Ganglioside GM1 protects against high altitude cerebral edema in rats by suppressing the oxidative stress and inflammatory response via the PI3K/AKT-Nrf2 pathway

Superoxide dismutase 1-modified dental pulp stem cells alleviate high-altitude pulmonary edema by inhibiting oxidative stress through the Nrf2/HO-1 pathway

High-altitude pulmonary edema (HAPE) is a deadly form of altitude sickness, and there is no effective treatment for HAPE. Dental pulp stem cells (DPSCs) are a type of mesenchymal stem cell isolated from dental pulp tissues and possess various functions, such as anti-inflammatory and anti-oxidative stress. DPSCs have been used to treat a variety of diseases, but there are no studies on treating HAPE. In this study, Sprague-Dawley rats were exposed to acute low-pressure hypoxia to establish the HAPE model, and SOD1-modified DPSCs (DPSCsHiSOD1) were administered through the tail vein. Pulmonary arterial pressure, lung water content (LWC), total lung protein content of bronchoalveolar lavage fluid (BALF) and lung homogenates, oxidative stress, and inflammatory indicators were detected to evaluate the effects of DPSCsHiSOD1 on HAPE. Rat type II alveolar epithelial cells (RLE-6TN) were used to investigate the effects and mechanism of DPSCsHiSOD1 on hypoxia injury. We found that DPSCs could treat HAPE, and the effect was better than that of dexamethasone treatment. SOD1 modification could enhance the function of DPSCs in improving the structure of lung tissue, decreasing pulmonary arterial pressure and LWC, and reducing the total lung protein content of BALF and lung homogenates, through anti-oxidative stress and anti-inflammatory effects. Furthermore, we found that DPSCsHiSOD1 could protect RLE-6TN from hypoxic injury by reducing the accumulation of reactive oxygen species (ROS) and activating the Nrf2/HO-1 pathway. Our findings confirm that SOD1 modification could enhance the anti-oxidative stress ability of DPSCs through the Nrf2/HO-1 signalling pathway. DPSCs, especially DPSCsHiSOD1, could be a potential treatment for HAPE. Schematic diagram of the antioxidant stress mechanism of DPSCs in the treatment of high-altitude pulmonary edema. DPSCs can alleviate oxidative stress by releasing superoxide dismutase 1, thereby reducing ROS production and activating the Nrf2/HO-1 signalling pathway to ameliorate lung cell injury in HAPE.

GM1 Ameliorates Neuronal Injury in Rats after Cerebral Ischemia and Reperfusion: Potential Contribution of Effects on SPTBN1-mediated Signaling

Monosialoganglioside GM1 (GM1) has long been used as a therapeutic agent for neurological diseases in the clinical treatment of ischemic stroke. However, the mechanism underlying the neuroprotective function of GM1 is still obscure until now. In this study, we investigated the effects of GM1 in ischemia and reperfusion (I/R) brain injury models. Middle cerebral artery occlusion and reperfusion (MCAO/R) rats were treated with GM1 (60 mg·kg-1·d-1, tail vein injection) for 2 weeks. The results showed that GM1 substantially attenuated the MCAO/R-induced neurological dysfunction and inhibited the inflammatory responses and cell apoptosis in ischemic parietal cortex. We further revealed that GM1 inhibited the activation of NFκB/MAPK signaling pathway induced by MCAO/R injury. To explore its underlying mechanism of the neuroprotective effect, transcriptome sequencing was introduced to screen the differentially expressed genes (DEGs). By function enrichment and PPI network analyses, Sptbn1 was identified as a node gene in the network regulated by GM1 treatment. In the MCAO/R model of rats and oxygen-glucose deprivation and reperfusion (OGD/R) model of primary culture of rat cortical neurons, we first found that SPTBN1 was involved in the attenuation of I/R induced neuronal injury after GM1 administration. In SPTBN1-knockdown SH-SY5Y cells, the treatment with GM1 (20 μM) significantly increased SPTBN1 level. Moreover, OGD/R decreased SPTBN1 level in SPTBN1-overexpressed SH-SY5Y cells. These results indicated that GM1 might achieve its potent neuroprotective effects by regulating inflammatory response, cell apoptosis, and cytomembrane and cytoskeleton signals through SPTBN1. Therefore, SPTBN1 may be a potential target for the treatment of ischemic stroke.

Rapid altitude displacement induce zebrafish appearing acute high altitude illness symptoms

Rapid ascent to high-altitude areas above 2500 m often leads to acute high altitude illness (AHAI), posing significant health risks. Current models for AHAI research are limited in their ability to accurately simulate the high-altitude environment for drug screening. Addressing this gap, a novel static self-assembled water vacuum transparent chamber was developed to induce AHAI in zebrafish. This study identified 6000 m for 2 h as the optimal condition for AHAI induction in zebrafish. Under these conditions, notable behavioral changes including slow movement, abnormal exploration behavior and static behavior in the Novel tank test. Furthermore, this model demonstrated changes in oxidative stress-related markers included increased levels of malondialdehyde, decreased levels of glutathione, decreased activities of superoxide dismutase and catalase, and increased levels of inflammatory markers IL-6, IL-1β and TNF-α, and inflammatory cell infiltration and mild edema in the gill tissue, mirroring the clinical pathophysiology observed in AHAI patients. This innovative zebrafish model not only offers a more accurate representation of the high-altitude environment but also provides a high-throughput platform for AHAI drug discovery and pathogenesis research.

GM1 ganglioside protects against LPS-induced neuroinflammatory and oxidative responses by inhibiting the activation of Akt, TAK1 and NADPH oxidase in MG6 microglial cells

GM1 is a major brain ganglioside that exerts neurotrophic, neuroprotective and antineuroinflammatory effects. The aim of this study was to obtain insights into the antineuroinflammatory mechanisms of exogenous GM1 in lipopolysaccharide (LPS)-stimulated MG6 mouse transformed microglial cell line. First, we found that GM1 prevented the LPS-induced transformation of microglia into an amoeboid-like shape. GM1 treatment inhibited LPS-induced expression of inducible nitric oxide synthase, cyclooxygenase-2 (COX-2), and proinflammatory cytokines such as TNF-α, IL-1β and IL-6 in MG6 cells. In LPS-treated mice, GM1 also reduced striatal microglia activation and attenuated COX-2 expression. Subsequent mechanistic studies showed that GM1 suppressed LPS-induced nuclear translocation of nuclear factor κB (NF-κB) and activator protein-1 (AP-1), two critical transcription factors responsible for the production of proinflammatory mediators. GM1 exhibited antineuroinflammatory properties by suppressing Akt/NF-κB signaling and the activation of mitogen-activated protein kinases (MAPKs), including p38 MAPK, extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK). Furthermore, GM1 suppressed LPS-induced activation of transforming growth factor-β-activated kinase 1 (TAK1) and NADPH oxidase 2 (NOX2), upstream regulators of the IκBα/NF-κB and MAPK/AP-1 signaling pathways. GM1 also inhibited NOX-mediated reactive oxygen species (ROS) production and protected against LPS-induced MG6 cell death, suggesting an antioxidant role of GM1. In conclusion, GM1 exerts both antineuroinflammatory and antioxidative effects by inhibiting Akt, TAK1 and NOX2 activation.

Resveratrol Improves Cognitive Function in Post-stroke Depression Rats by Repressing Inflammatory Reactions and Oxidative Stress via the Nrf2/HO-1 Pathway

Post-stroke depression (PSD) is a prevalent mental health issue, and resveratrol (RES) has been implicated in its management. This study aimed to elucidate the impact of RES on PSD. A PSD rat model was established through middle cerebral artery occlusion and chronic unpredictable mild stress. Rats received RES via gavage, and depressive behaviors were evaluated through various measures. Cerebral infarction areas and brain tissue pathology were assessed using TTC and H&E staining. Levels of inflammatory factors (TNF-α/IL-1β/IL-6/IL-10), neurotransmitters (ACH/DA/5-HT/BDNF), and oxidative stress-related indicators (SOD/GSH-Px/MDA), along with the total Nrf2/C-Nrf2/N-Nrf2/HO-1 proteins, were analyzed. The role of the Nrf2/HO-1 pathway was investigated by co-treating rats with RES and either an Nrf2 pathway specific inhibitor (ML385) or activator (dimethyl fumarate). PSD rats exhibited depressive behaviors, disrupted neurotransmitter levels, and oxidative stress markers. RES treatment effectively alleviated these symptoms and activated the Nrf2/HO-1 pathway in PSD rat brain tissues. Co-administration of ML385 attenuated the beneficial effects of RES in PSD rats. Altogether, RES mitigates depressive behaviors, improves cognitive dysfunction, and reduces oxidative stress and inflammatory response in PSD rats. These effects are mediated through the activation of the Nrf2/HO-1 pathway, suggesting RES as a potential therapeutic agent for PSD-related cognitive impairment.

