The overarching aim of LITMUS is to develop, robustly validate and advance towards regulatory qualification biomarkers that diagnose, risk stratify and/or monitor NAFLD/NASH progression and fibrosis stage. This will be achieved through a goal-oriented, tri-partite collaboration delivering a definitive and impartial evaluation platform for biomarkers, bringing together: (i) End-users of biomarker technologies (clinicians with expertise in NAFLD and the pharmaceutical industry); (ii) Independent academics with expertise in the evaluation of medical test/biomarker performance; and (iii) Biomarker researchers and developers (academic or commercial).

For deliverable D3.2, we aimed to validate a 7-tier histological staging system for NAFLD-associated fibrosis using digital slides. The EPOS staging system is a 7-tier system for semi-quantitating the extent of fibrosis that has been created and tested by the EPOS Histopathology Group, members of which are included in the LITMUS Histopathology Group – LHG (Bedossa, J Hepatol 2018).

The performance of biomarkers in LITMUS has to be evaluated against well-defined criteria for acceptability. For this purpose,  the context of use/minimally acceptable performance criteria document is prepared by LITMUS partners. These criteria include a definition of the context of use, the appropriate target condition(s), acceptable reference standard, required clinical evidence, and minimum levels of accuracy measurements. The whole document could be accessed here and is meant to be a “living” resource, further modified, if needed, in the course of the LITMUS project and will be periodically updated with additional terms and clarifying information.

Poster presentation by Funuyet-Salas, J. et al at the EASL International Liver Congress, Vienna, Austria, 21^st – 24^th June 2023
“Histological and biopsychosocial predictors of quality of life in Spanish and UK cohorts of patients with Non-Alcoholic Fatty Liver Disease”

Poster presentation by Govaere, O. et al at EASL International Liver Congress, London, UK, 22^nd – 26^th June 2022
“Signature of circulating hepatic proteins detects fibrosing steatohepatitis in progressive Non-alcoholic Fatty Liver Disease”

Poster presentation by Williams, B.J.M. & DeLisle, R.K. at the 19th Annual US HUPO Conference, Chicago, IL, USA, 4^th – 8^th March 2023
“Topic Modeling the Human Plasma Proteome: An Unsupervised Learning Method for Proteomic Analysis”

Poster presentation by Simpson, M. et al at the AASLD Liver Meeting, Boston, MA, USA, 4^th – 8^th November 2022
“Proteomic markers of cardiovascular and metabolic health in at-risk NASH”

Poster presentation by Liang, J. et al at the EASL International Liver Congress, London, UK, 22^nd – 26^th June 2022
“Establishing the Cut-offs and Confounding factors of Magnetic Resonance Elastography for staging NAFLD-fibrosis: an IPD meta-analysis”

Poster presentation by Mózes, F.E. et al at the EASL International Liver Congress, London, UK, 22^nd – 26^th June 2022
“Determinants of liver stiffness measurements in patients with NAFLD – an individual patient data meta-analysis”

Poster presentation by Mózes, F.E. et al at the EASL International Liver Congress, London, UK, 22^nd – 26^th June 2022
“Diagnostic accuracy of non-invasive tests for fibrotic NASH – An individual participant data meta-analysis”

Poster presentation by Mózes, F.E. et al at the EASL International Liver Congress, London, UK, 22^nd – 26^th June 2022
“Diagnostic accuracy of non-invasive tests for cirrhotic NASH – An individual participant data meta-analysis”

Poster presentation by Liang, J-X. et al at the EASL International Liver Congress, London, UK, 22^nd – 26^th June 2022
“Establishing the Cut-offs and Confounding factors of Magnetic Resonance Elastography for staging NAFLD-fibrosis: an IPD meta-analysis”

Poster presentation by Romero, C.L. et al at the EASL International Liver Congress, London, UK, 22^nd – 26^th June 2022
“Liver stiffness assessment by MR elastography in histologically proven non-alcoholic fatty liver disease patients: a Spanish cohort”

Poster presentation by Vali, Y. et al at the EASL Digital International Liver Congress, 23^rd – 26^th June 2021
“Biomarker screening strategies to identify at-risk NASH cases for clinical trial recruitment in NAFLD”

Poster presentation by Vali, Y. et al at the EASL Digital International Liver Congress, 23^rd – 26^th June 2021
“Comparative diagnostic accuracy of blood-based biomarkers for diagnosing NASH: phase 1 results of the LITMUS project”

Poster presentation by Erhardtsen, E. et al at the AASLD Liver Meeting, 13^th – 16^th November 2020
“Interactions with FDA and EMA: The LITMUS experience from qualification advice on biomarkers in NASH”

Poster presentation by Whalley, D. et al at the EASL Digital International Liver Congress, 27^th – 29^th August 2020
“Patient-Reported Symptoms and Impact in Nonalcoholic Steatohepatitis: An Evaluation of the NASH-CHECK, a Novel PROM in NASH”

Poster presentation by Breckons, M. et al at the EASL Digital International Liver Congress, 27^th – 29^th August 2020
“Evaluating the patient-perceived impact of non-alcoholic steatohepatitis with compensated cirrhosis”

Poster presentation by Younes, R. et al at the EASL Digital International Liver Congress, 27^th – 29^th August 2020
“Insulin secretion is an independent predictor of hepatic ballooning in non-diabetic subjects with non-alcoholic fatty liver disease”

Poster presentation by Rosso, C. et al at the EASL Digital International Liver Congress, 27^th – 29^th August 2020
“Interplay between metabolic derangement, biomarkers of collagen remodeling and macrophage activation in non-diabetic patients with non-alcoholic fatty liver disease”

Poster presentation by Lee, J. et al at the EASL Digital International Liver Congress, 27^th – 29^th August 2020
“Accuracy of CK-18 (M30 and M65) in detecting NASH and fibrosis: a systematic review and meta-analysis”

Poster presentation by Selvaraj, E. et al at the EASL Digital International Liver Congress, 27th – 29th August 2020
“Diagnostic accuracy of acoustic radiation force impulse elastography for the staging of hepatic fibrosis in non-alcoholic fatty liver disease: a systematic review and meta-analysis”

Poster presentation by Mozes, F. et al at the EASL Digital International Liver Congress, 27th – 29th August 2020
“Diagnostic accuracy of magnetic resonance elastography for the staging of fibrosis and diagnosis of steatohepatitis in patients with non-alcoholic fatty liver disease: a systematic review and meta-analysis”

Poster presentation by Hvid, H. et al at the 3^rd Global NASH Congress, London, UK, 11^th February 2020
“Liver stiffness assessed with Shear Wave Elastography correlates with biopsy data in Gottingen Minipigs with non-alcoholic steatohepatitis”

Poster presentation by Johnson, K. et al at the AASLD Liver Meeting, Boston, MA, USA, 8^th – 12^th November 2019
“High-throughput detection of novel circulating miRNA biomarkers of non-alcoholic fatty liver disease”

Poster presentation by Rosso, C. et al, at EASL International Liver Congress, Vienna, Austria, 10^th – 14^th April 2019
“Selenoprotein P levels discriminate the degree of hepatic steatosis and are related to the NAS score in patients with Non-Alcoholic Fatty Liver Disease”

Poster presentation by Carli, F. et al, at EASL International Liver Congress, Paris, France, 11^th – 15^th April 2018
“In non obese NAFLD increased plasma saturated fatty acids and insulin resistance are metabolic signatures of severity of liver disease”

Poster presentation by Svegliati-Baroni, G. et al, at EASL International Liver Congress, Paris, France, 11^th – 15^th April 2018
“Predisposition to diabetes is related to insulin resistance in NAFLD patients and to decreased insulin secretion in HCV patients”

Journal article: Pavlides, M. et al, “Liver Investigation: Testing Marker Utility in Steatohepatitis (LITMUS): Assessment & Validation of Imaging Modality Performance across the NAFLD Spectrum in a Prospectively Recruited Cohort Study (The LITMUS Imaging Study): Study Protocol”, Contemporary Clinical Trials 134, November 2023

Abstract
Non-alcoholic fatty liver disease (NAFLD) is the liver manifestation of the metabolic syndrome with global prevalence reaching epidemic levels. Despite the high disease burden in the population only a small proportion of those with NAFLD will develop progressive liver disease, for which there is currently no approved pharmacotherapy. Identifying those who are at risk of progressive NAFLD currently requires a liver biopsy which is problematic. Firstly, liver biopsy is invasive and therefore not appropriate for use in a condition like NAFLD that affects a large proportion of the population. Secondly, biopsy is limited by sampling and observer dependent variability which can lead to misclassification of disease severity. Non-invasive biomarkers are therefore needed to replace liver biopsy in the assessment of NAFLD. Our study addresses this unmet need.The LITMUS Imaging Study is a prospectively recruited multi-centre cohort study evaluating magnetic resonance imaging and elastography, and ultrasound elastography against liver histology as the reference standard. Imaging biomarkers and biopsy are acquired within a 100-day window. The study employs standardised processes for imaging data collection and analysis as well as a real time central monitoring and quality control process for all the data submitted for analysis. It is anticipated that the high-quality data generated from this study will underpin changes in clinical practice for the benefit of people with NAFLD.

