Effects of smoking on the Immune System can last for years, says study

Smoking tobacco is so harmful to the body that it alters the Immune system of a person, leaving them vulnerable to the development of diseases and infections , even years after having stopped smoking. This is what a new study points out.

Although smoking rates have declined since the 1960s, smoking continues to be the leading cause of preventable death in the United States, causing more than 480,000 deaths per year.

For decades, health professionals have warned smokers about how this habit can lead to serious problems , such as lung cancer, heart attacks or stroke. But a study published this Wednesday (14) in the journal Nature offers another reason why stop smoking .

Research shows how smoking decreases the body's ability to fight infections immediately and over time, and puts people at risk for chronic diseases involving inflammation, such as rheumatoid arthritis and lupus.

“Stop smoking as soon as possible,” warned study co-author Violaine Saint-André, an expert in computational biology at the Pasteur Institute in Paris.

“The main message from our study, especially for young people, is that there appears to be a significant impact on long-term immunity, something to never start smoking.”

The researchers looked at blood samples from a group of 1,000 healthy people between the ages of 20 and 69 over time. The group was divided equally between men and women.

The researchers wanted to see how 136 variables, including lifestyle, socioeconomic issues and eating habits, as well as age, sex and genetics, affected the immune response. They exposed blood samples to common germs, such as E. coli bacteria and the flu virus, and measured the immune response.

Body mass index and a latent infection caused by the herpes virus had the biggest impact, with smoking causing the biggest change, having almost the same impact on the immune response as important factors such as age or sex. “It’s considerable,” said Saint-André.

When smokers in the study quit, their immune response improved one level but did not fully recover for years, according to study co-author Darragh Duffy, who directs the Translational Immunology unit at the Pasteur Institute.

“The good news is it’s starting to be restored,” he said. “There is never a good time to start smoking, but if you are a smoker, the best time to quit is now.”

The study also found that the more someone smoked, the more their immune response changed.

“Reducing any amount is still a good thing in terms of this impact,” Duffy said.

The study found that smoking appeared to have long-term epigenetic effects on the immune system's two main forms of protection: the innate response and the adaptive response. The effect on the innate response quickly disappears when someone stops smoking, but the effect on the adaptive response persists even after stopping smoking.

The innate immune response is the general way in which the skin, mucous membranes, immune system cells, and proteins fight germs. It's a quick movement, but it's a blunt instrument. When the body determines that the innate response is not protective enough, the adaptive Immune System comes into play. It is made up of antibodies in blood and other bodily fluids, B and T lymphocytes, which can “remember” a threat and better attack threats that have been seen before.

“The main finding of our study is that smoking has short-term but also long-term effects on adaptive immunity associated with B cells and regulatory T cells and epigenetic changes,” said Saint-André.

The new research, however, has some limitations. The experiment was carried out with blood samples in the laboratory, but the Immune System can react differently in real life. However, human exposure studies are still relatively limited in size compared to what they have been able to show with a large collection of blood samples, according to Duffy.

Yasmin Thanavala, professor of oncology in the Department of Immunology at Roswell Park Cancer Institute, whose research on the immune response to smoking was mentioned in the new study, said the work was “a wonderful validation” of what her research has discovered over the past few years. .

Thanavala's research exposed rats to tobacco smoke instead of human blood. These mice cleared a bacterial infection less efficiently and with a less robust immune response than mice that were not exposed. The changes in the lungs lessen, she said, but “never go away.”

Yasmin points out a limitation of the new study that she hopes the researchers will resolve in the future: the homogeneity of the participants, who were all French and did not have high body weight.

“We know that many things, in addition to smoking, affect our immune response. Our genetic background affects our immune response. There is also growing evidence that our body weight, obesity, affects the immune response,” said Thanavala.

Albert Rizzo, chief medical officer of the American Medical Association, said doctors have long known that smoking causes inflammation in the lungs, but that doesn't explain all immune system problems.

It also appears to explain why even smokers who have quit smoking can develop diseases such as chronic obstructive pulmonary disease or COPD.

“This study is useful because it tells us what we always thought, but now it begins to explain why,” said Rizzo, who was not involved in the research.