NF-E2-related factor 2 inhibits lipid accumulation and oxidative stress in mice fed a high-fat diet

Plant-derived bioactive peptides and protein hydrolysates for managing MAFLD: A systematic review of in vivo effects

Metabolic dysfunction-associated fatty liver disease (MAFLD) represents a growing health concern worldwide. Among the pursuit of therapeutic interventions, interest in natural bioactive compounds has intensified because of their potential hepatoprotective effects. This systematic review aims to evaluate the impact of plant-derived hydrolysates and peptides on MAFLD through the current literatures, encompassing their mechanisms of action. Key outcomes evaluated included changes in liver enzymes, liver lipid content, inflammation markers, and histopathological improvements. Preliminary findings suggest a potential beneficial effect of plant-derived hydrolysates and peptides on the improvement of MAFLD-related parameters, with mechanisms implicating antioxidant, anti-inflammatory, and lipid-lowering properties. This review highlights emerging evidence supporting the potential therapeutic role of plant-derived hydrolysates and peptides in the management of MAFLD. However, more well-designed clinical trials with larger sample sizes and longer durations are warranted to elucidate their efficacy, optimal dose, and long-term safety.

l-Arginine: A multifaceted regulator of diabetic cardiomyopathy

In diabetes mellitus, dysregulated glucose and lipid metabolism lead to diabetic cardiomyopathy (DCM) by imparting pathological myocardial remodeling and cellular injury. Accelerated glycation, oxidative stress, and activated inflammatory pathways culminate in cardiac fibrosis and hypertrophy in DCM. The regulatory effects of l-Arginine (L-Arg) have been elucidated in the pathological changes of DCM, including myocardial fibrosis, hypertrophy, and apoptosis, by inhibiting glycation and oxidative stress-induced inflammation. Disturbed L-Arg metabolism and decreased intracellular L-Arg pool are correlated with the progression of DCM; therefore, L-Arg supplementation has been prescribed for various cardiovascular dysfunctions. This review expands the therapeutic potential of L-Arg supplementation in DCM by elucidating its molecular mechanism of action and exploring potential clinical outcomes.

A strategy for liver selective NRF2 induction via cytochrome P450 activated prodrugs with low activity in hypoxia

Activation of the transcription factor NRF2 has been shown to be a promising therapeutic approach in the treatment of hepatosteatosis. NRF2 is believed to exert beneficial effects by upregulating cellular oxidative defense mechanisms and inhibiting inflammation. However, a major concern associated with long-term treatment with NRF2 activators are drug side effects, including the promotion of tumorigenesis. Many NRF2 activators function by forming cysteine adducts with KEAP1, which normally mediates the ubiquitination and degradation of NRF2. In this study we identified NRF2 activator prodrugs of 4-methylcatechol and tert-butylhydroquinone. These prodrugs are converted into their active metabolites in a liver selective, cytochrome P450 dependent manner and function by inhibiting KEAP1, resulting in NRF2 activation. Unexpectedly, we also found that a number of NRF2 activating compounds, including 4-methylcatechol and tert-butylhydroquinone, show a markedly lower activity under hypoxic conditions compared to normoxia. Our findings suggest that the lower activity of these NRF2 inducers is a consequence of less potent cysteine adduct formation with KEAP1. The lower activity of NRF2 inducing compounds in hypoxia may limit tumor promoting effects of NRF2 induction. Our study provides an important proof of concept that it is possible to selectively activate NRF2 in the liver for the treatment of hepatosteatosis while avoiding tumorigenic effects as well as side effects of NRF2 activation in other tissues.

Lipid metabolism, remodelling and intercellular transfer in the CNS

Lipid metabolism encompasses the catabolism and anabolism of lipids, and is fundamental for the maintenance of cellular homeostasis, particularly within the lipid-rich CNS. Increasing evidence further underscores the importance of lipid remodelling and transfer within and between glial cells and neurons as key orchestrators of CNS lipid homeostasis. In this Review, we summarize and discuss the complex landscape of processes involved in lipid metabolism, remodelling and intercellular transfer in the CNS. Highlighted are key pathways, including those mediating lipid (and lipid droplet) biogenesis and breakdown, lipid oxidation and phospholipid metabolism, as well as cell-cell lipid transfer mediated via lipoproteins, extracellular vesicles and tunnelling nanotubes. We further explore how the dysregulation of these pathways contributes to the onset and progression of neurodegenerative diseases, and examine the homeostatic and pathogenic impacts of environment, diet and lifestyle on CNS lipid metabolism.

Melatonin induces fiber switching by improvement of mitochondrial oxidative capacity and function via NRF2/RCAN/MEF2 in the vastus lateralis muscle from both sex Zücker diabetic fatty rats

The positive role of melatonin in obesity control and skeletal muscle (SKM) preservation is well known. We recently showed that melatonin improves vastus lateralis muscle (VL) fiber oxidative phenotype. However, fiber type characterization, mitochondrial function, and molecular mechanisms that underlie VL fiber switching by melatonin are still undefined. Our study aims to investigate whether melatonin induces fiber switching by NRF2/RCAN/MEF2 pathway activation and mitochondrial oxidative metabolism modulation in the VL of both sex Zücker diabetic fatty (ZDF) rats. 5-Weeks-old male and female ZDF rats (N = 16) and their age-matched lean littermates (ZL) were subdivided into two subgroups: control (C) and orally treated with melatonin (M) (10 mg/kg/day) for 12 weeks. Interestingly, melatonin increased oxidative fibers amounts (Types I and IIa) counteracting the decreased levels found in the VL of obese-diabetic rats, and upregulated NRF2, calcineurin and MEF2 expression. Melatonin also restored the mitochondrial oxidative capacity increasing the respiratory control ratio (RCR) in both sex and phenotype rats through the reduction of the proton leak component of respiration (state 4). Melatonin also improved the VL mitochondrial phosphorylation coefficient and modulated the total oxygen consumption by enhancing complex I, III and IV activity, and fatty acid oxidation (FAO) in both sex obese-diabetic rats, decreasing in male and increasing in female the complex II oxygen consumption. These findings suggest that melatonin treatment induces fiber switching in SKM improving mitochondrial functionality by NRF2/RCAN/MEF2 pathway activation.

Model organisms for investigating the functional involvement of NRF2 in non-communicable diseases

Non-communicable chronic diseases (NCDs) are most commonly characterized by age-related loss of homeostasis and/or by cumulative exposures to environmental factors, which lead to low-grade sustained generation of reactive oxygen species (ROS), chronic inflammation and metabolic imbalance. Nuclear factor erythroid 2-like 2 (NRF2) is a basic leucine-zipper transcription factor that regulates the cellular redox homeostasis. NRF2 controls the expression of more than 250 human genes that share in their regulatory regions a cis-acting enhancer termed the antioxidant response element (ARE). The products of these genes participate in numerous functions including biotransformation and redox homeostasis, lipid and iron metabolism, inflammation, proteostasis, as well as mitochondrial dynamics and energetics. Thus, it is possible that a single pharmacological NRF2 modulator might mitigate the effect of the main hallmarks of NCDs, including oxidative, proteostatic, inflammatory and/or metabolic stress. Research on model organisms has provided tremendous knowledge of the molecular mechanisms by which NRF2 affects NCDs pathogenesis. This review is a comprehensive summary of the most commonly used model organisms of NCDs in which NRF2 has been genetically or pharmacologically modulated, paving the way for drug development to combat NCDs. We discuss the validity and use of these models and identify future challenges.

Eye on the horizon: The metabolic landscape of the RPE in aging and disease

To meet the prodigious bioenergetic demands of the photoreceptors, glucose and other nutrients must traverse the retinal pigment epithelium (RPE), a polarised monolayer of cells that lie at the interface between the outer retina and the choroid, the principal vascular layer of the eye. Recent investigations have revealed a metabolic ecosystem in the outer retina where the photoreceptors and RPE engage in a complex exchange of sugars, amino acids, and other metabolites. Perturbation of this delicate metabolic balance has been identified in the aging retina, as well as in age-related macular degeneration (AMD), the leading cause of blindness in the Western world. Also common in the aging and diseased retina are elevated levels of cytokines, oxidative stress, advanced glycation end-products, increased growth factor signalling, and biomechanical stress - all of which have been associated with metabolic dysregulation in non-retinal cell types and tissues. Herein, we outline the role of these factors in retinal homeostasis, aging, and disease. We discuss their effects on glucose, mitochondrial, lipid, and amino acid metabolism in tissues and cell types outside the retina, highlighting the signalling pathways through which they induce these changes. Lastly, we discuss promising avenues for future research investigating the roles of these pathological conditions on retinal metabolism, potentially offering novel therapeutic approaches to combat age-related retinal disease.

