s MicroRNAs Associated with Overweight and Obesity in Childhood: A Systematic Review

Background: Overweight and obesity prevalence has risen substantially in the last years. MicroRNAs (miRNAs) are factors that regulate gene expression through binding to a complementary sequence of mRNA. Objective: The objective of this review is to determine the association between the expression of miRNAs with overweight and obesity in children. Methods: A systematic search was carried out in Medline (Ovid), EMBASE, LILACS, and CENTRAL. Clinical trials, cohort studies, cases and controls, and cross-section studies were included. Quasi-experimental, prognostic studies, animal experiments, in silico studies, and studies on the adult population were excluded. Results: Seven studies (684 children) were included in this review. Three hundred and sixty-one children had obesity/overweight and 323 had normal weight. 40.64% (278) of the children were boys. The classification of obesity was inconsistent between the studies with several classifications used. A total of 65 miRNAs were reported to be associated with obesity and overweight; at least two studies reported miR-122, miR-122-5p, miR-15b, miR15b-5p, miR191-5p, miR-222, miR-222-3p, miR 486, miR-486-3p and miR-486-5p. Blood samples were the most common samples used to measure miRNAs, and the approaches to select miRNAs were diverse, with four articles performing high-throughput techniques (sequencing and microarrays) before the validation of the miRNAs associated with obesity. Pathway analysis of the repeated miRNAs showed that they were involved in the regulation of metabolic and signaling pathways, including fatty acid metabolism. Conclusion: miRNAs are potential biomarkers of the development of pathologies, such as obesity. It was found a heterogeneous group of these molecules was associated with obesity in children. miR- 15b-5p, miR-486-5p, and hsa-miR-122-5p were considered as good candidates for obesity biomarkers.