Potential Contribution of NF-κB in Neuronal Cell Death in the Glutathione Peroxidase-1 Knockout Mouse in Response to Ischemia-Reperfusion Injury

Ameliorative effect of resveratrol on acute ocular hypertension induced retinal injury through the SIRT1/NF-κB pathway

Glaucoma is a kind of neurodegenerative disorder characterized by irreversible loss of retinal ganglion cells (RGCs) and permanent visual impairment. It is reported that resveratrol (RES) is a promising drug for neurodegenerative diseases. However, the detailed molecular mechanisms underlying its protective potential have not yet been fully elucidated. The present study sought to investigate whether resveratrol could protect RGCs and retinal function triggered by acute ocular hypertension injury through the SIRT1/NF-κB pathway. An experimental glaucoma model was generated in C57BL/6J mice. Resveratrol was intraperitoneally injected for 5 days. Sirtinol was injected intravitreally on the day of retinal AOH injury. RGC survival was determined using immunostaining. TUNEL staining was conducted to evaluate retinal cell apoptosis. ERG was used to evaluate visual function. The proteins Brn3a, SIRT1, NF-κB, IL-6, Bax, Bcl2, and Cleaved Caspase3 were determined using western blot. The expression and localisation of SIRT1 and NF-κB in the retina were detected by immunofluorescence. Our data indicated that resveratrol treatment significantly increased Brn3a-labelled RGCs and reduced RGC apoptosis caused by AOH injury. Resveratrol administration also remarkably decreased NF-κB, IL-6, Bax, and Cleaved Caspase3 proteins and increased SIRT1 and Bcl2 proteins. Furthermore, resveratrol treatment obviously inhibited the reduction in ERG caused by AOH injury. Importantly, simultaneous administration of resveratrol and sirtinol abrogated the protective effect of resveratrol, decreased NF-κB protein expression, and increased SIRT1 protein levels. These results suggest that resveratrol administration significantly mitigates retinal AOH-induced RGCs loss and retinal dysfunction, and that this neuroprotective effect is partially regulated through the SIRT1/NF-κB pathway.

Ameliorative effect of Alangium chinense (Lour.) Harms on rheumatoid arthritis by reducing autophagy with targeting regulate JAK3-STAT3 and COX-2 pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Alangium chinense has been used as traditional folk medicine for centuries to treat rheumatoid arthritis (RA) by Guizhou Miao nationality with remarkable clinical effect. But the mechanism of its anti-RA is not fully clarified.

AIM OF THE STUDY

To explore the effect and underlying mechanism of A. chinense against RA.

MATERIAL AND METHODS

RA rats were induced by CII/IFA, and oral administrated with or without ethyl acetate extracts of Alangium chinense (ACEE) and tripterygium glycosides (GTW). Then arthritis scores, inflammatory factors in serum and histological evaluation were evaluated to assess the degree of joints disease. Proteomics were conducted via LC-MS/MS to clarify the mechanism of ACEE preliminarily, and further examined by immunohistochemistry, immunofluorescence, western botting, and molecular docking.

RESULTS

ACEE decreased joints swelling, cell abscission and necrosis of joint tissues arthropathy of RA rats, and attenuated expression of TNF-α, IL-1β, IL-6, PGE2, TGF-β. Meanwhile, differentially expressed proteins in the ACEE treated groups were observed, which were involved in RA, spliceosome, cell adhesion molecules, phagosome and lysosome signaling pathways. Moreover, ACEE significantly ameliorated arthropathy, suppressed JAK-STAT pathway (JAK3, p-JAK3, STAT3, iNOS, RANKL), COX-2 pathway (COX-2, TNF-α, IL-6I, L-1β, 5-LOX), and autophagic signaling pathway (LC3-Ⅰ, LC3-Ⅱ, p62, mTOR). But it showed little effect on the expression of COX-1, JAK1, JAK2, TyK2.

CONCLUSION

It is the first evidence that A. chinense significantly ameliorates RA, and the underlying immune mechanism involves reducing autophagy with targeting regulate JAK3-STAT3 and COX-2 pathways.

Roflumilast attenuates neuroinflammation post retinal ischemia/reperfusion injury by regulating microglia phenotype via the Nrf2/STING/NF-κB pathway

PURPOSE

The abnormal polarisation of microglial cells (MGs) following retinal ischemia/reperfusion (RIR) initiates neuroinflammation and progressive death of retinal ganglion cells (RGCs), causing increasingly severe and irreversible visual dysfunction. Roflumilast (Roflu) is a promising candidate for treating neuroinflammatory diseases. This study aimed to explore whether Roflu displayed a cytoprotective effect against RIR-induced neuroinflammation and to characterise the underlying signalling pathway.

METHODS

The effects and mechanism of Roflu against RIR injury were investigated in C57BL/6J mice and the BV2 cell line. We used quantitative real-time PCR and enzyme-linked immunosorbent assay to examine the levels of inflammatory factors. Furthermore, haematoxylin and eosin and immunofluorescence (IF) stainings were used to assess the morphology of the retina and the states of MGs and RGCs. Reactive oxygen species (ROS) levels were examined using a ROS assay kit, while whole-genome sequencing analysis was conducted to identify altered pathways and molecules. Western blotting and IF staining were used to quantify the proteins associated with the nuclear factor erythroid 2-related factor 2 (Nrf2)/stimulator of interferon gene (STING)/nuclear factor kappa beta (NF-κB) pathway.

RESULTS

MG polarisation includes the pro-inflammatory and neurotoxic M1 phenotype as well as the anti-inflammatory and neuroprotective M2 phenotype. Roflu significantly attenuated MG activation and contributed to a shift in the MG phenotype from M1 to M2. Moreover, Roflu decreased ROS release and increased heme oxygenase 1 and NAD(P)H quinone oxidoreductase 1 expression. In vitro and in vivo experiments validated that Roflu exerted its neuroprotective effects primarily by upregulating the Nrf2/STING/NF-κB pathway. However, these effects were abrogated when the Nrf2 expression was inhibited by pharmacological or genetic manipulation.

CONCLUSIONS

Roflu suppressed RIR-induced neuroinflammation by driving the shift of MG polarisation from M1 to M2 phenotype, which was mediated by the upregulation of the Nrf2/STING/NK-κB pathway.

The Effect of Simvastatin on the Dynamics of NF-κB-Regulated Neurodegenerative and Neuroprotective Processes in the Acute Phase of Ischemic Stroke

Statins are lipid-lowering drugs that act by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A reductase, a rate-limiting enzyme in cholesterol biosynthesis. Animal studies have shown neuroprotective effects of statins in cerebral stroke. However, the underlying mechanisms are not fully understood. The nuclear factor-kappa B (NF-κB) transcription factor is involved in the regulation of apoptosis in stroke. Different dimers of NF-κB regulate the gene expression of proteins involved in both neurodegeneration and neuroprotection. We aimed to determine whether simvastatin improves stroke outcome via inhibition of the RelA/p65-containing subunit and downregulation of stroke-induced pro-apoptotic genes or via activation of NF-κB dimers containing the c-Rel subunit and upregulation of anti-apoptotic genes during the acute stroke phase. Eighteen-month-old Wistar rats, subjected to permanent MCAO or sham surgery, were administered simvastatin (20 mg/kg b.w.) or saline for 5 days before the procedure. Stroke outcome was determined by measuring cerebral infarct and assessing motor functions. The expression of NF-κB subunits in various cell populations was investigated using immunofluorescence/confocal microscopy. RelA and c-Rel were detected by WB. The NF-κB-DNA binding activity was investigated using EMSA, and expression of Noxa, Puma, Bcl-2, and Bcl-x genes was analyzed by qRT-PCR. Results showed a 50% infarct size reduction and significant motor function improvement in the simvastatin-treated animals which correlated with a decrease in RelA and a transient increase in the c-Rel level in the nucleus, normalization of the NF-κB-DNA binding activity, and downregulation of the NF-κB-regulated genes. Our results provide new insights into the statin-mediated neuroprotective action against stroke based on NF-κB pathway inhibition.

