Noninvasive assessment of liver disease severity in patients with nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes.

BACKGROUND AND AIMS: We evaluated the diagnostic accuracy of simple, noninvasive tests (NITs) in NAFLD patients with type 2 diabetes (T2D). METHODS AND RESULTS: This was an individual patient data meta-analysis of 1780 patients with biopsy-proven NAFLD and T2D. The index tests of interest were FIB-4, NAFLD Fibrosis Score (NFS), aspartate aminotransferase-to-platelet ratio index, liver stiffness measurement (LSM) by vibration-controlled transient elastography, and AGILE 3+. The target conditions were advanced fibrosis, NASH, and fibrotic NASH(NASH plus F2-F4 fibrosis). The diagnostic performance of noninvasive tests. individually or in sequential combination, was assessed by area under the receiver operating characteristic curve and by decision curve analysis. Comparison with 2278 NAFLD patients without T2D was also made. In NAFLD with T2D LSM and AGILE 3+ outperformed, both NFS and FIB-4 for advanced fibrosis (area under the receiver operating characteristic curve:LSM 0.82, AGILE 3+ 0.82, NFS 0.72, FIB-4 0.75, aspartate aminotransferase-to-platelet ratio index 0.68; p < 0.001 of LSM-based versus simple serum tests), with an uncertainty area of 12%-20%. The combination of serum-based with LSM-based tests for advanced fibrosis led to a reduction of 40%-60% in necessary LSM tests. Decision curve analysis showed that all scores had a modest net benefit for ruling out advanced fibrosis at the risk threshold of 5%-10% of missing advanced fibrosis. LSM and AGILE 3+ outperformed both NFS and FIB-4 for fibrotic NASH (area under the receiver operating characteristic curve:LSM 0.79, AGILE 3+ 0.77, NFS 0.71, FIB-4 0.71; p < 0.001 of LSM-based versus simple serum tests). All noninvasive scores were suboptimal for diagnosing NASH. CONCLUSIONS: LSM and AGILE 3+ individually or in low availability settings in sequential combination after FIB-4 or NFS have a similar good diagnostic accuracy for advanced fibrosis and an acceptable diagnostic accuracy for fibrotic NASH in NAFLD patients with T2D.

PYY plays a key role in the resolution of diabetes following bariatric surgery in humans.

BACKGROUND: Bariatric surgery leads to early and long-lasting remission of type 2 diabetes (T2D). However, the mechanisms behind this phenomenon remain unclear. Among several factors, gut hormones are thought to be crucial mediators of this effect. Unlike GLP-1, the role of the hormone peptide tyrosine tyrosine (PYY) in bariatric surgery in humans has been limited to appetite regulation and its impact on pancreatic islet secretory function and glucose metabolism remains under-studied. METHODS: Changes in PYY concentrations were examined in obese patients after bariatric surgery and compared to healthy controls. Human pancreatic islet function was tested upon treatment with sera from patients before and after the surgery, in presence or absence of PYY. Alterations in intra-islet PYY release and insulin secretion were analysed after stimulation with short chain fatty acids (SCFAs), bile acids and the cytokine IL-22. FINDINGS: We demonstrate that PYY is a key effector of the early recovery of impaired glucose-mediated insulin and glucagon secretion in bariatric surgery. We establish that the short chain fatty acid propionate and bile acids, which are elevated after surgery, can trigger PYY release not only from enteroendocrine cells but also from human pancreatic islets. In addition, we identify IL-22 as a new factor which is modulated by bariatric surgery in humans and which directly regulates PYY expression and release. INTERPRETATION: This study shows that some major metabolic benefits of bariatric surgery can be emulated ex vivo. Our findings are expected to have a direct impact on the development of new non-surgical therapy for T2D correction.

Rifaximin in non-alcoholic steatohepatitis: An open-label pilot study.

