Ménière’s disease and allergy: allergens and cytokines

Exploring causal correlations between inflammatory cytokines and Ménière's disease: a Mendelian randomization

Objectives

Previous studies have highlighted associations between certain inflammatory cytokines and Ménière's Disease (MD), such as interleukin (IL) -13 and IL-1β. This Mendelian randomization aims to comprehensively evaluate the causal relationships between 91 inflammatory cytokines and MD.

Methods

A comprehensive two-sample Mendelian randomization (MR) analysis was conducted to determine the causal association between inflammatory cytokines and MD. Utilizing publicly accessible genetic datasets, we explored causal links between 91 inflammatory cytokines and MD risk. Comprehensive sensitivity analyses were employed to assess the robustness, heterogeneity, and presence of horizontal pleiotropy in our findings.

Results

Our findings indicate that MD causally influences the levels of two cytokine types: IL-10 (P=0.048, OR=0.945, 95%CI =0.894~1.000) and Neurotrophin-3 (P=0.045, OR=0954, 95%CI =0.910~0.999). Furthermore, three cytokines exhibited significant causal effects on MD: CD40L receptor (P=0.008, OR=0.865, 95%CI =0.777-0.963), Delta and Notch-like epidermal growth factor-related receptor (DNER) (P=0.010, OR=1.216, 95%CI =1.048-1.412), and STAM binding protein (P=0.044, OR=0.776, 95%CI =0.606-0.993).

Conclusion

This study suggests that the CD40L receptor, DNER, and STAM binding protein could potentially serve as upstream determinants of MD. Furthermore, our results imply that when MD is regarded as the exposure variable in MR analysis, it may causally correlate with elevated levels of IL-10 and Neurotrophin-3. Using these cytokines for MD diagnosis or as potential therapeutic targets holds great clinical significance.

Unveiling the Allergy-Meniere Connection: Exploring the Impact of Allergen Positivity on Meniere's Disease Severity

Meniere's Disease is a rare ear disorder that can cause severe morbidity to the patient and has no definitive treatment to date. Endolymphatic hydrops is the critical event. Though symptomatology is well understood, the exact etiology of Endolymphatic hydrops attack is still unclear. Twenty-five consecutive patients of Meniere's Disease diagnosed in the Vertigo clinic aged 12 to 70 years were included. Their allergic status was evaluated using a skin prick test. Allergic and non-allergic patients were then identified. Comparison between the two groups was made to identify the effect of allergy on the severity of symptoms using vertigo scales, Functional level scale, Dizziness handicap index, and Pure tone average staging. The prevalence of allergy among Meniere's Disease patients was 56%. The most common allergen found in our study was tyrophagus(n = 8). Polysensitization was more common(n = 12). Airborne allergens were more common than food allergens. There was no significant relationship between the severity scales and the allergen positivity status (p > 0.05). The prevalence of allergy is more among patients with Meniere's Disease. The Endolymphatic sac is allergy prone. The occurrence of endolymphatic hydrops may be due to a cross-reaction of allergen-induced IgE antibodies to self-antigen. Management of the specific allergen may help decrease symptomatology in these patients. Allergen-specific therapies have a promising role in the treatment of allergic conditions and provide a long-term symptom-free period in affected individuals. This can be applied in patients with Meniere's Disease having associated allergic features based on their skin prick test results.

A systematic review of the clinical evidence for an association between type I hypersensitivity and inner ear disorders

Inner ear disorders have a variety of causes, and many factors can contribute to the exacerbation of cochlear and vestibular pathology. This systematic review aimed to analyze clinical data on the coexistence and potential causal interaction between allergic diseases and inner ear conditions. A search of PubMed and Web of Science identified 724 articles, of which 21 were selected for full-text analysis based on inclusion and exclusion criteria. The epidemiologic evidence found overwhelmingly supports an association between allergic disease and particular inner ear disorders represented by a high prevalence of allergic reactions in some patients with Ménière's disease (MD), idiopathic sudden sensorineural hearing loss (ISSHL), and acute low-tone hearing loss (ALHL). In addition, patients with MD, ISSHL, and ALHL had higher levels of total serum IgE than healthy subjects. Finally, in some cases, changes in cochlear potential may have been induced by antigen exposure, while desensitization alleviated allergy and inner ear-related symptoms. The exact mechanism of interaction between the auditory/vestibular and immune systems is not fully understood, and further clinical and basic research is needed to understand the relationship between the two systems fully.

