Astaxanthine attenuates cisplatin ototoxicity in vitro and protects against cisplatin-induced hearing loss in vivo

Atomically dispersed copper(I) on tungstosilicic acid for catalytic protection against cisplatin-induced hearing loss

The employment of platinum-based drugs for cancer chemotherapy, which might yield oxidative stress, is regarded as one main factor leading to hearing loss. The exact molecular mechanisms for cisplatin-induced hearing loss require further clarification, thus limiting the development of FDA-approved therapies. Herein, we mimicked the molecular structure of natural antioxidative enzymes to fabricate a four-oxygen-coordinating copper single-atom nanozyme (Cu SAN) exhibiting good superoxide dismutase and catalase activity, to alleviate the oxidative stress induced by platinum-based drugs. Notably, Cu SAN exhibited profound protective effects against cisplatin-induced hair cell damage with only 15 ng mL-1 of Cu species, successfully reversing cisplatin-induced hearing loss via oral administration. Due to its oxidation resistance, pretreatment with Cu SAN significantly improved cell viability and reduced ROS accumulation in cisplatin-triggered hair cell damage in HEI-OC1 cells and cochlear explants. Our results first demonstrated that cisplatin treatment induced cuproptosis in hair cells by modulating copper ion homeostasis. Further investigation revealed that Cu SAN nanozyme effectively alleviated hair cell cuproptosis by regulating FDX1 and reducing aggregated lipoacylated protein. This research underscores the promising potential of four-oxygen-coordinating Cu nanomaterials as a therapeutic approach to combat hearing loss, providing a new strategy for auditory protection.

The Antioxidant Ergothioneine Alleviates Cisplatin-Induced Hearing Loss Through the Nrf2 Pathway

Aims: Cisplatin (CDDP) is a commonly used chemotherapeutic agent for treating head and neck tumors. However, there is high incidence of ototoxicity in patients treated with CDDP, which may be caused by the excessive reactive oxygen species (ROS) generation in the inner ear. Many studies have demonstrated the strong antioxidant effects of ergothioneine (EGT). Therefore, we assumed that EGT could also attenuate cisplatin-induced hearing loss (CIHL) as well. However, the protective effect and mechanism of EGT on CIHL have not been elucidated as so far. In this study, we investigated whether EGT could treat CIHL and the mechanism. Results: In our study, we confirmed the protective effect of EGT on preventing CDDP-induced toxicity both in vitro and in vivo. The auditory brainstem response threshold shift in the EGT + CDDP treatment mice was 30 dB less than that in the CDDP treatment mice. EGT suppressed production of ROS and proapoptotic proteins both in tissue and cells. By silencing nuclear factor erythroid 2-related factor 2 (Nrf2), we confirmed that EGT protected against CIHL via the Nrf2 pathway. We also found that SLC22A4 (OCTN1), an important molecule involved in transporting EGT, was expressed in the cochlea. Innovation: Our results revealed the role of EGT in the prevention of CIHL by activating Nrf2/HO-1/NQO-1 pathway, and broadened a new perspective therapeutic target of EGT. Conclusion: EGT decreased ROS production and promoted the expression of antioxidative enzymes to maintain redox homeostasis in sensory hair cells. Overall, our results indicated that EGT may serve as a novel treatment drug to attenuate CIHL. Antioxid. Redox Signal. 42, 97-114.

Cisplatin-Induced Hearing Loss, Oxidative Stress, and Antioxidants as a Therapeutic Strategy-A State-of-the-Art Review

Cisplatin is an established component of treatment protocols for various solid malignancies but carries a significant potential for serious adverse effects. Ototoxicity from cisplatin treatment is an important dose-limiting toxicity that manifests as bilateral, progressive, irreversible, dose-dependent sensorineural hearing loss, ear pain, tinnitus, and vestibular dysfunction. Despite the recent approval of sodium thiosulphate for the prevention of cisplatin-induced hearing loss (CIHL) in pediatric patients, structured prevention programs are not routinely implemented in most hospitals, and reducing platinum-induced ototoxicity in adults remains an important clinical problem without established treatment options. Cochlear oxidative stress plays a fundamental role in CIHL. Here, we review the molecular mechanisms leading to oxidative stress in CIHL and the clinical and preclinical studies testing antioxidants in CIHL to guide future clinical trials in assessing the efficacy and safety of candidate antioxidant compounds in this clinical setting.

Application of self-assembly palladium single-atom nanozyme over polyoxometalates in protection against neomycin-induced hearing loss by inhibiting ferroptosis

Deafness mainly results from irreversible impairment of hair cells (HCs), which may relate to oxidative stress, yet therapeutical solutions is lacked due to limited understanding on the exact molecular mechanism. Herein, mimicking the molecular structure of natural enzymes, a palladium (Pd) single-atom nanozyme (SAN) was fabricated, exhibiting superoxide dismutase and catalase activity, transforming reactive oxygen species (ROS) into O2 and H2O. We examined the involvement of Pd in neomycin-induced HCs loss in vitro and in vivo over zebrafish. Our results revealed that neomycin treatment induced apoptosis in HCs, resulting in substantial of ROS elevation in HEI-OC1 cells, decrease in mitochondrial membrane potential, and increase in lipid peroxidation and iron accumulation, ultimately leading to iron-mediated cell death. Noteworthy, Pd SAN treatment exhibited significant protective effects against HCs damage and impaired HCs function in zebrafish by inhibiting ferroptosis. Furthermore, the application of iron death inducer RSL3 resulted in notable exacerbation of neomycin-induced harm, which was mitigated by Pd administration. Our investigation demonstrates that antioxidants is promising for inhibiting ferroptosis and repairing of mitochondrial function in HCs and the enzyme-mimic SAN provides a good strategy for designing drugs alleviating neomycin-induced ototoxicity.

