Decreased muscle mass in nonalcoholic fatty liver disease: new evidence of a link between growth hormone and fatty liver disease?

Low Muscle Strength as Risk Factor for Non-Alcoholic Fatty Liver Disease in Different Metabolic Conditions

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) recently became a leading liver disease that threatens health worldwide. Low muscle strength, obesity, insulin resistance, and metabolic syndrome are recognized key factors for NAFLD. However, the impact of low muscle strength itself in different metabolic conditions has not been widely studied.

METHODS

A cross-sectional analysis was performed of a sample of 5,427 participants from the 2019 Korea National Health and Nutrition Examination Survey. Relative handgrip strength (rHGS, defined as handgrip strength/body mass index) was used to assess muscle strength. The cut-off values for a low rHGS were 1.405 for men and 0.850 for women. NAFLD was diagnosed if the Hepatic Steatosis Index was >36. Participants were stratified according to insulin resistance, metabolic syndrome, and central obesity for the subgroup analyses.

RESULTS

Complex sample multivariate logistic regression analysis revealed a significant association between low muscle strength and NAFLD after the adjustment for other confounders (odds ratio [OR], 1.92; P<0.001). In the insulin resistance, metabolic syndrome, and central obesity subgroups, a significant association between low muscle strength and NAFLD remained (OR, 1.66-4.19 depending on subgroup; all P<0.05), whereas it did not in the no central obesity group.

CONCLUSION

This study demonstrated that low muscle strength is correlated with a risk of NAFLD. This relationship was independent of insulin resistance and metabolic syndrome but was dependent on the presence of central obesity.

Multi-omics analysis reveals the toxic mechanism of ammonia-enhanced Microcystis aeruginosa exposure causing liver fat deposition and muscle nutrient loss in zebrafish

Microcystis aeruginosa and ammonia pollution are two important environmental stress factors in water eutrophication. Herein, we simulated environmental conditions to investigate the effects of chronic exposure (single and combined) to M. aeruginosa and total ammonia nitrogen (TAN) on lipid metabolism and muscle quality in zebrafish. Our results showed that M. aeruginosa and TAN significantly induced lipid deposition and tissue damage in the liver of zebrafish. Liver transcriptomic analysis revealed that M. aeruginosa and TAN disrupted the balance in lipid synthesis, decomposition, and transport, ultimately leading to hepatic lipid accumulation. Moreover, exposure to M. aeruginosa or TAN alone resulted in decreased crude protein content and increased lipid content in muscle, as well as disrupted muscle fatty acid composition. Metabolomic analysis of muscle revealed significant alterations in metabolites such as glycerolipids, glycerophospholipids and fatty acids. The co-exposure of M. aeruginosa and TAN had a more significant effect on liver lipid dysfunction and muscle quality deterioration in zebrafish. These findings provide valuable insights into the potential risks and hazards of M. aeruginosa and TAN in eutrophic water bodies subject to Microcystis blooms, and can help inform effective strategies for monitoring and managing these toxins in aquatic ecosystems.

Nonalcoholic Fatty Liver Disease and Endocrine Axes—A Scoping Review

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease. NAFLD often occurs associated with endocrinopathies. Evidence suggests that endocrine dysfunction may play an important role in NAFLD development, progression, and severity. Our work aimed to explore and summarize the crosstalk between the liver and different endocrine organs, their hormones, and dysfunctions. For instance, our results show that hyperprolactinemia, hypercortisolemia, and polycystic ovary syndrome seem to worsen NAFLD’s pathway. Hypothyroidism and low growth hormone levels also may contribute to NAFLD’s progression, and a bidirectional association between hypercortisolism and hypogonadism and the NAFLD pathway looks likely, given the current evidence. Therefore, we concluded that it appears likely that there is a link between several endocrine disorders and NAFLD other than the typically known type 2 diabetes mellitus and metabolic syndrome (MS). Nevertheless, there is controversial and insufficient evidence in this area of knowledge.

