Nonalcoholic Fatty Liver Disease In Humans Research Articles

Vinpocetine and Lactobacillus improve fatty liver in rats: role of adiponectin and gut microbiome

Therapeutics that interfere with the damage/pathogen-associated molecular patterns (DAMPs/PAMPs) have evolved as promising candidates for hepatic inflammation like that occurring in non-alcoholic fatty liver disease (NAFLD). In the current study, we examined the therapeutic impact of the phosphodiesterase-1 inhibitor vinpocetine (Vinpo), alone or when combined with Lactobacillus, on hepatic abnormalities caused by a 13-week high-fat diet (HFD) and diabetes in rats. The results show that Vinpo (10 and 20 mg/kg/day) dose-dependently curbed HFD-induced elevation of liver injury parameters in serum (ALT, AST) and tissue histopathology. These effects were concordant with Vinpo’s potential to ameliorate HFD-induced fibrosis (Histological fibrosis score, hydroxyproline, TGF-β1) and oxidative stress (MDA, NOx) alongside restoring the antioxidant-related parameters (GSH, SOD, Nrf-2, HO-1) in the liver. Mechanistically, Vinpo attenuated the hepatocellular release of DAMPs like high mobility group box (HMGB)1 alongside lowering the overactivation of the pattern recognition receptors including, toll-like receptor (TLR)4 and receptor for advanced glycation end-products (RAGE). Consequently, there was less activation of the transcription factor nuclear factor-kappa B that lowered production of the proinflammatory cytokines TNF-α and IL-6 in Vinpo-treated HFD/diabetes rats. Compared to Vinpo treatment alone, Lactobacillus probiotics as adjunctive therapy with Vinpo significantly improved the disease-associated inflammation and oxidative stress injury, as well as the insulin resistance and lipid profile abnormalities via enhancing the restoration of the symbiotic microbiota. In conclusion, combining Vinpo and Lactobacillus probiotics may be a successful approach for limiting NAFLD in humans.

Development of fatty liver disease model using high cholesterol and low choline diet in white leghorn chickens

Nonalcoholic fatty liver disease (NAFLD), which shows similar symptoms as fatty liver hemorrhage syndrome (FLHS) in chickens, is the most common cause of chronic liver disease and cancer in humans. NAFLD patients and FLHS in chickens have demonstrated severe liver disorders when infected by emerging strains of human hepatitis E virus (HEV) and avian HEV, respectively. We sought to develop a fatty liver disease chicken model by altering the diet of 3-week-old white leghorn chickens. The high cholesterol, and low choline (HCLC) diet included 7.6% fat with additional 2% cholesterol and 800 mg/kg choline in comparison to 5.3% fat, and 1,300 mg/kg choline in the regular diet. Our diet induced fatty liver avian model successfully recapitulates the clinical features seen during NAFLD in humans and FLHS in chickens, including hyperlipidemia and hepatic steatosis, as indicated by significantly higher serum triglycerides, serum cholesterol, liver triglycerides, cholesterol, and fatty acids. By developing this chicken model, we expect to provide a platform to explore the role of lipids in the liver pathology linked with viral infections and contribute to the development of prophylactic interventions.

Coprococcus protects against high-fat diet-induced nonalcoholic fatty liver disease in mice.

The incidence of nonalcoholic fatty liver disease (NAFLD) is increasing annually, leading to substantial medical and health burdens. Numerous studies have demonstrated the potential effectiveness of intestinal probiotics as a treatment strategy for NAFLD. Therefore, the objective of this study is to identify a probiotic for the treatment of NAFLD. In this study, blood and fecal samples were collected from 41 healthy volunteers and 44 patients diagnosed with NAFLD. Analysis of the 16S rDNA sequencing data and quantitative real-time PCR (RT-qPCR) revealed a significant reduction in the abundance of Coprococcus in NAFLD patients. Subsequent animal experiments demonstrated that Coprococcus was able to effectively reverse liver lipid accumulation, inflammation, and fibrosis induced by a high-fat diet (HFD) in mice. This study provides the first in vivo evidence that Coprococcus is a beneficial bacterium capable of preventing NAFLD and has the same probiotic effect in mice as Lactobacillus GG (LGG), a positive control. Therefore, Coprococcus has the potential to serve as a probiotic for the prevention and treatment of NAFLD in humans.

Relationship between serum β-hydroxybutyrate and hepatic fatty acid oxidation in individuals with obesity and NAFLD.

