Extracellular Matrix Regulates Hepatic Stellate Cell Activation and Fibrosis

项目摘要 肝纤维化是慢性肝病的后果，如乙型和丙型肝炎感染，以及 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。 肝硬变。因此，未得到满足的肝纤维化/肝硬变的医疗需求是重要的。 肝脏炎症是肝星状细胞(HSCs)活化和肝纤维化的重要机制。 活化的肝星状细胞产生细胞外基质(ECM)，包括胶原、纤维连接蛋白和透明质酸(HA)。 内源性HA与肺、肾、关节、心脏和脑的疾病进展有关。在……里面 在肝脏，肝硬变患者血液中的HA水平升高。然而，它的生物学功能 肝纤维化时产生的内源性HA尚未确定。羟基磷灰石是以高分子形式产生的 体重(HMW；MW&GT；1000 kDa)由透明质酸合成酶(HAS)1-3组成。在炎症环境中，HA是 降解成低分子量(Mw~100-300 kDa)形式。LMW-HA加剧组织损伤和 炎症通过与其受体CD44和TLR4结合。 本研究的目的是确定内源性HA及其受体的生物学功能。 HSC活化和肝纤维化中的下游效应通路。基于以前的出版物和 我们的初步研究，我们假设HAS2介导的HSC来源的HA及其下游 效应通路促进HSC活化和肝纤维化。此外，我们进一步假设，通过 以HA为靶点，可以开发一种新的治疗肝纤维化的介入策略。 为了验证我们的假设，我们将研究HAS2介导的HSCs中HA的产生是否促进肝脏 肝星状细胞特异性Has2基因敲除(Has2∆)小鼠和 HAS2转基因(ASMA-HAS2TG)小鼠。我们还将使用人类组织样本来检测HSCs作为 人类肝硬变中HAS2和HA的来源(目标1)。我们将调查转录和 HAS2基因转录后调控是HSCs表达异常的分子机制 HAS2在肝纤维化中的表达(目标2)。然后我们将研究Notch1信号作为HA的作用 肝星状细胞激活和肝纤维化的下游效应通路(目标3)。最后，我们将检查 阻断HA合成治疗肝纤维化的干预潜力(目标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).