The Possible Role of Viruses in the Development of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder characterized by abdominal pain and changes in intestinal movements in the absence of structural or biochemical abnormalities. In spite of the high prevalence, its etiology is unknown, and there are no specific diagnostic laboratory tests.

In a case/control study, 36 biopsy samples taken from patients with IBS and 30 biopsy samples as control were obtained. Expression of Toll-like receptor 3 (TLR 3), Toll-like receptor 9 (TLR 9), and Retinoic acid-inducible gene I (RIG 1) in macrophages, lymphocytes, and plasma cells in terms of percentage and color intensity were evaluated by immunohistochemistry. The obtained data were statistically analyzed using Mann Whitney U and Chi-square tests.

The differences between percentage and intensity in the sample and control groups were significant for all three receptors in the epithelial cells. In plasma cells, the difference in TLR 3 and TLR 9 percentage was significant but not significant for RIG. However, in terms of intensity, it was not significant for any of them. In lymphocytes and macrophages, there was no significant difference for any of the receptors.

Since the expression of some virus sensing receptors on the different cell types of the intestine increases following infection, we concluded that IBS might be related to viral infections of the intestine. Future studies are needed to reveal the exact nature of the suspected viral agents. Some viruses producing gastroenteritis in humans, such as coronavirus, can be suspected.