A model of airway tissue created from human stem cells potentially shows why COVID-19 infections are more severe in smokers.
University of California Los Angeles (UCLA) researchers used an air-liquid interface culture, a culture grown from human airway stem cells and closely replicating how the airways behave and function.
The cultures were grown from airway stem cells taken from live, nonsmoking tissue donors. The cultures then were exposed to cigarette smoke for three minutes daily for four days.
The cultures and a control group were exposed to SARS-CoV-2, the virus that causes COVID-19. When compared, the cultures exposed to smoke contained between two and three times more infected cells.
“Our model replicates the upper part of the airways, which is the first place the virus hits,” said Dr. Brigitte Gomperts, professor of pulmonary medicine and member of the UCLA Jonsson Comprehensive Cancer Center. “This is the part that produces mucus to trap viruses, bacteria, and toxins and contains cells with finger-like projections that beat that mucus up and out of the body.”
Smoking blocks the immune system’s messenger proteins interferons that are part of the body’s early immune response. Interferons produce proteins to attack a virus and alert uninfected cells to prepare to fight the virus.