The European NAFLD Registry: A real-world longitudinal cohort study of nonalcoholic fatty liver disease.

Non-Alcoholic Fatty Liver Disease (NAFLD), a progressive liver disease that is closely associated with obesity, type 2 diabetes, hypertension and dyslipidaemia, represents an increasing global public health challenge. There is significant variability in the disease course: the majority exhibit only fat accumulation in the liver but a significant minority develop a necroinflammatory form of the disease (non-alcoholic steatohepatitis, NASH) that may progress to cirrhosis and hepatocellular carcinoma. At present our understanding of pathogenesis, disease natural history and long-term outcomes remain incomplete. There is a need for large, well characterised patient cohorts that may be used to address these knowledge gaps and to support the development of better biomarkers and novel therapies. The European NAFLD Registry is an international, prospectively recruited observational cohort study that aims to establish a large, highly-phenotyped patient cohort and linked bioresource. Here we describe the infrastructure, data management and monitoring plans, and the standard operating procedures implemented to ensure the timely and systematic collection of high-quality data and samples. Already recruiting subjects at secondary/tertiary care centres across Europe, the Registry is supporting the European Union IMI2-funded LITMUS 'Liver Investigation: Testing Marker Utility in Steatohepatitis' consortium, which is a major international effort to robustly validate biomarkers that diagnose, risk stratify and/or monitor NAFLD progression and liver fibrosis stage. The European NAFLD Registry has the demonstrable capacity to support research and biomarker development at scale and pace.

Transcriptional regulation of PNPLA3 and its impact on susceptibility to nonalcoholic fatty liver Disease (NAFLD) in humans.

The increased expression of PNPLA3148M leads to hepatosteatosis in mice. This study aims to investigate the genetic control of hepatic PNPLA3 transcription and to explore its impact on NAFLD risk in humans. Through a locus-wide expression quantitative trait loci (eQTL) mapping in two human liver sample sets, a PNPLA3 intronic SNP, rs139051 A>G was identified as a significant eQTL (p = 6.6×10-8) influencing PNPLA3 transcription, with the A allele significantly associated with increased PNPLA3 mRNA. An electrophoresis mobility shift assay further demonstrated that the A allele has enhanced affinity to nuclear proteins than the G allele. The impact of this eQTL on NAFLD risk was further tested in three independent populations. We found that rs139051 did not independently affect the NAFLD risk, whilst rs738409 did not significantly modulate PNPLA3 transcription but was associated with NAFLD risk. The A-G haplotype associated with higher transcription of the disease-risk rs738409 G allele conferred similar risk for NAFLD compared to the G-G haplotype that possesses a lower transcription level. Our study suggests that the pathogenic role of PNPLA3148M in NAFLD is independent of the gene transcription in humans, which may be attributed to the high endogenous transcription level of PNPLA3 gene in human livers.

A common polymorphism in the ABCB11 gene is associated with advanced fibrosis in hepatitis C but not in non-alcoholic fatty liver disease.

Chronic HCV (hepatitis C virus)-associated cirrhosis represents a major indication for liver transplantation. Bile acids contribute to hepatic stellate cell activation as a key event in fibrogenesis. The aim of the present study was to investigate the role of bile acids and polymorphisms in bile acid level-regulating genes on fibrosis progression. A total of 206 subjects with chronic HCV infection were included for ABCB11 (ATP-binding cassette, subfamily B, member II) 1331T>C and NR1H4 (nuclear receptor) -1G>T genotyping, 178 of which were analysed for fibrosis stage. Exclusion criteria were HBV (hepatitis B virus) or HIV coinfection, alcohol >40 g/day and morbid obesity. A total of 358 patients with NAFLD (non-alcoholic fatty liver disease) were genotyped for comparison with a non-viral liver disease. Caucasian individuals (n = 110), undergoing liver resection for focal hepatic metastasis, served as controls. The ABCB11 1331C allele was significantly overrepresented in HCV patients compared with controls {allelic frequency 62.9%; OR (odds ratio), 1.41 [95% CI (confidence interval), 1.012-1.965]}. Median plasma bile acid levels were not significantly increased in the CC compared with TT genotype [7.2 (1-110) µmol/l compared with 3.5 (1-61) µmol/l; values are medians (range). A significant association between the presence of cirrhosis and ABCB11 genotype (CC compared with CT or TT, P=0.047) was observed in the χ2 test and independent of other risk factors of age, gender, body mass index and disease duration in multivariate analysis (P = 0.010). No such association could be observed in fatty liver patients with regard to advanced fibrosis (F ≥ 2). The common ABCB11 1331CC genotype, which is present in 40% of HCV patients and renders the carrier susceptible to increased bile acid levels, is associated with cirrhosis.

