SARS-CoV-2 activates the TLR4/MyD88 pathway in human macrophages: A possible correlation with strong pro-inflammatory responses in severe COVID-19
Sabina Sahanic,
Richard Hilbe,
Christina Dünser,
Piotr Tymoszuk,
Judith Löffler-Ragg,
Dietmar Rieder,
Zlatko Trajanoski,
Anne Krogsdam,
Egon Demetz,
Maria Yurchenko,
Christine Fischer,
Michael Schirmer,
Markus Theurl,
Daniela Lener,
Jakob Hirsch,
Johannes Holfeld,
Can Gollmann-Tepeköylü,
Carl P. Zinner,
Alexandar Tzankov,
Shen-Ying Zhang,
Jean-Laurent Casanova,
Wilfried Posch,
Doris Wilflingseder,
Guenter Weiss,
Ivan Tancevski
Affiliations
Sabina Sahanic
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Richard Hilbe
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Christina Dünser
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Piotr Tymoszuk
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Judith Löffler-Ragg
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Dietmar Rieder
Institute of Bioinformatics, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
Zlatko Trajanoski
Institute of Bioinformatics, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
Anne Krogsdam
Institute of Bioinformatics, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
Egon Demetz
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Maria Yurchenko
Centre of Molecular Inflammation Research, Norwegian University of Science and Technology, Trondheim, Norway; The Central Norway Regional Health Authority, St. Olavs Hospital HF, Trondheim, Norway
Christine Fischer
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Michael Schirmer
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Markus Theurl
Department of Internal Medicine III, Medical University of Innsbruck, Innsbruck, Austria
Daniela Lener
Department of Internal Medicine III, Medical University of Innsbruck, Innsbruck, Austria
Jakob Hirsch
Department of Cardiac Surgery, Medical University of Innsbruck, Innsbruck, Austria
Johannes Holfeld
Department of Cardiac Surgery, Medical University of Innsbruck, Innsbruck, Austria
Can Gollmann-Tepeköylü
Department of Cardiac Surgery, Medical University of Innsbruck, Innsbruck, Austria
Carl P. Zinner
Institute of Medical Genetics and Pathology, University Hospital Basel, Basel, Switzerland
Alexandar Tzankov
Institute of Medical Genetics and Pathology, University Hospital Basel, Basel, Switzerland
Shen-Ying Zhang
Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France; University of Paris, Imagine Institute, Paris, France; St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA
Jean-Laurent Casanova
Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Necker Hospital for Sick Children, Paris, France; University of Paris, Imagine Institute, Paris, France; St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY, USA; Howard Hughes Medical Institute, New York, NY, 10065, USA
Wilfried Posch
Division of Hygiene and Medical Microbiology, Medical University of Innsbruck, Austria; Corresponding author. Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Schöpfstraße 41/R311, 6020 Innsbruck, Austria.
Doris Wilflingseder
Division of Hygiene and Medical Microbiology, Medical University of Innsbruck, Austria; Corresponding author. Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Schöpfstraße 41/R311, 6020 Innsbruck, Austria.
Guenter Weiss
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
Ivan Tancevski
Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria; Corresponding author. Department of Internal Medicine II, Medical University of Innsbruck Anichstraße 35, 6020 Innsbruck, Austria.
Background: Toll-like receptors (TLRs) play a pivotal role in the immunologic response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Exaggerated inflammatory response of innate immune cells, however, may drive morbidity and death in Coronavirus disease 19 (COVID-19). Objective: We investigated the engagement of SARS-CoV-2 with TLR4 in order to better understand how to tackle hyperinflammation in COVID-19. Methods: We combined RNA-sequencing data of human lung tissue and of bronchoalveolar lavage fluid cells derived from COVID-19 patients with functional studies in human macrophages using SARS-CoV-2 spike proteins and viable SARS-CoV-2. Pharmacological inhibitors as well as gene editing with CRISPR/Cas9 were used to delineate the signalling pathways involved. Results: We found TLR4 to be the most abundantly upregulated TLR in human lung tissue irrespective of the underlying pathology. Accordingly, bronchoalveolar lavage fluid cells from patients with severe COVID-19 showed an NF-κB-pathway dominated immune response, whereas they were mostly defined by type I interferon signalling in moderate COVID-19. Mechanistically, we found the Spike ectodomain, but not receptor binding domain monomer to induce TLR4-dependent inflammation in human macrophages. By using pharmacological inhibitors as well as CRISPR/Cas9 deleted macrophages, we identify SARS-CoV-2 to engage canonical TLR4-MyD88 signalling. Importantly, we demonstrate that TLR4 blockage prevents exaggerated inflammatory responses in human macrophages infected with different SARS-CoV-2 variants, including immune escape variants B.1.1.7.-E484K and B.1.1.529 (omicron). Conclusion: Our study critically extends the current knowledge on TLR-mediated hyperinflammatory responses to SARS-CoV-2 in human macrophages, paving the way for novel approaches to tackle severe COVID-19. Take-home message: Our study combining human lung transcriptomics with functional studies in human macrophages clearly supports the design and development of TLR4 - directed therapeutics to mitigate hyperinflammation in severe COVID-19.
