Immune discovery points to therapies to improve stroke recovery

April 20, 2017, University of Edinburgh
A blood clot forming in the carotid artery. Credit: copyright American Heart Association

Having a stroke damages immune cells as well as affecting the brain, research has found.

The findings help explain why patients have a greater risk of catching life-threatening infections, such as pneumonia, after having a .

Therapies that boost survival of the affected immune cells or compensate for their damage could help improve the recovery of , the researchers say.

The study found that patients have reduced levels of protective antibodies in their blood after having a stroke, which might explain why they are more susceptible to infections.

Tests with mice revealed those which experienced a stroke had fewer numbers of specialised called marginal zone B cells, which produce antibodies.

Affected mice were more susceptible to bacterial lung infections, the researchers found.

Loss of the B cells was caused by a chemical called noradrenaline produced by nerves activated during stroke.

Researchers, led by the University of Edinburgh's Roslin Institute, found they could protect the mice from infections using a therapy to block the effects of noradrenaline.

Noradrenaline is part of the body's fight or flight response. It helps to prepare the body for action and has a range of effects, such as raising heart rate, boosting blood supply and triggering the release of energy from stores.

Blocking noradrenaline would probably be too dangerous in stroke patients, the researchers caution. They say development of other therapies that block or bypass the damage to the immune system could offer new approaches to help cut the risk of after stroke.

The study could also lead to new tests to identify which stroke patients have the highest chances of developing an infection, so that they can be monitored more closely.

Around one-third of stroke patients are stricken by infections, which can lessen their chances of making a good recovery. Treatment with antibiotics does not protect patients from developing infections and new therapies are urgently needed.

The research is published in the journal Nature Communications and was funded by the Biotechnology and Biological Sciences Research Council and the Medical Research Council. The Roslin Institute receives strategic funding from the BBSRC.

Experts from The University of Manchester and Salford Royal NHS Foundation Trust also contributed to the research.

Dr Barry McColl, of The Roslin Institute at the University of Edinburgh, said: "Our work shows that stroke has damaging effects on the normal ability of the immune system to protect us from infections such as pneumonia, which are particularly life-threatening in stroke patients. This could partly explain why people who have strokes are so prone to getting infections.

"We now plan to build on our findings by developing and testing new treatments that can block or bypass these immune deficits with B a particular target"

Professor Craig Smith, on behalf of the stroke research group at Salford Royal NHS Foundation Trust, said: "Infections are a major complication of stroke and lead to a worse outcome for . This is an important study which provides new insights about how stroke affects the immune system, which we hope will lead to new approaches to preventing infections after stroke."

Explore further: Infection is an important post-stroke problem

More information: Laura McCulloch et al, Adrenergic-mediated loss of splenic marginal zone B cells contributes to infection susceptibility after stroke, Nature Communications (2017). DOI: 10.1038/NCOMMS15051

Related Stories

Infection is an important post-stroke problem

October 26, 2011
After a stroke the brain tries to protect itself by blocking all inflammation. However, this also makes the patient highly susceptible to infection which can lead to death. Researchers have now discovered the mechanism behind ...

Immune cell study prompts rethink on how to tackle infections

February 14, 2017
Fresh insights into how immune cells are regulated could signal a new approach to tackling infections.

Early intervention in brain inflammatory pathways may improve stroke recovery

November 28, 2016
Intracerebral hemorrhage is a type of stroke characterized by the rupture of a blood vessel within the brain. When the brain is exposed to blood, local immune cells become activated, triggering inflammation that promotes ...

Outcome of stroke worse for people with infection

April 15, 2014
(Medical Xpress)—A team of scientists at the University of Manchester has now found a key to why and how infection is such a bad thing for stroke sufferers

Statin drugs reduce infection risk in stroke patients

June 16, 2016
A Washington State University researcher has found that statin drugs can dramatically lower the risk of infections in stroke patients.

Recommended for you

Infections could trigger stroke in pregnant women during hospital delivery

April 20, 2018
Pregnant women who have an infection when they enter the hospital for delivery might be at higher risk of having a stroke during their stay, according to new research.

Compound improves stroke outcome by reducing lingering inflammation

April 20, 2018
An experimental compound appears to improve stroke outcome by reducing the destructive inflammation that can continue months after a stroke, scientists report.

Novel antioxidant makes old blood vessels seem young again

April 19, 2018
Older adults who take a novel antioxidant that specifically targets cellular powerhouses, or mitochondria, see age-related vascular changes reverse by the equivalent of 15 to 20 years within six weeks, according to new University ...

Changing how blood pressure is measured will save lives

April 19, 2018
Traditional methods of testing for high-blood pressure are no longer adequate and risk missing vital health signs, which can lead to premature death, a study co-led by UCL has found.

Eyes of adolescents could reveal risk of cardiovascular disease

April 19, 2018
New research has found that poorer well-being or 'health-related quality of life' (HRQoL) in adolescence could be an indicator of future cardiovascular disease risk.

Obesity linked with higher chance of developing rapid, irregular heart rate

April 18, 2018
People with obesity are more likely to develop a rapid and irregular heart rate, called atrial fibrillation, which can lead to stroke, heart failure and other complications, according to Penn State researchers.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.