系统性尖端赛多孢感染小鼠干扰素γ表达的研究

目的 了解系统性尖端赛多孢感染小鼠干扰素γ(IFN-γ)的表达特征,探讨IFN-γ在系统性尖端赛多孢感染中所起的作用.方法 建立小鼠系统性尖端赛多孢感染模型,用酶联免疫吸附试验及逆转录-聚合酶链反应分别检测脾内IFN-γ蛋白质及mRNA水平,用平皿系列稀释法检测肾内菌落形成单位(cfu),并记录平均生存时间.结果 IFN-γ的表达:正常组为0.430±0.148(IFN-γ/G₃PDH,下同),致死量组第3天为0.211±0.124,第7天为0.386±0.180,均低于正常组,但两组比较,第3天P<0.05,第7天P>0.05;亚致死量组第3天为0.705±0.206,第7天为0.895±0.101,均高于正常组,两组比较第3天P<0.05,第7天P<0.01,且7d与3d比较P<0.01;免疫抑制组第3天为0.221±0.127,第7天为0.470±0.223,第3天结果低于正常组,两组比较第3天P<0.05,第7天P>0.05.此外,免疫抑制组均低于相应时间亚致死量组(第3天、第7天均P<0.01).肾内带菌量:致死量感染组第3天为(15.32±2.44)×10²cfu,第7天为(78.58±19.97)×10²cfu;免疫抑制组第3天为(10.16±1.52)×10²cfu,第7天为(65.72±18.64)×10²cfu;亚致死量组第3天为(5.51±1.66)×10²cfu,第7天为(1.29±0.49)1×10²cfu,致死量感染组及免疫抑制组肾内均有大量菌生长,亚致死量组肾内菌量较少.平均生存时间:致死量感染组平均13.6d死亡,免疫抑制组平均14.2d死亡,对照组和亚致死量组生存时间均超过45d.结论 健康鼠大量菌感染及免疫抑制鼠少量菌感染均可引起致死性感染,而IFN-γ在小鼠系统性尖端赛多孢感染中可能具有保护作用.

Study on the Expression of Interferon-gamma in Experimental Murine Systemic Scedosporum Apiospermum Infection

Objective To study the expression and the role of interferon-gamma (IFN-γ)in murine systemic infection of Scedosporum apiospermum. Methods The murine models of systemic Scedosporum apiospermum infection was established by inoculation of the pathogenic fungi. ELISA and RT-PCR were applied to detect the expression level of IFN-γ protein and mRNA in spleens, respectively. Colony formingunit (cfu) of infected kidneys was determined with the plating dilution method. The mean survival time (MST) of the mice was also recorded. Results IFN-γ levels in lethal infection group were lower than those of the normal controls (P<0.05 on day 3 and P > 0.05 on day 7). IFN-γ levels of sublethal infection group were higher than those of normal controls (P<0.05 on day 3 and P<0.01 on day 7). IFN-γ levels of dexa-methasone-immunosuppressed group were lower than those of the normal group (P<0.05 on day 3 and P>0.05 on day 7). But the IFN-γ levels were significantly lower in the immunosuppressed group than those in the sublethal infection group (P<0.01 on day 3 and day 7). Fungal loads in the kidneys showed that there were a large amount of fungi in kidneys in both the lethal infection group and the immunosuppressed group, while only a few fungi in the sublethal infection group. The MST was 13.6 days and 14.2 days in the lethal infection group and the immunosuppressed group respectively, while it was more than 45 days in both the normal controls and the sublethal infection group. Conclusions The large dosage inoculation of Scedosporum apiospermum in normal mice and small amount of the fungi inoculation in the dexamethasone-immunosuppressed mice lead to the lethal infection. It suggests that IFN-γ might play a protective role in the murine systemic infection of Scedosporum apiospermum.