WASHINGTON, Oct. 4 (Xinhua) -- Scientists at Washington University School of Medicine in St. Louis identified a type of immune cell that sets the clock for the gut, which may explain why disruptions to circadian rhythms are linked to gastrointestinal problems.
The study published on Friday in the journal Science Immunology showed that cells known as type 3 innate lymphoid cells (ILC3) are responsible for keeping the intestine operating in a normal, healthy manner.
Shift work and jet lag tend to disrupt sleep schedules and digestive rhythms, increasing risks of intestinal infections, obesity, inflammatory bowel disease and colorectal cancer, according to the researchers.
They found that clock genes are highly active in ILC3 cells, and when they eliminated a key clock gene from mice, the animals failed to produce a subset of ILC3 cells, thus struggling to control a bacterial infection in the gut.
The findings suggested that targeting clock genes could affect immune cells and help counter the negative effects of erratic sleep schedules linked with intestinal illnesses.
"What we've found here is that circadian rhythms directly affect the function of immune cells in the gut, which could help explain some of the health issues we see, such as inflammatory bowel disease and metabolic syndrome," said the paper's senior author Marco Colonna, professor of Pathology at Washington University.
ILC3 cells maintain a balance in the gut by strengthening the barrier between the trillions of bacteria that normally live inside the gut and the cells that make up the intestine itself.
Those cells also produce immune molecules that help the gut's immune system avoid overreacting to harmless microbes and food particles, while preserving its ability to combat disease-causing bacteria, according to the study.
The researchers found that activity of clock genes in ILC3 cells taken from mouse intestines varied in a predictable pattern over the course of a day. When they put some mice on a schedule similar to one experienced by a shift worker, those cells functioned abnormally.
The researchers said that lacking of ILC3 cells or a change in ILC3 behavior could affect the body's ability to fight intestinal infections.
"The emerging relevance of the circadian regulation in gut health is likely to impact medical and hospital practice," Colonna said.