Integratome analysis of adipose tissues reveals abnormal epigenetic regulation of adipogenesis, inflammation, and insulin signaling in obese individuals with type 2 diabetes

Type 2 diabetes (T2D) is associated with cardiovascular-renal complications and premature death. Although most patients with T2D are obese, not all obese individuals develop T2D. Thus, an understanding of the mechanistic relationships between obesity and T2D is crucial. In this study, using subcutaneous (SAT) and visceral adipose tissues (VAT) from obese individuals with or without T2D collected during metabolic surgery, integration of the transcriptomes and methylomes of VAT and SAT with publicly available tissue-specific regulatory networks, we discovered the close relation between T2D and inflammatory response in both SAT and VAT in obese individuals, although less differences were observed respectively in transcriptome or methylome. Specifically, a HOX gene family-enriched functional epigenetic sub-network in T2D-SAT, as well as a novel such sub-network was discovered, which involved multiple genes implicated in activation of obesity-induced inflammatory response. Our integrated approach of using biosamples, multi-omic data and public databases to understand complex diseases for discovery of novel biology, including biomarkers and drug targets, can be applied to diseases other than T2D and obesity. 40 methylation samples from 24 individuals were sequenced, including SAT from 10 T2D and 9 control individuals and VAT from 10 T2D and 11 control individuals.