CHI3L1 and systemic sclerosis: Moreover, the skin cells of HCs barely secrete Chi3L1; however, in SSc, particularly in its early stages, endogenous Chi3L1 secretion occurs, although the specific source remains unclear.[21, 49] Based on clues from transcriptome data, our results confirmed that Chi3L1 was predominantly expressed by basal cells among all cells derived from the skin.