Upregulation of Sirt1 in carbon-tetrachloride–induced acute liver injury

18β-Glycyrrhetinic Acid Protects against Cholestatic Liver Injury in Bile Duct-Ligated Rats

18β-Glycyrrhetinic acid is a nutraceutical agent with promising hepatoprotective effects. Its protective mechanisms against cholestatic liver injury were further investigated in a rodent model of extrahepatic cholestasis caused by Bile Duct Ligation (BDL) in rats. The daily oral administration of 18β-Glycyrrhetinic acid improved liver histology, serum biochemicals, ductular reaction, oxidative stress, inflammation, apoptosis, impaired autophagy, and fibrosis. 18β-Glycyrrhetinic acid alleviated the BDL-induced hepatic and systemic retention of bile acids, matrix-producing cell activation, hepatic collagen deposition, Transforming Growth Factor beta-1/Smad activation, malondialdehyde elevation, glutathione reduction, High Mobility Group Box-1/Toll-Like Receptor-4 activation, NF-κB activation, inflammatory cell infiltration/accumulation, Interleukin-1β expression, Signal Transducer and Activator of Transcription-1 activation, Endoplasmic Reticulum stress, impairment autophagy, and caspase 3 activation. Conversely, the protein expression of Sirt1, Farnesoid X Receptor, nuclear NF-E2-Related Factor-2, Transcription Factor EB, bile acid efflux transporters, and LC3-II, as well as the protein phosphorylation of AMP-Activated Protein Kinase, was promoted in 18β-Glycyrrhetinic acid-treated BDL rats. The hepatoprotective effects of 18β-Glycyrrhetinic acid in the present investigation correlated well with co-activation and possible interactions among Sirt, FXR, and Nrf2. The concurrent or concomitant activation of Sirt1, FXR, and Nrf2 not only restored the homeostatic regulation of bile acid metabolism, but also alleviated oxidative stress, inflammation, apoptosis, impaired autophagy, and fibrosis.

Potential Effects of Dietary Isoflavones on Drug-Induced Liver Injury

Numerous prescribed drugs and herbal and dietary supplements have been reported to cause drug-induced acute liver injury, which is a frequent cause of acute liver failure (ALF). It is a tremendous challenge with ever-increasing drug application in the medication system for huge populations. Drug-induced acute liver injury can lead to diverse pathologies similar to acute and chronic hepatitis, acute liver failure, biliary obstruction, fatty liver disease, and so on. Recently, extensive work demonstrated that isoflavones play an essential and protecting role in drug-induced liver injury (DILI). The isoflavones mediated hepatoprotection by modulating specific genes linked with control of cellular redox homeostasis and inflammatory responses. Isoflavones upregulate oxidative stress-responsive nuclear factor erythroid 2-like 2 (Nrf2), downregulate inflammatory nuclear factor-κB (NF-κB) signaling pathways, and modulate a balance between cell survival and death. Moreover, isoflavones actively inhibit the expression of cytochromes P450 (CYPs) enzyme during drug metabolism. Moreover, isoflavones are also linked with farnesoid X receptor (FXR) activation and signal transducer and activator of transcription factor 3 (STAT3) phosphorylation in hepatoprotection DILI. In vivo and in vitro studies clearly stated that isoflavones bear strong antioxidant potential and promising agents for hepatotoxicity prevention and stressed their potential role as therapeutic supplements in DILI. The current review will elaborate on isoflavones’ preventive and therapeutic potential concisely and highlight various molecular targets to exert a protective effect on DILI.

Naringenin protects RPE cells from NaIO3-induced oxidative damage in vivo and in vitro through up-regulation of SIRT1

BACKGROUND

Dry age-related macular degeneration (dAMD) leads to serious burden of visual impairment and there is no definitive treatment. Previous studies have showed that naringenin (NAR) significantly increased electroretinography (ERG) c-wave in sodium iodate (NaIO₃)-treated rats and viability of NaIO₃-treated ARPE-19 cells. But the underlying mechanism is still unknown.

PURPOSE

We tested the hypothesis that anti-oxidation mediated by Sirtuin 1 (SIRT1) was important to the protective effect of NAR on dAMD.

