Hydrogen gas inhalation alleviates oxidative stress in patients with post-cardiac arrest syndrome

Hydrogen gas inhalation therapy may not work sufficiently to mitigate oxidative stress induced with REBOA

Hemorrhagic shock is a significant cause of trauma-related mortality. Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a less-invasive aortic occlusion maneuver for severe hemorrhagic shock but potentially inducing oxidative stress injuries. In an animal model, this study investigated hydrogen gas inhalation therapy's potential to mitigate post-REBOA ischemia-reperfusion injuries (IRIs). Ten healthy female swine underwent REBOA placement after induced 40% hemorrhagic shock. They were observed during the IRI phase after a 60-minute Zone 1 occlusion for 180 minutes until euthanasia. 2% hydrogen gas inhalation was started simultaneously with REBOA inflation in the hydrogen group. We evaluated survival time, lactate, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) biomarkers, gross findings, and pathological grades. One swine in the control group died at 90 min, and the remaining animals survived throughout the experiment. Survival analysis showed no significant differences between the two groups (control vs. hydrogen, 4/5 vs. 5/5; Log-rank, P = 0.317). Lactate levels during and after REBOA suggested a tendency towards lower levels in the hydrogen group (10.5 ± 4.2 vs. 7.6 ± 2.3 mmol/L, peak, T = 90). Serum 8-OHdG concentrations showed a lower trend in the hydrogen group (Range: 0.12-0.32 vs. 0.11-0.19 ng/mL). The villi of the ileum were destroyed during REBOA inflation and after reperfusion. Changes in the pathological grade of the ileum demonstrated no significant differences in both groups (2.8 ± 1.0 vs. 2.0 ± 1.0, proximal ileum, T = 240). Hydrogen gas inhalation therapy exhibited no significant difference compared to the control group in survival, lactate level, 8-OHdG, and intestinal mucosal injury following REBOA in a hemorrhagic shock model. Although it may slightly reduce mortality, biomarkers, and intestinal pathology, hydrogen gas inhalation therapy was not shown to have sufficient evidence to mitigate REBOA-IRI.

Using oral molecular hydrogen supplements to combat microinflammation in humans: a pilot observational study

Background: Persistent inflammation over time can cause gradual harm to the body. Molecular hydrogen has the potential to specifically counteract reactive oxygen species (ROS), reduce disease severity, and enhance overall health. Investigations of the anti-inflammatory and antioxidant properties of oral solid hydrogen capsules (OSHCs) are currently limited, prompting our examination of the beneficial effects of OSHCs. Subsequently, we conducted a clinical study to assess the impact of OSHCs supplementation on individuals with chronic inflammation. Materials and methods: Initially, we evaluated the oxidative reduction potential (ORP) properties of the OSHCs solution by comparing it to hydrogen-rich water (HRW) and calcium hydride (CaH2) treated water. In our outpatient department, stable patients with chronic illnesses who were treated with varying doses of OSHCs were randomized into low-, medium-, and high-dose groups for 4 weeks. Primary outcomes included changes in the serum erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) concentrations after four weeks of OSHCs consumption. Secondary outcomes included changes in the Brief Fatigue Inventory-Taiwan (BFI-T) fatigue scale, Control Status Scale for Diabetes (CSSD70) scores, and Disease Activity Score 28 (DAS28). Results: Compared to HRW and CaH2, OSHCs demonstrated a prolonged reduction in ORP for 60 minutes in vitro and enabled a regulated release of hydrogen over 24 hours. A total of 30 participants, with 10 in each dosage (low/medium/high) group, completed the study. The average ESR120 significantly decreased from the first week to the fourth week, with a noticeable dose effect (low-dose group, p = 0.494; high-dose group, p = 0.016). Overall, the average CRP concentration showed a distinct decreasing trend after four weeks of OSHCs administration (w0 vs. w4, p = 0.077). The average DAS28 score demonstrated a significant decrease following OSHCs treatment. Furthermore, there were improvements in the BFI-T and CSSD70 scores. Conclusion: OSHCs supplementation may exert anti-inflammatory and antioxidant effects on individuals with chronic inflammation. However, further clinical studies could be investigated to explore the potential therapeutic effects of OSHCs.

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.

