Inhaled hydrogen gas therapy for prevention of noise-induced hearing loss through reducing reactive oxygen species

The Landscape of Smart Biomaterial-Based Hydrogen Therapy

Hydrogen (H2) therapy is an emerging, novel, and safe therapeutic modality that uses molecular hydrogen for effective treatment. However, the impact of H2 therapy is limited because hydrogen molecules predominantly depend on the systemic administration of H2 gas, which cannot accumulate at the lesion site with high concentration, thus leading to limited targeting and utilization. Biomaterials are developed to specifically deliver H2 and control its release. In this review, the development process, stimuli-responsive release strategies, and potential therapeutic mechanisms of biomaterial-based H2 therapy are summarized. H2 therapy. Specifically, the produced H2 from biomaterials not only can scavenge free radicals, such as reactive oxygen species (ROS) and lipid peroxidation (LPO), but also can inhibit the danger factors of initiating diseases, including pro-inflammatory cytokines, adenosine triphosphate (ATP), and heat shock protein (HSP). In addition, the released H2 can further act as signal molecules to regulate key pathways for disease treatment. The current opportunities and challenges of H2-based therapy are discussed, and the future research directions of biomaterial-based H2 therapy for clinical applications are emphasized.

The impact of hydrogen inhalation therapy on blood reactive oxygen species levels: A randomized controlled study

Reactive Oxygen Species (ROS) play a key role in physiological processes. However, the imbalance between ROS and antioxidants in favor of the former causes oxidative stress linked to numerous pathologies. Due to its unique attributes, including distinguished permeability and selective antioxidant capability, molecular hydrogen (H2) has become an essential therapeutic agent. Hydrogen Inhalation Therapy (HIT) has come to light as a promising strategy to counteract oxidative stress. In this randomized controlled study, we aimed to evaluate the effectiveness of HIT in reducing blood ROS levels. 37 participants with elevated ROS levels (d-ROMs value > 350 U.CARR) were enrolled in the study. Participants were divided into test and control groups. The test group participants received HIT, and then their blood ROS levels were measured immediately post-treatment and after 24 h. Their results were compared to those of the control group participants who did not undergo HIT. The test group demonstrated a significant reduction in blood ROS levels after the treatment. These findings suggested the efficacy of HIT in reducing oxidative stress.

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

Systemic health effects of noise exposure

Noise, any unwanted sound, is pervasive and impacts large populations worldwide. Investigators suggested that noise exposure not only induces auditory damage but also produces various organ system dysfunctions. Although previous reviews primarily focused on noise-induced cardiovascular and cerebral dysfunctions, this narrow focus has unintentionally led the research community to disregard the importance of other vital organs. Indeed, limited studies revealed that noise exposure impacts other organs including the liver, kidneys, pancreas, lung, and gastrointestinal tract. Therefore, the aim of this review was to examine the effects of noise on both the extensively studied organs, the brain and heart, but also determine noise impact on other vital organs. The goal was to illustrate a comprehensive understanding of the systemic effects of noise. These systemic effects may guide future clinical research and epidemiological endpoints, emphasizing the importance of considering noise exposure history in diagnosing various systemic diseases.

A double-blinded, randomized controlled clinical trial of hydrogen inhalation therapy for idiopathic sudden sensorineural hearing loss

Background

Hydrogen (H₂) has been reported to be effective in reducing hearing loss due to several causes in animal studies. However, no study has examined the effectiveness of H₂ in treating hearing loss in humans. Thus, we investigated whether H₂ is effective for the treatment of idiopathic sudden sensorineural hearing loss (ISSNHL).

Materials and methods

We conducted a double-blind randomized controlled trial at six hospitals between June 2019 and March 2022. The study protocol and trial registration have been published in the Japan Registry of Clinical Trials (jRCT, No. jRCTs06119004). We randomly assigned patients with ISSNHL to receive either H₂ (H₂ group) or air as a placebo (control group) through inhalation combined with the administration of systemic glucocorticoids and prostaglandin E1. The primary outcome was the hearing threshold and changes in hearing threshold 3 months after therapy. In contrast, the secondary outcomes included the proportion of patients with a good prognosis (complete recovery or marked improvement).

Results

Sixty-five patients with ISSNHL (31 and 34 in the H₂ and control groups, respectively) were included in this study. The hearing threshold 3 months after treatment was not significantly different between the groups; 39.0 decibels (dB) (95% confidence interval [CI]: 28.7-49.3) and 49.5 dB (95% CI: 40.3-58.7) in the H₂ and control groups, respectively. In contrast, the changes in hearing threshold 3 months after treatment was 32.7 dB (95% CI: 24.2-41.3) and 24.2 dB (95% CI: 18.1-30.3) in the H₂ and control groups, respectively. Consequently, the changes in hearing threshold were significantly better in the H₂ group than in the control group (P = 0.048). However, no adverse effects due to the inhalation of H₂ gas have been reported.

Conclusion

This is the first study to investigate the efficacy of H₂ for the treatment of ISSNHL in humans. The results suggest that H₂ therapy may be effective for ISSNHL treatment.

Clinical trial registration

[https://jrct.niph.go.jp/re/reports/detail/10442], identifier [jRCTs06119004].

Hydrogen Gas Inhalation Attenuates Acute Impulse Noise Trauma: A Preclinical In Vivo Study

OBJECTIVE

Molecular hydrogen (H₂) has shown therapeutic potential in several oxidative stress-related conditions in humans, is well-tolerated, and is easily administered via inhalation.The aim of this preclinical in vivo study was to investigate whether impulse noise trauma can be prevented by H₂ when inhaled immediately after impulse noise exposure.

