New research from the Monell Chemical Senses Center in Philadelphia reveals that tumor necrosis factor (TNF), an immune system regulatory protein that promotes inflammation, also helps regulate sensitivity to bitter taste. The finding may provide a mechanism to explain the taste system abnormalities and decreased food intake that can be associated with infections, autoimmune disorders, and chronic inflammatory diseases. In addition to its role in mediating inflammation, TNF has been implicated in the progression of varied diseases ranging from Alzheimer's disease to cancer. "Reduced food intake and associated malnutrition is a significant concern that affects the long-term prognosis of many people who are very ill," said senior author Hong Wang, Ph.D., a molecular biologist at Monell. "Our findings reveal that bitter taste is regulated by the immune system. Specifically, TNF may make sick people more sensitive to bitterness so that foods taste more bitter and less appetizing." Dr. Wang's research focuses on interactions between the taste and immune systems, with the goal of identifying how taste cell function changes in disease states. As part of this effort, previous research from her laboratory had demonstrated that taste buds contain several immune system proteins, including TNF. Because TNF is known to suppress food intake, the current study asked whether TNF affects food intake via the taste system. The findings were published online on April 21, 2015 in the journal Brain, Behavior, and Immunity. To examine whether TNF helps regulate taste responses, the researchers first compared taste responses of normal mice to those of mice engineered to be lacking the gene for TNF (TNF knockout mice).
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