COL1A1 and pulmonary fibrosis: From another perspective, Chi3L1 deficiency also obviously reduced the extent of fibrosis and hydroxyproline content in the lungs of BLM‐SSC mice (Figure S8A,B, Supporting Information).[33] ELISA and qPCR analyses revealed a decline in Col1A1 expression in the lungs of BLM‐SSc KO mice compared with BLM‐SSc WT mice, suggesting lung fibrosis mitigation (Figure S8C,D, Supporting Information).