Long term prognosis of fatty liver: risk of chronic liver disease and death

Review article: diagnosis and treatment of non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is an increasingly prevalent condition affecting adults and children, leading to significant morbidity. It is often associated with the metabolic syndrome, although multiple pathogenetic mechanisms have been suggested. In the coming decades, it promises to be the leading cause of liver disease in industrial countries.

AIM

To provide a comprehensive, updated review of diagnosis and management of NAFLD and to appraise the evolution of new modalities in these areas.

METHODS

An Ovid MEDLINE search was performed to identify pertinent original research and review articles. Selected references in these articles were also evaluated.

RESULTS

The diagnosis of hepatic steatosis and steatohepatitis or non-alcoholic steatohepatitis (NASH) is not yet possible without liver biopsy. This is impractical given the large numbers affected by the condition. Current therapy has focused on improving insulin resistance and mediators of inflammation, factors probably associated with disease progression.

CONCLUSIONS

There are no proven non-invasive diagnostic modalities to distinguish NAFLD and NASH, but new biomarker panels are approximating the liver biopsy in accuracy. Therapeutic targets of drug development are in early stages, but a multifaceted approach will probably yield several treatment options in the years to come.

Nutrition in pathophysiology and treatment of nonalcoholic fatty liver disease

PURPOSE OF REVIEW

Overnutrition resulting in obesity plays a key role in nonalcoholic fatty liver disease, the major reason for abnormal liver function in many parts of the world. Currently, it is not clear which type of diet preferentially results in this common disease.

RECENT FINDINGS

Excess nutrition leads to accumulation of various lipids in the liver, where fatty acids are considered the main driving force in the disease process. A liver loaded with fat is commonly associated with insulin resistance, the key pathophysiological phenomenon observed in nonalcoholic fatty liver disease. Not surprisingly, attempts to reduce body weight and thereby total liver fat are considered the key therapeutical steps in this disorder. Although voluntary weight loss is often not successful to reverse the disease process, various surgical procedures have proven effective in reducing overweight situations and liver steatosis. Weight loss not only reduces the amount of liver fat but also might improve inflammation and fibrosis in nonalcoholic steatohepatitis.

SUMMARY

Although pharmacological approaches are eagerly awaited to achieve similar benefits; current available therapies have so far not fulfilled this expectation. Despite this frustration, such approaches are expected to be available in the near future.

Clinical trial: insulin-sensitizing agents may reduce consequences of insulin resistance in individuals with non-alcoholic steatohepatitis

BACKGROUND

Currently, although only a few therapies normalize the liver test abnormalities with/without improving the liver histology, no pharmacologic therapy has proved to be effective for the treatment of non-alcoholic steatohepatitis.

AIM

To investigate the role of insulin sensitizers in the treatment of individuals with non-alcoholic steatohepatitis (NASH).

METHODS

A total of 74 individuals with NASH (male/female, 44/30; mean age, 47.2 +/- 9.0 years) were enrolled. Participants were divided into two distinct groups: group 1 (n = 25) participants were administered a conventional diet and exercise programme while those in group 2 (n = 49) were administered the diet and exercise programme plus insulin sensitizers.

RESULTS

With respect to baseline metabolic, biochemical and histological parameters, no significant differences were observed between the two groups (P > 0.05). Insulin sensitizers significantly improved metabolic parameters (homeostasis model assessment-insulin resistance score, P < 0.05), serum aminotransferase levels [aspartate aminotransferase (AST): 45.9 +/- 24.2 to 33.3 +/- 17.7 IU/L, P < 0.01; alanine aminotransferase (ALT): 78.2 +/- 46.3 to 47.3 +/- 34.5 IU/L, P < 0.001] and histological features (median non-alcoholic fatty liver disease activity score: 5.0-3.0, P = 0.01), while diet and exercise improved serum aminotransferase levels (AST: 39.3 +/- 11.1 to 30.0 +/- 8.6 IU/L, P < 0.01; ALT: 66.9 +/- 28.9 to 42.0 +/- 16.2 IU/L, P < 0.001) at the end of the 48 weeks when compared to baseline. Insulin sensitizers improved the high-sensitivity C-reactive protein levels (P < 0.01). No serious adverse effects of insulin sensitizers were observed.

CONCLUSION

Insulin sensitizers can lead to improvement in metabolic, biochemical and histological abnormalities of NASH as a result of improved insulin sensitivity.

Non-invasive means of measuring hepatic fat content

Hepatic steatosis affects 20% to 30% of the general adult population in the western world. Currently, the technique of choice for determining hepatic fat deposition and the stage of fibrosis is liver biopsy. However, it is an invasive procedure and its use is limited, particularly in children. It may also be subject to sampling error. Non-invasive techniques such as ultrasound, computerised tomography (CT), magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy ((1)H MRS) can detect hepatic steatosis, but currently cannot distinguish between simple steatosis and steatohepatitis, or stage the degree of fibrosis accurately. Ultrasound is widely used to detect hepatic steatosis, but its sensitivity is reduced in the morbidly obese and also in those with small amounts of fatty infiltration. It has been used to grade hepatic fat content, but this is subjective. CT can detect hepatic steatosis, but exposes subjects to ionising radiation, thus limiting its use in longitudinal studies and in children. Recently, magnetic resonance (MR) techniques using chemical shift imaging have provided a quantitative assessment of the degree of hepatic fatty infiltration, which correlates well with liver biopsy results in the same patients. Similarly, in vivo (1)H MRS is a fast, safe, non-invasive method for the quantification of intrahepatocellular lipid (IHCL) levels. Both techniques will be useful tools in future longitudinal clinical studies, either in examining the natural history of conditions causing hepatic steatosis (e.g. non-alcoholic fatty liver disease), or in testing new treatments for these conditions.

Liver stiffness values in apparently healthy subjects: influence of gender and metabolic syndrome

BACKGROUND/AIMS

Liver stiffness measurement by transient elastography is a very promising non-invasive method for the diagnosis of fibrosis in chronic liver diseases. However, studies on normal values of liver stiffness in healthy subjects are still lacking. The aim of the present study was to prospectively assess liver stiffness values in the general population and to determine potential factors, which may influence these values.

METHODS

Liver stiffness measurements were performed in 429 consecutive apparently healthy subjects, without overt cause of liver disease and normal liver enzymes, undergoing a free medical check-up.

RESULTS

Mean liver stiffness value was 5.49+/-1.59 kPa. Transient elastography failure was observed in 4.6% of the cases. The failure rate increased with BMI, reaching 88% for values above 40 kg/m2. Liver stiffness values were higher in men than in women (5.81+/-1.54 vs 5.23+/-1.59 kPa, p=0.0002) and in subjects with BMI>30 kg/m2 (6.26+/-1.89 vs 5.37+/-1.51 kPa, p=0.0003). Metabolic syndrome was diagnosed in 59 (13.7%) subjects. After adjustment for gender and BMI, liver stiffness values were higher in subjects with metabolic syndrome than in those without (6.51+/-1.64 vs 5.33+/-1.51 kPa, p<0.0001).

