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editorial
. 2024 Sep 12;64(3):2302302. doi: 10.1183/13993003.02302-2023

FIGURE 2.

FIGURE 2

A proposed small airway landscape in the pulmonary long COVID mucosa (left) compared to a healthy mucosa (right). Secretory cell expression of interleukin (IL)-8 and other cytokines leads to infiltration of neutrophils into the airway lumen from the vasculature. Upregulation of IL-33 by club cells further promotes a pro-inflammatory cascade consisting of activation and recruitment of neutrophils, infiltration of monocytes and their differentiation into tissue macrophages, among other changes. Enrichment in the neutrophil-associated activation signature results in the increase of mucin gene expression in the secretory cells, and consequently excess mucus production by these cells.