In its vital function of providing the body with oxygen, the lung is connected to the outside environment by a large exchange surface. This boundary between lung tissue and outside air is inhabited by a specific microbial flora, the so-called lung microbiome. The exact function of this microbiome has been scarcely researched. A scientific team led by Profs. Alexander Flügel and Francesca Odoardi at the Institute for Neuroimmunology and Multiple Sclerosis Research, University Medical Center Göttingen, have shown a close relationship between the lung microbiome and the brain. The researchers found out that the lung microbiome regulates the activity of microglia, the “brain’s immune cells.” This newly ascertained lung-brain axis is significant for disease processes: the exact composition of the lung microbiome determines the susceptibility of developing an autoimmune inflammation in the brain such as occurs in multiple sclerosis. The experimental results of this work were published today, 23 February 2022, in the online edition of the journal Nature.