Sarcopenia associated with portosystemic shunting is reversed by follistatin

Changes in serum myostatin levels among patients with type C liver cirrhosis treated with direct-acting antivirals

AIM

To clarify whether direct-acting antiviral treatment improves serum myostatin levels of patients with cirrhosis caused by hepatitis C virus.

METHODS

A total of 99 patients with type C liver cirrhosis were administered direct-acting antiviral treatment. The median age was 73 years, and 58 patients were women. We measured the levels of serum myostatin, decorin, follistatin, and insulin-like growth factor-1, as well as the skeletal muscle mass index at baseline. We measured the sustained virological response at 48 weeks.

RESULTS

Serum myostatin levels of the Child-Pugh class B or C group (n = 30) were significantly higher than those of the Child-Pugh class A group (n = 69) at baseline. The multivariate analysis indicated that the total bilirubin level and Mac-2 binding protein glycosylation isomer level were independent factors associated with serum myostatin levels. Serum myostatin levels significantly decreased, whereas the skeletal muscle mass index and insulin-like growth factor-1 level were significantly increased at 48 weeks.

CONCLUSIONS

Direct-acting antiviral treatment decreased serum myostatin levels and may improve sarcopenia in patients with cirrhosis.

The Molecular Pathogenesis of Sarcopenia/Frailty in Cirrhosis

Cirrhosis is an important cause of morbidity and death in patients with chronic liver disease. It can be divided into compensatory and decompensated stages. During the decompensation period, complications such as esophageal and gastric varices hemorrhage, hepatic encephalopathy, infection, and hepatorenal syndrome are often incurred, which has a high mortality rate and leverages huge economic burden on society, healthcare resources, and individuals. Sarcopenia and frailty are common in patients with cirrhosis. The pathogenesis of sarcopenia and frailty in the context of cirrhosis is complicated and multifactorial, including overwhelming systemic inflammation, imbalance of muscle protein metabolism, malnutrition, endocrine and metabolic dysfunctions, intestinal microecological disorders, lack of physical exercise, and other aspects. Notably, accumulating evidence implicates that many patients experience sarcopenia/frailty even before the onset of liver cirrhosis. In this regard, the magnitude of liver fibrosis is closely linked to the progression of sarcopenia with reciprocal impact. In conclusion, this review article will shed light on the pathogenesis of cirrhosis complicated with sarcopenia/frailty, aimed at facilitating early diagnosis and effective management.

Type 2 Diabetes Mellitus Is a Risk Factor for Skeletal Muscle Loss in the Course of Dietary Treatment for Patients with Metabolic Dysfunction-associated Steatotic Liver Disease

Objective This study assessed the impact of dietary therapy and reduced body weight on the loss of skeletal muscle in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). Methods This was a single-center retrospective observational study. We enrolled 129 patients with MASLD who had undergone dietary therapy at our facility. We assessed skeletal muscle mass using a bioelectrical impedance analysis at the start of dietary treatment and 12 months after the first assessment. Variables related to muscle reduction were analyzed using a logistic regression model. Results One hundred and eighteen cases were analyzed, excluding those with missing data. In the muscle reduction group, there were more subjects with body weight reduction than in the control group (68% and 40%, respectively, p=0.002), and their body mass index (BMI) was decreased (-0.7 kg/m2 and +0.3 kg/m2, respectively, p=0.0003). There was a significant correlation between the changes in the BMI and muscle mass (R=0.48, p<0.0001). We standardized muscle mass change by dividing it by weight change to analyze the severe decrease in muscle mass compared to weight change. A logistic regression analysis revealed that type 2 diabetes mellitus (T2DM) was an independent variable related to severe skeletal muscle loss (odds ratio, 2.69; 95% CI: 1.13-6.42, p=0.03). Conclusion Weight loss is associated with skeletal muscle loss during dietary treatment for MASLD. T2DM is a risk factor for severe skeletal muscle loss.

Dynamic skeletal muscle loss and its predictive role on 90-day mortality in patients with acute-on-chronic liver failure

Background

Low skeletal muscle mass is an independent risk factor for increased mortality in patients with acute-on-chronic liver failure (ACLF). However, no study has evaluated the temporal changes in muscle mass during the course of ACLF. Therefore, this study aimed to investigate the dynamic changes in muscle mass and their prognostic role in patients with ACLF.

Methods

A retrospective analysis was conducted on consecutive patients with ACLF who underwent two or more abdominal computed tomography examinations within 90 days of admission. The percentage change rates of the skeletal muscle index at the third lumbar vertebra (L3-SMI) were calculated as (L3-SMIfinal - L3-SMIinitial)/(L3-SMIinitial) × 100%.

Results

A total of 154 patients with ACLF were included. During the course of ACLF, the percentage change rates of L3-SMI at 2-7, 8-14, 15-30, 31-60, and 61-90 days were - 0.83 ± 4.43, -3.76 ± 4.40, -7.30 ± 5.89, -10.10 ± 7.45, and - 5.53 ± 9.26, respectively. Significant reductions in L3-SMI were noted in patients with severe conditions compared to other patients at 2-7 days and 15-30 days. Moreover, the rate of decrease in L3-SMI in patients with a lower respiratory quotient (RQ) was significantly greater than that in patients with a normal RQ at 2-7 days and 15-30 days. Additionally, high muscle loss (HR 2.059; 95% CI 1.122-3.780, p = 0.020), rather than pre-existing sarcopenia (HR 1.430; 95% CI 0.724-2.826, p = 0.303) at baseline, was independently associated with 90-day mortality.

Conclusion

Deterioration in muscle mass is associated with disease severity and poor nutritional status and serves as a more effective predictor of adverse short-term outcomes in patients with ACLF. These findings underscore the importance of dynamic evaluation of muscle loss and emphasize the necessity of reversing muscle loss in patients with ACLF.

Attenuating hyperammonemia preserves protein synthesis and muscle mass via restoration of perturbed metabolic pathways in bile duct-ligated rats

Sarcopenia and hepatic encephalopathy (HE) are complications of chronic liver disease (CLD), which negatively impact clinical outcomes. Hyperammonemia is considered to be the central component in the pathogenesis of HE, however ammonia's toxic effects have also been shown to impinge on extracerebral organs including the muscle. Our aim was to investigate the effect of attenuating hyperammonemia with ornithine phenylacetate (OP) on muscle mass loss and associated molecular mechanisms in rats with CLD. Six-week bile duct-ligated (BDL) rats and Sham-operated controls were treated with OP (1 g/kg, oral) for 5 weeks. Body composition, assessed by EchoMRI, and muscle protein fractional synthesis rate were evaluated. Signalling mechanisms regulating protein homeostasis, ATP content and metabolic intermediates in the tricarboxylic acid cycle (TCA) in skeletal muscle were quantified. OP treatment attenuated hyperammonemia, prevented brain edema and improved locomotor activity in BDL rats. Increased muscle ammonia, reduction in lean body mass, decreased muscle protein synthesis rate and ATP content were restored in OP-treated versus saline-treated BDL rats. TCA cycle intermediary metabolite, α-ketoglutarate, alterations of molecular markers regulating protein homeostasis including mTOR signalling and autophagy, were also preserved in muscle of OP-treated BDL rats. OP attenuated hyperammonemia, preserved muscle protein synthesis and prevented muscle mass loss in a preclinical model of CLD through restoration of perturbed signalling responses and altered TCA intermediary metabolites. Ammonia-lowering strategies have the potential for rapid clinical translation for simultaneous neuroprotection and sarcopenia prevention in patients with CLD.

Liver-secreted FGF21 induces sarcopenia by inhibiting satellite cell myogenesis via klotho beta in decompensated cirrhosis

BACKGROUND & AIMS

Sarcopenia, a prevalent condition, significantly impacts the prognosis of patients with decompensated cirrhosis (DC). Serum fibroblast growth factor 21 (FGF21) levels are significantly higher in DC patients with sarcopenia. Satellite cells (SCs) play a role in aging- and cancer-induced sarcopenia. Here, we investigated the roles of FGF21 and SCs in DC-related sarcopenia as well as the underlying mechanisms.

METHODS

We developed two DC mouse models and performed in vivo and in vitro experiments. Klotho beta (KLB) knockout mice in SCs were constructed to investigate the role of KLB downstream of FGF21. In addition, biological samples were collected from patients with DC and control patients to validate the results.

