6102 Background: Neoadjuvant chemoimmunotherapy has shown high rates of pathological response in locally advanced head and neck squamous cell carcinoma (LA-HNSCC). However, its long-term survival outcomes, the predictive value of pathological complete response (pCR), and patterns of late failure remain unclear. Methods: In this single-arm phase II trial, 30 patients with resectable LA-HNSCC received three cycles of nab-paclitaxel (or docetaxel) plus cisplatin and camrelizumab, followed by surgery and adjuvant radiotherapy. The primary endpoint was pCR rate. With follow-up until January 2026, the median follow-up was 60 months. Analyses included overall survival (OS), recurrence patterns, and incidence of second primary tumors. Results: The pCR rate was 37.0% (10/27). Key Finding 1: This study represents the first report of 5-year long-term survival data for this regimen, with a 5-year OS rate of 76.7%. Key Finding 2: None of the patients who achieved pCR and completed adjuvant radiotherapy experienced local recurrence (0/7), whereas the recurrence rate was 33.3% (1/3) among those who did not receive radiotherapy, underscoring the role of radiotherapy even in pCR patients. Key Finding 3: Six patients (20%) developed second or third primary tumors during long-term follow-up (sites included larynx, esophagus, and lung), with incidence increasing over time. Key Finding 4: Two patients developed osteoradionecrosis of the jaw more than two years after radiotherapy, leading to malnutrition and subsequent death, highlighting the importance of long-term toxicity management. Conclusions: Neoadjuvant chemoimmunotherapy provides durable survival benefit in LA-HNSCC. pCR is associated with minimal local recurrence. However, with prolonged survival, the risk of second primary tumors becomes significant, and late radiation toxicities can impact outcomes. These findings emphasize the need for establishing lifelong surveillance protocols for multiple primary cancers and systematic management of late toxicities in this population. Clinical trial information: ChiCTR1900025303.

PURPOSE:We assessed the feasibility and efficacy of a response-adapted surgical strategy in patients with locally advanced head and neck squamous cell carcinoma (LA-HNSCC) achieving major tumor regression after neoadjuvant immunochemotherapy (NAICT). PATIENTS AND METHODS:This phase II, single-arm, prospective trial enrolled patients with resectable, human papillomavirus-negative stage III to IVA LA-HNSCC. All received three cycles of NAICT (penpulimab, nab-paclitaxel, and cisplatin). Pre-cycle 3 imaging and laryngoscopy guided surgery: Patients with ≥50% primary tumor regression underwent reduced-volume surgery (RVS); those with <50% regression received standard-volume surgery (SVS). All received risk-adapted adjuvant radiotherapy. The primary endpoint was 2-year disease-free survival (DFS). RESULTS:Fifty patients completed NAICT, with an objective response rate of 94% [95% confidence interval (CI), 84%-99%]. At a median follow-up of 34.0 months (IQR, 30.1-39.5), the 2-year DFS for the per-protocol cohort was 83% (95% CI, 69%-91%). The RVS group (n = 42) achieved a 2-year DFS of 90% (95% CI, 77%-96%) with 100% laryngeal preservation in laryngeal/hypopharyngeal cancers, whereas the SVS group (n = 5) had a 2-year DFS of 20% (95% CI, 0.8%-58%). Grade 3 adverse events (AE) occurred in 16% of patients related to NAICT and in 15% related to surgery; there were no grade 4 or 5 AEs. At 9 months after radiotherapy, most quality-of-life scores improved or stabilized compared with baseline. CONCLUSIONS:The REMATCH trial provides the first prospective evidence that a response-adapted surgical strategy after NAICT is feasible. Patients achieving ≥50% primary tumor regression derived promising survival and universal laryngeal preservation. These findings support the initiation of phase III randomized trials to validate this de-escalation strategy.

