L-Arg availability affects the physiological state of porphyromonas gingivalis

项目总结/摘要 许多慢性炎症性疾病，包括牙周感染，是基于生物膜的病理介导的 通过在复杂的宿主相关微生物群落中持续存在的土著微生物群。确定 指导口腔厌氧菌的生理状态（肠道与致病状态）的环境线索， 是牙周病治疗策略发展的基础。最近的研究表明 厌氧菌牙龈卟啉单胞菌的致病潜力不仅仅取决于其 在龈下生物膜内定植和增殖的能力;其生理状态及其与 微生物群落是病理学发展的基础。对此的核心假设是 L-精氨酸的可用性是影响牙龈卟啉单胞菌表面的关键信号/底物 易位、毒力决定簇的表达和生物膜形成。研究报告指出， 在牙周病期间，龈沟液中精氨酸水平增加2倍（从~5µM到10µM）。 这种增加的原因尚不清楚，但可能反映了微生物代谢的减少。 在某些实施方案中，精氨酸的生物合成可通过减少宿主细胞的摄取或增加细菌精氨酸生物合成来实现。一种已知 因子是由牙龈卟啉单胞菌产生的精氨酸特异性半胱氨酸蛋白酶（Arg-牙龈卟啉菌蛋白酶）的活性， 沿着其羧肽酶，该羧肽酶从由Arg-产生的肽释放末端精氨酸残基。 牙龈蛋白酶我们的分析表明，细胞内和细胞外积累的L-精氨酸有一个 对牙龈卟啉单胞菌生理学的负面影响，证实监测L-精氨酸水平， 控制。我们的研究表明，在L-精氨酸耗尽的条件下，牙龈卟啉单胞菌下调 菌毛表达，抑制生物膜形成;相反，添加L-精氨酸促进菌毛表达， 表达和表面定殖。因此，牙龈卟啉单胞菌调整其生活方式，以响应 细胞外L-精氨酸。目前尚不清楚的是控制这一点的传感和调节机制 生理上的变化。本申请的目的是确定牙龈卟啉单胞菌如何控制细胞外和细胞外的细胞毒性。 细胞内精氨酸浓度，特别是精氨酸浓度的变化对其 表面移位的能力。重要的是，已知L-精氨酸是宿主免疫的重要调节剂， 因此，我们认为，宿主和病原体对病原体的反应之间存在着微妙的平衡， 在疾病进展过程中，P. gingivalis已经进化出感知和响应精氨酸的能力， 这一关键氨基酸作为持久性的基本策略。这些研究的基本原理是， 识别控制口腔病原体的定殖和生理状态的信号将提供 治疗策略的发展目标。因此，长期目标是确定 信号传导机制可以被靶向用于治疗和预防人类生物膜诱导的疾病。

Project Summary/Abstract Many chronic inflammatory diseases, including periodontal infections, are biofilm-based pathologies mediated by indigenous microbiota persisting within complex host-associated microbial communities. Determining the environmental cues that direct the physiological state (commensal versus pathogenic state) of oral anaerobes, is fundamental to development of therapeutic strategies for periodontal diseases. Recent studies indicate that the pathogenic potential of the anaerobic bacterium Porphyromonas gingivalis is not solely dependent on its ability to colonize and proliferate within the subgingival biofilm; its physiological state and its associations within the microbial consortium are fundamental to development of pathology. The central hypothesis for this application is that the availability of L-arginine is a key signal/substrate that impacts P. gingivalis surface translocation, expression of virulence determinants, and biofilm formation. Studies have reported that the levels of arginine increase 2-fold (from ~5µM to 10µM) in gingival crevicular fluid during periodontal disease. The reason for this increase is not known but may reflect a decrease in metabolism by the microbial community, a decrease in uptake by host cells, or an increase in bacterial arginine biosynthesis. One known factor is the activity of the arginine - specific cysteine proteases (Arg-gingipains) produced by P. gingivalis, along with its carboxypeptidase that releases the terminal arginine residues from peptides produced by Arg- gingipains. Our analysis shows that both intracellular and extracellular accumulation of L-arginine has a negative impact on P. gingivalis physiology, confirming that the levels of L-arginine are monitored and controlled. Our studies have shown that under L-arginine deplete conditions, P. gingivalis down regulates expression of fimbriae, inhibiting biofilm formation; and, in contrast, addition of L-arginine boosts fimbrial expression and surface colonization. Thus, P. gingivalis adjusts its lifestyle in response to changes in extracellular L-arginine. What remains unclear is the sensing and regulatory mechanisms that control this change in physiology. The goal of this application is to determine how P. gingivalis controls extracellular and intracellular arginine concentrations and in particular the effect of changes in arginine concentration on its ability to surface translocate. Importantly, L-arginine is known to be an important modulator of the host immune response to pathogens, so we posit that there is a delicate balance between host and pathogen responses to arginine during disease progression and that P. gingivalis has evolved with the ability to sense and respond to this key amino acid as a fundamental strategy for persistence. The rationale for these studies is that identifying the signals that control colonization and the physiological state of oral pathogens will provide prime targets for the development of therapeutic strategies. Thus, the long-term objective is to determine if this mechanism of signaling can be targeted for treatment and prevention of biofilm-induced diseases in humans.