Endurance training enhances skeletal muscle interleukin-15 in human male subjects

• Published in: Endocrine Vol. 45; no. 2; pp. 271 - 278
• Main Authors: Rinnov, Anders, Yfanti, Christina, Nielsen, Søren, Åkerström, Thorbjörn C. A., Peijs, Lone, Zankari, Alaa, Fischer, Christian P., Pedersen, Bente K.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.03.2014
• Subjects: Adaptation, Physiological - physiology; Adult; Biopsy; Diabetes; Endocrinology; Exercise - physiology; Exercise Test; Humanities and Social Sciences; Humans; Interleukin-15 - metabolism; Internal Medicine; Male; Medicine; Medicine & Public Health; multidisciplinary; Muscle, Skeletal - metabolism; Muscle, Skeletal - pathology; Original Article; Physical Endurance - physiology; RNA, Messenger - metabolism; Science; Time Factors; Up-Regulation - physiology; IL-15; Exercise; Endurance training; Skeletal muscle
• ISSN: 1355-008X; 1559-0100; 1559-0100
• DOI: 10.1007/s12020-013-9969-z

Regular endurance exercise promotes metabolic and oxidative changes in skeletal muscle. Overexpression of interleukin-15 (IL-15) in mice exerts similar metabolic changes in muscle as seen with endurance exercise. Muscular IL-15 production has been shown to increase in mice after weeks of regular endurance running. With the present study we aimed to determine if muscular IL-15 production would increase in human male subjects following 12 weeks of endurance training. In two different studies we obtained plasma and muscle biopsies from young healthy subjects performing: (1) 12 weeks of ergometer cycling exercise five times per week with plasma and biopsies before and after the intervention, and (2) 3 h of ergometer cycling exercise with plasma and biopsies before and after the exercise bout and well into recovery. We measured changes in plasma IL-15, muscle IL-15 mRNA and IL-15 protein. Twelve weeks of regular endurance training induced a 40 % increase in basal skeletal muscle IL-15 protein content ( p  < 0.01), but with no changes in either muscle IL-15 mRNA or plasma IL-15 levels. However, an acute bout of 3-h exercise did not show significant changes in muscle IL-15 or plasma IL-15 levels. The induction of muscle IL-15 protein in humans following a regular training period supports previous findings in mice and emphasizes the hypothesis of IL-15 taking part in skeletal muscle adaptation during training.