Impact of NQO1 dysregulation in CNS disorders

NAD(P)H Quinone Dehydrogenase 1 (NQO1) plays a pivotal role in the regulation of neuronal function and synaptic plasticity, cellular adaptation to oxidative stress, neuroinflammatory and degenerative processes, and tumorigenesis in the central nervous system (CNS). Impairment of the NQO1 activity in the CNS can result in abnormal neurotransmitter release and clearance, increased oxidative stress, and aggravated cellular injury/death. Furthermore, it can cause disturbances in neural circuit function and synaptic neurotransmission. The abnormalities of NQO1 enzyme activity have been linked to the pathophysiological mechanisms of multiple neurological disorders, including Parkinson's disease, Alzheimer's disease, epilepsy, multiple sclerosis, cerebrovascular disease, traumatic brain injury, and brain malignancy. NQO1 contributes to various dimensions of tumorigenesis and treatment response in various brain tumors. The precise mechanisms through which abnormalities in NQO1 function contribute to these neurological disorders continue to be a subject of ongoing research. Building upon the existing knowledge, the present study reviews current investigations describing the role of NQO1 dysregulations in various neurological disorders. This study emphasizes the potential of NQO1 as a biomarker in diagnostic and prognostic approaches, as well as its suitability as a target for drug development strategies in neurological disorders.

High altitude hypoxia and oxidative stress: The new hope brought by free radical scavengers

Various strategies can be employed to prevent and manage altitude illnesses, including habituation, oxygenation, nutritional support, and medication. Nevertheless, the utilization of drugs for the prevention and treatment of hypoxia is accompanied by certain adverse effects. Consequently, the quest for medications that exhibit minimal side effects while demonstrating high efficacy remains a prominent area of research. In this context, it is noteworthy that free radical scavengers exhibit remarkable anti-hypoxia activity. These scavengers effectively eliminate excessive free radicals and mitigate the production of reactive oxygen species (ROS), thereby safeguarding the body against oxidative damage induced by plateau hypoxia. In this review, we aim to elucidate the pathogenesis of plateau diseases that are triggered by hypoxia-induced oxidative stress at high altitudes. Additionally, we present a range of free radical scavengers as potential therapeutic and preventive approaches to mitigate the occurrence of common diseases associated with hypoxia at high altitudes.

Mechanism of baixiangdan capsules on anti-neuroinflammation: combining dry and wet experiments

Neuroinflammation plays an important role in the pathogenesis of neurological disorders, and despite intensive research, treatment of neuroinflammation remains limited. BaiXiangDan capsule (BXD) is widely used in clinical practice. However, systematic studies on the direct role and mechanisms of BXD in neuroinflammation are still lacking. We systematically evaluated the potential pharmacological mechanisms of BXD on neuroinflammation using network pharmacological analysis combined with experimental validation. Multiple databases are used to mine potential targets for bioactive ingredients, drug targets and neuroinflammation. GO and KEGG pathway analysis was also performed. Interactions between active ingredients and pivotal targets were confirmed by molecular docking. An experimental model of neuroinflammation was used to evaluate possible therapeutic mechanisms for BXD. Network pharmacological analysis revealed that Chrysoeriol, Kaempferol and Luteolin in BXD exerted their anti-neuroinflammatory effects mainly by acting on targets such as NCOA2, PIK3CA and PTGS2. Molecular docking results showed that their average affinity was less than -5 kcal/mol, with an average affinity of -8.286 kcal/mol. Pathways in cancer was found to be a potentially important pathway, with involvement of PI3K/AKT signaling pathways. In addition, in vivo experiments showed that BXD treatment ameliorated neural damage and reduced neuronal cell death. Western blotting, RT-qPCR and ELISA analysis showed that BXD inhibited not only the expression of IL-1β, TNF-α and NO, but also NF-κB, MMP9 and PI3K/AKT signaling pathways. This study applied network pharmacology and in vivo experiments to explore the possible mechanisms of BXD against neuroinflammation, providing insight into the treatment of neuroinflammation.

Progress in the Treatment of High Altitude Cerebral Edema: Targeting REDOX Homeostasis

With the increasing of altitude activities from low-altitude people, the study of high altitude cerebral edema (HACE) has been revived. HACE is a severe acute mountain sickness associated with exposure to hypobaric hypoxia at high altitude, often characterized by disturbance of consciousness and ataxia. As for the pathogenesis of HACE, previous studies suggested that it might be related to the disorder of cerebral blood flow, the destruction of blood-brain barrier and the injury of brain parenchyma cells caused by inflammatory factors. In recent years, studies have confirmed that the imbalance of REDOX homeostasis is also involved in the pathogenesis of HACE, which mainly leads to abnormal activation of microglia and destruction of tight junction of vascular endothelial cells through the excessive production of mitochondrial-related reactive oxygen species. Therefore, this review summarizes the role of REDOX homeostasis and the potential of the treatment of REDOX homeostasis in HACE, which is of great significance to expand the understanding of the pathogenesis of HACE. Moreover, it will also be helpful to further study the possible therapy of HACE related to the key link of REDOX homeostasis.

Ganglioside GM1 and the Central Nervous System

GM1 is one of the major glycosphingolipids (GSLs) on the cell surface in the central nervous system (CNS). Its expression level, distribution pattern, and lipid composition are dependent upon cell and tissue type, developmental stage, and disease state, which suggests a potentially broad spectrum of functions of GM1 in various neurological and neuropathological processes. The major focus of this review is the roles that GM1 plays in the development and activities of brains, such as cell differentiation, neuritogenesis, neuroregeneration, signal transducing, memory, and cognition, as well as the molecular basis and mechanisms for these functions. Overall, GM1 is protective for the CNS. Additionally, this review has also examined the relationships between GM1 and neurological disorders, such as Alzheimer's disease, Parkinson's disease, GM1 gangliosidosis, Huntington's disease, epilepsy and seizure, amyotrophic lateral sclerosis, depression, alcohol dependence, etc., and the functional roles and therapeutic applications of GM1 in these disorders. Finally, current obstacles that hinder more in-depth investigations and understanding of GM1 and the future directions in this field are discussed.

GM1 Ganglioside as a Disease-Modifying Therapeutic for Parkinson's Disease: A Multi-Functional Glycosphingolipid That Targets Multiple Parkinson's Disease-Relevant Pathogenic Mechanisms

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting millions of patients worldwide. Many therapeutics are available for treating PD symptoms but there is no disease-modifying therapeutic that has been unequivocally shown to slow or stop the progression of the disease. There are several factors contributing to the failure of many putative disease-modifying agents in clinical trials and these include the choice of patients and clinical trial designs for disease modification trials. Perhaps more important, however, is the choice of therapeutic, which for the most part, has not taken into account the multiple and complex pathogenic mechanisms and processes involved in PD. This paper discusses some of the factors contributing to the lack of success in PD disease-modification trials, which have mostly investigated therapeutics with a singular mechanism of action directed at one of the many PD pathogenic processes, and suggests that an alternative strategy for success may be to employ multi-functional therapeutics that target multiple PD-relevant pathogenic mechanisms. Evidence is presented that the multi-functional glycosphingolipid GM1 ganglioside may be just such a therapeutic.

Curcumin alleviates ketamine-induced oxidative stress and apoptosis via Nrf2 signaling pathway in rats' cerebral cortex and hippocampus

AIMS

To investigate curcumin's protective effect on nerve damage caused by ketamine anesthesia via the Nrf2 signaling pathway. Rats and PC12 cells were used in this experiment to investigate the mechanism of nerve injury caused by ketamine anesthesia. Furthermore, our findings suggest that curcumin may affect oxidative stress and apoptosis by targeting the Nrf2 pathway, thereby alleviating the nerve injury caused by ketamine.

METHODS

The rat cerebral cortex and hippocampus were stained with Nissl and immunohistochemistry to determine the number of neurons and the expression of Caspase-3, Bcl-2, and Bax. CCK-8 assay was used to determine the optimal concentration of ketamine, curcumin, and H₂ O₂ in PC12 cells. Flow cytometry was used to detect changes in reactive oxygen species and the rate of apoptosis in each group. To determine whether Nrf2 entered the nucleus, immunofluorescence was used. Both tissues and cells were subjected to RT-PCR and Western blotting detection at the same time. The levels of oxidative stress were determined using a malondialdehyde (MDA) and superoxide dismutase (SOD) assay kit.

RESULTS

Ketamine reduced the number of neurons in the cortex and hippocampus of rats. The proteins Bax and Caspase-3 were upregulated, while Bcl-2 was down-regulated in the cortex and hippocampus. The viability of PC12 cells has decreased. MDA content increased while SOD activity decreased in cortex, hippocampus, and PC12 cells. Ketamine had an effect on the expression of some genes in the Nrf2 signaling pathway as well as apoptosis. Curcumin pretreatment may be able to prevent ketamine-induced damage.

CONCLUSIONS

The oxidative stress and apoptosis caused by ketamine during growth of the cerebral cortex, hippocampus, and PC12 cells may be decreased by curcumin's activation of the Nrf2 signaling pathway. Our research provides a potential strategy for the secure administration of anesthetics in medical settings.

Molecular Mechanisms of High-Altitude Acclimatization

High-altitude illnesses (HAIs) result from acute exposure to high altitude/hypoxia. Numerous molecular mechanisms affect appropriate acclimatization to hypobaric and/or normobaric hypoxia and curtail the development of HAIs. The understanding of these mechanisms is essential to optimize hypoxic acclimatization for efficient prophylaxis and treatment of HAIs. This review aims to link outcomes of molecular mechanisms to either adverse effects of acute high-altitude/hypoxia exposure or the developing tolerance with acclimatization. After summarizing systemic physiological responses to acute high-altitude exposure, the associated acclimatization, and the epidemiology and pathophysiology of various HAIs, the article focuses on molecular adjustments and maladjustments during acute exposure and acclimatization to high altitude/hypoxia. Pivotal modifying mechanisms include molecular responses orchestrated by transcription factors, most notably hypoxia inducible factors, and reciprocal effects on mitochondrial functions and REDOX homeostasis. In addition, discussed are genetic factors and the resultant proteomic profiles determining these hypoxia-modifying mechanisms culminating in successful high-altitude acclimatization. Lastly, the article discusses practical considerations related to the molecular aspects of acclimatization and altitude training strategies.

