Microbial keratitis is a common cause of vision loss. The cornea is exquisitely sensitive to inflammation- mediated damage and therefore has strong innate defenses. However, when the epithelial barrier function is breached, opportunistic bacterial and fungal pathogens can gain access to the epithelial cell layers and colonize in the cornea, leading to infection. During the initial grant period, flagellin, the ligand of Toll-like receptor 5 (TLR5), was used to fortify corneal innate immunity and render resistance to a broad spectrum of keratitis causing pathogens, including Pseudomonas aeruginosa, Candida albicans and Aspergillus fumigates. This highly inducible and robust innate mucosal protection can be attributed to flagellin-induced genomic reprogramming in the epithelium which, in turn, interacts with professional immune cells to control inflammation and to eradicate invading pathogens. The hypothesis in this application is that flagellin, through TLR5, stimulates protective corneal innate mucosal immunity that involves epithelial cells, infiltrated PMNs, and activated dendritic cells, collectively conferring robust resistance to microbial keratitis.
Three specific aims are proposed to test this hypothesis: 1) To determine how flagellin-induced reprogramming is regulated in corneal epithelial cells and in the cornea. This can be assessed by using the chromatin immunoprecipitation assay and histone deacetylase inhibitors for gene-specific chromatin modification and by using siRNA and knockout mice for delineating the role of activating transcription factor-3, a transcription factor induced by fg, in regulating the innate immune response in the cornea. 2) To determine how the epithelium participates in and coordinates flagellin-induced mucosal innate immune defense against microbial keratitis. The role of the epithelium and its interaction with dendritic cells in innate defense will be determined by using various transgenic and knockout mice, bone marrow reconstitution, and cell depletion. 3) To determine how flagellin induces protection against non-flagellated pathogens in the cornea. The therapeutic potential of flagellin and its mechanisms of action will be characterized by using mouse models of fungal keratitis (Candida and Aspergillus as pathogens and post-infection topical flagellin application) and double TLR knockout mice. The results of the proposed study should shed light on corneal innate immunity and its induction, and may lead to the development of new prophylactic/therapeutic modalities for preventing and treating microbial keratitis.

Public Health Relevance

This proposal is to determine the mechanisms underlying flagellin-induced protective corneal mucosal immunity and to explore its therapeutic potential to treat microbial keratitis, a common cause of vision loss. The knowledge gained will be critical for the long-term goal of developing mechanism-based, efficacious prophylactic/therapeutic modalities for preventing and treating infectious keratitis.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
2R01EY017960-04A1
Application #
8248480
Study Section
Special Emphasis Panel (ZRG1-BDCN-H (02))
Program Officer
Mckie, George Ann
Project Start
2006-12-01
Project End
2016-04-30
Budget Start
2012-05-01
Budget End
2013-04-30
Support Year
4
Fiscal Year
2012
Total Cost
$380,000
Indirect Cost
$130,000
Name
Wayne State University
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
001962224
City
Detroit
State
MI
Country
United States
Zip Code
48202
Cui, Xinhan; Gao, Nan; Me, Rao et al. (2018) TSLP Protects Corneas From Pseudomonas aeruginosa Infection by Regulating Dendritic Cells and IL-23-IL-17 Pathway. Invest Ophthalmol Vis Sci 59:4228-4237
Sun, Haijing; Lee, Patrick; Yan, Chenxi et al. (2018) Inhibition of Soluble Epoxide Hydrolase 2 Ameliorates Diabetic Keratopathy and Impaired Wound Healing in Mouse Corneas. Diabetes 67:1162-1172
Gao, Nan; Me, Rao; Dai, Chenyang et al. (2018) Opposing Effects of IL-1Ra and IL-36Ra on Innate Immune Response to Pseudomonas aeruginosa Infection in C57BL/6 Mouse Corneas. J Immunol 201:688-699
Singh, Pawan Kumar; Guest, John-Michael; Kanwar, Mamta et al. (2017) Zika virus infects cells lining the blood-retinal barrier and causes chorioretinal atrophy in mouse eyes. JCI Insight 2:e92340
Ross, Bing X; Gao, Nan; Cui, Xinhan et al. (2017) IL-24 Promotes Pseudomonas aeruginosa Keratitis in C57BL/6 Mouse Corneas. J Immunol 198:3536-3547
Dong, Chen; Gao, Nan; Ross, Bing X et al. (2017) ISG15 in Host Defense Against Candida albicans Infection in a Mouse Model of Fungal Keratitis. Invest Ophthalmol Vis Sci 58:2948-2958
Gao, Nan; Liu, Xiaowei; Wu, Jiayin et al. (2017) CXCL10 suppression of hem- and lymph-angiogenesis in inflamed corneas through MMP13. Angiogenesis 20:505-518
Zhang, Xilin; Liu, Queping; Wang, Jie et al. (2016) TIM-4 is differentially expressed in the distinct subsets of dendritic cells in skin and skin-draining lymph nodes and controls skin Langerhans cell homeostasis. Oncotarget 7:37498-37512
Yan, Chenxi; Gao, Nan; Sun, Haijing et al. (2016) Targeting Imbalance between IL-1? and IL-1 Receptor Antagonist Ameliorates Delayed Epithelium Wound Healing in Diabetic Mouse Corneas. Am J Pathol 186:1466-80
Gao, Nan; Yan, Chenxi; Lee, Patrick et al. (2016) Dendritic cell dysfunction and diabetic sensory neuropathy in the cornea. J Clin Invest 126:1998-2011

Showing the most recent 10 out of 43 publications