Protective effects of cyclooxygenase-2 inhibitors on narrow-band ultraviolet B-irradiated epidermal Ia+ Langerhans cells and Thy-1+ dendritic epidermal T cells in mice

Cyclooxygenase (COX)-2 inhibitors are known to be used as chemopreventative agents against certain malignancies. Thus far, there has been very limited information on whether COX-2 inhibitors protect against chronic narrow-band UVB (NB-UVB)-induced immunosuppression. The present study investigated the effect of nonselective and specific COX-2 inhibitors, indomethacin and celecoxib, on epidermal Ia(+) Langerhans cells (LCs) and Thy-1(+) dendritic epidermal T cells (DETCs) in mice irradiated with NB-UVB. Sixty female BALB/c mice were divided randomly into the control group (sham) and the experimental groups (irradiated with NB-UVB for 17 weeks, further divided into five groups according to the diets containing different concentrations of either COX-2 inhibitors). Alterations in the density and morphology of epidermal Ia(+) LCs and Thy-1(+) DETCs in mice were documented using fluorescence microscopy. Chronic NB-UVB irradiation substantially decreased the density and altered the morphology of the epidermal Ia(+) LCs and Thy-1(+) DETCs in control mice. The dietary supplementation of both COX-2 inhibitors displayed a dosage-dependent protective effect on the murine dendritic cells irradiated by NB-UVB. In conclusion, COX-2 inhibitors protected against chronic NB-UVB-induced density and morphologic changes in epidermal Ia(+) LCs and Thy-1(+) DETCs in mice.