Paediatric fatty liver disease (PeFLD): All is not NAFLD - Pathophysiological insights and approach to management

Mitochondrial dysfunction in drug-induced hepatic steatosis: Recent findings and current concept

Mitochondrial activity is necessary for the maintenance of many liver functions. In particular, mitochondrial fatty acid oxidation (FAO) is required for energy production and lipid homeostasis. This key metabolic pathway is finely tuned by the mitochondrial respiratory chain (MRC) activity and different transcription factors such as peroxisome proliferator-activated receptor α (PPARα). Many drugs have been shown to cause mitochondrial dysfunction, which can lead to acute and chronic liver lesions. While severe inhibition of mitochondrial FAO would eventually cause microvesicular steatosis, hypoglycemia, and liver failure, moderate impairment of this metabolic pathway can induce macrovacuolar steatosis, which can progress in the long term to steatohepatitis and cirrhosis. Drugs can impair mitochondrial FAO through several mechanisms including direct inhibition of FAO enzymes, sequestration of coenzyme A and l-carnitine, impairment of the activity of one or several MRC complexes and reduced PPARα expression. In drug-induced macrovacuolar steatosis, non-mitochondrial mechanisms can also be involved in lipid accumulation including increased de novo lipogenesis and reduced very-low-density lipoprotein secretion. Nonetheless, mitochondrial dysfunction and subsequent oxidative stress appear to be key events in the progression of steatosis to steatohepatitis. Patients suffering from metabolic dysfunction-associated steatotic liver disease (MASLD) and treated with mitochondriotoxic drugs should be closely monitored to reduce the risk of acute liver injury or a faster transition of steatosis to steatohepatitis. Therapies based on the mitochondrial cofactor l-carnitine, the antioxidant N-acetylcysteine, or thyromimetics might be useful to prevent or treat drug-induced mitochondrial dysfunction, steatosis, and steatohepatitis.

Exploring Biomarkers in Nonalcoholic Fatty Liver Disease Among Individuals With Type 2 Diabetes Mellitus

Integrating biomarkers into a comprehensive strategy is crucial for precise patient management, especially considering the significant healthcare costs associated with diseases. Current studies emphasize the urgent need for a paradigm shift in conceptualizing nonalcoholic fatty liver disease (NAFLD), now renamed metabolic dysfunction-associated steatotic liver disease (MASLD). Biomarkers are emerging as indispensable tools for accurate diagnosis, risk stratification, and monitoring disease progression. This review classifies biomarkers into conventional and novel categories, such as lipids, insulin resistance, hepatic function, and cutting-edge imaging/omics, and evaluates their potential to transform the approach to MASLD among individuals with type 2 diabetes mellitus (T2D). It focuses on the critical role of biomarkers in early MASLD detection, enhancing predictive accuracy, and discerning responses to interventions (pharmacological or lifestyle modifications). Amid this discussion, the complexities of the relationship between T2D and MASLD are explored, considering factors like age, gender, genetics, ethnicity, and socioeconomic background. Biomarkers enhance the effectiveness of interventions and support global initiatives to reduce the burden of MASLD, thereby improving public health outcomes. This review recognizes the promising potential of biomarkers for diagnostic precision while candidly addressing the challenges in implementing these advancements in clinical practice. The transformative role of biomarkers emerges as a central theme, promising to reshape our understanding of disease trajectories, prognosis, and the customization of personalized therapeutic strategies for improved patient outcomes. From a future perspective, identifying early-stage biomarkers, understanding environmental impact through exposomes, and applying a multiomics approach may reveal additional insight into MASLD development.

Practice Recommendations for Metabolic Dysfunction-Associated Steatotic Liver Disease by the Indian Society of Pediatric Gastroenterology, Hepatology and Nutrition (ISPGHAN)

JUSTIFICATION

There has been an alarming increase in metabolic dysfunction-associated steatotic liver disease (MASLD) and it is now the most common chronic liver disease worldwide, in both adult and pediatric populations. The lack of regional guidelines has hampered the formulation of national policies for prevention and management of MASLD in children. Therefore, we formulated recommendations for steatotic liver disease in children.

OBJECTIVES

To review the existing literature on the burden and epidemiology of pediatric MASLD and formulate recommendations for diagnostic evaluation, prevention, and management strategies.

PROCESS

The Indian Society of Pediatric Gastroenterology, Hepatology, and Nutrition invited national and international stakeholders to participate in a consensus meeting held on April 20, 2024, in Mumbai, Maharashtra, India. Various aspects of pediatric steatotic liver disease were deliberated upon and a consensus document and recommendations were formulated after several rounds of discussion.

RECOMMENDATIONS

Metabolic dysfunction-associated steatotic liver disease (MASLD) should be used as the preferred term in place of non-alcoholic fatty liver disease (NAFLD). There is a high prevalence of steatotic liver disease (SLD) among Indian children and adolescents, especially those who are overweight or obese. This condition may be progressive in childhood and associated with increased morbidity and mortality in adulthood. Various lifestyle, dietary, and genetic factors may predispose individuals to MASLD, including an increased intake of calorie-dense processed foods, sweetened sugar beverages, excessive screen time, higher sedentary time and lack of moderate to vigorous physical activity. MASLD is usually asymptomatic or presents with mild, non-specific symptoms and therefore, a high degree of suspicion is required for early diagnosis. MASLD is usually associated with cardiometabolic factors (hypertension, insulin resistance/diabetes mellitus, and/or dyslipidemia) and secondary causes should be excluded in all cases, particularly in the presence of red flag signs. Screening for MASLD should be considered in all obese children (body mass index or BMI ≥95th percentile) and in all overweight children (BMI ≥ 85th and <95thpercentile) with additional risk factors, such as prediabetes/diabetes, dyslipidemia, positive family history of metabolic syndrome, obstructive sleep apnea, and hypopituitarism. Abdominal ultrasound in combination with alanine aminotransferase (ALT) levels should be used as a screening test for MASLD in Indian children as per the proposed algorithm. Diet (any hypocaloric diet) and exercise (aerobic, resistance, or a combination of both; moderate to high intensity; regular in frequency) remain the cornerstones of pediatric MASLD management. Pharmacotherapy and/or endoscopic/surgical techniques for obesity should be considered as adjuncts and should be considered only after a failed adequate trial of lifestyle modifications.

