A mouse model of autoimmune inner ear disease without endolymphatic hydrops.

Autoimmune inner ear disease (AIED) is an organ-specific disease characterized by irreversible, prolonged, and progressive hearing and equilibrium dysfunctions. The primary symptoms of AIED include asymmetric sensorineural hearing loss accompanied by vertigo, aural fullness, and tinnitus. AIED is divided into primary and secondary types. Research has been conducted using animal models of rheumatoid arthritis (RA), a cause of secondary AIED. However, current models are insufficient to accurately analyze vestibular function, and the mechanism underlying the onset of AIED has not yet been fully elucidated. Elucidation of the mechanism of AIED onset is urgently needed to develop effective treatments. In the present study, we analyzed the pathogenesis of vertigo in autoimmune diseases using a mouse model of type II collagen-induced RA. Auditory brain stem response analysis demonstrated that the RA mouse models exhibited hearing loss, which is the primary symptom of AIED. In addition, our vestibulo-oculomotor reflex analysis, which is an excellent vestibular function test, accurately captured vertigo symptoms in the RA mouse models. Moreover, our results revealed that the cause of hearing loss and vestibular dysfunction was not endolymphatic hydrops, but rather structural destruction of the organ of Corti and the lateral semicircular canal ampulla due to an autoimmune reaction against type II collagen. Overall, we were able to establish a mouse model of AIED without endolymphatic hydrops. Our findings will help elucidate the mechanisms of hearing loss and vertigo associated with AIED and facilitate the development of new therapeutic methods.

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.

[The pilot study of type â allergic reaction in Meniere's disease patients].

Objective: To evaluate the correlation between type Ⅰ allergic reaction and pathogenesis of Meniere's disease. Methods: A total of 35 (10 male vs. 25 female) patients aged between 21-66 years diagnosed with Meniere's disease were recruited to this study, mean age of them was (47.3±13.6) years. The control group consisted of 15 inpatients (5 male vs. 10 female) with pharyngolaryngeal diseases but without otologic and rhinologic abnormity, mean age was 45.4±12.8 years. Allergic prevalence, serous total immunoglobulin E( tIgE ) levels, serous specific immunoglobulin E( sIgE ) levels and subtypes of T lymphocytes were measured and compared in patients with Meniere's disease and the control group. Severity of vertigo, tinnitus and sensation of fullness were compared between Meniere's disease patients with or without allergy. Results: Allergic prevalence were significantly different (Pearson chi-square 5.832, P<0.05) between patients with Meniere's disease and the control group(57.1% vs. 20.0%). Patients with Meniere's disease report higher level of serous tIgE compared with controls, the difference is statistically significant (Z=168.000, P<0.05). However, positive rates of sIgE of food allergens and inhalant allergens were not significantly different between patients with Meniere's disease and the control group. Scores of vertiginous severity, dizziness handicap inventory (DHI) and tinnitus handicap inventory (THI) were significantly different between Meniere's disease patients with or without allergy (P<0.05). Treg and Treg/Th17 levels (Z=26.000) were much higher in Meniere's disease patients with allergy than in the controls(P<0.05). Conclusions: Patients with Meniere's disease report higher rate of allergy than the control group. Type Ⅰ allergic reaction is thought to be one of the possible reasons that may induce endolymphatic hydrops and lead to Meniere's disease.

Provocation of endolymphatic hydrops with a prick test in Meniere's disease.

This study was conducted to test the hypothesis that antigenic challenge is an important stimulative factor for an episode of endolymphatic hydrops. The study was held in a tertiary care center for patients with probable or definite Meniere's disease. The prick test, which included dietary and inhalant allergens, was applied to all patients with a Multi-Test Applicator (Lincoln Diagnostics, Decatur, Ill). Patients were tested with electrocochleography before and after the prick test. The positive allergen was diluted in 1/10 of a prick test dose, and patients were provoked and tested again. A negative summating potential/action potential (SP/AP) amplitude ratio greater than 0.5 was used as the main outcome measure. Pretest, posttest, and postprovocation SP/AP amplitude ratios were compared. A total of 80 diseased and 16 normal ears of 48 patients with Meniere's disease were assessed. All patients were found to be atopic, but none had allergic symptoms. No symptom like vertigo or fullness was seen after the prick test was performed. In all, 30 patients had tinnitus and fullness in the diseased ear, and 6 patients had vertigo after the provocation. The SP/AP ratio was greater than 0.50 in 23 diseased (29%) and 3 normal (19%) ears before the prick test. After the prick test, 62 diseased (78%) and 13 normal (81%) ears had endolymphatic hydrops. These numbers did not change much after the provocation. Results reported here support the role of antigenic stimulation for episodes of Meniere's disease. Endolymphatic hydrops was the atopic reaction that occurred in most study patients.