Distinct Roles of CK2- and AKT-Mediated NF-κB Phosphorylations in Clasmatodendrosis (Autophagic Astroglial Death) within the Hippocampus of Chronic Epilepsy Rats

The downregulation of glutathione peroxidase-1 (GPx1) plays a role in clasmatodendrosis (an autophagic astroglial death) in the hippocampus of chronic epilepsy rats. Furthermore, N-acetylcysteine (NAC, a GSH precursor) restores GPx1 expression in clasmatodendritic astrocytes and alleviates this autophagic astroglial death, independent of nuclear factor erythroid-2-related factor 2 (Nrf2) activity. However, the regulatory signal pathways of these phenomena have not been fully explored. In the present study, NAC attenuated clasmatodendrosis by alleviating GPx1 downregulation, casein kinase 2 (CK2)-mediated nuclear factor-κB (NF-κB) serine (S) 529 and AKT-mediated NF-κB S536 phosphorylations. 2-[4,5,6,7-Tetrabromo-2-(dimethylamino)-1H-benzo[d]imidazole-1-yl]acetic acid (TMCB; a selective CK2 inhibitor) relieved clasmatodendritic degeneration and GPx1 downregulation concomitant with the decreased NF-κB S529 and AKT S473 phosphorylations. In contrast, AKT inhibition by 3-chloroacetyl-indole (3CAI) ameliorated clasmatodendrosis and NF-κB S536 phosphorylation, while it did not affect GPx1 downregulation and CK2 tyrosine (Y) 255 and NF-κB S529 phosphorylations. Therefore, these findings suggest that seizure-induced oxidative stress may diminish GPx1 expression by increasing CK2-mediated NF-κB S529 phosphorylation, which would subsequently enhance AKT-mediated NF-κB S536 phosphorylation leading to autophagic astroglial degeneration.

EGCG Attenuates CA1 Neuronal Death by Regulating GPx1, NF-κB S536 Phosphorylation and Mitochondrial Dynamics in the Rat Hippocampus following Status Epilepticus

Epigallocatechin-3-gallate (EGCG) is an antioxidant that directly scavenges reactive oxygen species (ROS) and inhibits pro-oxidant enzymes. Although EGCG protects hippocampal neurons from status epilepticus (SE, a prolonged seizure activity), the underlying mechanisms are not fully understood. As the preservation of mitochondrial dynamics is essential for cell viability, it is noteworthy to elucidate the effects of EGCG on impaired mitochondrial dynamics and the related signaling pathways in SE-induced CA1 neuronal degeneration, which are yet unclear. In the present study, we found that EGCG attenuated SE-induced CA1 neuronal death, accompanied by glutathione peroxidase-1 (GPx1) induction. EGCG also abrogated mitochondrial hyperfusion in these neurons by the preservation of extracellular signal-regulated kinase 1/2 (ERK1/2)-dynamin-related protein 1 (DRP1)-mediated mitochondrial fission, independent of c-Jun N-terminal kinase (JNK) activity. Furthermore, EGCG abolished SE-induced nuclear factor-κB (NF-κB) serine (S) 536 phosphorylation in CA1 neurons. ERK1/2 inhibition by U0126 diminished the effect of EGCG on neuroprotection and mitochondrial hyperfusion in response to SE without affecting GPx1 induction and NF-κB S536 phosphorylation, indicating that the restoration of ERK1/2-DRP1-mediated fission may be required for the neuroprotective effects of EGCG against SE. Therefore, our findings suggest that EGCG may protect CA1 neurons from SE insults through GPx1-ERK1/2-DRP1 and GPx1-NF-κB signaling pathways, respectively.

The role of glutathione peroxidase-1 in health and disease

Glutathione peroxidase 1 (GPx1) is an important cellular antioxidant enzyme that is found in the cytoplasm and mitochondria of mammalian cells. Like most selenoenzymes, it has a single redox-sensitive selenocysteine amino acid that is important for the enzymatic reduction of hydrogen peroxide and soluble lipid hydroperoxides. Glutathione provides the source of reducing equivalents for its function. As an antioxidant enzyme, GPx1 modulates the balance between necessary and harmful levels of reactive oxygen species. In this review, we discuss how selenium availability and modifiers of selenocysteine incorporation alter GPx1 expression to promote disease states. We review the role of GPx1 in cardiovascular and metabolic health, provide examples of how GPx1 modulates stroke and provides neuroprotection, and consider how GPx1 may contribute to cancer risk. Overall, GPx1 is protective against the development and progression of many chronic diseases; however, there are some situations in which increased expression of GPx1 may promote cellular dysfunction and disease owing to its removal of essential reactive oxygen species.

Crosstalk Between GABAergic Neurotransmission and Inflammatory Cascades in the Post-ischemic Brain: Relevance for Stroke Recovery

Adaptive plasticity processes are required involving neurons as well as non-neuronal cells to recover lost brain functions after an ischemic stroke. Recent studies show that gamma-Aminobutyric acid (GABA) has profound effects on glial and immune cell functions in addition to its inhibitory actions on neuronal circuits in the post-ischemic brain. Here, we provide an overview of how GABAergic neurotransmission changes during the first weeks after stroke and how GABA affects functions of astroglial and microglial cells as well as peripheral immune cell populations accumulating in the ischemic territory and brain regions remote to the lesion. Moreover, we will summarize recent studies providing data on the immunomodulatory actions of GABA of relevance for stroke recovery. Interestingly, the activation of GABA receptors on immune cells exerts a downregulation of detrimental anti-inflammatory cascades. Conversely, we will discuss studies addressing how specific inflammatory cascades affect GABAergic neurotransmission on the level of GABA receptor composition, GABA synthesis, and release. In particular, the chemokines CXCR4 and CX3CR1 pathways have been demonstrated to modulate receptor composition and synthesis. Together, the actual view on the interactions between GABAergic neurotransmission and inflammatory cascades points towards a specific crosstalk in the post-ischemic brain. Similar to what has been shown in experimental models, specific therapeutic modulation of GABAergic neurotransmission and inflammatory pathways may synergistically promote neuronal plasticity to enhance stroke recovery.

Cognitive enhancement and neuroprotective effects of OABL, a sesquiterpene lactone in 5xFAD Alzheimer's disease mice model

Alzheimer's disease (AD) is a neurodegenerative disease in which oxidative stress and neuroinflammation were demonstrated to be associated with neuronal loss and cognitive deficits. However, there are still no specific treatments that can prevent the progression of AD. In this study, a screening of anti-inflammatory hits from 4207 natural compounds of two different molecular libraries indicated 1,6-O,O-diacetylbritannilactone (OABL), a 1,10-seco-eudesmane sesquiterpene lactone isolated from the herb Inula britannica L., exhibited strong anti-inflammatory activity in vitro as well as favorable BBB penetration property. OABL reduced LPS-induced neuroinflammation in BV-2 microglial cells as assessed by effects on the levels of inflammatory mediators including NO, PGE₂, TNF-α, iNOS, and COX-2, as well as the translocation of NF-κB. Besides, OABL also exhibited pronounced neuroprotective effects against oxytosis and ferroptosis in the rat pheochromocytoma PC12 cell line. For in vivo research, OABL (20 mg/kg B.W., i.p.) for 21 d attenuated the impairments in cognitive function observed in 6-month-old 5xFAD mice, as assessed with the Morris water maze test. OABL restored neuronal damage and postsynaptic density protein 95 (PSD95) expression in the hippocampus. OABL also significantly reduced the accumulation of amyloid plaques, the Aβ expression, the phosphorylation of Tau protein, and the expression of BACE1 in AD mice brain. In addition, OABL attenuated the overactivation of microglia and astrocytes by suppressing the expressions of inflammatory cytokines, and increased glutathione (GSH) and reduced malondialdehyde (MDA) and super oxide dismutase (SOD) levels in the 5xFAD mice brain. In conclusion, these results highlight the beneficial effects of the natural product OABL as a novel treatment with potential application for drug discovery in AD due to its pharmacological profile.

