SOD1 down-regulates NF-kappaB and c-Myc expression in mice after transient focal cerebral ischemia

Increased stress vulnerability in the offspring of socially isolated rats: Behavioural, neurochemical and redox dysfunctions

Stressful events during pregnancy impact on the progeny neurodevelopment. However, little is known about preconceptional stress effects. The rat social isolation represents an animal model of chronic stress inducing a variety of dysfunctions. Moreover, social deprivation during adolescence interferes with key neurodevelopmental processes. Here, we investigated the development of behavioural, neurochemical and redox alterations in the male offspring of socially isolated female rats before pregnancy, reared in group (GRP) or in social isolation (ISO) from weaning until young-adulthood. To this aim, females were reared in GRP or in ISO conditions, from PND21 to PND70, when they were mated. Their male offspring was housed in GRP or ISO conditions through adolescence and until PND70, when passive avoidance-PA, novel object recognition-NOR and open field-OF tests were performed. Levels of noradrenaline (NA), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), glutamate (GLU) and GABA were assessed in the prefrontal cortex (PFC). Moreover, cortical ROS levels were quantified, as well as NF-kB and the NADPH oxidase NOX2 expression, redox status (expressed as GSH:GSSG ratio) and SOD1 amount. A significant decrease of the latency time in the PA was observed in the offspring of ISO females. In the NOR test, while a significant increase in the exploratory activity towards the novel object was observed in the offspring of GRP females, no significant differences were found in the offspring of ISO females. No significant differences were found in the OF test among experimental groups. Theoffspring of ISO females showed increased NA and 5-HIAA levels, whereas in the offspring persistently housed in isolation condition from weaninguntil adulthood, we detected reduced 5-HT levels and ehnanced 5-HIAA amount. No significant changes in GLU concentrations were detected, while decreased GABA content was observed in the offspring of ISO females exposed to social isolation. Increased ROS levels as well as reduced NF-κB, NOX2 expression were detected in the offspring of ISO females. This was accompanied by reduced redox status and enhanced SOD1 levels. In conclusion, our results suggest that female exposure to chronic social stress before pregnancy might have a profound influence on the offspring neurodevelopment in terms of cognitive, neurochemical and redox-related alterations, identifying this specific time window for possible preventive and therapeutic strategies.

Exercise ameliorates skeletal muscle insulin resistance by modulating GRK4-mediated D1R expression

Exercise has been recommended as a nonpharmaceutical therapy to treat insulin resistance (IR). Previous studies showed that dopamine D1-like receptor agonists, such as fenoldopam, could improve peripheral insulin sensitivity, while antipsychotics, which are dopamine receptor antagonists, increased susceptibility to Type 2 diabetes mellitus (T2DM). Meanwhile, exercise has been proved to stimulate dopamine receptors. However, whether the dopamine D1 receptor (D1R) is involved in exercise-mediated amelioration of IR remains unclear. We found that the D1-like receptor antagonist, SCH23390, reduced the effect of exercise on lowering blood glucose and insulin in insulin-resistant mice and inhibited the contraction-induced glucose uptake in C2C12 myotubes. Similarly, the opposite was true for the D1-like receptor agonist, fenoldopam. Furthermore, the expression of D1R was decreased in skeletal muscles from streptozotocin (STZ)- and high-fat intake-induced T2DM mice, accompanied by increased D1R phosphorylation, which was reversed by exercise. A screening study showed that G protein-coupled receptor kinase 4 (GRK4) may be the candidate kinase for the regulation of D1R function, because, in addition to the increased GRK4 expression in skeletal muscles of T2DM mice, GRK4 transgenic T2DM mice exhibited lower insulin sensitivity, accompanied by higher D1R phosphorylation than control mice, whereas the AAV9-shGRK4 mice were much more sensitive to insulin than AAV9-null mice. Mechanistically, the up-regulation of GRK4 expression caused by increased reactive oxygen species (ROS) in IR was ascribed to the enhanced expression of c-Myc, a transcriptional factor of GRK4. Taken together, the present study shows that exercise, via regulation of ROS/c-Myc/GRK4 pathway, ameliorates D1R dysfunction and improves insulin sensitivity.

Neonatal asphyxia as an inflammatory disease: Reactive oxygen species and cytokines

Neonatologists resuscitate asphyxiated neonates by every available means, including positive ventilation, oxygen therapy, and drugs. Asphyxiated neonates sometimes present symptoms that mimic those of inflammation, such as fever and edema. The main pathophysiology of the asphyxia is inflammation caused by hypoxic-ischemic reperfusion. At birth or in the perinatal period, neonates may suffer several, hypoxic insults, which can activate inflammatory cells and inflammatory mediator production leading to the release of larger quantities of reactive oxygen species (ROS). This in turn triggers the production of oxygen stress-induced high mobility group box-1 (HMGB-1), an endogenous damage-associated molecular patterns (DAMPs) protein bound to toll-like receptor (TLR) -4, which activates nuclear factor-kappa B (NF-κB), resulting in the production of excess inflammatory mediators. ROS and inflammatory mediators are produced not only in activated inflammatory cells but also in non-immune cells, such as endothelial cells. Hypothermia inhibits pro-inflammatory mediators. A combination therapy of hypothermia and medications, such as erythropoietin and melatonin, is attracting attention now. These medications have both anti-oxidant and anti-inflammatory effects. As the inflammatory response and oxidative stress play a critical role in the pathophysiology of neonatal asphyxia, these drugs may contribute to improving patient outcomes.

Microglial inflammatory reactions regulated by oxidative stress

Microglia are immune cells in the brain that can respond to endogenous and exogenous substrates to elicit inflammatory reactions. The transcription factor nuclear factor kappa-light-chain-enhancer of activated B induces proinflammatory gene expression in response to foreign matter via pattern recognition receptors; thus, nuclear factor kappa-light-chain-enhancer of activated B is a master regulator of inflammation. During the inflammatory process, very large amounts of reactive oxygen species are generated and promote the onset and progression of inflammation. Interestingly, nuclear factor kappa-light-chain-enhancer of activated B drives the transcription of superoxide dismutase 2 in many types of cells, including microglia. Superoxide dismutase 2 is an antioxidative enzyme that catalyzes the dismutation of superoxide anions into molecular oxygen and hydrogen peroxide. Of note, nuclear factor kappa-light-chain-enhancer of activated B can initiate inflammation to elicit proinflammatory gene expression, while its transcription product superoxide dismutase 2 can suppress inflammation. In this review, we use recent knowledge to describe the interaction between oxidative stress and nuclear factor kappa-light-chain-enhancer of activated B and discuss the complicated role of microglial superoxide dismutase 2 in inflammation.

Cellular prion protein offers neuroprotection in astrocytes submitted to amyloid β oligomer toxicity

The cellular prion protein (PrP^C), in its native conformation, performs numerous cellular and cognitive functions in brain tissue. However, despite the cellular prion research in recent years, there are still questions about its participation in oxidative and neurodegenerative processes. This study aims to elucidate the involvement of PrP^C in the neuroprotection cascade in the presence of oxidative stressors. For that, astrocytes from wild-type mice and knockout to PrP^C were subjected to the induction of oxidative stress with hydrogen peroxide (H₂O₂) and with the toxic oligomer of the amyloid β protein (AβO). We observed that the presence of PrP^C showed resistance in the cell viability of astrocytes. It was also possible to monitor changes in basic levels of metals and associate them with an induced damage condition, indicating the precise role of PrP^C in metal homeostasis, where the absence of PrP^C leads to metallic unbalance, culminating in cellular vulnerability to oxidative stress. Increased caspase 3, p-Tau, p53, and Bcl2 may establish a relationship between a PrP^C and an induced damage condition. Complementarily, it has been shown that PrP^C prevents the internalization of AβO and promotes its degradation under oxidative stress induction, thus preventing protein aggregation in astrocytes. It was also observed that the presence of PrP^C can be related to translocating SOD1 to cell nuclei under oxidative stress, probably controlling DNA damage. The results of this study suggest that PrP^C acts against oxidative stress activating the cellular response and defense by displaying neuroprotection to neurons and ensuring the functionality of astrocytes.

