Clostridium difficile Toxin B causes epithelial cell necrosis through an autoprocessing-independent mechanism.
Clostridium difficile Toxin B causes epithelial cell necrosis through an autoprocessing-independent mechanism.
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DOI：
10.1371/journal.ppat.1003072
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发表时间：
2012
期刊：
影响因子：
6.7
通讯作者：
Lacy DB
中科院分区：
文献类型：
--
作者：
Chumbler NM;Farrow MA;Lapierre LA;Franklin JL;Haslam DB;Goldenring JR;Lacy DB
艰难梭菌是美国最常见的医院感染病原体。C.艰难梭菌分泌两种同源毒素，TcdA和TcdB，它们是导致C.艰难梭菌相关疾病毒素作用机制包括半胱氨酸蛋白酶结构域（CPD）释放葡糖基转移酶结构域（GTD）进入胞质溶胶的自动加工事件。GTD用于修饰和修饰Rho家族GTP酶。自加工在毒性中的假定重要性以及CPD活性位点的明显特异性使其潜在地成为小分子药物发现的有吸引力的靶标。在探索这种潜力的过程中，我们发现，野生型TcdB和TcdB突变体与受损的自动加工或葡糖基转移酶的活动能够诱导快速，坏死性细胞死亡的HeLa和Caco-2上皮细胞系。诱导这种表型所需的浓度与上皮损伤的猪结肠外植体模型中的病理学相关。我们的结论是，上皮细胞坏死不需要自动加工和GTD释放，并且针对TcdB的自动加工活性开发新的治疗方法不会防止C.艰难梭菌相关疾病。 艰难梭菌是一种厌氧孢子形成细菌，感染人类结肠并引起腹泻、伪膜性结肠炎和毒性巨结肠。大多数出现疾病症状的人都接受了抗生素治疗，这改变了正常的肠道植物群，使C。难以绽放。C.艰难梭菌分泌两种毒素，TcdA和TcdB，其负责与疾病相关的液体分泌、炎症和结肠组织损伤。C.与发病率和死亡率增加有关的艰难梭菌的出现突出了对新的治疗策略的需要。一种策略是抑制毒素的功能，从而减少对结肠的损伤，同时患者用抗生素清除感染。毒素的功能被认为取决于一个自动处理事件，释放毒素的催化“效应”部分进入宿主细胞。在试图鉴定抑制这种功能的小分子的过程中，我们发现TcdB诱导上皮细胞的快速坏死，这不依赖于自动加工。这一观察结果的生理相关性在结肠外植体中得到证实，并表明抑制TcdB自动加工不会防止在C.艰难梭菌相关疾病
Clostridium difficile is the most common cause of antibiotic-associated nosocomial infection in the United States. C. difficile secretes two homologous toxins, TcdA and TcdB, which are responsible for the symptoms of C. difficile associated disease. The mechanism of toxin action includes an autoprocessing event where a cysteine protease domain (CPD) releases a glucosyltransferase domain (GTD) into the cytosol. The GTD acts to modify and inactivate Rho-family GTPases. The presumed importance of autoprocessing in toxicity, and the apparent specificity of the CPD active site make it, potentially, an attractive target for small molecule drug discovery. In the course of exploring this potential, we have discovered that both wild-type TcdB and TcdB mutants with impaired autoprocessing or glucosyltransferase activities are able to induce rapid, necrotic cell death in HeLa and Caco-2 epithelial cell lines. The concentrations required to induce this phenotype correlate with pathology in a porcine colonic explant model of epithelial damage. We conclude that autoprocessing and GTD release is not required for epithelial cell necrosis and that targeting the autoprocessing activity of TcdB for the development of novel therapeutics will not prevent the colonic tissue damage that occurs in C. difficile – associated disease. Clostridium difficile is an anaerobic spore-forming bacterium that infects the human colon and causes diarrhea, pseudomembranous colitis, and toxic megacolon. Most people that develop disease symptoms have undergone antibiotic treatment, which alters the normal gut flora and allows C. difficile to flourish. C. difficile secretes two toxins, TcdA and TcdB, that are responsible for the fluid secretion, inflammation, and colonic tissue damage associated with disease. The emergence of hypervirulent strains of C. difficile that are linked to increased morbidity and mortality highlights the need for new therapeutic strategies. One strategy is to inhibit the function of the toxins, thereby decreasing damage to the colon while the patient clears the infection with antibiotics. Toxin function is thought to depend on an autoprocessing event that releases a catalytic ‘effector’ portion of the toxin into the host cell. In the course of trying to identify small molecules that would inhibit such a function, we found that TcdB induces a rapid necrosis in epithelial cells that is not dependent on autoprocessing. The physiological relevance of this observation is confirmed in colonic explants and suggests that inhibiting TcdB autoprocessing will not prevent the colonic tissue damage observed in C. difficile associated diseases.
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影响因子：
64.8
作者：
JUST, I;SELZER, J;AKTORIES, K
通讯作者：
AKTORIES, K
DOI：
10.1056/nejmra0707500
发表时间：
2008-10-30
期刊：
The New England journal of medicine
影响因子：
--
作者：
Kelly, Ciaran P;LaMont, J Thomas
通讯作者：
LaMont, J Thomas
影响因子：
3.1
作者：
DOVE, CH;WANG, SZ;JOHNSON, JL
通讯作者：
JOHNSON, JL
影响因子：
3.1
作者：
Fiorentini, C;Fabbri, A;Donelli, G
通讯作者：
Donelli, G
影响因子：
64.8
作者：
Lyras, Dena;O'Connor, Jennifer R.;Howarth, Pauline M.;Sambol, Susan P.;Carter, Glen P.;Phumoonna, Tongted;Poon, Rachael;Adams, Vicki;Vedantam, Gayatri;Johnson, Stuart;Gerding, Dale N.;Rood, Julian I.
通讯作者：
Rood, Julian I.