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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 responses immune, like age, sex, even heredity, others are currently less known. This is the case of smoking, a factor in which a team of researchers has been interested from the Institut Pasteur. The latter was based on the Milieu Interior cohort, which is working to determine and evaluate the genetic and environmental factors likely to modify immune responses.
Certain factors have a greater influence on immune responses
“We know that certain factors, such as age, sex or genes, have a strong impact on 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 Institut Pasteur, in a statement. 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. Published in Nature magazine, this work sought to determine which factors most influenced immune responses, including body mass index, smoking, sleep, physical activity, vaccination, and 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.
The impact on adaptive immunity lasted for ten or fifteen years
“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 impact on adaptive immunity persisted over time, for ten or fifteen“, continues the researcher. And to specify: “This is the first time that we have demonstrated 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 the immunity of healthy and sick people, and also show the importance of quitting smoking as early as possible. A recent Canadian studywho was interested in the impact of stopping smoking, not on immunity, but on life expectancy, for his part showed that the benefits occurred quickly and at any age.