C. elegans immune defense against the P. aeruginosa toxin Exotoxin A

描述（由申请人提供）：肠上皮细胞持续暴露于各种各样的摄入微生物，必须快速识别和防御那些致病的微生物，同时忽略微生物。如果这一过程失败，它可能导致严重和潜在的致命感染，并已与多种疾病，包括炎症性肠病和代谢综合征。尽管如此，目前尚不清楚健康的上皮细胞如何识别它们受到攻击，然后能够自卫。为了回答这些问题，我们的实验室研究了宿主/病原体的相互作用，使用小蠕虫秀丽隐杆线虫，它主要依赖于肠道上皮免疫来抵御摄入的病原体，包括革兰氏阴性菌铜绿假单胞菌。铜绿假单胞菌是一种常见的医院病原体，其对于免疫功能低下的个体如烧伤患者和囊性纤维化患者或正在接受化疗的患者尤其成问题。铜绿假单胞菌可能难以使用当前的抗生素根除，因此宿主细胞如何识别和响应这种病原体的详细表征对于开发新的治疗策略至关重要。由于细菌入侵和宿主防御的机制在进化中是高度保守的，我用相对简单易行的C。elegans模型具有直接适用于人类的高可能性。在这个应用程序中，我将研究如何C。秀丽线虫防御铜绿假单胞菌毒素外毒素A（ToxA）。ToxA是由铜绿假单胞菌产生的最有效的毒素之一，通过阻止动物细胞合成新蛋白质来杀死动物细胞。我以前发现C。线虫通过间接检测ToxA的酶促作用（翻译抑制）来识别ToxA的存在，并通过上调免疫应答基因来进行反应。令人惊讶的是，野生型C.当连续喂食ToxA时，秀丽线虫具有正常的寿命，但是在免疫信号传导途径（包括p38 MAP激酶途径）中有缺陷的动物迅速死亡。因此，健康的C.线虫动物具有一种监视机制，可以感知ToxA介导的翻译抑制并迅速产生有效的反应。本申请旨在发现如何识别蛋白质合成异常，使C。线虫生存ToxA和探索这一过程在其他生物体，包括哺乳动物模型。

DESCRIPTION (provided by applicant): Intestinal epithelial cells are continuously exposed to a wide variety of ingested microbes and must quickly recognize and defend against those that are pathogenic while simultaneously ignoring commensals. If this process fails, it can result in serious and potentially fatal infections and has been linked to multiple disorders including inflammatory bowel disease and metabolic syndrome. Despite this, it is unclear how healthy epithelial cells recognize that they are under attack and are then able to defend themselves. To answer these questions, our laboratory investigates host/pathogen interactions using the small worm Caenorhabditis elegans, which relies primarily on intestinal epithelial immunity to defend against ingested pathogens, including the gram-negative bacterium Pseudomonas aeruginosa. P. aeruginosa is a common nosocomial pathogen that is especially problematic for immunocompromised individuals such as burn victims and patients with cystic fibrosis or those undergoing chemotherapy. P. aeruginosa can be difficult to eradicate using current antibiotics and so detailed characterization of how host cells recognize and respond to this pathogen will be critical for the development of new treatment strategies. Since the mechanisms underlying bacterial invasion and host defense are strongly conserved in evolution, the discoveries I make using the relatively simple and tractable C. elegans model have a high likelihood of being directly applicable to humans. In this application, I will investigate how C. elegans defends against the P. aeruginosa toxin Exotoxin A (ToxA). ToxA is one of the most potent toxins produced by P. aeruginosa and kills animal cells by preventing them from synthesizing new proteins. I previously discovered that C. elegans recognizes the presence of ToxA by indirectly detecting its enzymatic effects (translational inhibition) and reacts by upregulating immune-response genes. Surprisingly, wild-type C. elegans have normal lifespan when continuously fed ToxA but animals defective in immune signaling pathways, including the p38 MAP kinase pathway, die rapidly. Thus, healthy C. elegans animals have a surveillance mechanism that can sense ToxA-mediated translational inhibition and quickly mount an effective response. This application seeks to discover how identifying protein synthesis abnormalities enable C. elegans to survive ToxA and to explore this process in other organisms, including mammalian models.