Figure 1.

Cytokine Storm in Response to COVID-19. The SARS-COV2 attaches to lung epithelial cells and alveolar macrophages by the angiotensin-converting enzyme (ACE2). ACE2 down-regulation and the loss of ACE2 from the endothelium enhance inflammation and vascular permeability by the induction of ROS and TNF-α. Pro-inflammatory cytokine and chemokine activated more neutrophils and macrophages and activated T-cell and excessive immune response and started the cytokine storm. Eventually these events may damage to the respiratory system and advance the disease towards ARDS or multi-organ dysfunction.