SPP1 and pulmonary fibrosis: Genes downregulated in high-uncertainty IPF macrophages are associated with homeostatic functions of tissue-resident alveolar macrophages and lipid metabolism (PPARG, FABP4 and others)22,24,58, while upregulated genes are associated with extracellular matrix remodeling and scar formation in the context of lung fibrosis (SPP1, PLA2G7 and CCL2; Supplementary Tables 12 and 13 and Extended Data Fig. 9b,c)22,24,58.