title: The immune-modulating cytokine and endogenous Alarmin interleukin-33 is upregulated in skin exposed to inflammatory UVB radiation.
abstract: The cellular and molecular mechanisms by which UV radiation modulates inflammation and immunity while simultaneously maintaining skin homeostasis is complex and not completely understood. Similar to the effects of UV, IL-33 has potent immune-modulating properties that are mediated by the downstream induction of cytokines and chemokines. We have discovered that exposure of mice in vivo or human skin samples ex vivo to inflammatory doses of UVB induced IL-33 expression within the epidermal and dermal skin layers. Using a combination of murine cell lines and primary human cells, we demonstrate that both UV and the oxidized lipid platelet activating factor induce IL-33 expression in keratinocytes and dermal fibroblasts. Highlighting the significance of these results, we found that administering IL-33 to mice in vivo suppressed the induction of Th1-mediated contact hypersensitivity responses. This may have consequences for skin cancer growth because UV-induced squamous cell carcinomas that evade immunological destruction were found to express significantly higher levels of IL-33. Finally, we demonstrate that dermal mast cells and skin-infiltrating neutrophils closely associate with UV-induced IL-33-expressing fibroblasts. Our results therefore identify and support a role for IL-33 as an important early danger signal produced in response to inflammation-inducing UV radiation.
authors.affiliation: Cellular Immunology Group, Department of Infectious Diseases and Immunology, Sydney Medical School, University of Sydney, New South Wales, Australia. scott.byrne@sydney.edu.au
authors.forename: Scott Napier
authors.initials: SN
authors.lastname: Byrne
authors.forename: Clare
authors.initials: C
authors.lastname: Beaugie
authors.forename: Clare
authors.initials: C
authors.lastname: O'Sullivan
authors.forename: Sarah
authors.initials: S
authors.lastname: Leighton
authors.forename: Gary M
authors.initials: GM
authors.lastname: Halliday
mesh_terms: D000328:Adult; D000818:Animals; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000209:etiology* / Q000473:pathology; D005260:Female; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects; D005455:Fluorescent Antibody Technique; D006801:Humans; D007249:Inflammation / Q000209:etiology* / Q000473:pathology; D000067596:Interleukin-33; D007378:Interleukins / Q000378:metabolism*; D015603:Keratinocytes / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects; D010972:Platelet Activating Factor / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects*; D012878:Skin Neoplasms / Q000209:etiology* / Q000473:pathology; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: C506536:IL33 protein, human; C506535:Il33 protein, mouse; D000067596:Interleukin-33; D007378:Interleukins; D010972:Platelet Activating Factor; D012333:RNA, Messenger