Development of hepatocellular cancer induced by long term low fat-high carbohydrate diet in a NAFLD/NASH mouse model

NAFLD-associated hepatocellular carcinoma (HCC) - A compelling case for repositioning of existing mTORc1 inhibitors

The increasing prevalence of non-alcoholic fatty liver disease (NAFLD) is a growing concern for the high incidence rate of hepatocellular carcinoma (HCC) globally. The progression of NAFLD to HCC is heterogeneous and non-linear, involving intermediate stages of non-alcoholic steatohepatitis (NASH), liver fibrosis, and cirrhosis. There is a high unmet clinical need for appropriate diagnostic, prognostic, and therapeutic options to tackle this emerging epidemic. Unfortunately, at present, there is no validated marker to identify the risk of developing HCC in patients suffering from NAFLD or NASH. Additionally, the current treatment protocols for HCC don't differentiate between viral infection or NAFLD-specific etiology of the HCC and have a limited success rate. The mammalian target of rapamycin complex 1 (mTORc1) is an important protein involved in many vital cellular processes like lipid metabolism, glucose homeostasis, and inflammation. These cellular processes are highly implicated in NAFLD and its progression to severe liver manifestations. Additionally, hyperactivation of mTORc1 is known to promote cell proliferation, which can contribute to the genesis and progression of tumors. Many mTORc1 inhibitors are being evaluated for different types of cancers under various phases of clinical trials. This paper deliberates on the strong pathological implication of the mTORc1 signaling pathway in NAFLD and its progression to NASH and HCC and advocates for a systematic investigation of known mTORc1 inhibitors in suitable pre-clinical models of HCC having NAFLD/NASH-specific etiology.

Both Maternal High-Fat and Post-Weaning High-Carbohydrate Diets Increase Rates of Spontaneous Hepatocellular Carcinoma in Aged-Mouse Offspring

Both maternal obesity and postnatal consumption of obesogenic diets contribute to the development of metabolic dysfunction-associated steatotic liver disease (MASLD) and hepatocellular carcinoma (HCC). However, there is no consensus as to whether diets that are high in fat or carbohydrates/sugars differentially influence the development of HCC. Moreover, the long-term effects of prenatal HF exposure on HCC and whether this is influenced by postnatal diet has not yet been evaluated. C57BL/6 dams were fed either a low-fat, high-carbohydrate control (C) or low-carbohydrate, high-fat (HF) diet. At weaning, male and female offspring were fed the C or HF diet, generating four diet groups: C/C, C/HF, HF/C and HF/HF. Tissues were collected at 16 months of age and livers were assessed for MASLD and HCC. Glucose regulation and pancreatic morphology were also evaluated. Liver tissues were assessed for markers of glycolysis and fatty acid metabolism and validated using a human HCC bioinformatic database. Both C/HF and HF/HF mice developed obesity, hyperinsulinemia and a greater degree of MASLD than C/C and HF/C offspring. However, despite significant liver and pancreas pathology, C/HF mice had the lowest incidence of HCC while tumour burden was highest in HF/C male offspring. The molecular profile of HCC mouse samples suggested an upregulation of the pentose phosphate pathway and a downregulation of fatty acid synthesis and oxidation, which was largely validated in the human dataset. Both pre-weaning HF diet exposure and post-weaning consumption of a high-carbohydrate diet increased the risk of developing spontaneous HCC in aged mice. However, the influence of pre-weaning HF feeding on HCC development appeared to be stronger in the context of post-weaning obesity. As rates of maternal obesity continue to rise, this has implications for the future incidence of HCC and possible dietary manipulation of offspring carbohydrate intake to counteract this risk.

G-Protein-Coupled Receptor 120 Agonist Mitigates Steatotic and Fibrotic Features Triggered in Obese Mice by the Administration of a High-Fat and High-Carbohydrate Diet

Nonalcoholic fatty liver disease (NALFD) represents a complex condition ranging from simple steatosis (nonalcoholic fatty liver, NAFL) to inflammation, and fibrosis is one of the main features of nonalcoholic steatohepatitis (NASH). The pathogenesis of NAFLD is not well established but involves several factors (i.e., predisposition of genetic variants, obesity, and unhealthy lifestyle as unbalanced diets) that lead to an alteration of lipid homeostasis and consequently to an abnormal accumulation of triglycerides and other lipids in the liver parenchyma. Currently, no resolutive pharmacological treatment for NAFLD is available, and the only therapeutic approach is a healthy diet and physical exercise. In this study, we investigated the potential beneficial effect of GprA, a new synthetic agonist of G-protein-coupled receptor 120/free fatty acid receptor 4 (GPR120/FFAR4), in the progression of NAFL/NASH in mice fed for different periods (26 weeks and 30 weeks), with a high-fat (40% kcal) and high-carbohydrate diet, also called a Western-style diet (WSD). In our experimental model, the histological, protein, and transcriptomic analyses highlighted that the GprA can reduce signs of steatosis in WSD-fed mice. Furthermore, in 30 week-treated mice, GprA is also effective in the reduction of collagen deposition and fibrosis development. Altogether, our data validate the central role of FFAR4 in the context of NAFL/NASH onset and progression and reveal that GprA could represent an interesting candidate for the development of a new therapeutic approach in NAFLD treatment.

