Tannerella forsythia intercations with host cells and other bacteria

描述(申请人提供)：连翘坦纳氏菌是一种革兰氏阴性口腔厌氧菌，与牙周病的发病机制有关。连翘仍然是最不被研究的牙周病原体之一，部分原因是培养这种细菌需要苛刻的生长要求，以及最近才完成对这种生物的遗传操作。此外，这种微生物在动物模型中的致病性直到最近才被记录在案。我们在连翘中鉴定出一种表面相关蛋白和一种分泌型蛋白，BSPA。BSPA蛋白属于富含亮氨酸的重复序列，也属于细菌免疫球蛋白样超家族。利用体外模型系统的研究表明，BSPA蛋白通过激活Toll样受体2诱导宿主细胞释放促炎细胞因子/趋化因子，并通过激活细胞内信号导致细胞骨架变化赋予细菌侵袭上皮细胞的能力。此外，BSPA还能介导连翘与齿密螺旋体和核梭杆菌的共聚集。在细菌诱导的小鼠牙槽骨丢失模型上的研究表明，BspA缺陷的连翘突变体是无毒的，这表明BspA是连翘的一个重要毒力因子。这项建议有以下具体目标。目标1针对的是：BSPA通过Toll样受体2信号通路激活天然反应的特征；BSPA蛋白的结构功能研究；以及与BSPA介导的细菌进入上皮细胞相关的细胞受体的鉴定，包括细胞内信号转导。此外，还将探讨BSPA基因表达的调控机制。在目标2中，将在小鼠模型中评估BSPA蛋白在体内与定植和炎症相关的作用。此外，将测定牙周炎患者对BSPA蛋白的免疫反应，以说明BSPA在发病机制中的重要性。这些方法对于确定BSPA蛋白在定植和炎症中的作用将是重要的。从长远来看，了解BSPA蛋白在牙周病发病机制和潜在机制中的作用对于开发新的牙周病干预策略至关重要。连翘坦纳氏菌是一种革兰氏阴性口腔厌氧菌，参与牙周病的发病机制，是目前研究最少的牙周病原菌之一。这种细菌表达一种与细胞表面相关并分泌的毒力因子，BSPA蛋白，已被证明在细菌致病性中发挥重要作用。本申请中提出的研究旨在了解BSPA在牙周疾病中诱导发病的机制，并将对未来制定牙周病的治疗策略至关重要。

DESCRIPTION (provided by applicant): Tannerella forsythia (Bacteroides forsythus) is a gram-negative oral anaerobe implicated in the development of periodontal disease pathogenesis. T. forsythia remains one of the most understudied periodontal pathogens, partly due to the fastidious growth requirements for culturing this bacterium as well as the fact that genetic manipulation of this organism has only recently been accomplished. Moreover, the pathogenicity of this organism in animal models has only been documented recently. We identified a surface-associated as well as a secreted protein, BspA, in T. forsythia. The BspA protein belongs to the leucine-rich-repeat as well as to the bacterial immunoglobulin-like superfamilies of proteins. Studies utilizing in vitro model systems have shown that the BspA protein induces the release of proinflammatory cytokines/chemokines from host cells by activating toll- like receptor 2, as well as confers bacteria the ability to invade epithelial cells by activating intracellular signaling leading to cytoskeleton changes. In addition, BspA mediates coaggregation of T. forsythia with Treponema denticola and Fusobacterium nucleatum. Studies in a mouse model of bacterially-induced alveolar bone loss showed that a BspA-defective T. forsythia mutant was avirulent, suggesting that BspA is an important virulence factor of T. forsythia. This proposal has following specific aims. Aim 1 is directed toward: characterization of BspA-induced activation of innate responses through toll-like receptor 2 signaling; structure function studies of the BspA protein, and; identification of the cellular receptor including intracellular signaling associated with BspA-mediated bacterial entry into epithelial cells. In addition, regulatory mechanisms of bspA gene expression will be investigated. In aim 2, in vivo role of BspA protein relative to colonization and inflammation will be evaluated in a murine model. Moreover, the immune response to the BspA protein in patients with periodontitis will be determined to address the importance of BspA in pathogenesis. These approaches will be important in determining the roles of the BspA protein in colonization as well as in inflammation. In the long term, understanding the role of the BspA protein in pathogenesis and underlying mechanisms will be vital in developing novel intervention strategies against periodontal disease.Tannerella forsythia is a gram-negative oral anaerobe implicated in the development of periodontal disease pathogenesis and is one of the most understudied periodontal pathogens. This bacterium expresses a cell surface-associated as well as secreted virulence factor, the BspA protein, which has been shown to play important roles in the bacterial pathogenicity. The studies proposed in this application are aimed at understanding the mechanisms of BspA-induced pathogenesis in periodontal disease and will be vital in developing therapeutic strategies against periodontal diseases in future.