Peroxisome proliferator-activated receptor gamma; Its role in atherosclerosis and restenosis

Extracellular Vesicles as Drivers of Immunoinflammation in Atherothrombosis

Atherosclerotic cardiovascular disease is the leading cause of morbidity and mortality all over the world. Extracellular vesicles (EVs), small lipid-bilayer membrane vesicles released by most cellular types, exert pivotal and multifaceted roles in physiology and disease. Emerging evidence emphasizes the importance of EVs in intercellular communication processes with key effects on cell survival, endothelial homeostasis, inflammation, neoangiogenesis, and thrombosis. This review focuses on EVs as effective signaling molecules able to both derail vascular homeostasis and induce vascular dysfunction, inflammation, plaque progression, and thrombus formation as well as drive anti-inflammation, vascular repair, and atheroprotection. We provide a comprehensive and updated summary of the role of EVs in the development or regression of atherosclerotic lesions, highlighting the link between thrombosis and inflammation. Importantly, we also critically describe their potential clinical use as disease biomarkers or therapeutic agents in atherothrombosis.

A Citrus bergamia Extract Decreases Adipogenesis and Increases Lipolysis by Modulating PPAR Levels in Mesenchymal Stem Cells from Human Adipose Tissue

The aim of this research was to assess the impact of a well-characterized extract from Citrus bergamia juice on adipogenesis and/or lipolysis using mesenchymal stem cells from human adipose tissue as a cell model. To evaluate the effects on adipogenesis, some cell cultures were treated with adipogenic medium plus 10 or 100 μg/mL of extract. To determine the properties on lipolysis, additional mesenchymal stem cells were cultured with adipogenic medium for 14 days and after this time added with Citrus bergamia for further 14 days. To verify adipogenic differentiation, oil red O staining at 7, 14, 21, and 28 days was performed. Moreover, the expression of peroxisome proliferator-activated receptor gamma (PPAR-γ), adipocytes fatty acid-binding protein (A-FABP), adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), monoglyceride lipase (MGL), 5′-adenosine monophosphate-activated protein kinase (AMPK)α1/2, and pAMPKα1/2 was evaluated by Western blot analysis and the release of glycerol by colorimetric assay. Citrus bergamia extract suppressed the accumulation of intracellular lipids in mesenchymal stem cells during adipogenic differentiation and promoted lipolysis by repressing the expression of adipogenic genes and activating lipolytic genes. Citrus bergamia extract could be a useful natural product for improving adipose mobilization in obesity-related disorders.

Suppression of Adipocyte Differentiation by Foenumoside B from Lysimachia foenum-graecum Is Mediated by PPARγ Antagonism

Lysimachia foenum-graecum extract (LFE) and its active component foenumoside B (FSB) have been shown to inhibit adipocyte differentiation, but their mechanisms were poorly defined. Here, we investigated the molecular mechanisms responsible for their anti-adipogenic effects. Both LFE and FSB inhibited the differentiation of 3T3-L1 preadipocytes induced by peroxisome proliferator-activated receptor-γ (PPARγ) agonists, accompanied by reductions in the expressions of the lipogenic genes aP2, CD36, and FAS. Moreover, LFE and FSB inhibited PPARγ transactivation activity with IC₅₀s of 22.5 μg/ml and 7.63 μg/ml, respectively, and showed selectivity against PPARα and PPARδ. Rosiglitazone-induced interaction between PPARγ ligand binding domain (LBD) and coactivator SRC-1 was blocked by LFE or FSB, whereas reduced NCoR-1 binding to PPARγ by rosiglitazone was reversed in the presence of LFE or FSB. In vivo administration of LFE into either ob/ob mice or KKAy mice reduced body weights, and levels of PPARγ and C/EBPα in fat tissues. Furthermore, insulin resistance was ameliorated by LFE treatment, with reduced adipose tissue inflammation and hepatic steatosis. Thus, LFE and FSB were found to act as PPARγ antagonists that improve insulin sensitivity and metabolic profiles. We propose that LFE and its active component FSB offer a new therapeutic strategy for metabolic disorders including obesity and insulin resistance.

