Lung inflation with hydrogen during the cold ischemia phase decreases lung graft injury in rats

Nrf2/HO-1 Pathway Mediated Protective Effects of Hydrogen in a Model of Lung Transplantation Simulated by Rat Pulmonary Microvascular Endothelial Cells

This study aimed to observe the mechanism of hydrogen (H2) in a lung transplantation model simulated by pulmonary microvascular endothelial cells (PMVECs), which were divided into 5 groups. The blank group was the normal PMVECs. During cold ischemia period, PMVECs in the control, O2, or H2 groups were aerated with no gas, O2, or 3% H2, and 3% H2 after transfected with a small interfering RNA targeting Nrf2 in the H2+si-Nrf2 group. Treatment with O2 and H2 decreased the oxidative stress injury, inflammation, cell apoptosis, and attenuated energy metabolism compared with the control group (P < 0.05). And the H2 group showed a better outcome with the increased protein expression of the Nrf2 and HO-1, which were conversed in the H2+si-Nrf2 group. In conclusion, H2 attenuated inflammation, oxidative stress injury, cell apoptosis, and maintained the balance between energy supply and demand in a rat PMVECs lung transplantation model via Nrf2/HO-1.

Design, synthesis, and biological evaluation of oridonin derivatives as novel NLRP3 inflammasome inhibitors for the treatment of acute lung injury

Acute lung injury (ALI) is a severe respiratory disorder closely associated with the excessive activation of the NLRP3 inflammasome. Oridonin (Ori), a natural diterpenoid compound, had been confirmed as a specific covalent NLRP3 inflammasome inhibitor, which was completely different from that of MCC950. However, the further clinical application of Ori was limited by its weak inhibitory activity against NLRP3 inflammasome (IC50 = 1240.67 nM). Fortunately, through systematic structure-optimization of Ori, D6 demonstrated the enhancement of IL-1β inhibitory activity (IC50 = 41.79 nM), which was better than the parent compound Ori. Then, by using SPR, molecular docking and MD simulation, D6 was verified to directly interact with NLRP3 via covalent and non-covalent interaction. The further anti-inflammatory mechanism studies were revealed that D6 could inhibit the activation of NLRP3 inflammasome without affecting the initiation phase of NLRP3 inflammasome activation, and D6 was a broad-spectrum and selective NLRP3 inflammasome inhibitor. Finally, D6 demonstrated a favorable therapeutic effect on LPS-induced ALI in mice model, and the potent pharmacodynamic effect of D6 was correlated with the specific inhibition of NLRP3 inflammasome activation in vivo. Thus, D6 is proved as a potent NLRP3 inhibitor, and has the potential to develop as a novel anti-ALI agent.

Hibernating/Awakening Nanomotors Promote Highly Efficient Cryopreservation by Limiting Ice Crystals

The disruptions caused by ice crystal formation during the cryopreservation of cells and tissues can cause cell and tissue damage. Thus, preventing such damage during cryopreservation is an important but challenging goal. Here, a hibernating/awakening nanomotor with magnesium/palladium covering one side of a silica platform (Mg@Pd@SiO2) is proposed. This nanomotor is used in the cultivation of live NCM460 cells to demonstrate a new method to actively limit ice crystal formation and enable highly efficient cryopreservation. Cooling Mg@Pd@SiO2 in solution releases Mg2+/H2 and promotes the adsorption of H2 at multiple Pd binding sites on the cell surface to inhibit ice crystal formation and cell/tissue damage; additionally, the Pd adsorbs and stores H2 to form a hibernating nanomotor. During laser-mediated heating, the hibernating nanomotor is activated (awakened) and releases H2, which further suppresses recrystallization and decreases cell/tissue damage. These hibernating/awakening nanomotors have great potential for promoting highly efficient cryopreservation by inhibiting ice crystal formation.

