CD169-mediated restrictive SARS-CoV-2 infection of macrophages induces pro-inflammatory responses

S Jalloh, J Olejnik, J Berrigan, A Nisa, EL Suder… - PLoS …, 2022 - journals.plos.org
S Jalloh, J Olejnik, J Berrigan, A Nisa, EL Suder, H Akiyama, M Lei, S Ramaswamy, S Tyagi
PLoS pathogens, 2022journals.plos.org
Exacerbated and persistent innate immune response marked by pro-inflammatory cytokine
expression is thought to be a major driver of chronic COVID-19 pathology. Although
macrophages are not the primary target cells of SARS-CoV-2 infection in humans, viral RNA
and antigens in activated monocytes and macrophages have been detected in post-mortem
samples, and dysfunctional monocytes and macrophages have been hypothesized to
contribute to a protracted hyper-inflammatory state in COVID-19 patients. In this study, we …
Exacerbated and persistent innate immune response marked by pro-inflammatory cytokine expression is thought to be a major driver of chronic COVID-19 pathology. Although macrophages are not the primary target cells of SARS-CoV-2 infection in humans, viral RNA and antigens in activated monocytes and macrophages have been detected in post-mortem samples, and dysfunctional monocytes and macrophages have been hypothesized to contribute to a protracted hyper-inflammatory state in COVID-19 patients. In this study, we demonstrate that CD169, a myeloid cell specific I-type lectin, facilitated ACE2-independent SARS-CoV-2 fusion and entry in macrophages. CD169-mediated SARS-CoV-2 entry in macrophages resulted in expression of viral genomic and subgenomic RNAs with minimal viral protein expression and no infectious viral particle release, suggesting a post-entry restriction of the SARS-CoV-2 replication cycle. Intriguingly this post-entry replication block was alleviated by exogenous ACE2 expression in macrophages. Restricted expression of viral genomic and subgenomic RNA in CD169+ macrophages elicited a pro-inflammatory cytokine expression (TNFα, IL-6 and IL-1β) in a RIG-I, MDA-5 and MAVS-dependent manner, which was suppressed by remdesivir treatment. These findings suggest that de novo expression of SARS-CoV-2 RNA in macrophages contributes to the pro-inflammatory cytokine signature and that blocking CD169-mediated ACE2 independent infection and subsequent activation of macrophages by viral RNA might alleviate COVID-19-associated hyperinflammatory response.
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