Atorvastatin and Vitamin E Accelerates NASH Resolution by Dietary Intervention in a Preclinical Guinea Pig Model

Current strategies for nonalcoholic fatty liver disease treatment (Review)

Nonalcoholic fatty liver disease (NAFLD), the most common chronic hepatic disease, has become a leading health problem worldwide. The present review summarized the methods and mechanisms to treat NAFLD, including the Mediterranean diet, physical activity and exercise, bariatric surgery and specific therapeutic agents, including statins, peroxisome proliferator‑activated receptor agonists, cenicriviroc and farnesoid X receptor agonists. Biologically active substances, such as peptides, alkaloids, polyphenolic compounds, silymarin, antibiotics, fatty acids, vitamins, probiotics, synbiotics and lamiaceae have also demonstrated actions that combat NAFLD. Considering their different mechanisms of action, combining some of them may prove an efficacious treatment for NAFLD. In this light, the present review describes recent progress and future prospects in treating NAFLD.

Metabolic dysfunction-associated steatotic liver disease: An opportunity for collaboration between cardiology and hepatology

Altered metabolic function has many detrimental effects on the body that can manifest as cardiovascular and liver diseases. Traditional approaches to understanding and treating metabolic dysfunction-associated disorders have been organ-centered, leading to silo-type disease care. However, given the broad impact that systemic metabolic dysfunction has on the human body, approaches that simultaneously involve multiple medical specialists need to be developed and encouraged to optimize patient outcomes. In this review, we highlight how several of the treatments developed for cardiac care may have a beneficial effect on the liver and vice versa, suggesting that there is a need to target the disease process, rather than specifically target the cardiovascular or liver specific sequelae of metabolic dysfunction.

Solid dispersions of atorvastatin with Kolliphor RH40: Enhanced supersaturation and improvement in a hyperlipidemic rat model

Atorvastatin is a potent lipid-lowering drug with poor solubility and high presystemic clearance that limits its therapeutic efficacy. The aim of this study was to develop solid dispersions and micellar systems to obtain fast-dissolving atorvastatin systems that enhances their anti-hyperlipidemic effect. Solubility and wettability studies allow the development of solid dispersions with low proportions of croscarmellose sodium as hydrophilic carrier. Solid state characterization studies indicated that the addition of Kolliphor® RH40 surfactant to solid dispersions increases intermolecular hydrogen bonding between drug and polymer chains. Dissolution studies in biorelevant Fasted State Simulate Intestinal Fluid (FaSSIF pH 6.5) medium showed for atorvastatin solid dispersion a supersaturation peak of atorvastatin followed by an aggregation/precipitation process. Only the presence of a surfactant such as Kolliphor® RH40 in atorvastatin micellar system, promotes the presence of micelles that achieve delayed recrystallization. Efficacy studies were carried out using a hyperlipidemic model of rats fed with a high- fat diet. The atorvastatin micellar system at doses of 10 mg/kg, revealed a significant improvement in serum levels of total cholesterol, low-density lipoproteins, and triglycerides compared to atorvastatin raw material. This micellar system also exhibited more beneficial effects on liver steatosis, inflammation and ballooning injury.

Aberrant hepatic lipid metabolism associated with gut microbiota dysbiosis triggers hepatotoxicity of novel PFOS alternatives in adult zebrafish

Perfluorooctane sulfonate (PFOS) has been reported to induce hepatotoxicity in wildlife and humans. Novel PFOS alternatives have been widely used following restrictions on PFOS, but little is known about their potential toxicity. Here, the first comprehensive investigation on the chronic hepatotoxicity and underlying molecular mechanisms of PFOS, 6:2Cl-PFESA (F-53B), and sodium p-perfluorous nonenoxybenzene sulfonate (OBS) was carried out on adult zebrafish through a histopathological examination, biochemical measurement, and multi-omics analysis. PFOS and its alternatives caused changes in liver histopathology and liver function indices in the order of F-53B > PFOS > OBS, which was consistent with their concentration in the liver. In silico modeling and transcriptional profiles suggested that the aberrant hepatic lipid metabolism induced by F-53B and PFOS was initiated by the action on peroxisome proliferator-activated receptor γ (PPARγ), which triggered changes in downstream genes transcription and led to an imbalance between lipid synthesis and expenditure. Gut microbiome analysis provided another novel mechanistic perspective that changes in the abundance of Legionella, Ralstonia, Brevundimonas, Alphaproteobacteria, Plesiomonas, and Hyphomicrobium might link to alterations in the PPAR pathway based on their significant correlation. This study provides insight into the molecular mechanisms of hepatotoxicity induced by PFOS and its novel alternatives and highlights the need for concern about their environmental exposure risks.

