Molecular mechanisms and new treatment strategies for non-alcoholic steatohepatitis (NASH)

Effects of Deoxynivalenol and Its Acetylated Derivatives on Lipid Metabolism in Human Normal Hepatocytes

Deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON) belong to type B trichothecenes that are widely detected in agricultural products as one of the most common classes of mycotoxins. In the present study, we aimed to characterize the alteration of lipid metabolism in normal human hepatocytes by poisoning with DON and its acetylated derivatives. After verifying the hepatotoxicity of the three toxins, DON, 15-ADON, and 3-ADON, the mRNA expression was determined by transcriptomics, and the results showed that DON and 15-ADON had a significant regulatory effect on the transcriptome, in which glycerophospholipid metabolism pathway and phospholipase D signaling pathways have not been reported in studies of DON and its acetylated derivatives. For further validation, we explored lipid metabolism in depth and found that PC (15:0/16:0), PC (16:1/18:3), PC (18:1/22:6), PC (16:0/16:0), PC (16:0/16:1), PC (16:1/18:1), PC (14:0/18:2), PE (14:0/16:0) and PE (18:1/18:3) were downregulated for all nine lipids. Combined with the transcriptome results, we found that hepatic steatosis induced by the three toxins, DON, 15-ADON and 3-ADON, was associated with altered expression of genes related to lipid oxidation, lipogenesis and lipolysis, and their effects on lipid metabolism in L-02 cells were mainly realized through the PC-PE cycle.

Bile acid and nonalcoholic steatohepatitis: Molecular insights and therapeutic targets

BACKGROUND

Nonalcoholic steatohepatitis (NASH) has been the second most common cause of liver transplantation in the United States. To date, NASH pathogenesis has not been fully elucidated but is multifactorial, involving insulin resistance, obesity, metabolic disorders, diet, dysbiosis, and gene polymorphism. An effective and approved therapy for NASH has also not been established. Bile acid is long known to have physiological detergent function in emulsifying and absorbing lipids and lipid-soluble molecules within the intestinal lumen. With more and more in-depth understandings of bile acid, it has been deemed to be a pivotal signaling molecule, which is capable of regulating lipid and glucose metabolism, liver inflammation, and fibrosis. In recent years, a plethora of studies have delineated that disrupted bile acid homeostasis is intimately correlated with NASH disease severity.

AIMS

The review aims to clarify the role of bile acid in hepatic lipid and glucose metabolism, liver inflammation, as well as liver fibrosis, and discusses the safety and efficacy of some pharmacological agents targeting bile acid and its associated pathways for NASH.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Bile acid has a salutary effect on hepatic metabolic disorders, which can ameliorate liver fat accumulation and insulin resistance mainly through activating Takeda G-protein coupled receptor 5 and farnesoid X receptor. Moreover, bile acid also exerts anti-inflammation and anti-fibrosis properties. Furthermore, bile acid has great potential in nonalcoholic liver disease stratification and treatment of NASH.

Weight regain, but not weight loss exacerbates hepatic fibrosis during multiple weight cycling events in male mice

PURPOSE

Weight cycling is a phenomenon characterized by fluctuating body weight that is commonly observed in individuals employing intentional weight loss methods. Despite its prevalence, the impact of weight cycling on health remains equivocal. The current investigation aimed to examine the effects of weight cycling on liver health.

METHODS

The weight cycling model was established by switching the feeding method of mice between ad libitum (AL) and restricted intake (DR or 60% of AL) of the breeding diet to cause weight gain and weight loss, respectively. The weight cycling model comprised two and a half cycles, with one group terminating the experience during the weight-gain period (S-AL) and the other during the weight-loss period (S-DR). Liver tissue was collected to investigate morphology alterations, apoptosis, lipid metabolism, and mitochondrial homeostasis.

RESULTS

The results demonstrated that the termination point of weight cycling affected body weight and hepatic steatosis. All parameters examined in the S-DR mice exhibited a comparable trend to those observed in the DR mice. Notably, S-AL mice showed a significant increase in lipid metabolism-related proteins in the liver compared to AL-fed mice, along with reduced lipid droplets. Moreover, hepatic apoptosis and fibrosis were exacerbated in the S-AL mice compared to AL mice, whereas mitochondrial fusion, biogenesis, and mitophagy were decreased in the S-AL mice.

CONCLUSION

Weight cycling ending in weight gain exacerbated hepatic fibrosis, potentially by inducing apoptosis or disrupting mitochondrial homeostasis. Conversely, weight cycling ending in weight loss demonstrated beneficial effects on hepatic health.

Vinpocetine represses the progression of nonalcoholic steatohepatitis in mice by mediating inflammasome components via NF-κB signaling

BACKGROUND

Inflammasome activation is known to be involved in nonalcoholic steatohepatitis (NASH). Vinpocetine is a derivative of vincamine and is reported to suppress the activation of inflammasome.

METHODS

This study explored the therapeutical potential of Vinpocetine on NASH. Mice were fed with a choline-deficient (MCD) or chow diet in the presence or absence of Vinpocetine for 8 weeks. H&E staining and biochemical assays were determined to evaluate the hepatic steatosis and fibrosis symptoms. In addition, primary hepatocytes and Kupffer cells were isolated and induced by MCD or lipopolysaccharides/cholesterol crystals with or without Vinpocetine. ELISAs, qPCR, and Western blotting were applied to determine the levels of NASH-related biomarkers in both in vivo mouse model and in vitro cell models.

RESULTS

Treatment of Vinpocetine did not cause observable side effects against and MCD-induced cells and mouse NASH model. However, treatment of Vinpocetine ameliorated hepatic steatosis and fibrosis and suppressed the levels of alanine transaminase and aspartate transferase in the mouse NASH model. In addition, treatment of Vinpocetine suppressed the mRNA and protein levels of inflammasome components both in vitro and in vivo.

CONCLUSION

Vinpocetine suppressed NASH in mice by mediating inflammasome components via nuclear factor κB signaling.

Melatonin targets ferroptosis through bimodal alteration of redox environment and cellular pathways in NAFLD model

Ferroptosis is a non-conventional cellular death caused by lipid peroxide induced iron deposition. Intracellular lipid accumulation followed by generation of lipid peroxides is an hallmark of non-alcoholic fatty liver disease (NAFLD). Melatonin (MLT) is an important pineal hormone with tremendous antioxidant and anti-inflammatory properties. Various studies targeted ferroptosis in different diseases using melatonin. However, none of them focused the intrinsic mechanism of MLT's action to counteract ferroptosis in NAFLD. Hence, the present study investigated the role of MLT in improvement of NAFLD-induced ferroptosis. HepG2 cells were treated with free fatty acids (FFAs) to induce in vitro NAFLD state and C57BL/6 mice were fed with high-fat diet (HFD) followed by MLT administration. The results indicated that MLT administration caused the recovery from both FFA- and HFD-induced ferroptotic state via increasing GSH and SOD level, decreasing lipid reactive oxygen species (ROS) and malondialdehyde (MDA) level, increasing Nrf2 and HO-1 level to defend cells against an oxidative environment. MLT also altered the expression of two key proteins GPX4 and SLC7A11 back to their normal levels, which would otherwise cause ferroptosis. MLT also protected against histopathological damage of both liver tissue and HepG2 cells as depicted by Oil Red O, HE staining and immunofluorescence microscopy. MLT also had control over pAMPKα as well as PPARγ and PPARα responsible for lipid homeostasis and lipogenesis. In brief, MLT exerted its multifaceted effect in FFA- and HFD-induced NAFLD by retrieving cellular oxidative environment, reducing lipogenesis and lipid peroxidation and modulating Nrf2/HO-1 and GPX4/SLC7A11 axis to combat ferroptosis.

Hepatocytic Ballooning in Non-alcoholic Steatohepatitis: Bridging the Knowledge Gap and Charting Future Avenues

Non-alcoholic steatohepatitis (NASH) is emerging as a significant global health concern, characterized by hepatic lipid accumulation, inflammation, and hepatocellular injury. Hepatocytic ballooning, a histological feature of NASH, has gained prominence for its role in disease progression and potential as a therapeutic target. This review provides an overview of the current knowledge regarding hepatocytic ballooning in NASH, highlighting the key molecular and cellular mechanisms implicated in its development. We delve into the intricate interplay of metabolic dysregulation, oxidative stress, and lipid toxicity as drivers of hepatocytic ballooning, shedding light on the pathways responsible for its initiation and perpetuation. Furthermore, we explore the diagnostic challenges associated with hepatocytic ballooning and its significance as a prognostic indicator in NASH patients. While hepatocytic ballooning holds promise as a therapeutic target, this abstract discusses the various experimental and clinical approaches to ameliorate this histological hallmark. Potential interventions, including lifestyle modifications, pharmacological agents, and emerging therapies, are evaluated in terms of their efficacy and safety profiles. In conclusion, this review underscores the need to bridge the knowledge gap surrounding hepatocytic ballooning in NASH and emphasizes its importance in understanding disease pathogenesis and progression. By charting future research avenues and clinical strategies, we aspire to advance our comprehension of NASH and ultimately improve patient outcomes in this rapidly evolving field of hepatology.

