Adiponectin deficiency exacerbates age-related hearing impairment

Chronic β3 adrenergic agonist treatment improves brain microvascular endothelial function and cognition in aged mice

Microvascular endothelial dysfunction, characterized by impaired neurovascular coupling, reduced glucose uptake, blood-brain barrier disruption, and microvascular rarefaction, plays a critical role in the pathogenesis of age-related vascular cognitive impairment (VCI). Emerging evidence points to non-cell autonomous mechanisms mediated by adverse circulating milieu (an increased ratio of pro-geronic to anti-geronic circulating factors) in the pathogenesis of endothelial dysfunction leading to impaired cerebral blood flow and cognitive decline in the aging population. In particular, age-related adipose dysfunction contributes, at least in part, to an unfavorable systemic milieu characterized by chronic hyperglycemia, hyperinsulinemia, dyslipidemia, and altered adipokine profile, which together contribute to microvascular endothelial dysfunction. Hence, in the present study, we aimed to test whether thermogenic stimulation, an intervention known to improve adipose and systemic metabolism by increasing cellular energy expenditure, could mitigate brain endothelial dysfunction and improve cognition in the aging population. Eighteen-month-old old C57BL/6J mice were treated with saline or CL (β3-adrenergic agonist) for 6 weeks followed by functional analysis to assess endothelial function and cognition. CL treatment improved neurovascular coupling responses and rescued brain glucose uptake in aged animals. In addition, CL treatment also attenuated blood-brain barrier leakage and associated neuroinflammation in the cortex of aged animals. More importantly, these beneficial changes in microvascular function translated to improved cognitive performance in radial arm water maze and Y-maze tests. Our results suggest that β3-adrenergic agonist treatment improves multiple aspects of brain microvascular endothelial function and can be potentially repurposed for treating age-associated cognitive decline.

The inflammatory and metabolic status of patients with sudden-onset sensorineural hearing loss

Introduction

Sudden sensorineural hearing loss (SSNHL) is a common emergency symptom in otolaryngology that requires immediate diagnosis and treatment. SSNHL has a multifactorial etiology, and its pathophysiologic mechanisms may be associated with inflammatory and metabolic changes that may affect the cochlear microenvironment or its nervous component, thus triggering the process or hindering hearing recovery. Therefore, the aim of this study was to assess metabolic and inflammatory changes to identify systemic parameters that could serve as prognostic factors for hearing recovery in patients with SSNHL.

Materials and methods

Thirty patients with a sudden hearing loss of at least 30 dB in three contiguous frequencies were enrolled in this study. Patients were followed up for 4 months and peripheral blood samples were collected at 7 days (V1), 30 days (V2) and 120 days (V3). Interleukins (IL)-1F7, IL-2, IL-4, IL-5, IL-6, IL-10, interferon γ (IFN-γ), tumor necrosis factor α (TNF-α) and adiponectin were quantified in serum. In addition, lipid and glycemic profiles as well as concentration of creatinine, uric acid, fructosamine, peroxide, total proteins and albumin were analyzed. Patients underwent weekly ear-specific hearing tests with standard pure tone thresholds for frequencies of 250-8,000 Hz, speech recognition threshold and word recognition score.

Results

Patients with SSNHL were divided into a group of patients who did not achieve hearing recovery (n = 14) and another group who achieved complete and significant recovery (n = 16). Most serologic parameters showed no significant changes or values indicating clinical changes. However, IFN-γ levels decreased by 36.3% between V1 and V2. The cytokine TNF-α showed a statistically significant decrease from V1 to V3 (from 22.91 to 10.34 pg./mL). Adiponectin showed a decrease from 553.7 ng/mL in V1 to 454.4 ng/mL in V3.

Discussion

Our results show that serologic cytokine levels change in the acute phase of manifestation of SSNHL and establish a parallel between systemic changes and improvements in hearing, especially TNF-α, which showed differences in hearing recovery. The use of IFN-γ, TNF-α and adiponectin may elucidate the clinical improvement in these patients.