The Protective Role of Molecular Hydrogen in Ischemia/Reperfusion Injury

Ischemia/reperfusion injury (IRI) represents a significant contributor to morbidity and mortality associated with various clinical conditions, including acute coronary syndrome, stroke, and organ transplantation. During ischemia, a profound hypoxic insult develops, resulting in cellular dysfunction and tissue damage. Paradoxically, reperfusion can exacerbate this injury through the generation of reactive oxygen species and the induction of inflammatory cascades. The extensive clinical sequelae of IRI necessitate the development of therapeutic strategies to mitigate its deleterious effects. This has become a cornerstone of ongoing research efforts in both basic and translational science. This review examines the use of molecular hydrogen for IRI in different organs and explores the underlying mechanisms of its action. Molecular hydrogen is a selective antioxidant with anti-inflammatory, cytoprotective, and signal-modulatory properties. It has been shown to be effective at mitigating IRI in different models, including heart failure, cerebral stroke, transplantation, and surgical interventions. Hydrogen reduces IRI via different mechanisms, like the suppression of oxidative stress and inflammation, the enhancement of ATP production, decreasing calcium overload, regulating cell death, etc. Further research is still needed to integrate the use of molecular hydrogen into clinical practice.

Penehyclidine hydrochloride alleviates lung ischemia-reperfusion injury by inhibiting pyroptosis

OBJECTIVE

The aim of this research was to examine how penehyclidine hydrochloride (PHC) impacts the occurrence of pyroptosis in lung tissue cells within a rat model of lung ischemia-reperfusion injury.

METHODS

Twenty-four Sprague Dawley (SD) rats, weighing 250 g to 270 g, were randomly distributed into three distinct groups as outlined below: a sham operation group (S group), a control group (C group), and a test group (PHC group). Rats in the PHC group received a preliminary intravenous injection of PHC at a dose of 3 mg/kg. At the conclusion of the experiment, lung tissue and blood samples were collected and properly stored for subsequent analysis. The levels of malondialdehyde, superoxide dismutase, and myeloperoxidase in the lung tissue, as well as IL-18 and IL-1β in the blood serum, were assessed using an Elisa kit. Pyroptosis-related proteins, including Caspase1 p20, GSDMD-N, and NLRP3, were detected through the western blot method. Additionally, the dry-to-wet ratio (D/W) of the lung tissue and the findings from the blood gas analysis were also documented.

RESULTS

In contrast to the control group, the PHC group showed enhancements in oxygenation metrics, reductions in oxidative stress and inflammatory reactions, and a decrease in lung injury. Additionally, the PHC group exhibited lowered levels of pyroptosis-associated proteins, including the N-terminal segment of gasdermin D (GSDMD-N), caspase-1p20, and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3).

CONCLUSION

Pre-administration of PHC has the potential to mitigate lung ischemia-reperfusion injuries by suppressing the pyroptosis of lung tissue cells, diminishing inflammatory reactions, and enhancing lung function. The primary mechanism behind anti-pyroptotic effect of PHC appears to involve the inhibition of oxidative stress.

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: A Rising Star in Gas Medicine as a Mitochondria-Targeting Nutrient via Activating Keap1-Nrf2 Antioxidant System

The gas molecules O2, NO, H2S, CO, and CH4, have been increasingly used for medical purposes. Other than these gas molecules, H2 is the smallest diatomic molecule in nature and has become a rising star in gas medicine in the past few decades. As a non-toxic and easily accessible gas, H2 has shown preventive and therapeutic effects on various diseases of the respiratory, cardiovascular, central nervous system, and other systems, but the mechanisms are still unclear and even controversial, especially the mechanism of H2 as a selective radical scavenger. Mitochondria are the main organelles regulating energy metabolism in living organisms as well as the main organelle of reactive oxygen species' generation and targeting. We propose that the protective role of H2 may be mainly dependent on its unique ability to penetrate every aspect of cells to regulate mitochondrial homeostasis by activating the Keap1-Nrf2 phase II antioxidant system rather than its direct free radical scavenging activity. In this review, we summarize the protective effects and focus on the mechanism of H2 as a mitochondria-targeting nutrient by activating the Keap1-Nrf2 system in different disease models. In addition, we wish to provide a more rational theoretical support for the medical applications of hydrogen.

