Impaired local intrinsic immunity to SARS-CoV-2 infection in severe COVID-19

SARS-CoV-2 infection can cause severe respiratory COVID-19. However, many individuals present with isolated upper respiratory symptoms, suggesting potential to constrain viral pathology to the nasopharynx. Which cells SARS-CoV-2 primarily targets and how infection influences the respiratory epithelium remains incompletely understood. We performed scRNA-seq on nasopharyngeal swabs from 58 healthy and COVID-19 participants. During COVID-19, we observe expansion of secretory, loss of ciliated, and epithelial cell repopulation via deuterosomal cell expansion. In mild and moderate COVID-19, epithelial cells express anti-viral/interferon-responsive genes, while cells in severe COVID-19 have muted anti-viral responses despite equivalent viral loads. SARS-CoV-2 RNA(+) host-target cells are highly heterogenous, including developing ciliated, interferon-responsive ciliated, AZGP1(high) goblet, and KRT13(+) hillock''-like cells, and we identify genes associated with susceptibility, resistance, or infection response. Our study defines protective and detrimental responses to SARS-CoV-2, the direct viral targets of infection, and suggests that failed nasal epithelial anti-viral immunity may underlie and precede severe COVID-19.

Automated summary

Our study reveals the diverse responses of cells in the nasopharyngeal epithelium to SARS-CoV-2 infection, with different gene expression profiles observed in mild, moderate, and severe cases of COVID-19. The identification of specific cell types and associated genes highlights the complexity of the host response to viral infection, and suggests that impaired nasal epithelial anti-viral immunity may contribute to the development of severe COVID-19.