Sarcopenia is associated with severe liver fibrosis in patients with non-alcoholic fatty liver disease

Gene-Environmental Interactions as Metabolic Drivers of Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) has emerged as a leading cause of chronic liver disease worldwide in the past few decades as a consequence of the global obesity epidemic and is associated with significant morbidity and mortality. NAFLD is closely associated with components of the metabolic syndrome, type 2 diabetes mellitus and cardiovascular disease, suggesting a plausible metabolic mechanistic basis. Metabolic inflexibility is considered a nidus for NAFLD pathogenesis, causing lipotoxicity, mitochondrial dysfunction and cellular stress leading to inflammation, apoptosis and fibrogenesis, thus mediating disease progression into nonalcoholic steatohepatitis (NASH) and ultimately cirrhosis. In this review, we describe they key metabolic drivers that contribute to development of NAFLD and NASH, and we explain how NASH is a metabolic disease. Understanding the metabolic basis of NASH is crucial for the prevention and treatment of this disease.

Women Have a Lower Risk of Nonalcoholic Fatty Liver Disease but a Higher Risk of Progression vs Men: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

The risk of nonalcoholic fatty liver disease (NAFLD) and its progression may differ between men and women. We conducted a systematic review and meta-analysis to determine the relationship between sex and NAFLD, nonalcoholic steatohepatitis (NASH), and advanced NAFLD fibrosis.

METHODS

Studies reporting sex-stratified NAFLD prevalence among population-based samples and either NASH or advanced fibrosis among patients with biopsy-proven NAFLD were identified from MEDLINE, EMBASE, and Cochrane databases through December 2017. We calculated pooled relative risk ratios comparing women vs men for each outcome.

RESULTS

Our final analysis comprised 54 studies. Samples sizes were 62,239 for the NAFLD analysis, 5428 for the NASH analysis, and 6444 for the advanced fibrosis analysis. Women had a 19% lower risk of NAFLD than men in the general population (pooled risk ratio [RR], 0.81; 95% CI, 0.68-0.97; I² = 97.5%). Women had a similar risk of NASH (RR, 1.00; 95% CI, 0.88-1.14; I² = 85.1%), and a 37% higher risk of advanced fibrosis (RR, 1.37; 95% CI, 1.12-1.68; I² = 74.0%) than men. Age modified the effect of sex on NAFLD severity. Risks of NASH (RR, 1.17; 95% CI, 1.01-1.36) and advanced fibrosis (RR, 1.56; 95% CI, 1.36-1.80; I² = 0) were substantially higher in women in study populations with average ages of 50 years and older; sex differences in NASH and advanced fibrosis were attenuated in younger populations.

CONCLUSIONS

In a systematic review and meta-analysis, we found women to have a lower risk of NAFLD than men. However, once NAFLD is established, women have a higher risk of advanced fibrosis than men, especially after age 50 years.

Hepatic Steatosis Contributes to the Development of Muscle Atrophy via Inter-Organ Crosstalk

Individuals with hepatic steatosis often display several metabolic abnormalities including insulin resistance and muscle atrophy. Previously, we found that hepatic steatosis results in an altered hepatokine secretion profile, thereby inducing skeletal muscle insulin resistance via inter-organ crosstalk. In this study, we aimed to investigate whether the altered secretion profile in the state of hepatic steatosis also induces skeletal muscle atrophy via effects on muscle protein turnover. To investigate this, eight-week-old male C57BL/6J mice were fed a chow (4.5% fat) or a high-fat diet (HFD; 45% fat) for 12 weeks to induce hepatic steatosis, after which the livers were excised and cut into ~200-µm slices. Slices were cultured to collect secretion products (conditioned medium; CM). Differentiated L6-GLUT4myc myotubes were incubated with chow or HFD CM to measure glucose uptake. Differentiated C2C12 myotubes were incubated with chow or HFD CM to measure protein synthesis and breakdown, and gene expression via RNA sequencing. Furthermore, proteomics analysis was performed in chow and HFD CM. It was found that HFD CM caused insulin resistance in L6-GLUT4myc myotubes compared with chow CM, as indicated by a blunted insulin-stimulated increase in glucose uptake. Furthermore, protein breakdown was increased in C2C12 cells incubated with HFD CM, while there was no effect on protein synthesis. RNA profiling of C2C12 cells indicated that 197 genes were differentially expressed after incubation with HFD CM, compared with chow CM, and pathway analysis showed that pathways related to anatomical structure and function were enriched. Proteomics analysis of the CM showed that 32 proteins were differentially expressed in HFD CM compared with chow CM. Pathway enrichment analysis indicated that these proteins had important functions with respect to insulin-like growth factor transport and uptake, and affect post-translational processes, including protein folding, protein secretion and protein phosphorylation. In conclusion, the results of this study support the hypothesis that secretion products from the liver contribute to the development of muscle atrophy in individuals with hepatic steatosis.

Skeletal Muscle Dysfunction in the Development and Progression of Nonalcoholic Fatty Liver Disease

The association between the pathogenesis and natural course of nonalcoholic fatty liver disease (NAFLD) and skeletal muscle dysfunction is increasingly recognized. These obesity-associated disorders originate primarily from sustained caloric excess, gradually disrupting cellular and molecular mechanisms of the adipose-muscle-liver axis resulting in end-stage tissue injury exemplified by cirrhosis and sarcopenia. These major clinical phenotypes develop through complex organ-tissue interactions from the earliest stages of NAFLD. While the role of adipose tissue expansion and remodeling is well established in the development of NAFLD, less is known about the specific interplay between skeletal muscle and the liver in this process. Here, the relationship between skeletal muscle and liver in various stages of NAFLD progression is reviewed. Current knowledge of the pathophysiology is summarized with the goal of better understanding the natural history, risk stratification, and management of NAFLD.

Harnessing Muscle-Liver Crosstalk to Treat Nonalcoholic Steatohepatitis

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

Epidemiology, Pathogenesis, Diagnosis and Emerging Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, with an estimated rising prevalence, in concert with the epidemics of obesity and type 2 diabetes. The pathogenesis of NAFLD is not fully elucidated. Besides weight gain and insulin resistance, many other factors seem to contribute, including adipokines, gut microbiota and genetic predisposition. The disease starts as hepatic steatosis, which may proceed to nonalcoholic steatohepatitis (NASH); if fibrosis is added, the risk of cirrhosis and/or hepatocellular carcinoma is augmented. Liver biopsy is considered the gold standard for the diagnosis and staging of NAFLD; the early use of reliable and easily applied diagnostic tools, such as noninvasive biomarkers, is needed to identify patients at different-preferably early-stages of disease however. Whilst lifestyle modification is the first step to manage NAFLD, there is poor compliance, leading to the need of drug therapy. Accordingly, a variety of medications is under investigation. Given the multifaceted pathophysiology of NAFLD, probably, a combination of approaches in an individualized basis may be a more appropriate management. This review summarizes evidence on the epidemiology, pathogenesis, diagnosis and treatment of NAFLD.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

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

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

Nonalcoholic Fatty Liver Disease and Sarcopenia: Where Do We Stand?

The link between metabolic syndrome (MetS) and sarcopenia has not been extensively studied, but it is evident that they share several common features. Crucial mechanisms involved in sarcopenia-nonalcoholic fatty liver disease (NAFLD) interplay are based on effects of insulin resistance, chronic inflammation, oxidative stress, and crosstalk between organs by secretion of cytokines (hepatokines, adipokines, and myokines). Currently, published studies confirm the association of sarcopenia with the degree of NAFLD defined by liver histology. However, prospective studies that will give us information regarding the causal effect of NAFLD and sarcopenia are still needed. Furthermore, there is a need for a patient-friendly, noninvasive, low-cost method for detection of loss of skeletal muscle mass, strength, and physical performance in the context of NAFLD. Moreover, potential treatment strategies such as physical exercise and nutritional supplementation, that are usually a part of management of sarcopenia, should also be investigated in NAFLD patients, especially given the fact that for now, we do not have a good treatment option for NAFLD. Therefore, future investigations should combine studies on NAFLD and sarcopenia in terms of physical activity and nutritional interventions such as vitamin D supplementation. This review aims to report recent evidence concerning the links between sarcopenia and NAFLD and methods to assess sarcopenia.

