Immune discovery points to therapies to improve stroke recovery

April 20, 2017
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

Deadly heart rhythm halted by noninvasive radiation therapy

December 13, 2017
Radiation therapy often is used to treat cancer patients. Now, doctors at Washington University School of Medicine in St. Louis have shown that radiation therapy—aimed directly at the heart—can be used to treat patients ...

Scientists rewrite our understanding of how arteries mend

December 13, 2017
Scientists from The University of Manchester have discovered how the severity of trauma to arterial blood vessels governs how the body repairs itself.

Ultra-thin tissue samples could help to understand and treat heart disease

December 12, 2017
A new method for preparing ultra-thin slices of heart tissue in the lab could help scientists to study how cells behave inside a beating heart.

Research reveals how diabetes in pregnancy affects baby's heart

December 12, 2017
Researchers at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA have discovered how high glucose levels—whether caused by diabetes or other factors—keep heart cells from maturing ...

Young diabetics could have seven times higher risk for sudden cardiac death

December 12, 2017
Young diabetics could have seven times more risk of dying from sudden cardiac arrest than their peers who don't have diabetes, according to new research.

Blood flow–sensing protein protects against atherosclerosis in mice

December 12, 2017
UCLA scientists have found that a protein known as NOTCH1 helps ward off inflammation in the walls of blood vessels, preventing atherosclerosis—the narrowing and hardening of arteries that can cause heart attacks and strokes. ...

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.