The Role of Metabolic Syndrome Components in Sensorineural Hearing Loss in Adolescents: A Case-Control Study

Introduction  Metabolic syndrome (MetS) and its associated components were reported as a possible cause of inner ear dysfunction. However, research about the influence of cardiovascular risk factors on hearing thresholds are conducted mainly in adult patients. Objective  The aim of the present study was to investigate auditory function in adolescents with MetS compared with healthy controls. Methods  One hundred adolescents with metabolic syndrome and 200 sex- and age-matched controls were recruited from a university pediatric endocrine clinic from May 2018 to July 2020. Hearing loss was defined as hearing level ≥ 15 dB at speech frequency (SFHL) or high frequency (HFHL) in one or both ears. A multivariable conditional logistic regression analysis examined the correlation between MetS components and several important demographic characteristics, and hearing loss. Results  A total of 165 (55.0%) boys and 135 (45.0%) girls participated in this study. The rates of SFHL and HFHL in adolescents with MetS were 32.0% and 51.0%, respectively. Those values for controls were 5.0% and 15.5%, respectively. The regression analysis showed high triglycerides as a significant predictor for SFHL (odds ratio 10.87; 95% confidence interval: 1.98, 59.74). Neither predictor of interest was significant for HFHL. Conclusion  Hypertriglyceridemia may be an important factor in the pathogenesis of SFHL. However, the strength of the association was not significant with a wide confidence interval. Also, we were unable to find an association between predictors and HFHL with the current sample size. Larger and prospective studies are recommended.

Sex differences in hearing impairment due to diet-induced obesity in CBA/Ca mice

BACKGROUND

Obesity is an independent risk factor for hearing loss. Although attention has focused on major obesity comorbidities such as cardiovascular disease, stroke, and type 2 diabetes, the impact of obesity on sensorineural organs, including the auditory system, is unclear. Using a high-fat diet (HFD)-induced obese mouse model, we investigated the impact of diet-induced obesity on sexual dimorphism in metabolic alterations and hearing sensitivity.

METHODS

Male and female CBA/Ca mice were randomly assigned to three diet groups and fed, from weaning (at 28 days) to 14 weeks of age, a sucrose-matched control diet (10 kcal% fat content diet), or one of two HFDs (45 or 60 kcal% fat content diets). Auditory sensitivity was evaluated based on the auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and ABR wave 1 amplitude at 14 weeks of age, followed by biochemical analyses.

RESULTS

We found significant sexual dimorphism in HFD-induced metabolic alterations and obesity-related hearing loss. Male mice exhibited greater weight gain, hyperglycemia, increased ABR thresholds at low frequencies, elevated DPOAE, and lower ABR wave 1 amplitude compared to female mice. The hair cell (HC) ribbon synapse (CtBP2) puncta showed significant sex differences. The serum concentration of adiponectin, an otoprotective adipokine, was significantly higher in female than in male mice; cochlear adiponectin levels were elevated by HFD in female but not male mice. Adiponectin receptor 1 (AdipoR1) was widely expressed in the inner ear, and cochlear AdipoR1 protein levels were increased by HFD, in female but not male mice. Stress granules (G3BP1) were significantly induced by the HFD in both sexes; conversely, inflammatory (IL-1β) responses were observed only in the male liver and cochlea, consistent with phenotype HFD-induced obesity.

CONCLUSIONS

Female mice are more resistant to the negative effects of an HFD on body weight, metabolism, and hearing. Females showed increased peripheral and intra-cochlear adiponectin and AdipoR1 levels, and HC ribbon synapses. These changes may mediate resistance to HFD-induced hearing loss seen in female mice.

The influence of metabolic syndrome on age-related hearing loss from the perspective of mitochondrial dysfunction

With the increase in life expectancy in the global population, aging societies have emerged in many countries, including China. As a common sensory defect in the elderly population, the prevalence of age-related hearing loss and its influence on society are increasing yearly. Metabolic syndrome is currently one of the main health problems in the world. Many studies have demonstrated that metabolic syndrome and its components are correlated with a variety of age-related diseases of the peripheral sensory system, including age-related hearing loss. Both age-related hearing loss and metabolic syndrome are high-prevalence chronic diseases, and many people suffer from both at the same time. In recent years, more and more studies have found that mitochondrial dysfunction occurs in both metabolic syndrome and age-related hearing loss. Therefore, to better understand the impact of metabolic syndrome on age-related hearing loss from the perspective of mitochondrial dysfunction, we reviewed the literature related to the relationship between age-related hearing loss and metabolic syndrome and their components to discern the possible role of mitochondria in both conditions.