Clinical assessment and management of liver fibrosis in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is among the most frequent etiologies of cirrhosis worldwide, and it is associated with features of metabolic syndrome; the key factor influencing its prognosis is the progression of liver fibrosis. This review aimed to propose a practical and stepwise approach to the evaluation and management of liver fibrosis in patients with NAFLD, analyzing the currently available literature. In the assessment of NAFLD patients, it is important to identify clinical, genetic, and environmental determinants of fibrosis development and its progression. To properly detect fibrosis, it is important to take into account the available methods and their supporting scientific evidence to guide the approach and the sequential selection of the best available biochemical scores, followed by a complementary imaging study (transient elastography, magnetic resonance elastography or acoustic radiation force impulse) and finally a liver biopsy, when needed. To help with the selection of the most appropriate method a Fagan's nomogram analysis is provided in this review, describing the diagnostic yield of each method and their post-test probability of detecting liver fibrosis. Finally, treatment should always include diet and exercise, as well as controlling the components of the metabolic syndrome, +/- vitamin E, considering the presence of sleep apnea, and when available, allocate those patients with advanced fibrosis or high risk of progression into clinical trials. The final end of this approach should be to establish an opportune diagnosis and treatment of liver fibrosis in patients with NAFLD, aiming to decrease/stop its progression and improve their prognosis.

Relative fat mass at baseline and its early change may be a predictor of incident nonalcoholic fatty liver disease

The relationship between changes in body components and the risk of nonalcoholic fatty liver disease (NAFLD) is not fully understood. We investigated the effects of body components and subsequent changes on incident NAFLD at follow-up ultrasound scanning in a longitudinal cohort. We included 9967 participants without NAFLD at baseline who underwent serial health examinations. Sex-specific, weight-adjusted skeletal muscle index (SMI_{_Wt}) was used. Mean follow-up duration was 48.5 ± 33.5 months. NAFLD developed in 2395 participants (24.0%). Body composition was measured using bioelectrical impedance analysis. The following baseline body components were significantly associated with incident NAFLD: the lowest and middle SMI_{_Wt} tertiles in the normal-weight group (adjusted hazard ratio [aHR] = 2.20 and 1.54, respectively), and fat percentage in the normal-weight (aHR = 1.12), overweight (aHR = 1.05), and obese groups (aHR = 1.03) (all P < 0.05). Among 5,033 participants who underwent ≥ 3 health examinations, SMI_{_Wt} increase between the first and second examinations was an independent protective factor against incident NAFLD in non-obese groups (P < 0.05). Increased fat percentage was an independent risk factor for incident NAFLD in all weight categories (P < 0.05). High fat mass at baseline may be a better predictor of incident NAFLD than muscle mass. Reciprocal changes in fat and muscle mass during the first year of follow-up predicted incident NAFLD in non-obese groups.

Association between Atrial Fibrillation and Advanced Liver Fibrosis in Patients with Non-Alcoholic Fatty Liver Disease

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is independently associated with the development of atrial fibrillation (AF). However, the association of AF with advanced liver fibrosis, which is related to all-cause, cardiovascular, and liver-related mortality, has not been established in NAFLD patients. We aimed to investigate the association between AF and advanced liver fibrosis in NAFLD patients.

MATERIALS AND METHODS

Out of 53704 adults who participated in the health check-up program, 6293 subjects aged 35 years and older were diagnosed as NAFLD using ultrasound. The stage of liver fibrosis was assessed based on the newly adjusted NAFLD fibrosis score (NFS) and Fibrosis-4 (Fib-4) Index, which were used to determine the low and high cut-off values (COVs).

RESULTS

Of 6293 patients with NAFLD, 59 (0.9%) were diagnosed with AF. Patients with AF were older (52.0 vs. 64.6 years, p<0.001), had higher body mass index (25.2 vs. 26.6 kg/m², p<0.001), and had bigger waist circumference (84.0 vs. 89.9 cm, p<0.001) than those without AF. In NAFLD patients, AF was independently associated with advanced liver fibrosis, assessed using both COVs of NFS [low-COV group: final adjusted odds ratios (aORs)=2.85, p=0.004; high-COV group: ORs=12.29, p<0.001). AF was independently associated with advanced liver fibrosis, assessed using both COVs of Fib-4 (low-COV group: aORs=2.49, p<0.001; high-COV group: aORs=3.84, p=0.016).

CONCLUSION

AF is independently associated with advanced liver fibrosis in patients with NAFLD.

Established and emerging factors affecting the progression of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease affecting approximately 25% of the global population. Although a majority of NAFLD patients will never experience liver-related symptoms it is estimated that 5-10% will develop cirrhosis-related complications with risk of death or need for liver transplantation. NAFLD is closely associated with cardiovascular disease and components of the metabolic syndrome. However, NAFLD is not uncommon in lean individuals and may in these subjects represent a different entity with separate pathophysiological mechanisms involved implying a higher risk for development of end-stage liver disease. There is considerable fluctuation in the histopathological course of NAFLD that may partly be attributed to lifestyle factors and dietary composition. Nutrients such as fructose, monounsaturated fatty acids, and trans-fatty acids may aggravate NAFLD. Presence of type 2 diabetes mellitus seems to be the most important clinical predictor of liver-related morbidity and mortality in NAFLD. Apart from severity of the metabolic syndrome, genetic polymorphisms and environmental factors, such as moderate alcohol consumption, may explain the variation in histopathological and clinical outcome among NAFLD patients.

WITHDRAWN: Higher appendicular skeletal muscle mass percentage is an independent protective factor for non-alcoholic steatohepatitis and significant fibrosis in male with NAFLD

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Contribution of sarcopenia and physical inactivity to mortality in people with non-alcoholic fatty liver disease

Background & Aims

Physical inactivity and sedentary lifestyle have contributed to the epidemic of obesity and non-alcoholic fatty liver disease (NAFLD). We assessed the association between physical activity, NAFLD, and sarcopenia, and their contributions to mortality.

Methods

Data from the National Health and Nutrition Examination Survey (NHANES) 1999-2004 with Linked Mortality file (through 2015) was utilised. NAFLD was determined by the US Fatty Liver Index in the absence of secondary causes of liver disease. Sarcopenia was defined using appendicular lean mass divided by body mass index by the Foundation for the National Institutes of Health criteria. Activity level was determined using standard self-reports. Publicly available imputed dual-energy X-ray absorptiometry data sets were used.

Results

Of 4,611 NHANES participants (48.2% males; 72.5% White; mean age 45.9 years), NAFLD was present in 1,351 (29.3%), of whom 17.7% had sarcopenia. Of the NAFLD group, 46.3% was inactive, whilst intermediate and ideal physical activity rates were observed in 14.2% and 39.5%, respectively. Sarcopenia was significantly and inversely related to higher physical activity level, both amongst NAFLD (odds ratio [OR] = 0.45 [95% CI 0.30-0.69]) and non-NAFLD (OR = 0.51 [0.35-0.75]) groups. During a median follow-up of 13.5 years, a total of 586 subjects died, of whom 251 had NAFLD. Amongst those who died with NAFLD, 33.0% had sarcopenia and 54.3% were inactive. Compared with NAFLD without sarcopenia, NAFLD with sarcopenia was associated with a higher risk of all-cause (hazard ratio [HR] = 1.78 [1.16-2.73]), cardiac-specific (HR = 3.19 [1.17-8.74]), and cancer-specific mortality (HR = 2.12 [1.08-4.15]).

