Inner ear autoantibodies and their targets in patients with autoimmune inner ear diseases

Blood tests as biomarkers for the diagnosis and prognosis of sudden sensorineural hearing loss in adults: a systematic review

OBJECTIVE

Sudden sensorineural hearing loss is considered idiopathic in up to 90 per cent of cases. This study explored the role of blood tests as biomarkers for the diagnosis and prognosis of sudden sensorineural hearing loss.

METHOD

Two researchers filtered 34 papers into the final review. This review was pre-registered on the Prospero database and conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines.

RESULTS

Raised inflammatory markers are almost universal in sudden sensorineural hearing loss, suggesting an inflammatory or autoimmune process. The most useful biomarkers are neutrophil-lymphocyte ratio, platelet-lymphocyte ratio and fibrinogen level. Focused investigations should be deployed on a case-by-case basis to identify underlying metabolic, infective and autoimmune conditions.

CONCLUSION

A full blood count and coagulation screen (fibrinogen) is recommended in all cases of sudden sensorineural hearing loss. These are inexpensive, accessible and offer as much diagnostic and prognostic information as any other biomarker. There is emerging evidence regarding specific biomarkers for sudden sensorineural hearing loss prognosis, with heat shock protein-70, anti-endothelial cell antibody and prestin demonstrating potential; investigation of their validity through prospective, controlled research is recommended.

The relationship between serum homocysteine levels and sudden sensorineural hearing loss: a meta-analysis

OBJECTIVE

There was disagreement over the association between serum/plasma homocysteine (HCY) levels and sudden sensorineural hearing loss (SSNHL). Through the use of a meta-analysis, this study aims to determine whether there is a significant difference in serum homocysteine levels between the SSNHL group and the control group.

DESIGN

The Cochrane Library, EMBASE, and PubMed databases were all thoroughly searched. The two independent reviewers thoroughly examined the initially searched articles. The data results were calculated by standard mean difference (SMD) or odds ratios (OR). Review Manager (version 5.3) was applied to statistical data.

STUDY SAMPLE

There were 766 participants in the 6 trials with continuous outcomes that were part of the meta-analysis A. In addition, meta-analysis B, which included 961 people, contained a total of 3 studies with dichotomous results.

RESULTS

Both meta-analyses revealed the same conclusion that serum/plasma HCY levels in the SSNHL patients are higher than those in the controls (SMD 0.41, 95 % confidence interval (CI) 0.11 to 0.72, P < 0.01; OR 3.27, 95 % CI 2.16 to 4.94, P < 0.01).

CONCLUSION

This study demonstrated that the SSNHL patients' serum/plasma HCY levels were greater than those of the control group.

Allergy, Immunotherapy, and Alternative Treatments for Dizziness

Allergic reactions may result in central symptoms of dizziness, including nonspecific chronic imbalance, Meniere's disease, and autoimmune inner ear disease. Excepting first-generation antihistamines, and short-term use of steroids, most pharmacotherapies used to treat allergic rhinitis have limited benefit in treating allergically induced or related dizziness. Allergy immunotherapy and/or an elimination diet for diagnosed food allergies have been found to be effective treatments. Individuals diagnosed with autoimmune inner ear disease remain challenging to treat and may require high-dose, long-term steroid treatment, biologics, or immunomodulators for symptom control.

Pediatric Autoimmune Inner Ear Disease: A Rare, But Treatable Condition

Autoimmune inner ear disease (AIED) is a rare, but treatable cause of sudden sensorineural hearing loss in children. Most cases present acutely and involve both ears. The precise mechanism of hearing loss in AIED is not known. Many suspected etiologies have been proposed including infections, vascular abnormalities, and trauma. However, 70% of cases are defined as idiopathic. There are no standardized diagnostic criteria for AIED, and the diagnostic process may be challenging. Positive auto antibodies and response to immunosuppressive therapy support the diagnosis. Treatment may include corticosteroids and steroid-sparing immunosuppressive medications. A high index of suspicion is recommended as the hearing loss may be stabilized or even reversed with early treatment. Long-term medical treatment failures generally have good outcomes with cochlear implantation. [Pediatr Ann. 2019;48(10):e391-e394.].

Cochlear involvement in patients with systemic autoimmune rheumatic diseases: a clinical and laboratory comparative study

PURPOSE

Inner ear involvement has been reported in systemic rheumatic disease while detection of cochlin-specific antibodies has been reported in patients with idiopatic sensorineural hearing loss, suggesting cochlin's strong link to autoimmune hearing loss. The aim of this cross-sectional study was to calculate the prevalence of sensorineural hearing loss (SNHL) in patients with systemic rheumatic diseases, and to investigate any potential correlation with human antibodies to cochlin.

METHODS

Patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjogren's syndrome (SS) and systemic sclerosis (SSc) according to the criteria of American College of Rheumatology were included in the study. All patients underwent a complete ear-nose-throat physical examination and audiological evaluation with pure tone audiometry and impedance audiometry. Pure tone average was calculated, taking as a starting point the hearing loss in dB according to the recommendation 02/1 of "Bureau International d' Audiophonologie" (BIAP) so as an average hearing threshold value. Sera of all patients were tested for the presence of IgG antibodies to human cochline (COCH-IgG). Sex and age-matched healthy subjects were included as controls to each group.