The Effect of Targeted Temperature Therapy on Antioxidant Levels in Patients With Spontaneous Circulation After Cardiac Arrest

Introduction In this study, we aimed to measure the change in total antioxidant status (TAS), total oxidant stress (TOS), oxidative stress index (OSI), and nuclear factor erythroid 2 (Nrf-2) levels during the treatment period in patients who restored spontaneous circulation return after cardiac arrest with targeted temperature management (TTM) therapy in our hospital. Methods The study included 36 patients who were hospitalized in the anesthesia intensive care unit and coronary intensive care unit of our hospital and were treated with TTM therapy after cardiac arrest. TAS, TOS, OSI, and Nrf-2 levels were measured at 0 (beginning), 12, 24, and 48 (end) hours of TTM therapy. Results The mean age of the patients participating in the study was 54.25±17.10. TAS and TOS levels decreased gradually during TTM therapy, but statistically significant decrease was observed at the end of the hour. When Nrf-2 and OSI levels were evaluated, it was found that no statistically significant difference was observed during the TTM therapy. Conclusion In our study, the oxidant-antioxidant balance was preserved in patients who received TTM therapy after cardiac arrest. We predict TTM therapy is effective on oxidative stress after cardiac arrest and should be applied for at least 48 hours.

Neuroprotective Approaches for Brain Injury After Cardiac Arrest: Current Trends and Prospective Avenues

With the implementation of improved bystander cardiopulmonary resuscitation techniques and public-access defibrillation, survival after out-of-hospital cardiac arrest (OHCA) has increased significantly over the years. Nevertheless, OHCA survivors have residual anoxia/reperfusion brain damage and associated neurological impairment resulting in poor quality of life. Extracorporeal membrane oxygenation or targeted temperature management has proven effective in improving post-cardiac arrest (CA) neurological outcomes, yet considering the substantial healthcare costs and resources involved, there is an urgent need for alternative treatment strategies that are crucial to alleviate brain injury and promote recovery of neurological function after CA. In this review, we searched PubMed for the latest preclinical or clinical studies (2016-2023) utilizing gas-mediated, pharmacological, or stem cell-based neuroprotective approaches after CA. Preclinical studies utilizing various gases (nitric oxide, hydrogen, hydrogen sulfide, carbon monoxide, argon, and xenon), pharmacological agents targeting specific CA-related pathophysiology, and stem cells have shown promising results in rodent and porcine models of CA. Although inhaled gases and several pharmacological agents have entered clinical trials, most have failed to demonstrate therapeutic effects in CA patients. To date, stem cell therapies have not been reported in clinical trials for CA. A relatively small number of preclinical stem-cell studies with subtle therapeutic benefits and unelucidated mechanistic explanations warrant the need for further preclinical studies including the improvement of their therapeutic potential. The current state of the field is discussed and the exciting potential of stem-cell therapy to abate neurological dysfunction following CA is highlighted.

Mechanisms and treatment of anemia related to cardiac arrest

Cardiac arrest is a common and fatal emergency situation. Recently, an increasing number of studies have shown that anemia in patients with cardiac arrest is closely related to high mortality rates and poor neurological outcomes. Anemia is prevalent among patients with post-cardiac arrest syndrome (PCAS), but its specific pathogenesis remains unclear. The mechanisms may involve various factors, including reduced production of erythropoietin, oxidative stress/inflammatory responses, gastrointestinal ischemic injury, hepcidin abnormalities, iatrogenic blood loss, and malnutrition. Measures to improve anemia related to cardiac arrest may include blood transfusions, administration of erythropoietin, anti-inflammation and antioxidant therapies, supplementation of hematopoietic materials, protection of gastrointestinal mucosa, and use of hepcidin antibodies and antagonists. Therefore, exploring the latest research progress on the mechanisms and treatment of anemia related to cardiac arrest is of significant guiding importance for improving secondary brain injury caused by anemia and the prognosis of patients with cardiac arrest.

