The Role Of Triggering Receptor On Myeloid Cells-1 In The Pathogenesis Of Acute Viral Myocarditis And Its Mechanism

Background:Myocarditis is a cardiac disease associated with inflammation and injury of the myocardium. The observed pathology in viral myocarditis is a result of cooperation or teamwork between viral processes and host immune responses at various stages of disease. Both innate and adaptive immune responses are crucial determinants of the severity of myocardial damage, and contribute to the development of chronic myocarditis and dilated cardiomyopathy following acute viral myocarditis. Virus induced a lot of cytokines release from inflammatory cell, including IFN, IL and TNF, which play important roles in the pathogenesis of viral myocarditis. Therefore, to reveal the pathological mechanism of viral myocarditis and elucidate relationship with inflammation and immunity reaction is becoming hot spot. We will go further to approach the treatment of viral myocarditis focus on immunity and inflammation.PartIEstablishment of acute viral myocarditis model on murineObjective:To establish a murine model of acute viral myocarditis induced coxsackievirus B3 infection.Methods:Four-week-old male BALB/c mice were inoculated intraperitoneally with 0.3ml coxsackievirus B3 (group A, n=40) to induce myocarditis model, another group were injected with Eagle solution (group B, n=10) as control. Animals were killed at day 0,3,5,7,14 and 28. Myocardial histopathology changes of both groups were observed.Result:in VMC group, pathological examination showed inflammatory cell infiltrate and necrosis of the myocytes.Conclusion:Established the experimental model of viral myocarditis in murine, successfully. Part IIThe role of triggering receptor expressed on myeloid cells-1 in the pathogenesis of acute viral myocarditis induced by CVB3Objective:To study TREM-1,MyD88 expression in the heart of mice after exposure to coxsackievirus B3.Methods:80 Balb/c mice were randomly divided into two groups:Eagle solution group (mice were inoculated Eagle solution)(n=20), VMC group (mice were inoculated intraperitoneally with 0.3ml CVB3) (n=60), Myocardial histopathology changes of all groups were observed. Levles of TREM-1,IL-1 an TNF mRNA on myocardium were measured by PCR; TREM-1 and MyD88 protein levels were determined by west-blotting; the cardiac function were determined by high frequency enchocardiography; and the myocytes apoptosis were assessed by Tunnel technology.Result:We found the mRNA or protein levels of TREM-1,TNF,IL-landMyD88 were significantly increased in the heart of VMC mice induced by coxsackievirus B3. In VMC group, it showed a significant increase of inflammation and myocytes apoptosis, accompanied by decrease of cardiac function.Conclusion:The increase of TREM-1,MyD88,TNF and IL-1 expression may be contributed to the severity of inflammation. And we speculate that TREM-1 and MyD88 may play important roles in the pathogenesis of viral myocarditis. Part IIIThe protective Effect of LP-17 on murine acute myocarditis induced by coxsackievirus B3Objective:To study the effects of LP-17 in a murine model of viral myocarditis induced by coxsackievirus B3 infection.Methods:Four-week-old male Balb/c mice were inoculated intraperitoneally with 0.3ml coxsackievirus B3 on day 0 to induce myocarditis model, and then them are randomly divided into viral myocarditis group (n=25), LP-17 treatment group(at day 3,5, the mouse were inoculated intraperitoneally 200μg LP-17, n=25). The rest were injected with Eagle solution (normal group, n=10) or LP-17 (toxicity test group, n=10) as control. All animals were killed on day 7. Myocardium TREM-1,TNF-α,IL-1mRNA were measured by PCR, changes of serum TNF-α,and IL-1 were assayed by ELISA technology, myocardium TREM-1 and MyD88 protein expression were determined by west-blotting method. The cardiac function were assesed by high frequency enchocardiography,and the myocytes apoptosis were assessed by Tunel technology.Results:Compared with BALB/c controls, the inflammation in LP-17 treatment mice heart was decreased. In the LP-17 treatment group, the mRNA expression of TNF-a, IL-1 and its serum concentration were decreased, accompanied by the decrease of MyD88 protein levels and the number of cell apoptosis. Moreover, LP-17 can restore the cardiac function decrease induced by CVB3.Conclusion:LP-17 has beneficial effect on the murine model of viral myocarditis induced by coxsackie virus B3 for its reducing the inflammation of the heart and decreasing cytokines expression.