Journal article: Liang, J-X. et al, “An individual patient data meta-analysis to determine cut-offs for and confounders of NAFLD-fibrosis staging with magnetic resonance elastography”, Journal of Hepatology 79(3), September 2023

Abstract
Background & Aims: We conducted an individual patient data meta-analysis to establish stiffness cut-off values for magnetic resonance elastography (MRE) in staging liver fibrosis and to assess potential confounding factors.
Methods: A systematic review of the literature identified studies reporting MRE data in patients with NAFLD. Data were obtained from the corresponding authors. The pooled diagnostic cut-off value for the various fibrosis stages was determined in a two-stage meta-analysis. Multilevel modelling methods were used to analyse potential confounding factors influencing the diagnostic accuracy of MRE in staging liver fibrosis.
Results: Eight independent cohorts comprising 798 patients were included in the meta-analysis. The area under the receiver operating characteristic curve (AUROC) for MRE in detecting significant fibrosis was 0.92 (sensitivity, 79%; specificity, 89%). For advanced fibrosis, the AUROC was 0.92 (sensitivity, 87%; specificity, 88%). For cirrhosis, the AUROC was 0.94 (sensitivity, 88%, specificity, 89%). Cut-offs were defined to explore concordance between MRE and histopathology: ≥F2, 3.14 kPa (pretest probability, 39.4%); ≥F3, 3.53 kPa (pretest probability, 24.1%); and F4, 4.45 kPa (pretest probability, 8.7%). In generalized linear mixed model analysis, histological steatohepatitis with higher inflammatory activity (odds ratio 2.448, 95% CI 1.180–5.079, p <0.05) and high gamma-glutamyl transferase (GGT) concentration (>120U/L) (odds ratio 3.388, 95% CI 1.577–7.278, p <0.01] were significantly associated with elevated liver stiffness, and thus affecting accuracy in staging early fibrosis (F0–F1). Steatosis, as measured by magnetic resonance imaging proton density fat fraction, and body mass index(BMI) were not confounders.
Conclusions: MRE has excellent diagnostic performance for significant, advanced fibrosis and cirrhosis in patients with NAFLD. Elevated inflammatory activity and GGT level may lead to overestimation of early liver fibrosis, but anthropometric measures such as BMI or the degree of steatosis do not.

Journal article: Mózes, F.E. et al, “Performance of non-invasive tests and histology for the prediction of clinical outcomes in patients with non-alcoholic fatty liver disease: an individual participant data meta-analysis”, Lancet Gastroenterology & Hepatology 8(8), August 2023

Abstract
Background: Histologically assessed liver fibrosis stage has prognostic significance in patients with non-alcoholic fatty liver disease (NAFLD) and is accepted as a surrogate endpoint in clinical trials for non-cirrhotic NAFLD. Our aim was to compare the prognostic performance of non-invasive tests with liver histology in patients with NAFLD.
Methods: This was an individual participant data meta-analysis of the prognostic performance of histologically assessed fibrosis stage (F0–4), liver stiffness measured by vibration-controlled transient elastography (LSM-VCTE), fibrosis-4 index (FIB-4), and NAFLD fibrosis score (NFS) in patients with NAFLD. The literature was searched for a previously published systematic review on the diagnostic accuracy of imaging and simple non-invasive tests and updated to Jan 12, 2022 for this study. Studies were identified through PubMed/MEDLINE, EMBASE, and CENTRAL, and authors were contacted for individual participant data, including outcome data, with a minimum of 12 months of follow-up. The primary outcome was a composite endpoint of all-cause mortality, hepatocellular carcinoma, liver transplantation, or cirrhosis complications (ie, ascites, variceal bleeding, hepatic encephalopathy, or progression to a MELD score ≥15). We calculated aggregated survival curves for trichotomised groups and compared them using stratified log-rank tests (histology: F0–2 vs F3 vs F4; LSM: <10 vs 10 to <20 vs ≥20 kPa; FIB-4: <1·3 vs 1·3 to ≤2·67 vs >2·67; NFS: <–1·455 vs –1·455 to ≤0·676 vs >0·676), calculated areas under the time-dependent receiver operating characteristic curves (tAUC), and performed Cox proportional-hazards regression to adjust for confounding. This study was registered with PROSPERO, CRD42022312226.
Findings: Of 65 eligible studies, we included data on 2518 patients with biopsy-proven NAFLD from 25 studies (1126 [44·7%] were female, median age was 54 years [IQR 44–63), and 1161 [46·1%] had type 2 diabetes). After a median follow-up of 57 months [IQR 33–91], the composite endpoint was observed in 145 (5·8%) patients. Stratified log-rank tests showed significant differences between the trichotomised patient groups (p<0·0001 for all comparisons). The tAUC at 5 years were 0·72 (95% CI 0·62–0·81) for histology, 0·76 (0·70–0·83) for LSM-VCTE, 0·74 (0·64–0·82) for FIB-4, and 0·70 (0·63–0·80) for NFS. All index tests were significant predictors of the primary outcome after adjustment for confounders in the Cox regression.
Interpretation: Simple non-invasive tests performed as well as histologically assessed fibrosis in predicting clinical outcomes in patients with NAFLD and could be considered as alternatives to liver biopsy in some cases.

Journal article: Pennisi, G. et al, “Noninvasive assessment of liver disease severity in patients with nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes”, Hepatology 78(1), July 2023

Abstract
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.

Journal article: Lee, J. et al, “Machine learning algorithm improves detection of NASH (NAS-based) and at-risk NASH, a development and validation study”, Hepatology 78(1), July 2023

Abstract
Background and Aims: Detecting NASH remains challenging, while at-risk NASH (steatohepatitis and F≥ 2) tends to progress and is of interest for drug development and clinical application. We developed prediction models by supervised machine learning techniques, with clinical data and biomarkers to stage and grade patients with NAFLD.
Approach and Results: Learning data were collected in the Liver Investigation: Testing Marker Utility in Steatohepatitis metacohort (966 biopsy-proven NAFLD adults), staged and graded according to NASH CRN. Conditions of interest were the clinical trial definition of NASH (NAS ≥ 4;53%), at-risk NASH (NASH with F ≥ 2;35%), significant (F ≥ 2;47%), and advanced fibrosis (F ≥ 3;28%). Thirty-five predictors were included. Missing data were handled by multiple imputations. Data were randomly split into training/validation (75/25) sets. A gradient boosting machine was applied to develop 2 models for each condition: clinical versus extended (clinical and biomarkers). Two variants of the NASH and at-risk NASH models were constructed: direct and composite models.
Clinical gradient boosting machine models for steatosis/inflammation/ballooning had AUCs of 0.94/0.79/0.72. There were no improvements when biomarkers were included. The direct NASH model produced AUCs (clinical/extended) of 0.61/0.65. The composite NASH model performed significantly better (0.71) for both variants. The composite at-risk NASH model had an AUC of 0.83 (clinical and extended), an improvement over the direct model. Significant fibrosis models had AUCs (clinical/extended) of 0.76/0.78. The extended advanced fibrosis model (0.86) performed significantly better than the clinical version (0.82).
Conclusions: Detection of NASH and at-risk NASH can be improved by constructing independent machine learning models for each component, using only clinical predictors. Adding biomarkers only improved the accuracy of fibrosis.

Journal article: Rasmussen, D.G.K. et al, “NALFD and NASH Biomarker Qualification in the LITMUS consortium – Lessons learned”, Journal of Hepatology 78(4), April 2023

Abstract
Biomarkers have the potential to accelerate drug development, as early indicators of improved clinical response, to improve patient safety, and for personalised medicine. However, few have been approved through the biomarker qualification pathways of the regulatory agencies. This paper outlines how biomarkers can accelerate drug development, and reviews the lessons learned by the EU IMI2-funded LITMUS consortium, which has had several interactions with regulatory agencies in both the US and EU regarding biomarker qualification in patients with non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. Sharing knowledge of such interactions with the scientific community is of paramount importance to increase the chances of qualification of relevant biomarkers that may accelerate drug development, and thereby help patients, across disease indications. A qualified biomarker enables a decision to be made that all understand and support in a common framework.

Journal article: Govaere, O. et al, “A proteo-transcriptomic map of non-alcoholic fatty liver disease signatures”, Nature Metabolism 5, 10^th April 2023.

Abstract
Non-alcoholic fatty liver disease (NAFLD) is a common, progressive liver disease strongly associated with the metabolic syndrome. It is unclear how progression of NAFLD towards cirrhosis translates into systematic changes in circulating proteins. Here, we provide a detailed proteo-transcriptomic map of steatohepatitis and fibrosis during progressive NAFLD. In this multicentre proteomic study, we characterize 4,730 circulating proteins in 306 patients with histologically characterized NAFLD and integrate this with transcriptomic analysis in paired liver tissue. We identify circulating proteomic signatures for active steatohepatitis and advanced fibrosis, and correlate these with hepatic transcriptomics to develop a proteo-transcriptomic signature of 31 markers. Deconvolution of this signature by single-cell RNA sequencing reveals the hepatic cell types likely to contribute to proteomic changes with disease progression. As an exemplar of use as a non-invasive diagnostic, logistic regression establishes a composite model comprising four proteins (ADAMTSL2, AKR1B10, CFHR4 and TREM2), body mass index and type 2 diabetes mellitus status, to identify at-risk steatohepatitis.

Journal article: Vali, Y. et al, “Biomarkers for staging fibrosis and non-alcoholic steatohepatitis in non-alcoholic fatty liver disease (the LITMUS project): a comparative diagnostic accuracy study”, Lancet Gastroenterology & Hepatology, 20^th March 2023.

