Lungs can 'taste' dangerous bacteria, researchers say

Posted: 10/25/2010

From The Wall Street Journal:

The same taste buds we have on the tongue to detect bitterness also exist on lung muscle so that the airways can "taste" dangerous illness-causing bacteria, according to new research published Sunday that could lead to better treatments for respiratory conditions.

When the taste receptors in the lungs detect these bugs that cause pneumonia and other serious infections, the muscle relaxes and the airways expand. This happens, presumably, to allow a person to breathe more easily, and to clear the bacteria and related debris out of the airway to keep the bacteria from progressing to a more serious infection, according to the small but surprising study that appears in the journal Nature Medicine.

Researchers had expected the lung muscle to constrict when the receptors were activated, which would make it harder for the person to breathe and thus let in less of the bacteria. This unexpected relaxation effect suggests that developing drugs to target these taste receptors could lead to more effective treatments of illnesses where airways become inflamed and constrict, such as such as asthma and chronic obstructive pulmonary diseases, said Stephen Liggett, senior author on the study and a professor at the University of Maryland School of Medicine.

Bedrich Mosinger, a taste-receptor researcher at the Monell Chemical Senses Center in Philadelphia who wasn't involved in the study, called the findings "strange and surprising" but plausible. Bitter taste receptors on the tongue alert the brain to the possibility that a poisonous plant, which is often bitter, could be ingested. Finding a taste receptor on muscle deep in an organ is highly unusual, Dr. Mosinger said.

Many medicines already on the market, such as quinine for malaria, contain compounds that would trigger the bitter taste receptors. "This gives us a real opportunity to fast-track one of these compounds" as a new medicine for respiratory illnesses, said Dr. Liggett, a pulmonologist.

The researchers, from the University of Maryland and Johns Hopkins University, studied the receptors in the lungs of mice, as well as the lung tissue from 10 people, some with normal lungs and others with disease, and found that all had these receptors that responded to bitter tastes.

The finding "suggests that nature has designed multiple pathways to prevent things from going down the wrong way," said Y.S. Prakash, an airway biologist at the Mayo Clinic in Rochester, Minn., who wasn't involved in the work.

Dr. Liggett said that because bitter taste receptors are so effective at opening the airways, he estimated that a drug that targets taste receptors could be three times as effective as current respiratory medications on the market.

His group is now screening some of these compounds for ones that are potentially safe and effective and can be used in spray form rather than a pill to activate receptors in the lung.

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