Regulatory effects of 1alpha,25-dihydroxyvitamin D(3) on cytokine production by human corneal epithelial cells.

Purpose: The topical administration of 1alpha,25-dihydroxy-vitamin D(3) [1alpha,25(OH)(2)D(3) ] inhibits Langerhans cell (LC) migration and corneal neovascularization in mice. Since the cytokines that induce LC migration [e.g. interleukin-1 (IL-1)] and corneal neovascularization [e.g. interleukin-8 (IL-8)] are produced by human corneal epithelial cells, we investigated the inhibitory effects of 1alpha,25(OH)(2)D( 3) on cytokine production by these cells in vitro.
Methods: In this experiment, human corneal epithelial cells, cultured in DMEM-FBS until confluence, were then switched to serum-free DMEM containing insulin, transferrin, and sodium selenite (DMEM-ITS) for 48 hours. Next, they were cultured with DMEM-ITS containing 1alpha,25(OH)(2)D(3 ) at concentrations of 10(-7) M, 10(-11) M, or 10( -15) M, and vehicle only (0.1% ethanol). After 6 or 12 hours in this culture, the supernatants were collected and concentrations of IL-1alpha, IL-1b, and IL-8 were quantified by ELISA.
Results: Significantly lower levels of IL-1alpha and IL-1b were detected in supernatants from cells cultured with 1alpha, 25(OH)(2)D( 3) (10(-7) M, 10(-11) M, and 10(-15) M), compared to cells cultured with vehicle only. This was true at 6 and 12 hours after the addition of 1alpha,25(OH)(2)D(3) (p < 0.05). IL-8 production inhibition by 1alpha,25(OH)(2)D(3), on the other hand, was detected at 6 hours (p < 0.0005) but not at 12 hours (p> 0.1).
Conclusions: 1alpha,25(OH)(2)D(3) inhibits cytokine (IL-1alpha, IL-1b, and IL-8) production by human corneal epithelial cells in vitro. We suspect that 1alpha,25(OH)(2)D(3) can inhibit LC migration and corneal neovascularization, as is seen in ocular surface inflammation.