Liver Dendritic Cells in Tolerance and Immunity

描述(由申请人提供)：肝脏缺血再灌注(I/R)在肝部分切除、肝移植和低血容量性休克后引起不良的高炎症反应。目前，还没有有效的治疗方法。虽然树突状细胞(DC)现在被认为是全身免疫和炎症的主要介质，但我们对肝脏DC的了解还很初级。在我们资助的头5年中，我们初步建立了新鲜分离的小鼠和人肝脏树突状细胞的T细胞刺激能力。在这次竞争性续签申请中，我们将研究肝脏树突状细胞在肝脏炎症中的先天作用。Toll样受体是存在于免疫细胞上的进化保守蛋白质，识别病原体、免疫危险信号和内源性核酸，进而激活天然免疫。我们发现TLR9是检测低甲基化细菌CpG基序和内源性DNA的细胞内受体，调节肝脏I/R中常规DC的抗炎反应。此外，我们还发现浆细胞样DC在肝脏I/R损伤中发挥保护作用。因此，我们假设内源性配体在肝脏I/R损伤的免疫发病机制中调节DC。在目标1中，我们将确定内源性配体对传统DC对肝脏I/R的调节作用。在目标2中，我们将建立血浆细胞样树突状细胞在肝脏I/R中的保护机制。在目标3中，我们将在体外人肝I/R模型中建立损伤的TLR要求。我们的研究与人类疾病有直接关系，并可能导致使用TLR阻滞剂治疗涉及肝脏和其他器官，如心、肾、肺和脑的人I/R。

DESCRIPTION (provided by applicant): Liver ischemia reperfusion (I/R) induces an untoward hyperinflammatory response following partial hepatectomy, liver transplantation, and hypovolemic shock. Currently, there are no effective therapies. While dendritic cells (DCs) are now recognized as the principal mediators of immunity and inflammation throughout the body, our understanding of liver DCs has been rudimentary. During our first 5 years of funding, we primarily established the T cell stimulating capacity of freshly isolated mouse and human liver DCs. In this competitive renewal application for an additional 5 years of funding, we will investigate the innate role of hepatic DCs in liver inflammation. Toll-like receptors (TLRs) are evolutionarily conserved proteins present on immune cells that recognize pathogens, immunologic danger signals and endogenous nucleic acids and subsequently activate innate immunity. We have discovered that TLR9, the intracellular receptor that detects hypomethylated bacterial CpG motifs and endogenous DNA, modulates anti-inflammatory responses by conventional DCs in liver I/R. Additionally, we have discovered that plasmacytoid DCs exert protective effects in I/R. Thus, we hypothesize that endogenous ligands regulate DCs in the immunopathogenesis of liver I/R injury. In Aim 1, we will determine the regulation of liver I/R by conventional DCs in response to endogenous ligands. In Aim 2, we will establish the mechanism of protection by plasmacytoid DCs in liver I/R. In Aim 3, we will establish the TLR requirements for injury in an in vitro model of human liver I/R. The proposed experiments will increase our knowledge regarding the mechanisms of hepatic inflammation. Our investigation has direct relevance to human disease and may lead to the use of TLR blockade for the treatment of hu- man I/R that involves the liver and other organs, such as the heart, kidney, lung, and brain.