Cytokine responses by conjunctival epithelial cells: An in vitro model of ocular inflammation

Objectives: We examined the differential secretion of cytokines by a conjunctival epithelial cell line in response to proinflammatory cytokines to identify the potential contributions during ocular surface inflammation. Methods: A conjunctival epithelial cell line was exposed to IFN-gamma, TNF-alpha, IL-4, or IL-13, and cytokine production was determined in supernatants at different times after exposure. Cell apoptosis was measured by flow cytometry. Results: TNF-alpha induced the greatest effect on cytokine secretion, which was time-dependent. TNF-alpha-stimulated secretion of IL-12p40 was significantly increased by 30min; GM-CSF, MCP-1, IL-6, IL-7, IL-8, and RANTES were significantly increased by 2 h, and IFN-gamma and IL-1 alpha by 24 h. After 48 h,TNF-alpha also induced a significant increase in IL-1 beta, IL-3, and IP-10 secretion. IFN-gamma significantly enhanced IP-10 and RANTES secretion after 48 h of exposure. Following IL-4 treatment there was a significant increase in eotaxin-1 after 24 h, and IL12p40 and IL-3 after 48 h. IL-13 significantly increased the secretion of eotaxin-1 after 24 h, and IL-8 after 48 h. Conclusion: Our results suggest that conjunctival epithelial cells are an important source of cytokines and chemokines that are regulated by proinflammatory cytokines and may play an important role in ocular surface inflammation. (C) 2008 Elsevier Ltd. All rights reserved.