Triacylglycerol-rich lipoproteins interact with human vascular cells in a lipid-dependent fashion

New insight into dyslipidemia‐induced cellular senescence in atherosclerosis

Atherosclerosis, characterized by lipid‐rich plaques in the arterial wall, is an age‐related disorder and a leading cause of mortality worldwide. However, the specific mechanisms remain complex. Recently, emerging evidence has demonstrated that senescence of various types of cells, such as endothelial cells (ECs), vascular smooth muscle cells (VSMCs), macrophages, endothelial progenitor cells (EPCs), and adipose‐derived mesenchymal stem cells (AMSCs) contributes to atherosclerosis. Cellular senescence and atherosclerosis share various causative stimuli, in which dyslipidemia has attracted much attention. Dyslipidemia, mainly referred to elevated plasma levels of atherogenic lipids or lipoproteins, or functional impairment of anti‐atherogenic lipids or lipoproteins, plays a pivotal role both in cellular senescence and atherosclerosis. In this review, we summarize the current evidence for dyslipidemia‐induced cellular senescence during atherosclerosis, with a focus on low‐density lipoprotein (LDL) and its modifications, hydrolysate of triglyceride‐rich lipoproteins (TRLs), and high‐density lipoprotein (HDL), respectively. Furthermore, we describe the underlying mechanisms linking dyslipidemia‐induced cellular senescence and atherosclerosis. Finally, we discuss the senescence‐related therapeutic strategies for atherosclerosis, with special attention given to the anti‐atherosclerotic effects of promising geroprotectors as well as anti‐senescence effects of current lipid‐lowering drugs.

Effects of Virgin Olive Oil and Phenol-Enriched Virgin Olive Oils on Lipoprotein Atherogenicity

The atherogenicity of low-density lipoprotein (LDL) and triglyceride-rich lipoproteins (TRLs) may be more significant than LDL cholesterol levels. Clinical trials which have led to increased high-density lipoprotein (HDL) cholesterol have not always seen reductions in cardiovascular disease (CVD). Furthermore, genetic variants predisposing individuals to high HDL cholesterol are not associated with a lower risk of suffering a coronary event, and therefore HDL functionality is considered to be the most relevant aspect. Virgin olive oil (VOO) is thought to play a protective role against CVD. This review describes the effects of VOO and phenol-enriched VOOs on lipoprotein atherogenicity and HDL atheroprotective properties. The studies have demonstrated a decrease in LDL atherogenicity and an increase in the HDL-mediated macrophage cholesterol efflux capacity, HDL antioxidant activity, and HDL anti-inflammatory characteristics after various VOO interventions. Moreover, the expression of cholesterol efflux-related genes was enhanced after exposure to phenol-enriched VOOs in both post-prandial and sustained trials. Improvements in HDL antioxidant properties were also observed after VOO and phenol-enriched VOO interventions. Furthermore, some studies have demonstrated improved characteristics of TRL atherogenicity under postprandial conditions after VOO intake. Large-scale, long-term randomized clinical trials, and Mendelian analyses which assess the lipoprotein state and properties, are required to confirm these results.

Membrane composition and dynamics: a target of bioactive virgin olive oil constituents

The endogenous synthesis of lipids, which requires suitable dietary raw materials, is critical for the formation of membrane bilayers. In eukaryotic cells, phospholipids are the predominant membrane lipids and consist of hydrophobic acyl chains attached to a hydrophilic head group. The relative balance between saturated, monounsaturated, and polyunsaturated acyl chains is required for the organization and normal function of membranes. Virgin olive oil is the richest natural dietary source of the monounsaturated lipid oleic acid and is one of the key components of the healthy Mediterranean diet. Virgin olive oil also contains a unique constellation of many other lipophilic and amphipathic constituents whose health benefits are still being discovered. The focus of this review is the latest evidence regarding the impact of oleic acid and the minor constituents of virgin olive oil on the arrangement and behavior of lipid bilayers. We highlight the relevance of these interactions to the potential use of virgin olive oil in preserving the functional properties of membranes to maintain health and in modulating membrane functions that can be altered in several pathologies. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Endothelial cells as targets for chylomicron remnants

Endothelial dysfunction is characterised by pro-inflammatory/pro-coagulant changes in the endothelium and supports leukocyte adhesion and transmigration, key steps in early atherogenesis. There is emerging evidence that triacylglycerol-rich lipoproteins (TGRLs) present in the circulation during the postprandial phase influence vascular inflammation but the specific contribution of the remnant lipoprotein component of TGRLs is largely unexplored and the mechanistic basis of their actions poorly defined. This article provides a brief overview of the evidence supporting direct actions of these particles on endothelial cells and highlights the importance of their fatty acid composition and oxidative state as determinants of their cellular actions.

Triacylglycerol-rich lipoproteins trigger the phosphorylation of extracellular-signal regulated kinases in vascular cells

Postprandial triacylglycerol-rich lipoproteins (TRL) have been implicated in the pathophysiology of atherosclerosis, but the intracellular processes by which TRL could affect vascular function are still unknown. Incubation of TRL obtained at 2 h postprandial period with vascular smooth muscle cells (VSMC) produced a tyrosine phosphorylation of the extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2) that belong to the mitogen-activated protein kinase (MAPK) family. The activation of ERK1 and ERK2 had a maximum at 15 min, returned to baseline by 60 min, and was partially depleted after incubation of cells with a MAPKK inhibitor (PD 098059). In addition, postprandial TRL did competent VSMC for DNA replication through a MAPK pathway. These effects were dependent of the lipid composition of TRL. Our observations suggest that postprandial TRL can trigger activation of the MAPK pathway and induce a mitogenic response in VSMC in a lipid-dependent fashion.