n-3 Fatty acids combined with flavan-3-ols prevent steatosis and liver injury in a murine model of NAFLD

Refined diet consumption increases neuroinflammatory signalling through bile acid dysmetabolism

Over recent decades, dietary patterns have changed significantly due to the increasing availability of convenient, ultra-processed refined foods. Refined foods are commonly depleted of key bioactive compounds, which have been associated with several deleterious health conditions. As the gut microbiome can influence the brain through a bidirectional communication system known as the 'microbiota-gut-brain axis', the consumption of refined foods has the potential to affect cognitive health. In this study, multi-omics approaches were employed to assess the effect of a refined diet on the microbiota-gut-brain axis, with a particular focus on bile acid metabolism. Mice maintained on a refined low-fat diet (rLFD), consisting of high sucrose, processed carbohydrates and low fibre content, for eight weeks displayed significant gut microbial dysbiosis, as indicated by diminished alpha diversity metrics (p < 0.05) and altered beta diversity (p < 0.05) when compared to mice receiving a chow diet. Changes in gut microbiota composition paralleled modulation of the metabolome, including a significant reduction in short-chain fatty acids (acetate, propionate and n-butyrate; p < 0.001) and alterations in bile acid concentrations. Interestingly, the rLFD led to dysregulated bile acid concentrations across both the colon (p < 0.05) and the brain (p < 0.05) which coincided with altered neuroinflammatory gene expression. In particular, the concentration of TCA, TDCA and T-α-MCA was inversely correlated with the expression of NF-κB1, a key transcription factor in neuroinflammation. Overall, our results suggest a novel link between a refined low-fat diet and detrimental neuronal processes, likely in part through modulation of the microbiota-gut-brain axis and bile acid dysmetabolism.

Dietary chlorogenic acid alleviates high-fat diet-induced steatotic liver disease by regulating metabolites and gut microbiota

The high-fat diet would lead to excessive fat storage in the liver to form metabolic dysfunction-associated steatotic liver disease (MASLD), and the trend is burgeoning. The aim of the study is to investigate the effects of chlorogenic acid (CGA) on metabolites and gut microorganisms in MASLD mice induced by a high-fat diet. In comparison to the HF group, the TC (total cholesterol), TG (total triglycerides), LDL-C (low-density lipoprotein cholesterol), AST (aspartate aminotransferase) and ALT (alanine transaminase) levels were reduced after CGA supplement. CGA led to an increase in l-phenylalanine, l-tryptophan levels, and promoted fatty acid degradation. CGA increased the abundance of the Muribaculaceae, Bacteroides and Parabacteroides. Changes in these microbes were significantly associated with the liver metabolites level and lipid profile level. These data suggest important roles for CGA regulating the gut microbiota, liver and caecum content metabolites, and TG-, TC- and LDL-C lowering function.

Docosahexaenoic Acid Modulates Nonalcoholic Fatty Liver Disease by Suppressing Endocannabinoid System

SCOPE

Endocannabinoid signaling regulates energy homeostasis, and is tightly associated with nonalcoholic fatty liver disease (NAFLD). The study previously finds that supplementation of docosahexaenoic acid (DHA) has superior function to ameliorate NAFLD compared with eicosapentaenoic acid (EPA), however, the underlying mechanism remains elusive. The present study aims to investigate whether DHA intervention alleviates NAFLD via endocannabinoid system.

METHODS AND RESULTS

In a case-control study, the serum endocannabinoid ligands in 60 NAFLD and 60 healthy subjects are measured. Meanwhile, NAFLD model is established in mice fed a high-fat and -cholesterol diet (HFD) for 9 weeks. DHA or EPA is administrated for additional 9 weeks. Serum primary endocannabinoid ligands, namely anandamide (AEA) and 2-arachidoniylglycerol (2-AG), are significantly higher in individuals with NAFLD compared with healthy controls. NAFLD model shows that serum 2-AG concentrations and adipocyte cannabinoid receptor 1 expression levels are significantly lower in DHA group compared with HFD group. Lipidomic and targeted ceramide analyses further confirm that endocannabinoid signaling inhibition has exerted deletion of hepatic C16:0-ceramide contents, resulting in down-regulation of de novo fatty acid synthesis and up-regulation of fatty acid β-oxidation related protein expression levels.

CONCLUSIONS

This work elucidates that DHA has improved NAFLD by suppressing endocannabinoid system.

