Muscle fat content is strongly associated with NASH: A longitudinal study in patients with morbid obesity

Adverse muscle composition is a significant risk factor for all-cause mortality in NAFLD

Background & Aims

Adverse muscle composition (MC) (i.e., low muscle volume and high muscle fat) has previously been linked to poor functional performance and comorbidities in non-alcoholic fatty liver disease (NAFLD). In this study we aimed to investigate associations of all-cause mortality with liver fat, NAFLD, and MC in the UK Biobank imaging study.

Methods

Magnetic resonance images of 40,174 participants were analyzed for liver proton density fat fraction (PDFF), thigh fat-free muscle volume (FFMV) z-score, and muscle fat infiltration (MFI) using the AMRA® Researcher. Participants with NAFLD were sex-, age-, and BMI-matched to participants without NAFLD with low alcohol consumption. Adverse MC was identified using previously published cut-offs. All-cause mortality was investigated using Cox regression. Models within NAFLD were crude and subsequently adjusted for sex, age, BMI (M1), hand grip strength, physical activity, smoking, alcohol (M2), and previous cancer, coronary heart disease, type 2 diabetes (M3).

Results

A total of 5,069 participants had NAFLD. During a mean (±SD) follow-up of 3.9 (±1.4) years, 150 out of the 10,138 participants (53% men, age 64.4 [±7.6] years, BMI 29.7 [±4.4] kg/m²) died. In the matched dataset, neither NAFLD nor liver PDFF were associated with all-cause mortality, while all MC variables achieved significance. Within NAFLD, adverse MC, MFI and FFMV z-score were significantly associated with all-cause mortality and remained so in M1 and M2 (crude hazard ratios [HRs] 2.84, 95% CI 1.70-4.75, p <0.001; 1.15, 95% CI 1.07-1.24, p <0.001; 0.70, 95% CI 0.55-0.88, p <0.001). In M3, the relationship was attenuated for adverse MC and FFMV z-score (adjusted HRs 1.72, 95% CI 1.00-2.98, p = 0.051; 0.77, 95% CI 0.58-1.02, p = 0.069) but remained significant for MFI (adjusted HR 1.13, 95% CI 1.01-1.26, p = 0.026).

Conclusions

Neither NAFLD nor liver PDFF was predictive of all-cause mortality. Adverse MC was a strong predictor of all-cause mortality in individuals with NAFLD.

Impact and implications

Individuals with fatty liver disease and poor muscle health more often suffer from poor functional performance and comorbidities. This study shows that they are also at a higher risk of dying. The study results indicate that measuring muscle health (the patient's muscle volume and how much fat they have in their muscles) could help in the early detection of high-risk patients and enable targeted preventative care.

Myosteatosis, but not Sarcopenia, Predisposes NAFLD Subjects to Early Steatohepatitis and Fibrosis Progression

BACKGROUND & AIMS

Sarcopenia and myosteatosis are associated with advanced nonalcoholic fatty liver disease (NAFLD). However, muscle alterations in early stage NAFLD remain unclear.

METHODS

Patients with nonalcoholic fatty liver (NAFL) or early nonalcoholic steatohepatitis (NASH) without significant fibrosis were selected from a prospective biopsy-proven NAFLD cohort (N = 338). The skeletal muscle index and mean muscle attenuation (MA) were measured using abdominal fat computed tomography at the third lumbar vertebra level. Severe myosteatosis was defined as the lowest quartile of sex-stratified MA values.

RESULTS

Patients with early NASH (n = 87) had lower MA (45.61 ± 6.45 vs 47.48 ± 5.85 HU; P = .028) than patients with NAFL (n = 251) but a similar skeletal muscle index. Patients with more severe lobular inflammation and hepatocellular ballooning had lower MA (P = .003 and P = .041, respectively). The severe myosteatosis prevalence was higher in early NASH than in NAFL (33.3% vs 21.1%; P = .029). Patients with severe myosteatosis were more likely to have early NASH in multivariable analysis adjusted for age, sex, and metabolic factors (odds ratio, 2.45; 95% confidence interval (CI), 1.24-4.86), which was maintained after adjustment for visceral fat amount (odds ratio, 2.44; 95% CI, 1.22-4.89). During a median 29-month follow-up, 170 patients underwent repeated transient elastography. Fibrosis progression-an increase in liver stiffness measurement >2 kPa or second liver stiffness measurement ≥7 kPa-was found in 28 and 31 individuals. Severe myosteatosis was significantly associated with fibrosis progression after adjustment for various confounders (hazard ratio, 2.49; 95% CI, 1.15-5.40 and hazard ratio, 2.09; 95% CI, 1.01-4.34 for different fibrosis progression definitions).

CONCLUSIONS

Severe myosteatosis is significantly associated with early NASH and fibrosis progression in early stage NAFLD.

Interaction between sarcopenia and nonalcoholic fatty liver disease

Sarcopenia and nonalcoholic fatty liver disease (NAFLD) are common health problems related to aging. Despite the differences in their diagnostic methods, several cross-sectional and longitudinal studies have revealed the close link between sarcopenia and NAFLD. Sarcopenia and NAFLD are linked by several shared pathogenetic mechanisms, including insulin resistance, hormonal imbalance, systemic inflammation, myostatin and adiponectin dysregulation, nutritional deficiencies, and physical inactivity, thus implicating a bidirectional relationship between sarcopenia and NAFLD. However, there is not sufficient data to support a direct causal relationship between sarcopenia and NAFLD. Moreover, it is currently difficult to conclude whether sarcopenia is a risk factor for nonalcoholic steatohepatitis (NASH) or is a consequence of NASH. Therefore, this review intends to touch on the shared common mechanisms and the bidirectional relationship between sarcopenia and NAFLD.

