Photo worth seeing: Through the lung barrier

The bacterium Pseudomonas aeruginosa (yellow-green) breaks through the protective barrier and penetrates the lungs. © Benoit Laventie, Biozentrum, University of Basel

Pseudomonas aeruginosa is a rod-shaped bacterium that occurs in moist environments such as surface water, sinks or toilets. It is a pathogen that can cause wound and urinary tract infections, blood poisoning and life-threatening pneumonia. The World Health Organization (WHO) considers Pseudomonas aeruginosa to be one of the most dangerous bacterial pathogens that are resistant to several antibiotics. This makes the bacterium particularly life-threatening for people with weakened immune systems. In patients who are on artificial respiration, the mortality rate after infection is up to 50 percent.

Because of this threat, a research team led by Urs Jenal from the Biozentrum of the University of Basel investigated how the pathogen can penetrate the lungs. To do this, the team cultivated lung microtissue in the laboratory, which they used to mimic the infection process. Pathogens should normally be prevented from penetrating by the thin layer of mucus on the surface of the lung tissue. However, the Pseudomonas bacteria can overcome this protective barrier and infect the lung tissue.

To do this, the pathogens use the so-called goblet cells, which produce the mucus for the surface. The Pseudomonas bacteria penetrate these cells and multiply there. They then kill the mucus cells and cause them to burst. This creates cracks in the tissue layer through which the pathogens can overcome the protective barrier. One such break can be seen in the photo. The Pseudomonas bacteria (yellow-green) have settled in the broken areas and can now penetrate deeper into the lungs.

The results provide Jenal and his colleagues with insight into how the Pseudomonas bacterium behaves during the infection process, which could help develop effective methods to combat pathogens in the future.

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