Pediatric metabolic (dysfunction)-associated fatty liver disease: current insights and future perspectives

The historical use of the term non-alcoholic fatty liver disease (NAFLD) in obese/overweight children has been controversial as to the appropriateness of this terminology in children, and lately, in adults too. Newer game-changer terminology, metabolic (dysfunction)-associated fatty liver disease (MAFLD), for this condition signifies a positive step forward that addresses the limitations of the previous definition for both adults and children. The prevalence of MAFLD has surged in tandem with the global rise in obesity rates, establishing itself as a predominant cause of chronic liver disease in both adult and pediatric populations. The adoption of the recently proposed nomenclature reflects a more encompassing comprehension of the disease and its etiology compared to its predecessor, NAFLD. Notably, the revised terminology facilitates the recognition of MAFLD as an autonomous condition while acknowledging the potential coexistence of other systemic fatty liver disorders. Particularly in children, this includes various paediatric-onset genetic and inherited metabolic disorders, necessitating thorough exclusion, especially in cases where weight loss interventions yield no improvement or in the absence of obesity. MAFLD presents as a multifaceted disorder; evidence suggests its origins lie in a complex interplay of nutritional, genetic, hormonal, and environmental factors. Despite advancements, current non-invasive diagnostic biomarkers exhibit limitations in accuracy, often necessitating imaging and histological evaluations for definitive diagnosis. While dietary and lifestyle modifications stand as cornerstone measures for MAFLD prevention and management, ongoing evaluation of therapeutic agents continues. This article provides an overview of the latest developments and emerging therapies in the realm of paediatric MAFLD.

Analysis of risk factors for fatty liver disease in children with Wilson's disease

BACKGROUND AND AIMS

Many children with Wilson's disease are complicated with dyslipidemia. The aim of this study was to investigate the risk factors for the development of fatty liver disease (FLD) in children with Wilson's disease.

METHODS

We evaluated sex, age, weight, the disease course, treatment course, clinical classification, alanine transaminase (ALT), aspartate transaminase, γ-glutamyl transpeptidase, total biliary acid, triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, homocysteine, uric acid, fibrinogen (FBG), creatinine, procollagen III N-terminal propeptide, laminin, hyaluronic acid, type IV collagen, and performed receiver operating characteristic curve analysis to investigate the forecast value of individual biochemical predictors and combined predictive indicators to evaluate FLD in Wilson's disease.

RESULTS

The multivariate logistic regression analysis revealed that ALT [odds ratio (OR), 1.011; 95% confidence interval (CI), 1.004-1.02; P  = 0.006], uric acid (OR, 1.01; 95% CI, 1.002-1.018; P  = 0.017), FBG (OR, 3.668; 95% CI, 1.145-13.71; P  = 0.037), creatinine (OR, 0.872; 95% CI, 0.81-0.925; P  < 0.001), and laminin (OR, 1.01; 95% CI, 1.002-1.018; P  = 0.017) acted as independent risk factors in Wilson's disease complicated with FLD. The receiver operating characteristic curves for combined predictive indicators demonstrated an area under the curve values of 0.872, which was found to be a significant predictors for FLD in Wilson's disease.

CONCLUSIONS

We screened out the most important risk factors, namely ALT, uric acid, creatinine, FBG, and laminin for Wilson's disease complicated with FLD. The joint prediction achieved is crucial for identifying children with Wilson's disease complicated with FLD.

Drug-induced impairment of mitochondrial fatty acid oxidation and steatosis: assessment of causal relationship with 45 pharmaceuticals

Drug-induced liver injury (DILI) represents a major issue for pharmaceutical companies, being a potential cause of black-box warnings on marketed pharmaceuticals, or drug withdrawal from the market. Lipid accumulation in the liver also referred to as steatosis, may be secondary to impaired mitochondrial fatty acid oxidation (mtFAO). However, an overall causal relationship between drug-induced mtFAO inhibition and the occurrence of steatosis in patients has not yet been established with a high number of pharmaceuticals. Hence, 32 steatogenic and 13 nonsteatogenic drugs were tested for their ability to inhibit mtFAO in isolated mouse liver mitochondria. To this end, mitochondrial respiration was measured with palmitoyl-l-carnitine, palmitoyl-CoA + l-carnitine, or octanoyl- l-carnitine. This mtFAO tri-parametric assay was able to predict the occurrence of steatosis in patients with a sensitivity and positive predictive value above 88%. To get further information regarding the mechanism of drug-induced mtFAO impairment, mitochondrial respiration was also measured with malate/glutamate or succinate. Drugs such as diclofenac, methotrexate, and troglitazone could inhibit mtFAO secondary to an impairment of the mitochondrial respiratory chain, whereas dexamethasone, olanzapine, and zidovudine appeared to impair mtFAO directly. Mitochondrial swelling, transmembrane potential, and production of reactive oxygen species were also assessed for all compounds. Only the steatogenic drugs amiodarone, ketoconazole, lovastatin, and toremifene altered all these 3 mitochondrial parameters. In conclusion, our tri-parametric mtFAO assay could be useful in predicting the occurrence of steatosis in patients. The combination of this assay with other mitochondrial parameters could also help to better understand the mechanism of drug-induced mtFAO inhibition.

