Diagnostic challenges in patients with reninomas and extrarenal renin-producing tumours.

Renin-secreting tumours are rare causes of secondary hypertension and hypokalaemia. They are usually surgically curable, hence proper diagnostic work-up and tumour localisation is essential. In this paper, we present three Swedish patients recently diagnosed with renin secreting tumours, two with reninomas and one with an extrarenal renin-producing tumour, to illustrate diagnostic challenges. We also discuss the biochemical work-up, the pros and cons of different imaging techniques (computer tomography [CT], magnetic resonance imaging and [18F]fluorodeoxyglucose-positron emission tomography-CT), as well as how renal vein sampling (RVC) may contribute to localisation of the tumour.

A spatiotemporal proteomic map of human adipogenesis.

White adipocytes function as major energy reservoirs in humans by storing substantial amounts of triglycerides, and their dysfunction is associated with metabolic disorders; however, the mechanisms underlying cellular specialization during adipogenesis remain unknown. Here, we generate a spatiotemporal proteomic atlas of human adipogenesis, which elucidates cellular remodelling as well as the spatial reorganization of metabolic pathways to optimize cells for lipid accumulation and highlights the coordinated regulation of protein localization and abundance during adipocyte formation. We identify compartment-specific regulation of protein levels and localization changes of metabolic enzymes to reprogramme branched-chain amino acids and one-carbon metabolism to provide building blocks and reduction equivalents. Additionally, we identify C19orf12 as a differentiation-induced adipocyte lipid droplet protein that interacts with the translocase of the outer membrane complex of lipid droplet-associated mitochondria and regulates adipocyte lipid storage by determining the capacity of mitochondria to metabolize fatty acids. Overall, our study provides a comprehensive resource for understanding human adipogenesis and for future discoveries in the field.

IMPROVE 2022 International Meeting on Pathway-Related Obesity: Vision of Excellence.

Nearly 90 clinicians and researchers from around the world attended the first IMPROVE 2022 International Meeting on Pathway-Related Obesity. Delegates attended in person or online from across Europe, Argentina and Israel to hear the latest scientific and clinical developments in hyperphagia and severe, early-onset obesity, and set out a vision of excellence for the future for improving the diagnosis, treatment, and care of patients with melanocortin-4 receptor (MC4R) pathway-related obesity. The meeting co-chair Peter Kühnen, Charité Universitätsmedizin Berlin, Germany, indicated that change was needed with the rapidly increasing prevalence of obesity and the associated complications to improve the understanding of the underlying mechanisms and acknowledge that monogenic forms of obesity can play an important role, providing insights that can be applied to a wider group of patients with obesity. World-leading experts presented the latest research and led discussions on the underlying science of obesity, diagnosis (including clinical and genetic approaches such as the role of defective MC4R signalling), and emerging clinical data and research with targeted pharmacological approaches. The aim of the meeting was to agree on the questions that needed to be addressed in future research and to ensure that optimised diagnostic work-up was used with new genetic testing tools becoming available. This should aid the planning of new evidence-based treatment strategies for the future, as explained by co-chair Martin Wabitsch, Ulm University Medical Center, Germany.

P2Y13 receptor deficiency favors adipose tissue lipolysis and worsens insulin resistance and fatty liver disease.

Excessive lipolysis in white adipose tissue (WAT) leads to insulin resistance (IR) and ectopic fat accumulation in insulin-sensitive tissues. However, the impact of Gi-coupled receptors in restraining adipocyte lipolysis through inhibition of cAMP production remained poorly elucidated. Given that the Gi-coupled P2Y13 receptor (P2Y13-R) is a purinergic receptor expressed in WAT, we investigated its role in adipocyte lipolysis and its effect on IR and metabolic dysfunction-associated steatotic liver disease (MASLD). In humans, mRNA expression of P2Y13-R in WAT was negatively correlated to adipocyte lipolysis. In mice, adipocytes lacking P2Y13-R displayed higher intracellular cAMP levels, indicating impaired Gi signaling. Consistently, the absence of P2Y13-R was linked to increased lipolysis in adipocytes and WAT explants via hormone-sensitive lipase activation. Metabolic studies indicated that mice lacking P2Y13-R showed a greater susceptibility to diet-induced IR, systemic inflammation, and MASLD compared with their wild-type counterparts. Assays conducted on precision-cut liver slices exposed to WAT conditioned medium and on liver-specific P2Y13-R-knockdown mice suggested that P2Y13-R activity in WAT protects from hepatic steatosis, independently of liver P2Y13-R expression. In conclusion, our findings support the idea that targeting adipose P2Y13-R activity may represent a pharmacological strategy to prevent obesity-associated disorders, including type 2 diabetes and MASLD.