Dietary polystyrene nanoplastics exposure alters liver lipid metabolism and muscle nutritional quality in carnivorous marine fish large yellow croaker (Larimichthys crocea)

Nanoplastics (NPs) cause various adverse effects on marine fish. However, effects of dietary NPs exposure on liver lipid metabolism and muscle nutritional quality of carnivorous marine fish are not fully understood. In this study, a 21-day feeding test was conducted to simulate the food chain transfer of polystyrene nanoplastics (PS NPs) and then evaluate effects of different dietary PS NPs levels on the survival, growth performance, liver lipid metabolism, and muscle nutritional quality of large yellow croaker Larimichthys crocea. Results indicated that the survival and growth of large yellow croaker decreased with the increase of PS NPs levels. Moreover, PS NPs induced excessive liver lipid accumulation by down-regulating the expression of lipolysis-related genes and inhibiting the AMPK-PPARα signaling pathway. In vitro, PS NPs could be accumulated in hepatocytes, reduce cell viability, and disrupt lipid metabolism of hepatocytes. Also, we found for the first time that PS NPs altered fatty acid composition and texture of fish muscle by enhancing oxidative stress and disrupting lipid metabolism. Overall, this study indicated that PS NPs induced liver lipid deposition by inhibiting lipolysis, and demonstrated that PS NPs altered the nutritional quality of fish, which might cause potential health effects for human consumers.

The effect of liver enzymes on body composition: A Mendelian randomization study

Background

Higher alanine transaminase (ALT), indicating poor liver function, is positively associated with diabetes but inversely associated with body mass index (BMI) in Mendelian randomization (MR) studies, suggesting liver function affects muscle mass. To clarify, we assessed the associations of liver enzymes with muscle and fat mass observationally with two-sample MR as a validation.

Methods

In the population-representative “Children of 1997” birth cohort (n = 3,455), we used multivariable linear regression to assess the adjusted associations of ALT and alkaline phosphatase (ALP) at ~17.5 years with muscle mass and body fat percentage observationally. Genetic variants predicting ALT, ALP and gamma glutamyltransferase (GGT) were applied to fat-free and fat mass in the UK Biobank (n = ~331,000) to obtain unconfounded MR estimates.

Results

Observationally, ALT was positively associated with muscle mass (0.11 kg per IU/L, 95% confidence interval (CI) 0.10 to 0.12) and fat percentage (0.15% per IU/L, 95% CI 0.13 to 0.17). ALP was inversely associated with muscle mass (-0.03 kg per IU/L, 95% CI -0.04 to -0.02) and fat percentage (-0.02% per IU/L, 95% CI -0.03 to -0.01). Using MR, ALT was inversely associated with fat-free mass (-0.41 kg per 100% in concentration, 95% CI -0.64 to -0.19) and fat mass (-0.58 kg per 100% in concentration, 95% CI -0.85 to -0.30). ALP and GGT were unclearly associated with fat-free mass or fat mass.

Conclusion

ALT reducing fat-free mass provides a possible pathway for the positive association of ALT with diabetes and suggests a potential target of intervention.

SARCOPENIA AND SEVERITY OF NON-ALCOHOLIC FATTY LIVER DISEASE

BACKGROUND

Non-alcoholic fatty liver disease is characterized by deposition of lipids in the hepatic parenchyma exceeding 5% of liver weight in the absence of other conditions, such as viral or alcoholic hepatitis and metabolic disease. Non-alcoholic fatty liver disease is the most common form of chronic liver disease in several countries. In addition to liver complications, recent studies have shown a relation between liver fat and sarcopenia.

OBJECTIVE

Determine the association between sarcopenia and the severity of non-alcoholic hepatic steatosis diagnosed by abdominal ultrasonography.

