Anti-heat shock protein 70 antibodies in Meniere's disease

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

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

Western Blot Immunoassay for HSP-70 Antibodies in Idiopathic Tinnitus: A Preliminary Report

Objectives:

Our preliminary study investigated the role of nonspecific immunologic tests and immunoassay for heat shock protein 70 (HSP-70) in supporting the possibility of an autoimmune inner ear process determining idiopathic tinnitus.

Methods:

Thirty-six consecutive patients with idiopathic tinnitus without other otologic or autoimmune diseases and 20 healthy blood donor subjects underwent determinations of circulating immune complexes (CICs) and other nonspecific immunologic factors and immunoassay for HSP-70.

Results:

The mean CIC values were 4.2 μg/mL in the tinnitus patients and 0.9 μg/mL in the control group (p = .012). Thirteen of the 36 tinnitus patients and none of the control group were HSP-70-positive. Ten of the 13 HSP-70-positive patients had CIC values higher than normal. In the tinnitus group, the mean CIC values were 6.9 μg/mL and 2.6 μg/mL in the HSP-70-positive and –negative subgroups, respectively (p = .024).

Conclusions:

It may be hypothesized that in a significant number of cases, idiopathic tinnitus could be induced by immune response to inner ear–specific HSP-70.

HSP70 antibodies in 80 patients with "clinically certain" Meniere's disease

OBJECTIVES

We tested the claim that a significant proportion of patients with Meniere's disease have antibodies to heat shock protein 70 (HSP70) antigen, which may lead to defective endolymphatic sac function and vertigo attacks.

METHODS

Serum samples were taken from 80 subjects with a "certain" diagnosis of Meniere's disease (American Academy criteria plus electrocochleographic confirmation of endolymphatic hydrops with tone burst stimuli) and were tested for HSP70 antibodies with the OTOblot (hsp70) Western blot assay. The response was recorded as negative, positive, or equivocal. Samples from 80 sex- and age-matched blood donors were used as controls.

RESULTS

Of 80 patients with "clinically certain" Meniere's disease, 14 were positive for HSP70 antibodies or equivocal; of 80 controls, 10 were positive or equivocal. There was no significant difference (p=0.239). There was no correlation with bilateral disease, "activity" of Meniere's disease, or stage of Meniere's disease.

CONCLUSIONS

Patients with an unequivocal diagnosis of Meniere's disease do not have a significantly raised incidence of HSP70 antibodies.

Genetic investigations of Meniere's disease

Meniere's disease remains a disorder of unknown origin despite the collective efforts to determine the pathogenesis, although experts have long recognized that disease development likely has some heritable component. Although genetic studies of Meniere's disease have been inconclusive, increasing knowledge of human genetic structure and mutation and investigative techniques have potential to further understanding of this disorder.

HLA-B27-Associated Bilateral Ménière Disease

We describe 2 cases of bilateral Ménière disease with features resembling autoimmune inner ear disease in patients who were found to be carriers of human leukocyte antigen (HLA) B27. For immunohistochemical analysis, mouse inner ear sections were used as the tissue substrate for reaction with serum. Both patients demonstrated an increased immunofluorescence reaction compared with a normal control. We suggest that an antibody-mediated mechanism may be responsible for HLA-B27–associated Ménière disease.

Multidimensional degradomics identifies systemic autoantigens and intracellular matrix proteins as novel gelatinase B/MMP-9 substrates

The action radius of matrix metalloproteinases or MMPs is not restricted to massive extracellular matrix (ECM) degradation, it extends to the proteolysis of numerous secreted and membrane-bound proteins. Although many instances exist in which cells disintegrate, often in conjunction with induction of MMPs, the intracellular MMP substrate repertoire or degradome remains relatively unexplored. We started an unbiased exploration of the proteolytic modification of intracellular proteins by MMPs, using gelatinase B/MMP-9 as a model enzyme. To this end, multidimensional degradomics technology was developed by the integration of broadly available biotechniques. In this way, 100-200 MMP-9 candidate substrates were isolated, of which 69 were identified. Integration of these results with the known biological functions of the substrates revealed many novel MMP-9 substrates from the intracellular matrix (ICM), such as actin, tubulin, gelsolin, moesin, ezrin, Arp2/3 complex subunits, filamin B and stathmin. About 2/3 of the identified candidates were autoantigens described in multiple autoimmune conditions and in cancer (e.g. annexin I, nucleolin, citrate synthase, HMGB1, alpha-enolase, histidyl-tRNA synthetase, HSP27, HSC70, HSP90, snRNP D3). These findings led to the insight that MMPs and other proteases may have novel (immuno)regulatory properties by the clearance of toxic and immunogenic burdens of abundant ICM proteins released after extensive necrosis. In line with the extracellular processing of organ-specific autoantigens, proteolysis might also assist in the generation of immunodominant 'neo-epitopes' from systemic autoantigens. The study of proteolysis of ICM molecules, autoantigens, alarmins and other crucial intracellular molecules may result in the discovery of novel roles for proteolytic modification.

