The Role of Fructose in Non-Alcoholic Steatohepatitis: Old Relationship and New Insights

Features, functions, and associated diseases of visceral and ectopic fat: a comprehensive review

Obesity is a complex, chronic, and recurrent disease marked by abnormal or excessive fat accumulation that poses significant health risks. The distribution of body fat, especially ectopic fat deposition, plays a crucial role in the development of chronic metabolic diseases. Under normal conditions, fatty acids are primarily stored in subcutaneous adipose tissue; however, excessive intake can lead to fat accumulation in visceral adipose tissue and ectopic sites, including the pancreas, heart, and muscle. This redistribution is associated with disruptions in energy metabolism, inflammation, and insulin resistance, impairing organ function and raising the risk of cardiovascular disease, diabetes, and fatty liver. This review explores the roles of visceral and ectopic fat in the development of insulin resistance and related diseases such as type 2 diabetes and metabolic dysfunction-associated steatotic liver disease. Specifically, we examine the structure and characteristics of different fat types, their associations with disease, and the underlying pathogenic mechanisms. Future strategies for managing obesity-related diseases may include lifestyle modifications, surgical interventions, and emerging medications that target lipid metabolism and energy regulation, aiming to improve patient outcomes.

Hormone correction of dysfunctional metabolic gene expression in stem cell-derived liver tissue

The increase in metabolic dysfunction-associated steatotic liver disease (MASLD) and its progression to metabolic dysfunction-associated steatohepatitis (MASH) is a worldwide healthcare challenge. Heterogeneity between men and women in the prevalence and mechanisms of MASLD and MASH is related to differential sex hormone signalling within the liver, and declining hormone levels during aging. In this study we used biochemically characterised pluripotent stem cell derived 3D liver spheres to model the protective effects of testosterone and estrogen signalling on metabolic liver disease 'in the dish'. We identified sex steroid-dependent changes in gene expression which were protective against metabolic dysfunction, fibrosis, and advanced cirrhosis patterns of gene expression, providing new insight into the pathogenesis of MASLD and MASH, and highlighting new druggable targets. Additionally, we highlight gene targets for which drugs already exist for future translational studies.

Two-Step Loss of GLUTs in the High-Metabolism Passerines

Glucose transporters (GLUTs) play vital roles in cellular metabolism. Understanding their evolutionary dynamics in birds is essential for elucidating avian physiology and adaptation. However, the choice of gene detection method in gene family analysis may affect the conclusion. Here, we present a comprehensive investigation of methodologies and GLUT gene loss events in avian lineages, focusing on the loss of GLUT4 and GLUT8. To illustrate the effects of these methods, we first employed BUSCO-based homolog identification, calculated pairwise evolutionary distances between different species, and performed separate blastn and blastp searches to identify homologs in two groups of animals. Our analyses revealed a significant decline in blastn accuracy with increasing evolutionary distance, represented by relative divergence times. Through a more robust blastp-based gene detection pipeline, we provide evidence for the loss of GLUT genes in birds based on 58 vertebrate genomes, including 47 bird species. Our results support the reported early loss of GLUT4 in Aves. We also newly emphasize the absence of GLUT8 in passerines, potentially due to adaptation to high-sugar diets in their ancestors. These findings enhance our knowledge of avian metabolism and the evolution of GLUT genes.

Ellagic acid alleviates high-fructose diet-induced non-alcoholic fatty liver disease by modulating liver metabolic profiles and gut microbiota

This study integrated analyses of gut microbiota and metabolomics to investigate the impact of ellagic acid (EA) on non-alcoholic fatty liver disease (NAFLD). Compared to the high-fructose diet (HFruD) group, the EA group exhibited reduced body weight and fat mass, alongside improvements in blood glucose and lipid metabolism. Liver metabolomics analysis revealed that EA increased the abundance of metabolites in pathways related to unsaturated fatty acids, amino acids and bile acids. Furthermore, EA induced alterations in the composition and structure of gut microbiota, notably decreasing bacterial genera enriched by HFruD while promoting beneficial bacteria such as Faecalibaculum. Correlation analysis demonstrated significant associations among NAFLD markers, gut microbiota and liver metabolites influenced by EA. This study provides new insights into the anti-NAFLD effects of EA, suggesting EA as a promising nutraceutical for improving NAFLD.

Fructose catabolism and its metabolic effects: Exploring host-microbiota interactions and the impact of ethnicity

Important health disparities are observed in the prevalence of obesity and associated non-communicable diseases (NCDs), including type 2 diabetes (T2D) and metabolic dysfunction-associated steatotic liver disease (MASLD) among ethnic groups. Yet, the underlying factors accounting for these disparities remain poorly understood. Fructose has been widely proposed as a potential mediator of these NCDs, given that hepatic fructose catabolism can result in deleterious metabolic effects, including insulin resistance and hepatic steatosis. Moreover, the fermentation of fructose by the gut microbiota can produce metabolites such as ethanol and acetate, both which serve as potential substrates for de novo lipogenesis (DNL) and could therefore contribute to the development of these metabolic conditions. Significant inter-ethnic differences in gut microbiota composition have been observed. Moreover, fructose consumption varies across ethnic groups, and fructose intake has been demonstrated to significantly alter gut microbiota composition, which can influence its fermenting properties and metabolic effects. Therefore, ethnic differences in gut microbiota composition, which may be influenced by variations in fructose consumption, could contribute to the observed health disparities. This review provides an overview of the complex interactions between host and microbial fructose catabolism, the role of ethnicity in shaping these metabolic processes and their impact on host health. Understanding these interactions could provide insights into the mechanisms driving ethnic health disparities to improve personalized nutrition strategies. KEY POINTS: Dietary fructose consumption has increased substantially over recent decades, which has been associated with the rising prevalence of obesity and non-communicable diseases (NCDs) such as type 2 diabetes and metabolic dysfunction-associated steatotic liver disease. Pronounced disparities among different ethnic groups in NCD prevalence and dietary fructose consumption underscore the need to elucidate the underlying mechanisms of fructose catabolism and its health effects. Together with the well-known toxic effects of hepatic fructose catabolism, emerging evidence highlights a role for the small intestinal microbiota in fermenting sugars like fructose into various bacterial products with potential deleterious metabolic effects. There are significant ethnic differences in gut microbiota composition that, combined with varying fructose consumption, could mediate the observed health disparities. To comprehensively understand the role of the gut microbiota in mediating fructose-induced adverse metabolic effects, future research should focus on the small intestinal microbiota. Future research on fructose - microbiota - host interactions should account for ethnic differences in dietary habits and microbial composition to elucidate the potential role of the gut microbiota in driving the mentioned health disparities.

