Molecular hydrogen regulates the expression of miR-9, miR-21 and miR-199 in LPS-activated retinal microglia cells

The Molecular Biological Mechanism of Hydrogen Therapy and Its Application in Spinal Cord Injury

Hydrogen, which is a novel biomedical molecule, is currently the subject of extensive research involving animal experiments and in vitro cell experiments, and it is gradually being applied in clinical settings. Hydrogen has been proven to possess anti-inflammatory, selective antioxidant, and antiapoptotic effects, thus exhibiting considerable protective effects in various diseases. In recent years, several studies have provided preliminary evidence for the protective effects of hydrogen on spinal cord injury (SCI). This paper provides a comprehensive review of the potential molecular biology mechanisms of hydrogen therapy and its application in treating SCI, with an aim to better explore the medical value of hydrogen and provide new avenues for the adjuvant treatment of SCI.

The effects of inhaling hydrogen gas on macrophage polarization, fibrosis, and lung function in mice with bleomycin-induced lung injury

Background

Acute respiratory distress syndrome, which is caused by acute lung injury, is a destructive respiratory disorder caused by a systemic inflammatory response. Persistent inflammation results in irreversible alveolar fibrosis. Because hydrogen gas possesses anti-inflammatory properties, we hypothesized that daily repeated inhalation of hydrogen gas could suppress persistent lung inflammation by inducing functional changes in macrophages, and consequently inhibit lung fibrosis during late-phase lung injury.

Methods

To test this hypothesis, lung injury was induced in mice by intratracheal administration of bleomycin (1.0 mg/kg). Mice were exposed to control gas (air) or hydrogen (3.2% in air) for 6 h every day for 7 or 21 days. Respiratory physiology, tissue pathology, markers of inflammation, and macrophage phenotypes were examined.

Results

Mice with bleomycin-induced lung injury that received daily hydrogen therapy for 21 days (BH group) exhibited higher static compliance (0.056 mL/cmH₂O, 95% CI 0.047–0.064) than mice with bleomycin-induced lung injury exposed only to air (BA group; 0.042 mL/cmH₂O, 95% CI 0.031–0.053, p = 0.02) and lower static elastance (BH 18.8 cmH₂O/mL, [95% CI 15.4–22.2] vs. BA 26.7 cmH₂O/mL [95% CI 19.6–33.8], p = 0.02). When the mRNA levels of pro-inflammatory cytokines were examined 7 days after bleomycin administration, interleukin (IL)-6, IL-4 and IL-13 were significantly lower in the BH group than in the BA group. There were significantly fewer M2-biased macrophages in the alveolar interstitium of the BH group than in the BA group (3.1% [95% CI 1.6–4.5%] vs. 1.1% [95% CI 0.3–1.8%], p = 0.008).

Conclusions

The results suggest that hydrogen inhalation inhibits the deterioration of respiratory physiological function and alveolar fibrosis in this model of lung injury.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01712-2.

Direct Targets and Subsequent Pathways for Molecular Hydrogen to Exert Multiple Functions: Focusing on Interventions in Radical Reactions

Molecular hydrogen (H₂) was long regarded as non-functional in mammalian cells. We overturned the concept by demonstrating that H₂ exhibits antioxidant effects and protects cells against oxidative stress. Subsequently, it has been revealed that H₂ has multiple functions in addition to antioxidant effects, including antiinflammatory, anti-allergic functions, and as cell death and autophagy regulation. Additionally, H₂ stimulates energy metabolism. As H₂ does not readily react with most biomolecules without a catalyst, it is essential to identify the primary targets with which H₂ reacts or interacts directly. As a first event, H₂ may react directly with strong oxidants, such as hydroxyl radicals (•OH) in vivo. This review addresses the key issues related to this in vivo reaction. •OH may have a physiological role because it triggers a free radical chain reaction and may be involved in the regulation of Ca2+- or mitochondrial ATP-dependent K+-channeling. In the subsequent pathway, H₂ suppressed a free radical chain reaction, leading to decreases in lipid peroxide and its end products. Derived from the peroxides, 4-hydroxy-2-nonenal functions as a mediator that up-regulates multiple functional PGC-1α. As the other direct target in vitro and in vivo, H₂ intervenes in the free radical chain reaction to modify oxidized phospholipids, which may act as an antagonist of Ca2+-channels. The resulting suppression of Ca2+-signaling inactivates multiple functional NFAT and CREB transcription factors, which may explain H₂ multi-functionality. This review also addresses the involvement of NFAT in the beneficial role of H₂ in COVID-19, Alzheimer's disease and advanced cancer. We discuss some unsolved issues of H₂ action on lipopolysaccharide signaling, MAPK and NF-κB pathways and the Nrf2 paradox. Finally, as a novel idea for the direct targeting of H2, this review introduces the possibility that H₂ causes structural changes in proteins via hydrate water changes.

