The following is a summary of “Type 2 inflammation reduces SARS-CoV-2 replication in the airway epithelium in allergic asthma through functional alteration of ciliated epithelial cells,” published in the JULY 2023 issue of Allergy & Immunology by Jayavelu, et al.
Individuals with allergic asthma have shown reduced susceptibility to severe coronavirus disease 2019 (COVID-19), despite being susceptible to other respiratory viral infections. The protective mechanisms of type 2 inflammation in the airway against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in these individuals have yet to be well understood. For a study, researchers sought to investigate how type 2 inflammation in the airway protects against severe COVID-19 by using bronchial airway epithelial cells (AECs) from children with allergic asthma and healthy nonsensitized children.
The researchers measured SARS-CoV-2 replication and ACE2 protein levels in ex vivo infected AEC samples from children with allergic asthma and healthy children. They also performed bulk and single-cell RNA sequencing of the infected AEC samples with and without IL-13 treatment.
The study found that viral replication was lower in AECs from children with allergic asthma than healthy nonsensitized children. Additionally, IL-13 treatment reduced viral replication only in children with allergic asthma, not healthy children. The lower viral transcript levels were associated with the downregulation of functional pathways in the ciliated epithelium related to differentiation, cilia, and axoneme production and function. The effect was independent of ACE2 expression levels or changes in goblet cells or mucus secretion pathways. They identified subsets of relatively undifferentiated ciliated epithelium, common in allergic asthma and highly responsive to IL-13, as directly responsible for impaired viral replication.
The findings revealed a novel innate protection mechanism against SARS-CoV-2 in allergic asthma. The study shed light on important molecular and clinical insights that can contribute to the understanding of COVID-19 and its impact on individuals with allergic asthma during the ongoing pandemic.