Abstract
Background: The reference standard for detecting non-alcoholic steatohepatitis (NASH) and staging fibrosis—liver biopsy—is invasive and resource intensive. Non-invasive biomarkers are urgently needed, but few studies have compared these biomarkers in a single cohort. As part of the Liver Investigation: Testing Marker Utility in Steatohepatitis (LITMUS) project, we aimed to evaluate the diagnostic accuracy of 17 biomarkers and multimarker scores in detecting NASH and clinically significant fibrosis in patients with non-alcoholic fatty liver disease (NAFLD) and identify their optimal cutoffs as screening tests in clinical trial recruitment.
Methods: This was a comparative diagnostic accuracy study in people with biopsy-confirmed NAFLD from 13 countries across Europe, recruited between Jan 6, 2010, and Dec 29, 2017, from the LITMUS metacohort of the prospective European NAFLD Registry. Adults (aged ≥18 years) with paired liver biopsy and serum samples were eligible; those with excessive alcohol consumption or evidence of other chronic liver diseases were excluded. The diagnostic accuracy of the biomarkers was expressed as the area under the receiver operating characteristic curve (AUC) with liver histology as the reference standard and compared with the Fibrosis-4 index for liver fibrosis (FIB-4) in the same subgroup. Target conditions were the presence of NASH with clinically significant fibrosis (ie, at-risk NASH; NAFLD Activity Score ≥4 and F≥2) or the presence of advanced fibrosis (F≥3), analysed in all participants with complete data. We identified thres holds for each biomarker for reducing the number of biopsy-based screen failures when recruiting people with both NASH and clinically significant fibrosis for future trials.
Findings: Of 1430 participants with NAFLD in the LITMUS metacohort with serum samples, 966 (403 women and 563 men) were included after all exclusion criteria had been applied. 335 (35%) of 966 participants had biopsy-confirmed NASH and clinically significant fibrosis and 271 (28%) had advanced fibrosis. For people with NASH and clinically significant fibrosis, no single biomarker or multimarker score significantly reached the predefined AUC 0·80 acceptability threshold (AUCs ranging from 0·61 [95% CI 0·54–0·67] for FibroScan controlled attenuation parameter to 0·81 [0·75–0·86] for SomaSignal), with accuracy mostly similar to FIB-4. Regarding detection of advanced fibrosis, SomaSignal (AUC 0·90 [95% CI 0·86–0·94]), ADAPT (0·85 [0·81–0·89]), and FibroScan liver stiffness measurement (0·83 [0·80–0·86]) reached acceptable accuracy. With 11 of 17 markers, histological screen failure rates could be reduced to 33% in trials if only people who were marker positive had a biopsy for evaluating eligibility. The best screening performance for NASH and clinically significant fibrosis was observed for SomaSignal (number needed to test [NNT] to find one true positive was four [95% CI 4–5]), then ADAPT (six [5–7]), MACK-3 (seven [6–8]), and PRO-C3 (nine [7–11]).
Interpretation: None of the single markers or multimarker scores achieved the predefined acceptable AUC for replacing biopsy in detecting people with both NASH and clinically significant fibrosis. However, several biomarkers could be applied in a prescreening strategy in clinical trial recruitment. The performance of promising markers will be further evaluated in the ongoing prospective LITMUS study cohort.

Journal article: Tamaki, N. et al, “Risk of advanced fibrosis in first-degree relatives of patients with nonalcoholic fatty liver disease”, Journal of Clinical Investigation 132(21), 1^st November 2022.

Abstract
Background: A pilot, single-center study showed that first-degree relatives of probands with nonalcoholic fatty liver disease (NAFLD) cirrhosis have a high risk of advanced fibrosis. We aimed to validate these findings using 2 independent cohorts from the US and Europe.
Methods: This prospective study included probands with NAFLD with advanced fibrosis, NAFLD without advanced fibrosis, and non-NAFLD, with at least 1 first-degree relative. A total of 396 first-degree relatives — 220 in a derivation cohort and 176 in a validation cohort — were enrolled in the study, and liver fibrosis was evaluated using magnetic resonance elastography and other noninvasive imaging modalities. The primary outcome was prevalence of advanced fibrosis in first-degree relatives.
Results: Prevalence of advanced fibrosis in first-degree relatives of probands with NAFLD with advanced fibrosis, NAFLD without advanced fibrosis, and non-NAFLD was 15.6%, 5.9%, and 1.3%, respectively (P = 0.002), in the derivation cohort, and 14.0%, 2.6%, and 1.3%, respectively (P = 0.004), in the validation cohort. In multivariable-adjusted logistic regression models, age of ≥50 years (adjusted OR [aOR]: 2.63, 95% CI 1.0–6.7), male sex (aOR: 3.79, 95% CI 1.6–9.2), diabetes mellitus (aOR: 3.37, 95% CI 1.3–9), and a first-degree relative with NAFLD with advanced fibrosis (aOR: 11.8, 95% CI 2.5–57) were significant predictors of presence of advanced fibrosis (all P < 0.05).
Conclusion: First-degree relatives of probands with NAFLD with advanced fibrosis have significantly increased risk of advanced fibrosis. Routine screening should be done in the first-degree relatives of patients with advanced fibrosis.

Journal article: Gil-Gómez, A. et al, “Impact of a Loss-of-Function Variant in HSD17B13 on Hepatic Decompensation and Mortality in Cirrhotic Patients”, International Journal of Molecular Sciences 23(19), 6^th October 2022.

Abstract
A common splice variant in HSD17B13 (rs72613567:TA) was recently found to be associated with a reduced risk of developing chronic liver disease in NAFLD patients and a reduced risk of progression to advanced fibrosis and cirrhosis. In this study, we aimed to evaluate the prognosis of cirrhotic patients harboring this variant. We performed a retrospective analysis on 483 prospectively recruited patients from four different hospitals in Spain, followed-up for at least 5 years. We collected clinical, demographic, and biochemical data, and we performed a genotyping analysis for common variants previously associated with liver disease risk (HSD17B13 rs72613567:TA and PNPLA3 rs738409). Patients homozygous for the TA allele showed a higher MELD score (p = 0.047), Child–Turcotte–Pugh score (p = 0.014), and INR levels (p = 0.046), as well as decreased albumin (p = 0.004) at baseline. After multivariate analysis, patients with the “protective” variant indeed had an increased risk of hepatic decompensation [aHR 2.37 (1.09–5.06); p = 0.029] and liver-related mortality [aHR 2.32 (1.20–4.46); p = 0.012]. Specifically, these patients had an increased risk of developing ascites (Log-R 11.6; p < 0.001), hepatic encephalopathy (Log-R 10.2; p < 0.01), and higher mortality (Log-R 14.1; p < 0.001) at 5 years of follow-up. Interactions with the etiology of the cirrhosis and with the variant rs738409 in PNPLA3 are also described. These findings suggest that the variant rs72613567:TA in HSD17B13 has no protective effect, but indeed increases the risk of decompensation and death in patients with advanced chronic liver disease.

Journal article: Martínez-Arranz, I. et al, “Metabolic subtypes of patients with NAFLD exhibit distinctive cardiovascular risk profiles”, Hepatology 76(4), 1^st October 2022.

Abstract
Background and Aims: We previously identified subsets of patients with NAFLD with different metabolic phenotypes. Here we align metabolomic signatures with cardiovascular disease (CVD) and genetic risk factors.
Approach and Results: We analyzed serum metabolome from 1154 individuals with biopsy-proven NAFLD, and from four mouse models of NAFLD with impaired VLDL-triglyceride (TG) secretion, and one with normal VLDL-TG secretion. We identified three metabolic subtypes: A (47%), B (27%), and C (26%). Subtype A phenocopied the metabolome of mice with impaired VLDL-TG secretion; subtype C phenocopied the metabolome of mice with normal VLDL-TG; and subtype B showed an intermediate signature. The percent of patients with NASH and fibrosis was comparable among subtypes, although subtypes B and C exhibited higher liver enzymes. Serum VLDL-TG levels and secretion rate were lower among subtype A compared with subtypes B and C. Subtype A VLDL-TG and VLDL–apolipoprotein B concentrations were independent of steatosis, whereas subtypes B and C showed an association with these parameters. Serum TG, cholesterol, VLDL, small dense LDL, and remnant lipoprotein cholesterol were lower among subtype A compared with subtypes B and C. The 10-year high risk of CVD, measured with the Framingham risk score, and the frequency of patatin-like phospholipase domain-containing protein 3 NAFLD risk allele were lower in subtype A.
Conclusions: Metabolomic signatures identify three NAFLD subgroups, independent of histological disease severity. These signatures align with known CVD and genetic risk factors, with subtype A exhibiting a lower CVD risk profile. This may account for the variation in hepatic versus cardiovascular outcomes, offering clinically relevant risk stratification.

Journal article: Vali, Y. et al, “Clinicians’ Perspectives on Barriers and Facilitators for the Adoption of Non-Invasive Liver Tests for NAFLD: A Mixed-Method Study”, Journal of Clinical Medicine 11(10), 11^th May 2022.

Abstract
(1) Background: Given the high prevalence of non-alcoholic fatty liver disease (NAFLD) and the limitations of liver biopsies, multiple non-invasive tests (NITs) have been developed to identify non-alcoholic fatty liver disease (NAFLD) patients at-risk of progression. The availability of these new NITs varies from country to country, and little is known about their implementation and adoption in routine clinical practice. This study aims to explore barriers and facilitators that influence the adoption of NAFLD NITs, from healthcare professionals’ perspectives.
(2) Methods: A cross-sectional study was performed using an exploratory mixed-methods approach. Twenty-seven clinicians from eight different countries with different specialties filled in our questionnaire. Of those, 16 participated in semi-structured interviews. Qualitative and quantitative data were collected and summarized using the recently published Non-adoption, Abandonment, Scale-up, Spread, and Sustainability (NASSS) framework for new medical technologies in healthcare organizations.
(3) Results: Several factors were reported as influencing the uptake of NITs for NAFLD in clinical practice. Among those: insufficient awareness of tests; lack of practical guidelines and evidence for the performance of tests in appropriate patient populations and care settings; and absence of sufficient reimbursement systems were reported as the most important barriers. Other factors, most notably ‘local champions’, proper functional payment systems, and sufficient resources in academic hospitals, were indicated as important facilitating factors.
(4) Conclusions: Clinicians see the adoption of NITs for NAFLD as a complex process that is modulated by several factors, such as robust evidence, practical guidelines, a proper payment system, and local champions. Future research could explore perspectives from other stakeholders on the adoption of NITs.

Journal article: Labenz, C. et al, “Derivation and validation of the nonalcoholic fatty liver disease cirrhosis score (NCS) to distinguish bridging fibrosis from cirrhosis”, European Journal of Internal Medicine 98, 1^st April 2022.

