Anti-endothelial autoantibodies in patients with sudden hearing loss

Analysis of NFKB1 and NFKB2 gene expression in the blood of patients with sudden sensorineural hearing loss

OBJECTIVES

Sudden Sensorineural Hearing Loss (SSNHL) is an increasingly common health problem today. Although the direct mortality rate of this disorder is relatively low, its impact on quality of life is enormous; this is why accurate identification of pathogenesis and influencing factors in the disease process can play an essential role in preventing and treating the disease. Acute inflammation, which leads to chronic inflammation due to aberrant expression of inflammation-mediating genes, may play a significant role in the pathogenesis of the disease. The essential Nuclear factor kappa B (NF-kB) pathway genes, NFKB1 and NFKB2, serve as prothrombotic agents when expressed abnormally, compromising the cochlea by disrupting the endolymphatic potential and causing SSNHL.

METHODS

This study investigates the expression levels of NFKB1 and NFKB2 in peripheral blood (PB) through a quantitative polymerase chain reaction in 50 Iranian patients with SSNHL, and 50 healthy volunteers were of the same age and sex as controls.

RESULTS

As a result, NFKB2 expression levels in patients were higher than in controls, regardless of sex or age (posterior beta = 0.619, adjusted P-value = 0.016), and NFKB1 expression levels did not show significant differences between patients and controls. The expression levels of NFKB1 and NFKB2 had significantly strong positive correlations in both SSNHL patients and healthy individuals (r = 0.620, P = 0.001 and r = 0.657, P 0.001, respectively), suggesting the presence of an interconnected network.

CONCLUSION

NFKB2 has been identified as a significant inflammatory factor in the pathophysiology of SSNHL disease. Inflammation can play an essential role in developing SSNHL, and our findings could be used as a guide for future research.

The Correlation of Clinical Features and Endolymphatic Hydrops Visualized by 3D-Real IR MRI in Children With Sudden Sensorineural Hearing Loss

OBJECTIVES

To investigate the correlation between clinical features and endolymphatic hydrops (EH) in children with sudden sensorineural hearing loss (SSNHL).

METHODS

We collected 30 SSNHL children aged ≤17 years old, all of whom underwent intravenous gadolinium injection. After 4 hours, inner ear 3-dimensional inversion recovery sequence with real reconstruction (3D-real IR) magnetic resonance imaging was performed. Combined with their medical history such as gender, age, disease course, hearing loss, and so on, the results were analyzed.

RESULTS

Different degrees of EH were shown in the vestibule or different turns of cochlea in the affected ears of SSNHL children, and 12 (40%) of 30 children showed positive EH. Age, low and middle frequency hearing loss, and other clinical symptoms such as dizziness and ear fullness have been shown to be related to a certain degree of EH in vestibule or cochlea, whereas no relationship was found between EH and other clinical features such as high-frequency hearing loss, gender, affected side, and tinnitus.

CONCLUSIONS

Endolymphatic hydrops may not reflect the trend of disease progression over time in children with SSNHL, but the age of onset may be an important factor in the presence or absence of EH. Endolymphatic hydrops may be one of the causes of dizziness and ear fullness but has no obvious connection with the occurrence of tinnitus. Older SSNHL children with dizziness and ear fullness should maintain long-term follow-up to dynamically monitor the changes in EH.

The Role of Anti-Endothelial Cell Autoantibodies and Immune Response in Acute Low-Tone Hearing Loss

OBJECTIVE

Immunity is associated with acute low tone hearing loss. However, the exact pathophysiology of immunity-mediated acute low tone hearing loss remains unknown. In this study, we evaluated the presence, therapeutic effectiveness, and immunopathological mechanisms of anti-endothelial cell autoantibodies (AECEs) in patients with acute low-frequency hearing loss.

