Erythritol Improves Nonalcoholic Fatty Liver Disease by Activating Nrf2 Antioxidant Capacity

Identification and evaluation of Pharmacological enhancers of the factor VII p.Q160R variant

Congenital factor (F) VII deficiency is caused by mutations in the F7 gene. The p.Q160R variant manifests with bleeding episodes due to reduced FVII activity and antigen in patient plasma, most likely caused by protein misfolding and intracellular retention. As current replacement therapy is expensive and requires frequent intravenous injections, there is an unmet need for new and less invasive therapeutic strategies. Drug repurposing allows for rapid, more cost-effective discovery and implementation of new treatments, and identification of pharmacological enhancers of FVII variant activity would be of clinical importance. High-throughput screening of > 1800 FDA-approved drugs identified the orally available histone deacetylase inhibitor abexinostat and the inhaled surfactant tyloxapol as enhancers of FVII p.Q160R variant activity. The positive hits were verified in an in vitro cell model transiently expressing wild type or variant FVII and ex vivo in patients' plasma. Both drugs showed a dose-response effect on FVII antigen and activity levels in conditioned cell medium and on FVII activity in patients' plasma. In conclusion, the efficacy of the FDA-approved drugs abexinostat and tyloxapol in enhancing FVII variant activity constitute a proof of principle for high-throughput identification of drugs that may be feasible for novel treatment of FVII deficiency.

Microenvironment-induced programmable nanotherapeutics restore mitochondrial dysfunction for the amelioration of non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a metabolic liver disorder with severe complications. Mitochondrial dysfunction due to over-opening of the mitochondrial permeability transition pore (mPTP) in liver cells plays a central role in the development and progression of NAFLD. Restoring mitochondrial function is a promising strategy for NAFLD therapy. Herein, we designed and developed a microenvironment-induced programmable nanotherapeutic to restore mitochondrial function and ameliorate NAFLD. cyclosporine (Cyclosporine capsules) A (CsA), as a highly effective inhibitors of the opening of mPTP, was chosen in the present work. Nanotherapeutics were prepared by assembling two structurally simple multifunctional glucosamine derivatives: dextran-grafted galactose (Dex-Gal) and Dex-triphenylphosphine (Dex-TPP). Galactose units in the nanotherapeutics guide the hepatocyte-specific uptake. Detachment of galactose from acidic lysosomes via Schiff base cleavage exposes the TPP moieties, which subsequently steers the nanotherapeutics to escape from lysosomes and target mitochondria through an enhanced positive charge, enabling precise in situ drug delivery. Simultaneously, the nanotherapeutics improved mitochondrial dysfunction by inhibiting palmitic acid-induced opening of the mitochondrial permeability transition pore in HepG2 cells, maintaining mitochondrial membrane potential, and decreasing reactive oxygen species production. Furthermore, CsA@Dex-Gal/TPP accumulated in the livers of NAFLD mice, restored mitochondrial autophagy, regulated abnormalities in glucose and lipid metabolism, and improved hepatic lipid deposition. This study offers a new cascading strategy for targeting liver cell mitochondria to treat NAFLD and other mitochondria-associated diseases. STATEMENT OF SIGNIFICANCE: We design microenvironment-induced programmable nanotherapeutics for NAFLD Nanotherapeutics has the capabilities of lysosomal escape and mitochondrial targeting Nanotherapeutics improves mitochondrial dysfunction and ameliorates NAFLD This study offers a new cascading strategy for other mitochondria-associated diseases.

