Unraveling strain-level variation in the induction of anti-inflammatory responses in the intestine

项目摘要：炎症性肠病(IBD)是一种日益流行的疾病，目前 在美国，大约1.3%的成年人受到影响。IBD以慢性炎性免疫反应为特征 对肠道微生物区系产生不利影响，并严重阻碍其患者的健康。当前的治疗方法 包括中和致病性炎症途径。然而，许多患者没有反应或 对治疗产生耐受性，持续服用这些药物的要求可能会增强 易受感染。一个尚未得到满足的主要临床需求需要开发改进的治疗方案。 这平息了持续的炎症，同时节省了保护性免疫力。寻求恢复宿主免疫的策略- 通过引入促进健康的免疫调节微生物(益生菌)实现肠道微生物区系的动态平衡， 代表了一种有吸引力的替代免疫功能的方法。到目前为止，这些方法有恶魔般的- 疗效有限。我们对微生物诱导抗病毒机制的不完全理解 炎症反应，以及移植的微生物如何在发炎的INTES的恶劣环境中生存- 建立一个利基市场的努力严重阻碍了这些努力。一种方法，其中最优特征来自 不同的微生物结合在一起，即所谓的设计者益生菌，代表了一种改进的治疗策略。 知识鸿沟：积极促进肠道抗炎免疫的细菌途径的认同 MUNE反应和允许益生菌菌株定植在发炎的肠道仍然是谜，因为 与肠道微生物遗传操作相关的微生物区系的复杂性和困难。假设： 不同菌株的差异影响肠道细菌物种的益生菌潜力。初步研究：至 遗传易感肠道共生菌的不同菌株的研究(一) 鉴定了B.thetaotaomicron菌株诱导积累的能力在菌株水平上的广泛变异 单克隆GnotoBiotic小鼠的结肠Tregs，(Ii)在生物膜中显示了显著的菌株水平的差异- 不同菌株的形成能力，以及(Iii)发现了一种新的B.the-the- Taiotaomicron衍生的免疫调节因子，促进抗炎细胞因子IL-2的产生 10.我们的系统提供了一个机会，利用一个物种内菌株的关联性，从而赋予不同的- 提供与益生菌最佳功能相关的途径的研究。项目ob- 目的：利用B.thetaiotaomicron的菌株水平变异和遗传易感性来定义芽孢杆菌- 最有效地赋予肠道微生物抗炎能力的rial基因和分子。影响：结果 这些研究将推动开发可提供持久缓解的设计型益生菌疗法的努力 对于IBD患者来说，这是一种疾病。目标1：确定细菌驱动的菌株水平差异的分子基础 结肠Treg诱导。目的2：定义B.thetaiotaomicron来源的免疫调节因子(S)限制 结肠炎。目的3：确定影响炎症肠道细菌菌株水平适合性的基因决定因素。

PROJECT SUMMARY: Inflammatory bowel disease (IBD) is an increasingly prevalent disease that currently affects ~1.3% of adults in the US. IBD is characterized by chronic inflammatory immune responses directed against the gut microbiota, and severely impedes the health of its sufferers. Current therapeutic approaches involve neutralization of pathogenic inflammatory pathways. However, many patients are non-responsive or become refractory to treatment, and the requirement for sustained administration of these agents can enhance susceptibility to infection. A major unmet clinical need entails development of improved therapeutic regimens that quell ongoing inflammation while sparing protective immunity. Strategies that seek to restore host immune- gut microbiota homeostasis through introduction of health-promoting immunomodulatory microbes (probiotics), represent an attractive alternative to blockade of immune function. To date, these approaches have demon- strated limited efficacy. Our incomplete understanding of the mechanisms through which microbes induce anti- inflammatory responses, and how transplanted microbes survive the hostile environment of the inflamed intes- tine to establish a niche have severely hampered these efforts. An approach where the optimal features from different microbes are combined, so-called designer probiotics, represents an improved treatment strategy. Knowledge gap: The identity of the bacterial pathways that actively promote intestinal anti-inflammatory im- mune responses and allow probiotic strains to colonize the inflamed intestine have remained enigmatic due to microbiota complexity and difficulties associated with the genetic manipulation of gut microbes. Hypothesis: Strain-specific differences impact the probiotic potential of gut bacterial species. Preliminary studies: Through the study of distinct strains of the genetically tractable gut symbiont Bacteroides thetaiotaomicron, we have (i) identified extensive strain-level variation in the ability of B. thetaiotaomicron strains to induce accumulation of colonic Tregs in monocolonized gnotobiotic mice, (ii) revealed significant strain-level variation in the biofilm- forming capacity of different strains of B. thetaiotaomicron, and (iii) uncovered the existence of a novel, B. the- taiotaomicron-derived, immunomodulatory factor that promotes production of the anti-inflammatory cytokine IL- 10. Our systems provide an opportunity to leverage the relatedness of strains within a species that impart dif- ferential phenotypes to provide insight into pathways related to the optimal function of probiotics. Project ob- jective: To leverage the strain-level variation and genetic tractability of B. thetaiotaomicron to define the bacte- rial genes and molecules that most potently confer anti-inflammatory capacity to gut microbes. Impact: Results of these studies will advance efforts to develop designer probiotic therapeutics that provide durable remission from disease for IBD patients. Aim 1: Define the molecular basis for strain-level variation in bacterial driven colonic Treg induction. Aim 2: Define the B. thetaiotaomicron-derived immunomodulatory factor(s) that limit colitis. Aim 3: Define the genetic determinants mediating bacterial strain-level fitness in the inflamed intestine.