METTL3 overexpression aggravates LPS-induced cellular inflammation in mouse intestinal epithelial cells and DSS-induced IBD in mice

The inflammatory bowel diseases (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic inflammatory disorders of the intestine. Dysregulated cytokine secretion and signal transduction mechanisms via intestinal epithelial cells are involved in IBD pathogenesis, in which the transcription factor NF-κB plays a critical role. In this study, METTL3, which plays a key role in inflammation regulation, has been recognized significantly up-regulated in IBD samples, DSS-induced IBD mice, and LPS-treated MODE-K cells. Within LPS-treated MODE-K cells, METTL3 knockdown promoted cell viability, inhibited cell apoptosis, decreased apoptotic caspase3/9 cleavage, and decreased the levels of proinflammatory cytokines (IL-1β, TNF-α, IL-6, and IL-18) and inflammatory enzymes (COX-2 and iNOS). Under the same conditions, METTL3 knockdown inhibited, whereas METTL3 overexpression promoted p65 phosphorylation in MODE-K cells; NF-κB inhibitor JSH-23 partially abolished the promotive effects of METTL3 overexpression upon p65 phosphorylation. Consistently, the effects of METTL3 overexpression upon LPS-stimulated MODE-K cells were partially abolished by JSH-23. Lastly, METTL3 knockdown in DSS-induced IBD mice significantly ameliorated DSS-induced IBD and inhibited DSS-induced p65 phosphorylation. In conclusion, METTL3 overexpression aggravates LPS-induced cellular inflammation in mouse intestinal epithelial cells and DSS-induced IBD in mice. The NF-κB signaling might be involved, and the regulatory mechanism remains to be investigated in our future study.