Comparative ultrastructure of the olfactory system in the East African root rat (Tachyoryctes splendens) and the naked mole rat (Heterocephalus glaber)

The ultrastructure of the olfactory system of most fossorial rodents remains largely unexplored. This study sought to investigate the functional structure of the olfactory mucosa and olfactory bulb of two species of fossorial rodents that have distinct behaviour and ecology, the East African root rat (RR) and the naked mole rat (NMR). Transmission electron microscopy and scanning electron microscopy were employed. The basic ultrastructural design of the olfactory system of the two species was largely comparable. In both species, the olfactory mucosa comprised an olfactory epithelium and an underlying lamina propria. The olfactory epithelium revealed olfactory knobs, cilia and microvilli apically and sustentancular cells, olfactory receptor neurons and basal cells in the upper, middle and basal zones, respectively. The lamina propria was constituted by Bowman's glands, olfactory nerve bundles and vasculature supported by loose connective tissue. Within the olfactory bulb, intracellular and extracellular structures including cell organelles, axons and dendrites were elucidated. Notable species differences were observed in the basal zone of the olfactory epithelium and on the luminal surface of the olfactory mucosa. The basal zone of the olfactory epithelium of the RR consisted of a single layer of flattened electron-dense horizontal basal cells while the NMR had juxtaposed electron-dense and electron-lucent heterogenous cells, an occurrence seen as being indicative of quiescent and highly proliferative states of the olfactory epithelia in the two species, respectively. The olfactory epithelial surface of the NMR comprised an elaborate cilia network that intertwined extensively forming loop-like structures whereas in the RR, the surface was rugged and consisted of finger-like processes and irregular masses. With gross and histological studies showing significant differences in the olfactory structures of the two species, these findings are a further manifestation that the olfactory system of the RR and the NMR have evolved differently to reflect their varied olfactory functional needs.

Detection of TDP-43 seeding activity in the olfactory mucosa from patients with frontotemporal dementia

INTRODUCTION

We assessed TAR DNA-binding protein 43 (TDP-43) seeding activity and aggregates detection in olfactory mucosa of patients with frontotemporal lobar degeneration with TDP-43-immunoreactive pathology (FTLD-TDP) by TDP-43 seeding amplification assay (TDP43-SAA) and immunocytochemical analysis.

METHODS

The TDP43-SAA was optimized using frontal cortex samples from 16 post mortem cases with FTLD-TDP, FTLD with tau inclusions, and controls. Subsequently, olfactory mucosa samples were collected from 17 patients with FTLD-TDP, 15 healthy controls, and three patients carrying MAPT variants.

RESULTS

TDP43-SAA discriminated with 100% accuracy post mortem cases presenting or lacking TDP-43 neuropathology. TDP-43 seeding activity was detectable in the olfactory mucosa, and 82.4% of patients with FTLD-TDP tested positive, whereas 86.7% of controls tested negative (P < 0.001). Two out of three patients with MAPT mutations tested negative. In TDP43-SAA positive samples, cytoplasmatic deposits of phosphorylated TDP-43 in the olfactory neural cells were detected.

DISCUSSION

TDP-43 aggregates can be detectable in olfactory mucosa, suggesting that TDP43-SAA might be useful for identifying and monitoring FTLD-TDP in living patients.

Single-dose intranasal administration of α-syn PFFs induce lewy neurite-like pathology in olfactory bulbs

INTRODUCTION

Pathological α-synuclein (α-Syn) propagation may cause Parkinson's disease progression. We aimed to verify whether single-dose intranasal administration of α-Syn preformed fibrils (PFFs) induces α-Syn pathology in the olfactory bulb (OB).

METHODS

A single dose of α-Syn PFFs was administered to the left nasal cavity of wild-type mice. The untreated right side served as a control. The α-Syn pathology of the OBs was examined up to 12 months after the injection.

RESULTS

Lewy neurite-like aggregates were observed in the OB 6 and 12 months after the treatment.

CONCLUSIONS

These findings suggest that pathological α-Syn can propagate from the olfactory mucosa to the OB and reveal the potential dangers of α-Syn PFFs inhalation.

High prevalence of olfactory dysfunction detected in treatment-naive patients with head and neck cancer

BACKGROUND

Previous studies demonstrated the difficulty of patients with Head and Neck Cancer (HNC) in sensing food taste, a function in which olfaction has a significant role. However, neither study employed psychophysical tests or control groups to establish the veracity of such complaints.

AIMS/OBJECTIVES

In this study, we quantitatively tested the olfactory function of HNC individuals and compared their function to that of healthy controls.

METHODS

Thirty-one HNC naïve treatment patients and thirty-one controls, matched for sex, age, schooling, and smoking, were tested with the University of Pennsylvania Smell Identification Test (UPSIT).

RESULTS

The olfactory function was significantly worse among the patients diagnosed with head and neck cancer [UPSIT cancer = 22.9(CI 95%: 20.5-25.4) vs. UPSIT controls = 29.1(CI 95%: 26.9-31.3); p < .001]. Most patients with HNC had olfactory disorders (n = 29, 93.5%). The risk of olfactory loss was higher in the cancer group [OR: 10.5(CI 95%: 2.1-51.9; p = .001)].

CONCLUSION AND SIGNIFICANCE

Olfactory disorders can be detected in more than 90% of patients with head and neck cancer when evaluated using a well-validated olfactory test. Smell disorders may be a potential marker for early diagnosis of HNC.

Corrigendum: PMCA-based detection of prions in the olfactory mucosa of patients with sporadic Creutzfeldt-Jakob disease

[This corrects the article DOI: 10.3389/fnagi.2022.848991.].

Ablation of AQP5 gene in mice leads to olfactory dysfunction caused by hyposecretion of Bowman's gland

Smell detection depends on nasal airflow, which can make absorption of odors to the olfactory epithelium by diffusion through the mucus layer. The odors then act on the chemo-sensitive epithelium of olfactory sensory neurons (OSNs). Therefore, any pathological changes in the olfactory area, for instance, dry nose caused by Sjögren's Syndrome (SS) may interfere with olfactory function. SS is an autoimmune disease in which aquaporin (AQP) 5 autoantibodies have been detected in the serum. However, the expression of AQP5 in olfactory mucosa and its function in olfaction is still unknown. Based on the study of the expression characteristics of AQP5 protein in the nasal mucosa, the olfaction dysfunction in AQP5 knockout (KO) mice was found by olfactory behavior analysis, which was accompanied by reduced secretion volume of Bowman's gland by using in vitro secretion measure system, and the change of acid mucin in nasal mucus layer was identified. By excluding the possibility that olfactory disturbance was caused by changes in OSNs, the result indicated that AQP5 contributes to olfactory functions by regulating the volume and composition of OE mucus layer, which is the medium for the dissolution of odor molecules. Our results indicate that AQP5 can affect the olfactory functions by regulating the water supply of BGs and the mucus layer upper the OE that can explain the olfactory loss in the patients of SS, and AQP5 KO mice might be used as an ideal model to study the olfactory dysfunction.

Approaching the Gut and Nasal Microbiota in Parkinson's Disease in the Era of the Seed Amplification Assays

Parkinson's disease (PD) is a neurodegenerative disorder often associated with pre-motor symptoms involving both gastrointestinal and olfactory tissues. PD patients frequently suffer from hyposmia, hyposalivation, dysphagia and gastrointestinal dysfunctions. During the last few years it has been speculated that microbial agents could play a crucial role in PD. In particular, alterations of the microbiota composition (dysbiosis) might contribute to the formation of misfolded α-synuclein, which is believed to be the leading cause of PD. However, while several findings confirmed that there might be an important link between intestinal microbiota alterations and PD onset, little is known about the potential contribution of the nasal microbiota. Here, we describe the latest findings on this topic by considering that more than 80% of patients with PD develop remarkable olfactory deficits in their prodromal disease stage. Therefore, the nasal microbiota might contribute to PD, eventually boosting the gut microbiota in promoting disease onset. Finally, we present the applications of the seed amplification assays to the study of the gut and olfactory mucosa of PD patients, and how they could be exploited to investigate whether pathogenic bacteria present in the gut and the nose might promote α-synuclein misfolding and aggregation.