METHODS

Guinea pigs (n = 26) were subjected to impulse noise (n = 400; 156 dB SPL; 0.33/s; n = 11; the Noise group), to impulse noise immediately followed by H₂ inhalation (2 mol%; 500 ml/min; 1 hour; n = 10; the Noise + H₂ group), or to H₂ inhalation (n = 5; the H₂ group). The acoustically evoked ABR threshold at 3.15, 6.30, 12.5, 20.0, and 30.0 kHz was assessed before and 4 days after impulse noise and/or H₂ exposure. The cochleae were harvested after the final ABR assessment for quantification of hair cells.

RESULTS

Noise exposure caused ABR threshold elevations at all frequencies (median 35, 35, 30, 35, and 35 dB SPL, the Noise group; 20, 25, 10, 13, and 20 dB SPL, the Noise + H₂ group; P < .05) but significantly less so in the Noise + H₂ group (P < .05). Outer hair cell (OHC) loss was in the apical, mid, and basal regions 8.8%, 53%, and 14% in the Noise group and 3.5%, 22%, and 1.2% in the Noise + H₂ group. The corresponding inner hair cell (IHC) loss was 0.1%, 14%, and 3.5% in the Noise group and 0%, 2.8%, and 0% in the Noise + H₂ group. The difference between the groups was significant in the basal region for OHCs (P = .003) and apical (P = .033) and basal (P = .048) regions for IHCs.

CONCLUSIONS

Acute acoustic trauma can be reduced by H₂ when inhaled immediately after impulse noise exposure.

The Advancement of Gas-Generating Nanoplatforms in Biomedical Fields: Current Frontiers and Future Perspectives

Diverse gases (NO, CO, H₂ S, H₂ , etc.) have been widely applied in the medical intervention of various diseases, including cancer, cardiovascular disease, ischemia-reperfusion injury, bacterial infection, etc., attributing to their inherent biomedical activities. Although many gases have many biomedical activities, their clinical use is still limited due to the rapid and free diffusion behavior of these gases molecules, which may cause potential side effects and/or ineffective treatment. Gas-generating nanoplatforms (GGNs) are effective strategies to address the aforementioned challenges of gas therapy by preventing gas production or release at nonspecific sites, enhancing GGNs accumulation at targeted sites, and controlling gas release in response to exogenous (UV, NIR, US, etc.) or endogenous (H₂ O₂ , GSH, pH, etc.) stimuli at the lesion site, further maintaining gas concentration within the effective range and achieving the purpose of disease treatment. This review comprehensively summarizes the advancements of "state-of-the-art" GGNs in the recent three years, with emphasis on the composition, structure, preparation process, and gas release mechanism of the nanocarriers. Furthermore, the therapeutic effects and limitations of GGNs in preclinical studies using cell/animal models are discussed. Overall, this review enlightens the further development of this field and promotes the clinical transformation of gas therapy.

Long-term and daily use of molecular hydrogen induces reprogramming of liver metabolism in rats by modulating NADP/NADPH redox pathways

Molecular hydrogen (H₂) has emerged as a new therapeutic option in several diseases and is widely adopted by healthy people. However, molecular data to support therapeutic functions attributed to the biological activities of H₂ remain elusive. Here, using transcriptomic and metabolomic approaches coupled with biochemistry and micro-CT technics, we evaluated the effect of long-term (6 months) and daily use of H₂ on liver function. Rats exposed 2 h daily to H₂ either by drinking HRW (H₂ dissolved in H₂O) or by breathing 4% H₂ gas showed reduced lipogenesis and enhanced lipolysis in the liver, which was associated with apparent loss of visceral fat and brown adipose tissue together with a reduced level of serum lipids. Both transcripts and metabolites enriched in H₂-treated rats revealed alteration of amino acid metabolism pathways and activation of purine nucleotides and carbohydrate biosynthesis pathways. Analysis of the interaction network of genes and metabolites and correlation tests revealed that NADP is the central regulator of H₂ induced metabolic alterations in the liver, which was further confirmed by an increase in the level of components of metabolic pathways that require NADP as substrate. Evidence of immune response regulation activity was also observed in response to exposure to H₂. This work is the first to provide metabolomic and transcriptomic data to uncover molecular targets for the effect of prolonged molecular hydrogen treatment on liver metabolism.

Inhalation of Molecular Hydrogen, a Rescue Treatment for Noise-Induced Hearing Loss

Noise exposure is the most important external factor causing acquired hearing loss in humans, and it is strongly associated with the production of reactive oxygen species (ROS) in the cochlea. Several studies reported that the administration of various compounds with antioxidant effects can treat oxidative stress-induced hearing loss. However, traditional systemic drug administration to the human inner ear is problematic and has not been successful in a clinical setting. Thus, there is an urgent need to develop rescue treatment for patients with acute acoustic injuries. Hydrogen gas has antioxidant effects, rapid distribution, and distributes systemically after inhalation.The purpose of this study was to determine the protective efficacy of a single dose of molecular hydrogen (H₂) on cochlear structures. Guinea pigs were divided into six groups and sacrificed immediately after or at 1 or 2 weeks. The animals were exposed to broadband noise for 2 h directly followed by 1-h inhalation of 2% H₂ or room air. Electrophysiological hearing thresholds using frequency-specific auditory brainstem response (ABR) were measured prior to noise exposure and before sacrifice. ABR thresholds were significantly lower in H₂-treated animals at 2 weeks after exposure, with significant preservation of outer hair cells in the entire cochlea. Quantification of synaptophysin immunoreactivity revealed that H₂ inhalation protected the cochlear inner hair cell synaptic structures containing synaptophysin. The inflammatory response was greater in the stria vascularis, showing increased Iba1 due to H₂ inhalation.Repeated administration of H₂ inhalation may further improve the therapeutic effect. This animal model does not reproduce conditions in humans, highlighting the need for additional real-life studies in humans.