Molecular Hydrogen Therapy-A Review on Clinical Studies and Outcomes

With its antioxidant properties, hydrogen gas (H2) has been evaluated in vitro, in animal studies and in human studies for a broad range of therapeutic indications. A simple search of "hydrogen gas" in various medical databases resulted in more than 2000 publications related to hydrogen gas as a potential new drug substance. A parallel search in clinical trial registers also generated many hits, reflecting the diversity in ongoing clinical trials involving hydrogen therapy. This review aims to assess and discuss the current findings about hydrogen therapy in the 81 identified clinical trials and 64 scientific publications on human studies. Positive indications have been found in major disease areas including cardiovascular diseases, cancer, respiratory diseases, central nervous system disorders, infections and many more. The available administration methods, which can pose challenges due to hydrogens' explosive hazards and low solubility, as well as possible future innovative technologies to mitigate these challenges, have been reviewed. Finally, an elaboration to discuss the findings is included with the aim of addressing the following questions: will hydrogen gas be a new drug substance in future clinical practice? If so, what might be the administration form and the clinical indications?

Evaluation of the safety and potential lipid-lowering effects of oral hydrogen-rich coral calcium (HRCC) capsules in patients with metabolic syndrome: a prospective case series study

Background

Metabolic syndrome is characterized by a cluster-like occurrence of conditions such as hypertension, hyperglycaemia, elevated low-density lipoprotein (LDL) cholesterol or triglycerides (TG) and high visceral fat. Metabolic syndrome is linked to the build-up of plaque within the artery, which leads to disorders of the circulatory, nervous and immune systems. A variety of treatments target the regulation of these conditions; nevertheless, they remain dominant risk factors for the development of type 2 diabetes (T2DM) and cardiovascular disease (CVD), which affect 26.9% of the US population. Management and intervention strategies for improving cholesterol and/or TG are worthwhile, and recent studies on hydrogen treatment are promising, particularly as molecular hydrogen is easily ingested. This study aimed to investigate the lipid-lowering effects and quality of life (QOL) improvement of hydrogen-rich coral calcium (HRCC) in patients with metabolic syndrome.

Methods

The patients, all Taiwanese, were randomly assigned to 3 different doses (low, medium, and high) of HRCC capsules. The primary outcome was the adverse effects/symptoms during this 4-week use of HRCC capsules. The secondary outcome was lipid profile changes. Complete blood count, inflammatory biomarkers, and QOL were also measured before and after the course of HRCC.

Results

Sixteen patients with metabolic syndrome completed this study (7 males, 9 females; mean age: 62 years; range: 32-80). No obvious adverse effects were recorded. Only changes in blood TG reached significance. The baseline TG value was 193.19 μL (SD = 107.44), which decreased to 151.75 μL (SD = 45.27) after 4 weeks of HRCC (p = 0.04). QOL showed no significant changes.

Conclusion

This study is the first human clinical trial evaluating HRCC capsules in patients with metabolic syndrome. Based on the safety and potential TG-lowering effects of short-term HRCC, further long-term investigations of HRCC are warranted.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT05196295].

Hydrogen Therapy and Its Future Prospects for Ameliorating COVID-19: Clinical Applications, Efficacy, and Modality

Molecular hydrogen is renowned as an odorless and colorless gas. The recommendations developed by China suggest that the inhalation of hydrogen molecules is currently advised in COVID-19 pneumonia treatment. The therapeutic effects of molecular hydrogens have been confirmed after numerous clinical trials and animal-model-based experiments, which have expounded that the low molecular weight of hydrogen enables it to easily diffuse and permeate through the cell membranes to produce a variety of biological impacts. A wide range of both chronic and acute inflammatory diseases, which may include sepsis, pancreatitis, respiratory disorders, autoimmune diseases, ischemia-reperfusion damages, etc. may be treated and prevented by using it. H₂ can primarily be inoculated through inhalation, by drinking water (which already contains H₂), or by administrating the injection of saline H₂ in the body. It may play a pivotal role as an antioxidant, in regulating the immune system, in anti-inflammatory activities (mitochondrial energy metabolism), and cell death (apoptosis, pyroptosis, and autophagy) by reducing the formation of excessive reactive O₂ species and modifying the transcription factors in the nuclei of the cells. However, the fundamental process of molecular hydrogen is still not entirely understood. Molecular hydrogen H₂ has a promising future in therapeutics based on its safety and possible usefulness. The current review emphasizes the antioxidative, anti-apoptotic, and anti-inflammatory effects of hydrogen molecules along with the underlying principle and fundamental mechanism involved, with a prime focus on the coronavirus disease of 2019 (COVID-19). This review will also provide strategies and recommendations for the therapeutic and medicinal applications of the hydrogen molecule.

