Circulating miRNAs detect high versus low visceral adipose tissue inflammation in patients living with obesity
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ABSTRACT: Abstract: Background: The severity of visceral adipose tissue (VAT) inflammation in individuals with obesity is thought to signify obesity sub-phenotype(s) associated with higher cardiometabolic risk. Yet, this tissue is not accessible for direct sampling in the non-surgical patient. We hypothesized that circulating miRNAs (circ-miRs) could serve as biomarkers to distinguish human obesity subgroups with high or low extent of VAT-inflammation. Methods: Discovery and validation cohorts of patients living with obesity undergoing bariatric surgery (n=35 and 51, respectively) were included. VAT inflammation was classified into low/high based on an expression score derived from the mRNA levels of TNFA, IL6 and CCL2 (determined by rtPCR). Differentially-expressed circ-miRs were identified, and their discriminative power to detect low/high VAT inflammation was assessed by ROC-AUC analysis. Results: Fifty three out of 263 circ-miRs (20%) were associated with high VAT inflammation according to Mann-Whitney analysis in the discovery cohort. Of those, 12 (12/53=23%) were differentially expressed according to Deseq2, and 6 significantly discriminated between high and low VAT inflammation with ROC-AUC>0.8. Of the resulting 5 circ-miRs that were differentially abundant in all three statistical approaches, 3 were unaffected by hemolysis and validated in an independent cohort. Circ-miRs 181b-5p, 1306-3p, and 3138 combined with HOMA-IR exhibited ROC-AUC of 0.951 (95%CI:0.865-1) and 0.808 (95%CI:0.654-0.963) in the discovery and validation cohorts, respectively, providing strong discriminative power between participants with low versus high VAT inflammation. Predicted target genes of these miRNAs are enriched in pathways of insulin and inflammatory signaling, circadian entrainment, and cellular senescence. Conclusions: Circ-miRs that identify patients with low versus high VAT inflammation constitute a putative tool to improve personalized care of patients with obesity.
Project description:Visceral white adipose tissue (VAT) is susceptible to inflammation as a result of obesity, and this inflammation contributes to the development of obesity-related diseases. During the development of obesity, inflammatory immunocytes, including CD8+ T cells, Th1 cells, M1-like macrophages, neutrophils, and mast cells, accumulate in VAT. While these profound changes in the immunocyte composition of VAT lead to local inflammation, the triggers of VAT inflammation remain poorly understood. Therefore, a better understanding of the mechanisms underlying an early event of obesity-associated VAT inflammation will contribute to the development of novel therapies for obesity-related diseases. We utilized CellChat, which employs the expression of ligand-receptor pairs as indicators of intercellular communications, to examine the potential impact of these identified cell types within SVF on T cells. Our analysis revealed that ASCs exert the greatest influence on T cells in both lean and obese conditions. Finally, we demonstrated that ASCs promote Tcell infiltration into WAT during the early stages of obesity.
Project description:Obesity is associated with insulin resistance, an important risk factor of type 2 diabetes, atherogenic dyslipidemia, nonalcoholic fatty liver disease (NAFLD), and cardiovascular disease. It has been postulated that accumulation of visceral adipose tissue (VAT) causes obesity-induced insulin resistance. The major purpose of this study was to test hypothesis that prophylactic VAT removal prevents the development of obesity-induced multi-organ (liver, skeletal muscle, adipose tissue) insulin resistance, dyslipidemia, and NAFLD. Accordingly, we surgically removed epididymal VAT from adult C57BL/6J mice and then evaluated in vivo and cellular metabolic pathways involved in glucose and lipid metabolism following feeding of chronic high-fat diet (HFD). We found that VAT removal prevented HFD-induced insulin resistance and markedly increased AKT-mediated insulin signaling in subcutaneous adipose tissue (SAT), liver, and skeletal muscle. VAT removal improved plasma lipid profiling and prevented obesity-induced NAFLD. In addition, VAT removal significantly increased circulating level of adiponectin, a key insulin-sensitizing adipokine, whereas it decreased interleukin-6, a pro-inflammatory adipokine. Data obtained from RNA-sequencing suggest that VAT removal prevents obesity-induced oxidative stress and inflammation in liver and SAT respectively. These findings demonstrate the causative role of VAT in the development of obesity and related systemic metabolic complications, such as insulin resistance, dyslipidemia, and NAFLD.