Female C57BL/6 mice exhibit protection against nonalcoholic fatty liver disease and diabesity accompanied by differential regulation of hepatic lipocalin prostaglandin D2 synthase

Nonalcoholic fatty liver disease (NAFLD) and its development into nonalcoholic steatohepatitis (NASH) are challenging health concerns globally. Clinically, the prevalence and severity of NAFLD/NASH are higher in men than in premenopausal women. NAFLD is strongly correlated with obesity, both of which are tied to high-fat/fructose-rich western diets. Therefore, we aimed to investigate sexual dimorphism in NAFLD pathogenesis in male and female C57BL/6 mice fed different diets. Male and female C57BL/67 mice were divided into four groups and kept on a chow (C), chow plus high fructose (CF), high fat (HF), and high fat plus high fructose (HFF) diet for 22 weeks. Liver tissues were collected at the end of the study and processed for NAFLD/NASH-related histology (H&E and trichrome staining), protein expression (SREBP1, SCAP, FABP4, α-SMA, TGF-β and L-PGDS), and biochemical parameters measurement. Our results displayed that female mice exhibited protection against NAFLD and diabesity on HF and HFF diets compared to male mice fed similar diets. Additionally, female mice showed protection from fibrosis compared to male mice. Both male and female mice fed HF and HFF diet groups displayed the cytosol-to-nuclear translocation of Lipocalin Prostaglandin D2 Synthase (L-PGDS). Cytoplasmic levels of L-PGDS were absent in females compared to low levels in males, revealing a possible sex-specific mechanism tied to fructose and fat metabolism. Collectively, female mice showed protection against NAFLD and diabesity relative to male mice, accompanied by differential regulation of hepatic lipocalin prostaglandin D2 synthase.

Administration of a probiotic supplement attenuates nonalcoholic fatty liver disease by reducing hepatic lipid accumulation, oxidative stress, and inflammation

Due to the requirement for a novel and effective treatment for non-alcoholic fatty liver disease (NAFLD), this study aimed to determine the effects of a novel supplement containing Lactocaseibacillus zeae and Limosilactobacillus reuteri on oxidative stress, inflammation, glucose and lipid metabolism, lipid accumulation, and liver function in the fructose-induced NAFLD rat model. To investigate the involvement of molecular pathways and validate a preclinical study, NAFLD was induced by feeding them fructose-containing drinking water (20% w/v) for 12 consecutive weeks. The fructose-induced male rats were administered a mixture of L. zeae TISTR 2529 and L. reuteri TISTR 2736 at a dose of 2 × 108 CFU/mL during weeks 0 to 12, daily. Weight and food intake were recorded daily. The production of oxidative stress, expression of the TNF-α, SREBP-1c, liver enzymes, and lipid profiles, including the densities of lipid droplets in liver cells, were also evaluated. The results revealed that fructose-induced rats co-treated with the mixed probiotics had significantly decreased body weights, triglycerides, cholesterol, and liver enzymes. Furthermore, the expression of TNF-α, MDA, and SREBP-1c and the densities of lipid droplets in the liver tissue were reduced. Based on the results, the novel probiotic supplement containing L. zeae TISTR 2529 and L. reuteri TISTR 2736 might alleviate NAFLD by normalizing oxidative stress, inflammation, lipid metabolism, and lipid accumulation in the liver of NAFLD-induced model rats.

Intriguing hepatoprotective effects of sucrose on hepatocellular carcinoma pathogenesis

Chronic liver disease is closely linked to dietary intake factors, such as high consumption of simple carbohydrates including sucrose. In this study, the influence of sucrose on the development of hepatocellular carcinoma (HCC), the most common primary liver malignancy, was explored. Using the hepatocarcinogen diethylnitrosamine (DEN) to induce HCC in the rat, we co-administered sucrose with DEN. The co-administration significantly modified body, liver and pancreas weight, as well as, serum fatty acids and triglycerides. DEN caused liver structural alteration, fibrosis, and tumor formation; surprisingly, co-administration with sucrose restored hepatic lipids, improved liver architecture, and reduced fibrosis and tumor development. Sucrose intake negatively regulated tumor markers and cell proliferation, and reduced the expression of genes associated with lipid metabolism and oxidative stress response. These findings highlight a hepatoprotective effect of sucrose during DEN-induced hepatocarcinogenesis, underlining an intriguing role of high sucrose consumption during HCC development and providing new insights as well as possible pathways of cellular protection under sucrose intake on hepatocarcinogenesis.

The Impact of Fructose Consumption on Human Health: Effects on Obesity, Hyperglycemia, Diabetes, Uric Acid, and Oxidative Stress With a Focus on the Liver

Excessive fructose consumption, primarily through processed foods and beverages, has become a significant public health concern due to its association with various metabolic disorders. This review examines the impact of fructose on human health, focusing on its role in obesity, insulin resistance, hyperglycemia, type 2 diabetes, uric acid production, and oxidative stress. Fructose metabolism, distinct from glucose, predominantly occurs in the liver, where it bypasses normal insulin regulation, leading to increased fat synthesis through de novo lipogenesis. This process contributes to the development of non-alcoholic fatty liver disease and elevates the risk of cardiovascular disease. Furthermore, fructose-induced adenosine triphosphate depletion activates purine degradation, increasing uric acid levels and exacerbating hyperuricemia. The overproduction of reactive oxygen species during fructose metabolism also drives oxidative stress, promoting inflammation and cellular damage. By synthesizing recent findings, this review underscores the importance of regulating fructose intake, implementing public health policies, and adopting lifestyle changes to mitigate these adverse effects.

Fennel seeds extract prevents fructose-induced cardiac dysfunction in a rat model of metabolic syndrome via targeting abdominal obesity, hyperuricemia and NF-κβ inflammatory pathway

BACKGROUND

Metabolic syndrome (MetS) is commonly associated with increased risk of cardiac disease that affects a large number of world populations.

OBJECTIVE

This research attempted to investigate the efficacy of fennel seeds extract (FSE) in preventing development of cardiac dysfunction in rats on fructose enriched diet for 3 months, as a model of MetS.

MATERIALS & METHODS

Thirty adult Wistar male rats (160-170 g) were assigned into 5 groups including control, vehicle, FSE (200 mg/kg BW) and fructose (60%) fed rats with and without FSE. Following the last treatment, blood pressure, ECG and heart rate were measured. Next, blood and cardiac tissues were taken for biochemical and histological investigations.

RESULTS

Feeding fructose exhibited characteristic features of MetS involving, hypertension, abnormal ECG, elevated heart rate, serum glucose, insulin, lipids and insulin resistance, accompanied by abdominal obesity, cardiac hypertrophy and hyperuricemia. Fructose fed rats also showed significant reduction in cardiac antioxidants (GSH, SOD, CAT) with elevation in oxidative stress indices (NADPH oxidase, O2.-, H2O2, MDA, PCO), NF-κβ, pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), adhesion molecules (ICAM-1, VCAM-1) and serum cardiac biomarkers (AST, LDH, CK-MB, cTn-I). Histopathological changes evidenced by destruction of cardiac myofibrils, cytoplasmic vacuolization, and aggregation of inflammatory cells were also detected. Consumption of FSE showed high ability to alleviate fructose-induced hypertension, ECG abnormalities, cardiac hypertrophy, metabolic alterations, oxidative stress, inflammation and histological injury.

CONCLUSION

Findings could suggest FSE as a complementary supplement for preventing MetS and associated cardiac outcomes. However, well controlled clinical studies are still needed.