Hydrogen therapy as a potential therapeutic intervention in heart disease: from the past evidence to future application

Cardiovascular disease is the leading cause of mortality worldwide. Excessive oxidative stress and inflammation play an important role in the development and progression of cardiovascular disease. Molecular hydrogen, a small colorless and odorless molecule, is considered harmless in daily life when its concentration is below 4% at room temperature. Owing to the small size of the hydrogen molecule, it can easily penetrate the cell membrane and can be metabolized without residue. Molecular hydrogen can be administered through inhalation, the drinking of hydrogen-rich water, injection with hydrogen-rich-saline, and bathing of an organ in a preservative solution. The utilization of molecular hydrogen has shown many benefits and can be effective for a wide range of purposes, from prevention to the treatment of diseases. It has been demonstrated that molecular hydrogen exerts antioxidant, anti-inflammatory, and antiapoptotic effects, leading to cardioprotective benefits. Nevertheless, the exact intracellular mechanisms of its action are still unclear. In this review, evidence of the potential benefits of hydrogen molecules obtained from in vitro, in vivo, and clinical investigations are comprehensively summarized and discussed with a focus on the cardiovascular aspects. The potential mechanisms involved in the protective effects of molecular hydrogen are also presented. These findings suggest that molecular hydrogen could be used as a novel treatment in various cardiovascular pathologies, including ischemic-reperfusion injury, cardiac injury from radiation, atherosclerosis, chemotherapy-induced cardiotoxicity, and cardiac hypertrophy.

Balance of the prooxidant and antioxidant system is associated with mortality in critically ill patients

It is well known that oxidative stress causes certain diseases and organ damage. However, roles of oxidative stress in the acute phase of critical patients remain to be elucidated. This study aimed to investigate the balance of oxidative and antioxidative system and to clarify the association between oxidative stress and mortality in critically ill patients. This cohort study enrolled 247 patients transported to our emergency department by ambulance. Blood was drawn on hospital arrival, and serum derivatives of reactive oxidant metabolites (dROMs, oxidative index) and biological antioxidant potential (BAP, antioxidative index) were measured. Modified ratio (MR) is also calculated as BAP/dROMs/7.51. There were 197 survivors and 50 non-survivors. In the non-survivors, dROMs were significantly lower (274 vs 311, p<0.01), BAP was significantly higher (2,853 vs 2,138, p<0.01), and MR was significantly higher (1.51 vs 0.92, p<0.01) compared to those in the survivors. The AUC of MR was similar to that for the APACHE II score. Contrary to our expectations, higher BAP and lower dROMs were observed on admission in non-survivors. This may suggest that the antioxidative system is more dominant in the acute phase of severe insults and that the balance toward a higher antioxidative system is associated with mortality.

Pharmacokinetics of hydrogen administered intraperitoneally as hydrogen-rich saline and its effect on ischemic neuronal cell death in the brain in gerbils

Intraperitoneal administration of hydrogen (H2)-containing saline inhibited neuronal cell death in ischemic stroke in a number of animal models, but it is unknown whether H2 is absorbed from the abdominal cavity into the blood and reaches the brain. In this study, we investigated whether intraperitoneal administration of saline containing H2 inhibits neuronal cell death caused by cerebral ischemia and measured the concentration of H2 in the carotid artery and inferior vena cava (IVC). Gerbils were subjected to transient unilateral cerebral ischemia twice, and saline or H2-rich saline was administered intraperitoneally three or seven times every 12 hours. We evaluated the number of apoptotic cells in the hippocampus and cerebral cortex on day 3 and the number of viable neurons in the hippocampus and cerebral cortex on day 7. In addition, a single dose of saline or H2-rich saline was administered intraperitoneally, and blood H2 levels in the carotid artery and IVC were measured. On day 3 of ischemia/reperfusion, the number of neurons undergoing apoptosis in the cortex was significantly lower in the H2-rich saline group than in the saline group, and on day 7, the number of viable neurons in the hippocampus and cerebral cortex was significantly higher in the H2-rich saline group. Intraperitoneal administration of H2-rich saline resulted in large increases in H2 concentration in the IVC ranging from 0.00183 mg/L (0.114%) to 0.00725 mg/L (0.453%). In contrast, carotid H2 concentrations remained in the range of 0.00008 mg/L (0.0049%) to 0.00023 (0.0146%). On average, H2 concentrations in carotid artery were 0.04 times lower than in IVC. These results indicate that intraperitoneal administration of H2-rich saline significantly suppresses neuronal cell death after cerebral ischemia, even though H2 hardly reaches the brain.