MATERIAL AND METHODS

Forty-nine patients who were treated as inpatients having acute low-frequency hearing loss and additional symptoms, such as ear fullness, tinnitus, dizziness, or hyperacusis, were enrolled in this study. Serum samples from these patients were collected for laboratory serum autoimmunity detection, including AECAs, antinuclear antibodies, immunoglobulin, and circular immune complex. Therapeutic responses to combination therapy in short-term outcome and serum cytokine levels were compared between AECA-positive and AECA-negative patients.

RESULTS

Anti-endothelial cell autoantibodies-positive patients tended to show significantly less response to standard therapy compared with AECAs controls (P < .05). Moreover, some serum cytokine levels elevated in both AECAs- and AECAs+ groups. Positive ratio of interleukin-8 and concentrations of macrophage inflammatory protein-1α were found higher in AECAs+ groups (P < .05).

CONCLUSION

The results supported that AECAs might wield influence on the short-term outcome of acute low-tone hearing loss (ALHL) treatment. Furthermore, AECA-mediated acute low-frequency hearing loss possibly involved dysregulation of inflammation process and release of cytokines.

Sudden Sensorineural Hearing Loss in Children: Clinical Characteristics, Etiology, Treatment Outcomes, and Prognostic Factors

OBJECTIVE

To investigate the clinical characteristics, etiology, treatment outcomes, and prognostic factors of sudden sensorineural hearing loss (SSNHL) in children to guide the clinical diagnosis and treatment of SSNHL in the pediatric population.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Patients diagnosed with SSNHL from November 2011 to December 2017 with relatively complete clinical data.

INTERVENTION

Diagnosis and systemic treatment of SSNHL.

MAIN OUTCOME MEASURES

Patients' clinical characteristics, etiology, laboratory tests, imaging, pure-tone audiometry at admission, and discharge were analyzed.

RESULTS

A total of 25 children and 149 adults with SSNHL were included. Recent or previous viral infection rates (81.8%) and fasting blood glucose level (5.23 + 1.47 mmol/L) in children with SSNHL were lower than those in adult SSNHL patients (p = 0.033, p = 0.033). Autoimmune abnormalities (90.0%) and plasma fibrinogen abnormalities (27.3%) were higher in children with SSNHL than those in adult SSNHL patients (40.0%, 8.8%, respectively, p < 0.05). The recovery rate in children (38.4%) with SSNHL is comparable to that in adults (22.6%), but children have a higher complete rate compared to adults (26.9%, 11.3%, respectively, p < 0.05). Children with a profound audiometric curve had a worse prognosis in comparison to other types of audiometric curves (p = 0.041).

CONCLUSIONS

Children with SSNHL have a lower rate of viral infection in comparison to adults with SSNHL. Fasting blood glucose levels, complement C3, C4, and fibrinogen may be closely related to childhood SSNHL. The recovery rate in children with SSNHL is comparable to that in adults, but children have a higher complete rate compared to adults. A profound hearing curve is an unfavorable prognostic factor in both children and adults with SSNHL.

Early Magnetic Resonance Imaging for Patients With Idiopathic Sudden Sensorineural Hearing Loss in an Emergency Setting

OBJECTIVE

The role of magnetic resonance (MR) imaging in idiopathic sudden sensorineural hearing loss (ISSHL) is controversial due to the inhomogeneity of clinical and MR protocols. The aim of this work is to relate early MR findings obtained immediately after the admission, with the clinical presentation, the audiological findings, and the outcomes of treatment.

STUDY DESIGN

Prospective observational study.

SETTING

Tertiary referral university center.

PATIENTS

Forty-seven patients (22 M, 25 F; age: 54.4 ± 17.5 yr) consecutively referred to the Department of Emergency for ISSHL.

INTERVENTIONS

All patients underwent the diagnostic and therapeutic work-up for ISSHL, and MR imaging within 72 hours from the admission, independently of the symptoms onset. All patients received the same treatment (systemic steroid therapy, intratympanic steroid injection, and hyperbaric oxygen therapy).

MAIN OUTCOME MEASURE(S)

MR patterns, clinical, and laboratory findings.

