SPP1 and COVID-19: As hypothesized, our findings indicate that MAFB knockdown in nonstimulated M-MØ leads to diminished expression of the markers that best define the pathogenic profibrotic macrophage subsets in severe COVID-19 (CCL2, LGMN, CD163, SPP1) (39, 48, 49), whose encoding genes contain functional MAFB-binding sites, and it leads to reduced expression of genes coding for various chemokines and other COVID-19 severity biomarkers (e.g., CCL2, CXCL10, SPP1, CCL4, CCL5, CCL7, CD16, CXCL1, CXCL3, CXCL8, CXCL12, HAVCR2, IL2RA, IL10, IL18) (61, 64, 85–96).