Quantitation and localization of regional body fat distribution--a comparison between magnetic resonance imaging and somatometry

Whole-Mount Imaging of Adipose Tissue Macrophages

The adipose tissue comprises highly heterogeneous macrophage populations, which play critical roles in the regulation of adipose tissue function and dysfunction during health and disease. Whole-amount staining is a powerful technique for macrophage characterization within the 3D environment of the adipose tissue, enabling the visualization of different macrophage populations and their interaction with other cells within their in vivo niche. Due to the high-fat content and softness, freezing and sectioning of adipose tissue is difficult, and distortion of tissue morphology typically occurs, especially in the case of white adipose tissue. We describe here a whole-mount staining alternative for adipose tissue imaging that preserves all structures and allows high-resolution image acquisition. We address in a step-by-step manner how to perform immunofluorescence staining of different fat pads and how to optimally visualize cellular and acellular (extracellular matrix) constituents of the adipose tissue and its vasculature, as well as resident and infiltrating macrophage populations.

The role of epicardial adipose tissue dysfunction in cardiovascular diseases: an overview of pathophysiology, evaluation, and management

In recent decades, the epicardial adipose tissue (EAT) has been at the forefront of scientific research because of its diverse role in the pathogenesis of cardiovascular diseases (CVDs). EAT lies between the myocardium and the visceral pericardium. The same microcirculation exists both in the epicardial fat and the myocardium. Under physiological circumstances, EAT serves as cushion and protects coronary arteries and myocardium from violent distortion and impact. In addition, EAT acts as an energy lipid source, thermoregulator, and endocrine organ. Under pathological conditions, EAT dysfunction promotes various CVDs progression in several ways. It seems that various secretions of the epicardial fat are responsible for myocardial metabolic disturbances and, finally, leads to CVDs. Therefore, EAT might be an early predictor of CVDs. Furthermore, different non-invasive imaging techniques have been proposed to identify and assess EAT as an important parameter to stratify the CVD risk. We also present the potential therapeutic possibilities aiming at modifying the function of EAT. This paper aims to provide overview of the potential role of EAT in CVDs, discuss different imaging techniques to assess EAT, and provide potential therapeutic options for EAT. Hence, EAT may represent as a potential predictor and a novel therapeutic target for management of CVDs in the future.

Epicardial Adipose Tissue: Clinical Biomarker of Cardio-Metabolic Risk

Epicardial adipose tissue (EAT) is part of the visceral adipose tissue (VAT) that surrounds the heart and it is a quantifiable, modifiable, and multifaceted tissue that has both local and systemic effects. When EAT is enlarged, EAT contributes to atherosclerotic cardiovascular disease (ASCVD) risk and plays a role in the development of metabolic syndrome (MetS). In this review, we will discuss the role of EAT in various facets of MetS, including type 2 diabetes mellitus (T2DM) and insulin resistance. We examine the association between EAT and liver steatosis. We also address the correlations of EAT with HIV therapy and with psoriasis. We discuss racial differences in baseline EAT thickness. We conclude that EAT measurement serves as a powerful potential diagnostic tool in assessing cardiovascular and metabolic risk. Measurement of EAT is made less costly, more convenient, and yet accurate and reliable by transthoracic echocardiography. Furthermore, modification of EAT thickness has therapeutic implications for ASCVD, T2DM, and MetS.

Use and Importance of Nonhuman Primates in Metabolic Disease Research: Current State of the Field

Obesity and its multiple metabolic sequelae, including type 2 diabetes, cardiovascular disease, and fatty liver disease, are becoming increasingly widespread in both the developed and developing world. There is an urgent need to identify new approaches for the prevention and treatment of these costly and prevalent metabolic conditions. Accomplishing this will require the use of appropriate animal models for preclinical and translational investigations in metabolic disease research. Although studies in rodent models are often useful for target/pathway identification and testing hypotheses, there are important differences in metabolic physiology between rodents and primates, and experimental findings in rodent models have often failed to be successfully translated into new, clinically useful therapeutic modalities in humans. Nonhuman primates represent a valuable and physiologically relevant model that serve as a critical translational bridge between basic studies performed in rodent models and clinical studies in humans. The purpose of this review is to evaluate the evidence, including a number of specific examples, in support of the use of nonhuman primate models in metabolic disease research, as well as some of the disadvantages and limitations involved in the use of nonhuman primates. The evidence taken as a whole indicates that nonhuman primates are and will remain an indispensable resource for evaluating the efficacy and safety of novel therapeutic strategies targeting clinically important metabolic diseases, including dyslipidemia and atherosclerosis, type 2 diabetes, hepatic steatosis, steatohepatitis, and hepatic fibrosis, and potentially the cognitive decline and dementia associated with metabolic dysfunction, prior to taking these therapies into clinical trials in humans.

