Expression profiling by high throughput sequencing
Summary
Mechanistic insights into the molecular events by which exercise enhances the skeletal muscle phenotype are lacking, particularly in the context of type 2 diabetes. Here we unravel a fundamental role for exercise-responsive cytokines (exerkines) on skeletal muscle development and growth in individuals with normal glucose tolerance or type 2 diabetes. Acute exercise triggered an inflammatory response in skeletal muscle, concomitant with an infiltration of immune cells. These exercise effects were potentiated in type 2 diabetes. In response to contraction or hypoxia, cytokines were mainly produced by endothelial cells and macrophages. The chemokine CXCL12 was induced by hypoxia in endothelial cells, as well as by conditioned medium from contracted myotubes in macrophages. We found that CXCL12 was associated with skeletal muscle remodeling after exercise and differentiation of cultured muscle. Collectively, acute aerobic exercise mounts a non-canonical inflammatory response, with an atypical production of exerkines, which is potentiated in type 2 diabetes.
Overall design
Skeletal muscle biopsies were collected from normal glucose tolerant (NGT) and type 2 diabetic (T2D) middle age men, before (rest), just after (post) and 3-hours after (recovery) a 30-minute bout of cycling, at an intensity of 85% of measured maximal heart rate.
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