Association between hypertension and myosteatosis evaluated by abdominal computed tomography

Few studies have examined the relationship between myosteatosis and hypertension, and no studies have enrolled an Asian population. Existing studies also found discordant results, possibly due to the use of conventional myosteatosis indices that are not sufficiently reliable and representative. Therefore, we investigated the association between myosteatosis and hypertension in Asian individuals using novel, objective computed tomography (CT) markers. The total abdominal muscle area (TAMA) was determined from abdominal CT scans taken at the L3 level. Based on the mean CT attenuation, the TAMA was divided into intramuscular adipose tissue and skeletal muscle area (SMA), which was further segmented into normal attenuation muscle area (NAMA) and low attenuation muscle area (LAMA). Among SMA/body mass index (BMI), NAMA/BMI, LAMA/BMI, and the NAMA/TAMA index, NAMA/BMI was chosen through receiver operating characteristic curves as the best predictive marker for hypertension. The hypertension risk for each quartile of NAMA/BMI was calculated by logistic regression analysis. Among the 19,766 participants, 40.3% of men and 23.8% of women had hypertension. People with hypertension showed unhealthier myosteatosis profiles than normotensive controls. Similarly, a lower NAMA/BMI was significantly associated with a greater hypertension risk. The lowest quartile group of NAMA/BMI exhibited 2.3- and 2.6-fold higher risks of hypertension than the highest quartile in men and women, respectively. In conclusion, advanced myosteatosis assessed by abdominal CT was significantly correlated with a higher risk of hypertension. Improving myosteatosis may be a new approach for preventing cardiovascular diseases, including hypertension. Advanced myosteatosis measured by abdominal CT taken at the L3 level was significantly correlated with a higher risk of hypertension even after adjusting for health behaviors, intake of lipid-lowering drugs, plasma lipid levels, and other ectopic fat distribution.

Using hyperhomocysteinemia and body composition to predict the risk of non-alcoholic fatty liver disease in healthcare workers

Purpose

This study investigated associations between serum homocysteine levels, body composition, and the probability of having nonalcoholic fatty liver disease (NAFLD) in Chinese healthcare workers.

Patients and Methods

A total of 4028 healthcare workers were enrolled in this study, and all underwent a physical examination. Body composition was measured using multifrequency bioelectrical impedance analysis.

Results

There were 1507 NAFLD patients (72.26% male, 27.74% female) and 2521 controls (39.83% male, 60.17% female). Body mass index (BMI), waistline, neck-circumference (NC), abdominal visceral fat area (AVFA), total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), glucose (Glu), homocysteinemia (hcy) were higher in the NAFLD group than controls. Additionally, the skeletal-muscle was associated with a lower risk of NAFLD, whereas BMI, waistline, NC, hyperhomocysteinemia (HHcy) were associated with a higher risk of NAFLD. The best NC cut-off point for NAFLD was 34.45 cm (sensitivity 83.3% and specificity 83.9%) in women with HHcy, and the best skeletal-muscle content cut-off point for NAFLD was 41.335% (sensitivity 74.2% and specificity 65.6%) in men with HHcy.

Conclusion

Interactions between skeletal-muscle content, NC, and HHcy may affect the incidence of NAFLD in healthcare workers. This may provide a novel approach for diagnosing NAFLD.

Muscle Fat Content Is Associated with Nonalcoholic Fatty Liver Disease and Liver Fibrosis in Chinese Adults

OBJECTIVES

Several studies have linked myosteatosis with nonalcoholic fatty liver disease (NAFLD) in individuals with obesity. The clinical significance of myosteatosis in individuals with NAFLD in the general population has not been well investigated. Here, we wanted to explore and compare the associations of NAFLD and liver fibrosis with muscle fat content and skeletal muscle mass (SMM) in a relatively large general population in China.

METHODS

We retrospectively included all participants who underwent abdominal CT scans in our health promotion center between April 2021 and October 2021. Muscle fat content was assessed by abdomen quantitative computed tomography (QCT) scans, and SMM was evaluated by bioelectrical impedance. NAFLD was assessed by ultrasonography. The NAFLD fibrosis score (NFS) and Fibrosis-4 Index (FIB-4) score were calculated to assess liver fibrosis.

RESULTS

Compared with participants without NAFLD, patients with NAFLD showed significantly increased intermuscular adipose tissue (IMAT%) (7.40±3.37% vs. 6.76±2.66%, P <0.01). According to a multiple logistic regression model, IMAT% (OR=1.091, 95% CI 1.030-1.155, P=0.003) was only independently correlated with NAFLD in obese participants. Mediation analysis showed that BMI mediated the association between IMAT% and NAFLD. In participants with NAFLD, increased IMAT% was independently associated with an increased intermediate to high risk of advanced fibrosis assessed by the NFS or FIB-4 score after adjusting for multiple potential confounders. However, SMM was only independently correlated with an intermediate to high risk for advanced fibrosis evaluated by the NFS and not by the FIB-4 score.

CONCLUSION

Increased muscle fat content is positively correlated with NAFLD and intermediate to high risk for advanced fibrosis in the general Chinese population.

Muscle fat contents rather than muscle mass determines nonalcoholic steatohepatitis and liver fibrosis in patients with severe obesity

OBJECTIVE

This study aimed to investigate the association of muscle fat contents, nonalcoholic steatohepatitis (NASH), and liver fibrosis in patients with severe obesity.

