Fat Diet-induced Nonalcoholic Fatty Liver Research Articles

Hepatoprotective Effect of Lactiplantibacillus plantarum DSR330 in Mice with High Fat Diet-Induced Nonalcoholic Fatty Liver Disease.

Lactiplantibacillus plantarum DSR330 (DSR330) has been examined for its antimicrobials production and probiotics. In this study, the hepatoprotective effects of DSR330 were examined against non-alcoholic fatty liver disease (NAFLD) in a high-fat diet (HFD)-fed C57BL/6 mouse model. To induce the development of fatty liver, a HFD was administered for five weeks, and then silymarin (positive control) or DSR330 (108 or 109 CFU/day) was administered along with the HFD for seven weeks. DSR330 significantly decreased body weight and altered serum and hepatic lipid profiles, including a reduction in triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels compared to those in the HFD group. DSR330 significantly alleviated HFD-related hepatic injury by inducing morphological changes and reducing the levels of biomarkers, including AST, ALT, and ALP. Additionally, DSR330 alleviated the expression of SREBP-1c, ACC1, FAS, ACO, PPARα, and CPT-1 in liver cells. Insulin and leptin levels were decreased by DSR330 compared to those observed in the HFD group. However, adiponectin levels were increased, similar to those observed in the ND group. These results demonstrate that L. plantarum DSR330 inhibited HFD-induced hepatic steatosis in mice with NAFLD by modulating various signaling pathways. Hence, the use of probiotics can lead to hepatoprotective effects.

Comparative analysis of the synergetic effects of Diwuyanggan prescription on high fat diet-induced non-alcoholic fatty liver disease using untargeted metabolomics

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver disorders worldwide and had no approved pharmacological treatments. Diwuyanggan prescription (DWYG) is a traditional Chinese medicine preparation composed of 5 kinds of herbs, which has been used for treating chronic liver diseases in clinic. Whereas, the synergistic mechanism of this prescription for anti-NAFLD remains unclear. In this study, we aimed to demonstrate the synergetic effect of DWYG by using the disassembled prescriptions and untargeted metabolomics research strategies. The therapeutic effects of the whole prescription of DWYG and the individual herb were divided into six groups according to the strategy of disassembled prescriptions, including DWYG, Artemisia capillaris Thunb. (AC), Curcuma longa L. (CL), Schisandra chinensis Baill. (SC), Rehmannia glutinosa Libosch. (RG) and Glycyrrhiza uralensis Fisch. (GU) groups. The high fat diets-induced NAFLD mice model was constructed to evaluate the efficacy effects of DWYG. An untargeted metabolomics based on the UPLC-QTOF-MS/MS approach was carried out to make clear the synergetic effect on the regulation of metabolites dissecting the united mechanisms. Experimental results on animals revealed that the anti-NAFLD effect of DWYG prescription was better than the individual herb group in reducing liver lipid deposition and restoring the abnormality of lipidemia. In addition, further metabolomics analysis indicated that 23 differential metabolites associated with the progression of NAFLD were identified and 19 of them could be improved by DWYG. Compared with five single herbs, DWYG showed the most extensive regulatory effects on metabolites and their related pathways, which were related to lipid and amino acid metabolisms. Besides, each individual herb in DWYG was found to show different degrees of regulatory effects on NAFLD and metabolic pathways. SC and CL possessed the highest relationship in the regulation of NAFLD. Altogether, these results provided an insight into the synergetic mechanisms of DWYG from the metabolic perspective, and also supported a scientific basis for the rationality of clinical use of this prescription.

Betulin prevents high fat diet-induced non-alcoholic fatty liver disease by mitigating oxidative stress and upregulating Nrf2 and SIRT1 in rats

