Autoimmune vestibulo-cochlear disorders

The Role of Pericytes in Inner Ear Disorders: A Comprehensive Review

Inner ear disorders, including sensorineural hearing loss, Meniere's disease, and vestibular neuritis, are prevalent conditions that significantly impact the quality of life. Despite their high incidence, the underlying pathophysiology of these disorders remains elusive, and current treatment options are often inadequate. Emerging evidence suggests that pericytes, a type of vascular mural cell specialized to maintain the integrity and function of the microvasculature, may play a crucial role in the development and progression of inner ear disorders. The pericytes are present in the microvasculature of both the cochlea and the vestibular system, where they regulate blood flow, maintain the blood-labyrinth barrier, facilitate angiogenesis, and provide trophic support to neurons. Understanding their role in inner ear disorders may provide valuable insights into the pathophysiology of these conditions and lead to the development of novel diagnostic and therapeutic strategies, improving the standard of living. This comprehensive review aims to provide a detailed overview of the role of pericytes in inner ear disorders, highlighting the anatomy and physiology in the microvasculature, and analyzing the mechanisms that contribute to the development of the disorders. Furthermore, we explore the potential pericyte-targeted therapies, including antioxidant, anti-inflammatory, and angiogenic approaches, as well as gene therapy strategies.

Progress in protecting vestibular hair cells

Vestibular hair cells are mechanosensory receptors that are capable of detecting changes in head position and thereby allow animals to maintain their posture and coordinate their movement. Vestibular hair cells are susceptible to ototoxic drugs, aging, and genetic factors that can lead to permanent vestibular dysfunction. Vestibular dysfunction mainly results from the injury of hair cells, which are located in the vestibular sensory epithelium. This review summarizes the mechanisms of different factors causing vestibular hair cell damage and therapeutic strategies to protect vestibular hair cells.

Intratympanic infliximab is a safe and effective rescue therapy for refractory immune-mediated hearing loss

PURPOSE

To determine the efficacy and safety of the intratympanic infiltration of infliximab at the hearing threshold of patients in follow-up for refractory immune-mediated hearing loss.

METHODS

17 patients were collected with relapses, despite maintenance treatment with oral azathioprine associated or not with oral prednisone at low doses (between 5 and 7.5 ml/day) or refractory relapses to previous intratympanic corticoid treatment being 19 affected ears infiltrated. We measured the hearing threshold by Pure-Tone Average (PTA) 500-3000 Hz, 125-8000 Hz and 250-8000 Hz in pre-infiltration (baseline) and follow-up 3 weeks post-infiltration with auditory threshold at frequencies 125-8000 Hz.

RESULTS

The average age was 50.68 years (±15.23 years). After the administration of intratympanic infliximab, an improvement of the hearing threshold was showed in the Pure-Tone Average (PTA) calculated at 500-3000 Hz (p = 0.004), 125-8000 Hz (p = 0.001) and 250-8000 Hz (p = 0.006). An immediate improvement in low frequencies also was observed: 125, 250 and 500 Hz (p = 0.009, p = 0.002 and p < 0.001 respectively) also at 1000 Hz (p = 0.004) and a persistence of the effect at 3 months in the low frequencies: 125 Hz (p = 0.020), 250 Hz (p = 0.006) and 500 Hz (p = 0.002).

CONCLUSIONS

Infliximab intratympanic infiltration improves the hearing threshold in patients with immune-mediated hearing loss. The effect of improving the hearing threshold is higher in low frequencies and persists within 3 months of the infiltration. The administration of intratympanic infliximab is an effective and safe technique.