Well-differentiated liposarcoma (WDLPS), also termed atypical lipomatous tumor, is a low-grade malignant adipocytic neoplasm characterized by indolent growth, limited metastatic potential, and a propensity for local recurrence. Primary WDLPS arising in the hypopharyngeal region is exceptionally rare, particularly in young adults, and may clinically mimic benign submucosal lesions. We report the case of a 24-year-old man who presented with a one-month history of persistent foreign body sensation in the throat. Flexible laryngoscopy revealed a smooth submucosal mass arising from the left hypopharyngeal region, and contrast-enhanced magnetic resonance imaging demonstrated a well-circumscribed enhancing lesion without cervical lymphadenopathy. The mass was excised transorally under general anesthesia. Histopathological examination showed mature adipocytic proliferation with atypical stromal cells, and immunohistochemistry demonstrated positivity for MDM2, CDK4, CD34, and p16. Fluorescence in situ hybridization confirmed MDM2 gene amplification, establishing the diagnosis of WDLPS. Although the early postoperative course was uneventful and initial follow-up showed satisfactory mucosal healing, serial laryngoscopic examinations at 2, 2.5, and 4 months after surgery revealed early local recurrence at the surgical site. This case highlights that hypopharyngeal WDLPS can occur in young adults and may recur early even after apparently complete transoral excision. Accurate diagnosis requires integration of histopathology, MDM2/CDK4 immunohistochemistry, and molecular confirmation of MDM2 amplification. Close endoscopic and radiological surveillance is essential for early detection of local recurrence.

6011 Background: The standard of care for resectable HNSCC includes extensive surgical margins to ensure complete oncologic resection, often at the expense of significant functional impairment. Recent advancements in neoadjuvant PD-1 inhibitors with chemotherapy, have shown potential in achieving substantial tumor regressions. This study posits that such neoadjuvant immunochemotherapy can allow for narrower surgical margins without compromising oncological outcomes, potentially preserving vital anatomical structures and function. Methods: This single-center, phase II clinical study (NCT05459415) enrolled 52 patients with operable, HPV-negative locally advanced HNSCC. Participants received three cycles of the AP chemotherapy regimen combined with 200 mg of the PD-1 inhibitor Penpulimab. Tumor response was assessed via MRI and laryngoscopy after the second cycle. Patients achieving greater than 50% reduction in tumor size were selected for conservative-margin surgical resection. Surgical Protocol: If imaging or endoscopy identifies residual tumor, margins will be expanded 5-10mm beyond the tumor edges to ensure clear margins, confirmed by intraoperative frozen section analysis by dual pathologists, ensuring maximal oncologic safety and functional preservation. For patients achieving CR, surgical planning relies on prior diagnostic imaging and endoscopic outcomes to guide precise resections of the larynx and hypopharynx. Post-surgical adjuvant treatment was based on final pathology results, including further immunotherapy for nine cycles. Results: Of the initial cohort, 50 patients were evaluable for response; the objective response rate (ORR) stood at 96%, and a pathologic complete response (pCR) was observed in 40.7% of patients. Forty-seven patients proceeded to surgery, all maintaining laryngeal function, and 91.5% underwent reduced-margin resection based on deep imaging response, with a pCR achieved in 44.2% of these cases. The study noted clinical adverse events, including three unrelated deaths and two instances of severe postoperative complications. The 12-month and 24-month Event-Free Survival (EFS) rates were calculated at 97.62% and 89.28% respectively. The overall survival (OS) rate at 24 months was 92.85%. Conclusions: The REMATCH2201 trial supports the feasibility of reduced-margin surgery in patients with HPV-negative advanced HNSCC following effective neoadjuvant immunochemotherapy, without increasing the risk of oncologic recurrence. This approach importantly spares critical functional anatomy, advocating for a paradigm shift in the surgical management of these tumors. Nevertheless, further research in a multi-center, randomized controlled trial setting is required to substantiate these findings and refine protocols for broader application in clinical practice. Clinical trial information: NCT05459415 .

