Modeling Diet-Induced NAFLD and NASH in Rats: A Comprehensive Review

Empagliflozin ameliorates liver fibrosis in NASH rat model via targeting hepatic NF-κB/SOX9/OPN signaling and osteocalcin level

Non-alcoholic steatohepatitis (NASH) may be associated with tissue fibrotic changes and can be treated via different therapeutic tools which may however either initiate weak or long-term side effects that minimize its use. Empagliflozin (EMPA) is an oral anti-diabetic drug which has characteristic effects during hepatic steatosis regarding lipid accumulation and insulin resistance. In this study, we aimed to investigate an additional mechanism through which EMPA can exert and potentiate its anti-inflammatory and anti-fibrotic effects in NASH rat model. Male Wistar albino rats fed on high fat diet (HFD) and 20% fructose in drinking water for 18 weeks and received EMPA (30 mg/kg/day, orally) starting from week 11. Body and liver weights, homeostatic model assessment of insulin resistance (HOMA-IR), lipid profile, liver function tests, other biochemical and histological parameters were determined. HFD joined with fructose intake significantly increased body and liver weights, HOMA-IR value, hepatic inflammatory and fibrotic markers, liver transaminases, hepatic expression of nuclear factor-kappa B (NF-κB), sex determining region Y box 9 (SOX 9), and osteopontin (OPN) with significant decrease in hepatic osteocalcin (OCN). Intense hepatic lesions with severe microsteatosis and deposition of collagen fibers were clearly observed. Effectively, EMPA restored the normal liver functions, downregulated hepatic inflammatory cytokines, NF-κB, SOX 9, OPN, and increased OCN level. These results highlight another pathway illustrated the anti-fibrotic effects of EMPA against liver fibrosis probably through downregulation of NF-κB/SOX 9/OPN signaling along with upregulation of hepatic OCN which may potentiate the valuable anti-inflammatory and anti-fibrotic effects of EMPA.

Voluntary exercise fails to prevent metabolic dysfunction-associated steatotic liver disease progression in male rats fed a high-fat high-cholesterol diet

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major public health issue with a worldwide prevalence of 30%-32%. In animal models, voluntary exercise may be an alternative to forced physical activity, avoiding stress, potential injuries, and being logistically simpler. Here, we assessed voluntary exercise (Vex) in Sprague-Dawley rats fed a high-fat, high-cholesterol diet for 18 weeks to induce MASLD. We quantified workload (speed and distance) using exercise wheels and evaluated energy expenditure using calorimetric cages. MASLD progression was assessed using circulating and hepatic biochemical and gene markers of steatosis, inflammation, and fibrosis. The animals ran an average of 301 km during the study period, with the average daily distance peaking at 4937 m/day during Weeks 3-4 before decreasing to 757 m/day by the end of the study. Rats exposed to Vex showed no improvement in any of the MASLD-associated features, such as steatosis, inflammation, or fibrosis. Rats exposed to Vex exhibited a higher total energy expenditure during the night phase (+0.35 kcal/h; p = 0.003) without resulting in any effect on body composition. We conclude that, in our experimental conditions, Vex failed to prevent MASLD progression in male Sprague-Dawley rats exposed to a high-fat high-cholesterol diet for 18 weeks.

Hepatic-Accumulated Obeticholic Acid and Atorvastatin Self-Assembled Nanocrystals Potentiate Ameliorative Effects in Treatment of Metabolic-Associated Fatty Liver Disease

