The lungs of people who smoke may contain more of the receptors that the new coronavirus uses to invade cells.
Smoking is injurious to health. Everybody knows that. Heart problems, cancer, lung problems, impotence. There are several diseases that can be caused by smoking. Even non-smokers who are around smokers for quite some time are at risk of developing diseases due to second-hand smoking. So people all over the world are advised to quit smoking because of so many health problems.
Now you can add one more reason to the list for quitting smoking. The danger of contracting coronavirus. Yes, you heard it right. People who smoke regularly are more susceptible to be infected by the latest and dangerous COVID-19.
Several studies suggest that people who smoke are significantly more likely than people who do not to develop a severe form of the illness.
For example, according to a recent study of COVID-19 cases in hospitals in mainland China, 11.8% of people who smoked had a non-severe form of the disease, while 16.9% had severe disease.
To break into cells and start replicating itself, the virus latches onto a protein receptor called angiotensin-converting enzyme 2 (ACE2). which is present in the cells’ membranes.
To find out if people who smoke have more of these receptors in their lungs, researchers at Cold Spring Harbor Laboratory in New York, reviewed data from a genetic study that exposed mice to diluted cigarette smoke for 2, 3, or 4 hours per day for a period of 5 months.
They found that the longer the mice had exposure to cigarette smoke, the more ACE2 receptors were expressed in their lungs.
The scientists later investigated whether or not the same “dose-dependent” relationship between smoking and ACE2 applied in humans.
They analyzed two existing genetic datasets: one based on lung tissue samples from people who smoke who are undergoing thoracic surgery, and one based on lung tissue from people in the National Cancer Institute’s Cancer Genome Atlas Program.
The researchers report that lung samples from those who smoked most heavily expressed the highest levels of ACE2. Even after accounting for the participants’ age, sex, ethnicity, and body mass index (BMI), there remained a strong association between smoking and ACE2.
They also discovered that quitting smoking reversed the increase in ACE2 expression. Among those who had not smoked for a year, quitting was associated with a decrease in ACE2 expression of around 40%, compared with those who currently smoke.
Goblet cells
The researchers managed to trace the additional ACE2 receptors in people who smoke to goblet cells. These are lung cells that secrete mucus. Smoking increases the number of goblet cells, which helps protect the airways from the irritants in smoke.
An unfortunate consequence of this may be to make people who smoke more vulnerable to severe SARS-CoV-2 infections. Having more goblet cells means that they have more of the ACE2 receptors that the virus uses to invade cells.
All in all, it would be good to say goodbye to your smoking habit among this dangerously increasing pandemic of COVID-19
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