Since the emergence of COVID-19, SARS-CoV-2 Omicron variants have demonstrated increased human adaptation. Alveolar and recruited macrophages play a critical role in severe lung inflammation following SARS-CoV-2 infection, yet the mechanisms of viral entry into these immune cells remain incompletely understood. Co-IP MS /MS was used to screen for potential SARS-CoV2 receptors in macrophages. Molecular docking, real-time interaction cytometry, and viral infection assays were employed to validate receptor identification. Single-cell RNA sequencing (scRNA-seq) of bronchoalveolar lavage fluid (BALF) from moderate and severe COVID-19 patients and healthy controls was analyzed to correlate receptor expression with disease severity. Transmission Electron Microscopy (TEM) was utilized to visualize viral particles and membrane fusion events. We identified CD98, a subunit of a heteromeric amino acid transporter, as a novel receptor for the SARS-CoV-2 spike protein. scRNA-seq analysis revealed elevated CD98 expression in pro-inflammatory M1-like macrophages, which were enriched in severe COVID-19 cases. Furthermore, TMPRSS11E, which is upregulated in M1 macrophages, facilitated spike protein cleavage and promoted membrane fusion, as confirmed by TEM. A functional interaction between TMPRSS11E and CD98 was also demonstrated. The CD98/TMPRSS11E complex clusters on M1 macrophages, where CD98 serves both as a marker of inflammatory activation and a mediator of viral entry. Reduced spike cleavage efficiency of the Omicron variant correlates with its diminished entry into M1 macrophages. These findings reveal a CD98/TMPRSS11E-mediated entry mechanism that contributes to the tropism of SARS-CoV-2 for pro-inflammatory macrophages and may influence disease pathogenesis.
Wang et al. (Wed,) studied this question.
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