Sex differences in adipose insulin resistance are linked to obesity, lipolysis and insulin receptor substrate 1.

BACKGROUND/OBJECTIVE: Insulin resistance is more prominent in men than women. If this involves adipose tissue is unknown and was presently examined. SUBJECTS/METHODS: AdipoIR (in vivo adipose insulin resistance index) was measured in 2344 women and 787 men. In 259 of the women and 54 of the men, insulin induced inhibition of lipolysis (acylglycerol breakdown) and stimulation of lipogenesis (glucose conversion to acylglycerols) were determined in subcutaneous adipocytes; in addition, basal (spontaneous) lipolysis was also determined in the fat cells. In 234 women and 115 men, RNAseq expression of canonical insulin signal genes were measured in subcutaneous adipose tissue. Messenger RNA transcripts of the most discriminant genes were quantified in 175 women and 109 men. RESULTS: Men had higher AdipoIR values than women but only when obesity (body mass index 30 kg/m2 or more) was present (p < 0.0001). The latter sex dimorphism was found among physically active and sedentary people, in those with and without cardiometabolic disease and in people using nicotine or not (p = 0.0003 or less). In obesity, adipocyte insulin sensitivity (half maximum effective hormone concentration) and maximal antilipolytic effect were tenfold and 10% lower, respectively, in men than women (p = 0.005 or less). Basal rate of lipolysis was two times higher in men than women (p > 0.0001). Sensitivity and maximum effect of insulin on lipogenesis were similar in both sexes (p = 0.26 and p = 0.18, respectively). When corrected for multiple comparison only RNAseq expression of insulin receptor substrate 1 (IRS1) was lower in men than women (p < 0.0001). The mRNA transcript for IRS1 was 60% higher in women than men (p < 0.0001). CONCLUSIONS: In obesity, adipose tissue insulin resistance is more pronounced in men than in women. The mechanism involves less efficient insulin-mediated inhibition of adipocyte lipolysis, increased basal rate of lipolysis and decreased adipose expression of a key element of insulin signaling, IRS1.

Targeted Proteomics Reveals Functional Targets for Early Diabetes Susceptibility in Young Adults.

BACKGROUND: The circulating proteome may encode early pathways of diabetes susceptibility in young adults for surveillance and intervention. Here, we define proteomic correlates of tissue phenotypes and diabetes in young adults. METHODS: We used penalized models and principal components analysis to generate parsimonious proteomic signatures of diabetes susceptibility based on phenotypes and on diabetes diagnosis across 184 proteins in >2000 young adults in the CARDIA (Coronary Artery Risk Development in Young Adults study; mean age, 32 years; 44% women; 43% Black; mean body mass index, 25.6±4.9 kg/m2), with validation against diabetes in >1800 individuals in the FHS (Framingham Heart Study) and WHI (Women's Health Initiative). RESULTS: In 184 proteins in >2000 young adults in CARDIA, we identified 2 proteotypes of diabetes susceptibility-a proinflammatory fat proteotype (visceral fat, liver fat, inflammatory biomarkers) and a muscularity proteotype (muscle mass), linked to diabetes in CARDIA and WHI/FHS. These proteotypes specified broad mechanisms of early diabetes pathogenesis, including transorgan communication, hepatic and skeletal muscle stress responses, vascular inflammation and hemostasis, fibrosis, and renal injury. Using human adipose tissue single cell/nuclear RNA-seq, we demonstrate expression at transcriptional level for implicated proteins across adipocytes and nonadipocyte cell types (eg, fibroadipogenic precursors, immune and vascular cells). Using functional assays in human adipose tissue, we demonstrate the association of expression of genes encoding these implicated proteins with adipose tissue metabolism, inflammation, and insulin resistance. CONCLUSIONS: A multifaceted discovery effort uniting proteomics, underlying clinical susceptibility phenotypes, and tissue expression patterns may uncover potentially novel functional biomarkers of early diabetes susceptibility in young adults for future mechanistic evaluation.

