Molecular hydrogen as a novel antioxidant: overview of the advantages of hydrogen for medical applications

Molecular Hydrogen Therapy: Mechanisms, Delivery Methods, Preventive, and Therapeutic Application

Molecular hydrogen (H2), recognized as the smallest gas molecule, is capable of permeating cellular membranes and diffusing throughout the body. Due to its high bioavailability, H2 is considered a therapeutic gas for the treatment of various diseases. The therapeutic efficacy of hydrogen is contingent upon factors such as the administration method, duration of contact with diseased tissue, and concentration at targeted sites. H2 can be administered exogenously and is also produced endogenously within the intestinal tract. A comprehensive understanding of its delivery mechanisms and modes of action is crucial for advancing hydrogen medicine. This review highlights H₂'s mechanisms of action, summarizes its administration methods, and explores advancements in treating intestinal diseases (e.g., inflammatory bowel disease, intestinal ischemia-reperfusion, colorectal cancer). Additionally, its applications in managing other diseases are discussed. Finally, the challenges associated with its clinical application and potential solutions are explored. We propose that current delivery challenges faced by H2 can be effectively addressed through the use of nanoplatforms; furthermore, interactions between hydrogen and gut microbiota may provide insights into its mechanisms for treating intestinal diseases. Future research should explore the synergistic effects of H2 in conjunction with conventional therapies and develop personalized treatment plans to achieve precision medicine.

A novel Si-based antioxidant agent attenuates antibody-mediated rejection in allogeneic rat kidney transplantation

Antibody-mediated rejection remains a leading cause of graft loss during kidney transplantation. Ischemia reperfusion injury (IRI) has been reported to promote T cell proliferation, leading to B cell activation and subsequent production of donor-specific antibodies, which target antigens on the vascular endothelium. We hypothesize that a novel therapeutic strategy targeting highly toxic reactive oxygen species could mitigate oxidative stress and immune responses associated with IRI. Our previous study demonstrated that oral administration of a silicon (Si)-based agent consistently generates substantial amounts of hydrogen, effectively suppressing IRI-induced oxidative stress and acute kidney injury in a rat renal clamp model. Here, we investigated the effect of the Si-based agent on immune responses in an allogeneic kidney transplant setting. Using both short-term and long-term evaluation models, we found that the Si-based agent suppressed oxidative stress and acquired immunity activation. Furthermore, early suppression of donor-specific antibody production and amelioration of chronic antibody-mediated rejection were observed. These findings indicate that the Si-based agent offers protective effects on graft function and survival, highlighting its potential clinical application to improve outcomes for kidney transplant recipients.

Protective effect of hydrogen-rich water on spermatogenesis in high-fat diet obese rats

Obesity can impair spermatogenesis by various mechanisms such as decreased sperm concentration and increased oxidative DNA damage. Hydrogen-rich water (HRW) possesses therapeutic antioxidant properties that may help offer protection to sperm. This study aimed to investigate the therapeutic potential of HRW on spermatogenesis dysfunction in rats with high-fat diet (HFD)-induced obesity. In this experiment, thirty male Wistar Albino rats were divided into three groups. 1) Control group: fed a normal diet, 2) Obese group: fed a HFD (45 % fat), and 3) HFD + HRW group: fed a high-fat diet and received HRW. HRW (1.5 mM) was administered orally every day. After 16 weeks, blood and tissue samples (testis and epididymis) were collected for biochemical and histopathological analysis. Serum LH, FSH and testosterone and oxidative and antioxidative markers, malondialdehyde (MDA), superoxide dismutase (SOD), and total thiol groups were measured in testis and epididymal tissues. The results showed that the HFD significantly increased food intake, body weight, and lee index, all of which were reduced in the HRW-treated obese group. Testis weight, sperm count, Serum LH and histological evaluation of testis including Sertoli and spermatogonia cell counts were significantly lower in the obese group but improved with HRW treatment. Additionally, HRW treatment increased the luminal diameter of seminiferous tubules, epididymal epithelia height, tissue SOD, and total thiol levels, while reducing MDA level in the testis. This study showed that administration of HRW can improve spermatogenesis in obese animals by reducing oxidative stress and ameliorating histological changes in the testis and epididymis, suggesting its potential benefits in combating high-fat diet-induced reproductive dysfunction.

Antioxidant Therapies as Emerging Adjuncts in Rheumatoid Arthritis: Targeting Oxidative Stress to Enhance Treatment Outcomes

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by persistent inflammation and progressive joint destruction. Recent data underscore oxidative stress as a primary factor in the pathophysiology of rheumatoid arthritis, intensifying inflammatory processes and tissue damage via the overproduction of reactive oxygen species (ROS) and compromised antioxidant defenses. Current therapies, including disease-modifying antirheumatic drugs (DMARDs), primarily target immune dysregulation but fail to address oxidative stress, necessitating novel adjunctive treatment strategies. This review explores the potential of antioxidant-based therapies as complementary approaches to RA management. Natural compounds such as curcumin, resveratrol, sulforaphane, and propolis exhibit strong anti-inflammatory and antioxidative properties by modulating redox-sensitive pathways, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and nuclear factor erythroid 2-related factor 2(Nrf2)/heme oxygenase (HO-1). N-acetylcysteine (NAC) replenishes intracellular glutathione, enhancing cellular resilience against oxidative stress. Additionally, molecular hydrogen (H2) selectively neutralizes harmful ROS, reducing oxidative damage and inflammation. The role of vitamin supplementation (D, B12, C, and K) in regulating immune responses and protecting joint structures is also discussed. This review aims to evaluate the efficacy and potential clinical applications of antioxidant therapies in RA, emphasizing their role in mitigating oxidative damage and improving treatment outcomes. While preliminary findings are promising, further clinical trials are needed to establish standardized dosing, long-term safety, and their integration into current RA treatment protocols.

A comprehensive review of molecular hydrogen as a novel nutrition therapy in relieving oxidative stress and diseases: Mechanisms and perspectives

Oxidative stress is responsible for the pathogenesis of many diseases, and antioxidants are commonly included in their treatment protocols. Over the past two decades, numerous biomedical reports have revealed the therapeutic benefits of molecular hydrogen (H2) in relieving oxidation-related diseases. H2 has been found to have selective antioxidant properties against the most dangerous oxidants (hydroxyl radicals and peroxynitrite). H2 demonstrates numerous biologically therapeutic properties, including anti-inflammatory, antioxidant, anti-cancer, anti-stress, anti-apoptotic, anti-allergic effects, signaling molecule functions, regulation of redox balance, modulation of antioxidant enzyme gene expression, improvement of blood vessel function, down-regulation of pro-inflammatory cytokines, stimulation of energy metabolism, and protection of the nervous system. Experimental and clinical studies have shown the potential use of hydrogen nutrition therapy for ameliorating various diseases, including cardiovascular, respiratory, and metabolic disorders, as well as obesity, gastrointestinal disorders, and brain and nervous system disorders. The administration methods of hydrogen include inhalation, hydrogen-rich water, hydrogen-rich saline, hydrogen-rich eye drops, and hydrogen-rich bathing. Hydrogen nutritional therapy can be applied to different diseases, and it offers a natural alternative to chemical and radiation therapies. This review covers the different administration methods and the latest experimental and clinical research on the potential applications of H2 in nutritional therapy for different diseases.

New possibilities of the prevention and treatment of cardiovascular pathologies. the potential of molecular hydrogen in the reduction of oxidative stress and its consequences

Disproportion between reactive oxygen species (ROS) production and the body's antioxidant system can cause oxidative stress, which is considered a common denominator in various pathological conditions, including cardiovascular diseases, aging, and cognitive disorders. The generation of free radicals, which occurs through partial reduction of oxygen, can quickly overwhelm the endogenous antioxidant system capacity of the cell. This causes lipid, protein, DNA and RNA damage, inflammation, and overall cell degeneration, which can be mitigated by various antioxidants. However, their use in human medicine did not bring the expected effect. Molecular hydrogen (H2), due to its unique physical and chemical properties, provides a number of benefits for alleviating oxidative stress. H2 is superior to conventional antioxidants as it can selectively reduce (.)OH radicals while preserving important ROS that are otherwise used for normal cell signaling. Key words Oxidative stress, Cardiovascular diseases, Molecular hydrogen, ROS, Inflammation.