Non-alcoholic fatty liver disease (NAFLD) is a common chronic hepatic disorder characterized by hepatic lipid accumulation. This study explored the effect of betulin (BE), a terpenoid with promising antioxidant, anti-inflammatory and insulin sensitizing effects, on NAFLD induced by high fat diet (HFD). Rats received HFD and BE (15 and 30 mg/kg) for 12 weeks and blood and liver samples were collected for analyses. HFD caused hyperlipidemia, cholesterol and triglycerides accumulation in the liver, hepatocellular ballooning, fibrosis, insulin resistance (IR), lipid peroxidation (LPO), and NF-kB p65 upregulation. BE ameliorated serum and liver lipids, blood glucose and insulin, liver LPO, prevented steatosis and fibrosis, suppressed NF-kB p65 and enhanced antioxidants in HFD-fed rats. BE downregulated acetyl-CoA carboxylase (ACC1) and fatty acid synthase (FAS), and upregulated Nrf2, HO-1 and SIRT1 in the liver of HFD-fed rats. In silico investigations revealed the binding affinity of BE towards FAS, NF-kB, Keap1, HO-1 and SIRT1. In conclusion, BE attenuated HFD-induced NAFLD by ameliorating hyperlipidemia, IR, lipogenesis, liver lipid accumulation, and oxidative stress. The protective effect of BE was associated with enhanced Nrf2/HO-1 signaling and SIRT1.

Bicyclol attenuates high fat diet-induced non-alcoholic fatty liver disease/non-alcoholic steatohepatitis through modulating multiple pathways in mice.

Introduction: The pathological progression of non-alcoholic fatty liver disease (NAFLD) is driven by multiple factors, and non-alcoholic steatohepatitis (NASH) represents its progressive form. In our previous studies, we found that bicyclol had beneficial effects on NAFLD/ NASH. Here we aim to investigate the underlying molecular mechanisms of the bicyclol effect on NAFLD/NASH induced by high-fat diet (HFD) feeding. Methods: A mice model of NAFLD/NASH induced by HFD-feeding for 8weeks was used. As a pretreatment, bicyclol (200mg/kg) was given to mice by oral gavage twice daily. Hematoxylin and eosin (H&E) stains were processed to evaluate hepatic steatosis, and hepatic fibrous hyperplasia was assessed by Masson staining. Biochemistry analyses were used to measure serum aminotransferase, serum lipids, and lipids in liver tissues. Proteomics and bioinformatics analyses were performed to identify the signaling pathways and target proteins. Data are available via Proteome X change with identifier PXD040233. The real-time RT-PCR and Western blot analyses were performed to verify the proteomics data. Results: Bicyclol had a markedly protective effect against NAFLD/NASH by suppressing the increase of serum aminotransferase, hepatic lipid accumulation and alleviating histopathological changes in liver tissues. Proteomics analyses showed that bicyclol remarkably restored major pathways related to immunological responses and metabolic processes altered by HFD feeding. Consistent with our previous results, bicyclol significantly inhibited inflammation and oxidative stress pathway related indexes (SAA1, GSTM1 and GSTA1). Furthermore, the beneficial effects of bicyclol were closely associated with the signaling pathways of bile acid metabolism (NPC1, SLCOLA4 and UGT1A1), cytochrome P450-mediated metabolism (CYP2C54, CYP3A11 and CYP3A25), biological processes such as metal ion metabolism (Ceruloplasmin and Metallothionein-1), angiogenesis (ALDH1A1) and immunological responses (IFI204 and IFIT3). Discussion: These findings suggested that bicyclol is a potential preventive agent for NAFLD/NASH by targeting multiple mechanisms in future clinical investigations.

Baicalin ameliorates high fat diet-induced nonalcoholic fatty liver disease in mice via adenosine monophosphate-activated protein kinase-mediated regulation of SREBP1/Nrf2/NF-κB signaling pathways.

Nonalcoholic fatty liver disease (NAFLD) is a prevalent chronic liver disease around the world, imposing severe threats on human health. Unfortunately, no clinically approved drugs are available for use as yet. Baicalin (BA) is reported to have hepatoprotective effects, and it is not clear whether BA can treat NAFLD and how. Here, a high-fat diet (HFD)-induced NAFLD mouse model was established to explore the protective roles and mechanisms of BA against HFD-induced NAFLD. Physiochemical results showed that BA exhibited significantly protective effects against HFD-induced NAFLD in mice. Liver transcriptomic analysis revealed that BA attenuated HFD-induced NAFLD via activating AMPK pathway, which was confirmed by the AMPK inhibitor Compound C. Additionally, the expression changes of AMPK downstream genes demonstrated that BA exerted ameliorative effects against NAFLD through AMPK-mediated inhibition of SREBP1 and NF-κB pathways, and activation of Nrf2 pathway. Taken together, our study reveals the protective roles of BA against HFD-caused NAFLD through AMPK-mediated modulation of SREBP1/Nrf2/NF-κB pathways, suggesting that BA has potential drug development implications. Most importantly, our study creates a paradigm through the combination of molecular biology and bioinformatics for further studies of action mechanisms of biomolecules combating diseases.