CONCLUSIONS

Liver stiffness values in the general population are influenced independently by gender, BMI and metabolic syndrome.

Evolving trends in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common etiologies of chronic liver disease worldwide. NALFD encompasses a continuum of histological findings ranging from steatosis alone, to nonalcoholic steatohepatitis (NASH) with steatosis, inflammation, hepatocyte ballooning, fibrosis and eventually liver cirrhosis. The pathogenesis of NAFLD might be related to a deregulated cross-talk between liver and visceral adipose tissue, originating an impairment of normal insulin signaling. A better comprehension of the immunologic and metabolic roles of adipose tissue in modulating inflammatory pathways will enhance our understanding of the molecular mechanisms leading to progression of fatty liver disease. These insights, moreover, will suggest new strategies to improve insulin sensitivity and reduce obesity-associated morbidities and mortality.

Nonalcoholic fatty liver disease: from clinical recognition to treatment

Nonalcoholic fatty liver disease (NAFLD) is probably the most common spectrum of metabolic liver disease in the world, encompassing simple steatosis to steatohepatitis, advanced fibrosis, cirrhosis and hepatocellular carcinoma. NAFLD affects a significant part of the general population worldwide. The existing correlation between obesity and NAFLD in combination with the increase in the frequency of obesity in the developed world implies that the incidence and severity of NAFLD will increase in the near future. Newer data support the idea that NAFLD constitutes the more important cause of cryptogenic cirrhosis of the liver and a ground for the development of hepatocellular carcinoma. Liver biopsy remains the most specific and sensitive method to differentiate NAFLD, providing important information on the long-term prognosis of the patients. The 'two hit' hypothesis constitutes the currently prevailing theory for the development of NAFLD and nonalcoholic steatohepatitis. The first 'hit' is purported to be the increase of free fatty acids in hepatocytes, which results in a decrease of beta-oxidation. The second step includes all mechanisms contributing to the development of necroinflammation and fibrosis. Currently, an effective treatment for patients with NAFLD does not exist. Improvement in liver histology remains the primary goal of any therapeutic approach in patients with NAFLD. Viewing NAFLD in the frame of the metabolic syndrome opens the possibility that both the onset of the disease and disease progression could be prevented by changes in lifestyle. Physical exercise and a low calorie diet in combination with the gradual loss of body weight represent the cornerstone for the management of NAFLD patients.

Treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease, defined as the presence of macrovascular steatosis in the presence of less than 20 gm of alcohol ingestion per day, is the most common liver disease in the USA. It is most commonly associated with insulin resistance/type 2 diabetes mellitus and obesity. It is manifested by steatosis, steatohepatitis, cirrhosis, and, rarely, hepatocellular carcinoma.Hepatic steatosis results from an imbalance between the uptake of fat and its oxidation and export. Insulin resistance, predisposing to lipolysis of peripheral fat with mobilization to and uptake of fatty acids by the liver, is the most consistent underlying pathogenic factor. It is not known why some patients progress to cirrhosis; however, the induction of CYP 2E1 with generation of reactive oxygen species appears to be important.Treatment is directed at weight loss plus pharmacologic therapy targeted toward insulin resistance or dyslipidemia. Bariatric surgery has proved effective. While no pharmacologic therapy has been approved, emerging data on thiazolidinediones have demonstrated improvement in both liver enzymes and histology. There are fewer, but promising data, with statins which have been shown to be hepatoprotective in other liver diseases. The initial enthusiasm for ursodeoxycholic acid has not been supported by histologic studies.

Non-alcoholic fatty liver disease (NAFLD) and cardiovascular disease: an open question

AIMS

To review available data concerning the basic science and epidemiological-clinical evidence for an association of NAFLD and cardiovascular disease.

DATA SYNTHESIS

Non-alcoholic fatty liver disease (NAFLD) defines alcohol-like hepatic histological lesions seen in the non-alcoholic, insulin resistant patient representing the hepatic counterpart of the metabolic syndrome. Along with insulin resistance, additional genetic, endocrine and vascular changes together with environmental stimuli--which are also involved in the pathogenesis of atherosclerosis--play a prominent role in the development and progression of NAFLD. Clinical and epidemiological studies seem to indicate that NAFLD is associated with an increased risk for cardiovascular disease but further studies are needed to confirm the available data. The mainstay of NAFLD treatment is based on the correction of the same metabolic changes that predispose to atherosclerosis.

CONCLUSIONS

Non-invasive evaluation of risk for cardiovascular events is recommended in all individuals presenting with NAFLD and conversely, the presence of NAFLD should always be looked for in subjects with features belonging to the metabolic syndrome. Further studies are needed on the mechanisms linking fatty liver and vascular diseases.

Present and future therapeutic strategies in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is found in individuals who do not drink or abuse alcohol and represents a significant health burden for the general community. NAFLD is often associated with one or more features of the metabolic syndrome and has potential for evolution towards non-alcoholic steatohepatitis (NASH), the necro-inflammatory form of liver steatosis. The most worrisome evolutive events in a subgroup of NASH patients include advanced liver fibrosis, cirrhosis, and hepatocellular carcinoma. Pathophysiology of NAFLD/NASH is complex, but studies point to a pre-eminent role of oxidative stress and lipid peroxidation in the liver, including early mitochondrial dysfunction. Changes follow an insulin resistance status with a background of a chronic pro-inflammatory status due to an excess of visceral adiposity. Although no established therapy exists for NAFLD/NASH, potential therapeutic approaches are discussed in this review.

Nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) refers to the presence of hepatic steatosis not associated with a significant intake of ethanol. Insulin resistance is central to the pathogenesis of NAFLD; thus obesity, diabetes, and the metabolic syndrome are frequently associated with the disease. Consequently, as these metabolic conditions emerge as major health problems in Western society, it is now recognized that NAFLD is the most common chronic liver condition in the Western world. NAFLD is generally asymptomatic, although a minority of patients may present with evidence of progressive liver injury with complications of cirrhosis, liver failure, and hepatocellular carcinoma. Despite being common and potentially serious, relatively little is known about the natural history or prognostic significance of NAFLD. Although diabetes, obesity, and age are recognized risk factors for advanced liver disease, other significant factors leading to progressive liver injury remain to be identified. The treatment of NAFLD focuses upon modifying metabolic risk factors. Insulin-sensitizing and hepatoprotective drugs have been subjected to study trials, but as yet, no agent has conclusively been demonstrated to prevent disease progression. Management is further complicated by the inability to predict which patients will develop liver-related morbidity and thus benefit from treatment.