Blast-induced tinnitus: Animal models

Blast-induced tinnitus is a prevalent problem among military personnel and veterans, as blast-related trauma damages the vulnerable microstructures within the cochlea, impacts auditory and non-auditory brain structures, and causes tinnitus and other disorders. Thus far, there is no effective treatment of blast-induced tinnitus due to an incomplete understanding of its underlying mechanisms, necessitating development of reliable animal models. This article focuses on recent animal studies using behavioral, electrophysiological, imaging, and pharmacological tools. The mechanisms underlying blast-induced tinnitus are largely similar to those underlying noise-induced tinnitus: increased spontaneous firing rates, bursting, and neurosynchrony, Mn++ accumulation, and elevated excitatory synaptic transmission. The differences mainly lie in the data variability and time course. Noise trauma-induced tinnitus mainly originates from direct peripheral deafferentation at the cochlea, and its etiology subsequently develops along the ascending auditory pathways. Blast trauma-induced tinnitus, on the other hand, results from simultaneous impact on both the peripheral and central auditory systems, and the resultant maladaptive neuroplasticity may also be related to the additional traumatic brain injury. Consequently, the neural correlates of blast-induced tinnitus have different time courses and less uniform manifestations of its neural correlates.

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.

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.

Trichostatin A reduces cisplatin-induced ototoxicity through the STAT6 signaling pathway

Cisplatin-induced ototoxicity limits its wide application in the treatment of cancer. A number of pro-inflammatory factors have been shown to be involved in cisplatin-induced ototoxicity. Trichostatin A (TSA) is an anti-inflammatory agent that has been shown to exert protective effects against cisplatin-induced ototoxicity. In the present study, we hypothesized that TSA may protect cochlear hair cells from cisplatin-induced damage by regulating the interleukin (IL)-4/signal transducer and activator of transcription (STAT)6 signaling pathway. Wistar rat cochlear explants were cultured in DMEM. The differentially expressed genes of the basilar membrane were identified by microarray analysis of global expression profiles. Hair cells were stained with rhodamine phalloidin and observed under a scanning electron microscope to evaluate the protective effects of TSA against cisplatin-induced cochlear hair cell damage. The levels of cytokines in the supernatant of the cultured basilar membranes was measured using ELISA. STAT6 and phosphorylated (p-)STAT6 expression was measured by western blot analysis. Morphological observation revealed that cisplatin induced the disarrangement of the cochlear hair cells, as well as the fusion and detachment of the cilia, while these aberrant alterations were inhibited by TSA, suggesting that TSA exerts a protective effect against cisplatin-induced damage to hair cells. Furthermore, the increase in the expression of STAT6 and p-STAT6 induced by cisplatin was reversed by treatment with TSA, accompanied by the decreased expression of IL-1β, IL-4 and IL-6. Therefore, our data demonstrate that TSA reduces cisplatin-induced ototoxicity by inhibiting pro-inflammatory factor-mediated STAT6 signaling. Thus, TSA may be used to prevent the side-effects associated with the use of cisplatin in cancer treatment.

Protective effect of rosmarinic acid is through regulation of inflammatory cytokine in cadmium-induced ototoxicity

Cadmium ( Cd(2+) ) is an environmental contaminant that causes a variety of adverse effects. Auditory cells are sensitive to cadmium, and the cochlea is more vulnerable to cadmium toxicity than the other parts of the auditory system. Rosmarinic acid (RA) exhibits a wide spectrum of biological activities, mainly antioxidant and anti-inflammatory activities. However, the regulatory effects of RA in the auditory system have not been elucidated. In this study, we investigated the protective effects of RA on Cd(2+) -induced ototoxicity in vitro and ex vivo. The findings showed that RA inhibited Cd(2+) -mediated cell toxicity, reactive oxygen species generation, interleukin (IL)-6 and IL-1β production, the translocation of the apoptosis inducing factor into the nucleus and activation of caspases-3 in an auditory cell line, HEI-OC1. In addition, RA prevented the destruction of hair cell arrays in the rat organ of Cortiprimary explants in the presence of Cd(2+) . These results are expected to improve our understanding of the pharmacological mechanism of RA, and help develop potential therapeutic strategies against ototoxicity.

