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

牙龈卟啉单胞菌是一种龈下革兰氏阴性细菌，与牙龈炎密切相关。 牙周炎，一种慢性炎症性疾病。在健康的地方发现的数量很少， 在疾病期间，这表明它已经做好了在恶劣的炎症条件下生存的准备。动物模型已经 表明牙龈卟啉单胞菌感染导致龈下菌斑中的微生物生态失调， 牙周病是牙周病的一种常见病，也是牙周病的一种常见病。 P.牙龈炎通过修饰其脂质来逃避由受体TLR 4介导的强大的先天性免疫应答 一个结构，并有不寻常的能力，引起大量的外膜囊泡（OMV）武装 与选择的毒力因子如先天宿主蛋白破坏蛋白酶一起。我们已经确定了 负责引起TLR 4逃避的脂质A结构变化的脂质A修饰基因，和， 此外，有助于OMV的形成。这些基因是由PGN_1123编码的脂质A脱酰酶基因， 以及PG 1773和PG 1587，它们分别编码脂质A C1-和C4 ′-磷酸酶。 在初步数据中，我们证明了所有这三个基因在人体内的表达都较高， 斑块样品中的表达高于体外，并且在患病部位中的表达也高于健康部位。然而，在这方面， 关于这些基因如何响应于不同的环境条件而被调节，目前还不清楚。 我们接下来证明了脂质A磷酸酶突变体对囊泡形成有相反的影响，表明 PG 1587和PG 1773的调节调节产生的OMV的量。 因此，在本申请中，将测试以下假设：“牙龈卟啉单胞菌改变其脂质A结构 响应于局部环境条件，这有助于其在体内存活的能力， 分泌毒力因子。”这一假设将通过以下三个具体目标进行检验：具体目标1。 表征PGN_1123、PG 1587和PG 1773脂质A修饰基因的调控：特异性目的2。 确定牙龈卟啉单胞菌脂质A结构和相关外膜分子对OMV的贡献 阵具体目标3。脂质A磷酸酶基因在体内表达的综合分析。 这项工作将显着推进我们的知识牙龈卟啉单胞菌在体内的发病机制。未来的研究将 包括囊泡形成所需因子的表征。总的来说，这些研究将使发展 诊断和治疗工具来控制这种关键病原体的感染。

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.