Anti-68 kDa antibodies in autoimmune sensorineural hearing loss: are these autoantibodies really a diagnostic tool?

OBJECTIVES

Autoimmune sensorineural hearing loss (ASNHL) is a relatively rare disorder which can lead to total deafness. At present, no specific laboratory test with adequate sensitivity and specificity is available to confirm the clinical suspicion of ASNHL. The aim of this study was to identify if evaluation of anti-hsp70 antibodies is an accurate diagnostic tool in patients affected by ASNHL.

STUDY DESIGN

Prospective study.

METHODS

During 4-year (2001-2005), all patients with SNHL who were referred to the Eye, Ear, Nose and Throat Department of Parma University, Italy, underwent specific tests to determine the autoimmune origin of the disease. Patients with a consistent suspicion of ASNHL underwent the routine serologic tests and a test for determination of anti-hsp70 antibodies. The same patients were divided into three groups: (1) idiopathic ASNHL; (2) ASNHL associated with ocular inflammation, i.e. Cogan's Syndrome; (3) ASNHL associated with a systemic autoimmune disease (SAD). The control group included: (1) healthy subjects; and (2) patients affected by SAD, without any ocular or audiovestibular disease.

RESULTS

88 subjects (67 patients, defined as "study group", and 21 controls) were evaluated. Anti-hsp70 antibodies were isolated in 52% of the study group patients, and in 4% of the control group (chi2 = 13.009, p < 0.01). In the idiopathic ASNHL patients, 59.5% were found positive for anti-hsp70 antibodies. About 50% of patients affected by CS and 37.5% of patients affected by SAD with SNHL were found positive. In the control group, anti-hsp70 antibodies were found in 8.3% of healthy subjects and in none of the patients with SAD and no hearing loss.

CONCLUSIONS

The present study confirms the value of the anti-hsp70 test in the serological diagnosis of autoimmune hearing loss. It is still the only available diagnostic marker that identifies an autoimmune origin of hearing loss.

Antibodies against heat shock proteins in environmental stresses and diseases: friend or foe?

Heat shock proteins (Hsps) can be found in two forms, intracellular and extracellular. The intracellular Hsps are induced as a result of stress and have been found to be cytoprotective in many instances due to their chaperone functions in protein folding and in protein degradation. The origin and role of extracellular Hsps is less clear. Although they were suspected originally to be released from damaged cells (necrosis), their presence in most normal individuals rather suggests that they have regulatory functions in circulation. As immunodominant molecules, Hsps can stimulate the immune system, leading to the production of autoantibodies recognizing epitopes shared by microbial and human Hsps. Thus, extracellular Hsps can influence the inflammatory response as evidenced by the production of inflammatory cytokines. Antibodies to Hsps have been found under normal conditions but seem to be increased in certain stresses and diseases. Such antibodies could regulate the inflammatory response positively or negatively. Here, we review the literature on the findings of antibodies to Hsps in situations of environmental or occupational stress and in a number of diseases and discuss their possible significance for the diagnosis, prognosis, or pathogenesis of these diseases.

Autoimmune inner ear disease

PURPOSE OF REVIEW

The role of the immune system in mediating inner ear pathology has received considerable attention over the past two decades. The purpose of this paper is to summarize recent basic science research into the pathogenesis of autoimmune inner ear disease (AIED), review the current diagnostic work-up for patients with suspected AIED, and delineate treatment strategies.

RECENT FINDINGS

Basic science and clinical studies have been performed to delineate the mechanisms by which autoimmune processes may affect the ear and to develop treatment strategies to reverse this pathology. AIED refers to a rapidly progressive (over a course of weeks to months) sensorineural hearing loss that responds to the administration of corticosteroids. In addition, systemic autoimmune diseases (eg, vasculitides, lupus, Wegener granulomatosis) can secondarily affect the inner ear. Although a number of diagnostic tests for AIED have been advocated, the diagnosis of this entity is still predicated on a positive therapeutic response to corticosteroid administration. Alternate immunosuppressive regimens, designed to be used in patients who cannot be weaned off corticosteroids or whose disease becomes refractory to treatment, have proven to be difficult to develop. Methotrexate, which initially showed promise, has recently been shown to be ineffective in preventing progression of hearing loss. Further research is required to better delineate the pathophysiologic mechanisms involved in AIED and to establish more effective and better tolerated treatment regimens.

