Myostatin regulates the fibrogenic phenotype of hepatic stellate cells via c-jun N-terminal kinase activation

Association between non-alcoholic fatty liver disease and risk of sarcopenia: a systematic review and meta-analysis

OBJECTIVES

To determine the association of non-alcoholic fatty liver disease (NAFLD) with the incidence of sarcopenia.

DESIGN

Systematic review and meta-analysis of observational clinical studies.

SETTING AND PARTICIPANTS

Adults with NAFLD.

METHODS

Databases such as PubMed, Embase, Cochrane and Web of Science were searched for eligible studies published from the inception of each database up to 4 April 2023. All cross-sectional studies on the association between NAFLD and sarcopenia were included in this study. The quality of the included studies and risk of bias was assessed using the Agency for Healthcare Research and Quality checklist. STATA V.15.1 software was used for statistical analysis.

RESULTS

Of the 1524 retrieved articles, 24 were included in this review, involving 88 609 participants. Our findings showed that the prevalence of sarcopenia was higher in the NAFLD group than in the control group (pooled OR 1.74, 95% CI 1.39 to 2.17). In a subgroup analysis by region, patients with NAFLD showed an increased risk of sarcopenia (pooled OR 1.97, 95% CI 1.54 to 2.51) in the Asian group, whereas patients with NAFLD had no statistically significant association with the risk of sarcopenia in the American and European groups, with a pooled OR of 1.31 (95% CI 0.71 to 2.40) for the American group and a pooled OR of 0.99 (95% CI 0.21 to 4.69) for the European group. Similar results were observed in the sensitivity analysis, and no evidence of publication bias was observed.

CONCLUSIONS AND IMPLICATIONS

The current study indicated a significant positive correlation between NAFLD and sarcopenia, which may be affected by regional factors. This study provides the correlation basis for the relationship between NAFLD and sarcopenia and helps to find the quality strategy of sarcopenia targeting NAFLD.

Organoid-guided precision hepatology for metabolic liver disease

Metabolic dysfunction-associated steatotic liver disease affects millions of people worldwide. Progress towards a definitive cure has been incremental and treatment is currently limited to lifestyle modification. Hepatocyte-specific lipid accumulation is the main trigger of lipotoxic events, driving inflammation and fibrosis. The underlying pathology is extraordinarily heterogenous, and the manifestations of steatohepatitis are markedly influenced by metabolic communications across non-hepatic organs. Synthetic human tissue models have emerged as powerful platforms to better capture the mechanistic diversity in disease progression, while preserving person-specific genetic traits. In this review, we will outline current research efforts focused on integrating multiple synthetic tissue models of key metabolic organs, with an emphasis on organoid-based systems. By combining functional genomics and population-scale en masse profiling methodologies, human tissues derived from patients can provide insights into personalised genetic, transcriptional, biochemical, and metabolic states. These collective efforts will advance our understanding of steatohepatitis and guide the development of rational solutions for mechanism-directed diagnostic and therapeutic investigation.

Probiotics as Potential Therapeutic Agents: Safeguarding Skeletal Muscle against Alcohol-Induced Damage through the Gut-Liver-Muscle Axis

Probiotics have shown the potential to counteract the loss of muscle mass, reduce physical fatigue, and mitigate inflammatory response following intense exercise, although the mechanisms by which they work are not very clear. The objective of this review is to describe the main harmful effects of alcohol on skeletal muscle and to provide important strategies based on the use of probiotics. The excessive consumption of alcohol is a worldwide problem and has been shown to be crucial in the progression of alcoholic liver disease (ALD), for which, to date, the only therapy available is lifestyle modification, including cessation of drinking. In ALD, alcohol contributes significantly to the loss of skeletal muscle, and also to changes in the intestinal microbiota, which are the basis for a series of problems related to the onset of sarcopenia. Some of the main effects of alcohol on the skeletal muscle are described in this review, with particular emphasis on the "gut-liver-muscle axis", which seems to be the primary cause of a series of muscle dysfunctions related to the onset of ALD. The modulation of the intestinal microbiota through probiotics utilization has appeared to be crucial in mitigating the muscle damage induced by the high amounts of alcohol consumed.

A nomogram based on psoas muscle index predicting long-term cirrhosis incidence in non-cirrhotic patients with HBV-related acute‑on‑chronic liver failure

