Potential involvement of PPAR α activation in diminishing the hepatoprotective effect of fenofibrate in NAFLD: Accuracy of non- invasive panel in determining the stage of liver fibrosis in rats

Role of liver sinusoidal endothelial cell in metabolic dysfunction-associated fatty liver disease

Liver sinusoidal endothelial cells (LSECs) are highly specialized endothelial cells that represent the interface between blood cells on one side and hepatocytes on the other side. LSECs not only form a barrier within the hepatic sinus, but also play important physiological functions such as regulating hepatic vascular pressure, anti-inflammatory and anti-fibrotic. Pathologically, pathogenic factors can induce LSECs capillarization, that is, loss of fenestra and dysfunction, which are conducive to early steatosis, lay the foundation for the progression of metabolic dysfunction-associated fatty liver disease (MAFLD), and accelerate metabolic dysfunction-associated steatohepatitis (MASH) and liver fibrosis. The unique localization, phenotype, and function of LSECs make them potential candidates for reducing liver injury, inflammation, and preventing or reversing fibrosis in the future.

Antioxidant potential of acerola by-product along the enterohepatic axis of rats fed a high-fat diet

Acerola (Malpighia emarginata DC) by-product (ABP) has bioactive compounds that can provide antioxidant and hypolipidemic effects in vivo. In this study we aimed to evaluate the antioxidant potential of ABP on oxidative damage along the enterohepatic axis of rats fed a high-fat diet for 7 weeks. In addition, we analysed the phenolic compound profile in the enterohepatic axis, and the lipid accumulation in the liver, colon and liver tissue structure of high-fat diet-fed rats treated with fenofibrate drug (100 mg/kg) or ABP (400 mg/kg) via orogastric administration in the 4th to 7th weeks of the experiment. ABP had increased antioxidant potential in vitro and presented ascorbic acid (2022.06 μg/g), carotenoid (2.63 μg/g), and total phenolic compound (5366.44 μg/g) contents. The high-fat diet-fed rats that received ABP (compared to fenofibrate treatment) presented a non-significant reduction of 9.87% in guanine oxidation product, lower relative liver weight, degree of hepatic steatosis, and aspartate aminotransferase level in their blood. ABP also provided high-fat diet-fed rats: an increased amount of total phenolic compounds in caecal digesta (946.42 µg/g), faeces (3299.07 µg/g), colon (256.15 µg/g) and hepatic tissues (454.80 µg/g); higher total antioxidant capacity in plasma and colon; and lower lipid peroxidation in plasma, colonic and hepatic tissues. The results point to the potential antioxidant activity of ABP against oxidative damage along the enterohepatic axis caused by high-fat diet intake. The ABP had a greater protective effect on the healthy liver compared to fenofibrate treatment due to its bioactive compound content.

Mechanism of homocysteine-mediated endothelial injury and its consequences for atherosclerosis

Homocysteine (Hcy) is an intermediate amino acid formed during the conversion from methionine to cysteine. When the fasting plasma Hcy level is higher than 15 μmol/L, it is considered as hyperhomocysteinemia (HHcy). The vascular endothelium is an important barrier to vascular homeostasis, and its impairment is the initiation of atherosclerosis (AS). HHcy is an important risk factor for AS, which can promote the development of AS and the occurrence of cardiovascular events, and Hcy damage to the endothelium is considered to play a very important role. However, the mechanism by which Hcy damages the endothelium is still not fully understood. This review summarizes the mechanism of Hcy-induced endothelial injury and the treatment methods to alleviate the Hcy induced endothelial dysfunction, in order to provide new thoughts for the diagnosis and treatment of Hcy-induced endothelial injury and subsequent AS-related diseases.

The Effect of Lipopolysaccharide-Stimulated Adipose-Derived Mesenchymal Stem Cells on NAFLD Treatment in High-Fat Diet-Fed Rats

Background

Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are 2 common liver diseases that currently lack effective treatment options.

Objectives

This study aimed to investigate the effect of lipopolysaccharide (LPS)-stimulated adipose-derived stem cells (ADSCs) on NAFLD treatment in an animal model.

