Hydrogen regulates mitochondrial quality to protect glial cells and alleviates sepsis-associated encephalopathy by Nrf2/YY1 complex promoting HO-1 expression

Molecular Hydrogen Therapy: Mechanisms, Delivery Methods, Preventive, and Therapeutic Application

Molecular hydrogen (H2), recognized as the smallest gas molecule, is capable of permeating cellular membranes and diffusing throughout the body. Due to its high bioavailability, H2 is considered a therapeutic gas for the treatment of various diseases. The therapeutic efficacy of hydrogen is contingent upon factors such as the administration method, duration of contact with diseased tissue, and concentration at targeted sites. H2 can be administered exogenously and is also produced endogenously within the intestinal tract. A comprehensive understanding of its delivery mechanisms and modes of action is crucial for advancing hydrogen medicine. This review highlights H₂'s mechanisms of action, summarizes its administration methods, and explores advancements in treating intestinal diseases (e.g., inflammatory bowel disease, intestinal ischemia-reperfusion, colorectal cancer). Additionally, its applications in managing other diseases are discussed. Finally, the challenges associated with its clinical application and potential solutions are explored. We propose that current delivery challenges faced by H2 can be effectively addressed through the use of nanoplatforms; furthermore, interactions between hydrogen and gut microbiota may provide insights into its mechanisms for treating intestinal diseases. Future research should explore the synergistic effects of H2 in conjunction with conventional therapies and develop personalized treatment plans to achieve precision medicine.

Ginsenoside Rh2 Alleviate Sepsis-related Encephalopathy via Up-regulating Nrf2/HO-1 Pathway and Apoptosis Inhibition

Sepsis patients are highly prone to sepsis-associated encephalopathy (SAE) complications, resulting in a high mortality rate. Recently, there has been no specific treatment for long-term improvement of cerebral function. Ginsenoside Rh2 is a form of steroidal saponins isolated from plant ginseng and has been shown to possess anti-inflammatory as well as neuroprotective characteristics; yet, the effect of ginsenoside Rh2 on SAE treatment is obscure. Accordingly, we proposed to investigate the effect of ginsenoside Rh2 in alleviating SAE damage. We established and utilized the SAE mouse model to determine the effect of Rh2 treatment on alleviating SAE. We determined the expression levels of Heme oxygenase-1(HO-1) and Nuclear factor erythroid 2-related factor 2 (Nrf2) as well as measured neural apoptosis by flow cytometry. Also, we quantified the levels of caspase-3, malondialdehyde (MDA), GSH-Px superoxide dismutase (SOD) and evaluated the animals' neural reflex function. First, used Rh2 to treat microglia BV2 and mouse neuron MN-c whether LPS exist or not, and then measured expression level of Iba-1, apoptotic rate, and ROS content applying flow cytometry. Also, we quantified the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). In comparison with the Sham group, the SAE model exhibited an elevated MDA content, caspase-3 activity, and cell apoptosis. On the other hand, the GSH-Px activity and SOD level were decreased along with a decreased neural reflex score. Our investigation concluded that Rh2 treatment significantly alleviated SAE damage and inhibited LPS-induced response via up-regulation of the Nrf2/HO-1 pathway to promote anti-oxidative stress capacity and inhibit neural cell apoptosis.

High Concentration Hydrogen Protects Sepsis-Associated Encephalopathy by Enhancing Pink1/Parkin-Mediated Mitophagy and Inhibiting cGAS-STING-IRF3 Pathway

BACKGROUND

Sepsis-associated encephalopathy (SAE) leads to increased mortality. Hydrogen (H2) has been proven to be effective in protecting against SAE. This study aimed to investigate the protective mechanism of a high concentration of H2 (HCH) (67%) against SAE.

METHODS

A mouse sepsis model was established via cecal ligation and puncture (CLP). 67% H2 was inhaled for 1 h at 1 h and 6 h after the operation. First, mice were randomly divided into 5 groups: Sham, CLP, CLP + CQ (a mitophagy inhibitor), CLP + H2, and CLP + H2 + CQ. Seven-day survival, cognitive function, and hippocampal damage were assessed. Then, mice were randomly divided into four groups: Sham, CLP, CLP + UA (a mitophagy agonist), and CLP + H2. Seven-day survival was recorded, cognitive function was assessed via Y-maze and Morris water maze tests, and hippocampal damage was evaluated via Nissl staining. Phosphorylated tau, inflammatory factors, ATP, and antioxidant enzyme levels and mitochondrial membrane potential (MMP) were detected. Mitochondria were observed via transmission electron microscopy. The protein levels of the PINK1/Parkin pathway and STING-TBK-IRF3 pathway were detected via western blotting.

RESULTS

HCH inhalation improves 7-day survival and cognitive function in septic mice and reduces brain tissue damage, proinflammatory cytokine levels, and phosphorylated tau levels. These effects were reversed by a mitophagy inhibitor. HCH significantly improves mitochondrial function, enhances PINK1/Parkin-mediated mitophagy, and reduces the activity of the STING-TBK-IRF3 pathway in brain tissue.

