Hydrogen inhalation ameliorates ventilator-induced lung injury

Combination of Hydrogen Inhalation and Hypothermic Temperature Control After Out-of-Hospital Cardiac Arrest: A Post hoc Analysis of the Efficacy of Inhaled Hydrogen on Neurologic Outcome Following Brain Ischemia During PostCardiac Arrest Care II Trial

OBJECTIVE

The Efficacy of Inhaled Hydrogen on Neurologic Outcome Following Brain Ischemia During Post-Cardiac Arrest Care (HYBRID) II trial (jRCTs031180352) suggested that hydrogen inhalation may reduce post-cardiac arrest brain injury (PCABI). However, the combination of hypothermic target temperature management (TTM) and hydrogen inhalation on outcomes is unclear. The aim of this study was to investigate the combined effect of hydrogen inhalation and hypothermic TTM on outcomes after out-of-hospital cardiac arrest (OHCA).

DESIGN

Post hoc analysis of a multicenter, randomized, controlled trial.

SETTING

Fifteen Japanese ICUs.

PATIENTS

Cardiogenic OHCA enrolled in the HYBRID II trial.

INTERVENTIONS

Hydrogen mixed oxygen (hydrogen group) versus oxygen alone (control group).

MEASUREMENTS AND MAIN RESULTS

TTM was performed at a target temperature of 32-34°C (TTM32-TTM34) or 35-36°C (TTM35-TTM36) per the institutional protocol. The association between hydrogen + TTM32-TTM34 and 90-day good neurologic outcomes was analyzed using generalized estimating equations. The 90-day survival was compared between the hydrogen and control groups under TTM32-TTM34 and TTM35-TTM36, respectively. The analysis included 72 patients (hydrogen [n = 39] and control [n = 33] groups) with outcome data. TTM32-TTM34 was implemented in 25 (64%) and 24 (73%) patients in the hydrogen and control groups, respectively (p = 0.46). Under TTM32-TTM34, 17 (68%) and 9 (38%) patients achieved good neurologic outcomes in the hydrogen and control groups, respectively (relative risk: 1.81 [95% CI, 1.05-3.66], p < 0.05). Hydrogen + TTM32-TTM34 was independently associated with good neurologic outcomes (adjusted odds ratio 16.10 [95% CI, 1.88-138.17], p = 0.01). However, hydrogen + TTM32-TTM34 did not improve survival compared with TTM32-TTM34 alone (adjusted hazard ratio: 0.22 [95% CI, 0.05-1.06], p = 0.06).

CONCLUSIONS

Hydrogen + TTM32-TTM34 was associated with improved neurologic outcomes after cardiogenic OHCA compared with TTM32-TTM34 monotherapy. Hydrogen inhalation is a promising treatment option for reducing PCABI when combined with TTM32-TTM34.

Hydrogen in Transplantation: Potential Applications and Therapeutic Implications

Hydrogen gas, renowned for its antioxidant properties, has emerged as a novel therapeutic agent with applications across various medical domains, positioning it as a potential adjunct therapy in transplantation. Beyond its antioxidative properties, hydrogen also exerts anti-inflammatory effects by modulating pro-inflammatory cytokines and signaling pathways. Furthermore, hydrogen's capacity to activate cytoprotective pathways bolsters cellular resilience against stressors. In recent decades, significant advancements have been made in the critical medical procedure of transplantation. However, persistent challenges such as ischemia-reperfusion injury (IRI) and graft rejection continue to hinder transplant success rates. This comprehensive review explores the potential applications and therapeutic implications of hydrogen in transplantation, shedding light on its role in mitigating IRI, improving graft survival, and modulating immune responses. Through a meticulous analysis encompassing both preclinical and clinical studies, we aim to provide valuable insights into the promising utility of hydrogen as a complementary therapy in transplantation.

Hydrogen attenuates endothelial glycocalyx damage associated with partial cardiopulmonary bypass in rats

Cardiopulmonary bypass (CPB) causes systemic inflammation and endothelial glycocalyx damage. Hydrogen has anti-oxidant and anti-inflammatory properties; therefore, we hypothesized that hydrogen would alleviate endothelial glycocalyx damage caused by CPB. Twenty-eight male Sprague-Dawley rats were randomly divided into four groups (n = 7 per group), as follows: sham, control, 2% hydrogen, and 4% hydrogen. The rats were subjected to 90 minutes of partial CPB followed by 120 minutes of observation. In the hydrogen groups, hydrogen was administered via the ventilator and artificial lung during CPB, and via the ventilator for 60 minutes after CPB. After observation, blood collection, lung extraction, and perfusion fixation were performed, and the heart, lung, and brain endothelial glycocalyx thickness was measured by electron microscopy. The serum syndecan-1 concentration, a glycocalyx component, in the 4% hydrogen group (5.7 ± 4.4 pg/mL) was lower than in the control (19.5 ± 6.6 pg/mL) and 2% hydrogen (19.8 ± 5.0 pg/mL) groups (P < 0.001 for each), but it was not significantly different from the sham group (6.2 ± 4.0 pg/mL, P = 0.999). The endothelial glycocalyces of the heart and lung in the 4% hydrogen group were thicker than in the control group. The 4% hydrogen group had lower inflammatory cytokine concentrations (interleukin-1β and tumor necrosis factor-α) in serum and lung tissue, as well as a lower serum malondialdehyde concentration, than the control group. The 2% hydrogen group showed no significant difference in the serum syndecan-1 concentration compared with the control group. However, non-significant decreases in serum and lung tissue inflammatory cytokine concentrations, as well as in serum malondialdehyde concentration, were observed. Administration of 4% hydrogen via artificial and autologous lungs attenuated endothelial glycocalyx damage caused by partial CPB in rats, which might be mediated by the anti-inflammatory and anti-oxidant properties of hydrogen.

Molecular hydrogen: prospective treatment strategy of kidney damage after cardiac surgery

Cardiac surgery-associated acute kidney injury is a common post-operative complication, mostly due to increasing oxidative stress. Recently, molecular hydrogen (H2 gas) has also been applied to cardiac surgery due to its ability to reduce oxidative stress. We evaluated the potential effect of H2 application on the kidney in an in vivo model of simulated heart transplantation. Pigs underwent cardiac surgery within 3 h while connected to extracorporeal circulation (ECC) and subsequent 60 min of spontaneous reperfusion of the heart. We used two experimental groups: T-pigs after transplantation and TH-pigs after transplantation treated with 4% H2 mixed with air during inhalation of anesthesia and throughout oxygenation of blood in ECC. The levels of creatinine, urea and phosphorus were measured in plasma. Renal tissue samples were analyzed by Western blot method for protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap-1), and superoxide dismutase (SOD1). After cardiac surgery, selected plasma biomarkers were elevated. However, H2 therapy was followed by the normalization of all these parameters. Our results suggest activation of Nrf2/Keap1 pathway as well as increased SOD1 protein expression in the group treated with H2. The administration of H2 had a protective effect on the kidneys of pigs after cardiac surgery, especially in terms of normalization of plasma biomarkers to control levels.

Hydrogen inhalation attenuates lung contusion after blunt chest trauma in mice

BACKGROUND

Lung contusion caused by blunt chest trauma evokes a severe inflammatory reaction in the pulmonary parenchyma that may be associated with acute respiratory distress syndrome. Although hydrogen gas has antioxidant and anti-inflammatory effects and is protective against multiple types of lung injury at safe concentrations, the effects of inhaled hydrogen gas on blunt lung injury have not been previously investigated. Therefore, using a mouse model, we tested the hypothesis that hydrogen inhalation after chest trauma would reduce pulmonary inflammation and acute lung injury associated with lung contusion.

METHODS

Inbred male C57BL/6 mice were randomly divided into 3 groups: sham with air inhalation, lung contusion with air inhalation, and lung contusion with 1.3% hydrogen inhalation. Experimental lung contusion was induced using a highly reproducible and standardized apparatus. Immediately after induction of lung contusion, mice were placed in a chamber exposed to 1.3% hydrogen gas in the air. Histopathological analysis and real-time polymerase chain reaction in lung tissue and blood gas analysis were performed 6 hours after contusion.

