Nrf2 activation in astrocytes contributes to spinal cord ischemic tolerance induced by hyperbaric oxygen preconditioning

The role of nitric oxide and hydrogen sulfide in spinal cord injury: an updated review

Medical gases play an important role in the pathophysiology of human diseases and have received extensive attention for their role in neuroprotection. Common pathological mechanisms of spinal cord injury include excitotoxicity, inflammation, cell death, glial scarring, blood-spinal cord barrier disruption, and ischemia/reperfusion injury. Nitric oxide and hydrogen sulfide are important gaseous signaling molecules in living organisms; their pathological role in spinal cord injury models has received more attention in recent years. This study reviews the possible mechanisms of spinal cord injury and the role of nitric oxide and hydrogen sulfide in spinal cord injury.

Hyperbaric Oxygen Reduces Oxidative Stress Impairment and DNA Damage and Simultaneously Increases HIF-1α in Ischemia-Reperfusion Acute Kidney Injury

The central exacerbating factor in the pathophysiology of ischemic-reperfusion acute kidney injury (AKI) is oxidative stress. Lipid peroxidation and DNA damage in ischemia are accompanied by the formation of 3-nitrotyrosine, a biomarker for oxidative damage. DNA double-strand breaks (DSBs) may also be a result of postischemic AKI. γH2AX(S139) histone has been identified as a potentially useful biomarker of DNA DSBs. On the other hand, hypoxia-inducible factor (HIF) is the "master switch" for hypoxic adaptation in cells and tissues. The aim of this research was to evaluate the influence of hyperbaric oxygen (HBO) preconditioning on antioxidant capacity estimated by FRAP (ferric reducing antioxidant power) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assay, as well as on oxidative stress parameter 3-nitrotyrosine, and to assess its effects on γH2AX(S139), HIF-1α, and nuclear factor-κB (NF-κB) expression, in an experimental model of postischemic AKI induced in spontaneously hypertensive rats. The animals were divided randomly into three experimental groups: sham-operated rats (SHAM, n = 6), rats with induced postischemic AKI (AKI, n = 6), and group exposed to HBO preconditioning before AKI induction (AKI + HBO, n = 6). A significant improvement in the estimated glomerular filtration rate, eGFR, in AKI + HBO group (p < 0.05 vs. AKI group) was accompanied with a significant increase in plasma antioxidant capacity estimated by FRAP (p < 0.05 vs. SHAM group) and a reduced immunohistochemical expression of 3-nitrotyrosine and γH2AX(S139). Also, HBO pretreatment significantly increased HIF-1α expression (p < 0.001 vs. AKI group), estimated by Western blot and immunohistochemical analysis in kidney tissue, and decreased immunohistochemical NF-κB renal expression (p < 0.01). Taking all of these results together, we may conclude that HBO preconditioning has beneficial effects on acute kidney injury induced in spontaneously hypertensive rats.

Oct4 reduction contributes to testicular injury of unilateral testicular torsion in mice model and apoptotic death of Sertoli cells through mediating CIP2A expression

This study explored the mechanism of ipsilateral testis injury after ipsilateral testicular torsion detorsion (T/D) and the potential testis-protective part of the octamer-binding transcription factor 4 (Oct4)-cancerous inhibitors of protein phosphatase 2A (CIP2A) axis in a T/D animal model and in ischemia-reperfusion (IR)-treated testicular Sertoli TM4 cells. Quantitative Polymerase chain reaction (PCR) and western blot (WB) confirmed the downregulation of both CIP2A and Oct4 expression in the testicular tissue from T/D mice compared with sham-operated mice. T/D model was then established in mice with upregulated Oct4 expression in the testis. Oct4 elevation restored CIP2A expression in testes after T/D treatment. Furthermore, we observed that an increase in Oct4 ameliorated the testicular damage caused by torsion in the testis. Biochemical analysis indicated that T/D treatment increased serum anti-sperm antibody levels, but reduced testosterone levels. Meanwhile, in testicular tissue, reactive oxygen species (ROS), malondialdehyde (MDA), and activity of testicular myeloperoxidase (MPO) enzymes were promoted, while glutathione peroxidase activity (GPx) was decreased by T/D injury. Notably, testicular Oct4 restoration partially counteracted the effect of T/D treatment on these biochemical indices. Hypoxia/reoxygenation (HR) treatment was applied to TM4 cells to mimic TT injury in vitro. A gain-of-function study showed that Oct4 overexpression partly counteracted the promoting role of HR in cell damage, apoptosis, and oxidative stress in TM4 cells. These observations provide novel insights into the possible biochemical mechanism underlying the mediation of the Oct4-CIP2A axis in T/D injury.

Nrf2 Activation: Involvement in Central Nervous System Traumatic Injuries. A Promising Therapeutic Target of Natural Compounds

Central nervous system (CNS) trauma, such as traumatic brain injury (TBI) and spinal cord injury (SCI), represents an increasingly important health burden in view of the preventability of most injuries and the complex and expensive medical care that they necessitate. These injuries are characterized by different signs of neurodegeneration, such as oxidative stress, mitochondrial dysfunction, and neuronal apoptosis. Cumulative evidence suggests that the transcriptional factor nuclear factor erythroid 2-related factor 2 (Nrf2) plays a crucial defensive role in regulating the antioxidant response. It has been demonstrated that several natural compounds are able to activate Nrf2, mediating its antioxidant response. Some of these compounds have been tested in experimental models of SCI and TBI, showing different neuroprotective properties. In this review, an overview of the preclinical studies that highlight the positive effects of natural bioactive compounds in SCI and TBI experimental models through the activation of the Nrf2 pathway has been provided. Interestingly, several natural compounds can activate Nrf2 through multiple pathways, inducing a strong antioxidant response against CNS trauma. Therefore, some of these compounds could represent promising therapeutic strategies for these pathological conditions.

Neuroprotective effect of the Nrf2/ARE/miRNA145-5p signaling pathway in the early phase of spinal cord injury

AIMS

Spinal cord injury (SCI) is a debilitating neurological condition often associated with chronic neuroinflammation and redox imbalance. Oxidative stress is one of the main hallmark of secondary injury of SCI which is tightly regulated by nuclear factor E2-related factor 2/antioxidant response element (Nrf2/ARE) signaling. In this study, we aimed at investigating the interplay between inflammation-related miRNAs and the Nrf2 pathway in animal model of SCI.

MATERIALS AND METHODS

The expression of selected four validated miRNA-target pairs (miRNA223-3p, miRNA155-5p, miRNA145-5p, and miRNA124-3p) was examined at different time points (6 h, 12 h, 1 day, 3 day and 7 day) after SCI. Further, using GFAP-specific kelch-like ECH-associated protein 1 deletion (Keap1-/-) and whole-body Nrf2-/- knockout mice, we investigated the potential interplay between each miRNA and the Keap1/Nrf2 signaling system.

