Metabolic and molecular responses to leucine-enriched branched chain amino acid supplementation in the skeletal muscle of alcoholic cirrhosis

Presence of Sarcopenia and Its Rate of Change Are Independently Associated with Long-term Mortality in Patients with Liver Cirrhosis

BACKGROUND

Sarcopenia is associated with a poor prognosis in patients with liver cirrhosis. However, it is not known whether the rate of skeletal muscle depletion is also associated with a poor prognosis. We investigated the prognostic impact of the rate of skeletal muscle depletion in patients with liver cirrhosis.

METHODS

We included retrospectively all patients with liver cirrhosis who underwent both multiple computed tomography scans and hepatic venous pressure gradient (HVPG) measurements.

RESULTS

A total of 131 patients with liver cirrhosis were enrolled. The mean age of the patients was 53.7 years and alcoholic liver disease was the most common cause (61.8%). Sixty-four patients (48.9%) were diagnosed with sarcopenia. The median changes in skeletal muscle area per year (ΔSMA/y) were -0.89%. During a median follow-up period of 46.2 months (range, 3.4-87.6), 45 patients (34.4%) died. In multivariate analyses, age, Child-Pugh score, HVPG, presence of sarcopenia and ΔSMA/y were independently associated with mortality. Cumulative mortality was significantly higher in patients with ΔSMA/y < -2.4% than those with ΔSMA/y ≥ -2.4% (log-rank test, P < 0.001).

CONCLUSION

Both the presence and rate of change of sarcopenia are independently associated with long-term mortality in patients with liver cirrhosis.

Sarcopenia and chronic liver diseases

INTRODUCTION

Sarcopenia is a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength, which is commonly associated with various chronic diseases, including chronic liver diseases. Growing lines of evidence indicate that sarcopenia not only correlates with the clinical outcomes and survival of patients undergoing liver transplant, but also serves as a prognostic factor for candidates of liver transplantation and patients with hepatocellular carcinoma. Areas covered: In this review, we conducted a narrative review and search of literature from PubMed, Ovid MEDLINE, and the Cochrane Library database up to August 2018. Studies relevant to the emerging data of sarcopenia and chronic liver diseases were examined and discussed. Expert commentary: Although sarcopenia has been shown to play a vital role in the outcomes of cirrhotic patients with or without liver transplant, its impact on non-cirrhotic patients remains unclear and deserves future research efforts. To develop an effective and practical measurement of sarcopenia has become an urgent issue in the management of patients with chronic liver diseases.

ABBREVIATIONS

HCC: hepatocellular carcinoma; L3SMI: third lumbar vertebra skeletal muscle index; NAFLD: nonalcoholic fatty liver disease; VAT: visceral adipose tissue; PMA: psoas muscle area; LT: liver transplantation; AUC: area under the curve; LC: liver cirrhosis; SPPB: short physical performance battery; HU: Hounsfield units; ASM: appendicular skeletal muscle; SMI: skeletal muscle index; FLI: fatty liver index; PCLD: polycystic liver disease; DEXA: dual energy X-ray absorptiometry; BCAAs: branched-chain amino acids; BIA: bioelectrical impedance analysis; CT: computed tomography; OS: overall survival; CSA: cross-sectional area; NASH: nonalcoholic steatohepatitis; TPMT: transversal psoas muscle thickness; IMAC: intramuscular adipose tissue content; LDLT: living donor liver transplantation; PMI: psoas muscle mass index; PMTH: psoas muscle thickness by height; TPA: total psoas area; OLT: orthotopic liver transplantation; 6MWD: Six-minute walk distance; HRQOL: health-related quality of life; SMA: skeletal muscle area.

The role of Branched Chain Amino Acids in the treatment of hepatic Encephalopathy

The relationship between intake of nutrients and Hepatic Encephalopathy (HE) dates back to the historical roots of experimental hepatology. Branched-Chain Amino Acids (BCAA; Isoleucine, leucine and valine) have attracted particular interest and in 1956 Müting described the amino acid pattern in patients with cirrhosis. The abnormal plasma pattern has been characterized by the ratio between BCAA and aromatic amino acids in plasma, the so called 'Fischer´s ratio'. This ratio has been associated with the grade of HE. Under normal conditions, ammonia detoxification predominantly takes place in the liver. When the liver fails, the homeostasis is altered and muscle tissue becomes the main alternative organ for at least temporary detoxification of ammonia. BCAA are believed to support this muscle ammonia detoxification and the ammonia lowering effect of BCAA has been intensely investigated. In this review the effect of BCAA on muscle ammonia metabolism and the protein sparing and anabolic effects of BCAA are discussed. A Cochrane metaanalysis showed that BCAA had beneficial effects on HE with a number needed to treat of 5 patients (RR 0.73, 95% CI 0.61 to 0.88). The combined evidence suggests that although the pathophysiology is poorly understood, there is evidence to support clinical benefits of BCAA. BCAAs enhance muscle mass and exert anabolic effects via stimulation of protein synthesis. The beneficial long-term effects of BCAA on HE could be related to these effects and not only related to Branched-Chain Amino Acid increased ammonia metabolism.

Sarcopenic obesity in cirrhosis-The confluence of 2 prognostic titans

Sarcopenia and obesity are 2 major health conditions with a growing prevalence in cirrhosis. The concordance of these 2 conditions, sarcopenic obesity, is associated with higher rates of mortality and impact on the metabolic profile and physical function than either condition alone. To date, there is little consensus surrounding the diagnostic criteria for sarcopenia, obesity or as a result, sarcopenic obesity in patients with cirrhosis. Cross-sectional imaging, although the most accurate diagnostic technique, has practical limitations for routine use in clinical practice. Management strategies are focused on increasing muscle mass and strength. The present review provides an overview of the diagnosis, pathophysiology, prognostic implications and management strategies available for sarcopenic obesity in cirrhosis. We also discuss the associated condition myosteatosis, the pathological accumulation of fat in skeletal muscle. Much work needs to be done to advance both clinical care and research in this area. Future directions require consensus definitions for sarcopenia, obesity and sarcopenic obesity, an expansion of our understanding of the complex pathogenesis of the muscle-liver-adipose tissue axis in cirrhosis and evidence to support management recommendations for nutrition, exercise and pharmacological therapies.

Should Sarcopenia Increase Priority for Transplant or Is It a Contraindication?

PURPOSE OF REVIEW

The purpose of this review is to discuss the current evidence regarding the impact of sarcopenia on patients with cirrhosis awaiting liver transplantation and to determine if its presence should be considered a criterion for expedited transplantation or a contraindication for transplantation.

RECENT FINDINGS

Sarcopenia is a negative predictor of survival in patients on a waiting list and after liver transplant. The gut-liver axis and the liver-muscle axis have been explored to understand the complex pathophysiology of sarcopenia. Sarcopenia is a frequent finding in patients with cirrhosis. The diagnosis is ideally based on cross-sectional image analysis (CT or MRI) and treatment consists of optimization of caloric and protein intake. To date, prioritizing tools for liver transplantation have not included nutrition or sarcopenia parameters. Patients with a low Model for End-Stage Liver Disease (MELD) or MELD-Na score and sarcopenia would benefit from prioritization for transplant in order to reduce time on waiting list and therefore mortality.

