Tumor Necrosis Factor Induces Obliterative Pulmonary Vascular Disease in a Novel Model of Connective Tissue Disease-Associated Pulmonary Arterial Hypertension

Objective Connective tissue disease (CTD)-associated pulmonary arterial hypertension (PAH) is the second most common etiology ofPAHand carries a poor prognosis. Recently, it has been shown that female human tumor necrosis factor (TNF)-transgenic (Tg) mice die of cardiopulmonary disease by 6 months of age. This study was undertaken to characterize this pathophysiology and assess its potential as a novel model ofCTD-PAH. Methods Histologic analysis was performed onTNF-Tg and wild-type (WT) mice to characterize pulmonary vascular and right ventricular (RV) pathology (n = 40 [4-5 mice per group per time point]). Mice underwent right-sided heart catheterization (n = 29) and micro-computed tomographic angiography (n = 8) to assess vascular disease. Bone marrow chimeric mice (n = 12), and anti-TNF-treated mice versus placebo-treated mice (n = 12), were assessed.RNAsequencing was performed on mouse lung tissue (n = 6). Results TNF-Tg mice displayed a pulmonary vasculopathy marked by collagen deposition (P< 0.001) and vascular occlusion (P< 0.001) with associatedRVhypertrophy (P< 0.001) and severely increasedRVsystolic pressure (mean +/- SD75.1 +/- 19.3 mm Hg versus 26.7 +/- 1.7 mm Hg inWTanimals;P< 0.0001).TNF-Tg mice had increased alpha-smooth muscle actin (alpha-SMA) staining, which corresponded to proliferation and loss of von Willebrand factor (vWF)-positive endothelial cells (P< 0.01). There was an increase in alpha-SMA-positive,vWF-positive cells (P< 0.01), implicating endothelial-mesenchymal transition. Bone marrow chimera experiments revealed that mesenchymal but not bone marrow-derived cells are necessary to drive this process. Treatment with anti-TNFtherapy halted the progression of disease. This pathology closely mimics humanCTD-PAH, in which patient lungs demonstrate increasedTNFsignaling and significant similarities in genomic pathway dysregulation. Conclusion TheTNF-Tg mouse represents a novel model ofCTD-PAH, recapitulates key disease features, and can serve as a valuable tool for discovery and assessment of therapeutics.