Effect of short-term moderate intake of ice wine on hepatic glycolipid metabolism in C57BL/6J mice

As the correlation between high fructose intake and metabolism-related diseases (e.g., obesity, fatty liver, and type 2 diabetes) has been increasingly reported, the health benefits of consuming ice wine high in fructose have been called into question. In this study, 6-week-old male C57BL/6J mice were divided into control (pure water), fructose (130 g L-1 fructose solution), alcohol (11% alcohol solution), low-dose (50% diluted ice wine) and high-dose ice wine (100% ice wine) groups to investigate the effects and mechanisms of short-term (4 weeks) ice wine intake on hepatic glycolipid metabolism in mice. The results showed that short-term consumption of ice wine suppressed the elevation of low-density lipoprotein cholesterol content and did not cause hepatic lipid accumulation compared with those of the fructose group. Meanwhile, ice wine had no significant effect on lipogenesis although it inhibited fatty acid oxidation via the PPARα/CPT-1α pathway. Compared with the control group, ice wine interfered with the elevation of fasting glucose and the insulin resistance index in a dose-dependent manner, and led to an increase in plasma uric acid levels, which may further contribute to the disruption of glucolipid metabolism. Overall, short-term moderate intake of ice wine over a 4-week period may not significantly affect hepatic glycolipid metabolism in C57BL/6J mice for the time being.

Association between higher duodenal levels of the fructose carrier glucose transporter-5 and nonalcoholic fatty liver disease and liver fibrosis

BACKGROUND

An increased dietary fructose intake has been shown to exert several detrimental metabolic effects and contribute to the pathogenesis of nonalcoholic fatty liver disease (NAFLD). An augmented intestinal abundance of the fructose carriers glucose transporter-5 (GLUT-5) and glucose transporter-2 (GLUT-2) has been found in subjects with obesity and type 2 diabetes. Herein, we investigated whether elevated intestinal levels of GLUT-5 and GLUT-2, resulting in a higher dietary fructose uptake, are associated with NAFLD and its severity.

METHODS

GLUT-5 and GLUT-2 protein levels were assessed on duodenal mucosa biopsies of 31 subjects divided into 2 groups based on ultrasound-defined NAFLD presence who underwent an upper gastrointestinal endoscopy.

RESULTS

Individuals with NAFLD exhibited increased duodenal GLUT-5 protein levels in comparison to those without NAFLD, independently of demographic and anthropometric confounders. Conversely, no difference in duodenal GLUT-2 abundance was observed amongst the two groups. Univariate correlation analyses showed that GLUT-5 protein levels were positively related with body mass index, waist circumference, fasting and 2 h post-load insulin concentrations, and insulin resistance (IR) degree estimated by homeostatic model assessment of IR (r = 0.44; p = 0.02) and liver IR (r = 0.46; p = 0.03) indexes. Furthermore, a positive relationship was observed between duodenal GLUT-5 abundance and serum uric acid concentrations (r = 0.40; p = 0.05), a product of fructose metabolism implicated in NAFLD progression. Importantly, duodenal levels of GLUT-5 were positively associated with liver fibrosis risk estimated by NAFLD fibrosis score.

CONCLUSION

Increased duodenal GLUT-5 levels are associated with NAFLD and liver fibrosis. Inhibition of intestinal GLUT-5-mediated fructose uptake may represent a strategy for prevention and treatment of NAFLD.

Association of fructose consumption with prevalence of functional gastrointestinal disorders manifestations: results from Hellenic National Nutrition and Health Survey (HNNHS)

The study aimed to assess the total prevalence of functional gastrointestinal disorders (FGID), and separately, irritable bowel syndrome (IBS) among adults and to determine their potential association with fructose consumption. Data from the Hellenic National Nutrition and Health Survey were included (3798 adults; 58·9 % females). Information regarding FGID symptomatology was assessed using self-reported physician diagnosis questionnaires the reliability of which were screened using the ROME III, in a sample of the population. Fructose intake was estimated from 24 h recalls, and the MedDiet score was used to assess adherence to the Mediterranean diet. The prevalence of FGID symptomatology was 20·2 %, while 8·2 % had IBS (representing 40·2 % of total FGID). The likelihood of FGID was 28 % higher (95 %CI: 1·03-1·6) and of IBS 49 % (95 %CI: 1·08-2·05) in individuals with higher fructose intake than with lower intake (3rd tertile compared with 1st). When area of residence was accounted for, individuals residing in the Greek islands had a significantly lower probability of FGID and IBS compared with those residing in Mainland and the main Metropolitan areas, with Islanders also achieving a higher MedDiet score and lower added sugar intake, comparatively to inhabitants of the main metropolitan areas. FGID and IBS symptomatology was most prominent among individuals with higher fructose consumption, and this was most conspicuous in areas with a lower Mediterranean diet adherence, suggesting that the dietary source of fructose rather than total fructose should be examined in relation to FGID.

6-Methyl flavone inhibits Nogo-B expression and improves high fructose diet-induced liver injury in mice

Excessive fructose consumption increases hepatic de novo lipogenesis, resulting in cellular stress, inflammation and liver injury. Nogo-B is a resident protein of the endoplasmic reticulum that regulates its structure and function. Hepatic Nogo-B is a key protein in glycolipid metabolism, and inhibition of Nogo-B has protective effects against metabolic syndrome, thus small molecules that inhibit Nogo-B have therapeutic benefits for glycolipid metabolism disorders. In this study we tested 14 flavones/isoflavones in hepatocytes using dual luciferase reporter system based on the Nogo-B transcriptional response system, and found that 6-methyl flavone (6-MF) exerted the strongest inhibition on Nogo-B expression in hepatocytes with an IC50 value of 15.85 μM. Administration of 6-MF (50 mg· kg-1 ·d-1, i.g. for 3 weeks) significantly improved insulin resistance along with ameliorated liver injury and hypertriglyceridemia in high fructose diet-fed mice. In HepG2 cells cultured in a media containing an FA-fructose mixture, 6-MF (15 μM) significantly inhibited lipid synthesis, oxidative stress and inflammatory responses. Furthermore, we revealed that 6-MF inhibited Nogo-B/ChREBP-mediated fatty acid synthesis and reduced lipid accumulation in hepatocytes by restoring cellular autophagy and promoting fatty acid oxidation via the AMPKα-mTOR pathway. Thus, 6-MF may serve as a potential Nogo-B inhibitor to treat metabolic syndrome caused by glycolipid metabolism dysregulation.

The Impact and Burden of Dietary Sugars on the Liver

NAFLD, or metabolic dysfunction-associated steatotic liver disease, has increased in prevalence hand in hand with the rise in obesity and increased free sugars in the food supply. The causes of NAFLD are genetic in origin combined with environmental drivers of the disease phenotype. Dietary intake of added sugars has been shown to have a major role in the phenotypic onset and progression of the disease. Simple sugars are key drivers of steatosis, likely through fueling de novo lipogenesis, the conversion of excess carbohydrates into fatty acids, but also appear to upregulate lipogenic metabolism and trigger hyperinsulinemia, another driver. NAFLD carries a clinical burden as it is associated with obesity, type 2 diabetes, metabolic syndrome, and cardiovascular disease. Patient quality of life is also impacted, and there is an enormous economic burden due to healthcare use, which is likely to increase in the coming years. This review aims to discuss the role of dietary sugar in NAFLD pathogenesis, the health and economic burden, and the promising potential of sugar reduction to improve health outcomes for patients with this chronic liver disease.