Immune response gene 1 deficiency aggravates high fat diet-induced nonalcoholic fatty liver disease via promotion of redox-sensitive AKT suppression

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder worldwide. Immune response gene 1 (IRG1) catalyzes the production of bio-active itaconate, which is actively involved in the regulation of signal transduction. A recent study has found that the expression of IRG1 was significantly down-regulated in obesity-associated fatty liver, but the potential roles of IRG1 in the development NAFLD remain unclear. The present study found that genetic deletion of IRG1 aggravated high fat diet (HFD)-induced metabolic disturbance, including obesity, dyslipidemia and insulin resistance. In addition, HFD induced more severe liver steatosis and higher serum ALT and AST level in IRG1 KO mice, which were accompanied with altered expression of genes involved in lipid uptake, synthesis and catabolism. RNA-seq and immunoblot analysis indicated that deficiency of IRG1 is associated with suppressed activation of AKT, a master metabolic regulator. Mechanistically, IRG1/itaconate enhanced the antioxidative NRF2 pathway and prevented redox-sensitive suppression of AKT. Interestingly, supplementation with 4-octyl itaconate (4-OI), a cell-permeable derivate of itaconate, alleviated HFD-induced oxidative stress, AKT suppression and liver steatosis. Therefore, IRG1 probably functions as a protective regulator in the development of NAFLD and the cell-permeable 4-OI might have potential value for the pharmacological intervention of NAFLD.

Can Zinc Supplementation Attenuate High Fat Diet-Induced Non-Alcoholic Fatty Liver Disease?

The pathogenesis of non-alcoholic fatty liver disease (NAFLD), the most prevalent chronic liver disease, is associated with zinc deficiency. Previous studies show zinc supplementation improves steatosis and glucose metabolism, but its therapeutic effects in patients with established NAFLD remain unclear. We developed an in vivo model to characterize the effects of zinc supplementation on high-fat diet (HFD) induced NAFLD and hypothesized that the established NAFLD would be attenuated by zinc supplementation. Male C57BL/6J mice were fed a control diet or HFD for 12 weeks. Mice were then further grouped into normal and zinc-supplemented diets for 8 additional weeks. Body composition and glucose tolerance were determined before and after zinc supplementation. At euthanasia, plasma and liver tissue were collected for characterization and downstream analysis. As expected, 12 weeks of HFD resulted in reduced glucose clearance and altered body composition. Eight weeks of subsequent zinc supplementation did not alter glucose handling, plasma transaminases, steatosis, or hepatic gene expression. Results from our model suggest 8-week zinc supplementation cannot reverse established NAFLD. The HFD may have caused NAFLD disease progression beyond rescue by an 8-week period of zinc supplementation. Future studies will address these limitations and provide insights into zinc as a therapeutic agent for established NAFLD.

Hepatic parenchymal cell and mitochondrial-targeted astaxanthin nanocarriers for relief of high fat diet-induced nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) is a metabolic syndrome disorder. Here, hepatic parenchymal cell and mitochondrial-targeted nanocarriers were constructed to deliver astaxanthin (AST) to liver tissue to maximize AST intervention efficiency. The hepatic parenchymal cell-targeting was achieved using galactose (Gal) conjugated onto whey protein isolate (WPI) through the Maillard reaction by recognizing asialoglycoprotein receptors specifically expressed in hepatocytes. Grafting triphenylphosphonium (TPP) onto glycosylated WPI by an amidation reaction enabled the nanocarriers (AST@TPP-WPI-Gal) to achieve dual targeting capability. The AST@TPP-WPI-Gal nanocarriers could target mitochondria in steatotic HepG2 cells with an enhanced anti-oxidative and anti-adipogenesis effect. The ability of AST@TPP-WPI-Gal to target liver tissue was verified by an NAFLD mice model, and the results showed that AST@TPP-WPI-Gal could regulate blood lipid disorders, protect liver function, and remarkably reduce liver lipid accumulation (40%) compared with that of free AST. Therefore, AST@TPP-WPI-Gal might have potential as a dual targeting hepatic agent for nutritional intervention for NAFLD.

Human milk-derived extracellular vesicles alleviate high fat diet-induced non-alcoholic fatty liver disease in mice.