RESULTS

Histopathological examination of the lung tissue after contusion revealed perivascular/intra-alveolar hemorrhage, perivascular/interstitial leukocyte infiltration, and interstitial/intra-alveolar edema. These histological changes and the extent of lung contusion, as determined by computed tomography, were significantly mitigated by hydrogen inhalation. Hydrogen inhalation also significantly reduced inflammatory cytokine and chemokine mRNA levels and improved oxygenation.

CONCLUSION

Hydrogen inhalation therapy significantly mitigated inflammatory responses associated with lung contusion in mice. Hydrogen inhalation therapy may be a supplemental therapeutic strategy for treating lung contusion.

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.

Potent anti-inflammatory responses: Role of hydrogen in IL-1α dominated early phase systemic inflammation

Introduction: It has been proven that hydrogen has obvious anti-inflammatory effects in animal experiments and clinical practice. However, the early dynamic process of the inflammatory response caused by lipopolysaccharide (LPS) and the anti-inflammatory effect of hydrogen has not been definitively reported.

Methods: Inflammation in male C57/BL6J mice or RAW264.7 cells was induced with LPS, for which hydrogen was immediately administered until samples were taken. Pathological changes in lung tissue were assessed using hematoxylin and eosin (HE) staining. Levels of inflammatory factors in serum were determined using liquid protein chip. The mRNA levels of chemotactic factors in lung tissues, leukocytes, and peritoneal macrophages were measured by qRT-PCR. The expression levels of IL-1α and HIF-1α were measured by immunocytochemistry.

Results: Hydrogen alleviated LPS-induced inflammatory infiltration in the lung tissues of mice. Among the 23 inflammatory factors screened, LPS-induced upregulation of IL-1α etc. was significantly inhibited by hydrogen within 1 hour. The mRNA expression of MCP-1, MIP-1α, G-CSF, and RANTES was inhibited obviously by hydrogen at 0.5 and 1 h in mouse peritoneal macrophages. In addition, hydrogen significantly blocked LPS or H2O2-induced upregulation of HIF-1α, and IL-1α in 0.5 h in RAW264.7 cells.

Discussion: The results suggested that hydrogen is potentially inhibitive against inflammation by inhibiting HIF-1α and IL-1α release at early occurrence. The target of the inhibitive LPS-induced-inflammatory action of hydrogen is chemokines in macrophages in the peritoneal cavity. This study provides direct experimental evidence for quickly controlling inflammation with the translational application of a hydrogen-assisted protocol.

Annexin A1 peptide Ac2-26 mitigates ventilator-induced lung injury in acute respiratory distress syndrome rats and partly depended on the endothelial nitric oxide synthase pathway

PURPOSE

Although mechanical ventilation is an essential support for acute respiratory distress syndrome (ARDS), ventilation also leads to ventilator-induced lung injury (VILI). This study aimed to estimate the effect and mechanism of Annexin A1 peptide (Ac2-26) on VILI in ARDS rats.

METHODS

Thirty-two rats were randomized into the sham (S), mechanical ventilation (V), mechanical ventilation/Ac2-26 (VA), and mechanical ventilation/Ac2-26/L-NIO (VAL) groups. The S group only received anesthesia, and the other three groups received endotoxin and then ventilation for 4 h. Rats in the V, VA and VAL groups received saline, Ac2-26, and A c2-26/N5-(1-iminoethyl)-l-ornithine (L-NIO), respectively.

RESULTS

All indexes deteriorated in the V, VA and VAL groups compared with the S group. Compared with V group, the PaO2/FiO2 ratio was increased, but the wet-to-dry weight ratio and protein levels in bronchoalveolar lavage fluid were decreased in the VA group. The inflammatory cells and proinflammatory factors were reduced by Ac2-26. The oxidative stress response, lung injury and apoptosis were also decreased by Ac2-26 compared to V group. All improvements of Ac2-26 were partly reversed by L-NIO.

CONCLUSIONS

Ac2-26 mitigates VILI in ARDS rats and partly depended on the endothelial nitric oxide synthase pathway.

Hydrogen gas alleviates lipopolysaccharide-induced acute lung injury and inflammatory response in mice

Background

Chronic inflammation and oxidant/antioxidant imbalance are two main pathological features associated with lipopolysaccharide (LPS)-induced acute lung injury (ALI). The following study investigated the protective role of hydrogen (H₂), a gaseous molecule without known toxicity, in LPS-induced lung injury in mice and explored its potential molecular mechanisms.

Methods

Mice were randomly divided into three groups: H₂ control group, LPS group, and LPS + H₂ group. The mice were euthanized at the indicated time points, and the specimens were collected. The 72 h survival rates, cytokines contents, pathological changes, expression of Toll-like receptor 4 (TLR4), and oxidative stress indicators were analyzed. Moreover, under different culture conditions, RAW 264.7 mouse macrophages were used to investigate the potential molecular mechanisms of H₂ in vitro. Cells were divided into the following groups: PBS group, LPS group, and LPS + H₂ group. The cell viability, intracellular ROS, cytokines, and expression of TLR4 and nuclear factor kappa-B (NF-κB) were observed.

Results

Hydrogen inhalation increased the survival rate to 80%, reduced LPS-induced lung damage, and decreased inflammatory cytokine release in LPS mice. Besides, H₂ showed remarked anti-oxidative activity to reduce the MDA and NO contents in the lung. In vitro data further indicated that H₂ down-regulates the levels of ROS, NO, TNF-α, IL-6, and IL-1β in LPS-stimulated macrophages and inhibits the expression of TLR4 and the activation of nuclear factor kappa-B (NF-κB).

Conclusion

Hydrogen gas alleviates lipopolysaccharide-induced acute lung injury and inflammatory response most probably through the TLR4-NF-κB pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12950-022-00314-x.

Hydrogen-rich and hyperoxygenate saline inhibits lipopolysaccharide-induced lung injury through mediating NF-κB/NLRP3 signaling pathway in C57BL/6 mice

BACKGROUND

Background: Acute lung injury (ALI) is one kind of frequently occurred emergency in Intensive Care Unite with a high mortality. The underlying causes are uncontrolled inflammatory reactions and intractable hypoxemia, which are difficult to control and improve. In the past 10 years, gas medical studies have found that both hydrogen molecules and oxygen molecules have protective effects on acute lung injury by improving inflammatory reactions and hypoxia, respectively. Oxygen is an oxidant and hydrogen is an antioxidant. In this study, we investigated the combined effect of above two-gas molecular on lipopolysaccharide (LPS) -induced acute lung injury.

METHODS

To clarify whether the combination of hydrogen and oxygen could increase or cancel out the protective effect, an ALI mice model induced by intraperitoneal injection of LPS was established, and the degree of lung tissue and mitochondria damage was evaluated based on the pathological sections, inflammatory factors, wet-dry ratio, bronchoalveolar lavage fluid (BALF). Immunohistochemistry, electron microscopy, western blotting and other detection methods also used to evaluate the therapeutic effect on acute lung injury model.

RESULTS

We observed that the combined protective effect of hydrogen and oxygen was superior to their respective protective effects, and the specific molecular mechanisms of the two therapies might be different.

CONCLUSION

Hydrogen plays a more important role in the inflammatory and anti-apoptosis mechanisms, while oxygen improves hypoxia of the body, and thus, its molecular mechanism may be closely associated to the hypoxia pathways.

Hydrogen Repairs LPS-Induced Endothelial Progenitor Cells Injury via PI3K/AKT/eNOS Pathway

Endotoxins and other harmful substances may cause an increase in permeability in endothelial cells (ECs) monolayers, as well as ECs shrinkage and death to induce lung damage. Lipopolysaccharide (LPS) can impair endothelial progenitor cells (EPCs) functions, including proliferation, migration, and tube formation. EPCs can migrate to the damaged area, differentiate into ECs, and participate in vascular repair, which improves pulmonary capillary endothelial dysfunction and maintains the integrity of the endothelial barrier. Hydrogen (H2) contributes to the repairment of lung injury and the damage of ECs. We therefore speculate that H2 protects the EPCs against LPS-induced damage, and it's mechanism will be explored. The bone marrow-derived EPCs from ICR Mice were treated with LPS to establish a damaged model. Then EPCs were incubated with H2, and treated with PI3K inhibitor LY294002 and endothelial nitric oxide synthase (eNOS) inhibitor L-NAME. MTT assay, transwell assay and tube formation assay were used to detect the proliferation, migration and angiogenesis of EPCs. The expression levels of target proteins were detected by Western blot. Results found that H2 repaired EPCs proliferation, migration and tube formation functions damaged by LPS. LY294002 and L-NAME significantly inhibited the repaired effect of H2 on LPS-induced dysfunctions of EPCs. H2 also restored levels of phosphor-AKT (p-AKT), eNOS and phosphor-eNOS (p-eNOS) suppressed by LPS. LY294002 significantly inhibited the increase of p-AKT and eNOS and p-eNOS expression exposed by H2. L-NAME significantly inhibited the increase of eNOS and p-eNOS expression induced by H2. H2 repairs the dysfunctions of EPCs induced by LPS, which is mediated by PI3K/AKT/eNOS signaling pathway.