Effects of branched chain amino acid supplementation on patient care outcomes in adults and children with liver cirrhosis: A systematic review

BACKGROUND & AIMS

Malnutrition is highly prevalent in chronic liver disease (CLD) due to alterations in nutrient utilization, malabsorption and poor intake. Low serum concentrations of branched chain amino acids (BCAA) in the presence of elevated aromatic acid concentrations is commonly observed in adult and children with liver cirrhosis and is associated with malnutrition and other adverse patient outcomes. The efficacy of BCAA supplementation has not been well established in adults and children with CLD. The purpose of this review was to critically evaluate the literature regarding the impact of BCAA supplementation related to changes in body composition, muscle strength, liver biomarkers, medical and hepatic complications (hepatic encephalopathy (HE), ascites, edema) and patient care outcomes (event free survival, health related quality of life, length of hospitalization).

METHODS

A total of 40 articles retrieved from PubMed or Web of Science databases (1989-2017) were included.

RESULTS

BCAA supplementation may be beneficial in improving muscle strength, ascites and edema with potential clinically significant improvements in HE in adult liver patients. In children, limited data have shown that BCAA supplementation may exert favourable effects on weight, fat mass, fat free mass and serum albumin level.

CONCLUSIONS

Heterogeneity of study findings attributed to variability in BCAA dose (total, relative proportions), duration, disease severity and lack of uniformity in tools used for assessing patient outcomes limit overall conclusions. Longitudinal studies examining the efficacy of BCAA supplementation as a therapeutic treatment of malnutrition in chronic liver disease is warranted.

Rapidly declining skeletal muscle mass predicts poor prognosis of hepatocellular carcinoma treated with transcatheter intra-arterial therapies

Background

The impact of sarcopenia on the prognosis of patients with hepatocellular carcinoma (HCC) who receive transcatheter intra-arterial therapies, including transcatheter arterial chemoembolization and transcatheter arterial infusion chemotherapy, remains unclear. We investigated the prognostic value of skeletal muscle loss (SML) stratified by cutoffs for sarcopenia and rate of change in skeletal muscle mass over 6 months.

Methods

We retrospectively evaluated 102 patients with HCC treated with transcatheter intra-arterial therapies between 2005 and 2015. Computed tomography images of the third lumbar vertebra (L3) were analyzed to obtain the skeletal muscle area normalized for the height squared, defined as the skeletal muscle index at L3 (L3 SMI), before and 6 months after treatment. Low or high SMI was defined using cutoff values of 42 cm²/m² in men and 38 cm²/m² in women. The rate of change in skeletal muscle mass (ΔL3 SMI) over 6 months was calculated. Overall survival (OS) was compared in groups classified by baseline L3 SMI and ΔL3 SMI; prognostic significance was assessed with univariate and multivariate analyses, using Cox proportional hazards models.

Results

OS did not differ significantly between groups with low (n = 31) and high (n = 71) SMI at baseline (P = 0.172), but OS was significantly poorer in patients with SML (n = 41), defined as ΔL3 SMI < − 4.6% over 6 months than in those without SML (n = 61, P = 0.018). On multivariate analysis, SML (hazard ratio [HR], 1.675; 95% confidence interval [CI], 1.031–2.721; P = 0.037), serum alpha-fetoprotein ≥20 ng/mL (HR, 2.550; 95% CI, 1.440–4.515; P = 0.001), and maximum tumor diameter ≥ 30 mm (HR, 1.925; 95% CI, 1.166–3.179; P = 0.010) were independent predictors of poor OS. Baseline L3 SMI was not significantly associated with OS (HR, 1.405; 95% CI, 0.861–2.293; P = 0.174).

Conclusions

ΔL3 SMI was an independent prognostic factor in patients with HCC treated with transcatheter intra-arterial therapies. Further study is required to reveal whether prevention of skeletal muscle depletion might be a new therapeutic strategy to contribute to improved clinical outcomes in patients with HCC.

Update on the Therapeutic Management of Hepatic Encephalopathy

PURPOSE OF REVIEW

Hepatic encephalopathy (HE) is a common and devastating complication to chronic liver disease. In this paper, we summarize the latest research and evidence of both conventional and up-coming treatments.

RECENT FINDINGS

Meta-analyses report beneficial effects of lactulose, branched-chain amino acids, rifaximin, and to some degree L-ornithine L-aspartate on the manifestations of HE in patients with cirrhosis, and generally the numbers needed to treat are low. Recent studies on newer HE treatments including ornithine phenylacetate, spherical carbon, and fecal microbiota transplant also report potentially beneficial effects on HE manifestations. The conventional treatments benefit patients with HE. Newer treatments are under study and more research is needed for their validation.

Branched-chain amino acids in liver diseases

Branched chain amino acids (BCAAs) are involved in various bioprocess such as protein metabolism, gene expression, insulin resistance and proliferation of hepatocytes. BCAAs have also been reported to suppress the growth of hepatocellular carcinoma (HCC) cells in vitro and to be required for immune cells to perform the function. In advanced cirrhotic patients, it has been clarified that serum concentrations of BCAA are decreased, whereas those of aromatic amino acids (AAAs) are increased. These alterations are thought to be the causes of hepatic encephalopathy (HE), sarcopenia and hepatocarcinogenesis and may be associated with the poor prognosis of patients with these conditions. Administration of BCAA-rich medicines has shown positive results in patients with cirrhosis.

Hyperammonemia and proteostasis in cirrhosis

PURPOSE OF REVIEW

Skeletal muscle loss or sarcopenia is a frequent complication of cirrhosis that adversely affects clinical outcomes. As skeletal muscle is the largest store of proteins in the body, proteostasis or protein homeostasis is required for maintenance of muscle mass. This review will focus on disordered skeletal muscle proteostasis in liver disease.

RECENT FINDINGS

Increased skeletal muscle uptake of ammonia initiates responses that result in disordered proteostasis including impaired protein synthesis and increased autophagy. The cellular response to the stress of hyperammonemia (hyperammonemic stress response, HASR) involves the coordinated action of diverse signaling pathways targeting the molecular mechanisms of regulation of protein synthesis. Transcriptional upregulation of myostatin, a TGFβ superfamily member, results in impaired mTORC1 signaling. Phosphorylation of the eukaryotic translation initiation factor 2α (eIF2α) also relates to decreased global protein synthesis rates and mTORC1 signaling. Ammonia also causes mitochondrial and bioenergetic dysfunction because of cataplerosis of α-ketoglutarate. Lowering ammonia, targeting components of HASR and regulating cellular amino acid levels can potentially restore proteostasis.

SUMMARY

Signaling via myostatin and eIF2α phosphorylation causes decreases in protein synthesis and mTORC1 activity with a parallel mitochondrial dysfunction and increased autophagy contributing to proteostasis perturbations during skeletal muscle hyperammonemia of liver disease.

Sarcopenia in Liver Disease: Current Evidence and Issues to Be sResolved

Sarcopenia is a common clinical symptom in aging and patients with wasting diseases, characterized by a decreased skeletal muscle mass. As a consequence of lifestyle change, the nonalcoholic fatty liver disease (NAFLD) presents a rising trend. In the past three decades, increasing evidence has proved that sarcopenia is related to NAFLD. In this chapter, we will summarize the emerging evidence of the predictive role of sarcopenia in NAFLD and review the diagnosis value, feasible mechanism, and therapy strategies of sarcopenia in NAFLD. Sarcopenia is a potential risk factor for NAFLD, and targeting sarcopenia can benefit NAFLD to some extent.

