“If an animal, for example an insect, is attacked by bacteria, it always responds with a cocktail of antimicrobial peptides,” explains Jens Rolff. This contrasts with the use in medicine, in which often only one antibiotic is used. “We asked ourselves why nature always came up with this other solution,” says biologist Jens Rolff. One explanation is that these cocktails of antimicrobial peptides are often synergistic, which means that the individual substances complement each other to enhance the effect. Smallest changes in the sequences of individual antimicrobial peptides can have a great effect. “These differences probably occur because different animal or plant species are adapted to specific combinations of microorganisms in their environment,” explains Professor Rolff.

If scientists succeed in translating knowledge about the evolution of antimicrobial peptides and their diversity to applications in synergistic cocktails, there is a chance that in the long term, antimicrobial peptides could be used against infections

“The combination of evolutionary insight and combination therapies could help to slow down resistance evolution significantly,” explains Jens Rolff. Another promising perspective is to combine antimicrobial peptides with antibiotics. This could even make it possible for antibiotics that are spent due to widespread resistance, to be used again in combination with antimicrobial peptides, thereby expanding the arsenal to combat resistant germs.

One problem is that antimicrobial peptides are often very similar in their mechanisms of action and therefore the risk of resistance to the body's own antimicrobial peptides in humans needs to be investigated very carefully. “Many antimicrobial peptides that are currently being clinically tested are derived from human antimicrobial peptides,” explains biologist Rolff. He says that it is not an unsolvable problem, but one that has not been addressed so far.

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