Lean-non-alcoholic fatty liver disease increases risk for metabolic disorders in a normal weight Chinese population

Natural History of Nonalcoholic Fatty Liver Disease With Normal Body Mass Index: A Population-Based Study

BACKGROUND & AIMS

The natural history of lean nonalcoholic fatty liver disease (NAFLD) is not well-understood. Consequently, patient counseling and disease management are limited. We aimed to compare the natural history of lean, overweight, and obese NAFLD in a U.S. population with long-term follow-up.

METHODS

All adults diagnosed with NAFLD in Olmsted County, MN between 1996 and 2016 were identified, and all subsequent medical events were ascertained using a medical record linkage system. Subjects were divided on the basis of body mass index (BMI) at NAFLD diagnosis into 3 groups: normal, overweight, and obese. The probability to develop cirrhosis, decompensation, malignancies, cardiovascular events, or death among the 3 groups was estimated by using the Aalen-Johansen method, treating death as a competing risk. The impact of BMI categories on these outcomes was explored by using Cox proportional hazards regression analysis.

RESULTS

A total of 4834 NAFLD individuals were identified: 414 normal BMI, 1189 overweight, and 3231 obese. Normal BMI NAFLD individuals were characterized by a higher proportion of women (66% vs 47%) and lower prevalence of metabolic comorbidities than the other 2 groups. In reference to obese, those with normal BMI NAFLD had a nonsignificant trend toward lower risk of cirrhosis (hazard ratio [HR], 0.33, 95% confidence interval [CI], 0.1-1.05). There were no significant differences in the risk of decompensation (HR, 0.79; 95% CI, 0.11-5.79), cardiovascular events (HR, 1.05; 95% CI, 0.73-1.51), or malignancy (HR, 0.87; 95% CI, 0.51-1.48). Compared with obese, normal BMI NAFLD had higher risk of all-cause mortality (HR, 1.96; 95% CI, 1.52-2.51).

CONCLUSIONS

NAFLD with normal BMI is associated with a healthier metabolic profile and possibly a lower risk of liver disease progression but similar risk of cardiovascular disease and malignancy than obese NAFLD.

Macrophage SCAP Contributes to Metaflammation and Lean NAFLD by Activating STING-NF-κB Signaling Pathway

BACKGROUND & AIMS

Sterol regulatory element binding protein cleavage-activating protein (SCAP) is a cholesterol sensor that confers a broad range of functional effects in metabolic diseases. Lean nonalcoholic fatty liver disease (NAFLD) is characterized by a decrease in subcutaneous fat and ectopic fat deposition in the liver. SCAP may mediate the development of lean NAFLD, but the mechanism of action remains unclear.

METHODS

C57BL/6J wild-type and macrophage SCAP-specific knockout mice (SCAP^ΔMϕ) were subjected to Paigen diet (PD) feeding induced lean NAFLD. Inflammation and lipid metabolism of adipose and liver were evaluated. The STING-NF-κB signaling pathway was examined in vivo and in vitro to explore the underlying mechanism of macrophage SCAP on metaflammation.

RESULTS

The data showed heterogeneity of lipid metabolic processes in liver and epididymal white adipose tissue due to inflammation mediated by macrophage infiltration. Meanwhile, we found that the macrophage SCAP was abnormally increased in the adipose and liver tissues of PD-fed mice. Intriguingly, the SCAP^ΔMϕ mice attenuated PD-induced metaflammation and ectopic lipid deposition by reducing hepatic stimulator of interferon gene (STING)-nuclear factor kappa B (NF-κB) pathway activation. In-depth molecular analysis revealed that SCAP specifically recruits the STING and tank-binding kinase 1 onto the Golgi to activate the NF-κB in macrophages, thereby promoting the release of inflammatory factors. This process ultimately led to an increased lipolysis in adipocytes and lipid uptake and synthesis in hepatocytes.

CONCLUSIONS

Our findings suggest that SCAP acts as a novel regulator of the macrophage inflammatory response and the pathogenesis of lean NAFLD by activating the STING-NF-κB signaling pathway. Inhibition of macrophage SCAP may represent a new therapeutic strategy for the treatment of lean NAFLD.

NAFLD in normal weight individuals

Nonalcoholic fatty liver disease (NAFLD) can develop in lean individuals. Despite a better metabolic profile, the risk of disease progression to hepatic inflammation, fibrosis, and decompensated cirrhosis in the lean is similar to that in obesity-related NAFLD and lean individuals may experience more severe hepatic consequences and higher mortality relative to those with a higher body mass index (BMI). In the absence of early symptoms and abnormal laboratory findings, lean individuals are not likely to be screened for NAFLD or related comorbidities; however, given the progressive nature of the disease and the increased risk of morbidity and mortality, a clearer understanding of the natural history of NAFLD in lean individuals, as well as efforts to raise awareness of the potential health risks of NAFLD in lean individuals, are warranted. In this review, we summarize available data on NAFLD prevalence, clinical characteristics, outcomes, and mortality in lean individuals and discuss factors that may contribute to the development of NAFLD in this population, including links between dietary and genetic factors, menopausal status, and ethnicity. We also highlight the need for greater representation of lean individuals in NAFLD-related clinical trials, as well as more studies to better characterize lean NAFLD, develop improved screening algorithms, and determine specific treatment strategies based on underlying etiology.

The National Consensus statement on the management of adult patients with non-alcoholic fatty liver disease and main comorbidities

The National Consensus was prepared with the participation of the National Medical Association for the Study of the Multimorbidity, Russian Scientific Liver Society, Russian Association of Endocrinologists, Russian Association of Gerontologists and Geriatricians, National Society for Preventive Cardiology, Professional Foundation for the Promotion of Medicine Fund PROFMEDFORUM. The aim of the multidisciplinary consensus is a detailed analysis of the course of non-alcoholic fatty liver disease (NAFLD) and the main associated conditions. The definition of NAFLD is given, its prevalence is described, methods for diagnosing its components such as steatosis, inflammation and fibrosis are described. The association of NAFLD with a number of cardio-metabolic diseases (arterial hypertension, atherosclerosis, thrombotic complications, type 2 diabetes mellitus (T2DM), obesity, dyslipidemia, etc.), chronic kidney disease (CKD) and the risk of developing hepatocellular cancer (HCC) were analyzed. The review of non-drug methods of treatment of NAFLD and modern opportunities of pharmacotherapy are presented. The possibilities of new molecules in the treatment of NAFLD are considered: agonists of nuclear receptors, antagonists of pro-inflammatory molecules, etc. The positive properties and disadvantages of currently used drugs (vitamin E, thiazolidinediones, etc.) are described. Special attention is paid to the multi-target ursodeoxycholic acid (UDCA) molecule in the complex treatment of NAFLD as a multifactorial disease. Its anti-inflammatory, anti-oxidant and cytoprotective properties, the ability to reduce steatosis an independent risk factor for the development of cardiovascular pathology, reduce inflammation and hepatic fibrosis through the modulation of autophagy are considered. The ability of UDCA to influence glucose and lipid homeostasis and to have an anticarcinogenic effect has been demonstrated. The Consensus statement has advanced provisions for practitioners to optimize the diagnosis and treatment of NAFLD and related common pathogenetic links of cardio-metabolic diseases.

Prevalence and Risk Factors of Metabolic-Associated Fatty Liver Disease among 73,566 Individuals in Beijing, China

The prevalence of metabolic-associated fatty liver disease (MAFLD) is rarely reported in Beijing. The goal of this study was to estimate the prevalence and risk factors of MAFLD among Beijing adults aged ≥25 years old. A cross-sectional, community-based survey with multistage stratified cluster sampling was used. Demographic, transient elastography (TE), biochemical and blood examination information was collected in all the subjects in this study. The prevalence of MAFLD was 32.40% (23,832/73,566). Risk factors independently associated with MAFLD included male gender (OR = 1.47, 95%CI, 1.43–1.52), urban residence (OR = 1.06, 95% CI, 1.02–1.10), older age (30–39 years: OR = 1.29; 40–49 years: OR = 1.43; 50–59 years: OR = 1.09; ≥60 years: OR = 1.52) and lower education (middle school: OR = 2.03; high school: OR = 1.89; undergraduate: OR = 1.69). MAFLD was more common in females than in males after 50 years of age. Lean/normal weight MAFLD patients account for approximately 3.04% (724/23,832) of MAFLD. Compared to non-MAFLD subjects, the lean/normal MAFLD patients had a higher prevalence of hypertension and diabetes, and had a higher degree of hepatic steatosis and liver function enzymology parameters (all p < 0.001). MAFLD was highly prevalent among the general population aged ≥25 years old in Beijing. MAFLD was closely associated with male gender, older age, lower education and urban residence. Even lean/normal-weight people were under risk of MAFLD.

Nonalcoholic Fatty Liver Disease Is a Precursor of New-Onset Metabolic Syndrome in Metabolically Healthy Young Adults

Nonalcoholic fatty liver disease (NAFLD) is associated with metabolic syndrome (MetS). However, the temporal relationship between NAFLD and MetS has yet to be evaluated, especially in young adults. In this study, we investigated whether NAFLD could be a precursor for MetS in metabolically healthy young adults. Using the Korean nationwide health screening database, we analyzed subjects aged 20–39 years who were free from any component of MetS between 2009 and 2012. A total of 1,659,192 subjects without excessive alcohol consumption or concomitant liver disease were categorized into three groups according to the fatty liver index (FLI): (1) NAFLD (FLI ≥ 60); (2) borderline NAFLD (30 ≤ FLI < 60); and (3) control (FLI < 30). During the 6,699,462 person-years of follow-up, 109,239 subjects developed MetS (16.3 per 1000-person-years). The NAFLD group and the borderline NAFLD group were associated with a higher risk of MetS than the control group (incidence rate ratios, 2.9 (95% confidence interval (CI), 2.7–3.1) for the NAFLD group and 2.1 (95% CI, 2.1–2.2) for the borderline NAFLD group, respectively). In addition, all of the metabolic components were positively associated with FLI in a proportional manner. NAFLD is associated with the future onset of MetS in young adults. Therefore, active lifestyle intervention is required for young adults diagnosed with NAFLD to prevent MetS and other metabolic diseases.

