Eriodictyol-7-O-glucoside activates Nrf2 and protects against cerebral ischemic injury

Stroke is a complex disease that may involve oxidative stress-related pathways in its pathogenesis. The nuclear factor erythroid-2-related factor 2/antioxidant response element (Nrf2/ARE) pathway plays an important role in inducing phase II detoxifying enzymes and antioxidant proteins and thus has been considered a potential target for neuroprotection in stroke. The aim of the present study was to determine whether eriodictyol-7-O-glucoside (E7G), a novel Nrf2 activator, can protect against cerebral ischemic injury and to understand the role of the Nrf2/ARE pathway in neuroprotection. In primary cultured astrocytes, E7G increased the nuclear localization of Nrf2 and induced the expression of the Nrf2/ARE-dependent genes. Exposure of astrocytes to E7G provided protection against oxygen and glucose deprivation (OGD)-induced oxidative insult. The protective effect of E7G was abolished by RNA interference-mediated knockdown of Nrf2 expression. In vivo administration of E7G in a rat model of focal cerebral ischemia significantly reduced the amount of brain damage and ameliorated neurological deficits. These data demonstrate that activation of Nrf2/ARE signaling by E7G is directly associated with its neuroprotection against oxidative stress-induced ischemic injury and suggest that targeting the Nrf2/ARE pathway may be a promising approach for therapeutic intervention in stroke.     

Protective effect of fucoidan against acetaminophen-induced liver injury

Fucoidan, a sulfated polysaccharide extracted from various brown seaweeds, possesses a wide range of pharmacological properties. In this study, we investigated the protective effect of fucoidan on acetaminophen-induced acute liver injury in rats. Liver injury was induced by administration of acetaminophen (800 mg/kg, i.p.) and fucoidan was administered (100 mg kg, p.o.) 2 h before and after acetaminophen administration. After 24 h, co-treatment of fucoidan ameliorated liver damage and cell death induced by acetaminophen. Acetaminophen induced the overexpression of CYP2E1, one of the metabolizing enzymes of acetaminophen, but cotreatment with fucoidan suppressed its increased expression of CYP2E1. Fucoidan also reduced the hepatic apoptosis induced by acetaminophen exposure as shown in the protein expression of Bax, Bcl-2, and cleaved caspase-3. The anti-oxidative effect of fucoidan was observed from the increase of the production and expression of glutathione, superoxide dismutase, and glutathione peroxidase, both of which were decreased by acetaminophen. Also, fucoidan decreased the expression of inflammatory mediators, including tumor necrosis factoralpha, interleukin 1 beta, and inducible nitric oxide synthase. Taken together, the data demonstrate the hepato-protective effects of fucoidan against acetaminophen-induced liver injury via anti-oxidant, anti-inflammatory, and anti-apoptotic mechanisms.     

Protective effects of nicotinamide against acetaminophen-induced acute liver injury

Nicotinamide (NAM), the amide form of vitamin B3, is involved in a wide range of biological processes. Recent evidence revealed the anti-inflammatory and anti-oxidant properties of NAM and suggests it may be used as a novel strategy in the prevention of acute liver injury. In the present study, we investigated the potential protective effects of NAM on acetaminophen (APAP)-induced acute liver injury in mice. Mice were treated with NAM at 400 mg/kg 30 min before or after administration of APAP at a hepatotoxic dose of 400 mg/kg body weight via intraperitoneal injection. Liver injury and the expression of inflammation-related molecules were determined by histological examination and biochemical analysis, respectively. In addition, the survival rate of mice was assessed after APAP administration. Pretreatment with NAM for 30 min significantly decreased plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and malondialdehyde (MDA), and diminished histopathologic evidence of hepatic toxicity in mice following APAP administration. Similarly, posttreatment with NAM also decreased plasma ALT and AST levels in APAP-administrated mice. Furthermore, both pretreatment and posttreatment with NAM prolonged the survival rate of acute liver injury mice, accompanied by a significant reduction in the plasma levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), and interleukin-6 (IL-6). Together, these findings suggest that NAM possesses protective effects on APAP-induced liver injury, which may involve the anti-inflammatory action.     