European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN), European Association for the Study of the Liver (EASL), North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN), Latin‐American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (LASPGHAN), Asian Pan‐Pacific Society for Pediatric Gastroenterology, Hepatology and Nutrition (APPSPGHAN), Pan Arab Society for Pediatric Gastroenterology and Nutrition (PASPGHAN), Commonwealth Association of Paediatric Gastroenterology & Nutrition (CAPGAN), Federation of International Societies of Pediatric Hepatology, Gastroenterology and Nutrition (FISPGHAN). Paediatric steatotic liver disease has unique characteristics: A multisociety statement endorsing the new nomenclature

Nonalcoholic fatty liver disease (NAFLD) has been a commonly used term and diagnosis in paediatric hepatology, gastroenterology, and endocrinology clinics for over 30 years. A multisociety Delphi process has determined a new name "Steatotic Liver Disease" (SLD) as the overarching term for disorders associated with hepatic lipid accumulation. Our Societies give our support to steatotic liver disease as the best overarching term for use in our communities. Metabolic dysfunction-associated steatotic liver disease (MASLD) overcomes many of the shortcomings of the name NAFLD. Here, we highlight several points of the new nomenclature that are of particular importance for our community and their consequences for implementation including: diagnostic criteria, considering alternate diagnoses, practical implementation, research, advocacy, and education for paediatricians. As with all nomenclature changes, it will take a concerted effort from our paediatric societies to help integrate the optimal use of this into practice.

Carnitine-acylcarnitine translocase deficiency: a case report with autopsy

Fatty acid oxidation defects are a heterogeneous group of disorders related to the mitochondrial fatty acid oxidation pathway. Carnitine acylcarnitine translocase (CACT) is an enzyme responsible for the unidirectional transport of acylcarnitine across the inner mitochondrial membrane. This enzyme plays a crucial role in the oxidation of fatty acids. The autopsy pathology of the CACT deficiency is described in only a few cases. We describe the autopsy pathology of a child with CACT deficiency dominantly in the form of microvesicular steatosis of the hepatocytes, renal proximal tubular epithelia, cardiac myocytes, and rhabdomyocytes. The diagnosis was further confirmed on whole exome sequencing with compound heterozygous variants in the exon 1 (c.82G>T, p.Gly28Cys; likely pathogenic) and exon 5 (c.535G>A, p.Asp179Asn; uncertain significance) of the SLC25A20 gene. This case elucidates the histopathology of the liver and the detailed autopsy of a case of CACT deficiency from India.

Gender differences in non-alcoholic fatty liver disease in obese children and adolescents: a large cross-sectional study

OBJECTIVE

Previous studies have reported sex differences in non-alcoholic fatty liver disease (NAFLD) among adults; however, little is known about its occurrence in children and adolescents. This study aims to examine the prevalence of NAFLD among them and investigate the relationship between sex hormones and NAFLD.

METHOD

This study included 2999 obese Chinese children aged 2-18 years. We examined the prevalence of NAFLD by sex, age, and Tanner stage. The regression model and principal component analysis were used to analyze the relationship between sex hormones and NAFLD.

RESULTS

The prevalence of NAFLD increased with age in both sexes, and the gender difference appeared before puberty. The prevalence in boys tended to stabilize at the age of 11 years, whereas girls reached their peak temporarily. NAFLD prevalence was positively associated with estradiol in boys (p = 0.011), but the opposite trend was observed in girls (p = 0.031). Testosterone levels decreased with the increase of NAFLD prevalence in boys (p < 0.001). Luteinizing hormone and prolactin were inversely associated with NAFLD prevalence in boys and girls, respectively. Results from the principal component analysis showed that sex hormone levels and fat distribution were important risk factors for the prevalence of NAFLD in obese children (p < 0.001).

CONCLUSION

The significant difference in NAFLD prevalence between genders in obese children begins in early childhood. This distinction emerges long before puberty onset and tends to stabilize during late adolescence. Sex hormones are associated with NAFLD prevalence and are influenced by the Tanner stages and fat distribution.

Research progress on rodent models and its mechanisms of liver injury

The liver is the most important organ for biological transformation in the body and is crucial for maintaining the body's vital activities. Liver injury is a serious pathological condition that is commonly found in many liver diseases. It has a high incidence rate, is difficult to cure, and is prone to recurrence. Liver injury can cause serious harm to the body, ranging from mild to severe fatty liver disease. If the condition continues to worsen, it can lead to liver fibrosis and cirrhosis, ultimately resulting in liver failure or liver cancer, which can seriously endanger human life and health. Therefore, establishing an rodent model that mimics the pathogenesis and severity of clinical liver injury is of great significance for better understanding the pathogenesis of liver injury patients and developing more effective clinical treatment methods. The author of this article summarizes common chemical liver injury models, immune liver injury models, alcoholic liver injury models, drug-induced liver injury models, and systematically elaborates on the modeling methods, mechanisms of action, pathways of action, and advantages or disadvantages of each type of model. The aim of this study is to establish reliable rodent models for researchers to use in exploring anti-liver injury and hepatoprotective drugs. By creating more accurate theoretical frameworks, we hope to provide new insights into the treatment of clinical liver injury diseases.

Prevalence and incidence of MAFLD and associated anthropometric parameters among prepubertal children of the Shanghai Birth Cohort

BACKGROUND AND AIM

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common chronic liver disease in adolescent and adult population. However, the epidemiologic data of MAFLD in prepubertal children remain limited. This study aimed to investigate the prevalence and incidence of MAFLD and assess the role of anthropometric parameters in identifying and predicting MAFLD in this population.

METHODS

Children from the Shanghai Birth Cohort Study who underwent an 8-year follow-up with anthropometric measurements and transient elastography FibroScan-502 examination (M probe, Echosens, Paris, France) were enrolled. Some of them also completed a 5-year follow-up. Diagnosis of fatty liver disease (FLD) was based on the controlled attenuation parameter (CAP) value exceeding 248 dB/m, and MAFLD was defined as FLD combined with obesity or central obesity. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the diagnostic accuracy of anthropometric parameters for MAFLD.

