title: T regulatory cells and related immunoregulatory factors in polymorphic light eruption following ultraviolet A1 challenge.
abstract: BACKGROUND
  Polymorphic light eruption (PLE) is considered to be an autoimmune-mediated skin condition in which the normal ultraviolet (UV)-induced local immunosuppression appears to be absent, leading to recognition of photoinduced autoantigens and subsequent inflammation.
  
  
  OBJECTIVE
  To investigate T regulatory cells (Tregs) and related immunoregulatory factors in PLE lesions and controls.
  
  
  METHODS
  Skin biopsies were performed in 13 patients with UVA1-challenged PLE, 12 female patients with chronic discoid lupus erythematosus (CDLE) and 11 healthy controls who had exposure to UVA1. Immunohistochemistry and four-colour immunofluorescence studies were performed.
  
  
  RESULTS
  Patients with CDLE and UVA1-exposed controls showed significantly decreased epidermal immunoreactivity for CD1a compared with patients with PLE (P = 0·0001). Four-colour immunofluorescence revealed a median percentage of CD4+CD25+FOXP3+ Tregs of 7·6% (range 3·7-13·6%) in PLE, a median of 11·7% (range 9·5-13·9%) in CDLE and a median of 3·4% (range 0-6·8%) in controls. Compared with UVA1-exposed controls, PLE and CDLE lesions showed significantly decreased transforming growth factor (TGF)-β1 immunoreactivity in the epidermis (P = 0·0003). In PLE lesions, we observed significantly decreased interleukin (IL)-10 expression compared with CDLE (P = 0·022). In the dermis, receptor activator of nuclear factor-κB ligand (RANKL) expression was increased in UVA1-exposed controls compared with PLE and CDLE (P = 0·018).
  
  
  CONCLUSIONS
  Similar to CDLE lesions, UVA1-challenged PLE lesions display an altered immunoregulatory network, as indicated by decreased epidermal or dermal expression of TGF-β1, IL-10 and RANKL, and a relatively low number of Tregs, particularly when compared with other inflammatory skin conditions reported in the literature.
authors.affiliation: Department of Dermatology, Ruhr-University Bochum, Gudrunstraße 56, 44791, Bochum, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Gambichler
authors.forename: S
authors.initials: S
authors.lastname: Terras
authors.forename: P
authors.initials: P
authors.lastname: Kampilafkos
authors.forename: A
authors.initials: A
authors.lastname: Kreuter
authors.forename: M
authors.initials: M
authors.lastname: Skrygan
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology; D007150:Immunohistochemistry; D016753:Interleukin-10 / Q000378:metabolism; D008179:Lupus Erythematosus, Discoid / Q000276:immunology*; D010787:Photosensitivity Disorders / Q000276:immunology*; D053245:RANK Ligand / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D053245:RANK Ligand; D053773:Transforming Growth Factor beta1; D016753:Interleukin-10