S99 Hepcidin down regulates BMPRII in pulmonary artery endothelial cells mimicking pulmonary artery hypertension phenotypes

Introduction

Pulmonary arterial hypertension (PAH) is characterised by vascular remodelling of pulmonary arterioles. Disrupted iron homeostasis linked to elevated hepcidin levels has been observed in PAH patients, and disruption of the hepcidin/ferroportin axis at the level of the pulmonary vasculature cells has been shown to contribute to proliferation of pulmonary artery smooth muscle cells. A role for Pulmonary artery endothelial cells (PAECs) linked to hepcidin has not been investigated.

Objectives

In this study we explored the influences of hepcidin-25 on PAEC gene expression targeting BMPRII, known to be dysfunctional in PAH.

Methods

Cells were challenged with Hepcidin-25 (1 μg/mL) or for comparison IL-6 (10 ng/mL). Transcriptional regulation was analysed by RT-PCR, protein expression by immunocytochemistry.

Results

Novel findings demonstrate that BMPRII mRNA expression is significantly down regulated in PAECs challenged with hepcidin-25 over a time course from 1 hour to 5 hours; figure 1 illustrates findings at 3 hours. IL-6 challenge was not able to replicate this response over the same time frame. In addition, Western blot analysis of cell lysates (n=2) showed an obvious loss of BMPRII protein expression in Hepcidin-25 challenged cells when compared to control and IL-6 challenged cell lysates.

Conclusion

This is the first report linking hepcidin-25 activity to potentially dysfunctional BMPRII responses in PAECs. Given the established role of hepcidin as regulator of cellular iron levels, a role for downstream signaling linked to iron accumulation in PAECs may offer a plausible mechanism for these observations and warrants further investigation. These studies may provide novel insights regarding emerging concepts of hepcidin driven proliferative and second messenger responses of relevance to PAH.