MAFLD: How is it different from NAFLD?

"Metabolic dysfunction-associated fatty liver disease (MAFLD)" is the term suggested in 2020 to refer to fatty liver disease related to systemic metabolic dysregulation. The name change from nonalcoholic fatty liver disease (NAFLD) to MAFLD comes with a simple set of criteria to enable easy diagnosis at the bedside for the general medical community, including primary care physicians. Since the introduction of the term, there have been key areas in which the superiority of MAFLD over the traditional NAFLD terminology has been demonstrated, including for the risk of liver and extrahepatic mortality, disease associations, and for identifying high-risk individuals. Additionally, MAFLD has been adopted by a number of leading pan-national and national societies due to its concise diagnostic criterion, removal of the requirement to exclude concomitant liver diseases, and reduction in the stigma associated with this condition. The current article explores the differences between MAFLD and NAFLD diagnosis, areas of benefit, some potential limitations, and how the MAFLD terminology has opened up new fields of research.

Clinical and Molecular Biomarkers for Diagnosis and Staging of NAFLD.

Non-alcoholic fatty liver disease (NAFLD) is the most common hepatic pathology in industrialized countries, affecting about 25% of the general population. NAFLD is a benign condition, however, it could evolve toward more serious diseases, including non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and finally, hepatocellular carcinoma (HCC). Liver biopsy is still the gold standard for NAFLD diagnosis. Due to the risks associated with liver biopsy and the impossibility to apply it on a large scale, it is now necessary to identify non-invasive biomarkers, which may reliably identify patients at higher risk of progression. Therefore, several lines of research have tried to address this issue by identifying novel biomarkers using omics approaches, including lipidomics, metabolomics and RNA molecules' profiling. Thus, in this review, we firstly report the conventional biomarkers used in clinical practice for NAFL and NASH diagnosis as well as fibrosis staging, and secondly, we pay attention to novel biomarkers discovered through omics approaches with a particular focus on RNA biomarkers (microRNAs, long-noncoding RNAs), showing promising diagnostic performance for NAFL/NASH diagnosis and fibrosis staging.

Performance of non-invasive fibrosis scores in non-alcoholic fatty liver disease with and without morbid obesity.

BACKGROUND: Non-invasive scores, such as the non-alcoholic fatty liver disease (NAFLD) Fibrosis Score (NFS), are increasingly used for liver fibrosis assessment in patients with NAFLD. The aim of this study was to assess the applicability and reliability of non-invasive fibrosis scores in NAFLD patients with and without morbid obesity. METHODS: Three hundred sixty-eight patients with biopsy-proven NAFLD identified between January 2012 and December 2015 were studied; 225 with morbid obesity (biopsy obtained during bariatric surgery) and 143 patients without (termed as "conventional"). RESULTS: Median age was 47 years, 57% were female. Median body mass index (BMI) was 42.9 kg/m2 with significant differences between our conventional and morbidly obese patients (BMI 29.0 vs. 50.8 kg/m2, p < 0.001). Overall, 42% displayed mild/moderate and 16% advanced liver fibrosis (stage III/IV). All tested scores were significantly linked to fibrosis stage (p < 0.001 for all). FIB-4 (AUROC 0.904), APRI (AUROC 0.848), and NFS (AUROC 0.750) were identified as potent predictors of advanced fibrosis, although NFS overestimated fibrosis stage in morbid obesity. Limiting BMI to a maximum of 40 kg/m2 improved NFS' overall performance (AUROC 0.838). FIB-4 > 1.0 indicated high probability of advanced fibrosis (OR = 29.1). FIB-4 predicted advanced fibrosis independently from age, sex, BMI, and presence of morbid obesity. CONCLUSIONS: Our data suggest that FIB-4 score is an accurate predictor of advanced fibrosis in NAFLD throughout all BMI stages. Without adjustment, NFS tends to overestimate fibrosis in morbidly obese NAFLD patients. This problem may be solved by implementation of an upper BMI limit (for NFS) or adjustment of diagnostic thresholds.

