Sirt6 promotes DNA damage repair in osteoarthritis chondrocytes by activating the Keap1/Nrf2/HO-1 signaling pathway

The aim of this study was to explore the effect and mechanism of Sirt6 on DNA damage repair in OA chondrocytes. Cartilage tissues were collected from OA patients with knee arthroplasty and traumatic amputation patients without OA. Besides, 7-week-old male C57BL/6 mice were randomly divided into Control and OA groups; CHON-001 cells of corresponding groups were treated with 10 ng/ml interleukin (IL)-1β, respectively. Subsequently, Sirt6 or siNrf2 was over-expressed in CHON-001 cells to observe the effect of Sirt6 on DNA damage and senescence of chondrocytes by IL-1β through the nuclear factor E2-related factor 2 (Nrf2) signaling pathway. The expression level of Sirt6 in human and mouse OA cartilage tissues was significantly decreased. However, 24 h of treatment with IL-1β significantly decreased the expression of Sirt6 in chondrocytes, induced DNA damage, and promoted cellular senescence. In addition, over-expression of Sirt6 promoted DNA damage repair and inhibited cellular senescence in IL-1β-induced chondrocytes. Moreover, the overexpression of Sirt6 activated the Keap1/Nrf2/HO-1 signaling pathway in chondrocytes, while knockdown of Nrf2 expression inhibited the DNA damage repair and anti-senescence effects of Sirt6 on IL-1β-treated chondrocytes. Sirt6 may reduce DNA damage and cellular senescence in OA chondrocytes induced by IL-1β through activating the Keap1/Nrf2/HO-1 signaling pathway.

Wound Healing versus Metastasis: Role of Oxidative Stress

Many signaling pathways, molecular and cellular actors which are critical for wound healing have been implicated in cancer metastasis. These two conditions are a complex succession of cellular biological events and accurate regulation of these events is essential. Apart from inflammation, macrophages-released ROS arise as major regulators of these processes. But, whatever the pathology concerned, oxidative stress is a complicated phenomenon to control and requires a finely tuned balance over the different stages and responding cells. This review provides an overview of the pivotal role of oxidative stress in both wound healing and metastasis, encompassing the contribution of macrophages. Indeed, macrophages are major ROS producers but also appear as their targets since ROS interfere with their differentiation and function. Elucidating ROS functions in wound healing and metastatic spread may allow the development of innovative therapeutic strategies involving redox modulators.

Cullin 3 mutant causing familial hyperkalemic hypertension lacks normal activity in the kidney

Mutations in the ubiquitin ligase scaffold protein cullin 3 (CUL3) cause the disease familial hyperkalemic hypertension (FHHt). We recently reported that in the kidney, aberrant mutant CUL3 (CUL3-Δ9) activity lowers the abundance of CUL3-Δ9 and Kelch-like 3, the CUL3 substrate adaptor for with-no-lysine kinase 4 (WNK4) and that this is mechanistically important. However, whether CUL3-Δ9 exerts additional effects on other targets that may alter renal function is unclear. Here, we sought to determine 1) whether CUL3-Δ9 expression can rescue the phenotype of renal tubule-specific Cul3 knockout mice, and 2) whether CUL3-Δ9 expression affects other CUL3 substrates. Using an inducible renal tubule-specific system, we studied two CUL3-Δ9-expressing mouse models: Cul3 knockout (Cul3-/-/Δ9) and Cul3 heterozygous background (Cul3+/-/Δ9, FHHt model). The effects of CUL3-Δ9 in these mice were compared with Cul3-/- and Cul3+/- mice. Similar to Cul3-/- mice, Cul3-/-/Δ9 mice displayed polyuria with loss of aquaporin 2 and collecting duct injury; proximal tubule injury also occurred. CUL3-Δ9 did not promote degradation of two CUL3 targets that accumulate in the Cul3-/- kidney: high-molecular-weight (HMW) cyclin E and NAD(P)H:quinone oxidoreductase 1 (NQO1) [a surrogate for the CUL3-Kelch-like ECH-associated protein 1 (KEAP1) substrate nuclear factor erythroid-2-related factor 2]. Since CUL3-Δ9 expression cannot rescue the Cul3-/- phenotype, our data suggest that CUL3-Δ9 cannot normally function in ubiquitin ligase complexes. In Cul3+/-/Δ9 mice, KEAP1 abundance did not differ but NQO1 abundance was higher, suggesting adaptor sequestration by CUL3-Δ9 in vivo. Together, our results provide evidence that in the kidney, CUL3-Δ9 completely lacks normal activity and can trap CUL3 substrate adaptors in inactive complexes.NEW & NOTEWORTHY CUL3 mutation (CUL3-Δ9) causes familial hyperkalemic hypertension (FHHt) by reducing adaptor KLHL3, impairing substrate WNK4 degradation. Whether CUL3-Δ9 affects other targets in kidneys remains unclear. We found that CUL3-Δ9 cannot degrade two CUL3 targets, cyclin E and nuclear factor erythroid-2-related factor 2 (NRF2; using a surrogate marker NQO1), or rescue injury or polyuria caused by Cul3 disruption. In an FHHt model, CUL3-Δ9 impaired NRF2 degradation without reduction of its adaptor KEAP1. Our data provide additional insights into CUL3-Δ9 function in the kidney.

