[Advances in glucocorticoid resistance in otorhinolaryngological diseases].

Glucocorticoids（GC） are widely used in the clinical treatment of autoimmune inner ear diseases, sudden sensorineural hearing loss, Meniere's disease, sinusitis and other otolaryngology diseases. However, GC resistance remains a major factor contributing to the poor efficacy of clinical treatments. The mechanism of GC resistance is still unclear. This paper reviews the related mechanisms of GC resistance from the perspectives of GC receptor factors and non-GC receptor factors. Additionally, it summarizes the latest research progress on GC resistance in otolaryngological diseases, with the aim of identifying effective clinical alternative treatment options for reversing GC resistance in the future.

[Hearing care network for early identification of delayed hearing loss in preschool children].

Objective:To establish a hearing care network for preschool children in Nanjing, to perform early identification and intervention for delayed hearing loss, and to evaluate the application effect of the hearing care network. Methods:Through the establishment of a hearing care network, hearing screening, diagnosis and follow-up of preschool children were conducted. Distortion product otoacoustic emissions（DPOAE） was adopted for primary hearing screening. Children who failed in the primary screening were re-screened within half a month. DPOAE and acoustic impedance test were used for hearing re-screening. Clinical diagnosis and audiological evaluation were performed for children who failed in the re-screening. Speech assessment, hearing aid intervention, and audio-speech follow-up were conducted for children diagnosed with delayed hearing loss. Results:Among 29 919 preschool children completing the hearing screening from May 2019 to September 2022, 3208 cases（10.7%） failed the primary screening and 1437 cases（47.7%） failed the re-screening. Total 747 children completed the hearing diagnosis, and 70 children were diagnosed with delayed hearing loss, with a detection rate of 0.23%. Among them, 20 cases were accompanied by language development delay, in which 12 cases received hearing aids and 2 cases received cochlear implantation. In addition, speech assessment and audiological follow-up were completed for 53 children. Conclusion:The hearing screening for preschool children is beneficial for early detection of children with delayed hearing loss and language development delay. Besides, the establishment of hearing care network is conducive to early identification and intervention of children with hearing loss.

Inflammatory Indicators in Peripheral Blood in Sudden Sensorineural Hearing Loss Patients With Different Audiogram Shapes.

Objective: A retrospective study was conducted to explore the immune-inflammatory responses in sudden sensorineural hearing Loss (SSNHL) patients with different audiogram shapes. Methods: One hundred and ten inpatients with SSNHL were assigned to 4 subgroups according to the audiogram shape and treated with systemic methylprednisolone. The numbers of white blood cells, neutrophils, lymphocytes, platelets, and monocytes were counted. The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and the monocyte-to-lymphocyte ratio (MLR) were calculated and statistically analyzed. Results: Neutrophil-to-lymphocyte ratio, MLR, and systemic immune index (SII) of SSNHL patients were significantly higher than the control group, while PLR was not statistically significant. There were no statistical differences in NLR, PLR, MLR, and SII among the 4 subgroups. Conclusion: Immune-inflammatory response may be a common pathogenesis in all SSNHL patients with different audiogram shapes. The predictive value of these hematologic markers needs further research in the future.

Overexpression of LIMA1 Indicates Poor Prognosis and Promotes Epithelial-Mesenchymal Transition in Head and Neck Squamous Cell Carcinoma.

Background: LIMA1 encodes LIM domain and actin binding 1, a cytoskeleton-associated protein whose loss has been linked to migration and invasion behavior of cancer cells. However, the roles of LIMA1 underlying the malignant behavior of tumors in head and neck squamous cell carcinoma (HNSC) are not fully understood. Methods: We conducted a multi-omics study on the role of LIMA1 in HNSC based on The Cancer Genome Atlas data. Subsequent in vitro experiments were performed to validate the results of bioinformatic analysis. We first identified the correlation between LIMA1 and tumor cell functional states according to single-cell sequencing data in HNSC. The potential downstream effects of LIMA1 were explored for gene ontology and Kyoto Encyclopedia of Genes and Genomes pathways through functional enrichment analysis of the gene sets that correlated with LIMA1 in HNSC. The prognostic role of LIMA1 was assessed using the log rank test to compare difference in survival between LIMA1High and LIMA1Low patients. Univariate Cox regression and multivariate Cox regression were further carried out to identify the prognostic value of LIMA1 in HNSC. Results: LIMA1 was identified as a prognostic biomarker and is associated with epithelial-mesenchymal transition (EMT) progress in HNSC. In vitro silencing of LIMA1 suppressed EMT and related pathways in HNSC. Conclusions: LIMA1 promotes EMT and further leads to tumor invasion and metastasis. Increased expression of LIMA1 indicates poor survival, identifying it as a prognostic biomarker in HNSC.