Human nasal olfactory stem cells, purified as advanced therapy medicinal products, improve neuronal differentiation

BACKGROUND

Olfactory ecto-mesenchymal stem cells (OE-MSC) are mesenchymal stem cells derived from the lamina propria of the nasal mucosa. They display neurogenic and immunomodulatory properties and were shown to induce recovery in animal models of spinal cord trauma, hearing loss, Parkinsons's disease, amnesia, and peripheral nerve injury. As a step toward clinical practice, we sought to (i) devise a culture protocol that meets the requirements set by human health agencies and (ii) assess the efficacy of stem cells on neuron differentiation.

METHODS

Nasal olfactory mucosa biopsies from three donors were used to design and validate the good manufacturing process for purifying stem cells. All processes and procedures were performed by expert staff from the cell therapy laboratory of the public hospital of Marseille (AP-HM), according to aseptic handling manipulations. Premises, materials and air were kept clean at all times to avoid cross-contamination, accidents, or even fatalities. Purified stem cells were cultivated for 24 or 48 h and conditioned media were collected before being added to the culture medium of the neuroblastoma cell line Neuro2a.

RESULTS

Compared to the explant culture-based protocol, enzymatic digestion provides higher cell numbers more rapidly and is less prone to contamination. The use of platelet lysate in place of fetal calf serum is effective in promoting higher cell proliferation (the percentage of CFU-F progenitors is 15.5%), with the optimal percentage of platelet lysate being 10%. Cultured OE-MSCs do not show chromosomal rearrangement and, as expected, express the usual phenotypic markers of mesenchymal stem cells. When incorporated in standard culture medium, the conditioned medium of purified OE-MSCs promotes cell differentiation of Neuro2a neuroblastoma cells.

CONCLUSION

We developed a safer and more efficient manufacturing process for clinical grade olfactory stem cells. With this protocol, human OE-MSCs will soon be used in a Phase I clinical based on their autologous transplantation in digital nerves with a neglected injury. However, further studies are required to unveil the underlying mechanisms of action.

Lectin histochemistry of the olfactory mucosa of Korean native cattle, Bos taurus coreanae

BACKGROUND

The olfactory mucosa (OM) is crucial for odorant perception in the main olfactory system. The terminal carbohydrates of glycoconjugates influence chemoreception in the olfactory epithelium (OE).

OBJECTIVES

The histological characteristics and glycoconjugate composition of the OM of Korean native cattle (Hanwoo, Bos taurus coreae) were examined to characterize their morphology and possible functions during postnatal development.

METHODS

The OM of neonate and adult Korean native cattle was evaluated using histological, immunohistochemical, and lectin histochemical methods.

RESULTS

Histologically, the OM in both neonates and adults consists of the olfactory epithelium and the lamina propria. Additionally, using periodic acid Schiff and Alcian blue (pH 2.5), the mucus specificity of the Bowman's gland duct and acini in the lamina propria was determined. Immunohistochemistry demonstrated that mature and immature olfactory sensory neurons of OEs express the olfactory marker protein and growth associated protein-43, respectively. Lectin histochemistry indicated that numerous glycoconjugates, including as N-acetylglucosamine, mannose, galactose, N-acetylgalactosamine, complex type N-glycan, and fucose groups, were expressed at varied levels in the different cell types in the OMs of neonates and adults at varying levels. According to our observations, the cattle possessed a well-developed olfactory system, and the expression patterns of glycoconjugates in neonatal and adult OMs varied considerably.

CONCLUSIONS

This is the first study to describe the morphological assessment of the OM of Korean native cattle with a focus on lectin histochemistry. The findings suggest that glycoconjugates may play a role in olfactory chemoreception, and that their labeling properties may be closely related to OM development and maturity.

Dietary n-3 polyunsaturated fatty acid deficiency alters olfactory mucosa sensitivity in young mice but has no impact on olfactory behavior

BACKGROUND AND OBJECTIVE

We recently showed that perinatal exposure to diets with unbalanced n-6:n-3 polyunsaturated fatty acid (PUFA) ratios affects the olfactory mucosa (OM) fatty acid composition. To assess the repercussions of these modifications, we investigated the impact of diets unbalanced in n-3 PUFAs on the molecular composition and functionality of the OM in young mice.

METHODS

After mating, female mice were fed diets either deficient in α-linolenic acid (LOW diet) or supplemented with n-3 long-chain PUFAs (HIGH diet) during the perinatal period. Weaned male offspring were then fed ad libitum with the same experimental diets for 5 weeks. At 8 weeks of age, olfactory behavior tests were performed in young mice. The fatty acid composition of OM and olfactory cilia, as well as the expression of genes involved in different cellular pathways, were analyzed. The electroolfactograms induced by odorant stimuli were recorded to assess the impact of diets on OM functionality.

RESULTS AND CONCLUSION

Both diets significantly modified the fatty acid profiles of OM and olfactory cilia in young mice. They also induced changes in the expression of genes involved in olfactory signaling and in olfactory neuron maturation. The electroolfactogram amplitudes were reduced in mice fed the LOW diet. Nevertheless, the LOW diet and the HIGH diet did not affect mouse olfactory behavior. Our study demonstrated that consumption of diets deficient in or supplemented with n-3 PUFAs during the perinatal and postweaning periods caused significant changes in young mouse OM. However, these modifications did not impair their olfactory capacities.

A 3D transcriptomics atlas of the mouse nose sheds light on the anatomical logic of smell

The sense of smell helps us navigate the environment, but its molecular architecture and underlying logic remain understudied. The spatial location of odorant receptor genes (Olfrs) in the nose is thought to be independent of the structural diversity of the odorants they detect. Using spatial transcriptomics, we create a genome-wide 3D atlas of the mouse olfactory mucosa (OM). Topographic maps of genes differentially expressed in space reveal that both Olfrs and non-Olfrs are distributed in a continuous and overlapping fashion over at least five broad zones in the OM. The spatial locations of Olfrs correlate with the mucus solubility of the odorants they recognize, providing direct evidence for the chromatographic theory of olfaction. This resource resolves the molecular architecture of the mouse OM and will inform future studies on mechanisms underlying Olfr gene choice, axonal pathfinding, patterning of the nervous system, and basic logic for the peripheral representation of smell.

Direct nose to the brain nanomedicine delivery presents a formidable challenge

This advanced review describes the anatomical and physiological barriers and mechanisms impacting nanomedicine translocation from the nasal cavity directly to the brain. There are significant physiological and anatomical differences in the nasal cavity, olfactory area, and airflow reaching the olfactory epithelium between humans and experimentally studied species that should be considered when extrapolating experimental results to humans. Mucus, transporters, and tight junction proteins present barriers to material translocation across the olfactory epithelium. Uptake of nanoparticles through the olfactory mucosa and translocation to the brain can be intracellular via cranial nerves (intraneuronal) or other cells of the olfactory epithelium, or extracellular along cranial nerve pathways (perineural) and surrounding blood vessels (perivascular, the glymphatic system). Transport rates vary greatly among the nose to brain pathways. Nanomedicine physicochemical properties (size, surface charge, surface coating, and particle stability) can affect uptake efficiency, which is usually less than 5%. Incorporation of therapeutic agents in nanoparticles has been shown to produce pharmacokinetic and pharmacodynamic benefits. Assessment of adverse effects has included olfactory mucosa toxicity, ciliotoxicity, and olfactory bulb and brain neurotoxicity. The results have generally suggested the investigated nanomedicines do not present significant toxicity. Research needs to advance the understanding of nanomedicine translocation and its drug cargo after intranasal administration is presented. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

PMCA-Based Detection of Prions in the Olfactory Mucosa of Patients With Sporadic Creutzfeldt-Jakob Disease

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare neurodegenerative disorder caused by the conformational conversion of the prion protein (PrP^C) into an abnormally folded form, named prion (or PrP^Sc). The combination of the polymorphism at codon 129 of the PrP gene (coding either methionine or valine) with the biochemical feature of the proteinase-K resistant PrP (generating either PrP^Sc type 1 or 2) gives rise to different PrP^Sc strains, which cause variable phenotypes of sCJD. The definitive diagnosis of sCJD and its classification can be achieved only post-mortem after PrP^Sc identification and characterization in the brain. By exploiting the Real-Time Quaking-Induced Conversion (RT-QuIC) assay, traces of PrP^Sc were found in the olfactory mucosa (OM) of sCJD patients, thus demonstrating that PrP^Sc is not confined to the brain. Here, we have optimized another technique, named protein misfolding cyclic amplification (PMCA) for detecting PrP^Sc in OM samples of sCJD patients. OM samples were collected from 27 sCJD and 2 genetic CJD patients (E200K). Samples from 34 patients with other neurodegenerative disorders were included as controls. Brains were collected from 26 sCJD patients and 16 of them underwent OM collection. Brain and OM samples were subjected to PMCA using the brains of transgenic mice expressing human PrP^C with methionine at codon 129 as reaction substrates. The amplified products were analyzed by Western blot after proteinase K digestion. Quantitative PMCA was performed to estimate PrP^Sc concentration in OM. PMCA enabled the detection of prions in OM samples with 79.3% sensitivity and 100% specificity. Except for a few cases, a predominant type 1 PrP^Sc was generated, regardless of the tissues analyzed. Notably, all amplified PrP^Sc were less resistant to PK compared to the original strain. In conclusion, although the optimized PMCA did not consent to recognize sCJD subtypes from the analysis of OM collected from living patients, it enabled us to estimate for the first time the amount of prions accumulating in this biological tissue. Further assay optimizations are needed to faithfully amplify peripheral prions whose recognition could lead to a better diagnosis and selection of patients for future clinical trials.

