Bacteria Pass More Freely Through Colon in Women With IBS

Bacteria like Escherichia coli HS and Salmonella typhimurium are able to pass more freely through the colonic epithelium tissues of patients with irritable bowel syndrome (IBS) vs individuals without the condition, according to a recent study. Mast cells and vasoactive intestinal polypeptides (VIP) were found to facilitate this passage.

It has been established that IBS is associated with intestinal dysbiosis. Additionally, symptoms of IBS are known to develop after gastroenteritis. However, less is known about the role of mast cells and VIP in barrier regulation of the colonic epithelium in patients with IBS vs healthy individuals.
_____________________________________________________________________________________________________________

RELATED CONTENT
Could Probiotics Improve Depression and Anxiety Symptoms in IBS Patients?
IBS Patients May Benefit from a Low FODMAP Diet
_____________________________________________________________________________________________________________

In their study, the researchers compared 32 women with IBS with 15 age-matched healthy controls. The colon biopsies of all women studied were mounted in Ussing chambers, and the numbers of fluorescently labeled E coli HS and S typhimurium that passed from the mucosal side to the serosal side of the tissue were measured.

Results indicated that greater amounts of E coli HS and S typhimurium had passed through the epithelium in the biopsies of patients with IBS vs those of controls. Transmission electron microscopy analyses demonstrated that bacteria had crossed the epithelium only through the transcellular route. However, the passage of bacteria through the epithelium had decreased in the biopsies of both patients with IBS and controls after antibodies against VPACs or ketotifen were added.

The researchers noted that plasma samples from patients with IBS had shown higher levels of VIP compared with those of controls. Biopsies from patients with IBS had demonstrated higher levels of tryptase, more mast cells, and a higher percentage of mast cells that express VPAC1 than those of controls.

Adding S typhimurium significantly reduced levels of occludin in the biopsies of patients with IBS. However, the subsequent addition of ketotifen significantly reversed this effect.

“We found that colonic epithelium tissues from patients with IBS have increased translocation of commensal and pathogenic live bacteria compared with controls,” the researchers concluded. “The mechanisms of increased translocation include [mast cells] and VIP.”

—Christina Vogt

Reference:

Bednarska O, Walter SA, Casado-Bedmar M, et al. VIP and mast cells regulate increased passage of colonic bacteria in patients with irritable bowel syndrome [Published online July 12, 2017]. Gastroenterology.  http://dx.doi.org/10.1053/j.gastro.2017.06.051.