Pharmacology of bioactive compounds from plant extracts for improving non-alcoholic fatty liver disease through endoplasmic reticulum stress modulation: A comprehensive review

Background

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver condition with significant clinical implications. Emerging research indicates endoplasmic reticulum (ER) stress as a critical pathogenic factor governing inflammatory responses, lipid metabolism and insulin signal transduction in patients with NAFLD. ER stress-associated activation of multiple signal transduction pathways, including the unfolded protein response, disrupts lipid homeostasis and substantially contributes to NAFLD development and progression. Targeting ER stress for liver function enhancement presents an innovative therapeutic strategy. Notably, the natural bioactive compounds of plant extracts have shown potential for treating NAFLD by reducing the level of ER stress marker proteins and mitigating inflammation, stress responses, and de novo lipogenesis. However, owing to limited comprehensive reviews, the effectiveness and pharmacology of these bioactive compounds remain uncertain.

Objectives

To address the abovementioned challenges, the current review categorizes the bioactive compounds of plant extracts by chemical structures and properties into flavonoids, phenols, terpenoids, glycosides, lipids and quinones and examines their ameliorative potential for NAFLD under ER stress.

Methods

This review systematically analyses the literature on the interactions of bioactive compounds from plant extracts with molecular targets under ER stress, providing a holistic view of NAFLD therapy.

Results

Bioactive compounds from plant extracts may improve NAFLD by alleviating ER stress; reducing lipid synthesis, inflammation, oxidative stress and apoptosis and enhancing fatty acid metabolism. This provides a multifaceted approach for treating NAFLD.

Conclusion

This review underscores the role of ER stress in NAFLD and the potential of plant bioactive compounds in treating this condition. The molecular mechanisms by which plant bioactive compounds interact with their ER stress targets provide a basis for further exploration in NAFLD management.

Pharmacological and genetic increases in liver NADPH levels ameliorate NASH progression in female mice

Non-alcoholic steatohepatitis (NASH) is one of the fastest growing liver diseases worldwide, and oxidative stress is one of NASH main key drivers. Nicotinamide adenine dinucleotide phosphate (NADPH) is the ultimate donor of reductive power to a number of antioxidant defences. Here, we explored the potential of increasing NADPH levels to prevent NASH progression. We used nicotinamide riboside (NR) supplementation or a G6PD-tg mouse line harbouring an additional copy of the human G6PD gene. In a NASH mouse model induced by feeding mice a methionine-choline deficient (MCD) diet for three weeks, both tools increased the hepatic levels of NADPH and ameliorated the NASH phenotype induced by the MCD intervention, but only in female mice. Boosting NADPH levels in females increased the liver expression of the antioxidant genes Gsta3, Sod1 and Txnrd1 in NR-treated mice, or of Gsr for G6PD-tg mice. Both strategies significantly reduced hepatic lipid peroxidation. NR-treated female mice showed a reduction of steatosis accompanied by a drop of the hepatic triglyceride levels, that was not observed in G6PD-tg mice. NR-treated mice tended to reduce their lobular inflammation, showed a reduction of the NK cell population and diminished transcription of the damage marker Lcn2. G6PD-tg female mice exhibited a reduction of their lobular inflammation and hepatocyte ballooning induced by the MCD diet, that was related to a reduction of the monocyte-derived macrophage population and the Tnfa, Ccl2 and Lcn2 gene expression. As conclusion, boosting hepatic NADPH levels attenuated the oxidative lipid damage and the exhausted antioxidant gene expression specifically in female mice in two different models of NASH, preventing the progression of the inflammatory process and hepatic injury.

n-3 polyunsaturated fatty acids in phospholipid or triacylglycerol form attenuate nonalcoholic fatty liver disease via mediating cannabinoid receptor 1/adiponectin/ceramide pathway