Obesity-induced cognitive impairment in older adults: a microvascular perspective

Over two-thirds of individuals aged 65 and older are obese or overweight in the United States. Epidemiological data show an association between the degree of adiposity and cognitive dysfunction in the elderly. In this review, the pathophysiological roles of microvascular mechanisms, including impaired endothelial function and neurovascular coupling responses, microvascular rarefaction, and blood-brain barrier disruption in the genesis of cognitive impairment in geriatric obesity are considered. The potential contribution of adipose-derived factors and fundamental cellular and molecular mechanisms of senescence to exacerbated obesity-induced cerebromicrovascular impairment and cognitive decline in aging are discussed.

Obesity as a Possible Risk Factor for Pediatric Sensorineural Hearing Loss

OBJECTIVES/HYPOTHESIS

Childhood hearing loss impacts linguistic, academic, social, and psychologic development, and may have lasting implications for future workforce performance. Current evidence for obesity as a pediatric sensorineural hearing loss (SNHL) risk factor is intriguing but equivocal. We hypothesized that obesity is associated with a higher risk of SNHL. We additionally examined whether underweight is associated with a higher risk of SNHL.

STUDY DESIGN

Retrospective database review.

METHODS

A single-institution audiologic database from 2015 to 2020 was queried for audiograms with type-A tympanograms from children aged 5 to 18 years old. Comorbidities known to be associated with hearing loss were excluded. We then examined both for sub-clinical (≥15 dB) high- or low-frequency hearing loss, and for clinical (≥21 dB) hearing loss, with the aim of examining the association between obesity and SNHL. Multivariable logistic regression was performed to adjust for age, gender, diabetes mellitus, attention deficit hyperactivity disorder, and autism.

RESULTS

A total of 3,142 children were included. Obesity was not associated with risk of SNHL (adjusted OR 0.82; 95% CI: 0.60, 1.12). Underweight children had a higher risk of SNHL than normal weight children (adjusted OR 1.78; 95% CI: 1.08, 2.95). Autism was significantly associated with increased risk of sub-clinical SNHL only (adjusted OR 2.00; 95% CI 1.34, 2.98).

CONCLUSIONS

No association was found between obesity and pediatric SNHL. Underweight children may represent a higher-risk population for SNHL. There appears to be an increasing risk of SNHL as children approach adolescence. Further study of systemic risk factors for SNHL is indicated.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:1416-1419, 2021.

Antioxidant Therapy against Oxidative Damage of the Inner Ear: Protection and Preconditioning

Oxidative stress is an important mechanism underlying cellular damage of the inner ear, resulting in hearing loss. In order to prevent hearing loss, several types of antioxidants have been investigated; several experiments have shown their ability to effectively prevent noise-induced hearing loss, age-related hearing loss, and ototoxicity in animal models. Exogenous antioxidants has been used as single therapeutic agents or in combination. Antioxidant therapy is generally administered before the production of reactive oxygen species. However, post-exposure treatment could also be effective. Preconditioning refers to the phenomenon of pre-inducing a preventative pathway by subtle stimuli that do not cause permanent damage in the inner ear. This renders the inner ear more resistant to actual stimuli that cause permanent hearing damage. The preconditioning mechanism is also related to the induction of antioxidant enzymes. In this review, we discuss the mechanisms underlying antioxidant-associated therapeutic effects and preconditioning in the inner ear.

Body mass index, waist circumference, and risk of hearing loss: a meta-analysis and systematic review of observational study

BACKGROUND

Emerging evidence implicates excess weight as a potential risk factor for hearing loss. However, this association remained inconclusive. Therefore, we aimed to systematically and quantitatively review the published observational study on the association between body mass index (BMI) or waist circumference (WC) and hearing loss.

METHODS

The odds ratios (ORs) or relative risks (RRs) with their 95% confidence intervals (CIs) were pooled under a random-effects model. Fourteen observational studies were eligible for the inclusion in the final analysis.

RESULTS

In the meta-analysis of cross-sectional studies, the ORs for prevalent hearing loss were 1.10 (95% CI 0.88, 1.38) underweight, 1.14 (95% CI 0.99, 1.32) for overweight, OR 1.40 (95% CI 1.14, 1.72) for obesity, 1.14 (95% CI 1.04, 1.24) for each 5 kg/m2 increase in BMI, and 1.22 (95% CO 0.88. 1.68) for higher WC. In the meta-analysis of longitudinal studies, the RRs were 0.96 (95% CI 0.52, 1.79) for underweight, 1.15 (95% CI 1.04, 1.27) for overweight, 1.38 (95% CI 1.07, 1.79) for obesity, 1.15 (95% CI 1.01, 1.30) for each 5 kg/m2 increase in BMI, and 1.11 (95% CI 1.01, 1.22) for higher WC.