RESULTS

MR imaging was positive in 25 of 47 cases (53%), with a perfect agreement between clinical and MR examinations (Cohen K = 1) upon the affected ear. Three different radiological patterns were observed: labyrinthine haemorrhage (n = 5), acute inflammatory process (n = 14), isolated blood-labyrinth barrier breakdown (n = 6). By binary logistic regression, only vertigo was associated with a positive MR imaging [B = 2.8; p = 0.011; OR = 9.5 (95% CI: 2.2-40.8)] and the latter was the only variable associated with an unfavorable outcome [(B = 2.8; p = 0.02 OR = 12.8 (95% CI: 2.9-56.7)].

CONCLUSION

Patients affected by ISSHL with associated vertigo show a higher likelihood of having a positive MR imaging, which, in turn, seems to predict an unfavorable outcome.

Can unilateral, progressive or sudden hearing loss be immune-mediated in origin?

OBJECTIVE

The aim of the present study was to demonstrate that the positivity of nonspecific immunological tests could be found not only in bilateral hearing loss but also in unilateral cases, either sudden or progressive.

METHOD

An observational case series study included subjects suffering from unilateral or bilateral, sudden or progressive, symmetric or asymmetric sensorineural hearing loss (SNHL). All the patients underwent pure tone audiometry and the following battery of blood exams: anti-nuclear antibody (ANA), extractable nuclear antigen (ENA) antibody screening, anti-thyroperoxidase (anti-TPO), anti-thyroglobulin and anti-smooth muscle antibody (ASMA).

RESULTS

The positivity to nonspecific immunological test was found in nearly 70% of the study groups. ASMA and ANA were found to be present in both bilateral and unilateral cases, without statistical difference. Considering the correlation between positivity/negativity and systemic autoimmune pathologies, in the bilateral forms of hearing loss, a high incidence of thyroid pathologies has been identified, with a higher percentage of systemic autoimmune diseases in respect to the normal population.

CONCLUSIONS

The nonspecific autoimmune tests are worth to be performed also when SNHL is not bilateral and progressive, since an immunological mechanism could also underlie unilateral and sudden SNHL cases.

Oral steroid regimens for idiopathic sudden sensorineural hearing loss

OBJECTIVE

To determine hearing recovery in patients with idiopathic sudden hearing loss treated with varying amounts of oral steroids.

STUDY DESIGN AND SETTING

A retrospective chart review (n = 75) in a tertiary care clinic examined sudden hearing loss patients treated with 1 60-mg prednisone taper, 1 course of steroid less than a 60-mg taper, or any 2 courses of oral steroid.

RESULTS:

Overall, 35% of the patients recovered a clinically significant amount of hearing. Recovery was associated with immediate treatment (within 2 weeks from onset), better hearing at the onset of treatment, and treatment with the higher dose of prednisone in patients with just 1 additional symptom (dizziness or tinnitus). Patients tended to continue to experience some recovery in hearing up to 4 months after treatment.

CONCLUSION:

Immediate treatment of patients with unilateral idiopathic sudden hearing loss and additional symptoms (dizziness or tinnitus) with a 14-day course of 60 mg prednisone (with taper) is recommended. EBM rating: B-3.

Pathophysiology of the cochlear intrastrial fluid-blood barrier (review)

The blood-labyrinth barrier (BLB) in the stria vascularis is a highly specialized capillary network that controls exchanges between blood and the intrastitial space in the cochlea. The barrier shields the inner ear from blood-born toxic substances and selectively passes ions, fluids, and nutrients to the cochlea, playing an essential role in the maintenance of cochlear homeostasis. Anatomically, the BLB is comprised of endothelial cells (ECs) in the strial microvasculature, elaborated tight and adherens junctions, pericytes (PCs), basement membrane (BM), and perivascular resident macrophage-like melanocytes (PVM/Ms), which together form a complex "cochlear-vascular unit" in the stria vascularis. Physical interactions between the ECs, PCs, and PVM/Ms, as well as signaling between the cells, is critical for controlling vascular permeability and providing a proper environment for hearing function. Breakdown of normal interactions between components of the BLB is seen in a wide range of pathological conditions, including genetic defects and conditions engendered by inflammation, loud sound trauma, and ageing. In this review, we will discuss prevailing views of the structure and function of the strial cochlear-vascular unit (also referred to as the "intrastrial fluid-blood barrier"). We will also discuss the disrupted homeostasis seen in a variety of hearing disorders. Therapeutic targeting of the strial barrier may offer opportunities for improvement of hearing health and amelioration of auditory disorders. This article is part of a Special Issue entitled <Annual Reviews 2016>.

