Mouse models in non-alcoholic fatty liver disease and steatohepatitis research

Glycoprotein nonmetastatic melanoma protein B is regulated by hepatic peroxisome proliferator-activated receptor γ in liver steatosis

Hepatic glycoprotein nonmetastatic melanoma protein B (GPNMB) and nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) play essential roles in lipid metabolism. This study aimed to examine the molecular mechanism through which PPARγ controls GPNMB expression in liver steatosis. A microarray database was used to examine the gene expression patterns associated with fatty liver in type 2 diabetic leptin-deficient (ob/ob) mice, as well as in patients with non-alcoholic fatty liver disease (NAFLD) and advanced NAFLD. GPNMB expression significantly increased in the fatty livers of humans and mice. Elevated Gpnmb expression was notably reduced by liver-specific Pparγ knockout (PPARγLKO) in ob/ob mice. Similarly, alcohol-fed mice had increased hepatic Gpnmb levels. Transcriptomic analysis of the human liver samples revealed that Gpnmb expression was markedly higher in patients with fatty liver diseases, including those with NAFLD and alcoholic fatty liver disease, than in controls. Reporter and electrophoretic mobility shift assays confirmed that PPARγ directly enhances Gpnmb transcription via three functional PPARγ-responsive elements within the first intron. In conclusion, these findings suggest that Gpnmb is a novel PPARγ target in liver steatosis.

A guide to pathophysiology, signaling pathways, and preclinical models of liver fibrosis

Liver fibrosis is potentially a reversible form of liver disease that evolved from the early stage of liver scarring as a consequence of chronic liver injuries. Recurrent injuries in the liver without any appropriate medication cause the injuries to get intense and deeper, which gradually leads to the progression of irreversible cirrhosis or carcinoma. Unfortunately, there are no approved treatment strategies for reversing hepatic fibrosis, making it one of the significant risk factors for developing advanced liver disorders and liver disease-associated mortality. Consequently, the interpretation of the fundamental mechanisms, etiology, and pathogenesis is crucial for identifying the potential therapeutic target as well as evaluating novel anti-fibrotic therapy. However, despite innumerable research, the functional mechanism and disease characteristics are still obscure. To accelerate the understanding of underlying disease pathophysiology, molecular pathways and disease progression mechanism, it is crucial to mimic human liver disease through the formation of precise disease models. Although various in vitro and in vivo liver fibrotic models have emerged and developed already, a perfect clinical model replicating human liver diseases is yet to be established, which is one of the major challenges in discovering proper therapeutics. This review paper will shed light on pathophysiology, signaling pathways, preclinical models of liver fibrosis, and their limitations.

Picrosides-rich fraction from Picrorhiza kurroa attenuates steatohepatitis in zebrafish and mice by modulating lipid metabolism and inflammation

BACKGROUND

Non-alcoholic steatohepatitis (NASH) has become a serious public health concern with high global prevalence. The lack of safe and efficient treatment for the condition demands exploring new therapeutic solutions.

PURPOSE

In the present study, we investigated the protective efficacy of picrosides-rich fraction (PF) from Picrorhiza kurroa against steatohepatitis and revealed the molecular mechanism of action.

METHODS

PF was prepared and characterized using UPLC analysis. Initially, the efficacy of PF was studied on the zebrafish model of NASH. Further, a Methionine and Choline-Deficient (MCD) diet-induced NASH model in mice was employed to evaluate the hepatoprotective efficacy of PF by utilizing biochemical, histopathological and molecular studies.

RESULTS

The UPLC analysis revealed the presence of 29.11% and 29.86% picroside I and II in the PF, respectively. In the zebrafish model of NASH, PF treatment reduced the hepatic lipid accumulation and modulated the expressions of lipogenic, inflammatory, oxidative, and cellular stress genes. Further, in MCD diet-induced NASH in mice, PF treatment showed a significant improvement in body weights and serum liver injury markers. Reduced degenerative changes and fibrous tissue was observed in the PF-treated groups. The downregulated expression of Srebp1c, Cd36, Fas, Chrebp, Pparγ, and Hnf4α showed anti-lipogenic potential of PF treatment. NASH development followed oxidative stress, mitochondrial dysfunction, and inflammation in the liver of mice. However, PF treatment encouraged mitochondrial biogenesis by upregulating Pgc1α, Tfam, and Nrf2 expressions. The elevated levels of NFκB, TNFα, IL6, TGFβ, and αSMA were also restored by PF, advocating its anti-inflammatory and anti-fibrogenic effect.

CONCLUSION

The present study revealed that PF ameliorate the progression of NASH by increasing mitochondrial biogenesis and decreasing lipogenesis, hepatic inflammation, and fibrosis.

TRIM21-mediated ubiquitination of SQSTM1/p62 abolishes its Ser403 phosphorylation and enhances palmitic acid cytotoxicity

Long-chain free fatty acids (FFAs) accumulation and oxidative toxicity is a major cause for several pathological conditions. The mechanisms underlying FFA cytotoxicity remain elusive. Here we show that palmitic acid (PA), the most abundant FFA in the circulation, induces S403 phosphorylation of SQSTM1/p62 (sequestosome 1) and its aggregation, which sequesters KEAP1 and activates the non-canonical SQSTM1-KEAP1-NFE2L2 antioxidant pathway. The PA-induced SQSTM1 S403 phosphorylation and aggregation are dependent on SQSTM1 K7-D69 hydrogen bond formation and dimerization in the Phox and Bem1 (PB1) domain, which facilitates the recruitment of TBK1 that phosphorylates SQSTM1 S403. The ubiquitin E3 ligase TRIM21 ubiquitinates SQSTM1 at the K7 residue and abolishes the PB1 dimerization, S403 phosphorylation, and SQSTM1 aggregation. TRIM21 is oxidized at C92, C111, and C114 to form disulfide bonds that lead to its oligomerization and decreased E3 activity. Mutagenizing the three C residues to S (3CS) abolishes TRIM21 oligomerization and increases its E3 activity. TRIM21 ablation leads to decreased SQSTM1 K7 ubiquitination, hence elevated SQSTM1 S403 phosphorylation and aggregation, which confers protection against PA-induced oxidative stress and cytotoxicity. Therefore, TRIM21 is a negative regulator of SQSTM1 phosphorylation, aggregation, and the antioxidant sequestration function. TRIM21 is oxidized to reduce its E3 activity that helps enhance the SQSTM1-KEAP1-NFE2L2 antioxidant pathway. Inhibition of TRIM21 May be a viable strategy to protect tissues from lipotoxicity resulting from long-chain FFAs.Abbreviations: ER: endoplasmic reticulum; FFA: free fatty acid; HMOX1/HO-1: heme oxygenase 1; IB: immunoblotting; IF: immunofluorescence; IP: immunoprecipitation; KEAP1: kelch like ECH associated protein 1; MASH: metabolic dysfunction-associated steatohepatitis; MEF: mouse embryonic fibroblast; NFE2L2/Nrf2: NFE2 like BZIP transcription factor 2; PA: palmitic acid; PB1: Phox and Bem 1; ROS: reactive oxygen species; SLD: steatotic liver disease; SQSTM1: sequestosome 1; TBK1: TANK-binding kinase 1; TRIM21: tripartite motif containing 21.

The Effect of Quercetin on Non-Alcoholic Fatty Liver Disease (NAFLD) and the Role of Beclin1, P62, and LC3: An Experimental Study

Background/Objectives: Non-alcoholic fatty liver disease (NAFLD) is a major metabolic disorder with no established pharmacotherapy. Quercetin, a polyphenolic flavonoid, demonstrates potential hepatoprotective effects but has limited bioavailability. This study evaluates the impact of quercetin on NAFLD and assesses the roles of autophagy-related proteins in disease progression. Methods: Forty-seven male C57BL/6J mice were fed a high-fat diet (HFD) for 12 weeks to induce NAFLD, followed by quercetin treatment for 4 weeks. Mice were divided into baseline, control, and two quercetin groups, receiving low (10 mg/kg) and high (50 mg/kg) doses. Liver histology was scored using the NAFLD Activity Score (NAS). Immunohistochemistry and immunoblotting were performed to analyze autophagy markers. Results: Quercetin-treated groups showed significant reductions in NAS compared to controls (p = 0.011), mainly in steatosis and steatohepatitis. Immunohistochemistry indicated increased expression of autophagy markers LCA and p62 in quercetin groups. Western blot analysis revealed significant elevations in LC3A in the treated groups, suggesting improved autophagic activity and lipid degradation. Conclusions: Quercetin effectively reduces NAFLD severity and modulates autophagy-related proteins. These findings suggest that quercetin enhances autophagic flux, supporting its therapeutic potential for NAFLD. Additional research is needed to clarify the molecular mechanisms of quercetin and to determine the optimal dosing for clinical application.

