Nonalcoholic fatty liver disease： An overview of current insights in pathogenesis, diagnosis and treatment

Estimates of people suffering from overweight （one billion） and obesity （300 million） are increasing. The accumulation of triglycerides in the liver, in the absence of excess alcohol intake, has been described in the early sixties. It was not until 1980, however, that Ludwig et al named this condition nonalcoholic steatohepatitis （NASH）. Subsequently, nonalcoholic fatty liver disease （NAFLD） has been used as a general name for conditions ranging from simple steatosis through steatohepatitis to end-stage liver disease （cirrhosis）. Many studies have demonstrated the significant correlation with obesity and insulin resistance. Other studies have revealed a signifi- cant correlation between hepatic steatosis, cardiovascu- lar disease and increased intima-media thickness. WHO estimated that at least two million patients will develop cirrhosis due to hepatic steatosis in the years to come. Longitudinal cohort studies have demonstrated that those patients with cirrhosis have a similar risk to devel- op hepatocellular carcinoma as those with other causes of cirrhosis. Taken all together, NAFLD has become the third most important indication for liver transplantation. There- fore, training programmes in internal medicine, gastroen- terology and hepatology should stress the importance of diagnosing this entity and treat properly those at risk for developing complications of portal hypertension and con- comittant cardiovascular disease. This review will focus on the clinical characteristics, pathophysiology, imaging tech- niques and the readily available therapeutic options.     

Nonalcoholic fatty liver disease prevalence in an Italian cohort of patients with hidradenitis suppurativa: A multi-center retrospective analysis

BACKGROUND Nonalcoholic fatty liver disease(NAFLD) includes two distinct conditions, with different histologic features and prognosis: non-alcoholic fatty liver(NAFL) and non-alcoholic steatohepatitis(NASH). Furthermore, NASH is the more aggressive necro-inflammatory form, which may accumulate fibrosis and result in End stage liver disease(ESLD). NAFLD is also linked to systemic inflammatory conditions such as psoriasis. NAFLD is currently the most common cause of ESLD in Western countries, becoming a serious public health concern.Hidradenitis suppurativa(HS) is a systemic inflammatory/autoinflammatory disease of the terminal follicular epithelium of the apocrine gland with a prevalence of 0.05% to 4.10%. Due to its systemic inflammatory behavior several comorbidities were recently associated, however liver ones were scarcely assessed.AIM To evaluate the prevalence and characteristics of NASH/NAFL in HS patients.METHODS This retrospective study is a sub-analysis of a larger study carried out in 4 Italian dermatological centers. In this cohort, there were 83 patients: 51 patients with HS only, 20 patients with HS/NAFL and 12 with HS/NASH.RESULTS Inflammatory comorbidities were present in 3.9% of HS only patients, 25% of HS/NAFL patients and 58.3% of HS/NASH patients(P 0.001). Similarly, mean Autoinflammatory Disease Damage Index(ADDI) was significantly higher among patients with HS/NASH(5.3 ± 2.2, P 0.001) compared to patients with HS/NAFL or HS only(2.8 ± 1.6 and 2.6 ± 1.4 respectively). Furthermore, ADDI correlates with IHS4 in HS, HS/NAFL and HS/NASH. Diabetic patients have higher Hurley score than not diabetic ones. Ultrasound examination was significantly different in the three groups.CONCLUSION HS patients displayed a high prevalence of NASH/NAFLD and ultrasound examination should be particularly addressed to patients that display high ADDI scores.     

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...     

儿童非酒精性脂肪性肝病研究进展

非酒精性脂肪性肝病（NAFLD）是导致儿童及青少年肝病的最常见原因。近年来,由于肥胖症的发病率逐年升高,NAFLD的患病率也明显增加。对于非酒精性脂肪性肝炎（NASH）的确诊及分级依赖于组织活检。一些非创伤性的检测指标及影像技术的发展有助于在NAFLD高风险人群中进行大范围筛查。在儿童患者中存在两种组织类型不同的NASH,其临床特征及人群特征也有差异。至今并未有儿童NAFLD的最佳治疗方案,但研究人员认为生活方式干预如饮食控制或锻炼具有一定作用。维生素E和二甲双胍对儿童NAFLD的治疗作用正处于临床研究之中。     

Nonalcoholic fatty liver disease: pharmacologic and surgical options

The last decade has seen many studies examining the prevalence and natural history of NAFLD in the United States and it is clear that this disease is likely to be an important cause of liver-related morbidity in the future. Several pharmacologic therapies have shown some promise; currently, vitamin E and insulin-sensitizing agents such as pioglitazone can be considered in appropriate cases. Conservative measures to promote weight loss still have a role to play, but the obesity epidemic in the Western World has reached such proportions that bariatric surgery is proving to be an attractive option for patients with a BMI greater than 35 to 40 kg/m2. Well-designed prospective studies are required to ensure that all of these therapies are safe and effective in the long term. Newer agents will likely be investigated as the pathogenesis of NAFLD and fibrosis progression in NASH are further elucidated.     

