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Sally S Twining, Debra Warejcka, Emily Andreae, Debbie Conklyn; Protease activated receptor 1 (PAR1) plays a role in corneal wound healing. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):738.
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© ARVO (1962-2015); The Authors (2016-present)
The protease activated receptor, PAR1, is known to regulate multiple functions in a cell but very little is known about PAR1 in the cornea with nothing known about the role of this protein in corneal stromal cells. The purpose of this study was to explore the role of PAR-1 in corneal wound healing and in corneal stromal fibroblasts and myofibroblasts.
An Alger brush was used to make two mm epithelial scrape wounds and a 21 ga needle was used to make full thickness wounds in PAR1 -/- and WT C57BL/6 mice. Wound areas (fluorescein) and opaque areas were measured over time. Wound and opaque areas were compared using One Way Repeated Measures Analysis of Variance and the Holm Sidak test for individual comparisons. Human donor corneal fibroblasts and TGFβ1 generated myofibroblasts were treated with PAR1 and PAR4 activating peptides and their respective scrambled peptides. Real time PCR and Western blot analysis were used to determine levels of mRNA and protein for Cyr61 and CXCL1.
Epithelial scrape wounds in PAR1 -/- mice (n=10) did not significantly close until after seven hours following wounding (3 hrs 93% ± 6.1, 7 hrs 104 ± 6.5) while the wounds in PAR1 +/+ mice (n=10) were significantly less at these time points with 38% closed by 3 hours (3 hrs 62.2% ± 6.5, 7 hrs 78.2 ± 5.5). Complete closure for the wounds occurred by 48 hrs for all of the PAR1 +/+ mice but only 60% of the corneal wounds were closed in the PAR1 -/- mice. For full thickness wounds the opaque area was significantly greater on days 4 and 5 for the PAR1 -/- mice (Day 4: 81.3 ± 5.5, Day 5: 53.3 ± 7.8) than the PAR1 +/+ mice Day 4: 54 ± 10, Day 5: 23.7 ± 7.2) with the greatest opacity in the PAR1 +/+ mice at 3 days and at 4 days in the PAR1 -/- mice. Human corneal stromal fibroblasts and myofibroblasts expressed both PAR1 and PAR4. Treatment of these cells with the PAR1 activating peptide significantly increased the cytokine, CXCL1 mRNA and the active matricellular protein Cyr61 mRNA and protein. There was no increase in these molecule with the PAR4 peptide or their scrambled peptides in the two cell types..
These results suggest that PAR1 is required for normal corneal wound healing and PAR1stimulation of expression of the cytokine CXCL1 and the active matricellular protein Cyr61 may play a role.
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