Downregulation of miR-23b by transcription factor c-Myc alleviates ischemic brain injury by upregulating Nrf2

Ischemic brain injury (IBI) is a common acute cerebral vessel disease that occurs secondary to blockage in arteries, mainly characterized by insufficient blood supply to the brain. The transcription factor c-Myc in IBI continues to be implicated in numerous studies. This study was conducted with emphasis placed on the underlying mechanism of c-Myc in IBI. Clinical samples were collected from IBI patients. Middle cerebral artery occlusion (MCAO) was induced in mice by inserting a suture from the external carotid artery to the anterior cerebral artery through the internal carotid artery to mechanically block the blood supply at the origin of the middle cerebral artery, and cortical neurons from mice were exposed to oxygen glucose deprivation (OGD) conditions for IBI model in vitro construction. RT-qPCR was performed to determine microRNA-23b (miR-23b) expression. TUNEL staining and Western blot analysis was conducted to detect apoptosis. The regulatory relationship was analyzed by dual-luciferase reporter gene assay. After loss- and gain-of-function assays, triphenyltetrazolium chloride staining was carried out to detect the area of cerebral infarction, after which the spatial memory in mice was evaluated with Morris water maze test. As per our findings, miR-23b was upregulated in the serum of IBI patients and OGD-treated murine primary neurons. Silencing of miR-23b resulted in reduced OGD-induced neuronal apoptosis. miR-23b inversely targeted nuclear factor erythroid 2-related factor 2 (Nrf2) and c-Myc negatively regulated miR-23b expression. Overexpression of c-Myc and inhibition of miR-23b led to reduced neurological scores of infarction area, neuronal apoptosis, shortened platform arrival time and significantly increased the time spent on the platform quadrant and the times of crossing the platform in vivo. Collectively, downregulated miR-23b by c-Myc might alleviate IBI by upregulating Nrf2.

Curcumin Prevents Brain Damage and Cognitive Dysfunction During Ischemic-reperfusion Through the Regulation of miR-7-5p

OBJECTIVE

This study was to investigate the potential protective effects of curcumin in cerebral ischemia-reperfusion (CIR) and its regulation of miR-7.

METHODS

Rats were occluded by middle cerebral artery occlusion (MCAO) for 1.5 h and reperfused for 2 h to establish a local CIR model. After 24 hours of model establishment, MCAO rats were given curcumin for 3 days by intragastric administration. PC12 cells were cultured for 6 h in oxygen-glucose deprivation medium and then reoxygenated for 24 h to establish an oxygenglucose deprivation/reoxygenation (OGD/R) model. The OGD/R model cells were treated with curcumin for 48 h.

RESULTS

Curcumin inhibited the decrease of miR-7-5p expression and an increase of RelA p65 expression induced by CIR and ODG/R. RelA p65 was a target of miR-7-5p. MiR-7-5p antagonists were able to counteract the effect of curcumin on the expression of RelA p65 in ischemic brain tissue of MCAO rats and OGD/R model cells. Curcumin improved OGD/R-induced inhibition of cell activity, necrosis and apoptosis. Curcumin significantly reduced the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, reactive oxygen species (ROS) and malondialdehyde (MDA) and increased the activity of superoxide dismutases (SOD) and catalase (CAT) in OGD/R-induced cells. Curcumin may inhibit OGD/R-induced cell damage by regulating miR-7-5p. Curcumin improved cerebral infarction, nerve damage and cognitive dysfunction in rats with CIR, which may be related to the regulation of miR-7-5p/RelA p65 axis.

CONCLUSION

Curcumin exerts cerebral protection by attenuating cell necrosis and apoptosis, inflammatory response and oxidative stress following CIR, which may be related to its regulation of the miR-7/RELA p65 axis.

Peroxynitrite promotes serine-62 phosphorylation-dependent stabilization of the oncoprotein c-Myc

Stabilization of c-Myc oncoprotein is dependent on post-translational modifications, especially its phosphorylation at serine-62 (S62), which enhances its tumorigenic potential. Herein we report that increase in intracellular superoxide induces phospho-stabilization and activation of c-Myc in cancer cells. Importantly, sustained phospho-S62 c-Myc was necessary for promoting superoxide dependent chemoresistance as non-phosphorylatable S62A c-Myc was insensitive to the redox impact when subjected to chemotherapeutic insults. This redox-dependent sustained S62 phosphorylation occurs through nitrative inhibition of phosphatase, PP2A, brought about by peroxynitrite, a reaction product of superoxide and nitric oxide. We identified a conserved tyrosine residue (Y238) in the c-Myc targeting subunit B56α of PP2A, which is selectively amenable to nitrative inhibition, further preventing holoenzyme assembly. In summary, we have established a novel mechanism wherein the pro-oxidant microenvironment stimulates a pro-survival milieu and reinforces tumor maintenance as a functional consequence of c-Myc activation through its sustained S62 phosphorylation via inhibition of phosphatase PP2A.

Significance statement

Increased peroxynitrite signaling in tumors causes sustained S62 c-Myc phosphorylation by PP2A inhibition. This is critical to promoting c-Myc stabilization and activation which promotes chemoresistance and provides significant proliferative and growth advantages to osteosarcomas.

Investigation of the underlying hub genes and mechanisms of reperfusion injury in patients undergoing coronary artery bypass graft surgery by integrated bioinformatic analyses

Background

Although coronary artery bypass graft (CABG) surgery is the main method to revascularize the occluded coronary vessels in coronary artery diseases, the full benefits of the operation are mitigated by ischemia-reperfusion (IR) injury. Although many studies have been devoted to reducing IR injury in animal models, the translation of this research into the clinical field has been disappointing. Our study aimed to explore the underlying hub genes and mechanisms of IR injury.

Methods

A weighted gene co-expression network analysis (WGCNA) was executed based on the expression profiles in patients undergoing CABG surgery (GSE29396). Functional annotation and protein-protein interaction (PPI) network construction were executed within the modules of interest. Potential hub genes were predicted, combining both intramodular connectivity (IC) and degrees. Meanwhile, potential transcription factors (TFs) and microRNAs (miRNAs) were predicted by corresponding bioinformatics tools.

Results

A total of 336 differentially expressed genes (DEGs) were identified. DEGs were mainly enriched in neutrophil activity and immune response. Within the modules of interest, 5 upregulated hub genes (IL-6, CXCL8, IL-1β, MYC, PTGS-2) and 6 downregulated hub genes (C3, TIMP1, VSIG4, SERPING1, CD163, and HP) were predicted. Predicted miRNAs (hsa-miR-333-5p, hsa-miR-26b-5p, hsa-miR-124-3p, hsa-miR-16-5p, hsa-miR-98-5p, hsa-miR-17-5p, hsa-miR-93-5p) and TF (STAT1) might have regulated gene expression in the most positively related module, while hsa-miR-333-5p and HSF-1 were predicted to regulate the genes within the most negatively related module.

Conclusions

Our study illustrates an overview of gene expression changes in human atrial samples from patients undergoing CABG surgery and might help translate future research into clinical work.

