Jeremy Cobbold

Non-alcoholic fatty liver disease and diabetes

Non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2DM) are common conditions that regularly co-exist and can act synergistically to drive adverse outcomes. The presence of both NAFLD and T2DM increases the likelihood of the development of complications of diabetes (including both macro- and micro- vascular complications) as well as augmenting the risk of more severe NAFLD, including cirrhosis, hepatocellular carcinoma and death. The mainstay of NAFLD management is currently to reduce modifiable metabolic risk. Achieving good glycaemic control and optimising weight loss are pivotal to restricting disease progression. Once cirrhosis has developed, it is necessary to screen for complications and minimise the risk of hepatic decompensation. Therapeutic disease modifying options for patients with NAFLD are currently limited. When diabetes and NAFLD co-exist, there are published data that can help inform the clinician as to the most appropriate oral hypoglycaemic agent or injectable therapy that may improve NAFLD, however most of these data are drawn from observations in retrospective series and there is a paucity of well-designed randomised double blind placebo controlled studies with gold-standard end-points. Furthermore, given the heterogeneity of inclusion criteria and primary outcomes, as well as duration of follow-up, it is difficult to draw robust conclusions that are applicable across the entire spectrum of NAFLD and diabetes. In this review, we have summarised and critically evaluated the available data, with the aim of helping to inform the reader as to the most pertinent issues when managing patients with co-existent NAFLD and T2DM.

Raised hepatic bile acid concentrations during pregnancy in mice are associated with reduced farnesoid X receptor function.

Pregnancy alters bile acid homeostasis and can unmask cholestatic disease in genetically predisposed but otherwise asymptomatic individuals. In this report, we show that normal pregnant mice have raised hepatic bile acid levels in the presence of procholestatic gene expression. The nuclear receptor farnesoid X receptor (FXR) regulates the transcription of the majority of these genes, and we show that both ablation and activation of Fxr prevent the accumulation of hepatic bile acids during pregnancy. These observations suggest that the function of Fxr may be perturbed during gestation. In subsequent in vitro experiments, serum from pregnant mice and humans was found to repress expression of the Fxr target gene, small heterodimer partner (Shp), in liver‐derived Fao cells. Estradiol or estradiol metabolites may contribute to this effect because coincubation with the estrogen receptor (ER) antagonist fulvestrant (ICI 182780) abolished the repressive effects on Shp expression. Finally, we report that ERα interacts with FXR in an estradiol‐dependent manner and represses its function in vitro. Conclusion: Ligand‐activated ERα may inhibit FXR function during pregnancy and result in procholestatic gene expression and raised hepatic bile acid levels. We propose that this could cause intrahepatic cholestasis of pregnancy in genetically predisposed individuals. HEPATOLOGY 2010

Serum Metabolic Profiling in Inflammatory Bowel Disease

BackgroundThe inflammatory bowel diseases (IBD), Crohn’s disease (CD), and ulcerative colitis (UC), are chronic inflammatory conditions of the gastrointestinal tract whose pathogenesis is not completely understood. 1H nuclear magnetic resonance (NMR) spectroscopy of serum generates comprehensive metabolic profiles, reflecting systemic metabolism, which may be altered in disease states.AimThe aim of this study was to use 1H NMR-based serum metabolic profiling in the investigation of CD patients, UC patients, and controls, potentially to provide insights into disordered metabolism in IBD, and into underlying mechanisms of disease.MethodsSerum metabolic profiles were acquired from 67 individuals (24 CD patients, 20 UC patients, and 23 healthy controls). The multivariate pattern-recognition techniques of principal components analysis (PCA) and partial least squares discriminant analysis with orthogonal signal correction (OSC-PLS-DA) were used to investigate differences between cohorts.ResultsOSC-PLS-DA distinguished CD and UC cohorts with significant predictive accuracy, highlighting differences in lipid and choline metabolism. Metabolic profiles of both CD and UC cohorts, and the combined IBD cohort, differed significantly from controls: metabolites of importance in the OSC-PLS-DA models included lipoproteins (especially HDL cholesterol), choline, N-acetylglycoprotein, and amino acids.Conclusions1H NMR-based metabolic profiling has identified distinct differences in serum metabolic phenotype between CD and UC patients, as well as between IBD patients and controls.