Downregulation of P300/CBP-Associated Factor Protects from Vascular Aging via Nrf2 Signal Pathway Activation

Increasing evidence has shown that vascular aging has a key role in the pathogenesis of vascular diseases. P300/CBP-associated factor (PCAF) is involved in many vascular pathological processes, but the role of PCAF in vascular aging is unknown. This study aims to explore the role and underlying mechanism of PCAF in vascular aging. The results demonstrated that the expression of PCAF was associated with age and aging, and remarkably increased expression of PCAF was present in human atherosclerotic coronary artery. Downregulation of PCAF could reduce angiotensin II (AngII)-induced senescence of rat aortic endothelial cells (ECs) in vitro. In addition, inhibition of PCAF with garcinol alleviated AngII-induced vascular senescence phenotype in mice. Downregulation of PCAF could alleviate AngII-induced oxidative stress injury in ECs and vascular tissue. Moreover, PCAF and nuclear factor erythroid-2-related factor 2 (Nrf2) could interact directly, and downregulation of PCAF alleviated vascular aging by promoting the activation of Nrf2 and enhancing the expression of its downstream anti-aging factors. The silencing of Nrf2 with small interfering RNA attenuated the protective effect of PCAF downregulation from vascular aging. These findings indicate that downregulation of PCAF alleviates oxidative stress by activating the Nrf2 signaling pathway and ultimately inhibits vascular aging. Thus, PCAF may be a promising target for aging-related cardiovascular disease.

Hydrogen exerts neuroprotective effects by inhibiting oxidative stress in experimental diabetic peripheral neuropathy rats

Diabetic peripheral neuropathy (DPN) is a complex disorder caused by long-standing diabetes. Oxidative stress was considered the critical creed in this DPN pathophysiology. Hydrogen has antioxidative effects on diabetes mellitus and related complications. However, there is still no concern on the beneficial effects of hydrogen in DPN. This paper aimed to evaluate the effects of exogenous hydrogen to reduce the severity of DPN in streptozotocin-induced diabetic rats. Compared with hydrogen-rich saline treatment, hydrogen inhalation significantly reduced blood glucose levels in diabetic rats in the 4^th and 8^th weeks. With regard to nerve function, hydrogen administration significantly attenuated the decrease in the velocity of motor nerve conduction in diabetic animals. In addition, hydrogen significantly attenuated oxidative stress by reducing the level of malondialdehyde, reactive oxygen species, and 8-hydroxy-2-deoxyguanosine and meaningfully enhanced the antioxidant capability by partially restoring the activities of superoxide dismutase. Further studies showed that hydrogen significantly upregulated the expression of nuclear factor erythroid-2-related factor 2 and downstream proteins such as catalase and hemeoxygenase-1 in the nerves of diabetic animals. Our paper showed that hydrogen exerts significant protective effects in DPN by downregulating oxidative stress via the pathway of nuclear factor erythroid-2-related factor 2, which suggests its potential value in clinical applications.

Ginkgo biloba protects striatal neurodegeneration and gut phagoinflammatory damage in rotenone-induced mice model of Parkinson's disease: Role of executioner caspase-3/Nrf2/ARE signaling

Asymptomatic and early clinical stages of Parkinson's disease (PD) have been linked with comorbid non-motor symptoms including dysfunction of the gastrointestinal (GI) tract. Notwithstanding, neuroprotective and gastroprotective effects of Ginkgo biloba supplements (GBS) have been investigated independently. Hence, whether GBS-mediated GIT-protective capacity could be helpful in PD via gut-brain anti-inflammatory signaling still remains unknown. Treatment with GBS significantly repressed the motor behavioral and neuromuscular deficits and prevented loss of striatal dopaminergic loss by improving the level of tyrosine hydroxylase enzyme and suppressing synucleinopathy development. Striatal neurons and ileal epithelial injury following intraperitoneal rotenone administration were accompanied with oxidoinflammatory/nitroinflammatory stress and marked inhibition of cholinergic transmission. Moreover, there was increased striatal executioner caspase-3 and decreased nuclear factor erythroid-2-related factor 2 (Nrf2) immunoexpression, loss of striatal pyramidal neuron with a marked decrease in length and width of the dendritic spines as well as significant hyperplasia of cryptal cells in the ileal epithelial tissues, all which were reversed by the pretreatment + concurrent (Pre-CONC) and concurrent (CONC) GBS treatment pattern. In sum, we proved the potential dual effects of GBS in preventing both dopaminergic neural-related impairments and gut wall abnormalities linked with PD.

