microRNA-146b improves intestinal injury in mouse colitis by activating NF-kB and improving epithelial barrier function

Aim: The precise role of microRNAs in inflammatory disease has been less clear. The present study investigated the effect of microRNA (miR-146b) on improving intestinal inflammation. Methods: The microRNA profile in IL-10-deficient mice was examined using microRNA arrays and miR-146b was selected for the following experiments. The expression vectors containing either the whole sequence of miR-146b or its siRNA were intraperitoneally administered to the dextran sulfate sodium (DSS)-induced colitis mouse. Results: The overexpression of miR-146b activated the NF-kB pathway, improved the epithelial barrier function, relieved intestinal inflammation in the DSS-induced colitis mice, and improved the survival rate of mice with lethal colitis. Furthermore, this amelioration of the intestinal inflammation by miR-146b was negated by the inhibitor for NF-kB pathway. Conclusion: The modulation of miR-146b expression is a potentially useful therapy for the treatment of intestinal inflammation through the activation of the NF-kB pathway. Mice: The present studies were approved by the Institutional Animal Care and Use Committee of the Asahikawa Medical College. C57BL/6 and IL-10-/- mice were purchased from Sankyo Labo Service Co., Inc. (Tokyo, Japan) and Jackson Laboratories (Bar Harbor, ME), respectively. Large intestines with or without treatments were removed, rinsed with saline, and the epithelium was gently sheared off with glass slides for protein determination. microRNA arrays: RNA was extracted from the large intestines of mice with Trizol and then was immediately frozen in liquid nitrogen. Next, the microRNA expression profiles of large intestine in wild-type and IL-10-deficient mouse were investigated using the mirVanaTM miRNA bioarray (Filgene, Inc., Japan). Any more than 2-fold differences were considered to indicate a significant change.