Smoking worsens SARS-CoV-2 infection in the airways

Microscopic images of human stem cell-derived airway tissue models with cell nuclei (blue) and SARS-CoV-2-infected cells (green); tissue exposed to cigarette smoke (right) had 2 to 3 times more infected cells than non-exposed tissue (left). Credit: UCLA Broad Stem Cell Research Center/Cell Stem Cell Microscopic images of human stem cell-derived airway tissue models with cell nuclei (blue) and SARS-CoV-2-infected cells (green); tissue exposed to cigarette smoke (right) had 2 to 3 times more infected cells than non-exposed tissue (left). UCLA researchers using a model of airway tissue created from human stem cells have pinpointed how smoking cigarettes causes more severe infection by SARS-CoV-2, the virus that causes COVID-19, in the airways of the lungs. The research, led by scientists at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA and published in the journal Cell Stem Cell , will help scientists better understand COVID-19 risks for smokers and could inform the development of new therapeutic strategies to help reduce smokers' chances of developing severe disease. Cigarette smoking is one of the most common causes of lung diseases, including lung cancer and chronic obstructive pulmonary disease, and most demographic studies of COVID-19 patients have indicated that current smokers are at increased risk of severe infection and death. But the reasons why have not been entirely clear.