Pediatric nonalcoholic fatty liver disease: overview with emphasis on histology

Nonalcoholic fatty liver disease(NAFLD) is a disease in which excessive fat accumulates in the liver of a patient without a history of alcohol abuse.This disease includes simple steatosis and nonalcoholic steatohepatitis(NASH).NAFLD/NASH is recognized as a hepatic manifestation of metabolic syndrome.In recent years,pediatric NAFLD has increased in line with the increased prevalence of pediatric obesity.The estimated prevalence of pediatric NAFLD is 2.6%-9.6%,and it is associated with sex,age,and ethnicity.W...     

Current pharmacological therapies for nonalcoholic fatty liver disease/nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease(NAFLD)/nonalcoholic steatohepatitis(NASH) is considered to be a hepatic manifestation of metabolic syndrome, and its incidence is rapidly increasing worldwide. It is currently the most common chronic liver disease. NASH can progress to liver cirrhosis and hepatocellular carcinoma, and may result in liver-related death. Currently, the principal treatment for NAFLD/NASH is lifestyle modification by diet and exercise. However, pharmacological therapy is indispensable because obese patients with NAFLD often have difficulty maintaining improved lifestyles. The pathogenesis of NAFLD/NASH has not been completely elucidated. However, insulin resistance, inflammatory cytokines, and oxidative stress are thought to be important in the development and/or progression of the disease. Currently, insulin sensitizers(thiazolidinediones) and antioxidants(vitamin E) seem to be the most promising therapeutic agents for NAFLD/NASH, and lipid-lowering drugs, pentoxifylline, angiotensin receptor blockers, and n-3 polyunsaturated fatty acids also have promise. However, there is a lack of consensus regarding the most effective and appropriate pharmacotherapy for NAFLD/NASH. Animal experiments suggest that herbal medicines and natural products may be promising therapeutic agents for NAFLD/NASH, but their efficacy and safety are yet to be investigated in human studies. In this paper, we review the existing and potential pharmacological therapies for NAFLD/NASH.     

Fructose as a key player in the development of fatty liver disease

We aimed to investigate whether increased consumption of fructose is linked to the increased prevalence of fatty liver.The prevalence of nonalcoholic steatohepatitis(NASH) is 3% and 20% in nonobese and obese subjects,respectively.Obesity is a low-grade chronic inflam-m-atory condition and obesity-related cytokines such as interleukin-6,adiponectin,leptin,and tumor necrosis factor-α may play important roles in the developm-ent of nonalcoholic fatty liver disease(NAFLD).Additionally,the prevalence of NASH associated with both cirrhosis and hepatocellular carcinom-a was reported to be high am-ong patients with type 2 diabetes with or without obesity.Our research group previously showed that consumption of fructose is associated with adverse alterations of plasma lipid profiles and metabolic changes in m-ice,the Am-erican Lifestyle-Induced Obesity Syndrom-e m-odel,which included consum-ption of a high-fructose corn syrup in amounts relevant to that consum-ed by som-e Am-ericans.The observation reinforces the concerns about the role of fructose in the obesity epidem-ic.Increased availability of fructose(e.g.,high-fructose corn syrup) increases not only abnorm-al glucose flux but also fructose m-etabolism-in the hepatocyte.Thus,the anatomic position of the liver places it in a strategic buffering position for absorbed carbohydrates and am-ino acids.Fructose was previously accepted as a beneficial dietary com-ponent because it does not stim-ulate insulin secretion.However,since insulin signaling plays an important role in central m-echanism-s of NAFLD,this property of fructose m-ay be undesirable.Fructose has a selective hepatic m-etabolism,and provokes a hepatic stress response involving activation of c-Jun N-term-inal kinases and subsequent reduced hepatic insulin signaling.As high fat diet alone produces obesity,insulin resistance,and som-e degree of fatty liver with m-inim-al inflam-m-ation and no fibrosis,the fast food diet which includes fructose and fats produces a gene expression signature of increased hepatic     