Iron deficiency is associated with poor prognosis in idiopathic sudden sensorineural hearing loss

OBJECTIVE

The effects of iron deficiency on the prognosis of idiopathic sudden sensorineural hearing loss are unclear. This study aimed to investigate the association between serum iron levels and idiopathic sudden sensorineural hearing loss prognosis and its usefulness as an independent prognostic marker for idiopathic sudden sensorineural hearing loss.

METHODS

The audiological and haematological data, including hearing recovery and serum iron levels, of 103 patients with idiopathic sudden sensorineural hearing loss evaluated between 2015 and 2018 were retrospectively analysed.

RESULTS

The overall complete recovery rate was 16.5 per cent. Initial higher hearing threshold was associated with poor idiopathic sudden sensorineural hearing loss prognosis. Serum iron levels were significantly higher in the complete recovery group than in the non-complete recovery group (p < 0.05).

CONCLUSION

The possibility of complete recovery from idiopathic sudden sensorineural hearing loss was significantly lower with lower serum iron levels, suggesting that the serum iron level might be a novel prognostic marker for idiopathic sudden sensorineural hearing loss.

Noise-induced hippocampal oxidative imbalance and aminoacidergic neurotransmitters alterations in developing male rats: Influence of enriched environment during adolescence

Living in big cities might involuntarily expose people to high levels of noise causing auditory and/or extra-auditory impairments, including adverse effects on central nervous system (CNS) areas such as the hippocampus. In particular, CNS development is a very complex process that can be altered by environmental stimuli. We have previously shown that noise exposure of developing rats can induce hippocampal-related behavioral alterations. However, noise-induced biochemical alterations had not been studied yet. Thus, the aim of this work was to assess whether early noise exposure can affect rat hippocampal oxidative state and aminoacidergic neurotransmission tone. Additionally, the effectiveness of an enriched environment (EE) as a neuroprotective strategy was evaluated. Male Wistar rats were exposed to different noise schemes at 7 or 15 days after birth. Upon weaning, some animals were transferred to an EE whereas others were kept in standard cages. Short- and long-term measurements were performed to evaluate reactive oxygen species, thioredoxins levels and catalase activity as indicators of hippocampal oxidative status as well as glutamic acid decarboxylase and a subtype of glutamate transporter to evaluate aminoacidergic neurotransmission tone. Results showed noise-induced changes in hippocampal oxidative state and aminoacidergic neurotransmission markers that lasted until adolescence and differed according to the scheme and the age of exposure. Finally, EE housing was effective in preventing some of these changes. These findings suggest that CNS development seems to be sensitive to the effects of stressors such as noise, as well as those of an environmental stimulation, favoring prompt and lasting molecular changes.

Hydrogen: A Novel Option in Human Disease Treatment

H₂ has shown anti-inflammatory and antioxidant ability in many clinical trials, and its application is recommended in the latest Chinese novel coronavirus pneumonia (NCP) treatment guidelines. Clinical experiments have revealed the surprising finding that H₂ gas may protect the lungs and extrapulmonary organs from pathological stimuli in NCP patients. The potential mechanisms underlying the action of H₂ gas are not clear. H₂ gas may regulate the anti-inflammatory and antioxidant activity, mitochondrial energy metabolism, endoplasmic reticulum stress, the immune system, and cell death (apoptosis, autophagy, pyroptosis, ferroptosis, and circadian clock, among others) and has therapeutic potential for many systemic diseases. This paper reviews the basic research and the latest clinical applications of H₂ gas in multiorgan system diseases to establish strategies for the clinical treatment for various diseases.

Ginsenoside Rd Ameliorates Auditory Cortex Injury Associated With Military Aviation Noise-Induced Hearing Loss by Activating SIRT1/PGC-1α Signaling Pathway

Free radicals and oxidative stress play an important role in the pathogenesis of noise-induced hearing loss (NIHL). Some ginseng monomers showed certain therapeutic effects in NIHL by scavenging free radicals. Therefore, we hypothesized that ginsenoside Rd (GSRd) may exert neuroprotective effects after noise-induced auditory system damage through a mechanism involving the SIRT1/PGC-1α signaling pathway. Forty-eight guinea pigs were randomly divided into four equal groups (normal control group, noise group, experimental group that received GSRd dissolved in glycerin through an intraperitoneal injection at a dose of 30 mg/kg body weight from 5 days before noise exposure until the end of the noise exposure period, and experimental control group). Hearing levels were examined by auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE). Hematoxylin-eosin and Nissl staining were used to examine neuron morphology. RT-qPCR and western blotting analysis were used to examine SIRT1/PGC-1α signaling and apoptosis-related genes, including Bax and Bcl-2, in the auditory cortex. Bax and Bcl-2 expression was assessed via immunohistochemistry analysis. Superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) levels were determined using a commercial testing kit. Noise exposure was found to up-regulate ABR threshold and down-regulate DPOAE amplitudes, with prominent morphologic changes and apoptosis of the auditory cortex neurons (p < 0.01). GSRd treatment restored hearing loss and remarkably alleviated morphological changes or apoptosis (p < 0.01), concomitantly increasing Bcl-2 expression and decreasing Bax expression (p < 0.05). Moreover, GSRd increased SOD and GSH-Px levels and decreased MDA levels, which alleviated oxidative stress damage and activated SIRT1/PGC-1α signaling pathway. Taken together, our findings suggest that GSRd ameliorates auditory cortex injury associated with military aviation NIHL by activating the SIRT1/PGC-1α signaling pathway, which can be an attractive pharmacological target for the development of novel drugs for NIHL treatment.

