Probiotics:Potential Therapeutic Roles in Diarrhea

描述（由申请人提供）：益生菌微生物对人类健康具有有益作用。这些包括促进肠道屏障功能，抑制病原体感染，维持肠道稳态和免疫调节。益生菌已被用于治疗各种胃肠道疾病，包括IBD，IBS，结肠袋炎和几种类型的腹泻。腹泻可能由氯化物分泌增加、NaCl吸收受损或两者兼而有之引起。最近的研究表明，抑制病原体诱导的氯化物分泌的乳酸杆菌物种。然而，迄今为止，益生菌对肠道NaCl吸收过程的影响尚未研究。人回肠和结肠对电中性NaCl的吸收涉及肠腔Na+/H+交换和Cl-/OH-（HCO 3-）交换活动的耦合。我们假设，除了益生菌在牙周病中抑制氯化物分泌增加外，益生菌的有益作用也可能来自于刺激NaCl吸收。我们的初步研究利用Caco-2细胞单层作为人体肠道的实验模型，表现出显着增强的Cl-/OH-（HCO 3-）和Na+/H+交换活动的急性治疗乳酸杆菌，也是他们的培养上清液，这表明细菌分泌的可溶性因子参与介导这些proabsorption的影响。我们的初步研究进一步表明乳酸杆菌诱导的信号通路和运输事件的参与，详细调查所涉及的机制。目前的建议是集中在阐明的细胞和分子机制的调制管腔Cl-吸收响应乳酸杆菌在体外和体内模型中的治疗。设计了三个具体目标：1。检查正常条件下以及对肠致病性大肠杆菌感染的反应中，乳酸杆菌属物种及其分泌的可溶性因子对Caco-2和T-84（模型人结肠）细胞中氯离子转运的急性影响。coli（EPEC）; 2.研究乳酸杆菌对Cl-/OH-（HCO 3-）交换活性的调控机制，阐明乳酸杆菌对Cl-吸收的信号转导和分子运输机制。检查口服乳酸杆菌对正常小鼠肠道和结肠炎条件下由葡聚糖硫酸钠（DSS）或EPEC感染诱导的NaCl吸收的影响。我们提出的研究对于益生菌在正常和病理生理条件下调节肠道电解质吸收的作用提供新的见解至关重要，并可能为预防和治疗腹泻和炎症性疾病提供更好的策略。公共卫生相关性：益生菌是对人类健康有益的细菌。近年来，益生菌已被用于治疗各种胃肠道疾病，包括炎症性肠病和几种类型的腹泻。然而，益生菌有益作用的详细机制尚不清楚。拟议的研究对于益生菌在正常和疾病条件下调节肠道盐和水吸收的作用提供新的见解至关重要，并可能为预防和治疗腹泻和炎症性疾病提供更好的策略。

DESCRIPTION (provided by applicant): Probiotic microorganisms confer beneficial effects on human health. These include promotion of gut barrier function, inhibition of pathogen infection, maintenance of intestinal homeostasis, and immune modulation. Probiotics have been used to treat a variety of gastrointestinal ailments including IBD, IBS, pouchitis, and several types of diarrhea. Diarrhea may result from increased chloride secretion, impairment of NaCl absorption, or both. Recent studies showed inhibition of pathogen-induced chloride secretion by Lactobacillus species. To date, however, the effects of probiotics on intestinal NaCl absorptive processes have not been investigated. Electroneutral NaCl absorption in the human ileum and colon involves coupling of luminal Na+/H+ exchange and Cl-/OH-(HCO3-) exchange activities. We hypothesized that, in addition to inhibition of increased chloride secretion by probiotics in diarrheal disorders, the beneficial effects of probiotics may also arise from stimulation of NaCl absorption as well. Our preliminary studies utilizing Caco-2 cell monolayers as an experimental model for human intestine, demonstrated significant enhancement of Cl-/OH-(HCO3-) and Na+/H+ exchange activities in response to acute treatment with Lactobacilli, and also their culture supernatant, suggesting that bacteria-secreted soluble factors are involved in mediating these proabsorptive effects. Our preliminary studies further indicated involvement of Lactobacillus-induced signaling pathways and trafficking events warranting a detailed investigation of the mechanisms involved. The current proposal is focused at elucidating the cellular and molecular mechanisms underlying the modulation of luminal Cl- absorption in response to treatments with Lactobacilli in in vitro and in vivo models. Three specific aims have been designed: 1. Examine the acute effects of Lactobacillus species and their secreted soluble factors on chloride transport in Caco-2 and T-84 (model human colonic) cells under normal conditions and in response to infection with enteropathogenic E. coli (EPEC); 2. Dissect out the role of DRA and PAT1 in activation of Cl-/OH-(HCO3-) exchange activity by Lactobacilli and elucidate signaling and molecular trafficking mechanisms involved in stimulation of Cl- absorption; and 3. Examine the effects of oral administration of Lactobacilli on NaCl absorption in normal mouse intestine and under diarrheal conditions, induced by dextran sodium sulfate (DSS) or EPEC infection. Our proposed studies are critical for providing novel insights into the role of probiotics in regulating intestinal electrolyte absorption under normal and pathophysiological conditions and may provide better strategies for the prevention and treatment of diarrheal and inflammatory disorders. PUBLIC HEALTH RELEVANCE: Probiotica are bacteria that confer beneficial effects on human health. In recent years, probiotics have been used to treat a variety of gastrointestinal diseases including inflammatory bowel diseases and several types of diarrhea. However, the detailed mechanisms underlying the beneficial effects of probiotics are not known. The proposed studies are critical to provide novel insights into role of probiotics in regulating intestinal salt and water absorption under normal and disease conditions and may provide better strategies for the prevention and treatment of diarrheal and inflammatory diseases.