High-Carbohydrate Diet Consumption Poses a More Severe Liver Cholesterol Deposition than a High-Fat and High-Calorie Diet in Mice

In the past few decades, many researchers believed that a high-fat and high-calorie diet is the most critical factor leading to metabolic diseases. However, increasing evidence shows a high-carbohydrate and low-fat diet may also be a significant risk factor. It needs a comprehensive evaluation to prove which viewpoint is more persuasive. We systematically compared the effects of high-fat and high-calorie diets and high-carbohydrate and low-fat ones on glycolipid metabolism in mice to evaluate and compare the effects of different dietary patterns on metabolic changes in mice. Sixty 8-week-old male C57BL/6 mice were divided into four groups after acclimatization and 15% (F-15), 25% (F-25), 35% (F-35), and 45% (F-45) of their dietary energy was derived from fat for 24 weeks. The body weight, body-fat percentage, fasting blood glucose, lipid content in the serum, and triglyceride content in the livers of mice showed a significantly positive correlation with dietary oil supplementation. Interestingly, the total cholesterol content in the livers of mice in the F-15 group was significantly higher than that in other groups (p < 0.05). Compared with the F-45 group, the mRNA expression of sterol synthesis and absorption-related genes (e.g., Asgr1, mTorc1, Ucp20, Srebp2, Hmgcr, and Ldlr), liver fibrosis-related genes (e.g., Col4a1 and Adamts1) and inflammation-related genes (e.g., Il-1β and Il-6) were significantly higher in the F-15 group. Compared with the F-45 group, the relative abundance of unclassified_f_Lachnospiraceae and Akkermansia was decreased in the F-15 group. While unclassified_f_Lachnospiraceae and Akkermansia are potentially beneficial bacteria, they have the ability to produce short-chain fatty acids and modulate cholesterol metabolism. In addition, the relative abundance of unclassified_f_Lachnospiraceae and Akkermansia was significantly positively correlated with fatty acid transporters expression and negatively correlated with that of cholesteryl acyltransferase 1 and cholesterol synthesis-related genes. In conclusion, our study delineated how a high-fat and high-calorie diet (fat supplied higher than or equal to 35%) induced obesity and hepatic lipid deposition in mice. Although the high-carbohydrate and low-fat diet did not cause weight gain in mice, it induced cholesterol deposition in the liver. The mechanism is mainly through the induction of endogenous synthesis of cholesterol in mice liver through the ASGR1-mTORC1-USP20-HMGCR signaling pathway. The appropriate oil and carbon water ratio (dietary energy supply from fat of 25%) showed the best gluco-lipid metabolic homeostasis in mice.

MiR-182-5p Is Upregulated in Hepatic Tissues from a Diet-Induced NAFLD/NASH/HCC C57BL/6J Mouse Model and Modulates Cyld and Foxo1 Expression

Non-alcoholic fatty liver disease (NAFLD) is considered a relevant liver chronic disease. Variable percentages of NAFLD cases progress from steatosis to steatohepatitis (NASH), cirrhosis and, eventually, hepatocellular carcinoma (HCC). In this study, we aimed to deepen our understanding of expression levels and functional relationships between miR-182-5p and Cyld-Foxo1 in hepatic tissues from C57BL/6J mouse models of diet-induced NAFL/NASH/HCC progression. A miR-182-5p increase was detected early in livers as NAFLD damage progressed, and in tumors compared to peritumor normal tissues. An in vitro assay on HepG2 cells confirmed Cyld and Foxo1, both tumor-suppressor, as miR-182-5p target genes. According to miR-182-5p expression, decreased protein levels were observed in tumors compared to peritumor tissues. Analysis of miR-182-5p, Cyld and Foxo1 expression levels, based on datasets from human HCC samples, showed results consistent with those from our mouse models, and also highlighted the ability of miR-182-5p to distinguish between normal and tumor tissues (AUC 0.83). Overall, this study shows, for the first time, miR-182-5p overexpression and Cyld-Foxo1 downregulation in hepatic tissues and tumors from a diet-induced NAFLD/HCC mouse model. These data were confirmed by the analysis of datasets from human HCC samples, highlighting miR-182-5p diagnostic accuracy and demonstrating the need for further studies to assess its potential role as a biomarker or therapeutic target.

