Human Corneal Epithelial Cells Synthesize ELR⁻α-Chemokines in Response to Proinflammatory Mediators

Abstract

The purpose of this study was to characterize the synthesis of α -chemokines IP-10, MIG, and I-TAC by human corneal epithelial cells (HCE) following exposure to proinflammatory mediators. Supernatants were collected from HCE cultures stimulated with individual or combinations of TNF-α, IL-1α, and IFN-γ, and assayed for α -chemokines by ELISA. RT-PCR was used to detect IFN-γ receptor mRNA. Activation of STAT1 was determined by Western blotting. Stimulation of HCE with either IL-1α or TNF-α increased IP-10 protein synthesis up to 6-fold, whereas insignificant levels of MIG and I-TAC were induced. The epithelial cells were found to express IFN-γ receptors constitutively. Exposure to the ligand resulted in STAT1 phosphorylation and production of nanogram amounts of IP-10, I-TAC, and MIG. When HCE were stimulated with combinations of TNF-α and IFN-γ, or IL-1α and IFN-γ, the levels of IP-10 and I-TAC secreted were > 150-fold higher than that produced following exposure to a single cytokine. In contrast, MIG protein synthesis was not enhanced upon stimulation with cytokine combinations. The abundant production of ELR⁻α -chemokines following appropriate stimulation suggests that HCE may play an important role in the recruitment of effector cells such as activated T-lymphocytes to inflamed corneal tissue. The data also indicate that the synthesis of IP-10, I-TAC, and MIG are differentially regulated in HCE.

KEYWORDS:

• Alpha-chemokines
• corneal epithelial cells