Magnesium Hydride Ameliorates Endotoxin-Induced Acute Respiratory Distress Syndrome by Inhibiting Inflammation, Oxidative Stress, and Cell Apoptosis

Acute respiratory distress syndrome (ARDS) causes uncontrolled pulmonary inflammation, resulting in high morbidity and mortality in severe cases. Given the antioxidative effect of molecular hydrogen, some recent studies suggest the potential use of molecular hydrogen as a biomedicine for the treatment of ARDS. In this study, we aimed to explore the protective effects of magnesium hydride (MgH2) on two types of ARDS models and its underlying mechanism in a lipopolysaccharide (LPS)-induced ARDS model of the A549 cell line. The results showed that LPS successfully induced oxidative stress, inflammatory reaction, apoptosis, and barrier breakdown in alveolar epithelial cells (AEC). MgH2 can exert an anti-inflammatory effect by down-regulating the expressions of inflammatory cytokines (IL-1β, IL-6, and TNF-α). In addition, MgH2 decreased oxidative stress by eliminating intracellular ROS, inhibited apoptosis by regulating the expressions of cytochrome c, Bax, and Bcl-2, and suppressed barrier breakdown by up-regulating the expression of ZO-1 and occludin. Mechanistically, the expressions of p-AKT, p-mTOR, p-P65, NLRP3, and cleaved-caspase-1 were decreased after MgH2 treatment, indicating that AKT/mTOR and NF-κB/NLRP3/IL-1β pathways participated in the protective effects of MgH2. Furthermore, the in vivo study also demonstrated that MgH2-treated mice had a better survival rate and weaker pathological damage. All these findings demonstrated that MgH2 could exert an ARDS-protective effect by regulating the AKT/mTOR and NF-κB/NLRP3/IL-1β pathways to suppress LPS-induced inflammatory reaction, oxidative stress injury, apoptosis, and barrier breakdown, which may provide a potential strategy for the prevention and treatment of ARDS.

Molecular hydrogen is a potential protective agent in the management of acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome, which is a more severe form of ALI, are life-threatening clinical syndromes observed in critically ill patients. Treatment methods to alleviate the pathogenesis of ALI have improved to a great extent at present. Although the efficacy of these therapies is limited, their relevance has increased remarkably with the ongoing pandemic caused by the novel coronavirus disease 2019 (COVID-19), which causes severe respiratory distress syndrome. Several studies have demonstrated the preventive and therapeutic effects of molecular hydrogen in the various diseases. The biological effects of molecular hydrogen mainly involve anti-inflammation, antioxidation, and autophagy and cell death modulation. This review focuses on the potential therapeutic effects of molecular hydrogen on ALI and its underlying mechanisms and aims to provide a theoretical basis for the clinical treatment of ALI and COVID-19.

Molecular hydrogen is a promising therapeutic agent for pulmonary disease

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

Hydrogen, 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.

Nano-bubble hydrogen water: an effective therapeutic agent against inflammation related disease caused by viral infection in zebrafish model

Since the anti-inflammatory effect of hydrogen has been widely known, it was supposed that hydrogen could suppress tissue damage by inhibiting virus-related inflammatory reactions. However, hydrogen is slightly soluble in water, which leads to poor effect of oral hydrogen-rich water therapy. In this study, the nano-bubble hydrogen water (nano-HW) (about 0.7 ​ppm) was prepared and its therapeutic effect against viral infection was investigated by utilizing spring viraemia of carp virus (SVCV)-infected zebrafish as model. Three-month-old zebrafish were divided into nano-HW treatment–treated group and aquaculture water treated group (control group). The results revealed that the cumulative mortality rate of SVCV-infected zebrafish was reduced by 40% after treatment with nano-bubble hydrogen water, and qRT-PCR results showed that SVCV replication was significantly inhibited. Histopathological examination staining showed that SVCV infection caused tissue damage was greatly alleviated after treatment with nano-bubble hydrogen water. Futhermore, SVCV infection caused reactive oxygen species (ROS) accumulation was significantly reduced upon nano-HW treatment. The level of proinflammatory cytokines IL-1β, IL-8, and TNF-α was remarkably reduced in the nano-HW-treated group in vivo and in vitro. Taken together, our data demonstrated for the first time that nano-HW could inhibit the inflammatory response caused by viral infection in zebrafish, which suggests that nano-HW can be applied to antiviral research，and provides a novel therapeutic strategy for virus-caused inflammation related disease.

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Nano-HW treatment reduces the mortality of SVCV-infected zebrafish.

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Nano-HW alleviates the inflammatory response caused by SVCV infection.

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Nano-HW inhibits SVCV replication.

Ac2-26 mitigated acute respiratory distress syndrome rats via formyl peptide receptor pathway

BACKGROUND

Acute respiratory distress syndrome (ARDS) is characterized by severe local and systemic inflammation. Ac2-26, an Annexin A1 Peptide, can reduce the lung injury induced by reperfusion via the inhibition of inflammation. The present study aims to evaluate the effect and mechanism of Ac2-26 in ARDS.

METHODS

Thirty-two rats were anaesthetized and randomized into four groups: sham (S), ARDS (A), ARDS/Ac2-26 (AA), and ARDS/Ac2-26/BOC-2 (AAB) groups. Rats in the S group received saline for intratracheal instillation, while rats in the other three groups received endotoxin for intratracheal instillation, in order to prepare the ARDS and inject the saline, Ac2-26, and Ac2-26 combined with BOC-2. After 24 h, the PaO2/FiO2 ratio was calculated. The lung tissue wet-to-dry weight ratio and the protein level in bronchoalveolar lavage fluid (BALF) were tested. Then, the cytokines in BALF and serum, and the inflammatory cells in BALF were investigated. Afterwards, the oxidative stress response and histological injury was evaluated. Subsequently, the epithelium was cultured and analyzed to estimate the effect of Ac2-26 on apoptosis.

RESULTS

Compared to the S group, all indexes worsened in the A, AA, and AAB groups. Furthermore, compared to the S group, Ac2-26 significantly improved the lung injury and alveolar-capillary permeability, and inhibited the oxidative stress response. In addition, Ac2-26 reduced the local and systemic inflammation through the regulation of pro- and anti-inflammatory cytokines, and the decrease in inflammatory cells in BALF. Moreover, Ac2-26 inhibited the epithelium apoptosis induced by LPS through the modulation of apoptosis-regulated proteins. The protective effect of Ac2-26 on ARDS was partially reversed by the FPR inhibitor, BOC-2.

CONCLUSION

Ac2-26 reduced the lung injury induced by LPS, promoted alveolar-capillary permeability, ameliorated the local and systemic inflammation, and inhibited the oxidative stress response and apoptosis. The protection of Ac2-26 on ARDS was mainly dependent on the FPR pathway.

Attenuation of ventilator-induced lung injury through suppressing the pro-inflammatory signaling pathways: A review on preclinical studies

Mechanical ventilation (MV) is a relatively common medical intervention in ICU patients. The main side effect of MV is the so-called "ventilator-induced lung injury" (VILI). The pathogenesis of VILI is not completely understood; however, it has been reported that MV might be associated with up-regulation of various inflammatory mediators within the lung tissue and that these mediators might act as pathogenic factors in lung tissue injury. One potential mechanism for the generation of inflammatory mediators is through the release of endogenous molecules known as damage associated molecular patterns (DAMPs). These molecules are released from injured tissues and can bind to pattern recognition receptors (PRRs). PRR activation generally leads to the production and release of inflammation-related molecules including innate immune cytokines and chemokines. It has been suggested that blocking DAMP/PRR signaling pathways might diminish the progression of VILI. Herein, we review the latest findings with regard to the effects of DAMP/PRRs and their blockade, as well as the potential therapeutic targets and future research directions in VILI. Results of studies performed on human samples, animal models of disease, as well as relevant in vitro systems will be discussed.

