Cigarette smoke worsens COVID-19 infection in lungs — these images prove it
Smoking cigarettes is known to increase risks of severe COVID-19 and death, and now new microscopic photos that zoom into a human airway tissue model reveals why that’s the case.
Five young, healthy, non-smokers donated airway stem cells from their lungs to researchers at the University of California, Los Angeles, to create a laboratory model that replicates how human airways behave when infected with SARS-CoV-2, the virus that causes COVID-19.
The team realized that airways exposed to cigarette smoke produced two to three times more coronavirus-infected cells than airways free of smoke contamination.
The researchers say their findings could help other experts better understand the risks coronavirus-positive smokers face and could aid the development of new therapies to reduce smokers’ chances of developing severe COVID-19 or dying from it.
A study was published Tuesday in the journal Cell Stem Cell.
“If you think of the airways like the high walls that protect a castle, smoking cigarettes is like creating holes in these walls,” study co-senior author Dr. Brigitte Gomperts, a pulmonary medicine professor and member of the UCLA Broad Stem Cell Research Center, said in a news release. “Smoking reduces the natural defenses and that allows the virus to set in.”
The airways are the body’s “first line of defense against airborne pathogens like viruses, bacteria and smoke,” the UCLA researchers said. They produce mucus to trap foreign materials and remove them as quickly as possible.
So, with the donated stem cells, the team created a model known as an “air-liquid interface culture” and exposed the airways to cigarette smoke for three minutes per day over four days.
They then infected the cultures, and others not exposed to cigarette smoke, with live coronavirus and compared how they behaved. Like past evidence shows, smokers’ cells produced more virus than non-smokers’ cells.
Microscopic images of the models show cell nuclei (pictured in blue) alongside coronavirus infected cells (pictured in green). As shown above, the picture on the right is of tissue exposed to cigarette smoke; the picture on the left shows non-exposed tissue.
The team also found that smoke blocked a portion of immune system activity. The smoke reduces the natural responses of interferons, proteins that tell infected cells to attack the virus and alert healthy cells to prepare for battle.
A study published in July found that one in three young adults aged 18 to 25 are “medically vulnerable to severe COVID-19” largely because of their smoking habits rather than underlying health conditions, McClatchy News reported.
Vapers face similar risks.
A paper released in August discovered that teenagers and young adults between 13 and 24 years old who vape nicotine have a “substantially increased” risk of becoming infected with the coronavirus and coming down with unpleasant symptoms.
Specifically, young vapers were five to seven times more likely to be infected with COVID-19 than those who did not vape.
This story was originally published November 18, 2020 at 1:15 PM with the headline "Cigarette smoke worsens COVID-19 infection in lungs — these images prove it."