Nrf2 protects against 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced oxidative injury and steatohepatitis

Previous studies demonstrate that Nrf2, a master regulator of antioxidative responses, is essential in mediating induction of many antioxidative enzymes by acute activation of the AhR. However, the role of Nrf2 in protecting against oxidative stress and DNA damage induced by sustained activation of the AhR remains unknown and was investigated herein. Tissue and blood samples were collected from wild-type (WT) and Nrf2-null mice 21 days after administration of a low-toxic dose (10 μg/kg ip) of TCDD. Only Nrf2-null mice lost body weight after TCDD treatment; however, blood levels of ALT were not markedly changed in either genotype, indicating a lack of extensive necrosis. Compared to livers of TCDD-treated WT mice, livers of TCDD-treated Nrf2-null mice had: 1) degenerated hepatocytes, lobular inflammation, marked fat accumulation, and higher mRNA expression of inflammatory and fibrotic genes; 2) depletion of glutathione, elevation in lipid peroxidation and marker of DNA damage; 3) attenuated induction of phase-II enzymes Nqo1, Gsta1/2, and Ugt2b35 mRNAs, but higher induction of cytoprotective Ho-1, Prdx1, Trxr1, Gclc, and Epxh1 mRNAs; 4) higher mRNA expression of Fgf21 and triglyceride-synthesis genes, but down-regulation of bile-acid-synthesis genes and cholesterol-efflux transporters; and 5) trend of induction/activation of c-jun and NF-kB. Additionally, TCDD-treated Nrf2-null mice had impaired adipogenesis in white adipose tissue. In conclusion, Nrf2 protects livers of mice against oxidative stress, DNA damage, and steatohepatitis induced by TCDD-mediated sustained activation of the AhR. The aggravated hepatosteatosis in TCDD-treated Nrf2-null mice is due to increased lipogenesis in liver and impaired lipogenesis in white adipose tissue.     

Simvastatin protects against cholestasis-induced liver injury

Background:

Bile duct obstruction is associated with hepatic accumulation of leukocytes and liver injury. The aim of this study was to evaluate the effect of simvastatin on cholestasis-induced liver inflammation and tissue damage.

Experimental approach:

C57BL/6 mice were treated with simvastatin (0.02 and 0.2 mg·kg⁻¹) and vehicle before and after undergoing bile duct ligation (BDL) for 12 h. Leukocyte recruitment and microvascular perfusion in the liver were analysed using intravital fluorescence microscopy. CXC chemokines in the liver were determined by enzyme-linked immunosorbent assay. Liver damage was monitored by measuring serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Hepatic levels of myeloperoxidase (MPO) were also determined.

Key results:

Administration of 0.2 mg·kg⁻¹ simvastatin decreased ALT and AST by 87% and 83%, respectively, in BDL mice. This dose of simvastatin reduced hepatic formation of CXC chemokines by 37–82% and restored sinusoidal perfusion in cholestatic animals. Moreover, BDL-induced leukocyte adhesion in sinusoids and postsinusoidal venules, as well as MPO levels in the liver, was significantly reduced by simvastatin. Notably, administration of 0.2 mg·kg⁻¹ simvastatin 2 h after BDL induction also decreased cholestatic liver injury and inflammation.

Conclusions and implications:

These findings show that simvastatin protects against BDL-induced liver injury. The hepatoprotective effect of simvastatin is mediated, at least in part, by reduced formation of CXC chemokines and leukocyte recruitment. Thus, our novel data suggest that the use of statins may be an effective strategy to protect against the hepatic injury associated with obstructive jaundice.     

