Immune cells linked to high blood pressure

Scientists have pinpointed cells in the immune system that could be key to tackling high blood pressure. The findings also shed light on current treatments that could increase risk of the disorder, which affects more than 12 million people in the UK.

Heart attacks

High blood pressure – or hypertension – is a leading cause of life-threatening conditions including heart attack, kidney disease and stroke. The study revealed a new role for specialised white blood cells – known as macrophages – that are central to the body’s immune system.

Scavenger cells

Researchers led by the University of Edinburgh discovered that macrophages scavenge for and ‘eat’ molecules of a powerful hormone known as endothelin. By monitoring and regulating endothelin levels in the blood, these white blood cells help blood vessels relax, significantly lowering blood pressure.

Salt diet

The scientists found that lowering levels of macrophages increased blood pressure in mice fed a high salt diet. When the macrophage level returned to normal, blood pressure also normalised. The same findings were replicated in mice genetically bred with a deficiency of the endothelin system and in mice with drug-induced high blood pressure.

Medications

The researchers then looked at white blood cells in patients taking medication for an immune system disorder that attacks blood vessels. Those taking medication known to reduce macrophages had higher blood pressure compared with patients taking other medications.

Therapy improvements

Scientists say these findings could help spot people most at risk of developing hypertension. The findings could open avenues to improve current therapies, although researchers caution that further human studies are needed. The study, published in the European Heart Journal, was funded by the British Heart Foundation and Kidney Research UK.

“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, University of Edinburgh