Ageing influences the relationship of circulating miR-33a and miR-33b levels with insulin resistance and adiposity

Objective: The identification of circulating microRNAs related to abnormal metabolic function may be useful in the context of ageing, adiposity and insulin resistance. The miR-33a/b has been shown to control the expression of genes involved in fatty acid biosynthesis, impaired metabolism and insulin resistance. In this study, we aimed to identify differences in circulating miR-33a/b levels according to age-related metabolic impairment and increased adiposity. Methods: This study included 80 individuals (30.2% with obesity, 70% females) classified according to insulin resistance (Stern's criteria) and age [young (20-39 years) and senior (40-59 years)]. Body fat was evaluated using bioelectrical impedance, biochemical markers by colorimetric, enzymatic and immuno-turbidimetry methods. TaqMan measures of circulating miR-33a and miR-33b with quantitative reverse transcription polymerase chain reaction in serum were assessed in association with clinical outputs. Results: Circulating miR-33a and miR-33b levels showed significant association with fatness, the lipid profile and biomarkers of impaired glucose metabolism. Both miR-33a and miR-33b were associated with visceral adiposity index in non-insulin resistance and insulin resistance individuals. More important, for miR-33a circulating levels in senior group, receiver operating characteristic curve analyses showed area under the curve 0.804 (p = 0.010; 95% confidence interval = 0.655-0.952). Conclusion: Ageing influenced the relationship of circulating miR-33a and miR-33b with insulin resistance and increased adiposity.