Gut microbiome and metabolic-associated fatty liver disease: Current status and potential applications

Metabolic-associated fatty liver disease (MAFLD) is one of the most common chronic liver diseases worldwide. In recent years, the occurrence rate of MAFLD has been on the rise, mainly due to lifestyle changes, high-calorie diets, and imbalanced dietary structures, thereby posing a threat to human health and creating heavy social and economic burdens. With the development of 16S sequencing and integrated multi-omics analysis, the role of the gut microbiota (GM) and its metabolites in MAFLD has been further recognized. The GM plays a role in digestion, energy metabolism, vitamin synthesis, the prevention of pathogenic bacteria colonisation, and immunoregulation. The gut-liver axis is one of the vital links between the GM and the liver. Toxic substances in the intestine can enter the liver through the portal vascular system when the intestinal barrier is severely damaged. The liver also influences the GM in various ways, such as bile acid circulation. The gut-liver axis is essential in maintaining the body’s normal physiological state and plays a role in the onset and prognosis of many diseases, including MAFLD. This article reviews the status of the GM and MAFLD and summarizes the GM characteristics in MAFLD. The relationship between the GM and MAFLD is discussed in terms of bile acid circulation, energy metabolism, micronutrients, and signalling pathways. Current MAFLD treatments targeting the GM are also listed.

NOD1 activation in 3T3-L1 adipocytes confers lipid accumulation in HepG2 cells

AIMS

Activation of specific innate immune receptors has been characterized to modulate nutrient metabolism in individual metabolic tissue directly or indirectly via secretory molecules. Activation of the nucleotide-binding oligomerization domain-containing protein 1 (NOD1) in adipocytes has been reported to induce lipolysis linked with insulin resistance and inflammatory response. These cues are positioned to modulate metabolic action in distal organs through paracrine/endocrine signaling. Here, we assessed the role of NOD1-mediated lipolysis and inflammatory response in adipocytes to affect lipid metabolism in hepatocytes.

MAIN METHODS

Human hepatoma cells (HepG2) were exposed to conditioned medium obtained from 3 T3-L1 adipocytes pretreated with NOD1 ligand (iE-DAP) and the effects on lipid accumulation, inflammation and insulin response were assessed. Activation of mechanisms leading to hepatic lipid accumulation was investigated by gene expression analysis.

KEY FINDINGS

The conditioned medium from NOD1-activated 3 T3-L1 adipocytes (CM-DAP) induced lipid accumulation in HepG2 cells, driven by both lipolysis and inflammatory responses. The CM-DAP-induced lipid accumulation was independent to de novo lipogenesis and resulted from the enhanced transport of fatty acids inside and consequent increase in rate of triglycerides synthesis in hepatocytes. Moreover, CM-DAP-induced lipid accumulation instigated the expression of the markers of fatty acid oxidation and VLDL assembly for the export of triglycerides from hepatocyte. Furthermore, CM-DAP-induced lipid accumulation was associated with induction of inflammatory response and impairment of insulin signaling in HepG2 cells.

SIGNIFICANCE

Beyond showing liver-specific mechanisms to adipocytes-derived factors, our findings support the involvement of adipose tissue as a mediator in NOD1-mediated biological responses to modulate hepatic metabolism.

SIRT1/NFκB pathway mediates anti-inflammatory and anti-apoptotic effects of rosmarinic acid on in a mouse model of nonalcoholic steatohepatitis (NASH)

Nonalcoholic steatohepatitis (NASH) is considered as a common liver disease. SIRT1, a pivotal sensor, controls activation of metabolic, inflammatory and apoptotic pathways. Rosmarinic acid (RA) has positive effects on the liver injuries; nevertheless, its mechanisms are not completely studied. The aim of this study was to explore the role of rosmarinic acid on the pathways involved by SIRT1 for amelioration of a mouse model of NASH. To do this, C57/BL6 mice were divided into four equal groups (6 in each group). Animals received saline and rosmarinic acid as the control groups. NASH was induced by methionine-choline-deficient (MCD) diet. In the NASH + RA group, Rosmarinic acid was injected daily in mice fed on an MCD diet. Rosmarinic acid decreased plasma triglyceride, cholesterol, liver Steatosis and oxidative stress. Rosmarinic acid administration also increased SIRT1, Nrf2 and PPARα and decreased SREBP1c, FAS, NFκB and caspase3 expressions. Moreover, TNFα, IL6, P53, Bax/Bcl2 ratio and caspase3 expressions decreased. Our study demonstrated that remarkable effects of rosmarinic acid on the mice with NASH might be due to activation of SIRT1/Nrf2, SIRT1/NFκB and SIRT1/PPARα pathways, which alleviate hepatic steatosis, oxidative stress, inflammation and apoptosis.

Using adipose-derived mesenchymal stem cells to fight the metabolic complications of obesity: Where do we stand?

Obesity is a critical risk factor for the development of metabolic diseases, and its prevalence is increasing worldwide. Stem cell-based therapies have become a promising tool for therapeutic intervention. Among them are adipose-derived mesenchymal stem cells (ADMSCs), secreting numerous bioactive molecules, like growth factors, cytokines, and chemokines. Their unique features, including immunosuppressive and immunomodulatory properties, make them an ideal candidates for clinical applications. Numerous experimental studies have shown that ADMSCs can improve pancreatic islet cell viability and function, ameliorate hyperglycemia, improve insulin sensitivity, restore liver function, counteract dyslipidemia, lower pro-inflammatory cytokines, and reduce oxidative stress in the animal models. These results prompted scientists to use ADMSCs clinically. However, up to date, there have been few clinical studies or ongoing trails using ADMSCs to treat metabolic disorders such as type 2 diabetes mellitus (T2DM) or liver cirrhosis. Most human studies have implemented autologous ADMSCs with minimal risk of cellular rejection. Because the functionality of ADMSCs is significantly reduced in subjects with obesity and/or metabolic syndrome, their efficacy is questioned. ADMSCs transplantation may offer a potential therapeutic approach for the treatment of metabolic complications of obesity, but randomized controlled trials are required to establish their safety and efficacy in humans prior to routine clinical use.

Attenuating effects of allantoin on oxidative stress in a mouse model of nonalcoholic steatohepatitis: role of SIRT1/Nrf2 pathway

BACKGROUND AND PURPOSE

Nonalcoholic steatohepatitis (NASH) is considered a common and serious liver disease, which develops into cirrhosis, fibrosis, and even hepatocellular carcinoma. Oxidative stress is identified as an important factor in the induction and promotion of NASH. Allantoin is a natural and safe compound and has notable effects on lipid metabolism, inflammation, and oxidative stress. Therefore, this study was aimed to assess the role of allantoin on the oxidative stress and SIRT1/Nrf2 pathway in a mouse model of NASH.

EXPERIMENTAL APPROACH

C57/BL6 male mice received saline and allantoin (saline as the control and allantoin as the positive control groups). NASH was induced by a methionine-choline deficient diet (MCD). In the NASH-allantoin (NASH-Alla) group, allantoin was injected for 4 weeks in the mice feeding on an MCD diet. Afterward, histopathological, serum, oxidative stress, and western blot evaluations were performed.

FINDINGS/RESULTS

We found NASH provided hepatic lipid accumulation and inflammation. Superoxide dismutase (SOD) and glutathione (GSH) levels decreased, lipid peroxidation increased, and the expression of SIRT1 and Nrf2 downregulated. However, allantoin-treatment decreased serum cholesterol, ALT, and AST. Liver steatosis and inflammation were improved. Protein expression of SIRT1 and Nrf2 were upregulated and SOD, CAT, and GSH levels increased and lipid peroxidation decreased.

CONCLUSION AND IMPLICATIONS

It seems that the antioxidant effects of allantoin might have resulted from the activation of SIRT1/Nrf2 pathway and increase of cellular antioxidant power.