Acetyl-11-Keto-Beta-Boswellic Acid Has Therapeutic Benefits for NAFLD Rat Models That Were Given a High Fructose Diet by Ameliorating Hepatic Inflammation and Lipid Metabolism

Acetyl-11-keto-beta-boswellic acid (AKBA), a potent anti-inflammatory compound purified from Boswellia species, was investigated in a preclinical study for its potential in preventing and treating non-alcoholic fatty liver disease (NAFLD), the most common chronic inflammatory liver disorder. The study involved thirty-six male Wistar rats, equally divided into prevention and treatment groups. In the prevention group, rats were given a high fructose diet (HFrD) and treated with AKBA for 6 weeks, while in the treatment group, rats were fed HFrD for 6 weeks and then given a normal diet with AKBA for 2 weeks. At the end of the study, various parameters were analyzed including liver tissues and serum levels of insulin, leptin, adiponectin, monocyte chemoattractant protein-1 (MCP-1), transforming growth factor beta (TGF-β), interferon gamma (INF-ϒ), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α). Additionally, the expression levels of genes related to the inflammasome complex and peroxisome proliferator-activated receptor gamma (PPAR-ϒ), as well as the levels of phosphorylated and non-phosphorylated AMP-activated protein kinase alpha-1 (AMPK-α1) protein, were measured. The results showed that AKBA improved NAFLD-related serum parameters and inflammatory markers and suppressed PPAR-ϒ and inflammasome complex-related genes involved in hepatic steatosis in both groups. Additionally, AKBA prevented the reduction of the active and inactive forms of AMPK-α1 in the prevention group, which is a cellular energy regulator that helps suppress NAFLD progression. In conclusion, AKBA has a beneficial effect on preventing and avoiding the progression of NAFLD by preserving lipid metabolism, improving hepatic steatosis, and suppressing liver inflammation.

The intestinal-hepatic axis: a comprehensive review on fructose metabolism and its association with mortality and chronic metabolic diseases

Fructose is a common ingredient of food industry in the form of sucrose and high fructose corn sirup (HFCS). Due to its unique metabolic properties, excessive intake of fructose has been linked to various diseases, including obesity, nonalcoholic fatty liver disease (NAFLD), cardiovascular disease (CVD), chronic renal insufficiency, and even increase the risk of death. Interestingly, although high fructose intake may induce gout, it does not cause hyperuricemia, and the underlying molecular mechanisms remain debated. While previous studies focused on the liver as the primary site of fructose metabolism, recent evidence has suggested a crucial role for the intestine-hepatic axis in fructose metabolism. Low dose fructose is mainly metabolized in the small intestine. Only when the intake exceeds the intestine's metabolic capacity fructose spills over to be metabolized in the liver. High fructose diets also have a significant impact on the diversity of the gut microbiota, leading to alterations in the metabolic byproducts produced by these gut bacteria and thereby inducing endotoxemia. This paper provides a comprehensive review of the epidemiological and pathological studies conducted in recent years, describing the metabolic differences between fructose and glucose and the possible mechanisms underlying the link between excessive fructose intake and chronic metabolic diseases.

CD38 Inhibition Protects Fructose-Induced Toxicity in Primary Hepatocytes

A fructose-enriched diet is thought to contribute to hepatic injury in developing non-alcoholic steatohepatitis (NASH). However, the cellular mechanism of fructose-induced hepatic damage remains poorly understood. This study aimed to determine whether fructose induces cell death in primary hepatocytes, and if so, to establish the underlying cellular mechanisms. Our results revealed that treatment with high fructose concentrations for 48 h induced mitochondria-mediated apoptotic death in mouse primary hepatocytes (MPHs). Endoplasmic reticulum stress responses were involved in fructose-induced death as the levels of phosho-eIF2α, phospho-C-Jun-N-terminal kinase (JNK), and C/EBP homologous protein (CHOP) increased, and a chemical chaperone tauroursodeoxycholic acid (TUDCA) prevented cell death. The impaired oxidation metabolism of fatty acids was also possibly involved in the fructose-induced toxicity as treatment with an AMP-activated kinase (AMPK) activator and a PPAR-α agonist significantly protected against fructose-induced death, while carnitine palmitoyl transferase I inhibitor exacerbated the toxicity. However, uric acid-mediated toxicity was not involved in fructose-induced death as uric acid was not toxic to MPHs, and the inhibition of xanthine oxidase (a key enzyme in uric acid synthesis) did not affect cell death. On the other hand, treatment with inhibitors of the nicotinamide adenine dinucleotide (NAD)+-consuming enzyme CD38 or CD38 gene knockdown significantly protected against fructose-induced toxicity in MPHs, and fructose treatment increased CD38 levels. These data suggest that CD38 upregulation plays a role in hepatic injury in the fructose-enriched diet-mediated NASH. Thus, CD38 inhibition may be a promising therapeutic strategy to prevent fructose-enriched diet-mediated NASH.

High Fructose Causes More Prominent Liver Steatohepatitis with Leaky Gut Similar to High Glucose Administration in Mice and Attenuation by Lactiplantibacillus plantarum dfa1

High-sugar diet-induced prediabetes and obesity are a global current problem that can be the result of glucose or fructose. However, a head-to-head comparison between both sugars on health impact is still lacking, and Lactiplantibacillus plantarum dfa1 has never been tested, and has recently been isolated from healthy volunteers. The mice were administered with the high glucose or fructose preparation in standard mouse chaw with or without L. plantarum dfa1 gavage, on alternate days, and in vitro experiments were performed using enterocyte cell lines (Caco2) and hepatocytes (HepG2). After 12 weeks of experiments, both glucose and fructose induced a similar severity of obesity (weight gain, lipid profiles, and fat deposition at several sites) and prediabetes condition (fasting glucose, insulin, oral glucose tolerance test, and Homeostatic Model Assessment for Insulin Resistance (HOMA score)). However, fructose administration induced more severe liver damage (serum alanine transaminase, liver weight, histology score, fat components, and oxidative stress) than the glucose group, while glucose caused more prominent intestinal permeability damage (FITC-dextran assay) and serum cytokines (TNF-α, IL-6, and IL-10) compared to the fructose group. Interestingly, all of these parameters were attenuated by L. plantarum dfa1 administration. Because there was a subtle change in the analysis of the fecal microbiome of mice with glucose or fructose administration compared to control mice, the probiotics altered only some microbiome parameters (Chao1 and Lactobacilli abundance). For in vitro experiments, glucose induced more damage to high-dose lipopolysaccharide (LPS) (1 µg/mL) to enterocytes (Caco2 cell) than fructose, as indicated by transepithelial electrical resistance (TEER), supernatant cytokines (TNF-α and IL-8), and glycolysis capacity (by extracellular flux analysis). Meanwhile, both glucose and fructose similarly facilitated LPS injury in hepatocytes (HepG2 cell) as evaluated by supernatant cytokines (TNF-α, IL-6, and IL-10) and extracellular flux analysis. In conclusion, glucose possibly induced a more severe intestinal injury (perhaps due to LPS-glucose synergy) and fructose caused a more prominent liver injury (possibly due to liver fructose metabolism), despite a similar effect on obesity and prediabetes. Prevention of obesity and prediabetes with probiotics was encouraged.

