title: Desired response to phototherapy vs photoaggravation in psoriasis: what makes the difference?
abstract: Psoriasis commonly responds beneficially to UV radiation from natural sunlight or artificial sources. Therapeutic mechanisms include the proapoptotic and immunomodulating effects of UV, affecting many cells and involving a variety of pro- and anti-inflammatory cytokines, downregulating the Th17/IL-23 response with simultaneous induction of regulatory immune cells. However, exposure to UV radiation in a subset of psoriasis patients leads to exacerbation of the disease. We herein shed light on the predisposing factors of photosensitive psoriasis, including genetics (such as HLA-Cw*0602 or CARD14), gender and coexisting photodermatoses such as polymorphic light eruption (PLE) in the context of potential molecular mechanisms behind therapeutic photoresponsiveness or photoaggravation. UV-induced damage/pathogen-associated molecular patterns, damage to self-coding RNA (signalling through Toll-like receptors), certain antimicrobial peptides and/or inflammasome activation may induce innate immunity, leading to psoriasis at the site of UV exposure when there is concomitant, predisposing resistance against UV-induced suppression of the adaptive immune response (like in PLE) that otherwise would act to reduce psoriasis.
authors.affiliation: Research Unit for Photodermatology, Department of Dermatology, Medical University of Graz, Graz, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Wolf
authors.affiliation: Research Unit for Photodermatology, Department of Dermatology, Medical University of Graz, Graz, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Weger
authors.affiliation: Research Unit for Photodermatology, Department of Dermatology, Medical University of Graz, Graz, Austria.
authors.forename: VijayKumar
authors.initials: V
authors.lastname: Patra
authors.affiliation: Research Unit for Photodermatology, Department of Dermatology, Medical University of Graz, Graz, Austria.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Gruber-Wackernagel
authors.affiliation: Cellular Photoimmunology Group, Infectious Diseases and Immunology, Sydney Medical School, Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.
authors.forename: Scott N
authors.initials: SN
authors.lastname: Byrne
mesh_terms: D053468:CARD Signaling Adaptor Proteins / Q000235:genetics*; D006162:Guanylate Cyclase / Q000235:genetics*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics*; D010787:Photosensitivity Disorders / Q000235:genetics*; D010789:Phototherapy; D011565:Psoriasis / Q000235:genetics / Q000532:radiotherapy*
chemical_list: D053468:CARD Signaling Adaptor Proteins; D008565:Membrane Proteins; C426243:CARD14 protein, human; D006162:Guanylate Cyclase
keywords: Koebner phenomenon; photoaggravation; photosensitivity; phototherapy; polymorphic light eruption; psoriasis