What could be sillier than writing a blog post on “smoking and the immune system”? Isn’t it obvious that smoking is bad for your immune system? Current headlines, however, suggest it might not be silly after all.
A Strange News Report
Last week, France24 reported that researchers at a top Paris hospital are beginning a study of Coronavirus infections. The study will determine if nicotine confers some protection from Covid-19. A pattern in their hospital admissions raised the question: only about five percent of their Covid-19 patients are smokers. But in the general French population, 35% are smokers. According to France24, a similar disparity occurred in a study of 1,000 Chinese patients that was published last month.
The French researchers are doing a clinical study. To their credit, they are not encouraging any patients to smoke. Instead, they intend to treat them with nicotine patches. They are testing the hypothesis that nicotine adheres to cell receptors and blocks the virus. This begs the question of whether, in adhering to cell receptors, nicotine blocks neurotransmitters, cytokines, nutrients, or hormones that the cell actually needs.
Smoking and the Immune System
To be clear, this research is not a reason to take up smoking or even nicotine patches. There is still a great deal of testing to be done. And if the researchers had asked me, I would have told them to test a different hypothesis. I would have suggested the hypothesis that smoking so damages the lung cells as to render them less able to nourish the Coronavirus. Covid-19 seems to prefer lung cells. Wouldn’t it target the healthiest ones first?
In fact, researchers have already shown that nicotine suppresses the immune system.
A comprehensive review of cigarette smoking and inflammation published in 2012 described the effects of cigarette smoke. It increases inflammation, skews T-cell activity, impairs response to pathogens, and suppresses anti-tumor functions. Furthermore, smoking leads to chronic inflammation that creates an environment conducive to bacterial infection. It also creates “a state of chronic injury and inflammation of the airways.” At the cellular level, smoking causes abnormal processing of cellular debris, including failure to clear out materials involved in cell death (apoptosis). Further, it induces self-antigens that contribute to autoimmune disorders.
Risks of Smoking
The most revealing research to me, however, appeared in 1983. Researchers published a paper comparing immune factors in the blood of subjects who smoked and a those of a group that had ceased smoking. They found results “consistent with the reversal of changes in immune function associated with smoking.” So, not only does smoking undermine the immune system, but the system begins to recover when you quit smoking.
The damage tobacco smoke does to the respiratory system is so commonplace that we have an everyday expression for it: smoker’s cough. This cough happens, in part, because tobacco smoke causes the immune system to attack the tissue of the lungs, resulting in the inflammation that produces phlegm. Research has shown a strong association between cellular stress signals, immune system activity, and diseases such as chronic obstructive pulmonary disorder (COPD). Smoking appears repeatedly in the presence of heart disease, stroke, several kinds of cancer, rheumatoid arthritis, cataracts, and type 2 diabetes. It also affects fertility in men and tooth and gum health in both sexes.
The bulk of the research says that smoking weakens a healthy immune system. This suggests to me that any protection it confers from Covid-19 is an illusion. Smokers aren’t as susceptible to Covid-19 because their cells are so damaged that the virus tends to skip them in favor of nonsmokers’ healthier tissue. The fifth fundamental of a healthy immune system is don’t smoke. No matter what some French doctors might find in an ill-advised research project.