Hydrogen therapy may reduce the risks related to radiation-induced oxidative stress in space flight

A more accurate indicator to evaluate oxidative stress in rat plasma with osteoporosis

Background: oxidative stress is linked to various human diseases which developed into the idea of "disrupted redox signaling". Osteoporosis (OP) is a chronic skeletal disorder characterized by low bone mineral density and deterioration of bone microarchitecture among which estrogen deficiency is the main cause. Lack of estrogen leads to the imbalance between oxidation and anti-oxidation in patients, and oxidative stress is an important link in the pathogenesis of OP. The ratio of the reduced to the oxidized thiols can characterize the redox status. However, few methods have been reported for the simultaneous determination of reduced forms and their oxidized forms of thiols in plasma. Methods: we developed a hollow fiber centrifugal ultrafiltration (HFCF-UF) method for sample preparation and validated a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method to determine two reduced forms of thiols-homocysteine (Hcy), cysteine (Cys) levels and their respective oxidized compounds, homocystine (HHcy) and cystine (Cyss) in rat plasma simultaneously for the first time. Thirty-six female rats were randomly divided into three groups: normal control (NC), oxidative stress (ovariectomy, OVX) and ovariectomy with hydrogen-rich saline administration (OVX + HRS). Results: the validation parameters for the methodological results were within the acceptance criteria. There were both significant differences of Hcy/HHcy (Hcy reduced/oxidized) and Cys/Cyss (Cys reduced/oxidized) in rat plasma between three groups with both p < 0.05 and meanwhile, the p values of malondialdehyde, superoxide dismutase and glutathione peroxidase were all less than 0.01. The value of both Hcy/HHcy and Cys/Cyss were significantly decreased with the change of Micro-CT scan result of femoral neck in OVX group (both the trabecular thickness and trabecular number significantly decreased with a significant increase of trabecular separation) which demonstrate OP occurs. The change of Hcy/HHcy is more obvious and prominent than Cys/Cyss. Conclusions: the Hcy/HHcy and Cys/Cyss could be suitable biomarkers for oxidative stress and especially Hcy/HHcy is more sensitive. The developed method is simple and accurate. It can be easily applied in clinical research to further evaluate the oxidative stress indicator for disease risk factors.

Myocardial Disease and Long-Distance Space Travel: Solving the Radiation Problem

Radiation-induced cardiovascular disease is a well-known complication of radiation exposure. Over the last few years, planning for deep space missions has increased interest in the effects of space radiation on the cardiovascular system, as an increasing number of astronauts will be exposed to space radiation for longer periods of time. Research has shown that exposure to different types of particles found in space radiation can lead to the development of diverse cardiovascular disease via fibrotic myocardial remodeling, accelerated atherosclerosis and microvascular damage. Several underlying mechanisms for radiation-induced cardiovascular disease have been identified, but many aspects of the pathophysiology remain unclear. Existing pharmacological compounds have been evaluated to protect the cardiovascular system from space radiation-induced damage, but currently no radioprotective compounds have been approved. This review critically analyzes the effects of space radiation on the cardiovascular system, the underlying mechanisms and potential countermeasures to space radiation-induced cardiovascular disease.

Hydrogen-rich water alleviates cyclosporine A-induced nephrotoxicity via the Keap1/Nrf2 signaling pathway