AIM: Gut microbial dysbiosis is implicated in the pathogenesis of non-alcoholic steatohepatitis (NASH). We investigated downstream effects of gut microbiota modulation on markers of hepatic inflammation, steatosis, and hepatic and peripheral insulin sensitivity in patients with NASH using rifaximin therapy. METHODS: Patients with biopsy-proven NASH and elevated aminotransferase values were included in this open-label pilot study, all receiving 6 weeks rifaximin 400 mg twice daily, followed by a 6-week observation period. The primary endpoint was change in alanine aminotransferase (ALT) after 6 weeks of rifaximin. Secondary endpoints were change in hepatic lipid content and insulin sensitivity measured with a hyperinsulinemic-euglycemic clamp. RESULTS: Fifteen patients (13 men and 2 women) with a median (range) age of 46 (32-63) years were included. Seven had diabetes on oral hypoglycemic medications and 8 had no diabetes. After 6 weeks of therapy, no differences were seen in ALT (55 [33-191] vs. 63 [41-218] IU/L, P = 0.41), peripheral glucose uptake (28.9 [19.4-48.3] to 25.5 [17.7-47.9] µmol/kg/min, P = 0.30), hepatic insulin sensitivity (35.2 [15.3-51.7]% vs. 30.0 [10.8-50.5]%, P = 0.47), or hepatic lipid content (21.6 [2.2-46.2]% vs. 24.8 [1.7-59.3]%, P = 0.59) before and after rifaximin treatment. After 12 weeks from baseline, serum ALT increased to 83 (30-217) IU/L, P = 0.02. There was a significant increase in the homeostasis model assessment-estimated insulin resistance index (P = 0.05). The urinary metabolic profile indicated a significant reduction in urinary hippurate with treatment, which reverted to baseline after cessation of rifaximin, although there was no consistent difference in relative abundance of fecal microbiota with treatment. CONCLUSION: These data do not indicate a beneficial effect of rifaximin in patients with NASH.

Changes in Liver Volume in Patients with Chronic Hepatitis C Undergoing Antiviral Therapy.

AIM: Liver volumetric analysis has not been used to detect hepatic remodelling during antiviral therapy before. We measured liver volume (LV) changes on volumetric magnetic resonance imaging during hepatitis C antiviral therapy. METHODS: 22 biopsy-staged patients (median [range] age 45(19-65) years; 9F, 13M) with chronic hepatitis C virus infection were studied. LV was measured at the beginning, end of treatment and 6 months post-treatment using 3D T1-weighted acquisition, normalised to patient weight. Liver outlines were drawn manually on 4 mm thick image slices and LV calculated. Inter-observer agreement was analysed. Patients were also assessed longitudinally using biochemical parameters and liver stiffness using Fibroscan™. RESULTS: Sustained viral response (SVR) was achieved in 13 patients with a mean baseline LV/kg of 0.022 (SD 0.004) L/kg. At the end of treatment, the mean LV/kg was 0.025 (SD 0.004, P = 0.024 cf baseline LV/kg) and 0.026 (SD 0.004, P = 0.008 cf baseline LV/kg) 6 months post-treatment (P = 0.030 cf baseline, P = 0.004). Body weight-corrected end of treatment LV change was significantly higher in patients with SVR compared to patients not attaining SVR (P = 0.050). End of treatment LV change was correlated to initial ALT (R (2) = 0.479, P = 0.037), but not APRI, AST, viral load or liver stiffness measurements. There was a correlation of 0.89 between observers for measured slice thickness. CONCLUSIONS: LV increased during anti-viral treatment, while the body weight-corrected LV increase persisted post-antiviral therapy and was larger in patients with SVR.

Piloting a multidisciplinary clinic for the management of non-alcoholic fatty liver disease: initial 5-year experience.

