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）的发展有关，酒精性肝病是美国包括退伍军人人群发病率和死亡率的主要原因。ALD的突出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理解仍然不完整。先前已经表明，肝细胞蛋白运输途径被发现对酒精的有害影响高度敏感。特别地，我们的实验室鉴定了受体介导的内吞作用（RME）过程中的多种乙醇诱导的改变，并且更具体地，我们发现乙醇处理导致肝细胞特异性脱唾液酸糖蛋白（ASGP）受体的功能显著受损。然而，将观察到的ASGP受体功能的改变转化为ALD的发生率和/或严重程度仍然没有得到表征。近年来研究表明，ASGP受体对免疫细胞的识别和随后的调节可能是其潜在的生理作用。在这个建议的初步研究中，我们已经证明，ASGP受体特异性结合淋巴细胞，肝受体的缺乏导致肝内T细胞的积累和增强的肝损伤。因此，我们提出ASGP受体在健康肝脏中的免疫细胞的调节中具有作用，并且乙醇诱导的ASGP受体功能的损伤可导致由T细胞介导的事件引起的肝损伤增加。这项研究的总体工作假设是，ASGP受体在肝细胞和活化的T淋巴细胞（已知在肝损伤后积累的免疫细胞）之间建立了联系，这有助于清除潜在的破坏性T细胞。此外，作为乙醇介导的ASGP受体改变的结果，T细胞的清除发生改变，导致异常淋巴细胞积聚，这些事件可能有助于肝炎的发展和ALD的进展。我们将解决这些假设与以下具体目标：在初步研究中，识别和结合的T淋巴细胞的肝细胞ASGP受体将在体外进行表征。接下来，将分析由于ASGP受体介导的肝细胞-淋巴细胞相互作用而触发的淋巴细胞清除机制（吞噬作用和/或T细胞死亡机制）。最后，提出了体内研究，以证明改变或缺乏功能性ASGP受体在免疫细胞相关肝损伤的发展中的重要性，使用乙醇给药沿着ASGP受体敲除小鼠用诱导剂T细胞介导的肝炎治疗的模型。从这项研究中获得的信息可以显着影响我们对肝细胞-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的损伤如何导致肝脏疾病的增强的理解。总之，这项工作的目的是建立和表征肝脏ASGP受体在免疫调节中的作用，以及这一过程的改变是否会影响免疫功能。

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