MicroRNAs (miRNAs) regulate several metabolic pathways and are potential biomarkers for early risk prediction of metabolic syndrome (MetS). Our aim was to evaluate the levels of 21 miRNAs in plasma according to MetS components and sex in adults. We employed a cross-sectional study of 192 adults aged 20 to 59 years old from the 2015 Health Survey of São Paulo with Focus in Nutrition. Data showed reduced levels of miR-16 and miR-363 in women with MetS; however, men with one or more risk factors showed higher levels of miR-let-7c and miR-30a. Individuals with raised waist circumference showed higher levels of miR-let-7c, miR-122, miR-30a, miR-146a, miR-15a, miR-30d and miR-222. Individuals with raised blood pressure had higher miR-30a, miR-122 and miR-30a levels. Plasma levels of four miRNAs (miR-16, miR-363, miR-375 and miR-486) were lower in individuals with low HDL-cholesterol concentrations. In addition, plasma levels of five miRNAs (miR-122, miR-139, miR-let-7c, miR-126 and miR-30a) were increased in individuals with high fasting plasma glucose and/or insulin resistance. Our results suggest that the pattern of miRNA levels in plasma may be a useful early biomarker of cardiometabolic components of MetS and highlight the sex differences in the plasma levels of miRNAs in individuals with MetS.

MicroRNA regulates multiple pathways in inflammatory response, adipogenesis, and glucose and lipid metabolism, which are involved in metabolic syndrome (MetS). Thus, this systematic review aimed at synthesizing the evidence on the relationships between circulating microRNA and risk factors for MetS. The systematic review was registered in the PROSPERO database (CRD42020168100) and included 24 case-control studies evaluating microRNA expression in serum/plasma of individuals ≥5 years old. Most of the studies focused on 13 microRNAs with higher frequency and there were robust connections between miR-146a and miR-122 with risk factors for MetS, based on average weighted degree. In addition, there was an association of miR-222 with adiposity, lipid metabolism, glycemic metabolism, and chronic inflammation and an association of miR-126, miR-221, and miR-423 with adiposity, lipid, and glycemic metabolism. A major part of circulating microRNA was upregulated in individuals with risk factors for MetS, showing correlations with glycemic and lipid markers and body adiposity. Circulating microRNA showed distinct expression profiles according to the clinical condition of individuals, being particularly linked with increased body fat. However, the exploration of factors associated with variations in microRNA expression was limited by the variety of microRNAs investigated by risk factor in diverse studies identified in this systematic review.

Background/Objectives: Insulin resistance (IR) in adolescents contributes to the development of metabolic and immunological alterations. These alterations can lead to chronic, systemic, low-grade inflammation in adulthood. Evidence suggests that alterations in miRNA expression play a significant role in the onset of IR by influencing insulin signaling pathways. Therefore, identifying specific miRNAs may aid in the early diagnosis of cardiometabolic risk, particularly during the transition from adolescence to adulthood. Methods: This population-based study aimed to analyze the expression of 21 miRNAs in the plasma of adolescents. We considered IR status, overweight, sex, and age for the analyses. The study measured miRNA expression in plasma samples from 187 adolescents aged 12 to 19 years from the cross-sectional study of the 2015 São Paulo Health Survey (ISA-Nutrition). MiRNA expression was assessed using Exiqon^® assays on Fluidigm^® technology (Les Ulis, France). Statistical analyses were performed to identify differences in miRNA expression and correlations between variables, using a complex research design to ensure representativeness at the population level. Results: The incidence of IR and overweight was high in adolescents (44% and 33%, respectively). High-sensitivity C-reactive protein (hs-CRP) concentration was higher in overweight adolescents. IR was correlated with higher plasma expression of miR-122 and miR-139-3p. Furthermore, miR-486, miR-363, miR-30d, miR-28, miR-223, miR-21, miR-146, miR-130b, miR-126, miR-122, and miR-139-3p showed specific correlations with individual risk for IR, sex, and adolescent stage. Conclusions: The miRNAs showed differential expression according to sex and adolescent stage, and were correlated with cardiometabolic risk factors, suggesting their potential utility for early screening in adolescents. The study highlights age- and sex-related differences in miRNA levels between adolescents with IR and overweight. The cross-sectional design is a limitation of this study, as we cannot infer causality for the associations observed here.