Delphinidin or α-amyrin attenuated liver steatosis and metabolic disarrangement in rats fed a high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is a liver pathology concomitant with metabolic disarrangement. This study assessed the therapeutic impacts of delphinidin, an anthocyanin, or α-amyrin, a pentacyclic triterpenoid, on NAFLD in rats and the underlying mechanisms involved. NAFLD was established by feeding a high-fat diet (HFD) for 10 weeks, either alone or in combination with delphinidin (40 mg/kg, oral) or α-amyrin (20 mg/kg, oral). Delphinidin or α-amyrin ameliorated the metabolic and histopathological perturbations induced by HFD. These compounds markedly attenuated NAFLD-induced hepatic steatosis, as evidenced by a substantial decrease in body weight, insulin resistance, and liver and adipose tissue indices. Alongside normalization of the atherogenic index, both improved HFD-mediated abnormalities in serum lipids, liver enzymes, leptin, and ghrelin levels. Moreover, their intervention activated the NFE2 like bZIP transcription factor 2 and heme oxygenase 1 pathways and abrogated HFD-triggered activation of mitogen-activated protein kinase 1 signaling. These remedies inhibited hepatic apoptosis and modulated the gene expression of lipogenic enzymes. Furthermore, histological analysis corroborated the suppression of lipid accumulation and amelioration of hepatic architecture in the treated rats. Our findings highlight the hepatoprotective value of delphinidin or α-amyrin against NAFLD and related metabolic diseases through their insulin-sensitizing, anti-inflammatory, antioxidant, and antiapoptotic effects.

Media Supplementation With Gamma-Oryzanol Improves the Outcome of Ovine Oocyte Maturation In Vitro

BACKGROUND

The process of maturing ovine oocyte in vitro has not yet been raised with acceptable results.

OBJECTIVE

This study was designed to evaluate the γ-oryzanol effect as a supplement of maturation media on the development of ovine oocytes to blastocyst.

METHODS

Aspirated from ovine ovaries, morphologically normal cumulus-oocyte complexes (COCs) were matured in media supplemented with or without 5 µM γ-oryzanol. Matured oocytes were divided into two parts: one evaluated for their nuclear maturation, the level of GSH and ROS, mitochondrial membrane potential (MMP) and the pattern of transcription in oocytes and respective cumulus cells (CCs), and another subjected to fertilisation and culture to assess the development of oocytes to the blastocyst.

RESULTS

γ-Oryzanol improved the proportion of cleaved embryos and total blastocysts in the treated group, which was linked to improved MMP, higher levels of intracellular GSH and lower levels of ROS. A lower proportion of MI and GVBD was recorded for treated oocytes in comparison with control, although the proportion of MII oocytes was not different between groups. The treated oocytes and CCs showed downregulation of genes related to apoptosis (BAX and CASP-9) and upregulation of genes related to antioxidative status (NRF2, CAT and SOD). In conclusion, our results demonstrated the improved developmental outcome of supplemented oocytes so that the antioxidant response and higher enzymatic activity were maintained, and the generation of ROS was turned off; therefore, a novel alternative for counteracting oxidative stress in ovine oocytes undergoing maturation was offered by γ-oryzanol through an antioxidative pathway.

The NRF-2/HO-1 Signaling Pathway: A Promising Therapeutic Target for Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive liver disorder with a rising prevalence. It begins with lipid accumulation in hepatocytes and gradually progresses to Metabolic-associated steatohepatitis (MASH), fibrosis, cirrhosis, and potentially hepatocellular carcinoma (HCC). The pathophysiology of MASLD is complex and involves multiple factors, with oxidative stress playing a crucial role. Oxidative stress drives the progression of MASLD by causing cellular damage, inflammatory responses, and fibrosis, making it a key pathogenic mechanism. The Nuclear Factor Erythroid 2-Related Factor 2 / Heme Oxygenase-1 (Nrf2/HO-1) signaling axis provides robust multi-organ protection against a spectrum of endogenous and exogenous insults, particularly oxidative stress. It plays a pivotal role in mediating antioxidant, anti-inflammatory, and anti-apoptotic responses. Many studies indicate that activating the Nrf2/HO-1 signaling pathway can significantly mitigate the progression of MASLD. This article examines the role of the Nrf2/HO-1 signaling pathway in MASLD and highlights natural compounds that protect against MASLD by targeting Nrf2/HO-1 activation. The findings indicate that the Nrf2/HO-1 signaling pathway holds great promise as a therapeutic target for MASLD.

Molecular mechanism of ectopic lipid accumulation induced by methylglyoxal via activation of the NRF2/PI3K/AKT pathway implicates renal lipotoxicity caused by diabetes mellitus

Patients with chronic kidney disease (CKD) have a high incidence of dyslipidemia comprising high triglyceride (TG) and low high-density lipoprotein (HDL)-cholesterol levels. An abnormal increase of TGs within cells can lead to intracellular lipid accumulation. In addition to dyslipidemia, hyperglycemia in diabetes may elicit ectopic lipid deposition in non-adipose tissues. Hyperglycemia increases intracellular levels of methylglyoxal (MG) leading to cellular dysfunction. A deficit of glyoxalase I (GLO1) contributes to dicarbonyl stress. Whether dicarbonyl stress induced by MG causes renal lipotoxicity through alteration of lipid metabolism signaling is still unknown. In this study, mice with high fat diet-induced diabetes were used to investigate the renal pathology induced by MG. NRK52E cells treated with MG were further used in vitro to delineate the involvement of lipogenic signaling. After treatment with MG for 12 weeks, plasma TG levels, renal fatty changes, and tubular injuries were aggravated in diabetic mice. In NRK52E cells, MG activated the nuclear factor erythroid 2-related factor 2 (Nrf2)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and sterol regulatory element-binding protein 1 (SREBP1), resulting in stimulation of fatty acid synthase. The intracellular accumulation of lipid droplets was mainly contributed by TGs, which increased the oxidative stress accompanied by high Nrf2 expression. In addition, MG time-dependently activated cyclin D, cyclin-dependent kinase 4 (CDK4), and cleaved caspase-3, evidencing that G0/G1 arrest was associated with apoptosis of NRK52E cells. In conclusion, our studies revealed the mechanism of lipotoxicity caused by MG. The target of such dicarbonyl stress may become a promising therapy for diabetic CKD.

Overweight and obesity significantly increase colorectal cancer risk: a meta-analysis of 66 studies revealing a 25-57% elevation in risk

The incidence of colorectal cancer (CRC) has been steadily rising, and obesity has been identified as a significant risk factor. Numerous studies suggest a strong correlation between excess body weight and increased risk of CRC, but comprehensive quantification through pooled analysis remains limited. This study aims to systematically review and meta-analyze the existing literature to evaluate the association between obesity and CRC risk, considering variations across sex and study designs. A systematic literature search was conducted in PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science to identify randomized controlled trials and human clinical trials from 1992 to 2024. Statistical analysis was performed using the https://metaanalysisonline.com web application using a random effects model to estimate the pooled hazard rates (HR). Forest plots, funnel plots, and Z-score plots were utilized to visualize results. We identified 52 clinical trials and 14 case-control studies, encompassing a total of 83,251,050 and 236,877 subjects, respectively. The pooled analysis indicated that obesity significantly increased the prevalence of CRC (HR = 1.36, 95% CI = 1.24-1.48, p < 0.01). This effect was consistent across sexes, with HRs of 1.57 (95% CI = 1.38-1.78, p = 0.01) for males and 1.25 (95% CI = 1.14-1.38, p < 0.01) for females. Case-control studies specifically showed an effect, but with marginal significance only (HR = 1.27, 95% CI = 0.98-1.65, p = 0.07). The Z-score plot indicated the need for additional analysis in the case-control group. A significant heterogeneity was observed across studies in all four settings. This meta-analysis provides robust evidence that obesity is a significant risk factor for colorectal cancer, with an overall hazard rate indicating a 36% increased risk. The effect is pronounced across both sexes, with males showing a slightly higher risk compared to females. Although case-control studies showed a weaker association, the overall trend supports the link between obesity and CRC. These results underscore the importance of public health interventions aimed at reducing obesity to potentially lower the risk of colorectal cancer.

Aryl hydrocarbon receptor (AhR)-mediated immune responses to degeneration of the retinal pigment epithelium

Injuries to the retinal pigment epithelium (RPE) trigger immune responses, orchestrating interactions within the innate and adaptive immune systems in the outer retina and choroid. We previously reported that interleukin 17 (IL-17) is a pivotal signaling molecule originating from choroidal γδ T cells, exerting protective effects by mediating functional connections between the RPE and subretinal microglia. In this current study, we generated mice with aryl hydrocarbon receptor (AhR) knockout specifically in IL-17-producing cells. These animals had deficiency in IL-17 production from γδ T cells, and exhibited increased sensitivity to both acute and chronic insults targeting the RPE. These findings imply that IL-17 plays a crucial role as a signaling cytokine in preserving the homeostasis of the outer retina and choroid.

PDK4-mediated Nrf2 inactivation contributes to oxidative stress and diabetic kidney injury

Diabetic kidney disease (DKD) is often featured with redox dyshomeostatis. Pyruvate dehydrogenase kinase 4 (PDK4) is the hub for DKD development. However, the mechanism by which PDK4 mediates DKD is poorly understood. The current work aimed to elucidate the relationship between PDK4 and DKD from the perspective of redox manipulation. Oxidative stress was observed in the human proximal tubular cell line (HK-2 cells) treated with a high concentration of glucose and palmitic acid (HGL). The mechanistic study showed that PDK4 could upregulate Kelch-like ECH-associated protein 1 (Keap1) in HGL-treated HK-2 cells through the suppression of autophagy, resulting in the depletion of nuclear factor erythroid 2-related factor 2 (Nrf2), the master regulator of redox homeostasis. At the cellular level, pharmacological inhibition or genetic knockdown of PDK4 could boost Nrf2, followed by the increase of a plethora of antioxidant enzymes and ferroptosis-suppression enzymes. Meanwhile, the inhibition or knockdown of PDK4 remodeled iron metabolism, further mitigating oxidative stress and lipid peroxidation. The same trend was observed in the DKD mice model. The current work highlighted the role of PDK4 in the development of DKD and suggested that PDK4 might be a promising target for the management of DKD.

