Long-term fermented soybean paste improves metabolic parameters associated with non-alcoholic fatty liver disease and insulin resistance in high-fat diet-induced obese mice

Recently, Korean traditional fermented soybean paste, called Doenjang, has attracted attention for its protective effect against diet-related chronic diseases such as obesity and type 2 diabetes. Long-term fermented soybean pastes (LFSPs) are made by fermentation with naturally-occurring microorganisms for several months, whereas short-term fermented soybean pastes (SFSPs) are produced by shorter-time fermentation inoculated with a starter culture. Here, we demonstrate that administration of LFSP, but not SFSP, protects high-fat diet (HFD)-fed obese mice against non-alcohol fatty liver disease (NAFLD) and insulin resistance. LFSP suppressed body weight gain in parallel with reduction in fat accumulation in mesenteric adipose tissue (MAT) and the liver via modulation of MAT lipolysis and hepatic lipid uptake. LFSP-treated mice also had improved glucose tolerance and increased adiponectin levels concomitantly with enhanced AMPK activation in skeletal muscle and suppressed expression of pro-inflammatory cytokines in skeletal muscle and the liver. LFSP also attenuated HFD-induced gut permeability and lowered serum lipopolysaccharide level, providing an evidence for its probiotic effects, which was supported by the observation that treatment of a probiotic mixture of LFSP-originated Bacillus strains protected mice against HFD-induced adiposity and glucose intolerance. Our findings suggest that the intake of LFSP, but not SFSP, offers protection against NAFLD and insulin resistance, which is an effect of long-term fermentation resulting in elevated contents of active ingredients (especially flavonoids) and higher diversity and richness of Bacillus probiotic strains compared to SFSP.     

Chromium attenuates high-fat diet-induced nonalcoholic fatty liver disease in KK/HlJ mice

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease associated with insulin resistance, oxidative stress, and inflammation. Evidence indicates that chromium has a role in the regulation of glucose and lipid metabolism and may improve insulin sensitivity. In this study, we report that chromium supplementation has a beneficial effect against NAFLD. We found that KK/HlJ mice developed obesity and progressed to NAFLD after feeding with high-fat diet for 8 weeks. High-fat-fed KK/HlJ mice showed hepatocyte injury and hepatic triglyceride accumulation, which was accompanied by insulin resistance, oxidative stress, and inflammation. Chromium supplementation prevented progression of NAFLD and the beneficial effects were accompanied by reduction of hepatic triglyceride accumulation, elevation of hepatic lipid catabolic enzyme, improvement of glucose and lipid metabolism, suppression of inflammation as well as resolution of oxidative stress, probably through enhancement of insulin signaling. Our findings suggest that chromium could serve as a hepatoprotective agent against NAFLD.     

Combination of metformin and genistein alleviates non-alcoholic fatty liver disease in high-fat diet-fed mice

Metformin (MET) and genistein (GEN) have a beneficial role in alleviating non-alcoholic fatty liver disease (NAFLD), but their combined effect on this disease has not yet been studied. The present study aimed to investigate the potential protective effects of combined MET and GEN on NAFLD in high-fat diet (HFD) fed mice. C57BL/6 male mice were fed on an HFD for 10 weeks. Animals were then divided into different groups and treated with MET (0.23%), GEN (0.2%) and MET+GEN (0.23% + 0.2%) for 3 months. Treatment with MET and GEN, alone or in combination significantly lowered body and liver weights and fasting blood glucose (FBG) in HFD mice. Combination therapy reduced liver triglyceride (TG) level and this effect was correlated with increased expression of carnitine palmitoyl transferase 1 (CPT1) gene, and reduced expression of fatty-acid synthase (FAS)and sterol regulatory element-binding protein-1c (SREBP-1c) genes. Combination therapy also affects gluconeogenesis pathway through decreasing expression of Glucose 6-phosphatase (G6Pase) and increasing phosphorylation of Glycogen synthase kinase 3β (GSK-3β). Furthermore, combination of MET and GEN ameliorates liver inflammation by switching macrophage into M2 phenotype, decreasing macrophage infiltration, reducing expression of pro-inflammatory cytokines and decreasing nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activity. In addition, combination therapy enhances phosphorylation of 5′ adenosine monophosphate-activated protein kinase (AMPK). Taken together, these findings suggest that the combination of MET and GEN have beneficial effects against NAFLD in HFD-fed model.     

