Redefining fatty liver disease: an international patient perspective

The Chinese Society of Hepatology position statement on the redefinition of fatty liver disease

Fatty liver disease associated with metabolic dysfunction is of increasing concern in mainland China, the world's most populous country. The incidence of fatty liver disease is highest in China, surpassing the incidence in European countries and the USA. An international consensus panel recently published an influential report recommending a novel definition of fatty liver disease associated with metabolic dysfunction. This recommendation includes a switch in name from non-alcoholic fatty liver disease (NAFLD) to metabolic (dysfunction)-associated fatty liver disease (MAFLD) and adoption of a set of positive criteria for disease diagnosis that are independent of alcohol intake or other liver diseases. Given the unique importance of this proposal, the Chinese Society of Hepatology (CSH) invited leading hepatologists and gastroenterologists representing their respective provinces and cities to reach consensus on alternative definitions for fatty liver disease from a national perspective. The CSH endorses the proposed change from NAFLD to MAFLD (supported by 95.45% of participants). We expect that the new definition will result in substantial improvements in health care for patients and advance disease awareness, public health policy, and political, scientific and funding outcomes for MAFLD in China.

Curcumin and Biochemical Parameters in Metabolic-Associated Fatty Liver Disease (MAFLD)-A Review

Metabolic-associated fatty liver disease (MAFLD), formerly non-alcoholic fatty liver disease (NAFLD), is characterized by excessive fat accumulation in hepatocytes. It is the most common chronic liver disease worldwide and is a significant public health problem. In the absence of pharmacological therapy, other treatments such as diet, physical activity, or supplementation are sought. Non-pharmacological therapies may include curcumin supplementation, which has been shown to have many health-promoting properties, including antioxidant, anti-inflammatory, and anti-cancer effects. For this reason, we reviewed available databases to analyze publications describing the effect of curcumin supplementation on biochemical parameters in MAFLD. Nine studies (eight RCTs and one CT) based solely on supplementation of patients with curcumin were included in this review. The results from the individual trials were varied and did not allow clear conclusions. Although they suggest that curcumin shows some potential in the treatment of MAFLD, further research is needed.

Incorporating fatty liver disease in multidisciplinary care and novel clinical trial designs for patients with metabolic diseases

With the global epidemics of obesity and associated conditions, including type 2 diabetes, metabolic dysfunction-associated fatty liver disease, chronic kidney disease, hypertension, stroke, cardiovascular disease, osteoporosis, cancer, and cognitive changes, the prevalence of multimorbidity is rapidly increasing worldwide. In this Review, a panel of international experts from across the spectrum of metabolic diseases come together to identify the challenges and provide perspectives on building a framework for a virtual primary care-driven, patient-centred, multidisciplinary model to deliver holistic care for patients with metabolic dysfunction-associated fatty liver disease and associated metabolic diseases. We focus on clinical care and innovative trial design for metabolic dysfunction-associated fatty liver disease and associated metabolic diseases. This work represents a call to action to promote collaboration and partnerships between stakeholders for improving the lives of people with, or at risk of, metabolic dysfunction-associated fatty liver disease and associated metabolic diseases.

Targeting the GPR119/incretin axis: a promising new therapy for metabolic-associated fatty liver disease

In the past decade, G protein-coupled receptors have emerged as drug targets, and their physiological and pathological effects have been extensively studied. Among these receptors, GPR119 is expressed in multiple organs, including the liver. It can be activated by a variety of endogenous and exogenous ligands. After GPR119 is activated, the cell secretes a variety of incretins, including glucagon-like peptide-1 and glucagon-like peptide-2, which may attenuate the metabolic dysfunction associated with fatty liver disease, including improving glucose and lipid metabolism, inhibiting inflammation, reducing appetite, and regulating the intestinal microbial system. GPR119 has been a potential therapeutic target for diabetes mellitus type 2 for many years, but its role in metabolic dysfunction associated fatty liver disease deserves further attention. In this review, we discuss relevant research and current progress in the physiology and pharmacology of the GPR119/incretin axis and speculate on the potential therapeutic role of this axis in metabolic dysfunction associated with fatty liver disease, which provides guidance for transforming experimental research into clinical applications.