Nonalcoholic fatty liver disease (NAFLD) is characterized by excess lipid accumulation that can progress to inflammation (nonalcoholic steatohepatitis, NASH), and fibrosis. Serum β-hydroxybutyrate (β-HB), a product of the ketogenic pathway, is commonly used as a surrogate marker for hepatic fatty acid oxidation (FAO). However, it remains uncertain whether this relationship holds true in the context of NAFLD in humans. We compared fasting serum β-HB levels with direct measurement of liver mitochondrial palmitate oxidation in humans stratified based on NAFLD severity (n = 142). Patients were stratified based on NAFLD activity score (NAS): NAS = 0 (no disease), NAS = 1-2 (mild), NAS = 3-4 (moderate), and NAS ≥ 5 (advanced). Moderate and advanced NAFLD is associated with reductions in liver 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), serum β-HB, but not 3-hydroxy-3-methylglutaryl-CoA lyase (HMGCL) mRNA, relative to no disease. Worsening liver mitochondrial complete palmitate oxidation corresponded with lower HMGCS2 mRNA but not total (complete + incomplete) palmitate oxidation. Interestingly, we found that liver HMGCS2 mRNA and serum β-HB correlated with liver mitochondrial β-hydroxyacyl-CoA dehydrogenase (β-HAD) activity and CPT1A mRNA. Also, lower mitochondrial mass and markers of mitochondrial turnover positively correlated with lower HMGCS2 in the liver. These data suggest that liver ketogenesis and FAO occur at comparable rates in individuals with NAFLD. Our findings support the utility of serum β-HB to serve as a marker of liver injury and hepatic FAO in the context of NAFLD.NEW & NOTEWORTHY Serum β-hydroxybutyrate (β-HB) is frequently utilized as a surrogate marker for hepatic fatty acid oxidation; however, few studies have investigated this relationship during states of liver disease. We found that the progression of nonalcoholic fatty liver disease (NAFLD) is associated with reductions in circulating β-HB and liver 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2). As well, decreased rates of hepatic fatty acid oxidation correlated with liver HMGCS2 mRNA and serum β-HB. Our work supports serum β-HB as a potential marker for hepatic fatty acid oxidation and liver injury during NAFLD.

Hepatic FASN deficiency differentially affects nonalcoholic fatty liver disease and diabetes in mouse obesity models.

Nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes are interacting comorbidities of obesity, and increased hepatic de novo lipogenesis (DNL), driven by hyperinsulinemia and carbohydrate overload, contributes to their pathogenesis. Fatty acid synthase (FASN), a key enzyme of hepatic DNL, is upregulated in association with insulin resistance. However, the therapeutic potential of targeting FASN in hepatocytes for obesity-associated metabolic diseases is unknown. Here, we show that hepatic FASN deficiency differentially affects NAFLD and diabetes depending on the etiology of obesity. Hepatocyte-specific ablation of FASN ameliorated NAFLD and diabetes in melanocortin 4 receptor-deficient mice but not in mice with diet-induced obesity. In leptin-deficient mice, FASN ablation alleviated hepatic steatosis and improved glucose tolerance but exacerbated fed hyperglycemia and liver dysfunction. The beneficial effects of hepatic FASN deficiency on NAFLD and glucose metabolism were associated with suppression of DNL and attenuation of gluconeogenesis and fatty acid oxidation, respectively. The exacerbation of fed hyperglycemia by FASN ablation in leptin-deficient mice appeared attributable to impairment of hepatic glucose uptake triggered by glycogen accumulation and citrate-mediated inhibition of glycolysis. Further investigation of the therapeutic potential of hepatic FASN inhibition for NAFLD and diabetes in humans should thus consider the etiology of obesity.

USP14 governs CYP2E1 to promote nonalcoholic fatty liver disease through deubiquitination and stabilization of HSP90AA1