CONCLUSIONS

HCH inhalation effectively improved the survival rate of septic mice, alleviated SAE, and reduced tau phosphorylation. The mechanism may involve HCH enhancing PINK1/Parkin-mediated mitophagy, which inhibits the activity of the cGAS-STING-IRF3 pathway, thereby reducing neuroinflammation.

Hydrogen restores central tryptophan and metabolite levels and maintains mitochondrial homeostasis to protect rats from chronic mild unpredictable stress damage

BACKGROUND AND PURPOSE

The field of hydrogen medicine has garnered extensive attention since Professor Ohsawa established that low concentrations of hydrogen (2%-4%) exert antioxidant effects. The present study aimed to evaluate the therapeutic effect of molecular hydrogen in a CUMS rat model.

METHODS

A total of 40 SD rats were randomly divided into a control group, a model group, a hydrogen group, and a positive drug group. Four weeks post-modeling, hydrogen inhalation and other treatments were administered. Behavioral, biochemical, and immunohistochemical evaluations were performed after treatment.

RESULTS

Hydrogen inhalation alleviated depressive behavior and hippocampal neuronal damage in CUMS rats, as well as restored the levels of neurotransmitters, inflammatory factors, and oxidative stress. Moreover, it maintained mitochondrial homeostasis and up-regulated the expression of PGC-1α, PINK1, and Parkin.

CONCLUSIONS

The results collectively indicated that hydrogen significantly attenuated CUMS-induced depressive-like behavior and monoamine neurotransmitter deficiency, as well as protected the brain from oxidative stress and inflammatory damage and effectively preserved mitochondrial homeostasis.

High-concentration hydrogen inhalation mitigates sepsis-associated encephalopathy in mice by improving mitochondrial dynamics

BACKGROUND

Sepsis-associated encephalopathy (SAE) is a neuronal injury with poor prognosis. Mitochondrial dysfunction is critical in SAE development, and hydrogen gas (H2) has a protective effect on septic mice. This study aimed to investigate the effect of high concentration (67%) of H2 on SAE and whether it is related to mitochondrial biogenesis and mitochondrial dynamics.

METHODS

A mouse sepsis model was induced by cecal ligation and puncture. The mice inhalated 67% H2 for 1 h at 1 and 6 h post-surgery, respectively. The 7-day survival rate was recorded. Cognitive function was assessed using the Y-maze test and Morris water maze test. Serum inflammatory factors, antioxidant enzymes, as well as mitochondrial function indexes including mitochondrial membrane potential (MMP) and ATP in the hippocampal tissue were evaluated 24 h after surgery. Mitochondrial dynamic proteins (DRP1 and MFN2) and biosynthetic proteins (PGC-1α, NRF2, and TFAM) in the hippocampal tissue were detected. Moreover, the morphology of mitochondria was observed by transmission electron microscopy.

RESULTS

Inhalation of 67% H2 improved the 7-day survival rates and recognition memory function of septic mice, alleviated brain antioxidant enzyme activity (SOD and CAT), and reduced serum proinflammatory cytokine levels. H2 inhalation also enhanced the expression of MFN2 and mitochondrial biogenesis-related factors (PGC-1α, NRF2, and TFAM) and decreased the expression of fission protein (DRP1), leading to improvement in mitochondrial function, as evidenced by MMP and ATP levels.

CONCLUSIONS

Inhalation of high concentration (67%) of H2 in septic mice improved the survival rate and reduced neuronal injury. Its mechanism might be mediated by enhancing mitochondrial biogenesis and mitochondrial dynamics.

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.

Mitochondria: one of the vital hubs for molecular hydrogen's biological functions

As a novel antioxidant, a growing body of studies has documented the diverse biological effects of molecular hydrogen (H2) in a wide range of organisms, spanning animals, plants, and microorganisms. Although several possible mechanisms have been proposed, they cannot fully explain the extensive biological effects of H2. Mitochondria, known for ATP production, also play crucial roles in diverse cellular functions, including Ca2+ signaling, regulation of reactive oxygen species (ROS) generation, apoptosis, proliferation, and lipid transport, while their dysfunction is implicated in a broad spectrum of diseases, including cardiovascular disorders, neurodegenerative conditions, metabolic disorders, and cancer. This review aims to 1) summarize the experimental evidence on the impact of H2 on mitochondrial function; 2) provide an overview of the mitochondrial pathways underlying the biological effects of H2, and 3) discuss H2 metabolism in eukaryotic organisms and its relationship with mitochondria. Moreover, based on previous findings, this review proposes that H2 may regulate mitochondrial quality control through diverse pathways in response to varying degrees of mitochondrial damage. By combining the existing research evidence with an evolutionary perspective, this review emphasizes the potential hydrogenase activity in mitochondria of higher plants and animals. Finally, this review also addresses potential issues in the current mechanistic study and offers insights into future research directions, aiming to provide a reference for future studies on the mechanisms underlying the action of H2.