RESULTS

A total of 133 patients were studied; 60 with RA, 41 with SLE, 24 with SS and 8 with SSc. 61.4% of patients reported vertigo, 41% hyperacousis, 39% hearing loss, 38% tinnitus, 37.9% headache and 2.1% sensation of ear pressure with unremarkable otoscopy. The prevalence of SNHL calculated for patients affected by RA, SLE, SS and SSc was 66.6%, 31.71%, 54.17%, and 75% respectively. The calculated average hearing thresholds value in RA was increased in comparison to SLE (p < 0.05). In addition it was also higher in patients with RA and secondary SS, in comparison to RA patients (p > 0.05). There was statistically significant correlation of average hearing threshold with disease activity score 28 (DAS28) in RA, but no correlation observed with disease activity index (SLEDAI) in SLE. COCH-IgG antibodies were detected in only two samples. The results were compared with those of their respective sex and age-matched healthy subjects.

CONCLUSION

Our study revealed increased prevalence of SNHL in patients with systemic autoimmune rheumatic disease but no correlation of hearing loss with COCHIgG antibodies. The mechanism of inner ear damage remains unknown; thus, additional prospective studies will be needed to elucidate its pathogenesis.

The clinical value of a thorough diagnostic evaluation for neurotologic complaints

PURPOSE

Determine the clinical efficacy of comprehensive neurotologic testing in patients presenting with complaints of hearing loss, tinnitus and/or dizziness.

METHODS

This is a retrospective analysis of 1170 consecutive charts of patients who presented between 1980 and 2013 with neurotologic complaints. Demographic data, chief complaint, diagnostic imaging, audiograms, and blood tests were evaluated.

RESULTS

Retrospective analysis of 1170 patient charts was performed. 762/1170 (65%) patients presented with subjective hearing loss, 575/1170 (49%) with dizziness, and 657/1170 (56%) with tinnitus. Audiometric testing revealed hearing loss in 1059/1169 (91%) patients. 536/1120 (48%) patients had abnormalities on Magnetic Resonance Imaging, and 343/1087 (32%) on Computed Tomography imaging. Endocrine and immunologic testing revealed 108/1135 (9.5%) patients were hyperglycemic; 125/1124 (11%) patients had elevated TSH; 149/1141 (13%) patients had a positive ANA; and 82/1133 (7.2%) patients were positive for RF. 198/1083 (18%) of patients were positive for HLA-B35, 246/1083 (23%) for HLA-Cw4, 454/1083 (42%) for HLA-Cw7, and 747/1060 (70%) of patients had absent HLA-DR4. 112/1085 (10%) of patients were positive for anti-68kD antibodies and 154/936 (17%) for protein 0. Many patients were diagnosed with previously unrecognized medical conditions.

CONCLUSION

Comprehensive neurotological workup results in diagnoses that would go unrecognized otherwise, allowing patients to receive prompt treatment for medically important conditions, some of which may be causally related to their neurotologic complaints. However, the value of each study for routine testing of patients with neurotologic complaints remains controversial; and the evidence presented herein should help practitioners determine what studies should be included in their patient assessments.

Prestin autoantibodies screening in idiopathic sudden sensorineural hearing loss

OBJECTIVES

To define the clinical association of serum prestin autoantibodies and their impact on prognosis, as specific serum diagnostic markers in patients with idiopathic sudden sensorineural hearing loss (ISSNHL).

DESIGN

Sera from 63 patients with ISSNHL were screened prospectively for the presence of prestin autoantibodies by an enzyme-linked immunosorbent assay (Elisa) test. Serum was assayed for anti-prestin IgG antibodies using recombinant human prestin (SLC26 A5). Demographic, clinical, and audiometric variables were analyzed.

RESULTS

Two patients (3.17%) had demonstrable anti-prestin antibodies in serum (exact 95% CI: -1.16% to 7.5%). No statistically significant association was found between prestin autoantibodies and demographic or audiologic parameters.

CONCLUSIONS

This preliminary and novel study does not support the presence of an active humoral immune reaction against prestin in ISSNHL.

Alteraciones auditivas en artritis reumatoide, lupus eritematoso sistémico y síndrome de Sjögren

Introducción. En la actualidad no hay cifras sobre las personas que padecen artritis reumatoide (AR), lupus eritematoso sistémico (LES) o síndrome de Sjögren (SS) ni información sobre las alteraciones auditivas que puede causar el tratamiento farmacológico utilizado para controlar dichas enfermedades.Objetivo. Evidenciar las posibles afectaciones y alteraciones audiológicas y vestibulares producidas por AR, LES y SS o su tratamiento farmacológico.Materiales y métodos. Se analizaron los hallazgos clínicos de herramientas diagnósticas y procedimientos de prevención e intervención de alteraciones auditivas en artículos de investigación publicados en español, inglés, francés y portugués en bases de datos científicas entre los años 2000 y 2016.Resultados. Se extrajeron 62 artículos de investigación (31 de AR, 5 de LES, 12 de SS, 5 de Hipoacusia inmunomediada, 9 de medicamentos ototóxicos), 1 tesis doctoral sobre AR, 1 tesis doctoral sobre AR y LES y 1 guía de práctica clínica para la detección temprana, diagnóstico y tratamiento de AR. Se evidenció que las pérdidas auditivas con mayor reporte son hipoacusia neurosensorial, lesiones en cadena osicular y vestíbulo-coclear.Conclusiones. Se confirmó la relación entre las lesiones audiológicas y AR, LES y SS, pero aun no es claro el desarrollo de los ototóxicos.

