Oxidative Stress and Inflammation Caused by Cisplatin Ototoxicity

FDA-Approved Tedizolid Phosphate Prevents Cisplatin-Induced Hearing Loss Without Decreasing Its Anti-tumor Effect

PURPOSE

Cisplatin is a low-cost clinical anti-tumor drug widely used to treat solid tumors. However, its use could damage cochlear hair cells, leading to irreversible hearing loss. Currently, there appears one drug approved in clinic only used for reducing ototoxicity associated with cisplatin in pediatric patients, which needs to further explore other candidate drugs.

METHODS

Here, by screening 1967 FDA-approved drugs to protect cochlear hair cell line (HEI-OC1) from cisplatin damage, we found that Tedizolid Phosphate (Ted), a drug indicated for the treatment of acute infections, had the best protective effect. Further, we evaluated the protective effect of Ted against ototoxicity in mouse cochlear explants, zebrafish, and adult mice. The mechanism of action of Ted was further explored using RNA sequencing analysis and verified. Meanwhile, we also observed the effect of Ted on the anti-tumor effect of cisplatin.

RESULTS

Ted had a strong protective effect on hair cell (HC) loss induced by cisplatin in zebrafish and mouse cochlear explants. In addition, when administered systemically, it protected mice from cisplatin-induced hearing loss. Moreover, antitumor studies showed that Ted had no effect on the antitumor activity of cisplatin both in vitro and in vivo. RNA sequencing analysis showed that the otoprotective effect of Ted was mainly achieved by inhibiting phosphorylation of ERK. Consistently, ERK activator aggravated the damage of cisplatin to HCs.

CONCLUSION

Collectively, these results showed that FDA-approved Ted protected HCs from cisplatin-induced HC loss by inhibiting ERK phosphorylation, indicating its potential as a candidate for preventing cisplatin ototoxicity in clinical settings.

Oseltamivir (Tamiflu), a Commonly Prescribed Antiviral Drug, Mitigates Hearing Loss in Mice

Hearing loss affects up to 10% of all people worldwide, but currently there is only one FDA-approved drug for its prevention in a subgroup of cisplatin-treated pediatric patients. Here, we performed an unbiased screen of 1,300 FDA-approved drugs for protection against cisplatin-induced cell death in an inner ear cell line, and identified oseltamivir phosphate (brand name Tamiflu), a common influenza antiviral drug, as a top candidate. Oseltamivir phosphate was found to be otoprotective by oral delivery in multiple established cisplatin and noise exposure mouse models. The drug conferred permanent hearing protection of 15-25 dB SPL for both female and male mice. Oseltamivir treatment reduced in mice outer hair cells death after cisplatin treatment and mitigated cochlear synaptopathy after noise exposure. A potential binding protein, ERK1/2, associated with inflammation, was shown to be activated with cisplatin treatment and reduced by oseltamivir cotreatment in cochlear explants. Importantly, the number of infiltrating immune cells to the cochleae in mice post noise exposure, were significantly reduced with oseltamivir treatment, suggesting an anti-inflammatory mechanism of action. Our results support oseltamivir, a widespread drug for influenza with low side effects, as a promising otoprotective therapeutic candidate in both cisplatin chemotherapy and traumatic noise exposure.

KSR1 Knockout Mouse Model Demonstrates MAPK Pathway's Key Role in Cisplatin- and Noise-induced Hearing Loss

Hearing loss is a major disability in everyday life and therapeutic interventions to protect hearing would benefit a large portion of the world population. Here we found that mice devoid of the protein kinase suppressor of RAS 1 (KSR1) in their tissues (germline KO mice) exhibit resistance to both cisplatin- and noise-induced permanent hearing loss compared with their wild-type KSR1 littermates. KSR1 is a scaffold protein that brings in proximity the mitogen-activated protein kinase (MAPK) proteins BRAF, MEK1/2 and ERK1/2 and assists in their activation through a phosphorylation cascade induced by both cisplatin and noise insults in the cochlear cells. KSR1, BRAF, MEK1/2, and ERK1/2 are all ubiquitously expressed in the cochlea. Deleting the KSR1 protein tempered down the MAPK phosphorylation cascade in the cochlear cells following both cisplatin and noise insults and conferred hearing protection of up to 30 dB SPL in three tested frequencies in male and female mice. Treatment with dabrafenib, an FDA-approved oral BRAF inhibitor, protected male and female KSR1 wild-type mice from both cisplatin- and noise-induced hearing loss. Dabrafenib treatment did not enhance the protection of KO KSR1 mice, providing evidence dabrafenib works primarily through the MAPK pathway. Thus, either elimination of the KSR1 gene expression or drug inhibition of the MAPK cellular pathway in mice resulted in profound protection from both cisplatin- and noise-induced hearing loss. Inhibition of the MAPK pathway, a cellular pathway that responds to damage in the cochlear cells, can prove a valuable strategy to protect and treat hearing loss.

Role of Oxidative Stress in Sensorineural Hearing Loss

Hearing is essential for communication, and its loss can cause a serious disruption to one's social life. Hearing loss is also recognized as a major risk factor for dementia; therefore, addressing hearing loss is a pressing global issue. Sensorineural hearing loss, the predominant type of hearing loss, is mainly due to damage to the inner ear along with a variety of pathologies including ischemia, noise, trauma, aging, and ototoxic drugs. In addition to genetic factors, oxidative stress has been identified as a common mechanism underlying several cochlear pathologies. The cochlea, which plays a major role in auditory function, requires high-energy metabolism and is, therefore, highly susceptible to oxidative stress, particularly in the mitochondria. Based on these pathological findings, the potential of antioxidants for the treatment of hearing loss has been demonstrated in several animal studies. However, results from human studies are insufficient, and future clinical trials are required. This review discusses the relationship between sensorineural hearing loss and reactive oxidative species (ROS), with particular emphasis on age-related hearing loss, noise-induced hearing loss, and ischemia-reperfusion injury. Based on these mechanisms, the current status and future perspectives of ROS-targeted therapy for sensorineural hearing loss are described.

