Toll-like receptor 3 signaling pathway plays an important role in cardiomyocyte apoptosis and inflammatory response in human viral myocarditis

AIM：To investigate the role of the signaling pathway mediated by Toll-like receptor 3 (TLR3) in cardiomyocyte apoptosis and inflammatory response in human viral myocarditis (VMC). METHODS：The expression of TLR3, TIR domain-containing adaptor inducing IFN-β(TRIF), NF-κB and casepase-3 in myocardial tissues was examined by the method of immunohistochemistry with SP staining, and the apoptosis of cardiomyocytes was detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL). The differences between VMC and control groups were analyzed. RESULTS： Compared with control group, the expression of TLR3, TRIF, NF-κB and casepase-3, and the apoptotic index in VMC group increased remarkably (P<0.05). The positive correlations between TLR3 and TRIF, between TLR3 and NF-κB, between TRIF and NF-κB, and between NF-κB and caspase-3 were observed. The change of the apoptotic index was in accordance with that of caspase-3. CONCLUSION：Inflammatory response and apoptosis mediated by TLR3 play an important role in the genesis and development of viral myocarditis．