Cisplatin ototoxicity involves cytokines and STAT6 signaling network

We herein investigated the role of the STAT signaling cascade in the production of pro-inflammatory cytokines and cisplatin ototoxicity. A significant hearing impairment caused by cisplatin injection was observed in Balb/c (wild type, WT) and STAT4(-/-), but not in STAT6(-/-) mice. Moreover, the expression levels of the protein and mRNA of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, were markedly increased in the serum and cochlea of WT and STAT4(-/-), but not STAT6(-/-) mice. Organotypic culture revealed that the shape of stereocilia bundles and arrays of sensory hair cell layers in the organ of Corti from STAT6(-/-) mice were intact after treatment with cisplatin, whereas those from WT and STAT4(-/-) mice were highly distorted and disarrayed after the treatment. Cisplatin induced the phosphorylation of STAT6 in HEI-OC1 auditory cells, and the knockdown of STAT6 by STAT6-specific siRNA significantly protected HEI-OC1 auditory cells from cisplatin-induced cell death and inhibited pro-inflammatory cytokine production. We further demonstrated that IL-4 and IL-13 induced by cisplatin modulated the phosphorylation of STAT6 by binding with IL-4 receptor alpha and IL-13Rα1. These findings suggest that STAT6 signaling plays a pivotal role in cisplatin-mediated pro-inflammatory cytokine production and ototoxicity.

Immunosuppressive therapy for autoimmune inner ear disease

Autoimmune inner ear disease (AIED) is a rare disease that is diagnosed after clinical suspicion and response to corticosteroids. AIED manifests as progressive, bilateral, although often asynchronous, sensorineural hearing loss and can be associated with vestibular symptoms. Since its description as a defined disease entity in 1979, the initial mainstay of treatment remains high-dose corticosteroids. Several animal models have been developed to assist in determining efficacy of immunosuppression in AIED, and several clinical studies have also investigated the role of both steroid and steroid-sparing treatments. Here we discuss the basic science and clinical research surrounding the history of immunosuppressive therapy in AIED.

Blocking the glucocorticoid receptor with RU-486 does not prevent glucocorticoid control of autoimmune mouse hearing loss

BACKGROUND/AIMS

Glucocorticoids effectively manage autoimmune hearing loss, although the cochlear mechanisms involved are unknown. Previous studies of steroid-responsive hearing loss in autoimmune (lupus) mice showed glucocorticoids and mineralocorticoids were equally effective, suggesting the ion homeostasis functions of glucocorticoids may be as relevant as immunosuppression for control of autoimmune-induced inner ear disease. Therefore, to better characterize the role of the glucocorticoid receptor in autoimmune hearing loss therapy, its function was blocked with the antagonist RU-486 (mifepristone) during glucocorticoid (prednisolone) treatments.

METHODS

Following baseline auditory brainstem response (ABR) thresholds, MRL/MpJ-Fas(lpr) autoimmune mice were implanted with pellets providing combinations of 1.25 mg/kg of RU-486, 4 mg/kg of prednisolone, or their respective placebos. After 1 month, animals were retested with ABR and blood was collected for immune complex analyses.

RESULTS

Mice receiving no prednisolone (placebo + placebo and placebo + RU-486) showed continued declines in hearing. On the other hand, mice receiving prednisolone (prednisolone + placebo and prednisolone + RU-486) had significantly better hearing (p < 0.05) than the non-prednisolone groups. Immune complexes were significantly elevated in the placebo + RU-486 group, suggesting RU-486 effectively blocked glucocorticoid receptor-mediated immune suppression. These results showed that blockage of the glucocorticoid receptor with RU-486 did not prevent prednisolone's effects in the ear, suggesting its ion homeostasis actions via the mineralocorticoid receptor were more relevant in hearing control.

CONCLUSION

The mineralocorticoid receptor-mediated actions of glucocorticoids are potentially relevant in steroid-responsive hearing disorders, implying disrupted cochlear ion transport functions may underlie the vascular problems proposed in some forms of immune-mediated hearing loss.

Role of proinflammatory cytokines in cisplatin-induced vestibular hair cell damage

BACKGROUND

Cisplatin causes the impairment of inner ear functions, including hearing and balance, through the involvement of a number of mechanisms. However, no laboratory studies have been performed on involvement of inflammation-related events in cisplatin-mediated vestibular dysfunction.

METHODS

We evaluated the secretion of proinflammatory cytokines and nuclear factor-kappaB (NF-kappaB) activation in cisplatin-treated UB/UE-1 utricular epithelial cells. We also employed immunohistochemistry to detect proinflammatory cytokines and NF-kappaB expression in cisplatin-injected mice.

