E-cigarettes alter body’s organs, UCSD research team says

Electronic cigarettes can alter the inflammatory state of multiple organs in the body, which can influence how they respond to infections, according to a new report by researchers at the UC San Diego School of Medicine in La Jolla.

Daily use of pod-based e-cigarettes alters inflammation in organ systems including the brain, heart, lungs and colon, the researchers said. Effects vary depending on the e-cigarette flavor and can influence how organs respond to infections, such as the SARS-CoV-2 coronavirus that causes COVID-19.

The study was published April 12 in the journal eLife.

“These pod-based e-cigarettes have only become popular in the last five or so years, so we don’t know much about their long-term effects on health,” said senior study author Dr. Laura Crotty Alexander, a UCSD associate professor of medicine and section chief of pulmonary critical care at the Veterans Affairs San Diego Healthcare System.

More than 12 million adults in the United States use e-cigarettes, with the highest rates of use among those ages 18-24. Despite their popularity, research on e-cigarettes — which emit vapor instead of smoke — has been largely limited to studies of short-term use, older devices such as vape pens or box mods, and e-liquids with significantly lower nicotine concentrations than the modern rechargeable pod-based systems.

Crotty Alexander’s team focused on the current most prominent type of e-cigarette and the most popular flavors, mint and mango. To model chronic e-cigarette use, young adult mice were exposed to flavored aerosols three times a day for three months. Researchers then looked for signs of inflammation across the body.

The report’s authors said they saw the most striking effects in the brain, where several inflammatory markers were elevated, including a brain region critical for motivation and reward processing.

The researchers said the findings raise major concerns because inflammation in that region has been linked to anxiety, depression and addictive behaviors.

Many users are adolescents or young adults whose brains are still developing, “so it’s pretty terrifying to learn what may be happening in their brains, considering how this could affect their mental health and behavior down the line,” Crotty Alexander said.

Juul, a leading e-cigarette brand whose products were the primary focus of the study, has argued that its marketing is targeted at adult cigarette smokers who are looking to quit.

In 2019, Juul announced it would discontinue its mango, creme, fruit, cucumber and mint flavors in the United States amid criticism that they attracted young people.

The study also reported that the inflammatory response varied depending on which flavor was used. For example, the hearts of mice that inhaled mint aerosols were much more sensitive to the effects of bacterial pneumonia, compared with those that inhaled mango aerosols, according to the study.

“This was a real surprise to us,” Crotty Alexander said. “This shows us that the flavor chemicals themselves are also causing pathological changes.”

If someone who frequently uses menthol-flavored e-cigarettes is infected with COVID-19, it’s possible the person’s body would respond differently to the infection, she said.

Inflammation increased in the colon, the study said, particularly after a month of e-cigarette exposure, which could increase risk of gastrointestinal disease.

In contrast, the heart showed decreased levels of inflammatory markers, which the authors said could make cardiac tissue more vulnerable to infection.

Researchers also said that while lungs did not show tissue-level signs of inflammation, several changes were observed in the samples, calling for further study on pulmonary health.

— La Jolla Light staff contributed to this report. ◆