Oxidative stress induced by long-term cyclosporine A (CsA) administration is a major cause of chronic nephrotoxicity, which is characterized by tubular atrophy, tubular cell apoptosis, and interstitial fibrosis in the progression of organ transplantation. Although hydrogen-rich water (HRW) has been used to prevent various oxidative stress-related diseases, its underlying mechanisms remain unclear. This study investigated the effects of HRW on CsA-induced nephrotoxicity and its potential mechanisms. After administration of CsA (25 mg/kg/day), rats were treated with or without HRW (12 mL/kg) for 4 weeks. Renal function and vascular activity were investigated. Histological changes in kidney tissues were analyzed using Masson's trichrome and terminal deoxynucleotidyl transferase dUTP nick-end labeling stains. Oxidative stress markers and the activation of the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway were also measured. We found that CsA increased the levels of reactive oxygen species (ROS) and malonaldehyde (MDA), but it reduced glutathione (GSH) and superoxide dismutase (SOD) levels. Such alterations induced vascular dysfunction, tubular atrophy, interstitial fibrosis, and tubular apoptosis. This was evident secondary to an increase in urinary protein, serum creatinine, and blood urea nitrogen, ultimately leading to renal dysfunction. Conversely, HRW decreased levels of ROS and MDA while increasing the activity of GSH and SOD. This was accompanied by an improvement in vascular and renal function. Moreover, HRW significantly decreased the level of Keap1 and increased the expression of Nrf2, NADPH dehydrogenase quinone 1, and heme oxygenase 1. In conclusion, HRW restored the balance of redox status, suppressed oxidative stress damage, and improved kidney function induced by CsA via activation of the Keap1/Nrf2 signaling pathway.

Effects of Iron Overload and Oxidative Damage on the Musculoskeletal System in the Space Environment: Data from Spaceflights and Ground-Based Simulation Models

The space environment chiefly includes microgravity and radiation, which seriously threatens the health of astronauts. Bone loss and muscle atrophy are the two most significant changes in mammals after long-term residency in space. In this review, we summarized current understanding of the effects of microgravity and radiation on the musculoskeletal system and discussed the corresponding mechanisms that are related to iron overload and oxidative damage. Furthermore, we enumerated some countermeasures that have a therapeutic potential for bone loss and muscle atrophy through using iron chelators and antioxidants. Future studies for better understanding the mechanism of iron and redox homeostasis imbalance induced by the space environment and developing the countermeasures against iron overload and oxidative damage consequently may facilitate human to travel more safely in space.

Hydrogen-rich saline prevents bone loss in diabetic rats induced by streptozotocin

PURPOSE

As an antioxidant molecule, hydrogen has been received much more attention and reported to be used as the treatment strategy for various diseases. In this study, we hypothesize that systemic delivery of hydrogen saline water may improve the reservation of bone tissue in the tibias and femurs of osteoporotic rats caused by diabetes mellitus (DM), which is characterized by increased levels of oxidative stress and overproducing reactive oxygen species (ROS).

METHODS

The animals were divided into three groups of 12 animals and lavaged with normal saline (normal control and DM), or hydrogen saline water (DM + HRS). General status, blood glucose level, tibial and femoral mechanical strength, and micro-CT scans of the proximal tibia were recorded and analyzed.

RESULTS

After 12 weeks, the glucose level was significantly decreased in the DM + HRS group compared with that of the DM group. Micro-CT scans showed that bone volume/total volume, connectivity density, trabecular thickness, and trabecular number were significantly increased compared with the DM group. Mechanical results of energy, stiffness and elastic modulus in the DM + HRS group were significantly higher than in the other groups for the tibia and femur.

CONCLUSIONS

The results indicate that the systemic delivery of hydrogen saline water, which is safe and well tolerated, preserves bone volume and decreases fracture risks in streptozotocin-induced diabetic status rats, whose bone structure or inherent material properties of bone tissues are changed.

Preventive and therapeutic application of molecular hydrogen in situations with excessive production of free radicals

Excessive production of oxygen free radicals has been regarded as a causative common denominator of many pathological processes in the animal kingdom. Hydroxyl and nitrosyl radicals represent the major cause of the destruction of biomolecules either by a direct reaction or by triggering a chain reaction of free radicals. Scavenging of free radicals may act preventively or therapeutically. A number of substances that preferentially react with free radicals can serve as scavengers, thus increasing the internal capacity/activity of endogenous antioxidants and protecting cells and tissues against oxidative damage. Molecular hydrogen (H(2)) reacts with strong oxidants, such as hydroxyl and nitrosyl radicals, in the cells, that enables utilization of its potential for preventive and therapeutic applications. H(2) rapidly diffuses into tissues and cells without affecting metabolic redox reactions and signaling reactive species. H(2) reduces oxidative stress also by regulating gene expression, and functions as an anti-inflammatory and anti-apoptotic agent. There is a growing body of evidence based on the results of animal experiments and clinical observations that H(2) may represent an effective antioxidant for the prevention of oxidative stress-related diseases. Application of molecular hydrogen in situations with excessive production of free radicals, in particular, hydroxyl and nitrosyl radicals is relatively simple and effective, therefore, it deserves special attention.

