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

Obesity is associated with chronic inflammation characterized by increased levels of inflammatory cytokines, while exercise training reduces inflammation. Small EVs (30-150 nm) participate in cell-to-cell communication in part through miRNA post-transcriptional regulation of mRNA. Purpose: The current study examined if obesity and concurrent exercise training alter skeletal muscle: (1) EV miRNA content and (2) inflammatory signaling. Methods: Vastus lateralis biopsies were obtained from sedentary individuals with (OB) and without obesity (LN). Before and after seven days of concurrent aerobic and resistance training, muscle-derived small EV miRNA and whole muscle mRNA were measured. Results: Pathway analysis revealed that obesity alters small EV miRNA that target inflammatory (PEDF, Death Receptor, and Gαi) and growth pathways (Wnt/β-catenin, PTEN, PI3K/AKT, IGF-1). In addition, exercise training alters small EV miRNA in an anti-inflammatory manner targeting the IL-10, IL-8, toll-like receptor (TLR), and NF-κB signaling pathways. In whole muscle, IL-8 mRNA was reduced 50% and Jun mRNA was reduced 25% after exercise training consistent with the anti-inflammatory effects of exercise on skeletal muscle. Conclusions: Obesity and seven days of concurrent exercise training differentially alter skeletal muscle-derived small EV miRNA contents targeting inflammatory and anabolic pathways.

https://doi.org/10.1113/EP090062