Bioinformatics for Dentistry: A secondary database for the genetics of tooth development.

Genes strictly regulate the development of teeth and their surrounding oral structures. Alteration of gene regulation leads to tooth disorders and developmental anomalies in tooth, oral, and facial regions. With the advancement of gene sequencing technology, genomic data is rapidly increasing. However, the large sets of genomic and proteomic data related to tooth development and dental disorders are currently dispersed in many primary databases and literature, making it difficult for users to navigate, extract, study, or analyze. We have curated the scattered genetic data on tooth development and created a knowledgebase called 'Bioinformatics for Dentistry' (https://dentalbioinformatics.com/). This database compiles genomic and proteomic data on human tooth development and developmental anomalies and organizes them according to their roles in different stages of tooth development. The database is built by systemically curating relevant data from the National Library of Medicine (NCBI) GenBank, OMIM: Online Mendelian Inheritance in Man, AlphaFold Protein Structure Database, Reactome pathway knowledgebase, Wiki Pathways, and PubMed. The accuracy of the included data was verified from supporting primary literature. Upon data curation and validation, a simple, easy-to-navigate browser interface was created on WordPress version 6.3.2, with PHP version 8.0. The website is hosted in a cloud hosting service to provide fast and reliable data transfer rate. Plugins are used to ensure the browser's compatibility across different devices. Bioinformatics for Dentistry contains four embedded filters for complex and specific searches and free-text search options for quick and simple searching through the datasets. Bioinformatics for Dentistry is made freely available worldwide, with the hope that this knowledgebase will improve our understanding of the complex genetic regulation of tooth development and will open doors to research initiatives and discoveries. This database will be expanded in the future by incorporating resources and built-in sequence analysis tools, and it will be maintained and updated annually.

A Transcription Factor Etv1/Er81 Is Involved in the Differentiation of Sweet, Umami, and Sodium Taste Cells.

Taste cells are maintained by continuous turnover throughout a lifetime, yet the mechanisms of taste cell differentiation, and how taste sensations remain constant despite this continuous turnover, remain poorly understood. Here, we report that a transcription factor Etv1 (also known as Er81) is involved in the differentiation of taste cells responsible for the preference for sweet, umami, and salty tastes. Molecular analyses revealed that Etv1 is expressed by a subset of taste cells that depend on Skn-1a (also known as Pou2f3) for their generation and express T1R genes (responsible for sweet and umami tastes) or Scnn1a (responsible for amiloride-sensitive salty taste). Etv1CreERT2/CreERT2 mice express Etv1 isoform(s) but not Etv1 in putative proprioceptive neurons as comparable to wild-type mice, yet lack expression of Etv1 or an isoform in taste cells. These Etv1CreERT2/CreERT2 mice have the same population of Skn-1a-dependent cells in taste buds as wild-type mice but have altered gene expression in taste cells, with regional differences. They have markedly decreased electrophysiological responses of chorda tympani nerves to sweet and umami tastes and to amiloride-sensitive salty taste evoked by sodium cation, but they have unchanged responses to bitter or sour tastes. Our data thus show that Etv1 is involved in the differentiation of the taste cells responsible for sweet, umami, and salty taste preferences.

Taste cell-expressed α-glucosidase enzymes contribute to gustatory responses to disaccharides.