METHODS

Patients with severe obesity who underwent bariatric surgery were evaluated for NASH and liver fibrosis. Skeletal muscle was assessed by dual energy x-ray absorptiometry, and muscle fat contents (skeletal muscle fat index [SMFI]) were evaluated by computed tomography-based psoas muscle mass and density.

RESULTS

A total of 104 patients with severe obesity were enrolled (57 with nonalcoholic fatty liver disease activity score <5 and 47 with NASH with nonalcoholic fatty liver disease activity score ≥5). SMFI was higher in patients with NASH than those without NASH (mean [SD], 39.0 [14.5] vs. 46.5 [14.2] for without NASH vs. with NASH; p = 0.009). SMFI was also correlated with hepatic steatosis grade, ballooning severity, and fibrosis stage. Multiple logistic regression analysis showed that SMFI was associated with higher risk of NASH and liver fibrosis (odds ratio = 2.37, 95% CI: 1.13-4.98, p = 0.022 for NASH; odds ratio = 2.93, 95% CI: 1.32-6.48, p = 0.008 for significant liver fibrosis).

CONCLUSIONS

Muscle fat infiltration rather than muscle mass reflects the severities of hepatic steatosis and fibrosis in patients with severe obesity.

Comprehensive abdominal composition evaluation of rectal cancer patients with anastomotic leakage compared with body mass index-matched controls

BACKGROUND

Anastomotic leakage (AL) is a fatal complication in patients with rectal cancer after undergoing anterior resection. However, the role of abdominal composition in the development of AL has not been studied.

AIM

To investigate the relationship between abdominal composition and AL in rectal cancer patients after undergoing anterior resection.

METHODS

A retrospective case-matched cohort study was conducted. Complete data for 78 patients with AL were acquired and this cohort was defined as the AL group. The controls were matched for the same sex and body mass index (± 1 kg/m2). Parameters related to abdominal composition including visceral fat area (VFA), subcutaneous fat area (SFA), subcutaneous fat thickness (SFT), skeletal muscle area (SMA), skeletal muscle index (SMI), abdominal circumference (AC), anterior to posterior diameter of abdominal cavity (APD), and transverse diameter of abdominal cavity (TD) were evaluated based on computed tomography (CT) images using the following Hounsfield Unit (HU) thresholds: SFA: -190 to -30, SMA: -29 to 150, and VFA: -150 to -20. The significance of abdominal composition-related parameters was quantified using feature importance analysis; an artificial intelligence method was used to evaluate the contribution of each included variable.

RESULTS

Two thousand two hundred and thirty-eight rectal cancer patients who underwent anterior resection from 2010 to 2020 in a large academic hospital were investigated. Finally, 156 cases were enrolled in the study. Patients in the AL group showed longer operative time (225.03 ± 55.29 vs 207.17 ± 40.80, P = 0.023), lower levels of preoperative hemoglobin (123.32 ± 21.17 vs 132.60 ±1 6.31, P = 0.003) and albumin (38.34 ± 4.01 vs 40.52 ± 3.97, P = 0.001), larger tumor size (4.07 ± 1.36 vs 2.76 ± 1.28, P < 0.001), and later cancer stage (P < 0.001) compared to the controls. Patients who developed AL exhibited a larger VFA (125.68 ± 73.59 vs 97.03 ± 57.66, P = 0.008) and a smaller APD (77.30 ± 23.23 vs 92.09 ± 26.40, P < 0.001) and TD (22.90 ± 2.23 vs 24.21 ± 2.90, P = 0.002) compared to their matched controls. Feature importance analysis revealed that TD, APD, and VFA were the three most important abdominal composition-related features.

CONCLUSION

AL patients have a higher visceral fat content and a narrower abdominal structure compared to matched controls.

The link between liver fat and cardiometabolic diseases is highlighted by genome-wide association study of MRI-derived measures of body composition

Obesity and associated morbidities, metabolic associated fatty liver disease (MAFLD) included, constitute some of the largest public health threats worldwide. Body composition and related risk factors are known to be heritable and identification of their genetic determinants may aid in the development of better prevention and treatment strategies. Recently, large-scale whole-body MRI data has become available, providing more specific measures of body composition than anthropometrics such as body mass index. Here, we aimed to elucidate the genetic architecture of body composition, by conducting genome-wide association studies (GWAS) of these MRI-derived measures. We ran both univariate and multivariate GWAS on fourteen MRI-derived measurements of adipose and muscle tissue distribution, derived from scans from 33,588 White European UK Biobank participants (mean age of 64.5 years, 51.4% female). Through multivariate analysis, we discovered 100 loci with distributed effects across the body composition measures and 241 significant genes primarily involved in immune system functioning. Liver fat stood out, with a highly discoverable and oligogenic architecture and the strongest genetic associations. Comparison with 21 common cardiometabolic traits revealed both shared and specific genetic influences, with higher mean heritability for the MRI measures (h2 = .25 vs. .13, p = 1.8x10-7). We found substantial genetic correlations between the body composition measures and a range of cardiometabolic diseases, with the strongest correlation between liver fat and type 2 diabetes (rg = .49, p = 2.7x10-22). These findings show that MRI-derived body composition measures complement conventional body anthropometrics and other biomarkers of cardiometabolic health, highlighting the central role of liver fat, and improving our knowledge of the genetic architecture of body composition and related diseases.

