MyD88在鼠衣原体生殖道感染过程中的作用

The Roles of MyD88 in the Development of Protective Immunity and Pathology During Chlamydial Urogenital Infection in Mice

摘要:

用1× 104 IFUs的MoPn经生殖道感染WT、MyD88 KO小鼠, 每组一半小鼠于感染后54 d, 再次感染相同剂量的MoPn。每隔3-4 d取生殖道分泌物, 测定其中衣原体包涵体的数量。初次感染后80 d, 处死小鼠, 眼眶取血, 分离血清, 用间接免疫荧光法测其中抗体类型及效价; 同时分离生殖道, 肉眼观察其输卵管、子宫角水肿程度, 并做病理切片观察其炎症反应; 分离小鼠脾细胞, 体外用衣原体EB刺激, 测定产生的IL-4、IL-5、IL-17和IFN-γ等细胞因子水平。MyD88 KO小鼠阴道带菌时间与WT组相当, 但上生殖道病理反应, 尤其是输卵管水肿程度明显比WT组严重。脾细胞细胞因子水平显示, MyD88 KO鼠IFN-γ和IL-17的产生量明显比WT组低, 而IL-4和IL-5水平明显高于WT组。血清中各亚类抗体效价无明显区别, 但MyD88 KO鼠血清IgG2a/IgG1比值< 1, 且明显低于WT组。研究结果说明MyD88与抗衣原体免疫无关, 但与衣原体引起的炎症损伤密切相关。

Abstract:

C57BL/6J WT and mice deficient in MyD88 (MyD88 KO) were inoculated intravaginally with 1 × 104 IFUs of live C. muridarum organisms. Half mice of each group were reinfected on day 54 after primary infection. Vaginal swabs were taken every 3 or 4 days to monitor live organism shedding. On day 80 after the primary infection, mice were sacrificed, and the vaginal tract was isolated for pathology. The spleen cells were collected and IL-4, IL-5, IL-17 and IFN-γ were detected by ELISA in the spleen cells culture supernatant after restimulated by MoPn EB. The titers of different Ab isotypes were measured in mice serum by Indirect Immunofluorescence Assay. The Chlamydia shedding time of MyD88 KO mice was similar to WT. Not only the gross appearance of the isolated genital tracts, but also the dilation and inflammation scores under microscope showed that the genital tract pathology from the MyD88-deficient mice was much more severe than WT after primary infection. The results of Th2 (IL-4 & IL-5), Th1 (IFN-γ) and Th17 (IL-17) cytokines from the in vitro restimulated splenocyte culture supernatant showed that MyD88 deficient mice produced significantly lower levels of IFN-γ and IL-17 but much higher levels of IL-4 and IL-5 than WT mice either after the primary infection or reinfection with Chlamydia. There were no significant differences in Ab isotype levels between the two tested groups. However, the ratio of MoPn specific serum IgG2a/IgG1 in MyD88-deficient mice was less than 1 and significantly lower than that in WT mice. MyD88 is dispensable for protective immunity but required for inflammatory pathologies.