Ménière's disease and allergy: Epidemiology, pathogenesis, and therapy

The etiology of Ménière's disease (MD) remains controversial. Allergies are potential extrinsic factors that, in conjunction with underlying intrinsic factors, may cause MD. The link between allergies and MD was first described in 1923. For nearly a century, studies have demonstrated a possible link between allergies and MD, even though a causal relationship has not been definitively determined. Previous reviews have mainly focused on clinical epidemiology studies of patients. In this review, we shed light on the association between allergies and MD not only in terms of its epidemiology, but also from an immunology, pathophysiology, and immunotherapy perspective in both patients and animal models. Patients with MD tend to have a high risk of comorbid allergies or an allergy history, showing positive allergy immunology characteristics. Other MD-related diseases, such as migraine, may also interact with allergies. Allergy mediators such as IgE may worsen the symptoms of MD. Deposits of IgE in the vestibular end organs indicate the ability of the inner ear to participate in immune reactions. Allergic challenges can induce vertigo in animals and humans. Anti-allergy therapy plays a positive role in patients with MD and animal models of endolymphatic hydrops.

Single-cell immune profiling of Meniere Disease patients

BACKGROUND

Meniere Disease (MD) is an inner ear syndrome, characterized by episodes of vertigo, tinnitus and fluctuating sensorineural hearing loss. The pathological mechanism leading to sporadic MD is still poorly understood, however an allergic inflammatory response seems to be involved in some patients with MD.

OBJECTIVE

Decipher an immune signature associated with the syndrome.

METHODS

We performed mass cytometry immune profiling on peripheral blood from MD patients and controls. We analyzed differences in state and differences in abundance of the different cellular subsets. IgE levels were quantified through ELISA on supernatant of cultured whole blood.

RESULTS

We have identified two clusters of individuals according to the single cell cytokine profile. These clusters presented differences in IgE levels, immune cell population abundance, including a reduction of CD56^dim NK-cells, and changes in cytokine expression with a different response to bacterial and fungal antigens.

CONCLUSION

Our results support a systemic inflammatory response in some MD patients that show a type 2 response with allergic phenotype, which could benefit from personalized IL-4 blockers.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Functional and Molecular Markers for Hearing Loss and Vertigo Attacks in Meniere's Disease

Meniere's disease (MD) is one of the most complicated diseases in the otologic clinic. The complexity of MD is partially due to the multifactorial etiological mechanisms and the heterogenous symptoms, including episodic vertigo, hearing loss, aural fullness and tinnitus. As a result, the diagnosis of MD and differentiating MD from other diseases with similar symptoms, such as vestibular migraine (VM), is challenging. In addition, it is difficult to predict the progression of hearing loss and the frequency of vertigo attacks. Detailed studies have revealed that functional markers, such as pure tone audiometry (PTA), electrocochleography (ECochG), vestibular evoked myogenic potential (VEMP), caloric test, video head impulse test (vHIT) and magnetic resonance imaging (MRI) could help to evaluate MD with different hearing levels and frequency of vertigo attacks. Investigations of molecular markers such as autoimmunity, inflammation, protein signatures, vasopressin and circadian clock genes in MD are still underway. This review will summarize these functional and molecular markers, address how these markers are associated with hearing loss and vertigo attacks in MD, and analyze the results of the markers between MD and VM.

Population-based study for the comorbidities and associated factors in Ménière's disease