The FibroScan-aspartate aminotransferase score can stratify the disease severity in a Japanese cohort with fatty liver diseases

This study aimed to prove that the FibroScan-aspartate aminotransferase (FAST) scores can be used to stratify disease severity in a Japanese cohort with fatty liver diseases [metabolic dysfunction-associated fatty liver disease (MAFLD) and nonalcoholic fatty liver disease (NAFLD)]. All the participants (n = 2254) underwent liver stiffness measurements and controlled attenuation parameter assessments. We compared the clinical characteristics of the patients with MAFLD and NAFLD using the FAST scores and explored the independent determinants of FAST scores ≥ 0.35, which indicated possible progressive disease. Overall, MAFLD was diagnosed in 789 patients (35.0%), while NAFLD was diagnosed in 618 (27.4%). The proportion of patients that had a condition that suggested progressive liver disease was higher in those with MAFLD than in those with NAFLD [68 (8.6%) vs 48 (7.7%)]. The area under the receiver-operating characteristic curve of the FAST score for diagnosing advanced fibrosis was 0.969 in MAFLD and 0.965 in NAFLD. Multivariate analyses determined that diabetes mellitus, alanine aminotransferase (ALT) levels, fatty liver index, and Fibrosis-4 index independently predict FAST scores ≥ 0.35 in patients with MAFLD. ALT levels had the strongest correlation with the FAST scores (p = 0.7817). The FAST score could stratify the disease severity in the Japanese cohort with fatty liver diseases.

Non-alcoholic fatty liver disease: a multisystem disease requiring a multidisciplinary and holistic approach

Non-alcoholic fatty liver disease (NAFLD) is a public health problem worldwide. This narrative Review provides an overview of the current literature to support the notion that NAFLD is a multisystem disease. Convincing evidence shows a strong association between NAFLD and the risk of developing multiple extrahepatic complications such as type 2 diabetes, cardiovascular disease (ie, the predominant cause of mortality in people with NAFLD), chronic kidney disease, and some types of extrahepatic malignancies. The magnitude of this risk parallels the severity of NAFLD (especially the stage of liver fibrosis). There are probably multiple underlying mechanisms by which NAFLD might increase the risk of cardiovascular disease, type 2 diabetes, and extrahepatic complications. Addressing the growing burden of NAFLD will require setting up a multidisciplinary working group and framework to progress and embrace novel collaborative ways of working to deliver holistic, person-centred care and management of people with NAFLD.

Role of Leptin in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD), which affects about a quarter of the global population, poses a substantial health and economic burden in all countries, yet there is no approved pharmacotherapy to treat this entity, nor well-established strategies for its diagnosis. Its prevalence has been rapidly driven by increased physical inactivity, in addition to excessive calorie intake compared to energy expenditure, affecting both adults and children. The increase in the number of cases, together with the higher morbimortality that this disease entails with respect to the general population, makes NAFLD a serious public health problem. Closely related to the development of this disease, there is a hormone derived from adipocytes, leptin, which is involved in energy homeostasis and lipid metabolism. Numerous studies have verified the relationship between persistent hyperleptinemia and the development of steatosis, fibrinogenesis and liver carcinogenesis. Therefore, further studies of the role of leptin in the NAFLD spectrum could represent an advance in the management of this set of diseases.

Targeting programmed cell death in metabolic dysfunction-associated fatty liver disease (MAFLD): a promising new therapy

Most currently recommended therapies for metabolic dysfunction-associated fatty liver disease (MAFLD) involve diet control and exercise therapy. We searched PubMed and compiled the most recent research into possible forms of programmed cell death in MAFLD, including apoptosis, necroptosis, autophagy, pyroptosis and ferroptosis. Here, we summarize the state of knowledge on the signaling mechanisms for each type and, based on their characteristics, discuss how they might be relevant in MAFLD-related pathological mechanisms. Although significant challenges exist in the translation of fundamental science into clinical therapy, this review should provide a theoretical basis for innovative MAFLD clinical treatment plans that target programmed cell death.

Perspectives on Precision Medicine Approaches to NAFLD Diagnosis and Management

Precision medicine defines the attempt to identify the most effective approaches for specific subsets of patients based on their genetic background, clinical features, and environmental factors. Nonalcoholic fatty liver disease (NAFLD) encompasses the alcohol-like spectrum of liver disorders (steatosis, steatohepatitis with/without fibrosis, and cirrhosis and hepatocellular carcinoma) in the nonalcoholic patient. Recently, disease renaming to MAFLD [metabolic (dysfunction)-associated fatty liver disease] and positive criteria for diagnosis have been proposed. This review article is specifically devoted to envisaging some clues that may be useful to implementing a precision medicine-oriented approach in research and clinical practice. To this end, we focus on how sex and reproductive status, genetics, intestinal microbiota diversity, endocrine and metabolic status, as well as physical activity may interact in determining NAFLD/MAFLD heterogeneity. All these factors should be considered in the individual patient with the aim of implementing an individualized therapeutic plan. The impact of considering NAFLD heterogeneity on the development of targeted therapies for NAFLD subgroups is also extensively discussed.