Identification of proteins potentially associated with renal aging in rats

We established a young (Y)-old (O) rat kidney transplantation model. With this model, we detected no age-related differences in renal structure between Y→Y and Y→O kidneys or O→O and O→Y kidneys. However, we did detect differences in levels of the senescence markers β-gal and p16 as well as the inflammatory cytokines TNF-α and IL-1β. Using proteomics analysis we detected 66 proteins associated with suppression of aging and 73 proteins associated with enhancement of aging. After construction of a protein-protein interaction network, a total of 73 nodes and 99 edges were analyzed using MCODE, and three significant modules were selected. GO and KEGG analyses showed that these proteins were mainly located in mitochondria and were largely related to oxidative stress. Among them, SOD1 expression was lower in Y→O than Y→Y kidneys and higher in O→Y than O→O kidneys. Acetylated (Ac)-NF-κB showed the opposite expression profile. In addition, SOD1 expression was higher in primary tubular epithelial cells from young rats than old rats, and SOD1 knockdown led to increased Ac-NF-κB expression. These findings suggest the local renal environment, particularly oxidative stress/mitochondrial function, affects renal aging.

Role of GluN2A NMDA receptor in homocysteine-induced prostaglandin E2 release from neurons

Hyperhomocysteinemia or systemic elevation of homocysteine is a metabolic condition that has been linked to multiple neurological disorders where inflammation plays an important role in the progression of the disease. However, it is unclear whether hyperhomocysteinemia contributes to disease pathology by inducing an inflammatory response. The current study investigates whether exposure of primary cultures from rat and mice cortical neurons to high levels of homocysteine induces the expression and release of the proinflammatory prostanoid, Prostaglandin E2 (PGE2). Using enzymatic assays and immunoblot analysis we show concurrent increase in the activity of cytosolic phospholipase A2 (cPLA2) and level of cyclooxygenase-2 (COX2), two enzymes involved in PGE2 biosynthesis. The findings also show an increase in PGE2 release from neurons. Pharmacological inhibition of GluN2A-containing NMDAR (GluN2A-NMDAR) with NVP-AAM077 significantly reduces homocysteine-induced cPLA2 activity, COX2 expression, and subsequent PGE2 release. Whereas, inhibition of GluN2B-containing NMDAR (GluN2A-NMDAR) with Ro 25-6981 has no effect. Complementary studies in neuron cultures obtained from wild type and GluN2A knockout mice show that genetic deletion of GluN2A subunit of NMDAR attenuates homocysteine-induced neuronal increase in cPLA2 activity, COX2 expression, and PGE2 release. Pharmacological studies further establish the role of both extracellular-regulated kinase/mitogen-activated protein kinase and p38 MAPK in homocysteine-GluN2A NMDAR-dependent activation of cPLA2-COX2-PGE2 pathway. Collectively, these findings reveal a novel role of GluN2A-NMDAR in facilitating homocysteine-induced proinflammatory response in neurons.

Peptides from Cauliflower By-Products, Obtained by an Efficient, Ecosustainable, and Semi-Industrial Method, Exert Protective Effects on Endothelial Function

The large amount of cauliflower industry waste represents an unexplored source of bioactive compounds. In this work, peptide hydrolysates from cauliflower leaves were characterized by combined bioanalytical approaches. Twelve peptide fractions were studied to evaluate unexplored biological activities by effect-based cellular bioassays. A potent inhibition of intracellular xanthine oxidase activity was observed in human vascular endothelial cells treated with one fraction, with an IC50 = 8.3 ± 0.6 μg/ml. A different fraction significantly induced the antioxidant enzyme superoxide dismutase 1 and decreased the tumor necrosis factor α-induced VCAM-1 expression, thus leading to a significant improvement in the viability of human vascular endothelial cells. Shotgun peptidomics and bioinformatics were used to retrieve the most probable bioactive peptide sequences. Our study shows that peptides from cauliflower waste should be recycled for producing valuable products useful for the prevention of endothelial dysfunction linked to atherogenesis progression.

Prophylactic Zinc and Therapeutic Selenium Administration Increases the Antioxidant Enzyme Activity in the Rat Temporoparietal Cortex and Improves Memory after a Transient Hypoxia-Ischemia

In the cerebral hypoxia-ischemia rat model, the prophylactic administration of zinc can cause either cytotoxicity or preconditioning effect, whereas the therapeutic administration of selenium decreases the ischemic damage. Herein, we aimed to explore whether supplementation of low doses of prophylactic zinc and therapeutic selenium could protect from a transient hypoxic-ischemic event. We administrated zinc (0.2 mg/kg of body weight; ip) daily for 14 days before a 10 min common carotid artery occlusion (CCAO). After CCAO, we administrated sodium selenite (6 μg/kg of body weight; ip) daily for 7 days. In the temporoparietal cerebral cortex, we determined nitrites by the Griess method and lipid peroxidation by the Gerard-Monnier assay. qPCR was used to measure mRNA of nitric oxide synthases, antioxidant enzymes, chemokines, and their receptors. We measured the enzymatic activity of SOD and GPx and protein levels of chemokines and their receptors by ELISA. We evaluated long-term memory using the Morris-Water maze test. Our results showed that prophylactic administration of zinc caused a preconditioning effect, decreasing nitrosative/oxidative stress and increasing GPx and SOD expression and activity, as well as eNOS expression. The therapeutic administration of selenium maintained this preconditioning effect up to the late phase of hypoxia-ischemia. Ccl2, Ccr2, Cxcl12, and Cxcr4 were upregulated, and long-term memory was improved. Pyknotic cells were decreased suggesting prevention of neuronal cell death. Our results show that the prophylactic zinc and therapeutic selenium administration induces effective neuroprotection in the early and late phases after CCAO.

Long-Term Exposure of Fine Particulate Matter Causes Hypertension by Impaired Renal D1 Receptor-Mediated Sodium Excretion via Upregulation of G-Protein-Coupled Receptor Kinase Type 4 Expression in Sprague-Dawley Rats

BACKGROUND

Epidemiological evidence supports an important association between air pollution exposure and hypertension. However, the mechanisms are not clear.

METHODS AND RESULTS

Our present study found that long-term exposure to fine particulate matter (PM2.5) causes hypertension and impairs renal sodium excretion, which might be ascribed to lower D1 receptor expression and higher D1 receptor phosphorylation, accompanied with a higher G-protein-coupled receptor kinase type 4 (GRK4) expression. The in vivo results were confirmed in in vitro studies (ie, PM2.5 increased basal and decreased D1 receptor mediated inhibitory effect on Na+-K+ ATPase activity, decreased D1 receptor expression, and increased D1 receptor phosphorylation in renal proximal tubule cells). The downregulation of D1 receptor expression and function might be attributable to a higher GRK4 expression after the exposure of renal proximal tubule cells to PM2.5, because downregulation of GRK4 by small-interfering RNA reversed the D1 receptor expression and function. Because of the role of reactive oxygen species on D1 receptor dysfunction and its relationship with air pollution exposure, we determined plasma reactive oxygen species and found the levels higher in PM2.5-treated Sprague-Dawley rats. Inhibition of reactive oxygen species by tempol (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl) reduced blood pressure and increased sodium excretion in PM2.5-treated Sprague-Dawley rats, accompanied by an increase in the low D1 receptor expression, and decreased the hyperphosphorylated D1 receptor and GRK4 expression.

CONCLUSIONS

Our present study indicated that long-term exposure of PM2.5 increases blood pressure by decreasing D1 receptor expression and function; reactive oxygen species, via regulation of GRK4 expression, plays an important role in the pathogenesis of PM2.5-induced hypertension.

