APOPTOTIC CELL DEATH OF CARDIOMYOCYTES IN VARIOUS HEART DISEASES

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There exist two general types of cell death, necrosis and apoptosis, marked by different morphological and molecular characteristics. The mechanism of the cardiomyocyte dath has been classicaly believed to be necrosis in various heart diseases. Therefore, we examined whether apoptotic cardiomyocyte death occurs in acute fulminant myocarditis and scute myocardial infarction and if so, whether the Fas (CD95)/Fas ligand system is associated with the apoptosis. Nucleosomal DNA fragmentation, the biologic hallmark of apoptosis, was detected in numerous cardiomyocytes of these diseases. The expression of Fas antigen protein was upregulated in some of cardiomyocytes, but not in the control. In myocarditis, the expression Fas ligand mRNA and protein was expressed in some of CD4+and CD8+ T cells. Co-expression of Fas and Fas-L was observed in some infiltrating lymphocytes. These results indicate that there exist apoptotic death of the affected cardiomyocytes and infiltrating lymphocytes in acute fulminant myocarditis and myocardial infarction. It is likely that the apoptosis of cardiomyocytes might be associated with the Fas/Fas-ligand pathway.