To date, no study has reported the objective metabolic laboratory findings worldwide or the comorbidities for Ménière’s disease (MD) using a population-based design in Asian populations. The aim of this study was to investigate the comorbidities and associated factors for MD using the Korean National Health Insurance Service database. This retrospective population-based study was conducted using a data from the National Sample Cohort database from 2009 to 2015. We only enrolled patients whose records showed a prescription for MD medicine and audiometry findings as well as an appropriate diagnostic code. We also included a matched cohort without MD who were enrolled randomly and matched for sex, age, year of diagnosis, income level, and residential area with the MD group with a ratio of 10:1. We evaluated comorbidities including autoimmune, allergic, metabolic diseases and cancer and the health screening data including general characteristics (height, weight, waist circumference, body mass index, and blood pressure), laboratory findings (fasting glucose, cholesterol, triglyceride, high-density lipoproteintryglyceride (HDL) cholesterol, low-density lipoproteintryglyceride cholesterol, hemoglobin, creatinine, aspartate aminotransferase and alanine aminotransferase, and gamma-glutamyltrans- peptidase (rGT)), and general health behaviors (smoking, alcohol, and exercise) of the MD group, and compared these characteristics with those of the MD-free control group. A total of 2,013 and 20,130 participants were included in the MD and MD-free control groups (1,640 and 15,458 for health screening data). We found the increase in incidence of allergic rhinitis and allergic asthma, decrease in systolic blood pressure, HDL cholesterol, and rGT, and less frequent alcohol consumption and less prevalent smoking in the MD group. No significant differences were observed between the groups in the incidence of autoimmune diseases, and cerebro- and cardiovascular disease as well as health screening data and objective laboratory findings. Inconsistence with published studies, the results of this study suggest that the autoimmunity and metabolic disorder, and skeletal growth might not be associated with the onset of MD. Another well-designed study for other races will be needed to the generalization of this study results.

Up-Regulated Expression of Interferon-Gamma, Interleukin-6 and Tumor Necrosis Factor-Alpha in the Endolymphatic Sac of Meniere's Disease Suggesting the Local Inflammatory Response Underlies the Mechanism of This Disease

Background

Immune mediated inflammatory changes affecting the endolymphatic sac (ES) may underlie the pathology of Meniere's disease (MD). The aim of the present study was to explore the differentially expressed cytokines in ES luminal fluid (ELF) of patients with MD, and the correlation between the expression of cytokines in the ELF with that in the serum was determined by quantitatively analyzing the cytokines in human ELF and serum.

Methods

Human ELF, serum and ES tissues were collected from patients with unilateral MD and patients with acoustic neuroma (AN) during surgery. The Simoa Cytokine 6-Plex Panel kit was used to analyze the levels of cytokines in the ELF and blood samples of the patients. Immunohistochemistry and immunofluorescence were subsequently used to validate the relative expression levels of the cytokines in MD.

Results

Significant differences were identified in the expression levels of interferon-γ (IFN-γ) (P < 0.001), interleukin (IL)-6 (P = 0.008) and tumor necrosis factor-α (TNF-α) (P = 0.036) in the luminal fluid of the ES comparing between the MD and AN groups. By contrast, the levels of IFN-γ, IL-10, IL-12p70, IL-17A, IL-6 and TNF-α in the serum of the MD group were not significantly different from those of either the AN group or healthy control subjects. In addition, no significant correlations in the expression levels of cytokines compared between the ELF and serum were found for the patients in either the MD or the AN group. Finally, the detection of positive expression of TNF-α, IL-6 and IFN-γ in the epithelial cells of the majority of ES specimens from patients with MD confirmed the up-regulated expression of these cytokines in the ES of patients with MD.

Conclusions

The identification of up-regulated expression levels of TNF-α, IL-6 and IFN-γ in the ELF in the present study has provided direct evidence for an increased immunologic activity in the microenvironment of the ES in patients with unilateral MD, may suggest the local inflammatory response underlies the mechanism of this disease.

Bidirectional Transport of IgE by CD23 in the Inner Ear of Patients with Meniere's Disease

Meniere's disease (MD) is a disorder of the inner ear characterized by episodes of spontaneous vertigo, fluctuating hearing loss, and tinnitus. Recent studies have demonstrated that IgE may play a role in the pathogenesis of MD. Patients with MD (n = 103), acoustic neuroma (n = 5), and healthy subjects (n = 72) were recruited into the study. Serum from the participants was analyzed for IgE and type 2-related cytokines. IgE and CD23 expression levels in vestibular end organs of patients, C57BL/6 mice, or mouse HEI-OC1 cells were analyzed. Finally, the role of CD23 in IgE transcytosis was assessed using HEI-OC1 cells. Serum IgE was elevated in patients with MD and positively correlated with clinical symptoms. IL-4, IL-5, IL-10, IL-13, and CD23 levels were increased in patients with MD compared with the control group. In the transcytosis assay, mouse IgE was found to be bidirectionally transported across the HEI-OC1 cell monolayer. Additionally, CD23 downregulation using a small interfering RNA approach significantly reduced the efficiency of IgE transcytosis, suggesting that IgE is transported by CD23. Furthermore, exposure to IL-4 increased CD23 expression and enhanced IgE transcytosis in the HEI-OC1 cells and primary vestibular end organs. Our study indicated that IgE may play a role in the pathophysiology of MD. In addition, CD23-mediated IgE transcytosis in the hair cells may play a critical role in initiating inflammation in the inner ear. Thus, reducing the level of IgE may be a potentially effective approach for MD treatment.