Proteomics studies in inner ear disorders: pathophysiology and biomarkers

Although proteomics has been exploited in a wide range of diseases for identification of biomarkers and pathophysiological mechanisms, there are still biomedical disciplines such as otology where proteomics platforms are underused due to technical challenges and/or complex features of the disease. Thus, in the past few years, healthcare and scientific agencies have advocated the development and adoption of proteomic technologies in otological research. However, few studies have been conducted and limited literature is available in this area. Here, we present the state of the art of proteomics in otology, discussing the substantial evidence from recent experimental models and clinical studies in inner-ear conditions. We also delineate a series of critical issues including minute size of the inner ear, delicacy and poor accessibility of tissue that researchers face while undertaking otology proteomics research. Furthermore, we provide perspective to enhance the impact and lead to the clinical implementation of these proteomics-based strategies.

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.

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.

Physiopathology of the cochlear microcirculation

Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature.

Positive family history of idiopathic sudden sensorineural hearing loss

Idiopathic sudden sensorineural hearing loss (ISSNHL) is a heterogenic disease. Multiple factors influencing aetiology and prognosis are discussed. A retrospective clinical characterisation and analysis of family history of ISSNHL patients was performed to investigate influences on the disease. 186 inpatients diagnosed with ISSNHL were characterised by health records and a standardised questionnaire. Audiograms were observed. 75 controls that had never experienced an event of ISSNHL were questioned about family members being affected by ISSNHL. 63.4% of all patients could be assigned to at least one group with similar causes of ISSNHL (noise exposure, positive family history, infectious diseases, hypothyroidism and fibromuscular dysplasia). A positive family history for ISSNHL has not been reported so far. Therefore, we accentuated the characterisation of patients with positive family history. 21.4% affirmed a positive family history. In ten families, at least two family members were reported as ISSNHL patients. In comparison with patients with negative family history, they tend to be younger, experience more events of ISSNHL and show less improvement of hearing abilities under therapeutic treatment (non-significant). Differences intensified between smokers with positive family history and non-smokers with negative family history. Differences concerning average age were statistically significant (p = 0.001). Within 75 controls 11 families were reported with one member being affected by ISSNHL. In the control group we did not detect any family with more than one ISSNHL patient. The results indicated that patients with positive family history tend to have an aggravated course of ISSNHL. Further studies should help to confirm these results and to identify environmental or genetic factors leading to ISSNHL. This might support a better understanding of the aetiology of ISSNHL and offer new possibilities for prevention and therapy.

Utility of immunologic parameters in the evaluation of Meniere's disease

CONCLUSION

Because of the lack of association between a positive test and response to corticosteroid treatment, at present, detection of anti-HSP 70 antibody, tumor necrosis factor (TNF)-alpha, erythrocyte sedimentation rate (ESR), or antinuclear antibody (ANA), does not offer clinically useful information in the treatment of Meniere's disease (MD).

OBJECTIVES

The study was designed to investigate the performance of various laboratory tests, including anti-HSP 70, TNF-alpha, ESR, ANA, and anti-phospholipid antibodies, in the diagnosis and treatment response of patients with MD.

PATIENTS AND METHODS

Thirty patients who presented with MD and 30 healthy people were selected as study and control groups, respectively. The laboratory panel included the following tests: anti-HSP 70 antibody immunoassay, TNF-alpha, ESR, ANA, and anti-phospholipid antibodies. The study group was given corticosteroid therapy and separated into two groups: the corticosteroid responders and the corticosteroid non-responders. In the follow-up, repeat audiograms were evaluated to determine the response to treatment.