Conclusions

Inactivity is associated with presence of sarcopenia, whilst sarcopenia is associated with increased mortality amongst NAFLD patients. Sarcopenia should be a part of clinical assessment of patients with NAFLD. Treatment of NAFLD should include optimal management of sarcopenia.

Lay summary

Nonalcoholic fatty liver disease (NAFLD) and sarcopenia have similar pathophysiological profiles. Our data show that sarcopenia is associated with inactivity in subjects with NAFLD. The presence of sarcopenia in patients with NAFLD poses increased risk for all-cause and cardiac-specific mortality.

Muscle Mass Is Linked to Liver Disease Severity in Pediatric Nonalcoholic Fatty Liver Disease

OBJECTIVE

To investigate the association between muscle mass and liver disease severity in pediatric patients with non-alcoholic fatty liver disease (NAFLD).

STUDY DESIGN

This was a retrospective study of patients aged <20 years followed from 2009 to 2018. Muscle mass was estimated in all patients by measuring magnetic resonance imaging-based total psoas muscle surface area (tPMSA) and correcting for height (tPMSA index = tPMSA/height2). Two cohorts were studied, one with histological confirmation of NAFLD (n = 100) and the other with magnetic resonance imaging (MRI) evidence of hepatic steatosis (n = 236). Histology was scored using Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) criteria. MRI-measured proton density fat fraction (PDFF) and liver stiffness were collected. Demographic, clinical, and socioeconomic status (using a validated Community Deprivation Index [CDI]) were assessed as covariates. Univariate regression analyses, followed by multivariable regression analyses, were used to determine the relationships between tPMSA index and NAS, MRI-PDFF, and liver stiffness, adjusting for clinical, demographic, and CDI variables.

RESULTS

In the multivariable regression analyses, higher steatosis score was associated with a lower tPMSA index (OR, 0.73; 95% CI, 0.56-0.96) and younger age (OR, 0.84; 95% CI, 0.73-0.97). Liver PDFF was also significantly associated with the tPMSA index (P = .029), sex (P = .019), and CDI (P = .005). In contrast, liver stiffness was not associated with tPMSA in multivariable analyses.

CONCLUSIONS

tPMSA index was independently associated with both imaging and histological features of hepatic steatosis severity in children. Future studies should directly explore the presence and directionality of causative links between muscle mass and steatosis, as well as whether interventions that enhance muscle mass can reduce disease severity in children with NAFLD.

Creatinine/(cystatin C × body weight) ratio is associated with skeletal muscle mass index

We have previously reported that the creatinine (Cre) to cystatin C (CysC) ratio is associated with height-adjusted skeletal muscle mass index (SMI). However, weight-adjusted SMI is reported to be a more useful marker of insulin sensitivity than height-adjusted SMI. Thus, we hypothesized that the creatinine to (cystatin C × body weight [BW]) relationship (Cre/[CysC × BW]) might be associated with weight-adjusted SMI. In this cross-sectional study of 169 males and 132 females, a body composition analyzer was used and the weight-adjusted SMI was calculated as (absolute muscle mass [kg]/BW [kg]) × 100. The cut-off of low muscle mass was defined as weight-adjusted SMI <37.0% for males and <28.0% for females. The Cre/(CysC × BW) was correlated with weight-adjusted SMI in both males (r = 0.484, p < 0.001) and females (r = 0.538, p < 0.001). In addition, Cre/(CysC × BW) was associated with weight-adjusted SMI in both males (standardized β = 0.493, p < 0.001) and females (standardized β = 0.570, p < 0.001) after adjusting for covariates. According to the receiver operator characteristic (ROC) curve analysis, the optimal cut-off point of Cre/(CysC × BW) for low muscle mass was 0.0145 (area under the ROC curve [AUC] 0.756 [95% confidence interval {95% CI} 0.644-0.842], sensitivity = 0.96, specificity = 0.47, p < 0.001) in males and 0.0090 (AUC 0.976 [95% CI 0.894-0.995], sensitivity = 1.00, specificity = 0.93, p < 0.001) in females. There is a correlation between Cre/(CysC × BW) and weight-adjusted SMI. The Cre/(CysC × BW) could be a practical screening marker for low muscle mass.

Verification of the Nutritional and Dietary Factors Associated with Skeletal Muscle Index in Japanese Patients with Nonalcoholic Fatty Liver Disease

We sought to identify the frequencies of presarcopenia, sarcopenia, and sarcopenic obesity in patients with nonalcoholic fatty liver disease (NAFLD) and to cross-sectionally determine the nutritional and dietary factors associated with loss of skeletal muscle mass in such patients. Dietary and body component changes produced by a diet intervention were longitudinally investigated. Forty-six NAFLD patients (24 males and 22 females) were enrolled. A second diet treatment was performed at 6 months after entry in 19 of the enrolled patients (6 males and 13 females). Body compositions and dietary nutrients at six months later were compared with those at entry. Three of the 24 (13%) males and four of the 22 (18%) females fulfilled the criteria for presarcopenia and one (5%) female NAFLD patient was in the criteria for sarcopenia at baseline. None of the patients were in the criteria for sarcopenic obesity. The factors associated with skeletal muscle index in the males were body mass index (BMI), insulin-like growth factor-1, total energy intake, and lipid intake, but only BMI and bone mineral density in females at baseline. The diet intervention decreased the skeletal muscle mass in the 6 males by decreasing the total energy intake via lower protein and lipid intakes and improved their liver dysfunction. In the 13 females, a decrease in total energy intake via lower carbohydrate and lipid intake did not change the skeletal muscle mass. These results suggest that loss of skeletal muscle mass is frequently observed in nonobese NAFLD patients and that the frequency of sarcopenic obesity seems to be rare in NAFLD patients. The nutritional and dietary factors that regulate loss of skeletal muscle mass were distinct between our male and female NAFLD patients. Thus, the skeletal muscle mass of such patients as well as their body weight and liver function should be monitored during diet interventions.

Liver Stiffness Is Associated With Progression of Albuminuria in Adults With Type 2 Diabetes: Nonalcoholic Fatty Disease Cohort Study

OBJECTIVES

Previous studies have shown the association between liver fibrosis and albuminuria. However, the effect of liver fibrosis on change in albuminuria is unclear. Thus, we investigated the effect of liver fibrosis on change in albuminuria in patients with type 2 diabetes.

METHODS

In this retrospective cohort study, we assessed 105 patients with type 2 diabetes concomitant with nonalcoholic fatty disease. A change in urinary albumin excretion (UAE) was defined as follows: change in UAE=(logarithm [UAE+1] at follow-up examination minus logarithm [UAE+1] at baseline examination) / follow-up duration (1 year in this study). Elastography was performed to assess controlled attenuation parameter (dB/m) and liver stiffness measurement (LSM; kPa) values.

RESULTS

Mean (standard deviation) data were as follows: age, 63.3 (12.1) years; body mass index, 25.4 (4.3) kg/m²; controlled attenuation parameter, 273.1 (53.0) dB/m; and LSM, 6.2 (3.4) kPa. Median UAE value (interquartile range) was 16 (6 to 43) mg/g creatinine. LSM was associated with changes in UAE (r=0.27, p=0.005). Multiple regression analysis demonstrated that LSM was associated with change in UAE (β=0.28, p=0.015) after adjusting for sex, age, duration of diabetes, smoking status, exercise habits, glycated hemoglobin, body mass index, estimated glomerular filtration rate, systolic blood pressure, logarithm (UAE+1) at baseline examination, use of renin‒angiotensin system inhibitors, new use of sodium glucose cotransporter-2 inhibitors and glucagon-like peptide-1 and controlled attenuation parameter.

CONCLUSIONS

Liver stiffness is an independent risk factor for the progression of albuminuria in patients with type 2 diabetes.

