Activation of c-Jun N-terminal kinase (JNK) has been implicated as a mechanism in the development of steatohepatitis. This finding together with the reported role of JNK signaling in the development of obesity and insulin resistance, two components of the metabolic syndrome and predisposing factors for fatty liver disease, suggest that JNK may be a central mediator of the metabolic syndrome and an important therapeutic target in steatohepatitis. To define the isoform specific functions of JNK in steatohepatitis associated with obesity and insulin resistance, the effects of JNK1 or JNK2 ablation were determined in developing and established steatohepatitis induced by a high fat diet. High fat diet-fed jnk1 null mice failed to develop excessive weight gain, insulin resistance or steatohepatitis. In contrast, jnk2-/- mice fed a high fat diet were obese and insulin resistant similar to wild-type mice and had increased liver injury. In mice with established steatohepatitis, an antisense oligonucleotide knockdown of jnk1 decreased the amount of steatohepatitis in concert with a normalization of insulin sensitivity. Knockdown of jnk2 improved insulin sensitivity but had no effect on hepatic steatosis and markedly increased liver injury. A jnk2 knockdown increased hepatic expression of the pro-apoptotic Bcl-2 family members Bim and Bax and the increase in liver injury resulted in part from a Bim-dependent activation of the mitochondrial death pathway.
JNK1 and JNK2 both mediate insulin resistance in high fat diet-fed mice, but the JNK isoforms have distinct effects on steatohepatitis with JNK1 promoting steatosis and hepatitis and JNK2 inhibiting hepatocyte cell death by blocking the mitochondrial death pathway.
antisense oligonucleotides; Bim; high fat diet; metabolic syndrome; nonalcoholic fatty liver disease
Nonalcoholic fatty liver disease (NAFLD), defined by excessive lipid accumulation in the liver, is the hepatic manifestation of insulin resistance and the metabolic syndrome. Due to the epidemics of obesity, NAFLD is rapidly becoming the leading cause of altered liver enzymes in Western countries. NAFLD encompasses a wide spectrum of liver disease ranging from simple uncomplicated steatosis, to steatohepatitis, cirrhosis, and hepatocellular carcinoma. Diet may affect the development of NAFLD either by increasing risk or by providing protective factors. Therefore, it is important to investigate the role of foods and/or food bioactives on the metabolic processes involved in steatohepatitis for preventive strategies. It has been reported that anthocyanins (ACNs) decrease hepatic lipid accumulation and may counteract oxidative stress and hepatic inflammation, but their impact on NAFLD has yet to be fully determined. ACNs are water-soluble bioactive compounds of the polyphenol class present in many vegetable products. Here, we summarize the evidence evaluating the mechanisms of action of ACNs on hepatic lipid metabolism in different experimental setting: in vitro, in vivo, and in human trials. Finally, a working model depicting the possible mechanisms underpinning the beneficial effects of ACNs in NAFLD is proposed, based on the available literature.
Nonalcoholic steatohepatitis (NASH) is considered the hepatic manifestation of metabolic syndrome (MetS) among adults. Emerging data suggest that MetS may be associated with nonalcoholic fatty liver disease (NAFLD) in children as well. We sought to determine whether MetS or its component features are associated with specific histological features or severity of NAFLD.
Children and adolescents aged 6 – 17 years enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) with clinical data obtained within 6 months of liver biopsy were included. MetS was defined as the presence of three or more of the following features as determined by application of age-adjusted normative values: central obesity, dyslipidemia, impaired fasting glucose, and elevated blood pressure. Liver biopsies were evaluated by the Pathology Committee of the NASH CRN.
Two hundred fifty four children were included in the analysis, of whom 65 (26 %) met specified criteria for MetS. Among children with MetS, there is a higher proportion of females who were on average older in age and pubertal. The risk of MetS was greatest among those with severe steatosis (odds ratio (OR) = 2.58 for grade 3 vs. grade 1 steatosis, P = 0.001). The presence of hepatocellular ballooning was also significantly associated with MetS (OR = 2.10, P = 0.03). Those with advanced fibrosis (stage 3/4) had an OR for MetS of 3.21 (P = 0.04) vs. those without fibrosis (stage 0). Borderline zone 1 or definite NASH patterns compared with “ not NASH ” were strongly associated with MetS (OR = 4.44, P = 0.005 and OR = 4.07, P = 0.002, respectively). The mean NAFLD Activity Score (NAS) was greater among children with MetS vs. those without (4.8 ± 1.4 vs. 4.3 ± 1.4, P = 0.01). Central obesity was significantly associated with steatosis, fibrosis, hepatocellular ballooning, and NAFLD pattern. Insulin resistance was significantly associated with steatosis, fibrosis, hepatocellular ballooning, NAS, and NAFLD pattern.