Impact of L-ornithine L-aspartate on non-alcoholic steatohepatitis-associated hyperammonemia and muscle alterations

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common chronic liver disease in the world. Progression toward non-alcoholic steatohepatitis (NASH) is associated with alterations of skeletal muscle. One plausible mechanism for altered muscle compartment in liver disease is changes in ammonia metabolism. In the present study, we explored the hypothesis that NASH-associated hyperammonemia drives muscle changes as well as liver disease progression.

MATERIALS AND METHODS

In Alms1-mutant mice (foz/foz) fed a 60% fat diet (HFD) for 12 weeks; we investigated hepatic and muscular ammonia detoxification efficiency. We then tested the effect of an 8 week-long supplementation with L-ornithine L-aspartate (LOLA), a known ammonia-lowering treatment, given after either 4 or 12 weeks of HFD for a preventive or a curative intervention, respectively. We monitored body composition, liver and muscle state by micro computed tomography (micro-CT) as well as muscle strength by four-limb grip test.

RESULTS

According to previous studies, 12 weeks of HFD induced NASH in all foz/foz mice. Increase of hepatic ammonia production and alterations of urea cycle efficiency were observed, leading to hyperammonemia. Concomitantly mice developed marked myosteatosis. First signs of myopenia occurred after 20 weeks of diet. Early LOLA treatment given during NASH development, but not its administration in a curative regimen, efficiently prevented myosteatosis and muscle quality, but barely impacted liver disease or, surprisingly, ammonia detoxification.

CONCLUSION

Our study confirms the perturbation of hepatic ammonia detoxification pathways in NASH. Results from the interventional experiments suggest a direct beneficial impact of LOLA on skeletal muscle during NASH development, though it does not improve ammonia metabolism or liver disease.

Effects of a Family-Based Lifestyle Intervention Plus Supervised Exercise Training on Abdominal Fat Depots in Children With Overweight or Obesity: A Secondary Analysis of a Nonrandomized Clinical Trial

IMPORTANCE

Excess abdominal fat is a major determinant in the development of insulin resistance and other metabolic disorders. Increased visceral adipose tissue (VAT) seems to precede the development of insulin resistance and is therefore a prime target of childhood lifestyle interventions aimed at preventing diabetes.

OBJECTIVES

To examine the effect of added exercise to a family-based lifestyle intervention program designed to reduce VAT plus subcutaneous (ASAT), intermuscular (IMAAT), and pancreatic (PAT) adipose tissue in children with overweight or obesity and to explore the effect of changes in VAT on insulin resistance.

DESIGN, SETTING, AND PARTICIPANTS

This 2-group, parallel-design clinical trial was conducted in Vitoria-Gasteiz, Spain. A total of 116 children with overweight or obesity participated and were assigned to a 22-week family-based lifestyle program (control group [n = 57]) or the same program plus an exercise intervention (exercise group [n = 59]). Data were collected between September 1, 2014, and June 30, 2017, and imaging processing for fat depot assessments and data analysis were performed between May 1, 2019, and February 12, 2021.

INTERVENTIONS

The compared interventions consisted of a family-based lifestyle and psychoeducation program (two 90-minute sessions per month) and the same program plus supervised exercise (three 90-minute sessions per week).

MAIN OUTCOMES AND MEASURES

The primary outcome of this study was the change in VAT between baseline and 22 weeks as estimated by magnetic resonance imaging. The secondary outcomes were changes in ASAT, IMAAT, and PAT. The effect of changes in VAT area on insulin resistance was also recorded.

RESULTS

The 116 participants included in the analysis (62 girls [53.4%]) had a mean (SD) age of 10.6 (1.1) years, and 67 (57.8%) presented with obesity. Significantly greater reductions were recorded for the exercise group in terms of reduction in VAT (-18.1% vs -8.5% for the control group; P = .004), ASAT (-9.9% vs -3.0%; P = .001), and IMAAT (-6.0% vs -2.6%; P = .02) fat fractions compared with the control group. Changes in VAT explained 87.6% of the improvement seen in insulin resistance (β = -0.102 [95% CI, -0.230 to -0.002]).

CONCLUSIONS AND RELEVANCE

These findings suggest that the addition of exercise to a lifestyle intervention program substantially enhanced the positive effects on abdominal fat depots in children with overweight or obesity. In addition, the reduction in VAT seemed to largely mediate the improvement of insulin sensitivity. These results highlight the importance of including exercise as part of lifestyle therapies aimed at treating childhood obesity and preventing the development of type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02258126.

Improving the prognosis before and after liver transplantation: Is muscle a game changer?

Liver transplantation (LT) is currently the only curative treatment option for selected patients with end stage liver disease or hepatocellular carcinoma. Improving waiting list-mortality, post-transplant morbidity and mortality and refining the selection of the patients remain our current central objectives. In this field, different concepts dealing with nutrition and the muscle such as sarcopenia, malnutrition, frailty or myosteatosis have emerged as possible game changers. For more than a decade, many prospective studies have demonstrated that sarcopenia and frailty are major predictive factors of mortality in the waiting list but also after LT. Malnutrition is also a well-known risk factor for morbidity and mor-tality. Muscle composition is a newer concept giving insight on muscle quality which has also been shown to be linked to poorer outcomes. Each of these terms has a precise definition as well as pathophysiological mechanisms. The bi-directional liver-muscle axis makes sense in this situation. Defining the best, easy to use in clinical practice tools to assess muscle quality, quantity, and function in this specific population and developing quality prospective studies to identify interventional strategies that could improve these parameters as well as evaluate the effect on mortality are among the important challenges of today.

