Deferoxamine protects cochlear hair cells and hair cell-like HEI-OC1 cells against tert-butyl hydroperoxide-induced ototoxicity

Oxidative stress is the common mechanism of sensorineural hearing loss (SNHL) caused by many factors, such as noise, drugs and ageing. Here, we used tert-butyl hydroperoxide (t-BHP) to cause oxidative stress damage in HEI-OC1 cells and in an in vitro cochlear explant model. We observed lipid peroxidation, iron accumulation, mitochondrial shrinkage and vanishing of mitochondrial cristae, which caused hair cell ferroptosis, after t-BHP exposure. Moreover, the number of TUNEL-positive cells in cochlear explants and HEI-OC1 cells increased significantly, suggesting that t-BHP caused the apoptosis of hair cells. Administration of deferoxamine (DFOM) significantly attenuated t-BHP-induced hair cell loss and disordered hair cell arrangement in cochlear explants as well as HEI-OC1 cell death, including via apoptosis and ferroptosis. Mechanistically, we found that DFOM treatment reduced t-BHP-induced lipid peroxidation, iron accumulation and mitochondrial pathological changes in hair cells, consequently mitigating apoptosis and ferroptosis. Moreover, DFOM treatment alleviated GSH depletion caused by t-BHP and activated the Nrf2 signalling pathway to exert a protective effect. Furthermore, we confirmed that the protective effect of DFOM mainly depended on its ability to chelate iron by constructing Fth1 knockout (KO), TfR1 KO and Nrf2 KO HEI-OC1 cell lines using CRISPR/Cas9 technology and a Flag-Fth1 (overexpression) HEI-OC1 cell line using the FlpIn™ System. Our findings suggest that DFOM is a potential drug for SNHL treatment due to its ability to inhibit apoptosis and ferroptosis by chelating iron and scavenging reactive oxygen species (ROS).

Correlation between clinical characteristics and tinnitus severity in tinnitus patients of different sexes: an analytic retrospective study

PURPOSE

This study aimed to explore whether sex is influences tinnitus severity and whether the risk factors for tinnitus severity are the same in tinnitus patients of different sexes.

METHODS

This was a retrospective study of data from 1427 patients complaining of tinnitus in a local hospital otolaryngology clinic from November 2019 to January 2022. All patients were interviewed and assessed by otoscopy, pure-tone audiometry, tinnitus handicap inventory (THI), visual analogue scale (VAS), and tinnitus refinement test.

RESULTS

THI values were higher in females than in males (P = 0.00). Types of tinnitus sounds (OR 0.667, P = 0.000) and degree of hearing loss (OR 1.318, P = 0.000) were risk factors for tinnitus severity in males. Types of tinnitus sounds (OR 0.789, P = 0.005), sensation level (OR 1.023, P = 0.037), tinnitus types (OR 1.163, P = 0.041), tinnitus location (OR 1.198, P = 0.026), and the degree of hearing loss (OR 1.303, P = 0.000) were risk factors for tinnitus severity in females. Sex was an influencing factor for tinnitus severity. There were different risk factors for the tinnitus severity in different sexes.

CONCLUSION

The risk factors for tinnitus severity differed according to sex in tinnitus patients, and the risk factors for tinnitus severity were greater in women than in men. These findings add to the literature on sex differences in tinnitus and suggest that medical and psychological screening of affected individuals and customized tinnitus treatment for each individual with tinnitus are needed.

TRIAL REGISTRATION NUMBER/DATE OF REGISTRATION

ChiCTR2200057958, 2022/3/24 (retrospectively registered trials).

Treatment with the Ferroptosis Inhibitor Ferrostatin-1 Attenuates Noise-Induced Hearing Loss by Suppressing Ferroptosis and Apoptosis

Hair cell death induced by excessive reactive oxygen species (ROS) has been identified as the major pathogenesis of noise-induced hearing loss (NIHL). Recent studies have demonstrated that cisplatin- and neomycin-induced ototoxicity can be alleviated by ferroptosis inhibitors. However, whether ferroptosis inhibitors have a protective effect against NIHL remains unknown. We investigated the protective effect of the ferroptosis inhibitor ferrostatin-1 (Fer-1) on NIHL in vivo in CBA/J mice and investigated the protective effect of Fer-1 on tert-butyl hydroperoxide (TBHP)-induced hair cell damage in vitro in cochlear explants and HEI-OC1 cells. We observed ROS overload and lipid peroxidation, which led to outer hair cell (OHC) apoptosis and ferroptosis, in the mouse cochlea after noise exposure. The expression level of apoptosis-inducing factor mitochondria-associated 2 (AIFM2) was substantially increased following elevation of the expression of its upstream protein P53 after noise exposure. The ferroptosis inhibitor Fer-1was demonstrated to enter the inner ear after the systemic administration. Administration of Fer-1 significantly alleviated noise-induced auditory threshold elevation and reduced the loss of OHCs, inner hair cell (IHC) ribbon synapses, and auditory nerve fibers (ANFs) caused by noise. Mechanistically, Fer-1 significantly reduced noise- and TBHP-induced lipid peroxidation and iron accumulation in hair cells, alleviating ferroptosis in cochlear cells consequently. Furthermore, Fer-1 treatment decreased the levels of TfR1, P53, and AIFM2. These results suggest that Fer-1 exerted its protective effects by scavenging of ROS and inhibition of TfR1-mediated ferroptosis and P53-AIFM2 signaling pathway-mediated apoptosis. Our findings suggest that Fer-1 is a promising drug for treating NIHL because of its ability to inhibit noise-induced hair cell apoptosis and ferroptosis, opening new avenues for the treatment of NIHL.

