Search

The immune system of most SARS-CoV-2 infected individuals limits viral spread to the upper airways without pulmonary involvement. This prevents the development of pneumonic COVID-19. However, the protective immunological responses causative of successful viral containment in the upper airways remain unclear. Here, we combine longitudinal single-cell RNA sequencing, proteomic profiling, multidimensional flow cytometry, RNA-Seq of FACS-sorted leukocyte subsets and multiplex plasma interferon profiling to uncover temporally resolved protective immune signatures in non-pneumonic and ambulatory SARS-CoV-2 infected patients.We compare host responses in a high-risk patient population infected with SARS-CoV-2 but without pulmonary involvement to patients with COVID-19 pneumonia. Our data reveal a distinct immunological signature of successful viral containment, characterized by an early prominent interferon stimulated gene (ISG) upregulation across immune cell subsets. In addition, reduced cytotoxic potential of Natural Killer (NK) and T cells, as well as a monocyte phenotype with immune-modulatory potential are hallmarks of protective immunity. Temporal resolution across disease trajectories highlights ISG upregulation as particularly prominent early in the disease and confirms increased expression also in comparison to healthy controls.We validate this distinct temporal ISG signature by in-depth RNA-seq of FACS-sorted leukocyte subsets in a large prospective ambulatory SARS-CoV-2 infected cohort confirming early and robust ISG upregulation particularly in monocytes and T cells. In vitro experiments show that Stimulator of Interferon Genes (STING) agonist treatment of PBMCs recapitulates the identified protective immunological signature and might therefore offer a novel therapeutic approach in early disease, without being affected by previously described anti-interferon antibodies. In conclusion, our data demonstrate a protective ISG phenotype in patients with successful containment of SARS-CoV-2 infection without progression to COVID-19. This early protective interferon response might be exploited as a therapeutic approach and for disease course prediction. Funding: This study was supported by the Deutsche Herzstiftung e.V., Frankfurt a.M. [LN],Deutsche Forschungsgemeinschaft (DFG) SFB 914 (S.M. [B02 and Z01], K.S. [B02]), the DFG SFB 1123 (S.M. [B06], K.S. [A07]), M.J and R.Z [Z02]), the DFG FOR 2033 (S.M.), the DGF SFB1243 (W.E., L.E.W. [A14], the DGF EN 1093/2-1 (W.E., A.J.), the German Centre for Cardiovascular Research (DZHK) (Clinician Scientist Programme [L.N.], MHA 1.4VD [S.M.]), DZIF MD student programme (TI 07.003_Deak [F.D.]), FP7 program (project 260309, PRESTIGE [S.M.]), FoFoLe project 1015/1009 (L.N.), and the DFG Clinician Scientist Programme PRIME (413635475, K.P., R.K.). The work was also supported by the European Research Council (ERC 2018-ADG “IMMUNOTHROMBOSIS” [S.M.] and ERC- “T-MEMORE” [K.S.])The CORKUM cohort study was supported by LMUexcellent, funded by the Federal Ministry of Education and Research (BMBF) and the Free State of Bavaria under the Excellence Strategy of the Federal Government and the Lander.The Koco19-Immu Study is funded by Bavarian State Ministry of Science and the Arts, University Hospital, LMU Munich, Helmholtz Centre Munich, University of Bonn, University of Bielefeld, German Ministry for Education and Research (Project No.: 01KI20271). Conflict of Interest: The authors declare no conflict of interest. Ethical Approval: In accordance with the Declaration of Helsinki, and with the approval of the Ethics Committee of Ludwig-Maximilian University Munich, informed consent of the patients or their guardians was obtained. COVID-19 patients are part of the COVID-19 Registry of the LMU University Hospital Munich (CORKUM, WHO trial ID DRKS00021225). Pseudonymizeddata was used for analysis, the CORKUM and KocoImmu studies were approved by the ethics committee of LMUMunich (No: 20-245 & No: 20-371 respectively).

Journal of thrombosis and haemostasis : JTH 19(2), 574-581 (2021). doi:10.1111/jth.15179, Published by Wiley-Blackwell, Oxford

Neutrophils provide a critical line of defense in immune responses to various pathogens, inflicting self-damage upon transition to a hyperactivated, procoagulant state. Recent work has highlighted proinflammatory neutrophil phenotypes contributing to lung injury and acute respiratory distress syndrome (ARDS) in patients with coronavirus disease 2019 (COVID-19). Here, we use state-of-the art mass spectrometry-based proteomics and transcriptomic and correlative analyses as well as functional in vitro and in vivo studies to dissect how neutrophils contribute to the progression to severe COVID-19. We identify a reinforcing loop of both systemic and neutrophil intrinsic IL-8 (CXCL8/IL-8) dysregulation, which initiates and perpetuates neutrophil-driven immunopathology. This positive feedback loop of systemic and neutrophil autocrine IL-8 production leads to an activated, prothrombotic neutrophil phenotype characterized by degranulation and neutrophil extracellular trap (NET) formation. In severe COVID-19, neutrophils directly initiate the coagulation and complement cascade, highlighting a link to the immunothrombotic state observed in these patients. Targeting the IL-8-CXCR-1/-2 axis interferes with this vicious cycle and attenuates neutrophil activation, degranulation, NETosis, and IL-8 release. Finally, we show that blocking IL-8-like signaling reduces severe acute respiratory distress syndrome of coronavirus 2 (SARS-CoV-2) spike protein-induced, human ACE2-dependent pulmonary microthrombosis in mice. In summary, our data provide comprehensive insights into the activation mechanisms of neutrophils in COVID-19 and uncover a self-sustaining neutrophil-IL-8 axis as a promising therapeutic target in severe SARS-CoV-2 infection.