Extracellular Matrix Regulates Hepatic Stellate Cell Activation and Fibrosis

项目摘要 肝纤维化是慢性肝病如B型和C型肝炎感染的结果， 酒精性和非酒精性脂肪性肝炎（NASH）。目前尚无有效的抗肝纤维化药物 肝硬化因此，肝纤维化/肝硬化的未满足的医疗需求是显著的。 肝脏炎症是肝星状细胞（hepatic stellate cell，HSCs）活化和肝纤维化的重要机制。 活化的HSC产生细胞外基质（ECM），包括胶原蛋白、纤连蛋白和透明质酸（HA）。 内源性HA与肺、肾、关节、心脏和脑的疾病进展有关。在 肝硬化患者血液中HA水平升高。然而， 肝纤维化中产生的内源性HA尚未确定。HA是以高分子 由透明质酸合酶（HAS）1-3形成的重量形式（HMW; MW> 1000 kDa）。在炎症情况下，HA是 降解为低分子量（LMW）形式（MW约100- 300 kDa）。LMW-HA加剧组织损伤， 炎症通过结合其受体CD 44和TLR 4。 本研究的目的是确定内源性HA的生物学功能及其在肿瘤发生发展中的作用。 HSC激活和肝纤维化中的下游效应途径。根据以前的出版物和 在我们的初步研究中，我们假设HAS 2介导的HSC衍生的HA和HA的下游 效应子途径促进HSC活化和肝纤维化。此外，我们进一步假设， 以HA为靶点，可以开发一种治疗肝纤维化的新的干预策略。 为了验证我们的假设，我们将研究HSC中HAS 2介导的HA产生是否促进肝脏 使用HSC特异性Has 2敲除（Has 2 β HSC）小鼠通过功能丧失和获得方法治疗纤维化， HAS 2转基因（ASMA-HAS 2 Tg）小鼠。我们还将使用人体组织样本来检查HSC， 人肝病中HAS 2和HA的来源（目的1）。我们将研究转录和 HSC中HAS 2表达的转录后调控是调控失调的分子机制 HAS 2在肝纤维化中的表达（目的2）。然后，我们将研究Notch 1信号传导作为HA的作用。 HSC活化和肝纤维化的下游效应子途径（Aim 3）。最后，我们将研究 阻断HA合成治疗肝纤维化的干预潜力（目的4）。

Project Summary Liver fibrosis is the consequence of chronic liver diseases, such as hepatitis B and C infection, and alcoholic and non-alcoholic steatohepatitis (NASH). Currently there is no effective anti-fibrotic agent for liver cirrhosis. Therefore, the unmet medical needs for liver fibrosis/cirrhosis are significant. Liver inflammation is a crucial mechanism for activation of hepatic stellate cell (HSCs) and liver fibrosis. Activated HSCs produce extracellular matrix (ECM) including collagen, fibronectin, and hyaluronic acids (HA). Endogenous HA have been implicated in the disease progression of lungs, kidneys, joints, heart, and brain. In the liver, patients with liver cirrhosis show elevated HA levels in the blood. However, the biological functions of endogenous HA produced in liver fibrosis have not been determined. HA are produced in high molecular weight forms (HMW; MW>1000kDa) by hyaluronan synthase (HAS) 1-3. In the setting of inflammation, HA are degraded into low molecular weight (LMW) forms (MW~100-300kDa). LMW-HA exacerbates tissue injury and inflammation through binding to its receptors, CD44 and TLR4. The objective of this study is to determine the biological functions of endogenous HA and its downstream effector pathway in HSC activation and in liver fibrosis. Based on previous publications and our preliminary studies, we hypothesize that HAS2-mediated HSC-derived HA and HA's downstream effector pathways promote HSC activation and liver fibrosis. Moreover, we further hypothesize that by targeting HA a new interventional strategy for treating liver fibrosis can be developed. To test our hypotheses, we will investigate if HAS2-mediated HA production in HSCs promotes liver fibrosis through loss- and gain-of-function approaches using HSC-specific Has2 knockout (Has2∆HSC) mice and HAS2 transgenic (ASMA-HAS2 Tg) mice. We will also use human tissue samples to examine HSCs as the source of HAS2 and HA in human cirrhotic livers (Aim 1). We will investigate the transcriptional and posttranscriptional regulation of HAS2 expression in HSCs as the molecular mechanisms of dysregulated HAS2 expression in liver fibrosis (Aim 2). We will then investigate the role of Notch1 signaling as the HA's downstream effector pathway for HSC activation and liver fibrosis (Aim 3). Finally, we will examine interventional potential of blocking HA synthesis for treating liver fibrosis (Aim 4).