Insulin resistance in adipocytes: Novel insights into the pathophysiology of metabolic syndrome.

BACKGROUND: Insulin resistance in all major target tissues is present in metabolic syndrome (MetS). The resistance in adipocytes is not well described and was presently examined. METHODS: In this observational study on isolated abdominal white subcutaneous adipocytes from 419 adults, concentration-response effects of insulin on lipolysis inhibition (glycerol release) and lipogenesis stimulation (glucose conversion to total lipids) were determined. Insights into early and late insulin signaling events were obtained through the determination of insulin sensitivity (half maximum effective concentration) and responsiveness (maximum effect), respectively. In a subgroup of 132 subjects, we analyzed the subcutaneous adipose mRNA expression of genes in the canonical insulin signaling pathway using microarray. These results were validated using quantitative real-time polymerase chain reaction in 74 individuals. RESULTS: While the insulin responsiveness was similar in subjects with or without Mets, the sensitivity to insulin-mediated inhibition of lipolysis and stimulation of lipogenesis was ∼tenfold lower in subjects with MetS (p < 0.0001). When age, sex, adipocyte volume, body mass index and body shape were considered, only the antilipolytic resistance was independently associated with MetS. The mRNA expression of several genes in the canonical insulin signaling pathway were altered in MetS (p < 0.0006 or better) where the mRNA levels of insulin receptor substrate 2 associated with the antilipolytic effect (Rho = 0.34; p = 0.0016). CONCLUSION: The sensitivities of the antilipolytic and lipogenic effects of insulin are decreased in the MetS but only antilipolysis remains significant after multiple regression analysis. This resistance is localized at initial and receptor-near events in hormone signaling involving insulin receptor substrate 2.

Obesity causes mitochondrial fragmentation and dysfunction in white adipocytes due to RalA activation.

Mitochondrial dysfunction is a characteristic trait of human and rodent obesity, insulin resistance and fatty liver disease. Here we show that high-fat diet (HFD) feeding causes mitochondrial fragmentation in inguinal white adipocytes from male mice, leading to reduced oxidative capacity by a process dependent on the small GTPase RalA. RalA expression and activity are increased in white adipocytes after HFD. Targeted deletion of RalA in white adipocytes prevents fragmentation of mitochondria and diminishes HFD-induced weight gain by increasing fatty acid oxidation. Mechanistically, RalA increases fission in adipocytes by reversing the inhibitory Ser637 phosphorylation of the fission protein Drp1, leading to more mitochondrial fragmentation. Adipose tissue expression of the human homolog of Drp1, DNM1L, is positively correlated with obesity and insulin resistance. Thus, chronic activation of RalA plays a key role in repressing energy expenditure in obese adipose tissue by shifting the balance of mitochondrial dynamics toward excessive fission, contributing to weight gain and metabolic dysfunction.

Transcriptional determinants of lipid mobilization in human adipocytes.

