Efficacy of Dietary Lipid Control in Healing High-Fat and High-Cholesterol Diet-Induced Fibrotic Steatohepatitis in Rats

Beneficial Effects of Dietary Nitrite on a Model of Nonalcoholic Steatohepatitis Induced by High-Fat/High-Cholesterol Diets in SHRSP5/Dmcr Rats: A Preliminary Study

Nonalcoholic steatohepatitis (NASH) is a chronic liver disease that leads to liver cirrhosis and hepatocellular carcinoma. Endothelial dysfunction caused by hepatic lipotoxicity is an underlying NASH pathology observed in the liver and the cardiovascular system. Here, we evaluated the effect of dietary nitrite on a rat NASH model. Stroke-prone, spontaneously hypertensive 5/Dmcr rats were fed a high-fat/high-cholesterol diet to develop the NASH model, with nitrite or captopril (100 mg/L, each) supplementation in drinking water for 8 weeks. The effects of nitrite and captopril were evaluated using immunohistochemical analyses of the liver and heart tissues. Dietary nitrite suppressed liver fibrosis in the rats by reducing oxidative stress, as measured using the protein levels of nicotinamide adenine dinucleotide phosphate oxidase components and inflammatory cell accumulation in the liver. Nitrite lowered the blood pressure in hypertensive NASH rats and suppressed left ventricular chamber enlargement. Similar therapeutic effects were observed in a captopril-treated rat NASH model, suggesting the possibility of a common signaling pathway through which nitrite and captopril improve NASH pathology. In conclusion, dietary nitrite attenuates the development of NASH with cardiovascular involvement in rats and provides an alternative NASH therapeutic strategy.

Is a Ketogenic Diet Superior to a High-Fat, High-Cholesterol Diet Regarding Testicular Function and Spermatogenesis?

The study aimed to determine effects of a ketogenic diet on metabolic dysfunction, testicular antioxidant capacity, apoptosis, inflammation, and spermatogenesis in a high-fat and high-cholesterol diet-induced obese mice model. Forty-two male C57BL/6 mice were fed either a normal diet (NC group) or a high-fat and high-cholesterol (HFC) diet (HFC group) for 16 weeks, and mice from the HFC group were later randomly divided into two groups: the first were maintained on the original HFC diet, and the second were fed a medium-chain triacylglycerol (MCT)-based ketogenic diet for 8 weeks (KD group). A poor semen quality was observed in the HFC group, but this was eliminated by the ketogenic diet. Both the HFC and KD groups exhibited enhanced apoptosis protein expressions in testis tissue, including caspase 3 and cleaved PARP, and higher inflammation protein expressions, including TNF-α and NF-κB. However, the KD group exhibited a statistically-significant reduction in lipid peroxidation and an increased glutathione peroxidase level as compared with the HFC group. The HFC diet induced obesity in mice, which developed body weight gain, abnormal relative organ weights, metabolic dysfunction, and liver injury. Overall, the results showed that a ketogenic diet attenuated oxidative stress and improved the semen quality reduced by the HFC diet.

L-citrulline inhibits body weight gain and hepatic fat accumulation by improving lipid metabolism in a rat nonalcoholic fatty liver disease model

BACKGROUND

Body weight gain is a social issue all over the world. When body weight increased, hepatic fat accumulation also increased and it causes fatty liver disease. Therefore, developing a new treatment method and elucidating its mechanism is necessary. L-citrulline (L-Cit) is a free amino acid found mainly in watermelon. No reports regarding its effects on the improvement of hepatic steatosis and fibrogenesis are currently available. The aim of this study was to clarify the effect and the mechanism of L-Cit on inhibition of body weight gain and hepatic fat accumulation in high-fat and high-cholesterol fed SHRSP5/Dmcr rats.

METHODS

L-Cit or water (controls) was administered to six-week-old male SHRSP5/Dmcr rats by gavage for nine weeks. We recorded the level of body weight and food intake while performing the administration and sacrificed rats. After that, the blood and lipid metabolism-related organs and tissues were collected and analyzed.

RESULTS

L-Cit treatment reduced body weight gain and hepatic TC and TG levels, and serum levels of AST and ALT. L-Cit enhanced AMPK, LKB1, PKA, and hormone-sensitive lipase (HSL) protein phosphorylation levels in the epididymal fat. L-Cit treatment improved steatosis as revealed by HE staining of liver tissues and enhanced AMPK and LKB1 phosphorylation levels. Moreover, activation of Sirt1 was higher, while the liver fatty acid synthase (FAS) level was lower. Azan staining of liver sections revealed a reduction in fibrogenesis following L-Cit treatment. Further, the liver levels of TGF-β, Smad2/3, and α-SMA, fibrogenesis-related proteins and genes, were lower in the L-Cit-treated group.

