Credit: Diego Galagovsky - Hanson et al.
Researchers at Ecole Polytechnique Fédérale de Lausanne have published research shedding new light on how selective pressures drive the evolution of antimicrobial peptides (AMPs). By studying fruit fly Diptericin (Dpt) evolution the researchers were able to establish a pattern of evolution based on environmental and dietary factors.
Previous research into AMPs has shown that they evolve rapidly, however, little was known about what drove this rapid evolution. By studying the fruit fly Drosophila the team of researchers was able to better understand the selective pressures that drive the rapid evolution of AMPs in response to their microbial environment.
The research, published in Science, discovered that DptA and DptB, different types of Diptericins, serve a specific function in the fruit fly's defense against various bacteria. The findings showed that DptA protects against Providencia rettgeri while DptB protects against Acetobacter, however, these Diptericins had no overlap in protections with each other. By analyzing the evolutionary history of these two genes, scientists were able to uncover that they evolved differently based on the fruit flies environment and what they fed on.
Further research into various ecological niches such as mushroom-feeding or being plant-parasites showed that the fruit flies lost one or both of the Diptericin genes due to a lack of Providencia rettgeri and Acetobacter, proving the theory that the fly’s immune system evolves as a result of its environment. These findings could present a new model of AMP-microbiome evolution, one that represents numerous changes to the genes based on the host's ecology and various other environmental factors.
“The way our bodies fight infections is very complex,” says Mark Hanson - lead author of the paper. “But this sort of research helps us to view our immune system in a new light. It helps us ask: ‘why is our immune system made the way it is?’ That can help us learn how to fight infections, including ones that resist antibiotics.”
The research highlights the evolutionary forces that mold a host's immune system and how it adapts to fight against specific pathogens within its environment.