A single-letter change in an acronym: signals, reasons, promises, challenges, and steps ahead for moving from NAFLD to MAFLD.

Introduction: We are currently at the dawn of a revolution in the field of fatty liver diseases. Recently, a consensus recommended 'metabolic (dysfunction) associated fatty liver disease' (MAFLD) as a more appropriate name to describe fatty liver disease associated with metabolic dysfunction, ultimately suggesting that the old acronym nonalcoholic fatty liver disease (NAFLD) should be abandoned.Areas covered: In this viewpoint, we discuss the reasons and relevance of this semantic modification through five different conceptual domains, i.e., 1) signals, 2) reasons, 2) promises, 4) challenges and 5) steps ahead.Expert opinion: The road ahead will not be traveled without major challenges. Further research to evaluate the positive and negative impacts of the nomenclature change is warranted. However, this modification should encourage increased disease awareness among policymakers and stimulate public and private investments leading to more effective therapy development.

Validating candidate biomarkers for different stages of non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is a common chronic condition caused by the accumulation of fat in the liver. NAFLD may range from simple steatosis to advanced cirrhosis, and affects more than 1 billion people around the world. To date, there has been no effective treatment for NAFLD. In this study, we evaluated the expression of 4 candidate NAFLD biomarkers to assess their possible applicability in the classification and treatment of the disease.Twenty-six obese subjects, who underwent bariatric surgery, were recruited and their liver biopsies obtained. Expression of 4 candidate biomarker genes, PNPLA3, COL1A1, PPP1R3B, and KLF6 were evaluated at gene and protein levels by RT-qPCR and enzyme-linked immunosorbent assay (ELISA), respectively.A significant increase in the levels of COL1A1 protein (P = .03) and PNPLA3 protein (P = .03) were observed in patients with fibrosis-stage NAFLD compared to that in patients with steatosis-stage NAFLD. However, no significant differences were found in abundance of PPP1R3B and KLF6 proteins or at the gene level for any of the candidate.This is the first study, to our knowledge, to report on the expression levels of candidate biomarker genes for NAFLD in the Saudi population. Although PNPLA3 and PPP1R3B had been previously suggested as biomarkers for steatosis and KLF6 as a possible marker for the fibrosis stage of NAFLD, our results did not support these findings. However, other studies that had linked PNPLA3 to fibrosis in advanced NAFLD supported our current finding of high PNPLA3 protein in patients with fibrosis. Additionally, our results support COL1A1 protein as a potential biomarker for the fibrosis stage of NAFLD, and indicate its use in the screening of patients with NAFLD. Further studies are required to validate the use of COL1A1 as a biomarker for advanced NAFLD in a larger cohort.

[NASH: new terminology and what else is new in 2020]. / NASH†: nouvelle terminologie et nouveautés en 2020.

Non-alcoholic fatty liver disease (NAFLD) includes a spectrum of hepatic pathology ranging from non-alcoholic fatty liver, non-alcoholic steatohepatitis (NASH) occasionally complicated with hepatic fibrosis or even cirrhosis. In order to propose a diagnosis with positive criteria, a panel of experts recently proposed the use of an alternative nomenclature, metabolic-dysfunction-associated fatty liver disease (MAFLD) whose use remains debated. In addition, in Switzerland and elsewhere, there is strong epidemiological growth of NAFLD. The next years will probably see the approval of new therapies for NAFLD/NASH but, at present, management remains focused on lifestyle interventions and joint monitoring by the primary care physician and, when necessary, the specialist.

La stéatopathie non alcoolique (NAFLD) comprend un spectre de pathologies allant de la stéatose hépatique non alcoolique à la stéatohépatite non alcoolique (NASH) parfois compliquée d'une fibrose hépatique, voire d'une cirrhose. Afin de proposer un diagnostic avec des critères positifs, un panel d'experts a récemment proposé l'utilisation d'une nomenclature alternative, la stéatopathie associée à la dysfonction métabolique (Metabolic-Dysfunction-Associated Fatty Liver Disease, MAFLD) dont l'utilisation reste discutée. D'autre part, la NAFLD est en pleine croissance épidémiologique en Suisse comme ailleurs. Les prochaines années vont probablement voir l'approbation de nouvelles thérapeutiques pour la NAFLD/NASH mais, à l'heure actuelle, la prise en charge reste centrée sur les mesures hygiéno-diététiques et le suivi conjoint par le médecin de premier recours et, si nécessaire, par le spécialiste.

