幽门螺杆菌(H.pylori)感染可激发机体免疫反应，但未能有效清除病原，导致相关胃肠疾病发生。现已证明CD4+ T细胞在抗H.pylori感染应答中发挥重要作用，但具体保护作用与机制不清。本课题前期研究发现：H.pylori感染可引起人和小鼠Th9/IL-9应答，并伴随Th17应答升高，而在IL-9敲除后小鼠胃粘膜H.pylori定植量显著增加，Th17应答随之明显降低，结果提示：Th9/IL-9可能调控Th17应答发挥抗H.pylori感染的免疫协同保护作用，但应答机制不清。本课题将以野生型小鼠、IL-9敲除小鼠和Rag1-/-小鼠为模型，采用基因缺失、免疫增强与回复、抗体阻断、免疫过继等技术，探讨Th9/IL-9与Th17应答的协同保护效应和免疫调控的分子机制，将为深入认识CD4+ T细胞抗H.pylori感染的复杂免疫作用机制提供新的解释，为其免疫防治提供理论依据和疫苗设计策略。

Helicobacter pylori(H. pylori) infection can induce immune response, but bacterium can not be cleaned in stomach tissue. Chronic infection of H. pylori lead to associated gastroenterological disease. Though previous research confirmed that traditional CD4+ T- cell played a role in these responses against H. pylori infection, the complex mechanism of protective responses against H. pylori infection remained unclear up to date. In our previous studies, we investigated responses characteristics of different CD4+ T cells subsets in human and mice with H. pylori infection, and found that the response level of Th9 cell which secreted IL-9 increased in H.pylori-infected individual and mice along with Th17 cell responses. In our further IL-9 knockout mice experiment with H. pylori challenge, amount of H. pylori clone in stomach tissue significantly increased compared with wild-type mice postchallenge. Furthermore, Th17 cell responses obviously decreased after IL-9 gene deletion. Above results showed that Th9/IL-9 may play a synergistic protective role with Th17 cell response against H. pylori infection, but these mechanisms of synergistic responses and immunoregulation to Th17 cell were unclear. In current study, these immunological methods, such as immune enhance, Immunological recovery, antibody blocking test and adoptive immunity test, were used to investigate the synergistic effect of Th9/IL-9 with Th17 responses against H. pylori infection and mechanism of immune regulation to specific Th17 cell response in H. pylori infection in wild-type mice, IL-9-/- knockout mice and Rag1-/- mice model. This research will be helpful to further understand the immunological mechanism of CD4+ T cell responses against H. pylori infection. Otherwise, these mechanism of CD4+ T cell responses will also provide theory support to immunological control of H. pylori infection and development of H. pylori vaccine.