RESULTS

Muscle wasting and impaired SC myogenesis were observed in the DC mouse model and patients with DC. Elevated circulating levels of liver-derived FGF21 were observed, which were significantly negatively correlated with skeletal muscle mass/skeletal muscle index. Liver-secreted FGF21 induces SC dysfunction, contributing to sarcopenia. Mechanistically, FGF21 in the DC state exhibits enhanced interactions with KLB on SC surfaces, leading to downstream phosphatase and tensin homolog upregulation. This inhibits the protein kinase B (PI3K/Akt) pathway, hampering SC proliferation and differentiation, and blocking new myotube formation to repair atrophy. Neutralizing circulating FGF21 using neutralizing antibodies, knockdown of hepatic FGF21 by adeno-associated virus, or knockout of KLB in SCs effectively improved or reversed DC-related sarcopenia.

CONCLUSIONS

Hepatocyte-derived FGF21 mediates liver-muscle crosstalk, which impairs muscle regeneration via the inhibition of the PI3K/Akt pathway, thereby demonstrating a novel therapeutic strategy for DC-related sarcopenia.

Ammonia transporter RhBG initiates downstream signaling and functional responses by activating NFκB

Transceptors, solute transporters that facilitate intracellular entry of molecules and also initiate intracellular signaling events, have been primarily studied in lower-order species. Ammonia, a cytotoxic endogenous metabolite, is converted to urea in hepatocytes for urinary excretion in mammals. During hyperammonemia, when hepatic metabolism is impaired, nonureagenic ammonia disposal occurs primarily in skeletal muscle. Increased ammonia uptake in skeletal muscle is mediated by a membrane-bound, 12 transmembrane domain solute transporter, Rhesus blood group-associated B glycoprotein (RhBG). We show that in addition to its transport function, RhBG interacts with myeloid differentiation primary response-88 (MyD88) to initiate an intracellular signaling cascade that culminates in activation of NFκB. We also show that ammonia-induced MyD88 signaling is independent of the canonical toll-like receptor-initiated mechanism of MyD88-dependent NFκB activation. In silico, in vitro, and in situ experiments show that the conserved cytosolic J-domain of the RhBG protein interacts with the Toll-interleukin-1 receptor (TIR) domain of MyD88. In skeletal muscle from human patients, human-induced pluripotent stem cell-derived myotubes, and myobundles show an interaction of RhBG-MyD88 during hyperammonemia. Using complementary experimental and multiomics analyses in murine myotubes and mice with muscle-specific RhBG or MyD88 deletion, we show that the RhBG-MyD88 interaction is essential for the activation of NFkB but not ammonia transport. Our studies show a paradigm of substrate-dependent regulation of transceptor function with the potential for modulation of cellular responses in mammalian systems by decoupling transport and signaling functions of transceptors.

Association of Omega-3 Polyunsaturated Fatty Acids with Sarcopenia in Liver Cirrhosis Patients with Hepatocellular Carcinoma

Background and Aims

Sarcopenia is associated with the prognosis of patients with liver cirrhosis and hepatocellular carcinoma (HCC). Given their diverse physiological activities, we hypothesized that plasma fatty acids might influence the progression of sarcopenia. This study aimed to clarify the association between fatty acids and sarcopenia in cirrhotic patients with HCC.

Methods

In this single-center retrospective study, we registered 516 cases and analyzed 414 cases of liver cirrhosis and HCC. The skeletal muscle mass index was measured using a transverse computed tomography scan image at the third lumbar vertebra. The cutoff value for sarcopenia followed the criteria set by the Japan Society of Hepatology. Fatty acid concentrations were measured by gas chromatography.

Results

Fatty acid levels, particularly omega-3 (n-3) polyunsaturated fatty acid (PUFA), were lower in patients with poor liver function (Child-Pugh grade B/C) and were negatively correlated with the albumin-bilirubin score (p<0.0001). The prognosis of HCC patients with low PUFA levels was significantly worse. Among the different fatty acid fractions, only n-3 PUFAs significantly correlated with skeletal muscle mass index (p=0.0026). In the multivariate analysis, the n-3 PUFA level was an independent variable associated with sarcopenia (p=0.0006).

Conclusions

A low level of n-3 PUFAs was associated with sarcopenia in patients with liver cirrhosis and HCC.

Pretreatment Sarcopenia and MRI-Based Radiomics to Predict the Response of Neoadjuvant Chemotherapy in Triple-Negative Breast Cancer

The association between sarcopenia and the effectiveness of neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC) remains uncertain. This study aims to examine the potential of sarcopenia as a predictive factor for the response to NAC in TNBC, and to assess whether its combination with MRI radiomic signatures can improve the predictive accuracy. We collected clinical and pathological information, as well as pretreatment breast MRI and abdominal CT images, of 121 patients with TNBC who underwent NAC at our hospital between January 2012 and September 2021. The presence of pretreatment sarcopenia was assessed using the L3 skeletal muscle index. Clinical models were constructed based on independent risk factors identified by univariate regression analysis. Radiomics data were extracted on breast MRI images and the radiomics prediction models were constructed. We integrated independent risk factors and radiomic features to build the combined models. The results of this study demonstrated that sarcopenia is an independent predictive factor for NAC efficacy in TNBC. The combination of sarcopenia and MRI radiomic signatures can further improve predictive performance.

Emerging drugs for the treatment of sarcopenia in cirrhosis of the liver

INTRODUCTION

Malnutrition and sarcopenia are common and impact the prognosis in patients with liver cirrhosis. The etiology is multifactorial and includes periods of reduced caloric intake, increased catabolism and direct molecular mechanisms that inhibit muscle synthesis. Although these conditions are widely acknowledged, and there is a growing interest in their diagnosis, robust evidence regarding the treatment and reversibility of these conditions is still lacking.

AREAS COVERED

We have explored the current evidence on the pharmacological treatment of sarcopenia in patients with cirrhosis. Additionally, we have searched for drugs already in use and ongoing trials for other chronic diseases.

EXPERT OPINION

The current guidelines recommend the use of a protein-adequate diet and moderate physical activity for treating sarcopenia in patients with cirrhosis. Currently, robust evidence is derived only from the supplementation of Branched-Chain Amino Acids, capable of increasing muscle mass and function. There are many drugs targeting various pathways that contribute to sarcopenia. However, evidence is sporadic and insufficient to suggest their use in clinical practice.Novel drugs specifically designed to enhance muscle mass and function should be developed. Finally, gender significantly influences the type of muscle alteration and therapeutic mechanisms; therefore, future studies should be designed taking gender differences into consideration.

Dexamethasone and Insulin Modulate Alanine Aminotransferase (ALT) Activity and Alanine Oxidation in C2C12 Cells in a Dose-Dependent Manner

BACKGROUND

The muscle cells myocytes are differentiated for the purpose of contraction function, which plays a major role in body metabolism and energy haemostasis, through different metabolic pathways, such as glucose and protein metabolic pathways. Alanine aminotransferase (ALT) plays a crucial role by reversibly catalysing transamination between alanine and a-ketoglutarate to form pyruvate and glutamate and by mediating the conversion of these four major intermediate metabolites. ALT plays important roles for energy homeostasis during fasting and prolonged exercise anaerobically, when muscle protein must first be broken down into its constituent amino acids.

METHODS

Mouse skeletal myoblast cell line C2C12 was cultured in Dulbecco's modified eagle medium (DMEM) growth medium, supplied with 2% horse serum supplemented with 1 uM insulin, 2 mM glutamine and penicillin and streptomycin antibiotics for seven days. The differentiation medium is refreshed every 24 hours. Then, C2C12 cells were treated with insulin and dexamethasone to examine their effects on myocytes' ALT activity.

RESULTS

In our study, we found an impact on ALT activity under different influences, including C2C12 differentiation, dexamethasone and insulin treatments, which shed light on the dynamic interplay between ALT activity, alanine metabolism, and cellular states, like differentiation and stress responses.

CONCLUSION

The study provides valuable insights into the dynamic regulation of ALT activity and alanine metabolism in C2C12 cells across differentiation and drug treatments. Further research is encouraged to explore the underlying mechanisms and their implications for muscle function, differentiation and potential therapeutic interventions in metabolic disorders.

Myostatin and the Heart

Myostatin (growth differentiation factor 8) is a member of the transforming growth factor-β superfamily. It is secreted mostly by skeletal muscles, although small amounts of myostatin are produced by the myocardium and the adipose tissue as well. Myostatin binds to activin IIB membrane receptors to activate the downstream intracellular canonical Smad2/Smad3 pathway, and additionally acts on non-Smad (non-canonical) pathways. Studies on transgenic animals have shown that overexpression of myostatin reduces the heart mass, whereas removal of myostatin has an opposite effect. In this review, we summarize the potential diagnostic and prognostic value of this protein in heart-related conditions. First, in myostatin-null mice the left ventricular internal diameters along with the diastolic and systolic volumes are larger than the respective values in wild-type mice. Myostatin is potentially secreted as part of a negative feedback loop that reduces the effects of the release of growth-promoting factors and energy reprogramming in response to hypertrophic stimuli. On the other hand, both human and animal data indicate that myostatin is involved in the development of the cardiac cachexia and heart fibrosis in the course of chronic heart failure. The understanding of the role of myostatin in such conditions might initiate a development of targeted therapies based on myostatin signaling inhibition.