Clinical approaches to non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD)ranges from simple steatosis to nonalcoholic steatohepatitis(NASH),leading to fibrosis and potentially cirrhosis,and it is one of the most common causes of liver disease worldwide.NAFLD is associated with other medical conditions such as metabolic syndrome,obesity,cardiovascular disease and diabetes.NASH can only be diagnosed through liver biopsy,but noninvasive techniques have been developed to identify patients who are most likely to have NASH or fibrosis,reducing the need for liver biopsy and risk to patients.Disease progression varies between individuals and is linked to a number of risk factors.Mechanisms involved in the pathogenesis are associated with diet and lifestyle,influx of free fatty acids to the liver from adipose tissue due to insulin resistance,hepatic oxidative stress,cytokines production,reduced very low-density lipoprotein secretion and intestinal microbiome.Weight loss through improved diet and increased physical activity has been the cornerstone therapy of NAFLD.Recent therapies such as pioglitazone and vitamin E have been shown to be beneficial.Omega 3 polyunsaturated fatty acids and statins may offer additional benefits.Bariatric surgery should be considered in morbidly obese patients.More research is needed to assess the impact of these treatments on a long-term basis.The objective of this article is to briefly review the diagnosis,management and treatment of this disease in order to aid clinicians in managing these patients.     

Limitations of liver biopsy and non-invasive diagnostic tests for the diagnosis of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis

It is estimated that 30%of the adult population in Japan is affected by nonalcoholic fatty liver disease(NAFLD).Fatty changes of the liver are generally diagnosed using imaging methods such as abdominal ultrasonography(US)and computed tomography(CT),but the sensitivity of these imaging techniques is low in cases of mild steatosis.Alanine aminotransferase levels may be normal in some of these patients,warranting the necessity to establish a set of parameters useful for detecting NAFLD,and the more severe form of the disease,nonalcoholic steatohepatitis(NASH).Although liver biopsy is currently the gold standard for diagnosing progressive NASH,it has many drawbacks,such as sampling error,cost,and risk of complications.Furthermore,it is not realistic to perform liver biopsies on all NAFLD patients.Diagnosis of NASH using various biomarkers,scoring systems and imaging methods,such as elastography,has recently been attempted.The NAFIC score,calculated from the levels of ferritin,fasting insulin,and typeⅣcollagen 7S,is useful for the diagnosis of NASH,while the NAFLD fibrosis score and the FIB-4 index are useful for excluding NASH in cases of advanced fibrosis.This article reviews the limitations and merits of liver biopsy and noninvasive diagnostic tests in the diagnosis of NAFLD/NASH.     

Probiotics as a complementary therapeutic approach in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD) is currently recognized as one of the most common causes of chronic liver disease. It involves a spectrum of conditionsthat include pure steatosis without inflammation, steatohepatitis, fibrosis and cirrhosis. The key factor in the pathophysiology of NAFLD is insulin resistance that determines lipid accumulation in the hepatocytes and, thus, oxidative stress, which is followed by inflammatory response. However, NAFLD pathogenesis is still largely unknown and has been extensively investigated. Although life style modification with the aim of losing weight has been advocated to treat this disorder, its effectiveness is limited; additionally, there is no specific pharmacologic treatment until nowadays. Recent evidence suggests that the gut microbiota may play a role in the development of insulin resistance, hepatic steatosis, necroinflammation and fibrosis. Differences in gut microbiota between NAFLD patients and lean individuals as well as presence of small intestinal bacterial overgrowth in NAFLD subjects have been demonstrated. Furthermore, some data indicate that the immunoregulatory effects of probiotics may be beneficial in NAFLD treatment as they modulate the intestinal microbiota; improve epithelial barrier function and strengthen the intestinal wall decreasing its permeability; reduce bacterial translocation and endotoxemia; improve intestinal inflammation; and reduce oxidative and inflammatory liver damage. In this article, we review the clinical trials on the use of probiotics in the treatment of NAFLD and discuss the effects of these agents and their efficacy as an emerging therapeutic resource to treat NAFLD patients.     

Molecular pathogenesis and clinical conse-quences of iron overload in liver cirrhosis

BACKGROUND: The liver, as the main iron storage compart-ment and the place of hepcidin synthesis, is the central organ involved in maintaining iron homeostasis in the body. Exces-sive accumulation of iron is an important risk factor in liver disease progression to cirrhosis and hepatocellular carcinoma. Here, we review the literature on the molecular pathogenesis of iron overload and its clinical consequences in chronic liver diseases.
DATA SOURCES: PubMed was searched for English-language articles on molecular genesis of primary and secondary iron overload, as well as on their association with liver disease pro-gression. We have also included literature on adjuvant thera-peutic interventions aiming to alleviate detrimental effects of excessive body iron load in liver cirrhosis.
RESULTS: Excess of free, unbound iron induces oxidative stress, increases cell sensitivity to other detrimental factors, and can directly affect cellular signaling pathways, resulting in accelerated liver disease progression. Diagnosis of liver cirrhosis is, in turn, often associated with the identiifcation of a pathological accumulation of iron, even in the absence of genetic background of hereditary hemochromatosis. Iron depletion and adjuvant therapy with antioxidants are shown to cause signiifcant improvement of liver functions in patients with iron overload. Phlebotomy can have beneifcial effects on liver histology in patients with excessive iron accumulation combined with compensated liver cirrhosis of different etiology.
CONCLUSION: Excessive accumulation of body iron in liver cirrhosis is an important predictor of liver failure and avail-able data suggest that it can be considered as target for adju-vant therapy in this condition.     