SUMMARY

The original enthusiasm that was generated by the concept that immune-mediated mechanisms may mediate reversible forms of inner ear pathology has been tempered by the realities conveyed by scientific research. The pathophysiology of AIED is still not well understood. Multiple potential mechanisms have been identified that can result in immune-mediated inner ear pathology. The diagnosis of AIED is based on clinical presentation and response to the administration of corticosteroids. Diagnostic testing may support the diagnosis, and the results of a recent multicenter study should clarify the role of immunologic testing in the diagnosis of this entity. Treatment options are limited, with corticosteroids being the only validated treatment option, and methotrexate offering no significant benefit to patients. The role of cyclophosphamide is restricted to patients willing to endure the attendant risks. With the advent of cochlear implants, the administration of toxic medications to preserve hearing at all costs is a less desirable option.

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.

Antibodies to HSP70 and HSP90 in serum in non-small cell lung cancer patients

Heat shock proteins (HSPs) are components of a physiologic stress response that are also over-expressed in various cancers including non-small cell lung cancer (NSCLC). During NSCLC serum-antibody screening of a NSCLC cDNA T7 phage library for immunogenic proteins we isolated HSP70 and HSP90 proteins. Isolation of these proteins suggested that corresponding antibodies could be elevated in NSCLC patient sera, a novel finding that could pilot their use as markers of NSCLC. We showed histochemically that patient sera were more reactive with each phage-expressed protein than normal sera. Antibody affinity for each phage-expressed protein was confirmed by limiting the dilution of individual sera assayed by Ab enzyme-linked immunosorbent assay (ELISA). Sera from 49 NSCLC patients assayed by Ab ELISA and normalized to 40 controls showed that HSP70 antibodies were significantly greater in patient sera than in normals (P=0.0002), while HSP90 antibodies were not significantly different (P=0.11). Analysis of the results with logistic regression and receiver operating characteristics (ROC) curves showed that HSP70 antibodies were modest markers of NSCLC (sensitivity 0.74 and specificity 0.73; area under the curve or AUC=0.731), while HSP90 antibodies appeared to be poor in both criteria with an AUC of 0.602. Further evaluation of HSP70 antibodies as potential markers of disease may be rational.

Do middle ear muscles trigger attacks of Menière's disease?

OBJECTIVE

Current surgical methods for treating Ménière's disease (MD), e.g. endolymphatic sac surgery, mastoidectomy or insertion of middle ear ventilation tubes, only improve vertigo and fail to influence the hearing threshold. In this retrospective study we examined the long-term effects of tenotomy on the symptoms of MD.

MATERIAL AND METHODS

A total of 45 patients suffering from definite MD underwent middle ear muscle tenotomy, a treatment that is very rarely considered nowadays. Of these 45 patients, 20 were observed postoperatively for a period of > 2 years. The disease was scored pre- and postoperatively and the results were evaluated according to the American Academy of Otolaryngology-Head and Neck Surgery Committee on Hearing and Equilibrium guidelines for the diagnosis and evaluation of therapy for MD.

RESULTS

Sectioning of the tensor tympani and stapedius muscle tendons significantly reduced the frequency and intensity of vertigo and improved both the functional profile and tinnitus. Pure-tone audiometry at frequencies between 500 and 3000 Hz substantiated the improvement in hearing threshold, as did the pure-tone average. The therapeutical outcome was stable in cases where both tendons remained persistently disconnected. Intratympanal inflammatory reactions were observed in most patients during surgery.

CONCLUSION

Our results prove that tenotomy is a successful and enduring therapeutic approach for treating the auditory and vestibular symptoms of MD and strongly suggest that it should be reconsidered as a promising surgical treatment for the symptoms of MD.

Antibodies against the human heat shock protein hsp70 in patients with severe coronary artery disease

Heat shock proteins (hsps) play complex role in the function of the immune system, they can activate both humoral and cellular immune response, as well the complement system. Although autoimmunity to hsp70 was implicated in certain autoimmune diseases and other conditions, the exact role of anti-hsp70 antibodies is not known. It was demonstrated by our previous work and other's findings that antibodies against the 60 kDa hsps are strongly associated with coronary atherosclerosis and carotis disease. It is also known that there is increased hsp70 expression at different sites of atherosclerosis. Therefore our aim was to study whether level of anti-hsp70 antibodies correlate with the presence of severe coronary artery disease (CAD). We measured and compared anti-hsp70 IgG antibody levels in CAD patients (n = 99) and healthy subjects (n = 99) with ELISA. The frequency of these antibodies was high in both groups and there was no significant difference in the median level of anti-hsp70 antibodies between patients with severe CAD and controls (653 (400-1141) vs. 630 (326-1152) AU/mL, P = 0.337). Adjustment for age, sex, BMI and lipid parameters did not change this result. Furthermore we did not find a correlation between anti-hsp70 antibody levels and certain risk factors of CAD (age, lipid parameters, body mass index, C-reactive protein, gender, smoking, diabetes and anti-hsp60 antibodies). By contrast, in accordance with our previous findings, anti-hsp60 and anti-hsp65 antibody levels were significantly higher in CAD patients, compared to this control group (p < 0.0001 for both variables). We did not find any correlation between the levels of anti-hsp70 and anti-hsp60 or anti-hsp65 antibodies either in the patients or the controls. The exact role of hsp70 in atherosclerosis is controversial, but we suggest that humoral immunity against human hsp70 does not contribute to coronary atherosclerosis in contrast to antibodies against 60kDa hsps.

