Yuan Pu-Qing, Wu S Vincent, Pothoulakis Charalabos, Taché Yvette
Center for Neurobiology of Stress, Inflammatory Bowel Disease Center, CURE: Digestive Diseases Research Center, Digestive Diseases Division, Veterans Affairs Greater Los Angeles Healthcare System, Department of Medicine and Brain Research Institute, University of California, Los Angeles, California
Center for Neurobiology of Stress, Inflammatory Bowel Disease Center, CURE: Digestive Diseases Research Center, Digestive Diseases Division, Veterans Affairs Greater Los Angeles Healthcare System, Department of Medicine and Brain Research Institute, University of California, Los Angeles, California.
Am J Physiol Gastrointest Liver Physiol. 2016 Mar 15;310(6):G387-98. doi: 10.1152/ajpgi.00337.2015. Epub 2016 Jan 7.
Urocortins (Ucns) 1, 2, and 3 and corticotropin-releasing factor receptor 2 (CRF2) mRNA are prominently expressed in various layers of the upper gut. We tested whether Ucns and CRF2 variants are also expressed in the different layers of the rat colon, regulated by LPS (100 μg/kg ip) and play a modulatory role in the colonic immune response to LPS. Transcripts of Ucns and CRF2b, the most common isoform in the periphery, were detected in all laser microdissected layers, including myenteric neurons. LPS increased the mRNA level of Ucn 1, Ucn 2, and Ucn 3 and decreased that of CRF2b in both the colonic mucosa and submucosa + muscle (S+M) layers at 2, 6, and 9 h after injection with a return to basal at 24 h. In addition, CRF2a, another variant more prominent in the brain, and a novel truncated splice variant CRF2a-3 mRNA were detected in all segments of the large intestine. LPS reciprocally regulated the colonic expression of these CRF2 variants by decreasing both CRF2a and CRF2b, while increasing CRF2a-3 in the mucosa and S+M. The CRF2 antagonist astressin2-B further enhanced LPS-induced increase of mRNA level of interleukin (IL)-1β, TNF-α, and inducible nitric oxide synthase in S+M layers and IL-1β in the mucosa and evoked TNF-α expression in the mucosa. These data indicate that Ucns/CRF2 variants are widely expressed in all colonic layers and reciprocally regulated by LPS. CRF2 signaling dampens the CD14/TLR4-mediated acute inflammatory response to Gram-negative bacteria in the colon.
尿皮质素（Ucns）1、2和3以及促肾上腺皮质激素释放因子受体2（CRF2）的信使核糖核酸（mRNA）在上消化道的不同层中显著表达。我们测试了Ucns和CRF2变体是否也在大鼠结肠的不同层中表达，是否受脂多糖（100μg/kg腹腔注射）调控，以及是否在结肠对脂多糖的免疫反应中发挥调节作用。在所有经激光显微切割的层中，包括肌间神经元，均检测到Ucns和外周最常见的异构体CRF2b的转录本。脂多糖在注射后2、6和9小时增加了结肠黏膜和黏膜下层+肌层（S+M）中Ucn 1、Ucn 2和Ucn 3的mRNA水平，并降低了CRF2b的mRNA水平，在24小时时恢复到基础水平。此外，在大肠的所有节段中均检测到另一种在脑中更突出的变体CRF2a以及一种新的截短剪接变体CRF2a-3 mRNA。脂多糖通过降低CRF2a和CRF2b，同时增加黏膜和S+M中的CRF2a-3，相互调节这些CRF2变体在结肠中的表达。CRF2拮抗剂astressin2-B进一步增强了脂多糖诱导的S+M层中白细胞介素（IL）-1β、肿瘤坏死因子-α和诱导型一氧化氮合酶的mRNA水平升高以及黏膜中IL-1β的升高，并诱发了黏膜中肿瘤坏死因子-α的表达。这些数据表明，Ucns/CRF2变体在结肠的所有层中广泛表达，并受脂多糖的相互调节。CRF2信号传导减弱了结肠中CD14/TLR4介导的对革兰氏阴性菌的急性炎症反应。