Adipocyte-specific Nrf2 deletion negates nitro-oleic acid benefits on glucose tolerance in diet-induced obesity

Obesity is commonly linked with white adipose tissue (WAT) dysfunction, setting off inflammation and oxidative stress, both key contributors to the cardiometabolic complications associated with obesity. To improve metabolic and cardiovascular health, countering these inflammatory and oxidative signaling processes is crucial. Offering potential in this context, the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) by nitro-fatty acids (NO2-FA) promote diverse anti-inflammatory signaling and counteract oxidative stress. Additionally, we previously highlighted that nitro-oleic acid (NO2-OA) preferentially accumulates in WAT and provides protection against already established high fat diet (HFD)-mediated impaired glucose tolerance. The precise mechanism accounting for these protective effects remained largely unexplored until now. Herein, we reveal that protective effects of improved glucose tolerance by NO2-OA is absent when Nrf2 is specifically ablated in adipocytes (ANKO mice). NO2-OA treatment did not alter body weight between ANKO and littermate controls (Nrf2fl/fl) mice on both the HFD and low-fat diet (LFD). As expected, at day 76 (before NO2-OA treatment) and notably at day 125 (daily treatment of 15 mg/kg NO2-OA for 48 days), both HFD-fed Nrf2fl/fl and ANKO mice exhibited increased fat mass and reduced lean mass compared to LFD controls. However, throughout the NO2-OA treatment, no distinction was observed between Nrf2fl/fl and ANKO in the HFD-fed mice as well as in the Nrf2fl/fl mice fed a LFD. Glucose tolerance tests revealed impaired glucose tolerance in HFD-fed Nrf2fl/fl and ANKO compared to LFD-fed Nrf2fl/fl mice. Notably, NO2-OA treatment improved glucose tolerance in HFD-fed Nrf2fl/fl but did not yield the same improvement in ANKO mice at days 15, 30, and 55 of treatment. Unraveling the pathways linked to NO2-OA's protective effects in obesity-mediated impairment in glucose tolerance is pivotal within the realm of precision medicine, crucially propelling future applications and refining novel drug-based strategies.

Sex Differences Affect the NRF2 Signaling Pathway in the Early Phase of Liver Steatosis: A High-Fat-Diet-Fed Rat Model Supplemented with Liquid Fructose

Sex differences may play a role in the etiopathogenesis and severity of metabolic dysfunction-associated steatotic liver disease (MASLD), a disorder characterized by excessive fat accumulation associated with increased inflammation and oxidative stress. We previously observed the development of steatosis specifically in female rats fed a high-fat diet enriched with liquid fructose (HFHFr) for 12 weeks. The aim of this study was to better characterize the observed sex differences by focusing on the antioxidant and cytoprotective pathways related to the KEAP1/NRF2 axis. The KEAP1/NRF2 signaling pathway, autophagy process (LC3B and LAMP2), and endoplasmic reticulum stress response (XBP1) were analyzed in liver homogenates in male and female rats that were fed a 12-week HFHFr diet. In females, the HFHFr diet resulted in the initial activation of the KEAP1/NRF2 pathway, which was not followed by the modulation of downstream molecular targets; this was possibly due to the increase in KEAP1 levels preventing the nuclear translocation of NRF2 despite its cytosolic increase. Interestingly, while in both sexes the HFHFr diet resulted in an increase in the levels of LC3BII/LC3BI, a marker of autophagosome formation, only males showed a significant upregulation of LAMP2 and XBP1s; this did not occur in females, suggesting impaired autophagic flux in this sex. Overall, our results suggest that males are characterized by a greater ability to cope with an HFHFr metabolic stimulus mainly through an autophagic-mediated proteostatic process while in females, this is impaired. This might depend at least in part upon the fine modulation of the cytoprotective and antioxidant KEAP1/NRF2 pathway resulting in sex differences in the occurrence and severity of MASLD. These results should be considered to design effective therapeutics for MASLD.

Glutathione synthesis in the mouse liver supports lipid abundance through NRF2 repression

Cells rely on antioxidants to survive. The most abundant antioxidant is glutathione (GSH). The synthesis of GSH is non-redundantly controlled by the glutamate-cysteine ligase catalytic subunit (GCLC). GSH imbalance is implicated in many diseases, but the requirement for GSH in adult tissues is unclear. To interrogate this, we have developed a series of in vivo models to induce Gclc deletion in adult animals. We find that GSH is essential to lipid abundance in vivo. GSH levels are highest in liver tissue, which is also a hub for lipid production. While the loss of GSH does not cause liver failure, it decreases lipogenic enzyme expression, circulating triglyceride levels, and fat stores. Mechanistically, we find that GSH promotes lipid abundance by repressing NRF2, a transcription factor induced by oxidative stress. These studies identify GSH as a fulcrum in the liver's balance of redox buffering and triglyceride production.

NRF2-mediated regulation of lipid pathways in viral infection

The first line of defense against viral infection of the host cell is the cellular lipid membrane, which is also a crucial first site of contact for viruses. Lipids may sometimes be used as viral receptors by viruses. For effective infection, viruses significantly depend on lipid rafts during the majority of the viral life cycle. It has been discovered that different viruses employ different lipid raft modification methods for attachment, internalization, membrane fusion, genome replication, assembly, and release. To preserve cellular homeostasis, cells have potent antioxidant, detoxifying, and cytoprotective capabilities. Nuclear factor erythroid 2-related factor 2 (NRF2), widely expressed in many tissues and cell types, is one crucial component controlling electrophilic and oxidative stress (OS). NRF2 has recently been given novel tasks, including controlling inflammation and antiviral interferon (IFN) responses. The activation of NRF2 has two effects: it may both promote and prevent the development of viral diseases. NRF2 may also alter the host's metabolism and innate immunity during viral infection. However, its primary function in viral infections is to regulate reactive oxygen species (ROS). In several research, the impact of NRF2 on lipid metabolism has been examined. NRF2 is also involved in the control of lipids during viral infection. We evaluated NRF2's function in controlling viral and lipid infections in this research. We also looked at how lipids function in viral infections. Finally, we investigated the role of NRF2 in lipid modulation during viral infections.

Expression profile of viability and stress response genes as a result of resveratrol supplementation in vitrified and in vitro produced cattle embryos

BACKGROUND

Resveratrol, a potent antioxidant, is known to induce the up-regulation of the internal antioxidant system. Therefore, it holds promise as a method to mitigate cryopreservation-induced injuries in bovine oocytes and embryos. This study aimed to (i) assess the enhancement in the quality of in vitro produced bovine embryos following resveratrol supplementation and (ii) monitor changes in the expression of genes associated with oxidative stress (GPX4, SOD, CPT2, NFE2L2), mitochondrial function (ATP5ME), endoplasmic reticulum function (ATF6), and embryo quality (OCT4, DNMT1, CASP3, ELOVL5).

METHODS AND RESULTS

Three groups of in vitro bovine embryos were cultured with varying concentrations of resveratrol (0.01, 0.001, and 0.0001 µM), with a fourth group serving as a control. Following the vitrification process, embryos were categorized as either good or poor quality. Blastocysts were then preserved at - 80 °C for RNA isolation, followed by qRT-PCR analysis of selected genes. The low concentrations of resveratrol (0.001 µM, P < 0.05 and 0.0001 µM, P < 0.01) significantly improved the blastocyst rate compared to the control group. Moreover, the proportion of good quality vitrified embryos increased significantly (P < 0.05) in the groups treated with 0.001 and 0.0001 µM resveratrol compared to the control group. Analysis of gene expression showed a significant increase in OCT4 and DNMT1 transcripts in both good and poor-quality embryos treated with resveratrol compared to untreated embryos. Additionally, CASP3 expression was decreased in treated good embryos compared to control embryos. Furthermore, ELOVL5 and ATF6 transcripts were down-regulated in treated good embryos compared to the control group. Regarding antioxidant-related genes, GPX4, SOD, and CPT2 transcripts increased in the treated embryos, while NFE2L2 mRNA decreased in treated good embryos compared to the control group.

CONCLUSIONS

Resveratrol supplementation at low concentrations effectively mitigated oxidative stress and enhanced the cryotolerance of embryos by modulating the expression of genes involved in oxidative stress response.