The primary sweet sensor in mammalian taste cells for sugars and noncaloric sweeteners is the heteromeric combination of type 1 taste receptors 2 and 3 (T1R2+T1R3, encoded by Tas1r2 and Tas1r3 genes). However, in the absence of T1R2+T1R3 (e.g., in Tas1r3 KO mice), animals still respond to sugars, arguing for the presence of T1R-independent detection mechanism(s). Our previous findings that several glucose transporters (GLUTs), sodium glucose cotransporter 1 (SGLT1), and the ATP-gated K(+) (KATP) metabolic sensor are preferentially expressed in the same taste cells with T1R3 provides a potential explanation for the T1R-independent detection of sugars: sweet-responsive taste cells that respond to sugars and sweeteners may contain a T1R-dependent (T1R2+T1R3) sweet-sensing pathway for detecting sugars and noncaloric sweeteners, as well as a T1R-independent (GLUTs, SGLT1, KATP) pathway for detecting monosaccharides. However, the T1R-independent pathway would not explain responses to disaccharide and oligomeric sugars, such as sucrose, maltose, and maltotriose, which are not substrates for GLUTs or SGLT1. Using RT-PCR, quantitative PCR, in situ hybridization, and immunohistochemistry, we found that taste cells express multiple α-glycosidases (e.g., amylase and neutral α glucosidase C) and so-called intestinal "brush border" disaccharide-hydrolyzing enzymes (e.g., maltase-glucoamylase and sucrase-isomaltase). Treating the tongue with inhibitors of disaccharidases specifically decreased gustatory nerve responses to disaccharides, but not to monosaccharides or noncaloric sweeteners, indicating that lingual disaccharidases are functional. These taste cell-expressed enzymes may locally break down dietary disaccharides and starch hydrolysis products into monosaccharides that could serve as substrates for the T1R-independent sugar sensing pathways.

The influence of nasal airflow on respiratory and olfactory epithelial distribution in felids.

The surface area of the maxilloturbinals and fronto-ethmoturbinals is commonly used as an osteological proxy for the respiratory and the olfactory epithelium, respectively. However, this assumption does not fully account for animals with short snouts in which these two turbinal structures significantly overlap, potentially placing fronto-ethmoturbinals in the path of respiratory airflow. In these species, it is possible that anterior fronto-ethmoturbinals are covered with non-sensory (respiratory) epithelium instead of olfactory epithelium. In this study, we analyzed the distribution of olfactory and non-sensory, respiratory epithelia on the turbinals of two domestic cats (Felis catus) and a bobcat (Lynx rufus). We also conducted a computational fluid dynamics simulation of nasal airflow in the bobcat to explore the relationship between epithelial distribution and airflow patterns. The results showed that a substantial amount of respiratory airflow passes over the anterior fronto-ethmoturbinals, and that contrary to what has been observed in caniform carnivorans, much of the anterior ethmoturbinals are covered by non-sensory epithelium. This confirms that in short-snouted felids, portions of the fronto-ethmoturbinals have been recruited for respiration, and that estimates of olfactory epithelial coverage based purely on fronto-ethmoturbinal surface area will be exaggerated. The correlation between the shape of the anterior fronto-ethmoturbinals and the direction of respiratory airflow suggests that in short-snouted species, CT data alone are useful in assessing airflow patterns and epithelium distribution on the turbinals.

Comparative Morphology and Histology of the Nasal Fossa in Four Mammals: Gray Squirrel, Bobcat, Coyote, and White-Tailed Deer.

Although the anatomy of the nasal fossa is broadly similar among terrestrial mammals, differences are evident in the intricacies of nasal turbinal architecture, which varies from simple scroll-like to complex branching forms, and in the extent of nonsensory and olfactory epithelium covering the turbinals. In this study, detailed morphological and immunohistochemical examinations and quantitative measurements of the turbinals and epithelial lining of the nasal fossa were conducted in an array of species that include the gray squirrel, bobcat, coyote, and white-tailed deer. Results show that much more of the nose is lined with olfactory epithelium in the smallest species (gray squirrel) than in the larger species. In two species with similar body masses, bobcat and coyote, the foreshortened felid snout influences turbinal size and results in a decrease of olfactory epithelium on the ethmoturbinals relative to the longer canine snout. Ethmoturbinal surface area exceeds that of the maxilloturbinals in all four sampled animals, except the white-tailed deer, in which the two are similar in size. Combining our results with published data from a broader array of mammalian noses, it is apparent that olfactory epithelial surface area is influenced by body mass, but is also affected by aspects of life history, such as diet and habitat, as well as skull morphology, itself a product of multiple compromises between various functions, such as feeding, vision, and cognition. The results of this study warrant further examination of other mammalian noses to broaden our evolutionary understanding of nasal fossa anatomy. Anat Rec, 299:840-852, 2016. © 2016 Wiley Periodicals, Inc.

Conductive olfactory losses in chronic rhinosinusitis? A computational fluid dynamics study of 29 patients.