Theophylline improves steroid sensitivity in acute alcoholic hepatitis.

UNLABELLED: Corticosteroid therapy has shown some benefit in severe acute alcoholic hepatitis (AAH); however, this is limited by uncertainty in patient selection and variable clinical response. Theophylline has been shown to ameliorate impaired steroid sensitivity in chronic obstructive pulmonary disease by facilitating corticosteroid-induced silencing of proinflammatory genes. We aimed to explore the mechanistic basis of the variable response to corticosteroid therapy seen in patients with AAH and to address the extent to which theophylline can improve this response. The ability of dexamethasone to inhibit phytohemagglutinin-induced lymphocyte proliferation was assessed by (3)H-thymidine incorporation in 12 severe AAH patients and age-matched and sex-matched controls. Steroid sensitivity was measured in terms of I(max), the maximum inhibition of proliferation. The effect of 10(-5) M theophylline and, in survivors, change in I(max) during recovery were observed. Lymphocyte steroid sensitivity was found to be significantly reduced in AAH compared with controls (I(max) 67[+/-4.5]% versus 95[+/-2.3]%, P = 0.0002) and correlated with clinical markers of steroid responsiveness. In survivors, I(max) increased in recovery. Theophylline 10(-5) M significantly increased lymphocyte steroid sensitivity (I(max) 86[+/-6.6]% versus 67[+/-5.0]%, P = 0.027). CONCLUSION: Acute alcoholic hepatitis is associated with significant lymphocyte steroid insensitivity, which improves in recovery and can be ameliorated ex vivo by theophylline. This offers potential to rationalize corticosteroid prescribing in AAH and, furthermore, justifies investigation of this novel role for an existing pharmacological agent in this common and frequently fatal condition.

Disorders of coagulation and hemostasis in abdominal obesity: emerging role of fatty liver.

Abdominal obesity represents a public health concern because its prevalence is reaching epidemic proportions worldwide, and it is associated with an increased risk of cardiovascular morbidity and mortality and other pathological conditions. A large body of evidence suggests that abdominal obesity is associated with a prothrombotic tendency, which may, at least in part, contribute to the increased risk of atherothrombosis in these individuals. This review briefly summarizes the evidence of direct and indirect effects of the accumulation of excess lipid in visceral adipose tissue on coagulation and fibrinolysis. In addition, this article critically appraises the rapidly expanding body of experimental and clinical data that support a potential direct contribution for the accumulation of excess lipid in the liver (i.e., nonalcoholic fatty liver disease, a very frequent pathological condition in subjects with abdominal obesity) in the pathogenesis of the obesity-induced disorders of coagulation and fibrinolysis.

Acetate, the key modulator of inflammatory responses in acute alcoholic hepatitis.

UNLABELLED: Acute alcoholic hepatitis is characterized by disproportionate macrophage inflammatory cytokine responses to bacterial lipopolysaccharide. Lack of knowledge of the underlying mechanism has limited progress toward effective therapy. We postulated a novel mechanism by which ethanol increases histone acetylation, increasing proinflammatory gene transcription and cytokine synthesis. Cytokine responses to lipopolysaccharide in a human macrophage cell line cultured in 86 mM ethanol, 1 mM acetate, and normal media were measured by multiplex immunoassay. Changes in histone acetylation were determined by immunofluorescence microscopy and chromatin immunoprecipitation on presentation. The effect of ethanol and acetate on acetyl-coenzyme A (acetyl-coA) synthetases, which convert acetate to acetyl-coA, the substrate for histone acetylation, was determined by quantitative reverse-transcription polymerase chain reaction and immunoblotting. Knockdown of acetyl-coA synthetases by short hairpin RNA (shRNA) was used to determine their role in ethanol's enhancement of the inflammatory cytokine response. Ethanol-exposed macrophages developed enhanced interleukin 6 (IL6), IL8, and tumor necrosis factor alpha responses to lipopolysaccharide with time-dependent increases in histone acetylation that could be prevented by inhibition of ethanol metabolism. Chromatin immunoprecipitation confirmed increased histone acetylation at promoter regions of specific cytokine genes. The effect of ethanol was reproduced by incubation with acetate, the principal hepatic metabolite of ethanol, and both ethanol and acetate reduced histone deacetylase activity and up-regulated acetyl-coA synthetases. Knockdown of the acetyl-coA synthetases abrogated the effect of ethanol on cytokine production. CONCLUSION: Synthesis of metabolically available acetyl-coA from acetate is critical to the increased acetylation of proinflammatory gene histones and consequent enhancement of the inflammatory response in ethanol-exposed macrophages. This mechanism is a potential therapeutic target in acute alcoholic hepatitis.

Genetic association studies in drug-induced liver injury.

