CD4+T记忆细胞在哮喘慢性炎症维持中的作用及机制研究

Memory T cells exist in human asthma and asthma animal models.Tcm(Central memory T cell) circulate in peripheral blood,Trm(Resident memory T cells) locate in lung.Our previous research demonstrated the number of Tcm in asthma was more than that in healthy control.STATs (Signal transduction and activator transcription )ratio was imbalance in asthma. It was found STAT1/STAT6 phosphorylation was lower in asthma compared with healthy control.It was interesting that STAT1/STAT6 imbalance was limited to memory T cells,not na?ve T cells.SOCS3(Suppressor of cytokine signals 3) konck-down could make the balance normalization.In this project, we focus on "SOCS3-STATs axis",try to explore the STAT1/STAT6 phosphorylation balance in human blood Tcm and mice lung Trm and the relationship with Tm polarization, proliferation,apoptosis,cytokine profiles.Tm with SOCS3 pre-knock-down is going to infuse back to recipient mice and study how it affect on the number of Tcm,Trm,the phenotype,genotype of Tm and airway inflammation.In this stugy we shed light on the important role of CD4+T memory cells in maintainence of chronic inflammation in asthma,thus provide new way to develop durg or therapy for asthma control.

已知人类和动物哮喘中存在记忆性T细胞（Tm）。中枢性记忆T细胞（Tcm）分布于外周血，肺特异性记忆T细胞（Trm）位于气道。我们前期研究表明，哮喘病人外周血CD4+T记忆细胞比例远高于正常人，且细胞内"信号转导、转录激活子（STATs）"的亚型间比值失衡，即STAT1/STAT6磷酸化比值较正常人降低。有趣的是,该失衡仅见于记忆性T细胞，而非初始细胞。沉默SOCS3(细胞因子信号抑制子3)可使比值趋于正常。因此，本研究以"SOCS3-STATs轴"为主线，深入探索Tcm（人血标本）和Trm（小鼠哮喘模型）的STAT1/STAT6磷酸化功能状态，及其对Tm分化、增殖和凋亡、细胞因子释放的影响。利用基因沉默法体外改造Tm并回输至受鼠，观察对Tcm，Trm构成池、表型、基因型的影响及其对小鼠气道炎症的改善。力求阐释CD4+T记忆细胞在哮喘慢性炎症维持中的重要作用，为开发哮喘新型控制疗法提供新思路

通过该项目支持，发现哮喘患者外周血单个核细胞（PBMC）的记忆T细胞比例升高，以中枢性记忆T细胞为主（而不是效应记忆T细胞）。它以分泌IL-5/IL-17为主，该细胞因子谱与慢阻肺及健康对照者明显不同，说明通过记忆T细胞的细胞因子谱分型有利于鉴别哮喘和慢阻肺。IL-17+CD4+记忆T细胞水平与哮喘的疾病严重程度及用药疾病具有相关性。髓系细胞（包括单核细胞，中性粒细胞和巨噬细胞）的SOCS3条件性敲除后，用OVA刺激，发现会增强气道周围炎症细胞浸润及粘液分泌，SOCS3-/-DC与记忆T细胞（Tm）细胞共培养发现，可增强记忆T细胞的增殖能力及促进释放IFN-r。因此我们认为虽然SOCS3基因敲除不利于减轻哮喘过敏性炎症，但该基因敲除鼠的建立可用于免疫炎症发病机制参与的肺部疾病研究（例如急性肺损伤，肺纤维化等）。SOCS3-/-DC过继给OVA刺激的受鼠可明显降低哮喘小鼠气道炎性细胞的浸润及粘液分泌，降低Eos和IgE的水平，该效应是通过影响了肺免疫细胞IL-10, TGF-b分泌及使细胞内信号转导因子STAT4/STAT6的磷酸化水平受抑制而介导的。