Hesperidin suppresses ERS-induced inflammation in the pathogenesis of non-alcoholic fatty liver disease

Objective: The current study aimed to establish a non-alcoholic fatty liver disease (NAFLD) model using HFD-fed SD rats and FFA-stimulated human THP-1 cells to examine whether hesperidin (HSP) plays a role in endoplasmic reticulum stress (ERS)-induced inflammation in the pathogenesis of NAFLD.

Methods: Oil red O staining was used to determine the effect of HSP on hepatic steatosis in rat liver tissues. Differentially expressed genes (DEGs) were subjected to functional enrichment analysis by bioinformatics. Western blotting was used to detect the protein expression of GRP94, ATF6, ATF4, p-PERK, p-IRE1α, IL-1β, IL-6, and TNF-α in liver tissues and THP-1 cell lines, and the expression of GRP94 and p-PERK in vitro was detected through immunofluorescence staining.

Results: HSP significantly decreased the weight gain, hepatic steatosis but not serum lipid profile and suppressed the serum levels of inflammatory factors in HFD-fed rats. It was revealed by bioinformatics analysis that the inflammatory response and IRE1α activation were enriched signaling pathways in NAFLD. The expression of ERS-related biomarkers, GRP94, ATF6, ATF4, p-PERK and p- IRE1α, was significantly suppressed by HSP in vivo and in vitro. Moreover, the inflammatory markers, including IL-1β, IL-6, and TNF-α, were also decreased by HSP in vivo and in vitro. Immunofluorescence staining exposed that the expression of GRP94 and p-PERK was decreased by HSP in vitro.

Conclusion: HSP may suppress ERS-induced inflammation in the pathogenesis of NAFLD.

Caucasian lean subjects with non-alcoholic fatty liver disease share long-term prognosis of non-lean: time for reappraisal of BMI-driven approach?

OBJECTIVE

The full phenotypic expression of non-alcoholic fatty liver disease (NAFLD) in lean subjects is incompletely characterised. We aimed to investigate prevalence, characteristics and long-term prognosis of Caucasian lean subjects with NAFLD.

DESIGN

The study cohort comprises 1339 biopsy-proven NAFLD subjects from four countries (Italy, UK, Spain and Australia), stratified into lean and non-lean (body mass index (BMI)

RESULTS

Lean patients represented 14.4% of the cohort and were predominantly of Italian origin (89%). They had less severe histological disease (lean vs non-lean: non-alcoholic steatohepatitis 54.1% vs 71.2% p<0.001; advanced fibrosis 10.1% vs 25.2% p<0.001), lower prevalence of diabetes (9.2% vs 31.4%, p<0.001), but no significant differences in the prevalence of the PNPLA3 I148M variant (p=0.57). During a median follow-up of 94 months (>10 483 person-years), 4.7% of lean vs 7.7% of non-lean patients reported liver-related events (p=0.37). No difference in survival was observed compared with non-lean NAFLD (p=0.069).

CONCLUSIONS

Caucasian lean subjects with NAFLD may progress to advanced liver disease, develop metabolic comorbidities and experience cardiovascular disease (CVD) as well as liver-related mortality, independent of longitudinal progression to obesity and PNPLA3 genotype. These patients represent one end of a wide spectrum of phenotypic expression of NAFLD where the disease manifests at lower overall BMI thresholds.

LAY SUMMARY

NAFLD may affect and progress in both obese and lean individuals. Lean subjects are predominantly males, have a younger age at diagnosis and are more prevalent in some geographic areas. During the follow-up, lean subjects can develop hepatic and extrahepatic disease, including metabolic comorbidities, in the absence of weight gain. These patients represent one end of a wide spectrum of phenotypic expression of NAFLD.

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Key Words

• fatty liver
• nonalcoholic steatohepatitis

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MESH Headings

• Adult
• Body Mass Index
• Cohort Studies
• Female
• Humans
• Male
• Middle Aged
• Non-alcoholic Fatty Liver Disease/complications
• Non-alcoholic Fatty Liver Disease/mortality
• Non-alcoholic Fatty Liver Disease/pathology
• Prognosis
• Survival Rate
• Thinness/complications
• Thinness/mortality
• Thinness/pathology
• White People

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Grants

• MR/N005872/1 Medical Research Council

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Affiliation(s)

Ramy Younes The Newcastle Liver Research Group, Translational & Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK Boehringer Ingelheim International GmbH, Ingelheim, Germany Department of Medical Sciences, Division of Gastroenterology and Hepatology, A.O. Città della Salute e della Scienza di Torino, Università degli Studi di Torino, Torino, Italy
Olivier Govaere The Newcastle Liver Research Group, Translational & Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
Salvatore Petta Sezione di Gastroenterologia, PROMISE, Università di Palermo, Palermo, Italy
Luca Miele Dipartimento Universitario Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy Area Medicina Interna, Gastroenterologia e Oncologia Medica, Fondazione Policlinico A. Gemelli IRCCS, Rome, Italy
Dina Tiniakos The Newcastle Liver Research Group, Translational & Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK Dept of Pathology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
Alastair Burt The Newcastle Liver Research Group, Translational & Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
Ezio David Department of Medical Sciences, Division of Gastroenterology and Hepatology, A.O. Città della Salute e della Scienza di Torino, Università degli Studi di Torino, Torino, Italy
Fabio Maria Vecchio Dipartimento Universitario Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy Area Anatomia Patologica, Fondazione Policlinico Gemelli IRCCS, Rome, Italy
Marco Maggioni Department of Pathology, Ca' Granda IRCCS Foundation, Milan, Italy
Daniela Cabibi Pathology Institute, PROMISE, University of Palermo, Palermo, Italy
Duncan McLeod Department of Anatomical Pathology, Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, Sydney, New South Wales, Australia
Maria Jesus Pareja Pathology Unit, Hospital Universitario de Valme, Sevilla, Spain
Anna Ludovica Fracanzani Unit of Medicine and Metabolic Disease Ca' Granda IRCCS Foundation, Policlinico Hospital, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
Rocio Aller Gastroenterology, Hospital Clínico Universitario de Valladolid, Centro de Investigación de Endocrinología y Nutrición, Universidad de Valladolid, Valladolid, Spain
Chiara Rosso Department of Medical Sciences, Division of Gastroenterology and Hepatology, A.O. Città della Salute e della Scienza di Torino, Università degli Studi di Torino, Torino, Italy
Javier Ampuero UCM Digestive Diseases and SeLiver Group, Virgen del Rocio University Hospital, Institute of Biomedicine of Seville, University of Seville, Seville, Spain
Rocío Gallego-Durán UCM Digestive Diseases and SeLiver Group, Virgen del Rocio University Hospital, Institute of Biomedicine of Seville, University of Seville, Seville, Spain
Angelo Armandi Department of Medical Sciences, Division of Gastroenterology and Hepatology, A.O. Città della Salute e della Scienza di Torino, Università degli Studi di Torino, Torino, Italy
Gian Paolo Caviglia Department of Medical Sciences, Division of Gastroenterology and Hepatology, A.O. Città della Salute e della Scienza di Torino, Università degli Studi di Torino, Torino, Italy
Marco Y W Zaki The Newcastle Liver Research Group, Translational & Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK Biochemistry Department, Faculty of Pharmacy, Minia University, El Minia, Egypt
Antonio Liguori Dipartimento Universitario Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy
Paolo Francione Unit of Medicine and Metabolic Disease Ca' Granda IRCCS Foundation, Policlinico Hospital, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
Grazia Pennisi Sezione di Gastroenterologia, PROMISE, Università di Palermo, Palermo, Italy
Antonio Grieco Dipartimento Universitario Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy Area Medicina Interna, Gastroenterologia e Oncologia Medica, Fondazione Policlinico A. Gemelli IRCCS, Rome, Italy
Giovanni Birolo Department of Medical Sciences, Division of Gastroenterology and Hepatology, A.O. Città della Salute e della Scienza di Torino, Università degli Studi di Torino, Torino, Italy
Piero Fariselli Department of Medical Sciences, Division of Gastroenterology and Hepatology, A.O. Città della Salute e della Scienza di Torino, Università degli Studi di Torino, Torino, Italy
Mohammed Eslam Storr Liver Centre, Westmead Institute for Medical Research, Westmead Hospital and University of Sydney, Westmead, New South Wales, Australia
Luca Valenti Translational Medicine, Department of Transfusion Medicine and Hematology, Fondazione IRCCS C'a Granda Ospedale Maggiore Policlinico, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
Jacob George Storr Liver Centre, Westmead Institute for Medical Research, Westmead Hospital and University of Sydney, Westmead, New South Wales, Australia
Manuel Romero-Gómez UCM Digestive Diseases and SeLiver Group, Virgen del Rocio University Hospital, Institute of Biomedicine of Seville, University of Seville, Seville, Spain
Quentin Mark Anstee The Newcastle Liver Research Group, Translational & Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK Newcastle NIHR Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
Elisabetta Bugianesi Department of Medical Sciences, Division of Gastroenterology and Hepatology, A.O. Città della Salute e della Scienza di Torino, Università degli Studi di Torino, Torino, Italy

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Collaborators Collapse

S2FLNet: Hepatic steatosis detection network with body shape

Fat accumulation in the liver cells can increase the risk of cardiac complications and cardiovascular disease mortality. Therefore, a way to quickly and accurately detect hepatic steatosis is critically important. However, current methods, e.g., liver biopsy, magnetic resonance imaging, and computerized tomography scan, are subject to high cost and/or medical complications. In this paper, we propose a deep neural network to estimate the degree of hepatic steatosis (low, mid, high) using only body shapes. The proposed network adopts dilated residual network blocks to extract refined features of input body shape maps by expanding the receptive field. Furthermore, to classify the degree of steatosis more accurately, we create a hybrid of the center loss and cross entropy loss to compact intra-class variations and separate inter-class differences. We performed extensive tests on the public medical dataset with various network parameters. Our experimental results show that the proposed network achieves a total accuracy of over 82% and offers an accurate and accessible assessment for hepatic steatosis.

Role of aerobic exercise in ameliorating NASH: Insights into the hepatic thyroid hormone signaling and circulating thyroid hormones

AIM

Triiodothyronine (T3) administration significantly eliminates hepatic steatosis and also has a therapeutic effect on non-alcoholic steatohepatitis (NASH). However, the potential mechanism by which T3-mediated exercise improves NASH is unknow. This study aimed to explore the effect of aerobic exercise on liver injury in NASH.