Association Between Asthma and Meniere's Disease: A Nested Case-Control Study

OBJECTIVES/HYPOTHESIS

This study aimed to investigate the association between Meniere's disease and prior history of asthma.

STUDY DESIGN

A nested case-control study.

METHODS

Among the patients aged ≥40 years from the Korean National Health Insurance Service-Health Screening Cohort 2002-2015, 7,734 diagnosed with Meniere's disease between 2004 and 2015 were enrolled in this study. From the 505,834 participants without a prior history of Meniere's disease, 30,936 control participants were selected based on age, sex, income, and region of residence. The presence of a prior history of asthma before the diagnosis of Meniere's disease was compared between the Meniere's disease group and control group using conditional logistic regression with odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

Prior history of asthma was associated with 1.30 (1.21-1.39) times higher odds of Meniere's disease (E-value = 1.92 [1.71]). Both allergic asthma and nonallergic asthma patients demonstrated higher odds of Meniere's disease than the control group (adjusted OR = 1.21 [1.08-1.36] and E-value = 1.72 [1.37] for allergic asthma; adjusted OR = 1.26 [1.17-1.36] and E-value = 1.83 [1.60] for nonallergic asthma).

CONCLUSIONS

This study is the first to demonstrate a positive relationship between Meniere's disease and prior asthma history in adults. The association between prior asthma history and Meniere's disease was noted in both allergic and nonallergic asthma cases. The potential development of Meniere's disease should be considered when managing the asthma patients with dizziness or vertigo.

LEVEL OF EVIDENCE

3 Laryngoscope, 2021.

The relationship between nutrition and Ménière's disease

Ménière's disease is an inner ear disease with attacks characterized by ear fullness, tinnitus, fluctuant sensorineural hearing loss and vertigo. Although pathophysiology of the disease is not fully known, endolymphatic hydrops are believed to play a role. Although there is no certain treatment procedure for Ménière's disease, some treatments are applied to prevent attacks, to treat the symptoms that occur during the attacks, and to prevent the permanent effects of the symptoms on the hearing and balance system. Lifestyle changes, dietary modifications, diuretics, vasodilator corticosteroids, intratympanic steroids, surgical methods are some of these treatment methods. Dietary modification includes a low sodium diet, a reduction in daily alcohol and caffeine intake, a gluten-free diet, and a new dietary approach to specially processed grains, all of which are first-line treatments. The goal of this review article is to examine the relationship between MD and dietary intervention, which is frequently used in the prevention and treatment of MD attacks.

High level of IgE in acute low-tone sensorineural hearing loss: A predictor for recurrence and Meniere Disease transformation

BACKGROUND

Autoimmunity may play an important role in sudden onset sensorineural hearing loss. However, little is known about the relationship between immunoglobulin E (IgE) and acute low-tone sensorinerual hearing loss (ALHL).

OBJECTIVES

To investigate the relationship between IgE level and endolymphatic hydrops and outcomes of ALHL.

METHODS

A total of 242 subjects with sudden onset hearing loss, including 115 with ALHL and 127 with idiopathic sudden sensorineural hearing loss (ISSHL), were included in this study. Peripheral venous blood samples of 242 subjects were collected for detection. Clinical data, IgE level, and distribution of allergens were compared between the ALHL and ISSHL groups. The ALHL group received an electrocochleogram (ECochG) test and a follow-up in the outpatient unit or by telephone to evaluate outcomes.

