Visceral abdominal and subfascial femoral adipose tissue have opposite associations with liver fat in overweight and obese premenopausal caucasian women

Recent Epidemiology and Risk Factors of Nonalcoholic Fatty Liver Disease

Because of the global obesity epidemic, the incidence and prevalence of nonalcoholic fatty liver disease (NAFLD) have increased worldwide, including among Koreans. Recently, the incidence rate of NAFLD in Korea was reported to be 45.1 per 1,000 person-years, and the prevalence as approximately 30% depending on the diagnostic methods used. The incidence of advanced fibrosis and hepatocellular carcinoma, as well as all-cause and liver-related mortality in NAFLD patients has increased substantially, imposing considerable public health costs in Korea. Genetic, demographic, environmental, and clinical factors are involved in the pathogenesis of NAFLD. Some genetic variants, such as patatin-like phospholipase domain-containing 3 (PNPLA-3) and sorting and assembly machinery component 50 (SAMM-50), play a major role in the occurrence of NAFLD. The risk of NAFLD and fibrosis increases with advancing age and in men. Nutritional factors, inadequate exercise, and sleep duration are also associated with increased risk of NAFLD. Obesity is a major risk factor for NAFLD; however, NAFLD in lean individuals has been noted in recent studies. Insulin resistance, type 2 diabetes, and metabolic syndrome and its components are closely associated with NAFLD development and liver fibrosis with various underlying mechanisms. Sarcopenia likely shares a common pathophysiology with NAFLD. The rapidly increasing incidence and prevalence of NAFLD and its complications, as well as the associated healthcare burden, warrant early assessment of NAFLD and its risk factors to prevent NAFLD-related complications in high risk groups.

A. A, Elsayed SH. Effect of focused ultrasound cavitation augmented with aerobic exercise on abdominal and intrahepatic fat in patients with non-alcoholic fatty liver disease: A randomized controlled trial

OBJECTIVES

The study aimed to examine the effect of focused ultrasound cavitation augmented with aerobic exercise on localized abdominal and intrahepatic fat in fatty liver patients.

METHODS

34 fatty liver patients aged 30-45 with a body mass index (BMI) of 30-40 kg/m2 were randomly assigned into two equally numbered groups. Group A received focused ultrasound cavitation and moderate aerobic exercise for three months, while Group B (control group) received moderate aerobic exercise only. Abdominal subcutaneous fat volume, visceral fat volume, liver-to-spleen ratio (L/S ratio), body weight, BMI, and waist circumference were measured both before and after the study period.

RESULTS

Both groups showed significant improvements in subcutaneous fat volume, visceral fat volume, body weight, BMI, and waist circumference relative to baseline where (P < 0.001), with a higher percentage in group A. L/S ratio only showed a significant improvement in group A. Between-group differences were noteworthy regarding L/S ratio and waist circumference where (P < 0.0001).

CONCLUSION

While substantial risky measures in non-alcoholic fatty liver disease have been modified by aerobic exercise, its combination with focused ultrasound cavitation causes more notable effects on the reduction of abdominal and intrahepatic fat, making it a superior option.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04161703.

Impact of Gut and Metabolic Hormones on Feeding Reward

Ingestion of food activates a cascade of endocrine responses (thereby reflecting a contemporaneous feeding status) that include the release of hormones from the gastrointestinal (GI) tract, such as cholecystokinin (CCK), glucagonlike peptide YY (PYY), peptide PP, and oleoylethanolamide, as well as suppression of ghrelin secretion. The pancreas and adipose tissue, on the other hand, release hormones that serve as a measure of the current metabolic state or the long-term energy stores, that is, insulin, leptin, and adiponectin. It is well known and intuitively understandable that these hormones target either directly (by crossing the blood-brain barrier) or indirectly (e.g., via vagal input) the "homeostatic" brainstem-hypothalamic pathways involved in the regulation of appetite. The current article focuses on yet another target of the metabolic and GI hormones that is critical in inducing changes in food intake, namely, the reward system. We discuss the physiological basis of this functional interaction, its importance in the control of appetite, and the impact that disruption of this crosstalk has on energy intake in select physiological and pathophysiological states. We conclude that metabolic and GI hormones have a capacity to strengthen or weaken a response of the reward system to a given food, and thus, they are fundamental in ensuring that feeding reward is plastic and dependent on the energy status of the organism. © 2021 American Physiological Society. Compr Physiol 11:1425-1447, 2021.

