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Lactose and Fructo-oligosaccharides Increase Visceral Sensitivity in Mice via Glycation Processes, Increasing Mast Cell Density in Colonic Mucosa.

BACKGROUND AND AIMS
Irritable bowel syndrome (IBS) is characterized by abdominal pain, bloating, and erratic bowel habits. A diet low in fermentable oligo-, di-, mono-saccharides and polyols (FODMAPs) can reduce symptoms of IBS, possibly by reducing microbial fermentation products. We investigated whether ingestion of FODMAPs can induce IBS-like visceral hypersensitivity mediated by fermentation products of intestinal microbes in mice.


METHODS
C57Bl/6 mice were gavaged with lactose, with or without the anti-glycation agent pyridoxamine, or saline (controls) daily for 3 weeks. A separate group of mice were fed a diet containing fructo-oligosaccharides, with or without pyridoxamine in drinking water, or a normal chow diet (controls) for 6 weeks. Feces were collected and analyzed by 16S rRNA gene sequencing and bacterial community analyses. Abdominal sensitivity was measured by electromyography and mechanical von Frey filament assays. Colon tissues were collected from some mice and analyzed by histology and immunofluorescence, to quantify mast cells and expression of advanced glycosylation end-product specific receptor (AGER).


RESULTS
Mice gavaged with lactose or fed fructo-oligosaccharides had increased abdominal sensitivity compared with controls, associated with increased numbers of mast cells in colon and expression of the receptor for AGER in proximal colon epithelium. These effects were prevented by administration of pyridoxamine. Lactose and/or pyridoxamine did not induce significant alterations in the composition of the fecal microbiota. Mass spectrometric analysis of carbonyl compounds in fecal samples identified signatures associated with mice given lactose or fructo-oligosaccharides vs controls.


CONCLUSION
We found that oral administration of lactose or fructo-oligosaccharides to mice increases abdominal sensitivity, associated with increased numbers of mast cells in colon and expression of AGER; these can be prevented with an anti-glycation agent. Lactose and/or pyridoxamine did not produce alterations in fecal microbiota of mice. Our findings indicate that preventing glycation reactions might reduce abdominal pain in patients with IBS with sensitivity to FODMAPs.