expression, GLUT4 levels, and adipocyte glucose uptake rate. Results: COL6A3 expression was associated with adiposity only in SAT. BMI remained an independent predictor after adjustment for age, sex, and metabolic covariates. COL6A3 co-expression patterns were positively associated with ECM remodeling and inflammation genes in both depots, while inverse associations with lipid metabolism and insulin signaling genes were specific to SAT. Circulating endotrophin levels were associated with fat mass percentage and triglyceride-to-HDL-cholesterol ratio, but not with adipose tissue COL6A3 expression. Endotrophin treatment reduced expression of PPARγ, SLC2A4 (GLUT4), and NR3C1, decreased GLUT4 protein, and impaired adipocyte insulin-stimulated glucose uptake rate without affecting AKT phosphorylation. Endotrophin reduced PPARγ, DGAT2, and SLC2A4 expression in differentiating SGBS adipocytes. Glucocorticoids upregulated COL6A3 in both depots. Conclusions: These findings implicate COL6A3-associated ECM remodelling and endotrophin in adipose dysfunction and impaired adipocyte insulin responsiveness in obesity.

Background: CD248 is a transmembrane glycoprotein implicated in fibrosis, hypoxia, and insulin resistance, but its role in human adipose tissue remains incompletely understood. Because glucocorticoids regulate these processes, we investigated whether CD248 is glucocorticoid responsive and characterized its expression across adipose depots and sexes in obesity. Methods: CD248 expression was assessed in adipose tissue obtained by needle biopsy (75 male/114 female, BMI: 20.1–47.9 kg/m ² ) and surgical sampling (24 male/39 female, BMI: 20.0–54.4 kg/m ² ) from individuals without type 2 diabetes, and in an additional cohort with type 2 diabetes (21 male/33 female, BMI: 22.4–42.4 kg/m ² ). Adipose tissue, isolated adipocytes and stromal vascular fraction were exposed to cortisol and dexamethasone. Circulating CD248 was analyzed in 44,545 participants from the UK Biobank Pharma Proteomics Project. Results: CD248 expression was higher in subcutaneous adipose tissue in obesity at mRNA (86%) and protein (2-fold) levels, with BMI as the strongest independent predictor. Expression did not differ between individuals with and without type 2 diabetes. Depot-specific differences were identified, with lower CD248 expression in omental adipose tissue than subcutaneous adipose tissue and opposing BMI associations. Sex-specific differences were observed at the protein level, with higher CD248 abundance in females with obesity. Transcriptomic analysis identified remodelling-related pathways in subcutaneous adipose tissue and metabolic pathways in omental adipose tissue. Dexamethasone and cortisol increased CD248 gene expression, and dexamethasone increased CD248 unglycosylated protein in adipocytes. Circulating CD248 increased with BMI and was higher in females with obesity, mirroring adipose tissue protein. Conclusion: Our findings identify CD248 as a glucocorticoid-responsive and depot-specific marker associated with adiposity and metabolic disturbances, suggesting a potential role in obesity-related adipose tissue dysfunction.

Aim: Men have a higher risk to develop type 2 diabetes (T2D) than women. The aim of this study was to investigate if there are sex differences in counter-regulatory hormone dynamics that might affect insulin resistance and hence propensity for T2D. Further, we addressed the roles of sex hormones, menopausal status and metabolic phenotypes for such sex differences. Methods: 22 men (7 T2D, BMI 28.8 kg/m2) and 28 women (16 postmenopausal, 9 T2D, BMI 31.5 kg/m2) underwent euglycemic-hyperinsulinemic-hypoglycemic and hyperglycemic clamps with assessments of counter-regulatory hormones and heart rate variability (HRV). Sex hormones (eg, testosterone, estradiol) were analyzed from fasting plasma samples. Results: Men vs women had higher responses of glucagon, ACTH, cortisol and GH but attenuated HRV responses during hypoglycemia and higher ACTH, more sympathetic dominance and lower GH levels during normo- and hyperglycemia. Post- vs premenopausal women had lower GH levels and less favorable HRV profiles but did not otherwise differ. Within-sex correlations between neurohormonal responses and sex hormones were generally weak. In multilinear regressions, M-value and waist-to-hip ratio were the strongest predictors of cortisol, ACTH and GH responses, whereas sex hormones did not explain within- or between-sex variations in neurohormonal responses. Conclusion: In healthy individuals as well as those with obesity or T2D, glucose-dependent counter-regulatory hormonal responses are elevated in men vs both pre- and postmenopausal women. This may contribute to insulin resistance and hence an increased risk of T2D development in men. Central adiposity, but not sex hormone profiles, may partly explain the observed sex differences.