[The etiopathogenetic aspects of idiopathic sensorineural impairment of hearing]

The objectives of the present work were the overview of the results of the modern investigations concerning etiology of idiopathic sensorineural impairment of hearing as well as the analysis of the theory of microthrombus formation and its role in pathogenesis of hearing impairment.

Current understanding of the pathogenesis of autoimmune inner ear disease: a review

BACKGROUND

Autoimmune inner ear disease (AIED) is a poorly understood form of sensorineural hearing loss that causes bilateral, asymmetric, progressive hearing loss, sometimes with vestibular symptoms, often associated with a systemic autoimmune disease, which is noteworthy as the only sensorineural loss responsive to medical therapy. Despite much research interest of the past 25 years, its aetiopathogenesis is still unproven.

OBJECTIVE OF REVIEW

To succinctly consolidate research and opinion regarding the pathogenesis of autoimmune inner ear disease, in ongoing efforts to elucidate the molecular and intracellular pathways that lead to inner ear damage, which may identify new targets for pharmacotherapy.

TYPE OF REVIEW

Systematic review

SEARCH STRATEGY

PubMed/MEDLINE search using key terms to identify articles published between January 1980 and Apr 2014. Additionally, any landmark works discussed in this body of literature were obtained and relevant information extracted as necessary.

EVALUATION METHOD

Inclusion criterion was any information from animal or human studies with information relevant to possible aetiopathogenesis of AIED. Studies that focused on diagnosis, ameliorating symptoms or treatment, without specific information relevant to mechanisms of immune-mediated injury were excluded from this work. Articles meeting the inclusion criteria were digested and summarised.

RESULTS

A proposed pathogenic mechanism of AIED involves inflammation and immune-mediated attack of specific inner ear structures, leading to an excessive Th1 immune response with vascular changes and tissue damage in the cochlea. Studies have identified self-reactive T cells and immunoglobulins, and have variously implicated immune-complex deposition, microthrombosis and electrochemical disturbances causing impaired neurosignalling in the pathogenesis of AIED. Research has also demonstrated abnormalities in the cytokine milieu in subjects with AIED, which may prove a target for therapy in the future.

CONCLUSION

Ongoing research is needed to further elucidate the aetiopathogenesis of AIED and discern between various mechanisms of tissue injury. Large-cohort clinical studies employing IL-1 receptor blockade are warranted to determine its potential for future therapy.

Evaluation of hearing functions in patients with euthyroid Hashimoto's thyroiditis

Sensorineural hearing loss has been reported in various autoimmune diseases. The relationship between Hashimoto's thyroiditis (HT) and the auditory system has not been previously evaluated. In this study, we investigated the effect of euthyroid HT on the hearing ability of adult patients. The study included 30 patients with newly diagnosed euthyroid HT and 30 age- and gender-matched healthy controls. All subjects had a normal otoscopic examination and tympanometry, and they were negative for rheumatoid factor, antinuclear, anti-smooth muscle, antimitochondrial, antineutrophilcytoplasmic, and antigliadin antibodies. Pure tone audiometry exams at 250, 500, 1000, 2000, 4000, 6000, and 8000 Hertz (Hz) were performed in both groups. Thyroid peroxidase antibody and thyroglobulin antibody (anti-Tg) levels were higher in HT group while TSH, free T4, free T3, plasma electrolytes, glucose, lipid profile, vitamin B12, and blood pressure measurements were similar between the two groups. Higher audiometric thresholds and a higher prevalence of hearing loss at 250, 500, and 6000 Hz were detected in the HT patients than in the healthy controls (P < 0.05). Hearing levels at 250 and 500 Hz correlated positively with anti-Tg levels (ρ = 0.650, P = 0.002; ρ = 0.719, P < 0.001, respectively), and this association remained significant in linear regression analysis. Anti-Tg-positive HT patients had higher hearing thresholds at 250 and 500 Hz than anti-Tg-negative HT patients. Hearing thresholds were similar between anti-Tg-negative HT patients and the control subjects. This study demonstrated that hearing functions are impaired in HT patients. Thyroid autoimmunity seems to have an important impact on a decreased hearing ability, particularly at lower frequencies, in this population of patients.

Behçet disease as a cause of hearing loss: A prospective, placebo-controlled study of 29 patients

We conducted a prospective, placebo-controlled study to determine the incidence and severity of inner ear involvement and hearing loss in patients with Behçet disease. Our study population was made up of 29 patients with Behçet disease and 28 healthy controls. Audiometric pure-tone thresholds and transient evoked otoacoustic emission (TEOAE) levels were determined in both groups. The main outcome measures were pure-tone audiometry (PTA) levels and TEOAE levels in the two groups. PTA detected a sensorineural hearing loss in 10 of the 29 patients (34.5%). The difference in audiometric findings between the two groups was statistically significant at 1, 2, 4, and 8 kHz (p ≤ 0.0498). A comparison of TEOAE levels revealed that the difference in sound-to-noise ratio between the two groups was not significant at 1, 1.5, 2, and 3 kHz, but it was significant in 4 kHz (p = 0.02), and the difference in reproducibility between the two groups was significant at 2 and 4 kHz (p ≤ 0.03). We conclude that all patients with Behçet disease should be screened for hearing impairment and subsequently treated if an impairment is discovered.

