Furthermore, DBC1 enhanced the differentiation of myocardial Treg cells into the ST2<sup>hi</sup>Areg<sup>hi</sup> subgroup in DCM through the HIF-1α-PPAR-γ axis.<h4>Conclusion</h4>Our current investigation shows that the DBC1-HIF-1α-PPAR-γ axis promotes the differentiation of myocardial Treg cells into the ST2<sup>hi</sup>Areg<sup>hi</sup> pro-fibrotic subgroup, which drives maladaptive myocardial fibrosis and cardiac dysfunction via paracrine secretion of Areg in DCM mice. This evidence concerns the gene CCAR2 and familial dilated cardiomyopathy.