METHODS

Aerobic exercise was conducted to explore the effects of exercise on liver injury in NASH model induced by Atherosclerotic (Ath) diet. Biochemical evaluations, histological staining and real-time PCR were first applied to confirm the amelioration effects of exercise on NASH. RNA-sequencing (RNA-seq) analysis for livers of each group were further used to identify the underlying mechanisms of aerobic exercise. Bioinformatics methods were used to explore the key functional pathways involved in the improvement of liver tissue in NASH mice by aerobic exercise.

RESULTS

Aerobic exercise improved hepatic steatosis, lobular inflammation and fibrosis in NASH mice. multiple inflammation-related pathways were significantly enriched in the liver of NASH group and improved by aerobic exercise. The results of gene set variation analysis (GSVA) showed a higher enrichment score of T3 response signature in NASH mice with exercise. Increased Dio1 expression in the liver of NASH with exercise mice and increased circulating FT3 and FT4 levels upon aerobic exercise were confirmed.

CONCLUSIONS

We found that aerobic exercise could significantly reduce hepatic lipid accumulation, inflammatory infiltration and fibrosis progression in the liver of NASH mice. Hepatic thyroid hormone signaling activation and circulating thyroid hormones is potentially involved in the amelioration effect of aerobatic exercise on NASH progression.

The Association of Sarcopenia and Visceral Obesity with Lean Nonalcoholic Fatty Liver Disease in Chinese Patients with Type 2 Diabetes Mellitus

BACKGROUND

Few studies have specifically observed the relationship of sarcopenia, visceral obesity, or their joint effects with lean NAFLD in patients with diabetes. We aimed to investigate the associations of lean NAFLD with sarcopenia, visceral obesity, and sarcopenic visceral obesity (SV) in Chinese patients with type 2 diabetes mellitus (T2DM).

METHODS

Altogether, 1,112 T2DM patients with BMI <25 kg/m² were enrolled, and 33.18% of them were diagnosed with lean NAFLD by abdominal ultrasonography. Body composition markers were measured by bioelectrical impedance (BIA). Skeletal muscle mass index (SMI) was calculated as appendicular skeletal muscle mass (ASM) divided by weight, and sarcopenia was defined as SMI < 1 standard deviation (SD) below the sex-specific average for a young reference population. Visceral obesity was defined as visceral fat area (VFA) ≥ 100 cm². Participants were categorized into one of the four body composition groups: nonsarcopenia/nonvisceral obesity (NN), nonsarcopenia/visceral obesity (NV), sarcopenia/nonvisceral obesity (SN), and SV.

RESULTS

Compared to those in the NN group, patients in the NV and SN groups had a higher risk of lean NAFLD after full adjustments (NV: OR = 1.74; 95% CI: 1.09, 2.78; SN: OR =2.07; 95% CI: 1.23, 3.46). Of note, patients in the SV group had the highest odds of lean NAFLD (OR = 3.29; 95% CI: 2.10, 5.17). There were no significant interaction effects between sarcopenia and metabolic risk factors on prevalent lean NAFLD.

CONCLUSIONS

The current study demonstrated that SV was more closely associated with higher prevalent lean NAFLD than sarcopenia or visceral obesity alone in Chinese patients with T2DM. Besides, the harmful effect of sarcopenia on lean NAFLD was not influenced by visceral obesity or other metabolic risk factors. We hypothesize that increasing skeletal muscle mass more than just reducing visceral fat might be more optimal for the prevention and management of lean NAFLD, which needs further investigation in future studies.

The Visceral Adiposity Index in Non-Alcoholic Fatty Liver Disease and Liver Fibrosis-Systematic Review and Meta-Analysis

(1) Background: In order to avoid a liver biopsy in non-alcoholic fatty liver disease (NAFLD), several noninvasive biomarkers have been studied lately. Therefore, we aimed to evaluate the visceral adiposity index (VAI) in NAFLD and liver fibrosis, in addition to its accuracy in predicting NAFLD and NASH. (2) Methods: We searched PubMed, Embase, Scopus, and Cochrane Library, identifying observational studies assessing the VAI in NAFLD and liver fibrosis. QUADAS-2 was used to evaluate the quality of included studies. The principal summary outcomes were mean difference (MD) and area under the curve (AUC). (3) Results: A total of 24 studies were included in our review. VAI levels were significantly increased in NAFLD (biopsy-proven and ultrasound-diagnosed), simple steatosis vs. controls, and severe steatosis vs. simple steatosis. However, no significant MD was found according to sex, liver fibrosis severity, simple vs. moderate and moderate vs. severe steatosis, pediatric NAFLD, and NASH patients. The VAI predicted NAFLD (AUC 0.767) and NASH (AUC 0.732). (4) Conclusions: The VAI has a predictive value in diagnosing NAFLD and NASH, with significantly increased values in adult NAFLD patients, simple steatosis compared to controls, and severe steatosis compared to simple steatosis.

Visceral adiposity as a risk factor for lean non-alcoholic fatty liver disease in potential living liver donors

BACKGROUND AND AIM

This study aimed to investigate the relationship between hepatic steatosis (HS) evaluated by biopsy and visceral adiposity assessed by computed tomography in lean living liver donor candidates and to determine the risk factors for lean non-alcoholic fatty liver disease (NAFLD).

METHODS

This retrospective study included 250 lean (body mass index, < 23 kg/m² ) potential living liver donors (mean age, 31.1 ± 8.6 years; 141 men) who had undergone liver biopsy and abdominal computed tomography between 2017 and 2018. Anthropometry, laboratory parameters, body composition, and the degree of HS were evaluated. Logistic regression was used to identify independent predictors of lean NAFLD.

RESULTS

The visceral fat area (VFA) was significantly correlated with the degree of HS in men (r = 0.408; P < 0.001) and women (r = 0.360; P < 0.001). The subcutaneous fat area was significantly correlated with the degree of HS in men (r = 0.398; P < 0.001), but not in women. The skeletal muscle area did not correlate with the degree of HS in either men or women. In the multivariable logistic regression analysis, the VFA (odds ratio [OR], 1.028; 95% confidence interval [CI], 1.013-1.044; P < 0.001) and subcutaneous fat area (OR, 1.016; 95% CI, 1.004-1.028; P = 0.009) were independent risk factors for lean NAFLD in men, and the VFA (OR, 1.036; 95% CI, 1.013-1.059; P = 0.002) was an independent risk factor for lean NAFLD in women.

CONCLUSIONS

The severity of non-alcoholic fatty liver was positively correlated with visceral fat accumulation in a lean Asian population. Visceral adiposity may be a risk factor for lean NAFLD in potential living liver donors.

Non-Alcoholic Fatty Liver Disease in Lean and Non-Obese Individuals: Current and Future Challenges

Non-alcoholic fatty liver disease (NAFLD), which approximately affects a quarter of the world’s population, has become a major public health concern. Although usually associated with excess body weight, it may also affect normal-weight individuals, a condition termed as lean/non-obese NAFLD. The prevalence of lean/non-obese NAFLD is around 20% within the NAFLD population, and 5% within the general population. Recent data suggest that individuals with lean NAFLD, despite the absence of obesity, exhibit similar cardiovascular- and cancer-related mortality compared to obese NAFLD individuals and increased all-cause mortality risk. Lean and obese NAFLD individuals share several metabolic abnormalities, but present dissimilarities in genetic predisposition, body composition, gut microbiota, and susceptibility to environmental factors. Current treatment of lean NAFLD is aimed at improving overall fitness and decreasing visceral adiposity, with weight loss strategies being the cornerstone of treatment. Moreover, several drugs including PPAR agonists, SGLT2 inhibitors, or GLP-1 receptor agonists could also be useful in the management of lean NAFLD. Although there has been an increase in research regarding lean NAFLD, there are still more questions than answers. There are several potential drugs for NAFLD therapy, but clinical trials are needed to evaluate their efficacy in lean individuals.

Negative interaction of fatty liver and hypertension on cardiovascular mortality in non-diabetic men: 34 years of follow-up

BACKGROUND AND OBJECTIVES

Fatty liver disease (FLD) and hypertension are separately associated with cardiovascular (CV) mortality. The two conditions are related in multiple ways. This work aimed to study the joint effect and interaction of FLD and hypertension in respect to overall and CV mortality.

METHODS

The population-based cohort, Kuopio Ischaemic Disease Risk Factor Study, followed 1569 middle-aged non-diabetic Finnish men for 34 years. Considering adjustment for age, body mass index, smoking and alcohol consumption, separate and combined effects of FLD and hypertension and their interaction at the multiplicative and additive scales regarding all-cause and CV death were assessed using Cox proportional hazards models.

RESULTS

FLD and hypertension coexisted in 8.54% of the men (n = 134). FLD and hypertension associated, independently and combined, with an increased hazard of all-cause and CV deaths. Non-CV mortality associated with FLD, but not with hypertension. We found a negative interaction between FLD and hypertension regarding the hazard of all-cause (relative excess risk due to interaction (RERI), -0.97; 95% confidence interval (CI), -1.65 to -0.28) and CV mortality (RERI, -1.74; 95% CI, -2.98 to -0.5). The interaction was also found on a multiplicative scale.

CONCLUSIONS

We found evidence of a negative interaction between FLD and hypertension in respect to CV mortality. We thus recommend adjusting for FLD or hypertension when studying the effect of the other condition on mortality or CV diseases in middle-aged men.

Low serum Maresin-1 levels are associated with non-alcoholic fatty liver disease: a cross-sectional study

Background

Maresin-1 (MaR1) is an anti-inflammatory pro-resolving mediator and is considered a potential regulator of metabolic diseases. Non-alcoholic fatty liver disease (NAFLD) is a very common metabolic liver disease. However, little information is available on the relationship between MaR1 and NAFLD in humans. Therefore, the study explored the association between serum MaR1 levels and NAFLD.

Methods

A cross-sectional study was conducted in 240 Chinese people, including 116 non-NAFLD subjects and 124 NAFLD patients. Serum MaR1 levels were determined by enzyme-linked immunosorbent assay (ELISA). The association between MaR1 and NAFLD was assessed.