Temporal bone histopathology and immunoglobulin deposition in Sjogren's syndrome

HYPOTHESIS

The histopathology of Sjogren's syndrome (SS) in the human inner ear correlates with mouse models of autoimmune inner ear disease.

BACKGROUND

SS is an autoimmune disease in which 25% of patients have sensorineural hearing loss (SNHL). The inner ear histology in a SS mouse model has shown degeneration of the stria vascularis (SV) and immunoglobulin G deposition on the basement membrane of SV blood vessels. Correlation with human temporal bone histopathology has not been addressed.

METHODS

The histopathology and immunohistochemistry of the inner ear in 4 patients with SS is described and compared with SS mouse models.

RESULTS

The histopathology of the inner ear in 3 patients with SS and SNHL showed severe loss of the intermediate cells of the SV and immunoglobulin G deposition on the basement membrane of SV blood vessels. These results parallel those of known SS mouse models. Additionally, there was shrinkage of the spiral ganglia neurons in 2 patients, whereas vestibular ganglia neurons were preserved. The fourth patient with SS and normal hearing showed only mild SV atrophy.

CONCLUSION

This is the first study describing the pathologic changes in the inner ear of 4 patients with SS. The 3 SS specimens with SNHL showed pathologic changes in the SV similar to the mouse model of autoimmune inner ear disease. Additionally, we propose that spiral ganglia neurons may be directly affected by SS pathology. These results highlight the importance of correlating the histopathology of human temporal bones with animal models to better understand inner ear disease in future research.

Methylenetetrahydrofolate reductase C677T gene mutation as risk factor for sudden sensorineural hearing loss: association with plasma homocysteine, folate and cholesterol concentrations

Objective:

Impaired cochlear perfusion appears to be the most important event in the development of sudden sensorineural hearing loss. Methylenetetrahydrofolate reductase gene mutations at nucleotide 677 cause reduced methylenetetrahydrofolate reductase enzyme activity, resulting in vascular impairment.

Methods:

Thirty-three patients and 68 control subjects underwent audiological and haematological investigation.

Results:

No statistically significant association was found between sudden sensorineural hearing loss and the methylenetetrahydrofolate reductase C677T gene mutation. Mean homocysteine and cholesterol concentrations were significantly higher in patients than in controls. Mean folate levels were significantly lower in patients than in controls. Amongst patients with sudden sensorineural hearing loss, no significant differences in mean cholesterol, homocysteine or folate concentration were found, comparing patients with methylenetetrahydrofolate reductase C677T mutation genotypes with those without.

Conclusion:

No statistically significant association was found between the methylenetetrahydrofolate reductase C677T gene mutation and sudden sensorineural hearing loss. There was a statistically significant difference between the homocysteine, folate and cholesterol concentrations of sudden sensorineural hearing loss patients, compared with controls. However, there was no statistically significant difference in these levels, comparing patients with and without the methylenetetrahydrofolate reductase C677T mutation.

Sudden deafness: is it viral?

A number of theories have been proposed to explain the etiopathogenesis of idiopathic sudden sensorineural hearing loss (ISSHL), including viral infection, vascular occlusion, breaks of labyrinthine membranes, immune-mediated mechanisms and abnormal cellular stress responses within the cochlea. In the present paper, we provide a critical review of the viral hypothesis of ISSHL. The evidence reviewed includes published reports of epidemiological and serological studies, clinical observations and results of antiviral therapy, morphological and histopathological studies, as well as results of animal experiments. The published evidence does not satisfy the majority of the Henle-Koch postulates for viral causation of an infectious disease. Possible explanations as to why these postulates remain unfulfilled are reviewed, and future studies that may provide more insight are described. We also discuss other mechanisms that have been postulated to explain ISSHL. Our review indicates that vascular occlusion, labyrinthine membrane breaks and immune-mediated mechanisms are unlikely to be common causes of ISSHL. Finally, we review our recently proposed theory that abnormal cellular stress responses within the cochlea may be responsible for ISSHL.

Coeliac disease and hearing loss: preliminary data on a new possible association

OBJECTIVE

Coeliac disease (CD), an autoimmune gluten-dependent enteropathy, can be associated with several extra-intestinal manifestations, including neurological disorders. At present, no data are available on the presence of hearing loss disorder in coeliac patients. The aim of the present study was to investigate the prevalence of hearing loss in coeliac patients compared with that in healthy controls.

MATERIAL AND METHODS

Twenty-four adult coeliac patients and 24 healthy subjects matched for gender, age, smoking and drinking habits were enrolled in the study. Among the coeliac patients, 6 were newly diagnosed and 18 patients were on a gluten-free diet for at least one year.