Transmembrane and coiled-coil domain family 3 gene is a novel target of hepatic peroxisome proliferator-activated receptor γ in fatty liver disease

The peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor abundantly expressed in the nonalcoholic fatty liver disease (NAFLD). In this study, we investigated the mechanism by which PPARγ regulates the transmembrane and coiled-coil domain family 3 (Tmcc3) gene in the liver. We found that TMCC3 is highly expressed in the fatty liver of humans and mice with NAFLD and alcoholic fatty liver disease. Three exon 1 variants (Tmcc3-1a, -1b, and -1c) of mouse Tmcc3 were identified. TMCC3-1B was highly expressed in the fatty liver of type 2 diabetic ob/ob mice; however, this increase in expression was ameliorated by liver-specific knockout of PPARγ. Reporter assays and electrophoretic mobility shift assays showed that PPARγ positively regulates Tmcc3-1b and -1c transcription through the same PPARγ-responsive element present in the 5'-region of each Tmcc3. Altogether, our results indicate that Tmcc3 is a novel PPARγ target in the fatty liver disease.

Loss of MER Tyrosine Kinase Attenuates Adipocyte Hypertrophy and Leads to Enhanced Thermogenesis in Mice Exposed to High-Fat Diet

Obesity is characterized by low-grade inflammation that originates predominantly from the expanding visceral adipose tissue, in which adipocytes respond to lipid overload with hypertrophy, and consequently die by apoptosis. Recruited adipose tissue macrophages (ATMs) take up the excess lipids and remove the dead cells; however, long-term exposure to high concentrations of lipids alters their phenotype to M1-like ATMs that produce pro-inflammatory cytokines and resistin leading to insulin resistance and other obesity-related pathologies. Mer tyrosine kinase is expressed by macrophages and by being an efferocytosis receptor, and by suppressing inflammation, we hypothesized that it might play a protective role against obesity. To our surprise, however, the loss of Mer protected mice against high-fat diet (HFD)-induced obesity. We report in this paper that Mer is also expressed by adipocytes of both white and brown adipose tissues, and while its activity facilitates adipocyte lipid storage both in vitro and in vivo in mice exposed to HFD, it simultaneously attenuates thermogenesis in the brown adipose tissue contributing to its 'whitening'. Our data indicate that Mer is one of the adipocyte tyrosine kinase receptors, the activity of which contributes to the metabolic decision about the fate of excess lipids favoring their storage within the body.

Quercetin's Potential in MASLD: Investigating the Role of Autophagy and Key Molecular Pathways in Liver Steatosis and Inflammation

Metabolic dysfunction-associated fatty liver disease (MASLD) is a widespread liver disorder characterized by excessive fat accumulation in the liver, commonly associated with metabolic syndrome components such as obesity, diabetes, and dyslipidemia. With a global prevalence of up to 30%, MASLD is projected to affect over 100 million people in the U.S. and 20 million in Europe by 2030. The disease ranges from Steatotic Lived Disease (SLD) to more severe forms like metabolic dysfunction-associated steatohepatitis (MASH), which can progress to cirrhosis and hepatocellular carcinoma. Autophagy, a cellular process crucial for lipid metabolism and homeostasis, is often impaired in MASLD, leading to increased hepatic lipid accumulation and inflammation. Key autophagy-related proteins, such as Beclin1, LC3A, SQSTM1 (p62), CD36, and Perilipin 3, play significant roles in regulating this process. Disruption in these proteins contributes to the pathogenesis of MASLD. Quercetin, a natural polyphenolic flavonoid with antioxidant and anti-inflammatory properties, has promising results in mitigating MASLD. It may reduce hepatic lipid accumulation, improve mitochondrial function, and enhance autophagy. However, further research is needed to elucidate its mechanisms and validate its therapeutic potential in clinical settings. This underscores the need for continued investigation into autophagy and novel treatments for MASLD.

Investigating the tamoxifen/high-fat diet synergy: a promising paradigm for nonalcoholic steatohepatitis induction in a rat model

Non-alcoholic steatohepatitis (NASH) is a severe liver condition characterized by excessive fat deposition, ballooning, and lobular inflammation. This investigation was conducted to estimate the capability of concomitant tamoxifen administration (TAM) with a high fat diet (HFD) to induce a reliable NASH model that mimics human NASH features. Rats were administered TAM (25 mg/kg/day p.o.) and consumed HFD for 5 weeks. A time-course investigation was conducted to determine the optimal time for NASH development. Liver function indices, hepatic lipid profile factors, oxidative stress biomarkers, and inflammatory mediators were estimated. Additionally, macroscopic and microscopic changes were examined. Compared with the time-matched control group receiving vehicle alone, TAM/HFD significantly impaired liver function indices represented as marked elevation in ALT, AST, and ALP serum levels. TAM/HFD significantly increased lipid profile factors including high TG and TC hepatic levels. Additionally, TAM/HFD remarkably raised hepatic levels of TNF-α and IL-17 and significantly decreased IL-10. The combination also increases the oxidative status evidenced by high content of MDA as well as low activity of GPx and SOD. Accordingly, the combination of TAM and HFD for 5 weeks collaboratively promotes NASH development by initiating compromised hepatocyte functionality, elevated lipid levels, oxidative stress, and liver inflammation.

A Scoping Review on Hepatoprotective Mechanism of Herbal Preparations through Gut Microbiota Modulation

Liver diseases cause millions of deaths globally. Current treatments are often limited in effectiveness and availability, driving the search for alternatives. Herbal preparations offer potential hepatoprotective properties. Disrupted gut microbiota is linked to liver disorders. This scoping review aims to explore the effects of herbal preparations on hepatoprotective mechanisms, particularly in the context of non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), and hepatic steatosis, with a focus on gut microbiota modulation. A systematic search was performed using predetermined keywords in four electronic databases (PubMed, Scopus, EMBASE, and Web of Science). A total of 55 studies were included for descriptive analysis, covering study characteristics such as disease model, dietary model, animal model, intervention details, comparators, and study outcomes. The findings of this review suggest that the hepatoprotective effects of herbal preparations are closely related to their interactions with the gut microbiota. The hepatoprotective mechanisms of herbal preparations are shown through their effects on the gut microbiota composition, intestinal barrier, and microbial metabolites, which resulted in decreased serum levels of liver enzymes and lipids, improved liver pathology, inhibition of hepatic fatty acid accumulation, suppression of inflammation and oxidative stress, reduced insulin resistance, and altered bile acid metabolism.

miR-21: A therapeutic target for delaying severe liver disease and hepatocellular carcinoma in high-fat-diet-fed mice

Liver disease, including hepatocellular carcinoma (HCC), is a major global health concern, claiming approximately 2 million lives worldwide annually, yet curative treatments remain elusive. In this study, we aimed to investigate the role of microRNA-21-5p (miR-21) in metabolic dysfunction-associated steatotic liver disease (previously NAFLD), metabolic-associated steatohepatitis (previously NASH), and HCC within the context of a Western high-fat diet, without additional choline (HFD) and offering potential therapeutic insights. We found that reduced miR-21 levels correlated with liver disease progression in WT mice fed on HFD, while miR-21 knockout mice showed exacerbated metabolic dysfunction, including obesity, hepatomegaly, hyperglycemia, insulin resistance, steatosis, fibrosis, and HCC. Our study reveals that miR-21 plays a protective role in metabolic syndrome and in the progression of liver disease to cancer. MiR-21 directly targets Transforming growth factor beta-induced (Tgfbi), a gene also known to be significantly upregulated and a potential oncogene in HCC. Further, our study showed that intervention with the administration of a miR-21 mimic in WT livers effectively improves insulin sensitivity, steatosis, fibrosis, Tgfbi expression and tumor burden in HFD conditions. These findings indicate that miR-21 could serve as an effective strategy to delay or prevent liver disease in high-fat-diet environments.

Determination of Choline-Containing Compounds in Rice Bran Fermented with Aspergillus oryzae Using Liquid Chromatography/Tandem Mass Spectrometry

Choline-containing compounds are essential nutrients for human activity, as they are involved in many biological processes, including cell membrane organization, methyl group donation, neurotransmission, signal transduction, lipid transport, and metabolism. These compounds are normally obtained from food. Fermented brown rice and rice bran with Aspergillus oryzae (FBRA) is a fermented food product derived from rice and rice ingredients. FBRA exhibits a multitude of functional properties with respect to the health sciences. This study has a particular focus on choline-containing compounds. We first developed a simultaneous liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis method for seven choline-containing compounds. The method was subsequently applied to FBRA and its ingredients. Hydrophilic interaction chromatography (HILIC) and selected reaction monitoring were employed for the simultaneous analysis of seven choline-containing compounds. MS ion source conditions were optimized in positive ion mode, and the product ions derived from the choline group were obtained through MS/MS optimization. Under optimized HILIC conditions, the peaks exhibited good shape without peak tailing. Calibration curves demonstrated high linearity across a 300- to 10,000-fold concentration range. The application of the method to FBRA and other ingredients revealed significant differences between food with and without fermentation. In particular, betaine and α-glycerophosphocholine were found to be highest in FBRA and brown rice malt, respectively. The results indicated that the fermentation processing of rice ingredients results in alterations to the choline-containing compounds present in foods. The developed HILIC/MS/MS method proved to be a valuable tool for elucidating the composition of choline-containing compounds in foods.