n-3 polyunsaturated fatty acids (PUFA) have shown to exert beneficial effects in the treatment of nonalcoholic fatty liver disease (NAFLD). Supplements of n-3 PUFA occur in either phospholipid or triacylglycerol form. The present study aimed to compare whether the different n-3 PUFA of marine-origin, namely krill oil, DHA/EPA-phospholipid (PL), and EPA/DHA-triacylglycerol (TAG) forms had differential abilities to ameliorate NAFLD. The NAFLD model was established in mice fed a high-fat and high-cholesterol diet (HFD). The mice showed evidence of weight gain, dyslipidemia, insulin resistance and hepatic steatosis after 9 weeks of HFD, while the three forms of the n-3 PUFA reduced hepatic TAG accumulation, fatty liver and improved insulin instance, and hepatic biomarkers after 9 weeks of intervention. Of these, krill oil intervention significantly reduced adipocyte hypertrophy and hepatic steatosis in comparison with DHA/EPA-PL and EPA/DHA-TAG groups. Importantly, only krill oil intervention significantly reduced serum alanine transaminase, aspartate transaminase concentrations and low-density lipoprotein-cholesterol, compared with the HFD group. Supplemental n-3 PUFA lowered circulating anandamide (AEA) and 2-arachidonoylglycerol (2-AG) concentrations, compared with the HFD group, which was associated with down-regulating CB1 and upregulating adiponectin expressions in adipose tissue. Besides, targeted lipidomic analyses indicated that the increased adiponectin levels were accompanied by reductions in hepatic ceramide levels. The reduced ceramide levels were associated with inhibiting lipid synthesis and increasing fatty acid β-oxidation, finally inhibiting TAG accumulation in the liver. Through mediating CB1/adiponectin/ceramide pathway, the present study suggested that administration of krill oil had superior health effects in the therapy of NAFLD in comparison with DHA/EPA-PL and EPA/DHA-TAG.

New Insights into Nutrition and Gut-Liver Axis: A Focus on Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver disease and represents a public health issue in Western industrialized countries [...].

Regulatory Effects and Molecular Mechanisms of Tea and Its Active Compounds on Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease, is a multifactorial disease resulting from the interaction between environment, genetic background, and metabolic stress. Most treatments for NAFLD include dietary intervention and exercise show limited efficacy due to the complex mechanisms involved in NAFLD. Meanwhile, drug therapy is accompanied by serious side effects. The development of high-efficiency natural supplements is a sustainable strategy for the prevention and treatment of NAFLD. As the second most consumed beverage, tea has health benefits that have been widely recognized. Nevertheless, the intervention of tea active compounds in NAFLD has received limited attention. Tea contains abundant bioactive compounds with potential effects on NAFLD, such as catechins, flavonoids, theanine, tea pigments, and tea polysaccharides. We reviewed the intrinsic and environmental factors and pathogenic mechanisms that affect the occurrence and development of NAFLD, and summarized the influences of exercise, drugs, diet, and tea drinking on NAFLD. On this basis, we further analyzed the potential effects and molecular regulatory mechanisms of tea active compounds on NAFLD and proposed future development directions. This review hopes to provide novel insights into the development and application of tea active compounds in the prevention and treatment of NAFLD.

Is it possible to treat nonalcoholic liver disease using a flavanol-based nutraceutical approach? Basic and clinical data

Nonalcoholic fatty liver disease (NAFLD) is characterized by a spectrum of diseases, ranging from simple steatosis to hepatocellular carcinoma. The main factors for NAFLD are closely related to obesity, insulin resistance, intestinal microbiota alterations, hyperinsulinism, low-grade systemic inflammation, nitroxidative stress, lipid peroxidation, and mitochondrial dysfunction. Currently, the treatment of NAFLD is based on diet and exercise because, to date, there is no specific pharmacological agent, already approved, that raises the need for new therapeutic strategies. Nutraceuticals, such as polyphenols, have potential beneficial effects for health. In this article, the beneficial effects of epigallocatechin-3-gallate (EGCG) and (-)-epicatechin (EC) are discussed. EGCG is the main catechin in green tea, which has shown in various studies its potential effect preventing and treating NAFLD since it has shown antihyperlipidemic, anti-inflammatory, antifibrotic, antioxidant, and improvement of liver lipid metabolism. However, it has been found that excessive consumption may cause hepatotoxicity. EC is widely distributed in nature (fruits and vegetables). This flavanol has shown many beneficial effects, including antihypertensive, anti-inflammatory, anti-hyperglycemic, antithrombotic, and antifibrotic properties. It increases mitochondrial biogenesis, and it also has effects on the regulation of synthesis and metabolism of lipids. This flavanol is a nontoxic substance; it has been classified by the United States Food and Drug Administration as harmless. The EC-induced effects can be useful for the prevention and/or treatment of NAFLD.

