ALCOHOL AND LIVER ENDOTHELIAL CELLS IN IMMUNE RESPONSES

肝内皮细胞（LEC）的主要功能是通过其所谓的“清道夫”功能在宿主防御和体内平衡中，由此它们识别、内化和降解各种细胞外基质组分和修饰的蛋白质。 本实验室的报告表明，对照大鼠的LEC能够结合并降解最近表征的丙二醛-乙醛（MAA）加合物，慢性乙醇消耗导致这种配体降解为LEC的速率降低50- 60%，无论是乙醇喂养还是对照。 还显示可溶性MSS加合物导致LEC上调粘附分子（ICAM-1、VCAM-1）的表达，并增加各种细胞因子/趋化因子（TNF-α、MCP-1和MIP-2）的分泌。 因此，这些数据有力地表明，有一个家庭的受体，指定的清道夫受体，似乎介导许多的生物功能的LEC响应MAA修饰的蛋白质。 在正常条件下，MAA修饰的蛋白质似乎与LEC上的清道夫受体结合并被降解。然而，慢性乙醇消耗后，这些加合物的降解减少。 这可能导致MAA加合物与另一种受体结合，从而引发LEC中的信号级联，这可能导致炎症和/或纤维化反应的刺激。 因此，这些研究导致了这样的假设，即在慢性乙醇消耗后，肝细胞MAA修饰的蛋白质被释放到周围组织中。 然而，长期乙醇暴露改变了MAA修饰的蛋白质与其受体的结合，使得蛋白质降解减少，促炎和促纤维化介质的释放增加。 因此，本研究项目的主要目的是确定和表征LEC上负责结合MAA修饰蛋白的受体。 最初，MAA修饰的蛋白质与LEC的结合的功能后果将通过检查MAA加合物对粘附分子的表达、趋化因子/细胞因子的分泌和纤连蛋白的释放的影响来解决。 然后将使用清道夫受体的各种配体、抗体和化学抑制剂研究这种/这些受体的特异性。此外，将检查调节炎性（AP-1）中基因表达的两种因子作为MAA加合物诱导效应的介质。 最后，我们将评估MAA-加合物在已知通过慢性乙醇摄入和给予诱导脂质过氧化的药物使MAA-加合物形成永久化的动物模型中的肝毒性作用。

The major function of liver endothelial cells (LECs) is in host defense and homeostasis via their so-called "scavenger" function whereby they recognize, internalize an degrade a variety of extracellular matrix components and modified proteins. Reports from out laboratory have shown that LECs from control rats are capable of binding to and degrading the recently characterized malondialdyhyde-acetaldehyde (MAA) adduct, chronic ethanol consumption results in a 50-60 percent decrease in degradation of this ligand to LECs frm either ethanol-fed or control rates were observed. It has also been shown that soluble MSS-adducts cause LECs to upregulate the expression of adhesion molecules (ICAM-1, VCAM-1), and increase the secretion of various cytokines/chemokines (TNF-alpha, MCP-1 and MIP-2). Thus these data stronglyu suggest that there are a family of receptors, designated scavenger receptors, which appear to mediate many of the biological functions of LECs in response to MAA-modified proteins. Under normal conditions, MAA-modified proteins appear to bind to scavenger receptors on LECs and are degraded. However, following chronic ethanol consumption, there is a decrease in the degradation of these adducts. This may cause th MAA-adducts to bind to another receptor(s), thereby initiating a signal cascade in LECs that may result in the stimulation of inflammatory and/or fibrotic responses. Therefore, these studies have led to the hypothesis that following chroni ethanl consumption, hepatocyte MAA- modified protein(s) are released into the surrounding tissues. However, chronic alochol exposure alters the binding of MAA-modified proteins to its receptor(s) such that there is a decrease in protein degradation and an increased in the release of pro-inflammatory and pro-fibrotic mediators. Therefore, the principal objective of this research project is to define and characterize the receptor(s) on LECs responsible for the binding of MAA- modified proteins. Initially, the functional consequences of binding of MAA-modified proteins to LECs will be addressed by examining the effects of MAA-adducts on the expression of adhesion molecules, the secretion of the chemokines/cytokines and the release of fibronectin. The specificity of this/these receptor(s) will then be investigated using various ligands, antibodies and chemical inhibitors for scavenger receptor. Additionally, two factors regulating the expression of genes in inflammatory (AP-1) will be examined as mediators of MAA-adduct induced effects. Finally, we will evaluate the role of MAA-adducts in hepatotoxicity in animal models known to perpetuate MAA- adducts formation by way of chronic ethanol ingestion and administration of agents that induce lipid peroxidation.