Plastoquinone-Derivative SkQ1 Improved the Biliary Intraepithelial Neoplasia during Liver Fluke Infection

Carcinogenic food-borne liver fluke infections are a serious epidemiological threat worldwide. The major complications of Opisthorchis felineus infection are chronic inflammation and biliary intraepithelial neoplasia. Although evidence has accumulated that increased reactive oxygen species production is observed in liver fluke infection, a direct relationship between the oxidative stress and biliary intraepithelial neoplasia has not been shown. Quinones and SkQ1, a derivative of plastoquinone, have been demonstrated to be cytoprotective in numerous liver injuries due to their potent antioxidant properties. This study is aimed to assess the level of biliary intraepithelial neoplasia in O. felineus-infected hamsters after treatment with mitochondria-targeted SkQ1. SkQ1 significantly reduced the biliary intraepithelial neoplasia, which was accompanied by a decrease in lipid and DNA oxidation byproducts, mRNA expression and level of proteins associated with inflammation (TNF-α, CD68) and fibrogenesis (CK7, αSMA), and was also associated with an activation of the Keap1-Nrf2 pathway. Thus, a direct relationship was found between oxidative stress and the severity of biliary intraepithelial neoplasia in O. felineus-infected hamsters. The hepatoprotective effect of plastoquinone-derivative SkQ1 was established; therefore, this compound is a promising agent in complex therapy in the treatment of opisthorchiasis.

Distinct bile acid alterations in response to a single administration of PFOA and PFDA in mice

Per- and polyfluoroalkyl substances (PFASs), a group of synthetic chemicals that were once widely used for industrial purposes and in consumer products, are widely found in the environment and in human blood due to their extraordinary resistance to degradation. Once inside the body, PFASs can activate nuclear receptors such as PPARα and CAR. The present study aimed to investigate the impact of perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA) on liver structure and functions, as well as bile acid homeostasis in mice. A single administration of 0.1 mmole/kg of PFDA, not PFOA, elevated serum ALT and bilirubin levels and caused cholestasis in WT mice. PFDA increased total and various bile acid species in serum but decreased them in the liver. Furthermore, in mouse livers, PFDA, not PFOA, down-regulated mRNA expression of uptake transporters (Ntcp, Oatp1a1, 1a4, 1b2, and 2b1) but induced efflux transporters (Bcrp, Mdr2, and Mrp2-4). In addition, PFDA, not PFOA, decreased Cyp7a1, 7b1, 8b1, and 27a1 mRNA expression in mouse livers with concomitant hepatic accumulation of cholesterol. In contrast, in PPARα-null mice, PFDA did not increase serum ALT, bilirubin, or total bile acids, but produced prominent hepatosteatosis; and the observed PFDA-induced expression changes of transporters and Cyps in WT mice were largely attenuated or abolished. In CAR-null mice, the observed PFDA-induced bile acid alterations in WT mice were mostly sustained. These results indicate that, at the dose employed, PFDA has more negative effects than PFOA on liver function. PPARα appears to play a major role in mediating most of PFDA-induced effects, which were absent or attenuated in PPARα-null mice. Lack of PPARα, however, exacerbated hepatic steatosis. Our findings indicate separated roles of PPARα in mediating the adaptive responses to PFDA: protective against hepatosteatosis but exacerbating cholestasis.

Specific targeting of the NRF2/β-TrCP axis promotes beneficial effects in NASH

Non-alcoholic steatohepatitis (NASH) is a common chronic liver disease that compromises liver function, for which there is not a specifically approved medicine. Recent research has identified transcription factor NRF2 as a potential therapeutic target. However, current NRF2 activators, designed to inhibit its repressor KEAP1, exhibit unwanted side effects. Alternatively, we previously introduced PHAR, a protein-protein interaction inhibitor of NRF2/β-TrCP, which induces a mild NRF2 activation and selectively activates NRF2 in the liver, close to normal physiological levels. Herein, we assessed the effect of PHAR in protection against NASH and its progression to fibrosis. We conducted experiments to demonstrate that PHAR effectively activated NRF2 in hepatocytes, Kupffer cells, and stellate cells. Then, we used the STAM mouse model of NASH, based on partial damage of endocrine pancreas and insulin secretion impairment, followed by a high fat diet. Non-invasive analysis using MRI revealed that PHAR protects against liver fat accumulation. Moreover, PHAR attenuated key markers of NASH progression, including liver steatosis, hepatocellular ballooning, inflammation, and fibrosis. Notably, transcriptomic data indicate that PHAR led to upregulation of 3 anti-fibrotic genes (Plg, Serpina1a, and Bmp7) and downregulation of 6 pro-fibrotic (including Acta2 and Col3a1), 11 extracellular matrix remodeling, and 8 inflammatory genes. Overall, our study suggests that the mild activation of NRF2 via the protein-protein interaction inhibitor PHAR holds promise as a strategy for addressing NASH and its progression to liver fibrosis.

Mitochondria- and NOX4-dependent antioxidant defense mitigates progression to nonalcoholic steatohepatitis in obesity

Nonalcoholic fatty liver disease (NAFLD) is prevalent in the majority of individuals with obesity, but in a subset of these individuals, it progresses to nonalcoholic steatohepatitis (0NASH) and fibrosis. The mechanisms that prevent NASH and fibrosis in the majority of patients with NAFLD remain unclear. Here, we report that NAD(P)H oxidase 4 (NOX4) and nuclear factor erythroid 2-related factor 2 (NFE2L2) were elevated in hepatocytes early in disease progression to prevent NASH and fibrosis. Mitochondria-derived ROS activated NFE2L2 to induce the expression of NOX4, which in turn generated H2O2 to exacerbate the NFE2L2 antioxidant defense response. The deletion or inhibition of NOX4 in hepatocytes decreased ROS and attenuated antioxidant defense to promote mitochondrial oxidative stress, damage proteins and lipids, diminish insulin signaling, and promote cell death upon oxidant challenge. Hepatocyte NOX4 deletion in high-fat diet-fed obese mice, which otherwise develop steatosis, but not NASH, resulted in hepatic oxidative damage, inflammation, and T cell recruitment to drive NASH and fibrosis, whereas NOX4 overexpression tempered the development of NASH and fibrosis in mice fed a NASH-promoting diet. Thus, mitochondria- and NOX4-derived ROS function in concert to drive a NFE2L2 antioxidant defense response to attenuate oxidative liver damage and progression to NASH and fibrosis in obesity.

Mitochondrial Reactive Oxygen Species, Insulin Resistance, and Nrf2-Mediated Oxidative Stress Response-Toward an Actionable Strategy for Anti-Aging

Reactive oxygen species (ROS) are produced mainly by mitochondrial respiration and function as signaling molecules in the physiological range. However, ROS production is also associated with the pathogenesis of various diseases, including insulin resistance (IR) and type 2 diabetes (T2D). This review focuses on the etiology of IR and early events, especially mitochondrial ROS (mtROS) production in insulin-sensitive tissues. Importantly, IR and/or defective adipogenesis in the white adipose tissues (WAT) is thought to increase free fatty acid and ectopic lipid deposition to develop into systemic IR. Fatty acid and ceramide accumulation mediate coenzyme Q reduction and mtROS production in IR in the skeletal muscle, while coenzyme Q synthesis downregulation is also involved in mtROS production in the WAT. Obesity-related IR is associated with the downregulation of mitochondrial catabolism of branched-chain amino acids (BCAAs) in the WAT, and the accumulation of BCAA and its metabolites as biomarkers in the blood could reliably indicate future T2D. Transcription factor NF-E2-related factor 2 (Nrf2), which regulates antioxidant enzyme expression in response to oxidative stress, is downregulated in insulin-resistant tissues. However, Nrf2 inducers, such as sulforaphane, could restore Nrf2 and target gene expression and attenuate IR in multiple tissues, including the WAT.

A new NRF2 activator for the treatment of human metabolic dysfunction-associated fatty liver disease

Background & Aims

Oxidative stress triggers metabolic-associated fatty liver disease (MAFLD) and fibrosis. Previous animal studies demonstrated that the transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2), the master regulator of antioxidant response, protects against MAFLD and fibrosis. S217879, a next generation NRF2 activator has been recently shown to trigger diet-induced steatohepatitis resolution and to reduce established fibrosis in rodents. Our aim was to evaluate the therapeutic potential of S217879 in human MAFLD and its underlying mechanisms using the relevant experimental 3D model of patient-derived precision cut liver slices (PCLS).

Methods

We treated PCLS from 12 patients with varying stages of MAFLD with S217879 or elafibranor (peroxisome proliferator-activated receptor [PPAR]α/δ agonist used as a referent molecule) for 2 days. Safety and efficacy profiles, steatosis, liver injury, inflammation, and fibrosis were assessed as well as mechanisms involved in MAFLD pathophysiology, namely antioxidant response, autophagy, and endoplasmic reticulum-stress.

Results

Neither elafibranor nor S217879 had toxic effects at the tested concentrations on human PCLS with MAFLD. PPARα/δ and NRF2 target genes (pyruvate dehydrogenase kinase 4 [PDK4], fibroblast growth factor 21 [FGF21], and NAD(P)H quinone dehydrogenase 1 [NQO1], heme oxygenase 1 [HMOX1], respectively) were strongly upregulated in PCLS in response to elafibranor and S217879, respectively. Compared with untreated PCLS, elafibranor and S217879-treated slices displayed lower triglycerides and reduced inflammation (IL-1β, IL-6, chemokine (C-C motif) ligand 2 [CCL2]). Additional inflammatory markers (chemokine (C-C motif) ligand 5 [CCL5], stimulator of interferon genes [STING], intercellular adhesion molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1]) were downregulated by S217879. S217879 but not elafibranor lowered DNA damage (phospho-Histone H2A.X [p-H2A.X], RAD51, X-ray repair cross complementing 1 [XRCC1]) and apoptosis (cleaved caspase-3), and inhibited fibrogenesis markers expression (alpha smooth muscle actin [α-SMA], collagen 1 alpha 1 [COL1A1], collagen 1 alpha 2 [COL1A2]). Such effects were mediated through an improvement of lipid metabolism, activated antioxidant response and enhanced autophagy, without effect on endoplasmic reticulum-stress.

