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Ultraviolet B Light Stimulates lnterleukin‐20 Expression by Human Epithelial Keratinocytes
Author(s) -
Hunt David W. C.,
Boivin Wendy A.,
Fairley Lindsay A.,
Jovanovic Miroslava M.,
King Diane E.,
Salmon Ruth A.,
Utting Oliver B.
Publication year - 2006
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/2005-08-31-ra-668
Subject(s) - cytokine , proinflammatory cytokine , tumor necrosis factor alpha , microbiology and biotechnology , p38 mitogen activated protein kinases , mapk/erk pathway , viability assay , interleukin , lipopolysaccharide , chemistry , biology , kinase , immunology , inflammation , cell , biochemistry
The proinflammatory cytokine interleukin‐20 (IL‐20) may exert the majority of its activity in the skin. We examined the effect of various treatments including several forms of phototherapy on IL‐20 expression using cultured normal human epithelial keratinocytes (NHEK). Broadband UVB light, recombinant (r) IL‐1 and rIL‐8 increased, while hydrocortisone reduced, NHEK supernatant IL‐20 levels. Elevation of NHEK IL‐20 mRNA and maximal supernatant IL‐20 levels occurred with a UVB light dose (40 mJ cm −2 ) that reduced cell viability by approximately 50%. While this UVB light dose also elevated supernatant IL‐1α and IL‐8 levels, antibody neutralization studies indicated that neither of these cytokines was directly responsible for this increase in IL‐20 expression. However, the elevation in IL‐20 levels was fully inhibited by the p38 mitogen‐activated protein kinase (MAPK) inhibitor SB‐203580, suggesting involvement of this stress signaling pathway in this UVB light response. Photodynamic therapy (PDT) with the photosensitizer lemuteporfin, UVA light, cisplatin, lipopolysaccharide (LPS), tumor necrosis factor‐α (TNF‐α) or recombinant interferon‐γ (rIFN‐γ) either had little effect or decreased NHEK supernatant IL‐20 levels. Reduced IL‐20 levels paralleled the cytotoxic actions of PDT, UVA light or cisplatin and the antiproliferative effect of rIFN‐γ. Neither rIL‐20 supplementation nor anti‐IL‐20 antibody treatments affected cell viability indicating that soluble IL‐20 did not affect the short‐term survival of UVB light‐irradiated NHEK. Stimulation of IL‐20 expression in keratinocytes by UVB light suggests that this cytokine might participate in skin responses to this ever‐present environmental factor and potentially has a role in UV light‐associated dermatoses.