Differential Effect of TRPV1 Modulators on Neural and Behavioral Responses to Taste Stimuli.

In our diet, we ingest a variety of compounds that are TRPV1 modulators. It is important to understand if these compounds alter neural and behavioral responses to taste stimuli representing all taste qualities. Here, we will summarize the effects of capsaicin, resiniferatoxin, cetylpyridinium chloride, ethanol, nicotine, -geranyl cyclopropylcarboxamide, Kokumi taste peptides, pH, and temperature on neural and behavioral responses to taste stimuli in rodent models and on human taste perception.

Possible roles of phytochemicals with bioactive properties in the prevention of and recovery from COVID-19.

Introduction: There have been large geographical differences in the infection and death rates of COVID-19. Foods and beverages containing high amounts of phytochemicals with bioactive properties were suggested to prevent contracting and to facilitate recovery from COVID-19. The goal of our study was to determine the correlation of the type of foods/beverages people consumed and the risk reduction of contracting COVID-19 and the recovery from COVID-19.

Primary Culture of the Human Olfactory Neuroepithelium and Utilization for Henipavirus Infection In Vitro.

The olfactory receptor neurons (ORNs) are a unique cell type involved in the initial perception of odors. These specialized epithelial cells are located in the neuroepithelium of the nasal cavities and directly connect the nasal cavity with the central nervous system (CNS) via axons, which traverse the cribriform plate to synapse within the olfactory bulb. ORNs are derived from precursor cells that lie adjacent to the basal lamina of the olfactory epithelium.

Coronavirus infection in chemosensory cells.

Clinical manifestations of human coronavirus (HCoV)-related diseases are mostly related to the respiratory system, although secondary complications such as headache, anosmia, ageusia, and myalgia have been reported. HCoV infection and replication in chemosensory cells associated with ageusia and anosmia is poorly understood. Here, we characterized HCoV-OC43 and SARS-CoV-2 infection in two types of chemosensory cells, olfactory and taste cells, with their unique molecular and histological characteristics.

Reprogramming cultured human fungiform (HBO) taste cells into neuron-like cells through in vitro induction.

Human taste cells are a heterogeneous population of specialized epithelial cells that are constantly generated from progenitor taste cells. Type I and type III taste cells express some neural markers, and studies have reported that direct innervation by neurons is not required for taste cell development. To our knowledge, no previous study has demonstrated that taste cells can differentiate into neuron-like cells or any other non-taste cell type.

Relationship between ENaC Regulators and SARS-CoV-2 Virus Receptor (ACE2) Expression in Cultured Adult Human Fungiform (HBO) Taste Cells.

In addition to the α, β, and γ subunits of ENaC, human salt-sensing taste receptor cells (TRCs) also express the δ-subunit. At present, it is not clear if the expression and function of the ENaC δ-subunit in human salt-sensing TRCs is also modulated by the ENaC regulatory hormones and intracellular signaling effectors known to modulate salt responses in rodent TRCs. Here, we used molecular techniques to demonstrate that the G-protein-coupled estrogen receptor (GPER1), the transient receptor potential cation channel subfamily V member 1 (TRPV1), and components of the renin-angiotensin-aldosterone system (RAAS) are expressed in δ-ENaC-positive cultured adult human fungiform (HBO) taste cells.

Inhibition of Bitter Taste from Oral Tenofovir Alafenamide.

Children have difficulty swallowing capsules. Yet, when presented with liquid formulations, children often reject oral medications due to their intense bitterness. Presently, effective strategies to identify methods, reagents, and tools to block bitterness remain elusive.

Recent Smell Loss Is the Best Predictor of COVID-19 Among Individuals With Recent Respiratory Symptoms.

In a preregistered, cross-sectional study, we investigated whether olfactory loss is a reliable predictor of COVID-19 using a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0-100 visual analog scales (VAS) for participants reporting a positive (C19+; n = 4148) or negative (C19-; n = 546) COVID-19 laboratory test outcome. Logistic regression models identified univariate and multivariate predictors of COVID-19 status and post-COVID-19 olfactory recovery.

More Than Smell-COVID-19 Is Associated With Severe Impairment of Smell, Taste, and Chemesthesis.

Recent anecdotal and scientific reports have provided evidence of a link between COVID-19 and chemosensory impairments, such as anosmia. However, these reports have downplayed or failed to distinguish potential effects on taste, ignored chemesthesis, and generally lacked quantitative measurements. Here, we report the development, implementation, and initial results of a multilingual, international questionnaire to assess self-reported quantity and quality of perception in 3 distinct chemosensory modalities (smell, taste, and chemesthesis) before and during COVID-19.

Zika virus infection in chemosensory cells.

Zika virus (ZIKV) is an emerging virus belonging to the genus Flavivirus. ZIKV infection is a significant health concern, with increasing numbers of reports of microcephaly cases in fetuses and Guillain-Barré syndrome (GBS) in adults. Interestingly, chemosensory disturbances are also reported as one of the manifestations of GBS.

Novel GPR120 agonist TUG891 modulates fat taste perception and preference and activates tongue-brain-gut axis in mice.

GPR120 is implicated as a lipid receptor in the oro-sensory detection of dietary fatty acids. However, the effects of GPR120 activation on dietary fat intake or obesity are not clearly understood. We investigated to determine whether the binding of TUG891, a novel GPR120 agonist, to lingual GPR120 modulates fat preference in mice.

Suppression of Zika Virus Infection in the Brain by the Antiretroviral Drug Rilpivirine.