Gene and protein expression profiles of olfactory ensheathing cells from olfactory bulb versus olfactory mucosa

Olfactory ensheathing cells (OECs) from the olfactory bulb (OB) and the olfactory mucosa (OM) have the capacity to repair nerve injury. However, the difference in the therapeutic effect between OB-derived OECs and OM-derived OECs remains unclear. In this study, we extracted OECs from OB and OM and compared the gene and protein expression profiles of the cells using transcriptomics and non-quantitative proteomics techniques. The results revealed that both OB-derived OECs and OM-derived OECs highly expressed genes and proteins that regulate cell growth, proliferation, apoptosis and vascular endothelial cell regeneration. The differentially expressed genes and proteins of OB-derived OECs play a key role in regulation of nerve regeneration and axon regeneration and extension, transmission of nerve impulses and response to axon injury. The differentially expressed genes and proteins of OM-derived OECs mainly participate in the positive regulation of inflammatory response, defense response, cytokine binding, cell migration and wound healing. These findings suggest that differentially expressed genes and proteins may explain why OB-derived OECs and OM-derived OECs exhibit different therapeutic roles. This study was approved by the Animal Ethics Committee of the General Hospital of Ningxia Medical University (approval No. 2017-073) on February 13, 2017.

Investigation of the Transport Pathways Associated with Enhanced Brain Delivery of Peptide Drugs by Intranasal Coadministration with Penetratin

We previously found that coadministering peptides and proteins with the cell-penetrating peptide L-penetratin intranasally significantly increased transport to the brain and enhanced pharmacological effects. The present study aimed to clarify the mechanisms of nose-to-brain drug delivery enhancement by L-penetratin coadministration. First, we compared the concentrations of Exendin-4 in plasma and brain after intranasal and subcutaneous administration and suggested that coadministration with L-penetratin facilitated the direct nose-to-brain transport of Exendin-4. Second, we demonstrated that L-penetratin did not stimulate the transport of Cy7-labeled Exendin-4 and insulin through the trigeminal nerves but shifted their distribution to the olfactory mucosal pathway. Third, we investigated the distribution of insulin into the deeper regions of the brain after delivery via the olfactory pathway and suggested that insulin had entered the olfactory bulb, bottom part of the brain, and perivascular space through the cerebrospinal fluid and had diffused throughout the brain. We further demonstrated that intranasally delivered insulin with L-penetratin specifically accumulated on the hippocampus neuronal cells. Thus, this study suggested that administrating peptide drugs intranasally with L-penetratin allows direct transport to the olfactory bulb, bottom part of the brain, and perivascular space of the cerebral artery. This technique also potentially allows targeting of specific brain areas.

Squamous and Respiratory Metaplasia After Olfactory Mucosal Resection

Resection of the olfactory mucosa (OM) is sometimes unavoidable during surgery; however, it is not known whether the OM can completely recover thereafter. The aim of this study was to uncover whether the OM fully recovers after mucosal resection and describe the process of OM regeneration. 8-week-old male Sprague–Dawley rats (n = 18) were subjected to OM resection at the nasal septum; six rats were euthanized for histological examination 0, 30, and 90 days after surgery. Immunohistochemistry was performed to identify olfactory receptor neuron (ORN) lineage cells [mature and immature ORNs and ORN progenitors, and olfactory ensheathing cells (OECs)], as well as dividing and apoptotic cells. Squamous and respiratory metaplasia and inflammatory cell infiltration were also assessed. On day 30 after resection, the mucosa had regenerated, and mainly contained thin nerve bundles, basal cells, and immature ORNs, with a few mature ORNs and OECs. On day 90, the repaired nasal mucosa had degenerated into stratified squamous or ciliated pseudostratified columnar epithelia, with reducing ORNs. The lamina propria contained numerous macrophages. Partial regeneration was observed within 1 month after OM resection, whereas subsequent degeneration into squamous and respiratory epithelia occurred within 3 months. Given the poor persistence of ORNs and OECs, OM resection is likely to result in olfactory impairment. Overall, surgeons should be cautious not to injure the OM during surgery.

PMCA-generated prions from the olfactory mucosa of patients with Fatal Familial Insomnia cause prion disease in mice

Background:

Fatal Familial Insomnia (FFI) is a genetic prion disease caused by the D178N mutation in the prion protein gene (PRNP) in coupling phase with methionine at PRNP 129. In 2017, we have shown that the olfactory mucosa (OM) collected from FFI patients contained traces of PrPSc detectable by Protein Misfolding Cyclic Amplification (PMCA).

Methods:

In this work, we have challenged PMCA-generated products obtained from OM and brain homogenate of FFI patients in BvPrP-Tg407 transgenic mice expressing the bank vole prion protein to test their ability to induce prion pathology.

Results:

All inoculated mice developed mild spongiform changes, astroglial activation, and PrPSc deposition mainly affecting the thalamus. However, their neuropathological alterations were different from those found in the brain of BvPrP-Tg407 mice injected with raw FFI brain homogenate.

Conclusions:

Although with some experimental constraints, we show that PrPSc present in OM of FFI patients is potentially infectious.

Funding:

This work was supported in part by the Italian Ministry of Health (GR-2013-02355724 and Ricerca Corrente), MJFF, ALZ, Alzheimer’s Research UK and the Weston Brain Institute (BAND2015), and Euronanomed III (SPEEDY) to FM; by the Spanish Ministerio de Economía y Competitividad (grant AGL2016-78054-R [AEI/FEDER, UE]) to JMT and JCE; AM-M was supported by a fellowship from the INIA (FPI-SGIT-2015-02).

Ischemic-hypoxic preconditioning enhances the mitochondrial function recovery of transplanted olfactory mucosa mesenchymal stem cells via miR-181a signaling in ischemic stroke

Cerebral ischemia/reperfusion injury causes a series of intricate cascade reactions in brain tissue causing apoptosis and proinflammatory programmed cell death known as pyroptosis of nerve cells. The dysfunction of target organelle mitochondria plays a key role in the process of neuronal apoptosis and pyroptosis. Mesenchymal stem cells (MSCs) have been widely used in the experimental or clinical treatment of various ischemic diseases, but the therapeutic efficacy of MSCs on cerebral ischemia-reperfusion injury need to be improved. We successfully cultured olfactory mucosa MSCs (OM-MSCs) to obtain a better source of seed cells. In this way, the therapeutic potential of OM-MSCs transplantation has been evaluated for ischemic stroke using an optimized culture scheme in vitro. Ischemic-hypoxic preconditioned OM-MSCs (IhOM-MSCs) were used to treat a neuron model of oxygen-glucose deprivation/reperfusion and the middle cerebral artery occlusion in rats. These results demonstrated that IhOM-MSCs mediated the upregulation of the downstream target genes GRP78 and Bcl-2 by miR-181a to protect mitochondrial function and inhibit apoptosis and pyroptosis of neurons in the ischemia/reperfusion injury model. Thus, IhOM-MSCs transplantation may be an effective therapy of ischemic stroke in the future.