Nobiletin alleviates cisplatin-induced ototoxicity via activating autophagy and inhibiting NRF2/GPX4-mediated ferroptosis

Nobiletin, a citrus polymethoxy flavonoid with antiapoptotic and antioxidative properties, could safeguard against cisplatin-induced nephrotoxicity and neurotoxicity. Cisplatin, as the pioneer of anti-cancer drug, the severe ototoxicity limits its clinical applications, while the effect of nobiletin on cisplatin-induced ototoxicity has not been identified. The current study investigated the alleviating effect of nobiletin on cisplatin-induced ototoxicity and the underlying mechanisms. Apoptosis and ROS formation were evaluated using the CCK-8 assay, Western blotting, and immunofluorescence, indicating that nobiletin attenuated cisplatin-induced apoptosis and oxidative stress. LC3B and SQSTM1/p62 were determined by Western blotting, qPCR, and immunofluorescence, indicating that nobiletin significantly activated autophagy. Nobiletin promoted the nuclear translocation of NRF2 and the transcription of its target genes, including Hmox1, Nqo1, and ferroptosis markers (Gpx4, Slc7a11, Fth, and Ftl), thereby inhibiting ferroptosis. Furthermore, RNA sequencing analysis verified that autophagy, ferroptosis, and the NRF2 signaling pathway served as crucial points for the protection of nobiletin against ototoxicity caused by cisplatin. Collectively, these results indicated, for the first time, that nobiletin alleviated cisplatin-elicited ototoxicity through suppressing apoptosis and oxidative stress, which were attributed to the activation of autophagy and the inhibition of NRF2/GPX4-mediated ferroptosis. Our study suggested that nobiletin could be a prospective agent for preventing cisplatin-induced hearing loss.

Blood-Labyrinth Barrier in Health and Diseases: Effect of Hormetic Nutrients

Significance: The stria vascularis, located in the inner ear, consists of three layers, one of which is the blood-labyrinth barrier (BLB). It is formed by endothelial cells, sealed together to prevent the passage of toxic substances from the blood to the inner ear, by pericytes and perivascular-resident macrophage-like melanocyte. Recent Advances: There are various causes that lead to hearing loss, and among these are noise-induced and autoimmune hearing loss, ear disorders related to ototoxic medication, Ménière's disease, and age-related hearing loss. For all of these, major therapeutic interventions include drug-loaded nanoparticles, via intratympanic or intracochlear delivery. Critical Issues: Since many pathologies associated with hearing loss are characterized by a weakening of the BLB, in this review, the molecular mechanisms underlying the response to damage of BLB cellular components have been discussed. In addition, insight into the role of hormetic nutrients against hearing loss pathology is proposed. Future Directions: BLB cellular components of neurovascular cochlear unit play important physiological roles, owing to their impermeable function against all ototoxic substances that can induce damage. Studies are needed to investigate the cross talk occurring between these cellular components to exploit their possible role as novel targets for therapeutic interventions that may unravel future path based on the use of hormetic nutrients. Antioxid. Redox Signal. 40, 542-563.

Anticancer therapy-induced adverse drug reactions in children and preventive and control measures

In recent years, considerable achievements have been made in pediatric oncology with the innovation and development of antitumor drugs. However, compared to adults, children as a special group have not yet matured fully in terms of liver and kidney function. Moreover, pediatric patients are prone to more adverse drug reactions (ADRs) from the accumulation of antineoplastic drugs due to their smaller body size and larger body surface area. Chemotherapy-related ADRs have become a non-negligible factor that affects cancer remission. To date, studies on ADRs in pediatric cancer patients have emerged internationally, but few systematic summaries are available. Here, we reviewed the various systemic ADRs associated with antitumor drugs in children and adolescent patients, as well as the advances in strategies to cope with ADRs, which consisted of neurotoxicity, hematological toxicity, cardiotoxicity, ADRs of the respiratory system and gastrointestinal system and urinary system, ADRs of the skin and its adnexa, allergic reactions, and other ADRs. For clinicians and researchers, understanding the causes, symptoms, and coping strategies for ADRs caused by anticancer treatments will undoubtedly benefit more children.

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

Cinchonine and cinchonidine alleviate cisplatin-induced ototoxicity by regulating PI3K-AKT signaling

AIM

Cinchonine (CN) and its isomer cinchonidine (CD), two of the common cinchona alkaloids, are wildly used as antimalarial drugs. However, the effects of CN and CD on the auditory system are unknown.

METHODS

Molecular docking and molecular dynamics (MD) simulation were used for predicting effective drugs. The CCK-8 assay was conducted for assessing cell viability in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells. MitoSox Red staining revealed reactive oxygen species (ROS) amounts. TMRM staining was used to assess the mitochondrial membrane potential (ΔΨm). Immunofluorescence staining of myosin 7a was used to examine hair cells (HCs) in cisplatin-treated neonatal mouse cochlear explants, while TUJ-1 immunostaining was used for the detection of spiral ganglion neurons (SGNs). Cleaved caspase-3 and TUNEL immunostaining were utilized for apoptosis assessment. Immunoblot was carried out to detect PI3K-AKT signaling effectors.

RESULTS

Pretreatment with CN or CD significantly increased cell viability and reduced mitochondrial dysfunction and ROS accumulation in cisplatin-treated HEI-OC1 cells. Immunofluorescent staining of cochlear explants showed that CN and CD attenuated cisplatin-induced damage to SGNs and HCs. Immunoblot revealed that CN and CD downregulated the expression of cleaved caspase-3 and activated PI3K-AKT signaling in cisplatin-injured HEI-OC1 cells.

CONCLUSION

CD and CN can reduce ototoxicity caused by cisplatin and might help treat cisplatin-associated hearing loss.

Effect of N-Acetylcysteine on Cisplatin Toxicity: A Review of the Literature

N-acetylcysteine (NAC) is a membrane-permeable cysteine precursor capable of enhancing the intracellular cysteine pool, enhancing cellular glutathione (GSH) synthesis, and thus potentiating the endogenous antioxidant mechanism. Late administration of NAC after cisplatin has been shown in different in vivo studies to reduce the side effects caused by various toxicities at different levels without affecting the antitumor efficacy of platinum, improving total and enzymatic antioxidant capacity and decreasing oxidative stress markers. These characteristics provide NAC with a rationale as a potentially effective chemo protectant in cisplatin-based therapeutic cycles. NAC represents a potential candidate as a chemoprotective agent to decrease toxicities secondary to cisplatin treatment. It suggests that it could be used in clinical trials, whereby the effective dose, timing, and route should be adjusted to optimize chemoprotection. This review provides an overview of the effect of NAC on cisplatin toxicity, a drug widely used in the clinic in adults and children.