Epidemiology of nonalcoholic fatty liver disease in non-obese populations: Meta-analytic assessment of its prevalence, genetic, metabolic, and histological profiles

OBJECTIVE

As a subgroup of nonalcoholic fatty liver disease (NAFLD), patients with non-obese NAFLD may also have an increased risk of adverse hepatic and metabolic outcomes. We aimed to estimate the prevalence and incidence of non-obese NAFLD and to describe its clinical characteristics in this systematic review and meta-analysis.

METHODS

We performed a systematic search of 1235 citations published up to Mar 2020. Meta-analyses, stratified analyses and meta-regression were all performed.

RESULTS

Of the 46 studies included, 28 cross-sectional and longitudinal studies of 155 846 non-obese participants reported a pooled NAFLD prevalence of 14.5% (95% confidence interval [CI] 12.3%-17.1%). A multivariate meta-regression analysis showed the trend that the prevalence varied by their geographical location. Further stratified analyses showed that NAFLD was relatively prevalent among people aged ≥45 years (16.2%; 95% CI 10.8-23.4) and those in South America (25.7%; 95% CI 24.4-27.0). The PNPLA3 rs738409 gene polymorphism was more frequently observed in non-obese NAFLD than in both obese NAFLD and non-obese controls, while the metabolic profiles of non-obese NAFLD were less severe than those of the obese NAFLD group. Patients with non-obese NAFLD had 4.81-fold and 5.43-fold higher risk of diabetes mellitus and metabolic syndrome, respectively, than the non-obese controls.

CONCLUSIONS

Non-obese NAFLD is common, particularly in South America and among people aged ≥45 years. Metabolic diseases and PNPLA3 rs738409 gene polymorphism are more frequent in the non-obese NAFLD group than in non-obese controls.

Noninvasive Evaluation of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver diseases and can progress to advanced fibrosis and end-stage liver disease. Thus, intensive research has been performed to develop noninvasive methods for the diagnosis of nonalcoholic steatohepatitis (NASH) and fibrosis. Currently, no single noninvasive tool covers all of the stages of pathologies and conditions of NAFLD, and the cost and feasibility of known techniques are also important issues. Blood biomarkers for NAFLD may be useful to select subjects who need ultrasonography (US) screening for NAFLD, and noninvasive tools for assessing fibrosis may be helpful to exclude the probability of significant fibrosis and to predict advanced fibrosis, thus guiding the decision of whether to perform liver biopsy in patients with NAFLD. Among various methods, magnetic resonance-based methods have been shown to perform better than other methods in assessing steatosis as well as in detecting hepatic fibrosis. Many genetic markers are associated with the development and progression of NAFLD. Further well-designed studies are needed to determine which biomarker panels, imaging studies, genetic marker panels, or combinations thereof perform well for diagnosing NAFLD, differentiating NASH and fibrosis, and following-up NAFLD, respectively.

Non-Alcoholic Fatty Liver Disease in Patients with Type 2 Diabetes Mellitus: A Position Statement of the Fatty Liver Research Group of the Korean Diabetes Association

This clinical practice position statement, a product of the Fatty Liver Research Group of the Korean Diabetes Association, proposes recommendations for the diagnosis, progression and/or severity assessment, management, and follow-up of non-alcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM). Patients with both T2DM and NAFLD have an increased risk of non-alcoholic steatohepatitis (NASH) and fibrosis and a higher risk of cardiovascular diseases and diabetic complications compared to those without NAFLD. With regards to the evaluation of patients with T2DM and NAFLD, ultrasonography-based stepwise approaches using noninvasive biomarker models such as fibrosis-4 or the NAFLD fibrosis score as well as imaging studies such as vibration-controlled transient elastography with controlled attenuation parameter or magnetic resonance imaging-proton density fat fraction are recommended. After the diagnosis of NAFLD, the stage of fibrosis needs to be assessed appropriately. For management, weight reduction achieved by lifestyle modification has proven beneficial and is recommended in combination with antidiabetic agent(s). Evidence that some antidiabetic agents improve NAFLD/NASH with fibrosis in patients with T2DM is emerging. However, there are currently no definite pharmacologic treatments for NAFLD in patients with T2DM. For specific cases, bariatric surgery may be an option if indicated.

Sarcopenia in chronic liver diseases: a translational overview

INTRODUCTION

Sarcopenia refers to a progressive and generalized muscle mass and strength loss. In liver diseases, it has been related to worse outcomes and high risk of decompensations.

AREAS COVERED

Sarcopenia is caused by a set of cellular processes in the muscle such as denervation, mitochondrial dysfunction, endotoxemia and inflammation; which are manifested through the alteration of several proteolytic pathways such as lysosomal, proteasomal and caspase systems. In autophagy, myostatin and oxidative stress; such as hyperammonemia, contributes importantly to liver sarcopenia through loss of muscle mass already demonstrated in in vitro and in vivo models. In addition, hormones and the regulation of the intestinal microbiota, influence in a not less important magnitude. In the clinical setting, early identification of sarcopenia has been established as a mandatory item to prevent progression of muscle mass loss; however, diagnostic methods have extreme variation according to methodology, population, etiology and severity of liver disease. Reversing sarcopenia should be an integral therapeutic strategy.

EXPERT OPINION

Clinical and nutritional interventions should be adapted to liver injury etiology and stage of disease, each of them shares a similar sarcopenia development pathway. There are specific biomarkers that condition or exacerbate loss of skeletal muscle.

Nonalcoholic Fatty Liver Disease Is Associated With Low Skeletal Muscle Mass in Overweight/Obese Youths

Background: Recent studies in adult non-elderly and elderly individuals have reported a link between nonalcoholic fatty liver disease (NAFLD) and sarcopenia. Nonetheless, whether this relationship would be found outside these populations it is still unknown. Hence, we evaluated the relationship between NAFLD and skeletal muscle mass in children and adolescents with overweight/obesity. Methods: Two-hundred and thirty-four overweight/obese youths were enrolled. NAFLD was diagnosed by ultrasononography, after exclusion of infectious and metabolic disorders. Forty of the patients with NAFLD had also liver biopsy. Total and regional lean body mass and total fat mass measurements were obtained by dual-energy X-ray absorptiometry. The relative muscle mass (RMM) was defined as the percent of muscle mass (kg) relative to the sum of muscle and fat (kg) mass. Appendicular skeletal muscle mass (ASM) was calculated by the sum of muscle masses of the four limbs (kg), and expressed as percent of body weight. Results: Subjects were stratified according to tertiles of RMM. The prevalence of abdominal obesity, dyslipidemia, insulin resistance, metabolic syndrome, NAFLD as well as biopsy-proven nonalcoholic steatohepatitis (NASH) was significantly increased in the lowest tertile of RMM. After controlling for age, sex and Tanner stage, children in the lowest tertile of RMM had an increased risk for NAFLD (OR= 2.80, 95% CI=1.57-5.02) compared to those in the other two tertiles. This association persisted after additional adjustments for clinical and metabolic variables. Similarly, the risk of NAFLD in the lowest tertile of ASM/weight index was significantly higher compared to those in the other two tertiles after adjustment for the above confounders. Conclusions: This is the first study to establish an independent association between low muscle mass and NAFLD/NASH in overweight/obese youths. Considering the worldwide increase of pediatric obesity, measurements of muscle mass may serve as useful method of identifying among obese children those at high metabolic risk who may need intensive lifestyle interventions to prevent NAFLD and its progression.

[Impact of Sarcopenia on the Risk of Erosive Esophagitis]

Background/Aims

An association between obesity and erosive esophagitis has been reported, but the effects of sarcopenia and obesity on erosive esophagitis are unknown. This study examined the relationship between obesity, sarcopenia, sarcopenic obesity, and erosive esophagitis in a large population of asymptomatic men and women.

