Nonalcoholic Fatty Liver Disease Induced by High-Fat Diet in C57bl/6 Models

Emerging Insights into the Role of BDNF on Health and Disease in Periphery

Brain-derived neurotrophic factor (BDNF) is a growth factor that promotes the survival and growth of developing neurons. It also enhances circuit formation to synaptic transmission for mature neurons in the brain. However, reduced BDNF expression and single nucleotide polymorphisms (SNP) are reported to be associated with functional deficit and disease development in the brain, suggesting that BDNF is a crucial molecule for brain health. Interestingly, BDNF is also expressed in the hypothalamus in appetite and energy metabolism. Previous reports demonstrated that BDNF knockout mice exhibited overeating and obesity phenotypes remarkably. Therefore, we could raise a hypothesis that the loss of function of BDNF may be associated with metabolic syndrome and peripheral diseases. In this review, we describe our recent finding that BDNF knockout mice develop metabolic dysfunction-associated steatohepatitis and recent reports demonstrating the role of one of the BDNF receptors, TrkB-T1, in some peripheral organ functions and diseases, and would provide an insight into the role of BDNF beyond the brain.

Ethyl acetate fraction of oregano seed protects non-alcoholic fatty liver in high-fat diet-induced obese mice through modulation of Srebp-1c

Oregano (Origanum vulgare) seed is used as spices and is known to have anti-inflammatory, antibacterial, and antioxidant effects. The anti-fatty liver effects of oregano seed ethyl acetate (OSEA) were evaluated in high-fat diet (HFD)-induced obese mice. OSEA was orally administered with HFD for 10 weeks. The body weight, aspartate aminotransferase, alanine aminotransferase, cholesterol, triglyceride, and low-density lipoprotein levels in the HFD with 100 mg/kg of OSEA significantly decreased by approximately 1.21-, 1.44-, 2.12-, 1.12-, 1.05, and 1.59 times, respectively, while high-density lipoprotein levels increased by approximately 1.05 times compared to those in the HFD group (p < .05). In addition, the distribution of liver fat in the HFD with 100 mg/kg OSEA (OSEA 100) group decreased significantly (p < .05). Therefore, OSEA supplementation can ameliorate fatty liver disease and reduce the accumulation of triglycerides in adipose tissue. The expression of genes involved in liver fat accumulation, such as sterol regulatory element-binding protein-1c (Srebp-1c), fatty acid synthase (Fas), stearoyl-CoA desaturase-1 (Scd1), and acetyl-CoA carboxylase 1 (Acc1), significantly decreased in OSEA 100 by approximately 2.6-, 1.74-, 1.89-, and 1.56-times, respectively (p < .05). Therefore, OSEA may modify obesity and liver fat accumulation by regulating the expression of genes involved in lipid metabolism.

Chaenomeles sinensis (Thouin) Koehne fruit polyphenols alleviate high-fat diet-induced obesity and liver steatosis by improving lipid metabolism in mice

Chaenomeles sinensis (Thouin) Koehne fruit is a rich source of medicinally and nutritionally important natural phytochemicals that benefit human health. Based on the information provided, we hypothesized that Chaenomeles sinensis (Thouin) Koehne fruit polyphenols (CSFP) possessed in vivo protective effect of on high-fat diet (HFD)-induced obesity and hepatic steatosis. Specific pathogen-free male C57BL/6J mice were randomly divided into 3 groups and fed with a low-fat diet, HFD, or HFD supplemented with CSFP by intragastric administration for 14 weeks. Obesity-related biochemical indexes and hepatic gene expression profile were determined. The findings of this study demonstrated notable reductions in body weight gain, serum triglycerides, total cholesterol, low-density lipoprotein cholesterol, and steatosis grade in the group supplemented with CSFP compared with the HFD group. Gene expression analysis provided insights into the molecular mechanisms, demonstrating that CSFP downregulated the expression of key genes involved in lipogenesis (e.g., Fas, Fads2, Scd1) and upregulated the genes associated with fatty acid oxidation (e.g., Pparα, Cpt1a, Acox1), while also suppressing genes implicated in cholesterol homeostasis (e.g., HMGCoR, Insig1, AdipoR2). These molecular changes suggest that CSFP exerts protective effects by modulating hepatic lipid metabolism pathways, thereby mitigating the metabolic derangements associated with HFD-induced obesity and hepatic steatosis.

Reduced Branched-Chain Amino Acid Intake Improved High-Fat Diet-Induced Nonalcoholic Fatty Pancreas Disease in Mice

OBJECTIVE

To explore the effects of branched-chain amino acids (BCAAs) on nonalcoholic fatty pancreas disease (NAFPD) and its possible mechanism in high-fat diet (HFD) induced mice.

MATERIALS AND METHODS

Pancreatic morphology and lipid infiltration was assessed by hematoxylin-eosin staining and immunohistochemistry, and lipid levels in the pancreas were determined using colorimetric enzymatic method. Relevant mechanism was investigated using western blotting and biochemical test.

RESULTS

In HFD-fed mice, dietary BCAAs restriction could attenuate body weight increase, improve glucose metabolism, and reduce excessive lipid accumulation in the pancreas. Furthermore, expression of AMPKα and downstream uncoupling protein 1 were upregulated, while genes related to mammalian target of rapamycin complex 1 (mTORC1) signal pathway and lipid de novo synthesis were suppressed in HFD-BCAA restriction group compared with HFD and HFD-high BCAAs fed mice. In addition, BCAA restriction upregulated expression of BCAAs related metabolic enzymes including PPM1K and BCKDHA, and decreased the levels of BCAAs and branched chain keto acid in the pancreas. However, there was no difference in levels of lipid content in the pancreas and gene expression of AMPKα and mTORC1 between HFD and HFD-high BCAAs groups.

CONCLUSIONS

Branched-chain amino acid restriction ameliorated HFD-induced NAFPD in mice by activation of AMPKα pathway and suppression of mTORC1 pathway.

Leptin Reduction as a Required Component for Weight Loss

Partial leptin reduction can induce significant weight loss, while weight loss contributes to partial leptin reduction. The cause-and-effect relationship between leptin reduction and weight loss remains to be further elucidated. Here, we show that FGF21 and the glucagon-like peptide 1 receptor (GLP-1R) agonist liraglutide rapidly induced a reduction in leptin. This leptin reduction contributed to the beneficial effects of GLP-1R agonism in metabolic health, as transgenically maintaining leptin levels during treatment partially curtailed the beneficial effects seen with these agonists. Moreover, a higher degree of leptin reduction during treatment, induced by including a leptin neutralizing antibody with either FGF21 or liraglutide, synergistically induced greater weight loss and better glucose tolerance in diet-induced obese mice. Furthermore, upon cessation of either liraglutide or FGF21 treatment, the expected immediate weight regain was observed, associated with a rapid increase in circulating leptin levels. Prevention of this leptin surge with leptin neutralizing antibodies slowed down weight gain and preserved better glucose tolerance. Mechanistically, a significant reduction in leptin induced a higher degree of leptin sensitivity in hypothalamic neurons. Our observations support a model that postulates that a reduction of leptin levels is a necessary prerequisite for substantial weight loss, and partial leptin reduction is a viable strategy to treat obesity and its associated insulin resistance.

ARTICLE HIGHLIGHTS

Non-alcoholic fatty liver disease promotes breast cancer progression through upregulated hepatic fibroblast growth factor 21

Non-alcoholic fatty liver disease (NAFLD) has been shown to influence breast cancer progression, but the underlying mechanisms remain unclear. In this study, we investigated the impact of NAFLD on breast cancer tumor growth and cell viability through the potential mediator, hepatic fibroblast growth factor 21 (FGF21). Both peritumoral and systemic administration of FGF21 promoted breast cancer tumor growth, while FGF21 knockout attenuated the tumor-promoting effects of the high-fat diet. Mechanistically, exogenous FGF21 treatment enhanced the anti-apoptotic ability of breast cancer cells through STAT3 and Akt/FoXO1 signaling pathways, and mitigated doxorubicin-induced cell death. Furthermore, we observed overexpression of FGF21 in tumor tissues from breast cancer patients, which was associated with poor prognosis. These findings suggest a novel role for FGF21 as an upregulated mediator in the context of NAFLD, promoting breast cancer development and highlighting its potential as a therapeutic target for cancer treatment.

Phenotypic and metabolomic characteristics of mouse models of metabolic associated steatohepatitis

BACKGROUND

Metabolic associated steatohepatitis (MASH) is metabolic disease that may progress to cirrhosis and hepatocellular carcinoma. Mouse models of diet-induced MASH, which is characterized by the high levels of fats, sugars, and cholesterol in diets, are commonly used in research. However, mouse models accurately reflecting the progression of MASH in humans remain to be established. Studies have explored the potential use of serological metabolites as biomarkers of MASH severity in relation to human MASH.

METHODS

We performed a comparative analysis of three mouse models of diet-induced MASH in terms of phenotypic and metabolomic characteristics; MASH was induced using different diets: a high-fat diet; a Western diet; and a high-fat, high-cholesterol diet. Liver cirrhosis was diagnosed using standard clinical approaches (e.g., METAVIR score, hyaluronan level, and collagen deposition level). Mouse serum samples were subjected to nuclear magnetic resonance spectroscopy-based metabolomic profiling followed by bioinformatic analyses. Metabolomic analysis of a retrospective cohort of patients with hepatocellular carcinoma was performed; the corresponding cirrhosis scores were also evaluated.