CONCLUSIONS

From the results of analysis of the epididymal fat and the liver, L-Cit inhibits body weight gain and hepatic fat accumulation by activating lipid metabolism and promoting fatty acid β-oxidation in SHRSP5/Dmcr rats.

Effect of bicyclol on blood biomarkers of NAFLD: a systematic review and meta-analysis

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is a global epidemic without effective therapeutic agents in the clinic. This meta-analysis aimed to assess the efficacy of the marketed hepatoprotectant bicyclol at improving blood biomarkers in patients with NAFLD.

DESIGN

Electronic databases were searched for randomised controlled trials (RCTs) published up to August 2020 using bicyclol to treat NAFLD. The risk of bias, quality of evidence and publication bias were evaluated. Blood biomarkers, including alanine transaminase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), triglyceride (TG) and total cholesterol (TC), were analysed using Review Manager V.5.3 software. Outcomes with significant heterogeneity (I² ≥75%) were divided into the bicyclol monotherapy subgroup and combination treatment subgroup.

RESULTS

Twelve RCTs involving 1008 patients were finally included. No serious adverse events were reported in the bicyclol-treated groups. The total effective rate of bicyclol intervention for NAFLD was significantly higher than that of the control group. The decreases in the levels of AST (mean difference (MD) = -15.20; 95% CI -20.51 to -9.90; I²=74%), TBIL (MD = -1.72; 95% CI -2.72 to -0.72; I²=0%) and TC (MD = -0.52; 95% CI -0.70 to -0.34; I²=67%) treated by bicyclol were significantly higher than those in the control group. When a high heterogeneity existed (I² ≥75%), subgroup analyses were conducted and revealed significantly decreased ALT levels (MD = -34.07; 95% CI -36.70 to -31.43; I²=0%) merely in the bicyclol monotherapy subgroup, while TG level (MD = -0.39; 95% CI -0.45 to -0.33; I²=0%) was decreased in the bicyclol combination therapy subgroup.

CONCLUSIONS

The study presents the evidence of bicyclol monotherapy and/or combination therapy for improving liver function and blood lipid biomarkers in patients with NAFLD. This preliminary study predicts that bicyclol might be an alternative drug for NAFLD therapy in the future.

High-fat and high-cholesterol diet decreases phosphorylated inositol-requiring kinase-1 and inhibits autophagy process in rat liver

Precise molecular pathways involved in the progression of non-alcoholic steatohepatitis (NASH) remain to be elucidated. As Mallory–Denk bodies were occasionally observed in the enlarged hepatocytes in NASH model rat (SHRSP5/Dmcr) fed high-fat and high-cholesterol (HFC) diet, we aimed to clarify the roles of autophagy and endoplasmic reticulum (ER) stress in NASH progression. Male SHRSP5/Dmcr were randomly divided into 4 groups. Two groups were fed a control diet; the other two groups were fed a HFC diet for 2 and 8 weeks, respectively. The HFC diet increased the autophagy-related proteins levels and microtubule-associated protein 1 light chain 3-II/I ratio after 2 and 8 weeks, respectively. However, regarding ER stress-related proteins, the HFC diet decreased the levels of phosphorylated (p-) inositol-requiring kinase-1 (p-IRE-1) and p-protein kinase RNA-like ER kinase after 2 weeks. Additionally, the HFC diet increased anti-ubiquitin-positive cells and the level of the autophagy substrate p62, suggesting that the HFC diet induced dysfunction in ubiquitin-dependent protein degradation pathways. In conclusion, the HFC diet arrested the autophagy process in the liver; this was particularly associated with decreases in p-IRE-1 expression.

Liraglutide Decreases Hepatic Inflammation and Injury in Advanced Lean Non-Alcoholic Steatohepatitis

Although commonly associated with obesity, non-alcoholic fatty liver disease (NAFLD) is also present in the lean population representing a unique disease phenotype. Affecting 25% of the world's population, NAFLD is associated with increased mortality especially when progressed to non-alcoholic steatohepatitis (NASH). However, no approved pharmacological treatments exist. Current research focuses mainly on NASH associated with obesity, leaving the effectiveness of promising treatments in lean NASH virtually unknown. This study therefore aimed to evaluate the effect of liraglutide (glucagon-like peptide 1 analogue) and dietary intervention, alone and in combination, in guinea pigs with non-obese NASH. After 20 weeks of high-fat feeding (20% fat, 15% sucrose, 0.35% cholesterol), 40 female guinea pigs were block-randomized based on weight into four groups receiving one of four treatments for 4 weeks: continued high-fat diet (HF, control), high-fat diet and liraglutide treatment (HFL), chow diet (4% fat, 0% sucrose, 0% cholesterol; HFC) or chow diet and liraglutide treatment (HFCL). High-fat feeding induced NASH with severe fibrosis. Liraglutide decreased inflammation (p < 0.05) and hepatocyte ballooning (p < 0.05), while increasing hepatic α-tocopherol (p = 0.0154). Dietary intervention did not improve liver histopathology significantly, but decreased liver weight (p = 0.004), plasma total cholesterol (p = 0.0175), LDL-cholesterol (p = 0.0063), VLDL-cholesterol (p = 0.0034), hepatic cholesterol (p < 0.0001) and increased hepatic vitamin C (p = 0.0099). Combined liraglutide and dietary intervention induced a rapid weight loss, necessitating periodical liraglutide dose adjustment/discontinuation, limiting the strength of the findings from this group. Collectively, this pre-clinical study supports the beneficial effect of liraglutide on NASH and extends this notion to lean NASH.

