ALCOHOL AND LIVER ENDOTHELIAL CELLS IN IMMUNE RESPONSES

酒精性肝病是美国的一个主要健康问题。 长期摄入酒精会导致一系列肝损伤 从脂肪渗透到酒精性肝炎再到肝硬变。这个 乙醇产生有害影响的机制尚未得到证实。 都有明确的定义。有证据表明这两种直接毒性 乙醇及其代谢物的毒性以及免疫介导的毒性。 目前的许多工作表明，大脑中的非实质细胞 肝脏在肝纤维化的发病机制中起着重要作用。而库普弗 细胞和伊藤细胞已经得到了相当广泛的研究，但很少有 了解LEC在酒精性肝病中的作用。这笔赠款 提出将开始解决肝内皮细胞的作用的工作 细胞在激活免疫系统和加重酒精性肝脏中的作用 疾病。肝内皮细胞在宿主防御中发挥重要作用 通过它们所谓的“清道夫”功能实现的动态平衡 识别、内化和降解各种修饰的蛋白质和 细胞外基质成分。初步数据显示， 慢性乙醇摄入改变受体介导的内吞作用 各种大分子，从而削弱了它们重要的 在肝脏网状内皮系统中起清道夫的作用。 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 随着时间的延长，异常物质可能会逐渐受损 酒精暴露导致免疫反应的发展 这些修饰过的蛋白质。当前研究的主要目标是 该项目是定义和表征乙醇的影响 受体介导的内吞作用(RME)的给药过程 肝内皮细胞(LEC)可能导致肝细胞癌的发生 对修饰的自身蛋白的免疫反应。具体目标是：1) 用不同方法测定乙醇给药对RME的影响 甲醛处理的牛血清白蛋白的清道夫受体 Alb)、非酶糖化牛血清白蛋白(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)、卵蛋白(OVA)和可溶性 由肝脏摄取和代谢的免疫复合体(FCR) 2)确定肝内皮细胞是否发挥作用 在乙醛修饰的蛋白质清除中的作用，如果是这样的话，是否 长期使用乙醇会改变这一功能。此外， 诱导这种清除所需的乙醛修饰水平 将进行调查；3)确定特异性抗体 乙醛修饰的蛋白质加合物可以抑制结合和/或 生理相关乙醛修饰牛血清白蛋白的内吞作用 努力更好地表征结合部位；以及，4) 确定乙醇诱导的内吞作用减少是否会导致 乙醛修饰蛋白在肝脏中的广泛存在 内皮细胞表面以下结合到其相应的 受体。修饰的自体蛋白在LEC上的表达能力 诱导体液和/或细胞免疫反应的膜将是 下定决心。这些研究应该有助于澄清 乙醇修饰的LEC功能及其后续免疫应答的作用 在酒精性肝损伤的发病机制中起重要作用。

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.