The preparation of dexamethasone sodium phosphate multivesicular liposomes thermosensative hydrogel and its impact on noise-induced hearing loss in the Guinea pigs

OBJECTIVE

The aim of this study is to establish the dexamethasone sodium phosphate multivesicular liposomes thermosensative hydrogel (DEX-MVLs-Gel) drug delivery system and to analyze the pharmacodynamics, pharmacokinetics and safety of DEX-MVLs-Gel as well as to explore whether the prepared DEX-MVLs-Gel can protect the hearing in the guinea pigs following noise exposure.

METHODS

DEX-MVLs formulations were constructed by double emulsion method, and the DEX-MVLs-Gel was prepared after adding P407 and P188 into the DEX-MVLs. A total of 20 adult albino guinea pigs were chosen to establish the animal models with noise-induced hearing loss. After animals were treated with DEX-MVLs-Gel at concentrations of 20, 6 and 2 mg/mL, and 5 mg/mL Dexamethasone Sodium Phosphate (DEX-P) solution, respectively, the hearing function, drug concentration in the peripheral lymph fluid, and hair cell morphology were assessed.

RESULTS

The ABR threshold of the 20 mg/mL DEX-MVLs-Gel treated group at the frequencies of 4, 8, 16 and 24 kHz were measured as 47.5 ± 5.2, 48.3 ± 4.1, 55.8 ± 3.8 and 57.5 5 ± 5.2 dB SPL, respectively. Statistical significances were noted between the 20 mg/mL DEX-MVLs-Gel treated group and control group at each frequency (all P < 0.05), between the 2 mg/mL and 6 mg/mL DEX-MVLs-Gel treated groups at the frequencies of 4 and 8 kHz (both P < 0.05). High Performance Liquid Chromatography (HPLC) demonstrated that the drug concentrations in the peripheral lymph in all groups were gradually decreased on the 1st, 3rd and 7th d after intratympanic injection. Scattered hair cell loss could be observed mainly in the basal and middle turn in the saline administrated group and the 20 mg/mL DEX-MVLs-Gel administration group, and the hair cell loss was not identified in the apical turn.

CONCLUSIONS

A high concentration (20 mg/mL) of DEX-MVLs-Gel exerts significant protective effects upon the guinea pigs with noise-induced hearing loss. The prepared DEX-MVLs-Gel can be effectively maintained in the peripheral lymph fluid of guinea pigs for 3-7 d and MVLs-Gel causes no obvious ototoxicity.

Octave band noise exposure: Laboratory models and otoprotection efforts

With advances in the understanding of mechanisms of noise injury, the past 30 years have brought numerous efforts to identify drugs that prevent noise-induced hearing loss (NIHL). The diverse protocols used across investigations have made comparisons across drugs difficult. A systematic review of the literature by Hammill [(2017). Doctoral thesis, The University of Texas at Austin] identified original reports of chemical interventions to prevent or treat hearing loss caused by noise exposure. An initial search returned 3492 articles. After excluding duplicate articles and articles that did not meet the systematic review inclusion criteria, a total of 213 studies published between 1977 and 2016 remained. Reference information, noise exposure parameters, species, sex, method of NIHL assessment, and pharmaceutical intervention details for these 213 studies were entered into a database. Frequency-specific threshold shifts in control animals (i.e., in the absence of pharmaceutical intervention) are reported here. Specific patterns of hearing loss as a function of species and noise exposure parameters are provided to facilitate the selection of appropriate pre-clinical models. The emphasis of this report is octave band noise exposure, as this is one of the most common exposure protocols across pharmacological otoprotection studies.

Prebiotic effect of fructo-oligosaccharides on the inner ear of DBA/2 J mice with early-onset progressive hearing loss

Nutrition and dietary habits contribute to the onset and progression of sensorineural hearing loss (SNHL). Fructo-oligosaccharides (FOS) are non-digestible oligosaccharides and are known as prebiotics, which enhance short-chain fatty acid (SCFA) production and antioxidant activity. Although a substantial number of studies have shown that FOS play a role in the prevention of lifestyle-related diseases as prebiotics, little is known about the effects on the inner ear. The purpose of this study is to investigate the effect of FOS on gene expression and spiral ganglion neuron (SGN) protection in the inner ear of DBA/2 J mice, which is a model for early-onset progressive hearing loss. DBA/2 J mice were fed either control diet or FOS diet contained 10% (w/w) of FOS for 8 weeks. Analysis of mice fed the FOS diet revealed a change in intestinal flora including an inversion of the ratio of Bacteroidetes and Firmicutes, which was followed by a significant increase in SCFAs in the cecum and a decrease in an oxidative stress marker in the serum. In the inner ear, gene expression of neurotrophin, brain-derived neurotrophic factor (BDNF), its receptor, tyrosine kinase receptor b (Trkb), and the SCFA receptor, free fatty acid receptor 3 (FFAR3), were increased by FOS. In addition, the survival rate of SGNs in the inner ear was maintained in FOS-fed mice. Altogether, these results suggest that a compositional variation of the intestinal flora due to a prebiotic effect may be involved in the progression of SNHL.

An LCMS-based untargeted metabolomics protocol for cochlear perilymph: highlighting metabolic effects of hydrogen gas on the inner ear of noise exposed Guinea pigs

INTRODUCTION

Noise-induced hearing loss (NIHL) is an increasing problem in society and accounts for a third of all cases of acquired hearing loss. NIHL is caused by formation of reactive oxygen species (ROS) in the cochlea causing oxidative stress. Hydrogen gas (H₂) can alleviate the damage caused by oxidative stress and can be easily administered through inhalation.