RESULTS

Compared to the values in the ISSHL group, a significantly younger onset age (42.30±14.33 years old), higher female onset proportion (72/115, 62.61%), increased total IgE level (median: 66.47, interquartile range: 24.56, 180.96, IU/mL) and specific IgE level (median: 9.42, interquartile range: 1.42, 22.23 IU/mL) were noted in the ALHL group. A clear difference in allergen distribution was noted between the ALHL and ISSHL groups (p=.001). Total IgE and specific IgE levels were factors that contributed to the SP/AP ratio in the electrocochleogram (ECochG) (R²=0.413) in ALHL group. Finally, during the follow-up (17.61±3.46 months) for the ALHL group, 37 subjects recurred, and 17 subjects developed Meniere Disease. In the ROC curve for ALHL recurrence, the area under the curve (AUC) of total IgE was 0.709 and that of specific IgE was 0.679. For MD transformation, the AUC of total IgE was 0.736 and that of specific IgE was 0.716.

CONCLUSIONS

High IgE levels correlated with an enhanced SP/AP ratio in ALHL. High IgE levels could be used as a predictor of ALHL recurrence and MD transformation.

Evaluation of Serum Immunoreactivity to Common Indigenous Iranian Inhalation and Food Allergens in Patients with Meniere's Disease

Background: A few studies investigated the relationship between allergy and Meniere disease considering complete allergen panel. We aimed to evaluate the serum immunoreactivity in patients with Meniere's disease (MD) compared with healthy people according to common indigenous Iranian inhalation and food allergens.Methods: Thirty-nine patients with MD referred to Rasoul Akram Hospital (Tehran, Iran) were evaluated and compared with a 41 membered control group. A panel of common inhalation and food allergens (using an immunoblotting method), as well as total immunoglobulin E (IgE) level (using the sandwich enzyme-linked immunosorbent assay method), were checked on the patients' serum.Results: The mean total IgE level was 193.85 ± 175.43 IU/ml in the patients with MD and 117.61 ± 138.05 IU/ml in the control group, which was significantly higher than the other subjects in the control group (P = .016). There was a significant difference between the two groups regarding inhalation allergens such as; sweet vernal grass, cultivated rye, cultivated oat, Russian thistle, goosefoot, and rough pigweed (P = .01-0.038). Patients with MD reported more reactive to food allergens such as; rye flour, hazelnut, pepper, citrus mix 2, potato, strawberry, and celery allergens. There was a significant relationship between Meniere and serum immunoreactivity to inhalation and food allergens (both P = .001).Conclusion: Serum total IgE level in patients with MD (in both inhalation and food allergens groups) was higher than the control group, and there was a relationship between MD and immunoreactivity to common indigenous inhalation and food allergens of Iran.

Is there "hidden hearing loss" in patients with chronic rhinosinusitis?

Objective: This study was to investigate whether there is impairment of auditory function in chronic rhinosinusitis (CRS).Study sample: A total of 85 patients were allocated into either the CRS group (n = 65) or a simple deviated nasal septum group (n = 20). Both groups without other risk factors for sensorineural hearing loss exhibited normal thresholds at standard audiometric frequencies. Another group (n = 30) of healthy subjects without CRS or a deviated nasal septum were gender and age matched.Design: Analyse the results of audiology test including pure tone audiometry, an acoustic impedance test, distortion product otoacoustic emissions (DPOAE) and the auditory brainstem response (ABR) for each subject analyse the test results of for each object.Results: The group differences were statistically significant for each high-frequency pure tone (p < 0.05). The ABR showed a difference between groups in amplitude. The DPOAE pass rate of the CRS group was lower than that of the control group.Conclusions: This study showed a significant correlation between CRS and auditory impairment. CRS might impair cochlear functions by damaging inner ear hair cells and/or, outer hair cells (OHCs), consequently altering the activity of the entire auditory pathway originating in the ventral cochlear nucleus (VCN) to the inferior colliculus.

Barometric pressure and the incidence of benign paroxysmal positional vertigo

OBJECTIVES

To investigate the relationship between barometric pressure and the incidence of benign paroxysmal positional vertigo (BPPV).

METHODS

181 patients diagnosed with classic BPPV seen between 2011 and 2016 were identified. Demographic information, data of onset, and date of presentation were recorded. Historical barometric data for each of the 60 months were recorded. In addition, monthly counts of other atmospheric, infectious, and allergic variables for that time period were recorded. Correlation analysis compared monthly incidence of BPPV with absolute and relative changes in atmospheric conditions.