CONCLUSIONS

In summary, our findings add weight to the evidence that elevated BMI and higher WC may be positively associated with the risk of hearing loss.

Can Nutritional Intervention for Obesity and Comorbidities Slow Down Age-Related Hearing Impairment?

BACKGROUND

Age-related hearing impairment (ARHI), the most common sensory deficit in the elderly, is associated with enormous social and public health burdens. Emerging evidence has suggested that obesity and comorbidities might increase the risk of ARHI. However, no reviews have been published that address the role of nutritional interventions for obesity and comorbidities in the prevention of ARHI.

METHODS

A PubMed database search was conducted to identify the relationship between obesity and ARHI. "Obesity", "metabolic syndrome", "adipose-derived hormone", "fatty acid", and "age-related hearing impairment" were included as keywords.

RESULTS

A total of 89 articles was analyzed with 39 articles of relevance to ARHI. A high-fat diet may induce oxidative stress, mitochondrial damage, and apoptosis in the inner ear. Statins have been shown to delay the progression of ARHI by improving the lipid profile, reducing oxidative stress, and inhibiting endothelial inflammation. Aldosterone could exert protective effects against ARHI by upregulating the Na-K-2Cl co-transporter 1 in the cochlea. Omega-3 polyunsaturated fatty acids could preserve the cochlear microcirculation by reducing dyslipidemia and inhibiting inflammation. Alpha-lipoic acid and lecithin might delay the progression of ARHI by protecting cochlear mitochondrial DNA from damage due to oxidative stress. Tea and ginseng might protect against ARHI through their anti-obesity and anti-diabetic effects.

CONCLUSIONS

Nutritional interventions for obesity and comorbidities, including a low-fat diet, supplementation with statins, aldosterone, omega-3 polyunsaturated fatty acids, alpha-lipoic acids, lecithin, tea, and ginseng, may protect against the development of ARHI.

Hearing loss in humans drinking tube well water with high levels of iron in arsenic-polluted area

Well water for drinking with increased levels of iron in arsenic-polluted areas has been reported worldwide. Oral exposure to arsenic has been shown to be associated with hearing loss, while there is no evidence for an association between excessive exposure to iron and hearing loss in humans. In this study, we determined iron and arsenic levels in biological samples and hearing levels by pure tone audiometry (PTA) in subjects in a control area and an arsenic-polluted area in Bangladesh. The iron level in well water in the arsenic-polluted area was significantly higher than that in piped supply water in the control area. Subjects in the polluted area (n = 109), who had higher iron and arsenic levels in hair and toenails than those in subjects in the control area (n = 36), had an increased risk of hearing loss at 8 kHz and 12 kHz after adjustments for age, gender, smoking and BMI. Significant associations of the exposure group with hearing loss at 8 kHz and 12 kHz remained after further adjustment for arsenic levels in toenails and hair. Thus, this pilot study showed that excessive exposure to iron via drinking water is a potential risk for hearing loss in humans.

Purinergic Signaling and Cochlear Injury-Targeting the Immune System?

Hearing impairment is the most common sensory deficit, affecting more than 400 million people worldwide. Sensorineural hearing losses currently lack any specific or efficient pharmacotherapy largely due to the insufficient knowledge of the pathomechanism. Purinergic signaling plays a substantial role in cochlear (patho)physiology. P2 (ionotropic P2X and the metabotropic P2Y) as well as adenosine receptors expressed on cochlear sensory and non-sensory cells are involved mostly in protective mechanisms of the cochlea. They are implicated in the sensitivity adjustment of the receptor cells by a K⁺ shunt and can attenuate the cochlear amplification by modifying cochlear micromechanics. Cochlear blood flow is also regulated by purines. Here, we propose to comprehend this field with the purine-immune interactions in the cochlea. The role of harmful immune mechanisms in sensorineural hearing losses has been emerging in the horizon of cochlear pathologies. In addition to decreasing hearing sensitivity and increasing cochlear blood supply, influencing the immune system can be the additional avenue for pharmacological targeting of purinergic signaling in the cochlea. Elucidating this complexity of purinergic effects on cochlear functions is necessary and it can result in development of new therapeutic approaches in hearing disabilities, especially in the noise-induced ones.