Sarcopenia predicts minimal hepatic encephalopathy in patients with liver cirrhosis

AIM

Minimal hepatic encephalopathy (MHE) and sarcopenia impair the health-related quality of life and prognosis of patients with liver cirrhosis; however, the relationship between MHE and sarcopenia remains unclear. The aim of this study was to investigate their relationship and to identify the predictors of MHE in cirrhotic patients.

METHODS

This retrospective study evaluated 120 cirrhotic patients who were tested for MHE and sarcopenia. Minimal hepatic encephalopathy was diagnosed by using the computer-aided neuropsychiatric test. Sarcopenia was diagnosed based on the assessment criteria recommended by the Japan Society of Hepatology. Muscle mass and muscle strength were measured by using bio-impedance analysis and digital grip strength dynamometer. Univariate and multivariate logistic regression analyses were carried out to identify the predictors of MHE.

RESULTS

Of the 120 cirrhotic patients, 28 (23%) and 32 (27%) were diagnosed with MHE and sarcopenia, respectively. The prevalence of MHE was higher in patients with sarcopenia than in those without sarcopenia (P = 0.01). By the univariate analysis, MHE was significantly complicated with sarcopenia (P < 0.01). In the multivariate analysis, sarcopenia (odds ratio = 3.31, 95% confidence interval = 1.19-9.42; P = 0.02) and serum branched-chain amino acids levels <327 nmol/mL (odds ratio = 2.98, 95% confidence interval = 1.08-8.34; P = 0.03) were found to be associated with MHE.

CONCLUSIONS

Sarcopenia and serum branched-chain amino acids levels were predictors of MHE. The amelioration of sarcopenia and/or amino acids imbalance may improve MHE in patients with liver cirrhosis.

Nutrition and Muscle in Cirrhosis

As the cirrhosis progresses, development of complication like ascites, hepatic encephalopathy, variceal bleeding, kidney dysfunction, and hepatocellular carcinoma signify increasing risk of short term mortality. Malnutrition and muscle wasting (sarcopenia) is yet other complications that negatively impact survival, quality of life, and response to stressors, such as infection and surgery in patients with cirrhosis. Conventionally, these are not routinely looked for, because nutritional assessment can be a difficult especially if there is associated fluid retention and/or obesity. Patients with cirrhosis may have a combination of loss of skeletal muscle and gain of adipose tissue, culminating in the condition of "sarcopenic obesity." Sarcopenia in cirrhotic patients has been associated with increased mortality, sepsis complications, hyperammonemia, overt hepatic encephalopathy, and increased length of stay after liver transplantation. Assessment of muscles with cross-sectional imaging studies has become an attractive index of nutritional status evaluation in cirrhosis, as sarcopenia, the major component of malnutrition, is primarily responsible for the adverse clinical consequences seen in patients with liver disease. Cirrhosis is a state of accelerated starvation, with increased gluconeogenesis that requires amino acid diversion from other metabolic functions. Protein homeostasis is disturbed in cirrhosis due to several factors such as hyperammonemia, hormonal, and cytokine abnormalities, physical inactivity and direct effects of ethanol and its metabolites. New approaches to manage sarcopenia are being evolved. Branched chain amino acid supplementation, Myostatin inhibitors, and mitochondrial protective agents are currently in various stages of evaluation in preclinical studies to prevent and reverse sarcopenia, in cirrhosis.

The impact of nutrition on quality of life of patients with hepatitis C

PURPOSE OF REVIEW

The aim of this study was to review the most recent aspects of nutrition and its impact on health-related quality of life (HRQOL) in patients with chronic hepatitis C (CHC).

RECENT FINDINGS

Low HRQOL scores have been found in all stages of hepatitis C virus (HCV) infection. Of the factors linked to HRQOL, three aspects should be emphasized, nutritional status, physical activity and mental health status. Regarding the nutrition and metabolic conditions, a broad spectrum of nutritional disorders may impact on HRQOL of patients with CHC.

SUMMARY

Malnutrition, which is a significant comorbidity in end-stage of all chronic liver diseases, has been recognized as a significant factor related to poor HRQOL. Of note, in individuals chronically infected with HCV, low muscle skeletal mass, an early indicator of undernourishment, precedes the development of cirrhosis. Because of the strict linkage between HRQOL, nutrition and physical activity, the assessment of the musculoskeletal system abnormalities in every patient with CHC, independently of the stage of the liver disease, is of utmost relevance. Maintenance of healthy skeletal muscle is essential to reduce the negative effects of sarcopenia on HRQOL. Otherwise, overweight/obesity and chronic HCV infection can cause insulin resistance, which has been associated with HRQOL impairment.

Sarcopenia in Alcoholic Liver Disease: Clinical and Molecular Advances

Despite advances in treatment of alcohol use disorders that focus on increasing abstinence and reducing recidivism, alcoholic liver disease (ALD) is projected to be the major cause of cirrhosis and its complications. Malnutrition is recognized as the most frequent complication in ALD, and despite the high clinical significance, there are no effective therapies to reverse malnutrition in ALD. Malnutrition is a relatively imprecise term, and sarcopenia or skeletal muscle loss, the major component of malnutrition, is primarily responsible for the adverse clinical consequences in patients with liver disease. It is, therefore, critical to define the specific abnormality (sarcopenia) rather than malnutrition in ALD, so that therapies targeting sarcopenia can be developed. Skeletal muscle mass is maintained by a balance between protein synthesis and proteolysis. Both direct effects of ethanol (EtOH) and its metabolites on the skeletal muscle and the consequences of liver disease result in disturbed proteostasis (protein homeostasis) and consequent sarcopenia. Once cirrhosis develops in patients with ALD, abstinence is unlikely to be effective in completely reversing sarcopenia, as other contributors including hyperammonemia, hormonal, and cytokine abnormalities aggravate sarcopenia and maintain a state of anabolic resistance initiated by EtOH. Cirrhosis is also a state of accelerated starvation, with increased gluconeogenesis that requires amino acid diversion from signaling and substrate functions. Novel therapeutic options are being recognized that are likely to supplant the current "deficiency replacement" approach and instead focus on specific molecular perturbations, given the increasing availability of small molecules that can target specific signaling components. Myostatin antagonists, leucine supplementation, and mitochondrial protective agents are currently in various stages of evaluation in preclinical studies to prevent and reverse sarcopenia, in cirrhosis in general, and ALD, specifically. Translation of these data to human studies and clinical application requires priority for allocation of resources.