RESULTS

A hearing loss was found in 10 (47.1%) coeliac patients and 2 (9.1%) healthy controls. All CD patients with hearing loss presented a sensorineural hearing loss. The prevalence of hearing loss was significantly higher in coeliac patients than in healthy controls (p = 0.01) but it was not significantly different between untreated (33.3%) and treated (44.4%) coeliac patients (p: NS).

CONCLUSIONS

Despite the low number of subjects evaluated, the present study showed a higher prevalence of hearing loss in coeliac patients than in healthy controls, suggesting an association between CD and hearing loss. Immunological processes such as ear-specific and non-specific autoantibodies and vasculitis could be the basis of this association. Further longitudinal investigations on a larger sample size will be necessary to confirm the present data.

Identification of novel citrullinated autoantigens of synovium in rheumatoid arthritis using a proteomic approach

Recently, autoantibodies to some citrullinated autoantigens have been reported to be specific for rheumatoid arthritis (RA). However, an entire profile of and autoimmunity of the citrullinated proteins have been poorly understood. To understand the profile, we examined citrullinated autoantigens by a proteomic approach and further investigated the significance of citrullination in antigenicity of one of the autoantigens. Specifically, we detected citrullinated autoantigens in synovial tissue of a patient with RA by two-dimensional electrophoresis and Western blotting by using pooled sera from five patients with RA and anti-citrulline antibodies. After identifying the detected autoantigens by mass spectrometry, we investigated the contribution of citrullination to autoantigenicity by using a recombinant protein with or without citrullination on one of the identified novel citrullinated autoantigens. As a result, we found 51 citrullinated protein spots. Thirty (58.8%) of these spots were autoantigenic. We identified 13 out of the 30 detected citrullinated autoantigenic proteins. They contained three fibrinogen derivatives and several novel citrullinated autoantigens (for example, asporin and F-actin capping protein α-1 subunit [CapZα-1]). We further analyzed the contribution of citrullination to autoantigenicity in one of the detected citrullinated autoantigens, CapZα-1. As a result, frequencies of autoantibodies to non-citrullinated CapZα-1 were 36.7% in the RA group tested, 10.7% in the osteoarthritis (OA) group, and 6.5% in healthy donors. On the other hand, those to citrullinated CapZα-1 were 53.3% in the RA group, 7.1% in the OA group, and 6.5% in the healthy donors. This shows that autoantigenicity of citrullinated or non-citrullinated CapZα-1 is relevant to RA. The antibody titers to the citrullinated CapZα-1 were significantly higher than those to the non-citrullinated CapZα-1 in 36.7% of patients; however, the other patients showed almost equal antibody titers to both citrullinated and non-citrullinated CapZα-1. Therefore, the autoantibodies would target citrulline-related and/or citrulline-unrelated epitope(s) of CapZα-1. In conclusion, we report a profile of citrullinated autoantigens for the first time. Even though citrullination is closely related to autoantigenicity, citrullination would not always produce autoantigenicity in RA. Citrullinated and non-citrullinated autoantigens/autoepitopes would have different pathological roles in RA.

Antibody reactivity to heat shock protein 70 and inner ear-specific proteins in patients with idiopathic sensorineural hearing loss

Deafness is attributable to autoimmunity in a subset of adult patients with sensorineural hearing loss (SNHL) of unknown aetiology. To determine the roles of self-antigens in the pathogenesis of idiopathic SNHL, we analysed antibody responses to the inner ear-specific proteins, cochlin and beta-tectorin as well as the non-specific heat shock protein 70 (HSP70). Recombinant cochlin and beta-tectorin proteins were used in a qualitative Western blot assay for the detection of antigen-specific IgG antibodies in 58 patients with idiopathic SNHL and 28 healthy blood donors. In the same study cohort, we also used a Western blot assay to assess IgG antibody responses to the recombinant human HSP70. Of the 58 patient samples analysed, 19 tested positive to the HSP70, eight to cochlin and one to beta-tectorin, giving a prevalence of 33, 14 and 2%, respectively. Only one patient sample was reactive for HSP70, cochlin and beta-tectorin, seven of the remaining eight cochlin IgG antibody-positive samples were monospecific. Thus, cochlin-specific antibodies were observed predominantly in HSP70 IgG-negative patients demonstrating an additive value for testing this antibody response in patients with idiopathic SNHL.

Cochlin immunostaining of inner ear pathologic deposits and proteomic analysis in DFNA9 deafness and vestibular dysfunction

Seven missense mutations and one in-frame deletion mutation have been reported in the coagulation factor C homology (COCH) gene, causing the adult-onset, progressive sensorineural hearing loss and vestibular disorder at the DFNA9 locus. Prevalence of COCH mutations worldwide is unknown, as there is no systematic screening effort for late-onset hearing disorders; however, to date, COCH mutations have been found on four continents and the possibility of COCH playing an important role in presbycusis and disorders of imbalance has been considered. Cochlin (encoded by COCH) has also been shown as a major target antigen for autoimmune sensorineural hearing loss. In this report, we present histopathology, immunohistochemistry and proteomic analyses of inner ear tissues from post-mortem DFNA9 temporal bone samples of an individual from a large Dutch kindred segregating the P51S mutation and adult human unaffected controls, and wild-type (+/+) and Coch null (-/-) knock-out mice. DFNA9 is an inner ear disorder with a unique histopathology showing loss of cellularity and aggregation of abundant homogeneous acellular eosinophilic deposits in the cochlear and vestibular labyrinths, similar to protein aggregation in well-known neurodegenerative disorders. By immunohistochemistry on the DFNA9 temporal bone sections, we have shown cochlin staining of the characteristic cochlear and vestibular deposits, indicating aggregation of cochlin in the same structures in which it is normally expressed. Proteomic analysis identified cochlin as the most abundant protein in mouse and human cochleae. The high-level expression and stability of cochlin in the inner ear, even in the absence and severe atrophy of the fibrocytes that normally express COCH, are shown through these studies and further elucidate the pathobiologic events occurring in DFNA9 leading to hearing loss and vestibular dysfunction.