Hydrogen water reduces NSE, IL-6, and TNF-α levels in hypoxic-ischemic encephalopathy

This study retrospectively analyzed the efficacy of hydrogen water in the treatment of neonatal hypoxic-ischemic encephalopathy (HIE) and its effect on serum neuron-specific enolase (NSE), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels.

Forty newborns with HIE who received treatment from April 2014 to April 2015 were divided into a conventional care group and a hydrogen water group according to the different treatment methods applied. Twenty healthy full-term newborns comprised the control group. In the hydrogen water group, 5-mL/kg hydrogen water was orally administered two days after birth daily for 10 days in addition to conventional treatment. After 10 days, efficacy indicators were examined in the HIE groups. The NSE, IL-6, and TNF-α levels were compared among all three groups.

The efficacy indicators were significantly lower in the hydrogen water group compared with the conventional group. Before treatment, the serum NSE, IL-6, and TNF-α levels in the HIE groups were higher than those in the control group. After treatment, these levels in the hydrogen water group were lower than those in the conventional group.

Hydrogen water lowers serum NSE, IL-6, and TNF-α levels in HIE newborns, thereby exerting a protective effect.

ROS-Induced Nuclear Translocation of Calpain-2 Facilitates Cardiomyocyte Apoptosis in Tail-Suspended Rats

Isoproterenol (ISO) induced nuclear translocation of calpain-2 which further increased susceptibility of cardiomyocyte apoptosis in tail-suspended rats. The underlying mechanisms remain elusive. In the present study, the results showed that ISO (10 nM) significantly elevated NADPH oxidases (NOXs) activity and NOXs-derived ROS productions which induced nuclear translocation of calpain-2 in cardiomyocytes of tail-suspended rats. In contrast, the inhibition of NADPH oxidase or cleavage of ROS not only reduced ROS productions, but also resisted nuclear translocation of calpain-2 and decreased ISO-induced apoptosis of cardiomyocyte in tail-suspended rats. ISO also increased the constitutive binding between calpain-2 and Ca(2+)/calmodulin-dependent protein kinase II δB (CaMK II δB) in nuclei, concomitant with the promotion of CaMK II δB degradation and subsequent down-regulation of Bcl-2 mRNA expression and the ratio of Bcl-2 to Bax protein in tail-suspended rat cardiomyocytes. These effects of ISO on cardiomyocytes were abolished by a calpain inhibitor PD150606. Inhibition of calpain significantly reduced ISO-induced loss of the mitochondrial membrane potential, cytochrome c release into the cytoplasm, as well as the activation of caspase-3 and caspase-9 in mitochondrial apoptotic pathway. In summary, the above results suggest that ISO increased NOXs-derived ROS which activated nuclear translocation of calpain-2, subsequently nuclear calpain-2 degraded CaMK II δB which reduced the ratio of Bcl-2 to Bax, and finally the mitochondria apoptosis pathway was triggered in tail-suspended rat cardiomyocytes. Therefore, calpain-2 may represent a potentially therapeutic target for prevention of oxidative stress-associated cardiomyocyte apoptosis.