Berberine Alleviates Non-alcoholic Steatohepatitis Through Modulating Gut Microbiota Mediated Intestinal FXR Activation

Berberine is a natural plant alkaloid isolated from a diverse range of genera, it obtains anti-inflammatory, anti-obesity, and hepatoprotective properties, and is a promising agent for non-alcoholic steatohepatitis (NASH). Farnesoid X receptor (FXR) is a bile acid receptor and a drug target for NASH, however, the underlying mechanisms of berberine on regulating FXR are still unknown. In the present study, we feed mice with a 12-week high-fat diet with interval dextran sulfate sodium (0.5% in drinking water) diet to induce NASH, and treat the mice with berberine (100 mg/kg per day) via oral gavage for additional 4 weeks. We demonstrate that administration of berberine alleviates steatosis and infiltration of inflammatory cells in the liver of NASH mice. We apply 16S ribosomal DNA sequencing to screen the structure of gut microbiota, and ultra-performance liquid chromatography-tandem mass spectrometry analysis to determine the bile acid profiles. The results show that berberine modulates gut dysbiosis, and specifically increases the relative abundance of Clostridiales, Lactobacillaceae, and Bacteroidale. Berberine modulated microbiomes are associated with bile acid de-conjugation and transformation, which are consistent with the altered bile acid species (e.g., deoxycholic acid, ursodeoxycholic acid) upon berberine treatment. BA species that respond to berberine treatment are known FXR agonists, thus we performed quantitative Real Time-PCR and western blot to examine the FXR pathway, and find that berberine up-regulates intestinal FXR and fibroblast growth factor 15 (FGF15) expression, and the secretion of FGF15 further inhibits lipogenesis and nuclear factor-κB activation in the liver. Whereas the beneficial effects of berberine are blunted in FXR knockout mice. Our results reveal that berberine alleviates NASH by modulating the interplay of gut microbiota and bile acid metabolism, as well as the subsequent intestinal FXR activation.

Clinical Value and Role of miR-129-5p in Non-Alcoholic Fatty Liver Disease

This study was to evaluate the expression of miR-129-5p in non-alcoholic fatty liver (NAFLD) patients and its clinical value and explore its regulatory effect on insulin resistance (IR). A total of 117 NAFLD patients and 110 healthy controls were included. The levels of miR-129-5p were detected by qRT-PCR. To assess the diagnostic value of miR-129-5p for NAFLD, the receiver operating characteristic curve (ROC) was established. C57Bl/6 mice were supplied with high-fat diet to establish NAFLD model. Intraperitoneal insulin tolerance test (IPITT) was carried out to evaluate the effect of miR-129-5p on IR in NAFLD animal model. miR-129-5p was highly expressed in the serum of NAFLD patients, and patients with HOMA-IR ≥2.5 had higher level of miR-129-5p than those with HOMA-IR <2.5. miR-129-5p had the ability to differentiate NAFLD patients from healthy individuals and might be associated with the development of IR. Serum miR-129-5p was positively correlated with the levels of HOMA-IR, BMI, total cholesterol (TC), and triglyceride (TG) in NAFLD patients. Downregulation of miR-129-5p regulates lipid metabolism and insulin sensitivity in NAFLD mice model. MiR-129-5p was upregulated in NAFLD patients and might be a potential diagnostic biomarker. The regulatory effect of miR-129-5p on NAFLD may function by regulating lipid accumulation and insulin sensitivity.

FAM172A Deletion May Enhance Hepatic Steatosis by Promoting ER Stress

BACKGROUND

Endoplasmic reticulum (ER) stress is one of the major causes to the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Our previous study showed that maintains the homeostasis of ER could effectively alleviate NAFLD. In this study, we found that the loss of FAM172A increased ER stress.

AIMS

The aims of this study were to explore whether FAM172A could improve NAFLD by inhibiting ER stress.

METHODS

The expression levels of FAM172A and ER stress were detected by western blot. The method of immunofluorescence was used to determine FAM172A location. The interacted proteins of FAM172A were identified by immunocoprecipitation. The methods of MTS and caspase-3/7 activity were taken to confirm the effect of FAM172A on cell viability and proliferation. The expression levels of inflammation were detected by qPCR.

RESULTS

We confirmed that FAM172A might alleviate NAFLD through inhibiting ER stress. Loss of FAM172A increased the expressions of ATF6, peIF2α, but decreased the expression of IRE1α. Then, it was shown that FAM172A located in ER and FAM172A directly interacted with ATF6 and peIF2α and IRE1α. More importantly, the binding of FAM172A and eIF2a in tunicamycin-treated group increased significantly compared with the control group. However, the binding of FAM172A and ATF6 or IRE1α did not change. Next, we found that the lack of FAM172A could produce more apoptosis and inflammation.

CONCLUSIONS

Our results suggest that FAM172A improve steatosis by alleviating ER stress.

Restorative effect of adipose tissue-derived stem cells on impaired hepatocytes through Notch signaling in non-alcoholic steatohepatitis mice

Adipose tissue-derived stem cells (ADSCs) have been suggested as a novel treatment for non-alcoholic steatohepatitis (NASH); however, the mechanisms underlying their therapeutic effect remain poorly understood. In this study, we aimed to investigate the association of Notch signaling, which is crucial for cellular proliferation and differentiation in ADSC-mediated treatment of NASH. Flow cytometry analysis of ADSCs showed that they expressed the Notch ligands JAG1, DLL1, and DLL4. The expression of genes associated with the Notch signaling pathway was attenuated in hepatocytes of NASH model mice. We further observed ADSC-mediated activation of Notch signaling in these hepatocytes in addition to an increase in proliferating cell nuclear antigen⁺ cells and a decrease in TdT-mediated dUTP-biotin nick end labeling⁺ apoptotic cells. Co-culture of palmitic acid-induced steatotic hepatocytes and ADSCs resulted in the activation of Notch signaling and reduction of apoptosis of steatotic hepatocytes. Moreover, inhibition of Notch signaling by a γ-secretase inhibitor and knockdown of Notch ligands using siRNA attenuated the anti-apoptotic effect of co-cultured ADSCs in vitro. Our findings show that the Notch signaling pathway is involved in the inhibition of apoptosis and restoration of cellular proliferation of hepatocytes from NASH mice following ADSC treatment.

On the Relationship Between Non-alcoholic Fatty Liver Disease with Body Composition and Bone Mineral Density in Overweight/Obese Adolescents

Background: Nonalcoholic fatty liver disease (NAFLD) is a health problem growing in line with the rising prevalence of obesity in children and adolescents, which may be correlated with different metabolic abnormalities such as osteoporosis. Objectives: This study aimed to evaluate the possible relationship between NAFLD with body composition and bone mineral density (BMD) in obese and overweight adolescents. Methods: This cross-sectional study encompassed 70 adolescents aged 11 - 18 years and was conducted during March 2016 and September 2016 in Mashhad, Iran. Anthropometric parameters and blood biomarkers were measured. Fat mass, fat-free mass, and BMD were determined using dual-energy X‐ray absorptiometry (DXA) scans, and NAFLD was also assessed using Fibroscan. All statistical data were analyzed using SPSS software version 21. Multivariate linear regression assessed the relationship between liver fat content with bone-related indicators, and multivariate logistic regression detected the relationship between body composition and NAFLD. Results: Total and trunk fat mass were significantly correlated with higher NAFLD even after controlling for intervening factors (total fat mass, OR = 1.27; 95% CI, 1.016 to 1.59, P = 0.036; trunk fat mass, OR = 1.35; 95% CI, 0.97 to 1.88, P = 0.045). Moreover, liver fat content was significantly correlated with lower BMD Z-score after adjusting for gender, BMI Z-score, ALT, fat mass index, total lean mass, and physical activity (β = -0.285, P = 0.048). Conclusions: The findings of the present study suggest that excess adipose tissue is correlated with higher NAFLD. Moreover, liver steatosis may be correlated with decreased BMD Z-score in overweight/obese adolescents.

TWIST2 and the PPAR signaling pathway are important in the progression of nonalcoholic steatohepatitis

BACKGROUND

To investigate the roles of the transcription factors twist family bHLH transcription factor 1 (TWIST1), twist family bHLH transcription factor 2 (TWIST2), and peroxisome proliferator activated receptor gamma (PPARγ) in the progression of nonalcoholic steatohepatitis.

METHODS

The protein levels of TWIST1, TWIST2 and PPARγ were determined in the serum of nonalcoholic fatty liver disease (NAFLD) patients and healthy controls by enzyme-linked immunosorbent assay (ELISA). An in vivo model for fatty liver was established by feeding C57BL/6 J mice a high-fat diet (HFD). An in vitro model of steatosis was established by treating LO-2 cells with oleic acid (OA). RNA sequencing was performed on untreated and OA-treated LO-2 cells followed by TWIST1, TWIST2 and PPARγ gene mRNA levels analysis, Gene Ontology (GO) enrichment and pathway analysis.

RESULTS

The TWIST2 serum protein levels decreased significantly in all fatty liver groups (P < 0.05), while TWIST1 varied. TWIST2 tended to be lower in mice fed an HFD and was significantly lower at 3 months. Similarly, in the in vitro model, the TWIST2 protein level was downregulated significantly at 48 and 72 h after OA treatment. RNA sequencing of LO-2 cells showed an approximately 2.3-fold decrease in TWIST2, with no obvious change in TWIST1 and PPARγ. The PPAR signaling pathway was enriched, with 4 genes upregulated in OA-treated cells (P = 0.0018). The interleukin (IL)-17 and tumor necrosis factor (TNF) signaling pathways were enriched in OA-treated cells.