Association of Obesity with Hearing Impairment in Adolescents

Hearing loss (HL) is the third most common chronic physical condition in the United States. Obesity has become an increasingly important public health concern, as the prevalence in children, adolescents and adults has increased over the past few decades. The objectives of this study is to investigate whether obesity is associated with audiometric notches indicative of noise-induced hearing loss (NIHL), speech frequency hearing loss (SFHL), and high frequency hearing loss (HFHL) in adolescent participants of the National Health and Nutrition Examination Survey 2007–2010. The prevalence of overall audiometric notches in the adolescent population was 16.0% with higher prevalence in females than males. The prevalence of SFHL and HFHL were higher in males than females (SFHL, 7.3% vs. 5.4%, respectively; and HFHL 14.3% vs. 8.1%, respectively). Obese adolescents had a higher adjusted OR to have audiometric notches (OR = 1.93; 95% CI: 1.33–2.81) and HFHL (OR = 1.95; 95% CI: 1.19–3.21). Continued preventative efforts towards reducing obesity might also help to reduce the risk for HL and NIHL.

Purinergic signaling in the organ of Corti: Potential therapeutic targets of sensorineural hearing losses

Purinergic signaling is deeply involved in the development, functions and protective mechanisms of the cochlea. Release of ATP and activation of purinergic receptors on sensory and supporting/epithelial cells play a substantial role in cochlear (patho)physiology. Both the ionotropic P2X and the metabotropic P2Y receptors are widely distributed on the inner and outer hair cells as well as on the different supporting cells in the organ of Corti and on other epithelial cells in the scala media. Among others, they are implicated in the sensitivity adjustment of the receptor cells by a K⁺ shunt and can attenuate the cochlear amplification by modifying cochlear micromechanics acting on outer hair cells and supporting cells. Cochlear blood flow is also regulated by purines. Sensorineural hearing losses currently lack any specific or efficient pharmacotherapy. Decreasing hearing sensitivity and increasing cochlear blood supply by pharmacological targeting of purinergic signaling in the cochlea are potential new therapeutic approaches in these hearing disabilities, especially in the noise-induced ones.

The Association Between Age-Related Hearing Impairment and Metabolic Syndrome in Korean Women: 5-Year Follow-Up Observational Study

BACKGROUND

Although several observational studies showed a relationship between various conditions of metabolic syndrome (MetS) and hearing threshold, there are no studies about longitudinal audiometric results related MetS. The aim of this study was to investigate the association between MetS and age-related hearing impairment (ARHI) through a large, average 5-year longitudinal follow-up, clinical comparative analysis.

MATERIALS AND METHODS

We recruited 1381 women older than 50 years who were enrolled in 2007 and reevaluated in 2012. They had normal or symmetrical sensorineural hearing loss. For the evaluation of the independent impact of MetS on hearing, multivariate analysis was used.

RESULTS

The average follow-up period was 5.0 ± 0.2 years. Subjects with MetS had higher hearing thresholds than subjects without MetS. The loss in high-frequency hearing (≥2000 Hz) progressed more rapidly in women with MetS over a 5-year period.

CONCLUSION

Our analysis using longitudinal and large data revealed that MetS is associated with ARHI in women 50 years and older. High-frequency hearing loss tended to be greater in women with MetS than in those without MetS at the 5-year follow-up. Therefore, older women with MetS should be followed up closely for hearing evaluation.

Adiponectin promotes human jaw bone marrow mesenchymal stem cell chemotaxis via CXCL1 and CXCL8

Adiponectin (APN) is known to promote the osteogenic differentiation of human jaw bone marrow mesenchymal stem cells (h‐JBMMSCs). However, the underlying mechanism has not been fully elucidated. Previously, we showed that APN could promote h‐JBMMSC osteogenesis via APPL1‐p38 by up‐regulating osteogenesis‐related genes. Here, we aimed to determine whether APN could promote h‐JBMMSC chemotaxis through CXCL1/CXCL8. The CCK‐8, wound healing and transwell assays were used to evaluate the proliferation, migration and chemotaxis of h‐JBMMSCs with or without APN treatment. Chemotaxis‐related genes were screened using RNA‐seq, and the results were validated using real‐time PCR and ELISA. We also performed Western blot using the AMPK inhibitor, WZ4003, and the p38 MAPK inhibitor, SB203580, to identify the signalling pathway involved. We found that APN could promote h‐JBMMSC chemotaxis in the co‐culture transwell system. CXCL1 and CXCL8 were screened and confirmed as the up‐regulated target genes. The APN‐induced CXCL1/8 up‐regulation to promote chemotaxis could be blocked by CXCR2 inhibitor SB225002. Western blot revealed that the phosphorylation of AMPK and p38 MAPK increased in a time‐dependent manner with APN treatment. Additionally, WZ4003 and SB203580 could suppress the APN‐induced overexpression of CXCL1 and CXCL8. The results of the transwell chemotaxis assay also supported the above results. Our data suggest that APN can promote h‐JBMMSC chemotaxis by up‐regulating CXCL1 and CXCL8.

