Therapeutic mechanisms of L. lactis-mediated wound repair

项目概要： 使用有益细菌来促进肠道健康和限制炎症被广泛实践， 尽管实验证据证实了许多细菌的功效， 仍然有限。我们通过鉴定一种新的有益细菌来直接解决这一差距， 有效抑制损伤引起的肠道炎症。在筛选潜在的有益细菌时，我们 鉴定出乳酸乳球菌亚种cremoris作为一种细菌，引起了有效的抗炎活性， 小鼠肠。为了证实该菌株作为治疗IBD的治疗剂的用途， “早期临床试验与活生物制品”，我们将采取严格的方法，以产生关键的前， 使用结肠炎的相关小鼠模型的临床数据。我们的初步数据表明，L。甘草 慢性DSS治疗期间疾病活动指数（DAI）评分较低， 在安全和安保部撤出后恢复。机械地，我们表明，L。乳酸激活细胞保护性 NRF2信号通路的研究表明，L.乳杆菌介导的保护，或Nrf2基因 在Tlr2和Myd88缺失小鼠中不发生激活。重要的是，L.乳酸就足够了 在培养的上皮细胞的体外上皮细胞伤口愈合模型中加速愈合，这表明 由L.乳酸菌能发挥有益作用。由于L.乳酸菌ATCC 菌株不引起同样的有益效果，我们假设一个特定的因素，细菌 胞外多糖，在L. lactis是负责引发其强大的抗炎和促恢复 通过MyD88依赖性信号传导的作用。此外，我们还展示了新的初步数据，L。乳酸激活 肠组织中一组特定microRNA的表达，与NRF2的调节相关 信号通路因此，我们的中心假设是，由L. lactis 在肠道中诱导细胞保护和抗炎作用，并可调节 IBD。我们将在以下具体目标中检验我们的假设：（1）描述 L. lactis subsp.（2）确定L. cremoris在结肠炎中产生和释放的因子。lactis subsp. cremoris 诱导其有益作用并激活NRF2信号传导，以及（3）确定关键L. lactis 亚种Cremoris诱导的调节NRF2信号转导的microRNAs在调节L. lactis subsp.奶油总之，我们确定了一种效应微生物， 表型，对抑制结肠炎诱导的炎症具有明显的有利作用。我们会发现 潜在的作用机制，这已成为微生物组研究的焦点，这是必不可少的 微生物群疗法的发展。我们打算为L的使用生成足够的数据。lactis 亚种Cremoris在临床试验中用于治疗由异常炎症表现的消化系统疾病。

PROJECT SUMMARY: The use of beneficial bacteria to promote intestinal health and to limit inflammation is widely practiced, although experimental evidence corroborating the efficacy of many bacteria promoted with such claims remains limited. We directly address this gap by identifying a newly characterized beneficial bacterium that potently dampens injury-induced intestinal inflammation. In a screen of potential beneficial bacteria, we identified Lactococcus lactis subsp. cremoris as a bacterium that elicited potent anti-inflammatory activity in the mouse intestine. In order to substantiate the use of this strain as a therapeutic to treat IBD, which is required ‘Early Clinical Trial with Live Biotherapeutic Products’, we will take a rigorous approach to generate critical pre- clinical data using relevant mouse models of colitis. Our preliminary data show that feeding of L. lactis elicits lower Disease Activity Index (DAI) scores during chronic DSS treatment, and a significantly faster rate of recovery following the withdrawal of DSS. Mechanistically, we show that L. lactis activates the cytoprotective NRF2 signaling pathway in intestinal tissue, and show here that L. lactis-mediated protection, or Nrf2 gene activation does not occur in Tlr2 & Myd88-null mice. Importantly, culture supernatant of L. lactis was sufficient to accelerate healing in an in vitro epithelial cell wound healing model in cultured epithelial cells, indicating that a factor secreted by L. lactis elicits the beneficial effects. Because phylogenetically related L. lactis ATCC strains do not elicit the same beneficial effects, we hypothesize that a specific factor, bacterial exopolysaccharide, within L. lactis is responsible for eliciting its powerful anti-inflammatory and pro-restitutive effects via MyD88-dependent signaling. In addition, we show novel preliminary data that L. lactis activates the expression of a specific set of microRNAs in intestinal tissue that are associated with the regulation of NRF2 pathway signaling. Therefore, our central hypothesis is that the specific element(s) released by L. lactis induces cytoprotective and anti-inflammatory effects in the intestine, and can modulate the pathobiology of IBD. We will test our hypothesis in the following specific aims: (1) to characterize the pro-restitutive effects of L. lactis subsp. cremoris in colitis, (2) to identify the factor produced and released by L. lactis subsp. cremoris that induces its beneficial effects and activates NRF2 signaling, and (3) to determine the role of key L. lactis subsp. cremoris-induced microRNAs that regulate NRF2 signaling in modulating the cytoprotective effects of L. lactis subsp. cremoris. Together, we identify an effector microorganism that beneficially influences host phenotype, with clear favorable effects on dampening colitis-induced inflammation. We will discover the underlying mechanisms of action, which has become foci of microbiome research, and which is essential for the development of microbiota-based therapeutics. We intend to generate sufficient data for the use of L. lactis subsp. cremoris in clinical trials to treat digestive diseases manifested by aberrant inflammation.