Newswise — New research published in Science reveals that immune systems develop specific genes tailored to combat common bacteria, including those commonly found in food. Contrary to previous theories suggesting a general role of antimicrobial peptides in killing various bacteria, the study focused on how the immune systems of fruit flies are influenced by the bacteria present in their food and environment.
Researchers from the Swiss Federal Institute of Technology and the University of Exeter conducted the study and identified two peptides. Each of these peptides is responsible for controlling a particular bacterial species that is frequently encountered by the fruit flies.
Dr. Mark Hanson, from the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall, explained that the type of bacteria an animal encounters is shaped by its food and environment. The findings shed new light on the mechanisms underlying the immune response to specific bacteria, providing valuable insights into the interaction between immune systems and common microbial threats.
As a result, this process significantly influences their "microbiome," which refers to the collection of microbes residing in and on their bodies. The study demonstrates how immune systems adapt in response to this microbial community to effectively control common bacteria that could otherwise pose a threat.
In immune terms, the study validates the adage "you are what you eat," as the flies' immune systems contain peptides with highly specialized functions tailored to regulate common bacteria.
One such bacterium, Acetobacter, commonly found in the fruits consumed by flies (and humans), can be harmful if it escapes the gut and enters the bloodstream. However, the research reveals that various fly species possess a specific peptide called Diptericin B, specifically designed to control Acetobacter.
According to Dr. Hanson, this peptide acts as a "silver bullet" capable of targeting and eliminating this specific bacterium. Without it, flies become exceptionally vulnerable because Acetobacter is prevalent in decaying fruit. The study underscores the critical role of these specific peptides in safeguarding flies from potential harm caused by common bacteria in their environment.
The study further reveals compelling evidence of "convergent evolution," wherein distinct species develop similar responses to environmental challenges. In this particular case, the fly species examined in the study diverged from a shared ancestor approximately 100 million years ago, yet both of them independently evolved a Diptericin B peptide to regulate Acetobacter.
Interestingly, closely related fly species that do not primarily feed on fruit have gradually lost their Diptericin B peptides over time. This loss can be attributed to the decreasing prevalence of Acetobacter in their environment, as it is no longer a common threat to them.
Dr. Hanson suggests that this intriguing evolutionary process may offer insights into the susceptibility of humans to specific infections. By studying how various organisms adapt their immune responses to combat common threats, researchers can gain valuable knowledge that might shed light on why certain infections affect humans differently.
According to Dr. Hanson, the complexity of how our bodies combat infections becomes clearer through research like this. It offers a fresh perspective on our immune system, prompting us to question the reasons behind its design. Understanding these mechanisms can lead to more effective strategies for fighting infections, even those that have developed resistance to antibiotics.
These studies provide profound insights into life's fundamental workings, with potential applications that are crucial in our world. The research was made possible through funding from the Swiss National Science Foundation and the Novartis Foundation.
The paper's title is "Ecology-relevant bacteria drive the evolution of host antimicrobial peptides in Drosophila."
The research was funded by the Swiss National Science Foundation and Novartis Foundation.
The paper is entitled: “Ecology-relevant bacteria drive the evolution of host antimicrobial peptides in Drosophila.”
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