RESULTS

The incidence of BPPV onset demonstrated a statistically significant positive correlation with barometric pressure, where every one-unit increase in barometric pressure leads to an expected increase of 6.1 diagnoses (p = 0.0008). The correlation coefficient (r) between barometric pressure and BPPV diagnoses was 0.66 (95% CI 0.14-0.90) with a p-value of 0.0131. Other seasonal variables demonstrated correlation, though none as strong as barometric pressure.

CONCLUSIONS

Barometric pressure has been long been associated with conditions of the inner ear, though its relationship to the pathogenesis of BPPV has not been investigated. Monthly changes in barometric pressure, rather than the absolute value, may be responsible for the observed changes in incidence. These findings demonstrate a clear association between barometric pressure and BPPV that may help to explain both the etiology of BPPV and its possible connection to migraine-related conditions.

Proinflammatory cytokines and response to molds in mononuclear cells of patients with Meniere disease

Epidemiological studies have found a higher prevalence of allergic symptoms and positive prick tests in patients with Meniere’s disease (MD); however the effect of allergenic extracts in MD has not been established. Thus, this study aims to determine the effect of Aspergillus and Penicillium stimulation in cytokine release and gene expression profile in MD. Patients with MD showed higher basal levels of IL-1β, IL-1RA, IL-6 and TNF-α when compared to healthy controls. We observed that IL-1β levels had a bimodal distribution suggesting two different subgroups of patients, with low and high basal levels of cytokines. Gene expression profile in peripheral blood mononuclear cells (PBMC) showed significant differences in patients with high and low basal levels of IL-1β. We found that both mold extracts triggered a significant release of TNF-α in MD patients, which were not found in controls. Moreover, after mold stimulation, MD patients showed a different gene expression profile in PBMC, according to the basal levels of IL-1β. The results indicate that a subset of MD patients have higher basal levels of proinflammatory cytokines and the exposure to Aspergillus and Penicillium extracts may trigger additional TNF-α release and contribute to exacerbate inflammation.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

A network-based method using a random walk with restart algorithm and screening tests to identify novel genes associated with Menière's disease

As a chronic illness derived from hair cells of the inner ear, Menière’s disease (MD) negatively influences the quality of life of individuals and leads to a number of symptoms, such as dizziness, temporary hearing loss, and tinnitus. The complete identification of novel genes related to MD would help elucidate its underlying pathological mechanisms and improve its diagnosis and treatment. In this study, a network-based method was developed to identify novel MD-related genes based on known MD-related genes. A human protein-protein interaction (PPI) network was constructed using the PPI information reported in the STRING database. A classic ranking algorithm, the random walk with restart (RWR) algorithm, was employed to search for novel genes using known genes as seed nodes. To make the identified genes more reliable, a series of screening tests, including a permutation test, an interaction test and an enrichment test, were designed to select essential genes from those obtained by the RWR algorithm. As a result, several inferred genes, such as CD4, NOTCH2 and IL6, were discovered. Finally, a detailed biological analysis was performed on fifteen of the important inferred genes, which indicated their strong associations with MD.

Menière's disease

Menière's disease (MD) is a chronic multifactorial disorder of the inner ear characterized by episodic vestibular symptoms associated with sensorineural hearing loss, tinnitus, and aural pressure. Epidemiologic and genomic evidence supports a genetic susceptibility with multiple biochemical pathways involved, including the endocrine system, innate immune response, and autonomic nervous system. Allergens, infectious agents, vascular events, or genetic factors could modify inner-ear homeostasis and trigger MD. The diagnosis of MD is based on clinical criteria and requires the observation of an episodic vertigo syndrome associated with low- to medium-frequency sensorineural hearing loss and fluctuating aural symptoms (hearing loss, tinnitus, and/or fullness) in the affected ear. Headache is also found during the attacks and bilateral involvement is found in 25-40% of cases. Audiologic and vestibular assessment is recommended to monitor the clinical course. The treatment of MD is symptomatic to obtain relief of vestibular episodes and preventive to limit hearing loss progression. Treatment options include sodium restriction, betahistine, intratympanic gentamicin, or steroids and eventually surgery, such as cochlear implantation.

