Novel non-alcoholic steatohepatitis model with histopathological and insulin-resistant features

Sexual dimorphism of metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver condition. MASLD is a sexually dimorphic condition, with its development and progression influenced by sex chromosomes and hormones. Estrogens typically protect against, whereas androgens promote, MASLD. Therapeutic approaches for a sex-specific personalized medicine include estrogen replacement, androgen blockers, and novel drugs targeting hormonal pathways. However, the interactions between hormonal factors and inherited genetic variation impacts MASLD risk, necessitating more tailored therapies. Understanding sex disparities and the role of estrogens could improve MASLD interventions and management, whereas clinical trials addressing sex differences are crucial for advancing personalized treatment. This review explores the underappreciated impact of sexual dimorphism in MASLD and discusses the potential therapeutic application of sex-related hormones.

LY6D is crucial for lipid accumulation and inflammation in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a serious metabolic disorder characterized by excess fat accumulation in the liver. Over the past decade, NAFLD prevalence and incidence have risen globally. There are currently no effective licensed drugs for its treatment. Thus, further study is required to identify new targets for NAFLD prevention and treatment. In this study, we fed C57BL6/J mice one of three diets, a standard chow diet, high-sucrose diet, or high-fat diet, and then characterized them. The mice fed a high-sucrose diet had more severely compacted macrovesicular and microvesicular lipid droplets than those in the other groups. Mouse liver transcriptome analysis identified lymphocyte antigen 6 family member D (Ly6d) as a key regulator of hepatic steatosis and the inflammatory response. Data from the Genotype-Tissue Expression project database showed that individuals with high liver Ly6d expression had more severe NAFLD histology than those with low liver Ly6d expression. In AML12 mouse hepatocytes, Ly6d overexpression increased lipid accumulation, while Ly6d knockdown decreased lipid accumulation. Inhibition of Ly6d ameliorated hepatic steatosis in a diet-induced NAFLD mouse model. Western blot analysis showed that Ly6d phosphorylated and activated ATP citrate lyase, which is a key enzyme in de novo lipogenesis. In addition, RNA- and ATAC-sequencing analyses revealed that Ly6d drives NAFLD progression by causing genetic and epigenetic changes. In conclusion, Ly6d is responsible for the regulation of lipid metabolism, and inhibiting Ly6d can prevent diet-induced steatosis in the liver. These findings highlight Ly6d as a novel therapeutic target for NAFLD.

Enzymatically-epoxidized docosahexaenoic acid, 19,20-EpDPE, suppresses hepatic crown-like structure formation and nonalcoholic steatohepatitis fibrosis through GPR120

A hepatic crown-like structure (hCLS) formed by macrophages accumulating around lipid droplets and dead cells in the liver is a unique feature of nonalcoholic steatohepatitis (NASH) that triggers progression of liver fibrosis. As hCLS plays a key role in the progression of NASH fibrosis, hCLS formation has emerged as a potential therapeutic target. n-3 polyunsaturated fatty acids (n-3 PUFAs) have potential suppressive effects on NASH fibrosis; however, the mechanisms underlying this effect are poorly understood. Here, we report that n-3 PUFA-enriched Fat-1 transgenic mice are resistant to hCLS formation and liver fibrosis in a NASH model induced by a combination of high-fat diet, CCl4 and a Liver X receptor (LXR) agonist. Liquid chromatography-tandem mass spectrometry-based mediator lipidomics revealed that the amount of endogenous n-3 PUFA-derived metabolites, such as 17,18-dihydroxyeicosatetraenoic acid (17,18-diHETE), and 19,20-epoxy docosapentaenoic acid (19,20-EpDPE), was significantly elevated in Fat-1 mice, along with hCLS formation. In particular, DHA-derived 19,20-EpDPE produced by Cyp4f18 attenuated the hCLS formation and liver fibrosis in a G protein-coupled receptor 120 (GPR120)-dependent manner. These results indicated that 19,20-EpDPE is an endogenous active metabolite that mediates the preventive effect of n-3 PUFAs against NASH fibrosis.

Role of B Cell-Activating Factor in Fibrosis Progression in a Murine Model of Non-Alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease all over the world. Therapeutic strategies targeting its multidirectional pathways are required. Particularly, fibrosis is closely associated with its prognosis. We previously found that B cell-activating factor (BAFF) is associated with severity of NAFLD. Here, we determined the direct in vivo role of BAFF in the development of liver fibrosis. Histological and biochemical analyses were performed using wild-type and BAFF-deficient mice. We established a murine model of non-alcoholic steatohepatitis (NASH) using carbon tetrachloride injection accompanied by high-fat/high-cholesterol diet feeding. Additionally, in vitro analysis using mouse macrophage-like cell line RAW264.7 and primary hepatic stellate cells was performed. Hepatic steatosis and inflammation, and most importantly, the progression of liver fibrosis, were ameliorated in BAFF-deficient mice compared to those wild-type mice in our model. Additionally, BAFF deficiency reduced the number of CD11c⁺ M1-type macrophages in the liver. Moreover, BAFF stimulated RAW264.7 cells to secrete nitric oxide and tumor necrosis factor α, which drove the activation of hepatic stellate cells. This indicates that BAFF plays a crucial role in NASH development and may be a promising therapeutic target for NASH.