Metabolic mechanisms for and treatment of NAFLD or NASH occurring after liver transplantation

The rising tide of non-alcoholic fatty liver disease (NAFLD) associated with the obesity epidemic is a major health concern worldwide. NAFLD - specifically its more advanced form, non-alcoholic steatohepatitis (NASH)-related cirrhosis - is now the fastest growing indication for liver transplantation in the USA and Europe. Although the short-term and mid-term overall survival rates of patients who receive a liver transplant for NASH-related cirrhosis are essentially similar to those of patients who receive a transplant for other liver indications, recipients with NASH-related cirrhosis have an increased risk of waiting-list mortality and of developing recurrent liver disease and cardiometabolic complications in the longer term after liver transplantation. This Review provides a brief overview of the epidemiology of NAFLD and NASH and the occurrence of NAFLD or NASH in patients after liver transplantation for NASH and other liver indications. It also discusses the putative metabolic mechanisms underlying the emergence of NAFLD or NASH after liver transplantation as well as optimal therapeutic approaches for recipients of liver transplants, including the management of cardiometabolic comorbidities, tailored immunosuppression, lifestyle changes and pharmacotherapy for NAFLD.

Metabolic (dysfunction)-associated fatty liver disease in individuals of normal weight

Metabolic (dysfunction)-associated fatty liver disease (MAFLD) affects up to a third of the global population; its burden has grown in parallel with rising rates of type 2 diabetes mellitus and obesity. MAFLD increases the risk of end-stage liver disease, hepatocellular carcinoma, death and liver transplantation and has extrahepatic consequences, including cardiometabolic disease and cancers. Although typically associated with obesity, there is accumulating evidence that not all people with overweight or obesity develop fatty liver disease. On the other hand, a considerable proportion of patients with MAFLD are of normal weight, indicating the importance of metabolic health in the pathogenesis of the disease regardless of body mass index. The clinical profile, natural history and pathophysiology of patients with so-called lean MAFLD are not well characterized. In this Review, we provide epidemiological data on this group of patients and consider overall metabolic health and metabolic adaptation as a framework to best explain the pathogenesis of MAFLD and its heterogeneity in individuals of normal weight and in those who are above normal weight. This framework provides a conceptual schema for interrogating the MAFLD phenotype in individuals of normal weight that can translate to novel approaches for diagnosis and patient care.

Immune mechanisms linking metabolic injury to inflammation and fibrosis in fatty liver disease - novel insights into cellular communication circuits

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease and is emerging as the leading cause of cirrhosis, liver transplantation and hepatocellular carcinoma (HCC). NAFLD is a metabolic disease that is considered the hepatic manifestation of the metabolic syndrome; however, during the evolution of NAFLD from steatosis to non-alcoholic steatohepatitis (NASH), to more advanced stages of NASH with liver fibrosis, the immune system plays an integral role. Triggers for inflammation are rooted in hepatic (lipid overload, lipotoxicity, oxidative stress) and extrahepatic (gut-liver axis, adipose tissue, skeletal muscle) systems, resulting in unique immune-mediated pathomechanisms in NAFLD. In recent years, the implementation of single-cell RNA-sequencing and high dimensional multi-omics (proteogenomics, lipidomics) and spatial transcriptomics have tremendously advanced our understanding of the complex heterogeneity of various liver immune cell subsets in health and disease. In NAFLD, several emerging inflammatory mechanisms have been uncovered, including profound macrophage heterogeneity, auto-aggressive T cells, the role of unconventional T cells and platelet-immune cell interactions, potentially yielding novel therapeutics. In this review, we will highlight the recent discoveries related to inflammation in NAFLD, discuss the role of immune cell subsets during the different stages of the disease (including disease regression) and integrate the multiple systems driving inflammation. We propose a refined concept by which the immune system contributes to all stages of NAFLD and discuss open scientific questions arising from this paradigm shift that need to be unravelled in the coming years. Finally, we discuss novel therapeutic approaches to target the multiple triggers of inflammation, including combination therapy via nuclear receptors (FXR agonists, PPAR agonists).

Effect of a Multicomponent Intervention on Hepatic Steatosis Is Partially Mediated by the Reduction of Intermuscular Abdominal Adipose Tissue in Children With Overweight or Obesity: The EFIGRO Project

OBJECTIVE

In adults, there is evidence that improvement of metabolic-associated fatty liver disease (MAFLD) depends on the reduction of myosteatosis. In children, in whom the prevalence of MAFLD is alarming, this muscle-liver crosstalk has not been tested. Therefore, we aimed to explore whether the effects of a multicomponent intervention on hepatic fat is mediated by changes in intermuscular abdominal adipose tissue (IMAAT) in children with overweight/obesity.

RESEARCH DESIGN AND METHODS

A total of 116 children with overweight/obesity were allocated to a 22-week family-based lifestyle and psychoeducational intervention (control group, n = 57) or the same intervention plus supervised exercise (exercise group, n = 59). Hepatic fat percentage and IMAAT were acquired by MRI at baseline and at the end of the intervention.

RESULTS

Changes in IMAAT explained 20.7% of the improvements in hepatic steatosis (P < 0.05). Only children who meaningfully reduced their IMAAT (i.e., responders) had improved hepatic steatosis at the end of the intervention (within-group analysis: responders -20% [P = 0.005] vs. nonresponders -1.5% [P = 0.803]). Between-group analysis showed greater reductions in favor of IMAAT responders compared with nonresponders (18.3% vs. 0.6%, P = 0.018), regardless of overall abdominal fat loss.