GelMA/PEDOT:PSS Composite Conductive Hydrogel-Based Generation and Protection of Cochlear Hair Cells through Multiple Signaling Pathways

Recent advances in cochlear implantology are exemplified by novel functional strategies such as bimodal electroacoustic stimulation, in which the patient has intact low-frequency hearing and profound high-frequency hearing pre-operatively. Therefore, the synergistic restoration of dysfunctional cochlear hair cells and the protection of hair cells from ototoxic insults have become a persistent target pursued for this hybrid system. In this study, we developed a composite GelMA/PEDOT:PSS conductive hydrogel that is suitable as a coating for the cochlear implant electrode for the potential local delivery of otoregenerative and otoprotective drugs. Various material characterization methods (e.g., 1H NMR spectroscopy, FT-IR, EIS, and SEM), experimental models (e.g., murine cochlear organoid and aminoglycoside-induced ototoxic HEI-OC1 cellular model), and biological analyses (e.g., confocal laser scanning microscopy, real time qPCR, flow cytometry, and bioinformatic sequencing) were used. The results demonstrated decent material properties of the hydrogel, such as mechanical (e.g., high tensile stress and Young's modulus), electrochemical (e.g., low impedance and high conductivity), biocompatibility (e.g., satisfactory cochlear cell interaction and free of systemic toxicity), and biosafety (e.g., minimal hemolysis and cell death) features. In addition, the CDR medicinal cocktail sustainably released by the hydrogel not only promoted the expansion of the cochlear stem cells but also boosted the trans-differentiation from cochlear supporting cells into hair cells. Furthermore, hydrogel-based drug delivery protected the hair cells from oxidative stress and various forms of programmed cell death (e.g., apoptosis and ferroptosis). Finally, using large-scale sequencing, we enriched a complex network of signaling pathways that are potentially downstream to various metabolic processes and abundant metabolites. In conclusion, we present a conductive hydrogel-based local delivery of bifunctional drug cocktails, thereby serving as a potential solution to intracochlear therapy of bimodal auditory rehabilitation and diseases beyond.

Inhibition of the HMGB1/RAGE axis protects against cisplatin-induced ototoxicity via suppression of inflammation and oxidative stress

As an anti-tumor drug widely used in the clinic, cisplatin is limited by its ototoxic side effects associated with various factors, including inflammatory responses. Receptor for Advanced Glycation Endproducts (RAGE) recognizes damage-associated molecular patterns (DAMPs) and promotes stress and inflammation. This study intended to determine the potential behavior of the HMGB1/RAGE axis after cisplatin injury and whether it has a protective effect after inhibiting this pathway. We used FPS-ZM1, a RAGE inhibitor, to modulate the axis of HMGB1/RAGE in neonatal mouse cochlear explants and C57BL/6 mice in vivo. Apoptosis was identified by Annexin V-FITC/PI assay, Cleaved Caspase-3, and TUNEL staining. Reactive oxygen species (ROS) level was assessed by MitoSOX Red and CellROX Green assay. The expression of proteins associated with the HMGB1/RAGE axis and apoptosis was observed by western blotting. The expression of inflammatory cytokines was evaluated by qPCR. The protective effect of HMGB1/RAGE knockdown was also assessed on cisplatin-induced ototoxicity. These results demonstrated that cisplatin could activate the HMGB1/RAGE pathway in cochlear hair cells and release inflammatory factors. Pretreatment with FPS-ZM1 alleviated cisplatin-induced ototoxicity in vivo and in vitro. Knocking down HMGB1 and RAGE achieved specific protective effects. Altogether, inhibiting HMGB1/RAGE axis can reverse the increase of ROS accumulation, the activation of apoptosis, and the production of inflammatory reactions after cisplatin injury. FPS-ZM1 could resist the ototoxicity of cisplatin by suppressing the HMGB1/RAGE signal pathway, and it may be considered the new otoprotective potential strategy for hearing loss.

Dabrafenib protects from cisplatin-induced hearing loss in a clinically relevant mouse model

The widely used chemotherapy cisplatin causes permanent hearing loss in 40%-60% of patients with cancer. One drug, sodium thiosulfate, is approved by the FDA for use in pediatric patients with localized solid tumors for preventing cisplatin-induced hearing loss, but more drugs are desperately needed. Here, we tested dabrafenib, an FDA-approved BRAF kinase inhibitor and anticancer drug, in a clinically relevant multidose cisplatin mouse model. The protective effects of dabrafenib, given orally twice daily with cisplatin, were determined by functional hearing tests and cochlear outer hair cell counts. Toxicity of the drug cotreatment was evaluated, and levels of phosphorylated ERK were measured. A dabrafenib dose of 3 mg/kg BW, twice daily, in mice, was determined to be the minimum effective dose, and it is equivalent to one-tenth of the daily FDA-approved dose for human cancer treatment. The levels of hearing protection acquired, 20-25 dB at the 3 frequencies tested, in both female and male mice, persisted for 4 months after completion of treatments. Moreover, dabrafenib exhibited a good in vivo therapeutic index (> 25), protected hearing in 2 mouse strains, and diminished cisplatin-induced weight loss. This study demonstrates that dabrafenib is a promising candidate drug for protection from cisplatin-induced hearing loss.

Adverse health outcomes and global quality of life in long-term testicular cancer survivors: a longitudinal 30-year perspective

BACKGROUND

The aim of this study was to characterize the prevalence of self-reported adverse health outcomes (AHOs), track changes in AHOs, and examine their impact on health-related quality of life (HrQoL) in testicular cancer survivors (TCSs) who were diagnosed between 1980 and 1994. These assessments were conducted during two survey waves (SWs), with the first occurring ∼12 years after surgery-only or platinum-based chemotherapy (PBCT), and the second ∼28 years after initial treatment. The study primarily focused on 'typical AHOs', which included Peripheral Sensory Neuropathy (PSN), Raynaud's phenomenon, Tinnitus, and Hearing loss.

PATIENTS AND METHODS

A total of 427 TCSs were included in the evaluation, distributed as follows: surgery-only group (n = 155), PBCT-standard group with ≤850 mg cisplatin (n = 222), and PBCT-high group with >850 mg cisplatin (n = 50). For comparison of HrQoL, men from the general population served as a control group (referred to as 'Norms'). The statistical significance level was set at P < 0.05, and clinical importance, in terms of testing HrQoL differences, was defined as Δ ≥2.5 points.

RESULTS

A higher number of TCSs who underwent PBCT reported experiencing typical AHOs compared with those who had surgery only. The highest prevalence rates were observed among TCSs who had undergone PBCT-high. Further, the number of TCSs describing typical AHOs, except Raynaud's phenomenon, increased during the observation period of 16 years. At the last SW, a median of 4 AHOs (any type) were reported after PBCT-high compared with a median of 2 AHOs after Surgery-only or after PBCT-standard. With Surgery-only as reference, PBCT-high, but not PBCT-standard, was associated with decreasing physical HrQoL in the last SW (A2 Regression coefficient: -4.3; P = 0.008). When comparing all TCSs with Norms no clinically important difference in physical and mental HrQoL was observed at either SW. However, at the last SW, TCSs after PBCT-high therapy represented a subgroup of TCSs with clinically important impairment of HRQoL. Of the typical AHOs, only PSN reduced HrQoL. Chronic fatigue, pain, anxiety/depression, sexual dysfunction, unemployment, being single, and low education were additional covariates.

