CD244在结核病患者CD4+T细胞免疫功能异常中的作用及机制

It is found that the differentiation and function of CD4+ T cells in active TB patients are abnormal, however,the regulating mechanisms are yet to be elucidated. In our previous study of antigen-specific CD4+ T-cells, we found that the expression of CD244 was significantly higher in patients with active TB than latent infection individuals. CD244 inhibited the production of IFN-γ of CD4+ T cells in active TB. CD244 was positive correlated with T-bet,the transcription factor that regulates CD4+ T cell differentiation. We speculate that CD244 involves in regulating CD4+ T cell differentiation and function in active TB patients. In this proposal, we plan to compare the expression of CD244 expression in CD4+ T cell subsets (Th1, Th2, Th17, Treg, etc.) in active TB patients and latent infection individuals, in order to understant the relationship of CD244 expression with progress and outcome of TB; to study the role of CD244 in production of effector molecules IFN-γ, IL-4, IL -17 , IL-10, TGF-β and granulysin; to study the role of CD244 in regulating differentiation, proliferation and apoptosis of antigen-specific CD4+ T cell; To study the signaling pathways of CD244 in regulating functions of CD4+ T cell in active TB. This study may lead to better understanding of TB pathogenesis and has important implication on TB treatment and prevention.

活动性结核病患者CD4+T细胞分化和功能存在异常，但其调控的分子机制还有待深入研究。我们前期的研究发现，CD244在肺结核患者的抗原特异性CD4+T细胞表达显著高于潜伏感染者，可抑制CD4+T细胞IFN-γ产生，且与调控CD4+T细胞分化的转录因子T-bet表达成正相关。我们推测CD244参与调控活动性肺结核CD4+T细胞的分化和功能。本申请计划研究CD244在CD4+T细胞亚群（Th1、Th2、Th17、Treg等）的表达特点及其与结核病的发病和转归的关系；研究CD244在效应分子IFN-γ、IL-4、IL-17、IL-10、TGF-β、Granulysin等产生中的作用；研究CD244与抗原特异性CD4+T细胞分化、增殖和凋亡的关系；研究CD244调控CD4+T细胞功能的信号通路。本研究对进一步阐明结核病患者免疫异常的分子机制及探索结核病防治新途径有重要意义。

本课题研究活动性肺结核患者CD4+T细胞功能异常的分子机制，发现活动性结核病患者结核抗原特异性CD4+T细胞内T-bet的表达显著高于健康对照组（P＜0.0001）；在结核抗原特异性CD4+T细胞中T-bet+细胞中TEM比例显著升高（P＜0.01），TCM比例显著降低（P=0.003）；结核抗原特异性CD4+细胞表面PD-1的表达水平显著高于健康对照组（P=0.006）；T-bet+细胞表面PD-1表达显著高于T-bet-细胞（P=0.0001）；这些结果提示T-bet与TCM的分化相关并可能促进PD-1的表达。本课题在研究CD244在各个细胞亚群的表达发现一群CD244high细胞，用流式细胞术对这一群细胞表型进行分析发现其表型为CD3-CD19-CD56-CD66b-CD33+ CD11b+CD14-HLA-DRneg/low，这与此前报道的人类髓系来源抑制细胞的表型一致。活动性肺结核患者CD244high细胞的比例显著性高于健康对照组（P=0.001），其细胞内NOS表达较高，同时与CD4+和CD8+ T细胞的活化和效应分子的产生呈负相关。本研究对了解结核病患者免疫功能异常机制具有重要意义。