Mechanisms of sarcopenia in liver cirrhosis and the role of myokines

Sarcopenia is a syndrome characterized by a decline in skeletal muscle quantity and/or quality, strength and performance, leading to unfortunate events, such as injurious falls or even death. It is not identical to frailty and malnutrition, even though there is a significant overlap among these syndromes. In patients with liver cirrhosis (LC), sarcopenia is classified as secondary and has been associated with increased morbidity and mortality during the pre- and post-transplantation period. It can be a result of malnutrition, hyperammonemia, low physical activity, endocrine abnormalities, accelerated starvation, metabolic disturbances, altered gut function leading to chronic inflammation, and alcohol abuse. Myokines are peptides mainly synthesized by contracting muscle and adipose tissue cells and may play a key role in the pathophysiology of sarcopenia. More than a hundred myokines have been recognized, but only a few have been investigated. They can be classified as negative regulators, such as myostatin, tumor growth factor-β, activins, growth differentiation factor-11, and positive regulators of muscle growth including follistatin, bone morphogenic proteins, and irisin. So far, only myostatin, follistatin, irisin and decorin have been studied in LC-associated sarcopenia. In this review, we focused on the mechanisms of cirrhosis-related sarcopenia and the role of myokines that have already been studied in the literature, either as markers helping in the diagnostic evaluation of sarcopenia, or as prognostic factors of survival. Standard therapeutic options to prevent or treat sarcopenia in LC are also being reported, as well as the possible therapeutic implication of myokines.

Liver transplantation in the patient with physical frailty

Frailty is a decline in functional reserve across multiple physiological systems. A key component of frailty is sarcopenia, which denotes a loss of skeletal muscle mass and impaired contractile function that ultimately result in physical frailty. Physical frailty/sarcopenia are frequent and contribute to adverse clinical outcomes before and after liver transplantation. Frailty indices, including the liver frailty index, focus on contractile dysfunction (physical frailty), while cross-sectional image analysis of muscle area is the most accepted and reproducible measure to define sarcopenia. Thus, physical frailty and sarcopenia are interrelated. The prevalence of physical frailty/sarcopenia is high in liver transplant candidates and these conditions have been shown to adversely impact clinical outcomes including mortality, hospitalisations, infections, and cost of care both before and after transplantation. Data on the prevalence of frailty/sarcopenia and their sex- and age-dependent impact on outcomes are not consistent in patients on the liver transplant waitlist. Physical frailty and sarcopenic obesity are frequent in the obese patient with cirrhosis, and adversely affect outcomes after liver transplantation. Nutritional interventions and physical activity remain the mainstay of management before and after transplantation, despite limited data from large scale trials. In addition to physical frailty, there is recognition that a global evaluation including a multidisciplinary approach to other components of frailty (e.g., cognition, emotional, psychosocial) also need to be addressed in patients on the transplant waitlist. Recent advances in our understanding of the underlying mechanisms of sarcopenia and contractile dysfunction have helped identify novel therapeutic targets.

Contributory roles of sarcopenia and myosteatosis in development of overt hepatic encephalopathy and mortality after transjugular intrahepatic portosystemic shunt

BACKGROUND

Skeletal muscle abnormalities, such as muscle mass depletion (sarcopenia) and fatty infiltration of the muscle (myosteatosis), are frequent complications in cirrhotic patients scheduled for transjugular intrahepatic portosystemic shunt (TIPS).

AIM

To investigate the association and predictive value of sarcopenia and myosteatosis for overt hepatic encephalopathy (HE) and mortality after TIPS.

METHODS

The records of cirrhotic patients who underwent the TIPS procedure at our hospital between January 2020 and June 2021 were retrospectively retrieved. The transversal psoas muscle thickness (TPMT) and psoas muscle attenuation (PMA) measured from the unenhanced abdominal computed tomography (CT) at the level of the third lumbar vertebrae were used to analyze the sarcopenia and myosteatosis, respectively. The area under curve (AUC) was used to evaluate the discriminative power of TPMT, PMA, and relevant clinical parameters. Fur-thermore, log-rank test was performed to compare the incidence of overt HE and survival between the different groups, and the association of risk factors with overt HE and mortality was analyzed using Cox proportional hazards regression models.

RESULTS

A total of 108 patients were collected. Among these patients, 45.4% of patients developed overt HE after TIPS treatment. Furthermore, 32.4% and 28.7% of these patients were identified to have myosteatosis and sarcopenia, respectively. Myosteatosis (51.0% vs 16.9%, P < 0.001) and sarcopenia (40.8 vs 18.6%, P = 0.011) were found to be more frequent in patients with overt HE, when compared to patients without overt HE. The receiver operating characteristics analysis indicated that the predictive power of TPMT and PMA in overt HE (AUC = 0.713 and 0.778, respectively) was higher when compared to the neutrophil lymphocyte ratio (AUC = 0.636). The cumulative incidence of overt HE was the highest in patients with concomitant sarcopenia and myosteatosis, followed by patients with myosteatosis or sarcopenia, while this was the lowest in patients without sarcopenia and myosteatosis. In addition, sarcopenia and myosteatosis were inde-pendently associated with overt HE and mortality after adjusting for confounding factors in post-TIPS patients.

CONCLUSION

CT-based estimations for sarcopenia and myosteatosis can be used as reliable predictors for the risk of developing overt HE and mortality in cirrhotic patients after TIPS.

Postprandial secretion of follistatin after gastric bypass surgery and sleeve gastrectomy

Follistatin is secreted from the liver and may regulate muscle growth and insulin sensitivity. Protein intake stimulates follistatin secretion, which may be mediated by increased glucagon in the context of low insulin concentrations. We investigated circulating follistatin after mixed-meals in two cohorts of patients who were part of previously published studies and had undergone bariatric surgery with either simultaneous assessment of amino acid absorption or administration of the GLP-1 receptor antagonist exendin-(9-39), which increased glucagon concentrations and impaired insulin secretion. Study 1 comprised obese matched subjects with previous Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) surgery and unoperated controls who underwent 6-hour mixed-meal tests with intravenous and oral tracers including intrinsically labelled caseinate in the meal. Study 2 comprised obese subjects with previous RYGB who underwent two 5-hour mixed-meal tests with concomitant exendin-(9-39) or saline infusion. In study 1, the secretion of follistatin as well as the amino acid absorption was accelerated after RYGB compared with SG and controls, but the glucagon-to-C-peptide ratios did not differ between the groups. In study 2, exendin-(9-39) administration increased postprandial glucagon concentrations and lowered insulin secretion, whereas the concentration of follistatin was unchanged. In conclusion, postprandial follistatin secretion is accelerated in patients after RYGB which might be explained by an accelerated protein absorption rate rather than the glucagon-to-insulin ratio.

Impact of Sarcopenia on Non-Alcoholic Fatty Liver Disease

With the increasing incidence of non-alcoholic fatty liver disease (NAFLD) and the aging of the population, sarcopenia is attracting attention as one of the pathological conditions involved in the development and progression of NAFLD. In NAFLD, sarcopenia is closely associated with insulin resistance and results from the atrophy of skeletal muscle, an insulin target organ. In addition, inflammatory cytokines that promote skeletal muscle protein breakdown, low adiponectin levels leading to decreased insulin sensitivity, and hyperleptinemia are also involved in NAFLD pathogenesis. The presence of sarcopenia is a prognostic factor and increases the risk of mortality in patients with cirrhosis and post-treatment liver cancer. Sarcopenia, the presence of which mainly occurs due to decreased muscle mass, combined with increased visceral fat, can lead to sarcopenia-associated obesity, which increases the risk of NASH, liver fibrosis, and cardiovascular disease. In order to treat sarcopenia, it is necessary to properly evaluate sarcopenia status. Patients with high BMI, as in sarcopenic obesity, may improve with caloric restriction. However, inadequate oral intake may lead to further loss of muscle mass. Aerobic and resistance exercise should also be used appropriately.