Methods

Male Wistar rats were fed a high-fat diet (HFD) to induce NAFLD for 7 weeks. The rats were then categorized into 3 groups: Mesenchymal stem cell (MSC), MSC + LPS, and fenofibrate (FENO) groups. Liver and body weight were measured, and the expression of genes involved in fatty acid biosynthesis, β-oxidation, and inflammatory responses was assessed.

Results

Lipopolysaccharide-stimulated ADSCs were more effective in regulating liver and body weight gain and reducing liver triglyceride (TG) levels compared to the other groups. Treatment with LPS-stimulated ADSCs effectively corrected liver enzymes, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and lipid factors, including low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) values, better than treatment with both FENO and MSCs. ADSCs + LPS treatment significantly decreased transforming growth factor β (TGF-β) and genes associated with inflammatory responses. Additionally, there was a significant reduction in reactive oxygen species (ROS) levels in the rats treated with ADSCs + LPS.

Conclusions

Lipopolysaccharide-stimulated ADSCs showed potential in alleviating NAFLD by reducing inflammatory genes and ROS levels in HFD rats, demonstrating better results than treatment with ADSCs and FENO groups alone.

Impact of fenofibrate on NAFLD/NASH: A genetic perspective

Nonalcoholic fatty liver disease (NAFLD), caused by an accumulation of fat deposits in hepatocytes, prevalently affects at least one-third of the world's population. The progression of this disorder can potentially include a spectrum of consecutive stages, specifically: steatosis, steatohepatitis and cirrhosis. Fenofibrate exhibits potential therapeutic efficacy for NAFLD owing to several properties, which include antioxidant, apoptotic, anti-inflammatory and antifibrotic activity. In the present review, we discuss the direct or indirect impact of fenofibrate on genes involved at various stages in the progression of NAFLD. Moreover, we have reviewed studies that compare fenofibrate with other drugs in treating NAFLD, as well as recent clinical trials, in an attempt to identify reliable scientific and clinical evidence concerning the therapeutic effects and benefits of fenofibrate on NAFLD. Teaser.

Investigation of the Effect of Curcumin on Protein Targets in NAFLD Using Bioinformatic Analysis

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a prevalent metabolic disorder. Defects in function/expression of genes/proteins are critical in initiation/progression of NAFLD. Natural products may modulate these genes/proteins. Curcumin improves steatosis, inflammation, and fibrosis progression. Here, bioinformatic tools, gene−drug and gene-disease databases were utilized to explore targets, interactions, and pathways through which curcumin could impact NAFLD. METHODS: Significant curcumin−protein interaction was identified (high-confidence:0.7) in the STITCH database. Identified proteins were investigated to determine association with NAFLD. gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were analyzed for significantly involved targets (p < 0.01). Specificity of obtained targets with NAFLD was estimated and investigated in Tissue/Cells−gene associations (PanglaoDB Augmented 2021, Mouse Gene Atlas) and Disease−gene association-based EnrichR algorithms (Jensen DISEASES, DisGeNET). RESULTS: Two collections were constructed: 227 protein−curcumin interactions and 95 NAFLD-associated genes. By Venn diagram, 14 significant targets were identified, and their biological pathways evaluated. Based on gene ontology, most targets involved stress and lipid metabolism. KEGG revealed chemical carcinogenesis, the AGE-RAGE signaling pathway in diabetic complications and NAFLD as the most common significant pathways. Specificity to diseases database (EnrichR algorithm) revealed specificity for steatosis/steatohepatitis. CONCLUSION: Curcumin may improve, or inhibit, progression of NAFLD through activation/inhibition of NAFLD-related genes.