Ammonia lowering reverses sarcopenia of cirrhosis by restoring skeletal muscle proteostasis

Sarcopenia or skeletal muscle loss is a frequent, potentially reversible complication in cirrhosis that adversely affects clinical outcomes. Hyperammonemia is a consistent abnormality in cirrhosis that results in impaired skeletal muscle protein synthesis and breakdown (proteostasis). Despite the availability of effective ammonia-lowering therapies, whether lowering ammonia restores proteostasis and increases muscle mass is unknown. Myotube diameter, protein synthesis, and molecular responses in C2C12 murine myotubes to withdrawal of ammonium acetate following 24-hour exposure to 10 mM ammonium acetate were complemented by in vivo studies in the hyperammonemic portacaval anastomosis rat and sham-operated, pair-fed Sprague-Dawley rats treated with ammonia-lowering therapy by l-ornithine l-aspartate and rifaximin orally for 4 weeks. We observed reduced myotube diameter, impaired protein synthesis, and increased autophagy flux in response to hyperammonemia, which were partially reversed following 24-hour and 48-hour withdrawal of ammonium acetate. Consistently, 4 weeks of ammonia-lowering therapy resulted in significant lowering of blood and skeletal muscle ammonia, increase in lean body mass, improved grip strength, higher skeletal muscle mass and diameter, and an increase in type 2 fibers in treated compared to untreated portacaval anastomosis rats. The increased skeletal muscle myostatin expression, reduced mammalian target of rapamycin complex 1 function, and hyperammonemic stress response including autophagy markers normally found in portacaval anastomosis rats were reversed by treatment with ammonia-lowering therapy. Despite significant improvement, molecular and functional readouts were not completely reversed by ammonia-lowering measures.

CONCLUSION

Ammonia-lowering therapy results in improvement in skeletal muscle phenotype and function and molecular perturbations of hyperammonemia; these preclinical studies complement previous studies on ammonia-induced skeletal muscle loss and lay the foundation for prolonged ammonia-lowering therapy to reverse sarcopenia of cirrhosis. (Hepatology 2017;65:2045-2058).

Branched-chain amino acid supplementation in treatment of liver cirrhosis: Updated views on how to attenuate their harmful effects on cataplerosis and ammonia formation

Branched-chain amino acid (BCAA; valine, leucine, and isoleucine) supplementation is common for patients with liver cirrhosis due to decreased levels of BCAA in the blood plasma of these patients, which plays a role in pathogenesis of hepatic encephalopathy and cachexia. The unique pharmacologic properties of BCAA also are a factor for use as supplementation in this population. In the present article, BCAA is shown to provide nitrogen to alpha-ketoglutarate (α-KG) for synthesis of glutamate, which is a substrate for ammonia detoxification to glutamine (GLN) in the brain and muscles. The article also demonstrates that the favorable effects of BCAA supplementation might be associated with three adverse effects: draining of α-KG from tricarboxylic acid cycle (cataplerosis), increased GLN content and altered glutamatergic neurotransmission in the brain, and activated GLN catabolism to ammonia in the gut and kidneys. Cataplerosis of α-KG can be attenuated by dimethyl-α-ketoglutarate, l-ornithine-l-aspartate, and ornithine salt of α-KG. The pros and cons of GLN elimination from the body using phenylbutyrate (phenylacetate), which may impair liver regeneration and decrease BCAA levels, should be examined. The therapeutic potential of BCAA might be enhanced also by optimizing its supplementation protocol. It is concluded that the search for strategies attenuating adverse and increasing positive effects of the BCAA is needed to include the BCAA among standard medications for patients with cirrhosis of the liver.

Ammonia toxicity: from head to toe?

Ammonia is diffused and transported across all plasma membranes. This entails that hyperammonemia leads to an increase in ammonia in all organs and tissues. It is known that the toxic ramifications of ammonia primarily touch the brain and cause neurological impairment. However, the deleterious effects of ammonia are not specific to the brain, as the direct effect of increased ammonia (change in pH, membrane potential, metabolism) can occur in any type of cell. Therefore, in the setting of chronic liver disease where multi-organ dysfunction is common, the role of ammonia, only as neurotoxin, is challenged. This review provides insights and evidence that increased ammonia can disturb many organ and cell types and hence lead to dysfunction.

Effects of in-hospital exercise on liver function, physical ability, and muscle mass during treatment of hepatoma in patients with chronic liver disease

AIMS

Sarcopenia and physical disability assessed by a 6-min walking test (6MWT) are associated with poor prognosis of patients with chronic liver disease (CLD). However, CLD patients with hepatocellular carcinoma (HCC) mostly rest in bed during hospitalization. We aimed to investigate the effects of therapeutic exercise on liver function, 6MWT, and skeletal muscle mass during HCC treatment in patients with CLD.

METHODS

We enrolled 54 CLD patients with HCC (median age, 76 years). During hospitalization, patients performed a combination of stretching, strength training, balance practice, and endurance training (2.5-4 metabolic equivalents/20 min/day). Primary outcomes were changes from admission to discharge in Child-Pugh class, 6MWT, and skeletal muscle mass. Furthermore, factors associated with skeletal muscle atrophy were analyzed by a decision-tree analysis.

RESULTS

Exercise did not worsen the Child-Pugh class. On discharge, the 6MWT ambulation distance was maintained, and heart rate variability during the 6MWT was significantly improved compared to that on admission (area under the curve 50.3 vs. 39.0 arbitrary units; P = 0.0027). Although skeletal muscle mass was significantly reduced (20.6 kg vs. 20.0 kg, P = 0.0301), branched-chain amino acid (BCAA) treatment was identified as the most distinguishable factor for minimizing muscle mass atrophy (-1.1 kg vs. -0.5 kg/hospitalization).

CONCLUSIONS

Therapeutic exercise improved physical ability without worsening liver function during hospitalization for HCC treatment in CLD patients. Although exercise did not completely prevent skeletal muscle atrophy, BCAA treatment minimized the skeletal muscle atrophy. Thus, exercise with BCAA treatment may be important for the management of CLD patients with HCC.

Protein Intake, Especially Vegetable Protein Intake, Is Associated with Higher Skeletal Muscle Mass in Elderly Patients with Type 2 Diabetes

BACKGROUND/AIMS

Protein intake is important for maintaining muscle mass in general population. However, it remains to be elucidated the association between dietary protein intake and skeletal muscle mass in elderly patients with type 2 diabetes.

METHODS

In this cross-sectional study of 168 elderly patients with type 2 diabetes, we investigated the relationship between skeletal muscle index (SMI) and protein intake. Bioimpedance analysis was used for measurement for skeletal muscle mass (kg) and SMI (%), which was defined as skeletal muscle mass (kg)/total body weight (kg) × 100. Habitual food and nutrient intake were estimated by a questionnaire.

RESULTS

Protein intake was independently correlated with SMI after adjusting for age, hemoglobin A1c, C-peptide index, exercise, smoking, insulin treatment, total energy intake, and C-reactive protein (standardized regression coefficient = 0.664, P < 0.001 in men and standardized regression coefficient = 0.516, P = 0.005 in women). Additionally, the animal protein to vegetable protein ratio was negatively correlated with SMI after adjusting for covariates in men (standardized regression coefficient = -0.339, P = 0.005).

CONCLUSIONS

We found that total protein intake, especially vegetable protein intake, was positively associated with skeletal muscle mass in elderly patients with type 2 diabetes.

