Nutritional therapy for non-alcoholic fatty liver disease Paola Dongiovanni, Claudia Lanti, Patrizia Riso, Luca Valenti PII: DOI: Reference:
S0955-2863(15)00225-9 doi: 10.1016/j.jnutbio.2015.08.024 JNB 7438
To appear in:
The Journal of Nutritional Biochemistry
Received date: Revised date: Accepted date:
21 July 2015 26 August 2015 26 August 2015
Please cite this article as: Dongiovanni Paola, Lanti Claudia, Riso Patrizia, Valenti Luca, Nutritional therapy for non-alcoholic fatty liver disease, The Journal of Nutritional Biochemistry (2015), doi: 10.1016/j.jnutbio.2015.08.024
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Nutritional therapy for non-alcoholic fatty liver disease Paola Dongiovanni1, Claudia Lanti2, Patrizia Riso2*, Luca Valenti1,3 Internal Medicine and Metabolic Diseases, Fondazione IRCCS Ca’ Granda Ospedale
T
1
2
RI P
Maggiore Policlinico, 20122 Milano, Italy
Department of Food, Environmental and Nutritional Sciences (DeFENS), Division of
3
SC
Human Nutrition, Università degli Studi di Milano, 20133 Milano, Italy Department of Pathophysiology and Transplantation (DEPT), Università degli Studi di
MA
NU
Milano, 20122 Milano, Italy
Corresponding author
ED
Patrizia Riso - Division of Human Nutrition, Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, 20133 Milano, Italy
tel: + 39 02 50316726
AC
CE
fax: + 39 02 50316721
PT
e-mail:
[email protected] 1
ACCEPTED MANUSCRIPT Abstract Following the epidemics of obesity, nonalcoholic fatty liver disease (NAFLD) has become the leading cause of liver disease in Western countries. NAFLD is the hepatic
T
manifestation of metabolic syndrome and may progress to cirrhosis and hepatocellular
RI P
carcinoma. To date, there are no approved drugs for the treatment of NAFLD and the main clinical recommendation is lifestyle modification, including increase of physical
SC
activity and the adoption of a healthy eating behavior. In this regard, studies aimed to elucidate the effect of dietary interventions and the mechanisms of action of specific food
NU
bioactives are urgently needed.
The present review try to summarize the most recent data evidencing the effects of
MA
nutrients and dietary bioactive compounds intake (i.e. long-chain PUFA, vitamin E, vitamin D, minerals and polyphenols) on the modulation of molecular mechanisms leading to fat accumulation, oxidative stress, inflammation and liver fibrosis in NAFLD
PT
ED
patients.
Keywords: Nonalcoholic fatty liver disease (NAFLD), food bioactives, molecular
AC
CE
mechanisms, in vitro studies, animal models, clinical trials
Running title: Mechanisms of food bioactives in NAFLD
2
ACCEPTED MANUSCRIPT 1. Introduction Nonalcoholic fatty liver disease (NAFLD), also known as hepatic steatosis, is defined by liver fat deposition in the absence of excessive alcohol intake [1]. Following the
T
epidemics of obesity, NAFLD has become the leading cause of liver disease (prevalence
RI P
20-34%) [2, 3] and it is epidemiologically associated with the metabolic syndrome and insulin resistance (IR) [4-6]. NAFLD is an umbrella term used to described a histological
SC
spectrum ranging from simple steatosis, defined by a concentration of hepatic triglycerides (TG) exceeding 5% of liver weight, to nonalcoholic steatohepatitis (NASH)
NU
characterized by hepatocellular damage, lobular necroinflammation and fibrogenesis [7, 8]. NASH may evolve to cirrhosis and then to end stage liver failure or hepatocellular
MA
carcinoma [9, 10]. Genetic variants plays a major role in disease predisposition [11] by interacting with nutritional and other environmental factors, typically hypercaloric diet and lack of physical activity. To date, there are no approved drugs for the treatment of
ED
NAFLD and the main clinical recommendation as an initial step is lifestyle modification. Systematic reviews on the role of specific nutrients and phytochemicals on NAFLD and
PT
related outcomes have recently been published [12, 13]. In this review, we will specifically focus on the mechanism by which selected macro- / micro-nutrients and food
CE
bioactives exert a beneficial effect on the hepatic outcomes of NAFLD.
AC
2. Pathophysiology of NAFLD Fatty liver results from an unbalance between TG accumulation and removal and represents the safest way to store free fatty acids (FFAs) in the liver [6, 14]. Excess hepatocellular TG derives from several sources including dietary fatty acids, increased peripheral lipolysis due to adipose tissue IR and elevated hepatic de novo lipogenesis due to hyperinsulinemia. Indeed, the major determinant of NAFLD is systemic insulin resistance [4, 15]. Reduction of lipid secretion through very low-density lipoproteins (VLDL) and a decreased fatty acids oxidation are also involved in hepatic fat accumulation [5]. The development of NASH has been explained by the occurrence of multiple so-called “second-hits” leading to the activation of inflammation in the context of hepatic steatosis [16, 17]. The initial hit leading to the development of fatty liver, renders hepatocytes
3
ACCEPTED MANUSCRIPT susceptible to other multiple hepatotoxic insults including: a) peroxidation, b) oxidative stress secondary to free radicals produced during - and omega- oxidation of FFAs, c) inflammation triggered by endotoxin engaging Toll-like receptor-4 in Kupffer cells and
T
hepatocytes due to increased intestinal permeability, d) qualitative and quantitative
RI P
changes in gut microbiota [18, 19], e) hepatic stellate cells activation, f) mitochondrial dysfunction. All these conditions lead in the end to inflammation, cellular damage, and
SC
activation of fibrogenesis [20].
NU
3. NAFLD management
The usual management of NAFLD includes lifestyle counseling to achieve a gradual
MA
weight reduction and an increase in physical activity. Patients are encouraged to lose ≥8% of their body weight. An intensive lifestyle intervention focused on diet, exercise and behavior modification with a goal of 7-10% weight reduction leads to significant
ED
improvement in liver histology in patients with NASH [21]. Indeed, weight loss improves steatosis [22], reduces hepatic inflammation and hepatocellular injury [21, 23], and
PT
improves cardiovascular risk profile. However, weight loss through energy restriction is difficult to achieve and sustain [24]. Physical activity and exercise also effectively
CE
decrease steatosis. Cross-sectional and prospective studies have shown that physical activity decreases intrahepatic lipids [25, 26]. Both aerobic and resistant exercises have
AC
been shown to improve liver function, independently of weight loss [27-29]. In addition to total energy intake, the composition of the diet also affects the metabolic and endocrine functions and overall energy balance [30]. Most recommendations encourage the consumption of diets rich in fruits and vegetables for prevention of chronic disease, and NAFLD is not exception. Such diets would provide significant amount of bioactive components with known beneficial effects due in part to their antiinflammatory properties [31]. General recommendations include a reduction in the intakes of total fat, saturated fatty acids (SFAs), trans fatty acids, and fructose. Indeed, high fructose intake has been associated with increased risk of NAFLD and liver damage [32-34]. Dietary fructose (consumed in the form of soft drinks) has been implicated in the pathogenesis of NAFLD [35]. Mice with ad libitum access to fructose solution showed significantly higher levels 4
ACCEPTED MANUSCRIPT of hepatic lipid accumulation, lipid peroxidation and endotoxin levels in the portal blood compared to controls and mice fed with glucose solution [36]. Conversely, an increase in the intakes of polyunsaturated fatty acids (PUFAs) and
RI P
include long-chain n-3 fatty acids to reduce the risk of NAFLD.
T
monounsaturated fatty acids (MUFAs) is advised. Moreover, there is recommendation to
A few trials were conducted to evaluate the impact of specific dietary patterns on liver
SC
damage in patients with NAFLD. In this regard, Mediterranean diet led to similar weight loss, but induced a more marked reduction of liver enzymes and of insulin resistance
NU
compared to a low-fat high carbohydrate diet [30]. Indeed, the diet of patients with NASH is usually enriched in saturated fat and cholesterol, whereas it is poor in
MA
polyunsaturated fat, fibers and antioxidant vitamins C and E [31]. In addition to an imbalance in fat intake, higher odds of inflammation were associated with higher carbohydrate intake in NASH patients [37].
ED
Apart from lifestyle modification, statins (lipid-lowering drugs), glitazones (insulin sensitizers), antioxidants and metformin have been used as therapies for NAFLD [38,
PT
39]. Glitazones improve steatosis at the expense of an increase of weight and the longterm safety of their utilization is still not clear. Randomized clinical trials with
CE
antioxidants (Vitamin E and N-acetylcysteine) have given conflicting results, suggesting that their effect may be different depending on age, dosage and lifestyle modifications
AC
[39]. A few studies have tested metformin in nondiabetic patients, but with inconsistent results [40, 41].
All these findings emphasize the difficulties to achieve success in NAFLD clinical setting and attract attention to the importance of alternative approaches for the prevention of liver damage progression in NAFLD.
4. Promising food bioactives In this review, we will focus our attention on the most promising bioactive compounds studied in the last years for their possible beneficial effects on the prevention and treatment of NAFLD. We have selected the compounds that have been most investigated in in vitro and in vivo studies, especially if there is accompanying evidence of efficacy clinical trials. Evaluated bioactives and their putative mechanisms of action are listed in
5
ACCEPTED MANUSCRIPT table 1. In the following paragraphs, we will review the most important evidence supporting their activity, and discuss the evidence supporting the mechanisms of their
T
beneficial effects.
RI P
4.1 Omega-3 PUFAs
Long-chain omega-3 (n-3) fatty acids have been proposed as potential treatment for
SC
NAFLD. These fatty acids are present in large quantities in fish oil, flaxseed and some nuts. They can be synthesized in vivo by the human body from -linolenic acid and
NU
mainly occur as eicosapentaenoic acid (EPA) and decosahexaenoic acid (DHA), which are both anti-inflammatory. Omega-3 PUFA supplementation ameliorates hepatic
MA
steatosis in animal models and in human studies [42, 43]. Clinical trials, investigating the therapeutic effect of omega-3 in patients with NAFLD suggested beneficial effects on hepatic fat accumulation, liver function tests, fasting
ED
blood glucose and serum triglycerides [44-46]. A randomized, double-blind, placebocontrolled trial of DHA, EPA, or DHA+EPA supplementation has shown that EPA
PT
enrichment in the peripheral blood is linearly associated with decreased liver fat percentage in patients with NAFLD [47]. Two controlled clinical trials performed in
CE
NAFLD children also demonstrated that omega-3 supplementation for 6-24 months reduced hepatic steatosis, IR, circulating TG and ALT levels [48, 49]. Moreover, a recent
AC
meta-analysis confirmed the beneficial effect of omega-3 on steatosis [50]. Conversely, evidence about necroinflammation and fibrosis progression in NASH after omega-3 supplementation is still lacking [51]. However, clinical studies are ongoing, and there is a strong mechanistic rationale for supporting such an effect. Indeed, DHA specifically binds with high affinity to the G protein-coupled receptor 120 (GPR120) that mediates potent insulin sensitizing effects in vivo by repressing macrophage-induced tissue inflammation [52]. In pediatric NAFLD, DHA treatment reduced liver damage, the number of inflammatory macrophages and increased GPR120 expression in hepatocytes. Modulation of GPR120 plays a key role in the regulation of the cell-to-cell cross-talk that drives inflammatory response, hepatic progenitor cell activation and hepatocyte survival [53, 54].
