Fig. 1

Macrophage activation and its synergistic augmentation of inflammation in COVID-19. SARS-CoV-2 infects pneumocytes or enters macrophage. Infection-induced cell death promotes the release of damage signal molecules and inflammatory cytokines. Macrophages are activated upon inflammatory signal or viral genome entry then produce inflammatory cytokines and chemokines which recruit and activate T cells. Feedback inflammatory signals from T cells further activate macrophages. Synergistic augmentation of inflammation spread the entire lung and consequently systemic organ