Activated Immune System Attacks Brain

The study by researchers from the University of Manchester suggests a way in which an immune system that has already been activated by an infection elsewhere in the body can target the vulnerability of the brain following a stroke.

The team’s findings may have important implications for the elderly, who are most at risk of stroke and frequently suffer from infection and other conditions, such as atherosclerosis, that stimulate the immune system.

“Tests on mice given a stimulus to mimic bacterial infection and activate their immune system showed they suffered more than twice the amount of cell death in the brain following a stroke compared to mice that were given a placebo. The study’s findings are particularly significant because a recent study has shown that the chances of having a stroke are increased after infection. However, it will be important to confirm these results in further studies,” said Dr Barry McColl, who is based in Manchester’s Faculty of Life Sciences.

The group also discovered that a population of white blood cells, called neutrophils, that normally fight infection by killing bacteria, was responsible for the increased brain damage. Mice in which neutrophils were depleted did not develop as much damage. The results indicate that other conditions, like obesity and tooth decay, which trigger similar immune responses to infections, might also increase the severity of brain damage caused by stroke.

“Knowing exactly how the underlying activation status of the immune system affects stroke will help to develop new ways of combating the damage caused by stroke,” said Dr McColl. “This could have serious implications for the way stroke patients are treated in the future. For example, anti-inflammatory drugs that are currently being tested in human trials may be able to dampen the activated immune system and so reduce brain damage.”

MEDICA.de; Source: LifeSciences 2007