An endothelial activin A-bone morphogenetic protein receptor type 2 link is overdriven in pulmonary hypertension

Pulmonary arterial hypertension is a progressive fatal disease that is characterized by pathological pulmonary artery remodeling, in which endothelial cell dysfunction is critically involved. We herein describe a previously unknown role of endothelial angiocrine in pulmonary hypertension. By searching for genes highly expressed in lung microvascular endothelial cells, we identify inhibin-β-A as an angiocrine factor produced by pulmonary capillaries. We find that excess production of inhibin-β-A by endothelial cells impairs the endothelial function in an autocrine manner by functioning as activin-A. Mechanistically, activin-A induces bone morphogenetic protein receptor type 2 internalization and targeting to lysosomes for degradation, resulting in the signal deficiency in endothelial cells. Of note, endothelial cells isolated from the lung of patients with idiopathic pulmonary arterial hypertension show higher inhibin-β-A expression and produce more activin-A compared to endothelial cells isolated from the lung of normal control subjects. When endothelial activin-A-bone morphogenetic protein receptor type 2 link is overdriven in mice, hypoxia-induced pulmonary hypertension was exacerbated, whereas conditional knockout of inhibin-β-A in endothelial cells prevents the progression of pulmonary hypertension. These data collectively indicate a critical role for the dysregulated endothelial activin-A-bone morphogenetic protein receptor type 2 link in the progression of pulmonary hypertension, and thus endothelial inhibin-β-A/activin-A might be a potential pharmacotherapeutic target for the treatment of pulmonary arterial hypertension.


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Koji Ikeda
No software was used.
Statistical analysis was performed using the GraphPad 8.0 software.
The authors declare that all data supporting the findings of this study are available within the paper and its supplementary information files. Authentication www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE156233). All remaining data will be available from the corresponding author upon reasonable request.
We did not statistically determine the sample size, but common sample size for each group for this type of experimental work in literature was chosen. Basically, more than three cells/samples were used for in vitro experiments, while more than five animals/samples were used for in vivo experiments.
We did not exclude any data from the analysis.
For all the data, experiments were replicated for 2-3 independent times.
We used randomization whenever possible. Specifically, we randomly determined the allocation of animals (normoxia or hypoxia) and allocation of cells (GFP-transfection or INHBA-transfection; vehicle group or Activin A group; vehicle group or Follistatin group; vehicle group or BMP-4 group or Activin A group; vehicle group or Bafilomycin group; vehicle group or PitStop group; etc.). Also, we captured images of lung histologies at randomly chosen fields.
Because single researcher (GRTR) has performed the majority of experiments, investigators were not blinded to sample allocation during experiments and outcome assessment. However, most of data are objective and there is no room for biased evaluation. Also, efforts to avoid biased evaluation were made by using multiple biologically independent samples as well as by choosing multiple ROI for data acquisition.