A dynamic subcutaneous adipose transcriptome of human insulin resistance identifies a molecular predisposition shared with visceral adipose tissue
Subcutaneous adipose tissue (SAT) is classically viewed as a metabolic buffer for lipid deposition during positive caloric balance, while visceral adipose tissue (VAT) is viewed as the dominant contributor and prime mediator of insulin resistance (IR) and cardiometabolic disease risk. Nevertheless, a growing body of data suggests that similar morphologic and molecular changes may occur in SAT as in VAT during obesity. In addition, while pro-inflammatory immune changes within adipose are thought to drive IR there is increasing data implicating a role for adipocytes and stromal populations especially in humans. Here, we identified a transcriptional landscape of IR in SAT of 220 humans across the spectrum of obesity and IR states, highlighting a broad range of metabolic pathways central to IR. Using single cell and nucleus deconvolution and statistical learning techniques, we identified a 35-gene signature that (1) achieved high predictive accuracy for homeostatic model of IR (HOMA-IR) across BMI; (2) was expressed across a variety of non-immune cell populations (most prominently adipocytes and adipocyte stem and precursor cells [ASPCs]), with primarily “protective” IR associations for adipocyte transcripts and “deleterious” associations for macrophage transcripts; (3) displayed a high concordance between SAT and VAT (greater than non-IR associated genes). Multiple SAT genes exhibited dynamic expression 5-years after weight loss surgery and with insulin stimulation. Finally, using available expression quantitative trait loci in SAT and/or VAT, we demonstrate similar genetic effect sizes of SAT and VAT on type 2 diabetes and BMI, suggesting underlying similarities in genetic determinants of IR between adipose depots. These results implicate a dynamic transcriptional architecture of IR that resides in both immune and non-immune populations in SAT and that is shared with VAT, nuancing the current VAT-centric concept of IR in humans. Overall design: The discovery cohort consisted of 76 samples collected from individuals with obesity and pre-diabetes by lipoaspiration from the subcutaneous adipose depot. These individuals had matching metadata including height, weight, and measures of insulin resistance.