KEY FINDINGS

The expression of all miRNAs except miRNA155-5p significantly increased 24 h after SCI and decreased after 7 days. Interestingly, Keap1-/- mice only showed significant increase in the miRNA145-5p after 24 h SCI compared to the WT group. In addition, Keap1-/- mice showed significant decrease in CXCL10/12 (CXCL12 increased in Nrf2-/- mice), and TNF-α, and an increase in Mn-SOD and NQO-1 (Mn-SOD and NQO-1 decreased in Nrf2-/- mice) compared to WT mice.

SIGNIFICANCE

Our results suggest that astrocytic hyperactivation of Nrf2 exert neuroprotective effects at least in part through the upregulation of miRNA145-5p, a negative regulator of astrocyte proliferation, and induction of ARE in early phase of SCI. Further studies are needed to investigate the potential interplay between Nrf2 and miRNA145-5p in neuroinflammatory condition.

Lithium promotes recovery after spinal cord injury

Lithium is associated with oxidative stress and apoptosis, but the mechanism by which lithium protects against spinal cord injury remains poorly understood. In this study, we found that intraperitoneal administration of lithium chloride (LiCl) in a rat model of spinal cord injury alleviated pathological spinal cord injury and inhibited expression of tumor necrosis factor α, interleukin-6, and interleukin 1 β. Lithium inhibited pyroptosis and reduced inflammation by inhibiting Caspase-1 expression, reducing the oxidative stress response, and inhibiting activation of the Nod-like receptor protein 3 inflammasome. We also investigated the neuroprotective effects of lithium intervention on oxygen/glucose-deprived PC12 cells. We found that lithium reduced inflammation, oxidative damage, apoptosis, and necrosis and up-regulated nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 in PC12 cells. All-trans retinoic acid, an Nrf2 inhibitor, reversed the effects of lithium. These results suggest that lithium exerts anti-inflammatory, anti-oxidant, and anti-pyroptotic effects through the Nrf2/heme oxygenase-1 pathway to promote recovery after spinal cord injury. This study was approved by the Animal Ethics Committee of Xi’an Jiaotong University (approval No. 2018-2053) on October 23, 2018.

Histological Findings After Aortic Cross-Clamping in Preclinical Animal Models

Spinal cord ischemic injury and paralysis are devastating complications after open surgical repair of thoracoabdominal aortic aneurysms. Preclinical models have been developed to simulate the clinical paradigm to better understand the neuropathophysiology and develop therapeutic treatment. Neuropathological findings in the preclinical models have not been comprehensively examined before. This systematic review studies the past 40 years of the histological findings after open surgical repair in preclinical models. Our main finding is that damage is predominantly in the grey matter of the spinal cord, although white matter damage in the spinal cord is also reported. Future research needs to examine the neuropathological findings in preclinical models after endovascular repair, a newer type of surgical repair used to treat aortic aneurysms.

A Pivotal Role of the Nrf2 Signaling Pathway in Spinal Cord Injury: A Prospective Therapeutics Study

The nuclear erythroid 2-related factor 2 (Nrf2) signaling pathway has a main role against oxidative stress and inflammation. Spinal Cord Injury (SCI) leads to the high secretion of inflammatory cytokines and reactive oxygen species, which disturbs nervous system function and regeneration. Several studies have indicated that the activation of the Nrf2 signaling pathway may be effective against inflammation after SCI. The experimental studies have indicated that many chemical and natural agents act as Nrf2 inducer, which inhibits the SCI progression. Thus, the finding of novel Nrf2- inducer anti-inflammatory agents may be a valuable approach in drug discovery. In the present review, we discussed the Nrf2 signal pathway and crosstalk with the NF-κB pathway and also the impact of this pathway on inflammation in animal models of SCI. Furthermore, we discussed the regulation of Nrf2 by several phytochemicals and drugs, as well as their effects on the SCI inhibition. Therefore, the current study presented a new hypothesis of the development of anti-inflammatory agents that mediate the Nrf2 signaling pathway for treating the SCI outcomes.

Identification of key microRNAs and the underlying molecular mechanism in spinal cord ischemia-reperfusion injury in rats

Spinal cord ischemia-reperfusion injury (SCII) is a pathological process with severe complications such as paraplegia and paralysis. Aberrant miRNA expression is involved in the development of SCII. Differences in the experimenters, filtering conditions, control selection, and sequencing platform may lead to different miRNA expression results. This study systematically analyzes the available SCII miRNA expression data to explore the key differently expressed miRNAs (DEmiRNAs) and the underlying molecular mechanism in SCII. A systematic bioinformatics analysis was performed on 23 representative rat SCII miRNA datasets from PubMed. The target genes of key DEmiRNAs were predicted on miRDB. The DAVID and TFactS databases were utilized for functional enrichment and transcription factor binding analyses. In this study, 19 key DEmiRNAs involved in SCII were identified, 9 of which were upregulated (miR-144-3p, miR-3568, miR-204, miR-30c, miR-34c-3p, miR-155-3p, miR-200b, miR-463, and miR-760-5p) and 10 downregulated (miR-28-5p, miR-21-5p, miR-702-3p, miR-291a-3p, miR-199a-3p, miR-352, miR-743b-3p, miR-125b-2-3p, miR-129-1-3p, and miR-136). KEGG enrichment analysis on the target genes of the upregulated DEmiRNAs revealed that the involved pathways were mainly the cGMP-PKG and cAMP signaling pathways. KEGG enrichment analysis on the target genes of the downregulated DEmiRNAs revealed that the involved pathways were mainly the Chemokine and MAPK signaling pathways. GO enrichment analysis indicated that the target genes of the upregulated DEmiRNAs were markedly enriched in biological processes such as brain development and the positive regulation of transcription from RNA polymerase II promoter. Target genes of the downregulated DEmiRNAs were mainly enriched in biological processes such as intracellular signal transduction and negative regulation of cell proliferation. According to the transcription factor analysis, the four transcription factors, including SP1, GLI1, GLI2, and FOXO3, had important regulatory effects on the target genes of the key DEmiRNAs. Among the upregulated DEmiRNAs, miR-3568 was especially interesting. While SCII causes severe neurological deficits of lower extremities, the anti-miRNA oligonucleotides (AMOs) of miR-3568 improve neurological function. Cleaved caspase-3 and Bax was markedly upregulated in SCII comparing to the sham group, and miR-3568 AMO reduced the upregulation. Bcl-2 expression levels showed a opposite trend as cleaved caspase-3. The expression of GATA6, GATA4, and RBPJ decreased after SCII and miR-3568 AMO attenuated this upregulation. In conclusion, 19 significant DEmiRNAs in the pathogenesis of SCII were identified, and the underlying molecular mechanisms were validated. The DEmiRNAs could serve as potential intervention targets for SCII. Moreover, inhibition of miR-3568 preserved hind limb function after SCII by reducing apoptosis, possibly through regulating GATA6, GATA4, and RBPJ in SCII.