Hesperidin activates Nrf2 to protect cochlear hair cells from cisplatin-induced damage

Cisplatin is widely employed in clinical oncology as an anticancer chemotherapy drug in clinical practice and is known for its severe ototoxic side effects. Prior research indicates that the accumulation of reactive oxygen species (ROS) plays a pivotal role in cisplatin's inner ear toxicity. Hesperidin is a flavanone glycoside extracted from citrus fruits that has anti-inflammatory and antioxidant effects. Nonetheless, the specific pharmacological actions of hesperidin in alleviating cisplatin-induced ototoxicity remain elusive. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is a critical mediator of the cellular oxidative stress response, is influenced by hesperidin. Activation of Nrf2 was shown to have a protective effect against cisplatin-induced ototoxicity. The potential of hesperidin to stimulate Nrf2 in attenuating cisplatin's adverse effects on the inner ear warrants further investigation. This study employs both in vivo and in vitro models of cisplatin ototoxicity to explore this possibility. Our results reveal that hesperidin mitigates cisplatin-induced ototoxicity by activating the Nrf2/NQO1 pathway in sensory hair cells, thereby reducing ROS accumulation, preventing hair cell apoptosis, and alleviating hearing loss.

New application of ombuoside in protecting auditory cells from cisplatin-induced ototoxicity via the apoptosis pathway

Hearing loss is caused by many factors including ototoxic drug-induced hair cell damage. Ombuoside, an antioxidant isolated from Gynostemma pentaphyllum, has been suggested to serve as a new neuroprotective drug. However, the role of ombuoside in protecting inner ear hair cells from ototoxic drug-induced damage has not been investigated. Here, we demonstrated the protective potential of ombuoside in mitigating drug-induced ototoxicity in vivo and in vitro. We used cisplatin, a highly ototoxic anti-tumor drug, to induce hair cell damage. Our results showed that ombuoside significantly increased the survival of cisplatin-treated HEI-OC1 cells. Further mechanism research suggested that ombuoside protects HEI-OCI cells from cisplatin-induced apoptosis by reducing the cisplatin-induced upregulation of apoptosis-promoting proteins Bax, Bak, as well as apoptosis indicator proteins cytochrome C and cleaved-caspase-3, and the downregulation of apoptosis-inhibiting proteins Bcl-2. Ombuoside also protects the cells from the excessive ROS production and mitochondrial membrane depolarization triggered by cisplatin. These results demonstrated the potential for ombuoside in protecting hair cells from cisplatin by suppressing ROS generation and the mitochondrial apoptotic cascade. Ombuoside showed promise in protecting hair cells from cisplatin-induced apoptosis by suppressing ROS generation and the mitochondrial apoptotic cascade. Furthermore, ombuoside co-treatment in mouse cochlear explants and zebrafish lateral neuromasts rescued the decreased number and deformed morphology of hair cells resulting from cisplatin exposure. These findings further validated our conclusions and indicated that ombuoside is a potential protector against hearing loss caused by ototoxicity as a clinical side effect of cisplatin.

PGC-1α-mediated imbalance of mitochondria-lipid droplet homeostasis in neomycin-induced ototoxicity and nephrotoxicity

Ototoxicity and nephrotoxicity are the most prevalent side effects of aminoglycoside antibiotics (gentamicin, amikacin, neomycin) and platinum anti-tumor drugs (cisplatin, carboplatin). The inner ear and kidney share similarities in drug deposition and toxicity, but the underlying pathophysiological mechanisms remain unclear. Investigating the shared mechanisms and metabolic alterations in these distinct organs will provide valuable insights for clinical therapy. A strong correlation has been identified between the spatiotemporal accumulation patterns of neomycin and the specific occurrence of lipid metabolism disorders in these two organs. The primary allocation of neomycin to mitochondria results in a notable escalation in the accumulation of lipid droplets (LDs) and more interactions between mitochondria and LDs, leading to a sequence of disturbances in lipid metabolism, such as increased lipid ROS and the blocked transfer of fatty acids from LDs to mitochondria. PGC-1α deficiency worsens the neomycin-induced disorders in lipid metabolism and intensifies the pathological interactions between mitochondria and LDs, as indicated by the exacerbated disturbance of dynamic LD turnover, increased level of oxidized lipids and decreased use of fatty acids. This investigation provides a fresh perspective on the lipid metabolic dysfunction related to mitochondria-LD interactions in drug-induced ototoxicity and nephrotoxicity, potentially providing novel avenues for intervention strategies.

Apoptosis, autophagy, ferroptosis, and pyroptosis in cisplatin-induced ototoxicity and protective agents

Cisplatin is widely used to treat various solid tumors. However, its toxicity to normal tissues limits its clinical application, particularly due to its ototoxic effects, which can result in hearing loss in patients undergoing chemotherapy. While significant progress has been made in preclinical studies to elucidate the cellular and molecular mechanisms underlying cisplatin-induced ototoxicity (CIO), the precise mechanisms remain unclear. Moreover, the optimal protective agent for preventing or mitigating cisplatin-induced ototoxicity has yet to be identified. This review summarizes the current understanding of the roles of apoptosis, autophagy, ferroptosis, pyroptosis, and protective agents in cisplatin-induced ototoxicity. A deeper understanding of these cell death mechanisms in the inner ear, along with the protective agents, could facilitate the translation of these agents into clinical therapeutics, help identify new therapeutic targets, and provide novel strategies for cisplatin-based cancer treatment.

