Regulation of MCP-1 and chemokine receptor 2 (CCR2) in alcoholic liver disease

描述(申请人提供)：先天性免疫细胞在酒精性肝损伤的病理生理学中的重要性从动物模型和人类研究中是显而易见的。驻留在肝脏的巨噬细胞被门静脉循环中的内毒素激活，产生炎性细胞因子。除了促炎细胞因子外，巨噬细胞还产生趋化因子，这些趋化因子可能导致酒精性肝损伤。我们的初步研究表明，慢性酒精喂养后小鼠血清和肝组织MCP-1的产生增加。我们还发现，MCP-1缺陷小鼠在长期饮酒后肝损伤明显减轻。肝脏中MCP-1的增加可以促进单核/巨噬细胞在肝脏的渗透，并有助于炎症反应。单核/巨噬细胞的激活在酒精性肝损伤的发生发展中起关键作用。 我们假设，慢性酒精暴露诱导肝脏中的MCP-1及其受体CCR2促进其在肝脏中的募集。因此，MCP-1/CCR2信号的改变可能导致先天性免疫细胞介导的酒精性肝损伤。目前应用的目的是确定MCP-1/CCR2轴在酒精性肝损伤中的作用。具体地说，我们的重点将是首先对肝脏中MCP-1的表达进行纵向分析，并将这些变化与长期饮酒后肝脏驻留和渗透的巨噬细胞的变化相关联。接下来，我们将分析慢性饮酒后循环单核细胞上MCP-1受体CCR2的表达。我们还将在体外实验中确定慢性酒精对表达CCR2的单核/巨噬细胞趋化能力的影响。最后，利用CCR2基因敲除小鼠，我们将确定MCP-1/CCR2轴在酒精性脂肪肝损伤中的病理生理意义。为实现这些目标，提出了以下具体目标：1)确定酒精性肝损伤是否需要MCP-1及其细胞内机制；2)探讨慢性酒精对单核细胞/巨噬细胞CCR2受体的影响及其在酒精性肝损伤中的作用。 公共卫生相关性：酒精性肝病在美国是一个主要的健康问题。本研究旨在探讨CC-趋化因子、单核细胞趋化蛋白-1(MCP-1)及其受体CC-趋化因子受体2(CCR2)对单核/巨噬细胞进入肝脏的影响及其在酒精性肝损伤中的作用。这些机制研究将确定单核细胞和巨噬细胞的作用，并帮助开发针对慢性饮酒期间抑制巨噬细胞功能的治疗方法。

DESCRIPTION (provided by applicant): The importance of innate immune cells in the pathophysiology of alcoholic liver injury is evident from animal models and human studies. Resident macrophages in the liver are activated by endotoxin in portal circulation to produce inflammatory cytokines. In addition to the pro-inflammatory cytokines, macrophages also produce chemokines that can contribute to alcoholic liver injury. Our preliminary studies show increased production of serum and liver tissue MCP-1 production after chronic alcohol feeding in mice. We also show that MCP-1 deficient mice exhibit significantly decreased liver injury after chronic alcohol feeding. Increased MCP-1 in the liver can promote monocyte/macrophage infiltration in the liver and contribute to inflammatory responses. Activation of monocyte/macrophages is pivotal to the development of alcoholic liver injury. We hypothesize that chronic alcohol exposure induces MCP-1 in the liver and its receptor, CCR2 on circulating monocyte/macrophages facilitating their recruitment to the liver. Altered MCP-1/CCR2 signaling could thus contribute to innate immune cell-mediated alcoholic liver injury. The objectives of the current application are to determine the role of MCP-1/CCR2 axis in alcohol-induced liver injury. Specifically, our focus will be to first perform a longitudinal analysis of MCP-1 expression in the liver and correlate these changes with alterations in resident and infiltrating macrophages in the liver after chronic alcohol feeding. Next, we will analyze the MCP-1 receptor, CCR2 on circulating monocytes after chronic alcohol feeding. We will also determine the effect of chronic alcohol on chemotaxis of CCR2-expressing monocyte/macrophages in an in vitro assay. Finally, using CCR2 knock out mice we will determine the pathophysiological significance of the MCP-1/CCR2 axis in alcohol- induced fatty liver injury. To achieve these objectives, the following specific aims are proposed: 1) Determine whether MCP-1 is required for alcohol-induced liver injury and intracellular mechanisms involved and 2) Investigate the effect of chronic alcohol on CCR2, a MCP-1 receptor, on circulating monocyte/macrophages its functional significance in alcohol-induced liver injury. Public Health Relevance: Alcoholic liver disease is a major health concern in the United States. The objectives of this application are to investigate the effect of CC-chemokine, monocyte chemoattractant protein-1 (MCP-1) and its receptor CC-chemokine receptor 2 (CCR2) on monocyte/macrophages into the liver and its contribution to the development of alcoholic liver injury. These mechanistic studies will identify the role of monocytes and macrophages and aid in developing therapies targeted to inhibit macrophage function during chronic alcohol consumption.