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运输和屏障功能。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，我们假设当肠道屏障功能不足以排除肠道因素时，炎症性肠病就会发生，从而导致免疫刺激和炎症和损伤的恶性循环，进一步破坏运输和屏障稳态。我们还将测试益生菌微生物在基础条件下以及当肠道上皮细胞受到致病微生物或其他有害损害时对肠道上皮细胞发挥保护作用的特定假设。我们将通过解决两个具体目标来检验我们的假设。首先，我们将研究炎症性肠病小鼠模型中屏障和运输功能是否发生改变，并确定这种改变如何促进炎症的发病机制和/或症状的产生。与肠道细菌的相互作用也将被寻求。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运输功能的机制，当这些功能在体外和上述炎症性肠病模型中受损时。该方法将使用mdr1a -/-小鼠以及人类肠上皮细胞系，这些小鼠在常规饲养时发生自发性结肠炎。我们还将采用致病菌和两种具有代表性的益生菌菌株。我们将使用电生理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确定炎症的蛋白质靶点，或者是益生菌有益作用的基础。这项工作的意义在于它有可能对炎症性肠病的发病机制产生新的见解。它也可能为继续探索益生菌，有希望的补充/替代疗法，治疗炎症性肠病和其他肠道疾病提供科学依据。

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.