6
ACCEPTED MANUSCRIPT In HepG2 hepatoma cells, the expression of fatty acid synthase (FAS) and sterol regulatory element binding protein 1c (SREBPC1) involved in de novo lipogenesis, were suppressed by DHA or EPA supplementation [55]. Moreover, PUFA supplementation
T
modulated the antioxidant defense increasing SOD, GST and GPX activity [56].
RI P
In high fat diet (HFD) fed mice, dietary intake of EPA reduced steatosis by reducing hepatic cholesterol, TG and FFAs [57]. Moreover, EPA intake seems to abrogate HFD-
SC
induced modulation in genes involved in hepatocellular lipid metabolism. These include upregulation of Srebp-1c, which induces the lipogenic program, FAS and acyl-
NU
coenzymeA-carboxylase-1 (ACC1) and the decrease of expression of carnytoil-palmitatetransporter-1 (CPT1), which transports FFAs to the mitochondria and promote -
MA
oxidation [58]. Several studies have demonstrated that EPA decreases steatosis and fibrosis progression by reducing TG synthesis and the expression of fibrogenic genes, and indeed it represents an established treatment for hypertriglyceridemia [59, 60]. EPA
ED
supplementation is associated with decreased hepatic ROS production and activation of AMP-activated protein kinase (AMPK) and Peroxisome-proliferator activated receptor-
PT
(PPARwhich stimulates lipid catabolism. In mice fed HFD and steatogenic choline deficient diets, DHA supplementation reduced hepatic steatosis, inflammation, fibrosis
CE
and lipid peroxidation [61, 62]. Increased activity of superoxide dismutase (SOD) and downregulation of Srebp-1c seem to account for the inhibitory effect of DHA. DHA was
AC
also found to ameliorate hepatic steatosis through the downregulation of other nuclear receptors involved in TG synthesis such as Peroxisome proliferator activated receptor (PPAR and Retionid X receptor (RXR). Several unsaturated fatty acids, including DHA, have the capacity to specifically bind and activate the RXR, since PUFAs have been shown to fit into the ligand-binding pocket of the RXR crystal [63]. Finally, both DHA and EPA are able to restore adiponectin levels which contribute to improve hepatic insulin sensitivity [64]. In summary, omega-3 fatty acids may be a possible therapy for NAFLD. They have several potential mechanisms of action, the most relevant is the regulation of hepatic gene expression, thereby switching intracellular metabolism from lipogenesis and storage to fatty acid oxidation and catabolism, and activation of anti-inflammatory pathways.
7
ACCEPTED MANUSCRIPT 4.2 Vitamin E Vitamin E is the generic name for eight lipophilic isoforms: four tocopherols (α, β, γ, δToc) and four tocotrienols (α, β, γ, δ-T3). Toc is present in a variety of foods as vegetable
T
oil and nuts whereas T3-containing foods are limited as palm oil and cereal grains [65].
RI P
Both Toc and T3 have a chroman ring structure with an isoprene side chain. Toc have a saturated isoprene side chain, conversely, T3 have three unsaturated bonds in the side
SC
chain [66]. Although all forms of Vitamin E have an antioxidant effect on lipid peroxidation, the most important for human health are α and γ-Toc due to their dietary
NU
abundance. Despite all the isoforms reach the liver, only α-Toc binds α-tocopherol transfer protein (α-TTP) that is located in the cytosol of hepatocytes. Afterwards, it is
MA
incorporated into nascent VLDLs and released into the blood circulation [67]. Since oxidative stress is a major feature of NASH [68-70], vitamin E has been investigated in this condition. Clinical trials with vitamin E supplementation in NASH patients yielded
Steatohepatitis)
trial,
ED
promising results. In the PIVENS (Pioglitazone, Vitamin E or Placebo for Non-alcoholic high
dose
Vitamin
E
(800
IU/day)
reduced
hepatic
PT
necroinflammation and facilitated resolution of NASH, as compared to placebo, but there was not an improvement in fibrosis score [71]. A combination of atorvastatin, vitamin C
CE
and high dose vitamin E for 4 years, reduced hepatic steatosis (by 71%) in subjects with NAFLD [72]. In another study, twelve patients with NASH and 10 with NAFLD received
AC
300 mg/day α-toc for 1 year. Steatosis, inflammation and fibrosis were improved after αtoc treatment in NASH patient [73]. Few data are available on the effect of antioxidants/vit E in paediatric NAFLD. Diet and physical exercise in biopsy-proven NAFLD children led to a significant improvement of liver function and glucose metabolism beyond any antioxidant therapy [74]. In the TONIC (Treatment of NAFLD in Children) trial, Vitamin E improved hepatocellular ballooning and resolved NASH more frequently compared to placebo [75]. However, it should be noted that a meta-analysis of randomized controlled trials showed that high-dosage vitamin E is associated with an increase in total mortality, and vitamin E supplementation has been associated with increased risk of haemorrhagic stroke and prostate cancer [76]. Vitamin E may have pro-oxidant effect at high doses disrupting the natural balance of antioxidant systems and increasing vulnerability to oxidative damage.
8
ACCEPTED MANUSCRIPT High-dose vitamin E supplements (> or =400 IU/d) have been reported to increase allcause mortality suggesting that the dose-dependent effect of vitamin E should be carefully considered [77].
T
The mechanism of action is not limited to its antioxidant properties, determining reduced
RI P
mitochondrial damage, but also to the indirect influence on other pathways as highlighted in in vitro and in vivo studies.
SC
Cultured human fibroblast and rat hepatic stellate cells treated with vitamin E showed a reduction of lipid peroxidation and the inhibition of collagen gene transcription [78, 79].
NU
In addition, T3 supplementation inhibited TG accumulation in human and mouse hepatoma cells through the down- and up-regulation of genes involved in lipogenesis and
MA
-oxidation respectively. In particular, γδT3 reduced Srebp2 and Apoliprotein B100 (ApoB100) enhancing VLDL efflux [80]. The uptake of fatty acids in the liver is crucial for the establishment and development of NAFLD. In a recent study, the expression of
ED
the fatty acid carrier CD36 was reduced by both α Toc and atorvastatin [72, 81]. In rats fed HFD, vitamin E reduced oxidative stress, protein nitrosylation and tissue TNF-
PT
alpha levels [82]. A 5-week dietary supplementation with either α- or γ-Toc in genetically obese Lepob/obmice decreased LPS-triggered lipid peroxidation, inflammation and hepatic
CE
damage [83]. Moreover, vitamin E inhibited hepatic TGF-β1 gene expression and protected against liver fibrosis in rats [84]. The amelioration of steatohepatitis and the
AC
reduction in lipid peroxidation were also observed in mice and rats fed a methionine choline deficient diet [85]. Conversely, in Wistar rats fed methionine choline deficient diet supplemented with vitamin E, despite the reduction of lipid peroxidation, infiltration of inflammatory cells, lipid deposition and fibrosis were not prevented [67]. In conclusion, vitamin E supplementation could be considered a therapeutic tool in NAFLD management. However, the optimal benefit–risk ratio has to be determined for the specific individual.
4.3 Vitamin D Vitamin D refers to a group of fat-soluble secosteroid hormones which are involved in the regulation of mineral and skeletal homeostasis. Vitamin D derives from both dietary sources, such as oily fish (vitamin D2) and from dermal synthesis (Vitamin D3). In the
9
ACCEPTED MANUSCRIPT skin, ultraviolet radiation converts 7-dehydrocholesterol to pre-vitamin D3 and then to vitamin D3. In the liver, vitamin D is metabolized to 25-hydroxyvitamin D [86] or calcidiol. Calcidiol is then transported to the kidney where is further hydroxylated to the
T
active form (1α,25-dihydroxyvitamin D) or calcitriol [87]. The production of calcitriol is
RI P
regulated by hormonal cues (such as parathyroid hormone and FGF-19), and serum calcium and phosphate levels [88].
SC
Besides calcium and bone homeostasis, Vitamin D also regulates cell proliferation and differentiation, and has immunomodulatory, anti-inflammatory and anti-fibrotic
NU
properties. Evidence is accumulating that vitamin D deficiency contributes to the development of IR and NAFLD [86]. This is relevant since up to 55% of adolescents in
MA
the U.S. were reported to be vitamin D deficient [89]. Obese children are more likely to be sedentary with reduced sunlight exposure and often they consume caloric foods low in vitamin content [90, 91]. Moreover, vitamin D levels are related to the histological
ED
severity of steatosis, necroinflammation and fibrosis [87, 92-95]. However, short-term vitamin D supplementation did not consistently improve NAFLD
PT
histological features or dyslipidemia in affected subjects [96], while longer-term supplementation was associated with reduced inflammation and lipid peroxidation [97].
CE
The biological activity of calcitriol is mediated by binding and transactivation of the nuclear Vitamin D receptor (VDR) [98, 99]. In hepatoma cells, VDR directly induces
AC
detoxifying enzymes and regulate bile acid homeostasis [100]. Vitamin D could avoid excessive inflammatory response in hepatic macrophages since these immune cells express both VDR and 1α hydroxylase [101]. Hepatic stellate cells are the main producers of extracellular matrix components playing a pivotal role in liver fibrosis. VDR is expressed in HSCs and orchestrates myofibroblast trans-differentiation and the fibrogenic program. VDR ligands inhibit HSC activation by TGF and abrogate fibrotic gene expression whereas VDR knockout mice spontaneously develop hepatic fibrosis. Mechanistic studies revealed that activation of VDR signalling antagonizes a wide range of TGFβ/SMAD-dependent transcriptional responses on profibrotic genes in HSCs, suggesting that the dynamic VDR/SMAD circuit could represents a possible target for anti-fibrotic therapy [102]. In vivo studies tried to investigate further applications of vitamin D as therapy in NAFLD. In rodents, vitamin D signaling was
10
ACCEPTED MANUSCRIPT involved in maintaining hepatic lipid homeostasis and vitamin D depletion promoted NASH development [103, 104]. On the other hand, Vitamin D supplementation attenuated HFD-induced hepatic steatosis in a dose-dependent manner along with
T
improvement in serum lipid profile, by decreasing lipogenesis and promoting FFAs
RI P
oxidation [105].
Although the potential use of vitamin D in NAFLD has become more intriguing with
SC
preclinical model of steatosis, further studies are necessary to better clarify the biological
NU
activity of vitamin D and the clinical impact of supplementation.
4.4 Polyphenols
MA
Fruits, vegetable and beverages including fruit juices, wine, tea, coffee and chocolate are important sources of bioactive compounds such as polyphenols. Polyphenols are a group of phytochemicals mostly investigated for their potential role in
ED
the prevention and treatment of oxidative stress and inflammation. Polyphenols are secondary metabolites of plants; they are characterized by the presence of at least one
PT
aromatic ring in their structure, linked to different chemical group as phenolic, hydroxyl or carbon groups. They can be classified based on their source, biological function, and
CE
chemical structure.
Polyphenols are generally subdivided in flavonoids and non flavonoids depending on
AC
their chemical structure. Flavonoids are the most abundant in the diet and include flavonols (e.g. quercetin and kaempferol, flavones (eg. luteolin, apigenin), flavan-3-ols (eg. catechins), flavanones (eg. hesperetin, naringenin), isoflavones (eg. genistein), anthocyanidins (i.e. cyanidin, malvidin, pelargonidin, delphinidin, peonidin, petunidin) and proanthocyanidins (i.e. condensed tannins). Non flavonoids are represented by stilbenes, phenolic acids and hydroxycinnamates [106, 107].