Exploration of medicines for efficient and safe management of metabolic-associated fatty liver disease (MAFLD) remains a challenge. Obeticholic acid (OCA), a selective farnesoid X receptor agonist, has been reported to ameliorate injury and inflammation in various liver diseases. However, its clinical application is mainly limited by poor solubility, low bioavailability, and potential side effects. Herein a hepatic-targeted nanodrugs composed of OCA and cholesterol-lowering atorvastatin (AHT) with an ideal active pharmaceutical ingredient (API) content for orally combined treatment of MAFLD is created. Such carrier-free nanocrystals (OCAHTs) are self-assembled, not only improving the stability in gastroenteric environments but also achieving hepatic accumulation through the bile acid transporter-mediated enterohepatic recycling process. Orally administrated OCAHT outperforms the simple combination of OCA and AHT in ameliorating of liver damage and inflammation in both acetaminophen-challenged mice and high-fat diet-induced MAFLD mice with less systematic toxicity. Importantly, OCAHT exerts profoundly reverse effects on MAFLD-associated molecular pathways, including impairing lipid metabolism, reducing inflammation, and enhancing the antioxidation response. This work not only provides a facile bile acid transporter-based strategy for hepatic-targeting drug delivery but also presents an efficient and safe full-API nanocrystal with which to facilitate the practical translation of nanomedicines against MAFLD.

Hepatocyte ballooning and steatosis in early and late gestation without liver malfunction: Effects of low protein/high carbohydrate diet

Pregnancy is a challenging metabolic and physiological condition. The aim of this study was to include a second demanding situation as a low protein/high carbohydrate diet (LPHCD) to characterize the histological and functional responses of the maternal liver. It is unknown how the maternal liver responds during early and late pregnancy to LPHCD intake. We explored early pregnancy (3 and 8 gestational age, G) and late pregnancy (15 and 20 G). The results indicated that pregnant rats under control diet showed an evident presence of ballooned hepatocytes, lipid vesicles and edema at late pregnancy (15G); in contrast, pregnant rats under LPHCD showed similar pattern of histological modification but at early pregnancy (3G). Unexpectedly, the serum biomarkers didn't display functional alterations in either group, despite of the evident histological changes no liver malfunction was detected. We conclude that pregnant rats fed with control diet and experimental LPHCD, are subjected to metabolic and physiological conditions that impact the histopathological condition of the maternal liver. Control diet promoted the histological modifications during late pregnancy whereas LPCHCD advanced the onset of these changes. Further experiments are needed to explore the biochemical mechanisms that underlie these histological modifications. Our results are also an example of the resilience associated with the pregnancy: since no functional hepatic alterations accompanied the histopathological changes, another conclusion is that no evident pathological condition was detected in this nutritional protocol.

Novel Noninvasive Paraclinical Study Method for Investigation of Liver Diseases

Based on a prior university patent, the authors developed a novel type of bioimpedance-based test method to noninvasively detect nonalcoholic fatty liver disease (NAFLD). The development of a new potential NAFLD diagnostic procedure may help to understand the underlying mechanisms between NAFLD and severe liver diseases with a painless and easy-to-use paraclinical examination method, including the additional function to detect even the earlier stages of liver disease. The aim of this study is to present new results and the experiences gathered in relation to NAFLD progress during animal model and human clinical trials.

Utilization of Food-Derived β-Glucans to Prevent and Treat Non-Alcoholic Fatty Liver Disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease nowadays. Currently, there is no officially approved drug to treat NAFLD. In view of the increasing global prevalence of NAFLD and an absence of treatments, the development of effective treatments is of utmost importance. β-glucan, a natural bioactive polysaccharide, has demonstrated hepatoprotective effects in NAFLD prevention and treatment. This review solely focuses on gathering the published preclinical animal studies that demonstrated the anti-liver injury, anti-steatotic, anti-inflammatory, anti-fibrotic, and antioxidant activities of β-glucan. The impact of β-glucan on gut microbiota and its metabolites including short-chain fatty acids and bile acids as the underlying mechanism for its bioactive beneficial effect on NAFLD is also explored. Given the limited knowledge of β-glucan on anti-fibrotic activity, bile acid metabolism, and gut microbiota function, additional relevant research is highly encouraged to lay a solid foundation for the use of food-derived β-glucan as a functional food for NAFLD. It is envisaged that further investigation of food-derived β-glucan in human clinical studies should be carried out for its wider utilization.

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.