Effects of the PI3K/Akt/HO-1 pathway on autophagy in a sepsis-induced acute lung injury mouse model

Sepsis-induced lung injury is an acute hypoxic respiratory insufficiency caused by systemic infectious factors that results in alveolar epithelial cell and capillary endothelial cell injury, diffuse pulmonary interstitial edema, and alveolar edema. Heme oxygenase (HO)-1 is usually associated with inflammation and has anti-inflammatory effects. Autophagy is a degradation pathway that eliminates cellular metabolic waste and plays an important protective role during stress. The phosphatidylinositol 3-kinase/ protein kinase B (PI3K/Akt) signaling pathway plays a key role in mediating cellular responses to inflammatory reactions. Therefore, we hypothesized that HO-1 is associated with autophagy and regulated by the PI3K/Akt signaling pathway in mice with sepsis-induced lung injury. Sepsis-induced lung injury was induced in mice using cecal ligation and puncture (CLP). Hemin or Sn-protoporphyrin IX (SnPP) was administered via intraperitoneal injection before surgery. Survival rates were observed during days 1-7 after the surgery; lung histology was discerned 24 h after the surgery; pro-inflammatory and anti-inflammatory factors in plasma and lung tissue were measured using enzyme-linked immunosorbent assay (ELISA); HO-1, Beclin-1, microtubule-associated protein 1 light chain 3B (LC3B)-II, p62 and lysosome associated membrane protein (LAMP)2 protein expression levels were measured 24 h after the surgery; HO-1 and LC3B-II protein expression levels were observed using immunofluorescence 24 h after the surgery; and autophagosomes were detected using electron microscopy 24 h after the surgery. Furthermore, when PI3K inhibitors LY294002, PI3K activators Recilisib and hemin were administered before the surgery, Akt, p-Akt, HO-1, and LC3-II levels were measured 24 h post-surgery. We found that HO-1 overexpression increased the survival rate and inhibited sepsis-induced lung injury. HO-1 overexpression attenuated the levels of proinflammatory cytokines (TNF-α, IL-1β) and increased the anti-inflammatory cytokine (IL-10, HO-1) overexpression. Moreover, HO-1 overexpression was also associated with increased expression of Beclin-1, LC3B-II and LAMP2 protein expression; decreased p62 protein expression; and significantly increased autophagosome formation. The results for HO-1-downregulated mice contrasted with those mentioned above. LY294002 inhibited p-Akt/Akt, HO-1, and LC3B-II protein expression; and hemin reversed the inhibitory effect of LY294002. The protective effect of HO-1 was involved in the mediation of autophagy, which may be regulated by the PI3K/Akt signaling pathway during sepsis-induced lung injury in mice.

Role of SIRT1 in sepsis-induced encephalopathy: Molecular targets for future therapies

Sepsis induces neuroinflammation, BBB disruption, cerebral hypoxia, neuronal mitochondrial dysfunction, and cell death causing sepsis-associated encephalopathy (SAE). These pathological consequences lead to short- and long-term neurobehavioural deficits. Till now there is no specific treatment that directly improves SAE and its associated behavioural impairments. In this review, we discuss the underlying mechanisms of sepsis-induced brain injury with a focus on the latest progress regarding neuroprotective effects of SIRT1 (silent mating type information regulation-2 homologue-1). SIRT1 is an NAD+ -dependent class III protein deacetylase. It is able to modulate multiple downstream signals (including NF-κB, HMGB, AMPK, PGC1α and FoxO), which are involved in the development of SAE by its deacetylation activity. There are multiple recent studies showing the neuroprotective effects of SIRT1 in neuroinflammation related diseases. The proposed neuroprotective action of SIRT1 is meant to bring a promising therapeutic strategy for managing SAE and ameliorating its related behavioural deficits.

YY1/miR-140-5p/Jagged1/Notch axis mediates cartilage progenitor/stem cells fate reprogramming in knee osteoarthritis

Osteoarthritis is a multifactorial disease characterized by cartilage degeneration, while cartilage progenitor/stem cells (CPCs) are responsible for endogenous cartilage repair. However, the relevant regulatory mechanisms of CPCs fate reprogramming in OA are rarely reported. Recently, we observed fate disorders in OA CPCs and found that microRNA-140-5p (miR-140-5p) protects CPCs from fate changes in OA. This study further mechanistically investigated the upstream regulator and downstream effectors of miR-140-5p in OA CPCs fate reprogramming. As a result, luciferase reporter assay and validation assays revealed that miR-140-5p targets Jagged1 and inhibits Notch signaling in human CPCs, and the loss-/gain-of-function experiments and rescue assays discovered that miR-140-5p improves OA CPCs fate, but this effect can be counteracted by Jagged1. Moreover, increased transcription factor Ying Yang 1 (YY1) was associated with OA progression, and YY1 could disturb CPCs fate via transcriptionally repressing miR-140-5p and enhancing the Jagged1/Notch signaling. Finally, the relevant changes and mechanisms of YY1, miR-140-5p, and Jagged1/Notch signaling in OA CPCs fate reprogramming were validated in rats. Conclusively, this study identified a novel YY1/miR-140-5p/Jagged1/Notch signaling axis that mediates OA CPCs fate reprogramming, wherein YY1 and Jagged1/Notch signaling exhibits an OA-stimulative role, and miR-140-5p plays an OA-protective effect, providing attractive targets for OA therapeutics.