Several in vitro and in vivo studies investigated polyphenols properties related to NAFLD despite there are few clinical evidences of the beneficial effect in NAFLD treatment. In a randomized, placebo-controlled, double-blind trial, participants received 250 mL of bayberry juice twice daily for 4 weeks. The consumption of polyphenols-rich bayberry juice reduced the levels of oxidative (i.e. protein carbonyl groups), inflammatory (i.e.
11
ACCEPTED MANUSCRIPT TNFα and interleukin-8) and apoptotic (i.e. tissue polypeptide-specific antigen and cytokeratin-18 fragment M30) biomarkers in young individuals with NAFLD [108]. Another study demonstrated that an Hibiscus sabdariffa L. extract rich in polyphenols
T
(1.43% of flavonoids, 2.5% anthocyanins and 1.7% phenolic acid), administered in
RI P
capsules, was able to decrease body weight, serum FFAs and to improve liver steatosis in overweight subject [109].
SC
It must be considered that flavonoids are a very heterogenic group of compounds with numerous beneficial effects, indeed they could target different pathways possibly
NU
involved in the pathogenesis of liver diseases [110]. First of all, flavonoids could control de novo lipogenesis, inhibiting lipogenic (ACC, SREBP-1, FAS, LXRα) and increasing
MA
lypolitic enzymes (AMPK, PPARα, CPT-1). Secondly, flavonoids are very effective scavengers since they can protect or enhance the endogenous antioxidant defense. Lastly, flavonoids have anti-inflammatory properties inhibiting NFκB pathway [110]. In HepG2
ED
hepatoma cells, polyphenols reduce the activity of hydroxymethilglutaryl-CoA (HMGCoA) lyase [111] and the activity of acyl-coenzyme A diacylglycerol acyltransferase
PT
(DGAT), which catalizes the final step in TG synthesis [112]. In particular, within polyphenols family, quercitin inhibits TAG accumulation and promote cell proliferation
CE
in HepG2, while SOD, GPX and CAT activities are upregulated [113]. Primary rat hepatocytes treated with phenolic fraction show a down-regulation of ACC and
AC
hydroxymethilglutaryl-CoA reductase (HMGCR), regulating cholesterol synthesis, activities [114]. Caffeic acid addition in HepG2 cells induces hepatic lipolysis and reduce hepatic lipogenesis up-regulating AMPK, PPARα and decreasing ACC, SREBP-1 and FAS protein expression [115]. Concerning in vivo studies, the investigation of polyphenols properties have been performed using different poliphenols-rich extracts in heterogeneous animal models. In genetically obese db/db mice, a polyphenol extract reduced the activity of lipogenic enzymes involved in de novo fatty acid biosynthesis [116]. Moreover, in mice fed HFDdiet enriched in polyphenols the upregulation of fatty acid and TG synthesis-related genes (FAS, SCD1) was reversed [117]. In diet-induced obese C57BL/mice a polyphenol-rich Rutgers Scarlet Lettuce improves glucose metabolism, liver lipid accumulation and reduced TNF-α [118]. In mice with fatty liver, induced by orally supplementation of
12
ACCEPTED MANUSCRIPT high-fat milk, a polyphenol-rich Chrysanthemum morifolium extract decreased lipid accumulation and hepatic PPARα gene expression [119]. In the light of this promising evidence, supplementation of polyphenols may represent a useful approach for the
T
management of patients with NAFLD, but additional research is required to confirm this
RI P
initial data.
SC
4.4.1 Anthocyanins
Anthocyanins (ACNs), a subclass of flavonoids, have been largely investigated for their
NU
potential protective effect in the prevention and treatment of different diseases. ACNs are the principal components of the red, blue and purple pigments of the majority of flower
MA
petals, fruits and vegetables such as blueberries, blackberries, raspberries, strawberries, blackcurrants, elderberries, grapes, cranberries, red cabbage, red radishes and spinach. ACNs in plants mainly exist in glycosidic forms, a total of more than 500 ACNs are
ED
known depending on the hydroxylation, methoxylation patterns on the B ring, and glycosylation with different sugar units [120]. The colour of ACNs is pH-dependent, i.e.,
PT
red in acidic and blue in basic conditions and they are chemically stable in acidic solutions [107]. To evaluate their beneficial effects on human health it must be
CE
considered that ACNs are rapidly metabolized and their presence in the circulation is limited to a few hours. Despite their low absorption and rapid metabolism, regular intake
AC
of ACNs may ameliorate hyperglycaemia, modulate endothelial function, and decrease inflammation [121]. Moreover, it has been investigated their role in the prevention of oxidative stress by scavenging reactive oxygen species and free radicals [122] and their role in the modulation of lipid metabolism and fat deposition [108, 123] in different tissues, including the liver. As we recently reviewed [121], ACNs can reduce hepatic lipid accumulation, but their impact on NAFLD has yet to be understood. Until now, only few clinical studies on humans are available and they diverge for ACNs source, doses and clinical features of patients. Suda et al. showed an effect of ACN intake (200 mg acylated ACNs from purple sweet potato) in the reduction of liver enzymes (e.g. gammaglutamyltransferases) in subjects with borderline levels of one or more hepatic markers [122]. In a recent study, NAFLD patients received either purified ACNs (320 mg/d) derived from bilberry and black currant or placebo for 12 weeks. Individuals receiving
13
ACCEPTED MANUSCRIPT ACNs showed a decrease in plasma alanine aminotransferase, cytokeratin-18 fragment and myeloperoxidase, and an overall improvement of insulin resistance [123]. Several in vitro studies, performed mainly in HepG2 cells supplemented with oleic acid
T
and/or palmitic acid, highlighted three different mechanisms of action by which ACNs
RI P
could prevent the progression of liver dysfunction/damage: inhibition of lipogenesis (i.e. reducing SREBP1c), promotion of lipolysis (i.e. inducing PPARα activity with activation
SC
of AMPK pathway) and reduction of oxidative stress (i.e. induction of antioxidant enzymes). Mulberry ACNs (0.1, 0.3, 0.5 mg/mL) supplementation in HepG2 reduced
NU
lipogenesis (SREBP-1, FAS, ACC and A-FABP), cholesterol biosynthesis (SREBP-2 and HMGCR) and TG biosynthesis, and enhanced fatty acid β-oxidation (PPARα and CPT-1) [124]. Cyanidin 3-O-glucoside reduced cellular lipid concentration in HepG2 cells by
MA
rewiring the expression of genes involved in lipid metabolic pathway as PPARα [125], whereas in primary mice hepatocytes it decreased intracellular ROS production acting as
ED
free radical scavenger and enhanced PI3K/Akt activation [126]. In vivo studies were performed in different experimental models of NAFLD and
PT
metabolic syndrome and evaluated different outcomes as lipid metabolism, oxidative stress, and liver damage. Obese mice supplemented with 200 mg/Kg per day of
CE
anthocyanin fraction extracted from purple sweet potato showed a reduced hepatic fat accumulation associated with a decreased hepatic lipogenesis [127]. Moro juice with an
AC
ACN content of 85 mg/L administered ad libitum to mice prevented fatty liver suppressing LXR-α expression and activity [128]. Moreover 1 g of purified ACN from bilberry and blackcurrant administered to mice ameliorated hepatic steatosis, inflammation, oxidative stress as well as fibrosis [129]. Anthocyanin-rich bilberry (Vaccinium myrtillus L.) extract was tested in E3Leiden (E3L) mice fed high-fat/highcholesterol diet. The anthocyanin extract reduced NASH development, attenuating both steatosis and inflammation and reduced hepatic fibrosis. These effects were associated with a decreased hepatic free cholesterol accumulation and cholesterol crystal formation. On the basis of these data, ACN-rich food could be useful for the prevention of liver diseases as NAFLD, even if additional studies are needed to deeply characterize the molecular mechanism of the different extracts.
14
ACCEPTED MANUSCRIPT 4.4.2 Silibinin Silymarin and its major costituent, Silibinin, are flavonoid compounds extracted from the medicinal plant Silybum marianum (milk thistle). Extracts have traditionally been used
T
for the treatments of liver disease [130-134].
RI P
Only few controlled randomized studies has been conducted in patients with NAFLD. These studies suggested that silymarin could reduce steatosis severity, liver ballooning
SC
and fibrosis, acting also as efficient insulin sensitizer and lowering aminotransferase levels in both short and long term trials [135]. In a study where patients received Vitamin
NU
E, L-gluthatione, L-cysteine, L-methionine and Silybum Marianum, it was observed that silymarin was effective in reducing the biochemical and ultrasonographic changes
MA
induced by NAFLD. These data were in agreement with those obtained by other authors [136]. Similarly, in a multicenter, double-blind clinical trial, patients with steatosis received silybinin combined with phosphatidylcholine and vitamin E for 12 months.
ED
Combined treatment was associated with an improvement in liver enzymes, insulin resistance and liver histology without increase in body weight [137]. In another recent
PT
study the intake of 210 mg/day silymarin orally for 8 weeks decreased hepatic enzymes in patients with NASH [138].
CE
Few in vitro study investigated silibinin properties. In hepatoma cells silibinin prevented lipid accumulation and resistin induction by fatty acids targeting the insulin signaling
AC
pathway [139]. In hepatic stellate cells isolated from human liver, silybin inhibited dosedependently cell proliferation, cell motility and de novo synthesis of extracellular matrix components. Silibinin was also confirmed to act as a potent anti-oxidant and antiinflammatory agent [140]. As concern in vivo studies, in obese db/db mice fed MCD silibinin decreased IR, serum ALT and NAFLD histological activity. This was associated with reduced oxidative stress and inflammation, due to lower isoprostanes, 8-OHG and TNF-α expression and restored mitochondrial reduced glutathion levels [141]. Again, in obese mice fed MCD, and in rats fed HFD, silibinin improved hepatic oxidative and nitrosative stress mediated by iNOS and inflammation modulating the expression and the activity of lipid metabolic enzymes [142]. This resulted in improvement in liver damage. In HFD rats, silibilin ameliorated IR
15
ACCEPTED MANUSCRIPT mainly by reducing visceral fat, up-regulating lipolysis and inhibiting gluconeogenesis [143]. These findings are a first step in the comprehension of the plausible mechanisms of
T
action of silibilinin, but further work is necessary to better characterize the possible use
RI P
of these polyphenolic compounds.
