MicroRNA-22 inhibition prevents doxorubicin-induced cardiotoxicity via upregulating SIRT1

Oxidative stress and cardiomyocyte apoptosis contributed to the progression of doxorubicin (Dox)-induced cardiotoxicity. Recent studies identified microRNA-22 (miR-22) as a cardiac- and skeletal muscle-enriched microRNA that functioned as a key regulator in stress-induced cardiac injury. The present study aimed to investigate the role and possible mechanism of miR-22 on Dox-induced oxidative stress and cardiomyocyte apoptosis. Mice were exposed to reduplicative injections of Dox (i.p., 4 mg/kg) weekly for consecutive 4 weeks to generate Dox-induced cardiotoxicity. Herein, we found that miR-22 level was significantly increased in murine hearts subjected to chronic Dox treatment. MiR-22 inhibition attenuated oxidative stress and cardiomyocyte apoptosis in vivo and in vitro, thereby preventing Dox-induced cardiac dysfunction. Mechanistically, we observed that miR-22 directly bound to the 3′-UTR of Sirt1 and caused SIRT1 downregulation. Conversely, miR-22 antagomir upregulated SIRT1 expression and SIRT1 inhibitor abolished the beneficial effects of miR-22 antagomir. In conclusion, miR-22 inhibition prevented oxidative stress and cardiomyocyte apoptosis via upregulating SIRT1 and miR-22 might be a new target for treating Dox-induced cardiotoxicity.     

Quercetin protected against isoniazide‐induced HepG2 cell apoptosis by activating the SIRT1/ERK pathway

Isoniazid (INH) is one of the most commonly used antituberculosis drugs, but its clinical applications have been limited by severe hepatic toxicity. Quercetin (Que), a natural flavonoid, has been proved to have many medicinal properties. This study aimed to clarify the possible protective effects of Que against INH‐induced hepatotoxicity using HepG2 cells. Our results indicated that Que significantly increased cell viability, superoxide dismutase, and GSH levels, while decreased alanine aminotransferase/aspartate aminotransferase levels. Besides, Que significantly abrogated INH‐induced cell apoptosis by upregulating the expression levels of Bcl‐2 and decreasing the levels of Bax, cleaved caspase‐3, and cleaved caspase‐9. Furthermore, Que obviously reversed the inhibition of INH on Sirtuin 1 (SIRT1) expression and extracellular signal‐regulated kinase (ERK) phosphorylation. Next, the SIRT1 inhibitor EX527 blocked the enhancement of Que upon ERK phosphorylation. Notably, EX527 partially abolished the beneficial effects of Que. In brief, our results provided the first evidence that Que protected against INH‐induced HepG2 cells by regulating the SIRT1/ERK pathway.     

Quercetin prevents osteoarthritis progression possibly via regulation of local and systemic inflammatory cascades

Due to the lack of effective treatments, osteoarthritis (OA) remains a challenge for clinicians. Quercetin, a bioflavonoid, has shown potent anti-inflammatory effects. However, its effect on preventing OA progression and the underlying mechanisms are still unclear. In this study, Sprague–Dawley male rats were divided into five groups: control group, OA group (monosodium iodoacetate intra-articular injection), and three quercetin-treated groups. Quercetin-treated groups were treated with intragastric quercetin once a day for 28 days. Gross observation and histopathological analysis showed cartilage degradation and matrix loss in the OA group. High-dose quercetin-group joints showed failure in OA progression. High-dose quercetin inhibited the OA-induced expression of MMP-3, MMP-13, ADAMTS4, and ADAMTS5 and promoted the OA-reduced expression of aggrecan and collagen II. Levels of most inflammatory cytokines and growth factors tested in synovial fluid and serum were upregulated in the OA group and these increases were reversed by high-dose quercetin. Similarly, subchondral trabecular bone was degraded in the OA group and this effect was reversed in the high-dose quercetin group. Our findings indicate that quercetin has a protective effect against OA development and progression possibly via maintaining the inflammatory cascade homeostasis. Therefore, quercetin could be a potential therapeutic agent to prevent OA progression in risk groups.     

