Figure 2.

Schematic diagram showing the process by which the new coronavirus enters the human body and triggers an inflammatory response. ACE2 and TMPRSS2 play a decisive role in neo-coronavirus invasion. The major PRRs against viruses are present on the cytoplasmic and endosomal membranes of immune cells and recognize foreign viruses. After a series of processes, they finally produce transcription factors NF-κB and IFRs on the cell membrane. Next, they migrate to the nucleus and induce the expression of encoded cytokines and IFN-I and IFN-III, pro-inflammatory cytokines, and chemokines, which in turn accumulate large numbers of neutrophils. The secretion of neutrophils, cytokines, and chemokines promotes further accumulation of immune cells, producing an excessive inflammatory response or further triggering the cytokine storm mentioned below.