Beyond flavor perception: The role of the taste receptor family in immunity.

Taste receptor family 1 (T1R) and taste receptor family 2 (T2R) are G protein-coupled receptors (GPCRs) responsible for sweet, umami, and bitter taste perception. Their widespread ectopic expression of T1Rs and T2Rs in extraoral tissues suggest important physiological functions beyond taste. However, their roles in immune regulation and mucosal immunity have not been comprehensively summarized. We aimed to review the current evidence on the roles of T1Rs and T2Rs in immune cell function, respiratory and intestinal mucosal immunity, and disease susceptibility. Relevant studies investigating the expression, signaling mechanisms, and immunological functions of T1Rs and T2Rs were critically reviewed and synthesized. Current evidence indicates that T1Rs and T2Rs regulate immune cell activity, including inflammatory responses, phagocytosis, and antimicrobial defense. In the respiratory and intestinal mucosa, these receptors function as chemosensory sentinels that detect microbial or dietary stimuli and initiate innate immune responses. In addition, receptor polymorphisms, particularly in TAS2R38, are associated with disease susceptibility and clinical outcomes. T1Rs and T2Rs are emerging as potential therapeutic targets for immune-related diseases. However, further studies are needed to identify endogenous ligands, validate findings in primary human cells, and support future clinical translation.