Riegler M, Sedivy R, Pothoulakis C, Hamilton G, Zacherl J, Bischof G, Cosentini E, Feil W, Schiessel R, LaMont J T
University Clinic of Surgery, Vienna, Austria.
J Clin Invest. 1995 May;95(5):2004-11. doi: 10.1172/JCI117885.
Toxin A but not toxin B, appears to mediate intestinal damage in animal models of Clostridium difficile enteritis. The purpose of this study was to investigate the electrophysiologic and morphologic effects of purified C. difficile toxins A and B on human colonic mucosa in Ussing chambers. Luminal exposure of tissues to 16-65 nM of toxin A and 0.2-29 nM of toxin B for 5 h caused dose-dependent epithelial damage. Potential difference, short-circuit current and resistance decreased by 76, 58, and 46%, respectively, with 32 nM of toxin A and by 76, 55, and 47%, respectively, with 3 nM of toxin B, when compared with baseline (P < 0.05). 3 nM of toxin A did not cause electrophysiologic changes. Permeability to [3H]mannitol increased 16-fold after exposure to 32 nM of toxin A and to 3 nM of toxin B when compared with controls (P < 0.05). Light and scanning electron microscopy after exposure to either toxin revealed patchy damage and exfoliation of superficial epithelial cells, while crypt epithelium remained intact. Fluorescent microscopy of phalloidin-stained sections showed that both toxins caused disruption and condensation of cellular F-actin. Our results demonstrate that the human colon is approximately 10 times more sensitive to the damaging effects of toxin B than toxin A, suggesting that toxin B may be more important than toxin A in the pathogenesis of C. difficile colitis in man.
在艰难梭菌肠炎的动物模型中，似乎是毒素A而非毒素B介导了肠道损伤。本研究的目的是在尤斯灌流小室中研究纯化的艰难梭菌毒素A和B对人结肠黏膜的电生理和形态学影响。将组织腔面暴露于16 - 65 nM的毒素A和0.2 - 29 nM的毒素B中5小时，会导致剂量依赖性的上皮损伤。与基线相比，32 nM的毒素A使电位差、短路电流和电阻分别降低了76%、58%和46%，3 nM的毒素B使它们分别降低了76%、55%和47%（P < 0.05）。3 nM的毒素A未引起电生理变化。与对照组相比，暴露于32 nM的毒素A和3 nM的毒素B后，对[3H]甘露醇的通透性增加了16倍（P < 0.05）。暴露于任一毒素后的光镜和扫描电镜检查显示，浅表上皮细胞有片状损伤和脱落，而隐窝上皮保持完整。用鬼笔环肽染色切片的荧光显微镜检查表明，两种毒素均导致细胞F - 肌动蛋白的破坏和凝聚。我们的结果表明，人结肠对毒素B损伤作用的敏感性比对毒素A高约10倍，这表明在人类艰难梭菌结肠炎的发病机制中，毒素B可能比毒素A更重要。