Selenium, a Micronutrient That Modulates Cardiovascular Health via Redox Enzymology

Selenium (Se) is a trace nutrient that promotes human health through its incorporation into selenoproteins in the form of the redox-active amino acid selenocysteine (Sec). There are 25 selenoproteins in humans, and many of them play essential roles in the protection against oxidative stress. Selenoproteins, such as glutathione peroxidase and thioredoxin reductase, play an important role in the reduction of hydrogen and lipid hydroperoxides, and regulate the redox status of Cys in proteins. Emerging evidence suggests a role for endoplasmic reticulum selenoproteins, such as selenoproteins K, S, and T, in mediating redox homeostasis, protein modifications, and endoplasmic reticulum stress. Selenoprotein P, which functions as a carrier of Se to tissues, also participates in regulating cellular reactive oxygen species. Cellular reactive oxygen species are essential for regulating cell growth and proliferation, protein folding, and normal mitochondrial function, but their excess causes cell damage and mitochondrial dysfunction, and promotes inflammatory responses. Experimental evidence indicates a role for individual selenoproteins in cardiovascular diseases, primarily by modulating the damaging effects of reactive oxygen species. This review examines the roles that selenoproteins play in regulating vascular and cardiac function in health and disease, highlighting their antioxidant and redox actions in these processes.

Identification of upregulated NF-κB inhibitor alpha and IRAK3 targeting lncRNA following intracranial aneurysm rupture-induced subarachnoid hemorrhage

Background

This study was performed to identify genes and lncRNAs involved in the pathogenesis of subarachnoid hemorrhage (SAH) from ruptured intracranial aneurysm (RIA).

Methods

Microarray GSE36791 was downloaded from Gene Expression Omnibus (GEO) database followed by the identification of significantly different expressed RNAs (DERs, including lncRNA and mRNA) between patients with SAH and healthy individuals. Then, the functional analyses of DEmRNAs were conducted and weighted gene co-expression network analysis (WGCNA) was also performed to extract the modules associated with SAH. Following, the lncRNA-mRNA co-expression network was constructed and the gene set enrichment analysis (GSEA) was performed to screen key RNA biomarkers involved in the pathogenesis of SAH from RIA. We also verified the results in a bigger dataset GSE7337.

Results

Totally, 561 DERs, including 25 DElncRNAs and 536 DEmRNAs, were identified. Functional analysis revealed that the DEmRNAs were mainly associated with immune response-associated GO-BP terms and KEGG pathways. Moreover, there were 6 modules significantly positive-correlated with SAH. The lncRNA-mRNA co-expression network contained 2 lncRNAs (LINC00265 and LINC00937) and 169 mRNAs. The GSEA analysis showed that these two lncRNAs were associated with three pathways (cytokine-cytokine receptor interaction, neurotrophin signaling pathway, and apoptosis). Additionally, IRAK3 and NFKBIA involved in the neurotrophin signaling pathway and apoptosis while IL1R2, IL18RAP and IL18R1 was associated with cytokine-cytokine receptor interaction pathway. The expression levels of these genes have the same trend in GSE36791 and GSE7337.

Conclusion

LINC00265 and LINC00937 may be implicated with the pathogenesis of SAH from RIA. They were involved in three important regulatory pathways. 5 mRNAs played important roles in the three pathways.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02156-1.

Regulation of Mitochondrial Dynamics in Parkinson's Disease-Is 2-Methoxyestradiol a Missing Piece?

Mitochondria, as "power house of the cell", are crucial players in cell pathophysiology. Beyond adenosine triphosphate (ATP) production, they take part in a generation of reactive oxygen species (ROS), regulation of cell signaling and cell death. Dysregulation of mitochondrial dynamics may lead to cancers and neurodegeneration; however, the fusion/fission cycle allows mitochondria to adapt to metabolic needs of the cell. There are multiple data suggesting that disturbed mitochondrial homeostasis can lead to Parkinson's disease (PD) development. 2-methoxyestradiol (2-ME), metabolite of 17β-estradiol (E2) and potential anticancer agent, was demonstrated to inhibit cell growth of hippocampal HT22 cells by means of nitric oxide synthase (NOS) production and oxidative stress at both pharmacologically and also physiologically relevant concentrations. Moreover, 2-ME was suggested to inhibit mitochondrial biogenesis and to be a dynamic regulator. This review is a comprehensive discussion, from both scientific and clinical point of view, about the influence of 2-ME on mitochondria and its plausible role as a modulator of neuron survival.

Glutathione peroxidase-1 and neuromodulation: Novel potentials of an old enzyme

Glutathione peroxidase (GPx) acts in co-ordination with other signaling molecules to exert its own antioxidant role. We have demonstrated the protective effects of GPx,/GPx-1, a selenium-dependent enzyme, on various neurodegenerative disorders (i.e., Parkinson's disease, Alzheimer's disease, cerebral ischemia, and convulsive disorders). In addition, we summarized the recent findings indicating that GPx-1 might play a role as a neuromodulator in neuropsychiatric conditions, such as, stress, bipolar disorder, schizophrenia, and drug intoxication. In this review, we attempted to highlight the mechanistic scenarios mediated by the GPx/GPx-1 gene in impacting these neurodegenerative and neuropsychiatric disorders, and hope to provide new insights on the therapeutic interventions against these disorders.

CUEDC2 ablation enhances the efficacy of mesenchymal stem cells in ameliorating cerebral ischemia/reperfusion insult

Mesenchymal stem cell (MSC) therapy has been reported to be a promising therapeutic option for cerebral ischemia/reperfusion (I/R) insult. However, the poor survival rate of engrafted MSCs under unfavorable cerebral I/R-induced microenvironment inhibits their efficiency during clinical application. CUE domain-containing 2(CUECD2) exhibits its protective role on cardiomyocytes by mediating the antioxidant capacity. Our study explored the functional role of CUEDC2 in cerebral I/R challenge and determined whether CUECD2-modified MSCs could improve the efficacy of treatment of the insulted neurons. We also evaluated the possible mechanisms involved in cerebral I/R condition. Cerebral I/R stimulation suppressed CUEDC2 levels in brain tissues and neurons. siRNA-CUEDC2 in neurons significantly inhibited cerebral I/R-induced apoptosis and oxidative stress levels in vitro. Moreover, siRNA-CUEDC2 in the MSCs group remarkably enhanced the therapeutic efficacies in cerebral I/R-induced neuron injury and brain tissue impairment when compared to the non-genetic MSCs treatment group. At the molecular level, siRNA-CUEDC2 in MSCs markedly enhanced its antioxidant and anti-inflammatory effect in co-cultured neurons by upregulating glutathione peroxidase 1 (GPX1) expression levels while suppressing NF-kB activation. These findings provide a novel strategy for the utilization of MSCs to promote cerebral ischemic stroke outcomes.

A novel compound DBZ ameliorates neuroinflammation in LPS-stimulated microglia and ischemic stroke rats: Role of Akt(Ser473)/GSK3β(Ser9)-mediated Nrf2 activation

Microglia-mediated neuroinflammation plays a crucial role in the pathophysiological process of multiple neurological disorders such as ischemic stroke, yet lacks effective therapeutic agents. Previously, we discovered one novel synthetic compound, tanshinol borneol ester (DBZ), possesses anti-inflammatory and anti-atherosclerotic activities, whereas little is known about its effects in CNS. Therefore, the present study aims to explore the effects and potential mechanism of DBZ on neuroinflammation and microglial function. Our studies revealed that DBZ significantly inhibited NF-κB activity, suppressed the production of pro-inflammatory mediators meanwhile promoted M2 mediators expression in LPS-stimulated BV2 cells and mouse primary microglia cells. DBZ also exhibited antioxidant activity by enhancing Nrf2 nuclear accumulation and transcriptional activity, increasing HO-1 and NQO1 expression, and inhibiting LPS-induced ROS generation in BV2 cells. Importantly, the anti-neuroinflammatory and antioxidant effects of DBZ above were reversed by Nrf2 knockdown. Additionally, DBZ ameliorated sickness behaviors of neuroinflammatory mice induced by systemic LPS administration, and significantly reduced infract volume, improved sensorimotor and cognitive function in rats subjected to transient middle cerebral artery occlusion (tMCAO); besides, DBZ restored microglia morphological alterations and shifted the M1/M2 polarization in both murine models. Mechanistically, DBZ-induced Nrf2 nuclear accumulation and antioxidant enzymes expression were accompanied by increased level of p-Akt(Ser473) (activation) and p-GSK3β(Ser9) (inactivation), and decreased nuclear level of Fyn both in vitro and in vivo. Pharmacologically inhibiting PI3K or activating GSK3β markedly increased nuclear density of Fyn in microglia cells, which blocked the promoting effect of DBZ on Nrf2 nuclear accumulation and its antioxidant and anti-neuroinflammatory activities. Collectively, these results indicated the effects of DBZ on microglia-mediated neuroinflammation were strongly associated with the nuclear accumulation and stabilization of Nrf2 via the Akt(Ser473)/GSK3β(Ser9)/Fyn pathway. With anti-neuroinflammatory and antioxidant properties, DBZ could be a promising new drug candidate for prevention and/or treatment of cerebral ischemia and other neuroinflammatory disorders.

