Objective Systemic sclerosis-associated pulmonary arterial hypertension differs from idiopathic pulmonary arterial hypertension with respect to histopathology, treatment responses and survival. Medical progress on PAH is hampered by the lack of human biosamples and suitable animal models. In this study, the authors evaluated fos-related antigen 2 (Fra-2) transgenic mice as a novel model for systemic sclerosis-associated pulmonary arterial hypertension.
Methods Lung sections of Fra-2 transgenic (n=12) and wild-type mice (n=6) were analysed at 16 weeks by histology using Dana Point criteria. Cellular and molecular key players were assessed by immunohistochemistry. To test the model's sensitivity to change over treatment, a subgroup of Fra-2 transgenic mice (n=6) was treated with the tyrosine kinase inhibitor nilotinib twice daily 37.5 mg orally from 8 weeks of age.
Results Fra-2 transgenic mice developed severe vascular remodelling of pulmonary arteries and non-specific interstitial pneumonia-like interstitial lung disease resembling human systemic sclerosis-associated pulmonary hypertension. Histological features typical for systemic sclerosis-associated pulmonary arterial hypertension, such as intimal thickening with concentric laminar lesions, medial hypertrophy, perivascular inflammatory infiltrates, adventitial fibrosis, but not pulmonary occlusive venopathy were frequently detected. Platelet-derived growth factor signalling pathways were activated in pulmonary vessels of Fra-2 transgenic compared with wild-type mice. Since treatment with nilotinib strongly prevented the development of proliferative vasculopathy and lung fibrosis, the model proved to be sensitive to treatment.
Conclusions This study suggests that Fra-2 transgenic mice as an animal model of systemic sclerosis-associated pulmonary arterial hypertension display main characteristic features of the human disease. It therefore allows studying pathophysiological aspects and might serve as a preclinical model for interventional proof-of-concept studies.
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Funding BM received the Encysive Young Investigators Award; AJ received the IAR-EPALINGES and FP7 EU Masterswitch grant; SG received the FP7 EU Masterswitch grant; and JHW received the Distler IZKF and DFG grant.
Competing interests JHWD has consultancy relationships and/or has received research funding from Boehringer Ingelheim, Celgene, Bayer Pharma, Actelion, Pfizer, Ergonex, BMS, JB Therapeutics, Anaphore, Inc, Sanofi-Aventis, Novartis, Array Biopharma and Active Biotec in the area of potential treatments of scleroderma and is stock owner of 4D Science. OD has consultancy relationship and/or has received research funding from Actelion, Pfizer, Ergonex, BMS, Sanofi-Aventis, United BioSource Corporation, medac in the area of potential treatments of scleroderma and its complications. He has received lecture honoraria from Actelion, Pfizer, Encysive and Ergonex. The real or perceived potential conflicts listed above are accurately stated. All others were supported by their respective institutions.
Provenance and peer review Not commissioned; externally peer reviewed.