METHODS

A clinical, cross-sectional study was conducted with a sample of male and female adults (18 to 70 years of age) submitted to ultrasonography for the investigation of non-alcoholic hepatic steatosis. Evaluations were also performed for the determination of upper and lower limb muscle strength. Data analysis was performed with the aid of the SPSS 22.0 program and involved ANCOVA and the Bonferroni post hoc test, with P-value <0.05 considered indicative of statistical significance.

RESULTS

One hundred two patients were submitted to abdominal ultrasonography, 57.8% of whom presented some degree of non-alcoholic hepatic steatosis. The presence and degree of fatty liver infiltration were significantly associated with the sarcopenic index, determined by the ratio between upper and lower limb strength and BMI (P=0.009 and post-test P=0.028 for upper limbs; P=0.006 and post-test P=0.013 for lower limbs).

CONCLUSION

In the present study, an association was found between the sarcopenic index and non-alcoholic hepatic steatosis, with an inversely proportional relation between this index and the severity of fatty infiltration. This finding offers further evidence of the metabolic interaction of the liver, adipose tissue and muscle.

Effect of probiotic supplementation in nonalcoholic steatohepatitis patients: PROBILIVER TRIAL protocol

Background

Recently factors in the relationship between gut microbiota, obesity, diabetes and the metabolic syndrome have been suggested in the development and progression of nonalcoholic steatohepatitis (NASH). In this sense, this work aims to evaluate the effects of probiotic supplementation on intestinal microbiota modulation, degree of hepatic steatosis and fibrosis, inflammation, gut permeability, and body composition.

Methods

This double-blind, randomized clinical trial will include adult outpatients with a diagnosis of NASH confirmed by biopsy with or without transient elastography. All patients will undergo a complete anamnesis to investigate their alcohol consumption, previous history, medications, nutritional assessment (dietary intake and body composition), sarcopenia, physical activity level and physical and functional capacity, cardiovascular risk, biochemical parameters for assessment of inflammatory status, lipid profile, hepatic function, gut permeability, and assessment of microbiota. These procedures will be performed at baseline and repeated after 24 weeks (at the end of the study). Through the process of randomization, patients will be allocated to receive treatment A or treatment B. Both patients and researchers involved will be blinded (double-blind study). The intervention consists of treatment with a probiotic mix (Lactobacillus acidophillus + Bifidobacterium lactis + Lactobacillus rhamnosus + Lactobacillus paracasei, 1 x 10⁹ CFU for each) and the placebo which is identical in all its characteristics and packaging. Patients will be instructed to consume two sachets/day during 24 weeks and to report any symptoms or side effects related to the use of the sachets. Adherence control will be carried out through the patient’s notes on a form provided, and also by checking the number of sachets used.

Discussion

The final results of study will be analyzed and disseminated in 2020.

Trial registration

ClinicalTrials.gov, ID: NCT03467282. Registered on 15 March 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3679-7) contains supplementary material, which is available to authorized users.

Emerging awareness on the importance of skeletal muscle in liver diseases: time to dig deeper into mechanisms!

Skeletal muscle is a tissue that represents 30–40% of total body mass in healthy humans and contains up to 75% of total body proteins. It is thus the largest organ in non-obese subjects. The past few years have seen increasing awareness of the prognostic value of appreciating changes in skeletal muscle compartment in various chronic diseases. Hence, a low muscle mass, a low muscle function and muscle fatty infiltration are linked with poor outcomes in many pathological conditions. In particular, an affluent body of evidence links the severity, the complications and mortality of chronic liver disease (CLD) with skeletal muscle depletion. Yet it is still not clear whether low muscle mass is a cause, an aggravating factor, a consequence of the ongoing disease, or an epiphenomenon reflecting general alteration in the critically ill patient. The mechanisms by which the muscle compartment influences disease prognosis are still largely unknown. In addition, whether muscle alterations contribute to liver disease progression is an unanswered question. Here, we first review basic knowledge about muscle compartment to draw a conceptual framework for interpreting skeletal muscle alteration in CLD. We next describe recent literature on muscle wasting in cirrhosis and liver transplantation. We then discuss the implication of skeletal muscle compartment in non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH), focusing on plausible metabolic disruption in muscle compartment that might participate in NAFLD progression. Finally, we discuss shortcomings and challenges we need to address in the near future prior to designate the muscle compartment as a therapeutic target in CLD.