CONCLUSIONS

The results provide evidence that the TWIST2 and PPAR signaling pathways are important in NAFLD and shed light on a potential mechanism of steatosis.

New insight and potential therapy for NAFLD: CYP2E1 and flavonoids

Over the years, the prevalence of nonalcoholic fatty liver disease (NAFLD) has increased year by year; however, due to its complicated pathogenesis, there is no effective treatment so far. It is reported that Cytochrome P450 2E1 (CYP2E1) plays an indispensable role in the development of NAFLD, and numerous studies have shown that flavonoids have a hepatoprotective effect and can exert a beneficial effect on NAFLD by regulating the activity of CYP2E1. Therefore, flavonoids may become effective drugs for the treatment of NAFLD in the future. This prompted us to review the research progress of the pathological mechanism of NAFLD and the impact of CYP2E1 activity changes during the pathological process, and to summarize the protective effect of flavonoids against CYP2E1 activity.

Oscillating lncRNA Platr4 regulates NLRP3 inflammasome to ameliorate nonalcoholic steatohepatitis in mice

Background: Understanding the molecular events and mechanisms underlying development and progression of nonalcoholic steatohepatitis is essential in an attempt to formulating a specific treatment. Here, we uncover Platr4 as an oscillating and NF-κB driven lncRNA that is critical to the pathological conditions in experimental steatohepatitis Methods: RNA-sequencing of liver samples was used to identify differentially expressed lncRNAs. RNA levels were analyzed by qPCR and FISH assays. Proteins were detected by immunoblotting and ELISA. Luciferase reporter, ChIP-sequencing and ChIP assays were used to investigate transcriptional gene regulation. Protein interactions were evaluated by Co-IP experiments. The protein-RNA interactions were studied using FISH, RNA pull-down and RNA immunoprecipitation analyses Results: Cyclic expression of Platr4 is generated by the core clock component Rev-erbα via two RevRE elements (i.e., -1354/-1345 and -462/-453 bp). NF-κB transcriptionally drives Platr4 through direct binding to two κB sites (i.e., -1066/-1056 and -526/-516 bp), potentially accounting for up-regulation of Platr4 in experimental steatohepatitis. Intriguingly, Platr4 serves as a circadian repressor of Nlrp3 inflammasome pathway by inhibiting NF-κB-dependent transcription of the inflammasome components Nlrp3 and Asc. Loss of Platr4 down-regulates Nlrp3 inflammasome activity in the liver, blunts its diurnal rhythm, and sensitizes mice to experimental steatohepatitis, whereas overexpression of Platr4 ameliorates the pathological conditions in an Nlrp3-dependent manner. Mechanistically, Platr4 prevents binding of the NF-κB/Rxrα complex to the κB sites via a physical interaction, thereby inhibiting the transactivation of Nlrp3 and Asc by NF-κB. Conclusions:Platr4 functions to inactivate Nlrp3 inflammasome via intercepting NF-κB signaling. This lncRNA might be an attractive target that can be modulated to ameliorate the pathological conditions of steatohepatitis.

The role of the gut microbiome and diet in the pathogenesis of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease, with a prevalence that is increasing in parallel with the global rise in obesity and type 2 diabetes mellitus. The pathogenesis of NAFLD is complex and multifactorial, involving environmental, genetic and metabolic factors. The role of the diet and the gut microbiome is gaining interest as a significant factor in NAFLD pathogenesis. Dietary factors induce alterations in the composition of the gut microbiome (dysbiosis), commonly reflected by a reduction of the beneficial species and an increase in pathogenic microbiota. Due to the close relationship between the gut and liver, altering the gut microbiome can affect liver functions; promoting hepatic steatosis and inflammation. This review summarises the current evidence supporting an association between NAFLD and the gut microbiome and dietary factors. The review also explores potential underlying mechanisms underpinning these associations and whether manipulation of the gut microbiome is a potential therapeutic strategy to prevent or treat NAFLD.

Sijunzi, Lizhong, and Fuzilizhong Decoction Alleviate Nonalcoholic Fatty Liver Disease through Activation of PPAR Pathway

OBJECTIVE

Sijunzi, Lizhong, and Fuzilizhong decoction were traditional Chinese classic formulations, which are widely used in clinical treatment, and the underlying mechanism is unclear. In this study, we aim to investigate the molecular mechanisms underlying the protective effects of Sijunzi, Lizhong, and Fuzilizhong on nonalcoholic fatty liver disease (NAFLD).

METHODS

Male Wistar rats were fed a high-fat diet for four weeks to induce NAFLD and were thereafter administered Sijunzi (8 g/kg/d), Lizhong (10 g/kg/d), or Fuzilizhong (10 g/kg/d) by gavage for four weeks. Hepatic damage, lipid accumulation, inflammation, autophagy, and peroxisome proliferator-activated receptor-α signaling were evaluated.

RESULTS

The high-fat diet-fed rats showed typical symptoms of NAFLD, including elevated levels of hepatic damage indicators, increased hepatic lipid deposition and fibrosis, severe liver inflammation, and prominent autophagy. Upon administration of Sijunzi, Lizhong, and Fuzilizhong, liver health was improved remarkably, along with ameliorated symptoms of NAFLD. In addition, NAFLD-suppressed peroxisome proliferator-activated receptor-α signaling was reactivated after treatment with the three types of decoctions.

CONCLUSIONS

The results collectively signify the effective therapeutic and protective functions of Sijunzi, Lizhong, and Fuzilizhong against NAFLD and demonstrate the potential of Chinese herbal medication in mitigating the symptoms of liver diseases. Novelty of the Work. Traditional Chinese herbal medicine has been used for centuries to treat various diseases, but the molecular mechanisms of individual ingredients have rarely been studied. The novelty of our work lies in elucidating the specific signaling pathways involved in the control of NAFLD using three common Chinese herbal decoctions. We suggest that natural herbal formulations can be effective therapeutic agents to combat against NAFLD.

Nonalcoholic Fatty Liver Disease (NAFLD) and Hepatic Cytochrome P450 (CYP) Enzymes

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive fat in the liver. An international consensus panel has recently proposed to rename the disease to metabolic dysfunction associated with fatty liver disease (MAFLD). The disease can range from simple steatosis (fat accumulation) to nonalcoholic steatohepatitis (NASH) which represents a severe form of NAFLD and is accompanied by inflammation, fibrosis, and hepatocyte damage in addition to significant steatosis. This review collates current knowledge of changes in human hepatic cytochrome P450 enzymes in NAFLD. While the expression of these enzymes is well studied in healthy volunteers, our understanding of the alterations of these proteins in NAFLD is limited. Much of the existing knowledge on the subject is derived from preclinical studies, and clinical translation of these findings is poor. Wherever available, the effect of NAFLD on these proteins in humans is debatable and currently lacks a consensus among different reports. Protein expression is an important in vitro physiological parameter controlling the pharmacokinetics of drugs and the last decade has seen a rise in the accurate estimation of these proteins for use with physiologically based pharmacokinetic (PBPK) modeling to predict drug pharmacokinetics in special populations. The application of label-free, mass spectrometry-based quantitative proteomics as a promising tool to study NAFLD-associated changes has also been discussed.

The food contaminant deoxynivalenol provokes metabolic impairments resulting in non-alcoholic fatty liver (NAFL) in mice

The ribotoxin deoxynivalenol (DON) is a trichothecene found on cereals responsible for mycotoxicosis in both humans and farm animals. DON toxicity is characterized by reduced food intake, diminished nutritional efficiency and immunologic effects. The present study was designed to further characterize the alterations in energy metabolism induced by DON intoxication. We demonstrated that acute DON intoxication triggered liver steatosis associated with an altered expression of genes related to lipids oxidation, lipogenesis and lipolysis. This steatosis was concomitant to anorexia, hypoglycemia and a paradoxical transient insulin release. DON treatment resulted also in stimulation of central autonomic network regulating sympathetic outflow and adrenaline and glucocorticoids secretion. Furthermore, an increased expression of genes linked to inflammation and reticulum endoplasmic stress was observed in the liver of DON-treated mice. Finally, we propose that lipids mobilization from adipose tissues (AT) induced by DON intoxication drives hepatic steatosis since (1) genes encoding lipolytic enzymes were up-regulated in AT and (2) plasma concentration of triglycerides (TGs) and non-esterified fatty acids were increased during DON intoxication. Altogether, these data demonstrate that DON induced hormonal and metabolic dysregulations associated with a spectrum of hepatic abnormalities, evocative of a non-alcoholic fatty liver disease.

