Presence and Implications of Sarcopenia in Non-alcoholic Steatohepatitis

Exercise and nutrition benefit skeletal muscle: From influence factor and intervention strategy to molecular mechanism

Sarcopenia is a progressive systemic skeletal muscle disease induced by various physiological and pathological factors, including aging, malnutrition, denervation, and cardiovascular diseases, manifesting as the decline of skeletal muscle mass and function. Both exercise and nutrition produce beneficial effects on skeletal muscle growth and are viewed as feasible strategies to prevent sarcopenia. Mechanisms involve regulating blood flow, oxidative stress, inflammation, apoptosis, protein synthesis and degradation, and satellite cell activation through exerkines and gut microbiomes. In this review, we summarized and discussed the latest progress and future development of the above mechanisms for providing a theoretical basis and ideas for the prevention and treatment of sarcopenia.

Approaching the Sarcopenic Patient with Nonalcoholic Steatohepatitis-related Cirrhosis

Sarcopenia is a well-known complication of chronic liver disease (CLD), and it is almost always observed in patients with cirrhosis, at least in those with decompensated disease. Since nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic dysfunction-associated steatotic liver disease (MASLD), is becoming the leading cause of end-stage liver disease, a new scenario characterized by the frequent coexistence of NAFLD, obesity, and sarcopenia is emerging. Although it is not yet resolved whether the bidirectional relationship between sarcopenia and NAFLD subtends causal determinants, it is clear that the interaction of these two conditions is associated with an increased risk of poor outcomes. Notably, during the course of CLD, deregulation of the liver-muscle-adipose tissue axis has been described. Unfortunately, owing to the lack of properly designed studies, specific therapeutic guidelines for patients with sarcopenia in the context of NAFLD-related CLD have not yet been defined. Strategies aimed to induce the loss of fat mass together with the maintenance of lean body mass seem most appropriate. This can be achieved by properly designed diets integrated with specific nutritional supplementations and accompanied by adequate physical exercise. Future studies aiming to add to the knowledge of the correct assessment and approach to sarcopenia in the context of NAFLD-related CLD are eagerly awaited.

GLP-1 receptor agonists in the treatment of diabetic non-alcoholic steatohepatitis patients

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is the most common hepatic disease affecting almost 30% of the world population. Approximately 25% of people with NAFLD develop nonalcoholic steatohepatitis (NASH), the fulminant version of the disease. Diabetes mellitus is present in 22.5% of people with NAFLD and 44.60% of individuals with NASH. This review was undertaken to examine the current contribution of glucagon-like peptide 1 (GLP-1) receptor agonists to the pharmacotherapy of diabetic nonalcoholic steatohepatitis.

AREAS COVERED

The author analyzed the current status of GLP-1 receptor agonists for pharmacotherapy of diabetic NASH. Research data and literature reports were taken from the database and or websites of Diabetes UK, American Diabetes Association, ClinicalTrials.gov, PubMed, and Scopus. The keywords utilized included type 2 diabetes, GLP-1, NASH, NAFLD, and clinical trials.

EXPERT OPINION

Since diabetic NASH is associated with obesity, diabetes mellitus, oxidative stress and inflammation, drugs capable of mitigating all of these conditions simultaneously, are most ideal for the treatment of diabetic NASH. These drugs include (in order of relevance), GLP-1 receptor agonists, GLP-1 and GIP dual receptor agonists, sodium-glucose co-transporter-2 (SGLT2) inhibitors, and pioglitazone. The future, FDA-approved drug for diabetic NASH treatment will likely be GLP-1 agonist, which could be used as monotherapy or in combination with other drugs.

LEARN algorithm: a novel option for predicting non-alcoholic steatohepatitis

Background

There is an unmet need for accurate non-invasive methods to diagnose non-alcoholic steatohepatitis (NASH). Since impedance-based measurements of body composition are simple, repeatable and have a strong association with non-alcoholic fatty liver disease (NAFLD) severity, we aimed to develop a novel and fully automatic machine learning algorithm, consisting of a deep neural network based on impedance-based measurements of body composition to identify NASH [the bioeLectrical impEdance Analysis foR Nash (LEARN) algorithm].

