10 Jun 2014

Scientists find new molecule that contributes to brain disease

Figure1. Healthy tissue showing cells closely packed together

Figure1. Healthy tissue showing cells closely packed together

A tiny molecule has been found responsible for causing ‘leakiness’ of the brain’s blood vessels. This leakiness allows the uncontrolled flow of toxins and other molecules into the brain leading to nerve cell damage – a symptom of neurological diseases such as multiple sclerosis (MS).

Figure2. Tissue showing gaps between cells due to miR-155

Figure2. Tissue showing gaps between cells due to miR-155

The study, led by Dr Ignacio Romero from The Open University (OU) with support from researchers at Sheffield, London and Amsterdam, focuses on how inflammation changes the function of blood vessels in the brain. Researchers found that the cells which line the blood vessels and control the access of molecules and immune cells to the brain become leaky when inflamed due to neurological immune conditions. This inflammation is a characteristic of a number of such conditions from autoimmune diseases such as MS to brain infections such as in HIV dementia and even in bacterial infections of the blood.

In healthy people these tissue cells are tightly joined together creating a strong barrier which prevents molecules from passing through into the brain from the blood stream. Researchers found that during inflammation levels of the molecule ‘microRNA-155’ (miR-155) increase inside these barrier cells creating microscopic gaps that let blood-borne material such as toxins through.

Up until now scientists have not known exactly how inflammation in the brain weakens the barrier of blood vessels. This discovery could have significant implications in the treatment of patients with neurological diseases other than MS including, amongst others, Alzheimer’s, and brain and spinal cord bacterial and viral infections such as HIV and meningitis. Further understanding of how this leakage occurs could be used to develop drugs to protect a patient’s brain, helping to reduce the severity of these diseases.

Dr Ignacio Romero, Senior Lecturer in Cellular Neuroscience at the OU’s Department of Life, Health and Chemical Sciences said:
"This research has helped us to gain a better understanding of how toxins and other blood-borne molecules are leaked into the brain in inflammatory conditions. This is crucial, not only for helping to explain the molecular underpinnings of neurological diseases such as Alzheimer’s and Multiple Sclerosis, but also for opening up new possibilities for developing treatments to reduce the flow of these unwanted molecules to the brain and also for delivering life-saving drugs.”

Notes to editors

To find out more about this research, please visit our research website:

To read the paper MicroRNA-155 negatively affects blood–brain barrier function during neuroinflammation in full, please visit:

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