Conclusions

This study highlights the therapeutic potential of a new NRF2 activator for MAFLD using patient-derived PCLS supporting the evaluation of NRF2 activating strategies in clinical trials.

Impact and implications

Oxidative stress is a major driver of metabolic-associated fatty liver disease (MAFLD) development and progression. Nuclear factor (erythroid-derived 2)-like 2, the master regulator of the antioxidative stress response, is an attractive therapeutic target for the treatment of MAFLD. This study demonstrates that S217879, a new potent and selective nuclear factor (erythroid-derived 2)-like 2 activator, displays antisteatotic effects, lowers DNA damage, apoptosis, and inflammation and inhibits fibrogenesis in human PCLS in patients with MAFLD.

Tauroursodeoxycholic Acid Supplementation in In Vitro Culture of Indicine Bovine Embryos: Molecular and Cellular Effects on the In Vitro Cryotolerance

During embryo development, the endoplasmic reticulum (ER) acts as an important site for protein biosynthesis; however, in vitro culture (IVC) can negatively affect ER homeostasis. Therefore, the aim of our study was to evaluate the effects of the supplementation of tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor, in the IVC of bovine embryos. Two experiments were carried out: Exp. 1: an evaluation of blastocyst rate, hatching kinetics, and gene expression of hatched embryos after being treated with different concentrations of TUDCA (50, 200, or 1000 μM) in the IVC; Exp. 2: an evaluation of the re-expansion, hatching, and gene expression of hatched embryos previously treated with 200 µM of TUDCA at IVC and submitted to vitrification. There was no increase in the blastocyst and hatched blastocyst rates treated with TUDCA in the IVC. However, embryos submitted to vitrification after treatment with 200 µM of TUDCA underwent an increased hatching rate post-warming together with a down-regulation in the expression of ER stress-related genes and the accumulation of lipids. In conclusion, this work showed that the addition of TUDCA during in vitro culture can improve the cryotolerance of the bovine blastocyst through the putative modulation of ER and oxidative stress.

Gene network based analysis identifies a coexpression module involved in regulating plasma lipids with high-fat diet response

Plasma lipids are modulated by gene variants and many environmental factors, including diet-associated weight gain. However, understanding how these factors jointly interact to influence molecular networks that regulate plasma lipid levels is limited. Here, we took advantage of the BXD recombinant inbred family of mice to query weight gain as an environmental stressor on plasma lipids. Coexpression networks were examined in both nonobese and obese livers, and a network was identified that specifically responded to the obesogenic diet. This obesity-associated module was significantly associated with plasma lipid levels and enriched with genes known to have functions related to inflammation and lipid homeostasis. We identified key drivers of the module, including Cidec, Cidea, Pparg, Cd36, and Apoa4. The Pparg emerged as a potential master regulator of the module as it can directly target 19 of the top 30 hub genes. Importantly, activation of this module is causally linked to lipid metabolism in humans, as illustrated by correlation analysis and inverse-variance weighed Mendelian randomization. Our findings provide novel insights into gene-by-environment interactions for plasma lipid metabolism that may ultimately contribute to new biomarkers, better diagnostics, and improved approaches to prevent or treat dyslipidemia in patients.

Astrocyte-oligodendrocyte interaction regulates central nervous system regeneration

Failed regeneration of myelin around neuronal axons following central nervous system damage contributes to nerve dysfunction and clinical decline in various neurological conditions, for which there is an unmet therapeutic demand. Here, we show that interaction between glial cells - astrocytes and mature myelin-forming oligodendrocytes - is a determinant of remyelination. Using in vivo/ ex vivo/ in vitro rodent models, unbiased RNA sequencing, functional manipulation, and human brain lesion analyses, we discover that astrocytes support the survival of regenerating oligodendrocytes, via downregulation of the Nrf2 pathway associated with increased astrocytic cholesterol biosynthesis pathway activation. Remyelination fails following sustained astrocytic Nrf2 activation in focally-lesioned male mice yet is restored by either cholesterol biosynthesis/efflux stimulation, or Nrf2 inhibition using the existing therapeutic Luteolin. We identify that astrocyte-oligodendrocyte interaction regulates remyelination, and reveal a drug strategy for central nervous system regeneration centred on targeting this interaction.

Phloretamide Prevent Hepatic and Pancreatic Damage in Diabetic Male Rats by Modulating Nrf2 and NF-κB

This study examined the effect of phloretamide, a metabolite of phloretin, on liver damage and steatosis in streptozotocin-induced diabetes mellitus (DM) in rats. Adult male rats were divided into two groups: control (nondiabetic) and STZ-treated rats, each of which was further treated orally with the vehicle phloretamide 100 mg or 200 mg. Treatments were conducted for 12 weeks. Phloretamide, at both doses, significantly attenuated STZ-mediated pancreatic β-cell damage, reduced fasting glucose, and stimulated fasting insulin levels in STZ-treated rats. It also increased the levels of hexokinase, which coincided with a significant reduction in glucose-6 phosphatase (G-6-Pase), and fructose-1,6-bisphosphatase 1 (PBP1) in the livers of these diabetic rats. Concomitantly, both doses of phloretamide reduced hepatic and serum levels of triglycerides (TGs) and cholesterol (CHOL), serum levels of low-density lipoprotein cholesterol (LDL-c), and hepatic ballooning. Furthermore, they reduced levels of lipid peroxidation, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), mRNA, and total and nuclear levels of NF-κB p65, but increased mRNA levels, total and nuclear levels of Nrf2, as well as levels of reduced glutathione (GSH), superoxide dismutase (SOD-1), catalase (CAT), and heme-oxygenase-1 (HO-1) in the livers of diabetic rats. All of these effects were dose-dependent. In conclusion, phloretamide is a novel drug that could ameliorate DM-associated hepatic steatosis via its powerful antioxidant and anti-inflammatory effects. Mechanisms of protection involve improving the β-cell structure and hepatic insulin action, suppressing hepatic NF-κB, and stimulating hepatic Nrf2.

Selective disruption of NRF2-KEAP1 interaction leads to NASH resolution and reduction of liver fibrosis in mice

Background & Aims

Oxidative stress is recognized as a major driver of non-alcoholic steatohepatitis (NASH) progression. The transcription factor NRF2 and its negative regulator KEAP1 are master regulators of redox, metabolic and protein homeostasis, as well as detoxification, and thus appear to be attractive targets for the treatment of NASH.

Methods

Molecular modeling and X-ray crystallography were used to design S217879 - a small molecule that could disrupt the KEAP1-NRF2 interaction. S217879 was highly characterized using various molecular and cellular assays. It was then evaluated in two different NASH-relevant preclinical models, namely the methionine and choline-deficient diet (MCDD) and diet-induced obesity NASH (DIO NASH) models.

Results

Molecular and cell-based assays confirmed that S217879 is a highly potent and selective NRF2 activator with marked anti-inflammatory properties, as shown in primary human peripheral blood mononuclear cells. In MCDD mice, S217879 treatment for 2 weeks led to a dose-dependent reduction in NAFLD activity score while significantly increasing liver Nqo1 mRNA levels, a specific NRF2 target engagement biomarker. In DIO NASH mice, S217879 treatment resulted in a significant improvement of established liver injury, with a clear reduction in both NAS and liver fibrosis. αSMA and Col1A1 staining, as well as quantification of liver hydroxyproline levels, confirmed the reduction in liver fibrosis in response to S217879. RNA-sequencing analyses revealed major alterations in the liver transcriptome in response to S217879, with activation of NRF2-dependent gene transcription and marked inhibition of key signaling pathways that drive disease progression.

Conclusions

These results highlight the potential of selective disruption of the NRF2-KEAP1 interaction for the treatment of NASH and liver fibrosis.

Impact and implications

We report the discovery of S217879 - a potent and selective NRF2 activator with good pharmacokinetic properties. By disrupting the KEAP1-NRF2 interaction, S217879 triggers the upregulation of the antioxidant response and the coordinated regulation of a wide spectrum of genes involved in NASH disease progression, leading ultimately to the reduction of both NASH and liver fibrosis progression in mice.