The Role of Mast Cells in the Remodeling Effects of Molecular Hydrogen on the Lung Local Tissue Microenvironment under Simulated Pulmonary Hypertension

Molecular hydrogen (H2) has antioxidant, anti-inflammatory, and anti-fibrotic effects. In a rat model simulating pulmonary fibrotic changes induced by monocrotaline-induced pulmonary hypertension (MPH), we had previously explored the impact of inhaled H2 on lung inflammation and blood pressure. In this study, we further focused the biological effects of H2 on mast cells (MCs) and the parameters of the fibrotic phenotype of the local tissue microenvironment. MPH resulted in a significantly increased number of MCs in both the pneumatic and respiratory parts of the lungs, an increased number of tryptase-positive MCs with increased expression of TGF-β, activated interaction with immunocompetent cells (macrophages and plasma cells) and fibroblasts, and increased MC colocalization with a fibrous component of the extracellular matrix of connective tissue. The alteration in the properties of the MC population occurred together with intensified collagen fibrillogenesis and an increase in the integral volume of collagen and elastic fibers of the extracellular matrix of the pulmonary connective tissue. The exposure of H2 together with monocrotaline (MCT), despite individual differences between animals, tended to decrease the intrapulmonary MC population and the severity of the fibrotic phenotype of the local tissue microenvironment compared to changes in animals exposed to the MCT effect alone. In addition, the activity of collagen fibrillogenesis associated with MCs and the expression of TGF-β and tryptase in MCs decreased, accompanied by a reduction in the absolute and relative content of reticular and elastic fibers in the lung stroma. Thus, with MCT exposure, inhaled H2 has antifibrotic effects involving MCs in the lungs of rats. This reveals the unknown development mechanisms of the biological effects of H2 on the remodeling features of the extracellular matrix under inflammatory background conditions of the tissue microenvironment.

Hydrogen-Rich Water to Enhance Exercise Performance: A Review of Effects and Mechanisms

Background: Hydrogen-rich water (HRW) has garnered significant interest within the sports and exercise science community due to its selective antioxidant properties. Despite its potential benefits, comprehensive reviews specifically addressing its effects on athletic performance are limited. This review aims to assess the impact of HRW on sports performance and explore the underlying molecular biological mechanisms, with the goal of elucidating how HRW might enhance athletic performance. Methods: This review synthesizes research on HRW by examining articles published between 1980 and April 2024 in databases such as PubMed, the Cochrane Library, Embase, Scopus, and Web of Science. Results: It highlights HRW's effects on various aspects of athletic performance, including endurance, strength, sprint times, lunge movements, countermovement jump height, and time to exhaustion. While the precise mechanisms by which HRW affects athletic performance remain unclear, this review investigates its general molecular biological mechanisms beyond the specific context of sports. This provides a theoretical foundation for future research aimed at understanding how HRW can enhance athletic performance. HRW targets the harmful reactive oxygen and nitrogen species produced during intense exercise, thereby reducing oxidative stress-a critical factor in muscle fatigue, inflammation, and diminished athletic performance. HRW helps to scavenge hydroxyl radicals and peroxynitrite, regulate antioxidant enzymes, mitigate lipid peroxidation, reduce inflammation, protect against mitochondrial dysfunction, and modulate cellular signaling pathways. Conclusions: In summary, while a few studies have indicated that HRW may not produce significant beneficial effects, the majority of research supports the conclusion that HRW may enhance athletic performance across various sports. The potential mechanisms underlying these benefits are thought to involve HRW's role as a selective antioxidant, its impact on oxidative stress, and its regulation of redox homeostasis. However, the specific molecular biological mechanisms through which HRW improves athletic performance remain to be fully elucidated.

Inhalation of hydrogen gas mitigates sevoflurane-induced neuronal apoptosis in the neonatal cortex and is associated with changes in protein phosphorylation

Inhalation of hydrogen (H2) gas is therapeutically effective for cerebrovascular diseases, neurodegenerative disorders, and neonatal brain disorders including pathologies induced by anesthetic gases. To understand the mechanisms underlying the protective effects of H2 on the brain, we investigated the molecular signals affected by H2 in sevoflurane-induced neuronal cell death. We confirmed that neural progenitor cells are susceptible to sevoflurane and undergo apoptosis in the retrosplenial cortex of neonatal mice. Co-administration of 1-8% H2 gas for 3 h to sevoflurane-exposed pups suppressed elevated caspase-3-mediated apoptotic cell death and concomitantly decreased c-Jun phosphorylation and activation of the c-Jun pathway, all of which are induced by oxidative stress. Anesthesia-induced increases in lipid peroxidation and oxidative DNA damage were alleviated by H2 inhalation. Phosphoproteome analysis revealed enriched clusters of differentially phosphorylated proteins in the sevoflurane-exposed neonatal brain that included proteins involved in neuronal development and synaptic signaling. H2 inhalation modified cellular transport pathways that depend on hyperphosphorylated proteins including microtubule-associated protein family. These modifications may be involved in the protective mechanisms of H2 against sevoflurane-induced neuronal cell death.

Molecular Hydrogen and Extracorporeal Gas Exchange: A Match Made in Heaven? An In Vitro Pilot Study

Extracorporeal circulation (ECC) is frequently implemented in a vast array of modalities such as hemodialysis, cardiopulmonary bypass, extracorporeal membrane oxygenation (ECMO), and others. Patients receiving any such therapy are frequently encumbered with chronic inflammation, which is inherently accompanied by oxidative stress. However, ECC treatments themselves are also responsible for sustaining or promoting inflammation. On these grounds, an in vitro study was designed to investigate the therapeutic potential of molecular hydrogen (H2) against pro-inflammatory agents in ECC settings. Five miniature ECMO circuits and a small vial (Control) were primed with heparinized blood from healthy adult donors (n = 7). Three of the ECMO systems were injected with lipopolysaccharide (LPS), out of which one was additionally treated with an H2 gas mixture. After 6 h, samples were drawn for the assessment of specific biomarkers (MCP-1, MPO, MDA-a, TRX1, and IL-6). Preliminary results indicate a progressive oxidative and inflammatory response between the six systems. Circulation has triggered inflammation and blood trauma, but the staggering influence of LPS in this outcome is indisputable. Accordingly, hydrogen's remedial potential becomes immediately apparent as biomarker concentrations tend to be lower in the H2-handled circuit. Future research should have distinct objectives (e.g., dosage/duration/cycle of hydrogen administration) in order to ascertain the optimal protocol for patient treatment.

Hydrogen Attenuates Cognitive Impairment in Rat Models of Vascular Dementia by Inhibiting Oxidative Stress and NLRP3 Inflammasome Activation

Vascular dementia (VaD) is the second most common form of dementia worldwide. Oxidative stress and neuroinflammation are important factors contributing to cognitive dysfunction in patients with VaD. The antioxidant and anti-inflammatory properties of hydrogen are increasingly being utilized in neurological disorders, but conventional hydrogen delivery has the disadvantage of inefficiency. Therefore, magnesium silicide nanosheets (MSNs) are used to release hydrogen in vivo in larger quantities and for longer periods of time to explore the appropriate dosage and regimen. In this study, it is observed that hydrogen improved learning and working memory in VaD rats in the Morris water maze and Y-maze, which elicits improved cognitive function. Nissl staining of neurons shows that hydrogen treatment significantly improves edema in neuronal cells. The expression and activation of reactive oxygen species (ROS), Thioredoxin-interacting protein (TXNIP), NOD-like receptor protein 3 (NLRP3), caspase-1, and IL-1β in the hippocampus are measured via ELISA, Western blotting, real-time qPCR, and immunofluorescence. The results show that oxidative stress indicators and inflammasome-related factors are significantly decreased after 7dMSN treatment. Therefore, it is concluded that hydrogen can ameliorate neurological damage and cognitive dysfunction in VaD rats by inhibiting ROS/NLRP3/IL-1β-related oxidative stress and inflammation.

Molecular Hydrogen for Outpatients with COVID-19 (Hydro-COVID): A Phase 3 Randomised, Triple-Blinded, Pragmatic, Placebo-Controlled, Multicentre Trial

Background. Due to its antioxidant, anti-inflammatory, anti-apoptosis, and anti-fatigue properties, molecular hydrogen (H2) is potentially a novel therapeutic nutrient for patients with coronavirus acute disease 2019 (COVID-19). We determined the efficacy and safety profile of hydrogen-rich water (HRW) to reduce the risk of COVID-19 progression. Methods: We also conducted a phase 3, triple-blind, randomised, placebo-controlled trial to evaluate treatment with HRW initiated within 5 days after the onset of signs or symptoms in primary care patients with mild-to-moderate, laboratory-confirmed COVID-19. Participants were randomised to receive HRW or placebo twice daily for 21 days. The incidence of clinical worsening and adverse events were the primary endpoints. Results: A total of 675 participants were followed up to day 30. HRW was not superior to placebo in preventing clinical worsening at day 14: in H2 group, 46.1% in the H2 group, 43.5% in the placebo group, hazard ratio 1.09, 90% confidence interval [0.90-1.31]. One death was reported at day 30 in the H2 group and two in the placebo group at day 30. Adverse events were reported in 91 (27%) and 89 (26.2%) participants, respectively. Conclusions: HRW taken twice daily from the onset of COVID-19 symptoms for 21 days did not reduce clinical worsening.