MetS is common among children with NAFLD and is associated with severity of steatosis, hepatocellular ballooning, NAS, NAFLD pattern, and the presence of advanced fibrosis. Individual MetS features, particularly central obesity and insulin resistance, were also associated with severity of NAFLD. MetS features should be considered in children with NAFLD as individually and collectively they help identify children with more advanced disease.
Hepatic steatosis has been reported in human immunodeficiency virus (HIV)/hepatitis C virus (HCV) coinfection. However, the features of steatohepatitis, including cytologic ballooning and pericellular fibrosis, its risk factors, and the impact on disease severity in such patients are unknown. To assess this, we prospectively reviewed liver histology in consecutive coinfected patients to define the prevalence and severity of the features of steatohepatitis, its risk factors, and its impact on the severity of liver disease. A total of 222 subjects (74% male, mean age 45, 78% African American, 90% genotype 1) were studied. The mean body mass index (BMI) was 26, and 18% had a BMI >30. The prevalence of risk factors for steatosis were: diabetes (31%), hypertension (15%), dyslipidemia (8%), metabolic syndrome (9%), and alcohol abuse (21%). Steatosis was present in 23% and steatohepatitis was present in 17%. The steatosis was mild (5%–33%) in 19%, and moderate to severe (>33%) in 4%. Cytologic ballooning and pericellular fibrosis were present in 30% and 13%, respectively. The mean Ishak score was 6.9, and 33% had bridging fibrosis or cirrhosis. Both steatosis and cytologic ballooning were associated with BMI, metabolic syndrome, and insulin resistance, and presence of either was strongly associated with advanced fibrosis (P < 0.0001). By multiple logistic regressions, the following associations were identified: increased BMI, diabetes, and genotype 3 with steatosis; diabetes with cytologic ballooning; and longer duration of infection with steatohepatitis.
Steatosis and steatohepatitis are present in 23% and 30%, respectively, of patients with HIV/HCV coinfection, and both are associated with an increased risk of having advanced fibrosis. Although we did identify genotype 3, increased BMI, and diabetes as risk factors, we found no independent association with antiretroviral therapy.
Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver pathologies and is associated with obesity and the metabolic syndrome, which represents a range of fatty liver diseases associated with an increased risk of type 2 diabetes. Molecular mechanisms underlying how to make transition from simple fatty liver to nonalcoholic steatohepatitis (NASH) are not well understood. However, accumulating evidence indicates that deregulation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway in hepatocytes is a common molecular event associated with metabolic dysfunctions including obesity, metabolic syndrome, and the NAFLD. A tumor suppressor PTEN negatively regulates the PI3K/AKT pathways through its lipid phosphatase activity. Molecular studies in the NAFLD support a key role for PTEN in hepatic insulin sensitivity and the development of steatosis, steatohepatitis, and fibrosis. We review recent studies on the features of the PTEN and the PI3K/AKT pathway and discuss the protein functions in the signaling pathways involved in the NAFLD. The molecular mechanisms contributing to the diseases are the subject of considerable investigation, as a better understanding of the pathogenesis will lead to novel therapies for a condition.
Nonalcoholic fatty liver disease (NAFLD) has become the most prevalent liver disease in western society and is increasing in parallel with the worldwide epidemic of obesity. It exists in a simple form, steatosis, or a more complex and more dangerous form, steatohepatitis, and it is often but not always associated with the metabolic syndrome. NAFLD can progress to cirrhosis and hepatocellular carcinoma. It is responsible for the majority of cryptogenic cirrhosis cases. Increasingly, NAFLD and its more sinister form, steatohepatitis, have been linked to the increased incidence of cardiovascular disease (CVD) worldwide, independent of the metabolic syndrome. Death from CVD surpasses death from liver complications, but that is beginning to change as people are living longer with CVD. In this article, we will review nonalcoholic fatty liver disease and its epidemiology, prevalence, pathology, and link to CVD.
