Screening for anti-adipogenic, pro-lipolytic and thermogenic plant extracts by models associating intestinal epithelial cells with human adipose cells.

Purpose: Excessive fat mass accumulation in obesity leads to diverse metabolic disorders, increased risks of cardiovascular diseases and in some cases, mortality. The aim of this study was to screen the actions of botanical extracts intended for oral use on human adipose tissue, using an in vitro screening model combining human intestinal cells with human adipose cells. This was to find the most effective extracts on lipid accumulation, UCP1 expression and ATP production in pre-adipocytes and on adipocyte lipolysis.

Increased Basement Membrane Components in Adipose Tissue During Obesity: Links With TGFβ and Metabolic Phenotypes.

Context: Collagen accumulation around adipocytes and vessels (ie, pericellular fibrosis) is a hallmark of obese adipose tissue associated with altered metabolism.

Objective: Our objective was to evaluate components of basement membrane (BM) in adipose tissue, including collagen IV, a major BM component, and its relationships with metabolic parameters and TGFβ isoforms.

Design And Setting: We used immuno-techniques and gene expression approaches to detect BM components in subcutaneous and visceral adipose tissue samples.

Human Adipocytes Induce Inflammation and Atrophy in Muscle Cells During Obesity.

Inflammation and lipid accumulation are hallmarks of muscular pathologies resulting from metabolic diseases such as obesity and type 2 diabetes. During obesity, the hypertrophy of visceral adipose tissue (VAT) contributes to muscle dysfunction, particularly through the dysregulated production of adipokines. We have investigated the cross talk between human adipocytes and skeletal muscle cells to identify mechanisms linking adiposity and muscular dysfunctions.

Human adipocyte function is impacted by mechanical cues.

Fibrosis is a hallmark of human white adipose tissue (WAT) during obesity-induced chronic inflammation. The functional impact of increased interstitial fibrosis (peri-adipocyte fibrosis) on adjacent adipocytes remains unknown. Here we developed a novel in vitro 3D culture system in which human adipocytes and decellularized material of adipose tissue (dMAT) from obese subjects are embedded in a peptide hydrogel.

Endothelial cells from visceral adipose tissue disrupt adipocyte functions in a three-dimensional setting: partial rescue by angiopoietin-1.

During obesity, chronic inflammation of human white adipose tissue (WAT) is associated with metabolic and vascular alterations. Endothelial cells from visceral WAT (VAT-ECs) exhibit a proinflammatory and senescent phenotype and could alter adipocyte functions. We aimed to determine the contribution of VAT-ECs to adipocyte dysfunction related to inflammation and to rescue these alterations by anti-inflammatory strategies.

Semaphorin 3C is a novel adipokine linked to extracellular matrix composition.

Aims/hypothesis: Alterations in white adipose tissue (WAT) function, including changes in protein (adipokine) secretion and extracellular matrix (ECM) composition, promote an insulin-resistant state. We set out to identify novel adipokines regulated by body fat mass in human subcutaneous WAT with potential roles in adipose function.

Methods: Adipose transcriptome data and secretome profiles from conditions with increased/decreased WAT mass were combined.

Roles of chemokine ligand-2 (CXCL2) and neutrophils in influencing endothelial cell function and inflammation of human adipose tissue.

The hypertrophied white adipose tissue (WAT) during human obesity produces inflammatory mediators, including cytokines (IL-6 and TNFα) and chemokines ([C-C motif] chemokine ligand 2 and IL-8). These inflammatory factors are preferentially produced by the nonadipose cells, particularly the adipose tissue infiltrating macrophages. We identified the chemokine (C-X-C motif) ligand 2 (CXCL2) by a transcriptomic approach.

Mast cells in human adipose tissue: link with morbid obesity, inflammatory status, and diabetes.

Aims And Hypothesis: Mast cells are immune cells known for their role in several inflammatory and fibrotic diseases. Recent works in mice suggest that mast cells could be cellular actors involved in the pathophysiology of obesity, a disease characterized by white adipose tissue (WAT) and systemic inflammation. The aim of the study was to better characterize mast cells in WAT of obese with or without type 2 diabetes and lean subjects as well as to explore the relationship with WAT inflammation and fibrosis.

Activin a plays a critical role in proliferation and differentiation of human adipose progenitors.

Objective: Growth of white adipose tissue takes place in normal development and in obesity. A pool of adipose progenitors is responsible for the formation of new adipocytes and for the potential of this tissue to expand in response to chronic energy overload. However, factors controlling self-renewal of human adipose progenitors are largely unknown.

CCL5 promotes macrophage recruitment and survival in human adipose tissue.

Objective: To examine the role of adipose-produced chemokine, chemokine ligand (CCL) 5, on the recruitment and survival of macrophages in human white adipose tissue (WAT).

Methods And Results: CCL5 levels measured by enzyme immunoassay in serum and by real-time polymerase chain reaction in WAT were higher in obese compared to lean subjects. CCL5, but not CCL2, secretion was higher in visceral compared to subcutaneous WAT.

1,2-vinyldithiin from garlic inhibits differentiation and inflammation of human preadipocytes.

Obesity is a state of chronic low-grade inflammation. Limiting white adipose tissue (WAT) expansion and therefore reducing inflammation could be effective in preventing the progression of obesity and the development of associated complications. We investigated the effects of 1,2-vinyldithiin (1,2-DT), a garlic-derived organosulfur, on the differentiation and inflammatory state of human preadipocytes.

Using gene expression to predict the secretome of differentiating human preadipocytes.

Objective: To characterize the secretome of differentiating human preadipocytes using global gene expression profiling.