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

Molecular hydrogen (H2) was believed to be inert and nonfunctional in mammalian cells. We overturned this concept by demonstrating that H2 reacts with highly reactive oxidants such as hydroxyl radical ((•)OH) and peroxynitrite (ONOO(-)) inside cells. H2 has several advantages exhibiting marked effects for medical applications: it is mild enough neither to disturb metabolic redox reactions nor to affect signaling by reactive oxygen species. Therefore, it should have no or little adverse effects. H2 can be monitored with an H2-specific electrode or by gas chromatography. H2 rapidly diffuses into tissues and cells to exhibit efficient effects. Thus, we proposed the potential of H2 for preventive and therapeutic applications. There are several methods to ingest or consume H2: inhaling H2 gas, drinking H2-dissolved water (H2-water), injecting H2-dissolved saline (H2-saline), taking an H2 bath, or dropping H2-saline onto the eyes. Recent publications revealed that, in addition to the direct neutralization of highly reactive oxidants, H2 indirectly reduces oxidative stress by regulating the expression of various genes. Moreover, by regulating gene expression, H2 functions as an anti-inflammatory, antiallergic, and antiapoptotic molecule, and stimulates energy metabolism. In addition to growing evidence obtained by model animal experiments, extensive clinical examinations were performed or are under way. Since most drugs specifically act on their specific targets, H2 seems to differ from conventional pharmaceutical drugs. Owing to its great efficacy and lack of adverse effects, H2 has potential for clinical applications for many diseases.

Beneficial effects of cellular autofluorescence following ionization radiation: hypothetical approaches for radiation protection and enhancing radiotherapy effectiveness

Ionization radiation (IR) is a main part of modern technologies with a double-edge sword manner. Finding the most feasible therapies to reduce adverse effects of IR and also enhancing radiotherapy effectiveness is a debating issue that has been challenged and studied for years. The main aim of the present hypothetical research was to theorize and suggest a new biological radiation protection approach and also increasing radiotherapy outcomes based on cellular autofluorescence following IR. In this hypothesis, we suggested that this cellular autofluorescence can activate some synthetic drugs called photo-activated agents that are injected in human body after radiation exposures scenarios. Photo activated agents can activate biological pathways such as DNA repair and immunostimulation pathways, bystander signals blocking, and so survive cells and tissues. In the other hand, light emitted by cellular response to radiation can be used as like as photodynamic therapy and therefore more cancer cells killing via apoptosis and necrosis. These ideas can be performed in future using more animal and in vivo/in vitro studies and clinical trials. In conclusion, cellular autofluorescence after radiation exposure can be used as a source for activation specific drugs for radiation protection and also radiation therapy effectiveness. These hypothetical therapeutic approaches can be served as personalized therapy based on individual radiosensitivity.

Molecular hydrogen as a preventive and therapeutic medical gas: initiation, development and potential of hydrogen medicine

Molecular hydrogen (H2) has been accepted to be an inert and nonfunctional molecule in our body. We have turned this concept by demonstrating that H2 reacts with strong oxidants such as hydroxyl radical in cells, and proposed its potential for preventive and therapeutic applications. H2 has a number of advantages exhibiting extensive effects: H2 rapidly diffuses into tissues and cells, and it is mild enough neither to disturb metabolic redox reactions nor to affect signaling reactive oxygen species; therefore, there should be no or little adverse effects of H2. There are several methods to ingest or consume H2; inhaling H2 gas, drinking H2-dissolved water (H2-water), injecting H2-dissolved saline (H2-saline), taking an H2 bath, or dropping H2-saline into the eyes. The numerous publications on its biological and medical benefits revealed that H2 reduces oxidative stress not only by direct reactions with strong oxidants, but also indirectly by regulating various gene expressions. Moreover, by regulating the gene expressions, H2 functions as an anti-inflammatory and anti-apoptotic, and stimulates energy metabolism. In addition to growing evidence obtained by model animal experiments, extensive clinical examinations were performed or are under investigation. Since most drugs specifically act to their targets, H2 seems to differ from conventional pharmaceutical drugs. Owing to its great efficacy and lack of adverse effects, H2 has promising potential for clinical use against many diseases.