Zika virus (ZIKV) infection is associated with microcephaly in neonates and Guillain-Barré syndrome in adults. ZIKV produces a class of nonstructural (NS) regulatory proteins that play a critical role in viral transcription and replication, including NS5, which possesses RNA-dependent RNA polymerase (RdRp) activity. Here we demonstrate that rilpivirine (RPV), a non-nucleoside reverse transcriptase inhibitor (NNRTI) used in the treatment of HIV-1 infection, inhibits the enzymatic activity of NS5 and suppresses ZIKV infection and replication in primary human astrocytes.

Mammalian Taste Cells Express Functional Olfactory Receptors.

The peripheral taste and olfactory systems in mammals are separate and independent sensory systems. In the current model of chemosensation, gustatory, and olfactory receptors are genetically divergent families expressed in anatomically distinct locations that project to disparate downstream targets. Although information from the 2 sensory systems merges to form the perception of flavor, the first cross talk is thought to occur centrally, in the insular cortex.

Arginyl dipeptides increase the frequency of NaCl-elicited responses via epithelial sodium channel alpha and delta subunits in cultured human fungiform taste papillae cells.

Salty taste is one of the five basic tastes and is often elicited by NaCl. Because excess sodium intake is associated with many health problems, it could be useful to have salt taste enhancers that are not sodium based. In this study, the regulation of NaCl-induced responses was investigated in cultured human fungiform taste papillae (HBO) cells with five arginyl dipeptides: Ala-Arg (AR), Arg-Ala (RA), Arg-Pro (RP), Arg-Glu (RE), and Glu-Arg (ER); and two non-arginyl dipeptides: Asp-Asp (DD) and Glu-Asp (ED).

Hendra and Nipah Virus Infection in Cultured Human Olfactory Epithelial Cells.

Henipaviruses are emerging zoonotic viruses and causative agents of encephalitis in humans. However, the mechanisms of entry into the central nervous system (CNS) in humans are not known. Here, we evaluated the possible role of olfactory epithelium in virus entry into the CNS.

Cyclic-AMP regulates postnatal development of neural and behavioral responses to NaCl in rats.

During postnatal development rats demonstrate an age-dependent increase in NaCl chorda tympani (CT) responses and the number of functional apical amiloride-sensitive epithelial Na+ channels (ENaCs) in salt sensing fungiform (FF) taste receptor cells (TRCs). Currently, the intracellular signals that regulate the postnatal development of salt taste have not been identified. We investigated the effect of cAMP, a downstream signal for arginine vasopressin (AVP) action, on the postnatal development of NaCl responses in 19-23 day old rats.

ERK1/2 activation in human taste bud cells regulates fatty acid signaling and gustatory perception of fat in mice and humans.

Obesity is a major public health problem. An in-depth knowledge of the molecular mechanisms of oro-sensory detection of dietary lipids may help fight it. Humans and rodents can detect fatty acids via lipido-receptors, such as CD36 and GPR120.

CD36- and GPR120-mediated Ca²⁺ signaling in human taste bud cells mediates differential responses to fatty acids and is altered in obese mice.

Background & Aims: It is important to increase our understanding of gustatory detection of dietary fat and its contribution to fat preference. We studied the roles of the fat taste receptors CD36 and GPR120 and their interactions via Ca(2+) signaling in fungiform taste bud cells (TBC).

Methods: We measured Ca(2+) signaling in human TBC, transfected with small interfering RNAs against messenger RNAs encoding CD36 and GPR120 (or control small interfering RNAs).

Volatile biomarkers from human melanoma cells.

Dogs can identify, by olfaction, melanoma on the skin of patients or melanoma samples hidden on healthy subjects, suggesting that volatile organic compounds (VOCs) from melanoma differ from those of normal skin. Studies employing gas chromatography-mass spectrometry (GC-MS) and gas sensors reported that melanoma-related VOCs differed from VOCs from normal skin sources. However, the identities of the VOCs that discriminate melanoma from normal skin were either unknown or likely derived from exogenous sources.

Primary culture of mammalian taste epithelium.

Establishment of primary and immortalized cultures of many cell types has facilitated efforts to understand the signals involved in proliferation and differentiation and yielded tools to rapidly assay new molecules targeting specific receptor pathways. Taste cells are specialized sensory epithelial cells which reside within taste buds on the lingual epithelium. Only recently have successful culturing protocols been developed which maintain essential molecular and functional characteristics.

Primary culture of the human olfactory neuroepithelium.

The central cell type involved in the initial perception of odors and transduction of the sensory signal are the olfactory receptor neurons (ORNs) located in the olfactory neuroepithelium of the nasal cavities. The olfactory epithelium is a unique system similar to the neuroepithelium of the embryonic neural tube, in which new neurons are continually generated throughout adult life. Olfactory neurons are derived from precursor cells that lie adjacent to the basal lamina of the olfactory epithelium; these precursor cells divide several times and their progeny differentiate into mature sensory neurons throughout life.

Characterization of human fungiform papillae cells in culture.

The ability to maintain human fungiform papillae cells in culture for multiple cell cycles would be of considerable utility for characterizing the molecular, regenerative, and functional properties of these unique sensory cells. Here we describe a method for enzymatically isolating human cells from fungiform papillae obtained by biopsy and maintaining them in culture for more than 7 passages (7 months) without loss of viability and while retaining many of the functional properties of acutely isolated taste cells. Cells in these cultures exhibited increases in intracellular calcium when stimulated with perceptually appropriate concentrations of several taste stimuli, indicating that at least some of the native signaling pathways were present.