RESULTS

TNF-alpha was found at significantly lower titers in the study group when compared with the control group (p<0.05). Anti-HSP 70 was not found in high titers in the study group. ANA positivity in patients with MD was not statistically different from the control group. There was no significant difference in the treatment response for any of the parameters tested.

[Audiovestibular manifestations in systemic vasculitis]

Systemic vasculitides constitute a heterogeneous group of diseases with frequent overlapping in their clinical findings and the size of the vessels involved. They may be primary or secondary to other diseases. Their common characteristic is the inflammation of blood vessels, giving rise to ischaemia. In the present article, we have reviewed the most common audiovestibular features that may be observed in patients with systemic vasculitides. Audiovestibular manifestations may be the first symptom of a systemic vasculitis. Audiological manifestations include sudden hearing loss and progressive sensorineural hearing loss. Vertigo and nystagmus are vestibular symptoms that may be observed in several systemic vasculitides. Vestibular loss in caloric test, abnormal head-shaking nystagmus, head thrust test and positioning test (benign paroxysmal positioning vertigo) may also be found. Improvement of audiovestibular function is frequently observed in patients with giant cell arteritis following corticosteroid therapy.

Sudden hearing loss in chronic hepatitis C patient suffering from Turner syndrome, treated with pegylated interferon and ribavirin

Sudden hearing loss is a very rare complication of interferon-alpha treatment. At this time, hearing loss in patients treated with pegylated interferon and ribavirin has only been described in two reports. We present a case of a 27-year-old patient who was diagnosed with Turner syndrome, treated for hepatitis C with pegylated interferon and ribavirin, and suffered from hearing loss during the 10th week of treatment. Audiometric examination revealed a bilateral sensorineural hearing loss (SNHL). Auditory brainstem response (ABR) measures confirmed the diagnosis. We decided to comply with the patient's request to continue therapy, which only led to slight further deterioration of the patient's hearing ability. However, 18 months after the end of therapy a follow-up audiometric examination disclosed a bilateral SNHL.

Prevalence and clinical significance of anticardiolipin, anti-beta2-glycoprotein-1, and anti-heat shock protein-70 autoantibodies in sudden sensorineural hearing loss

Sudden sensorineural hearing loss (SSNHL) is frequently classified as 'idiopathic' since the causative factor responsible for its onset is not identified in most cases. In the present study, we determined whether SSNHL is clinically associated with serum anti-heat shock protein-70 (anti-HSP70) and antiphospholipids (anti-PLs) autoantibodies and whether these autoantibodies have an impact on the prognosis of SSNHL. Sera from 63 patients with SSNHL were screened prospectively for the presence of anti-HSP70 and anti-PLs autoantibodies by an enzyme-linked immunosorbent assay test. Anti-PLs antibodies in this study consisted of anticardiolipin, and anti-beta(2)-glycoprotein-1 antibodies. Serum was assayed for anti-HSP70 IgG antibodies using recombinant human HSP70. Demographic, clinical, and audiometric variables were analyzed to find the possible role of serum autoantibodies in SSNHL patients. Sixteen patients (25.4%) had demonstrable anti-HSP70 antibodies in serum. Twenty-one patients (33.3%) showed a positive result for at least one isotype (IgM or IgG) of anti-PLs. In 19% of the patients, anti-HSP70 and anti-PLs antibodies were positive in two combinations. A statistically significant association was found between anti-HSP70 antibodies and the Siegel recovery grade subgroup. SSNHL patients who were positive for anti-HSP70 antibodies showed a significantly higher rate of complete recovery and incomplete but partial recovery than SSNHL patients without anti-HSP70 antibodies (p = 0.0496). Statistically significant association was found between total anticardiolipin, total anti-beta(2)-glycoprotein-1, total anti-PLs, and anti-PLs in combination with anti-HSP70 antibodies and age (p = 0.0229). The detection of autoantibodies to HSP70 and PLs offers a pliable explanation for the immune-mediated mechanism of SSNHL. The present study confirms and supports previous studies regarding the association between anti-HSP70 and anti-PLs antibodies with SSNHL, and is the first to identify a positive association between anti-HSP70 antibodies and a positive outcome of SSNHL. Further studies are necessary in order to identify and further clarify the immunologic role of the presence of autoantibodies and their impact on the prognosis of SSNHL.