Inhibition of apoptosis in the management of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in the developed world. The pathogenesis of NAFLD is multifactorial, involving obesity, insulin resistance, inflammation and oxidative stress. Accordingly, several treatments targeting these pathways have been evaluated in patients with NAFLD but have either shown limited efficacy or an unfavorable safety profile. On the other hand, increased hepatocyte apoptosis also appears to be implicated in the development and progression of NAFLD and recent pilot studies suggest that inhibition of apoptosis might represent a useful approach in this disease. However, several issues pertaining both to the efficacy and safety of this new class of agents remain unresolved and larger studies are required to clarify the role of this therapeutic modality in the management of NAFLD.     

Overview of screening methods for fatty liver disease in children

The prevalence of obesity and obesity related comorbidities including diabetes and nonalcoholic fatty liver disease (NAFLD) has been rising globally. Nonalcoholic fatty liver disease is emerging as a common liver disease among adults which can lead to the eventua development of complications including cirrhosis and hepatocellular carcinoma. With the rise of obesity in children, the development of detection methods for the presence of NAFLD is becoming imperative. Although the gold standard for diagnosis is liver biopsy, practica issues limit pediatric use and warrant development of noninvasive or minimally invasive screening tools for the detection and staging of NAFLD. A variety of diagnostic methods have been studied including use aminotransferases, imaging studies and serologic markers which have some population-based limitations. Additional factors such as gender and ethnicity may also play a role in the screening of NAFLD in pediatric population studies.     

Oxidative stress and antioxidants in hepatic pathogenesis

Long term hepatitis B virus (HBV) infection is a major risk factor in pathogenesis of chronic liver diseases,including hepatocellular carcinoma (HCC). The HBV encod-ed proteins,hepatitis B virus X protein and preS,appear to contribute importantly to the pathogenesis of HCC. Both are associated with oxidative stress,which can damage cellular molecules like lipids,proteins,and DNA during chronic infection. Chronic alcohol use is another important factor that contributes to oxidative stress in the liver. Previous studies reported that treatment with antioxidants,such as curcumin,silymarin,green tea,and vitamins C and E,can protect DNA from damage and regulate liver pathogenesis-related cascades by reducing reactive oxygen species. This review summarizes some of the relationships between oxidative stress and liver pathogenesis,focusing upon HBV and alcohol,and suggests antioxidant therapeutic approaches.     

Soft drinks consumption and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD) is a common clinical condition which is associated with metabolic syndrome in 70% of cases.Inappropriate dietary fat intake,excessive intake of soft drinks,insulin resistance and increased oxidative stress combine to increase free fatty acid delivery to the liver,and increased hepatic triglyceride accumulation contributes to fatty liver.Regular soft drinks have high fructose corn syrup which contains basic sugar building blocks,fructose 55% and glucose 45%.Soft drinks...     

Histopathology of nonalcoholic fatty liver disease

Histological analysis of liver biopsies remains a standard against which other methods of assessment for the presence and amount of hepatic injury due to nonalcoholic fatty liver disease(NAFLD) are measured.Histological evaluation remains the sole method of distinguishing steatosis from advanced forms of NAFLD,i.e.nonalcoholic steatohepatitis(NASH) and fibrosis.Included in the lesions of NAFLD are steatosis,lobular and portal inflammation,hepatocyte injury in the forms of ballooning and apoptosis,and fibros...     

