Pravastatin Administration Alleviates Kanamycin-Induced Cochlear Injury and Hearing Loss

Lipids and Statin Medication With Sensorineural Hearing Loss: A Mendelian Randomization Study

BACKGROUND

Recent insights suggest that lipids and statin medication play a role in the development of sensorineural hearing loss (SNHL), yet the exact role remains controversial. This research applied Mendelian randomization (MR) to assess whether lipids and statin medication are associated with an increased risk of SNHL.

METHODS

A two-sample MR was used in this study. Genetic instruments were constructed from variants associated with risk factors. Data for lipids and statin medication were obtained from the IEU OpenGWAS project, and for SNHL from the Finngen research project, which comprises 32,487 individuals with SNHL and 331,736 control individuals.

RESULTS

Genetically predicted higher levels of triglycerides were associated with an increased risk of SNHL. The use of genetically predicted atorvastatin was associated with a lower risk of SNHL. Rosuvastatin has demonstrated potential in treating SNHL, yet further investigations are warranted to elucidate its relationship with SNHL. Insufficient evidence was available to suggest that the genetically predicted level of high-density lipoprotein cholesterol or low-density lipoprotein cholesterol or the use of simvastatin were associated with SNHL.

CONCLUSIONS

The study provides genetic evidence suggesting that increased levels of triglycerides in the blood could be a risk factor for SNHL and that the use of certain statin medications, including atorvastatin and rosuvastatin, could reduce the risk of SNHL. These results align with findings from previous observational studies that have linked hyperlipidemia with the risk of SNHL.

LEVEL OF EVIDENCE

According to the Oxford Centre for Evidence-Based Medicine 2011 levels of Evidence, the study has a third level of Evidence Laryngoscope, 2024.

Potential role of modulating autophagy levels in sensorineural hearing loss

In recent years, extensive research has been conducted on the pathogenesis of sensorineural hearing loss (SNHL). Apoptosis and necrosis have been identified to play important roles in hearing loss, but they cannot account for all hearing loss. Autophagy, a cellular process responsible for cell self-degradation and reutilization, has emerged as a significant factor contributing to hearing loss, particularly in cases of autophagy deficiency. Autophagy plays a crucial role in maintaining cell health by exerting cytoprotective and metabolically homeostatic effects in organisms. Consequently, modulating autophagy levels can profoundly impact the survival, death, and regeneration of cells in the inner ear, including hair cells (HCs) and spiral ganglion neurons (SGNs). Abnormal mitochondrial autophagy has been demonstrated in animal models of SNHL. These findings indicate the profound significance of comprehending autophagy while suggesting that our perspective on this cellular process holds promise for advancing the treatment of SNHL. Thus, this review aims to clarify the pathogenic mechanisms of SNHL and the role of autophagy in the developmental processes of various cochlear structures, including the greater epithelial ridge (GER), SGNs, and the ribbon synapse. The pathogenic mechanisms of age-related hearing loss (ARHL), also known as presbycusis, and the latest research on autophagy are also discussed. Furthermore, we underscore recent findings on the modulation of autophagy in SNHL induced by ototoxic drugs. Additionally, we suggest further research that might illuminate the complete potential of autophagy in addressing SNHL, ultimately leading to the formulation of pioneering therapeutic strategies and approaches for the treatment of deafness.

Hear and Now: Ongoing Clinical Trials to Prevent Drug-Induced Hearing Loss

Each year over half a million people experience permanent hearing loss caused by treatment with therapeutic drugs with ototoxic side effects. There is a major unmet clinical need for therapies that protect against this hearing loss without reducing the therapeutic efficacy of these lifesaving drugs. At least 17 clinical trials evaluating 10 therapeutics are currently underway for therapies aimed at preventing aminoglycoside- and/or cisplatin-induced ototoxicity. This review describes the preclinical and clinical development of each of these approaches, provides updates on the status of ongoing trials, and highlights the importance of appropriate outcome measures in trial design and the value of reporting criteria in the dissemination of results.

Effect of statins on hearing outcome in patients with idiopathic sudden sensorineural hearing loss

Objective

Statins have been reported to improve vascular endothelial function and microcirculation, reduce oxidative stress, and exert anti-inflammatory and protective effects against inner ear damage. Therefore, this study aimed to investigate the effect of statins on hearing prognosis in patients with idiopathic sudden sensorineural hearing loss (ISSNHL).

Methods

We reviewed the medical records of 149 patients diagnosed with ISSNHL. Clinical characteristics, hearing thresholds, statin medications, and hematological findings were investigated. First, patients with ISSNHL were assigned to the good and poor outcome groups, and factors influencing their prognosis were analyzed. Furthermore, patients with dyslipidemia were investigated to determine whether statins have therapeutic effects on ISSNHL.

Results

Significant differences in age (p = .011), days from the onset of ISSNHL to the initiation of treatment (p = .04), and hematological total cholesterol (TC; p = .015) between the good and poor outcome groups were observed. Furthermore, when hearing outcomes were investigated in patients with dyslipidemia, TC was significantly lower in the good outcome group (p = .03). Although no significant therapeutic effects of statins were observed in participants with dyslipidemia, patients in the statin-treated group were significantly older and experienced more diabetic complications than those in the non-statin-treated group.

Conclusion

Although our study showed that dyslipidemia is a poor prognostic factor for ISSNHL, statins had no significant therapeutic effects on hearing recovery in ISSNHL patients with dyslipidemia. The patients that received statin medications were significantly older and experienced more diabetic complications, which may have affected their hearing prognosis.

Level of Evidence

Level 4.

Statins protect mice from high-decibel noise-induced hearing loss

No medical interventions for noise induced hearing loss (NIHL) are approved by the Food and Drug Administration (USA). Here, we evaluate statins in CBA/CaJ mice as potential drugs for hearing loss. Direct delivery of fluvastatin to the cochlea and oral delivery of lovastatin were evaluated. Baseline hearing was assessed using Auditory Brain Stem Responses (ABRs). For fluvastatin, a cochleostomy was surgically created in the basal turn of the cochlea by a novel, laser-based procedure, through which a catheter attached to a mini-osmotic pump was inserted. The pump was filled with a solution of 50 µM fluvastatin+carrier or with the carrier alone for continuous delivery to the cochlea. Mice were exposed to one octave band noise (8-16 kHz x 2 h x 110 dB SPL). In our past work with guinea pigs, fluvastatin protected in the contralateral cochlea. In this study in CBA/CaJ mice, hearing was also assessed in the contralateral cochlea 1-4 weeks after noise exposure. At two weeks post exposure, ABR thresholds at 4, 8, 12, 16, and 32 kHz were elevated, as expected, in the noise+carrier alone treated mice by approximately 9-, 17-, 41-, 29-, and 34-dB, respectively. Threshold elevations were smaller in mice treated with noise+fluvastatin to about 2-, 6-, 20-,12- and 12-dB respectively. Survival of inner hair cell synapses were not protected by fluvastatin over these frequencies. Lovastatin delivered by gavage showed lower threshold shifts than with carrier alone. These data show that direct and oral statin delivery protects mice against NIHL.