TIM-3 Negative Costimulation Signaling at the Innate-Adaptive Immune interface in Liver Transplant Ischemia-Reperfusion Injury

 描述（由申请人提供）：缺血再灌注损伤（IRI）仍然是限制终末期肝病和肝源性肿瘤患者原位肝移植（奥尔特）成功的主要障碍。我们的小组开创了肝脏IRI的概念，这是一种外源性Ag非依赖性，先天免疫主导的无菌炎症反应，需要活化的CD 4 + T细胞来促进组织损伤。T细胞免疫球蛋白粘蛋白（TIM）-3受体已被认为是许多自身/同种异体免疫病理和器官移植中T细胞活化的中心调节剂。我们报道了TIM-3 - Gal-9通路的破坏加剧了小鼠肝脏受到热IR的肝细胞损伤。然后，我们发现受体CD 4 +TIM-3+细胞赋予对肝脏IRI的抵抗，这表明在移植受体中应用T细胞靶向治疗时，应保留离散的宿主T细胞亚群。本研究旨在探讨TIM-3信号通路在临床相关的小鼠模型中肝脏IRI机制中的作用。首先，我们发现应激肝细胞表达Gal-9和HMGB 1，即，已知的TIM-3配体。其次，我们发现TIM-3在活化的肝内皮细胞（LEC）上的稳健表达。这些初步的数据使我们提出了一个中心假设，即在宿主循环CD 4 + T细胞/移植LEC上表达的肝细胞源性Gal-9/HMGB 1和TIM-3之间的负调节对于控制组织损伤是必不可少的，并且在IR应激的奥尔特中施加细胞保护表型。两个相互关联的具体目标将测试这一假设：目标1：定义肝细胞Gal-9 -CD 4 + T细胞TIM-3负调控赋予奥尔特抵抗IR应激的分子机制。目标1.1。假设：Gal-9 - TIM-3信号传导触发抗氧化反应，其中扩增的Nrf 2活性抑制巨噬细胞NF κ B B/炎症反应。目标1.2。假设：Gal-9 - TIM-3信号通过Keap 1/Nrf 2氧化还原网络增强肝细胞自噬。 目的2：明确肝细胞HMGB 1-内皮细胞TIM-3负调控加重奥尔特IRI的分子机制。目标2.1。假设：IR损伤前的HMGB 1调节触发肝内皮TIM-3的激活以抑制奥尔特中巨噬细胞的运输和隔离。目标2.2。假设：肝细胞HMGB 1-内皮TIM-3信号转导促进LEC保护表型。 这些研究将识别先天适应性免疫界面的新机制，该机制控制IR应激奥尔特中的器官损伤/促进体内平衡;并应有助于开发新疗法以增加供体器官库并改善临床结局。

 DESCRIPTION (provided by applicant): Ischemia-reperfusion injury (IRI) remains the primary obstacle limiting the success of orthotopic liver transplantation (OLT) in patients with end-stage liver disease and those with tumors of hepatic origin. Our group has pioneered the concept that hepatic IRI, an exogenous Ag-independent, innate immune-dominated sterile inflammation response, requires activated CD4+ T cells to facilitate tissue damage. T cell Immunoglobulin Mucin (TIM)-3 receptor has been recognized as a central regulator of T cell activation in a number of auto- / allo-immunity pathologies and organ transplantation. We reported that disruption of TIM-3 - Gal-9 pathway exacerbated hepatocellular injury in mouse livers subjected to warm IR. Then, we found that recipient CD4+TIM-3+ cells conferred resistance against liver IRI, suggesting a discrete host T cell subset should be spared while applying T cell-targeted therapy in transplant recipients. This proposal explores the function of TIM-3 signaling pathway in the mechanism of hepatic IRI in a clinically relevant mouse model of extended cold storage followed by orthotopic liver transplantation (OLT). First, we found that stressed hepatocytes express Gal-9 and HMGB1, i.e., known TIM-3 ligands. Second, we discovered robust expression of TIM-3 on activated liver endothelial cells (LEC). These preliminary data have led us to a central hypothesis that negative regulation between hepatocellular-derived Gal-9/HMGB1 and TIM-3 expressed on host circulating CD4+ T cells/graft LEC is essential to control tissue injury, and impose cytoprotective phenotype in IR-stressed OLT. Two interlocked specific aims will test this hypothesis: Aim 1: Define molecular mechanisms by which hepatocyte Gal-9 - CD4+ T cell TIM-3 negative regulation confers OLT resistance against IR stress. Aim 1.1. Hypothesis: Gal-9 - TIM-3 signaling triggers anti-oxidant response in which amplified Nrf2 activity represses macrophage NFB/inflammation responses. Aim 1.2. Hypothesis: Gal-9 - TIM-3 signaling enhances hepatocyte autophagy via Keap1/Nrf2 redox network. Aim 2: Define molecular mechanisms by which hepatocellular HMGB1 - endothelial TIM-3 negative regulation alleviates IRI in OLT. Aim 2.1. Hypothesis: HMGB1 conditioning prior to IR insult triggers activation of liver endothelial TIM-3 to repress macrophage trafficking and sequestration in OLT. Aim 2.2. Hypothesis: Hepatocellular HMGB1 - endothelial TIM-3 signaling promotes LEC protective phenotype. These studies will discern novel mechanisms at the innate-adaptive immune interface, which control organ damage/promote homeostasis in IR-stressed OLT; and should contribute to the development of new therapies to increase donor organ pool and improve clinical outcomes.