Background <p>Intestinal fibrosis is a serious complication of Crohn’s disease (CD), often resulting from chronic inflammation. However, the precise mechanisms through which inflammation induces intestinal fibrosis remain inadequately elucidated.</p> Methods <p>A comprehensive single-cell atlas of full-thickness CD, provided by Dr. Florian Rieder, was subjected to reanalysis. Our study used a DSS-induced chronic colitis model in both wild-type (WT) and <i>Areg</i>^{<i>−/−</i>} mice. Additionally, a CD45RB^hi CD4⁺ T cell adoptive transfer model involving WT and <i>Areg</i>^{<i>−/−</i>} Treg cells (Tregs) was used. The expressions of AREG in CD with or without intestinal fibrosis, Tregs and human intestinal myofibroblasts (MFs) were determined. The effect of AREG on proliferation/migration/activation in human intestinal MFs was determined.</p> Results <p>Several types of cells were differentially expressed between stricture and non-stricture CD. Among T cells, Tregs accounted for a larger proportion and were significantly increased in stenotic tissues of stricture CD. Although DSS-induced colitis was more severe in <i>Areg</i>^{<i>−/−</i>} mice, which developed less severe intestinal fibrosis compared with WT mice. The transfer of <i>Areg</i>^{<i>−/−</i>} Tregs resulted in less severe fibrosis in <i>Rag</i>^{<i>−/−</i>} mice than WT Tregs. Moreover, TGF-β stimulated AREG expression in Tregs and human intestinal MFs via activation of Smad3.</p> Conclusion <p>These findings demonstrated that AREG derived from Tregs and human intestinal MFs, induced by TGF-β, amplifies intestinal fibrotic reactions in experimental colitis as well as in human CD patients. Thus, the TGF-β-Smad3-AREG pathway could be a potential therapeutic target for treating fibrosis in CD.</p>