Chronic e-cigarette use triggers brain, heart & colon inflammation in mice
New research from a team at the University of California San Diego School of Medicine has investigated the effects of chronic pod-based e-cigarette use on inflammation in the brain, heart, lungs and colon. The extensive mouse studies found a variety of raised inflammatory markers in different organs depending on e-cigarette flavor, and neuroinflammation was the most prominent adverse effect.
The new research is the first to robustly investigate the effects of pod-based e-cigarette devices, specifically popular JUUL products. Laura Crotty Alexander, senior author on the new study, explained most prior e-cig studies have focused on older devices such as vape pens.
“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 Crotty Alexander.
To explore the effects of using these products for long periods of time the researchers exposed young mice to aerosols from two JUUL flavors (mint and mango). The animals were exposed to e-cig aerosols for 20-minute stretches, three times a day, for up to 12 weeks.
After three months of exposure the most significant inflammatory markers were found in the animals' brains. Elevated signs of inflammation were particularly concentrated in a brain region called the nucleus accumbens.
This brain region is known to play a role in behavior modification, in particular influencing anxious or depressive behaviors. The researchers are cautious to stress their study did not involve tracking behavioral changes in the animals, so at this stage the effects of this kind of e-cigarette exposure on mental health is purely hypothetical.
"Many JUUL 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," hypothesized Crotty Alexander.
Interestingly, the researchers also found significant differences in inflammatory gene expressions between the two different JUUL flavors. The inflammatory patterns between the flavors were particularly different in the colon and heart. The researchers suggest this indicates there are fundamental differences in the biological effects of different chemical flavorings and more work is needed to understand the impact of these non-nicotine components.
"This was a real surprise to us," said Crotty Alexander. "This shows us that the flavor chemicals themselves are also causing pathological changes.”
The researchers are up-front about the limitations of this kind of animal research. Exposing the whole body of animals to e-cigarette aerosols for 20 minute stretches three times a day is not entirely analogous to the way humans inhale e-cig vapors. And three months of exposure is not exactly akin to human chronic use over multiple years.
However, this kind of research does help scientists find focus for future studies and offers clues to what kinds of deleterious health effects we should be keeping an eye out for in humans. In this instance the findings indicate chronic use of pod-based e-cigarettes may alter the inflammatory state of several different organs in the human body.
“Our findings suggest that chronic inhalation of chemicals within e-cigarette aerosols can lead to inflammatory changes across multiple organ systems,” the researchers concluded in the new study. “JUUL users may unwittingly expose themselves to increased neurologic, colonic and cardiac risk. Further research is greatly needed to better understand the long-lasting effects of vaping.”
The new study was published in the journal eLife.
Source: UC San Diego