Abstract
Purpose :
The purpose of this study is to determine if primary ocular herpes simplex virus -1 (HSV-1) infection causes the development of hypoxia in corneal tissue of infected eyes, and the relative contribution of hypoxia in development of herpes stromal keratitis in a mouse model.
Methods :
C57BL/6 mice received intravenous (tail-vein) injection of pimonidazole drug at different time points post ocular HSV-1 infection or scratching. Pimonidazole (hypoxia marker) staining was done to identify the hypoxic areas in frozen sections of the corneas using confocal imaging. In addition, carbonic anhydrase IX (a metabolic marker of hypoxic tissue) and HIF (transcription factor for hypoxia) staining in frozen sections were determined with confocal microscopy. Corneal lactate levels were detected by colorimetric lactate assay in infected and scratch control groups. Phenol red thread test was used to measure the volume of tears in both groups of mice. Slit lamp and stereomicroscopy imaging were performed to determine the correlation between the corneal epithelial defects and development of hypoxia, and the outcome of hypoxia on corneal angiogenesis.
Results :
Our results showed pockets of pimonidazole staining in the corneal epithelium of infected, but not scratch control eyes on day 8 and day 10 post-infection. Similarly, carbonic anhydrase IX and HIF staining in infected corneas suggested the development of hypoxia. Corneal lactate levels were also significantly higher in infected than scratch control groups of mice during the onset of clinical disease period. Cornea gets its oxygen supply through the tear film overlying the ocular surface. The phenol red thread test showed significantly reduced volume of tears in infected than scratch control eyes on day 7 and 10 post-infection. A positive correlation between corneal epithelial defects and the development of corneal hypoxia was determined in HSV-1 infected eyes. In addition, the extent of corneal angiogenesis directly correlated with hypoxic area in the corneal epithelium of infected eyes during the onset of clinical disease.
Conclusions :
Together, our results show the development of hypoxia in the corneal epithelium of HSV-1 infected eyes, and the correlation of hypoxia with corneal angiogenesis in infected eyes in a mouse model. The studies are being carried out to ascertain if alleviating corneal hypoxia reduces the severity of HSK.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.