[Myokines - muscle tissue hormones]

Physical inactivity is demonstrably related to the manifestation of chronic diseases which significantly modify the quality and prognosis of life in a negative way. The benefits of exercise are surely mediated by many pathophysiological mechanisms interrelated in varying degrees, which have not yet been fully examined in their complexity. In the late 20th century it was positively proven that a working striated muscle really regulates the metabolic and physiological response in the other organs. These involve several hundred substances with autocrine, paracrine and endocrine effects. These proteins and peptides, if released into the blood stream, substantially affect the metabolism of distant organs. They were classified as "myokines" (cytokines produced by myocytes). The identified myokines include e.g. IL4, IL6, IL7, IL15, myostatin, LIF (leukemia inhibitory factor), BDNF (brain-derived neurotrophic factor), IGF1 (insulin-like growth factor), FGF2 (fibroblast growth factor 2), FGF21, FSTL1 (follistatin-related protein 1), irisin, EPO (erythropoetin) and BAIBA (β-aminoisobutyric acid). Myokines have first of all an immunoregulatory role in the human body. Another important effect of myokines is, coincidentally also in the interaction with adipose tissue, the regulation of energy homeostasis. They also affect the growth of muscle fibres and their regeneration, stimulate angiogenesis, they are involved in the regulation of glucose metabolism and have a proven effect on lipids. Considering their diverse function, myokines present a prospective therapeutic goal in the treatment of disorders of muscle growth and regeneration as well as obesity. Another recent research moves toward uncovering of the "myokine resistance" as a result of long-term muscle inactivity and its association with chronic subclinical inflammation.