Brito Gerly A C, Fujji Jun, Carneiro-Filho Benedito A, Lima Aldo A M, Obrig Tom, Guerrant Richard L
Department of Morphology, Federal University of Ceará, Fortaleza, Brazil.
J Infect Dis. 2002 Nov 15;186(10):1438-47. doi: 10.1086/344729. Epub 2002 Oct 29.
This study is an investigation into the mechanism of Clostridium difficile toxin A-induced apoptosis in human intestinal epithelial cells. Toxin A induced apoptosis of T84 cells in a dose- and time-dependent fashion. Toxin A-induced apoptosis was completely inhibited by blocking toxin enzymatic activity on Rho GTPases with uridine 5'-diphosphate-2',3'-dialdehyde by a nonspecific caspase inhibitor and was partially inhibited by caspase-1, -3, -6, -8, and -9 inhibitors. Caspases 3, 6, 8, and 9 and Bid activation were detected. Toxin A also induced changes in mitochondrial membrane potential and cytochrome c release at 18-24 h, a time course similar to caspase-9 activation. In conclusion, toxin A induces apoptosis by a mechanism dependent on inactivation of Rho, activation of caspases 3, 6, 8, and 9 and Bid, and mitochondrial damage followed by cytochrome c release. Toxin A proapoptotic activity may contribute to the mucosal disruption seen in toxin A-induced enteritis.
本研究旨在探讨艰难梭菌毒素A诱导人肠上皮细胞凋亡的机制。毒素A以剂量和时间依赖性方式诱导T84细胞凋亡。用5'-二磷酸尿苷-2',3'-二醛阻断毒素对Rho GTPases的酶活性可完全抑制毒素A诱导的凋亡，非特异性半胱天冬酶抑制剂也可完全抑制，而半胱天冬酶-1、-3、-6、-8和-9抑制剂则可部分抑制。检测到半胱天冬酶3、6、8、9和Bid的激活。毒素A在18 - 24小时还诱导线粒体膜电位变化和细胞色素c释放，这一时间进程与半胱天冬酶-9激活相似。总之，毒素A通过一种依赖于Rho失活、半胱天冬酶3、6、8、9和Bid激活以及线粒体损伤随后细胞色素c释放的机制诱导凋亡。毒素A的促凋亡活性可能导致毒素A诱导的肠炎中所见的黏膜破坏。