Caveolin-1 accelerates hypoxia-induced endothelial dysfunction in high-altitude cerebral edema

Background

High-altitude cerebral edema (HACE) is a serious and potentially fatal brain injury that is caused by acute hypobaric hypoxia (HH) exposure. Vasogenic edema is the main pathological factor of this condition. Hypoxia-induced disruptions of tight junctions in the endothelium trigger blood‒brain barrier (BBB) damage and induce vasogenic edema. Nuclear respiratory factor 1 (NRF1) acts as a major regulator of hypoxia-induced endothelial cell injury, and caveolin-1 (CAV-1) is upregulated as its downstream gene in hypoxic endothelial cells. This study aimed to investigate whether CAV-1 is involved in HACE progression and the underlying mechanism.

Methods

C57BL/6 mice were exposed to HH (7600 m above sea level) for 24 h, and BBB injury was assessed by brain water content, Evans blue staining and FITC-dextran leakage. Immunofluorescence, transmission electron microscope, transendothelial electrical resistance (TEER), transcytosis assays, and western blotting were performed to confirm the role and underlying mechanism of CAV-1 in the disruption of tight junctions and BBB permeability. Mice or bEnd.3 cells were pretreated with MβCD, a specific blocker of CAV-1, and the effect of CAV-1 on claudin-5 internalization under hypoxic conditions was detected by immunofluorescence, western blotting, and TEER. The expression of NRF1 was knocked down, and the regulation of CAV-1 by NRF1 under hypoxic conditions was examined by qPCR, western blotting, and immunofluorescence.

Results

The BBB was severely damaged and was accompanied by a significant loss of vascular tight junction proteins in HACE mice. CAV-1 was significantly upregulated in endothelial cells, and claudin-5 explicitly colocalized with CAV-1. During the in vitro experiments, hypoxia increased cell permeability, CAV-1 expression, and claudin-5 internalization and downregulated tight junction proteins. Simultaneously, hypoxia induced the upregulation of CAV-1 by activating NRF1. Blocking CAV-1-mediated intracellular transport improved the integrity of TJs in hypoxic endothelial cells and effectively inhibited the increase in BBB permeability and brain water content in HH animals.

Conclusions

Hypoxia upregulated CAV-1 transcription via the activation of NRF1 in endothelial cells, thus inducing the internalization and autophagic degradation of claudin-5. These effects lead to the destruction of the BBB and trigger HACE. Therefore, CAV-1 may be a potential therapeutic target for HACE.

Aberrant Ganglioside Functions to Underpin Dysregulated Myelination, Insulin Signalling, and Cytokine Expression: Is There a Link and a Room for Therapy?

Gangliosides are molecules widely present in the plasma membranes of mammalian cells, participating in a variety of processes, including protein organization, transmembrane signalling and cell adhesion. Gangliosides are abundant in the grey matter of the brain, where they are critically involved in postnatal neural development and function. The common precursor of the majority of brain gangliosides, GM3, is formed by the sialylation of lactosylceramide, and four derivatives of its a- and b-series, GM1, GD1a, GD1b and GT1b, constitute 95% of all the brain gangliosides. Impairments in ganglioside metabolism due to genetic abnormalities of GM-synthases are associated with severe neurological disorders. Apart from that, the latest genome-wide association and translational studies suggest a role of genes involved in brain ganglioside synthesis in less pervasive psychiatric disorders. Remarkably, the most recent animal studies showed that abnormal ganglioside functions result in dysregulated neuroinflammation, aberrant myelination and altered insulin receptor signalling. At the same time, these molecular features are well established as accompanying developmental psychiatric disorders such as attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD). This led us to hypothesize a role of deficient ganglioside function in developmental neuropsychiatric disorders and warrants further gene association clinical studies addressing this question. Here, we critically review the literature to discuss this hypothesis and focus on the recent studies on ST3GAL5-deficient mice. In addition, we elaborate on the therapeutic potential of various anti-inflammatory remedies for treatment of developmental neuropsychiatric conditions related to aberrant ganglioside functions.

The Neuroprotective Effect of GM-1 Ganglioside on the Amyloid-Beta-Induced Oxidative Stress in PC-12 Cells Mediated by Nrf-2/ARE Signaling Pathway

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-β (Aβ) plaques, tau tangles, neuroinflammation, oxidative stress, and progressive memory deficits. Aβ deposition could exacerbate oxidative damage and cellular apoptosis. GM-1 ganglioside (GM-1) has previously been reported to exhibit neuroprotective effects in rodents and patients with AD. However, the substantial impacts and mechanism of GM-1 on Aβ-induced oxidative stress remain elusive. The present study used PC-12 pheochromocytoma cells treated with Aβ_25-35 peptide to construct the AD model in vitro. Aβ_25-35 administration alone inhibited cell viability and facilitated cell apoptosis in the range doses of 10 μM to 30 μM. At the same time, GM-1 supplementation promoted cell proliferation and rescued cell apoptosis in a dose-dependent fashion ranging from 5 to 30 μM. In parallel, GM-1 treatment alleviated Aβ-induced oxidative stress by increasing the level of antioxidant enzymes and decreasing the content of malondialdehyde (MDA). The nuclear factor-E2-related factor 2 (Nrf2) is a crucial mediator of antioxidant response. We reported herein that GM-1 could activate Nrf-2 in the PC-12 cells co-treated with Aβ_25-35, following with the activated expression of antioxidant response elements (ARE)-mediated antioxidant and detoxifying genes. Consistently, knock-down of Nrf-2 via siRNA abolished the beneficial decrease of Aβ-induced oxidative stress by GM-1 treatment, indicating that GM-1-improved oxidative stress was regulated by the Nrf-2 signaling pathway. Collectively, GM-1 could alleviate Aβ_25-35-induced oxidative damage mediated through the Nrf-2/ARE signaling pathway, which might be a potential agent for AD treatment.

Protective effect of 5,6,7,8-Tetrahydroxyflavone on high altitude cerebral edema in rats

High altitude cerebral edema (HACE) is a potentially life-threatening disease encountered at high altitudes. However, effective methods for HACE prophylaxis are limited. Convincing evidence confirms that oxidative stress induced by hypobaric hypoxia (HH) is one of the main factors that account for the development of HACE. 5,6,7,8-Tetrahydroxyflavone (THF), a flavone with four consecutive OH groups in ring A, exhibited excellent antioxidant activity in vitro and could attenuate HH induced injury in vivo. The aim of this study was to investigate the protective effect of THF against HACE and its underlying mechanisms. THF administration significantly suppressed HH induced oxidative stress by reducing the formation of hydrogen peroxide and malondialdehyde, by increasing the levels of glutathione and superoxide dismutase in brain tissue. Simultaneously, THF administration inhibited inflammatory responses by decreasing the levels of tumor necrosis factor-α, interleukin-1β, and interleukin-6 in serum and brain tissue. In addition, THF administration mitigated the energy metabolism disorder induced by HACE as evidenced by decreased levels of lactic acid, lactate dehydrogenase and pyruvate kinase as well as increased ATP levels and ATPase activities. Furthermore, THF administration decreased the expression of matrix metalloproteinase-9, aquaporin 4, hypoxia-inducible factor-1α and vascular endothelial growth factor, which attenuated blood-brain barrier (BBB) disruption and brain edema. Additionally, THF administration improved HACE induced cognitive dysfunction. These results show that THF is a promising agent in the prevention and treatment of HACE.

Anti-Inflammatory Effects of GM1 Ganglioside on Endotoxin-Induced Uveitis in Rats

Exogenous ganglioside GM1 has been reported to exert an immunomodulatory effect. We investigated the anti-inflammatory effect of GM1 ganglioside on endotoxin-induced uveitis (EIU) in rats and RAW 264.7 macrophages. Methods: EIU was induced in Lewis rats by administering a subcutaneous injection of lipopolysaccharide (LPS). GM1 was injected intraperitoneally for three consecutive days prior to the LPS injection. Twenty-four hours after the LPS injection, the integrity of the blood-aqueous barrier was evaluated by determining the protein concentration and number of infiltrating cells in the aqueous humor (AqH). Immunohistochemical and Western blot analyses of the iris-ciliary body (ICB) were performed to evaluate the effect of GM1 on the LPS-induced expression of cyclooxygenase-2 (COX-2) and intercellular adhesion molecule-1 (ICAM-1). The effect of GM1 on proinflammatory mediators and signaling cascades was examined in LPS-stimulated RAW 264.7 cells using Western blotting and immunofluorescence staining to further clarify the underlying anti-inflammatory mechanism. Results: GM1 significantly reduced the protein concentration and number of infiltrating cells in the AqH of rats with EIU. GM1 also decreased the LPS-induced expression of the ICAM-1 and COX-2 proteins in the ICB. In RAW 264.7 cells, GM1 inhibited the proinflammatory mediators induced by LPS, including inducible nitric oxide synthase (iNOS), COX-2, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), and this inhibitory effect was potentially mediated by suppressing transforming growth factor-β-activated kinase 1 (TAK1) and reactive oxygen species (ROS)-mediated activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs). Conclusions: Based on this study, GM1 may be a potential anti-inflammatory agent for ocular inflammatory diseases.

