According to a new study published in the European Respiratory Journal, smokers and individuals with chronic obstructive pulmonary disease (COPD) have higher levels of angiotensin converting enzyme II (ACE2), which is the entry receptor for the SARS-CoV-2 coronavirus, in their lungs; this may explain the increased risk of severe COVID-19 in these subpopulations and highlight importance of smoking cessation.
Active cigarette smoking and COPD up-regulate ACE2 expression in lower airways, which in part may explain the increased risk of severe COVID-19 in these populations. Image credit: Leung et al, doi: 10.1183/13993003.00688-2020.
“The data emerging from China suggested that patients with COPD were at higher risk of having worse outcomes from COVID-19,” said lead author Dr. Janice Leung, a researcher at the University of British Columbia and St. Paul’s Hospital.
“We hypothesized that this could be because the levels of ACE2 in their airways might be increased compared to people without COPD, which could possibly make it easier for the virus to infect the airway.”
Dr. Leung and colleagues studied samples taken from the lungs of 21 COPD patients and 21 people who did not have COPD.
They tested the samples to gauge the level of ACE2 and compared this with other factors, such whether they were from people who never smoked, were current smokers or former smokers.
Not only did they find higher levels of ACE2 in COPD patients, they also found higher levels in people who were smokers.
The study authors then checked their new findings against two existing study groups, which together contain data on a further 249 people — some non-smokers, some current smokers and some former smokers.
Again, they found levels of ACE2 were higher in current smokers but lower in non-smokers and in those who were former smokers.
“We found that patients with COPD and people who are still smoking have higher levels of ACE2 in their airways, which might put them at an increased risk of developing severe COVID-19 infections,” Dr. Leung said.
“Patients with COPD should be counseled to strictly abide by social distancing and proper hand hygiene to prevent infection.”
“We also found that former smokers had similar levels of ACE2 to people who had never smoked. This suggests that there has never been a better time to quit smoking to protect yourself from COVID-19.”
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Janice M. Leung et al. ACE-2 Expression in the Small Airway Epithelia of Smokers and COPD Patients: Implications for COVID-19. European Respiratory Journal, published online April 8, 2020; doi: 10.1183/13993003.00688-2020
