Circadian Rhythm Boosts Body’s Ability to Fight Intestinal Bacterial INfection

Circadian rhythms can boost the body's ability to fight against intestinal bacterial infections, according to a new finding by researchers at UC Irvine.

The circadian rhythm is a 24-hour cycle in the bodily processes of living beings, including animals, plants, cynobacteria and fungi. The rhythms are generated endogenously and can be moderated by external cues such as sunlight and temperature, and adapt to them accordingly. The disruption of the circadian rhythm greatly influences people's health.

The study, which appears in Proceedings of the National Academy of Sciences, suggests that targeted treatments may be effective for pathogens such as salmonella, which brings about a strong immune system response governed by the circadian genes. This also provides an explanation as to why a disruption in the day-night pattern that is experienced by night shift workers increases their susceptibility to infectious diseases.

The study was led by one of the leading researchers on circadian rhythm genetics, Paolo Sassone Corsi from UC Irvine, in collaboration with Marina Bellet from University of Perugia, Italy.

"Although many immune responses are known to follow daily oscillations, the role of the circadian clock in the immune response to acute infections has not been understood," said Sassone-Corsi in a press statement. "What we're learning is that the intrinsic power of the body clock can help fight infections."

The study report suggests that nearly 15 percent of the human genes are governed by the day and night pattern of the circadian rhythm, including those genes that react to intestinal infections.

For the current study, a test was conducted on mice that were infected with salmonella. During the test, researchers noticed that the circadian-controlled genes direct the immune response to attack pathogens, leading to day-night differences in infection potential and in the ability of the immune system to deal with pathogens.

The circadian rhythms in mice are opposite to that of humans, as they are nocturnal. Certain differences exist in the immune system of mice and humans, but these tests offer hints on how circadian-controlled intestinal genes control the everyday changes in the effectiveness of the immune system of humans.

"This gives us the ability to target treatments that supplement the power of the body clock to boost immune response," Sassone-Corsi concluded.