Nuclear Factor-κB Dysregulation and α-Synuclein Pathology: Critical Interplay in the Pathogenesis of Parkinson's Disease

The loss of dopaminergic neurons of the nigrostriatal system underlies the onset of the typical motor symptoms of Parkinson's disease (PD). Lewy bodies (LB) and Lewy neurites (LN), proteinaceous inclusions mainly composed of insoluble α-synuclein (α-syn) fibrils are key neuropathological hallmarks of the brain of affected patients. Compelling evidence supports that in the early prodromal phases of PD, synaptic terminal and axonal alterations initiate and drive a retrograde degeneration process culminating with the loss of nigral dopaminergic neurons. This notwithstanding, the molecular triggers remain to be fully elucidated. Although it has been shown that α-syn fibrillary aggregation can induce early synaptic and axonal impairment and cause nigrostriatal degeneration, we still ignore how and why α-syn fibrillation begins. Nuclear factor-κB (NF-κB) transcription factors, key regulators of inflammation and apoptosis, are involved in the brain programming of systemic aging as well as in the pathogenesis of several neurodegenerative diseases. The NF-κB family of factors consists of five different subunits (c-Rel, p65/RelA, p50, RelB, and p52), which combine to form transcriptionally active dimers. Different findings point out a role of RelA in PD. Interestingly, the nuclear content of RelA is abnormally increased in nigral dopamine (DA) neurons and glial cells of PD patients. Inhibition of RelA exert neuroprotection against (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) MPTP and 1-methyl-4-phenylpyridinium (MPP+) toxicity, suggesting that this factor decreases neuronal resilience. Conversely, the c-Rel subunit can exert neuroprotective actions. We recently described that mice deficient for c-Rel develop a PD-like motor and non-motor phenotype characterized by progressive brain α-syn accumulation and early synaptic changes preceding the frank loss of nigrostriatal neurons. This evidence supports that dysregulations in this transcription factors may be involved in the onset of PD. This review highlights observations supporting a possible interplay between NF-κB dysregulation and α-syn pathology in PD, with the aim to disclose novel potential mechanisms involved in the pathogenesis of this disorder.

Total Glycosides of Cistanche deserticola Promote Neurological Function Recovery by Inducing Neurovascular Regeneration via Nrf-2/Keap-1 Pathway in MCAO/R Rats

Background

The traditional Chinese medicine Cistanche deserticola has been reported to be valid for cardiovascular and cerebrovascular diseases. However, its active components for the protection of ischemic stroke are not clear. We aimed to explore the active components of C. deserticola against ischemic stroke as well as its potential mechanisms.

Methods

We investigated the brain protective effects of extracts from C. deserticola, total glycosides (TGs), polysaccharides (PSs), and oligosaccharides (OSs) in a rat model of middle cerebral artery occlusion-reperfusion (MCAO/R). 2, 3, 5-Triphenyltetrazolium chloride (TTC) staining was used to assess the cerebral infarction volume, and Evans blue assay was adopted to assess the blood-brain barrier (BBB) permeability. Then, the expressions CD31, α-SMA, PDGFRβ, SYN, PSD95, MAP-2, ZO-1, claudin-5, occludin, Keap-1, and Nrf-2 were analyzed using western blotting or immunofluorescence, and the activities MDA, SOD, CAT, and GSH-Px were analyzed using kits.

Results

TGs treatment remarkably decreased neurological deficit scores and infarction volumes, promoted angiogenesis and neural remodeling, and effectively maintained blood-brain-barrier integrity compared with the model group. Furthermore, TGs significantly decreased MDA levels and increased antioxidant activities (SOD, CAT, and GSH-Px) in brains. Meanwhile, TGs remarkably downregulated Keap-1 expression and facilitated Nrf-2 nuclear translocation. On the contrary, no protective effects were observed for PSs and OSs groups.

Conclusion

TGs are the main active components of C. deserticola against MCAO/R-induced cerebral injury, and protection is mainly via the Nrf-2/Keap-1 pathway.

PEGylated Erythropoietin Protects against Brain Injury in the MCAO-Induced Stroke Model by Blocking NF-κB Activation

Cerebral ischemia exhibits a multiplicity of pathophysiological mechanisms. During ischemic stroke, the reactive oxygen species (ROS) concentration rises to a peak during reperfusion, possibly underlying neuronal death. Recombinant human erythropoietin (EPO) supplementation is one method of treating neurodegenerative disease by reducing the generation of ROS. We investigated the therapeutic effect of PEGylated EPO (P-EPO) on ischemic stroke. Mice were administered P-EPO (5,000 U/kg) via intravenous injection, and middle cerebral artery occlusion (MCAO) followed by reperfusion was performed to induce in vivo ischemic stroke. P-EPO ameliorated MCAO-induced neurological deficit and reduced behavioral disorder and the infarct area. Moreover, lipid peroxidation, expression of inflammatory proteins (cyclooxygenase-2 and inducible nitric oxide synthase), and cytokine levels in blood were reduced by the P-EPO treatment. In addition, higher activation of nuclear factor kappa B (NF-κB) was found in the brain after MCAO, but NF-κB activation was reduced in the P-EPO-injected group. Treatment with the NF-κB inhibitor PS-1145 (5 mg/kg) abolished the P-EPO-induced reduction of infarct volume, neuronal death, neuroinflammation, and oxidative stress. Moreover, P-EPO was more effective than EPO (5,000 U/kg) and similar to a tissue plasminogen activator (10 mg/kg). An in vitro study revealed that P-EPO (25, 50, and 100 U/mL) treatment protected against rotenone (100 nM)-induced neuronal loss, neuroinflammation, oxidative stress, and NF-κB activity. These results indicate that the administration of P-EPO exerted neuroprotective effects on cerebral ischemia damage through anti-oxidant and anti-inflammatory properties by inhibiting NF-κB activation.

Oxidative CaMKII as a potential target for inflammatory disease (Review)

CaMKII is a calcium‑activated kinase, proved to be modulated by oxidation. Currently, the oxidative activation of CaMKII exists in several models of asthma, chronic rhinosinusitis with nasal polyps, cardiovascular disease, diabetes mellitus, acute ischemic stroke and cancer. Oxidized CaMKII (ox‑CaMKII) may be important in several of these diseases. The present review examines the mechanism underlying the oxidative activation of CaMKII and summarizes the current findings associated with the function of ox‑CaMKII in inflammatory diseases. Taken together, the findings of this review aim to improve current understanding of the function of ox‑CaMKII and provide novel insights for future research.

Sodium selenite protects from 3-nitropropionic acid-induced oxidative stress in cultured primary cortical neurons

Selenium (Se) is an essential trace element for humans; its intake is needed to allow the proper synthesis of 25 different selenoproteins that are necessary to the normal functioning of several organs, including the brain. Accordingly, decreased Se levels have been associated with neurological disorders. In the present study, we investigated the potential beneficial effects of Se, as sodium selenite, against 3-nitropropionic acid (3-NP)-induced oxidative stress in primary cultures of mouse cortical neurons. 3-NP treatment caused a significant decrease in cellular viability, which was accompanied by decreases in mitochondrial complex II activity and reduced glutathione (GSH) content, as well as increases in reactive oxygen species (ROS) generation and oxidized glutathione (GSSG) levels. Sodium selenite pretreatment (6 days) attenuated 3-NP-induced decrease in cell viability. In addition, sodium selenite pretreatment significantly protected against 3-NP-induced increase in ROS generation and decrease in GSH/GSSG ratio. Of note, sodium selenite pretreatment did not change 3-NP-induced decrease of mitochondrial complex II activity, suggesting that Se modulates secondary events resultant from 3-NP-induced mitochondrial dyshomeostasis. In addition, sodium selenite pretreatment significantly increased glutathione peroxidase (GPx) activity. Our data provide insights into the mechanism of protection by sodium selenite, which is related, at least in part, to GPx induction.

