Objectives Systemic sclerosis (SSc) is a complex disease of unknown aetiology in which inflammation and fibrosis lead to multiple organ damage. There is currently no effective therapy that can halt the progression of fibrosis or reverse it, thus studies that provide novel insights into disease pathogenesis and identify novel potential therapeutic targets are critically needed.
Methods We used global gene expression and genome-wide DNA methylation analyses of dermal fibroblasts (dFBs) from a unique cohort of twins discordant for SSc to identify molecular features of this pathology. We validated the findings using in vitro, ex vivo and in vivo models.
Results Our results revealed distinct differentially expressed and methylated genes, including several transcription factors involved in stem cell differentiation and developmental programmes (KLF4, TBX5, TFAP2A and homeobox genes) and the microRNAs miR-10a and miR-10b which target several of these deregulated genes. We show that KLF4 expression is reduced in SSc dFBs and its expression is repressed by TBX5 and TFAP2A. We also show that KLF4 is antifibrotic, and its conditional knockout in fibroblasts promotes a fibrotic phenotype.
Conclusions Our data support a role for epigenetic dysregulation in mediating SSc susceptibility in dFBs, illustrating the intricate interplay between CpG methylation, miRNAs and transcription factors in SSc pathogenesis, and highlighting the potential for future use of epigenetic modifiers as therapies.
- systemic sclerosis
Data availability statement
Data are available in a public, open access repository. Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information.
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MM, LR and NT are joint first authors.
Handling editor Josef S Smolen
MM, LR and NT contributed equally.
Contributors CAF-B is the guarantor for this study. CAF-B designed and coordinated the study. CAF-B and TAM recruited the patients. TAM did history and physical examinations and disease subtyping of patients. CAF-B and NT processed the skin biopsies, cultured fibroblasts and extracted DNA and RNA. SH confirmed the zygosity of the twins. MM and NT conducted the qPCR and gain/loss of function experiments. KDZ, PSR, WAdS, GH, NT, LRP, BW and CDL analysed the data. MP-G and LRP generated the KLF4 conditional knock out mice. MM, LR, PSR, and CFB wrote the manuscript. All authors were involved in critical review, editing, revision and approval of the final manuscript.
Funding This study was Supported by the US National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (NIH) under Awards Numbers K24 AR060297 (CFB), K01 AR067280 (PSR), T32 AR050958 (LR), and R35 HL144979 (MPG), by the Parker B. Francis Fellowship (LRP), and by the Scleroderma Foundation (CFB).
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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