Nrf2 in alcoholic liver disease
Alcoholic liver disease (ALD) is a leading cause of morbidity and mortality of liver disorders and a major health issue globally. ALD refers to a spectrum of liver pathologies ranging from steatosis, steatohepatitis, fibrosis, cirrhosis and even hepatocellular carcinoma. Various mechanisms, including oxidative stress, protein and DNA modification, inflammation and impaired lipid metabolism, have been implicated in the pathogenesis of ALD. Further, reactive oxygen species (ROS) in particular, have been identified as a key component in the initiation and progression of ALD. Nuclear factor erythroid 2 like 2 (Nrf2) is a master regulator of the intracellular adaptive antioxidant response to oxidative stress, and aids in the detoxification of a variety of toxicants. Given its cytoprotective role, Nrf2 has been extensively studied as a therapeutic target for ALD. Paradoxically, however, emerging evidence have revealed that Nrf2 may be implicated in the progression of ALD. In this review, we summarize the role of Nrf2 in the development of ALD and discuss the underlying mechanisms. Clearly, more comprehensive studies with proper animal and cell models and in human are needed to verify the potential therapeutic role of Nrf2 in ALD.
Protective effect of the ethanol extract from Ligusticum chuanxiong rhizome against streptozotocin-induced diabetic nephropathy in mice
Rhizome of Ligusticum chuanxiong Hort. (Abbreviated as LC) is a frequently prescribed component in plenty of traditional Chinese medicine (TCM) formulas which are used to treat diabetic nephropathy (DN). The aims of the present study are to investigate the protective effect of the ethanol extract of LC rhizome (EEL) against DN in vivo, evaluate its potential mechanism, and find the evidence supporting its enthopharmacological use as an anti-DN agent.
Ramalin, an antioxidant compound derived from Antarctic lichen, prevents progression of liver fibrosis induced by dimethylnitrosamine (DNM) in rats
Hepatic fibrosis is characterized by the excessive accumulation of extracellular matrix (ECM), primarily collagen, within the liver. Because reactive oxygen species (ROS) has been implicated in its pathogenesis, the use of antioxidants as a potential treatment has been broadly explored. Here, we investigated the hepatoprotective properties of ramalin (RM), a compound extracted from the Antarctic lichen Ramalina terebrata, against hepatic fibrosis in vitro and in vivo. RM suppressed hepatic stellate cell (HSC) activation in vitro without any significant signs of adverse effects on the cells tested, and the accumulation of ECM was dramatically reduced in the liver tissue. Oral administration of RM in rats noticeably improved the gross appearance of the liver with increased body and liver weight relative to the DMN injected rats, and all of the serum biochemical markers returned to the normal range. RM treatment have ameliorated hepatic fibrosis in rats induced by DMN by repressing α-smooth muscle actin (α-SMA) and upregulating heme oxygenase-1 (HO-1). In addition, RM significantly reduced collagen accumulation, and levels of malondialdehyde (MDA) and hydroxyproline (HP) in the liver tissue of DMN injected rats. The efficacy exerted by RM was through erythroid 2-related factor 2 (Nrf2) mediated antioxidant response proteins such as HO-1 and NAD(P)H quinone dehydrogenase 1 (NQO-1). Our results show the beneficial effect of RM against the progression of hepatic fibrosis.
Protective effect of isochlorogenic acid B on liver fibrosis in non-alcoholic steatohepatitis of mice
Liver fibrosis is a common symptom of non-alcoholic steatohepatitis (NASH) and a worldwide clinical issue. The miR-122/HIF-1α signalling pathway is believed to play an important role in the genesis of progressive fibrosis. Isochlorogenic acid B (ICAB), naturally isolated from Laggera alata, is verified to have antioxidative and hepatoprotective properties. The aim of this study was to investigate the effect of ICAB on liver fibrosis in NASH and its potential protective mechanisms. NASH was induced in a mouse model with a methionine- and choline-deficient (MCD) diet for 4 weeks, and ICAB was orally administered every day at three doses (5, 10 and 20 mg/kg). Pathological results indicated that ICAB significantly improved the pathological lesions of liver fibrosis. The levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and hepatic hydroxyproline (Hyp), cholesterol (CHO), triglyceride (TG) were also significantly decreased by ICAB. In addition, ICAB inhibited hepatic stellate cells (HSCs) activation and the expressions of hepatic genes involved in liver fibrosis including LOX, TGF-β1, MCP-1, COL1α1 and TIMP-1. ICAB also attenuated liver oxidative stress through Nrf2 signalling pathway. What's more, the decreased levels of miR-122 and over-expression of hepatic HIF-1α could be reversed by ICAB treatment. These results simultaneously confirmed that ICAB had a significant protective effect on fibrosis in NASH by inhibiting oxidative stress via Nrf2 and suppressing multiple profibrogenic factors through miR-122/HIF-1α signalling pathway. This article is protected by copyright. All rights reserved.