Balasubramide derivative 3C modulates microglia activation via CaMKKβ-dependent AMPK/PGC-1α pathway in neuroinflammatory conditions

Neuroinflammation plays a vital role in the pathological process of cerebral ischemic stroke, but currently there is no effective treatment. After ischemia, microglia-produced proinflammatory mediator expression contributes to the aggravation of neuroinflammation, while anti-inflammatory activation of microglia develops an anti-neuroinflammatory effect via secretion of anti-inflammatory factor. Promoting the anti-inflammatory activation of microglia might be an effective treatment of stroke. Previously, we discovered one derivative of the natural product (+)-balasubramide, compound 3C, that exhibits a remarkably anti-neuroinflammatory effect in vitro with unknown mechanisms. Thus in this study, we aimed to clarify its molecular mechanisms and determine whether compound 3C has a neuroprotective effect after ischemia via regulation on microglial inflammation. We found that compound 3C promoted the anti-inflammatory mediator expression and reduced the proinflammatory mediator expression in LPS-stimulated BV2 cells and mouse primary microglia cells, which were reversed by AMP-activated protein kinase (AMPK) inhibition or AMPK upstream calmodulin-dependent protein kinase kinase beta (CaMKKβ) inhibition. Compound 3C also prevented LPS-stimulated JNK activation and enhanced PGC-1α activation in microglia, which was attenuated by AMPK inhibition. Additionally, compound 3C ameliorated depressive behaviors in LPS-induced neuroinflammatory mice by promoting the anti-inflammatory activation of microglia. Furthermore, we found that compound 3C markedly reduced brain infarct volume, improved the neurological deficit in rats with ischemia and reduced the activated microglia/macrophage cells in the ischemic area, which concomitantly enhanced the anti-inflammatory mediator expression. A mechanistic study showed that the compound 3C-mediated activation of CaMKKβ, AMPK and PGC-1α is involved in the anti-neuroinflammatory and neuroprotective effects of 3C in the brain of LPS-treated mice and ischemic rats. Taken together, our results show that compound 3C could suppress neuroinflammation in vitro and in vivo by modulating microglial activation state through the CaMKKβ-dependent AMPK/PGC-1α signaling pathway, and maybe further be developed as a promising new drug candidate for the treatment of brain disorders such as stroke associated with brain inflammation.

Selenium-Dependent Glutathione Peroxidases During Tumor Development

Five out of eight human glutathione peroxidases (GPxes) are selenoproteins and thus their expression depends on the selenium (Se) supply. Most Se-dependent GPxes are downregulated in tumor cells, while only GPx2 is considerably upregulated. Whether expression profiles of GPxes predict tumor development and patient survival is controversially discussed. Also, results from in vitro and in vivo studies modulating the expression of GPx isoforms provide evidence for both anti- and procarcinogenic mechanisms. GPxes are able to reduce hydroperoxides, which otherwise would damage DNA, possibly resulting in DNA mutations, modulate redox-sensitive signaling pathways affecting proliferation, differentiation, and cellular metabolism or initiate cell death. Considering these different processes, the role and functions of individual Se-dependent GPx isoforms will be discussed herein in the context of tumorigenesis.

Calcineurin/nuclear factor-κB signaling mediates isoflurane-induced hippocampal neuroinflammation and subsequent cognitive impairment in aged rats

It is known that inhaled anesthetics induce neuroinflammation and facilitate postoperative cognitive dysfunction (POCD) in aged individuals; however, the mechanisms by which they mediate these effects remain elusive. Inhalation of the isoflurane anesthetic leads to opening of the mitochondrial permeability transition pore and loss of mitochondrial membrane potential. Therefore, mitochondrial retrograde signaling, which is an adaptive mechanism that facilitates the transmission of signals from dysfunctional mitochondria to the nucleus to activate target gene expression, may be activated during isoflurane inhalation. Therefore, the present study was designed to investigate the role of mitochondrial retrograde signaling in isoflurane-induced hippocampal neuroinflammation and cognitive impairment in aged rats. As calcineurin (CaN) serves an important role in the initiation of mitochondrial retrograde signaling, and nuclear factor-κB (NF‑κB) is involved in CaN signaling, their effects on isoflurane‑induced hippocampal neuroinflammation and cognitive impairment were investigated. Reactive oxygen species and mitochondrial membrane potential fluorescence staining, western blotting, colorimetric analysis, ELISA, immunofluorescence and the Morris water maze test were used in the present study. The results indicate that isoflurane induced hippocampal mitochondrial dysfunction and activated CaN, which subsequently lead to the putative activation of NF‑κB. These resulted in the elevation of interleukin‑1β (IL‑1β) expression (a typical marker of neuroinflammation), and was associated with cognitive impairment in aged rats. In addition, CaN and NF‑κB inhibition attenuated isoflurane-induced neuroinflammation and subsequent cognitive impairment. In conclusion, the results of the present study demonstrate the role of mitochondrial retrograde signaling and associated protein factors in inhaled anesthetic-induced neuroinflammation and cognitive impairment. These protein factors may therefore present promising therapeutic targets for the prevention of POCD.

Upregulation of neuronal zinc finger protein A20 expression is required for electroacupuncture to attenuate the cerebral inflammatory injury mediated by the nuclear factor-kB signaling pathway in cerebral ischemia/reperfusion rats

Background

Zinc finger protein A20 (tumor necrosis factor alpha-induced protein 3) functions as a potent negative feedback inhibitor of the nuclear factor-kB (NF-kB) signaling. It exerts these effects by interrupting the activation of IkB kinase beta (IKKβ), the most critical kinase in upstream of NF-kB, and thereby controlling inflammatory homeostasis. We reported previously that electroacupuncture (EA) could effectively suppress IKKβ activation. However, the mechanism underlying these effects was unclear. Therefore, the current study further explored the effects of EA on A20 expression in rat brain and investigated the possible mechanism of A20 in anti-neuroinflammation mediated by EA using transient middle cerebral artery occlusion (MCAO) rats.

Methods

Rats were treated with EA at the “Baihui (GV20),” “Hegu (L14),” and “Taichong (Liv3)” acupoints once a day starting 2 h after focal cerebral ischemia. The spatiotemporal expression of A20, neurobehavioral scores, infarction volumes, cytokine levels, glial cell activation, and the NF-kB signaling were assessed at the indicated time points. A20 gene interference (overexpression and silencing) was used to investigate the role of A20 in mediating the neuroprotective effects of EA and in regulating the interaction between neuronal and glial cells by suppressing neuronal NF-kB signaling during cerebral ischemia/reperfusion-induced neuroinflammation.

Results

EA treatment increased A20 expression with an earlier peak and longer lasting upregulation. The upregulated A20 protein was predominantly located in neurons in the cortical zone of the ischemia/reperfusion. Furthermore, neuronal A20 cell counts were positively correlated with neurobehavioral scores but negatively correlated with infarct volume, the accumulation of pro-inflammatory cytokines, and glial cell activation. Moreover, the effects of EA on improving the neurological outcome and suppressing neuroinflammation in the brain were reversed by A20 silencing. Finally, A20 silencing also suppressed the ability of EA to inhibit neuronal NF-kB signaling pathway.

Conclusions

Ischemia/reperfusion cortical neurons in MCAO rats are the main cell types that express A20, and there is a correlation between A20 expression and the suppression of neuroinflammation and the resulting neuroprotective effects. EA upregulated neuronal A20 expression, which played an essential role in the anti-inflammatory effects of EA by suppressing the neuronal NF-kB signaling pathway in the brains of MCAO rats.

Selenium Deficiency Influences the Expression of Selenoproteins and Inflammatory Cytokines in Chicken Aorta Vessels

Selenium deficiency is known to cause cardiovascular diseases. However, the role of Se deficiency in causing oxidative damage and inflammation injury to the aorta vessels of chickens is not well known. In the present study, 180 1-day-old chickens were randomly divided into two groups, a low-Se group (L group) and a control-Se group (C group). The messenger RNA (mRNA) levels of 25 selenoproteins, the mRNA and protein expression levels of inflammatory cytokines (including NF-κB, TNF-α, COX-2, and PTGES), and the antioxidant levels in chicken aorta vessels were examined. The results showed that the mRNA levels of 25 selenoproteins and the activity of Gpx were decreased, while the mRNA and protein expression levels of inflammatory cytokines and the MDA content were increased by Se deficiency in chicken aorta vessels. The data from the present study indicated that Se deficiency decreases the expression of selenoproteins, reduces antioxidant function, and increases the expression of inflammatory factors in chicken aorta vessels.

