Mechanism of Activation of Probiotic Bifidobacteria by Prebiotic Milk Glycans

描述(申请人提供)：益生菌和益生菌是美国公众经常使用的促进肠道健康和健康的CAM干预措施。乳酸菌和双歧杆菌等有益细菌的存在，无论是作为益生菌或通过益生菌丰富，都与积极的健康影响有关，包括减少肠道炎症、腹泻和过敏反应。然而，目前我们对这些生物效应背后的作用机制还缺乏了解。牛奶低聚糖是自然进化的益生菌底物，有助于双歧杆菌在婴儿宿主内的浓缩和相互作用。加州大学戴维斯分校牛奶生物活性计划的研究表明，婴儿携带的某些双歧杆菌菌株可以利用人乳低聚糖，这些双歧杆菌在低聚糖消费方面表现出独特的偏好。此外，对婴儿双歧杆菌和双歧双歧杆菌这两个在牛奶低聚糖上生长良好的菌株的基因组分析显示，在这些糖链上生长过程中特异地诱导了独特的基因簇。进一步的分析表明，在牛奶多糖上生长可以增强双歧杆菌与宿主上皮的相互作用。我们假设，牛奶低聚糖和同源婴儿双歧杆菌之间的进化驱动关系为增强益生菌在人类宿主内的持久性和相互作用提供了一个模型。为了解决这一假设，我们将从机制上深入了解双歧杆菌对这些独特的牛奶低聚糖的特定分解代谢，并通过以下具体目标全面了解它们对双歧杆菌-宿主相互作用的影响：1.全面表征人和牛乳低聚糖，并开发其大规模分离和生产的方法，用于功能研究。2.完整鉴定双歧杆菌转运蛋白和糖基水解酶，以分解这些复杂的牛奶低聚糖。3.检测牛奶低聚糖对双歧杆菌与宿主相互作用的影响。这些特定目标的成功完成将揭示特定的机制，人类乳寡糖通过这些机制促进双歧杆菌在母乳喂养的婴儿的胃肠道中的保护性浓缩。此外，我们将把这些发现转化为结构和功能相同的牛乳低聚糖，这是一种商业可获得的底物，可以轻松地输送到CAM食品和旨在促进肠道健康的疗法中。这一应用的意义在于从机制上更好地理解了合生元(牛奶低聚糖加同源双歧杆菌)应用的有益影响，从而为更好地解决以肠道生物失调为标志的各种疾病提供了策略和诊断措施。

DESCRIPTION (provided by applicant): Probiotics and prebiotics are CAM interventions frequently employed by the American public to promote intestinal health and wellness. The presence of beneficial bacteria such as lactobacilli and bifidobacteria, whether delivered exogenously as probiotics or enriched via prebiotics, has been linked to positive health effects including reduction of gut inflammation, diarrhea and allergic reactions. At present however, our understanding of the mechanism of action underlying these biological effects is significantly lacking. Milk oligosaccharides are naturally-evolved prebiotic substrates that facilitate bifidobacterial enrichment and interaction within the infant host. Work from the UC Davis Milk Bioactives Program has shown that human milk oligosaccharides are utilized by select infant-borne bifidobacterial strains that demonstrated unique preferences in oligosaccharide consumption. In addition, genomic analysis of Bifidobacterium infantis and Bifidobacterium bifidum, two strains that grow well on milk oligosaccharides, has revealed unique gene clusters that are specifically induced during growth on these glycans. Further analysis has revealed that growth on milk glycans results in enhanced bifidobacterial interaction with the host epithelium. We hypothesize that the evolutionarily-driven relationship between milk oligosaccharides and cognate infant-borne bifidobacteria provides a model for enhanced probiotic persistence within, and interaction with, the human host. To address this hypothesis we will gain mechanistic insight into the specific catabolism of these unique milk glycans by bifidobacteria and comprehensively map their influence on bifidobacteria-host interaction via the following Specific Aims: 1. To comprehensively characterize human and bovine milk oligosaccharides and develop methods for their large scale fractionation and production for functional studies. 2. To completely characterize the bifidobacterial transporters and glycosyl hydrolases necessary to deconstruct these complex milk oligosaccharides. 3. To examine the influence of milk oligosaccharides on the interaction between bifidobacteria and the host. Successful completion of these Specific Aims will reveal specific mechanisms by which human milk oligosaccharides facilitate a protective enrichment of bifidobacteria in the gastrointestinal tract of breast fed infants. In addition, we will translate these findings to structurally and functionally equivalent bovine milk oligosaccharides, a commercially accessible substrate that can be easily delivered into CAM foods and therapies aimed at gut health. The significance of this application is a greater mechanistic understanding of the beneficial effects of synbiotic (milk oligosaccahrides plus cognate bifidobacteria) applications thereby providing both strategies and diagnostic measures to better address a variety of disorders marked by intestinal dysbiosis.