Gut Microbiota in Metabolic-associated Fatty Liver Disease and in Other Chronic Metabolic Diseases

The gut microbiome plays a key role in the health-disease balance in the human body. Although its composition is unique for each person and tends to remain stable throughout lifetime, it has been shown that certain bacterial patterns may be determining factors in the onset of certain chronic metabolic diseases, such as type 2 diabetes mellitus (T2DM), obesity, metabolic-associated fatty liver disease (MAFLD), and metabolic syndrome. The gut-liver axis embodies the close relationship between the gut and the liver; disturbance of the normal gut microbiota, also known as dysbiosis, may lead to a cascade of mechanisms that modify the epithelial properties and facilitate bacterial translocation. Regulation of gut microbiota is fundamental to maintaining gut integrity, as well as the bile acids composition. In the present review, we summarize the current knowledge regarding the microbiota, bile acids composition and their association with MAFLD, obesity, T2DM and metabolic syndrome.

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

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

From nonalcoholic fatty liver disease to metabolic-associated fatty liver disease: Big wave or ripple?

There is some dissatisfaction with the term "nonalcoholic fatty liver disease (NAFLD)," which overemphasizes alcohol and underemphasizes the importance of metabolic risk factors in this disease. Recently, a consensus recommended "metabolic (dysfunction)-associated fatty liver disease (MAFLD)" as a more appropriate term to describe fatty liver diseases (FLD) associated with metabolic dysfunction. During the definition change from NAFLD to MAFLD, subjects with FLD and metabolic abnormalities, together with other etiologies of liver diseases such as alcohol, virus, or medication who have been excluded from the NAFLD criteria, were added to the MAFLD criteria, while subjects with FLD but without metabolic abnormality, who have been included in the NAFLD criteria, were excluded from the MAFLD criteria. This means that there is an emphasis on the metabolic dysfunction in MAFLD which may underestimate the prognostic value of hepatic steatosis itself, whereas the MAFLD criteria might better identify subjects who are at a higher risk of hepatic or cardiovascular outcomes. However, non-metabolic risk NAFLD subjects who are excluded from the MAFLD criteria are missed from the diagnosis, and their potential risk can be the cause of future diseases. Although huge controversies remain, this review focused on summarizing recent studies that compared the clinical and prognostic characteristics between subjects with NAFLD and MAFLD.

MAFLD in Obese Children: A Challenging Definition

BACKGROUND

Recently, the new definition of Metabolic (dysfunction) associated fatty liver disease (MAFLD) has gained remarkable scientific interest. We aimed to evaluate the effectiveness of MAFLD definition in selecting obese children at higher cardiovascular risk.

METHODS

A total of 954 obese children and adolescents was retrospectively enrolled. Clinical, biochemical, and metabolic evaluations were performed. Hepatic steatosis was assessed by liver ultrasound. According to the metabolic status, the population was divided in three groups. Group 1 included obese patients without both non-alcoholic fatty liver disease (NAFLD) and metabolic dysregulation; group 2 included patients with obesity and NAFLD (then encompassing one MAFLD criterion); group 3 included patients with obesity, NAFLD and evidence of metabolic dysregulation (then encompassing more than 1 MAFLD criteria).

RESULTS

Patients of Group 3 showed a worse cardiometabolic profile, as also proven by the higher percentage of prediabetes (defined as the presence of impaired fasting glucose or impaired glucose tolerance) compared to other groups (p = 0.001).

CONCLUSIONS

MAFLD criteria in obese children seem to be less accurate in identifying patients having an intrinsic higher cardiometabolic risk. This suggests the need for a more accurate definition in the context of pediatric obesity.

Hepatic Dendritic Cells in the Development and Progression of Metabolic Steatohepatitis

Metabolic Associated Fatty liver disease (MAFLD) is a global health problem and represents the most common cause of chronic liver disease in the world. MAFLD spectrum goes from simple steatosis to cirrhosis, in between metabolic steatohepatitis with progressive fibrosis, which pathogenesis is not completely understood. Hence, the role of the immune system has become an important fact in the trigger of inflammatory cascades in metabolic steatohepatitis and in the activation of hepatic stellate cells (HSCs). Among, the more studied immune cells in the pathogenesis of MAFLD are macrophages, T cells, natural killer and dendritic cells. In particular, hepatic dendritic cells had recently attracted a special attention, with a dual role in the pathogenesis of MAFLD. These cells have the capacity to switch from a tolerant state to active state inducing an inflammatory cascade. Furthermore, these cells play a role in the lipid storage within the liver, having, thus providing a crucial nexus between inflammation and lipid metabolism. In this review, we will discuss the current knowledge on the dual role of dendritic cells in lipid accumulation, as wells as in the triggering of hepatic inflammation and hepatocytes cell death in metabolic steatohepatitis.

