肺炎支原体引起Th细胞分化的信号通路及有效病原成分的研究

In clinical practice, we found that children with mycoplasma pneumoniae infection are often characterized by cough and inspiratory wheeze, and often develop secondary allergic disease. Our previous study showed that when children with mycoplasma pneumoniae infection there are significant increasement in serum IgE levels, and there are Th1/Th2 cytokines imbalances. We want to know the exact signal pathway to work. The existing studies have shown that Jak/STAT signaling pathways regulate the differentiation of Th cells. Hence we infer that mycoplasma pneumoniae infection is through the Jak/STAT signaling pathway to regulate Th0 cell differentiation, and ultimately causes the imbalance of Th1/Th2 cytokines, then induces allergic disease such as asthma. Therefore, this study plans to establish mycoplasma pneumoniae infection model in mice and to use the mycoplasma pneumoniae to co-culture with Naive T cells, then to test key molecules in the signal pathways and cytokine levels to verify the above idea. In addition, this study plans to separate different ingredients of mycoplasma pneumoniae to co-culture with Naive T cells in order to make clear the specific composition which to influence Th cell differentiation. This study is expected to provide hygiene evidence for the hypothesis that mycoplasma pneumoniae can cause asthma and to provide targets for vaccines.

临床上发现肺炎支原体感染的患儿常常表现为咳喘，并且常继发过敏性疾病。我们的一项前期研究表明肺炎支原体感染的患儿血清中IgE水平显著升高，且Th1/Th2类细胞因子发生失衡。已有研究表明Jak/STAT信号通路调控Th细胞的分化。由此我们推断肺炎支原体感染后是通过Jak/STAT信号通路来调节Th0细胞的分化，并最导致Th1/Th2类细胞因子的失衡，引起哮喘等过敏性疾病。因此，本课题拟通过建立肺炎支原体感染的小鼠模型及将肺炎支原体与Naïve T细胞进行共培养，检测信号通路中关键分子以及细胞因子水平的变化来验证上述想法。此外，本课题还拟通过分离肺炎支原体不同的菌体成分与Naïve T细胞进行共培养以明确引起Th细胞分化的有效病原成分。本课题有望为肺炎支原体引起哮喘的发病提供卫生学证据，为疫苗的研制提供靶点。

1970年，Berkovich等人首次报道了哮喘发作与肺炎支原体（MP）之间的联系。从那时起，MP感染与哮喘之间的关系成为全球研究人员的关注点之一。越来越多的证据表明MP感染与哮喘发作密切相关，但其确切的机制尚不清楚。我们之前的研究发现，大多数MP肺炎（MPP）患者的血清总IgE水平升高。本项目旨在确定可导致儿童IgE增加的肺炎支原体成分，并阐明其具体机制。我们采用MPP患者血清IgE钓取相应的MP细胞成分。通过原核表达获得的这些组分用作过敏原以检测MPP患者中产生的过敏原特异性IgE的比例，并且还分析了产生该过敏原特异性IgE的这些患者的临床特征和相关免疫参数。此外，细胞实验用于验证这些组分在体外的生物学效应。在MPP儿童血清中检测到P1特异性IgE。 通过镍琼脂糖亲和层析纯化的原核表达获得约24kDa的P1蛋白。经过检测发现大约9.2％的MPP患者产生针对P1蛋白的IgE，且其更可能在没有过敏史或过敏相关疾病家族史的MPP患者中产生。P1特异性IgE阳性MPP患者具有更严重的临床症状，IL-4和IL-5分泌过多以及Th0细胞过度分化为Th2细胞。研究还表明，P1蛋白刺激健康供体外周血中PBMCs中IL-4和IL-5的过量分泌。基于以上研究结果，本研究明确了肺炎支原体的P1蛋白是诱导Th细胞分化及Th1和Th2类细胞因子失衡的病原成分。还阐明了肺炎支原体感染后机体产生P1蛋白特异的IgE抗体是导致肺炎支原体感染引起哮喘发生的重要机制之一。该研究为哮喘发病的卫生学学说提供了直接可靠的证据。明确了肺炎支原体感染引起 Th 细胞分化的有效病原成分，为临床干预提供了方法，为疫苗的研制提供了靶点。