Oxidative Stress Management in Chronic Liver Diseases and Hepatocellular Carcinoma

Chronic viral hepatitis B and C and non-alcoholic fatty liver disease (NAFLD) have been widely acknowledged to be the leading causes of liver cirrhosis and hepatocellular carcinoma. As anti-viral treatment progresses, the impact of NAFLD is increasing. NAFLD can coexist with chronic viral hepatitis and exacerbate its progression. Oxidative stress has been recognized as a chronic liver disease progression-related and cancer-initiating stress response. However, there are still many unresolved issues concerning oxidative stress, such as the correlation between the natural history of the disease and promising treatment protocols. Recent findings indicate that oxidative stress is also an anti-cancer response that is necessary to kill cancer cells. Oxidative stress might therefore be a cancer-initiating response that should be down regulated in the pre-cancerous stage in patients with risk factors for cancer, while it is an anti-cancer cell response that should not be down regulated in the post-cancerous stage, especially in patients using anti-cancer agents. Antioxidant nutrients should be administered carefully according to the patients’ disease status. In this review, we will highlight these paradoxical effects of oxidative stress in chronic liver diseases, pre- and post-carcinogenesis.

The effect of PNPLA3 polymorphism as gain in function mutation in the pathogenesis of non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is often associated with metabolic syndrome (type 2 diabetes, hypertension, hypertriglyceridemia, insulin resistance, and obesity). NAFLD is multi-factorial in pathogenesis with some genetic predisposition. The variant patatin-like phospholipase domain-containing protein 3 (PNPLA3) is known to be an independent risk factor for hepatocellular cancer (HCC). The aim of this study was to investigate the role of PNPLA3 polymorphism as the risk factor for NAFLD.

METHODOLOGY

Patients had histological, ultrasonographic, biopsy evidence of NAFLD (n=248) and 81 controls were studied for PNPLA3 polymorphism. PNPLA3 genotyping was done from peripheral blood DNA by real-time polymerase chain reaction (RT-PCR).

RESULTS

PNPLA3 genotyping of the groups NAFLD (CC [n = 76], CG [n = 83], GG [n = 89]) and control (CC [n= 42], CG [n = 22], GG [n = 17]) was determined. In the patient group, the G allele was 261 (52.63%) and the C allele was 235 (47.37%), whereas in the control group, the G allele was 56 (34.54%) and the C allele was 106 (65.43%). In our study, 53 out of 174 women had GG allele and 54 out of 155 men had GG allele.

CONCLUSION

The findings suggest that there is a predominant relationship between men with PNPLA3 I148M variant with NAFLD in women. Patients with NAFLD carrying PNPLA3 rs738409 G>C variant are at higher risk of NAFLD.

The Effect of Autophagy on Chronic Intermittent Hypobaric Hypoxia Ameliorating Liver Damage in Metabolic Syndrome Rats

Aim

Our previous study demonstrated that chronic intermittent hypobaric hypoxia (CIHH) can confer hepatic protection by reducing endoplasmic reticulum stress (ERS) in high-fat-high-fructose induced metabolic syndrome (MS) rats. It is known that there is a functional coupling between autophagy and ERS. This study aimed to investigate the effect of CIHH on autophagy function and adenosine mono-phosphate-activated protein kinase-mammalian target of rapamycin (AMPKα-mTOR) signaling pathway in hepatic tissue of MS rats.

Main Methods

6-week old male Sprague-Dawley rats were randomly divided into: control (CON), CIHH (treated with hypobaric hypoxia simulating 5000-m altitude for 28 days, 6 h daily), MS (induced by 16-week high fat diet and 10% fructose water feeding), and MS + CIHH groups (exposed to CIHH after 16-week MS model). Food and water intakes, body weight, Lee's index, fat coefficient, systolic arterial pressure, blood biochemicals, and histopathology of liver were measured, the expression of phosphorylated (p)-AMPK, p-mTOR, autophagy-related and ERS-related proteins were assayed in hepatic tissue.

Key Findings

The MS rats displayed obesity, hypertension, polydipsia, glucose and lipids metabolism disorders, increased inflammatory cytokine, hepatic tissue morphological and functional damage, and the up-regulated expressions of ERS-related, autophagy-related proteins and p-mTOR, and the down-regulated expression of p-AMPKα. All aforementioned abnormalities in MS rats were ameliorated in MS + CIHH rats.

Significance

In conclusion CIHH confers hepatic protection through activating AMPK-mTOR signaling pathway and the autophagy function, thus inhibiting ERS in hepatic tissue.

Obesity-Induced Upregulation of ZBTB7A Promotes Lipid Accumulation through SREBP1

Objective

Nonalcoholic fatty liver disease (NAFLD) is among the most common chronic liver diseases. However, the pathogenesis of NAFLD is not still unclear. This study aims at evaluating the role of zinc finger and BTB domain-containing 7A (ZBTB7A) in NAFLD.

Methods

Western blotting, real-time reverse transcription PCR (RT-PCR), and immunohistochemistry were submitted to evaluate the level of ZBTB7A in the high fatty diet- (HFD-) induced NAFLD mouse model. In vitro, the expression of ZBTB7A was assessed in oleic acid- (OA-) induced HepG2 cells with western blotting and RT-PCR. The luciferase reporter assay was used to estimate the effect of ZBTB7A on the SREBP1 and NF-κB, and the ChIP assay was subjected to evaluate the direct binding to the SREBP1 promoter. Oil Red staining was used to detect lipid accumulation, and the ELISA was used to verify the levels of TG, T-CHO, and MDA. ZBTB7A was knocked down with siRNA, and RT-PCR was performed to analyze the lipogenesis-, fatty acid transporter-, and oxidation metabolism-related genes expression. The levels of ZBTB7A in primary hepatocyte, Kupffer, and hepatic stellate cells (HSCs) were tested by RT-PCR.

Results

The upregulation of ZBTB7A expression was assessed in NAFLD mice, and ZBTB7A expression was positively correlated with TNFα, IL-6, TG, T-CHO, and MDA. ZBTB7A was highly expressed in the hepatocytes. In vitro, OA-induced ZBTB7A expression and ZBTB7A expression were closely associated with SREBP1c. ZBTB7A could activate the promoter activity of SREBP1 and activate NF-κB activity. Interestingly, the direct binding of ZBTB7A in the SREBP1 promoter was acquired in HepG2 cells. Inhibition of ZBTB7A expression could attenuate OA-induced lipid accumulation, inhibit the expression of the lipogenesis-related genes and fatty acid transporter genes, and promote the expression of oxidation metabolism-related genes.

Conclusion

ZBTB7A plays a significant role in the development process of NAFLD, and obesity-induced upregulation of ZBTB7A promotes lipid accumulation through activation of SREBP1 and NF-κB. ZBTB7A may be a potential novel target for the therapy of NAFLD.

Cytochrome P450 endoplasmic reticulum-associated degradation (ERAD): therapeutic and pathophysiological implications

The hepatic endoplasmic reticulum (ER)-anchored cytochromes P450 (P450s) are mixed-function oxidases engaged in the biotransformation of physiologically relevant endobiotics as well as of myriad xenobiotics of therapeutic and environmental relevance. P450 ER-content and hence function is regulated by their coordinated hemoprotein syntheses and proteolytic turnover. Such P450 proteolytic turnover occurs through a process known as ER-associated degradation (ERAD) that involves ubiquitin-dependent proteasomal degradation (UPD) and/or autophagic-lysosomal degradation (ALD). Herein, on the basis of available literature reports and our own recent findings of in vitro as well as in vivo experimental studies, we discuss the therapeutic and pathophysiological implications of altered P450 ERAD and its plausible clinical relevance. We specifically (i) describe the P450 ERAD-machinery and how it may be repurposed for the generation of antigenic P450 peptides involved in P450 autoantibody pathogenesis in drug-induced acute hypersensitivity reactions and liver injury, or viral hepatitis; (ii) discuss the relevance of accelerated or disrupted P450-ERAD to the pharmacological and/or toxicological effects of clinically relevant P450 drug substrates; and (iii) detail the pathophysiological consequences of disrupted P450 ERAD, contributing to non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) under certain synergistic cellular conditions.

A simple method for inducing nonalcoholic steatohepatitis with fibrosis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is increasingly occurring in sedentary people, and may progress to NASH and hepatocellular carcinoma. It is essential to design affordable animal models for the study of various diseases, including fatty liver, which was the aim of the study. In this study, a high-fat diet was devised that triggers NASH's animal model quickly and easily. High-fat diet (HFD) was used both with intra-mouth oral gavage and in combination with animal pellets.

METHODS

Twenty-four male C57BL/6J mice were divided into HFD and ND groups, which received a high-fat diet and a normal diet, respectively. At the end of the experiment (fourth week of treatment), body and liver weights, biochemical parameters, PPAR-α gene expression and histopathologic characteristics of the liver were evaluated.

