Aberrant mucosal lymphocyte number and subsets in the colon of post-infectious irritable bowel syndrome patients

Abstract

Background. Irritable bowel syndrome (IBS) is characterized by chronic abdominal symptoms such as pain, discomfort, and altered bowel habits. A subset of IBS patients, denoted as post-infectious IBS (PI-IBS) patients, develop symptoms after an enteric infection. Distinct abnormalities in the gut mucosa, including mucosal inflammation, have been proposed to contribute to or be the cause of PI-IBS. This study investigated lymphocyte subsets in PI-IBS patients compared to healthy controls. Materials and methods. Ten PI-IBS patients and nine healthy controls participated. All PI-IBS patients met the Rome III diagnostic criteria for IBS and reported sustained symptoms at least 1 year after an episode of acute gastroenteritis. Intraepithelial lymphocytes and lamina propria lymphocytes (LPLs), isolated from mucosal tissue samples, were stained and analyzed for a comprehensive set of cell markers using flow cytometry. Results. The number of LPLs in PI-IBS was significantly increased compared to those in healthy controls (p < 0.05). PI-IBS patients showed significantly increased proportions of CD45RO⁺ CD4⁺ activated/memory T cells (p < 0.05) and double-positive CD4⁺ CD8⁺ cells (p < 0.05), respectively, in the lamina propria. The number of CD19⁺ LPLs was decreased in PI-IBS patients compared to healthy controls (p < 0.001). Conclusion. This study presents new evidence that PI-IBS is associated with a sustained aberrant mucosal immune response and support future studies of anti-inflammatory or immune-modulating treatments in these patients.

Key Words::

• cell biology
• gastrointestinal
• infections
• health economy
• immunology

Acknowledgment

The authors thank Elisabeth Tina (Clinical Research Centre, Örebro University Hospital) and Kristina Elgbratt (School of Medicine and Health, Örebro University) for their support with the flow cytometry technique. Founding: Johanna Sundin is supported by a grant from the Medical Faculty, Örebro University.

Declaration of interest: The authors are not aware of financial conflict with the subject matter or material discussed in this article with any of the authors or their academic institutions or employers.