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

Abstract

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. 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. 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). 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.