Nrf2 in bone marrow-derived cells positively contributes to the advanced stage of atherosclerotic plaque formation

Atherosclerosis is the major etiology underlying myocardial infarction and stroke, and strategies for preventing atherosclerosis are urgently needed. In the context of atherosclerosis, the deletion of the Nrf2 gene, which encodes a master regulator of the oxidative stress response in mammals, reportedly attenuates atherosclerosis formation. However, the precise mechanisms of protection against atherosclerosis are largely unknown. To further clarify the role of Nrf2 in atherosclerosis in vivo, we performed a time course analysis of atherosclerosis development utilizing an ApoE knockout (KO) mouse model. The results demonstrate that oil red O-stainable lesions were similar in size 5 weeks after the initiation of an HFC (high fat and high cholesterol) diet, but the lesions were markedly attenuated in the Nrf2 and ApoE double KO mice (A0N0 mice) compared with the lesions in the ApoE KO mice (A0N2 mice) at 12 weeks. Consistent with these results, the immunohistochemical analysis revealed that Nrf2 activation is observed in late-stage atherosclerotic plaques but not in earlier lesions. The RT-qPCR analysis of 12-week atherosclerotic plaques revealed that Nrf2 target genes, such as Ho-1 and SLPI, are expressed at significantly lower levels in the A0N0 mice compared with the A0N2 mice, and this change was associated with a decreased expression of macrophage M1-subtype genes Arginase II and inducible NO synthase in the A0N0 mice. Furthermore, the bone marrow (BM) transplantation (BMT) analysis revealed that the Nrf2 activity in the BM-derived cells contributed to lesion formation. Therefore, our study has characterized the positive role of Nrf2 in the BM-derived cells during the development of atherosclerosis, which suggests that Nrf2 may influence the inflammatory reactions in the plaques.

Mkp-1 cross-talks with Nrf2/Ho-1 pathway protecting against intestinal inflammation

Inflammatory bowel disease (IBD) is associated with intense oxidative stress, contributes to colonic damage and tumorigenesis. Mitogen-activated protein kinase phosphatase 1 (Mkp-1) is an essential negative regulator of the innate immune response. However, its role in colitis, and its association with the nuclear factor-erythroid 2 related factor 2 (Nrf2), a master regulator of cytoprotection program against oxidative stress, in inflammatory response, is elusive. In this study, we found that increased expression of Mkp-1, Nrf2, and heme oxygenase 1 (Ho-1) was correlated in colonic tissues in patients with ulcerative colitis and Crohn's disease, as well as wild-type mice with colitis induced by dextran sodium sulfate (DSS). Mkp-1^-/- mice were more susceptible to DSS-induced colitis with more severe crypt injury and inflammation. Mechanistically, directly interacting with the DIDLID motif of Nrf2, Mkp-1 increased Nrf2 stability and positively regulated the constitutive and lipopolysaccharide (LPS)-inducible Nrf2/Ho-1 expression. Conversely, upon exposure to LPS, Nrf2 activated Mkp-1 transcription through the antioxidant response elements in the promoter of Mkp-1. Our results revealed a novel link between Mkp-1 and Nrf2 signaling pathways in protecting against colonic inflammation. Mkp-1 might be a therapeutic target for IBD.

MicroRNA-24 inhibits the oxidative stress induced by vascular injury by activating the Nrf2/Ho-1 signaling pathway

BACKGROUND AND AIMS

The process of endothelial repair in diabetic patients after stent implantation was significantly delayed compared with that in non-diabetic patients, and oxidative stress is increasingly considered to be relevant to the pathogenesis of diabetic endothelial repair. However, the mechanisms linking diabetes and reendothelialization after vascular injury have not been fully elucidated. The aim of this study was to evaluate the effect of microRNA-24 (miR-24) up-regulation in delayed endothelial repair caused by oxidative stress after balloon injury in diabetic rats.

METHODS

In vitro, vascular smooth muscle cells (VSMCs) isolated from the thoracic aorta were stimulated with high glucose (HG) after miR-24 recombinant adenovirus (Ad-miR-24-GFP) transfection for 3 days. In vivo, diabetic rats induced using high-fat diet (HFD) and low-dose streptozotocin (30 mg/kg) underwent carotid artery balloon injury followed by Ad-miR-24-GFP transfection for 20 min.