The Protective Role of Molecular Hydrogen in Ischemia/Reperfusion Injury

Ischemia/reperfusion injury (IRI) represents a significant contributor to morbidity and mortality associated with various clinical conditions, including acute coronary syndrome, stroke, and organ transplantation. During ischemia, a profound hypoxic insult develops, resulting in cellular dysfunction and tissue damage. Paradoxically, reperfusion can exacerbate this injury through the generation of reactive oxygen species and the induction of inflammatory cascades. The extensive clinical sequelae of IRI necessitate the development of therapeutic strategies to mitigate its deleterious effects. This has become a cornerstone of ongoing research efforts in both basic and translational science. This review examines the use of molecular hydrogen for IRI in different organs and explores the underlying mechanisms of its action. Molecular hydrogen is a selective antioxidant with anti-inflammatory, cytoprotective, and signal-modulatory properties. It has been shown to be effective at mitigating IRI in different models, including heart failure, cerebral stroke, transplantation, and surgical interventions. Hydrogen reduces IRI via different mechanisms, like the suppression of oxidative stress and inflammation, the enhancement of ATP production, decreasing calcium overload, regulating cell death, etc. Further research is still needed to integrate the use of molecular hydrogen into clinical practice.

Effects of combined treatment with hydrogen-rich electrolyzed water and tea polyphenols on oxidative stress, intestinal injury and intestinal flora disruption in heat-stressed mice

Heat stress (HS) can cause damage to the organism, especially the intestinal tract. In this paper, we investigated the effects of the combined action of tea polyphenols (TP) and hydrogen-rich electrolyzed water (HRW) on HS in mice. The combination of HRW feeding and TP of intraperitoneal injection was screened by in vitro antioxidant activity assay. The results revealed that the combined treatment was more helpful in alleviating the effects of HS on the behavior, growth performance, oxidative damage, and intestinal tract of mice compared with the respective treatments of TP and HRW (P < 0.05). Additionally, the combined treatment could repair HS-induced intestinal dysbiosis in mice, augmenting the number and abundance of bacteria, increasing the number of beneficial genera (Lachnospiraceae_NK4A136_group and Lactobacillus), and decreasing the number of harmful genera (Desulfovibrio and Enterorhabdus), and the effect was significantly better than that of individual treatment (P < 0.05). In conclusion, the combined treatment of TP and HRW effectively mitigates the adverse effects of HS on mouse behavior, growth performance, oxidative damage, and intestinal dysbiosis, surpassing the efficacy of individual treatments with TP or HRW alone.

Hydrogen production, storage, and transportation: recent advances

One such technology is hydrogen-based which utilizes hydrogen to generate energy without emission of greenhouse gases. The advantage of such technology is the fact that the only by-product is water. Efficient storage is crucial for the practical application of hydrogen. There are several techniques to store hydrogen, each with certain advantages and disadvantages. In gaseous hydrogen storage, hydrogen gas is compressed and stored at high pressures, requiring robust and expensive pressure vessels. In liquid hydrogen storage, hydrogen is cooled to extremely low temperatures and stored as a liquid, which is energy-intensive. Researchers are exploring advanced materials for hydrogen storage, including metal hydrides, carbon-based materials, metal-organic frameworks (MOFs), and nanomaterials. These materials aim to enhance storage capacity, kinetics, and safety. The hydrogen economy envisions hydrogen as a clean energy carrier, utilized in various sectors like transportation, industry, and power generation. It can contribute to decarbonizing sectors that are challenging to electrify directly. Hydrogen can play a role in a circular economy by facilitating energy storage, supporting intermittent renewable sources, and enabling the production of synthetic fuels and chemicals. The circular economy concept promotes the recycling and reuse of materials, aligning with sustainable development goals. Hydrogen availability depends on the method of production. While it is abundant in nature, obtaining it in a clean and sustainable manner is crucial. The efficiency of hydrogen production and utilization varies among methods, with electrolysis being a cleaner but less efficient process compared to other conventional methods. Chemisorption and physisorption methods aim to enhance storage capacity and control the release of hydrogen. There are various viable options that are being explored to solve these challenges, with one option being the use of a multilayer film of advanced metals. This work provides an overview of hydrogen economy as a green and sustainable energy system for the foreseeable future, hydrogen production methods, hydrogen storage systems and mechanisms including their advantages and disadvantages, and the promising storage system for the future. In summary, hydrogen holds great promise as a clean energy carrier, and ongoing research and technological advancements are addressing challenges related to production, storage, and utilization, bringing us closer to a sustainable hydrogen economy.

H2 supplied via ammonia borane stimulates lateral root branching via phytomelatonin signaling

A reliable and stable hydrogen gas (H2) supply will benefit agricultural laboratory and field trials. Here, we assessed ammonia borane (AB), an efficient hydrogen storage material used in the energy industry, and determined its effect on plant physiology and the corresponding mechanism. Through hydroponics and pot experiments, we discovered that AB increases tomato (Solanum lycopersicum) lateral root (LR) branching and this function depended on the increased endogenous H2 level caused by the sustainable H2 supply. In particular, AB might trigger LR primordia initiation. Transgenic tomato and Arabidopsis (Arabidopsis thaliana) expressing hydrogenase1 (CrHYD1) from Chlamydomonas reinhardtii not only accumulated higher endogenous H2 and phytomelatonin levels but also displayed pronounced LR branching. These endogenous H2 responses achieved by AB or genetic manipulation were sensitive to the pharmacological removal of phytomelatonin, indicating the downstream role of phytomelatonin in endogenous H2 control of LR formation. Consistently, extra H2 supply failed to influence the LR defective phenotypes in phytomelatonin synthetic mutants. Molecular evidence showed that the phytomelatonin-regulated auxin signaling network and cell-cycle regulation were associated with the AB/H2 control of LR branching. Also, AB and melatonin had little effect on LR branching in the presence of auxin synthetic inhibitors. Collectively, our integrated approaches show that supplying H2 via AB increases LR branching via phytomelatonin signaling. This finding might open the way for applying hydrogen storage materials to horticultural production.

Mitochondria: one of the vital hubs for molecular hydrogen's biological functions

As a novel antioxidant, a growing body of studies has documented the diverse biological effects of molecular hydrogen (H2) in a wide range of organisms, spanning animals, plants, and microorganisms. Although several possible mechanisms have been proposed, they cannot fully explain the extensive biological effects of H2. Mitochondria, known for ATP production, also play crucial roles in diverse cellular functions, including Ca2+ signaling, regulation of reactive oxygen species (ROS) generation, apoptosis, proliferation, and lipid transport, while their dysfunction is implicated in a broad spectrum of diseases, including cardiovascular disorders, neurodegenerative conditions, metabolic disorders, and cancer. This review aims to 1) summarize the experimental evidence on the impact of H2 on mitochondrial function; 2) provide an overview of the mitochondrial pathways underlying the biological effects of H2, and 3) discuss H2 metabolism in eukaryotic organisms and its relationship with mitochondria. Moreover, based on previous findings, this review proposes that H2 may regulate mitochondrial quality control through diverse pathways in response to varying degrees of mitochondrial damage. By combining the existing research evidence with an evolutionary perspective, this review emphasizes the potential hydrogenase activity in mitochondria of higher plants and animals. Finally, this review also addresses potential issues in the current mechanistic study and offers insights into future research directions, aiming to provide a reference for future studies on the mechanisms underlying the action of H2.

Clinical Use and Treatment Mechanism of Molecular Hydrogen in the Treatment of Various Kidney Diseases including Diabetic Kidney Disease

As diabetes rates surge globally, there is a corresponding rise in the number of patients suffering from diabetic kidney disease (DKD), a common complication of diabetes. DKD is a significant contributor to chronic kidney disease, often leading to end-stage renal failure. However, the effectiveness of current medical treatments for DKD leaves much to be desired. Molecular hydrogen (H2) is an antioxidant that selectively reduces hydroxyl radicals, a reactive oxygen species with a very potent oxidative capacity. Recent studies have demonstrated that H2 not only possesses antioxidant properties but also exhibits anti-inflammatory effects, regulates cell lethality, and modulates signal transduction. Consequently, it is now being utilized in clinical applications. Many factors contribute to the onset and progression of DKD, with mitochondrial dysfunction, oxidative stress, and inflammation being strongly implicated. Recent preclinical and clinical trials reported that substances with antioxidant properties may slow the progression of DKD. Hence, we undertook a comprehensive review of the literature focusing on animal models and human clinical trials where H2 demonstrated effectiveness against a variety of renal diseases. The collective evidence from this literature review, along with our previous findings, suggests that H2 may have therapeutic benefits for patients with DKD by enhancing mitochondrial function. To substantiate these findings, future large-scale clinical studies are needed.

