高通量测序分析实验性脑脊髓炎肠道微生物变化及与IL-17、IFN-γ相关性

Correlation of gut microbiota with IL-17 and IFN-γ in experimental autoimmune encephalomyelitis

摘要:

[目的]通过建立实验性脑脊髓膜炎（EAE）小鼠模型，观察小鼠肠道菌群在不同发病时间点的变化和炎症因子IL-17、IFN-γ的表达情况，探讨肠道菌群的变化在EAE发病中的免疫调节作用。[方法]将48只C57BL/6小鼠按照随机数字表法分为正常对照组、EAE模型组各24只。EAE组采用MOG_35-55与完全弗氏佐剂的混合物制备模型，进行神经功能评分，记录体重变化。分别取免疫后7、14、21、30 d的小鼠粪便，对样本DNA的16S rDNA V3/V4区基因测序。ELASE法检测IL-17、IFN-γ的表达。[结果]EAE组小鼠血液中IL-17、IFN-γ的表达从第7天开始逐渐升高，21 d时达到高峰。14 d时，EAE组与正常对照组相比，物种丰度有显著性差异（P<0.05）的菌种有：Alistipes、布牢特氏菌属、毛螺菌科_NK4A136_group等。30 d EAE组与正常对照组相比，物种丰度有显著性差异（P<0.05）的菌种有：Allobaculum、真细菌属、螺杆菌等。通过LefSe分析，在7、14、21 d中分别主要作用的微生物菌种逐渐减少，在21 d时最少。Odoribacter在21 d时起了主要作用。[结论]与正常对照组相比，14、21、30 d EAE小鼠肠道菌种的丰度均发生了变化，产生了肠道菌群的紊乱；其中普雷沃氏菌属_NK3B31_group的丰度均较正常对照组降低，与IFN-γ呈负相关（r=-0.537，P<0.01）。普雷沃氏菌属_NK3B31_group可能是导致MS脱髓鞘发生的关键菌属。EAE组各个时间点相比起主要作用的肠道菌群种类减少，多样性降低。其中，Odoribacter是在21 d高峰期起主要作用的菌种，但其作用机制需要深入研究。EAE组中炎症因子IL-17、IFN-γ表达的升高，促进了MOG_35-55诱发的炎症反应。

Abstract:

[Objective] To explore the immune regulatory effect of gut microbiota in experimental autoimmune encephalomyelitis (EAE), we studied the change of gut microbiota and its correlation with the production of IL-17 and IFN-γ at different times. [Methods] Female C57BL/6 mice were divided randomly into 2 groups:the normal group and EAE. EAE was induced with MOG_35-55 mixed with complete Freund's adjuvant. The weight and neurological scores of 2 groups were observed. The 16S rDNA V3/V4 region of DNA of gut microbiota was indentified by the Illumina Mi Seq high-throughput sequencing.IL-17 and IFN-γ in the blood were detected by ELSIA. [Results] The production of IL-17 and IFN-γ reached the peak on day 21. The abundance of Alistipes, Blautia and Lachnospiraceae_NK4A136_group in EAE were different from the normal group on day 14. However, the abundance of Allobaculum, Eubacterium, Helicobacter were significantly changed on day 30. According to LefSe analysis, the microbial strains that were mainly affected on 7 day, 14 day and 21 day gradually decreased, and dropped the least on 21 day. Odoribacter played an important role on 21 day. Compared with the normal group, the abundance and diversity of gut microbiota in EAE changed. The abundance of Prevotellaceae_NK3B31_group in EAE was lower than the normal group, and related negatively with the production of IFN-γ (r=-0.537, P<0.01). Prevotellaceae_NK3B31_group maybe the key bacteria that caused the demyelination of MS. [Conclusion] The abundance and diversity of gut microbiota played the important role at the different times in the EAE group. The production of IL-17 and IFN-γ leaded to the inflammatory of EAE that induced by MOG_35-55.