Systemic steroid administration combined with intratympanic steroid injection in the treatment of a unilateral sudden hearing loss prognosis prediction model: A retrospective observational study

Idiopathic sudden sensorineural hearing loss (ISSNHL) is an emergency ear disease that is referred to as a sensorineural hearing loss of at least 30 dB in three sequential frequencies and occurs over a period of < 72 h. Because of its etiology, pathogenesis, and prognostic factors, the current treatment methods are not ideal. Previous studies have developed prognostic models to predict hearing recovery from ISSNHL, but few studies have incorporated serum biochemical indicators into previous models. The aim of this study was to explore the factors influencing the ISSNHL prognosis of combination therapy (combined intratympanic and systemic use of steroids, CT), among the patient population data, the serum biochemical indicators before the treatment, and the clinical features of ISSNHL. The new prediction model was developed through these factors. From November 2015 to April 2022, 430 patients who underwent CT at the Department of Otorhinolaryngology Head and Neck Surgery, Tangdu Hospital, Air Force Medical University for ISSNHL, were reviewed retrospectively. We found significant differences in age (P = 0.018), glucose (P = 0.035), white blood cell (WBC) (P = 0.021), vertigo (P = 0.000) and type (P = 0.000) with different therapeutic efficacies. Multivariate logistic regression analysis showed that age (OR = 0.715, P = 0.023), WBC (OR = 0.527, P = 0.01), platelet to lymphocyte ratio (PLR) (OR = 0.995, P = 0.038), vertigo (OR = 0.48, P = 0.004), course (time from onset to treatment) (OR = 0.681, P = 0.016) and type (OR = 0.409, P = 0.000) were independent risk factors for ISSNHL prognosis. Based on independent risk factors, a predictive model and nomogram were developed to predict hearing outcomes in ISSNHL patients. The area under the curve (AUC) value of the model developed in this study was 0.773 (95% CI = 0.730–0.812), which has a certain predictive ability. The calibration curve indicated good consistency between the actual diagnosed therapeutic effectiveness and the predicted probability. The model and nomogram can predict the hearing prognosis of ISSNHL patients treated with CT and can provide help for medical staff to make the best clinical decision. This study has been registered with the registration number ChiCTR2200061379.

mito-TEMPO Attenuates Oxidative Stress and Mitochondrial Dysfunction in Noise-Induced Hearing Loss via Maintaining TFAM-mtDNA Interaction and Mitochondrial Biogenesis

The excessive generation of reactive oxygen species (ROS) and mitochondrial damage have been widely reported in noise-induced hearing loss (NIHL). However, the specific mechanism of noise-induced mitochondrial damage remains largely unclear. In this study, we showed that acoustic trauma caused oxidative damage to mitochondrial DNA (mtDNA), leading to the reduction of mtDNA content, mitochondrial gene expression and ATP level in rat cochleae. The expression level and mtDNA-binding function of mitochondrial transcription factor A (TFAM) were impaired following acoustic trauma without affecting the upstream PGC-1α and NRF-1. The mitochondria-target antioxidant mito-TEMPO (MT) was demonstrated to enter the inner ear after the systemic administration. MT treatment significantly alleviated noise-induced auditory threshold shifts 3d and 14d after noise exposure. Furthermore, MT significantly reduced outer hair cell (OHC) loss, cochlear ribbon synapse loss, and auditory nerve fiber (ANF) degeneration after the noise exposure. In addition, we found that MT treatment effectively attenuated noise-induced cochlear oxidative stress and mtDNA damage, as indicated by DHE, 4-HNE, and 8-OHdG. MT treatment also improved mitochondrial biogenesis, ATP generation, and TFAM-mtDNA interaction in the cochlea. These findings suggest that MT has protective effects against NIHL via maintaining TFAM-mtDNA interaction and mitochondrial biogenesis based on its ROS scavenging capacity.

