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

Targeting the sigma-1 receptor with pridopidine induces functional neurorestoration in spinal cord ischemia-reperfusion injury

Spinal cord ischemia reperfusion injury (IRI) occurs with an incidence of 1-32%, often leading to paraplegia with limited prevention options. Pridopidine (Prdpn), a highly selective sigma-1 receptor (Sig-1R) agonist, serves as a protein chaperone that is engaged in neuroplasticity and cellular defense. This research aimed to assess the neuroprotective properties of Prdpn in spinal cord IRI in rats and investigate the underlying mechanisms. Forty male Wistar albino rats were randomly allocated into 4 groups: control, sham, IRI, and IRI + Prdpn. Tarlov's test was used to examine behavioral performance, as well as withdrawal from agonizing stimuli and the placing/stepping reflex (SPR). Biochemical markers, including spinal malondialdehyde (MDA), AOPP, antioxidant GPX, TNF-α and IL-1β, and apoptotic caspase-3, were measured, along with BDNF, GDNF, and Sig-1R gene expression. Histopathological changes in spinal cord tissue were also evaluated. Spinal cord IRI significantly caused neurological deficits, evidenced by lower scores in Tarlov's test, withdrawal from agonizing stimuli, and SPR. Biochemically, spinal cord IRI led to decreased GPX and increased MDA, AOPP, TNF-α, IL-1β, caspase-3, and GDNF levels, along with downregulated BDNF and Sig-1R gene expression. Histopathologically, spinal cord IRI resulted in greater spinal neuronal degeneration, apoptosis, and demyelination. However, treatment with Prdpn significantly improved behavioral outcomes and partially reversed the biochemical and histopathological alterations. Prdpn improved spinal cord IRI-induced behavioral deficits through its antioxidant, anti-inflammatory, anti-apoptotic, and neurotrophic properties. It suggests promise as a potential treatment option to stop spinal cord IRI.

Blocking of Tim-3 Ameliorates Spinal Cord Ischemia-Reperfusion Injury Through Inhibiting Neuroinflammation and Promoting M1-to-M2 Phenotypic Polarization of Microglia

BACKGROUND

Blocking of Tim-3 exerts therapeutic effects in a series of ischemia-reperfusion injury (IRI).

METHODS

In this work, a cross-clamped aortic arch was conducted to establish SCIRI rat model. Besides, rat spinal microglia was subjected to OGD/R to mimic I/R-like conditions in vitro. The in vivo and in vitro therapeutic effects of Tim-3 antibody in SCIRI were investigated from these aspects: neuronal apoptosis, neuroinflammation, microglia activation, and polarization.

RESULTS

It was verified that Tim-3 was highly expressed in spinal cord tissues of SCIRI rats and blocking of Tim-3 attenuated SCIRI-induced pathological injury, neuronal apoptosis, neuroinflammation, and microglia activation (M1 polarization). In addition, it was verified that Tim-3 was highly expressed in OGD/R-treated rat spinal microglia and blocking of Tim-3 attenuated OGD/R-induced inflammation and spinal microglia activation (M1 polarization).

CONCLUSIONS

Tim-3 antibody can exert therapeutic effects in SCIRI through inhibiting neuroinflammation and promoting microglia polarization from M1 to M2 phenotype.

Methane-rich saline ameliorates depressive-like behaviors during chronic unpredictable mild stress (CUMS)

Depression, considered the most prevalent neuropsychiatric disorder, is multifactorial and complex. Oxidative stress and inflammation significantly contribute to its etiology. Conversely, methane, a novel therapeutic gas, has demonstrated efficacy in enhancing tissue resilience against ischemic injuries and inflammation. In this study, we investigated the effect of methane-rich saline (MRS) on depression using the chronic unpredictable mild stress (CUMS) model. Depressed rats received MRS treatment, and depression-like behaviors and cognitive function were assessed through sucrose preference, open field, forced swimming, and Morris water maze tests. Additionally, we measured serum corticosterone levels, antioxidant enzyme activity, hippocampal malondialdehyde (MDA), and TNFα levels, and investigated histological changes in the hippocampus. Our findings revealed that MRS significantly ameliorated Depressive-like behaviors and cognitive impairment. Furthermore, MRS administration regulated serum corticosterone levels and also MRS reduced hippocampal lipid peroxidation, TNFα, and hippocampus tissue damage. MRS likely exerts its effects by reducing oxidative stress and inflammatory factors and modulating the function of the hypothalamus-pituitary-adrenal (HPA) axis. These results demonstrate the protective effects of MRS on the hippocampus in CUMS animals.

Nrf2 affects DNA damage repair and cell apoptosis through regulating HR and the intrinsic Caspase-dependent apoptosis pathway in TK6 cells exposed to hydroquinone

Hydroquinone (HQ) is one of benzene metabolites that can cause oxidative stress damage and Homologous recombination repair (HR). A good deal of reactive oxygen species (ROS) generated by oxidative stress can trigger apoptotic signaling pathways. The nuclear factor erythroid 2-related factor 2 (Nrf2) can regulate the cell response to oxidative stress damage. The aim of this study was to explore whether Nrf2 participate in HQ-induced apoptosis and its mechanism. The findings displayed that HQ triggered HR, promoted Nrf2 transfer into the cell nucleus and induced cell apoptosis, while Nrf2 deficient elevated cell apoptosis, attenuated the expression of PARP1 and RAD51. We also observed that Nrf2 deficient triggered Caspase-9. Thus, we speculated that Nrf2 might participate in HQ-induced cell apoptosis through Caspase-9 dependent pathways. Meanwhile, Nrf2 participated in HQ-induced DNA damage repair by regulating the level of PARP1 and RAD51.

Protective effects of curcumin against spinal cord injury

Background

In parallel with population aging, the prevalence of neurological and neurodegenerative diseases has been dramatically increasing over the past few decades. Neurodegenerative diseases reduce the quality of life of patients and impose a high cost on the health system. These slowly progressive diseases can cause functional, perceptual, and behavioral deficits in patients. Therefore, neurodegenerative impairments have always been an interesting subject for scientists and clinicians. One of these diseases is spinal cord injury (SCI). SCI can lead to irreversible damage and is classified into two main subtypes: traumatic and non-traumatic, each with very different pathophysiological features.

Aims

This review aims to gather relevant information about the beneficial effects of curcumin (Cur), with specific emphasis on its anti-inflammatory properties towards spinal cord injury (SCI) patients.

Materials & Methods

The review collates data from extensive in-vitro, in-vivo, and clinical trials documenting the effects of CUR on SCI. It examines the modulation of pathophysiological pathways and regulation of the inflammatory cascades after CUR administration.

Results

Various pathophysiological processes involving the nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor kappa B (NF-kB), and transforming growth factor beta (TGF-β) signaling pathways have been suggested to exacerbate damages resulting from SCI. CUR administration showed to modulate these signaling pathways which lead to attenuation of SCI complications.

Discussion

Anti-inflammatory compounds, particularly CUR, can modulate these pathophysiological pathways and regulate the inflammatory cascades. CUR, a well-known natural product with significant anti-inflammatory effects, has been extensively documented in experimental and clinical trials.

Conclusion

Curcumin's potential to alter key steps in the Nrf2, NF-kB, and TGF-β signaling pathways suggests that it may play a role in attenuating SCI complications.

Angiotensin II Type 1 receptor blockade attenuates the neuropathological changes in the spinal cords of diabetic rats with modulation of nuclear factor erythroid 2-related factor 2/ heme oxygenase 1 system

Peripheral and central neuropathies frequently complicate worldwide diabetes. Compared to peripheral neuropathy, central neuropathy didn`t gain a major research interest. Angiotensin II is reported to be involved in diabetic neuropathic pain but its role in the central pathological changes in the spinal cord is not clear. Here, we study the role of Losartan; an Angiotensin II receptor 1 (AT1) antagonist in suppression of the diabetes-induced changes in the spinal cord. Three groups of rats were applied; a negative control group, a streptozotocin (STZ) diabetic group, and a group receiving STZ and Losartan. After two months, the pathological alteration in the spinal cord was investigated, and an immunohistochemical study was performed for neuronal, astrocytic, and microglial markers; nuclear protein (NeuN), Glial fibrillary acidic protein (GFAP), and Ionized calcium-binding adaptor molecule 1 (Iba1), respectively, and for an apoptosis marker; caspase-3, and the inflammatory marker; nuclear factor kappa B (NF-kB) signaling, heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2); physiological antioxidant system. The results showed that Losartan caused recovery of spinal cord changes, by inhibiting the microglial and astrocytic activation, suppressing neuronal apoptosis and NF-kB expression with activation of Nrf2/HO-1 (P<0.0005). It is suggested, herein, that Losartan can suppress diabetes-induced glial activation, inflammation, neuronal apoptosis, and oxidative stress in the spinal cord; the mechanisms that may underlie the role of AT1 antagonism in suppressing diabetic neuropathic pain.

