CCR1通过ROS调控Kupffer细胞分化在NASH发展中的作用机制

Nonalcoholic fatty liver disease (NAFLD) has become a global epidemic. It is an obesity-related lipotoxic liver injury associated with hepatic lipid accumulation that can induce systemic insulin resistance and progression to nonalcoholic steatohepatitis (NASH). Chemokines and their corresponding receptors exhibiting various physiological and pathological properties have been discovered. Therefore, activating or antagonizing chemokine receptor is expected to be used for treating the related diseases. It has been reported that loss of CCR2/CCR5 prevents obesity-induced insulin resistance and NASH. However, the contribution of CCR1 to insulin resistance and NASH has yet to be determined. More recently, preliminary data have shown that CCR1 is upregulated in NASH patients. Moreover, inhibition of CCR1 by BX471 attenuated M1-markers expression and ROS production in macrophages. Thus, we anticipate that CCR1 induces Kupffer cell M1-polarization by elevating ROS generation in the progression of NASH. Utilizing the Raw264.7 cells, diet-induced NASH model of mice in combination with clinical specimens, we are going to elucidate the molecular mechanisms of CCR1 modulating the pathogenesis of NASH. Overall, our findings will not only facilitate our understanding of the molecular mechanism for CCR1 regulation of NASH, but also provide the solid basis for utilizing CCR1 signaling as the target for effective prevention and therapy of NASH.

非酒精性脂肪肝（NAFLD）已成为全球最常见的慢性疾病。它是一种与肥胖相关的脂毒性肝损伤，可引起胰岛素抵抗和慢性炎症反应，最终进展为非酒精性脂肪性肝炎（NASH）。研究表明，拮抗CCR2/CCR5信号能够显著改善肥胖诱导的胰岛素抵抗和NASH。然而，关于CCR1调控胰岛素抵抗和NASH的研究却罕有报道。我们前期研究结果表明CCR1在NASH肝脏中表达上调；CCR1拮抗剂BX471能够显著降低M1巨噬细胞标记基因的表达和ROS的产量。因此，我们推测CCR1在NASH病变过程中具有重要作用。由此提出“CCR1通过调控ROS诱导Kupffer细胞M1极化进而促进NASH的发生和发展”这一假说。我们拟在前期研究的基础上，利用细胞模型结合动物模型及临床信息，阐明CCR1调控NASH病变的分子机制。研究结果不仅有助于加深对CCR1信号通路功能的了解，而且有助于催生NASH新的防治手段。

背景和目的：非酒精性脂肪性肝病（NAFLD）是导致非酒精性脂肪性肝炎(NASH)、肝癌等严重肝脏疾病的常见临床疾病。因其发病机制尚未完全阐明，目前针对此病的日渐增长的巨大治疗需求仍无法满足。趋化因子通过与其受体相互作用能够调控各种炎性疾病的发生和发展。因此，以趋化因子及其受体为控制靶点，通过激活或拮抗趋化因子受体的信号传导来调控趋化因子系统的功能，可望用于控制和治疗相关疾病。本项目主要研究CC趋化因子受体（CCR）1对NASH的调控作用。.方法：收集临床NASH病人样本，探究CCR1的表达与NASH的相关性。使用高脂高胆固醇（CL）和胆碱缺乏（MCD）饮食诱导NASH小鼠模型，研究CCR1对NASH进程的影响。另外，开展细胞实验进一步研究CCR1对巨噬细胞的调控作用。使用CCR1特异性抑制剂BX471处理NASH小鼠，揭示抑制CCR1通路可改善NASH。.结果：CCR1在NASH病人和NASH小鼠肝脏中的表达均上调。与野生型小鼠相比，敲除CCR1能够显著降低CL或MCD饮食诱导的肝脏脂质积累、炎症及纤维化，说明敲除CCR1显著抑制小鼠NASH的进展。CCR1缺失显著抑制肝脏巨噬细胞募集和浸润，并且降低M1巨噬细胞，增加M2巨噬细胞分化。CCR1敲除显著下调炎症因子的基因表达，降低炎症信号通路的活性。相应地，在巨噬细胞中敲除CCR1显著抑制其炎症，氧化应激和M1方向极化。另外，体内或体外敲除CCR1显著抑制NASH小鼠肝脏星型细胞的活性和纤维化水平。BX471处理能够明显改善小鼠肝脏脂肪变性、炎症反应和纤维化，改善NASH的进展。.结论：敲除或抑制CCR1信号通路能够明显改善NASH，说明CCR1可能作为NASH治疗的新靶点。