Korean Red Ginseng Extract Inhibits IL-8 Expression via Nrf2 Activation in Helicobacter pylori-Infected Gastric Epithelial Cells

Helicobacter pylori (H. pylori) causes gastric diseases by increasing reactive oxygen species (ROS) and interleukin (IL)-8 expression in gastric epithelial cells. ROS and inflammatory responses are regulated by the activation of nuclear factor erythroid-2-related factor 2 (Nrf2) and the expression of Nrf2 target genes, superoxide dismutase (SOD) and heme oxygenase-1 (HO-1). We previously demonstrated that Korean red ginseng extract (RGE) decreases H. pylori-induced increases in ROS and monocyte chemoattractant protein 1 in gastric epithelial cells. We determined whether RGE suppresses the expression of IL-8 via Nrf2 activation and the expression of SOD and HO-1 in H. pylori-infected gastric epithelial AGS cells. H. pylori-infected cells were treated with RGE with or without ML385, an Nrf2 inhibitor, or zinc protoporphyrin (ZnPP), a HO-1 inhibitor. Levels of ROS and IL-8 expression; abundance of Keap1, HO-1, and SOD; levels of total, nuclear, and phosphorylated Nrf2; indices of mitochondrial dysfunction (reduction in mitochondrial membrane potential and ATP level); and SOD activity were determined. As a result, RGE disturbed Nrf2–Keap1 interactions and increased nuclear Nrf2 levels in uninfected cells. H. pylori infection decreased the protein levels of SOD-1 and HO-1, as well as SOD activity, which was reversed by RGE treatment. RGE reduced H. pylori-induced increases in ROS and IL-8 levels as well as mitochondrial dysfunction. ML385 or ZnPP reversed the inhibitory effect of RGE on the alterations caused by H. pylori. In conclusion, RGE suppressed IL-8 expression and mitochondrial dysfunction via Nrf2 activation, induction of SOD-1 and HO-1, and reduction of ROS in H. pylori-infected cells.

A Mixture of Topical Forms of Polydeoxyribonucleotide, Vitamin C, and Niacinamide Attenuated Skin Pigmentation and Increased Skin Elasticity by Modulating Nuclear Factor Erythroid 2-like 2

It is well-known that increased oxidative stress caused by ultraviolet B (UV-B) radiation induces melanogenesis and activates metalloproteinases (MMPs), which degrade collagen and elastin fibers, leading to decreased skin elasticity. Various antioxidant agents, such as vitamin C and niacinamide, have been evaluated for use as treatments for photoaging or skin pigmentation. In this study, we evaluated the ability of a topical liquid formula of polydeoxyribonucleotide (PDRN), vitamin C, and niacinamide (PVN) delivered via a microneedling therapy system (MTS) to attenuate photoaging and pigmentation by increasing nuclear factor erythroid 2-like 2 (NRF2)/heme oxygenase-1 (HO-1) and decreasing MMP expression in a UV-B-radiated animal model. The effects of the PVN were compared with those of individual PDRN and hydroquinone (HQ) compounds. The expression of NRF2/HO-1 significantly increased in response to HQ, PDRN, and PVN in UV-B-radiated animal skin. The activity of nicotinamide adenine dinucleotide phosphate hydrogen oxidase decreased in response to HQ, PDRN, and PVN, and the superoxide dismutase activity increased. The expression of tumor protein p53 and microphthalmia-associated transcription factor and tyrosinase activity decreased in response to HQ, PDRN, and PVN, and this decrease was accompanied by decreased melanin content in the skin. The expression of nuclear factor kappa-light-chain enhancer of activated B cells and MMP2/3/9 decreased in response to HQ, PDRN, and PVN in UV-B-radiated skin. However, the expression of collagen type I α1 chain and the amount of collagen fibers that were evaluated by Masson’s trichrome staining increased in response to HQ, PDRN, and PVN. The contents of elastin fibers, fibrillin 1/2 and fibulin 5 increased in response to HQ, PDRN, and PVN. In conclusion, PVN delivered via MTS led to decreased melanogenesis and destruction of collagen and elastin fibers by MMPs, and, thus, PVN decreased skin pigmentation and increased skin elasticity.