Nuciferine Protects Cochlear Hair Cells from Ferroptosis through Inhibiting NCOA4-Mediated Ferritinophagy

Cisplatin is a widely used antineoplastic drug for treating various types of cancers. However, it can cause severe side effects, such as bilateral and irreversible hearing loss, which significantly impacts quality of life. Ferroptosis, an iron-dependent form of programmed cell death, has been implicated in the pathogenesis of cisplatin-induced ototoxicity. Here, we investigated the effects of nuciferine, a natural active ingredient isolated from lotus species, on the ferroptosis of cochlear hair cells. Firstly, our results demonstrated that nuciferine can protect hair cells against RSL3-induced and cisplatin-induced damage. Secondly, nuciferine treatment reduced ferrous iron (Fe2+) overload in cochlear hair cells via inhibiting NCOA4-mediated ferritinophagy. Inhibition of ferritinophagy by knocking down Ncoa4 alleviated cisplatin-induced ototoxicity. Importantly, nuciferine treatment mitigated cochlear hair cell loss and damage to ribbon synapse, and improved mouse hearing function in an acute cisplatin-induced hearing loss model. Our findings highlight the role of NCOA4-mediated ferritinophagy in the pathogenesis of cisplatin-induced ototoxicity and provide evidence for nuciferine as a promising protective agent for treating cisplatin-induced hearing loss.

Inhibition of CISD1 attenuates cisplatin-induced hearing loss in mice via the PI3K and MAPK pathways

Cisplatin is an effective chemotherapeutic drug for different cancers, but it also causes severe and permanent hearing loss. Oxidative stress and mitochondrial dysfunction in cochlear hair cells (HCs) have been shown to be important in the pathogenesis of cisplatin-induced hearing loss (CIHL). CDGSH iron sulfur domain 1 (CISD1, also known as mitoNEET) plays a critical role in mitochondrial oxidative capacity and cellular bioenergetics. Targeting CISD1 may improve mitochondrial function in various diseases. However, the role of CISD1 in cisplatin-induced ototoxicity is unclear. Therefore, this study was performed to assess the role of CISD1 in cisplatin-induced ototoxicity. We found that CISD1 expression was significantly increased after cisplatin treatment in both HEI-OC1 cells and cochlear HCs. Moreover, pharmacological inhibition of CISD1 with NL-1 inhibited cell apoptosis and reduced mitochondrial reactive oxygen species accumulation in HEI-OC1 cells and cochlear explants. Inhibition of CISD1 with small interfering RNA in HEI-OC1 cells had similar protective effects. Furthermore, NL-1 protected against CIHL in adult C57 mice, as evaluated by the auditory brainstem response and immunofluorescent staining. Mechanistically, RNA sequencing revealed that NL-1 attenuated CIHL via the PI3K and MAPK pathways. Most importantly, NL-1 did not interfere with the antitumor efficacy of cisplatin. In conclusion, our study revealed that targeting CISD1 with NL-1 reduced reactive oxygen species accumulation, mitochondrial dysfunction, and apoptosis via the PI3K and MAPK pathways in HEI-OC1 cell lines and mouse cochlear explants in vitro, and it protected against CIHL in adult C57 mice. Our study suggests that CISD1 may serve as a novel target for the prevention of CIHL.

Natural products as non-covalent and covalent modulators of the KEAP1/NRF2 pathway exerting antioxidant effects

By controlling several antioxidant and detoxifying genes at the transcriptional level, including NAD(P)H quinone oxidoreductase 1 (NQO1), multidrug resistance-associated proteins (MRPs), UDP-glucuronosyltransferase (UGT), glutamate-cysteine ligase catalytic (GCLC) and modifier (GCLM) subunits, glutathione S-transferase (GST), sulfiredoxin1 (SRXN1), and heme-oxygenase-1 (HMOX1), the KEAP1/NRF2 pathway plays a crucial role in the oxidative stress response. Accordingly, the discovery of modulators of this pathway, activating cellular signaling through NRF2, and targeting the antioxidant response element (ARE) genes is pivotal for the development of effective antioxidant agents. In this context, natural products could represent promising drug candidates for supplementation to provide antioxidant capacity to human cells. In recent decades, by coupling in silico and experimental methods, several natural products have been characterized to exert antioxidant effects by targeting the KEAP1/NRF2 pathway. In this review article, we analyze several natural products that were investigated experimentally and in silico for their ability to modulate KEAP1/NRF2 by non-covalent and covalent mechanisms. These latter represent the two main sections of this article. For each class of inhibitors, we reviewed their antioxidant effects and potential therapeutic applications, and where possible, we analyzed the structure-activity relationship (SAR). Moreover, the main computational techniques used for the most promising identified compounds are detailed in this survey, providing an updated view on the development of natural products as antioxidant agents.