Obesity and nonalcoholic fatty liver disease

With the increasing prevalence of obesity and type 2 diabetes mellitus in the general population, nonalcoholic fatty liver disease (NAFLD) has become a common diagnosis in clinical practice. Insulin resistance and oxidative stress play an important role in NAFLD development and progression. NAFLD affects one in three adults and one in 10 children/adolescents in the United States. Mortality in patients with NAFLD is significantly higher than in the general population of same age and gender with liver-related complications. Lifestyle intervention may improve NAFLD, but medications that increase insulin sensitivity and the antioxidant defenses in the liver deserve evaluation in carefully controlled trials.

Nonalcoholic fatty liver disease: from pathogenesis to patient care

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in Western countries. It encompasses a wide spectrum of liver lesions, from pure steatosis to end-stage liver disease with cirrhosis and hepatocellular carcinoma. Nonalcoholic steatohepatitis corresponds only to one stage of NAFLD. As NAFLD can be considered a liver manifestation of the metabolic syndrome, its prevalence is high in obese people and in patients who have type 2 diabetes-insulin resistance is one of the key elements of the pathogenesis of NAFLD. This disease is often asymptomatic in the absence of decompensated cirrhosis, but should be suspected in patients with elevated aminotransferase levels or radiological evidence of a fatty liver or hepatomegaly. Liver fibrosis is associated with age over 50 years, obesity, diabetes and high triglyceride levels. Liver biopsy is the only way to assess the histologic features of necrotic inflammation and fibrosis that define nonalcoholic steatohepatitis and to determine its probable prognosis. The prognosis is good for pure steatosis, whereas the presence of necrotic inflammation is associated with a significant risk of progression to cirrhosis and, possibly, hepatocellular carcinoma. Lifestyle changes, such as dietary modifications and exercise, are recommended. To date, there have been very few randomized, placebo-controlled trials of drug treatments for NAFLD.

Elevated levels of serum advanced glycation end products in patients with non-alcoholic steatohepatitis

BACKGROUND AND AIM

Advanced glycation end products (AGE), senescent macroprotein derivatives formed at an accelerated rate in diabetes, play important roles in the pathogenesis of diabetic vascular complications. Recently, AGE have also been found to be involved in insulin resistance. Although non-alcoholic steatohepatitis (NASH) is generally considered a hepatic manifestation of insulin resistance, there are no reports showing the link of AGE to NASH. The aim of this study was to evaluate the clinical significance of AGE in patients with NASH.

METHODS

Glyceraldehyde-derived AGE levels were assayed from serum obtained from 106 patients: 66 with NASH, 10 with simple steatosis, and 30 controls.

RESULTS

Serum glyceraldehyde-derived AGE levels (U/mL) were significantly elevated in NASH patients (9.78 +/- 3.73) compared with simple steatosis (7.17 +/- 2.28, P = 0.018) or healthy controls (6.96 +/- 2.36, P = 0.003). Moreover, these were inversely correlated with adiponectin, an adipocytokine with insulin-sensitizing and anti-inflammatory properties. In addition, immunohistochemistry of glyceraldehyde-derived AGE showed intense staining in the livers of NASH patients.

CONCLUSION

The present data suggest that the sustained increase of glyceraldehyde-derived AGE could at least in part contribute to the pathogenesis of NASH. The serum glyceraldehyde-derived AGE level may be a useful biomarker for discriminating NASH from simple steatosis.

Non-alcoholic fatty liver disease in the Asia-Pacific region: definitions and overview of proposed guidelines

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder in Western industrialized countries, affecting 20-40% of the general population. Large population-based surveys in China, Japan, and Korea indicate that the prevalence of NAFLD is now 12% to 24% in population subgroups, depending on age, gender, ethnicity, and location (urban versus rural). There is strong evidence that the prevalence of NAFLD has increased recently in parallel with regional trends in obesity, type 2 diabetes, and metabolic syndrome; and that further increases are likely. The relationship between NAFLD, central obesity, diabetes, and metabolic syndrome is clearly evident in retrospective and prospective Asian studies, but the strength of association with these metabolic risk factors is only appreciated when regional definitions of anthropometry are used. Pathological definition of NAFLD, particularly its activity and the extent of liver fibrosis, requires histological examination, but liver biopsy is often not appropriate in this disorder for logistic reasons. An alternative set of operational definitions is proposed here. Clinicians need guidelines as how best to diagnose and manage NAFLD and its associated metabolic disorders in countries with scant healthcare resources. The Asia-Pacific Working Party (APWP) for NAFLD was convened to collate evidence and deliberate these issues. Draft proposals were presented and discussed at Asia-Pacific Digestive Week at Cebu, Philippines, in late November 2006, and are published separately in this issue of the Journal as an Executive Summary. The present document reviews the reasoning and evidence behind the APWP-NAFLD proposals for definition, assessment, and management of NAFLD in the Asia-Pacific region.

Managing nonalcoholic fatty liver disease: recommendations for family physicians

OBJECTIVE

To review evidence on the diagnosis and management of nonalcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease in human beings.

SOURCES OF INFORMATION

The literature was searched for clinical trials and review articles on NAFLD. Levels I and II evidence indicates the benefit of both lifestyle and pharmacologic interventions for NAFLD and nonalcoholic steatohepatitis (NASH).

MAIN MESSAGE

Scientific evidence does not currently support systematic screening for NAFLD. Both NAFLD and NASH are frequently discovered in overweight and obese patients with asymptomatic elevation of serum aminotransferase levels. Ultrasonography detects the presence of a fatty liver, but is unreliable for detecting and quantifying liver fibrosis. Patients with NAFLD should be monitored for possible progression to NASH, particularly if they have diabetes or metabolic syndrome. Although diet and exercise are the mainstays of treatment, medication might be warranted if an appropriate diet and regular physical activity do not improve biochemical markers and liver morphology. Referral for liver biopsy and further evaluation should be considered for those at higher risk of developing NASH.

CONCLUSION

Although most patients with NAFLD have a benign course, some progress to NASH, liver cirrhosis, and hepatocellular carcinoma. These patients should be carefully monitored for progression of disease and treated for associated metabolic disturbances. An integrated approach to care is essential.

GI epidemiology: nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a common diagnosis in clinical practice. Insulin resistance and oxidative stress play an important role in NAFLD development and progression.

AIM

To review the data available on the epidemiology and natural history of NAFLD as well as the risk factors for its development and the areas where future research is necessary. RESULTS /CONCLUSIONS: NAFLD may affect individuals of any age range and race/ethnicity. NAFLD affects one in three adults and one in ten children/adolescents in the United States. Mortality in patients with NAFLD is significantly higher than in the general population of same age and gender with liver-related complications being a common cause of death. Liver-related morbidity and mortality in NAFLD occurs when the disease has progressed to advanced fibrosis and cirrhosis. Further studies are necessary to determine the impact of NAFLD on health-related quality of life and resources utilization, and to the extent to which preventing the development of the metabolic syndrome would prevent NAFLD development and reduce liver-related morbidity and mortality. Lifestyle intervention may improve NAFLD, but medications that increase insulin sensitivity and the antioxidant defenses in the liver deserve evaluation in carefully controlled trials.