Enzyme-Treated Zizania latifolia Extract Protects against Alcohol-Induced Liver Injury by Regulating the NRF2 Pathway

Binge drinking patterns easily produce a state of oxidative stress that disturbs liver function. Eventually, this leads to alcoholic liver disease. A safe and effective therapy for alcoholic liver disease remains elusive. Enzyme-treated Z. latifolia extract (ETZL) was studied as a potential agent for treating alcohol-induced liver disease. In addition, its underlying mechanisms were elucidated. In the binge model, ETZL was pretreated with alcohol (5 g/kg) three times at 12-h intervals. Our results showed that ETZL pretreatment decreased the serum levels of ALT, AST, ALP, and TG. ETZL treatment appeared to prevent an increase in hepatic TG and MDA levels, and there was a decrease in total GSH following alcohol treatment. Histopathological examination showed that lipid droplets were significantly reduced in the ETZL group compared to the control group. ETZL also exhibited radical scavenging activity. It significantly reduced t-BHP-induced cytotoxicity and the production of reactive oxygen species (ROS) in HepG2 cells. ETZL also enhanced NRF2 nuclear translocation and increased expression of the downstream target genes HO-1, NQO1, and GCLC as an antioxidant defense. Finally, ETZL treatment significantly reduced cell death. Our study suggests that ETZL ameliorates binge ethanol-induced liver injury by upregulating the antioxidant defense mechanism.

Nuclear Factor Erythroid-2-related Factor 2 Gene Polymorphisms in Vitiligo

BACKGROUND

Oxidative stress is now one of the accepted theories of vitiligo development. Nuclear factor erythroid-2-related factor 2 (Nrf2) regulates the expression of antioxidant proteins.

OBJECTIVE

This work aimed to evaluate the association of Nrf2 gene polymorphisms with the susceptibility to vitiligo among a sample of Egyptian patients with vitiligo.

METHODS

This case-control study included 100 patients with vitiligo and 50 healthy matched volunteers serving as a control group. Genotyping was carried out by real-time polymerase chain reaction.

RESULTS

The frequencies of TT, CT, and combined (TT+CT) genotypes and the T allele of Nrf2 (rs35652124) were significantly increased in the studied patients with vitiligo relative to the healthy controls (p<0.001, p=0.012, p<0.001 and p<0.001, respectively). There was a nonsignificant difference between patients and controls regarding Nrf2 (rs6721961) genotypes. However, the T allele of Nrf2 (rs6721961) was significantly predominant in the studied patients compared to in the controls (p=0.029). Among the studied criteria, the T allele of Nrf2 (rs6721961) was predominant in patients with a marginal type of repigmentation (p=0.022), while the G allele of the same single-nucleotide polymorphism was associated with a higher body mass index value (p=0.034). One hundred percent of patients with vitiligo with the Nrf2 (rs6721961) GT genotype had a progressive disease course (p=0.015).

CONCLUSION

Nrf2 (-617 T/G) and (-653 T/C) polymorphism might play a role in patient susceptibility to vitiligo and modify the clinical presentation of the disease.

Docosahexaenoic Acid Induces Expression of NAD(P)H: Quinone Oxidoreductase and Heme Oxygenase-1 through Activation of Nrf2 in Cerulein-Stimulated Pancreatic Acinar Cells

Oxidative stress is a major risk factor for acute pancreatitis. Reactive oxygen species (ROS) mediate expression of inflammatory cytokines such as interleukin-6 (IL-6) which reflects the severity of acute pancreatitis. The nuclear factor erythroid-2-related factor 2 (Nrf2) pathway is activated to induce the expression of antioxidant enzymes such as NAD(P)H: quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1) as a cytoprotective response to oxidative stress. In addition, binding of Kelch-like ECH-associated protein 1 (Keap1) to Nrf2 promotes degradation of Nrf2. Docosahexaenoic acid (DHA)—an omega-3 fatty acid—exerts anti-inflammatory and antioxidant effects. Oxidized omega-3 fatty acids react with Keap1 to induce Nrf2-regulated gene expression. In this study, we investigated whether DHA reduces ROS levels and inhibits IL-6 expression via Nrf2 signaling in pancreatic acinar (AR42J) cells stimulated with cerulein, as an in vitro model of acute pancreatitis. The cells were pretreated with or without DHA for 1 h and treated with cerulein (10⁻⁸ M) for 1 (ROS levels, protein levels of NQO1, HO-1, pNrf2, Nrf2, and Keap1), 6 (IL-6 mRNA expression), and 24 h (IL-6 protein level in the medium). Our results showed that DHA upregulates the expression of NQO1 and HO-1 in cerulein-stimulated AR42J cells by promoting phosphorylation and nuclear translocation of Nrf2. DHA increased interaction between Keap1 and Nrf2 in AR42J cells, which may increase Nrf2 activity by inhibiting Keap1-mediated sequestration of Nrf2. In addition, DHA-induced expression of NQO1 and HO-1 is related to reduction of ROS and IL-6 levels in cerulein-stimulated AR42J cells. In conclusion, DHA inhibits ROS-mediated IL-6 expression by upregulating Nrf2-mediated expression of NQO1 and HO-1 in cerulein-stimulated pancreatic acinar cells. DHA may exert positive modulatory effects on acute pancreatitis by inhibiting oxidative stress and inflammatory cytokine production by activating Nrf2 signaling in pancreatic acinar cells.