Dual stimuli-responsive and sustained drug delivery NanoSensoGel formulation for prevention of cisplatin-induced ototoxicity

Cisplatin (CisPt)-induced ototoxicity (CIO) is delineated as a consequence of CisPt-induced intracellular generation of reactive oxygen species (ROS) which can be circumvented by Bucillamine (BUC; an antioxidant drug with sulfhydryl groups) and Diltiazem (DLT, L-type calcium channel blocker). However, its effective accumulation in the Organ of Corti and cell cytoplasm is desired. Therefore, a biocompatible BUC- and DLT-nanoparticles (NPs)-impregnated dual stimuli-responsive formulation (NanoSensoGel) presented here with ROS- and thermo-responsive properties for the sustained and receptive delivery of drugs. The ROS-responsive polypropylene sulfide- methyl polyethylene glycol-2000 (PPS-mPEG2000) polymer was rationally designed, synthesized, and characterized to fabricate BUC- and DLT-loaded PPS-mPEG2000-NPs (BUC- and DLT-NPs). The fabricated BUC- and DLT-NPs showed efficient cellular uptake, intracellular delivery, ROS responsiveness, and cytoprotective effect which was characterized using cellular internalization, intracellular ROS, mitochondrial superoxide, and Caspase 3/7 assays on the House Ear Institute-Organ of Corti-1 (HEI-OC1) cells. The composite NanoSensoGel (i.e., ROS-responsive BUC- and DLT-NPs suspended in the thermo-responsive hydrogel) present in a sol state at room temperature and turned to gel above 33°C, which could be essential for retaining the formulation at the target site for long-term release. The NanoSensoGel showed sustained release of BUC and DLT following Fickian release diffusion kinetics. Overall, a novel NanoSensoGel formulation developed in this study has demonstrated its great potential in delivering therapeutics in the inner ear for prophylactic treatment of CIO, and associated hearing loss.

4-octyl itaconate alleviates cisplatin-induced ferroptosis possibly via activating the NRF2/HO-1 signalling pathway

Ferroptosis, characterized by iron-dependent lipid reactive oxygen species (ROS) accumulation, plays a pivotal role in cisplatin-induced ototoxicity. Existing research has suggested that in cisplatin-mediated damage to auditory cells and hearing loss, ferroptosis is partially implicated. 4-Octyl itaconate (4-OI), derived from itaconic acid, effectively permeates cell membranes, showcasing potent anti-inflammatory as well as antioxidant effects in several disease models. Our study aimed to investigate the effect of 4-OI on cisplatin-induced ferroptosis and the underlying molecular mechanisms. The survival rates of HEI-OC1 cells and mice cochlea hair cells were measured by CCK8 and immunofluorescence, respectively. The auditory brainstem response (ABR) audiometry was used to detect changes in hearing thresholds in mice before and after treatment. Levels of ROS were evaluated by DCFH-DA. Real-time PCR quantified inflammatory cytokines TNF-α, IL-6 and IL-1β. Network Pharmacology and RNA sequencing (RNA-seq) analysis of the potential mechanism of 4-OI resistance to cisplatin-induced ferroptosis. The expressions of ferroptosis-related factors (GPX4, SLC7A11 and PTGS2) and important antioxidant factors (NRF2, HO-1, GCLC and NQO1) were tested by real-time PCR, Western blot and immunofluorescence. Results demonstrated cisplatin-induced significant ROS and inflammatory factor release, reduced NRF2 expression, hindered nuclear translocation and activated ferroptosis. Pretreatment with 4-OI exhibited anti-inflammatory and antioxidant effects, along with resistance to ferroptosis, ultimately mitigating cisplatin-induced cell loss. In the present study, we show that 4-OI inhibits cisplatin-induced ferroptosis possibly through activation of the NRF2/HO-1 signalling pathway, thereby exerting a protective effect against cisplatin-induced damage to auditory cells, and providing a new therapeutic strategy for cisplatin-induced hearing loss.

Identification of common stria vascularis cellular alteration in sensorineural hearing loss based on ScRNA-seq

BACKGROUND

The stria vascularis (SV), located in the lateral wall of the cochlea, maintains cochlear fluid homeostasis and mechanoelectrical transduction (MET) activity required for sound wave conduction. The pathogenesis of a number of human inheritable deafness syndromes, age related hearing loss, drug-induced ototoxicity and noise-induced hearing loss results from the morphological changes and functional impairments in the development of the SV. In this study, we investigate the implications of intercellular communication within the SV in the pathogenesis of sensorineural hearing loss (SNHL). We aim to identify commonly regulated signaling pathways using publicly available single-cell transcriptomic sequencing (scRNA-seq) datasets.

METHODS

We analyzed scRNA-seq data, which was derived from studying the cochlear SV in mice with SNHL compared to normal adult mice. After quality control and filtering, we obtained the major cellular components of the mouse cochlear SV and integrated the data. Using Seurat's FindAllMarkers and FindMarkers packages, we searched for novel conservative genes and differential genes. We employed KEGG and GSEA to identify molecular pathways that are commonly altered among different types of SNHL. We utilized pySCENIC to discover new specific regulatory factors in SV subpopulation cells. With the help of CellChat, we identified changes in subpopulation cells showing similar trends across different SNHL types and their alterations in intercellular communication pathways.

RESULTS

Through the analysis of the integrated data, we discovered new conserved genes to SV specific cells and identified common downregulated pathways in three types of SNHL. The enriched genes for these pathways showing similar trends are primarily associated with the Electron Transport Chain, related to mitochondrial energy metabolism. Using the CellChat package, we further found that there are shared pathways in the incoming signaling of specific intermediate cells in SNHL, and these pathways have common upstream regulatory transcription factor of Nfe2l2. Combining the results from pySCENIC and CellChat, we predicted the transcription factor Nfe2l2 as an upstream regulatory factor for multiple shared cellular pathways in IC. Additionally, it serves as an upstream factor for several genes within the Electron Transport Chain.