The NAFLD fibrosis score: a noninvasive system that identifies liver fibrosis in patients with NAFLD

Patients with nonalcoholic fatty liver disease (NAFLD) and advanced liver fibrosis are at the highest risk for progressing to end-stage liver disease. We constructed and validated a scoring system consisting of routinely measured and readily available clinical and laboratory data to separate NAFLD patients with and without advanced fibrosis. A total of 733 patients with NAFLD confirmed by liver biopsy were divided into 2 groups to construct (n = 480) and validate (n = 253) a scoring system. Routine demographic, clinical, and laboratory variables were analyzed by multivariate modeling to predict presence or absence of advanced fibrosis. Age, hyperglycemia, body mass index, platelet count, albumin, and AST/ALT ratio were independent indicators of advanced liver fibrosis. A scoring system with these 6 variables had an area under the receiver operating characteristic curve of 0.88 and 0.82 in the estimation and validation groups, respectively. By applying the low cutoff score (-1.455), advanced fibrosis could be excluded with high accuracy (negative predictive value of 93% and 88% in the estimation and validation groups, respectively). By applying the high cutoff score (0.676), the presence of advanced fibrosis could be diagnosed with high accuracy (positive predictive value of 90% and 82% in the estimation and validation groups, respectively). By applying this model, a liver biopsy would have been avoided in 549 (75%) of the 733 patients, with correct prediction in 496 (90%).

CONCLUSION

a simple scoring system accurately separates patients with NAFLD with and without advanced fibrosis, rendering liver biopsy for identification of advanced fibrosis unnecessary in a substantial proportion of patients.

Effects of bariatric surgery on nonalcoholic fatty liver disease: preliminary findings after 2 years

BACKGROUND AND AIM

Although nonalcoholic fatty liver disease (NAFLD) is very common among morbidly obese patients, the effect of weight loss after bariatric surgery on inflammation and fibrosis related to NAFLD is still a matter of debate. The aim of this study was to evaluate the impact of Roux-en-Y gastric bypass (RYGB) surgery on NAFLD with a follow up of 2 years.

METHODS

Eighteen consecutive NAFLD patients with body mass index >40 kg/m(2) undergoing gastroplasty with RYGB were enrolled, and wedge liver biopsy was obtained at the operation. After 2 years, these patients underwent percutaneous liver biopsy.

RESULTS

At baseline, 67% of patients had nonalcoholic steatohepatitis (NASH) and 33% had steatosis, according to the NASH Clinical Research Network Scoring System (NAS) for biopsy. Cirrhosis was present in 5.5% of the patients with NASH. After a mean excess weight loss of 60%, steatosis disappeared in 84% and fibrosis disappeared in 75% of the patients. Hepatocellular ballooning disappeared in 50%. A slight lobular inflammatory infiltrate remained in 81%, apparently unrelated to fatty degeneration. As liver biochemical variables had been found within normal limits in 92.3% of patients at initial biopsy, no difference was found 2 years later. Lipid profile and blood sugar plasma concentration were closer to normal in all patients after 2 years (P < 0.05).

CONCLUSIONS

Aspects of NAFLD including steatohepatitis improved significantly with massive weight loss at 2 years after RYGB surgery. No patient in this series had progression of hepatic fibrosis.

Noninvasive assessment of fibrosis in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)

The term "non-alcoholic fatty liver disease" (NAFLD) encompasses a wide range of pathological conditions ranging from accumulation of fat (fatty liver) to various degrees of inflammation and fibrosis (NASH), and finally to cryptogenic cirrhosis and its clinical sequelae (HCC, liver decompensation). The progression from one stage to the next can be triggered by genetic and environmental factors alone and also through their interaction. Fatty liver is known to follow a benign course, whereas the presence of inflammation, ballooning degeneration, and fibrosis, which are typical features of NASH, can lead to cirrhosis. Despite the serious risks associated with NASH, there are few tools for monitoring the progression of the disease and identification of high-risk patients. The aim of this article is to review the pros and cons of some noninvasive methods for assessing liver fibrosis in NASH.

Epidemiology and natural history of NAFLD and NASH

Understanding of the epidemiology and natural history of non-alcoholic fatty liver disease (NAFLD) has increased; it is the most common form of chronic liver disease in the Western world and increasing in importance in other parts of the world. Prevalence is expected to increase as obesity and diabetes epidemics evolve. The natural history of NAFLD depends on the histologic subtype. Those who have simple hepatic steatosis or nonspecific inflammation generally have a benign long-term prognosis, whereas non-alcoholic steatohepatitis (NASH) can progress to cirrhosis. NASH-related cirrhosis may have a similar prognosis as cirrhosis from other causes, leading to liver failure or hepatocellular carcinoma.

Hypertension and fatty liver: guilty by association?

Essential hypertension is associated with the metabolic syndrome, insulin resistance and the development of fatty liver. Fatty liver disease is a spectrum of liver diseases ranging from simple hepatic steatosis through steato-hepatitis to cirrhosis and hepatoma. The purpose of this review is to discuss the evidence for an association between essential hypertension and non-alcoholic fatty liver disease, and to consider the diagnosis and management of non-alcoholic fatty liver disease. We conclude that it is important to consider the diagnosis of fatty liver disease in hypertensive patients, to measure the liver function tests at diagnosis and not to ignore minor elevations of serum aminotransferases. Hypertensive patients with raised liver enzymes should be referred for further assessment, particularly if risk factors for progressive liver disease, such as obesity and diabetes, are present.

Pathogenesis of non-alcoholic steatohepatitis: human data

Non-alcoholic fatty liver disease (NAFLD) has moved rapidly to the forefront of clinical disease, with a prevalence of 30% in the adult United States population and a definite but yet uncertain rate of progression to cirrhosis and end-stage liver disease. This disease has an impact on all areas of clinical medicine, with increasing prevalence and adversity. It is essential to understand the pathophysiologic mechanisms involved in NAFLD, so that therapeutic strategies can be developed. Although fatty liver may be caused by other factors, this review concentrates on fatty liver associated with insulin resistance, sometimes referred to as the primary form.

Role of liver biopsy and serum markers of liver fibrosis in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is common and may progress to end-stage liver disease. Liver-related morbidity and mortality occur almost exclusively in patients whose disease progresses to advanced fibrosis and cirrhosis. Presence and severity of liver fibrosis seem the most important indicators of long-term prognosis. Clinical and biochemical variables may help select NAFLD patients in whom liver biopsy may provide the most prognostic information. Some serum markers of liver fibrosis and imaging techniques aimed at measuring liver stiffness are under investigation as tools to determine severity of liver fibrosis in patients who have NAFLD, but none of them yet can replace liver biopsy.