Effect of chia flour associated with high fat diet on intestinal health in female ovariectomized Wistar rats

PURPOSE

The present study aimed to evaluate the effect of chia flour associated with a high fat diet on intestinal health in female ovariectomized Wistar rats.

METHODS

The study was conducted with 32 adult female ovariectomized Wistar rats, which were separated into four groups: standard diet (ST), standard diet with chia (STC), high fat diet (HF) and high fat diet with chia (HFC) for 18 weeks. Cecum content pH, short chain fatty acid content, brush border membrane functionality and morphology and the gut microbiota were evaluated.

RESULTS

This study demonstrated that the consumption of chia flour increased the production of acetic and butyric acids, the longitudinal and circular muscle layers and crypt thickness. It also improved the expression of aminopeptidase (AP) and sucrose-isomaltase (SI) and decreased the cecum content pH. Further, the consumption of chia improved richness and decreased diversity of the microbiota. Operational Taxonomic Units (OTUs) clustering indicated difference between the ST and STC groups. In the linear discriminant analysis effect size (LEfSe) analysis, the Bacteroides genus and members of the Muribaculaceae and Lachnospiraceae families were enriched in the STC treatment group. The STC group demonstrated the enrichment of Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathways related to peptidoglycan and coenzyme A biosynthesis.

CONCLUSION

Our results suggest that chia flour, which is rich in dietary fiber and phenolic compounds, presented potential properties to improve intestinal health.

MiR-22 Deficiency Fosters Hepatocellular Carcinoma Development in Fatty Liver

MiR-22 is mostly considered as a hepatic tumor-suppressor microRNA based on in vitro analyses. Yet, whether miR-22 exerts a tumor-suppressive function in the liver has not been investigated in vivo. Herein, in silico analyses of miR-22 expression were performed in hepatocellular carcinomas from human patient cohorts and different mouse models. Diethylnitrosamine-induced hepatocellular carcinomas were then investigated in lean and diet-induced obese miR-22-deficient mice. The proteome of liver tissues from miR-22-deficient mice prior to hepatocellular carcinoma development was further analyzed to uncover miR-22 regulated factors that impact hepatocarcinogenesis with miR-22 deficiency. MiR-22 downregulation was consistently observed in hepatocellular carcinomas from all human cohorts and mouse models investigated. The time of appearance of the first tumors was decreased and the number of tumoral foci induced by diethylnitrosamine was significantly increased by miR-22-deficiency in vivo, two features which were further drastically exacerbated with diet-induced obesity. At the molecular level, we provide evidence that the loss of miR-22 significantly affects the energetic metabolism and mitochondrial functions of hepatocytes, and the expression of tumor-promoting factors such as thrombospondin-1. Our study demonstrates that miR-22 acts as a hepatic tumor suppressor in vivo by restraining pro-carcinogenic metabolic deregulations through pleiotropic mechanisms and the overexpression of relevant oncogenes.

Sugars and Gastrointestinal Health

Sugar overconsumption is linked to a rise in the incidence of noncommunicable diseases such as diabetes, cardiovascular diseases, and cancer. This increased incidence is becoming a real public health problem that is more severe than infectious diseases, contributing to 35 million deaths annually. Excessive intake of free sugars can cause many of the same health problems as excessive alcohol consumption. Many recent international recommendations have expressed concerns about sugar consumption in Westernized societies, as current consumption levels represent quantities with no precedent during hominin evolution. In both adults and children, the World Health Organization strongly recommends reducing free sugar intake to <10% of total energy intake and suggests a further reduction to below 5%. Most studies have focused on the deleterious effects of Western dietary patterns on global health and the intestine. Whereas excessive dietary fat consumption is well studied, the specific impact of sugar is poorly described, while refined sugars represent up to 40% of caloric intake within industrialized countries. However, high sugar intake is associated with multiple tissue and organ dysfunctions. Both hyperglycemia and excessive sugar intake disrupt the intestinal barrier, thus increasing gut permeability and causing profound gut microbiota dysbiosis, which results in a disturbance in mucosal immunity that enhances infection susceptibility. This review aims to highlight the roles of different types of dietary carbohydrates and the consequences of their excessive intake for intestinal homeostasis.

