Rapid genetic switches

The human gut is constantly influenced by changes in the environment. To keep up, gut bacteria must adapt quickly. They do this through a process called functional plasticity, which allows them to change their behavior and functions in response to factors like nearby microbes, health status and what individuals eat.

A previous study by the Geva-Zatorsky lab discovered that one way gut bacteria adapt to environmental changes is through DNA inversions—rapid genetic switches that help them respond and defend themselves.

In their current study, published on May 28, the researchers investigated how these DNA inversions occur in response to dietary factors. They found that consuming soft drinks, which contain white sugar, can alter the DNA of gut bacteria and, in turn, impact the host’s immune system.

The study focused on Bacteroides thetaiotaomicron—a prominent gut member that takes part in preventing gut inflammation, preserving the gut mucus layer and protecting the host from pathogen invasion.

The team members examined the effects of consuming different dietary components on the DNA inversion profile of these bacteria—in vitro, in mice and in humans. They discovered that white sugar consumption causes DNA inversions in these bacteria, which led to changes in inflammatory markers of the immune system, including ones in T-cell populations, cytokine secretion and gut permeability.

Effects are reversible

The good news is that these effects are reversible; once mice stopped consuming white sugar, the bacterial DNA inversion state reverted, and the immune system’s state returned to normal.

The study stresses the importance of studying complex effects of nutrition on the microbiome, assessing that it will allow tailored dietary recommendations for humans to improve their immune system’s state and health in general.

The research was supported by the Technion President’s Fund; RTICC–The Rappaport Technion Integrated Cancer Research Center; the Alon Fellowship for Outstanding New Faculty; the Seerave Foundation; CIFAR (Canadian Institute for Advanced Research); and the European Research Council.