There is a lack of scoring system to predict the occurrence of cirrhosis in individuals with acute-on-chronic liver failure (ACLF) in the absence of cirrhosis. The goal of this study was to develop a psoas muscle index (PMI)-based nomogram for cirrhosis risk in non-cirrhotic patients with HBV-related ACLF. We included 274 non-cirrhotic HBV-ACLF patients who were randomly assigned to training and validation groups. Logistic analyses were performed to identify risk factors for cirrhosis. A nomogram was then constructed. The predictive performance of the nomogram was assessed using the area under the receiver operating characteristic curve (AUROC), calibration curve, and decision curve analysis (DCA). During the 360-day follow-up, 44.5% (122/274) of non-cirrhotic HBV-ACLF patients developed cirrhosis. A higher PMI at the L3 level was correlated with a decreased risk of long-term cirrhosis occurrence (OR 0.677, 95% CI 0.518-0.885, P = 0.004). The nomogram incorporating PMI, age, neutrophil-to-lymphocyte ratio (NLR), and international normalized ratio (INR), indicated satisfactory predictive performance for cirrhosis risk stratification in ACLF population. The nomograms had an AUROC of 0.812 (95% CI 0.747-0.866) and 0.824 (95% CI 0.730-0.896) in the training and validation cohorts, respectively. The calibration curves displayed excellent predictive accuracy of the nomogram in both sets. In both cohorts, the DCA verified the nomogram's clinical efficacy. In non-cirrhotic HBV-ACLF patients, a greater PMI appears to protect against long-term cirrhosis occurrence. Strong predictive performance has been demonstrated by PMI-based nomograms in assessing the likelihood of 1-year cirrhosis in those with HBV-ACLF.

Myokines: Crosstalk and Consequences on Liver Physiopathology

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease mainly characterized by the hepatic accumulation of lipid inducing a deregulation of β-oxidation. Its advanced form is non-alcoholic steatohepatitis (NASH), which, in addition to lipid accumulation, induces hepatocellular damage, oxidative stress and fibrosis that can progress to cirrhosis and to its final stage: hepatocellular carcinoma (HCC). To date, no specific therapeutic treatment exists. The implications of organ crosstalk have been highlighted in many metabolic disorders, such as diabetes, metabolic-associated liver diseases and obesity. Skeletal muscle, in addition to its role as a reservoir and consumer of energy and carbohydrate metabolism, is involved in this inter-organs’ communication through different secreted products: myokines, exosomes and enzymes, for example. Interestingly, resistance exercise has been shown to have a beneficial impact on different metabolic pathways, such as lipid oxidation in different organs through their secreted products. In this review, we will mainly focus on myokines and their effects on non-alcoholic fatty liver disease, and their complication: non-alcoholic steatohepatitis and HCC.

Serum Myostatin among Excessive Drinkers

Myostatin acts as a negative regulator of muscle growth. Its effect on fat mass is subject to debate. Among alcoholics, there is a high prevalence of muscle atrophy, and increased fat deposition has been also described in these patients. Myostatin could be involved in these alterations, but its relationships with body composition have been scarcely studied in alcoholic patients. To analyze the behavior of myostatin among alcoholics and its relationship with alcohol intake, liver function, and body composition. We investigated serum myostatin in 59 male patients and 18 controls. Patients were all heavy drinkers admitted with organic complications related to excessive ethanol ingestion. Densitometry analysis was used to assess body composition in 46 patients. Handgrip was assessed in 51 patients. Patients showed lower myostatin values than controls (Z = 3.80; p < 0.001). There was a significant relationship between myostatin and fat at the right leg (ρ = 0.32; p = 0.028), left leg (ρ = 0.32; p = 0.028), trunk (ρ = 0.31, p = 0.038), total fat proport ion (ρ = 0.33, p = 0.026), and gynecoid fat distribution (ρ = 0.40, p = 0.006) but not with lean mass (total lean ρ = 0.07; p = 0.63; trunk lean ρ = 0.03; p = 0.85; lower limbs ρ = 0.08; p = 0.58; upper limbs ρ = 0.04 p = 0.82; android ρ = 0.02; p = 0.88, or gynoid lean mass ρ = 0.20; p = 0.19). In total, 80.43% of patients showed at least one criterion of osteosarcopenic adiposity (OSA). Myostatin was related to OSA obesity. We also observed higher myostatin values among patients with body mass index > 30 kg/m². Serum myostatin was lower among excessive drinkers, and it was related to increased fat deposition among these patients but not to lean mass, handgrip, or bone mineral density.

Interaction between sarcopenia and nonalcoholic fatty liver disease

Sarcopenia and nonalcoholic fatty liver disease (NAFLD) are common health problems related to aging. Despite the differences in their diagnostic methods, several cross-sectional and longitudinal studies have revealed the close link between sarcopenia and NAFLD. Sarcopenia and NAFLD are linked by several shared pathogenetic mechanisms, including insulin resistance, hormonal imbalance, systemic inflammation, myostatin and adiponectin dysregulation, nutritional deficiencies, and physical inactivity, thus implicating a bidirectional relationship between sarcopenia and NAFLD. However, there is not sufficient data to support a direct causal relationship between sarcopenia and NAFLD. Moreover, it is currently difficult to conclude whether sarcopenia is a risk factor for nonalcoholic steatohepatitis (NASH) or is a consequence of NASH. Therefore, this review intends to touch on the shared common mechanisms and the bidirectional relationship between sarcopenia and NAFLD.