Quercetin protects against diabetic encephalopathy via SIRT1/NLRP3 pathway in db/db mice

Epidemiological studies have found that diabetes and cognitive dysfunction are closely related. Quercetin has been certified with the effect on improving diabetes mellitus (DM) and cognitive impairment. However, the effect and related mechanism of quercetin on diabetic encephalopathy (DE) are still ambiguous. In this study, we used the db/db mice (diabetic model) to discover whether quercetin could improve DE through the Sirtuin1/NLRP3 (NOD-, LRR- and pyrin domain-containing 3) pathway. Behavioural results (Morris water maze and new object recognition tests) showed that quercetin (70 mg/kg) improved the learning and memory. Furthermore, quercetin alleviated insulin resistance and the level of fasting blood glucose. Besides, Western blot analysis also showed that quercetin increased the protein expressions of nerve- and synapse-related protein, including postsynapticdensity 93 (PSD93), postsynapticdensity 95 (PSD95), brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the brain of db/db mice. Quercetin also increased the protein expression of SIRT1 and decreased the expression of NLRP3 inflammation-related proteins, including NLRP3, the adaptor protein ASC and cleaved Caspase-1, the pro-inflammatory cytokines IL-1β and IL-18. In conclusion, the present results indicate that the SIRT1/NLRP3 pathway may be a crucial mechanism for the neuroprotective effect of quercetin against DE.     

Cab45S inhibits the ER stress-induced IRE1-JNK pathway and apoptosis via GRP78/BiP

Disturbance of endoplasmic reticulum (ER) homeostasis causes ER stress and leads to activation of the unfolded protein response, which reduces the stress and promotes cell survival at the early stage of stress, or triggers cell death and apoptosis when homeostasis is not restored under prolonged ER stress. Here, we report that Cab45S, a member of the CREC family, inhibits ER stress-induced apoptosis. Depletion of Cab45S increases inositol-requiring kinase 1 (IRE1) activity, thus producing more spliced forms of X-box-binding protein 1 mRNA at the early stage of stress and leads to phosphorylation of c-Jun N-terminal kinase, which finally induces apoptosis. Furthermore, we find that Cab45S specifically interacts with 78-kDa glucose-regulated protein/immunoglobulin heavy chain binding protein (GRP78/BiP) on its nucleotide-binding domain. Cab45S enhances GRP78/BiP protein level and stabilizes the interaction of GRP78/BiP with IRE1 to inhibit ER stress-induced IRE1 activation and apoptosis. Together, Cab45S, a novel regulator of GRP78/BiP, suppresses ER stress-induced IRE1 activation and apoptosis by binding to and elevating GRP78/BiP, and has a role in the inhibition of ER stress-induced apoptosis.     

Decreased vitamin B12 availability induces ER stress through impaired SIRT1-deacetylation of HSF1

