Biagioli Michele, Carino Adriana, Cipriani Sabrina, Francisci Daniela, Marchianò Silvia, Scarpelli Paolo, Sorcini Daniele, Zampella Angela, Fiorucci Stefano
Department of Surgical and Biomedical Sciences, University of Perugia, Perugia 06132, Italy.
Department of Medicine, University of Perugia, Perugia 06132, Italy.
J Immunol. 2017 Jul 15;199(2):718-733. doi: 10.4049/jimmunol.1700183. Epub 2017 Jun 12.
GPBAR1 (TGR5 or M-BAR) is a G protein-coupled receptor for secondary bile acids that is highly expressed in monocytes/macrophages. In this study, we aimed to determine the role of GPBAR1 in mediating leukocyte trafficking in chemically induced models of colitis and investigate the therapeutic potential of BAR501, a small molecule agonist for GPBAR1. These studies demonstrated that GPBAR1 gene ablation enhanced the recruitment of classically activated macrophages in the colonic lamina propria and worsened the severity of inflammation. In contrast, GPBAR1 activation by BAR501 reversed intestinal inflammation in the trinitrobenzenesulfonic acid and oxazolone models by reducing the trafficking of Ly6C monocytes from blood to intestinal mucosa. Exposure to BAR501 shifted intestinal macrophages from a classically activated (CD11b, CCR7, F4/80) to an alternatively activated (CD11b, CCR7, F4/80) phenotype, reduced the expression of inflammatory genes (TNF-α, IFN-γ, IL-1β, IL-6, and CCL2 mRNAs), and attenuated the wasting syndrome and severity of colitis (≈70% reduction in the Colitis Disease Activity Index). The protective effect was lost in Gpbar1 mice. Exposure to BAR501 increased the colonic expression of IL-10 and TGF-β mRNAs and the percentage of CD4/Foxp3 cells. The beneficial effects of BAR501 were lost in Il-10 mice. In a macrophage cell line, regulation of IL-10 by BAR501 was GPBAR1 dependent and was mediated by the recruitment of CREB to its responsive element in the IL-10 promoter. In conclusion, GPBAR1 is expressed in circulating monocytes and colonic macrophages, and its activation promotes a IL-10-dependent shift toward an alternatively activated phenotype. The targeting of GPBAR1 may offer therapeutic options in inflammatory bowel diseases.
G蛋白偶联胆汁酸受体1(GPBAR1,又称TGR5或M-BAR)是一种在单核细胞/巨噬细胞中高表达的继发性胆汁酸G蛋白偶联受体。在本研究中,我们旨在确定GPBAR1在化学诱导的结肠炎模型中介导白细胞迁移的作用,并研究GPBAR1小分子激动剂BAR501的治疗潜力。这些研究表明,GPBAR1基因缺失增强了结肠固有层中经典活化巨噬细胞的募集,并加重了炎症的严重程度。相反,在三硝基苯磺酸和恶唑酮模型中,BAR501激活GPBAR1可通过减少Ly6C单核细胞从血液向肠黏膜的迁移来逆转肠道炎症。暴露于BAR501可使肠道巨噬细胞从经典活化(CD11b、CCR7、F4/80)表型转变为替代性活化(CD11b、CCR7、F4/80)表型,降低炎症基因(TNF-α、IFN-γ、IL-1β、IL-6和CCL2 mRNA)的表达,并减轻消瘦综合征和结肠炎的严重程度(结肠炎疾病活动指数降低约70%)。在Gpbar1基因敲除小鼠中,这种保护作用消失。暴露于BAR501可增加结肠中IL-10和TGF-β mRNA的表达以及CD4/Foxp3细胞的百分比。在Il-10基因敲除小鼠中,BAR501的有益作用消失。在巨噬细胞系中,BAR501对IL-10的调节依赖于GPBAR1,并通过CREB募集到IL-10启动子中的反应元件来介导。总之,GPBAR1在循环单核细胞和结肠巨噬细胞中表达,其激活促进向替代性活化表型的IL-10依赖性转变。靶向GPBAR1可能为炎症性肠病提供治疗选择。
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