scRNAseq analysis of BALF cells from COVID-19 patients indicated a predominance of macrophages (100, 101), where ENPP2 mRNA expression was detected in monocyte-derived alveolar macrophages (Mo-AMs) (61), that have been shown to drive the development of BLM-induced pulmonary fibrosis in mice (105). Here, ENPP2 is linked to pulmonary fibrosis.