RESULTS

During 4 weeks, body weight of mice did not show a significant increase in the HFD group compared to the ND group, while weight gain of the liver was significant. Histological assessment of the HFD group's liver confirmed NASH symptoms. In the HFD group, HDL-c, SOD, catalase, FRAP, adiponectin, and PPAR-α decreased significantly, and lipid profiles, hepatic enzymes, MDA, leptin, and TNF-α showed a significant increase compared to the ND group.

CONCLUSION

Our high-fat diet has successfully induced all aspects of NASH with fibrosis in 4 weeks, and with low cost.

Western Diet-Induced Metabolic Alterations Affect Circulating Markers of Liver Function before the Development of Steatosis

Since nutrition might have a significant impact on liver function, we analyzed the early effect of Western-type diet on hepatic tissue and lipid and drug metabolism in Wistar–Kyoto rats (n = 8); eight rats fed with a standard diet were used as controls. Histological analysis of liver tissue was performed, and plasma biochemical parameters were measured. Plasma concentration of six bile acids was determined by ultra-liquid chromatography-tandem mass spectrometry UHPLC-MS/MS. Hepatic gene expressions of enzymes involved in drug and lipid metabolism were assessed by means of real-time reverse transcription (qRT)-PCR. Liver of rats fed with a Western diet did not show macroscopic histological alterations, but number and diameter of lipid droplets increased, as well as DGAT1, GPAT4, SCD, FASN and SREBP2 expression. Furthermore, Western diet-fed animals showed an increase in the activation of hepatic stellate cells and macrophage number in liver tissue, as well as a significant increase in AST and bilirubin levels (p < 0.01), and in the LDL:HDL cholesterol ratio (p < 0.001). Plasma chenodeoxycholic acid concentration increased significantly, whereas cholic acid decreased (p < 0.05), and cytochrome P450 genes were generally downregulated. Significant changes in hepatic lipid and drug metabolism are early induced by the Western diet, prior to steatosis development. Such changes are associated with a peculiar alteration in circulating bile acids, which could represent an early marker of non-alcoholic fatty liver disease (NAFLD) development.

Hepatic ferroptosis plays an important role as the trigger for initiating inflammation in nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a metabolic liver disease that progresses from simple steatosis to the disease state of inflammation and fibrosis. Previous studies suggest that apoptosis and necroptosis may contribute to the pathogenesis of NASH, based on several murine models. However, the mechanisms underlying the transition of simple steatosis to steatohepatitis remain unclear, because it is difficult to identify when and where such cell deaths begin to occur in the pathophysiological process of NASH. In the present study, our aim is to investigate which type of cell death plays a role as the trigger for initiating inflammation in fatty liver. By establishing a simple method of discriminating between apoptosis and necrosis in the liver, we found that necrosis occurred prior to apoptosis at the onset of steatohepatitis in the choline-deficient, ethionine-supplemented (CDE) diet model. To further investigate what type of necrosis is involved in the initial necrotic cell death, we examined the effect of necroptosis and ferroptosis inhibition by administering inhibitors to wild-type mice in the CDE diet model. In addition, necroptosis was evaluated using mixed lineage kinase domain-like protein (MLKL) knockout mice, which is lacking in a terminal executor of necroptosis. Consequently, necroptosis inhibition failed to block the onset of necrotic cell death, while ferroptosis inhibition protected hepatocytes from necrotic death almost completely, and suppressed the subsequent infiltration of immune cells and inflammatory reaction. Furthermore, the amount of oxidized phosphatidylethanolamine, which is involved in ferroptosis pathway, was increased in the liver sample of the CDE diet-fed mice. These findings suggest that hepatic ferroptosis plays an important role as the trigger for initiating inflammation in steatohepatitis and may be a therapeutic target for preventing the onset of steatohepatitis.

Paradoxical Roles of Oxidative Stress Response in the Digestive System before and after Carcinogenesis

Oxidative stress is recognized as a cancer-initiating stress response in the digestive system. It is produced through mitochondrial respiration and induces DNA damage, resulting in cancer cell transformation. However, recent findings indicate that oxidative stress is also a necessary anticancer response for destroying cancer cells. The oxidative stress response has also been reported to be an important step in increasing the anticancer response of newly developed molecular targeted agents. Oxidative stress might therefore be a cancer-initiating response that should be downregulated in the precancerous stage in patients at risk of cancer but an anticancer cell response that should not be downregulated in the postcancerous stage when cancer cells are still present. Many commercial antioxidant agents are marketed as “cancer-eliminating agents” or as products to improve one’s health, so cancer patients often take these antioxidant agents. However, care should be taken to avoid harming the anticancerous oxidative stress response. In this review, we will highlight the paradoxical effects of oxidative stress and antioxidant agents in the digestive system before and after carcinogenesis.

Adiponectin homolog novel osmotin protects obesity/diabetes-induced NAFLD by upregulating AdipoRs/PPARα signaling in ob/ob and db/db transgenic mouse models

BACKGROUND

In metabolic disorders, adiponectin and adiponectin receptors (AdipoR1/R2) signaling has a key role in improving nonalcoholic fatty liver disease (NAFLD) in obesity-associated diabetes.

OBJECTIVE

To the best of our knowledge, here, we reported for the first time the underlying mechanistic therapeutic efficacy of the novel osmotin, a homolog of mammalian adiponectin, against NAFLD in leptin-deficient ob/ob and db/db mice.

METHODS

The ob/ob and db/db mice were treated with osmotin at a dose of 5 μg/g three times a week for two weeks. To co-relate the in vivo results we used the human liver carcinoma HepG2 cells, subjected to knockdown with small siRNAs of AdipoR1/R2 and PPARα genes and treated with osmotin and palmitic acid (P.A.). MTT assay, Western blotting, immunohistofluorescence assays, and plasma biochemical analyses were applied.

RESULTS

Osmotin stimulated AdipoR1/R2 and its downstream APPL1/PPAR-α/AMPK/SIRT1 pathways in ob/ob and db/db mice, and HepG2 cells exposed to P.A. Mechanistically, we confirmed that knockdown of AdipoR1/R2 and PPARα by their respective siRNAs abolished the osmotin activity in HepG2 cells exposed to P.A. Overall, the in vivo and in vitro results suggested that osmotin protected against NAFLD through activation of AdipoR1/R2 and its downstream APPL1/PPAR-α/AMPK/SIRT1 pathways as shown by the reduced body weight, blood glucose level and glycated hemoglobin, improved glucose tolerance, attenuated insulin resistance and hepatic glucogenesis, regulated serum lipid parameters, and increased fatty acid oxidation and mitochondrial functions.

CONCLUSION

Our findings strongly suggest that novel osmotin might be a potential novel therapeutic tool against obesity/diabetes-induced NAFLD and other metabolic disorders.

Pegbelfermin (BMS-986036), PEGylated FGF21, in Patients with Obesity and Type 2 Diabetes: Results from a Randomized Phase 2 Study

OBJECTIVE

Obesity and type 2 diabetes mellitus (T2DM) are risk factors for nonalcoholic fatty liver disease, including nonalcoholic steatohepatitis. This study assessed pegbelfermin (BMS-986036), recombinant PEGylated human fibroblast growth factor 21 (FGF21), in patients with obesity and T2DM predisposed to fatty liver.

METHODS

In this randomized, double-blind, placebo-controlled study, patients with T2DM and BMI of 30 to 50 kg/m² received subcutaneous pegbelfermin (1, 5, or 20 mg daily or 20 mg weekly; n = 96) or placebo (n = 24) for 12 weeks. Primary end points were safety, tolerability, and change in HbA1c. Additional end points included insulin sensitivity, lipids, adiponectin, and disease progression biomarkers.

RESULTS

There were no significant effects of pegbelfermin versus placebo on HbA1c. Pegbelfermin 20 mg/d significantly improved high-density lipoprotein cholesterol (P = 0.015) and triglycerides (P = 0.037). All pegbelfermin regimens significantly increased adiponectin levels; 20-mg daily and weekly regimens decreased serum PRO-C3. Most adverse events were mild; the most frequent adverse events were injection-site bruising and diarrhea.

CONCLUSIONS

Twelve-week pegbelfermin treatment did not impact HbA1c concentrations, but QW and higher daily doses were associated with improved metabolic parameters and fibrosis biomarkers in patients with obesity and T2DM predisposed to fatty liver. These results support evaluation of pegbelfermin in patients with obesity-related metabolic diseases (e.g., nonalcoholic steatohepatitis).

Effects of high fat medium conditions on cellular gene expression profile: a network analysis approach

AIM

This study aimed to evaluate high fat medium (HFM) effect on the gene expression profile of human Sk-hep1 cells and to determine critical differential proteins.