RESULTS

Using clinically relevant quantitative diagnostic methods, the severity of MASH was evaluated. Regarding metabolomics, the number of lipoprotein metabolites increased with both diet and MASH progression. Notably, the levels of very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) significantly increased with fibrosis progression. During the development of diet-induced MASH in mice, the strongest upregulation of expression was noted for VLDL receptor. Metabolomic analysis of a retrospective cohort of patients with cirrhosis indicated lipoproteins (e.g., VLDL and LDL) as predominant biomarkers of cirrhosis.

CONCLUSIONS

Our findings provide insight into the pathophysiology and metabolomics of experimental MASH and its relevance to human MASH. The observed upregulation of lipoprotein expression reveals a feedforward mechanism for MASH development that may be targeted for the development of noninvasive diagnosis.

A bioactive compound digested chia protein is capable of modulating NFκB mediated hepatic inflammation in mice fed a high-fat diet

The consumption of diets high in saturated fat can induce damages in liver morphology and function, which leads to increased inflammation, oxidative stress, and hepatic steatosis. Chia seed (Salvia hispanica L.) is rich in protein, which provides bioactive peptides with potential benefits, including antioxidant and anti-inflammatory functions. Then, this study aimed to analyze the effect of digested total protein (DTP) of chia on inflammation, oxidative stress, and morphological changes in liver of C57BL/6 mice fed a diet rich in saturated fat. Male C57BL/6 mice (n = 8/group), 8 weeks old, were fed standard diet (AIN), high-fat diet (HF), standard diet added digested protein (AIN + DTP) or high-fat diet added digested protein (HF + DTP) for 8 weeks. In animals fed a high-fat diet, chia DTP was able to reduce weight gain, food efficiency ratio and hepatosomatic index. In addition, it presented antioxidant capacity, which reduced catalase activity and lipid peroxidation. DTP was also able to reduce hepatic inflammation by reducing p65-NFκB expression and IL-1β expression and quantification. The APSPPVLGPP peptide present in chia DTP presented binding capacity with PPAR-α, which contributed to the reduction of hepatic fat accumulation evidenced by histological analysis. Thus, chia DTP improved hepatic inflammatory and histological parameters, being an effective food in reducing the liver damage caused by a high-fat diet.

Didymin alleviates metabolic dysfunction-associated fatty liver disease (MAFLD) via the stimulation of Sirt1-mediated lipophagy and mitochondrial biogenesis

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) is one of the most prevalent metabolic syndromes worldwide. However, no approved pharmacological treatments are available for MAFLD. Chenpi, one kind of dried peel of citrus fruits, has traditionally been utilized as a medicinal herb for liver diseases. Didymin is a newly identified oral bioactive dietary flavonoid glycoside derived from Chenpi. In this study, we investigated the therapeutic potential of Didymin as an anti-MAFLD drug and elucidated its underlying mechanisms.

METHODS

High-fat diet (HFD)-induced MAFLD mice and alpha mouse liver 12 (AML12) cells were utilized to evaluate the effects and mechanisms of Didymin in the treatment of MAFLD. Liver weight, serum biochemical parameters, and liver morphology were examined to demonstrate the therapeutic efficacy of Didymin in MAFLD treatment. RNA-seq analysis was performed to identify potential pathways that could be affected by Didymin. The impact of Didymin on Sirt1 was corroborated through western blot, molecular docking analysis, microscale thermophoresis (MST), and deacetylase activity assay. Then, a Sirt1 inhibitor (EX-527) was utilized to confirm that Didymin alleviates MAFLD via Sirt1. Western blot and additional assays were used to investigate the underlying mechanisms.

RESULTS

Our results suggested that Didymin may possess therapeutic potential against MAFLD in vitro and in vivo. By promoting Sirt1 expression as well as directly binding to and activating Sirt1, Didymin triggers downstream pathways that enhance mitochondrial biogenesis and function while reducing apoptosis and enhancing lipophagy.

CONCLUSIONS

These suggest that Didymin could be a promising medication for MAFLD treatment. Furthermore, its therapeutic effects are mediated by Sirt1.

Effects of Fish Oil Supplementation on Reducing the Effects of Paternal Obesity and Preventing Fatty Liver in Offspring

Nonalcoholic fatty liver disease (NAFLD) is a serious public health concern, which calls for appropriate diet/nutrition intervention. Fish oil (FO) has several benefits in reducing obesity, but its intergenerational role in reducing the effects of paternal obesity has not been established. Hence, we hypothesized that FO supplementation to an obese father during the pre-conceptional period could improve the metabolic health of the offspring, specifically in the liver. Three groups of male mice were fed with a low-fat (LF), high-fat (HF), or high-fat diet supplemented with FO (HF-FO) for 10 weeks and were then allowed to mate with female mice fed a chow diet. Offspring were sacrificed at 16 weeks. The liver tissue was harvested for genomic and histological analyses. The offspring of HF and HF-FO fathers were heavier compared to that of the LF mice during 9-16 weeks. The glucose tolerance of the offspring of HF-FO fathers were significantly improved as compared to the offspring of HF fathers. Paternal FO supplementation significantly lowered inflammation and fatty acid synthesis biomarkers and increased fatty acid oxidation biomarkers in the offspring liver. In summary, FO supplementation in fathers shows the potential to reduce metabolic and cardiovascular diseases through genetic means in offspring.

A high fat, high sugar diet induces hepatic Peroxisome proliferator-activated receptor gamma coactivator 1-alpha promoter hypermethylation in male Wistar rats

Previously we reported that a high fat, high sugar (HFHS) diet induced adiposity, hyperinsulinaemia, hyperleptinaemia, hypertriglyceridaemia and increased liver mass in male Wistar rats. In the present study, the mechanisms underlying the increased liver mass were further elucidated by assessing hepatic lipid accumulation and the expression and methylation status of key metabolic genes using histology, quantitative real-time PCR and pyrosequencing, respectively. The HFHS diet induced hepatic steatosis, increased hepatic triglycerides (1.8-fold, p < 0.001), and increased the expression of sterol regulatory element-binding transcription factor 1 (Srebf1) (2.0-fold, p < 0.001) and peroxisome proliferator-activated receptor gamma (Pparg) (1.7-fold, p = 0.017) in the liver. The expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (Pgc1a) was decreased (2.6-fold, p < 0.010), which was accompanied by hypermethylation (p = 0.018) of a conserved CpG site in the promoter of Pgc1a in HFHS fed rats compared to controls. In silico analysis identified putative binding sites for CCAAT/enhancer-binding protein beta (C/EBPß) and hepatocyte nuclear factor 1 (HNF1) within proximity to the hypermethylated CpG. As Pgc1a is a co-activator of several transcription factors regulating multiple metabolic pathways, hypermethylation of this conserved CpG site in the promoter of Pgc1a may be one possible mechanism contributing to the development of hepatic steatosis in response to a HFHS diet. However, further work is required to confirm the role of Pgc1a in steatosis.

Anti-inflammatory and immunomodulating effects of rilpivirine: Relevance for the therapeutics of chronic liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease (CLD) worldwide and inflammation is key to its progression/resolution. As we have previously described that rilpivirine (RPV) is hepatoprotective in murine models of CLD, here we determine the molecular mechanisms involved, focusing on its anti-inflammatory and immunomodulating properties. They were evaluated in vitro (human hepatic cell lines of the major hepatic cell types), in vivo (liver samples from a murine nutritional model of NAFLD) and ex vivo (peripheral blood mononuclear cells -PBMC- from patients with CLD). Transcriptomic analysis of liver samples from NAFLD mice showed RPV down-regulated biological processes associated with the inflammatory response (NF-κB/IκB signaling and mitogen-activated protein kinase -MAPK- activity) and leukocyte chemotaxis and migration. We observed a decrease in Adgre1 and Ccr2 expression and in the number of CCR2 + cells in the periportal areas of RPV-treated NAFLD mice. This RPV-induced effect on the CCL2/CCR2 axis was confirmed in vitro. A similar result was also obtained with CXCL10/IP10, one of the main chemokines in the liver. RPV also diminished activation of MAP kinases p38 and JNK. In addition, RPV inhibited the NLRP3 inflammasome pathway in vitro, decreasing NLRP3 protein expression, caspase-1 activation and IL-1β gene expression. RPV was also proven anti-inflammatory in PBMC from patients with CLD treated ex vivo. In conclusion, beyond its well-described role in antiretroviral therapy, RPV manifests anti-inflammatory and immunoregulatory effects, a finding that could be of great relevance for the search of novel targets or repositioning strategies for CLD.

