title: Skeletal muscle IL-4, IL-4Ralpha, IL-13 and IL-13Ralpha1 expression and response to strength training.
abstract: Interleukin-4 (IL-4) and interleukin-13 (IL-13) are Th2 cytokines involved in various immune responses and only a few reports examine skeletal muscle and the possible role of Th2 cytokines in myoblast fusion and myotube maturation. We hypothesized that IL-4, IL-13 and their receptors are involved in skeletal muscle adaptations to strength training. We investigated the effects of 6 weeks of strength training with different muscle load on IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 expression in skeletal muscle: training with maximal contractions (Max group, n = 12) and training with lower load combined with ballistic and stretch-shortening contractions (Combi group, n = 12). Muscle samples were taken from triceps brachii before and after the 6 weeks of training. mRNA levels of IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 expression were determined by real-time PCR and IL-4 protein expression by ELISA. We demonstrate for the first time that IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 are expressed in skeletal muscle in vivo and are up-regulated after strength training. Higher training load in Max leads to higher cytokine responses, which was significant for IL-4Ralpha though IL-4 protein expression did not change significantly. Although the exact mechanisms have yet to be established, and these results may be preliminary, we speculate that IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 are involved in muscle hypertrophy, MHC-transformation and anti-inflammatory damage control that occur during strength training.
authors.affiliation: Section Sports and Rehabilitation Medicine, Department of Internal Medicine II, University of Ulm, 89075 Ulm, Germany.
authors.forename: Olga
authors.initials: O
authors.lastname: Prokopchuk
authors.forename: Yuefei
authors.initials: Y
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Klaus
authors.initials: K
authors.lastname: Wirth
authors.forename: Dietmar
authors.initials: D
authors.lastname: Schmidtbleicher
authors.forename: Jürgen M
authors.initials: JM
authors.lastname: Steinacker
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D015444:Exercise; D020869:Gene Expression Profiling; D006801:Humans; D018793:Interleukin-13 / Q000235:genetics* / Q000276:immunology; D053661:Interleukin-13 Receptor alpha1 Subunit / Q000235:genetics* / Q000276:immunology; D015847:Interleukin-4 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D053662:Interleukin-4 Receptor alpha Subunit / Q000235:genetics* / Q000276:immunology; D008297:Male; D018482:Muscle, Skeletal / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
chemical_list: D018793:Interleukin-13; D053661:Interleukin-13 Receptor alpha1 Subunit; D053662:Interleukin-4 Receptor alpha Subunit; D012333:RNA, Messenger; D015847:Interleukin-4