Hospital of the University of Pennsylvania
Taste receptors were first identified on the tongue, where they initiate a signaling pathway that communicates information to the brain about the nutrient content or potential toxicity of ingested foods. However, recent research has shown that taste receptors are also expressed in a myriad of other tissues, from the airway and gastrointestinal epithelia to the pancreas and brain. The functions of many of these extra-oral taste receptors remain unknown, but emerging evidence suggests that taste receptors in the airway are important sentinels of innate immunity. We will discuss our recent findings demonstrating that a subset of bitter taste receptors expressed in human ciliated cells regulate rapid nitric oxide production in response to microbial factors. We have also demonstrated that bitter and sweet taste receptors expressed in human sinonasal solitary chemosensory cells regulate a complimentary arm of innate immunity, the release of antimicrobial peptides. Lastly, common genetic polymorphisms of the taste receptor genes that render these receptors non-functional appear to result in a weakened respiratory innate defense contributing to therapeutically recalcitrant upper respiratory infections.