RESULTS

The expression of miR-24 was decreased in HG-stimulated VSMCs and balloon-injured carotid arteries of diabetic rats, which was accompanied by increased expression of Ogt and Keap1 and decreased expression of Nrf2 and Ho-1. Up-regulation of miR-24 suppressed VSMC oxidative stress induced by HG in vitro, and miR-24 up-regulation promoted reendothelialization in balloon-injured diabetic rats. The underlying mechanism was related to the activation of the Nrf2/Ho-1 signaling pathway, which subsequently suppressed intracellular reactive oxidative species (ROS) production and malondialdehyde (MDA) and NADPH oxidase (Nox) activity, and to the restoration of Sod and Gsh-px activation.

CONCLUSIONS

The up-regulation of miR-24 significantly promoted endothelial repair after balloon injury through inhibition of oxidative stress by activating the Nrf2/Ho-1 signaling pathway.

Protective role of zinc oxide nanoparticles in kidney injury induced by cisplatin in rats

Cisplatin used as chemotherapy for various cancers may leads to accumulation of platinum within the kidney and disturb its function. Zinc oxide nanoparticles (ZnO-NPs) are of low toxicity nanomaterials and have many medical fields so this study aims to indicate ZnO-NPs effect in kidney injury induced by cisplatin. Adult male rats were pre-injected with one dose of ZnO-NPs (5 mg/kg IP) and after 2 h from injection, the rats were injected with also only one dose of cisplatin (6 mg/kg IP) and two additional groups were served as controls treated with either ZnO-NPs or cisplatin only, respectively, and normal control was involved and euthanization occurred after 7 and 12 days. Cisplatin-induced nephropathy increased kidney function parameters; serum creatinine, blood urea nitrogen and microalbuminuria. Conversely, these parameters were down regulated after ZnO-NPs treatment. ZnO-NPs reversed the decrease of renal superoxide dismutase, catalase and glutathione reductase and the increase of renal malondialdehyde induced by cisplatin. In addition, the annexin V demonstrated that the proportion of viable cells was significantly elevated and the proportion of apoptotic and necrotic cells significantly reduced. Also, the level of renal transforming growth factor beta 1 decreased in group pre-treated with ZnO-NPs. The Nuclear factor-E2-related factor, heme oxygenase-1 and endothelial nitric oxide synthase expression genes were up regulated while Bcl-2-associated X protein expression was down regulated in kidney tissue via ZnO-NPs. Histopathological and immunohistochemical observations were context with these findings. In conclusion, ZnO-NPs treatment revealed renoprotective effect against cisplatin drug, probably via its antioxidant, anti-inflammatory and antiapoptotic properties.

Butylated hydroxyanisole induces distinct expression patterns of Nrf2 and detoxification enzymes in the liver and small intestine of C57BL/6 mice

Butylated hydroxyanisole (BHA) is widely used as an antioxidant and preservative in food, food packaging and medicines. Its chemopreventive properties are attributing to its ability to activate the transcription factor NF-E2 p45-related factor 2 (Nrf2), which directs central genetic programs of detoxification and protection against oxidative stress. This study was to investigate the histological changes of Nrf2 and its regulated phase II enzymes Nqo1, AKR1B8, and Ho-1 in wild-type (WT) and Nrf2(-/-) mice induced by BHA. The mice were given a 200mg/kg oral dose of BHA daily for three days. Immunohistochemistry revealed that, in the liver from WT mice, BHA increased Nqo1 staining in hepatocytes, predominately in the pericentral region. In contrast, the induction of AKR1B8 appeared mostly in hepatocytes in the periportal region. The basal and inducible Ho-1 was located almost exclusively in Kupffer cells. In the small intestine from WT mice, the inducible expression patterns of Nqo1 and AKR1B8 were nearly identical to that of Nrf2, with more intense staining in the villus than that the crypt. Conversely, Keap1 was more highly expressed in the crypt, where the proliferative cells reside. Our study demonstrates that BHA elicited differential expression patterns of phase II-detoxifying enzymes in the liver and small intestine from WT but not Nrf2(-/-) mice, demonstrating a cell type specific response to BHA in vivo.

