15 February 2020 by Bradley Wertheim

Endothelial c-terminal src kinase is associated with arteriolar fibrosis and impaired right ventricle-pulmonary artery coupling in early-stage pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by vascular fibrosis and right ventricular (RV) failure. The role of oxidant stress in advanced PAH is well-established; however, the pathogenetic implications of pro-fibrotic redox pathways in early-stage PAH are unknown. We hypothesized that unique redox-sensitive molecular targets in pulmonary artery endothelial cells (PAECs) distinguish early- from advanced-stage PAH. Sprague-Dawley rats were administered monocrotaline (MCT) (60 mg/kg) (day 0) and invasive hemodynamics, histopathology, and PAEC transcriptomics were analyzed on days 15 and 23 for early-stage and advanced PAH, respectively.

Compared to untreated control, early-stage PAH demonstrated impaired RV-PA coupling (1.13 ± 0.05 vs. 0.90 ± 0.06 Ees/Ea, P=0.02), increased indexed pulmonary vascular resistance (50 ± 8 vs. 213 ± 29 mmHg*min*g-1*mL-1, P<0.001), and a 2.7-fold increase in arteriolar collagen by picrosirius stain (P<0.0001) without substantial pulmonary hypertension (25 ± 1.2 vs. 33.2 ± 2.7 mmHg PA systolic pressure, P=0.02). The PAEC transcriptome in early-stage MCT-PAH included N=1,058 unique, differentially expressed genes (FDR<0.05), which was enriched for fibrosis genes (P=0.019). These data were used to develop a novel protein-protein interaction (PPI) network for predicting mediators of endothelial fibrosis in early-stage PAH. Dynamic network biomarker and gene ontology analyses suggested PPIs involving c-terminal src kinase (Csk) are important in early-stage PAH fibrosis in silico. Compared to control, Csk mRNA (log fold-change=+0.72; FDR<0.0001) and protein expression (123 ± 12 vs. 260 ± 25, a.u., P=0.01) were increased in PAECs in early-stage PAH by RNASEQ ex vivo and anti-Csk immunofluorescence in situ, respectively. Compared to control, hydrogen peroxide (250 μM) treatment increased PAEC Csk by 2.1-fold (P=0.02). Further, Csk correlated positively with arteriolar ollagen quantity in MCT-PAH (r=+0.87, P=0.006).

Collectively, early-stage PAH is defined by a unique endothelial pathobiology relative to advanced PAH. Redox-regulation of endothelial fibrosis by Csk may have important therapeutic implications for early-stage PAH.

About the author


profile picture of Bradley Wertheim

Bradley Wertheim

Fellow in pulmonary and critical care medicine

Brigham and Women's Hospital

United States

Key Contributors

Bradley M. Wertheim, Rui-sheng Wang, Ying-Yi Zhang, Andriy O. Samokhin, George A. Alba, Elena Arons, Paul B. Yu, and Bradley A. Maron Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA Channing Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, Department of Medicine, Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA Division of Cardiovascular Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA


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