Project description:Obesity can lead to type 2 diabetes and is an epidemic. A major contributor to its adverse effects is inflammation of the visceral adipose tisse (VAT). Life-long caloric restriction (CR), in contrast, results in extended lifespan, enhanced glucose tolerance/ insulin sensitivity, and other favorable phenotypes. The effects of CR following obesity are incompletely established, but studies show multiple benefits. Many leukocyte types, macrophages predominantly, reside in VAT in homeostatic and pathological states. CR following obesity transiently increases VAT macrophage content prior to resolution of inflammation and obesity, suggesting that macrophage content and phenotype play critical roles. Here, we examined the heterogeneity of VAT leukocytes and the effects of obesity and CR. In general, our single-cell RNA-sequencing data demonstrate that macrophages are the most abundant and diverse subpopulation of leukocytes in VAT. Obesity induced significant transcriptional changes in all 15 leukocyte subpopulations, with many genes showing coordinated changes in expression across leukocyte subpopulations. Additionally, obese VAT displayed expansion of one major macrophage subpopulation, which, in silico was enriched in lipid binding and metabolic processes. This subpopulation returned from dominance in obesity to lean proportions after only 2 weeks of CR, although the pattern of gene expression overall remained similar. Surprisingly, CR VAT is dominated by a different macrophage subpopulation, which is absent in lean conditions. This subpopulation is enriched in genes related to phagocytosis and we postulate that its function includes clearance of dead cells as well as excess lipids, contributing to limiting VAT inflammation and restoration of the homeostatic state.
Project description:Visceral adipose tissue (VAT) regulatory T cells (Tregs) control inflammation and metabolism. Diet-induced obesity causes hyperinsulinemia and diminishes VAT Treg number and function, but whether these two phenomena were mechanistically linked was unknown. We hypothesized that excessive insulin signaling in obesity negatively impact VAT Tregs. Using Treg-specific insulin receptor deletion (Foxp3-cre;Insr-fl/fl) mice, we compared the gene expression of VAT Tregs from control and knockout mice in obesity and aging, two models of hyperinsulinemia. We found that genes associated with Treg functions were altered in Tregs lacking insulin receptor.
Project description:Regulatory T (Treg) cells are highly enriched in the visceral adipose tissue (VAT) to maintain metabolic homeostasis, but they are lost during obesity. Currently, how VAT Treg cells rewire cellular metabolism to support their homeostatic clonal expansion, and whether this process is disrupted in obesity, is unclear. Here, we found that cholesterol metabolism was uniquely upregulated in VAT-, but not other non-lymphoid-tissue Treg cells. Disrupting cholesterol homeostasis (CH) by Treg-specific deletion of Srebf2 led to a specific loss of VAT Treg cells and enhanced obesity-induced systemic metabolic dysfunction. Mechanistically, Srebf2-mediated CH potentiated strong TCR signaling, which specifically promoted the clonal expansion of ST2hi, but not other, VAT Treg subsets. However, long-term high-fat-diet feeding disrupted VAT Treg CH and impaired ST2hi VAT Treg clonal expansion. Restoring Treg CH rescued VAT Treg accumulation in obese mice, suggesting CH modulation could be a potential option for Treg-targeted therapies in obesity-associated metabolic diseases.
Project description:The accumulation of visceral adipose tissue (VAT) is strongly associated with cardiovascular disease and diabetes. In contrast, individuals with increased subcutaneous adipose tissue (SAT) without corresponding increases in VAT are associated with a metabolic healthy obese phenotype. These observations implicate dysfunctional VAT as a driver of disease processes, warranting investigation into obesity-induced alterations of distinct adipose depots. To determine the effects of obesity on adipose gene expression, mice were fed either a high fat or normal laboratory diet for 12-14 months. Mesenteric VAT and hindlimb SAT were isolated from four lean controls and four obese mice for bulk RNA- sequencing. AT from lean controls served as a reference to obesity-induced changes. The long-term high fat diet induced the expression of 169 and 814 unique genes in SAT and VAT, respectively. SAT from obese mice exhibited a total of 308 differentially expressed genes (164 upregulated, 144 downregulated). VAT from obese mice exhibited 690 differentially expressed genes (262 genes upregulated, 428 downregulated). KEGG pathway and GO analyses revealed that metabolic pathways were upregulated in SAT vs. downregulated in VAT while inflammatory signaling was upregulated in VAT. We next determined common genes that were differentially regulated between SAT and VAT in response to obesity and identified four genes that exhibited this profile: elovl6 and kcnj15 were upregulated in SAT/downregulated in VAT while trdn and hspb7 were downregulated in SAT/ upregulated in VAT. We propose that these genes in particular should be further pursued to determine their roles in SAT vs. VAT with obesity.