Background: Alterations in kidney-associated adipose tissue depots, specifically renal sinus (RSAT) and perirenal adipose tissue (PRAT), may contribute to metabolic, cardiovascular, and chronic kidney diseases. We compared transcriptomic profiles and phenotypes, including adipocyte size, glucose uptake, and insulin action in RSAT and PRAT from healthy individuals. Methods: Subcutaneous (SAT), omental (OAT) and renal adipose tissue biopsies were collected from healthy kidney donors (20 women, 20 men; BMI 20 to 36 kg/m²). Adipocyte size and basal and insulin-stimulated glucose uptake rate were measured in isolated adipocytes. Transcriptomic profiling and immune cell composition estimates (RNA seq, n = 30), were performed to evaluate differences between PRAT and RSAT, with OAT as a benchmark. Results: PRAT exhibited significantly larger adipocytes and higher insulin-stimulated glucose uptake than RSAT. Of 1113 significantly differentially expressed genes (DEGs) (PRAT: 571 down- and 542 upregulated), thermogenic and metabolic genes (UCP1, CIDEA, and CKMT1B) were enriched in PRAT, while inflammation-related genes (NFKBIA, BIRC3, and IRF1) in RSAT. Pathway analysis indicated activation of metabolic pathways (TCA cycle and oxidative phosphorylation), in PRAT, which contrasts with the immune and inflammatory pathways in RSAT and OAT. Immune cell gene signatures revealed an anti-inflammatory environment in PRAT (eosinophils and activated NK cells), and a pro-inflammatory profile in RSAT (M0 macrophages). Immunohistochemistry confirmed higher CD68- and IL1B-positive cells in RSAT than in PRAT. When overweight individuals were compared to lean, genes related to the VEGF signaling were upregulated in PRAT and Ras signaling in RSAT. Additionally, metabolic pathways linked to the TCA cycle as well as carbon and fatty acid metabolism were downregulated. Conclusions: The different kidney-associated adipose tissue depots exhibit distinct gene expression and functional profiles. PRAT displays higher expression of thermogenic markers and less inflammatory profile compared to RSAT and also OAT. In contrast, RSAT exhibits an inflammatory and macrophage-enriched profile, more closely resembling OAT. This study highlights the heterogeneity of the kidney-associated adipose tissue depots and could suggest that an excessive amount of RSAT may impact development of metabolic, cardiovascular, and chronic kidney diseases.

Context: Obesity and insulin resistance in men are linked to decreased testosterone and increased estradiol (E2) levels. Aromatase (ARO) converts testosterone into E2, and this occurs mainly in adipose tissue in men. E2 acts through estrogen receptors ESR1 and ESR2, and they potentially affect development of type 2 diabetes (T2D). Objective: This study explored alterations in ARO, ESR1, and ESR2 in men with obesity or T2D. Methods: Subcutaneous adipose tissue (SAT) from men with or without obesity or T2D was analyzed for ARO, ESR1, and ESR2 gene and protein expression. Data were compared across groups and correlated with markers of obesity, glycemia, insulin resistance, and sex hormones. Moreover, SAT was incubated with E2 or testosterone for ex vivo glucose uptake measurements. Results: ARO levels were higher in SAT from men with obesity compared to nonobese men, and gene expression correlated positively with adiposity, hyperglycemia, and insulin resistance. No association was found between ARO and circulating E2. Men with obesity had lower levels of ESR1 and ESR1:ESR2 ratio, but not ESR2. ESR1 gene expression in SAT correlated negatively with adiposity and insulin resistance markers as well as with ARO expression, and tended to be lower in men with T2D. E2 reduced insulin-stimulated glucose uptake, while testosterone increased basal glucose uptake in adipocytes. Conclusion: Elevated ARO in SAT was found in obese men, and this was linked to insulin resistance and glycemia, supporting the idea that local estrogen production contributes to metabolic dysregulation. ESR1 was reduced in men with T2D and was linked to adiposity and insulin resistance. Taken together, high ARO and altered ESR1:ESR2 balance in SAT in obese men may contribute to insulin resistance and T2D development.

Objective: The objective was to study metabolic characteristics and transcriptome of renal sinus adipose tissue (RSAT) located around renal arteries and veins.Methods: Adipose tissue biopsies from RSAT, omental (OAT), and subcutaneous (SAT) depots were obtained from healthy kidney donors (20 female, 20 male). Adipocyte glucose uptake rate and cell size were measured, and gene expression analyses using transcriptomics were performed.Results: RSAT adipocytes were significantly smaller, with a higher basal glucose uptake rate, than adipocytes from SAT and OAT. Transcriptomic analyses revealed 29 differentially expressed genes between RSAT and OAT (RSAT: 23 lower, 6 higher) and 1214 differentially expressed genes between RSAT and SAT (RSAT: 859 lower, 355 higher). RSAT demonstrated molecular resemblance to OAT, both exhibiting lower metabolic gene expression and higher expression of immune‐related pathways, including IL‐17, TNFα, and NF‐κB signaling than SAT. Weighted gene coexpression network analysis associated RSAT with immune response and nucleic acid transport processes. Despite its location near the renal hilum, RSAT closely resembled OAT and there was a lack of expression in the classical brown adipose tissue genes. Gene enrichment analyses suggest an inflammatory environment in RSAT compared with SAT and, to some extent, OAT.Conclusions: The findings suggest specific RSAT functions that could impact renal function and, possibly, the development of renal and cardiometabolic disorders.

The global prevalence of Type 2 Diabetes (T2D) poses significant public health challenges due to its associated severe complications. Insulin resistance is central to T2D pathophysiology, particularly affecting adipose tissue function. This cross-sectional observational study investigates metabolic alterations in subcutaneous adipose tissue (SAT) associated with T2D to identify potential therapeutic targets. We conducted a comprehensive metabolomic analysis of SAT from 40 participants (20 T2D, 20 ND-T2D), matched for sex, age, and BMI (Body Mass Index). Metabolite quantification was performed using GC/MS and LC/MS/MS platforms. Correlation analyses were conducted to explore associations between metabolites and clinical parameters. We identified 378 metabolites, including significant elevations in TCA cycle (tricarboxylic acid cycle) intermediates, branched-chain amino acids (BCAAs), and carbohydrates, and a significant reduction in the nucleotide-related metabolites in T2D subjects compared to those without T2D. Obesity exacerbated these alterations, particularly in amino acid metabolism. Adipocyte size negatively correlated with BCAAs, while adipocyte glucose uptake positively correlated with unsaturated fatty acids and glycerophospholipids. Our findings reveal distinct metabolic dysregulation in adipose tissue in T2D, particularly in energy metabolism, suggesting potential therapeutic targets for improving insulin sensitivity and metabolic health. Future studies should validate these findings in larger cohorts and explore underlying mechanisms to develop targeted interventions.