Nonalcoholic fatty liver disease (NAFLD), characterized by excessive hepatic lipid accumulation, imposes serious challenges on public health worldwide. Breastfeeding has been reported to reduce the risk of NAFLD. Extracellular vesicles (EVs) are bilayer membrane vesicles released from various cells into the extracellular space, participating in multiple life processes. Whether EVs from human milk exert metabolic benefits against NAFLD is worth investigating. In this study, the EVs were isolated from human milk collected from healthy mothers and quantified. Functional analyses were performed using the NAFLD mouse model and free fatty acid (FFA)-stimulated mouse primary hepatocytes. The results showed that human milk-derived EVs could effectively alleviate high fat diet-induced hepatic steatosis and insulin resistance in mice with NAFLD via inhibiting lipogenesis and increasing lipolysis. The FFA-induced lipid accumulation was also inhibited in hepatocytes after treatment with human milk-derived EVs. Mechanistically, the human milk derived-EVs cargo (proteins and miRNAs), which linked to lipid metabolism, may be responsible for these beneficial effects. The findings of this study highlighted the therapeutic benefits of human milk-derived EVs and provided a new strategy for NAFLD treatment.

Yinchen Linggui Zhugan decoction ameliorates high fat diet-induced nonalcoholic fatty liver disease by modulation of SIRT1/Nrf2 signaling pathway and gut microbiota.

Yinchen Linggui Zhugan decoction (YLZD) is an effective and classical traditional herbal prescription for treating the nonalcoholic fatty liver disease (NAFLD) and has been proven to be effective in the regulation of lipid metabolism disorder and attenuate inflammation for a NAFLD rat model. However, the exact underlying mechanism has not been elucidated. In the current study, a NAFLD rat model was established using a high-fat diet (HFD) for 10 weeks, followed by YLZD treatment with 1.92 g/kg/day for 4 weeks to explore the mechanisms of YLZD. Our results showed that YLZD decreased the hepatic lipid deposition, restored the liver tissue pathological lesions, inhibited the expression of oxidative stress, and decreased the inflammatory cytokines levels. Meanwhile, the genes and proteins expressions of SIRT1/Nrf2 signaling pathway together with downstream factors including HO-1 and NQO1 were elevated in the YLZD treated NAFLD rats. For further elaborating the upstream mechanism, short-chain fatty acids (SCFAs) in serum and feces were measured by liquid chromatograph mass spectrometer and gas chromatograph mass spectrometer, and the differences in gut microbiota of rats in each group were analyzed through high-throughput sequencing of 16S rRNA. The results demonstrated that the contents of butyric acid (BA) and total SCFAs in YLZD-treated NAFLD rats were significantly increased in serum and feces. 16S rRNA sequencing analysis illustrated that YLZD intervention led to a modification of the gut microbiota composition, with a decrease of Oribacterium, Lactobacillus and the ratio of Firmicutes/Bacteroides, as well as the increase in SCFAs-producing bacteria such as Christensenellaceae, Clostridia, Muribaculaceae, and Prevotellaceae. Spearman rank correlation analysis indicated that BA and total SCFAs were negatively co-related with oxidative stress-related factors and inflammatory cytokines, while they were positively co-related with SIRT1/Nrf2 pathway related genes and proteins. Furthermore, in vitro study confirmed that BA effectively reduced oxidative stress by activating SIRT1/Nrf2 signaling pathway in L02 cells. Together, the present data revealed YLZD could ameliorate HFD-induced NAFLD in rats by the modulation of SIRT1/Nrf2 signaling pathway and gut microbiota.

Peroxisomal Fitness: A Potential Protective Mechanism of Fenofibrate against High Fat Diet-Induced Non-Alcoholic Fatty Liver Disease in Mice.