Influence of a combination of triptolide and ferulic acid on the activities of CYP450 enzymes and oxidative stress in HaCaT cells

Topical administration of triptolide (TP) is effective in the treatment of rheumatoid arthritis (RA), but it can also induce skin irritation. Previous studies have used data mining strategies to analyze the application of Tripterygium wilfordii in the treatment of RA and have shown that TP and ferulic acid (FA) can be used in combination due to their component compatibility. The aims of the present study were to investigate the mechanisms underlying the effects of TP treatment and to identify its effects on metabolism and oxidative damage in the skin. MTT assay results suggested that the HaCaT cell survival rate was significantly increased when the compatibility ratio of TP to FA was 1:100. Moreover, the combination of TP with FA (TP + FA) did not significantly affect the activities of the cytochrome P40 (CYP) enzymes CYP family 1 subfamily A member 2 (CYP1A2), CYP2E1 and CYP3A4, when used as a 'cocktail'. It was found that TP + FA significantly decreased the production levels of reactive oxygen species (ROS), superoxide dismutase and malondialdehyde in HaCaT cells, while significantly increasing levels of glutathione and catalase. In addition, TP + FA significantly increased nuclear factor erythroid 2-related factor 2 protein expression, compared with TP alone. Thus, the present results indicated that the underlying mechanism of TP + FA efficacy may be related to decreased ROS production level in HaCaT cells, increased production levels of key antioxidant factors and increased antioxidant activity of the epidermis, all of which were correlated with a protective effect against oxidative damage.

Alpha-lipoic acid: A possible pharmacological agent for treating dry eye disease and retinopathy in diabetes

Alpha-lipoic acid (ALA) is a naturally occurring dithiol micronutrient which acts as a cofactor for mitochondrial enzyme activity. Due to its potential antioxidant activity, it is considered as "universal antioxidant". Previous studies reported the pharmacological benefits of ALA such as glycaemic control, improved insulin sensitivity and alleviation of diabetic complications such as neuropathy and cardiovascular diseases. Dry eye disease and retinopathy are prevalent in diabetic patients. Experimental studies demonstrated the beneficial effects of ALA in dry eye and diabetic retinopathy. ALA can prevent the dry eye by down regulating the expression of matrix metalloproteinase-9 in the corneal epithelial cells and activating the antioxidant status of the ocular surface. Furthermore, its direct antioxidant effect can also prevent oxidative stress-induced corneal surface erosion and lachrymal gland damage. ALA prevents diabetic retinopathy through inhibition of O-linked β-N-acetylglucosamine transferase and nuclear factor-kappa B activity and alleviation of oxidative stress. It can activate the nuclear factor erythroid-2-related factor 2 and AMP-activated protein kinase in retinal ganglion cells. Clinical trials conducted in pre-retinopathic diabetic patients showed ALA with genistein and vitamins could protect the retinal cells and decline the inflammatory effect in diabetic patients. However, studies are scant to explore its beneficial effects in dry eye disease and diabetic retinopathy. Therefore, this review article discusses an update on the role of ALA in dry eye disease and diabetic retinopathy, two ocular diseases prevalent in diabetic patients.

Hyperoside Protected Against Oxidative Stress-Induced Liver Injury via the PHLPP2-AKT-GSK-3β Signaling Pathway In Vivo and In Vitro

Hyperoside, isolated from Drosera rotundifolia L., seeds of Cuscuta chinensis Lam., or Hypericum perforatum L., originally showed to possess an antifungal and antibacterial activity, while recently showed the protective effects against oxidative stress-induced liver injury. This study investigated such a protective effect of hyperoside and the underlying molecular mechanisms in vitro and in carbon tetrachloride (CCl4)-injured rat livers. The data showed that hyperoside was able to prevent the oxidative stress-induced liver morphological changes and CCl4-induced rat liver injury. Hyperoside reversed the decrease of superoxidase dismutase (SOD) level and the increase of malondialdehyde (MDA) level in vivo. Moreover, hyperoside regulated the pleckstrin homology (PH) domain leucine-rich repeat protein phosphatase 2 (PHLPP2)-protein kinase B (AKT)-glycogen synthase kinase 3β (GSK-3β) signaling pathway in tert-butylhydroquinone (t-BHP)-treated liver cells, e.g., Hyperoside reduced PHLPP2 expression to activate AKT phosphorylation, induce GSK-3β phosphorylation, and then increased nuclear factor erythroid-2-related factor 2 (Nrf2) nuclear translocation, reduced nuclear translocation of phosphorylated Fyn, and promoted heme oxygenase-1 (HO-1) expression in vivo and in vitro. In contrast, siRNA-mediated knockdown of PHLPP2 expression enhanced hyperoside-mediated activation of the AKT-GSK-3β kinase pathway in liver cells. In conclusion, the present study demonstrated that hyperoside could protect against oxidative stress-induced liver injury by regulating the PHLPP2-AKT-GSK-3β signaling pathway in vivo and in vitro.

