Could metabolic syndrome lead to hepatocarcinoma via non-alcoholic fatty liver disease?

It was estimated that from 2002 to 2008 the risk of developing cancer increased a quarter-fold in men and twofold in women due to excessive BMI.Obesity,metabolic syndrome and type 2 diabetes mellitus are strictly related and are key pathogenetic factors of non-alcoholic fatty liver disease(NAFLD),the most frequent liver disease worldwide.The most important consequence of the"metabolic epidemics"is the probable rise in the incidence of hepatocarcinoma(HCC),and NAFLD is the major causative factor.Adipose tissue is not merely a storage organ where lipids are preserved as an energy source.It is an active organ with important endocrine,paracrine,and autocrine actions in addition to immune functions.Adipocytes produce a wide range of hormones,cytokines,and growth factors that can act locally in the adipose tissue microenvironment and systemically.In this article,the main roles of insulin growth factor(IGF)-1 and IGF-2 are discussed.The role of IGF-2 is not only confined to HCC,but it may also act in early hepato-carcinogenesis,as preneoplastic lesions express IGF-2 mRNA.IGF-1 and IGF-2interact with specific receptors(IGF-1R and IGF-2R).IGF-1R is over-expressed in in vitro and in animal models of HCC and it was demonstrated that IGF ligands exerted their effects on HCC cells through IGF-1R and that it was involved in the degeneration of pre-neoplastic lesions via an increase in their mitotic activity.Both IGF-2R and TGFβ,a growth inhibitor,levels are reduced in human HCC compared with adjacent normal liver tissues.Another key mechanism involves peroxisome proliferator-activated receptor(PPAR)γ.In in vitro studies,PPARγinhibited various carcinomas including HCC,most probably by regulating apoptosis via the p21,p53 and p27 pathways.Finally,as a clinical consequence,to improve survival,efforts to achieve a"healthier diet"should be promoted by physicians and politicians.     

Is there any progress in the treatment of non-alcoholic fatty liver disease?

Despite the fact that non-alcoholic fatty liver disease(NAFLD) and its severe clinical form,non-alcoholic steatohepatitis,are becoming increasingly prevalent in the industrialised countries,there are no licensed pharmacological treatments for them.Weight loss and life modifications,antioxidant therapies and insulin-sensitising agents are the current treatment strategies and have all been tested with inconclusive results.Low sample numbers,inadequate treatment duration and invalid surrogate markers for treatment response might all account for these results.As NAFLD is a systemic rather than a liver disease,future trials should address the patient as a whole and also address cardiovascular risk factors.     

A lipid to treat non-alcoholic fatty liver disease - the dawn of 'lipo-rehabilitation'?

Nuclear hormone receptors regulate diverse metabolic pathways and the orphan nuclear receptor LRH-1 (also known as NR5A2) regulates bile acid biosynthesis. Structural studies have identified phospholipids as potential LRH-1 ligands, but their functional relevance is unclear. Here we show that an unusual phosphatidylcholine species with two saturated 12 carbon fatty acid acyl sidechains (dilauroyl phosphatidylcholine (DLPC)) is an LRH-1 agonist ligand in vitro. DLPC treatment induces bile acid biosynthetic enzymes in mouse liver, increases bile acid levels, and lowers hepatictriglycerides and serum glucose. DLPC treatment also decreases hepatic steatosis and improves glucose homeostasis in two mouse models of insulin resistance. Both the antidiabetic and lipotropic effects are lost in liver-specific Lrh-1 knockouts. These findings identify an LRH-1 dependent phosphatidylcholine signalling pathway that regulates bile acid metabolism and glucose homeostasis.     

What is the role of adiponectin in obesity related non-alcoholic fatty liver disease?

Non-alcoholic fatty liver disease (NAFLD) is recognized as the most common type of chronic liver disease in Western countries.Insulin resistance is a key factor in the pathogenesis of NAFLD,the latter being considered as the hepatic component of insulin resistance or obesity.Adiponectin is the most abundant adipose-specific adipokine.There is evidence that adiponectin decreases hepatic and systematic insulin resistance,and attenuates liver inflammation and fibrosis.Adiponectin generally predicts steatosis grade and the severity of NAFLD;however,to what extent this is a direct effect or related to the presence of more severe insulin resistance or obesity remains to be addressed.Although there is no proven pharmacotherapy for the treatment of NAFLD,recent therapeutic strategies have focused on the indirect upregulation of adiponectin through the administration of various therapeutic agents and/or lifestyle modifications.In this adiponectin-focused review,the pathogenetic role and the potential therapeutic benefits of adiponectin in NAFLD are analyzed systematically.     

Vitamin D: A new player in non-alcoholic fatty liver disease?