Endolymphatic hydrops as a cause of audio-vestibular manifestations in relapsing polychondritis.

Relapsing polychondritis (RP) is characterized by inflammation and subsequent degeneration of cartilage. We report a 61-year-old woman who had RP with audio-vestibular manifestations. She was also diagnosed as having a myelofibrosis with myeloid metaplasia (MMM). Bilateral endolymphatic hydrops (EH) was confirmed by dominant -SP/AP of the electrocochleogram (ECochG). When thalidomide and prednisolone were prescribed for the treatment of MMM, symptoms of RP -- including the inner ear dysfunction -- were ameliorated. Isosorbide, one of the osmotic diuretics commonly used for the treatment of Meniere's disease (MD) in Japan, was also effective in keeping her free from inner ear dysfunction. This is the first report to confirm the existence of EH in a patient with RP with audio-vestibular manifestations. We suppose that an immunological imbalance due to MMM, in conjunction with a specific immunogenetic background, may have played a role in the pathogenesis of RP and the formation of EH in this patient.

Autoantibodies against inner ear proteins in patients with delayed endolymphatic hydrops and unilateral juvenile deafness.

CONCLUSIONS: Patients with the contralateral type of delayed endolymphatic hydrops (DEH) may undergo an autoimmune attack against the other inner ear. As patients with unilateral juvenile deafness show no progression, despite lengthy observation, the autoantibody against the 68-kDa protein may be unrelated to the pathogenesis of DEH. OBJECTIVE: The contralateral type of DEH is believed to have an autoimmune etiology, and sometimes develops from unilateral juvenile deafness. The purpose of this study was to determine whether autoantibodies are pathogenetically important in DEH. MATERIAL AND METHODS: Sera from 9 patients with DEH, 18 patients with profound unilateral juvenile hearing loss and 15 control volunteer without inner ear diseases were investigated by means of Western blot assay against rat inner ear proteins. RESULTS: Among 8 patients with the contralateral type of DEH, 6 (75%) showed at least 1 reactive band on Western blotting. The protein that reacted most frequently had a molecular weight of 28 kDa, which was consistent with our previous results. Among 18 patients with unilateral juvenile deafness, 5 (28%) showed reactive bands, exclusively at 68 kDa.

Interferon-gamma expression in the inner ear of rats following secondary immune reaction in the endolymphatic sac.

Recently, we demonstrated increased intercellular adhesion molecule-1 (ICAM-1) expression in the inner ear of systemically pre-sensitized rats after antigen [keyhole limpet hemocyanin (KLH)] challenge into the endolymphatic sac (ES), in good correlation with the cellular infiltration. Interferon-gamma (IFN-gamma) is an important cytokine that upregulates the expression of ICAM-1. Here, we report upregulation of IFN-gamma expression in the inner ear of systemically pre-sensitized rats after antigen (KLH) challenge into the ES. Immunoreactivity for IFN-gamma was detected in the spiral ligament, suprastrial region, spiral modiolar veins, spiral collecting venules, surface membrane of the perilymphatic compartment and perilymphatic space of immunized, but not control, rats. IFN-gamma expression was detected at 1.5 h post-challenge, peaked at 6 h and gradually returned to baseline levels after 7 days. Interestingly, the time kinetics of IFN-gamma expression were in good correlation with those of ICAM-1. These observations demonstrate that antigen challenge into the ES induces IFN-gamma expression, which can then upregulate ICAM-1 expression and induce cell infiltration, suggesting that IFN-gamma may play a crucial role in immune-mediated inner ear diseases.

Immunological responses in acute low-tone sensorineural hearing loss and Ménière's disease.