Cellular Redox-Related Transcription Factor Nrf2 Mediation of HaTrf Response to Host Plant Allelochemical 2-Tridecanone in Helicoverpa armigera

Despite there being a number of excellent studies on detoxification enzyme-mediated interaction between insect and plant allelochemical, there are no reports on the pathway of the transferrin effect in insect response to host plant allelochemical. Our research indicates that Helicoverpa armigera transferrin (HaTrf) inhibited the apoptotic cell death treated by 2-tridecanone, a host plant allelochemical present in tomato species (Lycopersicon hirsutum f. glabratum), by cellular redox-related transcription factor nuclear factor erythroid-2-related factor 2 (Nrf2). Nrf2 can defend organisms against the detrimental effects of oxidative stress and play pivotal roles in preventing host plant allelochemical-related toxicity. This study explains how HaTrf inhibited the apoptotic cell death during exposure to host plant allelochemical 2-tridecanone and provides a novel view on transferrin and its anti-apoptotic role in plant-insect interactions.

Geniposide alleviates non-alcohol fatty liver disease via regulating Nrf2/AMPK/mTOR signalling pathways

Non-alcohol fatty liver disease (NAFLD) is a common disease which causes serious liver damage. Geniposide (GEN), a kind of iridoid glycoside extracted from Gardenia jasminoides fruit, has many biological effects, such as resistance to cell damage and anti-neurodegenerative disorder. Lipid accumulation was obvious in tyloxapol-induced liver and oil acid (OA) with palmitic acid (PA)-induced HepG2 cells compared with the control groups while GEN improved the increasing conditions. GEN significantly lessened the total cholesterol (TC), the triglyceride (TG), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), myeloperoxidase (MPO), reactive oxygen species (ROS) and increased high-density lipoprotein (HDL), superoxide dismutase (SOD) to response the oxidative stress via activating nuclear factor erythroid-2-related factor 2 (Nrf2), haeme oxygenase (HO)-1 and peroxisome proliferator-activated receptor (PPAR)α which may influence the phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK) signalling pathway in mice and cells. Additionally, GEN evidently decreased the contents of sterol regulatory element-binding proteins (SREBP)-1c, phosphorylation (P)-mechanistic target of rapamycin complex (mTORC), P-S6K, P-S6 and high mobility group protein (HMGB) 1 via inhibiting the expression of phosphoinositide 3-kinase (PI3K), and these were totally abrogated in Nrf2-/- mice. Our study firstly proved the protective effect of GEN on lipid accumulation via enhancing the ability of antioxidative stress and anti-inflammation which were mostly depend on up-regulating the protein expression of Nrf2/HO-1 and AMPK signalling pathways, thereby suppressed the phosphorylation of mTORC and its related protein.

Galanthamine improves myocardial ischemia-reperfusion-induced cardiac dysfunction, endoplasmic reticulum stress-related apoptosis, and myocardial fibrosis by suppressing AMPK/Nrf2 pathway in rats

Background

Myocardial ischemia/reperfusion (I/R) injury is an important cause of myocardial infarction and heart failure after cardiovascular surgery. Galanthamine (Gal) is an important Amaryllidaceae alkaloid with anti-acetylcholinesterase and anti-inflammatory activity. The purpose of this study was to investigate the role of Gal in myocardial I/R injury.

Methods

In this study, an animal model of myocardial I/R injury was constructed, and the rats were divided into five groups (n=10): the sham, I/R model, I/R + Gal (1 mg/kg), I/R + Gal (3 mg/kg), and I/R + Aspirin (20 mg/kg) groups. The expression of related proteins was detected by Western blotting and Immunohistochemistry, and Histological lesion was detected by HE staining.