Skeletal muscle mass index as a predictor of long-term cirrhosis onset in young non-cirrhotic males with acute-on-chronic liver failure

Background

The relationship between skeletal muscle mass index (SMI) and cirrhosis incidence in patients with non-cirrhotic acute-on-chronic (ACLF) has not been clarified. This study aimed to assess the predictive value of SMI on the incidence of long-term cirrhosis in male non-cirrhotic ACLF patients.

Materials and methods

Male ACLF patients who were free of liver cirrhosis were retrospectively included in this study. Univariate and multivariate logistic analyses were conducted to determine the risk factors for the long-term (1-year) development of cirrhosis. The receiver operating characteristic curves (ROC) were used to assess the ability of SMI levels to predict the incidence of cirrhosis. Restricted triple spline (RCS) described the dose-response relationship between SMI and the risk of cirrhosis. Subgroup analysis was stratified by age (≤ 40 years and > 40 years).

Results

A total of 230 subjects were included in this study, of whom 45.2% (104/230) were diagnosed with cirrhosis within 360 days. Patients who progressed to cirrhosis had a lower SMI [46.1 ± 6.9 versus 49.2 ± 6.5 cm²/m², P = 0.001] and a higher proportion of sarcopenia (19.2% versus 6.3%, P = 0.003). In multivariate logistic regression, SMI remained a protective agent against 360-days progression to cirrhosis in males with ACLF after adjustment (OR 0.950, 95% CI: 0.908-0.994, P < 0.05). SMI exerted a non-linear dose-dependent effect on the risk of cirrhosis. The area under the ROC curve (AUC) for the L3-SMI to predict the incidence of cirrhosis in male non-cirrhotic ACLF patients was 0.636 (P < 0.001). We observed significant differences in SMI among male ACLF patients in different age groups. Further subgroup analysis by age revealed that lower SMI was associated with the 1-year incidence of cirrhosis in male ACLF patients aged less than 40 years (OR 0.908, 95% CI: 0.842-0.979, P < 0.05), whereas SMI did not affect the 1-year risk of cirrhosis in older subjects (age > 40 years).

Conclusion

A higher SMI represents an independent protective factor for developing long-term cirrhosis in male ACLF patients who do not experience cirrhosis, especially in those under 40 years of age.

Metabolic mechanisms for and treatment of NAFLD or NASH occurring after liver transplantation

The rising tide of non-alcoholic fatty liver disease (NAFLD) associated with the obesity epidemic is a major health concern worldwide. NAFLD - specifically its more advanced form, non-alcoholic steatohepatitis (NASH)-related cirrhosis - is now the fastest growing indication for liver transplantation in the USA and Europe. Although the short-term and mid-term overall survival rates of patients who receive a liver transplant for NASH-related cirrhosis are essentially similar to those of patients who receive a transplant for other liver indications, recipients with NASH-related cirrhosis have an increased risk of waiting-list mortality and of developing recurrent liver disease and cardiometabolic complications in the longer term after liver transplantation. This Review provides a brief overview of the epidemiology of NAFLD and NASH and the occurrence of NAFLD or NASH in patients after liver transplantation for NASH and other liver indications. It also discusses the putative metabolic mechanisms underlying the emergence of NAFLD or NASH after liver transplantation as well as optimal therapeutic approaches for recipients of liver transplants, including the management of cardiometabolic comorbidities, tailored immunosuppression, lifestyle changes and pharmacotherapy for NAFLD.

Non-alcoholic fatty liver disease-related fibrosis and sarcopenia: An altered liver-muscle crosstalk leading to increased mortality risk

In the last few decades, the loss of skeletal muscle mass and function, known as sarcopenia, has significantly increased in prevalence, becoming a major global public health concern. On the other hand, the prevalence of non-alcoholic fatty liver disease (NAFLD) has also reached pandemic proportions, constituting the leading cause of hepatic fibrosis worldwide. Remarkably, while sarcopenia and NAFLD-related fibrosis are independently associated with all-cause mortality, the combination of both conditions entails a greater risk for all-cause and cardiac-specific mortality. Interestingly, both sarcopenia and NAFLD-related fibrosis share common pathophysiological pathways, including insulin resistance, chronic inflammation, hyperammonemia, alterations in the regulation of myokines, sex hormones and growth hormone/insulin-like growth factor-1 signaling, which may explain reciprocal connections between these two disorders. Additional contributing factors, such as the gut microbiome, may also play a role in this relationship. In skeletal muscle, phosphatidylinositol 3-kinase/Akt and myostatin signaling are the central anabolic and catabolic pathways, respectively, and the imbalance between them can lead to muscle wasting in patients with NAFLD-related fibrosis. In this review, we summarize the bidirectional influence between NAFLD-related fibrosis and sarcopenia, highlighting the main potential mechanisms involved in this complex crosstalk, and we discuss the synergistic effects of both conditions in overall and cardiovascular mortality.