What is new about diet in hepatic encephalopathy

There is a relationship between hepatic encephalopathy (HE) protein malnutrition and muscle wasting. Muscle may play an alternative role in ammonia detoxification. Molecular mechanisms responsible for muscle depletion are under investigation. Specific nutrients may interact to reverse the molecular pathways involved in muscle wasting at an early stage. Training exercises have also been proposed to improve skeletal muscle mass. However, these data refer to small groups of patients. The amelioration of muscle mass may potentially help to prevent HE. The pathogenesis of HE is associated with modifications of the gut microbiota and diet is emerging to play a relevant role in the modulation of the gut milieu. Vegetarian and fibre-rich diets have been shown to induce beneficial changes on gut microbiota in healthy people, with reduction of Bacteroides spp., Enterobacteriaceae, and Clostridium cluster XIVa bacteria. By way of contrast, it has been suggested that a high-fat or protein diet may increase Firmicutes and reduce Bacteroidetes phylum. Milk-lysozyme and milk-oligosaccharides have also been proposed to induce a "healthy" microbiota. At present, no studies have been published describing the modification of the gut microbiota in cirrhotic patients with HE as a response to specific diets. New research is needed to evaluate the potentiality of foods in the modulation of gut microbiota in liver disease and HE.

Sarcopenia from mechanism to diagnosis and treatment in liver disease

Sarcopenia or loss of skeletal muscle mass is the major component of malnutrition and is a frequent complication in cirrhosis that adversely affects clinical outcomes. These include survival, quality of life, development of other complications and post liver transplantation survival. Radiological image analysis is currently utilized to diagnose sarcopenia in cirrhosis. Nutrient supplementation and physical activity are used to counter sarcopenia but have not been consistently effective because the underlying molecular and metabolic abnormalities persist or are not influenced by these treatments. Even though alterations in food intake, hypermetabolism, alterations in amino acid profiles, endotoxemia, accelerated starvation and decreased mobility may all contribute to sarcopenia in cirrhosis, hyperammonemia has recently gained attention as a possible mediator of the liver-muscle axis. Increased muscle ammonia causes: cataplerosis of α-ketoglutarate, increased transport of leucine in exchange for glutamine, impaired signaling by leucine, increased expression of myostatin (a transforming growth factor beta superfamily member) and an increased phosphorylation of eukaryotic initiation factor 2α. In addition, mitochondrial dysfunction, increased reactive oxygen species that decrease protein synthesis and increased autophagy mediated proteolysis, also play a role. These molecular and metabolic alterations may contribute to the anabolic resistance and inadequate response to nutrient supplementation in cirrhosis. Central and skeletal muscle fatigue contributes to impaired exercise capacity and responses. Use of proteins with low ammoniagenic potential, leucine enriched amino acid supplementation, long-term ammonia lowering strategies and a combination of resistance and endurance exercise to increase muscle mass and function may target the molecular abnormalities in the muscle. Strategies targeting endotoxemia and the gut microbiome need further evaluation.

New technologies - new insights into the pathogenesis of hepatic encephalopathy

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome which frequently accompanies acute or chronic liver disease. It is characterized by a variety of symptoms of different severity such as cognitive deficits and impaired motor functions. Currently, HE is seen as a consequence of a low grade cerebral oedema associated with the formation of cerebral oxidative stress and deranged cerebral oscillatory networks. However, the pathogenesis of HE is still incompletely understood as liver dysfunction triggers exceptionally complex metabolic derangements in the body which need to be investigated by appropriate technologies. This review summarizes technological approaches presented at the ISHEN conference 2014 in London which may help to gain new insights into the pathogenesis of HE. Dynamic in vivo ¹³C nuclear magnetic resonance spectroscopy was performed to analyse effects of chronic liver failure in rats on brain energy metabolism. By using a genomics approach, microRNA expression changes were identified in plasma of animals with acute liver failure which may be involved in interorgan interactions and which may serve as organ-specific biomarkers for tissue damage during acute liver failure. Genomics were also applied to analyse glutaminase gene polymorphisms in patients with liver cirrhosis indicating that haplotype-dependent glutaminase activity is an important pathogenic factor in HE. Metabonomics represents a promising approach to better understand HE, by capturing the systems level metabolic changes associated with disease in individuals, and enabling monitoring of metabolic phenotypes in real time, over a time course and in response to treatment, to better inform clinical decision making. Targeted fluxomics allow the determination of metabolic reaction rates thereby discriminating metabolite level changes in HE in terms of production, consumption and clearance.

Metabolic adaptation of skeletal muscle to hyperammonemia drives the beneficial effects of l-leucine in cirrhosis

BACKGROUND & AIMS

Increased skeletal muscle ammonia uptake with loss of muscle mass adversely affects clinical outcomes in cirrhosis. Hyperammonemia causes reduced protein synthesis and sarcopenia but the cellular responses to impaired proteostasis and molecular mechanism of l-leucine induced adaptation to ammonia induced stress were determined.

METHODS

Response to activation of amino acid deficiency sensor, GCN2, in the skeletal muscle from cirrhotic patients and the portacaval anastomosis (PCA) rat were quantified. During hyperammonemia and l-leucine supplementation, protein synthesis, phosphorylation of eIF2α, mTORC1 signaling, l-leucine transport and response to l-leucine supplementation were quantified. Adaptation to cellular stress via ATF4 and its target GADD34 were also determined.

RESULTS

Activation of the eIF2α kinase GCN2 and impaired mTORC1 signaling were observed in skeletal muscle from cirrhotic patients and PCA rats. Ammonia activated GCN2 mediated eIF2α phosphorylation (eIF2α-P) and impaired mTORC1 signaling that inhibit protein synthesis in myotubes and MEFs. Adaptation to ammonia induced stress did not involve translational reprogramming by activation transcription factor 4 (ATF4) dependent induction of the eIF2α-P phosphatase subunit GADD34. Instead, ammonia increased expression of the leucine/glutamine exchanger SLC7A5, l-leucine uptake and intracellular l-leucine levels, the latter not being sufficient to rescue the inhibition of protein synthesis, due to potentially enhanced mitochondrial sequestration of l-leucine. l-leucine supplementation rescued protein synthesis inhibition caused by hyperammonemia.

CONCLUSIONS

Response to hyperammonemia is reminiscent of the cellular response to amino acid starvation, but lacks the adaptive ATF4 dependent integrated stress response (ISR). Instead, hyperammonemia-induced l-leucine uptake was an adaptive response to the GCN2-mediated decreased protein synthesis.

LAY SUMMARY

Sarcopenia or skeletal muscle loss is the most frequent complication in cirrhosis but there are no treatments because the cause(s) of muscle loss in liver disease are not known. Results from laboratory experiments in animals and muscle cells were validated in human patients with cirrhosis to show that ammonia plays a key role in causing muscle loss in patients with cirrhosis. We identified a novel stress response to ammonia in the muscle that decreases muscle protein content that can be reversed by supplementation with the amino acid l-leucine.

Testosterone therapy increases muscle mass in men with cirrhosis and low testosterone: A randomised controlled trial

BACKGROUND & AIMS

Low testosterone and sarcopenia are common in men with cirrhosis and both are associated with increased mortality. Whether testosterone therapy in cirrhosis improves muscle mass and other outcomes is unknown.

METHODS

We conducted a 12-month, double-blinded, placebo-controlled trial of intramuscular testosterone undecanoate in 101 men with established cirrhosis and low serum testosterone (total testosterone <12nmol/L or free testosterone <230pmol/L) in a single tertiary centre. Body composition was assessed using dual-energy X-ray absorptiometry at baseline, 6 and 12months.