Estudio descriptivo de la esteatosis hepática y la morbilidad asociada en atención primaria. (Estudio ESTEATOAP) / Descriptive study of hepatic steatosis and associated morbidity in Primary Care. (ESTEATOAP Study)

OBJETIVO: Estudiar la prevalencia registrada de esteatosis hepática en atención primaria, así como la proporción de pacientes con diagnóstico de EHGNA que incluye el hígado graso simple no alcohólico (HGNA) y de esteatohepatitis no alcohólica frente a la esteatosis por otras causas. Además, se estudió la proporción de las morbilidades cardiometabólicas asociadas al HGNA. MATERIAL Y MÉTODOS: Estudio observacional descriptivo. La población de estudio es la de todos los pacientes con diagnóstico registrado de esteatosis hepática en un Centro de Salud urbano que atiende a una población de 25.747 mayores de 14 años. Se calculó un tamaño muestral de 229 pacientes. Se describen las características demográficas y clínicas asociadas. RESULTADOS: La prevalencia de esteatosis fue del 2,17%. Y de EHGNA del 1,51%. La media de edad de 62,42. Mujeres 114 mujeres (50,2%) y 113 varones (49,8%). Ciento cuarenta y siete (64,8%) fueron EHGNA y 64 (28,2%) fueron esteatosis por otras causas. La proporción de pacientes con EHGNA y transaminasas elevadas fue del 24,13% y la proporción de pacientes con EHGNA y elevación de GGT fue el 18,6%. Se ha encontrado una proporción elevada de EHGNA con factores de riesgo cardiometabólico: 93,9% de sobrepeso y obesidad, 55,1% de diabetes, 54,4% de hipertensión, 32,9% de síndrome metabólico, 35,2% hipertrigliceridemia y HDL de riesgo 19,6%. Entre los factores de riesgo cardiometabólicos y la EHGNA se encontró relación significativa en la diabetes, la obesidad y el síndrome metabólico. DISCUSIÓN: La prevalencia fue de solo el 1,51%, quizás por la escasa importancia que se da a esta enfermedad. Hay una proporción alta de EHGNA con factores de riesgo cardiometabólicos y más en la población general. Si se consideran todas las causas de esteatosis hay una asociación significativa entre obesidad, diabetes mellitus y síndrome metabólico con la EHGNA. CONCLUSIONES: La prevalencia registrada de EHGNA es muy inferior a la de los estudios poblacionales, además se ha encontrado una alta presencia de los factores cardiometabólicos en estos pacientes

OBJECTIVE: To study the recorded prevalence of hepatic steatosis in Primary Care, as well as the proportion of patients diagnosed with fatty liver diseases (FLD) including simple non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) versus steatosis by other causes. In addition, the proportion of cardiometabolic morbidities associated with NAFLD liver was studied. MATERIAL AND METHODS: A descriptive observational study was carried out on a population that included all patients with a recorded diagnosis of hepatic steatosis in an urban health centre that serves a population of 25,747 over the age of 14. A sample size of 229 patients was calculated. The demographic and clinical characteristics associated with hepatic steatosis are described. RESULTS: The prevalence of steatosis was 2.17% and 1.51% for NAFLD. The mean age was 62.42 years. The study included 114 (50.2%) women and 113 (49.8%) males. NAFLD was found in 147 (64.8%), and 64 (28.2%) were steatosis due to other causes. The proportion of patients with NAFLD and high transaminases was 24.13%, and the proportion of patients with NAFLD and GGT elevation was 18.6%. A high proportion of NAFLD had been found with cardiometabolic risk factors: 93.9% overweight and obesity, 55.1% diabetes, 54.4% hypertension, 32.9% metabolic syndrome, 35.2% hypertriglyceridaemia, and HDL risk 19.6%. A significant association was found between cardiometabolic risk factors and NAFLD in diabetes, obesity, and metabolic syndrome. DISCUSSION: Prevalence was only 1.51%, perhaps because of the low importance given to this disease. There is a high proportion of NAFLD with cardiometabolic risk factors and more in the general population. If all the causes of steatosis are considered there is a significant association between obesity, diabetes mellitus, and metabolic syndrome with NAFLD. CONCLUSIONS: The recorded prevalence of NAFLD is much lower than that of population studies, and a high presence of cardiometabolic factors has been found in these patients