Raspberry ketone improves non-alcoholic fatty liver disease induced in rats by modulating sphingosine kinase/sphingosine-1-phosphate and toll-like receptor 4 pathways

OBJECTIVES

To investigate the therapeutic role of calorie-restricted diet (CR) and raspberry ketone (RK) in non-alcoholic fatty liver disease (NAFLD) and the implication of sphingosine kinase-1 (SphK1)/sphingosine-1-phosphate (S1P) and toll-like receptor 4 (TLR4) signalling.

METHODS

NAFLD was induced by feeding rats high-fat-fructose-diet (HFFD) for 6 weeks. Rats were then randomly assigned to three groups (n = 6 each); NAFLD group continued on HFFD for another 8 weeks. CR group was switched to CR diet (25% calorie restriction) for 8 weeks and RK group was switched to normal diet and received RK (55 mg/kg/day; orally) for 8 weeks. Another six rats were used as normal control.

KEY FINDINGS

HFFD induced a state of NAFLD indicated by increased fat deposition in liver tissue along with dyslipidemia, elevated liver enzymes, oxidative stress and inflammation. Either CR diet or RK reversed these changes and decreased HFFD-induced elevation of hepatic SphK1, S1P, S1PR1 and TLR4. Of notice, RK along with a normal calorie diet was even better than CR alone in most studied parameters.

CONCLUSIONS

SphK1/S1P and TLR4 are interconnected and related to the establishment of HFFD-induced NAFLD and can be modulated by RK. Supplementation of RK without calorie restriction to patients with NAFLD unable to follow CR diet to achieve their treatment goals would be a promising therapeutic modality.

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.

Acetaminophen-Induced Hepatotoxicity in Obesity and Nonalcoholic Fatty Liver Disease: A Critical Review

The epidemic of obesity, type 2 diabetes and nonalcoholic liver disease (NAFLD) favors drug consumption, which augments the risk of adverse events including liver injury. For more than 30 years, a series of experimental and clinical investigations reported or suggested that the common pain reliever acetaminophen (APAP) could be more hepatotoxic in obesity and related metabolic diseases, at least after an overdose. Nonetheless, several investigations did not reproduce these data. This discrepancy might come from the extent of obesity and steatosis, accumulation of specific lipid species, mitochondrial dysfunction and diabetes-related parameters such as ketonemia and hyperglycemia. Among these factors, some of them seem pivotal for the induction of cytochrome P450 2E1 (CYP2E1), which favors the conversion of APAP to the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). In contrast, other factors might explain why obesity and NAFLD are not always associated with more frequent or more severe APAP-induced acute hepatotoxicity, such as increased volume of distribution in the body, higher hepatic glucuronidation and reduced CYP3A4 activity. Accordingly, the occurrence and outcome of APAP-induced liver injury in an obese individual with NAFLD would depend on a delicate balance between metabolic factors that augment the generation of NAPQI and others that can mitigate hepatotoxicity.

An Egg White-Derived Peptide Enhances Systemic Insulin Sensitivity and Modulates Markers of Non-Alcoholic Fatty Liver Disease in Obese, Insulin Resistant Mice

Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome, is a global health problem. Currently, no pharmacological treatment is approved for NAFLD. Natural health products, including bioactive peptides, are potential candidates to aid in the management of metabolic syndrome-related conditions, including insulin resistance and obesity. In this study, we hypothesized that an egg-white-derived bioactive peptide QAMPFRVTEQE (Peptide 2) would improve systemic and local white adipose tissue insulin sensitivity, thereby preventing high-fat diet-induced exacerbation of pathological features associated with NAFLD, such as lipid droplet size and number, inflammation, and hepatocyte hypertrophy in high-fat diet-fed mice. Similar to rosiglitazone, Peptide 2 supplementation improved systemic insulin resistance during the hyperinsulinemic-euglycemic clamp and enhanced insulin signalling in white adipose tissue, modulating ex vivo lipolysis. In the liver, compared with high-fat diet fed animals, Peptide 2 supplemented animals presented decreased hepatic cholesterol accumulation (p < 0.05) and area of individual hepatic lipid droplet by around 50% (p = 0.09) and reduced hepatic inflammatory infiltration (p < 0.05) whereas rosiglitazone exacerbated steatosis. In conclusion, Peptide 2 supplementation improved insulin sensitivity and decreased hepatic steatosis, unlike the insulin-sensitizing drug rosiglitazone.