Diallyl disulfide attenuates pyroptosis via NLRP3/Caspase-1/IL-1β signaling pathway to exert a protective effect on hypoxic-ischemic brain damage in neonatal rats

Hypoxic-ischemic encephalopathy (HIE) is a perinatal brain disease caused by hypoxia in neonates. It is one of the leading causes of neonatal death in the perinatal period, as well as disability beyond the neonatal period. Due to the lack of a unified and comprehensive treatment strategy for HIE, research into its pathogenesis is essential. Diallyl disulfide (DADS) is an allicin extract, with detoxifying, antibacterial, and cardiovascular disease protective effects. This study aimed to determine whether DADS can alleviate HIE induced brain damage in rats and oxygen-glucose deprivation (OGD)-induced pyroptosis in PC12 cells, as well as whether it can inhibit pyroptosis via the NLRP3/Caspase-1/IL-1β signaling pathway. In vivo, DADS significantly reduced the cerebral infarction volume, alleviated inflammatory reaction, reduced astrocyte activation, promoted tissue structure recovery, improved pyroptosis caused by HIE and improved the prognosis following HI injury. In vitro findings indicated that DADS increased cell activity, decreased LDH activity and reduced the expression of pyroptosis-related proteins, including IL-1β, IL-18, and certain inflammatory factors in PC12 cells caused by OGD. Mechanistically, DADS inhibited pyroptosis and protected against HIE via the NLRP3/Caspase-1/IL-1β pathway. The specific inhibitor of caspase-1, VX-765, inhibited caspase-1 activation, and IL-1β expression was determined. Additionally, the overexpression of NLRP3 reversed the protective effect of allicin against OGD-induced pyroptosis. In conclusion, these findings demonstrated that DADS inhibits the NLRP3/Caspase-1/IL-1β signaling pathway and decreases HI brain damage.

Inflation using hydrogen improves donor lung quality by regulating mitochondrial function during cold ischemia phase

BACKGROUND

Mitochondrial dysfunction results in poor organ quality, negatively affecting the outcomes of lung transplantation. Whether hydrogen benefits mitochondrial function in cold-preserved donors remain unclear. The present study assessed the effect of hydrogen on mitochondrial dysfunction in donor lung injury during cold ischemia phase (CIP) and explored the underlying regulatory mechanism.

METHODS

Left donor lungs were inflated using 40% oxygen + 60% nitrogen (O group), or 3% hydrogen + 40% oxygen + 57% nitrogen (H group). Donor lungs were deflated in the control group and were harvested immediately after perfusion in the sham group (n = 10). Inflammation, oxidative stress, apoptosis, histological changes, mitochondrial energy metabolism, and mitochondrial structure and function were assessed. The expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were also analyzed.

RESULTS

Compared with the sham group, inflammatory response, oxidative stress, histopathological changes, and mitochondrial damage were severe in the other three groups. However, these injury indexes were remarkably decreased in O and H groups, with increased Nrf2 and HO-1 levels, elevated mitochondrial biosynthesis, inhibition of anaerobic glycolysis and restored mitochondrial structure and function compared with the control group. Moreover, inflation using hydrogen contributed to stronger protection against mitochondrial dysfunction and higher levels of Nrf2 and HO-1 when comparing with O group.

CONCLUSIONS

Lung inflation using hydrogen during CIP may improve donor lung quality by mitigating mitochondrial structural anomalies, enhancing mitochondrial function, and alleviating oxidative stress, inflammation, and apoptosis, which may be achieved through activation of the Nrf2/HO-1 pathway.

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: Potential Applications in Solid Organ Transplantation

Ischemia reperfusion injury (IRI) in organ transplantation has always been an important hotspot in organ protection. Hydrogen, as an antioxidant, has been shown to have anti-inflammatory, antioxidant, and antiapoptotic effects. In this paper, the protective effect of hydrogen against IRI in organ transplantation has been reviewed to provide clues for future clinical studies.

Lung Inflation With Hydrogen During the Cold Ischemia Phase Alleviates Lung Ischemia-Reperfusion Injury by Inhibiting Pyroptosis in Rats

Background: Lung inflation with hydrogen is an effective method to protect donor lungs from lung ischemia-reperfusion injury (IRI). This study aimed to examine the effect of lung inflation with 3% hydrogen during the cold ischemia phase on pyroptosis in lung grafts of rats.

Methods: Adult male Wistar rats were randomly divided into the sham group, the control group, the oxygen (O₂) group, and the hydrogen (H₂) group. The sham group underwent thoracotomy but no lung transplantation. In the control group, the donor lungs were deflated for 2 h. In the O₂ and H₂ groups, the donor lungs were inflated with 40% O₂ + 60% N₂ and 3% H₂ + 40% O₂ + 57% N₂, respectively, at 10 ml/kg, and the gas was replaced every 20 min during the cold ischemia phase for 2 h. Two hours after orthotopic lung transplantation, the recipients were euthanized.