BACKGROUND: Besides sensorineural factors, conductive impediments likely contribute to olfactory losses in chronic rhinosinusitis (CRS) patients, yet no conclusive evidence exists. We aimed to examine possible conductive factors using computational fluid dynamics (CFD) models. METHODS: A total of 29 CRS patients were assessed via odorant detection thresholds (ODTs), rhinomanometry (nasal resistance [NR]), acoustic rhinometry (minimum-cross-sectional area [MCA]) and computed tomography (CT) staging. CFD simulations of nasal airflow and odorant absorption to olfactory region were carried out based on individual CTs. Biopsies of olfactory epithelium (OE) were collected, cryosectioned, stained, and scored for erosion. RESULTS: Significant correlations to ODTs were found for 3 variables: odor absorption in the olfactory region (r = -0.60, p < 0.01), MCA (r = -0.40, p < 0.05), and CT staging (r = 0.42, p < 0.05). However, significant findings were limited to ODTs of the highly soluble l-carvone. Multiple regression analysis revealed that these variables combined, with the addition of NR, can account for 65% of the total variance in ODTs. CT staging correlated significantly with OE erosion (r = 0.77, p < 0.01) and can replace the latter in the regression with comparable outcomes. Partial correlations suggest the contributions of both conductive and sensorineural variables are more prominent if adjusted for the effects of the other. Olfactory loss and inflammatory factors have strong bilateral involvement, whereas conductive factors are independent between sides. As validation, CFD-simulated NRs significantly correlated with rhinomanometrically assessed NRs (r = 0.60, p < 0.01). CONCLUSION: Both conductive and sensorineural mechanisms can contribute to olfactory losses in CRS. CFD modeling provides critical guidance in understanding the role of conductive impediments in olfactory dysfunction in CRS.

Endocrine taste cells.

In taste cells, taste receptors, their coupled G proteins and downstream signalling elements mediate the detection and transduction of sweet, bitter and umami compounds. In some intestinal endocrine cells, taste receptors and gustducin contribute to the release of glucagon-like peptide 1 (GLP-1) and other gut hormones in response to glucose and non-energetic sweeteners. Conversely, taste cells have been found to express multiple hormones typically found in intestinal endocrine cells, e.g. GLP-1, glucagon, somatostatin and ghrelin. In the present study, by immunohistochemistry, multiple subsets of taste cells were found to express GLP-1. The release of GLP-1 from 'endocrine taste cells' into the bloodstream was examined. In wild-type mice, even after oesophagectomy and vagotomy, oral stimulation with glucose induced an elevation of GLP-1 levels in the bloodstream within 10 min. Stimulation of taste cell explants from wild-type mice with glucose led to the release of GLP-1 into the medium. Knocking out of the Tas1r3 gene did not eliminate glucose-stimulated GLP-1 release from taste cells in vivo. The present results indicate that a portion of the cephalic-phase rise in circulating GLP-1 levels is mediated by the direct release of GLP-1 from taste cells into the bloodstream.

Genetic loss or pharmacological blockade of testes-expressed taste genes causes male sterility.

TAS1R taste receptors and their associated heterotrimeric G protein gustducin are involved in sugar and amino acid sensing in taste cells and in the gastrointestinal tract. They are also strongly expressed in testis and sperm, but their functions in these tissues were previously unknown. Using mouse models, we show that the genetic absence of both TAS1R3, a component of sweet and amino acid taste receptors, and the gustducin α-subunit GNAT3 leads to male-specific sterility. To gain further insight into this effect, we generated a mouse model that expressed a humanized form of TAS1R3 susceptible to inhibition by the antilipid medication clofibrate. Sperm formation in animals without functional TAS1R3 and GNAT3 is compromised, with malformed and immotile sperm. Furthermore, clofibrate inhibition of humanized TAS1R3 in the genetic background of Tas1r3(-/-), Gnat3(-/-) doubly null mice led to inducible male sterility. These results indicate a crucial role for these extraoral "taste" molecules in sperm development and maturation. We previously reported that blocking of human TAS1R3, but not mouse TAS1R3, can be achieved by common medications or chemicals in the environment. We hypothesize that even low levels of these compounds can lower sperm count and negatively affect human male fertility, which common mouse toxicology assays would not reveal. Conversely, we speculate that TAS1R3 and GNAT3 activators may help infertile men, particularly those that are affected by some of the mentioned inhibitors and/or are diagnosed with idiopathic infertility involving signaling pathway of these receptors.