Vitamin B12 (cobalamin) is a key determinant of S-adenosyl methionine (SAM)-dependent epigenomic cellular regulations related to methylation/acetylation and its deficiency produces neurodegenerative disorders by elusive mechanisms. Sirtuin 1 deacetylase (SIRT1) triggers cell response to nutritional stress through endoplasmic reticulum (ER) stress. Recently, we have established a N1E115 dopaminergic cell model by stable expression of a transcobalamin–oleosin chimera (TO), which impairs cellular availability of vitamin B12, decreases methionine synthase activity and SAM level, and reduces cell proliferation. In contrast, oleosin-transcobalamin chimera (OT) does not modify the phenotype of transfected cells. Presently, the impaired cellular availability of vitamin B12 in TO cells activated irreversible ER stress pathways, with increased P-eIF-2α, P-PERK, P-IRE1α, ATF6, ATF4, decreased chaperon proteins and increased pro-apoptotic markers, CHOP and cleaved caspase 3, through reduced SIRT1 expression and consequently greater acetylation of heat-shock factor protein 1 (HSF1). Adding either B12, SIRT1, or HSF1 activators as well as overexpressing SIRT1 or HSF1 dramatically reduced the activation of ER stress pathways in TO cells. Conversely, impairing SIRT1 and HSF1 by siRNA, expressing a dominant negative form of HSF1, or adding a SIRT1 inhibitor led to B12-dependent ER stress in OT cells. Addition of B12 abolished the activation of stress transducers and apoptosis, and increased the expression of protein chaperons in OT cells subjected to thapsigargin, a strong ER stress stimulator. AdoX, an inhibitor of methyltransferase activities, produced similar effects than decreased B12 availability on SIRT1 and ER stress by a mechanism related to increased expression of hypermethylated in cancer 1 (HIC1). Taken together, these data show that cellular vitamin B12 has a strong modulating influence on ER stress in N1E115 dopaminergic cells. The impaired cellular availability in vitamin B12 induces irreversible ER stress by greater acetylation of HSF1 through decreased SIRT1 expression, whereas adding vitamin B12 produces protective effects in cells subjected to ER stress stimulation.     

Resveratrol improves oxidative stress and prevents the progression of periodontitis via the activation of the Sirt1/AMPK and the Nrf2/antioxidant defense pathways in a rat periodontitis model

Oxidative stress is a key factor regulating the systemic pathophysiological effects associated with periodontitis. Resveratrol is a phytochemical with antioxidant and anti-inflammatory properties that can reduce oxidative stress and inflammation. We hypothesized that resveratrol may prevent the progression of periodontitis and reduce systemic oxidative stress through the activation of the sirtuin 1 (Sirt1)/AMP-activated protein kinase (AMPK) and the nuclear factor E2-related factor 2 (Nrf2)/antioxidant defense pathways. Three groups of male Wistar rats (periodontitis treated with melinjo resveratrol, periodontitis without resveratrol, and control rats with no periodontitis or resveratrol treatment) were examined. A ligature was placed around the maxillary molars for 3 weeks to induce periodontitis, and the rats were then given drinking water with or without melinjo resveratrol. In rats with periodontitis, ligature placement induced alveolar bone resorption, quantified using three-dimensional images taken by micro-CT, and increased proinflammatory cytokine levels in gingival tissue. Melinjo resveratrol intake relieved alveolar bone resorption and activated the Sirt1/AMPK and the Nrf2/antioxidant defense pathways in inflamed gingival tissues. Further, melinjo resveratrol improved the systemic levels of 8-hydroxydeoxyguanosine, dityrosine, nitric oxide metabolism, nitrotyrosine, and proinflammatory cytokines. We conclude that oral administration of melinjo resveratrol may prevent the progression of ligature-induced periodontitis and improve systemic oxidative and nitrosative stress.     

The TSC1 and TSC2 tumor suppressors are required for proper ER stress response and protect cells from ER stress-induced apoptosis

Tuberous sclerosis complex (TSC)1 and TSC2 are tumor suppressors that inhibit cell growth and mutation of either gene causes benign tumors in multiple tissues. The TSC1 and TSC2 gene products form a functional complex that has GTPase-activating protein (GAP) activity toward Ras homolog enriched in brain (Rheb) to inhibit mammalian target of rapamycin complex 1 (mTORC1), which is constitutively activated in TSC mutant tumors. We found that cells with mutation in either TSC1 or TSC2 are hypersensitive to endoplasmic reticulum (ER) stress and undergo apoptosis. Although the TSC mutant cells show elevated eIF2α phosphorylation, an early ER stress response marker, at both basal and induced conditions, induction of other ER stress response markers, including ATF4, ATF6 and C/EBP homologous protein (CHOP), is severely compromised. The defects in ER stress response are restored by raptor knockdown but not by rapamycin treatment in the TSC mutant cells, indicating that a rapamycin-insensitive mTORC function is responsible for the defects in ER stress response. Consistently, activation of Rheb sensitizes cells to ER stress. Our data show an important role of TSC1/TSC2 and Rheb in unfolded protein response and cell survival. We speculate that an important physiological function of the TSC1/2 tumor suppressors is to protect cells from harmful conditions. These observations indicate a potential therapeutic application of using ER stress agents to selectively kill TSC1 or TSC2 mutant cells for TSC treatment.     

