Castagliuolo I, Keates A C, Wang C C, Pasha A, Valenick L, Kelly C P, Nikulasson S T, LaMont J T, Pothoulakis C
Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
J Immunol. 1998 Jun 15;160(12):6039-45.
Neutrophil infiltration of the colonic mucosa is a hallmark of Clostridium difficile toxin A-mediated enterocolitis. Macrophage-inflammatory protein-2 (MIP-2) is a potent neutrophil chemoattractant secreted by rat macrophages and epithelial cells in response to inflammatory stimuli. In this work, we report that administration of toxin A into rat ileal loops increased mucosal levels of MIP-2 before the onset of fluid secretion and mucosal neutrophil infiltration. Administration of rabbit anti-MIP-2 IgG, but not control IgG, reduced toxin A-mediated secretion (by 58%), mucosal permeability (by 80%), and myeloperoxidase activity (by 85%). Immunohistochemical analysis demonstrated increased MIP-2 expression in intestinal epithelial and lamina propria cells 1 h after toxin A administration. Intestinal epithelial cells purified from toxin A-exposed ileal loops also showed increased MIP-2 mRNA expression and MIP-2 protein release that was inhibited by pretreatment of rats with the transcriptional inhibitor actinomycin D. These results indicate that C. difficile toxin A induces MIP-2 release from intestinal epithelial cells and that MIP-2 contributes to neutrophil mucosal influx during toxin A enteritis.
中性粒细胞浸润结肠黏膜是艰难梭菌毒素A介导的小肠结肠炎的一个标志。巨噬细胞炎性蛋白-2（MIP-2）是一种由大鼠巨噬细胞和上皮细胞在炎症刺激下分泌的强效中性粒细胞趋化因子。在本研究中，我们报告向大鼠回肠肠袢注射毒素A会在液体分泌和黏膜中性粒细胞浸润开始之前增加黏膜MIP-2水平。注射兔抗MIP-2 IgG而非对照IgG可减少毒素A介导的分泌（减少58%）、黏膜通透性（减少80%）和髓过氧化物酶活性（减少85%）。免疫组织化学分析显示，注射毒素A 1小时后，肠上皮细胞和固有层细胞中的MIP-2表达增加。从暴露于毒素A的回肠肠袢中纯化的肠上皮细胞也显示MIP-2 mRNA表达和MIP-2蛋白释放增加，而用转录抑制剂放线菌素D预处理大鼠可抑制这种增加。这些结果表明，艰难梭菌毒素A诱导肠上皮细胞释放MIP-2，并且MIP-2在毒素A肠炎期间促进中性粒细胞向黏膜内浸润。