Methods

This study analyzed 32,762 subjects who underwent a comprehensive health check-up, which included upper gastrointestinal endoscopy, from August 2006 to December 2011 by a cross-sectional study. Sarcopenia was defined as a decrease in the appendicular skeletal muscle mass (ASM)/body weight value of two SD or more below the normal means for a younger reference group.

Results

The study was carried out on four groups according to obesity and sarcopenic status: normal, obesity, sarcopenic, and sarcopenic obese group. In a multivariable model, the risk of erosive esophagitis was higher in the obese (adjusted OR [aOR] 1.35, 95% CI 1.22-1.49), sarcopenic (aOR 2.12, 95% CI 1.40-3.19), and sarcopenic obese groups (aOR 1.54, 95% CI 1.27-1.87) than in the normal group. The risk of erosive esophagitis was higher in the sarcopenic and sarcopenic obese groups than the obese group; the ORs were 1.63 (95% CI 1.08-2.47) and 1.22 (95% CI 1.01-1.46), respectively. In dose-response analysis, increasing sarcopenia severity showed a positive and graded relationship with the overall, Los Angeles (LA)-B or higher grade, and LA-C erosive esophagitis.

Conclusions

This study suggests that sarcopenia is strongly and progressively associated with erosive esophagitis.

Sarcopenia in nonalcoholic fatty liver disease: new challenges for clinical practice

Introduction: Sarcopenia is increasingly recognized in patients with nonalcoholic liver disease (NAFLD). Initially recognized as a consequence of advanced liver disease, there is now emerging evidence that sarcopenia may be a novel risk factor for the development of NAFLD, with a role in fibrosis and disease progression.Areas covered: This review examines the epidemiology, pathogenesis, and complex interplay between NAFLD and sarcopenia. Furthermore, the authors discuss the challenges with diagnosis of sarcopenia in the clinic and the evidence-based management of sarcopenia in patients with NAFLD. A MEDLINE and PubMed search was undertaken using the terms; 'sarcopenia,' 'frailty,' 'muscle,' 'obesity,' 'non-alcoholic fatty liver disease,' 'non-alcoholic steatohepatitis', and 'cirrhosis' up to 31 September 2019.Expert opinion: Sarcopenia may be masked by the co-existence of morbid obesity, which is most notable in patients with NAFLD. Sarcopenia is a key indicator of adverse outcomes in patients with cirrhosis, such as hepatic decompensation, poor quality of life and premature mortality. Patients with NAFLD and advanced fibrosis/cirrhosis should undergo anthropometric measures (handgrip strength), dry body mass index, and measures of physical frailty (including muscle function, not just mass) to enable targeted early interventions of nutrition (low fat, 1.5 g/kg/day protein intake, 2-3 hourly food intake) and exercise (combined resistance and aerobic).

Creatinine to Body Weight Ratio Is Associated with Incident Diabetes: Population-Based Cohort Study

We investigated the association between creatinine to body weight (Cre/BW) ratio and incident diabetes. In this cohort study, 9659 men and 7417 women were follow up mean (SD) 5.6 (3.5) years and 5.4 (3.4) years, respectively. For men, tertile 1 (T1; n = 3176), Cre/BW < 0.01275; tertile 2 (T2; n = 3258), 0.01275 ≤ Cre/BW < 0.0148; and tertile 3 (T3; n = 3225), Cre/BW ≥ 0.0148; and for women, T1 (n = 2437), Cre/BMI < 0.0118; T2 (n = 2516), 0.0118 ≤ Cre/BMI < 0.014; and T3 (n = 2477), Cre/BMI ≥ 0.014. Among them, 362 men and 102 women developed diabetes. The hazard ratios (HRs) of incident diabetes in the T2 group was 0.56 (95% CI 0.44–0.71, p < 0.001) in men and 0.61 (0.38–0.99, p = 0.045) in women and in the T3 group was 0.42 (0.32–0.54, p < 0.001) in men and 0.55 (0.34–0.89, p = 0.014) in women after adjusting for covariates, compared with the T1 group. Moreover, Δ0.001 incremental of Cre/BW is negatively associated with incident diabetes (adjusted HR 0.84, 95% CI 0.80–0.88, p < 0.001 for men and 0.88, 0.81–0.96, p = 0.003 for women). In conclusion, Cre/BW ratio is inversely related to incident diabetes. Checking Cre/BW ratios may predict future diabetes risks.

Berberine Down-Regulated Myostatin Expression and Facilitated Metabolism via Smad Pathway in Insulin Resistant Mice

OBJECTIVE

To explore the effect of berberine (BBR) on skeletal muscle mass and metabolism and the possible mechanism.

METHODS

Eight-week-old male C57BL/6 mice were fed with a high-fat diet (HFD) for 8 weeks to establish the insulin resistance obesity model. Then, mice were randomly divided into two groups (normal chow diet (NCD) and HFD), while NCD and HFD were further classified into two groups respectively, which were NCD+CS (Carmellose Sodium), NCD+BBR, HFD+CS and HFD+BBR. After the BBR intervention, insulin tolerance test (ITT) and glucose tolerance test (GTT) were carried out. Metabolic parameters and inflammatory biomarkers were detected. Various parts of adipose tissue and gastrocnemius were separated and measured. The gastrocnemius muscle was selected for tissue staining. The mRNA expression of myostatin (Mstn) was tested by quantitative real-time PCR (RT-PCR). Western blotting was performed to detect the expression of Mstn, phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), small ribonucleoprotein particle protein 2 (Smd2), small ribonucleoprotein particle protein 3 (Smd3), and small ribonucleoprotein particle protein 4 (Smd4).

RESULTS

Both body weights (P<0.01) and various parts of fat mass (P<0.001) were decreased significantly, while muscle mass was increased in the HFD group after being treated with BBR. Meanwhile, the glucose and lipid metabolic disorders as well as inflammation status were improved. RT-PCR and Western blotting analysis showed that, after being fed with HFD the expression of Mstn mRNA and Mstn were significantly increased, and decreased after being treated with BBR. Western blotting analysis also showed that, compared with the NCD group, the expressions of Smad2, Smad3, and Smad4 were all increased in the HFD group, but after being treated with BBR, the expressions of Smad3 and Smad4 were decreased.

CONCLUSION

Our study revealed that BBR could improve metabolic disorders and inflammation status, decrease Mstn expression, and increase skeletal muscle mass, which was associated with the Smad pathway.

Relationship between relative skeletal muscle mass and nonalcoholic fatty liver disease: a systematic review and meta-analysis

BACKGROUND AND AIM

Nonalcoholic fatty liver disease (NAFLD) has gradually become one of the most common chronic liver diseases in the world. More and more evidence shows that low skeletal muscle mass index (SMI) may play a role in the development of NAFLD. Our aim was to quantify the association between SMI, sarcopenia and the presence and severity of NAFLD.

METHODS

We systematically searched English relevant studies from PubMed, Embase, the Web of Science and the Cochrane Library updated to December 20th, 2018. Studies in which SMI was compared between NAFLD cases and controls were included. So were studies concerning the odds ratio (OR) of NAFLD, non-alcoholic steatohepatitis (NASH) and significant fibrosis in sarcopenia patients. Pooled weighted mean differences and ORs were calculated.

RESULTS

Of the 1331 retrieved studies, 19 articles were included. SMI level in NAFLD patients was 1.77 (95% CI 1.15, 2.39) lower than that in normal controls. We also found a significantly higher occurrence risk of NAFLD (OR = 1.33, 95% CI 1.20 to 1.48), NASH (OR = 2.42, 95% CI 1.27 to 3.57) and NAFLD-related significant fibrosis (OR = 1.56, 95% CI 1.34, 1.78) in sarcopenia subjects.

CONCLUSIONS

SMI level in patients with NAFLD was lower than healthy people, and patients with sarcopenia have higher occurrence risk of NAFLD, as well as its advanced stages including NASH or NAFLD-related significant fibrosis. Further well-designed prospective studies are required to strengthen the arguments.