Mechanism of Fat Mass and Obesity-Related Gene-Mediated Heme Oxygenase-1 m6A Modification in the Recovery of Neurological Function in Mice with Spinal Cord Injury

OBJECTIVES

This study examined the mechanism of fat mass and obesity-related gene (FTO)-mediated heme oxygenase-1 (HO-1) m6A modification facilitating neurological recovery in spinal cord injury (SCI) mice. FTO/HO-1 was identified as a key regulator of SCI as well as a potential target for treatment of SCI.

METHODS

An SCI mouse was treated with pcDNA3.1-FTO/pcDNA3.1-NC/Dac51. An oxygen/glucose deprivation (OGD) cell model simulated SCI, with cells treated with pcDNA3.1-FTO/si-HO-1/Dac51. Motor function and neurobehavioral evaluation were assessed using the Basso, Beattie, and Bresnahan (BBB) scale and modified neurological severity score (mNSS). Spinal cord pathology and neuronal apoptosis were assessed. Further, FTO/HO-1 mRNA and protein levels, HO-1 mRNA stability, the interaction of YTHDF2 with HO-1 mRNA, neuronal viability/apoptosis, and HO-1 m6A modification were evaluated.

RESULTS

Spinal cord injury mice exhibited reduced BBB, elevated mNSS scores, disorganized spinal cord cells, scattered nuclei, and severe nucleus pyknosis. pcDNA3.1-FTO elevated FTO mRNA, protein expression, and BBB score; reduced the mNSS score of SCI mice; decreased neuronal apoptosis; improved the cell arrangement; and improved nucleus pyknosis in spinal cord tissues. OGD decreased FTO expression. FTO upregulation ameliorated OGD-induced neuronal apoptosis. pcDNA3.1-FTO reduced HO-1 mRNA and protein and HO-1 m6A modification, while increasing HO-1 mRNA stability and FTO in OGD-treated cells. FTO upregulated HO-1 by modulating m6A modification. HO-1 downregulation attenuated the effect of FTO. pcDNA3.1-FTO/Dac51 increased the HO-1 m6A level in mouse spinal cord tissue homogenate, reduced BBB, boosted mNSS scores of SCI mice, aggravated nucleus pyknosis, and increased neuronal apoptosis in spinal cord tissues, confirming that FTO mediated HO-1 m6A modification facilitated neurological recovery in SCI mice.

CONCLUSION

The fat mass and obesity-related gene modulates HO-1 mRNA stability by regulating m6A modification levels, thereby influencing HO-1 expression and promoting neurological recovery in SCI mice.

GPAT3 deficiency attenuates corticosterone-caused hepatic steatosis and oxidative stress through GSK3β/Nrf2 signals

The development of nonalcoholic fatty liver disease (NAFLD) may worsen due to chronic stress or prolonged use of glucocorticoids. Glycerol-3-phosphate acyltransferase 3 (GPAT3), has a function in obesity and serves as a key rate-limiting enzyme that regulates triglyceride synthesis. However, the precise impact of GPAT3 on corticosterone (CORT)-induced NAFLD and its underlying molecular mechanism remain unclear. For our in vivo experiments, we utilized male and female mice that were GPAT3-/- and wild type (WT) and treated them with CORT for a duration of 4 weeks. In our in vitro experiments, we transfected AML12 cells with GPAT3 siRNA and subsequently treated them with CORT. Under CORT-treated conditions, the absence of GPAT3 greatly improved obesity and hepatic steatosis while enhancing the expression of genes involved in fatty acid oxidation, as evidenced by our findings. In addition, the deletion of GPAT3 significantly inhibited the production of reactive oxygen species (ROS), increased the expression of antioxidant genes, and recovered the mitochondrial membrane potential in AML12 cells treated with CORT. In terms of mechanism, the absence of GPAT3 encouraged the activation of the glycogen synthase kinase 3β (GSK3β)/nuclear factor-erythroid 2 related factor 2 (Nrf2) pathway, which served as a defense mechanism against liver fat accumulation and oxidative stress. Furthermore, GPAT3 expression was directly controlled at the transcriptional level by the glucocorticoid receptor (GR). Collectively, our findings suggest that GPAT3 deletion significantly alleviated hepatic steatosis and oxidative stress through promoting GSK3β/Nrf2 signaling pathways.

Flavonoids and ischemic stroke-induced neuroinflammation: Focus on the glial cells

Ischemic stroke is one of the most cases worldwide, with high rate of morbidity and mortality. In the pathological process of ischemic stroke, neuroinflammation is an essential process that defines the functional prognosis. After stroke onset, microglia, astrocytes and the infiltrating immune cells contribute to a complicated neuroinflammation cascade and play the complicated roles in the pathophysiological variations of ischemic stroke. Both microglia and astrocytes undergo both morphological and functional changes, thereby deeply participate in the neuronal inflammation via releasing pro-inflammatory or anti-inflammatory factors. Flavonoids are plant-specific secondary metabolites and can protect against cerebral ischemia injury via modulating the inflammatory responses. For instances, quercetin can inhibit the expression and release of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, IL-6 and IL-1β, in the cerebral nervous system (CNS). Apigenin and rutin can promote the polarization of microglia to anti-inflammatory genotype and then inhibit neuroinflammation. In this review, we focused on the dual roles of activated microglia and reactive astrocyte in the neuroinflammation following ischemic stroke and discussed the anti-neuroinflammation of some flavonoids. Importantly, we aimed to reveal the new strategies for alleviating the cerebral ischemic stroke.

Diallyl trisulfide improves spinal cord ischemia-reperfusion injury damage by activating AMPK to stabilize mitochondrial function

BACKGROUND

Spinal cord ischemia-reperfusion injury (SCII) is a catastrophic event, which can cause paraplegia in severe cases. In the reperfusion stage, oxidative stress was up-regulated, which aggravated the injury and apoptosis of neurons. As the main active ingredient of garlic, diallyl trisulfide (DATS) displays strong antioxidant capacity. However, it is unknown whether DATS can protect the neurons of SCII.

MATERIALS AND METHODS

In this study, the descending aorta at the distal end of the left subclavian artery was ligated and perfused again after 14 min. Samples including blood and spinal cord (L2-L5) were taken 24 h later for morphological and biochemical examination.

RESULTS

After SCII, the rats showed motor dysfunction, increase apoptosis, malondialdehyde content, mitochondrial biogenesis and dynamic balance disorder. After the application of DATS, the adenosine monophosphate activated protein kinase (AMPK) was activated, the mitochondrial damage was improved, the oxidative stress was weakened, and the neuronal damage was recovered to some extent. However, the addition of compound C significantly weakened the protective effect of DATS.

CONCLUSION

Oxidative stress caused by mitochondrial damage was one of the important mechanisms of neuronal damage in SCII. DATS could activate AMPK, stabilize mitochondrial biogenesis and dynamic balance, and reduce neuronal damage caused by oxidative stress.

Thermosensitive hydrogel-based GPR124 delivery strategy for rebuilding blood-spinal cord barrier

Spinal cord injury (SCI) causes blood-spinal cord barrier (BSCB) disruption, leading to secondary damage, such as hemorrhagic infiltration, inflammatory response, and neuronal cell death. It is of great significance to rebuild the BSCB at the early stage of SCI to alleviate the secondary injury for better prognosis. Yet, current research involved in the reconstruction of BSCB is insufficient. Accordingly, we provide a thermosensitive hydrogel-based G protein-coupled receptor 124 (GPR124) delivery strategy for rebuilding BSCB. Herein, we firstly found that the expression of GPR124 decreased post-SCI and demonstrated that treatment with recombinant GPR124 could partially alleviate the disruption of BSCB post-SCI by restoring tight junctions (TJs) and promoting migration and tube formation of endothelial cells. Interestingly, GPR124 could also boost the energy metabolism of endothelial cells. However, the absence of physicochemical stability restricted the wide usage of GPR124. Hence, we fabricated a thermosensitive heparin-poloxamer (HP) hydrogel that demonstrated sustained GPR124 production and maintained the bioactivity of GPR124 (HP@124) for rebuilding the BSCB and eventually enhancing functional motor recovery post-SCI. HP@124 hydrogel can encapsulate GPR124 at the lesion site by injection, providing prolonged release, preserving wounded tissues, and filling injured tissue cavities. Consequently, it induces synergistically efficient integrated regulation by blocking BSCB rupture, decreasing fibrotic scar formation, minimizing inflammatory response, boosting remyelination, and regenerating axons. Mechanistically, giving GPR124 activates energy metabolism via elevating the expression of phosphoenolpyruvate carboxykinase 2 (PCK2), and eventually restores the poor state of endothelial cells. This research demonstrated that early intervention by combining GPR124 with bioactive multifunctional hydrogel may have tremendous promise for restoring locomotor recovery in patients with central nervous system disorders, in addition to a translational approach for the medical therapy of SCI.

USP18 overexpression protects against spinal cord ischemia/reperfusion injury via regulating autophagy

BACKGROUND

Spinal cord ischemia-reperfusion injury (SCII) is usually caused by spinal surgery, often leading to severe neurological deficits. The ubiquitin-specific protease 18 (USP18) plays a significant role in neurological diseases.

OBJECTIVE

The present study was designed to assess the effects and mechanisms of USP18 on SCII.