Metabolic dysfunction-associated steatotic liver disease-induced changes in the antioxidant system: a review

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a heterogeneous condition characterized by liver steatosis, inflammation, consequent fibrosis, and cirrhosis. Chronic impairment of lipid metabolism is closely related to oxidative stress, leading to cellular lipotoxicity, mitochondrial dysfunction, and endoplasmic reticulum stress. The detrimental effect of oxidative stress is usually accompanied by changes in antioxidant defense mechanisms, with the alterations in antioxidant enzymes expression/activities during MASLD development and progression reported in many clinical and experimental studies. This review will provide a comprehensive overview of the present research on MASLD-induced changes in the catalytic activity and expression of the main antioxidant enzymes (superoxide dismutases, catalase, glutathione peroxidases, glutathione S-transferases, glutathione reductase, NAD(P)H:quinone oxidoreductase) and in the level of non-enzymatic antioxidant glutathione. Furthermore, an overview of the therapeutic effects of vitamin E on antioxidant enzymes during the progression of MASLD will be presented. Generally, at the beginning of MASLD development, the expression/activity of antioxidant enzymes usually increases to protect organisms against the increased production of reactive oxygen species. However, in advanced stage of MASLD, the expression/activity of several antioxidants generally decreases due to damage to hepatic and extrahepatic cells, which further exacerbates the damage. Although the results obtained in patients, in various experimental animal or cell models have been inconsistent, taken together the importance of antioxidant enzymes in MASLD development and progression has been clearly shown.

Establishment of a non-alcoholic fatty liver disease model by high fat diet in adult zebrafish

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in recent years, but the pathogenesis is not fully understood. Therefore, it is important to establish an effective animal model for studying NAFLD.

METHODS

Adult zebrafish were fed a normal diet or a high-fat diet combined with egg yolk powder for 30 days. Body mass index (BMI) was measured to determine overall obesity. Serum lipids were measured using triglyceride (TG) and total cholesterol (TC) kits. Liver lipid deposition was detected by Oil Red O staining. Liver injury was assessed by measuring glutathione aminotransferase (AST) and glutamic acid aminotransferase (ALT) levels. Reactive oxygen species (ROS) and malondialdehyde (MDA) were used to evaluate oxidative damage. The level of inflammation was assessed by qRT-PCR for pro-inflammatory factors. H&E staining was used for pathological histology. Caspase-3 immunofluorescence measured apoptosis. Physiological disruption was assessed via RNA-seq analysis of genes at the transcriptional level and validated by qRT-PCR.

RESULTS

The high-fat diet led to significant obesity in zebrafish, with elevated BMI, hepatic TC, and TG. Severe lipid deposition in the liver was observed by ORO and H&E staining, accompanied by massive steatosis and ballooning. Serum AST and ALT levels were elevated, and significant liver damage was observed. The antioxidant system in the body was severely imbalanced. Hepatocytes showed massive apoptosis. RNA-seq results indicated that several physiological processes, including endoplasmic reticulum stress, and glucolipid metabolism, were disrupted.

CONCLUSION

Additional feeding of egg yolk powder to adult zebrafish for 30 consecutive days can mimic the pathology of human nonalcoholic fatty liver disease.

Pueraria lobata antioxidant extract ameliorates non-alcoholic fatty liver by altering hepatic fat accumulation and oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Pueraria lobata is essential medicinal and edible homologous plants widely cultivated in Asian countries. Therefore, P. lobata is widely used in the food, health products and pharmaceutical industries and have significant domestic and international market potential and research value. P. lobata has remarkable biological activities in protecting liver, relieving alcoholism, antioxidation, anti-tumor and anti-inflammation in clinic. However, the potential mechanism of ethyl acetate extract of Pueraria lobata after 70% alcohol extraction (APL) ameliorating nonalcoholic fatty liver disease (NAFLD) has not been clarified.

AIM OF THE STUDY

This study aimed to investigate the ameliorative effect of P. lobata extract on human hepatoma cells and injury in rats, and to evaluate its therapeutic potential for ameliorating NAFLD.

METHODS

Firstly, the effective part of P. lobata extract was determined as APL by measuring its total substances and antioxidant activity. And then the in vitro and in vivo models of NAFLD were adopted., HepG2 cells were incubated with palmitic acid (PA) and hydrogen peroxide (H2O2). In order to evaluate the effect of APL, Simvastatin and Vitamin C (VC) were used as positive control. Various parameters related to lipogenesis and fatty acid β-oxidation were studied, such as intracellular lipid accumulation, reactive oxygen species (ROS), Western Blot, mitochondrial membrane potential, apoptosis, and the mechanism of APL improving NAFLD. The chemical components of APL were further determined by HPLC and UPLC-MS, and molecular docking was carried out with Keap1/Nrf2/HO-1 pathway related proteins.

