title: Interleukin-19 downregulates interleukin-4-induced eotaxin production in human nasal fibroblasts.
abstract: BACKGROUND
  Interleukin-19 (IL-19), a member of the IL-10 family, is characterized as the cytokine suppressing the release and function of several proinflammatory cytokines. For regulation of local reaction in allergic rhinitis (AR), IL-19 might play an especially important role.
  
  
  METHODS
  We examined effects of IL-19 on IL-4-induced eotaxin production by human nasal fibroblasts. Early receptor-mediated events (expression of the suppressors of cytokine signaling (SOCS) and phosphorylation of signal transducer and activator of transcription 6 [STAT6]) by IL-19 was examined. Knockdown methods by RNAi were administered to investigate the involvement of those signal transductions.
  
  
  RESULTS
  Pretreatment with IL-19 downregulates IL-4-induced eotaxin production, but not interferon-γ(IFN-γ)-induced RANTES. Pretreatment with IL-19 suppressed the IL-4-induced STAT6 phosphorylation. The IL-19 induced SOCS-1, but not SOCS-3 or SOCS-5. The SOCS-1 knockdown by RNAi diminished pretreatment with IL-19-induced down-regulation of eotaxin production.
  
  
  CONCLUSIONS
  These results suggest that IL-19 down-regulates IL-4-induced eotaxin production via SOCS-1 in human nasal fibroblasts. In non-hematopoietic cells in AR, IL-19 might be an immunosuppressive factor.
authors: Department of Otorhinolaryngology, Osaka Medical College, Osaka, Japan.
authors: Masaaki
authors: M
authors: Higashino
authors: Tetsuji
authors: T
authors: Takabayashi
authors: Noboru
authors: N
authors: Takahashi
authors: Masayuki
authors: M
authors: Okamoto
authors: Norihiko
authors: N
authors: Narita
authors: Akihiro
authors: A
authors: Kojima
authors: Sawako
authors: S
authors: Hyo
authors: Ryo
authors: R
authors: Kawata
authors: Hiroshi
authors: H
authors: Takenaka
authors: Shigeharu
authors: S
authors: Fujieda