Identification of the Fungal Community in Otomycosis by Internal Transcribed Spacer Sequencing.

We used internal transcribed spacer (ITS) sequencing to identify the fungal community in otomycosis patients and to evaluate the treatment effects of bifonazole. Ten patients who visited the Department of Otolaryngology of Jiangsu Provincial Hospital on Integration of Chinese and Western Medicine from May 2020 to April 2021 were recruited. Otomycosis patients were treated with bifonazole solution once a day for 14 days. Samples collected from the external auditory canal before and after treatment (Pre-treatment, n = 14 ears; Post-treatment, n = 14 ears) were used for microscopic examination, fungal culture, and ITS sequencing. Samples collected from 10 volunteers (Control, n = 20 ears) were used as controls. The symptoms, including ear itching, aural fullness, otalgia, hearing loss, and physical signs were recorded before treatment as well as on the 7th and 14th days after treatment. Aspergillus was identified as a main pathogenic fungus by microscopic examination, fungal culture, and ITS sequencing. At the genus level, Aspergillus was more abundant in the pre-treatment group than the control and post-treatment groups, and Malassezia was more abundant in the control and post-treatment groups than the pre-treatment group. The fungal species richness and diversity reduced significantly in the pre-treatment group compared with the control and post-treatment groups. The effective rate of bifonazole was 64.29% and 100% on the 7th and 14th days after treatment, respectively. In conclusion, the results obtained from morphologic studies and ITS sequencing indicate that Aspergillus is the main pathogenic fungus of otomycosis patients in Nanjing, Jiangsu Province, China. Malassezia is the dominant resident fungi in healthy individuals. ITS sequencing provides comprehensive information about fungal community in otomycosis and is helpful in evaluating the efficacy of antifungal agents.

Inhibition of macrophage migration inhibitory factor alleviates LPS-induced inflammation response of HEI-OC1 cells via suppressing NF-κB signaling.

BACKGROUND: Sudden sensorineural hearing loss (SSNHL) is acute and unexplained. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine in several inflammatory diseases. However, its role in SSNHL remains elusive. METHODS: Lipopolysaccharide (LPS) was used to induce the inflammatory response of murine auditory cells, HEI-OC1. Silencing of MIF in HEI-OC1 cells was achieved by transfection of short hairpin RNA against MIF. 740Y-P and IMD0354 were used to stimulate the PI3K pathway and suppress the NF-κB pathway, respectively. RT-qPCR and western blotting were used to examine MIF and cyclooxygenase 2 (COX2) expression in LPS-treated HEI-OC1 cells. ELISA was employed to assess prostaglandin E2 (PGE2) concentrations. RESULTS: MIF was upregulated in LPS-treated HEI-OC1 cells. MIF knockdown reduced PGE2 synthesis and COX2 expression in LPS-treated HEI-OC1 cells. Moreover, MIF knockdown suppressed activation of the PI3K/AKT and NF-κB pathway in LPS-treated HEI-OC1 cells. Additionally, inhibition of MIF decreased PGE2 production and COX2 expression via inactivation of the NF-κB pathway. CONCLUSION: Inhibition of MIF alleviated LPS-induced inflammation in HEI-OC1 cells via inactivating the NF-κB signaling, which might provide a better understanding for SSNHL development.

Comparison between postauricular steroid injection and intratympanic steroid perfusion for refractory severe and profound sudden sensorineural hearing loss.

BACKGROUND: To analyze the clinical efficacy of intratympanic steroid perfusion (ISP) and postauricular steroid injection (PSI) for refractory severe and profound sudden sensorineural hearing loss (SSNHL). METHODS: SSNHL patients who failed a conventional treatment with severe to profound hearing loss [pure tone average (PTA, 0.25-8 kHz) > 60 dB] were treated with ISP or PSI plus antioxidant and neurotrophin for 10 consecutive days. Antioxidant and neurotrophin were administrated either intravenously and/or orally. All patients were assigned into the ISP group or the PSI group and followed up for more than three months. The changes in PTA, effective rate and side effects were analyzed in the two groups. RESULTS: Similar hearing improvements and effective rates were observed in the two groups. However, a slightly better efficacy was observed in the PSI group compared to the ISP group. Patients with shorter intervals from onset to treatment had significantly more hearing improvements. The route of antioxidant and neurotrophin administration had no impact on treatment effects. CONCLUSION: Both ISP and PSI could be used as salvage treatments for refractory SSNHL. These salvage treatments should be started as soon as possible once SSNHL patients fail a conventional treatment.

