Mazzon Emanuela, Sautebin Lidia, Caputi Achille P, Cuzzocrea Salvatore
Department of Clinical and Experimental Medicine and Pharmacology, University of Messina, Torre Biologica, Policlinico Universitario, Messina, Italy.
Shock. 2006 Apr;25(4):377-83. doi: 10.1097/01.shk.0000209530.30564.22.
Small intestine permeability is frequently altered in inflammatory bowel disease and may be caused by the translocation of intestinal toxins through leaky small intestine tight junctions (TJs) and adherence. Recently, it has been shown that 5-lipoxygenase (5-LO) plays an important role in the development of various inflammatory conditions like inflammatory bowel disease. In the present study, by comparing the responses in wild-type mice (5-LOWT) with those of mice lacking the 5-lipoxygenase (5-LOKO), we investigated the role played by this enzyme in the permeability and structure of small intestine TJs in an animal model of experimental colitis. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). Four days after colitis induction by DNBS, the ileal TJs were studied by means of transmission electron microscopy using lanthanum nitrate and immunohistochemistry of occludin and ZO-1. When compared with DNBS-treated 5-LOWT mice, DNBS-treated 5-LOKO mice experienced a reduced rate of the extent and severity of the histological signs of colon injury. After administration of DNBS, 5-LOWT mice showed a significant increase of ileal permeability (88.3% +/- 1.2%) compared with sham (5.6% +/- 0.5%). In colitis, the percentage of "leaky" junctions in terminal ilea correlated positively with the macroscopic colon damage score. Distal colitis in 5-LOWT mice induces an increase of TJ permeability throughout the entire small intestine, and the extent of alterations correlates with colonic damage. On the contrary, a significant reduction of (1) the degree of colon injury, (2) the alteration of ZO-1 and occludin localization (immunohistochemistry), and (3) ileal permeability (8.1% +/- 0.7%) caused by DNBS in the colon was observed in 5-LOKO mice. Similarly, the treatment of 5-LOWT with zileuton (50 mg/kg per oral gavage twice a day), a 5-LO inhibitor, resulted in a significant reduction of all the previously described parameters. Taken together, our results clearly demonstrate that 5-LO modulates small intestinal permeability in experimental colitis through the regulation of TJ protein.
在炎症性肠病中，小肠通透性常常发生改变，这可能是由于肠道毒素通过渗漏的小肠紧密连接（TJs）移位和黏附所致。最近的研究表明，5-脂氧合酶（5-LO）在诸如炎症性肠病等各种炎症性疾病的发展中起着重要作用。在本研究中，通过比较野生型小鼠（5-LOWT）和缺乏5-脂氧合酶的小鼠（5-LOKO）的反应，我们在实验性结肠炎动物模型中研究了该酶在小肠紧密连接的通透性和结构中所起的作用。为了解决这个问题，我们使用了由二硝基苯磺酸（DNBS）诱导的结肠炎实验模型。在DNBS诱导结肠炎4天后，通过使用硝酸镧的透射电子显微镜和闭合蛋白及紧密连接蛋白1（ZO-1）的免疫组织化学研究回肠紧密连接。与经DNBS处理的5-LOWT小鼠相比，经DNBS处理的5-LOKO小鼠结肠损伤组织学征象的程度和严重程度的发生率降低。给予DNBS后，与假手术组（5.6%±0.5%）相比，5-LOWT小鼠回肠通透性显著增加（88.3%±1.2%）。在结肠炎中，末端回肠中“渗漏”连接的百分比与宏观结肠损伤评分呈正相关。5-LOWT小鼠的远端结肠炎导致整个小肠紧密连接通透性增加，且改变程度与结肠损伤相关。相反，在5-LOKO小鼠中观察到由结肠中的DNBS引起的（1）结肠损伤程度、（2）紧密连接蛋白1和闭合蛋白定位改变（免疫组织化学）以及（3）回肠通透性（8.1%±0.7%）显著降低。同样，用齐留通（每天两次经口灌胃50 mg/kg），一种5-脂氧合酶抑制剂，处理5-LOWT小鼠，导致所有上述参数显著降低。综上所述，我们的结果清楚地表明，5-脂氧合酶通过调节紧密连接蛋白来调节实验性结肠炎中小肠的通透性。