Diabetes and liver disease: an ominous association

Diabetes mellitus and advanced liver disease are associated with each other more frequently than expected by chance, and such an association carries a significant risk of morbidity and mortality. A metabolic pathway leading to advanced liver disease via fatty liver and steatohepatitis has been demonstrated, further supporting the possibility that cirrhosis may be a late complication of diabetes. In addition, an interaction between hepatitis C virus (HCV) and insulin resistance increases the overall prevalence of associated diseases, through largely unidentified mechanisms. Extensive prospective monitoring of non-alcoholic fatty liver disease cases, analysis of insulin signaling in HCV-infected patients using molecular biology techniques, and intervention studies, will help to clarify the mechanisms of action of the possible clinical strategies, the predictive value of biochemical, histological, and clinical markers, and the effectiveness of treatments available.

Histological assessment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is an important complication of the metabolic syndrome, which is becoming an increasingly common cause of chronic liver disease. Histological changes typically mainly affect perivenular regions of the liver parenchyma and include an overlapping spectrum of steatosis, steatohepatitis and persinusoidal or pericellular fibrosis, in some cases leading to cirrhosis. Once cirrhosis has developed, typical hepatocellular changes are often no longer conspicuous, leading to such cases being mistakenly diagnosed as 'cryptogenic'. Portal inflammation, ductular reaction and periportal fibrosis can also be seen as part of the morphological spectrum of NAFLD, particularly in the paediatric population. Hepatocellular carcinoma has also been described as a complication of NAFLD-associated cirrhosis. NAFLD is also an important cofactor in other chronic liver diseases, especially hepatitis C. Histological assessments have an important role to play in the diagnosis and management of NAFLD. These include making the potentially important distinction between simple steatosis and steatohepatitis and providing pointers to the aetiology, including cases where a dual pathology exists. A number of systems have been devised for grading and staging the severity of fatty liver disease. These require further evaluation, but have a potentially important role to play in determining prognosis and monitoring therapeutic responses.

Treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is common and may progress to cirrhosis and its complications. The pathogenesis of steatosis and cellular injury is thought to be related mostly to insulin resistance and oxidative stress. Therefore, management entails identification and treatment of metabolic risk factors, improving insulin sensitivity, and increasing antioxidant defences in the liver. Weight loss and exercise improve insulin sensitivity. Bariatric surgery may improve liver histology in patients with morbid obesity. Insulin sensitising drugs showed promise in pilot trials as have a number of hepatoprotective agents. Further randomised, well controlled trials are required to determine the efficacy of these drugs.

Beyond randomized controlled trials: a critical comparison of trials with nonrandomized studies

Observational analogs of randomized clinical trials (RCTs) are well accepted in the study of disease risk factors, diagnosis, and prognosis. There is controversy about observational studies when the focus is on the intended benefit due to lack of blinding and poor control for unmeasured confounding. Well-designed randomized clinical trials are costly both in time and money. Therefore, existing databases are used increasingly and are often the only feasible source with which to examine delayed health effects. We reviewed the reasons for possible discrepancies between RCTs and observational studies. There can be different patient populations, differences in therapeutic regimen, control of confounding, follow-up, measuring outcome, and differences arising from the intention-to-treat analysis. Observational studies cannot replace trials, nor do trials make observational studies unnecessary. Both designs are susceptible to particular bias, so neither provides perfect information.

Expression of p53, Bax and Bcl-2 proteins in hepatocytes in non-alcoholic fatty liver disease

AIM: To analyze the protein expression essential for apoptosis in liver steatosis.

METHODS: The expression of proapoptotic proteins p53, Bax, and antiapoptotic Bcl-2 in hepatocytes with steatosis (SH) and without steatosis (NSH) was evaluated in 84 patients at various stages of non-alcoholic fatty liver disease (NAFLD).

RESULTS: Immunohistochemical staining of liver tissue showed the activation of p53 protein in SH and NSH with increased liver steatosis, diminished Bcl-2 and slightly decreased Bax protein. Positive correlation was found between the stage of liver steatosis with p53 expression in SH (r = 0.54, P < 0.01) and NSH (r = 0.49, P < 0.01). The antiapoptotic protein Bcl-2 was diminished together with the advancement of liver steatosis, especially in non-steatosed hepatocytes (r =0.43, P < 001).

CONCLUSION: Apoptosis is one of the most important mechanisms leading to hepatocyte elimination in NAFLD. The intensification of inflammation in NAFLD induces proapoptotic protein p53 with the inhibition of antiapoptotic Bcl-2.

Long-term follow-up of patients with NAFLD and elevated liver enzymes

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of elevated liver enzymes in patients of developed countries. We determined the long-term clinical and histological courses of such patients. In a cohort study, 129 consecutively enrolled patients diagnosed with biopsy-proven NAFLD were reevaluated. Survival and causes of death were compared with a matched reference population. Living NAFLD patients were offered repeat liver biopsy and clinical and biochemical investigation. Mean follow-up (SD) was 13.7 (1.3) years. Mortality was not increased in patients with steatosis. Survival of patients with nonalcoholic steatohepatitis (NASH) was reduced (P = .01). These subjects more often died from cardiovascular (P = .04) and liver-related (P = .04) causes. Seven patients (5.4%) developed end-stage liver disease, including 3 patients with hepatocellular carcinoma. The absence of periportal fibrosis at baseline had a negative predictive value of 100% in predicting liver-related complications. At follow-up, 69 of 88 patients had diabetes or impaired glucose tolerance. Progression of liver fibrosis occurred in 41%. These subjects more often had a weight gain exceeding 5 kg (P = .02), they were more insulin resistant (P = .04), and they exhibited more pronounced hepatic fatty infiltration (P = .03) at follow-up. In conclusion, NAFLD with elevated liver enzymes is associated with a clinically significant risk of developing end-stage liver disease. Survival is lower in patients with NASH. Most NAFLD patients will develop diabetes or impaired glucose tolerance in the long term. Progression of liver fibrosis is associated with more pronounced insulin resistance and significant weight gain.

[Epidemiology and natural history of primary nonalcoholic fatty liver disease]

The clinical impact of nonalcoholic fatty liver disease depends on its prevalence and natural history. The prevalence in the adult population is estimated to be about 23% and is on the increase. Thus, it has become the most common cause of persistent elevated liver enzymes, chronic liver disease, and cryptogenic cirrhosis in developed countries. The increasing prevalence of nonalcoholic fatty liver disease, which is approaching epidemic proportions, is parallel to that of other disorders associated with insulin resistance, especially obesity and type 2 diabetes mellitus. This entity occurs in men and women equally and in all age groups. The natural history is poorly defined mainly due to the scarcity of histologic follow-up studies. Although steatosis alone has a more benign clinical course, steatohepatitis is a progressive fibrotic disease, in which cirrhosis and liver-related death occur in a similar way to other causes of chronic liver diseases. Progression seems to be mainly dependent on the severity of histological damage at diagnosis, but age older than 40 years, obesity, and type 2 diabetes have also been associated with an increased risk of liver fibrosis and progression to cirrhosis.