Fas receptor-deficient lpr mice are protected against acetaminophen hepatotoxicity due to higher glutathione synthesis and enhanced detoxification of oxidant stress

Acetaminophen (APAP) overdose is a classical model of hepatocellular necrosis; however, the involvement of the Fas receptor in the pathophysiology remains controversial. Fas receptor-deficient (lpr) and C57BL/6 mice were treated with APAP to compare the mechanisms of hepatotoxicity. Lpr mice were partially protected against APAP hepatotoxicity as indicated by reduced plasma ALT and GDH levels and liver necrosis. Hepatic Cyp2e1 protein, adduct formation and hepatic glutathione (GSH) depletion were similar, demonstrating equivalent reactive metabolite generation. There was no difference in cytokine formation or hepatic neutrophil recruitment. Interestingly, hepatic GSH recovered faster in lpr mice than in wild type animals resulting in enhanced detoxification of reactive oxygen species. Driving the increased GSH levels, mRNA induction and protein expression of glutamate-cysteine ligase (gclc) were higher in lpr mice. Inducible nitric oxide synthase (iNOS) mRNA and protein levels at 6h were significantly lower in lpr mice, which correlated with reduced nitrotyrosine staining. Heat shock protein 70 (Hsp70) mRNA levels were substantially higher in lpr mice after APAP.

CONCLUSION

Our data suggest that the faster recovery of hepatic GSH levels during oxidant stress and peroxynitrite formation, reduced iNOS expression and enhanced induction of Hsp70 attenuated the susceptibility to APAP-induced cell death in lpr mice.

Promising toxicological biomarkers for the diagnosis of liver injury types: Bile acid metabolic profiles and oxidative stress marker as screening tools in drug development

Promising biomarkers were identified in adult male Crl:CD (SD) rats for the screening of new chemical entities for their potential to cause liver injury. We examined the serum biochemistry, liver histopathology, and bile acid profiles by LC-MS/MS, and the mRNA expression of transporters and CYPs by an RT-PCR after the following treatments to male Crl:CD (SD) rats: (a) bile duct ligation (BDL); (b) a single oral dose of 150 mg/kg α-naphthylisothiocyanate (ANIT); and (c) repeated oral doses of a novel pyrrolidinecarboxylic acid derivative (abbreviated as PCA) at 30, 300, and 1000 mg/kg. The serum total bile acid levels and bilirubin concentrations were found to be elevated in all of the groups. However, the bile acid component profiles of the PCA group differed significantly from BDL and ANIT models: deoxycholic acid, lithocholic acid, and sulfated bile acids were upregulated in a dose-dependent manner only in the PCA group. In addition, the PCA group demonstrated high levels of hepatic heme oxygenase-1 expression, whereas the profiles of the mRNA levels of the hepatic transporters and CYPs of all groups were found to be similar. The histopathological findings, for both the BDL and ANIT groups, were of bile duct hyperplasia, hepatocyte degeneration and necrosis. In contrast, only bile duct hyperplasia and hepatocyte degeneration were observed in the PCA group, even at a lethal dose. These results indicated that PCA induced a cholestatic condition and the increase of oxidative stress markers implies that this will also lead hepatocellular injury. In conclusion, the serum bile acid components and sulfated bile acid levels, and the expression of oxidative stress markers could provide information that aids in the diagnosis of liver injury type and helps to elucidate the mechanisms of hepatotoxicity. These findings can be extrapolated into our clinical investigation. The analysis of these crucial biomarkers is likely to be a useful screening tool in the lead optimization phase of drug discovery.

Amelioration of high fat diet-induced nephropathy by cilostazol and rosuvastatin

Multiple comorbidities of metabolic disorders are associated with facilitated chronic kidney disease progression. Anti-platelet cilostazol is used for the treatment of peripheral artery disease. In this study, we investigated the potential beneficial effects of cilostazol and rosuvastatin on metabolic disorder-induced renal dysfunctions. C57BL/6 mice that received high fat diet (HFD) for 22 weeks and a low dose of streptozotocin (STZ, 40 mg/kg) developed albuminuria and had increased urinary cystatin C excretion, and cilostazol treatment (13 weeks) improved these markers. Histopathological changes, including glomerular mesangial expansion, tubular vacuolization, apoptosis, and lipid accumulation were ameliorated by cilostazol treatment. Tubulointerstitial fibrosis that was indicated by the increases in collagen and transforming growth factor-β1 subsided by cilostazol. Renoprotective effects were also observed in rosuvastatin-treated mice, and combinatorial treatment with cilostazol and rosuvastatin demonstrated enhanced ameliorative effects in histopathological evaluations. Notably, repressed renal heme oxygenase-1 (Ho-1) level in HFD/STZ mice was restored in cilostazol group. Further, we demonstrated that cilostazol enhanced Nrf2/Ho-1 signaling in cultured proximal tubular epithelial cells. Collectively, these results suggest the potential advantageous use of cilostazol as an adjunctive therapy with statins for the amelioration of metabolic disorder-associated renal injury.