fatty liver disease; metabolic syndrome; cardiovascular disease; nonalcoholic fatty liver disease; nonalcoholic steatohepatitis
Nonalcoholic fatty liver disease (NAFLD) is hepatic steatosis associated with metabolic abnormalities such as overweight/central obesity, insulin resistance, type 2 diabetes (T2D), and dyslipidemia. NAFLD is becoming the most common liver disease in contemporary society, with the highest prevalence in those over 60 years. NAFLD pathology ranges from simple steatosis to a necroinflammatory fibrosing disorder called steatohepatitis (SH), the latter associated with high risk of developing cirrhosis, often occuring in the seventh to ninth decades of life. While the main health implications of NAFLD are increased risk of developing T2D, cardiovascular diseases, and common cancers, there is substantantially increased standardized mortality, and deaths from decompensated cirrhosis and hepatocellular carcinoma (HCC). Little is known about the interactive effects of ageing and NAFLD, with most studies focusing on the younger population. This paper summarises the epidemiology, pathogenesis, and clinical course of NAFLD, with particular attention to persons over age 60 years. An approach to the management of NASH and its complications in the elderly, will also be presented here.
AIM: To investigate the histologic features of the liver in nonalcoholic fatty liver disease (NAFLD) cases according to the presence of metabolic syndrome or its individual components.
METHODS: We enrolled 81 patients (40 male, 41 female) who were diagnosed with fatty liver by ultrasonographic scan and fulfilled the inclusion criteria. First anamnesis, anthropometric, clinical, laboratory and imaging features of all participants were recorded and then liver biopsy was performed after gaining consent from patients. Diagnosis of metabolic syndrome was dependent on patients having 3 or more out of 5 risk criteria defined by the WHO. Biopsy specimens were assessed according to Brunt et al’s classification.
RESULTS: Sixty-nine of the 81 patients had nonalcoholic steatohepatitis (NASH), 11 had simple fatty liver and 1 had cirrhosis according to histologic evaluation. Comparisons were made between two groups of NASH patients, those with and without metabolic syndrome. We did not detect statistically significant differences in liver histology between NASH patients with and without metabolic syndrome.
CONCLUSION: NASH can progress without metabolic risk factors or the presence of metabolic syndrome.
Liver histology; Fatty liver; Nonalcoholic steatohepatitis; Metabolic risk factors; Metabolic syndrome
Nonalcoholic fatty liver disease (NAFLD) and gallstone disease (GD) are both highly prevalent in the general population and associated with obesity and insulin resistance. We aimed to evaluate the prevalence of GD in a cross sectional study of NAFLD patients and to define whether the presence of GD is associated with diabetes and predicts more severe liver disease.
We merged databases of four Liver Units, comprising 524 consecutive biopsy-proven NAFLD (373 males) observed between January 2003 and June 2010. GD was diagnosed in 108 (20%), and 313 cases (60%) were classified by liver biopsy as nonalcoholic steatohepatitis (NASH). The GD subgroup was characterized by a significantly higher prevalence of females, prediabetes/diabetes, abdominal obesity and metabolic syndrome, older age, higher BMI, fasting glucose, HOMA-IR and lower ALT. The prevalence of GD progressively increased with advancing fibrosis and with the severity of necroinflammatory activity (p for trend = 0.0001 and = 0.01, respectively), without differences in the severity of steatosis. At multivariate analysis GD was associated with female gender (OR 1.37, 95% CI 1.04–1.8), age (OR 1.027, 95% CI1.003–1.05), fasting glucose (OR 1.21, 95% CI 1.10–1.33) and NASH (OR 1.40,95% CI 1.06–1.89), whereas ALT levels were associated with a lower GD risk (OR 0.98, 95% CI 0.97–0.99). When subjects with cirrhosis were excluded from analysis, the association between GD and fasting glucose, female gender, and NASH was maintained.
Patients with NAFLD have a high prevalence of GD, which characterizes subjects with altered glucose regulation and more advanced liver disease.
In this prospective cohort study, we estimated the risk of developing more than 1 metabolic risk factor, using different obesity indices. In addition, we investigated the relative usefulness of the obesity indices for predicting development of such risk factors and calculated optimal cutoffs for the obesity indices.
The cohort comprised 10 038 representative residents of a small city and a rural county who were recruited in 2001–2002. Follow-up examinations were conducted every 2 years. Among the 3857 participants without metabolic syndrome at baseline, 1102 new cases occurred during the 6-year follow-up. Receiver operating characteristic (ROC) curves for the obesity indices were plotted to compare the usefulness of the obesity indices.