Niemann-Pick C1-Like 1 deletion in mice prevents high-fat diet-induced fatty liver by reducing lipogenesis

Niemann-Pick C1-Like 1 (NPC1L1) mediates intestinal absorption of dietary and biliary cholesterol. Ezetimibe, by inhibiting NPC1L1 function, is widely used to treat hypercholesterolemia in humans. Interestingly, ezetimibe treatment appears to attenuate hepatic steatosis in rodents and humans without a defined mechanism. Overconsumption of a high-fat diet (HFD) represents a major cause of metabolic disorders including fatty liver. To determine whether and how NPC1L1 deficiency prevents HFD-induced hepatic steatosis, in this study, we fed NPC1L1 knockout (L1-KO) mice and their wild-type (WT) controls an HFD, and found that 24 weeks of HFD feeding causes no fatty liver in L1-KO mice. Hepatic fatty acid synthesis and levels of mRNAs for lipogenic genes are substantially reduced but hepatic lipoprotein-triglyceride production, fatty acid oxidation, and triglyceride hydrolysis remain unaltered in L1-KO versus WT mice. Strikingly, L1-KO mice are completely protected against HFD-induced hyperinsulinemia under both fed and fasted states and during glucose challenge. Despite similar glucose tolerance, L1-KO relative WT mice are more insulin sensitive and in the overnight-fasted state display significantly lower plasma glucose concentrations. In conclusion, NPC1L1 deficiency in mice prevents HFD-induced fatty liver by reducing hepatic lipogenesis, at least in part, through attenuating HFD-induced insulin resistance, a state known to drive hepatic lipogenesis through elevated circulating insulin levels.     

Dysregulated RNA polyadenylation contributes to metabolic impairment in non-alcoholic fatty liver disease

Pre-mRNA processing is an essential mechanism for the generation of mature mRNA and the regulation of gene expression in eukaryotic cells. While defects in pre-mRNA processing have been implicated in a number of diseases their involvement in metabolic pathologies is still unclear. Here, we show that both alternative splicing and alternative polyadenylation, two major steps in pre-mRNA processing, are significantly altered in non-alcoholic fatty liver disease (NAFLD). Moreover, we find that Serine and Arginine Rich Splicing Factor 10 (SRSF10) binding is enriched adjacent to consensus polyadenylation motifs and its expression is significantly decreased in NAFLD, suggesting a role mediating pre-mRNA dysregulation in this condition. Consistently, inactivation of SRSF10 in mouse and human hepatocytes in vitro, and in mouse liver in vivo, was found to dysregulate polyadenylation of key metabolic genes such as peroxisome proliferator-activated receptor alpha (PPARA) and exacerbate diet-induced metabolic dysfunction. Collectively our work implicates dysregulated pre-mRNA polyadenylation in obesity-induced liver disease and uncovers a novel role for SRSF10 in this process.     

The isoxazole based flavonoid derivative 1 ameliorates non-alcoholic fatty liver disease in high-fat diet-induced obese mice by regulating lipid metabolism and inflammatory responses

Globally, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease, and has attracted considerable research traction in the literature. However, no effective drugs have yet been approved by the Food and Drug Administration. In this study, a new isoxazole derivative (1), which activated AMPK and reduced gluconeogenesis levels, was evaluated in HFD-induced obese mice for NAFLD treatment. Our results showed that 1 reduced body weight gain and attenuated metabolic disorder in these mice. Underlying mechanisms revealed that 1 alleviated hepatic steatosis by activating AMPK, and inflammatory responses by inhibiting NF-κB. Our study suggested that 1 may be clinically valuable as an NAFLD therapeutic candidate.     

Silencing of hepatic fatty acid transporter protein 5 in vivo reverses diet-induced non-alcoholic fatty liver disease and improves hyperglycemia

Non-alcoholic fatty liver disease is a serious health problem linked to obesity and type 2 diabetes. To investigate the biological outcome and therapeutic potential of hepatic fatty acid uptake inhibition, we utilized an adeno-associated virus-mediated RNA interference technique to knock down the expression of hepatic fatty acid transport protein 5 in vivo prior to or after establishing non-alcoholic fatty liver disease in mice. Using this approach, we demonstrate here the ability to achieve specific, non-toxic, and persistent knockdown of fatty acid transport protein 5 in mouse livers from a single adeno-associated virus injection, resulting in a marked reduction of hepatic dietary fatty acid uptake, reduced caloric uptake, and concomitant protection from diet-induced non-alcoholic fatty liver disease. Importantly, knockdown of fatty acid transport protein 5 was also able to reverse already established non-alcoholic fatty liver disease, resulting in significantly improved whole-body glucose homeostasis. Thus, continued activity of hepatic fatty acid transport protein 5 is required to sustain caloric uptake and fatty acid flux into the liver during high fat feeding and may present a novel avenue for the treatment of non-alcoholic fatty liver disease.     