Heterotrimeric G protein subunit Gγ13 is critical to olfaction.

The activation of G-protein-coupled olfactory receptors on the olfactory sensory neurons (OSNs) triggers a signaling cascade, which is mediated by a heterotrimeric G-protein consisting of α, ß, and γ subunits. Although its α subunit, Gαolf, has been identified and well characterized, the identities of its ß and γ subunits and their function in olfactory signal transduction, however, have not been well established yet. We, and others, have found the expression of Gγ13 in the olfactory epithelium, particularly in the cilia of the OSNs. In this study, we generated a conditional gene knock-out mouse line to specifically nullify Gγ13 expression in the olfactory marker protein-expressing OSNs. Immunohistochemical and Western blot results showed that Gγ13 subunit was indeed eliminated in the mutant mice's olfactory epithelium. Intriguingly, Gαolf, ß1 subunits, Ric-8B and CEP290 proteins, were also absent in the epithelium whereas the presence of the effector enzyme adenylyl cyclase III remained largely unaltered. Electro-olfactogram studies showed that the mutant animals had greatly reduced responses to a battery of odorants including three presumable pheromones. Behavioral tests indicated that the mutant mice had a remarkably reduced ability to perform an odor-guided search task although their motivation and agility seemed normal. Our results indicate that Gαolf exclusively forms a functional heterotrimeric G-protein with Gß1 and Gγ13 in OSNs, mediating olfactory signal transduction. The identification of the olfactory G-protein's ßγ moiety has provided a novel approach to understanding the feedback regulation of olfactory signal transduction pathways as well as the control of subcellular structures of OSNs.

Lgr5-EGFP marks taste bud stem/progenitor cells in posterior tongue.

Until recently, reliable markers for adult stem cells have been lacking for many regenerative mammalian tissues. Lgr5 (leucine-rich repeat-containing G-protein-coupled receptor 5) has been identified as a marker for adult stem cells in intestine, stomach, and hair follicle; Lgr5-expressing cells give rise to all types of cells in these tissues. Taste epithelium also regenerates constantly, yet the identity of adult taste stem cells remains elusive. In this study, we found that Lgr5 is strongly expressed in cells at the bottom of trench areas at the base of circumvallate (CV) and foliate taste papillae and weakly expressed in the basal area of taste buds and that Lgr5-expressing cells in posterior tongue are a subset of K14-positive epithelial cells. Lineage-tracing experiments using an inducible Cre knockin allele in combination with Rosa26-LacZ and Rosa26-tdTomato reporter strains showed that Lgr5-expressing cells gave rise to taste cells, perigemmal cells, along with self-renewing cells at the bottom of trench areas at the base of CV and foliate papillae. Moreover, using subtype-specific taste markers, we found that Lgr5-expressing cell progeny include all three major types of adult taste cells. Our results indicate that Lgr5 may mark adult taste stem or progenitor cells in the posterior portion of the tongue.

Transrepression activity of T-box1 in a gene regulation network in mouse cells.

T-box1 (TBX1) has been identified as a candidate disease-causing gene in DiGeorge syndrome/conotruncal anomaly face syndrome (DGS/CAFS). Tbx1 can function as a transcriptional transactivator as well as a transrepressor. Although the transactivating role of Tbx1 has been the focus of a number of published studies, its transrepression activity has been largely unexplored. Thus, this study centers on the identification of potential transrepressed targets of Tbx1. By subtractive hybridization, we compared the expression profiles of control mouse P19 cells and P19 cells depleted of Tbx1 via RNA interference. We identified 127 genes that were potentially transrepressed by Tbx1. Of the transrepressed genes, we focused on Ywhae and C1qbp and carried out promoter assays. The results showed that Tbx1 potentially transrepresses the promoter activities of these genes via palindromic sequences, including 5'-CCACAG-3' and 5'-(C/G)TGTG(C/G)-3', harbored within the promoters. Electromobility shift assays also showed that Tbx1 specifically interacts with certain portions of these promoter sequences. Moreover, the construction of Tbx1 mutants containing known human TBX1 mutations showed that these mutations result in the loss of Tbx1 transrepression activity. These results indicate that Tbx1 functions as a transrepressor in a gene regulation network, wherein Ywhae and C1qbp are 2 of the targets transrepressed by Tbx1 via T-box binding elements. Hence, the loss of TBX1 transrepression activity could be associated with the disease phenotypes of patients with DGS/CAFS.

