Infection hinders blood vessel repair following traumatic brain or cerebrovascular injuries

Thursday, September 23, 2021

NIH study in mice demonstrates the importance of quickly addressing infection

Traumatic brain injury (TBI) and other injuries to blood vessels in the brain, like stroke, are a leading cause of long-term disability or death. Researchers at the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health, have found a possible explanation for why some patients recover much more poorly from brain injury if they later become infected. The findings were published in Nature Immunology.

Making use of a mouse model for mild TBI (mTBI) that they had developed previously, the team of researchers led by NINDS scientist Dorian McGavern, Ph.D., discovered that viral, fungal, or a mimic for bacterial infections all impacted blood vessel repair within the meninges, the protective covering of the brain. When they looked closer, they observed that some cells of the immune system no longer moved into the site of the injury, which occurred in the uninfected animals, suggesting they were responding to systemic infection. The study also looked in a second injury model affecting the blood vessels in the brain, called a cerebrovascular injury (CVI), and saw a similar effect on repair.

“Evolution prioritizes mobilizing the immune system to fight off infection over repair,” said Dr. McGavern. “Because the body is dealing with a greater threat, cells that would normally repair the damaged blood vessels in or around the brain are needed elsewhere.”

Seven days after mTBI, the blood vessels (stained in red) in the tissues around the brain are not completely repaired. A marker for intact vessels was used (labeled in green) to distinguish fully functional blood vessels (yellow) from ones that are still damaged (red).