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.

Autoimmune Hearing Loss: Improving Diagnostic Performance

OBJECTIVES

Due to the lack of specific serological markers for the diagnosis of immune-mediated hearing loss, an exhaustive immunologic work-up study for patients is usually performed. The aim of the present study is to find the most cost-effective laboratory tests used for the diagnosis of this entity.

PATIENTS AND METHOD

Comparative study between 2 groups of patients with a high suspicion of suffering diverse clinical forms of immune-mediated hearing loss, subjected to different serologic testing designs: the classical immunologic work-up study (125 patients) in comparison with a more restricted examination analysis (57 patients), based on a high risk profile recently reported.

RESULTS

Diagnostic efficiency was similar.

CONCLUSIONS

Since financial resources are limited, ANA and immunophenotype of PBL (peripheral blood lymphocytes) are recommended for the evaluation of a patient with suspected immune-mediated hearing loss.

Pathogenic mechanisms of anti-endothelial cell antibodies (AECA): their prevalence and clinical relevance

Anti‐endothelial cell antibodies (AECA) represent a heterogeneous family of autoantibodies directed against structural endothelial proteins, as well as antigens adhering to endothelial cells. Although AECA immunoassays still show a high‐interlaboratory variability, several findings suggest a pathogenic role of these autoantibodies in diseases characterized by endothelial damage. In this chapter, we analyze the knowledge about AECA prevalence, clinical relevance, and their pathogenic role in autoimmune diseases focusing in particular on systemic lupus erythematosus, antiphospholipid syndrome, systemic sclerosis (SSc), and systemic vasculitis.

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.

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.

Immunologic work-up study for inner ear disorders: looking for a rational strategy

CONCLUSIONS

For the evaluation of a patient with suspected immune-mediated inner ear disease (IMIED), an exhaustive immunologic work-up study is not recommended if financial resources are limited. Analysis of antinuclear antibodies (ANA) and the immunophenotype of peripheral blood lymphocytes (PBL) proved to be the most useful tests in our population to support the clinical diagnosis of IMIED.

OBJECTIVE

Owing to the lack of specific serological markers for the diagnosis of IMIED, an exhaustive immunologic work-up study for patients with suspected IMIED is usually performed. The aim of this study was to estimate the use of resources and the costs involved in the routine laboratory tests used for the diagnosis of IMIED.

MATERIAL AND METHODS

This was a comparative study of two groups of patients with a high suspicion of diverse clinical forms of IMIED who were subjected to different serologic test designs. The cost of the classical immunologic work-up study used for the diagnosis of IMIED (n=125) was estimated in comparison with that of a more restricted examination, based on a recently reported high-risk profile, involving the analysis of ANA and PBL (n=57).

RESULTS

The diagnostic efficiency of the two protocols was similar. The cost of a complete immunologic work-up study was 241.77 euros and that of the limited analysis was 53.12 euros.

Sudden hearing loss and MTHFR 677C>T/1298A>C gene polymorphisms

PURPOSE

Sudden hearing loss (SHL) can be caused by vascular disorders favoring impaired cochlear perfusion. A number of inherited prothrombotic risk factors have been considered in the pathogenesis of vascular impairment and the possible role of genetic alterations has recently been suggested. We aimed to investigate the relationship between SHL and MTHFR 677 and 1298 gene polymorphisms.

METHODS

DNA genotyping was performed on peripheral blood leukocytes in 45 SHL patients and 135 controls.