Cannabinoid-2 receptor activation protects against infarct and ischemia-reperfusion heart injury

Endocannabinoid system is reported to be activated during myocardial ischemia-reperfusion (IR) injury and protects against heart injury. We, therefore, observed changes in endocannabinoids levels during acute myocardial infarction (AMI) and myocardial IR injury and evaluated the role of cannabinoid-2 (CB2) receptor in infarct and IR heart injury. In contrast to 16 control patients with normal coronary artery angiogram, the endocannabinoid 2-arachidonoylglycerol level in the infarct-side coronary artery of 23 AMI patients increased significantly, with increased reactive oxygen species and tumor necrosis factor-α levels in both infarct-side coronary artery and radial artery. Then, 35 C57BL/6J mice were made into SHAM, AMI, or IR models. AMI and IR groups were treated with CB2-selective agonist HU308 ((+)-(1aH,3H,5aH)-4-[2,6-dimethoxy-4-(1,1-dimethylheptyl)phenyl]-6,6-dimethylbicyclo[3.1.1]hept-2-ene-2-carbinol), with or without CB2-selective antagonist AM630 [6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indol-3-yl](4-methoxyphenyl)methanone through intraperitoneal injection. Compared with the SHAM, expressions of cannabinoid CB1/CB2 receptor proteins in AMI/IR animals were upregulated; production of 2-arachidonoylglycerol and anandamide and release of reactive oxygen species and tumor necrosis factor-α also increased. HU308 significantly decreased the infarct size and the levels of reactive oxygen species and tumor necrosis factor-α in AMI/IR animals. However, these effects were blocked by AM630. In conclusion, the endocannabinoid system was activated during AMI and IR, and CB2 receptor activation produces a protective role, thus offering a novel pharmaceutical target for treating these diseases.     

Protection of Flos Lonicerae against acetaminophen-induced liver injury and its mechanism

This study aims to observe the protective action of Flos Lonicerae (FL) aqueous extract against acetaminophen (AP)-induced liver injury and its mechanism. Results show that FL decreases AP-increased serum alanine/aspartate transaminases (ALT/AST) activity, as well as total bilirubin (TB) amount, in mice. Histological evaluation of the liver further confirms the protection of FL against AP-induced hepatotoxicity. TdT-mediated biotin-dUTP nick-end labeling (TUNEL) assay shows that FL reduces AP-increased apoptotic cells. Furthermore, AP-decreased liver glutamate-cysteine ligase (GCL) enzymatic activity and glutathione (GSH) amount are both reversed by FL because of the increased expression of the catalytic subunit of GCL (GCLC) protein. The amount of chlorogenic acid (CGA), caffeic acid, and luteolin, the main active compounds in FL, is detected by high-performance liquid chromatography (HPLC). In addition, cell viability assay demonstrates that polyphenols in FL, such as CGA, caffeic acid, as well as isochlorogenic acids A, B, and C, can reverse AP-induced cytotoxicity. In conclusion, FL can prevent AP-induced liver injury by inhibiting apoptosis. The cellular antioxidant enzyme GCL is also involved in such protection. Polyphenols may be the main active hepato-protective ingredients in FL.     

Sulforaphane protects kidneys against ischemia-reperfusion injury through induction of the Nrf2-dependent phase 2 enzyme

Reactive oxygen species are important mediators that exert a toxic effect during ischemia-reperfusion injury of various organs. Sulforaphane, which is a naturally occurring isothiocyanate that is present in cruciferous vegetables such as broccoli, is known to be an indirect antioxidant that acts by inducing Nrf2-dependent phase 2 enzymes. Phase 2 enzymes such as heme oxygenase-1, NAD(P)H: quinone oxidoreductase 1, glutathione reductase, and glutathione peroxidase participate in adaptive and protective responses to oxidative stress and various inflammatory stimuli. Therefore, we evaluated the preactivation of Nrf2 by sulforaphane to determine if it could inhibit ischemia-reperfusion-induced kidney damage. Treatment of HK2 renal tubular epithelial cells with sulforaphane effectively protected cells against cytotoxicity induced by hypoxia-reoxygenation, and sulforaphane dramatically induced phase 2 enzymes by decreasing the Keap1 protein levels and increasing Nrf2 nuclear translocation. Additionally, a second set of experiments using a renal ischemia-reperfusion model produced results that were essentially the same as those observed when HK2 cells were used; namely, that sulforaphane induced Nrf2-dependent phase 2 enzymes and thereby improved ischemia-reperfusion-induced changes in the lipid hydroperoxides, glutathione, creatinine clearance, kidney weight, and histologic abnormalities. Collectively, these results suggest that sulforaphane can be used as an effective adjunct for the prevention of renal oxidative insults during ischemia-reperfusion injury.     

