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RESTRICTED INFECTION of MACROPHAGES by SARS-CoV-2 INDUCES PROINFLAMMATORY RESPONSES
Topics in Antiviral Medicine ; 30(1 SUPPL):64, 2022.
Article in English | EMBASE | ID: covidwho-1880376
ABSTRACT

Background:

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been associated with immune hyperactivation and high levels of proinflammatory cytokines. Extensive lung infiltration by CD169+ inflammatory monocytes and presence of activated CD169+ alveolar macrophages suggest monocyte/macrophages are key drivers of severe morbidity and mortality. In this study, we determined whether CD169 mediated ACE2-independent SARS-CoV-2 entry and restricted viral genome replication in macrophages triggers pro-inflammatory cytokine expression.

Methods:

Monocyte-derived macrophages (MDMs) and PMA-differentiated THP-1 macrophages engineered to constitutively express CD169, ACE2, or CD169 and ACE2 were infected with USA-WA1/2020/SARS-CoV-2 isolate with or without Remdesivir pre-treatment. To identify mechanism of innate immune activation, nucleic acid sensing pathways were selectively depleted in CD169+ macrophages. Extent of viral genomic (gRNA) and sub-genomic (sgRNA) expression and induction of pro-inflammatory cytokines was determined by qRT-PCR and single molecule RNA FISH analysis. Viral protein expression and infectious virus particle production was determined by immunofluorescence analysis and TCID50.

Results:

While productive virus infection (viral protein expression and infectious virus particle release) was only observed in ACE2+ macrophages, SARS-CoV-2 N or S expression and infectious virus production was not observed in CD169+ macrophages. Co-expression of ACE2 and CD169 significantly enhanced infectious virus production and spread. Interestingly, smFISH and RT-qPCR analysis revealed CD169+ cells express cytosolic negative-strand gRNA and positive strand sgRNA. Importantly, CD169-mediated SARS-CoV-2 infection of macrophages and expression of viral mRNAs led to induction of pro-inflammatory cytokines, IL-6, TNFα, and IL-1β, despite lack of viral protein expression in CD169+ macrophages. Pre-treatment with Remdesivir blocked de novo expression of viral mRNAs and induction of inflammatory cytokines in CD169-dependent infection of macrophages. Furthermore, knockdown of cytosolic RLRs (RIG-I and MDA-5) or MAVS significantly attenuated inflammatory cytokine expression in CD169+ macrophages, confirming that nucleic acid sensing of restricted cytosolic viral mRNA expression in macrophages triggers innate immune activation.

Conclusion:

These results suggest that restricted SARS-CoV-2 infection of CD169+ macrophages contributes to COVID-19-associated hyperinflammatory cytokine response.
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Collection: Databases of international organizations Database: EMBASE Language: English Journal: Topics in Antiviral Medicine Year: 2022 Document Type: Article

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Collection: Databases of international organizations Database: EMBASE Language: English Journal: Topics in Antiviral Medicine Year: 2022 Document Type: Article