Defects in adipocyte lipolysis drive multiple aspects of cardiometabolic disease, but the transcriptional framework controlling this process has not been established. To address this, we performed a targeted perturbation screen in primary human adipocytes. Our analyses identified 37 transcriptional regulators of lipid mobilization, which we classified as (i) transcription factors, (ii) histone chaperones, and (iii) mRNA processing proteins. On the basis of its strong relationship with multiple readouts of lipolysis in patient samples, we performed mechanistic studies on one hit, ZNF189, which encodes the zinc finger protein 189. Using mass spectrometry and chromatin profiling techniques, we show that ZNF189 interacts with the tripartite motif family member TRIM28 and represses the transcription of an adipocyte-specific isoform of phosphodiesterase 1B (PDE1B2). The regulation of lipid mobilization by ZNF189 requires PDE1B2, and the overexpression of PDE1B2 is sufficient to attenuate hormone-stimulated lipolysis. Thus, our work identifies the ZNF189-PDE1B2 axis as a determinant of human adipocyte lipolysis and highlights a link between chromatin architecture and lipid mobilization.

Exercise-induced crosstalk between immune cells and adipocytes in humans: Role of oncostatin-M.

The discovery of exercise-regulated circulatory factors has fueled interest in organ crosstalk, especially between skeletal muscle and adipose tissue, and the role in mediating beneficial effects of exercise. We studied the adipose tissue transcriptome in men and women with normal glucose tolerance or type 2 diabetes following an acute exercise bout, revealing substantial exercise- and time-dependent changes, with sustained increase in inflammatory genes in type 2 diabetes. We identify oncostatin-M as one of the most upregulated adipose-tissue-secreted factors post-exercise. In cultured human adipocytes, oncostatin-M enhances MAPK signaling and regulates lipolysis. Oncostatin-M expression arises predominantly from adipose tissue immune cell fractions, while the corresponding receptors are expressed in adipocytes. Oncostatin-M expression increases in cultured human Thp1 macrophages following exercise-like stimuli. Our results suggest that immune cells, via secreted factors such as oncostatin-M, mediate a crosstalk between skeletal muscle and adipose tissue during exercise to regulate adipocyte metabolism and adaptation.

Adipogenic characterization of immortalized CD55+ progenitor cells from human white adipose tissue.

BACKGROUND: Mature adipocytes are notoriously difficult to study ex vivo and alternative cell culture systems have therefore been developed. One of the most common models are human adipose progenitor cells (hAPCs). Unfortunately, these display replicative senescence after prolonged culture conditions, which limits their use in mechanistic studies. METHODS: Herein, we knocked in human telomerase reverse transcriptase (TERT) into the AAVS1 locus of CD55+ hAPCs derived from abdominal subcutaneous adipose tissue and characterized the cells before and after differentiation into adipocytes. RESULTS: Immortalized TERT-hAPCs retained proliferative and adipogenic capacities comparable to those of early-passage wild type hAPCs for > 80 passages. In line with this, our integrative transcriptomic and proteomic analyses revealed that TERT-hAPCs displayed robust adipocyte expression profiles in comparison to wild type hAPCs. This was confirmed by functional analyses of lipid turnover where TERT-hAPCs exhibited pronounced responses to insulin and pro-lipolytic stimuli such as isoprenaline, dibutyrul cAMP and tumour necrosis factor alpha. In addition, TERT-hAPCs could be readily cultured in both standard 2D and 3D-cultures and proteomic analyses revealed that the spheroid culture conditions improved adipogenesis. CONCLUSION: Through descriptive and functional studies, we demonstrate that immortalization of human CD55+ hAPCs is feasible and results in cells with stable proliferative and adipogenic capacities over multiple passages. As these cells are cryopreservable, they provide the additional advantage over primary cells of allowing repeated studies in both 2D and 3D model systems with the same genetic background. (234/250).

CRISPR/Cas9-mediated deletion of adipocyte genes associated with NAFLD alters adipocyte lipid handling and reduces steatosis in hepatocytes in vitro.

