Neutrophil Extracellular Traps Contribute to COVID-19 Hyperinflammation and Humoral Autoimmunity.

Jiram Torres-Ruiz,Carlos Núñez-Álvarez,Jaquelin Lira-Luna,Guillermo Juárez-Vega,Abdiel Absalón-Aguilar,David Meza-Sánchez,Alfredo Pérez-Fragoso,José Luis Maravillas-Montero,Miroslava Nuñez-Aguirre,Luis Llorente,Thierry Hernández-Gilsoul,Miguel Tapia-Rodríguez,Diana Gómez-Martín,Nancy R Mejía-Domínguez,Daniel Alberto Carrillo-Vázquez,Beatriz Alcalá-Carmona

doi:10.3390/cells10102545

Abstract

The coronavirus disease 2019 (COVID-19) is related to enhanced production of NETs, and autoimmune/autoinflammatory phenomena. We evaluated the proportion of low-density granulocytes (LDG) by flow cytometry, and their capacity to produce NETs was compared with that of conventional neutrophils. NETs and their protein cargo were quantified by confocal microscopy and ELISA. Antinuclear antibodies (ANA), anti-neutrophil cytoplasmic antibodies (ANCA) and the degradation capacity of NETs were addressed in serum. MILLIPLEX assay was used to assess the cytokine levels in macrophages’ supernatant and serum. We found a higher proportion of LDG in severe and critical COVID-19 which correlated with severity and inflammatory markers. Severe/critical COVID-19 patients had higher plasmatic NE, LL-37 and HMGB1-DNA complexes, whilst ISG-15-DNA complexes were lower in severe patients. Sera from severe/critical COVID-19 patients had lower degradation capacity of NETs, which was reverted after adding hrDNase. Anti-NET antibodies were found in COVID-19, which correlated with ANA and ANCA positivity. NET stimuli enhanced the secretion of cytokines in macrophages. This study unveils the role of COVID-19 NETs as inducers of pro-inflammatory and autoimmune responses. The deficient degradation capacity of NETs may contribute to the accumulation of these structures and anti-NET antibodies are related to the presence of autoantibodies.

Highlights

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been related to exuberant harming autoinflammation and autoimmune responses, especially in critical COVID-19 (Coronavirus Disease 2019) patients [1]
We found a moderate negative correlation between low density granulocytes (LDG) and PaFi (PaO2/FiO2) and positive correlations with features of tissue turnover such as creatine phosphokinase (CPK), lactate dehydrogenase (LDH), Troponin I, and lactate as well as with variables related to immunothrombosis such as D-dimer and pro-thrombin time
We found that patients with severe/critical COVID-19 have an enhanced production and deficient degradation of neutrophil extracellular traps (NETs), which carry a differential protein cargo and are mainly produced by Normal density granulocytes (NDG)

Summary

Introduction

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been related to exuberant harming autoinflammation and autoimmune responses, especially in critical COVID-19 (Coronavirus Disease 2019) patients [1]. Autoantibodies recognizing type I IFN [23], DNA, proteinase-3, myeloperoxidase (MPO), phospholipids and prothrombin [24], have been observed in patients with COVID-19 Some of these antigens are present in NETs and are the targets of anti-nuclear antibodies (ANA) and anti-neutrophil cytoplasmic antibodies (ANCA). The aim of the present work is to address the production of NETs by different neutrophil subsets, their protein cargo and their role as inducers of macrophage and autoimmune responses in COVID-19 patients

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