Nonalcoholic fatty liver disease (NAFLD) begins with excessive triglyceride accumulation in the liver, and overly severe hepatic steatosis progresses to nonalcoholic steatohepatitis (NASH), which is characterized by lipid peroxidation, inflammation, and fibrosis. Ubiquitin-specific proteinase 14 (USP14) regulates inflammation, hepatocellular carcinoma and viral infection, but the effect of USP14 on NAFLD is unknown. The aim of this study was to reveal the role of USP14 in the progression of NAFLD and its underlying mechanism. We demonstrated that hepatic USP14 expression was significantly increased in NAFLD in both humans and mice. Hepatic USP14 overexpression exacerbated diet-induced hepatic steatosis, inflammation and fibrosis in mice, in contrast to the results of hepatic USP14 knockdown. Furthermore, palmitic/oleic acid-induced lipid peroxidation and inflammation in hepatocytes were markedly increased by USP14 overexpression but decreased by USP14 knockdown. Notably, in vivo or in vitro data show that USP14 promotes NAFLD progression in a cytochrome p4502E1 (CYP2E1)-dependent manner, which exacerbates hepatocyte oxidative stress, impairs the mitochondrial respiratory chain and inflammation by promoting CYP2E1 protein levels. Mechanistically, we demonstrated by immunoprecipitation and ubiquitination analysis that USP14 inhibits the degradation of heat shock protein 90 alpha family class A member 1 (HSP90AA1) by decreasing its lysine 48-linkage ubiquitination. Meanwhile, upregulation of HAP90AA1 protein promotes CYP2E1 protein accumulation. Collectively, our data indicate that an unknown USP14-HSP90AA1-CYP2E1 axis contributes to NAFLD progression, and we propose that inhibition of USP14 may be an effective strategy for NASH treatment.

Inhibition of VEGF-B signaling prevents non-alcoholic fatty liver disease development by targeting lipolysis in the white adipose tissue

Hepatic steatosis is a hallmark of non-alcoholic fatty liver disease (NAFLD), a common comorbidity in type 2 diabetes mellitus (T2DM). The pathogenesis of NAFLD is complex and involves the crosstalk between the liver and the white adipose tissue (WAT). Vascular endothelial growth factor B (VEGF-B) has been shown to control tissue lipid accumulation by regulating the transport properties of the vasculature. The role of VEGF-B signaling and the contribution to hepatic steatosis and NAFLD in T2DM is currently not understood. C57BL/6J mice treated with a neutralizing antibody against VEGF-B, or mice with adipocyte-specific overexpression or under-expression of VEGF-B (AdipoqCre+/VEGF-BTG/+ mice and AdipoqCre+/Vegfbfl/+mice) were subjected to a 6-month high-fat diet (HFD), or chow-diet, whereafter NAFLD development was assessed. VEGF-B expression was analysed in WAT biopsies from patients with obesity and NAFLD in a pre-existing clinical cohort (n= 24 patients with NAFLD and n= 24 without NAFLD) and correlated to clinicopathological features. Pharmacological inhibition of VEGF-B signaling in diabetic mice reduced hepatic steatosis and NAFLD by blocking WAT lipolysis. Mechanistically we show, by using HFD-fed AdipoqCre+/VEGF-BTG/+ mice and HFD-fed AdipoqCre+/Vegfbfl/+mice, that inhibition of VEGF-B signaling targets lipolysis in adipocytes. Reducing VEGF-B signaling ameliorated NAFLD by decreasing WAT inflammation, resolving WAT insulin resistance, and lowering the activity of the hormone sensitive lipase. Analyses of human WAT biopsies from individuals with NAFLD provided evidence supporting the contribution of VEGF-B signaling to NAFLD development. VEGF-B expression levels in adipocytes from two WAT depots correlated with development of dysfunctional WAT and NAFLD in humans. Taken together, our data from mouse models and humans suggest that VEGF-B antagonism may represent an approach to combat NAFLD by targeting hepatic steatosis through suppression of lipolysis. Non-alcoholic fatty liver disease (NAFLD) is a common comorbidity in type 2 diabetes mellitus (T2DM) and has a global prevalence of between 25-29%. There are currently no approved drugs for NAFLD, and given the scale of the ongoing diabetes epidemics, there is an urgent need to identify new treatment options. Our work suggests that VEGF-B antagonism may represent an approach to combat NAFLD by targeting hepatic steatosis through suppression of lipolysis. The neutralizing anti-VEGF-B antibody, which was used in this study, has already entered clinical trials for patients with diabetes. Therefore, we believe that our results are of great general interest to a broad audience, including patients and patient organizations, the medical community, academia, the life science industry and the public.

Investigating microRNAs to Explain the Link between Cholesterol Metabolism and NAFLD in Humans: A Systematic Review.