CONCLUSION

Our bioinformatics analysis has revealed that downregulation of the mitochondrial electron transport chain have been observed in various conditions of SNHL. E2f1, Esrrb, Runx1, Yy1, and Gata2 could serve as novel important common TFs regulating the electron transport chain. Adm has emerged as a potential new marker gene for intermediate cells, while Itgb5 and Tesc show promise as potential new marker genes for marginal cells in the SV. These findings offer a new perspective on SV lesions in SNHL and provide additional theoretical evidence for the same drug treatment and prevention of different pathologies of SNHL.

Identification and experimental validation of ferroptosis-related gene lactotransferrin in age-related hearing loss

Objective

To reveal the relationship between ARHL and ferroptosis and screen ferroptosis-related genes (FRGs) in ARHL.

Methods

Bioinformatics were used to analyze the hub genes and molecular mechanism of ferroptosis in the aging cochleae. Senescence β-galactosidase staining, iron content detection, and micro malondialdehyde (MDA) assay kits were used to measure β-galactosidase activity, and expression of Fe2+ and MDA, respectively. Fluorescence microscope was used for immunofluorescence assay of hub genes. Western blot was used to verify the expression of hub genes in HEI-OC1 cells, cochlear explants, and cochleae of C57BL/6J mice. Data were expressed as mean ± SD of at least three independent experiments.

Results

The analysis of bioinformatics confirmed that lactotransferrin (LTF) is the hub gene and CEBPA-miR-130b-LTF network is the molecular mechanism for cochlear ferroptosis. Compared with the control group, the experiments proved that the indicators of ferroptosis, including Fe2+, MDA, and LTF were differentially expressed in aging HEI-OC1 cells, aging cochlear explants, and aging cochleae.

Conclusion

These results demonstrate that ferroptosis plays an important role in ARHL, and LTF is a potential therapeutic target for ARHL via regulating cochlear ferroptosis.

Drug screening identifies aldose reductase as a novel target for treating cisplatin-induced hearing loss

Cisplatin is a frequently used chemotherapeutic medicine for cancer treatment. Permanent hearing loss is one of the most serious side effects of cisplatin, but there are few FDA-approved medicines to prevent it. We applied high-through screening and target fishing and identified aldose reductase, a key enzyme of the polyol pathway, as a novel target for treating cisplatin ototoxicity. Cisplatin treatment significantly increased the expression level and enzyme activity of aldose reductase in the cochlear sensory epithelium. Genetic knockdown or pharmacological inhibition of aldose reductase showed a significant protective effect on cochlear hair cells. Cisplatin-induced overactivation of aldose reductase led to the decrease of NADPH/NADP+ and GSH/GSSG ratios, as well as the increase of oxidative stress, and contributed to hair cell death. Results of target prediction, molecular docking, and enzyme activity detection further identified that Tiliroside was an effective inhibitor of aldose reductase. Tiliroside was proven to inhibit the enzymatic activity of aldose reductase via competitively interfering with the substrate-binding region. Both Tiliroside and another clinically approved aldose reductase inhibitor, Epalrestat, inhibited cisplatin-induced oxidative stress and subsequent cell death and thus protected hearing function. These findings discovered the role of aldose reductase in the pathogenesis of cisplatin-induced deafness and identified aldose reductase as a new target for the prevention and treatment of hearing loss.

Taxifolin-mediated Nrf2 activation ameliorates oxidative stress and apoptosis for the treatment of glucocorticoid-induced osteonecrosis of the femoral head

Glucocorticoid-induced osteonecrosis of the femoral head (GIONFH) is the main complication secondary to long-term or excessive use of glucocorticoids (GCs). Taxifolin (TAX) is a natural antioxidant with various pharmacological effects, such as antioxidative stress and antiapoptotic properties. The purpose of this study was to explore whether TAX could regulate oxidative stress and apoptosis in GIONFH by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. We conducted qRT-PCR, Western blotting, TUNEL assays, flow cytometry, and other experiments in vitro. Microcomputed tomography analysis, hematoxylin-eosin staining, and immunohistochemical staining were performed to determine the therapeutic effect of TAX in vivo. TAX mitigated the overexpression of ROS and NOX gene expression induced by DEX, effectively reducing oxidative stress. Additionally, TAX could alleviate DEX-induced osteoblast apoptosis, as evidenced by qRT-PCR, Western blotting, and other experimental techniques. Our in vivo studies further demonstrated that TAX mitigates the progression of GIONFH in rats by combating oxidative stress and apoptosis. Mechanistic exploration revealed that TAX thwarts the progression of GIONFH through the activation of the Nrf2 pathway. Overall, our research herein reports that TAX-mediated Nrf2 activation ameliorates oxidative stress and apoptosis for the treatment of GIONFH.

Lysophosphatidic acid exerts protective effects on HEI-OC1 cells against cytotoxicity of cisplatin by decreasing apoptosis, excessive autophagy, and accumulation of ROS