RESULTS

APL significantly reduced lipid accumulation and levels of oxidative stress-related factors in vitro and in vivo. Immunohistochemical、Western Blot and PCR analysis showed that the expressions of Nrf2 and HO-1 were up-regulated in APL treatment. The Nrf2 inhibitor ML385 can block the rescue by APL of cellular oxidative stress and lipid accumulation induced by H2O2 and PA, demonstrating its dependence on Nrf2. UPLC/MS analysis showed that there were 3'-hydroxyl puerarin, puerarin, 3'-methoxy puerarin, daidzein, genistin, ononin, daidzin and genistein.

CONCLUSION

This study further clarified the mechanism of P. lobata extract in improving NAFLD, which provided a scientific basis for developing new drugs to protect liver injury and laid a solid foundation for developing P. lobata Chinese herbal medicine resources.

Total flavonoids of Broussonetia papyrifera alleviate non-alcohol fatty liver disease via regulating Nrf2/AMPK/mTOR signaling pathways

BACKGROUNDS

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases. The leaves of Broussonetia papyrifera contain a large number of flavonoids, which have a variety of biological functions.

METHODS

In vitro experiments, free fatty acids were used to stimulate HepG2 cells. NAFLD model was established in vivo in mice fed with high fat diet (HFD) or intraperitoneally injected with Tyloxapol (Ty). At the same time, Total flavonoids of Broussonetia papyrifera (TFBP) was used to interfere with HepG2 cells or mice.

RESULTS

The results showed that TFBP significantly decreased the lipid accumulation induced by oil acid (OA) with palmitic acid (PA) in HepG2 cells. TFBP decreased the total cholesterol (TC), the triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and increased high-density lipoprotein cholesterol (HDLC) in serum. TFBP could also effectively inhibit the generation of reactive oxygen species (ROS) and restrained the level of myeloperoxidase (MPO), and enhance the activity of superoxide dismutase (SOD) to alleviate the injury from oxidative stress in the liver. Additionally, TFBP activated nuclear factor erythroid-2-related factor 2 (Nrf2) pathway to increasing the phosphorylation of AMP-activated protein kinase (AMPK). Meanwhile, protein levels of mTORC signaling pathway were evidently restrained with the treatment of TFBP.

CONCLUSION

Our experiments proved that TFBP has the therapeutic effect in NAFLD, and the activation of Nrf2 and AMPK signaling pathways should make sense.

Natural products as non-covalent and covalent modulators of the KEAP1/NRF2 pathway exerting antioxidant effects

By controlling several antioxidant and detoxifying genes at the transcriptional level, including NAD(P)H quinone oxidoreductase 1 (NQO1), multidrug resistance-associated proteins (MRPs), UDP-glucuronosyltransferase (UGT), glutamate-cysteine ligase catalytic (GCLC) and modifier (GCLM) subunits, glutathione S-transferase (GST), sulfiredoxin1 (SRXN1), and heme-oxygenase-1 (HMOX1), the KEAP1/NRF2 pathway plays a crucial role in the oxidative stress response. Accordingly, the discovery of modulators of this pathway, activating cellular signaling through NRF2, and targeting the antioxidant response element (ARE) genes is pivotal for the development of effective antioxidant agents. In this context, natural products could represent promising drug candidates for supplementation to provide antioxidant capacity to human cells. In recent decades, by coupling in silico and experimental methods, several natural products have been characterized to exert antioxidant effects by targeting the KEAP1/NRF2 pathway. In this review article, we analyze several natural products that were investigated experimentally and in silico for their ability to modulate KEAP1/NRF2 by non-covalent and covalent mechanisms. These latter represent the two main sections of this article. For each class of inhibitors, we reviewed their antioxidant effects and potential therapeutic applications, and where possible, we analyzed the structure-activity relationship (SAR). Moreover, the main computational techniques used for the most promising identified compounds are detailed in this survey, providing an updated view on the development of natural products as antioxidant agents.