La ecografía, técnica diagnóstica en esteatosis hepática no alcohólica / Ecography, diagnostic technique in non-alcoholic hepatic esteatosis

OBJETIVO: Analizar le ecografia como prueba diagnostica de la esteatosis hepática no alcohólica. MÉTODO: Estudio observacional, descriptivo y analítico, de sección transversal. Durante 12 meses se seleccionaron 100 pacientes, con 2 o más factores de riesgo cardiovascular, con nula o baja ingesta de alcohol, que acudían a consulta de Atención Primaria. Determinaciones efectuadas. Variables demográficas y bioquímicas: Edad. Género. Ingesta de alcohol. Historia de diabetes, hipertensión arterial sistémica. Peso, talla, índice de masa corporal (IMC). Medición de presión arterial. Niveles de glucosa basal, hemoglobina glicosilada. Colesterol total, colesterol HDL, colesterol LDL, Triglicéridos, AST, ALT, bilirrubinas y fosfatasa alcalina. También se recogieron antecedentes personales y familiares de diabetes, HTA, dislipemia, tratamiento farmacológico, cifras de otros parámetros analíticos y perímetro abdominal. Evaluación hepática por ultrasonografía. Una vez cumplían los criterios de selección eran citados para la realización de la ecografía de abdomen completo, previa información del propósito de la técnica a efectuar y aportando el consentimiento informado firmado. La ecografía se realizaba con el paciente en ayunas y a ser posible con vejiga repleccionada, para poder efectuar la técnica en las mejores condiciones de preparación del paciente, con el fin de disminuir los artefactos ecográficos y poder valorar todas las estructuras abdominales correctamente. Analisis Estadístico con programa SPSS 23. Las variables cualitativas se exponen como valor exacto y en porcentaje, las cuantitativas como media y desviación estándar (DE). La comparación entre medias se realizó a través de la prueba t de Student para grupos independientes o la U de Mann-Whitney si las condiciones de normalidad (aplicación del test de Kolmogorov- Smirnoff o de Shapiro Willks) no se cumplían. En las variables cualitativas, la prueba de Ji al cuadrado. RESULTADOS: Han participado 100 pacientes: 44 hombres y 56 mujeres, con una edad media de 61,84. El 71% de los sujetos tienen obesidad. El 23 % de los sujetos no tiene esteatosis, y en el 58 % es de grado leve y moderado en ambos géneros (p< 0,003). El 19 % tiene esteatosis grado 3. Los factores de riesgo más prevalentes de los pacientes estudiados son obesidad, que la presentan el 78 % de ellos, hipercolesterolemia el 73 %, DM el 62 % e HTA el 59 %. CONCLUSIONES: La ecografía es la modalidad de elección para la determinación cualitativa de esteatosis, pero es una prueba subjetiva y dependiente del operador: sólo detecta infiltración grasa de moderada a grave