Pterostilbene, a novel natural plant conduct, inhibits high fat-induced atherosclerosis inflammation via NF-κB signaling pathway in Toll-like receptor 5 (TLR5) deficient mice

Atherosclerosis is a specific form of an artery wall thickens, a syndrome affecting arterial blood vessels due to a chronic inflammatory response in the walls of arteries, which is promoted by fat accumulation. Toll-like receptors (TLRs) play prominent roles in inflammatory responses. And TLR5 is overexpressed in several diseases. Here in our study, we investigated the effect of TLR5 in high fat-induced atherosclerosis via NF-κB signaling pathway modulating pro-inflammatory cytokines releasing. Our results found that high fat induced atherosclerosis in wild type mice with fat accumulation and inflammatory response through NF-κB activation. Contrastly, TLR5 knockout mice displayed lower fat accumulation and ameliorated inflammation after high fat feeding with NF-κB inactivation. In addition, pterostilbene, as a natural dimethyl ether derivative of resveratrol mainly from blueberries, has diverse pharmacological activities, especially anti-inflammation. Our study also found that pterostilbene displayed inhibited role in suppressing inflammatory response through inactivating NF-κB signaling pathway regulated by TLR5 down-regulation in high fat-induced mice. Moreover, in vitro experiments of vascular smooth muscle cells (VSMCs) challenged with LPS or TNF-α, further indicated that NF-κB was involved in atherosclerosis progression, leading to high secretion of pro-inflammatory cytokines. However, VSMCs from TLR5 deficient mice inhibited phosphorylated levels of NF-κB signalilng pathway, finally resulting in down-regulation of inflammatory cytokines. Notably, pterostilbene also displayed suppressed role in inflammatory response via NF-κB inactivity in LPS or TNF-α-induced VSMCs by decreasing TLR5 expression. The results above indicated a novel therapeutic strategy of pterostilbene to protect against atherosclerosis via TLR5 regulation for clinic treatment in the future.

Atherosclerosis and tumor suppressor molecules (review)

Atherosclerosis, the major cause of heart attack and stroke, is a chronic inflammatory disease characterized by the formation of atherosclerotic plaque. Oxidized low-density lipoprotein through increased oxidative stress has been identified as one of the primary factors responsible for atherogenesis. Cell proliferation and death are key processes in the progression of atherosclerosis. The oxidative environment in areas of lipid accumulation is mainly created by the production of reactive oxygen species, which are assumed to mediate vascular tissue injury. Oxidative DNA damage and levels of DNA repair are reduced during dietary lipid lowering. The tumor suppressor molecules play a pivotal role in regulating cell proliferation, DNA repair and cell death, which are important processes in regulating the composition of atherosclerotic plaque. Accordingly, in this review, we discuss the fundamental role of tumor suppressor molecules in regulating atherogenesis. In particular, we discuss how tumor suppressor molecules are activated in the complex environment of atherosclerotic plaque, and regulate growth arrest, cell senescence and the apoptosis of vascular smooth muscle cells, which may protect against the progression of atherosclerosis. In addition, we discuss promising alternatives to the use of medications (such as statin) against atherosclerosis, namely diet, with the use of plant-derived supplements to modulate the expression and/or activity of tumor suppressor molecules. We also summarize the progress of research made on herbs with a focus on the modulatory roles of tumor suppressors, and on the molecular mechanisms underlying the prevention if atherosclerosis, supporting designs for further research in this field.