OBJECTIVE: A multidisciplinary approach is advocated for the management of Non-Alcoholic Fatty Liver Disease (NAFLD), but few clinical data exist to support this. The objective of this study was to investigate the effectiveness of a multidisciplinary NAFLD clinic using surrogate markers of liver injury and cardiovascular risk. DESIGN: Retrospective survey of clinical practice. SETTING: The multidisciplinary NAFLD clinic in a secondary/tertiary care setting with hepatology, diabetology, dietetic and exercise therapy input: initial 5-years' experience (2007-2012). PATIENTS: 180 patients with NAFLD but without hepatic comorbidities were followed up for a median of 19.5 (range 3-57) months. 52% had type 2 diabetes mellitus, 48% were Europoid Caucasian, 17% were South Asian. INTERVENTIONS: Multiple clinical interventions were employed including lifestyle (diet and exercise) advice, pharmacological intervention for cardiovascular risk factors, weight loss and exercise therapy. MAIN OUTCOME MEASURES: Change in alanine aminotransferase (ALT), weight, HbA1c, lipid profile and blood pressure. RESULTS: Median ALT fell from 61 (12-270) U/l to 50 (11-221) U/l, -18%, p<0.001, and weight fell from 90.5 (42.7-175.0) kg to 87.3 (45.9-175.3) kg, -3.5%, p<0.001. There were significant improvements in total cholesterol overall, triglycerides (among dyslipidaemic patients), HbA1c (among diabetic patients) and systolic blood pressure (among hypertensive patients). 24% of patients achieved ≥7% weight loss during follow-up and 17% maintained this weight loss throughout. CONCLUSIONS: Improvement in liver biochemistry and cardiovascular risk factors was seen in patients attending the multidisciplinary NAFLD clinic. Refinement of this approach is warranted in light of these data, novel therapies and a growing evidence base.

Lipid profiling of pre-treatment liver biopsy tissue predicts sustained virological response in patients with chronic hepatitis C.

AIM: Hepatic lipid is important in the pathogenesis and progression of hepatitis C-related liver disease. Polyunsaturated fatty acids have been shown to reduce viral replication in cell culture. Proton magic angle spinning magnetic resonance spectroscopy ((1) H MAS MRS) enables metabolic analysis of intact tissue. The aim was to examine the relationship between hepatic lipid composition by metabolic profiling of liver tissue at baseline and treatment response to pegylated-Interferon alfa2 and Ribavirin. METHODS: Baseline liver biopsy samples from 31 patients with chronic hepatitis C were analyzed histologically and by (1) H MAS MRS. Indices of lipid composition were derived and partial least squares discriminant analysis with cross-validation was used to predict treatment outcome. RESULTS: Of 31 patients, 14 achieved sustained virological response (SVR). Lipid polyunsaturation (median (IQR)) was higher in SVR (3.41% (2.31)) than in treatment failure (TF) (2.15% (1.51)), P = 0.02. Lipid saturation was lower in SVR (85.9% (3.39)) than TF (86.7% (2.17)), P = 0.04. The total lipid content was lower in SVR (1.54% (0.81)) than TF (2.72% (3.47)), P = 0.004. Total choline to lipid ratio was higher in SVR (11.51% (9.99)) than TF (7.5% (6.82)), P = 0.007. Cross-validation correctly predicted the SVR group in 13 of 14 samples with 1 sample misclassified, and the TF group in all 17 samples. CONCLUSIONS: Lipid polyunsaturation was greater and total lipid lower in those with SVR, compared with TF. Metabolic profiling of intact liver biopsy samples predicted SVR with high accuracy. Hepatic lipid composition may impact on treatment success.

Accuracy and reliability of microbubble ultrasound measurements for the non-invasive assessment of hepatic fibrosis in chronic hepatitis C.

AIM: Contrast-enhanced ultrasound can be used to assess liver disease severity non-invasively by observing intra- and extrahepatic hemodynamic changes. Transit times are calculated to include intra- and extrahepatic components (hepatic vein transit time, HVTT) or the intrahepatic component (hepatic transit time, HTT), but these have not been compared directly. We aimed to compare diagnostic accuracy of HVTT and HTT in gauging the severity of chronic hepatitis C (CHC) and to assess inter- and intra-observer reliability. METHODS: Recorded ultrasound scans performed on 75 patients with biopsy-staged CHC, using the microbubble contrast agent Sonovue were analyzed. RESULTS: Diagnostic accuracy of HTT and HVTT for diagnosis of cirrhosis was 0.78 and 0.71 (P = 0.24). Diagnostic accuracy of HTT and HVTT for diagnosis of fibrosis stage >2 was 0.76 and 0.72 (P = 0.23). Negative predictive value for cirrhosis using this cut-off was high for both techniques (HVTT, 88%; HTT, 92%), suggesting utility for exclusion of cirrhosis. Inter-observer reliability for HTT and HVTT were 0.92 and 0.94, respectively. Intra-observer reliability for HTT and HVTT were 0.98 and 0.99. CONCLUSION: In this cohort, reliability exceeded 90% while diagnostic accuracy was in keeping with previous studies of microbubble transit time analysis. Despite higher numerical diagnostic accuracy for HTT, no significant difference was demonstrated between the techniques, suggesting that both methods can be used reliably.