RESULTS

Wild-type MTHFR (677CC/1298AA) was significantly more frequent in the controls (P=0.01), and gene polymorphisms (677CT, 677TT, 1298AC, 1298CC, compound 677CT/1298AC) were significantly more frequent in the patients (P=0.005; Ptrend=0.001).

CONCLUSION

These data suggest that MTHFR gene polymorphisms may be considered as risk factors for SHL and participate on vascular impairment related to this disorder. Further studies, based on large series of patients, are needed to definitely assess the role of this prothrombotic factor in the etiopathogenesis of SHL.

Sudden hearing loss in patients with chronic hepatitis C treated with pegylated interferon/ribavirin

BACKGROUND

Sudden hearing loss has been reported on standard interferon (IFN)-alpha2 therapy. This is the first report on the occurrence of sudden hearing loss in six cases of chronic hepatitis C in temporal relation to treatment with pegylated (PEG)-IFN alfa2a or b/ribavirin combination therapy. Three patients were treated in an ongoing randomized placebo-controlled trial comparing the addition of 200 mg amantadine or placebo to the combination of 180 microg PEG-IFN alpha2a (PEGASYS, Roche, Basel, CH)/wk and 1-1.2 g ribavirin/d (COPEGUS, Roche, Nutley, USA) in de novo patients infected with HCV genotype 1. Sudden hearing loss and tinnitus developed on day 1 and after 4, 23, 25, 36, and 40 wk of treatment, respectively.

CONCLUSIONS

Sudden hearing loss may occur in about 1% of patients on PEG-IFN/ribavirin combination therapy. This rate was not different to that observed in an untreated population. Possible mechanisms involved include direct ototoxicity of IFN, autoimmunity, and hematological changes. In contrast to published cases on auditory disability due to standard IFN, hearing loss did not fully resolve after discontinuation of therapy with PEG-IFN. On the other hand, symptoms did not worsen on continued treatment. Therefore, the decision whether to continue or to stop the treatment when signs of ototoxicity appear is based on the clinical judgment of the treating physician.

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.

Titulación de anticuerpos anticocleares mediante western-blot y grado de recuperación auditiva tras corticoterapia en pacientes con sordera súbita

OBJECTIVES

Detection of antichoclear antibodies in patients with sudden deafness (SD) ranges from five to forty one percent depending on authors. We tried to correlate the level of antibodies measured by Western-blot (WB) and hearing loss.

PATIENTS AND METHODS

Forty nine subjects bearing of SD and a positive WB for bovine cochlear antigen. Hearing loss average was measured at the onset and after treatment with deflazacort 1 mg/kg per day by means of audiometry, and antibody titles were quantified in the diluted sera.

RESULTS

Initial loss was 49.4+/-20.6%, and after corticotherapy it was 15.9+/-18.0%. There was no statistically significative correlation titles-hearing loss (y=0.1122x+30.613; R2=0.7552) nor titles-recovery (y=-0.0818x+8.,65; R2=0.3229).

CONCLUSIONS

Although predictive capability for treatment response is accepted for WB, quantifying of the antibody titles in patients with SD does not allow to make a prognosis about the average hearing recovery.

Autoimmune sensorineural hearing loss

Autoimmune sensorineural hearing loss has been increasingly recognized as a clinical entity since its description by McCabe in 1979. Recognition and proper management of this condition is important, as it is one of the very few forms of sensorineural hearing loss that can be successfully treated by medical therapy. Recent studies have provided experimental evidence to suggest that immune processes can cause sensorineural hearing loss in animals and humans. However, antigenic targets within the inner ear are diverse and as a result conclusive evidence for specific autoimmune damage to the inner ear has been elusive. This review focuses on the recent progress in understanding of the aetio-pathogenesis of autoimmune hearing loss along with a description of the various clinical conditions in which they occur. Recent advances in the laboratory diagnosis and management of this interesting condition are also described.

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.

