Department and Graduate Institute of Biomedical Sciences, and Healthy Aging Research Center, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan.
Department and Institute of Physiology, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan.
Int J Mol Sci. 2022 Oct 27;23(21):13048. doi: 10.3390/ijms232113048.
C-C chemokine receptor type 5 (CCR5) positively contributes to the pathogenesis of nonalcoholic fatty liver disease (NAFLD), a common metabolic liver disease associated with chronic inflammation. CCR5 signaling also facilitates the immunosuppressive activity of a group of immature myeloid cells known as granulocytic myeloid-derived suppressor cells (g-MDSCs). While both hepatocyte and g-MDSC express CCR5, how CCR5 coordinates these two distinct cell types in the hepatic microenvironment remains largely unknown. Here, we used in vivo and ex vivo approaches to define the molecular details of how CCR5 mediates the crosstalk between hepatocytes and g-MDSCs in a mouse model of NAFLD. Global CCR5-deficient mice exhibited more severe steatosis, increased hepatic gene expression of lipogenesis, and exacerbated liver damage in diet-induced obesity. Either NAFLD or CCR5-deficiency per se is causative for the increase of g-MDSCs. Purified g-MDSCs have a higher survival rate in the fatty liver microenvironment, and blockade of CCR5 significantly decreases g-MDSCs' expression of anti-inflammatory factors. On the other hand, the null of CCR5 signaling increases hepatocytes' expression of lipogenic genes in the NAFLD microenvironment. Most importantly, inhibiting g-MDSCs' CCR5 signaling in the fatty liver microenvironment dramatically reduces STAT3 signaling, lipogenic, and pro-inflammatory gene expression in primary hepatocytes. Adoptive cell transfer experiments further demonstrate that CCR5-deficient g-MDSCs mitigate hepatic lipogenic gene expression without facilitating pro-inflammatory cytokine production and liver damage in NAFLD mice. These results suggest that targeting g-MDSCs' CCR5 signaling might serve as a potential therapeutic strategy for NAFLD.
C-C 趋化因子受体 5(CCR5)正向促进非酒精性脂肪性肝病(NAFLD)的发病机制,NAFLD 是一种与慢性炎症相关的常见代谢性肝病。CCR5 信号还促进了一组称为粒细胞髓源抑制细胞(g-MDSC)的不成熟髓样细胞的免疫抑制活性。虽然肝细胞和 g-MDSC 都表达 CCR5,但 CCR5 如何协调肝微环境中的这两种不同细胞类型在很大程度上尚不清楚。在这里,我们使用体内和体外方法来定义 CCR5 在 NAFLD 小鼠模型中如何介导肝细胞和 g-MDSC 之间串扰的分子细节。全身性 CCR5 缺陷小鼠表现出更严重的脂肪变性、肝内脂肪生成基因表达增加和饮食诱导肥胖引起的肝损伤加剧。NAFLD 或 CCR5 缺陷本身会导致 g-MDSC 增加。在脂肪肝微环境中,纯化的 g-MDSC 具有更高的存活率,而 CCR5 阻断显著降低了 g-MDSC 抗炎因子的表达。另一方面,CCR5 信号的缺失增加了 NAFLD 微环境中肝细胞的脂肪生成基因表达。最重要的是,在脂肪肝微环境中抑制 g-MDSC 的 CCR5 信号显著降低了原代肝细胞中 STAT3 信号、脂肪生成和促炎基因的表达。细胞转移实验进一步表明,在 NAFLD 小鼠中,缺乏 CCR5 的 g-MDSC 减轻肝脏脂肪生成基因表达,而不促进促炎细胞因子的产生和肝损伤。这些结果表明,靶向 g-MDSC 的 CCR5 信号可能是治疗 NAFLD 的一种潜在治疗策略。
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