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

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

doi:10.1186/s13075-018-1521-3

Ryosuke Saigusa, Shunsuke Miura + Show 11 more

Open Access

https://doi.org/10.1186/s13075-018-1521-3

Copy DOI

Abstract

BackgroundFriend 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.MethodsCytokine 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.ResultsTh2- 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.ConclusionsFli1 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.

Highlights

Friend leukemia virus integration 1 (Fli1) deficiency, a predisposing factor of systemic sclerosis (SSc), induces SSc-like phenotypes in various cell types
Given that IL-1β and tumor necrosis factor (TNF)-α induce the expression of IL-33 in dermal fibroblasts [29], we investigated whether these molecules affect the occupancy of Fli1 on the IL33 promoter by performing chromatin immunoprecipitation (ChIP) analysis, showing that both of IL-1β and Tumor necrosis factor-α (TNF-α) induced the dissociation of Fli1 from the promoter (Fig. 2g)
We proposed a novel notion that Fli1 deficiency regulates skin-localized transdifferentiation of Th2-like Regulatory T cell (Treg) through IL-33 and possibly that a b c of Th17-like Tregs through IL-6, both of which are produced by dermal fibroblasts

Summary

Introduction

Friend leukemia virus integration 1 (Fli1) deficiency, a predisposing factor of systemic sclerosis (SSc), induces SSc-like phenotypes in various cell types. Mice with simultaneous haploinsufficiency of the Fli and Klf genes, both of which are epigenetically suppressed in SSc dermal fibroblasts, spontaneously develop the three cardinal features of SSc, including immune abnormalities, vasculopathy, and tissue fibrosis [17]. These animal models are useful for obtaining a clue to understanding the role of certain cells and to elucidating the mechanisms of disease-modifying drugs in SSc [18, 19]

Methods

Results

Discussion

Conclusion