It is noteworthy that MFAP5hi fibroblasts expressed higher SFRP, PCOLCE2, and CD55 than the skin SFRP2/DPP4 fibroblasts, while WIF1hi fibroblasts did not express SFRP2. In addition, myofibroblasts underwent the greatest phenotypic changes and upregulated the expression of collagen and other pro-fibrotic genes in SSc-ILD, which was pivotal to the pathologic mechanisms of fibrosis in SSc-ILD (Valenzi et al., 2019). Here, DPP4 is linked to systemic sclerosis.