Immune cells may be the key to tackling high blood pressure

A CVS study led by Dr Neeraj Dhaun and Professor Matthew Bailey revealed a new relationship between the immune system, blood pressure, and blood vessels.

A diagram explaining the vascular endothelial system and macrophage ET-1 clearance
Macrophage-endothelin system interplay

Scientists have discovered new links between white blood cells and blood pressure, offering hope to those suffering from hypertension.

The study, led by a team at the BHF University of Edinburgh Centre for Cardiovascular Science (CVS), also revealed that current treatments could increase risk of the disorder.

Hypertension, or high blood pressure, affects more than 12 million people in the UK and is the leading cause of life-threatening conditions like heart attack, kidney disease, and stroke.

The findings of this study uncovered a new function of specialised white blood cells—known as macrophages—in the immune system. CVS researchers showed, for the first time, that macrophages play a role in regulating blood pressure.

The researchers, led by Dr Neeraj Dhaun and Professor Matthew Bailey, studied the levels of endothelin—a powerful hormone found in the blood—in mice models. They showed that macrophages ‘eat’ molecules of this hormone in the blood, which relaxes blood vessels and, in turn, lowers blood pressure.

While studying mice fed with a high salt diet, the scientists observed that lowering levels of macrophages led to increased blood pressure. However, blood pressure returned to normal after bringing the macrophages back up to a normal level.

They found similar results while observing mice genetically bred with a deficiency of the endothelin system and mice with drug-induced high blood pressure.

From there, the CVS researchers examined the white blood cells in patients taking medication for immune disorders that attack blood vessels. Patients taking medication known to lower macrophage levels had higher blood pressure than patients taking other medications.

The results of this study identify those who may be at higher risk of developing hypertension. The novel findings could also eventually lead to improved drug treatment and therapies for hypertension patients.

The study, published in the European Heart Journal, was funded by the British Heart Foundation.

Hypertension affects millions of people across the globe, including 70 per cent of people over 70.

Our discovery sheds light on risk factors, and crucially, opens routes to investigate new drugs that could help patients. Our next steps will be to investigate the role of macrophages in people living with hypertension.

Professor Matthew Bailey
Chair in Renal Physiology at CVS, who co-led the study

In the UK, an estimated 6.8 million people are living with undiagnosed high blood pressure. This causes damage to the heart and blood vessels, putting you at risk of a potentially fatal heart attack or stroke. But we still don’t fully understand all the mechanisms that lead to high blood pressure.

This study shows for the first time that macrophages – a type of cell that helps regulate our immune responses – can be involved in the control of blood pressure. More research is needed but these cells could be a new target for drugs to treat the condition.

Jeremy Pearson
Associate Medical Director at The British Heart Foundation


Original paper: A novel role for myeloid endothelin-B receptors in hypertension”, by Alicja Czopek et al. European Heart Journal. doi:10.1093/eurheartj/ehy881

Published 17 January 2019.

Link to original paper