Results: Compared with the control group, the O₂ and H₂ groups improved oxygenation indices, decreases the inflammatory response and oxidative stress, reduced lung injury, and improved pressure-volume (P-V) curves. H₂ had a better protective effect than O₂. Furthermore, the levels of the pyroptosis-related proteins selective nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), cysteinyl aspartate specific proteinase (caspase)-1 p20, and the N-terminal of gasdermin D (GSDMD-N) were decreased in the H₂ group.

Conclusion: Lung inflation with 3% hydrogen during the cold ischemia phase inhibited the inflammatory response, oxidative stress, and pyroptosis and improved the function of the graft. Inhibiting reactive oxygen species (ROS) production may be the main mechanism of the antipyroptotic effect of hydrogen.

Protective effects of molecular hydrogen on lung injury from lung transplantation

Lung grafts may experience multiple injuries during lung transplantation, such as warm ischaemia, cold ischaemia, and reperfusion injury. These injuries all contribute to primary graft dysfunction, which is a major cause of morbidity and mortality after lung transplantation. As a potential selective antioxidant, hydrogen molecule (H₂) protects against post-transplant complications in animal models of multiple organ transplantation. Herein, the authors review the current literature regarding the effects of H₂ on lung injury from lung transplantation. The reviewed studies showed that H₂ improved the outcomes of lung transplantation by decreasing oxidative stress and inflammation at the donor and recipient phases. H₂ is primarily administered via inhalation, drinking hydrogen-rich water, hydrogen-rich saline injection, or a hydrogen-rich water bath. H₂ favorably modulates signal transduction and gene expression, resulting in the suppression of pro-inflammatory cytokines and excess reactive oxygen species production. Although H₂ appears to be a physiological regulatory molecule with antioxidant, anti-inflammatory and anti-apoptotic properties, its exact mechanisms of action remain elusive. Taken together, accumulating experimental evidence indicates that H₂ can significantly alleviate transplantation-related lung injury, mainly via inhibition of inflammatory cytokine secretion and reduction in oxidative stress through several underlying mechanisms. Further animal experiments and preliminary human clinical trials will lay the foundation for the use of H₂ as a treatment in the clinic.

Oxymatrine exerts a protective effect in myocardial ischemia/reperfusion‑induced acute lung injury by inhibiting autophagy in diabetic rats

Oxymatrine (OMT) is the primary active component of Sophora flavescens Ait., and is widely used for the treatment of diabetic complications. The present study aimed to investigate the effects of OMT on acute lung injury (ALI) in diabetic rats subjected to myocardial ischemia/reperfusion (I/R). ALI in a myocardial I/R model was established in streptozocin‑induced diabetic rats. Enzyme‑linked immunosorbent assays were used to evaluate the levels of creatine kinase isoenzyme MB and lactate dehydrogenase, and the inflammatory response was assessed via leukocyte counts and the levels of tumor necrosis factor (TNF)‑α, interleukin (IL)‑6 and IL‑8 in the bronchoalveolar lavage (BAL) fluid. Hematoxylin and eosin staining was used to determine pathological changes to the lung tissue, and the autophagy‑related proteins LC‑3II/LC‑3I, Beclin‑1, autophagy protein 5 (Atg5) and p62 were detected by western blotting. Diabetic rats subjected to myocardial I/R showed increased levels of ALI with a higher lung injury score and WET/DRY ratio, and lower partial pressure of oxygen. This was accompanied by aberrant autophagy, indicated by an increased LC‑3II/LC‑3I ratio, decreased p62 expression levels, increased Atg5 and beclin‑1 expression levels, decreased superoxide dismutase activity and increased 15‑F2t‑isoprostane formation in lung tissues, as well as increased levels of leukocytes, TNF‑α, IL‑6 and IL‑8 in the BAL fluid. Administration of the autophagy inducer rapamycin significantly accelerated these alterations, while the autophagy inhibitor 3‑Methyladenine exerted the opposite effects. These results indicated that diabetic lungs are more vulnerable to myocardial I/R, which was associated with aberrant autophagy. Furthermore, oxymatrine was observed to reverse and alleviate ALI in diabetic rats with myocardial I/R in a concentration‑dependent manner, the mechanism of which may be associated with the inhibition of autophagy.

