Obesity and exercise training alter inflammatory pathway skeletal muscle small extracellular vesicle microRNAs

Abstract

Obesity is associated with chronic inflammation characterized by increased levels of inflammatory cytokines, whereas exercise training reduces inflammation. Small extracellular vesicles (EVs; 30–150 nm) participate in cell‐to‐cell communication in part through microRNA (miRNA) post‐transcriptional regulation of mRNA. We examined whether obesity and concurrent aerobic and resistance exercise training alter skeletal muscle EV miRNA content and inflammatory signalling. Vastus lateralis biopsies were obtained from sedentary individuals with (OB) and without obesity (LN). Before and after 7 days of concurrent aerobic and resistance training, muscle‐derived small EV miRNAs and whole‐muscle mRNAs were measured. Pathway analysis revealed that obesity alters small EV miRNAs that target inflammatory (SERPINF1, death receptor and Gαi) and growth pathways (Wnt/β‐catenin, PTEN, PI3K/AKT and IGF‐1). In addition, exercise training alters small EV miRNAs in an anti‐inflammatory manner, targeting the IL‐10, IL‐8, Toll‐like receptor and nuclear factor‐κB signalling pathways. In whole muscle, IL‐8 mRNA was reduced by 50% and Jun mRNA by 25% after exercise training, consistent with the anti‐inflammatory effects of exercise on skeletal muscle. Obesity and 7 days of concurrent exercise training differentially alter skeletal muscle‐derived small EV miRNA contents targeting inflammatory and anabolic pathways.