Orthosiphon aristatus (Blume) Miq Alleviates Non-Alcoholic Fatty Liver Disease via Antioxidant Activities in C57BL/6 Obese Mice and Palmitic-Oleic Acid-Induced Steatosis in HepG2 Cells

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent form of liver disease. Orthosiphon aristatus (Blume) Miq, a traditional plant in South Asia, has previously been shown to attenuate obesity and hyperglycaemic conditions. Eight weeks of feeding C57BL/6 mice with the standardized O. aristatus extract (400 mg/kg) inhibited the progression of NAFLD. Liver enzymes including alanine aminotransferase and aspartate transaminase were significantly reduced in treated mice by 74.2% ± 7.69 and 52.8% ± 7.83, respectively. Furthermore, the treated mice showed a reduction in serum levels of glucose (50% ± 5.71), insulin (70.2% ± 12.09), total cholesterol (27.5% ± 15.93), triglycerides (63.2% ± 16.5), low-density lipoprotein (62.5% ± 4.93) and atherogenic risk index relative to the negative control. Histologically, O. aristatus reversed hepatic fat accumulation and reduced NAFLD severity. Notably, our results showed the antioxidant activity of O. aristatus via increased superoxide dismutase activity and a reduction of hepatic malondialdehyde levels. In addition, the levels of serum pro-inflammatory mediators (IL-6 and TNFα) decreased, indicating anti-inflammatory activity. The aqueous, hydroethanolic and ethanolic fractions of O. aristatus extract significantly reduced intracellular fat accumulation in HepG2 cells that were treated with palmitic-oleic acid. Together, these findings suggest that antioxidant activities are the primary mechanism of action of O. aristatus underlying the anti-NAFLD effects.

Characterization of hepatic inflammatory changes in a C57BL/6J mouse model of alpha1-antitrypsin deficiency

Alpha-1 antitrypsin deficiency (AATD) is a genetic disease caused by a hepatic accumulation of mutant alpha-1 antitrypsin (ZAAT). Individuals with AATD are prone to develop a chronic liver disease that remains undiagnosed until late stage of the disease. Here, we sought to characterize the liver pathophysiology of a human transgenic mouse model for AATD with a manifestation of liver disease compared with normal transgenic mice model. Male and female transgenic mice for normal (Pi*M) and mutant variant (Pi*Z) human alpha-1 antitrypsin at 3 and 6 mo of age were subjected to this study. The progression of hepatic ZAAT accumulation, hepatocyte injury, steatosis, liver inflammation, and fibrotic features were monitored by performing an in vivo study. We have also performed a Next-Gene transcriptomic analysis of the transgenic mice liver tissue 16 h after lipopolysaccharide (LPS) administration to delineate liver inflammatory response in Pi*Z mice as compared with Pi*M. Our results show hepatic ZAAT accumulation, followed by hepatocyte ballooning and liver steatosis developed at 3 mo in Pi*Z mice compared with the mice carrying normal variant of human alpha-1 antitrypsin. We observed higher levels of hepatic immune cell infiltrations in both 3- and 6-mo-old Pi*Z mice compared with Pi*M as an indication of liver inflammation. Liver fibrosis was observed as accumulation of collagen in 6-mo-old Pi*Z liver tissues compared with Pi*M control mice. Furthermore, the transcriptomic analysis revealed a dysregulated liver immune response to LPS in Pi*Z mice compared with Pi*M. Of particular interest for translational work, this study aims to establish a mouse model of AATD with a strong manifestation of liver disease that will be a valuable in vivo tool to study the pathophysiology of AATD-mediated liver disease. Our data suggest that the human transgenic mouse model of AATD could provide a suitable model for the evaluation of therapeutic approaches and preventive reagents against AATD-mediated liver disease.NEW & NOTEWORTHY We have characterized a mouse model of human alpha-1 antitrypsin deficiency with a strong manifestation of liver disease that can be used as an in vivo tool to test preventive and therapeutic reagents. Our data explores the altered immunophenotype of alpha-1 antitrypsin-deficient liver macrophages and suggests a relationship between acute inflammation, immune response, and fibrosis.