Colloid scintigraphy in non-alcoholic steatohepatitis: a conventional diagnostic method for an emerging disease

AIM

Non-alcoholic steatohepatitis (NASH) is a progressive liver disease characterized by diffuse fatty infiltration and Kupffer cell dysfunction which contributes to its pathogenesis. Since the liver biopsy, which is considered the 'gold standard' in diagnosing NASH, has some limitations other imaging methods have been explored as alternatives. Colloid scintigraphy is a good method reflecting Kupffer cell activity and we found it worthwhile to evaluate this technique in NASH. We aimed to present the common scintigraphic features and their clinicopathologic correlations in NASH.

METHODS

Twenty-two new patients (11 female, mean age 43.7+/-10.8) with biopsy-proven NASH underwent colloid liver scintigraphy. The dynamic, static and SPECT images were performed after intravenous injection of 185 MBq Tc tin colloid. Hepatic perfusion, blood pool clearance time, colloid shift to spleen and bone marrow were assessed and liver right/left lobe ratio was calculated.

RESULTS

The values calculated on static and tomographic (SPECT) images showed good correlation. Liver right/left lobe ratio was altered in all patients. Blood pool clearance time was prolonged in seven (32%) but hepatic perfusion was normal in all patients. Colloid shift to the spleen was observed in 55% of patients using SPECT analysis. No correlation between scintigraphy parameters and histological or biochemical findings were observed.

CONCLUSION

Altered liver right/left lobe ratio was the universal finding in all our NASH patients. Other common scintigraphic features of NASH include colloid shift to spleen and prolonged blood pool clearance time. Liver scintigraphy might be a promising non-invasive tool in the follow-up of NASH patients in therapeutic trials.

NAFLD in children: a prospective clinical-pathological study and effect of lifestyle advice

Nonalcoholic fatty liver disease (NAFLD), a common cause of chronic liver disease in adults, is incompletely characterized in children. We conducted a prospective study to better characterize the clinical presentation of NAFLD in children and to determine the effect of lifestyle advice in the management of pediatric NAFLD. From June 2001 to April 2003, 84 children (age 3-18.8 yr) who had elevated aminotransferases and the diagnosis of NAFLD confirmed via liver biopsy underwent a 2-hour oral glucose tolerance test and a 12-month program of lifestyle advice consisting of diet and physical exercise. Thirty-four (40.5%) patients were obese (body mass index [BMI] >97th percentile), and 43 (51.2%) were overweight (BMI 85th-97th percentile). Ten (12%) had abnormal glucose tolerance; 10 (12%) had elevated triglycerides, cholesterol, or both; and all had normal blood pressure. Most children (67/84, 80%) were insulin-resistant, including the 7 children with normal BMI (<85th percentile). Increased liver fibrosis was present in 49 (58.1%) patients and was independently associated with obesity (OR 2.7, 95% CI 1.2-6.2) and age (1-year increase; OR 1.2, 95% CI 1.04-1.5). A 12-month program with diet and physical exercise resulted in a significant decrease in BMI, and levels of fasting glucose, insulin, lipids, and liver enzymes, as well as liver echogenicity on ultrasonography. In conclusion, children with NAFLD are almost always insulin-resistant regardless of BMI. Obesity and older age are independently associated with increased liver fibrosis. A simple lifestyle advice program significantly improves insulin resistance, and the liver disease in pediatric NAFLD.

Non-alcoholic fatty liver disease (NAFLD)--a novel common aspect of the metabolic syndrome

Non-alcoholic fatty liver disease (NAFLD) is emerging as one of the most common liver disorders claiming the urgent attention of both medical professionals and the public sphere because of the imminent epidemic of advanced liver injury that appendages epidemic of obesity. Recent research reveals simple triglyceride accumulation in hepatocytes (i.e., liver steatosis) frequently becoming complicated by inflammation (i.e., non-alcoholic steatohepatitis, or NASH) that may progress into more advanced stages of the disease including cirrhosis or, eventually, hepatocellular carcinoma. The exact mechanisms of the progression of NAFLD into overt NASH and advanced disease stages are largely unknown. There is urgent need in terms of both intensive research pursuits and effective practical measures to deal with this common threat.

In vivo assessment of liver cell apoptosis as a novel biomarker of disease severity in nonalcoholic fatty liver disease

In patients with nonalcoholic fatty liver disease (NAFLD), a liver biopsy remains the only reliable way to differentiate simple steatosis from nonalcoholic steatohepatitis (NASH). Noninvasive methods are urgently needed. Increasing evidence suggests hepatocyte apoptosis is a key mediator of liver injury in NAFLD. The aim of this study was to quantify hepatocyte apoptosis in plasma from patients with NAFLD and correlate it with histological severity. Plasma was obtained from 44 consecutive patients with suspected NAFLD at the time of liver biopsy. Histology was assessed blindly. Caspase-3-generated cytokeratin-18 fragments were measured in situ via immunohistochemistry and in vivo using a novel enzyme-linked immunosorbent assay. Plasma cytokeratin-18 fragments were markedly increased in patients with NASH compared with patients with simple steatosis or normal biopsies (median [interquartile range]: 765.7 U/L [479.6-991.1], 202.4 U/L [160.4-258.2], 215.5 U/L [150.2-296.2], respectively; P < .001). Cytokeratin-18 fragment levels independently predicted NASH (OR 1.95; 95% CI 1.18-3.22; P = .009 for every 50 U/L increase). A cutoff value of 395 U/L calculated using the receiver operating characteristic curve approach showed a specificity of 99.9%, a sensitivity of 85.7%, and positive and negative predictive values of 99.9% and 85.7%, respectively, for the diagnosis of NASH. In conclusion, these findings strongly suggest that determination of hepatocyte caspase activation in the blood is a strong and independent predictor of NASH in human subjects. These data highlight the potential usefulness of this test as a noninvasive diagnostic means of determining histological disease severity in patients with NAFLD.

Systemic inflammation in nonalcoholic fatty liver disease is characterized by elevated levels of CCL2

BACKGROUND/AIMS

To elucidate the role of systemic inflammation in nonalcoholic fatty liver disease (NAFLD).

METHODS

Serum samples in 47 patients with histologically verified NAFLD (22 with simple steatosis and 25 with nonalcoholic steatohepatitis [NASH]), and in 30 age-, sex- and ethnicity-matched healthy controls, were assessed for (i) general markers of inflammation (C-reactive protein [CRP], tumor necrosis factor [TNF]-alpha, and interleukin [IL]-6), (ii) chemokines (CC-chemokine ligand [CCL] 2/monocyte chemoattractant protein [MCP]-1, CCL19 and CCL21), (iii) adipocytokines related to insulin resistance and inflammation (adiponectin and leptin) and (iv) a marker of oxidative stress (8-isoprostane-F2alpha).