Wholegrain fermentation affects gut microbiota composition, phenolic acid metabolism and pancreatic beta cell function in a rodent model of type 2 diabetes

The intestinal microbiota plays an important role in host metabolism via production of dietary metabolites. Microbiota imbalances are linked to type 2 diabetes (T2D), but dietary modification of the microbiota may promote glycemic control. Using a rodent model of T2D and an in vitro gut model system, this study investigated whether differences in gut microbiota between control mice and mice fed a high-fat, high-fructose (HFHFr) diet influenced the production of phenolic acid metabolites following fermentation of wholegrain (WW) and control wheat (CW). In addition, the study assessed whether changes in metabolite profiles affected pancreatic beta cell function. Fecal samples from control or HFHFr-fed mice were fermented in vitro with 0.1% (w/v) WW or CW for 0, 6, and 24 h. Microbiota composition was determined by bacterial 16S rRNA sequencing and phenolic acid (PA) profiles by UPLC-MS/MS. Cell viability, apoptosis and insulin release from pancreatic MIN6 beta cells and primary mouse islets were assessed in response to fermentation supernatants and selected PAs. HFHFr mice exhibited an overall dysbiotic microbiota with an increase in abundance of proteobacterial taxa (particularly Oxalobacteraceae) and Lachnospiraceae, and a decrease in Lactobacillus. A trend toward restoration of diversity and compositional reorganization was observed following WW fermentation at 6 h, although after 24 h, the HFHFr microbiota was monodominated by Cupriavidus. In parallel, the PA profile was significantly altered in the HFHFr group compared to controls with decreased levels of 3-OH-benzoic acid, 4-OH-benzoic acid, isoferulic acid and ferulic acid at 6 h of WW fermentation. In pancreatic beta cells, exposure to pre-fermentation supernatants led to inhibition of insulin release, which was reversed over fermentation time. We conclude that HFHFr mice as a model of T2D are characterized by a dysbiotic microbiota, which is modulated by the in vitro fermentation of WW. The differences in microbiota composition have implications for PA profile dynamics and for the secretory capacity of pancreatic beta cells.

DHA-Enriched Fish Oil Ameliorates Deficits in Cognition Associated with Menopause and the APOE4 Genotype in Rodents

Female APOE4 carriers have a greater predisposition to developing Alzheimer’s disease (AD) compared to their male counterparts, which may partly be attributed to menopause. We previously reported that a combination of menopause and APOE4 led to an exacerbation of cognitive and neurological deficits, which were associated with reduced brain DHA and DHA:AA ratio. Here, we explored whether DHA-enriched fish oil (FO) supplementation mitigated the detrimental impact of these risk factors. Whilst DHA-enriched fish oil improved recognition memory (NOR) in APOE4 VCD (4-vinylcyclohexene diepoxide)-treated mice (p < 0.05), no change in spatial working memory (Y-maze) was observed. FO supplementation increased brain DHA and nervonic acid and the DHA:AA ratio. The response of key bioenergetic and blood−brain barrier related genes and proteins provided mechanistic insights into these behavioural findings, with increased BDNF protein concentration as well as mitigation of aberrant Erβ, Cldn1 and Glut-5 expression in APOE4 mice receiving fish oil supplementation (p < 0.05). In conclusion, supplementation with a physiologically relevant dose of DHA-enriched fish oil appears to offer protection against the detrimental effects of menopause, particularly in “at-risk” APOE4 female carriers.

Unveiling the Role of the Fatty Acid Binding Protein 4 in the Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD), the main cause of chronic liver disease worldwide, is a progressive disease ranging from fatty liver to steatohepatitis (metabolic-associated steatohepatitis; MASH). Nevertheless, it remains underdiagnosed due to the lack of effective non-invasive methods for its diagnosis and staging. Although MAFLD has been found in lean individuals, it is closely associated with obesity-related conditions. Adipose tissue is the main source of liver triglycerides and adipocytes act as endocrine organs releasing a large number of adipokines and pro-inflammatory mediators involved in MAFLD progression into bloodstream. Among the adipocyte-derived molecules, fatty acid binding protein 4 (FABP4) has been recently associated with fatty liver and additional features of advanced stages of MAFLD. Additionally, emerging data from preclinical studies propose FABP4 as a causal actor involved in the disease progression, rather than a mere biomarker for the disease. Therefore, the FABP4 regulation could be considered as a potential therapeutic strategy to MAFLD. Here, we review the current knowledge of FABP4 in MAFLD, as well as its potential role as a therapeutic target for this disease.