Rhein protects against acetaminophen-induced hepatic and renal toxicity

This study investigated the possible protective effects and mechanism of rhein on Acetaminophen (APAP)-induced hepatotoxicity and nephrotoxicity in rats. Treatment of rats with APAP resulted in severe liver and kidney injuries, as demonstrated by drastic elevation of serum glutamate-pyruvate transaminase (GPT), glutamate-oxaloacetic transaminase (GOT), total bilirubin (TBIL), creatinine (CREA), urea nitrogen (UREA) levels and typical histopathological changes including necrosis, phlogocyte infiltration and fatty degeneration in liver, tubules epithelium swelling and severe vacuolar degeneration in kidney. APAP caused oxidative stress, as evidenced by increased reactive oxygen species (ROS) production, nitric oxide (NO) and malondiadehyde (MDA) levels, together with depleted glutathione (GSH) concentration in the liver and kidney of rats. However, rhein can attenuate APAP-induced hepatotoxicity and nephrotoxicity in a dose-dependent manner. Our results showed that GPT, GOT, UREA and CREA levels and ROS production were reduced dramatically, NO, MDA, GSH contents were restored remarkedly by rhein administration, as compared to the APAP alone treated rats. Moreover, the histopathological damage of liver and kidney were also significantly ameliorated by rhein treatment. These findings suggested that the protective effects of rhein against APAP-induced liver and kidney injuries might result from the amelioration of APAP-induced oxidative stress.     

Samarcandin protects against testicular ischemia/reperfusion injury in rats via activation of Nrf2/HO-1-mediated antioxidant responses

The purpose of this study was to evaluate the effectiveness of samarcandin (SMR) in preventing testicular injury caused by ischemia/reperfusion (I/R) in rats. Rats were divided into 4 groups at random: the sham group, the T/D control group (CONT), the T/D group receiving SMR treatment at 10 mg/kg (SMR-10), and the T/D group receiving SMR treatment at 20 mg/kg (SMR-20). When compared to the CONT group, SMR improved the oxidant/antioxidant balance by reducing malondialdehyde (MDA), nitric oxide (NOx), and increasing reduced glutathione (GSH), gluta-thione peroxide (GSH-Px), and superoxide dismutase (SOD). Moreover, SMR increased the levels of the steroid hormones’ testosterone (TST), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) in the blood as well as controlled the inflammatory mediators; interleukin-6 (IL6), tumor necrosis factor alpha (TNF-α), and nuclear factor κB (NF-κB). Nevertheless, SMR-treated animals showed a considerable downregulation of the apoptotic marker caspase-3. The T/D-induced histopathological changes were reduced and Proliferating Cell Nuclear Antigen (PCNA) protein expression was enhanced by SMR. These effects are associated with upregulation of testicular (Nuclear factor erythroid 2-related factor 2 (Nrf2), Heme oxygenase-1 (HO-1), and downregulation of NF-κB mRNA expression levels. These findings suggest that SMR may be able to prevent T/D-induced testis damage by mainly regulating the expression of Nrf2 and NF-B, which seems to mediate its promising antioxidant, anti-inflammatory and antiapoptotic effects seen in this study.     