Black ginseng protects against Western diet-induced nonalcoholic steatohepatitis by modulating the TLR4/NF-κB signaling pathway in mice

Black ginseng (BG) shows beneficial effects on liver injury, but the related mechanism has not been fully revealed. This study attempted to investigate the protective effects and associated mechanisms of BG against nonalcoholic steatohepatitis (NASH). Twelve ginsenosides in BG were annotated by ultrahigh performance liquid chromatography combined with high resolution mass spectrometry (UHPLC-HRMS). The Western diet (WD) together with the low-dose CCl₄ was given to mice to create the NASH model. Histopathological examination and liver/serum biochemical analysis revealed that the NASH mice displayed severe steatosis and liver damage compared with control mice. After BG administration, the serum and liver triglycerides (TG) concentrations and the serum level of low-density lipoprotein (LDL) were dramatically reduced. Besides, the BG treatment greatly decreased the serum values of interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α), and the hepatic expression of fibrotic-related genes, such as alpha-smooth muscle actin (α-SMA) and collagen type I alpha 1 (Col1α1). We further discovered that BG administration could block the protein expression of toll-like receptor 4 (TLR4) and the phosphorylation of nuclear factor-kappa B p65 (NF-κB p65), indicating that BG exerted a liver protective effect via regulating the TLR4/NF-κB pathway. This study demonstrated the therapeutic efficacy and the associated mechanism of BG in the treatment of NASH, giving evidence for BG as a potential functional food to prevent NASH. PRACTICAL APPLICATIONS: BG is a type of processed ginseng product that has been used as diet supplementation and has shown favorable effects on liver injury. However, the pharmacological impact of BG on NASH has not been studied in depth. The present study showed that BG could effectively reduce WD-induced liver fibrosis and inflammation through the TLR4/NF-κB axis, which indicated that BG has the potential to be utilized as a functional herb to attenuate liver injury.

Utility of Human Relevant Preclinical Animal Models in Navigating NAFLD to MAFLD Paradigm

Fatty liver disease is an emerging contributor to disease burden worldwide. The past decades of work established the heterogeneous nature of non-alcoholic fatty liver disease (NAFLD) etiology and systemic contributions to the pathogenesis of the disease. This called for the proposal of a redefinition in 2020 to that of metabolic dysfunction-associated fatty liver disease (MAFLD) to better reflect the current understanding of the disease. To date, several clinical cohort studies comparing NAFLD and MAFLD hint at the relevancy of the new nomenclature in enriching for patients with more severe hepatic injury and extrahepatic comorbidities. However, the underlying systemic pathogenesis is still not fully understood. Preclinical animal models have been imperative in elucidating key biological mechanisms in various contexts, including intrahepatic disease progression, interorgan crosstalk and systemic dysregulation. Furthermore, they are integral in developing novel therapeutics against MAFLD. However, substantial contextual variabilities exist across different models due to the lack of standardization in several aspects. As such, it is crucial to understand the strengths and weaknesses of existing models to better align them to the human condition. In this review, we consolidate the implications arising from the change in nomenclature and summarize MAFLD pathogenesis. Subsequently, we provide an updated evaluation of existing MAFLD preclinical models in alignment with the new definitions and perspectives to improve their translational relevance.

