P. aeruginosa type III secreted effectors in corneal disease

铜绿假单胞菌感染是与长期佩戴有关的角膜疾病的常见原因 隐形眼镜在美国使用。铜绿假单胞菌用来促进疾病的主要毒力因素之一是 它的III型分泌系统，一个分子注射器，允许细菌直接注入效应蛋白 进入目标宿主细胞。III型分泌物在角膜疾病中的作用尚未得到广泛研究，但 最初的报告表明，角膜疾病取决于由表达的效应物的补充 感染细菌。表达高效磷脂酶ExoU的“细胞毒”菌株广泛依赖于III型 分泌物促进疾病，而产生EXOS的“侵袭性”菌株似乎不依赖于III型 分泌物才能引发角膜疾病。 我们回顾了III型分泌物在EXOS+诱发的角膜疾病发病机制中的作用。 具有侵袭性的铜绿假单胞菌分离株。我们的初步数据显示角膜疾病严重依赖于 III型分泌物，特别是两个效应器EXOS和ExoT。此外，我们还提供证据表明 III型分泌物在角膜疾病中的主要作用是通过渗透中性粒细胞来延缓杀戮。 因此，这项建议的重点是确定EXOS的单个酶活性的作用 和ExoT在体内阻止中性粒细胞清除。我们将把这些发现与实验联系起来。 目的探讨EXOS和ExoT在防止分离的原代中性粒细胞吞噬杀伤中的作用。 我们还将研究ExoU表达的“细胞毒性”和EXOS-2在发病机制上的差异。 表达侵袭性的铜绿假单胞菌菌株，以确定是否有任何差异可以直接与 这两个效应器的活动。 了解效应蛋白在角膜疾病中的作用是制定 防治眼部铜绿假单胞菌感染的新策略。

P. aeruginosa infections are a common cause of corneal disease associated with extended-wear contact lens use here in the US. One of the primary virulence factors P. aeruginosa uses to promote disease is its type III secretion system, a molecular syringe that allows the bacterium to directly inject effector proteins into targeted host cells. The role of type III secretion in corneal disease has not been studied extensively, but initial reports suggest that corneal disease depends on the complement of effectors being expressed by the infecting bacteria. "Cytotoxic" strains expressing the potent phospholipase ExoU rely extensively on type III secretion to promote disease, whereas ExoS-producing "invasive" strains, appear to not rely on type III secretion in order to elicit corneal disease. We have revisited the role of type III secretion in the pathogenesis of corneal disease elicited by ExoS+ "invasive" isolates of P. aeruginosa. Our preliminary data demonstrates that corneal disease relies critically on type III secretion and on the two effectors ExoS and ExoT, in particular. In addition, we provide evidence that the primary role of type III secretion in corneal disease is to stave off killing by infiltrating neutrophils. Accordingly, the focus of this proposal is to determine the role of the individual enzymatic activities of ExoS and ExoT in preventing clearance by neutrophils in vivo. We will correlate these findings with experiments aimed at examining the role of ExoS and ExoT in preventing phagocytic killing by isolated primary neutrophils. We will also examine the difference in pathogenesis between ExoU-expressing "cytotoxic" and ExoS- expressing "invasive" strains of P. aeruginosa in order to determine if any differences can be directly linked to the activities of these two effectors. Understanding the role of effector proteins in corneal disease is an important step towards formulating new strategies for preventing and treating P. aeruginosa infections of the eye.