Genetic and Diet-Induced Animal Models for Non-Alcoholic Fatty Liver Disease (NAFLD) Research

A rapidly increasing incidence of non-alcoholic fatty liver disease (NAFLD) is noted worldwide due to the adoption of western-type lifestyles and eating habits. This makes the understanding of the molecular mechanisms that drive the pathogenesis of this chronic disease and the development of newly approved treatments of utmost necessity. Animal models are indispensable tools for achieving these ends. Although the ideal mouse model for human NAFLD does not exist yet, several models have arisen with the combination of dietary interventions, genetic manipulations and/or administration of chemical substances. Herein, we present the most common mouse models used in the research of NAFLD, either for the whole disease spectrum or for a particular disease stage (e.g., non-alcoholic steatohepatitis). We also discuss the advantages and disadvantages of each model, along with the challenges facing the researchers who aim to develop and use animal models for translational research in NAFLD. Based on these characteristics and the specific study aims/needs, researchers should select the most appropriate model with caution when translating results from animal to human.

The Promising Role of Chitosan-Poloxamer 188 Nanocrystals in Improving Diosmin Dissolution and Therapeutic Efficacy against Ferrous Sulfate-Induced Hepatic Injury in Rats

Diosmin (DSN) exhibits poor water solubility and low bioavailability. Although nanocrystals (NCs) are successful for improving drug solubility, they may undergo crystal growth. Therefore, DSN NCs were prepared, employing sonoprecipitation utilizing different stabilizers. The optimum stabilizer was combined with chitosan (CS) as an electrostatic stabilizer. NCs based on 0.15% w/v poloxamer 188 (PLX188) as a steric stabilizer and 0.04% w/v CS were selected because they showed the smallest diameter (368.93 ± 0.47 nm) and the highest ζ-potential (+40.43 ± 0.15 mV). Mannitol (1% w/v) hindered NC enlargement on lyophilization. FT-IR negated the chemical interaction of NC components. DSC and XRD were performed to verify the crystalline state. DSN dissolution enhancement was attributed to the nanometric rod-shaped NCs, the high surface area, and the improved wettability. CS insolubility and its diffusion layer may explain controlled DSN release from CS-PLX188 NCs. CS-PLX188 NCs were more stable than PLX188 NCs, suggesting the significance of the combined electrostatic and steric stabilization strategies. The superiority of CS-PLX188 NCs was indicated by the significantly regulated biomarkers, pathological alterations, and inducible nitric oxide synthase (iNOS) expression of the hepatic tissue compared to DSN suspension and PLX188 NCs. Permeation, mucoadhesion, and cellular uptake enhancement by CS may explain this superiority.

Modeling alcohol-associated liver disease in a human Liver-Chip

Alcohol-associated liver disease (ALD) is a global health issue and leads to progressive liver injury, comorbidities, and increased mortality. Human-relevant preclinical models of ALD are urgently needed. Here, we leverage a triculture human Liver-Chip with biomimetic hepatic sinusoids and bile canaliculi to model ALD employing human-relevant blood alcohol concentrations (BACs) and multimodal profiling of clinically relevant endpoints. Our Liver-Chip recapitulates established ALD markers in response to 48 h of exposure to ethanol, including lipid accumulation and oxidative stress, in a concentration-dependent manner and supports the study of secondary insults, such as high blood endotoxin levels. We show that remodeling of the bile canalicular network can provide an in vitro quantitative readout of alcoholic liver toxicity. In summary, we report the development of a human ALD Liver-Chip as a powerful platform for modeling alcohol-induced liver injury with the potential for direct translation to clinical research and evaluation of patient-specific responses.

Oxidative stress and Liver X Receptor agonist induce hepatocellular carcinoma in Non-alcoholic steatohepatitis model

BACKGROUND AND AIM

The incidence of non-alcoholic steatohepatitis (NASH)-related hepatocellular carcinoma (HCC) is progressively increasing. However, the pathophysiology and etiology of NASH progression to HCC are unknown. We hypothesized that steatosis was the key factor in NASH-related hepatocarcinogenesis and aimed to evaluate the effects of long-term liver X receptor (LXR) agonist stimulation on hepatic steatosis induced by a high-fat diet and oxidative stress.

