Modulation of Gut Microbiome as a Therapeutic Modality for Auditory Disorders

The gut microbiome has been shown to play a pivotal role in health and disease. Recently, there has been increased interest within the auditory community to explore the role of the gut microbiome in the auditory system and its implications for hearing disorders such as sensorineural hearing loss (SNHL), otitis media, and tinnitus. Studies have suggested that modulating the gut microbiome using probiotics as well as with diets high in monounsaturated and omega-3 fatty acids is associated with a reduction in inflammation prevalence in auditory disorders. This review aims to evaluate the current literature on modulation of the gut microbiome and its effects on otological conditions. The probiotic conversion of nondigestible carbohydrates into short-chain fatty acids has been shown to provide benefits for improving hearing by maintaining an adequate vascular supply. For acute and secretory otitis media, studies have shown that a combination therapy of probiotics with a decreased dose of antibiotics yields better clinical outcomes than aggressive antibiotic treatment alone. Gut microbiome modulation also alters neurotransmitter levels and reduces neuroinflammation, which may provide benefits for tinnitus by preventing increased neuronal activity. Further studies are warranted to evaluate the efficacy of probiotics, natural health products, and micronutrients on auditory disorders, paving the way to develop novel interventions.

Recent Advancements in Understanding the Gut Microbiome and the Inner Ear Axis

The gut microbiome and its dynamic association with organ systems beyond the gastrointestinal tract, such as the nervous and cardiovascular systems, is an emerging area of research. Although the role of the gut microbiome has been extensively characterized in the gut-brain axis, the implications of gut dysbiosis in inner ear inflammation and hearing deficits have still not been explored. With some similarities outlined between the blood-brain barrier (BBB) and the blood labyrinth barrier (BLB) of the inner ear, this review aims to explore the axis between the gut microbiome and the inner ear as it pertains to their bidirectional communication.

Advancements in Stem Cell Technology and Organoids for the Restoration of Sensorineural Hearing Loss

BACKGROUND

 Sensorineural hearing loss (SNHL) is a significant cause of morbidity worldwide and currently has no curative treatment. Technological advancements in stem cell therapy have led to numerous studies that examine the generation of otic sensory cells from progenitors to restore inner ear function. Recently, organoids have emerged as a promising technique to further advance the process of creating functional replacement cells after irreversible hearing loss. Organoids are the three-dimensional generation of stem cells in culture to model the tissue organization and cellular components of the inner ear. Organoids have emerged as a promising technique to create functioning cochlear structures in vitro and may provide crucial information for the utilization of stem cells to restore SNHL.

PURPOSE

 The purpose of this review is to discuss the recent advancements in stem cell-based regenerative therapy for SNHL.

RESULTS

 Recent studies have improved our understanding about the developmental pathways involved in the generation of hair cells and spiral ganglion neurons. However, significant challenges remain in elucidating the molecular interactions and interplay required for stem cells to differentiate and function as otic sensory cells. A few of the challenges encountered with traditional stem cell therapy may be addressed with organoids.

CONCLUSION

 Stem cell-based regenerative therapy holds a great potential for developing novel treatment modalities for SNHL. Further advancements are needed in addressing the challenges associated with stem cell-based regenerative therapy and promote their translation from bench to bedside.