title: Histone Demethylation and Toll-like Receptor 8-Dependent Cross-Talk in Monocytes Promotes Transdifferentiation of Fibroblasts in Systemic Sclerosis Via Fra-2.
abstract: To investigate whether epigenetic changes can modulate monocytes to produce tissue inhibitor of metalloproteinases 1 (TIMP-1) via Fra-2 (an activator protein 1 [AP-1] family member), a novel downstream mediator that promotes fibrogenesis.
  
  
  
  AP-1 transcription factors and TIMP-1 expression were measured in monocytes from systemic sclerosis (SSc) patients and healthy controls. Involvement of Fra-2 in the regulation of TIMP-1 following treatment with Toll-like receptor 8 (TLR-8) agonist was investigated using a luciferase activity assay and chromatin immunoprecipitation (ChIP) analysis. Expression of TIMP-1 and Fra-2 was determined in response to TLR-8 treatment and to different histone modifications, including 3'-deazaneplanocin (DZNep) and apicidin. Fibroblasts from healthy controls were cocultured with DZNep plus TLR-8-treated healthy control monocytes.
  
  
  
  Up-regulation of Fra-2 was detected in bleomycin-challenged mice and in skin biopsy samples from SSc patients. Enhanced expression of Fra-2 and TIMP-1 was correlated in SSc monocytes (P = 0.021). The expression of Fra-1 was significantly reduced (P = 0.037) in SSc monocytes. Inhibiting AP-1 activity reduced TIMP-1 production in TLR-8-stimulated monocytes from healthy controls and SSc patients. ChIP experiments revealed binding of Fra-2 to the TIMP-1 promoter. Stimulation with DZNep plus TLR-8 enhanced Fra-2 and TIMP-1 expression in healthy control monocytes, whereas TLR-8 plus apicidin repressed Fra-2 and TIMP-1 expression. Finally, healthy control monocytes treated with DZNep plus TLR-8 induced strong production of α-smooth muscle actin in dermal fibroblasts, which was inhibited by TIMP-1-blocking antibody.
  
  
  
  These data demonstrate a novel role of histone demethylation induced by DZNep on Fra-2-mediated TIMP-1 production by monocytes in the presence of TLR-8 agonist. This consequently orchestrates the transdifferentiation of fibroblasts, a key event in the pathogenesis of SSc.
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, L. Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland, and National Institute of Geriatrics, Rheumatology, and Rehabilitation, Warsaw, Poland.
authors.forename: Marzena
authors.identifier: 0000-0002-0961-6130
authors.initials: M
authors.lastname: Ciechomska
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, and Durham University, School of Biological and Biomedical Sciences, Durham, UK.
authors.forename: Steven
authors.initials: S
authors.lastname: O'Reilly
authors.affiliation: Durham University, School of Biological and Biomedical Sciences, Durham, UK.
authors.forename: Stefan
authors.initials: S
authors.lastname: Przyborski
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Fiona
authors.initials: F
authors.lastname: Oakley
authors.affiliation: Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, and Wroclaw Medical University, Wroclaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Bogunia-Kubik
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, and University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: van Laar
mesh_terms: D000818:Animals; D054338:Cell Transdifferentiation; D044127:Epigenesis, Genetic; D005347:Fibroblasts / Q000166:cytology*; D051921:Fos-Related Antigen-2 / Q000502:physiology*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008745:Methylation; D051379:Mice; D008875:Middle Aged; D009000:Monocytes / Q000502:physiology*; D020239:Receptor Cross-Talk; D012595:Scleroderma, Systemic / Q000378:metabolism* / Q000473:pathology*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000502:physiology*; D051200:Toll-Like Receptor 8 / Q000502:physiology*
chemical_list: C497872:FOSL2 protein, human; D051921:Fos-Related Antigen-2; C497873:Fosl2 protein, mouse; D006657:Histones; C560822:TIMP1 protein, human; C560825:Timp1 protein, mouse; D019715:Tissue Inhibitor of Metalloproteinase-1; D051200:Toll-Like Receptor 8