Vitamin D through its active form 1a-25-dihydroxyvtamin D[1,25(OH)2D]is a secosteroid hormone that plays a key role in mineral metabolism.Recent years have witnessed a significant scientific interest on vitamin D and expanded its actions to include immune modulation,cell differentiation and proliferation and inflammation regulation.As our understanding of the many functions of vitamin D has grown,the presence of vitamin D deficiency has become one of the most prevalent micronutrient deficiencies worldwide.Concomitantly,non-alcoholic fatty liver disease(NAFLD)has become the most common form of chronic liver disease in western countries.NAFLD and vitamin D deficiency often coexist and epidemiologic evidence has shown that both of these conditions share several cardiometabolic risk factors.In this article we provide an overview of the epidemiology and pathophysiology linking NAFLD and vitamin D deficiency,as well as the available evidence on the clinical utility of vitamin D supplementation in NAFLD.     

Increased risk of cardiovascular disease in non-alcoholic fatty liver disease: causal effect or epiphenomenon?

Non-alcoholic fatty liver disease (NAFLD), comprising a spectrum of conditions ranging from pure steatosis to steatohepatitis and cirrhosis, has reached epidemic proportions and represents the most common cause of chronic liver disease in the community. The prevalence of NAFLD has been estimated to be between 20% and 30% in the general population, but this value is much higher (∼70–80%) in type 2 diabetic patients, who are also at higher risk of developing advanced fibrosis and cirrhosis. Increasing recognition of the importance of NAFLD and its strong relationship with the metabolic syndrome has stimulated an interest in the possible role of NAFLD in the development of cardiovascular disease (CVD). Several epidemiological studies indicate that NAFLD, especially in its more severe forms, is linked to an increased risk of CVD, independently of underlying cardiometabolic risk factors. This suggests that NAFLD is not merely a marker of CVD, but may also be actively involved in its pathogenesis. The possible molecular mediators linking NAFLD and CVD include the release of pro-atherogenic factors from the liver (C-reactive protein, fibrinogen, plasminogen activator inhibitor-1 and other inflammatory cytokines) as well as the contribution of NAFLD per se to whole-body insulin resistance and atherogenic dyslipidemia, in turn favouring CVD progression. The clinical impact of NAFLD on CVD risk deserves particular attention in view of the implications for screening and surveillance strategies in the growing number of patients with NAFLD. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Chronic kidney disease in patients with non-alcoholic fatty liver disease: What the Hepatologist should know?

The association of non-alcoholic fatty liver disease (NAFLD) with several other diseases has gained increased interest during the recent years. Among them, the association with chronic kidney disease (CKD) has emerged as an important one regarding both its prevalence and significance. The early recognition of this association is important for the prognosis of patients with NAFLD and CKD. Apart from early diagnosis, the accurate assessment of renal function is also crucial in the clinical practice of hepatologists. Several methods have been used in the literature for the evaluation of kidney function in patients with NAFLD up to now. In this respect, calculators (or formulas) for the estimation of Glomerular Filtration Rate (eGFR) and Albumin to Creatinine Ratio (ACR) are simple, practical and easily available methods for this purpose. The aim of this review is to report on the epidemiology and pathophysiology of the relationship between NAFLD and CKD and to describe the different methods of kidney function assessment in patients with NAFLD. The collection of all relevant data regarding this association will provide hepatologists with pertinent knowledge on this topic and allow them to use the most accurate methods for the assessment of kidney function in these patients in their clinical practice.     

Reduced lysosomal acid lipase activity: A new marker of liver disease severity across the clinical continuum of non-alcoholic fatty liver disease?

Lysosomal acid lipase(LAL)plays a key role in intracellular lipid metabolism.Reduced LAL activity promotes increased multi-organ lysosomal cholesterol ester storage,as observed in two recessive autosomal genetic diseases,Wolman disease and Cholesterol ester storage disease.Severe liver steatosis and accelerated liver fibrosis are common features in patients with genetic LAL deficiency.By contrast,few reliable data are available on the modulation of LAL activity in vivo and on the epigenetic and metabolic factors capable of regulating its activity in subjects without homozygous mutations of the Lipase A gene.In the last few years,a less severe and non-genetic reduction of LAL activity was reported in children and adults with non-alcoholic fatty liver disease(NAFLD),suggesting a possible role of LAL reduction in the pathogenesis and progression of the disease.Patients with NAFLD show a significant,progressive reduction of LAL activity from simple steatosis to non-alcoholic steatohepatitis and cryptogenic cirrhosis.Among cirrhosis of different etiologies,those with cryptogenic cirrhosis show the most significant reductions of LAL activity.These findings suggest that the modulation of LAL activity may become a possible new therapeutic target for patients with more advanced forms of NAFLD.Moreover,the measurement of LAL activity may represent a possible new marker of disease severity in this clinical setting.