Protection of the brain by the microbiome

Viral infections can cause brain-related issues, as is known from diseases such as the mad cow disease, the Zika virus and the West-Nile virus. A currently ongoing field of research is investigating the role of micro-organisms in the occurrence of other brain-related diseases such as Parkinson’s and Alzheimer’s. The downside of viral infections in the brain, is that brain tissue is not repaired by the human body, as normal bodily tissue would be, after damage. As such, this may cause permanent brain damage, and a proper therapy for blocking such viral infections is needed. The microbiome has been attributed a role in the development of the immune system, by means of the “priming” of immune cells to the surface receptors of micro-organisms. This process results in the body being able to discern between pathogens and “normal” residents of the gut.

As the brain also has an immune response by the microglial cells, researchers in Utah tried to determine the role of the microbiome in viral infections in the brain. The found that bacteria-deficient mice, had a compromised immune system, and were consequently less able to ward of an induced hepatitis infection. Indeed, this decline in immune response was a consequence of the lack of maturation of the immune system of these mice, due to the absence of a microbiome-immune interaction in the early development of these mice. In short, these mice had a lower concentration of the main immune cell, the T-cell. Finally, the microbiome-immune deficient mice indeed showed a higher degree of damage in the brain after the induced hepatitis infection.