Meldonium Ameliorates Hypoxia-Induced Lung Injury and Oxidative Stress by Regulating Platelet-Type Phosphofructokinase-Mediated Glycolysis

Hypoxic environments at high altitudes influence the long-term non-altitude health of residents, by inducing changes in metabolism and the mitochondria, severe lung injury, and endangering life. This study was aimed to determine whether meldonium can ameliorate hypoxia-induced lung injury and investigate its possible molecular mechanisms. We used Swiss mice and exposed type Ⅱ alveolar epithelial cell to hypobaric hypoxic conditions to induce lung injury and found that meldonium has significant preventive effect, which was associated with the regulation of glycolysis. We found using human proteome microarrays assay, molecular docking, immunofluorescence and pull-down assay that the target protein of meldonium is a platelet-type phosphofructokinase (PFKP), which is a rate-limiting enzyme of glycolysis. Also, meldonium promotes the transfer of nuclear factor erythroid 2-related factor 2 (Nrf2) from the cytoplasm to the nucleus, which mitigates oxidative stress and mitochondrial damage under hypoxic condition. Mechanistically, meldonium ameliorates lung injury by targeting PFKP to regulate glycolysis, which promotes Nrf2 translocation from the cytoplasm to the nucleus to alleviate oxidative stress and mitochondrial damage under hypoxic condition. Our study provides a novel potential prevention and treatment strategy against hypoxia-induced lung injury.

A bioactive gypenoside (GP-14) alleviates neuroinflammation and blood brain barrier (BBB) disruption by inhibiting the NF-κB signaling pathway in a mouse high-altitude cerebral edema (HACE) model

BACKGROUND

Neuroinflammation caused by peripheral lipopolysaccharides (LPS) under hypoxia is a key contributor to the development of high altitude cerebral edema (HACE). Our previous studies have shown that gypenosides and their bioactive compounds prevent hypoxia-induced neural injuries in vitro and in vivo. However, their effect on neuroinflammation-related HACE remains to be illustrated. The present study aimed to investigate the effects of GP-14 in HACE mouse model.

METHODS

HACE mice were treated with GP-14 (100 and 200 mg/kg) for 7 days. After the treatments, the level of serum inflammation cytokines and the transcription of inflammatory factors in brain tissue were determined. The activation of microglia, astrocyte and the changes of IgG leakage and the protein levels of tight junction proteins were detected. Furthermore, the inflammatory factors and nuclear factor-κB (NF-κB) signaling pathway in BV-2 cells and primary microglia were detected.

RESULTS

GP-14 pretreatment alleviated both the serum and neural inflammatory responses caused by LPS stimulation combined with hypobaric hypoxia exposure. In addition, GP-14 pretreatment inhibited microglial activation, accompanied by a decrease in the M1 phenotype and an increase in the M2 phenotype. Moreover, the disruption of the blood brain barrier (BBB) integrity, including increased IgG leakage and decreased expression of tight junction proteins, was attenuated by GP-14 pretreatment. Based on the BV-2 and primary microglial models, the inflammatory response and activation of the NF-κB signaling pathway were also inhibited by GP-14 pretreatment.

CONCLUSION

Taken together, our results demonstrated that GP-14 exhibited prominent protective roles against neuroinflammation and BBB disruption in a mouse HACE model. GP-14 could be a potential choice for the treatment of HACE in the future.

High Altitude Cerebral Edema: Improving Treatment Options

High altitude illness in its most severe form can lead to high altitude cerebral edema (HACE). Current strategies have focused on prevention with graduated ascents, pharmacologic prophylaxis, and descent at first signs of symptoms. Little is understood regarding treatment with steroids and oxygenation being commonly utilized. Pre-clinical studies with turmeric derivatives have offered promise due to its anti-inflammatory and antioxidant properties, but they warrant validation clinically. Ongoing work is focused on better understanding the disease pathophysiology with an emphasis on the glymphatic system and venous outflow obstruction. This review highlights what is known regarding diagnosis, treatment, and prevention, while also introducing novel pathophysiology mechanisms warranting further investigation.

Oxidative Stress and Diseases Associated with High-Altitude Exposure

Several diseases associated with high-altitude exposure affect unacclimated individuals. These diseases include acute mountain sickness (AMS), high-altitude cerebral edema (HACE), high-altitude pulmonary edema (HAPE), chronic mountain sickness (CMS), and, notably, high-altitude pulmonary hypertension (HAPH), which can eventually lead to right ventricle hypertrophy and heart failure. The development of these pathologies involves different molecules and molecular pathways that might be related to oxidative stress. Studies have shown that acute, intermittent, and chronic exposure to hypobaric hypoxia induce oxidative stress, causing alterations to molecular pathways and cellular components (lipids, proteins, and DNA). Therefore, the aim of this review is to discuss the oxidative molecules and pathways involved in the development of high-altitude diseases. In summary, all high-altitude pathologies are related to oxidative stress, as indicated by increases in the malondialdehyde (MDA) biomarker and decreases in superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant activity. In addition, in CMS, the levels of 8-iso-PGF2α and H₂O₂ are increased, and evidence strongly indicates an increase in Nox4 activity in HAPH. Therefore, antioxidant treatments seem to be a promising approach to mitigating high-altitude pathologies.

Anti-inflammatory role of GM1 and other gangliosides on microglia

Background

Gangliosides are glycosphingolipids highly enriched in the brain, with important roles in cell signaling, cell-to-cell communication, and immunomodulation. Genetic defects in the ganglioside biosynthetic pathway result in severe neurodegenerative diseases, while a partial decrease in the levels of specific gangliosides was reported in Parkinson’s disease and Huntington’s disease. In models of both diseases and other conditions, administration of GM1—one of the most abundant gangliosides in the brain—provides neuroprotection. Most studies have focused on the direct neuroprotective effects of gangliosides on neurons, but their role in other brain cells, in particular microglia, is not known. In this study we investigated the effects of exogenous ganglioside administration and modulation of endogenous ganglioside levels on the response of microglia to inflammatory stimuli, which often contributes to initiation or exacerbation of neurodegeneration.

Methods

In vitro studies were performed using BV2 cells, mouse, rat, and human primary microglia cultures. Modulation of microglial ganglioside levels was achieved by administration of exogenous gangliosides, or by treatment with GENZ-123346 and L–t-PDMP, an inhibitor and an activator of glycolipid biosynthesis, respectively. Response of microglia to inflammatory stimuli (LPS, IL-1β, phagocytosis of latex beads) was measured by analysis of gene expression and/or secretion of pro-inflammatory cytokines. The effects of GM1 administration on microglia activation were also assessed in vivo in C57Bl/6 mice, following intraperitoneal injection of LPS.

Results

GM1 decreased inflammatory microglia responses in vitro and in vivo, even when administered after microglia activation. These anti-inflammatory effects depended on the presence of the sialic acid residue in the GM1 glycan headgroup and the presence of a lipid tail. Other gangliosides shared similar anti-inflammatory effects in in vitro models, including GD3, GD1a, GD1b, and GT1b. Conversely, GM3 and GQ1b displayed pro-inflammatory activity. The anti-inflammatory effects of GM1 and other gangliosides were partially reproduced by increasing endogenous ganglioside levels with L–t-PDMP, whereas inhibition of glycolipid biosynthesis exacerbated microglial activation in response to LPS stimulation.

Conclusions

Our data suggest that gangliosides are important modulators of microglia inflammatory responses and reveal that administration of GM1 and other complex gangliosides exerts anti-inflammatory effects on microglia that could be exploited therapeutically.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02374-x.

Compound Danshen Dripping Pill inhibits high altitude-induced hypoxic damage by suppressing oxidative stress and inflammatory responses

CONTEXT

Previous studies indicate that compound Danshen Dripping Pill (CDDP) improves the adaptation to high-altitude exposure. However, its mechanism of action is not clear.

OBJECTIVE

To explore the protective effect of CDDP on hypobaric hypoxia (HH) and its possible mechanism.

MATERIALS AND METHODS

A meta-analysis of 1051 human volunteers was performed to evaluate the effectiveness of CDDP at high altitudes. Male Sprague-Dawley rats were randomized into 5 groups (n = 6): control at normal pressure, model, CDDP-170 mg/kg, CDDP-340 mg/kg and acetazolamide groups. HH was simulated at an altitude of 5500 m for 24 h. Animal blood was collected for arterial blood-gas analysis and cytokines detection and their organs were harvested for pathological examination. Expression levels of AQP1, NF-κB and Nrf2 were determined by immunohistochemical staining.

RESULTS

The meta-analysis data indicated that the ratio between the combined RR of the total effective rate and the 95% CI was 0.23 (0.06, 0.91), the SMD and 95% CI of SO₂ was 0.37 (0.12, 0.62). Pre-treatment of CDDP protected rats from HH-induced pulmonary edoema and heart injury, left-shifted oxygen-dissociation curve and decreased P50 (30.25 ± 3.72 vs. 37.23 ± 4.30). Mechanistically, CDDP alleviated HH-reinforced ROS by improving SOD and GPX1 while inhibiting pro-inflammatory cytokines and NF-κB expression. CDDP also decreased HH-evoked D-dimer, erythrocyte aggregation and blood hemorheology, promoting AQP1 and Nrf2 expression.