Effect of Nrf2 signaling pathway on the improvement of intestinal epithelial barrier dysfunction by hyperbaric oxygen treatment after spinal cord injury

Disruption of the intestinal epithelial barrier following spinal cord injury (SCI) seriously affect long-term quality of life. Oxidative stress-induced epithelial cells' injury contributes to the epithelial barrier dysfunction. Hyperbaric oxygen (HBO) treatment has been proved to alleviate SCI. However, it is unclear whether or not HBO treatment affects intestinal barrier function following SCI. In this study, our purpose was to explore the impact of HBO treatment on intestinal epithelial barrier function and underlying mechanisms following SCI. An SCI model was established in rats, and the rats received HBO treatment. Intestinal injury, mucosal permeability, intercellular junction proteins, and oxidative stress indicators were evaluated in our study. We found that HBO treatment significantly alleviated intestinal histological damage, reduced mucosal permeability, and markedly prevented bacterial translocation. Furthermore, HBO treatment significantly increased the expression of Claudin-1 and E-cadherin, inhibited intestinal tissue oxidative stress as demonstrated by upregulation of superoxide dismutase and glutathione, and HBO downregulated malondialdehyde. Mechanically, we demonstrated that HBO treatment ameliorated intestinal oxidative stress possibly through upregulating nuclear factor E2-related factor 2 (Nrf2) and its downstream targets, Heme oxygenase-1(HO-1), NADH-quinone oxidoreductase-1(NQO-1), and glutamate cysteine ligase catalytic subunit (GCLC). These results suggested that HBO treatment triggered antioxidative effects against intestinal epithelial barrier dysfunction by promoting Nrf2 signaling pathway after SCI.

An Extra Breath of Fresh Air: Hyperbaric Oxygenation as a Stroke Therapeutic

Stroke serves as a life-threatening disease and continues to face many challenges in the development of safe and effective therapeutic options. The use of hyperbaric oxygen therapy (HBOT) demonstrates pre-clinical effectiveness for the treatment of acute ischemic stroke and reports reductions in oxidative stress, inflammation, and neural apoptosis. These pathophysiological benefits contribute to improved functional recovery. Current pre-clinical and clinical studies are testing the applications of HBOT for stroke neuroprotection, including its use as a preconditioning regimen. Mild oxidative stress may be able to prime the brain to tolerate full extensive oxidative stress that occurs during a stroke, and HBOT preconditioning has displayed efficacy in establishing such ischemic tolerance. In this review, evidence on the use of HBOT following an ischemic stroke is examined, and the potential for HBOT preconditioning as a neuroprotective strategy. Additionally, HBOT as a stem cell preconditioning is also discussed as a promising strategy, thus maximizing the use of HBOT for ischemic stroke.

The Treatment of Perioperative Spinal Cord Injury With Hyperbaric Oxygen Therapy: A Case Report

STUDY DESIGN

Case report (level IV evidence).

OBJECTIVE

To describe a potential novel application of hyperbaric oxygen therapy (HBOT) in the successful treatment of a postoperative spinal cord injury.

SUMMARY OF BACKGROUND DATA

A 68-year-old man presented with an acute spinal cord injury (ASIA impairment scale D), on the background of degenerative lower thoracic and lumbar canal stenosis. He underwent emergent decompression and instrumented fusion (T9-L5), with an uncomplicated intraoperative course and no electrophysiological changes. Immediate postoperative assessment demonstrated profound bilateral limb weakness (1/5 on the Medical Research Council [MRC] grading scale, ASIA impairment scale B), without radiological abnormality.

METHODS

Conventional medical management (hypertension, level 2 care) was instigated with the addition of Riluzole, with no effect after 30 hours. At 36 hours 100% oxygen at 2.8 atmospheres was applied for 90 minutes, and repeated after 8 hours, with a further three treatments over 48 hours.

RESULTS

The patient demonstrated near-immediate improvement in lower limb function to anti-gravity (MRC grading 3/5) after one treatment. Motor improvement continued over the following treatments, and after 2 weeks the patient was ambulatory. At 4 months, the patient demonstrated normal motor function with no sphincteric disturbance.

CONCLUSION

The application of HBOT contributed to the immediate and sustained improvement (ASIA B to ASIA E) in motor recovery after postoperative spinal cord injury. HBOT may represent a new avenue of therapy for spinal cord injury, and requires further prospective investigation.

LEVEL OF EVIDENCE

4.

Meta-analysis of mouse transcriptomic studies supports a context-dependent astrocyte reaction in acute CNS injury versus neurodegeneration

Background

Neuronal damage in acute CNS injuries and chronic neurodegenerative diseases is invariably accompanied by an astrocyte reaction in both mice and humans. However, whether and how the nature of the CNS insult—acute versus chronic—influences the astrocyte response, and whether astrocyte transcriptomic changes in these mouse models faithfully recapitulate the astrocyte reaction in human diseases remains to be elucidated. We hypothesized that astrocytes set off different transcriptomic programs in response to acute versus chronic insults, besides a shared “pan-injury” signature common to both types of conditions, and investigated the presence of these mouse astrocyte signatures in transcriptomic studies from human neurodegenerative diseases.

Methods

We performed a meta-analysis of 15 published astrocyte transcriptomic datasets from mouse models of acute injury (n = 6) and chronic neurodegeneration (n = 9) and identified pan-injury, acute, and chronic signatures, with both upregulated (UP) and downregulated (DOWN) genes. Next, we investigated these signatures in 7 transcriptomic datasets from various human neurodegenerative diseases.

Results

In mouse models, the number of UP/DOWN genes per signature was 64/21 for pan-injury and 109/79 for acute injury, whereas only 13/27 for chronic neurodegeneration. The pan-injury-UP signature was represented by the classic cytoskeletal hallmarks of astrocyte reaction (Gfap and Vim), plus extracellular matrix (i.e., Cd44, Lgals1, Lgals3, Timp1), and immune response (i.e., C3, Serping1, Fas, Stat1, Stat2, Stat3). The acute injury-UP signature was enriched in protein synthesis and degradation (both ubiquitin-proteasome and autophagy systems), intracellular trafficking, and anti-oxidant defense genes, whereas the acute injury-DOWN signature included genes that regulate chromatin structure and transcriptional activity, many of which are transcriptional repressors. The chronic neurodegeneration-UP signature was further enriched in astrocyte-secreted extracellular matrix proteins (Lama4, Cyr61, Thbs4), while the DOWN signature included relevant genes such as Agl (glycogenolysis), S1pr1 (immune modulation), and Sod2 (anti-oxidant). Only the pan-injury-UP mouse signature was clearly present in some human neurodegenerative transcriptomic datasets.

Conclusions

Acute and chronic CNS injuries lead to distinct astrocyte gene expression programs beyond their common astrocyte reaction signature. However, caution should be taken when extrapolating astrocyte transcriptomic findings from mouse models to human diseases.