RESULTS

At study completion, appendicular lean mass was significant higher in testosterone-treated subjects, with a mean adjusted difference (MAD) of +1.69kg, (CI +0.40; +2.97kg, p=0.021). Secondary outcomes included a substantially higher total lean mass in the active group (MAD +4.74kg, CI +1.75; +7.74kg, p=0.008), matched by reduced fat mass (MAD -4.34kg, CI -6.65; -2.04, p<0.001). Total bone mass increased (MAD +0.08kg, CI +0.01; +0.15kg, p=0.009) as did bone mineral density at the femoral neck (MAD +0.287points, CI +0.140; +0.434, p<0.001). Haemoglobin was higher with testosterone therapy (MAD +10.2g/L, CI +1.50; +18.9g/L, p=0.041) and percentage glycosylated haemoglobin (HbA1c) lower (MAD -0.35%, CI -0.05; -0.54, p=0.028). Mortality was non-significantly lower in testosterone-treated patients (16% vs. 25.5%, p=0.352). There was no increase in adverse events in testosterone-treated subjects.

CONCLUSION

Testosterone therapy in men with cirrhosis and low serum testosterone safely increases muscle mass, bone mass and haemoglobin, and reduces fat mass and HbA1c. This is the first evidence-based therapy for sarcopenia in cirrhosis and thus requires larger-scale investigation into its potential impact on mortality.

LAY SUMMARY

Both low testosterone and muscle wasting are associated with increased risk of death in men with severe liver disease. Administering testosterone to men with liver disease who have low testosterone levels significantly increases their muscle mass. In addition, testosterone has non-muscle beneficial effects which may be able to increase survival in this population.

CLINICAL TRIAL NUMBER

Australian New Zealand Clinical Trials Registry trial number ACTRN 12614000526673.

BCKA down-regulates mTORC2-Akt signal and enhances apoptosis susceptibility in cardiomyocytes

Diabetic mellitus (DM) portends poor prognosis concerning pressure overloaded heart disease. Branched-chain amino acids (BCAAs), elements of essential amino acids, have been found altered in its catabolism in diabetes decades ago. However, the relationship between BCAAs and DM induced deterioration of pressure overloaded heart disease remains controversial. This study is aimed to investigate the particular effect of BCKA, a metabolite of BCAA, on myocardial injury induced by pressure overloaded. Primary cardiomyocytes were incubated with or without BCKA and followed by treatment with isoproterenol (ISO); then cell viability was detected by CCK8 and apoptosis was examined by TUNNEL stain and caspase-3 activity analysis. Compared to non-BCKA incubated group, BCKA incubation decreased cell survival and increased apoptosis concentration dependently. Furthermore, Western blot assay showed that mTORC2-Akt pathway was significantly inactivated by BCKA incubation. Moreover, overexpression of rictor, a vital component of mTORC2, significantly abolished the adverse effects of BCKA on apoptosis susceptibility of cardiomyocytes. These results indicate that BCKA contribute to vulnerability of cardiomyocytes in stimulated stress via inactivation of mTORC2-Akt pathway.

The effects of bolus supplementation of branched-chain amino acids on skeletal muscle mass, strength, and function in patients with rheumatic disorders during glucocorticoid treatment

OBJECTIVES

To test the effects of bolus supplementation of branched-chain amino acids (BCAA) on skeletal muscle mass, strength, and function in patients with rheumatic disorders taking glucocorticoid (GC).

METHODS

Patients with rheumatic disorders treated with prednisolone (≥10 mg/day) were randomized to ingest additional daily 12 g of BCAA (n = 9) or not (n = 9) for 12 weeks. At baseline, and 4, 8, and 12 weeks, they underwent bioelectrical impedance analysis, muscle strength and functional tests, and computed tomography analysis for cross-sectional area of mid-thigh muscle.

RESULTS

Disease activities of the patients were well controlled and daily GC dose was similarly reduced in both groups. Limb muscle mass was recovered in both groups. Whole-body muscle mass and muscle strength and functional mobility were increased only in BCAA (+) group. The effects of BCAA supplementation on recovering skeletal muscle mass were prominent in particular muscles including biceps femoris muscle.

CONCLUSIONS

This trial is the first-in-man clinical trial to demonstrate that BCAA supplementation might be safe and, at least in part, improve skeletal muscle mass, strength, and function in patients with rheumatic disorders treated with GC.

Impaired Follistatin Secretion in Cirrhosis

CONTEXT

Follistatin is a liver-derived inhibitor of the muscle-growth inhibitor myostatin. Reduction in acute follistatin release may help explain muscle loss in liver cirrhosis.

OBJECTIVE

The study aimed to investigate the capacity of acute follistatin release in patients with liver cirrhosis compared to healthy control participants.

DESIGN, SETTING, AND PARTICIPANTS

To experimentally increase the glucagon-insulin ratio (mimicking the hormonal effect of exercise), we infused glucagon/somatostatin (to inhibit insulin secretion) and compared the acute follistatin increase in eight male cirrhosis patients with eight healthy control participants. Patients and controls received 1-hour glucagon/somatostatin and saline infusions on 2 separate days.

MAIN OUTCOME MEASURE

Follistatin was measured during and 5 hours after termination of infusions.

RESULTS

The peak follistatin change was significantly decreased in patients with liver cirrhosis compared to healthy control participants (1.9 (interquartile range, 1.4-2.5) versus 3.6 (interquartile range, 3.0-4.0), respectively; P = .003). Patients with liver cirrhosis demonstrated significantly decreased amounts of appendicular lean mass compared to healthy controls (27.6 ± 3.8 vs 34.5 ± 2.9%, respectively; P = .001).

CONCLUSIONS

Patients with cirrhosis show impaired capacity to acutely secrete follistatin. The decrease in acute follistatin release may contribute to the loss of muscle mass in liver cirrhosis.

Nutrition and Alcoholic Liver Disease: Effects of Alcoholism on Nutrition, Effects of Nutrition on Alcoholic Liver Disease, and Nutritional Therapies for Alcoholic Liver Disease

Malnutrition is the most frequent and nearly universal consequence in alcoholic liver disease (ALD) that adversely affects clinical outcomes. Sarcopenia or skeletal muscle loss is the major component of malnutrition in liver disease. There are no effective therapies to prevent or reverse sarcopenia in ALD because the mechanisms are not well understood. Consequences of liver disease including hyperammonemia, hormonal perturbations, endotoxemia and cytokine abnormalities as well as the direct effects of alcohol and its metabolites contribute to sarcopenia in ALD. This article focuses on the prevalence, methods to quantify malnutrition, specifically sarcopenia and potential therapies including novel molecular targeted treatments.

Sarcopenia in Patients with Chronic Liver Disease: Can It Be Altered by Diet and Exercise?

Sarcopenia, a loss of muscle mass, is being increasingly recognized to have a deleterious effect on outcomes in patients with chronic liver disease. Factors related to diet and the inflammatory nature of chronic liver disease contribute to the occurrence of sarcopenia in these patients. Sarcopenia adversely influences quality of life, performance, morbidity, success of transplantation, and even mortality. Specific deficiencies in macronutrients (protein, polyunsaturated fatty acids) and micronutrients (vitamins C, D, and E, carotenoids, and selenium) have been linked to sarcopenia. Lessons learned from nutritional therapy in geriatric patient populations may provide strategies to manage sarcopenia in patients with liver disease. Combining diet modification and nutrient supplementation with an organized program of exercise may help ameliorate or even reverse the effects of sarcopenia on an already complex disease process.

