REGγ Links Inflammation to Fibrosis in Post-Necrotizing Enterocolitis Intestinal Strictures by Activating TGF-β/Smad3 Signaling

Intestinal stricture affects 2.9-57% of necrotizing enterocolitis (NEC) cases, primarily involving the terminal ileum and colon. While inflammation-driven fibrosis underlies stricture development, key molecular mechanisms remain unclear. Upregulation of REGγ was previously observed in human NEC specimens and murine models, correlating with inflammation severity. Here, elevated REGγ in human strictures correlated with fibrotic severity. Single-cell RNA sequencing and immunofluorescence confirmed REGγ enrichment in fibroblasts. In vitro, REGγ silencing suppressed TGF-β1 or TNF-α-induced fibroblast activation, proliferation, and migration, accompanied by reduced Smad3 phosphorylation and nuclear translocation. Mechanistically, TNF-α enhanced REGγ transcription via NF-κB p65 binding to its promoter. NF-κB inhibition attenuated TNF-α-induced fibrotic responses, rescued by REGγ overexpression. In murine fibrosis models, REGγ deficiency reduced inflammation, collagen deposition, and p-Smad3. These findings establish REGγ as a key mediator of inflammation-fibrosis crosstalk in post-NEC intestinal strictures and a promising therapeutic target.