Quantitative distribution of mRNAs encoding the 19 human UDP-glucuronosyltransferase enzymes in 26 adult and 3 fetal tissues.

The purpose of this study was to generate, by real-time PCR, a quantitative expression level profile of the 19 human UDP-glucuronosyltransferases (UGTs) of subfamilies 1A, 2A and 2B, in 26 adult and 3 fetal tissues, for better understanding of their roles in xenobiotic and endobiotic metabolism. Adult liver contained the highest level of combined UGTs mRNA, and UGT2B4 was the most abundant isoform in this tissue (40% of total). Other well expressed hepatic UGTs, in decreasing order of mRNA level, were 1A9, 2B7, 1A4, 2B10, 1A1, 1A6, 2B11, 2B15, 1A3, 2A3, 2B17 and 2B28. UGT2B4 was by far the most abundant isoform in the fetal liver (90% of total). The combined UGT mRNA expression in both adult and fetal olfactory epithelium was high, about 20% the adult hepatic level. Interestingly, a large developmental change was found in this tissue from high UGT2A1 and UGT2A2 expression in the fetus to UGT1A6 in the adult. The most abundantly expressed UGTs in the small intestine were 2A3, 1A10, 1A1, 1A6 and 2B7, while 1A10 and 2A3 predominated in the colon. The results provide the most comprehensive data to date on the tissue distribution of the human UGTs.

Glucose transporters and ATP-gated K+ (KATP) metabolic sensors are present in type 1 taste receptor 3 (T1r3)-expressing taste cells.

Although the heteromeric combination of type 1 taste receptors 2 and 3 (T1r2 + T1r3) is well established as the major receptor for sugars and noncaloric sweeteners, there is also evidence of T1r-independent sweet taste in mice, particularly so for sugars. Before the molecular cloning of the T1rs, it had been proposed that sweet taste detection depended on (a) activation of sugar-gated cation channels and/or (b) sugar binding to G protein-coupled receptors to initiate second-messenger cascades. By either mechanism, sugars would elicit depolarization of sweet-responsive taste cells, which would transmit their signal to gustatory afferents. We examined the nature of T1r-independent sweet taste; our starting point was to determine if taste cells express glucose transporters (GLUTs) and metabolic sensors that serve as sugar sensors in other tissues. Using RT-PCR, quantitative PCR, in situ hybridization, and immunohistochemistry, we determined that several GLUTs (GLUT2, GLUT4, GLUT8, and GLUT9), a sodium-glucose cotransporter (SGLT1), and two components of the ATP-gated K(+) (K(ATP)) metabolic sensor [sulfonylurea receptor (SUR) 1 and potassium inwardly rectifying channel (Kir) 6.1] were expressed selectively in taste cells. Consistent with a role in sweet taste, GLUT4, SGLT1, and SUR1 were expressed preferentially in T1r3-positive taste cells. Electrophysiological recording determined that nearly 20% of the total outward current of mouse fungiform taste cells was composed of K(ATP) channels. Because the overwhelming majority of T1r3-expressing taste cells also express SUR1, and vice versa, it is likely that K(ATP) channels constitute a major portion of K(+) channels in the T1r3 subset of taste cells. Taste cell-expressed glucose sensors and K(ATP) may serve as mediators of the T1r-independent sweet taste of sugars.

Neuropathology of the olfactory mucosa in chronic rhinosinusitis.