MicroRNA-22-3p alleviates spinal cord ischemia/reperfusion injury by modulating M2 macrophage polarization via IRF5

Cell death after spinal cord ischemia/reperfusion (I/R) can occur through necrosis, apoptosis, and autophagy, resulting in changes to the immune environment. However, the molecular mechanism of this immune regulation is not clear. Accumulating evidence indicates that microRNAs (miRs) play a crucial role in the pathogenesis of spinal cord I/R injury. Here, we hypothesized miR-22-3p may be involved in spinal cord I/R injury by interacting with interferon regulatory factor (IRF) 5. Rat models of spinal cord I/R injury were established by 12-min occlusion of the aortic arch followed by 48-hr reperfusion, with L_4-6 segments of spinal cord tissues collected. MiR-22-3p agomir, a lentivirus-delivered siRNA specific for IRF5, or a lentivirus expressing wild-type IRF5 was injected intrathecally to rats with I/R injury to evaluate the effects of miR-22-3p and IRF5 on hindlimb motor function. Macrophages isolated from rats were treated with miR-22-3p mimic or siRNA specific for IRF5 to evaluate their effects on macrophage polarization. The levels of IL-1β and TNF-α in spinal cord tissues were detected by ELISA. miR-22-3p was down-regulated, whereas IRF5 was up-regulated in rat spinal cord tissues following I/R. IRF5 was a target gene of miR-22-3p and could be negatively regulated by miR-22-3p. Silencing IRF5 or over-expressing miR-22-3p relieved inflammation, elevated Tarlov score, and reduced the degree of severity of spinal cord I/R injury. Increased miR-22-3p facilitated M2 polarization of macrophages and inhibited inflammation in tissues by inhibiting IRF5, thereby attenuating spinal cord I/R injury. Taken together, these results demonstrate that increased miR-22-3p can inhibit the progression of spinal cord I/R injury by repressing IRF5 in macrophages, highlighting the discovery of a promising new target for spinal cord I/R injury treatment.

The role of astrocytes in oxidative stress of central nervous system: A mixed blessing

Central nervous system (CNS) maintains a high level of metabolism, which leads to the generation of large amounts of free radicals, and it is also one of the most vulnerable organs to oxidative stress. Emerging evidences have shown that, as the key homeostatic cells in CNS, astrocytes are deeply involved in multiple aspects of CNS function including oxidative stress regulation. Besides, the redox level in CNS can in turn affect astrocytes in morphology and function. The complex and multiple roles of astrocytes indicate that their correct performance is crucial for the normal functioning of the CNS, and its dysfunction may result in the occurrence and progression of various neurological disorders. To date, the influence of astrocytes in CNS oxidative stress is rarely reviewed. Therefore, in this review we sum up the roles of astrocytes in redox regulation and the corresponding mechanisms under both normal and different pathological conditions.

Changes in long non-coding RNA transcriptomic profiles after ischemia-reperfusion injury in rat spinal cord

With the aim of exploring expression profiles and biological functions of long non-coding RNA (lncRNA) and mRNAs after spinal cord ischemia-reperfusion injury (SCII), differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) in rat spinal cords were identified following SCII through high-throughput RNA sequencing. In total, 1,455 lncRNAs and 6,707 mRNAs were observed to be differentially expressed (—Fold Change— ≥ 2 and P < 0.05) after SCII, including 761 up-regulated and 694 down-regulated lncRNAs, 3,772 up-regulated and 2,935 down-regulated mRNAs. Gene ontology and KEGG pathway analysis showed that the DElncRNAs and DEmRNAs were implicated in many different biological processes and pathways. Further, lncRNA-mRNA co-expression networks were built to explore the potential roles of these DElncRNAs. Our results demonstrate genome-wide lncRNA and mRNA expression patterns in spinal cords after SCII, which may play vital roles in post-SCII pathophysiological processes. These findings are important for future functional research on the lncRNAs involved in SCII and might be critical for providing new insight into identification of potential targets for SCII therapy.

Combination Therapy With Hyperbaric Oxygen and Erythropoietin Inhibits Neuronal Apoptosis and Improves Recovery in Rats With Spinal Cord Injury

BACKGROUND

Apoptosis plays an important role in various diseases, including spinal cord injury (SCI). Hyperbaric oxygen (HBO) and erythropoietin (EPO) promote the recovery from SCI, but the relationship between apoptosis and the combination therapeutic effect is not completely clear.

OBJECTIVE

The purpose of this study was to investigate the effects of HBO and EPO on SCI and the mechanisms that underlie their therapeutic benefits.

DESIGN

The study was designed to explore the effects of HBO and EPO on SCI through a randomized controlled trial.

METHODS

Sixty young developing female Sprague-Dawley rats were randomly divided into groups of 12 rats receiving sham, SCI, HBO, EPO, or HBO plus EPO. The SCI model was modified with the Allen method to better control consistency. HBO was performed for 1 hour per day for a total of 21 days, and EPO was given once per week for a total of 3 weeks. Both methods were performed 2 hours after SCI. Locomotor function was evaluated with the 21-point Basso-Beattie-Bresnahan Locomotor Rating Scale, an inclined-plane test, and a footprint analysis. All genes were detected by Western blotting and immunohistochemistry. The level of cell apoptosis was determined by Hoechst staining.

RESULTS

The results showed that HBO and EPO promoted the recovery of locomotor function in the hind limbs of rats by inhibiting the apoptosis of neurons. During this period, the expression of B-cell lymphoma/leukemia 2 protein (Bcl-2) increased significantly, whereas the expression of Bcl-2-associated X protein (Bax) and cleaved caspase 3 decreased significantly, indicating the inhibition of apoptosis. Meanwhile, the expression of G protein-coupled receptor 17 decreased, and that of myelin basic protein increased, suggesting that there may be a potential connection between demyelination and neuronal apoptosis.

LIMITATIONS

The limitations of the study include deviations in the preparation of SCI models; lack of reverse validation of molecular mechanisms; absence of in vitro cell experiments; and only one time point after SCI was studied.

CONCLUSIONS

HBO and EPO treatments are beneficial for SCI, especially when the 2 therapies are combined.

Zinc-induced protective effect for testicular ischemia-reperfusion injury by promoting antioxidation via microRNA-101-3p/Nrf2 pathway

The present study was performed to determine the protective effect of Zinc on the rat testicular ischemia-reperfusion (I/R) injury and its mechanism. In vivo, the pathological changes and the apoptosis index were significantly relieved in the rats with Low-dose Zinc pretreatment, compared to the I/R group. After Low-dose Zinc treatment, the levels of tissue Malondialdehyde (MDA) were significantly decreased, while tissue antioxidant indices were significantly increased. Meanwhile, the level of NF-κB was significantly lower compared to I/R group, while the levels of Nrf2-dependent antioxidant enzymes were significantly higher in Low-dose Zinc+I/R group. In vitro, Low-dose Zinc markedly increased Leydig cell (TM3) cell viability, and relieved testicular oxidative damage via down-regulating ROS. A total of 22 differently expressed microRNAs were screened out using microRNA microarray in rat testicular tissue caused by I/R injury, especially showing that miR-101-3p was selected as the target miRNA. Furthermore, the levels of Nrf2 and NF-κB were apparently increased/decreased in TM3 cells treated with Hypoxic/Reoxygenation (H/R) after miR-101-3p mimics/inhibitor. In addition, H/R-induced testicular oxidative damage was recovered in TM3 administrated with miR-101-3p inhibitor and si-Nrf2. Therefore, this study provided a novel insight for investigating protective effect of Zinc on testicular I/R injury by promoting antioxidation via miR-101-3p/Nrf2.