Ginkgolides and bilobalide protect BV2 microglia cells against OGD/reoxygenation injury by inhibiting TLR2/4 signaling pathways

Ginkgolide and bilobalide are major trilactone constituent of Ginkgo biloba leaves and have been shown to exert powerful neuroprotective properties. The aims of this study were to observe the inhibitory effects of ginkgolide and bilobalide on the activation of microglial cells induced by oxygen-glucose deprivation and reoxygenation (OGD/R) and the specific mechanisms by which these effects are mediated. For detecting whether ginkgolide and bilobalide increased cell viability in a dose-dependent manner, BV2 cells were subjected to oxygen-glucose deprivation for 4 h followed by 3 h reoxygenation with various concentrations of drugs (6.25, 12.5, 25, 50, and 100 μg/ml). The extent of apoptosis effect of OGD/R with or without ginkgolide and bilobalide treatment were also measured by Annexin V-FITC/PI staining. Similarly, the levels of pro-inflammatory cytokines TNF-α, IL-1β, IL-6, IL-8, and IL-10 were detected using a specific Bio-Plex Pro™ Reagent Kit. The effects of ginkgolide and bilobalide on protein levels of TLR2/4, MyD88, p-TAK1, p-IKKβ, p-IkBα, NF-κB p65, Bcl-2, Bax, Bak, RIP3, cleaved-Caspase-3, cleaved PARP-1 and cellular localization of NF-κB p65 were evaluated by Western blot and double-labeled immunofluorescence staining, respectively. OGD/R significantly decreased the cell viability and increased the release of IL-1β, IL-6, IL-8, IL-10, TNF-α in BV2 microglia cells; these effects were suppressed by ginkgolide and bilobalide. Meanwhile, ginkgolide and bilobalide also attenuated the OGD/R-induced increases in TLR2, TLR4, MyD88, Bak, RIP3 levels and reversed cleaved caspase-3/caspase-3, Bax/Bcl-2 and cleaved PARP-1/PARP-1 ratio. Furthermore, ginkgolide and bilobalide also downregulated p-TAK1, p-IkBα, and p-IKKβ and inhibited the OGD/R-induced transfer of NF-κB p65 from cytoplasm to nucleus in BV2 microglia cells. The results showed that ginkgolide and bilobalide can inhibit OGD/R-induced production of inflammatory factors in BV2 microglia cells by regulating the TLRs/MyD88/NF-κB signaling pathways and attenuating inflammatory response. The possible mechanism of anti-inflammatory and neuroprotective effects of ginkgolides results from the synergistic reaction among each monomer constituents.

Effects of simvastatin and taurine on delayed cerebral vasospasm following subarachnoid hemorrhage in rabbits

The aim of the current study was to observe the effects of simvastatin and taurine on delayed cerebral vasospasm (DCVS) following experimental subarachnoid hemorrhage (SAH) in rabbits. A total of 48 New Zealand white rabbits were allocated at random into four groups (control, SAH, SAH + simvastatin and SAH + taurine groups; n=12 each). The rabbit model of DCVS was established using a double hemorrhage method, which involved injecting autologous arterial blood into the cisterna magna in the SAH groups. The SAH + simvastatin group was administered oral simvastatin (5 mg/kg) daily between days 0-6. The SAH + taurine group was administered oral taurine (50 mg/kg) daily between days 0-6. Starch (50 mg/kg) was administered orally to the animals in the other two groups (control and SAH groups). The control group were not subjected to any other injections or treatment. The internal diameter and internal diameter/wall thickness of the basilar artery (BA) were measured. The expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were determined using immunohistochemical and quantitative polymerase chain reaction methods following the sacrifice of all animals on day 7. The activity of nuclear factor (NF)-κB in the BA was also measured using an electrophoretic mobility shift assay. The BA walls in the SAH + simvastatin and SAH + taurine groups exhibited reduced narrowing and corrugation of the tunica elastica interna compared with the SAH group. At the protein and cDNA levels, it was found that cerebral vasospasm of the BA in the SAH + simvastatin and SAH + taurine groups was alleviated, as indicated by the reduced expression of TNF-α, IL-1β, IL-6 and NF-κB compared with the SAH group (P<0.05). In conclusion, simvastatin and taurine reduced DCVS following SAH in rabbits, which suggests that these compounds may exert anti-inflammatory effects.

Increased vascular MMP-9 in mice lacking RNF213: moyamoya disease susceptibility gene

Moyamoya disease (MMD) is a chronic occlusive cerebrovascular disease with unknown etiology. Recent genetic studies have identified RNF213 as an important susceptibility gene for MMD. To evaluate the role of RNF213 in vascular remodeling, RNF213 knockout mice (RNF213-/-) and their wild-type littermates (WT) were subjected to common carotid artery ligation to induce vascular hyperplasia. We examined the vascular expression of matrix metalloproteinase (MMP)-9, known to be increased in MMD. MMP-9 expression was significantly higher in RNF213-/- mice than in wild-type mice 1 and 7 days after common carotid artery ligation. The vascular wall was significantly thinner in RNF213-/- mice at 14 days. The increased vascular expression of MMP-9 and subsequent vascular wall thinning in RNF213-/- mice could reflect the early characteristic of MMD, consistent with the recently proposed constrictive remodeling theory.

Effects of ROS-relative NF-κB signaling on high glucose-induced TLR4 and MCP-1 expression in podocyte injury

High glucose (HG) induced inflammation is central to progression in diabetic nephropathy (DN). Recent studies have suggested that nuclear factor-kappa B (NF-κB) signaling activation is associated with DN, and podocyte damage may be involved in orchestrating these effects. Therefore, the aim of this study was to investigate the effects of NF-κB signaling on podocytes under HG conditions. The effects of HG and NF-κB signaling on podocytes were assessed by CCK-8 assay, cellular NF-κB translocation assay, measurement of reactive oxygen species (ROS) and Western blot analysis. We found that HG reduced cell viability, activated NF-κB signaling and up-regulated toll-like receptor 4 (TLR4) and monocyte chemoattractant protein-1 (MCP-1). In these cells, NF-κB inhibition with ammonium pyrrolidinethiocarbamate (PDTC) resulted in effectively constraining TLR4 and MCP-1 up-regulation, indicating that protective effects associated with the inhibition of NF-κB were linked to TLR4 and MCP-1 down-regulation in podocytes. Furthermore, HG significantly increased the production of intracellular ROS. Pretreatment with N-acetyl-l-cysteine (NAC) significantly inhibited intracellular ROS generation and increased cell viability, accompanied by a significant NF-κB inhibition and suppression of TLR4 and inflammatory cytokine MCP-1 expression. Collectively, our novel data suggest that HG induces the over-experssion of TLR-4 and MCP-1 through a NF-κB-dependent signaling. NF-κB-mediated increased inflammation is possibly via ROS and contributes to the cell injury. These results may provide potential therapeutic target for diabetic nephropathy in the future.

Anti-inflammatory and antiapoptotic effects of mesenchymal stem cells transplantation in rat brain with cerebral ischemia

BACKGROUND

Excessive inflammation and apoptosis contribute to the pathogenesis of ischemic brain damage. Nuclear factor-kappa B (NF-κB) is considered to be a key protein complex involved in this cascade of events. The aim of the present study was to clarify the protection mechanism of the mesenchymal stem cells (MSCs).

METHODS

Lewis rats (N = 90) were randomly assigned to three groups: (1) the sham-operated group; (2) the saline group, in which the animals underwent rat transient middle cerebral artery occlusion (tMCAO, for 2 hours) and were treated with saline through the tail vein; and (3) the MSCs group, in which the animals underwent tMCAO (for 2 hours) and were infused with cultured human MSCs (4 × 10(6)/0.4 ml PBS) through the tail vein. At days 1 and 3 post-MSCs infusion, real-time PCR, and Western blot, immunohistochemical analyses were applied for tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and P-IKKβ, p53, and B-cell lymphoma 2 (Bcl-2) expression levels.

RESULTS

TNF-α, IL-1β messenger RNA (mRNA) and P-IκB-α, P-IKKβ, p53 protein expression levels were significantly increased in the saline group compared with the sham group. However, IκB-α and Bcl-2 protein expression levels were markedly decreased in the saline group. After injection of BrdU(+) MSCs, the expression levels of TNF-α, IL-1β mRNA and P-IκB-α, P-IKKβ, p53 protein were significantly decreased. Contrary to these findings, IκB-α, Bcl-2 protein expression levels were markedly increased. In addition, we found that infarct area was significantly reduced in MSCs group.

