ABSTRACT
Objective To investigate the effect of CTLA4-Ig chimera protein on mice mortality, histopathological changes, viral fiters, expression of CTLA4 protein on infiltrated T lymphocyte and the balance of Thl/Th2 in mice myocarditis caused by coxsackie virus B3 (CVB3). Methods A total of 106 four to six week-old male BALB/c mice were used in the experiments, which were divided into CTLA4-Ig 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 CTLA4-Ig group were inoculated intraperitoneally with 0. 15 ml CVB3 and the mice in norreal control group with 0. 15 ml Eagle. The mice in IgG group and CTLA4-1g group were inoculated with IgG (0. I mg/kg) and CTLA4-Ig(0. 1 mg/kg) at 6 h and 72 h post inoculation(p, i. ), respectively, The surplus mice in each group were sacrificed at day 7 p.i. Light microscope was used to quantify the inflammation. The expression of CVB3 mRNA in mycardium were semi-quantified by real-time quantitative polymerase chain reaction (RQ-PCR). The expression of CTLA4 protein were analyzed by immunohistochemistry. The levels of IL-2, IL-4 and 1FN-γ in serum were measured by ELISA. Results The mice mortality, histopathological score and CVB3 mRNA in CTLA4-Ig group were lower than that in CVB3 group ( P < 0.05, P < 0.01, P < 0. 05, respectively). The expression of CTLA4 was significantly increased in CTLA4-Ig therapy group (P < 0.05 ). The serum level of IFN-γ of mice in CVB3 group were significantly higher than that in normal control group( P < 0.01 ). The serum level of IL-4 of mice in CVB3 group were much lower than that in normal control group( P < 0.01 ). The serum level of IL-2 in CVB3 group had no statistical significance with that in normal control group ( P > 0.05 ). The serum level of IFN-γ in mice of CTLA4-Ig group were much lower than that in CVB3 group ( P <0.01 ) and lgG group (P < 0. 01 ). The serum level of IL-4 of mice in CTLA4-Ig group were significantly higher than that in CVB3 group (P<0.01) and IgG group (P<0.01). The serum level of IL-2 in CTLA4-Ig group had no statistical significance with that in CVB 3 control group and lgG group ( P > 0. 0 5 ) . Conclusion CTLA4-Ig may relieve inflammation and reduce mice mortality by blocking the costimulation signals for T lymphocyte activation and reinforcing Th2 response.