Abstract
Separation of bridging fibrosis from cirrhosis in non-alcoholic fatty liver disease (NAFLD) is critical to guide management. Therefore, it was the aim of this study to develop an easy-to-perform score distinguishing F3 and F4 fibrosis in NAFLD. A derivation cohort comprising 251 NAFLD patients with F3 or F4 was used to develop the NAFLD Cirrhosis Score (NCS). The NCS was validated in three independent cohorts with liver histology comprising 1666 participants from the STELLAR trials, 47 patients from China and 2058 patients from the European NAFLD Registry. A model including INR, gGT, ALT, platelets and age discriminated best between patients with bridging fibrosis and cirrhosis with an area under the curve (AUC) of 0.733 (95%CI 0.671–0.795). The diagnostic performance of the NCS was similar in the STELLAR studies (AUC 0.700; 95%CI 0.680–0.730) and a smaller cohort from China (AUC 0.727; 95%CI 0.533–0.921). In the European NAFLD Registry, spanning all histological fibrosis stages, the NCS exhibited an AUC of 0.798 (95%CI 0.766–0.830) to detect cirrhosis. We derived two NCS cut-off values (<64.5 and >79.17) to classify patients at low, intermediate, or high risk for the presence of cirrhosis. Using these cut-offs, further diagnostic workup could be avoided by ruling in or ruling out cirrhosis in approximately half of the patients. Furthermore, NCS identified patients at risk for progression to cirrhosis in the F3 cohort and liver-related outcomes in the F4 cohort.
Conclusion:
The NCS is a simple tool to improve the identification of compensated cirrhosis within the large group of advanced disease stage and provides prognostic information. Overall, the differentiation of F3 from F4 disease using standard laboratory remains difficult and does not exceed moderate accuracy.

Editorial: Schuppan, D., Myneni, S. & Surabattula, R., “Liquid biomarkers for fibrotic NASH – progress in a complex field”, Journal of Hepatology 76(1), 1^st January 2022.

Journal article: Sen, P. et al, “Quantitative modelling of human liver reveals dysregulation of glycosphingolipid pathways in nonalcoholic fatty liver disease”, iScience 25(9), 16^th September 2022.
Abstract
Non-alcoholic fatty liver disease (NAFLD) is an increasingly prevalent disease that is associated with multiple metabolic disturbances, yet the metabolic pathways underlying its progression are poorly understood. Here, we studied metabolic pathways of the human liver across the full histological spectrum of NAFLD. We analyzed whole liver tissue transcriptomics and serum metabolomics data obtained from a large, prospectively enrolled cohort of 206 histologically characterized patients derived from the European NAFLD Registry and developed genome-scale metabolic models (GEMs) of human hepatocytes at different stages of NAFLD. We identified several metabolic signatures in the liver and blood of these patients, specifically highlighting the alteration of vitamins (A, E) and glycosphingolipids, and their link with complex glycosaminoglycans in advanced fibrosis. Furthermore, we derived GEMs and identified metabolic signatures of three common NAFLD-associated gene variants (PNPLA3, TM6SF2, and HSD17B13). The study demonstrates dysregulated liver metabolic pathways which may contribute to the progression of NAFLD.

Journal article: Brunt, E.M. et al, “Complexity of Ballooned Hepatocyte Feature Recognition: Defining a Training Atlas for Imaging-Based Artificial Intelligence in NAFLD”, Journal of Hepatology 76(5), 1^st May 2022.
Abstract
Background & Aims:
Histologically assessed hepatocyte ballooning is a key feature discriminating non-alcoholic steatohepatitis (NASH) from steatosis (NAFL). Reliable identification underpins patient inclusion in clinical trials and serves as a key regulatory-approved surrogate endpoint for drug efficacy. High inter/intra-observer variation in ballooning measured using the NASH CRN semi-quantitative score has been reported yet no actionable solutions have been proposed.
Methods:
A focused evaluation of hepatocyte ballooning recognition was conducted. Digitized slides were evaluated by 9 internationally recognized expert liver pathologists on 2 separate occasions: each pathologist independently marked every ballooned hepatocyte and later provided an overall non-NASH NAFL/NASH assessment. Interobserver variation was assessed and a ‘concordance atlas’ of ballooned hepatocytes generated to train second harmonic generation/two-photon excitation fluorescence imaging-based artificial intelligence (AI).
Results:
The Fleiss kappa statistic for overall interobserver agreement for presence/absence of ballooning was 0.197 (95% CI 0.094–0.300), rising to 0.362 (0.258–0.465) with a ≥5-cell threshold. However, the intraclass correlation coefficient for consistency was higher (0.718 [0.511–0.900]), indicating ‘moderate’ agreement on ballooning burden. 133 ballooned cells were identified using a ≥5/9 majority to train AI ballooning detection (AI-pathologist pairwise concordance 19–42%, comparable to inter-pathologist pairwise concordance of between 8–75%). AI quantified change in ballooned cell burden in response to therapy in a separate slide set.
Conclusions:
The substantial divergence in hepatocyte ballooning identified amongst expert hepatopathologists suggests that ballooning is a spectrum, too subjective for its presence or complete absence to be unequivocally determined as a trial endpoint. A concordance atlas may be used to train AI assistive technologies to reproducibly quantify ballooned hepatocytes that standardize assessment of therapeutic efficacy. This atlas serves as a reference standard for ongoing work to refine how ballooning is classified by both pathologists and AI.

Journal article: Govaere, O. et al, “Macrophage Scavenger Receptor 1 mediates lipid-induced inflammation in non-alcoholic fatty liver disease”, Journal of Hepatology 76(5), 1^st May 2022.
Abstract
Background & Aims:
Obesity-associated inflammation is a key player in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the role of macrophage scavenger receptor 1 (MSR1, CD204) remains incompletely understood.
Methods:
A total of 170 NAFLD liver biopsies were processed for transcriptomic analysis and correlated with clinicopathological features. Msr1^-/- and wild-type mice were subjected to a 16-week high-fat and high-cholesterol diet. Mice and ex vivo human liver slices were treated with a monoclonal antibody against MSR1. Genetic susceptibility was assessed using genome-wide association study data from 1,483 patients with NAFLD and 430,101 participants of the UK Biobank.
Results:
MSR1 expression was associated with the occurrence of hepatic lipid-laden foamy macrophages and correlated with the degree of steatosis and steatohepatitis in patients with NAFLD. Mice lacking Msr1 were protected against diet-induced metabolic disorder, showing fewer hepatic foamy macrophages, less hepatic inflammation, improved dyslipidaemia and glucose tolerance, and altered hepatic lipid metabolism. Upon induction by saturated fatty acids, MSR1 induced a pro-inflammatory response via the JNK signalling pathway. In vitro blockade of the receptor prevented the accumulation of lipids in primary macrophages which inhibited the switch towards a pro-inflammatory phenotype and the release of cytokines such as TNF-ɑ. Targeting MSR1 using monoclonal antibody therapy in an obesity-associated NAFLD mouse model and human liver slices resulted in the prevention of foamy macrophage formation and inflammation. Moreover, we identified that rs41505344, a polymorphism in the upstream transcriptional region of MSR1, was associated with altered serum triglycerides and aspartate aminotransferase levels in a cohort of over 400,000 patients.
Conclusions:
Taken together, our data suggest that MSR1 plays a critical role in lipid-induced inflammation and could thus be a potential therapeutic target for the treatment of NAFLD.

Journal article: Mózes, F.E. et al, “Diagnostic accuracy of non-invasive tests for advanced fibrosis in patients with NAFLD: an individual patient data meta-analysis”, Gut 71(5), 1^st May 2022.
Abstract
Objective:
Liver biopsy is still needed for fibrosis staging in many patients with non-alcoholic fatty liver disease. The aims of this study were to evaluate the individual diagnostic performance of liver stiffness measurement by vibration controlled transient elastography (LSM-VCTE), Fibrosis-4 Index (FIB-4) and NAFLD (non-alcoholic fatty liver disease) Fibrosis Score (NFS) and to derive diagnostic strategies that could reduce the need for liver biopsies.
Design:
Individual patient data meta-analysis of studies evaluating LSM-VCTE against liver histology was conducted. FIB-4 and NFS were computed where possible. Sensitivity, specificity and area under the receiver operating curve (AUROC) were calculated. Biomarkers were assessed individually and in sequential combinations.
Results:
Data were included from 37 primary studies (n=5735; 45% women; median age: 54 years; median body mass index: 30 kg/m2; 33% had type 2 diabetes; 30% had advanced fibrosis). AUROCs of individual LSM-VCTE, FIB-4 and NFS for advanced fibrosis were 0.85, 0.76 and 0.73. Sequential combination of FIB-4 cut-offs (<1.3; ≥2.67) followed by LSM-VCTE cut-offs (<8.0; ≥10.0 kPa) to rule-in or rule-out advanced fibrosis had sensitivity and specificity (95% CI) of 66% (63–68) and 86% (84–87) with 33% needing a biopsy to establish a final diagnosis. FIB-4 cut-offs (<1.3; ≥3.48) followed by LSM cut-offs (<8.0; ≥20.0 kPa) to rule out advanced fibrosis or rule in cirrhosis had a sensitivity of 38% (37–39) and specificity of 90% (89–91) with 19% needing biopsy.
Conclusion:
Sequential combinations of markers with a lower cut-off to rule-out advanced fibrosis and a higher cut-off to rule-in cirrhosis can reduce the need for liver biopsies.

Journal article: McGlinchey, A.J. et al, “Metabolic signatures across the full spectrum of nonalcoholic fatty liver disease”, JHEP Reports 4(5), 1^st May 2022.
Abstract
Background & Aims:
Non-alcoholic fatty liver disease (NAFLD) is a progressive liver disease with potentially severe complications including cirrhosis and hepatocellular carcinoma. Previously, we have identified circulating lipid signatures associating with liver fat content and non-alcoholic steatohepatitis (NASH). Here, we develop a metabolomic map across the NAFLD spectrum, defining interconnected metabolic signatures of steatosis (non-alcoholic fatty liver, NASH, and fibrosis).
Methods:
We performed mass spectrometry analysis of molecular lipids and polar metabolites in serum samples from the European NAFLD Registry patients (n = 627), representing the full spectrum of NAFLD. Using various univariate, multivariate, and machine learning statistical approaches, we interrogated metabolites across 3 clinical perspectives: steatosis, NASH, and fibrosis.
Results:
Following generation of the NAFLD metabolic network, we identify 15 metabolites unique to steatosis, 18 to NASH, and 15 to fibrosis, with 27 common to all. We identified that progression from F2 to F3 fibrosis coincides with a key pathophysiological transition point in disease natural history, with n = 73 metabolites altered.
Conclusions:
Analysis of circulating metabolites provides important insights into the metabolic changes during NAFLD progression, revealing metabolic signatures across the NAFLD spectrum and features that are specific to NAFL, NASH, and fibrosis. The F2–F3 transition marks a critical metabolic transition point in NAFLD pathogenesis, with the data pointing to the pathophysiological importance of metabolic stress and specifically oxidative stress.