OBJECTIVES

To present a protocol for untargeted metabolomics of guinea pig perilymph and investigate the effect of H₂ administration on the perilymph metabolome of noise exposed guinea pigs.

METHODS

The left ear of guinea pigs were exposed to hazardous impulse noise only (Noise, n = 10), noise and H₂ (Noise + H2, n = 10), only H₂ (H2, n = 4), or untreated (Control, n = 2). Scala tympani perilymph was sampled from the cochlea of both ears. The polar component of the perilymph metabolome was analyzed using a HILIC-UHPLC-Q-TOF-MS-based untargeted metabolomics protocol. Multivariate data analysis (MVDA) was performed separately for the exposed- and unexposed ear.

RESULTS

MVDA allowed separation of groups Noise and Noise + H2 in both the exposed and unexposed ear and yielded 15 metabolites with differentiating relative abundances. Seven were found in both exposed and unexposed ear data and included two osmoprotectants. Eight metabolites were unique to the unexposed ear and included a number of short-chain acylcarnitines.

CONCLUSIONS

A HILIC-UHPLC-Q-TOF-MS-based protocol for untargeted metabolomics of perilymph is presented and shown to be fit-for-purpose. We found a clear difference in the perilymph metabolome of noise exposed guinea pigs with and without H₂ treatment.

Hydrogen gas improves photothermal therapy of tumor and restrains the relapse of distant dormant tumor

Inflammation during photothermal therapy (PTT) of tumor usually results in adverse consequences. Here, a biomembrane camouflaged nanomedicine (mPDAB) containing polydopamine and ammonia borane was designed to enhance PTT efficacy and mitigate inflammation. Polydopamine, a biocompatible photothermal agent, can effectively convert light into heat for PTT. Ammonia borane was linked to the surface of polydopamine through the interaction of hydrogen bonding, which could destroy redox homoeostasis in tumor cells and reduce inflammation by H₂ release in tumor microenvironment. Owing to the same origin of outer biomembranes, mPDAB showed excellent tumor accumulation and low systemic toxicity in a breast tumor model. Excellent PTT efficacy and inflammation reduction made the mPDAB completely eliminate the primary tumors, while also restraining the outgrowth of distant dormant tumors. The biomimetic nanomedicine shows potentials as a universal inflammation-self-alleviated platform to ameliorate inflammation-related disease treatment, including but not limited to PTT for tumor.

Hydrogen Gas from Inflammation Treatment to Cancer Therapy

Hydrogen (H₂) therapy is a highly promising strategy against several diseases due to its inherent biosafety. However, the current H₂ treatment modalities rely predominantly on the systemic administration of the gas, resulting in poor targeting and utilization. Furthermore, although H₂ has significant anti-tumor effects, the underlying mechanisms have not yet been elucidated. Due to their ultrasmall size, nanomaterials are highly suitable drug-delivery systems with a myriad of biomedical applications. Nanocarrier-mediated H₂ delivery, as well as in situ production of H₂ by nanogenerators, can significantly improve targeted accumulation of the gas and accelerate the therapeutic effects. In addition, nanomaterials can be further modified to enhance passive or active accumulation at the target site. In this Perspective, we summarize the mechanism of H₂ therapy and describe possibilities for combining H₂ therapy with nanomaterials. We also discuss the current challenges of H₂ therapy and provide some insights into this burgeoning field.

Exposure of Developing Male Rats to One or Multiple Noise Sessions and Different Housing Conditions: Hippocampal Thioredoxin Changes and Behavioral Alterations

Exposure of developing rats to noise has shown to induce hippocampal-related behavioral alterations that were prevented after a week of housing in an enriched environment. However, neither the effect of repeated exposures nor its impact on key endogenous antioxidants had been studied yet. Thus, the aim of the present work was to reveal novel data about hippocampal oxidative state through the measurement of possible age-related differences in the levels of hippocampal thioredoxins in rats exposed to noise at different developmental ages and subjected to different schemes and housing conditions. In addition, the possibility that oxidative changes could underlie hippocampal-related behavioral changes was also analyzed. Developing male Wistar rats were exposed to noise for 2 h, either once or for 5 days. Upon weaning, some animals were transferred to an enriched cage for 1 week, whereas others were kept in standard cages. One week later, auditory and behavioral assessments, as well as measurement of hippocampal thioredoxin, were performed. Whereas no changes in the auditory function were observed, significant behavioral differences were found, that varied according to the age, scheme of exposure and housing condition. In addition, a significant increase in Trx-1 levels was found in all noise-exposed groups housed in standard cages. Housing animals in an enriched environment for 1 week was effective in preventing most of these changes. These findings suggest that animals become less susceptible to undergo behavioral alterations after repeated exposure to an environmental challenge, probably due to the ability of adaptation to an unfavorable condition. Moreover, it could be hypothesized that damage to younger individuals could be more easily prevented by a housing manipulation.

Use of Gases to Treat Cochlear Conditions

Although the cochlear vascular supply (stria vascularis) is designed to block to certain compounds and molecules, it must enable gas exchange to survive. The inner ear capillaries must deliver oxygen and remove carbon dioxide for the cochlea to function. These gases diffuse through tissues across a concentration gradient to reach the desired target. Tight junctions or the endothelial basement membrane do not impede them. Therefore, gases that can diffuse into the inner ear are attractive as therapeutic agents. The two gases most often used in this way are oxygen and hydrogen, although carbon dioxide, ozone, and argon have also been investigated. Typically, oxygen is delivered as hyperbaric oxygen (HBO) (oxygen at pressure higher than atmospheric) to provide increased oxygen levels to the inner ear. This not only relieves hypoxia, but also has anti-inflammatory and other biochemical effects. HBO is used clinically to treat idiopathic sudden sensorineural hearing loss, and both animal and human studies suggest it may also assist recovery after acute acoustic trauma. Laboratory studies suggest hydrogen works as a free radical scavenger and reduces the strong oxidants hydroxyl radicals and peroxynitrite. It also has anti-apoptotic effects. Because of its anti-oxidant and anti-inflammatory effects, it has been studied as a treatment for ototoxicity and shows benefit in an animal model of cisplatinum toxicity. Gas diffusion offers an effective way to provide therapy to the inner ear, particularly since some gases (oxygen, hydrogen, carbon dioxide, ozone, argon) have important therapeutic effects for minimizing cochlear damage.