Identification and clinical validation of gene signatures with grade and survival in head and neck carcinomas.

This study aimed to explore gene expression profiles that drive malignancy from low- to high-grade head and neck carcinomas (HNC), as well as to analyze their correlations with survival. Gene expressions and clinical data of HNC were downloaded from the Gene Expression Omnibus (GEO) repository. The significantly differential genes (SDGs) between low- and high-grade HNC were screened. Cox regressions were performed to identify prognostic SDGs of progression-free survival (PFS) and disease-specific survival (DSS). The genes were experimentally validated by RT-PCR in clinical tissue specimens. Thirty-five SDGs were identified in 47 low-grade and 30 high-grade HNC samples. Cox regression analyses showed that CXCL14, SLC44A1, and UBD were significantly associated with DSS, and PPP2R2C and SLC44A1 were associated with PFS. Patients were grouped into high-risk or low-risk groups for prognosis based on gene signatures. High-risk patients had significantly shorter DSS and PFS than low-risk patients (P=0.033 and P=0.010, respectively). Multivariate Cox regression showed HPV (P=0.033), lymph node status (P=0.032), and residual status (P<0.044) were independent risk factors for PFS. ROC curves showed the risk score had better efficacy to predict survival both for DSS and PFS (AUC=0.858 and AUC=0.901, respectively). The results showed CXCL14 and SLC44A1 were significantly overexpressed in the low-grade HNC tissues and the UBD were overexpressed in the high-grade HNC tissues. Our results suggested that SDGs had different expression profiles between the low-grade and high-grade HNC, and these genes may serve as prognostic biomarkers to predict survival.

Glucocorticoids protect HEI-OC1 cells from tunicamycin-induced cell damage via inhibiting endoplasmic reticulum stress.

BACKGROUND: To analyze mechanisms of action of glucocorticoid treatment for endoplasmic reticulum stress (ERS) in sensorineural hearing loss (SNHL), we aimed to evaluate the expression and activation status of the protein kinase RNA-like ER kinase (PERK)-C/EBP homologous protein (CHOP) pathway, which is the major pathway in the ERS. METHODS: In the present study, we established an in vitro ERS model using tunicamycin-treated hair-cell-like HEI-OC1 cells. The effect of dexamethasone on proliferation inhibition, apoptosis, and ATF4-CHOP pathway in HEI-OC1 cells was examined by CCK-8 assay, flow cytometry, western blotting, and reverse transcription PCR, respectively. RESULTS: In HEI-OC1 cells, dexamethasone was shown to significantly reduce the tunicamycin-induced expression of ATF4 and CHOP in the context of sustained viability and proliferation, a therapeutic effect that was reversible by co-treatment with a glucocorticoid antagonist. CONCLUSION: Dexamethasone can protect hair-cell-like HEI-OC1 cells from ERS damage, which may be one of the mechanisms of action for GCs in SNHL treatment.

Two New Coordination Polymers: Selective Detection of Cu(II) Ion and Treatment Activity on Inner Ear Damage.

In the current study, on the basis of 1,3,5-tris(2-methylimidazol-1-yl)benzene (timb), a designed tripodal connector, two new transition metal coordination polymers (CPs), {[Cu4(timb)2(Br-IPA)4]·5H2O}n (1) and {[Zn(timb)0.5(NH2-IPA)]·4H2O}n (2) have been generated with the mixed ligand method by the reaction between the timb and corresponding metal salts in the existence of dissimilar functional isophthalic acid (H2IPA) ligands. Furthermore, the Zn(II)-based complex 2 displays high sensitivity in the detection of Cu(II) ion in water. The neural stem cells proliferation after treated via compounds was detected with Cell Counting Kit-8 detection assay. And the real time reverse transcription polymerase chain reaction was carried out for the investigation of the differentiation function of the neural stem cells after the compound 1 treatment and compound 2 treatment. Further, molecular docking simulations confirmed that the biological activity that has been observed from experiments were from the carboxyl group on the Cu complex, in contrast, the imidazole groups were only used for binding with the Cu metal ion to retain the complex structure.

