P. gingivalis Mediated Evasion Strategies

描述(由申请人提供)：一些成功的病原体已经进化出逃避宿主防御的机制，从而建立了持续性和慢性感染。口腔病原体牙龈卟啉单胞菌慢性感染的一个特征是诱导慢性炎症反应。尽管膜结合的先天免疫受体，包括Toll样受体(TLR)，在牙龈假单胞菌的炎症反应中发挥了作用，但尚不清楚细胞内对这种病原体的防御机制如何促进持续感染并导致慢性炎症。我们最近报道了一种新的策略，通过该策略，牙龈假单胞菌可以调节参与细胞死亡和宿主防御反应的关键细胞内蛋白的水平。我们证明了牙龈假单胞菌赖氨酸特异的细菌半胱氨酸蛋白酶(牙周蛋白K-KGP)可以诱导受体相互作用蛋白激酶1(RIPK1)和RIPK2的蛋白分解。我们的初步研究揭示了牙龈假单胞菌介导的RIPK降解对细胞内免疫信号反应的功能影响。这些研究支持一个新兴的概念，即病原体介导的慢性炎症性疾病是由特定的病原体介导的逃避策略引起的，从而导致低级别的慢性炎症。鉴于RIPK在肿瘤坏死因子受体诱导的细胞激活和细胞内病原体感知中的作用，我们提出牙龈假单胞菌能够瞬时降解RIPK功能，作为一种避免细胞内天然免疫信号的机制，并允许细菌在靶细胞内持续存在。以下特定目的将验证这一假说：目的1.确定KGP介导的RIPK降解对天然免疫信号和细菌持久性的功能后果；目的2.表征RIPK裂解产物在抑制核因子B激活方面的功能；目的3.在小鼠模型中评估牙龈痛抑制剂对牙龈假单胞菌诱导的局部慢性炎症的抑制效率；以及目的4.在载脂蛋白E/小鼠模型中评价牙龈痛抑制剂对牙龈假单胞菌诱导的全身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一种针对细菌持久性和宿主细胞内天然免疫信号的新策略。拟议研究的成功开展有可能确定和验证针对与慢性感染和由此产生的炎性后遗症相关的病原体逃避机制的新的治疗干预措施。

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.