Nonalcoholic fatty liver disease and cardiovascular disease

Nonalcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD) are two diseases that are common in the general population. To date, many studies have been conducted and demonstrate a direct link between NAFLD and CVD, but the exact mechanisms for this complex relationship are not well established. A systematic search of the PubMed database revealed that several common mechanisms are involved in many of the local and systemic manifestations of NAFLD and lead to an increased cardiovascular risk. The possible mechanisms linking NAFLD and CVD include inflammation, oxidative stress, insulin resistance, ectopic adipose tissue distribution, dyslipidemia, endothelial dysfunction, and adiponectin, among others. The clinical implication is that patients with NAFLD are at an increased risk of CVD and should undergo periodic cardiovascular risk assessment.     

Noninvasive evaluation of nonalcoholic fatty liver disease: Current evidence and practice

With the increasing number of individuals with diabetes and obesity,nonalcoholic fatty liver disease(NAFLD) is becoming increasingly prevalent,affecting one-quarter of adults worldwide. The spectrum of NAFLD ranges from simple steatosis or nonalcoholic fatty liver(NAFL) to nonalcoholic steatohepatitis(NASH). NAFLD, especially NASH, may progress to fibrosis, leading to cirrhosis and hepatocellular carcinoma. NAFLD can impose a severe economic burden,and patients with NAFLD-related terminal or deteriorative liver diseases have become one of the main groups receiving liver transplantation. The increasing prevalence of NAFLD and the severe outcomes of NASH make it necessary to use effective methods to identify NAFLD. Although recognized as the gold standard, biopsy is limited by its sampling bias, poor acceptability, and severe complications, such as mortality, bleeding, and pain. Therefore, noninvasive methods are urgently needed to avoid biopsy for diagnosing NAFLD. This review discusses the current noninvasive methods for assessing NAFLD,including steatosis, NASH, and NAFLD-related fibrosis, and explores the advantages and disadvantages of measurement tools. In addition, we analyze potential noninvasive biomarkers for tracking disease processes and monitoring treatment effects, and explore effective algorithms consisting of imaging and nonimaging biomarkers for diagnosing advanced fibrosis and reducing unnecessary biopsies in clinical practice.     

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.     

Non-alcoholic fatty liver disease: The diagnosis and management

Non-alcoholic fatty liver disease(NAFLD) is now the most frequent chronic liver disease that occurs across all age groups and is recognized to occur in 14%-30% of the general population, representing a serious and growing clinical problem due to the growing prevalence of obesity and overweight. Histologically, it resembles alcoholic liver injury but occurs in patients who deny significant alcohol consumption. NAFLD encompasses a spectrum of conditions, ranging from benign hepatocellular steatosisto inflammatory nonalcoholic steatohepatitis, fibrosis, and cirrhosis. The majority of hepatocellular lipids are stored as triglycerides, but other lipid metabolites, such as free fatty acids, cholesterol, and phospholipids, may also be present and play a role in disease progression. NAFLD is associated with obesity and insulin resistance and is considered the hepatic manifestation of the metabolic syndrome, a combination of medical conditions including type 2 diabetes mellitus, hypertension, hyperlipidemia, and visceral adiposity. Confirmation of the diagnosis of NAFLD can usually be achieved by imaging studies; however, staging the disease requires a liver biopsy. Current treatment relies on weight loss and exercise, although various insulin-sensitizing agents, antioxidants and medications appear promising. The aim of this review is to highlight the current information regarding epidemiology, diagnosis, and management of NAFLD as well as new information about pathogenesis, diagnosis and management of this disease.     