The numbers of new cases of multiple metabolic risk factors among people in the highest quintiles of body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR), and waist-height ratio at the baseline examination were 2 to 3 times those in the lowest quintiles. The area under the ROC curve for WHR was significantly higher than that for BMI. The optimal BMI cutoff was 24 kg/m2 in men and women, and the optimal WC cutoffs were 80 cm and 78 cm in men and women, respectively.
Both overall obesity and central obesity predicted risk of developing multiple metabolic risk factors, and WHR appeared to be a better discriminator than BMI. To prevent development of metabolic diseases among Koreans, it might be useful to lower the cutoff for abdominal obesity, as defined by WC.
obesity; metabolic risk factors; cohort; Korean
The most common finding related to nonalcoholic steatohepatitis is obesity, but a status of severe malnutrition can also induce the steatohepatitis. The authors report a rare case of steatohepatitis leading to hepatic decompensation caused by malnutrition after pancreaticoduodenectomy. A 68-year-old female patient who had been previously diagnosed with pancreatic cancer and had undergone pancreaticoduodenectomy 5 months previously presented with abdominal distension. Routine CT performed 3 months after the surgery revealed severe fatty liver without evidence of tumor recurrence. After undergoing pancreaticoduodenectomy her food intake had reduced, and as a result she had lost 7 kg of body weight over 2 months. At this admission, CT revealed moderate amounts of ascites without tumor recurrence. Furthermore, her albumin and lipid profile levels were markedly decreased, and she had a flapping tremor and slurred speech suggestive of hepatic encephalopathy. Her liver biopsy findings were consistent with steatohepatitis and disclosed macrovesicular steatosis without definite fibrosis. After careful nutritional control, her symptoms disappeared and her laboratory findings improved.
Nonalcoholic steatohepatitis; Malnutrition; Pancreaticoduodenectomy; Pancreatic cancer; Hepatic decompensation
Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of
clinicopathologic conditions ranging from steatosis alone to
nonalcoholic steatohepatitis (NASH), with varying risks for
progression to cirrhosis and hepatocellular carcinoma. There is
mounting evidence that NAFLD not only complicates obesity, but also
perpetuates its metabolic consequences. Critical event that leads to
progressive liver injury in NAFLD is unknown. Obesity reflects a
generalized proinflammatory state with its increased inflammatory
markers like C reactive protein, IL-6, IL-8, IL-10, PAI-1,
TNF-α, and hepatocyte growth factor. The elevated production of
these adipokines is increasingly considered to be important in the
development of diseases linked to obesity and the metabolic syndrome.
Disordered cytokine production is likely to play a role in the
pathogenesis of NAFLD. There is no effective treatment for NAFLD,
though weight loss may halt disease progression and revert
histological changes, the underlying mechanism remaining elusive.
All stages of the disease pathway from prevention, early
identification/diagnosis, and treatment require an understanding of
the pathogenesis of liver injury in NAFLD.
The prevalence of the metabolic syndrome with attendant morbid obesity continues to increase nationwide. A concomitant increase in non-alcoholic steatohepatitis (NASH) and associated end-stage liver disease requiring transplantation is expected to parallel this trend. Between January 1, 1997 and December 31, 2008, our center performed 813 solitary adult deceased-donor liver transplants. Patients were divided into groups based on the World Health Organization International Classification of obesity. Patients within each obesity class were compared to normal weight recipients. Pre-operative demographics among all groups were similar. NASH was more common in higher BMI groups. Operative time, blood product usage, ICU length of stay, infectious complications, and biliary complications requiring intervention were all higher in obese recipients. Deep venous thrombosis occurred more commonly in patients with Class III obesity. Patients with Class II obesity had lower patient (HR 1.82, CI 1.09–3.01, p=0.02) and allograft survival (HR 1.62, CI 1.02–2.65, p=0.04). Obesity class did not reach statistical significance on multivariate analysis. Despite increased technical operative challenges and medical complexities associated with increasing recipient BMI, morbid obesity in and of itself should not be an absolute contraindication to liver transplantation as these patients have reasonable long-term outcomes.
body-mass index; non-alcoholic steatohepatitis
The worldwide epidemic of obesity and the metabolic syndrome has made nonalcoholic fatty liver disease (NAFLD), one of the most important liver diseases of our time. NAFLD is now the commonest cause of abnormal liver test results in industrialized countries and its incidence is rising. The current treatment of nonalcoholic steatohepatitis (NASH) has focused on lifestyle modification to achieve weight loss and modification of risk factors, such as insulin resistance, dyslipidemia, and hyperglycemia associated with the metabolic syndrome. With our increasing understanding of the pathogenesis of NASH, have come a plethora of new pharmacologic options with great potential to modify the natural history of NAFLD and NASH. This article focuses on a number of novel molecular targets for the treatment of NASH as well as the evidence for currently available therapy. It should be noted, however, that in part because of the long natural history of NASH and NAFLD, no therapy to date has been shown to unequivocally alter liver-related morbidity and mortality in these patients.