OBJECTIVE: To analyze the ultrasound as a diagnostic test for non-alcoholic liver steatosis. METHOD: Observational, descriptive and analytical study, of cross section. For 12 months, 100 patients were selected, with 2 or more cardiovascular risk factors, with no or low alcohol intake, who attended Primary Care. Determinations made: Demographic and biochemical variables: Age. Gender. Alcohol intake. History of diabetes, systemic arterial hypertension. Weight, height, body mass index (BMI). Blood pressure measurement Basal glucose levels, glycosylated hemoglobin. Total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, AST, ALT, bilirubins and alkaline phosphatase. Personal and family history of diabetes, HBP, dyslipidemia, drug treatment, figures of other analytical parameters and abdominal perimeter were also collected. Hepatic evaluation by ultrasonography: Once they met the selection criteria, they were cited for the realization of the ultrasound of the entire abdomen, prior information on the purpose of the technique to be performed and providing the signed informed consent. The ultrasound was performed with the patient on an empty stomach and, if possible, with a bladder replenished, in order to perform the technique in the best conditions of preparation of the patient, in order to reduce the ultrasound devices and to assess all the abdominal structures correctly. Statistical Analysis with SPSS program 23. The qualitative variables are shown as exact value and in percentage, the quantitative variables as mean and standard deviation (SD). The comparison between means was made through the Student t test for independent groups or the Mann-Whitney U test if the normal conditions (application of the Kolmogorov-Smirnoff or Shapiro Willks test) were not met. In qualitative variables, the chi-square test. RESULTS: 100 patients participated: 44 men and 56 women, with a mean age of 61.84. 71% of subjects are obese. 23% of the subjects do not have steatosis, and in 58% it is mild and moderate in both genders (p <0.003). 19% have grade 3 steatosis. The most prevalent risk factors of the patients studied are obesity, which is presented by 78% of them, hypercholesterolemia 73%, DM 62% and HT 59%. CONCLUSIONS: Ultrasound is the modality of choice for the qualitative determination of steatosis, but it is a subjective and operator-dependent test: it only detects moderate to severe fat infiltration

MAFLD: A Consensus-Driven Proposed Nomenclature for Metabolic Associated Fatty Liver Disease.

Fatty liver associated with metabolic dysfunction is common, affects a quarter of the population, and has no approved drug therapy. Although pharmacotherapies are in development, response rates appear modest. The heterogeneous pathogenesis of metabolic fatty liver diseases and inaccuracies in terminology and definitions necessitate a reappraisal of nomenclature to inform clinical trial design and drug development. A group of experts sought to integrate current understanding of patient heterogeneity captured under the acronym nonalcoholic fatty liver disease (NAFLD) and provide suggestions on terminology that more accurately reflects pathogenesis and can help in patient stratification for management. Experts reached consensus that NAFLD does not reflect current knowledge, and metabolic (dysfunction) associated fatty liver disease "MAFLD" was suggested as a more appropriate overarching term. This opens the door for efforts from the research community to update the nomenclature and subphenotype the disease to accelerate the translational path to new treatments.

Clinical validation of the FLIP algorithm and the SAF score in patients with non-alcoholic fatty liver disease.

BACKGROUND & AIMS: Histological classifications used to diagnose/stage non-alcoholic fatty liver disease (NAFLD) are based on morphology, with undetermined clinical correlates and relevance. We assessed the clinical relevance of the fatty liver inhibition of progression (FLIP) algorithm and the steatosis, activity, and fibrosis (SAF) scoring system. METHODS: One hundred and forty consecutive patients with suspected NAFLD and a separate validation cohort of 78 patients enrolled in a therapeutic trial, all with central reading of liver biopsy, were included. FLIP and SAF were used to categorize patients with non-alcoholic steatohepatitis (NASH), non-NASH NAFLD (NAFL), or non-NAFLD. The SAF activity score assessed hepatocyte ballooning and lobular inflammation; a histologically severe disease was defined as a SAF activity score of ≥3 and/or bridging fibrosis or cirrhosis. Clinical, biochemical, and metabolic data were analyzed in relation to histology. RESULTS: Patients with NASH according to the FLIP algorithm had a clinical profile distinct from those with NAFL, with a higher prevalence of metabolic risk factors (increased body mass index [BMI], central obesity, serum glucose, and glycated hemoglobin), more severe insulin resistance (fasting insulin and homeostasis model assessment for insulin resistance [HOMA-IR] values), and higher levels of aminotransferases. Similar findings were documented for patients with severe disease vs. those without. Positive linear trends existed between NASH or severe disease and increasing BMI and HOMA-IR. There was a strong association between liver fibrosis and NASH or SAF-defined scores of activity. Patients with either significant or bridging fibrosis overwhelmingly had NASH, and bridging fibrosis most often coexisted with severe activity. CONCLUSIONS: The FLIP algorithm/SAF score, although based on purely morphological grounds, are clinically relevant, as they identify patients with distinct clinical and biological profiles of disease severity. Disease activity in NAFLD is associated with fibrosis severity. LAY SUMMARY: The examination of liver tissue under the microscope (histology) serves to define the type and severity of non-alcoholic fatty liver disease morphologically, and is also used to determine improvement in therapeutic or natural history clinical trials. The FLIP algorithm/SAF classification is a new histological classification well validated on morphological but not clinical grounds. Here, we demonstrate that different disease categories defined by the FLIP/SAF classification correspond to entities of different clinical and biological severity. We also show a strong association between the activity of steatohepatitis (defined histologically) and the amount of fibrotic scar.

