MARCO and pulmonary fibrosis: This attenuated pulmonary fibrosis in aged mice shown by decreased Masson staining and Ashcroft scores, reduced tissue levels of HYP and reduced expression levels of fibrogenic protein genes including Col1a1, Timp1, and α-SMA, which was similar to the MARCO blockade by anti-MARCO treatment (Fig. 6A and B), further confirming the critical role of MARCO+AMs in promoting pulmonary fibrosis in aged mice.