Role of Inflammation and Matrix Proteinases in Cardiac Remodeling Following Stress and Injury

Abstract

Whether the myocardial damage is initially caused by ischemia or viral infection of the heart, a tightly regulated inflammatory response is provoked in an attempt to restore cardiac homeostasis and to preserve its proper function. However, a growing body of evidence suggests that uncontrolled cardiac inflammation—due to mechanisms we do not fully understand—can lead to adverse cardiac remodeling and facilitates the disease progression to its sequelae, dilated cardiomyopathy, congestive heart failure, or even sudden death. Discoveries over the last years have made it clear that an important regulator of the inflammatory pathways may be found in the cardiac extracellular matrix (ECM), known as the matrix metalloproteinase (MMP) system. It is now becoming clear that degradation and turnover of the cardiac ECM is neither the sole nor the main function of these proteinases. In fact, a growing body of evidence suggests that a complex bidirectional cross talk exists between the MMP system and a wide variety of cytokines, chemokines, growth factors, and other bioactive molecules that regulates diverse and sometimes opposing aspects of the inflammatory response in the injured heart. Furthermore, the use of single MMP-mutant mice seems to indicate MMP inhibition as potentially cardioprotective after myocardial infarction while detrimental during the pathogenesis of coxsackievirus B3-induced viral myocarditis. These findings enhance our knowledge in the MMP field and in that of inflammatory cardiomyopathy and will without a doubt allow for novel and highly specific therapeutic interventions in the future.