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Holly Rose Chinnery; Alterations in tight junction expression and endothelial cell density during a mouse model of sterile corneal inflammation.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3094.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously reported that application of toll-like receptor (TLR) ligands onto the injured corneal surface of C57BL/6 mice induces corneal edema at 24 hours post-treatment which subsides by one week. We tested the hypotheses that endothelial expression of the tight junction protein, zonula occludens-1 (ZO-1), would be altered during experimental sterile corneal inflammation and that the endothelial cell density (ECD) would remain unaffected.<br />
C57BL/6J mice aged 6-10 weeks were anaesthetized and received central 1mm corneal abrasions with an Alger Brush followed by topical application of saline or CpG-ODN (TLR9 agonist). At 24 hours and one week post-treatment, eyes were enucleated and fixed in paraformaldehyde and processed for immunofluorescence staining of ZO-1. Confocal imaging of corneal flat mounts were analysed for expression of endothelial ZO-1 (mean pixel intensity) and the density of corneal endothelial cells was evaluated by masked observers. Differences between groups were determined using ANOVA.
Compared to untreated corneas, the expression of ZO-1 by the corneal endothelium was unchanged in saline-treated corneas at both 24 hours and 1 week. Treatment with CpG-ODN led to a significant reduction in the expression of ZO-1 by the corneal endothelium at 24 hours, which returned to normal levels by 1 week. Endothelial cell density was similar to untreated corneas at 24h but was significantly reduced in CpG-ODN treated corneas at 1 week (2009 ± 46 [mean ± S.E.M] cells/mm2) compared to untreated eyes (2426 ± 102 cells/mm2). There was no difference in the ECD between CpG-ODN treated eyes and saline treated eyes at one week.
Experimental sterile corneal inflammation was associated with a transient reduction in ZO-1 expression by the corneal endothelium. The loss of corneal endothelial cells at later stages of inflammation suggest that sterile insults to the cornea may be associated with a preceding down-regulation of tight junction proteins. <br />
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