Non-Alcoholic Fatty Liver Disease (NAFLD) is characterized by hepatic free cholesterol accumulation. In addition, microRNAs (miRNAs) might be involved in NAFLD development. Therefore, we systematically reviewed the literature to examine the link between miRNAs and cholesterol metabolism in NAFLD. Nineteen studies were retrieved by a systematic search in September 2022. From these papers, we evaluated associations between 13 miRNAs with NAFLD and cholesterol metabolism. Additionally, their diagnostic potential was examined. Four miRNAs (miR122, 34a, 132 and 21) were associated with cholesterol metabolism and markers for NAFLD. MiR122 was upregulated in serum of NAFLD patients, increased with disease severity and correlated with HDL-C, TAG, VLDL-C, AST, ALT, ALP, lobular inflammation, hepatocellular ballooning and NAFLD score. Serum and hepatic levels also correlated. Serum and hepatic miR34a levels were increased in NAFLD, and correlated with VLDL-C and TAG. Serum miR379 was also higher in NAFLD, especially in early stages, while miR21 gave ambiguous results. The diagnostic properties of these miRNAs were comparable to those of existing biomarkers. However, serum miR122 levels appeared to be elevated before increases in ALT and AST were evident. In conclusion, miR122, miR34a, miR21 and miR132 may play a role in the development of NAFLD via effects on cholesterol metabolism. Furthermore, it needs to be explored if miRNAs 122, 34a and 379 could be used as part of a panel in addition to established biomarkers in early detection of NAFLD.

Hepatic patatin-like phospholipase domain-containing 3 levels are increased in I148M risk allele carriers and correlate with NAFLD in humans.

In nonalcoholic fatty liver disease (NAFLD) the patatin‐like phospholipase domain‐containing 3 (PNPLA3) rs738409 variant is a contributor. In mice, the Pnpla3 148M variant accumulates on lipid droplets and probably leads to sequestration of a lipase cofactor leading to impaired mobilization of triglycerides. To advance our understanding of the localization and abundance of PNPLA3 protein in humans, we used liver biopsies from patients with NAFLD to investigate the link to NAFLD and the PNPLA3 148M genotype. We experimentally qualified an antibody against human PNPLA3. Hepatic PNPLA3 protein fractional area and localization were determined by immunohistochemistry in biopsies from a well‐characterized NAFLD cohort of 67 patients. Potential differences in hepatic PNPLA3 protein levels among patients related to degree of steatosis, lobular inflammation, ballooning, and fibrosis, and PNPLA3 I148M gene variants were assessed. Immunohistochemistry staining in biopsies from patients with NAFLD showed that hepatic PNPLA3 protein was predominantly localized to the membranes of small and large lipid droplets in hepatocytes. PNPLA3 protein levels correlated strongly with steatosis grade (p = 0.000027) and were also significantly higher in patients with lobular inflammation (p = 0.009), ballooning (p = 0.022), and significant fibrosis (stage 2–4, p = 0.014). In addition, PNPLA3 levels were higher in PNPLA3 rs738409 148M (CG, GG) risk allele carriers compared to 148I (CC) nonrisk allele carriers (p = 0.0029). Conclusion: PNPLA3 protein levels were associated with increased hepatic lipid content and disease severity in patients with NAFLD and were higher in PNPLA3 rs738409 (148M) risk allele carriers. Our hypothesis that increased hepatic levels of PNPLA3 may be part of the pathophysiological mechanism of NAFLD is supported.

The Effects of Probiotic Supplementation on Glycemic index, Lipid Profiles and Inflammatory cytokines in NAFLD Patients: A Protocol for a Systematic Review and Meta-Analysis

Background: Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver disorders worldwide. In an aggressive type, non-alcoholic steatohepatitis (NASH) might lead to cirrhosis and hepatocellular carcinoma progression. Currently, there is no certified drug applied to treat NASH. Human studies have demonstrated the beneficial effects of probiotics supplementation in NAFLD. Due to the lack of appropriate studies and the emerging requirements for further illustration over the effects of probiotics on the treatment of NAFLD and NASH-related disorders in humans, in this study, we seek to evaluate this matter often papered over. Methods: We will search PubMed, EMBASE, Cochrane Library, and Web of Science from inception to February 2021. Search terms are keywords and medical subject headings related to NAFLD, probiotics, glycemic indexes, inflammation, and dyslipidemia. 2 researchers will determine the search strategy after several pre-searches. The Glycemic outcomes include glycated hemoglobin, fasting blood glucose, fasting insulin, homeostasis model assessment of insulin resistance. The lipidomic outcomes include differences in High-density lipoprotein, Low-density lipoprotein, Total triglyceride, Total cholesterol. The Inflammatory outcomes include differences in IL6, IL1β, TNFα, CRP. The meta-analysis will be performed using END NOTE and STATA. Results: Our study will systematically evaluate the effectiveness and safety of probiotics supplementation in NAFLD patients. Conclusion: This study’s results will give the proof for probiotics supplements in NAFLD treatment and provide an evidence for clinical treatment.

