Co-culture systems were performed to analyze the effect of ST2<sup>hi</sup>Areg<sup>hi</sup> Treg cells on fibroblast behaviors.<h4>Results</h4>ST2<sup>+</sup>Treg subsets were increased in the hearts of DCM mice and exhibited increased Areg expression. This evidence concerns the gene AREG and familial dilated cardiomyopathy.