Oral 'hydrogen water' induces neuroprotective ghrelin secretion in mice

The therapeutic potential of molecular hydrogen (H₂) is emerging in a number of human diseases and in their animal models, including in particular Parkinson's disease (PD). H₂ supplementation of drinking water has been shown to exert disease-modifying effects in PD patients and neuroprotective effects in experimental PD model mice. However, H₂ supplementation does not result in detectable changes in striatal H₂ levels, indicating an indirect effect. Here we show that H₂ supplementation increases gastric expression of mRNA encoding ghrelin, a growth hormone secretagogue, and ghrelin secretion, which are antagonized by the β₁-adrenoceptor blocker, atenolol. Strikingly, the neuroprotective effect of H₂ water was abolished by either administration of the ghrelin receptor-antagonist, D-Lys³ GHRP-6, or atenolol. Thus, the neuroprotective effect of H₂ in PD is mediated by enhanced production of ghrelin. Our findings point to potential, novel strategies for ameliorating pathophysiology in which a protective effect of H₂ supplementation has been demonstrated.

Hydrogen as a new class of radioprotective agent

It is well known that most of the ionizing radiation-induced damage is caused by hydroxyl radicals (·OH) follows radiolysis of H2O. Molecular hydrogen (H2) has antioxidant activities by selectively reducing ·OH and peroxynitrite(ONOO-). We firstly hypothesized and demonstrated the radioprotective effect of H2 in vitro and in vivo, which was also repeated on different experimental animal models by different departments. A randomized, placebo-controlled study showed that consumption of hydrogen-rich water reduces the biological reaction to radiation-induced oxidative stress without compromising anti-tumor effects. These encouraging results suggested that H2 represents a potentially novel preventative strategy for radiation-induced oxidative injuries. H2 is explosive. Therefore, administration of hydrogen-rich solution (physiological saline/pure water/other solutions saturated with H2) may be more practical in daily life and more suitable for daily consumption. This review focuses on major scientific and clinical advances of hydrogen-rich solution/H2 as a new class of radioprotective agent.

Microgravity induces pelvic bone loss through osteoclastic activity, osteocytic osteolysis, and osteoblastic cell cycle inhibition by CDKN1a/p21

Bone is a dynamically remodeled tissue that requires gravity-mediated mechanical stimulation for maintenance of mineral content and structure. Homeostasis in bone occurs through a balance in the activities and signaling of osteoclasts, osteoblasts, and osteocytes, as well as proliferation and differentiation of their stem cell progenitors. Microgravity and unloading are known to cause osteoclast-mediated bone resorption; however, we hypothesize that osteocytic osteolysis, and cell cycle arrest during osteogenesis may also contribute to bone loss in space. To test this possibility, we exposed 16-week-old female C57BL/6J mice (n = 8) to microgravity for 15-days on the STS-131 space shuttle mission. Analysis of the pelvis by µCT shows decreases in bone volume fraction (BV/TV) of 6.29%, and bone thickness of 11.91%. TRAP-positive osteoclast-covered trabecular bone surfaces also increased in microgravity by 170% (p = 0.004), indicating osteoclastic bone degeneration. High-resolution X-ray nanoCT studies revealed signs of lacunar osteolysis, including increases in cross-sectional area (+17%, p = 0.022), perimeter (+14%, p = 0.008), and canalicular diameter (+6%, p = 0.037). Expression of matrix metalloproteinases (MMP) 1, 3, and 10 in bone, as measured by RT-qPCR, was also up-regulated in microgravity (+12.94, +2.98 and +16.85 fold respectively, p<0.01), with MMP10 localized to osteocytes, and consistent with induction of osteocytic osteolysis. Furthermore, expression of CDKN1a/p21 in bone increased 3.31 fold (p<0.01), and was localized to osteoblasts, possibly inhibiting the cell cycle during tissue regeneration as well as conferring apoptosis resistance to these cells. Finally the apoptosis inducer Trp53 was down-regulated by −1.54 fold (p<0.01), possibly associated with the quiescent survival-promoting function of CDKN1a/p21. In conclusion, our findings identify the pelvic and femoral region of the mouse skeleton as an active site of rapid bone loss in microgravity, and indicate that this loss is not limited to osteoclastic degradation. Therefore, this study offers new evidence for microgravity-induced osteocytic osteolysis, and CDKN1a/p21-mediated osteogenic cell cycle arrest.