CONCLUSIONS

After a median of 28 years since their treatment, HrQoL in TCSs was found to be comparable to that of Norms. This similarity held true even though AHOs, especially after PBCT-high, were becoming more prevalent among TCSs. The study revealed that individuals with a history of PBCT-high are at a high risk of experiencing a significantly increased prevalence of long-term AHOs, which subsequently leads to diminished HrQoL. It is crucial to recognize and provide specialized attention to these TCSs during lifelong follow-up care.

Evaluation of the therapeutic effects of arbutin on cisplatin-induced ovarian toxicity in rats through endoplasmic reticulum stress and Nrf2 pathway

Arbutin (ARB) is a glycosylated hydroquinone with potent antioxidant effects. Although cisplatin (CP) is widely used in chemotherapy, its toxicity in healthy tissues, including ovotoxicity, is an insurmountable problem. This study aimed to evaluate the therapeutic effect of ARB against CP-related ovototoxicity by including nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in rats for the first time. Rats treated one dose of CP (5 mg/kg) on the first day, followed by ARB (5 and 10 mg/kg) for three days. Serum reproductive hormone levels were determined using ELISA kits. Oxidative stress (OS), inflammation, endoplasmic reticulum stress (ERS) and apoptosis markers in ovarian tissue were also determined colorimetrically. In addition, how CP affects Nrf2 pathway and the effect of ARB on this situation were also addressed. ARB treatment reduced the levels of markers of OS, inflammation, ERS and apoptosis in ovarian tissue of CP-stimulated animals. ARB regenerated the depleted antioxidant system by triggering Nrf2 pathway in the ovarian tissues of animals stimulated by CP. Histological findings also supported the therapeutic efficacy of ARB. The results indicate that ARB may have therapeutic effects against CP-induced reproductive toxicity with its Nrf2 activator potential. ARB should be tested in more extensive studies as a new generation chemopreventive candidate molecule.

The Relevance of Autophagy within Inner Ear in Baseline Conditions and Tinnitus-Related Syndromes

Tinnitus is the perception of noise in the absence of acoustic stimulation (phantom noise). In most patients suffering from chronic peripheral tinnitus, an alteration of outer hair cells (OHC) starting from the stereocilia (SC) occurs. This is common following ototoxic drugs, sound-induced ototoxicity, and acoustic degeneration. In all these conditions, altered coupling between the tectorial membrane (TM) and OHC SC is described. The present review analyzes the complex interactions involving OHC and TM. These need to be clarified to understand which mechanisms may underlie the onset of tinnitus and why the neuropathology of chronic degenerative tinnitus is similar, independent of early triggers. In fact, the fine neuropathology of tinnitus features altered mechanisms of mechanic-electrical transduction (MET) at the level of OHC SC. The appropriate coupling between OHC SC and TM strongly depends on autophagy. The involvement of autophagy may encompass degenerative and genetic tinnitus, as well as ototoxic drugs and acoustic trauma. Defective autophagy explains mitochondrial alterations and altered protein handling within OHC and TM. This is relevant for developing novel treatments that stimulate autophagy without carrying the burden of severe side effects. Specific phytochemicals, such as curcumin and berberin, acting as autophagy activators, may mitigate the neuropathology of tinnitus.

Molecular Characteristics of Cisplatin-Induced Ototoxicity and Therapeutic Interventions

Cisplatin is a commonly used chemotherapeutic agent with proven efficacy in treating various malignancies, including testicular, ovarian, cervical, breast, bladder, head and neck, and lung cancer. Cisplatin is also used to treat tumors in children, such as neuroblastoma, osteosarcoma, and hepatoblastoma. However, its clinical use is limited by severe side effects, including ototoxicity, nephrotoxicity, neurotoxicity, hepatotoxicity, gastrointestinal toxicity, and retinal toxicity. Cisplatin-induced ototoxicity manifests as irreversible, bilateral, high-frequency sensorineural hearing loss in 40-60% of adults and in up to 60% of children. Hearing loss can lead to social isolation, depression, and cognitive decline in adults, and speech and language developmental delays in children. Cisplatin causes hair cell death by forming DNA adducts, mitochondrial dysfunction, oxidative stress, and inflammation, culminating in programmed cell death by apoptosis, necroptosis, pyroptosis, or ferroptosis. Contemporary medical interventions for cisplatin ototoxicity are limited to prosthetic devices, such as hearing aids, but these have significant limitations because the cochlea remains damaged. Recently, the U.S. Food and Drug Administration (FDA) approved the first therapy, sodium thiosulfate, to prevent cisplatin-induced hearing loss in pediatric patients with localized, non-metastatic solid tumors. Other pharmacological treatments for cisplatin ototoxicity are in various stages of preclinical and clinical development. This narrative review aims to highlight the molecular mechanisms involved in cisplatin-induced ototoxicity, focusing on cochlear inflammation, and shed light on potential antioxidant and anti-inflammatory therapeutic interventions to prevent or mitigate the ototoxic effects of cisplatin. We conducted a comprehensive literature search (Google Scholar, PubMed) focusing on publications in the last five years.

Macrophage Depletion Protects Against Cisplatin-Induced Ototoxicity and Nephrotoxicity

Cisplatin is a widely used and highly effective anti-cancer drug with significant side effects including ototoxicity and nephrotoxicity. Macrophages, the major resident immune cells in the cochlea and kidney, are important drivers of both inflammatory and tissue repair responses. To investigate the roles of macrophages in cisplatin-induced ototoxicity and nephrotoxicity, we used PLX3397, an FDA-approved inhibitor of the colony-stimulating factor 1 receptor (CSF1R), to eliminate tissue-resident macrophages during the course of cisplatin administration. Mice treated with cisplatin alone (cisplatin/vehicle) had significant hearing loss (ototoxicity) as well as kidney injury (nephrotoxicity). Macrophage ablation using PLX3397 resulted in significantly reduced hearing loss measured by auditory brainstem responses (ABR) and distortion-product otoacoustic emissions (DPOAE). Sensory hair cells in the cochlea were protected against cisplatin-induced death in mice treated with PLX3397. Macrophage ablation also protected against cisplatin-induced nephrotoxicity, as evidenced by markedly reduced tubular injury and fibrosis as well as reduced plasma blood urea nitrogen (BUN) and neutrophil gelatinase-associated lipocalin (NGAL) levels. Mechanistically, our data suggest that the protective effect of macrophage ablation against cisplatin-induced ototoxicity and nephrotoxicity is mediated by reduced platinum accumulation in both the inner ear and the kidney. Together our data indicate that ablation of tissue-resident macrophages represents a novel strategy for mitigating cisplatin-induced ototoxicity and nephrotoxicity.

Brief summary

Macrophage ablation using PLX3397 was protective against cisplatin-induced ototoxicity and nephrotoxicity by limiting platinum accumulation in the inner ear and kidney.