Lysophosphatidic acid (LPA) is an active phospholipid signaling molecule that binds to six specific G protein-coupled receptors (LPA1-6) on the cell surface and exerts a variety of biological functions, including cell migration and proliferation, morphological changes, and anti-apoptosis. The earliest study from our group demonstrated that LPA treatment could restore cochlear F-actin depolymerization induced by noise exposure, reduce hair cell death, and thus protect hearing. However, whether LPA could protect against cisplatin-induced ototoxicity and which receptors play the major role remain unclear. To this end, we integrated the HEI-OC1 mouse cochlear hair cell line and zebrafish model, and found that cisplatin exposure induced a large amount of reactive oxygen species accumulation in HEI-OC1 cells, accompanied by mitochondrial damage, leading to apoptosis and autophagy. LPA treatment significantly attenuated autophagy and apoptosis in HEI-OC1 cells after cisplatin exposure. Further investigation revealed that all LPA receptors except LPA3 were expressed in HEI-OC1 cells, and the mRNA expression level of LPA1 receptor was significantly higher than that of other receptors. When LPA1 receptor was silenced, the protective effect of LPA was reduced and the proportion of apoptosis cells was increased, indicating that LPA-LPA1 plays an important role in protecting HEI-OC1 cells from cisplatin-induced apoptosis. In addition, the behavioral trajectory and in vivo fluorescence imaging results showed that cisplatin exposure caused zebrafish to move more actively, and the movement speed and distance were higher than those of the control and LPA groups, while LPA treatment reduced the movement behavior. Cisplatin caused hair cell death and loss in zebrafish lateral line, and LPA treatment significantly protected against hair cell death and loss. LPA has a protective effect on hair cells in vitro and in vivo against the cytotoxicity of cisplatin, and its mechanism may be related to reducing apoptosis, excessive autophagy and ROS accumulation.

FAM134B-induced endoplasmic reticulum (ER)-phagy exacerbates cisplatin-insulted hair cell apoptosis ：Possible relation to excessive ER stress

AIMS

FAM134B, the initial endoplasmic reticulum (ER)-phagy receptor identified, facilitates ER-phagy during ER stress. The malfunction of FAM134B has been demonstrated to have a crucial role in the pathological mechanisms of diverse human ailments. However, the role of FAM134B-mediated ER-phagy in ototoxicity, particularly in cisplatin-induced ototoxicity, remains unclear. The present study endeavors to investigate whether FAM134B is expressed in House Ear Institute-Organ of Corti 1 (HEI-OC1) and C57BL/6 murine cochlear hair cells (HCs), and to explore its potential function in cisplatin-mediated ototoxicity, with the aim of discovering new insights that can mitigate or forestall the irreversible adverse effect of cisplatin.

METHODS

Immunofluorescence (IF) staining was used to test the expression pattern of FAM134B, levels of C/EBP-homologous protein (CHOP), autophagy, and co-localization ratio of lysosomes and ER. Western blotting was employed to measure changes in expression levels of FAM134B, LC3B, ER stress-related proteins, LAMP1 and apoptotic mediators. Cell apoptosis was examined using transferase dUTP nick end labeling (TUNEL) assay and flow cytometry.

RESULTS

In the present investigation, it was observed that FAM134B exhibited a diffuse expression pattern in the cytoplasm and nuclei of control HEI-OC1 cells. Following cisplatin administration, FAM134B was found to accumulate and form distinct dots around the nuclei, concomitant with increased levels of ER-phagy, ER stress, unfolded protein response (UPR), and cell apoptosis. Additionally, knockdown of FAM134B resulted in reduced ER-phagy, mitigated ER stress and UPR, and decreased apoptotic activity in HEI-OC1 cells following cisplatin exposure.

CONCLUSIONS

Collectively, the findings of this study demonstrate that FAM134B-mediated ER-phagy enhances the susceptibility of HCs to ER stress and apoptosis in response to cisplatin-induced stress. This suggests a sequential progression of ER-phagy, ER stress and apoptosis following cisplatin stimulus, and implies the potential therapeutic benefit of inhibiting of FAM134B-mediated ER-phagy in the prevention of cisplatin-related ototoxicity.

Apelin-13 protects against cisplatin-induced ototoxicity by inhibiting apoptosis and regulating STAT1 and STAT3

The ototoxic side effect of cisplatin is a main cause of sensorineural hearing loss. This side effect limits the clinical application of cisplatin and affects patients' quality of life. This study was designed to investigate the effect of apelin-13 on cisplatin-induced C57BL/6 mice hearing loss model and explore the potential underlying molecular mechanisms. Mice were intraperitoneally injected with 100 μg/kg apelin-13 2 h before 3 mg/kg cisplatin injection for 7 consecutive days. Cochlear explants cultured in vitro were pretreated with 10 nM apelin-13 2 h prior to 30 μM cisplatin treatment for another 24 h. Hearing test and morphology results showed that apelin-13 attenuated cisplatin-induced mice hearing loss and protected cochlear hair cells and spiral ganglion neurons from damage. In vivo and in vitro experimental results showed that apelin-3 reduced cisplatin-induced apoptosis of hair cells and spiral ganglion neurons. In addition, apelin-3 preserved mitochondrial membrane potential and inhibited ROS production in cultured cochlear explants. Mechanistic studies showed that apelin-3 decreased cisplatin-induced cleaved caspase 3 expression but increased Bcl-2; inhibited the expression of pro-inflammatory factors TNF-a and IL-6; and increased STAT1 phosphorylation but decreased STAT3 phosphorylation. In conclusion, our results indicate that apelin-13 could be a potential otoprotective agent to prevent cisplatin-induced ototoxicity by inhibiting apoptosis, ROS production, TNF-α and IL-6 expression, and regulating phosphorylation of STAT1 and STAT3 transcription factors.

Pharmacological activation of the Nrf2 pathway by Taxifolin remodels articular cartilage microenvironment for the therapy of Osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a widely prevalent degenerative disease marked by extracellular matrix (ECM) degradation, inflammation, and apoptosis. Taxifolin (TAX) is a natural antioxidant possessing various pharmacological benefits, such as combating inflammation, oxidative stress, apoptosis, and serves as a potential chemopreventive agent by regulating genes through an antioxidant response element (ARE)-dependent mechanism. Currently, no studies have investigated the therapeutic impact and precise mechanism of TAX on OA.