Myostatin/Activin Receptor Ligands in Muscle and the Development Status of Attenuating Drugs

Muscle wasting disease indications are among the most debilitating and often deadly noncommunicable disease states. As a comorbidity, muscle wasting is associated with different neuromuscular diseases and myopathies, cancer, heart failure, chronic pulmonary and renal diseases, peripheral neuropathies, inflammatory disorders, and, of course, musculoskeletal injuries. Current treatment strategies are relatively ineffective and can at best only limit the rate of muscle degeneration. This includes nutritional supplementation and appetite stimulants as well as immunosuppressants capable of exacerbating muscle loss. Arguably, the most promising treatments in development attempt to disrupt myostatin and activin receptor signaling because these circulating factors are potent inhibitors of muscle growth and regulators of muscle progenitor cell differentiation. Indeed, several studies demonstrated the clinical potential of "inhibiting the inhibitors," increasing muscle cell protein synthesis, decreasing degradation, enhancing mitochondrial biogenesis, and preserving muscle function. Such changes can prevent muscle wasting in various disease animal models yet many drugs targeting this pathway failed during clinical trials, some from serious treatment-related adverse events and off-target interactions. More often, however, failures resulted from the inability to improve muscle function despite preserving muscle mass. Drugs still in development include antibodies and gene therapeutics, all with different targets and thus, safety, efficacy, and proposed use profiles. Each is unique in design and, if successful, could revolutionize the treatment of both acute and chronic muscle wasting. They could also be used in combination with other developing therapeutics for related muscle pathologies or even metabolic diseases.

Impact of Sarcopenia on the Severity of the Liver Damage in Patients With Non-alcoholic Fatty Liver Disease

An extensive body of the literature shows a strong interrelationship between the pathogenic pathways of non-alcoholic fatty liver disease (NAFLD) and sarcopenia through the muscle-liver-adipose tissue axis. NAFLD is one of the leading causes of chronic liver diseases (CLD) affecting more than one-quarter of the general population worldwide. The disease severity spectrum ranges from simple steatosis to non-alcoholic steatohepatitis (NASH), cirrhosis, and its complications: end-stage chronic liver disease and hepatocellular carcinoma. Sarcopenia, defined as a progressive loss of the skeletal muscle mass, reduces physical performances, is associated with metabolic dysfunction and, possibly, has a causative role in NAFLD pathogenesis. Muscle mass is a key determinant of the whole-body insulin-mediated glucose metabolism and impacts fatty liver oxidation and energy homeostasis. These mechanisms drive the accumulation of ectopic fat both in the liver (steatosis, fatty liver) and in the muscle (myosteatosis). Myosteatosis rather than the muscle mass per se, seems to be closely associated with the severity of the liver injury. Sarcopenic obesity is a recently described entity which associates both sarcopenia and obesity and may trigger worse clinical outcomes including hepatic fibrosis progression and musculoskeletal disabilities. Furthermore, the muscle-liver-adipose tissue axis has a pivotal role in changes of the body composition, resulting in a distinct clinical phenotype that enables the identification of the "sarcopenic NAFLD phenotype." This review aims to bring some light into the complex relationship between sarcopenia and NAFLD and critically discuss the key mechanisms linking NAFLD to sarcopenia, as well as some of the clinical consequences associated with the coexistence of these two entities: the impact of body composition phenotypes on muscle morphology, the concept of sarcopenic obesity, the relationship between sarcopenia and the severity of the liver damage and finally, the future directions and the existing gaps in the knowledge.

Non-Alcoholic Steatohepatitis (NASH) and Organokines: What Is Now and What Will Be in the Future

Non-alcoholic steatohepatitis (NASH) is characterized by steatosis, lobular inflammation, and enlargement of the diameter of hepatocytes (ballooning hepatocytes), with or without fibrosis. It affects 20% of patients with non-alcoholic fatty liver disease (NAFLD). Due to liver dysfunction and the numerous metabolic changes that commonly accompany the condition (obesity, insulin resistance, type 2 diabetes, and metabolic syndrome), the secretion of organokines is modified, which may contribute to the pathogenesis or progression of the disease. In this sense, this study aimed to perform a review of the role of organokines in NASH. Thus, by combining descriptors such as NASH, organokines, oxidative stress, inflammation, insulin resistance, and dyslipidemia, a search was carried out in the EMBASE, MEDLINE-PubMed, and Cochrane databases of articles published in the last ten years. Insulin resistance, inflammation and mitochondrial dysfunction, fructose, and intestinal microbiota were factors identified as participating in the genesis and progression of NASH. Changes in the pattern of organokines secretion (adipokines, myokines, hepatokines, and osteokines) directly or indirectly contribute to aggravating the condition or compromise homeostasis. Thus, further studies involving skeletal muscle, adipose, bone, and liver tissue as endocrine organs are essential to better understand the modulation of organokines involved in the pathogenesis of NASH to advance in the treatment of this disease.