Alanyl-Glutamine Dipeptide Attenuates Non-Alcoholic Fatty Liver Disease Induced by a High-Fat Diet in Mice by Improving Gut Microbiota Dysbiosis

Non-alcoholic fatty liver disease (NAFLD) manifests as a persistent liver ailment marked by the excessive buildup of lipids within the hepatic organ accompanied by inflammatory responses and oxidative stress. Alanyl-glutamine (AG), a dipeptide comprising alanine and glutamine, is commonly employed as a nutritional supplement in clinical settings. This research aims to evaluate the impact of AG on NAFLD triggered by a high-fat diet (HFD), while concurrently delving into the potential mechanisms underlying its effects. The results presented herein demonstrate a notable reduction in the elevated body weight, liver mass, and liver index induced by a HFD upon AG administration. These alterations coincide with the amelioration of liver injury and the attenuation of hepatic histological advancement. Furthermore, AG treatment manifests a discernible diminution in oil-red-O-stained regions and triglyceride (TG) levels within the liver. Noteworthy alterations encompass lowered plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC) concentrations, coupled with elevated high-density lipoprotein cholesterol (HDLC) concentrations. The mitigation of hepatic lipid accumulation resultant from AG administration is aligned with the downregulation of ACC1, SCD1, PPAR-γ, and CD36 expression, in conjunction with the upregulation of FXR and SHP expression. Concomitantly, AG administration leads to a reduction in the accumulation of F4/80-positive macrophages within the liver, likely attributable to the downregulated expression of MCP-1. Furthermore, AG treatment yields a decline in hepatic MDA levels and a concurrent increase in the activities of SOD and GPX. A pivotal observation underscores the effect of AG in rectifying the imbalance of gut microbiota in HFD-fed mice. Consequently, this study sheds light on the protective attributes of AG against HFD-induced NAFLD through the modulation of gut microbiota composition.

Hypothalamic GABRA5-positive neurons control obesity via astrocytic GABA

The lateral hypothalamic area (LHA) regulates food intake and energy balance. Although LHA neurons innervate adipose tissues, the identity of neurons that regulate fat is undefined. Here we show that GABRA5-positive neurons in LHA (GABRA5LHA) polysynaptically project to brown and white adipose tissues in the periphery. GABRA5LHA are a distinct subpopulation of GABAergic neurons and show decreased pacemaker firing in diet-induced obesity mouse models in males. Chemogenetic inhibition of GABRA5LHA suppresses fat thermogenesis and increases weight gain, whereas gene silencing of GABRA5 in LHA decreases weight gain. In the diet-induced obesity mouse model, GABRA5LHA are tonically inhibited by nearby reactive astrocytes releasing GABA, which is synthesized by monoamine oxidase B (Maob). Gene silencing of astrocytic Maob in LHA facilitates fat thermogenesis and reduces weight gain significantly without affecting food intake, which is recapitulated by administration of a Maob inhibitor, KDS2010. We propose that firing of GABRA5LHA suppresses fat accumulation and selective inhibition of astrocytic GABA is a molecular target for treating obesity.

Pirfenidone ameliorates liver steatosis by targeting the STAT3-SCD1 axis

OBJECTIVE

Previous studies reported that pirfenidone (PFD) is associated with liver disease. However, the effects of pirfenidone on energy metabolism and hepatic lipid accumulation are still poorly understood.

METHODS

In this study, C57BL/6J mice were randomly divided into two groups, and fed a normal chow diet (NCD) or a high-fat diet (HFD) for 16 weeks. At the end of the eighth week, half of the mice fed on both diets were treated with PFD. Biochemical and lipid metabolism-related indices were analyzed. Furthermore, Hepa 1-6 cells and mouse primary hepatocytes (MPHs) were incubated with PFD with or without free fatty acid (FFA) treatment. Then, stattic (a p-STAT3 inhibitor) or Ad-shSTAT3 was used to further elucidate the effects of Signal Transducer and Activator of Transcription 3 (STAT3) signaling on PFD regulation of hepatic steatosis.

RESULTS

PFD ameliorated obesity and hepatic lipid deposition in HFD mice by decreasing stearoyl-CoA desaturase 1 (SCD1) expression and upregulating p-STAT3 in the liver. In Hepa 1-6 cells and MPHs, PFD also down-regulated the expression of SCD1. STAT3 inhibition treatment eliminated the benefits of PFD on both SCD1 and hepatic steatosis.

CONCLUSION

In summary, our data reveal that PFD may play an important role in mitigating hepatic steatosis in a STAT3-SCD1-dependent manner.

Gentiopicroside improves high-fat diet-induced NAFLD in association with modulation of host serum metabolome and gut microbiome in mice

Objective

The incidence of non-alcoholic fatty liver disease is increasing every year, and there is growing evidence that metabolites and intestinal bacteria play a causal role in NAFLD. Gentiopicroside, a major iridoids compound in gentian, has been reported to reduce hepatic lipid accumulation. However to date, no studies have confirmed whether the predominance of Gentiopicroside is related to metabolites and intestinal bacteria. Therefore, we sought to study whether the hypolipidemic effect of Gentiopicroside is related to metabolic function and intestinal flora regulation.

Methods

In the present study, C57BL/6J mice were fed a high-fat diet for 12 weeks, followed by a high-fat diet with or without Gentiopicroside for 8 weeks, respectively. The Gentiopicroside intervention reduced body weight gain, liver index, and decreased serum biochemical parameters such as alanine aminotransferase, aspartate aminotransferase, and triglycerides in high-fat fed mice. The effect of Gentiopicroside on non-alcoholic fatty liver disease was studied using serum untargeted metabolomics and 16S rDNA assay.

Results

Metabolomic analysis showed that the addition of Gentiopicroside significantly altered the levels of amino acids, unmetabolized Gentiopicroside after administration, and metabolites such as Cinnoline, Galabiosylceramide, and Tryptophyl-Tyrosine, which are involved in the pathways regulating bile secretion, tryptophan metabolism, and lipid metabolism. Analysis of intestinal bacteria showed that Gentiopicrosides altered the community composition structure of intestinal bacteria, characterized by an increase and a decrease in beneficial and harmful bacteria, respectively. In addition, correlation analysis showed that the effect of Gentiopicroside on metabolites was positively correlated with intestinal flora Bacteroides, Lactobacillus, Muribaculum, and Prevotellaceae_UCG_001. Finally, the combined analysis revealed that metabolites were associated with the regulation of Firmicutes and Actinobacteria and positively correlated with lipid levels.

Conclusion

These results suggest that Gentiopicroside may be a potential agent for the prevention of intestinal disorders and the alleviation of non-alcoholic fatty liver disease.

Antagonizing adipose tissue-derived exosome miR-103-hepatocyte phosphatase and tensin homolog pathway alleviates autophagy in non-alcoholic steatohepatitis: A trans-cellular crosstalk

BACKGROUND

Obesity plays a vital role in the occurrence and development of non-alcoholic steatohepatitis (NASH). However, the underlining mechanism is still unclear, where adipose tissue (AT) derived exosomes may actively participate. MicroRNAs (miRNAs) are commonly secreted from exosomes for cell communication. Though the regulation of miR-103 on insulin sensitivity has been reported, the specific role of AT-derived exosomes miR-103 in NASH is still vague and further investigation may provide novel therapeutic choices.

AIM

To determine the specific role of AT-derived exosomes miR-103 in developing NASH through various methods.

METHODS

The expression levels of miR-103 in the AT-derived exosomes and livers were detected and compared between NASH mice and control. The effect of miR-103 on NASH progression was also explored by antagonizing miR-103, including steatosis and inflammation degree changes. The interaction between miR-103 and the autophagy-related gene phosphatase and tensin homolog (PTEN) was confirmed by dual-luciferase reporter assay. The role of the interaction between miR-103 and PTEN on autophagy was verified in NASH-like cells. Finally, the effects of miR-103 from adipose-derived exosomes on NASH and autophagy were analyzed through animal experiments.

RESULTS

The expression of miR-103 was increased in NASH mice, compared to the control, and inhibition of miR-103 could alleviate NASH. The results of the dual-luciferase reporter assay showed miR-103 could interact with PTEN. MiR-103-anta decreased p-AMPKa, p-mammalian target of rapamycin (mTOR), and p62 but increased the protein levels of PTEN and LC3-II/I and the number of autophagosomes in NASH mice. Similar results were also observed in NASH-like cells, and further experiments showed PTEN silencing inhibited the effect of miR-103-anta. AT derived-exosome miR-103 aggravated NASH and increased the expressions of p-AMPKa, p-mTOR, and p62 but decreased the protein levels of PTEN and LC3-II/I and the number of autophagosomes in mice.

CONCLUSION

AT derived-exosome increased the levels of miR-103 in the liver, and miR-103 aggravated NASH. Mechanically, miR-103 could interact with PTEN and inhibit autophagy.

Loss of hepatic PPARα in mice causes hypertension and cardiovascular disease

The leading cause of death in patients with nonalcoholic fatty liver disease (NAFLD) is cardiovascular disease (CVD). However, the mechanisms are unknown. Mice deficient in hepatocyte proliferator-activated receptor-α (PPARα) (PparaHepKO) exhibit hepatic steatosis on a regular chow diet, making them prone to manifesting NAFLD. We hypothesized that the PparaHepKO mice might be predisposed to poorer cardiovascular phenotypes due to increased liver fat content. Therefore, we used PparaHepKO and littermate control mice fed a regular chow diet to avoid complications with a high-fat diet, such as insulin resistance and increased adiposity. After 30 wk on a standard diet, male PparaHepKO mice exhibited elevated hepatic fat content compared with littermates as measured by Echo MRI (11.95 ± 1.4 vs. 3.74 ± 1.4%, P < 0.05), hepatic triglycerides (1.4 ± 0.10 vs. 0.3 ± 0.01 mM, P < 0.05), and Oil Red O staining, despite body weight, fasting blood glucose, and insulin levels being the same as controls. The PparaHepKO mice also displayed elevated mean arterial blood pressure (121 ± 4 vs. 108 ± 2 mmHg, P < 0.05), impaired diastolic function, cardiac remodeling, and enhanced vascular stiffness. To determine mechanisms controlling the increase in stiffness in the aorta, we used state-of-the-art PamGene technology to measure kinase activity in this tissue. Our data suggest that the loss of hepatic PPARα induces alterations in the aortas that reduce the kinase activity of tropomyosin receptor kinases and p70S6K kinase, which might contribute to the pathogenesis of NAFLD-induced CVD. These data indicate that hepatic PPARα protects the cardiovascular system through some as-of-yet undefined mechanism.