Comprehensive brain tissue metabolomics and biological network technology to decipher the mechanism of hydrogen-rich water on Radiation-induced cognitive impairment in rats

BACKGROUND

Hydrogen-rich water (HRW) has been shown to prevent cognitive impairment caused by ionizing radiation. This study aimed to investigate the pharmacological effects and mechanisms of HRW on ionizing radiation by coupling the brain metabolomics and biological target network methods.

METHODS AND RESULTS

HRW significantly improves the cognitive impairment in rats exposed to ionizing radiation. Based on metabolomics and biological network results, we identified 54 differential metabolites and 93 target genes. The KEGG pathway indicates that glutathione metabolism, ascorbic acid and aldehyde acid metabolism, pentose and glucuronic acid interconversion, and glycerophospholipid metabolism play important roles in ionizing radiation therapy.

CONCLUSION

Our study has systematically elucidated the molecular mechanism of HRW against ionizing radiation, which can be mediated by modulating targets, pathways and metabolite levels. This provides a new perspective for identifying the underlying pharmacological mechanism of HRW.

Research progress on gas signal molecular therapy for Parkinson's disease

The pathogenesis of Parkinson's disease (PD) remains unclear. Among the pathological manifestations is the progressive degeneration of the nigrostriatal dopaminergic pathway, leading to massive loss of neurons in the substantia nigra pars compacta and dopamine (DA) depletion. Therefore, the current drug treatment is primarily based on DA supplementation and delaying the progression of the disease. However, as patients' symptoms continue to worsen, the drug effect will gradually decrease or even disappear, thereby further aggravating clinical symptoms. Gas signaling molecules, such as hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and hydrogen (H2), exhibit pleiotropic biological functions and play crucial roles in physiological and pathological effects. In common neurodegenerative diseases including Alzheimer's disease and PD, gas signal molecules can prevent or delay disease occurrence via the primary mechanisms of antioxidation, anti-inflammatory response, and antiapoptosis. This article reviews the therapeutic progress of gas signaling molecules in PD models and discusses the possibility of their clinical applications.

Hydrogen Attenuates Inflammation by Inducing Early M2 Macrophage Polarization in Skin Wound Healing

The heterogeneous and highly plastic cell populations of macrophages are important mediators of cellular responses during all stages of wound healing, especially in the inflammatory stage. Molecular hydrogen (H₂), which has potent antioxidant and anti-inflammatory effects, has been shown to promote M2 polarization in injury and disease. However, more in vivo time series studies of the role of M1-to-M2 polarization in wound healing are needed. In the current study, we performed time series experiments on a dorsal full-thickness skin defect mouse model in the inflammatory stage to examine the effects of H₂ inhalation. Our results revealed that H₂ could promote very early M1-to-M2 polarization (on days 2-3 post wounding, 2-3 days earlier than in conventional wound healing), without disturbing the functions of the M1 phenotype. Time series analysis of the transcriptome, blood cell counts, and multiple cytokines further indicated that peripheral blood monocytes were a source of H₂-induced M2 macrophages and that the functions of H₂ in macrophage polarization were not only dependent on its antioxidant effects. Therefore, we believe that H₂ could reduce inflammation in wound care by shifting early macrophage polarization in clinical settings.

Mast Cells as a Potential Target of Molecular Hydrogen in Regulating the Local Tissue Microenvironment

Knowledge of the biological effects of molecular hydrogen (H₂), hydrogen gas, is constantly advancing, giving a reason for the optimism in several healthcare practitioners regarding the management of multiple diseases, including socially significant ones (malignant neoplasms, diabetes mellitus, viral hepatitis, mental and behavioral disorders). However, mechanisms underlying the biological effects of H₂ are still being actively debated. In this review, we focus on mast cells as a potential target for H₂ at the specific tissue microenvironment level. H₂ regulates the processing of pro-inflammatory components of the mast cell secretome and their entry into the extracellular matrix; this can significantly affect the capacity of the integrated-buffer metabolism and the structure of the immune landscape of the local tissue microenvironment. The analysis performed highlights several potential mechanisms for developing the biological effects of H₂ and offers great opportunities for translating the obtained findings into clinical practice.

Research Progress of Hydrogen on Chronic Nasal Inflammation

Chronic nasal mucosal inflammatory disease is a common nasal disease, which is involved by inflammatory cells and a variety of cytokines. Its main pathological features are inflammatory reaction, increased secretion, mucosal swelling and thickening of nasal cavity or paranasal sinuses.It mainly includes chronic rhinitis (divided into allergic rhinitis, non-allergic rhinitis), chronic sinusitis (divided into with nasal polyps, without nasal polyps type), etc.The main symptoms of chronic rhinitis are nasal itching, sneezing, runny nose, and nasal congestion. The main symptoms of chronic sinusitis are nasal congestion, purulent or sticky nasal discharge, headache, and reduced sense of smell. They are a type of disease with a high incidence rate and seriously affect the quality of human life.Although the etiology and treatment of this type of disease have been extensively studied, there are still many aspects that are unclear.Currently, oxidative stress is believed to be an important link in the pathogenesis of chronic inflammatory diseases of the nasal mucosa. Therefore, anti-oxidative stress is a direction of research for the treatment of chronic nasal mucosal inflammatory diseases.Hydrogen, as a medically therapeutic gas, has been extensively studied for its antioxidant, anti-inflammatory, and anti-damage properties, and has been used in the treatment of various diseases.Although there are relatively few studies on the use of hydrogen for nasal inflammation, its positive effects have also been found. This article systematically summarizes the relevant research on the use of hydrogen to improve chronic nasal mucosal inflammation, with the aim of clarifying the ideas and indicating the direction for further research in the future.

Plasmon-activated water as a therapeutic strategy in Alzheimer's disease by altering gut microbiota

Gut microbiota (GM) are involved in the pathophysiology of Alzheimer's disease (AD) and might correlate to the machinery of the gut-brain axis. Alteration of the GM profiles becomes a potential therapy strategy in AD. Here, we found that plasmon-activated water (PAW) therapy altered GM profile and reduced AD symptoms in APPswe/PS1dE9 transgenic mice (AD mice). GM profile showed the difference between AD and WT mice. PAW therapy in AD mice altered GM profile and fecal microbiota transplantation (FMT) reproduced GM profile in AD mice. PAW therapy and FMT in AD mice reduced cognitive decline and amyloid accumulation by novel object recognition (NOR) test and amyloid PET imaging. Immunofluorescent staining and western blot analysis of β-amyloid (Aβ) and phosphorylated (p)-tau in the brain of AD mice were reduced in PAW therapy and FMT. The inflammatory markers, interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α and pro-inflammatory indicator of arginase-1/CD86 ratio were also reduced. Furthermore, immunohistochemistry (IHC) analysis of occludin and claudin-5 in the intestine and AXL in the brain were increased to correlate with the abundant GM in PAW therapy and FMT. Our results showed the machinery of gut-brain axis, and PAW might be a potential therapeutic strategy in AD.

Therapeutic Potential of Molecular Hydrogen in Metabolic Diseases from Bench to Bedside

Oxidative stress and chronic inflammation have been implicated in the pathophysiology of metabolic diseases, including diabetes mellitus (DM), metabolic syndrome (MS), fatty liver (FL), atherosclerosis (AS), and obesity. Molecular hydrogen (H₂) has long been considered a physiologically inert gas. In the last two decades, accumulating evidence from pre-clinical and clinical studies has indicated that H₂ may act as an antioxidant to exert therapeutic and preventive effects on various disorders, including metabolic diseases. However, the mechanisms underlying the action of H₂ remain unclear. The purpose of this review was to (1) provide an overview of the current research on the potential effects of H₂ on metabolic diseases; (2) discuss the possible mechanisms underlying these effects, including the canonical anti-oxidative, anti-inflammatory, and anti-apoptotic effects, as well as suppression of ER stress, activation of autophagy, improvement of mitochondrial function, regulation of gut microbiota, and other possible mechanisms. The potential target molecules of H₂ will also be discussed. With more high-quality clinical trials and in-depth mechanism research, it is believed that H₂ will eventually be applied to clinical practice in the future, to benefit more patients with metabolic disease.

Molecular Hydrogen: From Molecular Effects to Stem Cells Management and Tissue Regeneration

It is known that molecular hydrogen is a relatively stable, ubiquitous gas that is a minor component of the atmosphere. At the same time, in recent decades molecular hydrogen has been shown to have diverse biological effects. By the end of 2022, more than 2000 articles have been published in the field of hydrogen medicine, many of which are original studies. Despite the existence of several review articles on the biology of molecular hydrogen, many aspects of the research direction remain unsystematic. Therefore, the purpose of this review was to systematize ideas about the nature, characteristics, and mechanisms of the influence of molecular hydrogen on various types of cells, including stem cells. The historical aspects of the discovery of the biological activity of molecular hydrogen are presented. The ways of administering molecular hydrogen into the body are described. The molecular, cellular, tissue, and systemic effects of hydrogen are also reviewed. Specifically, the effect of hydrogen on various types of cells, including stem cells, is addressed. The existing literature indicates that the molecular and cellular effects of hydrogen qualify it to be a potentially effective agent in regenerative medicine.