RESULTS

A total of 848 children (431 boys) from the Shanghai Birth Cohort Study were followed up for 8 years, and among them, 385 children (189 boys) also participated in the 5-year follow-up. The prevalence of FLD and MAFLD at 5 years old was 3.90% and 0.52%, respectively, while at 8 years old, the prevalence rates increased to 5.07% for FLD and 3.42% for MAFLD. The 8-year-old children with MAFLD exhibited significantly higher weight, body mass index (BMI), chest circumference, waist circumference, hip circumference, waist-to-height ratio, waist-to-hip ratio, and liver stiffness measurement compared to those without MAFLD (all p < 0.05). The incidence rates of FLD and MAFLD at 8 years old, considering the 5-year follow-up data, were 3.78% (14/370) and 3.13% (12/383), respectively. Obese or centrally obese children at 5 years old had a higher incidence of FLD and MAFLD at the 8-year follow-up. Waist circumference and BMI showed significant associations with the presence and incidence of MAFLD, respectively, with the largest AUC values in ROC curve analysis. In addition, chest circumference was significantly associated with MAFLD in obese children.

CONCLUSION

This study provides insights into the incidence and prevalence of MAFLD in prepubertal children. It underscores the importance of anthropometric parameters in identifying and predicting MAFLD in this population. Further research encompassing a broader age range and incorporating these indicators and additional metabolic markers is necessary to enhance the understanding and management of MAFLD in children.

Updates in Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) in Children

The obesity epidemic is one of the major health concerns of the 21st century. Nonalcoholic fatty liver disease (NAFLD) is linked with the increased adiposity associated with obesity. NAFLD has become the most frequent cause of chronic liver disease in adults and children worldwide. Metabolic dysfunction-associated fatty liver disease (MAFLD) also known in children as pediatric fatty liver disease (PeFLD) type 2 has begun to supersede NAFLD as the preferred nomenclature in the pediatric population. Evidence suggests the etiology of MAFLD is multifactorial, related to the complex interplay of hormonal, nutritional, genetic, and environmental factors. Current limitations in accurate diagnostic biomarkers have rendered it a diagnosis of exclusion and it is important to exclude alternative or coexisting causes of PeFLD. Lifestyle changes and modifications remains the primary treatment modality in MAFLD in children. Weight loss of 7%-10% is described as reversing MAFLD in most patients. The Mediterranean diet also shows promise in reversing MAFLD. Pharmacological intervention is debatable in children, and though pediatric trials have not shown promise, other agents undergoing adult clinical trials show promise. This review outlines the latest evidence in pediatric MAFLD and its management.

Emerging role of nanotechnology in treatment of non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is a prevailing health challenge that requires urgent innovative interventions. This review explores the role of nanotechnology as a promising potential in the treatment of NAFLD. It delineates the limitations of the current management strategies for NAFLD and highlights the new nanotechnology-based treatments including nanoemulsions, liposomes, micelles, polymeric nanoparticles, nanogels, inorganic nanoparticles, and zinc oxide nanoparticles. Despite the optimism surrounding the nanotechnological approach, the review underscores the need to address the limitations such as technical challenges, potential toxicity, and ethical considerations that impede the practical application of nanotechnology in NAFLD management. It advocates for collaborative efforts from researchers, clinicians, ethicists, and policymakers to achieve safe, effective, and equitable nanotechnology-based treatments for NAFLD. See also Figure 1(Fig. 1).

Nutritional Approaches in Children with Overweight or Obesity and Hepatic Steatosis

Childhood obesity is a global public health problem. Worldwide, 41 million children under 5 years and 340 million children and adolescents between 5 and 19 years are overweight. In addition, the recent COVID-19 epidemic has further amplified this social phenomenon. Obesity is a condition associated with various comorbidities, such as nonalcoholic fatty liver disease (NAFLD). The pathophysiology of NAFLD in obesity is intricate and involves the interaction and dysregulation of several mechanisms, such as insulin resistance, cytokine signaling, and alteration of the gut microbiota. NAFLD is defined as the presence of hepatic steatosis in more than 5% of hepatocytes, evaluated by histological analysis. It can evolve from hepatic steatosis to steatohepatitis, fibrosis, cirrhosis, hepatocellular carcinoma, and end-stage liver failure. Body weight reduction through lifestyle modification remains the first-line intervention for the management of pediatric NAFLD. Indeed, studies suggest that diets low in fat and sugar and conversely rich in dietary fibers promote the improvement of metabolic parameters. This review aims to evaluate the existing relationship between obesity and NAFLD in the pediatric population and to assess the dietary patterns and nutritional supplementations that can be recommended to prevent and manage obesity and its comorbidities.

Correlation of the Pediatric Metabolic Index with NAFLD or MAFLD diagnosis, and serum adipokine levels in children

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is characterized by ectopic fat deposition in the liver. However, a recent classification of this condition, which also integrates the presence of coexisting metabolic disorders, termed Metabolic dysfunction Associated Fatty Liver Disease (MAFLD), has been proposed. NAFLD is increasingly common in early childhood, partly due to the increase in metabolic disease in this age. Thus, studying hepatic steatosis in the metabolic context has become important in this population as well. However, NAFLD, and thus MAFLD, diagnosis in children is challenging by the lack of non-invasive diagnostic tools comparable to the gold standard of hepatic biopsy. Recent studies have reported that the Pediatric Metabolic Index (PMI) could be a marker of insulin resistance and abnormal liver enzymes, but its association with NAFLD, MAFLD, or altered adipokines in these conditions has not been reported. The aim of this study is to evaluate the correlation between PMI with the diagnosis of NAFLD or MAFLD, together with serum levels of leptin and adiponectin, in school-age children.

METHODS

A cross sectional study was carried out in two hundred and twenty-three children without medical history of hypothyroidism, genetic, or chronic diseases. Anthropometry, liver ultrasound, and serum levels of lipids, leptin, and adiponectin were evaluated. The children were classified as having NAFLD or non-NAFLD, and a subgroup of MAFLD in the NAFLD group was analyzed. The PMI was calculated by the established formulas for age and gender.

RESULTS

PMI correlated positively with the presence and severity of NAFLD (r=0.62, p<0.001 and r= 0.79, p<0.001 respectively) and with the presence of MAFLD (r=0.62; p<0.001). Also, this index correlated positively with serum leptin levels (r=0.66; p<0.001) and negatively with serum adiponectin levels (r= -0.65; p<0.001). PMI showed to be a good predictor for diagnosing NAFLD in school-age children when performing a ROC curve analysis (AUROC=0.986, p< 0.0001).