Gas-Generating Nanoplatforms: Material Chemistry, Multifunctionality, and Gas Therapy

The fast advances of theranostic nanomedicine enable the rational design and construction of diverse functional nanoplatforms for versatile biomedical applications, among which gas-generating nanoplatforms (GGNs) have emerged very recently as unique theranostic nanoplatforms for broad gas therapies. Here, the recent developments of the rational design and chemical construction of versatile GGNs for efficient gas therapies by either exogenous physical triggers or endogenous disease-environment responsiveness are reviewed. These gases involve some therapeutic gases that can directly change disease status, such as oxygen (O₂ ), nitric oxide (NO), carbon monoxide (CO), hydrogen (H₂ ), hydrogen sulfide (H₂ S) and sulfur dioxide (SO₂ ), and other gases such as carbon dioxide (CO₂ ), dl-menthol (DLM), and gaseous perfluorocarbon (PFC) for supplementary assistance of the theranostic process. Abundant nanocarriers have been adopted for gas delivery into lesions, including poly(d,l-lactic-co-glycolic acid), micelles, silica/mesoporous silica, organosilica, MnO₂ , graphene, Bi₂ Se₃ , upconversion nanoparticles, CaCO₃ , etc. Especially, these GGNs have been successfully developed for versatile biomedical applications, including diagnostic imaging and therapeutic use. The biosafety issue, challenges faced, and future developments on the rational construction of GGNs are also discussed for further promotion of their clinical translation to benefit patients.

Regional up-regulation of NOX2 contributes to the differential vulnerability of outer hair cells to neomycin

In hearing loss induced by aminoglycoside antibiotics, the outer hair cells (OHCs) in the basal turn are always more susceptible than OHCs in the apical turn, while the underlying mechanisms remain unknown. In this study, we reported that NAPDH oxidase 2 (NOX2) played an important role in the OHCs damage preferentially in the basal turn. Normally, NOX2 was evenly expressed in OHCs among different turns, at a relatively low level. However, after neomycin treatment, NOX2 was dominantly induced in OHCs in the basal turn. In vivo and in vitro studies demonstrated that inhibition of NOX2 significantly alleviated neomycin-induced OHCs damages, as seen from both the cleaved caspase-3 and TUNEL staining. Moreover, gp91 ds-tat delivery and DHE staining results showed that NOX2-derived ROS was responsible for neomycin ototoxicity. Taken together, our study shows that regional up-expression of NOX2 and subsequent increase of ROS in OHCs of the basal turn is an important factor contributing to the vulnerability of OHCs there, which should shed light on the prevention of hearing loss induced by aminoglycoside antibiotics.

The transfer of hydrogen from inert gas to therapeutic gas

Hydrogen is the most abundant chemical element in the universe, and has been used as an inert gas for a long time. More recent studies have shown that molecular hydrogen as a kind of antioxidant, anti-inflammatory, anti-apoptosis, gene expression and signal modulation molecule, can be used for the treatment of many diseases. This review mainly focuses on the research progresses of hydrogen in various medical fields and the possible action mechanisms.

Prevention of ischemia-induced hearing loss by intravenous administration of hydrogen-rich saline in gerbil

OBJECTIVE

Hydrogen-rich water, which is a potent antioxidant agent, was investigated for its protective effects against ischemic damage of the cochlea in gerbils.

METHODS

The animals were subjected to transient cochlear ischemia by occluding the bilateral vertebral arteries for l5min. Five milliliters of hydrogen-rich saline was then intravenously administered immediately after the insult. Saline without hydrogen was used as a control. Effects of hydrogen were evaluated using the auditory brainstem response (ABR) and histological studies of the inner ear.

RESULTS

In non-ischemia animals, ABR thresholds and histological findings of the cochlea did not change by administration of saline or hydrogen-rich saline. In contrast, transient cochlear ischemia caused a 24.2±3.8dB increase in the ABR threshold at 8kHz, and a decrease of 14.1%±1.8% in the number of inner hair cells (IHCs) at the basal turn on day 7. Ischemic damage was more severe at 16 and 32kHz. When the animals were treated with hydrogen-rich saline, cochlear damage was significantly reduced: the increase in ABR threshold was 11.7±2.6dB at 8kHz and the IHC loss was 7.5%±2.1% at the basal turn on day 7. The effects of hydrogen-rich saline were more prominent at higher frequencies.

CONCLUSIONS

Intravenous administration of hydrogen-rich saline was effective in preventing acute hearing loss due to transient cochlear ischemia.

Molecular hydrogen: a preventive and therapeutic medical gas for various diseases

Since the 2007 discovery that molecular hydrogen (H2) has selective antioxidant properties, multiple studies have shown that H2 has beneficial effects in diverse animal models and human disease. This review discusses H2 biological effects and potential mechanisms of action in various diseases, including metabolic syndrome, organ injury, and cancer; describes effective H2 delivery approaches; and summarizes recent progress toward H2 applications in human medicine. We also discuss remaining questions in H2 therapy, and conclude with an appeal for a greater role for H2 in the prevention and treatment of human ailments that are currently major global health burdens. This review makes a case for supporting hydrogen medicine in human disease prevention and therapy.