CONCLUSIONS

These results suggest that MSCs' neuroprotection is attributable to its anti-inflammatory and antiapoptotic effect through inhibition of NF-κB.

Buyang Huanwu Decoction fraction protects against cerebral ischemia/reperfusion injury by attenuating the inflammatory response and cellular apoptosis

Buyang Huanwu Decoction fraction extracted from Buyang Huanwu Decoction contains saponins of Astragalus, total paeony glycoside and safflower flavones. The aim of this study was to demonstrate the neuroprotective effect and mechanism of Buyang Huanwu Decoction fraction on ischemic injury both in vivo and in vitro. In vivo experiments showed that 50-200 mg/kg Buyang Huanwu Decoction fraction reduced infarct volume and pathological injury in ischemia/reperfusion rats, markedly inhibited expression of nuclear factor-κB and tumor necrosis factor-α and promoted nestin protein expression in brain tissue. Buyang Huanwu Decoction fraction (200 mg/kg) exhibited significant effects, which were similar to those of 100 mg/kg Ginkgo biloba extract. In vitro experimental results demonstrated that 10-100 mg/L Buyang Huanwu Decoction fraction significantly improved cell viability, decreased the release of lactate dehydrogenase and malondialdehyde levels, and inhibited the rate of apoptosis in HT22 cells following oxygen-glucose deprivation. Buyang Huanwu Decoction fraction (100 mg/L) exhibited significant effects, which were similar to those of 100 mg/L Ginkgo biloba extract. These findings suggest that Buyang Huanwu Decoction fraction may represent a novel, protective strategy against cerebral ischemia/reperfusion injury in rats and oxygen-glucose deprivation-induced damage in HT22 cells in vitro by attenuating the inflammatory response and cellular apoptosis.

Atg5 deficiency-mediated mitophagy aggravates cardiac inflammation and injury in response to angiotensin II

OBJECTIVE

Hypertension induces end-organ damage through inflammation, and autophagy plays a crucial role in the regulation of cellular homeostasis. In the present study, we aimed to define the role of autophagy in the development of inflammation and cardiac injury induced by angiotensin II (Ang II).

METHODS AND RESULTS

Autophagy protein 5 (Atg5) haplodeficiency (Atg5(+/-)) and age-matched wild-type (WT) C57BL/6J mice were infused with Ang II (1500 ng/kg/min) or saline for 7 days. Heart sections were stained with hematoxylin and eosin (H&E), Masson's trichrome, and immunohistochemical stains. Cytokine and LC3 levels were measured using real-time PCR or western blot analysis. After Ang II infusion, the WT mice exhibited marked macrophage accumulation, cytokine expression, and reactive oxygen species (ROS) production compared with saline-infused controls. However, these effects induced by Ang II infusion were aggravated in Atg5(+/-) mice. These effects were associated with Atg5-mediated impaired autophagy, accompanied by increased production of ROS and activation of nuclear factor-κB (NF-κB) in macrophages. Finally, increased cardiac inflammation in Atg5 haplodeficient mice was associated with increased cardiac fibrosis.

CONCLUSION

Atg5 deficiency-mediated autophagy increases ROS production and NF-κB activity in macrophages, thereby contributing to cardiac inflammation and injury. Thus, improving autophagy may be a novel therapeutic strategy to ameliorate hypertension-induced inflammation and organ damage.

Intracranial injection of recombinant stromal-derived factor-1 alpha (SDF-1α) attenuates traumatic brain injury in rats

OBJECTIVE

This study was conducted to investigate the role of stromal-derived factor-1 alpha (SDF-1α) in a secondary brain injury after traumatic brain injury (TBI) in rats, and to further elucidate its underlying regulatory mechanisms.

MATERIALS AND METHODS

Male Sprague-Dawley rats underwent TBI for 30 min, and then received intracranial injections of recombinant SDF-1α, SDF-1α antibody, or saline as a vehicle control. At 24 h after TBI, brain tissues from the experimental animals were subjected to histology, immunohistochemistry, quantitative real-time polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and western blot analyses.

RESULTS

TBI-induced brain edema and blood-brain barrier disruption were ameliorated by post-injury injections of SDF-1α. TBI-induced neuronal degradation and apoptosis, accompanied by increased cleaved caspase-3, cleaved PARP and Bax, and decreased Bcl-2 were found to be attenuated by SDF-1α injection. Nitric oxide (NO) and inducible nitric oxide synthase (iNOS) levels decreased in SDF-1α treated animals after TBI. SDF-1α repressed inflammatory responses by inhibiting the expression of pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6. However, neutralizing the effect of SDF-1α with its antibody abolished these therapeutic alterations in TBI animals. Importantly, SDF-1α attenuated the brain lesion by affecting the ERK and NF-κB signaling pathways after mechanical head trauma in rats.

CONCLUSIONS

SDF-1α ameliorates mechanical trauma-induced pathological changes via its anti-apoptotic and anti-inflammatory action in the brain.

Activation of the p38 MAPK/NF-κB pathway contributes to doxorubicin-induced inflammation and cytotoxicity in H9c2 cardiac cells

A number of studies have demonstrated that inflammation plays a role in doxorubicin (DOX)-induced cardiotoxicity. However, the molecular mechanism by which DOX induces cardiac inflammation has yet to be fully elucidated. The present study aimed to investigate the role of the p38 mitogen-activated protein kinase (MAPK)/nuclear factor-κB (NF-κB) pathway in DOX-induced inflammation and cytotoxicity. The results of our study demonstrated that the exposure of H9c2 cardiac cells to DOX reduced cell viability and stimulated an inflammatory response, as demonstrated by an increase in the levels of interleukin-1β (IL-1β) and IL-6, as well as tumor necrosis factor-α (TNF-α) production. Notably, DOX exposure induced the overexpression of phosphorylated p38 MAPK and phosphorylation of the NF-κB p65 subunit, which was markedly inhibited by SB203580, a specific inhibitor of p38 MAPK. The inhibition of NF-κB by pyrrolidine dithiocarbamate (PDTC), a selective inhibitor of NF-κB, significantly ameliorated DOX-induced inflammation, leading to a decrease in the levels of IL-1β and IL-6, as well as TNF-α production in H9c2 cells. The pretreatment of H9c2 cells with either SB203580 or PDTC before exposure to DOX significantly attenuated DOX-induced cytotoxicity. In conclusion, our study provides novel data demonstrating that the p38 MAPK/NF-κB pathway is important in the induction of DOX-induced inflammation and cytotoxicity in H9c2 cardiac myocytes.

Nitric oxide donors as neuroprotective agents after an ischemic stroke-related inflammatory reaction

Cerebral ischemia initiates a cascade of detrimental events including glutamate-associated excitotoxicity, intracellular calcium accumulation, formation of Reactive oxygen species (ROS), membrane lipid degradation, and DNA damage, which lead to the disruption of cellular homeostasis and structural damage of ischemic brain tissue. Cerebral ischemia also triggers acute inflammation, which exacerbates primary brain damage. Therefore, reducing oxidative stress (OS) and downregulating the inflammatory response are options that merit consideration as potential therapeutic targets for ischemic stroke. Consequently, agents capable of modulating both elements will constitute promising therapeutic solutions because clinically effective neuroprotectants have not yet been discovered and no specific therapy for stroke is available to date. Because of their ability to modulate both oxidative stress and the inflammatory response, much attention has been focused on the role of nitric oxide donors (NOD) as neuroprotective agents in the pathophysiology of cerebral ischemia-reperfusion injury. Given their short therapeutic window, NOD appears to be appropriate for use during neurosurgical procedures involving transient arterial occlusions, or in very early treatment of acute ischemic stroke, and also possibly as complementary treatment for neurodegenerative diseases such as Parkinson or Alzheimer, where oxidative stress is an important promoter of damage. In the present paper, we focus on the role of NOD as possible neuroprotective therapeutic agents for ischemia/reperfusion treatment.

