P. aeruginosa type III secreted effectors in corneal disease

 描述（由申请人提供）：铜绿假单胞菌是美国和全球微生物性角膜炎的最常见原因之一。铜绿假单胞菌使用分子注射器，称为III型分泌系统，以避免通过浸润中性粒细胞杀死，从而防止感染的清除。铜绿假单胞菌分离株可以分为两类，基于这些菌株使用其III型分泌系统注射的效应蛋白。"细胞毒性"分离株产生ExoU和ExoT，而"侵入性"分离株产生ExoS和ExoT。我们最近发现，铜绿假单胞菌的侵袭性分离株使用ExoS和ExoT来抑制中性粒细胞的两种主要杀菌功能，即活性氧产生和抗菌颗粒与含细菌吞噬体的融合。因此，拟议的研究计划将检查中性粒细胞中ExoS和ExoT抑制的分子途径，以阻断活性氧产生（Aim 1）和颗粒融合（Aim 2）。我们还将确定向中性粒细胞注射ExoS和ExoT是否可以通过诱导细胞凋亡或效应子介导的吞噬抑制来灭活中性粒细胞，从而在群体水平上促进角膜感染。在这里，第一个被吞噬的细菌将充当毒丸，使中性粒细胞失活，从而使其他细菌茁壮成长（目标3）。因此，我们的研究计划准备发现被铜绿假单胞菌抑制的多种细胞过程，并发现治疗干预感染的新方法。

 DESCRIPTION (provided by applicant): P. aeruginosa is one of the most common causes of microbial keratitis, both in the U.S. and worldwide. P. aeruginosa uses a molecular syringe, called type III secretion system, to avoid killing by infiltrating neutrophils, thereby preventing clearance of the infection. P. aeruginosa isolates can be divided into two categories, based on the effector proteins these strains inject using their type III secretion system. "Cytotoxic" isolaes produce ExoU and ExoT, whereas "invasive" isolates produce ExoS and ExoT. We recently discovered that invasive isolates of P. aeruginosa use ExoS and ExoT to inhibit the two major bactericidal functions of neutrophils, reactive oxygen species production and fusion of antimicrobial granules with the bacteria-containing phagosome. Accordingly, the proposed program of research will examine the molecular pathways in neutrophils that ExoS and ExoT inhibit to block reactive oxygen species production (Aim 1) and granule fusion (Aim 2). We will also determine whether injection of ExoS- and ExoT into neutrophils can promote corneal infection on a population level, by inactivating neutrophils through induction of apoptosis, or effector-mediated inhibition of phagocytosis. Here the first phagocytosed bacterium would act as a poison pill, inactivating the neutrophil, thereby allowing the other bacteria to thrive (Aim 3). Our program of research is therefore poised to discover multiple cellular processes that are inhibited by P. aeruginosa, and uncover new approaches to therapeutically intervene in the infection.