Evaluation of diffusion kurtosis imaging in stratification of nonalcoholic fatty liver disease and early diagnosis of nonalcoholic steatohepatitis in a rabbit model.

PURPOSE: To examine the feasibility of MR diffusion kurtosis imaging (DKI) for characterizing nonalcoholic fatty liver disease (NAFLD) and diagnosing nonalcoholic steatohepatitis (NASH). METHODS: Thirty-two rabbits on high fat diet with different severities of NAFLD were imaged at 3 T MR including diffusion weighted imaging (DWI) and DKI using b values of 0, 400, 800 s/mm2 with 15 diffusion directions at each b value. Apparent diffusion coefficient (ADC) was derived from the linear exponential DWI model. Mean diffusion (MD) and mean kurtosis (MK) were derived from the quadratic exponential model of DKI. Correlations between MR parameters and hepatic pathology determined by the NAFLD activity scoring system were analyzed by Spearman rank correlation analysis. Receiver operating characteristic analyses were applied to determine the cutoff values of MD, MK as well as ADC in distinguishing NASH from non-NASH. The diagnostic efficacies of MD and MK in detecting NASH were compared with that of ADC. RESULTS: Values for ADC and MD significantly decreased as the severity of NAFLD increased (ρ = -0.529, -0.904, respectively; P < 0.05). MK values significantly increased as the severity of NAFLD increased (ρ = 0.761; P < 0.05). In addition, both MD and MK values were significantly different between borderline NASH and NASH groups (MD: 1.729 ±â€¯0.144 vs. 1.458 ±â€¯0.240[×10-3 mm2/s]; MK: 1.096 ±â€¯0.079 vs. 1.237 ±â€¯0.180; P < 0.05). Moreover, there was a significantly higher area under the curve (AUC) for both MD (0.955) and MK (0.905), as compared to ADC (0.736). CONCLUSION: Diffusion kurtosis imaging was feasible for stratifying NAFLD, and more accurately discriminated NASH from non-NASH when compared with DWI.

The grade of nonalcoholic fatty liver disease is an independent risk factor for gallstone disease: An observational Study.

There have been reports linking nonalcoholic fatty liver disease (NAFLD) with gallstone disease (GD) owing to shared risk factors. However, there are no reported associations between the different NAFLD grades and GD. This study aimed to determine whether NAFLD grade is an independent risk factor for GD in a Korean population.This study enrolled 7886 participants who completed a questionnaire and underwent medical examination and ultrasound scanning at the Health Promotion Center of Jeju National University Hospital in Korea, from January 2009 to December 2017. Fatty liver grading and presence of gallstones were investigated using abdominal ultrasound. Body mass index and biochemical parameters were measured, and age, sex, and metabolic syndrome status were collected from medical records. Univariate and multivariate analyses were performed to identify risk factors for GD.The estimated prevalences of NAFLD and GD were 40.6% and 4.5%, respectively. In the univariate analysis, factors associated with GD were age; NAFLD; presence of metabolic syndrome; and levels of fasting blood glucose, high-density lipoproteins, aspartate aminotransferase, and alanine aminotransferase. Multivariate logistic regression analysis revealed older age and higher NAFLD grade as independent risk factors for GD.Older age and higher grade of NAFLD were independent risk factors for GD in our cohort. There was a strong correlation between grade of NAFLD on abdominal ultrasonography and GD.