Plasma Amino Acid Concentrations Predict Mortality in Patients with End-Stage Liver Disease

BACKGROUND

The liver plays a key role in amino acid metabolism. In former studies, a ratio between branched-chain and aromatic amino acids (Fischer's ratio) revealed associations with hepatic encephalopathy. Furthermore, low concentrations of branched-chain amino acids were linked to sarcopenia in literature. Encephalopathy and sarcopenia are known to dramatically worsen the prognosis. Aim of this study was to investigate a complex panel of plasma amino acids in the context of mortality in patients with end-stage liver disease.

METHODS

166 patients evaluated for orthotopic liver transplantation were included. 19 amino acids were measured from citrated plasma samples using mass spectrometry. We performed survival analysis for plasma amino acid constellations and examined the relationship to established mortality predictors.

RESULTS

33/166 (19.9%) patients died during follow-up. Lower values of valine (p<0.001), Fischer's ratio (p<0.001) and valine to phenylalanine ratio (p<0.001) and higher values of phenylalanine (p<0.05) and tyrosine (p<0.05) were significantly associated with mortality. When divided in three groups, the tertiles discriminated cumulative survival for valine (p = 0.016), phenylalanine (p = 0.024) and in particular for valine to phenylalanine ratio (p = 0.003) and Fischer's ratio (p = 0.005). Parameters were also significantly correlated with MELD and MELD-Na score.

CONCLUSIONS

Amino acids in plasma are valuable biomarkers to determine increased risk of mortality in patients with end-stage liver disease. In particular, valine concentrations and constellations composed of branched-chain and aromatic amino acids were strongly associated with prognosis. Due to their pathophysiological importance, the identified amino acids could be used to examine individual dietary recommendations to serve as potential therapeutic targets.

Rapid skeletal muscle wasting predicts worse survival in patients with liver cirrhosis

AIM

Sarcopenia impairs the outcome of patients with liver cirrhosis independently of liver function reserves. The aim of this study was to investigate whether the rate of skeletal muscle wasting predicts mortality in cirrhotic patients.

METHODS

This retrospective study evaluated 149 cirrhotic patients who visited our hospital between March 2004 and September 2012. The skeletal muscle cross-sectional area at the level of the third lumbar vertebra was measured by computed tomography, from which the skeletal muscle index was obtained for diagnosis of sarcopenia. The relative change in skeletal muscle area per year (ΔSMA/y) was calculated in each patient. Cox proportional hazards regression analysis was performed to evaluate risk factors for mortality.

RESULTS

Of the 149 cirrhotic patients, 94 (63%) were diagnosed with sarcopenia. The median of ΔSMA/y in all patients was -2.2%. For patients in Child-Pugh class A, B and C, ΔSMA/y was -1.3%, -3.5% and -6.1%, respectively. During a median follow-up period of 39 months (range, 1-110), 45 patients (30%) died. The optimal cut-off value of ΔSMA/y for predicting mortality was -3.1%; the survival rate in patients with ΔSMA/y of -3.1% or less was significantly lower than in patients with ΔSMA/y of more than -3.1% (P < 0.0001). The multivariate Cox proportional hazards model found ΔSMA/y of -3.1% or less to be significantly associated with mortality in cirrhotic patients (hazard ratio = 2.73, 95% confidence interval = 1.43-5.44, P < 0.01).

CONCLUSION

ΔSMA/y is useful for predicting mortality in patients with liver cirrhosis. Management of skeletal muscle may contribute toward improving the outcome of cirrhotic patients.

Astragalus polysaccharides decrease muscle wasting through Akt/mTOR, ubiquitin proteasome and autophagy signalling in 5/6 nephrectomised rats

ETHNOPHARMACOLOGICAL RELEVANCE

Existing evidences suggest that Radix Astragali and its polysaccharides composition (APS) can improve muscle mass, but the mechanisms need more research.

AIM OF THE STUDY

In this study, we aimed to examine the effects of APS on muscle wasting at molecular level in 5/6 nephrectomised rats.

MATERIALS AND METHODS

We performed 5/6 nephrectomy or sham operation in 160 6-week-old Sprague-Dawley rats, and feed animals with or without 2% APS for 155 days. After treatment, we compared the change of weight, muscle fibre, protein metabolism, pro-inflammatory factors (TNF-α, IL-15, CRP) and oxidative factors (MDA, SOD) among each group. In addition, we detected the Akt/mTOR, ubiquitin proteasome, autophagy signalling and AA transporters in vivo and in vitro.

RESULTS

Data in vivo show 2% APS could alleviate weight loss and improve protein metabolism in nephrectomised rats. The levels of serum pro-inflammatory factors and oxidative factors were restored by APS treatment. In molecular levels, APS restored Akt/mTOR, MAFbx, MuRF1, Atg7, LC3B-II/LC3B-I and SLC38A2 which changed in nephrectomised rats. Data in vitro show the optimal dose of APS is 0.2mg/mL, and SLC38A2 siRNA attenuated the effects of 0.2mg/mL APS on atrophy and autophagy.

CONCLUSIONS

Our results suggested APS could improve muscle wasting through Akt/mTOR, ubiquitin proteasome and autophagy signalling, and SLC38A2 may be one of potential targets.

Cause and management of muscle wasting in chronic liver disease

PURPOSE OF REVIEW

Sarcopenia or loss of skeletal muscle mass is the major component of malnutrition and occurs in the majority of patients with liver disease. Lower muscle contractile function also contributes to the adverse consequences of sarcopenia. There are no effective therapies to prevent or reverse sarcopenia in liver disease. This review will discuss the advances in diagnosis, pathogenesis, and treatment options for sarcopenia in liver disease.

RECENT FINDINGS

Sarcopenia increases mortality and risk of development of other complications of cirrhosis, and worsens postliver transplant outcomes while quality of life is decreased. Unlike other complications of cirrhosis that reverse after liver transplantation, sarcopenia may not improve and actually worsens. Impaired skeletal muscle protein synthesis and increased proteolysis via autophagy contribute to sarcopenia. Hyperammonemia is the best-studied mediator of the liver-muscle axis. Molecular studies show increased expression of myostatin whereas metabolic studies show impaired mitochondrial function and tricarboxylic acid cycle intermediates because of cataplerosis of α-ketoglutarate. Impaired skeletal muscle pyruvate and fatty acid oxidation during hyperammonemia suggest amino acids are diverted to acetyl CoA and potentially aggravate hyperammonemia. Nutritional supplementation is of limited or no benefit and suggests that cirrhosis is a state of anabolic resistance. Exercise may be beneficial but whether it overcomes anabolic resistance is not known.

SUMMARY

The high clinical significance of sarcopenia is well established. Current approaches to nutritional supplementation have not been effective in reversing sarcopenia because of anabolic resistance. Myostatin antagonists, specific amino acid supplementation, mitochondrial protection, and combination endurance-resistance exercise are potential future therapeutic options.

Review article: sarcopenia in cirrhosis--aetiology, implications and potential therapeutic interventions

BACKGROUND

Sarcopenia (loss of muscle mass) is common in cirrhosis and is associated with poor outcomes. Current teaching recommends the use of protein supplementation and exercise, however, this fails to address many other factors which contribute to muscle loss in this setting.