Fumonisin B1 actuates oxidative stress‐associated colonic damage via apoptosis and autophagy activation in murine model

In the present study, we investigated the cytotoxic mechanism of Fumonisin B1 (FB1) in mice colonic region in a time course manner. Herein, after consecutive 4 days of exposure to FBI (2.5 mg/kg body weight), we observed disintegration of mice colon, as evidenced by histopathological analysis. FB1 significantly increased alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase activities in serum and plasma, decreased ceramide level, increased sphinganine level, and increased lipid peroxidase level along with the breakdown of the antioxidant system. Further, FB1‐induced ER stress caused apoptosis and autophagy activation in mice colon, evidenced by increased expression of IRE1‐α, p‐JNK, Casp3, and LC3I/II. In addition, we also noticed a reduced protein kinase C expression in mice colon exposed to FB1, suggesting its role in ER stress‐induced cell death. Taken together, study suggests both physiologically and biochemically, FB1 toxicity to mice colon induced by oxidative stress‐associated apoptosis and autophagy activation.     

Protective effect of quercetin on lead-induced oxidative stress and endoplasmic reticulum stress in rat liver via the IRE1/JNK and PI3K/Akt pathway

Abstract

Lead (Pb), a well-known environmental toxin, is one of the major hazards for human health. Quercetin (QE), a natural flavonoid, has been reported to have many benefits and medicinal properties. However, its protective effects against Pb-induced endoplasmic reticulum (ER) stress in liver have not been clarified. The aim of the present study was to investigate the effects of quercetin on hepatic ER stress in rats exposed to Pb. Wistar rats were exposed to lead acetate in the drinking water with or without quercetin co-administration for 75 days. Our data showed that quercetin significantly prevented Pb-induced hepatotoxicity in a dose-dependent manner, indicated by both diagnostic indicators of liver damage and histopathological analysis. Quercetin markedly decreased Pb contents in blood and liver. Western blot analysis showed that Pb-induced ER stress in rat liver was significantly inhibited by quercetin. In exploring the underlying mechanisms of quercetin action, we found quercetin markedly suppressed Pb-induced oxidative stress. Quercetin decreased reactive oxygen species (ROS) production and increased the total antioxidant capacity in rat livers. Additionally, quercetin dramatically increased Phosphoinositide-3-kinase (PI3K) and phosphorylated protein kinase B (PKB/Akt) levels in liver rats. In the examined unfolded protein response (UPR) pathways, quercetin markedly inhibited the Pb-induced increase of the phosphorylated inositol-requiring enzyme 1 (IRE1) and c-jun N-terminal kinase (JNK) in rat liver. Taken together, these results suggested that the inhibition of Pb-induced ER stress by quercetin is due at least in part to its anti-oxidant stress activity and its ability to modulate the PI3K/Akt and IRE1/JNK signaling pathway.     