Selenium and redox signaling

Selenium compounds that contain selenol functions or can be metabolized to selenols are toxic via superoxide and H₂O₂ generation, when ingested at dosages beyond requirement. At supra-nutritional dosages various forms of programmed cell death are observed. At physiological intakes, selenium exerts its function as constituent of selenoproteins, which overwhelmingly are oxidoreductases. Out of those, the glutathione peroxidases counteract hydroperoxide-stimulated signaling cascades comprising inflammation triggered by cytokines or lipid mediators, insulin signaling and different forms of programmed cell death. Similar events are exerted by peroxiredoxins, which functionally depend on the selenoproteins of the thioredoxin reductase family. The thiol peroxidases of both families can, however, also act as sensors for hydroperoxides, thereby initiating signaling cascades. Although the interaction of selenoproteins with signaling events has been established by genetic techniques, the in vivo relevance of these findings is still hard to delineate for several reasons: The biosynthesis of individual selenoproteins responds differently to variations of selenium intakes; selenium is preferentially delivered to privileged tissues via inter-organ trafficking and receptor-mediated uptake, and only half of the selenoproteins known by sequence have been functionally characterized. The fragmentary insights do not allow any uncritical use of selenium for optimizing human health.

Nafamostat mesilate improves function recovery after stroke by inhibiting neuroinflammation in rats

Inflammation plays an important role in stroke pathology, making it a promising target for stroke intervention. Nafamostat mesilate (NM), a wide-spectrum serine protease inhibitor, is commonly used for treating inflammatory diseases, such as pancreatitis. However, its effect on neuroinflammation after stroke was unknown. Hence, the effects of NM on the inflammatory response post stroke were characterized. After transient middle cerebral artery occlusion (tMCAO) in rats, NM reduced the infarct size, improved behavioral functions, decreased the expression of proinflammatory mediators (TNF-α, IL-1β, iNOS and COX-2) in a time-dependent manner and promoted the expression of different anti-inflammatory factors (CD206, TGF-β, IL-10 and IL-4) at different time points. Furthermore, NM could inhibit the expression of proinflammatory mediators and promote anti-inflammatory mediators expression in rat primary microglia following exposure to thrombin combined with oxygen-glucose deprivation (OGD). The immune-modulatory effect of NM might be partly due to its inhibition of the NF-κB signaling pathway and inflammasome activation after tMCAO. In addition, NM significantly inhibited the infiltration of macrophage, neutrophil and T lymphocytes, which was partly mediated by the inhibition of monocyte chemotactic protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Taken together, our results indicated that NM can provide long-term protection of the brain against tMCAO by modulating a broad components of the inflammatory response.

Protein methionine oxidation augments reperfusion injury in acute ischemic stroke

Reperfusion injury can exacerbate tissue damage in ischemic stroke, but little is known about the mechanisms linking ROS to stroke severity. Here, we tested the hypothesis that protein methionine oxidation potentiates NF-κB activation and contributes to cerebral ischemia/reperfusion injury. We found that overexpression of methionine sulfoxide reductase A (MsrA), an antioxidant enzyme that reverses protein methionine oxidation, attenuated ROS-augmented NF-κB activation in endothelial cells, in part, by protecting against the oxidation of methionine residues in the regulatory domain of calcium/calmodulin-dependent protein kinase II (CaMKII). In a murine model, MsrA deficiency resulted in increased NF-κB activation and neutrophil infiltration, larger infarct volumes, and more severe neurological impairment after transient cerebral ischemia/reperfusion injury. This phenotype was prevented by inhibition of NF-κB or CaMKII. MsrA-deficient mice also exhibited enhanced leukocyte rolling and upregulation of E-selectin, an endothelial NF-κB-dependent adhesion molecule known to contribute to neurovascular inflammation in ischemic stroke. Finally, bone marrow transplantation experiments demonstrated that the neuroprotective effect was mediated by MsrA expressed in nonhematopoietic cells. These findings suggest that protein methionine oxidation in nonmyeloid cells is a key mechanism of postischemic oxidative injury mediated by NF-κB activation, leading to neutrophil recruitment and neurovascular inflammation in acute ischemic stroke.

NF-kappaB Signaling Pathways in Neurological Inflammation: A Mini Review

The NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells) transcription factor family is a pleiotropic regulator of many cellular signaling pathways, providing a mechanism for the cells in response to a wide variety of stimuli linking to inflammation. The stimulated cells will be regulated by not only the canonical but also non-canonical NF-κB pathways. To initiate both of these pathways, IκB-degradation triggers NF-κB release and the nuclear translocated-heterodimer (or homodimer) can associate with the κB sites of promoter to regulate the gene transcriptions. NF-κB ubiquitously expresses in neurons and the constitutive NF-κB activation is associated with processing of neuronal information. NF-κB can regulate the transcription of genes such as chemokines, cytokines, proinflammatory enzymes, adhesion molecules, proinflammatory transcription factors, and other factors to modulate the neuronal survival. In neuronal insult, NF-κB constitutively active in neuron cell bodies can protect neurons against different injuries and regulate the neuronal inflammatory reactions. Besides neurons, NF-κB transcription factors are abundant in glial cells and cerebral blood vessels and the diverse functions of NF-κB also regulate the inflammatory reaction around the neuronal environment. NF-κB transcription factors are abundant in the brain and exhibit diverse functions. Several central nerve system (CNS) diseases are linked to NF-κB activated by inflammatory mediators. The RelA and c-Rel expression produce opposite effects on neuronal survival. Importantly, c-Rel expression in CNS plays a critical role in anti-apoptosis and reduces the age-related behaviors. Moreover, the different subunits of NF-κB dimer formation can modulate the neuroninflammation, neuronal protection, or neurotoxicity. The diverse functions of NF-κB depend on the subunits of the NF-κB dimer-formation which enable us to develop a therapeutic approach to neuroinflammation based on a new concept of inflammation as a strategic tool in neuronal cells. However, the detail role of NF-κB in neuroinflammation, remains to be clarified. In the present article, we provide an updated review of the current state of our knowledge about relationship between NF-κB and neuroinflammation.

Superoxide dismutase 1 and glutathione peroxidase 1 are involved in the protective effect of sulodexide on vascular endothelial cells exposed to oxygen-glucose deprivation

Sulodexide (SDX) is widely used in the treatment of both arterial and venous thrombotic disorders. In addition to its recognized antithrombotic action, SDX has endothelial protective potential, which is independent of the coagulation/fibrinolysis system. However, the detailed molecular mechanisms of the endothelioprotective action of the drug are still unresolved. The aim of the present study was to determine whether treatment with SDX at concentrations of 0.125-0.5 lipase releasing unit (LRU)/ml have on the expression and activity of antioxidant enzymes in ischemic endothelial cells and how these effects might be related to the antiapoptotic properties of SDX. In the present study, human umbilical vein endothelial cells (HUVECs) were subjected to ischemia-simulating conditions (combined oxygen and glucose deprivation, OGD) for 6h to determine the protective effects of SDX. SDX (0.25 and 0.5LRU/ml) in OGD significantly increased the cell viability and prevented mitochondrial depolarization in the HUVECs. Moreover, SDX protected the HUVECs against OGD-induced apoptosis. At concentrations of 0.25 and 0.5LRU/ml, the drug increased both superoxide dismutase 1 (SOD1) and glutathione peroxidase 1 (GPx1) mRNA/protein expression together with a significant attenuation of oxidative stress in ischemic HUVECs. Our findings also demonstrate that an increase in both SOD and GPx activity is involved in the protective effect of SDX on ischemic endothelial cells. Altogether, these results suggest that SDX has a positive effect on ischemia-induced endothelial damage because of its antioxidant and antiapoptotic properties.

