New York: While several studies have highlighted the risks that smoking can have on lung health, a new study has identified tobacco smoking as a potential risk factor for infection of the COVID-19 virus.
The current findings, published in the journal American Journal of Respiratory and Critical Care Medicine, suggest that there is an increased risk for the virus binding and gaining entry into the lungs of smokers than non-smokers.
"We hypothesised that the worse outcomes of COVID-19 infections in regions of the world with high levels of cigarette smoking may reflect host factors," said study lead researcher Christopher I Amos from Baylor College of Medicine in the US
For the findings, the research team analysed datasets of the molecule ribonucleic acid (RNA) expressed by various types of lung tissue, comparing the current and former smokers and non-smokers.
They looked at the expression of ACE2, the molecule in the respiratory tract that the COVID-19 virus uses to attach to and infect human cells.
They also looked at the expression of FURIN and TMPRSS2, human enzymes are known to facilitate COVID-19 virus infection.
The researchers reported a 25 per cent increase in the expression of ACE2 in lung tissues from ever-smokers, people who have smoked at least 100 cigarettes during their lives when compared with nonsmokers.
Tobacco smoking also increased the presence of FURIN, but to a lower extent compared to ACE2. TMRPSS2 expression in lungs was not associated with smoking.
They also found that smoking remodelled the gene expression of cells in the lungs so that the ACE2 gene was more highly expressed in goblet cells, cells that secrete mucus in order to protect the mucous membranes in the lungs.
The significant smoking effect on ACE2 pulmonary expression identified in this study indicates not only an increase in the entry points for the COVID-19 virus but also may suggest an increased risk for viral binding and entry of the virus in the lungs of smokers.
The findings provide valuable information for identifying potentially susceptible populations, according to the researchers.
"Studies of COVID-19 patients would help resolve the influence of smoking on COVID-19 outcomes," Amos added.
Earlier this month, a study, published in the European Respiratory Journal, found that people with chronic obstructive pulmonary disease (COPD) and people who currently smoke have a higher level of an enzyme that is the ''entry point for new coronavirus in lungs.