Hydrogen-rich medium suppresses the generation of reactive oxygen species, elevates the Bcl-2/Bax ratio and inhibits advanced glycation end product-induced apoptosis

The purpose of the present study was to determine whether using hydrogen-rich medium (HRM) to increase hydrogen levels in endothelial cells (ECs) protects ECs from apoptosis induced by advanced glycation end products (AGEs). The thoracic aorta was removed from 2-3-year-old Sprague-Dawley rats, and ECs were isolated and cultured. After culturing ECs in the presence of AGEs and/or with HRM for 24 h, Annexin V/7-AAD and TUNEL staining were carried out to detect apoptosis. Intracellular ROS were detected by fluorescent probe and quantified by flow cytometry. The expression of antioxidative enzymes (superoxide dismutase, glutathione peroxidase) was determined by real-time PCR analysis and enzymatic assay. The relative expression levels of Bcl-2 and Bax were analyzed by western blotting. The addition of AGEs increased the apoptosis of ECs in a concentration-dependent manner and HRM reduced the AGE (400 µg/ml)-induced apoptosis from 21.61±2.52 to 11.32±1.75%. HRM also significantly attenuated the AGE-induced intracellular ROS induction and decrease in the expression of antioxidative enzymes. In conclusion, hydrogen exhibits significant protective effects against AGE-induced EC injury possibly through reducing ROS generation, intracellular antioxidant enzyme system protection and elevation of the Bcl-2/Bax ratio.

Recent progress toward hydrogen medicine: potential of molecular hydrogen for preventive and therapeutic applications

Persistent oxidative stress is one of the major causes of most lifestyle-related diseases, cancer and the aging process. Acute oxidative stress directly causes serious damage to tissues. Despite the clinical importance of oxidative damage, antioxidants have been of limited therapeutic success. We have proposed that molecular hydrogen (H₂) has potential as a “novel” antioxidant in preventive and therapeutic applications [Ohsawa et al., Nat Med. 2007: 13; 688-94]. H₂ has a number of advantages as a potential antioxidant: H₂ rapidly diffuses into tissues and cells, and it is mild enough neither to disturb metabolic redox reactions nor to affect reactive oxygen species (ROS) that function in cell signaling, thereby, there should be little adverse effects of consuming H₂. There are several methods to ingest or consume H₂, including inhaling hydrogen gas, drinking H₂-dissolved water (hydrogen water), taking a hydrogen bath, injecting H₂-dissolved saline (hydrogen saline), dropping hydrogen saline onto the eye, and increasing the production of intestinal H₂ by bacteria. Since the publication of the first H₂ paper in Nature Medicine in 2007, the biological effects of H₂ have been confirmed by the publication of more than 38 diseases, physiological states and clinical tests in leading biological/medical journals, and several groups have started clinical examinations. Moreover, H₂ shows not only effects against oxidative stress, but also various anti-inflammatory and anti-allergic effects. H₂ regulates various gene expressions and protein-phosphorylations, though the molecular mechanisms underlying the marked effects of very small amounts of H₂ remain elusive.

A hypothesis on biological protection from space radiation through the use of new therapeutic gases as medical counter measures

Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is biological damage that is associated with increased oxidative stress. It is therefore important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as chemical radioprotectors for radical scavenging and as biological signaling molecules for management of the body's response to exposure. From reviewing radiochemistry of water, biological effects of CO, H₂, NO, and H₂S gas, and mechanisms of radiation biology, it can be concluded that this approach may have therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion (IR) injury, acute respiratory distress syndrome, Parkinson's and Alzheimer's disease, cataracts, and aging. We envision applying these therapies through inhalation of gas mixtures or ingestion of water with dissolved gases.