Neutrophils initiate the destruction of the olfactory epithelium during SARS-CoV-2 infection in hamsters

The loss of smell related to SARS-CoV-2 infection is one of the most prevalent symptoms of COVID-19. It is now clear that this symptom is related to the massive infection by SARS-CoV-2 of the olfactory epithelium leading to its desquamation. However, the molecular mechanism behind the destabilization of the olfactory epithelium is less clear. Using golden Syrian hamster, we show here that while apoptosis remains at a low level in damaged infected epithelium, the latter is invaded by innate immunity cells. By depleting the neutrophil population or blocking the activity of neutrophil elastase-like proteinases, we reduced the damage induced by the SARS-CoV-2 infection. Surprisingly, the impairment of neutrophil activity led to a decrease of SARS-CoV-2 infection levels in the nasal cavity. Our results indicate a counterproductive role of neutrophils leading to the release of infected cells in the lumen of the nasal cavity and thereby enhanced spreading of the virus.