Nutritional Transcriptomics Approach for the Role of Astaxanthin in Liver Fibrosis

 描述(申请人提供)：肝纤维化是一种疤痕形成的过程，发生在大多数慢性肝病中。虽然肝纤维化可以进展为肝硬变，但它也是可逆的。肝星状细胞(HSC)在肝纤维化的发生、发展和消退中起着至关重要的作用。在肝损伤过程中，静止的HSC(QHSC)转化为肌成纤维细胞样活化的HSC(AHSC)，产生细胞外基质蛋白和纤维化细胞因子。在肝纤维化消退过程中，AHSC被细胞凋亡清除或失活至静止阶段。在肝纤维化消退过程中，有一半的AHSC被证明是失活的。因此，调节HSC的激活/失活是防治肝纤维化的重要靶点。到目前为止，还没有抗纤维化药物进入临床。对参与肝纤维化发展或消退的关键分子分子的有限了解一直是开发有效的抗肝纤维化治疗的主要挑战。我们之前使用各种实验模型系统的研究已经证明了新的发现：组蛋白脱乙酰酶9(HDAC9)在调节HSC激活中起关键作用；虾青素(ASTX)，一种叶黄素类胡萝卜素，抑制HDAC9的纤维化作用。重要的是，ASTX对HDAC9的抑制作用不仅阻止了HSC的激活，而且使AHSC恢复到静止状态，提示ASTX可能具有预防和消退肝纤维化的作用。为了扩大我们的新观察，识别HDAC9和ASTX调控下的与肝纤维化相关的基因特征是至关重要的。该项目的目标是进行全基因组转录组分析，以确定新的HDAC9调控的基因，ASTX的抗纤维化作用是通过这些基因来介导的，并证实在体内以及在各种慢性肝病的人类肝脏标本中的发现。根据我们强有力的初步观察，我们建立了一个中心假设，即HDAC9是一种参与qHSC激活的促纤维化介质。通过抑制HDAC9，ASTX发挥抗纤维化作用，防止HSC激活，促进AHSC在肝脏中的失活。ASTX对HDAC9的抑制作用，反过来又会阻止肝纤维化的发展，逆转纤维化状况，最终阻止纤维化进展为肝硬变。这一假说得到了我们强有力的初步结果的支持，我们将通过追求以下三个特定目标来检验这一假说：1)进行全基因组转录组学分析，以确定HDAC9和ASTX在野生型(WT)和Hdac9基因敲除小鼠的HSC中调节的纤维化分子介质；2)通过两种肝纤维化模型，即WT和Hdac9基因敲除小鼠的体内肝纤维化模型，确定HDAC9和ASTX在体内预防和消退肝纤维化的作用；以及3)验证HDAC9和ASTX调控的HSC体内和人肝纤维化组织中的候选纤维化基因。这项研究完成后，预计将对公众健康产生重大影响，因为将确定新的基因靶点，以建立有效和安全的策略，预防和治疗表现为纤维化的人类慢性肝病。

 DESCRIPTION (provided by applicant): Liver fibrosis is a scarring process that occurs in most of chronic liver diseases. While liver fibrosis can progress to cirrhosis, it is also reversible. Hepatic stellate cells (HSC) play a crucial role in the development and regression of liver fibrosis. During liver injury, quiescent HSC (qHSC) transdifferentiate to myofibroblasts-like activated HSC (aHSC) that produce extracellular matrix proteins and fibrogenic cytokines. During the regression of liver fibrosis, aHSC are removed by apoptosis or inactivated to a quiescent stage. A half of aHSC have been shown to be inactivated during the regression of liver fibrosis. Therefore, regulation of HSC activation/inactivation is a critical target for the prevention/therapy of liver fibrosis. No anti-fibrotic drugs have yet reached the clinic to date. Or limited knowledge of molecular players critically involved in the development or regression of liver fibrosis has been a primary challenge to the development of an effective anti-fibrotic therapy. Our previous studies using various experimental model systems have demonstrated novel findings that histone deacetylase 9 (HDAC9) play a critical role in the regulation of HSC activation; and astaxanthin (ASTX), a xanthophyll carotenoid, inhibits the fibrogenic action of HDAC9. Importantly, the inhibitory effect of ASTX on HDAC9 does not only prevent HSC activation, but reverts aHSC to a quiescent state, suggesting that ASTX may be able to prevent and regress liver fibrosis. To expand our novel observations, identifying gene signatures associated with liver fibrosis that are under the regulation of HDAC9 and ASTX is critical. The OBJECTIVES of this project are to conduct a genome- wide transcriptome analysis to identify new HDAC9-regulated genes by which the anti-fibrogenic effect of ASTX is mediated, and to corroborate the findings in vivo as well as in human liver specimens of various chronic liver diseases. As guided by our strong preliminary observations, we establish CENTRAL HYPOTHESIS that HDAC9 is a pro-fibrotic mediator involved in the activation of qHSC. By repressing HDAC9, ASTX exerts an anti-fibrotic action, preventing HSC activation and facilitating the inactivation of aHSC in the liver. The inhibitory effect of ASTX on HDAC9, in turn will prevent the development of liver fibrosis and regress the fibrotic condition, ultimately preventing the progression of fibrosis to cirrhosis. This hypothesis is supported by our strong preliminary results and we will test the hypothesis by pursuing the following three SPECIFIC AIMS: 1) To perform genome-wide transcriptome analysis to identify fibrogenic molecular mediators regulated by HDAC9 and ASTX in HSC from wild-type (WT) and Hdac9 knockout mice; 2) to determine the effect of HDAC9 and ASTX on the prevention and regression of liver fibrosis in vivo using two fibrosis mouse models, i.e., WT and Hdac9 knockout mice with CCl4-induced or diet-induced liver fibrosis; and 3) to validate candidate fibrotic genes in HSC regulated by HDAC9 and ASTX in vivo and in human fibrotic livers. Large IMPACT on public health is anticipated upon completion of this study as the new gene targets will be identified to establish effective and safe strategies for the prevention and therapy for human chronic liver diseases manifesting fibrosis.