Tannerella forsythia intercations with host cells and other bacteria

描述（由申请人提供）：连翘单宁菌是一种革兰氏阴性口腔厌氧菌，与牙周病发病机制的发展有关。连翘菌仍然是最未被充分研究的牙周病原体之一，部分原因是培养这种细菌需要严格的生长要求，以及这种有机体的遗传操作直到最近才完成。此外，这种生物在动物模型中的致病性最近才有文献记载。我们在连翘中发现了一种表面相关蛋白和一种分泌蛋白BspA。BspA蛋白属于富含亮氨酸的重复序列以及细菌免疫球蛋白样超家族蛋白。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传导导致细胞骨架改变，赋予细菌入侵上皮细胞的能力。此外，BspA介导连翘与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中研究表明，BspA缺陷的连翘突变体是无毒的，这表明BspA是连翘的重要毒力因子。这项建议有以下具体目的。目的1旨在：通过toll样受体2信号传导表征bspa诱导的先天反应激活；BspA蛋白的结构功能研究；细胞受体的鉴定，包括与bspa介导的细菌进入上皮细胞相关的细胞内信号。此外，还将研究bspA基因表达的调控机制。在目的2中，将在小鼠模型中评估BspA蛋白在定植和炎症中的体内作用。此外，将确定牙周炎患者对BspA蛋白的免疫反应，以解决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中的作用和潜在机制对于制定新的牙周病干预策略至关重要。连翘单宁菌是一种革兰氏阴性口腔厌氧菌，与牙周病发病机制的发展有关，是研究最不充分的牙周病原体之一。这种细菌表达一种与细胞表面相关以及分泌的毒力因子BspA蛋白，该蛋白已被证明在细菌致病性中起重要作用。本研究旨在了解bspa诱导的牙周病发病机制，对未来牙周病治疗策略的制定具有重要意义。

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.