The Effects of Long-Term High Fat and/or High Sugar Feeding on Sources of Postprandial Hepatic Glycogen and Triglyceride Synthesis in Mice

BACKGROUND

In MASLD (formerly called NAFLD) mouse models, oversupply of dietary fat and sugar is more lipogenic than either nutrient alone. Fatty acids suppress de novo lipogenesis (DNL) from sugars, while DNL inhibits fatty acid oxidation. How such factors interact to impact hepatic triglyceride levels are incompletely understood.

METHODS

Using deuterated water, we measured DNL in mice fed 18-weeks with standard chow (SC), SC supplemented with 55/45-fructose/glucose in the drinking water at 30% (w/v) (HS), high-fat chow (HF), and HF with HS supplementation (HFHS). Liver glycogen levels and its sources were also measured. For HS and HFHS mice, pentose phosphate (PP) fluxes and fructose contributions to DNL and glycogen were measured using [U-13C]fructose.

RESULTS

The lipogenic diets caused significantly higher liver triglyceride levels compared to SC. DNL rates were suppressed in HF compared to SC and were partially restored in HFHS but supplied a minority of the additional triglyceride in HFHS compared to HF. Fructose contributed a significantly greater fraction of newly synthesized saturated fatty acids compared to oleic acid in both HS and HFHS. Glycogen levels were not different between diets, but significant differences in Direct and Indirect pathway contributions to glycogen synthesis were found. PP fluxes were similar in HS and HFHS mice and were insufficient to account for DNL reducing equivalents.

CONCLUSIONS

Despite amplifying the lipogenic effects of fat, the fact that sugar-activated DNL per se barely contributes suggests that its role is likely more relevant in the inhibition of fatty acid oxidation. Fructose promotes lipogenesis of saturated over unsaturated fatty acids and contributes to maintenance of glycogen levels. PP fluxes associated with sugar conversion to fat account for a minor fraction of DNL reducing equivalents.

An unbiased ranking of murine dietary models based on their proximity to human metabolic dysfunction-associated steatotic liver disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease, encompasses steatosis and metabolic dysfunction-associated steatohepatitis (MASH), leading to cirrhosis and hepatocellular carcinoma. Preclinical MASLD research is mainly performed in rodents; however, the model that best recapitulates human disease is yet to be defined. We conducted a wide-ranging retrospective review (metabolic phenotype, liver histopathology, transcriptome benchmarked against humans) of murine models (mostly male) and ranked them using an unbiased MASLD 'human proximity score' to define their metabolic relevance and ability to induce MASH-fibrosis. Here, we show that Western diets align closely with human MASH; high cholesterol content, extended study duration and/or genetic manipulation of disease-promoting pathways are required to intensify liver damage and accelerate significant (F2+) fibrosis development. Choline-deficient models rapidly induce MASH-fibrosis while showing relatively poor translatability. Our ranking of commonly used MASLD models, based on their proximity to human MASLD, helps with the selection of appropriate in vivo models to accelerate preclinical research.

Afriplex GRTTM extract attenuates hepatic steatosis in an in vitro model of NAFLD

BACKGROUND

Currently, it is acknowledged that vitamin E, insulin sensitizers and anti-diabetic drugs are used to manage non-alcoholic fatty liver disease (NAFLD), however, these therapeutic interventions harbour adverse side effects. Pioglitazone, an anti-diabetic drug, is currently the most effective therapy to manage NAFLD. The use of natural medicines is widely embraced due to the lack of evidence of their negative side effects. Rooibos has been previously shown to decrease inflammation and oxidative stress in experimental models of diabetes, however, this is yet to be explored in a setting of NAFLD. This study was aimed at investigating the effects of an aspalathin-rich green rooibos extract (Afriplex GRTTM) against markers of hepatic oxidative stress, inflammation and apoptosis in an in vitro model of NAFLD.

METHODS

Oleic acid [1 mM] was used to induce hepatic steatosis in C3A liver cells. Thereafter, the therapeutic effect of Afriplex GRTTM, with or without pioglitazone, was determined by assessing its impact on cell viability, changes in mitochondrial membrane potential, intracellular lipid accumulation and the expression of genes and proteins (ChREBP, SREBF1, FASN, IRS1, SOD2, Caspase-3, GSTZ1, IRS1 and TNF-α) that are associated with the development of NAFLD.

RESULTS

Key findings showed that Afriplex GRTTM added to the medium alone or combined with pioglitazone, could effectively block hepatic lipid accumulation without inducing cytotoxicity in C3A liver cells exposed oleic acid. This positive outcome was consistent with effective regulation of genes involved in insulin signaling, as well as carbohydrate and lipid metabolism (IRS1, SREBF1 and ChREBP). Interestingly, in addition to reducing protein levels of an inflammatory marker (TNF-α), the Afriplex GRTTM could ameliorate oleic acid-induced hepatic steatotic damage by decreasing the protein expression of oxidative stress and apoptosis related markers such as GSTZ1 and caspase-3.

CONCLUSION

Afriplex GRTTM reduced hepatic steatosis in oleic acid induced C3A liver cells by modulating SREBF1, ChREBP and IRS-1 gene expression. The extract may also play a role in alleviating inflammation by reducing TNF-α expression, suggesting that additional experiments are required for its development as a suitable therapeutic option against NAFLD. Importantly, further research is needed to explore its antioxidant role in this model.

Apical papilla stem cell-derived exosomes regulate lipid metabolism and alleviate inflammation in the MCD-induced mouse NASH model

Stem cells from the apical papilla(SCAPs) exhibit remarkable tissue repair capabilities, demonstrate anti-inflammatory and pro-angiogenic effects, positioning them as promising assets in the realm of regenerative medicine. Recently, the focus has shifted towards exosomes derived from stem cells, perceived as safer alternatives while retaining comparable physiological functions. This study delves into the therapeutic implications of exosomes derived from SCAPs in the methionine-choline-deficient (MCD) diet-induced mice non-alcoholic steatohepatitis (NASH) model. We extracted exosomes from SCAPs. During the last two weeks of the MCD diet, mice were intravenously administered SCAPs-derived exosomes at two distinct concentrations (50 μg/mouse and 100 μg/mouse) biweekly. Thorough examinations of physiological and biochemical indicators were performed to meticulously evaluate the impact of exosomes derived from SCAPs on the advancement of NASH in mice induced by MCD diet. This findings revealed significant reductions in body weight loss and liver damage induced by the MCD diet following exosomes treatment. Moreover, hepatic fat accumulation was notably alleviated. Mechanistically, the treatment with exosomes led to an upregulation of phosphorylated adenosine monophosphate-activated protein kinase (p-AMPK) levels in the liver, enhancing hepatic fatty acid oxidation and transporter gene expression while inhibiting genes associated with fatty acid synthesis. Additionally, exosomes treatment increased the transcription levels of key liver mitochondrial marker proteins and the essential mitochondrial biogenesis factor. Furthermore, the levels of serum inflammatory factors and hepatic tissue inflammatory factor mRNA expression were significantly reduced, likely due to the anti-inflammatory phenotype induced by exosomes in macrophages. The above conclusion suggests that SCAPs-exosomes can improve NASH.

Effectiveness of metformin for the reversal of cold-ischemia-induced damage in hepatosteatosis

BACKGROUND

Primary dysfunction and rejection are more common in donor liver tissues with steatosis. AMP-activated protein kinase (AMPK) assumes organ-protective functions during ischemia. Metformin was used for the activation of AMPK in hepatocytes. The aim of this study is to investigate the effectiveness of metformin administration for the reversal of cold-ischemia-induced damage in hepatosteatosis.

MATERIAL AND METHODS

Seven-week-old C7BL56 male-mice (n = 109) were separated into four groups depending on diet type and metformin use. A specific diet model was followed for 10 weeks to induce hepatosteatosis. A group of the animals was administered with metformin for the last four weeks via oral gavage. After resection, the liver tissues were perfused and kept for 0-6-12-24 h in the UW solution. Histopathological examinations were performed, and Western blot was utilized to analyze p-AMPK and AMPK expression levels.

RESULTS

Hepatosteatosis decreased significantly with metformin. The steatotic liver group had more prominent pericentral inflammation, necrosis as well as showing a decreased and more delayed AMPK response than the non-fat group. All these alterations could be corrected using metformin.

CONCLUSION

Metformin can increase the resistance of livers with hepatosteatosis to cold-ischemia-induced damage, which in turn may pave the way for successful transplantation of fatty living-donor livers.