The effect of sarcopenia and serum myokines on prognosis and survival in cirrhotic patients: a multicenter cross-sectional study

OBJECTIVE

Sarcopenia is one of the most significant contributors to morbidity in patients with chronic liver disease. Serum myokines are potential biomarkers for detecting early sarcopenia. We aimed to investigate the relationship between serum myokines and cirrhosis-related mortality in the early stages of the disease.

METHODS

In total, 262 patients and 50 healthy controls were enrolled in this study, which was designed as a multicenter cross-sectional study. At the beginning of the study, sarcopenia was defined by computed tomography scans using the third lumbar vertebra skeletal muscle index. Serum myostatin, irisin, and follistatin levels, nutritional status of the patients, and muscle strength as measured by the handgrip test were recorded. Cirrhosis-related mortality and overall survival were evaluated in the fourth year of the study as the second checkpoint of cross-sectional analysis.

RESULTS

A total of 145 (55.3%) patients were diagnosed with sarcopenia. Multivariate analysis revealed that low BMI, high levels of myostatin, and decreased irisin levels were independent predictors of sarcopenia. While serum irisin level was the most predictive parameter in terms of 4th-year cirrhosis-related mortality in the CHILD A group, serum myostatin levels were found more indicative in the CHILD BC group regardless of sarcopenia status ( P < 0.001).

CONCLUSION

Serum myostatin levels predict sarcopenia in all stages of cirrhosis. Serum irisin levels can also be used as a potential biomarker to predict both treatable sarcopenia and cirrhosis-related mortality in CHILD A patients.

Sarcopenia in Patients with Cirrhosis after Transjugular Intrahepatic Portosystemic Shunt Placement

Background Sarcopenia is frequently found in patients with cirrhosis and is associated with liver dysfunction, cirrhosis-related complications, and poorer quality of life. Purpose To evaluate changes in skeletal muscle and fat mass at CT and to evaluate the relationship of sarcopenia to mortality in patients with cirrhosis after transjugular intrahepatic portosystemic shunt (TIPS) placement. Materials and Methods Patients who underwent TIPS between August 2016 and May 2020 were included in this retrospective study. Skeletal muscle and fat mass were evaluated at CT at the L3 vertebra at baseline and at 2 months, 5 months, and 1 year after TIPS. Sarcopenia was defined as L3 skeletal muscle index (SMI) less than 50 cm²/m² for men and less than 39 cm²/m² for women. The primary end point was change in skeletal muscle and fat mass, and secondary end points included survival and the predictive factors for survival. Changes in skeletal muscle and fat mass over time were analyzed by generalized estimating equations. Results A total of 224 patients (159 men [113 with and 46 without sarcopenia] and 65 women [32 with and 33 without sarcopenia]) were included. In male patients with sarcopenia, the mean L3 SMI increased from 41.8 cm²/m² (baseline) to 49.1 cm²/m² (at 5-month follow-up; P < .001) and 49.6 cm²/m² (at 1-year follow-up; P < .001) after TIPS. In female patients with sarcopenia, SMI increased from 33.7 cm²/m² (at baseline) to 40.6 cm²/m² (at 5-month follow-up; P < .001) and 42.0 cm²/m² (at 1-year follow-up; P < .001) after TIPS. Sarcopenia (hazard ratio, 3.0; 95% CI: 1.2, 7.8) was identified as an independent risk factor for mortality after TIPS, and the patients who converted from sarcopenic to nonsarcopenic had higher cumulative survival rate than those who did not (96.4% vs 82.1%; log-rank P = .04). Conclusion In patients with sarcopenia, both skeletal muscle and fat mass increased after transjugular intrahepatic portosystemic shunt placement. The reversal of sarcopenia could reduce the risk of death. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Lee in this issue.

Development and Validation of Prognostic Models to Estimate the Risk of Overt Hepatic Encephalopathy After TIPS Creation: A Multicenter Study

INTRODUCTION

Overt hepatic encephalopathy (HE) is a major complication of transjugular intrahepatic portosystemic shunt (TIPS). This study aimed to develop and validate prognostic models to identify patients at different risks of overt HE within 3 months after TIPS.

METHODS

Two cohorts of patients with cirrhosis undergoing TIPS insertion were retrospectively included. In the derivation cohort of 276 patients, 3 models were established in increasing order of complexity: core model (age + Child-Pugh class), sarcopenia model (core model + sarcopenia), and full model (sarcopenia model + post-TIPS portal pressure gradient). All models were internally validated for discrimination and calibration and externally validated in an independent cohort of 182 patients.

RESULTS

During a 3-month follow-up period, 61 (22.1%) and 33 patients (18.1%) developed overt HE in the derivation and validation cohort, and sarcopenia was associated with increased risk of the outcome. In the derivation cohort, the core model showed a c-statistic of 0.68 (95% confidence interval [CI] 0.61-0.75), and discrimination improved in the sarcopenia model (c-statistic 0.73; 95% CI 0.66-0.80). The full model that extended the core model with inclusion of sarcopenia and post-TIPS portal pressure gradient showed a significant improvement in discriminative ability (0.77; 95% CI 0.71-0.83; P = 0.001). Both sarcopenia and full model yielded comparable performances in the validation cohort.

DISCUSSION

We developed and externally validated 2 prediction models applied before (sarcopenia model) and after TIPS (full model) to estimate the risk of post-TIPS overt HE. These tools could aid to select appropriate candidates for TIPS and guide postoperative management.

Ammonia and the Muscle: An Emerging Point of View on Hepatic Encephalopathy

In the last years the link between the presence of muscular alterations and hepatic encephalopathy (HE), both minimal and overt, has been deeply studied. The pathophysiological background supporting the relationship between muscle depletion, and HE is characterized by an imbalance between the capacity of muscle in ammonia metabolism and trafficking and the inability of the liver in removing ammonia through urea synthesis due to liver failure and/or the presence of porto-systemic shunts. This review will focus on the clinical burden, the physio pathological mechanisms understanding the liver muscle axis and principles of management of muscular alterations in cirrhosis.

Alterations in Autophagy and Mammalian Target of Rapamycin (mTOR) Pathways Mediate Sarcopenia in Patients with Cirrhosis

Background and aims

The pathophysiology of sarcopenia in cirrhosis is poorly understood. We aimed to evaluate the histological alterations in the muscle tissue of patients with cirrhosis and sarcopenia, and identify the regulators of muscle homeostasis.

Methods

Computed tomography images at third lumbar vertebral level were used to assess skeletal muscle index (SMI) in 180 patients. Sarcopenia was diagnosed based on the SMI cut-offs from a population of similar ethnicity. Muscle biopsy was obtained from the vastus lateralis in 10 sarcopenic patients with cirrhosis, and the external oblique in five controls (voluntary kidney donors during nephrectomy). Histological changes were assessed by hematoxylin and eosin staining and immunohistochemistry for phospho-FOXO3, phospho-AKT, phospho-mTOR, and apoptosis markers (annexin V and caspase 3). The messenger ribonucleic acid (mRNA) expressions for MSTN, FoxO3, markers of ubiquitin-proteasome pathway (FBXO32, TRIM63), and markers of autophagy (Beclin-1 and LC3) were also quantified.

Results

The prevalence of sarcopenia was 14.4%. Muscle histology in sarcopenics showed atrophic angulated fibers (P = 0.002) compared to controls. Immunohistochemistry showed a significant loss of expression of phospho-mTOR (P = 0.026) and an unaltered phospho-AKT (P = 0.089) in sarcopenic patients. There were no differences in the immunostaining for annexin-V, caspase-3, and phospho-FoxO3 between the two groups. The mRNA expressions of MSTN and Beclin-1 were higher in sarcopenics (P = 0.04 and P = 0.04, respectively). The two groups did not differ in the mRNA levels for TRIM63, FBXO32, and LC3.

Conclusions

Significant muscle atrophy, increase in autophagy, MSTN gene expression, and an impaired mTOR signaling were seen in patients with sarcopenia and cirrhosis.

Evaluation of the mechanisms of sarcopenia in chronic inflammatory disease: protocol for a prospective cohort study

Background

Several chronic inflammatory diseases co-exist with and accelerate sarcopenia (reduction in muscle strength, function and mass) and negatively impact on both morbidity and mortality. There is currently limited research on the extent of sarcopenia in such conditions, how to accurately assess it and whether there are generic or disease-specific mechanisms driving sarcopenia. Therefore, this study aims to identify potential mechanisms driving sarcopenia within chronic inflammatory disease via a multi-modal approach; in an attempt to help define potential interventions for future use.