Genistein protection against acetaminophen-induced liver injury via its potential impact on the activation of UDP-glucuronosyltransferase and antioxidant enzymes

The purpose of this study was to investigate genistein’s influence on the relationship between the activation of uridine diphosphate glucuronosyltransferase (UGTs) and the protection against acetaminophen-induced liver toxicity. Animal experimental results revealed that genistein (50, 100 or 200 mg/BWkg) significantly ameliorated the biomarkers alanine aminotransferase, alanine aminotransferase, lactate dehydrogenase and malondialdehyde, as indicators of acute liver damage caused by APAP (200 mg/BWkg). The level of GSH declined sharply after treatment with APAP within 1 h in both the liver and blood with and without genistein. However, after 16 h, the levels approached or returned to the original level. Genistein may accelerate and promote APAP glucuronidation as the results showed that APAP-glucuronide increased by 18.44%, 46.79%, and 66.49% for 4 h of treatment with genistein dosages of 50, 100 or 200 mg/BWkg, respectively, compared with the APAP-only treatment. The activation of UGTs and glutathione peroxidase and the inhibition of CYP2E1 by genistein were observed, and UGTs mRNA expression level with genistein was measured. These findings suggest that genistein can prevent and protect against APAP-induced liver toxicity due to the inhibition of APAP biotransformation and the resistance to oxidative stress via the modulation of the activities of metabolism and the antioxidant enzyme.     

The E3 ubiquitin ligase NEDD4-1 protects against acetaminophen-induced liver injury by targeting VDAC1 for degradation

Acetaminophen (APAP) overdose is a major cause of liver injury. Neural precursor cell expressed developmentally downregulated 4–1 (NEDD4-1) is an E3 ubiquitin ligase that has been implicated in the pathogenesis of numerous liver diseases; however, its role in APAP-induced liver injury (AILI) is unclear. Thus, this study aimed to investigate the role of NEDD4-1 in the pathogenesis of AILI. We found that NEDD4-1 was dramatically downregulated in response to APAP treatment in mouse livers and isolated mouse hepatocytes. Hepatocyte-specific NEDD4-1 knockout exacerbated APAP-induced mitochondrial damage and the resultant hepatocyte necrosis and liver injury, while hepatocyte-specific NEDD4-1 overexpression mitigated these pathological events both in vivo and in vitro. Additionally, hepatocyte NEDD4-1 deficiency led to marked accumulation of voltage-dependent anion channel 1 (VDAC1) and increased VDAC1 oligomerization. Furthermore, VDAC1 knockdown alleviated AILI and weakened the exacerbation of AILI caused by hepatocyte NEDD4-1 deficiency. Mechanistically, NEDD4-1 was found to interact with the PPTY motif of VDAC1 through its WW domain and regulate K48-linked ubiquitination and degradation of VDAC1. Our present study indicates that NEDD4-1 is a suppressor of AILI and functions by regulating the degradation of VDAC1.     

Cholecystokinin protects mouse liver against ischemia and reperfusion injury

BackgroundCholecystokinin (CCK), as a gastrointestinal hormone, has an important protective role against sepsis or LPS-induced endotoxic shock. We aim to address the role of CCK in hepatic ischemia followed by reperfusion (I/R) injury.Materials and methodsA murine model of 60 min partial hepatic ischemia followed by 6 h of reperfusion was used in this study. CCK and CCKAR Levels in blood and liver were detected at 3 h, 6 h, 12 h and 24 h after reperfusion. Then the mice were treated with CCK or proglumide, a nonspecific CCK-receptor (CCK-R) antagonist. Mice were randomly divided into four groups as follows: (1) sham group, in which mice underwent sham operation and received saline; (2) I/R group, in which mice were subjected to hepatic I/R and received saline; (3) CCK group, in which mice were subjected to hepatic I/R and treated with CCK (400 μg/kg); (4) proglumide group (Pro), in which mice underwent hepatic I/R and treated with proglumide (3 mg/kg); CCK and proglumide were administrated via tail vein at the moment of reperfusion. Serum AST (sAST) and serum ALT (sALT) were determined with a biochemical assay and histological analysis were performed with hematoxylin-eosin (H&E). Cytokines (IL-1β, IL-6, IL-10, TNF-α) expressions in blood were determined with enzyme-linked immunosorbent assay (ELISA). The MPO (myeloperoxidase) assay were used to measure neutrophils' infiltration into the liver. The apoptotic index (TUNEL-positive cell number / total liver cell number × 100%) was calculated to assess hepatocelluar apoptosis. Finally, activation of NF-κB and phosphor-p38 expression in liver homogenates were analyzed with Western Blot (WB).ResultsOur findings showed that 1) CCK and CCK-AR were upregulated in our experimental model over time; 2) Treatment with CCK decreased sAST/sALT levels, inflammatory hepatic injury, neutrophil influx and hepatocelluar apoptosis, while proglumide aggravated hepatic injury.ConclusionThese findings support our hypothesis and suggest that CCK played a positive role in the ongoing inflammatory process leading to liver I/R injury.     