Peroxisome proliferator-activated receptors; Cannabinoid system; Incretins; Adiponectin; Leptin; Metabolic liver disease; Angiotensin receptor blockers
DNA damage is present in both genomic and mitochondrial DNA in atherosclerosis. However, whether DNA damage itself promotes atherosclerosis, or is simply a byproduct of the risk factors that promote atherosclerosis, is unknown.
To examine the effect of DNA damage on atherosclerosis, we studied apolipoprotein (Apo)E−/− mice that were haploinsufficient for the protein kinase ATM (ataxia telangiectasia mutated), which coordinates DNA repair.
Methods and Results
ATM+/−/ApoE−/− mice developed accelerated atherosclerosis and multiple features of the metabolic syndrome, including hypertension, hypercholesterolemia, obesity, steatohepatitis, and glucose intolerance. Transplantation with ATM+/+ bone marrow attenuated atherosclerosis but not the metabolic syndrome. ATM+/− smooth muscle cells and macrophages showed increased nuclear DNA damage and defective DNA repair signaling, growth arrest, and apoptosis. Metabolomic screening of ATM+/−/ApoE−/− mouse tissues identified metabolic changes compatible with mitochondrial defects, with increased β-hydroxybutyrate but reduced lactate, reduced glucose, and alterations in multiple lipid species. ATM+/−/ApoE−/− mouse tissues showed an increased frequency of a mouse mitochondrial “common” deletion equivalent and reduced mitochondrial oxidative phosphorylation.
We propose that failure of DNA repair generates defects in cell proliferation, apoptosis, and mitochondrial dysfunction. This in turn leads to ketosis, hyperlipidemia, and increased fat storage, promoting atherosclerosis and the metabolic syndrome. Prevention of mitochondrial dysfunction may represent a novel target in cardiovascular disease.
atherosclerosis; mitochondria; DNA damage; metabolic syndrome
Intrauterine growth retardation (IUGR), the most important cause of perinatal mortality and morbidity, is defined as a foetal growth less than normal for the population, often used as synonym of small for gestational age (SGA). Studies demonstrated the relationships between metabolic syndrome (MS) and birthweight. This study suggested that, in children, adolescents, and adults born SGA, insulin resistance could lead to other metabolic disorders: type 2 diabetes (DM2), dyslipidemia, and nonalcoholic fatty liver disease (NAFLD). NAFLD may evolve to nonalcoholic steatohepatitis (NASH), and it is related to the development of MS. Lifestyle intervention, physical activity, and weight reduction represent the mainstay of NAFLD therapy. In particular, a catch-up growth reduction could decrease the risk to develop MS and NAFLD.
In this paper, we outline clinical and experimental evidences of the association between IUGR, metabolic syndrome, insulin resistance, and NAFLD and discuss on a possible management to avoid the risk of MS in adulthood.
Rodent models of fatty liver disease are essential research tools that provide a window into disease pathogenesis and a testing ground for prevention and treatment. Models come in many varieties involving dietary and genetic manipulations, and sometimes both. High-energy diets that induce obesity do not uniformly cause fatty liver disease; this has prompted close scrutiny of specific macronutrients and nutrient combinations to determine which have the greatest potential for hepatotoxicity. At the same time, diets that do not cause obesity or the metabolic syndrome but do cause severe steatohepatitis have been exploited to study factors important to progressive liver injury, including cell death, oxidative stress, and immune activation. Rodents with a genetic predisposition to overeating offer yet another model in which to explore the evolution of fatty liver disease. In some animals that overeat, steatohepatitis can develop even without resorting to a high-energy diet. Importantly, these models and others have been used to document that aerobic exercise can prevent or reduce fatty liver disease. This review focuses primarily on lessons learned about steatohepatitis from manipulations of diet and eating behavior. Numerous additional insights about hepatic lipid metabolism, which have been gained from genetically engineered mice, are also mentioned. Antioxid. Redox Signal. 15, 535–550.