Design: Gene expression was measured using microarrays at days 0, 1, 3, 5, 7 and 10 in primary preadipocytes undergoing adipogenesis (n=6 independent subjects). Predictive bioinformatic algorithms were employed to identify those differentially expressed genes that code for secreted proteins.

Macrophage-secreted factors promote a profibrotic phenotype in human preadipocytes.

White adipose tissue (WAT) in obese humans is characterized by macrophage accumulation the effects of which on WAT biology are not fully understood. We previously demonstrated that macrophage-secreted factors impair preadipocyte differentiation and induce inflammation, and we described the excessive fibrotic deposition in WAT from obese individuals. Microarray analysis revealed significant overexpression of extracellular matrix (ECM) genes in inflammatory preadipocytes.

Antiadipogenic properties of retinol in primary cultured differentiating human adipocyte precursor cells.

The aim of this study was to investigate the effect of retinol on the human adipose conversion process using primary cultured human adipocyte precursor cells. When these cells were seeded in a medium containing retinol (concentrations ranging from 3.5 nM to 3.

Adipose tissue transcriptomic signature highlights the pathological relevance of extracellular matrix in human obesity.

Background: Investigations performed in mice and humans have acknowledged obesity as a low-grade inflammatory disease. Several molecular mechanisms have been convincingly shown to be involved in activating inflammatory processes and altering cell composition in white adipose tissue (WAT). However, the overall importance of these alterations, and their long-term impact on the metabolic functions of the WAT and on its morphology, remain unclear.

Nongenomic estrogen effects on nitric oxide synthase activity in rat adipocytes.

Estrogens exert multiple genomic effects on adipose tissue through binding to nuclear estrogen receptors. However, there is evidence for additional nongenomic mechanisms whereby estrogens may exert their control on adipose tissue metabolism through rapid activation of various membrane-initiated kinase cascades. Here, we tested rapid effects of estrogens on nitric oxide production in white adipose tissue using 17-beta estradiol (E2) and its membrane impermeant albumin conjugated form (17-beta estradiol hemisuccinate BSA, E2-BSA).

Macrophage-secreted factors impair human adipogenesis: involvement of proinflammatory state in preadipocytes.

Obesity is considered a chronic low-grade inflammatory state. The white adipose tissue produces a variety of inflammation-related proteins whose expression is increased in obese subjects. The nonadipose cell fraction, which includes infiltrated macrophages, is a determinant source of inflammation-related molecules within the adipose tissue.

Cathepsin s promotes human preadipocyte differentiation: possible involvement of fibronectin degradation.

We previously showed that the cysteine protease cathepsin S (CTSS), known to degrade several components of the extracellular matrix (ECM), is produced by human adipose cells and increased in obesity. Because ECM remodeling is a key process associated with adipogenesis, this prompted us to assess the potential role of CTSS to promote preadipocyte differentiation. Kinetic studies in primary human preadipocytes revealed a modest increase in CTSS gene expression and secretion at the end of differentiation.

Weight loss reduces adipose tissue cathepsin S and its circulating levels in morbidly obese women.

Context: Human adipose tissue produces several adipokines, including the newly identified protein cathepsin S (CTSS), a cysteine protease involved in the pathogenesis of atherosclerosis. Obesity is characterized by high levels of CTSS in the circulation and in sc white adipose tissue (scWAT).

Objective: We investigated the effect of surgery-induced weight loss on circulating CTSS and its protein expression in scWAT.

Cholesterol regulation of genes involved in sterol trafficking in human THP-1 macrophages.

Modulation of the expression of genes involved in the control of cholesterol homeostasis by sterols in macrophages is crucial to foam cell formation. To characterize this regulation in THP-1 macrophages, we examined the effect of sterol loading and unloading on the expression of a number of genes that participate in lipoprotein uptake and cholesterol efflux. Sterol loading by exposure to acetylated LDL for 24 h resulted in an increase in free and esterified cholesterol of 1.

Cathepsin S, a novel biomarker of adiposity: relevance to atherogenesis.

The molecular mechanisms by which obesity increases the risk of cardiovascular diseases are poorly understood. The purpose of this study was to identify candidate biomarkers overexpressed in adipose tissue of obese subjects that could link expanded fat mass to atherosclerosis. We compared gene expression profile in subcutaneous adipose tissue (scWAT) of 28 obese and 11 lean subjects using microarray technology.

Monitoring the activation state of the insulin-like growth factor-1 receptor and its interaction with protein tyrosine phosphatase 1B using bioluminescence resonance energy transfer.

We have developed two bioluminescence resonance energy transfer (BRET)-based approaches to monitor 1) ligand-induced conformational changes within partially purified insulin-like growth factor-1 (IGF-1) receptors (IGF1R) and 2) IGF1R interaction with a substrate-trapping mutant of protein tyrosine phosphatase 1B (PTP1B-D181A) in living cells. In the first assay, human IGF1R fused to Renilla reniformis luciferase (Rluc) or yellow fluorescent protein (YFP) were cotransfected in human embryonic kidney (HEK)-293 cells. The chimeric receptors were then partially purified by wheat germ lectin chromatography, and BRET measurements were performed in vitro.

Interaction of PTPB with the insulin receptor precursor during its biosynthesis in the endoplasmic reticulum.

PTP1B is a protein tyrosine-phosphatase predominantly located on the cystosolic surface of the endoplasmic reticulum. This tyrosine-phosphatase plays a major role in the regulation of the activity of the insulin receptor (IR). We have studied the interaction of the IR with PTP1B in living cells using bioluminescence resonance energy transfer (BRET).