METHODS

By inducing transient aortic occlusion and subsequent reperfusion, a rat model of SCII was successfully established. The Basso-Beattie-Bresnahan scores, the inclined plane test, and hematoxylin and eosin (HE) were used to measure locomotor activity and histological changes in the injured spinal cords. Moreover, the SCII cell model was established using PC12 cells under oxygen-glucose deprivation and reoxygenation (OGD/R). Proinflammatory factors (TNF-α, IL-6, and INF-α) were examined using an ELISA kit. Cell apoptosis was assessed by Annexin V-FITC/PI double-staining and TUNEL assays. Western blot was used to detect the expression levels of proteins related to apoptosis and autophagy.

RESULTS

USP18 expression was decreasedin vivo and in vitro SCII models. The upregulation of USP18 ameliorated hind limbs' motor function, inhibiting inflammation and apoptosis after SCII in rats. USP18 overexpression in vitro may protect PC12 cells from OGD/R-induced damage by modulating inflammatory responses and apoptosis. Moreover, Overexpression of USP18 enhanced autophagy to inhibit cell apoptosis induced by SCII in vivo and in vitro.

CONCLUSIONS

In summary, USP18 overexpression protects against SCII via regulating autophagy.

Knockdown of ELF4 aggravates renal injury in ischemia/reperfusion mice through promotion of pyroptosis, inflammation, oxidative stress, and endoplasmic reticulum stress

BACKGROUND

Renal ischemia/reperfusion (I/R) injury is a major cause of acute kidney injury (AKI). Dysfunction of E74-like ETS transcription factor 4 (ELF4) leads to inflammation. This research intended to look into the function and mechanisms of ELF4 in I/R and oxygen-glucose deprivation/reperfusion (OGD/R) model.

RESULTS

In I/R and OGD/R model, ELF4 expression was downregulated. ELF4 knockout aggravated I/R-induced kidney injury, oxidative stress (OS), endoplasmic reticulum stress (ERS), apoptosis, inflammation, and pyroptosis in mice. In HK-2 cells treated with OGD/R, suppression of ELF4 expression inhibited cell proliferation and promoted cell apoptosis, OS, ERS, inflammation, and pyroptosis. Moreover, ELF4 overexpression led to the opposite results.

CONCLUSION

ELF4 deficiency aggravated I/R induced AKI, which was involved in apoptosis, OS, ERS, inflammation, and pyroptosis. Targeting ELF4 may be a promising new therapeutic strategy for preventing inflammation after IR-AKI.

Suppression of neuronal apoptosis and glial activation with modulation of Nrf2/HO-1 and NF-kB signaling by curcumin in streptozotocin-induced diabetic spinal cord central neuropathy

Introduction

Diabetes is a global disease, commonly complicated by neuropathy. The spinal cord reacts to diabetes by neuronal apoptosis, microglial activation, and astrocytosis, with a disturbance in neuronal and glial Nuclear factor erythroid 2-related factor/Heme oxygenase-1 (Nrf2/HO-1) and Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) signaling. Curcumin, a bioactive natural substance, showed neuroprotective role in many diseases. However, its role in the treatment of the diabetic central neuropathy of spinal cord and the underlying mechanisms still need clarification. The present study tried to evaluate the role of curcumin in diabetes-induced central neuropathy of the spinal cord in rats.

Methods

Twenty rats were divided into three groups; group 1: a negative control group; group 2: received streptozotocin (STZ) to induce type I diabetes, and group 3: received STZ + Curcumin (150 mg/kg/day) for eight weeks. The spinal cords were examined for histopathological changes, and immunohistochemical staining for Glia fibrillary acidic protein (GFAP); an astrocyte marker, Ionized calcium-binding adaptor molecule 1 (Iba1), a microglial marker, neuronal nuclear protein (NeuN); a neuronal marker, caspase-3; an apoptosis marker, Nrf2/HO-1, NF-kB, and oxidative stress markers were assessed.

Results

Curcumin could improve spinal cord changes, suppress the expression of Iba1, GFAP, caspase-3, and NF-kB, and could increase the expression of NeuN and restore the Nrf2/HO-1 signaling.

Discussion

Curcumin could suppress diabetic spinal cord central neuropathy, glial activation, and neuronal apoptosis with the regulation of Nrf2/HO-1 and NF-kB signaling.

H2S-mediated inhibition of RhoA/ROCK pathway and noncoding RNAs in ischemic stroke

Ischemic stroke is one of major causes of disability. In the pathological process of ischemic stroke, the up-regulation of Ras homolog gene family, member A (RhoA) and its downstream effector, Ras homolog gene family (Rho)-associated coiled coil-containing kinase (ROCK), contribute to the neuroinflammation, blood-brain barrier (BBB) dysfunction, neuronal apoptosis, axon growth inhibition and astrogliosis. Accumulating evidences have revealed that hydrogen sulphide (H₂S) could reduce brain injury in animal model of ischemic stroke via inhibiting the RhoA/ROCK pathway. Recently, noncoding RNAs (ncRNAs) such as circular RNAs (circRNAs), long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) have attracted much attention because of their essential role in adjusting gene expression both in physiological and pathological conditions. Numerous studies have uncovered the role of RhoA/ROCK pathway and ncRNAs in ischemic stroke. In this review, we focused on the role of H₂S, RhoA/ROCK pathway and ncRNAs in ischemic stroke and aimed to reveal new strategies for preventing and treating this devastating disease.

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.

Acacetin alleviates neuroinflammation and oxidative stress injury via the Nrf2/HO-1 pathway in a mouse model of spinal cord injury

Spinal cord injury (SCI) is a severe central nervous system disease, which may cause serious locomotor deficit. Acacetin is a flavone that possesses antioxidant and anti-inflammatory effects in different human diseases. The main purpose of this study was to explore whether acacetin ameliorates SCI in mice. A model of SCI was established in C57BL/6 mice. The Basso Mouse Scale (BMS) score, BMS subscore, mechanical hypersensitivity, and thermal hypersensitivity of mice were tested for determining the motor function. Immunofluorescence staining was utilized to detect NeuN, GFAP, and Iba-1 levels in spinal cord tissues. ELISA was utilized to assess the contents of proinflammatory factors such as interleukin (IL)-1β, IL-18, and tumor necrosis factor-alpha (TNF-α) in spinal cord tissues. The levels of oxidative stress markers, reactive oxygen species, thiobarbituric acid-reactive substances, superoxide dismutase, catalase, glutathione peroxidase, and glutathione were detected using their corresponding kits. Western blot was employed for estimating the levels of heme oxygenase 1 (HO-1), nuclear factor E2-related factor 2 (Nrf2), and Kelch-like ECH-associated protein 1 (Keap-1). In this study, acacetin treatment recovered the motor function in SCI mice. Acacetin improved neuron integrity and repressed glial cell activation in the spinal cord tissues of SCI mice. Furthermore, acacetin administration reduced the SCI-induced high concentrations of IL-1β, IL-18, and TNF-α, as well as inhibited oxidative stress in SCI mice. Moreover, acacetin activated HO-1/Nrf2 pathway in SCI mice. The neuroprotective effects of acacetin against SCI were reversed by Nrf2 inhibitor. Overall, acacetin alleviated neuroinflammation and oxidative stress injury by activating the Nrf2/HO-1 signaling pathway in the mouse models of SCI.

Targeting neuroinflammation as a preventive and therapeutic approach for perioperative neurocognitive disorders

Perioperative neurocognitive disorders (PND) is a common postoperative complication associated with regional or general anesthesia and surgery. Growing evidence in both patient and animal models of PND suggested that neuroinflammation plays a critical role in the development and progression of this problem, therefore, mounting efforts have been made to develop novel therapeutic approaches for PND by targeting specific factors or steps alongside the neuroinflammation. Multiple studies have shown that perioperative anti-neuroinflammatory strategies via administering pharmacologic agents or performing nonpharmacologic approaches exert benefits in the prevention and management of PND, although more clinical evidence is urgently needed to testify or confirm these results. Furthermore, long-term effects and outcomes with respect to cognitive functions and side effects are needed to be observed. In this review, we discuss recent preclinical and clinical studies published within a decade as potential preventive and therapeutic approaches targeting neuroinflammation for PND.