Obesity is a major risk factor for the development of nonalcoholic fatty liver disease (NAFLD), and the subcutaneous white adipose tissue (scWAT) is the primary lipid storage depot and regulates lipid fluxes to other organs. Our previous work identified genes upregulated in scWAT of patients with NAFLD: SOCS3, DUSP1, and SIK1. Herein, we knocked down (KD) their expression in human adipose-derived mesenchymal stem cells (hADMSCs) using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology and characterized their phenotype. We found that SOCS3, DUSP1, and SIK1 expression in hADMSC-derived adipocytes was not critical for adipogenesis. However, the metabolic characterization of the cells suggested that the genes played important roles in lipid metabolism. Reduction of SIK1 expression significantly increased both de novo lipogenesis (DNL) and palmitate-induced lipogenesis (PIL). Editing out SOCS3 reduced DNL while increasing isoproterenol-induced lipolysis and insulin-induced palmitate accumulation. Conversely, DUSP1 reduced PIL and DNL. Moreover, RNA-sequencing analysis of edited cells showed that these genes not only altered lipid metabolism but also other biological pathways related to inflammatory processes, in the case of DUSP1, extracellular matrix remodeling for SOCS3, or cellular transport for SIK1. Finally, to evaluate a possible adipocyte-hepatocyte axis, human hepatoma HepG2 cells were cocultured with edited hADMSCs-derived adipocytes in the presence of [3H]-palmitate. All HepG2 cells cultured with DUSP1-, SIK1-, or SOCS3-KD adipocytes decreased [3H]-palmitate accumulation compared with control adipocytes. These results support our hypotheses that SOCS3, DUSP1, and SIK1 regulate multiple aspects of adipocyte function, which may play a role in the progression of obesity-associated comorbidities, such as NAFLD.NEW & NOTEWORTHY Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology successfully edited genomic DNA of human adipose-derived mesenchymal stem cells (hADMSC). SOCS3, SIK1, and DUSP1 regulate adipocyte lipid handling. Silencing SOCS3, SIK1, and DUSP1 expression in hADMSC-derived adipocytes reduces hepatocyte lipid storage in vitro.

Obesity-dependent increase in RalA activity disrupts mitochondrial dynamics in white adipocytes.

Mitochondrial dysfunction is a characteristic trait of human and rodent obesity, insulin resistance, and fatty liver disease. Here we report that mitochondria undergo fragmentation and reduced oxidative capacity specifically in inguinal white adipose tissue after feeding mice high fat diet (HFD) by a process dependent on the small GTPase RalA. RalA expression and activity are increased in white adipocytes from mice fed HFD. Targeted deletion of Rala in white adipocytes prevents the obesity-induced fragmentation of mitochondria and produces mice resistant to HFD-induced weight gain via increased fatty acid oxidation. As a result, these mice also exhibit improved glucose tolerance and liver function. In vitro mechanistic studies revealed that RalA suppresses mitochondrial oxidative function in adipocytes by increasing fission through reversing the protein kinase A-catalyzed inhibitory Ser637phosphorylation of the mitochondrial fission protein Drp1. Active RalA recruits protein phosphatase 2A (PP2Aa) to specifically dephosphorylate this inhibitory site on Drp1, activating the protein, thus increasing mitochondrial fission. Adipose tissue expression of the human homolog of Drp1, DNML1, is positively correlated with obesity and insulin resistance in patients. Thus, chronic activation of RalA plays a key role in repressing energy expenditure in obese adipose tissue by shifting the balance of mitochondrial dynamics towards excessive fission, contributing to weight gain and related metabolic dysfunction.

Habitual nappers and non-nappers differ in circadian rhythms of LIPE expression in abdominal adipose tissue explants.

Background and purpose: Napping is a widespread practice worldwide and has in recent years been linked to increased abdominal adiposity. Lipase E or LIPE encodes the protein hormone-sensitive lipase (HSL), an enzyme that plays an important role in lipid mobilization and exhibits a circadian expression rhythm in human adipose tissue. We hypothesized that habitual napping may impact the circadian expression pattern of LIPE, which in turn may attenuate lipid mobilization and induce abdominal fat accumulation. Methods: Abdominal adipose tissue explants from participants with obesity (n = 17) were cultured for a 24-h duration and analyzed every 4 h. Habitual nappers (n = 8) were selected to match non-nappers (n = 9) in age, sex, BMI, adiposity, and metabolic syndrome traits. Circadian LIPE expression rhythmicity was analyzed using the cosinor method. Results: Adipose tissue explants exhibited robust circadian rhythms in LIPE expression in non-nappers. In contrast, nappers had a flattened rhythm. LIPE amplitude was decreased in nappers as compared with non-nappers (71% lower). The decrease in amplitude among nappers was related to the frequency of napping (times per week) where a lower rhythm amplitude was associated with a higher napping frequency (r = -0.80; P = 0.018). Confirmatory analyses in the activity of LIPE's protein (i.e., HSL) also showed a significant rhythm in non-nappers, whereas significance in the activity of HSL was lost among nappers. Conclusion: Our results suggest that nappers display dysregulated circadian LIPE expression as well as dysregulated circadian HSL activity, which may alter lipid mobilization and contribute to increased abdominal obesity in habitual nappers.

