Type 2 inflammation reduces SARS-CoV-2 replication in the airway epithelium in allergic asthma through functional alteration of ciliated epithelial cells.J Allergy Clin Immunol. 2023 Jul; 152(1):56-67.JA
Despite well-known susceptibilities to other respiratory viral infections, individuals with allergic asthma have shown reduced susceptibility to severe coronavirus disease 2019 (COVID-19).
We sought to identify mechanisms whereby type 2 inflammation in the airway protects against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by using bronchial airway epithelial cells (AECs) from aeroallergen-sensitized children with asthma and healthy nonsensitized children.
We measured SARS-CoV-2 replication and ACE2 protein and performed bulk and single-cell RNA sequencing of ex vivo infected AEC samples with SARS-CoV-2 infection and with or without IL-13 treatment.
We observed that viral replication was lower in AECs from children with allergic asthma than those from in healthy nonsensitized children and that IL-13 treatment reduced viral replication only in children with allergic asthma and not in healthy children. Lower viral transcript levels were associated with a downregulation of functional pathways of the ciliated epithelium related to differentiation as well as cilia and axoneme production and function, rather than lower ACE2 expression or increases in goblet cells or mucus secretion pathways. Moreover, single-cell RNA sequencing identified specific subsets of relatively undifferentiated ciliated epithelium (which are common in allergic asthma and highly responsive to IL-13) that directly accounted for impaired viral replication.
Our results identify a novel mechanism of innate protection against SARS-CoV-2 in allergic asthma that provides important molecular and clinical insights during the ongoing COVID-19 pandemic.