The Therapeutic Role Of CD28 MAb And Its Influence On The Balance Of Th1/Th2 In Murine Viral Myocarditis

ObjectivesThis study was sought to investigate the effect of CD28 monoclonal antibody (CD28mAb) and its influence on the balance of Th1/Th2 in murine viral myocarditis induced by Coxsackievirus B3(CVB3).MethodsA total of 106 four to six week old BALB/c male mice were used in the experiments,which were divided into CD28mAb group(n=16),CVB3 group(n=40), IgG group(n=40) and normal control group(n=10) randomly.The mice in CVB3 group,IgG group and CD28mAb group were inoculated intraperitoneally with 0.15ml CVB3(TCID₅₀ 10^-6/ml) and the mice in normal control group with 0.15ml eagle.The mice in IgG group and CD28mAb group were inoculated with IgG(0.1mg/kg) and CD28mAb(0.1mg/kg) on 6 hours and 72 hours post inoculation(p.i.),respectively. The surplus mice in each group were sacrificed on day 7 p.i..The enzyme linked immunosorbent assay(ELISA) was used to measure the concentration of sera IL-2, IFN-γ,IL-4.The heart were removed aseptically,half of each heart was used for hematoxylin and eosin(HE) staining.The myocardial histopathologic scores were determined by optical microscope.Half of each heart was freezed in -80℃refrigerator.The expression of IL-2,IFN-γ,IL-4 and CVB3 mRNA were detected by Real time polymerase chain reaction(RQ-PCR).Results1.The incidence of myocarditis were 100%.There were intensive myocyte degeneration,necrosis and inflammatory cells infiltration in the myocardium of mice inoculated by CVB3.2.The mice mortality in CD28mAb group were lower than that in CVB3 group (50%vs.80%;p＜0.05) and IgG group(50%vs.77.5%;p＜0.05).The histopathologic scores were much lower than that in CVB3 group(5.25±1.91 vs. 8.88±2.95;p＜0.05).3.The expression of CVB3mRNA in CD28mAb group were much lower than CVB3 group(0.51±1.80 vs.3.48±2.89;p＜0.05).4.The serum level of IFN-γof mice in CVB₃ group were significantly higher than that in normal control group(196.30±16.89 vs.26.20±7.61;p＜0.05).The serum level of IL-4 of mice in CVB₃ group were much lower than that in normal control group(50.80±6.04 vs.146.50±21.27;p＜0.05).The serum level of IL-2 in CVB₃ group were nearly as same as that in normal control group(p＞0.05).5.The serum level of IFN-γof mice in CD28mAb group were much lower than that in CVB₃ group(30.38±4.42 vs.196.30±16.89;p＜0.05).The serum level of IL-4 of mice in CD28mAb group were significantly higher than that in CVB₃ group (116.04±31.05 vs.50.80±6.04;p＜0.05).The serum level of IL-2 were nearly as same as that in CVB₃ group(p＞0.05).6.The expression of IFN-γmRNA in myocardium of mice in CVB3 group were significantly higher than that in normal control group(61.29±68.24 vs. 6.61±15.09;p＜0.05).The expression of IL-2 and IL-4 mRNA in myocardium of mice in CVB3 group were no significant difference with normal control group (p＞0.05).7.The expression of IL-4 mRNA in myocardium of mice in CD28mAb group were significantly higher than that in CVB₃ group(137.3±196.38 vs.1.38±1.69; p＜0.05).The expression of IFN-γ,and IL-2 were no significant difference in these groups(p＞0.05).Conclusions1.The peripheral serum level of IFN-γincreased and the serum level of IL-4 decreased significantly.The expression of IFN-γmRNA in myocardium increased. It suggested that the Thl response were predominated during the acute stage of VMC.2.Treatment with CD28mAb reduced the mice mortality,relieved myocardial inflammation and reduced viral replication.It suggested that CD28mAb have therapeutical role in murine viral myocarditis induced by CVB3.3.CD28mAb could decrease of IFN-γlevel and IL-4 level in peripheral serum,and up-regulate IL-4 mRNA in myocardium.It suggested that CD28mAb could decrease Th1 response and reinforce Th2 response and therefore switch the balance of Th1/Th2.