The biological roles of exercise-induced cytokines: IL-6, IL-8, and IL-15.
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.
The Centre of Inflammation and Metabolism, Department of Infectious Diseases and CMRC Copenhagen University Hospital, Rigshospitalet, University of Copenhagen, Faculty of Health Sciences, DK-2100 Copenhagen, Denmark.
Anders Rinnov
AR
Nielsen
Bente Klarlund
BK
Pedersen
D015444:Exercise / Q000502:physiology*; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D019409:Interleukin-15 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*
D007375:Interleukin-1; D019409:Interleukin-15; D016209:Interleukin-8