Multiple sclerosis is caused by a combination of genetic and environmental factors. For a long time, pathogens were believed to be such external influences. According to scientists from the Max Planck Institute of Neurobiology in Martinsried, however, it is apparently not harmful bacteria that trigger multiple sclerosis, but beneficial ones specifically, the natural intestinal flora, which every human being needs for digestion. The researchers discovered that genetically modified mice develop an inflammation in the brain similar to the human disease if they have normal bacterial intestinal flora. The microorganisms begin by activating the immune system's T cells and, in a further step, the B immune cells. The findings suggest that in humans with the corresponding genetic predisposition, the essentially beneficial intestinal flora could act as a trigger for the development of multiple sclerosis.
The human intestine is a paradise for microorganisms: it is home to roughly 100 billion bacteria made up from 2,000 different bacterial species. The microorganisms of the intestine are not only indispensable for digestion, but also for the intestine's development. Altogether, this diverse community comprises between ten and one hundred times more genes than the entire human genome. Scientists therefore frequently refer to it as the "extended self". However, the intestinal bacteria can also play a role in diseases in which the immune system attacks the body itself. Intestinal bacteria can thus promote autoimmune disorders such as Crohn's disease and rheumatoid arthritis.
On the one hand, the likelihood of developing multiple sclerosis, a disease in which proteins on the surface of the myelin layer in the brain activate the immune system, is influenced by genes. On the other, however, environmental factors have an even greater impact on the disease's development. Scientists have long suspected that it is caused by infectious agents. The Max P
|Contact: Dr Gurumoorthy Krishnamoorthy |