Sarcopenia in patients with non-alcoholic fatty liver disease: is it a clinically significant entity?

Sarcopenia, described as the loss of muscle mass and/or strength, is gaining importance as it can be increasingly related to many chronic diseases. It is also associated with chronic liver disease, and recently it has been more frequently linked to non-alcoholic fatty liver disease (NAFLD) in particular. Both sarcopenia and NAFLD are subject to complex and intermingled pathophysiological processes, of which some are in common. Furthermore, it is presently unclear if sarcopenia directly contributes to NAFLD or vice versa. The mechanisms that are involved may include obesity, insulin resistance, vitamin D deficiency, aging, physical inactivity and certain cytokines. Current clinical evidence is subject to an important heterogeneity in methods and definitions, with additionally also a relative overrepresentation of evidence in Asian ethnicities. Nonetheless, all studies so far point towards the same association between sarcopenia and NAFLD, including an association with NAFLD-severity and NAFLD-related fibrosis. Since the field is in its infancy, clear definitions and further research are needed to aid to improve understanding of the association between NAFLD and sarcopenia. This can eventually lead to additional potential therapeutic interventions. This review attempts to give an overview of the current published literature that links sarcopenia to NAFLD, followed by a discussion of the presumably involved pathophysiological factors, and ends by discussing current unmet needs.

Relationship Between Handgrip Strength and Nonalcoholic Fatty Liver Disease: Nationwide Surveys

BACKGROUND

The association of handgrip strength with nonalcoholic fatty liver disease (NAFLD) has not been studied yet. This study investigated the relationship between handgrip strength and NAFLD in South Korean adults.

METHODS

Referring to the Korea National Health and Nutrition Examination Survey 2014 and 2015 database, South Korean adults (n = 8001, women: 55.5%) aged 19-80 years having complete data were considered for this study. Relative handgrip strength (RHGS) [average handgrip strength of both hands divided by body mass index (BMI)], hepatic steatosis index (HSI), BMI, and components of metabolic syndrome were measured. Demographics, treatment of concurrent illnesses, and health-related behaviors were assessed by using standardized questionnaires. NAFLD was defined by the HSI >36.0, alcohol consumption <20 grams/day, and negative biomarkers for chronic hepatitis B and C.

RESULTS

The prevalence of NAFLD was 30.3% ± 0.7%. Complex sample logistic regression analysis revealed that individuals with lower RHGS [per 1 standard deviation (SD) decrease] manifested higher odds of suffering from NAFLD (adjusted odds ratio: 1.47, 95% confidence interval: 1.35-1.60). Furthermore, lower RHGS was associated with higher odds for NAFLD throughout the strata of sex, age group, education, BMI category, metabolic syndrome, treatment history of illnesses, smoking status, alcohol consumption, or physical activity. The odds for NAFLD increased in the range of 1.40-1.63 with 1 SD decrease in RHGS according to the strata.

CONCLUSIONS

This study of South Korean adults suggests that lower handgrip strength is associated with NAFLD regardless of sociodemographic characteristics, weight status, metabolic syndrome, concurrent illnesses, and lifestyle.