Alpha-synuclein seeds in olfactory mucosa and cerebrospinal fluid of patients with dementia with Lewy bodies

In patients with suspected dementia with Lewy bodies, the detection of the disease-associated α-synuclein in easily accessible tissues amenable to be collected using minimally invasive procedures remains a major diagnostic challenge. This approach has the potential to take advantage of modern molecular assays for the diagnosis of α-synucleinopathy and, in turn, to optimize the recruitment and selection of patients in clinical trials, using drugs directed at counteracting α-synuclein aggregation. In this study, we explored the diagnostic accuracy of α-synuclein real-time quaking-induced conversion assay by testing olfactory mucosa and CSF in patients with a clinical diagnosis of probable (n = 32) or prodromal (n = 5) dementia with Lewy bodies or mixed degenerative dementia (dementia with Lewy bodies/Alzheimer's disease) (n = 6). Thirty-eight patients with non-α-synuclein-related neurodegenerative and non-neurodegenerative disorders, including Alzheimer's disease (n = 10), sporadic Creutzfeldt-Jakob disease (n = 10), progressive supranuclear palsy (n = 8), corticobasal syndrome (n = 1), fronto-temporal dementia (n = 3) and other neurological conditions (n = 6) were also included, as controls. All 81 patients underwent olfactory swabbing while CSF was obtained in 48 participants. At the initial blinded screening of olfactory mucosa samples, 38 out of 81 resulted positive while CSF was positive in 19 samples out of 48 analysed. After unblinding of the results, 27 positive olfactory mucosa were assigned to patients with probable dementia with Lewy bodies, five with prodromal dementia with Lewy bodies and three to patients with mixed dementia, as opposed to three out 38 controls. Corresponding results of CSF testing disclosed 10 out 10 positive samples in patients with probable dementia with Lewy bodies and six out of six with mixed dementia, in addition to three out of 32 for controls. The accuracy among results of real-time quaking-induced conversion assays and clinical diagnoses was 86.4% in the case of olfactory mucosa and 93.8% for CSF. For the first time, we showed that α-synuclein real-time quaking-induced conversion assay detects α-synuclein aggregates in olfactory mucosa of patients with dementia with Lewy bodies and with mixed dementia. Additionally, we provided preliminary evidence that the combined testing of olfactory mucosa and CSF raised the concordance with clinical diagnosis potentially to 100%. Our results suggest that nasal swabbing might be considered as a first-line screening procedure in patients with a diagnosis of suspected dementia with Lewy bodies followed by CSF analysis, as a confirmatory test, when the result in the olfactory mucosa is incongruent with the initial clinical diagnosis.

Uptake and Transport of Ultrafine Nanoparticles (Quantum Dots) in the Nasal Mucosa

A wide variety of colloidal delivery systems, including polymeric nanoparticles, metal colloids, liposomes, and microemulsions have been reported to enhance the delivery of therapeutic agents across the nasal mucosa. The mechanisms involved in the uptake of these nanomaterials, especially ultrafine nanomaterials (diameters < 20 nm) through the nasal mucosa are not well understood. Fluorescent quantum dots (QDs) were used to investigate the uptake of ultrafine nanoparticles by bovine respiratory and olfactory mucosal tissues following in vitro exposure, and an inductively coupled plasma optical emission spectroscopy method was developed to quantify the amount of QDs localized within the tissues. QDs do not biodegrade or release their core materials and, as a result, this method allowed for the direct quantification of the nanoparticles themselves, rather than the measurement of a potentially dissociated drug or label. The results demonstrated that carboxylate-modified QDs (COOH-QDs) showed ∼2.5-fold greater accumulation in the epithelial and submucosal regions of olfactory tissues compared to that in respiratory tissues. Endocytic inhibitory studies showed that clathrin-dependent endocytosis, macropinocytosis, and caveolae-dependent endocytic process are all involved in the uptake of COOH-QDs into the respiratory tissues. In olfactory tissues, clathrin-dependent endocytosis is the major endocytic pathway involved in the uptake of COOH-QDs. Additional energy-independent pathways also appeared to allow the transfer of COOH-QDs within the olfactory mucosa. When polyethylene glycol-modified QDs known as PEGylated QDs (PEG-QDs) of similar size, ∼15 nm, were investigated, no nanoparticles were detected in the tissues suggesting that the PEG corona limits the interactions with endocytic and other uptake processes in the nasal epithelium. The capacity for nanoparticle uptake observed in the nasal mucosa, along with the ability of significant numbers of nanoparticles to enter the olfactory tissues using nonenergy-dependent pathways show that the pathways for ultrafine nanoparticle uptake in the nasal tissues have both drug delivery and toxicologic consequences. This places an increased importance on the careful selection of nanoparticle components and drugs intended for intranasal administration.

Preparation of Adhesion Culture of Neural Stem/Progenitor Cells of the Olfactory Mucosa for the Treatment of Spinal Cord Injuries

In this work, an optimal protocol was developed for obtaining adhesion culture of neural stem/progenitor cells (NSPC) of rat olfactory mucosa. During the development of the protocol, the conditions for cell culturing on adhesion substrates fibronectin and laminin in DMEM/F-12 and neurobasal media with the same culture additives were compared. Cell proliferation was maximum during culturing on both substrates in the neurobasal medium. Using the immunofluorescence method, we found that culturing on fibronectin in the neurobasal medium ensured maximum (52.22%) content of nestin-positive cells in comparison with other culturing conditions. The highest percentage of βIII-tubulin-positive cells was detected in cultures growing on fibronectin in the neurobasal medium and in DMEM/F-12 (79.11 and 83.52%, respectively). Culturing in adhesion cultures in the neurobasal medium on fibronectin allowed obtaining cultures enriched with NSPC and neurons differentiating from them in a quantity sufficient for further transplantation. The developed protocol can be recommended for obtaining NPSC from human olfactory mucosa for the treatment of spinal cord injuries.

Comparison of the Efficiency of Transplantation of Rat and Human Olfactory Ensheathing Cells in Posttraumatic Cysts of the Spinal Cord

Olfactory ensheathing cells showed significant effects on the regeneration of the spinal cord in experimental models and in clinical trials. However, the use of these cells in the therapy of posttraumatic cysts of the spinal cord has not been studied. Cultures of human and rat olfactory mucosa were obtained according to the protocols developed by us. Passage 3-4 cultures are most enriched with olfactory ensheathing cells and are preferable for transplantation. We performed transplantation of 750,000 olfactory ensheathing cells into the region of modeled cysts. The therapeutic effect of human cells was more pronounced. The positive dynamics of recovery of motor activity in the hind limbs of rats can reflect regenerative processes in the spinal cord after transplantation of olfactory ensheathing cells into the region of posttraumatic cysts.

Efficiency of Human Olfactory Ensheathing Cell Transplantation into Spinal Cysts to Improve Mobility of the Hind Limbs

The pathological processes developing after spinal cord injuries often lead to formation of cysts. Existing surgical and medical methods are insufficient for treatment of post-traumatic spinal cord cysts. One of the emerging tools is cell therapy. Olfactory ensheathing cells (OECs) are perspective cells for cell therapy. In this study, we demonstrated that human OEC transplantation is effective in experimental spinal cysts. For our experiments, we selected animals only at the intermediate stage of recovery with scores from 8 to 13 according to the Basso, Beattie, and Bresnahan (BBB) scale. Cells were transplanted in different quantities (0.75 and 1.5 million) into the fully formed cysts and in the areas of injury without cysts. Improvement of limb mobility after human OEC transplantation into post-traumatic cysts was shown. In the group of rats with cysts, time-dependent increase in the BBB score was observed in subgroups treated with 0.75 and 1.5 million OECs with no statistically significant time-dependent dynamics of BBB values in the control group. When all three subgroups (control and two OEC doses) were compared, the Kruskal-Wallis test showed the presence of differences between subgroups after 1, 3, and 4 weeks of treatment with evidence of divergence increase. There was no statistically significant difference between the two doses of OEC treatment. The human OECs in the experiments without cysts were not effective. It was also shown that PKH26-labeled human OECs survive throughout the experiment and migrate to nearby areas of the cyst. Therefore, it was found that it is effective to transplant human OECs into fully formed cysts. In the future, autologous OECs can be used to personalize the treatment of patients with spinal cysts.

