Matrix metalloproteinases in skeletal muscles: Friends or foes?

Matrix metalloproteinases (MMPs) are members of an enzyme family that require a zinc ion at their active site. Active at neutral pH, they catalyze normal turnover of extracellular matrix (ECM) and are critical for maintaining tissue allostasis. Subtle coordination between MMP activity and its inhibition by tissue inhibitors of metalloproteinases (TIMPs) insures ECM homeostasis. Loss of control of MMPs expression/activity in numerous pathologies usually associates with host response to injuries, facilitation of disease progression and significant tissue damage. In skeletal muscles, fragmentary knowledge of MMPs/TIMPs regulation and function underscores the need for a better understanding of their role which may lead to therapeutic alternatives. This review presents the current knowledge of MMPs in the biology and pathology of skeletal muscles and puts into perspective therapeutic alternatives that could be challenged in experimental models or that might emerge from in depth investigation of MMPs/TIMPs status in neuromuscular diseases.