Abstract
Purpose :
Together, the corneal, limbal, and conjunctival epithelium form the mucosal surface of the eye. Of these, the corneal epithelium is responsible for the protection of the eye from invading pathogens and provides a smooth refractive surface that is essential for vision. Dry eye disease (DED) is a visually debilitating, painful condition that is associated with many systemic diseases. Desiccating stress plays a key role in the pathophysiology of DED. This study investigated mitochondrial and metabolic alterations that occur in DED using an established in vitro desiccating stress model.
Methods :
To induce desiccation, confluent telomerase-immortalized human corneal epithelial (hTCEpi) cells were exposed to air for 5 or 10 minutes at room temperature (25°C), then re-supplemented with a defined keratinocyte basal medium for 24 hours. Cell morphology and viability were assessed using phase-contrast microscopy and trypan blue, respectively. Expression of mitophagy-related proteins and inflammatory cytokines were analyzed using western blotting and enzyme-linked immunosorbent assay (ELISA). Cells cultured on coverslip bottom dishes were stained for reactive oxygen species and mitochondrial membrane potential and imaged using laser scanning confocal microscopy. The metabolic phenotype was evaluated using a Seahorse XF cell mito stress test.
Results :
Cell-membrane vacuolization was observed in hTCEpi cells exposed to desiccating stress and viability was decreased from 98% to 72%. After ten minutes, there was a measurable increase in IL-8. Expression of mitophagy-related proteins was altered. There was an increase in cleavage of the protein kinase PINK1, resulting in the accumulation of the 55kD isoform.
Conclusions :
Taken together, these data suggest that dessicating stress induces PINK1-mediated mitophagy in corneal epithelial cells. Further studies are needed to fully elucidate the changes in mitochondrial and metabolic homeostasis that occur in DED.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.