Review 1: Lung transplant-from donor selection to graft preparation

For various end-stage lung diseases, lung transplantation remains one of the only viable treatment options. While the demand for lung transplantation has steadily risen over the last few decades, the availability of donor grafts is limited, which have resulted in progressively longer waiting lists. In the early years of lung transplantation, only the 'ideal' donor grafts are considered for transplantation. Due to the donor shortages, there is ongoing discussion about the safe use of 'suboptimal' grafts to expand the donor pool. In this review, we will discuss the considerations around donor selection, donor-recipient matching, graft preparation and graft optimisation.

Review 2: Primary graft dysfunction after lung transplant-pathophysiology, clinical considerations and therapeutic targets

Primary graft dysfunction (PGD) is one of the most common complications in the early postoperative period and is the most common cause of death in the first postoperative month. The underlying pathophysiology is thought to be the ischaemia–reperfusion injury that occurs during the storage and reperfusion of the lung engraftment; this triggers a cascade of pathological changes, which result in pulmonary vascular dysfunction and loss of the normal alveolar architecture. There are a number of surgical and anaesthetic factors which may be related to the development of PGD. To date, although treatment options for PGD are limited, there are several promising experimental therapeutic targets. In this review, we will discuss the pathophysiology, clinical management and potential therapeutic targets of PGD.

Expression and regulation of tumor necrosis factor-α-induced protein-8-like 2 is associated with acute lung injury induced by myocardial ischemia reperfusion in diabetic rats

AIMS

The purpose of the present study was to investigate the possible role of TIPE2 on acute lung injury (ALI) induced by myocardial ischemia/reperfusion (MIR) in diabetic rats.

METHODS

Sprague-Dawley (SD) rats were randomly separated into four groups: control+sham (C + sham); control+MIR (C + MIR); diabetes+sham (D + sham); diabetes+MIR (D + MIR). Diabetes was induced using streptozotocin. Eight weeks after diabetes induction, MIR was conducted. At 2 h after MIR, myocardial injury indices were assessed; arterial blood, bronchoalveolar lavage fluid (BALF) and lung tissues were collected for corresponding detection.

RESULTS

Rats subjected to MIR showed serious ALI (estimated via pathological changes, lung injury score and Wet/Dry weight ratio), lung inflammation and pulmonary cell apoptosis compared with sham groups, especially in D + MIR group. Evaluation of protein expression in lung tissues showed that p-JNK and nuclear NF-κB p65 protein levels were higher in D + MIR group as compared with C + MIR group. Besides, either hyperglycemia or MIR can significantly upregulate TIPE2 protein levels.

CONCLUSIONS

In conclusion, diabetic lungs are more susceptible to MIR. TIPE2 may involve in this pathological process, possibly through regulation of inflammation, oxidative stress and apoptosis.

Hydrogen water alleviates obliterative airway disease in mice

OBJECTIVE

Bronchiolitis obliterans syndrome arising from chronic airway inflammation is a leading cause of death following lung transplantation. Several studies have suggested that inhaled hydrogen can protect lung grafts from ischemia-reperfusion injury via anti-inflammatory and -oxidative mechanisms. We investigated whether molecular hydrogen-saturated water can preserve lung allograft function in a heterotopic tracheal allograft mouse model of obliterative airway disease METHODS: Obliterative airway disease was induced by heterotopically transplanting tracheal allografts from BALB/c donor mice into C57BL/6 recipient mice, which were subsequently administered hydrogen water (10 ppm) or tap water (control group) (n = 6 each) daily without any immunosuppressive treatment. Histological and immunohistochemical analyses were performed on days 7, 14, and 21.

RESULTS

Hydrogen water decreased airway occlusion on day 14. No significant histological differences were observed on days 7 or 21. The cluster of differentiation 4/cluster of differentiation 3 ratio in tracheal allografts on day 14 was higher in the hydrogen water group than in control mice. Enzyme-linked immunosorbent assay performed on day 7 revealed that hydrogen water reduced the level of the pro-inflammatory cytokine interleukin-6 and increased that of forkhead box P3 transcription factor, suggesting an enhancement of regulatory T cell activity.