Myostatin: Basic biology to clinical application

Myostatin is a member of the transforming growth factor (TGF)-β superfamily. It is expressed by animal and human skeletal muscle cells where it limits muscle growth and promotes protein breakdown. Its effects are influenced by complex mechanisms including transcriptional and epigenetic regulation and modulation by extracellular binding proteins. Due to its actions in promoting muscle atrophy and cachexia, myostatin has been investigated as a promising therapeutic target to counteract muscle mass loss in experimental models and patients affected by different muscle-wasting conditions. Moreover, growing evidence indicates that myostatin, beyond to regulate skeletal muscle growth, may have a role in many physiologic and pathologic processes, such as obesity, insulin resistance, cardiovascular and chronic kidney disease. In this chapter, we review myostatin biology, including intracellular and extracellular regulatory pathways, and the role of myostatin in modulating physiologic processes, such as muscle growth and aging. Moreover, we discuss the most relevant experimental and clinical evidence supporting the extra-muscle effects of myostatin. Finally, we consider the main strategies developed and tested to inhibit myostatin in clinical trials and discuss the limits and future perspectives of the research on myostatin.

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.

Clinical impact of sexual dimorphism in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)

NAFLD/NASH is a sex-dimorphic disease, with a general higher prevalence in men. Women are at reduced risk of NAFLD compared to men in fertile age, whereas after menopause women have a comparable prevalence of NAFLD as men. Indeed, sexual category, sex hormones and gender habits interact with numerous NAFLD factors including cytokines, stress and environmental factors and alter the risk profiles and phenotypes of NAFLD. In the present review, we summarized the last findings about the influence of sex on epidemiology, pathogenesis, progression in cirrhosis, indication for liver transplantation and alternative therapies, including lifestyle modification and pharmacological strategies. We are confident that an appropriate consideration of sex, age, hormonal status and sociocultural gender differences will lead to a better understanding of sex differences in NAFLD risk, therapeutic targets and treatment responses and will aid in achieving sex-specific personalized therapies.

Myostatin as a fibroblast-activating factor impacts on postoperative outcome in patients with hepatocellular carcinoma

AIM

In patients with liver cirrhosis, high levels of serum myostatin are associated with poor prognosis. We aimed to clarify the influence of myostatin on the prognosis of patients with non-alcoholic fatty liver disease-hepatocellular carcinoma (NAFLD-HCC) without cirrhosis and on the progression of liver fibrosis.

METHODS

Serum myostatin levels were evaluated in 234 patients who underwent primary surgical resection for single HCC. To clarify the impact of myostatin on liver fibrosis, we established human primary liver fibroblasts from resected livers, and cultured them in the presence of myostatin.

RESULTS

The median age was 67.4 years, the median L3 skeletal muscle mass index was 44.4 cm² /m² , and the median body mass index was 23.4 kg/m² . Eighty-two (35.0%) patients had sarcopenia (L3 skeletal muscle mass index: men <42, women <38 cm² /m² ). The etiologies of liver disease were hepatitis B virus (n = 61), hepatitis C virus (n = 86), and non-B non-C hepatitis (n = 87) including NAFLD (n = 74). High preoperative serum myostatin and vascular invasion were independent predictors of poor overall survival (OS). High serum myostatin was associated with poor OS in patients with no sarcopenia (n = 152). In patients without advanced liver fibrosis (Fibrosis stage, 0-2; n = 58), high levels of serum myostatin were also associated with poor OS, regardless of sarcopenia. Serum myostatin levels were increased with the progression of liver fibrosis. Liver fibroblasts were activated and produced collagen following stimulation with myostatin.

CONCLUSIONS

In patients with NAFLD-HCC without advanced liver fibrosis, high levels of serum myostatin were associated with poor OS. Myostatin activated primary fibroblasts and stimulated collagen production.

Deregulation of Secreted Frizzled-Related Protein 5 in Nonalcoholic Fatty Liver Disease Associated with Obesity

Secreted frizzled-related protein 5 (SFRP5), an antagonist of the noncanonical WNT pathway, has a controversial role in liver disease. The aim of this study was to analyze the role of SFRP5 and the noncanonical WNT pathway in nonalcoholic fatty liver disease (NAFLD). Plasma SFRP5 levels were determined by ELISA in women with normal weight (NW; n = 20) and morbid obesity (MO; n = 69). Women with MO were subclassified according to hepatic histology into normal liver (NL; n = 28), NAFLD (n = 41) (simple steatosis (SS; n = 24), and nonalcoholic steatohepatitis (NASH; n = 17)). We used RT-qPCR to evaluate the hepatic mRNA expression of SFRP5, WNT5A, and JNK in women with MO. SFRP5 levels were lower in NW than in MO patients who underwent a very low-calorie diet before surgery. Hepatic SFRP5 mRNA expression was higher in SS than in NL or NASH; additionally, patients with hepatic inflammation or ballooning presented lower SFRP5 abundance. WNT5A and JNK expression was enhanced in NAFLD compared with NL. In conclusion, circulating SFRP5 levels depend on the diet, and hepatic SFRP5 seems to have a protective role in the first steps of NAFLD; however, SFRP5 could be deregulated in an advanced stage while WNT5A and JNK are activated, promoting liver damage.