Hydroxytyrosol prevents diet-induced metabolic syndrome and attenuates mitochondrial abnormalities in obese mice

A Mediterranean diet rich in olive oil has profound influence on health outcomes including metabolic syndrome. However, the active compound and detailed mechanisms still remain unclear. Hydroxytyrosol (HT), a major polyphenolic compound in virgin olive oil, has received increased attention for its antioxidative activity and regulation of mitochondrial function. Here, we investigated whether HT is the active compound in olive oil exerting a protective effect against metabolic syndrome. In this study, we show that HT could prevent high-fat-diet (HFD)-induced obesity, hyperglycemia, hyperlipidemia, and insulin resistance in C57BL/6 J mice after 17 weeks supplementation. Within liver and skeletal muscle tissues, HT could decrease HFD-induced lipid deposits through inhibition of the SREBP-1c/FAS pathway, ameliorate HFD-induced oxidative stress by enhancing antioxidant enzyme activities, normalize expression of mitochondrial complex subunits and mitochondrial fission marker Drp1, and eventually inhibit apoptosis activation. Moreover, in muscle tissue, the levels of mitochondrial carbonyl protein were decreased and mitochondrial complex activities were significantly improved by HT supplementation. In db/db mice, HT significantly decreased fasting glucose, similar to metformin. Notably, HT decreased serum lipid, at which metformin failed. Also, HT was more effective at decreasing the oxidation levels of lipids and proteins in both liver and muscle tissue. Similar to the results in the HFD model, HT decreased muscle mitochondrial carbonyl protein levels and improved mitochondrial complex activities in db/db mice. Our study links the olive oil component HT to diabetes and metabolic disease through changes that are not limited to decreases in oxidative stress, suggesting a potential pharmaceutical or clinical use of HT in metabolic syndrome treatment.     

Proteoglycan 4 deficiency protects against glucose intolerance and fatty liver disease in diet-induced obese mice

Objective

Proteoglycan 4 (Prg4) has emerged from human association studies as a possible factor contributing to weight gain, dyslipidemia and insulin resistance. In the current study, we investigated the causal role of Prg4 in controlling lipid and glucose metabolism in mice.

Nonalcoholic fatty liver disease and the metabolic syndrome

PURPOSE OF REVIEW: Clinical, epidemiological and biochemical data strongly support the concept that nonalcoholic fatty liver disease is the hepatic manifestation of the metabolic syndrome. Insulin resistance is the common factor connecting obesity, diabetes, hypertension and dyslipidemia with fatty liver and the progression of hepatic disease to steatohepatitis, fibrosis, cirrhosis and hepatocellular carcinoma. RECENT FINDINGS: The association of nonalcoholic fatty liver disease with the features of the metabolic syndrome has been confirmed in several epidemiological studies. The diagnostic and clinical significance of raised liver enzymes has been questioned; advanced hepatic disease may also be present in individuals with ultrasonographically detected steatosis and normal aminotransferase levels. The role of adipokines (leptin, adiponectin) and cytokines (tumor necrosis factor-alpha, interleukin-6, transforming growth factor-beta) in disease progression is probably pivotal, mediated by oxidative stress. The importance of iron accumulation in this process has not been confirmed. Treatments aimed at weight loss remain a primary option; among pharmacological interventions, insulin sensitizers (glitazones and metformin) have confirmed beneficial effects on both biochemical and histological data, but new treatments are on the horizon. SUMMARY: Nonalcoholic fatty liver disease prevalence in Western countries is high and there is a trend towards a further increase, with millions of people at risk of advanced liver disease. The epidemiological evidence, the lifestyle origin of the disease and the cost of pharmacotherapy make prevention a primary goal, and will contribute to making behavior therapy the background treatment. We need specific programs and carefully controlled, randomized studies to tackle simultaneously all the components of the metabolic syndrome.     

