• Researchers say they are learning more about how gut bacteria can be used to treat autoimmune diseases.
• In a study involving mice, researchers say they have developed a probiotic that could be a treatment for multiple sclerosis.
• Experts say the probiotic would work in the same general way as diets do to control inflammation but may have longer-lasting effects.

Gut bacteria have been shown to be vitally important to overall health.

Now, a new study reports that these microbes also could play a role in treating autoimmune diseases such as multiple sclerosis (MS).

Researchers at Boston’s Brigham and Women’s Hospital say they have bioengineered a probiotic that effectively suppresses autoimmunity in the brain, at least in animal studies.

The research, published in the journal Nature, suggests that probiotic therapy could be used to treat MS and other autoimmune diseases where the immune system dysfunctionally attacks the cells of the central nervous system.

“Engineered probiotics could revolutionize the way we treat chronic diseases,” said Francisco Quintana, PhD, a lead author of the study and a professor of neurology at Brigham and Women’s Hospital, in a statement. “When a drug is taken, its concentration in the bloodstream peaks after the initial dose, but then its levels go down. However, if we can use living microbes to produce medicine from within the body, they can keep producing the active compound as needed, which is essential when we consider lifelong diseases that require constant treatment.”

What researchers learned in multiple sclerosis probiotic study

Quintana and colleagues reported in their study that probiotic bacteria engineered to produce lactate can activate a biochemical pathway used by dendritic cells — immune cells found in both the brain and the gastrointestinal tract — to stop other immune cells from attacking the body.

“The mechanism we found is like a brake for the immune system,” said Quintana. “In most of us, it’s activated, but in people with autoimmune diseases, there are problems with this brake system, which means the body has no way to protect itself from its own immune system.”

“By using synthetic biology to get probiotic bacteria to produce specific compounds relevant to diseases, we can take the benefits of probiotics and amp them up to the max,” he added.

Mice injected with the bioengineered bacteria experienced fewer symptoms of an MS-like disease, the researchers reported.

The potential for using gut bacteria to treat autoimmune conditions

Quintana also told Medical News Today that using gut bacteria to stop the immune system from attacking the body “stands by itself as a potential therapy” but also can be used in combination with other treatments for autoimmune diseases.

“This suppresses the autoimmune response that destroys myelin in the brain, but there are processes other than lymphocytes involved in diseases like MS that combination therapy can address,” he said. “Our therapy can at least slow down or reduces damage, while other therapies could regenerate” myelin, the protein sheath protecting nerve cells that is attacked by the immune system in MS patients, he said.

The link between the gut and the brain may not seem immediately obvious, but as Quintana explains, “The microbiome fine tunes our immune system, but in people with autoimmune diseases that system goes wrong. We know that the lymphocytes that cause damage in the brain are coming from the gut, so we stop them from going from the gut to the brain.”

The dendritic cells found in the gut and brain aren’t identical to each other, he adds, “but the mechanisms that control them seem to be shared.”

The health benefits from the gut microbiome

Researchers are increasingly looking at ways to manipulate the gut microbiome to provide therapy for diseases.

In a 2021 study, for example, Quintana and colleagues modified a strain of yeast found in the gut in order to treat symptoms of inflammatory bowel syndrome.

Dr. J. William Lindsey, the director of the Division of Multiple Sclerosis and Neuroimmunology at the University of Texas Health Science Center at Houston, told Medical News Today that the new study relates to research conducted in recent years showing that a high-fiber diet can increase lactate production and modulate the immune response.

“This is a more direct approach than what naturally occurs with certain diets,” he said.

To date, the U.S. Food and Drug Administration (FDA) has approved more than 20 drugs to treat MS, “all of which affect the immune system in some way,” said Lindsey.

While not specific to MS, the findings by the Brigham and Women’s researchers follow “a very interesting direction with lots of potential in terms of treatment that should have limited side effects,” he said.

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