Effects of IRW and IQW on Oxidative Stress and Gut Microbiota in Dextran Sodium Sulfate-Induced Colitis.

BACKGROUND/AIMS: There are known links between inflammatory bowel disease (IBD) and changes in the microbiota of the gut and inflammation and oxidative stress. In this study, a colitis model induced by dextran sodium sulfate (DSS) in mice is used to evaluate whether the presence of bioactive peptides IRW (Ile-Arg-Trp) and IQW (Ile-Gln-Trp) peptides is advantageous.

METHODS: The mice were arbitrarily assigned to the following four groups: (i) control (untreated), (ii) dextran sodium sulfate (DSS) treated, (iii) IRW-DSS treated, and (iv) IQW-DSS treated. For 7 days, the control group subjects had unrestricted access to untreated drinking water, whereas the drinking water supplied to the subjects in the DSS, IRW-DSS, and IQW-DSS groups during this period consisted of 5% DSS solution. The colonic lesions were scored after hematoxylin and eosin staining. Serum antioxidant capacity was analyzed by 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS) radical cation decolorization test and the microbiota in the colonic contents were sequenced by HiSeq2500 PE250.

RESULTS: The presence of DSS reduced daily weight gain, enhanced histopathology scores, and inhibited antioxidant enzyme expression. Superoxide dismutase, catalase, and glutathione peroxidase activities in the DSS-induced colitis model were significantly enhanced (P < 0.05) in the presence of dietary IRW and IQW. Furthermore, the Simpson index was significantly increased (P < 0.05) in the presence of dietary IRW and IQW compared to the control group. IRW and IQW increased the abundance of Coprococcus_1, Ruminococcaceae_UCG-014, and Desulfovibrio compared to the control group and DSS group. Furthermore, IQW decreased the abundance of Bacteroides in relation to the control group, but increased Parabacteroides. In addition, IRW increased the level of Anaerotruncus, Oscillibacter, and Ruminiclostridium_9 compared to the control group.

CONCLUSION: This study concludes that the presence of IRW or IQW can mitigate DSS-induced oxidative stress by improving the activities of antioxidant enzymes, increasing intestinal microbial diversity and enhancing the abundance of gut microbiota, which may help maintain the homeostasis of host health and microenvironment in a DSS-induced mouse model, thus providing a potential further treatment for IBD patients.