Results

Circulating MaR1 levels in NAFLD patients were markedly lower than those in non-NAFLD subjects (63.63 [59.87–73.93] vs 73.11 [65.12–84.50] pg/mL, P = 0.000). The percentages of patients with NAFLD gradually decreased with the increase of MaR1 quartiles (P < 0.001). Furthermore, serum MaR1 levels were positively associated with aspartate aminotransferase/alanine aminotransferase (AST/ALT), albumin, the albumin-globulin-ratio, and high-density lipoprotein cholesterol (HDL-C) (all P < 0.05) and negatively associated with body mass index (BMI), waist circumference, hip circumference, the waist-to-hip ratio, ALT, gamma-glutamyl transpeptidase (GGT), uric acid, triglyceride (TG), and fasting blood glucose (FBG) (all P < 0.05) after adjusting for sex and age. Binary logistic regression analysis revealed that serum MaR1 levels were significantly associated with NAFLD.

Conclusions

Circulating MaR1 levels were decreased in patients with NAFLD, and a negative correlation was identified between NAFLD and serum MaR1 concentrations. Decreased MaR1 might be involved in the development of NAFLD.

Comparison of clinical and metabolic profiles of lean versus non-lean nonalcoholic fatty liver disease

BACKGROUND

Data on nonalcoholic fatty liver disease (NAFLD) in the Philippines are scarce. We aimed to compare the clinical and biochemical profiles of lean (BMI<23) vs. non-lean (BMI≥23) NAFLD patients.

METHODS

Consecutive patients diagnosed with NAFLD on ultrasound in two outpatient hepatology clinics from February 2007-January 2017 were included. Patients with significant alcohol intake, alternative causes of steatosis, and incomplete data were excluded.

RESULTS

A total of 663 patients (57.9% male) were included. Most patients were non-lean (88.1%) and had an elevated alanine aminotransferase (ALT) (63%). Cirrhosis or hepatocellular carcinoma (HCC) were already present in 8.4% on initial consultation. Concomitant hepatitis B was equally common in patients with and without cirrhosis (20.7% vs. 17.5%; p=0.660) or HCC (17.9% vs. 12.8%; p=0.415). Independent factors associated with HCC/cirrhosis on initial consultation were older age (OR=1.038), low albumin (OR=0.428), high BARD score (BMI, AST/ALT ratio, T2 diabetes mellitus; OR=2.548) and the presence of symptoms (OR=1.808). Compared to lean NAFLD patients, non-lean patients were more likely to be younger (51.5±14.4 vs. 55±14.3; p=0.003), have DM (47.9% vs. 29.1%; p=0.002), hypertension (57.5% vs. 38%; p=0.001), dyslipidemia (73.1% vs. 54.4%; p=0.001) and metabolic syndrome (60.3% vs. 30.4%; p<0.0001), abnormal metabolic parameters (LDL-C, HDL-C, triglycerides, uric acid and FBS), and with elevated ALT (65.2% vs. 46.8%; p=0.002) and AST (41.1±29.6 vs. 35.3±28.3; p=0.008).

CONCLUSIONS

The proportion of lean NAFLD was 11.9%. Although metabolic derangements and its clinical consequences were present in about a third of lean patients, these were still more common in non-lean NAFLD. Cirrhosis or HCC were already present in a significant proportion (8.4%) of NAFLD patients on initial presentation.

Fatal complications after an interrupted gastric bypass operation in a patient with non-alcoholic fatty liver disease and massive obesity: a case report

Obesity is closely linked to non-alcoholic fatty liver disease and non-alcoholic steatohepatitis (NASH), the latter now being the most common cause of cirrhosis in Western countries. Only a few cases have been described, such as the unexpected death after interrupted obesity surgery in a patient due to inaccurate preoperative imaging assessment. We describe a 53-year-old male patient with multiple comorbidities partly related to his obesity. A laparoscopic Roux-en-Y gastric bypass (LRYGB) was attempted. During anaesthesia, the patient had a cardiac arrhythmia and a short asystole. Intra-operative findings indicated a giant spleen and, unexpectedly, a cirrhotic liver. The LRYGB operation was interrupted. After 19 months, the patient died due to his severe comorbidities. Preoperative imaging missed the diagnosis of liver cirrhosis and related NASH. Since a challenging liver failure diagnosis cannot only rely on current imaging, we suggest that a liver biopsy is performed prior to LRYGB if preoperative imaging indicates cirrhotic liver.

Association between Visceral Adipose Tissue and Non-Alcoholic Steatohepatitis Histology in Patients with Known or Suspected Non-Alcoholic Fatty Liver Disease

(1) Purpose: To determine the association between visceral adipose tissue (VAT) and proton density fat fraction (PDFF) with magnetic resonance imaging (MRI), and hepatic steatosis (HS), non-alcoholic steatohepatitis (NASH) and hepatic fibrosis (HF) in patients with known or suspected non-alcoholic fatty liver disease (NAFLD). (2) Methods: 135 subjects that had a liver biopsy performed within 3 months (bariatric cohort) or 1 month (NAFLD cohort) of an MRI exam formed the study group. VAT volume was quantified at L2-L3 level on opposed-phase images with signal intensity-based painting using a semi-quantitative software. Liver PDFF and pancreas PDFF were calculated on fat fraction maps. Liver volume (Lvol) and spleen volume (Svol) were also calculated using a semi-automated 3D volume tool available on PACS. A histological analysis was performed by an expert hepatopathologist blinded to imaging findings. (3) Results: The mean Lvol, Svol, liver PDFF, pancreas PDFF and VAT of the study population were 2492.2 mL, 381.6 mL, 13.2%, 12.7% and 120.6 mL, respectively. VAT showed moderate correlation with liver PDFF (r = 0.41, p < 0.001) and weak correlation with Lvol (r = 0.38, p < 0.001), Svol (r = 0.20, p = 0.025) and pancreas PDFF (rs = 0.29, p = 0.001). VAT, Lvol and liver PDFF were significantly higher in patients with HS (p < 0.001), NASH (p < 0.05) and HF (p < 0.05). VAT was also significantly higher in the presence of lobular inflammation (p = 0.019) and hepatocyte ballooning (p = 0.001). The cut-off VAT volumes for predicting HS, NASH and HF were 101.8 mL (AUC, 0.7), 111.8 mL (AUC, 0.64) and 111.6 mL (AUC, 0.66), respectively. (4) Conclusion: The MRI determined VAT can be used for predicting the presence of HS, NASH and HF in patients with known or suspected NAFLD.

The association between hypertension and nonalcoholic fatty liver disease (NAFLD): literature evidence and systems biology analysis

Nonalcoholic fatty liver disease (NAFLD) has become a major public health issue as its progression increases risks of multisystem morbidity and mortality. Recent evidence indicates a more complex relationship between hypertension and NAFLD than previously thought. In this study, a comprehensive literature search was used to gather information supporting the comorbidity phenomenon of hypertension and NAFLD. Then, systems biology approach was applied to identify the potential genes and mechanisms simultaneously associated with hypertension and NAFLD. With the help of protein-protein interaction network-based algorithm, we found that the distance between hypertension and NAFLD was much less than random ones. Sixty-four shared genes of hypertension and NAFLD modules were identified as core genes. Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analysis indicated that some inflammatory, metabolic and endocrine signals were related to the potential biological functions of core genes. More importantly, drugs used to treat cardiovascular diseases, hypertension, hyperlipidemia, inflammatory diseases and depression could be potential therapeutics against hypertension-NAFLD co-occurrence. After analyzing public OMICs data, ALDH1A1 was identified as a potential therapeutic target, without being affected by reverse causality. These findings give a clue for the potential mechanisms of comorbidity of hypertension and NAFLD and highlight the multiple target-therapeutic strategy of NAFLD for future clinical research.

Lean NAFLD: an underrecognized and challenging disorder in medicine

Classically, Non-Alcoholic Fatty Liver Disease (NAFLD) has been thought to be driven by excessive weight gain and obesity. The overall greater awareness of this disorder has led to its recognition in patients with normal body mass index (BMI). Ongoing research has helped to better understand potential causes of Lean NAFLD, the risks for more advanced disease, and potential therapies. Here we review the recent literature on prevalence, risk factors, severity of disease, and potential therapeutic interventions.

Triglyceride glucose (TyG) index and the progression of liver fibrosis: A cross-sectional study

BACKGROUND

Non-alcoholic fatty liver (NAFLD) is a multi-factorial liver disease and its incidence is globally rising. Little is known about the association between triglyceride glucose (TyG) index and liver fibrosis progression in NAFLD patients.

AIM

To examine the association of liver fibrosis with TyG index among patients with NAFLD in a sample of Iranian adults.

METHODS

The NAFLD fibrosis score and the fibrosis-4 (FIB-4) index were used for the detection of hepatic fibrosis. Multivariable-adjusted odds ratios (ORs) were applied to assess the association of liver fibrosis with TyG index.

RESULTS

The current study included a total of 230 participants with NAFLD and low probability of fibrosis. The TyG index quartiles were higher in patients with higher body mass index (BMI), higher systolic blood pressure (SBP), and less physical activity than in participants with lower BMI, lower SBP and more physical activity, respectively. Moreover, higher serum levels of total cholesterol, triglyceride, LDL-C, aspartate and aminotransferases, and homeostatic model assessment for insulin resistance (HOMA-IR), and lower serum level of HDL-C were observed in patients with higher quartiles of TyG index (all P < 0.01). The severity of NAFLD significantly increased with increment in the quartiles of TyG index. Increased TyG index was positively associated with worsening of NAFLD fibrosis score and FIB-4 index. Based on NAFLD fibrosis score, the multivariable-adjusted ORs (95% CIs) were 1.98 (1.33-2.22), 2.33 (2.09-2.94), and 3.44 (2.63-4.25) in the 2nd, 3rd, and 4th quantiles of TyG index when compared to the 1st quantile of TyG index. A similar trend was observed in the analysis using FIB-4 index.

CONCLUSION

According to the results of the current study, excess TyG index contributes to the development of liver fibrosis.

Undiagnosed liver diseases

The landscape of chronic liver disease has drastically changed over the past 20 years, largely due to advances in antiviral therapy and the rise of metabolic syndrome and associated non-alcoholic fatty liver disease (NAFLD). Despite advances in the diagnosis and treatment of a variety of liver diseases, the burden of chronic liver disease is increasing worldwide. The first step to addressing any disease is accurate diagnosis. Here, we discuss liver diseases that remain undiagnosed, either because they are difficult to diagnose or due to hepatic manifestations of an unrecognized systemic disease. Additionally, their underlying etiology may remain unknown or they represent previously uncharacterized and therefore novel liver diseases. Our goal is to provide a framework for approaching undiagnosed liver diseases which elude standard hepatic diagnostic work-up and whose patterns of disease are often overlooked.

