Specialized immune cells called eosinophils are prevalent in the fatty tissue that surrounds blood vessels and helps them operate normally. Now a group of British researchers has discovered that these cells are greatly diminished in obesity—and that their absence contributes to Type 2 diabetes and hypertension.
The findings, published in the journal Scientific Reports, were made by scientists from the University of Manchester, Lund University and the University of Salford, who worked with mouse models of obesity. They discovered that eosinophils govern the release of two substances that are vital to the healthy functioning of fat surrounding blood vessels: nitric oxide and adiponectin, a protein, according to a press release. So when the immune cells disappear, high blood pressure and other disorders develop.
The researchers also demonstrated that if they added back eosinophils, they could restore blood vessels back to a healthy state. The cells "seem to be incredibly important in a number of processes and this presents us with an exciting new area to investigate for a whole range of illnesses," said Sheena Cruickshank, Ph.D., senior lecturer at the University of Manchester and the lead author, in the release.
Eosinophils, in fact, are already a hot target in medicine—but most efforts so far have been aimed at inhibiting them, not replacing them. Eosinophils exacerbate some forms of asthma, giving rise to a whole new class of drugs that relieve symptoms by inhibiting the immune cells. Glaxo’s Nucala was the first drug in the class. Now AstraZeneca is gearing up to apply for FDA approval of its anti-eosinophil treatment benralizumab. Analysts have blockbuster hopes for both drugs.
Scientists on the British team are suggesting a whole new role for eosinophils based on their mouse study. They were particularly encouraged by how quickly the immune cells acted to restore normal functioning to fat surrounding blood vessels, which is known as perivascular adipose tissue (PVAT). They believe that this understanding of the role of eosinophils will open up new treatment options for Type 2 diabetes and hypertension.
"This type of immune cell is present in many parts of the body and was once thought to just act in parasitic infections and allergies,” Cruickshank said, "but it's fast becoming clear that they have a significant effect on lots of aspects of health and immunity."