Effect of myokines on bone tissue metabolism: a systematic review

Myokines are cytokines secreted by skeletal muscle cells. These are cytokines with pleiotropic effects, which have receptors in different organs. Increased secretion of myokines is closely linked to physical activity, through which they affect metabolic processes, signalling pathways, protein expression or cell differentiation. This study aimed to demonstrate the possible impact of myokines on bone tissue metabolism based on a review of published scientific papers and to disseminate knowledge on myokines among the clinician community. To carry out an analysis in accordance with the PRISMA guidelines, publications were searched in PubMed, Web of Science and ScienceDirect databases. Out of the total of 644 papers identified in the databases, 18 original studies were analysed. The paper outlined the importance of irisin, myostatin, fibroblast growth factor 2, myonectin, and interleukins 6 and 15 in the regulation of bone tissue metabolism. Based on the reviewed studies, irisin consistently demonstrates a pro-osteoblastic effect via the p38 MAPK pathway, while myostatin generally shows an inhibitory effect on bone formation by decreasing muscle mass. Myonectin exhibits a dual role, inhibiting both osteoblast and osteoclast differentiation in murine models, suggesting a complex regulatory function. This analysis considers both pre-clinical studies on cell cultures and animal models, as well as clinical trials in humans. The findings suggest that further research is needed to fully elucidate the in vivo functions and clinical relevance of myokines in bone metabolism, identifying potential therapeutic targets.