Nonalcoholic Fatty Liver Disease in Lean Subjects: Associations With Metabolic Dysregulation and Cardiovascular Risk-A Single-Center Cross-Sectional Study

INTRODUCTION

Although a milder metabolic phenotype of nonalcoholic fatty liver disease (NAFLD) in lean patients (body mass index [BMI] <25 kg/m2) compared to overweight/obese patients with NAFLD is assumed, the relevance of NAFLD among lean subjects remains a matter of debate. We aimed to characterize the metabolic/cardiovascular phenotype of lean patients with NAFLD.

METHODS

In total, 3,043 subjects (cohort I) and 1,048 subjects (cohort II) undergoing screening colonoscopy between 2010 and 2020 without chronic liver disease other than NAFLD were assigned to one of the following groups: lean patients without NAFLD, lean NAFLD, overweight NAFLD (BMI 25-30 kg/m2), and obese NAFLD (BMI >30 kg/m2). Diagnosis of NAFLD was established using ultrasound (cohort I) and controlled attenuation parameter (cohort II).

RESULTS

The prevalence of lean patients with NAFLD was 6.7%/16.1% in the overall cohort I/II and 19.7%/40.0% in lean subjects of cohort I/II. Compared with lean subjects without NAFLD, lean patients with NAFLD had a higher prevalence of dyslipidemia, dysglycemia, and the metabolic syndrome, together with a higher median Framingham risk score in both cohorts (all P < 0.001). On multivariable analyses, NAFLD in lean subjects was associated with higher odds of metabolic syndrome (adjusted odds ratio cohort I: 4.27 [95% confidence interval (CI): 2.80-6.51], P < 0.001; cohort II: 2.97 [95% CI: 1.40-6.33], P < 0.001), and higher Framingham risk score (regression coefficient B cohort I: 1.93 [95% CI: 0.95-2.92], P < 0.003; cohort II: 1.09 [95% CI: 0.81-2.10], P = 0.034), among others. Only 69.8% of lean patients with NALFD in cohort I and 52.1% in cohort II fulfilled the novel criteria for metabolic associated fatty liver disease.

DISCUSSION

NAFLD in lean patients is associated with the metabolic syndrome and increased cardiovascular risk. Novel metabolic associated fatty liver disease criteria leave a considerable proportion of patients unclassified.

Metabolically healthy obesity and metabolically obese normal weight: a review

Despite the general relationship between obesity and its co-morbidities, there are both obese individuals who scarcely present the associated pathologies (metabolically healthy obese; MHO) and individuals who present obesity alterations despite having normal weight (metabolically obese normal weight; MONW). It is still difficult to define metabolically MHO and MONW individuals because different classifications have been used in the studies reported. Indeed, different inclusion criteria have been used to discriminate between metabolically healthy and metabolically unhealthy subjects. Due to this and other reasons, such as differences in ethnicity, genetics, and lifestyle of the populations, data concerning the prevalence of MHO and MONW are very variable. The main determinants of MHO are type of growth (hypertrophy or hyperplasia), anatomical location, inflammation of adipose tissue, ectopic fat accumulation, genetic factors, and lifestyles factors. In the case of MONW, the main determinants are genetic background and lifestyle factors. With regard to treatment, it is not clear whether MHO subjects would benefit from traditional lifestyle interventions, based on diet energy restriction and increased physical activity. For MONW subjects, there is still no specialized treatment, and the therapies are the same as those used in obese subjects.

The Impact of Dietary Patterns and Nutrition in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) has become one of the most common causes of chronic liver disease worldwide. The prevalence of NAFLD has grown proportionally with the rise in obesity, sedentary lifestyle, unhealthy dietary patterns, and metabolic syndrome. Currently, in the absence of approved pharmacologic treatment, the keystone of treatment is lifestyle modification focused on achieving a weight loss of 7%-10%, cardiovascular exercise, and improving insulin sensitivity. The primary aim of this review is to outline the effect of different dietetic approaches against NAFLD and highlight the important micronutrient components in the management of NAFLD.

Implications of Abdominal Adipose Tissue Distribution on Nonalcoholic Fatty Liver Disease and Metabolic Syndrome: A Chinese General Population Study

INTRODUCTION

Visceral adipose tissue (VAT) has been found to play a critical role in the development of metabolic syndrome and nonalcoholic fatty liver disease (NAFLD) independent of generalized obesity.

METHODS

In this secondary study of prospectively acquired data, 625 participants underwent magnetic resonance spectroscopy and chemical shift fat-water separation MRI (2-point Dixon) of the liver and whole abdomen, respectively, in a 3 Tesla magnet. Whole abdominal VAT and subcutaneous adipose tissue (SAT) were extracted from the 2-point Dixon image series using an automated method. Clinical/anthropometric/blood biochemistry parameters were measured. Using region-specific body mass index, participants were classified into 3 paired subgroups (lean, overweight, and obese) and presence of NAFLD (liver fat content ≥ 5.5%).

RESULTS

All relevant clinical/anthropometric/blood biochemistry characteristics and liver enzymes were statistically significant between groups (P < 0.001). NAFLD was found in 12.1%, 43.8%, and 68.3% and metabolic syndrome in 51.1%, 61.9%, and 65% of the lean, overweight, and obese, respectively. Odds ratio for metabolic syndrome and NAFLD was increased by 2.73 (95% confidence interval [CI] 2.18-3.40) and 2.53 (95% CI 2.04-3.12), respectively, for 1SD increase in VAT volume while prevalence of metabolic syndrome was increased by 2.26 (95% CI 1.83-2.79) for 1SD increase in liver fat content (%). VAT/SAT ratio in the lean with fatty liver showed the highest ratio (0.54) among all the subgroups, without a significant difference between the lean and obese with NAFLD (P = 0.127).

DISCUSSION

Increased VAT volume/disproportional distribution of VAT/SAT may be vital drivers to the development of metabolic syndrome and NAFLD irrespective of body mass index category.

The metabolic profiles and body composition of lean metabolic associated fatty liver disease

BACKGROUND/PURPOSE

Metabolic associated fatty liver disease (MAFLD) is the commonest cause of chronic liver disease, which is associated with obesity and diabetes. However, it also occurs in lean individuals especially in Asian populations.

METHODS

The participants of Tzu Chi MAFLD cohort (TCMC) including health controls or MAFLD patients were enrolled. MAFLD was defined as fatty liver in imaging without hepatitis B virus, hepatitis C virus infection, drug, alcohol or other known causes of chronic liver disease. Lean MAFLD was defined as MAFLD in lean subjects (BMI < 23 kg/m²).

RESULTS

A total of 880 subjects were included for final analysis. Of 394 MAFLD patients, 65 (16.5%) patients were diagnosed as lean MAFLD. Lean MAFLD patients were elder, higher percentage of female gender, lower ALT, diastolic blood pressure, triglyceride, and waist circumference but higher HDL than non-lean MAFLD patients. Using binary regression analysis, elder age and lower waist circumference were associated with lean MAFLD. Compared with lean healthy controls, lean MAFLD patients had higher BMI, waist circumference, and percentage of hypertension. In body composition, fatty tissue index (FTI), lean tissue index (LTI) ,and total body water (TBW) were lower in lean MAFLD than non-lean MAFLD patients; but they were comparable with lean healthy controls.

CONCLUSIONS

The prevalence of lean MAFLD was 16.5% in this study population and it was higher in elder age, especially of female subjects. Lean MAFLD patients had different metabolic profiles compared with lean healthy controls, but different body composition compared with non-lean MAFLD patients.

Shifting perspectives - interplay between non-alcoholic fatty liver disease and insulin resistance in lean individuals

Non-alcoholic fatty liver disease (NAFLD) has become a significant public health burden affecting not only obese individuals but also people with normal weight. As opposed to previous beliefs, this particular subset of patients has an increased risk of all-cause mortality and worse outcomes than their obese counterparts. The development of NAFLD in lean subjects seems to be interconnected with metabolic phenotype, precisely visceral fat tissue, sarcopenia, and insulin resistance. Here, we summarize available data focusing on the co-dependent relationship between metabolic phenotype, insulin resistance, and development of NAFLD in lean individuals, suggesting more appropriate tools for measuring body fat distribution for the screening of patients at risk.

Nonalcoholic Fatty Liver in Lean Individuals: Clinicobiochemical Correlates of Histopathology in 157 Liver Biopsies from Healthy Liver Donors

BACKGROUND

Generally diagnosis of non-alcoholic fatty disease is made on imaging, however, mild steatosis is difficult to diagnose on imaging. Liver biopsy is the procedure of choice but is not carried out as it is an invasive procedure. We describe our experience of 157 liver biopsies in living liver donors with normal body mass index (BMI) <23 kg/M² (lean).

MATERIALS AND METHODS

The study was conducted at a tertiary care center in north India. Data of lean living donors who underwent a liver biopsy before donation were analyzed. Data are presented as percentage, mean, or median (25-75 interquartile range).

RESULTS

Of 718 donors who had a liver biopsy before donation, 157 (21.8%) donors were lean (BMI < 23 kg/M²). Seventy-eight percent of lean donors had no or only one metabolic risk factor. Fifty-three (33.7%) of lean donors had nonalcoholic fatty liver (NAFL) in liver biopsy. When donors with NAFL were compared to donors with normal histology, donors with NAFL had significantly higher aspartate transaminase (26.6 ± 7.5 versus 23.7 ± 5.4, p = 0.007), alanine transaminase (33.4 ± 11.7 versus 27.8 ± 10.7, p = 0.003), and gamma glutamyl transpeptidase [25 (16-40.5) versus 18 (14-23), p = 0.003]. Only triglycerides (TGs) were statistically different among metabolic factors in lean NAFL and normal histology groups, 97 (70-161) versus 86 (62.5-114.7), p = 0.043. A total of 30% donors in the lean NAFL group had TGs >150 mg/dl as compared with 12.5% in the normal histology group, p = 0.009. Other metabolic risk factors were not statistically different.

CONCLUSION

One third of lean donors had NAFL. Among all metabolic risk factors, only higher TGs levels showed a significant association with NAFL.

Vitamin D Level and Vitamin D Receptor Genetic Variation Were Involved in the Risk of Non-Alcoholic Fatty Liver Disease: A Case-Control Study

BACKGROUND

It has been demonstrated that vitamin D receptor (VDR), a key gene in the metabolism of vitamin D (VD), may affect the development of Non-alcoholic fatty liver disease (NAFLD) by regulating VD level and its biological effects.