CONCLUSIONS

The reduction of IMAAT plays a relevant role in the improvement of hepatic steatosis after a multicomponent intervention in children with overweight/obesity. Indeed, only children who achieved a meaningful reduction in IMAAT at the end of the intervention had a reduced percentage of hepatic fat independent of abdominal fat loss. Our findings suggest that abdominal muscle fat infiltration could be a therapeutic target for the treatment of MAFLD in childhood.

Body composition and the skeletal muscle compartment in liver transplantation: Turning challenges into opportunities

Frailty, nutritional status, and body composition are increasingly under the spotlight of interest in various clinical scenarios including liver transplantation. To address the rapidly accumulating evidence in this field, recent European and North American practice guidelines have clearly underlined the clinical importance of nutritional status and body composition with adopting their assessment in patients with liver disease and in transplant candidates into their recommendations. While earlier reports, and therefore present guidelines, were focusing predominantly on quantitative alterations of the skeletal muscle mass (sarcopenia), recent studies have identified qualitative alterations such as intramuscular fat accumulation (myosteatosis) and sarcopenic obesity as emerging risk factors for poor clinical outcomes. In this review, the role of body composition in the context of liver transplantation will be discussed with a focus on the skeletal muscle compartment. A brief overview of current assessment modalities including their limitations, diagnostic challenges, prognostic significance, and pathophysiology are included. Possibilities to incorporate body composition parameters into clinical decision making are discussed. In addition, novel trends and remaining challenges in the therapeutic targeting of body composition and the skeletal muscle compartment are highlighted.

Elevated alpha-fetoprotein in asymptomatic adults: Clinical features, outcome, and association with body composition

Background and aim

Apparently healthy individuals with elevated serum alpha-fetoprotein (AFP) levels (>7 ng/mL) for unknown causes visit clinics. We investigated their clinical characteristics, outcomes, and relationship with body fat deposition and muscle mass.

Methods

The case group included asymptomatic 137 individuals with “elevated AFP level” (R772) diagnostic code from 2009 to 2018 in a tertiary hospital. The control group enrolled 274 age- and sex-matched patients with <5 cm hepatic hemangiomas. Hepatic, visceral, and psoas muscle adiposity and psoas muscle index (PMI) were measured in the subgroups of 45 cases and 90 controls with pre-contrast computed tomography (CT) images.

Results

The case group (mean age 47.5 years, male 35.8%) showed higher AFP levels (10.3 vs 2.5 ng/mL, p<0.001) and total bilirubin (0.8 vs 0.7 mg/dL, p<0.001), but a lower body mass index (22.2 vs 23.3 kg/m², p = 0.011) and alanine aminotransferase levels (17.0 vs 19.0 IU/L, p = 0.047) than the controls. During 13 months of median follow-up, there was no cancer or liver disease development. The AFP levels were stable. In the subgroups with CT images, cases showed a lower proportion of hepatic steatosis (4.4% vs 18.9%, p = 0.023), higher psoas muscle attenuation (48.2 vs 43.8 Hounsfield units, p<0.001) and higher PMI (5.7 vs 4.2 cm²/m², p<0.001) than the controls.

Conclusion

Elevated AFP levels in asymptomatic individuals may play a role in expressing a protective phenotype against hepatic steatosis, myosteatosis, and sarcopenia. AFP levels in patients with elevated AFP were stable during follow-up without liver injury or cancer development. Interaction between AFP expression and steatosis warrants further study.

Contribution of organokines in the development of NAFLD/NASH associated hepatocellular carcinoma

Globally the incidence of hepatocellular carcinoma (HCC) is on an upsurge. Evidence is accumulating that liver disorders like nonalcoholic fatty liver disease (NAFLD) and its more progressive form nonalcoholic steatohepatitis (NASH) are associated with increased risk of developing HCC. NAFLD has a prevalence of about 25% and 50%-90% in obese population. With the growing burden of obesity epidemic worldwide, HCC presents a major healthcare burden. While cirrhosis is one of the major risk factors of HCC, available literature suggests that NAFLD/NASH associated HCC also develops in minimum or noncirrhotic livers. Therefore, there is an urgent need to understand the pathogenesis and risk factors associated with NAFLD and NASH related HCC that would help in early diagnosis and favorable prognosis of HCC secondary to NAFLD. Adipokines, hepatokines and myokines are factors secreted by adipocytes, hepatocytes and myocytes, respectively, playing essential roles in cellular homeostasis, energy balance and metabolism with autocrine, paracrine and endocrine effects. In this review, we endeavor to focus on the role of these organokines in the pathogenesis of NAFLD/NASH and its progression to HCC to augment the understanding of the factors stimulating hepatocytes to acquire a malignant phenotype. This shall aid in the development of novel therapeutic strategies and tools for early diagnosis of NAFLD/NASH and HCC.

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.

Impact of Sarcopenia and Myosteatosis in Non-Cirrhotic Stages of Liver Diseases: Similarities and Differences across Aetiologies and Possible Therapeutic Strategies

Sarcopenia is defined as a loss of muscle strength, mass and function and it is a predictor of mortality. Sarcopenia is not only a geriatric disease, but it is related to several chronic conditions, including liver diseases in both its early and advanced stages. Despite the increasing number of studies exploring the role of sarcopenia in the early stages of chronic liver disease (CLD), its prevalence and the relationship between these two clinical entities are still controversial. Myosteatosis is characterized by fat accumulation in the muscles and it is related to advanced liver disease, although its role in the early stages is still under researched. Therefore, in this narrative review, we firstly aimed to evaluate the prevalence and the pathogenetic mechanisms underlying sarcopenia and myosteatosis in the early stage of CLD across different aetiologies (mainly non-alcoholic fatty liver disease, alcohol-related liver disease and viral hepatitis). Secondly, due to the increasing prevalence of sarcopenia worldwide, we aimed to revise the current and the future therapeutic approaches for the management of sarcopenia in CLD.

