Bitter Tastes Initiate Our Immune System Response

Submitted by Aspergillus Administrator on 6 November 2012

It has long been suspected that we evolved to taste bitter substances and generally reject them in order to be able to identify foods that had ‘gone off’ after being infected with micro-organisms, but does it go further than that?

Researchers have discovered that when we eat bitter substances it can actively initiate our immune response in our upper airways, and those who taste bitterness particularly well also fight off infection of our upper respiratory tract (upper throat and  sinuses) particularly well. The infecting agents in this study were bacteria but foods spoiled by fungi are likely to have a similar bitter taste.
About 25% of us cannot taste bitterness  very well and it follows that these people may not fight off infection efficiently and thus be prone to chronic sinusitis.

Quoting from the Penn University News Report:

They found that one of the bitter taste receptors that functions in upper airway cells, known as T2R38, acts as a type of “security guard” for the upper airway by detecting molecules that a certain class of bacteria secretes.  “These molecules instruct other bacteria to form a biofilm, which helps harbor the bacteria. From previous work, we know that these biofilms spur the immune system to mount an over-exuberant inflammatory response that can lead to sinusitis symptoms.  When the T2R38 receptor detects these molecules, it activates local defensive maneuvers to increase mucus clearance and kill the invading bacteria. It’s really like modern warfare – intercept the enemies’ early communications to thwart their plans and win the battle,” Cohen said, who is also the director of the Rhinology Research Lab at Penn.

Through the cultures, the research team demonstrated that super-tasters detect very small concentrations of the offending molecules, while non-tasters and the middle-ground individuals require 100 times more of the molecule for detection.  The research team also examined the patients that the original sinus tissue samples were collected from. They found that none of the super tasters were infected with the specific type of bacteria that are detected by the T2R38 receptor, known as a gram-negative bacteria.

“Based on these findings, we believe that other bitter taste receptors in the airway perform the same “guard duty” function for early detection of attack by different types of bacteria, and we hope to translate these findings into personalized diagnostics for patients with chronic rhinosinusitis,” Cohen says.

News report at Penn University


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