Daijiworld Media Network – New Delhi
New Delhi, Jul 4: Psychological stress can alter the gut microbiome and accelerate ageing-related changes in blood-forming stem cells, potentially increasing the risk of conditions such as heart disease and diabetes, according to a new study conducted in mice.
The findings, published in the journal Cell Stem Cell, suggest that chronic psychological stress affects the body's hematopoietic stem cells in the bone marrow by disrupting the balance of gut bacteria.
Researchers from Sun Yat-sen University in Guangzhou, China, found that stress-responsive regions of the brain regulate the intestinal microbiota, which in turn influences the function of blood-forming stem cells.
"Our research shows how stress-responsive brain regions regulate the balance of the intestinal microbiota, which ultimately affects the function of hematopoietic stem cells," senior author Meng Zhao said.
Previous studies have shown that chronic stress can affect immune function and the production of immune cells in the bone marrow through inflammatory pathways and stress hormones associated with the body's "fight-or-flight" response. However, the mechanism by which stress signals travel from the brain to the bone marrow had remained unclear.
To investigate this, researchers studied four different mouse models exposed to chronic psychological stress, examining interactions between the brain, intestine and bone marrow.
The study found that chronic stress reduced activity in two key brain regions — the medial prefrontal cortex, which processes emotional and cognitive information, and the periaqueductal gray, which plays an important role in pain regulation.
Reduced activity in these brain regions triggered several physiological changes, including the loss of hematopoietic stem cells and reduced production of lymphocytes, a type of white blood cell essential for immune defence.
Researchers also observed significant changes in the gut microbiome. Stressed mice showed a decline in Lactobacillus reuteri, a beneficial bacterium that helps maintain a healthy intestinal environment, along with reduced levels of spermidine, a naturally occurring compound involved in removing damaged cells.
"One surprising finding of our study was that suppression of only two specific brain regions was sufficient to produce many of the hematopoietic defects caused by psychological stress," said study author Linjia Jiang.
The researchers found that alterations in gut bacteria and reduced production of spermidine played a crucial role in transmitting stress-related signals from the brain to the bone marrow.
The team plans to investigate whether similar biological mechanisms exist in humans and how psychological stress affects neural circuits in different diseases.
They also intend to explore whether interventions targeting the gut microbiome or bone marrow could help improve immune function during ageing or prolonged periods of stress.
According to the researchers, the findings provide a framework for developing new strategies to reduce immune ageing and stress-related immune dysfunction.
"Our findings raise the possibility that managing psychological stress may not only improve mental well-being but also help preserve immune function and promote healthy ageing," Jiang said.