Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals

Acute oxidative stress induced by ischemia-reperfusion or inflammation causes serious damage to tissues, and persistent oxidative stress is accepted as one of the causes of many common diseases including cancer. We show here that hydrogen (H(2)) has potential as an antioxidant in preventive and therapeutic applications. We induced acute oxidative stress in cultured cells by three independent methods. H(2) selectively reduced the hydroxyl radical, the most cytotoxic of reactive oxygen species (ROS), and effectively protected cells; however, H(2) did not react with other ROS, which possess physiological roles. We used an acute rat model in which oxidative stress damage was induced in the brain by focal ischemia and reperfusion. The inhalation of H(2) gas markedly suppressed brain injury by buffering the effects of oxidative stress. Thus H(2) can be used as an effective antioxidant therapy; owing to its ability to rapidly diffuse across membranes, it can reach and react with cytotoxic ROS and thus protect against oxidative damage.

Consumption of hydrogen water prevents atherosclerosis in apolipoprotein E knockout mice

Oxidative stress is implicated in atherogenesis; however most clinical trials with dietary antioxidants failed to show marked success in preventing atherosclerotic diseases. We have found that hydrogen (dihydrogen; H(2)) acts as an effective antioxidant to reduce oxidative stress [I. Ohsawa, M. Ishikawa, K. Takahashi, M. Watanabe, K. Nishimaki, K. Yamagata, K. Katsura, Y. Katayama, S, Asoh, S. Ohta, Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals, Nat. Med. 13 (2007) 688-694]. Here, we investigated whether drinking H(2)-dissolved water at a saturated level (H(2)-water) ad libitum prevents arteriosclerosis using an apolipoprotein E knockout mouse (apoE(-/-)), a model of the spontaneous development of atherosclerosis. ApoE(-/-) mice drank H(2)-water ad libitum from 2 to 6 month old throughout the whole period. Atherosclerotic lesions were significantly reduced by ad libitum drinking of H(2)-water (p=0.0069) as judged by Oil-Red-O staining series of sections of aorta. The oxidative stress level of aorta was decreased. Accumulation of macrophages in atherosclerotic lesions was confirmed. Thus, consumption of H(2)-dissolved water has the potential to prevent arteriosclerosis.

Molecular hydrogen improves obesity and diabetes by inducing hepatic FGF21 and stimulating energy metabolism in db/db mice

Recent extensive studies have revealed that molecular hydrogen (H(2)) has great potential for improving oxidative stress-related diseases by inhaling H(2) gas, injecting saline with dissolved H(2), or drinking water with dissolved H(2) (H(2)-water); however, little is known about the dynamic movement of H(2) in a body. First, we show that hepatic glycogen accumulates H(2) after oral administration of H(2)-water, explaining why consumption of even a small amount of H(2) over a short span time efficiently improves various disease models. This finding was supported by an in vitro experiment in which glycogen solution maintained H(2). Next, we examined the benefit of ad libitum drinking H(2)-water to type 2 diabetes using db/db obesity model mice lacking the functional leptin receptor. Drinking H(2)-water reduced hepatic oxidative stress, and significantly alleviated fatty liver in db/db mice as well as high fat-diet-induced fatty liver in wild-type mice. Long-term drinking H(2)-water significantly controlled fat and body weights, despite no increase in consumption of diet and water. Moreover, drinking H(2)-water decreased levels of plasma glucose, insulin, and triglyceride, the effect of which on hyperglycemia was similar to diet restriction. To examine how drinking H(2)-water improves obesity and metabolic parameters at the molecular level, we examined gene-expression profiles, and found enhanced expression of a hepatic hormone, fibroblast growth factor 21 (FGF21), which functions to enhance fatty acid and glucose expenditure. Indeed, H(2) stimulated energy metabolism as measured by oxygen consumption. The present results suggest the potential benefit of H(2) in improving obesity, diabetes, and metabolic syndrome.

Molecular hydrogen regulates gene expression by modifying the free radical chain reaction-dependent generation of oxidized phospholipid mediators

We previously showed that H2 acts as a novel antioxidant to protect cells against oxidative stress. Subsequently, numerous studies have indicated the potential applications of H2 in therapeutic and preventive medicine. Moreover, H2 regulates various signal transduction pathways and the expression of many genes. However, the primary targets of H2 in the signal transduction pathways are unknown. Here, we attempted to determine how H2 regulates gene expression. In a pure chemical system, H2 gas (approximately 1%, v/v) suppressed the autoxidation of linoleic acid that proceeds by a free radical chain reaction, and pure 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine (PAPC), one of the major phospholipids, was autoxidized in the presence or absence of H2. H2 modified the chemical production of the autoxidized phospholipid species in the cell-free system. Exposure of cultured cells to the H2-dependently autoxidized phospholipid species reduced Ca(2+) signal transduction and mediated the expression of various genes as revealed by comprehensive microarray analysis. In the cultured cells, H2 suppressed free radical chain reaction-dependent peroxidation and recovered the increased cellular Ca(2+), resulting in the regulation of Ca(2+)-dependent gene expression. Thus, H2 might regulate gene expression via the Ca(2+) signal transduction pathway by modifying the free radical-dependent generation of oxidized phospholipid mediators.

