Sonia Moreno Madrid
Madrid
Updated Thursday, February 15, 2024-10:25
Smoking Does smoking make you less intelligent?
Tobacco is not only one of the factors that most influences the state of the immune system, at a
similar level to age or genes
, but this damage persists in the long term, even when time has passed since the habit was abandoned. .
These are two clear conclusions presented by a study on the impact of a hundred environmental factors on the body's defenses, carried out based on the analysis of about a thousand people. The results achieved by a team of scientists that make up the European
Millieu Interieur consortium,
led by the Pasteur Institute in Paris, have
just been published in
Nature
.
The study has analyzed the impact of
136 environmental factors
on the variability of immune responses in a thousand volunteer individuals. Tobacco is the factor that causes the most alterations in the immune system. According to the researchers, while some changes caused by these factors are transitory, others can remain for years even if you are no longer exposed to them, and that is the case of smoking.
"Smoking has consequences on the immunity of individuals in the short term, but also in the long term. The latter on adaptive immunity are observed in B cells and regulatory T lymphocytes, as well as in epigenetic changes," he explains in a conference. press release about the study by the first signatory of the work,
Violaine Saint-André
, an immunologist at the Pasteur Institute. These cellular alterations
are closely correlated with the years of smoking and the number of cigarettes smoked
, she points out.
BETTER NEVER START
"So apart from there being an obvious interest in quitting smoking as soon as possible, the key message from this study,
especially for young people
, is that in the interest of the long-term impact on the immune system, you should not start smoking." never," he says.
For his part, the main author of the study,
Darragh Duffy
, also from the Pasteur Department of Immunology, has detailed how the research was carried out on 1,000 healthy volunteers (one hundred women and one hundred men for each decade, between 20 and 69 years of age). , in which parameters such as age, sex, smoking habit, body mass index, genetic variations and cytomegalovirus infection, among others, were determined. By extracting blood samples, they determined the reaction of the immune system to various stimuli, measured through responses such as the production of cytokines, proteins released by the body when faced with a pathogen.
OTHER FACTORS INFLUENCE, BUT IN A TRANSIENT WAY
Among the environmental factors studied, it was demonstrated that smoking has the greatest influence on immune responses:
it affected both innate and adaptive immunity
; the first is a general response, while the second is more specialized and specific to a pathogen. While the effects on innate responses (such as increased inflammatory responses) were transient and were lost after smoking cessation, the effects on the adaptive response persist for many years after smoking cessation, altering the levels of cytokines released. after an infection or other immunological challenges.
Body mass index
and
cytomegalovirus
have also been found to
have notable effects on cytokine secretion, but the associated variation in smoking reached levels equivalent to those related to factors that cannot be changed, such as age, sex and the genetic.
Among the
limitations
of the study, recognized by the authors themselves, are the lack of a replication cohort and limited genetic diversity in the individuals studied.
However, and also recognizing these limitations, the experts who have evaluated the study for SMC Spain agree in highlighting the scientific relevance of these findings. In fact,
Marcos López Hoyos
, president of the
Spanish Society of Immunology (SEI)
is convinced that "more work will come out of this study, since there will be more results due to the methodology used." The scientific director of the
Valdecilla Health Research Institute (IDIVAL)
highlights the study that "helps explain possible alterations in the immune response that
We frequently see in the clinic smokers
(and usually overweight) who reach the age of 60 with suspicion of immunodeficiency secondary to smoking
in the context of chronic obstructive pulmonary disease (COPD) and where hypogammaglobulinemia is seen relatively frequently. [low concentration of antibodies]".
For his part,
Óscar de la Calle-Martín
, a doctor specializing in Immunology at the Hospital de Sant Pau in Barcelona and secretary of the SEI, tells SMC how the work confirms that tobacco, in addition to the direct carcinogenic effect, has other effects on the immune system. "This not only has implications with respect to cancers associated with tobacco: lung, larynx, intestinal, etc. Deregulation of the immune system is a fundamental element for the
generation and expansion of neoplasms
."
'MEMORY OF HAVING SMOKED'
This immunologist adds that "it has also been known for a long time that tobacco increases the incidence of
autoimmune and inflammatory diseases
, has perverse effects on the cardiovascular system or fertility, and many other negative effects. This article reveals that a good part of this effect is due to a long-lasting dysfunction of the adaptive immune system, while its effect is limited and reversible in the innate immune system, it is much longer lasting on lymphocytes and there is a close relationship with the years of smoking and the amount of tobacco. This deleterious effect takes a long time to disappear when you stop smoking.
Africa González-Fernández
, professor of Immunology and researcher at the Biomedical Research Center of the University of Vigo (CINBIO), also alludes to this
: "If a person stops smoking, they recover well the part of the innate immunity, but not the adaptive immunity ( mediated by lymphocytes). This would indicate that
there would be a memory in the immune system
of having smoked
persistently, which has an important implication, since smokers can develop other diseases such as cancer, autoimmunity or allergies, or respond in a different way. "abnormal against infections".