Ontogeny and aging of Nrf2 pathway genes in livers of rats

The Nrf2/Keap1 antioxidant system plays important roles in protecting against oxidative stress and toxic stimuli, which may vary in infants, elderly, and females.

AIM

The constitutive expression of the Nrf2 genes during development and aging in both sexes would help our understanding of the Nrf2/Keap1 pathway in toxicological studies.

MAIN METHODS

Sprague Dawley rat livers were collected at 11 age points from prenatal (-2 d), neonatal (1, 7, 14 and 21 d), at puberty (28 and 35 d), at adulthood (60 and 180 d), to aging (540 and 800 d) from both sexes. Total RNA and proteins were extracted for real-time RT-PCR and Western-blot analysis.

KEY FINDINGS

The abundant mRNA expression was in the order of Nrf2, Gclm, Nqo1, Gclc, Ho-1, and Keap1. The expression of these genes except Gclc was high in fetal livers, decreased at birth, reached the first peak at 7 days of age, and gradually decreased to adult levels till 180 days of age. All these genes remained high at 540 days of age, but declined at 800 days of age, with more increases with Nqo1 and Ho-1. Females had lower fetal, neonatal, and aged levels than males. Protein expressions of Nrf2, Nqo1, Ho-1, GCLC and GCLM agree with mRNA analysis.

SIGNIFICANCE

This study characterized the age- and sex-related changes of Nrf2-related gene/proteins in livers of rats, and higher expressions in newborns and aged rats could cope with increased oxidative stress in infants and elderly.

Modulation of aryl hydrocarbon receptor-regulated enzymes by trimethylarsine oxide in C57BL/6 mice: In vivo and in vitro studies

Arsenic is a worldwide environmental pollutant that is associated with skin and several types of internal cancers. Recent reports revealed that arsenic biomethylation could activate the toxic and carcinogenic potential of arsenic. Therefore, we investigated the effect of trimethylarsine oxide (TMAO) on the activation of AhR-regulated genes in vivo and in vitro. In vivo, C57BL/6 mice received TMAO (13mg/kg i.p.) with or without the prototypical AhR ligand, TCDD (15μg/kg), then the livers were harvested at 6 and 24h post-treatment. In vitro, isolated hepatocytes from C57BL/6 mice were treated with TMAO (5μM) in the absence and presence of TCDD (1nM) for 6 and 24h. Our in vivo results demonstrated that, TMAO alone increased Cyp1a1, Cyp1a2, Cyp1b1, Nqo1, Gsta1, and Ho-1 at mRNA level. Upon co-exposure to TMAO and TCDD, TMAO potentiated the TCDD-mediated induction of Cyp1a1, Cyp1b1, and Nqo1 mRNA levels. Western blotting revealed that, TMAO alone increased Cyp1a1, Cyp1a2, Nqo1, Gsta1/2, and Ho-1 protein levels, and potentiated the TCDD-mediated induction of Cyp1a1 and Cyp1b1 protein level. In addition, TMAO alone significantly increased Cyp1a1, Cyp1a2, Nqo1, Gst, and Ho-1 activities and significantly potentiated the TCDD-mediated induction of Cyp1a1 activity. At the in vitro level, TMAO induced Cyp1a1 and potentiated the TCDD-mediated induction of Cyp1a1 at mRNA, protein and activity levels. In addition, TMAO increased the nuclear localization of AhR and AhR-dependent XRE-driven luciferase activity. Our results demonstrate that the TMAO, modulates AhR-regulated genes which could potentially participate, at least in part, in arsenic induced toxicity and carcinogenicity.

Radical-scavenging and Pro-/anti-inflammatory Activity of Tetracycline and Related Phenolic Compounds With or Without Visible Light Irradiation

BACKGROUND/AIM

Microbial tetracycline (TC) pastes have been employed to treat oral bacterial infection. In the present study, we investigated the kinetic radical-scavenging and pro-/anti-inflammatory activity of TC with or without visible light irradiation (VLI).

MATERIALS AND METHODS

The radical-scavenging activity of TC and minocycline (MC) was determined by differential scanning calorimetry (DSC). The stoichiometric factor (n) and the rate constant of inhibition and propagation (kinh/kp) were determined. The levels of cyclooxygenase-2 (Cox2), tumor necrosis factor-α (Tnfα) or nitric oxide synthase 2 (Nos2) mRNA in RAW264.7 cells stimulated with lipopolysaccharide (LPS) were investigated using real-time reverse transcriptase-polymerase chain reaction.

