In this study, it was shown step by step in mice that psychological stress stimulates glucocorticoid production via the hypothalamic-pituitary-adrenal cortex, that this stress hormone induces enteric glial cells to produce the protein CSF1, and that this protein in return stimulates monocytes to accumulate in the intestinal mucosa and produce the pro-inflammatory cytokine TNF. Through this mechanism, stress can cause colitis to become more severe in mice that develop intestinal inflammation.

In three different human research cohorts, including one from Maastricht UMC+ and Zuyderland MC, we could validated these findings in humans. This demonstrated the biological link between psychological stress and intestinal inflammation in humans as well. However, the described findings also raise new questions. For instance, this study shows that stress can worsen intestinal inflammation via glucocorticoids, while in daily practice; drugs like prednisone are actually used to treat intestinal inflammation in IBD. However, we also know that overuse of prednisone in patients with IBD can lead to an unfavorable course of inflammation. It is possible that the described mechanism plays a role here. Further research will need to provide further clarification.

 Psychological stress is a potential modulating factor of the immune system. People with psychological symptoms are more likely to develop IBD, both ulcerative colitis and Crohn's disease.

 We could demonstrate for inflammatory bowel disease (IBD), an association between acute psychological stress and subsequent flare-up of intestinal inflammation.

 Animal studies have demonstrated causality and unraveled the biological mechanism by which stress modulates intestinal inflammation. There is a relationship between stress and colitis in mice.

 Human cohort studies validated this and found that higher stress scores in people with IBD also led to a higher chance of IBD flare-ups in the months following the stress.

 Stress leads to the production of cortisol via the hypothalamic-pituitary-adrenal cortex, which activates glial cells in the enteric nervous system.

 Glial cells play a crucial role in the gut and trigger monocytes in the intestines to produce the pro-inflammatory cytokine TNF.

What is the impact of this research for Inflammatory Bowel Diseases (IBD) in your opinion?

This knowledge about the relationship between psychological stress and intestinal inflammation opens new doors for treatments of diseases like IBD. The biological mechanism not only opens doors for the development of non-pharmacological stress-reducing therapies for IBD. The neuroimmunological process is also interesting as a potential new target for future pharmacological therapies. The biological link between psychological stress and intestinal inflammation that we discovered has greatly increased our understanding about the relationship between psyche, nervous system and immune system. This can lead to new approaches to diseases like IBD.

Text: Danielle Vogt