Influence of age on the association of retinol-binding protein 4 with metabolic syndrome

Objective: The relationships of retinol‐binding protein 4 (RBP4) with insulin sensitivity and body fat distribution have been investigated in a few recent studies with conflicting results. This may have been due to differences in ages of the subjects in the different studies. The aim of this study was to investigate whether the association of RBP4 and insulin sensitivity and percent trunk fat are influenced by age. Methods and Procedures: Cross‐sectional analyses of 48 young subjects and 55 elderly subjects. Insulin sensitivity was determined by a hyperinsulinemic–euglycemic clamp. Body fat distribution was determined by a dual‐energy X‐ray absorptiometry (DXA). Results: In the young subjects, RBP4 levels were associated with insulin sensitivity (r = ?0.30, P = 0.04), percent trunk fat (r = 0.54, P < 0.001), triglycerides (r = 0.44, P = 0.003), low‐density lipoprotein (r = 0.38, P = 0.01). In contrast, in the elderly subjects there was no correlation between RBP4 levels and insulin sensitivity (r = ?0.18, P = 0.20), percent trunk fat (r = 0.00, P = 0.10), triglycerides (r = 0.25, P = 0.10), and low‐density lipoprotein (r = ?0.11, P = 0.47). Discussion: The associations of RBP4 with insulin sensitivity, percent trunk fat, and lipid levels are influenced by age.     

Study on the correlation between urinary retinol-binding protein and nonalcoholic fatty liver disease

BackgroundNonalcoholic fatty liver disease (NAFLD) affects human health worldwide. Our objective was to explore the correlation between urinary retinol-binding protein (URBP) and NAFLD.MethodsThis cross-sectional study included 445 NAFLD patients and 911 healthy controls. The URBP level and other parameters were measured.ResultsThe URBP level (expressed by the RBP/creatinine ratio) was higher in the NAFLD patients compared with the non-NAFLD patients. The urinary RBP/creatinine ratio was an independent risk factor for NAFLD after univariate and multivariate regression analysis, with the or values of 2.271 (1.795-2.872, P < 0.001) and 2.338 (1.775-3.080, P < 0.001), respectively. The prevalence of the urinary RBP/creatinine ratio (groups 1, 2, 3, 4) was 20.0%, 17.3%, 27.3%, and 35.4%, respectively (P < 0.001), and the prevalence of NAFLD in the high urinary RBP/creatinine ratio group was significantly higher than that in the low urinary RBP/creatinine ratio group.ConclusionsOur results revealed that the urinary RBP/creatinine ratio was an independent risk factor for NAFLD.     

Effects of pre-germinated brown rice treatment high-fat diet-induced metabolic syndrome in C57BL/6J mice

To investigate using pre-germinated brown rice (PGBR) to treat metabolic syndrome, we fed one group of mice standard-regular-diet (SRD) for 20 weeks and another group of mice high-fat-diet (HFD) for 16 weeks. We subdivided them into HFD group and HFD + PGBR group whose dietary carbohydrate was replaced with PGBR for 4 weeks. The HFD group gained more weight, had higher blood pressure, heart rate, blood glucose and lipids, liver levels of TG, feces TG and bile acid, lower adipose levels of adipocytokine, lower skeletal muscle IR, IRS-1, IRS-2, PI3 K, Akt/PKB, GLUT-1, GLUT-4, GCK and PPAR-γ; higher liver SREBP-1, SCD-1, FAS, HMGCR, LDLR, CYP7α1 and PPAR-α, and higher adipose SREBP-1, SCD-1, FAS, and lower adipose PPAR-α and adiponectin. The HFD + PGBR group had clearly improved blood pressure, biochemical parameters and above proteins expressions. PGBR successful treatment of metabolic syndrome was achieved through improvements in glucose and lipid synthesis and metabolism.     

Chlorella modulates insulin signaling pathway and prevents high-fat diet-induced insulin resistance in mice

Aims

The search for natural agents that minimize obesity-associated disorders is receiving special attention. In this regard, the present study aimed to evaluate the prophylactic effect of Chlorella vulgaris (CV) on body weight, lipid profile, blood glucose and insulin signaling in liver, skeletal muscle and adipose tissue of diet-induced obese mice.

Main methods

Balb/C mice were fed either with standard rodent chow diet or high-fat diet (HFD) and received concomitant treatment with CV for 12 consecutive weeks. Triglyceride, free fatty acid, total cholesterol and fractions of cholesterol were measured using commercial assay. Insulin and leptin levels were determined by enzyme-linked immunosorbent assay (ELISA). Insulin and glucose tolerance tests were performed. The expression and phosphorylation of IRβ, IRS-1 and Akt were determined by Western blot analyses.

Key findings

Herein we demonstrate for the first time in the literature that prevention by CV of high-fat diet-induced insulin resistance in obese mice, as shown by increased glucose and insulin tolerance, is in part due to the improvement in the insulin signaling pathway at its main target tissues, by increasing the phosphorylation levels of proteins such as IR, IRS-1 and Akt. In parallel, the lower phosphorylation levels of IRS-1^ser307 were observed in obese mice. We also found that CV administration prevents high-fat diet-induced dyslipidemia by reducing triglyceride, cholesterol and free fatty acid levels.