Role of exosomal microRNAs in cancer therapy and drug resistance mechanisms: focus on hepatocellular carcinoma

Extracellular vesicles (EVs), defined as intercellular messengers that carry their cargos between cells, are involved in several physiological and pathological processes. These small membranous vesicles are released by most cells and contain biological molecules, including nucleic acids, proteins and lipids, which can modulate signaling pathways of nearby or distant recipient cells. Exosomes, one the most characterized classes of EVs, include, among others, microRNAs (miRNAs), small non-coding RNAs able to regulate the expression of several genes at post-transcriptional level. In cancer, exosomal miRNAs have been shown to influence tumor behavior and reshape tumor microenvironment. Furthermore, their possible involvement in drug resistance mechanisms has become evident in recent years. Hepatocellular carcinoma (HCC) is the major type of liver cancer, accounting for 75-85% of all liver tumors. Although the improvement in HCC treatment approaches, low therapeutic efficacy in patients with intermediate-advanced HCC is mainly related to the development of tumor metastases, high risk of recurrence and drug resistance. Exosomes have been shown to be involved in pathogenesis and progression of HCC, as well as in drug resistance, by regulating processes such as cell proliferation, epithelial-mesenchymal transition and immune response. Herein, we summarize the current knowledge about the involvement of exosomal miRNAs in HCC therapy, highlighting their role as modulators of therapeutic response, particularly chemotherapy and immunotherapy, as well as possible therapeutic tools.

Ferroptosis resistance cooperates with cellular senescence in the overt stage of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis

Cellular senescence and ferroptosis are the two main, fine-tuned processes in tissue damage restraint; however, they can be overactivated in pathologies such as nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH), becoming dangerous stimuli. Senescence is characterized by a decline in cell division and an abnormal release of reactive oxygen species (ROS), and ferroptosis is represented by iron deposition associated with an excessive accumulation of ROS. ROS and cellular stress pathways are also drivers of NAFLD/NASH development. The etiology of NAFLD/NASH lies in poor diets enriched in fat and sugar. This food regimen leads to liver steatosis, resulting in progressive degeneration of the organ, with a late onset of irreversible fibrosis and cirrhosis. Few studies have investigated the possible connection between senescence and ferroptosis in NAFLD/NASH progression, despite the two events sharing some molecular players. We hypothesized a possible link between senescence and ferroptosis in a NAFLD background. To thoroughly investigate this in the context of "Western-style" diet (WSD) abuse, we used an amylin-modified liver NASH mouse model. The main NASH hallmarks have been confirmed in this model, as well as an increase in apoptosis, and Ki67 and p53 expression in the liver. Senescent beta-galactosidase-positive cells were elevated, as well as the expression of the related secretory molecules Il-6 and MMP-1. Features of DNA damage and iron-overload were found in the livers of NASH mice. Gpx4 (glutathione peroxidase 4) expression, counteracting ferroptotic cell death, was increased. Notably, an increased number of senescent cells showing overexpression of gpx4 was also found. Our data seem to suggest that senescent cells acquire a gpx4-mediated mechanism of ferroptosis resistance and thus remain in the liver, fostering the deterioration of liver fitness.

The antiinflammatory and antifibrotic effect of olive phenols and Lactiplantibacillus plantarum IMC513 in dextran sodium sulfate-induced chronic colitis

OBJECTIVES

After a chronic intestinal injury, several intestinal cells switch their phenotype to activated myofibroblasts, which in turn release an abnormal amount of extracellular matrix proteins, leading to the onset of the fibrotic process. To date, no resolutive pharmacological treatments are available, and the identification of new therapeutic approaches represents a crucial goal to achieve. The onset, maintenance, and progression of inflammatory bowel disease are related to abnormal intestinal immune responses to environmental factors, including diet and intestinal microflora components. This study aimed to evaluate the potential antiinflammatory and antifibrotic effect of a biologically debittered olive cream and its probiotic oral administration in an experimental model of dextran sodium sulfate (DSS)-induced chronic colitis.

METHODS

Chronic colitis was induced in mice by three cycles of oral administration of 2.5% DSS (5 d of DSS followed by 7 d of tap water). Mice were randomly divided into five groups: 10 control mice fed with standard diet (SD), 20 mice receiving SD and DSS (SD+DSS), 20 mice receiving an enriched diet (ED) with olive cream and DSS (ED+DSS), 20 mice receiving SD plus probiotics (PB; Lactiplantibacillus plantarum IMC513) and DSS (SD+PB+DSS), and 20 mice receiving ED plus PB and DSS (ED+ PB+DSS). Clinical features and large bowel macroscopic, histologic, and immunohistochemical findings were evaluated.

RESULTS

The simultaneous administration of ED and PB induced a significant reduction in macroscopic and microscopic colitis scores compared with the other DSS-treated groups. In addition, ED and PB led to a significant decrease in the expression of inflammatory cytokines and profibrotic molecules.