Noninvasive biomarkers in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide among children and adolescents. It encompasses a spectrum of disease, from its mildest form of isolated steatosis, to nonalcoholic steatohepatitis (NASH) to liver fibrosis and cirrhosis, or end-stage liver disease. The early diagnosis of pediatric NAFLD is crucial in preventing disease progression and in improving outcomes. Currently, liver biopsy is the gold standard for diagnosing NAFLD. However, given its invasive nature, there has been significant interest in developing noninvasive methods that can be used as accurate alternatives. Here, we review noninvasive biomarkers in pediatric NAFLD, focusing primarily on the diagnostic accuracy of various biomarkers as measured by their area under the receiver operating characteristic, sensitivity, and specificity. We examine two major approaches to noninvasive biomarkers in children with NAFLD. First, the biological approach that quantifies serological biomarkers. This includes the study of individual circulating molecules as biomarkers as well as the use of composite algorithms derived from combinations of biomarkers. The second is a more physical approach that examines data measured through imaging techniques as noninvasive biomarkers for pediatric NAFLD. Each of these approaches was applied to children with NAFLD, NASH, and NAFLD with fibrosis. Finally, we suggest possible areas for future research based on current gaps in knowledge.     

Th17 involvement in nonalcoholic fatty liver disease progression to non-alcoholic steatohepatitis

The nonalcoholic fatty liver disease(NAFLD) is the hepatic manifestation of the metabolic syndrome. NAFLD encompasses a wide histological spectrum ranging from benign simple steatosis to non-alcoholic steatohepatitis(NASH). Sustained inflammation in the liver is critical in this process. Hepatic macrophages, including liver resident macropaghes(Kupffer cells), monocytes infiltrating the injured liver, as well as specific lymphocytes subsets play a pivotal role in the initiation and perpetuation of the inflammatory response, with a major deleterious impact on the progression of fatty liver to fibrosis. During the last years, Th17 cells have been involved in the development of inflammation not only in liver but also in other organs, such as adipose tissue or lung. Differentiation of a na?ve T cell into a Th17 cell leads to pro-inflammatory cytokine and chemokine production with subsequent myeloid cell recruitment to the inflamed tissue. Th17 response can be mitigated by T regulatory cells that secrete anti-inflammatory cytokines. Both T cell subsets need TGF-β for their differentiation and a characteristic plasticity in their phenotype may render them new therapeutic targets. In this review, we discuss the role of the Th17 pathway in NAFLD progression to NASH and to liver fibrosis analyzing different animal models of liver injury and human studies.     

Nonalcoholic fatty liver disease as a multi-systemic disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. NAFLD includes a wide spectrum of liver conditions ranging from simple steatosis to nonalcoholic steatohepatitis and advanced hepatic fibrosis. NAFLD has been recognized as a hepatic manifestation of metabolic syndrome linked with insulin resistance. NAFLD should be considered not only a liver specific disease but also an early mediator of systemic diseases. Therefore, NAFLD is usually associated with cardiovascular disease, chronic kidney disease, type 2 diabetes, obesity, and dyslipidemia. NAFLD is highly prevalent in the general population and is associated with increased cardiovascular morbidity and mortality. The underlying mechanisms and pathogenesis of NAFLD with regard to other medical disorders are not yet fully understood. This review focuses on pathogenesis of NAFLD and its relation with other systemic diseases.     

Focus on emerging drugs for the treatment of patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD)has become the most common liver disorder in Western countries and is increasingly being recognized in developing nations.Fatty liver disease encompasses a spectrum of hepatic pathology,ranging from simple steatosis to non-alcoholic steatohepatitis,cirrhosis,hepatocellular carcinoma and end-stage liver disease.Moreover,NAFLD is often associated with other metabolic conditions,such as diabetes mellitus type 2,dyslipidemia and visceral obesity.The most recent guidelines suggest the management and treatment of patients with NAFLD considering both the liver disease and the associated metabolic co-morbidities.Diet and physical exercise are considered the first line of treatment for patients with NAFLD,but their results on therapeutic efficacy are often contrasting.Behavior therapy is necessary most of the time to achieve a sufficient result.Pharmacological therapy includes a wide variety of classes of molecules with different therapeutic targets and,often,little evidence supporting the real efficacy.Despite the abundance of clinical trials,NAFLD therapy remains a challenge for the scientific community,and there are no licensed therapies for NAFLD.Urgently,new pharmacological approaches are needed.Here,we will focus on the challenges facing actual therapeutic strategies and the most recent investigated molecules.     

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.     

Therapies for non-alcoholic fatty liver disease: A 2022 update

The incidence of non-alcoholic fatty liver disease (NAFLD) is rapidly increasing and lifestyle interventions to treat this disease by addressing the underlying metabolic syndrome are often limited. Many pharmacological interventions are being studied to slow or even reverse NAFLD progression. This review for hepatologists aims to provide an updated understanding of the pathogenesis of NAFLD, current recommended therapies, and the most promising treatment options that are currently under development.     

