自噬和凋亡在甲型流感病毒和肺炎球菌协同感染小鼠模型中作用的初探

摘要

Objective To establish an animal model for synergistic infection of Influenza A virus (IAV) and Streptococcus pneumonia (SP) and preliminarily explore the roles of autophagy and apoptosis.Methods Balb/c mice were administered with IAV and/or SP in different sequences.Mortalities were observed.Titers of IAV and SP,pathological changes in the lungs were analyzed at certain time points.The expressions of LC3,Caspase-3 were assayed by immunohistochemical staining.Results Mice infected IAV seven days ahead of SP,compared with those from other groups,ended up with the highest mortality rate and IAV/SP titers 24 hours after the second challenge,they also exhibited the most severe pathological changes 48 hours after the second challenge.Immunochemistry assay showed that the peak of LC3 expression appeared at the early stage of IAV infection followed by a decrease in a time-dependent manner,while Caspase-3 reached the highest expression at the late stage of IAV infection.Conclusions An IAV-SP synergistic infection mouse model has been established.The development of autophagy was earlier than that of apoptosis in this preliminary exploring.Our study has laid a solid foundation for further research on the roles of autophagy and apoptosis in IAV-SP co-infection in vivo,as well as verified our hypothesis that autophagy would occur earlier than apoptosis during the intruding of IAV.%目的 建立甲型流感病毒(Influenza A virus,IAV)和肺炎链球菌(Streptococcus pneumoniae,SP)协同感染小鼠模型,在该模型中初步探索自噬和凋亡的发生情况.方法 将IAV和SP以不同顺序感染Balb/c小鼠,观察其体重变化和死亡率,检测其肺部IAV和SP滴度、病理改变情况,建立IAV ～ SP协同感染动物模型.使用免疫组化法检测自噬特征蛋白LC3及凋亡特征蛋白Caspase-3的表达情况.结果 IAV～SP组第二次感染后24 h时小鼠肺部IAV和SP滴度最高,死亡率也明显高于其他各组,48 h病理改变也最为严重.免疫组化结果显示IAV感染早期(24 h～48 h)LC3蛋白表达出现峰值,Caspase-3缓慢上升;晚期(72 h～96 h)Caspase-3蛋白表达出现峰值,而LC3蛋白表达逐渐下降.结论 本研究成功建立了1AV～ SP协同感染动物模型,模型鼠中自噬先于凋亡发生,为进一步研究自噬和凋亡在IAV～ SP协同感染中的作用奠定了基础.