DISCUSSION AND CONCLUSIONS

Pre-treatment with CDDP could prevent HH-induced tissue damage, oxidative stress and inflammatory response. Suppressed NF-κB and up-regulated Nrf2 might play significant roles in the mechanism of CDDP.

Monosialotetrahexosylganglioside in the treatment of chronic oxaliplatin-induced peripheral neurotoxicity: TJMUCH-GI-001, a randomised controlled trial

BACKGROUND

Chronic oxaliplatin-induced peripheral neurotoxicity (OIPN) is the most troublesome and dose-limiting side effect of oxaliplatin. There is no effective treatment for chronic OIPN. We conducted a randomised controlled trial to investigate the efficacy of monosialotetrahexosylganglioside (GM1) in treating chronic OIPN.

METHODS

In this single-centre, double-blind, phase Ⅲ trial, gastrointestinal cancer patients with persistent chronic OIPN were randomised in 1:1 ratio to receive either GM1 or placebo at Tianjin Medical University Cancer Institute and Hospital, China. GM1 was dosed at 60 mg daily for every 3 weeks or 40 mg daily for every 2 weeks. Seven- and fourteen- day infusions were administered to concurrent oxaliplatin users and oxaliplatin discontinuation patients, respectively. The primary endpoint was the relief of neurotoxicity (≥30% improvement), measured by a newly developed patient reported outcome measure (MCIPN) based on prior questionnaires including the European Organization for Research and Treatment of Cancer Quality of Life Chemotherapy Induced Peripheral Neuropathy Questionnaire twenty-item scale. Visual analogue score (VAS) was used as another instrument for patients to evaluate the total Chronic OIPN treatment effect. VAS responders (≥30% improvement), double responders (≥30% improvement in both MCIPN and VAS), and high responders (≥50% improvement in the MCIPN total score) were also calculated. The secondary endpoints were safety and quality of life. The additional endpoints are progression-free survival (PFS), disease-free survival (DFS), overall survival (OS), and tumour response. (Trial registration number: NCT02486198 at ClinicalTrials.gov).

FINDINGS

Between May 2015 to December 2017, 145 patients were randomly assigned to receive either GM1 (n=73) and placebo (n=72). Majority of the patients in both arms (90% in GM1 and 83% in placebo) continued receiving oxaliplatin on the trial. More patients responded in the GM1 group than in the placebo group (MCIPN responders: 53% vs 14%, VAS responders: 49% vs 22%, double responders: 41% vs 7%, and high responders: 32% vs 13%, all P < ·01). Analyses were also performed in concurrent oxaliplatin users. The results were consistent with those of the whole group. No deleterious effects of GM1 on survival or tumour response were found. There were no ≥G3 GM1-related adverse events.

INTERPRETATION

In patients with chronic OIPN, the use of GM1 reduces the severity of chronic OIPN compared with placebo.

FUNDING

This work was supported by clinical trial development fund of Tianjin Medical University Cancer Institute and Hospital (No.C1706).

Protective effects of active compounds from on heart and brain of mice at simulated high altitude

To investigate the active compounds from on the heart and brain of mice at simulated high altitude.Fifty healthy male adult BALB/c mice were randomly divided into normal control group, hypoxic model group, acetazolamide group, petroleum ether extract of (PESI) group and octacosan group with 10 mice in each group. Acetazolamide group, PESI group and octacosan group were treated with acetazolamide PESI (200 mg/kg) or octacosan by single tail vein injection, respectively. Except normal control group, the mice were exposed to a simulated high altitude of for in an animal decompression chamber. After the mice were sacrificed by cervical dislocation, the heart and brain were histologically observed by HE staining; superoxide dismutase (SOD) activity, total anti-oxidant capacity (T-AOC) and the content of malondialdehyde (MDA) in plasma, heart and brain tissues were detected by WST-1 method, ABTS method and TBA method, respectively; lactic acid and lactate dehydrogenase (LDH) activity in plasma, heart and brain tissues were detected by colorimetric method and microwell plate method, respectively; ATP content and ATPase activity in heart and brain tissues were detected by colorimetric method. PESI and octacosane significantly attenuated the pathological damages of heart and brain tissue at simulated high altitude; increased SOD activity, T-AOC and LDH activity, and decreased the contents of MDA and lactic acid in plasma, heart and brain tissues; increased the content of ATP in heart and brain tissues; increased the activities of Na-K ATPase, Mg ATPase, Ca ATPase and Ca-Mg ATPase in myocardial tissue; and increased the activities of Mg ATPase, Ca-Mg ATPase in brain tissue. PESI and octacosan exert anti-hypoxic activity by improving the antioxidant capacity, reducing the free radical levels, promoting the anaerobic fermentation, and alleviating the energy deficiency and metabolic disorders caused by hypoxia in mice.

Targeting strategies for oxaliplatin-induced peripheral neuropathy: clinical syndrome, molecular basis, and drug development

Oxaliplatin (OHP)-induced peripheral neurotoxicity (OIPN) is a severe clinical problem and potentially permanent side effect of cancer treatment. For the management of OIPN, accurate diagnosis and understanding of significant risk factors including genetic vulnerability are essential to improve knowledge regarding the prevalence and incidence of OIPN as well as enhance strategies for the prevention and treatment of OIPN. The molecular mechanisms underlying OIPN are complex, with multi-targets and various cells causing neuropathy. Furthermore, mechanisms of OIPN can reinforce each other, and combination therapies may be required for effective management. However, despite intense investigation in preclinical and clinical studies, no preventive therapies have shown significant clinical efficacy, and the established treatment for painful OIPN is limited. Duloxetine is the only agent currently recommended by the American Society of Clinical Oncology. The present article summarizes the most recent advances in the field of studies on OIPN, the overview of the clinical syndrome, molecular basis, therapy development, and outlook of future drug candidates. Importantly, closer links between clinical pain management teams and oncology will advance the effectiveness of OIPN treatment, and the continued close collaboration between preclinical and clinical research will facilitate the development of novel prevention and treatments for OIPN.

Gangliosides combined with mild hypothermia provides neuroprotection in a rat model of traumatic brain injury

Traumatic brain injury (TBI) remains a major cause of disability and death in modern society. In this study, we explored the neuroprotection role of the combination of gangliosides (GM) and mild hypothermia (MH) and the potential effect on oxidative stress injuries in a rat model of TBI. All 50 rats were randomized to five groups: (1) NC group: undergoing surgery without hit; (2) TBI group: undergoing surgery with hit; (3) GM group: TBI treated with gangliosides; (4) MHT group: TBI treated with MH; (5) GM+MHT group: TBI treated with gangliosides and MH. Spatial learning impairments, neurological function injury, Evans Blue leakage, brain MRI and oxidative stress injuries were assessed. The protein levels of Cleaved-caspase 3 and CytC were also detected. Both GM and MHT could rescue TBI-induced spatial learning impairments, improve neurological function injury and brain edema. In addition, the combination of them has a better therapeutic effect. Through the MRI, we found that compared with the TBI group, the brain tissue edema area of GM group, MHT group, and GM+MHT group was smaller, the occupancy effect was weakened, and the midline was slightly shifted. Compared with the GM group and MHT group, these changes in the GM+MHT group were much smaller. GM combined with MH-alleviated TBI-induced oxidative stress injuries and apoptosis. Our study reveals that GM and MH potentially provide neuroprotection via the suppression of oxidative stress injuries and apoptosis after TBI in rats.

Tibetan medicine Duoxuekang ameliorates hypobaric hypoxia-induced brain injury in mice by restoration of cerebrovascular function

ETHNOPHARMACOLOGICAL RELEVANCE

Duoxuekang (DXK, ཁྲག་འཕེལ་བདེ་བྱེད།) is a clinical experience prescription of CuoRu-Cailang, a famous Tibetan medicine master, which has effective advantages in the treatment of hypobaric hypoxia (HH)-induced brain injury. However, its underlying mechanisms remain unclear.

AIM OF THE STUDY

The present study was designed to investigate the effects of DXK on cerebrovascular function of HH-induced brain injury in mice.

MATERIALS AND METHODS

DSC-MR imaging was used to evaluate the effect of DXK on the brain blood perfusion of patients with hypoxic brain injury. HPLC analysis was used to detect the content of salidroside, gallic acid, tyrosol, corilagin, ellagic acid, isorhamnetin, quercetin and gingerol in DXK. The model of HH-induced brain injury in mice was established by an animal hypobaric and hypoxic chamber. The BABL/c mice were randomly divided into six groups: control group, model group, Hongjingtian oral liquid group (HOL, 3.3 ml/kg) and DXK groups (0.9, 1.8 and 3.6 g/kg). All mice (except the control group) were intragastrically administrated for a continuous 7 days and put into the animal hypobaric and hypoxic chamber after the last intragastric administration. Hematoxylin-eosin staining was employed to evaluate the pathological changes of brain tissue. Masson and Weigert stainings were used to detect the content of collagen fibers and elastic fibers of brain, respectively. Routine blood test and biochemical kits were used to analyze hematological parameters and oxidative stress indices. Immunofluorescence staining was applied to detect the protein levels of VEGF, CD31/vWF and α-SMA.