Dysregulation of iron and copper homeostasis in nonalcoholic fatty liver

Elevated iron stores as indicated by hyperferritinemiawith normal or mildly elevated transferrin saturation a n d m o s t l y m i l d h e p a t i c i r o n d e p o s i t i o n a r e a characteristic finding in subjects with non-alcoholic fatty liver disease(NAFLD). Excess iron is observed in approximately one third of NAFLD patients and is commonly referred to as the "dysmetabolic iron overload syndrome". Clinical evidence suggests that elevated body iron stores aggravate the clinical course of NAFLD with regard to liver-related and extrahepatic disease complications which relates to the fact that excess iron catalyses the formation of toxic hydroxylradicals subsequently resulting in cellular damage. Iron removal improves insulin sensitivity, delays the onset of type 2 diabetes mellitus, improves pathologic liver function tests and likewise ameliorates NAFLD histology. Several mechanisms contribute to pathologic iron accumulation in NAFLD. These include impaired iron export from hepatocytes and mesenchymal Kupffer cells as a consequence of imbalances in the concentrations of iron regulatory factors, such as hepcidin, cytokines, copper or other dietary factors. This review summarizes the knowledge about iron homeostasis in NAFLD and the rationale for its therapeutic implications.     

Recent advances in dietary supplementation,in treating non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD) is currently known as the most common liver problem, characterized by excessive lipid accumulation in hepatocytes,which may progress to other liver diseases such as nonalcoholic steatohepatitis, hepatic tissue fibrosis, livercirrhosis, and failure or hepatocellular carcinoma. Since NAFLD is positively associated with the development of obesity, insulin resistance, and ultimately type 2 diabetes mellitus, it is often regarded as the hepatic manifestation of the metabolic syndrome. No pharmacologic treatment has yet been proven for this disease. For most patients with presumed or confirmed NAFLD, the only proven strategy is to offer lifestyle advice that can lead to sustained weight loss. Since insulin resistance, oxidative stress, inflammation, and necro-apoptosis are involved in NAFLD pathogenesis, it seems that every potential therapeutic agent should target one or some of these pathologic events. There are many well known anti-oxidants, anti-inflammatory, and insulin sensitizer dietary supplements which have shown beneficial effects on NAFLD improvement in animal and human studies. The purpose of this review is to explore the existing evidences on dietary supplements considered to have hepatoprotective properties, and to present some proposed mechanisms by which they may protect against NAFLD.     

Roles of liver innate immune cells in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common liver disease in the United States and other developed countries and is expected to increase in the next few years. Emerging data suggest that some patients with NAFLD may progress to nonalcoholic steatohepatitis (NASH), cirrhosis and even hepatocellular carcinoma. NAFLD can also promote the development and progression of disease in other organ systems, such as the cardiovascular and endocrine (i.e. diabetes) systems. Thus, understanding th...     

Role of endoplasmic reticulum stress in the pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD)has emerged as a common public health problem in recent decades.However,the underlying mechanisms leading to the development of NAFLD are not fully understood.The endoplasmic reticulum(ER)stress response has recently been proposed to play a crucial role in both the development of steatosis and progression to nonalcoholic steatohepatitis.ER stress is activated to regulate protein synthesis and restore homeostatic equilibrium when the cell is stressed due to the accumulation of unfolded or misfolded proteins.However,delayed or insufficient responses to ER stress may turn physiological mechanisms into pathological consequences,including fat accumulation,insulin resistance,inflammation,and apoptosis,all of which play important roles in the pathogenesis of NAFLD.Therefore,understanding the role of ER stress in the pathogenesis of NAFLD has become a topic of intense investigation.This review highlights the recent findings linking ER stress signaling pathways to the pathogenesis of NAFLD.     

Nonalcoholic fatty liver disease and vascular disease:State-of-the-art

Nonalcoholic fatty liver disease(NAFLD), the most common of chronic liver disease in Western Country, is closely related to insulin resistance and oxidative stress and includes a wide spectrum of liver diseases ranging from steatosis alone, usually a benign and non-progressive condition, to nonalcoholic steatohepatitis(NASH), which may progress to liver fibrosis and cirrhosis. NAFLD is considered the hepatic manifestation of the metabolic syndrome with which shares several characteristics, however recent data suggest that NAFLD is linked to increased cardiovascular risk independently of the broad spectrum of risk factors of metabolic syndrome. Accumulating evidence suggests that the clinical burden of NAFLD is not restricted to liver-related morbidity and mortality, with the majority of deaths in NAFLD patients related to cardiovascular disease and cancer and not to the progression of liver disease. Retrospective and prospective studies provide evidence of a strong association between NAFLD and subclinical manifestation of atherosclerosis(increased intima-media thickness, endothelial dysfunction, arterial stiffness, impaired left ventricular function and coronary calcification). A general agreement emerging from these studies indicates that patients with NASH are at higher risk of cardiovascular diseases than those with simple steatosis, emphasizing the role of chronic inflammation in the pathogenesis of atherosclerosis of these patients. It is very likely that the different mechanisms involved in the pathogenesis of atherosclerosis in patients with NAFLD have a different relevance in the patients according to individual genetic background. In conclusion, in the presence of NAFLD patients should undergo a complete cardiovascular evaluation to prevent future atherosclerotic complications. Specific lifestyle modification and aggressive pharmaceutical modification will not only reduce the progression of liver disease, but also reduce morbidity for cardiovascular disease improving overall prognosis and survival.     

