Innate Immune Response and Intestinal Inflammation

描述(由申请人提供)： 肝纤维化，即细胞外基质蛋白的积聚，发生在大多数类型的慢性肝病中。肝纤维化患者可能进展为肝硬变，继而出现门脉高压、肝功能衰竭和肝细胞癌。不幸的是，目前还没有有效的抗肝纤维化治疗方法来治疗慢性肝病。肝星状细胞(HSCs)活化是肝纤维化形成的中心事件。活化的HSCs是肝纤维化中产生细胞外基质蛋白的主要细胞类型，已确定的关键纤维化信号包括通过Toll样受体4(TLR4)传递的信号。TLR4信号转导所需的所有分子都是在HSCs激活过程中被诱导的，通过激活NFicB和JNK等信号通路，使活化的HSCs对脂多糖等TLR4配体产生反应，并合成促炎分子。TLR4突变小鼠对实验性肝纤维化具有抵抗力。该项目的目标是进一步明确TLR4导致肝纤维化的机制，并通过配体结合的可溶性受体测试TLR4作为潜在的治疗靶点。作为这一提议基础的基本假设如下：1.细胞内TLR4接头蛋白和效应器分子在内毒素刺激后对促炎基因表达的贡献不同。2.其他内源性配体包括高迁移率族蛋白1(HMGB1)直接与TLR4相互作用并诱导HSCs的促炎作用。3.使用调节TLR4信号的可溶性TLR4受体可以阻断促炎和致纤维化的作用。因此，我们希望实现四个具体目标。我们希望进一步定义TLR4在HSCs中介导其作用的信号通路和机制(目标1)。我们将研究HMGB1作为内源性TLR4配体对培养的HSCs以及在小鼠肝纤维化模型中的作用(目标2)。我们还想确定其他内源性TLR4配体是否介导了肝纤维化(目标3)。根据我们的初步数据，我们开发了一种可溶性TLR4受体，它可以抑制内毒素诱导的HSCs的信号转导和促炎作用。因此，我们希望扩大这些研究，并使用可溶性TLR4受体作为预防和治疗肝纤维化动物模型的方法(目标4)。总体目标是对HSCs的病理生理学有新的认识，并更好地了解慢性肝病的分子机制。最终，这种方法可能会为慢性肝病患者带来一种新的治疗方法。为了实现拟议的研究目标，我将获得更多尖端分子生物学技术方面的专业知识。在获奖期间，我将继续研究肝纤维化的基础研究，重点是“转化医学”--将最新研究转化为临床治疗。

DESCRIPTION (provided by applicant): Liver fibrosis, the accumulation of extracellular matrix proteins, occurs in most types of chronic liver disease. Patients with liver fibrosis may progress to cirrhosis with subsequent portal hypertension, hepatic failure and hepatocellular carcinoma. Unfortunately, there are no effective antifibrotic treatments for patients with chronic liver disease. Activation of hepatic stellate cells (HSCs) is the central event in liver fibrogenesis. Activated HSCs are the main extracellular matrix protein producing cell type in fibrotic liver and key fibrogenic signals have been identified including signaling through toll-like receptor 4 (TLR4). All molecules required for TLR4 signaling are induced during the activation process of HSCs, rendering activated HSCs responsive to TLR4 ligands such as lipopolysaccharide (LPS) with activation of signaling pathways including NFicB and JNK, and the synthesis of pro-inflammatory molecules. TLR4 mutant mice are resistant to experimental liver fibrosis. The goal of this project is to further define the mechanisms by which TLR4 leads to liver fibrosis and to test TLR4 as a potential target of therapy via ligand-binding soluble receptors. The underlying hypotheses that serve as the basis for this proposal are the following: 1. Intracellular TLR4 adaptor proteins and effector molecules contribute differently to pro-inflammatory gene expression following LPS stimulation. 2. Other endogenous ligands including high-mobility group box 1 (HMGB1) directly interact with TLR4 and induce pro-inflammatory effects in HSCs. 3. Pro-inflammatory and fibrogenic actions can be blocked by using a soluble TLR4 receptor that modulates TLR4 signaling. We therefore wish to pursue four specific aims. We want to further define the signaling pathways and mechanisms by which TLR4 mediates its effects in HSCs (aim 1). We will investigate the effect of HMGB1 as endogenous TLR4 ligand on cultured HSCs, and in a mouse model of liver fibrosis (aim 2). We also want to determine whether other endogenous TLR4 ligands mediate hepatic fibrogenesis (aim 3). As shown in our preliminary data, we developed a soluble TLR4 receptor, which inhibits LPS induced signaling and pro-inflammatory actions in HSCs. We therefore want to extend these studies and use the soluble TLR4 receptor as preventive and therapeutic approach in animal models of liver fibrosis (aim 4). The overall goal is to gain new insights into the pathophysiology of HSCs and to provide a better understanding of the molecular mechanisms underlying chronic liver diseases. Eventually this approach might lead to a novel therapy for patients with chronic liver disease. To achieve the proposed research aims, I will gain additional expertise in sophisticated molecular biology techniques. During the time of the award I will continue basic research to study liver fibrosis with an emphasis on "translational medicine" - taking the latest research and translating it into clinical therapies.