Current Understanding of the Innate Control of Toll-like Receptors in Response to SARS-CoV-2 Infection

The global coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection, threatens the entire world. It has affected every aspect of life and increased the burden on both healthcare and socioeconomic systems. Current studies have revealed that excessive inflammatory immune responses are responsible for the severity of COVID-19, which suggests that anti-inflammatory drugs may be promising therapeutic treatments. However, there are currently a limited number of approved therapeutics for COVID-19. Toll-like receptors (TLRs), which recognize microbial components derived from invading pathogens, are involved in both the initiation of innate responses against SARS-CoV-2 infection and the hyperinflammatory phenotype of COVID-19. In this review, we provide current knowledge on the pivotal role of TLRs in immune responses against SARS-CoV-2 infection and demonstrate the potential effectiveness of TLR-targeting drugs on the control of hyperinflammation in patients with COVID-19.