Impact of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) on the expression and function of hepatobiliary transporters: A comprehensive mechanistic review

The liver plays a central role in the biotransformation and disposition of endogenous molecules and xenobiotics. In addition to drug-metabolizing enzymes, transporter proteins are key determinants of drug hepatic clearance. Hepatic transporters are transmembrane proteins that facilitate the movement of chemicals between sinusoidal blood and hepatocytes. Other drug transporters translocate molecules from hepatocytes into bile canaliculi for biliary excretion. The formers are known as basolateral, while the latter are known as canalicular transporters. Also, these transporters are classified into two super-families, the solute carrier transporter (SLC) and the adenosine triphosphate (ATP)-binding cassette (ABC) transporter. The expression and function of transporters involve complex regulatory mechanisms, which are contributing factors to interindividual variability in drug pharmacokinetics and disposition. A considerable number of liver diseases are known to alter the expression and function of drug transporters. Among them, non-alcoholic fatty liver disease (NAFLD) is a chronic condition with a rapidly increasing incidence worldwide. NAFLD, recently reclassified as metabolic dysfunction-associated steatotic liver disease (MASLD), is a disease continuum that includes steatosis with or without mild inflammation (NASH), and potentially neuroinflammatory pathology. NASH is additionally characterized by the presence of hepatocellular injury. During NAFLD and NASH, drug transporters exhibit altered expression and function, leading to altered drug pharmacokinetics and pharmacodynamics, thus increasing the risk of adverse drug reactions. The purpose of the present review is to provide comprehensive mechanistic information on the expression and function of hepatic transporters under fatty liver conditions and hence, the impact on the pharmacokinetic profiles of certain drugs from the available pre-clinical and clinical literature.

Embryonic Amoxicillin Exposure Has Limited Impact on Liver Development but Increases Susceptibility to NAFLD in Zebrafish Larvae

Amoxicillin is commonly used in clinical settings to target bacterial infection and is frequently prescribed during pregnancy. Investigations into its developmental toxicity and effects on disease susceptibility are not comprehensive. Our present study examined the effects of embryonic amoxicillin exposure on liver development and function, especially the effects on susceptibility to non-alcoholic fatty liver disease (NAFLD) using zebrafish as an animal model. We discovered that embryonic amoxicillin exposure did not compromise liver development, nor did it induce liver toxicity. However, co-treatment of amoxicillin and clavulanic acid diminished BESP expression, caused bile stasis and induced liver toxicity. Embryonic amoxicillin exposure resulted in elevated expression of lipid synthesis genes and exacerbated hepatic steatosis in a fructose-induced NAFLD model, indicating embryonic amoxicillin exposure increased susceptibility to NAFLD in zebrafish larvae. In summary, this research broadens our understanding of the risks of amoxicillin usage during pregnancy and provides evidence for the impact of embryonic amoxicillin exposure on disease susceptibility in offspring.

Non-alcoholic fatty liver disease: pathogenesis and models

Non-alcoholic fatty liver disease (NAFLD) is a complex disease characterized by a massive accumulation of lipids in the liver, with a continuous progression of simple steatosis, non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma. Non-alcoholic fatty liver disease is associated with obesity, insulin resistance, and metabolic syndrome; it is a severe public health risk and is currently the most common liver disease of the world. In addition to the fatty infiltration of the liver in non-alcoholic fatty liver disease patients, the field of liver transplantation faces similar obstacles. NAFLD and NASH primarily involve lipotoxicity, inflammation, oxidative stress, and insulin resistance. However, the precise mechanisms and treatments remain unclear. Therapeutic approaches encompass exercise, weight control, as well as treatments targeting antioxidants and anti-inflammatory pathways. The role of animal models in research has become crucial as a key tool to explore the molecular mechanisms and potential treatments for non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. Here, we summarized the current understanding of the pathogenesis of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis and discussed animal models commonly used in recent years.

Vascular endothelial cell-specific overexpression of CNP did not improve liver fibrosis in HFFCD-induced NASH, but did improve renal lesions

Mice with endothelial-cell-specific overexpression of C-type natriuretic peptide (E-CNP Tg mice) were shown to be protected against hepatic fibrosis and inflammation induced by high fat diet (HFD) feeding, with improved insulin sensitivity and attenuated weight gain. A recently developed high-fat, high-fructose, high-cholesterol diet (HFFCD) is considered to be a superior model to HFD, owing to the resemblance to human non-alcoholic steatohepatitis (NASH). In this study, we therefore aimed to reveal whether these previous findings with E-CNP Tg mice on HFD can be observed in a newly developed NASH model.　Patients with NASH have been suggested to be at higher risk of developing chronic kidney disease, so we also assessed the kidney histology of these mice. After 8 months of HFFCD feeding, the livers of E-CNP Tg mice and controls showed progressive fibrosis, which resembled the features of human NASH. However, no significant differences were observed in NAFLD activity scores between E-CNP Tg mice and controls, although there was a tendency for improvement in E-CNP Tg mice. The reduced levels of GCB, a receptor for CNP, may have weakened the action of CNP in the current model. In the kidneys, HFFCD showed glomerular hypertrophy and tubular atrophy in the cortical region, which were suppressed in E-CNP Tg mice. The present study did not prove the therapeutic effect of CNP on NASH in the HFFCD model, but provided evidence of its potential beneficial effects on NASH-associated renal damage.

Maternal undernutrition results in transcript changes in male offspring that may promote resistance to high fat diet induced weight gain

Maternal nutrition during embryonic development and lactation influences multiple aspects of offspring health. Using mice, this study investigates the effects of maternal caloric restriction (CR) during mid-gestation and lactation on offspring neonatal development and on adult metabolic function when challenged by a high fat diet (HFD). The CR maternal model produced male and female offspring that were significantly smaller, in terms of weight and length, and females had delayed puberty. Adult offspring born to CR dams had a sexually dimorphic response to the high fat diet. Compared to offspring of maternal control dams, adult female, but not male, CR offspring gained more weight in response to high fat diet at 10 weeks. In adipose tissue of male HFD offspring, maternal undernutrition resulted in blunted expression of genes associated with weight gain and increased expression of genes that protect against weight gain. Regardless of maternal nutrition status, HFD male offspring showed increased expression of genes associated with progression toward nonalcoholic fatty liver disease (NAFLD). Furthermore, we observed significant, sexually dimorphic differences in serum TSH. These data reveal tissue- and sex-specific changes in gene and hormone regulation following mild maternal undernutrition, which may offer protection against diet induced weight gain in adult male offspring.

Graphislactone A, a Fungal Antioxidant Metabolite, Reduces Lipogenesis and Protects against Diet-Induced Hepatic Steatosis in Mice

Graphislactone A (GPA), a secondary metabolite derived from a mycobiont found in the lichens of the genus Graphis, exhibits antioxidant properties. However, the potential biological functions and therapeutic applications of GPA at the cellular and animal levels have not yet been investigated. In the present study, we explored the therapeutic potential of GPA in mitigating non-alcoholic fatty liver disease (NAFLD) and its underlying mechanisms through a series of experiments using various cell lines and animal models. GPA demonstrated antioxidant capacity on a par with that of vitamin C in cultured hepatocytes and reduced the inflammatory response induced by lipopolysaccharide in primary macrophages. However, in animal studies using an NAFLD mouse model, GPA had a milder impact on liver inflammation while markedly attenuating hepatic steatosis. This effect was confirmed in an animal model of early fatty liver disease without inflammation. Mechanistically, GPA inhibited lipogenesis rather than fat oxidation in cultured hepatocytes. Similarly, RNA sequencing data revealed intriguing associations between GPA and the adipogenic pathways during adipocyte differentiation. GPA effectively reduced lipid accumulation and suppressed lipogenic gene expression in AML12 hepatocytes and 3T3-L1 adipocytes. In summary, our study demonstrates the potential application of GPA to protect against hepatic steatosis in vivo and suggests a novel role for GPA as an underlying mechanism in lipogenesis, paving the way for future exploration of its therapeutic potential.

Identification and validation of key biomarkers associated with macrophages in nonalcoholic fatty liver disease based on hdWGCNA and machine learning

BACKGROUND

NAFLD has attracted increasing attention because of its high prevalence and risk of progression to cirrhosis or even hepatocellular carcinoma. Therefore, research into the root causes and molecular indicators of NAFLD is crucial.

METHODS

We analyzed scRNA-seq data and RNA-seq data from normal and NAFLD liver samples. We utilized hdWGCNA to find module-related genes associated with the phenotype. Multiple machine learning algorithms were used to validate the model diagnostics and further screen for genes that are characteristic of NAFLD. The NAFLD mouse model was constructed using the MCD diet to validate the diagnostic effect of the genes.

RESULTS

We identified a specific macrophage population called NASH-macrophages by single-cell sequencing analysis. Cell communication analysis and Pseudo-time trajectory analysis revealed the specific role and temporal distribution of NASH-macrophages in NAFLD. The hdWGCNA screening yielded 30 genes associated with NASH-macrophages, and machine learning algorithms screened and obtained two genes characterizing NAFLD. The immune infiltration indicated that these genes were highly associated with macrophages. Notably, we verified by RT-qPCR, IHC, and WB that MAFB and CX3CR1 are highly expressed in the MCD mouse model and may play important roles.