Naringenin Alleviates Renal Ischemia Reperfusion Injury by Suppressing ER Stress-Induced Pyroptosis and Apoptosis through Activating Nrf2/HO-1 Signaling Pathway

Endoplasmic reticulum (ER) stress, pyroptosis, and apoptosis are critical molecular events in the occurrence and progress of renal ischemia reperfusion (I/R) injury. Naringenin (4′,5,7-trihydroxyflavanone) is one of the most widely consumed flavonoids with powerful antioxidant and anti-inflammatory activities. However, whether naringenin is able to relieve renal I/R injury and corresponding mechanisms have not been fully clarified. This study was aimed at exploring its role and relevant mechanisms in renal I/R injury. The C57Bl/6 mice were randomly assigned to receive administration with naringenin (50 mg/kg/d) or sterile saline (1.0 mL/d) for 3 d by gavage and suffered from renal I/R surgery. One specific ER stress inhibitor, 4-phenylbutyric acid (4-PBA, 100 mg/kg/d), was intraperitoneally administered to validate the regulation of ER stress on pyroptosis and apoptosis. Cultured HK-2 cells went through the process of hypoxia/reoxygenation (H/R) to perform cellular experiments with the incubation of naringenin (200 μM), 4-PBA (5 mM), or brusatol (400 nM). The animal results verified that naringenin obviously relieved renal I/R injury, while it refined renal function and attenuated tissue structural damage. Furthermore, naringenin treatment inhibited I/R-induced ER stress as well as pyroptosis and apoptosis as indicated by decreased levels of specific biomarkers such as GRP78, CHOP, caspase-12, NLRP3, ASC, caspase-11, caspase-4, caspase-1, IL-1β, GSDMD-N, BAX, and cleaved caspase-3 in animals and HK-2 cells. Besides, the upregulated expression of Nrf2 and HO-1 proteins after naringenin treatment suggested that naringenin activated the Nrf2/HO-1 signaling pathway, which was again authenticated by the usage of brusatol (Bru), one unique inhibitor of the Nrf2 pathway. Importantly, the application of 4-PBA showed that renal I/R-generated pyroptosis and apoptosis were able to be regulated by ER stress in vivo and in vitro. In conclusion, naringenin suppressed ER stress by activating Nrf2/HO-1 signaling pathway and further alleviated pyroptosis and apoptosis to protect renal against I/R injury.

Archaea from the gut microbiota of humans: Could be linked to chronic diseases?

Archaea comprise a unique domain of organisms with distinct biochemical and genetic differences from bacteria. Methane-forming archaea, methanogens, constitute the predominant group of archaea in the human gut microbiota, with Methanobrevibacter smithii being the most prevalent. However, the effect of methanogenic archaea and their methane production on chronic disease remains controversial. As perturbation of the microbiota is a feature of chronic conditions, such as cardiovascular disease, neurodegenerative diseases and chronic kidney disease, assessing the influence of archaea could provide a new clue to mitigating adverse effects associated with dysbiosis. In this review, we will discuss the putative role of archaea in the gut microbiota in humans and the possible link to chronic diseases.

Methane Alleviates Lung Injury through the IL-10 Pathway by Increasing T Regulatory Cells in a Mouse Asthma Model

Allergic asthma is associated with allergen-induced airway hyperresponsiveness and inflammatory cell infiltration. While moderate-to-severe asthma with refractory symptoms is difficult to treat, methane is protective against organ damage. In this study, an asthmatic mouse model was established. Airway resistance under acetylcholine stimulation in asthmatic mice and histology of lung tissue injury were determined. EOS infiltration was determined by flow cytometry. Enzyme-linked immunosorbent assays (ELISAs) were performed for the determination of relevant cytokine levels in asthmatic mice with or without methane treatment. The potential mechanisms of methane under anti-IL-10 antibody intraperitoneal intervention were assessed by ELISA and flow cytometry. Pulmonary T regulatory cells (Tregs) were analyzed by flow cytometry, and anti-CD25 antibody was used to block them. Immunoblot analysis was performed to evaluate if methane played a role in the asthmatic lungs via the NF-κB and MAPKs pathways. The results showed that methane significantly improved airway compliance, relieved asthma-induced lung injury, and reduced EOS accumulation and inflammatory mediators in the lungs of ovalbumin-treated asthmatic mice. Anti-IL-10 treatment diminished the ameliorating effect of methane on asthma. In addition, methane enhanced pulmonary Tregs in asthma, which could be blocked by the anti-CD25 antibody. Further analysis revealed that methane decreased p-p65/p65 and p-p38/p38 expression. In conclusion, methane is a readily available and inexpensive molecule potentially suitable for human use, which can alleviate asthma-induced lung injury and EOS infiltration through the IL-10 pathway by increasing Tregs and decreasing NF-κB and p38 MAPK in a mouse model.

Recent Advances in the Role of Nuclear Factor Erythroid-2-Related Factor 2 in Spinal Cord Injury: Regulatory Mechanisms and Therapeutic Options

Nuclear factor erythroid-2-related factor 2 (Nrf2) is a pleiotropic transcription factor, and it has been documented that it can induce defense mechanisms both oxidative stress and inflammatory injury. At present, more and more evidences show that the Nrf2 signaling pathway is a key pharmacological target for the treatment of spinal cord injury (SCI), and activating the Nrf2 signaling pathway can effectively treat the inflammatory injury and oxidative stress after SCI. This article firstly introduces the biological studies of the Nrf2 pathway. Meanwhile, it is more powerful to explain that activating the Nrf2 signaling pathway can effectively treat SCI by deeply exploring the relationship between Nrf2 and oxidative stress, inflammatory injury, and SCI. In addition, several potential drugs for the treatment of SCI by promoting Nrf2 activation and Nrf2-dependent gene expression are reviewed. And some other treatment strategies of SCI by modulating the Nrf2 pathway are also summarized. It will provide new ideas and directions for the treatment of SCI.

Water Treadmill Training Ameliorates Neurite Outgrowth Inhibition Associated with NGR/RhoA/ROCK by Inhibiting Astrocyte Activation following Spinal Cord Injury

Spinal cord injury (SCI) often results in damage to or degeneration of axons. Crosstalk between astrocytes and neurons plays a pivotal role in neurite outgrowth following SCI. Rehabilitative training is a recognized method for the treatment of SCI, but the specific mechanism underlying its effect on axonal outgrowth in the central nervous system (CNS) has not yet been determined. A total of 190 adult male SD rats weighing 200-250 g were randomly divided into eight groups for use as animal models of SCI. Rats were subjected to water treadmill training (TT) for 7 or 14 d. The Basso-Beattie-Bresnahan (BBB) motor function scale, hematoxylin-eosin (HE) staining, Nissl staining, Western blotting, and immunofluorescence were used to measure tissue morphology and the degree of neurological deficit and to determine quantitative expression and accurate localization of the corresponding proteins. We found that TT decreased tissue structure damage and improved functional recovery. TT also promoted the regeneration of neurons and reduced SCI-induced apoptosis SCI around the lesion, as well as significantly increasing the expression of GAP43 and NF200 after SCI. In addition, TT significantly inhibited the injury-induced increase in the expression of proinflammatory factors. Moreover, TT reduced the activation of astrocytes and microglia, accompanied by the reduced expression of C3d and increased expression of S100A10. Finally, TT effectively reduced the level of chondroitin sulfate proteoglycan (CSPG) surrounding the lesion and inhibited the NGR/RhoA/ROCK signaling pathway in neurons after SCI. Overall, we found that TT played a novel role in recovery from SCI by promoting axonal outgrowth associated with NGR/RhoA/ROCK signaling by inhibiting astrocyte activation after SCI.

Maintaining homeostasis of mitochondria and endoplasmic reticulum with NSC228155 alleviates cisplatin-induced acute kidney injury

Acute kidney injury (AKI) is a common complication of hospitalization with high mortality. Approximately 30% of patients receiving cisplatin, the first-line chemotherapy treatment, develop AKI. NSC228155 is a novel compound with potential anti-cancer and anti-bacterial effects. Its therapeutic efficacy in other diseases is unclear. In the present study, we investigated the effect of NSC228155 on cisplatin-induced AKI. The mice were consecutively treated with 2.5 mg/kg of NSC228155 for five days and injected with cisplatin (22 mg/kg) via intraperitoneal injection on day three. NSC228155 strikingly improved the renal function by decreasing the serum creatinine by 52.6% in the cisplatin-induced AKI mice model. Pathologically, NSC228155 profoundly alleviated the tubular damage in Periodic Acid-Schiff staining, and significantly reduced the expression of tubular injury markers and apoptosis in the cisplatin-injured mice kidneys. NSC228155 effectively restored the mitochondrial homeostasis by decreasing damaged mitochondria, activating signals for mitochondrial dynamics and recycling, and corrected mitochondrial dysfunction in ATP production and oxidative stress in the cisplatin model. Transcriptomics and metabolomics analysis on the mice renal cortex suggested that NSC228155 profoundly corrected energy metabolism, especially citrate cycle-related pathways, oxidative stress, and endoplasmic reticulum (ER) stress in the cisplatin-induced AKI kidneys. NSC228155 effectively inhibited ER stress induced by cisplatin or tunicamycin in mice kidneys and HK-2 cells. Co-treatment of NSC228155 with 4-phenylbutyrate or MnTBAP showed a similar therapeutic effect in AKI as the inhibitors or NSC228155 alone did, and corrected the mitochondrial dysfunction and ER stress, respectively, indicating the crosstalk between ER and mitochondria played essential roles in the therapeutic effect of NSC228155 in AKI. Together, these results consistently demonstrated that NSC228155 alleviated cisplatin-induced AKI by restoring the homeostasis in mitochondria and ER, suggesting a therapeutic potential and perhaps a novel strategy for drug discovery.

Electroacupuncture ameliorates neuroinflammation in animal models

Background:

Neuroinflammation refers to a wide range of immune responses occurring in the brain or spinal cord. It is closely related to a variety of neurodegenerative diseases, for which it potentially represents a new direction for treatment. Electroacupuncture (EA) is one method of acupuncture treatment, which can be used as an adjuvant therapy for many diseases. This review focuses on molecular mechanisms of EA in the reduction of neuroinflammation, summarizes relevant basic research and outlines future directions for investigation.

