title: Interleukin-6 production by contracting human skeletal muscle: autocrine regulation by IL-6.
abstract: Interleukin-6 (IL-6) is a cytokine with immuno-regulatory functions. However, contracting skeletal muscle expresses and subsequently releases IL-6 in high amounts, and recent evidence in IL-6 deficient mice suggests a role of IL-6 in metabolism. Since IL-6 mRNA levels also increase in abdominal adipose tissue in response to exercise, we wanted to examine the possible existence of a positive feedback mechanism between muscle and adipose tissue. We obtained biopsies from human skeletal muscle and abdominal subcutaneous adipose tissue in relation to either 3h of bicycle exercise or recombinant human IL-6 infusion (rhIL-6) or saline infusion. In muscle, IL-6 mRNA increased (p<0.05) immediately after exercise, peaking at this time-point, whereas IL-6 mRNA in adipose tissue increased 1.5-h post exercise (p<0.05) displaying a different kinetic of induction. During rhIL-6 infusion, IL-6 mRNA increased 120-fold in muscle (p<0.05). In conclusion, the present study demonstrates that muscle IL-6 is regulated by an autocrine mechanism at the transcriptional level.
authors.affiliation: Department of Infectious Diseases, The Copenhagen Muscle Research Centre, Rigshospitalet, University Hospital of Copenhagen, Blegdamsvej 3, 2100-DK, Denmark.
authors.forename: Pernille
authors.initials: P
authors.lastname: Keller
authors.forename: Charlotte
authors.initials: C
authors.lastname: Keller
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Carey
authors.forename: Sune
authors.initials: S
authors.lastname: Jauffred
authors.forename: Christian P
authors.initials: CP
authors.lastname: Fischer
authors.forename: Adam
authors.initials: A
authors.lastname: Steensberg
authors.forename: Bente K
authors.initials: BK
authors.lastname: Pedersen
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000328:Adult; D019898:Autocrine Communication; D005786:Gene Expression Regulation; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis
chemical_list: D015850:Interleukin-6; D012333:RNA, Messenger