The discovery of the lung-brain axis


Smoking damages the lungs. But cigarettes have numerous other health effects, including an increased risk of multiple sclerosis (MS). In the case of the autoimmune disease, the body’s own defenses turn against itself, which, among other things, causes the insulating covering of myelin to detach from the neurons. But why does a load on the lungs affect cells in the brain?

Researchers at the University of Göttingen have now found evidence of a lung-brain axis that explains such connections. The composition of the lung microbiome determines the susceptibility to developing autoimmune inflammation of the brain.

Lung as an early warning system for sensitive brain tissue

The neuroimmunologists led by Francesca Odoardi administered a local antibiotic to the airways of the rats. As a result, certain bacteria whose cell walls contain so-called lipopolysaccharides accumulated in the lung tissue. These molecules are known to be able to cross the blood-brain barrier and alter microglia, the brain’s immune cells. In fact, the now increased amount of lipopolysaccharides blocked the microglia of these rodents. As a result, it was no longer possible for them to trigger MS by administering certain substances: the immune cells were unable to attack the body’s own tissue.

On the other hand, MS symptoms could easily be induced in animals that had not received any antibiotics in the lungs. If the scientists then administered only lipopolysaccharides, myelin degradation stopped. However, when they blocked the substance in the rats, the symptoms worsened. Compared to the well-known intestinal flora, the lungs are far less densely populated with bacteria, but that doesn’t make them any less important. According to Odoardi, it serves as an “early warning system for sensitive brain tissue”.



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