Protective Effect of miR-340-5p against Brain Injury after Intracerebral Hemorrhage by Targeting PDCD4

OBJECTIVE

Intracerebral hemorrhage (ICH) is a common cerebrovascular disease. Increasing evidence has documented the crucial role of microRNAs in ICH. The present study aimed to investigate the role and underlying mechanism of miR-340-5p in ICH.

METHODS

The collagenase-induced ICH rat model was established. The neurological function of rats and the cerebral water content of rat brain tissue were measured to assess the brain injury. BV-2 cells were recruited and treated by LPS to mimic ICH-induced inflammatory response. qRT-PCR was used for the measurement of miR-340-5p. The protein levels of TNF-α, IL-6, and IL-1β were detected using ELISA. Luciferase reporter gene assay was performed to confirm the target gene.

RESULTS

Downregulation of miR-340-5p was detected in the serum of ICH patients and the brain tissues of ICH rats. Overexpression of miR-340-5p reversed the influence of ICH on the neurological function score and cerebral water content and inhibited the production of proinflammatory cytokines (TNF-α, IL-6, and IL-1β), which were induced by ICH in vivo. In in vitro study, levels of TNF-α, IL-6, and IL-1β were significantly enhanced in cells after LPS treatment, but these increases were eliminated by overexpression of miR-340-5p. PDCD4 was a direct target gene of miR-340-5p.

CONCLUSION

miR-340-5p protects against brain injury after ICH. miR-340-5p might exert an anti-inflammatory effect during the occurrence of ICH via targeting PDCD4.

Hydrogen promotes the activation of Cu, Zn superoxide dismutase in a rat corneal alkali-burn model

AIM

To investigate the effects of hydrogen (H₂) on Cu, Zn superoxide dismutase (SOD1) activation in a rat model of corneal alkali burn.

METHODS

In each rat, one cornea was subjected to alkali exposure. Physiological saline (saline group) or H₂-dissolved saline (H₂ group) was instilled continuously on the cornea for 5min before and after alkali exposure. Inflammatory cells, neovascularization, and cytoplasmic SOD1 levels were evaluated immunohistochemically in enucleated eyes from both groups. Three-dimensional ultrastructural tissue changes in the eyes were analyzed using low-vacuum scanning electron microscopy.

RESULTS

The numbers of both inflammatory and vascular endothelial cells were significantly reduced in the corneas of the H₂ group (P<0.01). Furthermore, H₂ treatment increased both cytoplasmic SOD1 levels (P<0.01) and activity in corneal epithelial cells (P<0.01). Notably, the SOD1 activity level in the H₂ group was approximately 2.5-fold greater than that in the saline group.

CONCLUSION

H₂ treatment suppresses inflammation and neovascularization in the injured cornea and indirectly suppresses oxidative insult to the cornea by upregulating the SOD1 enzyme protein level and activity.

Hydrogen gas therapy improves survival rate and neurological deficits in subarachnoid hemorrhage rats: a pilot study

The high morbidity, high mortality, and significant shortage of effective therapies for subarachnoid hemorrhage (SAH) have created an urgency to discover novel therapies. Human studies in Asia have established the safety of hydrogen gas in the treatment of hepatic, renal, pulmonary, and cardiac diseases. Mechanistically, hydrogen gas has been shown to affect oxidative stress, inflammation, and apoptosis. We hypothesized that hydrogen therapy would improve neurological function and increase survival rate in SAH. High dose hydrogen gas (66% at 3 L/min) was administered for 2 hours at 0.5, 8, and 18 hours after SAH. This treatment increased 72-hour survival rate and provided 24-hour neuroprotection after SAH in rats. To our knowledge, this is the first report demonstrating that high dose hydrogen gas therapy reduces mortality and improves outcome after SAH. Our results correlate well with the proposed mechanisms of hydrogen gas therapy within the literature. We outline four pathways and downstream targets of hydrogen gas potentially responsible for our results. A potentially complex network of pathways responsible for the efficacy of hydrogen gas therapy, along with a limited mechanistic understanding of these pathways, justifies further investigation to provide a basis for clinical trials and the advancement of hydrogen gas therapy in humans. This study was approved by the Institutional Animal Care and Use Committee of Loma Linda University, USA (Approval No. 8160016) in May 2016.