OBJECTIVES

To investigate the effects of serum VD level, VDR variation, and a combination of VDR SNP and environmental behavior factor on the risk of NAFLD.

METHODS

A total of 3023 subjects from a community in Nanjing were enrolled, including 1120 NAFLD cases and 1903 controls. Serum 25(OH)D₃ levels were measured and eight single nucleotide polymorphisms (SNPs) in VDR gene were genotyped.

RESULTS

Logistic regression analyses indicated that VD sufficiency and VD insufficiency were significantly associated with a low risk of NAFLD (all P<0.05; all P_trend<0.05, in a locus-dosage manner). After adjusting for gender and age, VDR rs2228570-A and rs11168287-A alleles were all reduced the risk of NAFLD (all P_FDR=0.136, in dominant model; P_trend =0.039, combined effects in a locus-dosage manner). The protective effects of two favorable alleles were more evident among subjects ≤40 years, non-hypertension, non-hyperglycemia and non-low high density lipoprotein-cholesterol (all P<0.05). The area under the receiver operating curve of the combination of VDR SNP and exercise time for assessing NAFLD risk was slightly higher than that of only including exercise time or neither (all P<0.05).

CONCLUSION

High serum VD levels and VDR variants (rs2228570-A and rs11168287-A) might contribute to a low risk of NAFLD in Chinese Han population. The inclusion of VDR SNP and exercise time could improve the efficiency in assessment of NAFLD risk, which might provide a novel perspective for early screening and preventing NAFLD.

Non-Alcoholic Steatohepatitis: A Review of Its Mechanism, Models and Medical Treatments

Non-alcoholic steatohepatitis (NASH) develops from non-alcoholic fatty liver disease (NAFLD). Currently, around 25% of the population is estimated to have NAFLD, and 25% of NAFLD patients are estimated to have NASH. NASH is typically characterized by liver steatosis inflammation, and fibrosis driven by metabolic disruptions such as obesity, diabetes, and dyslipidemia. NASH patients with significant fibrosis have increased risk of developing cirrhosis and liver failure. Currently, NASH is the second leading cause for liver transplant in the United States. More importantly, the risk of developing hepatocellular carcinoma from NASH has also been highlighted in recent studies. Patients may have NAFLD for years before progressing into NASH. Although the pathogenesis of NASH is not completely understood, the current “multiple-hits” hypothesis suggests that in addition to fat accumulation, elevated oxidative and ER stress may also drive liver inflammation and fibrosis. The development of clinically relevant animal models and pharmacological treatments for NASH have been hampered by the limited understanding of the disease mechanism and a lack of sensitive, non-invasive diagnostic tools. Currently, most pre-clinical animal models are divided into three main groups which includes: genetic models, diet-induced, and toxin + diet-induced animal models. Although dietary models mimic the natural course of NASH in humans, the models often only induce mild liver injury. Many genetic and toxin + diet-induced models rapidly induce the development of metabolic disruption and serious liver injury, but not without their own shortcomings. This review provides an overview of the “multiple-hits” hypothesis and an evaluation of the currently existing animal models of NASH. This review also provides an update on the available interventions for managing NASH as well as pharmacological agents that are currently undergoing clinical trials for the treatment of NASH.

Nonalcoholic fatty liver disease in lean subjects: Prognosis, outcomes and management

Nonalcoholic fatty liver disease (NAFLD) accounts for most cases of chronic liver disease worldwide, with an estimated global prevalence of approximately 25% and ranges from simple steatosis to nonalcoholic steatohepatitis and cirrhosis. NAFLD is strongly connected to metabolic syndrome, and for many years, fatty liver was considered to be an exclusive feature of obese patients. However, recent studies have highlighted the presence of NAFLD in non-obese subjects, with or without increased visceral fat or even in lean subjects without increased waist circumference. "Lean NAFLD" is a relatively new concept and there is significant scientific interest in understanding the differences in pathophysiology, prognosis and management compared with NAFLD in overweight/obese patients. In the present editorial, we discuss the clinical and metabolic profiles and outcomes of lean NAFLD compared with both obese NAFLD and lean healthy individuals from Asian and Western countries. Moreover, we shed light to the challenging topic of management of NAFLD in lean subjects since there are no specific guidelines for this population. Finally, we discuss open questions and issues to be addressed in the future in order to categorize NAFLD patients into lean and non-lean cohorts.

Development and validation of screening scores of non-alcoholic fatty liver disease in middle-aged and elderly Chinese

AIM

Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease and also closely related to cardiometabolic disease. Its prevalence was estimated at over one-fourth in the general population in China. We aimed to develop effective score tools for detecting NAFLD.

METHODS

A total of 17,212 participants aged 45-70 years old were surveyed in Shanghai between 2013 and 2014, and 13,293 participants were included in this analysis. All participants were randomly classified into the exploratory group or the validation group. Candidate categorical variables were selected using a logistic regression model. The score points were generated according to the β-coefficients.

RESULTS

We developed the Shanghai Nicheng NAFLD Score I (SHNC NAFLD Score I), which included body mass index and waist circumference with an area under the receiver-operating characteristic curve (AUC) of 0.802 (95% CI 0.792-0.811) in the exploratory group and 0.802 (95% CI 0.793-0.812) in the validation group. We further developed the SHNC NAFLD Score II by adding fasting plasma glucose, triglyceride, and alanine aminotransferase/aspartate aminotransferase ratio to the SHNC NAFLD Score I, achieving an AUC of 0.852 (95% CI 0.843-0.861) in the exploratory group and 0.843 (95% CI 0.834-0.852) in the validation group. The two score tools also performed well in subjects with normal alanine aminotransferase (ALT) levels.

CONCLUSIONS

Based on anthropometric and clinical categorical variables, our two scores are effective tools for detecting NAFLD in both this southern Chinese population and their subpopulation with normal ALT levels.

The risk of cardiometabolic disorders in lean non-alcoholic fatty liver disease: A longitudinal study

Background

Recent studies suggest that non-alcoholic fatty liver disease (NAFLD) in lean (BMI<25 ​kg/m²) individuals presents a distinct phenotype. We sought to determine the cardiometabolic consequences of lean NAFLD in a population cohort of relatively young asymptomatic individuals who participated in a voluntary routine health promotion evaluation in Brazil.

Methods

We analyzed data in our population collected from 2004 to 2016. Medical and demographic history, anthropometric measures, and fasting blood samples were obtained. Participants had ultrasonography to assess for fatty liver. We defined NAFLD as fatty liver in individuals scoring below 8 on the alcohol use disorders identification test (AUDIT). We included data from 9137 individuals who had complete data at baseline and at follow-up.

Results

The prevalence of lean NAFLD in our cohort was 3.8%. Over the median follow-up period of 2.4 years (range 0.5–9.9 years), lean individuals had 74% (HR: 1.74 (1.39–2.18)) and 67% (1.67 (1.29–2.15)) greater risk of developing elevated BP and elevated glucose, and nearly 3 times the risk of atherogenic dyslipidemia (HR: 2.98 (2.10–4.24)) compared to lean individuals without NAFLD. Lean NAFLD individuals also had higher risk of developing elevated glucose (HR: 1.37 (1.07–1.75)) and atherogenic dyslipidemia (1.46 (1.05–2.01)) compared to non-lean individuals without NAFLD. However, there was no significant difference in the risk of elevated BP, elevated glucose or atherogenic dyslipidemia between lean NAFLD and non-lean individuals with NAFLD in fully adjusted models.

Conclusion

Lean NAFLD is not metabolically benign. Further cardiovascular risk stratification and appropriate preventive measures should be considered in lean individuals who present with NAFLD.

The transcontinental variability of nonalcoholic fatty liver disease

AIM

To compare the phenotype of lean versus overweight (OW) and obese (OB) subjects with non-alcoholic fatty liver disease (NAFLD) across multiple continents.

METHODS

A retrospective study of histologically defined subjects from a single center each in France (Fr), Brazil (Br), India (In) and United States (US) was performed.

RESULTS

A total of 70 lean [body mass index (BMI) < 25 kg/m2] subjects (Fr:Br:In:US: 16:19:22:13) with NAFLD were compared to 136 OW (BMI > 25 kg/m2, BMI < 29 kg/m2) (n = 28:33:52:23) and 224 OB subjects (BMI > 29 kg/m2) (n = 81:11:22:103). Lean French subjects had the lowest incidence of type 2 diabetes while those from Brazil (P < 0.01) had the highest. Lean subjects had similar low-density lipoprotein-cholesterol, but higher high-density lipoprotein-cholesterol compared to obese subjects in all regions. In both lean and obese subjects, there were both insulin-sensitive and insulin-resistant subjects. Lean French subjects were most insulin-sensitive while those from Brazil were mostly insulin-resistant. For each weight category, subjects from India were more insulin-sensitive than those from other regions. Disease activity increased from lean to overweight to obese in France but was similar across weight categories in other regions.

CONCLUSION

The phenotype of NAFLD in lean subjects varies by region. Some obese subjects with NAFLD are insulin-sensitive. We hypothesize that genetics and region-specific disease modifiers account for these differences.

Established and emerging factors affecting the progression of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease affecting approximately 25% of the global population. Although a majority of NAFLD patients will never experience liver-related symptoms it is estimated that 5-10% will develop cirrhosis-related complications with risk of death or need for liver transplantation. NAFLD is closely associated with cardiovascular disease and components of the metabolic syndrome. However, NAFLD is not uncommon in lean individuals and may in these subjects represent a different entity with separate pathophysiological mechanisms involved implying a higher risk for development of end-stage liver disease. There is considerable fluctuation in the histopathological course of NAFLD that may partly be attributed to lifestyle factors and dietary composition. Nutrients such as fructose, monounsaturated fatty acids, and trans-fatty acids may aggravate NAFLD. Presence of type 2 diabetes mellitus seems to be the most important clinical predictor of liver-related morbidity and mortality in NAFLD. Apart from severity of the metabolic syndrome, genetic polymorphisms and environmental factors, such as moderate alcohol consumption, may explain the variation in histopathological and clinical outcome among NAFLD patients.

