gut bacteria and ms

Gut bacteria may activate cells that trigger MS

Certain gut bacteria may activate pro-inflammatory immune cells in the intestine, which then make their way to the brain, a new mouse study has found.

T-cells are immune cells that are heavily involved in the immune response. Autoreactive T cells do exist in a health immune system and do not necessarily induce central nervous system (CNS) autoimmunity such as multiple sclerosis (MS).

When T-cells infiltrate the CNS, this has been shown to induce CNS inflammation, but the process that triggers them to do so has not been discovered.

Researchers in this study altered mouse T-cells to give them a receptor that binds to myelin oligodendrocyte glycoprotein (MOG), a part of myelin that T-cells often target in MS. Mice were then injected with these cells and scientists monitored their movement and activation.

They observed that these cells were activated in the ilea lamina propria (LP), which is a layer of connective tissue in the small intestine.

Next the scientists put the altered T-cells into mice who had been engineered to have no gut bacteria. The myelin-targeting T-cells did not activate in the ileal LP, which showed gut bacteria in this area of the intestine was needed for activation.

The researchers speculated that this activation in the gut might be due to certain gut bacteria having proteins shaped similar to myelin, which allowed the T-cell’s receptors to bind to it and cause inflammation – although more research is needed to both test the theory and identify which bacteria in particular may do this.

Next the scientists tracked the T-cells as they left the ileal LP and found that myelin-targeting cells activated in this portion of the gut could then migrate into the spinal cord and brain.

These cells began turning on genes characteristic of Th17 cells, a type of T-cell which is implicated in MS development.

The research team concluded that the findings provided a concept of how myelin-targeting T-cells could become activated and travel to the brain and cause inflammation which leads to the development of MS.