High-Fructose Diet-Induced Hyperuricemia Accompanying Metabolic Syndrome-Mechanisms and Dietary Therapy Proposals

Fructose is often used as a food ingredient due to its low production costs and sweetening power. In recent years, it has been noticed that people on a Western diet high in fructose have high levels of uric acid in their blood. It was recognized that the specific metabolism of fructose in the body might cause increased production of uric acid, which then may affect the intensification of lipogenesis and the development of metabolic syndrome (MetS), insulin resistance, gout, cardiovascular diseases, leptin resistance, or non-alcoholic fatty liver disease. So far, to treat hyperuricemia, it has been recommended to use a low-purine diet characterized by limiting protein-containing products. However, this recommendation often leads to an increased intake of carbohydrate-rich foods that may contain fructose. Increased fructose consumption may enhance the secretion of uric acid again and, consequently, does not have therapeutic effects. Therefore, instead of a low-purine diet, using healthy diets, such as DASH or the Mediterranean diet, which can benefit metabolic parameters, could be a better proposal. This article provides an overview of this approach, focusing on MetS and hyperuricemia among high-fructose dieters.

Treating inflammation to combat non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) with its more progressive form non-alcoholic steatohepatitis (NASH) has become the most common chronic liver disease, thereby representing a great burden for patients and healthcare systems. Specific pharmacological therapies for NAFLD are still missing. Inflammation is an important driver in the pathogenesis of NASH, and the mechanisms underlying inflammation in NAFLD represent possible therapeutic targets. In NASH, various intra- and extrahepatic triggers involved in the metabolic injury typically lead to the activation of different immune cells. This includes hepatic Kupffer cells, i.e. liver-resident macrophages, which can adopt an inflammatory phenotype and activate other immune cells by releasing inflammatory cytokines. As inflammation progresses, Kupffer cells are increasingly replaced by monocyte-derived macrophages with a distinct lipid-associated and scar-associated phenotype. Many other immune cells, including neutrophils, T lymphocytes - such as auto-aggressive cytotoxic as well as regulatory T cells - and innate lymphoid cells balance the progression and regression of inflammation and subsequent fibrosis. The detailed understanding of inflammatory cell subsets and their activation pathways prompted preclinical and clinical exploration of potential targets in NAFLD/NASH. These approaches to target inflammation in NASH include inhibition of immune cell recruitment via chemokine receptors (e.g. cenicriviroc), neutralization of CD44 or galectin-3 as well as agonism to nuclear factors like peroxisome proliferator-activated receptors and farnesoid X receptor that interfere with the activation of immune cells. As some of these approaches did not demonstrate convincing efficacy as monotherapies, a rational and personalized combination of therapeutic interventions may be needed for the near future.

A Comparison of Primary Human Hepatocytes and Hepatoma Cell Lines to Model the Effects of Fatty Acids, Fructose and Glucose on Liver Cell Lipid Accumulation

Non-alcoholic fatty liver disease (NAFLD) begins with lipid accumulation within hepatocytes, but the relative contributions of different macronutrients is still unclear. We investigated the impact of fatty acids, glucose and fructose on lipid accumulation in primary human hepatocytes (PHH) and three different cell lines: HepG2 (human hepatoblastoma−derived cell line), Huh7 (human hepatocellular carcinoma cell line) and McA-RH7777 (McA, rat hepatocellular carcinoma cell line). Cells were treated for 48 h with fatty acids (0 or 200 μM), glucose (5 mM or 11 mM) and fructose (0 mM, 2 mM or 8 mM). Lipid accumulation was measured via Nile Red staining. All cell types accumulated lipid in response to fatty acids (p < 0.001). PHH and McA, but not HepG2 or Huh7 cells, accumulated more lipid with 11 mM glucose plus fatty acids (p = 0.004, fatty acid × glucose interaction, for both), but only PHH increased lipid accumulation in response to fructose (p < 0.001). Considerable variation was observed between PHH cells from different individuals. Lipid accumulation in PHH was increased by insulin (p = 0.003) with inter-individual variability. Similarly, insulin increased lipid accumulation in both HepG2 and McA cells, with a bigger response in McA in the presence of fatty acids (p < 0.001 for fatty acid × insulin). McA were more insulin sensitive than either HepG2 or Huh7 cells in terms of AKT phosphorylation (p < 0.001 insulin × cell type interaction). Hence, glucose and fructose can contribute to the accumulation of lipid in PHH with considerable inter-individual variation, but hepatoma cell lines are not good models of PHH.

Naringin attenuates fructose-induced NAFLD progression in rats through reducing endogenous triglyceride synthesis and activating the Nrf2/HO-1 pathway

Background: Excessive fructose consumption causes hepatic lipid accumulation via increased triglyceride (TG) synthesis, leading to the development and progression of non-alcoholic fatty liver disease (NALFD). Naringin, a flavanone glycoside found in citrus fruit, has antioxidant and hypolipidemic properties. Therefore, the aim of this study was to investigate the effect of naringin on fructose-induced NAFLD in rats and the possible underlying mechanism. Methods: Male Sprague Dawley rats were given 10% (w/v) fructose in drinking water for 12 weeks. Naringin (100 mg/kg/day) was administered orally to rats for the last 4 weeks of fructose overload. After 12 weeks of treatment, the hepatic lipid content was determined. In addition, the expression of proteins involved in de novo lipogenesis (DNL) and TG synthesis as well as antioxidant and inflammatory mediators in the liver were examined by western blot analysis. Results: Treatment of fructose-fed rats with naringin significantly decreased the hepatic TG and cholesterol content as well as serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities. Naringin treatment also decreased the hepatic expression of carbohydrate response element binding protein (ChREBP), sterol regulatory element-binding protein-1c (SREBP-1c) and nuclear SREBP-1c (nSREBP-1c) as well as enzymes involved in DNL (acetyl CoA carboxylase [ACC] and fatty acid synthase [FAS]) and an enzyme involved in TG synthesis (glycerol-3-phosphate acyltransferase 1 [GPAT-1] and diacylglycerol acyltransferase2 [DGAT2]) in fructose-fed rats. In addition, naringin induced a significant decrease in the hepatic expression of nuclear factor kappa B (NF-κB) and tumor necrosis factor α (TNF-α). Furthermore, naringin administration restored the expression of the antioxidant mediators nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1) in the liver of fructose-fed rats. Conclusion: These results demonstrate that oral administration of naringin protects against fructose-induced hepatic steatosis by decreasing DNL and TG synthesis. In addition, naringin could prevent NAFLD progression via targeting the Nrf2/HO-1 and the NF-κB/TNF-α pathways.