Role of intensive dietary and lifestyle interventions in the treatment of lean nonalcoholic fatty liver disease patients

BACKGROUND/AIM

Although weight loss is recommended for the treatment of nonalcoholic fatty liver disease (NAFLD) in overweight and obese individuals, this treatment modality remains questionable in lean individuals. In this study, we investigated the effects of medical nutrition therapy (MNT) and intensive lifestyle interventions (ILIs) for NAFLD in lean versus obese patients.

METHODS

In total, 35 patients (14 lean and 21 obese) were included in the study. All patients underwent transient elastography examinations, and controlled attenuation parameter (CAP) of >238 dB/m was indicative of hepatic steatosis. After 8 weeks of dietitian follow-up with MNT and ILI, the patients were compared with the baseline.

RESULTS

Significant weight loss was recorded in both lean (5.4%) and obese patients (5.7%) with NAFLD. The mean BMI decreased from 23.9 (20.5-24.8) to 22.4 (19.5-24.2) kg/m (P = 0.001) in lean patients and from 34.0 (30.0-42.0) to 31.6 (26.9-42.5) kg/m (P < 0.001) in obese patients. The alanine aminotransferase level significantly decreased from 56 (15-163) to 28 (13-98) U/L (P = 0.010) in lean patients and from 27 (13-81) to 22 (13-46) U/L (P = 0.018) in obese patients. The median CAP decreased from 299 (246-360) to 236 (169-318) dB/m (P = 0.002) in lean patients and from 325 (258-400) to 253 (202-383) dB/m (P < 0.001) in obese patients. Moreover, remission of hepatic steatosis was detected in eight lean patients (57.1%) and eight obese patients (38.1%).

CONCLUSION

These results indicate that 5% body weight loss in effective in both obese and lean patients resulting in a similar NAFLD remission.

Rescue of Hepatic Phospholipid Remodeling Defectin iPLA2β-Null Mice Attenuates Obese but Not Non-Obese Fatty Liver

Polymorphisms of group VIA calcium-independent phospholipase A2 (iPLA₂β or PLA2G6) are positively associated with adiposity, blood lipids, and Type-2 diabetes. The ubiquitously expressed iPLA₂β catalyzes the hydrolysis of phospholipids (PLs) to generate a fatty acid and a lysoPL. We studied the role of iPLA₂β on PL metabolism in non-alcoholic fatty liver disease (NAFLD). By using global deletion iPLA₂β-null mice, we investigated three NAFLD mouse models; genetic Ob/Ob and long-term high-fat-diet (HFD) feeding (representing obese NAFLD) as well as feeding with methionine- and choline-deficient (MCD) diet (representing non-obese NAFLD). A decrease of hepatic PLs containing monounsaturated- and polyunsaturated fatty acids and a decrease of the ratio between PLs and cholesterol esters were observed in all three NAFLD models. iPLA₂β deficiency rescued these decreases in obese, but not in non-obese, NAFLD models. iPLA₂β deficiency elicited protection against fatty liver and obesity in the order of Ob/Ob › HFD » MCD. Liver inflammation was not protected in HFD NAFLD, and that liver fibrosis was even exaggerated in non-obese MCD model. Thus, the rescue of hepatic PL remodeling defect observed in iPLA₂β-null mice was critical for the protection against NAFLD and obesity. However, iPLA₂β deletion in specific cell types such as macrophages may render liver inflammation and fibrosis, independent of steatosis protection.

Role of Fatty Liver Index and Metabolic Factors in the Prediction of Nonalcoholic Fatty Liver Disease in a Lean Population Receiving Health Checkup

OBJECTIVES

Some metabolic factors and noninvasive markers, including fatty liver index (FLI), are used to predict nonalcoholic fatty liver disease (NAFLD) in obese patients. Despite the increasing prevalence of NAFLD in lean patients (lean-NAFLD), the risk factors and predictors are not well determined in this population. We investigated factors associated with lean-NAFLD and validated their predictive ability.

METHODS

From 9,293 examinees who underwent routine health checkups, we enrolled 4,000, aged ≥20 years, with a body mass index <24 kg/m in our lean-NAFLD study population. NAFLD diagnoses were made according to the patients' histories, laboratory values, and sonographic criteria. Clinical variables, serum sugar, lipid, and liver profiles were evaluated using multiple logistic regression analysis. The predictive ability and optimal cutoff values for NAFLD were determined according to the area under the receiver operating characteristic curve.

RESULTS

Overall, 18.5% (n = 740) of the lean population had NAFLD. Male sex, body mass index, body fat mass, fasting plasma glucose, uric acid, alanine aminotransferase, triglyceride, and FLI values were associated with NAFLD. FLI had the best discriminative ability to predict lean-NAFLD compared to the other biochemical markers. We further used the Youden index test and found an optimum cut-off value for FLI of 15 with the highest discriminant ability than other values.

DISCUSSION

The prevalence of lean-NAFLD was not low. FLI was superior to other predictors including sex, liver function, and other metabolic factors, in the prediction of lean-NAFLD. FLI may be considered an easy to use, noninvasive marker to screen for lean-NAFLD.

Characterization of biopsy proven non-alcoholic fatty liver disease in healthy non-obese and lean population of living liver donors: The impact of uric acid

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is frequently seen among non-obese overweight individuals and lean subjects (those with normal body mass index). This study aimed to investigate prevalence and risk factors of biopsy proven NAFLD in a cluster of healthy non-obese and lean individuals.

METHODS AND MATERIALS

In a retrospective study, adult (>18 years) apparently healthy individuals who had donated liver to pediatric patients between July 2012 and October 2018 were included. Non-obese and lean individuals were defined as BMI<30kg/m2 and BMI<25kg/m2, respectively.

RESULTS

Totally 310 patients were included. Seventy-six individuals (24.5%) had NAFL and 30 patients (9.67%) had non-alcoholic steatohepatitis (NASH) among non-obese population. In multivariate regression analysis, only higher BMI was marginally associated with NASH in non-obese compared to those without NASH (Odds ratio: 2.52, 95% CI: 0.097-6.54; P=0.05). Totally, 246 individuals were lean. 55 individuals (22.3%) had NAFL and 20 individuals (8.2%) had NASH in their liver biopsies. In univariate analysis, serum triglyceride, cholesterol, LDL, ALT, alkaline phosphatase and uric acid were associated with NAFL among lean individuals (P<0.05). In regression analysis, serum uric acid was associated with NAFL (Odds ratio: 1.70, 95% CI: 1.18-2.45; P=0.004) and NASH in lean individuals (Odds ratio: 1.98, 95% CI: 1.27-3.10; P=0.003).

CONCLUSION

NAFLD/NASH is prevalent even in a healthy lean population when evaluated by liver biopsy. Higher BMI and serum uric acid were two major risks of NAFLD/NASH in non-obese and lean individuals.

Circulating histone signature of human lean metabolic-associated fatty liver disease (MAFLD)

BACKGROUND

Although metabolic associate fatty liver disease (MAFLD) is associated with obesity, it can also occur in lean patients. MAFLD is more aggressive in lean patients compared to obese patients, with a higher risk of mortality. Specific biomarkers to diagnose differentially lean or overweight MAFLD are missing. Histones and nucleosomes are released in the bloodstream upon cell death. Here, we propose a new, fast, imaging and epigenetics based approach to investigate the severity of steatosis in lean MAFLD patients.

RESULTS

A total of 53 non-obese patients with histologically confirmed diagnosis of MAFLD were recruited. Twenty patients displayed steatosis grade 1 (0-33%), 24 patients with steatosis grade 2 (34-66%) and 9 patients with steatosis grade 3 (67-100%). The levels of circulating nucleosomes were assayed using enzyme-linked immunosorbent assay, while individual histones or histone dimers were assayed in serum samples by means of a new advanced flow cytometry ImageStream(X)-adapted method. Circulating nucleosome levels associated poorly with MAFLD in the absence of obesity. We implemented successfully a multi-channel flow methodology on ImageStream(X), to image single histone staining (H2A, H2B, H3, H4, macroH2A1.1 and macroH2A1.2). We report here a significant depletion of the levels of histone variants macroH2A1.1 and macroH2A1.2 in the serum of lean MAFLD patients, either individually or in complex with H2B.

CONCLUSIONS

In summary, we identified a new circulating histone signature able to discriminate the severity of steatosis in individuals with lean MAFLD, using a rapid and non-invasive ImageStream(X)-based imaging technology.

Protective effect of fenofibrate against high-fat-high-fructose diet induced non-obese NAFLD in rats

The present study evaluated the protective effects of fenofibrate on liver function, oxidant-antioxidant balance, and insulin resistance (IR) in rats fed high-fat-high-fructose diet (HFFD). Twenty-four male Sprague-Dawley rats (110-130 gm) were allocated into four equal groups (n = 6). Rats in group I were fed a normal diet for 4 weeks. Rats in group II were fed a normal diet with fenofibrate at 50 mg/kg/day orally for four weeks. Rats in group III were fed a normal diet mixed with 25% palm oil and given 60% fructose solution orally for 4 weeks. Rats in group IV were fed a normal diet mixed with 25% palm oil, 60% oral fructose solution, and fenofibrate at 50 mg/kg/day orally for four weeks. After experimental induction, serum and liver tissue samples were collected to determine lipid profiles, glycemic status, antioxidant status, oxidative and stress markers, and histopathology of liver tissues. The results of the present study revealed that fenofibrate prevents the occurrence of fatty liver, enhancing glycemic status, decreasing oxidative stress, and improving antioxidant status. It can be concluded that fenofibrate has a lipotropic and antidiabetic role.

