Transcriptomic Profiling of Neutrophils and Low-Density Granulocytes in COVID-19 Patients

The severity of COVID-19 is linked to excessive inflammation. Neutrophils represent a critical arm of the innate immune response and are major mediators of inflammation, but their role in COVID-19 pathophysiology remains poorly understood. We conducted transcriptomic profiling of neutrophils obtained from patients with mild and severe COVID-19, as well as from non-infected healthy controls. Additionally, low-density granulocytes (LDGs) from patients with severe COVID-19 were included to understand their unique role. Transcriptomic analysis of polymorphonuclear cells (PMNs), consisting mainly of mature neutrophils, revealed a striking type I interferon (IFN-I) gene signature in severe COVID-19 patients, contrasting with mild COVID-19 and healthy controls. LDGs from severe COVID-19 patients exhibited an immature neutrophil phenotype and lacked this IFN-I signature. These findings underscore the crucial role of neutrophil inflammasomes in driving inflammation during severe COVID-19. The study provides insights into the pathological mechanisms of severe COVID-19 and highlights potential targets for therapeutic intervention.