title: Endothelial-to-mesenchymal transition contributes to endothelial dysfunction and dermal fibrosis in systemic sclerosis.
abstract: OBJECTIVE
  Systemic sclerosis (SSc) features multiorgan fibrosis orchestrated predominantly by activated myofibroblasts. Endothelial-to-mesenchymal transition (EndoMT) is a transdifferentiation by which endothelial cells (ECs) lose their specific morphology/markers and acquire myofibroblast-like features. Here, we determined the possible contribution of EndoMT to the pathogenesis of dermal fibrosis in SSc and two mouse models.
  
  
  METHODS
  Skin sections were immunostained for endothelial CD31 or vascular endothelial (VE)-cadherin in combination with α-smooth muscle actin (α-SMA) myofibroblast marker. Dermal microvascular ECs (dMVECs) were prepared from SSc and healthy skin (SSc-dMVECs and H-dMVECs). H-dMVECs were treated with transforming growth factor-β1 (TGFβ1) or SSc and healthy sera. Endothelial/mesenchymal markers were assessed by real-time PCR, immunoblotting and immunofluorescence. Cell contractile phenotype was assayed by collagen gel contraction.
  
  
  RESULTS
  Cells in intermediate stages of EndoMT were identified in dermal vessels of either patients with SSc or bleomycin-induced and urokinase-type plasminogen activator receptor (uPAR)-deficient mouse models. At variance with H-dMVECs, SSc-dMVECs exhibited a spindle-shaped appearance, co-expression of lower levels of CD31 and VE-cadherin with myofibroblast markers (α-SMA+ stress fibres, S100A4 and type I collagen), constitutive nuclear localisation of the EndoMT driver Snail1 and an ability to effectively contract collagen gels. Treatment of H-dMVECs either with SSc sera or TGFβ1 resulted in the acquisition of a myofibroblast-like morphology and contractile phenotype and downregulation of endothelial markers in parallel with the induction of mesenchymal markers. Matrix metalloproteinase-12-dependent uPAR cleavage was implicated in the induction of EndoMT by SSc sera.
  
  
  CONCLUSIONS
  In SSc, EndoMT may be a crucial event linking endothelial dysfunction and development of dermal fibrosis.
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, University of Florence, Florence, Italy.
authors.forename: Mirko
authors.identifier: http://orcid.org/0000-0003-3956-8480
authors.initials: M
authors.lastname: Manetti
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Internal Medicine, Rheumatology Unit, Azienda Ospedaliero-Universitaria Careggi (AOUC), University of Florence, Florence, Italy.
authors.forename: Eloisa
authors.initials: E
authors.lastname: Romano
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, University of Florence, Florence, Italy.|Department of Experimental and Clinical Medicine, Section of Internal Medicine, Rheumatology Unit, Azienda Ospedaliero-Universitaria Careggi (AOUC), University of Florence, Florence, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Rosa
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Internal Medicine, Rheumatology Unit, Azienda Ospedaliero-Universitaria Careggi (AOUC), University of Florence, Florence, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Guiducci
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Internal Medicine, Rheumatology Unit, Azienda Ospedaliero-Universitaria Careggi (AOUC), University of Florence, Florence, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Bellando-Randone
authors.affiliation: Department of Translational Medical Sciences and Center for Basic and Clinical Immunology Research, University of Naples Federico II, Naples, Italy.
authors.forename: Amato
authors.initials: A
authors.lastname: De Paulis
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, University of Florence, Florence, Italy.
authors.forename: Lidia
authors.initials: L
authors.lastname: Ibba-Manneschi
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Internal Medicine, Rheumatology Unit, Azienda Ospedaliero-Universitaria Careggi (AOUC), University of Florence, Florence, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Matucci-Cerinic
mesh_terms: D000199:Actins / Q000032:analysis / Q000378:metabolism; D000818:Animals; D001761:Bleomycin; D015820:Cadherins / Q000032:analysis / Q000378:metabolism; D016022:Case-Control Studies; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000473:pathology*; D004727:Endothelium / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D058750:Epithelial-Mesenchymal Transition; D005355:Fibrosis; D006801:Humans; D008297:Male; D053508:Matrix Metalloproteinase 12 / Q000097:blood; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D055806:Microvessels / Q000737:chemistry / Q000473:pathology; D010641:Phenotype; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis / Q000378:metabolism; D000071999:S100 Calcium-Binding Protein A4 / Q000378:metabolism; D012595:Scleroderma, Systemic / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D044967:Serum; D012867:Skin / Q000098:blood supply / Q000473:pathology*; D000071250:Snail Family Transcription Factors / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000378:metabolism
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D015820:Cadherins; D024042:Collagen Type I; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D000071999:S100 Calcium-Binding Protein A4; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors; D053773:Transforming Growth Factor beta1; C544013:alpha-smooth muscle actin, mouse; D001761:Bleomycin; D014568:Urokinase-Type Plasminogen Activator; D053508:Matrix Metalloproteinase 12
keywords: Fibroblasts; Qualitative research; Systemic Sclerosis