Kupffer细胞（KCs）在肝移植免疫中起着即促进排斥反应又诱导免疫耐受的双重角色，其原因与调控Th1/Th2平衡相关。项目组前期发现：通过增强Tim-3/Galectin-9途径抑制Th1型反应的免疫耐受诱导方案，效果并不理想。新近发现Tim-4参与了机体诸多免疫调控环节，增强该分子可促进Th2型反应、有效清除凋亡细胞和削弱APCs功能，其免疫调节机制与Tim-3不同，抑制效应可能比Tim-3更强，但尚未涉及移植领域。我们认为该分子在肝移植免疫中也起重要作用。因此，本项目选择肝KCs为靶细胞，以Tim-4为切入点，分离KCs并建立肝移植模型，采用过表达Tim-4、Tim-4-shRNAs质粒及Tim-4单克隆抗体，增强、抑制或功能阻断Tim-4在体内外表达，探讨Tim-4对KCs功能及其介导的凋亡细胞吞噬和Th2型反应的影响及相关分子机制，阐明该分子在诱导移植肝脏免疫耐受形成中的作用。

Kupffer cells (KCs), the most important resident macrophages of the liver, comprise one of the major population of the hepatic non nonparenchymal cell fraction, and the tolerogenic properties of the liver are generally accepted. Therefore increased attention has focused on the possible role and mechanism of KCs from liver allograft in tolerance induction. Over a decade of research, our group demonstrated that KCs played a dual role in the pathological changes after liver transplantation, and the mechanism is closely associated with modulating Th1/Th2 balance and its immune function. Our recent study found the method to induce immune tolerance via suppression Th1 immune response through Tim-3/Galectin-9 pathway was not effective in rat's liver transplantation. However, a few studies reported that Tim-4 plays a pivotal role in the regulation of immune function, including the APCs immune function, apoptotic cells clearance and Th1/Th2 balance. But so far there is no related research in solid organ transplantation, especially in liver. We hereby put forward a hypothesis that up-regulation of Tim-4 in KCs may induce liver transplant tolerance via cytokine-driven immune deviation, antigen-specific of apoptotic T cells clearance and active suppression. To clarify the role of the molecule in liver tolerance induction, we will separate KCs and establish liver transplantation model in mice, using AdV-Tim-4 or Tim-4-shRNAs plasmids or anti-Tim-4 mAb to enhance or inhibit Tim-4 expression both in vitro and in vivo. Once the hypothesis of up-regulation of Tim-4 in KCs mediating the self-tolerance induction in liver transplantation is corroborated, this molecule can become a novel target for treatment of acute rejection.