Spirulina platensis Ameliorates Oxidative Stress Associated with Antiretroviral Drugs in HepG2 Cells

Lately, Spirulina platensis (SP), as an antioxidant, has exhibited high potency in the treatment of oxidative stress, diabetes, immune disorder, inflammatory stress, and bacterial and viral-related diseases. This study investigated the possible protective role of Spirulina platensis against ARV-induced oxidative stress in HepG2 cells. Human liver (HepG2) cells were treated with ARVs ((Lamivudine (3TC): 1.51 µg/mL, tenofovir disoproxil fumarate (TDF): 0.3 µg/mL and Emtricitabine (FTC): 1.8 µg/mL)) for 96 h and thereafter treated with 1.5 µg/mL Spirulina platensis for 24 h. After the treatments, the gene and protein expressions of the antioxidant response pathway were determined using a quantitative polymerase chain reaction (qPCR) and Western blots. The results show that Spirulina platensis decreased the gene expressions of Akt (p < 0.0001) and eNOS (↓p < 0.0001) while, on the contrary, it increased the transcript levels of NRF-2 (↑p = 0.0021), Keap1 (↑p = 0.0002), CAT (↑p < 0.0001), and NQO-1 (↑p = 0.1432) in the HepG2 cells. Furthermore, the results show that Spirulina platensis also decreased the protein expressions of NRF-2 (↓p = 0.1226) and pNRF-2 (↓p = 0.0203). Interestingly, HAART-SP induced an NRF-2 pathway response through upregulating NRF-2 (except for FTC-SP) (↑p < 0.0001), CAT (↑p < 0.0001), and NQO-1 (except for FTC-SP) (↑p < 0.0001) mRNA expression. In addition, NRF-2 (↑p = 0.0085) and pNRF-2 (↑p < 0.0001) protein expression was upregulated in the HepG2 cells post-exposure to HAART-SP. The results, therefore, allude to the fact that Spirulina platensis has the potential to mitigate HAART-adverse drug reactions (HAART toxicity) through the activation of antioxidant response in HepG2 cells. We hereby recommend further studies on Spirulina platensis and HAART synergy.

Exosomes derived from human umbilical cord mesenchymal stem cells ameliorate experimental non-alcoholic steatohepatitis via Nrf2/NQO-1 pathway

BACKGROUND

No approved effective therapy for non-alcoholic steatohepatitis (NASH) is currently available. Exosomes derived from mesenchymal stem cells (MSCs) perform the functions such as inhibiting inflammation, anti-oxidative stress, regulating immunity, but it is not clear whether human umbilical cord mesenchymal stem cells (hUC-MSCs) exosomes protect against NASH through Nrf2/NQO-1 pathway. Therefore, this study was conducted to investigate the effects of hUC-MSCs exosomes on NASH through Nrf2/NQO-1 pathway in vivo and in vitro.

METHODS

C57BL/6J male mice were fed with high fat and high cholesterol diet (HFHC) and methionine choline deficiency diet (MCD). Mice were treated with or without hUC-MSCs exosomes by tail intravenous injection. The liver histology, lipid metabolism and oxidative stress were evaluated. HepG2 and AML12 cells were incubated with palmitic acid (PA) and MCD conditioned medium, respectively. Then the therapeutic effect of hUC-MSCs exosomes in steatotic cells was evaluated. To elucidate the signaling pathways, the Nrf2-specific blocker ML385 was applied to intervene in vitro.

RESULTS

In NASH models, hUC-MSCs exosomes attenuated steatosis in hepatocytes, altered the abnormal expression of lipid-related genes including SREBP-1c, PPAR-α, Fabp5, CPT1α, ACOX and FAS, suppressed the hepatic inflammatory responses by decreasing the expression of F4/80+ macrophages, CD11c+ macrophages as well as the content of TNF-α and IL-6. hUC-MSCs exosomes also inhibited oxidative stress by reducing the level of MDA, CYP2E1 and ROS, increasing the activity of SOD and GSH in hepatocytes. Notably, hUC-MSCs exosomes enhanced the protein ratio of p-Nrf2/Nrf2 and the protein expression of NQO-1. Moreover, in vitro, the therapeutic effects of hUC-MSCs exosomes on lipid deposition and ROS were reversed by ML385. Also, ML385 reduced the protein expression of p-Nrf2 and NQO-1 in vitro.

CONCLUSION

Nrf2/NQO-1 antioxidant signaling pathway may play a key role in the treatment of NASH by hUC-MSCs exosomes.

The Nrf2 in Obesity: A Friend or Foe?

Obesity and its complications have become serious global health concerns recently and increasing work has been carried out to explicate the underlying mechanism of the disease development. The recognized correlations suggest oxidative stress and inflammation in expanding adipose tissue with excessive fat accumulation play important roles in the pathogenesis of obesity, as well as its associated metabolic syndromes. In adipose tissue, obesity-mediated insulin resistance strongly correlates with increased oxidative stress and inflammation. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been described as a key modulator of antioxidant signaling, which regulates the transcription of various genes coding antioxidant enzymes and cytoprotective proteins. Furthermore, an increasing number of studies have demonstrated that Nrf2 is a pivotal target of obesity and its related metabolic disorders. However, its effects are controversial and even contradictory. This review aims to clarify the complicated interplay among Nrf2, oxidative stress, lipid metabolism, insulin signaling and chronic inflammation in obesity. Elucidating the implications of Nrf2 modulation on obesity would provide novel insights for potential therapeutic approaches in obesity and its comorbidities.

Jia-ga-song-tang protection against alcoholic liver and intestinal damage

Gut-liver axis and cellular homeostasis play key roles in alcohol liver disease (ALD). Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a stress-sensitive guarantor of cellular homeostasis. We investigated whether the beneficial effects and underlying mechanisms of Jia-ga-song Tang (JGST) against ALD were associated with gut-liver axis and cellular homeostasis. A predictive network depicting the relationship between Jia-Ga-Song-Tang (JGST) and alcoholic liver disease (ALD) was designed by Network pharmacology. Next, 5% v/v Lieber-DeCarli alcohol liquid diet was used to establish the ALD. JGST protected the liver damage, repaired the intestines to alleviate the Two-hit on the liver, and balanced the cellular homeostasis. It was manifested in repairing the liver and intestinal pathological structure, reducing serum ALT, AST, and liver TG, TC, MDA, CAT, and increasing liver GSH, and intestine GSH-Px. JGST mainly inhibited the liver mRNA levels of HO-1, NQO1, GCLC, FASN, and PPARα and activated the intestinal mRNA levels of HO-1 and NQO1, while inhibiting the liver protein levels of HO-1, NQO1. Furthermore, LPS and LBP in the plasma and the expression of inflammatory factors such as IL-1β, TNF-α, IL-6, TGFβ1, CD14, and Myd88 were reduced after treatment to prove that JGST protects the liver from Two-hit. Ethanol was used to intervene in HepG2 and IEC-6 to establish an ALD cell model and treated by Germacrone, ML385, and TBHQ. repaired the intestinal barrier, and inhibited Nrf2 in IEC-6, but protect the HepG2 by activating Nrf2 to balance cellular homeostasis. Our results reinforce that JGST provides an effective protective method for alcoholic liver disease (ALD) by regulating Gut-liver axis and cellular homeostasis.

Metabolic Syndrome Ameliorated by 4-Methylesculetin by Reducing Hepatic Lipid Accumulation

Obesity is a chronic metabolic disease caused by an imbalance between energy intake and expenditure during a long period and is characterized by adipose tissue disfunction and hepatic steatosis. The aim of this study was to investigate the effect of 4-methylesculetin (4-ME), a coumarin derivative, upon adipose microenvironment and hepatic steatosis in mice induced by a high-fat diet (HFD), and to explore potential mechanisms of its beneficial effect on metabolic disorders. HFD-fed mice displayed visceral obesity, insulin resistance, and hepatic lipid accumulation, which was remarkably ameliorated by 4-ME treatment. Meanwhile, 4-ME ameliorated adipocyte hypertrophy, macrophage infiltration, hypoxia, and fibrosis in epididymal adipose tissue, thus improving the adipose tissue microenvironment. Furthermore, 4-ME reversed the increase in CD36, PPAR-γ, SREBP-1, and FASN, and the decrease in CPT-1A, PPAR-α, and Nrf2 translocation into the nucleus in livers of HFD mice and in FFA-incubated hepatocytes. Moreover, the beneficial effects of 4-ME upon lipid deposition and the expression of proteins related to lipid metabolism in FFA-induced LO2 cells were abolished by ML385, a specific Nrf2 inhibitor, indicating that Nrf2 is necessary for 4-ME to reduce hepatic lipid deposition. These findings suggested that 4-ME might be a potential lead compound candidate for preventing obesity and MAFLD.

AMPK and NRF2: Interactive players in the same team for cellular homeostasis?

NRF2 (Nuclear factor E2 p45-related factor 2) is a stress responsive transcription factor lending cells resilience against oxidative, xenobiotic, and also nutrient or proteotoxic insults. AMPK (AMP-activated kinase), considered as prime regulator of cellular energy homeostasis, not only tunes metabolism to provide the cell at any time with sufficient ATP or building blocks, but also controls redox balance and inflammation. Due to observed overlapping cellular responses upon AMPK or NRF2 activation and common stressors impinging on both AMPK and NRF2 signaling, it is plausible to assume that AMPK and NRF2 signaling may interdepend and cooperate to readjust cellular homeostasis. After a short introduction of the two players this narrative review paints the current picture on how AMPK and NRF2 signaling might interact on the molecular level, and highlights their possible crosstalk in selected examples of pathophysiology or bioactivity of drugs and phytochemicals.

