CCL4 and systemic sclerosis: To determine whether the NL-specific elevations in SPP1 and CCL4 were also a feature of lesional systemic sclerosis skin–derived myeloid cells, we performed scRNA-seq on skin biopsy samples obtained from 4 patients with systemic sclerosis (aka scleroderma) and 3 healthy controls (in total, 2,777 myeloid cells were sequenced).