Methods

This prospective cohort study will consist of a multi-modal assessment of sarcopenia and its underlying mechanisms. Recruitment will target three chronic inflammatory diseases: chronic liver disease (CLD) (n=50), with a subset of NAFLD (n=20), inflammatory bowel disease (IBD) (n=50) and rheumatoid arthritis (RA) (n=50) both before and after therapeutic intervention. In addition, 20 age and sex matched healthy individuals will be recruited for comparison. Participants will undergo 4 assessment visits at weeks 0, 2, 12 and 24. Visits will consist of the following assessments: blood tests, anthropometrics, functional assessment, quadriceps muscle imaging, actigraphy, quality of life questionnaires, food diary collection and muscle biopsy of the vastus lateralis (at weeks 2 and 24 only). In addition, stool and urine samples will be collected for future microbiome and metabolomics analysis.

Discussion

This is the first study to use a multi-modal assessment model to phenotype sarcopenia in these chronic inflammatory diseases. We hope to identify generic as well as disease-specific mechanisms driving sarcopenia. We appreciate that these cohorts do require separate standards of care treatments which limit comparison between groups.

Ethics and dissemination

The study is approved by the Health Research Authority - West Midlands Solihull Research Ethics Service Committee Authority (REC reference: 18/WM/0167). Recruitment commenced in January 2019 and will continue until July 2021. The study was halted in March 2020 and again in January 2021 with the COVID-19 pandemic. The findings will be disseminated through peer-reviewed publications and conference presentations. All data will be stored on a secure server.

Trial registration

ClinicalTrials.gov Identifier: NCT04734496

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.

Integrated multiomics analysis identifies molecular landscape perturbations during hyperammonemia in skeletal muscle and myotubes

Ammonia is a cytotoxic molecule generated during normal cellular functions. Dysregulated ammonia metabolism, which is evident in many chronic diseases such as liver cirrhosis, heart failure, and chronic obstructive pulmonary disease, initiates a hyperammonemic stress response in tissues including skeletal muscle and in myotubes. Perturbations in levels of specific regulatory molecules have been reported, but the global responses to hyperammonemia are unclear. In this study, we used a multiomics approach to vertically integrate unbiased data generated using an assay for transposase-accessible chromatin with high-throughput sequencing, RNA-Seq, and proteomics. We then horizontally integrated these data across different models of hyperammonemia, including myotubes and mouse and human muscle tissues. Changes in chromatin accessibility and/or expression of genes resulted in distinct clusters of temporal molecular changes including transient, persistent, and delayed responses during hyperammonemia in myotubes. Known responses to hyperammonemia, including mitochondrial and oxidative dysfunction, protein homeostasis disruption, and oxidative stress pathway activation, were enriched in our datasets. During hyperammonemia, pathways that impact skeletal muscle structure and function that were consistently enriched were those that contribute to mitochondrial dysfunction, oxidative stress, and senescence. We made several novel observations, including an enrichment in antiapoptotic B-cell leukemia/lymphoma 2 family protein expression, increased calcium flux, and increased protein glycosylation in myotubes and muscle tissue upon hyperammonemia. Critical molecules in these pathways were validated experimentally. Human skeletal muscle from patients with cirrhosis displayed similar responses, establishing translational relevance. These data demonstrate complex molecular interactions during adaptive and maladaptive responses during the cellular stress response to hyperammonemia.

Multiomics-Identified Intervention to Restore Ethanol-Induced Dysregulated Proteostasis and Secondary Sarcopenia in Alcoholic Liver Disease

BACKGROUND/AIMS

Signaling and metabolic perturbations contribute to dysregulated skeletal muscle protein homeostasis and secondary sarcopenia in response to a number of cellular stressors including ethanol exposure. Using an innovative multiomics-based curating of unbiased data, we identified molecular and metabolic therapeutic targets and experimentally validated restoration of protein homeostasis in an ethanol-fed mouse model of liver disease.

METHODS

Studies were performed in ethanol-treated differentiated C2C12 myotubes and physiological relevance established in an ethanol-fed mouse model of alcohol-related liver disease (mALD) or pair-fed control C57BL/6 mice. Transcriptome and proteome from ethanol treated-myotubes and gastrocnemius muscle from mALD and pair-fed mice were analyzed to identify target pathways and molecules. Readouts including signaling responses and autophagy markers by immunoblots, mitochondrial oxidative function and free radical generation, and metabolic studies by gas chromatography-mass spectrometry and sarcopenic phenotype by imaging.

RESULTS

Multiomics analyses showed that ethanol impaired skeletal muscle mTORC1 signaling, mitochondrial oxidative pathways, including intermediary metabolite regulatory genes, interleukin-6, and amino acid degradation pathways are β-hydroxymethyl-butyrate targets. Ethanol decreased mTORC1 signaling, increased autophagy flux, impaired mitochondrial oxidative function with decreased tricarboxylic acid cycle intermediary metabolites, ATP synthesis, protein synthesis and myotube diameter that were reversed by HMB. Consistently, skeletal muscle from mALD had decreased mTORC1 signaling, reduced fractional and total muscle protein synthesis rates, increased autophagy markers, lower intermediary metabolite concentrations, and lower muscle mass and fiber diameter that were reversed by β-hydroxymethyl-butyrate treatment.

CONCLUSION

An innovative multiomics approach followed by experimental validation showed that β-hydroxymethyl-butyrate restores muscle protein homeostasis in liver disease.

Sarcopenia and frailty in decompensated cirrhosis

In patients with decompensated cirrhosis, sarcopenia and frailty are prevalent. Although several definitions exist for these terms, in the field of hepatology, sarcopenia has commonly been defined as loss of muscle mass, and frailty has been broadly defined as the phenotypic manifestation of the loss of muscle function. Prompt recognition and accurate assessment of these conditions are critical as they are both strongly associated with morbidity, mortality, poor quality of life and worse post-liver transplant outcomes in patients with cirrhosis. In this review, we describe the complex pathophysiology that underlies the clinical phenotypes of sarcopenia and frailty, their association with decompensation, and provide an overview of tools to assess these conditions in patients with cirrhosis. When available, we highlight data focusing on patients with acutely decompensated cirrhosis, such as inpatients, as this is an area of unmet clinical need. Finally, we discuss management strategies to reverse and/or prevent the development of sarcopenia and frailty, which include adequate nutritional intake of calories and protein, as well as regular exercise of at least moderate intensity, with a mix of aerobic and resistance training. Key knowledge gaps in our understanding of sarcopenia and frailty in decompensated cirrhosis remain, including best methods to measure muscle mass and function in the inpatient setting, racial/ethnic variation in the development and presentation of sarcopenia and frailty, and optimal clinical metrics to assess response to therapeutic interventions that translate into a reduction in adverse outcomes associated with these conditions.

Fatty acids suppress the steroidogenesis of the MA-10 mouse Leydig cell line by downregulating CYP11A1 and inhibiting late-stage autophagy

Obese men have lower circulating testosterone than men with an optimal body mass index. Elevated fatty acids (FAs) caused by obesity have been reported to suppress the steroidogenesis of Leydig cells. Recent studies have demonstrated that autophagy regulates steroidogenesis in endocrine cells; however, few studies have investigated the molecular mechanisms of FA-impaired steroidogenesis. To study FA regulation in the steroidogenesis of Leydig cells, MA-10 cells were treated with an FA mixture and co-treated with 8-Br-cAMP to stimulate the steroidogenesis capacity. We showed that FAs led to cellular lipid accumulation and decreased steroidogenesis of MA-10 cells, and FA-suppressed steroidogenesis was largely recovered by P5 treatment but not by 22R-OHC treatment, suggesting the primary defect was the deficiency of CYP11A1. To examine the involvement of autophagy in the steroidogenesis of Leydig cells, we treated MA-10 cells with autophagy regulators, including rapamycin, bafilomycin, and chloroquine. Inhibition of late-stage autophagy including FA-upregulated Rubicon suppressed the steroidogenesis of MA-10 cells. More interestingly, Rubicon played a novel regulatory role in the steroidogenesis of MA-10 cells, independent of inhibitors of late-stage autophagy. Collectively, this study provides novel targets to investigate the interaction between FAs and steroidogenesis in steroidogenic cells.