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.

20-Hydroxyecdysone protects against oxidative stress-induced neuronal injury by scavenging free radicals and modulating NF-κB and JNK pathways

Oxidative stress plays an important role in the pathological processes of ischemic brain damage. Many antioxidants have been shown to protect against cerebral ischemia injury by inhibiting oxidative stress both in vitro and in vivo. 20-Hydroxyecdysone (20E), an ecdysteroid hormone, exhibits antioxidative effects. For the work described in this paper, we used an in vitro oxidative damage model and an in vivo ischemic model of middle cerebral artery occlusion (MCAO) to investigate the neuroprotective effects of 20E and the mechanisms related to these effects. Treatment of cells with H₂O₂ led to neuronal injury, intracellular ROS/RNS generation, mitochondrial membrane potential dissipation, cellular antioxidant potential descent, an increase in malondialdehyde (MDA) and an elevation of intracellular [Ca²⁺], all of which were markedly attenuated by 20E. Inhibition of the activation of the ASK1-MKK4/7-JNK stress signaling pathway and cleaved caspase-3 induced by oxidative stress were involved in the neuroprotection afforded by 20E. In addition, 20E reduced the expression of iNOS protein by inhibition of NF-κB activation. The neuroprotective effect of 20E was also confirmed in vivo. 20E significantly decreased infarct volume and the neurological deficit score, restored antioxidant potential and inhibited the increase in MDA and TUNEL-positive and cleaved caspase-3-positive cells in the cerebral cortex in MCAO rats. Together, these results support that 20E protects against cerebral ischemia injury by inhibiting ROS/RNS production and modulating oxidative stress-induced signal transduction pathways.

Modulation of Preactivation of PPAR-β on Memory and Learning Dysfunction and Inflammatory Response in the Hippocampus in Rats Exposed to Global Cerebral Ischemia/Reperfusion

The aim of this study is to investigate the neuroprotective effects and relevant mechanism of GW0742, an agonist of PPAR-β, after global cerebral ischemia-reperfusion injury (GCIRI) in rats. The rats showed memory and cognitive impairment and cytomorphological change in the hippocampus neurons following GCIRI. These effects were significantly improved by pretreatment with GW0742 in the dose-dependent manner. The expressions of IL-1β, IL-6, and TNF-α were increased after GCIRI, while the increases in these proinflammatory cytokines by GCIRI were inhibited by GW0742 pretreatment. Similarly, GW0742 pretreatment also improved the GCIRI-induced decrease in the expression of IL-10, which can act as an inhibitory cytokine to reduce cerebral ischemic injury. For another, NF-κB p65 expression was significantly increased in hippocampal neurons with apparent nuclear translocation after global cerebral IRI, and these phenomena were also largely attenuated by GW0742 pretreatment. Moreover, the mRNA and protein expressions of PPAR-β were significantly decreased in GCIRI + GW0742 groups when compared with those in GCIRI group. Our data suggests that the PPAR-β agonist GW0742 can exert significant neuroprotective effect against GCIRI in rats via PPAR-β activation and its anti-inflammation effect mediated by the inhibition of expression and activation of NF-κB in the hippocampus.

Cathepsin S deficiency results in abnormal accumulation of autophagosomes in macrophages and enhances Ang II-induced cardiac inflammation

BACKGROUND

Cathepsin S (Cat S) is overexpressed in human atherosclerotic and aneurysmal tissues and may contributes to degradation of extracellular matrix, especially elastin, in inflammatory diseases. We aimed to define the role of Cat S in cardiac inflammation and fibrosis induced by angiotensin II (Ang II) in mice.

METHODS AND RESULTS

Cat S-knockout (Cat S(-/-)) and littermate wild-type (WT) C57BL/6J mice were infused continuously with Ang II (750 ng/kg/min) or saline for 7 days. Cat S(-/-) mice showed severe cardiac fibrosis, including elevated expression of collagen I and α-smooth muscle actin (α-SMA), as compared with WT mice. Moreover, macrophage infiltration and expression of inflammatory cytokines (tumor necrosis factor α, transforming growth factor β and interleukin 1β) were significantly greater in Cat S(-/-) than WT hearts. These Ang II-induced effects in Cat S(-/-) mouse hearts was associated with abnormal accumulation of autophagosomes and reduced clearance of damaged mitochondria, which led to increased levels of reactive oxygen species (ROS) and activation of nuclear factor-kappa B (NF-κB) in macrophages.

CONCLUSION

Cat S in lysosomes is essential for mitophagy processing in macrophages, deficiency in Cat S can increase damaged mitochondria and elevate ROS levels and NF-κB activity in hypertensive mice, so it regulates cardiac inflammation and fibrosis.

Salvianolic acid A protects human SH-SY5Y neuroblastoma cells against H₂O₂-induced injury by increasing stress tolerance ability

Salvianolic acid A (Sal A) is a polyphenol extracted from the root of the Salvia miltiorrhiza bunge. Hydrogen peroxide (H(2)O(2)) is a major reactive oxygen species (ROS), which has been implicated in stroke and other neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. In this study, we investigated the neuroprotective effects of Sal A in human SH-SY5Y neuroblastoma cells against H(2)O(2)-induced injury. Our results showed that cells pretreated with Sal A exhibited enhanced neuronal survival and that this protection was associated with an increase in adenosine triphosphate (ATP) and the stabilization of mitochondrial membrane potential. In addition, Sal A markedly decreased the excessive activation AMP-activated protein kinase (AMPK) and the serine-threonine protein kinase, Akt, in SH-SY5Ycells induced by H(2)O(2). In conclusion, our results demonstrated that Sal A protects SH-SY5Y cells against H(2)O(2)-induced oxidative stress and these protective effects are related to stress tolerance and not energy depletion via inhibition of the AMPK and Akt signaling pathway.

Direct protection of neurons and astrocytes by matrine via inhibition of the NF-κB signaling pathway contributes to neuroprotection against focal cerebral ischemia

Matrine (Mat) and oxymatrine are two major alkaloids of the Chinese herb Sophora flavescens Ait. (Leguminosae). Previous study has demonstrated that Mat reduces brain edema induced by focal cerebral ischemia. More recently, oxymatrine has been reported to produce neuroprotective effects against focal cerebral ischemia via inhibiting the activation of NF-κB in the ischemic brain tissue. In the current study, we investigated whether direct protection on neurons and astrocytes via inhibition of NF-κB signaling pathway is associated with Mat's neuroprotective effects against cerebral ischemia. In a model of permanent middle cerebral artery occlusion (pMCAO), Mat (12.5, 25 and 50 mg/kg) reduced the infarction volume and improved the neurological deficits in a dose-dependent manner, administered 10 min, 3h and even 6h following pMCAO. Mat 50 mg/kg also decreased the hemispheric water content. The number of GFAP-positive cells was markedly decreased in the ischemic cortex at 12h after ischemia. In contrast, Mat increased the number of GFAP-positive cells. Mat 50mg/kg has no effect on the cerebral blood flow (CBF). Primary neuron or astrocyte cultures were exposed to a paradigm of ischemic insult by using an oxygen-glucose deprivation (OGD), Mat (50-200 μM) reduced LDH leakage and the number of neuronal and astrocytic apoptosis, and increased the number of MAP2-positive and GFAP-positive cells. Further observations revealed that Mat increased the protein levels of IκBα, and blocked the translocation of NF-κB p65 from the cytosol to the nucleus in the ischemic cortex and injured neurons and astrocytes induced by in vitro OGD. Moreover, Mat could down-regulate NF-κB p65 downstream pro-apoptotic gene p53 and/or c-Myc in the injured neurons and astrocytes induced by OGD. The present findings suggest that Mat, even when administrated 6h after ischemia, has neuroprotective effects against focal cerebral ischemia and directly protects neurons and astrocytes via inhibition of NF-κB signaling pathway, contributing to matrine's neuroprotection against focal cerebral ischemia.