Differentiation of human olfactory system-derived stem cells into dopaminergic neuron-like cells: A comparison between olfactory bulb and mucosa as two sources of stem cells

Cell transplantation has become a possible therapeutic approach in the treatment of neurodegenerative diseases of the nervous system by replacing lost cells. The current study aimed to make a comparison between the differentiation capacity of the olfactory bulb neural stem cells (OB-NSCs) and olfactory ectomesenchymal stem cells (OE-MSCs) into dopaminergic-like neurons under the inductive effect of transforming growth factor β (TGF-β). After culturing and treating with TGF-β, the differentiation capacities of both types of stem cells into dopaminergic neuron-like cells were evaluated. Quantitative real-time polymerase chain reaction analysis 3 weeks after induction demonstrated that the mRNA expression of the dopaminergic activity markers tyrosine hydroxylase (TH), dopamine transporter (DAT), paired box gene 2 (PAX2), and PAX5 in the neuron-like cells derived from OB-NSCs was significantly higher than those derived from OE-MSCs. These findings were further supported by the immunocytochemistry staining showing that the expression of the tyrosine hydroxylase, DAT, PAX2, and paired like homeodomain 3 seemed to be slightly higher in OB-NSCs compared with OE-MSCs. Despite the lower differentiation capacity of OE-MSCs, other considerations such as a noninvasive and easier harvesting process, faster proliferation attributes, longer life span, autologous transplantability, and also the easier and inexpensive cultural process of the OE-MSCs, cumulatively make these cells the more appropriate alternative in the case of autologous transplantation during the treatment process of neurodegenerative disorders like Parkinson's disease.

Olfactory mucosa stem cells: An available candidate for the treatment of the Parkinson's disease

Olfactory ectomesenchymal stem cells (OE-MSCs) possess the immunosuppressive activity and regeneration capacity and hold a lot of promises for neurodegenerative disorders treatment. This study aimed to determine OE-MSCs which are able to augment and differentiate into functional neurons and regenerate the CNS and also examine whether the implantation of OE-MSCs in the pars compacta of the substantia nigra (SNpc) can improve Parkinson's symptoms in a rat model-induced with 6-hydroxydopamine. We isolated OE-MSCs from lamina propria in olfactory mucosa and characterized them using flow cytometry and immunocytochemistry. The therapeutic potential of OE-MSCs was evaluated by the transplantation of isolated cells using a rat model of acute SN injury as a Parkinson's disease. Significant behavioral improvement in Parkinsonian rats was elicited by the OE-MSCs. The results demonstrate that the expression of PAX2, PAX5, PITX3, dopamine transporter, and tyrosine hydroxylase was increased by OE-MSCs compared to the control group which is analyzed with real-time polymerase chain reaction technique and immunohistochemical staining. In the outcome, the transplantation of 1,1'-dioctadecyl-3,3,3'3'-tetramethyl indocarbocyanine perchlorate labeled OE-MSCs that were fully differentiated to dopaminergic neurons contribute to a substantial improvement in patients with Parkinson's. Together, our results provide that using OE-MSCs in neurodegenerative disorders might lead to better neural regeneration.

Possible ATP trafficking by ATP-shuttles in the olfactory cilia and glucose transfer across the olfactory mucosa

Odor transduction in the cilia of olfactory sensory neurons involves several ATP-requiring enzymes. ATP is generated by glycolysis in the ciliary lumen, using glucose incorporated from surrounding mucus, and by oxidative phosphorylation in the dendrite. During prolonged stimulation, the cilia maintain ATP levels along their length, by unknown means. We used immunochemistry, RT-PCR, and immunoblotting to explore possible underlying mechanisms. We found the ATP-shuttles, adenylate and creatine kinases, capable of equilibrating ATP. We also investigated how glucose delivered by blood vessels in the olfactory mucosa reaches the mucus. We detected, in sustentacular and Bowman's gland cells, the crucial enzyme in glucose secretion glucose-6-phosphatase, implicating both cell types as putative glucose pathways. We propose a model accounting for both processes.

Influence of a medialized middle turbinate on olfactory function: a prospective randomized double-blind study

BACKGROUND

Medialization of the middle turbinate (MT) is an effective technique to prevent recurrent rhinosinusitis but could, in theory, reduce olfactory function by interfering the odorants to reach the olfactory mucosae. We performed a prospective randomized double-blind trial under the hypothesis that olfactory functions would be affected by the status of olfactory mucosae, not by MT medialization.

METHODS

In randomly selected sides, the unilateral MT was medialized in 80 patients undergoing bilateral endoscopic sinus surgery for chronic rhinosinusitis. The status of the bilateral olfactory cleft (OC) was photodocumented intraoperatively and categorized into patent (normal or mucosal swelling with discharge) and congested (hypertrophied mucosae or nasal polyps) groups. The butanol threshold test (BTT) was conducted in each nostril before and 6 months after the surgery. Correlation between the BTT scores and MT medialization or the OC status was assessed. No smell identification test was conducted side by side, which might limit clinical implications.

RESULTS

In total, 46 of 80 patients completed the trial. MT medialization was performed on the left and right side of the nose in 19 and 27 cases, respectively. The intraoperative OC status did not differ between the 2 sides. Perioperative changes in the BTT scores were similar between the medialized and intact MT sides, whereas the preoperative and postoperative BTT scores were higher in the patent OC group than in the congested OC group, regardless of side.

CONCLUSION

MT medialization does not impair olfactory function, and OC status is closely related to olfactory function.

Is Olfactory Epithelium Biopsy Useful for Confirming Alzheimer's Disease?

OBJECTIVES

The clinical symptoms of Alzheimer's disease (AD) are preceded by a long asymptomatic period associated with "silent" deposition of aberrant paired helical filament (PHF)-tau and amyloid-beta proteins in brain tissue. Similar depositions have been reported within the olfactory epithelium (OE), a tissue that can be biopsied in vivo. The degree to which such biopsies are useful in identifying AD is controversial. This postmortem study had 3 main goals: first, to quantify the relative densities of AD-related proteins in 3 regions of the olfactory neuroepithelium, namely, the nasal septum, middle turbinate, and superior turbinate; second, to establish whether such densities are correlated among these epithelial regions as well as with semi-quantitative ratings of general brain cortex pathology; and third, to evaluate correlations between the protein densities and measures of antemortem cognitive function.

METHODS

Postmortem blocks of olfactory mucosa were obtained from 12 AD cadavers and 24 controls and subjected to amyloid-beta and PHF-tau immunohistochemistry.

RESULTS

We observed marked heterogeneity in the presence of the biomarkers of tau and amyloid-beta among the targeted olfactory epithelial regions. No significant difference was observed between the cadavers with AD and the controls regarding the concentration of these proteins in any of these epithelial regions. Only one correlation significant was evident, namely, that between the tau protein densities of the middle and the upper turbinate (r = .58, P = .002).

CONCLUSION

AD-related biomarker heterogeneity, which has not been previously demonstrated, makes comparisons across studies difficult and throws into question the usefulness of OE amyloid-beta and PHF-tau biopsies in detecting AD.

Survival and Migration of Rat Olfactory Ensheathing Cells after Transplantation into Posttraumatic Cysts in the Spinal Cord

We studied survival of rat ensheathing cells after transplantation into experimental posttraumatic cysts. These cells were prepared according to our original protocol, labeled with intravital membrane dye PKH26, and transplanted into posttraumatic cysts of the spinal cord. The presence of cysts was verified by magnetic resonance imaging. Olfactory ensheathing cells were detected in the spinal cord by the immunofluorescence method. It was shown that rat olfactory ensheathing cells survived in the spinal cord over 4 weeks and their migration was observed. High survival rate and the possibility of obtaining olfactory ensheathing cells from the olfactory mucosa of patients for creation of an autologous preparation allow considering them as very promising material for the treatment of patients with posttraumatic cysts of the spinal cord.

Does cigarette smoke exposure lead to histopathological alterations in the olfactory epithelium? An electron microscopic study on a rat model

OBJECTIVE

This study was conducted to examine the influence of smoke exposure of variable duration on the ultrastructure of and histopathologic and morphologic alterations in the olfactory epithelium.

METHODS

A total of 24 Wistar albino rats were randomly assigned to three groups and fed a standard rat chow and tap water. Experimental rats in groups I and II were exposed to cigarette smoke in a glass cabin over a period of 2 months for 5 or 15 min, respectively, four times daily; control rats (group III) were not exposed to cigarette smoke. After dissection, all tissue specimens were processed using routine procedures for TEM.

RESULTS

Groups I and II exhibited the presence of intraepithelial inflammatory cells and especially deep invaginations in the nuclear membrane of supporting cells. Extended intercellular spaces, cytoplasmic protrusions on the apical surface of supporting cells, atrophy of microvilli and olfactory neuron cilia as well as numerous electron-dense granular structures and lysosome-like structures were observed to an increasing degree from group I to group II. Particularly in group II, both supporting cells and olfactory neurons exhibited a cytoplasmic edema, mitochondrial degeneration, and numerous vacuolar structures, as well as apoptotic and minimal necrotic changes. In this group, hyperplasia of basal cells was also observed.

CONCLUSION

Our electron microscopic findings show that cigarette smoke leads to toxic degenerative changes in the rat olfactory mucosa.