The link between allergy and Menière's disease

PURPOSE OF REVIEW

To examine evidence supporting the association of allergy and Menière's disease.

RECENT FINDINGS

Animal studies have shown evidence that a provoked systemic immune challenge can result in an allergic reaction within the inner ear, whereas premedication with leukotriene antagonists can prevent the development of endolymphatic hydrops. In human subjects, further data support a heightened allergic response in patients with Menière's disease, whereas pharmacological treatments that target histamine receptors help to control vertiginous symptoms. However, the relationship of migraine with a history of allergy and Menière's disease may confound this association.

SUMMARY

Although the evidence of a causal association between allergy and Menière's disease is inconclusive, the inclusion of allergy control as part of the treatment plan for Menière's disease is low risk to the patient and should be considered for patients with indications that include history of seasonal or food allergy, childhood or family history of allergy, bilateral Menière's symptoms, or a development of symptoms within a short time after exposure of food or inhaled allergen.

Is allergy related to Meniere's disease?

Meniere's disease (MD) is characterized by episodic rotational vertigo, fluctuating sensorineural hearing loss, aural pressure, and tinnitus. The cause of MD is thought to be multifactorial, with anatomic and genetic contributions. Allergy is thought to be one of the possible extrinsic factors that, when combined with underlying intrinsic factors, may lead to MD. We review the epidemiologic associations of MD and allergy and review the recent literature on the association of allergy and MD.

Corticosteroid therapy for hearing and balance disorders

This review addresses the current status of steroid therapies for hearing and vestibular disorders and how certain misconceptions may be undermining the efficacy in restoring normal ear function, both experimentally and clinically. Specific misconceptions addressed are that steroid therapy is not effective, steroid-responsive hearing loss proves an underlying inflammatory problem in the ear, and steroids only have application to the hearing disorders listed below. Glucocorticoid therapy for hearing and balance disorders has been employed for over 60 years. It is recommended in cases of sudden hearing loss, Meniére's disease, immune-mediated hearing loss, and any vestibular dysfunction suspected of having an inflammatory etiology. The predominant steroids employed today are dexamethasone, prednisone, prednisolone, and methylprednisolone. Despite years of use, little is known of the steroid responsive mechanisms in the ear that are influenced by glucocorticoid therapy. Furthermore, meta-analyses and clinical study reviews occasionally question whether steroids offer any benefit at all. Foremost in the minds of clinicians is the immune suppression and anti-inflammatory functions of steroids because of their efficacy for autoimmune hearing loss. However, glucocorticoids have a strong binding affinity for the mineralocorticoid (aldosterone) and glucocorticoid receptors, both of which are prominent in the ear. Because the auditory and vestibular end organs require tightly regulated endolymph and perilymph fluids, this ion homeostasis role of the mineralocorticoid receptor cannot be overlooked in both normal and pathologic functions of the ear. The function of the glucocorticoid receptor is to provide anti-inflammatory and antiapoptotic signals by mediating survival factors.

The role of allergy in the etiopathogenesis of idiopathic sudden sensorineural hearing loss

To evaluate the role of allergy in the etiopathogenesis of sudden hearing loss using cytokine profile, allergic parameters, and lymphocyte subgroups, a total of 31 patients aged between 30 and 62 years (mean age: 42.48 ± 15.86 years) with the diagnosis of sudden hearing loss were enrolled in the study between 2008 and 2011. The control group comprised 30 age-matched adult subjects accepted as clinically healthy individuals living in the same region with comparable socioeconomic parameters. The patient and the control group were questioned for history of allergy. Lymphocyte subgroups in the peripheral blood were evaluated using Becton-Dickinson monoclonal CD4, CD8, CD19, and CD23 antibodies. In the patient and control groups, the levels of IFN- γ, IL4, IL10, and total IgE were measured and compared between the groups. Skin test was used for detection of inhaler allergens in the patient and the control groups, and specific IgE tests were performed using the RAST method for food allergens. The Spearman's rho correlation, the unpaired t test, the Mann-Whitney U test, and the Shapiro-Wilk test were used to determine the differences between the groups. The limit for statistical significance was p < 0.05. When the patient and the control group were compared, the differences between CD4, CD23, IL4, IL10, and IgE were statistically significant. On analyses of the patients' serum samples, strongly positive correlations were determined between IgE and CD23, IL10, IL4; IL4 and IL10, CD23, CD4; IL10 and CD23, CD4 (Spearman rho, p = 0.000), while a weakly positive correlation was found between IgE and CD4 (Spearman rho, p = 0.020). A correlation between IFN-γ and CD4 was weakly negative (Spearman rho, p = 0.040). The total IgE levels were estimated to be above the normal reference ranges (0-100 IU/ml) in 25.8 % of the cases in the patient group. History of allergy was found in 61.9 % of the patients. The results of this study substantiate the role of allergy in the etiopathogenesis of sudden hearing loss. We think that during the diagnostic work-up of these patients allergy should be interrogated seriously, necessary tests should be performed, and allergy should be considered in the decision-making process of the treatment of sudden hearing loss.

