Loss of Amphiregulin drives inflammation and endothelial apoptosis in pulmonary hypertension.

Pulmonary hypertension (PH) is a vascular disease characterized by elevated pulmonary arterial pressure, leading to right ventricular failure and death. Pathogenic features of PH include endothelial apoptosis and vascular inflammation, which drive vascular remodeling and increased pulmonary arterial pressure. Re-analysis of the whole transcriptome sequencing comparing human pulmonary arterial endothelial cells (PAECs) isolated from PH and control patients identified AREG , which encodes Amphiregulin, as a key endothelial survival factor. PAECs from PH patients and mice exhibited down-regulation of AREG and its receptor epidermal growth factor receptor (EGFR). Moreover, the deficiency of AREG and EGFR in ECs in vivo and in vitro heightened inflammatory leukocyte recruitment, cytokine production, and endothelial apoptosis, as well as diminished angiogenesis. Correspondingly, hypoxic mice lacking Egfr in ECs ( cdh5 cre/+ Egfr fl/fl ) displayed elevated RVSP and pulmonary remodeling. Computational analysis identified NCOA6 , PHB2 , and RRP1B as putative genes regulating AREG in endothelial cells. The master transcription factor of hypoxia HIF-1⍺ binds to the promoter regions of these genes and up-regulates their expression in hypoxia. Silencing of these genes in cultured PAECs decreased inflammation and apoptosis, and increased angiogenesis in hypoxic conditions. Our pathway analysis and gene silencing experiments revealed that BCL2-associated agonist of cell death (BAD) is a downstream mediator of AREG BAD silencing in ECs lacking AREG mitigated inflammation and apoptosis, and suppressed tube formation. In conclusion, loss of Amphiregulin and its receptor EGFR in PH is a crucial step in the pathogenesis of PH, promoting pulmonary endothelial cell death, influx of inflammatory myeloid cells, and vascular remodeling.