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].

Neutrophils and Neutrophil Extracellular Traps in Cardiovascular Disease: An Overview and Potential Therapeutic Approaches

Recent advances in pharmacotherapy have markedly improved the prognosis of cardiovascular disease (CVD) but have not completely conquered it. Therapies targeting the NOD-like receptor family pyrin domain containing 3 inflammasome and its downstream cytokines have proven effective in the secondary prevention of cardiovascular events, suggesting that inflammation is a target for treating residual risk in CVD. Neutrophil-induced inflammation has long been recognized as important in the pathogenesis of CVD. Circadian rhythm-related and disease-specific microenvironment changes give rise to neutrophil diversity. Neutrophils are primed by various stimuli, such as chemokines, cytokines, and damage-related molecular patterns, and the activated neutrophils contribute to the inflammatory response in CVD through degranulation, phagocytosis, reactive oxygen species generation, and the release of neutrophil extracellular traps (NETs). In particular, NETs promote immunothrombosis through the interaction with vascular endothelial cells and platelets and are implicated in the development of various types of CVD, such as acute coronary syndrome, deep vein thrombosis, and heart failure. NETs are promising candidates for anti-inflammatory therapy in CVD, and their efficacy has already been demonstrated in various animal models of the disease; however, they have yet to be clinically applied in humans. This narrative review discusses the diversity and complexity of neutrophils in the trajectory of CVD, the therapeutic potential of targeting NETs, and the related clinical issues.

Molecular Hydrogen Neuroprotection in Post-Ischemic Neurodegeneration in the Form of Alzheimer's Disease Proteinopathy: Underlying Mechanisms and Potential for Clinical Implementation-Fantasy or Reality?

Currently, there is a lot of public interest in naturally occurring substances with medicinal properties that are minimally toxic, readily available and have an impact on health. Over the past decade, molecular hydrogen has gained the attention of both preclinical and clinical researchers. The death of pyramidal neurons in especially the CA1 area of the hippocampus, increased permeability of the blood-brain barrier, neuroinflammation, amyloid accumulation, tau protein dysfunction, brain atrophy, cognitive deficits and dementia are considered an integral part of the phenomena occurring during brain neurodegeneration after ischemia. This review focuses on assessing the current state of knowledge about the neuroprotective effects of molecular hydrogen following ischemic brain injury. Recent studies in animal models of focal or global cerebral ischemia and cerebral ischemia in humans suggest that hydrogen has pleiotropic neuroprotective properties. One potential mechanism explaining some of the general health benefits of using hydrogen is that it may prevent aging-related changes in cellular proteins such as amyloid and tau protein. We also present evidence that, following ischemia, hydrogen improves cognitive and neurological deficits and prevents or delays the onset of neurodegenerative changes in the brain. The available evidence suggests that molecular hydrogen has neuroprotective properties and may be a new therapeutic agent in the treatment of neurodegenerative diseases such as neurodegeneration following cerebral ischemia with progressive dementia. We also present the experimental and clinical evidence for the efficacy and safety of hydrogen use after cerebral ischemia. The therapeutic benefits of gas therapy open up new promising directions in breaking the translational barrier in the treatment of ischemic stroke.

Direct and Indirect Methods for Studying Human Gut Microbiota

Aim: To review the main methods of intestinal microbiota studying.

