Corneal and Conjunctival Fibroblasts Are Major Sources of Eosinophil-Recruiting Chemokines

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Background: Differential expression of chemokine genes were investigated in various types of ocular surface cells.
Methods: Primary cultures of human corneal epithelial cells (n = 3), corneal fibroblasts (n = 2), conjunctival epithelial cells (n = 2) and conjunctival fibroblasts (n = 2) were established and incubated with or without interleukin (IL)-4 (30ng/ml) and tumor necrosis factor (TNF)-α(30ng/ml) for 24 hours. Gene transcription levels of 33 chemokines and production of 4 chemokines were analyzed.
Results: After stimulation, chemokine expression increased for 18 of 33 coded chemokine gene transcripts. In stimulated conjunctival and corneal cells, CC chemokine genes increased in fibroblasts (expression of 6 out of 8 genes), while CXC chemokine genes increased in both epithelial cells (expression of 4 out of 9 genes in conjunctival epithelial cells and 7 out of 9 genes in corneal epithelial cells) and in fibroblasts (expression of 8 out of 9 genes in conjunctival and corneal fibroblasts). Except for MCP-1, gene transcription levels for most CC chemokines were inducible and, except for IP-10 and I-TAC, most CXC chemokines were constitutively expressed. Corneal epithelial cell and fibroblast production patterns for eotaxin-1, MCP-1 and IP-10 were comparable to the mRNA expression pattern.
Conclusions: Corneal and conjunctival fibroblasts exhibited marked increases in the expression of chemokines upon stimulation with TNF-α and IL-4, suggesting that fibroblasts may be one of the primary sources of chemokines in allergic conjunctival diseases. Therefore, regulation of chemokine production from these cells may be an effective strategy for treating such diseases.