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.

Luminal preloading with hydrogen-rich saline ameliorates ischemia-reperfusion injury following intestinal transplantation in rats

Prolonged intestinal cold storage causes considerable mucosal breakdown, which could bolster bacterial translocation and cause life-threatening infection for the transplant recipient. The intestine has an intraluminal compartment, which could be a target for intervention, but has not yet been fully investigated. Hydrogen gas exerts organ protection and has used been recently in several clinical and basic research studies on topics including intestinal transplantation. In this study, we aimed to investigate the cytoprotective efficacy of intraluminally administered hydrogen-rich saline on cold IR injury in intestinal transplantation. Isogeneic intestinal transplantation with 6 hours of cold ischemia was performed on Lewis rats. Hydrogen-rich saline (H₂ concentration at 5 ppm) or normal saline was intraluminally introduced immediately before preservation. Graft intestine was excised 3 hours after reperfusion and analyzed. Histopathological analysis of control grafts revealed blunting of the villi and erosion. These mucosal changes were notably attenuated by intraluminal hydrogen. Intestinal mucosa damage caused by IR injury led to considerable deterioration of gut barrier function 3 h post-reperfusion. However, this decline in permeability was critically prevented by hydrogen treatment. IR-induced upregulation of proinflammatory cytokine mRNAs such as IL-6 was mitigated by hydrogen treatment. Western blot revealed that hydrogen treatment regulated loss of the transmembrane protein ZO-1. Hydrogen-rich saline intraluminally administered in the graft intestine modulated IR injury to transplanted intestine in rats. Successful abrogation of intestinal IR injury with a novel strategy using intraluminal hydrogen may be easily clinically applicable and will compellingly improve patient care after transplantation.

Hydrogen: A Potential New Adjuvant Therapy for COVID-19 Patients

Hydrogen has been shown to have antioxidant, anti-inflammatory, hormone-regulating, and apoptosis-resistance properties, among others. Based on a review of the research, the use of hydrogen might reduce the destructive cytokine storm and lung injury caused by SARS-CoV-2 during COVID-19 (Corona Virus Disease 2019) in the early stage, stimulating ropy sputum drainage, and ultimately reducing the incidence of severe disease. Molecular hydrogen treatment has the potential to become a new adjuvant therapy for COVID-19, but its efficacy and safety require large clinical trials and further confirmation.

Hydrogen: A Novel Option in Human Disease Treatment

H₂ has shown anti-inflammatory and antioxidant ability in many clinical trials, and its application is recommended in the latest Chinese novel coronavirus pneumonia (NCP) treatment guidelines. Clinical experiments have revealed the surprising finding that H₂ gas may protect the lungs and extrapulmonary organs from pathological stimuli in NCP patients. The potential mechanisms underlying the action of H₂ gas are not clear. H₂ gas may regulate the anti-inflammatory and antioxidant activity, mitochondrial energy metabolism, endoplasmic reticulum stress, the immune system, and cell death (apoptosis, autophagy, pyroptosis, ferroptosis, and circadian clock, among others) and has therapeutic potential for many systemic diseases. This paper reviews the basic research and the latest clinical applications of H₂ gas in multiorgan system diseases to establish strategies for the clinical treatment for various diseases.

Prospects of molecular hydrogen in perioperative neuroprotection from basic research to clinical application

PURPOSE OF REVIEW

The current systematic review summarizes recent, basic clinical achievements regarding the neuroprotective effects of molecular hydrogen in distinct central nervous system conditions.

RECENT FINDINGS

Perioperative neuroprotection remains a major topic of clinical anesthesia. Various gaseous molecules have previously been explored as a feasible therapeutic option in neurological disorders. Among them, molecular hydrogen, which has emerged as a novel and potential therapy for perioperative neuroprotection, has received much attention.

SUMMARY

Fundamental and clinical evidence supports the antioxidant, antiinflammation, antiapoptosis and mitochondrial protective effects of hydrogen in the pathophysiology of nervous system diseases. The clinically preventive and therapeutic effects of hydrogen on different neural diseases, however, remain uncertain, and the lack of support by large randomized controlled trials has delayed its clinical application.

Sigh maneuver protects healthy lungs during mechanical ventilation in adult Wistar rats

Mechanical ventilation (MV) is a tool used for the treatment of patients with acute or chronic respiratory failure. However, MV is a non-physiological resource, and it can cause metabolic disorders such as release of pro-inflammatory cytokines and production of reactive oxygen species. In clinical setting, maneuvers such as sigh, are used to protect the lungs. Thus, this study aimed to evaluate the effects of sigh on oxidative stress and lung inflammation in healthy adult Wistar rats submitted to MV. Male Wistar rats were divided into four groups: control (CG), mechanical ventilation (MVG), MV set at 20 sighs/h (MVG20), and MV set at 40 sighs/h (MVG40). The MVG, MVG20, and MVG40 were submitted to MV for 1 h. After the protocol, all animals were euthanized and the blood, bronchoalveolar lavage fluid, and lungs were collected for subsequent analysis. In the arterial blood, MVG40 presented higher partial pressure of oxygen and lower partial pressure of carbon dioxide compared to control. The levels of bicarbonate in MVG20 were lower compared to CG. The neutrophil influx in bronchoalveolar lavage fluid was higher in the MVG compared to CG and MVG40. In the lung parenchyma, the lipid peroxidation was higher in MVG compared to CG, MVG20, and MVG40. Superoxide dismutase and catalase activity were higher in MVG compared to CG, MVG20, and MVG40. The levels of IL-1, IL-6, and TNF in the lung homogenate were higher in MVG compared to CG, MVG20, and MVG40. The use of sigh plays a protective role as it reduced redox imbalance and pulmonary inflammation caused by MV.

Hydrogen Attenuates Allergic Inflammation by Reversing Energy Metabolic Pathway Switch

Mechanisms mediating the protective effects of molecular hydrogen (H₂) are not well understood. This study explored the possibility that H₂ exerts its anti-inflammatory effect by modulating energy metabolic pathway switch. Activities of glycolytic and mitochondrial oxidative phosphorylation systems were assessed in asthmatic patients and in mouse model of allergic airway inflammation. The effects of hydrogen treatment on airway inflammation and on changes in activities of these two pathways were evaluated. Monocytes from asthmatic patients and lungs from ovalbumin-sensitized and challenged mice had increased lactate production and glycolytic enzyme activities (enhanced glycolysis), accompanied by decreased ATP production and mitochondrial respiratory chain complex I and III activities (suppressed mitochondrial oxidative phosphorylation), indicating an energy metabolic pathway switch. Treatment of ovalbumin-sensitized and challenged mice with hydrogen reversed the energy metabolic pathway switch, and mitigated airway inflammation. Hydrogen abrogated ovalbumin sensitization and challenge-induced upregulation of glycolytic enzymes and hypoxia-inducible factor-1α, and downregulation of mitochondrial respiratory chain complexes and peroxisome proliferator activated receptor-γ coactivator-1α. Hydrogen abrogated ovalbumin sensitization and challenge-induced sirtuins 1, 3, 5 and 6 downregulation. Our data demonstrates that allergic airway inflammation is associated with an energy metabolic pathway switch from oxidative phosphorylation to aerobic glycolysis. Hydrogen inhibits airway inflammation by reversing this switch. Hydrogen regulates energy metabolic reprogramming by acting at multiple levels in the energy metabolism regulation pathways.

The effects of gasotransmitters on bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD), which remains a major clinical problem for preterm infants, is caused mainly by hyperoxia, mechanical ventilation and inflammation. Many approaches have been developed with the aim of decreasing the incidence of or alleviating BPD, but effective methods are still lacking. Gasotransmitters, a type of small gas molecule that can be generated endogenously, exert a protective effect against BPD-associated lung injury; nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H₂S) are three such gasotransmitters. The protective effects of NO have been extensively studied in animal models of BPD, but the results of these studies are inconsistent with those of clinical trials. NO inhalation seems to have no effect on BPD, although side effects have been reported. NO inhalation is not recommended for BPD treatment in preterm infants, except those with severe pulmonary hypertension. Both CO and H₂S decreased lung injury in BPD rodent models in preclinical studies. Another small gas molecule, hydrogen, exerts a protective effect against BPD. The nuclear factor erythroid-derived 2 (Nrf2)/heme oxygenase-1 (HO-1) axis seems to play a central role in the protective effect of these gasotransmitters on BPD. Gasotransmitters play important roles in mammals, but further clinical trials are needed to explore their effects on BPD.

