Regulation and impact of lipid A modification in the pathogenesis of Porphyromonas gingivalis

牙龈卟啉单胞菌是一种与牙周炎密切相关的亚革兰氏阴性细菌 牙周炎，一种慢性炎症性疾病。在健康网站中发现的人数较少，其患病率上升 在疾病期间，这表明它有很好的装备，可以在敌对的炎症条件下生存下来。动物模型有 证实了牙龈假单胞菌感染会导致牙周下菌斑的微生物失调，从而导致 炎症增加，这是牙周病的标志，标志着它是一个关键的病原体。 牙龈假单胞菌通过修饰脂质逃避受体TLR4介导的强大先天免疫反应 一种结构，具有引发大量外膜囊泡(OMV)武装的不同寻常的能力 与选定的毒力因子，如固有的宿主蛋白，破坏蛋白酶。我们已经确定了关键的 脂质A修饰基因，负责导致TLR4逃避的脂质A结构变化，以及， 此外，有助于OMV的形成。这些基因是由PGN_1123编码的脂类A脱脂酶基因， 和PG1773和PG1587，分别编码C_1-和C_4‘-磷酸酶。 在初步数据中，我们证明了这三个基因在人类体内都有较高的表达。 斑块样本的表达高于体外，而且在病变部位的表达也高于健康部位。然而， 关于这些基因如何对不同的环境条件做出反应，目前还一无所知。 接下来，我们证明A类脂磷酸酶突变体对囊泡的形成有相反的影响，提示 对PG1587和PG1773的调控调节了OMV的产量。 因此，在本申请中，将检验以下假设：“牙龈假单胞菌修饰其脂类A结构 对当地环境条件作出反应，这有助于其在体内存活和 分泌致病因子。“这一假设将通过以下三个具体目标进行检验：具体目标1。 PGN_1123、PG1587和PG1773三种脂蛋白A修饰基因的调控特征：特异性目的2. 确定牙龈假单胞菌类脂A结构及相关外膜分子对OMV的贡献 队形。具体目的3.体内脂蛋白A磷酸酶基因表达的综合分析。 这项工作将极大地促进我们对牙龈假单胞菌体内致病机制的认识。未来的研究将 包括囊泡形成所需因素的特征。总体而言，这些研究将使 控制这种Keystone病原体感染的诊断和治疗工具。

Porphyromonas gingivalis is a sub-gingival Gram-negative bacterium that is closely associated with periodontitis, a chronic inflammatory disorder. Found in low numbers in healthy sites, its prevalence increases during disease, indicating it is well equipped to survive hostile inflammatory conditions. Animal models have demonstrated that P. gingivalis infection causes microbial dysbiosis in sub-gingival plaque with an ensuing increase in inflammation, which are the hallmarks of periodontal disease, marking it as a keystone pathogen. P. gingivalis evades the powerful innate immune response mediated by the receptor TLR4 by modifying its lipid A structure and has the unusual ability to elicit copious amounts of outer membrane vesicles (OMVs) armed with select virulence factors such as innate host protein destroying proteases. We have identified the crucial lipid A modification genes which are responsible for lipid A structural changes that elicit TLR4 evasion, and, additionally, contribute to OMV formation. These genes are a lipid A deacylase gene encoded by PGN_1123, and PG1773 and PG1587, which encode lipid A C1- and C4'-phosphatases respectively. In Preliminary Data, we demonstrate that all three of these genes are expressed higher in vivo in human plaque samples than in vitro and also exhibit higher expression in diseased sites than in health. However, nothing is known concerning how these genes are regulated in response to differing environmental conditions. We next demonstrate that lipid A phosphatase mutants have opposing effects on vesicle formation, suggesting regulation of PG1587 and PG1773 modulates the amount of OMVs produced. Therefore, in this application the following hypothesis will be tested: “P. gingivalis modifies its lipid A structure in response to local environmental conditions and this contributes both to its ability to survive in vivo and secrete virulence factors.” This hypothesis will be tested by the following three Specific Aims: Specific Aim 1. Characterize regulation of PGN_1123, PG1587 and PG1773 lipid A modification genes: Specific Aim 2. Determine the contribution of P. gingivalis lipid A structure and associated outer membrane molecules on OMV formation. Specific Aim 3. Comprehensive analysis of lipid A phosphatase gene expression in vivo. This work will significantly advance our knowledge of P. gingivalis pathogenesis in vivo. Future studies will include characterization of factors required for vesiculation. Overall, these studies will enable the development of diagnostic and therapeutic tools to control infection of this keystone pathogen.