CONCLUSIONS

The concomitant oral administration of a diet enriched with biologically debittered olive cream and a specific probiotic strain (Lactiplantibacillus plantarum IMC513) can exert synergistic antiinflammatory and antifibrotic action in DSS-induced chronic colitis. Further studies are needed to define the cellular and molecular mechanisms modulated by olive cream compounds and by Lactiplantibacillus plantarum IMC513.

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

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

Reenvisioning Traditional to Regenerative Therapeutic Advances in Managing Nonalcoholic Fatty Liver Disease in Diabetes Mellitus

Reports indicate the increasing prevalence of liver disorders in diabetes mellitus (DM) patients. Clinically, it has also been revealed that the existence of nonalcoholic fatty liver disease (NAFLD) enhances the incidence of type 2 diabetes mellitus (T2DM), while T2DM exacerbates NAFLD to extremely severe forms of steatohepatitis, cirrhosis, and hepatocellular carcinoma. This implies the coexistence and bidirectional nature of NAFLD and T2DM, which function synergistically to drive adverse consequences in clinical practice. For treatment of such comorbid state, though the existing practices such as lifestyle management, traditional Chinese medicines (TCM), and pharmaceuticals have offered somewhat relief, the debate continues about the optimal therapeutic impacts. Recent developments in the field of tissue engineering have led to a renewed interest in novel biomaterial alternatives such as stem cells. This might be attributable to their differentiation potential towards hepatic and pancreatic lineage. These cellular therapies could be further complemented by platelet-derived biomaterials, TCM formulations, or any specific drug. Based on these abovementioned approaches, we aimed to comprehensively analyze various preclinical and clinical studies from traditional to regenerative therapeutic approaches in managing concomitant NAFLD and T2DM.

CD36 and DGAT2 facilitate the lipid-lowering effect of chitooligosaccharides via fatty acid intake and triglyceride synthesis signaling

This study examined the impact of chitobiose (GlcN)2 and chitotriose (GlcN)3 on lipid accumulation modification and their inhibitory functionalities. (GlcN)2 and (GlcN)3 significantly inhibited the total cholesterol (TC), triglyceride (TG), and low-density lipid cholesterol (LDL-c) levels in the liver of the ob/ob-/- mice fed a non-high-fat diet. This phenomenon was associated with a reduction in the mRNA and protein expression of TG synthesis and fatty acid uptake-related signaling, significantly affecting the cluster of differentiation 36 (CD36) and diacylglycerol acyltransferase 2 (DGAT2). Furthermore, the CD36 and DGAT2 genes were overexpressed by constructing a plasmid and transfecting it into HepG2 cells, after which the phenotypic traits of lipid accumulation were assessed in vitro. Consequently, it was evident that (GlcN)2 and (GlcN)3 reduced the overexpression of these proteins and relieved cellular lipid accumulation. In conclusion, these results indicated that (GlcN)2 and (GlcN)3 acted positively against NAFLD while regulating steatosis in the non-high-fat diet NAFLD model. The potential NAFLD treatment strategies, such as targeting CD36 and DGAT2 signaling, could provide scientific insight into further applying food-derived ingredients to reduce the risk of high-fat metabolism.

Prolonged Chronic Consumption of a High Fat with Sucrose Diet Alters the Morphology of the Small Intestine

(1) The high-fat diet (HFD) of western countries has dramatic effect on the health of several organs, including the digestive tract, leading to the accumulation of fats that can also trigger a chronic inflammatory process, such as that which occurs in non-alcohol steatohepatitis. The effects of a HFD on the small intestine, the organ involved in the absorption of this class of nutrients, are still poorly investigated. (2) To address this aspect, we administered a combined HFD with sucrose (HFD w/Suc, fat: 58% Kcal) regimen (18 months) to mice and investigated the morphological and molecular changes that occurred in the wall of proximal tract of the small intestine compared to the intestine of mice fed with a standard diet (SD) (fat: 18% Kcal). (3) We found an accumulation of lipid droplets in the mucosa of HFD w/Suc-fed mice that led to a disarrangement of mucosa architecture. Furthermore, we assessed the expression of several key players involved in lipid metabolism and inflammation, such as perilipin, leptin, leptin receptor, PI3K, p-mTOR, p-Akt, and TNF-α. All these molecules were increased in HFD mice compared to the SD group. We also evaluated anti-inflammatory molecules like adiponectin, adiponectin receptor, and PPAR-γ, and observed their significant reduction in the HFD w/Suc group compared to the control. Our data are in line with the knowledge that improper eating habits present a primary harmful assault on the bowel and the entire body's health. (4) These results represent a promising starting point for future studies, helping to better understand the complex and not fully elucidated spectrum of intestinal alterations induced by the overconsumption of fat.

