This renewal application proposes to continue to test novel hypotheses about lipid mediators in corneal inflammation and remodeling after injury. It addresses the critical balance between signaling mechanisms that promote cellular damage and repair, which is fundamental for the maintenance of corneal integrity and function. The hypothesis is that while platelet-activating factor (PAF) plays a key role during excessive corneal inflammation (e.g., chemical burns) and contributes to tissue destruction and neovascularization, the12-1ipoxygenase (12-LOX) derivative, 12-(S)-hydroxyeicosatetraenoic acid (12-[S]-HETE), contributes to repair of the cornea. We propose to test four specific hypotheses: that during sustained inflammation, PAF induces impaired wound healing by (a) activation of specific transcription factors in the promoter of MMP-9 and (b) modulating apoptotic signals through the expression or silencing of PAF-R in stromal cells and that PAF increases corneal neovascularization by activating VEGF signals and MMP-2 through induction of the membrane type-1 MMP (MT1-MMP). Also, 12-(S)-HETE acts as a second messenger to promote repair and wound healing through (c) MAPK-mediated pathways and expression of cell-cycle regulatory proteins, and (d) increased induction of its enzyme, 12-LOX, that allows the transcellular synthesis of lipoxins. These compounds are suppressors of inflammation. Selective PAF-R antagonists and 12-LOX inhibitors as well as PAF-R knockout mice will be used to determine the site of action. The debridement of corneal epithelium will be employed as a model of wound healing and the corneal mouse micropocket as an in vivo model of neovascularization. Studies on activation of regions of the MMP-9 promoter will be done in transiently transfected cells. To determine the activation of transcription factors, EMSA and supershift assays will be used. Quantification of specific mRNA will be accomplished by real-time PCR. Identification of pathway components will be done by RP-HPLC, Western blot, ELISA, and immunochemistry. The results obtained will define the involvement of PAF and 12-(S)-HETE in corneal damage and repair and could lead to the development of drugs that target selective steps in the corneal inflammatory response.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY004928-23
Application #
6910620
Study Section
Special Emphasis Panel (ZRG1-VISA (01))
Program Officer
Shen, Grace L
Project Start
1983-07-01
Project End
2008-06-30
Budget Start
2005-07-01
Budget End
2006-06-30
Support Year
23
Fiscal Year
2005
Total Cost
$284,000
Indirect Cost
Name
Louisiana State University Hsc New Orleans
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
782627814
City
New Orleans
State
LA
Country
United States
Zip Code
70112
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He, Jiucheng; Kakazu, Azucena H; Bazan, Nicolas G et al. (2011) Aspirin-triggered lipoxin A4 (15-epi-LXA4) increases the endothelial viability of human corneas storage in Optisol-GS. J Ocul Pharmacol Ther 27:235-41
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Kenchegowda, Sachidananda; Bazan, Nicolas G; Bazan, Haydee E P (2011) EGF stimulates lipoxin A4 synthesis and modulates repair in corneal epithelial cells through ERK and p38 activation. Invest Ophthalmol Vis Sci 52:2240-9
Li, Na; He, Jiucheng; Schwartz, Carl Eric et al. (2010) Resolvin E1 improves tear production and decreases inflammation in a dry eye mouse model. J Ocul Pharmacol Ther 26:431-9
Kenchegowda, Sachidananda; Bazan, Haydee E P (2010) Significance of lipid mediators in corneal injury and repair. J Lipid Res 51:879-91
Cortina, M Soledad; He, Jiucheng; Li, Na et al. (2010) Neuroprotectin D1 synthesis and corneal nerve regeneration after experimental surgery and treatment with PEDF plus DHA. Invest Ophthalmol Vis Sci 51:804-10
Esquenazi, Salomon; He, Jiucheng; Li, Na et al. (2010) Immunofluorescence of rabbit corneas after collagen cross-linking treatment with riboflavin and ultraviolet A. Cornea 29:412-7
Esquenazi, Salomon; Bazan, Haydee E P (2010) Role of platelet-activating factor in cell death signaling in the cornea: A review. Mol Neurobiol 42:32-8
He, Jiucheng; Eastlack, Jason P; Bazan, Haydee E P (2010) The induction of an angiogenic response in corneal myofibroblasts by platelet-activating factor (PAF). Curr Eye Res 35:1063-71

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