PURPOSE

The aim of this study is to examine the potential role and mechanism of TAX in reshaping the cartilage microenvironment, thereby offering a stronger theoretical foundation for pharmacologically activating the Nrf2 pathway to manage OA.

STUDY DESIGN AND METHODS

The pharmacological effects of TAX were examined in chondrocytes through in vitro studies and in a destabilization of the medial meniscus (DMM) rat model for in vivo analysis.

RESULTS

TAX suppresses IL-1β triggered secretion of inflammatory agents, chondrocyte apoptosis, and ECM degradation, contributing to the remodeling of the cartilage microenvironment. In vivo experiment results demonstrated that TAX counteracted cartilage degeneration induced by DMM in rats. Mechanistic investigations revealed that TAX hinders OA development by reducing NF-κB activation and ROS production through the activation of the Nrf2/HO-1 axis.

CONCLUSION

TAX reshapes the articular cartilage microenvironment by suppressing inflammation, mitigating apoptosis, and decreasing ECM degradation through the activation of the Nrf2 pathway. As a result, pharmacological activation of the Nrf2 pathway by TAX holds potential clinical significance in remodeling the joint microenvironment for OA treatment.

Effects of natural products on cisplatin ototoxicity and chemotherapeutic efficacy

INTRODUCTION

Cisplatin is a very effective chemotherapeutic agent against a variety of solid tumors. Unfortunately, cisplatin causes permanent sensorineural hearing loss in at least two-thirds of patients treated. There are no FDA approved drugs to prevent this serious side effect.

AREAS COVERED

This paper reviews various natural products that ameliorate cisplatin ototoxicity. These compounds are strong antioxidants and anti-inflammatory agents. This review includes mostly preclinical studies but also discusses a few small clinical trials with natural products to minimize hearing loss from cisplatin chemotherapy in patients. The interactions of natural products with cisplatin in tumor-bearing animal models are highlighted. A number of natural products did not interfere with cisplatin anti-tumor efficacy and some agents actually potentiated cisplatin anti-tumor activity.

EXPERT OPINION

There are a number of natural products or their derivatives that show excellent protection against cisplatin ototoxicity in preclinical studies. There is a need to insure uniform standards for purity of drugs derived from natural sources and to ensure adequate pharmacokinetics and safety of these products. Natural products that protect against cisplatin ototoxicity and augment cisplatin's anti-tumor effects in multiple studies of tumor-bearing animals are most promising for advancement to clinical trials. The most promising natural products include honokiol, sulforaphane, and thymoquinone.

Cisplatin ototoxicity mechanism and antagonistic intervention strategy: a scope review

Cisplatin is a first-line chemotherapeutic agent in the treatment of malignant tumors with remarkable clinical effects and low cost. However, the ototoxicity and neurotoxicity of cisplatin greatly limit its clinical application. This article reviews the possible pathways and molecular mechanisms of cisplatin trafficking from peripheral blood into the inner ear, the toxic response of cisplatin to inner ear cells, as well as the cascade reactions leading to cell death. Moreover, this article highlights the latest research progress in cisplatin resistance mechanism and cisplatin ototoxicity. Two effective protective mechanisms, anti-apoptosis and mitophagy activation, and their interaction in the inner ear are discussed. Additionally, the current clinical preventive measures and novel therapeutic agents for cisplatin ototoxicity are described. Finally, this article also forecasts the prospect of possible drug targets for mitigating cisplatin-induced ototoxicity. These include the use of antioxidants, inhibitors of transporter proteins, inhibitors of cellular pathways, combination drug delivery methods, and other mechanisms that have shown promise in preclinical studies. Further research is needed to evaluate the efficacy and safety of these approaches.

5,7-Dihydroxy-4-methylcoumarin modulates the JNK/FoxO1 signaling pathway to attenuate cisplatin-induced ototoxicity by suppressing oxidative stress and apoptosis in vitro

5,7-Dihydroxy-4-methylcoumarin (D4M) is attributed to free radical scavenging effects, with wide application for anti-oxidation. This work aimed to assess D4M's impact on cisplatin-induced ototoxicity. The cell viability was estimated with CCK-8 assay. Apoptosis was detected by the Annexin V-FITC and PI assay. The reactive oxygen species (ROS) level was determined by MitoSOX-Red and CellROX-Green probes. Mitochondrial membrane potential was analyzed with TMRM staining. Immunofluorescence was utilized for hair cells and spiral ganglion neuron detection. Apoptosis-associated proteins were assessed by cleaved caspase-3 and TUNEL staining. These results showed that D4M pretreatment protected hair cells from cisplatin-induced damage, increased cell viability, and decreased apoptosis in House Ear Institute-Organ of Corti1 (HEI-OC1) cells and neonatal mouse cochlear explants. D4M significantly inhibited cisplatin-induced mitochondrial apoptosis and reduced ROS accumulation. In addition, the protective effect of D4M on cisplatin-induced ototoxicity was also confirmed in cochlear hair cells and spiral ganglion neurons in neonatal mice. Mechanistic studies showed that D4M markedly downregulated p-JNK and elevated the expression ratio of p-FoxO1/FoxO1, thereby reducing cisplatin-induced caspase-dependent apoptosis. Meanwhile, D4M-related protection of HEI-OC1 cells was significantly blunted by JNK signaling induction with anisomycin. This study supports the possibility that D4M may be used as a new compound to prevent cisplatin-related hearing loss.