Relation of Hepatic Fibrosis in Nonalcoholic Fatty Liver Disease to Left Ventricular Diastolic Function and Exercise Tolerance.

The purpose of this study was to determine the relation between liver histology, exercise tolerance, and diastolic function in patients with nonalcoholic fatty liver disease (NAFLD). Myocardial remodeling and diastolic dysfunction have been associated with NAFLD. However, its physiological impact and relationship to the histological severity of NAFLD is not known. Cardiopulmonary exercise testing and stress echocardiography was performed in subjects with biopsy-confirmed NAFLD. Maximal aerobic exercise capacity (peak oxygen consumption [VO2]) was related to diastolic function (mitral annulus Doppler velocity e' and ratio of early diastolic filling pressure [E] to e' [E/e']) at rest and peak exercise. Autonomic dysfunction was determined from heart rate recovery after exercise. Independent predictors of cardiac function and exercise capacity were identified by multivariable regression. Thirty-six subjects (nonalcoholic fatty liver [NAFL  =  15], nonalcoholic steatohepatitis [NASH  =  21]) were enrolled. NASH was associated with impaired exercise capacity compared with NAFL (median peak VO2 17.0 [15.4, 18.9] vs 19.9 [17.4, 26.0], p  =  001); pVO2 declined with increasing fibrosis (F0  =  22.5, F1  =  19.9, F2  =  19.0, F3  =  16.6 ml·kg-1·min-1; p  =  0.01). Similarly, E/e' during exercise increased progressively with increasing fibrosis (F0  =  5.6, F1  =  6.5, F2  =  8.7, F3  =  9.8; P  =  0.02). Finally, heart rate recovery, a marker of autonomic function, was blunted in those with higher fibrosis stages (F0  =  25 [20, 30], F1  =  23 [17.5, 27.0], F2  =  17 [11.8, 21.5], F3  =  11 [8.5, 18.0] beats per minute; p <0.01). Fibrosis was an independent predictor of these functional outcomes. In conclusion, NASH is associated with impaired exercise capacity and diastolic dysfunction compared with NAFL. The severity of impairment is directly related to the severity of fibrosis stage in precirrhotic stages of NAFLD.

Mapping the triglyceride distribution in NAFLD human liver by MALDI imaging mass spectrometry reveals molecular differences in micro and macro steatosis.

Hepatic lipid accumulation, mainly in the form of triglycerides (TGs), is the hallmark of non-alcoholic fatty liver disease (NAFLD). To date, the spatial distribution of individual lipids in NAFLD-affected livers is not well characterized. This study aims to map the triglyceride distribution in normal human liver samples and livers with NAFLD and cirrhosis with imaging mass spectrometry (MALDI IMS). Specifically, whether individual triglyceride species differing by fatty acid chain length and degree of saturation correlate with the histopathological features of NAFLD as identified with classical H&E. Using a recently reported sodium-doped gold-assisted laser desorption/ionization IMS sample preparation, 20 human liver samples (five normal livers, five samples with simple steatosis, five samples with steatohepatitis, and five samples with cirrhosis) were analyzed at 10-µm lateral resolution. A total of 24 individual lipid species, primarily neutral lipids, were identified (22 TGs and two phospholipids). In samples with a low level of steatosis, TGs accumulated around the pericentral zone. In all samples, TGs with different degrees of side-chain saturation and side-chain length demonstrated differential distribution. Furthermore, hepatocytes containing macro lipid droplets were highly enriched in fully saturated triglycerides. This enrichment was also observed in areas of hepatocyte ballooning in samples with steatohepatitis and cirrhosis. In conclusion, macro lipid droplets in NAFLD are enriched in fully saturated triglycerides, indicating a possible increase in de novo lipogenesis that leads to steatohepatitis and cirrhosis.