Whole genome expression profiling of hepatitis B virus-transfected cell line reveals the potential targets of anti-HBV drugs

Hepatitis B virus (HBV) infection is a major health concern world wide, and few effective treatments have been developed. It has recently been reported that inhibiting host-cell proteins can prevent viral infection. The human genome may contain more genes required for HBV infection and replication than the viral genome. A systematic approach to find these potential antiviral targets is by host gene expression analysis using DNA microarrays. The aim of this study was to identify and validate novel cellular anti-HBV targets. The Human Whole Genome Bioarray was used to analyze differentially expressed genes in HepG2.2.15 cells and HepG2 cells. Altered gene expression in HepG2.2.15 cells was studied following treatment with the anti-HBV drug, lamivudine. Genes that were differentially expressed during HBV infection and reversed with anti-HBV drugs were validated by semiquantitative reverse transcription-PCR. Bioinformatics analysis revealed ABHD2, EREG, ACVR2B, CDC34, KHDRBS3 and RORA as potential cellular anti-HBV targets. Antisense oligodeoxynucleotides were used to test the antiviral activity of these potential targets. Results strongly suggested that inhibition of ABHD2 or EREG significantly blocked HBV propagation in HepG2.2.15 cells. This study demonstrates that ABHD2 and EREG are essential for HBV propagation and provides strong evidence that these proteins could be used as potential targets for anti-HBV drugs.

Antisense oligonucleotides targeted against asialoglycoprotein receptor 1 block human hepatitis B virus replication

Chronic hepatitis B virus (HBV) infection is a major worldwide public health problem. Better therapeutics and treatment strategies are urgently needed because of ineffective clinical treatment. Our previous study showed that asialoglycoprotein receptor 1 (ASGPR1) was upregulated by HBV but downregulated by lamivudine in HepG2.2.15 cells. It has also been reported that ASGPR is a candidate receptor for HBV attachment to hepatocytes. Therefore, as a major subunit of ASGPR, ASGPR1, might be a potential target for anti-HBV drugs. To validate this hypothesis, antisense oligonucleiotides (ASODNs) were used to downregulate ASGPR1 level in HepG2.2.15 cells. By using the MFOLD web server and BLAST searches, five ASODNs theoretically targeting ASGPR1 were selected. After 72 h post-transfection, HBV-DNA level in cell medium were examined by real-time polymerase chain reaction (PCR). Hepatitis B surface antigen (HBsAg) and Hepatitis B e antigen (HBeAg) were detected using enzyme-linked immunosorbent assay (ELISA). ASGPR1 mRNA and protein level were measured by semi-quantitative reverse transcriptase (RT)-PCR and Western blot analysis respectively. The results showed that ASODN2 significantly downregulated ASGPR1 level. It also reduced HBV-DNA, HBsAg and HBeAg level in cell medium as observed with lamivudine. In contrast, the sense sequence and scrambled sequence of ASODN2 had no effect on ASGPR1 and HBV markers in HepG2.2.15 cells. This indicated that ASODN2 could specifically reduce HBV replication in vitro. Additionally, cell proliferation and apoptosis assay suggested that downregulation of ASGPR1 did not affect cell viability. We, therefore, proposed that ASODNs targeted against ASGPR1 could block HBV replication without the influence of other changes, and ASGPR1 could be targeted for anti-HBV drug development.

Hemodynamic effect of norepinephrine and serotonin with and without indomethacin

Injections of serotonin (5-HT) into the aortic arch of rats caused greater reductions of blood pressure (BP) and less increases in renal vascular resistance (RVR) than that into jugular veins, in contrast to norepinephrine (NE) which tended to cause larger increases in BP and RVR by the intra-aortic route. Indomethacin (INDO) enhanced renal vasoconstrictor responses to NE, but did not affect those of 5-HT. These data support a central nervous system (CNS) hypotensive effect of 5-HT not shared by NE, and a less interaction with vasodilator prostaglandins for 5-HT, when compared with NE.

Serotonin and 5-hydroxytryptophan on blood pressure and renal blood flow in anesthetized rats

The effects of exogenous (injected) serotonin on mean blood pressure and renal blood flow in male Sprague-Dawley rats were compared with the effects of enhanced endogenous serotonin, accomplished by injections of 5-hydroxytryptophan (5-HTP). Responses were evaluated with and without carbidopa, which blocks peripheral conversion of 5-HTP to serotonin, and with and without indomethacin to assess the contribution of prostanoids. Both serotonin (0.25-1.0 micrograms) and 5-HTP (50-200 micrograms) decreased blood pressure and renal blood flow and increased renal vascular resistance in dose-dependent fashion. Hypotensive responses with both agents were greater after arterial injections into the aortic arch than after intravenous injections (into the jugular vein). Carbidopa had no significant effects on responses to serotonin but ablated the ability of 5-HTP to increase renal vascular resistance and decrease renal blood flow. Carbidopa did not alter the hypotensive action of 5-HTP. Indomethacin had no significant effect on responses to serotonin or 5-HTP. These results support a direct renal vasoconstrictor effect for exogenous and endogenously formed serotonin and a hypotensive effect probably arising in the central nervous system.