Researchers discovered that a compromised immune system changes gut bacteria.

thA new study, published by the Instituto Gulbenkian de Ciencia, in the journal of Nature Communications, has revealed that the immune system controls the composition of gut bacteria. If the immune system is compromised the process of adaption of gut bacteria is affected.

Gut bacteria adapt and evolve to efficiently cope with different stimuli including the diversified diet that is ingested on a daily basis. The diversity pf bacteria increases which needs to be checked by the immune system in order to prevent chronic diseases such as inflammatory bowel disease.

Chronic health conditions arise when there is a disruption in the community of gut bacteria and other studies have shown a link between chronic health conditions and a specific type of bacteria, for example type 1 and type 2 diabetes.

The study investigated how Escherichia coli (E. coli), one of the first bacteria to colonize the intestine at birth, evolved in healthy mice. The scientists used a mouse model that did not have lymphocytes, (cells of the immune system).

In healthy animals rapid metabolic adaptations to diet was observed, in immune compromised mice the changes were slower. Individual variations of gut bacteria were detected in animals that lack lymphocytes.

“We observed that this feature is due to changes in the composition of the community of bacteria in the intestine, which is more similar across individuals with a healthy immune system, and is quite diverse in animals with an immune compromised system,” said Joao Batista, first author of this study.

“Our work shows that it is possible to predict the evolution of commensal bacteria in healthy organisms, but the same is not true in organisms with problems in their immune system, said Isabel Gordo. “Therefore, the use of generalist therapies to treat people suffering from intestine pathologies that result from an impaired immune system, such as inflammatory bowel disease, may not be the best approach. Instead, therapies based on personalized medicine should be considered, accordingly to the composition of gut bacteria of each person.”


Adaptive immunity increases the pace and predictability of evolutionary change in commensal gut bacteria, João Barroso-Batista et al., Nature Communications, doi:10.1038/ncomms9945, published online 30 November 2015.

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