Molecular hydrogen: potential in mitigating oxidative-stress-induced radiation injury

Uncontrolled production of oxygen and nitrogen radicals results in oxidative and nitrosative stresses that impair cellular functions and have been regarded as causative common denominators of many pathological processes. In this review, we report on the beneficial effects of molecular hydrogen in scavenging radicals in an artificial system of•OH formation. As a proof of principle, we also demonstrate that in rat hearts in vivo, administration of molecular hydrogen led to a significant increase in superoxide dismutase as well as pAKT, a cell survival signaling molecule. Irradiation of the rats caused a significant increase in lipid peroxidation, which was mitigated by pre-treatment of the animals with molecular hydrogen. The nuclear factor erythroid 2-related factor 2 is regarded as an important regulator of oxyradical homeostasis, as well as it supports the functional integrity of cells, particularly under conditions of oxidative stress. We suggest that the beneficial effects of molecular hydrogen may be through the activation of nuclear factor erythroid 2-related factor 2 pathway that promotes innate antioxidants and reduction of apoptosis, as well as inflammation.

Regulation of microRNAs by molecular hydrogen contributes to the prevention of radiation-induced damage in the rat myocardium

microRNAs (miRNAs) constitute a large class of post-transcriptional regulators of gene expression. It has been estimated that miRNAs regulate up to 30% of the protein-coding genes in humans. They are implicated in many physiological and pathological processes, including those involved in radiation-induced heart damage. Biomedical studies indicate that molecular hydrogen has potential as a radioprotective agent due to its antioxidant, anti-inflammatory, and signal-modulating effects. However, the impact of molecular hydrogen on the expression of miRNAs in the heart after irradiation has not been investigated. This study aimed to explore the involvement of miRNA-1, -15b, and -21 in the protective action of molecular hydrogen on rat myocardium damaged by irradiation. The results showed that the levels of malondialdehyde (MDA) and tumor necrosis factor alpha (TNF-α) increased in the rat myocardium after irradiation. Treatment with molecular hydrogen-rich water (HRW) reduced these values to the level of non-irradiated controls. miRNA-1 is known to be involved in cardiac hypertrophy, and was significantly decreased in the rat myocardium after irradiation. Application of HRW attenuated this decrease in all evaluated time periods. miRNA-15b is considered to be anti-fibrotic, anti-hypertrophic, and anti-oxidative. Irradiation downregulated miRNA-15b, whereas administration of HRW restored these values. miRNA-21 is connected with cardiac fibrosis. We observed significant increase in miRNA-21 expression in the irradiated rat hearts. Molecular hydrogen lowered myocardial miRNA-21 levels after irradiation. This study revealed for the first time that the protective effects of molecular hydrogen on irradiation-induced heart damage may be mediated by regulating miRNA-1, -15b, and -21.

Emerging mechanisms and novel applications of hydrogen gas therapy

Clinical and pre-clinical studies have reported a broad range of applications for hydrogen gas therapy. Classically, conventional antioxidant therapy is limited because it neutralizes both the detrimental and protective effects of reactive oxygen species. As a weak reducing agent, hydrogen gas avoids this paradox by reacting with strong oxidants while leaving other beneficial oxidants reactive. This review gathers a promising list of hydrogen gas applications that merit further mechanistic investigation and additional therapeutic trials. Reports support the ability of hydrogen gas to downregulate the expression of pro-inflammatory cytokines and pro-apoptotic factors. Mechanistically, hydrogen gas has been shown to downregulate miR-9 and miR-21, while upregulating miR-199 to reduce inflammatory injury. In angiogenic pathways, hydrogen's inhibition of cyclic guanosine monophosphate-degrading phosphodiesterase led to higher levels of cyclic guanosine monophosphate, activation of protein kinase, and angiogenesis; next, as hydrogen gas increased the levels of intracellular calcium, stimulated vascular endothelial growth factor increased nitric oxide production. In conjunction, hydrogen gas opened adenosine triphosphate-sensitive potassium channel channels, which activate downstream mitogen-activated protein kinase pathways. Growing molecular mechanisms have discovered a plethora of downstream targets for hydrogen gas therapy that include autophagy (via the adenosine 5’-monophosphate-activated protein kinase/mammalian target of rapamycin pathway), histone modification, mitochondrial unfolded protein response, acute oxidative stress after exercise, and oxidative stress secondary to aging. In conclusion, evolving research has discovered novel molecular connections that will continue to widen applications for hydrogen therapy.