Journal article: Johnson, K. et al, “Increased serum miR-193a-5p during non-alcoholic fatty liver disease progression: diagnostic and mechanistic relevance”, JHEP Reports 4(2), 1^st February 2022.
Abstract
Background & Aims:
Serum microRNA (miRNA) levels are known to change in non-alcoholic fatty liver disease (NAFLD) and may serve as useful biomarkers. This study aimed to profile miRNAs comprehensively at all NAFLD stages.
Methods:
We profiled 2,083 serum miRNAs in a discovery cohort (183 cases with NAFLD representing the complete NAFLD spectrum and 10 population controls). miRNA libraries generated by HTG EdgeSeq were sequenced by Illumina NextSeq. Selected serum miRNAs were profiled in 372 additional cases with NAFLD and 15 population controls by quantitative reverse transcriptase PCR.
Results:
Levels of 275 miRNAs differed between cases and population controls. Fewer differences were seen within individual NAFLD stages, but miR-193a-5p consistently showed increased levels in all comparisons. Relative to NAFL/non-alcoholic steatohepatitis (NASH) with mild fibrosis (stage 0/1), 3 miRNAs (miR-193a-5p, miR-378d, and miR378d) were increased in cases with NASH and clinically significant fibrosis (stages 2–4), 7 (miR193a-5p, miR-378d, miR-378e, miR-320b, miR-320c, miR-320d, and miR-320e) increased in cases with NAFLD activity score (NAS) 5–8 compared with lower NAS, and 3 (miR-193a-5p, miR-378d, and miR-378e) increased but 1 (miR-19b-3p) decreased in steatosis, activity, and fibrosis (SAF) activity score 2–4 compared with lower SAF activity. The significant findings for miR-193a-5p were replicated in the additional cohort with NAFLD. Studies in Hep G2 cells showed that following palmitic acid treatment, miR-193a-5p expression decreased significantly. Gene targets for miR-193a-5p were investigated in liver RNAseq data for a case subgroup (n = 80); liver GPX8 levels correlated positively with serum miR-193a-5p.
Conclusions:
Serum miR-193a-5p levels correlate strongly with NAFLD activity grade and fibrosis stage. MiR-193a-5p may have a role in the hepatic response to oxidative stress and is a potential clinically tractable circulating biomarker for progressive NAFLD.

Journal article: Mak, A.L. et al, “Systematic Review with Meta-Analysis: Diagnostic Accuracy of Pro-C3 for Hepatic Fibrosis in Patients with Non-Alcoholic Fatty Liver Disease”, Biomedicines 9(12), 15^th December 2021.
Abstract
The prevalence and severity of non-alcoholic fatty liver disease (NAFLD) is increasing, yet adequately validated tests for care paths are limited and non-invasive markers of disease progression are urgently needed. The aim of this work was to summarize the performance of Pro-C3, a biomarker of active fibrogenesis, in detecting significant fibrosis (F ≥ 2), advanced fibrosis (F ≥ 3), cirrhosis (F4) and non-alcoholic steatohepatitis (NASH) in patients with NAFLD. A sensitive search of five databases was performed in July 2021. Studies reporting Pro-C3 measurements and liver histology in adults with NAFLD without co-existing liver diseases were eligible. Meta-analysis was conducted by applying a bivariate random effects model to produce summary estimates of Pro-C3 accuracy. From 35 evaluated reports, eight studies met our inclusion criteria; 1568 patients were included in our meta-analysis of significant fibrosis and 2058 in that of advanced fibrosis. The area under the summary curve was 0.81 (95% CI 0.77–0.84) in detecting significant fibrosis and 0.79 (95% CI 0.73–0.82) for advanced fibrosis. Our results support Pro-C3 as an important candidate biomarker for non-invasive assessment of liver fibrosis in NAFLD. Further direct comparisons with currently recommended non-invasive tests will demonstrate whether Pro-C3 panels can outperform these tests, and improve care paths for patients with NAFLD.

Journal article: Selvaraj, E.A. et al, “Diagnostic accuracy of elastography and magnetic resonance imaging in patients with NAFLD: a systematic review and meta-analysis”, Journal of Hepatology 75(4), 1^st October 2021.
Abstract
Background and Aims:
Vibration-controlled transient elastography (VCTE), point shear wave elastography (pSWE), 2-dimensional shear wave elastography (2DSWE), magnetic resonance elastography (MRE), and magnetic resonance imaging (MRI) have been proposed as non-invasive tests for patients with non-alcoholic fatty liver disease (NAFLD). This study evaluated their diagnostic accuracy for liver fibrosis and non-alcoholic steatohepatitis (NASH).
Methods:
PubMED/MEDLINE, EMBASE and the Cochrane Library were searched for studies examining the diagnostic accuracy of these index tests, against histology as the reference standard, in adult patients with NAFLD. Two authors independently screened and assessed methodological quality of studies and extracted data. Summary estimates of sensitivity, specificity and area under the curve (sAUC) were calculated for fibrosis stages and NASH, using a random effects bivariate logit-normal model.
Results:
We included 82 studies (14,609 patients). Meta-analysis for diagnosing fibrosis stages was possible in 53 VCTE, 11 MRE, 12 pSWE and 4 2DSWE studies, and for diagnosing NASH in 4 MRE studies. sAUC for diagnosis of significant fibrosis were: 0.83 for VCTE, 0.91 for MRE, 0.86 for pSWE and 0.75 for 2DSWE. sAUC for diagnosis of advanced fibrosis were: 0.85 for VCTE, 0.92 for MRE, 0.89 for pSWE and 0.72 for 2DSWE. sAUC for diagnosis of cirrhosis were: 0.89 for VCTE, 0.90 for MRE, 0.90 for pSWE and 0.88 for 2DSWE. MRE had sAUC of 0.83 for diagnosis of NASH. Three (4%) studies reported intention-to-diagnose analyses and 15 (18%) studies reported diagnostic accuracy against pre-specified cut-offs.
Conclusions:
When elastography index tests are acquired successfully, they have acceptable diagnostic accuracy for advanced fibrosis and cirrhosis. The potential clinical impact of these index tests cannot be assessed fully as intention-to-diagnose analyses and validation of pre-specified thresholds are lacking.

Journal article: Masoodi, M. et al, “Metabolomics and lipidomics in NAFLD: biomarkers and non-invasive diagnostic tests”, Nature Reviews Gasteroenterology & Hepatology, 10^th September 2021.
Abstract
Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide and is often associated with aspects of metabolic syndrome. Despite its prevalence and the importance of early diagnosis, there is a lack of robustly validated biomarkers for diagnosis, prognosis and monitoring of disease progression in response to a given treatment. In this Review, we provide an overview of the contribution of metabolomics and lipidomics in clinical studies to identify biomarkers associated with NAFLD and nonalcoholic steatohepatitis (NASH). In addition, we highlight the key metabolic pathways in NAFLD and NASH that have been identified by metabolomics and lipidomics approaches and could potentially be used as biomarkers for non-invasive diagnostic tests. Overall, the studies demonstrated alterations in amino acid metabolism and several aspects of lipid metabolism including circulating fatty acids, triglycerides, phospholipids and bile acids. Although we report several studies that identified potential biomarkers, few have been validated.

Journal article: Geier, A. et al, “From the origin of NASH to the future of metabolic fatty liver disease”, Gut 70(8), August 2021.
Abstract
Non-alcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease worldwide. Understanding the pathological and molecular hallmarks from its first description to definitions of disease entities, classifications and molecular phenotypes is crucial for both appropriate clinical management and research in this complex disease. We provide an overview through almost two hundred years of clinical research from the beginnings as a nebulous disease entity of unknown origin in the 19th century to the most frequent and vigorously investigated liver disease today. The clinical discrimination between alcohol-related liver disease and NAFLD was uncommon until the 1950s and likely contributed to the late acceptance of NAFLD as a metabolic disease entity for long time. Although the term ‘fatty liver hepatitis’ first appeared in 1962, it was in 1980 that the term ‘non-alcoholic steatohepatitis’ (NASH) was coined and the histopathological hallmarks that are still valid today were defined. The 2005 NASH Clinical Research Network scoring was the first globally accepted grading and staging system for the full spectrum of NAFLD and is still used to semiquantify main histological features. In 2021, liver biopsy remains the only diagnostic procedure that can reliably assess the presence of NASH and early fibrosis but increasing efforts are made towards non-invasive testing and molecular classification of NAFLD subtypes.

