IRE1beta links the gut microbiota and epithelial differentiation to protect against colitis

项目摘要 溃疡性结肠炎(UC)是一种常见的慢性炎症性肠病，以表浅为特征 结肠和直肠上皮的炎症和损伤。虽然UC的原因尚不清楚，但遗传因素 研究指出不适当的免疫信号、肠道微生物区系的错误处理以及上皮修复的改变 作为促成因素的机制。UC的一个共同特征是结肠内粘液层的改变。 上皮细胞，可能是由于粘蛋白生物合成的改变以及杯状物分化的缺陷 细胞。由于粘液层通常作为保护性的先天免疫屏障，将微生物与 上皮表面，粘液组装的缺陷使肠道细菌更多地与结肠上皮接触 非常接近。这与触发免疫反应或增加感染的易感性有关， 对加州大学的病理生理学有贡献。内质网应激和未折叠蛋白反应与分泌密切相关 肠上皮的细胞功能和炎症。肠上皮和其他粘膜上皮 它们的独特之处在于它们表达了一种额外的内质网应激传感器，称为IRE1β。IRE1β似乎能保护人类免受 结肠损伤和炎症的机制不明。我们最近发现，ir1的β在 在肠上皮细胞中展开蛋白质反应，并发现IRE1β-/-小鼠的结肠紧密 看起来像人类UC。与IRE1β+/+相比，IRE1β-/-小鼠结肠中成熟杯状细胞较少 一窝产仔。这与放置肠道微生物区系的几乎被废除的内部粘液层有关。 紧邻结肠上皮。在稳态条件下，IRE1β-/-结肠隐窝不 表达UPR升高的标志物，表明未解决的内质网应激不能解释这种表型。 相反，似乎ir1β是表达指定杯状细胞的转录因子所必需的。 发展。值得注意的是，我们发现ir1β的表达和结肠粘液层的组装受到 肠道微生物区系。这些数据将Ire 1β的S功能置于微生物区系和上皮细胞的交界处， 调节保护宿主免受炎症信号和感染的先天屏障。这样做的目的是 格兰特的任务是了解IRE1β如何预防结肠炎，我们的中心假设是IRE1β预防 通过控制微生物区系诱导的杯状细胞分化和结肠粘液的组装来防治结肠炎 一层。我们将使用体外和体内模型来了解微生物区系如何调节IRE1β功能(AIM 1)，定义IRE1β如何调节杯状细胞分化(目标2)，并建立IRE1β功能的相关性 在实验模型和人类UC中预防结肠炎(目标3)。

Project Summary Ulcerative colitis (UC) is a common, chronic form of inflammatory bowel disease characterized by superficial inflammation and damage to the epithelium of the colon and rectum. While causes of UC are unknown, genetic studies point to inappropriate immune signaling, mishandling of the gut microbiota, and altered epithelial repair mechanisms as contributing factors. A common feature of UC is an altered mucus layer in the colon epithelium, which may be due to changes in mucin biosynthesis as well as to defects in differentiation of goblet cells. As the mucus layer normally serves as a protective innate immune barrier, separating microbes from the epithelial surface, defects in mucus assembly allow gut bacteria to interface with the colonic epithelium more closely. This has been implicated in triggering immune responses or increasing susceptibility to infections that contribute to UC pathophysiology. ER stress and the unfolded protein response is intimately linked to secretory cell function and inflammation in the intestinal epithelium. The intestinal epithelium and other mucosal epithelia are unique in that they express an additional ER stress sensor called IRE1β. IRE1β appears to protect against colonic injury and inflammation by unknown mechanisms. We recently found that IRE1β functions in the unfolded protein response in intestinal epithelial cells, and discovered that the colon of IRE1β-/- mice closely resembles human UC. IRE1β-/- mice have fewer mature goblet cells in the colon compared to IRE1β+/+ littermates. This is associated with a nearly abolished inner mucus layer that places the gut microbiota immediately adjacent to the colonic epithelium. Under steady state conditions IRE1β-/- colonic crypts do not express elevated markers of a UPR, suggesting that unresolved ER stress cannot explain this phenotype. Instead, it appears that IRE1β is required for expression of transcription factors that specify goblet cell development. Notably, we find IRE1β expression and assembly of the colon mucus layer are stimulated by the gut microbiota. These data place IRE1β's function at the interface of the microbiota and the epithelium, regulating the innate barrier that protects the host from inflammatory signals and infection. The purpose of this grant is to understand how IRE1β protects against colitis, where our central hypothesis is IRE1β protects against colitis by controlling microbiota-induced goblet cell differentiation and assembly of the colon mucus layer. We will use in vitro and in vivo models to understand how the microbiota regulates IRE1β function (Aim 1), define how IRE1β regulates goblet cell differentiation (Aim 2), and establish the relevance of IRE1β function in protecting against colitis in experimental models and human UC (Aim 3).