Molecular mechanisms underlying the protective effects of hydrogen-saturated saline on noise-induced hearing loss

OBJECTIVES

This study aimed to explore the molecular mechanism of the protective effects of hydrogen-saturated saline on NIHL.

METHODS

Guinea pigs were divided into three groups: hydrogen-saturated saline; normal saline; and control. For saline administration, the guinea pigs were given daily abdominal injections 3 d before and 1 h before noise exposure. ABR were tested to examine cochlear physiology changes. The changes of 8-hydroxy-desoxyguanosine (8-HOdG), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), intercellular cell adhesion molecule-1 (ICAM-1) and high mobility group box-1 protein (HMGB1) in the cochlea were also examined.

RESULTS

The results showed that pre-treatment with hydrogen-saturated saline could significantly attenuate noise-induced hearing loss. The concentration of 8-HOdG was also significantly decreased in the hydrogen-saturated saline group compared with the normal saline group. After noise exposure, the concentrations of IL-1, IL-6, TNF-α, and ICAM-1 in the cochlea of guinea pigs in the hydrogen-saturated saline group were dramatically reduced compared to those in the normal saline group. The concentrations of HMGB-1 and IL-10 in the hydrogen-saturated saline group were significantly higher than in those in the normal saline group immediately and at 7 d after noise exposure.

CONCLUSIONS

This study revealed for the first time the protective effects of hydrogen-saturated saline on noise-induced hearing loss (NIHL) are related to both the anti-oxidative activity and anti-inflammatory activity.

Hydrogen Inhalation Protects against Ototoxicity Induced by Intravenous Cisplatin in the Guinea Pig

Introduction: Permanent hearing loss and tinnitus as side-effects from treatment with the anticancer drug cisplatin is a clinical problem. Ototoxicity may be reduced by co-administration of an otoprotective agent, but the results in humans have so far been modest. Aim: The present preclinical in vivo study aimed to explore the protective efficacy of hydrogen (H₂) inhalation on ototoxicity induced by intravenous cisplatin. Materials and Methods: Albino guinea pigs were divided into four groups. The Cispt (n = 11) and Cispt+H₂ (n = 11) groups were given intravenous cisplatin (8 mg/kg b.w., injection rate 0.2 ml/min). Immediately after, the Cispt+H₂ group also received gaseous H₂ (2% in air, 60 min). The H₂ group (n = 5) received only H₂ and the Control group (n = 7) received neither cisplatin nor H₂. Ototoxicity was assessed by measuring frequency specific ABR thresholds before and 96 h after treatment, loss of inner (IHCs) and outer (OHCs) hair cells, and by performing densitometry-based immunohistochemistry analysis of cochlear synaptophysin, organic transporter 2 (OCT2), and copper transporter 1 (CTR1) at 12 and 7 mm from the round window. By utilizing metabolomics analysis of perilymph the change of metabolites in the perilymph was assessed. Results: Cisplatin induced electrophysiological threshold shifts, hair cell loss, and reduced synaptophysin immunoreactivity in the synapse area around the IHCs and OHCs. H₂ inhalation mitigated all these effects. Cisplatin also reduced the OCT2 intensity in the inner and outer pillar cells and in the stria vascularis as well as the CTR1 intensity in the synapse area around the IHCs, the Deiters' cells, and the stria vascularis. H₂ prevented the majority of these effects. Conclusion: H₂ inhalation can reduce cisplatin-induced ototoxicity on functional, cellular, and subcellular levels. It is proposed that synaptopathy may serve as a marker for cisplatin ototoxicity. The effect of H₂ on the antineoplastic activity of cisplatin needs to be further explored.

Photobiomodulation rescues the cochlea from noise-induced hearing loss via upregulating nuclear factor κB expression in rats

Photobiomodulation (PBM) is a noninvasive treatment that can be neuroprotective, although the underlying mechanisms remain unclear. In the present study, we assessed the mechanism of PBM as a novel treatment for noise-induced hearing loss, focusing on the nuclear factor (NF)-κB signaling pathway. Sprague-Dawley rats were exposed to 1-octave band noise centered at 4kHz for 5h (121dB). After noise exposure, their right ears were irradiated with an 808nm diode laser beam at an output power density of 165mW/cm(2) for 30min a day for 5 consecutive days. Measurement of the auditory brainstem response revealed an accelerated recovery of auditory function in the groups treated with PBM compared with the non-treatment group at 4, 7, and 14 days after noise exposure. Immunofluorescent image analysis for inducible nitric oxide synthase and cleaved caspase-3 showed lesser immunoreactivities in outer hair cells in the PBM group compared with the non-treatment group. However, immunofluorescent image analysis for NF-κB, an upstream protein of inducible nitric oxide synthase, revealed greater activation in the PBM group compared with the naïve and non-treatment groups. Western blot analysis for NF-κB also showed stronger activation in the cochlear tissues in the PBM group compared with the naïve and non-treatment groups (p<0.01, each). These data suggest that PBM activates NF-κB to induce protection against inducible nitric oxide synthase-triggered oxidative stress and caspase-3-mediated apoptosis that occur following noise-induced hearing loss.

PON2 and ATP2B2 gene polymorphisms with noise-induced hearing loss

BACKGROUND

Noise-induced hearing loss (NIHL) is a complex disease induced by a combination of genetic and environmental factors. Paraoxonase2 (PON2) gene involved in the regulation of reactive oxygen species, and affecting the vulnerability of cochlea to NIHL, and ATPase, calcium-transporting, plasma membrane 2 (ATP2B2) gene which encodes plasma membrane calcium-transporting ATPase isoform 2 (PMCA2) are the candidate genes relating to the attack of NIHL. In this study, we investigated whether ATP2B2 and PON2 polymorphisms were associated with NIHL in Chinese of Han nationality population.