Current innovations in nutraceuticals and functional foods for intervention of non-alcoholic fatty liver disease

As innovations in global agricultural production and food trading systems lead to major dietary shifts, high morbidity rates from non-alcoholic fatty liver disease (NAFLD), accompanied by elevated risk of lipid metabolism-related complications, has emerged as a growing problem worldwide. Treatment and prevention of NAFLD and chronic liver disease depends on the availability of safe, effective, and diverse therapeutic agents, the development of which is urgently needed. Supported by a growing body of evidence, considerable attention is now focused on interventional approaches that combines nutraceuticals and functional foods. In this review, we summarize the pathological progression of NAFLD and discuss the beneficial effects of nutraceuticals and the active ingredients in functional foods. We also describe the underlying mechanisms of these compounds in the intervention of NAFLD, including their effects on regulation of lipid homeostasis, activation of signaling pathways, and their role in gut microbial community dynamics and the gut-liver axis. In order to identify novel targets for treatment of lipid metabolism-related diseases, this work broadly explores the molecular mechanism linking nutraceuticals and functional foods, host physiology, and gut microbiota. Additionally, the limitations in existing knowledge and promising research areas for development of active interventions and treatments against NAFLD are discussed.

Dietary Management of Obesity: A Review of the Evidence

Obesity is a multi-factorial disease and its prevention and management require knowledge of the complex interactions underlying it and adopting a whole system approach that addresses obesogenic environments within country specific contexts. The pathophysiology behind obesity involves a myriad of genetic, epigenetic, physiological, and macroenvironmental factors that drive food intake and appetite and increase the obesity risk for susceptible individuals. Metabolically, food intake and appetite are regulated via intricate processes and feedback systems between the brain, gastrointestinal system, adipose and endocrine tissues that aim to maintain body weight and energy homeostasis but are also responsive to environmental cues that may trigger overconsumption of food beyond homeostatic needs. Under restricted caloric intake conditions such as dieting, these processes elicit compensatory metabolic mechanisms that promote energy intake and weight regain, posing great challenges to diet adherence and weight loss attempts. To mitigate these responses and enhance diet adherence and weight loss, different dietary strategies have been suggested in the literature based on their differential effects on satiety and metabolism. In this review article, we offer an overview of the literature on obesity and its underlying pathological mechanisms, and we present an evidence based comparative analysis of the effects of different popular dietary strategies on weight loss, metabolic responses and diet adherence in obesity.

Hyperinsulinaemia in cancer

Elevated circulating insulin levels are frequently observed in the setting of obesity and early type 2 diabetes, as a result of insensitivity of metabolic tissues to the effects of insulin. Higher levels of circulating insulin have been associated with increased cancer risk and progression in epidemiology studies. Elevated circulating insulin is believed to be a major factor linking obesity, diabetes and cancer. With the development of targeted cancer therapies, insulin signalling has emerged as a mechanism of therapeutic resistance. Although metabolic tissues become insensitive to insulin in the setting of obesity, a number of mechanisms allow cancer cells to maintain their ability to respond to insulin. Significant progress has been made in the past decade in understanding the insulin receptor and its signalling pathways in cancer, and a number of lessons have been learnt from therapeutic failures. These discoveries have led to numerous clinical trials that have aimed to reduce the levels of circulating insulin and to abrogate insulin signalling in cancer cells. With the rising prevalence of obesity and diabetes worldwide, and the realization that hyperinsulinaemia may contribute to therapeutic failures, it is essential to understand how insulin and insulin receptor signalling promote cancer progression.

Hepatocellular Carcinoma Emergence in Diabetic Mice with Non-Alcoholic Steatohepatitis Depends on Diet and Is Delayed in Liver Exhibiting an Active Immune Response

The increase of the sedentary lifestyle and high-calorie diet have modified the etiological landscape of hepatocellular carcinoma (HCC), with a recrudescence of non-alcoholic fatty liver disease (NAFLD), especially in Western countries. The purpose of our study was to evaluate the impact of high-fat diet feeding on non-alcoholic steatohepatitis (NASH) establishment and HCC development. Streptozotocin-induced diabetic male mice were fed with high-fat-high-cholesterol diet (HFHCD) or high-fat-high-sugar diet (HFHSD) from 1 to 16 weeks. Even if liver tumors appear regardless of the high-fat diet, two distinct physiopathological patterns were evidenced, with much more severe NASH hallmarks (liver injury, inflammation and fibrosis) in diabetic mice fed with HFHCD. The mild hepatic injury, weak inflammation and fibrosis observed in HFHSD were interestingly associated with earlier emergence of more numerous liver tumors. When activated helper and cytotoxic T cells, detected by flow cytometry, infiltrated the liver of HFHCD-fed diabetic mice, a delay in the appearance of tumor nodules and a limitation of their numbers were observed, suggesting that the immune activities partly controlled tumor emergence. These data highlighted two different mouse models of HCC progression in diabetic mice depending on diet, which could be useful to evaluate new therapeutic approaches for HCC by targeting the immune response.

