The heterodimeric form of nuclear factor kappaB (NF-kappaB), NF-kappaB1/RelA, is one of the pluripotential transcription factors that activates various genes encoding cytokines and cell adhesion molecules. To clarify the involvement of radical oxygen species in the NF-kappaB activation pathway in keratinocytes, we examined the effect of hydrogen peroxide (H(2)O(2)) on the activation of NF-kappaB in cultured normal human epidermal keratinocytes. After the treatment of keratinocytes with 300 microM H(2)O(2), a translocation of NF-kappaB from the cytoplasm to nucleus was observed in an immunofluorescence study using anti-human NF-kappaB1 and anti-human RelA antibodies. Specific DNA binding was observed with the nuclear extract prepared from the H(2)O(2)-treated keratinocytes by the electrophoretic mobility shift assay. The presence of N-acetyl-L-cysteine or pyrrolidine dithiocarbamate during H(2)O(2) treatment prevented the nuclear localization of NF-kappaB. The involvement of radical oxygen species in the NF-kappaB activation pathway was suggested. Pretreatment of keratinocytes with 10 ng/ml of recombinant human interleukin-10 (IL-10) for 24 h suppressed the nuclear translocation of NF-kappaB induced by H(2)O(2). IL-10, which increases in ultraviolet-irradiated skin and suppresses delayed type hypersensitivity in vivo, may play an inhibitory role in cutaneous inflammation by inhibiting the NF-kappaB activation pathway in keratinocytes.