e18046 Background: In the traditional chemotherapy paradigm, Surgical resection was tailored to the tumor's pre-treatment dimensions. Neoadjuvant immunochemotherapy has demonstrated higher remission rates and more profound tumor regression, suggest a substantial reduction in necessary surgical margins. Hence, reducing the surgical resection extent following neoadjuvant immunochemotherapy could maintain treatment efficacy while conserving critical organ functionality. Methods: This single-center, single-arm Phase II clinical trial (NCT05459415) included patients with locally advanced HPV- HNSCC. Participants underwent three cycles of AP chemotherapy (Albumin-bound paclitaxel 260mg/m^2+DDP 75mg/m^2) with 200mg Penpulimab. Laryngoscope and MRI examinations occurred after the second cycle. Surgery: Patients exhibiting a tumor reduction greater than 50% will be evaluated by MDT, Decisions regarding surgery will be performed by expanding 5-10mm beyond the post-treatment tumor margins. If both examinations suggest CR, a functional-sparing subzones resection was performed based on a negative intraoperative rapid frozen section at the site of the original tumor bed. Cervical lymph nodes underwent standard dissection. Subsequent adjuvant radiotherapy or chemoradiotherapy was tailored to the pathological findings, with a continuation of immunotherapy for an additional nine cycles. The study's primary focus was on 2-year EFS survival, this report were preliminary analyses. Results: From July 1, 2022, to July 20, 2023, 52 patients (51 males, 1 female; median age 61, range 39-70) were recruited, with a median follow-up of 349 days. Tumor distribution was as follows: laryngeal (21), hypopharyngeal (25), tonsillar (4), and oral (2) carcinoma cases. Among the 50 patients subjected to imaging, the objective response rate (ORR) reached 96%. Out of 47 patients undergoing surgery, laryngeal organ preservation was achieved in 100%, with a 40.7% pathologic complete response (pCR) rate, and surgery margin reduced by 91.5% (deep remission), 10.6% R1 resection rate (5 patients with image-based reduction but positive margins),one multi-point biopsy(pCR, patient refused resection surgery).Grade 3 or higher adverse events included 2 neoadjuvant therapy-related deaths (inflammatory storm and pulmonary infection), 1 postoperative COVID-19-related sudden death, along with cases of interstitial pneumonia(1), immune encephalitis(1), immune enteritis(1), surgical site infection(1), neutropenia(3), and hyponatremia(1). Conclusions: Patients achieving profound tumor regression with neoadjuvant immunochemotherapy may present the possibility of safe surgical resection with reduced margins, enhancing organ preservation and minimizing surgical trauma. Clinical trial information: NCT05459415 .

OBJECTIVES:Neoadjuvant chemoimmunotherapy has shown promising results for resectable, locoregionally advanced (LA) head and neck squamous cell carcinoma (L/A HNSCC). We published the first phase II trial of neoadjuvant camrelizumab combined with chemotherapy in resectable, L/A HNSCC, demonstrating it was safe and feasible with favorable pathological complete response (pCR). Here, we report the final analysis results for neoadjuvant chemoimmunotherapy in L/A HNSCC (minimum 2.0 years of follow-up). MATERIALS AND METHODS:Three cycles of chemoimmunotherapy were administered before surgery to patients with L/A HNSCC. Two-year disease-free survival (DFS), overall survival (OS) and quality of life (QOL) were reported. RESULTS:The overall two-year DFS and OS rates were 90 % and 100 %, respectively. With a median follow-up of 33.7 months, 9 of 10 (90 %) patients with pCR were alive and disease free. Patients with TNM stage (II/III) or < 20 % of residual viable tumor trended toward improved DFS; hazard ratio (HR), 0.44 [95 % confidence interval (CI), 0.04-5.28] and HR, 0.26 (95 % CI, 0.03-2.36), respectively. All QLQ-C30 functioning and symptom scales other than nausea and vomiting were resolved at 2 years after the completion of radiotherapy. CONCLUSION:Neoadjuvant camrelizumab in combination with chemotherapy provided encouraging clinical outcomes for patients with L/A HNSCC. Further studies with longer follow-up and larger samples are warranted. TRIAL REGISTRATION:Chictr.org.cn, ChiCTR1900025303. Registered Aug 22, 2019. https://www.chictr.org.cn/showproj.html?proj=41380.

ObjectiveThere was disagreement over the association between serum/plasma homocysteine (HCY) levels and sudden sensorineural hearing loss (SSNHL). Through the use of a meta-analysis, this study aims to determine whether there is a significant difference in serum homocysteine levels between the SSNHL group and the control group.DesignThe Cochrane Library, EMBASE, and PubMed databases were all thoroughly searched. The two independent reviewers thoroughly examined the initially searched articles. The data results were calculated by standard mean difference (SMD) or odds ratios (OR). Review Manager (version 5.3) was applied to statistical data.Study sampleThere were 766 participants in the 6 trials with continuous outcomes that were part of the meta-analysis A. In addition, meta-analysis B, which included 961 people, contained a total of 3 studies with dichotomous results.ResultsBoth meta-analyses revealed the same conclusion that serum/plasma HCY levels in the SSNHL patients are higher than those in the controls (SMD 0.41, 95 % confidence interval (CI) 0.11 to 0.72, P < 0.01; OR 3.27, 95 % CI 2.16 to 4.94, P < 0.01).ConclusionThis study demonstrated that the SSNHL patients' serum/plasma HCY levels were greater than those of the control group.