BACKGROUND: Chronic rhinosinusitis (CRS) is a complex heterogeneous inflammatory disease that affects the nasal cavity, but the pathological examination of the olfactory mucosa (OM) in this disease has been limited. METHODS: Nasal biopsy specimens were obtained from 20 control subjects and 50 CRS patients in conjunction with clinical assessments. Histopathology of these nasal biopsy specimens was performed and immunohistochemistry was used to characterize nonneuronal, neuronal, and inflammatory cells in the OM. These OM characteristics were then evaluated to determine the degree to which pathological features may be related to smell loss in CRS. RESULTS: Histopathological examination of control and CRS OM revealed changes in the normal pseudostratified olfactory epithelium (OE): intermixing of goblet cells, metaplasia to squamous-like cells, and erosion of the OE. Lower percentages of normal epithelium and olfactory sensory neurons were found in CRS OE compared with controls. Relative to other CRS patients, those with anosmia had the greatest amount of OE erosion, the highest density of eosinophils infiltrating the OE, and exhibited the most extensive abnormalities on CT and endoscopic examination, including being significantly more likely to exhibit nasal polyposis. CONCLUSION: Our results suggest that OM pathology observed in nasal biopsy specimens can assist in understanding the degree of epithelial change and sensorineural damage in CRS and the potential for olfactory loss.

Human UDP-glucuronosyltransferase UGT2A2: cDNA construction, expression, and functional characterization in comparison with UGT2A1 and UGT2A3.

OBJECTIVES: Characterize the expression and glucuronidation activities of the human uridine 5'-diphospho (UDP)-glucuronosyltransferase (UGT) 2A2. METHOD: UGT2A1 was cloned from nasal mucosa mRNA. Synthetic cDNA for UGT2A2 was constructed assuming exon sharing between UGT2A1 and UGT2A2 (Mackenzie et al., Pharmacogenetics and Genomics 2005, 15:677-685). Exon 1 of UGT2A2 was amplified from genomic DNA and combined with exons 2-6 of UGT2A1. UGT2A3 was cloned from liver mRNA. Quantitative reverse-transcribed-PCR (RT-PCR) was used to evaluate the expression of all the three UGTs of subfamily 2A in different tissues. Recombinant UGT2A1, UGT2A2 and UGT2A3 were expressed in baculovirus-infected insect cells and analyzed for glucuronidation activity towards different substrates. RESULTS: DNA sequencing of RT-PCR products from human nasal mucosa mRNA, confirmed exon sharing between UGT2A1 and UGT2A2. In addition, it indicated that the N-terminal signal peptide sequence of UGT2A2 is the longest among the human UGTs. Quantitative RT-PCR revealed that both UGT2A1 and UGT2A2 are mainly expressed in the nasal mucosa, and that their expression level in fetal samples was much higher than in adults. Activity assays with recombinant UGTs 2A1-2A3 showed broad substrate selectivity for UGT2A1 and UGT2A2. Although glucuronidation rates and substrate affinities were mostly higher in UGT2A1, the Km values for UDP-glucuronic acid were similar in both UGTs. In addition, there were regioselectivity differences between the two UGTs and, with a few substrates, particularly ethinylestradiol, the activity of UGT2A2 was higher. CONCLUSION: UGT2A2 is mainly expressed in the nasal mucosa and it has glucuronidation activity towards several different endobiotic and xenobiotic substrates.

Analysis of the olfactory mucosa in chronic rhinosinusitis.

The impact of chronic rhinosinusitis (CRS) on the olfactory mucosa (OM) is dramatic. Cellular profiles and epithelial integrity in OM biopsies were evaluated using histological and immunohistochemical methods to define a strategy for future histological studies of CRS. We have examined nasal biopsies of 54 CRS patients (18-63 years old) and have defined specific histopathological patterns of the OM: normal pseudostratified, goblet cell hyperplasia, squamous metaplasia, and erosion. Goblet cell hyperplasia was most similar to a normal pseudostratified OM pattern but with goblet cells intermixed in the apical layers. Squamous metaplasia exhibited an absence of olfactory supporting cells and had olfactory sensory neurons that were morphologically abnormal. It is unknown if these neurons would be functional in this type of tissue transformation. The pattern of erosion exhibited a severe loss of epithelial layers and a higher prevalence of infiltrating inflammatory cells within the olfactory epithelium when compared to the other OM patterns. Although it is not known if the OM patterns we have noted correspond to specific stages or distinct pathways of the disease, the template proposed here can be used in further studies to understand how the histopathological progression of CRS relates to olfactory loss and the response to treatment.