Liquorice root extract and isoliquiritigenin attenuate high-fat diet-induced hepatic steatosis and damage in rats by regulating AMPK

Objective: This study compared the ability of Liquorice roots aqueous extract (LRE) and its ingredient, isoliquiritigenin (ISL), in alleviating high-fat diet (HFD)-induced hepatic steatosis and examined if this effect involves activation of AMPK.Materials and methods: Control or HFD-fed rats were treated with the vehicle, LRE (200 mg/kg), or ISL (30 mg/kg) for 8 weeks orally.Results: ISL and LRE reduced HFD-induced hyperglycaemia, improved liver structure, lowered serum and hepatic lipids, and attenuated hepatic oxidative stress and inflammation. In the control and HFD-fed rats, ISL and LRE significantly stimulated the muscular and hepatic mRNA and protein levels of AMPK, improved oral glucose tolerance, reduced hepatic mRNA levels of SREBP1/2, and upregulated hepatic levels of PPARα and Bcl2. These effects were comparable for ISL and LRE and were prevented by co-administration of compound C, an AMPK inhibitor.Discussion and conclusion: ISL and LRE provide an effective theory to alleviate hepatic steatosis through activating AMPK.

A Nutraceutical Formulation Containing Brown Algae Reduces Hepatic Lipid Accumulation by Modulating Lipid Metabolism and Inflammation in Experimental Models of NAFLD and NASH

Recently, some preclinical and clinical studies have demonstrated the ability of brown seaweeds in reducing the risk factors for metabolic syndrome. Here, we analyzed the beneficial effect of a nutraceutical formulation containing a phytocomplex extracted from seaweeds and chromium picolinate in animal models of liver steatosis of differing severities (rats with non-alcoholic fatty liver disease (NAFLD) and its complication, non-alcoholic steatohepatitis (NASH)). This treatment led to a significant drop in hepatic fat deposition in both models (p < 0.01 vs. untreated animals), accompanied by a reduction in plasma inflammatory cytokines, such as interleukin 6, tumor necrosis factor α, and C reactive protein, and myeloperoxidase expression in liver tissue. Furthermore, a modulation of the molecular pathways involved in lipid metabolism and storage was demonstrated, since we observed the significant reduction of the mRNA levels of fatty acid synthase, diacylglycerol acyltransferases, the sterol-binding protein SREBP-1, and the lipid transporter perilipin-2, in both treated NAFLD and NASH rats in comparison to untreated ones. In conclusion, this nutraceutical product was effective in reducing liver steatosis and showed further beneficial effects on hepatic inflammation and glycemic control, which were particularly evident in rats characterized by a more severe condition, thus representing a therapeutic option for the treatment of NAFLD and NASH patients.

Pathogenesis from Inflammation to Cancer in NASH-Derived HCC

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and one of the deadliest cancers worldwide. As opposed to the majority of patients with HCC, approximately 20–30% of cases of non-alcoholic steatohepatitis (NASH)-derived HCC develop malignant tumours in the absence of liver cirrhosis. NASH is characterized by metabolic dysregulation, chronic inflammation and cell death in the liver, which provide a favorable setting for the transformation of inflammation into cancer. This review aims to describe the pathogenesis and the underlying mechanism of the transition from inflammation to cancer in NASH.

Aloe vera ameliorates hyperlipidemia, enhances endogenous antioxidant activity and regulates liver function in high fat diet fed mice

