Elevated circulating microRNA-122 is associated with obesity and insulin resistance in young adults

Objective: MicroRNAs (miRNAs) are involved in the regulation of adiposity, but functional studies have yielded inconclusive results. Examining the associations of circulating miRNAs levels with obesity and insulin sensitivity in humans may lead to improved insights. Design and methods: Serum samples collected from 112 obese and control subjects (50.0% men) were randomly divided and combined into four pools (28 samples in each obese or control pool). The genome-wide circulating miRNA profiles were detected via microarray. Elevated miR-122 was selected and validated in individual serum samples from 123 obese (46.7% men) and 107 control (50.0% men) young adults. Associations between circulating miR-122 levels and parameters related to adiposity, insulin resistance, lipid profiles and hepatic enzymes were further assessed. Results: Thirty-four miRNAs were found to be expressed differently in the sera of obese patients compared with control subjects (P<0.001). Further analyses confirmed that obese patients had 3.07-fold higher circulating miR-122 levels than controls (P<0.001). Serum miR-122 levels were correlated with BMI (r=0.469), alanine aminotransferase (r=0.634), triglycerides (r=0.448), HDL-cholesterol (r=-0.351) and homeostasis model assessment of insulin resistance (r=0.401, all P<0.01). After controlling for confounding factors, miR-122 remained as an independent risk factor for insulin resistance (OR=3.379, 95% CI=1.141-10.007, P=0.028). Conclusions: Elevated circulating miR-122 is positively associated with obesity and insulin resistance in young adults. These findings provide a better understanding regarding the role of miRNAs in adiposity and insulin sensitivity.