An IRF1-dependent Pathway of TNF alpha-induced Shedding in Intestinal Epithelial Cells

摘要

Background Shedding of intestinal epithelial cells IECs is a potent cause of barrier loss which plays an important role in the pathogenesis of inflammatory bowel disease IBD. TNF alpha can induce IEC shedding, but little is known about this process. Methods To investigate the molecular mechanism regulating IEC shedding, mice lacking interferon regulatory factor1 IRF1, caspase-3, or gasdermin E GSDME and their control wild-type WT littermates were intravenously injected with tumour necrosis factor alpha TNF alpha to establish an IEC shedding model. A dual-luciferase reporter assay and a chromatin immunoprecipitation assay were used to determine the role of IRF1 in regulating caspase-3 expression. Results TNF alpha administration induced obvious IEC shedding in WT mice, but IRF1(-/-) and caspase-3(-/-)mice were completely protected from TNF alpha-induced IEC shedding. As a critical transcription factor, IRF1 was found to be required for caspase-3 expression in IECs by binding to IRF1-binding sites in the caspase-3 promoter. In WT mice, plasma membrane integrity was disrupted in shed IECs; these cells were swollen and contained GSDME-N terminal NT fragments which are responsible for the induction of pyroptosis. However, in GSDME(-/-) mice, plasma membrane integrity was not disrupted in shed IECs, which were not swollen and did not contain GSDME-NT, indicating that GSDME converted TNF alpha-induced IEC shedding into a pyroptotic cell death process. In addition, IRF1 deficiency resulted in decreases in mucosal inflammation and mucosal bacteria levels in TNF alpha-challenged colons. Conclusions IRF1 deficiency maintains intestinal barrier integrity by restricting TNF alpha-induced IEC shedding.