Type 1 Allergy-Induced Endolymphatic Hydrops and the Suppressive Effect of H1-Receptor Antagonist (Olopatadine Hydrochloride)

The clinical manifestation and treatment of Meniere's Disease from the viewpoint of the water homeostasis of the inner ear

Endolymphatic hydrops, a pathological feature of Ménière's disease, has been experimentally and clinically confirmed to be influenced by the blood circulation of vasopressin (VP). VP is a well-known hormonal regulator of water homeostasis. In addition, VP is influenced by various environmental changes, dehydration, fluctuation of atmospheric pressure, pregnancy, and other factors. Furthermore, VP is a key regulator of the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is a major neuroendocrine system that controls reactions to emotional and physical stresses, as well as the sleep/wake cycle (circadian rhythm). Therefore, VP is susceptible to change via the HPA axis. This review considers possible mechanisms of the formation of endolymphatic hydrops from the perspective of the vasopressin-aquaporin 2 system.

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.

Histamine and Its Receptors in the Mammalian Inner Ear: A Scoping Review

BACKGROUND

Histamine is a widely distributed biogenic amine with multiple biological functions mediated by specific receptors that determine the local effects of histamine. This review aims to summarize the published findings on the expression and functional roles of histamine receptors in the inner ear and to identify potential research hotspots and gaps.

METHODS

A search of the electronic databases PubMed, Web of Science, and OVID EMBASE was performed using the keywords histamine, cochlea*, and inner ear. Of the 181 studies identified, 18 eligible publications were included in the full-text analysis.

RESULTS

All four types of histamine receptors were identified in the mammalian inner ear. The functional studies of histamine in the inner ear were mainly in vitro. Clinical evidence suggests that histamine and its receptors may play a role in Ménière's disease, but the exact mechanism is not fully understood. The effects of histamine on hearing development remain unclear.

CONCLUSIONS

Existing studies have successfully determined the expression of all four histamine receptors in the mammalian inner ear. However, further functional studies are needed to explore the potential of histamine receptors as targets for the treatment of hearing and balance disorders.

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.

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.

A possible mechanism of the formation of endolymphatic hydrops and its associated inner ear disorders

The pathology of Meniere's disease (MD) is well established to be endolymphatic hydrops. However, the mechanism underlying deafness and vertigo of MD or idiopathic endolymphatic hydrops is still unknown. In order to evaluate the pathogenesis of deafness and vertigo in MD, it seems to be rational to investigate the interrelationship between hydrops and inner ear disorders using animals with experimentally-induced endolymphatic hydrops. In spite of intense efforts by many researchers, the mechanism of vertiginous attack has been unexplained, because animals with experimental hydrops usually did not show vertiginous attack. Recently, there are two reports to succeed to evoke vertiginous attack in animals with experimental hydrops. In the present paper were first surveyed past proposals about underlying mechanism of the development of hydrops and inner ear disorders associated with hydrops, and were discussed the pathogenetic mechanism of vertiginous attack in hydrops. In conclusion, abrupt development of hydrops was thought to play a pivotal role in the onset of vertiginous seizure.

A Nationwide, Population-based Cohort Study on Potential Autoimmune Association of Ménière Disease to Atopy and Vitiligo

Ménière disease (MD), an idiopathic disorder of sensorineural hearing loss and vertigo, shares many similarities with two common skin conditions, atopic dermatitis (AD) and vitiligo. Recent studies have suggested that MD may be related to or triggered by autoimmune conditions, notably Hashimoto thyroiditis and alopecia areata. These evidences led to the authors contemplating the possibility of immunological bridge between MD and the two skin conditions. The authors have tested this hypothesis with population-based cohort from the National Health Insurance Service Database of Korea. A cohort of 1.1 million patients was extracted from the database. Using χ² tests, prevalence of the two skin disorders in relation to MD status was analysed. In MD patients, the odds ratios for having concurrent AD and vitiligo were 0.717 (95% CI, 0.535–0.962, p = 0.026) and 2.149 (95% CI, 1.396–3.308, p = 0.001), respectively. Females and older patients were more than twice likely to be affected by the two skin conditions. The relationship between vitiligo and MD was significant in younger subgroup only. Socio-economic subgroup analysis revealed the observed patterns are primarily a middle-upper class phenomenon. Uncertainty regarding temporal sequence of onset, and lack of detail on disease severity and subtype kept the study from more refined conclusion. In concluding, AD and vitiligo might be linked to MD through T_reg-driven action of cellular immunity, but further big data-based investigations must follow.

Localization of histamine (H1, H2, H3 and H4) receptors in mouse inner ear

Conclusion The present findings show that all four types of histamine receptors (H1R, H2R, H3R, and H4R) are present in the inner ear, thus supporting the hypothesis that histamine plays a physiological role in the inner ear. Objective To analyse the presence of histamine receptors in the normal mouse inner ear. Methods CBA/J mice were used in this study. The localization of H1R, H2R, H3R, and H4R in the inner ear, i.e. cochlea, vestibular end organs, vestibular ganglion, and endolymphatic sac, was studied by real-time PCR and immunohistochemistry. Results The mRNA for each receptor sub-type was detected in the inner ear. In the immunohistochemical study, the organ of Corti, spiral ganglion, vestibular ganglion, vestibular sensory epithelium, and endolymphatic sac cells showed an immunofluorescent reaction to all histamine receptors.