Cao Weibiao, Fiocchi Claudio, Pricolo Victor E
Dept. of Medicine, Brown Medical School and Rhode Island Hospital, 55 Claverick St., Rm. 337, Providence, RI 02903, USA.
Am J Physiol Cell Physiol. 2005 Dec;289(6):C1408-16. doi: 10.1152/ajpcell.00073.2005. Epub 2005 Jul 20.
We have previously shown that sigmoid circular muscle cells from patients with ulcerative colitis (UC) exhibit reduced contraction and Ca2+ signaling in response to the neurotransmitter neurokinin A (NKA) and that IL-1beta and H2O2 may contribute to these reduced responses in UC. In addition, we have found that nitric oxide (NO) levels were significantly increased in UC circular muscle. To establish the site of origin for IL-1beta, H2O2, and NO, we assembled an in vitro system in which normal or UC mucosa were sealed between two chambers filled with oxygenated Krebs solution. Because the mucosa consists of full-thickness mucosa and submucosa, it is expected that whatever is released into the undernatant from the submucosal side may diffuse to the circular muscle layer in the intact colon. Treatment of normal sigmoid circular muscle cells for 2 h with undernatants collected from the UC submucosal side (UCS) significantly decreased contraction induced by NKA and thapsigargin and the NKA- and caffeine-induced Ca2+ signal in Ca2+-free medium. In addition, UC mucosa released into the undernatant on its submucosal side significantly more H2O2, IL-1beta, and NO than normal mucosa. The reduction in contraction and Ca2+ signal induced by UCS was partially reversed by pretreatment with an IL-1beta antibody or with catalase. The NO scavenger hemoglobin partially prevented UCS-induced reduction in contraction and Ca2+ signaling in response to NKA but not the reduced response to thapsigargin or caffeine. Sodium nitroprusside inhibited NKA but not the caffeine-induced Ca2+ signal. We conclude that in UC the mucosa releases IL-1beta, H2O2, and NO, which may contribute to the impaired Ca2+ release and altered sigmoid muscle contractility.
我们之前已经表明，溃疡性结肠炎（UC）患者的乙状结肠环形肌细胞对神经递质神经激肽A（NKA）的收缩反应和Ca2+信号传导减弱，并且白细胞介素-1β（IL-1β）和过氧化氢（H2O2）可能导致UC中这些反应减弱。此外，我们发现UC环形肌中的一氧化氮（NO）水平显著升高。为了确定IL-1β、H2O2和NO的来源部位，我们构建了一个体外系统，将正常或UC黏膜密封在两个充满含氧 Krebs 溶液的腔室之间。由于黏膜由全层黏膜和黏膜下层组成，预计从黏膜下层一侧释放到下层清液中的任何物质都可能扩散到完整结肠的环形肌层。用从UC黏膜下层一侧（UCS）收集的下层清液处理正常乙状结肠环形肌细胞2小时，显著降低了NKA和毒胡萝卜素诱导的收缩以及在无钙培养基中NKA和咖啡因诱导的Ca2+信号。此外，UC黏膜在其黏膜下层一侧释放到下层清液中的H2O2、IL-1β和NO明显多于正常黏膜。用IL-1β抗体或过氧化氢酶预处理可部分逆转UCS诱导的收缩和Ca2+信号降低。NO清除剂血红蛋白部分阻止了UCS诱导的对NKA的收缩和Ca2+信号传导降低，但不能阻止对毒胡萝卜素或咖啡因的反应降低。硝普钠抑制NKA诱导的Ca2+信号，但不抑制咖啡因诱导的Ca2+信号。我们得出结论，在UC中，黏膜释放IL-1β、H2O2和NO，这可能导致Ca2+释放受损和乙状结肠肌肉收缩性改变。