Effectiveness and safety of hydrogen inhalation as an adjunct treatment in Chinese type 2 diabetes patients: A retrospective, observational, double-arm, real-life clinical study

Aim

To analyze the effectiveness and safety of hydrogen inhalation (HI) therapy as an adjunct treatment in Chinese type 2 diabetes mellitus (T2DM) patients in a real-life clinical setting.

Methods

This observational, non-interventional, retrospective, double-arm, 6-month clinical study included T2DM patients receiving conventional anti-diabetes medication with or without HI initiation from 2018 to 2021. Patients were assigned to the HI group or non-HI group (control group) after 1:1 propensity score matching (PSM). The mean change in glycated hemoglobin (HbA1c) after 6 months in different groups was evaluated primarily. The secondary outcome was composed of the mean change of fasting plasma glucose (FPG), weight, lipid profile, and homeostasis model assessment. Logistics regression was performed to evaluate the likelihood of reaching different HbA1c levels after 6-month treatment between the groups. Adverse event (AE) was also evaluated in patients of both groups.

Results

In total, 1088 patients were selected into the analysis. Compared to the control group, subjects in HI group maintained greater improvement in the level of HbA1c (-0.94% vs -0.46%), FPG (-22.7 mg/dL vs -11.7 mg/dL), total cholesterol (-12.9 mg/dL vs -4.4 mg/dL), HOMA-IR (-0.76 vs -0.17) and HOMA-β (8.2% vs 1.98%) with all p< 0.001 post the treatment. Logistics regression revealed that the likelihood of reaching HbA1c< 7%, ≥ 7% to< 8% and > 1% reduction at the follow-up period was higher in the HI group, while patients in the control group were more likely to attain HbA1c ≥ 9%. Patients in HI group was observed a lower incidence of several AEs including hypoglycemia (2.0% vs 6.8%), vomiting (2.6% vs 7.4%), constipation (1.7% vs 4.4%) and giddiness (3.3% vs 6.3%) with significance in comparison to the control group.

Conclusion

HI as an adjunct therapy ameliorates glycemic control, lipid metabolism, insulin resistance and AE incidence of T2DM patients after 6-month treatment, presenting a noteworthy inspiration to existing clinical diabetic treatment.

New Treatment for the Cognitive and Emotional Deficits Linked with Paclitaxel-Induced Peripheral Neuropathy in Mice

Chemotherapy-provoked peripheral neuropathy and its linked comorbidities severely reduce the quality of a patient's life. Its therapy is not completely resolved and has become an important clinical challenge. The protective actions of molecular hydrogen (H₂) in many neurological disorders have been described, but its effects on memory and the emotional deficits accompanying neuropathic pain induced by chemotherapy remain unknown. In this study, using male mice injected with paclitaxel (PTX), we examined the effects of systemic treatment with hydrogen-rich water (HRW) in: (i) the mechanical and thermal allodynia provoked by PTX and the pathways involved; (ii) the memory deficits, anxiety- and depressive-like behaviors associated with PTX-induced peripheral neuropathy (PIPN); and (iii) the plasticity (p-extracellular signal-regulated protein kinase; p-ERK ½), nociceptive (p-protein kinase B, p-Akt), inflammatory (p-nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha; p-IKBα), and oxidative (4-hydroxynonenal: 4-HNE) alterations provoked by PIPN in the prefrontal cortex (PFC). The results revealed: (1) the antiallodynic actions of HRW administered at one or two times per day during 7 and 3 consecutive days; (2) the participation of Kv7 potassium channels and the Nrf2-heme oxygenase 1-NAD(P)H: quinone oxidoreductase 1 pathway in the painkiller effects of HRW; (3) the inhibition of memory deficits and the anxiodepressive-like behaviors related with PIPN induced by HRW; and (4) the normalization of p-ERK ½, p-Akt and 4-HNE up-regulation and the activation of antioxidant enzymes produced by this treatment in PFC. This study proposes HRW as a possible effective and safe therapy for PIPN and its associated cognitive and emotional deficits.

Electrolyzed-Reduced Water: Review I. Molecular Hydrogen Is the Exclusive Agent Responsible for the Therapeutic Effects

Numerous benefits have been attributed to alkaline-electrolyzed-reduced water (ERW). Sometimes these claims are associated with easily debunked concepts. The observed benefits have been conjectured to be due to the intrinsic properties of ERW (e.g., negative oxidation-reduction potential (ORP), alkaline pH, H₂ gas), as well enigmatic characteristics (e.g., altered water structure, microclusters, free electrons, active hydrogen, mineral hydrides). The associated pseudoscientific marketing has contributed to the reluctance of mainstream science to accept ERW as having biological effects. Finally, through many in vitro and in vivo studies, each one of these propositions was examined and refuted one-by-one until it was conclusively demonstrated that H₂ was the exclusive agent responsible for both the negative ORP and the observed therapeutic effects of ERW. This article briefly apprised the history of ERW and comprehensively reviewed the sequential research demonstrating the importance of H₂. We illustrated that the effects of ERW could be readily explained by the known biological effects of H₂ and by utilizing conventional chemistry without requiring any metaphysical conjecture (e.g., microclustering, free electrons, etc.) or reliance on implausible notions (e.g., alkaline water neutralizes acidic waste). The H₂ concentration of ERW should be measured to ensure it is comparable to those used in clinical studies.

Hydrogen-Rich Water as a Novel Therapeutic Strategy for the Affective Disorders Linked with Chronic Neuropathic Pain in Mice

Neuropathic pain manifested with allodynia and hyperalgesia usually becomes a chronic condition accompanied with mood disorders. Clinical therapies for neuropathic pain are still unsatisfactory with notable side effects. Recent studies have reported the protective role of molecular hydrogen (H₂) in different diseases including neurological disorders, such as Alzheimer's as well as its antidepressant activities in animals with chronic stress. This study explored the effects of treatment with hydrogen-rich water (HRW) in male mice with neuropathic pain induced by the chronic constriction of the sciatic nerve (CCI) and the accompanying affective deficits. The likely pathways implied in the HRW analgesic activity, as well as the interaction between heme oxygenase 1 (HO-1) enzyme and H₂ during neuropathic pain were also studied. The results showed: (i) the inhibitory effects of the repetitive treatment with HRW on the allodynia and hyperalgesia provoked by CCI; (ii) the anxiolytic and antidepressant actions of HRW in animals with neuropathic pain; (iii) the contribution of the antioxidant enzymes (HO-1 and NAD(P)H: quinone oxidoreductase 1) and the ATP sensitive potassium channels in the painkiller activities of HRW during neuropathic pain; (iv) a positive interaction between the HO-1 and H₂ systems in inhibiting the CCI-induced neuropathy; and (v) the antioxidant, antinociceptive, anti-inflammatory and/or antiapoptotic features of HRW treatment in the dorsal root ganglia and/or amygdala of sciatic nerve-injured mice. This study demonstrates new protective actions of H₂ and suggests that treatment with HRW might be an interesting therapeutic strategy for chronic neuropathic pain and its associated mood disorders.

The Beneficial Effects of Hydrogen-Rich Saline Irrigation on Chronic Rhinitis: A Randomized, Double-Blind Clinical Trial

Purpose

Chronic rhinitis (CR) is a common chronic inflammation of the nasal mucosa. Nasal saline irrigation has been demonstrated to be an effective treatment for CR. In this study, we investigated the beneficial effects of hydrogen-rich saline irrigation as an anti-inflammatory irrigation therapy for CR and compared its effectiveness over saline irrigation. Hydrogen-rich saline (HRS) was investigated due to its antioxidant and anti-inflammatory properties.

Methods

A total of 120 patients with CR were randomly divided into two groups, patients irrigated with HR (HRS group) and the control group irrigated with saline (NS group). A randomized, double-blind control study was performed. The main observation index in this study was the total score of nasal symptoms (TNSS). In addition, eosinophilic protein (ECP) of the nasal secretions, nasal nitric oxide (nNO) levels, and levels of regulatory T cells (Treg) and regulatory B cells (Breg) were also compared between the two groups. Furthermore, patients with allergic rhinitis (AR) and non-allergic rhinitis (NAR) were also evaluated based on serum-specific IgE positivity.

Results

After treatment, TNSS and nasal ECP in the two groups decreased significantly (P<0.05), with patients in the HRS group showing significantly lower levels compared to the NS group (P<0.05). There were no significant differences in Treg and Breg levels between the two groups. Subgroup analysis showed that TNSS in the AR-HRS group showed a more significant reduction compared to the AR-NS group (P<0.05); however, there were no significant differences for the other inflammatory biomarkers (P>0.05). ECP levels were reduced significantly in the NAR subgroup compared to NS irrigation (P<0.05). There were no obvious adverse events observed in patients during the entire treatment period.