Results

Results showed that Gal improves I/R-induced cardiac dysfunction in rats. Moreover, Gal inhibits I/R-induced endoplasmic reticulum stress (ERS)-related apoptosis by suppressing the expression of CHOP, Cleaved caspase 12, and caspase 3, and promoting the expression of CADD34 and BiP in rats. Furthermore, Gal mitigates I/R-induced myocardial fibrosis through restraining the expression of α-SMA and Collagen I in rats. Mechanically, Gal promoted the expression of AMPKα1, Nrf2 and HO-1. However, AMPK inhibitor Compound C exhibited the opposite effects. Collectively, this finding suggests that Gal improves I/R-induced cardiac dysfunction, ERS-related apoptosis, and myocardial fibrosis by activating AMPK/Nrf2 pathway in myocardial I/R rats.

Conclusions

Given this evidence, Gal may be a potential therapeutic drug for the treatment of I/R injury.

α-Lipoic Acid Inhibits IL-8 Expression by Activating Nrf2 Signaling in Helicobacter pylori-infected Gastric Epithelial Cells

Helicobacter pylori (H. pylori) causes gastritis and gastric cancers. Oxidative stress is involved in the pathological mechanism of H. pylori-induced gastritis and gastric cancer induction. Therefore, reducing oxidative stress may be beneficial for preventing the development of H. pylori-associated gastric diseases. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a crucial regulator for the expression of antioxidant enzyme heme oxygenase-1 (HO-1), which protects cells from oxidative injury. α-Lipoic acid (α-LA), a naturally occurring dithiol, shows antioxidant and anti-inflammatory effects in various cells. In the present study, we examined the mechanism by which α-LA activates the Nrf2/HO-1 pathway, suppresses the production of pro-inflammatory cytokine interleukine-8 (IL-8), and reduces reactive oxygen species (ROS) in H. pylori-infected AGS cells. α-LA increased the level of phosphorylated and nuclear-translocated Nrf2 by decreasing the amount of Nrf2 sequestered in the cytoplasm by complex formation with Kelch-like ECH1-associated protein 1 (KEAP 1). By using exogenous inhibitors targeting Nrf2 and HO-1, we showed that up-regulation of activated Nrf2 and of HO-1 results in the α-LA-induced suppression of interleukin 8 (IL-8) and ROS. Consumption of α-LA-rich foods may prevent the development of H. pylori-associated gastric diseases by decreasing ROS-mediated IL-8 expression in gastric epithelial cells.

Rapid or Slow Time to Brain Death? Impact on Kidney Graft Injuries in an Allotransplantation Porcine Model

The use of donors deceased after brain death (DBD) with extended criteria in response to the shortage of grafts leads to the removal of more fragile kidneys. These grafts are at greater risk of not being grafted or delayed function. A better knowledge of the pathophysiology of DBDs would improve this situation. There is a difference between the results from animal models of DBD and the clinical data potentially explained by the kinetics of brain death induction. We compared the effect of the induction rate of brain death on the recovery of post-transplant renal function in a pig model of DBD followed by allografts in nephrectomized pigs. Resumption of early function post-transplant was better in the rapidly generated brain death group (RgBD) and graft fibrosis at three months less important. Two groups had identical oxidative stress intensity but a greater response to this oxidative stress by SIRT1, PGC1-α and NRF2 in the RgBD group. Modulation of mechanistic target of rapamycin (mTOR) stimulation by NRF2 would also regulate the survival/apoptosis balance of renal cells. For the first time we have shown that an allostatic response to oxidative stress can explain the impact of the rapidity of brain death induction on the quality of kidney transplants.

Chrysanthemum extract attenuates hepatotoxicity via inhibiting oxidative stress in vivo and in vitro

Background

‘Bianliang ziyu’, a famous chrysanthemum variety commonly planted in Kaifeng, China, is often consumed by local residents. However, the hepatoprotective effects of Bianliang ziyu and their underlying mechanisms are not clear.

Objective

In this study, we investigated the hepatoprotective and antioxidative effects of Bianliang ziyu extract (BZE) on liver injury and explored its molecular mechanisms.

Design

Sprague-Dawley rats were administered BZE by intragastric administration for 8–9 days, and then alcohol or carbon tetrachloride (CCl₄) was administered by gavage to induce acute liver injury. The activities of serum alanine aminotransferase, aspartate aminotransferase, superoxide dismutase, and malondialdehyde in the rats were measured, and the liver of each rat was examined for histopathological changes. In vitro, HL-7702 cells were pretreated with BZE for 24 h and then exposed to 30 mmol•L⁻¹ acetaminophen (APAP) for 12 h. The survival rate of the cells and the alanine aminotransferase and aspartate aminotransferase activities were determined. Then, we investigated the effects of BZE on oxidative stress, apoptosis, and the activation of nuclear factor erythroid-2-related factor 2 (Nrf2) signaling in HL-7702 cells induced by APAP.