Long-term abuse of a high-carbohydrate diet is as harmful as a high-fat diet for development and progression of liver injury in a mouse model of NAFLD/NASH

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) has become the most common liver disease globally. It is caused by a complex network of factors, including diet. The hallmark of NAFLD is the benign accumulation of triacylglycerols, however, this condition may worsen into non-alcoholic steatohepatitis (NASH), a more severe form associated with inflammation and fibrosis. Currently, no therapies are available, and diet modifications are the only strategy. Although there is increasing evidence emerging about how an abuse of carbohydrates could be involved in the progression of liver injury, a comprehensive understanding of the damage induced by an enriched carbohydrate diet is still far from complete. The aim of this study was to investigate and compare the effects of a low-fat/high-carbohydrate diet (LF-HCD) with high-fat (HFD) and standard (SD) diets in a nutritional mouse model of NAFLD/NASH.

METHODS

Histologic, real-time polymerase chain reaction, and immunohistochemical evaluations were performed.

RESULTS

The results showed that the prolonged abuse of both LF-HCDs and HFDs induced a significant increase in hepatic steatosis, inflammation, and fibrosis scores compared with SD. At the same time, both LF-HCDs and HFDs led to significant increases in the expression of the molecules involved in the progression of NAFLD that we assessed (perilipin, CD68, TGF-β1, CTGF, leptin, leptin receptor, and α-SMA).

CONCLUSIONS

The present study highlighted that the simple substitution of fats with carbohydrates is not a proper strategy to prevent or mitigate the progression of NAFLD/NASH. Further studies are required to define the best nutritional strategy to prevent NAFLD and its related metabolic syndrome.

[The role of iron overload in the progression of nonalcoholic steatohepatitis (NASH)]

Non-alcoholic steatohepatitis (NASH), one of the most common chronic liver diseases (CLD), is getting the most important cause of cirrhosis and hepatocellular carcinoma. Iron is an essential micronutrient for organisms. Once excess iron is accumulated in vital organs, dysfunctions of these organs can occur via the generation of reactive oxygen species. Hepatic iron overload is often seen in CLD patients. In NASH patients, iron accumulation in the liver is positively correlated with histological severity. Thus iron overload can contribute to progression of nonalcoholic fatty liver disease (NAFLD) to NASH. In a rat model of NASH, feeding of high-fat and high-iron diet increases hepatic inflammation with increased hepatic cytokine expression compared with feeding of high-fat diet only. In this model, iron is intensely accumulated in Kupffer cells/macrophages within the lesion, raising the possibility that iron-laden Kupffer cells/macrophages can play a key role in the enhancement of hepatic inflammation in NASH condition. On the other hand, in a rat model of liver cirrhosis, dietary iron overload clearly abrogates the development and progression of liver cirrhosis induced by repeated administration of thioacetamide (TAA). These findings suggest that iron overload can promote or suppress chronic liver diseases depending on the tissue microenvironment. Here we review and introduce the recent findings on the pathological roles of iron overload in the development and progression of NAFLD/NASH.

Deranged hepatocyte intracellular Ca2+ homeostasis and the progression of non-alcoholic fatty liver disease to hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths in men, and the sixth in women. Non-alcoholic fatty liver disease (NAFLD) is now one of the major risk factors for HCC. NAFLD, which involves the accumulation of excess lipid in cytoplasmic lipid droplets in hepatocytes, can progress to non-alcoholic steatosis, fibrosis, and HCC. Changes in intracellular Ca²⁺ constitute important signaling pathways for the regulation of lipid and carbohydrate metabolism in normal hepatocytes. Recent studies of steatotic hepatocytes have identified lipid-induced changes in intracellular Ca²⁺, and have provided evidence that altered Ca²⁺ signaling exacerbates lipid accumulation and may promote HCC. The aims of this review are to summarise current knowledge of the lipid-induced changes in hepatocyte Ca²⁺ homeostasis, to comment on the mechanisms involved, and discuss the pathways leading from altered Ca²⁺ homeostasis to enhanced lipid accumulation and the potential promotion of HCC. In steatotic hepatocytes, lipid inhibits store-operated Ca²⁺ entry and SERCA2b, and activates Ca²⁺ efflux from the endoplasmic reticulum (ER) and its transfer to mitochondria. These changes are associated with changes in Ca²⁺ concentrations in the ER (decreased), cytoplasmic space (increased) and mitochondria (likely increased). They lead to: inhibition of lipolysis, lipid autophagy, lipid oxidation, and lipid secretion; activation of lipogenesis; increased lipid; ER stress, generation of reactive oxygen species (ROS), activation of Ca²⁺/calmodulin-dependent kinases and activation of transcription factor Nrf2. These all can potentially mediate the transition of NAFLD to HCC. It is concluded that lipid-induced changes in hepatocyte Ca²⁺ homeostasis are important in the initiation and progression of HCC. Further research is desirable to better understand the cause and effect relationships, the time courses and mechanisms involved, and the potential of Ca²⁺ transporters, channels, and binding proteins as targets for pharmacological intervention.

