Regulatory effects of 1a,25-dihydroxyvitamin D3 on cytokine production by human corneal epithelial cells

Abstract

Purpose. The topical administration of 1a,25-dihydroxy-vitamin D 3 [1a,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 1a,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 1a,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-1a, IL-1ß, and IL-8 were quantified by ELISA. Results. Significantly lower levels of IL-1a and IL-1ß were detected in supernatants from cells cultured with 1a,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 1a,25(OH) 2 D 3 (p < 0.05). IL-8 production inhibition by 1a,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. 1a,25(OH) 2 D 3 inhibits cytokine (IL-1a, IL-1ß, and IL-8) production by human corneal epithelial cells in vitro. We suspect that 1a,25(OH) 2 D 3 can inhibit LC migration and corneal neovascularization, as is seen in ocular surface inflammation.