Pharmacology of bioactive compounds from plant extracts for improving non-alcoholic fatty liver disease through endoplasmic reticulum stress modulation: A comprehensive review

Background

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver condition with significant clinical implications. Emerging research indicates endoplasmic reticulum (ER) stress as a critical pathogenic factor governing inflammatory responses, lipid metabolism and insulin signal transduction in patients with NAFLD. ER stress-associated activation of multiple signal transduction pathways, including the unfolded protein response, disrupts lipid homeostasis and substantially contributes to NAFLD development and progression. Targeting ER stress for liver function enhancement presents an innovative therapeutic strategy. Notably, the natural bioactive compounds of plant extracts have shown potential for treating NAFLD by reducing the level of ER stress marker proteins and mitigating inflammation, stress responses, and de novo lipogenesis. However, owing to limited comprehensive reviews, the effectiveness and pharmacology of these bioactive compounds remain uncertain.

Objectives

To address the abovementioned challenges, the current review categorizes the bioactive compounds of plant extracts by chemical structures and properties into flavonoids, phenols, terpenoids, glycosides, lipids and quinones and examines their ameliorative potential for NAFLD under ER stress.

Methods

This review systematically analyses the literature on the interactions of bioactive compounds from plant extracts with molecular targets under ER stress, providing a holistic view of NAFLD therapy.

Results

Bioactive compounds from plant extracts may improve NAFLD by alleviating ER stress; reducing lipid synthesis, inflammation, oxidative stress and apoptosis and enhancing fatty acid metabolism. This provides a multifaceted approach for treating NAFLD.

Conclusion

This review underscores the role of ER stress in NAFLD and the potential of plant bioactive compounds in treating this condition. The molecular mechanisms by which plant bioactive compounds interact with their ER stress targets provide a basis for further exploration in NAFLD management.

Mechanism of Action and Related Natural Regulators of Nrf2 in Nonalcoholic Fatty Liver Disease

With the acceleration of people's pace of life, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the world, which greatly threatens people's health and safety. Therefore, there is still an urgent need for higher-quality research and treatment in this area. Nuclear factor Red-2-related factor 2 (Nrf2), as a key transcription factor in the regulation of oxidative stress, plays an important role in inducing the body's antioxidant response. Although there are no approved drugs targeting Nrf2 to treat NAFLD so far, it is still of great significance to target Nrf2 to alleviate NAFLD. In recent years, studies have reported that many natural products treat NAFLD by acting on Nrf2 or Nrf2 pathways. This article reviews the role of Nrf2 in the pathogenesis of NAFLD and summarizes the currently reported natural products targeting Nrf2 or Nrf2 pathway for the treatment of NAFLD, which provides new ideas for the development of new NAFLD-related drugs.

The Different Mechanisms of Lipid Accumulation in Hepatocytes Induced by Oleic Acid/Palmitic Acid and High-Fat Diet

Non-alcoholic fatty liver disease (NAFLD) is the primary chronic liver disease worldwide, mainly manifested by hepatic steatosis. Hepatic lipids may be derived from dietary intake, plasma free fatty acid (FFA) uptake, or hepatic de novo lipogenesis (DNL). Currently, cellular and animal models of hepatocellular steatosis are widely used to study the pathogenesis of NAFLD and to investigate therapeutic agents. However, whether there are differences between the in vivo and in vitro models of the mechanisms that cause lipid accumulation has not been reported. We used OA/PA-induced NCTC 1469 cells and high-fat-diet-fed C57BL/6J mice to simulate a hepatocyte steatosis model of NAFLD and to detect indicators related to FFA uptake and DNL. In addition, when serological indicators were analysed in the mouse model, it was found that serum FASN levels decreased. The results revealed that, in the cellular model, indicators related to DNL were decreased, FASN enzyme activity was unchanged, and indicators related to FFA uptake were increased, including the high expression of CD36; while, in the animal model, indicators related to both FFA uptake and de novo synthesis were increased, including the high expression of CD36 and the increased protein levels of FASN with enhanced enzyme activity. In addition, after an analysis of the serological indicators in the mouse model, it was found that the serum levels of FASN were reduced. In conclusion, the OA/PA-induced cellular model can be used to study the mechanism of FFA uptake, whereas the high-fat-diet-induced mouse model can be used to study the mechanism of FFA uptake and DNL. Combined treatment with CD36 and FASN may be more effective against NAFLD. FASN in the serum can be used as one of the indicators for the clinical diagnosis of NAFLD.

