Journal
AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY
Volume 316, Issue 6, Pages L1150-L1164Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajplung.00302.2018
Keywords
oxidant stress; pulmonary hypertension; sickle cell disease; thrombospondin-1; transgenic mouse models
Categories
Funding
- American Society of Hematology Scholar Award
- Gilead Sciences Research Scholars Program in Pulmonary Arterial Hypertension
- National Heart, Lung, and Blood Institute [1K23 HL-112848-01A1, 2R01 HL-098032, 1R01 HL-125886, 5P01 HL-103455, T32 HL-110849]
- Institute for Transfusion Medicine
- Hemophilia Center of Western Pennsylvania, Pittsburgh, PA
- Heart, Lung, Blood, and Vascular Medicine Institute of the University of Pittsburgh
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Pulmonary hypertension (PH) is a leading cause of death in sickle cell disease (SCD) patients. Hemolysis and oxidative stress contribute to SCD-associated PH. We have reported that the protein thmmbospondin-1 (TSP1) is elevated in the plasma of patients with SCD and, by interacting with its receptor CD47, limits vasodilation of distal pulmonary arteries ex vivo. We hypothesized that the TSP1-C])47 interaction may promote PH in SCD. We found that TSP1 and CD47 are upregulated in the lungs of Berkeley (BERK) sickling (Sickle) mice and patients with SCD-associated PH. We then generated chimeric animals by transplanting BERK bone marrow into C57BL/6J (n = 24) and CD47 knockout (CD47KO, n = 27) mice. Right ventricular (RV) pressure was lower in fully engrafted Sickle-to-CD47KO than Sickle-to-C57BL/6J chimeras, as shown by the reduced maximum RV pressure (P = 0.013) and mean pulmonary artery pressure (P = 0.020). The afterload of the sickle-to-CD47KO chimeras was also lower, as shown by the diminished pulmonary vascular resistance (P = 0.024) and RV effective arterial elastance (P = 0.052). On myography, aortic segments from Sickle-to-CD47KO chimeras showed improved relaxation to acetylcholine. We hypothesized that, in SCD, TSP1-CD47 signaling promotes PH, in part, by increasing reactive oxygen species (ROS) generation. In human pulmonary artery endothelial cells, treatment with TSPI stimulated ROS generation, which was abrogated by CD47 blockade. Explanted lungs of CD47KO chimeras had less vascular congestion and a smaller oxidative footprint. Our results show that genetic absence of CD47 ameliorates SCD-associated PH, which may be due to decreased ROS levels. Modulation of TSP1-CD47 may provide a new molecular approach to the treatment of SCD-associated PH.
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