The Structure Basis of Phytochemicals as Metabolic Signals for Combating Obesity

The consumption of phytochemicals, bioactive compounds in fruits and vegetables, has been demonstrated to ameliorate obesity and related metabolic symptoms by regulating specific metabolic pathways. This review summarizes the progress made in our understanding of the potential of phytochemicals as metabolic signals: we discuss herein selected molecular mechanisms which are involved in the occurrence of obesity that may be regulated by phytochemicals. The focus of our review highlights the regulation of transcription factors toll like receptor 4 (TLR4), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), the peroxisome proliferator-activated receptors (PPARs), fat mass and obesity-associated protein (FTO) and regulation of microRNAs (miRNA). In this review, the effect of phytochemicals on signaling pathways involved in obesity were discussed on the basis of their chemical structure, suggesting molecular mechanisms for how phytochemicals may impact these signaling pathways. For example, compounds with an isothiocyanate group or an α, β-unsaturated carbonyl group may interact with the TLR4 signaling pathway. Regarding Nrf2, we examine compounds possessing an α, β-unsaturated carbonyl group which binds covalently with the cysteine thiols of Keap1. Additionally, phytochemical activation of PPARs, FTO and miRNAs were summarized. This information may be of value to better understand how specific phytochemicals interact with specific signaling pathways and help guide the development of new drugs to combat obesity and related metabolic diseases.

Evolutionarily conserved transcription factors as regulators of longevity and targets for geroprotection

Aging is the single largest risk factor for many debilitating conditions, including heart diseases, stroke, cancer, diabetes, and neurodegenerative disorders. While far from understood in its full complexity, it is scientifically well-established that aging is influenced by genetic and environmental factors, and can be modulated by various interventions. One of aging's early hallmarks are aberrations in transcriptional networks, controlling for example metabolic homeostasis or the response to stress. Evidence in different model organisms abounds that a number of evolutionarily conserved transcription factors, which control such networks, can affect lifespan and healthspan across species. These transcription factors thus potentially represent conserved regulators of longevity and are emerging as important targets in the challenging quest to develop treatments to mitigate age-related diseases, and possibly even to slow aging itself. This review provides an overview of evolutionarily conserved transcription factors that impact longevity or age-related diseases in at least one multicellular model organism (nematodes, flies, or mice), and/or are tentatively linked to human aging. Discussed is the general evidence for transcriptional regulation of aging and disease, followed by a more detailed look at selected transcription factor families, the common metabolic pathways involved, and the targeting of transcription factors as a strategy for geroprotective interventions.

Tandem Mass Tagging-Based Quantitative Proteomics Analysis Reveals Damage to the Liver and Brain of Hypophthalmichthys molitrix Exposed to Acute Hypoxia and Reoxygenation

Aquaculture environments frequently experience hypoxia and subsequent reoxygenation conditions, which have significant effects on hypoxia-sensitive fish populations. In this study, hepatic biochemical activity indices in serum and the content of major neurotransmitters in the brain were altered markedly after acute hypoxia and reoxygenation exposure in silver carp (Hypophthalmichthys molitrix). Proteomics analysis of the liver showed that a number of immune-related and cytoskeletal organization-related proteins were downregulated, the ferroptosis pathway was activated, and several antioxidant molecules and detoxifying enzymes were upregulated. Proteomics analysis of the brain showed that somatostatin-1A (SST1A) was upregulated, dopamine-degrading enzyme catechol O methyltransferase (COMT) and ferritin, heavy subunit (FerH) were downregulated, and the levels of proteins involved in the nervous system were changed in different ways. In conclusion, these findings highlight that hypoxia–reoxygenation has potential adverse effects on growth, locomotion, immunity, and reproduction of silver carp, and represents a serious threat to liver and brain function, possibly via ferroptosis, oxidative stress, and cytoskeleton destruction in the liver, and abnormal expression of susceptibility genes for neurodegenerative disorders in the brain. Our present findings provide clues to the mechanisms of hypoxia and reoxygenation damage in the brain and liver of hypoxia-sensitive fish. They could also be used to develop methods to reduce hypoxia or reoxygenation injury to fish.

Genetically modified rabbit models for cardiovascular medicine

Genetically modified (GM) rabbits are outstanding animal models for studying human genetic and acquired diseases. As such, GM rabbits that express human genes have been extensively used as models of cardiovascular disease. Rabbits are genetically modified via prokaryotic microinjection. Through this process, genes are randomly integrated into the rabbit genome. Moreover, gene targeting in embryonic stem (ES) cells is a powerful tool for understanding gene function. However, rabbits lack stable ES cell lines. Therefore, ES-dependent gene targeting is not possible in rabbits. Nevertheless, the RNA interference technique is rapidly becoming a useful experimental tool that enables researchers to knock down specific gene expression, which leads to the genetic modification of rabbits. Recently, with the emergence of new genetic technology, such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), clustered regularly interspaced short palindromic repeats (CRISPR), and CRISPR-associated protein 9 (CRISPR/Cas9), major breakthroughs have been made in rabbit gene targeting. Using these novel genetic techniques, researchers have successfully modified knockout (KO) rabbit models. In this paper, we aimed to review the recent advances in GM technology in rabbits and highlight their application as models for cardiovascular medicine.

The influence of gastric bypass surgery on the concentration of high mobility group box 1, nuclear factor erythroid 2-related factor 2 and the genes expression of high mobility group box 1, nuclear factor erythroid2-related factor 2, interleukin 6, and tumor necrosis factor-alpha in the peripheral blood mononuclear cells of patients with morbid obesity

BACKGROUND AND OBJECTIVES

Obesity is known as a disease with a chronic low-grade state of inflammation and high levels of oxidative stress. Given the challenges and consequences caused by obesity, obesity therapy is an essential subject to address. For sustainable weight loss, gastric bypass surgery is the most successful and essential option.

METHODS

This prospective cohort study was performed on 35 patients aged (18-54) with morbid obesity (BMI: 42.06 kg/m²). Volunteers blood was taken, and peripheral blood mononuclear cells (PBMCs) were isolated, high mobility group box 1(HMGB1), nuclear factor erythroid2-related factor 2(Nrf2), Interleukin 6(IL-6), tumor necrosis factor-alpha (TNF-α), and biochemical factors were determined one day before and 4 months after surgery.

RESULTS

Four months following surgery, the BMI, hip and waist circumferences, and waist-to-hip ratio (WHR) all decreased significantly. The lipid profile and antioxidant power were dramatically enhanced after surgery. IL-6 and TNF-α expression in PBMC patients showed a significant decrease after surgery. HMGB1 and Nrf2 expression in PBMC of postoperative patients decreased compared to before surgery, and HMGB1, and Nrf2 protein levels also decreased after surgery.

CONCLUSION

Weight loss indicated the significant function of adipose tissue in the induction of oxidative stress and inflammatory factors. Gastric bypass reduced the inflammation conditions and improved the metabolic status and living situations in the patients with morbid obesity.

The myocardial infarction-associated transcript 2 inhibits lipid accumulation and promotes cholesterol efflux in oxidized low-density lipoprotein-induced THP-1-derived macrophages via inhibiting mitogen-activated protein kinase signaling and activating the nuclear factor erythroid-related factor 2 signaling pathway

Dysregulated lipid metabolism of macrophages contributes to thrombosis and antiphospholipid syndrome (APS). The long non-coding RNAs (lncRNA) myocardial infarction-associated transcript 2 (Mirt2) has been reported to inhibit inflammation and lipid accumulation; therefore, this study intended to clarify whether Mirt2 served a role in lipid metabolism. THP-1-derived macrophages with or without Mirt2-knockdown or overexpression, were exposed to oxidized low-density lipoprotein (ox-LDL), then cell migration, lipid accumulation, cholesterol efflux and inflammation were assessed using wound healing, oil red staining, commercial kits and western blot assays. Besides, ML385 was used to treat THP-1-derived macrophages to inhibit nuclear factor erythroid-related factor 2 (NRF2) expression. The expression of proteins involved in the above processes were measured by western blot. Results demonstrated that phorbol 12-myristate 13-acetate (PMA) significantly increased Mirt2 expression in THP-1 cells. Mirt2-knockdown enhanced ox-LDL-induced macrophage migration, lipid accumulation, inflammation, and inhibited cholesterol efflux. By contrast, Mirt2 overexpression displayed the opposite effects. Furthermore, Mirt2-knockdown inhibited NRF2 signaling and enhanced mitogen-activated protein kinase (MAPK) signaling, while Mirt2 overexpression displayed the opposite effects. Finally, the NRF2 inhibitor ML385 significantly reversed the above effects of Mirt2. In summary, Mirt2 served an important role in regulating lipid metabolism in macrophages via inhibiting MAPK signaling and activating the NRF2 signaling pathway.

Oltipraz ameliorates the progression of steatohepatitis in Nrf2-null mice fed a high-fat diet

Oltipraz, a synthetic dithiolethione, has chemopreventive effect through nuclear factor erythroid 2-related factor 2 (Nrf2) activation. Nrf2 is known to be involved in the development of experimental steatohepatitis in rodents. In this study, to evaluate the effect of oltipraz on lipid and bile acid metabolism, wild-type and Nrf2-null mice were fed the standard diet (containing 4% soybean oil) with or without oltipraz. Based on these results, we examined the effect of oltipraz on the experimental steatohepatitis in high-fat diet (containing 4% soybean oil and 20% lard) fed Nrf2-null mice. Oltipraz induced hepatic mRNA expression of peroxisome proliferator-activated receptor α, carnitine palmityl transferase 1, and bile salt export pump by Nrf2 independent mechanisms. In Nrf2-null mice fed a high-fat diet for 12 weeks, moderate to severe inflammation and fibrosis were observed. Oral administration of oltipraz suppressed the degree of inflammation and fibrosis in Nrf2-null mouse liver fed a high-fat diet. These histopathological findings approximately corresponded to the data of mRNA expression of tumor necrosis factor α, monocyte chemoattractant protein-1, Timp-1, and collagen type 1α1. These results indicated that oltipraz administration ameliorated liver injury by Nrf2 independent manner in a model of steatohepatitis generated by Nrf2-null mice with high-fat diet.