Citrange fruit extracts alleviate obesity-associated metabolic disorder in high-fat diet-induced obese C57BL/6 mouse

Obesity is becoming one of the global epidemics of the 21st century. In this study, the effects of citrange (Citrus sinensis × Poncirus trifoliata) fruit extracts in high-fat (HF) diet-induced obesity mice were studied. Female C57BL/6 mice were fed respectively a chow diet (control), an HF diet, HF diet supplemented with 1% w/w citrange peel extract (CPE) or 1% w/w citrange flesh and seed extract (CFSE) for 8 weeks. Our results showed that both CPE and CFSE regulated the glucose metabolic disorders of obese mice. In CPE and CFSE-treated groups, the body weight gain, blood glucose, serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-c) levels were significantly (p < 0.05) reduced relative to those in the HF group. To explore the mechanisms of action of CPE and CFSE on the metabolism of glucose and lipid, related genes’ expressions in liver were assayed. In liver tissue, the expression level of peroxisome proliferator-activated receptor γ (PPARγ) and its target genes were down-regulated by CPE and CFSE supplementation as revealed by qPCR tests. In addition, both CPE and CFSE decreased the expression level of liver X receptor (LXR) α and β, which are involved in lipid and glucose metabolism. Taken together, these results suggest that CPE and CFSE administration could ameliorate obesity and related metabolic disorders in HF diet-induced obesity mice probably through the inhibition of PPARγ and LXRs gene expressions.

Citrus ichangensis Peel Extract Exhibits Anti-Metabolic Disorder Effects by the Inhibition of PPARγ and LXR Signaling in High-Fat Diet-Induced C57BL/6 Mouse

Obesity is a common nutritional disorder associated with type 2 diabetes, cardiovascular diseases, dyslipidemia, and certain cancers. In this study, we investigated the effects of Citrus ichangensis peel extract (CIE) in high-fat (HF) diet-induced obesity mice. Female C57BL/6 mice were fed a chow diet or an HF diet alone or supplemented with 1% w/w CIE for 8 weeks. We found that CIE treatment could lower blood glucose level and improve glucose tolerance. In the HF+CIE group, body weight gain, serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-c) levels, and liver triglyceride (TG) and TC concentrations were significantly (P < 0.05) decreased relative to those in the HF group. To elucidate the mechanism of CIE on the metabolism of glucose and lipid, related genes expression in liver were examined. In liver tissue, CIE significantly decreased the mRNA expression levels of peroxisome proliferator-activated receptor γ (PPARγ) and its target genes, such as fatty acid synthase (FAS) and acyl-CoA oxidase (ACO). Moreover, CIE also decreased the expression of liver X receptor (LXR) α and β which are involved in lipid and glucose metabolism. These results suggest that CIE administration could alleviate obesity and related metabolic disorders in HF diet-induced obesity mice through the inhibition of PPARγ and LXR signaling.

The role of tanshinone IIA in the treatment of obesity through peroxisome proliferator-activated receptor gamma antagonism

Peroxisome proliferator-activated receptor (PPAR) gamma is a nuclear receptor that coordinates carbohydrate and lipid metabolism, and is a therapeutic target for type 2 diabetes. Tanshinone IIA (Tan) is a lipophilic diterpene that is widely used to treat cardiovascular diseases in traditional Chinese medicine, and has recently been found to reduce body weight and lower blood lipids. However, its underlying mechanism of antiadipogenic effects remains unknown. Here, we report that Tan inhibits 3T3-L1 preadipocyte differentiation and transcriptional activities of full-length PPARgamma and PPARgamma ligand-binding domains. The effects of Tan are mediated through its property as a natural antagonist of PPARgamma (dissociation constant of an inhibitor value, 2.562 +/- 0.711 microm). Tan treatment reduced adipose mass and body weight, improved glucose tolerance, and lowered the low-density lipoprotein to high-density lipoprotein ratio without changing the food intake in a high-fat diet-induced obese animal model. Our results suggest that the combined properties of Tan in adipogenesis, glucose tolerance, lipogenesis, and cardiovascular protection are beneficial for treating diabetic patients with complex metabolic conditions, in which modulating a single target is often not sufficient to achieve the desired effect.