Multiple sclerosis and microbiome

Previous work has shown that mice engineered to develop experimental autoimmune encephalitis (EAE), a model for multiple sclerosis (MS), remain disease free when raised in a germ-free environment, suggesting that commensal microbiota mediate brain autoimmunity.

To understand the role of human gut microbiota in MS, researchers analyzed the microbiomes of 71 MS patients and 71 healthy controls, ages 19–71, and found significant differences in the relative abundances of certain bacterial genera. Acinetobacter and Akkermansia were significantly more abundant in MS patients than in controls, whereas Parabacteroides was less abundant in patients than in controls.

Exposing human peripheral blood mononuclear cells to extracts from Acinetobacter and Akkermansia bacteria increased differentiation of proinflammatory T helper cells. Acinetobacter extracts also inhibited regulatory T cell (Treg) differentiation, whereas Parabacteroides extracts promoted Treg differentiation. Similar differences in T cell differentiation were observed in germ-free mice colonized with individual bacterial genera.

 According to the authors, the results could pave the way for microbiome-based therapies for autoimmune diseases.

In a related article, another group of researchers. examined 34 human identical twin pairs, ages 21–63, in which only one twin had MS. When microbiota derived from the twins were transplanted into EAE-susceptible mice, the mice receiving transplants from MS patients had a greater incidence of EAE than those receiving transplants from healthy donors.

The results suggest that components of the human microbiome can contribute to MS, according to the authors.

http://www.pnas.org/content/early/2017/09/05/1711235114

http://www.pnas.org/content/early/2017/09/05/1711233114