Effects of miR-33 Deficiency on Metabolic and Cardiovascular Diseases: Implications for Therapeutic Intervention

MicroRNAs (miRNAs) are small noncoding RNAs that post-transcriptionally inhibit gene expression. These small molecules are involved in several biological conditions such as inflammation, cell growth and proliferation, and regulation of energy metabolism. In the context of metabolic and cardiovascular diseases, miR-33 is of particular interest as it has been implicated in the regulation of lipid and glucose metabolism. This miRNA is located in introns harboured in the genes encoding sterol regulatory element-binding protein (SREBP)-1 and SREBP-2, which are key transcription factors involved in lipid biosynthesis and cholesterol efflux. This review outlines the role of miR-33 in a range of metabolic and cardiovascular pathologies, such as dyslipidaemia, nonalcoholic fatty liver disease (NAFLD), obesity, diabetes, atherosclerosis, and abdominal aortic aneurysm (AAA), and it provides discussion about the effectiveness of miR-33 deficiency as a possible therapeutic strategy to prevent the development of these diseases.

Pyridylnidulin exerts anti-diabetic properties and improves non-alcoholic fatty liver disease in diet-induced obesity mice

Introduction: Non-alcoholic fatty liver disease (NAFLD) is one of the metabolic disorders related to the pathophysiology of type 2 diabetes mellitus (T2DM). Therapeutic strategies are focused on the improvement of energy balance and lifestyle modification. Additionally, the derivative of the bioactive fungal metabolite is of interest to provide health benefits, especially in obese and pre-diabetic conditions. In our screening of anti-diabetic compounds from fungal metabolites and semisynthetic derivatives, a depsidone derivative, namely pyridylnidulin (PN), showed potent glucose uptake-inducing activity. The present study aimed to investigate the liver lipid metabolism and anti-diabetic properties of PN in diet-induced obesity mice. Methods: Male C57BL/6 mice were induced obesity and pre-diabetic conditions by dietary intervention with a high-fat diet (HFD) for 6 weeks. These obese mice were orally administered with PN (40 or 120 mg/kg), metformin (150 mg/kg), or vehicle for 4 weeks. Glucose tolerance, plasma adipocytokines, hepatic gene and protein expressions were assessed after treatment. Results: Improved glucose tolerance and reduced fasting blood glucose levels were found in the PN and metformin-treated mice. Additionally, hepatic triglyceride levels were consistent with the histopathological steatosis score regarding hepatocellular hypertrophy in the PN and metformin groups. The levels of plasma adipocytokines such as tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) were reduced in the PN (120 mg/kg) and metformin-treated mice. In addition, hepatic gene expression involved in lipid metabolism, including lipogenic enzymes was significantly reduced in the PN (120 mg/kg) and metformin-treated mice. The increased protein expression levels of phosphorylated AMP-activated protein kinase (p-AMPK) was also found in PN and metformin-treated mice. Discussion: Considering the increased p-AMPK protein expression levels in PN and metformin-treated mice were revealed as the underlying mechanisms to improve metabolic parameters. These results suggested that PN provided the health benefit to slow the progression of NAFLD and T2DM in obese and pre-diabetic conditions.

Proteomic and Global DNA Methylation Modulation in Lipid Metabolism Disorders with a Marine-Derived Bioproduct

Dyslipidemia is a significant risk factor for cardiovascular disease and stroke. Our recent findings showed that RCI-1502, a bioproduct derived from the muscle of the European S. pilchardus, has lipid-lowering effects in the liver and heart in high-fat diet (HFD) fed mice. In the present follow-up study, we investigated the therapeutic potential of RCI-1502 on gene expression and DNA methylation in HFD-fed mice and in patients with dyslipidemia. Using LC-MS/MS, we identified 75 proteins in RCI-1502 that are primarily involved in binding and catalytic activity and which regulate pathways implicated in cardiovascular diseases. In HFD-fed mice, RCI-1502 treatment significantly reduced the expression of cardiovascular disease-related genes, including vascular cell adhesion molecule and angiotensin. RCI-1502 also decreased DNA methylation levels, which were elevated in HFD-fed mice, to levels similar to those in control animals. Furthermore, peripheral blood leukocyte DNA from dyslipidemic patients exhibited higher DNA methylation levels than healthy individuals, suggesting a potential association with cardiovascular risk. Serum analysis also revealed that RCI-1502 treatment regulated cholesterol and triglyceride levels in patients with dyslipidemia. Our findings appear to suggest that RCI-1502 is an epigenetic modulator for the treatment of cardiovascular diseases, specifically in individuals with dyslipidemia.

Umbelliferone Ameliorates Hepatic Steatosis and Lipid-Induced ER Stress in High-Fat Diet-Induced Obese Mice

PURPOSE

Among the characteristics of non-alcoholic fatty liver disease (NAFLD), hepatic steatosis is due to excessive fat accumulation and causes liver damage and lipotoxicity, which are associated with insulin resistance, endoplasmic reticulum (ER) stress, and apoptosis. Umbelliferone (UMB) has various powerful pharmacological properties, such as antioxidant, anti-hyperglycemic, anti-viral, and anti-inflammatory effects. However, the mechanism of action in hepatic steatosis and lipid-induced ER stress is still unclear. Thus, the efficacy of UMB in hepatic steatosis and palmitate (PA)-induced hepatocellular lipotoxicity was evaluated in the present study.

MATERIALS AND METHODS

Male C57BL/6J mice (n=40) were divided into four groups: regular diet (RD), UMB-supplemented RD, high-fat diet (HFD), and UMB-supplemented HFD. All mice were fed orally for 12 weeks. In addition, the effects of UMB on lipotoxicity were investigated in AML12 cells treated with PA (250 µM) for 24 h; Western blot analysis was used to evaluate the changes in ER stress and apoptotic-associated proteins.

RESULTS

Administration with UMB in HFD-fed mice reduced lipid accumulation and hepatic triglyceride (TG) as well as serum insulin and glucose levels. In AML12 cells, UMB treatment reduced lipid accumulation as indicated by decreases in the levels of lipogenesis markers, such as SREBP1, FAS, PPAR-γ, and ADRP. Furthermore, UMB reduced both oxidative stress and ER stress-related cellular apoptosis.

CONCLUSION

UMB supplementation ameliorated hepatic steatosis and improved insulin resistance by inhibiting lipid accumulation and regulating ER stress. These findings strongly suggest that UMB may be a potential therapeutic compound against NAFLD.

Short-Term Growth Hormone Administration Mediates Hepatic Fatty Acid Uptake and De Novo Lipogenesis Gene Expression in Obese Rats

Obesity has been linked to metabolic syndrome, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD). Obesity causes a decrease in growth hormone (GH) levels and an increase in insulin levels. Long-term GH treatment increased lipolytic activity as opposed to decreasing insulin sensitivity. Nonetheless, it is possible that short-term GH administration had no impact on insulin sensitivity. In this study, the effect of short-term GH administration on liver lipid metabolism and the effector molecules of GH and insulin receptors were investigated in diet-induced obesity (DIO) rats. Recombinant human GH (1 mg/kg) was then administered for 3 days. Livers were collected to determine the hepatic mRNA expression and protein levels involved in lipid metabolism. The expression of GH and insulin receptor effector proteins was investigated. In DIO rats, short-term GH administration significantly reduced hepatic fatty acid synthase (FASN) and cluster of differentiation 36 (CD36) mRNA expression while increasing carnitine palmitoyltransferase 1A (CPT1A) mRNA expression. Short-term GH administration reduced hepatic FAS protein levels and downregulated gene transcription of hepatic fatty acid uptake and lipogenesis, while increasing fatty acid oxidation in DIO rats. DIO rats had lower hepatic JAK2 protein levels but higher IRS-1 levels than control rats due to hyperinsulinemia. Our findings suggest that short-term GH supplementation improves liver lipid metabolism and may slow the progression of NAFLD, where GH acts as the transcriptional regulator of related genes.

Innate-like T lymphocytes in chronic liver disease

In addition to its metabolic activities, it is now clear that the liver hosts a number of diverse immune cell types that control tissue homeostasis. Foremost among these are innate-like T lymphocytes, including natural killer T (NKT) and mucosal-associated innate T (MAIT) cells, which are a population of specialized T cells with innate characteristics that express semi-invariant T cell receptors with non-peptide antigen specificity. As primary liver residents, innate-like T cells have been associated with immune tolerance in the liver, but also with a number of hepatic diseases. Here, we focus on the biology of NKT and MAIT cells and how they operate during the course of chronic inflammatory diseases that eventually lead to hepatocellular carcinoma.