Raf kinase inhibitor protein mediates myocardial fibrosis under conditions of enhanced myocardial oxidative stress
Fibrosis is a hallmark of maladaptive cardiac remodelling. Here we report that genome-wide quantitative trait locus (QTL) analyses in recombinant inbred mouse lines of C57BL/6 J and DBA2/J strains identified Raf Kinase Inhibitor Protein (RKIP) as genetic marker of fibrosis progression. C57BL/6 N-RKIP mice demonstrated diminished fibrosis induced by transverse aortic constriction (TAC) or CCl (carbon tetrachloride) treatment compared with wild-type controls. TAC-induced expression of collagen Iα2 mRNA, Ki67 fibroblasts and marker of oxidative stress 8-hydroxyguanosine (8-dOHG) fibroblasts as well as the number of fibrocytes in the peripheral blood and bone marrow were markedly reduced in C57BL/6 N-RKIP mice. RKIP-deficient cardiac fibroblasts demonstrated decreased migration and fibronectin production. This was accompanied by a two-fold increase of the nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2), the main transcriptional activator of antioxidative proteins, and reduced expression of its inactivators. To test the importance of oxidative stress for this signaling, C57BL/6 J mice were studied. C57BL/6 J, but not the C57BL/6 N-strain, is protected from TAC-induced oxidative stress due to mutation of the nicotinamide nucleotide transhydrogenase gene (Nnt). After TAC surgery, the hearts of Nnt-deficient C57BL/6 J-RKIP mice revealed diminished oxidative stress, increased left ventricular (LV) fibrosis and collagen Iα2 as well as enhanced basal nuclear expression of Nrf2. In human LV myocardium from both non-failing and failing hearts, RKIP-protein correlated negatively with the nuclear accumulation of Nrf2. In summary, under conditions of Nnt-dependent enhanced myocardial oxidative stress induced by TAC, RKIP plays a maladaptive role for fibrotic myocardial remodeling by suppressing the Nrf2-related beneficial effects.
Silybin Alleviates Hepatic Steatosis and Fibrosis in NASH Mice by Inhibiting Oxidative Stress and Involvement with the Nf-κB Pathway
Silybin is the major biologically active compound of silymarin, the standardized extract of the milk thistle (Silybum marianum). Increasing numbers of studies have shown that silybin can improve nonalcoholic steatohepatitis (NASH) in animal models and patients; however, the mechanisms underlying silybin's actions remain unclear.
A novel Gallic acid derivative attenuates BLM-induced pulmonary fibrosis in mice
Idiopathic Pulmonary fibrosis is a disease with high morbidity and mortality. Therefore, the development of new drugs is imperative. Gallic acid derivative is a derivative of Gallic acid that can be extracted from Chinese herbal medicine. In previous experiments, we found that Gallic acid derivative played dual roles in inflammatory and antioxidant activities. Meanwhile, Gallic acid derivative could inhibit the proliferation of lung fibroblast. In the present study, we investigated the function of Gallic acid derivative in inhibiting lung fibrosis. 5 mg/kg of bleomycin was administered to mice by a single intratracheal instillation. Three dosages of Gallic acid derivative (75 mg/kg, 150 mg/kg, 300 mg/kg) and Pirfenidone (80 mg/kg) were given to mice for 21 day. Gallic acid derivative treatment significantly reduced lung histological changes and decreased inflammatory cell infiltration. The content of collagen decreased with the decrease of hydroxyproline level. Analogously, the expression of alpha smooth muscle actin was reduced. Gallic acid derivative enhanced the antioxidant status, but reduced the expression of interleukin 6, NADPH oxidase-4. Our study proved that Gallic acid derivative reduced inflammation activation to some extent and could exert its effects through transforming growth factor β1/Smad2 signaling pathway and balancing NOX4/Nrf2.
