Expression of the anti-fibrotic regulator Dkk-1 is reduced in both human and/or animal models of fibrosis, including SSc skin, pulmonary fibrosis, liver cirrhosis, and fibroblasts (Akhmetshina et al., 2012; Dees et al., 2014; Henderson et al., 2021). This evidence concerns the gene DKK1 and systemic sclerosis.