Adipose Insulin Resistance Associates With Dyslipidemia Independent of Liver Resistance and Involves Early Hormone Signaling.

BACKGROUND: Adipose tissue insulin resistance is linked to altered plasma levels of triglycerides and HDL (high-density lipoprotein)-cholesterol. However, its degree of independence from liver resistance and different metabolic traits (lipolysis, lipogenesis) effected is not clear and was presently investigated. METHODS: In 3290 adult subjects, plasma levels of triglycerides and HDL-cholesterol were cross-sectionally measured and related to interindividual variations in measures of insulin resistance in the liver (homeostasis mode assessment of insulin resistance index) or adipose tissue (Adipo-IR index). In subgroups, insulin-induced antilipolysis and lipogenesis in isolated subcutaneous fat cells (n=578) were determined alongside global adipose tissue gene expression (n=132). RESULTS: Using linear regression, homeostasis mode assessment of insulin resistance and Adipo-IR strongly correlated with the plasma lipids explaining 33% of the variations in triglycerides. Together with other variables (age, sex, body mass index, cardiometabolic disorders, nicotine use, ethnicity, and physical activity) in multiple regression, homeostasis mode assessment of insulin resistance, and Adipo-IR each remained an important regressor for triglycerides and HDL-cholesterol (P<0.0001). In fat cells, half-maximum effective concentration but not maximum effect of insulin on antilipolysis and lipogenesis contributed independently to variations in triglycerides and HDL-cholesterol (P=0.001 or lower). This was linked to expression of the insulin receptor, insulin receptor substrate-1, and AKT serine/threonine kinase 2 in adipose tissue. CONCLUSIONS: Markers of insulin resistance in the liver and adipose tissue each associate strongly, and independently of each other, to elevated triglycerides and decreased HDL levels. At the fat cell, early insulin receptor signaling and sensitivity, but not maximum insulin action contributes to the variations in circulating triglycerides and HDL-cholesterol.

An integrated single cell and spatial transcriptomic map of human white adipose tissue.

To date, single-cell studies of human white adipose tissue (WAT) have been based on small cohort sizes and no cellular consensus nomenclature exists. Herein, we performed a comprehensive meta-analysis of publicly available and newly generated single-cell, single-nucleus, and spatial transcriptomic results from human subcutaneous, omental, and perivascular WAT. Our high-resolution map is built on data from ten studies and allowed us to robustly identify >60 subpopulations of adipocytes, fibroblast and adipogenic progenitors, vascular, and immune cells. Using these results, we deconvolved spatial and bulk transcriptomic data from nine additional cohorts to provide spatial and clinical dimensions to the map. This identified cell-cell interactions as well as relationships between specific cell subtypes and insulin resistance, dyslipidemia, adipocyte volume, and lipolysis upon long-term weight changes. Altogether, our meta-map provides a rich resource defining the cellular and microarchitectural landscape of human WAT and describes the associations between specific cell types and metabolic states.

Relationship Between a Sedentary Lifestyle and Adipose Insulin Resistance.