The ZJU index is a powerful surrogate marker for NAFLD in severely obese North American women

Introduction

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the western world and is highly associated with multiple cardiometabolic complications. The Zhejiang University (ZJU) index was first developed to predict NAFLD in Chinese populations, where it was shown to have better predictive value than other currently used indices. The aims of the present study were to 1) determine the diagnostic accuracy of ZJU index in identifying NAFLD in a well-phenotyped cohort of obese middle-aged American women and 2) compare its performance with other non-invasive indices for NAFLD identification.

Methods

To achieve this goal, we performed a retrospective analysis of a prospectively-collected cohort of participants enrolled in a weight loss trial for severe obesity (RENEW, clinicaltrials.gov identifier: NCT00712127). One hundred and seven women between the age of 30 and 55 with obesity class II (BMI 35–39.9 kg/m²) or class III (BMI ≥ 40 kg/m²) were recruited for analyses. Hepatic steatosis was measured using liver/spleen attenuation ratio (L/S ratio) from unenhanced abdominal computed tomography. Beside ZJU index, hepatic steatosis index (HSI), lipid accumulation production index (LAPI), and visceral adiposity index (VAI) were also determined and to compare their performance in predicting NAFLD.

Results

Of 107 obese women in the study, 40 (37.4%) met imaging criteria for NAFLD using cut-off value of L/S ratio < 1.1. The ZJU index was positively correlated with HIS, LAPI, but not VAI. The area under the curve was highest for the ZJU index (AUC = 0.742, 95% CI:0.647–0.837), followed by HSI (AUC = 0.728, 95% CI:0.631–0.825), LAPI (AUC = 0.682, CI:0.583–0.781), and VAI (AUC = 0.621, 95% CI:0.518–0.725), respectively, using the Youden method.

Conclusion

The ZJU index is a powerful surrogate marker for NAFLD in severely obese western females and its predictive value was better than that of other commonly used indices for predicting NAFLD. Our study is the first to suggest that the ZJU index could be a promising model for use in western as well as Chinese populations.

The Epidemiology, Risk Profiling and Diagnostic Challenges of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) encompasses a wide spectrum of liver damage from the more prevalent (75%⁻80%) and nonprogressive nonalcoholic fatty liver (NAFL) category to its less common and more ominous subset, nonalcoholic steatohepatitis (NASH). NAFLD is now the most common cause of chronic liver disease in the developed world and is a leading indication for liver transplantation in United States (US). The global prevalence of NAFLD is estimated to be 25%, with the lowest prevalence in Africa (13.5%) and highest in the Middle East (31.8%) and South America (30.4%). The increasing incidence of NAFLD has been associated with the global obesity epidemic and manifestation of metabolic complications, including hypertension, diabetes, and dyslipidemia. The rapidly rising healthcare and economic burdens of NAFLD warrant institution of preventative and treatment measures in the high-risk sub-populations in an effort to reduce the morbidity and mortality associated with NAFLD. Genetic, demographic, clinical, and environmental factors may play a role in the pathogenesis of NAFLD. While NAFLD has been linked with various genetic variants, including PNPLA-3, TM6SF2, and FDFT1, environmental factors may predispose individuals to NAFLD as well. NAFLD is more common in older age groups and in men. With regards to ethnicity, in the US, Hispanics have the highest prevalence of NAFLD, followed by Caucasians and then African-Americans. NAFLD is frequently associated with the components of metabolic syndrome, such as type 2 diabetes mellitus (T2DM), obesity, hypertension, and dyslipidemia. Several studies have shown that the adoption of a healthy lifestyle, weight loss, and pro-active management of individual components of metabolic syndrome can help to prevent, retard or reverse NAFLD-related liver damage. Independently, NAFLD increases the risk of premature cardiovascular disease and associated mortality. For this reason, a case can be made for screening of NAFLD to facilitate early diagnosis and to prevent the hepatic and extra-hepatic complications in high risk sub-populations with morbid obesity, diabetes, and other metabolic risk factors.