OBJECTIVE: The autoimmune response appears to play an important role in some types of acute sensorineural hearing loss. Endolymphatic hydrops associated with fluctuating hearing loss has also been suggested to be caused by an immunological mechanism. Acute low-tone hearing loss (ALHL) associated with Ménière's disease (MD) is characterized by fluctuating hearing loss, and its etiology is thought to involve endolymphatic hydrops. The aim of this study was to attempt to determine the etiology of ALHL in MD. MATERIAL AND METHODS: A flow cytometer was used to analyze intracellular cytokine levels in peripheral blood from 19 patients with ALHL and 26 patients with MD and the data compared to those obtained from age- and gender-matched healthy volunteers. RESULTS: The patients with ALHL showed significantly increased levels of Th1 subsets (interferon-gamma-producing helper T cells) as compared to those in normal controls. The levels of Th2 (IL-4-producing helper T cells) subsets did not differ from those in the control group and thus Th1 predominated in ALHL patients. The patients with MD showed significantly increased natural killer cell activity but no Th1 dominance. These patients had no obvious systemic or local disease except in the inner ear. CONCLUSION: An abnormality of the Th1/Th2 balance in ALHL and increased natural killer cell activity in MD are thought to relate to inner ear disorder. These results are consistent with the possibility that the etiology of ALHL and MD involves an immune response.

Expression of caspase-activated deoxyribonuclease (CAD) and caspase 3 (CPP32) in the hydropic cochlea of guinea pigs - second report.

Apoptosis was induced in the cochlea by the injection of keyhole limpet hemocyanin (KLH) into the endolymphatic sac of guinea pigs and immunohistochemically examined. Keyhole limpet hemocyanin was injected into the right endolymphatic sac. The temporal bones were fixed via cardiac infusion of fixative and immunohistochemically stained for caspase-activated deoxyribonuclease or caspase 3. Endolymphatic hydrops became evident in the cochlea 1 day after the injection of keyhole limpet hemocyanin (n=6). The temporal bones in the control group did not show any caspase-activated deoxyribonuclease or caspase 3 immunoreactivity (n=6). Immunoreactivity for caspase 3 was detected in the supporting cells of the organ of Corti, the stria vascularis and the spiral ganglion cells. Caspase-activated deoxyribonuclease was also detected in the same areas. These findings suggest that apoptosis is involved in the pathogenesis of endolymphatic hydrops. This phenomenon could lead to cochlear dysfunction, as seen in endolymphatic hydrops.

Apoptosis in the hydropic cochlea of guinea pigs following immune reaction of the endolymphatic sac: immunohistochemical analysis.

Apoptotic change in the cochlea was studied by immunohistochemistry after the injection of keyhole limpet haemocyanin (KLH) into the right endolymphatic sac of guinea pigs. Apoptosis was examined with the specific antibody to single-stranded DNA (ssDNA). Endolymphatic hydrops became evident in the cochlea 1 day after the injection of KLH (n = 6). Increased ssDNA expression could be detected in the spiral ligament and the stria vascularis. The temporal bones in the control group did not show any ssDNA immunoreactivity (n = 6). Apoptosis is the process of the cell death. Our findings imply that apoptotic changes are involved in endolymphatic hydrops. These phenomena could lead to cochlear dysfunction as seen in endolymphatic hydrops.

Detection of single-stranded DNA in the hydropic vestibule after the direct injection of antigen into the endolymphatic sac of guinea pigs.

Immunohistochemical study for single-stranded DNA (ssDNA) with vestibule of guinea pigs was performed after the injection of keyhole limpet hemocyanin (KLH) into the right endolymphatic sac. Endolymphatic hydrops became evident by expansion of the Reissner's membrane in the cochlea of all animals 1 day after the injection of KLH. Increased ssDNA expression was detected in the sensory epithelium and transitional area, while temporal bones in the control group did not show any ssDNA immunoreactivities. ssDNA is accompanied with the apoptotic change in the vestibule. Our results suggest that apoptotic changes could be involved in the hydropic vestibule and these phenomena lead inner ear disturbance as seen in endolymphatic hydrops.

Experimental autoimmune inner ear disease: an electrocochleographic and histophysiologic study.

Systemic immunization with swine inner ear antigens in complete Freund's adjuvant induces functional disturbances in the cochlea. Morphometric data indicate that an endolymphatic hydrops develops within 2 weeks. It diminishes 6 weeks after immunization. A progressive decrease in the compound action potential amplitude is observed from 2 to 6 weeks after immunization. Enhancement of the amplitude of the summating potential is present without a clear overall correlation to the presence of endolymphatic hydrops. The amplitude of the cochlear microphonics shows no significant changes after immunization. Western blot analysis of the sera performed 2 and 6 weeks after immunization shows enhanced reactivity at 68, 50, 45, and 27 kd molecular weights, as compared to controls. The same spectrum of cross-reacting antibodies is believed to be instrumental in immune-mediated sensorineural hearing loss in patients. Apparently, cross-reacting antibodies and released mediators disturb cochlear homeostasis, resulting in the observed changes in the electrophysiological responses. However, these changes are not clearly related to structural changes at the light and electron microscopic levels.