Differential Influence of Soluble Dietary Fibres on Intestinal and Hepatic Carbohydrate Response

Refined foods are commonly depleted in certain bioactive components that are abundant in 'natural' (plant) foods. Identification and addition of these 'missing' bioactives in the diet is, therefore, necessary to counteract the deleterious impact of convenience food. In this study, multiomics approaches were employed to assess the addition of the popular supplementary soluble dietary fibers inulin and psyllium, both in isolation and in combination with a refined animal feed. A 16S rRNA sequencing and ¹H NMR metabolomic investigation revealed that, whilst inulin mediated an increase in Bifidobacteria, psyllium elicited a broader microbial shift, with Parasutterella and Akkermansia being increased and Enterorhabdus and Odoribacter decreased. Interestingly, the combination diet benefited from both inulin and psyllium related microbial changes. Psyllium mediated microbial changes correlated with a reduction of glucose (R -0.67, -0.73, respectively, p < 0.05) and type 2 diabetes associated metabolites: 3-methyl-2-oxovaleric acid (R -0.72, -0.78, respectively, p < 0.05), and citrulline (R -0.77, -0.71, respectively, p < 0.05). This was in line with intestinal and hepatic carbohydrate response (e.g., Slc2a2, Slc2a5, Khk and Fbp1) and hepatic lipogenesis (e.g., Srebf1 and Fasn), which were significantly reduced under psyllium addition. Although established in the liver, the intestinal response associated with psyllium was absent in the combination diet, placing greater significance upon the established microbial, and subsequent metabolomic, shift. Our results therefore highlight the heterogeneity that exists between distinct dietary fibers in the context of carbohydrate uptake and metabolism, and supports psyllium containing combination diets, for their ability to negate the impact of a refined diet.

APOE4 genotype exacerbates the impact of menopause on cognition and synaptic plasticity in APOE-TR mice

The impact of sex and menopausal status in Alzheimer's disease remains understudied despite increasing evidence of greater female risk, particularly in APOE4 carriers. Utilizing female APOE-TR mice maintained on a high-fat diet background we induced ovarian failure through repeated VCD injections, to mimic human menopause. At 12 months of age, recognition memory and spatial memory were assessed using object recognition, Y-maze spontaneous alternation, and Barnes maze. A VCD*genotype interaction reduced the recognition memory (P < .05), with APOE4 VCD-treated animals unable to distinguish between novel and familiar objects. APOE4 mice displayed an additional 37% and 12% reduction in Barnes (P < .01) and Y-maze (P < .01) performance, indicative of genotype-specific spatial memory impairment. Molecular analysis indicated both VCD and genotype-related deficits in synaptic plasticity with BDNF, Akt, mTOR, and ERK signaling compromised. Subsequent reductions in the transcription factors Creb1 and Atf4 were also evident. Furthermore, the VCD*genotype interaction specifically diminished Ephb2 expression, while Fos, and Cnr1 expression reduced as a consequence of APOE4 genotype. Brain DHA levels were 13% lower in VCD-treated animals independent of genotype. Consistent with this, we detected alterations in the expression of the DHA transporters Acsl6 and Fatp4. Our results indicate that the combination of ovarian failure and APOE4 leads to an exacerbation of cognitive and neurological deficits.

Polyphenols in the prevention and treatment of non-alcoholic fatty liver disease: An update of preclinical and clinical studies

BACKGROUND & AIMS

The prevention and treatment of non-alcoholic fatty liver disease (NAFLD) has become one of the most urgent problems to be solved. To date, only a lifestyle modification related to diet and physical activity is considered for these patients. Polyphenols are a group of plant natural products that when regularly consumed has been related to a reduction in the risk of several metabolic disorders associated with NAFLD. In this study, we aimed to present an overview of the relationship between polyphenols and NAFLD with current approaches.

METHODS

We performed a comprehensive literature search for articles on polyphenols and NAFLD published in English between January 2018 to August 2020. Keywords included in this review: "Phenolic" OR "Polyphenol" AND "Non-Alcoholic Fatty Liver Disease". The editorials, communications and conference abstracts were excluded.

RESULTS

Different polyphenols decreased the pro-inflammatory cytokines in both serum and liver that contribute to a decrease in fatty liver dysfunction. Additionally, polyphenols may improve the regulation of adipokines and prevent hepatic steatosis. According to human clinical studies, polyphenols are promising for NAFLD patients and associated diseases that lead to NAFLD.

CONCLUSION

Preclinical and clinical studies suggest that various polyphenols could prevent steatosis and its progression to non-alcoholic steatohepatitis, as well as ameliorate NAFLD. However, more clinical studies are needed to confirm this hypothesis.

