Fli1-haploinsufficient dermal fibroblasts promote skin-localized transdifferentiation of Th2-like regulatory T cells

Ryosuke Saigusa, Yoshihide Asano, Takashi Taniguchi, Megumi Hirabayashi, Kouki Nakamura, Shunsuke Miura, Takashi Yamashita, Takehiro Takahashi, Yohei Ichimura, Tetsuo Toyama, Ayumi Yoshizaki, Maria Trojanowska, Shinichi Sato

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20 Citations (Scopus)

Abstract

Background: Friend leukemia virus integration 1 (Fli1) deficiency, a predisposing factor of systemic sclerosis (SSc), induces SSc-like phenotypes in various cell types. A recent study demonstrated the transdifferentiation of T helper type 2 cell (Th2)-like regulatory T cells (Tregs) in SSc lesional skin through interleukin (IL)-33 produced by fibroblasts. Therefore, we investigated the role of Fli1 deficiency in dermal fibroblast-mediated transdifferentiation of Tregs. Methods: Cytokine expression was assessed in Tregs by flow cytometry and in skin samples and cultivated cells by immunostaining, immunoblotting, and/or qRT-PCR. Fli1 binding to the target gene promoters was examined by chromatin immunoprecipitation. Murine dermal fibroblasts and Tregs were cocultured with or without blocking antibodies against target cytokines. Results: Th2- and Th17-like cell proportions in skin-homing Tregs were increased in bleomycin-treated Fli1 +/- mice compared with bleomycin-treated wild-type mice, whereas Th1-, Th2-, and Th17-like cell proportions in splenic Tregs were comparable. Fli1 +/- fibroblasts overproduced IL-33 and IL-6, in particular IL-33, and Fli1 occupied the IL33 and IL6 promoters in dermal fibroblasts. Importantly, the IL-4-producing cell proportion was significantly higher in wild-type Tregs cocultured with Fli1 +/- fibroblasts than in those cocultured with wild-type fibroblasts, which were canceled by neutralizing anti-IL-33 antibody. Under the same coculture condition, an increased tendency of IL-17A-producing cell proportion, which was possibly mediated by IL-6, was evident. Conclusions: Fli1 haploinsufficiency increases the proportions of Th2- and Th17-like Tregs in bleomycin-induced profibrotic skin conditions, in which IL-33-producing dermal fibroblasts contribute to Th2-like Treg transdifferentiation, suggesting a critical role of Fli1 deficiency in the interaction of dermal fibroblasts with immune cells in pathological skin fibrosis.

Original languageEnglish
Article number23
JournalArthritis Research and Therapy
Volume20
Issue number1
DOIs
Publication statusPublished - 2018 Feb 7

Keywords

  • Fibroblasts
  • Fli1
  • IL-33
  • Regulatory T cells
  • Systemic sclerosis

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