Non-alcoholic fatty liver disease (NAFLD) has been increasing in association with the epidemic of obesity and diabetes. Peroxisomes are single membrane-enclosed organelles that play a role in the metabolism of lipid and reactive oxygen species. The present study examined the role of peroxisomes in high-fat diet (HFD)-induced NAFLD using fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist. Eight-week-old male C57BL/6J mice were fed either a normal diet or HFD for 12 weeks, and fenofibrate (50 mg/kg/day) was orally administered along with the initiation of HFD. HFD-induced liver injury as measured by increased alanine aminotransferase, inflammation, oxidative stress, and lipid accumulation was effectively prevented by fenofibrate. Fenofibrate significantly increased the expression of peroxisomal genes and proteins involved in peroxisomal biogenesis and function. HFD-induced attenuation of peroxisomal fatty acid oxidation was also significantly restored by fenofibrate, demonstrating the functional significance of peroxisomal fatty acid oxidation. In Ppara deficient mice, fenofibrate failed to maintain peroxisomal biogenesis and function in HFD-induced liver injury. The present data highlight the importance of PPARα-mediated peroxisomal fitness in the protective effect of fenofibrate against NAFLD.

Peroxisomal Fitness: A Potential Protective Mechanism of Fenofibrate against High Fat Diet-Induced Non-Alcoholic Fatty Liver Disease in Mice

Non-alcoholic fatty liver disease (NAFLD) has been increasing in association with the epidemic of obesity and diabetes. Peroxisomes are single membrane-enclosed organelles that play a role in the metabolism of lipid and reactive oxygen species. The present study examined the role of peroxisomes in high-fat diet (HFD)-induced NAFLD using fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist.Eight-week-old male C57BL/6J mice were fed either a normal diet or HFD for 12 weeks, and fenofibrate (50 mg/kg/day) was orally administered along with the initiation of HFD.HFD-induced liver injury as measured by increased alanine aminotransferase, inflammation, oxidative stress, and lipid accumulation was effectively prevented by fenofibrate. Fenofibrate significantly increased the expression of peroxisomal genes and proteins involved in peroxisomal biogenesis and function. HFD-induced attenuation of peroxisomal fatty acid oxidation was also significantly restored by fenofibrate, demonstrating the functional significance of peroxisomal fatty acid oxidation. In Ppara deficient mice, fenofibrate failed to maintain peroxisomal biogenesis and function in HFD-induced liver injury.The present data highlight the importance of PPARα-mediated peroxisomal fitness in the protective effect of fenofibrate against NAFLD.

Network pharmacology analysis on mechanism of Jian Pi Qing Gan Yin decoction ameliorating high fat diet-induced non-alcoholic fatty liver disease and validated in vivo

Ethnopharmacological relevanceJian Pi Qing Gan Yin (JPQGY) has been used clinically to relieve non-alcoholic fatty liver disease (NAFLD) in China for decades; however, the underlying mechanisms of JPQGY remain unclear. Aim of the studyWe evaluated the effects and mechanisms of JPQGY and hepatic steatosis caused by the middle stage of 13-week-high-fat-diet-induced NAFLD in mice. Materials and methodsDifferent dosages of JPQGY (5.5, 11, and 22 g/kg/day) were administered to NAFLD mice simultaneously. Body weight, body mass index (BMI), and liver lipid- and inflammation-related serum indicators were measured enzymatically. Liver samples were stained with Oil Red O and hematoxylin and eosin (H&E). Next, we performed a network pharmacology analysis and verified eight target genes mapping to NAFLD-related lipid metabolism pathways. The mRNA/protein expression was analyzed by real-time polymerase chain reaction (PCR) and western blotting. ResultsJPQGY significantly relieved histological damage (steatosis-inflammation-fibrosis), prevented the downregulation of AMPK and Pparα, and upregulated LXRα, Srebp-1c, F4/80, Nf-κb, and Cyp2e1 in the HFD-induced NAFLD mouse model. ConclusionsThe present results suggest that chronic treatment with JPQGY ameliorated HFD-induced NAFLD in mice by targeting the first and second phases of hepatic steatosis by stimulating the AMPK/PPARα pathway and inhibiting the LXRα/Srebp1/Nf-κb pathway. Our findings provide evidence that supports the clinical use of this formula for high-fat diet-induced fatty liver disease.

Polyene Phosphatidylcholine Ameliorates High Fat Diet-Induced Non-alcoholic Fatty Liver Disease via Remodeling Metabolism and Inflammation.