Associations among Dietary Omega-3 Polyunsaturated Fatty Acids, the Gut Microbiota, and Intestinal Immunity

Omega-3 polyunsaturated fatty acids (omega-3 PUFAs), which are essential fatty acids that humans should obtain from diet, have potential benefits for human health. In addition to altering the structure and function of cell membranes, omega-3 PUFAs (docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), alpha-linolenic acid (ALA), and docosapentaenoic acid (DPA)) exert different effects on intestinal immune tolerance and gut microbiota maintenance. Firstly, we review the effect of omega-3 PUFAs on gut microbiota. And the effects of omega-3 PUFAs on intestinal immunity and inflammation were described. Furthermore, the important roles of omega-3 PUFAs in maintaining the balance between gut immunity and the gut microbiota were discussed. Additional factors, such as obesity and diseases (NAFLD, gastrointestinal malignancies or cancer, bacterial and viral infections), which are associated with variability in omega-3 PUFA metabolism, can influence omega-3 PUFAs–microbiome–immune system interactions in the intestinal tract and also play roles in regulating gut immunity. This review identifies several pathways by which the microbiota modulates the gut immune system through omega-3 PUFAs. Omega-3 supplementation can be targeted to specific pathways to prevent and alleviate intestinal diseases, which may help researchers identify innovative diagnostic methods.

Fortifying diet with rapeseed oil instead of butterfat attenuates the progression of diet-induced non-alcoholic fatty liver disease (NAFLD) and impairment of glucose tolerance

BACKGROUND

Absolute dietary fat intake but even more so fatty acid pattern is discussed to be critical in the development of non-alcoholic fatty liver disease (NAFLD). Here, we determined if switching a butterfat enriched diet to a rapeseed oil (RO) enriched diet affects progression of an existing NAFLD and glucose intolerance in mice.

METHODS

For eight weeks, female C57Bl/6J mice were either fed a liquid control (C) or a butterfat-, fructose- and cholesterol-rich diet (BFC, 25E% butterfat) to induce early signs of steatohepatitis and glucose intolerance in mice. For additional five weeks mice received either BFC or C or a fat-, fructose- and cholesterol-rich and control diet, in which butterfat was replaced with RO (ROFC and CRO). Markers of glucose metabolism, liver damage and intestinal barrier were assessed.

RESULTS

Exchanging butterfat with RO attenuated the progression of BFC diet-induced NAFLD and glucose intolerance. Beneficial effects of RO were associated with lower portal endotoxin levels and an attenuation of the induction of the toll-like receptor-4-dependent signaling cascades in liver. Peroxisome proliferator-activated receptor γ activity was induced in small intestine of ROFC-fed mice.

CONCLUSION

Taken together, exchanging butterfat with RO attenuated the progression of diet-induced steatohepatitis and glucose intolerance in mice.

Association of Total Flavonoid Intake with Hypo-HDL-Cholesterolemia among Korean Adults: Effect Modification by Polyunsaturated Fatty Acid Intake

The aim of this study was to examine the independent association between flavonoid intake and hypo-high-density lipoprotein (HDL)-cholesterolemia and the potential modifying effect of polyunsaturated fatty acid (PUFA) intake on this association among Korean adults. This cross-sectional analysis used data from 10,326 subjects who participated in the 2013–2016 Korean National Health and Nutrition Examination Survey. Multiple logistic regression analyses were used to assess the associations of flavonoid and PUFA intakes with hypo-HDL-cholesterolemia prevalence. Proanthocyanidins intake showed an inverse relationship with hypo-HDL-cholesterolemia only in men (Tertile (T) 3 vs. T1: odds ratio (OR) = 0.74, 95% confidence interval (CI) = 0.59–0.92, p-trend = 0.0330). Total flavonoid and PUFA intakes were not associated with hypo-HDL-cholesterolemia in both men and women. However, when stratified by PUFA intake, there was an inverse relationship between total flavonoid intake and hypo-HDL-cholesterolemia prevalence in men with a high n-3 PUFA intake (total flavonoid intakes T3 vs. T1: OR = 0.59, 95% CI = 0.42–0.82, p-trend = 0.0004) or a low n-6/n-3 PUFA intake ratio (T3 vs. T1: OR = 0.67, 95% CI = 0.48–0.93, p-trend = 0.0053), but not in those with a low n-3 PUFA intake (p-interaction = 0.0038) or a high n-6/n-3 PUFA intake ratio (p-interaction = 0.1772). In women, no association was found between total flavonoid intake and hypo-HDL-cholesterolemia, regardless of PUFA intake. These results imply that the intake of proanthocyanidins might have beneficial effects on the HDL-cholesterol level in Korean men. In addition, n-3 PUFA intake might modify the association of total flavonoid intake with the hypo-HDL-cholesterolemia among Korean men.