MicroRNA-30a-3p overexpression improves sepsis-induced cell apoptosis in vitro and in vivo via the PTEN/PI3K/AKT signaling pathway

The aim of the present study was to explain the mechanism of miR-30a-3p overexpression in sepsis-induced cell apoptosis in vitro and in vivo. For the in vitro cell experiments, H9c2 cells were divided into three groups, including the untreated normal control (NC), lipopolysaccharide (LPS)-treated and miRNA (treated with LPS and transfection with miRNA-30a-3p) groups. The cell proliferation and apoptosis were evaluated by MTT assay and flow cytometry, respectively. The relative protein expression levels were measured by western blot assay. In the in vivo experiment, a sepsis rat model was established by intraperitoneal injection of LPS. Sprague Dawley rats were divided into three groups, including the NC, LPS-injected and miRNA (in which model rats were injected with miR-30a-3p vector at the caudal vein) groups. The myocardial morphology in different groups was observed by hematoxylin and eosin staining. In addition, tissue apoptosis and protein expression levels were evaluated by TUNEL and western blot assay, respectively. The results of cell experiments indicated that the cell proliferation rate was significantly increased and the cell apoptosis rate was significantly downregulated in the miR-30a-3p group compared with the LPS group (both P<0.05). The relative protein expression of phosphatase and tensin homolog (PTEN) was markedly decreased in the miRNA group compared with the LPS group, while the levels of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT) were significantly increased in the miRNA group (all P<0.05). In the in vivo experiments, the myocardial morphology of the miRNA group was improved compared with that of the LPS group. Compared with the LPS group, cell apoptosis in the miRNA group was significantly downregulated (P<0.05), while the relative protein levels (PTEN, PI3K and AKT) in the tissues were also significantly altered (P<0.05). In conclusion, miR-30a-3p overexpression may improve the sepsis-induced cell apoptosis in vitro and in vivo via the PTEN/PI3K/AKT signaling pathway.

The transfer of hydrogen from inert gas to therapeutic gas

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

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

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

Molecular hydrogen increases resilience to stress in mice

The inability to successfully adapt to stress produces pathological changes that can lead to depression. Molecular hydrogen has anti-oxidative and anti-inflammatory activities and neuroprotective effects. However, the potential role of molecular hydrogen in stress-related disorders is still poorly understood. The present study aims to investigate the effects of hydrogen gas on resilience to stress in mice. The results showed that repeated inhalation of hydrogen-oxygen mixed gas [67%:33% (V/V)] significantly decreased both the acute and chronic stress-induced depressive- and anxiety-like behaviors of mice, assessed by tail suspension test (TST), forced swimming test (FST), novelty suppressed feeding (NSF) test, and open field test (OFT). ELISA analyses showed that inhalation of hydrogen-oxygen mixed gas blocked CMS-induced increase in the serum levels of corticosterone, adrenocorticotropic hormone, interleukin-6, and tumor necrosis factor-α in mice exposed to chronic mild stress. Finally, inhalation of hydrogen gas in adolescence significantly increased the resilience to acute stress in early adulthood, which illustrates the long-lasting effects of hydrogen on stress resilience in mice. This was likely mediated by inhibiting the hypothalamic-pituitary-adrenal axis and inflammatory responses to stress. These results warrant further exploration for developing molecular hydrogen as a novel strategy to prevent the occurrence of stress-related disorders.