Network Pharmacological Analysis and Experimental Validation of the Mechanisms of Action of Si-Ni-San Against Liver Fibrosis

Background: Si-Ni-San (SNS), a commonly used traditional Chinese medicine (TCM) formula, has potency against liver diseases, such as hepatitis and non-alcoholic fatty liver disease (NAFLD). However, the therapeutic efficacy and pharmacological mechanisms of action of SNS against liver fibrosis remain largely unclear. Methods: A carbon tetrachloride (CCl4)-induced liver fibrosis mouse model was adopted for the first time to investigate the beneficial effects of SNS on liver fibrosis. The potential mechanisms of action of SNS were explored using the network pharmacology-based strategy and validated with the aid of diverse assays. Results: SNS treatment reduced collagen and ECM deposition, downregulated fibrosis-related factor (hyaluronic acid and laminin) contents in serum, maintained the morphological structure of liver tissue, and improved liver function in the liver fibrosis model. Based on network pharmacology results, apoptosis, inflammation and angiogenesis, together with the associated pathways (including VEGF, TNF, caspase, PPAR-γ and NF-κB), were identified as the mechanisms underlying the effects of SNS on liver fibrosis. Further in vivo experiments validated the significant mitigatory effects of SNS on inflammatory infiltration and pro-inflammatory cytokine contents (IFNγ, IL-1β and TGF-β1) in liver tissues of mice with liver fibrosis. SNS suppressed pathologic neovascularization as well as levels of VEGFR1, VEGF and VEGFR2 in liver tissues. SNS treatment additionally inhibited hepatic parenchyma cell apoptosis in liver tissues of mice with liver fibrosis and regulated apoptin expression while protecting L02 cells against apoptosis induced by TNF-α and Act D in vitro. Activation of hepatic stellate cells was suppressed and the balance between MMP13 and TIMP1 maintained in vitro by SNS. These activities may be associated with SNS-induced NF-κB suppression and PPAR-γ activation. Conclusion: SNS effectively impedes liver fibrosis progression through alleviating inflammation, ECM accumulation, aberrant angiogenesis and apoptosis of hepatic parenchymal cells along with inhibiting activation of hepatic stellate cells through effects on multiple targets and may thus serve as a novel therapeutic regimen for this condition.

Fenofibrate impairs liver function and structure more pronounced in old than young rats

INTRODUCTION

Since old animals are known to accumulate lipids in some organs, we compared effects of fenofibrate (FN) on systemic lipid metabolism, activity of liver marker enzymes and structure in young and old rats.

MATERIAL AND METHODS

Young and old rats were fed chow supplemented with 0.1 % or 0.5 % FN. After 30 days, intraperitoneal glucose tolerance test (IPGTT) was performed, and blood and liver samples were collected.

RESULTS

In young rats, 0.1 % FN, but not 0.5 % FN, decreased serum Chol by 74 %, and did not affect TG levels at either doses. In old rats, 0.5 % FN, but not 0.1 % FN, decreased Chol and TG level by 56 % and 49 %, respectively. In young rats, 0.1 % and 0.5 % FN increased serum activity of ALP by 227 % and 260 %, respectively, and did not affect AST and ALT activities. In old rats, only 0.5 % FN increased serum ALP activity by 150 %, respectively. In old rats, neither dose of FN affected serum AST activity, and only 0.5 % FN increased serum ALT activity by 200 %. The histological examination of liver structure revealed that both doses of FN impaired lobular architecture, expansion of bile canaliculi, and degeneration of parenchymal cells with the presence of cells containing fat droplets; administration of FN increased area occupied by collagen fibers.

CONCLUSIONS

Although 0.5 % FN decreased serum Chol concentration, it increased serum ALP activity and impaired liver structure in both in both age groups of rats. Thus, FN treatment should be under the control of liver function, especially in older patients.