Lipid balance must be just right to prevent development of severe liver damage.

Nonalcoholic fatty liver disease (NAFLD) is a major health concern that often associates with obesity and diabetes. Fatty liver is usually a benign condition, yet a fraction of individuals progress to severe forms of liver damage, including nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). Elevated sterol regulatory element–binding protein–driven (SREBP-driven) hepatocyte lipid synthesis is associated with NAFLD in humans and mice. In this issue of the JCI, Kawamura, Matsushita, et al. evaluated the role of SREBP-dependent lipid synthesis in the development of NAFLD, NASH, and HCC in the phosphatase and tensin homolog–knockout (PTEN-knockout) NASH model. Deletion of the gene encoding SREBP cleavage–activating protein (SCAP) from the liver resulted in decreased hepatic lipids, as expected. However, SCAP deletion accelerated progression to more severe liver damage, including NASH and HCC. This study provides a note of caution for those pursuing de novo fat biosynthesis as a therapeutic intervention in human NASH.

Metabolic and Cardiac Manifestations in a Mouse Model of Genetic Mitochondrial Hepatopathy Without Obesity: Evidence for a Sexual Dimorphism

ObjectiveIn non‐alcoholic fatty liver disease (NAFLD), liver mitochondrial dysfunction plays an important role in the development of cardiac abnormalities independent of obesity per se. However, the mechanisms underlying the development of these abnormalities, and whether these are affected by sex remain unclear. In the present study, we sought to address this question using a mouse model of hepatic mitochondrial deficiency caused by loss of Lrpprc (H‐Lrpprc‐/‐) as these mice develop microvesicular steatosis and a NAFLD lipidomic‐like profile without obesity.HypothesisOur working hypothesis is that metabolic defects in the liver would trigger metabolic and functional abnormalities in the heart in a sex‐dependent manner.MethodsDetailed phenotyping experiments were performed in male and female H‐Lrpprc‐/‐mice and their controls at 14 weeks of age. Glucose metabolism was monitored by blood glucose as well as insulin, and glucose tolerance tests (ITT, OGTT). Cardiac manifestations were studied using molecular (qPCR), lipidomic (mass spectrometry) and functional (oximetry on isolated mitochondria, intraventricular pressures by Millar probe) analyses.ResultsGenetic inactivation of Lrpprc resulted in an >60% reduction of LRPPRC protein content in both males and females, which resulted in comparable structural liver abnormalities. In contrast, the resulting metabolic and cardiac functional changes displayed a marked sexual dimorphism. Lrpprc deficiency in the liver was associated with fasting hypoglycemia and increased insulin sensitivity in both sexes, but more so in males. Lrpprc deficiency was also associated with a remodeling of specific markers of mitochondrial function exclusively in the female myocardium. This included 1) reduced expression of gene markers for mitochondrial biogenesis (Tfam), fusion (Mfn1‐2), and fatty acid (FA) utilization and oxidation (Pparα, Cd36, Cpt1b, Cpt2, Vlcad, Lcad, Mcad), 2) impairment of FA‐dependent mitochondrial respiration, and 3) increased cardiac triglyceride levels. Paradoxically, cardiac function was preserved in females, while males displayed mild diastolic dysfunction as evidenced by increased early and late diastolic pressures (0.29 and 2.39 fold vs. male wild type respectively) amongst other parameters.ConclusionCollectively, these results indicate that metabolic defects in the liver can result in significant sex‐dependent abnormalities that affect both the mitochondrial/metabolic phenotype and contractile function independent of obesity. This experimental model may prove useful to better understand the mechanisms underlying the sex‐related variability in the progression of lean NAFLD in humans.