CONCLUSIONS

Our study revealed a macrophage population that is closely associated with NAFLD. Using hdWGCNA analysis and multiple machine learning algorithms, we identified two NAFLD signature genes that are highly correlated with macrophages. Our findings may provide potential feature markers and therapeutic targets for NAFLD.

Nobiletin Ameliorates Hepatic Lipid Deposition, Oxidative Stress, and Inflammation by Mechanisms That Involve the Nrf2/NF-κB Axis in Nonalcoholic Fatty Liver Disease

Nobiletin (NOB), a flavonoid with significant antioxidant potential, holds promise for treating nonalcoholic fatty liver disease (NAFLD). In this work, we aim to assess the effects and investigate the molecular mechanisms of NOB on NAFLD. After using a methionine choline-deficient diet to induce C57BL/6J mice, as well as oleic acid to induce HepG2 and L02 cells, we administered NOB as an intervention. The results indicated that the NOB significantly ameliorated lipid deposition, oxidative stress, and inflammation in NAFLD in both models. Its mechanism may involve the Nrf2, SREBP-1c, and NF-κB signaling pathways. Furthermore, Nrf2 is not only a direct target for NOB to improve oxidative damage but also indirectly involved in lipid-lowering and anti-inflammatory processes in NAFLD. By inhibiting Nrf2, we found that the regulatory role of Nrf2 in lipid metabolism is not related to SREBP-1c but is closely associated with NF-κB in terms of inflammation. Our results suggest that Nrf2 is one of the most critical targets for NOB against NAFLD in multiple aspects.

The Ameliorating Effects of n-3 Polyunsaturated Fatty Acids on Liver Steatosis Induced by a High-Fat Methionine Choline-Deficient Diet in Mice

The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is associated with abnormalities of liver lipid metabolism. On the contrary, a diet enriched with n-3 polyunsaturated fatty acids (n-3-PUFAs) has been reported to ameliorate the progression of NAFLD. The aim of our study was to investigate the impact of dietary n-3-PUFA enrichment on the development of NAFLD and liver lipidome. Mice were fed for 6 weeks either a high-fat methionine choline-deficient diet (MCD) or standard chow with or without n-3-PUFAs. Liver histology, serum biochemistry, detailed plasma and liver lipidomic analyses, and genome-wide transcriptome analysis were performed. Mice fed an MCD developed histopathological changes characteristic of NAFLD, and these changes were ameliorated with n-3-PUFAs. Simultaneously, n-3-PUFAs decreased serum triacylglycerol and cholesterol concentrations as well as ALT and AST activities. N-3-PUFAs decreased serum concentrations of saturated and monounsaturated free fatty acids (FAs), while increasing serum concentrations of long-chain PUFAs. Furthermore, in the liver, the MCD significantly increased the hepatic triacylglycerol content, while the administration of n-3-PUFAs eliminated this effect. Administration of n-3-PUFAs led to significant beneficial differences in gene expression within biosynthetic pathways of cholesterol, FAs, and pro-inflammatory cytokines (IL-1 and TNF-α). To conclude, n-3-PUFA supplementation appears to represent a promising nutraceutical approach for the restoration of abnormalities in liver lipid metabolism and the prevention and treatment of NAFLD.

Effects of lysolecithins on performance, egg quality, blood profiles and liver histopathology in late-phase laying hens

1. This study investigated the effects of lysolecithins (LL) on performance, egg quality, blood profiles, relative organ weight and liver histopathology in laying hens.2. A total of 480 healthy 65-week-old Lohmann laying hens were randomly allocated into four treatments in a 2 × 2 factorial arrangement design with two levels of energy (AMEn, 11.08 MJ/kg and 12.94 MJ/kg) and two levels of LL (0 and 0.05%).3. Birds fed high energy diets had lower (P < 0.05) average daily intake and feed conversion rate during weeks 0-4, 5-8 and 0-8, but higher (P < 0.05) average egg weight (AEW) during trial weeks 0-4. There was an interaction in (P < 0.05) AEW during trial weeks 0-14 and 0-8 for energy and LL. The high energy diets increased yolk colour at the end of weeks 2 and 4, while addition of LL increased albumen height at the end of week 2. There was an interaction (P < 0.05) in yolk colour between energy and LL at the end of week 2. There was an interaction (P < 0.05) in serum superoxide dismutase and LDL-C throughout the experiment.4. The high energy diets increased (P < 0.05) the relative weight of abdominal fat compared with low energy diets. The high energy diets increased (P < 0.05) liver ether extract content and liver pathological injury score compared with low energy diets at the end of week 8, while the addition of LL decreased (P < 0.05) liver pathological injury score.5. The supplementation of LL in high energy diets could alleviate some negative effects on liver injury in late laying hens.

Thermoneutral Housing Enables Studies of Vertical Transmission of Obesogenic Diet-Driven Metabolic Diseases

Vertical transmission of obesity is a critical contributor to the unabated obesity pandemic and the associated surge in metabolic diseases. Existing experimental models insufficiently recapitulate "human-like" obesity phenotypes, limiting the discovery of how severe obesity in pregnancy instructs vertical transmission of obesity. Here, via utility of thermoneutral housing and obesogenic diet feeding coupled to syngeneic mating of WT obese female and lean male mice on a C57BL/6 background, we present a tractable, more "human-like" approach to specifically investigate how maternal obesity contributes to offspring health. Using this model, we found that maternal obesity decreased neonatal survival, increased offspring adiposity, and accelerated offspring predisposition to obesity and metabolic disease. We also show that severe maternal obesity was sufficient to skew offspring microbiome and create a proinflammatory gestational environment that correlated with inflammatory changes in the offspring in utero and adulthood. Analysis of a human birth cohort study of mothers with and without obesity and their infants was consistent with mouse study findings of maternal inflammation and offspring weight gain propensity. Together, our results show that dietary induction of obesity in female mice coupled to thermoneutral housing can be used for future mechanistic interrogations of obesity and metabolic disease in pregnancy and vertical transmission of pathogenic traits.

Deletion of hepatic small heterodimer partner ameliorates development of nonalcoholic steatohepatitis in mice

Small heterodimer partner (SHP, Nr0b2) is an orphan nuclear receptor that regulates bile acid, lipid, and glucose metabolism. Shp-/- mice are resistant to diet-induced obesity and hepatic steatosis. In this study, we explored the potential role of SHP in the development of nonalcoholic steatohepatitis (NASH). A 6-month Western diet (WD) regimen was used to induce NASH. Shp deletion protected mice from NASH progression by inhibiting inflammatory and fibrotic genes, oxidative stress, and macrophage infiltration. WD feeding disrupted the ultrastructure of hepatic mitochondria in WT mice but not in Shp-/- mice. In ApoE-/- mice, Shp deletion also effectively ameliorated hepatic inflammation after a 1 week WD regimen without an apparent antisteatotic effect. Moreover, Shp-/- mice resisted fibrogenesis induced by a methionine- and choline-deficient diet. Notably, the observed protection against NASH was recapitulated in liver-specific Shp-/- mice fed either the WD or methionine- and choline-deficient diet. Hepatic cholesterol was consistently reduced in the studied mouse models with Shp deletion. Our data suggest that Shp deficiency ameliorates NASH development likely by modulating hepatic cholesterol metabolism and inflammation.

Administration of Akebia Saponin D Improved Blood Lipid Levels and Pregnancy Outcomes in Mice with Gestational Diabetes Mellitus

Background

Gestational diabetes mellitus (GDM) is a prevalent and severe metabolic disease in pregnant women that is characterized by a high incidence. Placental oxidative stress and inflammation are recognized as the primary contributors to GDM pathogenesis. The repressive effect of akebia saponin D (ASD) on oxidative stress and inflammation has been demonstrated in various diseases.

Aims

To investigate the impact of ASD on GDM.

Study Design

Animal experimental study.

Methods

GDM mice were intraperitoneally treated with ASD. The effect of ASD on GDM symptoms, blood lipid levels, pancreatic tissue damage, gestational outcomes, oxidative stress, and inflammation was assessed via intraperitoneal glucose and insulin tolerance tests, serum glucose and insulin level determination, lipid biochemistry analysis, pathological staining, oxidative stress evaluation, western blot analysis, and enzyme-linked immunosorbent assay.

Results

ASD reduced the GDM-induced increase in body weight and blood glucose levels while restoring the decreased insulin levels associated with GDM. In addition, ASD improved the serum lipid parameters, pancreatic tissue damage, and gestational outcomes in GDM mice. Furthermore, ASD reversed the decreased levels of superoxide dismutase and glutathione while reducing the elevated concentrations of malondialdehyde and myeloperoxidase in GDM mice. In addition, ASD rescued the relative protein expression of nuclear factor-E2-related factor 2 and heme oxygenase-1 in the placenta of GDM mice. Additionally, ASD counteracted the increase in tumor necrosis factor-α, interleukin (IL)-6, and IL-1β levels in the sera and placenta of GDM mice.