Serum metabolic profiling in inflammatory bowel disease.

BACKGROUND: The 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. (1)H nuclear magnetic resonance (NMR) spectroscopy of serum generates comprehensive metabolic profiles, reflecting systemic metabolism, which may be altered in disease states. AIM: The aim of this study was to use (1)H 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. METHODS: Serum 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. RESULTS: OSC-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. CONCLUSIONS: (1)H 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.

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. The development and application of these techniques is starting to reduce the clinical need for liver biopsy, to produce surrogate end-points for interventional and observational clinical studies, and through this, to provide new insights into the natural history of NAFLD.

Metabolic profiling of the rat liver after chronic ingestion of alpha-naphthylisothiocyanate using in vivo and ex vivo magnetic resonance spectroscopy.

Certain human diseases affecting the biliary tree can be modeled in rats by ingestion of the hepatobiliary toxin alpha-naphthylisothiocyanate (ANIT). Phosphorus magnetic resonance spectroscopy (MRS) allows the noninvasive monitoring of cell dynamics through detection of phosphodiesters (PDE) and phosphomonoesters (PME). Hepatic (31)P MRS techniques were therefore used to study the toxic effects of low-dose chronic ANIT ingestion, with a view toward providing biomarkers sensitive to hepatobiliary dysfunction and cholestatic liver injury. Rats were fed an ANIT supplemented diet at three doses (ANIT_0.05%, ANIT_0.04%, and ANIT_0.025%) for 2 weeks. Data from in vivo MRS were compared with results from pair-fed controls (PFCs). Blood and tissue samples were collected at 2 weeks for clinical chemistry, histology, and (1)H magic angle spinning MRS. Increases in PDE, relative to total phosphorus (tPh), were detected in both the ANIT_0.05% and ANIT_0.04% groups (0.07 ± 0.01 and 0.08 ± 0.01, respectively) relative to PFC groups (0.03 ± 0.01 and 0.05 ± 0.01, respectively). An increase in PME/tPh was observed in the ANIT_0.05% group only (0.17 ± 0.02) relative to PFC_0.05% (0.12 ± 0.01). Ex vivo (1)H MRS findings supported this, wherein measured phosphocholines (PCs) were increased in ANIT_0.05% and ANIT_0.04% groups. Increases in relative total choline (tCho) distinguished the ANIT_0.05% group from the ANIT_0.04% group. Markers of hepatotoxicity such as raised total bilirubin and alkaline phosphatase were found at all ANIT doses. Histological findings included a dose-related increase in both severity of biliary hyperplasia and focal hepatocellular necrosis. Here, we found that ANIT-induced moderate hepatobiliary dysfunction was associated with a relative increase in phosphodiesters in vivo and PCs ex vivo. Raised PME/tPh in vivo and tCho ex vivo were also present at high doses corresponding to a higher incidence of marked biliary hyperplasia and moderate hepatocellular necrosis.

A comparison of single-voxel clinical in vivo hepatic 31P MR spectra acquired at 1.5 and 3.0 Tesla in health and diseased states.