Dietary Polyphenols and In Vitro Intestinal Fructose Uptake and Transport: A Systematic Literature Review

Recent evidence links chronic consumption of large amounts of fructose (FRU) with several non-communicable disease. After ingestion, dietary FRU is absorbed into the intestinal tract by glucose transporter (GLUT) 5 and transported to the portal vein via GLUT2. GLUT2 is primarily localized on the basolateral membrane, but GLUT2 may be dislocated post-prandially from the basolateral membrane of intestinal cells to the apical one. Polyphenols (PP) are plant secondary metabolites that exert hypoglycemic properties by modulating intracellular insulin signaling pathways and by inhibiting intestinal enzymes and transporters. Post-prandially, PP may reach high concentrations in the gut lumen, making the inhibition of FRU absorption a prime target for exploring the effects of PP on FRU metabolism. Herein, we have systematically reviewed studies on the effect of PP and PP-rich products on FRU uptake and transport in intestinal cells. In spite of expectations, the very different experimental conditions in the various individual studies do not allow definitive conclusions to be drawn. Future investigations should rely on standardized conditions in order to obtain comparable results that allow a credible rating of polyphenols and polyphenol-rich products as inhibitors of fructose uptake.

β-Hydroxyphosphocarnitine modifies fibrosis, steatosis and improves liver function in non-alcoholic steatohepatitis induced in rats

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is a chronic disease characterized by inflammation, steatosis, and liver fibrosis. The liver is particularly affected by alterations in lipid metabolism. Our aim was to evaluate the effect of β-hydroxyphosphocarnitine (β-HPC) on NASH induced in rats.

METHODS

NASH was produced via the ad libitum daily chronic administration of a fructose solution (400 kcal) for 9 weeks, an oral dose of fat solution (16 kcal) for 7 weeks and a subcutaneous injection of CCl4 (30%) two times a week for 2 weeks to Wistar rats. To evaluate the effect of β-HPC, a dose of 100 mg/kg was administered perorally for 4 weeks and its biochemical and hepatic effects on rats with NASH were analyzed. Serum levels of glucose, triglycerides, cholesterol, and liver enzymes were quantified. Histological changes were evaluated on slices stained with H&E, trichromic and PAS. Glycogen content was measured in liver samples. α-SMA and SREBP-1 immunopositive cells were identified in liver tissue.

RESULTS

NASH was characterized by elevated triglycerides, elevated liver damage enzymes, and the presence of necrosis, inflammation, steatosis, and fibrosis. Significant amounts of glycogen were found, along with α-SMA positive cells in fibrosis areas. The over-expression of SREBP-1 in cytoplasm and nuclei was evident. Animals with NASH treated with β-HPC showed a significant reduction in inflammation, necrosis, and glycogen content in the liver. A reduction in α-SMA and SREBP-1 immunopositive cells correlated with a significant reduction in the degree of fibrosis and steatosis found in liver tissue. β-HPC reduced the levels of ALP and GGT, and significantly reduced triglyceride levels. Animals treated with β-HPC did not show any alterations in liver enzyme function.

CONCLUSIONS

Our research shows that β-HPC can improve liver function and morphology in the case of NASH induced in rats, suggesting β-HPC could be potentially used in the treatment of NASH.

Nonalcoholic steatohepatitis and mechanisms by which it is ameliorated by activation of the CNC-bZIP transcription factor Nrf2

Non-alcoholic steatohepatitis (NASH) represents a global health concern. It is characterised by fatty liver, hepatocyte cell death and inflammation, which are associated with lipotoxicity, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, iron overload and oxidative stress. NF-E2 p45-related factor 2 (Nrf2) is a transcription factor that combats oxidative stress. Remarkably, Nrf2 is downregulated during the development of NASH, which probably accelerates disease, whereas in pre-clinical studies the upregulation of Nrf2 inhibits NASH. We now review the scientific literature that proposes Nrf2 downregulation during NASH involves its increased ubiquitylation and proteasomal degradation, mediated by Kelch-like ECH-associated protein 1 (Keap1) and/or β-transducin repeat-containing protein (β-TrCP) and/or HMG-CoA reductase degradation protein 1 (Hrd1, also called synoviolin (SYVN1)). Additionally, downregulation of Nrf2-mediated transcription during NASH may involve diminished recruitment of coactivators by Nrf2, due to increased levels of activating transcription factor 3 (ATF3) and nuclear factor-kappaB (NF-κB) p65, or competition for promoter binding due to upregulation of BTB and CNC homology 1 (Bach1). Many processes that downregulate Nrf2 are triggered by transforming growth factor-beta (TGF-β), with oxidative stress amplifying its signalling. Oxidative stress may also increase suppression of Nrf2 by β-TrCP through facilitating formation of the DSGIS-containing phosphodegron in Nrf2 by glycogen synthase kinase-3. In animal models, knockout of Nrf2 increases susceptibility to NASH, while pharmacological activation of Nrf2 by inducing agents that target Keap1 inhibits development of NASH. These inducing agents probably counter Nrf2 downregulation affected by β-TrCP, Hrd1/SYVN1, ATF3, NF-κB p65 and Bach1, by suppressing oxidative stress. Activation of Nrf2 is also likely to inhibit NASH by ameliorating lipotoxicity, inflammation, ER stress and iron overload. Crucially, pharmacological activation of Nrf2 in mice in which NASH has already been established supresses liver steatosis and inflammation. There is therefore compelling evidence that pharmacological activation of Nrf2 provides a comprehensive multipronged strategy to treat NASH.

Endocrine and Metabolic Impact of Oral Ingestion of a Carob-Pod-Derived Natural-Syrup-Containing D-Pinitol: Potential Use as a Novel Sweetener in Diabetes

The widespread use of added sugars or non-nutritive sweeteners in processed foods is a challenge for addressing the therapeutics of obesity and diabetes. Both types of sweeteners generate health problems, and both are being blamed for multiple complications associated with these prevalent diseases. As an example, fructose is proven to contribute to obesity and liver steatosis, while non-nutritive sweeteners generate gut dysbiosis that complicates the metabolic control exerted by the liver. The present work explores an alternative approach for sweetening through the use of a simple carob-pod-derived syrup. This sweetener consists of a balanced mixture of fructose (47%) and glucose (45%), as sweetening sugars, and a functional natural ingredient (D-Pinitol) at a concentration (3%) capable of producing active metabolic effects. The administration of this syrup to healthy volunteers (50 g of total carbohydrates) resulted in less persistent glucose excursions, a lower insulin response to the hyperglycemia produced by its ingestion, and an enhanced glucagon/insulin ratio, compared to that observed after the ingestion of 50 g of glucose. Daily administration of the syrup to Wistar rats for 10 days lowered fat depots in the liver, reduced liver glycogen, promoted fat oxidation, and was devoid of toxic effects. In addition, this repeated administration of the syrup improved glucose handling after a glucose (2 g/kg) load. Overall, this alternative functional sweetener retains the natural palatability of a glucose/fructose syrup while displaying beneficial metabolic effects that might serve to protect against the progression towards complicated obesity, especially the development of liver steatosis.

Fructose metabolism and its role in pig production: A mini-review

Epidemiological studies have shown that excessive intake of fructose is largely responsible for the increasing incidence of non-alcoholic fatty liver, obesity, and diabetes. However, depending on the amount of fructose consumption from diet, the metabolic role of fructose is controversial. Recently, there have been increasing studies reporting that diets low in fructose expand the surface area of the gut and increase nutrient absorption in mouse model, which is widely used in fructose-related studies. However, excessive fructose consumption spills over from the small intestine into the liver for steatosis and increases the risk of colon cancer. Therefore, suitable animal models may be needed to study fructose-induced metabolic changes. Along with its use in global meat production, pig is well-known as a biomedical model with an advantage over murine and other animal models as it has similar nutrition and metabolism to human in anatomical and physiological aspects. Here, we review the characteristics and metabolism of fructose and summarize observations of fructose in pig reproduction, growth, and development as well as acting as a human biomedical model. This review highlights fructose metabolism from the intestine to the blood cycle and presents the critical role of fructose in pig, which could provide new strategies for curbing human metabolic diseases and promoting pig production.