Recent years have witnessed a rise in the morbidity of non-alcoholic fatty liver disease (NAFLD), in line with the global outbreak of obesity. However, effective intervention strategy against NAFLD is still unavailable. The present study sought to investigate the effect and mechanism of polyene phosphatidylcholine (PPC), a classic hepatoprotective drug, on NAFLD induced by high fat diet (HFD). We found that PPC intervention reduced the mass of liver, subcutaneous, epididymal, and brown fats in HFD mice. Furthermore, PPC supplementation significantly mitigated liver steatosis and improved glucose tolerance and insulin sensitivity in HFD mice, which was accompanied by declined levels of hepatic triglyceride, serum triglyceride, low density lipoprotein, aspartate aminotransferase, and alanine aminotransferase. Using transcriptome analysis, there were 1,789 differentially expressed genes (| fold change | ≥ 2, P < 0.05) including 893 upregulated genes and 896 downregulated genes in the HFD group compared to LC group. A total of 1,114 upregulated genes and 1,337 downregulated genes in HFD + PPC group were identified in comparison to HFD group. With the help of Gene Ontology (GO) analysis, these differentially expressed genes between HFD+PPC and HFD group were discovered related to “lipid metabolic process (GO: 0006629),” “lipid modification (GO: 0030258),” and “lipid homeostasis (GO: 0055088)”. Though Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, we found pathways associated with hepatic homeostasis of metabolism and inflammation. Notably, the pathway “Non-alcoholic fatty liver disease (mmu04932)” (P-value = 0.00698) was authenticated in the study, which may inspire the potential mechanism of PPC to ameliorate NAFLD. The study also found that lipolysis, fatty acid oxidation, and lipid export associated genes were upregulated, while the genes in uptake of lipids and cholesterol synthesis were downregulated in the liver of HFD mice after PPC supplementation. Interestingly, PPC attenuated the metabolic inflammation via inhibiting pro-inflammatory macrophage in the livers of mice fed by HFD. In summary, this study demonstrates that PPC can ameliorate HFD-induced liver steatosis via reprogramming metabolic and inflammatory processes, which inspire clues for further clarifying the intervention mechanism of PPC against NAFLD.

Tangeretin improves hepatic steatosis and oxidative stress through the Nrf2 pathway in high fat diet-induced nonalcoholic fatty liver disease mice.

Nonalcoholic liver disease (NAFLD) is a pathological condition characterized by excessive fat deposition in the liver, and NAFLD usually has a close relationship with obesity or metabolic syndrome. Currently, oxidative stress is considered as an important risk factor in the progression of NAFLD, therefore, effective amelioration of oxidative stress has emerged as a promising way to improve NAFLD. Tangeretin is a natural compound having various pharmacological activities including antioxidation and hepatoprotection. However, whether tangeretin is able to improve NAFLD through reducing hepatic oxidative stress is rarely reported. In our work, the preventive effects of tangeretin on a NAFLD mouse model induced by a high fat (HF) diet were studied. The results exhibited that tangeretin supplementation observably slowed down NAFLD progression through alleviation of metabolic indexes such as glucose tolerance, serum lipid levels and inflammatory factors, hepatic oxidative stress as well as steatosis. qRT-PCR showed that tangeretin supplementation increased the nuclear factor erythroid-2-related factor 2 (Nrf2) expression and then upregulated the expression of its downstream factors including HO-1, GCLC, NQO1 and GSTA2. Furthermore, the expression of the hepatic nucleus, Nrf2, HO-1 and GCLC, was also seen to be significantly enhanced in WB analysis. Taken together, this study implies that tangeretin might alleviate NAFLD through lowering oxidative stress in the liver by partial modulation of the Nrf2 pathway. Our study provided theoretical support that tangeretin could be used as a dietary therapy for obesity related-NAFLD or related metabolic syndrome.

Comparison of the Improvement Effect of Deep Ocean Water with Different Mineral Composition on the High Fat Diet-Induced Blood Lipid and Nonalcoholic Fatty Liver Disease in a Mouse Model.

Accumulated lipid droplets in liver cause nonalcoholic fatty liver disease (NAFLD). Deep ocean water (DOW) containing high levels of magnesium, calcium, and potassium, etc. was proven to suppress hepatic lipid in obese rats fed high fat diet in the previous study. However, the effect of mineral compositions of DOW on the prevention of NAFLD is still unclear. This study removed calcium and potassium from DOW for modulating the mineral composition, and further compared the effects of DOW (D1(Mg + Ca + K)), DOW with low potassium (D2(Mg + Ca)), and DOW with low calcium and potassium (D3(Mg)) on the prevention of NAFLD in the mice model fed with high fat diet. In these results, DOW with high magnesium levels reduced serum and liver triglyceride and cholesterol levels and serum AST and ALT activities. However, when the calcium and/or potassium minerals were removed from DOW, the effects of reduction of triglyceride level, inhibition of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and peroxisome proliferator-activated receptor-alpha (PPAR-α) expressions, and activation of superoxide dismutase, catalase, and glutathione reductase activities would be weaker. In conclusion, DOW including magnesium, calcium and potassium minerals has the strongest preventive effect on NAFLD in a mouse model by increasing the antioxidant system and inhibiting fatty acid biosynthesis.