RESULTS

Productions of proinflammatory cytokines significantly caused the death of UB/UE1 cells by cisplatin. Pharmacologic inhibition of mitogen-activated protein (MAP) kinase/ERK kinase-1 (MEK1) or extracellular signal-regulated kinase (ERK) significantly attenuated the death of UB/UE1 cells caused by cisplatin and proinflammatory cytokines. Immunohistochemical studies revealed an increase in the expression of proinflammatory cytokines and NF-kappaB in both the cristae ampullae and utricle of cisplatin-injected mice.

CONCLUSIONS

These results suggest that proinflammatory cytokines may play an important role in the pathogenesis of cisplatin-mediated vestibulo-toxicity.

Evidence that cisplatin-induced auditory damage is attenuated by downregulation of pro-inflammatory cytokines via Nrf2/HO-1

Recently, we demonstrated that pro-inflammatory cytokines such as TNF-alpha, IL-1beta, and IL-6 played a critical role in cisplatin-induced cochlear injury and that flunarizine, known as a T-type Ca(2+) channel antagonist, induced a cytoprotective effect against cisplatin cytotoxicity in HEI-OC1 cells by the activation of NF-E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) cascade through PI3K-Akt signaling but calcium-independent pathway. We report here that flunarizine markedly attenuates cisplatin-induced pro-inflammatory cytokine secretion and their messenger RNA transcription as well as cisplatin cytotoxicity through the activation of Nrf2/HO-1 and downregulation of NF-kappaB. In HEI-OC1 cells, overexpression of Nrf2/HO-1 by gene transfer or pharmacological approaches attenuated cisplatin-induced cytotoxicity and pro-inflammatory cytokine production. On the contrary, inhibition of Nrf2/HO-1 signaling by pharmacological inhibitors or specific small interfering RNAs significantly abolished the beneficial effects of flunarizine. Flunarizine also attenuated cisplatin-mediated MAPK activation and pharmacological inhibition of MAPKs, especially MEK1/ERK, blocked cisplatin-induced NF-kappaB activation in HEI-OC1 cells. Furthermore, WT-Nrf2 overexpression effectively blocked MAPK activation after cisplatin exposure. Finally, orally administrated Sibelium, the trade name of flunarizine, suppressed the increase of pro-inflammatory cytokines by cisplatin in both serum and cochleas of mice, whereas it increased HO-1 expression in cochleas. These results indicate that flunarizine induces a protective effect against cisplatin ototoxicity through the downregulation of NF-kappaB by Nrf2/HO-1 activation and the resulting inhibition of pro-inflammatory cytokine production in vitro and in vivo.

The pharmacokinetic profiles of dexamethasone and methylprednisolone concentration in perilymph and plasma following systemic and local administration

CONCLUSION

Both methylprednisolone (MTH) and dexamethasone (DEX) could successfully and effectively penetrate the round window membrane (RWM) into perilymph. RWM topical application and otocyst infusion with MTH and DEX result in high perilymph drug concentrations and low plasma levels. An intratympanic administration schedule for DEX or MTH could be carried out twice daily.

OBJECTIVE

To explore the pharmacokinetics of DEX and MTH in the inner ear fluids and plasma following systemic and local administration.

MATERIALS AND METHODS

Three routes of administration of steroids were used in guinea pigs: intracardial injection, otocyst infusion and RWM topical application by granule gelfoam soaked with steroids. Samples of blood or perilymph of the scala tympani were collected at 1-6 h after administration. High-performance liquid chromatography was used to assay concentrations of steroids.

RESULTS

Both the topical application and infusion administration resulted in a significantly higher concentration of steroids in perilymph than intracardial injection. The level of steroids in the perilymph reached a peak at 1-2 h after dosing, and this was maintained at a relatively high level for several hours. The intracardial injection with steroids yielded very low perilymph levels at all sampling times after administration.

