Figure 10.

Proposed working model of ACE2 during SARS‐CoV‐2 infection. In the first wave of infection, SARS‐CoV‐2 enters host cells through ACE2 and releases its viral RNAs, which are subsequently sensed by TLR3 and RIG‐I/MDA‐5. The activation of TLR3 and RIG‐I/MDA‐5 leads to the activation of innate immune signaling pathways, resulting in the production of IFNs and other inflammatory cytokines. Then, ACE2 was upregulated by these cytokines through the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway or other pathways, which subsequently mediated the enhanced entry of SARS‐CoV‐2 into host cells. ACE2, angiotensin‐converting enzyme 2; IFN, interferon; SARS‐CoV‐2, severe acute respiratory syndrome coronavirus 2; TLR3, Toll‐like receptor 3