title: Distribution of IL-31 and its receptor expressing cells in skin of atopic dermatitis.
abstract: BACKGROUND
  To understand the clinical segments of IL-31 signaling blockade therapy in pruritus of atopic dermatitis (AD), direct detection of the target proteins in the diseased tissues will provide crucial information. There is a lack of direct evidence concerning the cellular origin of IL-31 in AD skins, and data on the expression of IL-31RA in AD are inconsistent. Also, there is no available information regarding IL-31RA protein expression in human dorsal root ganglia (DRG), which mediates the sensation of itch and is the long-suspected source of the protein.
  
  
  OBJECTIVE
  We sought to obtain direct evidence concerning the distribution of IL-31- and IL-31RA-protein expressing cells and their characteristics in AD skin samples and in human DRG.
  
  
  METHODS
  IL-31 was detected immunohistochemically in AD skins, and representative sections were double stained with IL-31 and several immune-markers. IL-31RA was stained immunohistochemically in AD skins and normal human DRG, and representative AD skins were double stained with IL-31RA and PGP9.5 (a nerve marker).
  
  
  RESULTS
  IL-31-positive cells were observed as mononuclear infiltrating cells and as CD11b co-expressing cells in severe AD samples. As for IL-31RA, positive reactions were detected in keratinocytes and nerve fibers in the dermis of AD and in the neurons of normal DRG.
  
  
  CONCLUSIONS
  The detection of IL-31 in infiltrating cells of severe AD skin and of IL-31RA in nerve fibers of AD dermis and normal DRG indicates IL-31 signaling may be a contributing factor in the persistence and exacerbation of AD skin lesions.
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., 1-135 Komakado, Gotemba-shi, Shizuoka 412-8513, Japan. Electronic address: katoath@chugai-pharm.co.jp.
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Kato
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., 1-135 Komakado, Gotemba-shi, Shizuoka 412-8513, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Fujii
authors.affiliation: Chugai Research Institute for Medical Science Inc., 1-135 Komakado, Gotemba-shi, Shizuoka 412-8513, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., 1-135 Komakado, Gotemba-shi, Shizuoka 412-8513, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Takashima
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., 1-135 Komakado, Gotemba-shi, Shizuoka 412-8513, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Matsushita
authors.affiliation: Department of Geriatric and Environmental Dermatology, Nagoya City University Graduate School of Medical Sciences, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya-shi, Aichi 467-8602, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Furuhashi
authors.affiliation: Department of Geriatric and Environmental Dermatology, Nagoya City University Graduate School of Medical Sciences, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya-shi, Aichi 467-8602, Japan.
authors.forename: Akimichi
authors.initials: A
authors.lastname: Morita
mesh_terms: D003876:Dermatitis, Atopic / Q000378:metabolism*; D006801:Humans; D007378:Interleukins / Q000378:metabolism*; D018123:Receptors, Interleukin / Q000378:metabolism*; D012867:Skin / Q000378:metabolism
chemical_list: C502187:IL31 protein, human; C502188:IL31RA protein, human; D007378:Interleukins; D018123:Receptors, Interleukin
keywords: Atopic dermatitis; CD11b; Dorsal root ganglia; IL-31; IL-31RA; Nerve-fibers