RESULTS

Serum levels of several inflammatory cytokines were increased in NAFLD as compared to controls, and IL-6 (P=0.017), CCL2/MCP-1 (P=0.008) and CCL19 (P=0.001), but not CRP (P=0.199), remained elevated also after correction for sex, body mass index (BMI) and age. Comparing NASH with simple steatosis, levels of TNF-alpha (P=0.024) and CCL2/MCP-1 (P=0.012) were elevated and adiponectin (in women) (P=0.001) were decreased also after adjustment for sex, BMI and presence of the metabolic syndrome.

CONCLUSIONS

Our results indicate that patients with NAFLD are characterized by a low-grade systemic inflammation. The high CCL2/MCP-1 levels in NASH might be of importance for the conversion from simple steatosis to NASH.

Nonalcoholic fatty liver disease and liver transplantation

Nonalcoholic fatty liver disease affects a substantial proportion of the general population worldwide. This high prevalence of nonalcoholic fatty liver disease has important consequences in the donor selection process for liver transplantation, and in the posttransplant period given the high recurrence rate of disease. This paper reviews the prevalence of nonalcoholic fatty liver disease, its progressive potential, and the implications of this liver condition in both the pre- and post-liver transplantation setting.

The value of combining serum alanine aminotransferase levels and body mass index to predict mortality and medical costs: a 10-year follow-up study of National Health Insurance in Shiga, Japan

BACKGROUND

Evidence suggests that the predictive value of serum alanine aminotransferase (ALT) levels for prognosis, measured by indices such as all-cause mortality and medical costs, may be modified by body mass index (BMI). However, the relationship between serum ALT and BMI has not been satisfactorily elucidated.

METHODS

Four thousand, five hundred and twenty-four community dwelling Japanese National Health Insurance beneficiaries, 40-69 years old, were classified into five categories according to their serum ALT levels (IU/L) (ALT<20, 20< or =ALT<30, 30< or =ALT<40, 40< or =ALT<50 and 50< or =ALT) and followed for 10 years. Hazard ratios for all-cause mortality, with reference to the lowest serum ALT category, and medical costs per person were evaluated for each serum ALT category after analyzing interactions between serum ALT levels and BMI for all-cause mortality and for medical costs.

RESULTS

A significant interaction between serum ALT levels and BMI was observed. In participants below the median BMI, positive, graded relationships were identified between serum ALT levels and all-cause mortality as well as between serum ALT levels and personal medical costs. The multivariate-adjusted hazard ratio in the "50< or =ALT" category showed an approximately 8-fold increase. However, in the participants at or above the median BMI, no significant relationships between serum ALT levels and all-cause mortality or personal medical costs were identified.

CONCLUSIONS

In these Japanese participants, the predictive value of serum ALT levels for prognosis was more evident if BMI was taken into account. A combination of high serum ALT levels and below median BMI was associated with excess mortality and medical costs.

Long-term prognosis of nonalcoholic fatty liver disease: is pharmacological therapy actually necessary?

BACKGROUND AND AIM

Nonalcoholic fatty liver disease (NAFLD) comprises a wide spectrum of liver injury, ranging from steatosis and steatohepatitis to cirrhosis. Reasons for the different natural course in individuals with NAFLD are still unclear. The aim of this study was to describe the natural course of disease in individuals with NAFLD who did not receive pharmacological therapy.

METHODS

A total of 27 individuals with NAFLD (male/female ratio: 10/17, mean age 49.7 years) were prospectively enrolled. Management after diagnosis consisted of establishment of an appropriate diet and exercise (walking and jogging) program, treatment of associated metabolic conditions such as diabetes and dyslipidemia, and discontinuation of potentially hepatotoxic drugs if the patient was taking these. Liver tests were performed at diagnosis and at 3-month intervals during the follow-up period. Mean follow-up period was 43.3 months (range 36-49 months).

RESULTS

From baseline to the end of the follow-up period, although there was no significant difference observed in terms of the mean body mass index, serum aminotransferase levels significantly improved (48.8+/-29.9 U/L to 31.6+/-16.0 U/L for aspartate aminotransferase [AST] and 66.3+/-38.3 U/L to 39.6+/-22.9 U/L for alanine aminotransferase [ALT]; P<0.05). No significant differences in platelet counts, serum albumin level or prothrombin time were observed (P>0.05). No patient developed signs of advanced liver disease during the follow-up period.

CONCLUSION

A treatment strategy comprising diet, exercise and management of associated metabolic conditions is associated with improvement in aminotransferases among patients with NAFLD. Further investigation is needed to examine the long-term efficacy of this approach on liver histology and clinical outcomes.

The diagnostic value of biomarkers (SteatoTest) for the prediction of liver steatosis

Background

Biopsy is the usual gold standard for liver steatosis assessment. The aim of this study was to identify a panel of biomarkers (SteatoTest), with sufficient predictive values, for the non-invasive diagnosis of steatosis in patients with or without chronic liver disease. Biomarkers and panels were assessed in a training group of consecutive patients with chronic hepatitis C and B, alcoholic liver disease, and non-alcoholic fatty liver disease, and were validated in two independent groups including a prospective one. Steatosis was blindly assessed by using a previously validated scoring system.

Results

310 patients were included in the training group; 434 in three validation groups; and 140 in a control group. SteatoTest was constructed using a combination of the 6 components of FibroTest-ActiTest plus body mass index, serum cholesterol, triglycerides, and glucose adjusted for age and gender. SteatoTest area under the ROC curves was 0.79 (SE = 0.03) in the training group; 0.80 (0.04) in validation group 1; 0.86 (0.03) in validation group 2; and 0.72 (0.05) in the validation group 3 – all significantly higher than the standard markers: γ-glutamyl-transpeptidase or alanine aminotransferase. The median SteatoTest value was 0.13 in fasting controls; 0.16 in non-fasting controls; 0.31 in patients without steatosis; 0.39 in grade 1 steatosis (0–5%); 0.58 in grade 2 (6–32%); and 0.74 in grade 3–4 (33–100%). For the diagnosis of grade 2–4 steatosis, the sensitivity of SteatoTest at the 0.30 cut-off was 0.91, 0.98, 1.00 and 0.85 and the specificity at the 0.70 cut-off was 0.89, 0.83, 0.92, 1.00, for the training and three validation groups, respectively.

Conclusion

SteatoTest is a simple and non-invasive quantitative estimate of liver steatosis and may reduce the need for liver biopsy, particularly in patients with metabolic risk factor.

Abnormal glucose tolerance is a predictor of steatohepatitis and fibrosis in patients with non-alcoholic fatty liver disease

OBJECTIVE

The majority of patients with non-alcoholic fatty liver disease (NAFLD) have simple steatosis. A minority, however, present with non-alcoholic steatohepatitis (NASH), a condition that can lead to advanced fibrosis and cirrhosis. The frequencies of NASH and fibrosis among patients with NAFLD and sustained elevation of liver function tests (LFT) are uncertain. Our aim was to estimate these frequencies. We characterize a population with NAFLD, with special emphasis on insulin resistance and the metabolic syndrome, and study possible predictors for different stages of the disease.