Coenzyme Q10 suppresses oxidative stress and apoptosis via activating the Nrf-2/NQO-1 and NF-κB signaling pathway after spinal cord injury in rats

Spinal cord injury (SCI) is one of the most devastating diseases that may cause paralysis, disability and irreversible loss of functions, which ultimately lead to permanent disabilities and a decrease in patient life expectancy. Coenzyme Q10 (CoQ10) is a lipid-soluble vitamin-like benzoquinone compound that can exert antioxidant and anti-apoptotic functions in a variety of diseases. However, the antioxidant and anti-apoptotic effects of CoQ10 in the treatment of SCI are still unknown. Therefore, we designed experiments to measure the changes in antioxidant capacity (glutathione (GSH), superoxide dismutase (SOD) and the end product of lipid peroxidation (MDA)) and apoptosis products (Bax, Bcl-2 and Caspase-3) to evaluate the protective effects of CoQ10 on SCI and investigated whether CoQ10 exerts its functions through the Nrf-2/NQO-1 and NF-κB signaling pathway. Our results showed that CoQ10 treatment could significantly decrease the levels of oxidative products (MDA) and increase the activities of antioxidant enzymes (SOD and GSH) against oxidative stress, as well as decrease the levels of pro-apoptotic proteins (Bax and Caspase-3) and increase the levels of anti-apoptotic proteins (Bcl-2) against apoptosis after SCI. We also observed that CoQ10 exerted beneficial effects through the Nrf-2/NQO-1 and NF-κB signaling pathway. These findings suggested that CoQ10 had a protective effect by decreasing oxidative stress and apoptosis after SCI. Thus, our data may provide a new approach wherein CoQ10 may be considered as a potential effective therapeutic for the treatment of SCI.

The casual association of cervical spinal cord ischemia and axonal degeneration in second motor neuron following subarachnoid hemorrhage: Experimental study

AIM

Muscle abnormalities after spinal cord ischemia caused by subarachnoid hemorrhage (SAH) have not been explored for degenerative variations in the soma of second motor neurons of the spinal cord gray matter. This study aimed to investigate histopathological alterations in the gray matter and the role of peripheral nerves in SAH.

MATERIAL AND METHODS

Twenty-two rabbits were allocated in the control (Group I, n = 5), SHAM (Group II, n = 5), and research (Group III, n = 12) groups. Muscle weakness of the upper extremities innervated by radial nerves was evaluated at the initial day, and outcomes were recorded as control data. Re-measurements were done after injecting 0.5 ml of SF for SHAM and autolog artery blood inside craniocervical subarachnoid space for the study group. After 3 weeks, radial nerve roots, their ganglia, and segments of the spinal cord around C5-6 root entry zones were extracted bilaterally. Degenerated second motor neuron somas and the degenerated radial nerve motor axons at the intervertebral foramen were assessed.

RESULTS

The average degenerated soma intensity/mm³ at the C5-6 levels in the spinal cord was 2 ± 1/mm³, 13 ± 4/mm³, and 56 ± 10/mm³ for Groups I, II, and Group III. The average degenerated axon intensity of radial nerves was 3 ± 1/mm², 34 ± 9/mm², and 234 ± 78/mm² for Groups I, II, and III.

CONCLUSION

Gray matter ischemia in the spinal cord may lead to axonal deterioration on equal levels at the peripheral nerves with advanced SAH. Detected or undetected spinal SAH should be considered an important factor on the etiology of second motor neuron diseases.

The protective effect of epigallocatechin 3-gallate on mouse pancreatic islets via the Nrf2 pathway

PURPOSE

Epigallocatechin 3-gallate (EGCG), a green tea polyphenol, has been shown to have anti-oxidant and anti-inflammatory effects in vitro and in vivo. The aim of this study was to investigate the effects and mechanism of EGCG on isolated pancreatic islets as pre-conditioning for pancreatic islet transplantation.

METHODS

The pancreatic islets were divided into two groups: an islet culture medium group (control) and an islet culture medium with EGCG (100 µM) group. We investigated the islet viability, Nrf2 expression, reactive oxygen species (ROS) production, and heme oxygenase-1 (HO-1) mRNA. Five hundred islet equivalents after 12 h of culture for the EGCG 100 µM and control group were transplanted under the kidney capsule of streptozotocin-induced diabetic ICR mice.

RESULTS

The cell viability and insulin secretion ability in the EGCG group were preserved, and the nuclear translocation of Nrf2 was increased in the EGCG group (p < 0.01). While the HO-1 mRNA levels were also higher in the EGCG group than in the control group (p < 0.05), the ROS production was lower (p < 0.01). An in vivo functional assessment showed that the blood glucose level had decreased in the EGCG group after transplantation (p < 0.01).

CONCLUSION

EGCG protects the viability and function of islets by suppressing ROS production via the Nrf2 pathway.

CD28 Deficiency Ameliorates Thoracic Blast Exposure-Induced Oxidative Stress and Apoptosis in the Brain through the PI3K/Nrf2/Keap1 Signaling Pathway

Blast exposure is a worldwide public health concern, but most related research has been focused on direct injury. Thoracic blast exposure-induced neurotrauma is a type of indirect injuries where research is lacking. As CD28 stimulates T cell activation and survival and contributes to inflammation initiation, it may play a role in thoracic blast exposure-induced neurotrauma. However, it has not been investigated. To explore the effects of CD28 on thoracic blast exposure-induced brain injury and its potential molecular mechanisms, a mouse model of thoracic blast exposure-induced brain injury was established. Fifty C57BL/6 wild-type (WT) and fifty CD28 knockout (CD28^-/-) mice were randomly divided into five groups (one control group and four model groups), with ten mice (from each of the two models) for each group. Lung and brain tissue and serum samples were collected at 12 h, 24 h, 48 h, and 1 week after thoracic blast exposure. Histopathological changes were detected by hematoxylin-eosin staining. The expressions of inflammatory-related factors were detected by ELISA. Oxidative stress in the brain tissue was evaluated by determining the generation of reactive oxygen species (ROS) and the expressions of thioredoxin (TRX), malondialdehyde (MDA), SOD-1, and SOD-2. Apoptosis in the brain tissue was evaluated by TUNEL staining and the levels of Bax, Bcl-xL, Bad, Cytochrome C, and caspase-3. In addition, proteins of related pathways were also studied by western blotting and immunofluorescence. We found that CD28 deficiency significantly reduced thoracic blast exposure-induced histopathological changes and decreased the levels of inflammatory-related factors, including IL-1β, TNF-α, and S100β. In the brain tissue, CD28 deficiency also significantly attenuated thoracic blast exposure-induced generation of ROS and expressions of MDA, TRX, SOD-1, and SOD-2; lowered the number of apoptotic cells and the expression of Bax, cleaved caspase-3, Cytochrome C, and Bad; and maintained Bcl-xL expression. Additionally, CD28 deficiency significantly ameliorated thoracic blast exposure-induced increases of p-PI3K and Keap1 and the decrease of Nrf2 expression in the brain. Our results indicate that CD28 deficiency has a protective effect on thoracic blast exposure-induced brain injury that might be associated with the PI3K/Nrf2/Keap1 signaling pathway.

