Investigators have documented structural abnormalities in the small bowel of patients with irritable bowel syndrome (IBS). The findings could fundamentally change the way the disease is perceived.
“Given the visible structural lesions in the small bowel of IBS patients, I think it is accurate to say that we can no longer call IBS a functional bowel disorder,” said principal investigator Dr Julia Liu, assistant professor at the University of Alberta’s Center of Excellence for Gastrointestinal Inflammation and Immunity Research in Canada.
Using probe-based confocal laser endomicroscopy (pCLE) in 17 patients with IBS and 18 healthy controls, Dr Liu and her colleagues found that small bowel epithelial cell loss was five times higher in patients with IBS. A fluorescein-aided pCLE was conducted in patients during routine endoscopy, whereby they documented the epithelial gap density – an indicator of epithelial cell loss – in the small intestine.
Of the 16 patients with IBS, 12 had diarrhea-predominant IBS and four had constipation-predominant IBS. All met the diagnostic criteria for functional gastrointestinal disorders.
Apart from the paradigm-shifting nature of the findings, Dr Liu believes the structural epithelial abnormalities that her team documented can be used to diagnose IBS.
She acknowledged, however, that “this was a pilot study, and we need to confirm the diagnostic potential of pCLE-detected epithelial gaps in a large, prospective, multicentre study with many more patients.”
Dr Lucinda Harris, associate professor of medicine in the Department of Gastroenterology and Hepatology at the Mayo Clinic College of Medicine in the United States, and an IBS expert who was not involved in the study, cautioned that the results need to be replicated before conclusions can be drawn.
“[CLE] is a relatively new technique of uncertain significance for this indication,” she said. She pointed out that most of the study subjects had diarrhea-predominant IBS, meaning the findings may not be generalisable to all IBS subtypes.
“IBS is a diverse disorder with several different theories of pathogenesis,” said Dr Harris. “The role of barrier function and the meaning of this difference in epithelial gap may certainly fit as another physiologic explanation, particularly in IBS patients with a post-infectious etiology with diarrhea, but may not explain the disorder in all subtypes. However, it certainly does warrant further study.”