C5aR inhibition of nonimmune cells suppresses inflammation and maintains epithelial integrity in SARS-CoV-2–infected primary human airway epithelia

Wilfried Posch,Jonathan Vosper,Asma Noureen,Viktoria Zaderer,Christina Witting,Giulia Bertacchi,Ronald Gstir,Przemyslaw A Filipek,Günther K Bonn,Lukas A Huber,Rosa Bellmann-Weiler,Cornelia Lass-Flörl,Doris Wilflingseder

doi:10.1016/j.jaci.2021.03.038

Abstract

BackgroundExcessive inflammation triggered by a hitherto undescribed mechanism is a hallmark of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and is associated with enhanced pathogenicity and mortality.ObjectiveComplement hyperactivation promotes lung injury and was observed in patients suffering from Middle East respiratory syndrome-related coronavirus, SARS-CoV-1, and SARS-CoV-2 infections. Therefore, we investigated the very first interactions of primary human airway epithelial cells on exposure to SARS-CoV-2 in terms of complement component 3 (C3)-mediated effects.MethodsFor this, we used highly differentiated primary human 3-dimensional tissue models infected with SARS-CoV-2 patient isolates. On infection, viral load, viral infectivity, intracellular complement activation, inflammatory mechanisms, and tissue destruction were analyzed by real-time RT-PCR, high content screening, plaque assays, luminex analyses, and transepithelial electrical resistance measurements.ResultsHere, we show that primary normal human bronchial and small airway epithelial cells respond to SARS-CoV-2 infection by an inflated local C3 mobilization. SARS-CoV-2 infection resulted in exaggerated intracellular complement activation and destruction of the epithelial integrity in monolayer cultures of primary human airway cells and highly differentiated, pseudostratified, mucus-producing, ciliated respiratory tissue models. SARS-CoV-2–infected 3-dimensional cultures secreted significantly higher levels of C3a and the proinflammatory cytokines IL-6, monocyte chemoattractant protein 1, IL-1α, and RANTES.ConclusionsCrucially, we illustrate here for the first time that targeting the anaphylotoxin receptors C3a receptor and C5a receptor in nonimmune respiratory cells can prevent intrinsic lung inflammation and tissue damage. This opens up the exciting possibility in the treatment of COVID-19.

Highlights

Excessive inflammation triggered by a hitherto undescribed mechanism is a hallmark of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and is associated with enhanced pathogenicity and mortality
To monitor SARS-CoV-2 infection in primary normal human bronchial epithelial cells, monolayers and fully differentiated pseudostratified epithelia were infected using different clinical isolates derived from patients with SARS-CoV-2.10,11 The clinical specimens were anonymized before use, and the study has been approved by the Ethics Committee of the Medical University of Innsbruck
human airway epithelia (HAE) cells were infected at an multiplicity of infection (MOI) of 0.1, which is consistent with infection by other coronaviruses, such as HCoV-NL63, SARS-CoV, or Middle East respiratory syndrome-related coronavirus and as used in other settings by Zhu et al[18] to determine morphogenesis and CPEs of SARSCoV-2 infection in HAE.[18,19,20]

Summary

Introduction

Excessive inflammation triggered by a hitherto undescribed mechanism is a hallmark of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and is associated with enhanced pathogenicity and mortality. Objective: Complement hyperactivation promotes lung injury and was observed in patients suffering from Middle East respiratory syndrome-related coronavirus, SARS-CoV-1, and SARS-CoV-2 infections. We investigated the very first interactions of primary human airway epithelial cells on exposure to SARS-CoV-2 in terms of complement component 3 (C3)-mediated effects. Methods: For this, we used highly differentiated primary human 3-dimensional tissue models infected with SARS-CoV-2 patient isolates. Results: Here, we show that primary normal human bronchial and small airway epithelial cells respond to SARS-CoV-2 infection by an inflated local C3 mobilization. SARS-CoV-2 infection resulted in exaggerated intracellular complement activation and destruction of the epithelial integrity in

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