Efficacy of Fibroblast Growth Factor 21 in non-alcoholic fatty liver disease in guinea pigs

Fibroblast Growth Factor 21 (FGF21) agonists have shown promising effects in preclinical models of non-alcoholic fatty liver disease (NAFLD) as well as in short-term clinical trials in patients with non-alcoholic steatohepatitis (NASH). Comparing drug formulation, dose, administration route and age, this exploratory study investigated effects of FGF21 on NAFLD-associated measures in a validated guinea pig model. In three separate studies, female guinea pigs received a high-fat diet prior to intervention with escalating doses of either recombinant native human FGF21 or a human FGF21 human recombinant analogue (FGF21/19 chimer) with an extended half-life. While no significant effects of native FGF21 on the investigated endpoints were observed, the long-acting FGF21/19 chimer significantly altered the levels of circulating lipids, increasing plasma concentrations of cholesterol (TC, LDLc and HDLc) in young guinea pigs (p<0.01 for all three parameters). Relative liver weights were reduced in FGF21/19-treated young animals (p<0.05) compared to mature animals, whereas FGF21/19 reduced body weights in both age groups (p<0.001). The FGF21/19 chimer effects on dyslipidemia, body and liver weights particularly in young animals, support an age-associated difference in the FGF21 response. The limited effects of the native human FGF21 highlights potential species-associated differences of this compound.

Vitamin C Deficiency May Delay Diet-Induced NASH Regression in the Guinea Pig

Oxidative stress is directly linked to non-alcoholic fatty liver disease (NAFLD) and the progression to steaotohepatitis (NASH). Thus, a beneficial role of antioxidants in delaying disease progression and/or accelerating recovery may be expected, as corroborated by recommendations of, e.g., vitamin E supplementation to patients. This study investigated the effect of vitamin C deficiency—often resulting from poor diets low in fruits and vegetables and high in fat—combined with/without a change to a low fat diet on NAFLD/NASH phenotype and hepatic transcriptome in the guinea pig NASH model. Vitamin C deficiency per se did not accelerate disease induction. However, the results showed an effect of the diet change on the resolution of hepatic histopathological hallmarks (steatosis, inflammation, and ballooning) (p < 0.05 or less) and indicated a positive effect of a high vitamin C intake when combined with a low fat diet. Our data show that a diet change is important in NASH regression and suggest that a poor vitamin C status delays the reversion towards a healthy hepatic transcriptome and phenotype. In conclusion, the findings support a beneficial role of adequate vitamin C intake in the regression of NASH and may indicate that vitamin C supplementation in addition to lifestyle modifications could accelerate recovery in NASH patients with poor vitamin C status.

Statins in Non-alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the primary cause of chronic liver disease. The range is extensive, including hepatocellular carcinoma, cirrhosis, fibrosis, fatty liver, and non-alcoholic steatohepatitis (NASH). NASH is a condition related to obesity, overweight, metabolic syndrome, diabetes, and dyslipidemia. It is a dynamic condition that can regress to isolated steatosis or progress to fibrosis and cirrhosis. Statins exert anti-inflammatory, proapoptotic, and antifibrotic effects. It has been proposed that these drugs could have a relevant role in NASH. In this review, we provide an overview of current evidence, from mechanisms of statins involved in the modulation of NASH to human trials about the use of statins to treat or attenuate NASH.

