Crosstalk between circRNAs and the classic signaling pathways in IBD.

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disorder of the gastrointestinal tract with a complex aetiology involving genetic, environmental (such as diet/lifestyle), and microbiota factors. The exact pathogenesis of IBD remains unclear, and current therapies show limited effectiveness. Circular RNAs (circRNAs) are a novel class of noncoding RNAs that have been implicated in the regulation of various biological processes. Many circRNAs show specific expression profiles in IBD patients and play important roles in IBD pathogenesis through different signalling pathways, such as the Janus kinase/signal transducer and activator of transcription (JAK/STAT) and nuclear factor-κB (NF-κB) pathways. Although research on circRNAs in IBD is still in its early stages, many circRNAs have emerged as potential diagnostic, prognostic biomarkers, and therapeutic targets for IBD. Here, we summarize the molecular functions and underlying mechanisms of circRNAs in IBD and discuss current challenges and future perspectives for clinical applications.