Endocrinologists are encountering patients with obesity-related complications such as metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM) on a daily basis. Nonalcoholic fatty liver disease (NAFLD) is a liver condition characterized by insulin resistance, hepatic steatosis and frequently T2DM. This is now the most common chronic liver condition in adults and is present in the majority of obese subjects. Liver fat accumulation may range from simple steatosis to severe steatohepatitis with hepatocyte necroinflammation (or nonalcoholic steatohepatitis [NASH]). Although the natural history is incompletely understood, NAFLD may lead to serious medical consequences ranging from cirrhosis and hepatocellular carcinoma to earlier onset of T2DM and cardiovascular disease (CVD). The diagnosis of NAFLD may be challenging because signs and symptoms are frequently absent or nonspecific, and thus easily missed. Liver aminotransferases may be helpful if elevated, but most times are normal in the presence of the disease. Liver imaging may assist in the diagnosis (ultrasound or MRI and spectroscopy) but a definitive diagnosis of NASH still requires a liver biopsy. This may change in the near future as novel biomarkers become available. Treatment of NAFLD includes aggressive management of associated cardiovascular risk factors and many times control of T2DM. Pioglitazone and vitamin E appear promising for patients with NASH, although long-term studies are unavailable. In summary, this review hopes to address the common clinical dilemmas that endocrinologists face in the diagnosis and management of NAFLD and increase awareness of a potentially serious medical condition.
diabetes; fatty liver; insulin resistance; nonalcoholic fatty liver disease (NAFLD); nonalcoholic steatohepatitis (NASH)
Obesity has been linked with a chronic state of inflammation which may be involved in the development of metabolic syndrome, cardiovascular disease, non-alcoholic steatohepatitis, and even cancer. The objective of this study was to examine the association between obesity class and levels of inflammatory biomarkers from men and women who participated in the 1999–2004 National Health and Nutrition Examination Survey (NHANES).
Serum concentrations of C-reactive protein (CRP) and fibrinogen were measured among US participants of the 1999–2004 NHANES. We examined biomarker levels across different weight classes with normal weight, overweight, and obesity classes 1, 2, and 3 were defined as BMI of <25.0, 25.0–29.9, 30.0–34.9, 35.0–39.9, and ≥40.0, respectively.
With CRP levels for normal weight individuals as a reference, CRP levels nearly doubled with each increase in weight class: +0.11 mg/dl (95% CI, 0.06–0.16) for overweight, +0.21 mg/dl (95% CI, 0.16–0.27) for obesity class 1, +0.43 mg/dl (95% CI, 0.26–0.61) for obesity class 2, and +0.73 mg/dl (95% CI, 0.55–0.90) for obesity class 3. With normal weight individuals as a reference, fibrinogen levels increase with increasing weight class and were highest for obesity class 3 individuals, +93.5 mg/dl (95% CI, 72.9–114.1). Individuals with hypertension or diabetes have higher levels of CRP and fibrinogen levels compared to individuals without hypertension or diabetes, even when stratified according to BMI.
There is a direct association between increasing obesity class and the presence of obesity-related comorbidities such as diabetes and hypertension with high levels of inflammatory biomarkers.
Inflammation; C-reactive protein; Fibrinogen; Obesity; Biomarker; Hypertension; Diabetes; NHANES
Nonalcoholic fatty liver disease (NAFLD) affects one-fifth of the adult population and is currently the commonest liver problem in the western world. The prevalence of NAFLD is likely to rise over the coming decades in parallel to the obesity and diabetes epidemics. A retrospective study was undertaken in a UK. district general hospital (DGH) to determine the clinical and laboratory features of patients with NAFLD.
Methods and findings
A total of 48 patients with NAFLD were identified. Most (54%) were asymptomatic on presentation and 90% had an echogenic liver on ultrasonography (USS). Liver tests were elevated in the majority, but did not distinguish between simple steatosis and steatohepatitis. Having features of the metabolic syndrome and a low platelet count (P = 0.028) may help identify patients with advanced hepatic fibrosis.
NAFLD is common in the DGH and should be considered in all patients with metabolic risk factors. A liver biopsy should be considered in those with low platelets, type II diabetes mellitus, and the metabolic syndrome.