KSR1 knockout mouse model demonstrates MAPK pathway's key role in cisplatin- and noise-induced hearing loss

Hearing loss is a major disability in everyday life and therapeutic interventions to protect hearing would benefit a large portion of the world population. Here we found that mice devoid of the protein kinase suppressor of RAS 1 (KSR1) in their tissues (germline KO mice) exhibit resistance to both cisplatin- and noise-induced permanent hearing loss compared to their wild-type KSR1 littermates. KSR1 is expressed in the cochlea and is a scaffold protein that brings in proximity the mitogen-activated protein kinase (MAPK) proteins BRAF, MEK and ERK and assists in their activation through a phosphorylation cascade induced by both cisplatin and noise insults in the cochlear cells. Deleting the KSR1 protein tempered down the MAPK phosphorylation cascade in the cochlear cells following both cisplatin and noise insults and conferred hearing protection of up to 30 dB SPL in three tested frequencies in mice. Treatment with dabrafenib, an FDA-approved oral BRAF inhibitor, downregulated the MAPK kinase cascade and protected the KSR1 wild-type mice from both cisplatin- and noise-induced hearing loss. Dabrafenib treatment did not enhance the protection of KO KSR1 mice, as excepted, providing evidence dabrafenib works primarily through the MAPK pathway. Thus, either elimination of the KSR1 gene expression or drug inhibition of the MAPK cellular pathway in mice resulted in profound protection from both cisplatin- and noise-induce hearing loss. Inhibition of the MAPK pathway, a cellular pathway that responds to damage in the cochlear cells, can prove a valuable strategy to protect and treat hearing loss.

3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMGCR) protects hair cells from cisplatin-induced ototoxicity in vitro: possible relation to the activities of p38 MAPK signaling pathway

The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMGCR) gene encodes rate-limiting enzyme in cholesterol biosynthesis, which is related to cell proliferation and mitochondrial function. The present study was designed to explore the expression of HMGCR in murine cochlear hair cells and HEI-OC1 cells and the possible mechanisms underpinning the actions of HMGCR in cisplatin-induced ototoxicity, with special attention given to p38 mitogen-activated protein kinase (MAPK) activities in vitro. The expressions of HMGCR, p-p38, cleaved caspase-3 and LC3B was measured by immunofluorescence and western blot. JC-1 staining and MitoSOX Red were used to detect mitochondria membrane potential (MMP) and reactive oxygen species (ROS) levels respectively. The apoptosis of auditory cells was assessed by TUNEL staining and flow cytometry. Protein levels of bcl2/bax and beclin1 were examined by western blot. We found that HMGCR was widely expressed in the auditory cells, of both neonatal mice and 2-month-old mice, in cytoplasm, nucleus and stereocilia. Moreover, 30 μM cisplatin elicited the formation of ROS, which, in turn, led to HMGCR reduction, activating p38 kinase-related apoptosis and autophagy in auditory cells. Meanwhile, co-treatment with ROS scavenger at a concentration of 2 mM, N-acetyl-L-cysteine (NAC), could alleviate the aforementioned changes. In addition, HMGCR silencing resulted in higher p38 MAPK-mediated apoptosis and autophagy under cisplatin injury. Taken together, we demonstrate that, for the first time, that HMGCR is expressed in the cochlear. Furthermore, HMGCR exerts protective benefit on auditory cells against cisplatin-mediated injury stimulated by ROS, culminating in regulation of p38 MAPK-dependent apoptosis and autophagy.

ERK1/2 Inhibition Alleviates Noise-Induced Hearing Loss While Tempering Down the Immune Response

Noise-induced hearing loss (NIHL) is a major cause of hearing impairment, yet no FDA-approved drugs exist to prevent it. Targeting the mitogen activated protein kinase (MAPK) cellular pathway has emerged as a promising approach to attenuate NIHL. Tizaterkib is an orally bioavailable, highly specific ERK1/2 inhibitor, currently in Phase-1 anticancer clinical trials. Here, we tested tizaterkib's efficacy against permanent NIHL in mice at doses equivalent to what humans are currently prescribed in clinical trials. The drug given orally 24 hours after noise exposure, protected an average of 20-25 dB SPL in three frequencies, in female and male mice, had a therapeutic window >50, and did not confer additional protection to KSR1 genetic knockout mice, showing the drug works through the MAPK pathway. Tizaterkib shielded from noise-induced cochlear synaptopathy, and a 3-day, twice daily, treatment with the drug was the optimal determined regimen. Importantly, tizaterkib was shown to decrease the number of CD45 and CD68 positive immune cells in the cochlea following noise exposure, which could be part of the protective mechanism of MAPK inhibition.

Carbon Monoxide-Loaded Red Blood Cell Prevents the Onset of Cisplatin-Induced Acute Kidney Injury

Cisplatin-induced acute kidney injury (AKI) is an important factor that limits the clinical use of this drug for the treatment of malignancies. Oxidative stress and inflammation are considered to be the main causes of not only cisplatin-induced death of cancer cells but also cisplatin-induced AKI. Therefore, developing agents that exert antioxidant and anti-inflammatory effects without weakening the anti-tumor effects of cisplatin is highly desirable. Carbon monoxide (CO) has recently attracted interest due to its antioxidant, anti-inflammatory, and anti-tumor properties. Herein, we report that CO-loaded red blood cell (CO-RBC) exerts renoprotective effects on cisplatin-induced AKI. Cisplatin treatment was found to reduce cell viability in proximal tubular cells via oxidative stress and inflammation. Cisplatin-induced cytotoxicity, however, was suppressed by the CO-RBC treatment. The intraperitoneal administration of cisplatin caused an elevation in the blood urea nitrogen and serum creatinine levels. The administration of CO-RBC significantly suppressed these elevations. Furthermore, the administration of CO-RBC also reduced the deterioration of renal histology and tubular cell injury through its antioxidant and anti-inflammatory effects in cisplatin-induced AKI mice. Thus, our data suggest that CO-RBC has the potential to substantially prevent the onset of cisplatin-induced AKI, which, in turn, may improve the usefulness of cisplatin-based chemotherapy.

