Tobacco continues to affect the immune system up to 15 years after quitting cigarettes

Le tabagisme aurait des effets néfastes sur le système immunitaire, longtemps après l'arrêt du tabac, rapporte une étude de l'Institut Pasteur. Solid photos/Shutterstock

Selon une étude de l'Institut Pasteur, publiée ce mercredi 14 février, le tabagisme pourrait avoir une influence sur la réponse immunitaire pendant 10 à 15 ans après avoir arrêté de fumer. 

Cancers, cardiovascular diseases, deficiencies, infertility: cigarettes cause many harmful effects on health, and some are still little known, or even unknown. A new study reveals that smoking could impact the immune system in the long term. These harmful effects could even persist "for ten or fifteen years" after stopping smoking. Explanations.

"I never get sick, I have a very good immune system". Often pronounced mechanically, this banal phrase says a lot about how the immune system acts in the face of certain microbial attacks, varying considerably from one individual to another. While it is known that certain factors influence these immune responses, such as age, sex, and even heredity, others are currently less known. This is the case of smoking, a factor in which a team of researchers from the Pasteur Institute was interested. The latter is therefore based on the Milieu Interior cohort, which is working to determine and evaluate the genetic and environmental factors likely to modify immune responses.

"We know that certain factors, such as age, sex or genes, strongly impact the immune system but with this new study, we wanted to know which other factors had the most influence" ;, explains Darragh Duffy, head of the Translational Immunology unit at the Pasteur Institute, in a press release. For the purposes of their work, the scientists took blood samples from 1,000 healthy participants aged 20 to 70 years old, from the Interior Environment cohort, and subjected them to numerous microbes, to observe the reaction of their immune system. All by measuring the levels of cytokines, proteins involved in immune defenses.

As much influence as age, sex or genetic variables

Published in the journal Nature, this work sought to determine which factors most influenced immune responses, including body mass index, smoking, sleep, physical activity, vaccination. , or even childhood illnesses. This research made it possible to distinguish three variables more influential than the others, including smoking. A factor which, according to Darragh Duffy, "could have as much influence on certain immune responses as age, sex or genetic variables”. Scientists not only observed a greater inflammatory response in smokers, but also an alteration in the activity of cells involved in immune memory.

"By comparing the immune responses of smokers and ex-smokers, we found that the inflammatory response quickly returned to normal after stopping smoking but that the ;rsquo;impact on adaptive immunity lasted over time, for ten or fifteen years,” continues the researcher. And to specify: "This is the first time that we have highlighted the long-term influence of smoking on immune responses". The team of scientists explains this phenomenon by epigenetic mechanisms, in other words by reversible modifications of gene expression linked to immune defenses.

These findings could provide a better understanding of the impact of smoking on immunity in healthy and sick people, and also show the importance of smoking ;stop smoking as soon as possible. A recent Canadian study, which looked at the impact of stopping smoking, not on immunity, but on life expectancy , for its part showed that the benefits occurred quickly and at any age.