ER stress in retinal degeneration in S334ter Rho rats

The S334ter rhodopsin (Rho) rat (line 4) bears the rhodopsin gene with an early termination codon at residue 334 that is a model for several such mutations found in human patients with autosomal dominant retinitis pigmentosa (ADRP). The Unfolded Protein Response (UPR) is implicated in the pathophysiology of several retinal disorders including ADRP in P23H Rho rats. The aim of this study was to examine the onset of UPR gene expression in S334ter Rho retinas to determine if UPR is activated in ADRP animal models and to investigate how the activation of UPR molecules leads to the final demise of S334ter Rho photoreceptors. RT-PCR was performed to evaluate the gene expression profiles for the P10, P12, P15, and P21 stages of the development and progression of ADRP in S334ter Rho photoreceptors. We determined that during the P12–P15 period, ER stress-related genes are strongly upregulated in transgenic retinas, resulting in the activation of the UPR that was confirmed using western blot analysis and RT-PCR. The activation of UPR was associated with the increased expression of JNK, Bik, Bim, Bid, Noxa, and Puma genes and cleavage of caspase-12 that together with activated calpains presumably compromise the integrity of the mitochondrial MPTP, leading to the release of pro-apoptotic AIF1 into the cytosol of S334ter Rho photoreceptor cells. Therefore, two major cross-talking pathways, the UPR and mitochondrial MPTP occur in S334ter-4 Rho retina concomitantly and eventually promote the death of the photoreceptor cells.

Recent progress in histochemistry and cell biology

Studies published in Histochemistry and Cell Biology in the year 2011 represent once more a manifest of established and newly sophisticated techniques being exploited to put tissue- and cell type-specific molecules into a functional context. The review is therefore the Histochemistry and Cell Biology's yearly intention to provide interested readers appropriate summaries of investigations touching the areas of tissue biology, developmental biology, the biology of the immune system, stem cell research, the biology of subcellular compartments, in order to put the message of such studies into natural scientific-/human- and also pathological-relevant correlations.

Ammonia increases paracellular permeability of rat brain endothelial cells by a mechanism encompassing oxidative/nitrosative stress and activation of matrix metalloproteinases

Ammonia is responsible for cerebral edema associated with acute liver failure, but the role of the vasogenic mechanism has been a matter of dispute. Here, we tested the hypothesis that ammonia induces changes in blood-brain barrier (BBB) permeability by a mechanism coupled to oxidative/nitrosative stress (ONS) evoked in the BBB-forming cerebral capillary endothelial cells. Treatment of a rat brain endothelial cell line with ammonia (5 mmol/L, 24 h) caused accumulation of ONS markers: reactive oxygen species, nitric oxide and peroxidation products of phospholipid-bound arachidonic acid, F2-isoprostanes. Concurrently, ammonia increased the activity of extracellular matrix metalloproteinases (MMP-2/MMP-9), increased cell permeability to fluorescein isothiocyanate-dextran (40 kDa), and increased the expression of y+LAT2, a transporter that mediates the uptake to the cells of the nitric oxide precursor, arginine. The increase of cell permeability was ameliorated upon co-treatment with a MMP inhibitor, SB-3CT and with an antioxidant, glutathione diethyl ester, which also reduced F2-isoprostanes. Ammonia-induced ONS was attenuated by cytoprotective agents l-ornithine, phenylbutyrate, and their conjugate l-ornithine phenylbutyrate, an ammonia-trapping drug used to treat hyperammonemia. The results support the concept that ONS and ONS-related activation of MMPs in cerebral capillary endothelial cells contribute to the alterations in BBB permeability and to the vasogenic component of cerebral edema associated with acute liver failure.

Therapeutic potential of c-Myc inhibition in the treatment of hypertrophic cardiomyopathy

Investigating the pathophysiological importance of the molecular and mechanical development of cardiomyopathy is critical to find new and broader means of protection against this disease that is increasing in prevalence and impact. The current available treatment options for cardiomyopathy mainly focus on treating symptoms and strive to make the patient more comfortable while preventing progression of disease and sudden death. The proto-oncogene c-Myc (Myc) has been shown to be increased in many different types of heart disease, including hypertrophic cardiomyopathy, before any signs of the disease are present. As the mechanisms of action and multiple pathways of dependent actions of Myc are being dissected by many research groups, inhibition of Myc is becoming an attractive paradigm for prevention and treatment of cardiomyopathy and heart failure. Elucidating the role Myc plays in the development, propagation and perpetuation of cardiomyopathy and heart failure will one day translate into potential therapeutics for cardiomyopathy.

Oxidative stress and blood-brain barrier dysfunction under particular consideration of matrix metalloproteinases

A cell's "redox" (oxidation and reduction) state is determined by the sum of all redox processes yielding reactive oxygen species (ROS), reactive nitrogen species (RNS), and other reactive intermediates. Low amounts of ROS/RNS are generated by different mechanisms in every cell and are important regulatory mediators in many signaling processes (redox signaling). When the physiological balance between the generation and elimination of ROS/RNS is disrupted, oxidative/nitrosative stress with persistent oxidative damage of the organism occurs. Oxidative stress has been suggested to act as initiator and/or mediator of many human diseases. The cerebral vasculature is particularly susceptible to oxidative stress, which is critical since cerebral endothelial cells play a major role in the creation and maintenance of the blood-brain barrier (BBB). This article will only contain a focused introduction on the biochemical background of redox signaling, since this has been reported already in a series of excellent recent reviews. The goal of this work is to increase the understanding of basic mechanisms underlying ROS/RNS-induced BBB disruption, with a focus on the role of matrix metalloproteinases, which, after all, appear to be a key mediator in the initiation and progression of BBB damage elicited by oxidative stress.

Hydrogen sulfide protects against chemical hypoxia-induced cytotoxicity and inflammation in HaCaT cells through inhibition of ROS/NF-κB/COX-2 pathway

Hydrogen sulfide (H₂S) has been shown to protect against oxidative stress injury and inflammation in various hypoxia-induced insult models. However, it remains unknown whether H₂S protects human skin keratinocytes (HaCaT cells) against chemical hypoxia-induced damage. In the current study, HaCaT cells were treated with cobalt chloride (CoCl₂), a well known hypoxia mimetic agent, to establish a chemical hypoxia-induced cell injury model. Our findings showed that pretreatment of HaCaT cells with NaHS (a donor of H₂S) for 30 min before exposure to CoCl₂ for 24 h significantly attenuated CoCl₂-induced injuries and inflammatory responses, evidenced by increases in cell viability and GSH level and decreases in ROS generation and secretions of IL-1β, IL-6 and IL-8. In addition, pretreatment with NaHS markedly reduced CoCl₂-induced COX-2 overexpression and PGE₂ secretion as well as intranuclear NF-κB p65 subunit accumulation (the central step of NF-κB activation). Similar to the protective effect of H₂S, both NS-398 (a selective COX-2 inhibitor) and PDTC (a selective NF-κB inhibitor) depressed not only CoCl₂-induced cytotoxicity, but also the secretions of IL-1β, IL-6 and IL-8. Importantly, PDTC obviously attenuated overexpression of COX-2 induced by CoCl₂. Notably, NAC, a ROS scavenger, conferred a similar protective effect of H₂S against CoCl₂-induced insults and inflammatory responses. Taken together, the findings of the present study have demonstrated for the first time that H₂S protects HaCaT cells against CoCl₂-induced injuries and inflammatory responses through inhibition of ROS-activated NF-κB/COX-2 pathway.

