CD55 and systemic sclerosis: SFRP2hi fibroblasts included three subpopulations: subpopulations expressing WIF1 and NKD2 (WIF+ fibroblasts, subcluster 3) and SLPI, PCOLCE2, and CD55 (PCOLCE+ fibroblasts, subcluster 1) found previously in normal skin (Figs. 2a and 3a), and a new subcluster of cells found mainly in SSc skin fibroblasts (PRSS23+ fibroblasts, subcluster 4; Figs. 2a and 4a).