SPP1 and idiopathic pulmonary fibrosis: A pro-fibrotic macrophage phenotype (CD163/LGMN-Mp), expressing high levels of SPP1, recently identified in severe COVID-19 ARDS and IPF (idiopathic pulmonary fibrosis), was absent from CART-BAL, sarcoidosis and HC BALs [26, 30, 33] (Supplementary Fig. 8A–C).