Supplementary Data from Neoadjuvant Chemoimmunotherapy for the Treatment of Locally Advanced Head and Neck Squamous Cell Carcinoma: A Single-Arm Phase 2 Clinical Trial

Abstract Purpose: This study aimed to assess the antitumor activity and safety of neoadjuvant chemotherapy combined with PD-1 inhibitor camrelizumab in patients with locally advanced head and neck squamous cell carcinoma (HNSCC). Patients and Methods: In this single-center, single-arm, phase 2 trial, patients with resectable stage III–IVB HNSCC received chemotherapy [albumin-bound paclitaxel 260 mg/m2 (or docetaxel 75 mg/m2) plus cisplatin 75 mg/m2] and camrelizumab 200 mg on day 1 of each 21-day cycle for three cycles, followed by surgery, and adjuvant radiotherapy. Co-primary end points were pathological complete response (pCR) rate and safety. Results: Thirty patients were enrolled and completed the neoadjuvant therapy, with an objective response rate (ORR) of 96.7% (29/30). Twenty-seven patients underwent surgery without delay, with an R0 resection rate of 92.6% (25/27). The clinical to pathological downstaging rate was 100% (27/27). The pCR rate was 37.0% [95% confidence interval (CI), 19.4%–57.6%], and the major pathological response (MPR) rate was 74.1% (95% CI, 53.7%–88.9%). The median follow-up duration was 16.1 months (range, 8.3–28.5), and the disease-free survival rate at 12 months was 95.8% (95% CI, 73.9%–99.4%). Grade 3 neoadjuvant therapy–related adverse events included rash (1; 3.3%), pruritis (1; 3.3%), and thrombocytopenia (1; 3.3%), and no grade 4 or 5 treatment-related events occurred. The most common surgical complication was delayed wound healing (5; 18.5%). Conclusions: Neoadjuvant chemotherapy plus camrelizumab for locally advanced HNSCC showed high ORR, pCR, and MPR rates, with an acceptable safety profile. These data support further evaluation of neoadjuvant chemoimmunotherapy for the treatment of locally advanced HNSCC.

Background: Studies have shown that Helicobacter pylori (H. pylori) infection may be associated with the occurrence of otitis media with effusion (OME) in children. Objective: This is a systematic review of the relevant published literature to explore the relationship between H. pylori infection and OME in children. Method: Articles published before October 30, 2019 in the PubMed, Web of Science, Ovid, the China National Knowledge Infrastructure (CNKI) database, and Wanfang databases were retrieved. Articles were screened based on prespecified inclusion and exclusion criteria. Quality assessment was applied to the included studies. Data in the included studies were extracted and classified for qualitative analysis. Results: Ten studies, which enrolled a total of 397 cases and 334 controls, were included; all were case-control studies of varying quality. We summarized and compared H. pylori infections in different specimens from pediatric patients with OME. Due to the apparent heterogeneity between the included studies, meta-analysis was not appropriate, hence we carried out only a qualitative analysis. Conclusion: The detection rate of H. pylori in the middle ear, tonsil and gastric juice in children with OME was higher than that in children without OME. There is no clear and reliable conclusion as to whether there is a difference in the detection rate of H. pylori in adenoid specimens of children with or without OME. Eradication of H. pylori may improve symptoms of drug-resistant OME. Nevertheless, more studies of higher quality are needed to improve the conclusions.

Guanylate binding proteins ( GBPs ) belongs to the interferons (IFNs) induced guanylate-binding protein family (Guanosine triphosphatases, GTPases) consisting of seven homologous members, termed GBP1 to GBP7 . We used multidimensional survey ways to explore GBPs expression, regulation, mutations, immune infiltration and functional networks in head and neck squamous cell carcinoma (HNSCC) patient data based on various open databases. The study provides staggered evidence for the significance of GBPs in HNSCC and its potential role as a novel biomarker. Our results showed that over expressions of 7 GBPs members and multivariate analysis suggested that N-stage, high expressions of GBP1 and low expression of GBP6/7 were linked to shorter OS in HNSCC patients. In addition, B cells of immune infiltrates stimulant the prognosis and might have a medical prognostic significance linked to GBPs in HNSCC. We assume that GBPs play a synergistic role in the viral related HNSCC. Our results show that data mining efficiently reveals information about GBPs expression in HNSCC and more importance lays a foundation for further research on the role of GBPs in cancers.