Endothelial Progenitor Cells Attenuate Ventilator-Induced Lung Injury with Large-Volume Ventilation

Ventilator-induced lung injury (VILI) is a common complication that results from treatment with mechanical ventilation (MV) in acute respiratory distress syndrome (ARDS) patients. The present study investigated the effect of endothelial progenitor cell (EPC) transplantation on VILI. Wistar rats were divided into three groups (n = 8): sham (S), VILI model (V) induced by tidal volume ventilation (17 mL/kg), and VILI plus EPC transplantation (VE) groups. The lung PaO₂/FiO₂ ratio, pulmonary wet-to-dry (W/D) weight ratio, number of neutrophils, total protein, neutrophil elastase level, and inflammatory cytokines in bronchoalveolar lavage fluid (BALF) and serum were examined. Furthermore, the histological and apoptotic analysis, and lung tissue protein expression analysis of Bax, Bcl-2, cleaved caspase-3, matrix metalloproteinase (MMP)-9, total nuclear factor kappa B (total-NF-κB), phosphorylated NF-κB (phospho-NF-κB) and myosin light chain (MLC) were performed. The ventilation-induced decrease in PaO₂/FiO₂ ratio, and the increase in W/D ratio and total protein concentration were prevented by the EPC transplantation. The EPC transplantation (VE group) significantly attenuated the VILI-induced increased expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-8, MMP-9, phospho-NF-κB and MLC, neutrophil elastase levels and neutrophil counts in BALF. In addition, the anti-inflammatory factor IL-10 increased in the VE group. Furthermore, pulmonary histological injury and apoptosis (TUNEL-positive cells, increase in Bax and cleaved caspase-3) were considerably diminished by the EPC transplantation. The EPC transplantation ameliorated the VILI. The mechanism may be primarily through the improvement of epithelial permeability, inhibition of local and systemic inflammation, and reduction in apoptosis.

Micro/Nanomaterials-Augmented Hydrogen Therapy

Hydrogen therapy is an emerging and promising therapy strategy of using molecular hydrogen as a new type of safe and effective therapeutic agent, exhibiting remarkable therapeutic effects on many oxidative stress-/inflammation-related diseases owing to its bio-reductivity and homeostatic regulation ability. Different from other gaseous transmitters such as NO, CO, and H₂ S, hydrogen gas has no blood poisoning risk at high concentration because it does not affect the oxygen-carrying behavior of blood red cells. Hydrogen molecules also have low aqueous solubility and high but aimless diffusibility, causing limited therapy efficacy in many diseases. To realize the site-specific hydrogen delivery, controlled hydrogen release and combined therapy is significant but still challenging. Here, a concept of hydrogen nanomedicine to address the issues of hydrogen medicine by using functional micro/nanomaterials for augmented hydrogen therapy is proposed. In this review, various strategies of micro/nanomaterials-augmented hydrogen therapy, including micro/nanomaterials-mediated targeted hydrogen delivery, controlled hydrogen release, and nanocatalytic and multimodel enhancement of hydrogen therapy efficacy, are summarized, which can open a new window for treatment of inflammation-related diseases.

Alpha 1-antitrypsin for treating ventilator-associated lung injury in acute respiratory distress syndrome rats

Purpose: Mechanical ventilation (MV) is an essential life support tool for patients with acute respiratory distress syndrome (ARDS). However, MV for ARDS can result in ventilator-induced lung injury (VILI). This study aimed to assess whether alpha 1-antitrypsin (AAT) can reduce VILI in ARDS rats. Materials and Methods: Rats were randomly divided into five groups: the sham (S) group, MV (V) group, lipopolysaccharide (LPS) (L) group, MV/LPS (VL) group and MV/AAT (VA) group. Rats in the S group were anesthetized. The rats in the L group received LPS but not ventilation, the rats in the V group received only MV, and the rats in the VL and VA groups received LPS and MV. Additionally, the rats in the VA group were treated with AAT, and the other rats were injected with saline. The PaO₂/FiO₂ ratio and the wet/dry weight were assessed. The total protein and neutrophil elastase concentrations and the neutrophil and macrophage counts in bronchoalveolar lavage fluid (BALF) were evaluated. Proinflammatory factors in BALF and ICAM-1 and MIP-2 in serum were also tested. Furthermore, the oxidative stress response was detected, and histological injury and apoptosis were evaluated. Results: All the rats in the V, L and VL groups had significant lung injury, with the VL group exhibiting the most severe injury. Compared with the findings in the VL group, AAT significantly upregulated the PaO₂/FiO₂ ratio but decreased the wet/dry weight ratio and protein levels in BALF. AAT also reduced proinflammatory cytokine levels and inflammatory cell counts in BALF. Lung tissue injury and cell apoptosis were mitigated by AAT. Conclusions: AAT ameliorated VILI in ARDS rats. The protection conferred by AAT may be associated with the anti-inflammatory, antioxidative stress response and anti-apoptotic effects of AAT.

Ligustrazin increases lung cell autophagy and ameliorates paraquat-induced pulmonary fibrosis by inhibiting PI3K/Akt/mTOR and hedgehog signalling via increasing miR-193a expression

Background

Reactive oxygen species (ROS) levels largely determine pulmonary fibrosis. Antioxidants have been found to ameliorate lung fibrosis after long-term paraquat (PQ) exposure. The effects of antioxidants, however, on the signalling pathways involved in PQ-induced lung fibrosis have not yet been investigated sufficiently. Here, we examined the impacts of ligustrazin on lung fibrosis, in particular ROS-related autophagy and pro-fibrotic signalling pathways, using a murine model of PQ-induced lung fibrosis.

Methods

We explored the effects of microRNA-193 (miR-193a) on Hedgehog (Hh) and PI3K/Akt/mTOR signalling and oxidative stress in lung tissues. Levels of miR-193a, protein kinase B (Akt), phosphoinositide 3-Kinase (PI3K), ceclin1, mammalian target of rapamycin (mTOR), sonic hedgehog (SHH), myosin-like Bcl2 interacting protein (LC3), smoothened (Smo), and glioma-associated oncogene-1 (Gli-1) mRNAs were determined with quantitative real-time PCR. Protein levels of PI3K, p-mTOR, p-Akt, SHH, beclin1, gGli-1, LC3, smo, transforming growth factor-β1 (TGF-β1), mothers against DPP homologue-2 (Smad2), connective tissue growth factor (CTGF), collagen I, collagen III, α-smooth muscle actin (α-SMA) nuclear factor erythroid 2p45-related factor-2 (Nrf2), and p-Smad2 were detected by western blotting. In addition, α-SMA, malondialdehyde, ROS, superoxide dismutase (SOD), oxidised and reduced glutathione, hydroxyproline, and overall collagen levels were identified in lung tissues using immunohistochemistry.

Results

Long-term PQ exposure blocked miR-193a expression, reduced PI3K/Akt/mTOR signalling, increased oxidative stress, inhibited autophagy, increased Hh signalling, and facilitated the formation of pulmonary fibrosis. Ligustrazin blocked PI3K/Akt/mTOR and Hh signalling as well as reduced oxidative stress via increasing miR-193a expression and autophagy, all of which reduced pulmonary fibrosis. These effects of ligustrazin were accompanied by reduced TGF-β1, CTGF, and Collagen I and III expression.

Conclusions

Ligustrazin blocked PQ-induced PI3K/Akt/mTOR and Hh signalling by increasing miR-193a expression, thereby attenuating PQ-induced lung fibrosis.

Role of glutamine in the mediation of E-cadherin, p120-catenin and inflammation in ventilator-induced lung injury

Background:

Ventilator-induced lung injury (VILI) is commonly associated with barrier dysfunction and inflammation reaction. Glutamine could ameliorate VILI, but its role has not been fully elucidated. This study examined the relationship between inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α, and IL-10) and adherens junctions (E-cadherin, p120-catenin), which were ameliorated by glutamine in VILI, both in vitro and in vivo.