Immune-mediated sensorineural hearing loss.

A review is given on the way our knowledge of pathways of immune responses inside and in the immediate vicinity of the inner ear has gradually developed over the past two decades. Immune reactivity plays a more important role in the etiopathogenesis and natural course of various inner ear disorders than was thought originally. They comprise certain forms of fluctuating or rapidly progressive sensorineural hearing loss (SNHL) with or without endolymphatic hydrops. Patients may present themselves clinically with symptoms resembling Ménière's disease or even with sudden deafness. Immune-mediated audio-vestibular dysfunctioning is either a separate disease entity or part of a more generalized (auto-) immune process. The various attempts which have been made to develop methods or tests to confirm the diagnosis of immune-mediated SNHL are critically reviewed, including the treatment responses to immunosuppressive therapy. Various animal models are furthermore presented.

Intercellular adhesion molecule-1 expression in the inner ear of rats following secondary immune reaction in the endolymphatic sac.

An immunological aetiology for inner ear diseases has long been proposed. The endolymphatic sac (ES) is the only immunoprivileged site in the inner ear with a resident population of immunocompetent cells. By keyhole limpet hemocyanin (KLH) challenge into the ES of systemically pre-immunized guinea pigs, we previously demonstrated an infiltration of inflammatory cells into the perilymphatic space of the cochlea. In order to understand the mechanisms involved in the recruitment of immunocompetent cells into the inner ear, and their relation to the development of endolymphatic hydrops (EH), we investigated the expression and time-kinetics of intercellular adhesion molecule 1 (ICAM-1) in the inner ear of systemically pre-immunized rats after antigen (KLH) challenge into the ES, its relation to cell infiltration in the cochlea and subsequent development of EH. By immunohistochemistry, strong ICAM-1 expression was detected in the spiral ligament, suprastrial region, spiral prominence, spiral modiolar veins, spiral collecting venules, surface membrane of the perilymphatic compartment, perilymphatic space and ES of immunized rats, but not of control rats. ICAM-1 expression was detected at 5-6 h, peaked at 10-15 h, and gradually reduced by 2 weeks. Cell infiltration into the cochlea started at 6-12 h and peaked at day one. By 6 h, 50% of challenged rats developed EH. This figure rose to 70% at 12 h, and then gradually reduced. However, immunoreactivity for KLH (antigen) was only detected in the ES. These results emphasize that the sac is the central immunological organ of the inner ear, and suggest that ICAM-1 may play a pivotal role in the aetiology of immune-mediated inner ear diseases through the recruitment of immunocompetent cells into the inner ear and subsequent development of EH.

Preliminary study of the role of endothelin-1 in the homeostasis of the inner ear.

Endothelin (ET), originally characterized as a 21-residue vasoconstrictor peptide from endothelial cells, has been reported to act as a local hormonal regulator of pressure, fluid, ions, and neurotransduction. Our previous studies suggested an important role of ET-1 in the inner ear. The present study investigated the time kinetics of ET-1 in the epithelium of the endolymphatic sac (ES) of guinea pigs and its relation to the development of endolymphatic hydrops (EH) following locally mounted secondary immune reaction. In the duration between 12 h and day 1, ET-1-like activity completely disappeared from the epithelium of the ES and was associated with the accumulation of inflammatory cells in the ES and a rapid development of EH. On day 7, ET-1-like activity recovered as a consequence of the decrease of inflammatory cells and reduction of EH. These findings suggest that ET-1 may play an important role as one of the regulators maintaining the fluid balance.

The role of allergy in Meniere's disease.

There is considerable clinical and immunologic evidence for a probable role of allergy in the production of the symptoms of Meniere's disease. The endolymphatic sac is the seat of immune reactivity in the inner ear. Inhalant and food allergies have been linked with symptoms of Meniere's disease, and many of the clinical characteristics of Meniere's disease suggest an underlying autoimmune etiology. A significant percentage of patients with Meniere's disease and allergy show improvement in their symptoms of tinnitus and vertigo when receiving specific allergy therapy.