Octreotide Protects the Mouse Retina against Ischemic Reperfusion Injury through Regulation of Antioxidation and Activation of NF-κB

Somatostatin (SST), an endogenous peptide, may exert anti-inflammatory and neuroprotective effects on retinal injury induced by ischemia. Retinal ischemic reperfusion (I/R) injury always produces many reactive oxygen species (ROS), which can aggravate the tissue damage. The effects of octreotide (OCT), a SST analogue, on retinal I/R injury and ROS formation, are not very clear. In this study, we observed the effects of OCT on morphological changes, oxidative stress, and cell death, induced by retinal I/R injury. The activation of nuclear factor κB (NF-κB) and intercellular adhesion molecule-1 (ICAM-1) were further evaluated in I/R retina treated with or without OCT. The retinal layer thickness was increased at 1 day after I/R and decreased at 7 days after I/R (P < 0.05). This effect was associated with increase in MDA and ROS levels (P < 0.05). The Tunel-positive cells increased and the number of ganglion cell layer (GCL) neurons decreased significantly after I/R injury. The expression of p-p65 and ICAM-1 increased significantly in I/R retinas (P < 0.05). Each effect was markedly attenuated by application of OCT. These data indicate that OCT protects the retina against retinal I/R damage, which could be through inhibition of oxidative stress and downregulation of NF-κB and ICAM-1 expression.

NF-κB in Innate Neuroprotection and Age-Related Neurodegenerative Diseases

NF-κB factors are cardinal transcriptional regulators of inflammation and apoptosis, involved in the brain programing of systemic aging and in brain damage. The composition of NF-κB active dimers and epigenetic mechanisms modulating histone acetylation, finely condition neuronal resilience to brain insults. In stroke models, the activation of NF-κB/c-Rel promotes neuroprotective effects by transcription of specific anti-apoptotic genes. Conversely, aberrant activation of NF-κB/RelA showing reduced level of total acetylation, but site-specific acetylation on lysine 310, triggers the expression of pro-apoptotic genes. Constitutive knockout of c-Rel shatters the resilience of substantia nigra (SN) dopaminergic (DA) neurons to aging and induces a parkinsonian like pathology in mice. c-rel(-/-) mice show increased level of aberrantly acetylated RelA in the basal ganglia, neuroinflammation, accumulation of alpha-synuclein, and iron. Moreover, they develop motor deficits responsive to l-DOPA treatment and associated with loss of DA neurons in the SN. Here, we discuss the effect of unbalanced activation of RelA and c-Rel during aging and propose novel challenges for the development of therapeutic strategies in neurodegenerative diseases.

Involvement of the Antioxidant Effect and Anti-inflammatory Response in Butyrate-Inhibited Vascular Smooth Muscle Cell Proliferation

Epigenetic mechanisms by altering the expression and, in turn, functions of target genes have potential to modify cellular processes that are characteristics of atherosclerosis, including inflammation, proliferation, migration and apoptosis/cell death. Butyrate, a natural epigenetic modifier and a histone deacetylase inhibitor (HDACi), is an inhibitor of vascular smooth muscle cell (VSMC) proliferation, a critical event in atherogenesis. Here, we examined whether glutathione peroxidases (GPxs), a family of antioxidant enzymes, are modulated by butyrate, contributing to its antiproliferation action on VSMC through the regulation of the inflammatory response by using western blotting, immunostaining methods and activity assay. Treatment of VSMC with butyrate not only upregulates glutathione peroxidase (GPx) 3 and GPx4, but also increases the overall catalytic activity of GPx supporting involvement of antioxidant effect in butyrate arrested VSMC proliferation. Moreover, analysis of the redox-sensitive NF-κB transcription factor system, the target of GPx, reveals that butyrate causes downregulation of IKKα, IKKβ, IkBα and NF-κBp65 expression and prevents NF-κBp65 phosphorylation at serine536 causing inhibition of the expression NF-κB target inflammatory genes, including inducible nitric oxide synthase, VCAM-1 and cyclooxygenase-2. Overall, these observations suggest a link between the antioxidant effect and anti-inflammatory response in butyrate-arrested VSMC proliferation, accentuating the atheroprotective and therapeutic potential of natural products, like butyrate, in vascular proliferative diseases.

Enriched endogenous omega-3 fatty acids in mice protect against global ischemia injury

Transient global cerebral ischemia, one of the consequences of cardiac arrest and cardiovascular surgery, usually leads to delayed death of hippocampal cornu Ammonis1 (CA1) neurons and cognitive deficits. Currently, there are no effective preventions or treatments for this condition. Omega-3 (ω-3) PUFAs have been shown to have therapeutic potential in a variety of neurological disorders. Here, we report that the transgenic mice that express the fat-1 gene encoding for ω-3 fatty acid desaturase, which leads to an increase in endogenous ω-3 PUFAs and a concomitant decrease in ω-6 PUFAs, were protected from global cerebral ischemia injury. The results of the study show that the hippocampal CA1 neuronal loss and cognitive deficits induced by global ischemia insult were significantly less severe in fat-1 mice than in WT mice controls. The protection against global cerebral ischemia injury was closely correlated with increased production of resolvin D1, suppressed nuclear factor-kappa B activation, and reduced generation of pro-inflammatory mediators in the hippocampus of fat-1 mice compared with WT mice controls. Our study demonstrates that fat-1 mice with high endogenous ω-3 PUFAs exhibit protective effects on hippocampal CA1 neurons and cognitive functions in a global ischemia injury model.

Antioxidant gene therapy against neuronal cell death

Oxidative stress is a common hallmark of neuronal cell death associated with neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, as well as brain stroke/ischemia and traumatic brain injury. Increased accumulation of reactive species of both oxygen (ROS) and nitrogen (RNS) has been implicated in mitochondrial dysfunction, energy impairment, alterations in metal homeostasis and accumulation of aggregated proteins observed in neurodegenerative disorders, which lead to the activation/modulation of cell death mechanisms that include apoptotic, necrotic and autophagic pathways. Thus, the design of novel antioxidant strategies to selectively target oxidative stress and redox imbalance might represent important therapeutic approaches against neurological disorders. This work reviews the evidence demonstrating the ability of genetically encoded antioxidant systems to selectively counteract neuronal cell loss in neurodegenerative diseases and ischemic brain damage. Because gene therapy approaches to treat inherited and acquired disorders offer many unique advantages over conventional therapeutic approaches, we discussed basic research/clinical evidence and the potential of virus-mediated gene delivery techniques for antioxidant gene therapy.

Evidence that collaboration between HIF-1α and Notch-1 promotes neuronal cell death in ischemic stroke

Recent findings suggest that Notch-1 signaling contributes to neuronal death in ischemic stroke, but the underlying mechanisms are unknown. Hypoxia inducible factor-1α (HIF-1α), a global regulator of cellular responses to hypoxia, can interact with Notch and modulate its signaling during hypoxic stress. Here we show that Notch signaling interacts with the HIF-1α pathway in the process of ischemic neuronal death. We found that a chemical inhibitor of the Notch-activating enzyme, γ-secretase, and a HIF-1α inhibitor, protect cultured cortical neurons against ischemic stress, and combined inhibition of Notch-1 and HIF-1α further decreased neuronal death. HIF-1α and Notch intracellular domain (NICD) are co-expressed in the neuronal nucleus, and co-immunoprecipitated in cultured neurons and in brain tissue from mice subjected to focal ischemic stroke. Overexpression of NICD and HIF-1α in cultured human neural cells enhanced cell death under ischemia-like conditions, and a HIF-1α inhibitor rescued the cells. RNA interference-mediated depletion of endogenous NICD and HIF-1α also decreased cell death under ischemia-like conditions. Finally, mice treated with inhibitors of γ-secretase and HIF-1α exhibited improved outcome after focal ischemic stroke, with combined treatment being superior to individual treatments. Additional findings suggest that the NICD and HIF-1α collaborate to engage pro-inflammatory and apoptotic signaling pathways in stroke.