Journal article: van Dijk, A-M. et al, “Systematic Review with Meta-Analyses: Diagnostic Accuracy of FibroMeter Tests in Patients with Non-Alcoholic Fatty Liver Disease”, Journal of Clinical Medicine 10(13), 29^th June 2021.
Abstract

Early detection of liver fibrosis is crucial to select the correct care path for patients with non-alcoholic fatty liver disease (NAFLD). Here, we systematically review the evidence on the performance of FibroMeter versions in detecting different levels of fibrosis in patients with NAFLD. We searched four databases (Medline, Embase, the Cochrane library, and Web of Science) to find studies that included adults with NAFLD and biopsy-confirmed fibrosis (F1 to F4), compared with any version of FibroMeter. Two independent researchers screened the references, collected the data, and assessed the methodological quality of the included studies. We used a bivariate logit-normal random effects model to produce meta-analyses. From 273 references, 12 studies were eligible for inclusion, encompassing data from 3425 patients. Meta-analyses of the accuracy in detecting advanced fibrosis (F ≥ 3) were conducted for FibroMeter Virus second generation (V2G), NAFLD, and vibration controlled transient elaFS3stography (VCTE). FibroMeter VCTE showed the best diagnostic accuracy in detecting advanced fibrosis (sensitivity: 83.5% (95%CI 0.58–0.94); specificity: 91.1% (95%CI 0.89–0.93)), followed by FibroMeter V2G (sensitivity: 83.1% (95%CI 0.73–0.90); specificity: 84.4% (95%CI 0.62–0.95)) and FibroMeter NAFLD (sensitivity: 71.7% (95%CI 0.63–0.79); specificity: 82.8% (95%CI 0.71–0.91)). No statistically significant differences were found between the different FibroMeter versions. FibroMeter tests showed acceptable sensitivity and specificity in detecting advanced fibrosis in patients with NAFLD, but an urge to conduct head-to-head comparison studies in patients with NAFLD of the different FibroMeter tests remains.

Journal article: Bianco, C. et al, “Genetic predisposition similarities between NASH and ASH: Identification of new therapeutic target”, JHEP Reports 3(3), 1^st June 2021.
Abstract
Fatty liver disease can be triggered by a combination of excess alcohol, dysmetabolism and other environmental cues, which can lead to steatohepatitis and can evolve to acute/chronic liver failure and hepatocellular carcinoma, especially in the presence of shared inherited determinants. The recent identification of the genetic causes of steatohepatitis is revealing new avenues for more effective risk stratification. Discovery of the mechanisms underpinning the detrimental effect of causal mutations has led to some breakthroughs in the comprehension of the pathophysiology of steatohepatitis. Thanks to this approach, hepatocellular fat accumulation, altered lipid droplet remodelling and lipotoxicity have now taken centre stage, while the role of adiposity and gut-liver axis alterations have been independently validated. This process could ignite a virtuous research cycle that, starting from human genomics, through omics approaches, molecular genetics and disease models, may lead to the development of new therapeutics targeted to patients at higher risk. Herein, we also review how this knowledge has been applied to: a) the study of the main PNPLA3 I148M risk variant, up to the stage of the first in-human therapeutic trials; b) highlight a role of MBOAT7 downregulation and lysophosphatidyl-inositol in steatohepatitis; c) identify IL-32 as a candidate mediator linking lipotoxicity to inflammation and liver disease. Although this precision medicine drug discovery pipeline is mainly being applied to non-alcoholic steatohepatitis, there is hope that successful products could be repurposed to treat alcohol-related liver disease as well.

Journal article: Vali, Y. et al, “FibroTest for Evaluating Fibrosis in Non-Alcoholic Fatty Liver Disease Patients: A Systematic Review and Meta-Analysis”, Journal of Clinical Medicine 10(11), 29^th May 2021.
Abstract
Background:
FibroTest™ is a multi-marker panel, suggested by guidelines as one of the surrogate markers with acceptable performance for detecting fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). A number of studies evaluating this test have been published after publication of the guidelines. This study aims to produce summary estimates of FibroTest™ diagnostic accuracy.
Methods:
Five databases were searched for studies that evaluated FibroTest™ against liver biopsy as the reference standard in NAFLD patients. Two authors independently screened the references, extracted data, and assessed the quality of included studies. Meta-analyses of the accuracy in detecting different levels of fibrosis were performed using the bivariate random-effects model and the linear mixed-effects multiple thresholds model.
Results:
From ten included studies, seven were eligible for inclusion in our meta-analysis. Five studies were included in the meta-analysis of FibroTest™ in detecting advanced fibrosis and five in significant fibrosis, resulting in an AUC of 0.77 for both target conditions. The meta-analysis of three studies resulted in an AUC of 0.69 in detecting any fibrosis, while analysis of three other studies showed higher accuracy in cirrhosis (AUC: 0.92).
Conclusions:
Our meta-analysis showed acceptable performance (AUC > 0.80) of FibroTest™ only in detecting cirrhosis. We observed more limited performance of the test in detecting significant and advanced fibrosis in NAFLD patients. Further primary studies with high methodological quality are required to validate the reliability of the test for detecting different fibrosis levels and to compare the performance of the test in different settings.

Journal article: Bianco, C. et al, “Non-invasive stratification of hepatocellular carcinoma risk in non-alcoholic fatty liver using polygenic risk score”, Journal of Hepatology 74(4), 1^st April 2021.
Abstract
Background & Aims:
Hepatocellular carcinoma (HCC) risk stratification in individuals with dysmetabolism is a major unmet need. Genetic predisposition contributes to non-alcoholic fatty liver disease (NAFLD). We aimed to exploit robust polygenic risk scores (PRS) that can be evaluated in the clinic to gain insight into the causal relationship between NAFLD and HCC, and to improve HCC risk stratification.
Methods:
We examined at-risk individuals (NAFLD cohort, n = 2,566; 226 with HCC; and a replication cohort of 427 German patients with NAFLD) and the general population (UK Biobank [UKBB] cohort, n = 364,048; 202 with HCC). Variants in PNPLA3-TM6SF2-GCKR-MBOAT7 were combined in a hepatic fat PRS (PRSHFC), and then adjusted for HSD17B13 (PRS-5).
Results:
In the NAFLD cohort, the adjusted impact of genetic risk variants on HCC was proportional to the predisposition to fatty liver (p = 0.002) with some heterogeneity in the effect. PRS predicted HCC more robustly than single variants (p <10^-13). The association between PRS and HCC was mainly mediated through severe fibrosis, but was independent of fibrosis in clinically relevant subgroups, and was also observed in those without severe fibrosis (p <0.05). In the UKBB cohort, PRS predicted HCC independently of classical risk factors and cirrhosis (p <10^-7). In the NAFLD cohort, we identified high PRS cut-offs (≥0.532/0.495 for PRS-HFC/PRS-5) that in the UKBB cohort detected HCC with ~90% specificity but limited sensitivity; PRS predicted HCC both in individuals with (p <10^-5) and without cirrhosis (p <0.05).
Conclusions:
Our results are consistent with a causal relationship between hepatic fat and HCC. PRS improved the accuracy of HCC detection and may help stratify HCC risk in individuals with dysmetabolism, including those without severe liver fibrosis. Further studies are needed to validate our findings.

Journal article: Armandi, A. et al, “Insulin Resistance across the Spectrum of Nonalcoholic Fatty Liver Disease”, Metabolites 11(3), 8^th March 2021.
Abstract
Insulin resistance (IR) is defined as a lower-than-expected response to insulin action from target tissues, leading to the development of type 2 diabetes through the impairment of both glucose and lipid metabolism. IR is a common condition in subjects with non-alcoholic fatty liver disease (NAFLD) and is considered one of the main factors involved in the pathogenesis of non-alcoholic steatohepatitis (NASH) and in the progression of liver disease. The liver, the adipose tissue and the skeletal muscle are major contributors for the development and worsening of IR. In this review, we discuss the sites and mechanisms of insulin action and the IR-related impairment along the spectrum of NAFLD, from simple steatosis to progressive NASH and cirrhosis.

Journal article: Govaere, O. et al, “Transcriptomic profiling across the Non-Alcoholic Fatty Liver Disease spectrum reveals gene signatures for steatohepatitis and fibrosis”, Science Translational Medicine 12(572), 2^nd December 2020.
Abstract

The mechanisms that drive nonalcoholic fatty liver disease (NAFLD) remain incompletely understood. This large multicenter study characterized the transcriptional changes that occur in liver tissue across the NAFLD spectrum as disease progresses to cirrhosis to identify potential circulating markers. We performed high-throughput RNA sequencing on a discovery cohort comprising histologically characterized NAFLD samples from 206 patients. Unsupervised clustering stratified NAFLD on the basis of disease activity and fibrosis stage with differences in age, aspartate aminotransferase (AST), type 2 diabetes mellitus, and carriage of PNPLA3 rs738409, a genetic variant associated with NAFLD. Relative to early disease, we consistently identified 25 differentially expressed genes as fibrosing steatohepatitis progressed through stages F2 to F4. This 25-gene signature was independently validated by logistic modeling in a separate replication cohort (n = 175), and an integrative analysis with publicly available single-cell RNA sequencing data elucidated the likely relative contribution of specific intrahepatic cell populations. Translating these findings to the protein level, SomaScan analysis in more than 300 NAFLD serum samples confirmed that circulating concentrations of proteins AKR1B10 and GDF15 were strongly associated with disease activity and fibrosis stage. Supporting the biological plausibility of these data, in vitro functional studies determined that endoplasmic reticulum stress up-regulated expression of AKR1B10, GDF15, and PDGFA, whereas GDF15 supplementation tempered the inflammatory response in macrophages upon lipid loading and lipopolysaccharide stimulation. This study provides insights into the pathophysiology of progressive fibrosing steatohepatitis, and proof of principle that transcriptomic changes represent potentially tractable and clinically relevant markers of disease progression.

Journal article: Hardy, T. et al “The European NAFLD Registry: A real-world longitudinal cohort study of nonalcoholic fatty liver disease”, Contemporary Clinical Trials 98, 1^st November 2020.
Abstract
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.

Editorial: Bianco, C. et al, “MAFLD vs NAFLD: Let the contest begin!”, Liver International 40(9), September 2020.

