Mast Cell Tryptase and Implications for SARS-CoV-2 Pathogenesis

Abstract

Mast cells (MCs) are heterogenous innate leukocytes producing many inflammatory mediators during viral infections that can be protective or damaging to the host, as is seen in the infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogen responsible for the coronavirus disease that was first identified in 2019 (COVID-19). MCs can sense viruses by diverse mechanisms. They express angiotensin-converting enzyme 2 (ACE2), known as the principal entry receptor for SARS-CoV-2, and tryptase that can promote SARS-CoV-2 infection. Tryptase is one of the most abundant serine proteases released by MCs during degranulation and is reported to have both beneficial and detrimental roles in respiratory diseases. Reviewed here are the potential roles of MC-derived tryptase during COVID-19, the implications it has in the pathogenesis of SARS-CoV-2, and the possibility of treating COVID-19 by targeting tryptase.