BACKGROUND

There is a correlation between high fat diet (HFD), obesity, and non-alcoholic fatty liver disease. Despite wide range of investigations, understanding molecular mechanism of HFD effect on onset and progression of NAFLD warrants further examination. In this study, network analysis is applied to obtain a clear perspective about HFD effects and NAFLD.

METHODS

Gene expression profiles of human Sk-hep1 cells treated with HFM versus controls were extracted from GEO. Data were analyzed by GEO2R where the significant and characterized DEGs were included in the PPI network. The top 10 nodes of query DEGs based on four centrality parameters were selected to determine central nodes. The common hub nodes with at least other one central group were identified as central nodes. Action map was provided for the introduced central nodes.

RESULTS

Heterogeneous nuclear ribonucleoprotein family including A1, A2/B1, D, R, and D-like, and five proteins (PRPF40A, SRSF1, PCF11, LSM8, and HSP90AA1) were introduced as differential proteins.

CONCLUSION

mRNA processing and several biological terms including hypoxia and oxidative stress, apoptosis, regulation of cell morphology and cytoskeletal organization, and differentiation of micro tubes were introduced as dysregulated terms under HFM condition.

Effects of alkaline-electrolyzed and hydrogen-rich water, in a high-fat-diet nonalcoholic fatty liver disease mouse model

AIM

To identify the effect of hydrogen-rich water (HRW) and electrolyzed-alkaline water (EAW) on high-fat-induced non-alcoholic fatty acid disease in mice.

METHODS

Mice were divided into four groups: (1) Regular diet (RD)/regular water (RW); (2) high-fat diet (HFD)/RW; (3) RD/EAW; and (4) HFD/EAW. Weight and body composition were measured. After twelve weeks, animals were sacrificed, and livers were processed for histology and reverse-transcriptase polymerase chain reaction. A similar experiment was performed using HRW to determine the influence and importance of molecular hydrogen (H₂) in EAW. Finally, we compared the response of hepatocytes isolated from mice drinking HRW or RW to palmitate overload.

RESULTS

EAW had several properties important to the study: (1) pH = 11; (2) oxidation-reduction potential of -495 mV; and (3) H₂ = 0.2 mg/L. However, in contrast to other studies, there were no differences between the groups drinking EAW or RW in either the RD or HFD groups. We hypothesized that the null result was due to low H₂ concentrations. Therefore, we evaluated the effects of RW and low and high HRW concentrations (L-HRW = 0.3 mg H₂/L and H-HRW = 0.8 mg H₂/L, respectively) in mice fed an HFD. Compared to RW and L-HRW, H-HRW resulted in a lower increase in fat mass (46% vs 61%), an increase in lean body mass (42% vs 28%), and a decrease in hepatic lipid accumulation (P < 0.01). Lastly, exposure of hepatocytes isolated from mice drinking H-HRW to palmitate overload demonstrated a protective effect from H₂ by reducing hepatocyte lipid accumulation in comparison to mice drinking regular water.

CONCLUSION

H₂ is the therapeutic agent in electrolyzed-alkaline water and attenuates HFD-induced nonalcoholic fatty liver disease in mice.

Establishment and Comparison of Juvenile Female Mouse Models of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis

Experimental research has successfully established an adult offspring animal model of nonalcoholic fatty liver disease (NAFLD), but the female offspring model of NAFLD in young age has not been well characterized yet. The aim of this study was to present a direct comparison of the maternal versus postweaning female juvenile NAFLD and nonalcoholic steatohepatitis (NASH) animal models. Four different female mouse models were established and compared using different high-fat diet feeding (HF) strategies in maternal mice and their offspring. The models were non-HF maternal mice and HF offspring with high-high fat (C/HHF), non-HF maternal mice and HF offspring with low-high fat (C/LHF), HF maternal mice and offspring both with high-high fat (HHF/HHF), and HF maternal mice and offspring both with low-high fat (LHF/LHF). A female control group (C/C) was also established. The offspring mice were raised to the age of 8 weeks and then euthanized. Blood glucose levels, lipid profiles, liver function, and triglycerides/total cholesterol contents were examined. Hepatic morphology and superoxide anion levels were evaluated. The nicotinamide-adenine dinucleotide phosphate activity and related regulatory subunits protein expression in the liver tissue were also determined. Our data demonstrated that offspring fat intake contributed to the successful establishment of NAFLD and maternal-offspring fat intake contributed to the successful establishment of NASH in juvenile female mice. Offspring high-fat exposure might be associated with the development of NAFLD and maternal high-fat exposure might be associated with the development of NASH in juvenile female offspring. Higher calories from a fat diet program (both in maternal and offspring) are more prone to inducing liver injury in offspring. In addition, the combination of the aforementioned two factors could aggravate this process. Moreover, oxidative stress was prominent in the juvenile female mouse model of NAFLD/NASH, and the mechanism might be related to the activation of liver NADPH oxidase.

NASH Syndrome: The Coming Epidemic

Nonalcoholic steatohepatitis (NASH) is a serious and rapidly growing problem affecting a population that was not previously recognized as high risk. Although treatments are limited, shedding light on those with a predisposition may allow for primary prevention, as there is presently no cure other than liver transplant. This study examines the risk factors, genetic predisposition, pathophysiology, and treatment options.

Beneficial and Paradoxical Roles of Anti-Oxidative Nutritional Support for Non-Alcoholic Fatty Liver Disease

Oxidative stress is being recognized as a key factor in the progression of chronic liver disease (CLD), especially non-alcoholic fatty liver disease (NAFLD). Many NAFLD treatment guidelines recommend the use of antioxidants, especially vitamin E. Many prospective studies have described the beneficial effects of such agents for the clinical course of NAFLD. However, as these studies are usually short-term evaluations, lasting only a few years, whether or not antioxidants continue to exert favorable long-term effects, including in cases of concomitant hepatocellular carcinoma, remains unclear. Antioxidants are generally believed to be beneficial for human health and are often commercially available as health-food products. Patients with lifestyle-related diseases often use such products to try to be healthier without practicing lifestyle intervention. However, under some experimental NAFLD conditions, antioxidants have been shown to encourage the progression of hepatocellular carcinoma, as oxidative stress is toxic for cancer cells, just as for normal cells. In this review, we will highlight the paradoxical effects of antioxidants against NAFLD and related hepatocellular carcinoma.

Role of MicroRNAs in Pathophysiology of Non-alcoholic Fatty Liver Disease and Non-alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder worldwide. It includes wide range of diseases from different subtypes of simple steatosis to non-alcoholic steatohepatitis (NASH), which may be complicated by liver fibrosis, cirrhosis, or hepatocellular carcinoma. Of the epigenetic factors that play a key role in the progression of it, is microRNAs (miRNAs).

MiRNAs are short non-coding RNAs of 22-23 nucleotides in length, which regulate a large number of genes that have a critical role in regulation of lipid and cholesterol biosynthesis in hepatocytes. MiRNAs can be used as a very powerful biomarker to diagnosis and follow-up any disorder, such as NAFLD and NASH with a high specificity and sensitivity. The aim of this study was to review the role of different miRNAs in the pathophysiology of NASH and NAFLD

Effect of celastrol on toll‑like receptor 4‑mediated inflammatory response in free fatty acid‑induced HepG2 cells

Toll-like receptor 4 (TLR4)-mediated immune and inflammatory signaling serves a pivotal role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Our previous study demonstrated that celastrol treatment was able to improve hepatic steatosis and inhibit the TLR4 signaling cascade pathway in type 2 diabetic rats. The present study aimed to investigate the effects of celastrol on triglyceride accumulation and inflammation in steatotic HepG2 cells, and the possible mechanisms responsible for the regulation of cellular responses following TLR4 gene knockdown by small interfering RNA (siRNA) in vitro. A cell model of hepatic steatosis was prepared by exposing the HepG2 cells to free fatty acid (FFA) in the absence or presence of celastrol. Intracellular triglycerides were visualized by Oil red O staining, and the TLR4/myeloid differentiation primary response 88 (MyD88)/nuclear factor-κB (NF-κB) signaling cascade pathway were investigated. To directly elucidate whether TLR4 was the blocking target of celastrol upon FFA exposure, the cellular response to inflammation was determined upon transfection with TLR4 siRNA. The results revealed that celastrol significantly reduced triglyceride accumulation in the steatotic HepG2 cells, and downregulated the expression levels of TLR4, MyD88 and phospho-NF-κBp65, as well as of the downstream inflammatory cytokines interleukin-1β and tumor necrosis factor α. Knockdown of TLR4 also alleviated FFA-induced inflammatory response. In addition, co-treatment with TLR4 siRNA and celastrol further attenuated the expression of inflammatory mediators. These results suggest that celastrol exerts its protective effect partly via inhibiting the TLR4-mediated immune and inflammatory response in steatotic HepG2 cells.