District general hospital; Liver tests; Metabolic syndrome; Nonalcoholic fatty liver; Ultrasonography
Hepatitis C virus (HCV) infection is an important risk factor for insulin resistance (IR). The latter is the pathogenic foundation underlying metabolic syndrome, steatosis and cirrhosis, and possibly hepatocellular carcinoma (HCC). The interplay between genetic and environmental risk factors ultimately leads to the development of IR. Obesity is considered a major risk factor, with dysregulation of levels of secreted adipokines from distended adipose tissue playing a major role in IR. HCV-induced IR may be due to the HCV core protein inducing proteasomal degradation of insulin receptor substrates 1 and 2, blocking intracellular insulin signaling. The latter is mediated by increased levels of both tumour necrosis factor-α (TNF-α) and suppressor of cytokine signaling 3 (SOC-3). IR, through different mechanisms, plays a role in the development of steatosis and its progression to steatohepatitis, cirrhosis and even HCC. In addition, IR has a role in impairing TNF signaling cascade, which in turn blocks STAT-1 translocation and interferon stimulated genes production avoiding the antiviral effect of interferon.
Hepatitis C virus-chronic hepatitis C; Insulin resistance; Sustained virological response; Homeostasis model assessment
The endemic occurrence of obesity and the associated risk factors that constitute the metabolic syndrome have been predicted to lead to a dramatic increase in chronic liver disease. Non-alcoholic steatohepatitis (NASH) has become the most frequent liver disease in countries with a high prevalence of obesity. In addition, hepatic steatosis and insulin resistance have been implicated in disease progression of other liver diseases, including chronic viral hepatitis and hepatocellular carcinoma. The molecular mechanisms underlying the link between insulin signaling and hepatocellular injury are only partly understood. We have explored the role of the antiapoptotic caspase-8 homolog cellular FLICE-inhibitory protein (cFLIP) on liver cell survival in a diabetic model with hypoinsulinemic diabetes in order to delineate the role of insulin signaling on hepatocellular survival. cFLIP regulates cellular injury from apoptosis signaling pathways, and loss of cFLIP was previously shown to promote injury from activated TNF and CD95/Apo-1 receptors. In mice lacking cFLIP in hepatocytes (flip−/−), loss of insulin following streptozotocin treatment resulted in caspase- and c-Jun N-terminal kinase (JNK)-dependent liver injury after 21 days. Substitution of insulin, inhibition of JNK using the SP600125 compound in vivo or genetic deletion of the mitogen-activated protein kinase (MAPK)9 (JNK2) in all tissues abolished the injurious effect. Strikingly, the difference in injury between wild-type and cFLIP-deficient mice occurred only in vivo and was accompanied by liver-infiltrating inflammatory cells with a trend toward increased amounts of NK1.1-positive cells and secretion of proinflammatory cytokines. Transfer of bone marrow from rag-1-deficient mice that are depleted from B and T lymphocytes prevented liver injury in flip−/− mice. These findings support a direct role of insulin on cellular survival by alternating the activation of injurious MAPK, caspases and the recruitment of inflammatory cells to the liver. Thus, increasing resistance to insulin signaling pathways in hepatocytes appears to be an important factor in the initiation and progression of chronic liver disease.
apoptosis; liver injury; JNK2; hyperglycemia; cFLIP
AIM: To evaluate insulin resistance, cytolysis and non-alcoholic steatohepatitis (NASH) score (NAS) using the Kleiner and Brunt criteria in 54 patients with NASH and mild-to-moderate hypertension, treated with telmisartan vs valsartan for 20 mo.
METHODS: All patients met the NCEP-ATP III criteria for metabolic syndrome. Histology confirmed steatohepatitis, defined as a NAS greater than five up to 3 wk prior inclusion, using the current criteria. Patients with viral hepatitis, chronic alcohol intake, drug abuse or other significant immune or metabolic hepatic pathology were excluded. Subjects were randomly assigned either to the valsartan (V) group (standard dose 80 mg o.d., n = 26), or to the telmisartan (T) group (standard dose 20 mg o.d., n = 28). Treatment had to be taken daily at the same hour with no concomitant medication or alcohol consumption allowed. Neither the patient nor the medical staff was aware of treatment group allocation. Paired liver biopsies obtained at inclusion (visit 1) and end of treatment (EOT) were assessed by a single blinded pathologist, not aware of patient or treatment group. Blood pressure, BMI, ALT, AST, HOMA-IR, plasma triglycerides (TG) and total cholesterol (TC) were evaluated at inclusion and every 4 mo until EOT (visit 6).
RESULTS: At EOT we noticed a significant decrease in ALT levels vs inclusion in all patients and this decrease did not differ significantly in group T vs group V. HOMA-IR significantly decreased at EOT vs inclusion in all patients but in group T, the mean HOMA-IR decrease per month was higher than in group V. NAS significantly diminished at EOT in all patients with a higher decrease in group T vs group V.
