Candidate Circulating microRNAs in Patients with Sarcopenic Obesity: Results of a Pilot Screening

Background/Objectives: Sarcopenic obesity (SO) represents a severe clinical phenotype characterized by the coexistence of reduced skeletal muscle mass and excess adiposity, and is associated with insulin resistance, dyslipidemia, and systemic inflammation. However, easily accessible biomarkers that capture early molecular changes underlying SO are lacking. The aim of this pilot study was to compare circulating microRNA (miRNA) profiles in patients with severe obesity and a sarcopenic obesity phenotype with those of healthy controls and to identify candidate miRNAs suitable for further validation. To the best of our knowledge, this represents one of the first broad screening studies of circulating miRNAs specifically conducted in patients with severe obesity and DXA-confirmed sarcopenic obesity. Methods: In this single-center pilot study conducted in the Czech Republic, fasting plasma samples from 12 adult participants (6 with severe obesity and sarcopenic obesity phenotype, body mass index > 45 kg/m²; 6 healthy controls; age 18-65 years) were analyzed using an RT-qPCR panel comprising 384 assays, including technical controls and 352 target circulating miRNAs. Following predefined quality control and filtering criteria, 224 miRNAs were retained for the final statistical analysis. Six patients with severe obesity were classified according to the ESPEN/EASO 2022 consensus criteria for sarcopenic obesity, while EWGSOP2-based assessment was used for functional evaluation of sarcopenia. Differential expression was evaluated using fold change and exploratory statistical testing. Results: We identified a set of miRNAs with significantly altered expression in SO, including increased muscle-enriched miR-486-5p and hepatocyte-enriched miR-122-5p, and decreased vascular miR-145-5p, as well as several additional miRNAs related to myogenesis, lipid metabolism and inflammatory signaling. miR-451a, a recognized marker of hemolysis, was also increased but was interpreted with caution. Conclusions: Despite the limited sample size, the results of this study suggest that specific circulating miRNAs may reflect key pathophysiological pathways in SO and could serve as promising biomarkers to support risk stratification and monitoring in larger, hypothesis-driven studies.