Sarcopenia assessed using bioimpedance analysis is associated independently with significant liver fibrosis in patients with chronic liver diseases

AIM

Sarcopenia is common in patients with advanced fibrosis or cirrhosis. We investigated the correlation between sarcopenia and other clinical variables, in particular, significant liver fibrosis in patients with chronic liver diseases (CLDs).

PATIENTS AND METHODS

Patients with CLDs who underwent transient elastography (TE) and bioelectrical impedance analysis between 2015 and 2017 were retrospectively recruited. The sarcopenia index (SI) was calculated as follows: SI = total appendicular skeletal muscle mass (kg)/ body mass index (BMI) (kg/m). Sarcopenia was defined as SI less than 0.789 for men and less than 0.521 for women. Significant liver fibrosis and fatty liver were defined using TE liver stiffness value more than 7 kPa and controlled attenuation parameter more than 250 dB/m, respectively.

RESULTS

Of 2168 patients recruited, 218 (10.1%) had sarcopenia. Age, BMI, diabetes, hypertension, fasting glucose, aspartate aminotransferase, and liver stiffness value were correlated positively with sarcopenia (all P < 0.05), whereas male sex, viral etiology, obesity (BMI > 25 kg/m), total bilirubin, and serum albumin were correlated negatively with sarcopenia (all P < 0.05). On multivariate analysis, TE-defined significant liver fibrosis was associated independently with sarcopenia (odds ratio = 1.597; 95% confidence interval: 1.174-2.172; P = 0.003), together with age, male sex, viral etiology, and TE-defined fatty liver (all P < 0.05). Among the subgroups with ultrasonography-defined nonalcoholic fatty liver disease (n = 957), sarcopenia was also associated independently with TE-defined significant liver fibrosis (odds ratio = 1.887; 95% confidence interval: 1.261-2.823; P < 0.001).

CONCLUSION

Sarcopenia is associated independently with significant liver fibrosis in patients with CLDs. Further studies are required to determine whether interventions to improve muscle mass can improve liver fibrosis.

Impact of intracellular toxic advanced glycation end-products (TAGE) on murine myoblast cell death

BACKGROUND

Sarcopenia is a progressive condition that is characterized by decreases in skeletal muscle mass and function. Although sarcopenia is associated with lifestyle-related diseases (LSRD), the mechanisms underlying cell death in myoblasts, which differentiate to myotubes, remain unclear. We previously designated glyceraldehyde (an intermediate of glucose/fructose metabolism)-derived advanced glycation end-products (AGEs) as toxic AGEs (TAGE) because of their cytotoxicity and involvement in LSRD, and hypothesized that TAGE contribute to cell death in myoblasts.

METHODS

C2C12 cells, which are murine myoblasts, were treated with 0, 0.5, 1, 1.5, and 2 mM glyceraldehyde for 24 h. Cell viability and intracellular TAGE were then assessed using 5-[2,4,-bis(sodioxysulfonyl)phenyl]-3-(2-methoxy-4-nitrophenyl)-2-(4-nitrophenyl)-2H-tetrazole-3-ium (WST-8) and slot blot assays. Cells were pretreated with 8 mM aminoguanidine, an inhibitor of AGE production, for 2 h, followed by 0, 1.5, and 2 mM glyceraldehyde for 24 h. Cell viability and intracellular TAGE levels were then assessed. Serum TAGE levels in STAM mice, in which there were four stages (no steatosis, simple steatosis, steatohepatitis, and fibrosis), were measured using a competitive enzyme-linked immunosorbent assay. Results were expressed as TAGE units (U) per milliliter of serum, with 1 U corresponding to 1.0 μg of glyceraldehyde-derived AGE-bovine serum albumin (BSA) (TAGE-BSA). The viability of cells treated with 20, 50, and 100 μg/mL non-glycated BSA and TAGE-BSA for 24 h was assessed using the WST-8 assay.

RESULTS

In C2C12 cells treated with 1.5 and 2 mM glyceraldehyde, cell viability decreased to 47.7% (p = 0.0021) and 5.0% (p = 0.0001) and intracellular TAGE levels increased to 6.0 and 15.9 μg/mg protein, respectively. Changes in cell viability and TAGE production were completely inhibited by 8 mM aminoguanidine. Serum TAGE levels at the steatohepatitis and fibrosis stages were 10.51 ± 1.16 and 10.44 ± 0.95 U/mL, respectively, and were higher than those at the no steatosis stage (7.27 ± 0.18 U/mL). Cell death was not induced by 20 or 50 μg/mL TAGE-BSA. The viabilities of C2C12 cells treated with 100 μg/mL non-glycated BSA and TAGE-BSA were 105.0% (p = 0.2890) and 85.3% (p = 0.0217), respectively.

CONCLUSION

Intracellular TAGE strongly induced cell death in C2C12 cells and may also induce myoblast cell death in LSRD model mice.

Reduction of Fat to Muscle Mass Ratio Is Associated with Improvement of Liver Stiffness in Diabetic Patients with Non-Alcoholic Fatty Liver Disease

Body weight reduction leads to improvement of nonalcoholic fatty liver disease (NAFLD), but the contributions of body composition modification on its improvement have not been clarified yet. We performed a retrospective cohort study in a Japanese university hospital to clarify the effect of body fat reduction on the improvement of hepatic stiffness as well as hepatic steatosis. The skeletal muscle mass index (SMI, kg/m²), fat to muscle mass ratio, and the change in fat to muscle mass ratio after 1 year from baseline were calculated. Controlled attenuation parameter (CAP, dB/m) and liver stiffness measurement (LSM, kPa) were evaluated by elastography. Primary outcome was set as the association of the change of fat to muscle mass ratio after 1 year from baseline with the change of liver stiffness measurement. One hundred and seventeen patients (59 men and 58 women) completed the study. The average age was 63.5 years, and baseline CAP and LSM were 273.4 ± 53.5 dB/m and 6.3 ± 3.4 kPa, respectively. After 1 year, body mass index (BMI), SMI, and LSM decreased. Multiple regression analyses demonstrated that change in fat to muscle mass ratio was associated with the change in CAP (ß = 0.38, p < 0.001) or LSM (ß = 0.21, p = 0.026). The reduction of fat to muscle mass ratio was associated with improvement in liver stiffness, but the reduction of BMI was not.

Sarcopenia and fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease which may progress to non-alcoholic steatohepatitis. The prevalence of sarcopenia, which is the loss of muscle mass and strength, is increasing in the aging society. Recent studies reported the relationship between NAFLD and sarcopenia. The skeletal muscle is the primary organ for glucose disposal. Loss of muscle mass can cause insulin resistance, which is an important risk factor for NAFLD. Moreover, obesity, chronic low-grade inflammation, vitamin D deficiency, physical inactivity, hepatokines, and myokines might be involved in the pathophysiologic mechanism of sarcopenia and NAFLD. Although most of the previous studies have demonstrated the positive correlation between sarcopenia and NAFLD, the difference in diagnostic methods of sarcopenia and NAFLD leads to difficulties in interpretation and application. This review discusses the concept and diagnosis of sarcopenia and NAFLD, common pathophysiology, and clinical studies linking sarcopenia to NAFLD. The presentation of the association between sarcopenia and NAFLD may provide an opportunity to prevent the deterioration of fatty liver disease.

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

BACKGROUND & AIMS

Myostatin is mainly expressed in skeletal muscle, where it negatively regulates trophism. This myokine is implicated in the pathophysiology of nonalcoholic steatohepatitis, an emerging cause of liver fibrosis. In this study we explored the effects of myostatin on the biology of hepatic stellate cells.

METHODS

The effects of myostatin were assessed both in LX-2 and in human primary stellate cells. Cell migration was determined in Boyden chambers. Activation of intracellular pathways was evaluated by Western blotting. Procollagen type 1 secretion was measured by enzyme immunoassay. The role of c-Jun N-terminal kinase was assessed by pharmacologic and genetic inhibition.