Conclusion

Compared to saline irrigation, HRS nasal irrigation was found to improve CR clinical symptoms, especially in patients with AR. HRS could effectively be used for the clinical treatment of patients with CR.

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Hydrogen-rich water reduced oxidative stress and renal fibrosis in rats with unilateral ureteral obstruction

BACKGROUND

Congenital obstructive nephropathy (CKD) is commonly implicated in the pathophysiology of chronic kidney disease occurring in the pediatric and adolescent age groups and the release of reactive oxygen species contribute to the worsening of renal fibrosis. Molecular hydrogen (H₂) protects against tissue injury by reducing oxidative stress. We evaluated the efficacy of oral H₂-rich water (HW) intake in preventing unilateral ureteral obstruction (UUO)-induced renal injury in rats.

METHODS

Male Sprague-Dawley UUO or control rats were administered with distilled water (DW) or HW for 2 weeks post-surgery. Histopathological and immunohistochemical analyses of kidney samples were performed.

RESULTS

Histological changes were not apparent in the sham-operated kidneys. However, UUO kidneys were found to have widened interstitial spaces and tubular dilatation. Compared with the UUO + DW group, HW administration attenuated tubulointerstitial injury and reduced interstitial fibrotic area, causing a substantial decline in the frequency of α-SMA-, ED-1-, and TGF-β1-positive cells in the UUO + HW group. The decrease in the klotho mRNA expression in the UUO + HW group was less pronounced than that in the UUO + DW group.

CONCLUSION

Oral HW intake reduced oxidative stress and prevented interstitial fibrosis in UUO kidneys, potentially involving klotho in the underlying mechanism.

IMPACT

Oral intake of hydrogen-rich water (HW) can reduce oxidative stress and suppress interstitial fibrosis in unilateral ureteral obstruction-induced renal injury in rats. This mechanism possibly involves klotho, which is known for its antiaging roles. The association between molecular hydrogen and klotho in renal fibrosis is well known; this is the first report on the association in a unilateral ureteral obstruction model. Drinking HW is a safe and convenient treatment for oxidative stress-induced pathologies, without side effects. As a prospect for future research, oral HW intake to treat oxidative stress may improve renal fibrosis in congenital obstructive nephropathy.

Molecular Hydrogen as a Medical Gas for the Treatment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Possible Efficacy Based on a Literature Review

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disorder that is characterized by fatigue that persists for more than 6 months, weakness, sleep disturbances, and cognitive dysfunction. There are multiple possible etiologies for ME/CFS, among which mitochondrial dysfunction plays a major role in abnormal energy metabolism. The potential of many substances for the treatment of ME/CFS has been examined; however, satisfactory outcomes have not yet been achieved. The development of new substances for curative, not symptomatic, treatments is desired. Molecular hydrogen (H2) ameliorates mitochondrial dysfunction by scavenging hydroxyl radicals, the most potent oxidant among reactive oxygen species. Animal experiments and clinical trials reported that H2 exerted ameliorative effects on acute and chronic fatigue. Therefore, we conducted a literature review on the mechanism by which H2 improves acute and chronic fatigue in animals and healthy people and showed that the attenuation of mitochondrial dysfunction by H2 may be involved in the ameliorative effects. Although further clinical trials are needed to determine the efficacy and mechanism of H2 gas in ME/CFS, our literature review suggested that H2 gas may be an effective medical gas for the treatment of ME/CFS.

Protective Effects of Hydrogen-Rich Saline on Experimental Intestinal Volvulus in Rats

BACKGROUND

Intestinal volvulus can cause morbidity and mortality. Surgical reduction, on the other hand, could result in ischemia-reperfusion (I/R) injury. Hydrogen rich saline solution (HRSS neutralizes free radicals in the body. This study aimed to investigate the effects of HRSS in I/R injury in experimental intestinal volvulus in rats.

METHODS

Thirty rats were randomly allocated into 5 groups. All procedures were done under general anesthesia and sterile conditions in each animal. Five ml/kg of saline and HRSS were administered intraperitoneally (ip) in Sham (Group 1) and HRSS (Group 2) groups, respectively. Groups 3, 4, and 5 constituted the study groups in which volvulus was created in a 5-cm- long ileal segment 2 cm proximal to the ileocecal valve. After 2 hours the volvuli were reduced and following 2 hours of reperfusion, these segments were removed. In volvulus-I/R group (Group 3) no additional procedure was done. HRSS was administered shortly before reperfusion (reduction of the volvulus) in Treatment I (Group 4) and 1 h before experimental volvulus in Treatment II (Group 5) groups. Blood and intestinal tissue samples were obtained from all rats at the 4th hour. Both tissue and blood total oxidant (TOS) and antioxidant status (TAS) levels were determined and tissue histomorphologies were studied. Oxidative stress indices (TOS ÷ TAS) (OSI) were calculated.

RESULTS

Tissue TOS and OSI levels and histomorphological injury scores were statistically lower in treatment groups than I/R group, whereas blood TOS and OSI levels were similar between the groups.

CONCLUSIONS

This study provides biochemical and histomorphological evidence that HRSS prevents intestinal damage in I/R injury caused by volvulus.

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.

Evaluation of the hydrogen-rich water alleviation potential on mercury toxicity in earthworms using ATR-FTIR and LC-ESI-MS/MS spectroscopy

The toxic effects of mercury in earthworms and the potential alleviation effect of hydrogen-rich water (HRW) using ATR-FTIR and LC-MS analysis methods were investigated. Different concentrations of mercury chloride (H1: 5 µg/mL, H2: 10 µg/mL, H3: 20 µg/mL, H4: 40 µg/mL, and C1: control) and mercury chloride prepared in hydrogen-rich water (H5: 5 µg/mL, H6: 10 µg/mL, H7: 20 µg/mL, H8: 40 µg/mL, and C2: control) were injected into earthworms. The changes and reductions in some bands representing proteins, lipids, and polysaccharides (3280 cm^-1, 2922 cm^-1, 2855 cm^-1, 1170 cm^-1, and 1047 cm^-1) showed that protective effects could occur in groups prepared with hydrogen-rich water. In the FTIR results, it was found that these bands in the H3 group were more affected and decreased by the influence of mercury on earthworms than the H7 group prepared with hydrogen. LC-MS analysis showed that the changes in some ions of the highest dose groups (H4 and H8) were different, and mercury caused oxidative DNA damage in earthworms. When the high-level application groups of mercury, i.e., H4 and H8 were compared with the controls, the ion exchange ([M + H] + ; m/z 283.1) representing the 8-Oxo-dG level in earthworms was higher in the H4 group than the H8 group. This reveals that HRW exhibited the potential ability to alleviate the toxic effects of mercury; however, a longer period of HRW treatment may be necessary to distinguish an obvious effect. The ATR-FTIR spectroscopy provided a rapid and precise method for monitoring the changes in biological tissues caused by a toxic compound at the molecular level.

Molecular hydrogen is a promising therapeutic agent for pulmonary disease

Molecular hydrogen exerts biological effects on nearly all organs. It has anti-oxidative, anti-inflammatory, and anti-aging effects and contributes to the regulation of autophagy and cell death. As the primary organ for gas exchange, the lungs are constantly exposed to various harmful environmental irritants. Short- or long-term exposure to these harmful substances often results in lung injury, causing respiratory and lung diseases. Acute and chronic respiratory diseases have high rates of morbidity and mortality and have become a major public health concern worldwide. For example, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. An increasing number of studies have revealed that hydrogen may protect the lungs from diverse diseases, including acute lung injury, chronic obstructive pulmonary disease, asthma, lung cancer, pulmonary arterial hypertension, and pulmonary fibrosis. In this review, we highlight the multiple functions of hydrogen and the mechanisms underlying its protective effects in various lung diseases, with a focus on its roles in disease pathogenesis and clinical significance.

Hydrogen-rich water ameliorates neuropathological impairments in a mouse model of Alzheimer's disease through reducing neuroinflammation and modulating intestinal microbiota

Hydrogen exhibits the potential to treat Alzheimer's disease. Stereotactic injection has been previously used as an invasive method of administering active hydrogen, but this method has limitations in clinical practice. In this study, triple transgenic (3×Tg) Alzheimer's disease mice were treated with hydrogen-rich water for 7 months. The results showed that hydrogen-rich water prevented synaptic loss and neuronal death, inhibited senile plaques, and reduced hyperphosphorylated tau and neurofibrillary tangles in 3×Tg Alzheimer's disease mice. In addition, hydrogen-rich water improved brain energy metabolism disorders and intestinal flora imbalances and reduced inflammatory reactions. These findings suggest that hydrogen-rich water is an effective hydrogen donor that can treat Alzheimer's disease. This study was approved by the Animal Ethics and Welfare Committee of Shenzhen University, China (approval No. AEWC-20140615-002) on June 15, 2014.

