Ethanol Effects on Antigen Presentation in Liver Cells

描述（由申请方提供）：拟定R21研究的主要目的是检查乙醇和乙醇代谢对乙醇代谢肝细胞系中抗原肽的主要组织相容性复合体（MHC）I类限制性呈递的影响。在用干扰素γ（IFN γ）活化后，这些肽被主要的抗原修剪酶（蛋白酶体和亮氨酸氨基肽酶）切割。我们先前的研究已经表明，乙醇抑制乙醇代谢HepG 2细胞中的蛋白酶体活性，并且这些乙醇处理的细胞不能适当地抑制IFN γ信号。我们假设在肝细胞中，乙醇代谢阻断IFN γ介导的信号转导。这损害了IFN γ调节的免疫蛋白酶体和亮氨酸氨基肽酶的诱导，损害了它们产生用于抗原呈递的肽的能力，并可能改变免疫应答。因此，我们提出了以下具体目的：具体目的1：研究乙醇或其代谢是否影响IFN γ诱导的肽切割，用于表达乙醇脱氢酶和细胞色素P4502 E1的小鼠重组HepB 6细胞和人重组HepG 2细胞中的MHC I类限制性抗原呈递。具体目标2：通过检测小鼠重组HepB 6细胞和人重组HepG 2细胞中乙醇引起的JAK-STAT 1信号转导途径特定组分的改变，确定乙醇暴露是否影响IFN γ介导的信号转导。具体目标3：为了确定乙醇或其代谢是否影响肝细胞的MHC I类限制性抗原呈递，使用卵清蛋白（OVA）的细胞内切割和小鼠重组HepB 6细胞表面的OVA肽SIINFEKL-H-2Kb复合物的呈递模型。这项研究的结果将阐明乙醇对肝细胞抗原呈递的影响，改变免疫反应和酒精相关的病毒性肝炎进展的可能机制之间的联系。

DESCRIPTION (provided by applicant): The major objective of the proposed R21 investigation is to examine the influence of ethanol and ethanol metabolism on major histocompatibility complex (MHC) class l-restricted presentation of antigenic peptides in ethanol-metabolizing liver cell lines. After activation with interferon gamma (IFNy), these peptides are cleaved by major antigen-trimming enzymes, the proteasome and leucine amino peptidase. Our previous investigations have indicated that ethanol suppresses proteasome activity in ethanol-metabolizing HepG2 cells, and that these ethanol-treated cells do not properly transduce the IFNy signal. We hypothesize that in liver cells, ethanol metabolism blocks IFNy-mediated signal transduction. This impairs IFNy-regulated induction of the immunoproteasome and of leucine amino peptidase, compromising their ability to generate peptides for antigen presentation and may alter immune response. We therefore propose the following Specific Aims: SPECIFIC AIM 1: To investigate whether ethanol or its metabolism affects the IFNy-induced cleavage of peptides for MHC class l-restricted antigen presentation in mouse recombinant HepB6 cells and in human recombinant HepG2 cells that express alcohol dehydrogenase and cytochrome P4502E1. SPECIFIC AIM 2: To determine whether ethanol exposure affects IFNy-mediated signal transduction by examining ethanol-elicited alterations in specific components of the JAK-STAT1 signal transduction pathway in mouse recombinant HepB6 cells and in human recombinant HepG2 cells. SPECIFIC AIM 3: To determine whether ethanol or its metabolism affects MHC class l-restricted antigen presentation by liver cells, using a model of the intracellular cleavage of ovalbumin (OVA) and the presentation of OVA peptide SIINFEKL-H-2Kb complex on the surface of mouse recombinant HepB6 cells. The results derived from this study will clarify the link between the effects of ethanol on antigen presentation by liver cells, altered immune response and the possible mechanisms of alcohol-related progression of viral hepatitis.