RESULTS

Activin receptor-2B was up-regulated in livers of mice with experimental fibrosis, and detectable in human stellate cells. Serum myostatin levels increased in a model of acute liver injury. Myostatin reduced HSC proliferation, induced cell migration, and increased expression of procollagen type1, tissue inhibitor of metalloproteinase-1, and transforming growth factor-β1. Myostatin activated different signaling pathways, including c-Jun N-terminal kinase and Smad3. Genetic and/or pharmacologic inhibition of c-Jun N-terminal kinase activity significantly reduced cell migration and procollagen secretion in response to myostatin.

CONCLUSIONS

Activation of activin receptor-2B by myostatin modulates the fibrogenic phenotype of human stellate cells, indicating that a myokine may be implicated in the pathogenesis of hepatic fibrosis.

Associations between sarcopenia and nonalcoholic fatty liver disease and advanced fibrosis in the USA

BACKGROUND AND AIM

Nonalcoholic fatty liver disease (NAFLD) may be associated with sarcopenia. This study aims to determine whether sarcopenia is independently associated with NAFLD and advanced fibrosis.

PARTICIPANTS AND METHODS

Cross-sectional data from 11 325 participants in the third National Health and Nutrition Examination Survey were analyzed. NAFLD was defined as the presence of hepatic steatosis from the ultrasound. Sarcopenia was defined as the skeletal muscle index.

RESULTS

NAFLD was more common in participants with sarcopenia than in those without (46.7 vs. 27.5%). Univariate analysis showed that sarcopenia was associated with NAFLD [odds ratio (OR): 2.31; 95% confidence interval (CI): 2.01-2.64], which remained significant after adjustment for age, sex, ethnicity, metabolic risk factors (OR: 1.24; 95% CI: 1.03-1.48). This finding persisted after adjustment for C-reactive protein as a marker of chronic inflammation. NAFLD-associated advanced fibrosis was more common in participants with sarcopenia than in those without (7.8 vs. 1.6%). Sarcopenia was associated with NAFLD-associated advanced fibrosis independent of metabolic risk factors (OR: 1.79; 95% CI: 1.18-2.72).

CONCLUSION

Sarcopenia was independently associated with increased odds of NAFLD and NAFLD-associated advanced fibrosis independent of well-defined risk factors. Interventions to strengthen muscle mass may reduce the burden of NAFLD and advanced fibrosis.

Association of low skeletal muscle mass with advanced liver fibrosis in patients with non-alcoholic fatty liver disease

BACKGROUND AND AIM

Although low skeletal muscle mass (LSMM) is known to increase the risk of non-alcoholic fatty liver disease (NAFLD), limited reports have described the relationship between LSMM and advanced fibrosis. Here, we investigated the association between LSMM and advanced liver fibrosis in NAFLD patients.

METHODS

Fatty liver was diagnosed using ultrasound, and appendicular skeletal muscle mass (ASM) was measured using bioelectrical impedance analysis. LSMM was defined in two ways: ASM/body weight percentage (LSMM-BW) and ASM/body mass index. Liver fibrosis stage was assessed by two models, the NAFLD fibrosis score and the Fibrosis-4 index, which determined low and high cutoff values (COVs).

RESULTS

Of 10 711 NAFLD patients, 615 were diagnosed with LSMM-BW. LSMM patients were older (47.6 vs 52.5 years, P = 0.001) and had higher body mass index values (23.6 vs 29.1 kg/m² , P < 0.001) and waist circumferences (80.1 vs 93.3 cm, P < 0.001) than non-LSMM patients. LSMM was an independent risk factor for advanced fibrosis assessed by a low COV for the Fibrosis-4 index regardless of its classification (adjusted for metabolic and lipid profiles and sex, odds ratio [OR], 1.27-2.01; all P < 0.05). LSMM was an independent risk factor for advanced fibrosis assessed by both COVs of NAFLD fibrosis score (adjusted for obesity, hypertension, lipid profile, and sex; OR, 1.64-2.01, P < 0.01 in the low COV group; OR, 2.68-3.12, P = 0.002 in the high COV group).

CONCLUSIONS

Low skeletal muscle mass is associated with advanced fibrosis in NAFLD patients independent of metabolic risk factors.

The PNPLA3 rs738409 C>G variant influences the association between low skeletal muscle mass and NAFLD: the Shanghai Changfeng Study

BACKGROUND

Age-related skeletal muscle loss and patatin-like phospholipase domain-containing 3 (PNPLA3) polymorphisms are both associated with increased liver steatosis and fibrosis in the absence of obesity.

AIM

To investigate the influence of PNPLA3 polymorphism on the relationship between skeletal muscle loss and non-alcoholic fatty liver disease (NAFLD).

METHODS

Liver fat content was measured using a quantitative ultrasound method, and liver fibrosis was assessed by NAFLD fibrosis, BARD and FIB-4 scores in 3969 Chinese adults. The degree of sarcopenia was measured by weight-adjusted appendicular skeletal muscle mass (ASM% = appendicular skeletal muscle mass(kg)/body weight(kg)  100%).

RESULTS

The NAFLD proportion increased from 19.9% to 41.2% in men and 26.3% to 42.3% in women with decreasing ASM% quartiles (P < 0.001). Low ASM% was inversely associated with NAFLD in PNPLA3 CC (odds ratio [OR]: men, 0.735 [0.610-0.885] and women, 0.812 [0.718-0.918], both P = 0.001) and CG (OR: men, 0.673 [0.573-0.790] and women, 0.798 [0.713-0.893], both P < 0.001) but not GG genotype carriers. The association remained significant after adjustment for age, cigarette smoking, fat mass, interaction between fat mass and ASM%, obesity, diabetes and all components of metabolic syndrome. Subgroup analyses found that PNPLA3 GG gene variant did not increase the risk for NAFLD in individuals with low ASM% regardless of obesity status. Low ASM% also increased risk for liver fibrosis (all P < 0.05), which became insignificant after multiple adjustments.

CONCLUSIONS

Low ASM% is associated with NAFLD and liver fibrosis. Dissociation of sarcopenia and NAFLD was found in PNPLA3 GG genotype carriers. A stratification based on PNPLA3 genotypes might facilitate personalised treatment for NAFLD.

Non-alcoholic fatty liver disease in lean individuals

Non-alcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease, encompassing a spectrum from non-alcoholic fatty liver to non-alcoholic steatohepatitis, which can progress to cirrhosis. It has recently been recognised that NAFLD also occurs in individuals who are not obese, especially in Asian populations. In these patients, NAFLD manifests at lower overall body mass index thresholds in the presence of increased visceral adipose tissue. Currently, the principles of clinical management are similar to those in obese individuals, although, in specific regions and clinical situations, unique aetiologies of NAFLD must be treated specifically.

Body Composition and Genetic Lipodystrophy Risk Score Associate With Nonalcoholic Fatty Liver Disease and Liver Fibrosis

Up to 25% of patients with nonalcoholic fatty liver disease (NAFLD) are not obese but may have a fat or muscle composition that predisposes them to NAFLD. Our aim was to determine whether body composition parameters associate with NAFLD and to identify genetic contributors to this association. This study included two cohorts. The first included 2,249 participants from the Framingham Heart Study who underwent a computed tomography scan to evaluate hepatic steatosis, dual-energy x-ray absorptiometry testing to assess body composition, and clinical examination. Body composition parameters were normalized to total body weight. A subset of participants underwent genotyping with an Affymetrix 550K single-nucleotide polymorphism array. The second cohort, Michigan Genomics Initiative, included 19,239 individuals with genotyping on the Illumina HumanCoreExome v.12.1 array and full electronic health record data. Using sex-stratified multivariable linear regression, greater central body fat associated with increased hepatic steatosis while greater lower extremity body fat associated with decreased hepatic steatosis. Greater appendicular lean mass was associated with decreased hepatic steatosis in men but not in women. A polygenic risk score for lipodystrophy (regional or global loss of adipose tissue) was associated with increased hepatic steatosis, increased liver fibrosis, and decreased lower extremity fat mass. Conclusion: Greater central body fat associated with increased hepatic steatosis, while greater lower extremity body fat and, in men, greater appendicular lean mass were associated with decreased hepatic steatosis. A genetic risk score for lipodystrophy was associated with NAFLD and liver fibrosis. Our results suggest that buffering of excess energy by peripheral fat and muscle may protect against NAFLD and liver fibrosis in the general population.