AIMS

To summarise existing knowledge regarding the aetiology of sarcopenia in cirrhosis, diagnostic modalities and the clinical significance of this condition. In addition to discuss recent research findings that may allow the development of more effective treatments.

METHODS

We conducted a Medline and PubMed search using the search terms 'sarcopenia', 'muscle', 'body composition', 'cirrhosis', 'liver' and 'malnutrition' from inception to October 2015.

RESULTS

Cirrhotic patients with sarcopenia have reduced survival, experience increased rates of infection and have worse outcomes following liver transplantation. The aetiology of this condition is more complex than simple protein and calorie malnutrition. Cirrhosis also results in depleted glycogen stores and metabolic alterations that cause excessive protein catabolism, increased activation of the ubiquitin-proteasome pathway and inappropriate muscle autophagy. Satellite cell differentiation and proliferation is also reduced due to a combination of elevated myostatin levels, reduced IGF-1 and hypogonadism. Although there is some evidence supporting the use of late evening snacks, branched chain amino acid supplementation and high protein/high calorie diets, well designed clinical trials addressing the effects of treatment on body composition in cirrhosis are lacking.

CONCLUSION

Sarcopenia in cirrhosis has a complex pathogenesis and simple dietary interventions are insufficient. Improved understanding of the multiple mechanisms involved should allow the development of more effective therapies, which target the specific underlying metabolic derangements.

Nutrition therapy: Integral part of liver transplant care

Managing malnutrition before liver transplantation (LTx) while on the waiting list and, excessive weight gain/metabolic disturbances in post-surgery are still a challenge in LTx care. The aim of this review is to support an interdisciplinary nutrition approach of these patients. Cirrhotic patients are frequently malnourished before LTx and this is associated with a poor prognosis. Although the relation between nutritional status versus survival, successful operation and recovery after LTx is well established, prevalence of malnutrition before the operation is still very high. Emerging research has also demonstrated that sarcopenia pre and post-transplant is highly prevalent, despite the weight gain in the postoperative period. The diagnosis of the nutritional status is the first step to address the adequate nutritional therapy. Nutritional recommendations and therapy to manage the nutritional status of LTx patients are discussed in this review, regarding counseling on adequate diets and findings of the latest research on using certain immunonutrients in these patients (branched chain amino-acids, pre and probiotics). Nutrition associated complications observed after transplantation is also described. They are commonly related to the adverse effects of immunosuppressive drugs, leading to hyperkalemia, hyperglycemia and weight gain. Excessive weight gain and post-transplant metabolic disorders have long been described in post-LTx and should be addressed in order to reduce associated morbidity and mortality.

Nutrition in liver transplantation: too little or too much?

PURPOSE OF REVIEW

The purpose of this study was to review the most recent findings on approaches to managing the obesity and muscle wasting that are found in patients before and after liver transplantation.

RECENT FINDINGS

A number of articles have contributed to the accumulating evidence that morbid obesity is not an absolute contraindication to liver transplantation with survival outcomes similar across BMI groups. Obesity is, however, a risk factor for early post-transplant complications and obesity-related comorbidities markedly increase this risk. Very limited data are as yet available, dietary, or otherwise, related to amelioration of these comorbidities and evidence that weight loss leads to improved outcomes in obese patients is lacking. Abdominal computed tomography imaging is increasingly being used to identify muscle wasting, and poorer post-transplant survival is seen in patients with significant muscle wasting. This modality has confirmed the persistence of depleted muscle stores after transplant extending well beyond 1 year. Coupled with this is a high incidence of weight gain and metabolic syndrome and the associated risks. Although dietary intervention and exercise are considered possible approaches to address these issues, work in these areas so far is sparse.

SUMMARY

An urgent need exists for interventional studies on the basis of nutrition and/or exercise to address the challenges presented by both obesity and muscle wasting, which likely coexist in many patients in both the pretransplant and the post-transplant periods.

Myostatin: expanding horizons

Myostatin is a secreted growth and differentiation factor that belongs to the TGF-β superfamily. Myostatin is predominantly synthesized and expressed in skeletal muscle and thus exerts a huge impact on muscle growth and function. In keeping with its negative role in myogenesis, myostatin expression is tightly regulated at several levels including epigenetic, transcriptional, post-transcriptional, and post-translational. New revelations regarding myostatin regulation also offer mechanisms that could be exploited for developing myostatin antagonists. Increasingly, it is becoming clearer that besides its conventional role in muscle, myostatin plays a critical role in metabolism. Hence, molecular mechanisms by which myostatin regulates several key metabolic processes need to be further explored.

Impact of muscle wasting on survival in patients with liver cirrhosis

Muscle wasting is defined as the progressive and generalized loss of muscle mass. Muscle depletion is a common feature of chronic liver disease found in approximately 40% of patients with cirrhosis. Its etiology is multifactorial subsequent to liver failure and its prevalence increases along with disease severity. Cross-sectional analytic morphometry using computed tomography (CT) scan or magnetic resonance imaging are considered by consensus the gold standards to assess muscle size in cirrhosis for research purposes because they are not biased by fluid accumulation. Several studies have assessed the impact of muscle wasting on overall survival of patients in the waiting list for liver transplantation and there is a general agreement that decreased muscle size assessed by CT scan is an independent predictor for mortality in cirrhosis. It has been proposed that the addition of cross-sectional muscle area into the Model for End-stage Liver Disease can increase its prognostic performance. Nevertheless, the use of CT scan in assessing muscle size is inappropriate for routine clinical practice and an alternative cost-effective, easy to use and accurate tool should be developed. In conclusion, muscle wasting has a detrimental impact on survival of patients with cirrhosis and, thus, it remains to be elucidated if nutritional interventions and exercise could improve muscle wasting and, subsequently, survival in this setting.

Skeletal muscle depletion predicts the prognosis of patients with hepatocellular carcinoma treated with sorafenib

The aim of this study was to determine whether skeletal muscle depletion predicts the prognosis of patients with hepatocellular carcinoma (HCC) that is being treated with sorafenib. We evaluated 40 consecutive HCC patients who received sorafenib treatment. The skeletal muscle cross-sectional area was measured by computed tomography at the third lumbar vertebra (L3), from which the L3 skeletal muscle index (L3 SMI) was obtained. The factors contributing to overall survival, sorafenib dose reduction, and discontinuation of sorafenib were analyzed using the Cox proportional hazards model. L3 SMI (p = 0.020) and log (α-fetoprotein (AFP)) (p = 0.010) were identified as independent prognostic factors in HCC patients treated with sorafenib. The initial dose of sorafenib (p = 0.008) was an independent risk factor for sorafenib dose reduction, and log (AFP) (p = 0.008) was the only significant risk factor for the discontinuation of this drug. L3 SMI was not a risk factor for either dose reduction (p = 0.423) or the discontinuation (p = 0.132) of sorafenib. A multiple linear regression analysis determined the following relationship between skeletal muscle mass (assessed as L3 SMI) and the explanatory factors: L3 SMI = −0.1896 × (Age) − 10.3441 × (Child-Pugh score) − 9.3922 × (log (AFP)) + 1.6139 × (log (AFP)) × (Child-Pugh score) + 112.9166. Skeletal muscle depletion is inversely associated with age, Child-Pugh score, and log (AFP). Moreover, it is an independent prognostic factor for HCC patients treated with sorafenib.