Methods:

For the in vivo study, 30 healthy C57BL/6 mice weighing 25–30 g were randomly divided into five groups with random number table (n = 6 in each group): control (Group C); low tidal volume (Group L); low tidal volume + glutamine (Group L + G); high tidal volume (Group H); and high tidal volume + glutamine (Group H + G). Mice in all groups, except Group C, underwent mechanical ventilation for 4 h. For the in vitro study, mouse lung epithelial 12 (MLE-12) cells pretreated with glutamine underwent cyclic stretching at 20% for 4 h. Cell lysate and lung tissue were obtained to detect the junction proteins, inflammatory cytokines, and lung pathological changes by the Western blotting, cytokine assay, hematoxylin and eosin staining, and immunofluorescence.

Results:

In vivo, compared with Group C, total cell counts (t = −28.182, P < 0.01), the percentage of neutrophils (t = −28.095, P < 0.01), IL-6 (t = −28.296, P < 0.01), and TNF-α (t = −19.812, P < 0.01) in bronchoalveolar lavage (BAL) fluid, lung injury scores (t = −6.708, P < 0.01), and the wet-to-dry ratio (t = −15.595, P < 0.01) were increased in Group H; IL-10 in BAL fluid (t = 9.093, P < 0.01) and the expression of E-cadherin (t = 10.044, P < 0.01) and p120-catenin (t = 13.218, P < 0.01) were decreased in Group H. Compared with Group H, total cell counts (t = 14.844, P < 0.01), the percentage of neutrophils (t = 18.077, P < 0.01), IL-6 (t = 18.007, P < 0.01), and TNF-α (t = 10.171, P < 0.01) in BAL fluid were decreased in Group H + G; IL-10 in BAL fluid (t = −7.531, P < 0.01) and the expression of E-cadherin (t = −14.814, P < 0.01) and p120-catenin (t = −9.114, P < 0.01) were increased in Group H + G. In vitro, compared with the nonstretching group, the levels of IL-6 (t = −21.111, P < 0.01) and TNF-α (t = −15.270, P < 0.01) were increased in the 20% cyclic stretching group; the levels of IL-10 (t = 5.450, P < 0.01) and the expression of E-cadherin (t = 17.736, P < 0.01) and p120-catenin (t = 16.136, P < 0.01) were decreased in the 20% cyclic stretching group. Compared with the stretching group, the levels of IL-6 (t = 11.818, P < 0.01) and TNF-α (t = 8.631, P < 0.01) decreased in the glutamine group; the levels of IL-10 (t = −3.203, P < 0.05) and the expression of E-cadherin (t = −13.567, P < 0.01) and p120-catenin (t = −10.013, P < 0.01) were increased in the glutamine group.

Conclusions:

High tidal volume mechanical ventilation and 20% cyclic stretching could cause VILI. Glutamine regulates VILI by improving cytokines and increasing the adherens junctions, protein E-cadherin and p120-catenin, to enhance the epithelial barrier function.

Hydrogen Gas Does Not Ameliorate Renal Ischemia Reperfusion Injury in a Preclinical Model

In renal transplantation, ischemia reperfusion injury impairs early graft function and can reduce long term graft survival. Hydrogen has antioxidant and anti-inflammatory properties that can reduce the effects of ischemic injury. The aim of this study was to examine the effects of hydrogen gas administered during reperfusion in a preclinical model of kidney ischemia reperfusion injury. Porcine kidneys underwent 15 min of warm ischemia followed by 22 h of cold ischemia. They were then reperfused for 6 h with whole autologous blood on an ex vivo reperfusion circuit. Paired kidneys were randomized to control (n = 6) (25% oxygen, 5% carbon dioxide, 70% nitrogen) or hydrogen (n = 6) (2% hydrogen, 25% oxygen, 5% carbon dioxide, 68% nitrogen) groups. Tissue, urine, and blood samples were collected at baseline and hourly throughout the reperfusion period. Baseline measurements were similar across groups. Following perfusion, there was no significant difference between control and hydrogen groups in urine output (693 mL vs. 608 mL, P = 0.86), renal blood flow (105.9 vs. 108 mL/min/100g, P = 0.89), acid-base homeostasis, or creatinine clearance. There was a significant increase in cytokine levels from baseline to 6 h in both groups (IL-1β P = 0.002; IL-6 P = 0.004; IL-8 P = 0.002). However, there were no significant differences in levels of inflammatory cytokines (IL1β, IL-6, and IL-8) between the groups. The administration of hydrogen gas did not improve renal function, reduce oxidative damage, or inflammation during the reperfusion of ischemically damaged kidneys.

Mechanical ventilation promotes lung metastasis in experimental 4T1 breast cancer lung-metastasized models

BACKGROUND/PURPOSE

The aim of this study was to test the hypothesis that mechanical ventilation (MV) during cancer surgery induces lung stroma/tissue milieu changes, creating a favorable microenvironment for postoperative lung metastatic tumor establishment.

MATERIALS AND METHODS

In Protocol A, female BALB/c mice were divided into an MV group and a control (no MV) group, both of which were anesthetized and subjected to intravenous injection of green fluorescent protein (GFP)-labeled mouse mammary carcinoma cell line (4T1) cells. After 24 h, the lung tissue was removed and the number of GFP-labeled 4T1 cells was calculated. In Protocol B, the clinically relevant mouse model of spontaneous breast cancer lung metastasis was used with surgical resection of the primary tumor to investigate the MV event that dictates postoperative lung metastasis. Female BALB/c mice were inoculated in the mammary fat pad with 4T1 cells. After 14-d growth, mice were anesthetized and divided into an MV group and a control (no MV) group during surgical procedures (mastectomy). Metastatic tumor burden was assessed two weeks after mastectomy by both macroscopic metastatic nodule count, hematoxylin-eosin histology, immunohistochemistry for the macrophage marker (CD68), and epithelial cell adhesion molecule (EpCAM).

RESULTS

MV was associated with a significant increase in the number of circulating breast tumor cells (GFP-labeled 4T1 cells) remaining in the microvasculature of the lung (P<0.01). Immunohistochemical results showed increased infiltration of CD68-positive macrophages within injured lung parenchyma and metastatic tumor as well as increased expression of EpCAM in metastatic nodules. Postoperative metastases were more prevalent in the mechanically ventilated mice group compared to the non-ventilated group (P<0.05).

CONCLUSION

MV-induced lung metastasis occurs by attracting circulating tumor cells to the site of the lung injury and by accelerating the proliferation of preexisting micro-metastases in the lung. These observations indicate that the metastasis-enhancing effect of MV should be considered in general anesthesia during cancer surgery.

Desflurane Attenuates Ventilator-Induced Lung Injury in Rats with Acute Respiratory Distress Syndrome

Ventilator-induced lung injury aggravates the existing lung injury. This study investigated the effect of desflurane on VILI in a rat model of acute respiratory distress syndrome. Forty-eight rats were randomized into a sham (S) group, control (C) group, lipopolysaccharide/ventilation (LV) group, lipopolysaccharide/ventilation/desflurane (LVD) group, or lipopolysaccharide/low ventilation with and without desflurane (LLV and LLVD) groups. Rats in the S group received anesthesia only. Rats in the LV and LVD groups received lipopolysaccharide and were ventilated with a high tidal volume. Rats in LLV and LLVD groups were treated as the LV and LVD groups and ventilated with a low tidal volume. PaO₂/FiO₂, lung wet-to-dry weight ratios, concentrations of inflammatory factors in serum and BALF, histopathologic analysis of lung tissue, and levels of nuclear factor- (NF-) κB protein in lung tissue were investigated. PaO₂/FiO₂ was significantly increased by desflurane. Total cell count, macrophages, and neutrophils in BALF and proinflammatory factors in BALF and serum were significantly decreased by desflurane, while IL-10 was increased. The histopathological changes and levels of NF-κB protein in lung tissue were decreased by desflurane. The results indicated that desflurane ameliorated VILI in a rat model of acute respiratory distress syndrome.