Mechanisms of Non-Alcoholic Fatty Liver Disease in the Metabolic Syndrome. A Narrative Review

Non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS) are two different entities sharing common clinical and physio-pathological features, with insulin resistance (IR) as the most relevant. Large evidence leads to consider it as a risk factor for cardiovascular disease, regardless of age, sex, smoking habit, cholesterolemia, and other elements of MS. Therapeutic strategies remain still unclear, but lifestyle modifications (diet, physical exercise, and weight loss) determine an improvement in IR, MS, and both clinical and histologic liver picture. NAFLD and IR are bidirectionally correlated and, consequently, the development of pre-diabetes and diabetes is the most direct consequence at the extrahepatic level. In turn, type 2 diabetes is a well-known risk factor for multiorgan damage, including an involvement of cardiovascular system, kidney and peripheral nervous system. The increased MS incidence worldwide, above all due to changes in diet and lifestyle, is associated with an equally significant increase in NAFLD, with a subsequent rise in both morbidity and mortality due to both metabolic, hepatic and cardiovascular diseases. Therefore, the slowdown in the increase of the "bad company" constituted by MS and NAFLD, with all the consequent direct and indirect costs, represents one of the main challenges for the National Health Systems.

NAFLD and Cardiovascular Diseases: Epidemiological, Mechanistic and Therapeutic Considerations

Overwhelming evidence suggests an association of cardiovascular disease (CVD) with non-alcoholic fatty liver disease (NAFLD); however, the underlying mechanisms remain largely speculative. It is, however, likely that common mechanisms contribute to the development of CVD and NAFLD, with lifestyle factors such as smoking, sedentary lifestyle with poor nutrition habits and physical inactivity being major candidates. These behavioral factors, on a predisposing genetic background, trigger changes in gut microbiota, inflammation, dyslipidemia and oxidative stress, leading to metabolic syndrome, diabetes and obesity as well as atherosclerosis. Treatment options to counteract both the progression and development of CVD and NAFLD include lifestyle interventions, optimal medical therapy of comorbid conditions and, as final possibility, bariatric surgery. As no causal pharmacotherapy of NAFLD is available, further research is urgently needed to address the unmet need of a growing population with NAFLD and CVD.

Relationship between the Metabolic Associated Fatty Liver Disease and Endometrial Thickness in Postmenopausal Women: A Cross-sectional Study in China

Objectives: To determine the relationship between the endometrial thickness (ET) and metabolic associated fatty liver disease (MAFLD) in the postmenopausal women who have a comprehensive health examination. Methods: This was a population-based, retrospective observational study of the prevalence of MAFLD in 8594 postmenopausal women with different ET in the Quality Control Center of Health Examination in Chongqing, China. Binary and multivariable logistic regression analyses were used to obtain odds ratios and 95% confidence intervals for patients of different ET with MAFLD after adjusting for age. Results: The incidences of MAFLD were 28.6% (1352), 30.3% (1058), 34.9% (133) in postmenopausal women with ET of < 3 mm, 3 mm ≤ & < 5 mm, and ≥ 5 mm, respectively. Compared with a baseline ET of less than 5.0 mm, the risk of MAFLD in patients with ET of ≥5.0 mm is higher (OR=1.291, 95% CI: 1.041-1.603, P<0.05). After adjustment for age, a statistically significant positive correlation was still observed. The increased prevalence of MAFLD in patients with ET of 3 mm ≤ &<5 mm (OR=1.110, 95% CI: 1.008-1.223) and ≥5 mm (OR=1.383, 95% CI: 1.109-1.724) achieved statistical significance, respectively. In addition, multiple logistic analyses controlling for age also confirmed the finding of positive correlation among body mass index (BMI) and ET. Conclusion: Our results suggest that there is a positive correlation between MAFLD and ET in postmenopausal women. In addition, increased BMI is also associated with an increased risk of thickened endometrium.

Genetic variation in the TLL1 gene is not associated with fibrosis in patients with metabolic associated fatty liver disease

Metabolic associated fatty liver disease (MAFLD) is the most prevalent liver disease in Western nations, with high heritability. A recent study of Japanese patients with the disease suggested that TLL1 rs17047200 is associated with fibrosis; whether a similar association is observed in Caucasian patients with MAFLD is unknown. We investigated the association of the TLL1 rs17047200 polymorphism with liver fibrosis in a cohort of Caucasian patients with MAFLD (n = 728). We also investigated whether TLL1 expression is altered during liver injury in humans, in murine models of fibrosis, and in in-vitro. While TLL1 expression is upregulated in the liver of humans with MAFLD and in mice, the rs17047200 variant was not associated with fibrosis or any other histological features, or with hepatic TLL1 expression. In conclusion, the TLL1 rs17047200 variant is not a risk variant for fibrosis in Caucasian patients with MAFLD. However, TLL1 could be involved in the pathogenesis of liver fibrosis.