Statins induce skeletal muscle atrophy via GGPP depletion-dependent myostatin overexpression in skeletal muscle and brown adipose tissue

Myopathy is the major adverse effect of statins. However, the underlying mechanism of statin-induced skeletal muscle atrophy, one of statin-induced myopathy, remains to be elucidated. Myostatin is a negative regulator of skeletal muscle mass and functions. Whether myostatin is involved in statin-induced skeletal muscle atrophy remains unknown. In this study, we uncovered that simvastatin administration increased serum myostatin levels in mice. Inhibition of myostatin with follistatin, an antagonist of myostatin, improved simvastatin-induced skeletal muscle atrophy. Simvastatin induced myostatin expression not only in skeletal muscle but also in brown adipose tissue (BAT). Mechanistically, simvastatin inhibited the phosphorylation of forkhead box protein O1 (FOXO1) in C2C12 myotubes, promoting the nuclear translocation of FOXO1 and thereby stimulating the transcription of myostatin. In differentiated brown adipocytes, simvastatin promoted myostatin expression mainly by inhibiting the expression of interferon regulatory factor 4 (IRF4). Moreover, the stimulative effect of simvastatin on myostatin expression was blunted by geranylgeranyl diphosphate (GGPP) supplementation in both myotubes and brown adipocytes, suggesting that GGPP depletion was attributed to simvastatin-induced myostatin expression. Besides, the capacities of statins on stimulating myostatin expression were positively correlated with the lipophilicity of statins. Our findings provide new insights into statin-induced skeletal muscle atrophy. Graphical headlights 1. Simvastatin induces skeletal muscle atrophy via increasing serum myostatin levels in mice; 2. Simvastatin promotes myostatin expression in both skeletal muscle and brown adipose tissue through inhibiting GGPP production; 3. The stimulating effect of statins on myostatin expression is positively correlated with the lipophilicity of statins.

Follistatin secretion is enhanced by protein, but not glucose or fat ingestion, in obese persons independently of previous gastric bypass surgery

Follistatin is secreted from the liver and is involved in the regulation of muscle mass and insulin sensitivity via inhibition of activin A in humans. The secretion of follistatin seems to be stimulated by glucagon and inhibited by insulin, but only limited knowledge on the postprandial regulation of follistatin exists. Moreover, results on postoperative changes after Roux-en-Y gastric bypass (RYGB) are conflicting with reports of increased, unaltered, and lowered fasting concentrations of follistatin. In this study, we investigated postprandial follistatin and activin A concentrations after intake of isocaloric amounts of protein, fat, or glucose in subjects with obesity with and without previous RYGB to explore the regulation of follistatin by the individual macronutrients. Protein intake enhanced follistatin concentrations similarly in the two groups, whereas glucose and fat ingestion did not change postprandial follistatin concentrations. Concentrations of activin A were lower after protein intake compared with glucose intake in RYGB. Glucagon concentrations were also particularly enhanced by protein intake and tended to correlate with follistatin in RYGB. In conclusion, we demonstrated that protein intake, but not glucose or fat, is a strong stimulus for follistatin secretion in subjects with obesity and that this regulation is maintained after RYGB surgery.NEW & NOTEWORTHY Circulating follistatin and activin A were studied after intake of isocaloric protein, fat, or glucose drinks in subjects with obesity with and without previous Roux-en-Y gastric bypass (RYGB). Protein intake enhanced follistatin similarly in both groups, whereas glucose and fat ingestion did not change follistatin. Activin A was lower after protein compared with glucose in RYGB. The novel finding is that protein intake, but neither glucose nor fat, stimulates follistatin secretion independently of previous RYGB.

An Overview of the Molecular Mechanisms Contributing to Musculoskeletal Disorders in Chronic Liver Disease: Osteoporosis, Sarcopenia, and Osteoporotic Sarcopenia

The prevalence of osteoporosis and sarcopenia is significantly higher in patients with liver disease than in those without liver disease and osteoporosis and sarcopenia negatively influence morbidity and mortality in liver disease, yet these musculoskeletal disorders are frequently overlooked in clinical practice for patients with chronic liver disease. The objective of this review is to provide a comprehensive understanding of the molecular mechanisms of musculoskeletal disorders accompanying the pathogenesis of liver disease. The increased bone resorption through the receptor activator of nuclear factor kappa (RANK)-RANK ligand (RANKL)-osteoprotegerin (OPG) system and upregulation of inflammatory cytokines and decreased bone formation through increased bilirubin and sclerostin and lower insulin-like growth factor-1 are important mechanisms for osteoporosis in patients with liver disease. Sarcopenia is associated with insulin resistance and obesity in non-alcoholic fatty liver disease, whereas hyperammonemia, low amount of branched chain amino acids, and hypogonadism contributes to sarcopenia in liver cirrhosis. The bidirectional crosstalk between muscle and bone through myostatin, irisin, β-aminoisobutyric acid (BAIBA), osteocalcin, as well as the activation of the RANK and the Wnt/β-catenin pathways are associated with osteosarcopenia. The increased understandings for these musculoskeletal disorders would be contributes to the development of effective therapies targeting the pathophysiological mechanism involved.

Controlled underdilation using novel VIATORR® controlled expansion stents improves survival after transjugular intrahepatic portosystemic shunt implantation

Background & Aims

Smaller 8-mm diameter transjugular intrahepatic portosystemic shunts (TIPS) appear to be more beneficial than larger 10-mm TIPS stent-grafts, but lack the ability for secondary dilation in cases of clinical ineffectiveness. Underdilated VIATORR® TIPS stent grafts (VTS) expand passively, whereas novel VIATORR Controlled Expansion (VCX) stent grafts do not. This study evaluated the impact on survival of underdilated VCX compared with VTS in patients with decompensated cirrhosis.

Methods

This was a prospective case-control study including patients with cirrhosis receiving TIPS using 10-mm VCX underdilated to 8 mm. Patients with cirrhosis receiving 10-mm VTS underdilated to 8 mm were matched for age, sex, indication for TIPS, and liver function.

Results

A total of 114 patients (47 VCX, 47 VTS, and 20 fully dilated VCX/VTS) were included. After TIPS implantation, underdilated VCX diameter was 8.0 (7.8-9.2) mm at a median time of 359 (87-450) days, compared with VTS at 9.9 (9.7-10.0) mm (p <0.001). The portosystemic pressure gradient immediately after TIPS procedure and after 7 days did not change significantly in VCX [mean 9.4 (± 0.8) vs. 10.4 (± 0.7) mmHg, p = 0.115). Hospital readmission rates for hepatic encephalopathy were 23% (n = 11) vs 51% (n = 24) for VCX and VTS (p <0.001), respectively. Patients with VCX had significantly lower rates of large-volume paracentesis (n = 5 [11%] vs. n = 10 [21%], p = 0.017) and heart failure (n = 1 [2%] vs. n = 7 [15%], p = 0.015). One-year mortality for underdilated VCX and VTS was 15% (n = 7) and 30% (n = 14) and, for fully dilated VCX/VTS, was 45% (n = 9) (log-rank p = 0.008), respectively.

Conclusions

This study demonstrated that VCX stent grafts underdilated to 8 mm do not passively expand to nominal diameter and suggests reduced hospital readmissions because of hepatic encephalopathy, uncontrolled ascites, and heart failure, and improved 1-year survival compared with underdilated VTS.

Lay summary

Transjugular intrahepatic portosystemic shunt (TIPS) improves survival in selected patients with liver cirrhosis and acute variceal bleeding or refractory ascites. Smaller 8-mm diameter TIPS stent grafts appear to improve patient outcome compared with larger 10-mm diameter stent grafts. Novel VIATORR® Controlled Expansion (VCX) stent grafts facilitate safe and stable underdilation to 8 mm of large 10-mm diameter stent grafts with improved patient outcome (survival, hepatic encephalopathy, ascites and heart failure) compared with legacy VIATORR TIPS stent graft (VTS). Thus, the use of underdilated VCX could preserve heart function.

Clinical Trials Registration

The study is registered at Clinicaltrials.govNCT03628807.

Transcriptomic profile of semitendinosus muscle of bulls of different breed and performance

The aim of the study was to compare the transcriptomic profiles of fully differentiated skeletal muscle derived from bulls belonging to different breeds of varying performance. Microarray analyses were performed to determine the differences in the expression profiles of genes between semitendinosus muscles of 15-month-old beef-breed bulls (Limousin—LIM and Hereford—HER) and dairy-breed bulls (Holstein Friesian—HF). These analyses allowed for the identification of those genes the expression of which is similar and characteristic of fully differentiated muscle in beef breeds, but differs in skeletal muscle of a typical dairy breed. The analysis revealed 463 transcripts showing similar expression in the semitendinosus muscle of beef breeds (LIM/HER), in comparison with the dairy breed (HF). Among the identified genes, 227 were upregulated and 236 were downregulated in beef breeds. The ontological analyses revealed that the largest group of genes similarly expressed in LIM and HER was involved in the processes of protein metabolism and development of muscle organ. In beef breeds, some genes involved in protein synthesis and proteolysis showed an upregulation, including ctsd, ctsf, fhl2, fhl3, fst, sirt1, and trim63, whereas some were downregulated, including bmpr1a, bmpr2, mstn, smad2, hspa8, gsk3β, and tgfβ2. The expression of the chosen genes was confirmed by RT-qPCR technique. Thus, it can be assumed that the identified genes involved in the regulation of growth and development of muscle tissue and the processes of protein metabolism in the examined cattle breeds may be responsible for the greater gain of muscle mass in beef-breed bulls.

