Host-bacterial interactions, ileitis and granuloma formation in Agr2-/- mice

描述（由申请人提供）：炎症性肠病（IBD）的特征是慢性、复发性肠道炎症，产生腹泻、腹痛和营养不良的衰弱症状。其主要形式是克罗恩病和溃疡性结肠炎。克罗恩病的特征是肠壁透性炎症伴肉芽肿形成。先天免疫缺陷、自噬、内质网（ER）应激和肠道微生物菌群异常均导致克罗恩病。内质网应激诱导自噬并损害病原菌的杀伤。错误折叠的质膜和分泌的蛋白质的存在导致ER应激。蛋白质二硫键异构酶修复错误折叠的蛋白质并减少ER应激。前梯度2（AGR 2）是在肠分泌细胞和巨噬细胞中表达的蛋白质二硫键异构酶。降低其表达的人类AGR 2遗传变异与IBD风险增加相关。为了理解AGR 2在IBD中的作用，我们产生了Agr 2种系和条件性敲除小鼠。这些Agr 2-/-小鼠模型发生了剧烈的回肠炎、结肠炎、多核巨细胞和肉芽肿，这是克罗恩病患者的特征，以前在人IBD风险基因的任何小鼠模型中都没有观察到。小肠杯状细胞、潘氏细胞和巨噬细胞内质网应激增强。p62和LC 3-II是必需的自噬基因，随着AGR 2敲低而积累。重要的是，我们培养了粘膜粘附和侵袭性E。大肠杆菌（我们和其他人在克罗恩病患者的回肠中发现）来自Agr 2-/-回肠微生物群落。本项目的总体目标是了解Agr 2-/-肠上皮细胞、巨噬细胞和异常宿主微生物菌群相互作用导致多核巨细胞、肉芽肿、回肠炎和结肠炎的机制。 公共卫生相关性：我们的研究将为理解AGR 2的机制作用提供重要的新见解。我们的长期目标是确定新的信号通路和药物靶点，以改善目前IBD恶化的预防和治疗。

DESCRIPTION (provided by applicant): Inflammatory bowel disease (IBD) is characterized by chronic, relapsing intestinal inflammation producing debilitating symptoms of diarrhea, abdominal pain and malnutrition. Its main forms are Crohn's disease and ulcerative colitis. Crohn's disease is characterized by transmural intestinal inflammation with granuloma formation. Defects in innate immunity, autophagy, endoplasmic reticulum (ER) stress and abnormal enteric microflora all contribute to Crohn's disease. Endoplasmic reticulum stress induces autophagy and impairs killing of pathogenic bacteria. The presence of misfolded plasma membrane and secreted proteins causes ER stress. Protein disulfide isomerases repair misfolded proteins and reduce ER stress. Anterior Gradient 2 (AGR2) is a protein disulfide isomerase expressed in intestinal secretory cells and macrophages. Human AGR2 genetic variants that decrease its expression are associated with increased IBD risk. To understand the role of AGR2 in IBD we generated Agr2 germline and conditional knockout mice. These Agr2-/- mouse models develop dramatic ileitis, colitis, multinucleated giant cells and granulomas, a characteristic Crohn's disease patient feature that has not been previously observed in any mouse model of a human IBD risk gene. Intestinal goblet, Paneth cells and macrophages have increased ER stress. p62 and LC3-II, essential autophagy genes, accumulate with AGR2 knockdown. Importantly, we have cultured mucosally adherent and invasive E. coli (which we and others have found in the ileum of Crohn's patients) from Agr2-/- ileal microflora. The overall goal of this project is to understand the mechanism of Agr2-/- intestinal epithelia, macrophage and abnormal host microflora interaction to cause multinucleate giant cells, granulomas, ileitis and colitis. PUBLIC HEALTH RELEVANCE: Our study will provide novel insights important to understand the mechanistic roles of AGR2. Our long term goal is to identify new signaling pathways and drug targets to improve upon current IBD exacerbation prevention and therapy.