title: Inhibition of activator protein 1 signaling abrogates transforming growth factor β-mediated activation of fibroblasts and prevents experimental fibrosis.
abstract: OBJECTIVE
  To investigate whether c-Jun and c-Fos contribute to the pathologic activation of fibroblasts in systemic sclerosis (SSc) and to evaluate the antifibrotic potential of selective activator protein 1 (AP-1) inhibition.
  
  
  METHODS
  Expression of c-Jun and c-Fos was determined by real-time polymerase chain reaction (PCR) and immunohistochemical analysis. Fibroblasts were stimulated with transforming growth factor β (TGFβ) and incubated with T-5224, a small-molecule inhibitor of AP-1, or were transfected with small interfering RNA (siRNA) duplexes against c-Jun and c-Fos. Collagen synthesis was quantified by real-time PCR and hydroxyproline assay. Differentiation of resting fibroblasts into myofibroblasts was assessed by staining for α-smooth muscle actin and stress fibers. The antifibrotic potential of T-5224 was evaluated in mouse models of dermal fibrosis induced by bleomycin or by adenoviral overexpression of a constitutively active TGFβ receptor type I.
  
  
  RESULTS
  Up-regulation of c-Jun and c-Fos was detected in mouse models of SSc and in the skin and dermal fibroblasts of patients with SSc. Stimulation of healthy fibroblasts with TGFβ induced the expression of c-Jun and c-Fos. Treatment with T-5224 or nucleofection with siRNA directed against c-Jun and c-Fos abrogated the profibrotic effects of TGFβ. T-5224 decreased the release of collagen selectively in SSc fibroblasts. T-5224 was well tolerated and prevented dermal fibrosis induced by bleomycin or by adenoviral activation of TGFβ signaling.
  
  
  CONCLUSIONS
  AP-1 is up-regulated in a TGFβ-dependent manner in SSc. The selective AP-1 inhibitor T-5224 reduced collagen synthesis selectively in SSc fibroblasts and efficiently prevented the development of experimental dermal fibrosis. Thus, AP-1 might be a promising new molecular target for the treatment of SSc.
authors.affiliation: University of Erlangen-Nuremberg, Erlangen, Germany. javouac@me.com
authors.forename: Jérôme
authors.initials: J
authors.lastname: Avouac
authors.forename: Katrin
authors.initials: K
authors.lastname: Palumbo
authors.forename: Michal
authors.initials: M
authors.lastname: Tomcik
authors.forename: Pawel
authors.initials: P
authors.lastname: Zerr
authors.forename: Clara
authors.initials: C
authors.lastname: Dees
authors.forename: Angelika
authors.initials: A
authors.lastname: Horn
authors.forename: Britta
authors.initials: B
authors.lastname: Maurer
authors.forename: Alfiya
authors.initials: A
authors.lastname: Akhmetshina
authors.forename: Christian
authors.initials: C
authors.lastname: Beyer
authors.forename: Anika
authors.initials: A
authors.lastname: Sadowski
authors.forename: Holm
authors.initials: H
authors.lastname: Schneider
authors.forename: Shunichi
authors.initials: S
authors.lastname: Shiozawa
authors.forename: Oliver
authors.initials: O
authors.lastname: Distler
authors.forename: Georg
authors.initials: G
authors.lastname: Schett
authors.forename: Yannick
authors.initials: Y
authors.lastname: Allanore
authors.forename: Jörg H W
authors.initials: JH
authors.lastname: Distler
mesh_terms: D000818:Animals; D001577:Benzophenones / Q000494:pharmacology; D001761:Bleomycin / Q000633:toxicity; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis / Q000187:drug effects; D004195:Disease Models, Animal; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005355:Fibrosis / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D012595:Scleroderma, Systemic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C568912:3-(5-(4-(cyclopentyloxy)-2-hydroxybenzoyl)-2-((3-hydroxy-1,2-benzisoxazol-6-yl)methoxy)phenyl)propionic acid; D001577:Benzophenones; D007555:Isoxazoles; D016760:Proto-Oncogene Proteins c-fos; D034741:RNA, Small Interfering; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta; D001761:Bleomycin; D003094:Collagen; D048031:JNK Mitogen-Activated Protein Kinases