Significance

We propose that the modulatory effect of CV treatment preventing the deleterious effects induced by high-fat diet is a good indicator for its use as a prophylactic–therapeutic agent against obesity-related complications.     

Role of fatty acid transport protein 4 in metabolic tissues: insights into obesity and fatty liver disease

Fatty acid (FA) metabolism is a series of processes that provide structural substances, signalling molecules and energy. Ample evidence has shown that FA uptake is mediated by plasma membrane transporters including FA transport proteins (FATPs), caveolin-1, fatty-acid translocase (FAT)/CD36, and fatty-acid binding proteins. Unlike other FA transporters, the functions of FATPs have been controversial because they contain both motifs of FA transport and fatty acyl-CoA synthetase (ACS). The widely distributed FATP4 is not a direct FA transporter but plays a predominant function as an ACS. FATP4 deficiency causes ichthyosis premature syndrome in mice and humans associated with suppression of polar lipids but an increase in neutral lipids including triglycerides (TGs). Such a shift has been extensively characterized in enterocyte-, hepatocyte-, and adipocyte-specific Fatp4-deficient mice. The mutants under obese and non-obese fatty livers induced by different diets persistently show an increase in blood non-esterified free fatty acids and glycerol indicating the lipolysis of TGs. This review also focuses on FATP4 role on regulatory networks and factors that modulate FATP4 expression in metabolic tissues including intestine, liver, muscle, and adipose tissues. Metabolic disorders especially regarding blood lipids by FATP4 deficiency in different cell types are herein discussed. Our results may be applicable to not only patients with FATP4 mutations but also represent a model of dysregulated lipid homeostasis, thus providing mechanistic insights into obesity and development of fatty liver disease.     

Macrophage-specific MyD88 deletion and pharmacological inhibition prevents liver damage in non-alcoholic fatty liver disease via reducing inflammatory response

Activation of the innate immune system through toll-like receptors (TLRs) has been repeatedly demonstrated in non-alcoholic fatty liver disease (NAFLD) and several TLRs have been shown to contribute. Myeloid differentiation primary response 88 (MyD88) is as an adapter protein for the activation of TLRs and bridges TLRs to NF-κB-mediated inflammation in macrophages. However, whether myeloid cell MyD88 contributes to NAFLD are largely unknown. To test this approach, we generated macrophage-specific MyD88 knockout mice and show that these mice are protected against high-fat diet (HFD)-induced hepatic injury, lipid accumulation, and fibrosis. These protective effects were associated with reduced macrophage numbers in liver tissues and surpassed inflammatory responses. In cultured macrophages, saturated fatty acid palmitate utilizes MyD88 to activate NF-κB and induce inflammatory and fibrogenic factors. In hepatocytes, these factors may cause lipid accumulation and a further elaboration of inflammatory cytokines. In hepatic stellate cells, macrophage-derived factors, especially TGF-β, cause activation and hepatic fibrosis. We further show that pharmacological inhibition of MyD88 is also able to reduce NAFLD injury in HFD-fed mice. Therefore, our study has provided empirical evidence that macrophage MyD88 participates in HFD-induced NAFLD and could be targeted to prevent the development and progression of NAFLD/NASH.     

有氧运动对非酒精性脂肪肝小鼠肝脏CNPY2-PERK通路的影响

目的:探讨有氧运动对高脂诱导小鼠非酒精性脂肪肝(NAFLD)的影响及其肝脏冠层成纤维细胞生长因子信号调节器2 (CNPY2)-PKR样内质网激酶(PERK)机制。方法:8周龄雄性C57BL/6J小鼠随机分为对照组(C)、对照+运动组(CE),NAFLD模型组(M)和NAFLD模型+运动组(ME),每组10只。C组和CE组小鼠给予普通饲料,M组和ME组小鼠给予高脂饲料(脂肪供能占比为60%),连续喂养18周至实验结束,取小鼠血清和肝脏。CE组和ME组从第10周起进行有氧跑台训练(12 m/min,每次60 min,每周5 d)。检测小鼠血清总胆固醇(TC)、总甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-c)、低密度脂蛋白胆固醇(LDL-c)、丙氨酸氨基转移酶(ALT)和天冬氨酸转氨酶(AST)水平;观察小鼠肝组织病理学形态;检测肝组织CNPY2、PERK、p-eIF2a、CHOP、CNPY2 mRNA、PERK mRNA表达和CNPY2、PERK的阳性表达。结果:与C组比较,M组小鼠的血清LDL-c、TC、TG、ALT和AST水平显著升高(P<0.05),HDL-c水平显著降低(...