Oxidative killing of Pneumococcus

肺炎链球菌(Spn)是社区获得性肺炎和 儿童和老年人的脑膜炎，艾滋病毒患者的败血症。提升主机的功能 免疫反应可以提供针对Spn的新的干预策略。我们有一个严重的差距 识别新的、广泛的、抗Spn的呼吸系统先天免疫系统机制的知识。 支气管上皮细胞(BEC)是Spn感染的主要应答细胞。BEC协调 存在于由蛋白质组成的呼吸道表面液体中的氧化胞外抗菌系统 乳过氧化物酶(LPO)、硫氰酸根阴离子(SCN-)和过氧化氢(H2O2)。LPO氧化SCN- 利用过氧化氢对次硫氰酸盐(OSCN-)进行杀菌。NADPH酶--双氧化酶1(Duox1) 在内皮细胞顶膜高表达的蛋白质是过氧化氢抗菌作用的来源。 LPO的。我们的初步结果表明，基于Duox1/LPO的系统有效地杀死了几个菌株 不同实验体系中的SPN。我们的长期目标是确定Duox1/LPO/SCN- 在人类的Spn感染中，抗菌系统可以被操纵用于治疗目的。这个 本研究的目的是建立基于Duox1/LPO的氧化机制的抗Spn作用。 根据初步数据，我们的中心假设是Duox1/H_2O_2/LPO/SCN-系统杀死Spn 细菌以不依赖菌株的方式减轻小鼠的感染和相关的组织损伤 Spn肺部感染模型。为了检验这一假设，我们的具体目标是确定机制 Duox1/LPO对Spn的体外杀伤作用，探讨Duox1在体内对Spn的杀伤作用 基于Duox1/LPO系统的治疗操作是否能减轻Spn肺炎 动物模型。提出这项研究的理由是，我们需要刻画出 基于Duox1/LPO的系统正在与Spn对抗，以探索其未来在人类中的治疗潜力。 预计我们的目标将产生以下预期结果：1)确定 基于Duox1/LPO的抗Spn系统的抗菌机制2)体内实验研究 Duox1与Spn感染的相关性；以及3)提供关于Duox1治疗潜力的基本结果 基于Duox1/LPO的抗Spn肺部感染机制我们的创新工作表明，一种独特的 抗菌系统对Spn具有强大的杀灭作用，并探索了一种新的、非传统的免疫机制 因为它有可能被用来对抗一种主要的肺部病原体。总而言之，我们的建议将产生积极的影响 在呼吸道上皮和Spn生物学领域的影响，以及一般抗菌天然免疫 识别Duox1和LPO作为呼吸道的一种新的、至关重要的先天免疫武器的反应 针对Spn的天然免疫系统。

Streptococcus pneumoniae (Spn) is the main cause of community acquired pneumonia and meningitis in children and the elderly, and of septicemia in HIV patients. Boosting the function of host immune responses could offer novel intervention strategies against Spn. There is a critical gap in our knowledge to identify new, broad range, anti-Spn mechanisms of the respiratory innate immune system. Bronchial epithelial cells (BEC) are the primary responders to Spn infection. BECs orchestrate an oxidative extracellular antimicrobial system present in the airway surface liquid consisting of the protein lactoperoxidase (LPO), the thiocyanate anion (SCN-) and hydrogen peroxide (H2O2). LPO oxidizes SCN- using H2O2 into microbicidal hypothiocyanite (OSCN-). Dual oxidase 1 (Duox1), an NADPH oxidase protein highly expressed in the apical membrane of BECs, is the H2O2 source for the antimicrobial action of LPO. Our preliminary result show that the Duox1/LPO-based system efficiently kills several strains of Spn in different experimental systems. Our long-term goal is to determine whether the Duox1/LPO/SCN- antibacterial system could be manipulated in Spn infection for therapeutic purposes in humans. The objective of this proposal is to establish the anti-Spn role of the Duox1/LPO-based oxidative mechanism. Based on preliminary data our central hypothesis is that the Duox1/H2O2/LPO/SCN- system kills Spn bacteria in a strain-independent manner, attenuates infection and associated tissue damage in a mouse model of Spn lung infection. To test this hypothesis, our specific aims are to determine the mechanism of Spn killing by Duox1/LPO in vitro, to establish the in vivo role of Duox1 in Spn killing, and to explore whether therapeutic manipulation of the Duox1/LPO-based system attenuates Spn pneumonia in an animal model. The rationale for the proposed research is that we need to characterize how powerful the Duox1/LPO-based system is in fighting Spn to explore its therapeutical potential in humans in the future. It is anticipated that our aims will yield the following expected outcomes: 1) identification of the antibacterial mechanism of the Duox1/LPO-based system against Spn, 2) establishing the in vivo relevance of Duox1 in Spn infection; and 3) providing essential results on the therapeutic potential of the Duox1/LPO-based mechanism to attenuate Spn lung infection. Our innovative work shows that a unique antimicrobial system is powerful in killing Spn and explores a novel, nontraditional immune mechanism for its potential to be used against a major lung pathogen. In summary, our proposal will have a positive impact in the fields of airway epithelial and Spn biology, and general antibacterial innate immune responses by identifying Duox1 and LPO, as a novel, crucial, innate immune weapons of the respiratory innate immune system against Spn.