Blood Prestin Levels in Normal Hearing and in Sensorineural Hearing Loss: A Scoping Review

Prestin in Human Perilymph, Cerebrospinal Fluid, and Blood as a Biomarker for Hearing Loss

OBJECTIVE

Determining the concentration of prestin in human blood, cerebrospinal fluid (CSF), and perilymph (PL), and evaluating its suitability as a clinical biomarker for sensori-neural hearing loss (SNHL).

STUDY DESIGN

Human blood, CSF, and PL samples were intraoperatively collected from 42 patients with tumors of the internal auditory canal or with intracochlear tumors undergoing translabyrinthine or middle fossa tumor removal. Prestin concentration was measured using enzyme-linked immunosorbent assay and linear regression analyses were performed to investigate its associations with audiological as well as vestibular test results.

SETTING

Tertiary referral center.

RESULTS

The median prestin concentration in blood samples of the 42 study participants (26 women, mean ± standard deviation age, 52.7 ± 12.5 years) was 1.32 (interquartile range, IQR, 0.71-1.99) ng/mL. CSF prestin levels were significantly higher with 4.73 (IQR, 2.45-14.03) ng/mL (P = .005). With 84.74 (IQR, 38.95-122.00) ng/mL, PL prestin concentration was significantly higher compared to blood (P = .01) and CSF (P = .03) levels. Linear regression analyses showed significant associations of CSF prestin concentration with preoperative hearing levels (pure-tone average and word recognition; P = .008, R2 = 0.1894; P = .03, R2 = 0.1857), but no correlations with blood or PL levels.

CONCLUSION AND RELEVANCE

This study's findings highlight the volatile nature of prestin levels and provide the first insights into this potential biomarker's concentrations in body fluids apart from blood. Future investigations should comprehensively assess human prestin levels with different etiologies of SNHL, prestin's natural homeostasis and systemic circulation, and its temporal dynamics after cochlear trauma. Finally, clinically approved detection kits for prestin are urgently required prior to considering a potential translational implementation of this diagnostic technique.

Serum Prestin and Otolin-1 Levels in Pilots of Helicopter-Based Emergency Medical Services: Potential Markers for Ear Injury

INTRODUCTION

Occupational noise exposure is a major public health concern, impacting a large workforce worldwide. In this study, we sought to evaluate the serum concentrations of prestin, a cochlear protein that diminishes following noise exposure, and otolin-1, a protein secreted into the bloodstream subsequent to inner ear damage, among three diverse professional categories, each exposed to varying degrees of noise. Helicopter emergency medical service (HEMS) pilots and construction workers were considered high-risk groups due to their elevated exposure to occupational noise, whereas office workers were regarded as a low-risk group, reflecting their comparatively minimal noise exposure.

METHODS

The study sample included 60 males, encompassing helicopter pilots, construction laborers, and office workers (n=20, each). Recruitment occurred during standard occupational health visits, with all participants presenting normal clinical audiograms. Serum levels of prestin and otolin-1 were measured in duplicate using commercially available immunoassays and compared across the three professional categories.

RESULTS

HEMS pilots had the lowest mean serum prestin level at 211±27 pg/mL, followed by construction workers at 234±29 pg/mL, and office workers at 269±42 pg/mL (p<0.001, one-way analysis of variance), with all inter-group differences statistically significant (p<0.05, Tukey's post hoc tests). For otolin-1, HEMS pilots showed the highest mean at 216±20 pg/mL, with construction workers at 196±22 pg/mL, and office workers at 181±20 pg/mL (p<0.001, one-way analysis of variance). Statistically significant differences were found between HEMS pilots and both other groups for otolin-1 levels (p<0.05, Tukey's post hoc tests), but not between construction workers and office workers.

CONCLUSIONS

 Serum concentrations of prestin and otolin-1 may differ among healthy individuals according to their occupational noise exposure and have the potential to act as indicators of subclinical inner ear injury. To substantiate these preliminary observations, incorporating exposure assessment, especially via direct measurements of noise and vibration exposure, would markedly improve the reliability of our findings.

Association between air pollution and sudden sensorineural hearing loss (SSHL): A systematic review and meta-analysis

Recent studies have indicated that air pollution (AP) has harmful effects on hearing and ear diseases such as Sudden Sensorineural Hearing Loss (SSHL). The purpose of this study was to evaluate the impact of exposure to AP on SSHL incidence. Valid electronic databases were searched to retrieve studies published until December 1, 2022, using appropriate keywords. The result of the search was 1146 studies, and after screening according to the defined criteria, in total 8 studies were obtained. The risk of bias (ROB) in the studies and their quality were assessed. Finally, the meta-analysis with a significance level of 5% was performed. The findings revealed that the mean level of SO2, CO, NO2, and PM10 in the patient group was more than that of the control group, and p-values were 0.879, 0.144, 0.077, and 0.138, respectively. There was an indirect relation between air pollutants and SSHL, and PM2.5 showed a significant effect (p < 0.05). Given the limited research and the use of different statistical methods, more research is suggested to confirm this association and to determine the mechanisms by which AP exposure may cause SSHL.

Automated Western Blot Analysis of Ototoxin-Induced Prestin Burst in the Blood after Cyclodextrin Exposure

HYPOTHESIS

Ototoxin cyclodextrin (CDX) will induce a burst in serum prestin when quantified with automated Western blot analysis.