CONCLUSION

PMI could be a useful tool for the early diagnosis of NAFLD or MAFLD in children. However, future studies are necessary to establish validated cut-off points for each population.

Fatty liver disease in children (MAFLD/PeFLD Type 2): unique classification considerations and challenges

In children, fatty liver disease is a group of disorders that often overlaps with inherited metabolic disorders (IMDs), which requires prompt diagnosis and specific management. Metabolic dysfunction-associated fatty liver disease (MAFLD) or, formerly, non-alcoholic fatty liver disease (NAFLD) is the hepatic component of a multisystemic disease that requires a positive criteria in metabolic dysfunction for diagnosis. However, in children, the diagnosis of MAFLD is one of the exclusions of an IMD [paediatric fatty liver disease (PeFLD) type 1] including the possibility that an IMD can be identified in the future following investigations that may be negative at the time. Therefore, while children with fatty liver with metabolic dysfunction could be classified as MAFLD (PeFLD type 2) and managed that way, those who do not fulfil the criteria for metabolic dysfunction should be considered separately bearing in mind the possibility of identifying a yet undiagnosed IMD (PeFLD type 3). This concept is ever more important in a world where MAFLD is the most common cause of liver disease in children and adolescents in whom about 7% are affected. The disease is only partially understood, and awareness is still lacking outside hepatology and gastroenterology. Despite its increasing pervasiveness, the management is far from a one-size-fits-all. Increasing complexities around the genetic, epigenetic, non-invasive modalities of assessment, psychosocial impacts, therapeutics, and natural history of the disease have meant that an individualised approach is required. This is where the challenge lies so that children with fatty liver are considered on their own merits. The purpose of this review is to give a clinical perspective of fatty liver disease in children with relevance to metabolic dysfunction.

Paediatric non-alcoholic fatty liver disease: an approach to pathological evaluation

Non-alcoholic fatty liver disease (NAFLD) is becoming an increasingly important healthcare issue along with the rising rates of obesity worldwide. It is the most common chronic liver disease in the paediatric population and the fastest growing indication for liver transplant in young adults. The pathogenesis is complex with contributions from multiple factors and genetic predisposition. While non-invasive laboratory tests and imaging modalities are being increasingly used, the liver biopsy continues to play a crucial role in the diagnosis and prognosis of NAFLD. Histologically, the assessment of paediatric fatty liver disease requires special considerations with respect to a periportal predominant pattern seen in prepubertal patients, as well as a different set of disease processes in the differential diagnosis. In this review, we provide a summary of current knowledge on the epidemiology, pathogenesis and clinical course of paediatric NAFLD as well as the clinical guidelines on diagnosis and management. We discuss the indications and limitations of liver biopsy, histological patterns seen in paediatric NAFLD, other entities to be considered in the differential diagnosis, and conclude with appropriate triaging of liver biopsies and essential elements of pathology reporting.

Fructose-1,6-bisphosphatase deficiency causes fatty liver disease and requires long-term hepatic follow-up

Liver disease, occurring during pediatric or adult age, is often of undetermined cause. Some cases are probably related to undiagnosed inherited metabolic disorders. Hepatic disorders associated with fructose-1,6-bisphosphatase deficiency, a gluconeogenesis defect, are not reported in the literature. These symptoms are mainly described during acute crises, and many reports do not mention them because hypoglycemia and hyperlactatemia are more frequently in the forefront. Herein, the liver manifestations of 18 patients affected with fructose-1,6-bisphosphatase deficiency are described and the corresponding literature is reviewed. Interestingly, all 18 patients had liver abnormalities either during follow-up (hepatomegaly [n = 8/18], elevation of transaminases [n = 6/15], bright liver [n = 7/11]) or during acute crises (hepatomegaly [n = 10/17], elevation of transaminases [n = 13/16], acute liver failure [n = 6/14], bright liver [n = 4/14]). Initial reports described cases of liver steatosis, when liver biopsy was necessary to confirm the diagnosis by an enzymatic study. There is no clear pathophysiological basis for this fatty liver disease but we postulate that endoplasmic reticulum stress and de novo lipogenesis activation could be key factors, as observed in FBP1 knockout mice. Liver steatosis may expose patients to severe long-term liver complications. As hypoglycemia becomes less frequent with age, most adult patients are no longer monitored by hepatologist. Signs of fructose-1,6-bisphosphatase deficiency may be subtle and can be missed in childhood. We suggest that fructose-1,6-bisphosphatase deficiency should be considered as an etiology of hepatic steatosis, and a liver monitoring protocol should be set up for these patients, during lifelong follow-up.

Xenobiotic-Induced Aggravation of Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD), which is often linked to obesity, encompasses a large spectrum of hepatic lesions, including simple fatty liver, steatohepatitis, cirrhosis and hepatocellular carcinoma. Besides nutritional and genetic factors, different xenobiotics such as pharmaceuticals and environmental toxicants are suspected to aggravate MAFLD in obese individuals. More specifically, pre-existing fatty liver or steatohepatitis may worsen, or fatty liver may progress faster to steatohepatitis in treated patients, or exposed individuals. The mechanisms whereby xenobiotics can aggravate MAFLD are still poorly understood and are currently under deep investigations. Nevertheless, previous studies pointed to the role of different metabolic pathways and cellular events such as activation of de novo lipogenesis and mitochondrial dysfunction, mostly associated with reactive oxygen species overproduction. This review presents the available data gathered with some prototypic compounds with a focus on corticosteroids and rosiglitazone for pharmaceuticals as well as bisphenol A and perfluorooctanoic acid for endocrine disruptors. Although not typically considered as a xenobiotic, ethanol is also discussed because its abuse has dire consequences on obese liver.