Results

The results showed that BZE prevented alcohol-, CCl₄-, and APAP-induced liver injury and suppressed hepatic oxidative stress in vitro and in vivo. BZE was also observed to significantly inhibit the reduction of mitochondrial membrane potential and regulate the expression of Bcl-2, Bax and Caspase-3 in APAP-induced HL-7702 cells. In addition, BZE significantly promoted nuclear translocation and the expression of Nrf2 as well as its downstream gene hemeoxygenase-1 (HO-1) in vitro. Furthermore, the findings showed that Nrf2 siRNA reversed the effects of BZE on cell survival and apoptosis-related protein expression in APAP-induced HL-7702 cells.

Conclusions

BZE plays an important role in preventing hepatotoxicity by inhibiting oxidative stress and apoptosis through activation of Nrf2 signaling. BZE could be developed as an effective functional food for protecting the liver.

Curcumin attenuates hypoxic-ischemic brain injury in neonatal rats through induction of nuclear factor erythroid-2-related factor 2 and heme oxygenase-1

Curcumin has previously demonstrated anti-inflammatory, anti-infective and immuno-suppressive effects. In the present study, whether the attenuating effects of curcumin against hypoxic-ischemic brain injury in neonatal rats are mediated via nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was investigated. A model of hypoxic-ischemic brain injury was created using 1-week-old Sprague Dawley rats (weight, 52±1 g). The model rats were treated with 150 mg/kg curcumin by gavage for 3 days. Malondialdehyde levels, and superoxide dismutase and caspase-3 activities were assayed using commercial kits and western blot analysis was used to measure inducible nitric oxide synthase (iNOS), Nrf2 and HO-1 expression levels. Treatment with curcumin effectively reduced the brain injury score, increased myelin basic protein (MBP) expression and increased the quantity of neuronal cells in neonatal rats with hypoxic-ischemic brain injury. Furthermore, treatment with curcumin significantly attenuated the changes in SOD activity and MDA levels and suppressed the iNOS protein expression induced in neonatal rats by hypoxic-ischemic brain injury. Treatment with curcumin significantly increased Nrf2 and HO-1 expression in the neonatal rats with hypoxic-ischemic brain injury. The present study indicated that curcumin attenuates hypoxic-ischemic brain injury in neonatal rats through the induction of Nrf2 and HO-1.

Fimasartan, a Novel Angiotensin-Receptor Blocker, Protects against Renal Inflammation and Fibrosis in Mice with Unilateral Ureteral Obstruction: the Possible Role of Nrf2

OBJECTIVES

A newly developed angiotensin II receptor blocker, fimasartan, is effective in lowering blood pressure through its action on the renin-angiotensin system. Renal interstitial fibrosis, believed to be due to oxidative injury, is an end-stage process in the progression of chronic kidney disease. Nuclear factor erythroid 2-related factor 2 (Nrf2) is known to regulate cellular oxidative stress and induce expression of antioxidant genes. In this study we investigated the role of Nrf2 in fimasartan-mediated antioxidant effects in mice with renal fibrosis induced by unilateral ureteral obstruction (UUO).

MATERIALS AND METHODS

UUO was induced surgically in mice, followed by either no treatment with fimasartan or the intraperitoneal administration of fimasartan (3 mg/kg/day). On day 7, we evaluated the changes in the renin-angiotensin system (RAS) and the expression of Nrf2 and its downstream antioxidant genes, as well as renal inflammation, apoptosis, and fibrosis in the obstructed kidneys. The effect of fimasartan on the Nrf2 pathway was also investigated in HK-2 cells stimulated by tumor necrosis factor-α.

RESULTS

The mice with surgically induced UUO showed increased renal inflammation and fibrosis as evidenced by histopathologic findings and total collagen content in the kidney. These effects were attenuated in the obstructed kidneys of the fimasartan-treated mice. Fimasartan treatment inhibited RAS activation and the expression of Nox1, Nox2, and Nox4. In contrast, fimasartan upregulated the renal expression of Nrf2 and its downstream signaling molecules (such as NQO1; HO-1; GSTa2 and GSTm3). Furthermore, it increased the expression of antioxidant enzymes, including CuSOD, MnSOD, and catalase. The fimasartan-treated mice had significantly less apoptosis on TUNEL staining, with decreased levels of pro-apoptotic protein and increased levels of anti-apoptotic protein. In the HK-2 cells, fimasartan treatment inhibited RAS activation, decreased expression of mitogen-activated protein kinases (MAPKs), and upregulated the Nrf2 pathway.

CONCLUSIONS

These results suggest that fimasartan has beneficial effects in reducing renal oxidative stress, inflammation, and fibrosis. Possible mechanisms to explain these effects are inhibition of RAS and MAPKs and upregulation of Nrf2 signaling, with subsequent induction of antioxidant pathways.