| [ Summary ] |
Several lines of evidence including the existence of the vitamin D receptor (VDR) in cells involved in the immune response suggest the physiological role of 1,25-dihydroxyvitamin D, the active form of vitamin D in immune system. There are many reports describing that 1,25-dihydroxyvitamin D suppresses the production of cytokines such as in terleukin-2, interferon-γ and GM-CSF (granulocyte macrophage colony stimulating factor) in T cells. The transcription factor, NFAT, and VDR mediate the suppressive effect of 1,25-dihydroxyvitamin D. However, the precise mechanism in which these molecules interact with each other on the promoter regions of cytokines genes is different in various cytokines. 1,25-dihydroxyvitamin D also inhibits the function of antigen-presenting cells leading to the immunosuppression. The in vivo data demonstrate that 1,25-dihydroxyvitamin D exerts some effects in autoimmune diseases and the rejection of transplanted organs. Since 1,25-dihydroxyvitamin D has a relatively mild modulating effect on immune response and adverse effects, especially increases in serum calcium levels, it is necesary to develop new vitamin D analogues which addresses these problems. |