The hepcidin-ferroportin axis influences mitochondrial function, proliferation, and migration in pulmonary artery endothelial and smooth muscle cells

Abstract

RationaleElevated circulating hepcidin levels have been reported in patients with pulmonary artery hypertension (PAH). Hepcidin has been shown to promote proliferation of human pulmonary artery smooth muscle cells (PASMCs) in vitro, suggesting a potential role in PAH pathogenesis. However, the role of human pulmonary artery endothelial cells (PAECs) as either a source of hepcidin, or the effect of hepcidin on PAECfunction has not previously been described. ObjectiveTo define the role of the hepcidin-ferroportin axis on the phenotype of pulmonary artery endothelial cells Methods and resultsPAECs treated with hepcidin, or IL-6 were investigated for both ferroportin and hepcidin release and regulation with immunofluorescence, mRNA levels and cellular release assays. Effects of hepcidin on PASMC and PAEC mitochondrial function was investigated using immunofluorescence and seahorse assay. Migration and proliferation of PASMC treated with conditioned media from hPAEC treated with hepcidin was investigated using the Xcelligence system and other tools. PAECs express ferroportin; hepcidin treatment of PAECs results in mitochondrial iron accumulation and intracellular hepcidin biosynthesis and release. Conditioned media from hepcidin treated PAECs causes PASMCs to down regulate ferroportin expression whilst promoting migration and proliferation. Inhibition of hepcidin in PAEC conditioned media limits these responses. PASMC cellular and mitochondrial iron retention are associated with migratory and proliferative responses. ConclusionsThe Hepcidin-ferroportin axis is present and operational in PAECs. Modulation of this axis shows distinct differences in responses seen between PAECS and PASMCs. Stimulation of this axis in PAECS with hepcidin may well institute proliferative and migratory responses in PASMCs of relevance to pathogenesis of PAH offering a potential therapeutic target.