As we announced earlier, we will present the award-winning contributions of the young female scientists here on our Homepage. We will start with the project of Charline Sommer, who is working at the Fraunhofer Institute of Toxicology and Experimental Medicine (ITEM). Her work focussed on the various age-related immune reactions on the Pseudomonas aeruginosa bacteria.
With increasing age, the risk of contracting serious infections also increases. This also particularly concerns pathogens which only seldomly cause infection in healthy adults, such as Pseudomonas aeruginosa, for example. As a typical water bacteria, it occurs practically everywhere that is damp – in damp soil and water, in washbasins and sometimes also in drinking water. If a person’s immune system is affected, as it is for example with seniors over 65 years, the bacteria can settle in the lung and thus lead to pneumonia, which may also be fatal.
Certain immune cells, neutrophils, play a significant role in combatting bacteria. These cells can ingest germs (also called phagocytosis) or release substances which kill the bacteria directly or indirectly. Furthermore, neutrophils are also able to release their genetic material, their DNA. The resulting net-shaped neutrophil extracellular traps (NETs) can capture pathogens like bacteria or also viruses and thus contribute to the containment of the infection. In excessive amounts, however, these structures can also damage tissue and thus worsen the course of the disease.
To examine the influence of the aging immune system on P. aeruginosa pneumonias, we have populated vital lung slices from young adult and older mice with the bacteria. In response to the infection, the tissue from old animals produced more inflammation markers and messengers than the lung slices from young animals. Transferring this to humans, colonization could thus lead to an enormous inflammatory reaction, to which the body is no longer able to react. Through the messengers, the immune system is alerted and immune cells, like the neutrophils, are recruited to infect it. For this reason, in a second series of experiments, we have cultivated neutrophils and P. aeruginosa bacteria together. We were thus able to show that more NETs are formed when neutrophils from old mice are used compared to those from young mice. In older humans, this could lead to increased damage of the lung tissue and also strengthen the severity of the disease progression. These findings could be useful for future therapies of P. aeruginosa pneumonias in the elderly. By restoring the balance of the immune system, the infection could be moderated and the prognosis for the patients generally improved.
Photo: Mike Auerbach
Prof. Dr. Werner Seeger (chairman of the DZL board) awarding Charline Sommer