Chicory polysaccharides alleviate high-fat diet-induced non-alcoholic fatty liver disease via alteration of lipid metabolism- and inflammation-related gene expression

Administration of chicory polysaccharides (CP) can modify lipid metabolism, improve dyslipidemia, and reduce liver inflammation, all of which may help alleviate non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanisms remain unclear. This study aimed to gain further understanding of the potential molecular mechanisms that mediate the protective effects of CP against NAFLD via transcriptomic and metabolomic analyses. Hepatic RNA-sequencing analysis demonstrated that long-term intake of CP restored expression of lipid metabolism-related genes Xbp1, Insig2, and Cth in NAFLD rats, thereby inhibiting de novo lipogenesis. Moreover, CP consumption restored expression levels of genes involved in pro-inflammatory responses, such as Irf1. In addition, metabolic data confirmed that CP treatment increased levels of L-palmitoylcarnitine and hexadecanoyl-CoA, implying that CP administration can promote hepatic fatty acid β-oxidation. The present results demonstrate the underlying mechanisms of CP in high-fat diet-induced NAFLD rats and suggest that CP treatment might provide a dietary therapeutic tool for the treatment of NAFLD in humans.

Effects of exercise on NAFLD using non-targeted metabolomics in adipose tissue, plasma, urine, and stool

The mechanisms by which exercise benefits patients with non-alcoholic fatty liver disease (NAFLD), the most common liver disease worldwide, remain poorly understood. A non-targeted liquid chromatography-mass spectrometry (LC–MS)-based metabolomics analysis was used to identify metabolic changes associated with NAFLD in humans upon exercise intervention (without diet change) across four different sample types—adipose tissue (AT), plasma, urine, and stool. Altogether, 46 subjects with NAFLD participated in this randomized controlled intervention study. The intervention group (n = 21) performed high-intensity interval training (HIIT) for 12 weeks while the control group (n = 25) kept their sedentary lifestyle. The participants' clinical parameters and metabolic profiles were compared between baseline and endpoint. HIIT significantly decreased fasting plasma glucose concentration (p = 0.027) and waist circumference (p = 0.028); and increased maximum oxygen consumption rate and maximum achieved workload (p < 0.001). HIIT resulted in sample-type-specific metabolite changes, including accumulation of amino acids and their derivatives in AT and plasma, while decreasing in urine and stool. Moreover, many of the metabolite level changes especially in the AT were correlated with the clinical parameters monitored during the intervention. In addition, certain lipids increased in plasma and decreased in the stool. Glyco-conjugated bile acids decreased in AT and urine. The 12-week HIIT exercise intervention has beneficial ameliorating effects in NAFLD subjects on a whole-body level, even without dietary changes and weight loss. The metabolomics analysis applied to the four different sample matrices provided an overall view on several metabolic pathways that had tissue-type specific changes after HIIT intervention in subjects with NAFLD. The results highlight especially the role of AT in responding to the HIIT challenge, and suggest that altered amino acid metabolism in AT might play a critical role in e.g. improving fasting plasma glucose concentration.Trial registration ClinicalTrials.gov (NCT03995056).

Amino Acid and Fatty Acid Metabolism Disorders Trigger Oxidative Stress and Inflammatory Response in Excessive Dietary Valine-Induced NAFLD of Laying Hens.

Non-alcoholic fatty liver disease (NAFLD) is a chronic and metabolic liver disease and commonly occurs in humans with obesity and type 2 diabetes mellitus (T2DM); such a condition also exists in animals such as rodents and laying hens. Since the pathogenesis of fatty liver hemorrhagic syndrome (FLHS) of laying hens is similar to human NAFLD, hen's FLHS is commonly selected as a study model of NAFLD. Altered circulating amino acids, particularly elevated branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs), are consistently reported in patients with NAFLD and T2DM. How long-term dietary individual BCAA, such as valine, impacts amino acid and fatty acid metabolism remains unknown. In this study, we demonstrated that when laying hens are fed with dietary valine at different levels (59, 0.64, 0.69, 0.74, and 0.79%) in a feeding trial that lasted for 8 weeks, long-term exposure to excessive valine diets at 0.74 and 0.79% levels could induce amino acid imbalance, impair amino acid metabolism, increase fatty acid synthesis, and inhibit fatty acid utilization. Long-term intake of excessive dietary valine could result in impaired amino acid metabolism via inhibiting C/EBP-β/asparagine synthetase (Asns). This process is mediated by downregulating the general control nonderepressible-eukaryotic initiation factor 2α- activating transcription factor (GCN2-eIF2α-ATF4) pathway and elevating corresponding circulating BCAAs and AAAs levels, which could ultimately result in amino acid imbalance. High levels of dietary valine stimulated lipid deposition by suppressing the GCN2-eIF2α-ATF4-fibroblast growth factor-19 (FGF19)-target of rapamycin complex 1 (TORC1) signaling pathway to promote fatty acid synthesis, repress fatty acid utilization, and eventually accelerate the development of NAFLD. The Spearman correlation analysis revealed that circulating amino acid imbalance is significantly associated with fatty acid metabolism disorder and enhanced oxidative stress. The inhibition of the GCN2-TORC1 pathway induced autophagy suppression to trigger liver oxidative stress and inflammatory response. In conclusion, our results revealed the adverse metabolic response to excessive dietary valine mediated by amino acid and fatty acid metabolism disorders. This study also suggested reducing dietary valine as a novel approach to preventing and treating NAFLD in humans and FLHS in laying hens.

