Kupffer细胞上GITRL在大鼠肝移植免疫耐受重建中的作用研究

Immune rejection is an important complication of liver transplantation. T effector cells (Teff) promote immune rejection by delayed hypersensitivity and cytotoxicity, in other hand T regulate cells (Treg) play an immune tolerance by suppressing Teff. Newly discovered that antigen-presenting cells activated Treg to break Treg-mediated immune tolerance by glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR), and inhibiting an interaction of GITR ligand (GITRL) and GITR induces immune tolerance of skin grafts.Our preliminary studies have shown that Kupffer cells (KC) promote immune rejection and is highly expressed GITRL, but the rejection mechanism of GITRL in liver transplant has not been elucidated. This topic is intended to KC as target cells, GITRL as the starting point, separating KC and establishing liver transplantation model, and using technical means of express GITRL and GITRL-siRNA plasmid to enhance or inhibit the expression of GITRL in KC, then explore Treg and Teff proliferation and function infulenced by the GITRL to clarify the role and molecular mechanism of GITRL in tolerance reconstruction of liver transplant.This will be an advantage for the tolerance reconstruction of liver transplantation.

免疫排斥是肝移植重要的并发症，T效应细胞（Teff）介导的迟发性超敏反应和细胞毒作用促进免疫排斥，T调节细胞(Treg)通过抑制Teff发挥免疫耐受。新近发现抗原递呈细胞，通过糖皮质激素诱导的肿瘤坏死因子受体相关蛋白（GITR），激活Treg后打破Treg介导的免疫耐受。抑制GITR配体（GITRL）与GITR的相互作用能诱导皮肤移植的免疫耐受。我们的前期研究证明Kupffer细胞（KC）促进排斥反应，并且高度表达GITRL，但GITRL在肝移植排斥中的作用机制尚未阐明。本课题拟以KC为靶细胞、GITRL为切入点，分离KC并建立肝移植模型，采用过表达GITRL、GITRL-siRNA质粒等技术手段，增强或抑制GITRL在KC的表达，探讨GITRL对Treg和Teff增殖、功能的影响，阐明GITRL在肝移植免疫耐受重建中的作用及分子机制。为肝移植免疫耐受的重建做些有益的探索工作。

免疫排斥是肝移植重要的并发症，T效应细胞（Teff）介导的迟发性超敏反应和细胞毒作用促进免疫排斥，T调节细胞(Treg)通过抑制Teff发挥免疫耐受。新近发现抗原递呈细胞，通过糖皮质激素诱导的肿瘤坏死因子受体相关蛋白（GITR），激活Treg后打破Treg介导的免疫耐受。抑制GITR配体（GITRL）与GITR的相互作用能诱导皮肤移植的免疫耐受。我们的前期研究证明Kupffer细胞（KC）促进排斥反应，并且高度表达GITRL，但GITRL在肝移植排斥中的作用机制尚未阐明。本课题通过细胞和动物模型证实GITRL在调节KCs免疫抑制功能及诱导肝移植免疫耐受中发挥重要作用，抑制KCs中GITRL表达，可通过抑制LPS/TLR4/ MAPK及IRF3等通路活性，减少Th1类促炎细胞因子的分泌、抑制KCs表面共刺激分子的表达，同时诱导KCs表型分子向M2型重塑。抑制GITRL还通过TRIF/IRF3/IFNβ调控Th细胞分化、增强Treg细胞功能，抑制Teff细胞激活、增殖，进而负向调控免疫应答过程。在肝移植急性排斥反应中，抑制GITRL还能减少移植肝脏内CD4T细胞局部浸润、促进其凋亡，最终改善了受体肝脏功能、延长了受体生存时间、减轻了排斥反应对肝脏组织的损伤。为免疫耐受的重建提供了充分的理论依据。