Targeting Them1 for the Management of Obesity‐Related Disorders

Background Thioesterase superfamily member 1 (Them1; synonyms acyl-CoA thioesterase 11 and StarD14) is a fatty acyl-CoA thioesterase that hydrolyzes long-chain fatty acyl-CoAs into free fatty acids plus CoASH. Genetic disruption of Them1 in mice leads to increased energy expenditure, along with resistance to high fat diet-induced obesity, diabetes and non-alcoholic fatty liver disease. Them1 is comprised of a N-terminal enzymatic domain linked to a C-terminal steroidogenic acute regulatory protein-related lipid transfer (START) domain that can allosterically modulate enzymatic activity. Taken together, these findings suggest that chemical inhibition of Them1 could be leveraged in the management of obesity-related disorders. Aim This study was designed to develop a small molecule inhibitor that targets Them1 activity. Methods Recombinant Them1 protein was expressed in E. coli and purified using a N-terminal His-tag. A fluorescence-based assay to detect free CoASH liberated by the activity of Them1 was optimized and miniaturized into 384-well plates. A high-throughput screen utilizing a highly diverse small molecule library (360,705 compounds) was conducted to identify small molecule inhibitors targeting Them1 activity. The threshold for small molecule inhibitors was set to normalized percent inhibition > 30 and z-score < -3. To select Them1-specific small molecule inhibitors, a counter screen was conducted targeting other Acot isoforms, as well as a truncated Them1 containing only the enzymatic domain (i.e. lacking the START domain). To further improve the potency of small molecules to inhibit Them1 activity, initial structure activity relationship (SAR) expansion was performed. Biomolecular microscale thermophoresis assays were utilized to determine binding affinities of small molecule inhibitors to Them1. Results 330 small molecules were identified from the high-throughput screen (hit rate 0.09%). Ten small molecules derived from the counter screen showed specificity toward inhibiting Them1 activity either through the enzymatic (3 compounds; IC50: 4 – 10 μM) or START (7 compounds; IC50: 6 – 20 μM) domains. SAR analyses revealed molecular features that influenced the IC50 values for selected small molecules. Three small molecules exhibited Kd values in the low μM range. Conclusions We have identified small molecule inhibitors targeting Them1 activity. An optimized small molecule inhibitor targeting Them1 activity should become an attractive candidate for the pharmacologic management of obesity-related disorders.

Characteristics of bile acid composition in high fat diet-induced nonalcoholic fatty liver disease in obese diabetic rats.

Bile acid has attracted attention as a signal transmission molecule in energy metabolism. Although a high-fat diet (HFD) or obesity is known to increase hepatic fat content and alter bile acid composition, the changes in bile acid composition due to HFD or obesity remain to be elucidated. We sought to examine the bile acid composition in high fat diet-induced non-alcoholic fatty liver disease (NAFLD) in obese diabetic rats. Eight-week-old male spontaneously diabetic Torii fatty (SDTF) rats or control rats were fed an HFD. Twelve weeks post the commencement of HFD, serum and hepatic bile acid compositions and serum GLP-1 levels, which is stimulated by the secondary bile acid deoxycholic acid (DCA), were measured. The correlation between the bile acid composition and serum GLP-1 levels was also examined. While serum and hepatic levels of cholic acid (CA), a primary bile acid, tended to decrease in HFD-fed control rats, they were significantly decreased in HFD-fed SDTF rats. Hepatic CYP8B1, which plays a role in CA synthesis, the mRNA levels were significantly decreased in HFD-fed control and SDTF rats. In contrast, while serum and hepatic DCA levels were not changed in HFD-fed control rats, they were decreased in HFD-fed SDTF rats. Hepatic DCA/CA did not change in HFD-fed SDTF rats, but significantly increased in HFD-fed control rats. While serum GLP-1 levels were not changed in SDTF rats, they were significantly increased in HFD-fed control rats. Hepatic DCA/CA tended to correlate with serum GLP-1 levels, which tended to negatively correlate with the hepatic triglyceride content in SDTF rats. These results indicate that relatively increased DCA might contribute to an increase in serum GLP-1 levels, which inhibits hepatic steatosis in NAFLD.

