Researchers Find Biological Mechanism That Causes Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a condition that affects the colon and it is estimated that up to 20% of the world’s population experiences it. IBS can cause intense stomach pain or discomfort after eating, with certain foods also triggering symptoms like bloating and abnormal bowel habits, including diarrhoea or constipation.

According to Science Daily, some IBS sufferers experience relief when they follow certain elimination diets — for example, going gluten-free — but it is largely unknown why this works as many people with IBS aren’t actually allergic to the foods in question or have any conditions like coeliac disease.

In order to explore this condition which affects so many people but doesn’t have any tangible treatment, scientists from research university KU Leuven in Belgium explored the biological mechanisms which can cause IBS.

“Very often these patients are not taken seriously by physicians, and the lack of an allergic response is used as an argument that this is all in the mind, and that they don’t have a problem with their gut physiology,” said Professor Guy Boeckxstaens, a gastroenterologist at KU Leuven and lead author of the new research. “With these new insights, we provide further evidence that we are dealing with a real disease.”

In a series of clinical studies, Professor Boeckxstaens and his team found that a mechanism that connects certain foods with the activation of the cells that release histamine can lead to pain and discomfort. The researchers found that blocking the histamine actually improved the IBS condition in many people.

When an intestine is healthy, the immune system doesn’t react to foods. In order to understand why people with IBS do experience reactions, Professor Boeckxstaens explored how the presence of infection alongside particular foods could sensitise the immune system to that food.

This idea was carried out in studies with mice, who were infected with a stomach bug while also being fed ovalbumin — a protein found in egg white that is commonly used in experiments as an antigen, which is a molecule that provokes an immune response. Once the mice had recovered from the infection, they were fed ovalbumin again, in order to see how their immune system responded.

According to Science Daily, “the results were affirmative: the ovalbumin on its own provoked mast cell activation, histamine release, and digestive intolerance with increased abdominal pain. This was not the case in mice that had not been infected with the bug and received ovalbumin.”

Interestingly, the reaction only occurred in the part of the intestine where the infection had disrupted bacteria. The researchers used these findings to explore whether people with IBS would react similarly and, they found that when 12 IBS sufferers were injected with antigens that usually provoke reactions (like gluten, wheat, soy and cow milk) into their intestine wall, they exhibited similar outcomes as the mice.

While further research is needed in this area, Professor Boeckxstaens noted that this study showed the mechanism discovered by the researchers has “clinical relevance”.

“But knowing the mechanism that leads to mast cell activation is crucial, and will lead to novel therapies for these patients,” he said. “Mast cells release many more compounds and mediators than just histamine, so if you can block the activation of these cells, I believe you will have a much more efficient therapy.”

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