Sensorineural dysacusis in patients with systemic lupus erythematosus

The objective of this study was to establish the frequency of involvement of the auditory apparatus in 45 female patients with systemic lupus erythematosus (SLE) submitted to general clinical and laboratory assessments, and tone and vocal audiometry accompanied by a questionnaire evaluating auditory symptoms. The control group consisted of 45 healthy women, matched by age. Auditory symptoms were present in 25 (55.5%) patients, with a diagnosis of sensorineural hearing loss in seven (15.6%) patients. A significant correlation with hypoacusis (P < 0.001), ear fullness (P = 0.012) and tinnitus (P = 0.017) was observed in patients with hearing loss. None of the clinical or laboratory parameters showed an association with sensorineural hearing loss. In the control group, three women (6.7%) presented audiometric alterations, including two with altered tympanometry results and one with mild sensorineural hearing loss. In conclusion, an adequate investigation of auditory symptoms is important during the follow-up of patients with SLE, since manifestations of the auditory apparatus and sensorineural hearing loss can affect a significant proportion of patients.

Cisplatin cytotoxicity of auditory cells requires secretions of proinflammatory cytokines via activation of ERK and NF-kappaB

The ototoxicity of cisplatin, a widely used chemotherapeutic agent, involves a number of mechanisms, including perturbation of redox status, increase in lipid peroxidation, and formation of DNA adducts. In this study, we demonstrate that cisplatin increased the early immediate release and de novo synthesis of proinflammatory cytokines, including TNF-alpha, IL-1beta, and IL-6, through the activation of ERK and NF-kappaB in HEI-OC1 cells, which are conditionally immortalized cochlear cells that express hair cell markers. Both neutralization of proinflammatory cytokines and pharmacologic inhibition of ERK significantly attenuated the death of HEI-OC1 auditory cells caused by cisplatin and proinflammatory cytokines. We also observed a significant increase in the protein and mRNA levels of proinflammatory cytokines in both serum and cochleae of cisplatin-injected rats, which was suppressed by intraperitoneal injection of etanercept, an inhibitor of TNF-alpha. Immunohistochemical studies revealed that TNF-alpha expression was mainly located in the spiral ligament, spiral limbus, and the organ of Corti in the cochleae of cisplatin-injected rats. NF-kappaB protein expression, which overlapped with terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling-positive signal, was very strong in specific regions of the cochleae, including the organ of Corti, spiral ligament, and stria vascularis. These results indicate that proinflammatory cytokines, especially TNF-alpha, play a central role in the pathophysiology of sensory hair cell damage caused by cisplatin.

Vestibular symptoms in children with enlarged vestibular aqueduct anomaly

OBJECTIVE

The objective of this study is to describe the vestibular symptoms in pediatric patients with enlarged vestibular aqueduct (EVA) anomaly.

METHODS

Retrospective chart review of pediatric and adult patients with EVA anomaly who were treated at the University of Utah Hospital or Primary Children's Medical Center, between 1995 and 2005. Radiographs were reviewed to confirm the diagnosis. Comparisons were made between adult and pediatric patients.

RESULTS

Thirty-two patients were included in the study, 17 females and 15 males. Twenty-one patients were under the age of 18 and 11 patients were age 18 or older. On initial audiometric evaluation at a tertiary hospital, the pure tone average in the right ear was 75.0 dB and the pure tone average in the left ear was 80.4 dB. The incidence of vestibular symptoms in adult patients was 45.5% and in pediatric patients was 48.0%. Fourteen patients underwent cochlear implantation. Four patients (28.6%) who previously denied vestibular symptoms experienced post-operative vertigo after cochlear implantation.

CONCLUSIONS

About half of the patients with EVA in our series experienced vestibular symptoms. Pediatric patients in our series experienced vertigo and vestibular symptoms with equal frequency when compared to adult patients. Some patients with EVA undergoing cochlear implantation experienced vestibular symptoms in the post-operative period.

