Abstract
Purpose :
Dry eye is a frequent and serious complication of graft versus host disease (GVHD). Levels of a variety of proinflammatory cytokines are significantly elevated in tears of GVHD patients. Mucins are glycosylated proteins that are crucial for ocular surface hydration. Thus, a decrease in mucins expression can have a significant negative impact on tear film. The present study investigates the effect of proinflammatory cytokines TNFα and IL-6 on expression of ocular mucins.
Methods :
Human conjunctival and corneal epithelial cells were used. Conjunctival cells were grown in serum-free low calcium F12/DMEM medium, and then switched to serum-containing keratinocyte medium for stratification. Corneal epithelial cells were grown on transwell membrane inserts, in growth factor-supplemented complete keratinocyte medium. The cells were exposed to different doses of TNFα and IL-6 for 24 hours. The cells were harvested for mRNA isolation and preparation of protein lysates. The mucins 1, 4, 5AC, 16 &19 gene expression and protein quantification was done using real time PCR and ELISA respectively. Statistical analysis was performed by one-way ANOVA and tuckey’s test.
Results :
Both TNFα and IL-6 caused a decrease in the gene and protein expression of mucins in corneal and conjunctival cells. The decrease was dose dependent. The doses that recapitulated the published values of tear levels in the GVHD patients caused the most significant decrease. Our results tentatively suggest that elevated levels of proinflammatory cytokines may contribute to the pathogenesis of dry eye by decreasing the expression of ocular mucins in GVHD.
Conclusions :
Based on our results it may be concluded that proinflammatory cytokines such as TNFα and IL-6 decrease the expression of mucins in the corneal and conjunctival epithelial cells. Since the levels of these cytokines are significantly elevated in the tear fluid of GVHD patients, cytokine-mediated decrease in mucins can significantly contribute to the pathogenesis of GVHD associated dry eye.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.