Role of Taste Receptors in Innate Immunity and Oral Health

Abstract

Taste receptors are receptor proteins that detect ligands belonging to the 5 taste modalities: sweet, bitter, sour, salty, and umami. Taste receptors are not restricted to taste cells in taste buds; rather, they are distributed throughout the entire body. For example, solitary chemosensory cells (SCCs) and tuft cells express taste signal proteins and are present in several mucosae. In the airways, SCCs sense bacteria, allergens, viruses, and noxious stimuli and drive evasive behavior, neuroinflammation, and antibacterial responses. In the gut, tuft cells detect helminth infection and bacterial dysbiosis and initiate type II immune responses characterized by tissue remodeling. In the gingiva, SCCs detect oral pathogenic bacteria, evoke innate immune responses and release antimicrobial compounds in the epithelium, and regulate the microbiome composition. This review summarizes the most recent research on extragustatory taste receptors and their function in antibacterial defense. We also discuss how these findings have provided insights into the development of potential therapeutic strategies for mucosal bacterial infection and dental diseases.

Genetic variants in taste genes play a role in oral microbial composition and severe early childhood caries

“…TAS2R3 , -5, and -60 are also expressed in multiple oral cells. 19 To our knowledge, this is the first study to suggest an association between TAS2R5 and TAS2R60 variants in S-ECC risk or protection. A recent genome-wide association study ( N = 3,686) including a multiethnic cohort identified a suggestive association between dental caries in permanent dentition and a locus near TAS2R38, TAS2R3, TAS2R4, and TASR25 on chromosome 7.…”

“…There is evidence that this Ca 2+ signal stimulates the production of nitric oxide (NO) by epithelial cells, which besides having direct antibacterial and physiological effects, also enhances macrophage phagocytosis. 17 , 18 , 19 The decrease in cAMP level after activation of T2Rs may also contribute to phagocytosis. 18 In a study using knockout mice, it was shown that defects in taste signaling components can affect oral bacterial load and diversity.…”

The Anti-Inflammatory Effects of Iberin on TNF-α-Stimulated Human Oral Epithelial Cells: In Vitro Research

“…T2R agonists induce TNF-α, IL-6, IL-8 and beta-defensin2 production in GECs [ 27 , 28 ]. These reports indicate that in the oral cavity, taste receptors are actively involved in the innate response by recognizing bacterial components [ 29 ]. In addition, isothiocyanates such as iberin may bind to bitter taste receptors in the oral cavity and exert bioactive effects.…”

Inhibitory gating of thalamocortical inputs onto rat gustatory insular cortex

“…This difference in inhibitory modulation between GC and other sensory cortex may carry important functional significance as they may explain the uniquely long-lasting firing dynamics observed for taste responses in GC. The nature of the taste stimulus, which engages complex components including peripheral taste detection by taste receptor cells on the tongue, palate and gums, as well as retronasal activation of receptors in the posterior portion of the mouth and receptors positioned in the early digestive tract (Fujita, 1991;Tizzano et al, 2011;Treesukosol et al, 2011;Samuelsen and Fontanini, 2017;Blankenship et al, 2019;Xi et al, 2022), is likely to engage the taste cortical circuit differently compared to other sensory systems. The distinctive properties of the VPMpc input may endow this thalamocortical system with the ability to support the complex input integration and circuit dynamics characterizing GC's responsiveness to the gustatory experience.…”