Hypothalamic Integration of the Endocrine Signaling Related to Food Intake

Hypothalamic integration of gastrointestinal and adipose tissue-derived hormones serves as a key element of neuroendocrine control of food intake. Leptin, adiponectin, oleoylethanolamide, cholecystokinin, and ghrelin, to name a few, are in a constant "cross talk" with the feeding-related brain circuits that encompass hypothalamic populations synthesizing anorexigens (melanocortins, CART, oxytocin) and orexigens (Agouti-related protein, neuropeptide Y, orexins). While this integrated neuroendocrine circuit successfully ensures that enough energy is acquired, it does not seem to be equally efficient in preventing excessive energy intake, especially in the obesogenic environment in which highly caloric and palatable food is constantly available. The current review presents an overview of intricate mechanisms underlying hypothalamic integration of energy balance-related peripheral endocrine input. We discuss vulnerabilities and maladaptive neuroregulatory processes, including changes in hypothalamic neuronal plasticity that propel overeating despite negative consequences.

Automated analysis of liver fat, muscle and adipose tissue distribution from CT suitable for large-scale studies

Computed Tomography (CT) allows detailed studies of body composition and its association with metabolic and cardiovascular disease. The purpose of this work was to develop and validate automated and manual image processing techniques for detailed and efficient analysis of body composition from CT data. The study comprised 107 subjects examined in the Swedish CArdioPulmonary BioImage Study (SCAPIS) using a 3-slice CT protocol covering liver, abdomen, and thighs. Algorithms were developed for automated assessment of liver attenuation, visceral (VAT) and subcutaneous (SAT) abdominal adipose tissue, thigh muscles, subcutaneous, subfascial (SFAT) and intermuscular adipose tissue. These were validated using manual reference measurements. SFAT was studied in selected subjects were the fascia lata could be visually identified (approx. 5%). In addition, precision of manual measurements of intra- (IPAT) and retroperitoneal adipose tissue (RPAT) and deep- and superficial SAT was evaluated using repeated measurements. Automated measurements correlated strongly to manual reference measurements. The SFAT depot showed the weakest correlation (r = 0.744). Automated VAT and SAT measurements were slightly, but significantly overestimated (≤4.6%, p ≤ 0.001). Manual segmentation of abdominal sub-depots showed high repeatability (CV ≤ 8.1%, r ≥ 0.930). We conclude that the low dose CT-scanning and automated analysis makes the setup suitable for large-scale studies.

Epidemiological modifiers of non-alcoholic fatty liver disease: Focus on high-risk groups

An improved understanding of non-alcoholic fatty liver disease epidemiology would lead to identification of individuals at high risk of developing chronic liver disease and extra-hepatic complications, thus contributing to more effective case finding of non-alcoholic fatty liver disease among selected groups. We aimed to illustrate the epidemiology of non-alcoholic fatty liver disease in high-risk groups, which were identified based on existing literature. To this end, PubMed was searched to retrieve original articles published until May 2015 using relevant and pertinent keywords "nonalcoholic fatty liver disease" and "diabetes", "obesity", "hyperlipidaemia", "familial heterozygous hypobetalipoproteinaemia", "hypertension", "metabolic syndrome", "ethnicity", "family history" or "genetic polymorphisms". We found that age, sex and ethnicity are major physiological modifiers of the risk of non-alcoholic fatty liver disease, along with belonging to "non-alcoholic fatty liver disease families" and carrying risk alleles for selected genetic polymorphisms. Metabolic syndrome, diabetes, obesity, mixed hyperlipidaemia and hypocholesterolaemia due to familial hypobetalipoproteinaemia are the major metabolic modifiers of non-alcoholic fatty liver disease risk. Compared with these metabolic conditions, however, arterial hypertension appears to carry a relatively more modest risk of non-alcoholic fatty liver disease. A better understanding of the epidemiology of non-alcoholic fatty liver disease may result in a more liberal policy of case finding among high-risk groups.