MATERIAL AND METHODS

All referred patients with sustained elevation of LFT, radiological evidence or clinical suspicion of fatty liver, and absence of other liver disease, were invited to participate in our study in the period June 2002 to December 2004.

RESULTS

Of 129 patients who met the inclusion criteria, 88 underwent liver biopsy. NAFLD was verified in 83 of them. Among these patients, 59 (71%) had the metabolic syndrome, 41 (49%) had NASH and 36 (43%) had fibrosis. Abnormal glucose tolerance (T2DM or impaired glucose tolerance) was the only independent risk factor for NASH (OR: 3.14; 95% CI: 1.20-8.23). Independent predictors for fibrosis were abnormal glucose tolerance (OR: 3.83; 95% CI: 1.29-11.40) and body mass index (OR: 1.20; 95% CI: 1.06-1.36) per kg/m2.

CONCLUSIONS

Both NASH and fibrosis are frequently present among patients with NAFLD and sustained elevation of LFT. The probability of these potentially progressive stages of NAFLD increases with the presence of abnormal glucose tolerance.

Treatment strategies in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is an increasingly recognized health problem. Increased fat accumulation in the liver is observed in 20-30% of the population in the Western world, and in approximately 10% of this cohort it is associated with nonalcoholic steatohepatitis, which is characterized by inflammation and fibrosis. Disease presentation of NAFLD ranges from asymptomatic disease to cirrhosis with the complication of liver failure and hepatocellular carcinoma. NAFLD is suspected on the basis of various clinical aspects (an elevated alanine aminotransferase concentration, presence of obesity and diabetes) that alone are not sufficient to establish diagnosis or prognosis. The major diagnostic procedure is liver biopsy, which allows assessment of liver injury. In most cases, NAFLD is associated with insulin resistance, which is therefore the target of most current NAFLD treatment modalities. Various treatment strategies such as weight loss and/or exercise, thiazolidinediones, metformin, lipid-lowering agents and antioxidants have been studied. So far, no single intervention has convincingly improved liver histology. It is recommended that patients at high risk of developing advanced liver disease, and who are not part of controlled studies, should receive nutritional counseling and take physical exercise to achieve moderate weight loss and improve insulin sensitivity.

Rat sinusoidal liver endothelial cells (SECs) produce pro-fibrotic factors in response to adducts formed from the metabolites of ethanol

Previous studies with alcohol-associated malondialdehyde-acetaldehyde (MAA)-modified proteins have demonstrated an increase in the expression of adhesion molecules, and the secretion of pro-inflammatory cytokines/chemokines by rat sinusoidal liver endothelial cells (SECs). However, no studies have been initiated to examine the effects of MAA-modified proteins on the expression of the extracellular matrix (ECM) protein, fibronectin and its isoforms. For these studies, SECs were isolated from the liver of normal rats, and exposed to MAA-modified bovine serum albumin (MAA-Alb). At selected time points, the total plasma and cellular fibronectin were determined by Western blot. Injection of rat liver via the mesenteric vein with MAA-Alb was performed in an effort to evaluate the potential in vivo role of MAA-modified proteins in the development of fibrosis. Expression of both plasma and cellular fibronectin was significantly increased over controls in the MAA-Alb stimulated SECs (>3-fold). Importantly, the isotype of fibronectin secreted was determined to be of the EIIIA variant and not EIIIB. These data were confirmed using RT-PCR procedures on liver tissue from; isolated SECs, and from an in vivo animal model wherein MAA-Alb was administered via the mesenteric vein. Thus, these studies demonstrate that MAA-modified proteins initiate a pro-fibrogenic response by initiating the expression of the fibronectin EIIIA isoform by SECs.

Review article: the metabolic syndrome and non-alcoholic fatty liver disease

Metabolic syndrome represents a common risk factor for premature cardiovascular disease and cancer whose core cluster includes diabetes, hypertension, dyslipidaemia and obesity. The liver is a target organ in metabolic syndrome patients in which it manifests itself with non-alcoholic fatty liver disease spanning steatosis through hepatocellular carcinoma via steatohepatitis and cirrhosis. Given that metabolic syndrome and non-alcoholic fatty liver disease affect the same insulin-resistant patients, not unexpectedly, there are amazing similarities between metabolic syndrome and non-alcoholic fatty liver disease in terms of prevalence, pathogenesis, clinical features and outcome. The available drug weaponry for metabolic syndrome includes aspirin, metformin, peroxisome proliferator-activated receptor agonists, statins, ACE (angiotensin I-converting enzyme) inhibitors and sartans, which are potentially or clinically useful also to the non-alcoholic fatty liver disease patient. Studies are needed to highlight the grey areas in this topic. Issues to be addressed include: diagnostic criteria for metabolic syndrome; nomenclature of non-alcoholic fatty liver disease; enlargement of the clinical spectrum and characterization of the prognosis of insulin resistance-related diseases; evaluation of the most specific clinical predictors of metabolic syndrome/non-alcoholic fatty liver disease and assessment of their variability over the time; characterization of the importance of new risk factors for metabolic syndrome with regard to the development and progression of non-alcoholic fatty liver disease.

Nonalcoholic fatty liver disease in the pediatric population: a review

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease is a common condition that may progress to end stage liver disease. It is closely associated with obesity and insulin resistance, two conditions whose prevalence is increasing dramatically in children. This could potentially make nonalcoholic fatty liver disease the most common liver disease in the pediatric population. This review will focus on the current knowledge regarding the epidemiology, clinical presentation, diagnosis, pathogenesis, and management of nonalcoholic fatty liver disease in children.

RECENT FINDINGS

Recent studies suggest that nonalcoholic fatty liver disease is an increasingly recognized condition during childhood, especially in overweight and obese children. Although limited information is currently available on the natural history of the disease in the pediatric population, few cross-sectional studies and a single longitudinal cohort study with follow up data up to 16 years, showed that as in adults, nonalcoholic fatty liver disease in children may have a progressive clinical course with the development of cirrhosis. Emerging data from small pilot studies suggest weight loss through lifestyle modifications as well as insulin sensitizing and antioxidant medications may be of benefit. Moreover, recent advances in the understanding of nonalcoholic fatty liver disease pathogenesis may result in novel therapeutic targets to treat this disease.

SUMMARY

Nonalcoholic fatty liver disease is probably the most common form of chronic liver disease in children and may continue to rise with the increasing prevalence of childhood obesity and metabolic syndrome. Recent studies have provided new insights regarding this condition in children. There is still much progress to be made in terms of the description of pediatric nonalcoholic fatty liver disease, its demographics, pathogenesis, and treatment as well as natural history and long-term prognosis.