METHODS

We performed a case-control study between six single nucleotide polymorphisms (SNPs) (rs1719571, rs3209637 and rs4327369 within ATP2B2, rs12026, rs7785846 and rs12704796 within PON2) and NIHL in 454 subjects. All the SNPs were genotypes, using the TaqMan MGB probe assay. Odds ratios (ORs) were calculated with 95% confidence intervals (95% CIs) with logistic regression analysis to test the level of association for SNPs.

RESULTS

In our study, 221 subjects with hearing loss and 233 subjects without hearing loss were recruited. The frequencies of the CG and CG + GG genotype of rs12026 (PON2) conferred risk factors for NIHL with adjusted OR values of 2.62 (95% CI, 1.69-4.06) and 2.48 (95% CI, 1.63-3.78), respectively. This kind of significance was also found at locus rs7785846, where genotypes CT and CT + TT were the risk types, with adjusted ORs of 2.52 (95% CI, 1.62-3.93) and 2.35 (95% CI, 1.54-3.58), respectively. We performed stratified analysis per noise exposure level, when it came to rs7785846 and rs12026 in the >92 dB(A) noise exposure group, the subjects who carried heterozygote were of significantly (P<0.01) higher susceptibility to NIHL than homozygote carriers. By contrast, no significantly higher risk was found for any rs12704796 genotypes or any genotypes in ATP2B2 (P>0.05), which may suggest that these SNPs did not have significant effects on noise susceptibility across noise exposure.

CONCLUSIONS

Our research suggested that PON2 might play a role in the etiology of NIHL in Chinese of Han nationality population.

Noise exposure and oxidative balance in auditory and extra-auditory structures in adult and developing animals. Pharmacological approaches aimed to minimize its effects

Noise coming from urban traffic, household appliances or discotheques might be as hazardous to the health of exposed people as occupational noise, because may likewise cause hearing loss, changes in hormonal, cardiovascular and immune systems and behavioral alterations. Besides, noise can affect sleep, work performance and productivity as well as communication skills. Moreover, exposure to noise can trigger an oxidative imbalance between reactive oxygen species (ROS) and the activity of antioxidant enzymes in different structures, which can contribute to tissue damage. In this review we systematized the information from reports concerning noise effects on cell oxidative balance in different tissues, focusing on auditory and non-auditory structures. We paid specific attention to in vivo studies, including results obtained in adult and developing subjects. Finally, we discussed the pharmacological strategies tested by different authors aimed to minimize the damaging effects of noise on living beings.

Beneficial biological effects and the underlying mechanisms of molecular hydrogen - comprehensive review of 321 original articles

Therapeutic effects of molecular hydrogen for a wide range of disease models and human diseases have been investigated since 2007. A total of 321 original articles have been published from 2007 to June 2015. Most studies have been conducted in Japan, China, and the USA. About three-quarters of the articles show the effects in mice and rats. The number of clinical trials is increasing every year. In most diseases, the effect of hydrogen has been reported with hydrogen water or hydrogen gas, which was followed by confirmation of the effect with hydrogen-rich saline. Hydrogen water is mostly given ad libitum. Hydrogen gas of less than 4 % is given by inhalation. The effects have been reported in essentially all organs covering 31 disease categories that can be subdivided into 166 disease models, human diseases, treatment-associated pathologies, and pathophysiological conditions of plants with a predominance of oxidative stress-mediated diseases and inflammatory diseases. Specific extinctions of hydroxyl radical and peroxynitrite were initially presented, but the radical-scavenging effect of hydrogen cannot be held solely accountable for its drastic effects. We and others have shown that the effects can be mediated by modulating activities and expressions of various molecules such as Lyn, ERK, p38, JNK, ASK1, Akt, GTP-Rac1, iNOS, Nox1, NF-κB p65, IκBα, STAT3, NFATc1, c-Fos, and ghrelin. Master regulator(s) that drive these modifications, however, remain to be elucidated and are currently being extensively investigated.

Effects of hydrogen-rich saline on early acute kidney injury in severely burned rats by suppressing oxidative stress induced apoptosis and inflammation

Background

Early acute kidney injury (AKI) in severely burned patients predicts a high mortality that is multi-factorial. Hydrogen has been reported to alleviate organ injury via selective quenching of reactive oxygen species. This study investigated the potential protective effects of hydrogen against severe burn-induced early AKI in rats.

Methods

Severe burn were induced via immersing the shaved back of rats into a 100°C bath for 15 s. Fifty-six Sprague–Dawley rats were randomly divided into Sham, Burn + saline, and Burn + hydrogen-rich saline (HS) groups, and renal function and the apoptotic index were measured. Kidney histopathology and immunofluorescence staining, quantitative real-time PCR, ELISA and western blotting were performed on the sera or renal tissues of burned rats to explore the underlying effects and mechanisms at varying time points post burn.

Results

Renal function and tubular apoptosis were improved by HS treatment. In addition, the oxidation–reduction potential and malondialdehyde levels were markedly reduced with HS treatment, whereas endogenous antioxidant enzyme activities were significantly increased. HS also decreased the myeloperoxidase levels and influenced the release of inflammatory mediators in the sera and renal tissues of the burned rats. The regulatory effects of HS included the inhibition of p38, JNK, ERK and NF-κB activation, and an increase in Akt phosphorylation.

Conclusion

Hydrogen can attenuate severe burn-induced early AKI; the mechanisms of protection include the inhibition of oxidative stress induced apoptosis and inflammation, which may be mediated by regulation of the MAPKs, Akt and NF-κB signalling pathways.