AUTHOR=Zhu Fengting , Yang Taotan , Ning Mengmeng , Liu Yang , Xia Wei , Fu Yan , Wen Ting , Zheng Mei , Xia Ruilong , Qian Ran , Li Yang , Sun Minxuan , Liu Jianping , Tian Li , Zhou Qian , Yu Xin , Peng Changgeng 

TITLE=MiR-146a alleviates inflammatory bowel disease in mice through systematic regulation of multiple genetic networks

JOURNAL=Frontiers in Immunology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1366319

DOI=10.3389/fimmu.2024.1366319

ISSN=1664-3224

ABSTRACT=<sec><title>Introduction</title><p>Inflammatory bowel disease (IBD) is a chronic disease involving multiple genes, and the current available targeted drugs for IBD only deliver moderate efficacy. Whether there is a single gene that systematically regulates IBD is not yet known. <italic>MiR-146a</italic> plays a pivotal role in repression of innate immunity, but its function in the intestinal inflammation is sort of controversy, and the genetic regulatory networks regulated by miR-146a in IBD has not been revealed.</p></sec><sec><title>Methods</title><p>RT-qPCR was employed to detect the expression of <italic>miR-146a</italic> in IBD patients and in a mouse IBD model induced by dextran sulfate sodium (DSS), and then we generated a <italic>miR-146a</italic> knock-out mouse line with C57/Bl6N background. The disease activity index was scored in DSS-treated miR-146a deficiency mice and their wild type (<italic>WT</italic>) littermates. Bulk RNA-sequencing, RT-qPCR and immunostaining were done to illustrate the downstream genetic regulatory networks of <italic>miR-146a</italic> in flamed colon. Finally, the modified <italic>miR-146a</italic> mimics were used to treat DSS-induced IBD in <italic>miR-146a</italic> knock-out and <italic>WT</italic> IBD mice.</p></sec><sec><title>Results</title><p>We showed that the expression of <italic>miR-146a</italic> in the colon was elevated in dextran sulfate sodium (DSS)-induced IBD mice and patients with IBD. DSS induced dramatic body weight loss and more significant rectal bleeding, shorter colon length, and colitis in <italic>miR-146a</italic> knock-out mice than <italic>WT</italic> mice. The miR-146a mimics alleviated DSS-induced symptoms in both <italic>miR-146a<sup>-/-</sup></italic> and <italic>WT</italic> mice. Further RNA sequencing illustrated that the deficiency of <italic>miR-146a</italic> de-repressed majority of DSS-induced IBD-related genes that cover multiple genetic regulatory networks in IBD, and supplementation with <italic>miR-146a</italic> mimics inhibited the expression of many IBD-related genes. Quantitative RT-PCR or immunostaining confirmed that <italic>Ccl3, Saa3, Csf3, Lcn2, Serpine1, Serpine2</italic>, MMP3, MMP8, MMP10, IL1A, IL1B, IL6, CXCL2, CXCL3, S100A8, S100A9, TRAF6, P65, p-P65, and IRAK1 were regulated by miR-146a in DSS induced IBD. Among them, <italic>MMP3, MMP10, IL6, IL1B, S100A8, S100A9, SERPINE1, CSF3</italic>, and <italic>IL1A</italic> were involved in the active stage of IBD in humans.</p></sec><sec><title>Discussion</title><p>Our date demonstrated that miR-146a acts as a top regulator in C57/BL6N mice to systematically repress multiple genetic regulatory networks involved in immune response of intestine to environment factors, and combinatory treatment with <italic>miR-146a-5p</italic> and <italic>miR-146a-3p</italic> mimics attenuates DSS-induced IBD in mice through down-regulating multiple genetic regulatory networks which were increased in colon tissue from IBD patients. Our findings suggests that <italic>miR-146a</italic> is a top inhibitor of IBD, and that <italic>miR-146a-5p</italic> and <italic>miR-146a-3p</italic> mimics might be potential drug for IBD.</p></sec>