Nuclear Factor Erythroid 2-Related Factor 2-Histone Deacetylase 2 Pathway in the Pathogenesis of Refractory Sudden Sensorineural Hearing Loss and Glucocorticoid Resistance.

INTRODUCTION: A significant number of sensorineural hearing loss (SSNHL) patients had no noticeable hearing improvement after glucocorticoid (GC) treatment. In the present study, we examined expression of the nuclear factor erythroid 2-related factor 2 (NRF2) and histone deacetylase 2 (HDAC2) in peripheral blood mononuclear cells (PBMCs) of refractory SSNHL patients to study the role of NRF2-HDAC2 pathway in GC insensitivity hearing improvement after GC treatment, which is usually referred to as refractory SSNHL or GC insensitivity. MATERIALS AND METHODS: Forty-four refractory SSNHL patients were treated by intratympanic GC infusion. Hearing was tested in all patients before and after treatment by pure tone hearing test. NRF2/HDAC2 mRNA and protein levels were examined in PBMCs of refractory SSNHL patients before and after treatment. PBMCs from healthy volunteers were used as normal controls. RESULTS: According to the hearing improvement after treatment, patients were assigned into 2 groups: the intratympanic GC sensitive (IGCS) group (hearing recovery ≥15 dB HL) and the intratympanic GC insensitive (IGCI) group (hearing recovery <15 dB HL). Before treatment, the NRF2 mRNA level was lower in all patients than the normal control group. After treatment, NRF2 and HDAC2 mRNA and protein levels were increased in the IGCS group, while no significant change was observed in the IGCI group. CONCLUSION: Low response of NRF2/HDAC2 proteins is associated with GC insensitivity in SSNHL. We speculate that the NRF2-HDAC2 pathway affects GC sensitivity in SSNHL patients.

Elucidation of the Hdac2/Sp1/miR-204-5p/Bcl-2 axis as a modulator of cochlear apoptosis via in vivo/in vitro models of acute hearing loss.

We previously reported that dysregulation of histone deacetylase 2 (Hdac2) was associated with the prognosis of sudden sensorineural hearing loss. However, the underlying molecular mechanisms are poorly understood. In the present study, we developed an acute hearing loss animal model in guinea pigs by infusing lipopolysaccharides (LPS) into the cochlea and measured the expression of Hdac2 in the sensory epithelium. We observed that the level of Hdac2 was significantly decreased in the LPS-infused cochleae. The levels of apoptosis-inhibition genes Bcl-2 and Bcl-xl were also decreased in the cochlea and correlated positively with the levels of Hdac2. Caspase3 or TUNEL-positive spiral ganglion neurons, hair cells, and supporting cells were observed in the LPS-infused cochleae. These in vivo observations were recapitulated in cell culture experiments. Based on bioinformatics analysis, we found miR-204-5p was engaged in the regulation of Hdac2 on Bcl-2. Molecular mechanism experiments displayed that miR-204-5p could be regulated by Hdac2 through interacting with transcription factor Sp1. Taken together, these results indicated that the Hdac2/Sp1/miR-204-5p/Bcl-2 regulatory axis mediated apoptosis in the cochlea, providing potential insights into the progression of acute hearing loss. To our knowledge, the study describes a miRNA-related mechanism for Hdac2-mediated regulation in the cochlea for the first time.

Identification and clinical validation of gene signatures with grade and survival in head and neck carcinomas

This study aimed to explore gene expression profiles that drive malignancy from low- to high-grade head and neck carcinomas (HNC), as well as to analyze their correlations with survival. Gene expressions and clinical data of HNC were downloaded from the Gene Expression Omnibus (GEO) repository. The significantly differential genes (SDGs) between low- and high-grade HNC were screened. Cox regressions were performed to identify prognostic SDGs of progression-free survival (PFS) and disease-specific survival (DSS). The genes were experimentally validated by RT-PCR in clinical tissue specimens. Thirty-five SDGs were identified in 47 low-grade and 30 high-grade HNC samples. Cox regression analyses showed that CXCL14, SLC44A1, and UBD were significantly associated with DSS, and PPP2R2C and SLC44A1 were associated with PFS. Patients were grouped into high-risk or low-risk groups for prognosis based on gene signatures. High-risk patients had significantly shorter DSS and PFS than low-risk patients (P=0.033 and P=0.010, respectively). Multivariate Cox regression showed HPV (P=0.033), lymph node status (P=0.032), and residual status (P<0.044) were independent risk factors for PFS. ROC curves showed the risk score had better efficacy to predict survival both for DSS and PFS (AUC=0.858 and AUC=0.901, respectively). The results showed CXCL14 and SLC44A1 were significantly overexpressed in the low-grade HNC tissues and the UBD were overexpressed in the high-grade HNC tissues. Our results suggested that SDGs had different expression profiles between the low-grade and high-grade HNC, and these genes may serve as prognostic biomarkers to predict survival.