Muscle Fat Content Is Strongly Associated With Hyperuricemia: A Cross-Sectional Study in Chinese Adults

Studies have indicated that the skeletal muscle mass and strength was related to serum uric acid (UA), but there is a lack of research on the association of skeletal muscle fat content with UA. The purpose of this cross-sectional study is to investigate the correlation of skeletal muscle fat index (SMFI) and hyperuricemia (HUA) in Chinese adults. 500 subjects (306 men and 194 women) were included in the study. The participants were divided into four groups according to SMFI quartiles. Pearson's correlations between SMFI and metabolic variables were calculated. Logistic regression analysis was used to estimate the association between the quartiles of SMFI and risk of hyperuricemia. UA showed a positive association with SMFI after adjusted for BMI, age and gender. A significant association between the SMFI and risk of HUA was found, the OR for HUA was 2.79 (95% CI 1.18-6.59, p<0.05) in Q2, 2.41(95% CI 1.00-5.81, p<0.05) in Q3, and 2.63 (95% CI 1.03-6.72, p<0.05) in Q4, after adjusted for BMI. In conclusion, the SMFI was significantly associated with the level of serum UA, and the higher SMFI may indicate a higher risk of HUA, independent of BMI.

FAT AND MUSCLE COMPONENTS OF BODY WEIGHT AND THEIR RELATIONSHIP WITH THE CONCENTRATION OF SERUM ADIPOKINES IN PATIENTS WITH NONALCOHOLIC FATTY LIVER DISEASE

OBJECTIVE

The aim: Identify differences in indexes of body fat and muscle masses, as well as blood adipokines in patients with nonalcoholic fatty liver disease, from gender-appropriate healthy men and women.

PATIENTS AND METHODS

Materials and methods: 135 patients with non-alcoholic fatty liver disease with normal, overweight and obesity and 20 almost healthy individuals for the control group were examined. Verification of the diagnosis was performed in accordance with the recommendations of the unified clinical protocol. An anthropometric examination of patients was performed according to the method, which included the determination of 48 anthropometric parameters. The formulas determined the absolute amount of adipose and muscle tissue. Levels of adipokines (leptin and adiponectin) were determined by enzyme-linked immunosorbent assay.

RESULTS

Results: According to Matiegka, body fat was 30.2-35.2% higher, and muscle body weight was 17.4-29.1% lower in patients with non-alcoholic fatty liver disease compared to healthy people. The concentration of leptin in the serum of patients with nonalcoholic fatty liver disease was statistically significantly higher (2.05-3.78 times) compared with almost healthy individuals. At the same time, the indicators of adiponectin concentration (1.54-1.92 times) and log A / L index (1.16-1.32 times) were lower. Correlations between changes in muscle mass and adipokines concentration have been established.

CONCLUSION

Conclusions: In addition to the known increase in body fat in non-alcoholic fatty liver disease, there has been established a significant decrease in muscle mass. A direct correlation between adiponectin concentration and an inverse correlation between leptin levels and muscle mass in patients with nonalcoholic fatty liver disease was found.

Quality Matters as Much as Quantity of Skeletal Muscle: Clinical Implications of Myosteatosis in Cardiometabolic Health

Although age-related changes in skeletal muscles are closely associated with decreases in muscle strength and functional decline, their associations with cardiometabolic diseases in the literature are inconsistent. Such inconsistency could be explained by the fact that muscle quality-which is closely associated with fatty infiltration of the muscle (i.e., myosteatosis)-is as important as muscle quantity in cardiometabolic health. However, muscle quality has been less explored compared with muscle mass. Moreover, the standard definition of myosteatosis and its assessment methods have not been established yet. Recently, some techniques using single axial computed tomography (CT) images have been introduced and utilized in many studies, as the mass and quality of abdominal muscles could be measured opportunistically on abdominal CT scans obtained during routine clinical care. Yet, the mechanisms by which myosteatosis affect metabolic and cardiovascular health remain largely unknown. In this review, we explore the recent advances in the assessment of myosteatosis and its changes associated with aging. We also review the recent literature on the clinical implication of myosteatosis by focusing on metabolic and cardiovascular diseases. Finally, we discuss the challenges and unanswered questions that need addressing to set myosteatosis as a therapeutic target for the prevention or treatment of cardiometabolic diseases.

Intestine-liver crosstalk in Type 2 Diabetes and non-alcoholic fatty liver disease

Type 2 diabetes (T2D) and Non-Alcoholic Fatty Liver Disease (NAFLD) are pathologies whose prevalence continues to increase worldwide. Both diseases are precipitated by an excessive caloric intake, which promotes insulin resistance and fatty liver. The role of the intestine and its crosstalk with the liver in the development of these metabolic diseases is receiving increasing attention. Alterations in diet-intestinal microbiota interactions lead to the dysregulation of intestinal functions, resulting in altered metabolite and energy substrate production and increased intestinal permeability. Connected through the portal circulation, these changes in intestinal functions impact the liver and other metabolic organs, such as visceral adipose tissue, hence participating in the development of insulin resistance, and worsening T2D and NAFLD. Thus, targeting the intestine may be an efficient therapeutic approach to cure T2D and NAFLD. In this review, we will first introduce the signaling pathways linking T2D and NAFLD. Next, we will address the role of the gut-liver crosstalk in the development of T2D and NAFLD, with a particular focus on the gut microbiota and the molecular pathways behind the increased intestinal permeability and inflammation. Finally, we will summarize the therapeutic strategies which target the gut and its functions and are currently used or under development to treat T2D and NAFLD.