BACKGROUND: Prolonged high fat diet consumption was reported to cause metabolic disorders including obesity, NAFLD and insulin resistance. NAFLD is one of the common causes of liver failure with lipid accumulation and inflammation as the major driving forces for its progression. OBJECTIVE: The study was aimed at evaluating the benefits of Aloe vera supplementation on lipid profiles, antioxidant properties, liver function as well as the histology of liver, heart and brain on high fat diet induced toxicity in BALB/c mice. METHODS: Eighteen mice were divided into three groups (n = 6). Group 1 received normal diet (Vital feed), group 2 received high fat diet (HFD) i.e. 70 g of normal diet plus 30 g of margarine, while group 3 received high fat diet plus Aloe vera (HFD+AV) i.e. 80 g of HFD plus 20 g of Aloe vera gel. The mice were fed for 10 weeks and euthanized thereafter. The liver function, lipid profiles, antioxidant properties as well as liver, brain and heart histology were evaluated. RESULTS: The levels of cholesterol, triglycerides and low density lipoprotein were significantly increased (P <  0.05) in the HFD treated mice compared to the control. Liver catalase and superoxide dismutase activities were significantly increased (P <  0.05) in HFD+AV treated mice compared to the control and HFD treated mice. The liver of HFD+AV treated mice showed normal architecture while those of HFD treated mice showed numerous hepatic vacuoles indicative of fat droplets. CONCLUSIONS: Aloe vera supplementation regulated liver function and prevents hyperlipidemia. The resultant effect increased antioxidant activities thereby preventing liver injury and brain damage.

The presence of interferon affects the progression of non-alcoholic fatty liver disease

Inflammation and metabolic dysfunction are hallmarks of the progression of non-alcoholic fatty liver disease (NAFLD), which is the fastest-growing liver disease worldwide. Emerging evidence indicates that innate immune mechanisms are essential drivers of fibrosis development in chronic inflammatory liver diseases, including NAFLD. In this study, 142 NAFLD patients were genotyped for three IFNL4 single-nucleotide variants in order to investigate the genetic relationship between IFNL4 and fibrosis in NAFLD patients. We observed an overrepresentation of the non-functional IFNL4 allele in patients with significant fibrosis (>F2). Next, we investigated the potential protective role of interferon (IFN) in relation to the development of liver fibrosis in an animal model of non-alcoholic steatohepatitis (NASH). In contradiction to our hypothesis, the results showed an increase in fibrosis in IFN treated animals. Our study clearly indicates that IFN is able to affect the development of liver fibrosis, although our clinical and experimental data are conflicting.

Hepatic fibrosis 2022: Unmet needs and a blueprint for the future

Steady progress over four decades toward understanding the pathogenesis and clinical consequences of hepatic fibrosis has led to the expectation of effective antifibrotic drugs, yet none has been approved. Thus, an assessment of the field is timely, to clarify priorities and accelerate progress. Here, we highlight the successes to date but, more importantly, identify gaps and unmet needs, both experimentally and clinically. These include the need to better define cell-cell interactions and etiology-specific elements of fibrogenesis and their link to disease-specific drivers of portal hypertension. Success in treating viral hepatitis has revealed the remarkable capacity of the liver to degrade scar in reversing fibrosis, yet we know little of the mechanisms underlying this response. Thus, there is an exigent need to clarify the cellular and molecular mechanisms of fibrosis regression in order for therapeutics to mimic the liver's endogenous capacity. Better refined and more predictive in vitro and animal models will hasten drug development. From a clinical perspective, current diagnostics are improving but not always biologically plausible or sufficiently accurate to supplant biopsy. More urgently, digital pathology methods that leverage machine learning and artificial intelligence must be validated in order to capture more prognostic information from liver biopsies and better quantify the response to therapies. For more refined treatment of NASH, orthogonal approaches that integrate genetic, clinical, and pathological data sets may yield treatments for specific subphenotypes of the disease. Collectively, these and other advances will strengthen and streamline clinical trials and better link histologic responses to clinical outcomes.

Liraglutide + PYY3-36 Combination Therapy Mimics Effects of Roux-en-Y Bypass on Early NAFLD Whilst Lacking-Behind in Metabolic Improvements