Defining paediatric metabolic (dysfunction)-associated fatty liver disease: an international expert consensus statement

The term non-alcoholic fatty liver disease (NAFLD), and its definition, have limitations for both adults and children. The definition is most problematic for children, for whom alcohol consumption is usually not a concern. This problematic definition has prompted a consensus to rename and redefine adult NAFLD associated with metabolic dysregulation to metabolic (dysfunction)-associated fatty liver disease (MAFLD). Similarities, distinctions, and differences exist in the causes, natural history, and prognosis of fatty liver diseases in children compared with adults. In this Viewpoint we, an international panel, propose an overarching framework for paediatric fatty liver diseases and an age-appropriate MAFLD definition based on sex and age percentiles. The framework recognises the possibility of other coexisting systemic fatty liver diseases in children. The new MAFLD diagnostic criteria provide paediatricians with a conceptual scaffold for disease diagnosis, risk stratification, and improved clinical and multidisciplinary care, and they align with a definition that is valid across the lifespan.

Pediatric vs. adult NAFLD to MAFLD transition: a welcome but tangled path

The term non-alcoholic fatty liver disease (NAFLD) appears unfitting both in adults and in children. As obesity and metabolic syndrome play a relevant pathogenic role, an international group of adults’ liver disease experts has proposed to rename this condition metabolic (dysfunction)-associated fatty liver disease (MAFLD). While this new more appropriate and useful definition has mostly been met with good reactions in adults, it may present a tangled path in pediatrics. Here we further stress the recommendations of the North American and the European Societies for Pediatric Gastroenterology, Hepatology and Nutrition that a hyperechogenic liver in a child affected by obesity or overweight with chronically elevated liver enzymes should not be assumed to have NAFLD only. Especially in those patients who are not in the classic age range or who have particularly severe laboratory anomalies, other genetic, metabolic (inborn errors of metabolism, IEM), endocrine, intestinal and hepatic pediatric-onset conditions, should in fact be excluded, particularly when response to a weight loss trial is not available. The term pediatric fatty liver disease (PeFLD) with three subtypes (1. contextual diagnosis of an IEM; 2. Metabolic (dysfunction)-associated fatty liver; 3. unknown cause of fatty liver) has recently been proposed aiming to separate true MAFLD from IEM and/or the other above mentioned conditions, which may be rare when considered individually but represent a large group when considered collectively. Although the cost-effectiveness ratio of this attitude is still indeterminate, it is likely that the advantage of the early identification of a specifically treatable pediatric-onset liver disease associated to/mimicking MAFLD would be rewarding.

Non-Alcoholic Fatty Liver Disease in Children

Background and Objectives: The prevalence of pediatric non-alcoholic fatty liver disease is increasing. A lot of new data are published regularly. Materials and Methods: Original clinical studies, review articles, and guidelines in children were searched for and the most relevant included in this review. Results: A total of 138 retrieved papers were classified into pathogenesis, epidemiology, diagnosis, and treatment. Pathogenesis is currently explained with the "multi hit hypothesis", with complex interactions of genetic and environmental factors which trigger inflammation in steatotic liver. The prevalence is rising. A diagnosis can be made with laboratory tests, imaging, and liver biopsy after the exclusion of other causes of liver steatosis. The mainstay of treatment is lifestyle modification consisting of dietary intervention and increased physical activity. The progression to liver cirrhosis can occur even in children. Conclusions: Non-alcoholic fatty liver disease in children is a part of a metabolic syndrome in the majority of patients. Due to its complex etiology and high prevalence, multidisciplinary teams, together with public health professionals, should be involved in its treatment.

Diagnosis and management of secondary causes of steatohepatitis

The term non-alcoholic fatty liver disease (NAFLD) was originally coined to describe hepatic fat deposition as part of the metabolic syndrome. However, a variety of rare hereditary liver and metabolic diseases, intestinal diseases, endocrine disorders and drugs may underlie, mimic, or aggravate NAFLD. In contrast to primary NAFLD, therapeutic interventions are available for many secondary causes of NAFLD. Accordingly, secondary causes of fatty liver disease should be considered during the diagnostic workup of patients with fatty liver disease, and treatment of the underlying disease should be started to halt disease progression. Common genetic variants in several genes involved in lipid handling and metabolism modulate the risk of progression from steatosis to fibrosis, cirrhosis and hepatocellular carcinoma development in NAFLD, alcohol-related liver disease and viral hepatitis. Hence, we speculate that genotyping of common risk variants for liver disease progression may be equally useful to gauge the likelihood of developing advanced liver disease in patients with secondary fatty liver disease.

SMN Depleted Mice Offer a Robust and Rapid Onset Model of Nonalcoholic Fatty Liver Disease

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is considered a health epidemic with potential devastating effects on the patients and the healthcare systems. Current preclinical models of NAFLD are invariably imperfect and generally take a long time to develop. A mouse model of survival motor neuron (SMN) depletion (Smn^2B/- mice) was recently shown to develop significant hepatic steatosis in less than 2 weeks from birth. The rapid onset of fatty liver in Smn^2B/- mice provides an opportunity to identify molecular markers of NAFLD. Here, we investigated whether Smn^2B/- mice display typical features of NAFLD/nonalcoholic steatohepatitis (NASH).

METHODS

Biochemical, histologic, electron microscopy, proteomic, and high-resolution respirometry were used.

RESULTS

The Smn^2B/- mice develop microvesicular steatohepatitis within 2 weeks, a feature prevented by AAV9-SMN gene therapy. Although fibrosis is not overtly apparent in histologic sections of the liver, there is molecular evidence of fibrogenesis and presence of stellate cell activation. The consequent liver damage arises from mitochondrial reactive oxygen species production and results in hepatic dysfunction in protein output, complement, coagulation, iron homeostasis, and insulin-like growth factor-1 metabolism. The NAFLD phenotype is likely due to non-esterified fatty acid overload from peripheral lipolysis subsequent to hyperglucagonemia compounded by reduced muscle use and insulin resistance. Despite the low hepatic mitochondrial content, isolated mitochondria show enhanced β-oxidation, likely as a compensatory response, resulting in the production of reactive oxygen species. In contrast to typical NAFLD/NASH, the Smn^2B/- mice lose weight because of their associated neurological condition (spinal muscular atrophy) and develop hypoglycemia.