Findings:

A growing body of basic research has shown that EA can ameliorate neuroinflammation centrally (in animal models of ischemic stroke, Alzheimer’s disease, traumatic brain injury, spinal cord injury, Parkinson’s disease and vascular dementia) and peripherally (e.g. after a surgical insult or injection of lipopolysaccharide) and that its effects involve different molecular mechanisms, including activation of the α7 nicotinic acetylcholine receptor signaling pathway and P2 type purinergic receptors, inhibition of nuclear factor κB, and mitigation of damage secondary to oxidative stress and NOD-like receptor protein 3 inflammasome activation.

Conclusions:

EA is capable of regulating multiple cell signal transduction pathways to alleviate neuroinflammation in animal models. Although the findings of animal studies are encouraging, further prospective clinical trials are needed to verify the efficacy of EA for the treatment of neuroinflammation.

MicroRNA-101a-3p mimic ameliorates spinal cord ischemia/reperfusion injury

miR-101a-3p is expressed in a variety of organs and tissues and plays a regulatory role in many diseases, but its role in spinal cord ischemia/reperfusion injury remains unclear. In this study, we established a rat model of spinal cord ischemia/reperfusion injury by clamping the aortic arch for 14 minutes followed by reperfusion for 24 hours. Results showed that miR-101a-3p expression in L4–L6 spinal cord was greatly decreased, whereas MYCN expression was greatly increased. Dual-luciferase reporter assay results showed that miR-101a-3p targeted MYCN. MYCN immunoreactivity, which was primarily colocalized with neurons in L4–L6 spinal tissue, greatly increased after spinal cord ischemia/reperfusion injury. However, intrathecal injection of an miR-101a-3p mimic within 24 hours before injury decreased MYCN, p53, caspase-9 and interleukin-1β expression, reduced p53 immunoreactivity, reduced the number of MYCN/NeuN-positive cells and the number of necrotic cells in L4–L6 spinal tissue, and increased Tarlov scores. These findings suggest that the miR-101a-3p mimic improved spinal ischemia/reperfusion injury-induced nerve cell apoptosis and inflammation by inhibiting MYCN and the p53 signaling pathway. Therefore, miR-101a-3p mimic therapy may be a potential treatment option for spinal ischemia/reperfusion injury.

Immune-responsive gene 1/itaconate activates nuclear factor erythroid 2-related factor 2 in microglia to protect against spinal cord injury in mice

The pathophysiology of spinal cord injury (SCI) involves primary injury and secondary injury. Secondary injury is a major target for SCI therapy, whereas microglia play an important role in secondary injury. The immunoresponsive gene 1 (Irg-1) has been recorded as one of the most significantly upregulated genes in SCI tissues in gene chip data; however, its role in SCI remains unclear. This study aims to illustrate the role of Irg-1 as well as its regulated metabolite itaconate in SCI. It was demonstrated that the expression of Irg-1 was increased in spinal cord tissues in mice as well as in microglia stimulated by lipopolysaccharides (LPS). It was also shown that overexpression of Irg-1 may suppress LPS-induced inflammation in microglia, while these protective effects were attenuated by Nrf2 silencing. In vivo, overexpression of Irg-1 was shown to suppress neuroinflammation and improve motor function recovery. Furthermore, treatment of microglia with itaconate demonstrated similar inflammation suppressive effects as Irg-1 overexpression in vitro and improved motor function recovery in vivo. In conclusion, the current study shows that Irg-1 and itaconate are involved in the recovery process of SCI, either Irg-1 overexpression or itaconate treatment may provide a promising strategy for the treatment of SCI.

Bioactivity of Inhaled Methane and Interactions With Other Biological Gases

A number of studies have demonstrated explicit bioactivity for exogenous methane (CH₄), even though it is conventionally considered as physiologically inert. Other reports cited in this review have demonstrated that inhaled, normoxic air-CH₄ mixtures can modulate the in vivo pathways involved in oxidative and nitrosative stress responses and key events of mitochondrial respiration and apoptosis. The overview is divided into two parts, the first being devoted to a brief review of the effects of biologically important gases in the context of hypoxia, while the second part deals with CH₄ bioactivity. Finally, the consequence of exogenous, normoxic CH₄ administration is discussed under experimental hypoxia- or ischaemia-linked conditions and in interactions between CH₄ and other biological gases, with a special emphasis on its versatile effects demonstrated in pulmonary pathologies.

Lidocaine relieves spinal cord ischemia-reperfusion injury via long non-coding RNA MIAT-mediated Notch1 downregulation

Microglial activation and inflammatory response play a critical role in spinal cord ischemia-reperfusion injury (SCIRI). This study aimed to investigate whether lidocaine relieves SCIRI via modulating MIAT-mediated Notch1 downregulation. Mouse SCIRI was induced by the obstruction of the aortic arch. Lidocaine was injected after reperfusion. Microglial activation and inflammatory response were assessed by Iba1, interleukin 1 beta (IL-1β), and tumor necrosis factor alpha (TNF-α) levels. The interaction between MIAT and Notch1 was assessed by RNA pull-down and RNA immunoprecipitation assays. Lidocaine treatment relieved SCIRI by reducing Iba1 and serum TNF-α and IL-1β levels. After lidocaine treatment, MIAT expression was elevated in lipopolysaccharide- (LPS-) induced BV2 cells. The interference of MIAT and the overexpression of MIAT and Notch1 restored TNF-α and IL-1β levels in supernatants. Notch1 protein was existent in MIAT-pull-down compounds, and the expression of MIAT was markedly elevated in Notch1-immunoprecipitants. The overexpression of MIAT markedly promoted the degradation of Notch1 and increased the level of ubiquitin-bound Notch1 complex. The therapeutic effect of lidocaine on SCIRI mice could be reversed by adeno-associated virus-mediated MIAT knockdown. In conclusion, lidocaine treatment relieved SCIRI via inhibiting microglial activation and reducing the inflammatory response. The molecular mechanism was partly through MIAT-mediated Notch1 downregulation.

Anti-inflammatory and antioxidant effects of astaxanthin following spinal cord injury in a rat animal model

Spinal cord injury (SCI) is a severely debilitating problem leading to substantial decrease in the quality of life. After spinal cord injury, inflammation and oxidative stress plays a key role in initiating the secondary injury cascades leading to progressive tissue degradation and extreme functional deficits. Given that the primary mechanical injuries to spinal cord are rarely repaired, the pharmacological interventions may improve the neurological outcomes caused by secondary injury. Astaxanthin (AST) is considered as a xanthophyll carotenoid with potent antioxidant and anti-inflammatory properties, which has various pharmacological activities. In the present study, we aimed to firstly assess the protective effect of AST, and then to define the AST mechanism of action on a rat model of SCI. Based on the results of von Frey test, AST treatment significantly alleviated the SCI-induced neuropathic pain compared with the control groups (P < 0.05). The expression analysis by western blot shows reduced expression levels of COX-2, TNF-α, IL-1β, and IL-6 following AST treatment (P < 0.05). The activity of antioxidant enzymes was evaluated using ELISA. Therefore, ELISA experiments showed a significant reduction in the level of oxidative stress in SCI rat following AST treatment (P < 0.05). Furthermore, histopathological evaluations revealed that myelinated white matter and motor neuron number were significantly preserved after treatment with AST (P < 0.05). In conclusion, our study shows that AST could improve SCI through anti-inflammatory and antioxidant effects which leads to decreased tissue damage and mechanical pain after SCI.

Imperatorin inhibits mitogen-activated protein kinase and nuclear factor kappa-B signaling pathways and alleviates neuroinflammation in ischemic stroke

AIMS

Microglia-mediated neuroinflammation plays an important role in the pathological process of ischemic stroke, and the effect of imperatorin on post-stroke neuroinflammation is not fully understood.

METHODS

Primary microglia were treated with imperatorin for 2 h followed by LPS (100 ng/ml) for 24 h. The expression of inflammatory cytokines was detected by RT-PCR, ELISA, and Western blot. The activation of MAPK and NF-κB signaling pathways were analyzed by Western blot. The ischemic insult was determined using a transient middle cerebral artery occlusion (tMCAO) model in C57BL/6J mice. Behavior tests were used to assess the neurological deficits of MCAO mice. TTC staining was applied to measure infract volume.

RESULTS

Imperatorin suppressed LPS-induced activation of microglia and pro-inflammatory cytokines release and attenuated ischemic injury in MCAO mice. The results of transcriptome sequencing and Western blot revealed that downregulation of MAPK and NF-κB pathways might contribute to the protective effects of imperatorin.

CONCLUSIONS

Imperatorin downregulated MAPK and NF-κB signaling pathways and exerted anti-inflammatory effects in ischemic stroke, which indicated that imperatorin might be a potential compound for the treatment of stroke.

