title: The Spectrum of Mild to Severe Psoriasis Vulgaris Is Defined by a Common Activation of IL-17 Pathway Genes, but with Key Differences in Immune Regulatory Genes.
abstract: Mild versus severe psoriasis is often distinguished by clinical measures such as the extent of skin involvement or Psoriasis Area and Severity Index score, both of which use arbitrary boundaries. It is widely assumed that severe psoriasis involves higher levels of skin inflammation, but comparative molecular profiles of mild versus severe disease have not been performed. In this study, we used immunohistochemistry, reverse transcription PCR, and gene arrays to determine the phenotype of North American patients with mild psoriasis (n = 34, mean PASI score = 5.5) versus severe psoriasis (n = 23, mean PASI score = 23.2). Overall, skin inflammation, defined as the sum of T-cell infiltration/activation and IL-17-mediated epidermal responses, was not higher in severe psoriasis lesions. Surprisingly, mild psoriasis was characterized by higher numbers of T cells in skin lesions, higher IL-17A expression, and stronger expression of the core psoriasis transcriptome. In contrast, severe psoriasis was characterized by stronger expression of some epidermal response genes (TGFA, CALM1, SMPD3, and IL1RL2). However, a key molecular distinction was higher expression of negative immune regulatory genes (CTLA4, CD69 and PD-L1) in mild lesions compared with severe psoriasis lesions. These data have important implications for treating psoriasis across the spectrum of disease, as well as for potential mechanisms that allow psoriasis to progress to more extensive cutaneous disease.
authors.affiliation: Laboratory for Investigative Dermatology, The Rockefeller University, New York, New York, USA.
authors.forename: Jaehwan
authors.initials: J
authors.lastname: Kim
authors.affiliation: Innovaderm Research Incorporated, Montreal, Quebec, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Bissonnette
authors.affiliation: Laboratory for Investigative Dermatology, The Rockefeller University, New York, New York, USA.
authors.forename: Jongmi
authors.initials: J
authors.lastname: Lee
authors.affiliation: Laboratory for Investigative Dermatology, The Rockefeller University, New York, New York, USA; The Center for Clinical and Translational Science, The Rockefeller University, New York, New York, USA.
authors.forename: Joel
authors.initials: J
authors.lastname: Correa da Rosa
authors.affiliation: The Center for Clinical and Translational Science, The Rockefeller University, New York, New York, USA; Department of Dermatology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Mayte
authors.initials: M
authors.lastname: Suárez-Fariñas
authors.affiliation: Laboratory for Investigative Dermatology, The Rockefeller University, New York, New York, USA; Division of Dermatology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York, USA.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Lowes
authors.affiliation: Laboratory for Investigative Dermatology, The Rockefeller University, New York, New York, USA. Electronic address: kruegej@rockefeller.edu.
authors.forename: James G
authors.initials: JG
authors.lastname: Krueger
mesh_terms: D005786:Gene Expression Regulation; D005809:Genes, Regulator; D006801:Humans; D007111:Immunity, Cellular; D007150:Immunohistochemistry; D020381:Interleukin-17 / Q000096:biosynthesis / Q000235:genetics*; D008875:Middle Aged; D011565:Psoriasis / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D012313:RNA / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012720:Severity of Illness Index; D012867:Skin / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D020381:Interleukin-17; D012313:RNA