RESULTS

The results of DSC-MR imaging confirmed that DXK can increased CBV in the left temporal lobe while decreased MTT in the right frontal lobe, right temporal lobe and right occipital lobe of the brain. DXK contains salidroside, gallic acid, tyrosol, corilagin, ellagic acid, isorhamnetin, quercetin and gingerol. Compared with the model group, DXK can ameliorate the atrophy and deformation, and increase the number of pyramidal neurons in hippocampal CA3 area and cortical neurocytes. Masson and Weigert stainings results revealed that DXK can significantly increase the content of collagen fibers and elastic fibers in brain. Routine blood test results demonstrated that DXK can dramatically decrease the levels of WBC, MCH and MCHC, while increase RBC, HGB, HCT, MCV and PLT in the blood samples. Biochemical results revealed that DXK can markedly increase SOD, CAT and GSH activities, while decrease MDA activity. Immunofluorescence revealed that DXK can notably increase the protein levels of VEGF, CD31/vWF and α-SMA.

CONCLUSIONS

In conclusion, this study proved that DXK can ameliorate HH-induced brain injury by improving brain blood perfusion, increasing the number of collagen and elastic fibers and inhibiting oxidative stress injury. The underlying mechanisms may be involved in maintaining the integrity of cerebrovascular endothelial cells and vascular function. However, further in vivo and in vitro investigations are still needed to elucidate the mechanisms of DXK on regulating cerebral blood vessels.

Cattle Encephalon Glycoside and Ignotin Protects Neurons Against Microglia-Induced Neuroinflammation via Elevating BDNF Expression and Inhibiting TLR4/NF-κB Pathway

Neuroinflammation is involved in the pathology and progression of Alzheimer's disease (AD) and is closely related to microglial activation. We have previously reported that cattle encephalon glycoside and ignotin (CEGI) could inhibit the activation of microglia in APP/PS1 mice, a mouse model of familial AD. However, the anti-neuroinflammatory mechanisms of CEGI have not yet been fully elucidated. Here, we aimed to investigate the role of CEGI in microglia-mediated neuroinflammation in AD. APP/PS1 mice were treated with CEGI intraperitoneally for 30 days, and then their cognition was assessed. We showed that CEGI alleviated cognitive damage with higher nesting scores, preferential indices, and spontaneous alternation rates in APP/PS1 mice. Moreover, CEGI treatment effectively reduced microglial activation and Iba-1 levels in the cortex of APP/PS1 mice. Additionally, CEGI decreased pro-inflammatory factors production and neuroinflammation-mediated neuronal damage in vivo and in vitro. Finally, CEGI upregulated BDNF levels and downregulated TLR4 and p-NF-κB p65 levels in vivo and in vitro. Taken together, these findings indicated that CEGI could attenuate cognitive deficits in APP/PS1 mice and suppress microglia-induced neuroinflammation via increasing BDNF expression and inhibiting the TLR4/NF-κB pathway.

Kaempferol Inhibits Zearalenone-Induced Oxidative Stress and Apoptosis via the PI3K/Akt-Mediated Nrf2 Signaling Pathway: In Vitro and In Vivo Studies

In this study, kaempferol (KFL) shows hepatoprotective activity against zearalenone (ZEA)-induced oxidative stress and its underlying mechanisms in in vitro and in vivo models were investigated. Oxidative stress plays a critical role in the pathophysiology of various hepatic ailments and is normally regulated by reactive oxygen species (ROS). ZEA is a mycotoxin known to exert toxicity via inflammation and ROS accumulation. This study aims to explore the protective role of KFL against ZEA-triggered hepatic injury via the PI3K/Akt-regulated Nrf2 pathway. KFL augmented the phosphorylation of PI3K and Akt, which may stimulate antioxidative and antiapoptotic signaling in hepatic cells. KFL upregulated Nrf2 phosphorylation and the expression of antioxidant genes HO-1 and NQO-1 in a dose-dependent manner under ZEA-induced oxidative stress. Nrf2 knockdown via small-interfering RNA (siRNA) inhibited the KFL-mediated defence against ZEA-induced hepatotoxicity. In vivo studies showed that KFL decreased inflammation and lipid peroxidation and increased H₂O₂ scavenging and biochemical marker enzyme expression. KFL was able to normalize the expression of liver antioxidant enzymes SOD, CAT and GSH and showed a protective effect against ZEA-induced pathophysiology in the livers of mice. These outcomes demonstrate that KFL possesses notable hepatoprotective roles against ZEA-induced damage in vivo and in vitro. These protective properties of KFL may occur through the stimulation of Nrf2/HO-1 cascades and PI3K/Akt signaling.

Establishment of an experimental rat model of high altitude cerebral edema by hypobaric hypoxia combined with temperature fluctuation

High altitude cerebral edema (HACE) is a kind of life threat disease encountered at high altitude, but the precise pathogenesis of it is far more understood. Hypobaic hypoxia (HH) and cold are conditions characteristic of high altitude environment. HH is always considered as the central causative factor for the development of HACE, but the effect of cold stress on HACE has been rarely investigated. The purpose of this study was to investigate the potential role of cold stress in the development of HACE and establish a stable experimental animal model. Male SPF Wistar rats were randomly divided into five groups for this experiment, control group (altitude, 1400 m, temperature, 25 ℃), NC + 2 ℃ group (altitude, 1400 m, temperature, 2 ℃), HH group (altitude, 6000 m, temperature, 25 ℃), HH+2 ℃ group (altitude, 6000 m, temperature, 2 ℃) and HH + 12/2 ℃ (altitude, 6000 m, temperature, 12 ℃/2 ℃ light/dark cycle). After exposure for 72 h, the blood and brain tissues were collected. Brain water content (BWC) and Evans Blue dye extravasation were used to assess the brain edema and blood-brain barrier (BBB) permeability, respectively. The levels of pro-inflammatory cytokines in serum were assessed via enzyme-linked immunosorbent assay. Oxidative stress markers and ATPase activity were determined using commercial kits. Western blotting was used to detect the expression of related proteins. Compared to control, HH+2 ℃ could significantly increase the BWC and BBB permeability, and these changes were further exacerbated by HH + 12/2 ℃. Furthermore, HH+2 ℃ and HH + 12/2 ℃ markedly increased the levels of H₂O₂ and MDA, restrained SOD and GSH levels and decreased Na⁺/K⁺-ATPase activitie compared with the control group. In addition, HH+2 ℃ and HH + 12/2 ℃ enhanced the levels of pro-inflammatory cytokines IL-1β, TNF-α and IL-6 in serum and significantly increased the expression of VEGF in brain compared with the control group, but only HH + 12/2 ℃ could increase the expression of AQP4. However, compared with control group, no significant differences in these parameters were observed in HH and NC+2 ℃groups. These results demonstrated that HH or cold stress alone did not successfully induce brain damage, while HH+2 ℃ could induce the onset of HACE via provoking injury caused by HH. HH + 12/2 ℃ was more obvious and efficient. Collectively, we firstly suggest that cold stress may promote the formation of HACE by aggravating the brain injury induced by HH exposure and supply an effective and reliable experimental rat model of HACE via HH combined with temperature fluctuation.

Targeting Transcription Factor Nrf2 (Nuclear Factor Erythroid 2-Related Factor 2) for the Intervention of Vascular Cognitive Impairment and Dementia

Vascular cognitive impairment and dementia (VCID) is an age-related, mild to severe mental disability due to a broad panel of cerebrovascular disorders. Its pathobiology involves neurovascular dysfunction, blood-brain barrier disruption, white matter damage, microRNAs, oxidative stress, neuroinflammation, and gut microbiota alterations, etc. Nrf2 (Nuclear factor erythroid 2-related factor 2) is the master regulator of redox status and controls the transcription of a panel of antioxidative and anti-inflammatory genes. By interacting with NF-κB (nuclear factor-κB), Nrf2 also fine-tunes the cellular oxidative and inflammatory balance. Aging is associated with Nrf2 dysfunction, and increasing evidence has proved the role of Nrf2 in mitigating the VCID process. Based on VCID pathobiologies and Nrf2 studies from VCID and other brain diseases, we point out several hypothetical Nrf2 targets for VCID management, including restoration of endothelial function and neurovascular coupling, preservation of blood-brain barrier integrity, reduction of amyloidopathy, promoting white matter integrity, and mitigating oxidative stress and neuroinflammation. Collectively, the Nrf2 pathway could be a promising direction for future VCID research. Targeting Nrf2 would shed light on VCID managing strategies.

Gangliosides in the Brain: Physiology, Pathophysiology and Therapeutic Applications

Gangliosides are glycosphingolipids highly abundant in the nervous system, and carry most of the sialic acid residues in the brain. Gangliosides are enriched in cell membrane microdomains ("lipid rafts") and play important roles in the modulation of membrane proteins and ion channels, in cell signaling and in the communication among cells. The importance of gangliosides in the brain is highlighted by the fact that loss of function mutations in ganglioside biosynthetic enzymes result in severe neurodegenerative disorders, often characterized by very early or childhood onset. In addition, changes in the ganglioside profile (i.e., in the relative abundance of specific gangliosides) were reported in healthy aging and in common neurological conditions, including Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), stroke, multiple sclerosis and epilepsy. At least in HD, PD and in some forms of epilepsy, experimental evidence strongly suggests a potential role of gangliosides in disease pathogenesis and potential treatment. In this review, we will summarize ganglioside functions that are crucial to maintain brain health, we will review changes in ganglioside levels that occur in major neurological conditions and we will discuss their contribution to cellular dysfunctions and disease pathogenesis. Finally, we will review evidence of the beneficial roles exerted by gangliosides, GM1 in particular, in disease models and in clinical trials.