RESULTS

The n and kinh/kp values for 1 mM TC in 2,2'-azobisisobutyronitrile and benzoyl peroxide systems were 0.1-0.2 and 119-250, respectively, whereas the corresponding values for quercetin (QU) and resveratrol (RE) were 2-4 and 7-15, respectively. In RAW264.7 cells stimulated with LPS, Cox2 and Tnfα mRNA were over-expressed in the presence of TC. MC down-regulated only the expression of Cox2 by about 50% in LPS-stimulated cells. The anti-inflammatory activity determined on the basis of Cox2 inhibition declined in the order QU>RE>MC>TC. Upon application of VLI, only TC down-regulated the expression of LPS-stimulated Cox2 and Tnfα mRNA. After exposure to VLI, TC, but not MC, markedly up-regulated hemoxygenase-1 (Ho-1) expression.

CONCLUSION

TC is a chain-breaking antioxidant with a large kinh Upon activation by VLI, TC may undergo degradation and its degradation products affect pleiotropic mediators such as Cox2, Tnfα and Ho-1. TC may be useful as a local photodynamic therapy for periodontal diseases.

Prominent role of exopeptidase DPP III in estrogen-mediated protection against hyperoxia in vivo

A number of age-related diseases have a low incidence in females, which is attributed to a protective effect of sex hormones. For instance, the female sex hormone estrogen (E₂) has a well established cytoprotective effect against oxidative stress, which strongly contributes to ageing. However, the mechanism by which E₂ exerts its protective activity remains elusive.

In this study we address the question whether the E₂-induced protective effect against hyperoxia is mediated by the Nrf-2/Keap-1 signaling pathway. In particular, we investigate the E₂-induced expression and cellular distribution of DPP III monozinc exopeptidase, a member of the Nrf-2/Keap-1 pathway, upon hyperoxia treatment.

We find that DPP III accumulates in the nucleus in response to hyperoxia. Further, we show that combined induction of hyperoxia and E₂ administration have an additive effect on the nuclear accumulation of DPP III. The level of nuclear accumulation of DPP III is comparable to nuclear accumulation of Nrf-2 in healthy female mice exposed to hyperoxia. In ovariectomized females exposed to hyperoxia, supplementation of E₂ induced upregulation of DPP III, Ho-1, Sirt-1 and downregulation of Ppar-γ. While other cytoprotective mechanisms cannot be excluded, these findings demonstrate a prominent role of DPP III, along with Sirt-1, in the E₂-mediated protection against hyperoxia.

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DPP III accumulates in the nucleus in response to hyperoxia.

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Additive effect of hyperoxia and E₂ on nuclear accumulation of DPP III is observed.

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Protective effect of E₂ is associated with increased DPP III, Ho-1 and Sirt-1.

Impacts of gentamycin toxicity: nephroprotective role of guarana through different signaling pathways

Gentamicin is a widely used aminoglycosidic antibiotic since its discovery. Like any other medication gentamicin causes unwanted side effects such as hepatotoxicity and nephrotoxicity. This study aims to examine the antioxidant effect of the guarana seed extract in protecting renal tissue. Forty male mice were divided into four groups (group one was control with free access to food and water, group two was treated orally with 300 mg/kg of guarana seed extract daily, group three was injected intraperitoneally with 100 mg/kg of gentamicin daily and the fourth group was co-treated with both 300 mg/kg of guarana seed extract orally and injected intraperitoneally with 100 mg/kg of gentamicin daily) for two weeks. Serum levels of urea, creatinine, AST, ALT, IL-1β and IL-6 have significantly elevated in the gentamicin treated group and those changes were not found in the guarana co-treated group. In gentamicin treated mice, a significant reduction was observed in two antioxidants SOD and GPX accompanied by downregulation of Ho-1 and Nrf2 while, that did not happen in the guarana seed extract co-treated group. Histopathology and immunohistochemistry slides show that the guarana seed extract prevents degenerative and necrotic events in tubular epithelial tissues caused by gentamicin toxicity. In conclusion, current data suggest that gentamicin can damage renal tissues when given at 100 mg/kg/day, however, the guarana seed extract may be capable of preventing that event when cotreated with the gentamicin as a supplement.