Alcohol Alters Hepatic Immune Function: Role of the Asialoglycoprotein Receptor

描述(由申请人提供)： 摘要长期饮酒与酒精性肝病(ALD)的发生有关，ALD是美国包括退伍军人在内的发病率和死亡率的主要原因。酒精性肝病的显著特征包括乙醇介导的细胞改变、脂肪变性和肝脏炎症；然而，对所涉及的机制的全面了解仍然不完整。此前已有研究表明，肝细胞蛋白转运途径对酒精的有害影响非常敏感。特别是，我们的实验室在受体介导的内吞作用(RME)过程中发现了多种乙醇诱导的变化，更具体地说，我们发现乙醇处理导致肝细胞特异性去唾液酸糖蛋白(ASGP)受体的功能显著受损。然而，将观察到的ASGP受体功能的变化与ALD的发生率和/或严重程度进行转换仍然没有特征性。最近有研究表明，免疫细胞的识别和随后的调节可能是ASGP受体的一个潜在的生理作用。在对这一提议的初步研究中，我们已经证明了ASGP受体与淋巴细胞特异性结合，并且肝脏受体的缺失会导致肝内T细胞的聚集和肝脏损伤的加重。因此，我们认为ASGP受体在健康肝脏的免疫细胞调节中起作用，乙醇诱导的ASGP受体功能损伤可导致T细胞介导的事件导致的肝损伤加重。这项研究的总体工作假设是，ASGP受体在肝细胞和激活的T淋巴细胞(已知在肝损伤后积聚的免疫细胞)之间建立联系，有助于有益地清除潜在的破坏性T细胞。此外，由于乙醇介导的ASGP受体改变，T细胞的清除发生改变，导致淋巴细胞异常聚集，这一事件可能有助于肝炎的发展和ALD的进展。在最初的研究中，T淋巴细胞与肝细胞ASGP受体的识别和结合将在体外表征。接下来，将分析ASGP受体介导的肝细胞-淋巴细胞相互作用所触发的淋巴细胞清除机制(吞噬和/或T细胞死亡机制)。最后，利用乙醇给药模型和ASGP受体基因敲除小鼠治疗T细胞介导性肝炎的模型，建议进行体内研究，以证明功能改变或缺失的ASGP受体在免疫细胞相关肝损伤发展中的重要性。从这项研究中获得的信息可以极大地影响我们对肝细胞-淋巴细胞相互作用如何维持肝脏中适当的T细胞稳态，以及这种相互作用中的损伤如何导致肝脏疾病的加强的理解。总之，这项工作旨在建立和表征肝脏asgp受体在免疫调节中的作用，以及这一过程的变化是否

DESCRIPTION (provided by applicant): ABSTRACT Chronic alcohol consumption is associated with the development of alcoholic liver disease (ALD), a major cause of morbidity and mortality in the U.S. including our Veteran population. Prominent features of ALD include ethanol-mediated cellular alterations, steatosis and hepatic inflammation; however, a comprehensive understanding of the mechanisms involved remains incomplete. It has previously been shown that hepatocellular protein trafficking pathways were found to be highly susceptible to the detrimental effects of alcohol. In particular, our laboratory identified multiple ethanol-induced alterations in the process of receptor- mediated endocytosis (RME) and more specifically, we discovered that ethanol treatment resulted in marked impairments in the function of the hepatocyte-specific asialoglycoprotein (ASGP) receptor. However, translating the observed alterations in ASGP receptor function to the incidence and/or severity of ALD remains uncharacterized. Recently it has been suggested that the recognition and subsequent regulation of immune cells could be a potential physiological role of the ASGP receptor. In preliminary studies for this proposal, we have demonstrated that the ASGP receptor specifically binds to lymphocytes and that the absence of the hepatic receptor results in the accumulation of intrahepatic T cells and enhanced liver injury. Therefore, we propose that the ASGP receptor has a role in the regulation of immune cells in the healthy liver and that ethanol-induced impairments in ASGP receptor function can result in increased liver injury caused by T cell- mediated events. The overall working hypothesis of this study is that ASGP receptors establish connections between hepatocytes and activated T lymphocytes (immune cells that are known to accumulate following liver injury) which facilitate the beneficial removal of potentially damaging T cells. Furthermore, as a consequence of ethanol-mediated alterations to the ASGP receptor, altered clearance of T cells occurs leading to abnormal lymphocyte accumulation, events that could contribute the development of hepatitis and the progression of ALD. We will address these hypotheses with the following specific aims: In initial studies, the recognition and binding of T lymphocytes to the hepatocyte ASGP receptor will be characterized in vitro. Next, lymphocyte clearance mechanisms (phagocytosis and/or T cell death mechanisms) triggered as a result of ASGP receptor- mediated hepatocyte-lymphocyte interactions will be analyzed. And finally, in vivo studies are proposed to demonstrate the importance of altered or absent functional ASGP receptors in the development of immune cell related liver injury using models of ethanol administration along with an ASGP receptor knockout mouse treated with inducers T cell-mediated hepatitis. Information gained from this research can significantly impact our understanding of how hepatocyte-lymphocyte interactions maintain proper T cell homeostasis in the liver and how impairments in such interactions can lead to enhancements in liver disease. Overall, this work aims to establish and characterize the role of the hepatic ASGP receptor in immune regulation and whether the alterations of this proce