Protective Effect of Hydrogen Gas Inhalation on Muscular Damage using a Mouse Hind Limb Ischemia Reperfusion Injury Model

Background: Ischemia-reperfusion injury is one of the leading causes of tissue damage and dysfunction, in particular, free tissue transfer, traumatically amputated extremity, and prolonged tourniquet application during extremity surgery. In this study, the authors investigated the therapeutic effects of hydrogen gas on skeletal muscle ischemia-reperfusion injury. Methods: The authors compared the concentration of hydrogen in a muscle on intraperitoneal administration of hydrogen-rich saline and on inhalation of hydrogen gas. Animals were subjected to ischemia-reperfusion. Mice were treated with inhalation of hydrogen gas, and the hind gastrocnemius muscle was collected. Muscle morphology and inflammatory change were evaluated after ischemia-reperfusion. Moreover, a footprint test was performed to assess the functional effect of hydrogen. Results: Hydrogen concentration of tissue was significantly higher, and the elevated level was maintained longer by hydrogen gas inhalation than by intraperitoneal administration of hydrogen-rich saline. Infarct zone and area with loss of tissue structure and marked cellular infiltration were significantly decreased in groups treated by hydrogen gas inhalation during ischemia-reperfusion; however, these effects were not observed by posttreatment of hydrogen. One week after ischemia-reperfusion, mice that had been pretreated with hydrogen gas recovered faster and achieved smoother walking in appearance compared with mice in the other groups as assessed by the footprint test. Conclusions: Inhalation of hydrogen gas attenuates muscle damage, inhibits inflammatory response, and enhances functional recovery. These findings suggest that the optimal route for hydrogen delivery is continuous inhalation of hydrogen gas, which could be a novel clinical mode of treatment in ischemia-reperfusion injury.

Effects of Molecular Hydrogen Assessed by an Animal Model and a Randomized Clinical Study on Mild Cognitive Impairment

Background: Oxidative stress is one of the causative factors in the pathogenesis of neurodegenerative diseases including mild cognitive impairment (MCI) and dementia. We previously reported that molecular hydrogen (H2) acts as a therapeutic and preventive antioxidant. Objective: We assess the effects of drinking H2-water (water infused with H2) on oxidative stress model mice and subjects with MCI. Methods: Transgenic mice expressing a dominant-negative form of aldehyde dehydrogenase 2 were used as a dementia model. The mice with enhanced oxidative stress were allowed to drink H2-water. For a randomized double-blind placebo-controlled clinical study, 73 subjects with MCI drank ~300 mL of H2-water (H2-group) or placebo water (control group) per day, and the Alzheimer’s Disease Assessment Scale-cognitive subscale (ADAS-cog) scores were determined after 1 year. Results: In mice, drinking H2-water decreased oxidative stress markers and suppressed the decline of memory impairment and neurodegeneration. Moreover, the mean lifespan in the H2-water group was longer than that of the control group. In MCI subjects, although there was no significant difference between the H2- and control groups in ADAS-cog score after 1 year, carriers of the apolipoprotein E4 (APOE4) genotype in the H2-group were improved significantly on total ADAS-cog score and word recall task score (one of the sub-scores in the ADAS-cog score). Conclusion: H2-water may have a potential for suppressing dementia in an oxidative stress model and in the APOE4 carriers with MCI.

Molecular hydrogen suppresses free-radical-induced cell death by mitigating fatty acid peroxidation and mitochondrial dysfunction

Molecular hydrogen (H2) was believed to be an inert and nonfunctional molecule in mammalian cells; however, we overturned the concept by reporting the therapeutic effects of H2 against oxidative stress. Subsequently, extensive studies revealed multiple functions of H2 by exhibiting the efficacies of H2 in various animal models and clinical studies. Here, we investigated the effect of H2 on free-radical-induced cytotoxicity using tert-butyl hydroperoxide in a human acute monocytic leukemia cell line, THP-1. Cell membrane permeability was determined using lactate dehydrogenase release assay and Hoechst 33342 and propidium iodide staining. Fatty acid peroxidation and mitochondrial viability were measured using 2 kinds of fluorescent dyes, Liperfluo and C11-BODIPY, and using the alamarBlue assay based on the reduction of resazurin to resorufin by mainly mitochondrial succinate dehydrogenase, respectively. Mitochondrial membrane potential was evaluated using tetramethylrhodamine methyl ester. As a result, H2 protected the cultured cells against the cytotoxic effects induced by tert-butyl hydroperoxide; H2 suppressed cellular fatty acid peroxidation and cell membrane permeability, mitigated the decline in mitochondrial oxidoreductase activity and mitochondrial membrane potential, and protected cells against cell death evaluated using propidium iodide staining. These results suggested that H2 suppresses free-radical-induced cell death through protection against fatty acid peroxidation and mitochondrial dysfunction.