BACKGROUND

In the clinical realm, we primarily rely on audiological measures for diagnosis and surveillance of sensorineural hearing loss (SNHL) and have limited therapeutic options. We have proposed a blood-based biomarker approach to overcome this challenge by measuring the outer hair cell's (OHC) electromotile protein, prestin, in the blood. Previously, we demonstrated a burst in serum prestin after cisplatin exposure using enzyme-linked immunosorbent assayELISA.

METHODS

Guinea pigs were treated with either 3,000 or 4,000 mg/kg CDX, and serum samples were obtained through 3 days after exposure. Serum prestin levels were quantified using automated blot analysis, western and hair cell counts were obtained.

RESULTS

Both 3,000 and 4,000 mg/kg resulted in robust OHC loss, although more variability was seen at the lower dose. Automated Western blot analysis demonstrated that the prestin profile after CDX exposure is different than baseline. Specifically, a new ~134- kDa band accounted for the prestin burst after ototoxin ablation of OHCs at both doses.

CONCLUSIONS

We reproduced the prestin burst seen after cisplatin administration using CDX. Automated Western blot western analysis revealed that a ~a ~ 134- kDa species of prestin is responsible for the burst. We suggest that the induced band may be a prestin dimer, which could serve as a biomarker for early detection of ototoxicity in the clinical setting. These results add further promise to the potential of serum prestin to serve as an ototoxicity biomarker when using therapeutics with ototoxic properties.

Evaluation of the relationship between prestin serum biomarker and sensorineural hearing loss: a case-control study

RESEARCH BACKGROUND AND AIM

There is not any routine serum biomarker for diagnosing hearing loss (HL). An inner ear-specific protein, prestin can be measured as a serum biochemical marker for HL diagnosis. The present study investigates, for the first time, the relationship between prestin serum levels and sensorineural HL (SNHL) in an Iranian population.

MATERIALS AND METHODS

In this case-control study, 176 samples were examined in four groups including two control and two SNHL groups of 20-50 and ≥ 50 years with different severities of SNHL. Plasma prestin concentration was measured using Human Prestin (SLC26A5) ELISA Kit. Data analysis was conducted using SPSS v.23 with level of significance as 0.05.

RESULTS

Groups with SNHL had higher prestin levels (Mean = 182.29, SD = 71.24) compared to the control groups (Mean = 122.50, SD = 57.1) (P < 0.001). Results of the multinomial logistic regression of relationship between prestin level and SNHL remained significant after controlling intervening variables (P < 0.001 and odds ratio = 1.017 and 95% CI OR: 1.01-1.024). Results of the ordinal logistic regression model revealed that prestin level was significantly associated with the degree of HL (P < 0.001 and Odds ratio = 1.009 and 95% CI and OR: 1.005-1.013), so that the likelihood of HL increased with the rise in prestin levels. The best cutoff point for the 20-50 group was the prestin content of 132.5 pg/ml (sensitivity: 75%, specificity: 70.05%), while for the group of ≥ 50 was as 130 pg/ml (sensitivity: 84.1%, specificity: 68.2%).

CONCLUSIONS

Results of the present study revealed that prestin acts as a valuable biomarker for SNHL.

Integrating pharmacogenomics into clinical trials of hearing disorders

In 2019, the U.S. Food and Drug Administration issued guidance to increase the efficiency of drug development and support precision medicine, including tailoring treatments to those patients who will benefit based on genetic variation even in the absence of a documented mechanism of action. Although multiple advancements have been made in the field of pharmacogenetics (PGx) for other disease conditions, there are no approved PGx guidelines in the treatment of hearing disorders. In studies of noise-induced hearing loss (NIHL), some progress has been made in the last several years associating genomic loci with susceptibility to noise damage. However, the power of such studies is limited as the underlying physiological responses may vary considerably among the patient populations. Here, we have summarized previous animal studies to argue that NIHL subtyping is a promising strategy to increase the granularity of audiological assessments. By coupling this enhanced phenotyping capability with genetic association studies, we suggest that drug efficacy will be better predicted, increasing the likelihood of success in clinical trials when populations are stratified based on genetic variation or designed with multidrug combinations to reach a broader segment of individuals suffering or at risk from NIHL.

Noise exposure levels predict blood levels of the inner ear protein prestin

Serological biomarkers of inner ear proteins are a promising new approach for studying human hearing. Here, we focus on the serological measurement of prestin, a protein integral to a human’s highly sensitive hearing, expressed in cochlear outer hair cells (OHCs). Building from recent nonhuman studies that associated noise-induced OHC trauma with reduced serum prestin levels, and studies suggesting subclinical hearing damage in humans regularly engaging in noisy activities, we investigated the relation between serum prestin levels and environmental noise levels in young adults with normal clinical audiograms. We measured prestin protein levels from circulating blood and collected noise level data multiple times over the course of the experiment using body-worn sound recorders. Results indicate that serum prestin levels have a negative relation with noise exposure: individuals with higher routine noise exposure levels tended to have lower prestin levels. Moreover, when grouping participants based on their risk for a clinically-significant noise-induced hearing loss, we found that prestin levels differed significantly between groups, even though behavioral hearing thresholds were similar. We discuss possible interpretations for our findings including whether lower serum levels may reflect subclinical levels of OHC damage, or possibly an adaptive, protective mechanism in which prestin expression is downregulated in response to loud environments.