Direct activation of the alternative complement pathway by SARS-CoV-2 spike proteins is blocked by factor D inhibition

dc.contributorJia Yu
dc.contributorXuan Yuan
dc.contributorHang Chen
dc.contributorShruti Chaturvedi
dc.contributorEvan M. Braunstein
dc.contributorRobert A. Brodsky
dc.contributorRobert Brodsky
dc.contributorChristopher Sperati
dc.contributorMichelle Petri
dc.date.accessioned2020-11-05T15:05:57Z
dc.date.available2020-11-05T15:05:57Z
dc.date.updated2020-11-05T15:05:56Z
dc.description.abstractSevere 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.
dc.identifier.citationJia Yu, Xuan Yuan, Hang Chen, et al. (2020-10-29). "Direct activation of the alternative complement pathway by SARS-CoV-2 spike proteins is blocked by factor D inhibition." Blood. 136 (18).
dc.identifier.urihttp://jhir.library.jhu.edu/handle/1774.2/63237
dc.publisherAmerican Society of Hematology
dc.titleDirect activation of the alternative complement pathway by SARS-CoV-2 spike proteins is blocked by factor D inhibition
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