Monocytes, Macrophages, and Microglia and the Role of IL-1 in Autoimmune Inner Ear Disease (AIED)

A novel cell-free therapy using exosomes in the inner ear regeneration

Cellular and molecular alterations associated with hearing loss are now better understood with advances in molecular biology. These changes indicate the participation of distinct damage and stress pathways that are unlikely to be fully addressed by conventional pharmaceutical treatment. Sensorineural hearing loss is a common and debilitating condition for which comprehensive pharmacologic intervention is not available. The complex and diverse molecular pathology that underlies hearing loss currently limits our ability to intervene with small molecules. The present review focuses on the potential for the use of extracellular vesicles in otology. It examines a variety of inner ear diseases and hearing loss that may be treatable using exosomes (EXOs). The role of EXOs as carriers for the treatment of diseases related to the inner ear as well as EXOs as biomarkers for the recognition of diseases related to the ear is discussed.

Role of Inner Ear Macrophages and Autoimmune/Autoinflammatory Mechanisms in the Pathophysiology of Inner Ear Disease

Macrophages play important roles in tissue homeostasis and inflammation. Recent studies have revealed that macrophages are dispersed in the inner ear and may play essential roles in eliciting an immune response. Autoinflammatory diseases comprise a family of immune-mediated diseases, some of which involve sensorineural hearing loss, indicating that similar mechanisms may underlie the pathogenesis of immune-mediated hearing loss. Autoimmune inner ear disease (AIED) is an idiopathic disorder characterized by unexpected hearing loss. Tissue macrophages in the inner ear represent a potential target for modulation of the local immune response in patients with AIED/autoinflammatory diseases. In this review, we describe the relationship between cochlear macrophages and the pathophysiology of AIED/autoinflammatory disease.

NaCl exposure results in increased expression and processing of IL-1β in Meniere's disease patients

Meniere's disease (MD) is a chronic disease that causes episodic vertigo, fluctuating hearing loss, and aural fullness, initially managed by dietary salt reduction, and use of diuretics. Our prior research in autoimmune inner ear disease (AIED) demonstrated that in peripheral blood mononuclear cell (PBMC) from corticosteroid-resistant AIED patients, increased production, processing and release of interleukin-1β (IL-1β) is observed and hearing could be improved with use of anakinra, an interleukin-1 receptor antagonist. We have further identified that in these AIED patients, IL-1β is uniquely processed to a 28 kDa pro-inflammatory product by caspase-7. In the present study, we characterize the production, processing and release of the pro-inflammatory cytokines IL-1β and IL-6 from PBMC of MD (n = 14) patients in response to sodium chloride (NaCl), and determined the effect of the diuretic triamterene-hydrocholothiazide (T-HCTZ), or anakinra in these patients. We observed that PBMC cultured with NaCl from MD patients show processing of IL-1β to the 28 kDa product, and that this product is abrogated with T-HCTZ. Our observations are consistent with other autoimmune diseases where high concentrations of NaCl caused release of pro-inflammatory cytokines and may provide further insight as to the mechanism of disease progression in MD patients.

Autoimmune inner ear disease: A systematic review of management

OBJECTIVES

The study systematically reviewed the existing literature on the management of autoimmune inner ear disease (AIED).

STUDY DESIGN

Systematic review.

METHODS

We performed a literature search of Embase, NCBI, Cochrane, and Web of Science databases from April 1990 to April 2020. Inclusion criteria included studies that were retrospective or prospective in nature evaluating the treatment of AIED with audiometric data measuring hearing outcomes during treatment. Hearing improvement was the primary study outcome and improvement in vestibular symptoms was the secondary study outcome.

RESULTS

Sixteen of 412 candidate articles were included in our study. Systemic steroid treatment is most commonly described. Alternative treatment modalities included intratympanic steroid treatment, methotrexate, cyclophosphamide, azathioprine, infliximab, etanercept, adalimumab, golimumab, methylprednisolone, rituximab, and anakinra.

CONCLUSION

Systemic corticosteroids are the first line treatment of AIED. Intratympanic steroids are a potential adjuvant or alternative treatment for patients who cannot tolerate or become refractory to steroid treatment. Steroid nonresponders may benefit from biologic therapy. Alternative treatment modalities including nonsteroidal immunosuppressants and biologics have been studied in small cohorts of patients with varying results. Prospective studies investigating the efficacy of biologic and nonsteroidal therapy are warranted.

LEVEL OF EVIDENCE

2.