Modulation of TGF-beta 1 production from human keratinocytes by UVB.

Transforming growth factor-beta (TGF-beta) plays an important role not only in cell growth control but also in inflammation and immunoregulation. There are at least five different isoforms of TGF-beta. TGF-beta 1 has a large variety of biological functions including the modulation of inflammation and the immune system and has most extensively been studied in skin. Since ultraviolet B (UVB) is known to induce skin erythema and immunosuppression, we sought to examine whether UVB would alter the expression and production of TGF-beta 1 in normal human keratinocytes. Using reverse transcription-polymerase chain reaction (RT-PCR), constitutive expression of TGF-beta 1 mRNA was detected in keratinocytes and the level of TGF-beta 1 mRNA was increased 4 and 8 h after 300 J/m2 UVB irradiation. Production of TGF-beta 1 protein in culture supernatants assayed by ELISA was also increased at 24 h after irradiation. Cycloheximide treatment blocked this TGF-beta 1 protein induction indicating de novo protein synthesis of TGF-beta 1 from keratinocytes induced by UVB. These results suggest a possible role for TGF-beta 1 in UVB-induced skin inflammation and immunosuppression.