Arm lean mass determined by dual-energy X-ray absorptiometry is superior to characterize skeletal muscle and predict sarcopenia-related mortality in cirrhosis

Sarcopenia worsens survival in patients with advanced liver disease including cirrhosis. In this study, we aimed to characterize skeletal muscle status by dual-energy X-ray absorptiometry (DXA) in patients with cirrhosis and examine the association between different skeletal muscle compartments and mortality. We included 231 men and 84 women (Child A, B, and C) with cirrhosis and 315 healthy matched controls (231 men and 84 women). Body composition was assessed with DXA. Appendicular skeletal muscle index (ASMI), arms index (AI), and legs index (LI) were calculated by normalizing lean mass to height squared. Low ASMI was defined as ASMI < 7.0 kg/m² in men and <5.5 kg/m² in women. Biochemical and hemodynamic data were recorded for cirrhotic patients and mortality data retrieved from registers. Low ASMI was more prevalent in both men (49%) and women (43%) with cirrhosis compared with healthy men (8%) and women (5%) (P < 0.001). ASMI and LI were lowest in Child B, whereas AI decreased gradually with advancing Child class. ASMI was inversely associated with mortality in men [HR = 0.74 (0.59-0.93), P < 0.01], and this was mainly driven by AI [HR = 0.37 (0.18-0.71), P < 0.01]. AI showed closer association than ASMI or LI to both the severity of liver disease and to mortality, which may be due to increasing prevalence of leg edema with disease progression in this population. Determination of arm lean mass may add information on survival in patients with cirrhosis.NEW & NOTEWORTHY Sarcopenia increases mortality in patients with end-stage liver disease. We show that arm lean mass determined by dual-energy X-ray absorptiometry is a better marker than the traditional appendicular skeletal muscle mass when predicting sarcopenia-related mortality in patients with cirrhosis of different severity. The findings add to the dispute about the optimal method for repeated assessments of skeletal muscle status in patients with cirrhosis and may have implications for clinical decision making.

The Impact of Dysmetabolic Sarcopenia Among Insulin Sensitive Tissues: A Narrative Review

Sarcopenia is a common muscular affection among elderly individuals. More recently, it has been recognized as the skeletal muscle (SM) expression of the metabolic syndrome. The prevalence of sarcopenia is increasing along with visceral obesity, to which it is tightly associated. Nonetheless, it is a still underreported entity by clinicians, despite the worsening in disease burden and reduced patient quality of life. Recognition of sarcopenia is clinically challenging, and variability in study populations and diagnostic methods across the clinical studies makes it hard to reach a strong evidence. Impaired insulin activity in SM is responsible for the altered molecular pathways and clinical manifestations of sarcopenia, which is morphologically expressed by myosteatosis. Lipotoxicity, oxidative stress and adipose tissue-derived inflammation lead to both alterations in glucose disposal and protein synthesis in SM, with raising insulin resistance (IR) and SM atrophy. In particular, hyperleptinemia and leptin resistance interfere directly with SM activity, but also with the release of Growth Hormone from the hypohysis, leading to a lack in its anabolic effect on SM. Moreover, sarcopenia is independently associated to liver fibrosis in Non-Alcoholic Fatty Liver Disease (NAFLD), which in turn worsens SM functionality through the secretion of proinflammatory heptokines. The cross-talk between the liver and SM in the IR setting is of crucial relevance, given the high prevalence of NAFLD and the reciprocal impact of insulin-sensitive tissues on the overall disease burden. Along with the efforts of non-invasive diagnostic approaches, irisin and myostatin are two myokines currently evaluated as potential biomarkers for diagnosis and prognostication. Decreased irisin levels seem to be potentially associated to sarcopenia, whereas increased myostatin has shown to negatively impact on sarcopenia in pre-clinical studies. Gene variants in irisin have been explored with regard to the impact on the liver disease phenotype, with conflicting results. The gut-muscle axis has gain relevance with the evidence that insulin resistance-derived gut dysbiosis is responsible for increased endotoxemia and reduction in short-chain free fatty acids, directly affecting and predisposing to sarcopenia. Based on the current evidence, more efforts are needed to increase awareness and improve the management of sarcopenic patients.

