Bitter and sweet taste receptors in the respiratory epithelium in health and disease

Abstract

Taste receptors on the tongue communicate information to the brain about the nutrient content or potential toxicity of ingested foods. However, recent research has now shown that taste receptors are also expressed far beyond the tongue, from the airway and gastrointestinal epithelia to the pancreas and brain. The functions of many of these so-called extraoral taste receptors remain unknown, but emerging basic science and clinical evidence suggests that bitter and sweet taste receptors in the airway are important in sensing bacteria and regulating innate immunity. This review focuses on the role of bitter and sweet taste receptors in human airway innate immunity and the potential clinical relevance to airway infections. The T2R38 bitter taste receptor in sinonasal cilia detects bitter bacterial quorum-sensing molecules and activates nitric oxide-dependent innate immune responses. Polymorphisms that underlie T2R38 functionality also appear to be involved in susceptibility to upper respiratory infection and chronic rhinosinusitis (CRS). Bitter and sweet receptors in specialized sinonasal solitary chemosensory cells control antimicrobial peptide secretion, which may have important implications for airway infections in CRS patients as well as patients with diabetes mellitus. Future research on taste receptors in the airway has tremendous potential to identify immune mechanisms involved in host-pathogen interactions and thus reveal novel therapeutic targets.

New Insights into Upper Airway Innate Immunity

“…35 In the airway, T2Rs and sweet taste receptors (T1R) have recently been demonstrated to serve a defensive role that guards the airway against infection. 77 The discovery of T2Rs in sinonasal epithelial cells was quite interesting to researchers, given the ability of T2Rs to detect the presence and defend against the ingestion of harmful compounds in the oral cavity. 78 In humans, there are ϳ25 functional isoforms of T2Rs.…”

Will chronic e-cigarette use cause lung disease?

“…Thus, they play a role in detecting noxious inhalants and expelling them from the airways due to increased rates of mucociliary clearance. Nasal mucosa have been reported to express both sweet receptors (T1Rs) as well as T2Rs in special nonciliated epithelial cells called solitary chemosensory cells (SCCs) (90). SCCs in the nasal epithelium harbor these receptors along with known components of the taste receptor signaling pathway and trigeminal nerve innervation.…”

Taste receptors in the gut – A new target for health promoting properties in diet

“…After that, the existence of taste signalling pathways have been reported in a variety of other tissues (Behrens & Meyerhof, 2011;Bezencon, le Coutre, & Damak, 2007;Dotson et al, 2008;Dyer, Salmon, Zibrik, & Shirazi-Beechey, 2005;Fehr et al, 2007;Finger et al, 2003). Most research concerning the TAS1R-family has been focused on the enteroendocrine cells in the gut (Depoortere, 2014), but functional TAS1Rs have also been reported in the pancreas (Kyriazis, Soundarapandian, & Tyrberg, 2012;Nakagawa et al, 2009), the brain (Ren, Zhou, Terwilliger, Newton, & de Araujo, 2009), adipose tissue (Masubuchi et al, 2013), the airways (Lee & Cohen, 2014), the testis (Mosinger et al, 2013), muscle tissue (Kokabu et al, 2015), and liver (Taniguchi, 2004). TAS2Rs have been found in the gut, the airways, the brain, the heart, in vascular endothelium, the thyroid, the kidney, the testis, the immune system, the thymus, in bone marrow, breast epithelium and skin keratinocytes (Roura et al, 2016;Wolfle et al, 2016).…”