Nonalcoholic Fatty Liver Disease and Diabetes Are Associated with Decreased CYP3A4 Protein Expression and Activity in Human Liver

Nonalcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease in the Western population. We investigated the association of nonalcoholic fatty liver disease (NAFLD) and diabetes mellitus on CYP3A4 activity in human liver tissue from brain dead donors ( n = 74). Histopathologically graded livers were grouped into normal ( n = 24), nonalcoholic fatty liver (NAFL, n = 26), and nonalcoholic steatohepatitis (NASH, n = 24) categories. The rate of conversion of midazolam to its 1-hydroxy metabolite was used to assess in vitro CYP3A4 activity in human liver microsomes (HLM). A proteomics approach was utilized to quantify the protein expression of CYP3A4 and related enzymes. Moreover, a physiologically based pharmacokinetic (PBPK) model was developed to allow prediction of midazolam concentration in NAFL and NASH livers. CYP3A4 activity in NAFL and NASH was 1.9- and 3.1-fold ( p < 0.05) lower than normal donors, respectively. Intrinsic clearance (CLint) was 2.7- ( p < 0.05) and 4.1-fold ( p < 0.01) lower in donors with NAFL and NASH, respectively. CYP3A4 protein expression was significantly lower in NAFL and NASH donors ( p < 0.05) and accounted for significant midazolam hydroxylation variability in a multiple linear regression analysis (β = 0.869, r² = 0.762, P < 0.01). Diabetes was also associated with decreased CYP3A4 activity and protein expression. Both midazolam CLint and CYP3A4 protein abundance decreased significantly with increase in hepatic fat accumulation. Age and gender did not exhibit any significant association with the observed alterations. Predicted midazolam exposure was 1.7- and 2.3-fold higher for NAFL and NASH, respectively, which may result in a longer period of sedation in these disease-states. Data suggests that NAFLD and diabetes are associated with the decreased hepatic CYP3A4 activity. Thus, further evaluation of clinical consequences of these findings on the efficacy and safety of CYP3A4 substrates is warranted.

Bitter melon extract ameliorates palmitate-induced apoptosis via inhibition of endoplasmic reticulum stress in HepG2 cells and high-fat/high-fructose-diet-induced fatty liver

Background

Bitter melon (BM) improves glucose level, lipid homeostasis, and insulin resistance in vivo. However, the preventive mechanism of BM in nonalcoholic fatty liver disease (NAFLD) has not been elucidated yet.

Aim & Design

To determine the protective mechanism of bitter melon extract (BME), we performed experiments in vitro and in vivo. BME were treated palmitate (PA)-administrated HepG2 cells. C57BL/6J mice were divided into two groups: high-fat/high-fructose (HF/HFr) without or with BME supplementation (100 mg/kg body weight). Endoplasmic reticulum (ER) stress, apoptosis, and biochemical markers were then examined by western blot and real-time PCR analyses.

Results

BME significantly decreased expression levels of ER-stress markers (including phospho-eIF2α, CHOP, and phospho-JNK [Jun N-terminal kinases]) in PA-treated HepG2 cells. BME also significantly decreased the activity of cleaved caspase-3 (a well known apoptotic-induced molecule) and DNA fragmentation. The effect of BME on ER stress-mediated apoptosis in vitro was similarly observed in HF/HFr-fed mice in vivo. BME significantly reduced HF/HFr-induced hepatic triglyceride (TG) and serum alanine aminotransferase (ALT) as markers of hepatic damage in mice. In addition, BME ameliorated HF/HFr-induced serum TG and serum-free fatty acids.

Conclusion

These data indicate that BME has protective effects against ER stress mediated apoptosis in HepG2 cells as well as in HF/HFr-induced fatty liver of mouse. Therefore, BME might be useful for preventing and treating NAFLD.

Key Inflammatory Processes in Human NASH Are Reflected in Ldlr-/-.Leiden Mice: A Translational Gene Profiling Study

Introduction: It is generally accepted that metabolic inflammation in the liver is an important driver of disease progression in NASH and associated matrix remodeling/fibrosis. However, the exact molecular inflammatory mechanisms are poorly defined in human studies. Investigation of key pathogenic mechanisms requires the use of pre-clinical models, for instance for time-resolved studies. Such models must reflect molecular disease processes of importance in patients. Herein we characterized inflammation in NASH patients on the molecular level by transcriptomics and investigated whether key human disease pathways can be recapitulated experimentally in Ldlr^−/−.Leiden mice, an established pre-clinical model of NASH.

Methods: Human molecular inflammatory processes were defined using a publicly available NASH gene expression profiling dataset (GSE48452) allowing the comparison of biopsy-confirmed NASH patients with normal controls. Gene profiling data from high-fat diet (HFD)-fed Ldlr^−/−.Leiden mice (GSE109345) were used for assessment of the translational value of these mice.

Results: In human NASH livers, we observed regulation of 65 canonical pathways of which the majority was involved in inflammation (32%), lipid metabolism (16%), and extracellular matrix/remodeling (12%). A similar distribution of pathways across these categories, inflammation (36%), lipid metabolism (24%) and extracellular matrix/remodeling (8%) was observed in HFD-fed Ldlr^−/−.Leiden mice. Detailed evaluation of these pathways revealed that a substantial proportion (11 out of 13) of human NASH inflammatory pathways was recapitulated in Ldlr^−/−.Leiden mice. Furthermore, the activation state of identified master regulators of inflammation (i.e., specific transcription factors, cytokines, and growth factors) in human NASH was largely reflected in Ldlr^−/−.Leiden mice, further substantiating its translational value.

Conclusion: Human NASH is characterized by upregulation of specific inflammatory processes (e.g., “Fcγ Receptor-mediated Phagocytosis in Macrophages and Monocytes,” “PI3K signaling in B Lymphocytes”) and master regulators (e.g., TNF, CSF2, TGFB1). The majority of these processes and regulators are modulated in the same direction in Ldlr^−/−.Leiden mice fed HFD with a human-like macronutrient composition, thus demonstrating that specific experimental conditions recapitulate human disease on the molecular level of disease pathways and upstream/master regulators.

Role of Inflammasomes in the Development of Gastrointestinal Diseases

Many diseases of the gastrointestinal tract have been attributed to chronic inflammation, and a few have identified the role of inflammasomes in their pathogenesis. Inflammasomes are a group of protein complexes comprising of several intracellular proteins that link the sensing of microbial products and metabolic stress to the proteolytic activation of the proinflammatory cytokines. Recent studies have implicated activation of several families of NOD-like receptors (NLRs) which are major components of inflammasomes in the development and exacerbation of many diseases of human systems. In this chapter, we discuss the role of inflammasomes in some of the most prevalent diseases of the gastrointestinal tract and highlight potential targets for treatment.

Mechanisms of the prevention and inhibition of the progression and development of non-alcoholic steatohepatitis by genetic and pharmacological decoy receptor 3 supplementation

AIMS

Treatment of non-alcoholic steatohepatitis (NASH) is difficult due to the absence of a proven treatment and its comprehensive mechanisms. In the NASH animal model, upregulated hepatic inflammation and oxidative stress, with the resultant M1 polarization of macrophages as well as imbalanced adipocytokines, all accelerate NASH progression. As a member of the tumor necrosis factor receptor superfamily, decoy receptor 3 (DcR3) not only neutralizes the death ligands, but also performs immune modulations. In this study, we aimed to investigate the possible non-decoy effects of DcR3 on diet-induced NASH mice.

METHODS

Methionine- and choline-deficient (MCD) diet feeding for 9 weeks was applied to induce NASH in BALB/c mice. Decoy receptor 3 heterozygous transgenesis or pharmacological pretreatment with DcR3a for 1 month were designed as interventions. Intrahepatic inflammatory status as well as macrophage polarization, oxidative stress, and steatosis as well as lipogenic gene expression and fibrotic status were analyzed. Additionally, acute effects of DcR3a on HepG2 cells, Hep3B cells, and primary mouse hepatocytes in various MCD medium-stimulated changes were also evaluated.

RESULTS

Both DcR3 genetic and pharmacologic supplement significantly reduced MCD diet-induced hepatic M1 polarization. In addition, DcR3 supplement attenuated MCD diet-increased hepatic inflammation, oxidative stress, adipocytokine imbalance, steatosis, and fibrogenesis. Moreover, acute DcR3a incubation in HepG2 cells, Hep3B cells, and mouse hepatocytes could normalize the expression of genes related to lipid oxidation along with inflammation and oxidative stress.

CONCLUSION

The ability of DcR3 to attenuate hepatic steatosis and inflammation through its non-decoy effects of immune modulation and oxidative stress attenuation makes it a potential treatment for NASH.