SC
4.4.3 Resveratrol
Resveratrol (trans-3,4’,5-trihydroxystilbene) is a stilbene occurring naturally in several
NU
plants and provided in the diet by various food stuffs such as grapes, berries, red wine and nuts. Evidences have shown its health benefits, such as improvement of insulin
MA
sensitivity and glucose tolerance, reduction of serum lipids and suppression of inflammation and oxidative stress. Moreover, resveratrol is able to modify lipid metabolism and more specifically to induce a reduction in liver TG content [144]. Few
ED
studies were performed in humans with conflicting results. Recently, patients with NAFLD who received 1500-mg resveratrol capsule twice daily for 12 weeks had and
PT
improvement of liver enzymes, insulin resistance and inflammation [145]. Similarly, patients receiving 50 mg resveratrol twice daily for three months associated with lifestyle
CE
modification had a higher attenuation of inflammatory markers and hepatocellular apoptosis compared to placebo treatment [144]. Conversely, 8 weeks administration of
AC
3000 mg resveratrol led to increased liver enzymes in NAFLD patients [146]. Few in vitro studies investigated the potential hepatoprotective effect of resveratrol. In primary rat hepatocytes, resveratrol supplementation (25 µmol/L) reduced ACC activity [147]. In a study performed in HepG2 cells exposed to high concentration of glucose, resveratrol supplementation reduced triacylglycerol accumulation by increasing AMPK activity and down-regulating SREBP-1c and ACC activity [148]. In vivo studies revealed that resveratrol could reduce liver weight and TG content. In mice treated with 22.4 mg resveratrol/kg, histological examination revealed a reduced accumulation of large lipid droplets [149]. Recent studies in mice fed high fat diet showed that resveratrol protected the liver from fat accumulation by activating Sirt1 [150, 151]. Sirt1, a NAD dependent deacetylase, stimulates the activity of FOXO1 [152], which may in turn indirectly inhibit SREBP1 expression [153, 154], suggesting that the
16
ACCEPTED MANUSCRIPT AMPK/Sirt1 axis could down-regulate genes of the lipogenic pathways (FAS, ACC) and up-regulate genes of the lypolitic pathway (PPARα, CPT-1). As concern the antioxidant activity, in Zucker rats supplemented with two different doses of resveratrol (15 and 45
T
mg/kg body weight, it was able to reduce oxidative damage in liver measured as hepatic
RI P
thiobarbituric acid and oxidized glutathione (GSSG) levels [153].
In conclusion, recent evidence demonstrated that resveratrol is effective in decreasing de
SC
novo lipogenesis in the liver and it could be used in the prevention of liver diseases.
NU
5. Minerals
It is generally recognised a progressive decay in the homeostasis of trace minerals in patients with NAFLD; this may reflects an increased oxidative stress and
MA
inflammation condition. In particular, minerals such as copper, selenium and iron have been investigated for their possible contribution to the development and treatment of liver
ED
diseases as NAFLD.
PT
5.1 Copper
Copper has a role in antioxidant defence, lipid peroxidation and mitochondrial function. deficiency
has
CE
Copper
been
linked
to
different
metabolic
disorders
as
hypercholesterolemia, increased blood pressure and glucose intolerance both in rodents
AC
[155, 156] and in humans [157]. Since inadequate copper availability may increase lipid accumulation in the liver it has been investigated its potential contribution to the development of NAFLD. Hepatic copper concentrations were reduced in NAFLD and inversely correlated with steatosis, NASH and IR [157]. Development of hepatic steatosis and IR in response to dietary copper restriction in rats suggests that copper availability has a causal role in the development of NAFLD [157]. Interestingly, fructose feeding exacerbates complications of copper deficiency. In rats, fructose consumption impaired copper status and precipitated copper deficiency possibly inhibiting its absorption through the intestinal epithelium. Moreover, copper deficiency and fructose appear to act together to accelerate hepatic fat accumulation and liver damage [156, 158]. According with histological findings, copper deficiency markedly suppressed CPT-1 and up-regulated FAS expression [158]. In addition, copper deficiency
17
ACCEPTED MANUSCRIPT also contributed to an impaired antioxidant defence system considering that the activity of Cu/Zn superoxide dismutase depends on adequate copper availability [159].
T
5.2 Selenium
RI P
Selenium deficiency could be considered a dietary condition correlated with oxidative stress in patients with liver diseases [160]. Selenium levels have been associated with
SC
cardiovascular disease and its supplementation leads to decrease in total cholesterol and triglyceride levels [161]. Unfortunately, selenium status on NAFLD has not been yet
NU
investigated.
Human hepatoblastoma cells supplemented with selenite showed a reduced TGFβ1-
MA
induced collagen and IL-8 production and maximized the expression of antioxidant enzymes in response to FFAs overload [162]. In experimental models selenium supplementation decreased triglyceride levels, protected LDL from oxidation by restoring
ED
the antioxidant properties of the low density lipoprotein (LDL) associated enzyme Paraoxonase 1 [163].
PT
Considering that, in vitro and in vivo selenium supplementation has shown a potential effect in the reduction of oxidative stress, it is important to take into account the possible
AC
5.3 Iron
CE
clinical implication in subjects with liver disease who have selenium deficiency.
Iron is essential to the life of all mammalian organisms. It has a key role in oxygen transport and in enzymes involved in mitochondrial respiration, DNA biosynthesis and the citric acid cycle via the capability to change its redox state. However, this characteristic also renders excess iron detrimental, mostly via the formation of reactive oxygen species, which may lead to severe organ damage. Iron perturbations are frequently observed in patients with obesity, insulin resistance and NAFLD. The term Dysmetabolic Iron Overload Syndrome (DIOS) is now most frequently used to describe the typical association of hepatic steatosis with mild to moderate iron deposition in liver biopsies and increased serum ferritin in patients with NAFLD [164]. Hyperferritinemia is usually associated with NASH and the severity of liver damage whereas iron depletion, achieved by phlebotomy, in patients with mild iron overload
18
ACCEPTED MANUSCRIPT could have beneficial effects more than lifestyle modifications alone in normalizing insulin resistance and liver enzymes [165, 166]. Moreover, iron depletion up-regulated glucose uptake and increased insulin receptor expression and signaling in hepatocytes in
T
vitro and in vivo [167], whereas dietary iron supplementation induced IR and
RI P
dyslipidemia [168]. To investigate the mechanisms underlying DIOS, we recently examined the effect of FFAs on hepatic iron metabolism. The main finding was that
SC
exposure of hepatocytes to FFAs, leading to steatosis, was associated with a subversion of iron metabolism characterized by increased expression of transferrin receptor, and
NU
facilitation of iron storage [169]. Additional studies are warranted to evaluate the
MA
potential of iron reductive therapy on clinical outcomes in NAFLD patients.
6. Conclusions
NAFLD, a disease caused by an unhealthy eating behaviour and lifestyle has become the
ED
leading cause of liver diseases in the Western countries. To date, there are no approved drugs for this indication and the main clinical recommendation as an initial step is
PT
lifestyle modification including both improvement of dietary pattern and increased physical activity. The identification of the molecular mechanisms leading to fat
CE
accumulation, oxidative balance impairment and liver fibrosis is expected to improve both diagnostic and therapeutic approaches. Food bioactive compounds, which modulate
AC
the activation of genes involved in lipogenesis, fibrogenesis, lipid peroxidation and inflammation represent a new attractive therapeutic approach for this condition.
19
ACCEPTED MANUSCRIPT Acknowledgements The authors would like to thank Dr Cristian Del Bo’ and the Metabolic Liver Diseases Research Lab for careful reading of the manuscript and suggestions. Luca Valenti and
T
Patrizia Riso designed the study and critically reviewed the paper literature and approved
RI P
the final manuscript. Paola Dongiovanni wrote the paper draft and contributed to critical discussion of results. Claudia Lanti performed the literature search and contributed to the
AC
CE
PT
ED
MA
NU
SC
writing of the paper draft. The authors declare no conflict of interest.
20
ACCEPTED MANUSCRIPT References [1] Angulo P. Nonalcoholic fatty liver disease. N Engl J Med. 2002;346:1221-31.
T
[2] Browning JD, Szczepaniak LS, Dobbins R, Nuremberg P, Horton JD, Cohen JC, et impact of ethnicity. Hepatology. 2004;40:1387-95.
RI P
al. Prevalence of hepatic steatosis in an urban population in the United States:
SC
[3] Blachier M, Leleu H, Peck-Radosavljevic M, Valla DC, Roudot-Thoraval F. The burden of liver disease in Europe: a review of available epidemiological data. J
NU
Hepatol.58:593-608.
[4] Marchesini G, Brizi M, Morselli-Labate AM, Bianchi G, Bugianesi E, McCullough
MA
AJ, et al. Association of nonalcoholic fatty liver disease with insulin resistance. Am J Med. 1999;107:450-5.
[5] Fabbrini E, Mohammed BS, Magkos F, Korenblat KM, Patterson BW, Klein S.
ED
Alterations in adipose tissue and hepatic lipid kinetics in obese men and women with nonalcoholic fatty liver disease. Gastroenterology. 2008;134:424-31.
PT
[6] Cohen JC, Horton JD, Hobbs HH. Human fatty liver disease: old questions and new insights. Science.332:1519-23.
CE
[7] Kleiner DE, Brunt EM, Van Natta M, Behling C, Contos MJ, Cummings OW, et al. Design and validation of a histological scoring system for nonalcoholic fatty liver
AC
disease. Hepatology. 2005;41:1313-21. [8] Day CP. From fat to inflammation. Gastroenterology. 2006;130:207-10. [9] Bugianesi E, Leone N, Vanni E, Marchesini G, Brunello F, Carucci P, et al. Expanding the natural history of nonalcoholic steatohepatitis: from cryptogenic cirrhosis to hepatocellular carcinoma. Gastroenterology. 2002;123:134-40. [10] Liu YL, Patman GL, Leathart JB, Piguet AC, Burt AD, Dufour JF, et al. Carriage of the PNPLA3 rs738409 C >G polymorphism confers an increased risk of nonalcoholic fatty liver disease associated hepatocellular carcinoma. J Hepatol.61:75-81. [11] Dongiovanni P, Anstee QM, Valenti L. Genetic predisposition in NAFLD and NASH: impact on severity of liver disease and response to treatment. Curr Pharm Des.19:5219-38.
21
ACCEPTED MANUSCRIPT [12] Eslamparast T, Eghtesad S, Poustchi H, Hekmatdoost A. Recent advances in dietary supplementation, in treating non-alcoholic fatty liver disease. World J Hepatol.7:204-12.
T
[13] Aguirre L, Portillo MP, Hijona E, Bujanda L. Effects of resveratrol and other
RI P
polyphenols in hepatic steatosis. World J Gastroenterol.20:7366-80. [14] Yamaguchi K, Yang L, McCall S, Huang J, Yu XX, Pandey SK, et al. Inhibiting
SC
triglyceride synthesis improves hepatic steatosis but exacerbates liver damage and fibrosis in obese mice with nonalcoholic steatohepatitis. Hepatology. 2007;45:1366-
NU
74.
[15] Marchesini G, Brizi M, Bianchi G, Tomassetti S, Bugianesi E, Lenzi M, et al.
MA
Nonalcoholic fatty liver disease: a feature of the metabolic syndrome. Diabetes. 2001;50:1844-50.
[16] Day CP. Steatohepatitis: a tale of two "hits"? Gastroenterology. 1998;114:842-5.
ED
[17] Tilg H, Moschen AR. Evolution of inflammation in nonalcoholic fatty liver disease: the multiple parallel hits hypothesis. Hepatology.52:1836-46.
PT
[18] Valenti L, Ludovica Fracanzani A, Fargion S. The immunopathogenesis of alcoholic and nonalcoholic steatohepatitis: two triggers for one disease? Semin
CE
Immunopathol. 2009.
[19] Miele L, Valenza V, La Torre G, Montalto M, Cammarota G, Ricci R, et al.