Functional coix seed protein hydrolysates as a novel agent with potential hepatoprotective effect

The aim of this study is to explore the hepatoprotective potential of coix seed protein hydrolysates (CPP) against alcohol-induced liver injury, and investigate the underlying mechanisms.

Phenyl-γ-valerolactones and phenylvaleric acids, the main colonic metabolites of flavan-3-ols: synthesis, analysis, bioavailability, and bioactivity

Covering: 1958 to June 2018 Phenyl-γ-valerolactones (PVLs) and their related phenylvaleric acids (PVAs) are the main metabolites of flavan-3-ols, the major class of flavonoids in the human diet. Despite their presumed importance, these gut microbiota-derived compounds have, to date, in terms of biological activity, been considered subordinate to their parent dietary compounds, the flavan-3-ol monomers and proanthocyanidins. In this review, the role and prospects of PVLs and PVAs as key metabolites in the understanding of the health features of flavan-3-ols have been critically assessed. Among the topics covered, are proposals for a standardised nomenclature for PVLs and PVAs. The formation, bioavailability and pharmacokinetics of PVLs and PVAs from different types of flavan-3-ols are discussed, taking into account in vitro and animal studies, as well as inter-individual differences and the existence of putative flavan-3-ol metabotypes. Synthetic strategies used for the preparation of PVLs are considered and the methodologies for their identification and quantification assessed. Metabolomic approaches unravelling the role of PVLs and PVAs as biomarkers of intake are also described. Finally, the biological activity of these microbial catabolites in different experimental models is summarised. Knowledge gaps and future research are considered in this key area of dietary (poly)phenol research.

Quantification of Urinary Phenyl-γ-Valerolactones and Related Valeric Acids in Human Urine on Consumption of Apples

Flavan-3-ols are dietary bioactive molecules that have beneficial effects on human health and reduce the risk of various diseases. Monomeric flavan-3-ols are rapidly absorbed in the small intestine and released in the blood stream as phase II conjugates. Polymeric flavan-3-ols are extensively metabolized by colonic gut microbiota into phenyl-γ-valerolactones and their related phenylvaleric acids. These molecules are the main circulating metabolites in humans after the ingestion of flavan-3-ol rich-products; nevertheless, they have received less attention and their role is not understood yet. Here, we describe the quantification of 8 phenyl-γ-valerolactones and 3 phenylvaleric acids in the urine of 11 subjects on consumption of apples by using UHPLC-ESI-Triple Quad-MS with pure reference compounds. Phenyl-γ-valerolactones, mainly as sulfate and glucuronic acid conjugates, reached maximum excretion between 6 and 12 after apple consumption, with a decline thereafter. Significant differences were detected in the cumulative excretion rates within subjects and in the ratio of dihydroxyphenyl-γ-valerolactone sulfate to glucuronide conjugates. This work observed for the first time the presence of two distinct metabotypes with regards to the excretion of phenyl-γ-valerolactone phase II conjugates.

Current Models of Fatty Liver Disease; New Insights, Therapeutic Targets and Interventions

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disorders ranging from simple steatosis to steatosis with inflammation and fibrosis. NAFLD is currently the most prevalent chronic liver disease worldwide, with a global prevalence of 25%, and is soon projected to be the leading cause for liver transplantation in the US. Alarmingly, few effective pharmacotherapeutic approaches are currently available to block or attenuate development and progression of NAFLD. Preclinical models are critical for unraveling the complex and multi-factorial etiology of NAFLD and for testing potential therapeutics. Here we review preclinical models that have been instrumental in highlighting molecular and cellular mechanisms underlying the pathogenesis of NAFLD and in facilitating early proof-of-concept investigations into novel intervention strategies.