Theaflavin protects against oxalate calcium-induced kidney oxidative stress injury via upregulation of SIRT1

Renal tubular cell injury induced by calcium oxalate (CaOx) is a critical initial stage of kidney stone formation. Theaflavin (TF) has been known for its strong antioxidative capacity; however, the effect and molecular mechanism of TF against oxidative stress and injury caused by CaOx crystal exposure in kidneys remains unknown. To explore the potential function of TF on renal crystal deposition and its underlying mechanisms, experiments were conducted using a CaOx nephrocalcinosis mouse model established by glyoxylate intraperitoneal injection, and HK-2 cells were subjected to calcium oxalate monohydrate (COM) crystals, with or without the treatment of TF. We discovered that TF treatment remarkably protected against CaOx-induced kidney oxidative stress injury and reduced crystal deposition. Additionally, miR-128-3p expression was decreased and negatively correlated with SIRT1 level in mouse CaOx nephrocalcinosis model following TF treatment. Moreover, TF suppressed miR-128-3p expression and further abolished its inhibition on SIRT1 to attenuate oxidative stress in vitro. Mechanistically, TF interacted with miR-128-3p and suppressed its expression. In addition, miR-128-3p inhibited SIRT1 expression by directly binding its 3''-untranslated region (UTR). Furthermore, miR-128-3p activation partially reversed the acceerative effect of TF on SIRT1 expression. Taken together, TF exhibits a strong nephroprotective ability to suppress CaOx-induced kidney damage through the recovery of the antioxidant defense system regulated by miR-128-3p/SIRT1 axis. These findings provide novel insights for the prevention and treatment of renal calculus.     

Quercetin treatment against ischemia/reperfusion injury in rat corpus cavernosum tissue: a role on apoptosis and oxidative stress

Abstract

Reactive oxygen metabolites play an important role in the ischemia/reperfusion (I/R)-induced tissue injury. This study was designed to investigate the possible protective effects of quercetin against I/R injury of the rat corpus cavernosum tissue. To induce I/R injury, abdominal aorta was clamped for 30 min and reperfused for 60 min. Quercetin (20 mg/kg) or vehicle was given before ischemia and just after reperfusion in the I/R group and in the sham-operated control group in which clamping was not performed. After decapitation, corpus cavernosum tissues were removed and either placed in organ baths or stored for evaluating biochemical parameters. Oxidative injury was examined by measuring lucigenin chemiluminescence (CL), nitric oxide (NO), malondialdehyde (MDA) and glutathione (GSH) levels, superoxide dismutase (SOD) and myeloperoxidase (MPO) activities and caspase-3 protein levels. In the I/R group, contractile responses to phenylephrine and relaxation responses to carbachol were impaired significantly compared with those in the control groups, while quercetin treatment in I/R group reversed both of the responses. On the other hand, increase in lucigenin CL, NO, MDA levels and MPO and caspase-3 activities and decrease in GSH levels and SOD activity in the cavernosal tissues of the I/R group were also significantly reversed by quercetin treatment. Furthermore, observed distorted morphology with ruptured endothelial cells and vacuolization in the cytoplasm of cavernosal tissues of I/R no longer persisted in the quercetin-treated I/R group. Thus, our results suggested that treatment with quercetin may have some benefits in controlling I/R-induced tissue injury through its anti-inflammatory, anti-apoptotic, and antioxidant effects.     

Elabela may regulate SIRT3-mediated inhibition of oxidative stress through Foxo3a deacetylation preventing diabetic-induced myocardial injury

Diabetic cardiomyopathy—pathophysiological heart remodelling and dysfunction that occurs in absence of coronary artery disease, hypertension and/or valvular heart disease—is a common diabetic complication. Elabela, a new peptide that acts via Apelin receptor, has similar functions as Apelin, providing beneficial effects on body fluid homeostasis, cardiovascular health and renal insufficiency, as well as potentially beneficial effects on metabolism and diabetes. In this study, Elabela treatment was found to have profound protective effects against diabetes-induced cardiac oxidative stress, inflammation, fibrosis and apoptosis; these protective effects may depend heavily upon SIRT3-mediated Foxo3a deacetylation. Our findings provide evidence that Elabela has cardioprotective effects for the first time in the diabetic model.     