AC
Increased intestinal permeability and tight junction alterations in nonalcoholic fatty liver disease. Hepatology. 2009. [20] Anstee QM, Daly AK, Day CP. Genetics of alcoholic and nonalcoholic fatty liver disease. Semin Liver Dis.31:128-46. [21] Promrat K, Kleiner DE, Niemeier HM, Jackvony E, Kearns M, Wands JR, et al. Randomized controlled trial testing the effects of weight loss on nonalcoholic steatohepatitis. Hepatology.51:121-9. [22] Sullivan S, Kirk EP, Mittendorfer B, Patterson BW, Klein S. Randomized trial of exercise effect on intrahepatic triglyceride content and lipid kinetics in nonalcoholic fatty liver disease. Hepatology.55:1738-45.
22
ACCEPTED MANUSCRIPT [23] Harrison SA, Fecht W, Brunt EM, Neuschwander-Tetri BA. Orlistat for overweight subjects with nonalcoholic steatohepatitis: A randomized, prospective trial. Hepatology. 2009;49:80-6.
T
[24] Centis E, Moscatiello S, Bugianesi E, Bellentani S, Fracanzani AL, Calugi S, et al.
RI P
Stage of change and motivation to healthier lifestyle in non-alcoholic fatty liver disease. J Hepatol.58:771-7.
SC
[25] St George A, Bauman A, Johnston A, Farrell G, Chey T, George J. Independent effects of physical activity in patients with nonalcoholic fatty liver disease.
NU
Hepatology. 2009;50:68-76.
[26] Perseghin G, Lattuada G, De Cobelli F, Ragogna F, Ntali G, Esposito A, et al. Diabetes Care. 2007;30:683-8.
MA
Habitual physical activity is associated with intrahepatic fat content in humans. [27] Johnson NA, Sachinwalla T, Walton DW, Smith K, Armstrong A, Thompson MW,
ED
et al. Aerobic exercise training reduces hepatic and visceral lipids in obese individuals without weight loss. Hepatology. 2009;50:1105-12.
PT
[28] Sreenivasa Baba C, Alexander G, Kalyani B, Pandey R, Rastogi S, Pandey A, et al. Effect of exercise and dietary modification on serum aminotransferase levels in
CE
patients with nonalcoholic steatohepatitis. J Gastroenterol Hepatol. 2006;21:191-8. [29] Hallsworth K, Fattakhova G, Hollingsworth KG, Thoma C, Moore S, Taylor R, et
AC
al. Resistance exercise reduces liver fat and its mediators in non-alcoholic fatty liver disease independent of weight loss. Gut.60:1278-83. [30] Ryan MC, Desmond P, Wilson A. Reply to: "might some of the beneficial effects of the Mediterranean diet on non-alcoholic fatty liver disease be mediated by reduced iron stores?". J Hepatol.59:640. [31] Musso G, Gambino R, De Michieli F, Cassader M, Rizzetto M, Durazzo M, et al. Dietary habits and their relations to insulin resistance and postprandial lipemia in nonalcoholic steatohepatitis. Hepatology. 2003;37:909-16. [32] Ferder L, Ferder MD, Inserra F. The role of high-fructose corn syrup in metabolic syndrome and hypertension. Curr Hypertens Rep.12:105-12. [33] Chiu S, Sievenpiper JL, de Souza RJ, Cozma AI, Mirrahimi A, Carleton AJ, et al. Effect of fructose on markers of non-alcoholic fatty liver disease (NAFLD): a 23
ACCEPTED MANUSCRIPT systematic review and meta-analysis of controlled feeding trials. Eur J Clin Nutr.68:416-23. [34] Vos MB, Lavine JE. Dietary fructose in nonalcoholic fatty liver disease.
T
Hepatology.57:2525-31.
RI P
[35] Ma J, Fox CS, Jacques PF, Speliotes EK, Hoffmann U, Smith CE, et al. Sugarsweetened beverage, diet soda, and fatty liver disease in the Framingham Heart
SC
Study cohorts. J Hepatol.
[36] Bergheim I, Weber S, Vos M, Kramer S, Volynets V, Kaserouni S, et al. Antibiotics endotoxin. J Hepatol. 2008;48:983-92.
NU
protect against fructose-induced hepatic lipid accumulation in mice: role of
MA
[37] Toshimitsu K, Matsuura B, Ohkubo I, Niiya T, Furukawa S, Hiasa Y, et al. Dietary habits and nutrient intake in non-alcoholic steatohepatitis. Nutrition. 2007;23:4652.
ED
[38] Lomonaco R, Sunny NE, Bril F, Cusi K. Nonalcoholic fatty liver disease: current issues and novel treatment approaches. Drugs.73:1-14.
PT
[39] Musso G, Gambino R, Cassader M, Pagano G. A meta-analysis of randomized trials for the treatment of nonalcoholic fatty liver disease. Hepatology.52:79-104.
CE
[40] Duseja A, Das A, Dhiman RK, Chawla YK, Thumburu KT, Bhadada S, et al. Metformin is effective in achieving biochemical response in patients with
AC
nonalcoholic fatty liver disease (NAFLD) not responding to lifestyle interventions. Ann Hepatol. 2007;6:222-6. [41] Rakoski MO, Singal AG, Rogers MA, Conjeevaram H. Meta-analysis: insulin sensitizers for the treatment of non-alcoholic steatohepatitis. Aliment Pharmacol Ther.32:1211-21. [42] Zhu FS, Liu S, Chen XM, Huang ZG, Zhang DW. Effects of n-3 polyunsaturated fatty acids from seal oils on nonalcoholic fatty liver disease associated with hyperlipidemia. World J Gastroenterol. 2008;14:6395-400. [43] Masterton GS, Plevris JN, Hayes PC. Review article: omega-3 fatty acids - a promising novel therapy for non-alcoholic fatty liver disease. Aliment Pharmacol Ther.31:679-92.
24
ACCEPTED MANUSCRIPT [44] Capanni M, Calella F, Biagini MR, Genise S, Raimondi L, Bedogni G, et al. Prolonged n-3 polyunsaturated fatty acid supplementation ameliorates hepatic steatosis in patients with non-alcoholic fatty liver disease: a pilot study. Aliment
T
Pharmacol Ther. 2006;23:1143-51.
RI P
[45] Spadaro L, Magliocco O, Spampinato D, Piro S, Oliveri C, Alagona C, et al. Effects of n-3 polyunsaturated fatty acids in subjects with nonalcoholic fatty liver disease.
SC
Dig Liver Dis. 2008;40:194-9.
[46] Tanaka N, Sano K, Horiuchi A, Tanaka E, Kiyosawa K, Aoyama T. Highly purified
NU
eicosapentaenoic acid treatment improves nonalcoholic steatohepatitis. J Clin Gastroenterol. 2008;42:413-8.
MA
[47] Scorletti E, Bhatia L, McCormick KG, Clough GF, Nash K, Calder PC, et al. Design and rationale of the WELCOME trial: A randomised, placebo controlled study to test the efficacy of purified long chainomega-3 fatty acid treatment in non-alcoholic fatty
ED
liver disease [corrected]. Contemp Clin Trials.37:301-11. [48] Nobili V, Bedogni G, Alisi A, Pietrobattista A, Rise P, Galli C, et al.
PT
Docosahexaenoic acid supplementation decreases liver fat content in children with non-alcoholic fatty liver disease: double-blind randomised controlled clinical trial.
CE
Arch Dis Child.96:350-3.
[49] Nobili V, Alisi A, Della Corte C, Rise P, Galli C, Agostoni C, et al. Docosahexaenoic
AC
acid for the treatment of fatty liver: randomised controlled trial in children. Nutr Metab Cardiovasc Dis.23:1066-70. [50] Parker HM, Johnson NA, Burdon CA, Cohn JS, O'Connor HT, George J. Omega-3 supplementation and non-alcoholic fatty liver disease: a systematic review and meta-analysis. J Hepatol.56:944-51. [51] Argo CK, Patrie JT, Lackner C, Henry TD, de Lange EE, Weltman AL, et al. Effects of n-3 fish oil on metabolic and histological parameters in NASH: a double-blind, randomized, placebo-controlled trial. J Hepatol.62:190-7. [52] Oh DY, Talukdar S, Bae EJ, Imamura T, Morinaga H, Fan W, et al. GPR120 is an omega-3 fatty acid receptor mediating potent anti-inflammatory and insulinsensitizing effects. Cell.142:687-98.
25
ACCEPTED MANUSCRIPT [53] Nobili V, Carpino G, Alisi A, De Vito R, Franchitto A, Alpini G, et al. Role of docosahexaenoic acid treatment in improving liver histology in pediatric nonalcoholic fatty liver disease. PLoS One.9:e88005.
RI P
steatohepatitis. J Pediatr Gastroenterol Nutr.59:423-4.
T
[54] Valenti L, Nobili V. Deciphering the role of omega3 fatty acids in nonalcoholic [55] Nagao K, Nakamitsu K, Ishida H, Yoshinaga K, Nagai T, Mizobe H, et al. fatty acids in HepG2 cells. J Oleo Sci.63:979-85.
SC
Comparison of the lipid-lowering effects of four different n-3 highly unsaturated
NU
[56] Di Nunzio M, Valli V, Bordoni A. Pro- and anti-oxidant effects of polyunsaturated fatty acid supplementation in HepG2 cells. Prostaglandins Leukot
MA
Essent Fatty Acids.85:121-7.
[57] Shiba S, Tsunoda N, Wakutsu M, Muraki E, Sonoda M, Tam PS, et al. Regulation of lipid metabolism by palmitoleate and eicosapentaenoic acid (EPA) in mice fed a
ED
high-fat diet. Biosci Biotechnol Biochem.75:2401-3. [58] Matsumoto T, Terai S, Oishi T, Kuwashiro S, Fujisawa K, Yamamoto N, et al.
PT
Medaka as a model for human nonalcoholic steatohepatitis. Dis Model Mech.3:43140.
CE
[59] Kajikawa S, Imada K, Takeuchi T, Shimizu Y, Kawashima A, Harada T, et al. Eicosapentaenoic acid attenuates progression of hepatic fibrosis with inhibition of
AC
reactive oxygen species production in rats fed methionine- and choline-deficient diet. Dig Dis Sci.56:1065-74. [60] Kajikawa S, Harada T, Kawashima A, Imada K, Mizuguchi K. Highly purified eicosapentaenoic acid ethyl ester prevents development of steatosis and hepatic fibrosis in rats. Dig Dis Sci.55:631-41. [61] Poudyal H, Panchal SK, Ward LC, Brown L. Effects of ALA, EPA and DHA in highcarbohydrate, high-fat diet-induced metabolic syndrome in rats. J Nutr Biochem.24:1041-52. [62] Tang X, Li ZJ, Xu J, Xue Y, Li JZ, Wang JF, et al. Short term effects of different omega-3 fatty acid formulation on lipid metabolism in mice fed high or low fat diet. Lipids Health Dis.11:70.
26
ACCEPTED MANUSCRIPT [63] Lengqvist J, Mata De Urquiza A, Bergman AC, Willson TM, Sjovall J, Perlmann T, et al. Polyunsaturated fatty acids including docosahexaenoic and arachidonic acid bind to the retinoid X receptor alpha ligand-binding domain. Mol Cell Proteomics.
T
2004;3:692-703.
RI P
[64] Vemuri M, Kelley DS, Mackey BE, Rasooly R, Bartolini G. Docosahexaenoic Acid (DHA) But Not Eicosapentaenoic Acid (EPA) Prevents Trans-10, Cis-12 Conjugated
SC
Linoleic Acid (CLA)-Induced Insulin Resistance in Mice. Metab Syndr Relat Disord. 2007;5:315-22.