Journal article: Lee, J. et al, “Prognostic accuracy of FIB‐4, NAFLD fibrosis score, and APRI for NAFLD‐related events: a systematic review”, Liver International, 18^th September 2020.
Abstract
Background & Aims:
Fibrosis is the strongest predictor for long‐term clinical outcomes among patients with non‐alcoholic fatty liver disease (NAFLD). There is growing interest in employing non‐invasive methods for risk stratification based on prognosis. FIB‐4, NFS and APRI are models commonly used for detecting fibrosis among NAFLD patients. We aimed to synthesize existing literature on the ability of these models in prognosticating NAFLD‐related events.
Methods:
A sensitive search was conducted in two medical databases to retrieve studies evaluating the prognostic accuracy of FIB‐4, NFS and APRI among NAFLD patients. Target events were change in fibrosis, liver‐related event, and mortality. Two reviewers independently performed reference screening, data extraction and quality assessment (QUAPAS tool).
Results:
A total of 13 studies (FIB‐4: 12, NFS: 11, APRI: 10), published between 2013 and 2019, were retrieved. All studies were conducted in a secondary or tertiary care setting, with follow‐up ranging from one to 20 years. All three markers showed consistently good prognostication of liver‐related events (AUC from 0.69 to 0.92). For mortality, FIB‐4 (AUC of 0.67 to 0.82) and NFS (AUC of 0.70 to 0.83) outperformed APRI (AUC of 0.52 to 0.73) in all studies. All markers had inconsistent performance for predicting change in fibrosis stage.
Conclusions:
FIB‐4, NFS and APRI have demonstrated ability to risk stratify patients for liver‐related morbidity and mortality, with comparable performance to a liver biopsy, although more head‐to‐head studies are needed to validate this. More refined models to prognosticate NAFLD‐events may further enhance performance and clinical utility of non‐invasive markers.

Journal article: Lee, J. et al, “Accuracy of cytokeratin 18 (M30 and M65) in detecting non-alcoholic steatohepatitis and fibrosis: A systematic review and meta-analysis”, Plos One, 11^th September 2020.
Abstract
Introduction:
Association between elevated cytokeratin 18 (CK-18) levels and hepatocyte death has made circulating CK-18 a candidate biomarker to differentiate non-alcoholic fatty liver from non-alcoholic steatohepatitis (NASH). Yet studies produced variable diagnostic performance. We aimed to provide summary estimates with increased precision for the accuracy of CK-18 (M30, M65) in detecting NASH and fibrosis among non-alcoholic fatty liver disease (NAFLD) adults.
Methods:
We searched five databases to retrieve studies evaluating CK-18 against a liver biopsy in NAFLD adults. Reference screening, data extraction and quality assessment (QUADAS-2) were independently conducted by two authors. Meta-analyses were performed for five groups based on the CK-18 antigens and target conditions, using one of two methods: linear mixed-effects multiple thresholds model or bivariate logit-normal random-effects model.
Results:
We included 41 studies, with data on 5,815 participants. A wide range of disease prevalence was observed. No study reported a pre-defined cut-off. Thirty of 41 studies provided sufficient data for inclusion in any of the meta-analyses. Summary AUC [95% CI] were: 0.75 [0.69–0.82] (M30) and 0.82 [0.69–0.91] (M65) for NASH; 0.73 [0.57–0.85] (M30) for fibrotic NASH; 0.68 (M30) for significant (F2-4) fibrosis; and 0.75 (M30) for advanced (F3-4) fibrosis. Thirteen studies used CK-18 as a component of a multimarker model.
Conclusions:
For M30 we found lower diagnostic accuracy to detect NASH compared to previous meta-analyses, indicating a limited ability to act as a stand-alone test, with better performance for M65. Additional external validation studies are needed to obtain credible estimates of the diagnostic accuracy of multimarker models.

Journal article: Valenti, L., Jamialahmadi, O. & Romeo, S., “Lack of genetic evidence that fatty liver disease predisposes to COVID-19”, Journal of Hepatology 73(3), 1^st September 2020.

Journal article: Vali, Y. et al, “Enhanced liver fibrosis test for the non-invasive diagnosis of fibrosis in patients with NAFLD: A systematic review and meta-analysis”, Journal of Hepatology 73(2), August 2020.

Abstract
Background & Aims:
The enhanced liver fibrosis (ELF) test has been proposed for the non-invasive assessment of advanced fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). We performed a systematic review to estimate the accuracy of this test against biopsy.
Methods:
In this systematic review, we searched MEDLINE, Embase, Web of Science and the Cochrane Library for studies that included patients with NAFLD and that used both liver biopsy (as the reference standard) and the ELF test. Two authors independently screened the references, extracted the data and assessed the quality of included studies. Due to the variation in reported thresholds, we used a multiple thresholds random effects model for meta-analysis (diagmeta R-package).
Results:
The meta-analysis of 11 studies reporting advanced fibrosis and 5 studies reporting significant fibrosis showed that the ELF test had a sensitivity of >0.90 for excluding fibrosis at a threshold of 7.7. However, as a diagnostic test at high thresholds, the test only achieved specificity and positive predictive value >0.80 in very high prevalence settings (>50%). To achieve a specificity of 0.90 for advanced and significant fibrosis, thresholds of 10.18 (sensitivity: 0.57) and 9.86 (sensitivity: 0.55) were required, respectively.
Conclusion:
The ELF test showed high sensitivity but limited specificity to exclude advanced and significant fibrosis at low cut-offs. The diagnostic performance of the test at higher thresholds was found to be more limited in low-prevalence settings. We conclude that clinicians should carefully consider the likely disease prevalence in their practice setting and adopt suitable test thresholds to achieve the desired performance.

Journal article: McSweeney, L. et al, “Health-related quality of life and patient-reported outcome measures in NASH-related cirrhosis”, JHEP Reports 2(3), June 2020.

Abstract
Background & Aims:
Non-alcoholic steatohepatitis (NASH) is known to have a negative impact on patients’ health-related quality of life (HRQoL), even before progression to cirrhosis has occurred. The burden of NASH-related cirrhosis from the patient perspective remains poorly understood. Herein, we aimed to identify the burden of disease and HRQoL impairment among patients with NASH-related compensated cirrhosis.
Methods:
This targeted literature review sought first to identify the humanistic burden of disease from the perspective of patients with diagnosed NASH-cirrhosis and, secondly, to identify generic or disease-specific patient-reported outcome measures (PROMs) used to assess the impact of NASH-cirrhosis. Searches were conducted in bibliographical databases, grey or unpublished literature, liver disease websites, support group websites and online blogs. A quality assessment of specific PROMs was conducted.
Results:
Patients with NASH-cirrhosis are reported to suffer from lower HRQoL than patients with non-cirrhotic NASH and the general population with respect to physical health/functioning, emotional health and worry, and mental health. Thirteen PROMs were identified, of which 4 were liver-disease specific: CLDQ, CLDQ-NAFLD, LDQoL and LDSI. The most commonly used measures do not comply with current industry or regulatory standards for PROMs and/or are not validated for use in a cirrhotic NASH population.
Conclusions:
Patients with NASH-cirrhosis have lower HRQoL and poorer physical health than patients with non-cirrhotic NASH. However, the literature lacked detail of the everyday impact on patients’ lives. Currently, a number of PROMs are available to measure the impact of the disease in patients with chronic liver conditions. The lack of studies that include qualitative insights in this population mandates further exploration and research.

Journal article: Aron-Wisnewsky, J. et al, “Nonalcoholic Fatty Liver Disease: Modulating Gut Microbiota to Improve Severity?”, Gastroenterology 158(7), May 2020.

Abstract
Gut microbiota plays a role in the pathophysiology of metabolic diseases, which include nonalcoholic fatty liver diseases, through the gut–liver axis. To date, clinical guidelines recommend a weight loss goal of 7%–10% to improve features of nonalcoholic fatty liver diseases. Because this target is not easily achieved by all patients, alternative therapeutic options are currently being evaluated. This review focuses on therapeutics that aim to modulate the gut microbiota and the gut–liver axis. We discuss how probiotics, prebiotics, synbiotic, fecal microbiota transfer, polyphenols, specific diets, and exercise interventions have been found to modify gut microbiota signatures; improve nonalcoholic fatty liver disease outcomes; and detail, when available, the different mechanisms by which these beneficial outcomes might occur. Apart from probiotics that have already been tested in human randomized controlled trials, most of these potential therapeutics have been studied in animals. Their efficacy still warrants confirmation in humans using appropriate design.

Journal article: Luukkonen, P.K. et al, “Hydroxysteroid 17-β dehydrogenase 13 variant increases phospholipids and protects against fibrosis in nonalcoholic fatty liver disease”, JCI insight 5(5), March 2020.

Abstract
Carriers of the hydroxysteroid 17-β dehydrogenase 13 (HSD17B13) gene variant (rs72613567:TA) have a reduced risk of NASH and cirrhosis but not steatosis. We determined its effect on liver histology, lipidome, and transcriptome using ultra performance liquid chromatography-mass spectrometry and RNA-seq. In carriers and noncarriers of the gene variant, we also measured pathways of hepatic fatty acids (de novo lipogenesis [DNL] and adipose tissue lipolysis [ATL] using ²H₂O and ²H-glycerol) and insulin sensitivity using ³H-glucose and euglycemic-hyperinsulinemic clamp) and plasma cytokines. Carriers and noncarriers had similar age, sex and BMI. Fibrosis was significantly less frequent while phospholipids, but not other lipids, were enriched in the liver in carriers compared with noncarriers. Expression of 274 genes was altered in carriers compared with noncarriers, consisting predominantly of downregulated inflammation-related gene sets. Plasma IL-6 concentrations were lower, but DNL, ATL and hepatic insulin sensitivity were similar between the groups. In conclusion, carriers of the HSD17B13 variant have decreased fibrosis and expression of inflammation-related genes but increased phospholipids in the liver. These changes are not secondary to steatosis, DNL, ATL, or hepatic insulin sensitivity. The increase in phospholipids and decrease in fibrosis are opposite to features of choline-deficient models of liver disease and suggest HSD17B13 as an attractive therapeutic target.

Journal article: Aron-Wisnewsky, J. et al, “Gut microbiota and human NAFLD: disentangling microbial signatures from metabolic disorders”, Nature Reviews Gasteroenterology & Hepatology 17, March 2020.