New insights into the role of dietary triglyceride absorption in obesity and metabolic diseases

The incidence of obesity and associated metabolic diseases is increasing globally, adversely affecting human health. Dietary fats, especially triglycerides, are an important source of energy for the body, and the intestine absorbs lipids through a series of orderly and complex steps. A long-term high-fat diet leads to intestinal dysfunction, inducing obesity and metabolic disorders. Therefore, regulating dietary triglycerides absorption is a promising therapeutic strategy. In this review, we will discuss diverse aspects of the dietary triglycerides hydrolysis, fatty acid uptake, triglycerides resynthesis, chylomicron assembly, trafficking, and secretion processes in intestinal epithelial cells, as well as potential targets in this process that may influence dietary fat-induced obesity and metabolic diseases. We also mention the possible shortcomings and deficiencies in modulating dietary lipid absorption targets to provide a better understanding of their administrability as drugs in obesity and related metabolic disorders.

High fat diet is protective against kidney injury in hypertensive-diabetic mice, but leads to liver injury

Chronic kidney disease (CKD) is a worldwide health burden with increases risk of end-stage renal function if left untreated. CKD induced in the context of metabolic syndrome (MS) increases risks of hypertension, hyperglycemia, excess body fat and dyslipidemia. To test if combining a high-fat diet (HFD) regimen onto the hypertensive/ diabetic phenotype would mimic features of MS induced-CKD in mice, hyperglycemia was induced in genetically hypertensive mice (Lin), followed by HFD regimen. For that, 8-week-old male were subjected to streptozotocin (STZ) intraperitoneal (i.p.) injections (50 mg/kg, 5 days consecutive). LinSTZ were fed a 60% kCal HFD for 8 weeks. Lin mice treated with STZ developed polydipsia, became hypertensive and hyperglycemic. HFD induced weight gain, protected against glomerular hypertrophy, scarring, and albuminuria at endpoint compared to regular diet fed LinSTZ. On the other hand, HFD induced steatosis, liver fibrosis, inflammation, and increase in AST/ALT ratio, characteristics of non-alcoholic liver disease. Taken together, our results show that LinSTZ mice fed a HFD did not lead to a more robust model of MS-induced CKD, protected against kidney injury, but inducing liver damage. More studies are necessary to understand the kidney protective mechanisms of HFD when superimposed with hypertension and type 1 diabetes.

Association Between Protein Intake From Different Animal and Plant Origins and the Risk of Non-Alcoholic Fatty Liver Disease: A Case-Control Study

Previous studies have frequently reviewed how different macronutrients affect liver health. Still, no study centered around protein intake and the non-alcoholic fatty liver disease (NAFLD) risk relationship. This study aimed to examine the association between the consumption of total and different sources of protein and NAFLD risk. We allocated 243 eligible subjects to the case and control groups, including 121 incidence cases of NAFLD, and 122 healthy controls. Two groups were matched in age, body mass index, and sex. We evaluated the usual food intake of participants using FFQ. Binary logistic regression was conducted to estimate the risk of NAFLD in relation to different sources of protein intake. The age of participants was 42.7 years on average, and 53.1% were male. We found Higher intake of protein in total (odds ratio [OR], 0.24; 95% confidence interval [CI], 0.11-0.52) was significantly associated with a lower risk of NAFLD, despite adjusting for multiple confounders. in detail, higher tendency to the vegetables (OR, 0.28; 95% CI, 0.13-0.59), grains (OR, 0.24; 95% CI, 0.11-0.52), and nuts (OR, 0.25; 95% CI, 0.12-0.52) as the main sources of protein, were remarkably correlated with lower NAFLD risk. In contrary, increased intake of meat protein (OR, 3.15; 95% CI, 1.46-6.81) was positively associated with a higher risk. Totally, more calorie intake from proteins was inversely associated with lower NAFLD risk. This was more likely when the protein sources were selected less from meats and more from plants. Accordingly, increasing the consumption of proteins, particularly from plants, may be a good recommendation to manage and prevent NAFLD.

Fecal Protein Analysis of Dusp6 Knockout C57BL/6J Mice by Metaproteomics

The research of obesity and gut microbiota has been carried out for years, yet the study process was in a slow pace for several challenges to conquer. As a complex status of disorder, the contributing factors refer to gut microbiota about obesity were controversial in a wide range. In terms of proteomics, 2D-DIGE technology is a powerful method for this study to identify fecal proteins from lean microbiota in Dusp6 knockout C57BL/6J mice, exploring the protein markers of the ability resisting to diet-induced obesity (DIO) transferred to the host mice after fecal microbiota transplantation. The results showed that the fecal microbiota expressed 289 proteins differentially with 23 proteins identified, which were considered to be the reasons to assist the microbiota exhibiting distinct behavior. By means of proteomics technology, we had found that differentially expressed proteins of lean microbiota determined the lean microbial behavior might be able to resist leaky gut. To sum up our study, the proteomics strategies offered as a tool to demonstrate and analyze the features of lean microbiota, providing new speculations in the behavior about the gut microbiota reacting to DIO.

Cardiovascular and lipid-lowering effects of a marine lipoprotein extract in a high-fat diet-induced obesity mouse model

Obesity is a major health challenge worldwide, with implications for diabetes, hypertension and cardiovascular disease (CVD). Regular consumption of dark-meat fish is linked to a lower incidence of CVD and associated metabolic disorders due to the presence of long-chain omega-3 fatty acid ethyl esters in fish oils. The aim of the present study was to determine whether a marine compound like a sardine lipoprotein extract (RCI-1502), regulates fat accumulation in the heart of a high-fat diet-induced (HFD) mouse model of obesity. To investigate its effects in the heart and liver, we conducted a randomized, 12-week placebo-controlled study in which we analyzed the expression of vascular inflammation markers, obesity biochemical patterns and related CVD pathologies. Male HFD-fed mice treated with a RCI-1502-supplemented diet showed reduced body weight, abdominal fat tissue and pericardial fat pad mass density without systemic toxicity. RCI-1502 significantly reduced triacylglyceride, low-density lipoprotein and total-cholesterol concentrations in serum, but increased HDL-cholesterol levels. Our data show that RCI-1502 is beneficial for reducing obesity associated with a long-term HFD, possibly by exerting a protective effect on lipidic homeostasis, indicated also by histopathological analysis. These results collectively indicate that RCI-1502 acts as a cardiovascular therapeutic nutraceutical agent, which modulates fat-induced inflammation and improves metabolic health.

Antiobesity Effect of Lacticaseibacillus paracasei LM-141 on High-Fat Diet-Induced Rats through Alleviation of Inflammation and Insulin Resistance

In this study, we set out to evaluate the antiobesity activities of our newly isolated Lacticaseibacillus paracasei LM-141 (LPLM141) using a high-fat diet (HFD)-fed rat model. Male Sprague-Dawley rats were fed with a HFD with or without low-dosage (2 × 10⁷ CFU/day per rat) or high-dosage (2 × 10⁹ CFU/day per rat) LPLM141 for 14 weeks. The results showed that administration of LPLM141 significantly decreased body weight gain, liver weight, adipose tissue weight, and epididymal white adipocyte size increased by HFD feeding. The abnormal serum lipid profile induced by HFD feeding was normalized by administration of LPLM141. The enhanced chronic low-grade inflammation in HFD-fed rats was reduced by LPLM141 supplementation, as reflected by decreased serum lipopolysaccharide (LPS) and monocyte chemoattractant protein-1 (MCP-1) levels, reduced macrophage infiltration in adipose tissue, and increased serum adiponectin concentration. In addition, the elevations of proinflammatory cytokine genes and suppression of PPAR-γ mRNA in adipose tissues of rats fed with a HFD were markedly reversed by LPLM141 administration. Oral administration of LPLM141 induced browning of epididymal white adipose tissue (eWAT) and activation of interscapular brown adipose tissue (iBAT) in rats fed with HFD. Consumption of LPLM141 exhibited a significant amelioration in insulin resistance, which were mechanistically caused by downregulation of the serum leptin level and upregulation of hepatic IRS-1 and p-Akt protein expressions, in HFD treated rats. LPLM141 consumption significantly decreased hepatic lipogenic gene expressions and preserved liver function stimulated by HFD treatment. Administration of LPLM141 obviously mitigated hepatic steatosis observed in HFD feeding rats. Our current findings shed light on LPLM141 supplementation that exhibited an antiobesity effect in HFD-fed rats by alleviating inflammation and insulin resistance, which further highlighted the potential of utilizing LPLM141 as a preventive/therapeutic probiotic agent for obesity.

