Tuesday, October 23, 2012

Immune system can 'taste' when our body is invaded

Taste receptors on our tongue are very handy, because they sample our food and process that information, after which it is sent to the brain. We then become aware of what is in our mouth, and that tells us something about whether we should proceed with swallowing or not. However, the taste receptors apparently do more than just discern food choices: scientists found that the immune system uses them to detect presence of foreign invaders, in order to swiftly produce toxins to kill them.

Our tongue has the ability to discern various flavours, including the taste of bitter. Those same receptors are also present in the upper airway tract that goes down to the lungs. There, they do more than just detect bitter flavours, according to a group of scientists from the University of Pennsylvania. The receptors were able to detect the presence of a certain bacterium and respond with the release of toxic substances.

The scientists derived sinus cells from patients that underwent surgery and exposed them to the bacterial strain Pseudomonas aeruginosa, a variety that is often found in the airway tract and is known to cause pneumonia. When the cells came into contact with the microbes, they released nitric oxide, which is harmful to bacterial cells. It therefore appears that these bitter receptors in the upper airway tract form some kind of innate immune defence.

Taste defence
By linking bitter receptors to immune response, the scientists may have found an explanation for the fact why some people have a weakened response to some bacterial infections. It is known that some people are not that well equipped to taste bitter, and this may correspond with the power of the immune response during a Pseudomonas infection.

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