Bone marrow-derived mesenchymal stem cells (BMSCs) repair acute necrotized pancreatitis by secreting microRNA-9 to target the NF-κB1/p50 gene in rats

Acute pancreatitis (AP) is a common acute abdominal disease, 10-20% of which can evolve into severe AP (SAP) causing significant morbidity and mortality. Bone marrow-derived mesenchymal stem cells (BMSCs) have the potential of repairing SAP, but the detailed mechanism remains unknown. We demonstrate here that microRNA-9 (miR-9) modified BMSCs (pri-miR-9-BMSCs) can significantly reduce the pancreatic edema, infiltration, hemorrhage, necrosis, the release of amylase and lipase. Meanwhile, decreased local/systemic inflammatory response (TNF-α↓, IL-1β↓, IL-6↓, HMGB1↓, MPO↓, CD68↓, IL-4↑, IL-10↑, and TGF-β↑) and enhanced regeneration of damaged pancreas (Reg4↑, PTF1↑, and PDX1↑) are also promoted. But these effects diminish or disappear after antagonizing miR-9 (TuD). Besides, we find that miR-9 is negatively correlated with AP and miR-9 agomir which can mimic the effects of pri-miR-9-BMSCs and protect injured pancreas. Furthermore, we investigate that BMSCs deliver miR-9 to the injured pancreas or peripheral blood mononuclear cell (PBMC), which can target the NF-κB1/p50 gene and inhibit the NF-κB signaling pathway (p-P65↓, NF-κB1/p50↓, IκBα↑, IκBβ↑). Taken together, these results show that miR-9 is a key paracrine factor of BMSCs attenuating SAP targeting the NF-κB1/p50 gene and suppressing the NF-κB signaling pathway.

The potential utilizations of hydrogen as a promising therapeutic strategy against ocular diseases

Hydrogen, one of the most well-known natural molecules, has been used in numerous medical applications owing to its ability to selectively neutralize cytotoxic reactive oxygen species and ameliorate hazardous inflammations. Hydrogen can exert protective effects on various reactive oxygen species-related diseases, including the transplantation-induced intestinal graft injury, chronic inflammation, ischemia–reperfusion injuries, and so on. Especially in the eye, hydrogen has been used to counteract multiple ocular pathologies in the ophthalmological models. Herein, the ophthalmological utilizations of hydrogen are systematically reviewed and the underlying mechanisms of hydrogen-induced beneficial effects are discussed. It is our hope that the protective effects of hydrogen, as evidenced by these pioneering studies, would enrich our pharmacological knowledge about this natural element and cast light into the discovery of a novel therapeutic strategy against ocular diseases.

Kissing-loop interaction between 5' and 3' ends of tick-borne Langat virus genome 'bridges the gap' between mosquito- and tick-borne flaviviruses in mechanisms of viral RNA cyclization: applications for virus attenuation and vaccine development

Insertion of microRNA target sequences into the flavivirus genome results in selective tissue-specific attenuation and host-range restriction of live attenuated vaccine viruses. However, previous strategies for miRNA-targeting did not incorporate a mechanism to prevent target elimination under miRNA-mediated selective pressure, restricting their use in vaccine development. To overcome this limitation, we developed a new approach for miRNA-targeting of tick-borne flavivirus (Langat virus, LGTV) in the duplicated capsid gene region (DCGR). Genetic stability of viruses with DCGR was ensured by the presence of multiple cis-acting elements within the N-terminal capsid coding region, including the stem-loop structure (5′SL6) at the 3′ end of the promoter. We found that the 5′SL6 functions as a structural scaffold for the conserved hexanucleotide motif at its tip and engages in a complementary interaction with the region present in the 3′ NCR to enhance viral RNA replication. The resulting kissing-loop interaction, common in tick-borne flaviviruses, supports a single pair of cyclization elements (CYC) and functions as a homolog of the second pair of CYC that is present in the majority of mosquito-borne flaviviruses. Placing miRNA targets into the DCGR results in superior attenuation of LGTV in the CNS and does not interfere with development of protective immunity in immunized mice.

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

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

Lipopolysaccharide-Induced Differential Expression of miRNAs in Male and Female Rhipicephalus haemaphysaloides Ticks

