Departments of Ophthalmology and Anatomy & Cell Biology, Kresge Eye Institute, Wayne State University School of Medicine, 4717 St. Antoine, Detroit, MI 48201, USA.
Microbes Infect. 2010 Nov;12(12-13):978-89. doi: 10.1016/j.micinf.2010.06.007. Epub 2010 Jul 1.
Among bacterial pathogens, Pseudomonas (P.) aeruginosa infection is the most sight threatening. The corneal innate immune responses are key mediators of the host's defense to P. aeruginosa. Using a mouse model of Pseudomonas keratitis, we evaluated the protective effects of topical application of flagellin, a ligand for Toll-Like receptor 5 (TLR5), on the development of Pseudomonas keratitis and elucidated the underlying mechanisms. Topical application of purified flagellin 6 and 24 h prior to P. aeruginosa inoculation on injured mouse corneas significantly attenuated clinical symptoms of P. aeruginosa keratitis, decreased bacterial burden, and suppressed infection induced inflammation in the B6 mouse cornea. Topical application of flagellin on wounded cornea induced PMN infiltration and markedly upregulated cathelicidin-related antimicrobial peptide (CRAMP) expression. In PMN depleted mice, flagellin promoted bacterial clearance in the cornea compared to that of the PBS treated mice, but was unable to prevent corneal perforation and systemic bacterial dissemination and sepses. Deletion of CRAMP increased corneal susceptibility to P. aeruginosa and abolished flagellin-induced protection in B6 mice. Our findings illustrate the profound protective effect of flagellin on the cornea innate defense, a response that can be exploited for prophylactic purposes to prevent contact lens associated Pseudomonas keratitis.
在细菌性病原体中，铜绿假单胞菌（P. aeruginosa）感染是最具威胁视力的感染。角膜固有免疫反应是宿主防御铜绿假单胞菌感染的关键介质。本研究采用铜绿假单胞菌角膜炎的小鼠模型，评估了 flagellin（Toll 样受体 5（TLR5）的配体）局部应用对铜绿假单胞菌角膜炎发展的保护作用，并阐明了潜在的机制。在受伤的小鼠角膜上接种铜绿假单胞菌之前，6 小时和 24 小时局部应用纯化的 flagellin，可显著减轻铜绿假单胞菌角膜炎的临床症状，减少细菌负荷，并抑制 B6 小鼠角膜感染引起的炎症。flagellin 局部应用于受伤的角膜可诱导 PMN 浸润，并显著上调抗菌肽相关 Cathelicidin（CRAMP）的表达。在PMN 耗竭的小鼠中，与 PBS 处理的小鼠相比，flagellin 促进了角膜中的细菌清除，但不能预防角膜穿孔和全身性细菌播散和败血症。CRAMP 缺失增加了角膜对铜绿假单胞菌的易感性，并消除了 flagellin 在 B6 小鼠中诱导的保护作用。我们的研究结果表明，flagellin 对角膜固有防御具有深远的保护作用，这种反应可被用于预防接触镜相关铜绿假单胞菌角膜炎的预防性治疗。