This study aimed to develop a novel surgery classification for an endoscopic approach to middle ear cholesteatoma. We retrospectively analyzed the surgical approaches and outcomes of patients with middle ear cholesteatoma. Middle ear cholesteatoma surgeries were divided into four types and two special types as follows: type I, attic retraction pocket, which only requires tympanostomy tube placement or retraction pocket resection and cartilage reconstruction; type II, cholesteatoma which is limited to the attic or in which endoscopy can confirm complete removal of mastoid cholesteatoma lesions, including type II a, requiring only use of a curette, and type II b, requiring use of an electric drill or chisel; type III, cholesteatoma not limited to the attic, in which endoscopy cannot confirm complete removal of mastoid cholesteatoma lesions, requiring the combined use of endoscope and microscope to perform endoscopic tympanoplasty and "Canal Wall Up" mastoidectomy; type IV, extensive involvement of mastoid cavity cholesteatoma lesions and/or cases with a potential risk of complications, removal of which can only be performed under a microscope for "Canal Wall Down" mastoidectomy. In addition, there were two special types: "difficult external auditory canal" and congenital cholesteatoma in children. In our system, type I and type II middle ear cholesteatoma surgery was completely performed under an endoscope alone. However, estimating the extent of the lesions, determining the choice of mastoid opening and reestablishing ventilation are the key points for an endoscopic approach to middle ear cholesteatoma. The classification of endoscopic middle ear cholesteatoma surgery may benefit the selection of surgical indications.

BackgroundO6-methylguanine-DNA methyl-transferase (MGMT) gene, a DNA repair gene, plays a critical role in the repair of alkylated DNA adducts that form following exposure to genotoxic agents. MGMT is generally expressed in various tumors, and its function is frequently lost because of hypermethylation in the promoter. The promoter methylation of MGMT has been extensively investigated in head and neck squamous cell carcinoma (HNSCC). However, the association between the promoter methylation of MGMT and HNSCC risk remains inconclusive and inconsistent. Therefore, we performed a meta-analysis to better clarify the association between the promoter methylation of MGMT and HNSCC risk.MethodsA systematical search was conducted in PubMed, Web of Science, EMBASE, and Ovid for studies on the association between MGMT promoter methylation and HNSCC. Odds ratio (ORs) and 95% confidence intervals (CI) were calculated to estimate association between MGMT promoter methylation and risk of HNSCC. The meta-regression and subgroup analysis were undertaken to explore the potential sources of heterogeneity.ResultsTwenty studies with 1,030 cases and 775 controls were finally included in this study. The frequency of MGMT promoter methylation was 46.70% in HNSCC group and 23.23% in the control group. The frequency of MGMT promoter methylation in HNSCC group was significantly higher than the control group (OR = 2.83, 95% CI = 2.25-3.56).ConclusionThis meta-analysis indicates that aberrant methylation of MGMT promoter was significantly associated with the risk of HNSCC, and it may be a potential molecular marker for monitoring the disease and may provide new insights to the treatment of HNSCC.

BackgroundOvarian cancer is the primary cause of death in women diagnosed with gynecological malignancies worldwide. Absence of early symptoms prevents prompt diagnosis or successful therapeutic intervention. P16(INK4a) is a well-known tumor suppressor gene (TSG). Aberrant methylation of TSG promoter is an important epigenetic silencing mechanism leading to ovarian cancer progression. Studies have reported differences in methylation frequencies of the p16(INK4a) promoter between ovarian cancer and the corresponding control group. However, the association between p16(INK4a) promoter methylation and ovarian cancer remains unclear and controversial. Therefore, a meta-analysis was conducted to clarify the relationship between p16(INK4a) promoter methylation and ovarian cancer.MethodsPubMed, Web of Science, EMBASE and CNKI were searched to identify eligible studies for the evaluation of the association between p16(INK4a) promoter methylation and ovarian cancer. Odds ratio (ORs) and 95% confidence intervals (95% CI) were calculated to determine the strength of association between p16(INK4a) promoter methylation and ovarian cancer.ResultsA total of 612 ovarian cancer patients and 289 controls from 12 eligible studies were included in the meta-analysis. Overall, a significant association was observed between p16(INK4a) methylation status and ovarian cancer risk using a fixed-effects model (OR = 2.02, 95% CI = 1.39-2.94).ConclusionThe results of our meta-analysis show that aberrant methylation of p16(INK4a) promoter was significantly associated with ovarian cancer. It may represent a promising molecular marker to monitor the disease and provides new insights into the treatment of human ovarian cancer.

