We have known for a long time that chronic stress increases the inflammation typical of some intestinal diseases. A new study reveals how it does it.
That chronic stress is detrimental to health in general, and in particular to that of the intestine, has been known for some time: a study recently published in Cell clarifies the reason. According to the new work, some substances produced by the stressed brain manage to stimulate the immune cells of the intestine and cause inflammation. But they do it through a concatenation of steps that until now was not known.
Intestine on fire. Chronic inflammatory bowel diseases (in English “IBD”, Inflammatory Bowel Disease) such as Crohn’s disease and ulcerative colitis, are pathologies characterized by inflammation of the intestine that involve symptoms such as diarrhea, tiredness, abdominal pain and, in the most serious cases, rectal bleeding . The onset of these diseases is often following very stressful events, such as job loss or the end of a relationship. Mental health care is of great help in the management of these conditions, but it is often overlooked because all the attention is focused on pharmacological treatments.
Alarm message. Christoph Thaiss and microbiological colleagues at the University of Pennsylvania in Philadelphia have uncovered the molecular causes of this link. During peak stress levels, the brain sends signals to the adrenal glands, located on the top end of each kidney. These in response produce a particular class of chemicals, called steroid hormones glucocorticoids.
A precise chain of events. Thaiss and colleagues initially hypothesized that glucocorticoids directly stimulated the immune cells of the gut. But studies in mice have shown the existence of a number of ‘intermediate players’. In fact, the hormones in question act on the neurons of the intestine (the cells that are part of the enteric nervous system and which govern, for example, the movements of the intestinal smooth muscle) and on the cells that connect them, the glia cells.
Under the influence of glucocorticoids, some glial cells stimulate the immune cells of the intestine, which release inflammatory molecules as if to respond to the attack of a pathogen. But there is no external threat and the only effect of this “scaremongering” is increased inflammation. A second result of glucocorticoids is that they prevent immature nerve cells from fully developing. These neurons will then be less effective at controlling bowel movements – which can cause further digestive problems for those with IBD.
apparent contradiction. A paradoxical fact is that steroid hormones are often prescribed as a drug treatment for those suffering from ulcerative colitis or Crohn’s disease.
According to the authors of the study, what makes the difference is the period of exposure to these substances: supplied for a short time as in medicinal therapies they have an anti-inflammatory effect, while their chronic presence has the opposite effect, and causes inflammation.
Health starts from the brain. The research underlines the importance, for those suffering from chronic inflammatory bowel diseases, of implementing stress management strategies together with pharmacological treatments, to increase the effectiveness of the treatments. Furthermore, the authors point out, stress can also negatively affect pathologies affecting other organs, such as the lungs and the skin, perhaps following mechanisms similar to the one just found.