Bakirtzi Kyriaki, West Gail, Fiocchi Claudio, Law Ivy Ka Man, Iliopoulos Dimitrios, Pothoulakis Charalabos
Inflammatory Bowel Disease Center, Division of Digestive Diseases, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California.
Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio; Department of Gastroenterology and Hepatology, Digestive Disease Institute, Cleveland Clinic Foundation, Cleveland, Ohio.
Am J Pathol. 2014 Dec;184(12):3405-14. doi: 10.1016/j.ajpath.2014.08.015. Epub 2014 Oct 7.
The expression of neurotensin (NT) and its receptor (NTR1) is up-regulated in experimental colitis and inflammatory bowel disease; NT/NTR1 interactions regulate gut inflammation. During active inflammation, metabolic shifts toward hypoxia lead to the activation of hypoxia-inducible factor (HIF)-1, which enhances vascular endothelial growth factor (VEGF) expression, promoting angiogenesis. We hypothesized that NT/NTR1 signaling regulates intestinal manifestations of hypoxia and angiogenesis by promoting HIF-1 transcriptional activity and VEGFα expression in experimental colitis. We studied NTR1 signaling in colitis-associated angiogenesis using 2,4,6-trinitrobenzenesulfonic acid-treated wild-type and NTR1-knockout mice. The effects of NT on HIF-1α and VEGFα were assessed on human colonic epithelial cells overexpressing NTR1 (NCM460-NTR1) and human intestinal microvascular-endothelial cells. NTR1-knockout mice had reduced microvascular density and mucosal integrity score compared with wild-type mice after 2,4,6-trinitrobenzenesulfonic acid treatment. VEGFα mRNA levels were increased in NCM460-NTR1 cells treated with 10(-7) mol/L NT, at 1 and 6 hours post-treatment. NT exposure in NCM460-NTR1 cells caused stabilization, nuclear translocation, and transcriptional activity of HIF-1α in a diacylglycerol kinase-dependent manner. NT did not stimulate tube formation in isolated human intestinal macrovascular endothelial cells but did so in human intestinal macrovascular endothelial cells cocultured with NCM460-NTR1 cells. Our results demonstrate the importance of an NTR1-HIF-1α-VEGFα axis in intestinal angiogenic responses and in the pathophysiology of colitis and inflammatory bowel disease.
神经降压素（NT）及其受体（NTR1）的表达在实验性结肠炎和炎症性肠病中上调；NT/NTR1相互作用调节肠道炎症。在活动性炎症期间，代谢向缺氧转变导致缺氧诱导因子（HIF）-1激活，从而增强血管内皮生长因子（VEGF）表达，促进血管生成。我们假设NT/NTR1信号通过促进实验性结肠炎中HIF-1转录活性和VEGFα表达来调节缺氧和血管生成的肠道表现。我们使用2,4,6-三硝基苯磺酸处理的野生型和NTR1基因敲除小鼠研究了结肠炎相关血管生成中的NTR1信号。在过表达NTR1的人结肠上皮细胞（NCM460-NTR1）和人肠道微血管内皮细胞上评估了NT对HIF-1α和VEGFα的影响。2,4,6-三硝基苯磺酸处理后，与野生型小鼠相比，NTR1基因敲除小鼠的微血管密度和黏膜完整性评分降低。用10(-7)mol/L NT处理的NCM460-NTR1细胞在处理后1小时和6小时时，VEGFα mRNA水平升高。NCM460-NTR1细胞暴露于NT后，以二酰基甘油激酶依赖性方式导致HIF-1α稳定、核转位和转录活性。NT在分离的人肠道大血管内皮细胞中不刺激管形成，但在与NCM460-NTR1细胞共培养的人肠道大血管内皮细胞中则刺激管形成。我们的结果证明了NTR1-HIF-1α-VEGFα轴在肠道血管生成反应以及结肠炎和炎症性肠病病理生理学中的重要性。