Targeted regulation of FoxO1 in chondrocytes prevents age‐related osteoarthritis via autophagy mechanism

Autophagy is designated as a biological recycling process to maintain cellular homeostasis by the sequestration of damaged proteins and organelles in plasma and cargo delivery to lysosomes for degradation and reclamation. This organelle recycling process promotes chondrocyte homeostasis and has been previously implicated in osteoarthritis (OA). Autophagy is widely involved in regulating chondrocyte degeneration markers such as MMPs, ADAMSTs and Col10 in chondrocytes. The critical autophagy‐related (ATG) proteins have now been considered the protective factor against late‐onset OA. The current research field proposes that the autophagic pathway is closely related to chondrocyte activity. However, the mechanism is complex yet needs precise elaboration. This review concluded that FoxO1, a forkhead O family protein, which is a decisive mediator of autophagy, facilitates the pathological process of osteoarthritis. Diverse mechanisms regulate the activity of FoxO1 and promote the initiation of autophagy, including the prominent AMPK and Sirt‐2 cellular pathways. FoxO1 transactive is regulated by phosphorylation and acetylation processes, which modulates the downstream ATGs expression. Furthermore, FoxO1 induces autophagy by directly interacting with ATGs proteins, which control the formation of autophagosomes and lysosomes fusion. This review will discuss cutting‐edge evidence that the FoxO–autophagy pathway plays an essential regulator in the pathogenesis of osteoarthritis.     

Pravastatin attenuates carboplatin-induced cardiotoxicity via inhibition of oxidative stress associated apoptosis

The objective of this study was to evaluate the cardiac toxicity induced by carboplatin, a second generation platinum-containing anti-cancer drug, and to test whether pravastatin can reduce this cardio-toxicity. In the present study, infusion of carboplatin (100 mg/kg) to mice resulted in decreased survival rates and abnormal cardiac histology, concomitant with increased cardiac apoptosis. In addition, treatment of cultured rat cardiomyocytes with carboplatin (100 μM for 48 h) caused marked apoptosis and increased caspase-3, -9, and cytochrome C, but decreased BCL-XL protein expression, and this was inhibited by reactive oxygen species (ROS) scavenger n-acetylcysteine. Furthermore, pretreatment of cardiomyocytes with pravastatin (20 μM) before carboplatin exposure significantly attenuated apoptosis and decreased caspase-3, -9, cytochrome C activity. Lastly, mice pre-treated with pravastatin before carboplatin treatment showed improved survival rate and cardiac function, with reduced cardiomyocyte apoptosis via activating Akt and restoring normal mitochondrial HAX-1 in heart tissue. In summary, our results show that carboplatin can induce cardiotoxicity in vivo and in cultured cells via a mitochondrial pathway related to ROS production, whereas pravastatin administration can reduce such oxidative stress thus prevented cardiac apoptosis. Therefore, pravastatin can be used as a cytoprotective agent prior to carboplatin chemotherapy. Ching-Feng Cheng and Shu-Hui Juan contributed equally to the work.     

SIRT1 is upregulated in cutaneous T-cell lymphoma,and its inhibition induces growth arrest and apoptosis

Silent information regulator type-1 (SIRT1) is the best-studied member of the Sirtuin (Sir2) family of nicotinamide dinucleotide (NAD)-dependent class III histone deacetylases (HDACs), but has not yet been explored in cutaneous T-cell lymphoma (CTCL). We analyzed five CTCL cell lines and lesional tissues using flow cytometry, immunostaining, immunoblotting, cell death, viability, and apoptosis assays, small-molecule inhibitors, and shRNA knockdown. We found strong SIRT1 expression among CTCL lines relative to normal lymphocytes. CTCL cells in lesional tissues also expressed SIRT1 strongly. SIRT1 knockdown resulted in reduced cellular metabolism and proliferation, increased apoptosis, and PARP cleavage products. Tenovin-1, which reversibly inhibits class III HDACs (SIRT1 and SIRT2), reduced SIRT enzymatic activity and SIRT1 expression and led to increased apoptosis. These alterations were accompanied by increased forkhead box O3 (FoxO3) in several cell lines and increased nuclear p53, as well as acetylated p53 in wtp53 MyLa CTCL line. A combination of class I/II and class III HDACIs (vorinostat and tenovin-1) produced significantly greater growth inhibition, cell death via apoptosis, as well as superior p53 promoter upregulation in wtp53 MyLa cells as compared with either agent alone. This occurred in a partially p53-dependent manner, as these effects were blunted by p53 knockdown. Our results indicate that SIRT1 is strongly expressed in CTCL. Its inhibition results in reduced growth and increased apoptosis of CTCL cells. Furthermore, our findings suggest that some CTCL patients, such as those with wtp53, might benefit more from treatment with a combination of different classes of HDACIs than with a single agent.     