Gangliosides and Neuroblastomas

The focus of this review is the ganglio-series of glycosphingolipids found in neuroblastoma (NB) and the myriad of unanswered questions associated with their possible role(s) in this cancer. NB is one of the more common solid malignancies of children. Five-year survival for those diagnosed with low risk NB is 90-95%, while that for children with high-risk NB is around 40-50%. Much of the survival rate reflects age of diagnosis with children under a year having a much better prognosis than those over two. Identification of expression of GD2 on the surface of most NB cells led to studies of the effectiveness and subsequent approval of anti-GD2 antibodies as a treatment modality. Despite much success, a subset of patients, possibly those whose tumors fail to express concentrations of gangliosides such as GD1b and GT1b found in tumors from patients with a good prognosis, have tumors refractory to treatment. These observations support discussion of what is known about control of ganglioside synthesis, and their actual functions in NB, as well as their possible relationship to treatment response.

Rosamultin Attenuates Acute Hypobaric Hypoxia-Induced Bone Injuries by Regulation of Sclerostin and Its Downstream Signals

Wang, Xing-Min, Hui Liu, Jian-Yu Li, Jin-Xia Wei, Xia Li, Yong-Liang Zhang, Ling-Zhi Li, and Xi-Zheng Zhang. Rosamultin attenuates acute hypobaric hypoxia-induced bone injuries by regulation of sclerostin and its downstream signals. High Alt Med Biol. 21:273-286, 2020. Background: Rosamultin, one of the compounds extracted from Potentilla anserina L., exhibited significant pharmacological activity against oxidative stress and hypoxic injury in our previous study. However, the effect of rosamultin on bone damage induced by acute hypobaric hypoxia (HH) has not been thoroughly studied. Methods: In this study, we first investigated the protective effect of rosamultin against bone damage in rats following acute exposure to simulated high-altitude hypoxia. Furthermore, we explored the detailed mechanism involved in the regulation of rat bone remodeling by rosamultin in an acute HH environment through analysis of sclerostin expression and the regulation of downstream signaling pathways. Results: Pretreatment with rosamultin significantly reduced HH-induced oxidative stress and inflammation, improved bone metabolic abnormalities, and alleviated the imbalance in bone remodeling in rats exposed to acute HH. Rosamultin markedly downregulated the expression of sclerostin, activated the Wnt/β-catenin signaling pathway, and enhanced the ratio of osteoprotegerin/receptor activator of nuclear factor kappa B ligand to maintain the balance of bone formation and resorption. Conclusions: Rosamultin attenuates acute HH-induced bone damage and improves abnormal bone remodeling in rats by inhibition of sclerostin expression and activation of the Wnt/β-catenin signaling pathway.

Tetrahydrocurcumin mitigates acute hypobaric hypoxia-induced cerebral oedema and inflammation through the NF-κB/VEGF/MMP-9 pathway

High-altitude cerebral oedema (HACE) is a potentially fatal manifestation of high-altitude sickness and is caused partly by inflammation and the blood-brain barrier disruption. Tetrahydrocurcumin (THC) has been reported to exert effective antioxidative and anti-inflammatory effects; This study sought to elucidate the underlying mechanism of THC in mitigating HACE using a mouse model. Our results revealed that prophylactic administration of THC (40 mg/kg) for 3 days significantly alleviated the increase in brain water content (BWC), interleukin-1β (IL-1β) and TNF-α levels caused by acute hypobaric hypoxia (AHH). Additionally, superoxide dismutase (SOD) activity was increased by THC to enhance the ability to resist hypoxia. Histological and ultrastructural analysis of the cerebrum revealed that THC administration mitigated AHH-induced pericellular oedema and reduced the perivascular space, resulting in the simultaneous remission of oedema and protection of mitochondria in the cerebrum. In vitro, astrocytes exposed to hypoxia (4% O₂ ) for 24 hr exhibited and increase in IL-1β expression followed by an increase in vascular endothelial growth factor (VEGF) levels. Furthermore, THC administration remarkably downregulated VEGF, matrix metallopeptidase-9 (MMP-9), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) expression, both in vivo and in vitro. Our data highlight the potential prophylactic activity of THC in HACE, it effectively mitigates AHH-induced cerebral oedema and inflammation is associated with the inhibition of the NF-κB/ VEGF/MMP-9 pathways.

Polysaccharide extracted from Potentilla anserina L ameliorate acute hypobaric hypoxia-induced brain impairment in rats

High altitude cerebral edema (HACE) is a high altitude malady caused by acute hypobaric hypoxia (AHH), in which pathogenesis is associated with oxidative stress and inflammatory cytokines. Potentilla anserina L is mainly distributed in Tibetan Plateau, and its polysaccharide possesses many physiological and pharmacological properties. In the present study, the protective effect and potential treatment mechanism of Potentilla anserina L polysaccharide (PAP) in HACE were explored. First, we measured the brain water content and observed the pathological changes in brain tissues, furthermore, malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), and glutathione (GSH) were evaluated by kits. Finally, the protein contents and mRNA expressions of pro-inflammatory (IL-1β, IL-6, TNF-α, vascular endothelial cell growth factor [VEGF], NF-κB, and hypoxia inducible factor-1 α [HIF-1α]) were detected by ELISA kits, RT-PCR, and western blotting. The results demonstrated that PAP reduced the brain water content, alleviated brain tissue injury, reduce the levels of MDA and NO, and increased the activity of SOD and GSH level. In addition, PAP blocking the NF-κB and HIF-1α signaling pathway activation inhibited the generation of downstream pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and VEGF). Therefore, PAP has a potential to treat and prevent of HACE by suppression of oxidative stress and inflammatory response.

Investigation of the gene co-expression network and hub genes associated with acute mountain sickness

Background

Acute mountain sickness has become a heavily researched topic in recent years. However, the genetic mechanism and effects have not been elucidated. Our goal is to construct a gene co-expression network to identify the key modules and hub genes associated with high altitude hypoxia.

Results

The GSE46480 dataset of rapidly transported healthy adults with acute mountain sickness was selected and analyzed by weighted gene co-expression network analysis (WGCNA) to construct a co-expression network. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the data set were carried out using Database for Annotation Visualization and Integrated Discovery (DAVID), and the hub genes were selected. We found that the turquoise module was most significantly correlated with acute mountain sickness. The functional enrichment analysis showed that the turquoise module was related to the apoptotic process, protein transport, and translation processes. The metabolic pathway analysis identified hsa03010:ribosome and hsa04144:endocytosis as the most important pathways in the turquoise module. Ten top 10 hub genes (MRPL3, PSMC6, AIMP1, HAT1, DPY30, ATP5L, COX7B, UQCRB, DPM1, and COMMD6) for acute mountain sickness were identified.

Conclusion

One module and 10 hub genes were identified, which were related to acute mountain sickness. The reference provided by this module may help to elucidate the mechanism of acute mountain sickness. In addition, the hub genes may be used in the future as a biomarker and therapeutic target for accurate diagnosis and treatment.

Neurotrophic effects of GM1 ganglioside, NGF, and FGF2 on canine dorsal root ganglia neurons in vitro

Dogs share many chronic morbidities with humans and thus represent a powerful model for translational research. In comparison to rodents, the canine ganglioside metabolism more closely resembles the human one. Gangliosides are components of the cell plasma membrane playing a role in neuronal development, intercellular communication and cellular differentiation. The present in vitro study aimed to characterize structural and functional changes induced by G_M1 ganglioside (G_M1) in canine dorsal root ganglia (DRG) neurons and interactions of G_M1 with nerve growth factor (NGF) and fibroblast growth factor (FGF2) using immunofluorescence for several cellular proteins including neurofilaments, synaptophysin, and cleaved caspase 3, transmission electron microscopy, and electrophysiology. G_M1 supplementation resulted in increased neurite outgrowth and neuronal survival. This was also observed in DRG neurons challenged with hypoxia mimicking neurodegenerative conditions due to disruptions of energy homeostasis. Immunofluorescence indicated an impact of G_M1 on neurofilament phosphorylation, axonal transport, and synaptogenesis. An increased number of multivesicular bodies in G_M1 treated neurons suggested metabolic changes. Electrophysiological changes induced by G_M1 indicated an increased neuronal excitability. Summarized, G_M1 has neurotrophic and neuroprotective effects on canine DRG neurons and induces functional changes. However, further studies are needed to clarify the therapeutic value of gangliosides in neurodegenerative diseases.

Neuroprotective effect of CPCGI on Alzheimer's disease and its mechanism

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder causing progressive memory loss and cognitive impairment. The aberrant accumulation of amyloid‑β (Aβ) and neuroinflammation are two major events in AD. Aβ‑induced neurotoxicity and oxidative stress are also involved in the pathogenesis of AD. The purpose of the current study was to investigate the effect of compound porcine cerebroside and ganglioside injection (CPCGI) on the progression of AD, and to explore the molecular mechanism. In vivo and in vitro models of AD were established and treated with CPCGI. Aβ40 and Aβ42 protein levels were detected using western blotting. Production of pro‑inflammatory factors [tumor necrosis factor (TNF)‑α and interleukin (IL)‑1β] and oxidative stress markers [malondialdehyde (MDA), superoxide dismutase (SOD)] and reactive oxygen species (ROS) production were determined. Cell viability and apoptosis were detected using 3‑(4,5‑dimethyl‑2‑thiazolyl)‑2,5‑​diphenyl‑2‑H‑tetrazolium bromide assay and flow cytometry analysis respectively. Results demonstrated that CPCGI administration reduced Aβ40 and Aβ42 accumulation, and inhibited inflammatory response and oxidative stress in the in vivo rat model of AD, evidenced by decreased Aβ40 and Aβ42 protein expression, reduced levels of TNF‑α and IL‑1β, reduced MDA content, enhanced SOD activity, and reduced ROS level. It was found that CPCGI enhanced cell viability and reduced cell apoptosis of Aβ25‑35 induced PC12 cells. In addition, the mitogen‑activated protein kinase/NF‑κB pathway was involved in the protective effect of CPCGI on AD. Taken together, the data demonstrated that CPCGI exerted a protective effect on AD by reducing Aβ accumulation, inhibiting inflammatory response and oxidative stress, In addition to preventing neuronal apoptosis.

