10/14/2026
Researchers have identified toxin-producing gut bacteria that may help trigger multiple sclerosis (MS) in genetically susceptible people. The findings suggest a possible environmental trigger, but do not prove that these bacteria cause MS in humans.
The 2023 study, published in the Journal of Clinical Investigation, involved researchers at Weill Cornell Medicine in New York, including Yinghua Ma, David Sannino and Timothy Vartanian. It examined epsilon toxin (ETX), produced by certain strains of Clostridium perfringens, a bacterium associated with the small intestine.
Using highly sensitive PCR methods to detect bacterial DNA, the team found that people with MS were more likely than healthy controls to carry ETX-producing strains. These strains were also more abundant in the MS group.
Among ETX-positive samples, type D strains were most common, while fewer type B strains were detected. Both types can produce ETX, so the finding concerns toxin-producing strains rather than one bacterial subtype alone.
The researchers also tested ETX in experimental autoimmune encephalomyelitis (EAE), an established animal model used to study MS. ETX replaced pertussis toxin, which is commonly used to help immune cells access the central nervous system in this model.
The animals developed inflammatory damage to myelin, the protective covering around nerve fibers, across several brain regions. This pattern resembled MS more closely than disease concentrated mainly in the spinal cord.
ETX targets blood vessels in the central nervous system and can disrupt the blood-brain barrier, allowing greater immune-cell entry. Separate experimental research supports pathways through which ETX increases this barrier's permeability.
Together, these findings strengthen the idea that a bacterial product from the gut could help initiate or worsen brain inflammation in susceptible individuals. MS organizations have highlighted the research as a meaningful step toward understanding potential disease triggers.