Increased interleukin 1β in human skeletal muscle after exercise

Interleukin 1β (IL-1β) is a protein released from blood monocytes and related cells in response to infectious or inflammatory stimuli. Although IL-1β is elevated in the circulation for only a few hours after an acute inflammatory challenge or exercise, it has been proposed to mediate anabolic and catabolic processes that can last for several days. In this report, eccentric exercise was used as a noninfectious inflammatory stimulus. IL-1β was found in muscle tissue up to 5 days after exercise using specific immunohistochemical tissue staining. Increased IL-1β immunoreactivity was observed in muscle tissue from four human subjects who performed the exercise, but not in tissue obtained at the same time intervals from two subjects who did not exercise. Little immunohistochemical evidence of interleukin-1α or tumor necrosis factor α was observed before or after exercise. These results implicate IL-1β in the metabolic adaptations of muscle tissue, which occur in response to noninfectious stresses.