Gemfibrozil pretreatment affecting antioxidant defense system and inflammatory, but not Nrf-2 signaling pathways resulted in female neuroprotection and male neurotoxicity in the rat models of global cerebral ischemia-reperfusion

Two important pathophysiological mechanisms involved during cerebral ischemia are oxidative stress and inflammation. In pathological conditions such as brain ischemia the ability of free radicals production is greater than that of elimination by endogenous antioxidative systems, so brain is highly injured due to oxidation and neuroinflammation. Fibrates as peroxisome proliferator-activated receptor (PPAR)-α ligands, are reported to have antioxidant and anti-inflammatory actions. In this study, gemfibrozil, a fibrate is investigated for its therapeutic potential against global cerebral ischemia-reperfusion (I/R) injury of male and female rats. This study particularly has focused on inflammatory and antioxidant signaling pathways, such as nuclear factor erythroid-related factor (Nrf)-2, as well as the activity of some endogenous antioxidant agents. It was found that pretreatment of animals with gemfibrozil prior to I/R resulted in a sexually dimorphic outcome. Within females it proved to be protective, modulating inflammatory factors and inducing antioxidant defense system including superoxide dismutase (SOD), catalase, as well as glutathione level. However, Nrf-2 signaling pathway was not affected. It also decreased malondialdehyde level as an index of lipid peroxidation. In contrast, gemfibrozil pretreatment was toxic to males, enhancing the expression of inflammatory factors such as tumor necrosis factor-α, nuclear factor-κB, and cyclooxygenase-2, and decreasing Nrf-2 expression and SOD activity, leading to hippocampal neurodegeneration. Considering that gemfibrozil is a commonly used anti-hyperlipidemic agent in clinic, undoubtedly more investigations are crucial to exactly unravel its sex-dependent neuroprotective/neurodegenerative potential.

Activation of nuclear factor-κB in the brain after experimental subarachnoid hemorrhage and its potential role in delayed brain injury

It has been reported that inflammation is involved in brain injury after subarachnoid hemorrhage (SAH). Nuclear factor-κB (NF-κB) is a key transcriptional regulator of inflammatory genes. Here, we used pyrrolidine dithiocarbamate(PDTC), an inhibitor of NF-κB, through intracisternal injection to study the role of NF-κB in delayed brain injury after SAH. A total of 55 rabbits were randomly divided into five groups: the control group; the SAH groups including Day-3, 5, and 7 SAH groups (the rabbits in these groups were sacrificed at 3, 5, 7 days after SAH, respectively); and the PDTC group (n = 11 for each group). Electrophoretic mobility shift assay (EMSA) was performed to detect NF-κB DNA-binding activity. The mRNA levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and intercellular adhesion molecule (ICAM)-1 were evaluated by RT-PCR analysis. Deoxyribonucleic acid fragmentation was detected by TUNEL and p65 immunoactivity was assessed by immunohistochemistry. Our results showed the activation of NF-κB after SAH, especially at day 3 and 5. The activated p65 was detected in neurons. NF-κB DNA-binding activity was suppressed by intracisternal administration of PDTC. Increased levels of the TNF-α, IL-1β, and ICAM-1 mRNA were found in the brain at day 5 after SAH, and which were suppressed in the PDTC group. The number of TUNEL-positive cells also decreased significantly in the PDTC group compared with that in the Day-5 SAH group. These results demonstrated that the activated NF-κB in neurons after SAH plays an important role in regulating the expressions of inflammatory genes in the brain, and ultimately contributes to delayed brain injury.

Redox regulation of mitochondrial function

Redox-dependent processes influence most cellular functions, such as differentiation, proliferation, and apoptosis. Mitochondria are at the center of these processes, as mitochondria both generate reactive oxygen species (ROS) that drive redox-sensitive events and respond to ROS-mediated changes in the cellular redox state. In this review, we examine the regulation of cellular ROS, their modes of production and removal, and the redox-sensitive targets that are modified by their flux. In particular, we focus on the actions of redox-sensitive targets that alter mitochondrial function and the role of these redox modifications on metabolism, mitochondrial biogenesis, receptor-mediated signaling, and apoptotic pathways. We also consider the role of mitochondria in modulating these pathways, and discuss how redox-dependent events may contribute to pathobiology by altering mitochondrial function.

NF-κB and epigenetic mechanisms as integrative regulators of brain resilience to anoxic stress

Brain cells display an amazing ability to respond to several different types of environmental stimuli and integrate this response physiologically. Some of these responses can outlive the original stimulus by days, weeks or even longer. Long-lasting changes in both physiological and pathological conditions occurring in response to external stimuli are almost always mediated by changes in gene expression. To effect these changes, cells have developed an impressive repertoire of signaling systems designed to modulate the activity of numerous transcription factors and epigenetic mechanisms affecting the chromatin structure. Since its initial characterization in the nervous system, NF-κB has shown to respond to multiple signals and elicit pleiotropic activities suggesting that it may play a pivotal role in integration of different types of information within the brain. Ample evidence demonstrates that NF-κB factors are engaged in and necessary for neuronal development and synaptic plasticity, but they also regulate brain response to environmental noxae. By focusing on the complexity of NF-κB transcriptional activity in neuronal cell death, it emerged that the composition of NF-κB active dimers finely tunes the neuronal vulnerability to brain ischemia. Even though we are only beginning to understand the contribution of distinct NF-κB family members to the regulation of gene transcription in the brain, an additional level of regulation of NF-κB activity has emerged as operated by the epigenetic mechanisms modulating histone acetylation. We will discuss NF-κB and epigenetic mechanisms as integrative regulators of brain resilience to anoxic stress and useful drug targets for restoration of brain function. This article is part of a Special Issue entitled: Brain Integration.

Glutathione peroxidase-1 deficiency augments proinflammatory cytokine-induced redox signaling and human endothelial cell activation

Glutathione peroxidase-1 (GPx-1) is a crucial antioxidant enzyme, the deficiency of which promotes atherogenesis. Accordingly, we examined the mechanisms by which GPx-1 deficiency enhances endothelial cell activation and inflammation. In human microvascular endothelial cells, we found that GPx-1 deficiency augments intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression by redox-dependent mechanisms that involve NFκB. Suppression of GPx-1 enhanced TNF-α-induced ROS production and ICAM-1 expression, whereas overexpression of GPx-1 attenuated these TNF-α-mediated responses. GPx-1 deficiency prolonged TNF-α-induced IκBα degradation and activation of ERK1/2 and JNK. JNK or NFκB inhibition attenuated TNF-α induction of ICAM-1 and VCAM-1 expression in GPx-1-deficient and control cells, whereas ERK1/2 inhibition attenuated only VCAM-1 expression. To analyze further signaling pathways involved in GPx-1-mediated protection from TNF-α-induced ROS, we performed microarray analysis of human microvascular endothelial cells treated with TNF-α in the presence and absence of GPx-1. Among the genes whose expression changed significantly, dual specificity phosphatase 4 (DUSP4), encoding an antagonist of MAPK signaling, was down-regulated by GPx-1 suppression. Targeted DUSP4 knockdown enhanced TNF-α-mediated ERK1/2 pathway activation and resulted in increased adhesion molecule expression, indicating that GPx-1 deficiency may augment TNF-α-mediated events, in part, by regulating DUSP4.

Neuroprotection from retinal ischemia/reperfusion injury by NOX2 NADPH oxidase deletion

PURPOSE

The aim of this study was to determine whether NOX2, one of the homologs of NADPH oxidase, plays a role in neuronal cell death during retinal ischemia.

METHODS

Ischemia reperfusion (I/R) injury was generated in C57/BL6 and NOX2(-/-) mice by increasing the intraocular pressure (IOP) to 110 mm Hg for 40 minutes followed by reperfusion. Quantitative PCR and Western blot analysis were performed to measure NOX2 expression. Reactive oxygen species (ROS) formation was assessed by dihydroethidium imaging of superoxide formation and Western blot analysis for tyrosine nitration. TUNEL assay was performed to determine cell death at 3 days after I/R. Survival of neurons within the ganglion cell layer (GCL) was assessed at 7 days after I/R by confocal morphometric imaging of retinal wholemounts immunostained with NeuN antibody. Activation of mitogen-activated protein kinases and nuclear factor κB (NF-κΒ) was measured by Western blot analysis.

RESULTS

NOX2 mRNA and protein and ROS were significantly increased in wild-type I/R retinas. This effect was associated with a 60% decrease in the number of GCL neurons and a 10-fold increase in TUNEL-positive cells compared with the fellow sham control eyes. Phosphorylation of ERK and NF-κB was significantly increased in wild-type I/R retinas. Each of these effects was markedly attenuated in the NOX2(-/-) retina (P < 0.01).

CONCLUSIONS

These data demonstrate that the deletion of NOX2 can reduce I/R-induced cell death and preserve retinal GCL neurons after I/R injury. The neuronal cell injury caused by I/R is associated with the activation of ERK and NF-κB signaling mechanisms.