Immune-mediated inner-ear disorders in neuro-otology

PURPOSE OF REVIEW

Immune-mediated inner-ear disorders may present to different medical disciplines and new research findings emerge rapidly. The purpose of this review is to draw the different strands together to produce an overview describing the clinical presentation of immune-mediated inner-ear disorders and to discuss useful diagnostic criteria with a focus on tissue-specific and tissue-non-specific antibodies.

RECENT FINDINGS

The importance of diagnosing an immune-mediated inner-ear disorder is highlighted in the context of it being one of few forms of treatable inner-ear disorder with a good response to immunosuppressive therapy. Due to a lack of reliable tests, the criteria upon which the diagnosis of immune-mediated inner-ear disease is based are often arbitrary. Previous and current research focuses mainly on the investigation of the aetiology of immune-mediated disorders, studying the presence of autoantibodies and the antigens responsible for their production. The prognostic and therapeutic values of inner-ear-specific antibodies are still unclear. Various antigens have been suggested. However, most antigens identified have been ubiquitous proteins not specific to the inner ear and therefore lack logical association with localized inner-ear pathology.

SUMMARY

Early diagnosis of immune-mediated inner-ear disorders with prompt treatment may prevent irreversible damage to inner-ear structures. Accordingly, it is important to include immune-mediated inner-ear disorders in the differential diagnosis of patients presenting with 'idiopathic' audiovestibular dysfunction. To enable early diagnosis, we recommend that the current available routine immunological laboratory tests (antinuclear, antineutrophil cytoplasmic, antiendothelial cell, antiphospholipid/anticardiolipin and antithyroid antibodies) are used when assessing a patient with suspected immune-mediated inner-ear disorder.

Estudio de comorbilidad de la hipoacusia neurosensorial y otras enfermedades de patogenia autoinmune. Utilidad de las pruebas de laboratorio

OBJECTIVES

To value if the sensorineural hearing loss (SHL) in several autoimmune diseases (AD) is also secondary to immunomediation.

PATIENTS AND METHODS

In 342 cases with SHL and any AD and 301 normoacoustic controls with AD a non-specific immunologic battery of tests and a Western-blot (WB) for anticochlear autoantibodies were developed, and cases with SHL were treated with deflazacort.

RESULTS

Alterations in non-specific battery were similar between cases and controls. But a 12,5% of cases with SHL and a 1,6% of normoacoustic showed a positive WB (p<0,001). Steroid therapy improved hearing in 14,3% of cases. In them, sensitivity and specificity of non-specific battery were 78,4% and 75,5%, respectively, to predict response to therapy. These were 98,9% and 81,6% for WB.

CONCLUSIONS

The SHL in cases with AD can be considered immunomediated in a discrete average, but the diagnostic efficiency of WB to predict an improvement after steroid therapy is high.

Methylenetetrahydrofolate reductase gene mutations as risk factors for sudden hearing loss

Sudden hearing loss (SHL) can be caused by vascular disorders favoring impaired cochlear perfusion. Several inherited prothrombotic risk factors have been considered in the pathogenesis of vascular impairment, and the possible role of genetic alterations has recently been suggested. Methylenetetrahydrofolate reductase (MTHFR) gene mutations at nucleotides 677 and 1298 cause reduced MTHFR enzyme activity, which leads to increased homocysteine and reduced serum folate levels that are known to be involved in vascular impairment. We studied the relationship between SHL and MTHFR C677T and A1298C gene polymorphisms in 67 patients with SHL and 134 controls. Wild-type MTHFR CC677/AA1298 was significantly more frequent in the controls (P = .05), and gene mutations were significantly more frequent in the patients (P = .001; P = .001 for trend). Fifty-three patients (79.1%) and 56 controls (41.8%) (P = .012) had a double mutation (homozygosis 677TT or 1298CC; compound heterozygosis for both polymorphisms). Homocysteine levels were significantly higher and serum folate levels significantly lower in the patients than in the controls (P < .0001). These data suggest that MTHFR gene polymorphisms may be involved in the pathogenesis of SHL.

Autoimmune-Mediated Sympathetic Hearing Loss: A Case Report

BACKGROUND

Damage to one inner ear is occasionally followed by contralateral sensorineural hearing loss. This has been defined as sympathetic hearing loss.

HYPOTHESIS

It is hypothesized that autoimmunity can play a role in the pathogenesis of sympathetic hearing loss.

