Expression of Bitter Taste Receptors and Solitary Chemosensory Cell Markers in the Human Sinonasal Cavity

Abstract

<jats:title>Abstract</jats:title> <jats:p>Some bitter taste receptors (TAS2R gene products) are expressed in the human sinonasal cavity and may function to detect airborne irritants. The expression of all 25 human bitter taste receptors and their location within the upper airway is not yet clear. The aim of this study is to characterize the presence and distribution of TAS2R transcripts and solitary chemosensory cells (SCCs) in different locations of the human sinonasal cavity. Biopsies were obtained from human subjects at up to 4 different sinonasal anatomic sites. PCR, microarray, and qRT-PCR were used to examine gene transcript expression. The 25 human bitter taste receptors as well as the sweet/umami receptor subunit, TAS1R3, and canonical taste signaling effectors are expressed in sinonasal tissue. All 25 human bitter taste receptors are expressed in the human upper airway, and expression of these gene products was higher in the ethmoid sinus than nasal cavity locations. Fluorescent in situ hybridization demonstrates that epithelial TRPM5 and TAS2R38 are expressed in a rare cell population compared with multiciliated cells, and at times, consistent with SCC morphology. Secondary analysis of published human sinus single-cell RNAseq data did not uncover TAS2R or canonical taste transduction transcripts in multiciliated cells. These findings indicate that the sinus has higher expression of SCC markers than the nasal cavity in chronic rhinosinusitis patients, comprising a rare cell type. Biopsies obtained from the ethmoid sinus may serve as the best location for study of human upper airway taste receptors and SCCs.</jats:p>

Allergic rhinitis

“…The nasal mucosa is densely innervated by adrenergic and cholinergic nerve fibres, and the epithelium is innervated by interdigitating sensory nerve endings, mostly nociceptors (receptors that respond to noxious stimuli) 65 . In addition, nasal chemosensory cells that express bitter taste receptors may reflect a specialized sensory nerve system that reacts to noxious stimuli and bacterial products 66 . Cholinergic and adrenergic nerve fibres are activated through central reflexes initiated at the nasal mucosa by sensory nerves, including nociceptor C fibres.…”

Tuft cells in the pathogenesis of chronic rhinosinusitis with nasal polyps and asthma

“…The analysis of human sinonasal single-cell RNA sequencing data revealed that tuft cell markers are expressed at higher levels in the sinus than in the nasal cavity in patients with CRS, implicating tuft cells in the pathogenesis of CRSwNP. 71 It was further illustrated that SCCs and brush cells proliferate on exposure to aeroallergens, including fungal extracts (Aspergillus fumigatus and Alternaria alternata) 36,39 and after H1N1 influenza virus infection. 72 Recently, a gustducin and DCAMKL1-positive cell population was noted to be increased in human polyp tissue compared with turbinate tissue.…”

Nasal Epithelial Barrier Integrity and Tight Junctions Disruption in Allergic Rhinitis: Overview and Pathogenic Insights

“…Solitary chemosensory cells (SCCs) are found in healthy sinus cavity and turbinate tissues of the human upper airway where they function as epithelial sentinels by detecting pathogenic metabolites and initiate protective immune defense (106). Increased number of SCCs was found in the sinonasal epithelia of chronic rhinosinusitis with nasal polyps patients (107).…”