The olfactory mucosa: a potential source of stem cells for hearing regeneration

The olfactory mucosa contains cells that enable it to generate new neurons and other supporting cells throughout life, allowing it to replace cells of the mucosa that have been damaged by exposure to various insults. In this article, we discuss the different types of stem cell found within the olfactory mucosa and their properties. In particular, the mesenchymal-like cells found within the lamina propria will be reviewed in detail. In addition, we discuss potential applications of olfactory-derived stem cells toward hearing regeneration secondary to either inner hair cell loss or primary or secondary auditory nerve degeneration.

Isolation of Rat Olfactory Ensheathing Cells and Their Use in the Therapy of Posttraumatic Cysts of the Spinal Cord

We evaluated the efficacy of rat olfactory ensheathing cells in the therapy of experimental cysts of the spinal cord. Improvement of the motor function of the hind limbs after transplantation of the olfactory ensheathing cells into the posttraumatic spinal cord cysts rats was found. We also determined the required number of cells for transplantation and demonstrated a neuroprotective effect of this dosage. For further clinical studies, autologous tissue-specific cell preparation of olfactory ensheathing cells has to be created. Cell therapy in combination surgical and pharmacological treatment will substantially improve the quality of life of patients with posttraumatic spinal cord cysts.

The Route by Which Intranasally Delivered Stem Cells Enter the Central Nervous System

Intranasal administration is a promising route of delivery of stem cells to the central nervous system (CNS). Reports on this mode of stem cell delivery have not yet focused on the route across the cribriform plate by which cells move from the nasal cavity into the CNS. In the current experiments, human mesenchymal stem cells (MSCs) were isolated from Wharton’s jelly of umbilical cords and were labeled with extremely bright quantum dots (QDs) in order to track the cells efficiently. At 2 h after intranasal delivery in immunodeficient mice, the labeled cells were found under the olfactory epithelium, crossing the cribriform plate adjacent to the fila olfactoria, and associated with the meninges of the olfactory bulb. At all times, the cells were separate from actual nerve tracts; this location is consistent with them being in the subarachnoid space (SAS) and its extensions through the cribriform plate into the nasal mucosa. In their location under the olfactory epithelium, they appear to be within an expansion of a potential space adjacent to the turbinate bone periosteum. Therefore, intranasally administered stem cells appear to cross the olfactory epithelium, enter a space adjacent to the periosteum of the turbinate bones, and then enter the SAS via its extensions adjacent to the fila olfactoria as they cross the cribriform plate. These observations should enhance understanding of the mode by which stem cells can reach the CNS from the nasal cavity and may guide future experiments on making intranasal delivery of stem cells efficient and reproducible.

Light and scanning electron microscopy of the olfactory mucosa in the rufous sengi (Elephantulus rufescens)

Sengis are eutherian insectivores belonging to superorder Afrotheria, a recently defined clade of mammals that diverged from other placentals over 100 million years ago. In this study, a histological and ultrastructural analysis was carried out on the olfactory mucosa (OM) of the rufous sengi (Elephantulus rufescens) and the data were compared with those reported earlier in the dog (Canis familiaris) and the sheep (Ovis aries), whose dietary lifestyles are carnivorous and herbivorous, respectively. Qualitatively, the microstructure of the sengi's OM was basically similar to that of the other eutherian mammals except for differences in the pattern of cilia projection from the dendritic knobs of the olfactory receptor neurons (ORNs) and distribution of Bowman's glands within the lamina propria of the OM. On morphometry, significant differences (p < .05) were recorded with respect to olfactory epithelial (OE) thickness between the sengi (65.4 ± 2.6 μm) and the other species. ORN packing density and cilia number/ORN knob varied markedly only between the sengi (73.8 ± 5.4 mm^-2  × 10³ and 15 ± 4, respectively) and the sheep. No remarkable differences were noted in regard to ORN bundle diameters between sengis (62.7 ± 12.5 μm) and the other species. The observed differences in OM structural refinement may be attributed to olfactory function demand levels related to feeding lifestyles and ecology. Myrmecophagous insectivory, social monogamy, absentee maternal care and exposed sheltering habits are behavioural features that may warrant substantial OM modification in sengis.

Prion protein amplification techniques

Protein amplification techniques exploit the ability of PrP^TSE to induce a conformational change in prion protein (PrP) in a continuous fashion, so that the small amount of PrP^TSE found in tissues and biologic fluids in prion diseases can be amplified to a point where they are detectable by conventional laboratory techniques. The most widely used protein aggregation assays are protein misfolding cyclic amplification assay (PMCA) and real-time quaking-induced conversion (RT-QuIC). These assays have been used extensively in both animal and human prion disease in studies ranging from the development of diagnostics, understanding disease transmission potential, to investigating mechanisms underlying neurodegeneration. In human prion disease, cerebrospinal fluid (CSF) RT-QuIC analysis has been shown to be a highly sensitive and specific test for sporadic Creutzfeldt-Jakob disease (sCJD) and has now been included in the diagnostic criteria. It is also a useful investigation for some genetic forms of prion disease where other cerebrospinal fluid tests may be negative. PMCA shows great potential for the diagnosis of variant CJD (vCJD) and has the ability to distinguish vCJD from sCJD, which may become increasingly important with emergence of a patient with neuropathologically confirmed vCJD associated with PRNP codon129MV, which indicates that a new wave of vCJD cases is likely and that these may be difficult to distinguish from sCJD.

Increased Regenerative Capacity of the Olfactory Epithelium in Niemann-Pick Disease Type C1

Niemann–Pick disease type C1 (NPC1) is a fatal neurovisceral lysosomal lipid storage disorder. The mutation of the NPC1 protein affects the homeostasis and transport of cholesterol and glycosphingolipids from late endosomes/lysosomes to the endoplasmic reticulum resulting in progressive neurodegeneration. Since olfactory impairment is one of the earliest symptoms in many neurodegenerative disorders, we focused on alterations of the olfactory epithelium in an NPC1 mouse model. Previous findings revealed severe morphological and immunohistochemical alterations in the olfactory system of NPC1^−/− mutant mice compared with healthy controls (NPC1^+/+). Based on immunohistochemical evaluation of the olfactory epithelium, we analyzed the impact of neurodegeneration in the olfactory epithelium of NPC1^−/− mice and observed considerable loss of mature olfactory receptor neurons as well as an increased number of proliferating and apoptotic cells. Additionally, after administration of two different therapy approaches using either a combination of miglustat, 2-hydroxypropyl-β-cyclodextrin (HPβCD) and allopregnanolone or a monotherapy with HPβCD, we recorded a remarkable reduction of morphological damages in NPC1^−/− mice and an up to four-fold increase of proliferating cells within the olfactory epithelium. Numbers of mature olfactory receptor neurons doubled after both therapy approaches. Interestingly, we also observed therapy-induced alterations in treated NPC1^+/+ controls. Thus, olfactory testing may provide useful information to monitor pharmacologic treatment approaches in human NPC1.

Development of the main olfactory system and main olfactory epithelium-dependent male mating behavior are altered in Go-deficient mice

In mammals, initial detection of olfactory stimuli is mediated by sensory neurons in the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). The heterotrimeric GTP-binding protein Go is widely expressed in the MOE and VNO of mice. Early studies indicated that Go expression in VNO sensory neurons is critical for directing social and sexual behaviors in female mice [Oboti L, et al. (2014) BMC Biol 12:31]. However, the physiological functions of Go in the MOE have remained poorly defined. Here, we examined the role of Go in the MOE using mice lacking the α subunit of Go Development of the olfactory bulb (OB) was perturbed in mutant mice as a result of reduced neurogenesis and increased cell death. The balance between cell types of OB interneurons was altered in mutant mice, with an increase in the number of tyrosine hydroxylase-positive interneurons at the expense of calbindin-positive interneurons. Sexual behavior toward female mice and preference for female urine odors by olfactory sensory neurons in the MOE were abolished in mutant male mice. Our data suggest that Go signaling is essential for the structural and functional integrity of the MOE and for specification of OB interneurons, which in turn are required for the transmission of pheromone signals and the initiation of mating behavior with the opposite sex.