Sedentary people have insulin resistance in their skeletal muscle, but whether this also occurs in fat cells was unknown. Insulin inhibition of hydrolysis of triglycerides (antilipolysis) and stimulation of triglyceride formation (lipogenesis) were investigated in subcutaneous fat cells from 204 sedentary and 336 physically active subjects. Insulin responsiveness (maximum hormone effect) and sensitivity (half-maximal effective concentration) were determined. In 69 women, hyperinsulinemia-induced circulating fatty acid levels were measured. In 128 women, adipose gene expression was analyzed. Responsiveness of insulin for antilipolysis (60% inhibition) and lipogenesis (twofold stimulation) were similar between sedentary and active subjects. Sensitivity for both measures decreased ˜10-fold in sedentary subjects (P < 0.01). However, upon multiple regression analysis, only the association between antilipolysis sensitivity and physical activity remained significant when adjusting for BMI, age, sex, waist-to-hip ratio, fat-cell size, and cardiometabolic disorders. Fatty acid levels decreased following hyperinsulinemia but remained higher in sedentary compared with active women (P = 0.01). mRNA expression of insulin receptor and its substrates 1 and 2 was decreased in sedentary subjects. In conclusion, while the maximum effect is preserved, sensitivity to insulin's antilipolytic effect in subcutaneous fat cells is selectively lower in sedentary subjects.

Associations between subcutaneous adipocyte hypertrophy and nonalcoholic fatty liver disease.

Adipocyte hypertrophy and expression of adipokines in subcutaneous adipose tissue (SAT) have been linked to steatosis, nonalcoholic steatohepatitis (NASH) and fibrosis in morbidly obese (BMI ≥ 40 kg/m2) subjects. It is unknown if this is also true for subjects with NAFLD with lesser degrees of obesity (BMI < 35 kg/m2). Thirty-two subjects with biopsy-proven NAFLD and 15 non-diabetic controls matched for BMI underwent fine-needle biopsies of SAT. Adipocyte volume was calculated. RNA-sequencing of SAT was performed in a subset of 20 NAFLD patients. Adipocyte volume and gene expression levels were correlated to the presence of NASH or significant fibrosis. Subjects with NAFLD had larger adipocyte volume compared with controls, (1939 pL, 95% CI 1130-1662 vs. 854 pL, 95% CI 781-926, p < 0.001). There was no association between adipocyte volume and the presence of NASH. Gene expression of adipokines previously described to correlate with NASH in morbid obesity, was not associated with NASH or fibrosis. Our results suggest that persons with NAFLD have larger SAT adipocytes compared with controls and that adipocytes are involved in the pathophysiology of hepatic steatosis in NAFLD. However, adipocyte volume was not associated with NASH or fibrosis in NAFLD subjects with varying degrees of obesity.

Sex-specific regulation of IL-10 production in human adipose tissue in obesity.

Background: Obesity-associated metabolic complications display sexual dimorphism and can be impacted by cytokines. We previously showed that interleukin-10 (IL-10) was upregulated in white adipose tissue (WAT) of obese women with type 2 diabetes (T2D). Whether this pertains to men is unknown. The aim of this study was to compare the impact of obesity and T2D on WAT IL-10 levels in men versus women. Methods: Plasma and subcutaneous WAT biopsies were obtained from 108 metabolically well-characterized individuals. WAT IL10 expression/secretion and WAT-resident IL-10-secreting macrophage number were measured. Circulating sex hormone levels were correlated to WAT IL10 expression in 22 individuals and sex hormone effects on macrophage IL10 expression were investigated in vitro. Results: Obese women with T2D showed increased IL10 expression/secretion and IL-10-secreting WAT macrophage number compared to other female groups. This difference was absent in men. Non-obese women and men with T2D showed similar IL-10 levels compared to healthy controls, indicating that T2D alone does not regulate IL-10. Although WAT IL10 expression correlated with serum estrone (E1) concentrations, recombinant E1 did not affect macrophage IL10 expression in vitro. Conclusion: WAT IL-10 levels are higher in women with obesity and T2D, but not in men and this effect is primarily attributed to obesity per se. This is less likely to be driven by circulating sex hormones. We propose that the WAT IL-10 might exert protective effects in obesity-associated chronic inflammation in women which could be one of the contributing factors for the decreased morbidity observed in women during obesity than men.