NU
[65] Birringer M, Pfluger P, Kluth D, Landes N, Brigelius-Flohe R. Identities and differences in the metabolism of tocotrienols and tocopherols in HepG2 cells. J Nutr.
MA
2002;132:3113-8.
[66] Takitani K, Miyazaki H, Yoden A, Tamai H. Children's toxicology from bench to bed--Liver Injury (2): Mechanism of antioxidant therapy for nonalcoholic fatty liver
ED
disease. J Toxicol Sci. 2009;34 Suppl 2:SP223-8. [67] Miyazaki H, Takitani K, Koh M, Yoden A, Tamai H. The alpha-tocopherol status
PT
and expression of alpha-tocopherol-related proteins in methionine-choline deficient rats treated with vitamin E. J Clin Biochem Nutr.54:190-7.
CE
[68] Sanyal AJ, Campbell-Sargent C, Mirshahi F, Rizzo WB, Contos MJ, Sterling RK, et al. Nonalcoholic steatohepatitis: association of insulin resistance and mitochondrial
AC
abnormalities. Gastroenterology. 2001;120:1183-92. [69] Seki S, Kitada T, Yamada T, Sakaguchi H, Nakatani K, Wakasa K. In situ detection of lipid peroxidation and oxidative DNA damage in non-alcoholic fatty liver diseases. J Hepatol. 2002;37:56-62. [70] MacDonald GA, Bridle KR, Ward PJ, Walker NI, Houglum K, George DK, et al. Lipid peroxidation in hepatic steatosis in humans is associated with hepatic fibrosis and occurs predominately in acinar zone 3. J Gastroenterol Hepatol. 2001;16:599606. [71] Sanyal AJ, Chalasani N, Kowdley KV, McCullough A, Diehl AM, Bass NM, et al. Pioglitazone, vitamin E, or placebo for nonalcoholic steatohepatitis. N Engl J Med.362:1675-85.
27
ACCEPTED MANUSCRIPT [72] Foster T, Budoff MJ, Saab S, Ahmadi N, Gordon C, Guerci AD. Atorvastatin and antioxidants for the treatment of nonalcoholic fatty liver disease: the St Francis Heart Study randomized clinical trial. Am J Gastroenterol.106:71-7.
T
[73] Thuma PE, Mabeza GF, Biemba G, Bhat GJ, McLaren CE, Moyo VM, et al. Effect of
RI P
iron chelation therapy on mortality in Zambian children with cerebral malaria. Trans R Soc Trop Med Hyg. 1998;92:214-8.
SC
[74] Nobili V, Manco M, Devito R, Ciampalini P, Piemonte F, Marcellini M. Effect of vitamin E on aminotransferase levels and insulin resistance in children with non-
NU
alcoholic fatty liver disease. Aliment Pharmacol Ther. 2006;24:1553-61. [75] Lavine JE, Schwimmer JB, Van Natta ML, Molleston JP, Murray KF, Rosenthal P,
MA
et al. Effect of vitamin E or metformin for treatment of nonalcoholic fatty liver disease in children and adolescents: the TONIC randomized controlled trial. JAMA.305:1659-68.
ED
[76] Albanes D, Till C, Klein EA, Goodman PJ, Mondul AM, Weinstein SJ, et al. Plasma tocopherols and risk of prostate cancer in the Selenium and Vitamin E Cancer
PT
Prevention Trial (SELECT). Cancer Prev Res (Phila).7:886-95. [77] Miller ER, 3rd, Pastor-Barriuso R, Dalal D, Riemersma RA, Appel LJ, Guallar E.
CE
Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Ann Intern Med. 2005;142:37-46.
AC
[78] Houglum K, Brenner DA, Chojkier M. d-alpha-tocopherol inhibits collagen alpha 1(I) gene expression in cultured human fibroblasts. Modulation of constitutive collagen gene expression by lipid peroxidation. J Clin Invest. 1991;87:2230-5. [79] Nieto N, Friedman SL, Greenwel P, Cederbaum AI. CYP2E1-mediated oxidative stress induces collagen type I expression in rat hepatic stellate cells. Hepatology. 1999;30:987-96. [80] Zaiden N, Yap WN, Ong S, Xu CH, Teo VH, Chang CP, et al. Gamma delta tocotrienols reduce hepatic triglyceride synthesis and VLDL secretion. J Atheroscler Thromb.17:1019-32. [81] Podszun MC, Grebenstein N, Spruss A, Schlueter T, Kremoser C, Bergheim I, et al. Dietary alpha-tocopherol and atorvastatin reduce high-fat-induced lipid
28
ACCEPTED MANUSCRIPT accumulation and down-regulate CD36 protein in the liver of guinea pigs. J Nutr Biochem.25:573-9. [82] Raso GM, Esposito E, Iacono A, Pacilio M, Cuzzocrea S, Canani RB, et al.
T
Comparative therapeutic effects of metformin and vitamin E in a model of non-
RI P
alcoholic steatohepatitis in the young rat. Eur J Pharmacol. 2009;604:125-31. [83] Chung MY, Yeung SF, Park HJ, Volek JS, Bruno RS. Dietary alpha- and gamma-
SC
tocopherol supplementation attenuates lipopolysaccharide-induced oxidative stress and inflammatory-related responses in an obese mouse model of nonalcoholic
NU
steatohepatitis. J Nutr Biochem.21:1200-6.
[84] Tzanetakou IP, Doulamis IP, Korou LM, Agrogiannis G, Vlachos IS, Pantopoulou
MA
A, et al. Water Soluble Vitamin E Administration in Wistar Rats with Non-alcoholic Fatty Liver Disease. Open Cardiovasc Med J.6:88-97. [85] Phung N, Pera N, Farrell G, Leclercq I, Hou JY, George J. Pro-oxidant-mediated
ED
hepatic fibrosis and effects of antioxidant intervention in murine dietary steatohepatitis. Int J Mol Med. 2009;24:171-80.
PT
[86] Alvarez JA, Ashraf A. Role of vitamin d in insulin secretion and insulin sensitivity for glucose homeostasis. Int J Endocrinol.2010:351385.
CE
[87] Zuniga S, Firrincieli D, Housset C, Chignard N. Vitamin D and the vitamin D receptor in liver pathophysiology. Clin Res Hepatol Gastroenterol.35:295-302.
AC
[88] Smith HJ, Meremikwu M. Iron chelating agents for treating malaria. Cochrane Database Syst Rev. 2000:CD001474. [89] Smotkin-Tangorra M, Purushothaman R, Gupta A, Nejati G, Anhalt H, Ten S. Prevalence of vitamin D insufficiency in obese children and adolescents. J Pediatr Endocrinol Metab. 2007;20:817-23. [90] Bradlee ML, Singer MR, Qureshi MM, Moore LL. Food group intake and central obesity among children and adolescents in the Third National Health and Nutrition Examination Survey (NHANES III). Public Health Nutr.13:797-805. [91] Kwok RM, Torres DM, Harrison SA. Vitamin D and nonalcoholic fatty liver disease (NAFLD): is it more than just an association? Hepatology.58:1166-74.
29
ACCEPTED MANUSCRIPT [92] Kasapoglu B, Turkay C, Yalcin KS, Carlioglu A, Sozen M, Koktener A. Low vitamin D levels are associated with increased risk for fatty liver disease among non-obese adults. Clin Med.13:576-9.
T
[93] Targher G, Bertolini L, Scala L, Cigolini M, Zenari L, Falezza G, et al. Associations
RI P
between serum 25-hydroxyvitamin D3 concentrations and liver histology in patients with non-alcoholic fatty liver disease. Nutr Metab Cardiovasc Dis.
SC
2007;17:517-24.
[94] Kitson MT, Roberts SK. D-livering the message: the importance of vitamin D
NU
status in chronic liver disease. J Hepatol.57:897-909.
[95] Barchetta I, Carotti S, Labbadia G, Gentilucci UV, Muda AO, Angelico F, et al.
MA
Liver vitamin D receptor, CYP2R1, and CYP27A1 expression: relationship with liver histology and vitamin D3 levels in patients with nonalcoholic steatohepatitis or hepatitis C virus. Hepatology.56:2180-7.
ED
[96] Foroughi M, Maghsoudi Z, Ghiasvand R, Iraj B, Askari G. Effect of Vitamin D J Prev Med.5:969-75.
PT
Supplementation on C-reactive Protein in Patients with Nonalcoholic Fatty Liver. Int [97] Sharifi N, Amani R, Hajiani E, Cheraghian B. Does vitamin D improve liver
CE
enzymes, oxidative stress, and inflammatory biomarkers in adults with nonalcoholic fatty liver disease? A randomized clinical trial. Endocrine.47:70-80.
AC
[98] Nishida S, Ozeki J, Makishima M. Modulation of bile acid metabolism by 1alphahydroxyvitamin D3 administration in mice. Drug Metab Dispos. 2009;37:2037-44. [99] Theodoropoulos C, Demers C, Petit JL, Gascon-Barre M. High sensitivity of rat hepatic vitamin D3-25 hydroxylase CYP27A to 1,25-dihydroxyvitamin D3 administration. Am J Physiol Endocrinol Metab. 2003;284:E138-47. [100] Sakuma T, Miyamoto T, Jiang W, Kakizawa T, Nishio SI, Suzuki S, et al. Inhibition of peroxisome proliferator-activated receptor alpha signaling by vitamin D receptor. Biochem Biophys Res Commun. 2003;312:513-9. [101] Chen Z, Gao C, Hua Y, Keep RF, Muraszko K, Xi G. Role of iron in brain injury after intraventricular hemorrhage. Stroke. 2011;42:465-70. [102] Ding N, Yu RT, Subramaniam N, Sherman MH, Wilson C, Rao R, et al. A vitamin D receptor/SMAD genomic circuit gates hepatic fibrotic response. Cell.153:601-13. 30
ACCEPTED MANUSCRIPT [103] Kong M, Zhu L, Bai L, Zhang X, Chen Y, Liu S, et al. Vitamin D deficiency promotes nonalcoholic steatohepatitis through impaired enterohepatic circulation in animal model. Am J Physiol Gastrointest Liver Physiol.307:G883-93.
T
[104] Roth CL, Elfers CT, Figlewicz DP, Melhorn SJ, Morton GJ, Hoofnagle A, et al.
RI P
Vitamin D deficiency in obese rats exacerbates nonalcoholic fatty liver disease and increases hepatic resistin and Toll-like receptor activation. Hepatology.55:1103-11.
SC
[105] Yin Y, Yu Z, Xia M, Luo X, Lu X, Ling W. Vitamin D attenuates high fat dietinduced hepatic steatosis in rats by modulating lipid metabolism. Eur J Clin
NU
Invest.42:1189-96.
[106] Del Rio D, Rodriguez-Mateos A, Spencer JP, Tognolini M, Borges G, Crozier A.
MA
Dietary (poly)phenolics in human health: structures, bioavailability, and evidence of protective effects against chronic diseases. Antioxid Redox Signal.18:1818-92. [107] Tsao R. Chemistry and biochemistry of dietary polyphenols. Nutrients.2:1231-
ED
46.
[108] Guo H, Zhong R, Liu Y, Jiang X, Tang X, Li Z, et al. Effects of bayberry juice on
PT
inflammatory and apoptotic markers in young adults with features of non-alcoholic fatty liver disease. Nutrition.30:198-203.