Alpha 1-antitrypsin ameliorates ventilator-induced lung injury in rats by inhibiting inflammatory responses and apoptosis

Mechanical ventilation is extensively used to treat patients with lung injury but may result in ventilator-induced lung injury (VILI). The present study investigated the protective effect of alpha 1-antitrypsin (AAT) on VILI. Adult male rats were subjected to sham, ventilation + saline, or ventilation + AAT treatment and lung injuries were evaluated. Peripheral blood and bronchoalveolar lavage fluid (BALF) were obtained to assess systemic and local inflammatory responses, respectively. Mechanical ventilation resulted in lung injury, as evidenced by histological abnormalities as well as elevations in PaO₂/FiO₂ ratio, the wet-to-dry weight ratio, and the BALF level of proteins. The intravenous administration of AAT significantly improved these parameters of lung function, suggesting a protective role of AAT in VILI. Mechanistically, ventilator-induced inflammation was effectively reduced by AAT, as evidenced by decreases in BALF neutrophil counts, BALF cytokines, and serum adhesion factors. In contrast, anti-inflammatory interleukin-10 in BALF was increased in response to AAT. AAT treatment also inhibited the expression of nuclear factor-κB, Bax, and cleaved caspase-3 while promoting Bcl-2 expression in ventilator-injured lung tissues. AAT treatment can ameliorate VILI by inhibiting inflammatory mediator production and apoptosis. Impact statement Mechanical ventilation has been commonly used to treat patients with lung injury but may result in ventilator-induced lung injury (VILI). Few effective treatment options are currently available to reduce VILI. Alpha 1-antitrypsin (AAT) is an inhibitor of serine protease with anti-inflammatory and antiapoptotic properties, suggesting a possible role in attenuating lung injury. The present study demonstrates that AAT inhibits the development of VILI by modulating inflammation- and apoptosis-related protein expression. Therefore, AAT may be a novel therapeutic agent for acute respiratory distress syndrome patients undergoing mechanical ventilation.

Hydrogen coadministration slows the development of COPD-like lung disease in a cigarette smoke-induced rat model

Background

Chronic obstructive pulmonary disease (COPD) is a progressive pulmonary disease caused by harmful gases or particles. Recent studies have shown that 2% hydrogen or hydrogen water is effective in the treatment and prevention of a variety of diseases. This study investigated the beneficial effects and the possible mechanisms of different hydrogen concentrations on COPD.

Methods

A rat COPD model was established through smoke exposure methods, and inhalation of different concentrations of hydrogen was used as the intervention. The daily condition of rats and the weight changes were observed; lung function and right ventricular hypertrophy index were assessed. Also, white blood cells were assessed in bronchoalveolar lavage fluid. Pathologic changes in the lung tissue were analyzed using light microscopy and electron microscopy; cardiovascular structure and pulmonary arterial pressure changes in rats were observed using ultrasonography. Tumor necrosis factor alpha, interleukin (IL)-6, IL-17, IL-23, matrix metalloproteinase-12, tissue inhibitor of metalloproteinase-1, caspase-3, caspase-8 protein, and mRNA levels in the lung tissue were determined using immunohistochemistry, Western blot, and real-time polymerase chain reaction.

Results

The results showed that hydrogen inhalation significantly reduced the number of inflammatory cells in the bronchoalveolar lavage fluid, and the mRNA and protein expression levels of tumor necrosis factor alpha, IL-6, IL-17, IL-23, matrix metalloproteinase-12, caspase-3, and caspase-8, but increased the tissue inhibitor of metalloproteinase-1 expression. Furthermore, hydrogen inhalation ameliorated lung pathology, lung function, and cardiovascular function and reduced the right ventricular hypertrophy index. Inhalation of 22% and 41.6% hydrogen showed better outcome than inhalation of 2% hydrogen.

Conclusion

These results suggest that hydrogen inhalation slows the development of COPD-like lung disease in a cigarette smoke-induced rat model. Higher concentrations of hydrogen may represent a more effective way for the rat model.

Parecoxib reduced ventilation induced lung injury in acute respiratory distress syndrome

Background

Cyclooxygenase-2 (COX-2) contributes to ventilation induced lung injury (VILI) and acute respiratory distress syndrome (ARDS). The objective of present study was to observe the therapeutic effect of parecoxib on VILI in ARDS.

Methods

In this parallel controlled study performed at Harbin Medical University, China between January 2016 and March 2016, 24 rats were randomly allocated into sham group (S), volume ventilation group/ARDS (VA), parecoxib/volume ventilation group/ARDS (PVA). Rats in the S group only received anesthesia; rats in the VA and PVA group received intravenous injection of endotoxin to induce ARDS, and then received ventilation. Rats in the VA and PVA groups were treated with intravenous injection of saline or parecoxib. The ratio of arterial oxygen pressure to fractional inspired oxygen (PaO₂/FiO₂), the wet to dry weight ratio of lung tissue, inflammatory factors in serum and bronchoalveolar lavage fluid (BALF), and histopathologic analyses of lung tissue were examined. In addition, survival was calculated at 24 h after VILI.

Results

Compared to the VA group, in the PVA group, PaO₂/FiO₂ was significantly increased; lung tissue wet to dry weight ratio; macrophage and neutrophil counts, total protein and neutrophil elastase levels in BALF; tumor necrosis factor-α, interleukin-1β, and prostaglandin E₂ levels in BALF and serum; and myeloperoxidase (MPO) activity, malondialdehyde levels, and Bax and COX-2 protein levels in lung tissue were significantly decreased, while Bcl-2 protein levels were significantly increased. Lung histopathogical changes and apoptosis were reduced by parecpxib in the PVA group. Survival was increased in the PVA group.

Conclusions

Parecoxib improves gas exchange and epithelial permeability, decreases edema, reduces local and systemic inflammation, ameliorates lung injury and apoptosis, and increases survival in a rat model of VILI.

Hydrogen-rich water ameliorates bronchopulmonary dysplasia (BPD) in newborn rats

Bronchopulmonary dysplasia (BPD) is characterized by developmental arrest of the alveolar tissue. Oxidative stress is causally associated with development of BPD. The effects of hydrogen have been reported in a wide range of disease models and human diseases especially caused by oxidative stress. We made a rat model of BPD by injecting lipopolysaccharide (LPS) into the amniotic fluid at E16.5. The mother started drinking hydrogen-rich water from E9.5 and also while feeding milk. Hydrogen normalized LPS-induced abnormal enlargement of alveoli at P7 and P14. LPS increased staining for nitrotyrosine and 8-OHdG of the lungs, and hydrogen attenuated the staining. At P1, LPS treatment decreased expressions of genes for FGFR4, VEGFR2, and HO-1 in the lungs, and hydrogen increased expressions of these genes. In contrast, LPS treatment and hydrogen treatment had no essential effect on the expression of SOD1. Inflammatory marker proteins of TNFα and IL-6 were increased by LPS treatment, and hydrogen suppressed them. Treatment of A549 human lung adenocarcinoma epithelial cells with 10% hydrogen gas for 24 hr decreased production of reactive oxygen species in both LPS-treated and untreated cells. Lack of any known adverse effects of hydrogen makes hydrogen a promising therapeutic modality for BPD. Pediatr Pulmonol. 2016; 51:928-935. © 2016 Wiley Periodicals, Inc.

Role of the PKCα-c-Src tyrosine kinase pathway in the mediation of p120-catenin degradation in ventilator-induced lung injury

BACKGROUND AND OBJECTIVE

Ventilator-induced lung injury (VILI) is commonly associated with respiratory barrier dysfunction; however, the mechanisms have not been fully elucidated. This study aimed to determine the order and components of the signalling pathway that mediates the degradation of adherin junction of p120-catenin in VILI.

METHODS

For the in vivo study, C57BL/6 mice were pre-treated with inhibitors for 60 min prior to 4 h of mechanical ventilation. For the in vitro study, mouse lung epithelial 12 (MLE-12) cells were pre-treated with inhibitors for 60 min or small interfering RNA (siRNA) for 48 h prior to cyclic stretch at 20% for 4 h. The protein levels of protein kinase Cα (PKCα), activated c-Src and p120-catenin were determined via western blot analysis. Lung injury was determined via HE staining, immunofluorescence, wet/dry ratio and lung injury scores.

RESULTS

High tidal volume mechanical ventilation and 20% cyclic stretch resulted in the degradation of p120-catenin. Inhibitors of PKCα blocked c-Src kinase activation and p120-catenin degradation in VILI. Inhibitors of c-Src kinase or PP2 or siRNA blocked p120-catenin degradation but not PKCα activation.