Alcoholic liver injury： Pathological features and models—Role of alcohol in the regulation of iron metabolism

Patients with alcoholic liver disease frequently exhibit increased body iron stores, as reflected by elevated serum iron indices (transferrin saturation, ferritin) and hepatic iron concentration. Even mild to moderate alcohol consumption has been shown to increase the prevalence of iron overload. Moreover, increased hepatic iron content is associated with greater mortality from alcoholic cirrhosis, suggesting a pathogenic role for iron in alcoholic liver disease. Alcohol increases the severity of disease in patients with genetic hemochromatosis, an iron overload disorder common in the Caucasian population. Both iron and alcohol individually cause oxidative stress and lipid peroxidation, which culminates in liver injury. Despite these observations, the underlying mechanisms of iron accumulation and the source of the excess iron observed in alcoholic liver disease remain unclear. Over the last decade, several novel iron-regulatory proteins have been identified and these have greatly enhanced our understanding of iron metabolism. For example, hepcidin, a circulatory antimicrobial peptide synthesized by the hepatocytes of the liver is now known to play a central role in the regulation of iron homeostasis. This review attempts to describe the interaction of alcohol and iron-regulatory molecules. Understanding these molecular mechanisms is of considerable clinical importance because both alcoholic liver disease and genetic hemochromatosis are common diseases, in which alcohol and iron appear to act synergistically to cause liver injury.     

Nonalcoholic fatty liver disease:Updates in noninvasive diagnosis and correlation with cardiovascular disease

Nonalcoholic fatty liver disease(NAFLD)refers to the accumulation of fat(mainly triglycerides)within hepatocytes.Approximately 20%-30%of adults in the general population in developed countries have NAFLD;this trend is increasing because of the pandemicity of obesity and diabetes,and is becoming a serious public health burden.Twenty percent of individuals with NAFLD develop chronic hepatic inflammation[nonalcoholic steatohepatitis(NASH)],which can be associated with the development of cirrhosis,portal hypertension,and hepatocellular carcinoma in a minority of patients.And thus,the detection and diagnosis of NAFLD is important for general practitioners.Liver biopsy is the gold standard for diagnosing NAFLD and confirming the presence of NASH.However,the invasiveness of this procedure limits its application to screening the general population or patients with contraindications for liver biopsy.The development of noninvasive diagnostic methods for NAFLD is of paramount importance.This review focuses on the updates of noninvasive diagnosis of NAFLD.Besides,we review clinical evidence supporting a strong association between NAFLD and the risk of cardiovascular disease because of the cross link between these two disorders.     

Non-invasive methods for the diagnosis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD) is the commonest chronic liver disease and includes simple steatosis and nonalcoholic steatohepatitis(NASH). Since NASH progresses to cirrhosis more frequently and increases liver-related and cardiovascular disease risk substantially more than simple steatosis, there is a great need to differentiate the two entities. Liver biopsy is the gold standard for the diagnosis of NAFLD but its disadvantages, including the risk of complications and sampling bias, stress the need for developing alternative diagnostic methods. Accordingly, several non-invasive markers have been evaluated for the diagnosis of simple steatosis and NASH, including both serological indices and imaging methods. The present review summarizes the current knowledge on the role of these markers in the diagnosis of NAFLD. Current data suggest that ultrasound and the fibrosis-4 score are probably the most appealing methods for detecting steatosis and for distinguishing NASH from simple steatosis, respectively, because of their low cost and relatively high accuracy. However, currently available methods, both serologic and imaging, cannot obviate the need for liver biopsy for diagnosing NASH due to their substantial false positive and false negative rates. Therefore, the current role of these methods is probably limited in patients who are unwilling or have contraindications for undergoing biopsy.