Inhibition of MALT1 Alleviates Spinal Ischemia/Reperfusion Injury-Induced Neuroinflammation by Modulating Glial Endoplasmic Reticulum Stress in Rats

PURPOSE

Glial activation and the disorders of cytokine secretion induced by endoplasmic reticulum stress (ERS) are crucial pathogenic processes in establishing ischemia/reperfusion (I/R) injury of the brain and spinal cord. This present study aimed to investigate the effects of mucous-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) on spinal cord ischemia/reperfusion (SCI/R) injury via regulating glial ERS.

METHODS

SCI/R was induced by thoracic aorta occlusion-reperfusion in rats. The MALT1-specific inhibitor MI-2 or human recombinant MALT1 protein (hrMALT1) was administrated for three consecutive days after the surgery. Immunofluorescent staining was used to detect the localization of MALT1 and ERS profiles in activated astrocyte and microglia of spinal cord. The ultrastructure of endoplasmic reticulum (ER) was examined by transmission electron microscopy. Blood-spinal cord barrier (BSCB) disruption and noninflammatory status were assessed. The neuron loss and demyelination in the spinal cord were monitored, and the hindlimb motor function was evaluated in SCI/R rats.

RESULTS

Intraperitoneally postoperative MI-2 treatment down-regulated phos-NF-κB (p65) and Bip (ERS marker protein) expression in the spinal cord after SCI/R in rats. Intraperitoneal injection MI-2 attenuated the swelling/dilation of ER of the glia in SCI/R rats. Furthermore, MI-2 attenuated I/R-induced Evans blue (EB) leakage and microglia M1 polarization in spinal cord, implying a role for MALT1 in the BSCB destruction and neuroinflammation after SCI/R in rats. Furthermore, intrathecal injection of hrMALT1 aggravated the fragmentation of neuron, loss of neurofibrils and demyelination caused by I/R, while 4-PBA, an ERS inhibitor, co-treatment with hrMALT1 reversed these effects in SCI/R rats. hrMALT1 administration aggravated the motor deficit index (MDI) scoring, while 4-PBA co-treatment improved SCI/R-induced motor deficits in rats.

CONCLUSION

Inhibition of MALT1 alleviates SCI/R injury-induced neuroinflammation by modulating glial endoplasmic reticulum stress in rats.

Therapeutic effect of methane and its mechanism in disease treatment

Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. It is abundant in marsh gas, livestock rumination, and combustible ice. Little is known about the use of methane in human disease treatment. Current research indicates that methane is useful for treating several diseases including ischemia and reperfusion injury, and inflammatory diseases. The mechanisms underlying the protective effects of methane appear primarily to involve anti-oxidation, anti-inflammation, and anti-apoptosis. In this review, we describe the beneficial effects of methane on different diseases, summarize possible mechanisms by which methane may act in these conditions, and discuss the purpose of methane production in hypoxic conditions. Then we propose several promising directions for the future research.

Luteolin Modulates the NF-E2-Related Factor 2/Glutamate-Cysteine Ligase Pathway in Rats with Spinal Cord Injury

Spinal cord ischemia-reperfusion injury (SCII) easily causes unalterable neurological deficits. We previously demonstrated that the flavonoid luteolin (LU) has strong antioxidant, anti-inflammatory, and other neuroprotective efficacies against SCII. In our current study, we examined the contributions of the NF-E2-related factor 2 (Nrf2)/glutamate-cysteine ligase (GCL) pathway to LU-mediated neuroprotection in the transient abdominal aorta occlusion rat model of SCII. Rats were divided into four groups: Sham surgery, SCII alone, SCII plus LU pretreatment (SCII + LU), and SCII plus cotreatment with LU and the Nrf2 inhibitor ML385 (SCII + LU + ML385). The Basso-Beattie-Bresnahan (BBB) scale was used to assess neurological function, hematoxylin and eosin staining to evaluate pathological change to the spinal cord, and enzyme-linked immunosorbent assay to measure tissue markers of oxidative stress and inflammation induced by SCII. Mitochondrial injury and apoptosis were examined by flow cytometry and expression levels of Nrf2, GCL catalytic subunit (GCLc), and GCL modifier subunit (GCLm) by real-time quantitative polymerase chain reaction. LU pretreatment significantly enhanced recovery of motor function as evidenced by the BBB score and attenuated the pathological damage. Furthermore, LU effectively enhanced the antioxidative activity, alleviated mitochondrial swelling, decreased the expression levels of several proinflammatory cytokines after SCII, and significantly upregulated Nrf2, GCLc, and GCLm expression levels. Cotreatment with ML385 reversed all these protective effects of LU except the anti-inflammatory response. Collectively, these findings indicate that the neuroprotective efficacy of LU depends on suppression of oxidative stress and preservation of mitochondrial function through signaling pathways involving Nrf2 activation and downstream gene expression.

Methane Inhalation Protects Against Lung Ischemia-Reperfusion Injury in Rats by Regulating Pulmonary Surfactant via the Nrf2 Pathway

Methane (CH₄) exerted protective effects against lung ischemia-reperfusion (I/R) injury, but the mechanism remains unclear, especially the role of pulmonary surfactant. Therefore, this study aimed to explore the effects of CH₄ inhalation on pulmonary surfactant in rat lung I/R injury and to elucidate the mechanism. Rats were randomly divided into three groups (n = 6): the sham, I/R control, and I/R CH₄ groups. In the sham group, only thoracotomy was performed on the rats. In the I/R control and I/R CH₄ groups, the rats underwent left hilum occlusion for 90 min, followed by reperfusion for 180 min and ventilation with O₂ or 2.5% CH₄, respectively. Compared with those of the sham group, the levels of large surfactant aggregates (LAs) in pulmonary surfactant, lung compliance, oxygenation decreased, the small surfactant aggregates (SAs), inflammatory response, oxidative stress injury, and cell apoptosis increased in the control group (P < 0.05). Compared to the control treatment, CH₄ increased LA (0.42 ± 0.06 vs. 0.31 ± 0.09 mg/kg), oxygenation (201 ± 11 vs. 151 ± 14 mmHg), and lung compliance (16.8 ± 1.0 vs. 11.5 ± 1.3 ml/kg), as well as total antioxidant capacity and Nrf2 protein expression and decreased the inflammatory response and number of apoptotic cells (P < 0.05). In conclusion, CH₄ inhalation decreased oxidative stress injury, inflammatory response, and cell apoptosis, and improved lung function through Nrf2-mediated pulmonary surfactant regulation in rat lung I/R injury.

Ulinastatin Ameliorates IL-1β-Induced Cell Dysfunction in Human Nucleus Pulposus Cells via Nrf2/NF-κB Pathway

Low back pain (LBP) has been a wide public health concern worldwide. Among the pathogenic factors, intervertebral disc degeneration (IDD) has been one of the primary contributors to LBP. IDD correlates closely with inflammatory response and oxidative stress, involving a variety of inflammation-related cytokines, such as interleukin 1 beta (IL-1β), which could result in local inflammatory environment. Ulinastatin (UTI) is a kind of acidic protein extracted from human urine, which inhibits the release of tumor necrosis factor alpha (TNF-α) and other inflammatory factors to protect organs from inflammatory damage. However, whether this protective effect of UTI on human nucleus pulposus (NP) exists, and how UTI affects the biological behaviors of human NP cells during IDD remain elusive. In this current study, we revealed that UTI could improve the viability of NP cells and promote the proliferation of NP cells. Additionally, UTI could protect human NP cells via ameliorating IL-1β-induced apoptosis, inflammatory response, oxidative stress, and extracellular matrix (ECM) degradation. Molecular mechanism analysis suggested that the protective effect from UTI on IL-1β-treated NP cells were through activating nuclear factor- (erythroid-derived 2-) like 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway and the suppression of NF-κB signaling pathway. Therefore, UTI may be a promising therapeutic medicine to ameliorate IDD.

Polydatin Attenuates OGD/R-Induced Neuronal Injury and Spinal Cord Ischemia/Reperfusion Injury by Protecting Mitochondrial Function via Nrf2/ARE Signaling Pathway

Spinal cord ischemia/reperfusion injury (SCII) is a devastating complication of spinal or thoracic surgical procedures and can lead to paraplegia or quadriplegia. Neuronal cell damage involving mitochondrial dysfunction plays an important role in the pathogenesis of SCII. Despite the availability of various treatment options, there are currently no mitochondria-targeting drugs that have proven effective against SCII. Polydatin (PD), a glucoside of resveratrol, is known to preserve mitochondrial function in central nervous system (CNS) diseases. The aim of the present study was to explore the neuro- and mito-protective functions of PD and its underlying mechanisms. An in vitro model of SCII was established by exposing spinal cord motor neurons (SMNs) to oxygen–glucose-deprivation/reperfusion (OGD/R), and the cells were treated with different dosages of PD for varying durations. PD improved neuronal viability and protected against OGD/R-induced apoptosis and mitochondrial injury in a dose-dependent manner. In addition, PD restored the activity of neuronal mitochondria in terms of mitochondrial membrane potential (MMP), intracellular calcium levels, mitochondrial permeability transition pore (mPTP) opening, generation of reactive oxygen species (ROS), and adenosine triphosphate (ATP) levels. Mechanistically, PD downregulated Keap1 and upregulated Nrf2, NQO-1, and HO-1 in the OGD/R-treated SMNs. Likewise, PD treatment also reversed the neuronal and mitochondrial damage induced by SCII in a mouse model. Furthermore, the protective effects of PD were partially blocked by the Nrf2 inhibitor. Taken together, PD relieves mitochondrial dysfunction-induced neuronal cell damage by activating the Nrf2/ARE pathway and is a suitable therapeutic option for SCII.

