You Have Taste Buds in Your Intestines, and They Know When You Have Worms

The hatching larva of a Toxocara intestinal worm. Scientists have identified a new way that the body identifies and responds to parasites in the gut. Catalina Maya Rendón, Sustainable Sanitation Alliance (SuSanA)/Flickr

If you're eating right now, you may want to take a break to digest this bit of news: You have cells a lot like taste buds in your digestive system, and they're hunting for worms.

Tuft cells, as they're called, get their name from their stiff bristles, which stick out like clumps of brush from the intestinal wall. Researchers first noted them in 1956, but as recently as 2012 they were still something of a mystery. Now, three studies published nearly simultaneously have found that they play an important role in the immune system, alerting the body to resist when intestinal worms, also called helminths, show up. The latest was published February 4 in the journal Science.

"We were intrigued when we heard that there were taste-chemosensory cells in the intestines," says Wendy Garrett, associate professor of immunology and infectious diseases at the Harvard School of Public Health and the corresponding author of the study. "We made a lot of jokes in the lab."

Rest assured, the tuft cells in your gut don't send taste sensations to the brain the way those on our tongues do. That's why Garrett prefers to call them taste-chemosensors; cells that use the same mechanism as taste buds do to detect chemicals and then tell other parts of the body about them. "We found that they're responding to a spectrum of parasites," she says. "We looked at these beasties and we found that the cells respond to all of them. They can sense them and coordinate a type-2 immune response," which is when the body goes looking for a fight after becoming infected.

Garrett's team looked specifically at the cells' communication lines. They gave helminths to regular mice as well as to mice genetically engineered without key proteins tuft cells use to send messages to other cells. Five weeks later they found significantly more worms in the deficient mice than they did in the control mice. Normal mice given worms also produced extra tuft cells and increased levels of interleukin-25, a protein known to trigger immune system responses.

This has been a hot topic for research lately, with several groups studying it independently. A study on the same topic published in Nature in January saw similar results, reporting in part that mice without tuft cells were unable to mount an immune response to helminths. A second study, published in that same issue, also found that a worm infection in mice caused tuft cells to produce more interleukin-25 and to swell in number.

This probably isn't the last word on what exactly tuft cells do in the body. And it's just a part of a much larger investigation of how our bodies interact with the microbes and parasites that live inside it. As Garrett puts it, she and her fellow researchers are asking the gut and the microbiome, "How do you know each other are there?"