Everyone knows what the brain is, but not everyone knows what the microbiome is. It is the complex of viruses, bacteria and fungi that play a crucial role in our health and cognitive functions. A whole population of collaborators living in our bodies, to put it briefly.
Also known as a microbiota, this 'army' has been based in the gastrointestinal tract for a long time, according to science. We have recently known that it is also found in the skin. According to science, for a long time it was believed that different areas of the body were devoid of it: for example the eye and the womb. Recent diagnostic advances have recently made it possible to identify a microbiome of the placenta and one of the eye, both of which are present in healthy people. At this point it is reasonable to expect other discoveries shortly.
Are we sure, for example, that the brain is a sterile, bacteria-free area, or does it have a microbiome? This is the object of the incredible intervention at the conference of the US Society of Neuroscience last November 2018. A research team from the University of Alabama – Birmingham (UAB), led by Dr. Rosalinda Roberts, showed high resolution microscopic images of the brain of mice and humans. These images clearly show bacteria inside astrocytes, the cells that interact with neurons in the brain.
Like so many groups making astounding discoveries, this one was not looking for bacteria in the brain at all. The fact that the brain is a sterile area was well established throughout the scientific world.
Researcher Courtney Walker was microscopically comparing images of the brains of healthy people with those of people with schizophrenia to assess any structural differences when she came across the discovery. After the first surprise, the analysis was extended to all the human brains that the laboratory had in analysis. All 34 had bacteria.
The first investigations
To determine whether their presence was the result of contamination after death, Dr. Roberts and her team studied the brains of mice in life and immediately after death. Surprisingly, bacteria were found there too.
Perhaps the contamination occurred in the preparation of the brain samples to be analyzed? Even analyzes in sterile environments have provided clues in one direction.
The in-depth analysis
At this point the team used RNA sequencing to identify what type of bacteria were in the brains of mice and humans. Everyone is Firmicuti, proteobacteria e bacteroides commonly found in the intestine. How did they end up in the brain?
These first, astonishing observations left many questions open: Are these bacteria of the "cooperative" or pathological type? Does the amount and composition of the brain microbiome change over time? Where did these bacteria come from? Questions that will perhaps be answered in connection with the recent discovery of an immune system in the brain. All these changes will lead to the explosion of what is now a still emerging scientific field: psychoneuroimmunology.
It has become as archaic as the 1300s beliefs believe that bacteria are just an enemy to fight. For some time we have known that we host entire cities, nations, planets in our bodies: endless populations of organisms that live with us, “work” with us and help us in many cases.