Immunologic and serologic testing in patients with Ménière's disease

OBJECTIVE

To establish the value of immunologic and serologic testing in patients with Ménière's disease.

STUDY DESIGN

Prospective cohort.

SETTING

University-based, tertiary care balance center.

INTERVENTION

Patients with active unilateral or bilateral Ménière's disease underwent testing, including antinuclear antibodies, anti-DNA antibodies, rheumatoid factor, complement levels, anti-Sjögren syndrome A and B antibodies, sedimentation rate, antiphospholipid antibodies, Western blot for anticochlear antibodies (anti-heat shock protein 70), microhemagglutination test for Treponema pallidum, and Lyme titers.

OUTCOME MEASURES

Results of laboratory tests.

RESULTS

In patients with unilateral Ménière's disease (n = 40), 27% demonstrated elevated antiphospholipid antibody titers (population norm, 6-9%). The majority of these patients manifested negative assays on the other tests listed above. In patients with bilateral Ménière's disease (n = 18), elevations in antinuclear antibody titers (38%) were the most notable finding. As part of a broader study of patients with progressive hearing loss, four patients with positive syphilis titers were identified; however, none of these patients complained of vertigo.

CONCLUSION

In general, the results of this study do not support the hypothesis that immune or infectious pathologies are involved in the pathogenesis of unilateral Ménière's disease. In particular, Lyme disease does not seem to cause labyrinthine disease. However, the potential role of the thrombogenic antiphospholipid antibodies must be further investigated. Patients with bilateral Ménière's disease may be more likely to have a systemic autoimmune process.

Prevalence of heat shock protein in patients with Meniere's disease and allergy

OBJECTIVE

The study purpose was to investigate the prevalence of elevated heat shock protein 70 (HSP-70) in patients with Meniere's disease who have milk allergy compared with those who are not allergic to milk.

METHODS

Fifty-five patients with Meniere's disease and allergy in whom milk allergy had been confirmed by intradermal progressive dilutional food testing or skin testing to milk antigen were included. Blood serum was tested for HSP-70 elevation with a Western blot assay using bovine renal extract. The 29 women and 26 men ranged in age from 29 to 76 years (mean age 52.8 years). Forty percent of the patients had bilateral Meniere's disease.

RESULTS

Overall prevalence of HSP-70 elevation was 29.1%. This was higher in bilateral patients (50%) than unilateral patients (15%) (P <or= 0.007). The effect was based primarily on elevated HSP-70 in bilateral (62.5%) and unilateral (7.7%) patients in those with no milk allergy (P <or= 0.006). The prevalence of HSP-70 elevation was actually lower in those with milk allergy (19.2%) than in those with no milk allergy (37.9%). This difference was statistically significant only in the subset of patients who were <50 years old (0% vs 33.3%, respectively; P <or= 0.04).

CONCLUSIONS

We found no relationship between the presence of antibodies to HSP-70 and allergy to milk. The significance of elevated HSP-70 in patients with Meniere's disease has yet to be defined.

Does the serological testing really play a role in the diagnosis immune-mediated inner ear disease?

In order to analyse the clinical presentation and laboratory tests used for the diagnosis of immune-mediated sensorineural hearing loss (IMSNHL) a prospective study was conducted involving 125 patients affected by diverse clinical forms of the disease. The following methods were used: analysis of clinical evolution, pure-tone audiometry, determination of the immunophenotype of peripheral blood lymphocytes, immunoglobulins, complement factors C3 and C4, erythrocyte sedimentation rate, antinuclear autoantibodies (ANA) and heat shock protein 70 and the response to therapy. Levels CD4 (p = 0.03) and CD4CD45RA (p = 0.002) T cells were significantly reduced in patients with sudden sensorineural hearing loss. ANA were found in 34.4% of patients and the incidence of antibodies to HSP-70 was similar in both patients and control subjects. Diagnosis of IMSNHL is still based on clinical impressions as laboratory testing is not sufficiently diagnostic. However, the long-term evolution of IMSNHL presented by the patients included in this study may explain the negative results obtained in the tests. The existence of a typical profile patient, including the clinical course, immunological changes (presence of ANA and detection of abnormalities in T-cell subpopulations) and the response to steroid therapy can facilitate diagnosis. Further investigation to help identify a specific marker characteristic of IMSNHL is required.

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.