The Synergistic Protective Effect of γ-Oryzanol (OZ) and N-Acetylcysteine (NAC) against Experimentally Induced NAFLD in Rats Entails Hypoglycemic, Antioxidant, and PPARα Stimulatory Effects

This study estimated that the combined effect of γ-Oryzanol and N-acetylcysteine (NAC) against high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) in rats also estimated some of their mechanisms of action. Adult male rats were divided into seven groups (n = 8 each) as control, control + NAC, control + γ-Oryzanol, HFD, HFD + NAC, HFD + γ-Oryzanol, and HFD + NAC + γ-Oryzanol. NAC was administered orally at a final concentration of 200 mg/kg, whereas γ-Oryzanol was added to diets at a concentration of 0.16. All treatments were conducted for 17 weeks and daily. Both NAC and γ-Oryzanol were able to reduce final body weights, fat weights, fasting glucose, fasting insulin, serum, and serum levels of liver function enzymes as well as the inflammatory markers such as tumor necrosis factor-α (TNF-α), interleukine-6 (IL-6), and leptin in HFD-fed rats. They also improved hepatic structure and glucose tolerance, increased adiponectin levels, and reduced serum and hepatic levels of triglycerides (TGs) and cholesterol (CHOL) in these rats. These effects were concomitant with a reduction in the hepatic levels of lipid peroxides (MDA) and serum levels of LDL-C, but also with an increment in the hepatic levels of superoxide dismutase (SOD) and glutathione (GSH). Interestingly, only treatment with γ-Oryzanol stimulated the mRNA levels of proliferator-activated receptor alpha (PPARα) and carnitine palmitoyltransferase 1 (CPT1) in the liver and white adipose tissue (WAT) of rats. Of note, the combination therapy of both drugs resulted in maximum effects and restored almost normal liver structure and basal levels of all the above-mentioned metabolic parameters. In conclusion, a combination therapy of γ-Oryzanol and NAC is an effective therapy to treat NAFLD, which can act via several mechanisms on the liver and adipose tissue.

Identification of a Chromosome 1 Substitution Line B6-Chr1BLD as a Novel Hyperlipidemia Model via Phenotyping Screening

Hyperlipidemia is a chronic disease that seriously affects human health. Due to the fact that traditional animal models cannot fully mimic hyperlipidemia in humans, new animal models are urgently needed for basic drug research on hyperlipidemia. Previous studies have demonstrated that the genomic diversity of the wild mice chromosome 1 substitution lines was significantly different from that of laboratory mice, suggesting that it might be accompanied by phenotypic diversity. We first screened the blood lipid-related phenotype of chromosome 1 substitution lines. We found that the male HFD-fed B6-Chr1BLD mice showed more severe hyperlipidemia-related phenotypes in body weight, lipid metabolism and liver lesions. By RNA sequencing and whole-genome sequencing results of B6-Chr1BLD, we found that several differentially expressed single nucleotide polymorphism enriched genes were associated with lipid metabolism-related pathways. Lipid metabolism-related genes, mainly including Aida, Soat1, Scly and Ildr2, might play an initial and upstream role in the abnormal metabolic phenotype of male B6-Chr1BLD mice. Taken together, male B6-Chr1BLD mice could serve as a novel, polygenic interaction-based hyperlipidemia model. This study could provide a novel animal model for accurate clinical diagnosis and precise medicine of hyperlipidemia.

Ketogenic Diet Increases Serum and White Adipose Tissue SIRT1 Expression in Mice

Overnutrition and its sequelae have become a global concern due to the increasing incidence of obesity and insulin resistance. A ketogenic diet (KD) is widely used as a dietary treatment for metabolic disorders. Sirtuin1 (SIRT1), a metabolic sensor which regulates fat homeostasis, is modulated by dietary interventions. However, the influence of nutritional ketosis on SIRT1 is still debated. We examined the effect of KD on adipose tissue, liver, and serum levels of SIRT1 in mice. Adult C57BL/6J male mice were randomly assigned to two isocaloric dietary groups and fed with either high-fat KD or normal chow (NC) for 4 weeks. Serum SIRT1, beta-hydroxybutyrate (βHB), glucose, and triglyceride levels, as well as SIRT1 expression in visceral (VAT), subcutaneous (SAT), and brown (BAT) adipose tissues, and in the liver, were measured. KD-fed mice showed an increase in serum βHB in parallel with serum SIRT1 (r = 0.732, p = 0.0156), and increased SIRT1 protein expression in SAT and VAT. SIRT1 levels remained unchanged in BAT and in the liver, which developed steatosis. Normal glycemia and triglycerides were observed. Under a KD, serum and white fat phenotypes show higher SIRT1, suggesting that one of the molecular mechanisms underlying a KD's potential benefits on metabolic health involves a synergistic interaction with SIRT1.

Ferulic Acid and P-Coumaric Acid Synergistically Attenuate Non-Alcoholic Fatty Liver Disease through HDAC1/PPARG-Mediated Free Fatty Acid Uptake

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease and has become a growing public health concern worldwide. Polyphenols may improve high-fat diet (HFD)-related NAFLD. Our previous study found that ferulic acid (FA) and p-coumaric acid (p-CA) were the polyphenols with the highest content in foxtail millet. In this study, we investigated the mechanism underlying the impact of ferulic acid and p-coumaric acid (FA/p-CA) on non-alcoholic fatty liver (NAFLD). The association of FA and p-CA with fatty liver was first analyzed by network pharmacology. Synergistic ameliorating of NAFLD by FA and p-CA was verified in oleic acid (OA) and palmitic acid (PA) (FFA)-treated hepatocytes. Meanwhile, FA/p-CA suppressed final body weight and TG content and improved liver dysfunction in HFD-induced NAFLD mice. Mechanistically, our data indicated that FA and p-CA bind to histone deacetylase 1 (HDAC1) to inhibit its expression. The results showed that peroxisome proliferator activated receptor gamma (PPARG), which is positively related to HDAC1, was inhibited by FA/p-CA, and further suppressed fatty acid binding protein (FABP) and fatty acid translocase (CD36). It suggests that FA/p-CA ameliorate NAFLD by inhibiting free fatty acid uptake via the HDAC1/PPARG axis, which may provide potential dietary supplements and drugs for prevention of NAFLD.

Moderate Treadmill Exercise Alleviates NAFLD by Regulating the Biogenesis and Autophagy of Lipid Droplet

Lipid droplet is a dynamic organelle that undergoes periods of biogenesis and degradation under environmental stimuli. The excessive accumulation of lipid droplets is the major characteristic of non-alcoholic fatty liver disease (NAFLD). Moderate aerobic exercise is a powerful intervention protecting against the progress of NAFLD. However, its impact on lipid droplet dynamics remains ambiguous. Mice were fed with 15 weeks of high-fat diet in order to induce NAFLD. Meanwhile, the mice performed 15 weeks of treadmill exercise. Our results showed that 15 weeks of regular moderate treadmill exercise alleviated obesity, insulin intolerance, hyperlipidemia, and hyperglycemia induced by HFD. Importantly, exercise improved histological phenotypes of NAFLD, including hepatic steatosis, inflammation, and locular ballooning, as well as prevented liver fat deposition and liver injury induced by HFD. Exercise reduced hepatic lipid droplet size, and moreover, it reduced PLIN2 protein level and increased PLIN3 protein level in the liver of HFD mice. Interestingly, our results showed that exercise did not significantly affect the gene expressions of DGAT1, DGAT2, or SEIPIN, which were involved in TG synthesis. However, it did reduce the expressions of FITM2, CIDEA, and FSP27, which were major involved in lipid droplet growth and budding, and lipid droplet expansion. In addition, exercise reduced ATGL protein level in HFD mice, and regulated lipophagy-related markers, including increasing ATG5, LAMP1, LAMP2, LAL, and CTSD, decreasing LC3II/I and p62, and promoting colocalization of LAMP1 with LDs. In summary, our data suggested that 15 weeks of moderate treadmill exercise was beneficial for regulating liver lipid droplet dynamics in HFD mice by inhibiting abnormal lipid droplets expansion and enhancing clearance of lipid droplets by lysosomes during the lipophagic process, which might provide highly flexible turnover for lipid mobilization and metabolism. Abbreviations: β-actin: actin beta; ATG5: autophagy related 5; LAMP2: lysosomal-associated membrane protein 2; LAMP1: lysosomal-associated membrane protein 1; SQSTM1/p62: sequestosome 1; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; ATGL: adipose triglyceride lipase; CSTD: cathepsin D; LAL: lysosomal acid lipase; DGAT1: diacylglycerol-o-acyltransferase 1; DGAT2: diacylglycerol-o-acyltransferase 2; CIDEA: cell death inducing dffa-like effector a; CIDEC/FSP27: cell death inducing dffa-like effector c; FITM2: fat storage-inducing transmembrane protein 2; PLIN2: adipose differentiation related protein; PLN3: tail-interacting protein 47; HSP90: heat shock protein 90; SREBP1c: sterol regulatory element binding protein-1c; chREBP: carbohydrate response element binding protein.

Shedding light on non-alcoholic fatty liver disease: Pathogenesis, molecular mechanisms, models, and emerging therapeutics

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder globally impacting an estimated 25% of the population associated with severe consequences such as cirrhosis, hepatocellular carcinoma (HCC), and overall mortality. Fatty liver disease is triggered through multiple pathways, but the most prominent cause is either diabetes or obesity, or a combination of both. Therefore, hepatic glucose, insulin and fatty acid signaling becomes a dire need to understand which is well elaborated in this review. This review summarizes the popular two-hit pathogenesis of NAFLD, the molecular mechanisms underlying hepatic insulin resistance. As fatty liver disease gets advanced, it requires in-vitro as well as in-vivo models closer to disease progression in humans for better understanding the pathological state and identifying a novel therapeutic target. This review summarizes in-vitro (2D cell-culture/co-culture, 3D spheroid/organoid/liver-on-a-chip) models as well as in-vivo (genetically/dietary/chemically induced fatty liver disease) research models. Fatty liver disease research has gathered lots of attention recently since there is no FDA approved therapy available so far. However, there have been numerous promising targets to treat fatty liver disease including potential therapeutic targets under clinical trials are listed in this review.