Biochanin A protects lipopolysaccharide/D-galactosamine-induced acute liver injury in mice by activating the Nrf2 pathway and inhibiting NLRP3 inflammasome activation

Biochanin A, an isoflavone existed in red clover and peanuts, has been reported to possess a wide spectrum of pharmacological activities, such as anti-inflammatory and antioxidant effects. However, the protective effects and mechanism of biochanin A on liver injury have not been reported. In this study, acute liver injury was induced by intraperitoneal injection of lipopolysaccharide (LPS) and d-galactosamine (D-GalN). Biochanin A was administrated 1 h prior to LPS/D-GalN challenge. Serum ALT, AST, IL-1β, and TNF-α levels, hepatic malondialdehyde (MDA), GPx, SOD, and Catalase contents, tissue histology, IL-1β, TNF-α, NLRP3, and Nrf2 expression were detected. The results showed that serum ALT, AST, IL-1β, and TNF-α levels and hepatic MDA content increased after LPS/GalN treatment. These changes were attenuated by biochanin A. Meanwhile, biochanin A dose-dependently up-regulated the expression of Nrf2 and HO-1. Biochanin A also inhibited hepatic IL-1β and TNF-α expression in a dose-dependent manner. Biochanin A did not inhibit LPS/D-GalN-induced hepatic NLRP3, ASC, and caspase-1 expression. However, the interaction of NLRP3 with ASC and caspase-1 were inhibited by biochanin A. In addition, LPS/D-GalN-induced up-regulation of thioredoxin-interacting protein (TXNIP) and interaction between TXNIP and NLRP3 were also inhibited by biochanin A. In conclusion, biochanin A protected against LPS/GalN-induced liver injury by activating the Nrf2 pathway and inhibiting NLRP3 inflammasome activation.     

基于代谢组学研究二苯乙烯苷在对乙酰氨基酚诱导小鼠肝损伤中的保护作用

目的:通过非靶向代谢组学等研究方法探讨二苯乙烯苷(tetrahydroxy stilbene glucoside,TSG)对乙酰氨基酚(acetaminophen,APAP)造成急性肝损伤的保护作用。方法:采用随机分组方式将SPF级C57BL/6小鼠分为APAP模型组和TSG干预组,每组15只。灌胃给予小鼠TSG连续7 d后,一次性腹腔注射APAP进行造模,6 h后取肝脏组织。结果:H&E染色、MDA和SOD检测表明单次APAP注射会造成肝脏损伤,TSG干预会降低肝脏受损程度。代谢产物检测结果显示,与APAP模型组相比,TSG组的ABC转运体、胆碱代谢、中心碳代谢、半乳糖、丙氨酸类氨基酸代谢等变化显著。结论:TSG通过改善脂质过氧化和能量代谢紊乱等过程抵御APAP导致的急性肝损伤。     

Ethyl ferulate protects against lipopolysaccharide-induced acute lung injury by activating AMPK/Nrf2 signaling pathway

Ethyl ferulate (EF) is abundant in Rhizoma Chuanxiong and grains (e.g.,rice and maize) and possesses antioxidative,antiapoptotic,antirheumatic,and anti-inflamma...