Differential Effects of Dietary Components on Glucose Intolerance and Non-Alcoholic Steatohepatitis

Pharmacological treatment modalities for non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) are scarce, and discoveries are challenged by lack of predictive animal models adequately reflecting severe human disease stages and co-morbidities such as obesity and type 2 diabetes. To mimic human NAFLD/NASH etiology, many preclinical models rely on specific dietary components, though metabolism may differ considerably between species, potentially affecting outcomes and limiting comparability between studies. Consequently, understanding the physiological effects of dietary components is critical for high translational validity. This study investigated the effects of high fat, cholesterol, and carbohydrate sources on NASH development and metabolic outcomes in guinea pigs. Diet groups (n = 8/group) included: low-fat low-starch (LF-LSt), low-fat high-starch (LF-HSt), high-fat (HF) or HF with 4.2%, or 8.4% sugar water supplementation. The results showed that caloric compensation in HF animals supplied with sugar water led to reduced feed intake and a milder NASH phenotype compared to HF. The HF group displayed advanced NASH, weight gain and glucose intolerance compared to LF-LSt animals, but not LF-HSt, indicating an undesirable effect of starch in the control diet. Our findings support the HF guinea pig as a model of advanced NASH and highlights the importance in considering carbohydrate sources in preclinical studies of NAFLD.

Current and Emerging Approaches for Hepatic Fibrosis Treatment

Liver fibrosis resulting from chronic liver injury is a key factor to develop liver cirrhosis and risk of hepatocellular carcinoma (HCC) which are major health burden worldwide. Therefore, it is necessary for antifibrotic therapies to prevent chronic liver disease progression and HCC development. There has been tremendous progress in understanding the mechanisms of liver fibrosis in the last decade, which has created new opportunities for the treatment of this condition. In this review, we aim to make an overview on information of different potential therapies (drug treatment, cell therapy, and liver transplantation) for the liver fibrosis and hope to provide the therapeutic options available for the treatment of liver fibrosis and discuss novel approaches.

The development of nonalcoholic steatohepatitis is subjected to breeder dependent variation in guinea pigs

Variability in disease development due to differences in strains and breeders constitutes a substantial challenge in preclinical research. However, the impact of the breeder on non-alcoholic steatohepatitis (NASH) is not yet fully elucidated. This retrospective study investigates NASH development in guinea pigs from Charles River or Envigo fed a high fat diet (20% fat, 15% sucrose, 0.35% cholesterol) for 16 or 24/25 weeks. Charles River animals displayed more severe NASH, with higher steatosis (p < 0.05 at week 16), inflammation (p < 0.05 at both week), fibrosis (p < 0.05 at week 16) and disease activity (p < 0.05 at both weeks). Accordingly, alanine and aspartate aminotransferase were increased at week 24/25 (p < 0.01). Hepatic expression of inflammatory (Ccl2, Cxcl8) and fibrotic (Pdgf, Serpine1, Col1a1) genes was also increased (p < 0.05). Differences were observed in healthy chow (4% fat, 0% sucrose, 0% cholesterol) fed animals: Envigo animals displayed higher relative liver weights (p < 0.01 at both weeks), liver cholesterol (p < 0.0001 at week 24/25) and aspartate aminotransferase (p < 0.05 at week 16), but lower levels of alkaline phosphatase (p < 0.0001 at week 24/25). These findings accentuates the importance of the breeder and its effect on NASH development and severity. Consequently, this may affect reproducibility, study comparison and limit the potential of developing novel therapies.

The effect of acetylsalicylic acid and pentoxifylline in guinea pigs with non-alcoholic steatohepatitis

Therapeutic options are urgently needed for non-alcoholic fatty liver disease (NAFLD), but development is time-consuming and costly. In contrast, drug repurposing offers the advantages of re-applying compounds that are already approved, thereby reducing cost. Acetylsalicylic acid (ASA) and pentoxifylline (PTX) have shown promise for treatment of NAFLD, but have not yet been tested in combination. Guinea pigs were fed a high-fat diet for 16 weeks and then continued on the diet while being treated with ASA, PTX or ASA+PTX for 8 weeks. Chow-fed animals served as healthy controls. Guinea pigs were CT scanned before intervention start and at intervention end. Animals without steatosis (ie NAFLD) at week 16 were excluded from the data analysis. ASA and PTX alone or in combination did not improve hepatic steatosis, ballooning, inflammation or fibrosis nor did the treatments affect liver enzymes (aminotransferases and alkaline phosphatase) or circulating lipids. Liver triglyceride levels, relative liver weight and hepatic mRNA expression of monocyte chemoattractant protein 1, interleukin 8 and platelet-derived growth factor b were nominally decreased. Thus, in the current study, treatment with ASA and PTX alone or in combination for 8 weeks did not ameliorate NASH or hepatic fibrosis in guinea pigs.