Genetic studies on drug-induced liver injury (DILI) have proved challenging, both because of their rarity and their difficulty in replicating observed effects. However, significant progress has now been achieved by both candidate-gene and genome-wide association studies. These two approaches are considered in detail, together with examples of DILI due to specific drugs where consistent associations have been reported. Particular consideration is given to associations between antituberculosis drug-related liver injury and the "slow acetylator" genotype for N-acetyltransferase 2, amoxicillin/clavulanate-related liver injury, and the human leukocyte antigen (HLA) class II DRB1*1501 allele and flucloxacillin-related injury and the HLA class I B*5701 allele. Although these associations are drug-specific, the possibility that additional, more general susceptibility genes for DILI exist requires further investigation, ideally by genome-wide association studies involving international collaboration. The possibility of interethnic variation in susceptibility to DILI also requires further study.

Increased intestinal permeability and tight junction alterations in nonalcoholic fatty liver disease.

UNLABELLED: The role played by the gut in nonalcoholic fatty liver disease (NAFLD) is still a matter of debate, although animal and human studies suggest that gut-derived endotoxin may be important. We investigated intestinal permeability in patients with NAFLD and evaluated the correlations between this phenomenon and the stage of the disease, the integrity of tight junctions within the small intestine, and prevalence of small intestinal bacterial overgrowth (SIBO). We examined 35 consecutive patients with biopsy-proven NAFLD, 27 with untreated celiac disease (as a model of intestinal hyperpermeability) and 24 healthy volunteers. We assessed the presence of SIBO by glucose breath testing (GBT), intestinal permeability by means of urinary excretion of (51)Cr-ethylene diamine tetraacetate ((51)Cr-EDTA) test, and the integrity of tight junctions within the gut by immunohistochemical analysis of zona occludens-1 (ZO-1) expression in duodenal biopsy specimens. Patients with NAFLD had significantly increased gut permeability (compared with healthy subjects; P < 0.001) and a higher prevalence of SIBO, although both were lower than in the untreated celiac patients. In patients with NAFLD, both gut permeability and the prevalence of SIBO correlated with the severity of steatosis but not with presence of NASH. CONCLUSIONS: Our results provide the first evidence that NAFLD in humans is associated with increased gut permeability and that this abnormality is related to the increased prevalence of SIBO in these patients. The increased permeability appears to be caused by disruption of intercellular tight junctions in the intestine, and it may play an important role in the pathogenesis of hepatic fat deposition.

Non-alcoholic fatty liver disease: current concepts and management strategies.

Non-alcoholic fatty liver disease (NAFLD), the liver manifestation of the metabolic syndrome, is now considered to be the commonest liver problem in the western world. This apparent 'epidemic', coupled with an accumulating body of evidence that a significant proportion of patients with NAFLD can progress to cirrhosis, liver failure and hepatocellular carcinoma (HCC), has--perhaps not surprisingly--led to an exponential growth in clinical and basic studies investigating all aspects of this hitherto largely ignored disease. The result is a vast increase in understanding of the natural history, clinical features and pathophysiology of NAFLD over the last five years which has now begun to inform the development of rational management strategies.

Valine-alanine manganese superoxide dismutase polymorphism is not associated with alcohol-induced oxidative stress or liver fibrosis.

The role of genetic factors in the pathogenesis of alcohol-induced liver disease (ALD) is receiving increasing attention. Recently, it has been reported that homozygosity for a valine to alanine substitution in the mitochondrial targeting sequence of manganese superoxide dismutase (Mn-SOD) represents a risk factor for severe ALD. Because this mutation is postulated to modify enzyme transport into mitochondria, we have sought confirmatory evidence of this association in a larger group of patients and investigated whether this polymorphism might influence alcohol-induced oxidative stress. Genotyping for the valine-alanine (Val-Ala) polymorphism of the Mn-SOD gene in 281 patients with advanced ALD (cirrhosis/fibrosis) and 218 drinkers without liver disease showed no differences in either the heterozygote (55% vs. 50%) or the homozygote (19% vs. 23%) frequency for the alanine allele. By measuring the titers of circulating antibodies against oxidized cardiolipin (OX-CL) and malondialdehyde (MDA) or hydroxy-ethyl radical (HER) adducts as markers of oxidative stress, we found a significant increase in ALD patients compared with healthy controls. However, the carriers of the alanine Mn-SOD allele had titers of anti-MDA, anti-HER, and anti-OX-CL IgG comparable with heterozygotes and patients homozygous for the valine allele. Similarly, the frequency of subjects with antibody titers above the 95th percentile of controls was not increased among homozygotes for the alanine Mn-SOD allele. In conclusion, in our population Val-Ala polymorphism in Mn-SOD influences neither susceptibility to alcohol-induced liver fibrosis nor alcohol-induced oxidative stress.