Cisplatin-induced ototoxicity: From signaling network to therapeutic targets

Administration of cisplatin, a common chemotherapeutic drug, has an inevitable side effect of sensorineural hearing loss. The main etiologies are stria vascularis injury, spiral ganglion degeneration, and hair cell death. Over several decades, the research scope of cisplatin-induced ototoxicity has expanded with the discovery of the molecular mechanism mediating inner ear cell death, highlighting the roles of reactive oxygen species and transport channels for cisplatin uptake into inner ear cells. Upon entering hair cells, cisplatin disrupts organelle metabolism, induces oxidative stress, and targets DNA to cause intracellular damage. Recent studies have also reported the role of inflammation in cisplatin-induced ototoxicity. In this article, we preform a narrative review of the latest reported molecular mechanisms of cisplatin-induced ototoxicity, from extracellular to intracellular. We build up a signaling network starting with cisplatin entering into the inner ear through the blood labyrinth barrier, disrupting cochlear endolymph homeostasis, and activating inflammatory responses of the outer hair cells. After entering the hair cells, cisplatin causes hair cell death via DNA damage, redox system imbalance, and mitochondrial and endoplasmic reticulum dysfunction, culminating in programmed cell death including apoptosis, necroptosis, autophagic death, pyroptosis, and ferroptosis. Based on the mentioned mechanisms, prominent therapeutic targets, such as channel-blocking drugs of cisplatin transporter, construction of cisplatin structural analogues, anti-inflammatory drugs, antioxidants, cell death inhibitors, and others, were collated. Considering the recent research efforts, we have analyzed the feasibility of the aforementioned therapeutic strategies and proposed our otoprotective approaches to overcome cisplatin-induced ototoxicity.

SIRT3-mediated deacetylation protects inner hair cell synapses in a H2O2-induced oxidative stress model in vitro

Oxidative stress is considered a driving event in the damage to inner hair cell (IHC) synapses. Mitochondrial deacetylase Sirtuin 3 (SIRT3) is an important regulator of reactive oxygen species (ROS) production. However, the effect of SIRT3 on IHC synapses remains elusive. In this study, we treated cochlear basilar membrane (CBM) with hydrogen peroxide (H₂O₂) to establish an oxidative stress model in vitro. The H₂O₂-induced CBM exhibited decreased the number of IHC synapses with low levels of ATP and mitochondrial membrane potential. Additionally, H₂O₂-incuded CBM showed markedly reduced levels of forkhead box protein O 3a (FOXO3a), superoxide dismutase 2 (SOD2), and isocitrate dehydrogenase 2 (IDH2), thereby increasing ROS generation. SIRT3 overexpression via administrating nicotinamide riboside in the H₂O₂-induced CBM protected IHC synapses against oxidative stress and inhibited hair cell apoptosis. We further demonstrated that SIRT3 overexpression led to upregulation of IDH2, and hypoacetylation of several proteins, such as FOXO3a and SOD2, which in turn reduced the levels of ROS and improved mitochondrial function. Collectively, these findings reveal that SIRT3 may be a potential therapeutic approach for damaged IHC synapses induced by oxidative stress.

Health benefits of astaxanthin against age-related diseases of multiple organs: A comprehensive review

Age-related diseases are associated with increased morbidity in the past few decades and the cost associated with the treatment of these age-related diseases exerts a substantial impact on social and health care expenditure. Anti-aging strategies aim to mitigate, delay and reverse aging-associated diseases, thereby improving quality of life and reducing the burden of age-related pathologies. The natural dietary antioxidant supplementation offers substantial pharmacological and therapeutic effects against various disease conditions. Astaxanthin is one such natural carotenoid with superior antioxidant activity than other carotenoids, as well as well as vitamins C and E, and additionally, it is known to exhibit a plethora of pharmacological effects. The present review summarizes the protective molecular mechanisms of actions of astaxanthin on age-related diseases of multiple organs such as Neurodegenerative diseases [Alzheimer's disease (AD), Parkinson's disease (PD), Stroke, Multiple Sclerosis (MS), Amyotrophic lateral sclerosis (ALS), and Status Epilepticus (SE)], Bone Related Diseases [Osteoarthritis (OA) and Osteoporosis], Cancers [Colon cancer, Prostate cancer, Breast cancer, and Lung Cancer], Cardiovascular disorders [Hypertension, Atherosclerosis and Myocardial infarction (MI)], Diabetes associated complications [Diabetic nephropathy (DN), Diabetic neuropathy, and Diabetic retinopathy (DR)], Eye disorders [Age related macular degeneration (AMD), Dry eye disease (DED), Cataract and Uveitis], Gastric Disorders [Gastritis, Colitis, and Functional dyspepsia], Kidney Disorders [Nephrolithiasis, Renal fibrosis, Renal Ischemia reperfusion (RIR), Acute kidney injury (AKI), and hyperuricemia], Liver Diseases [Nonalcoholic fatty liver disease (NAFLD), Alcoholic Liver Disease (AFLD), Liver fibrosis, and Hepatic Ischemia-Reperfusion (IR) Injury], Pulmonary Disorders [Pulmonary Fibrosis, Acute Lung injury (ALI), and Chronic obstructive pulmonary disease (COPD)], Muscle disorders (skeletal muscle atrophy), Skin diseases [Atopic dermatitis (ATD), Skin Photoaging, and Wound healing]. We have also briefly discussed astaxanthin's protective effects on reproductive health.