Adiponectin reduces ER stress-induced apoptosis through PPARα transcriptional regulation of ATF2 in mouse adipose

Adiponectin is a cytokine produced predominantly by adipose tissue and correlates with glucose and lipid homeostasis. However, the effects of adiponectin on endoplasmic reticulum (ER) stress and apoptosis of adipose tissue remain elusive. In this study, we found that tunicamycin-induced ER stress increased serum free fatty acid (FFA) and impaired glucose tolerance, elevated the mRNA levels of GRP78, Chop, ATF2 and caspase 3, but reduced adiponectin mRNA level in white adipose tissue. Moreover, ER stress-triggered adipocyte apoptosis by increasing cellular FFA level and Ca²⁺ level. Further analysis revealed that adiponectin alleviated ER stress-induced adipocyte apoptosis by elevating peroxisome proliferator-activated receptor alpha (PPARα) mRNA level. Our data also confirmed that adiponectin reduced early apoptotic cells and blocked the mitochondrial apoptosis pathway by activating the AdipoR1/AMP-activated protein kinase (AMPK) signal pathway. In addition, PPARα bound to ATF2 promoter region and inhibited transcription of ATF2. The inhibition of adipocyte apoptosis by adiponectin was correlated with transcriptional suppression of ATF2. Furthermore, adiponectin inhibited ER stress-induced apoptosis by activating the AMPK/PKC pathway. In summary, our data demonstrate adiponectin inhibited ER stress and apoptosis of adipocyte in vivo and in vitro by activating the AMPK/PPARα/ATF2 pathway. Our study establishes that adiponectin is an important adipocytokine for preventing and treating obesity.

Investigation of the ototoxicity of gadoteridol (ProHance) and gadodiamide (Omniscan) in mice

CONCLUSION

In the mouse, when a tympanic perforation is present, gadoteridol does not seem to cause ototoxicity. Gadodiamide may cause mild ototoxicity other than toxicity to the outer hair cells of the cochlea.

OBJECTIVES

Endolymphatic hydrops have been visualized through intra-tympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. However, reports on the safety of GBCAs are limited. This study aimed to assess ototoxicity of gadoteridol and gadodiamide.

METHOD

In a prospective, randomized, controlled trial, myringotomies in the left ear were performed in 20 male C57 BL/6 mice. After testing the baseline auditory brainstem response (ABR) (range = 8-32 kHz), the test solution (gadoteridol, gadodiamide, saline, or cisplatin) was injected into the left ear. ABR testing was repeated 14 days after test solution application. In morphological experiments, images of post-mortem surface preparations were assessed for cochlear hair cell status.

RESULTS

At 14 days following gadoteridol application, there was no significant change in ABR thresholds at 8, 16, or 32 kHz. Gadodiamide application caused a significant change in the ABR threshold at 8 kHz. Apparent cochlear hair cell loss was not observed in the surface preparation after gadoteridol or gadodiamide application.

Is Body Mass Index Associated With the Development of Age-Related Hearing Impairment in Koreans? The Korean National Health and Nutrition Examination Survey 2009-2012

Objectives

The aim of this study was to evaluate whether body mass index (BMI) is associated with age-related hearing loss (ARHL) in the Asian elderly population.

Methods

Data from the Korean National Health and Nutrition Examination Survey 2009–2012 were used for the analyses. The pure tones at 0.5 and 1 kHz of both ears of each subject were averaged to obtain the low-frequency, those at 2 and 3 kHz were averaged to obtain the mid-frequency, and those at 4 and 6 kHz were averaged to obtain the high-frequency. The average hearing threshold (AHT) was calculated as pure tone average at 4 frequencies in the better ear. ARHL was defined as the AHT >25 dB.

Results

Univariate analyses revealed an increase in the BMI tertile in men was associated with a decreased low-frequency threshold, while an increase in the BMI tertile in women was associated with decreased mid- and high-frequency thresholds. Multivariate analyses adjusted for confounders show no significant differences in low-, mid-, or high-frequency. There was no significant difference in the prevalence of ARHL by BMI tertiles. Linear regression analyses show no association between BMI and low-, mid-, and high-frequency or AHTs. The area under the receiver operating characteristic curve values for AHT was 0.515 in men and 0.522 in women. The logistic regression analyses showed no association between BMI and ARHL in either sex.

