E-Cigarettes Compromise Gut Barrier

Touted by makers as a healthier alternative to traditional nicotine cigarettes, new research indicates the chemicals found in e-cigarettes disrupt the gut barrier and trigger inflammation in the body, potentially leading to a variety of health concerns. The study—led by researchers at the University of California in San Diego—was published in iScience. 

"The gut lining is an amazing entity. It is comprised of a single layer of cells that are meant to seal the body from the trillions of microbes, defend our immune system, and at the same time allow absorption of essential nutrients," said lead researcher Pradipta Ghosh. "Anything we eat or drink, our lifestyle choices in other words, has the ability to impact our gut microbes, the gut barrier and overall health. Now we know that what we smoke, such as e-cigarettes, negatively impacts it as well."

The researchers found that two chemicals used as a base for all e-cigarette liquid vapor, propylene glycol and vegetable glycerol, were the cause of inflammation. "Numerous chemicals are created when these two are heated to generate the fumes in vaping that cause the most damage, for which there are no current regulations," said Ghosh. "The safety of e-cigarettes have been debated fiercely on both sides. Nicotine content, and its addictive nature, has always been the major focus of those who argue against its safety, whereas lack of chemicals in the carcinogens that are present in the cigarette smoke has been touted by the makers of e-cigarettes when marketing these products as a 'healthy alternative.' In reality, it's the chemicals making up the vapor liquid that we should be more concerned about as they are the cause of gut inflammation."

For the study, the team used 3D models of human intestinal tracts generated from patient cells and examined what happens when e-cigarette vapors enter the gut lining. Researchers validated the findings using mice models of vaping. To produce the 3D gut organoids, the researchers collected stem cells from patients' biopsies during colonoscopies and grew them in vitro. The stem cells differentiated into the four different cell types that make up the gut lining. The team then exposed the organoids to e-cigarette liquid vapor, mimicking the frequency of a chronic vaper. They noted that epithelial tight conjunction markers, which are zipper-like proteins that form the gut's first physical barrier, began to break or loosen, causing pathogens from the vapor to seep into the surrounding immune system, wreaking havoc on protective epithelial cells that lie just beneath.