Abstract
Purpose :
Hyperosmotic stress, a key component of dry eye disease, triggers endoplasmic reticulum stress (ERS) and ERS-induced apoptosis. Here, we investigated the effect of tauroursodeoxycholic acid (TUDCA), a chemical chaperone which facilitates protein folding and reduces ERS, on human corneal epithelial cells exposed to hyperosmotic conditions.
Methods :
Stratified cultures of telomerase-immortalized human corneal epithelial cells were exposed to increasing concentrations of sodium chloride with or without TUDCA. The expression levels of the ERS markers sXBP1, CHOP and BiP were determined using quantitative real-time PCR. Viability was assessed using a tetrazolium compound (MTS) and crystal violet (CV). The expression of genes mediating the inflammatory response was assessed by PCR array. Data are reported as the median ratio ± standard deviation between treated and control cells.
Results :
Exposure to hyperosmotic conditions significantly stimulated the transcription of ERS-related genes and had a concomitant cytotoxic effect (MTS= 31±6%; CV staining= 71±19%). Addition of TUDCA to the media significantly improved cell survival (MTS= 86±3% p<0.001; CV staining= 92±7% p<0.001) and mitigated the inflammatory signals known to be induced under hyperosmotic stress. We found that IL10RB, a subunit of the IL10 receptor involved in blocking the pro-inflammatory NF-κB pathway, was significantly up-regulated following addition of TUDCA. A neutrophil chemoattractant, CXCL8 and IL5, both elevated in dry eye disease, were significantly down-regulated.
Conclusions :
Alleviation of the endoplasmic reticulum stress promotes corneal epithelial cell survival and reduces inflammatory signals associated with hyperosmotic stress. This strategy could be tested therapeutically for the treatment of dry eye disease.
Fundings:
Supported by the National Institutes of Health, NEI Grant R01EY026147 (P.A.), The Franco-American Fulbright Commission, Arthur Sachs – Harvard University, Philippe Foundation and la Fondation des Aveugles de Guerre (D.G.).
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.