Researchers in Germany say they have found evidence that MS is triggered by natural intestinal flora, the so-called friendly bacteria that reside in the gut. Their study involved genetically engineered mice with normal gut bacteria that developed brain inflammation similar to MS in humans. Researchers at the Max Planck Institute of Neurobiology in Martinsried in Munich, Germanypublished the results of their study in the journal Nature.
The human gut is home to some 100 billion bacteria from 2,000 different species, comprising 10 to 100 times more genes than in our entire genome. These microorganisms not only help us digest food, they are also essential for gut development. And they also play a role in promoting autoimmune disease, say the Max Planck researchers.
In the study, the genetically modified mice were allowed to continue with their normal gut bacteria intact. The intestinal flora were removed in the other mice and they were kept under sterile conditions. The mice that kept their gut bacteria developed MS-like symptoms.
According to the researchers, the bacteria first activated the immune T-cells, then the B-cells, which resulted in an attack on the myelin layer in the brain. The same could happen in humans with a corresponding genetic predisposition, they say.
In their background information, the Max Planck researchers refer to previous research that shows active MS lesions have "inflammatory changes suggestive of a combined attack by autoreactive T and B lymphocytes against brain white matter." (Lymphocytes are the white blood cells of the immune system).
They explain that T and B cells are normally innocuous members of a healthy immune system, but it appears something triggers them to become "autoaggressive", and the cause is commonly assumed to be environmental, with infection being the most common reason given.
One implication of this study is that nutrition may play a key role in the development of MS, since diet largely determines the types of bacteria that colonize the gut. The team now wants to investigate the complete microbial genomes of people with MS and compare them to people without MS.