Vascular Pathophysiology in Hearing Disorders

The inner ear vasculature is responsible for maintenance of the blood-labyrinth barrier, transport of systemic hormones for ion homeostasis, and supplying nutrients for metabolic functions. Unfortunately, these blood vessels also expose the ear to circulating inflammatory factors resulting from systemic diseases. Thus, while the inner ear blood vessels are critical for normal function, they also are facilitating pathologic mechanisms that result in hearing and vestibular dysfunction. In spite of these numerous critical roles of inner ear vasculature, little is known of its normal homeostatic functions and how these are compromised in disease. The objective of this review is to discuss the current concepts of vascular biology, how blood vessels naturally respond to circulating inflammatory factors, and how such mechanisms of vascular pathophysiology may cause hearing loss.

Allergic and immunologic features of Ménière's disease

Ménière's disease (MD), which by definition is idiopathic, has been ascribed to various causes, including both inhalant and food allergies. Patients with MD report higher rates of allergy history and positive skin or in vitro tests compared with a control group of patients with other otologic diseases and to the general public. Recent immunologic studies have shown higher rates of circulating immune complexes, CD4, and other immunologic components in patients with MD compared with healthy controls. Published treatment results have shown benefit from immunotherapy and/or dietary restriction for symptoms of MD in those patients who present with both allergy and MD.

Interferon-gamma suppresses Na+ -H+ exchanger in cultured human endolymphatic sac epithelial cells

Adequate regulation of endolymphatic pH is essential for maintaining inner ear function. The Na(+)-H(+) exchanger (NHE) is a major determinant of intracellular pH (pH(i)), and facilitates Na(+) and fluid absorption in various epithelia. We determined the functional and molecular expression of NHEs in cultured human endolymphatic sac (ES) epithelial cells and examined the effect of IFN-gamma on NHE function. Serial cultures of human ES epithelial cells were generated from tissue samples. The molecular expression of NHE1, -2, and -3 isoforms was determined by real-time RT-PCR. The functional activity of NHE isoforms was measured microfluorometrically using a pH-sensitive fluorescent dye, 2',7'-bis(carbonylethyl)-5(6)-carboxyfluorescein (BCECF), and a NHE-inhibitor, 3-methylsulfonyl-4-piperidinobenzoyl guanidine methanesulfonate (HOE694). NHE1, -2, and -3 mRNAs were expressed in human ES epithelial cells. Functional activity of NHE1 and -2 was confirmed in the luminal membrane of ES epithelial cells by sequentially suppressing Na(+)-dependent pH(i) recovery from intracellular acidification using different concentrations of HOE694. Treatment with IFN-gamma (50 nM for 24 h) suppressed mRNA expression of NHE1 and -2. IFN-gamma also suppressed functional activity of both NHE1 and -2 in the luminal membrane of ES epithelial cells. This study shows that NHEs are expressed in cultured human ES epithelial cells and that treatment with IFN-gamma suppresses the expression and functional activity of NHE1 and -2.

Allergy and Ménière's disease

Ménière's disease (MD), which by definition is idiopathic, has been ascribed to various causes, including both inhalant and food allergies. Patients with MD report higher rates of allergy history and positive skin or in vitro tests compared to a control group of patients with other otologic diseases and to the general public. Recent immunologic studies have shown higher rates of circulating immune complexes, CD4, and other immunologic components in patients with MD compared to normal controls. Published treatment results have shown benefit from immunotherapy and/or dietary restriction for symptoms of MD in patients with both allergy and MD.