Extra-hepatic manifestations and complications of nonalcoholic fatty liver disease

This review article aims to synthesize the evidence regarding nonalcoholic fatty liver disease (NAFLD) as a systemic disorder. We critically discuss the metabolic syndrome and its components; the cardiovascular and the endocrine system; chronic respiratory disorders; the musculoskeletal system; the skin; and extra-hepatic tumors. We conclude that, while some of these extra-hepatic conditions clearly predispose to the development of secondary forms of NAFLD (typically hypothyroidism-induced NAFLD), others result from pre-existent NAFLD (e.g., certain extra-hepatic tumors) and others (such as Type 2 Diabetes) have, with NAFLD, mutual and bidirectional associations. Analyzed data imply that NAFLD is not merely a hepatic disease. It is also and possibly more importantly, a systemic disorder requiring a special awareness, a multidisciplinary approach and a multidimensional vision.

Nonalcoholic Fatty Liver Disease in The Rotterdam Study: About Muscle Mass, Sarcopenia, Fat Mass, and Fat Distribution

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver disease worldwide. Obesity is a major risk factor for NAFLD and recently, low skeletal muscle mass emerged as additional risk factor for NAFLD. However, the different contributions of body mass index (BMI) to the risk of NAFLD are not yet well-known. We therefore studied body composition and muscle function with NAFLD in an elderly population-based study. Participants of European descent underwent dual-energy X-ray absorptiometry (DXA) and hepatic ultrasonography. NAFLD was defined as liver steatosis in absence of secondary causes for steatosis. Skeletal muscle index (SMI) was defined as appendicular lean mass/height² and (pre)sarcopenia was defined using the European Working Group on Sarcopenia in Older People (EWGSOP) consensus guidelines. All analyses were stratified by sex and BMI (cut point: 25 kg/m² ) and adjusted for age, weight, height, homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides, and android-fat-to-gynoid-fat ratio (AGR). We included 4609 participants, of whom 1623 had NAFLD (n = 161 normal-weight and n = 1462 overweight). Presarcopenia and sarcopenia prevalence was low (5.9% and 4.5%, respectively) and both were not associated with NAFLD. SMI was associated with less NAFLD in normal-weight women (OR, 0.48; 95% CI, 0.29 to 0.80). A similar association for SMI and NAFLD was seen in normal-weight men, but significance dissipated after adjustment for AGR (OR, 0.63; 95% CI, 0.39 to 1.02). Generally, fat mass was a better predictor for NAFLD than lean mass. In particular, android fat mass was associated with all NAFLD subgroups (OR from 1.77 in overweight men to 8.34 in normal-weight women, p_max = 0.001), whereas substitution of gynoid fat mass for other body components had a significant protective association with NAFLD in every subgroup, but normal-weight men. Likewise, AGR was the best performing predictor for NAFLD prevalence (OR from 1.97 in normal-weight men to 4.81 in normal-weight women, p_max < 0.001). In conclusion, both high fat mass and low SMI were associated with normal-weight NAFLD. However, fat distribution (as assessed by AGR) could best predict NAFLD prevalence. © 2019 American Society for Bone and Mineral Research.

Sarcopenia Is Significantly Associated with Presence and Severity of Nonalcoholic Fatty Liver Disease

Background

The association between nonalcoholic fatty liver disease (NAFLD) and sarcopenia has been suggested. We investigated the association between sarcopenia and NAFLD independent of visceral adiposity and searched for the clinical characteristics that affect this association.

Methods

We performed a retrospective study including of 5,989 subjects (mean age, 53.2 years; men, 57.3%) who underwent bioelectrical impedance analysis (BIA) and abdominal ultrasonography in 2012. The appendicular skeletal muscle mass (ASM) was assessed by BIA method. Sarcopenia was defined as ASM/weight (ASM%) <2 standard deviation of the mean for healthy young reference population. NAFLD was diagnosed by ultrasonography.

Results

The prevalence of sarcopenia was 5.3%. The prevalence of NAFLD was significantly higher in subjects with sarcopenia than in those without (69.5% vs. 36.5%, P<0.001). After adjusting with age, sex, visceral fat area, hypertension, diabetes, total and low-density lipoprotein cholesterol, subjects with sarcopenia showed significantly high odds of NAFLD (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.02–1.84; P=0.036). Subjects with sarcopenia have more likely severe grade of NAFLD compared to non-sarcopenic group (OR, 1.58; 95% CI, 1.25–2.00; P<0.001). There was significant interaction for effect modification in the association between sarcopenia and NAFLD by age (P of interaction for effect modification, 0.007).

Conclusion

Sarcopenia was significantly associated with the presence and the severity of ultrasonography-graded NAFLD in our study population independent of visceral fatness and other metabolic confounder. Younger age showed greater magnitude of association between sarcopenia and NAFLD.

Nonalcoholic fatty liver disease in the over-60s: Impact of sarcopenia and obesity

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in children and adults of all ethnicities. NAFLD is commonly seen in individuals with metabolic abnormalities, such as obesity and insulin resistance, which are closely associated with sarcopenia. Sarcopenia, defined as low muscle mass and impaired muscle function, is associated with NAFLD and worse outcomes in patients with NAFLD. As the world's elderly population and the prevalence of obesity continues to grow at an unprecedented rate, NAFLD and sarcopenia are projected to increase. Given that there are no approved pharmacologic treatments for NAFLD, it is imperative to gain a better understanding of the disease pathophysiology, to guide treatment options. Recent studies have given new insight into sarcopenic obesity, but there is no consensus on its definition. In this review, we attempt to address the impact of sarcopenia and obesity on NAFLD, especially in the elderly population.

Clinical and pathological features of sarcopenia-related indices in patients with non-alcoholic fatty liver disease

BACKGROUND

Sarcopenia is diagnosed with the skeletal muscle index (SMI) or the sarcopenia index (SI). We previously reported that the ratio of skeletal muscle mass to body fat mass (SF ratio) was a novel index of sarcopenia in patients with non-alcoholic fatty liver disease (NAFLD). The aim of this retrospective study was to evaluate sarcopenia with these indices in patients with NAFLD.

METHODS

One hundred and fifty-six consecutive patients with biopsy-proven NAFLD and alanine aminotransferase (ALT) >40 IU/L were enrolled. Liver function and body composition were evaluated in 121 patients after 12 months. We evaluated the relationship between histological findings, changes in liver function, and the SMI, SI, and SF ratio.

RESULTS

Of the 156 patients enrolled, 13.5% and 26.3% were diagnosed with sarcopenia with the SMI and SI. In patients with hepatic fibrosis stage <2, the SI and the SF ratio were significantly greater than in patients with fibrosis stage ≥2. There was no difference in SMI between groups. In the cohort assessed at baseline and 12 months later, transaminase activity and SMI decreased significantly, and the SF ratio increased over time. A multivariate analysis revealed the presence of the PNPLA3 G allele and an increase in SF ratio (odds ratio, 7.406) as predictive factors of ALT reduction >30% from baseline.

CONCLUSIONS

Due to the high prevalence of obesity, we should consider both skeletal muscle mass and body fat mass in the diagnosis and treatment of NAFLD. The SF ratio could be a useful index in sarcopenic NAFLD.