Conclusion

BMI is not advantageous for the prediction of ARHL. In future epidemiological studies, BMI as a covariate of obesity may be replaced by other active metabolic parameters that have better predictive ability of ARHL than BMI.

Adiponectin at Physiologically Relevant Concentrations Enhances the Vasorelaxative Effect of Acetylcholine via Cav-1/AdipoR-1 Signaling

Clinical studies have identified hypoadiponectinemia as an independent hypertension risk factor. It is known that adiponectin (APN) can directly cause vasodilation, but the doses required exceed physiologic levels several fold. In the current study, we determine the effect of physiologically relevant APN concentrations upon vascular tone, and investigate the mechanism(s) responsible. Physiologic APN concentrations alone induced no significant vasorelaxation. Interestingly, pretreatment of wild type mouse aortae with physiologic APN levels significantly enhanced acetylcholine (ACh)-induced vasorelaxation (P<0.01), an endothelium-dependent and nitric oxide (NO)-mediated process. Knockout of adiponectin receptor 1 (AdipoR1) or caveolin-1 (Cav-1, a cell signaling facilitating molecule), but not adiponectin receptor 2 (AdipoR2) abolished APN-enhanced ACh-induced vasorelaxation. Immunoblot assay revealed APN promoted the AdipoR1/Cav1 signaling complex in human endothelial cells. Treatment of HUVECs with physiologic APN concentrations caused significant eNOS phosphorylation and nitric oxide (NO) production (P<0.01), an effect abolished in knockdown of either AdipoR1 or Cav-1. Taken together, these data demonstrate for the first time physiologic APN levels enhance the vasorelaxative response to ACh by inducing NO production through AdipoR1/Cav-1 mediated signaling. In physiologic conditions, APN plays an important function of maintaining vascular tone.

Therapeutic approaches of uncomplicated arterial hypertension in patients with COPD

The concomitant presence of systemic arterial hypertension and chronic obstructive pulmonary disease (COPD) is frequent. Indeed, arterial hypertension is the most common comorbid disease in COPD patients. Since many antihypertensive drugs can act on airway function the treatment of arterial hypertension in COPD patients appears complex. Moreover, in these patients, a combined therapy is required for the adequate control of blood pressure. Currently, available data are inconsistent and not always comparable. Therefore the aim of this review is to analyze how antihypertensive drugs can affect airway function in order to improve the clinical management of hypertensive patients with COPD. Thiazide diuretics and calcium channel blockers appear the first-choice pharmacological treatment for these patients.

Soybean β-Conglycinin Prevents Age-Related Hearing Impairment

Obesity-related complications are associated with the development of age-related hearing impairment. β-Conglycinin (β-CG), one of the main storage proteins in soy, offers multiple health benefits, including anti-obesity and anti-atherosclerotic effects. Here, to elucidate the potential therapeutic application of β-CG, we investigated the effect of β-CG on age-related hearing impairment. Male wild-type mice (age 6 months) were randomly divided into β-CG-fed and control groups. Six months later, the body weight was significantly lower in β-CG-fed mice than in the controls. Consumption of β-CG rescued the hearing impairment observed in control mice. Cochlear blood flow also increased in β-CG-fed mice, as did the expression of eNOS in the stria vascularis (SV), which protects vasculature. β-CG consumption also ameliorated oxidative status as assessed by 4-HNE staining. In the SV, lipofuscin granules of marginal cells and vacuolar degeneration of microvascular pericytes were decreased in β-CG-fed mice, as shown by transmission electron microscopy. β-CG consumption prevented loss of spiral ganglion cells and reduced the frequencies of lipofuscin granules, nuclear invaginations, and myelin vacuolation. Our observations indicate that β-CG ameliorates age-related hearing impairment by preserving cochlear blood flow and suppressing oxidative stress.