METHODS

A male patient who developed right-sided sympathetic hearing loss at 20 years of age, 11 years after deafness of the left ear caused by a temporal bone fracture, is described. The patient's serum was analyzed for the presence of autoantibodies against inner ear tissues by immunocytochemistry and Western blotting using rat inner ear tissues. The patient's serum was tested specifically for antibodies against heat shock protein 70 by immunodot blot. The presence of autoantibodies known to play a role in systemic autoimmune disease was also examined.

RESULTS

Immunocytochemistry on rat temporal bone sections demonstrated autoantibodies in the patient's serum specifically targeted against cochlear outer hair cells. No reactivity of the patient's serum was observed with control tissues including kidney, brain, and liver. Western blotting using homogenized rat cochlear tissues showed that the patient's serum reacted with a 25- and 27-kDa protein. No reactivity was observed with heat shock protein 70 in the immunodot blot analysis. The patient's serum did not contain autoantibodies against antinuclear antibodies, double-stranded DNA, antineutrophil cytoplasmic antibodies, basement membrane, reticulin, intestinal mucosa, muscle, collagen, or mitochondria.

CONCLUSION

Observations indicate that this patient suffered sympathetic hearing loss caused by organospecific autoimmunity directed to cochlear outer hair cells.

Antiphospholipid antibodies in patients with sensorineural hearing loss

Sensorineural hearing loss can be associated with autoimmune diseases and the presence of antiphospholipid antibodies. Sixty patients (mean age 47 years, range 18-76 years) with sudden sensorineural hearing loss were studied with audiograms, stapedial thresholds, otoacoustic emissions, positional and caloric testing. The serologic testing included antibodies against phosphatidylserine and beta(2)-glycoprotein. Additionally, a group of 34 patients (mean age 65 years, range 31-81 years) with normal tension glaucoma was examined because in a previous study these patients were reported to have elevated concentrations of antiphospholipid antibodies with a coincidence of progressive sensorineural hearing loss. The baseline for antiphospholipid antibody levels was established in a control group of 40 healthy blood donors. In 12 of the 60 patients with sudden sensorineural hearing loss, levels of antiphospholipid antibodies were elevated. Antiphosphatidylserine IgM antibodies were significantly lower compared to controls and patients with the combination of hearing loss and normal tension glaucoma (Fisher's exact two-sided test, P < 0.01). Our data suggest that antibodies against beta2-glycoprotein seem to coincidence with an acute event, such as sudden sensorineural hearing loss, whereas antibodies against phosphatidylserine IgG are detectable in the prolonged sequel, such as in patients with progressive sensorineural hearing loss and normal tension glaucoma.

Autoimmune Mouse Antibodies Recognize Multiple Antigens Proposed in Human Immune-Mediated Hearing Loss

HYPOTHESIS

Autoimmune diseased mice with hearing loss will have autoantibodies against the various cochlear antigens proposed in clinical autoimmune inner ear disease.

BACKGROUND

Serum antibodies of patients with hearing loss recognize several proteins that are proposed as possible antigenic targets in the ear. This often leads to a clinical diagnosis of autoimmune inner ear disease, although it is not clear how these antibodies cause inner ear disease. Therefore, to better understand the relationship of autoantibodies and ear disease, an examination was made of serum autoantibodies in the MRL/MpJ-Fas(lpr) autoimmune mouse with hearing loss. Similar antibody patterns in the mouse would provide an animal model in which to investigate potential autoimmune mechanisms of this clinical ear disorder.

METHODS

Sera from MRL/MpJ-Fas(lpr) autoimmune mice and normal C3H mice were tested by the enzyme-linked immunosorbent assay technique for reactivity against various reported cochlear antigens: heat shock protein 70 (bovine, human, bacterial), laminin, heparan sulfate proteoglycan, cardiolipin, and collagen types II and IV.

RESULTS

The autoimmune mouse sera showed significantly greater antibody reactivity against all of the antigens when compared with normal mouse sera.

CONCLUSIONS

Serum antibodies from autoimmune mice recognized several putative autoantigens reported for patients with hearing loss, suggesting that comparable antigen-antibody mechanisms might be operating. However, the recognition of multiple antigens did not identify any one as being the specific target in autoimmune hearing loss. The correlation of antibodies in the MRL/MpJ-Fas(lpr) autoimmune mouse and human studies indicates this animal model should aid further investigations into potential cochlear antigens in autoimmune hearing loss.

Platelet GPIaC807T polymorphism is associated with negative outcome of sudden hearing loss

To determine the relevance of inherited prothrombotic risk factors in sudden hearing loss, we investigated 85 patients with sudden hearing loss of >/= 60 dB for the presence of inherited prothrombotic risk factors. The FV G1691A, FII G20210A, GPIa C807T, GPIIIa PIA1/A2, PAI-1 4G/5G, t-PA Alu repeat ID, MTHFR C677T and CBS 844ins68 genotypes were investigated. Allele frequencies found in patients were compared to those of 85 healthy control subjects of the same ethnic background using Chi-squared and odds-ratio analysis. The frequency of the GPIa807T allele was significantly elevated in patients compared to controls. In addition, allele frequency and genotype distribution of GPIa was significantly elevated in the patient group without recovery after 3 months of sudden hearing loss onset. Allele frequencies of all other prothrombotic risk factors investigated here did not differ from those of the control subjects. The single-nucleotide polymorphism of GPIa C807T seems to play a role as a prognostic factor in recovery from sudden hearing loss.

