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Xu H, Akinyemi IA, Chitre SA, Loeb JC, Lednicky JA, McIntosh MT, Bhaduri-McIntosh S. SARS-CoV-2 viroporin encoded by ORF3a triggers the NLRP3 inflammatory pathway. Virology 2022; 568:13-22. [PMID: 35066302 PMCID: PMC8762580 DOI: 10.1016/j.virol.2022.01.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 02/08/2023]
Abstract
Heightened inflammatory response is a prominent feature of severe COVID-19 disease. We report that the SARS-CoV-2 ORF3a viroporin activates the NLRP3 inflammasome, the most promiscuous of known inflammasomes. Ectopically expressed ORF3a triggers IL-1β expression via NFκB, thus priming the inflammasome. ORF3a also activates the NLRP3 inflammasome but not NLRP1 or NLRC4, resulting in maturation of IL-1β and cleavage/activation of Gasdermin. Notably, ORF3a activates the NLRP3 inflammasome via both ASC-dependent and -independent modes. This inflammasome activation requires efflux of potassium ions and oligomerization between the kinase NEK7 and NLRP3. Importantly, infection of epithelial cells with SARS-CoV-2 similarly activates the NLRP3 inflammasome. With the NLRP3 inhibitor MCC950 and select FDA-approved oral drugs able to block ORF3a-mediated inflammasome activation, as well as key ORF3a amino acid residues needed for virus release and inflammasome activation conserved in the new variants of SARS-CoV-2 isolates across continents, ORF3a and NLRP3 present prime targets for intervention.
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Affiliation(s)
- Huanzhou Xu
- Division of Infectious Disease, Department of Pediatrics, University of Florida, Gainesville, FL, USA
| | - Ibukun A. Akinyemi
- Child Health Research Institute, Department of Pediatrics, University of Florida, Gainesville, FL, USA
| | - Siddhi A. Chitre
- Division of Infectious Disease, Department of Pediatrics, University of Florida, Gainesville, FL, USA
| | - Julia C. Loeb
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, USA,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - John A. Lednicky
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, USA,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Michael T. McIntosh
- Child Health Research Institute, Department of Pediatrics, University of Florida, Gainesville, FL, USA,Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL, USA
| | - Sumita Bhaduri-McIntosh
- Division of Infectious Disease, Department of Pediatrics, University of Florida, Gainesville, FL, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL, USA.
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