STUDY DESIGN/METHODS

NaIO₃-induced mice retinopathy and ARPE-19 cells injury models were established. In vivo, the protective effect of NAR eye drops on retina was evaluated by flash ERG (FERG) recording and histopathological examination. In vitro, viability of ARPE-19 cells, and the levels of lactic dehydrogenase (LDH), reactive oxygen species (ROS) and carbonyl protein were detected. Protein expression of SIRT1 was analyzed by immunochemical staining, immunofluorescence and western blotting.

RESULTS

NAR eye drops improved retinal function and morphology and normalized the protein expression of SIRT1 in mice exposed to NaIO₃. NAR promoted the survival of ARPE-19 cells in a concentration-dependent manner. NAR up-regulated SIRT1 protein expression, and decreased levels of ROS and carbonyl protein. Moreover, EX527, a selective inhibitor of SIRT1, abolished the effects of NAR on the cell viability and ROS. In addition, SRT1720, a selective agonist of SIRT1, improved the viability of cells and suppressed the production of ROS.

CONCLUSION

Our findings indicate that SIRT1-mediated anti-oxidation contributes to the protective effect of NAR eye drops on dAMD.

Ameliorative Effect of Graviola (Annona muricata) on Mono Sodium Glutamate-Induced Hepatic Injury in Rats: Antioxidant, Apoptotic, Anti-inflammatory, Lipogenesis Markers, and Histopathological Studies

Simple Summary

Food additives, especially monosodium glutamate (MSG), induces serious liver disorders. This study premeditated to investigate the effect of Graviola extract (GE) on hepatic and cellular alterations induced by MSG. Our result revealed that GE administration normalized the oxidative stress markers, as well as the proinflammatory cytokines, in addition to downregulation of the inducible nitric oxide synthase (iNOS) and FAS, hepatic fatty acid synthase, and led to the upregulation of the silent information regulator protein one (SIRT1) gene. This is the first report investigating the intracellular pathway and mechanism of Graviola extract’s action in alleviating the MSG supplementation injuries.

Abstract

Monosodium glutamate (MSG) is a widely used food additive, and there is a trepidation that MSG plays a critical role in multiple hepatic disorders. This study was planned to investigate Graviola extract (GE) effects on hepatic and cellular alterations induced by MSG. Fifty Wistar rats were randomly allocated into five groups: control (received normal saline), Graviola (received 200 mg/kg body weight), MSG (received 2.4 gm MSG/kg, 15% of Lethal dose (LD₅₀) of MSG), Graviola + monosodium glutamate (MSG + GE; received GE, 200 mg/kg/day and MSG 2.4 gm/kg body weight (BW) for the next four weeks), and monosodium glutamate + Graviola (received MSG only (2.4 gm/kg BW) daily for four weeks, then concomitant with Graviola (200 mg/kg BW) daily for the next four weeks. MSG and GR were administered orally for eight weeks. Our results showed that MSG caused a significant increase in oxidative stress markers malondialdehyde (MDA), reactive oxygen species (ROS), nitric oxide (NO), hydrogen peroxide (H₂O₂), proinflammatory cytokines interleukin 6 (IL-6) level, a tumor protein (P53), hepatic cellular damage, as well as proapoptotic markers caspase-3, and B-cell lymphoma 2 (BCL-2)-like protein 4 (Bax). A significant decrease in superoxide dismutase (SOD), catalase (CAT), glutathione S transferase (GST), reduced glutathione (GSH), and an antiapoptotic agent B-cell lymphoma 2 (BCl-2) was observed. The detected MSG effects were normalized by Graviola administration, either a prophylactic or protecting dose. Besides, Graviola reduced the expression of inducible nitric oxide synthase (iNOS) and hepatic fatty acid synthase (FAS) and led to the upregulation of the silent information regulator protein one gene expression gene (SIRT1).In conclusion, the results suggest that Gaviola’s interrelated antiapoptotic, antioxidant, and anti-inflammatory properties are potential mechanisms to enhance hepatic deficits and protect the liver. Graviola can, therefore, be considered a promising hepatoprotective supplement. Additionally, further human clinical trials are also necessary to validate the present research.