CONCLUSION: Angiotensin receptor blockers seem to be efficient in hypertension-associated NASH. Telmisartan showed a higher efficacy regarding insulin resistance and histology, perhaps because of its specific PPAR-gamma ligand effect.
Telmisartan; Valsartan; Non-alcoholic steatohepatitis; Hypertension; Insulin-resistance; Hepatic steatosis; Necroinflammation
While non-alcoholic fatty liver disease (NAFLD) is highly prevalent (15% to 45%) in modern societies, only 10% to 25% of cases develop hepatic fibrosis leading to cirrhosis, end-stage liver disease or hepatocellular carcinoma. Apart from pre-existing fibrosis, the strongest predictor of fibrotic progression in NAFLD is steatohepatitis or non-alcoholic steatohepatitis (NASH). The critical features other than steatosis are hepatocellular degeneration (ballooning, Mallory hyaline) and mixed inflammatory cell infiltration. While much is understood about the relationship of steatosis to metabolic factors (over-nutrition, insulin resistance, hyperglycemia, metabolic syndrome, hypoadiponectinemia), less is known about inflammatory recruitment, despite its importance for the perpetuation of liver injury and fibrogenesis. In this review, we present evidence that liver inflammation has prognostic significance in NAFLD. We then consider the origins and components of liver inflammation in NASH. Hepatocytes injured by toxic lipid molecules (lipotoxicity) play a central role in the recruitment of innate immunity involving Toll-like receptors (TLRs), Kupffer cells (KCs), lymphocytes and neutrophils and possibly inflammasome. The key pro-inflammatory signaling pathways in NASH are nuclear factor-kappa B (NF-κB) and c-Jun N-terminal kinase (JNK). The downstream effectors include adhesion molecules, chemokines, cytokines and the activation of cell death pathways leading to apoptosis. The upstream activators of NF-κB and JNK are more contentious and may depend on the experimental model used. TLRs are strong contenders. It remains possible that inflammation in NASH originates outside the liver and in the gut microbiota that prime KC/TLR responses, inflamed adipose tissue and circulating inflammatory cells. We briefly review these mechanistic considerations and project their implications for the effective treatment of NASH.
Non-alcoholic fatty liver disease; Hepatic fibrosis; Non-alcoholic steatohepatitis
The pathological mechanisms that distinguish simple steatosis from steatohepatitis (or NASH, with consequent risk of cirrhosis and hepatocellular cancer) remain incompletely defined. Whereas both a methionine- and choline-deficient diet (MCDD) and a choline-deficient diet (CDD) lead to hepatic triglyceride accumulation, MCDD alone is associated with hepatic insulin resistance and inflammation (steatohepatitis). We used metabolic tracer techniques, including stable isotope ([13C4]palmitate) dilution and mass isotopomer distribution analysis (MIDA) of [13C2]acetate, to define differences in intrahepatic fatty acid metabolism that could explain the contrasting effect of MCDD and CDD on NASH in C57Bl6 mice. Compared with control-supplemented (CS) diet, liver triglyceride pool sizes were similarly elevated in CDD and MCDD groups (24.37 ± 2.4, 45.94 ± 3.9, and 43.30 ± 3.5 μmol/liver for CS, CDD, and MCDD, respectively), but intrahepatic neutrophil infiltration and plasma alanine aminotransferase (31 ± 3, 48 ± 4, 231 ± 79 U/l, P < 0.05) were elevated only in MCDD mice. However, despite loss of peripheral fat in MCDD mice, neither the rate of appearance of palmitate (27.2 ± 3.5, 26.3 ± 2.3, and 28.3 ± 3.5 μmol·kg−1·min−1) nor the contribution of circulating fatty acids to the liver triglyceride pool differed between groups. Unlike CDD, MCDD had a defect in hepatic triglyceride export that was confirmed using intravenous tyloxapol (142 ± 21, 122 ± 15, and 80 ± 7 mg·kg−1·h−1, P < 0.05). Moreover, hepatic de novo lipogenesis was significantly elevated in the MCDD group only (1.4 ± 0.3, 2.3 ± 0.4, and 3.4 ± 0.4 μmol/day, P < 0.01). These findings suggest that important alterations in hepatic fatty acid metabolism may promote the development of steatohepatitis. Similar mechanisms may predispose to hepatocyte damage in human NASH.
nonalcoholic fatty liver disease; steatohepatitis; free fatty acids; de novo lipogenesis; methionine- and choline-deficient diet; choline-deficient diet