Stressed out? It could be one reason why your stomach hurts. Scientists at the Perelman School of Medicine at the University of Pennsylvania have made an exciting breakthrough in understanding the connection between stress and inflammation in the gastrointestinal (GI) tract. By studying animals, they have identified cells responsible for communication between the brain’s stress responses and inflammation in the gut.
This discovery could help explain why stress worsens symptoms of inflammatory bowel disease (IBD), a condition that affects around 1.6 million Americans.
IBD is characterized by inflammation in the GI tract, leading to symptoms such as persistent diarrhea, abdominal pain, and bloody stools. Prolonged inflammation can cause permanent damage. Current treatments for IBD include anti-inflammatory drugs, immune suppressants, dietary changes, and steroids.
“Until now, we didn’t know how the digestive system detects and responds to chronic stress, which clinicians have long observed can make IBD symptoms worse,” said Christoph Thaiss, Ph.D., an assistant professor of Microbiology and the senior author of the study, in a media release.
In their research, scientists found that mice with IBD experienced severe symptoms when exposed to stress, similar to humans. They traced the stress response signals to the adrenal cortex, which releases steroid hormones called glucocorticoids. These hormones activate the body’s stress response. Neurons and glial cells in the enteric nervous system (ENS), the semi-autonomous nervous system within the GI tract, responded to elevated levels of glucocorticoids. This suggests that they are the link between the brain’s perception of stress and intestinal inflammation.
Normally, glucocorticoids have an anti-inflammatory effect on the body. However, when glial cells in the ENS are exposed to these hormones for an extended period, such as during chronic stress, they attract white blood cells to the GI tract, leading to increased inflammation. Additionally, chronic stress disrupts the normal functioning of neurons in the ENS, which can result in impaired bowel movements and worsened IBD symptoms.
To validate their findings in humans, Thaiss and his colleagues analyzed data from the UK Biobank and a patient cohort from the IBD Immunology Initiative at Penn Medicine. They discovered that stress levels reported by patients with IBD correlated with the severity of their symptoms.
“This finding emphasizes the importance of psychological evaluations for IBD patients and informs treatment protocols,” said Maayan Levy, Ph.D., an assistant professor of Microbiology and co-senior author of the study. “Steroids are a common treatment for IBD flare-ups, but our research suggests that their effectiveness may be impaired in patients with IBD who experience chronic stress.”
The researchers believe further investigation into enteric glial cells is necessary to understand their role in various regulatory systems in the body, including the communication between the nervous and immune systems.
The study is published in the journal Cell.