Somatotropic Axis Dysfunction in Non-Alcoholic Fatty Liver Disease: Beneficial Hepatic and Systemic Effects of Hormone Supplementation

Background: Somatotropic axis dysfunction associated with non-alcoholic fatty liver disease (NAFLD) has potential multisystemic detrimental effects. Here, we analysed the effects of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) supplementation on liver histology, adipokine profile and muscle function in an NAFLD model. Methods: C57BL/6 mice were fed with a high fat diet (HFD) for 12 weeks and were separated into three groups treated for 4 weeks with: (1) High fat diet (HFD) (n = 10); (2) HFD + GH 9 μg/g/d (n = 10); (3) HFD + IGF-1 0.02 µg/g/d (n = 9). A control group fed a chow diet was included (n = 6). Liver histology, liver triglycerides content, serum alanine aminotransferase (ALT) activity, adiponectin and leptin serum levels, in vivo muscle strength, tetanic force and muscle fibre cross-sectional area (CSA) were measured. Results: HFD + GH and HFD + IGF-1 groups showed significantly lower ALT activity compared to HFD (p < 0.01). Liver triglyceride content in HFD + GH was decreased compared to HFD (p < 0.01). Histologic steatosis score was increased in HFD and HFD + GH group (p < 0.01), whereas HFD + IGF-1 presented no difference compared to the chow group (p = 0.3). HFD + GH group presented lower serum leptin and adiponectin levels compared to HFD. GH and IGF-1 supplementation therapy reverted HFD-induced reduction in muscle strength and CSA (sarcopenia). Conclusions: GH and IGF-1 supplementation induced significant improvement in liver steatosis, aminotransferases and sarcopenia in a diet-induced NAFLD model.

Sarcopenia and non-alcoholic fatty liver disease: Is there a relationship? A systematic review

AIM

To perform a systematic review to evaluate the incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) in adult patients with sarcopenia.

METHODS

Randomized clinical trials, cross-sectional or cohort studies including adult patients (over 18 years) with sarcopenia were selected. The primary outcomes of interest were the prevalence or incidence of NAFLD in sarcopenic patients. In the screening process, 44 full-text articles were included in the review and 41 studies were excluded.

RESULTS

Three cross-sectional studies were included. The authors attempted to perform a systematic review, but due to the differences between the studies, a qualitative synthesis was provided. The diagnosis of NAFLD was made by non-invasive methods (image methods or any surrogate markers) in all three evaluated studies. All the studies suggested that there was an independent association between sarcopenia and NAFLD.

CONCLUSION

Sarcopenia is independently associated with NAFLD and possibly to an advanced fibrosis.

Fatty Liver Index Associates with Relative Sarcopenia and GH/ IGF- 1 Status in Obese Subjects

Introduction

Recently the association between hepatic steatosis and sarcopenia has been described. GH/IGF-1 axis has been postulated to play a role in linking fatty liver and low muscle mass. The aim of our study was to explore the association between fatty liver index, sarcopenic obesity, insulin sensitivity, and GH/IGF-1 status.

Methods

427 subjects [age: 45.65±13.94 years, BMI: 36.92±6.43 kg/m²] were enrolled. Participants were divided into three groups: fatty liver index (FLI) <20, 20≥FLI<60, and FLI≥60. Body composition was assessed by DXA. The truncal fat mass (TrFM) to appendicular skeletal muscle (ASM) ratio was used as an indicator of sarcopenic obesity. ISI-Matsuda index was used.

Results

BMI, fat mass, and the TrFM/ASM ratio were higher in subjects with FLI≥60. GH, IGF-1 and ISI-Matsuda were lower in the high FLI group (all p<0.05). A significantly positive correlation between FLI and TrFM/ ASM ratio (r = 0.221, p<0.001) was found, whereas FLI levels were negatively correlated with ISI- Matsuda (r = -0.335, p<0.001), GH (r = -0.200, p = 0.006), and IGF- 1 levels (r = -0.157, p = 0.028). Stepwise linear regression analysis showed that GH levels were significantly negatively correlated with FLI, while the TrFM/ ASM ratio was positively associated with FLI, after adjustment for age, BMI, total fat mass, truncal fat mass, fat- free mass, and ISI- Matsuda.

Conclusions

Impairment of GH/IGF-1 axis seems to be associated to the risk of the development of sarcopenic obesity and ectopic fat deposition in the liver. Metabolic and hormonal derangements as determinants of ectopic fat deposition and body composition deserve to be evaluated in obese subjects.