Quantification of dissolved H2 and continuous monitoring of hydrogen-rich water for haemodialysis applications: An experimental study

The prevalence of oxidative and inflammatory stress in end-stage renal disease (ESRD) patients has often been associated with chronic haemodialysis therapies. Over the past decades, several reports have shown the potential of hydrogen molecule as an antioxidant in the treatment of various medical conditions in animal models, as well as in pilot studies with human patients. Recently, a hydrogen-enriched dialysate solution has been introduced, holding promise in reducing the oxidative and/or inflammatory complications arising during haemodialysis. To this end, a standardised measuring method to determine the levels of hydrogen in dialysate and subsequently in blood is required. This study explores the possibility of quantifying hydrogen concentration using a novel contactless sensor that detects dissolved hydrogen in liquids. An experimental circuit is assembled to validate the sensitivity and accuracy of the hydrogen monitoring system (Pureron Japan Co., Ltd) through in vitro investigations with physiological solutions. Measurements of dissolved molecular hydrogen concentration are corroborated by an established oxygen sensor providing continuous partial pressure readings. The relationship between the applied H₂ content in the gaseous mixture and the H₂ concentration value at equilibrium is linear. At the same time, the hydrogen monitoring system has a rather long response time, and its readings seem to slightly diverge from sensor to sensor as well as at different temperatures. For this reason, a sensor recalibration might be necessary, which could become part of the product's ongoing development. Nevertheless, the aforementioned minor deficiencies can be mostly considered negligible in applications such as haemodialysis.

Response of Escherichia coli to hydrogen nanobubbles: an in vitro evaluation using synchrotron infrared spectroscopy

Hydrogen (H₂)-rich water, an apparent source of molecular H₂, is an emerging functional drink with many purported benefits for human health (Yang et al., 2020; Ostojic, 2021). The preventive and therapeutic effects of H₂ on various pathological processes have been intensively investigated in numerous clinical trials; it is commonly believed that the beneficial effects are mainly attributed to its selective antioxidant and anti-inflammatory properties (Lee et al., 2015; Ohta, 2015; LeBaron et al., 2019; Qiu et al., 2020). In recent years, a handful of rodent studies revealed that exogenous H₂ can affect the gut microbiota (Sha et al., 2018; Valdes et al., 2018). For example, H₂ was reported to induce a higher abundance of butyrate-producing bacteria in a rat model of Parkinson's disease (Bordoni et al., 2019). Recent first-in-human trials have explored the effects of the long-term consumption of H₂-rich water on antioxidant activity and the gut flora (Sha et al., 2018; Suzuki et al., 2018). Although these promising results suggest that the intestinal microbiota may be another plausible target for molecular H₂, more studies are highly warranted to explain the mechanism(s) of H₂ action on bacterial growth and functions.

Development of Alkaline Reduced Water Using High-Temperature-Roasted Mineral Salt and Its Antioxidative Effect in RAW 264.7 Murine Macrophage Cell Line

Oxidative stress (OS) plays an important role in many diseases, and its excessive increase affects human health. Although the antioxidant effect of sea salt can be strengthened through special processing, it is scarcely studied. This study confirmed the antioxidative effect of high-temperature roasted mineral salt (HtRMS) produced through repeated roasting of sea salt at high temperature in a ceramic vessel. The dissolved HtRMS exhibited properties such as high alkalinity, rich mineral content, and a high concentration of hydrogen (H2). To detect the antioxidative effect of HtRMS, OS was induced in RAW 264.7 murine macrophage cells with hydrogen peroxide (H2O2) and lipopolysaccharide (LPS), and then treated with HtRMS solution at different concentrations (0.1, 1, and 10%). Cell viability, reactive oxygen species (ROS), nitric oxide (NO), and antioxidant enzymes such as catalase (CAT) and glutathione peroxidase (GPx), Ca2+, and mitogen-activated protein kinase (MAPK) pathway-related proteins (p-p38, p-JNK, and p-ERK) were measured. OS was significantly induced by treatment with H2O2 and LPS (p < 0.001). After treatment with HtRMS, cell viability and GPx activities significantly increased and ROS, NO, Ca2+, and CAT significantly decreased in a concentration-dependent manner compared to H2O2 and LPS-only groups, which was not observed in tap water (TW)-treated groups. Similarly, p-p38, p-JNK, and p-ERK levels significantly decreased in a concentration-dependent manner in HtRMS groups compared to both H2O2 and LPS-only groups; however, those in TW groups did not exhibit significant differences compared to H2O2 and LPS-only groups. In conclusion, our results suggest that HtRMS may have antioxidant potential by regulating the MAPK signaling pathway.

Combating Oxidative Stress and Inflammation in COVID-19 by Molecular Hydrogen Therapy: Mechanisms and Perspectives

COVID-19 is a widespread global pandemic with nearly 185 million confirmed cases and about four million deaths. It is caused by an infection with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which primarily affects the alveolar type II pneumocytes. The infection induces pathological responses including increased inflammation, oxidative stress, and apoptosis. This situation results in impaired gas exchange, hypoxia, and other sequelae that lead to multisystem organ failure and death. As summarized in this article, many interventions and therapeutics have been proposed and investigated to combat the viral infection-induced inflammation and oxidative stress that contributes to the etiology and pathogenesis of COVID-19. However, these methods have not significantly improved treatment outcomes. This may partly be attributable to their inability at restoring redox and inflammatory homeostasis, for which molecular hydrogen (H2), an emerging novel medical gas, may complement. Herein, we systematically review the antioxidative, anti-inflammatory, and antiapoptotic mechanisms of H2. Its small molecular size and nonpolarity allow H2 to rapidly diffuse through cell membranes and penetrate cellular organelles. H2 has been demonstrated to suppress NF-κB inflammatory signaling and induce the Nrf2/Keap1 antioxidant pathway, as well as to improve mitochondrial function and enhance cellular bioenergetics. Many preclinical and clinical studies have demonstrated the beneficial effects of H2 in varying diseases, including COVID-19. However, the exact mechanisms, primary modes of action, and its true clinical effects remain to be delineated and verified. Accordingly, additional mechanistic and clinical research into this novel medical gas to combat COVID-19 complications is warranted.

Molecular hydrogen suppresses Porphyromonas gingivalis lipopolysaccharide-induced increases in interleukin-1 alpha and interleukin-6 secretion in human gingival cells

Periodontitis is defined as a multifactorial polymicrobial infection accompanied by inflammatory reactions. Porphyromonas gingivalis (Pg) is known as a major pathogen in the initiation and progression of periodontitis, and a major virulence factor is Pg lipopolysaccharide (LPS). Molecular hydrogen (H₂) has been reported to act as a gaseous antioxidant, which suppresses periodontitis progression by decreasing gingival oxidative stress. However, no human periodontitis model has examined the anti-inflammatory effects of H₂. In this study, we examined the effects of H₂ on Pg LPS-induced secretion of 8 types of inflammation markers in a human periodontitis model using human gingival cells with enzyme-linked immunosorbent assays. Our results demonstrated that Pg LPS increased interleukin (IL) 1 alpha (IL-1α) and IL-6 secretion, but H₂ significantly suppressed the secretion of both cytokines without cytotoxicity. H₂ can suppress the production of IL-1α and IL-6, which are identified as cytokines involved in inflammatory reactions in periodontal disease. Thus, H₂ may provide therapeutic applications for periodontitis.

Interaction between gender and post resuscitation interventions on neurological outcome in an asphyxial rat model of cardiac arrest

PURPOSE

Previous clinical studies have suggested an effect of gender on outcome after out-of-hospital cardiac arrest, but the results are conflicting and there is no uniform agreement regarding gender differences in survival and prognosis. The present study was aimed to investigate the interaction between gender and post resuscitation interventions on neurological outcome in an asphyxial rat model of cardiac arrest.

METHODS

Asphyxia was induced by blocking the endotracheal tube in 120 adult Sprague-Dawley rats (60 males and 60 females) at the same age. Cardiopulmonary resuscitation (CPR) was started after 5 min of untreated cardiac arrest. Animals were randomized into one of the three post resuscitation care intervention groups (n = 40, 20 males) immediately after resuscitation: (1) normothermic control (NC): ventilated with 2% N2/98% O2 for 1 h under normothermia; (2) targeted temperature management (TTM): ventilated with 2% N2/98% O2 for 1 h under hypothermia; (3) hydrogen inhalation (HI): ventilated with 2% H2/98% O2 for 1 h under normothermia. Physiological variables were recorded during the 5 h post resuscitation monitoring period. Neurological deficit score (NDS) and accumulative survival were used to assess 96 h outcomes. Mutual independence analysis and Mantel-Haenszel stratified analysis were used to explore the associations among gender, intervention and survival.

