Studies using gut bacteria to induce MS-like symptoms in mice have supported the concept that some bacteria and viruses can impact MS.
The study was conducted at California Institute of Technology (Caltech) and led by researchers Sarkis K. Mazmanian, an assistant professor of biology at Caltech, and postdoctoral scholar Yun Kyung Lee.
Mazmanian and his colleagues tried to induce MS in animals that were completely devoid of the microbes that normally inhabit the digestive system, but the sterile animals did not get sick. They then inoculated mice with bacteria that had been shown to lead to intestinal inflammation. The bacteria was also known to induce the appearance of a particular immune-system cell that causes an inflammatory cascade that leads to the animal model of MS, known as EAE.
Giving the formerly germ-free mice a dose of one species of segmented filamentous bacteria induced this cell not only in the gut but also in the central nervous system and brain-and caused the formerly healthy mice to become ill with MS-like symptoms.
"It definitely shows that gut microbes have a strong role in MS, because the genetics of the animals were the same," Mazmanian said. The biologists note, however, that the microbes aren't a direct cause of MS, but encourage conditions that could allow the disease to develop.
"We would like to suggest that gut bacteria may be the missing environmental component," he said. "Perhaps treatments for diseases such as multiple sclerosis may someday include probiotic bacteria that can restore normal immune function in the gut... and the brain," Mazmanian added.
The study appears online in the Proceedings of the National Academy of Sciences (ANI.)
Ben Thrower, M.D., the MSF’s senior medical advisor called the report “very interesting,” noting that it is important to understand that the research does not indicate that an active infection with gut bacteria causes MS.
“Other caveats would be that this is an animal EAE model, not human MS,” he says. “Otherwise, it does fit with our concept that some bacteria andviruses can impact MS by fooling the immune system through molecular mimicry. This leads the immune system to attack myelin as if it were a bacteria or virus. Another impact may be that this bacteria stimulates the immune system in people with MS leading, to an increase in symptoms (a pseudo-relapse.)”