CXCR1/CXCR2 antagonist G31P inhibits nephritis in a mouse model of uric acid nephropathy

The prevalence of gout is relatively high worldwide, and many gout patients suffer from uric acid nephropathy (UAN) concomitantly. ELR-CXC chemokines such as CXCL8 and CXCL1 have a elevated expression in UAN. In this research, a mouse UAN model was established for a 12 week duration, and uric acid-related crystals were observed. CXCL8(3-72)K11R/G31P (G31P) is a mutant protein of CXCL8/interleukin 8 (IL-8), which has been reported to have therapeutic efficacy in both inflammatory diseases and malignancies for it acts as a selective antagonist towards CXCR1/CXCR2. In this study, G31P-treated mice showed declined production of the blood urea nitrogen (BUN) level and urine volume in UAN mice compared with G31P-untreated UAN counterparts. In addition, G31P effectively improved renal fibrosis, and reduced uric acid accumulation and leukocyte infiltration in UAN kidneys. Furthermore, the expressions of CXCL1 and CXCL2 were reduced and the activation of NOD-like receptors protein 3 (NLRP3) was inhibited by G31P treatment. This study has demonstrated that G31P attenuates inflammatory progression in chronic UAN, and plays a renoprotective function.

Semen Brassicae ameliorates hepatic fibrosis by regulating transforming growth factor-β1/Smad, nuclear factor-κB, and AKT signaling pathways in rats

Purpose

There is no effective treatment for liver fibrosis, which is a common phase during the progression of many chronic liver diseases to cirrhosis. Previous studies found that Semen Brassicae therapy can effectively improve the clinical symptoms of patients with asthma, allergic rhinitis, and chronic lung diseases; however, its effects on liver fibrosis in rats and its possible mechanisms of action remain unclear.

Methods

Rats were injected intraperitoneally with 4% thioacetamide aqueous solution (5 mL·kg⁻¹) at a dose of 200 mg·kg⁻¹ twice a week for 8 consecutive weeks to establish the liver fibrosis model and were then treated with different concentrations of Semen Brassicae extract. After Semen Brassicae treatment, the morphology of the liver tissue was analyzed using hematoxylin and eosin and Masson’s trichrome staining, and liver index and liver fibrosis grade were calculated. Thereafter, the levels of collagen-I, collagen-III, α-SMA, transforming growth factor (TGF)-β1, p-Smad 2/3, Smad 2/3, Smad4, NF-κB-p65, p-NF-κB-p65, IL-1β, IL-6, AKT, and p-AKT were determined using Western blotting.

Results

Compared with the untreated model group, the Semen Brassicae-treated group showed significantly decreased liver function indices; expression levels of collagen-I, collagen-III, and α-SMA; and hepatic fibrosis. Further studies also showed that the expression of TGF-β1, Smad4, p-Smad 2/3/Smad 2/3, p-NF-κB-p65/NF-κB-p65, IL-1β, IL-6, and p-AKT/AKT significantly decreased after the treatment.

Conclusion

These results indicate that Semen Brassicae exhibits an anti-hepatic fibrosis effect, and the underlying mechanism of action may be related to the regulation of TGF-β1/Smad, NF-κB, and AKT signaling pathways and the reduction of extracellular matrix deposition.

Ethyl pyruvate can alleviate alcoholic liver disease through inhibiting Nrf2 signaling pathway

The effects of ethyl pyruvate (EP) on alcoholic liver disease and its related mechanism were investigated. Thirty male C57/BL6 mice were randomly divided to three groups: Control (n=10), alcoholic liver disease (ALD, n=10) and ethyl pyruvate group (EP, n=10). EP group was treated with gavage using EP (100 mg/kg) for 15 consecutive days. Control and ALD group were treated with the same volume of normal saline. After the last gavage, EP and ALD group were treated with the intraperitoneal injection of 50% alcoholic solution (10 ml/kg). After that, ALD and EP group received the gavage using alcohol for 4 weeks, while Control group received the same volume of normal saline, and blood and liver tissues were taken for detection. Results showed that in this experimental study that EP could effectively alleviate the alcoholic liver disease. The levels of alanine aminotransferase (AST), triglycerides (TG), free fatty acid (FFA) and FBG in EP group were significantly lower than those in ALD group, but the number of platelets was reversed, and the differences were statistically significant; the levels of anti-inflammatory factors (TGF-β/IL-10) and superoxide dismutase (SOD) in EP were significantly higher than those in ALP group, but the levels of pro-inflammatory factors (IL-6/TNF-α) and MDA were significantly lower than those in ALP group. EP upregulated CYP2E1, downregulated PPAR-α, nuclear factor 2 (Nrf2) and very-low density lipoprotein receptor (VLDLR), positively regulated the CYP2E1-PPAR-α-ROS signaling pathway and negatively regulated the ROS-Nrf2-VLDLR signaling pathway. EP can increase anti-inflammatory factors and decrease pro-inflammatory factors, enhance the activity of SOD and reduce FFA and TG. Moreover, it can upregulate the PPAR-α expression by negative regulation of CYP2E1-PPAR-α signaling pathway and downregulate the Nrf2 expression by negative regulation of Nrf2-VLDLR signaling pathway, thus alleviating the alcoholic liver disease.