Activation of Nrf2 inhibits ferroptosis and protects against oxaliplatin-induced ototoxicity

Oxaliplatin, as a third-generation platinum-based anticancer drug, is widely used in tumor therapy of many systems. Clinically, oxaliplatin has a number of serious side effects, most notably neuropathy and ototoxicity. The degeneration of cochlear hair cells is the main reason for the hearing loss caused by platinum-based drugs. However, the mechanism of oxaliplatin-induced cochlear hair cell death remains unclear. Ferroptosis is a novel cell injury pattern triggered by the accumulation of iron hydroperoxides in lipids and dependent on the participation of iron ions, which plays an important role in a variety of diseases. Whether ferroptosis is involved in oxaliplatin-induced ototoxicity has not been reported. In this study, we observed that oxaliplatin treatment resulted in lipid peroxidation and reactive oxygen species (ROS) accumulation in OC1 cells, which may be an early alteration in the occurrence of ferroptosis. Additional treatment with ferroptosis inducer or inhibitor significantly aggravated or ameliorated oxaliplatin-induced cytotoxicity. Similarly, inhibition of ferroptosis also protected cochlear hair cells against oxaliplatin-induced injury. In addition, the expression of nuclear factor erythroid 2-related factor2 (Nrf2) and heme oxygenase-1 (HO-1) was significantly increased after oxaliplatin treatment, and treatment with the Nrf2 agonist, resveratrol, dramatically attenuated cochlear hair cell damage induced by oxaliplatin. Activation of Nrf2 significantly decreased the expression of iron regulatory protein 2 (IRP-2) and reversed the expression of glutathione peroxidase 4 (GPX4). Collectively, our results demonstrated that activation of Nrf2 alleviates oxaliplatin-induced cochlear hair cell damage by inhibiting ferroptosis, which may be a new mechanism of oxaliplatin-induced 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.

Advances in the roles of glycyrrhizic acid in cancer therapy

Since the first 70 years of reporting cancer chemotherapy, malignant tumors have been the second most common cause of death in children and adults. Currently, the commonly used anti-cancer methods include surgery, chemotherapy, radiotherapy, and immunotherapy. Although these treatment methods could alleviate cancer, they lead to different forms of side effects and have no particularly significant effect on prolonging the patients' life span. Glycyrrhizic acid (GL), a native Chinese herbal extract, has a wide range of pharmacological effects, such as anti-cancer, anti-inflammatory, antioxidant, and immune regulation. In this review, the anti-cancer effects and mechanisms of GL are summarized in various cancers. The inhibition of GL on chemotherapy-induced side effects, including hepatotoxicity, nephrotoxicity, genotoxicity, neurotoxicity and pulmonary toxicity, is highlighted. Therefore, GL may be a promising and ideal drug for cancer therapy.

SIRT3/GLUT4 signaling activation by metformin protect against cisplatin-induced ototoxicity in vitro

Cisplatin is highly effective for killing tumor cells. However, as one of its side effects, ototoxicity limits the clinical application of cisplatin. The mechanisms of cisplatin-induced ototoxicity have not been fully clarified yet. SIRT3 is a deacetylated protein mainly located in mitochondria, which regulates a variety of physiological processes in cells. The role of SIRT3 in cisplatin-induced hair cell injury has not been founded. In this study, primary cultured cochlear explants exposed to 5 μM cisplatin, as well as OC-1 cells exposed to 10 μM cisplatin, were used to establish models of cisplatin-induced ototoxicity in vitro. We found that when combined with cisplatin, metformin (75 μM) significantly up-regulated the expression of SIRT3 and alleviated cisplatin-induced apoptosis of hair cells. We regulated the expression of SIRT3 to explore the role of SIRT3 in cisplatin-induced auditory hair cell injury. Overexpression of SIRT3 promoted the survival of auditory hair cells and alleviated the apoptosis of auditory hair cells. In contrast, knockdown of SIRT3 impaired the protective effect of metformin and exacerbated cisplatin injury. In addition, we found that the protective effect of SIRT3 may be achieved by regulating GLUT4 translocation and rescuing impaired glucose uptake caused by cisplatin. Our study confirmed that upregulation of SIRT3 may antagonize cisplatin-induced ototoxicity, and provided a new perspective for the study of cisplatin-induced ototoxicity.

Protective Effect of Avenanthramide-C on Auditory Hair Cells against Oxidative Stress, Inflammatory Cytokines, and DNA Damage in Cisplatin-Induced Ototoxicity

Cisplatin-induced ototoxicity leads to hearing impairment, possibly through reactive oxygen species (ROS) production and DNA damage in cochlear hair cells (HC), although the exact mechanism is unknown. Avenanthramide-C (AVN-C), a natural, potent antioxidant, was evaluated in three study groups of normal adult C57Bl/6 mice (control, cisplatin, and AVN-C+cisplatin) for the prevention of cisplatin-induced hearing loss. Auditory brainstem responses and immunohistochemistry of outer hair cells (OHCs) were ascertained. Cell survival, ROS production, Phospho-H2AX-enabled tracking of DNA damage-repair kinetics, and expression levels of inflammatory cytokines (TNF-α, IL-1β, IL6, iNOS, and COX2) were assessed using House Ear Institute-Organ of Corti 1 (HEI-OC1 Cells). In the in vivo mouse model, following cisplatin-induced damage, AVN-C decreased the hearing thresholds and sheltered all cochlear turns' OHCs. In HEI-OC1 cells, AVN-C preserved cell viability and decreased ROS production, whereas cisplatin enhanced both ROS levels and cell viability. In HEI-OC1 cells, AVN-C downregulated IL6, IL-1β, TNF-α, iNOS, and COX2 production that was upregulated by cisplatin treatment. AVN-C attenuated the cisplatin-enhanced nuclear H2AX activation. AVN-C had a strong protective effect against cisplatin-induced ototoxicity through inhibition of ROS and inflammatory cytokine production and DNA damage and is thus a promising candidate for preventing cisplatin-induced sensorineural hearing loss.

Emerging and established therapies for chemotherapy-induced ototoxicity

PURPOSE

Ototoxicity is considered a dose-limiting side effect of some chemotherapies. Hearing loss, in particular, can have significant implications for the quality of life for cancer survivors. Here, we review therapeutic approaches to mitigating ototoxicity related to chemotherapy.

METHODS

Literature review.

CONCLUSIONS

Numerous otoprotection strategies are undergoing active investigation. However, numerous challenges exist to confer adequate protection while retaining the anti-cancer efficacy of the chemotherapy.

IMPLICATIONS FOR CANCER SURVIVORS

Ototoxicity can have significant implications for cancer survivors, notably those receiving cisplatin. Clinical translation of multiple otoprotection approaches will aid in limiting these consequences.

Deciphering the sequential changes of monocytes/macrophages in the progression of IDD with longitudinal approach using single-cell transcriptome

Intervertebral disk degeneration (IDD) is a chronic inflammatory disease with intricate connections between immune infiltration and oxidative stress (OS). Complex cell niches exist in degenerative intervertebral disk (IVD) and interact with each other and regulate the disk homeostasis together. However, few studies have used longitudinal approach to describe the immune response of IDD progression. Here, we conducted conjoint analysis of bulk-RNA sequencing and single-cell sequencing, together with a series of techniques like weighted gene co-expression network analysis (WGCNA), immune infiltration analysis, and differential analysis, to systematically decipher the difference in OS-related functions of different cell populations within degenerative IVD tissues, and further depicted the longitudinal alterations of immune cells, especially monocytes/macrophages in the progression of IDD. The OS-related genes CYP1A1, MMP1, CCND1, and NQO1 are highly expressed and might be diagnostic biomarkers for the progression of IDD. Further landscape of IVD microenvironment showed distinct changes in cell proportions and characteristics at late degeneration compared to early degeneration of IDD. Monocytes/macrophages were classified into five distinct subpopulations with different roles. The trajectory lineage analysis revealed transcriptome alterations from effector monocytes/macrophages and regulatory macrophages to other subtypes during the evolution process and identified monocytes/macrophage subpopulations that had rapidly experienced the activation of inflammatory or anti-inflammatory responses. This study further proposed that personalized therapeutic strategies are needed to be formulated based on specific monocyte/macrophage subtypes and degenerative stages of IDD.