With the increasing availability of human MR scanners at various field strengths, the optimal field strength for in vivo clinical MR studies of the liver has become a focus of attention. Comparison between results at 3.0 and 1.5 T is of particular clinical interest, especially for multicentre studies. For MRS studies, higher field strengths should be advantageous, because improved sensitivity and chemical shift dispersion are expected. We report a comparison between single-voxel hepatic proton-decoupled (31)P MRS performed at 1.5 and 3.0 T in the same subjects using similar methodologies. Twelve healthy volunteers and 15 patients with chronic liver disease were studied. Improved spectral resolution was achieved using proton decoupling, and there was an improvement (21%) in the signal-to-noise ratio (SNR) of the phosphomonoester (PME) resonance at 3.0 T relative to 1.5 T. There was no significant change in nuclear Overhauser effects for PME or phosphodiesters (PDEs) between the two field strengths. The T(1) value of PDE was significantly longer at 3 T, although there was no significant change in the T(1) value of PME. There was no significant difference in the mean PME/PDE ratios for either the control or patient groups at both 1.5 and 3.0 T, but there was a small positive mean difference in PME/PDE at 3.0 T on pairwise testing between field strengths (+ 0.05, p < 0.01). There were significant correlations between PME/PDE values at the two magnetic field strengths (r = 0.806, p < 0.001). The underlying broad resonance was reduced at 3.0 T relative to 1.5 T, related to line broadening of the phospholipid bilayer signal. In conclusion, there was an improvement in hepatic (31)P MR signal quality at 3.0 T relative to 1.5 T. Broadly similar hepatic (31)P MR parameters were obtained at 1.5 and 3.0 T. The modest difference noted in the PME/PDE ratio between field strengths for patients with chronic liver disease should inform multicentre study design involving these field strengths.

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

UNLABELLED: 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.

Differences in gut microbial metabolism are responsible for reduced hippurate synthesis in Crohn's disease.

BACKGROUND: Certain urinary metabolites are the product of gut microbial or mammalian metabolism; others, such as hippurate, are mammalian-microbial 'co-metabolites'. It has previously been observed that Crohn's disease (CD) patients excrete significantly less hippurate than controls. There are two stages in the biosynthesis of this metabolite: 1) gut microbial metabolism of dietary aromatic compounds to benzoate, and 2) subsequent hepatorenal conjugation of benzoate with glycine, forming hippurate. Differences in such urinary co-metabolites may therefore reflect systemic consequences of altered gut microbial metabolism, though altered host metabolic pathways may also be involved. METHODS: It was hypothesised that reduced hippurate excretion in CD patients was due to alterations in the gut microbiota, and not differences in dietary benzoate, nor defective host enzymatic conjugation of benzoate. 5 mg/kg sodium benzoate were administered orally to 16 CD patients and 16 healthy controls on a low-benzoate diet. Baseline and peak urinary hippurate excretion were measured. RESULTS: Baseline hippurate levels were significantly lower in the CD patients (p = 0.0009). After benzoate ingestion, peak urinary levels of hippurate did not differ significantly between the cohorts. Consequently the relative increase in excretion was significantly greater in CD (p = 0.0007). CONCLUSIONS: Lower urinary hippurate levels in CD are not due to differences in dietary benzoate. A defect in the enzymatic conjugation of benzoate in CD has been excluded, strongly implicating altered gut microbial metabolism as the cause of decreased hippurate levels in CD.

The importance of fatty liver disease in clinical practice.

The worldwide obesity epidemic over the last 20 years has led to a dramatic increase in the prevalence of non-alcoholic fatty liver disease, the hepatic manifestation of the metabolic syndrome. Estimates of prevalence vary depending on the population studied and the methods used to assess hepatic fat content, but are commonly quoted as between 10 and 30% of the adults in the Western hemisphere. Fatty liver develops when fatty acid uptake and synthesis in the liver exceeds fatty acid oxidation and export as TAG. Studies of pathogenesis point to insulin resistance, lipotoxicity, oxidative stress and chronic inflammation being central to the development and progression of the disease. A proportion of individuals with fatty liver develop progressive disease, though large prospective longitudinal studies are lacking. Nevertheless, fatty liver is associated with increased all-cause and liver-related mortality compared with the general population. Management of fatty liver centres around lifestyle and dietary measures to induce controlled and sustained weight loss. Management of cardiovascular risk factors aims to reduce mortality, while certain dietary interventions have been shown to reduce steatosis and inflammation. Specific pharmacological treatments also show promise, but their use is not widespread. A multi-system and multi-disciplinary approach to the management of this disorder is proposed.

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.