Oxidative stress mediates chemical hypoxia-induced injury and inflammation by activating NF-κb-COX-2 pathway in HaCaT cells

Hypoxia of skin is an important physiopathological process in many diseases, such as pressure ulcer, diabetic ulcer, and varicose ulcer. Although cellular injury and inflammation have been involved in hypoxia-induced dermatic injury, the underlying mechanisms remain largely unknown. This study was conducted to investigate the effects of cobalt chloride (CoCl(2)), a hypoxia-mimicking agent, on human skin keratinocytes (HaCaT cells) and to explore the possible molecular mechanisms. Exposure of HaCaT cells to CoCl(2) reduced cell viability and caused overproduction of reactive oxygen species (ROS) and oversecretion of interleukin-6 (IL-6) and interleukin-8 (IL-8). Importantly, CoCl(2) exposure elicited overexpression of cyclooxygenase-2 (COX-2) and phosphorylation of nuclear factor-kappa B (NF-κB) p65 subunit. Inhibition of COX-2 by NS-398, a selective inhibitor of COX-2, significantly repressed the cytotoxicity, as well as secretion of IL-6 and IL-8 induced by CoCl(2). Inhibition of NF-κB by PDTC (a selective inhibitor of NF-κB) or genetic silencing of p65 by RNAi (Si-p65), attenuated not only the cytotoxicity and secretion of IL-6 and IL-8, but also overexpression of COX-2 in CoCl(2)-treated HaCaT cells. Neutralizing anti-IL-6 or anti-IL-8 antibody statistically alleviated CoCl(2)-induced cytotoxicity in HaCaT cells. N-acetyl-L-cysteine (NAC), a well characterized ROS scavenger, obviously suppressed CoCl(2)-induced cytotoxicity in HaCaT cells, as well as secretion of IL-6 and IL-8. Additionally, NAC also repressed overexpression of COX-2 and phosphorylation of NF- B κ p65 subunit induced by CoCl(2) in HaCaT cells. In conclusion, our results demonstrated that oxidative stress mediates chemical hypoxia-induced injury and inflammatory response through activation of NF-κB-COX-2 pathway in HaCaT cells.

Vascular Dysfunction in Brain Hemorrhage: Translational Pathways to Developing New Treatments from Old Targets

Hemorrhagic stroke which is a form of stroke that affects 20% of all stroke patients is a devastating condition for which new treatments must be developed. Current treatment methods are quite insufficient to reduce long term morbidity and high mortality rate, up to 50%, associated with bleeding into critical brain structures, into ventricular spaces and within the subarachnoid space. During the last 10-15 years, significant advances in the understanding of important mechanisms that contribute to cell death and clinical deficits have been made. The most important observations revolve around a key set of basic mechanisms that are altered in brain bleeding models, including activation of membrane metalloproteinases, oxidative stress and both inflammatory and coagulation pathways. Moreover, it is now becoming apparent that brain hemorrhage can activate the ischemic stroke cascade in neurons, glial cells and the vascular compartment. The activation of multiple pathways allows comes the opportunity to intervene pharmacologically using monotherapy or combination therapy. Ultimately, combination therapy or pleiotropic compounds with multi-target activities should prove to be more efficacious than any single therapy alone. This article provides a comprehensive look at possible targets for small molecule intervention as well as some new approaches that result in metabolic down-regulation or inhibition of multiple pathways simultaneously.

Variation of NDRG2 and c-Myc expression in rat heart during the acute stage of ischemia/reperfusion injury

N-Myc downstream regulated gene 2 (NDRG2), a Myc-repressed gene, is highly expressed in heart tissue. NDRG2 increases in response to hypoxia-induced stress and is involved in hypoxia-induced radioresistance. However, little is known about the expression changes and possible roles of NDRG2 in the heart under hypoxia condition. Here, the authors show that NDRG2, mainly localized in cardiomyocyte cytoplasm, was significantly reduced in myocardial tissue after acute ischemia/reperfusion (I/R) injury. Meanwhile, c-Myc was up-regulated following acute I/R injury, and the expression of c-Myc was significantly inversely correlated with that of NDRG2. In addition, overexpression of c-Myc in primary cultured cardiomyocyte repressed NDRG2 expression. Furthermore, the increase of cardiomyocyte apoptosis was correlated with the decrease of NDRG2 protein during the acute phase of reperfusion. These data suggested for the first time that I/R injury-induced up-regulation of pro-apoptotic c-Myc expression may contribute to the down-regulation of anti-apoptotic NDRG2. This stress response might be involved in the novel mechanism of myocardial apoptosis induced by I/R injury in rat.

Uric acid levels are relevant in patients with stroke treated with thrombolysis

BACKGROUND AND PURPOSE

Uric acid (UA) is a neuroprotective antioxidant that improves the benefits of alteplase in experimental ischemia. However, it is unknown whether endogenous UA also influences the response to thrombolysis in patients with stroke.

METHODS

A total of 317 consecutive patients treated with thrombolysis were included in a prospective stroke registry. Demographics, laboratory data, neurological course, and infarction volume were prospectively collected. Excellent outcome was defined as achieving a modified Rankin Scale score <2 at 90 days. Binary and ordinal logistic regression models were used to analyze modified Rankin Scale score at 90 days.

RESULTS

UA levels were significantly higher in patients with an excellent outcome than in patients with a poor outcome (5.82 [1.39] versus 5.42 [1.81], P=0.029). In multivariate models, increased UA levels (OR, 1.23; 95% CI, 1.03 to 1.49; P=0.025) were associated with an excellent outcome and with an increased risk of shifting to a better category across the modified Rankin Scale (OR, 1.19; 95% CI, 1.04 to 1.38; P=0.014) independently of the effect of confounders. The levels of UA and the volume of final infarction were inversely correlated (r=-0.216, P<0.001) and the inverse correlation remained after adjustment for age, sex, and baseline National Institutes of Health Stroke Scale score (t value=-2.54, P=0.01). Significantly lower UA levels were found in patients with malignant middle cerebral artery infarction and parenchymal hemorrhage post-thrombolysis.

CONCLUSIONS

Increased UA serum levels are associated with better outcome in patients with stroke treated with reperfusion therapies. These results support the assessment of the potential neuroprotective role of the exogenous administration of UA in patients with stroke treated with thrombolysis.

Hemoglobin-induced oxidative stress contributes to matrix metalloproteinase activation and blood-brain barrier dysfunction in vivo

Hemoglobin (Hb) released from extravasated erythrocytes is implicated in brain edema after intracerebral hemorrhage (ICH). Hemoglobin is a major component of blood and a potent mediator of oxidative stress after ICH. Oxidative stress and matrix metalloproteinases (MMPs) are associated with blood-brain barrier (BBB) dysfunction. This study was designed to elucidate whether Hb-induced oxidative stress contributes to MMP-9 activation and BBB dysfunction in vivo. An intracerebral injection of Hb into rat striata induced increased hydroethidine (HEt) signals in parallel with MMP-9 levels. In situ gelatinolytic activity colocalized with oxidized HEt signals in vessel walls, accompanied by immunoglobulin G leakage and a decrease in immunoactivity of endothelial barrier antigen, a marker of endothelial integrity. Administration of a nonselective MMP inhibitor prevented MMP-9 levels and albumin leakage in injured striata. Moreover, reduction in oxidative stress by copper/zinc-superoxide dismutase (SOD1) overexpression reduced oxidative stress, MMP-9 levels, albumin leakage, and subsequent apoptosis compared with wild-type littermates. We speculate that Hb-induced oxidative stress may contribute to early BBB dysfunction and subsequent apoptosis, partly through MMP activation, and that SOD1 overexpression may reduce Hb-induced oxidative stress, BBB dysfunction, and apoptotic cell death.