Incidental findings in healthy control research subjects using whole-body MRI

AIM Magnetic resonance imaging (MRI) is a powerful clinical tool used increasingly in the research setting. We aimed to assess the prevalence of incidental findings in a sequential cohort of healthy volunteers undergoing whole-body MRI as part of a normal control database for imaging research studies. MATERIALS AND METHODS 148 healthy volunteers (median age 36 years, range 21-69 years; 63.5% males, 36.5% females) were enrolled into a prospective observational study at a single hospital-based MRI research unit in London, UK. Individuals with a clinical illness, treated or under investigation were excluded from the study. RESULTS 43 (29.1%) scans were abnormal with a total of 49 abnormalities detected. Of these, 20 abnormalities in 19 patients (12.8%) were of clinical significance. The prevalence of incidental findings increased significantly with both increasing age and body mass index (BMI). Obese subjects had a fivefold greater risk of having an incidental abnormality on MRI (OR 5.4, CI 2.1-14.0). CONCLUSIONS This study showed that more than one quarter of healthy volunteers have MR-demonstrable abnormalities. There was an increased risk of such findings in obese patients. This has ethical and financial implications for future imaging research, particularly with respect to informed consent and follow-up of those with abnormalities detected during the course of imaging studies.

Hepatic lipid profiling in chronic hepatitis C: An in vitro and in vivo proton magnetic resonance spectroscopy study

BACKGROUND & AIMS Hepatic steatosis is an important factor in pathogenesis, progression and response to treatment in hepatitis C. We aimed to investigate differences in hepatic lipid composition in liver biopsies from patients with chronic hepatitis C using proton magnetic resonance spectroscopy ((1)H MRS) and to translate these findings to the in vivo clinical setting. METHODS Two cohorts of patients with histologically defined chronic hepatitis C were studied. High-resolution MR spectra were obtained from 47 liver biopsy samples. These data were used to derive biologically relevant prior knowledge for the assignment and interpretation of lower-resolution in vivo hepatic MRS data acquired at 1.5T from a second cohort of 59 patients. MRS data were obtained both in vitro and in vivo from a subset of 11 patients. RESULTS Multivariate factor analysis demonstrated characteristic MR spectral differences by fibrosis stage and genotype. Total lipid increased with fibrosis stage (r=0.43, p=0.003) and was higher in genotype 3 compared to genotype 1 (p=0.03), while lipid polyunsaturation decreased with increasing fibrosis stage (r=-0.55, p<0.0005) and, independently, with increasing steatosis. Non-invasive assessment using in vivo hepatic (1)H MRS corroborated in vitro findings, but the signal-to-noise ratio was insufficient for reliable assessment of lipid polyunsaturation in vivo. CONCLUSIONS Hepatic lipid composition was analysed using MRS in patients with chronic hepatitis C in vitro and in vivo, demonstrating significant differences in indices by disease severity. High-resolution data informed the analysis and interpretation of in vivo spectra, but further improvements in spectral quality in vivo are required.