Lipopolysaccharide (LPS) stimulates the innate immune response in arthropods. In tick vectors, LPS activates expression of immune genes, including those for antibacterial peptides. miRNAs are 21-24 nt non-coding small RNAs that regulate target mRNAs at the post-transcriptional level. However, our understanding of tick innate immunity is limited to a few cellular immune reactions and some characterized immune molecules. Moreover, there is little information on the regulation of the immune system in ticks by miRNA. Therefore, this study aimed to analyze the differential expression of miRNAs in male and female ticks after LPS injection. LPS was injected into male and female Rhipicephalus haemaphysaloides ticks to stimulate immune response, with phosphate buffered saline (PBS)-injected ticks as negative controls. miRNAs from each group were sequenced and analyzed. In the PBS- and LPS-injected female ticks, 11.46 and 12.82 million reads of 18-30 nt were obtained respectively. There were 13.92 and 15.29 million reads of 18-30 nt obtained in the PBS- and LPS-injected male ticks, respectively. Expression of miRNAs in male ticks was greater than that in female ticks. There were 955 and 984 conserved miRNA families in the PBS- and LPS-injected female ticks, respectively, and correspondingly 1684 and 1552 conserved miRNA families in male ticks. Nine novel miRNAs were detected as common miRNAs in two or more tested samples. There were 37 known miRNAs up-regulated >10-fold and 33 down-regulated >10-fold in LPS-injected female ticks; and correspondingly 52 and 59 miRNAs in male ticks. Differential expression of miRNAs in PBS- and LPS-injected samples supports their involvement in the regulation of innate immunity. These data provide an important resource for more detailed functional analysis of miRNAs in this species.

Hydrogen improves neurological function through attenuation of blood-brain barrier disruption in spontaneously hypertensive stroke-prone rats

Background

Enhanced oxidative stress occurs in spontaneously hypertensive stroke-prone rats (SHRSP), and is important in blood–brain barrier (BBB) disruption. Hydrogen can exert potent protective cellular effects via reduction in oxidative stress in various diseases. The present study investigated whether long-term hydrogen treatment can improve neurological function outcome in the SHRSP model, and the effects of hydrogen on BBB function, especially the oxidative stress and the activity of matrix metalloproteinases (MMPs) in this model. Fifty-six animals were randomly assigned to 2 groups and treated as follows: SHRSP treated with hydrogen-rich water (HRW) (HRW group, n = 28); and SHRSP treated with regular water (control group, n = 28). The effect of HRW on overall survival and neurological function, and the effects of HRW on reactive oxygen species, BBB function, and MMP activities were examined.

Results

HRW treatment improved neurological function and tended to improve overall survival but without significant difference. The numbers of bleeds and infarcts were lower in the cortex and hippocampus in the HRW group. The HRW group exhibited a significantly lower number of 8-hydroxy-2'-deoxyguanosine-positive cells and vessels of extravasated albumin in the hippocampus compared with the control group. MMP-9 activity was reduced in the hippocampus in the HRW group compared with the control group.

Conclusions

The present study suggests that ingestion of HRW can improve neurological function outcome in the SHRSP model. This beneficial effect may be due to attenuation of BBB disruption via reduction in reactive oxygen species and suppression of MMP-9 activity in the hippocampus.

MicroRNA-9 controls dendritic development by targeting REST

MicroRNAs (miRNAs) are conserved noncoding RNAs that function as posttranscriptional regulators of gene expression. miR-9 is one of the most abundant miRNAs in the brain. Although the function of miR-9 has been well characterized in neural progenitors, its role in dendritic and synaptic development remains largely unknown. In order to target miR-9 in vivo, we developed a transgenic miRNA sponge mouse line allowing conditional inactivation of the miR-9 family in a spatio-temporal-controlled manner. Using this novel approach, we found that miR-9 controls dendritic growth and synaptic transmission in vivo. Furthermore, we demonstrate that miR-9-mediated downregulation of the transcriptional repressor REST is essential for proper dendritic growth.

DOI:http://dx.doi.org/10.7554/eLife.02755.001

Messages are sent back and forth in our brains by cells called neurons that connect to each other in complex networks. Neurons develop from stem cells in a complicated process that involves a number of different stages. In one of the final stages, tree-like structures called dendrites emerge from the neurons and connect with neighboring neurons via special junctions called synapses.

A group of small RNA molecules called microRNAs have roles in controlling the development of neurons. One microRNA, called miR-9, is abundant in the brain and is known to be involved in the early stages of neuron development. However, its role in the formation of dendrites and synapses remains unclear.

Giusti et al. studied this microRNA in mice. A length of DNA, coding for an RNA molecule that binds to miR-9 molecules and stops them performing their normal function, was inserted into the mice. These experiments showed that miR-9 is involved in controlling dendrite growth and synaptic function.