Improved protective effects of American ginseng berry against acetaminophen-induced liver toxicity through TNF-α-mediated caspase-3/-8/-9 signaling pathways

BACKGROUND

Similar to the leaves of P. Quinquefolius, American ginseng berry (AGB) is another important part of P. Quinquefolius with alternative therapeutic potential. The liver protection capabilities of the former have been demonstrated previously, however, the later has not yet been evaluated.

PURPOSE

Based on our previous observation, the present work was designed to evaluate the hepatic protective effects for novel mechanisms of AGB in acetaminophen (APAP)-induced liver injury in vivo.

STUDY DESIGN/METHODS

All mice were divided into four groups as follows: normal group, APAP group and APAP + AGB (150 mg/kg and 300 mg/kg) groups. AGB were orally administered for one week before exposure to APAP (250 mg/kg). Severe liver injury was observed and hepatotoxicity was evaluated after 24 h through evaluating the biochemical markers, protein expressions levels and liver histopathology.

RESULTS

Our study results clearly demonstrated that AGB pretreatment ameliorated APAP-induced hepatic injury as evidenced by decreasing plasma alanine aminotransferase (ALT), aspartate transaminase (AST), tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) compared to the APAP group. Western blotting analysis showed that pretreatment with AGB decreased the expressions levels of TNF-α and nuclear transcription factor-κB (NF-κB p65) in liver tissues. Meanwhile, the protein expression levels of caspases, cytochrome c, and Bax were elevated by AGB treatment for seven days, while the protein expression level of Bcl-2 was inhibited comparison with that in APAP group. Furthermore, supplement of AGB resulted in increase of superoxide dismutase (SOD) and glutathione (GSH), while decrease of malondialdehyde (MDA) content and the expression levels of 4-hydroxynonenal (4-HNE) and cytochrome P450 E1 (CYP2E1). The results of histopathological staining demonstrated that AGB pretreatment inhibited APAP-induced hepatocyte infiltration, congestion, and necrosis.

CONCLUSION

The present study demonstrated that AGB pretreatment protected liver cells against APAP-induced hepatotoxicity through inhibition of oxidative stress, inflammation responses via TNF-α-mediated caspase-3/-8/-9 signaling pathways.

Hepatoprotective effect of grape seed oil against carbon tetrachloride induced oxidative stress in liver of γ-irradiated rat

Carbon tetrachloride (CCl4) and ionizing radiation are well known environmental pollutants that generate free radicals and induce oxidative stress. The liver is the primary and major target organ responsible for the metabolism of drugs, toxic chemicals and affected by irradiation. This study investigated the effect of grape seed oil (GSO) on acute liver injury induced by carbon tetrachloride (CCl4) in γ-irradiated rats (7Gy). CCl4-intoxicated rats exhibited an elevation of ALT, AST activities, IL-6 and TNF-α level in the serum. Further, the levels of MDA, NO, NF-κB and the gene expression of CYP2E1, iNOS and Caspase-3 were increased, and SOD, CAT, GSH-Px, GST activities and GSH content were decreased. Furthermore, silent information regulator protein 1 (SIRT1) gene expression was markedly down-regulated. Additionally, alterations of the trace elements; copper, manganese, zinc and DNA fragmentation was observed in the hepatic tissues of the intoxicated group. These effects were augmented in CCl4-intoxicated-γ-irradiated rats. However, the administration of GSO ameliorated these parameters. GSO exhibit protective effects on CCl4 induced acute liver injury in γ-irradiated rats that could be attributed to its potent antioxidant, anti-inflammatory and anti-apoptotic activities. The induction of the antioxidant enzymes activities, down-regulation of the CYP2E1, iNOS, Caspase-3 and NF-κB expression, up-regulation of the trace elements concentration levels and activation of SIRT1 gene expression are responsible for the improvement of the antioxidant and anti-inflammatory status in the hepatic tissues and could be claimed to be the hepatoprotective mechanism of GSO.