Phenotyping murine models of non-alcoholic fatty liver disease through metabolic profiling of intact liver tissue

NAFLD (non-alcoholic fatty liver disease) is a common cause of chronic liver disease associated with the metabolic syndrome. Effective techniques are needed to investigate the potential of animal models of NAFLD. The present study aimed to characterize murine models of NAFLD by metabolic profiling of intact liver tissue. Mice of three strains (BALB/c, C3H and the novel mutant, Gena/263) were fed a control or high-fat diet. Biometric, biochemical and histological analysis demonstrated a spectrum of NAFLD from normal liver to steatohepatitis. Metabolic profiling of intact liver tissue, using (1)H MAS (proton magic angle spinning) MRS (magnetic resonance spectroscopy), showed an increase in the total lipid-to-water ratio, a decrease in polyunsaturation indices and a decrease in total choline with increasing disease severity. Principal components analysis and partial least-squares discriminant analysis showed separation of each model from its control and of each model from the total dataset. Class membership from the whole dataset was predicted with 100% accuracy in six out of eight models. Those models with steatosis discriminated from those with steatohepatitis with 100% accuracy. The separation of histologically defined steatohepatitis from simple steatosis is clinically important. Indices derived from (1)H MAS MRS studies may inform subsequent in vivo MRS studies at lower field strengths.

Assessment of inflammation and fibrosis in non‐alcoholic fatty liver disease by imaging‐based techniques

Non‐alcoholic fatty liver disease (NALFD) is a burgeoning global health problem, and the assessment of disease severity remains a clinical challenge. Conventional imaging and clinical blood tests are frequently unable to determine disease activity (the degree of inflammatory change) and fibrotic severity, while the applicability of histological examination of liver biopsy is limited. Imaging platforms provide liver‐specific structural information, while newer applications of these technologies non‐invasively exploit the physical and chemical characteristics of liver tissue in health and disease. In this review, conventional and newer imaging‐based techniques for the assessment of inflammation and fibrosis in NAFLD are discussed in terms of diagnostic accuracy, radio‐pathological correlations, and practical considerations. In particular, recent clinical studies of ultrasound (US)‐based and magnetic resonance elastography techniques are evaluated, while the potential of contrast‐enhanced US and magnetic resonance spectroscopy techniques is discussed.