Project description:We reported transcriptional characterization of vTreg53 TCR transgenic Treg cells from splenic and visceral adipose tissue (VAT) in mice fed with normal chow diet (NCD) or high fat diet (HFD) for different durations. We also reported transcriptional profile of VAT Treg cells stimulated by IFNa in vitro. Through this analysis, we found that the reduction of VAT Treg cells during obesity is driven by increased production of IFNa in VAT.
Project description:Regulatory T cells (Tregs) are key brakes on the VAT inflammation that regulates local and systemic metabolic tenor. The cytokine, IL-33, expands and sustains the unique Treg population residing within VAT. Making use of single-cell RNA sequencing, we identified the major IL-33 producers in VAT to be particular mSC subtypes, related to but distinct from adipocyte progenitor cells. We further characterize these subsets by individually isolating them and performing bulk-RNA sequencing. We explored modulation of the VAT-mSC (VmSC) landscape with physiologic variables such as age and sex, as well as pathogenic states like obesity. We uncovered a VAT Treg:stromal-cell negative regulatory loop that keeps the potent effect of IL-33 under rein.
Project description:Regulatory T cells (Tregs) are key brakes on the VAT inflammation that regulates local and systemic metabolic tenor. The cytokine, IL-33, expands and sustains the unique Treg population residing within VAT. Making use of single-cell RNA sequencing, we identified the major IL-33 producers in VAT to be particular mSC subtypes, related to but distinct from adipocyte progenitor cells. We further characterize these subsets by individually isolating them and performing bulk-RNA sequencing. We explored modulation of the VAT-mSC (VmSC) landscape with physiologic variables such as age and sex, as well as pathogenic states like obesity. We uncovered a VAT Treg:stromal-cell negative regulatory loop that keeps the potent effect of IL-33 under rein.
Project description:Adenomatous polyps adjacent to colorectal cancer (CRC) were found to exhibit two distinct microRNAs (miRs) patterns from normal mucosa to low- and separately, to high-grade dysplasia; presence in screen-detected adenoma of non-cancer patients is unknown. Global miR expression was performed on biopsies obtained from 109 healthy patients undergoing screening/surveillance colonoscopy. Included were normal mucosa (NM); hyperplastic polyp (HP); tubular adenoma (TA), tubulovillous adenoma, with or without, high-grade dysplasia (TVHG) and serrated-polyps; sessile serrated adenoma (SSA) and traditional serrated adenoma (TSA). Logistic regression was used to model miRs predictive of histology and CRC risk. We identified 99 miRs that differed across five histologic groups (FDR=0.05) and that accurately separated on histology (Concordance Index (CI)=0.96). In HPNM, miRs-145, -143, -107a, -23b, and -24 were upregulated whereas miRs-663, -1268, -320b, -1275, and -671 where overexpressed in TVHGs (FDR P<0 .05). The expression of miR-145 and -30a showed high accuracy to separate low from high-risk polyps independent of serrated status (CI= 97.1%; AUC 93.4%). For TSAs, miR-125b and -199a were uniquely downregulated relative to HPNMs and miR-335 discriminated between non-serrated and serrated histology. Histologically advanced polyps from non-cancer patients share miR alterations with those reported for CRC and high-grade adenoma adjacent to tumor including downregulation of immune regulatory miRs-125 and -199a in TSAs; polyp that frequently present with in situ carcinoma. These data extend evidence that miR patterns of high-risk adenoma are detectable in subset of screen-detected adenoma for which measurement may be useful in in adenoma risk stratification.