Oral Administration of Recombinant Lactoferrin-Expressing Probiotics Ameliorates Diet-Induced Lipid Accumulation and Inflammation in Non-Alcoholic Fatty Liver Disease in Mice

We have recently developed probiotics that can express bovine, human, or porcine lactoferrin (LF), and the present study evaluated the effect of these probiotics in improving non-alcoholic fatty liver disease (NAFLD). Three kinds of probiotic supplements, including lactic acid bacteria (LAB), LAB/LF, and inactivated LAB/LF, were prepared. The LAB supplement was prepared from 10 viable LAB without recombinant LF-expression, the LAB/LF supplement was prepared from 10 viable probiotics expressing LF, and the inactivated LAB/LF supplement was prepared from 10 inactivated probiotics expressing LF. A model of obese/NAFLD mice induced by a high-fat diet was established, and the mice were randomly divided into four groups and fed with a placebo, LAB, LAB/LF, or inactivated LAB daily for four weeks via oral gavage. The body weight, food intake, organ weight, biochemistry, and hepatic histopathological alterations and severity scoring were measured. The results revealed that the obese mice fed with any one of the three probiotic mixtures prepared from recombinant probiotics for four weeks exhibited considerably improved hepatic steatosis. These findings confirmed the assumption that specific probiotic strains or LF supplements could help to control NAFLD, as suggested in previous reports. Our data also suggest that the probiotics and LFs in probiotic mixtures contribute differently to improving the efficacy against NAFLD, and the expressed LF content in probiotics may help to boost their efficacy in comparison with the original probiotic mixtures. Moreover, when these LF-expressing probiotics were further inactivated by sonication, they displayed better efficacies than the viable probiotics against NAFLD. This study has provided intriguing data supporting the potential of recombinant probiotics in improving hepatic steatosis.

Postbiotics Prepared Using Lactobacillus paracasei CCFM1224 Prevent Nonalcoholic Fatty Liver Disease by Modulating the Gut Microbiota and Liver Metabolism

Postbiotics are rich in a variety of bioactive components, which may have beneficial effects in inhibiting hepatic lipid accumulation. In this study, we investigated the preventive effects of postbiotics (POST) prepared from Lactobacillus paracasei on non-alcoholic fatty liver disease (NAFLD). Our results showed that when mice ingested a high-fat diet (HFD) and POST simultaneously, weight gain was slowed, epididymal white fat hypertrophy and insulin resistance were suppressed, serum biochemical indicators related to blood lipid metabolism were improved, and hepatic steatosis and liver inflammation decreased. Bacterial sequencing showed that POST modulated the gut microbiota in HFD mice, increasing the relative abundance of Akkermansia and reducing the relative abundance of Lachnospiraceae NK4A136 group, Ruminiclostridium and Bilophila. Spearman’s correlation analysis revealed significant correlations between lipid metabolism parameters and gut microbes. Functional prediction results showed that the regulation of gut microbiota was associated with the improvement of metabolic status. The metabolomic analysis of the liver revealed that POST-regulated liver metabolic pathways, such as glycerophospholipid and ether lipid metabolism, pantothenate and CoA biosynthesis, some parts of amino acid metabolism, and other metabolic pathways. In addition, POST regulated the gene expression in hepatocytes at the mRNA level, thereby regulating lipid metabolism. These findings suggest that POST plays a protective role against NAFLD and may exert its efficacy by modulating the gut microbiota and liver metabolism, and these findings may be applied to related functional foods.

Emerging degrader technologies engaging lysosomal pathways

Targeted protein degradation (TPD) provides unprecedented opportunities for drug discovery. While the proteolysis-targeting chimera (PROTAC) technology has already entered clinical trials and changed the landscape of small-molecule drugs, new degrader technologies harnessing alternative degradation machineries, especially lysosomal pathways, have emerged and broadened the spectrum of degradable targets. We have recently proposed the concept of autophagy-tethering compounds (ATTECs) that hijack the autophagy protein microtubule-associated protein 1A/1B light chain 3 (LC3) for targeted degradation. Other groups also reported degrader technologies engaging lysosomal pathways through different mechanisms including AUTACs, AUTOTACs, LYTACs and MoDE-As. In this review, we analyse and discuss ATTECs along with other lysosomal-relevant degrader technologies. Finally, we will briefly summarize the current status of these degrader technologies and envision possible future studies.

Combined exposure to PM2.5 and high-fat diet facilitates the hepatic lipid metabolism disorders via ROS/miR-155/PPARγ pathway

Environmental fine particulate matter (PM_2.5), which has attracted worldwide attention, is associated with the progression of metabolic-associated fatty liver disease (MAFLD). However, it is unclear whether dietary habit exacerbate liver damage caused by PM_2.5. The current study aimed to investigate the combined negative effects of PM_2.5 and high-fat diet (HFD) on liver lipid metabolism in C57BL/6J mice. Histopathological and Oil-Red O staining analysis illustrated that PM_2.5 exposure resulted in increased liver fat content in HFD-fed C57BL/6J mice, but not in standard chow diet (STD)-fed mice. And there was a synergistic effect between PM_2.5 and HFD on hepatic lipotoxicity. The increased ROS levels and augmented oxidative damage were evaluated in liver tissue of mice treated with PM_2.5 and HFD together. In addition, excessive ROS production could activate the miR-155/peroxisome proliferator-activated receptor gamma (PPARγ) pathway, including up-regulation of lipid accumulation-related protein expressions of recombinant liver X receptor alpha (LXRα), sterol regulatory element binding protein-1 (SREBP-1), stearoyl-CoA desaturase-1 (SCD1), fatty acid synthase (FAS) and acetyl-CoA carboxylase 1 (ACC1).The use of miR-155 inhibitors demonstrated the indispensable role of miR-155 in the activation of lipid-regulated proteins by PM_2.5 and palmitic acid (PA). Collectively, altering high-fat dietary habits could protect against MAFLD motivated by air pollution, and miR-155 might be an effective preventive and therapeutic target for this process.

Long Noncoding RNAs That Function in Nutrition: Lnc-ing Nutritional Cues to Metabolic Pathways

Long noncoding RNAs (lncRNAs) are sensitive to changing environments and play key roles in health and disease. Emerging evidence indicates that lncRNAs regulate gene expression to shape metabolic processes in response to changing nutritional cues. Here we review various lncRNAs sensitive to fasting, feeding, and high-fat diet in key metabolic tissues (liver, adipose, and muscle), highlighting regulatory mechanisms that trigger expression changes of lncRNAs themselves, and how these lncRNAs regulate gene expression of key metabolic genes in specific cell types or across tissues. Determining how lncRNAs respond to changes in nutrition is critical for our understanding of the complex downstream cascades following dietary changes and can shape how we treat metabolic disease. Furthermore, investigating sex biases that might influence lncRNA-regulated responses will likely reveal contributions toward the observed disparities between the sexes in metabolic diseases.

Tyrosol Ameliorates Liver Inflammatory Response in a Mouse Model of Nonalcoholic Fatty Liver Disease (NFALD) by Regulating JAK1/STAT3

Nonalcoholic fatty liver disease (NAFLD) is becoming one of the major health issues globally. NAFLD is usually associated with obesity and other metabolic syndromes, and there is no specific cure to address this issue so far. Featured by lipid accumulation in hepatocytes, and later progressing to fibrosis, inflammatory responses are involved in the various levels of the pathological changes. In the present study, we added a natural compound, tyrosol, which in our previous study had demonstrated anti-inflammatory properties, to a high-fat diet-induced NAFLD mouse model and investigated whether tyrosol could mitigate the liver damage by attenuating the inflammation response. The treatment with tyrosol significantly improved the liver function and decreased the fasting glucose level in NAFLD mice. Morphologically, our results showed that tyrosol could reduce the fat deposition and lipid droplets accumulation in liver tissue. The key regulating factors, JAK1 and STAT3, were increased in NAFLD mice, but tyrosol treatment could effectively prevent the upregulation. The expression levels of pro-inflammatory cytokine genes in liver tissue of the NAFLD mice were upregulated, which could be effectively prevented by the treatment with tyrosol. Overall, in the high-fat diet-induced NAFLD mouse model, tyrosol could improve the liver function and, more importantly, ameliorate the inflammatory response triggered by the high-fat diet. Although our data here are consistent with the previous report that tyrosol could exert beneficial effects on the NAFLD animal model, we also provide solid evidence that tyrosol is able to conquer the inflammatory response in liver, which is related to the high-fat-diet feeding. Tyrosol could be a promising candidate for the treatment of NAFLD in the future.