Sudden sensorineural hearing loss: a case report supporting the immunologic theory

Sudden sensorineural hearing loss (SSNHL) is one of the autoimmune diseases of the inner ear (AIED), which is characterized by a hearing loss of above 30 decibels in at least three contiguous audiometric frequencies over a time course of 72 hours or shorter. Its cause can be found in only 10% to 15% of patients. Histopathologic findings have reported retrograde neuronal degeneration and atrophy of Corti's organ and of the vascular stria. This paper describes a case of a middle-aged female patient undergoing a treatment for hyperthyroidism who developed bilateral SSNHL. The patient was treated with methylprednisone (1 mg/kg/day) for three days with considerable hearing improvement. This treatment was followed by lung and kidney tuberculosis. The immune mechanism of this entity and the possibility of interconnected participation of the antigen type, of an autoimmune disease and of bacterial infection are discussed.

Noise-induced autoimmune sensorineural hearing loss

Typically, autoimmune sensorineural hearing loss has been described as a slowly progressive, asymmetric hearing loss that is responsive to medications traditionally used in the treatment of other autoimmune conditions. These medications include steroids and cytotoxic drugs. Inciting factors in autoimmune inner ear disease are rarely cited. We describe a case of episodic sudden hearing loss triggered consistently by environmental noise. The hearing loss was responsive to steroids at the time of each occurrence and was determined to be autoimmune. This case raises questions about the relationship between autoimmune inner ear disease and sensitivity to environmental noise that warrant further research.

Clinical associations of serum antiendothelial cell antibodies in patients with sudden sensorineural hearing loss

OBJECTIVES/HYPOTHESIS

The role of antiendothelial cell antibodies in systemic vasculitis has been reported. The aim of the study was to define the clinical associations of serum antiendothelial cell antibodies in patients with sudden sensorineural hearing loss.

STUDY DESIGN

A prospective study in patients with sudden sensorineural hearing loss.

METHODS

Serum samples were taken from 59 consecutive patients with sudden sensorineural hearing loss at time of presentation and from 28 normal control subjects. Indirect immunofluorescence assay was used to detect antiendothelial cell antibodies.

RESULTS

The prevalence of antiendothelial cell antibody detection was 54% (32 of 59 patients), with a statistically significant difference between patients and control subjects (P =.0004). Antiendothelial cell antibody positivity was significantly associated with absent recovery of hearing loss (P =.0020).

CONCLUSIONS

The cytotoxicity to endothelial cells of the inner ear by antiendothelial cell antibody-positive sera might play a role in causing the stria vascularis damage in immune-mediated sudden sensorineural deafness. The appearance of antiendothelial cell antibody is related to the poor outcome of hearing loss, and its detection could be helpful in the selection of particular patients with sensorineural hearing loss for specific immunosuppressive treatments.

Autoimmunity in sudden sensorineural hearing loss: possible role of anti-endothelial cell autoantibodies

In order to verify whether anti-endothelial cell autoantibodies (AECAs) can be used as serological markers of inner ear vasculitis in sudden sensorineural hearing loss (SSHL), 32 patients affected by idiopathic SSHL were investigated. All patients underwent a routine general physical examination and extensive audiovestibular, microbiological and immunological investigations. Fourteen normal subjects without a history of HL, autoimmune or metabolic disease served as controls. Detection of AECAs was performed using an indirect immunofluorescence technique. AECA-positive patients were treated with methylprednisone, while AECA-negative patients were treated with a combined regimen of steroids, plasma expander and aspirin. The average hearing recovery for 5 frequencies (0.25-4 kHz) was analyzed in each subject 1 month after treatment and every 3 months thereafter; median follow-up was 12 months (range 9-18 months). A total of 15/32 patients (46.8%; 11/19 females, 4/13 males) were AECA-positive and thus differed significantly from the normal population in whom only 2/14 tested cases were positive (p = 0.03). Severe hearing loss was associated with being AECA-positive in 8/11 cases. During follow-up, 25/32 patients improved their hearing and 17 of these patients were AECA-negative. The seven cases without hearing improvement were all AECA-positive. In patients with SSHL, immune-mediated vascular damage may have a pathogenetic role and AECAs may represent a serological marker of vasculitis even if they are not inner ear-specific and even if they represent an epi-phenomenon rather than the only cause of SSHL.

Hearing loss evaluation of Sjögren's syndrome using distortion product otoacoustic emissions

Sjögren's syndrome (SS) is a cell-mediated immune disorder primarily affecting the exocrine glands and hearing loss may be the first otological manifestation of this autoimmune disease. In order to assess the degree of sensorineural hearing loss in SS, 22 female patients were examined by means of standard audiometric tests (pure-tone audiometry, acoustic reflexes and impedance testing) and using distortion product otoacoustic emissions (DPOAEs). The results indicated that only 36.3% of the patients had mild sensorineural hearing loss. Hearing level and distortion product threshold estimates were found to be significantly correlated. No relationship was found between the duration of the disease and the DPOAE and hearing threshold variables. The data suggest that SS may not directly cause sensorineural hearing loss.