Aerobic Exercise in the Management of Metabolic Dysfunction Associated Fatty Liver Disease

Sedentarism is the pandemic of modern times. It is associated with several medical conditions including obesity, type 2 diabetes mellitus, cardiovascular diseases and also liver disease, particularly metabolic dysfunction associated fatty liver disease (MAFLD). In an era when MAFLD is the most prevalent chronic liver disease worldwide, whilst no pharmacological therapy has been approved for it, exercise has proved to be effective in improving liver steatosis. Interestingly, exercise decreases liver fat even in the absence of weight loss. The challenge for the clinician is to motivate the obese patient with MAFLD, and associated co-morbidities, who has crystallized a sedentary behavior, at times when every need is at the distance of a click on the Internet, and the entire world can be visited behind a screen. In this review, the aggregate evidence on the mechanisms and effects of exercise in the management of MAFLD is summarized, with simple recommendations for everyday clinical practice.

Harnessing Muscle-Liver Crosstalk to Treat Nonalcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) has reached epidemic proportions, affecting an estimated one-quarter of the world's adult population. Multiple organ systems have been implicated in the pathophysiology of NAFLD; however, the role of skeletal muscle has until recently been largely overlooked. A growing body of evidence places skeletal muscle-via its impact on insulin resistance and systemic inflammation-and the muscle-liver axis at the center of the NAFLD pathogenic cascade. Population-based studies suggest that sarcopenia is an effect-modifier across the NAFLD spectrum in that it is tightly linked to an increased risk of non-alcoholic fatty liver, non-alcoholic steatohepatitis (NASH), and advanced liver fibrosis, all independent of obesity and insulin resistance. Longitudinal studies suggest that increases in skeletal muscle mass over time may both reduce the incidence of NAFLD and improve preexisting NAFLD. Adverse muscle composition, comprising both low muscle volume and high muscle fat infiltration (myosteatosis), is highly prevalent in patients with NAFLD. The risk of functional disability conferred by low muscle volume in NAFLD is further exacerbated by the presence of myosteatosis, which is twice as common in NAFLD as in other chronic liver diseases. Crosstalk between muscle and liver is influenced by several factors, including obesity, physical inactivity, ectopic fat deposition, oxidative stress, and proinflammatory mediators. In this perspective review, we discuss key pathophysiological processes driving sarcopenia in NAFLD: anabolic resistance, insulin resistance, metabolic inflexibility and systemic inflammation. Interventions that modify muscle quantity (mass), muscle quality (fat), and physical function by simultaneously engaging multiple targets and pathways implicated in muscle-liver crosstalk may be required to address the multifactorial pathogenesis of NAFLD/NASH and provide effective and durable therapies.

Nonalcoholic fatty liver disease and sarcopenia: pathophysiological connections and therapeutic implications

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is currently one of the most common liver diseases worldwide. Recent data suggest that loss of skeletal muscle mass and function (i.e. sarcopenia) is highly prevalent and frequently overlooked in NAFLD patients. Experimental and clinical data suggest that the relationship between NAFLD and sarcopenia is pathophysiologically complex and bi-directional and there is a growing interest in unveiling how sarcopenia could influence NAFLD development and progression.

AREAS COVERED

PubMed/MEDLINE was searched for articles related to concomitant occurrence of NAFLD and sarcopenia between January 2013 and April 2020. Areas covered in this review include: (1) updated sarcopenia diagnosis strategy, (2) discussion of current data on pathophysiological connections between NAFLD and sarcopenia, and (3) analysis of current and future therapeutic implications of this knowledge.

EXPERT OPINION

Clinical studies describe a consistent association between NAFLD and sarcopenia, although a cause-effect relation remains to be determined. Active implementation of current diagnosis algorithms and optimized treatment can prevent sarcopenia related complications in subjects with NAFLD. Pathogenic pathways implicated in this relation are multiple and complex, a better understanding of them can provide novel biomarkers and targeted therapies that will hopefully have an important impact in NAFLD management.

Candidate rejuvenating factor GDF11 and tissue fibrosis: friend or foe?

Growth differentiation factor 11 (GDF11 or bone morphogenetic protein 11, BMP11) belongs to the transforming growth factor-β superfamily and is closely related to other family member-myostatin (also known as GDF8). GDF11 was firstly identified in 2004 due to its ability to rejuvenate the function of multiple organs in old mice. However, in the past few years, the heralded rejuvenating effects of GDF11 have been seriously questioned by many studies that do not support the idea that restoring levels of GDF11 in aging improves overall organ structure and function. Moreover, with increasing controversies, several other studies described the involvement of GDF11 in fibrotic processes in various organ setups. This review paper focuses on the GDF11 and its pro- or anti-fibrotic actions in major organs and tissues, with the goal to summarize our knowledge on its emerging role in regulating the progression of fibrosis in different pathological conditions, and to guide upcoming research efforts.