Methods

A total of 1,259 consecutive subjects with suspected NAFLD were screened from six medical centers across China, of which 766 patients with biopsy-proven NAFLD were included in final analysis. These patients were randomly subdivided into the training and validation groups, in a ratio of 4:1. The LEARN algorithm was developed in the training group to identify NASH, and subsequently, tested in the validation group.

Results

The LEARN algorithm utilizing impedance-based measurements of body composition along with age, sex, pre-existing hypertension and diabetes, was able to predict the likelihood of having NASH. This algorithm showed good discriminatory ability for identifying NASH in both the training and validation groups [area under the receiver operating characteristics (AUROC): 0.81, 95% CI: 0.77-0.84 and AUROC: 0.80, 95% CI: 0.73-0.87, respectively]. This algorithm also performed better than serum cytokeratin-18 neoepitope M30 (CK-18 M30) level or other non-invasive NASH scores (including HAIR, ION, NICE) for identifying NASH (P value <0.001). Additionally, the LEARN algorithm performed well in identifying NASH in different patient subgroups, as well as in subjects with partial missing body composition data.

Conclusions

The LEARN algorithm, utilizing simple easily obtained measures, provides a fully automated, simple, non-invasive method for identifying NASH.

SHRSP5/Dmcr rats fed a high-fat and high-cholesterol diet develop disease-induced sarcopenia as nonalcoholic steatohepatitis progresses

BACKGROUND

Secondary sarcopenia develops as a result of a bedridden state and illnesses, such as cachexia, liver disease, and diabetes. However, there is a lack of animal models to investigate the underlying mechanisms and potential treatments for secondary sarcopenia. Recently, secondary sarcopenia has been associated with the prognosis of nonalcoholic steatohepatitis. This study aimed to investigate whether stroke-prone spontaneously hypertensive rat 5 (SHRSP5/Dmcr) which developed severe nonalcoholic steatohepatitis by a high-fat and high-cholesterol (HFC; containing 2% cholic acid) diet is a useful model of secondary sarcopenia.

METHODS

SHRSP5/Dmcr rats were divided into 6 groups fed with a Stroke-Prone (SP: normal chow) or HFC diets for different periods (4, 12, and 20 weeks), and WKY/Izm rats were divided into 2 groups fed an SP or HFC diet. Body weight, food intake, and muscle force were measured weekly for all rats. After the end of the diet period, skeletal muscle strength evoked by electrical stimulation was recorded, blood was collected, and organ weight was measured. The sera were used for biochemical analysis and the organs were used for histopathological analysis.

RESULTS

SHRSP5/Dmcr rats fed an HFC diet developed nonalcoholic steatohepatitis, and their skeletal muscles, especially fast muscles, showed atrophy, indicating that muscle atrophy is aggravated by the progression of nonalcoholic steatohepatitis. In contrast, WKY/Izm rats fed an HFC diet did not exhibit sarcopenia.

CONCLUSIONS

This study suggests that SHRSP5/Dmcr rats could be a useful novel model for investigate the mechanism of secondary sarcopenia disorder associated with nonalcoholic steatohepatitis.

Gender difference in association between low muscle mass and risk of non-alcoholic fatty liver disease among Chinese adults with visceral obesity

Background and aims

Although the association between low muscle mass and the risk of non-alcoholic fatty liver disease is well-known, it has not been explored in viscerally obese populations by gender. Besides, whether low muscle mass still increases the NAFLD risk in subjects with visceral obesity, independent of obesity, is still unknown. The aim of this study was to explore the gender-specific association between low muscle mass and the risk of non-alcoholic fatty liver disease (NAFLD) in subjects with visceral obesity.

Methods

Overall, 1,114 participants aged 19-89 years were recruited in this retrospective study. Liver disease was diagnosed by hepatic ultrasound. Skeletal muscle mass was estimated by bioimpedance analysis and defined by the appendicular skeletal muscle index (ASMI). Gender-specific differences in the ASMI value were compared between NAFLD and control groups. Restricted cubic spline and multivariate logistic regression were performed to analyze the association (stratified by gender and age) between the ASMI and the risk of NAFLD, respectively.

