The biological roles of exercise-induced cytokines: IL-6, IL-8, and IL-15

Anders Rinnov Nielsen, Bente Klarlund Pedersen


Skeletal muscle fibers express several cytokines, including interleukin (IL)-6, IL-8, and IL-15. Solid evidence exists that muscular IL-6 and IL-8 are regulated by muscle contractions, at both the mRNA and the protein levels. IL-6 increases insulin-stimulated glucose disposal and fatty acid oxidation in humans in vivo. Both IL-6 and IL-8 are released from working skeletal muscle, but because IL-6 contributes to the systemic circulation only a small transient net release of IL-8 is found from working muscle, suggesting that IL-8 may exert its effects locally in the muscle. IL-15 is a recently discovered growth factor, which is highly expressed in skeletal muscle. Interestingly, although IL-15 has been demonstrated as having anabolic effects on skeletal muscle in vitro and in vivo, it seems to play a role in reducing adipose tissue mass, and a role for IL-15 in muscle-fat cross-talk has been hypothesized. In conclusion, muscle-derived cytokines appear to have important roles in metabolism, and exercise plays a role in orchestrating the interplay between cytokines and metabolism.

Original languageEnglish
JournalApplied Physiology, Nutrition and Metabolism
Issue number5
Pages (from-to)833-9
Number of pages7
Publication statusPublished - Oct 2007
Externally publishedYes


  • Exercise/physiology
  • Humans
  • Interleukin-1/biosynthesis
  • Interleukin-15/biosynthesis
  • Interleukin-8/biosynthesis
  • Muscle Fibers, Skeletal/metabolism


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