"Cell" How do gut bacteria shape the "circadian rhythm" even in a dark environment

According to a study published yesterday (July 28, local time) in the journal Cell, the microbes in the mouse gut synchronize the animal’s immune response with its daily activity patterns

Christoph Thaiss, a microbiologist at the University of Pennsylvania, said these findings confirm that the microbiota is an important link between the animal’s biological clock and the immune system

"In a way, this is a long-awaited discovery," he said

See " Microbes shape the circadian rhythm of the mouse intestine "

In order to establish a link between circadian rhythm, microbiota, and host immunity, John Brooks, co-author of the study and a postdoctoral fellow in Lora Hooper's laboratory at the University of Texas Southwestern Medical Center in Dallas, said, start by looking for any antibacterial protein-as an innate Peptides secreted as part of the immune response-their production in the intestines of mice shows rhythmicity

He found that at the beginning of the night, when the mice became active and began to eat, the levels of multiple proteins were higher than the levels when they began to rest during the day

Brooks, Hooper, and his colleagues screened images of mouse intestines to find clues that might drive the REG3G cycle and found segmented filamentous bacteria (SFB) that adhere to the intestinal wall

Brooks said these antibacterial proteins are expensive to produce, so you should produce them when you absolutely need them

They found that inoculation of SFB to germ-free mice caused REG3G to start circulating, while in mice lacking REG3G, SFB still showed a rhythmic pattern attached to the intestinal wall, indicating that it was indeed bacteria driving the REG3G cycle, not The REG3G cycle drives bacteria

Based on previous research by Thaiss and others, Brooks said that he suspects that the SFB in the intestine of mice gets its own rhythm from the animal’s eating pattern, which is regulated by the mammal’s biological clock

In general, Brooks said, these results indicate that the evolution of the mouse intestine is to predict the most dangerous time of day and prepare for immune defense accordingly

The research team is interested in whether these immune cycles may actually affect the health of the mice.

Brooks pointed out that Typhimurium is not a typical bacterium because it is more likely to infect mice when the intestinal tract becomes inflamed

Brooks explained that the research team used Salmonella in this experiment because it is one of the few pathogens that can easily infect mice even if they are not pretreated with antibiotics.

And Listeria may show the opposite pattern to Salmonella, Hooper said

Thaiss said that he was particularly pleased to see the Salmonella experiment included

Julie Gibbs, a temporal biologist at the University of Manchester in the UK (who did not participate in the study), said that it is not yet clear how this microbial-driven immune cycle works in humans; SFB exists in the human body.
However, it is unclear whether they adhere to the intestinal wall rhythmically
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Nonetheless, she said, the research team’s findings suggest a possible explanation for a well-known link in human health: the link between sleep disruption and disease risk
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Gibbs said: “We know that shift work is usually harmful to our health, has a negative impact on the immune system, and has the risk of inflammatory diseases
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In addition, we know that shift work is related to eating disorders
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So I think if this disorder Our diet may affect the rhythmic microbiota, which may have a knock-on effect on our immune system and immunity, and research on shift workers may yield some new discoveries
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The microbiota coordinates diurnal rhythms in innate immunity with the circadian clock