Sudden sensorineural hearing loss: supporting the immunologic theory

Sudden deafness constitutes a diagnostic challenge. Classically, 2 causes, viral and vascular, are considered in the origin of idiopathic sudden hearing loss. More recently added to the list of possibilities are rupture of the membranous labyrinth and immune-mediated sensorineural hearing loss. The latter can be either primary and localized to the inner ear or, in perhaps fewer than one third of cases, secondary to generalized systemic autoimmune disease. The purpose of the present review is to define immune-mediated sudden sensorineural hearing loss as a distinctive entity, on the basis of clinical, immunologic, and pathological findings, and suggest a profile of the typical patient.

Prognostic factors of sudden hearing loss in children

OBJECTIVE

Sudden hearing loss in children under 15 years old is rare and its pathophysiology remains unclear. The aim of this retrospective study was to define prognostic factors of sudden hearing loss in children under 15 years old.

METHODS

Among the patients referred to our institution during the period 1990-1999 for sudden hearing loss, 12 children were considered eligible for this study (mean age=9.5 years old). Patients were divided into three groups according to hearing recovery and seven putative prognostic factors were analyzed.

RESULTS

Total hearing recovery (group I: 90-100%) occurred in 28.5% of cases, partial hearing recovery (group II: 11-89%) occurred in 28.5% of cases and absence of recovery (group III: 0-10%) was reported in 43% of cases. Factors such as age, sex, and bilaterality of hearing loss were not correlated with hearing recovery.

CONCLUSIONS

Initial severe hearing loss, associated vertigo and 'downward' audiometric curve were three negative prognostic factors of hearing recovery. Tinnitus has only been reported in children with partial or total hearing recovery.

Autoimmune vestibulo-cochlear disorders

Autoimmune vestibulo-cochlear disorders (AVCD) represent a group of syndromes with overlapping clinical features, manifesting as sensorineural hearing loss, often associated with vertigo, tinnitus, and aural fullness, and believed to be caused by an autoimmune mechanism. Although definitive evidence of a classic "autoimmune process" is still lacking, substantial indirect evidence has accumulated to strongly indicate such a pathogenesis. Rapidly progressing AVCD is analogous to rapidly progressive glomerulonephritis in that inner ear inflammation progresses to severe, irreversible damage within 3 months of onset (and often much more quickly). Thus patients with rapidly progressive AVCD are treated with a sense of urgency. Prompt treatment with corticosteroids and other antirheumatic/immunosuppressive agents can preserve hearing and vestibular functions. We are not aware of any randomized controlled clinical trials evaluating the efficacy of antirheumatic/immunosuppressive agents in AVCD. In this article we review reports of various therapies that have been tried in this condition and our experience of etanercept therapy in AVCD.

Autoimmune inner ear disorders

There is considerable evidence to suggest that hearing and vestibular function can be influenced by autoimmune processes. A number of systemic autoimmune disorders include hearing loss and vertigo as part of their constellation of symptoms. Although classic evidence for a specific autoimmune etiology mediated by immune response directed solely at the inner ear is elusive, it appears that autoimmune damage can also exist as an entity confined to the labyrinth. Antigenic targets of autoimmunity within the labyrinth seem to be diverse. Partly because of this, the condition is difficult to diagnose. However, autoimmune disorders of the inner ear are of special interest since they are among the few forms of hearing loss that are amenable to medical treatment. Recent progress in understanding the etiology, diagnosis and treatment of autoimmune damage to the inner ear is reviewed.

Autoimmune inner ear disease

The known etiologies of acquired sensorineural hearing loss include acoustic trauma, physical trauma, ototoxicity, genetic predisposition, infections, Meniere's disease, aging, and autoimmune disease. Treatments are directed at eliminating or managing the underlying disease process and aiding hearing with amplification. Rarely is it possible to improve unaided hearing after sensorineural loss except when the severe to profound level of loss is reached and cochlear implantation becomes an option. Autoimmune inner ear disease, however, is a treatable cause of sensorineural hearing loss and it is important for physicians and hearing health professionals to recognize that proper early diagnosis and management strategies may result in stabilization and possibly improvement in hearing.