Protective Effects of Licochalcone A Ameliorates Obesity and Non-Alcoholic Fatty Liver Disease Via Promotion of the Sirt-1/AMPK Pathway in Mice Fed a High-Fat Diet

Licochalcone A is a chalcone isolated from Glycyrrhiza uralensis. It showed anti-tumor and anti-inflammatory properties in mice with acute lung injuries and regulated lipid metabolism through the activation of AMP-activated protein kinase (AMPK) in hepatocytes. However, the effects of licochalcone A on reducing weight gain and improving nonalcoholic fatty liver disease (NAFLD) are unclear. Thus, the present study investigated whether licochalcone A ameliorated weight loss and lipid metabolism in the liver of high-fat diet (HFD)-induced obese mice. Male C57BL/6 mice were fed an HFD to induce obesity and NAFLD, and then were injected intraperitoneally with licochalcone A. In another experiment, a fatty liver cell model was established by incubating HepG2 hepatocytes with oleic acid and treating the cells with licochalcone A to evaluate lipid metabolism. Our results demonstrated that HFD-induced obese mice treated with licochalcone A had decreased body weight as well as inguinal and epididymal adipose tissue weights compared with HFD-treated mice. Licochalcone A also ameliorated hepatocyte steatosis and decreased liver tissue weight and lipid droplet accumulation in liver tissue. We also found that licochalcone A significantly regulated serum triglycerides, low-density lipoprotein, and free fatty acids, and decreased the fasting blood glucose value. Furthermore, in vivo and in vitro, licochalcone A significantly decreased expression of the transcription factor of lipogenesis and fatty acid synthase. Licochalcone A activated the sirt-1/AMPK pathway to reduce fatty acid chain synthesis and increased lipolysis and β-oxidation in hepatocytes. Licochalcone A can potentially ameliorate obesity and NAFLD in mice via activation of the sirt1/AMPK pathway.

Role of MicroRNAs in Pathophysiology of Non-alcoholic Fatty Liver Disease and Non-alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder worldwide. It includes wide range of diseases from different subtypes of simple steatosis to non-alcoholic steatohepatitis (NASH), which may be complicated by liver fibrosis, cirrhosis, or hepatocellular carcinoma. Of the epigenetic factors that play a key role in the progression of it, is microRNAs (miRNAs).

MiRNAs are short non-coding RNAs of 22-23 nucleotides in length, which regulate a large number of genes that have a critical role in regulation of lipid and cholesterol biosynthesis in hepatocytes. MiRNAs can be used as a very powerful biomarker to diagnosis and follow-up any disorder, such as NAFLD and NASH with a high specificity and sensitivity. The aim of this study was to review the role of different miRNAs in the pathophysiology of NASH and NAFLD

Dietary Iron Supplementation Alters Hepatic Inflammation in a Rat Model of Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is now the most common liver disease in the world. NAFLD can progress to nonalcoholic steatohepatitis (NASH), cirrhosis and eventually hepatocellular carcinoma. Acquired hepatic iron overload is seen in a number of patients with NAFLD; however, its significance in the pathology of NAFLD is still debated. Here, we investigated the role of dietary iron supplementation in experimental steatohepatitis in rats. Rats were fed a control, high-fat (HF), high-fat high-iron (HFHI) and high-iron (HI) diet for 30 weeks. Blood biochemical, histopathological and gut microbiota analyses were performed. Rats in HF and HFHI groups showed an ALT-dominant elevation of serum transaminases, hepatic steatosis, hepatic inflammation, and upregulation of proinflammatory cytokines. The number of large inflammatory foci, corresponding to lobular inflammation in NASH patients, was significantly higher in HFHI than in HF group; within the lesion, macrophages with intense iron staining were observed. Hepatic expression of TNFα was higher in HFHI than that in HF group. There was no significant change in hepatic oxidative stress, gut microbiota or serum endotoxin levels between HF and HFHI groups. These results suggested that dietary iron supplementation enhances experimental steatohepatitis induced by long-term high-fat diet feeding in rats. Iron-laden macrophages can play an important role in the enhancement of hepatic inflammation.