To enable a neuron to produce dendrites, miR-9 binds to and interferes with the RNA molecules that are needed to make a protein called REST. This protein is a transcription factor that switches off the expression of other genes so, in effect, miR-9 allows a set of genes that are needed for dendrite growth to be switched on.

The methodology developed by Giusti et al. could be used to study the functions of other microRNAs.

DOI:http://dx.doi.org/10.7554/eLife.02755.002

MiR-9 regulates the post-transcriptional level of VEGF165a by targeting SRPK-1 in ARPE-19 cells

PURPOSE

To investigate the effect of the overexpression of miRNA-9 to the ratio of pro- and anti-angiogenic isoforms of vascular endothelial growth factor (VEGF) in human retinal pigment cells (ARPE-19).

METHODS

Oxidative stress was induced to ARPE-19 cells by 4-hydroxynonenal (4-HNE), tert-butyl hydroperoxide (t-BH), and hypoxia chamber with 1% O₂. Expression patterns of miRNAs were validated by qPCR. Relative mRNA levels of VEGF and PEDF were measured by semi-quantitative PCR. After the transfection of miR-9 mimic and inhibitor, transcriptional levels of VEGF165a, VEGF 165b, and SRPK-1 were measured by qPCR.

RESULTS

We demonstrated that miR-9 expression is decreased in ARPE-19 human retinal pigment cells under hypoxic stress induced by 4-HNE, a lipid peroxidation end-product. We observed that miR-9 mimic transfection of ARPE-19 inhibited one of its targets, serine-arginine protein kinase-1 (SRPK-1), modulating the transcriptional level of VEGF165b. Transfection of miR-9 reduced the alternative splicing of VEGF165a mRNA in ARPE-19 cells under hypoxic conditions, suggesting that miR-mediated regulation of alternative splicing could be a potential therapeutic target in neovascular pathologies.

CONCLUSIONS

Hypoxic stress decreased the miR-9 level in ARPE-19 cells, which increased the transcriptional level of SRPK-1, resulting in alternative splicing shift to pro-angiogenic isoforms of VEGF165 in human retinal pigment epithelial cells.

Neuroprotective effect of hydrogen-rich saline against neurologic damage and apoptosis in early brain injury following subarachnoid hemorrhage: possible role of the Akt/GSK3β signaling pathway

Backgrounds

Early brain injury (EBI) plays a key role in the pathogenesis of subarachnoid hemorrhage (SAH). Neuronal apoptosis is involved in the pathological process of EBI. Hydrogen can inhibit neuronal apoptosis and attenuate EBI following SAH. However, the molecular mechanism underlying hydrogen-mediated anti-apoptotic effects in SAH has not been elucidated. In the present study, we aimed to evaluate whether hydrogen alleviates EBI after SAH, specifically neuronal apoptosis, partially via the Akt/GSK3β signaling pathway.

Methods

Sprague-Dawley rats (n = 85) were randomly divided into the following groups: sham group (n = 17), SAH group (n = 17), SAH + saline group (n = 17), SAH + hydrogen-rich saline (HS) group (n = 17) and SAH + HS + Ly294002 (n = 17) group. HS or an equal volume of physiological saline was administered immediately after surgery and repeated 8 hours later. The PI3K inhibitor, Ly294002, was applied to manipulate the proposed pathway. Neurological score and SAH grade were assessed at 24 hours after SAH. Western blot was used for the quantification of Akt, pAkt, GSK3β, pGSK3β, Bcl-2, Bax and cleaved caspase-3 proteins. Neuronal apoptosis was identified by double staining of terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining and NeuN, and quantified by apoptosis index. Immunohistochemistry and immunofluorescent double-labeling staining was performed to clarify the relationships between neuronal apoptosis and pAkt or pGSK3β.

Results

HS significantly reduced neuronal apoptosis and improved neurological function at 24 hours after SAH. The levels of pAkt and pGSK3β, mainly expressed in neurons, were markedly up-regulated. Additionally, Bcl-2 was significantly increased while Bax and cleaved caspase-3 was decreased by HS treatment. Double staining of pAkt and TUNEL showed few colocalization of pAkt-positive cells and TUNEL-positive cells. The inhibitor of PI3K, Ly294002, suppressed the beneficial effects of HS.

Conclusions

HS could attenuate neuronal apoptosis in EBI and improve the neurofunctional outcome after SAH, partially via the Akt/GSK3β pathway.