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.

Preclinical insights into the gut-skeletal muscle axis in chronic gastrointestinal diseases

Muscle wasting represents a constant pathological feature of common chronic gastrointestinal diseases, including liver cirrhosis (LC), inflammatory bowel diseases (IBD), chronic pancreatitis (CP) and pancreatic cancer (PC), and is associated with increased morbidity and mortality. Recent clinical and experimental studies point to the existence of a gut‐skeletal muscle axis that is constituted by specific gut‐derived mediators which activate pro‐ and anti‐sarcopenic signalling pathways in skeletal muscle cells. A pathophysiological link between both organs is also provided by low‐grade systemic inflammation. Animal models of LC, IBD, CP and PC represent an important resource for mechanistic and preclinical studies on disease‐associated muscle wasting. They are also required to test and validate specific anti‐sarcopenic therapies prior to clinical application. In this article, we review frequently used rodent models of muscle wasting in the context of chronic gastrointestinal diseases, survey their specific advantages and limitations and discuss possibilities for further research activities in the field. We conclude that animal models of LC‐, IBD‐ and PC‐associated sarcopenia are an essential supplement to clinical studies because they may provide additional mechanistic insights and help to identify molecular targets for therapeutic interventions in humans.

Exercise and physical activity in cirrhosis: opportunities or perils

Reduced exercise capacity and impaired physical performance are observed in nearly all patients with liver cirrhosis. Physical activity and exercise are physiological anabolic stimuli that can reverse dysregulated protein homeostasis or proteostasis and potentially increase muscle mass and contractile function in healthy subjects. Cirrhosis is a state of anabolic resistance, and unlike the beneficial responses to exercise reported in physiological states, there are few systematic studies evaluating the response to exercise in cirrhosis. Hyperammonemia is a mediator of the liver-muscle axis with net skeletal muscle ammonia uptake in cirrhosis causing signaling perturbations, mitochondrial dysfunction with decreased ATP content, modifications of contractile proteins, and impaired ribosomal function, all of which contribute to anabolic resistance in cirrhosis and have the potential to impair the beneficial responses to exercise. English language-publications in peer-reviewed journals that specifically evaluated the impact of exercise in cirrhosis were reviewed. Most studies evaluated responses to endurance exercise, and readouts included peak or maximum oxygen utilization, grip strength, and functional capacity. Endurance exercise for up to 12 wk is clinically tolerated in well-compensated cirrhosis. Data on the safety of resistance exercise are conflicting. Nutritional supplements enhance the benefits of exercise in healthy subjects but have not been evaluated in cirrhosis. Whether the beneficial physiological responses with endurance exercise and increase in muscle mass with resistance exercise that occur in healthy subjects also occur in cirrhotics is not known. Specific organ-system responses, changes in body composition, or improved long-term clinical outcomes with exercise in cirrhosis need evaluation.

Assessment of Malnutrition, Sarcopenia and Frailty in Patients with Cirrhosis: Which Tools Should We Use in Clinical Practice?

Malnutrition is a common comorbidity in patients with cirrhosis. Its prognostic value is indisputable as it greatly affects the evolution of liver diseases. It has a major impact on both morbi-mortality before and after liver transplantation. Being now integrated in the definition of malnutrition and recognized as a new entity in the international classification of diseases, physicians have taken great interest in sarcopenia. Its negative consequences on the fate of patients with cirrhosis are well-demonstrated. The concept of frailty has recently been enlarged to chronic liver diseases as symptoms of impaired global physical functioning. In this article, we will discuss the definitions of malnutrition and emphasize its links with sarcopenia and frailty. We will show the relevance of frailty and sarcopenia in the course of liver diseases. The emerging role of muscle depletion on the cardiorespiratory system will also be highlighted. The importance of body composition will be demonstrated and the main tools reviewed. Finally, we adapted the definition of malnutrition to patients with cirrhosis based on the assessment of sarcopenia together with reduced food intakes.

Review article: malnutrition/sarcopenia and frailty in patients with cirrhosis

BACKGROUND

Malnutrition/sarcopenia and frailty are common in patients with cirrhosis and are associated with poor outcomes.

AIM

To provide an overview of data on the importance, assessment and management of malnutrition/sarcopenia and frailty in cirrhosis.

METHODS

A literature search was conducted in PubMed and other sources, using the search terms "sarcopenia," "muscle," "malnutrition," "cirrhosis," "liver" and "frailty" from inception to April 2019, to identify the relevant studies and international guidelines.

RESULTS

The prevalence of malnutrition/sarcopenia in cirrhosis is 23%-60%. Frailty generally overlaps with malnutrition/sarcopenia in cirrhosis, leading to increased morbidity and mortality. Rapid nutritional screening assessment should be performed in all patients with cirrhosis, and more specific tests for sarcopenia should be performed in those at high risk. The pathogenesis of malnutrition/sarcopenia in cirrhosis is complex/multifactorial and not just reduction in protein/calorie intake. Hyperammonemia appears to be the main driver of sarcopenia in cirrhosis through several molecular signalling pathways. Nutritional management in malnourished patients with cirrhosis should be undertaken by a multidisciplinary team to achieve adequate protein/calorie intake. While the role of branched-chained amino acids remains somewhat contentious in achieving a global benefit of decreasing mortality- and liver-related events, they, and vitamin supplements, are recommended for those with advanced liver disease. Novel strategies to reverse sarcopenia such as hormone supplementation, long-term ammonia-lowering agents and myostatin antagonists, are currently under investigation.

CONCLUSIONS

Malnutrition/sarcopenia and frailty are unique, inter-related and multi-dimensional problems in cirrhosis which require special attention, prompt assessment and appropriate management as they significantly impact morbidity and mortality.

Atmospheric Ammonia Affects Myofiber Development and Lipid Metabolism in Growing Pig Muscle

Ammonia, an aerial pollutant in animal facilities, affects animal health. Recent studies showed that aerial ammonia negatively impacts meat quality but the mechanism remains unknown. To understand how ammonia drives its adverse effects on pig meat quality, 18 crossbred gilts were exposed to 0, 10 or 25 mg/m³ ammonia for 25 days. Ammonia exposure increased fat content in the Longissimus dorsi muscle, and meat color got lighter after 25 mg/m³ ammonia exposure. Analysis of MyHC isoforms showed an increased MyHC IIx but decreased MyHC I after ammonia exposure. Besides, muscular glutamine decreased significantly as aerial ammonia increased. Although hyperammonemia was reported to upregulate MSTN and inhibit downstream mTOR pathway, no changes have been found in the mRNA expression level of MSTN and protein expression level of mTOR signal pathway after ammonia exposure. RNA-Seq showed that 10 mg/m³ ammonia exposure altered genes related to myofiber development (MyoD1, MyoG), whereas 25 mg/m³ ammonia affected genes associated with fatty acid synthesis and β-oxidation (SCD, FADS1, FASN, ACADL). Collectively, our findings showed aerial ammonia exposure appears to regulate myofiber development and lipid metabolism in the skeletal muscle, which results in the negative impacts on meat quality in pigs.

Sarcopenia in Cirrhosis: Looking Beyond the Skeletal Muscle Loss to See the Systemic Disease

Sarcopenia is a common complication of cirrhosis and is defined as a progressive and generalized loss of skeletal muscle mass, strength, and function. Sarcopenia is associated with poor prognosis and increased mortality. How sarcopenia and muscle wasting relate to such poor outcomes requires looking beyond the overt muscle loss and at this entity as a systemic disease that affects muscles of vital organs including cardiac and respiratory muscles. This review explores the pathophysiological pathways and mechanisms that culminate in poor outcomes associated with sarcopenia. This provides a launching pad to identify potential targets for therapeutic intervention and optimization to improve patient outcomes.