Polydatin attenuates spinal cord injury in rats by inhibiting oxidative stress and microglia apoptosis via Nrf2/HO-1 pathway

AIMS

Spinal cord injury (SCI) is one of the most devastating central lesions, resulting in serious locomotor deficit. Polydatin is a glucoside of resveratrol with proven anti-cardiovascular, anti-inflammatory and anti-oxidative properties. The main purpose of this study was to investigate whether polydatin could alleviate SCI in rats and explore the underlying mechanisms.

MATERIALS AND METHODS

SCI rats induced by a weight-drop device were treated with intraperitoneal injection of 20 or 40 mg/kg polydatin. Then the locomotor function of SCI rats was evaluated by the Basso, Beattie and Bresnahan locomotor rating scale, spinal cord edema was measured by the wet/dry weight method, oxidative stress markers were detected by commercial kits and cell apoptosis status was measured by TUNEL staining. In addition, reactive oxygen species (ROS) generation, lactate dehydrogenase (LDH) production and apoptosis status were detected in murine microglia BV2 cells treated with 100 ng/ml lipopolysaccharides (LPS) and 4.0 μM polydatin. The expression of apoptosis-related proteins involved in nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway was measured by western blot.

KEY FINDINGS

Our data showed that polydatin treatment improved locomotor performance of SCI rats, as well as reduced oxidative stress and inhibited apoptosis by enhancing Nrf2/HO-1 signaling. In addition, polydatin was found to up-regulate Nrf2 activity and the inhibitory effects of polydatin on oxidative stress and apoptosis in LPS-stimulated BV2 microglia was neutralized by silencing Nrf2 using specific siRNA.

SIGNIFICANCE

We demonstrate that polydatin may protect the spinal cord from SCI by suppression of oxidative stress and apoptosis via improving Nrf2/HO-1 signaling in microglia.

Z-Guggulsterone attenuates astrocytes-mediated neuroinflammation after ischemia by inhibiting toll-like receptor 4 pathway

Inflammatory damage plays a pivotal role in ischemic stroke pathogenesis and may represent one of the therapeutic targets. Z-Guggulsterone (Z-GS), an active component derived from myrrh, has been used to treat various diseases. The traditional uses suggest that myrrh is a good candidate for anti-inflammatory damage. This study was to investigate the anti-inflammatory and neuroprotective effects of Z-GS following cerebral ischemic injury, as well as the exact mechanisms behind them. Rat middle cerebral artery occlusion (MCAO) model and in vitro astrocytes oxygen-glucose deprivation (OGD) model were adopted to simulate ischemic stroke. Z-GS (30 or 60 mg/kg) was administered intraperitoneally immediately after reperfusion, while astrocytes were maintained in 30 or 60 μM Z-GS before OGD treatment. The results indicated that Z-GS significantly alleviated neurological deficits, infarct volume and histopathological damage in vivo, and increased the astrocytes viability in vitro. Moreover, the treatment of Z-GS inhibited the astrocytes activation and down-regulated the mRNA levels of pro-inflammatory cytokines. Furthermore, the activated TLR4-NF-κB signaling pathways induced by MCAO or OGD were significantly suppressed by Z-GS treatment, which was achieved via inhibiting the phosphorylation of JNK. Our results demonstrated that Z-GS exerted neuroprotective and anti-inflammatory properties through preventing activation of TLR4-mediated pathway in the activated astrocytes after ischemia injury. Therefore, Z-GS could be considered as a promising candidate for the treatment of ischemic stroke.

Dexmedetomidine attenuates spinal cord ischemia-reperfusion injury through both anti-inflammation and anti-apoptosis mechanisms in rabbits

Background

Dexmedetomidine (Dex) can improve neuronal viability and protect the spinal cord from ischemia–reperfusion (I/R) injury, but the underlying mechanisms are not fully understood. This study investigated the effects of dexmedetomidine on the toll-like receptor 4 (TLR4)-mediated nuclear factor κB (NF-κB) inflammatory system and caspase-3 dependent apoptosis induced by spinal cord ischemia–reperfusion injury.

Methods

Twenty-four rabbits were divided into three groups: I/R, Dex (10 µg/kg/h prior to ischemia until reperfusion), and Sham. Abdominal aortic occlusion was carried out for 30 min in the I/R and Dex groups. Hindlimb motor function was assessed using the Tarlov scoring system for gait evaluation. Motor neuron survival and apoptosis in the ventral grey matter were assessed by haematoxylin–eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labelling staining. The expression and localisation of ionised calcium-binding adaptor molecule 1, TLR4, NF-κB and caspase-3 were assessed by immunoreactivity analysis. The levels of interleukin 1β and tumour necrosis factor α were assessed using enzyme-linked immunosorbent assays.

Results

Perioperative treatment with dexmedetomidine was associated with a significant preservation of locomotor function following spinal cord ischemia–reperfusion injury with increased neuronal survival in the spinal cord compared to control. In addition, dexmedetomidine suppressed microglial activation, inhibited the TLR4-mediated NF-κB signalling pathway, and inhibited the caspase-3 dependent apoptosis.

Conclusions

Dexmedetomidine confers neuroprotection against spinal cord ischemia–reperfusion injury through suppression of spinal cord inflammation and neuronal apoptosis. A reduction in microglial activation and inhibition of both the TLR4-mediated NF-κB signalling pathway and caspase-3 dependent apoptosis are implicated.

A Dual Role for Hyperbaric Oxygen in Stroke Neuroprotection: Preconditioning of the Brain and Stem Cells

Stroke continues to be an extremely prevalent disease and poses a great challenge in developing safe and effective therapeutic options. Hyperbaric oxygen therapy (HBOT) has demonstrated significant pre-clinical effectiveness for the treatment of acute ischemic stroke, and limited potential in treating chronic neurological deficits. Reported benefits include reductions in oxidative stress, inflammation, neural apoptosis, and improved physiological metrics such as edema and oxygen perfusion, all of which contribute to improved functional recovery. This pre-clinical evidence has failed to translate into an effective evidence-based therapy, however, due in large part to significant inconsistencies in treatment protocols and design of clinical studies. While the medical community works to standardize clinical protocols in an effort to advance HBOT for acute stroke, pre-clinical investigations continue to probe novel applications of HBOT in an effort to optimize stroke neuroprotection. One such promising strategy is HBOT preconditioning. Based upon the premise of mild oxidative stress priming the brain for tolerating the full-blown oxidative stress inherent in stroke, HBOT preconditioning has displayed extensive efficacy. Here, we first review the pre-clinical and clinical evidence supporting HBOT delivery following ischemic stroke and then discuss the scientific basis for HBOT preconditioning as a neuroprotective strategy. Finally, we propose the innovative concept of stem cell preconditioning, in tandem with brain preconditioning, as a promising regenerative pathway for maximizing the application of HBOT for ischemic stroke treatment.