TNFα blockers do not improve the hearing recovery obtained with glucocorticoid therapy in an autoimmune experimental labyrinthitis

The effectiveness of etanercept [tumour necrosis factor-alpha (TNFalpha) blocker] and corticoids in treating immuno-mediated inner ear disease (IMIED) was compared in an animal model of autoimmune labyrinthitis. IMIED is one of the few forms of sensorineural hearing loss that is reversible with proper medical treatment. While the effectiveness and usefulness of immunomodulating agents (corticosteroids) in treating IMIED have been demonstrated, TNFalpha antagonists, which inhibit granuloma formation in rheumatoid arthritis and other autoimmune diseases, have been considered as an alternative therapy. The efficacy of etanercept (anti-TNFalpha) was evaluated in a guinea pig model of experimental autoimmune labyrinthitis in which 25 guinea pigs were divided in a control group, which was used to document the rise in hearing thresholds following immunisation, and two experimental groups, which were treated with steroids (6-methylprednisolone) and anti-TNFalpha (etanercept), respectively, after the immunisation. Comparison of the auditory thresholds obtained by means of auditory brainstem response (ABR) revealed that the auditory thresholds of the two experimental groups were not statistically different (6-methylprednisolone: 41.5 dB, SD: 8.51; etanercept: 37.5 dB, SD: 7.91) and that both compared favourably with that of the control group (60 dB, SD: 7.91) at p=0.001. We therefore conclude that etanercept is as effective as glucocorticoids in an animal model of autoimmune labyrinthitis; however, the potential adverse effects and high price of the former advise against its use as an initial therapy for IMIED.

The remediation of hearing deterioration in children with large vestibular aqueduct syndrome

Based on imaging findings, large vestibular aqueduct syndrome (LVAS) in early childhood is the most common cause of sensorineural hearing loss. Children with LVAS are at a high risk of suffering sudden deteriorations in hearing. This study was to review treatment of sudden hearing deterioration in children with LVAS who underwent corticosteroid therapy. We conducted a retrospective study of patients presenting to an academic tertiary medical center. Sixteen children of LVAS were evaluated. Corticosteroid therapy (prednisolone 1-2 mg/(kg day) or equal titer's dexamethasone) was administered as soon as sudden hearing loss developed. The pure tone audiometric result improved more than 10dB at two or more consecutive frequencies and was regarded as a significant response to corticosteroid therapy. Sixteen cases comprising 12 boys and 4 girls were retrospectively analyzed in this study. The mean age at which LVAS was diagnosed was 2.3 years. Mean follow-up for the 16 cases from the first clinic visit to November 2003 was 4.2 years. The initial audiograms varied from down-sloping, valve or rising patterns. In addition, bilateral enlargement of the vestibular aqueduct was found to all children and the mean diameter of right and left ears were 7.23 and 6.83 mm, respectively. Seven children had totally experienced 13 episodes of sudden hearing deterioration. After receiving corticosteroid therapy in time, 11 of 13 episodes had indicated significant responses to treatment, a response rate of 85%. Early detection of LVAS and the timing of treatment are crucial for preventing the residual hearing from deteriorating. As soon as the hearing deterioration of a child with LVAS is recognized, aggressive intervention such as corticosteroid therapy should be performed in no time.

Etanercept therapy for immune-mediated cochleovestibular disorders: A multi-center, open-label, pilot study

OBJECTIVE

Immune-mediated cochleovestibular disorders (IMCVDs) continue to present a diagnostic and therapeutic challenge. Antirheumatic agents, commonly employed for IMCVDs, are associated with variable efficacy and sometimes with serious side effects. The objective of the current study was to preliminarily evaluate the efficacy of etanercept therapy for IMCVD.

METHODS

In this open-label prospective pilot study, 23 patients with bilateral IMCVDs or symptoms of bilateral Meniere's disease were treated with etanercept (25 mg twice weekly, by subcutaneous injection) for 24 weeks. All participants showed progressive hearing loss within 3 months prior to the study and responded to prednisone therapy. Hearing improvement was defined as an improvement of sensorineural hearing from baseline, in at least one ear, of 15 dB or more in the pure-tone air conduction thresholds, or an increase of more than 12% in word identification score. When present, vertigo and tinnitus were assessed by frequency and severity of attack and a functional level scale. Limited serial positron emission tomography (PET) of the inner ear region was performed in 5 patients to assess disease activity.

