αβTCR+CD4-CD8- T淋巴细胞在ConA诱导的免疫性肝损伤中的免疫调节机制研究

Liver has peculiar anatomy and microanatomy, unique features of hepatic parenchymal cells and a large number of resident immune and immune-related cells. The liver is also an important site of immune regulation of human body for its ability to balance between immune tolerance and overreaction. Primary (autoimmune liver disease) or secondary (viral hepatitis or drug induced liver injury) innate and adaptive immune dysfunction may cause acute or chronic immune mediated liver injury. We recently found that liver has large amount of αβTCR+CD4-CD8- T cells (DN T cells) than spleen, and these liver DN T cells’ function is still unclear. Our preliminary data showed in concanavalin A (ConA) induced hepatitis, peripheral DN T cells were significantly increased and inhibited liver immune injury. In this study, we aim to determine the dynamic changes of the number and function of DN T cells in the liver and spleen during ConA induced liver autoimmune hepatitis. Further evaluate the origin and mechanism of DN T cells in liver immune mediated injury, and the migration of DN T cells between liver and spleen. This study will give support to our better understanding of the function and mechanism of DN T cells in liver immune system, and its feasibility in application as a promising cell-based strategy for treatment of liver immune mediated injury.

肝脏具有独特的结构、生理功能，含有独特的免疫细胞亚群，形成了独特的区域免疫特性，与肝脏疾病的发生、发展密切相关。然而肝脏中一些免疫细胞的来源、与脾脏等淋巴器官的关系以及在肝脏损伤中扮演的角色仍不清楚。我们的前期实验显示，肝脏存在大量功能不明确的αβTCR+CD4-CD8- T淋巴细胞（DN T细胞）。ConA诱导肝脏免疫损伤时，小鼠脾脏的DN T细胞成倍增加，抑制ConA诱导的肝脏免疫损伤，这在文献中未见报道。我们拟通过常用的自身免疫性肝病模型-ConA诱导的肝脏免疫损伤模型，对比肝脏、脾脏DN T细胞的数量及功能的变化；对脾脏增加的DN T 细胞的来源以及发挥保护作用的机制进行深入研究；同时对免疫性肝脏损伤中DN T 细胞的脾脏-肝脏趋化进行初步探讨。本研究将为自身免疫性肝病的机体保护机制增加新的内容，为探索新的基于DN T细胞的的免疫的干预策略提供理论基础。

CD4+ T淋巴细胞是适应性免疫系统的重要组成部分，可以分化为多种效应性和调节性T细胞。在本课题中，我们主要对ConA诱导的免疫性肝损伤中双阴性T细胞（DN T细胞）的变化功能进行了4方面的研究。ConA 诱导的免疫性肝脏损伤中，肝脏、脾脏和外周血中DN T 淋巴细胞的变化研究；DN T 细胞对ConA 诱导的免疫性肝脏损伤的保护机制研究；ConA 诱导的免疫性肝脏损伤中，增加的DN T 细胞的细胞来源的研究；ConA 诱导的免疫性肝脏损伤中，DNT 细胞体内趋化的初步研究。. 在本课题中，我们证明了CD4-CD8-NK1.1-双阴性T细胞在ConA所致自身免疫性肝炎的外周淋巴组织中，特别是在脾脏中显著增多。转移这些ConA诱导增加的DNT细胞至小鼠体内可通过抑制淋巴细胞的增殖及促进淋巴细胞凋亡而发挥保护作用。此外，我们进一步发现该保护作用主要是通过穿孔素实现。同时我们也发现ConA诱导的DNT细胞是由CD4+而非CD8+ T细胞转化而来，且该转化过程主要受OX40调控。 此外我们也发现DN T迁移到肝脏炎症部位主要通过CXCR3-CXCL9/CXCL10相互作用实现。. 总之，通过上述研究，我们阐述了CD4+ T细胞转化的DNT细胞参与并保持体内免疫系统平衡，这种分化途径在自身免疫性疾病的预防和治疗中具有潜在的应用。