Chronic Activation of the Renin-Angiotensin System Induces Lung Fibrosis.
Pulmonary fibrosis is a serious lung disorder that can lead to respiratory failure. Here we show that transgenic mice expressing active renin from the liver (RenTgMK) developed progressive pulmonary fibrosis leading to impaired pulmonary function. Histological analyses revealed a marked increase in extracellular matrix (ECM) deposition and decrease in alveolar size in the lungs of RenTgMK mice compared to wild-type (WT) littermates, accompanied with increased expression of ECM proteins and fibrogenic factors. The increase in lung fibrosis led to a substantial decrease in respiratory system compliance. Two-week treatment with aliskiren (renin inhibitor) or losartan (AT1 antagonist) ameliorated pulmonary ECM deposition, blocked the induction of ECM proteins and fibrogenic factors and improved respiratory compliance in RenTgMK mice, confirming a critical role of the renin-Ang II-AT1 cascade in promoting pulmonary fibrogenesis. However, when RenTgMK mice were treated with hydralazine (a smooth muscle relaxant), the blood pressure was normalized but the lung fibrotic abnormalities, fibrogenic gene induction and pulmonary elasticity were not corrected. Moreover, intratracheal instillation of lipopolysaccharide induced more severe lung injury in RenTgMK mice compared to WT littermates. These observations demonstrate that the renin-angiotensin system is a key mediator of lung fibrosis, and its pro-fibrotic effect is independent of blood pressure.
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.|Division of Cardiology, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning, 110001, China.
Jiaolong
J
Wang
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.|Division of Endocrinology, Shengjing Hospital, China Medical University, Shenyang, Liaoning, 110004, China.
Li
L
Chen
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.
Bohao
B
Chen
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.
Angelo
A
Meliton
Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA.
Shu Q
SQ
Liu
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.|Division of Neonatology, Shengjing Hospital, China Medical University, Shenyang, Liaoning, 110004, China.
Yongyan
Y
Shi
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.|Division of Neonatology, Shengjing Hospital, China Medical University, Shenyang, Liaoning, 110004, China.
Tianjing
T
Liu
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.
Dilip K
DK
Deb
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.
Julian
J
Solway
Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.
Yan Chun
YC
Li
D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D018450:Disease Progression; D006973:Hypertension / Q000150:complications; D051379:Mice; D008822:Mice, Transgenic; D011658:Pulmonary Fibrosis / Q000150:complications / Q000503:physiopathology*; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism*; D012084:Renin-Angiotensin System
D044139:Receptor, Angiotensin, Type 2; D000804:Angiotensin II