title: Immunohistochemical detection of interleukin-6 in human skeletal muscle fibers following exercise.
abstract: Interleukin-6 (IL-6) is produced by many different cell types. Human skeletal muscles produce and release high amounts of IL-6 during exercise; however, the cell source of origin in the muscle is not known. Therefore, we studied the protein expression of IL-6 by immunohistochemistry in human muscle tissue from biopsies obtained at time points 0, 3, 4.5, 6, 9, and 24 h in relation to 3 h of bicycle exercise performed by healthy young males (n=12) and in resting controls (n=6). The IL-6 expression was clearly increased after exercise and remained high even by 24 h, relative to pre-exercise or resting individuals. The IL-6 immunostainings of skeletal muscle cells were homogeneous and without difference between muscle fiber types. The IL-6 mRNA peaked immediately after the exercise, and, in accordance, the IL-6 protein expression within muscle cells was most pronounced around 3 h post-exercise. However, the finding that plasma IL-6 concentration peaked in the end of exercise indicates a high turnover of muscle-derived IL-6. In conclusion, the finding of marked IL-6 protein expression exclusively within skeletal muscle fibers following exercise demonstrates that skeletal muscle fibers of all types are the dominant cell source of exercise-induced release of IL-6 from working muscle.
authors.affiliation: Department of Infectious Diseases 7641, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark.
authors.forename: Milena
authors.initials: M
authors.lastname: Penkowa
authors.forename: Charlotte
authors.initials: C
authors.lastname: Keller
authors.forename: Pernille
authors.initials: P
authors.lastname: Keller
authors.forename: Sune
authors.initials: S
authors.lastname: Jauffred
authors.forename: Bente Klarlund
authors.initials: BK
authors.lastname: Pedersen
mesh_terms: D015444:Exercise; D006801:Humans; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D008297:Male; D008954:Models, Biological; D018485:Muscle Fibers, Skeletal / Q000737:chemistry* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000737:chemistry* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D015850:Interleukin-6; D012333:RNA, Messenger