Immune-mediated sensorineural hearing loss with or without endolymphatic hydrops: a clinical and experimental approach.

Since 1979, when McCabe first described a pattern of bilateral sensorineural hearing loss (SNHL) characterized by a rapid progression over days to weeks, the postulated autoimmune basis of this disease remains unknown. Various attempts have been made to develop the best assays that will clinically confirm the diagnosis and will help identify those patients who may respond to immunosuppressive therapy. The Western blot assay has now been widely applied by different research groups. It has been suggested that antibody to the 68-kD protein is most closely associated with this disorder. Recent analyses suggest that the protein of interest is probably a heatshock protein (hsp 70) with this molecular weight. This disease pattern of rapidly progressive bilateral SNHL presents itself clinically as a different disease than endolymphatic hydrops with fluctuating SNHL, and it is most often associated with vertigo and roaring tinnitus. Meniere's disease may be also immune-mediated, but lacks an autoimmune basis. Its etiopathogenesis is different. A critical review of our own Western blot analyses from patients with either idiopathic rapidly progressive SNHL (N = 33), sudden deafness (N = 53), or other SNHL forms (N = 71) is presented. Immuno-suppressive treatment responses were evaluated. A new concept of immune-mediated endolymphatic hydrops was also further developed on the basis of recent experimental data and earlier clinical observations in order to focus on another aspect of this most intriguing inner-ear disease.

Recurrent hearing impairment and nystagmus induced by repeated antigen exposure in actively sensitized guinea pigs.

Although many studies have suggested a relation between allergy and Ménière's disease, the pathophysiology of this condition remains controversial. The aim of this study was to clarify whether an anaphylactic reaction in the inner ear can disturb hearing and equilibrium, and whether such disturbances recur in response to repeated anaphylactic reactions. Increases in audiological threshold, nystagmus, and endolymphatic hydrops were observed in response to a single exposure to antigen administered to actively sensitized guinea pigs. The increase in audiological threshold was maximal 10 h after antigen challenge (p < 0.005) and returned to the baseline level after 7 days. Nystagmus and the increase in audiological threshold induced by antigen exposure were inhibited by prior administration of pemirolast potassium (p < 0.05), an inhibitor of chemical mediator release from mast cells. A second challenge with antigen 7 days after the first also induced an increase in audiological threshold (p < 0.05) and nystagmus. These results suggest that studies of repeated antigen challenge in actively sensitized animal models may increase our understanding of the pathophysiology of Ménière's disease.

Allergic and immunologic aspects of Meniere's disease.

Meniere's disease, although idiopathic by definition, has been ascribed to a variety of causes, which more recently include autoimmune factors. Interest in the role of allergy in Meniere's disease has also increased. Studies from this institution and elsewhere provide evidence that allergy and immunologic factors play a role in Meniere's disease in at least some patients. The symptoms of Meniere's disease are thought to be produced by a sudden influx of fluid into the endolymphatic sac, producing a rupture of Reissner's membrane in the cochlea. The endolymphatic sac is capable of trapping antigen and generating its own immune response. It has a highly vascular subepithelial space containing numerous fenestrated blood vessels that are peripheral and "leaky." At least three mechanisms by which allergy may play a role in the production of fluid in the endolymphatic sac are described: the endolymphatic sac itself might be a "target organ" of mediator released from systemic inhalant or food reactions; deposition of circulating immune complex may produce inflammation and interfere with the sac's filtering capability; and a predisposing viral infection in childhood that produces a mild impairment of endolymphatic sac function may interact with allergies in adulthood and cause the endolymphatic sac to decompensate, resulting in endolymphatic hydrops. The endolymphatic sac is the seat of immune reactivity in the inner ear. Repeated inflammatory reactions can produce sac dysfunction and eventual production of Meniere's disease.

Sensorineural hearing loss of suspected autoimmune etiology: a report of three cases.

The present paper reports three cases of sensorineural hearing loss of suspected autoimmune origin. Cases 1 and 2 were bilateral sensorineural hearing loss which responded to steroid therapy. Case 3 was bilateral fluctuant sensorineural hearing loss in conjunction with systemic lupus erythematosus. The pathogenesis of autoimmune sensorineural hearing loss is not yet fully understood. In two patients, hearing levels improved or stabilized following the use of osmotic expanders. The clinical results suggest that endolymphatic hydrops may participate in autoimmune sensorineural hearing loss.