Regulation of LPS structure and function in Porphyromonas gingivalis

项目总结/摘要 牙周炎是一种高度流行的感染性炎症性疾病， 导致组织破坏、形成深牙周袋、牙槽骨吸收和牙齿脱落。 病因学模型表明，牙周炎是由一个协同的有毒细菌群落驱动的， 牙龈组织中的宿主炎症反应导致疾病进展。在公认的 病原体，革兰氏阴性厌氧菌牙龈卟啉单胞菌（Pg）已强烈牵连 牙周炎Pg菌株产生的脂多糖（LPS）大分子已被反复证明 来刺激促炎性先天免疫反应。有趣的是，Pg菌株可以使细菌的结构多样化。 LPS响应生物学相关的刺激，暂时伪装自己，逃避免疫系统， 保护免受压力，促进生存。因此，在Pg. 在与先天免疫系统的相互作用中可作为激动剂或拮抗剂的菌株。激动性LPS 通过参与TLR信号的激活，在感染的病理结果中起着重要作用 导致促炎细胞因子产生、组织破坏和骨吸收的途径。然而，在这方面， 我们还不知道LPS异质性的调节机制及其在免疫过程中的生物学重要性。 发病机制我们发现，Pg菌株具有c-di-AMP信号传导机制，其中c-di-AMP信号传导机制在Pg菌株中被激活。 合成酶PGN_0523（dacpg）和c-二-AMP磷酸二酯酶PGN_0521（pdepg）控制必需的 c-di-AMP的周转，以及因此LPS的异质性和毒力潜力。本研究将调查 c-di-AMP周转如何调节Pg LPS的异质性和免疫调节特性 和体内模型。为此，提出了两个独立但相关的具体目标：具体目标1： 了解c-di-AMP-如何控制Pg中LPS的异质性。具体目标2：了解c-di-AMP-的影响， LPS对先天性免疫应答的二AMP依赖性变化。拟议研究完成后， 我们将了解c-di-AMP信号传导如何控制Pg LPS异质性并决定先天免疫 应答由于c-di-AMP信号传导在人类中不存在，因此它是一种潜在的新型药物靶点。我们 这些发现将为发现有效的拮抗性LPS同种型提供信息，作为开发抗- 炎症治疗学。

Project Summary/Abstract Periodontitis is a highly prevalent infectious, inflammatory disease of the tissues supporting the teeth that can lead to tissue destruction, formation of a deep periodontal pocket, alveolar bone resorption, and tooth loss. Etiological models suggest that periodontitis is driven by a synergistic community of virulent bacteria that trigger host inflammatory responses in the gingival tissues resulting in disease progression. Among recognized pathogens, the Gram-negative anaerobe Porphyromonas gingivalis (Pg) has been strongly implicated in periodontitis. Lipopolysaccharide (LPS) macromolecules produced by Pg strains have been repeatedly shown to stimulate pro-inflammatory innate immune responses. Intriguingly, Pg strains can diversify the structure of LPS in response to biologically relevant stimuli to temporarily disguise themselves, evade the immune system, protect from stresses, and promote survival. Accordingly, at least four LPS variants have been identified in Pg strains that may act as agonists or antagonists in the interaction with the innate immune system. Agonistic LPS plays prominent roles in the pathological outcome of infection by being involved in the activation of TLR signaling pathways leading to production of proinflammatory cytokines, tissue destruction, and bone resorption. However, we do not yet know the mechanisms of the regulation of LPS heterogeneity and its biological importance during pathogenesis. We discovered that Pg strains possess a c-di-AMP signaling mechanism in which the c-di-AMP synthase PGN_0523 (dacpg) and the c-di-AMP phosphodiesterase PGN_0521 (pdepg) control the essential turnover of c-di-AMP, and consequently LPS heterogeneity and virulence potential. This study will investigate how c-di-AMP turnover regulates the heterogeneity and immunomodulatory properties of Pg LPS using in vitro and in vivo models. To this end, two independent but related specific aims are proposed: Specific Aim 1: To understand how c-di-AMP-controls heterogeneity of LPS in Pg. Specific Aim 2: To understand the impact of c- di-AMP-dependent variation of LPS on the innate immune response. Upon completion of the proposed studies, we will learn how c-di-AMP signaling controls Pg LPS heterogeneity and determines the innate immune responses. Since c-di-AMP signaling does not exist in humans, it is a potential novel druggable target. Our findings will inform the discovery of potent antagonistic LPS isoforms as a foundation for development of anti- inflammatory therapeutics.