METHODS

We used an LXR agonist (T0901317) and CCl4 to induce hepatic steatosis and oxidative stress, respectively. C57BL/6 mice fed with a high-fat diet were treated with either T0901317 + CCl4 (T09 + CCl4 group) or CCl4 alone (CCl4 group). T0901317 (2.5 mg/kg) and CCl4 (0.1 mL/kg) were intraperitoneally administered twice weekly for 24 weeks.

RESULTS

The liver-to-body weight ratio was significantly higher in the T09 + CCl4 group than in the CCl4 group. Mice in the T09 + CCl4 group exhibited abnormal lipid metabolism and NASH-like histopathological features. Additionally, all mice in the T09 + CCl4 group developed liver tumors diagnosed as well-differentiated HCC. The genes identified via microarray analysis were related to NASH and HCC development.

CONCLUSIONS

By combining long-term LXR agonist stimulation with oxidative stress and a high-fat diet, we successfully reproduced liver conditions in mice similar to those in humans with NASH and progression to HCC. Our results provide new insight into NASH-related HCC progression and therapy.

Liver Biopsy Hydroxyproline Content Is a Diagnostic for Hepatocellular Carcinoma in Murine Models of Nonalcoholic Steatohepatitis

There is increasing evidence that nonalcoholic steatohepatitis (NASH) is a risk factor for hepatocellular carcinoma (HCC) in the absence of cirrhosis, a phenomenon termed noncirrhotic HCC. Early diagnosis of HCC is critical to a favorable prognosis. We tested the hypothesis that hydroxyproline content of liver biopsy samples is diagnostic for HCC in murine models of NASH induced by diet or by diet and chemicals. The training set comprised mice fed a standard diet or a fast-food diet with or without administration of thioacetamide. At harvest, livers from the modified diet cohort exhibited NASH with a subset of NASH livers exhibiting HCC. Hydroxyproline content was measured in liver biopsy samples with tissue in the NASH+HCC cohort sampled from the remote, nontumor parenchyma. Plotting the receiver operating characteristics (ROC) with hydroxyproline as the continuous variable against the absence or presence of HCC yielded an area under ROC of 0.87, a threshold of >0.18 μg hydroxyproline/mg liver and sensitivity of 91% with a specificity of 83.3%. The use of liver hydroxyproline content as a diagnostic for HCC in a test set comprising healthy, NASH and NASH+HCC livers proved 87% accurate.

Protective effect of lyophilized sapodilla (Manilkara zapota) fruit extract against CCl4-induced liver damage in rats

The tropical fruit sapodilla (Manilkara zapota syn. Achras zapota) is a rich source of nutrients, minerals and a myriad of bioactive phytochemicals such as flavonoids and catechins. Pharmacologically, sapodilla has been shown to exhibit anti-bacterial, anti-parasitic, anti-fungal, antiglycative, hypocholesterolemic and anti-cancer effects. However, its influence on hepatic tissue and serum lipids remains obscure. To address this, we used an in vivo model of liver damage to elucidate the effect of lyophilized sapodilla extract (LSE) treatment in carbon tetra chloride (CCl₄) intoxicated rats. Exposure of CCl₄ resulted in elevation of serum biomarkers of liver damage (aspartate transaminase, alanine aminotransferase, γ-glutamyl transferase and alkaline phosphatase), bilirubin and dysregulation of serum lipid profile (cholesterol and triglycerides). These effects were significantly and dose-dependently reversed by LSE treatment (250 and 500 mg/kg). Administration of LSE also reduced the structural damage caused by CCl₄ in the liver. Furthermore, determination of oxidative stress parameters (malondialdehyde and non-protein sulfhydryls) revealed that LSE treatment mitigated CCl₄-triggered modulation of both molecules. LSE also showed a strong antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In conclusion, the present study discloses the hepatoprotective and lipid-lowering effects of lyophilized sapodilla extract against CCl₄-induced liver damage, an effect, at least in part, mediated by its antioxidant activity.

Glycerol-3-phosphate Acyltransferase1 Is a Model-Agnostic Node in Nonalcoholic Fatty Liver Disease: Implications for Drug Development and Precision Medicine

Left untreated nonalcoholic fatty liver disease (NAFLD) can progress to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The observed failure of clinical trials in NASH may suggest that current model systems do not fully recapitulate human disease, and/or hallmark pathological features of NASH may not be driven by the same pathway in every animal model let alone in each patient. Identification of a model-agnostic disease-associated node can spur the development of effective drugs for the treatment of liver disease. Glycerol-3-phosphate acyltransferase1 (GPAT1) plays a pivotal role in lipid accumulation by shunting fats away from oxidation. In the present study, hepatic GPAT1 expression was evaluated in three etiologically different models of NAFLD. Compared to the sham cohort, hepatic GPAT1 mRNA levels were elevated by ∼5-fold in steatosis and NASH with fibrosis with immunofluorescent staining revealing increased GPAT1 in the fatty liver. A significant and direct correlation (r = 0.88) was observed between hepatic GPAT1 mRNA expression and severity of the liver disease. Picrosirius red staining revealed a logarithmic relation between hepatic GPAT1 mRNA expression and scar. These data suggest that hepatic GPAT1 is an early disease-associated model-agnostic node in NAFLD and form the basis for the development of a potentially successful therapeutic against NASH.