Gas Chromatography-Mass Spectrometry-Based Cerebrospinal Fluid Metabolomics to Reveal the Protection of Coptisine against Transient Focal Cerebral Ischemia-Reperfusion Injury via Anti-Inflammation and Antioxidant

Coptisine (Cop) exerts a neuroprotective effect on central nervous system disease, particularly ischemic stroke. However, its protective mechanism is still unclear. This study aimed to investigate the protective effect of Cop on cerebral ischemia-reperfusion (IR) rats with a middle cerebral artery occlusion model by integrating a gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach with biochemical assessment. Our results showed that Cop could improve neurobehavioral function and decrease the ischemia size in IR rats. In addition, Cop was found to decrease inflammatory mediators (e.g., prostaglandin D2 (PGD2) and tumor necrosis factor-α (TNF-α) and attenuate oxidative stress response (e.g., increase the superoxide dismutase (SOD) expression and decrease 8-iso-PGF2α level). Furthermore, the GC-MS-based cerebrospinal fluid (CSF) metabolomics analysis indicated that Cop influenced the level of glycine, 2,3,4-trihydroxybutyric acid, oleic acid, glycerol, and ribose during IR injury. Cop exhibited a good neuroprotective effect against cerebral IR injury and metabolic alterations, which might be mediated through its antioxidant and anti-inflammatory properties.

Tuberostemonine alleviates high-fat diet-induced obesity and hepatic steatosis by increasing energy consumption

Obesity is of public concern worldwide, and it increases the probability of developing a number of comorbid diseases, including NAFLD. Recent research on obesity drugs and health demands have shown the potential of natural plant extracts for preventing and treating obesity and their lack of toxicity and treatment-related side effects. We have demonstrated that tuberostemonine (TS), an alkaloid extracted from the traditional Chinese medicine Stemona tuberosa Lour can inhibit intracellular fat deposition, reduce oxidative stress, increase cellular adenosine triphosphate (ATP), and increase mitochondrial membrane potential. It effectively reduced weight gain and fat accumulation caused by a high-fat diet, and regulated liver function and blood lipid levels. Moreover, it regulate glucose metabolism and improved energy metabolism in mice. TS also decreased high-fat diet-induced obesity and improved lipid and glucose metabolism disorders in mice, with no significant side effects. In conclusion, TS was shown to be a safe alternative for obese patients and might be developed as an antiobesity and anti-nonalcoholic fatty liver drug.

α-Lactalbumin Peptide Asp-Gln-Trp Ameliorates Hepatic Steatosis and Oxidative Stress in Free Fatty Acids-Treated HepG2 Cells and High-Fat Diet-Induced NAFLD Mice by Activating the PPARα Pathway

SCOPE

Dietary intervention has emerged as a promising strategy for the management of nonalcoholic fatty liver disease (NAFLD). The aim of this study is to investigate the ameliorative effects of the α-lactalbumin peptide Asp-Gln-Trp (DQW) against NAFLD and the underlying mechanism.