Differential Levels of Endoplasmic Reticulum Stress in Peripheral Blood Mononuclear Cells from Patients with Sudden Sensorineural Hearing Loss.

BACKGROUND Sudden sensorineural hearing loss (SSNHL) is currently treated with a combination of drugs, predominantly with glucocorticoids (GCs). However, the mechanisms of action of GCs in SSNHL are unknown. This study aimed to analyze the role of endoplasmic reticulum stress (ERS) in SSNHL pathogenesis and prognosis. MATERIAL AND METHODS In this study, we evaluated the expression and activation status of the protein kinase RNA-like endoplasmic reticulum kinase (PERK)-C/EBP homologous protein (CHOP) pathway in peripheral blood mononuclear cells (PBMCs) from patients with SSNHL and compared them with those in healthy controls. We also compared differences in expression of activating transcription factor 4 (ATF4) and CHOP before and after glucocorticoid treatment in patients with improved and unimproved SSNHL. RESULTS Treatment with GCs significantly improved hearing in 55% of patients with SSNHL. Levels of phosphorylated PERK (p-PERK) and phosphorylated eukaryotic initiation factor 2alpha were increased in PBMCs from patients with SSNHL compared with healthy controls. ATF4 and CHOP expression were also significantly elevated. After treatment, the amount of ATF4 and CHOP proteins in PBMCs in the patients whose SSNHL improved was significantly reduced compared with the levels measured before treatment in all patients with SSNHL. The expression of the ATF4 and CHOP proteins in PBMCs in the unimproved group, however, was not significantly changed relative to pretreatment levels. CONCLUSIONS ERS may play a significant role in the pathogenesis of SSNHL, and the responsiveness of the condition to GC-mediated mitigation of ERS may be one of the key factors that affect patient prognosis.

Panax notoginseng Saponins protect auditory cells against cisplatin­induced ototoxicity by inducing the AKT/Nrf2 signaling­mediated redox pathway.

Cisplatin­induced cytotoxicity, such as nephrotoxicity, neurotoxicity and ototoxicity, restricts the clinical application of this compound. Panax notoginseng Saponins (PNS) exhibit potent free radical scavenging and antioxidant activity. PNS have been demonstrated to reduce cisplatin­induced nephrotoxicity and neurotoxicity. The present study investigated the ability of PNS to protect the auditory HEI­OC1 cell line against ototoxicity induced by cisplatin. PNS induced activation of the AKT/nuclear factor erythroid 2­related factor 2 (Nrf2) signaling pathway. Following pretreatment with PNS, HEI­OC1 cells were treated with cisplatin and cultured for 24 h. The viability of HEI­OC1 cells was examined using a Cell Counting Kit­8 assay. Double staining analysis was used to measure cell apoptosis. The ability of PNS to reduce reactive oxygen species (ROS) levels was assessed by flow cytometry. The levels of phosphorylated (p)­AKT, heme oxygenase 1 (HO­1), NAD(P)H quinone dehydrogenase 1 (NQO1), glutamate­cysteine ligase catalytic (GCLC) and Nrf2 were measured by western blotting. HEI­OC1 cells that were pretreated with PNS exhibited significantly increased cell viability compared with that noted in cells treated only with cisplatin. In addition, PNS suppressed the induction of apoptosis and ROS production following cisplatin treatment. The upregulation of NQO1, HO­1 and GCLC expression in PNS­pretreated cells was associated with p­AKT levels and the activation of Nrf2. These findings suggested that PNS protected auditory cells against ototoxicity induced by cisplatin by activating AKT/Nrf2 signaling. PNS may serve as a potential candidate in regulating cisplatin­induced cytotoxicity.

Response of Glucocorticoid Receptor Alpha and Histone Deacetylase 2 to Glucocorticoid Treatment Predicts the Prognosis of Sudden Sensorineural Hearing Loss.