Abstract
Gut microbiota dysbiosis has been repeatedly observed in obesity and type 2 diabetes mellitus, two metabolic diseases strongly intertwined with non-alcoholic fatty liver disease (NAFLD). Animal studies have demonstrated a potential causal role of gut microbiota in NAFLD. Human studies have started to describe microbiota alterations in NAFLD and have found a few consistent microbiome signatures discriminating healthy individuals from those with NAFLD, non-alcoholic steatohepatitis or cirrhosis. However, patients with NAFLD often present with obesity and/or insulin resistance and type 2 diabetes mellitus, and these metabolic confounding factors for dysbiosis have not always been considered. Patients with different NAFLD severity stages often present with heterogeneous lesions and variable demographic characteristics (including age, sex and ethnicity), which are known to affect the gut microbiome and have been overlooked in most studies. Finally, multiple gut microbiome sequencing tools and NAFLD diagnostic methods have been used across studies that could account for discrepant microbiome signatures. This Review provides a broad insight into microbiome signatures for human NAFLD and explores issues with disentangling these signatures from underlying metabolic disorders. More advanced metagenomics and multi-omics studies using system biology approaches are needed to improve microbiome biomarkers.

Journal article: Meroni, M. et al, “MBOAT7 down-regulation by hyper-insulinemia induces fat accumulation in hepatocytes”, EBioMedicine 52, February 2020.

Abstract
Background:
Naturally occurring variation in Membrane-bound O-acyltransferase domain-containing 7 (MBOAT7), encoding for an enzyme involved in phosphatidylinositol acyl-chain remodelling, has been associated with fatty liver and hepatic disorders. Here, we examined the relationship between hepatic MBOAT7 down-regulation and fat accumulation.
Methods:
Hepatic MBOAT7 expression was surveyed in 119 obese individuals and in experimental models. MBOAT7 was acutely silenced by antisense oligonucleotides in C57Bl/6 mice, and by CRISPR/Cas9 in HepG2 hepatocytes.
Findings:
In obese individuals, hepatic MBOAT7 mRNA decreased from normal liver to steatohepatitis, independently of diabetes, inflammation and MBOAT7 genotype. Hepatic MBOAT7 levels were reduced in murine models of fatty liver, and by hyper-insulinemia. In wild-type mice, MBOAT7 was down-regulated by refeeding and insulin, concomitantly with insulin signalling activation. Acute hepatic MBOAT7 silencing promoted hepatic steatosis I and enhanced expression of fatty acid transporter Fatp1. MBOAT7 deletion in hepatocytes reduced the incorporation of arachidonic acid into phosphatidylinositol, consistently with decreased enzymatic activity, determining the accumulation of saturated triglycerides, enhanced lipogenesis and FATP1 expression, while FATP1 deletion rescued the phenotype.
Interpretation:
MBOAT7 down-regulation by hyper-insulinemia contributes to hepatic fat accumulation, impairing phosphatidylinositol remodelling and up-regulating FATP1.

Journal article: Karsdal, M.A. et al, “Is the Total Amount as Important as Localization and Type of Collagen in Liver Fibrosis Attributable to Steatohepatitis?”, Hepatology 71(1), January 2020.

Journal article: Majo, J. et al, “Pathology and natural history of organ fibrosis”, Current Opinion in Pharmacology 49, December 2019.

Abstract
Histopathological assessment of fibrosis focusing on morphological patterns provides important information for the management of patients with chronic diseases of the kidney, liver and the lung. This review summarizes key histopathological features of pulmonary, renal and hepatic fibrosis and discusses advances in the understanding of the pathogenesis of pulmonary fibrosis and pathogenetic insights with translational implications for renal fibrosis. The review also tackles new staging approaches based on liver fibrosis dynamics and evaluation of fibrosis regression, digital pathology and second harmonic generation microscopy methods for hepatic fibrosis assessment and critical appraisal of non-invasive tests for liver and renal fibrosis evaluation.

Journal article: Nielsen, M.J. et al, “Serum markers of type III and IV procollagen processing predict recurrence of fibrosis in liver transplanted patients”, Scientific Reports 9, October 2019.

Abstract
Following liver transplantation (LT), 10–30% of patients develop recurrent cirrhosis (RC). There is an urgent need for predictive non-invasive markers for improved monitoring of these patients. Here we studied extracellular matrix biomarkers as predictors of RC after LT. Forty-seven LT patients were divided into groups of fast, intermediate or non-progressors towards RC (<1 year, 3–5 years or no advanced fibrosis >5 years after LT), assessed by follow-up liver biopsies. Markers of interstitial matrix type III and V collagen formation (PRO-C3 and PRO-C5), basement membrane type IV collagen formation (PRO-C4) and degradation (C4M) were assessed in serum samples collected 3, 6 and 12 months post-LT using specific ELISAs. PRO-C3, PRO-C4, and C4M were elevated in fast progressors compared to non-progressors 3 months after LT. C4M and PRO-C4 additionally differentiated between intermediate and fast progressors at 3 months. PRO-C3 was best predictor of survival, with LT patients in the highest PRO-C3 tertile having significantly shorter survival time. This shows that interstitial matrix and basement membrane remodeling in RC may be distinguishable. Markers originating from different sites in the extracellular matrix could be valuable tools for a more dynamic monitoring of patients at risk of RC. However, this needs validation in larger cohorts.

Journal article: Luukkonen, P.K. et al, “Human PNPLA3-I148M variant increases hepatic retention of polyunsaturated fatty acids”, JCI insight 4(16), August 2019.

Abstract
The common patatin-like phospholipase domain–containing protein 3 (PNPLA3) variant I148M predisposes to nonalcoholic liver disease but not its metabolic sequelae. We compared the handling of labeled polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SFA) in vivo in humans and in cells harboring different PNPLA3 genotypes. In 148M homozygous individuals, triglycerides (TGs) in very low–density lipoproteins (VLDL) were depleted of PUFAs both under fasting and postprandial conditions compared with 148I homozygotes, and the PUFA/SFA ratio in VLDL-TGs was lower relative to the chylomicron precursor pool. In human PNPLA3-148M and PNPLA3-KO cells, PUFA but not SFA incorporation into TGs was increased at the expense of phosphatidylcholines, and under lipolytic conditions, PUFA-containing diacylglycerols (DAGs) accumulated compared with PNPLA3-148I cells. Polyunsaturated TGs were increased, while phosphatidylcholines (PCs) were decreased in the human liver in 148M homozygous individuals as compared with 148I homozygotes. We conclude that human PNPLA3-I148M is a loss-of-function allele that remodels liver TGs in a polyunsaturated direction by impairing hydrolysis/transacylation of PUFAs from DAGs to feed phosphatidylcholine synthesis.

Journal article: Farrell, G. et al, “Mouse Models of Nonalcoholic Steatohepatitis: Toward Optimization of Their Relevance to Human Nonalcoholic Steatohepatitis”, Hepatology 69(5), May 2019.

Abstract
Nonalcoholic steatohepatitis (NASH) arises from a variable interplay between environmental factors and genetic determinants that cannot be completely replicated in animals. Notwithstanding, preclinical models are needed to understand NASH pathophysiology and test mechanism-based therapies. Among several mouse models of NASH, some exhibit the key pathophysiologic as well as histopathologic criteria for human NASH, whereas others may be useful to address specific questions. Models based on overnutrition with adipose restriction/inflammation and metabolic complications, particularly insulin resistance, may be most useful to investigate critical etiopathogenic factors. In-depth pathologic description is required for all models. Some models demonstrate hepatocyte ballooning, which can be confused with microvesicular steatosis, whereas demonstration of an inflammatory infiltrate and pattern of liver fibrosis compatible with human NASH is desirable in models used for pharmacologic testing. When mice with specific genetic strains or mutations that cause overeating consume a diet enriched with fat, modest amounts of cholesterol, and/or simple sugars (“Western diet”), they readily develop obesity with liver disease similar to human NASH, including significant fibrosis. Purely dietary models, such as high-fat/high-cholesterol, Western diet, and choline-deficient, amino acid–defined, are similarly promising. We share concern about using models without weight gain, adipose pathology, or insulin resistance/hyperinsulinemia and with inadequate documentation of liver pathology. NASH-related fibrosis is a key endpoint in trials of possible therapies. When studied for this purpose, NASH models should be reproducible and show steatohepatitis (ideally with ballooning) and at least focal bridging fibrosis, while metabolic factors/disordered lipid partitioning should contribute to etiopathogenesis. Because murine models are increasingly used to explore pharmacologic therapies for NASH, we propose a minimum set of requirements that investigators, drug companies, and journals should consider to optimize their translational value.

Journal article: Younes, R. & Bugianesi, E., “NASH in lean individuals”, Seminars in Liver Disease 39(01), January 2019.

Abstract
Nonalcoholic fatty liver disease (NAFLD) is generally associated with obesity and the related comorbidities but it can also develop in subjects with a body mass index (BMI) within the ethnic-specific cutoff of 25 kg/m2 BMI in Caucasian and 23 kg/m2 in Asian subjects, the so-called “lean” NAFLD. This sub-phenotype of NAFLD patients has been described across populations of different ethnicity, particularly in Asia, but it can be diagnosed in 10 to 20% of nonobese Americans and Caucasians. Pathophysiological mechanisms underpinning the “lean” phenotype are not completely understood, but they may include a more dysfunctional fat (visceral obesity, differences in adipocyte differentiation and altered lipid turnover), altered body composition (decreased muscle mass), a genetic background, not limited to patatin-like phospholipase domain-containing protein 3 (PNPLA3) C > G polymorphisms, epigenetic changes occurring early in life and a different pattern of gut microbiota. Lean subjects with NAFLD have milder features of the metabolic syndrome when compared with obese patients. Nonetheless they have a higher prevalence of metabolic alterations (e.g., dyslipidemia, arterial hypertension, insulin resistance, and diabetes) compared with healthy controls. Data on histological severity are controversial, but they can develop the full spectrum of liver disease associated with nonalcoholic steatohepatitis NASH. Since lean NAFLD usually present with less obesity-related comorbidities, it is commonly believed that this group would follow a relatively benign clinical course but recent data challenge this concept. Here, the authors describe the current knowledge about NAFLD in lean individuals and highlight the unanswered questions and gaps in the field.