METHODS AND RESULTS

The models of lipid metabolism disorders are established both in HepG2 cells and in C57BL/6J mice. The results demonstrate that DQW activates peroxisome proliferator-activated receptor α (PPARα) and subsequently ameliorates lipid deposition and oxidative stress in vitro. Interestingly, GW6471 markedly attenuates the modulatory effects of DQW on the PPARα pathway in HepG2 cells. Moreover, results of in vivo experiments indicate that DQW alleviates body weight gain, dyslipidemia, hepatic steatosis, and oxidative stress in high-fat-diet (HFD)-induced NAFLD mice. At the molecular level, DQW activates PPARα, subsequently enhances fatty acid β-oxidation, and reduces lipogenesis, thereby ameliorating hepatic steatosis. Meanwhile, DQW may ameliorate liver injury and oxidative stress via activating the PPARα/nuclear-factor erythroid 2 (Nrf2)/heme-oxygenase 1 (HO-1) pathway.

CONCLUSION

Those results indicate that α-lactalbumin peptide DQW may be an effective dietary supplement for alleviating NAFLD by alleviating lipid deposition and oxidative stress.

Aescin can alleviate NAFLD through Keap1-Nrf2 by activating antioxidant and autophagy

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common metabolic liver disease worldwide. It has been proven that aescin (Aes), a bioactive compound derived from the ripe dried fruit of Aesculus chinensis Bunge, has a number of physiologically active properties like anti-inflammatory and anti-edema, however it has not been investigated as a potential solution for NAFLD.

PURPOSE

This study's major goal was to determine whether Aes can treat NAFLD and the mechanism underlying its therapeutic benefits.

METHODS

We constructed HepG2 cell models in vitro that were affected by oleic and palmitic acids, as well as in vivo models for acute lipid metabolism disorder caused by tyloxapol and chronic NAFLD caused by high-fat diet.

RESULTS

We discovered that Aes could promote autophagy, activate the Nrf2 pathway, and ameliorate lipid accumulation and oxidative stress both in vitro and in vivo. Nevertheless, in Autophagy-related proteins 5 (Atg5) and Nrf2 knockout mice, Aes lost its curative impact on NAFLD. Computer simulations show that Aes might interact with Keap1, which might allow Aes to increase Nrf2 transfer into the nucleus and perform its function. Importantly, Aes's stimulation of autophagy in the liver was hampered in Nrf2 knockout mice. This suggested that the impact of Aes in inducing autophagy may be connected to the Nrf2 pathway.

CONCLUSION

We first discovered Aes's regulating effects on liver autophagy and oxidative stress in NAFLD. And we found Aes may combine the Keap1 and regulate autophagy in the liver by affecting Nrf2 activation to exert its protective effect.

The Effect of Bioactive Aliment Compounds and Micronutrients on Non-Alcoholic Fatty Liver Disease

In the current review, we focused on identifying aliment compounds and micronutrients, as well as addressed promising bioactive nutrients that may interfere with NAFLD advance and ultimately affect this disease progress. In this regard, we targeted: 1. Potential bioactive nutrients that may interfere with NAFLD, specifically dark chocolate, cocoa butter, and peanut butter which may be involved in decreasing cholesterol concentrations. 2. The role of sweeteners used in coffee and other frequent beverages; in this sense, stevia has proven to be adequate for improving carbohydrate metabolism, liver steatosis, and liver fibrosis. 3. Additional compounds were shown to exert a beneficial action on NAFLD, namely glutathione, soy lecithin, silymarin, Aquamin, and cannabinoids which were shown to lower the serum concentration of triglycerides. 4. The effects of micronutrients, especially vitamins, on NAFLD. Even if most studies demonstrate the beneficial role of vitamins in this pathology, there are exceptions. 5. We provide information regarding the modulation of the activity of some enzymes related to NAFLD and their effect on this disease. We conclude that NAFLD can be prevented or improved by different factors through their involvement in the signaling, genetic, and biochemical pathways that underlie NAFLD. Therefore, exposing this vast knowledge to the public is particularly important.