Fabrication and application of cisplatin-loaded mesoporous magnetic nanobiocomposite: a novel approach to smart cervical cancer chemotherapy

There are significant challenges in developing drug carriers for therapeutic perspective. We have investigated a novel nanocarrier system, based on combining functionalized magnetic nanocomposite with Metal–Organic Frameworks (MOFs). Magnetic nanoparticles modified using biocompatible copolymers may be suitable for delivering hydrophobic drugs, such as cisplatin. Furthermore, compared to polymeric nanocarriers, nanocomposite constructed from zeolitic imidazolate framework-8 (ZIF-8) have demonstrated better drug loading capacity, as well as excellent pH-triggered drug release. Cisplatin-encapsulated Fe3O4@SiO2-ZIF-8@N-Chit-FA has been evaluated to determine the antitumor effects of free cisplatin enhancement in cervical cancer cells. In order to increase the stability of the proposed nanocarrier in aqueous solutions, in addition to the density of functional groups, a nano-chitosan layer was coated on top of the magnetic nanocomposite. It was then added with cisplatin onto the surface of Fe3O4@SiO2-ZIF-8@N-Chit-FA to deliver anticancer treatment that could be targeted using a magnetic field. A mouse isograft model of TC1 cells was used to evaluate the in vivo tumor growth inhibition. In tumor-bearing mice, Fe3O4@SiO2-ZIF-8@N-Chit-FA-cisplatin was injected intraperitoneally, and the targeted delivery was amplified by an external magnet (10 mm by 10 mm, surface field strength 0.4 T) fixed over the tumor site. Based on in vivo results, cisplatin-Loaded Mesoporous Magnetic Nanobiocomposite inhibited the growth of cervical tumors (P < 0.001) through the induction of tumor necrosis (P < 0.05) when compared to cisplatin alone. With the application of an external magnetic field, the drug was demonstrated to be able to induce its effects on specific target areas. In summary, Fe3O4 @ SiO2-ZIF-8 @ N-Chit-FA nanocomposites have the potential to be implemented in targeted nanomedicine to deliver bio-functional molecules.

Diagnostic and predictive values of serum metabolic profiles in sudden sensorineural hearing loss patients

Sudden sensorineural hearing loss (SSNHL) is an otologic emergency, and metabolic disturbance is involved in its pathogenesis. This study recruited 20 SSNHL patients and 20 healthy controls (HCs) and collected their serum samples. Serum metabolites were detected by liquid chromatography-mass spectrometry, and metabolic profiles were analyzed. All patients were followed up for 3 months and categorized into recovery and non-recovery groups. The distinctive metabolites were assessed between two groups, and their predictive values for hearing recovery were evaluated. Analysis results revealed that SSNHL patients exhibited significantly characteristic metabolite signatures compared to HCs. The top 10 differential metabolites were further analyzed, and most of them showed potential diagnostic values based on receiver operator characteristic (ROC) curves. Finally, 14 SSNHL patients were divided into the recovery group, and six patients were included in the non-recovery group. Twelve distinctive metabolites were observed between the two groups, and ROC curves demonstrated that N4-acetylcytidine, p-phenylenediamine, sphingosine, glycero-3-phosphocholine, and nonadecanoic acid presented good predictabilities in the hearing recovery. Multivariate analysis results demonstrated that serum N4-Acetylcytidine, sphingosine and nonadecanoic acid levels were associated with hearing recovery in SSNHL patients. Our results identified that SSNHL patients exhibited distinctive serum metabolomics signatures, and several serum biomarkers were proved to be potential in predicting hearing recovery. The discriminative metabolites might contribute to illustrating the mechanisms of SSNHL and provide possible clues for its treatments.

Exosomes Derived from Bone Marrow-Mesenchymal Stem Cells Attenuates Cisplatin-Induced Ototoxicity in a Mouse Model

Background: Both hypoxia preconditioning and exosomes derived from bone marrow mesenchymal stem cells (BMSC-Exo) have been adopted to alleviate hair-loss-related ototoxicity. Whether hypoxic BMSCs-derived exosomes (hypBMSC-Exo) could alleviate cisplatin-induced ototoxicity is investigated in this study. Methods: Cisplatin intraperitoneally injected C57BL/6 mice were trans-tympanically administered BMSC-Exo or hypBMSC-Exo in the left ear. Myosin 7a staining was utilized to detect mature hair cells. Auditory brainstem response (ABR) was assessed to indicate auditory sensitivity at 8, 16, 24, and 32 kHz. The relative expressions of hypoxia-inducible factor-1α (HIF-1α), superoxide dismutase 1 (SOD1), and SOD2 were determined with RT-PCR and Western blot. The content of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), SOD, and glutathione (GSH) in the middle turns of the cochlea were measured. Results: Up-regulated HIF-1α expression was observed in hypBMSC-Exo compared with BMSC-Exo. Diminished auditory sensitivity and increased hair cell loss was observed in the cisplatin-exposed mice with increased content of H₂O₂ and MDA and decreased content of SOD and GSH, which could be reversed by hypBMSC-Exo or BMSC-Exo administration. It is worth noting that hypBMSC-Exo demonstrated more treatment benefits than BMSC-Exo with up-regulated SOD1 and SOD2 expression in the middle turns of the cochlea tissues. Conclusions: Hypoxic preconditioning may provide a new therapeutic option in regenerative medicine, and hypBMSC-Exo could be utilized to alleviate cisplatin-induced ototoxicity.

