Research on expression of granzyme B in myocardium with experimental viral myocarditis
Objective To explore the role of granzyme B( GzmB) in infiltrated myocardial cells of mice with viral myocarditis( VMC) induced by coxsackievirus B3(CVB3) during the injury of myocardium and further to elucidate the pathogenesis of VMC. Methods Thirty-six BALB/c male mice, 5 to 6 weeks old, were randomly divided into two groups: the normal group, 10, and the model group, 26. On the eleventh day all mice were killed and the hearts were taken out for inspection whether there were pathological changes in the myocardium by macroscopy and microscopy. The expression of GzmB was detected in myocardium with immunohistochemistry and hemi-quantitive reverse transcript-polymerase chain reaction ( RT-PCR). Results GzmB positive cells in the mice myocardial cells infiltrated were detected by immunohistochemistry in the model group,and the number of GzmB positive cells is remarkable positive correlation to myocardial pathological score(r =0. 859, P =0.000) , however, no such cells were discovered in the normal murine hearts. Test of RT-PCR showed markedly high expression of GzmB mRNA in mice myocardium of the model group, however, no expression of GzmB mRNA in the normal group. Conclusion The expression of GzmB in the infiltrating myocardiocytes probably plays some role during the injury of myocardium, which mediated cytotoxicity effect is one of important mechanisms of myocardial injury in viral myocarditis. The expression quantity of GzmB in the infiltrating myocardiocytes is significant positive correlation to the severity of myocardial injury. 
 
Key words: 
Viral myocarditis;  T lymphocytes;  cytotoxic;  Killer cells;  Granzyme B