CONCLUSION

The current findings demonstrates that PKCα and c-Src kinase participate in VILI. PKCα activation phosphorylates c-Src kinase and further decreases p120-catenin in VILI.

Mucosal fluid evaporation is not the method of heat dissipation from fourth-degree laryngopharyngeal burns

This study was designed to explore whether mucosal fluid evaporation represents a method of heat dissipation from thermal air inhalation injury and to assess laryngopharyngeal tissue damage according to heat quantity changes of dry air and vapour. Fifteen adult male beagles were divided into five groups to inhale heated air or vapour for 10 min as follows: control group (ordinary air), group I (91–110 °C heated air), group II (148–175 °C heated air), group III (209–227 °C heated air), and group IV (96 °C saturated vapour). The heat quantity changes of the dry air and vapour were calculated via thermodynamic formulas. The macroscopic and histological features of the laryngopharynxes were examined and assessed by various tissue damage grading systems. Group IV exhibited the most serious laryngopharyngeal damage, including cilia exfoliation, submucosal thrombosis, glandular atrophy, and chondrocyte degeneration, which is indicative of fourth-degree injury. The quality, heat quantity, and proportional reduction of heat quantity of vapour in group IV were all higher than those in the other groups. Furthermore, we found that mucosal fluid evaporation is not the method of heat dissipation from thermal air inhalation injury used by the airways. Laryngopharyngeal tissue damage depends chiefly on the heat quantity of vapour in the air.

Current Antioxidant Treatments in Organ Transplantation

Oxidative stress is one of the key mechanisms affecting the outcome throughout the course of organ transplantation. It is widely believed that the redox balance is dysregulated during ischemia and reperfusion (I/R) and causes subsequent oxidative injury, resulting from the formation of reactive oxygen species (ROS). Moreover, in order to alleviate organ shortage, increasing number of grafts is retrieved from fatty, older, and even non-heart-beating donors that are particularly vulnerable to the accumulation of ROS. To improve the viability of grafts and reduce the risk of posttransplant dysfunction, a large number of studies have been done focusing on the antioxidant treatments for the purpose of maintaining the redox balance and thereby protecting the grafts. This review provides an overview of these emerging antioxidant treatments, targeting donor, graft preservation, and recipient as well.

Inhaled hydrogen ameliorates endotoxin-induced bowel dysfunction

Aim

Gastrointestinal dysmotility frequently occurs during sepsis and multiple organ failure, remaining a major cause of morbidity and mortality in critically ill patients. Previous studies have shown that hydrogen, a new therapeutic gas, can improve various organ damage associated with sepsis. In this study, we investigated the protective efficacies of inhaled hydrogen against lipopolysaccharide (LPS)‐induced ileus.

Methods

Sepsis was induced in rats and mice by a single i.p. injection of LPS at 15 mg/kg for mice and 5 mg/kg for rats. Four groups of rats and mice including sham/air, sham/hydrogen, LPS/air, and LPS/hydrogen were analyzed. Hydrogen (1.3%) was inhaled for 25 h beginning at 1 h prior to LPS treatment. Gastrointestinal transit was quantified and cytokine levels, as well as neutrophil extravasation, in the intestinal muscularis propria were determined.

Results

Lipopolysaccharide challenge remarkably delayed gastrointestinal transit of non‐absorbable dextran, associated with increased leukocyte recruitment and upregulation of pro‐inflammatory cytokine mRNA expressions in the muscularis propria. Hydrogen significantly prevented LPS‐induced bowel dysmotility and reduced leukocyte extravasation, as well as inhibition of inflammatory cytokine expression. In vitro analysis of cytokine levels after LPS treatment of cultured macrophages showed an increase of interleukin‐10 by hydrogen regardless of the presence of nitric oxide.

Conclusions

This study showed the protective effects of hydrogen inhalation on LPS‐induced septic ileus through inhibition of inflammation in the muscularis propria. These inhibitory effects on the pro‐inflammatory response may be partially derived from anti‐inflammatory cytokine interleukin‐10 induction.

Budesonide ameliorates lung injury induced by large volume ventilation

Background

Ventilation-induced lung injury (VILI) is a health problem for patients with acute respiratory dysfunction syndrome. The aim of this study was to investigate the effectiveness of budesonide in treating VILI.

Methods

Twenty-four rats were randomized to three groups: a ventilation group, ventilation/budesonide group, and sham group were ventilated with 30 ml/kg tidal volume or only anesthesia for 4 hor saline or budesonide airway instillation immediately after ventilation. The PaO₂/FiO₂and wet-to-dry weight ratios, protein concentration, neutrophil count, and neutrophil elastase levels in bronchoalveolar lavage fluid (BALF) and the levels of inflammation-related factors were examined. Histological evaluation of and apoptosis measurement inthe lung were conducted.

Results

Compared with that in the ventilation group, the PaO₂/FiO₂ ratio was significantly increased by treatment with budesonide. The lung wet-to-dry weight ratio, total protein, neutrophil elastase level, and neutrophilcount in BALF were decreased in the budesonide group. The BALF and plasma tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, intercellular adhesion molecule (ICAM)-1, and macrophage inflammatory protein (MIP)-2 levels were decreased, whereas the IL-10 level was increased in the budesonide group. The phosphorylated nuclear factor (NF)-kBlevels in lung tissue were inhibited by budesonide. The histological changes in the lung and apoptosis were reduced by budesonide treatment. Bax, caspase-3, and cleaved caspase-3 were down-regulated, and Bcl-2 was up-regulated by budesonide.

Conclusions

Budesonide ameliorated lung injury induced by large volume ventilation, likely by improving epithelial permeability, decreasing edema, inhibiting local and systemic inflammation, and reducing apoptosis in VILI.

Combination therapy with nitric oxide and molecular hydrogen in a murine model of acute lung injury

Acute lung injury (ALI) is still a leading cause of morbidity and mortality in critically ill patients. Inhaled nitric oxide (NO) has been reported to ameliorate ALI. However, reactive nitrogen species produced by NO can cause lung injury. Because hydrogen gas (H2) is reported to eliminate peroxynitrite, it is expected to reduce the adverse effects of NO. Moreover, we have found that H2 inhalation can attenuate lung injury. Therefore, we hypothesized that combination therapy with NO and H2 might afford more potent therapeutic strategies for ALI. In the present study, a mouse model of ALI was induced by intratracheal administration of lipopolysaccharide (LPS). The animals were treated with inhaled NO (20 ppm), H2 (2%), or NO + H2, starting 5 min after LPS administration for 3 h. We found that LPS-challenged mice exhibited significant lung injury characterized by the deterioration of histopathology and histologic scores, wet-to-dry weight ratio, and oxygenation index (ratio of oxygen tension to inspired oxygen fraction [Pao2/Fio2]), as well as total protein in the bronchoalveolar lavage fluid (BALF), which was attenuated by NO or H2 treatment alone. Combination therapy with NO and H2 had a more beneficial effect with significant interaction between the two. While the nitrotyrosine level in lung tissue was prominent after NO inhalation alone, it was significantly eliminated after breathing a mixture of NO with H2. Furthermore, NO or H2 treatment alone markedly attenuated LPS-induced lung neutrophil recruitment and inflammation, as evidenced by downregulation of lung myeloperoxidase activity, total cells, and polymorphonuclear neutrophils in BALF, as well as proinflammatory cytokines (tumor necrosis factor α, interleukins 1β and 6, and high-mobility group box 1) and chemokines (keratinocyte-derived chemokine, macrophage inflammatory proteins 1α and 2, and monocyte chemoattractant protein 1) in BALF. Combination therapy with NO and H2 had a more beneficial effect against lung inflammatory response. Moreover, combination therapy with NO and H2 could more effectively inhibit LPS-induced pulmonary early and late nuclear factor κB activation as well as pulmonary cell apoptosis. In addition, combination treatment with inhaled NO and H2 could also significantly attenuate lung injury in polymicrobial sepsis. Combination therapy with subthreshold concentrations of NO and H2 still had a significantly beneficial effect against lung injury induced by LPS and polymicrobial sepsis. Collectively, these results demonstrate that combination therapy with NO and H2 provides enhanced therapeutic efficacy for ALI.

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.