CONCLUSIONS

Hydrogen water suppressed the development of mid-term obliterative airway disease in a mouse tracheal allograft model via anti-oxidant and -inflammatory mechanisms and through the activation of Tregs. Thus, hydrogen water is a potential treatment strategy for BOS that can improve the outcome of lung transplant patients.

Protective effects of hydrogen inhalation during the warm ischemia phase against lung ischemia-reperfusion injury in rat donors after cardiac death

BACKGROUND

Successful amelioration of long-term warm ischemia lung injury in donors after cardiac death (DCDs) can remarkably improve outcomes. Hydrogen gas provides potent anti-inflammatory and antioxidant effects against ischemia-reperfusion injury (IRI). This study observed the effects of hydrogen inhalation on lung grafts during the warm ischemia phase in cardiac death donors.

METHODS

After cardiac death, rat donor lungs (n = 8) underwent mechanical ventilation with 40% oxygen plus 60% nitrogen (control group) or 3% hydrogen and 40% oxygen plus 57% nitrogen (hydrogen group) for 2 h during the warm ischemia phase in situ. Then, lung transplantation was performed after 2 h of cold storage and 3 h of recipient reperfusion prior to lung graft assessment. Rats that underwent left thoracotomy without transplantation served as the sham group (n = 8). The results of static compliance and arterial blood gas analysis were assessed in the recipients. The wet-to-dry weight ratio (W/D), inflammation, oxidative stress, cell apoptosis and histologic changes were evaluated after 3 h of reperfusion. Nuclear factor kappa B (NF-κB) protein expression in the graft was analyzed by Western blotting.

RESULTS

Compared with the sham group, lung function, W/D, inflammatory reaction, oxidative stress and histological changes were decreased in both transplant groups (control and hydrogen groups). However, compared with the control group, exposure to 3% hydrogen significantly improved lung graft static compliance and oxygenation and remarkably decreased the wet-to-dry weight ratio, inflammatory reactions, and lipid peroxidation. Furthermore, hydrogen improved the lung graft histological changes, decreased the lung injury score and apoptotic index and reduced NF-κB nuclear accumulation in the lung grafts.

CONCLUSION

Lung inhalation with 3% hydrogen during the warm ischemia phase attenuated lung graft IRI via NF-κB-dependent anti-inflammatory and antioxidative effects in rat donors after cardiac death.

Hydrogen and Oxygen Mixture to Improve Cardiac Dysfunction and Myocardial Pathological Changes Induced by Intermittent Hypoxia in Rats

Obstructive sleep apnea (OSA) can cause intermittent changes in blood oxygen saturation, resulting in the generation of many reactive oxygen species (ROS). To discover new antioxidants and clarify the endoplasmic reticulum (ER) stress involved in cardiac injury in OSA, we established a chronic intermittent hypoxia (CIH) rat model with a fraction of inspired O₂ (FiO₂) ranging from 21% to 9%, 20 times/h for 8 h/day, and the rats were treated with H₂-O₂ mixture (67% hydrogen and 33% oxygen) for 2 h/day for 35 days. Our results showed that H₂-O₂ mixture remarkably improved cardiac dysfunction and myocardial fibrosis. We found that H₂-O₂ mixture inhalation declined ER stress-induced apoptosis via three major response pathways: PERK-eIF2α-ATF4, IRE 1-XBP1, and ATF 6. Furthermore, we revealed that H₂-O₂ mixture blocked c-Jun N-terminal kinase- (JNK-) MAPK activation, increased the ratio of Bcl-2/Bax, and inhibited caspase 3 cleavage to protect against CIH-induced cardiac apoptosis. In addition, H₂-O₂ mixture considerably decreased ROS levels via upregulating superoxide dismutase (SOD) and glutathione (GSH) as well as downregulating NADPH oxidase (NOX 2) expression in the hearts of CIH rats. All the results demonstrated that H₂-O₂ mixture significantly reduced ER stress and apoptosis and that H₂ might be an efficient antioxidant against the oxidative stress injury induced by CIH.