The Morbidity and Comorbidity of Nonalcoholic Fatty Liver Disease and Different Glucose Intolerance Strata in a Community-Based Chinese Population

Objective: To investigate the morbidity and comorbidity of nonalcoholic fatty liver disease (NAFLD) and different glucose intolerance strata in a community-based population and to explore the association between glucose tolerance levels and NAFLD. Methods: A community-based cohort established for Pinggu Metabolic Disease Study in a suburb of Beijing, China, was established from September 2013 to July 2014 using a random sampling method. Participants were eligible if they were born in Pinggu and had been living there for at least 5 years within the age range of 26-76 years. A 75 grams oral glucose tolerance test was used to determine the strata of glucose tolerance. Unenhanced abdominal computed tomography scan was performed to identify NAFLD. Results: A total of 3122 subjects were included in this analysis. The prevalence of NAFLD was 22.68% (27.58% vs. 19.97% among men and women). The prevalence of type 2 diabetes (T2D) was 18.03% (20.83% vs. 16.22% among men and women). Up to 7.21% of residents had both T2D and NAFLD. 39.96% of diabetic patients and 28.77% of prediabetic patients combined with NAFLD. Compared with adults with normal glucose tolerance, the incidence of NAFLD in T2D patients was more than three times higher after adjusting for sex, age, body mass index (BMI), sedentary time, and dietary habit [odds ratio (OR) = 3.58, confidence interval (95% CI) 2.80-4.58, P < 0.001]. NAFLD was also more common in individuals with prediabetes, especially patients with impaired glucose tolerance (IGT) (OR = 2.27, 1.75-2.95) or impaired fasting glucose+IGT (OR = 2.78, 1.92-4.03). Conclusions: The morbidity and comorbidity of NAFLD and glucose intolerance are high in the Pinggu population in northern China, highlighting the importance of early prevention and treatment of these two diseases at the same time.

Non-alcoholic fatty liver disease (NAFLD) among underweight adults

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), closely linked to obesity, has also been evident in lean and underweight adults. But data pertaining to NAFLD in underweight adults in Bangladesh is very limited. Therefore, we sought to estimate the prevalence and identify the factors associated with NAFLD in underweight adults in Bangladesh.

METHODS

Underweight adults (BMI <18.5 kg/m2) who underwent abdominal imaging from December 2015 to January 2017 were included in this analysis. Multivariable logistic regression was performed to identify the factors associated with NAFLD in underweight adults.

RESULTS

Total 286 (female = 117) participants with a mean age of 28.4 (±13.0) years were included in this analysis. The prevalence of NAFLD in underweight adults was 5.2% (95% CI: 2.6, 7.8). The prevalence was higher in adults ≥30 years (9.2 vs. 3.5 p-value = 0.048), married (9.0 vs. 1.4, p-value = 0.004), sedentary workers (8.7 vs. 1.5, p-value = 0.006, and diabetic individuals (60.0 vs. 5.0, p-value<0.001) compared to their counterparts. Multivariable logistic regression model demonstrated that rural residents had higher odds (aOR: 3.93, 95% CI: 1.07, 14.49, p-value = 0.048) of having NAFLD than urban inhabitants. The odds of NAFLD was 5 times higher (aOR: 5.60, 95% CI: 1.04, 30.29, p-value = 0.046) in patients with positive family history of metabolic traits. Being non-diabetic was protective against NAFLD (aOR: 0.06, 95% CI: 0.01, 0.45, p-value = 0.005) in this selected population.

CONCLUSION

The study results delineate that underweight adults living in rural areas, with a positive family history of metabolic traits and being diabetic are more likely to develop NAFLD in Bangladesh.

Global prevalence, incidence, and outcomes of non-obese or lean non-alcoholic fatty liver disease: a systematic review and meta-analysis

BACKGROUND

Although non-alcoholic fatty liver disease (NAFLD) is commonly associated with obesity, it is increasingly being identified in non-obese individuals. We aimed to characterise the prevalence, incidence, and long-term outcomes of non-obese or lean NAFLD at a global level.

METHODS

For this systematic review and meta-analysis, we searched PubMed, Embase, Scopus, and the Cochrane Library from inception to May 1, 2019, for relevant original research articles without any language restrictions. The literature search and data extraction were done independently by two investigators. Primary outcomes were the prevalence of non-obese or lean people within the NAFLD group and the prevalence of non-obese or lean NAFLD in the general, non-obese, and lean populations; the incidence of NAFLD among non-obese and lean populations; and long-term outcomes of non-obese people with NAFLD. We also aimed to characterise the demographic, clinical, and histological characteristics of individuals with non-obese NAFLD.

FINDINGS

We identified 93 studies (n=10 576 383) from 24 countries or areas: 84 studies (n=10 530 308) were used for the prevalence analysis, five (n=9121) were used for the incidence analysis, and eight (n=36 954) were used for the outcomes analysis. Within the NAFLD population, 19·2% (95% CI 15·9-23·0) of people were lean and 40·8% (36·6-45·1) were non-obese. The prevalence of non-obese NAFLD in the general population varied from 25% or lower in some countries (eg, Malaysia and Pakistan) to higher than 50% in others (eg, Austria, Mexico, and Sweden). In the general population (comprising individuals with and without NAFLD), 12·1% (95% CI 9·3-15·6) of people had non-obese NAFLD and 5·1% (3·7-7·0) had lean NAFLD. The incidence of NAFLD in the non-obese population (without NAFLD at baseline) was 24·6 (95% CI 13·4-39·2) per 1000 person-years. Among people with non-obese or lean NALFD, 39·0% (95% CI 24·1-56·3) had non-alcoholic steatohepatitis, 29·2% (21·9-37·9) had significant fibrosis (stage ≥2), and 3·2% (1·5-5·7) had cirrhosis. Among the non-obese or lean NAFLD population, the incidence of all-cause mortality was 12·1 (95% CI 0·5-38·8) per 1000 person-years, that for liver-related mortality was 4·1 (1·9-7·1) per 1000 person-years, cardiovascular-related mortality was 4·0 (0·1-14·9) per 1000 person-years, new-onset diabetes was 12·6 (8·0-18·3) per 1000 person-years, new-onset cardiovascular disease was 18·7 (9·2-31·2) per 1000 person-years, and new-onset hypertension was 56·1 (38·5-77·0) per 1000 person-years. Most analyses were characterised by high heterogeneity.

INTERPRETATION

Overall, around 40% of the global NAFLD population was classified as non-obese and almost a fifth was lean. Both non-obese and lean groups had substantial long-term liver and non-liver comorbidities. These findings suggest that obesity should not be the sole criterion for NAFLD screening. Moreover, clinical trials of treatments for NAFLD should include participants across all body-mass index ranges.

FUNDING

None.

Prevalence and Profile of Nonalcoholic Fatty Liver Disease in Lean Adults: Systematic Review and Meta-Analysis

Data on prevalence and profile of nonalcoholic fatty liver disease (NAFLD) among individuals who are lean (normal body mass index) is unclear. Published data from studies comparing lean with obese NAFLD or with healthy subjects on prevalence, comorbidities, liver chemistry and histology, and metabolic/inflammatory markers were analyzed. Data were reported as odds ratio and 95% confidence interval for categorical variables and difference of means for continuous variables. Analysis of 53 studies on 65,029 subjects with NAFLD (38,084 lean) and 249,544 healthy subjects showed a prevalence of lean NAFLD at 11.2% in the general population. Among individuals with NAFLD, the prevalence of lean NAFLD was 25.3%. Lean NAFLD versus healthy subjects had higher odds for abnormalities on metabolic profile, including metabolic syndrome and its components, renal and liver function, and patatin-like phospholipase domain-containing protein 3 (PNPLA3) G allele; and inflammatory profile, including uric acid and C-reactive protein. The abnormalities were less severe among lean versus obese NAFLD on metabolic syndrome with its components, renal and liver chemistry, liver stiffness measurement, PNPLA3 and transmembrane 6 superfamily member 2 polymorphisms, and uric acid levels as markers of inflammation. Lean NAFLD had less severe histologic findings, including hepatocyte ballooning, lobular inflammation, NAFLD activity score, and fibrosis stage. Limited data also showed worse outcomes between obese versus lean NAFLD. Conclusion: Lean NAFLD is a distinct entity with metabolic, biochemical, and inflammatory abnormalities compared to healthy subjects and a more favorable profile, including liver histology of steatohepatitis and fibrosis stage, compared to obese NAFLD. We suggest that prospective multicenter studies examine long-term hepatic and extrahepatic outcomes in individuals with lean NAFLD.

Decrease in waist-to-hip ratio reduced the development of chronic kidney disease in non-obese non-alcoholic fatty liver disease

To date, there are few studies that have evaluated the prognostic impact of changes in abdominal obesity or weight on long-term adverse kidney outcomes in non-alcoholic fatty liver disease (NAFLD). We investigated the effect of changes in waist-to-hip ratio (WHR) and body weight (BW) on chronic kidney disease (CKD) development, especially in non-obese NAFLD patients. We included 6,137 participants from a community-based prospective cohort with 12-year follow-up in Korea. NAFLD patients were categorized according to time-averaged percent changes in WHR and BW (≤−5%, >−5% to <5%, and ≥5%). Compared to non-obese controls, non-obese NAFLD was significantly associated with an increased risk of incident CKD (hazard ratio [HR] = 1.238, 95% confidence interval [CI] = 1.006–1.524). In 1,563 NAFLD patients, compared to patients with minimal changes in WHR (>−5% to <5%), patients with a decreased WHR (≤−5%) had a significantly attenuated risk of CKD development (HR = 0.300; 95% CI = 0.194–0.464). Furthermore, risk reduction from decreased WHR for developing CKD remained significant in non-obese NAFLD patients (HR = 0.290; 95% CI = 0.114–0.736). In conclusion, a decrease in WHR of more than 5% significantly reduced the risk of CKD development in NAFLD patients, even in those who were non-obese. Thus, serial monitoring of WHR may be prioritized in the management of NAFLD.

Epidemiological Features of NAFLD From 1999 to 2018 in China

With dramatic changes in lifestyles over the last 20 years, nonalcoholic fatty liver disease (NAFLD) has become the most prevalent liver disorder in China but has not received sufficient attention. NAFLD-related advanced liver disease and its mortality along with its overall disease burden are expected to increase substantially. There is thus an imperative need to clarify the epidemiological features of NAFLD to guide a holistic approach to management. We summarize eight epidemiological features of NAFLD in China over the past two decades using systematic review and meta-analysis methodology. Our data reveal a rapid growth in the NAFLD population, especially among younger individuals. Importantly, there is a strong ethnic difference in body mass index (BMI) and genetic risk of NAFLD compared with the US population. The etiology of advanced liver disease and its complications (e.g., hepatocellular carcinoma) has been altered because of a Westernized lifestyle and the implementation of effective vaccination strategies against viral hepatitis. Regional epidemiological patterns of NAFLD indicate that economics, environment, and lifestyle are critical factors in disease progression. The analysis also indicates that a large number of patients remain undiagnosed and untreated because of the inadequacy of diagnostic tools and the absence of effective pharmacologic therapies. Given the burden of NAFLD, future policy and research efforts need to address knowledge gaps to mitigate the risk burden.