Heterogeneity of white adipose tissue: molecular basis and clinical implications

Adipose tissue is a highly heterogeneous endocrine organ. The heterogeneity among different anatomical depots stems from their intrinsic differences in cellular and physiological properties, including developmental origin, adipogenic and proliferative capacity, glucose and lipid metabolism, insulin sensitivity, hormonal control, thermogenic ability and vascularization. Additional factors that influence adipose tissue heterogeneity are genetic predisposition, environment, gender and age. Under obese condition, these depot-specific differences translate into specific fat distribution patterns, which are closely associated with differential cardiometabolic risks. For instance, individuals with central obesity are more susceptible to developing diabetes and cardiovascular complications, whereas those with peripheral obesity are more metabolically healthy. This review summarizes the clinical and mechanistic evidence for the depot-specific differences that give rise to different metabolic consequences, and provides therapeutic insights for targeted treatment of obesity.

Correlation of epicardial fat and anthropometric measurements in Asian-Indians: A community based study

BACKGROUND:

It is increasingly evident that visceral adipose tissue plays a leading role in the pathogenesis of the metabolic syndrome. Unfortunately, accurate quantification of intra-abdominal visceral fat is cumbersome and expensive. Epicardial fat represents the component of visceral fat distributed around the heart, and is readily and non-invasively assessed by echocardiography.

AIMS:

To determine the correlation of epicardial fat with anthropometric parameters in a healthy population of Asian-Indians.

MATERIALS AND METHODS:

A prospective, cross-sectional study was conducted as part of a community outreach program from December to March 2011. Individuals over 18 years of age were included in the study. Anthropometric data was collected for all patients. Epicardial fat was assessed in parasternal long and short axes.

RESULTS:

350 healthy individuals were included in the study. Of them, 66.7% were males. Mean age was 42.7 ± 15.3 years (range 18-84). Mean body-mass index (BMI) and waist circumference were 23.3 ± 4.5 kg/m² (range 15.2-34.3) and 80.2 ± 13.3 cm (range 43-115) respectively. Mean epicardial fat in both axes was 2.6 ± 1.3 mm (range 0.3-7.0). Epicardial fat measured in both axes correlated well with weight (r = 0.399, P < 0.001), waist circumference (r = 0.522, P < 0.001) and BMI (r = 0.471, P < 0.001). Epicardial fat also correlated with age (r = 0.559, P < 0.001).

CONCLUSIONS:

There is an excellent correlation between epicardial fat measured by echocardiography and anthropometric parameters of metabolic syndrome.

Epicardial fat from echocardiography: a new method for visceral adipose tissue prediction

OBJECTIVE

To validate transthoracic echocardiography as an easy and reliable imaging method for visceral adipose tissue (VAT) prediction. VAT is recognized as an important indicator of high cardiovascular and metabolic risk. Several methods are applied to estimate VAT, with different results.

RESEARCH METHODS AND PROCEDURES

We selected 60 healthy subjects (29 women, 31 men, 49.5 +/- 16.2 years) with a wide range of body mass indexes. Each subject underwent transthoracic echocardiogram and magnetic resonance imaging (MRI) to measure epicardial fat thickness on the right ventricle. Measurements of epicardial adipose tissue thickness were obtained from the same echocardiographic and MRI views and points. MRI was also used to measure VAT cross-sectional areas at the level of L4 to L5. Anthropometric indexes were also measured.

RESULTS

Subjects with predominant visceral fat accumulation showed higher epicardial adipose tissue thickness than subjects with predominant peripheral fat distribution: 9.97 +/- 2.88 vs. 4.34 +/- 1.98 (p = 0.005) and 7.19 +/- 2.74 vs. 3.43 +/- 1.64 (p = 0.004) in men and women, respectively. Simple linear regression analysis showed an excellent correlation between epicardial adipose tissue and waist circumference (r = 0.895, p = 0.01) and MRI abdominal VAT (r = 0.864, p = 0.01). Multiple regression analysis showed that epicardial adipose tissue thickness (r(2) = 0.442, p = 0.02) was the strongest independent variable correlated to MRI VAT. Bland test confirmed the good agreement between the two methods.

DISCUSSION

Epicardial adipose tissue showed a strong correlation with anthropometric and imaging measurements of VAT. Hence, transthoracic echocardiography could be an easy and reliable imaging method for VAT prediction.