CE
[109] Chang HC, Peng CH, Yeh DM, Kao ES, Wang CJ. Hibiscus sabdariffa extract inhibits obesity and fat accumulation, and improves liver steatosis in humans. Food
AC
Funct.5:734-9.
[110] Van De Wier B, Koek GH, Bast A, Haenen GR. The Potential of Flavonoids in the Treatment of Non-alcoholic Fatty Liver Disease. Crit Rev Food Sci Nutr.0. [111] Nakagawa S, Kojima Y, Sekino K, Yamato S. Effect of polyphenols on 3hydroxy-3-methylglutaryl-coenzyme A lyase activity in human hepatoma HepG2 cell extracts. Biol Pharm Bull.36:1902-6. [112] Liu Y, Wang D, Zhang D, Lv Y, Wei Y, Wu W, et al. Inhibitory effect of blueberry polyphenolic compounds on oleic acid-induced hepatic steatosis in vitro. J Agric Food Chem.59:12254-63. [113] Vidyashankar S, Sandeep Varma R, Patki PS. Quercetin ameliorate insulin resistance and up-regulates cellular antioxidants during oleic acid induced hepatic steatosis in HepG2 cells. Toxicol In Vitro.27:945-53. 31
ACCEPTED MANUSCRIPT [114] Priore P, Caruso D, Siculella L, Gnoni GV. Rapid down-regulation of hepatic lipid metabolism by phenolic fraction from extra virgin olive oil. Eur J Nutr. [115] Liao CC, Ou TT, Huang HP, Wang CJ. The inhibition of oleic acid induced
RI P
of AMP-activated kinase. J Sci Food Agric.94:1154-62.
T
hepatic lipogenesis and the promotion of lipolysis by caffeic acid via up-regulation [116] Tsuruta Y, Nagao K, Kai S, Tsuge K, Yoshimura T, Koganemaru K, et al.
SC
Polyphenolic extract of lotus root (edible rhizome of Nelumbo nucifera) alleviates hepatic steatosis in obese diabetic db/db mice. Lipids Health Dis.10:202.
NU
[117] Park HJ, Jung UJ, Lee MK, Cho SJ, Jung HK, Hong JH, et al. Modulation of lipid metabolism by polyphenol-rich grape skin extract improves liver steatosis and
MA
adiposity in high fat fed mice. Mol Nutr Food Res.57:360-4. [118] Cheng DM, Pogrebnyak N, Kuhn P, Poulev A, Waterman C, Rojas-Silva P, et al. Polyphenol-rich Rutgers Scarlet Lettuce improves glucose metabolism and liver
ED
lipid accumulation in diet-induced obese C57BL/6 mice. Nutrition.30:S52-8. [119] Cui Y, Wang X, Xue J, Liu J, Xie M. Chrysanthemum morifolium extract
PT
attenuates high-fat milk-induced fatty liver through peroxisome proliferatoractivated receptor alpha-mediated mechanism in mice. Nutr Res.34:268-75.
CE
[120] Fang J. Bioavailability of anthocyanins. Drug Metab Rev.46:508-20. [121] Valenti L, Riso P, Mazzocchi A, Porrini M, Fargion S, Agostoni C. Dietary
AC
anthocyanins as nutritional therapy for nonalcoholic fatty liver disease. Oxid Med Cell Longev.2013:145421. [122] Suda I, Ishikawa F, Hatakeyama M, Miyawaki M, Kudo T, Hirano K, et al. Intake of purple sweet potato beverage affects on serum hepatic biomarker levels of healthy adult men with borderline hepatitis. Eur J Clin Nutr. 2008;62:60-7. [123] Zhang PW, Chen FX, Li D, Ling WH, Guo HH. A CONSORT-Compliant, Randomized, Double-Blind, Placebo-Controlled Pilot Trial of Purified Anthocyanin in Patients With Nonalcoholic Fatty Liver Disease. Medicine (Baltimore).94:e758. [124] Chang JJ, Hsu MJ, Huang HP, Chung DJ, Chang YC, Wang CJ. Mulberry anthocyanins inhibit oleic acid induced lipid accumulation by reduction of lipogenesis and promotion of hepatic lipid clearance. J Agric Food Chem.61:6069-76.
32
ACCEPTED MANUSCRIPT [125] Jia Y, Kim JY, Jun HJ, Kim SJ, Lee JH, Hoang MH, et al. Cyanidin is an agonistic ligand for peroxisome proliferator-activated receptor-alpha reducing hepatic lipid. Biochim Biophys Acta.1831:698-708.
T
[126] Jiang X, Tang X, Zhang P, Liu G, Guo H. Cyanidin-3-O-beta-glucoside protects
RI P
primary mouse hepatocytes against high glucose-induced apoptosis by modulating mitochondrial dysfunction and the PI3K/Akt pathway. Biochem Pharmacol.90:135-
SC
44.
[127] Hwang YP, Choi JH, Han EH, Kim HG, Wee JH, Jung KO, et al. Purple sweet
NU
potato anthocyanins attenuate hepatic lipid accumulation through activating adenosine monophosphate-activated protein kinase in human HepG2 cells and
MA
obese mice. Nutr Res.31:896-906.
[128] Salamone F, Li Volti G, Titta L, Puzzo L, Barbagallo I, La Delia F, et al. Moro orange juice prevents fatty liver in mice. World J Gastroenterol.18:3862-8.
ED
[129] Tang X, Shen T, Jiang X, Xia M, Sun X, Guo H, et al. Purified anthocyanins from bilberry and black currant attenuate hepatic mitochondrial dysfunction and Chem.63:552-61.
PT
steatohepatitis in mice with methionine and choline deficiency. J Agric Food
CE
[130] Cheung CW, Gibbons N, Johnson DW, Nicol DL. Silibinin--a promising new treatment for cancer. Anticancer Agents Med Chem.10:186-95.
AC
[131] Huseini HF, Larijani B, Heshmat R, Fakhrzadeh H, Radjabipour B, Toliat T, et al. The efficacy of Silybum marianum (L.) Gaertn. (silymarin) in the treatment of type II diabetes: a randomized, double-blind, placebo-controlled, clinical trial. Phytother Res. 2006;20:1036-9. [132] Al-Anati L, Essid E, Reinehr R, Petzinger E. Silibinin protects OTA-mediated TNF-alpha release from perfused rat livers and isolated rat Kupffer cells. Mol Nutr Food Res. 2009;53:460-6. [133] Jayaraj R, Deb U, Bhaskar AS, Prasad GB, Rao PV. Hepatoprotective efficacy of certain flavonoids against microcystin induced toxicity in mice. Environ Toxicol. 2007;22:472-9.
33
ACCEPTED MANUSCRIPT [134] Esser-Nobis K, Romero-Brey I, Ganten TM, Gouttenoire J, Harak C, Klein R, et al. Analysis of hepatitis C virus resistance to silibinin in vitro and in vivo points to a novel mechanism involving nonstructural protein 4B. Hepatology.57:953-63.
T
[135] Milosevic N, Milanovic M, Abenavoli L, Milic N. Phytotherapy and NAFLD--
RI P
from goals and challenges to clinical practice. Rev Recent Clin Trials.9:195-203. [136] Flora K, Hahn M, Rosen H, Benner K. Milk thistle (Silybum marianum) for the
SC
therapy of liver disease. Am J Gastroenterol. 1998;93:139-43.
[137] Loguercio C, Andreone P, Brisc C, Brisc MC, Bugianesi E, Chiaramonte M, et al.
NU
Silybin combined with phosphatidylcholine and vitamin E in patients with nonalcoholic fatty liver disease: a randomized controlled trial. Free Radic Biol
MA
Med.52:1658-65.
[138] Solhi H, Ghahremani R, Kazemifar AM, Hoseini Yazdi Z. Silymarin in treatment of non-alcoholic steatohepatitis: A randomized clinical trial. Caspian J Intern
ED
Med.5:9-12.
[139] Zhang Y, Hai J, Cao M, Pei S, Wang J, Zhang Q. Silibinin ameliorates steatosis
PT
and insulin resistance during non-alcoholic fatty liver disease development partly through targeting IRS-1/PI3K/Akt pathway. Int Immunopharmacol.17:714-20.
CE
[140] Trappoliere M, Caligiuri A, Schmid M, Bertolani C, Failli P, Vizzutti F, et al. Silybin, a component of sylimarin, exerts anti-inflammatory and anti-fibrogenic
AC
effects on human hepatic stellate cells. J Hepatol. 2009;50:1102-11. [141] Salamone F, Galvano F, Marino Gammazza A, Paternostro C, Tibullo D, Bucchieri F, et al. Silibinin improves hepatic and myocardial injury in mice with nonalcoholic steatohepatitis. Dig Liver Dis.44:334-42. [142] Salamone F, Galvano F, Cappello F, Mangiameli A, Barbagallo I, Li Volti G. Silibinin modulates lipid homeostasis and inhibits nuclear factor kappa B activation in experimental nonalcoholic steatohepatitis. Transl Res.159:477-86. [143] Yao J, Zhi M, Gao X, Hu P, Li C, Yang X. Effect and the probable mechanisms of silibinin in regulating insulin resistance in the liver of rats with non-alcoholic fatty liver. Braz J Med Biol Res.46:270-7.
34
ACCEPTED MANUSCRIPT [144] Faghihzadeh F, Adibi P, Rafiei R, Hekmatdoost A. Resveratrol supplementation improves inflammatory biomarkers in patients with nonalcoholic fatty liver disease. Nutr Res.34:837-43.
T
[145] Chen S, Zhao X, Ran L, Wan J, Wang X, Qin Y, et al. Resveratrol improves insulin
RI P
resistance, glucose and lipid metabolism in patients with non-alcoholic fatty liver disease: a randomized controlled trial. Dig Liver Dis.47:226-32.
SC
[146] Chachay VS, Macdonald GA, Martin JH, Whitehead JP, O'Moore-Sullivan TM, Lee P, et al. Resveratrol does not benefit patients with nonalcoholic fatty liver
NU
disease. Clin Gastroenterol Hepatol.12:2092-103 e1-6.
[147] Gnoni GV, Paglialonga G. Resveratrol inhibits fatty acid and triacylglycerol
MA
synthesis in rat hepatocytes. Eur J Clin Invest. 2009;39:211-8. [148] Shang J, Chen LL, Xiao FX, Sun H, Ding HC, Xiao H. Resveratrol improves nonalcoholic fatty liver disease by activating AMP-activated protein kinase. Acta
ED
Pharmacol Sin. 2008;29:698-706.
[149] Baur JA, Pearson KJ, Price NL, Jamieson HA, Lerin C, Kalra A, et al. Resveratrol
PT
improves health and survival of mice on a high-calorie diet. Nature. 2006;444:33742.
CE
[150] Deng XQ, Chen LL, Li NX. The expression of SIRT1 in nonalcoholic fatty liver disease induced by high-fat diet in rats. Liver Int. 2007;27:708-15.
AC
[151] Pfluger PT, Herranz D, Velasco-Miguel S, Serrano M, Tschop MH. Sirt1 protects against high-fat diet-induced metabolic damage. Proc Natl Acad Sci U S A. 2008;105:9793-8.
