Abstract
Purpose :
To evaluate if corneal collagen cross-linking (CXL) pretreatment dampens subsequent suture emplacement reactivation of inflammation and hemangiogenesis as well as lymphangiogenesis in rats.
Methods :
The TUNEL assay evaluated the effects of CXL treatment on keratocyte apoptosis on days 3, 7, 14 and 28. CD45, CD68 and MMP-9 immunofluorescent staining determined immune cell activation and stromal leucocyte and macrophage infiltration. Real-time qPCR measured proinflammatory cytokine gene expression levels. Morphometric measurements evaluated hemangiogenesis and lymphangiogenesis. Real-time qPCR determined angiogenic and lymphangiogenic gene expression levels. Western blotting analyzed vascular endothelial cell CD31 and lymphatic vessel endothelial hyaluronan receptor (LYVE-1) protein expression levels.
Results :
CXL treatment initially induced stromal infiltration of CD45, CD68 and MMP-9 immunostained cells which led to inflammation between days 3 to 14. The IFN-γ, MMP-9 and MCP-1 mRNA expression levels also increased along with rises in keratocyte apoptosis. By day 28, all of these effects had waned to levels similar to those in the normal control (NC) corneas. Suture emplacement subsequently vascularized both CXL-pretreated (CXL+SNV) and NC groups. On days 7 and 14 following this procedure, the declines in angiogenesis and lymphangiogenesis and CD45+ and CD68+ cell infiltration in the CXL-pretreated corneas exceeded those in the NC group. Angiogenic and lymphangiogenic mRNA expression levels and CD31 and LYVE-1 protein expression levels along with proinflammatory cytokine levels also progressively decreased more in the CXL-pretreated group during this period.
Conclusions :
The magnitudes of rises in suture emplacement-induced proinflammatory mediators and associated hem and lymphangiogenesis responses were less in CXL pretreated corneas than in their NC counterpart. This difference suggests that future studies are warranted to determine if CXL pretreatment has the potential to decrease corneal immune responses and thereby provide more effective treatment of hemantic- and lymphatic-related corneal diseases.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.