Age‐associated degeneration in the central auditory system, which is defined as central presbycusis, can impair sound localization and speech perception. Research has shown that oxidative stress plays a central role in the pathological process of central presbycusis. Thioredoxin 2 (Trx2), one member of thioredoxin family, plays a key role in regulating the homeostasis of cellular reactive oxygen species and anti‐apoptosis. The purpose of this study was to explore the association between Trx2 and the phenotype of central presbycusis using a mimetic aging animal model induced by long‐term exposure to d‐galactose (d‐Gal). We also explored changes in thioredoxin‐interacting protein (TXNIP), apoptosis signal regulating kinase 1 (ASK1) and phosphorylated ASK1 (p‐ASK1) expression, as well as the Trx2–TXNIP/Trx2–ASK1 binding complex in the auditory cortex of mimetic aging rats. Our results demonstrate that, compared with control groups, the levels of Trx2 and Trx2–ASK1 binding complex were significantly reduced, whereas TXNIP, ASK1 p‐ASK1 expression, and Trx2–TXNIP binding complex were significantly increased in the auditory cortex of the mimetic aging groups. Our results indicated that changes in Trx2 and the TXNIP–Trx2–ASK1 signal pathway may participate in the pathogenesis of central presbycusis.

Presbycusis is the most common functional disabling disease, the pathogenesis of which has not been clarified up to now and there is lack of effective treatment method for this reason. It has been recently reported that it is a com-prehensive disease resulted from the interaction between the hereditary factors and environmental factors. The 4977bp deletion of presbycusis in human (The 4834bp deletion of mitochondrial DNA in rat) were called the Common Dele-tion, which were considered relating to the Presbycusis. The aim of this paper is to review the studying of the presbycusis associated with mitochondrial DNA deletion, present the progress in pathogenesis and therapy research( using the es-tablished in vivo and in vitro model) of this presbycusis .

Aging is a natural process usually defined as a progressive loss of function with an accumulation of senescent cells. The clinical manifestations of this process include age-related hearing loss (AHL)/presbycusis. Several investigations indicated the association between a mitochondrial common deletion (CD) (mtDNA 4977-bp deletion in humans, corresponding to 4834-bp deletion in rats) and presbycusis. Previous researches have shown that peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) is a key regulator of mitochondrial biogenesis and energy metabolism. However, the expression of PGC-1α in the inner ear and the possible effect of PGC-1α on presbycusis are not clear. Our data demonstrated the distribution of PGC-1α and its downstream transcription factors nuclear respiratory factor-1 (NRF-1), mitochondrial transcription factor A (Tfam) and nuclear factor κB (NF-κB) in marginal cells (MCs) for the first time. To explore the role of PGC-1α in cellular senescence, we established a model of marginal cell senescence harboring the mtDNA4834 common deletion induced by d-galactose. We also found that PGC-1α and its downstream transcription factors compensatorily increased in our cell senescence model. Furthermore, the overexpression of PGC-1α induced by transfection largely increased the expression levels of NRF-1 and TFAM and significantly decreased the expression level of NF-κB in the cell senescence model. And the levels of CD, senescent cells and apoptotic cells in the cell model decreased after PGC-1α overexpression. These results suggested that PGC-1α might protect MCs in this cell model from senescence through a nuclear-mitochondrial interaction and against apoptosis. Our study may shed light on the pathogenesis of presbycusis and provide a new therapeutic target for presbycusis.