A large-scale quantitative EM study on activation of olfactory glands shows no effect of cholinergic agents

Little is known about olfactory glands' regulation despite their presumed importance for normal functioning of the cilia of olfactory neurons. The aim of this study was to establish an assay for olfactory gland activation by using large-scale quantitative electron microscopy (EM). In addition we wanted to test the hypothesis that cholinergic drugs activate the olfactory glands, by using our newly established EM assay. In total, over 70 000 secretory gland vesicles were quantified in over 3000 cells. Olfactory gland cell size (40.8 µm² ± 2.0 SD), vesicle diameter (812 nm ± 57 SD) and vesicles per cell (21.6 ± 4.2 SD) were also quantified. The vesicle percentage of the cell area varied between 24% and 30%. In a blinded study we found no significant effects of cholinergic agents on parameters of vesicle number or vesicle diameter. Unexpectedly, pilocarpine treatment increased olfactory gland size, probably by inducing cell swelling. In conclusion, we have established a quantitative EM assay for olfactory gland activation and provided new data on basic olfactory gland cell characteristics. By using the EM assay, olfactory glands are shown not to be activated by cholinergic agents, which indicates an alternative regulation pathway or constitutive secretion from olfactory glands.

Quantitative olfactory disorders and occupational exposure to phenolic resins

BACKGROUND

To investigate whether exposure to phenolic resins (PR) is associated with quantitative olfactory disorders (QOD), a cross-sectional study of self-reported olfactory impairment (SROI) was performed in occupationally exposed subjects.

MATERIAL AND METHODS

Sixty-six workers (45 males, 21 females) at the age (mean ± standard deviation) of 39.8±10.15 years old were divided into 3 exposure groups on the basis of biological exposure indices (BEI) for urinary phenols. It was asked whether the sense of smell has been normal or abnormal during the recent 2 months: the participants were eventually divided into self-reported normosmic, hyposmic, hyperosmic groups.

RESULTS

Prevalence of the SROI was 45.5%, with 21 (31.8%) workers complaining about the hyposmia, 12 (18.2%) - anosmia and 9 (13.6%) - hyperosmia. In univariate analyses, female sex was associated with the SROI and the hyperosmia. Highly exposed workers showed the SROI more frequently (odds ratio (OR) = 4.714; 95% confidence interval (CI): 1.077-20.626) than those not exposed (reference) or low exposed (OR = 1.333; 95% CI: 0.416-4.274). In multivariate analyses, female sex was the main risk factor for the SROI (adjusted odds ratio (ORa) = 5.622; 95% CI: 1.525-20.722) and the hyperosmia (ORa = 25.143; 95% CI: 2.379-265.7) but a high exposure to phenol (ORa = 11.133; 95% CI: 1.060-116.9) was the main risk factor for the anosmia.

CONCLUSIONS

This study has found slight evidence among the cross-section of chemical industry workers that the exposure to phenol may be associated with the SROI. On the other hand, self-reporting of the QOD may be biased by personal factors and further research with objective measurement is therefore required. Med Pr 2016;67(2):173-186.

Factors That Improve RT-QuIC Detection of Prion Seeding Activity

Rapid and sensitive detection of prions is important in managing prion diseases. The real-time quaking-induced conversion (RT-QuIC) assay for prion seeding activity has been applied to many prion diseases and provides for specific antemortem diagnostic testing. We evaluated RT-QuIC’s long-term consistency and varied multiple reaction parameters. Repeated assays of a single scrapie sample using multiple plate readers and recombinant prion protein (rPrP^Sen) substrates gave comparable results. N-terminal truncated hamster rPrP^Sen (residues 90–231) hastened both prion-seeded and prion-independent reactions but maintained a clear kinetic distinction between the two. Raising temperatures or shaking speeds accelerated RT-QuIC reactions without compromising specificity. When applied to nasal brushings from Creutzfeldt-Jakob disease patients, higher temperatures accelerated RT-QuIC kinetics, and the use of hamster rPrP^Sen (90–231) strengthened RT-QuIC responses. Elongation of shaking periods reduced scrapie-seeded reaction times, but continuous shaking promoted false-positive reactions. Furthermore, pH 7.4 provided for more rapid RT-QuIC reactions than more acidic pHs. Additionally, we show that small variations in the amount of sodium dodecyl sulfate (SDS) significantly impacted the assay. Finally, RT-QuIC performed in multiplate thermoshakers followed by fluorescence readings in separate plate readers enhanced assay throughput economically. Collectively, these results demonstrate improved speed, efficacy and practicality of RT-QuIC assays and highlight variables to be optimized for future applications.

Vaccination Is More Effective Than Prophylactic Oseltamivir in Preventing CNS Invasion by H5N1 Virus via the Olfactory Nerve

BACKGROUND

Influenza A viruses can replicate in the olfactory mucosa and subsequently use the olfactory nerve to enter the central nervous system (CNS). It is currently unknown whether intervention strategies are able to reduce or prevent influenza virus replication within the olfactory mucosa and subsequent spread to the CNS. Therefore, we tested the efficacy of homologous vaccination and prophylactic oseltamivir to prevent H5N1 virus CNS invasion via the olfactory nerve in our ferret model.

METHODS

Ferrets were vaccinated intramuscularly or received oseltamivir (5 mg/kg twice daily) prophylactically before intranasal inoculation of highly pathogenic H5N1 virus (A/Indonesia/05/2005) and were examined using virology and pathology.

RESULTS

Homologous vaccination reduced H5N1 virus replication in the olfactory mucosa and prevented subsequent virus spread to the CNS. However, prophylactic oseltamivir did not prevent H5N1 virus replication in the olfactory mucosa sufficiently, resulting in CNS invasion via the olfactory nerve causing a severe meningoencephalitis.

CONCLUSIONS

Within our ferret model, vaccination is more effective than prophylactic oseltamivir in preventing CNS invasion by H5N1 virus via the olfactory nerve. This study highlights the importance of including the olfactory mucosa, olfactory nerve, and CNS tissues in future vaccine and antiviral studies, especially for viruses with a known neurotropic potential.

Human olfactory stem cells for injured facial nerve reconstruction in a rat model

BACKGROUND

The purpose of this study was to show the efficacy of olfactory stem cells for injured facial nerve reconstruction in a rat model.

METHODS

Olfactory stem cells were isolated from the olfactory mucosa of human participants. A 2-mm excision was performed on the right facial nerve of all rats. Reconstruction was performed with a conduit in group 1 (n = 9); a conduit and phosphate-buffered saline in group 2 (n = 9); and a conduit and labeled olfactory stem cell in group 3 (n = 9). Rats were followed for whisker movements and electroneuronography (ENoG) analyses.

RESULTS

The whisker-movement scores for group 3 were significantly different from other groups (p < .001). ENoG showed that the amplitude values for group 3 were significantly different from group 1 and group 2 (p = .030; p < .001). Group 3 showed marked olfactory stem cell under a fluorescence microscope.

CONCLUSION

This study suggests that olfactory stem cells may be used as a potent cellular therapy for accelerating the regeneration of peripheral nerve injuries. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2011-E2020, 2016.

Can we use peripheral tissue biopsies to diagnose Parkinson's disease? A review of the literature

Phosphorylated α-synuclein (phosαSYN) containing inclusions in neurons (Lewy bodies, LB) and nerve terminals (Lewy neurites, LN), the pathological hallmark of Parkinson's disease (PD), are not confined to the central nervous system, but have also been reported in peripheral tissues. However, the usefulness of αSYN/phosαSYN detection in tissues accessible to biopsies as a reliable biomarker for prodromal PD remains unclear. A systematic review of studies using biopsies of skin, olfactory and gastrointestinal (GI) tissues was conducted to evaluate the sensitivity and specificity of both αSYN and phosαSYN staining in PD patients. Data analysis was hampered by the diversity of the methods used, e.g. choice of biopsy sites, tissue processing, staining protocols and evaluation of the findings. Tissue obtained from GI tract/salivary glands (13 post-mortem, 13 in vivo studies) yielded the highest overall sensitivity and specificity compared to skin (three post-mortem, eight in vivo studies) and olfactory mucosa/bulb (six post-mortem studies, one in vivo study). In contrast to phosαSYN, αSYN was more consistently detectable in peripheral tissues of healthy controls. GI tract/salivary glands appear to be the most promising candidate tissue for peripheral biopsy-taking. phosαSYN is considered as the marker of choice to delineate pathological aggregates from normal αSYN regularly found in peripheral neural tissues. However, the sensitivity and specificity of phosαSYN are not yet acceptable for using phosαSYN as a reliable peripheral biomarker for PD in clinical routine. Further refinement regarding the interpretation of the peripheral αSYN/phosαSYN burden and the phenotypical definition of peripheral LB/LN is needed to optimize screening methods for prodromal PD.