Lipoic Acid Prevents High-Fat Diet-Induced Hepatic Steatosis in Goto Kakizaki Rats by Reducing Oxidative Stress Through Nrf2 Activation
Prevention of hepatic fat accumulation may be an important approach for liver diseases due to the increased relevance of hepatic steatosis in this field. This study was conducted to investigate the effects of the antioxidant α-lipoic acid (α-LA) on hepatic steatosis, hepatocellular function, and oxidative stress in a model of type 2 diabetes fed with a high fat diet (HFD). Goto-Kakizaki rats were randomly divided into four groups. The first group received only a standard rat diet (control GK) including groups 2 (HFD), 3 (vehicle group), and 4 (α-LA group), which were given HFD, ad libitum during three months. Wistar rats are the non-diabetic control group. Carbohydrate and lipid metabolism, liver function, plasma and liver tissue malondialdehyde (MDA), liver GSH, tumor necrosis factor-α (TNF-α) and nuclear factor E2 (erythroid-derived 2)-related factor-2 (Nrf2) levels were assessed in the different groups. Liver function was assessed using quantitative hepatobiliary scintigraphy, serum aspartate, and alanine aminotransferases (AST, ALT), alkaline phosphatase, gamma-glutamyltranspeptidase, and bilirubin levels. Histopathologically steatosis and fibrosis were evaluated. Type 2 diabetic animals fed with HFD showed a marked hepatic steatosis and a diminished hepatic extraction fraction and both were fully prevented with α-LA. Plasma and liver tissue MDA and hepatic TNF-α levels were significantly higher in the HFD group when compared with the control group and significantly lower in the α-LA group. Systemic and hepatic cholesterol, triglycerides, and serum uric acid levels were higher in hyperlipidemic GK rats and fully prevented with α-LA. In addition, nuclear Nrf2 activity was significantly diminished in GK rats and significantly augmented after α-LA treatment. In conclusion, α-LA strikingly ameliorates steatosis in this animal model of diabetes fed with HFD by decrementing the inflammatory marker TNF-α and reducing oxidative stress. α-LA might be considered a useful therapeutic tool to prevent hepatic steatosis by incrementing antioxidant defense systems through Nrf2 and consequently decreasing oxidative stress and inflammation in type 2 diabetes.
Sinapic acid ameliorates bleomycin-induced lung fibrosis in rats
Pulmonary fibrosis is a multifaceted disease with high mortality and morbidity, and it is commonly nonresponsive to conventional therapy.
Tanshinone IIA activates nuclear factor-erythroid 2-related factor 2 to restrain pulmonary fibrosis via regulation of redox homeostasis and glutaminolysis
Pulmonary fibrosis (PF) is characterized by myofibroblast activation through oxidative stress. However, the precise regulation of myofibroblast transdifferentiation remain largely uncharacterized.
Beneficial effects of oltipraz, nuclear factor - erythroid - 2 - related factor 2 (Nrf2), on renal damage in unilateral ureteral obstruction rat model
We investigated whether Oltipraz (OPZ) attenuated renal fibrosis in a unilateral ureteral obstruction (UUO) rat model.
Polysaccharide FMP-1 from Morchella esculenta attenuates cellular oxidative damage in human alveolar epithelial A549 cells through PI3K/AKT/Nrf2/HO-1 pathway
Oxidative stress is considered to involve cell death in severe pulmonary diseases like idiopathic pulmonary fibrosis (IPF). Polysaccharide FMP-1 from Morchella esculenta can exert significant antioxidant activity. However, its effects on alveolar epithelial cells remain unperceived. Herein, the effects of FMP-1 against HO-induced oxidative damage in human alveolar epithelial A549 cells were investigated. FMP-1 could inhibit HO-induced cytochrome C and Caspase-3 release to prevent cell apoptosis via attenuation of MDA and ROS levels, and enhancement the enzymatic activities of SOD and T-AOC. Furthermore, the underlying molecular mechanisms were clarified. The phosphorylation of AKT and the nuclear translocation of Nrf2 were observed to be promoted by FMP-1 as well as the level of HO-1. These findings suggested that FMP-1 attenuate cellular oxidative stress through PI3K/AKT pathway, and FMP-1 could be explored as natural potential antioxidants to lower oxidative stress relevant to the progression of IPF.
Uremia induces upregulation of cerebral tissue oxidative/inflammatory cascade, down-regulation of Nrf2 pathway and disruption of blood brain barrier
Chronic kidney disease (CKD) results in various central nervous systems (CNS) disorders including cognitive dysfunction, depression, anxiety, movement disorders, seizures and encephalopathy. Uremic retention products, oxidative stress, inflammation and impaired blood-brain barrier have been implicated as the major mediators of CKD-induced CNS disorders. However, mechanisms of CKD-induced cerebral tissue oxidative stress, inflammation and impaired blood brain barrier have not been fully elucidated and were explored. Male Sprague Dawley rats underwent sham operation or 5/6 nephrectomy and were observed for 10 weeks. Arterial pressure, body weight, and renal function were monitored. Under general anesthesia the animals' cerebral cortex was harvested. Nuclear translocations of NF-κB and Nrf2 and their key target gene products, neuronal, endothelial and inducible NO synthase (NOS) isoforms, markers of oxidative, nitrosative and myeloperoxidase reactions, fibrosis mediators and key protein constituents of capillary endothelial junctional complex were determined by Western blot analysis. The CKD rats exhibited reduced body weight, hypertension, elevated serum urea and creatinine concentrations. Compared to control group cerebral cortex of the CKD group showed activation (increased nuclear translocation) of NF-κB, elevation of pro-oxidant and pro-inflammatory molecules, diminished nuclear translocation of Nrf2 and expression of cytoprotective antioxidant molecules and depletion of the key protein constituents of endothelial junctional complex. In conclusion CKD results in the cerebral tissue activation of inflammatory and oxidative pathways, inhibition of antioxidant and cytoprotective system and erosion of cerebral capillary junctional complex, events that contribute to CNS dysfunction and impaired blood brain barrier.