Truncated chicken MDA5 enhances the immune response to inactivated NDV vaccine

Melanoma Differentiation-Associated protein 5 (MDA5) is a cytoplasmic sensor for viral invasion and plays an important role in regulation of the immune response against Newcastle disease virus (NDV) in chickens. MDA5 was used as an adjuvant to enhance the humoral immune response against influenza virus. In the current study, truncated chicken MDA5 [1-483 aa, chMDA5(483aa)] expressed by recombinant adenovirus was administered to specific-pathogen-free (SPF) chickens to improve the immune response induced by inactivated NDV vaccine. A total of 156 SPF chickens were divided into six groups, and after two rounds of immunization, the humoral immune response, cell-mediated immune (CMI) response and the protective efficacy of the vaccines against NDV challenge were evaluated. The results showed that co-administration of chMDA5(483aa) expressed by adenovirus increased the NDV-specific antibody response by 1.7 times and chickens received chMDA5(483aa) also gained a higher level of CMI response. Consistently, the protective efficacy of the inactivated NDV vaccine against virulent NDV (vNDV) challenge was improved by co-administrate with chMDA5(483aa), as indicated by the reduced morbidity and pathological lesions, lower levels of viral load in organs and reduced virus shedding. Our study demonstrated that chMDA5(433aa) expressed by adenovirus could enhance the immune efficacy of inactivated NDV vaccine in chickens and could be a potential adjuvant candidate in developing chicken NDV vaccines.

Lung Ischaemia-Reperfusion Injury: The Role of Reactive Oxygen Species

Lung ischaemia-reperfusion injury (LIRI) occurs in many lung diseases and during surgical procedures such as lung transplantation. The re-establishment of blood flow and oxygen delivery into the previously ischaemic lung exacerbates the ischaemic injury and leads to increased microvascular permeability and pulmonary vascular resistance as well as to vigorous activation of the immune response. These events initiate the irreversible damage of the lung with subsequent oedema formation that can result in systemic hypoxaemia and multi-organ failure. Alterations in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been suggested as crucial mediators of such responses during ischaemia-reperfusion in the lung. Among numerous potential sources of ROS/RNS within cells, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, xanthine oxidases, nitric oxide synthases and mitochondria have been investigated during LIRI. Against this background, we aim to review here the extensive literature about the ROS-mediated cellular signalling during LIRI, as well as the effectiveness of antioxidants as treatment option for LIRI.

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.

The Roles of Autophagy in Acute Lung Injury Induced by Myocardial Ischemia Reperfusion in Diabetic Rats

Patients with diabetes are vulnerable to myocardial ischemia reperfusion (IR) injury, which may also induce acute lung injury (ALI) due to overaccumulation of reactive oxygen species (ROS) and inflammation cytokine in circulation. Despite autophagy plays a significant role in diabetes and pulmonary IR injury, the role of autophagy in ALI secondary to myocardial IR in diabetes remains largely elusive. We aimed to investigate pulmonary autophagy status and its roles in oxidative stress and inflammation reaction in lung tissues from diabetic rats subjected to myocardial IR. Control or diabetic rats were either treated with or without autophagy inducer rapamycin (Rap) or autophagy inhibitor 3-methyladenine (3-MA) before myocardial IR, which was achieved by occluding the left anterior descending coronary artery for 30 min and followed by reperfusion for 120 min. Diabetic rats subjected to myocardial IR showed more serious ALI with higher lung injury score and WET/DRY ratio and lower PaO₂ as compared with control rats, accompanied with impaired autophagy indicated by reduced LC-3II/LC-3I ratio and Beclin-1 expression, decreased superoxide dismutase (SOD) activity, and increased 15-F2t-Isoprostane formation in lung tissues, as well as increased levels of leukocyte count and proinflammatory cytokines in BAL fluid. Improving autophagy with Rap significantly attenuated all these changes, but the autophagy inhibitor 3-MA exhibited adverse or opposite effects as Rap. In conclusion, diabetic lungs are more vulnerable to myocardial IR, which are involved in impaired autophagy. Improving autophagy could attenuate ALI induced by myocardial IR in diabetic rats, possibly through inhibiting inflammatory reaction and oxidative stress.

Lung inflation with hydrogen sulfide during the warm ischemia phase ameliorates injury in rat donor lungs via metabolic inhibition after cardiac death

BACKGROUND

Hydrogen sulfide attenuates lung ischemia-reperfusion injury when inhaled or administered intraperitoneally. This study investigated the effects of lung inflation with H₂S during the warm ischemia phase on lung grafts from rat donors after cardiac death.

