PATHOGENS, PROBIOTICS AND THE EPITHELIUM IN COLITIS

描述（由申请人提供）：我们的长期目标是了解肠上皮转运和屏障功能。大量证据表明，这些关键功能在炎症性肠病和其他肠道疾病的情况下发生改变。此外，我们假设炎症性肠病的结果时，肠屏障功能不足以排除管腔因子，从而导致免疫刺激和炎症和损伤的恶性循环，进一步损害运输和屏障稳态。我们还将测试特定的假设，即益生菌微生物在基础条件下以及当它们受到病原微生物或其他有害的损伤时对肠上皮细胞发挥保护作用。我们将通过解决两个具体目标来验证我们的假设。在第一，我们将检查是否屏障和运输功能改变炎症性肠病的小鼠模型，已知依赖于上皮缺损，并确定如何改变有助于炎症的发病机制和/或生成的炎症。也将寻求与管腔细菌的相互作用。在第二个目标中，我们将定义益生菌微生物在控制条件下改善上皮屏障和转运功能的机制，当这些功能在体外和上述炎性肠病模型中受损时。该方法将使用mdr1a-/-小鼠，该小鼠在常规饲养时发生自发性结肠炎，以及人类肠上皮细胞系。我们还将使用致病菌和两种代表性的益生菌菌株。我们将使用电生理学方法研究这些模型中的运输和屏障功能，并将应用分子技术来定义炎症的蛋白质靶点，或益生菌有益作用的基础。这项工作的意义在于它有可能产生新的见解炎症性肠病的发病机制。它还可以为继续探索益生菌提供科学依据，益生菌是治疗炎症性肠病和其他肠道疾病的有希望的补充/替代疗法。

DESCRIPTION (provided by applicant): Our long-term goal is to understand intestinal epithelial transport and barrier function. Substantial evidence suggests that these critical functions are altered in the setting of inflammatory bowel disease and other intestinal disorders. Moreover, we hypothesize that inflammatory bowel disease results when intestinal barrier function is inadequate to exclude luminal factors, thereby resulting in immune stimulation and a vicious cycle of inflammation and injury that further compromises transport and barrier homeostasis. We will also test the specific hypothesis that probiotic microorganisms exert protective effects on intestinal epithelial cells under both basal conditions and when they are compromised by pathogenic microorganisms or other injurious insults. We will test our hypotheses by addressing two Specific Aims. In the first, we will examine whether barrier and transport functions are altered in a mouse model of inflammatory bowel disease known to depend on an epithelial defect, and determine how such alterations contribute to the pathogenesis of inflammation and/or the generation of symptomatology. The interplay with luminal bacteria will also be sought. In the second Aim, we will define mechanisms whereby probiotic microorganisms improve epithelial barrier and transport function under control conditions, when these functions are compromised in vitro, and in the model of inflammatory bowel disease described above. The approach will be to use the mdr1a -/- mouse which develops spontaneous colitis when conventionally housed, as well as human intestinal epithelial cell lines. We will also employ pathogenic bacteria and two representative probiotic strains. We will study transport and barrier functions in these models using electrophysiological approaches, and will apply molecular techniques to define protein targets of inflammation, or which underlie the beneficial effects of probiotics. The significance of this work lies in its potential to yield novel insights into the pathogenesis of inflammatory bowel disease. It may also provide a scientific rationale for continued exploration of probiotics, promising complementary/alternative therapies, in the treatment of inflammatory bowel disease and other intestinal disorders.