Isorhamnetin Alleviates Steatosis and Fibrosis in Mice with Nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH) is the most severe and progressive form of nonalcoholic fatty liver disease (NAFLD), which can lead to life-threatening conditions, however, there is still no approved drug for the treatment of NASH. In this study we used human-like NASH mouse model and treated orally with isorhamnetin at a dose of 50 mg/kg to analyze the effect of isorhamnetin on the progression of NASH. NASH-induced mice represented severe steatosis with inflammation, and fibrosis in liver accompanied with high level of liver injury markers in serum. Isorhamnetin treatment reduced intrahepatic lipid accumulation and TG content by inhibiting de novo lipogenic pathway in NASH-induced mice. Consistent with this, isorhamnetin-treated NASH mice showed improved liver injury markers, reduced collagen deposition as well as decreased gene expression of fibrogenic markers. Taken together, here we showed for the first time that synthesized isorhamnetin alleviates pathologic features of NASH and thus can potentially contribute to NASH drug development.

Animal models of NAFLD from the pathologist's point of view

Fatty liver disease is a multifactorial world-wide health problem resulting from a complex interplay between liver, adipose tissue and intestine and initiated by alcohol abuse, overeating, various types of intoxication, adverse drug reactions and genetic or acquired metabolic defects. Depending on etiology fatty liver disease is commonly categorized as alcoholic or non-alcoholic. Both types may progress from simple steatosis to the necro-inflammatory lesion of alcoholic (ASH) and non-alcoholic steatohepatitis (NASH), respectively, and finally to cirrhosis and hepatocellular carcinoma. Animal models are helpful to clarify aspects of pathogenesis and progression. Generally, they are classified as nutritional (dietary), toxin-induced and genetic, respectively, or represent a combination of these factors. Numerous reviews are dealing with NASH animal models designed to imitate as closely as possible the metabolic situation associated with human disease. This review focuses on currently used mouse models of NASH with particular emphasis on liver morphology. Despite metabolic similarities most models (except those with chemically or genetically induced porphyria or keratin 18-deficiency) fail to develop the morphologic key features of NASH, namely hepatocyte ballooning and formation of histologically and immunohistochemically well-defined Mallory-Denk-Bodies (MDBs). Although MDBs are not universally detectable in ballooned hepatocytes in NASH their experimental reproduction and analysis may, however, significantly contribute to our understanding of important pathogenic aspects of NASH despite the obvious differences in etiology.

Evaluation of safety for hepatectomy in a novel mouse model with nonalcoholic-steatohepatitis

AIM

To investigate whether the liver resection volume in a newly developed nonalcoholic steatohepatitis (NASH) model influences surgical outcome.

METHODS

For establishment of a NASH model, mice were fed a high-fat diet for 4 wk, administered CCl₄ for the last 2 wk, and administered T0901317 for the last 5 d. We divided these mice into two groups: A 30% partial hepatectomy (PH) of NASH liver group and a 70% PH of NASH liver group. In addition, a 70% PH of normal liver group served as the control. Each group was evaluated for survival rate, regeneration, apoptosis, necrosis and DNA expression after PH.

RESULTS

In the 70% PH of NASH group, the survival rate was significantly decreased compared with that in the control and 30% PH of NASH groups (P < 0.01). 10 of 32 mice in the NASH 70% PH group died within 48 h after PH. Serum aspartate aminotransferase (AST) levels and total bilirubin (T-Bil) in the NASH 70% PH group were significantly higher than the levels in the other two groups (AST: P < 0.05, T-Bil: P < 0.01). In both PH of NASH groups, signaling proteins involved in regeneration were expressed at lower levels than those in the control group (P < 0.01). The 70% PH of NASH group also exhibited a lower number of Ki-67-positive cells and higher rates of apoptosis and necrosis than the NASH 30% PH group (P < 0.01). In addition, DNA microarray assays showed differences in gene expression associated with cell cycle arrest and apoptosis.

CONCLUSION

The function of the residual liver is impaired in fatty liver compared to normal liver. A larger residual volume is required to maintain liver functions in mice with NASH.