In humans, chronic dyslipidemia associated with elevated triglycerides may reduce auditory function. However, there is little evidence available in the literature concerning the effects of a long-term high-fat diet (HFD) on the inner ears of animals. The purpose of this study was to investigate the effect of 12 month-HFD on the inner ear of Sprague–Dawley rats and on the d-galactose (d-gal)-induced aging process in the inner ear. We found that 12 month-HFD markedly elevated the auditory brainstem response (ABR) threshold in the high-frequency region. The HFD significantly increased the generation of reactive oxygen species (ROS) and the expressions of NADPH oxidase (NOX) and the uncoupling proteins (UCP). Furthermore, an elevated accumulation of the mitochondrial DNA (mtDNA) common deletion (CD) and mitochondrial ultrastructural changes in the inner ear suggested that there was mitochondrial damage in response to the excessive fat intake. The expression level of cleaved caspase-3 and the number of terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end-labelling (TUNEL)-positive cells in the inner ear were increased by the HFD. The effects of d-gal on the inner ears were similar with 12 month-HFD. We found that rats receiving both the HFD and d-gal exhibited a greater shift in the ABR threshold, larger increases in the expression levels of NOX, UCP and cleaved caspase-3 and an increased number of TUNEL-positive cells in the inner ear. The present study demonstrated that HFD may induce oxidative stress, mitochondrial damage and apoptosis in the inner ear, and it provided evidence regarding the link between HFD and an increased risk of age-related hearing loss.

The age-related deterioration in the central auditory system is well known to impair the abilities of sound localization and speech perception. However, the mechanisms involved in the age-related central auditory deficiency remain unclear. Previous studies have demonstrated that mitochondrial DNA (mtDNA) deletions accumulated with age in the auditory system. Also, a cytochrome c oxidase (CcO) deficiency has been proposed to be a causal factor in the age-related decline in mitochondrial respiratory activity. This study was designed to explore the changes of CcO activity and to investigate the possible relationship between the mtDNA common deletion (CD) and CcO activity as well as the mRNA expression of CcO subunits in the auditory cortex of d-galactose (d-gal)-induced mimetic aging rats at different ages. Moreover, we explored whether peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM) were involved in the changes of nuclear- and mitochondrial-encoded CcO subunits in the auditory cortex during aging. Our data demonstrated that d-gal-induced mimetic aging rats exhibited an accelerated accumulation of the CD and a gradual decline in the CcO activity in the auditory cortex during the aging process. The reduction in the CcO activity was correlated with the level of CD load in the auditory cortex. The mRNA expression of CcO subunit III was reduced significantly with age in the d-gal-induced mimetic aging rats. In contrast, the decline in the mRNA expression of subunits I and IV was relatively minor. Additionally, significant increases in the mRNA and protein levels of PGC-1α, NRF-1 and TFAM were observed in the auditory cortex of d-gal-induced mimetic aging rats with aging. These findings suggested that the accelerated accumulation of the CD in the auditory cortex may induce a substantial decline in CcO subunit III and lead to a significant decline in the CcO activity progressively with age despite compensatory increases of PGC-1α, NRF-1 and TFAM. Therefore, CcO may be a specific intramitochondrial site of age-related deterioration in the auditory cortex, and CcO subunit III might be a target in the development of presbycusis.

Mitochondrial DNA (mtDNA) mutations, especially deletions, have been suggested to play an important role in aging and degenerative diseases. In particular, the common deletion in humans and rats (4977 bp and 4834 bp deletion, respectively) has been shown to accumulate with age in post-mitotic tissues with high energetic demands. Among numerous deletions, the common deletion has been proposed to serve as a molecular marker for aging and play a critical role in presbyacusis. However, so far no previous publication has quantified the contribution of common deletion to the total burden of mtDNA deletions in tissues during aging process. In the present study, we established a rat model with various degrees of aging in inner ear induced by three different doses of d-galactose (d-gal) administration. Firstly, multiple mtDNA deletions in inner ear were detected by nested PCR and long range PCR. In addition to the common deletion, three novel mtDNA deletions were identified. All four deletions, located in the major arc of mtDNA, are flanked by direct repeats and involve the cytochrome c oxidase (COX) subunit III gene, encoded by mtDNA. Additionally, absolute quantitative real-time PCR assay was used to detect the level of common deletion and total deletion burden of mtDNA. The quantitative data show that the common deletion is the most frequent type of mtDNA deletions, exceeding 67.86% of the total deletion burden. Finally, increased mtDNA copy number, reduced COX activity and mosaic ultrastructural impairments in inner ear were identified in d-gal-induced aging rats. The increase of mtDNA replication may contribute to the accelerated accumulation of mtDNA deletions, which may result in impairment of mitochondrial function in inner ear. Taken together, these findings suggest that the common deletion may serve as an ideal molecular marker to assess the mtDNA damage in inner ear during aging.