P. gingivalis Mediated Evasion Strategies

描述（由申请人提供）：许多成功的病原体已经进化出逃避宿主防御的机制，从而建立持续和慢性感染。口腔病原体牙龈卟啉单胞菌慢性感染的标志是诱导慢性炎症反应。尽管膜结合的先天性免疫受体（包括Toll样受体（TLR））在响应牙龈卟啉单胞菌的炎症中起作用，但尚不清楚针对该病原体的细胞内宿主防御机制如何促成持续感染并导致慢性炎症。我们最近报道了一种新的策略，牙龈卟啉单胞菌通过这种策略调节参与细胞死亡和宿主防御反应的关键细胞内蛋白质的水平。我们证明牙龈卟啉单胞菌的赖氨酸特异性细菌半胱氨酸蛋白酶（牙龈菌蛋白酶K-Kgp）诱导受体相互作用蛋白激酶1（RIPK 1）和RIPK 2的蛋白水解。我们的初步研究揭示了牙龈卟啉单胞菌介导的RIPK降解对细胞内免疫信号转导应答的功能后果。这些研究支持了病原体介导的慢性炎症性疾病是由特定病原体介导的逃避策略导致的低度慢性炎症这一新兴概念。鉴于RIPK在TNF-R诱导的细胞活化和细胞内病原体的感应中的作用，我们提出牙龈卟啉单胞菌瞬时降解RIPK功能的能力作为避免细胞内先天免疫信号传导的机制，并允许细菌在靶细胞内持续存在。以下具体目标将检验这一假设：目标1。确定Kgp介导的RIPK降解对先天免疫信号传导和细菌持久性的功能后果;目的2。为了表征RIPK裂解产物在抑制NF？B激活; Aim 3.评估牙龈卟啉菌蛋白酶在鼠模型中抑制牙龈卟啉单胞菌诱导的局部部位慢性炎症的效率;以及目的4.在ApoE-/-小鼠模型中评估牙龈卟啉菌蛋白酶抑制剂对牙龈卟啉单胞菌诱导的全身部位慢性炎症的抑制效率。特异性阻断Kgp介导的细胞激酶修饰的能力代表了靶向宿主细胞内细菌持久性和先天免疫信号传导的新策略。成功进行拟议的研究有可能确定和验证新的治疗干预措施，目标是与慢性感染和由此产生的炎症后遗症相关的病原体逃避机制。

DESCRIPTION (provided by applicant): A number of successful pathogens have evolved mechanisms to evade host defense, thus establishing persistent and chronic infections. A hallmark of chronic infection with the oral pathogen, Porphyromonas gingivalis, is the induction of a chronic inflammatory response. Although membrane- bound innate immune receptors, including Toll-like receptors (TLR), play a role in inflammation in response to P. gingivalis, it i unknown how intracellular host defense mechanisms to this pathogen contribute to persistent infection and resulting in chronic inflammation. We have recently reported on a novel strategy by which P. gingivalis modulates the levels of key intracellular proteins involved in cell death and host defense responses. We demonstrate that the lysine-specific bacterial cysteine protease of P. gingivalis (gingipain K - Kgp) induces the proteolysis of receptor interacting protein kinase 1 (RIPK1) and RIPK2. Our preliminary studies reveal functional consequences of P. gingivalis mediated RIPK degradation on intracellular immune signaling responses. These studies support the emerging concept that pathogen-mediated chronic inflammatory disorders result from specific pathogen-mediated evasion strategies resulting in low-grade chronic inflammation. Given the roles of RIPK in TNF-R induced cell activation and sensing of intracellular pathogens, we propose the ability of P. gingivalis to transiently degrade RIPK functions as a mechanism to avoid intracellular innate immune signaling and allows for bacterial persistence within target cells. The following specific Aims will test this hypothesis: Aim 1. To define the functional consequences of Kgp-mediated RIPK degradation on innate immune signaling and bacterial persistence; Aim 2. To characterize the ability of RIPK cleaved products to function in inhibition of NF?B activation; Aim 3. To assess the efficiency of gingipain inhibitos on the inhibition of P. gingivalis-induced chronic inflammation at local sites in a murine model; and Aim 4. To assess the efficiency of gingipain inhibitors on the inhibition of P. gingivalis-induced chronic inflammation at systemic sites in an ApoE-/- murine model. The ability to specifically block Kgp-mediated modification of cellular kinases represents a novel strategy to target bacterial persistence and innate immune signaling within host cells. Successful undertaking of the proposed studies has the potential to identify and validate novel therapeutic interventions that target pathogen evasion mechanisms associated with chronic infection and the resulting inflammatory sequelae.