Yu Zhilun, Yue Bei, Ding Lili, Luo Xiaoping, Ren Yijing, Zhang Jingjing, Mani Sridhar, Wang Zhengtao, Dou Wei
Shanghai Key Laboratory of Formulated Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Departments of Medicine and Genetics, Albert Einstein College of Medicine, New York, NY, United States.
Front Pharmacol. 2020 Apr 21;11:474. doi: 10.3389/fphar.2020.00474. eCollection 2020.
Alpinetin is a naturally occurring flavonoid from the ginger plants. We previously reported the identification of alpinetin as a ligand of human pregnane X receptor (hPXR). The current study investigated the role of alpinetin as a putative PXR activator in ameliorating chemically induced inflammatory bowel disease (IBD). We found that oral administration of alpinetin significantly alleviated the severity of dextran sulfate sodium (DSS)-induced colitis in mice by decreasing the inflammatory infiltration, the levels of the pro-inflammatory mediators, and the PXR target genes in the colon. , alpinetin blocked the nuclear translocation of p-p65 in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Further, alpinetin significantly upregulated PXR target genes and inhibited TNF-α-induced NF-κB-luciferase activity in LS174T colorectal cells; however, this regulatory effects were lost when cellular PXR gene was knocked down. In PXR transactivation assays, alpinetin increased both mouse and human PXR transactivation in a dose-dependent manner. Ligand occluding mutants, S247W/C284W and S247W/C284W/S208W, in hPXR-reporter assays, abrogated alpinetin-induced hPXR transactivation. Finally, alpinetin bound to the hPXR-ligand-binding domain (LBD) was confirmed by competitive ligand binding assay. The current study significantly extends prior observations by validating a PXR/NF-κB regulatory mechanism governing alpinetin's anti-inflammatory effects in a murine model of IBD.
山姜素是一种天然存在的来自姜科植物的黄酮类化合物。我们之前报道了山姜素是人类孕烷X受体（hPXR）的一种配体。当前研究调查了山姜素作为一种假定的PXR激活剂在改善化学诱导的炎症性肠病（IBD）中的作用。我们发现口服山姜素可通过减少炎症浸润、促炎介质水平以及结肠中PXR靶基因，显著减轻葡聚糖硫酸钠（DSS）诱导的小鼠结肠炎的严重程度。此外，山姜素可阻断脂多糖（LPS）刺激的RAW264.7巨噬细胞中p-p65的核转位。进一步地，山姜素可显著上调LS174T结肠直肠细胞中PXR靶基因并抑制肿瘤坏死因子-α（TNF-α）诱导的NF-κB荧光素酶活性；然而，当细胞PXR基因被敲低时，这种调节作用消失。在PXR反式激活试验中，山姜素以剂量依赖性方式增加小鼠和人类PXR的反式激活。在hPXR报告基因试验中，配体封闭突变体S247W/C284W和S247W/C284W/S208W消除了山姜素诱导的hPXR反式激活。最后，通过竞争性配体结合试验证实了山姜素与hPXR配体结合域（LBD）的结合。当前研究通过在IBD小鼠模型中验证一种控制山姜素抗炎作用的PXR/NF-κB调节机制，显著扩展了先前的观察结果。
