Tobacco use reduces the effectiveness of the immune system against viral and bacterial infections, and these negative effects persist for several years after a person quits smoking, although they decrease over time. This finding is based on a study published today in the journal Nature, which suggests that this reduction in some cases may be comparable to natural factors such as age, gender or genetic predisposition.
“You should never start smoking, but for those who already smoke, the optimal time to quit is now,” Darragh Duffy, a researcher at the Institut Pasteur in Paris and leader of the study, said at a news conference. The effects of tobacco on the immune system increase as the number of cigarettes smoked per day increases and the period of smoking increases. Therefore, “a reduction of any amount is positive in terms of impact,” the researcher concluded.
The study, which analyzed the effects of 136 environmental variables on the immune response of 1,000 healthy people, also points to body mass index (i.e. weight) and latent infection with cytomegalovirus (a type of herpes) as factors influencing normal health. functioning of our defense.
However, its influence is much less than that of tobacco. Smoking is the only habit that affects both innate immunity (the body’s first line of defense, causing a general response to any infection) and adaptive immunity (the specific immune response against each pathogen).
Adaptive immunity is what suffers in the long term, even after a person has quit smoking. Tobacco influences this specific response by altering the function of immune cells and causing modifications to the smoker’s DNA, resulting in an altered immune response.
“This suggests that there may be a persistent ‘smoking memory’ in the immune system,” Africa Gonzalez-Fernandez, professor of immunology at the University of Vigo, said in a statement to the Center for Science Media. Thus, the researcher notes, “smokers may be more likely to develop other diseases such as cancer, autoimmune disorders or allergies, or to react abnormally to infections.”
Because the study was conducted on healthy people, it is impossible to determine which diseases might be affected by these changes and which ones would not, the authors acknowledge. However, it allows for a general overview because the results show that tobacco provokes a stronger inflammatory response: “Smokers may experience more severe symptoms, more complications and longer disease duration,” Duffy said.
Population-based studies have repeatedly shown that smoking increases the risk of cancer, respiratory and cardiovascular diseases. The study, presented today in the journal Nature, lays the foundation for understanding the cellular and molecular processes underlying these well-known epidemiological phenomena.
The study involved stimulating blood samples from 1,000 healthy people with agents such as viruses, bacteria and immunological signals. These simulations activated an immune response, which the scientists analyzed by measuring the concentrations of certain cytokines—proteins that coordinate the immune system when the body encounters a pathogen and that are associated with specific effects such as inflammation.
Additionally, during sample collection in 2013, each participant completed a questionnaire detailing their lifestyle, socioeconomic background, dietary habits, and other such factors. By combining these data with immune and written responses, the authors were able to identify the key factors that most influence the immune system.
Future steps include assessing how the influence of each environmental variable on the immune response could influence protection against specific diseases. To do this, the team is re-recruiting volunteers who took part in the study 10 years ago to obtain new blood samples and assess how each of them fared during the COVID-19 pandemic and other illnesses during that period.
In this way, the researchers hope to confirm their findings in the real world and observe the specific effects of smoking on disease development. For now, the discovery provides “the scientific basis for continuing to promote healthy, tobacco-free lifestyles,” conclude Yang Luo and Simon Stent, researchers at the University of Oxford, in an analysis of the study also published in the journal Nature.