Neuroprotective effects of hyperbaric oxygen (HBO) therapy on neuronal death induced by sciatic nerve transection in rat

Background

Recent studies shows that hyperbaric oxygen (HBO) therapy exerts some protective effects against neural injuries. The purpose of this study was to determine the neuroprotective effects of HBO following sciatic nerve transection (SNT).

Methods

Rats were randomly divided into five groups (n = 14 per group): Sham-operated (SH) group, SH + HBO group, SNT group, and SNT + pre- and SNT + post-HBO groups (100% oxygen at 2.0 atm absolute, 60 min/day for five consecutive days beginning on 1 day before and immediately after nerve transaction, respectively). Spinal cord segments of the sciatic nerve and related dorsal root ganglions (DRGs) were removed 4 weeks after nerve transection for biochemical assessment of malodialdehyde (MDA) levels in spinal cord, biochemical assessment of superoxide dismutase (SOD) and catalse (CAT) activities in spinal cord, immunohistochemistry of caspase-3, cyclooxigenase-2 (COX-2), S100beta (S100ß), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) in spinal cord and DRG.

Results

The results revealed that MDA levels were significantly decreased in the SNT + pre-HBO group, while SOD and CAT activities were significantly increased in SNT + pre- and SNT + post-HBO treated rats. Attenuated caspase-3 and COX-2 expression, and TUNEL reaction could be significantly detected in the HBO-treated rats after nerve transection. Also, HBO significantly increased S100ß expression.

Conclusions

Based on these results, we can conclude that pre- and post-HBO therapy had neuroprotective effects against sciatic nerve transection-induced degeneration.

Mitochondria As Sources and Targets of Methane

This review summarizes the current knowledge on the role of mitochondria in the context of hypoxic cell biology, while providing evidence of how these mechanisms are modulated by methane (CH₄). Recent studies have unambiguously confirmed CH₄ bioactivity in various in vitro and in vivo experimental models and established the possibility that CH₄ can affect many aspects of mitochondrial physiology. To date, no specific binding of CH₄ to any enzymes or receptors have been reported, and it is probable that many of its effects are related to physico-chemical properties of the non-polar molecule. (i) Mitochondria themselves can be sources of endogenous CH₄ generation under oxido-reductive stress conditions; chemical inhibition of the mitochondrial electron transport chain with site-specific inhibitors leads to increased formation of CH₄ in eukaryote cells, in plants, and in animals. (ii) Conventionally believed as physiologically inert, studies cited in this review demonstrate that exogenous CH₄ modulates key events of inflammation. The anti-apoptotic effects of exogenously administered CH₄ are also recognized, and these properties also suggest that CH₄-mediated intracellular signaling is closely associated with mitochondria. (iii) Mitochondrial substrate oxidation is coupled with the reduction of molecular oxygen, thus providing energy for cellular metabolism. Interestingly, recent in vivo studies have shown improved basal respiration and modulated mitochondrial oxidative phosphorylation by exogenous CH₄. Overall, these data suggest that CH₄ liberation and effectiveness in eukaryotes are both linked to hypoxic events and redox regulation and support the notion that CH₄ has therapeutic roles in mammalian pathophysiologies.

Hyperbaric oxygen therapy of spinal cord injury

Spinal cord injury (SCI) is a complex disease process that involves both primary and secondary mechanisms of injury and can leave patients with devastating functional impairment as well as psychological debilitation. While no curative treatment is available for spinal cord injury, current therapeutic approaches focus on reducing the secondary injury that follows SCI. Hyperbaric oxygen (HBO) therapy has shown promising neuroprotective effects in several experimental studies, but the limited number of clinical reports have shown mixed findings. This review will provide an overview of the potential mechanisms by which HBO therapy may exert neuroprotection, provide a summary of the clinical application of HBO therapy in patients with SCI, and discuss avenues for future studies.

Methane ameliorates spinal cord ischemia-reperfusion injury in rats: Antioxidant, anti-inflammatory and anti-apoptotic activity mediated by Nrf2 activation

Methane is reported to have antioxidant, anti-inflammatory and anti-apoptotic properties. We investigated the potential neuroprotective effects of methane-rich saline (MS) on spinal cord ischemia-reperfusion injury and determined that its therapeutic benefits are associated with the activation of nuclear factor erythroid 2-related factor 2 (Nrf2). Rats received 9min of spinal cord ischemia induced by occlusion of the descending thoracic aorta plus systemic hypotension followed by a single MS treatment (10ml/kg, ip) and 72h reperfusion. MS treatment attenuated motor sensory deficits and produced high concentrations of methane in spinal cords during reperfusion, which increased Nrf2 expression and transcriptional activity in neurons, microglia and astrocytes in the ventral, intermediate and dorsal gray matter of lumbar segments. Heme oxygenase-1, superoxide dismutase, catalase and glutathione were upregulated; and glutathione disulfide, superoxide, hydrogen peroxide, malondialdehyde, 8-hydroxy-2-deoxyguanosine and 3-nitrotyrosine were downregulated in MS-treated spinal cords. MS treatment reduced neuronal apoptosis in gray matter zones, which was consistent with the suppression of cytochrome c release to the cytosol from the mitochondria and the activation of caspase-9 and -3. Throughout the gray matter, the activation of microglia and astrocytes was inhibited; the nuclear accumulation of phosphorylated nuclear factor-kappa B p65 was reduced; and tumor necrosis factor α, interleukin 1β, chemokine (C-X-C motif) ligand 1, intercellular adhesion molecule 1 and myeloperoxidase were decreased. MS treatment attenuated blood-spinal cord barrier dysfunction by preventing the expression and activity of matrix metallopeptidase-9 and disrupting tight junction proteins. Consecutive intrathecal injection of specific siRNAs targeting Nrf2 at 24-h intervals 3 days before ischemia reduced the beneficial effects of MS. Our data indicate that MS treatment prevents IR-induced spinal cord damage via antioxidant, anti-inflammatory and anti-apoptotic activities that involve the activation of Nrf2 signaling. Thus, methane may serve as a novel promising therapeutic agent for treating ischemic spinal cord injury.

Nrf2-dysregulation correlates with reduced synthesis and low glutathione levels in experimental autoimmune encephalomyelitis

This study investigates the possible mechanism(s) underlying glutathione (GSH) deficiency in the mouse spinal cord during the course of myelin oligodendrocyte glycoprotein35-55 peptide-induced experimental autoimmune encephalomyelitis (EAE), a commonly used animal model of multiple sclerosis. Using the classical enzymatic recycling method and a newly developed immunodot assay, we first demonstrated that total GSH levels (i.e. free GSH plus all its adducts) are reduced in EAE, suggesting an impaired synthesis. The decline in the levels of this essential antioxidant tripeptide in EAE coincides temporally and in magnitude with a reduction in the amount of γ-glutamylcysteine ligase, the rate-limiting enzyme in GSH synthesis. Other enzymes involved in GSH biosynthesis, whose genes also contain antioxidant-response elements, including glutathione synthetase, cystine/glutamate antiporter, and γ-glutamyl transpeptidase (γ-GT) are diminished in EAE as well. Low levels of γ-glutamylcysteine ligase, glutathione synthetase, and γ-GT are the consequence of reduced mRNA expression, which correlates with diminished expression of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in both the cytosol and nucleus. Interestingly, the low Nrf2 expression does not seem to be caused by increased degradation via Kelch-like ECH-associated protein 1-dependent or Kelch-like ECH-associated protein 1-independent mechanisms (such as glycogen synthetase kinase-3β activation), or by reduced levels of Nrf2 mRNA. This suggests that translation of this important transcription factor and/or other still unidentified post-translational processes are altered in EAE. These novel findings are central toward understanding how critical antioxidant and protective responses are lost in inflammatory demyelinating disorders.