Assessment of smoking status based on cotinine levels in nasal lavage fluid.

Cotinine is a principal metabolite of nicotine with a substantially longer half-life, and cotinine levels in saliva, urine or serum are widely used to validate self-reported smoking status. The nasal cavity and olfactory system are directly exposed to tobacco smoke in smokers and in non-smokers who live with or work around smokers. However, despite the potential for a direct impact of tobacco smoke on the nasal epithelium and olfactory neurons, no prior studies have assessed cotinine levels in nasal mucus. We sought to determine whether cotinine levels in nasal lavage fluid (NLF) would provide a reasonable estimate of smoke exposure. We assayed cotinine using a competitive immunoassay in NLF from 23 smokers, 10 non-smokers exposed to tobacco smoke (ETS) and 60 non-smokers who did not report smoke exposure. NLF cotinine levels were significantly higher in smokers than in non-smokers, regardless of their exposure to ambient tobacco smoke. Cotinine levels in this small group of exposed non-smokers were not significantly different than those of non-exposed non-smokers. A cutoff of 1 ng/ml provided a sensitivity of 91% and a specificity of 99% for smoking status in this sample. Data were consistent with self-reported smoking status, and a cutoff of 1.0 ng/ml NLF cotinine may be used to classify smoking status. While saliva is the most easily obtained body fluid, NLF can be used to provide an objective and precise indication of smoking status and more directly reflects smoke exposure in the nasal and olfactory mucosa.

Smoking-associated squamous metaplasia in olfactory mucosa of patients with chronic rhinosinusitis.

Few studies have examined the induction of squamous metaplasia in human olfactory nasal tissue caused by tobacco use and the implications it may have for olfaction, particularly when there are pre-existing insults, such as chronic rhinosinusitis (CRS). Quantitative histopathological analyses were performed on Alcian blue- and H&E-stained sections of nasal biopsies taken from the upper aspect of the middle turbinate of CRS patients. Chronic rhinosinusitis patients who were current smokers had a predominance of squamous metaplasia in the olfactory sensory epithelium, whereas CRS patients who were nonsmokers and were not exposed to secondhand cigarette smoke had a prevalence of goblet cell hyperplasia. In spite of this difference, the groups did not differ significantly in olfactory threshold sensitivity. The impact of primary cigarette smoke on olfaction and a possible role of squamous metaplasia in preserving olfactory neurogenesis are discussed.

Immune cells of the human peripheral taste system: dominant dendritic cells and CD4 T cells.

Taste loss or alterations can seriously impact health and quality of life due to the resulting negative influence on eating habits and nutrition. Infection and inflammation are thought to be some of the most common causes of taste perception disorders. Supporting this view, neuro-immune interactions in the peripheral gustatory system have been identified, underlying the importance of this tissue in mucosal immunity, but we have little understanding of how these interactions influence taste perception directly or indirectly. This limited understanding is evident by the lack of even a basic knowledge of the resident immune cell populations in or near taste tissues. The present study characterized the distribution and population of the major immune cells and their subsets in healthy human anterior, lingual, fungiform papillae (FP) using immunohistochemistry. Dendritic cells (DCs) were the predominant innate immune cells in this tissue, including four subtypes: CD11c(+) DCs, DC-SIGN+ immature DCs, CD83(+) mature DCs, and CD1a(+) DCs (Langerhans cells). While most DCs were localized beneath the lamina propria and only moderately in the epithelium, CD1a(+) Langerhans cells were exclusively present within the epithelium and not in sub-strata. A small number of macrophages were observed. T lymphocytes were present throughout the FP with CD4(+) T cells more prevalent than CD8(+) T cells. Very few CD19(+) B lymphocytes were detected. The results show that DCs, macrophages, and T lymphocytes are the constitutive guardians of human FP taste tissue, with DCs and CD4 T cells being dominant, while B lymphocytes are rare under normal, healthy conditions. These observations provide a basic anatomical foundation for the immune response in the healthy human tongue as a basis for subsequent disease-related studies, but none of the present data indicate that the immune cell populations identified are, in fact, altered in individuals with abnormal taste perception.