Serum Myostatin Predicts the Risk of Hepatocellular Carcinoma in Patients with Alcoholic Cirrhosis: A Multicenter Study

Background and Aim: Previous studies reported that serum myostatin is associated with sarcopenia. We aimed to elucidate the association between serum myostatin levels and hepatocellular carcinoma (HCC) development in patients with alcoholic liver cirrhosis (ALC). Methods: This retrospective, multicenter study assessed 1077 Asian ALC patients enrolled from 2007 to 2017. The primary endpoint was the development of HCC within 5 years. Cox proportional hazards model analyses were used to assess the association of serum myostatin levels and HCC development. The time-dependent areas under the receiver operating characteristic curve (AUROC) of serum myostatin for 5-year HCC development were calculated. Serum myostatin levels were measured using an enzyme-linked immunosorbent assay with samples collected on the index date. Results: During a median follow-up of 2.5 years, 5-year cumulative HCC incidence rates were 6.7% in the total population. The median level of serum myostatin was 3.3 ng/mL (interquartile, 2.1-5.2 ng/mL). The AUROC of serum myostatin for 5-year HCC development was 0.78 (95% confidence interval [CI], 0.76-0.81). In Cox proportional hazards model analyses, age, gender, platelet counts, and serum myostatin levels were independent risk factors for HCC development (adjusted hazard ratios [HRs] of age, male gender, platelet counts, and serum myostatin: 1.03, 2.79, 0.996, 1.18, respectively; all p < 0.05). Patients with high myostatin levels had a significantly higher risk of 5-year HCC development than those with low myostatin levels (HR 7.53, p < 0.001). Conclusion: Higher serum myostatin levels were significantly associated with a higher risk of developing HCC in ALC patients, which could identify high-risk patients who need stringent surveillance.

The association of the serum levels of myostatin, follistatin, and interleukin-6 with sarcopenia, and their impacts on survival in patients with hepatocellular carcinoma

Background/Aims

The role of serum myokine levels in sarcopenia and the outcome of hepatocellular carcinoma (HCC) patients are not clear. This study investigated the serum levels of myostatin, follistatin, and interleukin-6 (IL-6) in HCC patients and their association with sarcopenia and survival.

Methods

Using prospectively collected pretreatment samples from 238 HCC patients in a hospital from 2012 to 2015, the serum levels of 3 myokines were determined and compared to 50 samples from age and sex-matched healthy controls. Sarcopenia was evaluated using the psoas muscle index (PMI) measured at the third lumbar level in the computed tomography, and clinical data were collected until 2017.

Results

The median levels of the 3 myokines for the male and female HCC patients were as follow: myostatin (3,979.3 and 2,976.3 pg/mL), follistatin (2,118.5 and 2,174.6 pg/mL), and IL-6 (2.5 and 2.7 pg/mL), respectively. Those in the HCC patients were all significantly higher than in the healthy controls. In the HCC patient, the median PMI was 4.43 (males) and 2.17 cm²/m² (females) with a sarcopenic prevalence of 56.4%. The serum levels of myostatin, IL-6 and follistatin in the HCC patients showed a positive, negative, and no correlation with PMI, respectively. The serum follistatin level was an independent factor for poor survival in HCC patients.

Conclusions

The serum levels of myostatin, follistatin, and IL-6 and their correlation with sarcopenia and survival were presented in HCC patients for the first time. The role of the serum follistatin level as a poor prognostic biomarker warrants further study.

Profiles of advanced hepatic fibrosis evaluated by FIB-4 index and shear wave elastography in health checkup examinees

AIM

Advanced hepatic fibrosis is seen in individuals with potential hepatocellular carcinoma and cardiovascular disease. Hepatic fibrosis can be assessed using a combination of the FIB-4 index and imaging modalities, including shear wave elastography. We aimed to investigate the prevalence of advanced fibrosis in the general population and the profiles associated with advanced fibrosis using a data-mining analysis.

METHODS

We enrolled 1155 health checkup examinees (median age 53 years, 685 women, 470 male). Advanced fibrosis was defined by FIB-4 index ≥1.3 and liver stiffness ≥8.07 kPa using shear wave elastography. Participants were classified as normal-mild fibrosis (n = 1035) or advanced fibrosis (n = 120). Factors associated with advanced fibrosis were analyzed by logistic regression and decision-tree analyses.

RESULTS

Advanced fibrosis was observed in 10.4% of participants (120/1155). In the logistic regression analysis, independent factors for advanced fibrosis were age (≥75 years; OR 2.12, 95% CI 1.021-4.415; P = 0.0419) and the presence of metabolic syndrome (OR 2.51, 95% CI 1.416-4.462; P = 0.0017). The decision-tree analysis showed two profiles associated with advanced fibrosis: profile 1 - individuals aged ≥65 years with metabolic syndrome and mild-to-moderate alcohol consumption (prevalence of advanced fibrosis 73.3%); and profile 2 - individuals without metabolic syndrome, aged ≥75 years, with no exercise habit (prevalence of advanced fibrosis 56.3%).

CONCLUSIONS

Advanced fibrosis was observed in 10.4% of health checkup examinees. Furthermore, we showed that aging, metabolic syndrome with mild-to-moderate alcohol consumption, and physical inactivity were associated with advanced fibrosis. Thus, prevention of metabolic syndrome and alcohol withdrawal, as well as exercise habits, might inhibit the progression of hepatic fibrosis.