Exogenous Pancreatic Kallikrein Improves Diabetic Cardiomyopathy in Streptozotocin-Induced Diabetes
To evaluate the protective effects of exogenous pancreatic kallikrein (PKK) treatment on diabetic cardiomyopathy (DCM) and explore the underlying mechanisms. Streptozotocin (STZ)-induced diabetic rats, a type 1 diabetic model, were treated with either PKK or saline for 12 weeks. Non-diabetic rats were used as controls. PKK administration attenuated the mitochondria swelling, Z line misalignments, myofibrosis and interstitial collagen accumulation in diabetic myocardial tissue. The oxidative stress imbalance including increased nitrotyrosine, decreased anti-oxidative components such as nuclear receptor nuclear factor like 2 (Nrf2), glutathione peroxidase 1(GPx-1), catalase (CAT) and superoxide dismutase (SOD), were recovered in the heart of PKK-treated diabetic rats. In diabetic rats, protein expression of TGF-β1 and accumulation of collagen I in the heart tissues was decreased after PKK administration. Markers for inflammation were decreased in diabetic rats by PKK treatment. Compared to diabetic rats, PKK reversed the degradation of IκB-α, an inhibitive element of heterotrimer nuclear factor kappa B (NF-κB). The endothelial nitric oxide synthase (eNOS) protein and myocardial nitrate/nitrite were impaired in the heart of diabetic rats, which, however, were restored after PKK treatment. The sarcoplasmic reticulum Ca-ATPase 2 (SERCA2) and phospholamban (PLN) were mishandled in diabetic rats, while were rectified in PKK-treated diabetic rats. The plasma NT-proBNP level was increased in diabetic rats while was reduced with PKK treatment. PKK protects against DCM via reducing fibrosis, inflammation, and oxidative stress, promoting nitric oxide production, as well as restoring the function of the calcium channel.
The -Antioxidant Response Element Signaling Pathway Controls Fibrosis and Autoimmunity in Scleroderma
Systemic sclerosis (SSc) is an autoimmune disease with fibrosis of the skin and internal organs and vascular alterations. Dysregulations in the oxidant/antioxidant balance are known to be a major factor in the pathogenesis of the disease. Indeed, reactive oxygen species (ROS) trigger neoepitopes leading to a breach of immune tolerance and autoimmune responses, activate fibroblasts to proliferate and to produce excess of type I collagen. ROS also alter endothelial cells leading to vascular dysfunction. Glutathione (GSH) is the most potent antioxidant system in eukaryotic cells. Numerous studies have reported a defect in GSH in SSc animal models and humans, but the origin of this defect remains unknown. The transcription factor NRF2 is a key player in the antioxidant defense, as it can induce the transcription of antioxidant and cytoprotective genes, including GSH, through its interaction with the antioxidant response elements. In this work, we investigated whether NRF2 could be implicated in the pathogenesis of SSc, and if this pathway could represent a new therapeutic target in this orphan disease with no curative medicine. Skin biopsies from 11 patients and 10 controls were harvested, and skin fibroblasts were extracted. Experimental SSc was induced both in BALB/c and in mice by daily intradermal injections of hypochloric acid. In addition, diseased BALB/c mice were treated with an agonist, dimethyl fumarate, or placebo. A drop in and target genes mRNA levels was observed in skin fibroblasts of SSc patients compared to controls. Moreover, the pathway is also downregulated in skins and lungs of SSc mice. In addition, we observed that mice have a more severe form of SSc with increased fibrosis and inflammation compared to wild-type SSc mice. Diseased mice treated with the agonist dimethyl fumarate (DMF) exhibited reduced fibrosis and immune activation compared to untreated mice. The treatment of skin fibroblasts from SSc mice with DMF restores GSH intracellular content, decreases ROS production and cell proliferation. These results suggest that the pathway is highly dysregulated in human and SSc mice with deleterious consequences on fibrosis and inflammation and that Nrf2 modulation represents a therapeutic target in SSc.