Oxidative stress: New insights on the association of non-alcoholic fatty liver disease and atherosclerosis

Non-alcoholic fatty liver disease (NAFLD) represents the most common and emerging chronic liver disease worldwide. It includes a wide spectrum of liver diseases ranging from simple fatty liver to non-alcoholic steatohepatitis (NASH), which may progress to fibrosis and more severe liver complications such as cirrhosis, hepatocellular carcinoma and liver mortality. NAFLD is strongly associated with obesity, insulin resistance, hypertension, and dyslipidaemia, and is now regarded as the liver manifestation of the metabolic syndrome. The increased mortality of patients with NAFLD is primarily a result of cardiovascular disease and, to a lesser extent, to liver related diseases. Increased oxidative stress has been reported in both patients with NAFLD and patient with cardiovascular risk factors. Thus, oxidative stress represents a shared pathophysiological disorder between the two conditions. Several therapeutic strategies targeting oxidative stress reduction in patients with NAFLD have been proposed, with conflicting results. In particular, vitamin E supplementation has been suggested for the treatment of non-diabetic, non-cirrhotic adults with active NASH, although this recommendation is based only on the results of a single randomized controlled trial. Other antioxidant treatments suggested are resveratrol, silybin, L-carnitine and pentoxiphylline. No trial so far, has evaluated the cardiovascular effects of antioxidant treatment in patients with NAFLD. New, large-scale studies including as end-point also the assessment of the atherosclerosis markers are needed.     

Nonalcoholic fatty liver disease and hepatic cirrhosis: comparison with viral hepatitis-associated steatosis

Nonalcoholic fatty liver disease(NAFLD) including nonalcoholic steatohepatitis(NASH) is globally increasing and has become a world-wide health problem. Chronic infection with hepatitis B virus or hepatitis C virus(HCV) is associated with hepatic steatosis. Viral hepatitis-associated hepatic steatosis is often caused by metabolic syndrome including obesity,type 2 diabetes mellitus and/or dyslipidemia. It has been reported that HCV genotype 3 exerts direct metabolic effects that lead to hepatic steatosis. In this review,the differences between NAFLD/NASH and viral hepatitis-associated steatosis are discussed.     

Physical activity as a treatment of non-alcoholic fatty liver disease: A systematic review

AIM: To review the effectiveness of exercise as a therapy for nonalcoholic fatty liver disease (NAFLD) and potential benefits in treating insulin resistance and atherosclerosis.METHODS: Medline (EBSCOhost) and PubMed were searched for English-language randomized controlled trials and prospective cohort studies in human adults aged ≥ 18 which investigated the various effects of exercise alone, a combination of exercise and diet, or exercise and diet coupled with behavioral modification on NAFLD from 2010 to Feburary 2015.RESULTS: Eighteen of 2298 available studies were chosen for critical review, which included 6925 patients. Nine (50%) studies were randomized controlled trials. Five (27.8%) studies utilized biopsy to examine the effects of physical activity on hepatic histology. The most commonly employed imaging modality to determine change in hepatic steatosis was hydrogen-magnetic resonance spectroscopy. Only two studies examined the effects of low impact physical activity for patients with significant mobility limitations and one compared the efficacy of aerobic and resistance exercise. No studies examined the exact duration of exercise required for hepatic and metabolic improvement in NAFLD.CONCLUSION: While exercise improved hepatic steatosis and underlying metabolic abnormalities in NAFLD, more studies are needed to define the most beneficial form and duration of exercise treatment.     

Carotid lesions in outpatients with nonalcoholic fatty liver disease

AIM： To ascertain whether carotid lesions are more prevalent in outpatients with incidental findings of nonalcoholic fatty liver disease （NAFLD） at abdominal ultrasound （US）. METHODS： One hundred and fifty-four consecutive outpatients （age range 24-90 years, both sexes） referred by general practitioners for abdominal US, and drinking less than 20 g alcohol/day, underwent carotid US for an assessment of carotid intima-media thickness （c-IMT） and carotid plaque prevalence. Hepatic steatosis, visceral fat thickness and subcutaneous fat thickness were also assessed at ultrasonography. RESULTS： Higher c-IMT values were found in the presence of NAFLD （90 patients）, even after adjustment for indices of general and abdominal obesity and for the principal cardiovascular risk factors （0.84 ± 0.10 mm vs 0.71 ± 0.10 mm, P 〈 0.001）. The prevalence of carotid plaques was 57.8% in the patients with NAFLD vs 37.5% in the patients without this condition （P = 0.02）. The adjusted relative risk of having carotid plaques for patients with NAFLD was 1.85 （95% CI： 1.33-2.57, P 〈 0.001）.CONCLUSION： An incidental finding of hepatic steatosis may suggest the presence of silent carotid atherosclerotic lesions.