Intestinal microbes protect against neurological damage due to viral infections

Intestinal microbes produce compounds that induce immune cells to destroy harmful viruses in the brain and nervous system, according to a study in mice published today in the United States. eLife.

The results suggest that having a healthy and diverse microbiota is essential for rapidly eliminating viruses from the nervous system to prevent paralysis and other risks badociated with diseases such as multiple sclerosis.

A disease that causes progressive damage to nerve cells, multiple sclerosis has become more common in recent decades. Viral infections in the brain or spinal cord are at the root of this disease. Some scientists believe that changes in the way we eat, increased sanitation, or increased use of antibiotics can be harmful to the helpful bacteria that live in the human body, potentially increasing the risk of multiple sclerosis and multiple sclerosis. other related diseases.

"We wanted to determine whether intestinal microbes could alter the immune response to central nervous system virus and whether it affected the magnitude of the damage caused by the virus," said one of the lead authors, David Garrett Brown , graduate research badistant at the Department of Pathology of the University of Utah Health, Salt Lake City, United States.

To do this, Garrett Brown and his co-lead author Ray Soto examined the effect of the mouse hepatitis virus, a virus that infects the nervous system cells of the mouse and causes symptoms of Multiple sclerosis type, on two groups of mice: some with normal gut microbes and some that were free of bacteria. They found that bacteria-free mice had a weak immune response, were unable to eliminate the virus and developed more severe paralysis, while those with normal intestinal bacteria were better able to fight the virus. .

Mice treated with antibiotics before the onset of the disease were unable to defend themselves. They also had fewer immune cells called microglia, which help to signal viruses to destruction by other immune cells.

The team then identified compounds produced by intestinal bacteria that could help microglia. When they administered these compounds to mice without bacteria, they found that the animals were protected from the neurological damage caused by the virus.

"We showed that intestinal microbes protected infected mice from paralysis by activating a specific pathway in the cells of the central nervous system," says June Round, badociate professor in the Department of Pathology at the University of Toronto. Utah Health and co-author Professor Thomas Lane, from the same department. "This suggests that signals from microbes are essential for rapidly eliminating viruses in the nervous system and preventing the damage caused by many diseases similar to multiple sclerosis." Our results underscore the importance of maintaining a diverse community of bacteria. in the intestines, as well as interventions aimed at restoring this community after taking antibiotics may be necessary. "