A Novel 2-Hit Zebrafish Model to Study Early Pathogenesis of Non-Alcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in adults. NAFLD progresses from benign liver fat accumulation to liver inflammation and cirrhosis, and ultimately leads to liver failure. Although several rodent models have been established for studying NAFLD, they have limitations that include cost, speed of disease development, key dissimilarities, and poor amenability to pharmacological screens. Here, we present a novel 2-hit zebrafish model to replicate aspects of NAFLD pathogenesis. We fed zebrafish larvae a high-fat diet (HFD) to drive liver fat accumulation (first hit). Next, we exacerbated liver-specific inflammation using a transgenic line (fabp10-CETI-PIC3) that induces the expression of proinflammatory cytokines following induction with doxycycline (second hit). These hits promoted fat accumulation and liver inflammation, as demonstrated by the high expression of inflammatory cytokines, macrophage infiltration, stress induction, and hepatic lipid droplet accumulation. Furthermore, zebrafish in this paradigm showed deranged glucose metabolism. To validate a small-molecule screening approach, we treated HFD-fed fish with pioglitazone, a drug shown to be beneficial for NAFLD in humans, and measured a sharp reduction in liver lipid accumulation. These results demonstrate new utility for zebrafish in modeling early NAFLD pathogenesis and demonstrate their feasibility for in vivo screening of new pharmacological interventions.

Possible etiological factors related with fatty liver diseases other than alcohol

Non-alcoholic Fatty liver disease (NAFLD) is an ailment that is associated with various causative factors other than alcohol consumption. It affects a substantial number of individuals both young and old irrespective of sex around the globe and its incidence is increasing/rises globally. The data was collected by searching various websites, consulting reports and analysed the data with respect to possible causative factors related to NAFLD in humans. The data available indicated that several factors such as drug addiction/abuse, unhealthy dietary practices, lifestyle habits, diabetic, metabolic disorders, obesity, sedentary lifestyles etc. might be related to non-alcoholic fatty liver disorders in human or exaggerate the NAFLD. Thus, there is a necessity to prevent exposure to such chemicals and/or factors to reduce or prevent this disease and there is also a necessity for an awareness program about the causative factors of NAFLD among the community which could be useful in prevention/control of the ailment. Further, some sort of regular physical exercise, activity and excess weight loss might be useful to check/ control the occurrence/ progression of NAFLD. NAFLD can be prevented/ reduced/ stopped by adaptation of healthy lifestyles in day-to-day life, regular exercise to reduce the weight, and adoption of these in life may be useful in management/ control of disease. Keywords: Fatty liver disease; Non-alcoholic liver disease; Non-alcoholic steatohepatitis; Cirrhosis; Metabolic disorders.

Stearoyl-CoA desaturase 1: A potential target for non-alcoholic fatty liver disease?-perspective on emerging experimental evidence.

Non-alcoholic fatty liver disease (NAFLD) is a progressive disease and one of the leading causes of death. An unnamed disease has become a global epidemic disease of public health concern. This spectrum of diseases manifests itself with initial accumulation of excessive triglycerides (due to de novo lipogenesis) in the hepatocytes, leading to simple steatosis. Although its aetiology is multi-factorial, lifestyle changes (diet and physical activity) are considered to be the key thriving factors. In this context, high fructose consumption is associated with an increased risk for developing NAFLD in humans, while high-fructose feeding to experimental animals results in hepatic steatosis and non-alcoholic steatohepatitis, by increasing hepatic lipogenesis. Among several lipogenic genes, the endoplasmic reticulum-bound stearoyl-CoA desaturase 1 (SCD1) is the key determinant of triglycerides biosynthesis pathway, by providing monounsaturated fatty acids, through the incorporation of a double bond at the delta-9 position of saturated fatty acids, specifically, palmitic (C16:0) and stearic (C18:0) acids, yielding palmitoleic (C16:1) and oleic (C18:1) acids, respectively. Various experimental studies involving SCD1 gene knockout and diet-induced rodent models have demonstrated that SCD1 plays a key role in the development of NAFLD, by modulating hepatic lipogenesis and thus triglyceride accumulation in the liver. Several pharmacological and dietary intervention studies have shown the benefits of inhibiting hepatic SCD1 in the pathogenesis of NAFLD. In this review, we give an overview of SCD1 in NAFLD, based on the current experimental evidence and the translational applicability of SCD1 inhibition in human NAFLD conditions, besides discussing the limitations and way-forward.

