TIM-1/TIM4信号通路在肝移植缺血再灌注损伤中的作用和机制研究

Hepatic injury due to prolonged ex-vivo cold storage followed by reperfusion remains a major cause of morbidity and mortality after orthotopic liver transplantation (OLT). T cell Immunoglobulin Mucin (TIM) family members, expressed on certain T cells and APCs, have attracted major attention as mediators of T cell activation and tolerance. TIM-1, originally described as a hepatitis A virus receptor (HAVCR1), was then identified as a kidney injury molecule (KIM-1). While absent on na?ve CD4 T cells, TIM-1 expression increases following TCR stimulation to provide positive co-stimulatory signal in T cell proliferation and Th1/Th17 cytokine production. This study analyzes mechanisms by which TIM-1 affects liver ischemia-reperfusion injury (IRI) in a clinically relevant murine model of prolonged cold storage followed by OLT. Livers from C57BL/6 mice, preserved at 4 C in UW solution for 20h, were transplanted to syngeneic recipients. There was an early (1h) increased accumulation of TIM-1+ activated CD4 T cells in the ischemic OLTs. Disruption of TIM-1 signaling with a blocking mAb ameliorated liver damage at 6h, evidenced by reduced sALT levels and well-preserved OLT architecture. Although adoptive transfer of CD4 T cells triggered fulminant liver damage in otherwise IR-resistant Rag-1 KO mice, adjunctive TIM-1 blockade reduced Tbet transcription, and abolished macrophage activation, ultimately restoring homeostasis in IR-stressed livers. TIM-4 is a natural ligand for TIM-1, In agreement with the effect of anti-TIM-1 mAb, we observed that the TIM-4/TIM-1 interaction delivers a positive signal and costimulates T cell proliferation. In the next step, we will use different liver donors with high TIM-1 or low TIM-1 to some kinds of mice(WT/Rag-1 KO/CD11c KO) while doing the secectivly TIM-4 blocking. Thus, TIM-1/TIM-4 signal is required in the mechanism of innate and adoptive immune-mediated hepatic IRI in OLT recipients.

肝脏缺血再灌注损伤是影响肝移植成功率和肝移植术后移植物功能的重要因素，其作用机制一直是国内外移植界关注的焦点。文献报道T细胞免疫球蛋白粘蛋白-1（TIM-1）表达在CD4+T细胞上，随着CD4+T细胞的激活，在辅助性T细胞-2（Th2）起主要作用的免疫反应中，TIM-1表达并起到重要作用。我们的研究证明基于小鼠原位肝移植（冷缺血）模型，围绕TIM-1/TIM-4信号通路对移植术后免疫调控机制的影响进行研究，目前已证明阻断TIM-1的表达能够有效改善小鼠肝移植术后肝脏缺血再灌注损伤。实验组拟通过选取带特殊标记T细胞小鼠的供肝移植到WT/Rag-1 KO/CD11c KO小鼠体内,同时进行TIM-4信号阻断，研究不同组间移植肝损伤程度。同时在体外培育T细胞，原代巨噬细胞及肝脏细胞，研究细胞免疫细胞、天然免疫细胞对效应细胞的作用。从体内及体外两方面探讨TIM-1/TIM-4信号通路影响移植肝功。