RESULTS

There were 12 female (52%) and 11 male patients with a mean age of 48 years. Hearing improved in 7 (30%) patients, was unchanged in 13 (57%), and worsened in 3 (13%). Of 21 patients with tinnitus, this symptom improved in 7 (33%), was unchanged in 10 (48%), and worsened in 3 (13%). Of 16 patients with vertigo, 8 (50%) were improved, 7 (47%) unchanged, and 1 (3%) worse at the end of the study. Etanercept was generally well tolerated. PET was positive on one ear of 2 of 5 patients, remained positive with treatment on 1 of these, and was initially positive in 1 deaf ear, becoming negative at followup.

CONCLUSION

These prospective pilot data suggest that etanercept therapy is safe among patients with IMCVDs. However, these data do not suggest substantial efficacy of etanercept among patients with IMCVDs in improving hearing loss. There appeared to be stabilization or improvement of hearing in 87% in this group of patients with pretreatment intractable progressive hearing loss. However, the study endpoint of improvement in 70% of patients was not attained. This short-term effect of possible stabilization requires further study. PET scanning was not useful as a tool to evaluate hearing loss in a limited subset of patients.

Intratympanic corticosteroids for Meniere's disease and vertigo

Hearing loss can be caused by acoustic trauma, aging, ototoxic medications, and various other causes. At the cellular level hearing loss seems to be mediated by reactive oxygen species and ultimately through the activation of apoptotic mechanisms. This article explains the cellular and molecular mechanisms of hearing loss and presents medications that could be used in the intratympanic treatment of hearing loss.

A novel class II-binding motif selects peptides that mediate organ-specific autoimmune disease in SWXJ, SJL/J, and SWR/J mice

Idiopathic dilated cardiomyopathy (DCM) is responsible for approximately 25% of all cases of congestive heart failure. We have recently shown that immunization of autoimmune-susceptible SWXJ mice with whole cardiac myosin leads to T cell-mediated experimental autoimmune myocarditis (EAMC) and DCM. We have now identified two disease-inducing peptides from cardiac alpha-myosin heavy chain (CAMHC). Our approach involved the use of a novel MHC class II-binding motif contained in several peptides known to be immunogenic in SWXJ (H-2(q,s)) mice or in the parental SJL/J (H-2(s)) or SWR/J (H-2(q)) mouse strains. Two of four CAMHC peptides containing the -KXXS- peptide motif were found to be immunogenic. Immunization of SWXJ or parental SJL/J and SWR/J mice with CAMHC peptides palpha406-425 or palpha1631-1650 resulted in EAMC and DCM, characterized by inflammation, fibrosis, and decompensated right-sided ventricular dilatation. Despite mediating high incidences of severe disease, both peptides were found to be cryptic determinants, thereby providing further evidence for the importance and perhaps predominance of self crypticity in autoimmunity. Both peptides showed dual parental I-A(q) and I-A(s) restriction and mediated passive transfer of disease with activated CD4(+) T cells. An intact motif was necessary for antigenicity because loss of activity occurred in peptides containing nonconservative substitutions at the motif's terminal lysine and serine residues. Our studies provide a new model for EAMC and DCM in strains of mice widely used in autoimmune studies. Moreover, the -KXXS- motif may be particularly useful in implicating previously overlooked proteins as autoimmune targets and in facilitating the development of new organ-specific autoimmune mouse models for human diseases.

Inflammatory signals increase Fas ligand expression by inner ear cells

There is considerable evidence that hearing and vestibular function can be influenced by immune processes. The inner ear has evolved mechanisms, such as the blood-labyrinthine barrier that limit immune responses and autoimmune processes to reduce the potential for damage to cochlear cells. Recently, expression of Fas ligand (FasL) in some non-lymphoid tissue, as in the anterior chamber of the eye, has been hypothesized to play a role in protection of sensitive organs from activated T-cells. We show that under resting conditions, cochlear cells express little or no FasL. However, after exposure to interferon-gamma in vitro, FasL is induced in many neonatal cochlear cells. In addition, we show that FasL is upregulated in adult cochlear cells after induction of a sterile labyrinthitis in vivo. The induction of FasL by inflammation may serve to limit cochlear immune responses, and to protect sensorineural tissue from immune and autoimmune damage.