Cigarette Smoke Exposure and Inflammatory Signaling Increase the Expression of the SARS-CoV-2 Receptor ACE2 in the Respiratory Tract.

The factors mediating fatal SARS-CoV-2 infections are poorly understood. Here, we show that cigarette smoke causes a dose-dependent upregulation of Angiotensin Converting Enzyme 2 (ACE2), the SARS-CoV-2 receptor, in rodent and human lungs. Using single-cell sequencing data, we demonstrate that ACE2 is expressed in a subset of secretory cells in the respiratory tract. Chronic smoke exposure triggers the expansion of this cell population and a concomitant increase in ACE2 expression. In contrast, quitting smoking decreases the abundance of these secretory cells and reduces ACE2 levels. Finally, we demonstrate that ACE2 expression is responsive to inflammatory signaling and can be upregulated by viral infections or interferon treatment. Taken together, these results may partially explain why smokers are particularly susceptible to severe SARS-CoV-2 infections. Furthermore, our work identifies ACE2 as an interferon-stimulated gene in lung cells, suggesting that SARS-CoV-2 infections could create positive-feedback loops that increase ACE2 levels and facilitate viral dissemination.

https://www.biorxiv.org/content/biorxiv/early/2020/04/26/2020.03.28.013672.full.pdf

Cigarette smoke exposure and inflammatory signaling increase the expression of the SARS-CoV-2 receptor ACE2 in the respiratory tract

The coronavirus SARS-CoV-2 has infected more than 600,000 people and has overwhelmed hospital systems around the world. However, the factors mediating fatal SARS-CoV-2 infections are poorly understood. Here, we show that cigarette smoke causes a dose-dependent upregulation of Angiotensin Converting Enzyme 2 (ACE2), the SARS-CoV-2 receptor, in rodent and human lungs. Using single-cell sequencing data, we demonstrate that ACE2 is expressed in a subset of epithelial cells that line the respiratory tract, including goblet cells, club cells, and alveolar type 2 cells. Chronic smoke exposure triggers a protective expansion of mucus-secreting goblet cells and a concomitant increase in ACE2 expression. In contrast, quitting smoking causes a decrease in lung ACE2 levels. Taken together, these results may partially explain why smokers are particularly likely to develop severe SARS-CoV-2 infections, and they suggest that quitting smoking could lessen coronavirus susceptibility.

https://www.biorxiv.org/content/biorxiv/early/2020/03/31/2020.03.28.013672.full.pdf

Cigarette smoke triggers the expansion of a subpopulation of respiratory epithelial cells that express the SARS-CoV-2 receptor ACE2

https://hal.univ-reims.fr/hal-02431914/document

Airway epithelial cell differentiation relies on deficient Hedgehog signalling in COPD.

In vitro cultures of primary human airway epithelial cells (hAECs) grown at air–liquid interface have become a valuable tool to study airway biology under normal and pathologic conditions, and for drug discovery in lung diseases such as cystic fibrosis (CF). An increasing number of different differentiation media, are now available, making comparison of data between studies difficult. Here, we investigated the impact of two common differentiation media on phenotypic, transcriptomic, and physiological features of CF and non-CF epithelia. Cellular architecture and density were strongly impacted by the choice of medium. RNA-sequencing revealed a shift in airway cell lineage; one medium promoting differentiation into club and goblet cells whilst the other enriched the growth of ionocytes and multiciliated cells. Pathway analysis identified differential expression of genes involved in ion and fluid transport. Physiological assays (intracellular/extracellular pH, Ussing chamber) specifically showed that ATP12A and CFTR function were altered, impacting pH and transepithelial ion transport in CF hAECs. Importantly, the two media differentially affected functional responses to CFTR modulators. We argue that the effect of growth conditions should be appropriately determined depending on the scientific question and that our study can act as a guide for choosing the optimal growth medium for specific applications.

/pdf/choice-of-differentiation-media-significantly-impacts-cell-dg1hf4cs53.pdf

Choice of Differentiation Media Significantly Impacts Cell Lineage and Response to CFTR Modulators in Fully Differentiated Primary Cultures of Cystic Fibrosis Human Airway Epithelial Cells.

Air-liquid interface culture enables airway epithelial cells to differentiate into a pseudostratified cell layer, consisting of ciliated cells, goblet/secretory cells, and basal cells (Ghio et al., Part Fibre Toxicol 10:25, 2013). This technique is critically important for in vitro studies of lung diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis, since differentiated airway epithelial cells are more representative of the in vivo lung environment than non-differentiated cells (Derichs et al., FASEB J 25:2325-2332, 2011; Hackett et al., Am J Respir Cell Mol Biol 45:1090-1100, 2011;Schneider et al., Am J Respir Crit Care Med 182: 332-340, 2010). Here we describe the process of isolating and expanding human and mouse airway epithelial cells, as well as differentiation of airway epithelial cells by air-liquid interface culture.

Niccolette Schaefer

Papers

Air–Liquid Interface Culture of Human and Mouse Airway Epithelial Cells