PDK1 promotes apoptosis of chondrocytes via modulating MAPK pathway in osteoarthritis

3-Phosphoinositide dependent protein kinase-1 (PDK1), a serine threonine kinase, belongs to the AGC kinase family and is associated with apoptosis. The aim of this study was to investigate the expression of PDK1 (3-Phosphoinositide dependent protein kinase-1) in articular cartilage with osteoarthritis (OA) and to analyze the relationship between PDK1 and chondrocyte apoptosis. Immunohistochemistry and RT-PCR analysis showed that the expression of PDK1 in articular cartilage of OA patients and healthy controls. IL-1β-stimulated SW1353 cells were used to imitate the OA-like chondrocyte injury in vitro, and IL-1β-induced the expression of PDK1, apoptotic markers(PARP, caspase-3), and phosphorylated p38 were detected by Western blot. The co-localization of PDK1 and Cleaved-caspase3 was confirmed through immunofluorescence. Knocking down PDK1 expression through PDK1 siRNA. Western blot was performed to detect the knockdown efficiency of PDK1 and the impact of PDK1 knockout on IL-1β-induced expression of apoptotic markers and phosphorylated p38 in SW1353 cells. Flow Cytometry-Based Annexin V/PI Staining was used to exam chondrocyte apoptosis. Our experimental results suggested that PDK1 may promote chondrocyte apoptosis in OA via p38 MAPK signaling pathway.     

Thioredoxin-1 attenuates post-ischemic neuronal apoptosis via reducing oxidative/nitrative stress

Recent studies show that Thioredoxin (Trx) possesses a neuronal protective effect and that Trx inactivation is closely related to cerebral ischemia injury. Peroxynitrite (ONOO⁻) formation may trigger oxidative/nitrative stress and represent a major cytotoxic effect in cerebral ischemia. The present study was conducted to validate whether treatment with recombinant human Trx-1 (rhTrx-1) would attenuate ONOO⁻ generation and oxidative/nitrative stress in focal transient cerebral ischemia. The results showed that intravenously administered rhTrx-1 (10 mg/kg) significantly improved neurological functions and reduced cerebral infarction and apoptotic cell death following cerebral ischemia. Neuronal ONOO⁻ formation was significantly attenuated after rhTrx-1 treatment. Moreover, rhTrx-1 resulted in a significant decrease in antioxidant capacity and p38 mitogen activated protein kinase (MAPK) activity in ischemic brain tissue. Furthermore, the suppression on ONOO⁻ formation by either rhTrx-1 or an ONOO⁻ scavenger uric acid reduced cerebral infarct size in mice subjected to cerebral ischemia. Peroxynitrite donor SIN-1 not only blocked the neuronal protection of rhTrx-1 but also markedly attenuated rhTrx-1-induced antioxidative/antinitrative effect. We concluded that rhTrx-1 exerts an antioxidative/antinitrative effect against cerebral ischemia injury by blocking ONOO⁻ and superoxide anion formation. These results provide the information that thioredoxin is much more likely to succeed as a therapeutic approach to diminish oxidative/nitrative stress-induced neuronal apoptotic cell death in the ischemic brain.