Thibault Ronan, De Coppet Pierre, Daly Kristian, Bourreille Arnaud, Cuff Mark, Bonnet Christian, Mosnier Jean-François, Galmiche Jean-Paul, Shirazi-Beechey Soraya, Segain Jean-Pierre
UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA, Université de Nantes, Nantes, France.
Gastroenterology. 2007 Dec;133(6):1916-27. doi: 10.1053/j.gastro.2007.08.041. Epub 2007 Aug 22.
BACKGROUND & AIMS: Butyrate oxidation is impaired in intestinal mucosa of patients with inflammatory bowel diseases (IBD). Butyrate uptake by colonocytes involves the monocarboxylate transporter (MCT) 1. We aimed to investigate the role of MCT1 in butyrate oxidation deficiency during colonic inflammation.
Colonic tissues were collected from patients with IBD or healthy controls and from rats with dextran sulfate sodium (DSS)-induced colitis. The intestinal epithelial cell line HT-29 was treated with interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). MCT1 expression was analyzed by real-time reverse-transcription polymerase chain reaction, Western blot, and immunofluorescence. Butyrate uptake and oxidation in HT-29 cells was assessed using [(14)C]-butyrate. The mechanism of MCT1 gene regulation was analyzed by nuclear run-on and reporter gene assays.
MCT1 messenger RNA (mRNA) and protein levels were markedly decreased in inflamed colonic mucosa of IBD patients and rats. In HT-29 cells, down-regulation of MCT1 mRNA and protein abundance by IFN-gamma and TNF-alpha correlated with a decrease in butyrate uptake and subsequent oxidation. IFN-gamma and TNF-alpha did not affect MCT1 mRNA stability but rather down-regulated gene transcription. We demonstrate that the cytokine response element is located in the proximal -111/+213 core region of the MCT1 promoter.
The data suggest that butyrate oxidation deficiency in intestinal inflammation is a consequence of reduction in MCT1-mediated butyrate uptake. This reinforces the proposition that butyrate oxidation deficiency in IBD is not a primary defect.
炎症性肠病（IBD）患者的肠黏膜中丁酸氧化受损。结肠细胞对丁酸的摄取涉及单羧酸转运体（MCT）1。我们旨在研究MCT1在结肠炎症期间丁酸氧化缺陷中的作用。
收集IBD患者或健康对照者以及葡聚糖硫酸钠（DSS）诱导的结肠炎大鼠的结肠组织。用干扰素-γ（IFN-γ）和肿瘤坏死因子-α（TNF-α）处理肠上皮细胞系HT-29。通过实时逆转录聚合酶链反应、蛋白质印迹和免疫荧光分析MCT1的表达。使用[¹⁴C] -丁酸评估HT-29细胞中丁酸的摄取和氧化。通过核转录和报告基因分析来分析MCT1基因调控的机制。
IBD患者和大鼠发炎的结肠黏膜中MCT1信使核糖核酸（mRNA）和蛋白质水平显著降低。在HT-29细胞中，IFN-γ和TNF-α导致的MCT1 mRNA和蛋白质丰度下调与丁酸摄取及随后的氧化减少相关。IFN-γ和TNF-α不影响MCT1 mRNA的稳定性，而是下调基因转录。我们证明细胞因子反应元件位于MCT1启动子的近端-111 / +213核心区域。
数据表明肠道炎症中丁酸氧化缺陷是MCT1介导的丁酸摄取减少的结果。这强化了IBD中丁酸氧化缺陷不是原发性缺陷的观点。