Integrated Liver and Plasma Proteomics in Obese Mice Reveals Complex Metabolic Regulation

Obesity leads to the development of nonalcoholic fatty liver disease (NAFLD) and associated alterations to the plasma proteome. To elucidate the underlying changes associated with obesity, we performed liquid chromatography–tandem mass spectrometry in the liver and plasma of obese leptin-deficient ob/ob mice and integrated these data with publicly available transcriptomic and proteomic datasets of obesity and metabolic diseases in preclinical and clinical cohorts. We quantified 7173 and 555 proteins in the liver and plasma proteomes, respectively. The abundance of proteins related to fatty acid metabolism were increased, alongside peroxisomal proliferation in ob/ob liver. Putatively secreted proteins and the secretory machinery were also dysregulated in the liver, which was mirrored by a substantial alteration of the plasma proteome. Greater than 50% of the plasma proteins were differentially regulated, including NAFLD biomarkers, lipoproteins, the 20S proteasome, and the complement and coagulation cascades of the immune system. Integration of the liver and plasma proteomes identified proteins that were concomitantly regulated in the liver and plasma in obesity, suggesting that the systemic abundance of these plasma proteins is regulated by secretion from the liver. Many of these proteins are systemically regulated during type 2 diabetes and/or NAFLD in humans, indicating the clinical importance of liver–plasma cross talk and the relevance of our investigations in ob/ob mice. Together, these analyses yield a comprehensive insight into obesity and provide an extensive resource for obesity research in a prevailing model organism.

Macrophage scavenger receptor 1 mediates lipid-induced inflammation in non-alcoholic fatty liver disease

Obesity-associated inflammation is a key player in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the role of macrophage scavenger receptor 1 (MSR1, CD204) remains incompletely understood. A total of 170 NAFLD liver biopsies were processed for transcriptomic analysis and correlated with clinicopathological features. Msr1-/- and wild-type mice were subjected to a 16-week high-fat and high-cholesterol diet. Mice and exvivo human liver slices were treated with a monoclonal antibody against MSR1. Genetic susceptibility was assessed using genome-wide association study data from 1,483 patients with NAFLD and 430,101 participants of the UK Biobank. MSR1 expression was associated with the occurrence of hepatic lipid-laden foamy macrophages and correlated with the degree of steatosis and steatohepatitis in patients with NAFLD. Mice lacking Msr1 were protected against diet-induced metabolic disorder, showing fewer hepatic foamy macrophages, less hepatic inflammation, improved dyslipidaemia and glucose tolerance, and altered hepatic lipid metabolism. Upon induction by saturated fatty acids, MSR1 induced a pro-inflammatory response via the JNK signalling pathway. Invitro blockade of the receptor prevented the accumulation of lipids in primary macrophages which inhibited the switch towards a pro-inflammatory phenotype and the release of cytokines such as TNF-ɑ. Targeting MSR1 using monoclonal antibody therapy in an obesity-associated NAFLD mouse model and human liver slices resulted in the prevention of foamy macrophage formation and inflammation. Moreover, we identified that rs41505344, a polymorphism in the upstream transcriptional region of MSR1, was associated with altered serum triglycerides and aspartate aminotransferase levels in a cohort of over 400,000 patients. Taken together, our data suggest that MSR1 plays a critical role in lipid-induced inflammation and could thus be a potential therapeutic target for the treatment of NAFLD. Non-alcoholic fatty liver disease (NAFLD) is a chronic disease primarily caused by excessive consumption of fat and sugar combined with a lack of exercise or a sedentary lifestyle. Herein, we show that the macrophage scavenger receptor MSR1, an innate immune receptor, mediates lipid uptake and accumulation in Kupffer cells, resulting in liver inflammation and thereby promoting the progression of NAFLD in humans and mice.