Neuraminidase is a host‐directed approach to regulate neutrophil responses in sepsis and COVID‐19

Neutrophil overstimulation plays a crucial role in tissue damage during severe infections. As pathogen-derived neuraminidase (NEU) stimulate neutrophils, we investigated whether host NEU can be targeted to regulate neutrophil dysregulation observed in severe infections.The effects of NEU inhibitors in lipopolysaccharide (LPS)-stimulated neutrophils from healthy donors or COVID-19 patients were determined by evaluating the shedding of surface sialic acids, cell activation, and reactive oxygen species (ROS) production. Re-analysis of single-cell RNA sequencing of respiratory tract samples from COVID-19 patients was also carried out. The effects of Oseltamivir on sepsis and betacoronavirus-induced acute lung injury were evaluated in murine models.Oseltamivir and Zanamivir constrain host NEU activity, surface sialic acid release, cell activation, and ROS production by LPS-activated human neutrophils. Mechanistically, LPS increased the interaction of NEU1 with the matrix metalloproteinase (MMP)-9. Inhibition of MMP-9 prevents LPS-induced NEU activity and neutrophil response. In vivo, treatment with Oseltamivir fine-tunes neutrophil migration and improves infection control and host survival in peritonitis and pneumonia sepsis. NEU1 is also highly expressed in neutrophils from COVID-19 patients and treatment of whole blood samples from these patients with Oseltamivir or Zanamivir reduces neutrophil overactivation. Oseltamivir treatment of intranasally infected mice with the mouse hepatitis coronavirus 3 (MHV-3) decreased lung neutrophil infiltration, viral load, and tissue damage.These findings suggest that NEU1-MMP-9 interplay induces neutrophil overactivation. In vivo, it was shown that NEU may serve as a host-directed target to dampen neutrophil dysfunction during severe infections.