High-fat diet-induced increases in glucocorticoids contribute to the development of non-alcoholic fatty liver disease in mice

This study aimed to investigate the causal relationship between chronic ingestion of a high-fat diet (HFD)-induced secretion of glucocorticoids (GCs) and the development of non-alcoholic fatty liver disease (NAFLD). We have produced a strain of transgenic mice (termed L/L mice) that have normal levels of circulating corticosterone (CORT), the major type of GCs in rodents, but unlike wild-type (WT) mice, their circulating CORT was not affected by HFD. Compared to WT mice, 12-week HFD-induced fatty liver was less pronounced with higher plasma levels of triglycerides in L/L mice. These changes were reversed by CORT supplement to L/L mice. By analyzing a sort of lipid metabolism-related proteins, we found that expressions of the hepatic cluster of differentiation 36 (CD36) were upregulated by HFD-induced CORT and involved in CORT-mediated fatty liver. Dexamethasone, an agonist of the glucocorticoid receptor (GR), upregulated expressions of CD36 in HepG2 hepatocytes and facilitated lipid accumulation in the cells. In conclusion, the fat ingestion-induced release of CORT contributes to NAFLD. This study highlights the pathogenic role of CORT-mediated upregulation of hepatic CD 36 in diet-induced NAFLD.

Activation of activator protein-1-fibroblast growth factor 21 signaling attenuates Cisplatin hepatotoxicity

Fibroblast growth factor (Fgf/FGF) 21, which plays important roles in sugar, lipid and energy metabolism, has been accepted as a mito-stress marker gene. We recently reported that FGF21 expression can be up-regulated via activation of aryl hydrocarbon receptor (AhR) or glucocorticoid receptor (GR) and that FGF21 plays important cytoprotective roles. Cisplatin (cis-diamminedichloroplatinum, CDDP) is a widely used chemotherapeutic drug. Numerous adverse effects including hepatotoxicity have been noted during CDDP therapy. It is known that CDDP can induce mitochondrial dysfunction. The studies were designed to determine the regulation of Fgf/FGF21 expression by CDDP, and to characterize the underlying mechanisms of its regulation, as well as to determine the impact of gain or loss of Fgf/FGF21 function on the progression of CDDP hepatotoxicity. Our results showed that CDDP and phorbol ester induced mRNA and protein expression of Fgf/FGF21 and β-Klotho, two essential components of Fgf21 signaling, in mouse livers and cultured mouse/human hepatocytes. Luciferase reporter assays and ChIP-qPCR assays demonstrated that the cJun-AP-1 activation is responsible for CDDP- and phorbol ester-induced Fgf/FGF21 expression. Such induction is abolished after cotreated with AP-1 inhibitor SR11302. In addition, CDDP produces more severe liver injury in Fgf21-null than wild-type mice. Pre-treatment of GR activator dexamethasone or AhR activator β-Naphthoflavone, both of which can induce Fgf21 expression, attenuated CDDP-induced hepatotoxicity in vivo and in vitro. In conclusion, Fgf/FGF21-β-Klotho signaling can be activated via AP-1 activation. Gain of Fgf/FGF21 function attenuates the progression of CDDP hepatotoxicity, which may be considered clinically to improve CDDP therapy.

A Role of Stress Sensor Nrf2 in Stimulating Thermogenesis and Energy Expenditure

During chronic cold stress, thermogenic adipocytes generate heat through uncoupling of mitochondrial respiration from ATP synthesis. Recent discovery of various dietary phytochemicals, endogenous metabolites, synthetic compounds, and their molecular targets for stimulating thermogenesis has provided promising strategies to treat or prevent obesity and its associated metabolic diseases. Nuclear factor E2 p45-related factor 2 (Nrf2) is a stress response protein that plays an important role in obesity and metabolisms. However, both Nrf2 activation and Nrf2 inhibition can suppress obesity and metabolic diseases. Here, we summarized and discussed conflicting findings of Nrf2 activities accounting for part of the variance in thermogenesis and energy metabolism. We also discussed the utility of Nrf2-activating mechanisms for their potential applications in stimulating energy expenditure to prevent obesity and improve metabolic deficits.

Maternal, umbilical arterial metabolic levels and placental Nrf2/CBR1 expression in pregnancies with and without 25-hydroxyvitamin D deficiency

BACKGROUND

The aim of this case-control study was to document maternal, umbilical arterial metabolic levels and correlations in pregnancies with and without 25-hydroxyvitamin D [25(OH)D] deficiency, while, also investigating the expression of nuclear factor erythroid 2 related factor 2 (Nrf2) and carbonyl reductase 1 (CBR1) in the placenta.

METHODS

One hundred participants, 50 deficient for 25(OH)D and 50 normal, were recruited from among hospitalized single-term pregnant women who had elected for cesarean section. Umbilical arterial and placental samples were collected during cesarean section. Metabolic levels were assessed for the 25(OH)D deficiency and control groups' maternal, umbilical arterial samples. Nrf2 and CBR1 expression levels were investigated in the placentas of 12 pregnant women with 25(OH)D deficiency and 12 controls.

RESULTS

Compared with the control participants, the 25(OH)D deficient women had significantly higher triglyceride (TG) levels (3.80 ± 2.11 vs. 2.93 ± 1.16 mmol/L, 3.64 ± 1.84 vs. 2.81 ± 1.16 mmol/L, p < .01, .001); lower high density lipoprotein cholesterol (HDL-C) levels (1.54 ± 0.32 vs. 1.82 ± 0.63 mmol/L, 1.41 ± 0.72 vs. 2.44 ± 1.68 mmol/L, p < .001, .01) in both material blood and the umbilical artery. In addition, Nrf2 and CBR1 expression levels were lower in the maternal 25(OH)D deficient placenta.

CONCLUSION

25(OH)D deficient pregnant women have higher TG levels and lower HDL-C levels in both material blood and the umbilical artery. TG level is negatively correlated with 25(OH)D in both the maternal serum and infant umbilical artery. 25(OH)D deficiency also lowers placental expression of Nrf2 and CBR1.

Supplemental data for this article is available online at here.

Lipid overload impairs hepatic VLDL secretion via oxidative stress-mediated PKCδ-HNF4α-MTP pathway in large yellow croaker (Larimichthys crocea)

Lipid overload-induced hepatic steatosis is a major public health problem worldwide. However, the potential molecular mechanism is not completely understood. Herein, we found that high-fat diet (HFD) or oleic acid (OA) treatment induced oxidative stress which prevented the entry of hepatocyte nuclear factor 4 alpha (HNF4α) into the nucleus by activating protein kinase C delta (PKCδ) in vivo and in vitro in large yellow croaker (Larimichthys crocea). This reduced the level of microsomal triglyceride transfer protein (MTP) transcription, resulting in the impaired secretion of very-low-density lipoprotein (VLDL) and the abnormal accumulation of triglyceride (TG) in hepatocytes. Meanwhile, the detrimental effects induced by lipid overload could be partly alleviated by pretreating hepatocytes with Go6983 (PKCδ inhibitor) or N-acetylcysteine (NAC, reactive oxygen species (ROS) scavenger). In conclusion, for the first time, we revealed that lipid overload impaired hepatic VLDL secretion via oxidative stress-mediated PKCδ-HNF4α-MTP pathway in fish. This study may provide critical insights into potential intervention strategies against lipid overload-induced hepatic steatosis of fish and human beings.

The Interplay Between Mitochondrial Reactive Oxygen Species, Endoplasmic Reticulum Stress, and Nrf2 Signaling in Cardiometabolic Health

Significance: Mitochondria-derived reactive oxygen species (mtROS) are by-products of normal physiology that may disrupt cellular redox homeostasis on a regular basis. Nonetheless, failure to resolve sustained mitochondrial stress to mitigate high levels of mtROS might contribute to the etiology of numerous pathological conditions, such as obesity, insulin resistance, and cardiovascular disease (CVD). Recent Advances: Notably, recent studies have demonstrated that moderate mitochondrial stress might result in the induction of different stress response pathways that ultimately improve the organism's ability to deal with subsequent stress, a process termed mitohormesis. mtROS have been shown to play a key role in regulating this adaptation. Critical Issue: mtROS regulate the convergence of different signaling pathways that, when disturbed, might impair cardiometabolic health. Conversely, mtROS seem to be required to mediate activation of prosurvival pathways, contributing to improved cardiometabolic fitness. In the present review, we will primarily focus on the role of mtROS in the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway and examine the role of endoplasmic reticulum (ER) stress in coordinating the convergence of ER stress and oxidative stress signaling through activation of Nrf2 and activating transcription factor 4 (ATF4). Future Directions: The mechanisms underlying cardiometabolic protection in response to mitochondrial stress have only started to be investigated. Integrated understanding of how mtROS and ER stress cooperatively promote activation of prosurvival pathways might shed mechanistic insight into the role of mitohormesis in mediating cardiometabolic protection and might inform future therapeutic avenues for the treatment of metabolic diseases contributing to CVD. Antioxid. Redox Signal. 35, 252-269.