Fat and exposure to 4-nitroquinoline-1-oxide causes histologic and inflammatory changes in murine livers

Risk factors for liver cancer include tobacco use, alcohol consumption, obesity, and male sex. Administration of 4-nitroquinonline-1-oxide (4NQO) in drinking water mimics the effects of tobacco and leads to oral carcinoma in mice. This study compared the effects of diets high and low in saturated fat (HF and LF, respectively), and sex, on liver histopathology in 4NQO-treated mice and controls. We hypothesized that 4NQO would cause histopathological changes in liver, and that a HF diet would increase hepatic pathology when compared to the LF diet. Mice (C57Bl/6, 36/sex), were divided into a low fat (10 kcal% fat; LF) or high fat (60 kcal% fat, HF) diet. Mice were further subdivided into one of 3 water treatment groups for 17 weeks: water (control), vehicle (1.25% propylene glycol in water [PG]), or 4NQO in (50 μg/ml; 4NQO). All mice were subsequently given water alone for 6 more weeks. Upon euthanasia, livers were harvested, fixed, sectioned, and stained with hematoxylin and eosin (H&E). H&E slides were graded for histopathology; frozen liver samples were analyzed for triglyceride content. Trichrome stained sections were graded for fibrosis. CD3+ T cells, CD68+ macrophages, and Ly6+ neutrophils were detected by immunohistochemistry. Compared to water controls, 4NQO-treatment caused mouse liver histopathological changes such as fibrosis, and increases in hepatic neutrophils, T cells, and macrophages. HF diet exacerbated pathological changes compared to LF diet. Male controls, but not females, demonstrated severe steatosis and increased triglyceride content. 4NQO treatment decreased hepatic fat accumulation, even in animals on a HF diet. In conclusion, this murine model of oral cancer may serve as a model to study the effects of tobacco and diet on liver.

A High-Fat Diet Induces Muscle Mitochondrial Dysfunction and Impairs Swimming Capacity in Zebrafish: A New Model of Sarcopenic Obesity

Obesity is a highly prevalent disease that can induce metabolic syndrome and is associated with a greater risk of muscular atrophy. Mitochondria play central roles in regulating the physiological metabolism of skeletal muscle; however, whether a decreased mitochondrial function is associated with impaired muscle function is unclear. In this study, we evaluated the effects of a high-fat diet on muscle mitochondrial function in a zebrafish model of sarcopenic obesity (SOB). In SOB zebrafish, a significant decrease in exercise capacity and skeletal muscle fiber cross-sectional area was detected, accompanied by high expression of the atrophy-related markers Atrogin-1 and muscle RING-finger protein-1. Zebrafish with SOB exhibited inhibition of mitochondrial biogenesis and fatty acid oxidation as well as disruption of mitochondrial fusion and fission in atrophic muscle. Thus, our findings showed that muscle atrophy was associated with SOB-induced mitochondrial dysfunction. Overall, these results showed that the SOB zebrafish model established in this study may provide new insights into the development of therapeutic strategies to manage mitochondria-related muscular atrophy.

The Effects of High Fat Diet on the Liver of the White Rat Model Obesity

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease with the manifestation of over-accumulation of fat in the liver. AIM: The purpose of this study was to assess the degree of occurrence of steatosis in rats induced by a standard diet, a high-fat diet, and a modified high-fat diet. METHODS: This study used 18 white rats of the Wistar strain, divided into three groups, and fed for 9 weeks. Before feeding, all rats were measured their body weight, abdominal circumference, and body length. We measured body weight every week, while body length and waist circumference were measured every 2 weeks. After 9 weeks of diet, all rats were subjected to injection of Ketamine and examined for metabolic markers and histopathological examination of liver organs. RESULT: There was an increase in body weight of rats in the three groups with the average percentage increase in body weight in the three groups of rats before and after being fed a diet for 9 weeks found in Group 1 29.19% 1 (187−264.40 g), Group 2 by 19.12% (219.33−275 g), and Group 3 24.53% (213.33−275 g). Steatosis in Group 1 was 57.50% of hepatocytes containing macrovesicular fat droplets and called Grade 2 (moderate). In contrast, with a high-fat diet, steatosis occurred around 93.33%−95% of hepatocytes containing macrovesicular fat droplets and called steatosis Grade 3 (severe). CONCLUSION: The percentage of hepatocytes that had steatosis in obese rats induced by a high-fat diet was more significant than in obese models induced by a standard diet.

Altered Mitochondrial Quality Control in Rats with Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) Induced by High-Fat Feeding

Metabolic dysfunction-associated fatty liver disease (MAFLD) is defined as the presence of hepatic steatosis in addition to one of three metabolic conditions: overweight/obesity, type 2 diabetes mellitus, or metabolic dysregulation. Chronic exposure to excess dietary fatty acids may cause hepatic steatosis and metabolic disturbances. The alteration of the quality of mitochondria is one of the factors that could contribute to the metabolic dysregulation of MAFDL. This study was designed to determine, in a rodent model of MAFLD, the effects of a long-term high-fat diet (HFD) on some hepatic processes that characterize mitochondrial quality control, such as biogenesis, dynamics, and mitophagy. To mimic the human manifestation of MAFLD, the rats were exposed to both an HFD and a housing temperature within the rat thermoneutral zone (28–30 °C). After 14 weeks of the HFD, the rats showed significant fat deposition and liver steatosis. Concomitantly, some important factors related to the hepatic mitochondrial quality were markedly affected, such as increased mitochondrial reactive oxygen species (ROS) production and mitochondrial DNA (mtDNA) damage; reduced mitochondrial biogenesis, mtDNA copy numbers, mtDNA repair, and mitochondrial fusion. HFD-fed rats also showed an impaired mitophagy. Overall, the obtained data shed new light on the network of different processes contributing to the failure of mitochondrial quality control as a central event for mitochondrial dysregulation in MAFLD.

A Lard and Soybean Oil Mixture Alleviates Low-Fat-High-Carbohydrate Diet-Induced Nonalcoholic Fatty Liver Disease in Mice

Dietary habit is highly related to nonalcoholic fatty liver disease (NAFLD). Low-fat–high-carbohydrate (LFHC) diets could induce lean NAFLD in Asians. Previously, we found that a lard and soybean oil mixture reduced fat accumulation with a medium-fat diet; therefore, in this study, we evaluated the effect of a lard and soybean oil mixture (LFHC diet) on NAFLD and its underlying mechanisms. Mice in groups were fed with lard, soybean oil, or a lard and soybean oil mixture—an LFHC diet—separately. Our results showed that mixed oil significantly inhibited serum triglyceride, liver triglyceride, serum free fatty acids (FFAs), and liver FFAs compared with soybean oil or lard, and we found fewer inflammatory cells in mice fed with mixed oil. RNA-seq results indicate that mixed oil reduced FFAs transportation into the liver via decreasing liver fatty acid-binding protein 2 expression, inhibited oxidative phosphorylation via tumor necrosis factor receptor superfamily member 6 downregulation, and alleviated inflammation via downregulating inflammatory cytokine. The liquid chromatography–mass spectrometry results showed that the mixed oil promoted bile acid conjugated with taurine and glycine, thus activating G-protein-coupled bile acid receptor 1 for improved lipids metabolism. In conclusion, the lard and soybean oil mixture alleviated NAFLD.

Hepatic microRNA modulation might be an early event to non-alcoholic fatty liver disease development driven by high-fat diet in male mice

INTRODUCTION

Metabolic alterations caused by an imbalance of macronutrient consumption are often related to the modulation of microRNAs (miRNAs), which could alter mRNAs expression profile and accelerate the development of non-alcoholic fatty liver disease (NAFLD).

AIMS

This study aimed to investigate the contribution of miRNAs in modulating early stages of NAFLD in mice submitted to a high-fat diet (HFD).

METHODS AND RESULTS

Male Swiss mice, fed either a control diet or an HFD for 1, 3, 7, 15, 30, 56 days, were assessed for metabolic alterations, gene expression and NAFLD markers. A hepatocyte cell line was used to investigate the effects of miR-370 modulation on enzymes involved in β-oxidation. Body weight and adiposity were higher after 7 days of HFD. Fasting glucose and insulin increased after 3 and 7 days of HFD, respectively. While hepatic lipid content increased from the first day on, hepatic glycogen had a decrease after 3 days of HFD consumption. miR-370 and Let-7 expression increased with acute and chronic exposure to HFD, accompanied by carnitine palmitoyltransferase 1A (Cpt1a), acyl-CoA dehydrogenase very long chain (Acadvl) and protein kinase AMP-activated Catalytic Subunit 2 (Prkaa2) downregulation, while decreased miR-122 expression was accompanied by 1-acylglycerol-3-phosphate-O-acyltransferase (Agpat) upregulation after 56 days of HFD consumption, some of them confirmed by in vitro experiments. Despite fluctuations in TNFa and IL6 mRNA levels, molecular modulation was consistent with hepatic TG and NAFLD development.

CONCLUSION

Hepatic miR-370-122-Let7 miRNA modulation could be the first insult to NAFLD development, preceding changes in glycemic homeostasis and adiposity.

Metabolomic profiling of M. speciosa champ at different growth stages

Millettia speciosa Champ (M. speciosa) is an edible food and folk medicine and extracts from its roots exhibit a hepatoprotective effect. However, its metabolic growth process and the best harvest time have not been reported. This study systematically evaluated the metabolomic profiling of M. speciosa root extracts at different growth stages through the UPLC-Q-TOF-MS, nuclear magnetic resonance (NMR) and An orthogonal partial least squares-discriminant analysis (OPLS-DA). The results revealed there were significant differences among extracts from six ages of M. speciosa, and 110 compounds were identified. Pharmacological studies showed that 5-year and 20-year old M. speciosa roots may exhibit higher fat-lowering effects, while 5-year-old (M.s-5Y) showed better hepatoprotective activity in high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) mice. Hence, our study suggested that M.s-5Y may have potent efficacy in ameliorating NAFLD, which might be useful in determining the optimum time to harvest M. speciosa.