Effects of eccentric treadmill exercise on inflammatory gene expression in human skeletal muscle

Abstract

The present study examined the skeletal muscle expression of several genes related to the inflammatory process before and after a bout of downhill running. Twenty-nine males between the ages of 18 and 35 years performed a 45-min downhill (-17.5%) treadmill protocol at 60% of maximal oxygen consumption. Venous bloods samples and muscle biopsy samples from the vastus lateralis were donated prior to and at 3-h and 24-h postexercise, along with ratings of perceived muscle soreness. Serum creatine kinase (CK) was determined, as was skeletal muscle gene expression of interleukin (IL)-6, IL-8, IL-12 (p35), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, cyclooxygenase 2 (COX2), and nuclear factor kappa B (NFkB) (p105/p50). Gene expression was analyzed using RT-PCR and compared with a standard housekeeping gene (beta-actin). Data were analyzed for statistical differences using multivariate analysis of variance with univariate follow-up. In addition, Pearson correlations were conducted to determine if any significant relationship exists between any of these transcripts and both CK and muscle soreness. Significant (p < 0.05) up-regulations in IL-6, IL-8, and COX2 mRNA expression were observed compared with baseline, whereas no significant changes for IL-12, IL-1beta, TNF-alpha, or NFkB were noted. Significant increases in IL-6 mRNA were observed at 3 h (p < 0.001) and 24 h (p = 0.043), whereas significant increases in IL-8 (p = 0.001) and COX2 (p = 0.046) mRNA were observed at 3-h postexercise. In addition, muscle soreness was significantly correlated with IL-8 at 24 h (r = -0.370; p = 0.048), whereas CK was significantly related to NFkB at baseline (r = -0.460; p = 0.012). These data indicate that increases in the mRNA expression of IL-6, IL-8, and COX2 occur in the vastus lateralis as a result of damaging eccentric exercise in young, recreationally trained males. Further, it appears that IL-8 transcription may play some role in inhibiting postexercise muscle soreness, possibly through regulation of angiogenesis.

Oxygen Consumption and Usage During Physical Exercise: The Balance Between Oxidative Stress and ROS-Dependent Adaptive Signaling

“…Recently, it has been suggested that IL-6 acts as an energy sensor, exhibiting local and endocrine metabolic effects (278,279). IL-6 and other cytokines such as IL-8, cyclooxygenase2, and TNF-a are significantly activated after unaccustomed muscle contractions, which cause microdamage to sarcomeres (54,208). The repair of the damage by satellite cells is crucial, as these cells divide and fuse to form myotubes.…”

Age-Related Inflammation: the Contribution of Different Organs, Tissues and Systems. How to Face it for Therapeutic Approaches

“…Indeed, they demonstrated that exercise-deprivation induced a cluster of physiological abnormalities, similar to metabolic syndrome (such as insulin resistance, impaired glucose uptake and hyperlipidemia). Moreover, exercise also significantly alters muscle gene expression [130]. Thus, it has been proposed that active muscle might secrete one or more factors such as myokines that mediate important changes in gene expression.…”

“…One of such factors could be IL-6, despite its well known role in the pro-inflammatory pathways. Muscle contraction directly stimulates release of IL-6, which in turn stimulates sequential release of IL-1ra and IL-10, and trained muscle (i.e., muscle with low glycogen content) releases more IL-6 than untrained muscle [130,131]. Although IL-6 mediates some of the physiological effects of exercise, other factors are likely to play a role in this process, such as TNF-, IL-18 and/or brain-derived neurotrophic factors, thus suggesting that skeletal muscle and specifically physical exercise could be considered as mediators to counteract inflamm-ageing at systemic level [132].…”

Microvascular Perfusion Increases After Eccentric Exercise of the Gastrocnemius

“…Researchers use eccentric exercise as a model for acute inflammation with an assumption that blood flow increases right away as it would in acute injury. 15,16 However, the extent at which blood flow increases, if at all, is unknown.…”