Bacterial sialometabolic activity impacts periodontal immunity and microbiota

项目摘要/摘要。牙周炎，一种导致牙齿退化的炎症性疾病 支撑性结构经常导致牙齿脱落，是许多系统性疾病的风险因素，影响到700多人 全球有100万人，估计每年的经济负担总计4420亿美元。细菌三合一 由牙龈卟啉单胞菌、齿密螺旋体和坦纳氏菌组成的红色复合体 连翘与该病的发病机制密切相关。然而，目前还不清楚为什么 这三种病原体在牙周炎的发生发展中具有重要的作用。虽然这些细菌会产生一种 促进其定植、破坏宿主免疫和促进龈下多菌的若干因素 有趣的是，这三种病原体都会产生唾液酸酶(神经氨酸酶)--一种可以 从表皮细胞、免疫细胞和唾液中的糖蛋白中分离出末端唾液酸 牙龈沟分泌物。我们推测这些病原体的唾液酸酶活性在 先天免疫因子结构功能活性紊乱和唾液酸释放的发病机制 作为营养物质以及表面唾液酸化和合成重要细菌成分的前体，如 肽聚糖(细菌细胞壁)。在本申请中，我们将重点研究连翘唾液酸酶NanH AS 在连翘生物生存中具有独特贡献的典型病原酶 营养缺陷性为氨基糖N-乙酰胞壁酸(MurNAc)。The NanH 唾液酸酶活性可促进早期细菌-上皮细胞相互作用，导致天然免疫功能紊乱 响应，并为在生物膜中生物合成MurNAc提供了一种手段，并可能改善细菌的 通过减少对共生菌的依赖来提供MurNAc和 肽聚糖碎片。我们的假说是唾液酸和肽聚糖具有一定的觅食活性。 连翘通过促进细菌定植、生物膜健康和宿主而加重牙周炎 免疫破坏将通过：1)唾液酸酶-宿主的分子水平特征来解决 相互作用，2)确定唾液酸的代谢命运和唾液酸利用对 肽聚糖的清除和致病机制，以及3)确定微生物唾液酸酶的贡献 在调节多菌生态和炎症的同时也检测了抗菌潜力 唾液酸酶药物，如FDA批准的药物达菲(奥司他韦)，用于阻断小鼠牙周炎 模特。这项建议将采取深入的方法来定义寄主唾液糖病原体的影响 从寄主和微生物的角度来看，相互作用。它还将专注于一种新的唾液酸肽聚糖轴。 并确定这个轴对连翘适合度的影响。此外，作为原则的证明，它将 在小鼠牙周缓解模型中测试药物唾液酸酶抑制剂的治疗潜力 炎症和重塑不良生态恢复健康，并改善牙周炎疾病的结果。

Project Summary/Abstract. Periodontitis, an inflammatory disease resulting in the degradation of the tooth supporting structures often leading to tooth loss, and a risk factor for many systemic diseases, affects over 700 million people worldwide with an estimated economic burden totaling $442 billion per year. A bacterial triad known as the `red-complex' comprising of Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia is strongly implicated in the pathogenesis of the disease. However, it is not clearly understood why these three pathogens are so influential in the development of periodontitis. While these bacteria produce a number of factors to facilitate their colonization, undermine host immunity and promote subgingival polymicrobial synergy and dysbiosis, intriguingly, all three pathogens produce sialidase (neuraminidase) - an enzyme that can cleave terminal sialic acid from glycoproteins on the surface of epitheilial cells, immune cells and in salivary and gingival crevicular secretions. We hypotheisize that sialidase activity of these pathogens plays a critical role in the pathogenesis via disruption of structure-function activity of innate immune factors and liberation of sialic acid as a nutrient as well as a precursor for surface sialylation and synthesis of vital bacterial components such as peptidoglycan (bacterial cell-wall). In this application we will focus on the T. forsythia sialidase enzyme NanH as the prototypical pathogen enzyme with a unique contribution in the survival of T. forsythia - an organism auxotrophic for the peptidoglycan building block amino-sugar N-acetylmuramic acid (MurNAc). The NanH sialidase activity can promote early bacterial-epithelial cell interactions, cause disruption of innate immune responses and provide a means for the biosynthesis of MurNAc in biofilms and likely improves bacterium's survival in the subgingival niche by reducing its reliance on cohabiting bacteria to provide MurNAc and peptidoglycan fragments. Our hypothesis that sialic acid and peptidoglycan foraging activity of T. forsythia exacerbates periodontitis by promoting bacterial colonization, biofilm fitness, and host immune disruption will be addressed via: 1) Molecular level characterization of sialidase-host interactions, 2) Defining the metabolic fate of sialic acid and the impact of sialic acid utilization on peptidoglycan scavenging and pathogenesis, and 3) Determining the contribution of microbial sialidases in the modulation of polymicrobial ecology and inflammation while also examining the potential of anti- sialidase drugs such as FDA approved drugs TamiFlu (oseltamivir) in blocking periodontitis in a mouse model. This proposal will take an in-depth approach to define the influence of host sialoglycome-pathogen interactions from both the host and microbial standpoint. It will also focus on a novel sialo-peptidoglycan axis in T. forsythia and define how this axis might be critical for T. forsythia fitness. Further, as a proof of principle, it will test the therapeutic potential of pharmacological sialidase inhibitors in a mouse model to alleviate periodontal inflammation and remodel dysbiotic ecology back to health and improve periodontitis disease outcomes.