Smoking alters the immune system even years after quitting

 Smoking not only increases the predisposition to develop diseases. Tobacco alters the immune system even years after quitting. Following the path opened in the 90s by researcher Polly Matzinger, who described the internal control and protection work of the human body carried out by the immune system, a study published this Wednesday in the magazine, ‘Nature‘ has tried to answer the question of What external environmental factors alter our defenses?.

To obtain an answer, an international team of researchers affiliated with institutions in France, Sweden, and the United States has analyzed the impact of 136 environmental factors on the immune system of 1,000 volunteer people between 20 and 70 years old, in good health, and born over five different decades. Blood samples exposed to these 136 pathogens were analyzed from 200 people per decade, half of whom were women and half men.

The scientists looked specifically at the amount of cytokines (a group of proteins crucial for controlling the activity of immune system cells) the people studied secreted to defend themselves against these pathogens and coordinate the immune response to combat them. The conclusion was clear: Smoking had the most influence on the immune response of all the environmental factors examined.

One of the authors, Violaine Saint-André, a researcher at the Pasteur Institute in Paris, explained in a press conference organized by ‘Nature’ that smoking alters the body’s defenses in two ways. It affects the “innate or natural” immunity, the body’s congenital ability to destroy any potentially harmful microorganism. Also, it modifies the so-called “adaptive” immunity (mediated by lymphocytes) that produces specific antibodies against each threat.

The body has a “memory” of having smoked.

The scientists discovered that while the alteration of innate immunity is “transitory” and is lost after quitting smoking, damage to adaptive immunity persists, and the amount of cytokines released in an infection or any other health problem remains modified up to 10 or 15 years after a person has given up tobacco.

They observed that There is a correlation between the years a person has been smoking and the number of cigarettes smoked with the persistence of damage to adaptive immunity. After already known factors such as age, sex, genetics, body mass index, or cytomegalovirus infection (a type of herpes), “we now show that smoking is another great modifier of the immune system,” added Saint-André.

“If a person stops smoking, they recover well the part of the innate immunity, not the adaptive immunity. This indicates that the immune system has a memory of having smoked persistently, which has an important implication for smokers,” says África González-Fernández, professor of Immunology at the Spanish University of Vigo, in a reaction collected by the Science Media Center (SMC) platform.

This study “helps explain possible alterations in the immune response that we frequently see in smokers who reach the age of 60 with suspicion of secondary immunodeficiency in the context of chronic obstructive pulmonary disease (COPD) and where a low concentration is seen. Of antibodies,” said Marcos López Hoyos, president of the Spanish Society of Immunology (SEI), in another reaction from the SMC.

What are the long-term consequences?

The alterations that smoking causes in the defenses can manifest themselves in the long term in an increased risk of contracting autoimmune diseases, allergies, or cancer, another of the authors, Darragh Duffy, also affiliated with Pasteur, noted at the same informative meeting. “Our conclusions imply, in the short term, that A person who smokes will suffer a worsening of any disease that involves inflammation compared to someone who does not smoke or has smoked; the symptoms will be more persistent, and there will be a greater possibility of complications and chronicification of the disease,” he added.

The authors recognized that a limiting aspect of the work is the lack of genetic diversity of the individuals studied. All the studies have been carried out with peripheral blood cells. There is no data on how tobacco exposure affects the respiratory level (such as the mucosa and bronchoalveolar fluid).

In addition to the revelations of the research itself, these results “will help to understand better the factors underlying the risk of contracting infections and other diseases related to the immune system, such as cancer,” the scientists noted. Asked what message they would send to citizens as a result of this investigation, the researchers were clear: “There is never a good time to start smoking, and the time to stop is now.”