Impact of the intestinal microbiota and microbiota mediated immuneresponses on the host cell death machinery in the intestinalepithelium

先前的研究确定了一种不依赖半胱天冬酶的程序性细胞死亡模式，称为坏死性凋亡，其由ripoptosome蛋白复合物介导。在最近的一项研究中，我们可以证明caspase-8在调节肠上皮细胞坏死性凋亡和肠道免疫稳态中的关键作用。在肠上皮中条件性缺失半胱天冬酶-8（Casp 8 ΔIEC）的小鼠在回肠末端自发发生炎性病变，并且对实验诱导的结肠炎高度敏感。Casp 8 ΔIEC小鼠由于坏死性凋亡而缺乏潘氏细胞，并显示抗菌肽的表达减少，表明肠上皮的抗微生物免疫应答失调。潘氏细胞坏死是如何引发的，潘氏细胞坏死是否会引起屏障功能障碍和炎症的原因仍然是一个悬而未决的问题，是目前的proposal.As的初步数据，这一建议，我们证明了微生物植物群的组成和分布的改变。此外，我们发现在Casp 8 ΔIEC小鼠中微生物直接附着于肠上皮细胞，并且在用DSS攻击这些小鼠时细菌的系统性传播很深。因此，到目前为止，我们的数据牵连的caspase-8和潘氏细胞坏死性凋亡在调节肠道免疫稳态和抗菌defenders.The项目的总体目标是调查潘氏细胞坏死性凋亡，肠道微生物植物群和肠道炎症之间的关系。因此，我们将在不同的体外和体内系统中确定肠道微生物群对坏死性凋亡、ripoptosome复合物形成和坏死性凋亡诱导的肠道炎症的作用。我们的分析将包括常规和gnotobiotic小鼠品系，这些小鼠品系将不接受治疗或将在实验疾病模型中接受治疗，包括肠道感染和炎症模型。此外，我们将研究潘氏细胞坏死性凋亡如何影响肠道微生物植物群的组成和屏障功能。本提案中描述的项目将为肠道上皮细胞坏死性凋亡的调节及其对肠道免疫稳态的影响提供新的见解。更好地了解这些途径可能会发现治疗肠道感染和炎症的新治疗选择。

Previous studies identified a caspase-independent mode of programmed cell death, denoted necroptosis, which is mediated by the ripoptosome protein complex. In a very recent study we could demonstrate a critical role for caspase-8 in regulating necroptosis of intestinal epithelial cells and intestinal immune homeostasis. Mice with a conditional deletion of caspase-8 in the intestinal epithelium (Casp8ΔIEC) spontaneously develop inflammatory lesions in the terminal ileum and are highly susceptible to experimentally induced colitis. Casp8ΔIEC mice lack Paneth cells due to necroptosis and demonstrate decreased expression of antimicrobial peptides, suggesting dysregulated anti-microbial immune response of the intestinal epithelium. How necroptosis of Paneth cells is triggered, whether Paneth cell necroptosis induces barrier dysfunction and is causative of inflammation remains an open question and is the subject of the current proposal.As preliminary data for this proposal, we demonstrate alterations in the composition and distribution of the microbial flora. Moreover we found a direct attachment of microbes to intestinal epithelial cells in Casp8ΔIEC mice and a profound systemic spread of bacteria upon challenge of these mice with DSS. Thus, our data so far implicate a critical role of caspase-8 and Paneth cell necroptosis in regulating intestinal immune homeostasis and antimicrobial defence.The overall goal of the project is to investigate the relationship between Paneth cell necroptosis, the microbial flora of the gut and intestinal inflammation. Accordingly, we will determine the role of the intestinal microbiota on necroptosis, ripoptosome complex formation and necroptosis-induced intestinal inflammation in different in vitro and in vivo systems. Our analyses will include conventional and gnotobiotic mouse strains that will be left untreated or will be treated in experimental disease models, including models of intestinal infection and inflammation. Moreover, we will study how Paneth cell necroptosis affects the composition of the microbial flora and barrier function in the gut.The project described in this proposal will provide novel insights into the regulation of necroptosis in the intestinal epithelium and its consequences for intestinal immune homeostasis. A better understanding of these pathways might uncover new therapeutic options for the treatment of intestinal infection and inflammation.