Commensal Exopolysaccharide Protection from Inflammation

 描述(申请人提供)：粘膜和非粘膜部位的炎症性疾病是全世界数百万人患病的原因。我们发现，单剂量口服一种常见的益生菌枯草芽孢杆菌可以保护小鼠免受肠道病原体轮状柠檬酸杆菌感染引起的肠道炎症。枯草杆菌在轮状芽胞杆菌之后3天给药是有效的，在这个时间段，病原体已经诱导了早期的炎症过程。这些发现表明，枯草杆菌不仅可以预防炎症，更重要的是，可以减轻炎症。我们已经从枯草杆菌中鉴定和纯化了一种分子，胞外多糖(EPS)，当它自己在一次腹腔注射中引入时，可以预防由肠道病原体引起的结肠炎。EPS结合F4/80+CD11b+巨噬细胞，我们有数据表明EPS的保护作用是由M2巨噬细胞以TLR4依赖的方式介导的。此外，我们发现第二种(TLR2依赖)细胞类型是EPS保护所必需的。我们假设EPS诱导M2巨噬细胞的产生，这些巨噬细胞分泌的细胞因子要么使炎性T细胞无反应，要么诱导调节性T细胞的发展。在这里，我们将确定M2巨噬细胞是否介导保护，以及EPS是否通过TLR4信号刺激这些细胞。此外，我们将测试M2巨噬细胞是否分泌抗炎细胞因子，以及它们是否灭活T细胞或诱导调节性T细胞。最后，我们将使用三种疾病模型(食物过敏、自身免疫和炎症性肠病)来测试EPS对急性和/或慢性炎症性疾病是否有效。我们有初步数据表明，枯草杆菌和EPS可以预防影响数百万人的食物过敏。这笔赠款中提议的实验将加强我们对益生菌分子如何发挥治疗和/或预防疾病功能的分子理解，并导致治疗性益生菌小分子在人类中的合理应用。

 DESCRIPTION (provided by applicant): Inflammatory diseases at both mucosal and non-mucosal sites are responsible for disease in millions of people worldwide. We found that a single oral dose of a common probiotic bacteria, Bacillus subtilis protects mice from intestinal inflammation caused by infection with an enteric pathogen, Citrobacter rodentium. B. subtilis is effective if administered as many as 3 days after C. rodentium, a time at which the pathogen has already induced early inflammatory processes. These findings suggest that B. subtilis may not only prevent inflammation, but more importantly, attenuate it. We have identified and purified a molecule, exopolysaccharide (EPS) from B. subtilis that when introduced by itself in a single intraperitoneal injection, prevents colitis induced by enteric pathogens. EPS binds F4/80+CD11b+ macrophages, and we have data indicating that protection by EPS is mediated by M2 macrophages in a TLR4-dependent manner. Further, we found that a 2nd (TLR2-dependent) cell type is required for protection by EPS. We hypothesize that EPS induces the generation of M2 macrophages which secrete cytokines that either render inflammatory T cells non-responsive, or induce development of regulatory T cells. Here, we will establish if M2 macrophages mediate protection and if EPS stimulates these cells via TLR4 signaling. Further, we will test if M2 macrophages secrete anti-inflammatory cytokines and if they inactivate T cells or induce regulatory T cells. Finally, we will use three disease models (food allergy, autoimmunity and inflammatory bowel disease) to test if EPS is effective in acute and/or chronic inflammatory diseases. We have preliminary data indicating that B. subtilis and EPS can protect from food allergy which affects millions of people. Experiments proposed in this grant will enhance our molecular understanding of how probiotic molecules function to treat and/or prevent disease, and lead to the rational application of small therapeutic probiotic molecules to humans.