Vitamin D3 inhibits proinflammatory cytokines and nitric oxide production by the EOC13 microglial cell line.

In recent years, a neuroimmunomodulatory role for 1,25-dihydroxyvitamine D(3) [1,25(OH)(2)D(3)] has emerged. Microglial cells present a potential target for the effects of this hormone in the brain. This study focuses on the effect of 1,25(OH)(2)D(3) on the expression and production of inflammatory cytokines and nitric oxide (NO) by the EOC13 microglial cell line. The presence of the vitamin D3 receptor in microglia was demonstrated by RT-PCR. 1,25(OH)(2)D(3) inhibited the production of tumor necrosis factor-alpha, interleukin-6, and NO by stimulated microglia in a concentration-related fashion. The production of transforming growth factor-beta1 (TGF-beta1), an anti-inflammatory cytokine, was not modified in the presence of 1,25(OH)(2)D(3), indicating that the effects of 1,25(OH)(2)D(3) may not involve TGF-beta1 regulation. These results show that 1,25(OH)(2)D(3) has direct anti-inflammatory properties on microglia. It further supports the hypothesis that 1,25(OH)(2)D(3) could be involved in the maintenance of the brain homeostasis and may have a therapeutic potential in inflammatory pathologies of the central nervous system. Copyright 2002 Wiley-Liss, Inc.