A particular combination of bacteria in the gut could worsen symptoms of multiple sclerosis (MS), research suggests.
Researchers at the RIKEN Center for Integrative Medical Sciences in Japan have found that two specific gut bacteria enhance the activity of immune cells that attack the body’s own brain and spinal cord.
MS is characterised by the immune system attacking the myelin that covers the nerve cells of the brain and spinal cord in a process called demyelination. This process affects how the communication between neurons and with muscles, which causes the symptoms associated with the disease.
Research has previously found that bacteria in the gut could affect MS symptoms, but how this occurs is unknown.
Researchers gave mice, who experienced similar process of the spinal cord that results from autoimmune attacks in MS, the antibiotic ampicillin, and found that this reduced demyelination.
When the mice were given ampicillin, it reduced the activity of T cells, which attack the protein that helps myelin stick to neurons.
Researcher Hiroshi Ohno, who led the study, published in the journal Nature, says, “We found that treatment with ampicillin, and only ampicillin, selectively reduced activity of T cells that attack an important protein called myelin oligodendrocyte glycoprotein (MOG), which helps myelin stick to neurons.”
The researchers confirmed this by taking immune cells from the small intestines and other regions and measuring their cytokine production in the presence of MOG. Production was reduced by ampicillin when the T cells came from the small intestine.
This means bacteria in the small intestine activated MOG-specific T cells, which can attack myelin. To figure out which bacteria this was, exactly, the researchers looked at the microbiota that were almost completely eradicated in the mice who were given ampicillin.
The researchers found a new bacteria, OTU002, and confirmed it was the one responsible for the worsening symptoms – but only when it reacted with another microorganism and mimicked the location on MOG that the T cells recognise.
They found that a protein expressed by Lactobacillus reuteri activated MOG-specific T cells.
The researchers say their study gives hope to people looking for effective treatments for MS, but says further research is needed using humans.
