Ingestion of low dose pyroglutamyl leucine improves dextran sulfate sodium-induced colitis and intestinal microbiota in mice.

Inflammatory bowel diseases (IBD) are based on chronic inflammation in the gastrointestinal tract. We previously found anti-inflammatory peptide pyroGlu-Leu in the enzymatic hydrolysate of wheat gluten. The objective of present study is to elucidate improvement of colitis by oral administration of pyroGlu-Leu in an animal model. Acute colitis was induced by dextran sulfate sodium (DSS), and various concentrations of pyroGlu-Leu were administrated by oral gavage for 7 days. A dose of 0.1 mg/kg body weight/day showed the most significant improvement. The pyroGlu-Leu concentration was significantly increased 24 h after oral administration both in the small intestine and the colon compared with the baseline. It was 20-fold higher in the small intestine than the colon. Administration of pyroGlu-Leu normalized population of Bacteroidetes and Firmicutes in the colon. These results indicate that pyroGlu-Leu has a potential therapeutic effect against IBD at a practical dose.