A recent study, published in the journal Scientific Reports, found that reduction of the number of immune cells in the fatty tissue cause diabetes and hypertension in the overweight people.
Researchers from the University of Manchester, Lund University and the University of Salford together investigated a type of immune cell called - eosinophils -present in a layer of fat tissue called the perivascular adipose tissue (PVAT), which surrounds blood vessels and helps to maintain normal blood vessel function by reducing artery contraction. The study found that eosinophils were considerably reduced in the PVAT in obesity in mice and that the PVAT function was severely impaired, contributing to 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, but it's fast becoming clear that they have a significant effect on lots of aspects of health and immunity," said lead researcher of the study Dr Sheena Cruickshank on the Wellcome Trust-funded study.
"Our study showed that in fact the secretions from eosinophils have a profound effect on how the blood vessels operate and when they are missing, as in obesity, serious health problems can start to develop," Cruickshank added.
The role of the eosinophils also opens up new opportunities to investigate treatments for Type-2 diabetes and hypertension. PVAT from fat that lack eosinophils could quickly be rescued by addition of eosinophils, demonstrating that there is the potential for a treatment based on restoring this function.
The researchers observed that eosinophils influenced the release of nitric oxide and a protein called adiponectin, which control healthy PVAT function. This appears to be a unique function of these immune cells. The researchers are particularly excited by how quickly the eosinophils could restore PVAT function, showing just how potent they may be.
"These immune cells have been traditionally overlooked but this study shows for the first time that they have a direct role to play in processes in the body beyond the immune system," Dr Cruickshank added.