Mechanism of myelin breakdown in experimental demyelination: A putative role for calpain

Although calpain has been extensively studied, its physiological function i s poorly understood. In contrast, its role in the pathophysiology of variou s diseases has been implicated, including that of experimental allergic enc ephalomyelitis (EAE), an animal model of the demyelinating disease multiple sclerosis (MS). In EAE, calpain degrades myelin proteins, including myelin basic protein (MBP), suggesting a role for calpain in the breakdown of mye lin in this disease. Subsequent studies revealed increased calpain activity and expression in the glial and inflammatory cells concomitant with loss o f axon and myelin proteins. This suggested a crucial role for calpain in de myelinating diseases.