Contribution of adiponectin and its type 1 receptor to age-related hearing impairment

Age-related hearing impairment (ARHI) is a complex neurodegenerative disorder caused by a combination of environmental and genetic factors. We have reported previously that obesity increases the risk for ARHI, and that plasma levels of adiponectin are associated with ARHI. In the present study, we further explored the role of adiponectin in the pathophysiology of ARHI by investigating the genotypes of ADIPOQ and ADIPOR1, the genes of adiponectin and its type 1 receptor, respectively. A total of 1682 volunteers were enrolled, and their audiological phenotypes were determined according to the z scores converted from their original frequency-specific hearing thresholds. A total of 9 tag-single nucleotide polymorphisms (tagSNPs) in ADIPOQ and 4 tagSNPs in ADIPOR1 were genotyped, and the genotypes were correlated to the audiological phenotypes under the assumption of various inheritance models. Significant associations were identified between certain ADIPOQ tagSNPs and z scores under dominant, codominant, or additive models, whereas no association was identified between ADIPOR1 tagSNPs and z scores. The associations between ADIPOQ tagSNPs and z scores appear to exist only in subjects with specific ADIPOR1 genotypes, indicating an interaction between adiponectin and AdipoR1. Measurement of plasma adiponectin in 736 subjects revealed that ADIPOQ genotypes might exert their effects on hearing levels via modulation of plasma adiponectin levels. Subsequently, we confirmed the expression of AdipoR1 in the inner ear of mice, and demonstrated antiapoptotic effects of adiponectin in cochlear explant cultures. These results provide insights into the physiological function and potential clinical implications of adiponectin against ARHI.

No association between plasma adiponectin levels and central auditory function in adults

Adiponectin might play a protective role in cardiometabolic and peripheral auditory disorders, but its role on central auditory function was still unclear. The aim of this study was to examine whether there is an association between plasma adiponectin levels and central auditory function in adults. We recruited 297 adults, with normal or symmetrical sensorineural hearing loss and normal cognitive functions. Multivariate linear regression was performed to assess the association between plasma adiponectin concentrations and pitch pattern sequence (PPS) score, which was one of central auditory tests. The results showed that there were 224 (75.4%) women and 73 (24.6%) men in this study. The mean age was 58.1 ± 8.4 years, the mean waist circumference (WC) was 81.1 ± 8.3 cm, and the mean body mass index (BMI) was 24.0 ± 3.0 kg/m(2). The mean PPS score was 71.5 ± 14.1%, and plasma adiponectin concentration was 12.7 ± 5.5 g/mL. After adjusting for age, gender, WC, coronary artery disease, hypertension, diabetes mellitus, chronic kidney disease, smoking and drinking, plasma adiponectin concentrations (coefficient ± standard error, β ± SE = -0.09 ± 0.16, p = 0.563) were found to have no significant associations with PPS score. When WC was excluded from these variables in the multivariate linear regression model, plasma adiponectin concentrations (β ± SE = -0.03 ± 0.15, p = 0.855) were still not significantly associated with PPS score. In conclusion, plasma adiponectin levels were not significantly associated with PPS score, which was one of central auditory function tests. More studies should be conducted for the underlying mechanisms of obesity-related central auditory dysfunction.

Visceral Fat Area Determined Using Bioimpedance Analysis Is Associated with Hearing Loss

BACKGROUND

Visceral fat area (VFA) using bioimpedance analysis (BIA) as a simple analyzer can be used to assess VFA, which may be associated with HL. The aim of the present study was to evaluate the clinical relevance and usefulness of VFA using BIA as a predictor of HL.

PATIENTS AND METHODS

In total, 18,415 patients were recruited into our study. VFAs were measured using multi-frequency BIA. VFAs were normalized by body mass index (BMI). Participants were divided into 3 tertiles based on their VFA/BMI for both sexes. For both ears of each participant, the low-frequency (Low-Freq), mid-frequency (Mid-Freq), and high-frequency (High-Freq) values were obtained calculating the pure tone averages at 0.5 and 1 kHz, 2 and 3 kHz, and 4 and 6 kHz, respectively. The average hearing threshold (AHT) was calculated as the pure tone average at the 4 frequencies (i.e., 0.5, 1, 2, and 3 kHz). HL was defined as AHT >40 dB.

RESULTS

The VFA/BMI had the greatest AUROC among VFA, BMI, and VFA/BMI in both sexes in this study. In both univariate and multivariate analyses, VFA/BMI tertiles were associated with all 4 hearing thresholds (i.e., Low-Freq, Mid-Freq, High-Freq, and AHT). The 4 hearing thresholds were positively correlated with VFA/BMI as a continuous variable. The odds ratio for HL increased as the VFA/BMI tertile increased.

CONCLUSION

VFA/BMI was associated with hearing impairment in the Asian population. The participants with high VFA/BMI should be closely monitored for hearing impairment.