Flavonoids from Scutellaria amoena C. H. Wright alleviate mitochondrial dysfunction and regulate oxidative stress via Keap1/Nrf2/HO-1 axis in rats with high-fat diet-induced nonalcoholic steatohepatitis

BACKGROUND

Nonalcoholic steatohepatitis (NASH) is among the most common liver diseases in the world. Flavonoids from Scutellaria amoena (SAF) are used in the treatment of hepatopathy in China. However, the effect and mechanism against NASH remain unclear. We investigated the alleviating effect of SAF on NASH via regulating mitochondrial dysfunction and oxidative stress.

METHODS

The effects of SAF on NASH were evaluated using in vitro and in vivo methods. L02 cells were induced by fat emulsion to establish an adipocytes model, followed by treatment with SAF for 24 h. NASH rat models were established by the administration of a high-fat diet for 12 weeks and were administered SAF for six weeks. Changes in body weight, organ indexes, lipid levels, inflammatory cytokines, mitochondrial indicators, and fatty acid metabolism were investigated.

RESULTS

SAF significantly improved body weight, organ indexes, lipid levels, liver injury, and inflammatory infiltration in NASH rats. SAF notably regulated interleukin-6, tumor necrotic factor-alpha, superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), kelch-like ECH-associated protein 1 (Keap1), nuclear factor-erythroid factor 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1). Additionally, SAF improved mitochondrial dysfunction, increased the levels of GSH, SOD, ATP synthase, complex I and II, and decreased the level of MDA in liver mitochondria. SAF regulated the expression of β-oxidation genes, including peroxisome proliferator-activated receptor -gamma coactivator-1alpha (PGC-1α), carnitine palmitoyltransferase-1 (CPT1) A, CPT1B, medium-chain acyl-CoA dehydrogenase, long-chain acyl-CoA dehydrogenase, very long-chain acyl-CoA dehydrogenase, and PPARα.

CONCLUSION

SAF can alleviate NASH by regulating mitochondrial function and oxidative stress via the Keap1/Nrf2/HO-1 axis.

Role of Nrf2 and HO-1 in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a common age-related disease with clinical manifestations of lumbar and leg pain and limited mobility. The pathogenesis of IDD is mainly mediated by the death of intervertebral disc (IVD) cells and the imbalance of extracellular matrix (ECM) synthesis and degradation. Oxidative stress and inflammatory reactions are the important factors causing this pathological change. Therefore, the regulation of reactive oxygen species and production of inflammatory factors may be an effective strategy to delay the progression of IDD. In recent years, nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream regulated protein heme oxygenase-1 (HO-1) have received special attention due to their antioxidant, anti-inflammatory and anti-apoptotic protective effects. Recent studies have elucidated the important role of these two proteins in the treatment of IDD disease. However, Nrf2 and HO-1 have not been systematically reported in IDD-related diseases. Therefore, this review describes the biological characteristics of Nrf2 and HO-1, the relationship between Nrf2- and HO-1-regulated oxidative stress and the inflammatory response and IDD, and the progress in research on some extracts targeting Nrf2 and HO-1 to improve IDD. Understanding the role and mechanism of Nrf2 and HO-1 in IDD may provide novel ideas for the clinical treatment and development of Nrf2- and HO-1-targeted drugs.

1,3-Dichloro-2-propanol-Induced Renal Tubular Cell Necroptosis through the ROS/RIPK3/MLKL Pathway