CONCLUSIONS

The Smn^2B/- mice represent a good model of microvesicular steatohepatitis. Like other models, it is not representative of the complete NAFLD/NASH spectrum. Nevertheless, it offers a reliable, low-cost, early-onset model that is not dependent on diet to identify molecular players in NAFLD pathogenesis and can serve as one of the very few models of microvesicular steatohepatitis for both adult and pediatric populations.

Incidence of Nonalcoholic Fatty Liver Disease in Children: 2009-2018

BACKGROUND AND OBJECTIVES

In 2007, the American Academy of Pediatrics recommended that children with obesity should be screened for nonalcoholic fatty liver disease (NAFLD). Population epidemiology reveals that NAFLD is common in children; however, little is known about rates of clinical diagnosis. In this study, we aim to determine screening practices, annual incidence, and clinical characteristics of NAFLD in children within an integrated community health system.

METHODS

Using electronic health records, we identified patients newly diagnosed (aged 5-18) with NAFLD on the basis of diagnostic codes from the 9th and 10th revisions of the International Classification of Diseases. We calculated screening rates and annual incidence rates of NAFLD from January 1, 2009, to December 31, 2018.

RESULTS

In this study, we evaluated 7 884 844 patient-years. Screening was performed in 54.0% of children with obesity and 24.0% of children with overweight. The results revealed 36 658 children aged 9 to 18 with overweight or obesity and alanine aminotransferase >30 U/L. Of these children, 12.3% received further workup for NAFLD. The incidence of an NAFLD diagnosis significantly increased over time, with 36.0 per 100 000 in 2009 and 58.2 per 100 000 in 2018 (P < .0001).

CONCLUSIONS

Our study of a large integrated health care system in southern California revealed that the incidence of NAFLD in children is increasing, although many children may remain undiagnosed.

Moderate chronic ethanol consumption exerts beneficial effects on nonalcoholic fatty liver in mice fed a high-fat diet: possible role of higher formation of triglycerides enriched in monounsaturated fatty acids

PURPOSE

Several clinical studies suggested that light-to-moderate alcohol intake could alleviate nonalcoholic fatty liver disease (NAFLD), but the underlying mechanism is still poorly understood.

METHODS

Mice fed a high-fat diet (HFD) were submitted or not to moderate ethanol intake for 3 months (ca. 10 g/kg/day) via drinking water. Biochemical, analytical and transcriptomic analyses were performed in serum and liver.

RESULTS

Serum ethanol concentrations in ethanol-treated HFD mice comprised between 0.5 and 0.7 g/l throughout the experiment. NAFLD improvement was observed in ethanol-treated HFD mice as assessed by reduced serum transaminase activity. This was associated with less microvesicular and more macrovacuolar steatosis, the absence of apoptotic hepatocytes and a trend towards less fibrosis. Liver lipid analysis showed increased amounts of fatty acids incorporated in triglycerides and phospholipids, reduced proportion of palmitic acid in total lipids and higher desaturation index, thus suggesting enhanced stearoyl-coenzyme A desaturase activity. mRNA expression of several glycolytic and lipogenic enzymes was upregulated. Genome-wide expression profiling and gene set enrichment analysis revealed an overall downregulation of the expression of genes involved in collagen fibril organization and leukocyte chemotaxis and an overall upregulation of the expression of genes involved in oxidative phosphorylation and mitochondrial respiratory chain complex assembly. In addition, mRNA expression of several proteasome subunits was upregulated in ethanol-treated HFD mice.

CONCLUSIONS

Moderate chronic ethanol consumption may alleviate NAFLD by several mechanisms including the generation of non-toxic lipid species, reduced expression of profibrotic and proinflammatory genes, restoration of mitochondrial function and possible stimulation of proteasome activity.

Inborn errors of metabolism in the differential diagnosis of fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease across all age groups. Obesity, diabetes, and metabolic syndrome, are the primary causes that are closely linked with the development of NAFLD. However, in young children, rare inborn errors of metabolism are predominant secondary causes of NAFLD. Furthermore, inborn errors of metabolism causing hepatosteatosis are often misdiagnosed as NAFLD in adolescents and adults. Many inborn errors of metabolism are treatable disorders and therefore require special consideration. This review aims to summarize the basic characteristics and diagnostic clues of inborn errors of metabolism associated with fatty liver disease. A suggested clinical and laboratory diagnostic approach is also discussed.

Urinary thiodiglycolic acid is associated with increased risk of non-alcoholic fatty liver disease in children living near a petrochemical complex

BACKGROUND

Occupational and experimental studies have revealed that high vinyl chloride monomer (VCM) exposure is associated with non-alcoholic fatty liver disease (NAFLD). Epidemiological study reported that children living near a petrochemical complex have elevated exposure levels of urinary thiodiglycolic acid (TDGA), a potential VCM biomarker. However, no studies on the association of urinary TDGA exposure with NAFLD in children are available.

AIM

To assess the association of pediatric NAFLD with urinary TDGA exposure in school-aged children living near a petrochemical complex.

MATERIALS AND METHODS

In total, 261 school-aged children (aged 6-13 years) living near a petrochemical complex were recruited during October 2013 to September 2014. First morning spot urine was sampled for analyzing urinary TDGA through liquid chromatography-tandem mass spectrometry. Ultrasonography and serum alanine aminotransferase (ALT) were examined in each participant. NAFLD was diagnosed as recommended by the North American and European Society of Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN and ESPGHAN). Risk for NAFLD with urinary TDGA exposure in children was evaluated using a multivariate logistic regression model.

