Glucocorticoids augment the chemically induced production and gene expression of interleukin-1alpha through NF-kappaB and AP-1 activation in murine epidermal cells.

To clarify the mechanism of the glucocorticoid-induced augmentation of skin response, we attempted to demonstrate the modulatory effect of glucocorticoids on the regulation of cytokines produced by keratinocytes stimulated with various chemicals in vitro. Haptens, irritants, and a superantigen (staphylococcal enterotoxin B) induced a significant release of interleukin-1alpha and tumor necrosis factor alpha, but not interleukin-10, from a murine keratinocyte cell line, Pam 212 cells. Glucocorticoids (10(-6)-10(-12) M) significantly augmented the production of interleukin-1alpha by Pam 212 cells at both the protein and mRNA levels when stimulated by either haptens or irritants, but not by staphylococcal enterotoxin B, whereas glucocorticoids alone had no effect. In contrast, glucocorticoids had no effect on the production of tumor necrosis factor alpha and interleukin-10 by chemically stimulated Pam 212 cells. Electrophoretic mobility shift assays revealed that chemical stimulation induced NF-kappaB activation in Pam 212 cells; however, augmented NF-kappaB activation by 10(-6)-10(-8) M of glucocorticoids was observed in Pam 212 cells stimulated by both haptens and irritants, but not by staphylococcal enterotoxin B. Furthermore, pyrrolidine dithiocarbamate inhibited the hapten-induced interleukin-1alpha production and NF-kappaB expression by Pam 212 cells. Pyrrolidine dithiocarbamate did not completely abrogate the hapten-induced interleukin-1alpha production augmented by glucocorticoids, however. To determine the effect on transcription factors other than NF-kappaB, AP-1 activity was examined by electrophoretic mobility shift assays. Hapten was founded to induce AP-1 activation in Pam 212 cells. In addition, AP-1 activation was augmented in the hapten-stimulated Pam 212 cells in the presence of 10(-8)-10(-10) M of glucocorticoids. The augmented inflammatory reaction by glucocorticoids may therefore reflect the augmentation of interleukin-1alpha production by keratinocytes mediated through the NF-kappaB and AP-1 pathway.