OBJECTIVES: To investigate glucocorticoid receptor (GR) and histone deacetylase 2 (HDAC2) gene expression and protein levels in peripheral blood mononuclear cells (PBMCs) of patients with severe or profound sudden sensorineural hearing loss (SSNHL) and to explore the roles of GRs and HDAC2 in glucocorticoid (GC) insensitivity. METHODS: Fifty-five severe or profound SSNHL patients were enrolled in the study. According to hearing improvement after GC treatment, patients were assigned into two groups: GC-sensitive and GC-resistant. A normal reference group included 20 healthy volunteers without hearing loss. Quantitative real-time polymerase chain reaction and Western blot analyses were used to detect the relative expression of GRα, GRß, and HDAC2 in PBMCs at the mRNA and protein levels. RESULTS: The protein levels of GRs and HDAC2 in PBMCs of SSNHL patients were lower than the normal reference values before GC treatment. Compared with the GC-resistant group, both the mRNA and protein levels of GRα and HDAC2 were significantly increased in the GC-sensitive group after GC treatment. CONCLUSION: A lack of GRα and HDAC2 induction following steroid treatment in GC-resistant SSNHL patients may play a fundamental mechanistic role in GC insensitivity. Response of GRα and HDAC2 to steroid treatment may, thus, predict the prognosis of hearing improvement in SSNHL patients.

Aminophylline restores glucocorticoid sensitivity in a guinea pig model of sudden sensorineural hearing loss induced by lipopolysaccharide.

Glucocorticoids have been used to treat hearing loss and vestibular dysfunction for many years. However, some reports have indicated that a subset of patients with these disorders exhibit glucocorticoid insensitivity or resistance. A reduction in histone deacetylase 2 (HDAC2) activity and expression has been reported to play a critical role in glucocorticoid resistance. Here, we investigated the protective effects of aminophylline on HDAC2 expression and glucocorticoid sensitivity in lipopolysaccharide (LPS)-induced sudden sensorineural hearing loss in guinea pigs. We assessed hearing recovery in LPS-applied guinea pigs, which were either left untreated or were systemically treated with either dexamethasone, aminophylline, or a combination of the two. We utilized fluorescence microscopy and enzyme-linked immunosorbent assay to analyze the distribution patterns of HDAC2 and detect its levels in the cochlea. We used hematoxylin-eosin staining to examine cochlear histopathological changes. In the absence of treatment, significant hearing loss was detected in LPS-exposed animals. A synergistic effect was observed between aminophylline and dexamethasone in maintaining HDAC2 expression levels, preventing hearing loss in LPS-exposed animals and reducing cochlear damage. This study indicates that aminophylline can restore glucocorticoid sensitivity, which provides a new approach to treating patients with hearing disorders who are refractory to glucocorticoids.

Histone Deacetylase 2 in Sudden Sensorineural Hearing Loss Patients in Response to Intratympanic Methylprednisolone Perfusion.

OBJECTIVE: To evaluate the expression of histone deacetylase 2 (HDAC2) in peripheral blood mononuclear cells (PBMCs) from patients with sudden sensorineural hearing loss (SSNHL) who were refractory to systemic glucocorticoid treatment and to identify the relationship between the level of HDAC2 and glucocorticoid insensitivity. STUDY DESIGN: Prospective clinical study. SETTING: This study was conducted in Nanjing Drum Tower Hospital, Nanjing University Medical School. SUBJECTS AND METHODS: PBMCs were collected from 42 refractory SSNHL patients. After a 10-day intratympanic methylprednisolone perfusion (IMP) and systemic Ginkgo biloba extract treatment, the SSNHL patients were divided into 2 groups according to their hearing recovery after IMP (IMP sensitive and insensitive). Real-time polymerase chain reaction and HDAC2 protein assays were used to detect the relative expression levels of HDAC2 in PBMCs. The HDAC2 mRNA expression and protein levels in PBMCs collected from 17 volunteers were used as normal HDAC2 reference levels. RESULTS: Compared with normal reference levels, HDAC2 protein levels were significantly reduced, while the HDAC2 mRNA expression was much higher in all refractory SSNHL patients before IMP. HDAC2 mRNA expression and HDAC2 protein levels were significantly elevated in the IMP-sensitive group, while no change was observed in the IMP-insensitive group after IMP plus systemic antioxidant treatment. CONCLUSIONS: Reduced HDAC2 protein levels may be 1 of the mechanistic underpinnings of corticosteroid insensitivity in refractory SSNHL patients. IMP can increase HDAC2 protein levels and the expression of HDAC2 mRNA in IMP-sensitive patients. HDAC2 protein levels might be regulated through posttranslational modifications.