CD38 Deficiency Protects Mice from High Fat Diet-Induced Nonalcoholic Fatty Liver Disease through Activating NAD+/Sirtuins Signaling Pathways-Mediated Inhibition of Lipid Accumulation and Oxidative Stress in Hepatocytes.

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation in hepatocytes. CD38 was initially identified as a lymphocyte surface antigen and then has been found to exist in a variety of cell types. Our previous studies showed that CD38-/- mice were resistant to high-fat diet (HFD)-induced obesity. However, the role and mechanism of CD38 in HFD-induced NAFLD is still unclear. Here, we reported that CD38-/- mice significantly alleviated HFD-induced hepatic steatosis. HFD or oleic acid (OA) remarkably increased the mRNA and protein expressions of CD38 in mouse hepatic tissues and primary hepatocytes or hepatic cell lines in vitro and in vivo, suggesting that CD38 might play a role in HFD-induced hepatic steatosis. We observed that CD38 deficiency markedly decreased HFD- or OA-induced the lipid accumulation and oxidative stress in CD38-/- livers or primary hepatocytes, respectively. In contrast, overexpression of CD38 in Hep1-6 cells aggravated OA-induced lipid accumulation and oxidative stress. Furthermore, CD38 deficiency markedly inhibited HFD- or OA-induced the expressions of NOX4, and increased the expression of PPARα, CPT1, ACOX1 and SOD2 in liver tissue and hepatocytes from CD38-/- mice, indicating that CD38 deficiency-mediated the enhancement of fatty acid oxidation and the inhibition of oxidative stress contributed to protecting NAFLD. More importantly, Ex527 (Sirt1 inhibitor) and 3-TYP (Sirt3 inhibitor) significantly enhanced OA-induced lipid accumulation and oxidative stress in CD38-/- primary hepatocytes, suggesting that the anti-lipid accumulation of CD38 deficiency might be dependent on NAD/Sirtuins-mediated enhancement of FAA β-oxidation and suppression of oxidative stress in hepatocytes. In conclusion, we demonstrated that CD38 deficiency protected mice from HFD-induced NAFLD by reducing lipid accumulation and suppressing oxidative stress via activating NAD/Sirtuins signaling pathways.

Triclosan leads to dysregulation of the metabolic regulator FGF21 exacerbating high fat diet-induced nonalcoholic fatty liver disease.

Triclosan (TCS), employed as an antiseptic and disinfectant, comes into direct contact with humans through a plethora of consumer products and its rising environmental release. We have demonstrated that TCS promotes liver tumorigenesis in mice, yet the biological and molecular mechanisms by which TCS exerts its toxicity, especially in early stages of liver disease, are largely unexplored. When mice were fed a high-fat diet (HFD), we found that fatty liver and dyslipidemia are prominent early signs of liver abnormality induced by TCS. The presumably protective HFD-induced hepatic expression of the metabolic regulator fibroblast growth factor 21 (FGF21) was blunted by TCS. TCS-altered Fgf21 expression aligned with aberrant expression of genes encoding metabolic enzymes manifested as profound systemic metabolic changes that disturb homeostasis of amino acids, fatty acids, and glucose. Using a type 1 diabetic animal model, TCS potentiates and accelerates the development of steatohepatitis and fibrosis, accompanied by increased levels of hepatic lipid droplets and oxidative stress. Analysis of fecal samples revealed that HFD-fed mice exhibited a reduction in fecal species richness, and that TCS further diminished microbial diversity and shifted the bacterial community toward lower Bacteriodetes and higher Firmicutes, resembling changes in microbiota composition in nonalcoholic steatohepatitis (NASH) patients. Using reverse-genetic approaches, we demonstrate that, along with HFD, TCS induces hepatic steatosis and steatohepatitis jointly regulated by the transcription factor ATF4 and the nuclear receptor PPARα, which participate in the transcriptional regulation of the Fgf21 gene. This study provides evidence linking nutritional imbalance and exposure to TCS with the progression of NASH.