The Effect of β-Carotene, Tocopherols and Ascorbic Acid as Anti-Oxidant Molecules on Human and Animal In Vitro/In Vivo Studies: A Review of Research Design and Analytical Techniques Used

Prolonged elevated oxidative stress (OS) possesses negative effect on cell structure and functioning, and is associated with the development of numerous disorders. Naturally occurred anti-oxidant compounds reduce the oxidative stress in living organisms. In this review, antioxidant properties of β-carotene, tocopherols and ascorbic acid are presented based on in vitro, in vivo and populational studies. Firstly, environmental factors contributing to the OS occurrence and intracellular sources of Reactive Oxygen Species (ROS) generation, as well as ROS-mediated cellular structure degradation, are introduced. Secondly, enzymatic and non-enzymatic mechanism of anti-oxidant defence against OS development, is presented. Furthermore, ROS-preventing mechanisms and effectiveness of β-carotene, tocopherols and ascorbic acid as anti-oxidants are summarized, based on studies where different ROS-generating (oxidizing) agents are used. Oxidative stress biomarkers, as indicators on OS level and prevention by anti-oxidant supplementation, are presented with a focus on the methods (spectrophotometric, fluorometric, chromatographic, immuno-enzymatic) of their detection. Finally, the application of Raman spectroscopy and imaging as a tool for monitoring the effect of anti-oxidant (β-carotene, ascorbic acid) on cell structure and metabolism, is proposed. Literature data gathered suggest that β-carotene, tocopherols and ascorbic acid possess potential to mitigate oxidative stress in various biological systems. Moreover, Raman spectroscopy and imaging can be a valuable technique to study the effect of oxidative stress and anti-oxidant molecules in cell studies.

Polystyrene microplastics induced oxidative stress, inflammation and necroptosis via NF-κB and RIP1/RIP3/MLKL pathway in chicken kidney

Microplastics (MPs) are a novel environment pollutant widespread among the natural environment, also causing damage to aquatic animals and mammals. However, their effects on the kidney of poultry are still unclear. In this study, chickens were exposure to the different doses of PS-MPs (1, 10, 100 mg/L) for six weeks, with 1 mg/L being the environmental concentration. The effects of PS-MPs on renal tissue damage in chicken were analyzed. Our results suggested that MPs exposure causes mitochondrial morphology and dysbiosis (MFN1/2, OPA1, Drp1), mitochondrial structural damage by triggering imbalance in mitochondrial dynamics. Antioxidant enzyme (SOD, CAT, MDA, GSH, T-AOC) activity was significantly altered, which in turn caused oxidative stress. H&E staining results showed damage and inflammation of chicken kidney. Mechanistically, the inflammation featured by activated NF-κB P65 and increased expression of pro-inflammatory factors (TNFα, iNOs, IL-1β and IL-6). Moreover, PS-MPs intake induced necroptosis through activated RIP1/RIP3/MLKL signaling pathway. In conclusion, our study was the first to show that oral intake of PS-MPs induced inflammation and necroptosis in chicken kidney and the differences in damage were linked to the concentration of PS-MPs. The purpose of this study provided theoretical support for the environmental risk assessment of PS-MPs.

Repositioning of Lansoprazole as a Protective Agent Against Cisplatin-Induced Ototoxicity

Cisplatin (CDDP) is a well-known chemotherapeutic drug approved for various cancers. However, CDDP accumulates in the inner ear cochlea via organic cation transporter 2 (OCT2) and causes ototoxicity, which is a major clinical limitation. Since lansoprazole (LPZ), a proton pump inhibitor, is known to inhibit OCT2-mediated transport of CDDP, we hypothesized that LPZ might ameliorate CDDP-induced ototoxicity (CIO). To test this hypothesis, we utilized in vivo fluorescence imaging of zebrafish sensory hair cells. The fluorescence signals in hair cells in zebrafish treated with CDDP dose-dependently decreased. Co-treatment with LPZ significantly suppressed the decrease of fluorescence signals in zebrafish treated with CDDP. Knockout of a zebrafish homolog of OCT2 also ameliorated the reduction of fluorescence signals in hair cells in zebrafish treated with CDDP. These in vivo studies suggest that CDDP damages the hair cells of zebrafish through oct2-mediated accumulation and that LPZ protects against CIO, possibly inhibiting the entry of CDDP into the hair cells via oct2. We also evaluated the otoprotective effect of LPZ using a public database containing adverse event reports. The analysis revealed that the incidence rate of CIO was significantly decreased in patients treated with LPZ. We then retrospectively analyzed the medical records of Mie University Hospital to examine the otoprotective effect of LPZ. The incidence rate of ototoxicity was significantly lower in patients co-treated with LPZ compared to those without LPZ. These retrospective findings suggest that LPZ is also protective against CIO in humans. Taken together, co-treatment with LPZ may reduce the risk of CIO.

NADPH Oxidase 3 Deficiency Protects From Noise-Induced Sensorineural Hearing Loss

The reactive oxygen species (ROS)-generating NADPH oxidase NOX3 isoform is highly and specifically expressed in the inner ear. NOX3 is needed for normal vestibular development but NOX-derived ROS have also been implicated in the pathophysiology of sensorineural hearing loss. The role of NOX-derived ROS in noise-induced hearing loss, however, remains unclear and was addressed with the present study. Two different mouse strains, deficient in NOX3 or its critical subunit p22phox, were subjected to a single noise exposure of 2 h using an 8-16 kHz band noise at an intensity of 116-120 decibel sound pressure level. In the hours following noise exposure, there was a significant increase in cochlear mRNA expression of NOX3 in wild type animals. By using RNAscope in situ hybridization, NOX3 expression was primarily found in the Rosenthal canal area, colocalizing with auditory neurons. One day after the noise trauma, we observed a high frequency hearing loss in both knock-out mice, as well as their wild type littermates. At day seven after noise trauma however, NOX3 and p22phox knockout mice showed a significantly improved hearing recovery and a marked preservation of neurosensory cochlear structures compared to their wild type littermates. Based on these findings, an active role of NOX3 in the pathophysiology of noise-induced hearing loss can be demonstrated, in line with recent evidence obtained in other forms of acquired hearing loss. The present data demonstrates that the absence of functional NOX3 enhances the hearing recovery phase following noise trauma. This opens an interesting clinical window for pharmacological or molecular intervention aiming at post prevention of noise-induced hearing loss.

The Mechanotransduction Channel and Organic Cation Transporter Are Critical for Cisplatin Ototoxicity in Murine Hair Cells

Cisplatin is one of the most widely used chemotherapeutic drugs across the world. However, the serious ototoxic effects, leading to permanent hair cell death and hearing loss, significantly limit the utility of cisplatin. In zebrafish, the functional mechanotransduction channel is required for cisplatin ototoxicity. However, it is still unclear the extent to which the mechanotransduction channel is involved in cisplatin uptake and ototoxicity in mammalian hair cells. Herein, we show that genetically disrupting mechanotransduction in mouse partially protects hair cells from cisplatin-induced hair cell death. Using a fluorescent-dye conjugated cisplatin, we monitored cisplatin uptake in cochlear explants and found that functional mechanotransduction is required for the uptake of cisplatin in murine hair cells. In addition, cimetidine, an inhibitor of the organic cation transporter, also partially protects hair cells from cisplatin ototoxicity. Notably, the otoprotective effects of cimetidine do not require mechanotransduction. These findings suggest that both the mechanotransduction channel and the organic cation transporter are critical for cisplatin ototoxicity in murine hair cells.