[152] Frescas D, Valenti L, Accili D. Nuclear trapping of the forkhead transcription factor FoxO1 via Sirt-dependent deacetylation promotes expression of glucogenetic genes. J Biol Chem. 2005;280:20589-95. [153] Zang M, Xu S, Maitland-Toolan KA, Zuccollo A, Hou X, Jiang B, et al. Polyphenols stimulate AMP-activated protein kinase, lower lipids, and inhibit accelerated atherosclerosis in diabetic LDL receptor-deficient mice. Diabetes. 2006;55:2180-91.
35
ACCEPTED MANUSCRIPT [154] Kamei Y, Miura S, Suganami T, Akaike F, Kanai S, Sugita S, et al. Regulation of SREBP1c gene expression in skeletal muscle: role of retinoid X receptor/liver X receptor and forkhead-O1 transcription factor. Endocrinology. 2008;149:2293-305.
T
[155] Aigner E, Theurl I, Haufe H, Seifert M, Hohla F, Scharinger L, et al. Copper
RI P
availability contributes to iron perturbations in human nonalcoholic fatty liver disease. Gastroenterology. 2008;135:680-8.
SC
[156] Fields M, Holbrook J, Scholfield D, Smith JC, Jr., Reiser S. Effect of fructose or starch on copper-67 absorption and excretion by the rat. J Nutr. 1986;116:625-32.
NU
[157] Aigner E, Strasser M, Haufe H, Sonnweber T, Hohla F, Stadlmayr A, et al. A role for low hepatic copper concentrations in nonalcoholic Fatty liver disease. Am J
MA
Gastroenterol. 2010;105:1978-85.
[158] Song M, Schuschke DA, Zhou Z, Chen T, Pierce WM, Jr., Wang R, et al. High fructose feeding induces copper deficiency in Sprague-Dawley rats: a novel
ED
mechanism for obesity related fatty liver. J Hepatol.56:433-40. [159] Prohaska JR, Geissler J, Brokate B, Broderius M. Copper, zinc-superoxide
PT
dismutase protein but not mRNA is lower in copper-deficient mice and mice lacking the copper chaperone for superoxide dismutase. Exp Biol Med (Maywood).
CE
2003;228:959-66.
[160] Machado MV, Ravasco P, Jesus L, Marques-Vidal P, Oliveira CR, Proenca T, et
AC
al. Blood oxidative stress markers in non-alcoholic steatohepatitis and how it correlates with diet. Scand J Gastroenterol. 2008;43:95-102. [161] Kang BP, Bansal MP, Mehta U. Hyperlipidemia and type I 5'-monodeiodinase activity: regulation by selenium supplementation in rabbits. Biol Trace Elem Res. 2000;77:231-9. [162] Clarke C, Baghdadi H, Howie AF, Mason JI, Walker SW, Beckett GJ. Selenium supplementation attenuates procollagen-1 and interleukin-8 production in fatloaded human C3A hepatoblastoma cells treated with TGFbeta1. Biochim Biophys Acta.1800:611-8. [163] Kaur HD, Bansal MP. Studies on HDL associated enzymes under experimental hypercholesterolemia: possible modulation on selenium supplementation. Lipids Health Dis. 2009;8:55. 36
ACCEPTED MANUSCRIPT [164] Dongiovanni P, Fracanzani AL, Fargion S, Valenti L. Iron in fatty liver and in the metabolic syndrome: a promising therapeutic target. J Hepatol.55:920-32. [165] Valenti L, Fracanzani AL, Dongiovanni P, Bugianesi E, Marchesini G, Manzini P,
T
et al. Iron depletion by phlebotomy improves insulin resistance in patients with
RI P
nonalcoholic fatty liver disease and hyperferritinemia: evidence from a case-control study. Am J Gastroenterol. 2007;102:1251-8.
SC
[166] Valenti L, Fracanzani AL, Bugianesi E, Dongiovanni P, Galmozzi E, Vanni E, et al. HFE genotype, parenchymal iron accumulation, and liver fibrosis in patients with
NU
nonalcoholic fatty liver disease. Gastroenterology. 2010;138:905-12. [167] Dongiovanni P, Valenti L, Ludovica Fracanzani A, Gatti S, Cairo G, Fargion S.
MA
Iron depletion by deferoxamine up-regulates glucose uptake and insulin signaling in hepatoma cells and in rat liver. Am J Pathol. 2008;172:738-47. [168] Dongiovanni P, Ruscica M, Rametta R, Recalcati S, Steffani L, Gatti S, et al.
ED
Dietary iron overload induces visceral adipose tissue insulin resistance. Am J Pathol.182:2254-63.
PT
[169] Dongiovanni P, Lanti C, Gatti S, Rametta R, Recalcati S, Maggioni M, et al. High fat diet subverts hepatocellular iron uptake determining dysmetabolic iron
AC
CE
overload. PLoS One.10:e0116855.
37
ACCEPTED MANUSCRIPT Table 1. Food bioactives for the prevention of nonalcoholic fatty liver: promising compounds and mechanisms Nutrient/bioactive Experimental model
Mechanism ↓lipogenesis [55]
HepG2 cells
↑antioxidant defence system [56]
In vivo
↓inflammation [52],[61],[62]
HFD fed mice,
↓hepatic cholesterol, TG, FFAs [57]
SC
RI P
T
In vitro
ricefish medaka (Oryzias latipes) ↓lipogenesis [58, 64]
Omega-3
↑lipolysis [58]
Wistar rat
PUFAs
NU
↓Steatosis and fibrosis [59-62] ↓lipid peroxidation [61],[62]
MA
Patients
↓Steatosis, FFAs, fasting glucose [44, 45]
Adults and children with
↓IR, hepatic steatosis, , ALT ,[49]
NAFLD
↓ inflammatory macrophage [53],[54] ↓lipid peroxidation [78]
ED
In vitro
↓collagen up-regulation [79]
stellate cells, human and mouse
↓lipogenesis [80]
PT
human fibroblast, rat hepatic
↑β-oxidation [80, 170]
CE
hepatocellular carcinoma, Hepa
In vivo
↓CD36 receptor [81]
Wistar rats, obese (ob/ob) mouse
↓oxidative stress [82]
model of NASH, guinea pigs
↓lipid peroxidation [84, 85]
Vitamin E
AC
1-6, HepG2 cells
↓fibrogenesis[84], inflammation [82, 83], lipid uptake [81] ↓Steatosis, inflammation, fibrosis [72]
Patients Adults with NASH and NAFLD Children with NAFLD
Vitamin D
In vitro
↑detoxifying enzyme [100]
HepG2 cells
↓inflammation [103]
Hepatic stellate cells
↓FXR and LXR [100] ↓fibrosis [102]
38
ACCEPTED MANUSCRIPT In vivo
↓lipogenesis [103]
Balb/C mice
↑lipolysis [103]
D-depleted rat ↓hs-CRP,↓ serum MDA[97]
T
Patients
RI P
Adults with NAFLD
↓TG synthesis [112],[113]
HepG2 cells
↓oxidative stress [113]
SC
In vitro
↑lipolysis [114],[115]
Primary rat hepatocyte
↓de novo lipogenesis [116]
In vivo db/db mice fed MCD mice fed HFD-diet
ED
Patients
↑glucose metabolism [118]
MA
Polyphenol
NU
↓lipogenesis [115]
↓liver lipid accumulation [118],[119] ↓oxidative stress, inflammation [108] ↓body weight, FFA, steatosis [109]
In vitro
↓lipogenesis [124]
PT
NAFLD patients
↑lipolysis [125]
Primary rat hepatocyte
↓oxidative stress [126]
CE
HepG2 cells
↓ROS production [126, 128] ↓lipogenesis [127]
In vivo
Obese mice
↓steatosis [128]
ApoE3 Leiden mice
↓inflammation, oxidative stress, fibrosis
AC
Anthocyanins
↓inflammation [118]
[129]
Patients
↓ liver enzymes [122]
Adults with NAFLD
↓oxidative stress, apoptosis [123]
In vitro
↓lipid accumulation, resistin[139]
HepG2
↓ inflammation, fibrogenesis [140]
HSC Silybin/silybinin
In vivo
↓IR, ALT [141]
db/db mice fed MCD
↓inflammation, oxidative stress [142]
obese fed MCD-diet mice
↓visceral fat, gluconeogenesis [143] ↑lipolysis [143]
39
ACCEPTED MANUSCRIPT
↑liver enzymes and histology [137, 138]
Patients Adults with NAFLD
↓lipogenesis [148]
HepG2 cells
↓TG synthesis [147]
RI P
T
In vitro
Primary rat hepatocyte
↓liver weight, TG accumulation [149]
SC
In vivo Resveratrol
↓lipogenesis [153]
Mice fed HFD-diet
↑lipolysis [154]
NU
Zucker rats
↓ liver enzymes, insulin resistance,
Patients
In vitro
inflammation [144, 145]
MA
Adults with NAFLD
↓fibrosis, inflammation [162]
HepG2 cells
↑antioxidant enzymes[162]
ED
Human hepatoblastoma (C3A)
Iron
In vivo
Copper deficiency
Rabbit
↓lipolysis, antioxidant system [159]
CE
PT
↑trasferrin receptor [169]
↑lipogenesis [158]
Sprague-Dawley rats
Selenium ↓TG levels [163]
AC
Minerals
Selenium
↓cholesterol levels [161] ↑antioxidant defenses [163] Iron ↑IR and dyslipidemia [168]
40
ACCEPTED MANUSCRIPT
Abbreviations: Nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis
T
(NASH), necroinflammatory score (NAS), high fat diet (HFD), free fatty acids (FFAs),
RI P
insulin resistance (IR), sterol regulatory binding protein (Srebp), fatty acid synthase (Fas), acetyl-CoA carboxylase (ACC), carnitinepalmitoyltransferase(CPT1), radical
SC
oxygen species (ROS), AMP-activated proten kinase (AMPK), peroxisome proliferatoractivated receptor (PPAR), cytochrome P450 3A4 (CYP3A4), transforming growth factor
NU
(TGF), tumor necrosis factor (TNF), cluster of differentiation 36 (CD36), Farnesoid X receptor (FXR), liver X receptor (LXR), C-reactive protein (CRP), malondialdehyde
MA
(MDA), necroinflammatory score (NAS), glutathione peroxidase (GPX), thioredoxin
AC
CE
PT
ED
reductase (TrxR1).
41
ACCEPTED MANUSCRIPT Figure 1. Molecular mechanisms explaining the hepatoprotective effect of food bioactives. Development of NAFLD/NASH is induced by different risk factors, such as Western-
T
type diet, physical inactivity and genetic predisposition. In the presence of obesity and
RI P
insulin resistance (IR) there is an increased flux of FFAs to the liver. These FFAs are stored as TG in lipid droplets leading to hepatic fat accumulation, or undergo -oxidation
SC
increasing oxidative stress and the inflammatory pathway.
The damaged hepatocyte leads to a further increase of inflammatory signalling (IL-1,
NU
TNFa, IL-6) and the recruitment of circulating and residual macrophages (Kupffer cells: KC).
MA
All of these mechanisms can directly induce the activation of hepatic stellate cells (HSC), the major cell type involved in extracellular matrix deposition and liver fibrosis. The bioactive compounds may exert beneficial effects on NAFLD development and
ED
progression by inhibiting lipogenesis, -oxidation of free fatty acids, inflammation and hepatic stellate cells activation. In the cartoon, we have listed the food bioactives
AC
CE
PT
indicating the putative mechanisms by which they may improve liver damage in NAFLD.
42