title: Endothelial injury in a transforming growth factor β-dependent mouse model of scleroderma induces pulmonary arterial hypertension.
abstract: OBJECTIVE
  To delineate the constitutive pulmonary vascular phenotype of the TβRIIΔk-fib mouse model of scleroderma, and to selectively induce pulmonary endothelial cell injury using vascular endothelial growth factor (VEGF) inhibition to develop a model with features characteristic of pulmonary arterial hypertension (PAH).
  
  
  METHODS
  The TβRIIΔk-fib mouse strain expresses a kinase-deficient transforming growth factor β (TGFβ) receptor type II driven by a fibroblast-specific promoter, leading to ligand-dependent up-regulation of TGFβ signaling, and replicates key fibrotic features of scleroderma. Structural, biochemical, and functional assessments of pulmonary vessels, including in vivo hemodynamic studies, were performed before and following VEGF inhibition, which induced pulmonary endothelial cell apoptosis. These assessments included biochemical analysis of the TGFβ and VEGF signaling axes in tissue sections and explanted smooth muscle cells.
  
  
  RESULTS
  In the TβRIIΔk-fib mouse strain, a constitutive pulmonary vasculopathy with medial thickening, a perivascular proliferating chronic inflammatory cell infiltrate, and mildly elevated pulmonary artery pressure resembled the well-described chronic hypoxia model of pulmonary hypertension. Following administration of SU5416, the pulmonary vascular phenotype was more florid, with pulmonary arteriolar luminal obliteration by apoptosis-resistant proliferating endothelial cells. These changes resulted in right ventricular hypertrophy, confirming hemodynamically significant PAH. Altered expression of TGFβ and VEGF ligand and receptor was consistent with a scleroderma phenotype.
  
  
  CONCLUSIONS
  In this study, we replicated key features of systemic sclerosis-related PAH in a mouse model. Our results suggest that pulmonary endothelial cell injury in a genetically susceptible mouse strain triggers this complication and support the underlying role of functional interplay between TGFβ and VEGF, which provides insight into the pathogenesis of this disease.
authors.affiliation: University College London Medical School, Royal Free Campus, London, UK.
authors.forename: Emma C
authors.initials: EC
authors.lastname: Derrett-Smith
authors.forename: Audrey
authors.initials: A
authors.lastname: Dooley
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Gilbane
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Trinder
authors.forename: Korsa
authors.initials: K
authors.lastname: Khan
authors.forename: Reshma
authors.initials: R
authors.lastname: Baliga
authors.forename: Alan M
authors.initials: AM
authors.lastname: Holmes
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Hobbs
authors.forename: David
authors.initials: D
authors.lastname: Abraham
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Denton
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D000818:Animals; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000503:physiopathology*; D065627:Familial Primary Pulmonary Hypertension; D005260:Female; D006976:Hypertension, Pulmonary / Q000209:etiology / Q000235:genetics / Q000503:physiopathology*; D000860:Hypoxia / Q000235:genetics / Q000503:physiopathology; D007211:Indoles / Q000494:pharmacology; D007763:Lac Operon; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011652:Pulmonary Circulation / Q000502:physiology*; D011758:Pyrroles / Q000494:pharmacology; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor / Q000037:antagonists & inhibitors; D012595:Scleroderma, Systemic / Q000150:complications / Q000235:genetics / Q000503:physiopathology*; D015398:Signal Transduction / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D020533:Angiogenesis Inhibitors; D007211:Indoles; D011758:Pyrroles; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; C116890:Semaxinib; D040262:Receptors, Vascular Endothelial Growth Factor; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II