miRNA Signatures of Insulin Resistance in Obesity

Objective: Extracellular microRNAs (miRNAs) represent functional biomarkers for obesity and related disorders; this study investigated plasma miRNAs in insulin resistance phenotypes in obesity. Methods: One hundred seventy-five miRNAs were analyzed in females with obesity (insulin sensitivity, n511; insulin resistance, n519; type 2 diabetes, n515) and without obesity (n512). Correlations between miRNA level and clinical parameters and levels of 15 miRNAs in a murine obesity model were investigated. Results: One hundred six miRNAs were significantly (adjusted P[1]0.05) different between controls and at least one obesity phenotype, including miRNAs with the following attributes: previously reported roles in obesity and altered circulating levels (e.g., miR-122, miR-192); known roles in obesity but no reported changes in circulating levels (e.g., miR-378a); and no current reported role in, or association with, obesity (e.g., miR-28-5p, miR-374b, miR-32). The miRNAs in the latter group were found to be associated with extracellular vesicles. Forty-eight miRNAs showed significant correlations with clinical parameters; stepwise regression retained let-7b, miR-144-5p, miR-34a, and miR-532-5p in a model predictive of insulin resistance (R250.57, P57.531028). Both miR-378a and miR-122 were perturbed in metabolically relevant tissues in a murine model of obesity. Conclusions: This study expands on the role of extracellular miRNAs in insulin-resistant phenotypes of obesity and identifies candidate miRNAs not previously associated with obesity.