Researchers at the University of Melbourne and Centre for Eye Research Australia have uncovered how retinal immune cells change during diabetes, which may lead to new treatments that can be used from an early stage of disease, before vision loss.
The group of 17 researchers, including from the Department of Optometry and Vision Sciences, found a specific type of immune cell, called microglia, contact both blood vessels and neurons in the retina and are able to change blood flow to meet the needs of neurons.
“Until recently, immune cells of the nervous system were thought to sit quietly, only responding when injury or disease occurred. Our finding expands our knowledge of what these cells do and shows a highly unusual mechanism by which blood vessels are regulated. This is the first time immune cells have been implicated in controlling blood vessel and blood flow,” co-author Professor Erica Fletcher said.
Fletcher and co-author Dr Andrew Jobling identified the chemical signal by which the immune cells communicate with blood vessels, and demonstrated that immune cell regulation of blood vessels is abnormal in diabetes.
The studies used preclinical animal models and a range of imaging methods that allowed researchers to see retinal immune cells in a living eye.
“We also isolated retinal immune cells from groups of normal and diabetic animals and analysed their genome to identify how these cells communicate with blood vessels,” Jobling said.
The research team used a range of pharmacological tools to examine how blood vessels change in response to activation of retinal immune cells.
Fletcher said the findings highlight a new way of controlling and potentially preventing retinal changes in diabetes.
“This finding also has implications for our understanding of other diseases of the retina and the brain. Although only at an early stage, these findings suggest a novel way for understanding vascular diseases of the brain with implications for our knowledge of stroke and Alzheimer’s disease,” she said.
She added: “Importantly, they were able to show that at an early stage of diabetes – before there are any visible changes at the back of the eye – blood vessels are abnormally narrow, affecting the way they supply the neurons of the retina. Retinal immune cells were implicated in this early vascular abnormality, implicating them as a novel therapeutic target for controlling early changes in the retina in diabetes.”
The study was published in PNAS, Proceedings of the National Academy of Sciences of the United States of America.