Background: Treatment options for NAFLD are still limited. Bariatric surgery, such as Roux-en-Y gastric bypass (RYGB), has been shown to improve metabolic and histologic markers of NAFLD. Glucagon-like-peptide-1 (GLP-1) analogues lead to improvements in phase 2 clinical trials. We directly compared the effects of RYGB with a treatment using liraglutide and/or peptide tyrosine tyrosine 3-36 (PYY_3-36) in a rat model for early NAFLD. Methods: Obese male Wistar rats (high-fat diet (HFD)-induced) were randomized into the following treatment groups: RYGB, sham-operation (sham), liraglutide (0.4 mg/kg/day), PYY_3-36 (0.1 mg/kg/day), liraglutide+PYY_3-36, and saline. After an observation period of 4 weeks, liver samples were histologically evaluated, ELISAs and RNA sequencing + RT-qPCRs were performed. Results: RYGB and liraglutide+PYY_3-36 induced a similar body weight loss and, compared to sham/saline, marked histological improvements with significantly less steatosis. However, only RYGB induced significant metabolic improvements (e.g., adiponectin/leptin ratio 18.8 ± 11.8 vs. 2.4 ± 1.2 in liraglutide+PYY_3-36- or 1.4 ± 0.9 in sham-treated rats). Furthermore, RNA sequencing revealed a high number of differentially regulated genes in RYGB treated animals only. Conclusions: The combination therapy of liraglutide+PYY_3-36 partly mimics the positive effects of RYGB on weight reduction and on hepatic steatosis, while its effects on metabolic function lack behind RYGB.

A fast and accurate mouse model for inducing non-alcoholic steatohepatitis

Aim

This study aimed to perform a head-to-head comparison of changes during NASH progression throughout 6-11 weeks of an experiment to supply a faster nutritional model in mimicking NASH to decrease the duration and cost of in vivo studies.

Background

New therapies are urgently needed because of the growing prevalence of non-alcoholic steatohepatitis (NASH) and the lack of an effective treatment approach. Currently, dietary interventions are the most efficient options.

Methods

This study compared features of NASH in a murine model using protocol that combined special nutritional regimes based on the combination of 21.1% fat, 41% sucrose, and 1.25% cholesterol with weekly intraperitoneal injections of carbon tetrachloride (CCl4). Male C57BL/6J mice received either special compositions + CCl4 (NASH group) or standard chow diet (healthy control group) for 11 weeks. Liver histopathology based on hematoxylin and eosin (H&E) and Masson's Trichrome (TC) staining and biochemical analyses were used to assess disease progression.

Results

In C57BL/6J mice administered a high fat, high cholesterol, high sucrose diet and CCl4 for 8 weeks, steatohepatitis with pronounced hepatocyte ballooning, inflammation, steatosis, and fibrosis was observed. According to the NAFLD activity scoring system, the maximum NAS score was manifested after 8-9 weeks (NAS score: 6.75). Following this protocol also led to a significant increase in AST and ALT, total cholesterol, and total triglyceride serum levels in the NASH group.

Conclusion

Following the special nutritional regime based on high fat, cholesterol, and sucrose in combination with CCL4 injections resulted in a NASH model using C57BL/6J mice in a shorter time compared to similar studies. The obtained histopathological NASH features can be advantageous for preclinical drug testing.

Intestinal dysbiosis in nonalcoholic fatty liver disease (NAFLD): focusing on the gut-liver axis

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver disorders in humans, partly because it is closely related to metabolic disorders of the liver with increasing prevalence. NAFLD begins with hepatic lipid accumulation, which may cause inflammation and eventually lead to fibrosis in the liver. Numerous studies have demonstrated the close relationship between gut dysfunction (especially the gut microbiota and its metabolites) and the occurrence and progression of NAFLD. The bidirectional communication between the gut and liver, named the gut-liver axis, is mainly mediated by the metabolites derived from both the liver and gut through the biliary tract, portal vein, and systemic circulation. Herein, we review the effects of the gut-liver axis on the pathogenesis of NAFLD. We also comprehensively describe the potential molecular mechanisms from the perspective of the role of liver-derived metabolites and gut-related components in hepatic metabolism and inflammation and gut health, respectively. The study provides insights into the mechanisms underlying current summarizations that support the intricate interactions between a disordered gut and NAFLD and can provide novel strategies to lessen the prevalence and consequence of NAFLD.