Maternal high-fat diet aggravates fructose-induced mitochondrial damage in skeletal muscles and causes differentiated adaptive responses on lipid metabolism in adult male offspring

Maternal high-fat diet (HFD) is associated with metabolic disturbances in the offspring. Fructose is a highly consumed lipogenic sugar; however, it is unknown whether skeletal muscle of maternal HFD offspring respond differentially to a fructose overload. Female Wistar rats received standard diet (STD: 9% fat) or isocaloric high-fat diet (HFD: 29% fat) during 8 weeks before mating until weaning. After weaning, male offspring received STD and, from 120 to 150 days-old, they drank water or 15% fructose in water (STD-F and HFD-F). At 150th day, we collected the oxidative soleus and glycolytic extensor digitorum longus (EDL) muscles. Fructose-treated groups exhibited hypertriglyceridemia, regardless of maternal diet. Soleus of maternal HFD offspring showed increased triglycerides and monounsaturated fatty acid content, independent of fructose, with increased fatty acid transporters and lipogenesis markers. The EDL exhibited unaltered triglycerides content, with an apparent equilibrium between lipogenesis and lipid oxidation markers in HFD, and higher lipid uptake (fatty acid-binding protein 4) accompanied by enhanced monounsaturated fatty acid in fructose-treated groups. Mitochondrial complexes proteins and Tfam mRNA were increased in the soleus of HFD, while uncoupling protein 3 was decreased markedly in HFD-F. In EDL, maternal HFD increased ATP synthase, while fructose decreased Tfam predominantly in STD offspring. Maternal HFD and fructose induced mitochondria ultrastructural damage, intensified in HFD-F in both muscles. Thus, alterations in molecular markers of lipid metabolism and mitochondrial function in response to fructose are modified by an isocaloric and moderate maternal HFD and are fiber-type specific, representing adaptation/maladaptation mechanisms associated with higher skeletal muscle fructose-induced mitochondria injury in adult offspring.

Maternal Isocaloric High-Fat Diet Induces Liver Mitochondria Maladaptations and Homeostatic Disturbances Intensifying Mitochondria Damage in Response to Fructose Intake in Adult Male Rat Offspring

SCOPE

Perinatal maternal obesity and excessive fructose consumption have been associated with liver metabolic diseases. We investigated whether moderate maternal high-fat diet affects the liver mitochondria responses to fructose intake in adult offspring.

METHODS AND RESULTS

Wistar female rats received a standard diet (mSTD) or high-fat diet (mHFD) (9% and 28.6% fat, respectively), before mating until the end of lactation. Male offspring were fed standard diet from weaning to adulthood and received water or fructose-drinking water (15%) from 120 to 150 days old. Fructose induced liver mitochondrial ultrastructural alterations with higher intensity in mHFD offspring, accompanied by reduced autophagy markers. Isolated mitochondria respirometry showed unaltered ATP-coupled oxygen consumption with increased Atp5f1b mRNA only in mHFD offspring. Fructose increased basal respiration and encoding complex I-III mRNA, only in mSTD offspring. Uncoupled respiration was lower in mHFD mitochondria that were unable to exhibit fructose-induced increase Ucp2 mRNA. Fructose decreased antioxidative defense markers, increased unfolded protein response and insulin resistance only in mHFD offspring without fructose-induced hepatic lipid accumulation.

CONCLUSION

Mitochondrial dysfunction and homeostatic disturbances in response to fructose are early events evidencing the higher risk of fructose damage in the liver of adult offspring from dams fed an isocaloric moderate high-fat diet. This article is protected by copyright. All rights reserved.

An Assessment of the Nutritional Value of the Preschool Food Rations for Children from the Wroclaw District, Poland—The Case of a Big City

The evaluation of nutrition is an essential element of preventing chronic diseases and can be used to determine nutritional recommendations. A child spends about 7–8 h a day in a kindergarten; therefore, meals served there should be balanced appropriately to ensure the full psychophysical development of the young organism. At preschool age, children develop eating habits that can have life-long effects. Based on 10-day menus, the study aimed to estimate the energy and nutritional value of children’s diets at four randomly selected kindergartens in the Wroclaw district, Poland. In total, 80 menus were analyzed (40 for summer and 40 for autumn). The data from kindergartens were analyzed based on the Diet 6D computer program. Regardless of the kindergarten, the analyzed food rations showed irregularities related to excessive supplies (in reference to the dietary recommendations) of sucrose, fiber, salt, magnesium, and vitamin A. The preschool food rations did not cover demands with respect to PUFA n-3, PUFA-n-6, calcium, and vitamin D. The observed irregularities confirm the need to monitor the content of energy and nutrients in preschool menus to be able to correct any dietary errors.

Non-Alcoholic Steatohepatitis (NASH) and Organokines: What Is Now and What Will Be in the Future

Non-alcoholic steatohepatitis (NASH) is characterized by steatosis, lobular inflammation, and enlargement of the diameter of hepatocytes (ballooning hepatocytes), with or without fibrosis. It affects 20% of patients with non-alcoholic fatty liver disease (NAFLD). Due to liver dysfunction and the numerous metabolic changes that commonly accompany the condition (obesity, insulin resistance, type 2 diabetes, and metabolic syndrome), the secretion of organokines is modified, which may contribute to the pathogenesis or progression of the disease. In this sense, this study aimed to perform a review of the role of organokines in NASH. Thus, by combining descriptors such as NASH, organokines, oxidative stress, inflammation, insulin resistance, and dyslipidemia, a search was carried out in the EMBASE, MEDLINE-PubMed, and Cochrane databases of articles published in the last ten years. Insulin resistance, inflammation and mitochondrial dysfunction, fructose, and intestinal microbiota were factors identified as participating in the genesis and progression of NASH. Changes in the pattern of organokines secretion (adipokines, myokines, hepatokines, and osteokines) directly or indirectly contribute to aggravating the condition or compromise homeostasis. Thus, further studies involving skeletal muscle, adipose, bone, and liver tissue as endocrine organs are essential to better understand the modulation of organokines involved in the pathogenesis of NASH to advance in the treatment of this disease.