Key points. Currently, molecular genetic methods are used mainly for basic research and do not have a unified protocol for data analysis, which makes it difficult to implement them in clinical practice. Measurement of short chain fatty acids (SCFA) concentrations in plasma provides the data, which can serve as an indirect biomarker of the colonic microbiota composition. However, currently available evidence is insufficient to relate the obtained values (SCFA levels and ratio) to a particular disease with a high degree of certainty. Trimethylamine N-oxide (TMAO) levels in the blood plasma and urine can also reflect the presence of specific bacterial clusters containing genes Cut, CntA/CntB and YeaW/YeaX. Therefore, further studies are required to reveal possible correlations between certain disorders and such parameters as the composition of gut microbiota, dietary patterns and TMAO concentration. Gas biomarkers, i.e. hydrogen, methane and hydrogen sulphide, have been studied in more detail and are better understood as compared to other biomarkers of the gut microbiome composition and functionality. The main advantage of gas biomarkers is that they can be measured multiple times using non-invasive techniques. These measurements provide information on the relative proportion of hydrogenic (i.e. hydrogen producing) and hydrogenotrophic (i.e. methanogenic and sulfate-reducing) microorganisms. In its turn, this opens up the possibility of developing new approaches to correction of individual microbiota components.

Conclusions. Integration of the data obtained by gut microbiota studies at the genome, transcriptome and metabolome levels would allow a comprehensive analysis of microbial community function and its interaction with the human organism. This approach may increase our understanding of the pathogenesis of various diseases as well open up new opportunities for prevention and treatment.

Hydrogen, a Novel Therapeutic Molecule, Regulates Oxidative Stress, Inflammation, and Apoptosis

Molecular hydrogen (H₂) is a colorless and odorless gas. Studies have shown that H₂ inhalation has the therapeutic effects in many animal studies and clinical trials, and its application is recommended in the novel coronavirus pneumonia treatment guidelines in China recently. H₂ has a relatively small molecular mass, which helps it quickly spread and penetrate cell membranes to exert a wide range of biological effects. It may play a role in the treatment and prevention of a variety of acute and chronic inflammatory diseases, such as acute pancreatitis, sepsis, respiratory disease, ischemia reperfusion injury diseases, autoimmunity diseases, etc.. H₂ is primarily administered via inhalation, drinking H₂-rich water, or injection of H₂ saline. It may participate in the anti-inflammatory and antioxidant activity (mitochondrial energy metabolism), immune system regulation, and cell death (apoptosis, autophagy, and pyroptosis) through annihilating excess reactive oxygen species production and modulating nuclear transcription factor. However, the underlying mechanism of H₂ has not yet been fully revealed. Owing to its safety and potential efficacy, H₂ has a promising potential for clinical use against many diseases. This review will demonstrate the role of H₂ in antioxidative, anti-inflammatory, and antiapoptotic effects and its underlying mechanism, particularly in coronavirus disease-2019 (COVID-19), providing strategies for the medical application of H₂ for various diseases.

Upregulation of hemeoxygenase enzymes HO-1 and HO-2 following ischemia-reperfusion injury in connection with experimental cardiac arrest and cardiopulmonary resuscitation: Neuroprotective effects of methylene blue

Oxidative stress plays an important role in neuronal injuries after cardiac arrest. Increased production of carbon monoxide (CO) by the enzyme hemeoxygenase (HO) in the brain is induced by the oxidative stress. HO is present in the CNS in two isoforms, namely the inducible HO-1 and the constitutive HO-2. Elevated levels of serum HO-1 occurs in cardiac arrest patients and upregulation of HO-1 in cardiac arrest is seen in the neurons. However, the role of HO-2 in cardiac arrest is not well known. In this review involvement of HO-1 and HO-2 enzymes in the porcine brain following cardiac arrest and resuscitation is discussed based on our own observations. In addition, neuroprotective role of methylene blue- an antioxidant dye on alterations in HO under in cardiac arrest is also presented. The biochemical findings of HO-1 and HO-2 enzymes using ELISA were further confirmed by immunocytochemical approach to localize selective regional alterations in cardiac arrest. Our observations are the first to show that cardiac arrest followed by successful cardiopulmonary resuscitation results in significant alteration in cerebral concentrations of HO-1 and HO-2 levels indicating a prominent role of CO in brain pathology and methylene blue during CPR followed by induced hypothermia leading to superior neuroprotection after return of spontaneous circulation (ROSC), not reported earlier.

