Immunomodulation and matrix metalloproteinases in viral myocarditis

Myocarditis is an inflammatory disorder induced most commonly by infectious agents. The natural course of the disease is broad and ranges from complete recovery to dilated cardiomyopathy and death. The mechanisms of the incomplete recovery remain poorly understood but extracellular matrix remodelling by metalloproteinases seems to be important for the progression to dilated cardiomyopathy and chronic heart failure. The matrix metalloproteinases (MMPs) are proteolytic enzymes whose role was thought to be the degradation of matrix components only. In the last few years a considerable amount of evidence has gathered which shows new functions of the MMPs as powerful modulatory factors in inflammatory disorders. MMPs facilitate the migration of immune cells through the basement membrane, process cytokines and chemokines by modulating their function, and regulate the relationship of cells with ECM components. These findings enhance our knowledge of the role of MMPs in viral myocarditis and inflammatory cardiomyopathy and may lead to a new understanding which might allow for specific and successful therapeutic interventions in the future.