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

Purpose. The topical administration of 1 alpha,25-dihydroxyvitamin D3 [1 al pha,25(OH)(2)D-3] inhibits Langerhans cell (LC) migration and corneal neova scularization in mice. Since the cytokines that induce LC migration [e.g. i nterleukin-1 (IL-1)] and corneal neovascularization [e.g. interleukin-8 (IL -8)] are produced by human corneal epithelial cells, we investigated the in hibitory effects of 1 alpha,25(OH)(2)D-3 on cytokine production by these ce lls in vitro. Methods. In this experiment, human corneal epithelial cells, cultured in DM EM-FBS until confluence, were then switched to serum-free DMEM containing i nsulin, transferrin, and sodium selenite (DMEM-ITS) for 48 hours. Next, the y were cultured with DMEM-ITS containing 1 alpha,25(OH)(2)D-3 at concentrat ions 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 c oncentrations of IL-1 alpha, IL-1 beta, and IL-8 were quantified by ELISA. Results. Significantly lower levels of IL-1 alpha and IL-1 beta were detect ed in supernatants from cells cultured with 1 alpha,25(OH)(2)D-3 (10(-7) M, 10(-11) M, and 10(-15) M), compared to cells cultured with vehicle only. T his was true at 6 and 12 hours after the addition of 1 alpha,25(OH)(2)D-3 ( p < 0.05). IL-8 production inhibition by 1 alpha,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. 1 alpha,25(OH)(2)D-3 inhibits cytokine (IL-1 alpha, IL-1 beta, and IL-8) production by human corneal epithelial cells in vitro. We suspec t that 1 alpha,25(OH)(2)D-3 can inhibit LC migration and corneal neovascula rization, as is seen in ocular surface inflammation.