1,3-Dichloro-2-propanol (1,3-DCP), as a food pollutant, exists in a variety of foods. Studies have shown that it has nephrotoxicity. In the study, we found that 1,3-DCP caused renal injury with necroptosis in C57BL/6J mice. The mechanism of 1,3-DCP-caused nephrotoxicity was further explored in NRK-52E cells in vitro. We found that 1,3-DCP caused cell necroptosis with the increase in lactate dehydrogenase (LDH) levels and the expressions of RIPK3 and MLKL. But pretreatment with a ROS inhibitor N-acetyl-l-cysteine (NAC), a RIPK3 inhibitor GSK'872, or RIPK3 gene silencing alleviated 1,3-DCP-induced cell necroptosis. The data indicated that 1,3-DCP induced necroptosis through the ROS/RIPK3/MLKL pathway in NRK-52E cells. In further mechanistic studies, we explored how 1,3-DCP induced ROS production. We found that 1,3-DCP inhibited the expressions of nuclear and cytoplasmic Nrf2. But pretreatment with an Nrf2 activator dimethyl fumarate (DMF) up-regulated the expressions of nuclear and cytoplasmic Nrf2 and down-regulated ROS levels and RIPK3 and MLKL expressions. We also examined the effects of mitophagy on 1,3-DCP-induced ROS. The data manifested that 1,3-DCP suppressed mitophagy in NRK-52E cells by decreasing LC3-II, Pink1, and Parkin levels, increasing p62 levels, and decreasing colocalization of LC3 and Mito-Tracker Red. Pretreatment with an autophagy activator rapamycin (Rapa) decreased 1,3-DCP-induced ROS. Taken together, our data identified that 1,3-DCP caused renal necroptosis through the ROS/RIPK3/MLKL pathway.

Astaxanthin Alleviates Nonalcoholic Fatty Liver Disease by Regulating the Intestinal Flora and Targeting the AMPK/Nrf2 Signal Axis

Nonalcoholic fatty liver disease (NAFLD) is among the most prevalent chronic liver diseases around the globe. The accumulation of lipids in the liver and oxidative stress are important pathological mechanisms of NAFLD. Astaxanthin (AT) is a carotenoid extracted from shrimps and crabs with beneficial biological activities, including anti-oxidative and anti-inflammatory activities. 16S microflora sequencing, H&E staining, and the western blot technique were employed to investigate the impacts of AT on a high-fat diet (HFD)-induced NAFLD. Significant mitigation in lipid metabolism-related disorders and decreased oxidative stress in HFD-induced mice were observed due to AT, and significant changes in the gut flora of the model mice were also observed. The in vitro study showed that AT considerably lowered the protein expression level of fatty acid synthetase (FAS), sterol regulatory element-binding protein-1c (SREBP-1c), and acetyl-COA carboxylase (ACC) and increased the protein expression of nuclear factor-E2 associated factor 2 (Nrf2) and AMP-activated protein kinase (AMPK) in oleic acid (OA) and palmitic acid (PA)-induced HepG2 cells. Additionally, mechanistic studies revealed that compound C (AMPK inhibitor, CC) inhibited the regulatory effect of AT on the SREBP-1c and Nrf2 signaling pathways. In conclusion, AT can inhibit the SREBP-1c, FAS, and ACC signaling pathways, activate the AMPK and Nrf2 signaling pathways, and improve the structure of intestinal flora.

Triptolide Induces Liver Injury by Regulating Macrophage Recruitment and Polarization via the Nrf2 Signaling Pathway

Triptolide (TP) has limited usage in clinical practice due to its side effects and toxicity, especially liver injury. Hepatic macrophages, key player of liver innate immunity, were found to be recruited and activated by TP in our previous study. The nuclear factor-erythroid-2-related factor 2 (Nrf2) pathway exerts a protective role in TP-induced liver damage, but its effect on the functions of hepatic macrophage has not been elucidated. Here, we determined whether TP can regulate the recruitment and polarization of hepatic macrophages by inhibiting Nrf2 signaling cascade. Our results demonstrated that TP inhibited the Nrf2 signaling pathway in hepatic macrophages. The changes in hepatic macrophages were responsible for the increased susceptibility toward inflammatory stimuli, and hence, TP pretreatment could induce severe liver damage upon the stimulation of a nontoxic dose of lipopolysaccharides. In addition, the Nrf2 agonist protected macrophages from TP-induced toxicity and Nrf2 deficiency significantly aggravated liver injury by enhancing the recruitment and M1 polarization of hepatic macrophages. This study suggests that Nrf2 pathway-mediated hepatic macrophage polarization plays an essential role in TP-induced liver damage, which can serve as a potential therapeutic target for preventing hepatotoxicity induced by TP.