1 alpha,25-Dihydroxyvitamin D3 inhibits pro-inflammatory cytokine and chemokine expression in human corneal epithelial cells colonized with Pseudomonas aeruginosa.

The cytokines IL-1 beta, IL-6 and the chemokine IL-8 are key mediators of host inflammation. 1 alpha,25-Dihydroxyvitamin D3 (VD3) has been shown to regulate host immune responses in vivo and in vitro. The purpose of this study was to investigate whether the addition of VD3 to human corneal epithelial cells colonized with Pseudomonas aeruginosa altered the expression of IL-1 beta, IL-6 and IL-8. An immortalized human corneal epithelial (HCE) cell line was used in this study. After growth to confluency, HCE cells were challenged with P. aeruginosa strain 6294 in the presence or absence of 10-6 mol/L VD3 for 4 h, 8 h and 12 h. Gene expression of IL-1 beta, IL-6 and IL-8 was detected by reverse transcription-PCR (RT-PCR) from total RNA extracted from HCE cells. Protein concentrations of IL-1 beta, IL-6 and IL-8 in culture supernatants were measured by ELISA. Addition of VD3 to HCE cells colonized with P. aeruginosa significantly inhibited the expression of IL-1 beta and IL-8 mRNA and protein (P < 0.05). Although the expression of IL-6 mRNA was stimulated at 12 h post-challenge (P < 0.05), the expression of IL-6 protein was inhibited at all time points after the addition of VD3. In conclusion, this study demonstrated that VD3 inhibited the P. aeruginosa-induced expression of IL-1 beta, IL-6 and IL-8 in HCE cells, suggesting that this vitamin may have the potential to become a novel anti-inflammatory agent in ocular disease.