ALCOHOL AND LIVER ENDOTHELIAL CELLS IN IMMUNE RESPONSES

酒精性肝病在美国是一个主要的健康问题。 慢性酒精摄入会产生一系列肝损伤， 从脂肪浸润到酒精性肝炎再到肝硬化的 乙醇产生有害影响的机制还没有 被明确定义。有证据表明直接毒性 乙醇及其代谢物以及免疫介导的毒性。 目前的大部分工作表明，非实质细胞的 肝脏在肝纤维化的发病机制中起一定作用。当库普弗 细胞和Ito细胞已经被相当广泛地研究， 了解LEC在酒精性肝病中的作用。这笔赠款 提出的工作将开始，以解决肝内皮细胞的作用， 细胞激活免疫系统和加剧酒精肝 疾病肝内皮细胞在宿主防御中起主要作用， 通过所谓的"清道夫"功能， 识别、内化和降解各种修饰的蛋白质， 细胞外基质成分。初步数据显示， 慢性乙醇给药改变受体介导的内吞作用 各种各样的大分子，从而减少了它们的重要性。 在肝网状内皮系统中起清除剂的作用。 此外，肝内皮细胞在清除 乙醛修饰的蛋白质和代谢这些蛋白质的能力， 异常物质可能随着长期存在而逐渐受损 乙醇暴露导致免疫反应的发展， 这些经过修饰的蛋白质。本研究的主要目的 项目是定义和描述乙醇的影响， 给药对受体介导的内吞作用（RME）过程的影响 肝内皮细胞（LEC），可能会导致发展中国家的 对修饰的自身蛋白的免疫反应。具体目标是：（1） 通过各种方法确定乙醇给药对RME的影响， 清除剂受体;甲醛处理的牛血清白蛋白（f- Alb），非酶糖基化牛血清白蛋白（AGE-Alb）， 乙酰化低密度脂蛋白（A-LDL），透明质酸（HA）， 氧化低密度脂蛋白（Ox-LDL）、卵清蛋白（OVA）和可溶性 由肝脏吸收和代谢的免疫复合物（FcR） 2）确定肝内皮细胞是否发挥 在清除乙醛修饰的蛋白质中的作用，如果是这样， 这种功能随着长期使用乙醇而改变。另夕h 诱导这种清除所需的乙醛修饰水平 3）确定是否存在特异性抗体 乙醛修饰的蛋白质加合物可以抑制结合和/或 生理相关乙醛修饰BSA的内吞作用 为了更好地表征用于结合的位点;以及4） 确定乙醇诱导的内吞作用减少是否导致 肝脏上乙醛修饰蛋白的长期存在 内皮细胞表面结合到其适当的 受体的修饰的自身蛋白在LEC上表达的能力 诱导体液和/或细胞免疫应答的膜将被 测定这些研究应有助于澄清 乙醇修饰的LEC功能和随后的免疫应答的作用 酒精性肝损伤的发病机制

Alcoholic liver disease is a major health problem in the UnIted States. Chronic ethanol ingestion produces a spectrum of liver injury ranging from fatty infiltration to alcoholic hepatitis to cirrhosis. The mechanisms by which ethanol produces its harmful effect have not yet been clearly defined. There is evidence implicating both direct toxicity of ethanol and its metabolites as well as an immune-mediated toxicity. Much of the current work suggests that non-parenchymal cells of the liver play a role in the pathogenesis of liver fibrosis. While Kupffer cells and Ito cells have been studied fairly extensively, little is known about the role of LEC in alcohol liver disease. This grant proposes work which will begin to address the role of liver endothelial cells in activating the immune system and exacerbating alcohol liver disease. Liver endothelial cells play a major role in host defense and homeostasis via their so-called 'scavenger' function whereby they recognize, internalize and degrade a variety of modified proteins and extracellular matrix components. Preliminary data demonstrates that chronic ethanol administration alters receptor mediated endocytosis of a variety of macromolecules, thereby diminishing their important function as scavengers in the hepatic reticuloendothelial system. Additionally, liver endothelial cells play a role in the clearance of acetaldehyde modified proteins and that the ability to metabolize these abnormal substances may become progressively impaired with longstanding ethanol exposure resulting in the development of an immune response to these modified proteins. The principal objective of the current research project is to define and characterize the effects of ethanol administration on the process of receptor mediated endocytosis (RME) in liver endothelial cells (LEC) that may result in the development of an immune response to modified self-proteins. The specific aims are: 1) To determine the effect of ethanol administration on RME by various scavenger receptors for; formaldehyde treated bovine serum albumin (f- Alb), nonenzymatically glycosylated bovine serum albumin (AGE-Alb), acetylated low density lipoproteins (A-LDL), hyaluronic acid (HA), oxidized low density lipoproteins (Ox-LDL), ovalbumin (OVA) and soluble immune complexes (FcR) which are taken up and metabolized by liver endothelial cells; 2) To determine whether liver endothelial cells play a role in clearance of acetaldehyde modified proteins, and if so whether this function is altered with long-term ethanol use. Additionally, the level of acetaldehyde modification necessary to induce this clearance will be investigated; 3) Determine whether antibodies to specific acetaldehyde modified protein adducts can inhibit the binding and/or endocytosis of the physiologically relevant acetaldehyde modified BSA in an effort to better characterize the site for binding; and, 4) Determine whether ethanol induced decreases in endocytosis results in an extended presence of acetaldehyde modified proteins on the liver endothelial cell surface following binding to their appropriate receptor. The ability of modified self-proteins expressed on LEC membranes to Induce humoral and/or cellular immune responses will be determined. These studies should contribute to the clarification of the role of ethanol modified LEC function and subsequent immune responses in the pathogenesis of alcohol liver injury.