It might seem useless to have taste receptors in a part of the body that never touches food. But not only do we have taste receptors in our lungs, scientists might be able to employ them to treat asthma and other diseases in which airflow to the lungs is impeded, according to a new study.
These taste receptors are activated by bitter-tasting compounds, and can be activated to open the airway in an unprecedented way, at least in studies on mice.
"We found a series of drugs that work better than any other drug that we have," for asthma or chronic obstructive pulmonary disease (COPD), said study researcher Dr. Stephen Liggett, professor of medicine and physiology at the University of Maryland School of Medicine.
In asthma, the muscles surrounding the airway tighten, limiting the amount of air that can reach the lungs and causing wheezing. COPD is caused by inflammation and narrowing of the airway.
Researchers might be able to turn bitter-tasting compounds into new drugs for these conditions. New treatments are needed because "only about half of the patients with asthma or COPD have good control of their disease," Liggett said.
An unexpected find
Liggett and his colleagues unexpectedly discovered taste receptors in human lungs in 2008, while looking for genes of receptors in the human body. This is the first published work that specifically discusses the receptors.
While the lung's taste receptors are similar as those in the tongue, they are not involved in our sense of taste. These receptors are not bunched into buds, as they are on the tongue, and they do not communicate sensations of taste to the brain.
The researchers first thought these receptors might help protect the body against poisons by constricting the airway when they detected certain compounds in the air — many poisonous compounds derived from plants are bitter tasting. But they found the opposite was true.
They tested bitter tasting compounds, such as quinine and chloroquine (both drugs used to treat malaria), on tissues from human and mouse airways, as well as in asthmatic mice. These compounds relaxed the airways. The bitter-tasting compounds were about three times as effective as the drug albuterol, the most-prescribed drug for asthma worldwide, Liggett told MyHealthNewsDaily.
New asthma drugs
The researchers caution their findings do not mean eating bitter foods will help with asthma. Rather, aerosolized versions of such compounds might serve as drugs that could be inhaled into the lungs, the researchers say.
Drug companies could have a lot of compounds to choose from, because there are more than 10,000 synthetic or natural compounds known to activate these receptors, Liggett said.
"That's a very unusual situation for drug development to have so many potential drugs available for screening, so that we would ultimately find the best one for an inhalation type of medicine for asthma," he said.
The study was published Oct. 24 in the journal Nature Medicine.