Conclusion

ASD suppressed oxidative stress and inflammation to effectively relieve symptoms and gestational outcomes of the GDM mice.

NKG2D-mediated detection of metabolically stressed hepatocytes by innate-like T cells is essential for initiation of NASH and fibrosis

Metabolic-associated fatty liver disease (MAFLD) is a spectrum of clinical manifestations ranging from benign steatosis to cirrhosis. A key event in the pathophysiology of MAFLD is the development of nonalcoholic steatohepatitis (NASH), which can potentially lead to fibrosis and hepatocellular carcinoma, but the triggers of MAFLD-associated inflammation are not well understood. We have observed that lipid accumulation in hepatocytes induces expression of ligands specific to the activating immune receptor NKG2D. Tissue-resident innate-like T cells, most notably γδ T cells, are activated through NKG2D and secrete IL-17A. IL-17A licenses hepatocytes to produce chemokines that recruit proinflammatory cells into the liver, which causes NASH and fibrosis. NKG2D-deficient mice did not develop fibrosis in dietary models of NASH and had a decreased incidence of hepatic tumors. The frequency of IL-17A+ γδ T cells in the blood of patients with MAFLD correlated directly with liver pathology. Our findings identify a key molecular mechanism through which stressed hepatocytes trigger inflammation in the context of MAFLD.

Transcriptional regulation of adipogenin expression in liver steatosis by hepatic peroxisome proliferator-activated receptor gamma

The nuclear receptors peroxisome proliferator-activated receptor gamma (PPARγ) and adipogenin (ADIG) play vital roles in lipid metabolism. However, the interaction between PPARγ and ADIG during liver steatosis remains unclear. In this study, we aimed to investigate the role of PPARγ in the transcriptional regulation of hepatic ADIG expression. Adig was found to be highly expressed in various fatty liver mouse models. Although hepatic Adig was expressed at high levels in the fatty liver of type 2 diabetic ob/ob mice and was upregulated by PPARγ agonist treatment, it was expressed at significantly low levels in liver-specific Pparg-knockout mice. Moreover, hepatic Adig expression was observed in other mouse models of liver steatosis, such as the leptin receptor mutant db/db and alcohol-fed mice. Adig was also highly expressed in the white and brown adipose tissues, skeletal muscles, and heart of ob/ob mice. Reporter and electromobility shift assays showed that PPARγ positively regulates Adig transcriptional activity by directly binding to a functional PPARγ-responsive element in the promoter region. Our results indicate that Adig is a novel target gene of hepatic PPARγ in liver steatosis.

Accelerated export of Dicer1 from lipid-challenged hepatocytes buffers cellular miRNA-122 levels and prevents cell death

Hepatocytes on exposure to high levels of lipids reorganize the metabolic program while fighting against the toxicity associated with elevated cellular lipids. The mechanism of this metabolic reorientation and stress management in lipid-challenged hepatocytes has not been well explored. We have noted the lowering of miR-122, a liver-specific miRNA, in the liver of mice fed with either a high-fat diet or a methionine-choline-deficient diet that is associated with increased fat accumulation in mice liver. Interestingly, low miR-122 levels are attributed to the enhanced extracellular export of miRNA processor enzyme Dicer1 from hepatocytes in the presence of high lipids. Export of Dicer1 can also account for the increased cellular levels of pre-miR-122-the substrate of Dicer1. Interestingly, restoration of Dicer1 levels in the mouse liver resulted in a strong inflammatory response and cell death in the presence of high lipids. Increasing death of hepatocytes was found to be caused by increased miR-122 levels in hepatocytes restored for Dicer1. Thus, the Dicer1 export by hepatocytes seems to be a key mechanism to combat lipotoxic stress by shunting out miR-122 from stressed hepatocytes. Finally, as part of this stress management, we determined that the Ago2-interacting pool of Dicer1, responsible for mature microribonucleoprotein formation in mammalian cells, gets depleted. miRNA-binder and exporter protein HuR is found to accelerate Ago2-Dicer1 uncoupling to ensure export of Dicer1 via extracellular vesicles in lipid-loaded hepatocytes.

Experimental Models for Studying Structural and Functional State of the Pathological Liver (Review)

Liver pathologies remain one of the leading causes of mortality worldwide. Despite a high prevalence of liver diseases, the possibilities of diagnosing, prognosing, and treating non-alcoholic and alcoholic liver diseases still have a number of limitations and require the development of new methods and approaches. In laboratory studies, various models are used to reconstitute the pathological conditions of the liver, including cell cultures, spheroids, organoids, microfluidic systems, tissue slices. We reviewed the most commonly used in vivo, in vitro, and ex vivo models for studying non-alcoholic fatty liver disease and alcoholic liver disease, toxic liver injury, and fibrosis, described their advantages, limitations, and prospects for use. Great emphasis was placed on the mechanisms of development of pathological conditions in each model, as well as the assessment of the possibility of reconstructing various key aspects of pathogenesis for all these pathologies. There is currently no consensus on the choice of the most adequate model for studying liver pathology. The choice of a certain effective research model is determined by the specific purpose and objectives of the experiment.

Establishment of Novel Mouse Model of Dietary NASH Rapidly Progressing into Liver Cirrhosis and Tumors

Non-alcoholic steatohepatitis (NASH), which is the most severe manifestation of non-alcoholic fatty liver disease (NAFLD), has been recognized as a major hepatocellular carcinoma (HCC) catalyst. However, the molecular mechanism of NASH-liver fibrosis-HCC sequence remains unclear and a specific and effective treatment for NASH has not yet been established. The progress in this field depends on the availability of reliable preclinical models which show the steady progression to NASH, liver cirrhosis, and HCC. However, most of the NASH mouse models that have been described to date develop NASH generally for more than 24 weeks and there is an uncertainty of HCC development. To overcome such shortcomings of experimental NASH studies, we established a novel NASH-HCC mouse model with very high reproducibility, generality, and convenience. We treated male C57BL/6J mice with a newly developed choline-deficient and methionine-restricted high-fat diet, named OYC-NASH2 diet, for 60 weeks. Treatment of OYC-NASH2 diet for 3 weeks revealed marked steatosis, lobular inflammation, and fibrosis, histologically diagnosed as NASH. Liver cirrhosis was observed in all mice with 48-week treatment. Liver nodules emerged at 12 weeks of the treatment, > 2 mm diameter liver tumors developed in all mice at 24 weeks of the treatment and HCC appeared after 36-week treatment. In conclusion, our rapidly progressive and highly reproducible NASH-liver cirrhosis-HCC model is helpful for preclinical development and research on the pathogenesis of human NAFLD-NASH-HCC. Our mouse model would be useful for the development of novel chemicals for NASH-HCC-targeted therapies.

NAFLD-Related HCC: Focus on the Latest Relevant Preclinical Models

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and one of the deadliest cancers worldwide. Despite extensive research, the biological mechanisms underlying HCC's development and progression remain only partially understood. Chronic overeating and/or sedentary-lifestyle-associated obesity, which promote Non-Alcoholic Fatty Liver Disease (NAFLD), have recently emerged as worrying risk factors for HCC. NAFLD is characterized by excessive hepatocellular lipid accumulation (steatosis) and affects one quarter of the world's population. Steatosis progresses in the more severe inflammatory form, Non-Alcoholic Steatohepatitis (NASH), potentially leading to HCC. The incidence of NASH is expected to increase by up to 56% over the next 10 years. Better diagnoses and the establishment of effective treatments for NAFLD and HCC will require improvements in our understanding of the fundamental mechanisms of the disease's development. This review describes the pathogenesis of NAFLD and the mechanisms underlying the transition from NAFL/NASH to HCC. We also discuss a selection of appropriate preclinical models of NAFLD for research, from cellular models such as liver-on-a-chip models to in vivo models, focusing particularly on mouse models of dietary NAFLD-HCC.

Beneficial Effects of a Curcumin Derivative and Transforming Growth Factor-β Receptor I Inhibitor Combination on Nonalcoholic Steatohepatitis

BACKGRUOUND

Curcumin 2005-8 (Cur5-8), a derivative of curcumin, improves fatty liver disease via AMP-activated protein kinase activation and autophagy regulation. EW-7197 (vactosertib) is a small molecule inhibitor of transforming growth factor β (TGF-β) receptor I and may scavenge reactive oxygen species and ameliorate fibrosis through the SMAD2/3 canonical pathway. This study aimed to determine whether co-administering these two drugs having different mechanisms is beneficial.

METHODS

Hepatocellular fibrosis was induced in mouse hepatocytes (alpha mouse liver 12 [AML12]) and human hepatic stellate cells (LX-2) using TGF-β (2 ng/mL). The cells were then treated with Cur5-8 (1 μM), EW-7197 (0.5 μM), or both. In animal experiments were also conducted during which, methionine-choline deficient diet, Cur5-8 (100 mg/kg), and EW-7197 (20 mg/kg) were administered orally to 8-week-old C57BL/6J mice for 6 weeks.