Assessment and significance of sarcopenia in liver transplantation

Sarcopenia frequently occurs in cirrhotic patients who are waiting for liver transplantation (LT). This disease is associated with increased morbidity and mortality rates during the LT period. Recently, the careful assessment of nutritional status for end-stage liver disease patients has received a great deal of attention; hence, numerous methods of evaluating sarcopenia have been proposed. However, most of the methods have limitations, including a lack of objectivity, reproducibility, and ability to discriminate prognoses. In addition, many reports suggest that sarcopenia be used as an adjustment factor for the selection criteria of LT and that sarcopenia be incorporated into the selection criteria for living donor LT in our center. In this article, based on a literature review, we aim to identify the current definition of sarcopenia, the available methods of measurement, the potential novel interventions for the treatment of malnutrition and the significance of sarcopenia in LT.

Impaired Ribosomal Biogenesis by Noncanonical Degradation of β-Catenin during Hyperammonemia

Increased ribosomal biogenesis occurs during tissue hypertrophy, but whether ribosomal biogenesis is impaired during atrophy is not known. We show that hyperammonemia, which occurs in diverse chronic disorders, impairs protein synthesis as a result of decreased ribosomal content and translational capacity. Transcriptome analyses, real-time PCR, and immunoblotting showed consistent reductions in the expression of the large and small ribosomal protein subunits (RPL and RPS, respectively) in hyperammonemic murine skeletal myotubes, HEK cells, and skeletal muscle from hyperammonemic rats and human cirrhotics. Decreased ribosomal content was accompanied by decreased expression of cMYC, a positive regulator of ribosomal biogenesis, as well as reduced expression and activity of β-catenin, a transcriptional activator of cMYC. However, unlike the canonical regulation of β-catenin via glycogen synthase kinase 3β (GSK3β)-dependent degradation, GSK3β expression and phosphorylation were unaltered during hyperammonemia, and depletion of GSK3β did not prevent ammonia-induced degradation of β-catenin. Overexpression of GSK3β-resistant variants, genetic depletion of IκB kinase β (IKKβ) (activated during hyperammonemia), protein interactions, and in vitro kinase assays showed that IKKβ phosphorylated β-catenin directly. Overexpressing β-catenin restored hyperammonemia-induced perturbations in signaling responses that regulate ribosomal biogenesis. Our data show that decreased protein synthesis during hyperammonemia is mediated via a novel GSK3β-independent, IKKβ-dependent impairment of the β-catenin-cMYC axis.

Pathophysiology of hepatic encephalopathy and future treatment options

Understanding of the pathophysiology of hepatic encephalopathy has conditioned new treatment options. Ammonia detoxification in hepatic encephalopathy is regulated by two enzymes: glutaminase or glutamine synthetase. The first produces ammonia and the second detoxifies the ammonia, which is why treatments are aimed at glutaminase inhibition or glutamine synthetase activation. At present, we know that both enzymes are found not only in the liver, but also in the muscle, intestine, kidney, and brain. Therefore, current treatments can be directed at each enzyme at different sites. Awareness of those potential treatment sites makes different options of approach possible in the patient with hepatic encephalopathy, and each approach should be personalized.

Sarcopenia in cirrhosis: from pathogenesis to interventions

Sarcopenia (severe muscle depletion) is a prevalent muscle abnormality in patients with cirrhosis that confers poor prognosis both pre- and post-liver transplantation. The pathogenesis of sarcopenia is multifactorial and results from an imbalance between protein synthesis and breakdown. Nutritional, metabolic, and biochemical abnormalities seen in chronic liver disease alter whole body protein homeostasis. Hyperammonemia, increased autophagy, proteasomal activity, lower protein synthesis, and impaired mitochondrial function play an important role in muscle depletion in cirrhosis. Factors including cellular energy status, availability of metabolic substrates (e.g., branched-chain amino acids), alterations in the endocrine system (insulin resistance, circulating levels of insulin, insulin-like growth factor-1, corticosteroids, and testosterone), cytokines, myostatin, and exercise are involved in regulating muscle mass. A favored atrophy of type II fast-twitch glycolytic fibers seems to occur in patients with cirrhosis and sarcopenia. Identification of muscle biological abnormalities and underlying mechanisms is required to plan clinical trials to reverse sarcopenia through modulation of specific mechanisms. Accordingly, a combination of nutritional, physical, and pharmacological interventions might be necessary to reverse sarcopenia in cirrhosis. Moderate exercise should be combined with appropriate energy and protein intake, in accordance with clinical guidelines. Interventions with branched chain amino acids, testosterone, carnitine, or ammonia-lowering therapies should be considered individually. Various factors such as dose, type, duration of supplementations, etiology of cirrhosis, amount of dietary protein intake, and compliance with supplementation and exercise should be the focus of future large randomized controlled trials investigating both prevention and treatment of sarcopenia in this patient population.

EASL Clinical Practice Guidelines on nutrition in chronic liver disease

A frequent complication in liver cirrhosis is malnutrition, which is associated with the progression of liver failure, and with a higher rate of complications including infections, hepatic encephalopathy and ascites. In recent years, the rising prevalence of obesity has led to an increase in the number of cirrhosis cases related to non-alcoholic steatohepatitis. Malnutrition, obesity and sarcopenic obesity may worsen the prognosis of patients with liver cirrhosis and lower their survival. Nutritional monitoring and intervention is therefore crucial in chronic liver disease. These Clinical Practice Guidelines review the present knowledge in the field of nutrition in chronic liver disease and promote further research on this topic. Screening, assessment and principles of nutritional management are examined, with recommendations provided in specific settings such as hepatic encephalopathy, cirrhotic patients with bone disease, patients undergoing liver surgery or transplantation and critically ill cirrhotic patients.

Exercise in cirrhosis: Translating evidence and experience to practice

Physical inactivity, sarcopenia, and frailty are highly prevalent, independent predictors of morbidity and mortality in patients with cirrhosis. Across a range of chronic diseases, exercise training is a key recommendation supported by guidelines and, for some conditions, even by governmental funding of exercise programmes. Consistent with the broader chronic disease literature, the evidence for a benefit of exercise in cirrhosis is promising. Several small trials have reported significant improvements in muscle health (mass, strength, functional capacity), quality of life, fatigue, and reductions in the hepatic venous pressure gradient, without adverse events. With strong emerging evidence surrounding the substantial risks of sarcopenia/frailty and our first-hand experiences with liver pre-transplant exercise programmes, we contend that routine patient care in cirrhosis should include an exercise prescription. Some clinicians may lack the resources and necessary background to translate the existing evidence into a practicable intervention. Our team, comprised of physiotherapists, exercise physiologists, hepatologists, transplant specialists, and knowledge translation experts from six North American centres, has distilled the essential background information, tools, and practices into a set of information ready for immediate implementation into clinics ranging from a family practice setting to specialty cirrhosis clinics. Augmenting the rationale and evidence are supplementary materials including video and downloadable materials for both patients and the physician. Supporting the exercising patient is a section regarding information about nutrition, providing practical tips suitable for all patients with cirrhosis.

Fat-free muscle mass in magnetic resonance imaging predicts acute-on-chronic liver failure and survival in decompensated cirrhosis

Muscle mass seems to be a prognostic marker in patients with liver cirrhosis. However, reported methods to quantify muscle mass are heterogeneous, consented cutoff values are missing, and most studies have used computed tomography. This study evaluated fat-free muscle area (FFMA) as a marker of sarcopenia using magnetic resonance imaging (MRI) in patients with decompensated cirrhosis with transjugular intrahepatic portosystemic shunt (TIPS). The total erector spinae muscle area and the intramuscular fat tissue area were measured and subtracted to calculate the FFMA in 116 patients with cirrhosis by TIPS and MRI. The training cohort of 71 patients compared computed tomography-measured transversal psoas muscle thickness with FFMA. In 15 patients MRI was performed before and after TIPS, and in 12 patients follistatin serum measurements were carried out. The results on FFMA were confirmed in a validation cohort of 45 patients. FFMA correlated with follistatin and transversal psoas muscle thickness and showed slightly better association with survival than transversal psoas muscle thickness. Gender-specific cutoff values for FFMA were determined for sarcopenia. Decompensation (ascites, overt hepatic encephalopathy) persisted after TIPS in the sarcopenia group but resolved in the nonsarcopenia group. Sarcopenic patients showed no clinical improvement after TIPS as well as higher mortality, mainly due to development of acute-on-chronic liver failure. FFMA was an independent predictor of survival in these patients.

CONCLUSION

This study offers an easy-to-apply MRI-based measurement of fat-free muscle mass as a marker of sarcopenia in decompensated patients; while TIPS might improve sarcopenia and thereby survival, persistence of sarcopenia after TIPS is associated with a reduced response to TIPS and a higher risk of acute-on-chronic liver failure development and mortality. (Hepatology 2018;67:1014-1026).