Mechanism of hydrogen on cervical cancer suppression revealed by high‑throughput RNA sequencing

Cervical cancer is considered one of the diseases with the highest mortality among women and with limited treatment options. Hydrogen (H₂) inhalation has been reported to have a variety of tumor-suppressive effects, but the exact mechanism remains unclear. In the present study, HeLa cervical cancer cells and HaCaT keratinocytes treated with H₂, and a HeLa xenograft mouse model subjected to H₂ inhalation were established. TUNEL, Cell Counting Kit-8 and Ki67 staining assays were used to detect cell apoptosis and proliferation. Oxidative stress was determined according to the levels of reactive oxygen species, malondialdehyde and superoxide dismutase. Tumor growth was recorded every 3 days, and the excised tumors were stained with hematoxylin and eosin. High-throughput RNA sequencing and subsequent Gene Ontology (GO) enrichment analysis were performed in HeLa-treated and un-treated HeLa cells. The expression of hypoxia-inducible factor (HIF)-1α and NF-κB p65 was verified by western blotting, immunohistochemistry and reverse transcription-quantitative PCR. The results revealed an increased apoptosis rate, and reduced cell proliferation and oxidative stress in H₂-treated HeLa cells but not in HaCaT cells. Similarly, decreased tumor growth and cell proliferation, and enhanced cell apoptosis were observed in H₂-treated HeLa tumors. RNA sequencing and GO analysis suggest that downregulated HIF1A (HIF-1α mRNA) and RelA (NF-κB p65) levels, and reduced NF-κB signaling were associated with the antitumor effect of H₂. Finally, decreased HIF-1α and NF-κB p65 expression both at the transcriptional and translational levels were observed in H₂-treated HeLa cells and in HeLa-derived tumors. In conclusion, the present study reveals a novel mechanism of H₂ against cervical cancer, which may serve as a potential therapeutic target in clinical practice.

Protective effects of hydrogen gas against spinal cord ischemia-reperfusion injury

OBJECTIVE

This experimental study aimed to assess the efficacy of hydrogen gas inhalation against spinal cord ischemia-reperfusion injury and reveal its mechanism by measuring glutamate concentration in the ventral horn using an in vivo microdialysis method.

METHODS

Male Sprague-Dawley rats were divided into the following 6 groups: sham, only spinal ischemia, 3% hydrogen gas (spinal ischemia + 3% hydrogen gas), 2% hydrogen gas (spinal ischemia + 2% hydrogen gas), 1% hydrogen gas (spinal ischemia + 1% hydrogen gas), and hydrogen gas dihydrokainate (spinal ischemia + dihydrokainate [selective inhibitor of glutamate transporter-1] + 3% hydrogen gas). Hydrogen gas inhalation was initiated 10 minutes before the ischemia. For the hydrogen gas dihydrokainate group, glutamate transporter-1 inhibitor was administered 20 minutes before the ischemia. Immunofluorescence was performed to assess the expression of glutamate transporter-1 in the ventral horn.

RESULTS

The increase in extracellular glutamate induced by spinal ischemia was significantly suppressed by 3% hydrogen gas inhalation (P < .05). This effect was produced in increasing order: 1%, 2%, and 3%. Conversely, the preadministration of glutamate transporter-1 inhibitor diminished the suppression of spinal ischemia-induced glutamate increase observed during the inhalation of 3% hydrogen gas. Immunofluorescence indicated the expression of glutamate transporter-1 in the spinal ischemia group was significantly decreased compared with the sham group, which was attenuated by 3% hydrogen gas inhalation (P < .05).

CONCLUSIONS

Our study demonstrated hydrogen gas inhalation exhibits a protective and concentration-dependent effect against spinal ischemic injury, and glutamate transporter-1 has an important role in the protective effects against spinal cord injury.

Hydrogen Is Promising for Medical Applications

Hydrogen (H2) is promising as an energy source for the next generation. Medical applications using H2 gas can be also considered as a clean and economical technology. Since the H2 gas based on electrolysis of water production has potential to expand the medical applications, the technology has been developed in order to safely dilute it and to supply it to the living body by inhalation, respectively. H2 is an inert molecule which can scavenge the highly active oxidants including hydroxyl radical (·OH) and peroxynitrite (ONOO−), and which can convert them into water. H2 is clean and causes no adverse effects in the body. The mechanism of H2 is different from that of traditional drugs because it works on the root of many diseases. Since H2 has extensive and various effects, it may be called a “wide spectrum molecule” on diseases. In this paper, we reviewed the current medical applications of H2 including its initiation and development, and we also proposed its prospective medical applications. Due to its marked efficacy and no adverse effects, H2 will be a next generation therapy candidate for medical applications.