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Direct activation of the alternative complement pathway by SARS-CoV-2 spike proteins is blocked by factor D inhibition.
Yu, Jia; Yuan, Xuan; Chen, Hang; Chaturvedi, Shruti; Braunstein, Evan M; Brodsky, Robert A.
  • Yu J; Division of Hematology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD.
  • Yuan X; Division of Hematology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD.
  • Chen H; Division of Hematology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD.
  • Chaturvedi S; Division of Hematology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD.
  • Braunstein EM; Division of Hematology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD.
  • Brodsky RA; Division of Hematology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD.
Blood ; 136(18): 2080-2089, 2020 10 29.
Article in English | MEDLINE | ID: covidwho-740364
ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly contagious respiratory virus that can lead to venous/arterial thrombosis, stroke, renal failure, myocardial infarction, thrombocytopenia, and other end-organ damage. Animal models demonstrating end-organ protection in C3-deficient mice and evidence of complement activation in humans have led to the hypothesis that SARS-CoV-2 triggers complement-mediated endothelial damage, but the mechanism is unclear. Here, we demonstrate that the SARS-CoV-2 spike protein (subunit 1 and 2), but not the N protein, directly activates the alternative pathway of complement (APC). Complement-dependent killing using the modified Ham test is blocked by either C5 or factor D inhibition. C3 fragments and C5b-9 are deposited on TF1PIGAnull target cells, and complement factor Bb is increased in the supernatant from spike protein-treated cells. C5 inhibition prevents the accumulation of C5b-9 on cells, but not C3c; however, factor D inhibition prevents both C3c and C5b-9 accumulation. Addition of factor H mitigates the complement attack. In conclusion, SARS-CoV-2 spike proteins convert nonactivator surfaces to activator surfaces by preventing the inactivation of the cell-surface APC convertase. APC activation may explain many of the clinical manifestations (microangiopathy, thrombocytopenia, renal injury, and thrombophilia) of COVID-19 that are also observed in other complement-driven diseases such as atypical hemolytic uremic syndrome and catastrophic antiphospholipid antibody syndrome. C5 inhibition prevents accumulation of C5b-9 in vitro but does not prevent upstream complement activation in response to SARS-CoV-2 spike proteins.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Complement Factor D / Complement Pathway, Alternative / Complement Inactivating Agents / Spike Glycoprotein, Coronavirus / Betacoronavirus Type of study: Prognostic study Limits: Humans Language: English Journal: Blood Year: 2020 Document Type: Article Affiliation country: Blood.2020008248

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Complement Factor D / Complement Pathway, Alternative / Complement Inactivating Agents / Spike Glycoprotein, Coronavirus / Betacoronavirus Type of study: Prognostic study Limits: Humans Language: English Journal: Blood Year: 2020 Document Type: Article Affiliation country: Blood.2020008248