Carnosic acid protects against ferroptosis in PC12 cells exposed to erastin through activation of Nrf2 pathway

AIMS

Ferroptosis is involved in the pathogenesis of spinal cord injury (SCI). Carnosic acid (CA) is a natural phenolic diterpene, which possesses diversiform activities. However, whether the protective effect of CA on SCI is partly due to inhibition of ferroptosis was seldom investigated. Therefore, the objective of this study aimed to investigate the role of CA on ferroptosis in PC12 cells and the underlying mechanisms.

MAIN METHODS

Cell viability, malondialdehyde (MDA) contents, glutathione (GSH) levels, and iron levels were detected to identify the construction of ferroptosis model in PC12 cell induced by erastin. The safe concentrations of CA on PC12 cells were measured via cell counting kit-8 (CCK-8) assays. Then, cellular MDA contents, GSH levels, iron levels, reactive species (RS) generation, and mitochondrial morphology were tested to determine the influence of CA on ferroptosis in erastin-treated PC12 cells. In addition, Western blot and RT-qPCR were utilized to detecteddetect the ferroptosis-related genes and proteins expression levels.

KEY FINDINGS

Our study indicated that treatment with CA could reversed the increased MDA, iron, and RS levels, as well as the decreased GSH levels in erastin-treated PC12 cells. The protective effect of CA could be blocked by ML385. The inhibitory effect of CA on ferroptosis probably was partially governed by activation of Nrf2 to regulate the GSH synthesis and metabolism and cellular iron homeostasis.

SIGNIFICANCE

CA can inhibit ferroptosis in PC12 cells induced by erastin via activating Nrf2 pathway, indicating that CA could lead to neuroprotective effect by restraining the occurrence of ferroptosis.

Methane supplementation improves graft function in experimental heart transplantation

BACKGROUND

Maintenance of cell viability during cold storage is a key issue in organ transplantation. Methane (CH₄) bioactivity has recently been recognized in ischemia/reperfusion conditions; we therefore hypothesized that cold storage in CH₄-enriched preservation solution can provide an increased defense against organ dysfunction during experimental heart transplantation (HTX).

METHODS

The hearts of donor Lewis rats were stored for 60 minutes in cold histidine-tryptophan-ketoglutarate (Custodiol [CS]) or CH₄-saturated CS solution (CS-CH₄) (n = 12 each). Standard heterotopic HTX was performed, and 60 minutes later, the left ventricular (LV) pressure-volume relationships LV systolic pressure (LVSP), systolic pressure increment (dP/dtmax), diastolic pressure decrement, and coronary blood flow (CBF) were measured. Tissue samples were taken to detect proinflammatory parameters, structural damage (by light microscopy), endoplasmic reticulum (ER) stress, and apoptosis markers (CCAAT/enhancer binding protein [C/EBP] homologous protein, GRP78, glycogen synthase kinase-3β, very low-density lipoprotein receptor, caspase 3 and 9, B-cell lymphoma 2, and bcl-2-like protein 4), whereas mitochondrial functional changes were analyzed by high-resolution respirometry.

RESULTS

LVSP and dP/dtmax increased significantly at the largest pre-load volumes in CS-CH₄ grafts as compared with the CS group (114.5 ± 16.6 mm Hg vs 82.8 ± 4.6 mm Hg and 3,133 ± 430 mm Hg/s vs 1,739 ± 169 mm Hg/s, respectively); the diastolic function and CBF (2.4 ± 0.4 ml/min/g vs 1.3 ± 0.3 ml/min/g) also improved. Mitochondrial oxidative phosphorylation capacity was more preserved (58.5 ± 9.4 pmol/s/ml vs 27.7 ± 6.6 pmol/s/ml), and cytochrome c release was reduced in CS-CH₄ storage. Signs of HTX-caused myocardial damage, level of ER stress, and the transcription of proapoptotic proteins were significantly lower in CS-CH₄ grafts.

CONCLUSION

The addition of CH₄ during 1 hour of cold storage improved early in vitro graft function and reduced mitochondrial dysfunction and activation of inflammation. Evidence shows that CH₄ reduced ER stress-linked proapoptotic signaling.

Methane-Rich Saline Alleviates CA/CPR Brain Injury by Inhibiting Oxidative Stress, Microglial Activation-Induced Inflammatory Responses, and ER Stress-Mediated Apoptosis

Brain injury induced by cardiac arrest/cardiopulmonary resuscitation (CA/CPR) is the leading cause of death among patients who have recovery of spontaneous circulation (ROSC). Inflammatory response, apoptosis, and oxidative stress are proven pathological mechanisms implicated in neuronal damage. Methane-rich saline (MRS) has been proven that exerts a beneficial protectiveness impact in several models of ischemia-reperfusion injury. The goal of this paper is to ascertain the role of MRS in CA/CPR-induced brain injury and its potential mechanisms. The tracheal intubation of Sprague-Dawley (SD) rats was clamped for 6 min to establish an asphyxiating cardiac arrest model. After that, chest compressions were applied; then, MRS or saline was administered immediately post-ROSC, the rats were sacrificed, and brain tissue was collected at the end of 6 hours. We observed that MRS treatment attenuated neuronal damage in the hippocampal CA1 region by inhibiting microglial activation, leading to a decrease in the overexpression of proinflammatory cytokines such as TNF-α, IL-6, and iNOS. The results also illustrated that MRS treatment diminished apoptosis in the hippocampal CA1 region , reduced the expression of apoptosis-associated proteins Bax and cleaved caspase9, and increased Bcl-2 expression, as well as inhibited the expression of endoplasmic reticulum (ER) stress pathway-related proteins GRP78, ATF4, and CHOP. Further findings showed that MRS treatment significantly attenuated hippocampal ROS and MDA levels and increased GSH and SOD antioxidant factor levels, which indicated that MRS treatment could inhibit oxidative stress. Our results suggest that MRS exerts a protective effect against CA/CPR brain injury, by inhibiting oxidative stress, microglial activation-induced inflammatory responses, and ER stress-mediated apoptosis.

Sodium Tanshinone IIA Silate Exerts Microcirculation Protective Effects against Spinal Cord Injury In Vitro and In Vivo

Spinal cord microcirculation involves functioning endothelial cells at the blood spinal cord barrier (BSCB) and maintains normal functioning of spinal cord neurons, axons, and glial cells. Protection of both the function and integrity of endothelial cells as well as the prevention of BSCB disruption may be a strong strategy for the treatment of spinal cord injury (SCI) cases. Sodium Tanshinone IIA silate (STS) is used for the treatment of coronary heart disease and improves microcirculation. Whether STS exhibits protective effects for SCI microcirculation is not yet clear. The purpose of this study is to investigate the protective effects of STS on oxygen-glucose deprivation- (OGD-) induced injury of spinal cord endothelial cells (SCMECs) in vitro and to explore effects on BSCB and neurovascular protection in vivo. SCMECs were treated with various concentrations of STS (1 μM, 3 μM, and 10 μM) for 24 h with or without OGD-induction. Cell viability, tube formation, migration, and expression of Notch signaling pathway components were evaluated. Histopathological evaluation (H&E), Nissl staining, BSCB permeability, and the expression levels of von Willebrand Factor (vWF), CD31, NeuN, and Notch signaling pathway components were analyzed. STS was found to improve SCMEC functions and reduce inflammatory mediators after OGD. STS also relieved histopathological damage, increased zonula occludens-1 (ZO-1), inhibited BSCB permeability, rescued microvessels, protected motor neuromas, and improved functional recovery in a SCI model. Moreover, we uncovered that the Notch signaling pathway plays an important role during these processes. These results indicated that STS protects microcirculation in SCI, which may be used as a therapeutic strategy for SCI in the future.

Normobaric hyperoxia plays a protective role against renal ischemia-reperfusion injury by activating the Nrf2/HO-1 signaling pathway

Following renal ischemia-reperfusion injury (RIRI), because of the decrease in oxygen supply to the kidney, a large amount of oxygen-free radicals is generated, and in severe cases, tissue cells will undergo apoptosis or even die. Normobaric hyperoxia (NBHO) is a very common clinical adjuvant treatment. It restores the oxygen supply after renal ischemia and combats oxidative stress in tissues, thus playing a protective role. In this study, our aim is to elucidate the protective mechanism of NBHO inhalation in a rat RIRI model. We performed a surgical excision of the left kidney of the rat and established a right kidney solitary kidney model. Later, the right renal pedicle of the rat was clamped using a non-invasive vascular clamp for 45 min. After the vascular clamp was released and reperfused for 24 h, the rat was placed in a closed oxygen chamber. It was subjected to inhalation of high-concentration oxygen (50%-55%), 2 h daily, for 7 days.RIRI induces postoperative weight loss, impaired renal function, increased oxygen free radicals, reduced antioxidant substances, increased histopathological damage, and increased levels of apoptosis. These effects were significantly improved after treatment with NBHO. At the same time, NBHO significantly increased the expression levels of Nrf2 and HO-1 in the tissues after RIRI. To verify whether HO-1 induced by Nrf2 is involved in the resistance to oxidative stress, after the rat RIRI and before inhaling NBHO, we intraperitoneally injected HO-1 specific inhibitor zinc protoporphyrin (ZnPP) (45 μmol/Kg). However, we found that ZnPP reversed the protective effect of NBHO on RIRI in rats. Combining all the results, we have demonstrated the protective effect of NBHO on RIRI, which can be at least partially attributed to the activation of the Nrf2/HO-1 antioxidative stress pathway.

