A study in mice showed that removing gram-negative bacteria in the gut decreased the number of brain lesions in mice that were genetically susceptible to them. These type of bacteria release endotoxin (also called LPS) and this stimulates a very strong immune response leading to uncontrolled inflammation. When mice were injected with LPS alone this caused an increase in the brain lesions.
This is further evidence that gut bacteria can affect brain integrity through inflammatory-mediated processes. The lead researchers in this study plan on looking at the gut microbiome in patients that are susceptible to these kinds of strokes and seizures.