Mapping the nasal airways: using histology to enhance CT-based three-dimensional reconstruction in Nycticebus

Three-dimensional reconstructions of imaging data are an increasingly common approach for studying anatomical structure. However, certain aspects of anatomy, including microscopic structure and differentiating tissue types, continue to benefit from traditional histological analyses. We present here a detailed methodology for combining data from microCT and histological imaging to create 3D virtual reconstructions for visualization and further analyses. We used this approach to study the distribution of olfactory mucosa on ethmoturbinal I of an adult pygmy slow loris, Nycticebus pygmaeus. MicroCT imaging of the specimen was followed by processing, embedding, and sectioning for histological analysis. We identified corresponding features in the CT and histological data, and used these to reconstruct the plane of section in the CT volume. The CT volume was then digitally re-sliced, such that orthogonal sections of the CT image corresponded to histological sections. Histological images were annotated for the features of interest (in this case, the contour of soft tissue on ethmoturbinal I and the extent of olfactory mucosa), and annotations were transferred to binary masks in the CT volume. These masks were combined with density-based surface reconstructions of the skull to create an enhanced 3D virtual reconstruction, in which the bony surfaces are coded for mucosal function. We identified a series of issues that may be raised in this approach, for example, deformation related to histological processing, and we make recommendations for addressing these issues. This method provides an evidence-based approach to 3D visualization and analysis of microscopic features in an anatomic context.

Patient-derived olfactory mucosa for study of the non-neuronal contribution to amyotrophic lateral sclerosis pathology

Amyotrophic lateral sclerosis (ALS) is a degenerative motor neuron disease which currently has no cure. Research using rodent ALS models transgenic for mutant superoxide dismutase 1 (SOD1) has implicated that glial–neuronal interactions play a major role in the destruction of motor neurons, but the generality of this mechanism is not clear as SOD1 mutations only account for less than 2% of all ALS cases. Recently, this hypothesis was backed up by observation of similar effects using astrocytes derived from post-mortem spinal cord tissue of ALS patients which did not carry SOD1 mutations. However, such necropsy samples may not be easy to obtain and may not always yield viable cell cultures. Here, we have analysed olfactory mucosa (OM) cells, which can be easily isolated from living ALS patients. Disease-specific changes observed when ALS OM cells were co-cultured with human spinal cord neurons included decreased neuronal viability, aberrant neuronal morphology and altered glial inflammatory responses. Our results show the potential of OM cells as new cell models for ALS.

Olfaction in neurologic and neurodegenerative diseases: a literature review

Introduction Loss of smell is involved in various neurologic and neurodegenerative diseases, such as Parkinson disease and Alzheimer disease. However, the olfactory test is usually neglected by physicians at large.

Objective The aim of this study was to review the current literature about the relationship between olfactory dysfunction and neurologic and neurodegenerative diseases.

Data Synthesis Twenty-seven studies were selected for analysis, and the olfactory system, olfaction, and the association between the olfactory dysfunction and dementias were reviewed. Furthermore, is described an up to date in olfaction.

Conclusion Otolaryngologist should remember the importance of olfaction evaluation in daily practice. Furthermore, neurologists and physicians in general should include olfactory tests in the screening of those at higher risk of dementia.

Amyloid-aβ Peptide in olfactory mucosa and mesenchymal stromal cells of mild cognitive impairment and Alzheimer's disease patients

Patients with mild cognitive impairment (MCI) or Alzheimer's disease (AD) might develop olfactory dysfunction that correlates with progression of disease. Alteration of olfactory neuroepithelium associated with MCI may be useful as predictor of cognitive decline. Biomarkers with higher sensitivity and specificity would allow to understand the biological progression of the pathology in association with the clinical course of the disease. In this study, magnetic resonance images, apolipoprotein E (ApoE) load, Olfactory Connecticut test and Montreal Cognitive Assessment (MoCA) indices were obtained from noncognitive impaired (NCI), MCI and AD patients. We established a culture of patient-derived olfactory stromal cells from biopsies of olfactory mucosa (OM) to test whether biological properties of mesenchymal stromal cells (MSC) are concurrent with MCI and AD psychophysical pathology. We determined the expression of amyloid Aβ peptides in the neuroepithelium of tissue sections from MCI and AD, as well as in cultured cells of OM. Reduced migration and proliferation of stromal (CD90(+) ) cells in MCI and AD with respect to NCI patients was determined. A higher proportion of anosmic MCI and AD cases were concurrent with the ApoE ε4 allele. In summary, dysmetabolism of amyloid was concurrent with migration and proliferation impairment of patient-derived stem cells.

Transplanted human adipose tissue-derived stem cells engraft and induce regeneration in mice olfactory neuroepithelium in response to dichlobenil subministration

We used immunodeficient mice, whose dorsomedial olfactory region was permanently damaged by dichlobenil inoculation, to test the neuroregenerative properties of transplanted human adipose tissue-derived stem cells after 30 and 60 days. Analysis of polymerase chain reaction bands revealed that stem cells preferentially engrafted in the lesioned olfactory epithelium compared with undamaged mucosa of untreated transplanted mice. Although basal cell proliferation in untransplanted lesioned mice did not give rise to neuronal cells in the olfactory mucosa, we observed clusters of differentiating olfactory cells in transplanted mice. After 30 days, and even more at 60 days, epithelial thickness was partially recovered to normal values, as also the immunohistochemical properties. Functional reactivity to odorant stimulation was also confirmed through electro-olfactogram recording in the dorsomedial epithelium. Furthermore, we demonstrated that engrafted stem cells fused with mouse cells in the olfactory organ, even if heterokaryons detected were too rare to hypothesize they directly repopulated the lesioned epithelium. The data reported prove that the migrating transplanted stem cells were able to induce a neuroregenerative process in a specific lesioned sensory area, enforcing the perspective that they could become an available tool for stem cell therapy.

Autograft-derived spinal cord mass following olfactory mucosal cell transplantation in a spinal cord injury patient: Case report

Over the last decade, human cell transplantation and neural stem cell trials have examined the feasibility and safety of these potential therapies for treatment of a variety of neurological disorders. However, significant safety concerns have surrounded these trials due to the possibility of ectopic, uncontrolled cellular growth and tumor formation. The authors present the case of an 18-year-old woman who sustained a complete spinal cord injury at T10-11. Three years after injury, she remained paraplegic and underwent olfactory mucosal cell implantation at the site of injury. She developed back pain 8 years later, and imaging revealed an intramedullary spinal cord mass at the site of cell implantation, which required resection. Intraoperative findings revealed an expanded spinal cord with a multicystic mass containing large amounts of thick mucus-like material. Histological examination and immunohistochemical staining revealed that the mass was composed mostly of cysts lined by respiratory epithelium, submucosal glands with goblet cells, and intervening nerve twigs. This is the first report of a human spinal cord mass complicating spinal cord cell transplantation and neural stem cell therapy. Given the prolonged time to presentation, safety monitoring of all patients with cell transplantation and neural stem cell implantation should be maintained for many years.

Endothelin uncouples gap junctions in sustentacular cells and olfactory ensheathing cells of the olfactory mucosa

Several factors modulate the first step of odour detection in the rat olfactory mucosa (OM). Among others, vasoactive peptides such as endothelin might play multifaceted roles in the different OM cells. Like their counterparts in the central nervous system, the olfactory sensory neurons are encompassed by different glial-like non-neuronal OM cells; sustentacular cells (SCs) surround their cell bodies, whereas olfactory ensheathing cells (OECs) wrap their axons. Whereas SCs maintain both the structural and ionic integrity of the OM, OECs assure protection, local blood flow control and guiding of olfactory sensory neuron axons toward the olfactory bulb. We previously showed that these non-neuronal OM cells are particularly responsive to endothelin in vitro. Here, we confirmed that the endothelin system is strongly expressed in the OM using in situ hybridization. We then further explored the effects of endothelin on SCs and OECs using electrophysiological recordings and calcium imaging approaches on both in vitro and ex vivo OM preparations. Endothelin induced both robust calcium signals and gap junction uncoupling in both types of cells. This latter effect was mimicked by carbenoxolone, a known gap junction uncoupling agent. However, although endothelin is known for its antiapoptotic effect in the OM, the uncoupling of gap junctions by carbenoxolone was not sufficient to limit the cellular death induced by serum deprivation in OM primary culture. The functional consequence of the endothelin 1-induced reduction of the gap junctional communication between OM non-neuronal cells thus remains to be elucidated.