1-alpha-24-dihydroxyvitamin-d3 and Dermatitis--Contact

1,24-Dihydroxyvitamin D₃ (tacalcitol), a vitamin D(3) compound, has been used to treat T cell-mediated inflammatory skin diseases such as psoriasis, prurigo and vitiligo. The best-known mechanism of action of this compound is inhibition of the abnormal proliferation of keratinocytes and subsequent maturation; however, its effects on skin T-cell recruitment have not yet been evaluated. Cutaneous lymphocyte-associated antigen (CLA), a surface glycoprotein expressed on T cells, plays a critical role in skin T-cell infiltration. We recently reported that 1,25-dihydroxyvitamin D₃ inhibits skin infiltration of CD4+ T cells by suppressing CLA expression on T cells.. In this study, we investigated the effect of tacalcitol on CLA epitope decoration and on the levels of gut or lymph node homing receptor expression in human T cells.. We cultured human T cells with tacalcitol and analysed the effect on CLA expression and skin-homing ability, and evaluated glycosyltransferase mRNAs. We also performed an in vivo study using an antigen-dependent delayed-type hypersensitivity (DTH) mouse model and investigated the effect of tacalcitol on skin-infiltrating CD4+ T cells.. Tacalcitol downregulated the expression of CLA and, in parallel, the E- and P-selectin ligand function; however, it exerted no effect on other homing receptors. Subcutaneously and intraperitoneally administered tacalcitol downregulated skin infiltration of effector CD4+ T cells in an in vivo DTH mouse model.. These findings suggest that tacalcitol reduces skin inflammation by partially downregulating CLA expression levels.

Topics: Adult; Animals; Antigens, Differentiation, T-Lymphocyte; Cell Movement; Dermatitis, Contact; Dermatologic Agents; Dihydroxycholecalciferols; Disease Models, Animal; Down-Regulation; E-Selectin; Female; Flow Cytometry; Humans; Immunohistochemistry; Male; Membrane Glycoproteins; Mice; P-Selectin; Receptors, Lymphocyte Homing; Skin; T-Lymphocytes