Induction of Liver Steatosis in BAP31-Deficient Mice Burdened with Tunicamycin-Induced Endoplasmic Reticulum Stress

Endoplasmic reticulum (ER) stress is highly associated with liver steatosis. B-cell receptor-associated protein 31 (BAP31) has been reported to be involved in ER homeostasis, and plays key roles in hepatic lipid metabolism in high-fat diet-induced obese mice. However, whether BAP31 modulates hepatic lipid metabolism via regulating ER stress is still uncertain. In this study, wild-type and liver-specific BAP31-depleted mice were administrated with ER stress activator of Tunicamycin, the markers of ER stress, liver steatosis, and the underlying molecular mechanisms were determined. BAP31 deficiency increased Tunicamycin-induced hepatic lipid accumulation, aggravated liver dysfunction, and increased the mRNA levels of ER stress markers, including glucose-regulated protein 78 (GRP78), X-box binding protein 1 (XBP1), inositol-requiring protein-1α (IRE1α) and C/EBP homologous protein (CHOP), thus promoting ER stress in vivo and in vitro. Hepatic lipid export via very low-density lipoprotein (VLDL) secretion was impaired in BAP31-depleted mice, accompanied by reduced Apolipoprotein B (APOB) and microsomal triglyceride transfer protein (MTTP) expression. Exogenous lipid clearance was also inhibited, along with impaired gene expression related to fatty acid transportation and fatty acid β-oxidation. Finally, BAP31 deficiency increased Tunicamycin-induced hepatic inflammatory response. These results demonstrate that BAP31 deficiency increased Tunicamycin-induced ER stress, impaired VLDL secretion and exogenous lipid clearance, and reduced fatty acid β-oxidation, which eventually resulted in liver steatosis.

Fructose and sugar: A major mediator of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome; its rising prevalence parallels the rise in obesity and diabetes. Historically thought to result from overnutrition and a sedentary lifestyle, recent evidence suggests that diets high in sugar (from sucrose and/or high-fructose corn syrup [HFCS]) not only increase the risk of NAFLD, but also non-alcoholic steatohepatitis (NASH). Herein, we review the experimental and clinical evidence that fructose precipitates fat accumulation in the liver, due to both increased lipogenesis and impaired fat oxidation. Recent evidence suggests that the predisposition to fatty liver is linked to the metabolism of fructose by fructokinase C, which results in ATP consumption, nucleotide turnover and uric acid generation that mediate fat accumulation. Alterations to gut permeability, the microbiome, and associated endotoxemia contribute to the risk of NAFLD and NASH. Early clinical studies suggest that reducing sugary beverages and total fructose intake, especially from added sugars, may have a significant benefit on reducing hepatic fat accumulation. We suggest larger, more definitive trials to determine if lowering sugar/HFCS intake, and/or blocking uric acid generation, may help reduce NAFLD and its downstream complications of cirrhosis and chronic liver disease.

Rho, a Fraction From Rhodiola crenulate, Ameliorates Hepatic Steatosis in Mice Models

The prevalence of non-alcoholic fatty liver disease (NAFLD), which is developed from hepatic steatosis, is increasing worldwide. However, no specific drugs for NAFLD have been approved yet. To observe the effects of Rho, a fraction from Rhodiola crenulate, on non-alcoholic hepatic steatosis, three mouse models with characteristics of NAFLD were used including high-fat diet (HFD)-induced obesity (DIO) mice, KKAy mice, and HFD combined with tetracycline stimulated Model-T mice. Hepatic lipid accumulation was determined via histopathological analysis and/or hepatic TG determination. The responses to insulin were evaluated by insulin tolerance test (ITT), glucose tolerance test (GTT), and hyperinsulinemic-euglycemic clamp, respectively. The pathways involved in hepatic lipid metabolism were observed via western-blot. Furthermore, the liver microcirculation was observed by inverted microscopy. The HPLC analysis indicated that the main components of Rho were flavan polymers. The results of histopathological analysis showed that Rho could ameliorate hepatic steatosis in DIO, KKAy, and Model-T hepatic steatosis mouse models, respectively. After Rho treatment in DIO mice, insulin resistance was improved with increasing glucose infusion rate (GIR) in hyperinsulinemic-euglycemic clamp, and decreasing areas under the blood glucose-time curve (AUC) in both ITT and GTT; the pathways involved in fatty acid uptake and de novo lipogenesis were both down-regulated, respectively. However, the pathways involved in beta-oxidation and VLDL-export on hepatic steatosis were not changed significantly. The liver microcirculation disturbances were also improved by Rho in DIO mice. These results suggest that Rho is a lead nature product for hepatic steatosis treatment. The mechanism is related to enhancing insulin sensitivity, suppressing fatty acid uptake and inhibiting de novo lipogenesis in liver.