Neutrophils in COVID-19.

Nico Reusch,Kevin Baßler,Elena De Domenico,Jonas Schulte-Schrepping,Joachim L Schultze,Lorenzo Bonaguro,Anna C Aschenbrenner

doi:10.3389/fimmu.2021.652470

Abstract

Strong evidence has been accumulated since the beginning of the COVID-19 pandemic that neutrophils play an important role in the pathophysiology, particularly in those with severe disease courses. While originally considered to be a rather homogeneous cell type, recent attention to neutrophils has uncovered their fascinating transcriptional and functional diversity as well as their developmental trajectories. These new findings are important to better understand the many facets of neutrophil involvement not only in COVID-19 but also many other acute or chronic inflammatory diseases, both communicable and non-communicable. Here, we highlight the observed immune deviation of neutrophils in COVID-19 and summarize several promising therapeutic attempts to precisely target neutrophils and their reactivity in patients with COVID-19.

Highlights

Coronavirus disease 2019 (COVID-19), the disease elicited by SARS-CoV-2 infection, has been diagnosed in over 111 million patients and led to over 2.4 million deaths during the 2020 pandemic (WHO, covid19.who.int, as of February 24th, 2021)
Recent advances in single-cell omics technologies have opened up new possibilities to study this cell population in humans, especially in pathological contexts, challenging the understanding that neutrophils are a homogeneous population of short-lived cells [6, 7]
As part of the innate immune system, granulocytes are among the first cells recruited to a Abbreviations: COVID-19, Coronavirus disease 2019; GMP, granulocyte-monocyte progenitor cell; Neu, neutrophil; ISG, interferon-stimulated genes; NET, neutrophil associated extracellular trap; ROS, reactive oxygen species; myeloid-derived suppressor cells (MDSC), granulocyticmyeloid derived suppressor cells; lowdensity neutrophils (LDNs), low-density neutrophils; NE, neutrophil elastase

Summary

Introduction

Coronavirus disease 2019 (COVID-19), the disease elicited by SARS-CoV-2 infection, has been diagnosed in over 111 million patients and led to over 2.4 million deaths during the 2020 pandemic (WHO, covid19.who.int, as of February 24th, 2021). Other important inflammatory mediators such as the complement component C5a contribute to the recruitment of neutrophils to sites of infection [28] and to the activation of NET formation when primed by interferons [29]. A growing body of evidence shows a link between neutrophils and activated platelets that guide their migration into inflamed tissue and induce NET formation [30, 31].

Results

Conclusion