Danger signals in liver injury and restoration of homeostasis

Damage-associated molecular patterns are signalling molecules involved in inflammatory responses and restoration of homeostasis. Chronic release of these molecules can also promote inflammation in the context of liver disease. Herein, we provide a comprehensive summary of the role of damage-associated molecular patterns as danger signals in liver injury. We consider the role of reactive oxygen species and reactive nitrogen species as inducers of damage-associated molecular patterns, as well as how specific damage-associated molecular patterns participate in the pathogenesis of chronic liver diseases such as alcohol-related liver disease, non-alcoholic steatohepatitis, liver fibrosis and liver cancer. In addition, we discuss the role of damage-associated molecular patterns in ischaemia reperfusion injury and liver transplantation and highlight current studies in which blockade of specific damage-associated molecular patterns has proven beneficial in humans and mice.

Dietary Intervention Accelerates NASH Resolution Depending on Inflammatory Status with Minor Additive Effects on Hepatic Injury by Vitamin E Supplementation

Despite the lack of effective pharmacotherapy against nonalcoholic steatohepatitis (NASH) and liver fibrosis, vitamin E (vitE) supplementation and lifestyle modifications are recommended for the management of NASH due to promising clinical results. We recently reported a positive effect of supplementation with 800 IU vitE and atorvastatin on NASH resolution in guinea pigs. In the present study, we investigated the effect of high-dose vitE therapy combined with dietary intervention against progressive NASH and advanced fibrosis in the guinea pig model. Sixty-six guinea pigs received either high-fat (HF) or standard guinea pig chow diet (Control) for 25 weeks. Prior to eight weeks of intervention, HF animals were allocated into groups; dietary intervention (Chow) or dietary intervention with 2000 IU/d vitE supplementation (CvitE). Both Chow and CvitE reduced dyslipidemia, hepatic lipid accumulation and liver weight (p < 0.05), while CvitE further decreased hepatocellular ballooning (p < 0.05). Subanalyses of individual responses within intervention groups showed significant correlation between the hepatic hallmarks of NASH and lipid accumulation vs. inflammatory state (p < 0.05). Collectively, our results indicate that individual differences in sensitivity towards intervention and inflammatory status determine the potential beneficial effect of dietary intervention and high-dose vitE supplementation. Moreover, the study suggests that inflammation is a primary target in NASH treatment.

Maternal N-Acetyl Cysteine Intake Improved Glucose Tolerance in Obese Mice Offspring

Exposure to certain environmental factors during the early stages of development was found to affect health in adulthood. Among other environmental factors, oxidative stress has been suggested to be involved in fetal programming, leading to elevated risk for metabolic disorders, including type 2 diabetes; however, the possibility that antioxidant consumption during early life may affect the development of diabetes has scarcely been studied. The aim of this study was to investigate the effects of N-acetyl-l-cysteine (NAC) given during pregnancy and lactation on the susceptibility of offspring to develop glucose intolerance at adulthood. C57bl6/J mice were given NAC during pregnancy and lactation. High fat diet (HFD) was given to offspring at an age of 6 weeks for an additional 9 weeks, till the end of the study. Isolated islets of NAC-treated offspring (6 weeks old, before HFD feeding) had an increased efficacy of glucose-stimulated insulin secretion and a higher resistance to oxidative damage. Following HFD feeding, glucose tolerance and insulin sensitivity of NAC-treated offspring were improved. In addition, islet diameter was lower in male offspring of NAC-treated mice compared to their HFD-fed littermates. NAC consumption during early life improves glucose tolerance in adulthood in mice.