Bile acid detoxifying enzymes limit susceptibility to liver fibrosis in female SHRSP5/Dmcr rats fed with a high-fat-cholesterol diet

During middle age, women are less susceptible to nonalcoholic steatohepatitis (NASH) than men. Thus, we investigated the underlying molecular mechanisms behind these sexual differences using an established rat model of NASH. Mature female and male stroke-prone spontaneously hypertensive 5/Dmcr rats were fed control or high-fat-cholesterol (HFC) diets for 2, 8, and 14 weeks. Although HFC-induced hepatic fibrosis was markedly less severe in females than in males, only minor gender differences were observed in expression levels of cytochrome P450 enzymes (CYP)7A1, CYP8B1 CYP27A1, and CYP7B1, and multidrug resistance-associated protein 3, and bile salt export pump, which are involved in fibrosis-related bile acid (BA) kinetics. However, the BA detoxification-related enzymes UDP-glucuronosyltransferase (UGT) and sulfotransferase (SULT) 2A1, and the nuclear receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR), were strongly suppressed in HFC-fed males, and were only slightly changed in HFC-diet fed females. Expression levels of the farnesoid X receptor and its small heterodimer partner were similarly regulated in a gender-dependent fashion following HFC feeding. Hence, the pronounced female resistance to HFC-induced liver damage likely reflects sustained expression of the nuclear receptors CAR and PXR and the BA detoxification enzymes UGT and SULT.

A High-Fat and High-Cholesterol Diet Induces Cardiac Fibrosis, Vascular Endothelial, and Left Ventricular Diastolic Dysfunction in SHRSP5/Dmcr Rats

AIM

Non-alcoholic steatohepatitis (NASH) increases cardiovascular risk regardless of risk factors in metabolic syndrome. However, the intermediary factors between NASH and vascular disease are still unknown because a suitable animal model has never been established. The stroke-prone (SP) spontaneously hypertensive rat, SHRSP5/Dmcr, simultaneously develops hypertension, acute arterial lipid deposits in mesenteric arteries, and NASH when feed with a high-fat and high-cholesterol (HFC) diet. We investigated whether SHRSP5/Dmcr affected with NASH aggravates the cardiac or vascular dysfunction.

METHOD

Wister Kyoto and SHRSP5/Dmcr rats were divided into 4 groups of 5 rats each, and fed with a SP or HFC diet. After 8 weeks of HFC or SP diet feeding, glucose and insulin resistance, echocardiography, blood biochemistry, histopathological staining, and endothelial function in aorta were evaluated.

RESULTS

We demonstrate that SHRSP5/Dmcr rats fed with a HFC diet presented with cardiac and vascular dysfunction caused by cardiac fibrosis, endothelial dysfunction, and left ventricular diastolic dysfunction, in association with NASH and hypertension. These cardiac and vascular dysfunctions were aggravated and not associated with the presence of hypertension, glucose metabolism disorder, and/or obesity.

CONCLUSIONS

SHRSP5/Dmcr rats may be a suitable animal model for elucidating the organ interaction between NASH and cardiac or vascular dysfunction.

FOXO transcription factors protect against the diet-induced fatty liver disease

Forkhead O transcription factors (FOXOs) have been implicated in glucose and lipid homeostasis; however, the role of FOXOs in the development of nonalcoholic fatty liver disease (NAFLD) is not well understood. In this study, we designed experiments to examine the effects of two different diets-very high fat diet (HFD) and moderately high fat plus cholesterol diet (HFC)-on wildtype (WT) and liver-specific Foxo1/3/4 triple knockout mice (LTKO). Both diets induced severe hepatic steatosis in the LTKO mice as compared to WT controls. However, the HFC diet led to more severe liver injury and fibrosis compared to the HFD diet. At the molecular levels, hepatic Foxo1/3/4 deficiency triggered a significant increase in the expression of inflammatory and fibrotic genes including Emr1, Ccl2, Col1a1, Tgfb, Pdgfrb, and Timp1. Thus, our data suggest that FOXO transcription factors play a salutary role in the protection against the diet-induced fatty liver disease.