The Role of Taste Receptors in Airway Innate Immune Defense

Alan Workman,Edward Kuan,Neil Patel,Noam Cohen,Ryan Carey

doi:10.3390/sinusitis3020006

Abstract

Bitter (T2R) and sweet (T1R) taste receptors are expressed in the upper airway, where they play key roles in antimicrobial innate immune defense. Bitter bacterial products are detected by taste receptors on ciliated cells and solitary chemosensory cells, resulting in downstream nitric oxide and antimicrobial peptide release, respectively. Genetic polymorphisms in taste receptors contribute to variations in T1R and T2R functionality, and phenotypic differences correlate with disease status and disease severity in chronic rhinosinusitis (CRS). Correspondingly, there are also subjective bitter and sweet taste differences between patients with CRS and individuals without CRS across a number of compounds. The ability to capture these differences with a simple and inexpensive taste test provides a potentially useful diagnostic tool, while bitter compounds themselves could potentially serve as therapeutic agents. The present review examines the physiology of airway taste receptors and the recent literature elucidating the role taste receptors play in rhinologic disease.

Highlights

Taste receptors are typically associated with oral sensory perception as an adaptive mechanism for detecting energy rich foods as well as poisons and other unpalatable compounds
Bitter taste receptors are a specific subset of taste receptors that classically respond to toxins, chemicals, and other aversive products that can be detrimental to organismal health
Bitter taste receptors mediate rapid antimicrobial nitric oxide or β-defensin responses in the presence of bacterial compounds, while sweet taste receptors attenuate these responses at higher levels of glucose

Summary

Introduction

Taste receptors are typically associated with oral sensory perception as an adaptive mechanism for detecting energy rich foods as well as poisons and other unpalatable compounds. Bitter taste receptors are a specific subset of taste receptors that classically respond to toxins, chemicals, and other aversive products that can be detrimental to organismal health. Recent research has identified taste receptors in many other anatomic compartments of the body with a variety of functions extending far beyond the canonical sensory capacity of the tongue [1,2,3,4,5,6]. This review will examine the role of bitter and sweet taste receptors that are expressed in the airway, and the important roles that these taste receptors play in innate immune defense [8,9]

Taste Receptor Physiology

Bitter Taste Receptors in the Airway

Bitter Taste Receptors on Ciliated Cells

Taste Receptors on Solitary Chemosensory Cells

Bitter

Diagnostics and Therapeutics

Findings

Conclusions