RESULTS

The body weights of female rats were significantly lighter than males, but CPR characteristics did not differ between genders. Compared with male rats, females had significantly lower mean arterial pressure, longer onset time of the electroencephalogram (EEG) burst and time to normal EEG trace (TTNT) in the NC group; relatively longer TTNT in the TTM group; and substantially longer TTNT, lower NDSs, and higher survival in the HI group. Mutual independence analysis revealed that both gender and intervention were associated with neurological outcome. Mantel-Haenszel stratified analysis demonstrated that female rats had significantly higher survival rate than males when adjusted for the confounder intervention.

CONCLUSION

In this rat model cardiac arrest and CPR, gender did not affect resuscitation but associated with neurological outcome. The superiority of female rats in neurological recovery was affected by post resuscitation interventions and female rats were more likely to benefit from hydrogen therapy.

Emerging Antibacterial Strategies with Application of Targeting Drug Delivery System and Combined Treatment

At present, some bacteria have developed significant resistance to almost all available antibiotics. One of the reasons that cannot be ignored is long-term exposure of bacteria to the sub-minimum inhibitory concentration (MIC) of antibiotics. Therefore, it is necessary to develop a targeted antibiotic delivery system to improve drug delivery behavior, in order to delay the generation of bacterial drug resistance. In recent years, with the continuous development of nanotechnology, various types of nanocarriers that respond to the infection microenvironment, targeting specific bacterial targets, and targeting infected cells, and so on, are gradually being used in the delivery of antibacterial agents to increase the concentration of drugs at the site of infection and reduce the side effects of drugs in normal tissues. Here, this article describes in detail the latest research progress on nanocarriers for antimicrobial, and commonly used targeted antimicrobial strategies. The advantages of the combination of nanotechnology and targeting strategies in combating bacterial infections are highlighted in this review, and the upcoming opportunities and remaining challenges in this field are rationally prospected.

Hydrogen-rich saline reduces tissue injury and improves skin flap survival on a rat hindlimb degloving injury model

BACKGROUND

Degloving injuries represent a challenge in plastic surgery. The aim of this study is to acknowledge the protective effects of hydrogen-rich saline (HRS) solution on a rat hindlimb degloved skin flap.

METHODS

Twenty-one Sprague-Dawley rats were divided into three groups (control, saline and HRS). Degloving injury model was established, and flaps were sutured back following 5 min of ischemia. The control group did not receive any treatment. The saline group received intraperitoneal physiological saline (10 ml/kg) and the HRS group received intraperitoneal HRS solution (10 ml/kg) postoperatively and daily for 5 days after the operation. Skin samples were obtained for histological, immunohistochemical and biochemical evaluations.

RESULTS

Inflammation was lower in the HRS compared with saline (p = 0.02) and control (p = 0.004) groups. Edema was lower in the HRS compared with saline (p = 0.02) and control (p = 0.001) groups. Malondialdehyde (MDA) level was lower in the HRS than the control group (p = 0.01). Total antioxidant level was higher in the HRS compared with saline (p = 0.009) and control (p = 0.03) groups. Total oxidant level was lower in the HRS than the control group (p = 0.02). Oxidative stress index was lower in the HRS compared with saline (p = 0.001) and control (p = 0.0001) groups`. Vascular proliferation was higher in the HRS compared with the control group (p = 0.01).

CONCLUSION

Repeated HRS injections after trauma increased the viability of skin flap in rat degloving injury model by decreasing local tissue injury, due to its antioxidant, anti-inflammatory and angiogenic effects.

Molecular Hydrogen as a Novel Antitumor Agent: Possible Mechanisms Underlying Gene Expression

While many antitumor drugs have yielded unsatisfactory therapeutic results, drugs are one of the most prevalent therapeutic measures for the treatment of cancer. The development of cancer largely results from mutations in nuclear DNA, as well as from those in mitochondrial DNA (mtDNA). Molecular hydrogen (H₂), an inert molecule, can scavenge hydroxyl radicals (·OH), which are known to be the strongest oxidizing reactive oxygen species (ROS) in the body that causes these DNA mutations. It has been reported that H₂ has no side effects, unlike conventional antitumor drugs, and that it is effective against many diseases caused by oxidative stress and chronic inflammation. Recently, there has been an increasing number of papers on the efficacy of H₂ against cancer and its effects in mitigating the side effects of cancer treatment. In this review, we demonstrate the efficacy and safety of H₂ as a novel antitumor agent and show that its mechanisms may not only involve the direct scavenging of ·OH, but also other indirect biological defense mechanisms via the regulation of gene expression.

Protective effects of hydrogen rich saline solution on ventral penile mathieu type flap with penile tourniquet application in rats

INTRODUCTION

Penile tourniquet (Pt) application aims to work in a bloodless field in penile surgery. When the tourniquet is released, reperfusion injury occurs with the resumption of blood flow. Molecular hydrogen can easily attach to biomembranes and enter cytosol, mitochondria and other organelles of the cell and convert the formed OH- to H₂O to prevent cell and tissue damage.

AIM

We investigated the effects of hydrogen rich saline solution (HRSS) on penile Mathieu type flap tissue with Pt application in rats.

STUDY DESIGN

Thirty-six Wistar-albino male rats were randomly divided into six groups. No operations were performed in the Sham group. Ventral penile Mathieu type flap was prepared and Pt was applied to the root of the penis with a plastic band in other groups. Pt was applied 10 and 30 min in the PT¹⁰ and PT³⁰ groups. HRSS was injected intraperitoneally (ip) 5 ml/kg just before Pt was released in the HRSS¹⁰ and HRSS³⁰ groups. In the HRSS^B group, HRSS was injected 1 h before 10 min of Pt application. At the 4th hour of experiments the rats were sacrificed and tissue samples were taken for biochemical and histopathological studies. Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), myeloperoxidase (MPO), malondialdehyde (MDA) and glutathione (GSH) levels were determined in the penile tissue. The results were analyzed with one-way ANOVA and Pearson's Chi-Squared test.

RESULTS

Tissue MDA, MPO, IL-6 and TNF-α values were significantly lower in all HRSS groups compared to PT¹⁰ and PT³⁰ groups. Tissue GSH levels of HRSS groups were higher compared to PT groups. Histopathologically, inflammation was found to be higher in PT groups compared to HRSS groups. Interestingly, in the HRSS^B group with HRSS administration prior to Pt, the damage was less in grade, but not statistically different than the other HRSS groups (p > 0.05).

DISCUSSION

In previous studies, damage in histopathological examinations after Pt could only be demonstrated long after tourniquet applications such as 24 h and with longer duration of Pt such as 30 min. Structural changes in different Pt application times could be demonstrated at 60 min by electron microscopy and 48 h by light microscopy. In this study, the histopathological effect of Pt application could be demonstrated at the 4th hour after release and HRSS was observed to reduce the damage histopathologically as well as biochemically with its anti-inflammatory and antioxidant effects. It was observed that administration of HRSS either before or following Pt did not cause an alteration statistically.

CONCLUSION

HRSS reduces tissue oxidative stress and inflammation on the flap tissue and has a protective effect in Pt applied to the hypospadias model created with a penile flap.

Hydrogen therapy can be used to control tumor progression and alleviate the adverse events of medications in patients with advanced non-small cell lung cancer

Chemotherapy, targeted therapy, and immunotherapy are used against advanced non-small cell lung cancer. A clinically efficacious method for relieving the adverse events associated of such therapies is lacking. Fifty-eight adult patients were enrolled in our trial to relieve pulmonary symptoms or the adverse events of drugs. Twenty patients who refused drug treatment were assigned equally and randomly to a hydrogen (H₂)-only group and a control group. According to the results of tumor-gene mutations and drug-sensitivity tests, 10, 18, and 10 patients were enrolled into chemotherapy, targeted therapy, and immunotherapy groups in which these therapies were combined with H₂-therapy, respectively. Patients underwent H₂ inhalation for 4–5 hours per day for 5 months or stopped when cancer recurrence. Before study initiation, the demographics (except for tumor-mutation genes) and pulmonary symptoms (except for moderate cough) of the five groups showed no significant difference. During the first 5 months of treatment, the prevalence of symptoms of the control group increased gradually, whereas that of the four treatment groups decreased gradually. After 16 months of follow-up, progression-free survival of the control group was lower than that of the H₂-only group, and significantly lower than that of H₂ + chemotherapy, H₂ + targeted therapy, and H₂ + immunotherapy groups. In the combined-therapy groups, most drug-associated adverse events decreased gradually or even disappeared. H₂ inhalation was first discovered in the clinic that can be used to control tumor progression and alleviate the adverse events of medications for patients with advanced non-small cell lung cancer. This study was approved by the Ethics Committee of Fuda Cancer Hospital of Jinan University on December 7, 2018 (approval No. Fuda20181207), and was registered at ClinicalTrials.gov (Identifier: NCT03818347) on January 28, 2019.