Results

Middle-aged females (40-60 years) and males (of any age) with NAFLD had a significantly lower ASMI compared with controls (P-value < 0.05). An inverse linear association was found between the ASMI and risk of NAFLD (all P _{fornon-linearity} > 0.05). Lower quartiles of the ASMI conferred independent risk of NAFLD compared to higher quartiles (all P for trend < 0.001). Low muscle mass conferred a higher risk of NAFLD in middle-aged females (adjusted odds ratio = 2.43, 95% confidence interval: 1.19-4.95) and males [18-39 years: 3.76 (1.79-7.91); 40-60 years: 4.50 (2.16-9.39); and >60 years: 4.10 (1.13-14.84)]. Besides, Low muscle mass and low muscle mass with obesity increase the risk of developing NAFLD, independent of obesity.

Conclusion

Among those with visceral obesity, low muscle mass increased the risk of NAFLD in males of any age, and middle-aged females, this may be explained by the postmenopausal decline in estrogen.

Suppressed serological vitamin A in patients with liver cirrhosis is associated with impaired liver function and clinical detoriation

BACKGROUND

The liver is of critical importance for the homeostasis of metabolic and immunomodulatory properties as well as the storage of vitamins, especially vitamin A. In this prospective analysis, the incidence of serological vitamin A deficiency and the association with disease severity as well as clinical complications in patients with liver cirrhosis were investigated.

METHOD

From May 2017 to May 2018, 159 patients with primarily alcohol-associated and non-alcoholic steatohepatitis (NASH)-associated preexisting liver cirrhosis were prospectively enrolled and vitamin A status was collected. Clinical complications and infections were followed and recorded over a period of 1-year follow-up. Selected findings were validated in an independent cohort of 44 patients.

RESULTS

At study inclusion, 77% of patients showed decreased serological vitamin A. Suppressed vitamin A was more common in alcoholic (52 vs. 8%) and NASH-associated liver cirrhosis (16 vs. 9%) than in viral-associated liver cirrhosis. MELD score as well as Child-Pugh score were significantly associated with suppressed vitamin A ( P  < 0.001). The association between the degree of vitamin A suppression and liver function was confirmed in univariate and multivariate regression analysis. After 1 year of follow-up, 57 patients died and 21 patients received a liver transplant. In addition, low vitamin A levels were more commonly observed in patients with severe ascites ( P  = 0.001), hepatic encephalopathy ( P  = 0.002) and hepatorenal syndromes ( P  = 0.008). In addition, patients with reduced vitamin A showed an increased incidence of infections ( P  = 0.02), especially respiratory infections ( P  = 0.04).

CONCLUSION

Suppressed serological Vitamin A is common in patients with liver cirrhosis and is associated with liver function. Clinical complications and infections are more frequent in patients with liver cirrhosis and vitamin A suppression.

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

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

Metabolic Syndrome and Sarcopenia

Skeletal muscle is a major organ of insulin-induced glucose metabolism. In addition, loss of muscle mass is closely linked to insulin resistance (IR) and metabolic syndrome (Met-S). Skeletal muscle loss and accumulation of intramuscular fat are associated with a variety of pathologies through a combination of factors, including oxidative stress, inflammatory cytokines, mitochondrial dysfunction, IR, and inactivity. Sarcopenia, defined by a loss of muscle mass and a decline in muscle quality and muscle function, is common in the elderly and is also often seen in patients with acute or chronic muscle-wasting diseases. The relationship between Met-S and sarcopenia has been attracting a great deal of attention these days. Persistent inflammation, fat deposition, and IR are thought to play a complex role in the association between Met-S and sarcopenia. Met-S and sarcopenia adversely affect QOL and contribute to increased frailty, weakness, dependence, and morbidity and mortality. Patients with Met-S and sarcopenia at the same time have a higher risk of several adverse health events than those with either Met-S or sarcopenia. Met-S can also be associated with sarcopenic obesity. In this review, the relationship between Met-S and sarcopenia will be outlined from the viewpoints of molecular mechanism and clinical impact.