Ultrasound, anthropometry and bioimpedance: a comparison in predicting fat deposition in non-alcoholic fatty liver disease

PURPOSE

The aim of our study was the evaluation of anthropometric measurements [waist circumference and sagittal abdominal diameter (SAD)] and abdominal bioelectrical impedance analysis (BIA) (ViScan, TANITA) in comparison to several abdominal ultrasonographic (US) measurements to estimate visceral fat deposition and liver steatosis in a population of 105 subjects.

METHODS

All 105 patients underwent a complete anthropometric evaluation, blood sample for the determination of total cholesterol, HDL cholesterol, triglycerides, glucose, insulin, high-sensitivity C-reactive protein, BIA and US measurements (peritoneal, pre-peritoneal, peri-renal, para-renal and peri-hepatic fat thickness).

RESULTS

All the ultrasonographic markers considered in our study are related to the presence of non-alcoholic fatty liver disease (NAFLD), and so is true for SAD. Comparing ROC curves, peritoneal fat tissue thickness, SAD and ViScan visceral index are significantly better than waist circumference in predicting the presence of NAFLD (AUC 0.79 ± 0.04; 0.81 ± 0.05; 0.82 ± 0.04 vs 0.76 ± 0.05, respectively).

CONCLUSIONS

According to our data, various methods may be useful in evaluating NAFLD, but only ViScan visceral index, US peritoneal fat thickness and SAD are better than waist circumference. Among them, SAD is the most promising, due to its small cost and time consumption.

What is the role of adiponectin in obesity related non-alcoholic fatty liver disease?

Non-alcoholic fatty liver disease (NAFLD) is recognized as the most common type of chronic liver disease in Western countries. Insulin resistance is a key factor in the pathogenesis of NAFLD, the latter being considered as the hepatic component of insulin resistance or obesity. Adiponectin is the most abundant adipose-specific adipokine. There is evidence that adiponectin decreases hepatic and systematic insulin resistance, and attenuates liver inflammation and fibrosis. Adiponectin generally predicts steatosis grade and the severity of NAFLD; however, to what extent this is a direct effect or related to the presence of more severe insulin resistance or obesity remains to be addressed. Although there is no proven pharmacotherapy for the treatment of NAFLD, recent therapeutic strategies have focused on the indirect upregulation of adiponectin through the administration of various therapeutic agents and/or lifestyle modifications. In this adiponectin-focused review, the pathogenetic role and the potential therapeutic benefits of adiponectin in NAFLD are analyzed systematically.

Non-alcoholic fatty liver disease and obesity: not all about body mass index

Patients with nonalcoholic fatty liver (NAFLD) are typically obese and confounded by the metabolic syndrome. The body mass index (BMI) is often used as a surrogate marker of obesity defined as a BMI >30 λkg/m(2). However, it is now apparent that it is the distribution of body fat (not total fat) that is associated with NAFLD. Many patients (as many as 25%) with NAFLD are nonobese. This is particularly true in Asians who have a significantly increased risk of cardiovascular disease and diabetes even among those with a normal BMI. It is important for clinicians to be aware that these "metabolically obese" NAFLD patients should be monitored for the metabolic syndrome and its associated adverse outcomes irrespective of their BMI.

Appetite regulation and weight control: the role of gut hormones

The overwhelming increase in the prevalence of overweight and obesity in recent years represents one of the greatest threats to the health of the developed world. Among current treatments, however, gastrointestinal (GI) surgery remains the only approach capable of achieving significant weight loss results with long-term sustainability. As the obesity prevalence approaches epidemic proportions, the necessity to unravel the mechanisms regulating appetite control has garnered significant attention. It is well known that physical activity and food intake regulation are the two most important factors involved in body weight control. To regulate food intake, the brain must alter appetite. With this realization has come increased efforts to understand the intricate interplay between gut hormones and the central nervous system, and the role of these peptides in food intake regulation through appetite modulation. This review discusses the central mechanisms involved in body weight regulation and explores a suite of well characterized and intensely investigated anorexigenic and orexigenic gut hormones. Their appetite-regulating capabilities, post-GI surgery physiology and emerging potential as anti-obesity therapeutics are then reviewed.