Anti-inflammatory gut bacteria type seen to reduce MS severity in mice

A specific type of gut bacteria known as Veillonella ratti — a bacterium shown to exert anti-inflammatory effects — reduced the severity of multiple sclerosis (MS) in a mouse model of the disease, according to a new study.

The research suggests that V. ratti changes the activity of other gut bacteria, ultimately increasing levels of an anti-inflammatory signaling molecule in the brain that dampens the activity of disease-driving immune cells.

“Our findings reveal a novel mechanism in which gut microorganism-derived metabolites [small molecules involved in metabolism] … suppress [brain and spinal cord] inflammation and suggest the potential of microbiome-based strategies for treating MS,” the researchers wrote.

The study, “Gut microbiome modulation by Veillonella ratti induces resistance to EAE pathogenesis via microbe-derived metabolites,” was published in the journal Experimental and Molecular Medicine.

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July 7, 2026 News by Margarida Maia, PhD

Study offers new clues to how gut bacteria may influence MS risk

The gut microbiome refers to the billions of bacteria and other organisms that live in the human digestive tract. A growing body of evidence has suggested that the gut microbiome can communicate with the immune system and influence immune responses throughout the body.

In line with that, the gut microbiome is often dysregulated in MS, with elevated levels of inflammatory species seen in the gut. This has led some researchers to wonder whether changing this microbiome’s composition could help treat the disease.

Testing the effects of a type of gut bacteria known as V. ratti

V. ratti is a bacterial species found in the digestive systems of mammals. Earlier studies have also shown that MS patients tend to have lower than normal levels of V. ratti in their gut microbiome.

To better understand its potential role in MS, a team led by scientists in South Korea tested the effects of adding V. ratti to the gut microbiome of mice with experimental autoimmune encephalomyelitis (EAE) — a lab-induced inflammatory disease that’s commonly used to model MS. In their experiments, the mice received daily oral V. ratti supplements starting one week before EAE was induced.

“In this study, we aimed to elucidate how human-derived V. ratti … modulates neuroinflammation and disease severity in EAE,” the team wrote, noting that this type of bacteria “may contribute to immune regulation and is a potential candidate for microbiome-based interventions in immune-mediated diseases such as MS.”

The results showed that mice treated with V. ratti had significantly less severe disease and showed less myelin damage. Myelin is a fatty substance that protects and insulates nerve fibers and is mistakenly damaged by misguided immune system attacks in people with MS.

[V. ratti] may contribute to immune regulation and is a potential candidate for microbiome-based interventions in … diseases such as MS.

The scientists also found that adding V. ratti to the gut changed which bacterial species were able to thrive in the gut microbiome. In particular, V. ratti reduced the abundance of bacteria that break down a signaling molecule called dioleoyl phosphatidylethanolamine (DOPE).

With fewer bacteria breaking down DOPE in the gut, more of this signaling molecule remained available to travel to other parts of the body, including the brain and spinal cord. Once there, the molecule reduced the inflammatory activity of immune cells that drive damage in EAE, the data showed.

The researchers also found that treating mice directly with purified DOPE led to reductions in disease severity similar to those seen with V. ratti supplementation. That result suggests that the molecule is a key mediator of V. ratti‘s protective effects.

“The therapeutic effects of V. ratti … in an EAE model are potentially mediated through the targeted suppression of [disease-driving inflammatory immune cells]. These effects are potentially driven by accumulation of the gut microbiome-derived metabolite DOPE,” the researchers wrote, noting that DOPE has “structural specificity [that] dictates its unique immunoregulatory functions.”

“Our findings provide novel insights into gut–[brain] communication and support the development of microbiome-based therapeutic strategies for MS,” the researchers wrote.

The researchers stressed that these results come from experiments in an animal model, so additional studies will be needed to see if similar approaches might benefit people with MS.