The Association between Low Muscle Mass and Hepatic Steatosis in Asymptomatic Population in Korea

Background: An association between low muscle mass and nonalcoholic fatty liver disease (NAFLD) has been suggested. We investigated this relationship using controlled attenuation parameter (CAP). Methods: A retrospective cohort of subjects had liver FibroScan^® (Echosens, Paris, France) and bioelectrical impedance analyses during health screening exams. Low muscle mass was defined based on appendicular skeletal muscle mass/body weight ratios of one (class I) or two (class II) standard deviations below the sex-specific mean for healthy young adults. Results: Among 960 subjects (58.1 years; 67.4% male), 344 (45.8%, class I) and 110 (11.5%, class II) had low muscle mass. After adjusting for traditional metabolic risk factors, hepatic steatosis, defined as a CAP ≥ 248 dB/m, was associated with low muscle mass (class I, odds ratio (OR): 1.96, 95% confidence interval (CI): 1.38–2.78; class II, OR: 3.33, 95% CI: 1.77–6.26). A dose-dependent association between the grade of steatosis and low muscle mass was also found (class I, OR: 1.88, for CAP ≥ 248, <302; OR: 2.19, in CAP ≥ 302; class II, OR: 2.33, for CAP ≥ 248, <302; OR: 6.17, in CAP ≥ 302). High liver stiffness was also significantly associated with an increased risk of low muscle mass (class I, OR: 1.97, 95% CI: 1.31–2.95; class II, OR: 2.96, 95% CI: 1.51–5.78). Conclusion: Hepatic steatosis is independently associated with low muscle mass in a dose-dependent manner. The association between hepatic steatosis and low muscle mass suggests that particular attention should be given to subjects with NAFLD for an adequate assessment of muscle mass.

Muscle mass depletion in chronic liver diseases: An accelerated model of aging or a distinct entity?

Sarcopenia was initially defined as loss of muscle mass, strength and function related to aging. This phenomenon is a multifactorial process. The evaluation of the geriatric population in which sarcopenia has extensively been studied opens the field for other chronic diseases. Cirrhosis is one of them and the term "sarcopenia" is now also used in this pathological situation. It must be emphasized that the pathophysiology of sarcopenia in cirrhosis is likely different from the pathogenesis in geriatric patients. Furthermore, cirrhosis has heterogeneous causes. Therefore, we need a better understanding of the changes in muscle physiology specifically in chronic liver diseases as well as easy, accurate, reproducible and validated tools, taking into consideration etiology specific aspects to identify sarcopenia in every cirrhotic patient.

A dynamic association between myosteatosis and liver stiffness: Results from a prospective interventional study in obese patients

Background & Aims

Retrospective cross-sectional studies linked sarcopenia and myosteatosis with metabolic dysfunction-associated fatty liver disease (MAFLD). Here, we wanted to clarify the dynamic relationship between sarcopenia, myosteatosis, and MAFLD.

Methods

A cohort of 48 obese patients was randomised for a dietary intervention consisting of 16 g/day of inulin (prebiotic) or maltodextrin (placebo) supplementation. Before and after the intervention, we evaluated liver steatosis and stiffness with transient elastography (TE); we assessed skeletal muscle index (SMI) and skeletal muscle fat index (SMFI) (a surrogate for absolute fat content in muscle) using computed tomography (CT) and bioelectrical impedance analysis (BIA).

Results

At baseline, sarcopenia was uncommon in patients with MAFLD (4/48, 8.3%). SMFI was higher in patients with high liver stiffness than in those with low liver stiffness (640.6 ± 114.3 cm²/ Hounsfield unit [HU] vs. 507.9 ± 103.0 cm²/HU, p = 0.001). In multivariate analysis, SMFI was robustly associated with liver stiffness even when adjusted for multiple confounders (binary logistic regression, p <0.05). After intervention, patients with inulin supplementation lost weight, but this was not associated with a decrease in liver stiffness. Remarkably, upon intervention (being inulin or maltodextrin), patients who lowered their SMFI, but not those who increased SMI, had a 12.7% decrease in liver stiffness (before = 6.36 ± 2.15 vs. after = 5.55 ± 1.97 kPa, p = 0.04).

Conclusions

Myosteatosis, but not sarcopenia, is strongly and independently associated with liver stiffness in obese patients with MAFLD. After intervention, patients in which the degree of myosteatosis decreased reduced their liver stiffness, irrespective of body weight loss or prebiotic treatment. The potential contribution of myosteatosis to liver disease progression should be investigated.

Clinical Trials registration number

NCT03852069.

Lay summary

The fat content in skeletal muscles (or myosteatosis) is strongly associated with liver stiffness in obese patients with MAFLD. After a dietary intervention, patients in which the degree of myosteatosis decreased also reduced their liver stiffness. The potential contribution of myosteatosis to liver disease progression should be investigated.

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Low-radiation CT scan enables muscle evaluation (quantity and composition).

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Muscle mass is not low in patients with MAFLD and high liver stiffness.

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In contrast, myosteatosis is strongly associated with liver stiffness.

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Lower myosteatosis after dietary intervention is associated with improved MAFLD.