Immunomodulation of Human Alveolar Macrophage Response to the SARS-CoV-2 S Protein by Oral Microbiota

Abstract

Background: The oral microbiota is formed by microorganisms that are normal inhabitants of the oral cavity. Recent studies have shown that these organisms are highly dynamic and not strictly confined to the oral cavity, being found in the lung alveoli where they take residence. The severity of coronavirus disease 2019 (COVID-19), caused by the inflammatory response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can be affected by alterations in the oral microbiota. We aimed to study the relationship between the oral microbiota and the inflammatory response to SARS-CoV-2 S protein by human alveolar macrophages.

Methods: Human alveolar macrophages (Daisy cells) transfected with a nuclear factor kappa B (NF-кB) reporter plasmid were first exposed to bacteria belonging to the oral microbiota: Corynebacterium spp., Prevotella oralis, Streptococcus viridans, Veillonella spp., and Fusobacteriu spp., and then stimulated to the SARS-CoV-2 S protein trimer.

Results: We observed an overall decrease in the activation of inflammatory transcription factor NF-кB when alveolar macrophages were exposed to oral commensals.

Conclusions: These findings demonstrate an immunomodulatory role of the oral microbiota in the response to SARS-CoV-2 by alveolar macrophages, and may offer alternative therapeutic options for treating or preventing severity in COVID-19.

Clin Infect Immun. 2024;9(1):16-19
doi: https://doi.org/10.14740/cii167