Inflammatory bowel disease, often called IBD, is a long-term condition that causes inflammation in the digestive system. It includes diseases such as Crohn’s disease and ulcerative colitis.
People with IBD often suffer from abdominal pain, diarrhea, and fatigue. Modern treatments can reduce inflammation and help patients reach what doctors call remission, which means the active inflammation is under control.
However, many patients still continue to experience uncomfortable symptoms even after the inflammation has gone away. These ongoing symptoms are often similar to irritable bowel syndrome, or IBS, a condition that affects how the gut moves and functions.
For many years, doctors did not fully understand why these symptoms continue after the visible inflammation has resolved. A new study led by Dr. Milena Bogunovic at the Icahn School of Medicine at Mount Sinai provides an important explanation.
The research was published in the Journal of Experimental Medicine and offers new insight into how inflammation can leave long-lasting effects on the gut.
To understand the study, it helps to know how the digestive system is controlled. Inside the walls of the gut is a complex network of nerve cells called the enteric nervous system.
This system contains more than 100 million neurons and is sometimes called the “second brain.” It controls many important functions such as digestion, movement of food, and coordination of muscle contractions in the intestines.
In a healthy gut, these neurons are arranged in an organized way. They send clear and coordinated signals to the muscles, helping food move smoothly through the digestive tract. However, the new study found that inflammation can disturb this system in a lasting way.
The researchers discovered that during inflammation, the nerve cells in the gut become activated and start sending signals to immune cells known as monocytes.
These monocytes move into the nervous system in the gut and develop into cells called macrophages. Normally, macrophages help repair tissue, but when too many of them gather in one place, they can cause problems.
In this case, the large number of macrophages leads to changes in how the nerve cells are arranged. The study showed that the normal, neat structure of the enteric nervous system becomes disorganized. Some areas lose nerve cells, while other areas develop clusters of tightly packed neurons with irregular connections.
This disorganization affects how the gut muscles behave. Instead of working in a smooth and coordinated way, the muscles contract in an uncoordinated manner. This can lead to symptoms such as pain, bloating, and irregular bowel movements, even when inflammation is no longer present.
The study also found that inflammation can create a low-oxygen environment in the gut. This condition, known as hypoxia, places stress on the neurons. In response, the neurons can activate a protective pathway that helps them survive. This pathway reduces the attraction of immune cells and helps maintain the normal structure of the nervous system.
Importantly, when this protective response is activated early, it can prevent the long-term damage to the enteric nervous system. This suggests that early treatment aimed at supporting this response could help reduce ongoing symptoms in patients with IBD.
Another surprising finding was that the gut may be able to generate new neurons. Traditionally, scientists believed that neurons are fixed at birth and gradually decline over time.
However, this study showed that new neurons can form in the gut after inflammation. These new neurons, however, may not be properly organized, contributing to the dysfunction.
Overall, this study provides a new understanding of why some patients continue to suffer from gut symptoms even after inflammation has been treated. It shows that the problem is not just inflammation itself, but the lasting changes it causes in the nervous system of the gut.
In analysing these findings, it is clear that the study shifts the focus from inflammation alone to long-term structural changes in the gut. It highlights the importance of early intervention and suggests new treatment approaches that protect nerve cells rather than only reducing inflammation.
While the research is based on animal models and more studies are needed in humans, it opens a promising path toward better management of IBD and related conditions.
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For more information about gut health, please see recent studies about Navigating inflammatory bowel disease (IBD) with diet and results showing that Mycoprotein in diet may reduce risk of bowel cancer and improve gut health.
Source: Icahn School of Medicine at Mount Sinai.
