Dr Maria Vazquez–Roquefroom and colleagues from Florida, USA performed a randomized controlled 4-week trial of a gluten-containing diet or fluten-free diet in 45 patients with IBS-D.
Genotype analysis was performed for HLA-DQ2 and HLA-DQ8.
The research team randomized a gluten-containing diet, and 23 patients were placed on the gluten-free diet.
The research team measured bowel function daily, small-bowel and colonic transit, mucosal permeability, and cytokine production by peripheral blood mononuclear cells after exposure to gluten and rice.
The researchers collected rectosigmoid biopsy specimens from 28 patients, analyzed levels of messenger RNAs encoding tight junction proteins, and performed H&E staining and immunohistochemical analyses.
Subjects on the gluten-containing diet had more bowel movements per day.
The gluten-containing diet had a greater effect on bowel movements per day of HLA-DQ2/8–positive than HLA-DQ2/8–negative patients.
|Gluten-containing diet effects on expression were greater in HLA-DQ2/8–positive patients|
The gluten-containing diet was associated with higher small-bowel permeability.
The team noted small-bowel permeability was greater in HLA-DQ2/8–positive than HLA-DQ2/8–negative patients.
The team of doctors observed no significant differences in colonic permeability were observed.
Patients on the gluten-containing diet had a small decrease in expression of zonula occludens 1 in small-bowel mucosa, and significant decreases in expression of zonula occludens 1, claudin-1, and occludin in rectosigmoid mucosa.
The efects of the gluten-containing diet on expression were significantly greater in HLA-DQ2/8–positive patients.
The gluten-containing diet vs the gluten-free diet had significant effects on transit or histology.
The researchers examined that peripheral blood mononuclear cells produced higher levels of interleukin-10, granulocyte colony-stimulating factor, and transforming growth factor-α in response to gluten than rice.
Dr Vazquez–Roquefroom's team concluded, "Gluten alters bowel barrier functions in patients with IBS-D, particularly in HLA-DQ2/8–positive patients."
"These findings reveal a reversible mechanism for the disorder."