RESULTS

TGF-β-induced cell morphological changes were improved by EW-7197, and lipid accumulation was restored on the administration of EW-7197 in combination with Cur5-8. In a nonalcoholic steatohepatitis (NASH)-induced mouse model, 6 weeks of EW-7197 and Cur5-8 co-administration alleviated liver fibrosis and improved the nonalcoholic fatty liver disease (NAFLD) activity score.

CONCLUSION

Co-administering Cur5-8 and EW-7197 to NASH-induced mice and fibrotic hepatocytes reduced liver fibrosis and steatohepatitis while maintaining the advantages of both drugs. This is the first study to show the effect of the drug combination against NASH and NAFLD. Similar effects in other animal models will confirm its potential as a new therapeutic agent.

The Development of Nonalcoholic Fatty Liver Disease and Metabolic Syndromes in Diet-Induced Rodent Models

Dietary macronutrients are essential for metabolic regulation and insulin function. The present study examined the effects of different high-fat diets (HFDs) and high-carbohydrate diets (HCDs) on the development of non-alcoholic fatty liver disease and metabolic syndrome indices in healthy adult male Wistar albino rats. Forty-two rats were distributed into six groups (n = 7), which were fed the following for 22 weeks: (1) a control diet; (2) a high-carbohydrate, low-fat diet (HCD-LFD); (3) high-saturated-fat, low-carbohydrate diet (HSF-LCD); (4) a high-monounsaturated-fat diet (HMUSF); (5) a high medium-chain fat diet (HMCF); and a (6) a high-carbohydrate, high-fiber diet (HCHF). In comparison to the control, the body weight increased in all the groups. The HSF-LCD group showed the highest levels of cholesterol, triglyceride, low-density lipoprotein, hepatic enzyme, insulin resistance, and Homeostatic Model Assessment for Insulin Resistance. A liver histology analysis of the HSF-LCD group showed macrovesicular hepatic steatosis associated with large hepatic vacuolation. Additionally, it showed marked periportal fibrosis, especially around the blood vessels and blood capillaries. The lowest levels of fasting glycemia, insulin, and HOMA-IR were observed in the HCHF group. In conclusion, these findings show that dietary saturated fat and cholesterol are principal components in the development and progression of non-alcoholic fatty liver disease in rats, while fiber showed the greatest improvement in glycemic control.

In Vivo and In Vitro Models to Study Liver Fibrosis: Mechanisms and Limitations

Liver fibrosis is a common result of liver injury owing to various kinds of chronic liver diseases. A deeper understanding of the pathophysiology of liver fibrosis and identifying potential therapeutic targets of liver fibrosis is important because liver fibrosis may progress to advanced liver diseases, such as cirrhosis and hepatocellular carcinoma. Despite numerous studies, the underlying mechanisms of liver fibrosis remain unclear. Mechanisms of the development and progression of liver fibrosis differ according to etiologies. Therefore, appropriate liver fibrosis models should be selected according to the purpose of the study and the type of underlying disease. Many in vivo animal and in vitro models have been developed to study liver fibrosis. However, there are no perfect preclinical models for liver fibrosis. In this review, we summarize the current in vivo and in vitro models for studying liver fibrosis and highlight emerging in vitro models, including organoids and liver-on-a-chip models. In addition, we discuss the mechanisms and limitations of each model.

Comparison of pharmacokinetic profiles of seven major bioactive components in normal and non-alcoholic fatty liver disease (NAFLD) rats after oral administration of Ling-Gui-Zhu-Gan decoction by UPLC-MS/MS

A sensitive and rapid ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was hereby developed for the determination of seven components, namely, glycyrrhizic acid, glycyrrhetinic acid, dehydrotumulosic acid, isoliquiritin, liquiritin, atractylenolide III, and cinnamic acid, in the plasma of rats after the oral administration of Ling-Gui-Zhu-Gan decoction (LGZGD). Besides, this very method was methodologically validated for specificity, linearity, inter-day and intra-day precision, accuracy, matrix effect, extraction recovery, and stability. It was also successfully used for the first time to compare the pharmacokinetic characteristics of the seven components after oral administration of LGZGD to normal rats and non-alcoholic fatty liver disease (NAFLD) rats. The results indicated significant differences between the pharmacokinetic characteristics of normal and NAFLD rats. To further reveal the different pharmacokinetic behaviors, the expressions of enzymes and transporters in the liver of normal and NAFLD rats were detected using UPLC-MS/MS. In the NAFLD rats, UDP-glucuronosyltransferase 1-1 (UGT1A1) and nine transporters were significantly inhibited and a positive correlation was observed between them and the AUC of the major components. The present results indicate that the pharmacokinetic differences between the normal and NAFLD rats might be attributed to the significant lower expression levels of both the metabolic enzyme UGT1A1 and nine transporter proteins in the NAFLD rats than in the normal rats. Meanwhile, UGT1A1 and the nine transporter proteins might be used as potential biomarkers to assess the ameliorative effect of LGZGD on NAFLD, which could provide useful information to guide the clinical application of LGZGD.

Roles of the peroxisome proliferator-activated receptors (PPARs) in the pathogenesis of nonalcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disease phenotypes which start with simple steatosis and lipid accumulation in the hepatocytes - a typical histological lesions characteristic. It may progress to non-alcoholic steatohepatitis (NASH) that is characterized by hepatic inflammation and/or fibrosis and subsequent onset of NAFLD-related cirrhosis and hepatocellular carcinoma (HCC). Due to the central role of the liver in metabolism, NAFLD is regarded as a result of and contribution to the metabolic abnormalities seen in the metabolic syndrome. Peroxisome proliferator-activated receptors (PPARs) has three subtypes, which govern the expression of genes responsible for energy metabolism, cellular development, inflammation, and differentiation. The agonists of PPARα, such as fenofibrate and clofibrate, have been used as lipid-lowering drugs in clinical practice. Thiazolidinediones (TZDs) - ligands of PPARγ, such as rosiglitazone and pioglitazone, are also used in the treatment of type 2 diabetes (T2D) with insulin resistance (IR). Increasing evidence suggests that PPARβ/δ agonists have potential therapeutic effects in improving insulin sensitivity and lipid metabolism disorders. In addition, PPARs ligands have been considered as potential therapeutic drugs for hypertension, atherosclerosis (AS) or diabetic nephropathy. Their crucial biological roles dictate the significance of PPARs-targeting in medical research and drug discovery. Here, it reviews the biological activities, ligand selectivity and biological functions of the PPARs family, and discusses the relationship between PPARs and the pathogenesis of NAFLD and metabolic syndrome. This will open new possibilities for PPARs application in medicine, and provide a new idea for the treatment of fatty liver and related diseases.

Rapid and Reliable Steatosis Rat Model Shrsp5-Dmcr for Cold Storage Experiment

Interventions for liver grafts with moderate macrovesicular steatosis have been important in enlarging donor pools. Here, we tested a high-fat and cholesterol (HFC) diet to create a steatosis model for cold hepatic preservation and reperfusion experiments. The aim of the present study was to assess the steatosis model's reliability and to show the resulting graft's quality for cold preservation and reperfusion experiment. Male SHRSP5-Dmcr rats were raised with an HFC diet for up to 2 weeks. The fat content was evaluated using magnetic resonance imaging (MRI) proton density fat fraction (PDFF). The nonalcoholic fatty liver disease activity score (NAS) was evaluated after excision. Steatosis created by 2 weeks of HFC diet was subjected to 24-hour cold storage in the University of Wisconsin and the original test solution (new sol.). Grafts were applied to isolated perfused rat livers for simulating reperfusion. The NAS were 2.2 (HFC 5 days), 3.3 (HFC 1 week), and 5.0 (HFC 2 weeks). Ballooning and fibrosis were not observed in any group. An MRI-PDFF showed 0.2 (HFC 0 days), 12.0 (HFC 1 week), and 18.9 (HFC 2 weeks). The NAS and MRI-PDFF values correlated. Many indices in the isolated perfused rat liver experiment tended to improve in the new sol. group but were insufficient. Although the new sol. failed to be effective, it acted at multiple sites under difficult conditions. In conclusion, the HFC diet for 2 weeks in SHRSP5-Dmcr rats, together with MRI-PDFF evaluation, is a reliable method for creating simple steatosis and provides good-quality cold preservation and reperfusion experiments.