Methane Ameliorates Lipopolysaccharide-Induced Acute Orchitis by Anti-inflammatory, Antioxidative, and Antiapoptotic Effects via Regulation of the PK2/PKR1 Pathway

Objective

The present study is aimed at investigating the anti-inflammatory, antioxidative, and antiapoptotic effects of methane on lipopolysaccharide- (LPS-) induced acute orchitis and its potential mechanisms.

Methods

Adult male rats were intraperitoneally (i.p.) injected with methane-rich saline (MS, 20 mL/kg) following LPS (5 mg/kg, i.p.). The survival rate was assessed every 12 h until 72 h after LPS induction, and surviving rats were sacrificed for further detection. The wet/dry (W/D) ratio was determined, and testicular damage was histologically assessed. Inflammatory cytokines in the testes and serum, including interleukin-1β (IL-1β), IL-6, IL-10, and tumor necrosis factor-α (TNF-α), were measured using ELISA and RT-qPCR. Oxidative stress was evaluated by the level of superoxide dismutase (SOD) and malondialdehyde (MDA). Testicular apoptosis was detected via TUNEL staining. The expression of prokineticin 2 (PK2)/prokineticin receptor 1 (PKR1) was also analyzed using RT-qPCR, western blotting, and immunohistochemistry.

Results

It was found that methane significantly prolonged rat survival, decreased the W/D ratio, alleviated LPS-induced histological changes, and reduced apoptotic cells in the testes. Additionally, methane suppressed and promoted the production of pro- and anti-inflammatory cytokines, respectively. Furthermore, methane significantly increased SOD levels, decreased MDA levels, and decreased testicular expression of PK2 and PKR1. Therefore, methane exerts therapeutic effects on acute orchitis and might be a new and convenient strategy for the treatment of inflammation-related testicular diseases.

Astaxanthin alleviates spinal cord ischemia-reperfusion injury via activation of PI3K/Akt/GSK-3β pathway in rats

BACKGROUND

Ischemia-reperfusion injury of the spinal cord (SCII) often leads to unalterable neurological deficits, which may be associated with apoptosis induced by oxidative stress and inflammation. Astaxanthin (AST) is a strong antioxidant and anti-inflammatory agent with multitarget neuroprotective effects. This study aimed to investigate the potential therapeutic effects of AST for SCII and the molecular mechanism.

METHODS

Rat models of SCII with abdominal aortic occlusion for 40 min were carried out to investigate the effects of AST on the recovery of SCII. Tarlov's scores were used to assess the neuronal function; HE and TUNEL staining were used to observe the pathological morphology of lesions. Neuron oxidative stress and inflammation were measured using commercial detection kits. Flow cytometry was conducted to assess the mitochondrial swelling degree. Besides, Western blot assay was used to detect the expression of PI3K/Akt/GSK-3β pathway-related proteins, as well as NOX2 and NLRP3 proteins.

RESULTS

The results demonstrated that AST pretreatment promoted the hind limb motor function recovery and alleviated the pathological damage induced by SCII. Moreover, AST significantly enhanced the antioxidative stress response and attenuated mitochondrial swelling. However, AST pretreatment hardly inhibited the levels of proinflammatory cytokines after SCII. Most importantly, AST activated p-Akt and p-GSK-3β expression levels. Meanwhile, cotreatment with LY294002 (a PI3K inhibitor) was found to abolish the above protective effects observed with the AST pretreatment.

CONCLUSION

Overall, these results suggest that AST pretreatment not only mitigates pathological tissue damage but also effectively improves neural functional recovery following SCII, primarily by alleviating oxidative stress but not inhibiting inflammation. A possible underlying molecular mechanism of AST may be mainly attributed to the activation of PI3K/Akt/GSK-3β pathway.

Salidroside Ameliorates Mitochondria-Dependent Neuronal Apoptosis after Spinal Cord Ischemia-Reperfusion Injury Partially through Inhibiting Oxidative Stress and Promoting Mitophagy

Ischemia-reperfusion injury is the second most common injury of the spinal cord and has the risk of neurological dysfunction and paralysis, which can seriously affect patient quality of life. Salidroside (Sal) is an active ingredient extracted from Herba Cistanche with a variety of biological attributes such as antioxidant, antiapoptotic, and neuroprotective activities. Moreover, Sal has shown a protective effect in ischemia-reperfusion injury of the liver, heart, and brain, but its effect in ischemia-reperfusion injury of the spinal cord has not been elucidated. Here, we demonstrated for the first time that Sal pretreatment can significantly improve functional recovery in mice after spinal cord ischemia-reperfusion injury and significantly inhibit the apoptosis of neurons both in vivo and in vitro. Neurons have a high metabolic rate, and consequently, mitochondria, as the main energy-supplying suborganelles, become the main injury site of spinal cord ischemia-reperfusion injury. Mitochondrial pathway-dependent neuronal apoptosis is increasingly confirmed by researchers; therefore, Sal's effect on mitochondria naturally attracted our attention. By means of a range of experiments both in vivo and in vitro, we found that Sal can reduce reactive oxygen species production through antioxidant stress to reduce mitochondrial permeability and mitochondrial damage, and it can also enhance the PINK1-Parkin signaling pathway and promote mitophagy to eliminate damaged mitochondria. In conclusion, our results show that Sal is beneficial to the protection of spinal cord neurons after ischemia-reperfusion injury, mainly by reducing apoptosis associated with the mitochondrial-dependent pathway, among which Sal's antioxidant and autophagy-promoting properties play an important role.

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.

CO-Releasing Molecule (CORM)-3 Ameliorates Spinal Cord-Blood Barrier Disruption Following Injury to the Spinal Cord

Spinal cord injury (SCI) is a clinical tough neurological problem without efficient cure currently. Blood-spinal cord barrier (BSCB) interruption is not only a crucial pathological feature for SCI process but is a possible target for future SCI treatments; however, few treatments have been developed to intervene BSCB. In the present study, we intravenously injected CO-releasing molecule3 (CORM-3), a classical exogenous CO donor, to the rats experiencing SCI and assessed its protection on BSCB integrity in rats. Our results demonstrated that the exogenous increasing of CO by CORM-3 blocked the tight junction (TJ) protein degeneration and neutrophils infiltration, subsequently suppressed the BSCB damage and improved the motor recovery after SCI. And we certified that the CO-induced down-regulation of MMP-9 expression and activity in neutrophil might be associated with the NF-κB signaling. Taken together, our study indicates that CO-releasing molecule (CORM)-3 ameliorates BSCB after spinal cord injury.

Rosmarinic acid exerts a neuroprotective effect on spinal cord injury by suppressing oxidative stress and inflammation via modulating the Nrf2/HO-1 and TLR4/NF-κB pathways

Spinal cord injury (SCI) is a severe central nervous system injury for which few efficacious drugs are available. Rosmarinic acid (RA), a water-soluble polyphenolic phytochemical, has antioxidant, anti-inflammatory, and anti-apoptotic properties. However, the effect of RA on SCI is unclear. We investigated the therapeutic effect and underlying mechanism of RA on SCI. Using a rat model of SCI, we showed that RA improved locomotor recovery after SCI and significantly mitigated neurological deficit, increased neuronal preservation, and reduced apoptosis. Also, RA inhibited activation of microglia and the release of TNF-α, IL-6, and IL-1β and MDA. Moreover, proteomics analyses identified the Nrf2 and NF-κB pathways as targets of RA. Pretreatment with RA increased levels of Nrf2 and HO-1 and reduced those of TLR4 and MyD88 as well as phosphorylation of IκB and subsequent nuclear translocation of NF-κB-p65. Using H2O2- and LPS-induced PC12 cells, we found that RA ameliorated the H2O2-induced decrease in viability and increase in apoptosis and oxidative injury by activating the Nrf2/HO-1 pathway. Also, LPS-induced cytotoxicity and increased apoptosis and inflammatory injury in PC-12 cells were mitigated by RA by inhibiting the TLR4/NF-κB pathway. The Nrf2 inhibitor ML385 weakened the effect of RA on oxidant stress, inflammation and apoptosis in SCI rats, and significantly increased the nuclear translocation of NF-κB. Therefore, the neuroprotective effect on SCI of RA may be due to its antioxidant and anti-inflammatory properties, which are mediated by modulation of the Nrf2/HO-1 and TLR4/NF-κB pathways. Moreover, RA activated Nrf2/HO-1, which amplified its inhibition of the NF-κB pathway.