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

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.

Automated summary

IRF1 deficiency maintains intestinal barrier integrity by restricting TNF alpha-induced IEC shedding.