Hyperbaric oxygen preconditioning protects the lung against acute pancreatitis induced injury via attenuating inflammation and oxidative stress in a nitric oxide dependent manner

This study aimed to investigate the protective effects of hyperbaric oxygen preconditioning (HBO-PC) on acute pancreatitis AP associated acute lung injury (ALI) and the potential mechanisms. Rats were randomly divided into sham group, AP group, HBO-PC + AP group and HBO-PC + L-NAME group. Rats in HBO-PC + AP group received HBO-PC once daily for 3 days, and AP was introduced 24 h after last HBO-PC. In HBO-PC + L-NAME group, L-NAME (40 mg/kg) was intraperitoneally injected before each HBO-PC. At 24 h after AP, the blood lipase and amylase activities were measured; the lung and pancreas were harvested for pathological examination; the bronchoalveolar lavage fluid was collected for the detection of lactate dehydrogenase (LDH) and proteins; inflammatory factors, superoxide dismutase (SOD) activity and malonaldehyde content were measured in the lung and blood; the Nrf2, SOD-1 and haem oxygenase-1 (HO-1) protein expression was measured in the lung. The lung nitric oxide (NO) and NO synthase activity increased significantly after HBO-PC. HBO-PC was able to reduce blood lipase and amylase activities, improve lung and pancreatic pathology, decrease LDH and proteins in BALF, inhibit the production of inflammatory factors, reduce malonaldehyde content and increase SOD activity in the lung and blood as well as increase protein expression of Nrf2, SOD-1 and HO-1 in the lung. However, L-NAME before HBO-PC significantly attenuated protective effects of HBO-PC. HBO-PC is able to protect the lung against AP induced injury by attenuating inflammation and oxidative stress in the lung via a NO dependent manner.

Current and emerging treatment options for spinal cord ischemia

Spinal cord infarction (SCI) is a rare but disabling disorder caused by a wide spectrum of conditions. Given the lack of randomized-controlled trials, contemporary treatment concepts are adapted from guidelines for cerebral ischemia, atherosclerotic vascular disease, and acute traumatic spinal cord injury. In addition, patients with SCI are at risk for several potentially life-threatening but preventable systemic and neurologic complications. Notably, there is emerging evidence from preclinical studies for the use of neuroprotection in acute ischemic injury of the spinal cord. In this review, we discuss the current state of the art for the therapy and prevention of SCI and highlight potential emerging treatment concepts awaiting translational adoption.

Hyperbaric oxygen preconditioning ameliorates hypoxia-ischemia brain damage by activating Nrf2 expression in vivo and in vitro

The present study aimed to investigate whether hyperbaric oxygen preconditioning (HBO-PC) could ameliorate hypoxia-ischemia brain damage (HIBD) by an increase of Nrf2 expression. P7 Sprague-Dawley rats (aged 7 d, n = 195) were used in two in vivo experiments, including BO-PC exposure experiments in non-HIBD models and treatment experiments in HIBD models. 2,3,5-triphenyltetrazolium chloride (TTC) staining, Nissl Staining, and TUNEL staining were performed. And expressions of Nrf2, HO-1, and GSTs were measured. For in vitro studies, oxygen-glucose deprivation cells were established. Morphological and apoptotic staining and gene silencing of Nrf2 by siRNA transfection were investigated. For exposure experiments, HBO-PC for longer time increased the expression of Nrf2 significantly. And for treatment experiments, HBO-PC treatment significantly decreased infarction area, lessened neuronal injury, reduced apoptosis, and increased both the expression of Nrf2 and activities of its downstream proteins. Cytology tests confirmed effects of HBO-PC treatments. Besides, Nrf2 siRNA significantly reduced protective effects of HBO-PC. These observations demonstrated that an up-regulation of Nrf2 by HBO-PC might play an important role in the generation of tolerance against HIBD.

Nrf2 activation as target to implement therapeutic treatments

A chronic increase of oxidative stress is typical of serious pathologies such as myocardial infarction, stroke, chronic limb ischemia, chronic obstructive pulmonary disease (COPD), type II-diabetes, age-related macular degeneration leads to an epic increase of morbidity and mortality in all countries of the world. The initial inflammation followed by an excessive release of reactive oxygen species (ROS) implies a diffused cellular injury that needs to be corrected by an inducible expression of the innate detoxifying and antioxidant system. The transcription factor Nrf2, when properly activated, is able to restore a redox homeostasis and possibly improve human health.

Hyperbaric Oxygen Preconditioning Attenuates Myocardium Ischemia-Reperfusion Injury Through Upregulation of Heme Oxygenase 1 Expression: PI3K/Akt/Nrf2 Pathway Involved

BACKGROUND

With the rise of the burden of ischemic heart disease, both clinical and economic evidence show a desperate need to protect the heart against myocardium ischemia-reperfusion injury-related complications following cardiac surgery or percutaneous coronary intervention. However, there is no effective intervention for myocardium ischemia-reperfusion injury as yet.

METHODS

We pretreated mice with 4 daily 2.0 absolute atmosphere (ATA) hyperbaric oxygen, then observed its effects on heart function parameters and infarct size following in situ ischemia-reperfusion. Multiple oxidative and inflammation products were measured in the myocardium. Next, we investigated the expression of heme oxygenase 1 (HO-1), phosphatidylinositol 3-kinase (PI3K)/serine/threonine protein kinase (Akt) pathway, and NF-E2-related factor 2 (Nrf2) in the presence of myocardium ischemia-reperfusion injury, hyperbaric oxygen preconditioning, and their inhibitors and their effects on heart function parameters.

RESULTS

Hyperbaric oxygen preconditioning ameliorated the cardiac function and histological alterations induced by myocardium ischemia-reperfusion injury, decreased oxidative products and proinflammatory cytokine. Hyperbaric oxygen preconditioning increased expression of HO-1, which was suppressed by PI3K inhibitor LY294002, Nrf2 knockout, and Akt inhibitor triciribine. The expression of Nrf2 was enhanced by hyperbaric oxygen preconditioning, but decreased by LY294002 and triciribine. The Akt was also activated by hyperbaric oxygen preconditioning but suppressed by LY294002. The hemodynamic assays showed that cardiac function was suppressed by LY294002, Nrf2 knockout, and triciribine.

CONCLUSION

These data present a novel signaling mechanism by which hyperbaric oxygen preconditioning protects myocardium ischemia-reperfusion injury via PI3K/Akt/Nrf2-dependent antioxidant defensive system.