RESULTS

The percentage of children with NAFLDNASPGHAN and NAFLDESPGHAN were 9.6% and 11.5%, respectively. Median levels (μg/g creatinine) of urinary TDGA of children with NAFLDNASPGHAN (vs non-NAFLDNASPGHAN) and NAFLDESPGHAN (vs non-NAFLDESPGHAN) were 118.0 (vs 96.6) and 113.1 (vs 96.5), respectively. Participants in the highest urinary TDGA quartile (Q4: ≥160.0 μg/g creatinine) had a significantly increased risk (odds ratio [OR] = 4.95; 95% confidence interval [CI] = 1.15-21.38; P = 0.032) and dose-response trend (Ptrend = 0.045) for NAFLDNASPGHAN compared with those in the lowest urinary TDGA quartile (Q1: <35.4 μg/g creatinine) after adjustment for age, gender, BMI, triglycerides, HOMA-IR and distance of elementary schools from the petrochemical complex. Participants in the Q4 had borderline significantly increased risk (OR = 3.45; 95% CI = 0.89-13.42; P = 0.074) correlated with NAFLDESPGHAN compared with those in the Q1 after adjustment for confounders.

CONCLUSION

Our findings support the hypothesis that children exposed to higher urinary TDGA levels significantly increased pediatric NAFLD risk. Serum ALT levels can be a useful predictor for screening children's NAFLD in field studies. Large and longitudinal studies are warranted to elucidate the association.

Understanding susceptibility and targeting treatment in non-alcoholic fatty liver disease in children; moving the fulcrum

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of paediatric liver disease, affecting 10% of school-aged children and 44–70% of obese children and young people (CYP) in the western world. Encompassing a spectrum from simple steatosis to steatohepatitis and progressive fibrosis, the disease is rapidly becoming the most common indication for liver transplantation. The molecular pathogenesis of NAFLD remains only partially understood. Development and progression of NAFLD is influenced by genetic and nutritional factors, insulin resistance, oxidative stress, gut microbiome, bile acid metabolism and lipid/glucose handling and is closely associated with overweight and obesity. Lifestyle change is the only proven effective treatment for paediatric NAFLD, however this is difficult to achieve in many. Given that moderate or severe fibrosis is already present in 30–50% of children with NAFLD at the time of presentation, progression in CYP may be more rapid, though adequate outcome data do not yet exist in this cohort. CYP with NAFLD are an excellent population in which to study underlying mechanisms and interventions to correct disease progression as they are largely unaffected by other environmental influences such as alcohol and may represent the more severe end of the spectrum in terms of early onset. Undoubtedly genetic and epigenetic mechanisms determine a large proportion of susceptibility to the disease and potentially, identification of individuals at risk may allow for targeted therapy. This review with give a clinical perspective of paediatric NAFLD focused on identifying those at risk of progressive disease and what to consider in attempting to modify risk.

Psychosocial Issues in Pediatric Nonalcoholic Fatty Liver Disease

BACKGROUND

In recent years, the adoption of unhealthy dietary habits and a sedentary lifestyle has led to an alarming increase in the prevalence of non-alcoholic fatty liver disease (NAFLD) in pediatric populations. Hepatic steatosis is now considered the most common cause of chronic liver disease in children and adolescents and may progress to liver fibrosis and even cirrhosis, increasing long-term mortality rates. Apart from its severe medical co-morbidities, pediatric NAFLD is associated with a variety of psychosocial factors which act either as precipitants or consequences of the disease.

OBJECTIVE

Studying these parameters might expand our understanding of NAFLD pathogenesis and provide a framework for more effective management.

METHOD

In this context, we performed a literature review focusing on the associations of pediatric NAFLD with psychosocial parameters to detect and integrate the most recent data on this topic and provide a scaffold for further conceptualization and research.

RESULTS

There are a limited number of studies addressing issues of psychosocial functioning in children with NAFLD. Pediatric NAFLD is frequently accompanied by neuropsychiatric symptoms and poor quality of life and the level of impairment does not correlate with the degree of hepatic damage. In addition, mentally and intellectually-impaired youth appear at greater risk for developing liver steatosis.

CONCLUSIONS

Pediatric NAFLD is associated with psychosocial parameters in a bidirectional way. Further research is needed on NAFLD's psychosocial correlates and on the effect of treatment on patients' well-being.

Childhood and Adolescent Nonalcoholic Fatty Liver Disease: Is It Different from Adults?

Paediatric nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in childhood and adolescence. Although the condition is similar in many ways to NAFLD in adults, there are important differences in predisposition, presentation, differential diagnosis and potentially also in optimal management. Antenatal and early childhood exposures and the particular vulnerabilities to environmental influences in a growing child, present unique opportunities for intervention and modification of risk. The prevalence of significant fibrosis on biopsy in preadolescent children in the context of NAFLD should not be ignored, but the relevance of this fibrosis to long-term outcome is as yet unknown. The approach to children and adolescents with suspected NAFLD needs to include an assessment of risk factors in addition to exclusion of alternative or coexisting liver diseases. Liver biopsy is indicated for younger children and for those without clear predisposing factors leading to metabolic syndrome, also for those in whom significant fibrosis is suspected. The histology in children and adolescents differs from adults in whom type 2 NAFLD may be more prevalent, which is associated in turn with more significant fibrosis. Management in children and adolescents needs to focus on lifestyle intervention, which when weight loss is achieved, demonstrates excellent results in terms of resolution of disease. Appropriate intervention in childhood and adolescence may prove instrumental in avoiding the need for later transplantation while also decreasing all-cause mortality in these at-risk individuals.

Pediatric Fatty Liver and Obesity: Not Always Justa Matter of Non-Alcoholic Fatty Liver Disease

Obesity-related non-alcoholic fatty liver disease (NAFLD) represents the most common cause of pediatric liver disease due to overweight/obesity large-scale epidemics. In clinical practice, diagnosis is usually based on clinical features, blood tests, and liver imaging. Here, we underline the need to make a correct differential diagnosis for a number of genetic, metabolic, gastrointestinal, nutritional, endocrine, muscular, and systemic disorders, and for iatrogenic/viral/autoimmune hepatitis as well. This is all the more important for patients who are not in the NAFLD classical age range and for those for whom a satisfactory response of liver test abnormalities to weight loss after dietary counseling and physical activity measures cannot be obtained or verified due to poor compliance. A correct diagnosis may be life-saving, as some of these conditions which appear similar to NAFLD have a specific therapy. In this study, the characteristics of the main conditions which require consideration are summarized, and a practical diagnostic algorithm is discussed.