Oenothein B in Eucalyptus Leaf Extract Suppresses Fructose Absorption in Caco-2 Cells

Inhibition of fructose absorption may suppress adiposity and adiposity-related diseases caused by fructose ingestion. Eucalyptus leaf extract (ELE) inhibits intestinal fructose absorption (but not glucose absorption); however, its active compound has not yet been identified. Therefore, we evaluated the inhibitory activity of ELE obtained from Eucalyptus globulus using an intestinal fructose permeation assay with the human intestinal epithelial cell line Caco-2. The luminal sides of a cell monolayer model cultured on membrane filters were exposed to fructose with or without the ELE. Cellular fructose permeation was evaluated by measuring the fructose concentration in the medium on the basolateral side. ELE inhibited 65% of fructose absorption at a final concentration of 1 mg/mL. Oenothein B isolated from the ELE strongly inhibited fructose absorption; the inhibition rate was 63% at a final concentration of 5 μg/mL. Oenothein B did not affect glucose absorption. In contrast, the other major constituents (i.e., gallic acid and ellagic acid) showed little fructose-inhibitory activity. To our knowledge, this is the first report that oenothein B in ELE strongly inhibits fructose absorption in vitro. ELE containing oenothein B can prevent and ameliorate obesity and other diseases caused by dietary fructose consumption.

Pathophysiological Mechanisms in Non-Alcoholic Fatty Liver Disease: From Drivers to Targets

Non-alcoholic fatty liver disease (NAFLD) is characterized by the excessive and detrimental accumulation of liver fat as a result of high-caloric intake and/or cellular and molecular abnormalities. The prevalence of this pathological event is increasing worldwide, and is intimately associated with obesity and type 2 diabetes mellitus, among other comorbidities. To date, only therapeutic strategies based on lifestyle changes have exhibited a beneficial impact on patients with NAFLD, but unfortunately this approach is often difficult to implement, and shows poor long-term adherence. For this reason, great efforts are being made to elucidate and integrate the underlying pathological molecular mechanism, and to identify novel and promising druggable targets for therapy. In this regard, a large number of clinical trials testing different potential compounds have been performed, albeit with no conclusive results yet. Importantly, many other clinical trials are currently underway with results expected in the near future. Here, we summarize the key aspects of NAFLD pathogenesis and therapeutic targets in this frequent disorder, highlighting the most recent advances in the field and future research directions.

Inflammation and Fibrogenesis in MAFLD: Role of the Hepatic Immune System

Metabolic (dysfunction)-associated fatty liver disease (MAFLD) is the definition recently proposed to better circumscribe the spectrum of conditions long known as non-alcoholic fatty liver disease (NAFLD) that range from simple steatosis without inflammation to more advanced liver diseases. The progression of MAFLD, as well as other chronic liver diseases, toward cirrhosis, is driven by hepatic inflammation and fibrogenesis. The latter, result of a "chronic wound healing reaction," is a dynamic process, and the understanding of its underlying pathophysiological events has increased in recent years. Fibrosis progresses in a microenvironment where it takes part an interplay between fibrogenic cells and many other elements, including some cells of the immune system with an underexplored or still unclear role in liver diseases. Some therapeutic approaches, also acting on the immune system, have been probed over time to evaluate their ability to improve inflammation and fibrosis in NAFLD, but to date no drug has been approved to treat this condition. In this review, we will focus on the contribution of the liver immune system in the progression of NAFLD, and on therapies under study that aim to counter the immune substrate of the disease.

Why may citrate sodium significantly increase the effectiveness of transarterial chemoembolization in hepatocellular carcinoma?

Hepatocellular carcinoma (HCC) represents the third cause of cancer death in men worldwide, and its increasing incidence can be explained by the increasing occurrence of non-alcoholic steatohepatitis (NASH). HCC prognosis is poor, as its 5-year overall survival is approximately 18 % and most cases are diagnosed at an inoperable advanced stage. Moreover, tumor sensitivity to conventional chemotherapeutics (particularly to cisplatin-based regimen), trans-arterial chemoembolization (cTACE), tyrosine kinase inhibitors, anti-angiogenic molecules and immune checkpoint inhibitors is limited. Oncogenic signaling pathways, such as HIF-1α and RAS/PI3K/AKT, may provoke drug resistance by enhancing the aerobic glycolysis ("Warburg effect") in cancer cells. Indeed, this metabolism, which promotes cancer cell development and aggressiveness, also induces extracellular acidity. In turn, this acidity promotes the protonation of drugs, hence abrogating their internalization, since they are most often weakly basic molecules. Consequently, targeting the Warburg effect in these cancer cells (which in turn would reduce the extracellular acidification) could be an effective strategy to increase the delivery of drugs into the tumor. Phosphofructokinase-1 (PFK1) and its activator PFK2 are the main regulators of glycolysis, and they also couple the enhancement of glycolysis to the activation of key signaling cascades and cell cycle progression. Therefore, targeting this "Gordian Knot" in HCC cells would be of crucial importance. Here, we suggest that this could be achieved by citrate administration at high concentration, because citrate is a physiologic inhibitor of PFK1 and PFK2. As shown in various in vitro studies, including HCC cell lines, administration of high concentrations of citrate inhibits PFK1 and PFK2 (and consequently glycolysis), decreases ATP production, counteracts HIF-1α and PI3K/AKT signaling, induces apoptosis, and sensitizes cells to cisplatin treatment. Administration of high concentrations of citrate in animal models (including Ras-driven tumours) has been shown to effectively inhibit cancer growth, reverse cell dedifferentiation, and neutralize intratumor acidity, without apparent toxicity in animal studies. Citrate may also induce a rapid secretion of pro-inflammatory cytokines by macrophages, and it could favour the destruction of cancer stem cells (CSCs) sustaining tumor recurrence. Consequently, this "citrate strategy" could improve the tumor sensitivity to current treatments of HCC by reducing the extracellular acidity, thus enhancing the delivery of chemotherapeutic drugs into the tumor. Therefore, we propose that this strategy should be explored in clinical trials, in particular to enhance cTACE effectiveness.

Maternal Fructose Diet-Induced Developmental Programming

Developmental programming of chronic diseases by perinatal exposures/events is the basic tenet of the developmental origins hypothesis of adult disease (DOHaD). With consumption of fructose becoming more common in the diet, the effect of fructose exposure during pregnancy and lactation is of increasing relevance. Human studies have identified a clear effect of fructose consumption on maternal health, but little is known of the direct or indirect effects on offspring. Animal models have been utilized to evaluate this concept and an association between maternal fructose and offspring chronic disease, including hypertension and metabolic syndrome. This review will address the mechanisms of developmental programming by maternal fructose and potential options for intervention.

Fructose Causes Liver Damage, Polyploidy, and Dysplasia in the Setting of Short Telomeres and p53 Loss

Studies in humans and model systems have established an important role of short telomeres in predisposing to liver fibrosis through pathways that are incompletely understood. Recent studies have shown that telomere dysfunction impairs cellular metabolism, but whether and how these metabolic alterations contribute to liver fibrosis is not well understood. Here, we investigated whether short telomeres change the hepatic response to metabolic stress induced by fructose, a sugar that is highly implicated in non-alcoholic fatty liver disease. We find that telomere shortening in telomerase knockout mice (TKO) imparts a pronounced susceptibility to fructose as reflected in the activation of p53, increased apoptosis, and senescence, despite lower hepatic fat accumulation in TKO mice compared to wild type mice with long telomeres. The decreased fat accumulation in TKO is mediated by p53 and deletion of p53 normalizes hepatic fat content but also causes polyploidy, polynuclearization, dysplasia, cell death, and liver damage. Together, these studies suggest that liver tissue with short telomers are highly susceptible to fructose and respond with p53 activation and liver damage that is further exacerbated when p53 is lost resulting in dysplastic changes.