METHODS

One hour after cardiac death, donor lungs were inflated in situ for 2 h with either O₂ or H₂S (O₂ or H₂S group) during the warm ischemia phase or were deflated as a control procedure (n = 8). After 3 h of cold preservation, lung transplantation was performed. During the warm ischemia phase, the metabolism and mitochondrial structures of donor lungs were analyzed. Arterial blood gas analysis was performed on the recipients. Protein expression in the graft of nuclear factor E2-related factor (Nrf)2 and nuclear factor kappa B (NF-κB) was analyzed by Western blotting, and static compliance, inflammation, oxidative stress, and cell apoptosis were assessed after 3 h of reperfusion.

RESULTS

When the O₂ and H₂S groups were compared with the control group, the mitochondrial structures were improved, and lactic acid levels, inflammation, oxidative stress, and cell apoptosis were significantly decreased; and glucose levels, as well as graft oxygenation and static compliance were increased. Simultaneously, the above indices showed further improvements, and the Nrf2 protein expression was significantly greater, and NF-κB protein expression was less in the H₂S group than the O₂ group.

CONCLUSION

Lung inflation with H₂S during the warm ischemia phase inhibited metabolism in donor lungs via mitochondrial protection, attenuated graft ischemic-reperfusion injury, and improved graft function through NF-κB-dependent anti-inflammatory and Nrf2-dependent antioxidative and antiapoptotic effects.

Hydrogen, a potential safeguard for graft-versus-host disease and graft ischemia-reperfusion injury?

Post-transplant complications such as graft-versus-host disease and graft ischemia-reperfusion injury are crucial challenges in transplantation. Hydrogen can act as a potential antioxidant, playing a preventive role against post-transplant complications in animal models of multiple organ transplantation. Herein, the authors review the current literature regarding the effects of hydrogen on graft ischemia-reperfusion injury and graft-versus-host disease. Existing data on the effects of hydrogen on ischemia-reperfusion injury related to organ transplantation are specifically reviewed and coupled with further suggestions for future work. The reviewed studies showed that hydrogen (inhaled or dissolved in saline) improved the outcomes of organ transplantation by decreasing oxidative stress and inflammation at both the transplanted organ and the systemic levels. In conclusion, a substantial body of experimental evidence suggests that hydrogen can significantly alleviate transplantation-related ischemia-reperfusion injury and have a therapeutic effect on graft-versus-host disease, mainly via inhibition of inflammatory cytokine secretion and reduction of oxidative stress through several underlying mechanisms. Further animal experiments and preliminary human clinical trials will lay the foundation for hydrogen use as a drug in the clinic.

Protection of donor lung inflation in the setting of cold ischemia against ischemia-reperfusion injury with carbon monoxide, hydrogen, or both in rats

AIMS

Lung ischemia-reperfusion injury (IRI) may be attenuated through carbon monoxide (CO)'s anti-inflammatory effect or hydrogen (H2)'s anti-oxidant effect. In this study, the effects of lung inflation with CO, H2, or both during the cold ischemia phase on graft function were observed.

MATERIALS AND METHODS

Rat donor lungs, inflated with 40% oxygen (control group), 500ppm CO (CO group), 3% H2 (H2 group) or 500ppm CO+3% H2 (COH group), were kept at 4°C for 180min. After transplantation, the recipients' artery blood gas and pressure-volume (P-V) curves were analyzed. The inflammatory response, oxidative stress and apoptosis in the recipients were assessed at 180min after reperfusion.

KEY FINDINGS

Oxygenation in the CO and H2 groups were improved compared with the control group. The CO and H2 groups also exhibited significantly improved P-V curves, reduced lung injury, and decreased inflammatory response, malonaldehyde content, and cell apoptosis in the grafts. Furthermore, the COH group experienced enhanced improvements in oxygenation, P-V curves, inflammatory response, lipid peroxidation, and graft apoptosis compared to the CO and H2 groups.

SIGNIFICANCE

Lung inflation with CO or H2 protected against IRI via anti-inflammatory, anti-oxidant and anti-apoptotic mechanisms in a model of lung transplantation in rats, which was enhanced by combined treatment with CO and H2.

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.