Oxysterol-binding protein-like 3 is a novel target gene of peroxisome proliferator-activated receptor γ in fatty liver disease

Oxysterol-binding protein-like 3 (OSBPL3) plays a key role in the development of fatty liver disease. Herein, we found that OSBPL3 is highly expressed in the fatty liver of humans and mice. Although high expression of Osbpl3 was observed in the fatty liver of type 2 diabetic ob/ob mice, liver-specific Pparg knockout ameliorated this increase in these mice. Moreover, high hepatic Osbpl3 expression was observed in other mice models of fatty liver disease, such as leptin receptor-mutant db/db and alcohol-fed mice. Analysis of the human liver transcriptome data revealed that hepatic OSBPL3 expression is higher in patients with advanced non-alcoholic fatty liver disease (NAFLD) when compared to those with mild NAFLD. Reporter and electrophoretic mobility shift assays showed that PPARγ positively regulates Osbpl3 transcription by binding to the two functional PPARγ-responsive elements present in the 5' upstream region. Overall, our results indicate that Osbpl3 is a novel PPARγ target in the fatty liver.

The Effect of the Saffron Intervention on NAFLD Status and Related Gene Expression in a Rat Model

Background

According to the worldwide increasing prevalence of non-alcoholic fatty liver disease (NAFLD), the present study aimed to investigate the mechanism effects of saffron consumption on preventing NAFLD in a rat model.

Methods

In an experimental study, 12 rats were randomly divided into 2 groups to be evaluated in the prevention phase for 7 weeks. In the prevention phase, the animals were randomly assigned to either fed HFHS + 250 mg/kg saffron (S) or fed with HFHS. Afterward, parts of the liver were excised for histopathologic examination. Plasma concentrations of ALT, AST, GGT, ALP, serum lipids, insulin concentrations, plasma glucose, hs-CRP, and TAC were measured. Moreover, Also, the gene expression of 6 target genes was evaluated, including FAS, ACC1, CPT1 ،PPARα ،DGAT2, and SREBP 1-c at the beginning and end of the study. Also, the differences among groups were evaluated by the Mann-Whitney test for non-normal data and the independent t test for normal data.

Results

The prevention phase groups have a significant elevation in body weight ( P = 0.034) and food intake (P = 0.001) of the HFHS group versus HFHS + 250 mg/kg S group. Also, there was a significant difference between groups 1 and 2 for ALT (P = 0.011) and AST (P = 0.010), and TG (P = 0.040). The HFHS group had higher plasma levels of FBS (P = 0.001), insulin (P = 0.035), HOMA-IR (P = 0.032), and lower TAC (P = 0.041) versus the HFHS+ S group. Also, the difference between HFHS + 250 mg/kg S and HFHS for PPARα gene expression was significant (P = 0.030).

Conclusion

The present study showed that consumption of saffron could prevent developing NAFLD in rats at least partially through modulation in gene expression of PPARα.

Comparison of hepatic responses to glucose perturbation between healthy and obese mice based on the edge type of network structures

Interactions between various molecular species in biological phenomena give rise to numerous networks. The investigation of these networks, including their statistical and biochemical interactions, supports a deeper understanding of biological phenomena. The clustering of nodes associated with molecular species and enrichment analysis is frequently applied to examine the biological significance of such network structures. However, these methods focus on delineating the function of a node. As such, in-depth investigations of the edges, which are the connections between the nodes, are rarely explored. In the current study, we aimed to investigate the functions of the edges rather than the nodes. To accomplish this, for each network, we categorized the edges and defined the edge type based on their biological annotations. Subsequently, we used the edge type to compare the network structures of the metabolome and transcriptome in the livers of healthy (wild-type) and obese (ob/ob) mice following oral glucose administration (OGTT). The findings demonstrate that the edge type can facilitate the characterization of the state of a network structure, thereby reducing the information available through datasets containing the OGTT response in the metabolome and transcriptome.

Innate-like T lymphocytes in chronic liver disease

In addition to its metabolic activities, it is now clear that the liver hosts a number of diverse immune cell types that control tissue homeostasis. Foremost among these are innate-like T lymphocytes, including natural killer T (NKT) and mucosal-associated innate T (MAIT) cells, which are a population of specialized T cells with innate characteristics that express semi-invariant T cell receptors with non-peptide antigen specificity. As primary liver residents, innate-like T cells have been associated with immune tolerance in the liver, but also with a number of hepatic diseases. Here, we focus on the biology of NKT and MAIT cells and how they operate during the course of chronic inflammatory diseases that eventually lead to hepatocellular carcinoma.

Thymoquinone attenuates hepatic lipid accumulation by inducing autophagy via AMPK/mTOR/ULK1-dependent pathway in nonalcoholic fatty liver disease

Thymoquinone (TQ) has been proved to exert wide-ranging pharmacological activities, with anti-inflammatory, antioxidant, anticonvulsant, antimicrobial, anti-tumor, and antidiabetic properties. In this study, we investigated the beneficial effects of TQ on a high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) in C57BL/6 N mice in vivo and free fatty acid (FFA)-induced human hepatocellular carcinoma HepG2 cells in vitro. Further, the underlying mechanisms of TQ to promote hepatic autophagy were also discovered. Data showed that TQ caused (p < 0.01) body weight reduction, improved glucose homeostasis, alleviated hepatosteatosis, and decreased hepatic lipid accumulation related to the induction of autophagy in HFD-fed mice. In vitro, TQ obviously increased (p < 0.01) autophagic flux in FFA-induced HepG2 cells and consequently reduced the lipid accumulation in combination with activation of AMPK/mTOR/ULK1 signaling pathways. Moreover, pharmacological inhibition of the AMPK pathway by addition with AMPK inhibitor Compound C (CC) or silence of ULK1 by transfection with siRNA(ULK1) into HepG2 cells reversed these beneficial effects of TQ on triggering hepatic autophagy and reducing lipid accumulation (p < 0.01). Taken together, these results suggested that TQ alleviated hepatic lipid accumulation by triggering autophagy through the AMPK/mTOR/ULK1-dependent signaling pathway. Our study supports a potential role for TQ in ameliorating NAFLD.

Extraction, characterization, and anti-nonalcoholic steatohepatitis activity of a (1,3) (1,6)-β-D-glucan from the Polyporus umbellatus (Pers.) Fries

Nonalcoholic steatohepatitis (NASH) is a chronic liver disease characterized by inflammation and hepatic steatosis that may coincide with fibrotic activity. To date, no pharmacological agents have been approved for NASH treatment. Here, a homogeneous (1,3),(1,6)-β-D-glucan (PUP-W-1, Mw: 41.07 kDa) was successfully purified from Polyporus umbellatus (Pers.) Fries sclerotia and characterized. The analysis showed that the PUP-W-1 backbone consisted of a repeating chain of eight →3)-β-D-Glcp-(1 → units, with branched chains of four β-D-Glcp residues, joined by repeating 1,6-linkage units at the O-6 position of the backbone. The pharmacological effects of PUP-W-1 treatment in the context of NASH pathogenesis were explored using a methionine choline-deficient (MCD) diet-induced murine steatohepatitis model. The MCD model mice exhibited pronounced steatohepatitis, inflammatory activity, steatosis, stellate cell activation, and mild fibrotic activity. Treatment of the mice for three weeks with PUP-W-1 prevented the development of NASH due to the suppression of inflammation, lipid accumulation, and fibrosis. As suggested by these findings, PUP-W-1 may hold promise as a natural drug candidate or precursor for the treatment of NASH.

Bioactive Compounds from Brown Algae Alleviate Nonalcoholic Fatty Liver Disease: An Extensive Review

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases. The increasing NAFLD incidences are associated with unhealthy lifestyles. Currently, there are no effective therapeutic options for NAFLD. Thus, there is a need to develop safe, efficient, and economic treatment options for NAFLD. Brown algae, which are edible, contain abundant bioactive compounds, including polysaccharides and phlorotannins. They have been shown to ameliorate insulin resistance, as well as hepatic steatosis, and all of these biological functions can potentially alleviate NAFLD. Accumulating reports have shown that increasing dietary consumption of brown algae reduces the risk for NAFLD development. In this review, we summarized the animal experiments and clinical proof of brown algae and their bioactive compounds for NAFLD treatment within the past decade. Our findings show possible avenues for further research into the pathophysiology of NAFLD and brown algae therapy.

Nutritional Genomics in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a common chronic condition associated with genetic and environmental factors in which fat abnormally accumulates in the liver. NAFLD is epidemiologically associated with obesity, type 2 diabetes, and dyslipidemia. Environmental factors, such as physical inactivity and an unbalanced diet, interact with genetic factors, such as epigenetic mechanisms and polymorphisms for the genesis and development of the condition. Different genetic polymorphisms seem to be involved in this context, including variants in PNPLA3, TM6SF2, PEMT, and CHDH genes, playing a role in the disease's susceptibility, development, and severity. From carbohydrate intake and weight loss to omega-3 supplementation and caloric restriction, different dietary and nutritional factors appear to be involved in controlling the onset and progression of NAFLD conditions influencing metabolism, gene, and protein expression. The polygenic risk score represents a sum of trait-associated alleles carried by an individual and seems to be associated with NAFLD outcomes depending on the dietary context. Understanding the exact extent to which lifestyle interventions and genetic predispositions can play a role in the prevention and management of NAFLD can be crucial for the establishment of a personalized and integrative approach to patients.