Cytokines in muscle damage.

Multiple cellular and molecular processes are rapidly activated following skeletal muscle damage to restore normal muscle structure and function. These processes typically involve an inflammatory response and potentially the consequent occurrence of secondary damage before their resolution and the completion of muscle repair or regeneration. The overall outcome of the inflammatory process is potentially divergent, with the induction of prolonged inflammation and further muscle damage, or its active termination and the promotion of muscle repair and regeneration. The final, detrimental, or beneficial effect of the inflammatory response on muscle repair is influenced by specific interactions between inflammatory and muscle cell-derived cytokines that act as positive and/or negative regulators to coordinate local and systemic inflammatory-related events and modulate muscle repair process. A crucial balance between proinflammatory and anti-inflammatory cytokines appears to attenuate an excessive inflammatory reaction, prevent the development of muscle fibrosis, and adequately promote the regenerative process. In this review, we address the interactive cytokine responses following muscle damage, in the context of induction and progression, or resolution of muscle inflammation and the promotion of muscle repair.