Transient elastography in acute hepatitis: All that's stiff is not fibrosis

Two papers in this issue of HEPATOLOGY examine the effect of inflammation on liver stiffness measurement (LSM), as assessed by transient elastography (Arena and Vizzutti et al.,1Sagir et al.2). These papers challenge the commonly held assumption that liver stiffness is determined solely by the severity of hepatic fibrosis. Such a view is underpinned by the clinical experience that, on palpation, a cirrhotic liver is hard, and experimentally, by the correlation of stiffness (elastic modulus) with the histopathological fibrosis score in ex vivo hepatic samples.3 However, in the proof-of-principle study by Yeh and colleagues,3 it was stressed that “biological tissue is a composite material and it is difficult to separate the influence of each component of the tissue on the total of modulus estimates”. Demonstration that biological variables other than fibrosis contribute to LSM, therefore comes as no surprise. The development of transient elastography was a leap forward, enabling the rapid acquisition of objective liver stiffness measurements in vivo.4 In the seminal work by Sandrin and colleagues,4 a cohort of patients with chronic hepatitis C was studied. This patient group is appropriate for study as the natural history of the disease and its histological classification is well established, the prevalence of the disease is high in many countries and effective treatment options are available.5-7 Multiple regression analysis in early studies demonstrated a relationship between elasticity measurements and fibrosis stage, but not to the disease activity (or necroinflammatory score), nor to the degree of steatosis.4,8 However, the observation that the range of liver stiffness values obtained in patients with cirrhosis was very large led to speculation that there may be a relationship between portal hypertension and liver stiffness.4 Subsequently, a number of well-conducted studies confirmed the correlation between liver stiffness and hepatic fibrosis in hepatitis C,8,9 and other chronic hepatic conditions.10-12 However, studies have also indicated the presence of co-existing factors that contribute to liver stiffness. Area under the receiver operator characteristic (AUROC) curves plot sensitivity and specificity for all possible cutoff values between two given states, giving a measure of diagnostic accuracy. Accordingly, quoted cutoff values vary between patient cohorts with the same disease, between cohorts of differing diseases and according to whether the operator requires a cutoff value which gives maximal sensitivity or specificity.10,11 While the prevalence of a disease in the population studied affects the diagnostic accuracy, the presence of disease-specific factors other than fibrosis stage alone may also contribute to differences in LSM. Substantial differences in cutoff values for cirrhosis have been observed between those with chronic hepatitis and those with alcohol-related chronic liver disease and non-alcoholic fatty liver disease (NAFLD).11,12 While the inter-test and inter-rater reliability for LSM was found to be excellent (intraclass correlation of 0.98) in a cohort of 200 patients with chronic liver disease in Italy, the reliability of measurements in overweight individuals and those with NAFLD as assessed by the intraclass correlation coefficient is reduced.13 However, in that study cohort, the mean BMI was just 24.8 kg/m2, which is lower than that found in many populations. As such, it was under-powered to examine the effects of obesity and NAFLD on the reliability of LSM. On the basis of clinical experience, LSM is difficult to perform successfully and reliably in obese individuals. Current evidence does not demonstrate an independent effect of hepatic steatosis on LSM, but it remains to be seen whether steatosis per se systematically alters LSM in a study where patients are stratified primarily by a validated method for lipid quantitation, such as proton magnetic resonance spectroscopy.14 A number of studies have pointed to a relationship between portal hypertension and liver stiffness measureAbbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; AUROC, area under the receiver operator characteristic; HPVG, hepatic venous pressure gradient; LSM, liver stiffness measurement; NAFLD, nonalcoholic fatty liver disease. JFLC holds the Centenary Fellowship from the Hammersmith Hospitals Trustees Research Committee. SDTR holds grants from Engineering, Physics and Science Research Council, Swindon, UK; Medical Research Council, London, UK; AMMF, Essex, UK; Broad Foundation, Los Angeles, USA; Pfizer Global Research and Development Inc, Sandwich, UK and GlaxoSmithKline, Ware, UK. Address reprint requests to: Professor S.D. Taylor-Robinson, M.D., FRCP, Department of Hepatology, Division of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0HS United Kingdom. E-mail: s.taylor-robinson@imperial.ac.uk and j.cobbold@imperial.ac.uk; fax: (44) 20 8383 3038. Copyright

Optimal combinations of ultrasound-based and serum markers of disease severity in patients with chronic hepatitis C

Summary.  Combinations of noninvasive markers may improve discrimination of chronic liver disease severity. The aims of this study were to compare four validated serum and ultrasound‐based markers of hepatic disease severity head‐to‐head with liver biopsy and to assess optimal combinations with consideration of cost. A total of 67 patients with biopsy‐proven chronic hepatitis C underwent all four techniques on the same visit [aspartate aminotransferase (AST) to platelet ratio index (APRI); Enhanced Liver Fibrosis (ELF) panel; transient elastography (TE) and ultrasound microbubble hepatic transit times (HTT)]. Markers were combined according to increasing financial cost and ordinal regression used to determine contributions. APRI, ELF, TE and HTT predicted cirrhosis with diagnostic accuracy of 86%, 91%, 90% and 83% respectively. ELF and TE were the most reliable tests with an intra‐class correlation of 0.94 each. Either ELF or TE significantly enhanced the prediction of fibrosis stage when combined with APRI, but when combined together, did not improve the model further. Addition of third or fourth markers did not significantly improve prediction of fibrosis. Combination of APRI with either ELF or TE effectively predicts fibrosis stage, but combinations of three or more tests lead to redundancy of information and increased cost.

Multiparametric magnetic resonance imaging for the assessment of non-alcoholic fatty liver disease severity.

The diagnosis of non‐alcoholic steatohepatitis and fibrosis staging are central to non‐alcoholic fatty liver disease assessment. We evaluated multiparametric magnetic resonance in the assessment of non‐alcoholic steatohepatitis and fibrosis using histology as standard in non‐alcoholic fatty liver disease.