Lingguizhugan Decoction Protects against High-Fat-Diet-Induced Nonalcoholic Fatty Liver Disease by Alleviating Oxidative Stress and Activating Cholesterol Secretion

Background

Nonalcoholic fatty liver disease (NAFLD) has become a leading cause of liver transplantation. Lingguizhugan decoction (LGZG), a classical Chinese herbal formula, has beneficial effects on NAFLD animal models. Our study examined the impact of LGZG on hepatic global transcriptome of high-fat-diet-induced NAFLD rats.

Methods

Three groups of Wistar rats were included: normal, NAFLD model, and LGZG-treated NAFLD groups. Four weeks for the treatment, liver tissues were harvested for RNA sequencing. Differentially expressed genes (DEGs) and enriched pathways were detected on hepatic global transcriptome profile. Real-time PCR validated the regulatory patterns of LGZG on NAFLD rats.

Results

DEGs between the NAFLD model and normal groups indicated the elevated peroxisome proliferator-activated receptor (PPAR) and hedgehog signaling pathways in NAFLD rats. In bile secretion pathway, genes involved in cholesterol secretion were activated by LGZG treatment. Increased expression of antioxidant OSIGN1 and decreased expression of genes (AHR, IRF2BP2, and RASGEF1B) that induce oxidative stress and inflammation were observed in NAFLD rats treated with LGZG. The regulatory patterns of LGZG treatment on these oxidative stress-related genes were confirmed by real-time PCR.

Conclusion

Our study revealed a “two-hits-targeting” mechanism of LGZG in the treatment for NAFLD: alleviating oxidative stress and activating cholesterol secretion.

Wogonin mitigates nonalcoholic fatty liver disease via enhancing PPARα/AdipoR2, in vivo and in vitro

Wogonin has been reported to attenuate hyperglycemia in diabetic mice via anti-adipogenic effect on adipocytes. The potential therapeutic role of wogonin in nonalcoholic fatty liver disease (NAFLD) remains obscure. The aim of the present study was to explore the protective effect of wogonin on NAFLD mice and cultured NCTC 1469 cells exposed to palmitate. Wogonin supplementation significantly improved metabolic parameters in NAFLD mice, including body weight, blood glucose, insulin resistance, adiponectin, blood lipids, aminotransferases and hepatic histopathology. Further research in liver tissues from NAFLD mice and NCTC 1469 cells stressed by lipotoxicity showed wogonin treatment reduced inflammatory response by lowering interleukin-6 (IL-6) and tumor necrosis factor α (TNFα), alleviated oxidative stress by preventing the accumulation of oxidative product malondialdehyde (MDA) and strengthening the anti-oxidative capacity of glutathione (GSH), Superoxide Dismutase (SOD) and Glutathione Peroxidase (GPX). In addition, wogonin repaired the lipotoxicity-induced decline of peroxisome proliferator- activated receptor α (PPARα) and adiponectin receptor 2 (AdipoR2) in hepatocytes, in vivo and in vitro. Knock-down of PPARα abolished the protective effect of wogonin on NCTC 1469 cells, including the up-regulation of AdipoR2. Taken together, the current study demonstrated wogonin might be a potential therapeutic agent for NAFLD via up-regulation of hepatic PPARα/AdipoR2.