Chemotherapy-induced peripheral neuropathy-part 2: focus on the prevention of oxaliplatin-induced neurotoxicity

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is regarded as one of the most common dose-limiting adverse effects of several chemotherapeutic agents, such as platinum derivatives (oxaliplatin and cisplatin), taxanes, vinca alkaloids and bortezomib. CIPN affects more than 60% of patients receiving anticancer therapy and although it is a nonfatal condition, it significantly worsens patients' quality of life. The number of analgesic drugs used to relieve pain symptoms in CIPN is very limited and their efficacy in CIPN is significantly lower than that observed in other neuropathic pain types. Importantly, there are currently no recommended options for effective prevention of CIPN, and strong evidence for the utility and clinical efficacy of some previously tested preventive therapies is still limited.

METHODS

The present article is the second one in the two-part series of review articles focused on CIPN. It summarizes the most recent advances in the field of studies on CIPN caused by oxaliplatin, the third-generation platinum-based antitumor drug used to treat colorectal cancer. Pharmacological properties of oxaliplatin, genetic, molecular and clinical features of oxaliplatin-induced neuropathy are discussed.

RESULTS

Available therapies, as well as results from clinical trials assessing drug candidates for the prevention of oxaliplatin-induced neuropathy are summarized.

CONCLUSION

Emerging novel chemical structures-potential future preventative pharmacotherapies for CIPN caused by oxaliplatin are reported.

Effects of Gangliosides on Spermatozoa, Oocytes, and Preimplantation Embryos

Gangliosides are sialic acid-containing glycosphingolipids, which are the most abundant family of glycolipids in eukaryotes. Gangliosides have been suggested to be important lipid molecules required for the control of cellular procedures, such as cell differentiation, proliferation, and signaling. GD1a is expressed in interstitial cells during ovarian maturation in mice and exogenous GD1a is important to oocyte maturation, monospermic fertilization, and embryonic development. In this context, GM1 is known to influence signaling pathways in cells and is important in sperm-oocyte interactions and sperm maturation processes, such as capacitation. GM3 is expressed in the vertebrate oocyte cytoplasm, and exogenously added GM3 induces apoptosis and DNA injury during in vitro oocyte maturation and embryogenesis. As a consequence of this, ganglioside GT1b and GM1 decrease DNA fragmentation and act as H2O2 inhibitors on germ cells and preimplantation embryos. This review describes the functional roles of gangliosides in spermatozoa, oocytes, and early embryonic development.

Sphingolipids in Obesity and Correlated Co-Morbidities: The Contribution of Gender, Age and Environment

This paper reviews our present knowledge on the contribution of ceramide (Cer), sphingomyelin (SM), dihydroceramide (DhCer) and sphingosine-1-phosphate (S1P) in obesity and related co-morbidities. Specifically, in this paper, we address the role of acyl chain composition in bodily fluids for monitoring obesity in males and females, in aging persons and in situations of environmental hypoxia adaptation. After a brief introduction on sphingolipid synthesis and compartmentalization, the node of detection methods has been critically revised as the node of the use of animal models. The latter do not recapitulate the human condition, making it difficult to compare levels of sphingolipids found in animal tissues and human bodily fluids, and thus, to find definitive conclusions. In human subjects, the search for putative biomarkers has to be performed on easily accessible material, such as serum. The serum “sphingolipidome” profile indicates that attention should be focused on specific acyl chains associated with obesity, per se, since total Cer and SM levels coupled with dyslipidemia and vitamin D deficiency can be confounding factors. Furthermore, exposure to hypoxia indicates a relationship between dyslipidemia, obesity, oxygen level and aerobic/anaerobic metabolism, thus, opening new research avenues in the role of sphingolipids.

FGF10 Enhances Peripheral Nerve Regeneration via the Preactivation of the PI3K/Akt Signaling-Mediated Antioxidant Response

The process of axonal regeneration after peripheral nerve injury (PNI) is slow and mostly incomplete. Previous studies have investigated the neuroprotective effects of fibroblast growth factor 10 (FGF10) against spinal cord injury and cerebral ischemia brain injury. However, the role of FGF10 in peripheral nerve regeneration remains unknown. In this study, we aimed to investigate the underlying therapeutic effects of FGF10 on nerve regeneration and functional recovery after PNI and to explore the associated mechanism. Our results showed that FGF10 administration promoted axonal regeneration and functional recovery after nerve damage. Moreover, exogenous FGF10 treatment also prevented SCs from excessive oxidative stress-induced apoptosis, which was probably related to the activation of phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt) signaling. The inhibition of the PI3K/Akt pathway by the specific inhibitor LY294002 partially reversed the therapeutic effects of FGF10 both in vivo and in vitro. Thus, from our perspective, FGF10 may be a promising therapeutic drug for repairing sciatic nerve damage through countering excessive oxidative stress-induced SC apoptosis.

Rhodiola crenulata attenuates apoptosis and mitochondrial energy metabolism disorder in rats with hypobaric hypoxia-induced brain injury by regulating the HIF-1α/microRNA 210/ISCU1/2(COX10) signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Rhodiola crenulata, a traditional Tibetan medicine, has shown promise in the treatment of hypobaric hypoxia (HH)-induced brain injury. However, the underlying mechanisms remain unclear. This study investigated the protective effects of R. crenulata aqueous extract (RCAE) on HH-induced brain injury in rats.

MATERIALS AND METHODS

An animal model of high-altitude hypoxic brain injury was established in SD rats using an animal decompression chamber for 24 h. Serum and hippocampus levels of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG), and lactate dehydrogenase (LDH) were then determined using commercial biochemical kits. Neuron morphology and vitality were also evaluated using H&E and Nissl staining, and TUNEL staining was used to examine apoptosis. Gene and protein expression of HIF-1α, microRNA 210, ISCU1/2, COX10, Apaf-1, cleaved Caspase-3, Caspase-3, Bax, Bcl-2, and Cyto-c were determined by western blot, immunohistochemical and qRT-PCR analysis.

RESULTS

RCAE administration attenuated HH-induced brain injury as evidenced by decreased levels of MDA, LDH, and GSSG, increased GSH and SOD, improvements in hippocampus histopathological changes, increased cell vitality and ATP level, and reduced apoptotic cell numbers. RCAE treatment also enhanced HIF-1α, ISCU1/2, COX10, and Bcl-2 protein expression, while dramatically inhibiting expression of Apaf-1, Bax, Cyto-c, and cleaved Caspase-3. Treatment also increased gene levels of HIF-1α, microRNA 210, ISCU1/2, and COX10, and decreased Caspase-3 gene production.

CONCLUSIONS

RCAE attenuated HH-induced brain injury by regulating apoptosis and mitochondrial energy metabolism via the HIF-1α/microRNA 210/ISCU1/2 (COX10) signaling pathway.

The Role of Salivary miR-134-3p and miR-15b-5p as Potential Non-invasive Predictors for Not Developing Acute Mountain Sickness

Background

Acute mountain sickness (AMS) is a crucial public health problem for high altitude travelers. Discriminating individuals who are not developing (AMS resistance, AMS−) from developing AMS (AMS susceptibility, AMS+) at baseline would be vital for disease prevention. Salivary microRNAs (miRNAs) have emerged as promising non-invasive biomarkers for various diseases. Thus, the aim of our study was to identify the potential roles of salivary miRNAs in identifying AMS− individuals pre-exposed to high altitude. Moreover, as hypoxia is the triggering factor for AMS, present study also explored the association between cerebral tissue oxygenation indices (TOI) and AMS development after exposed to high altitude, which was the complementary aim.

Methods

In this study, 124 healthy men were recruited, and were exposed at simulated high altitude of 4,500 m. Salivary miR-134-3p and miR-15b-5p were measured at baseline (200 m). AMS was diagnosed based on Lake Louise Scoring System at 4,500 m. The measurements of physiological parameters were recorded at both the altitudes.

Results

Salivary miR-134-3p and miR-15b-5p were significantly up-regulated in AMS− individuals as compared to the AMS+ (p < 0.05). In addition, the combination of these miRNAs generated a high power for discriminating the AMS− from AMS+ at baseline (AUC: 0.811, 95% CI: 0.731−0.876, p < 0.001). Moreover, the value of cerebral TOIs at 4,500 m were significantly higher in AMS− individuals, compared to AMS+ (p < 0.01).

Conclusion

Our study reveals for the first time that salivary miR-134-3p and miR-15b-5p can be used as non-invasive biomarkers for predicting AMS− individuals pre-exposed to high altitude.