The endothelium is a key constituent of the vascular wall, being actively involved in maintaining the structural integrity and proper functioning of blood vessels. Hyperlipidemia, diabetes, hypertension, smoking and aging are important risk factors for the dysfunction of endothelial cells (EC). Circulating lipoproteins (Lp) synthesized and secreted from the intestine or liver have an important role in supplying peripheral tissues with fatty acids from triglyceride rich lipoproteins (TGRLp) for energy production or storage, and cholesterol from low density lipoproteins (LDL) or high density lipoproteins (HDL) for the synthesis of cellular membranes and steroid hormones. Under pathological conditions, Lp may suffer alterations in concentration and composition and become aggressors for EC. Modified LDL, remnant Lp, TGRLp lipolysis products, dysfunctional HDL are involved in the changes induced in EC morphology (reduced glycocalyx, overdeveloped endoplasmic reticulum, Golgi apparatus and basement membrane), loose intercellular junctions, increased oxidative and inflammatory stress, nitric oxide/redox imbalance, excess Lp transport and storage, as well as loss of anti-thrombotic properties, all of these being characteristics of endothelial dysfunction. Normal HDL are able to counteract the harmful effects of atherogenic Lp in EC but under persistent pathological conditions they lose the protective properties and become pro-atherogenic. This review summarises recent advances in understanding the role of Lp in the induction of endothelial dysfunction and the initiation and progression of atherosclerotic lesions. Its main focus is the antagonistic role of atherogenic Lp (LDL, VLDL, dysfunctional HDL) versus anti-atherogenic Lp (HDL), also pointing out the potential targets for arresting or reversing this process.

There is a stringent need to find means for risk stratification of coronary artery diseases (CAD) patients. We aimed at identifying alterations of plasma high-density lipoproteins (HDL) components and their validation as dysfunctional HDL that could discriminate between acute coronary syndrome (ACS) and stable angina (SA) patients. HDL2 and HDL3 were isolated from CAD patients’ plasma and healthy subjects. ApolipoproteinAI (apoAI), apoAII, apoCIII, malondialdehyde (MDA), myeloperoxidase (MPO), ceruloplasmin and paraoxonase1 (PON1) were assessed. The anti-inflammatory potential of HDL subfractions was tested by evaluating the secreted inflammatory molecules of tumor necrosis factor α-activated endothelial cells (EC) upon co-incubation with HDL2 or HDL3. We found in ACS versus SA patients: 40% increased MPO, MDA, apoCIII in HDL2 and HDL3, 35% augmented apoAII in HDL2, and in HDL3 increased ceruloplasmin, decreased apoAII (40%) and PON1 protein and activity (15% and 25%). Co-incubation of activated EC with HDL2 or HDL3 from CAD patients induced significantly increased levels of secreted inflammatory molecules, 15–20% more for ACS versus SA. In conclusion, the assessed panel of markers correlates with the reduced anti-inflammatory potential of HDL subfractions isolated from ACS and SA patients (mostly for HDL3 from ACS) and can discriminate between these two groups of CAD patients.

Atherosclerosis is the main process behind cardiovascular diseases (CVD), maladies which continue to be responsible for up to 70% of death worldwide. Despite the ongoing development of new and potent drugs, their incomplete efficacy, partial intolerance and numerous side effects make the search for new alternatives worthwhile. The focus of the scientific world turned to the potential of natural active compounds to prevent and treat CVD. Essential for effective prevention or treatment based on phytochemicals is to know their mechanisms of action according to their bioavailability and dosage. The present review is focused on the latest data about phenolic compounds and aims to collect and correlate the reliable existing knowledge concerning their molecular mechanisms of action to counteract important risk factors that contribute to the initiation and development of atherosclerosis: dyslipidemia, and oxidative and inflammatory-stress. The selection of phenolic compounds was made to prove their multiple benefic effects and endorse them as CVD remedies, complementary to allopathic drugs. The review also highlights some aspects that still need clear scientific explanations and draws up some new molecular approaches to validate phenolic compounds for CVD complementary therapy in the near future.In the last decade the scientific researchers turned their attention to phytochemicals, as effective, safe and low-cost natural bioactive compounds for CVD treatment.Dyslipidemia consists of increased blood concentrations of total cholesterol (TC), low density lipoproteins-cholesterol (LDL-C) and/or triglycerides (TG), and decreased high density lipoproteins-cholesterol (HDL-C) [6]. The lipid metabolism is complex and the candidate mechanisms that could generate dyslipidemia include: (i) excessive dietary lipid absorption in the small intestine; (ii) packing of exogenous lipids with cholesterol and fatty acids produced de novo in the liver and their secretion as very low density lipoproteins (VLDL); (iii) hydrolysis of TG from VLDL by lipases and their conversion into LDL, which are taken up by the peripheral tissues through LDL receptor (LDL-R) and scavenger receptors; (iv) diminished production of HDL by the liver and small intestine, thereby decreasing reverse cholesterol transport (RCT) from the peripheral tissues to the liver; (v) lowered excess cholesterol excretion from the liver into gallbladder or to the intestinal lumen through the ATP-binding cassette G5 and G8 transporters (ABCG5/G8) that facilitate trans-intestinal cholesterol efflux (TICE). Dyslipidemia is associated with the accumulation of LDL in the sub-endothelium of the artery wall. At this site, LDL undergoes oxidative modifications (oxLDL) that trigger inflammatory responses, and is taken up by the monocyte-derived macrophages infiltrated in the sub-endothelium which thus become lipid-loaded foam cells, the hallmark of atheroma development [7]. Until now, the most effective lipid-lowering treatment for hyperlipidemic patients was the statin therapy. But recen...

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Type 2 Diabetes Mellitus is a worldwide epidemic, and its atherosclerotic complications produce morbidity and mortality in affected patients. It is known that the vascular cell adhesion molecule-1 (VCAM-1) levels are increased in the sera of diabetic patients. Our aim was to investigate the impact of the endoplasmic reticulum stress (ERS) in VCAM-1 expression and secretion in human endothelial cells (HEC) exposed to glycated low-density lipoproteins (gLDL). The results showed that 24 h incubation of HEC with gLDL induces (i) stimulation of VCAM-1 expression and secretion, determining increased monocyte adhesion to HEC; (ii) RAGE up-regulation and free cholesterol loading; (iii) ERS activation (increased eIF2α phosphorylation and CHOP mRNA levels, and decreased GRP78 protein expression); and (iv) oxidative stress [increased levels of reactive oxygen species (ROS) and glutamate cysteine ligase catalytic unit gene expression]. Treatment of gLDL-exposed HEC with ERS inhibitors, salubrinal (Sal) and sodium phenylbutyrate (PBA), decreased intracellular ROS. Incubation of gLDL-exposed cells with the anti-oxidant N-acetyl-cysteine (NAC) reduced ERS, revealed by decreased eIF2α phosphorylation and CHOP gene expression and increased GRP78 expression, thus validating the interconnection between ERS and oxidative stress. Sal, PBA, NAC and inhibitors of p38 MAP kinase and NF-kB induced the decrease of VCAM-1 expression and of the ensuing monocyte adhesion induced by gLDL. In conclusion, in HEC, gLDL stimulate the expression of cellular VCAM-1, the secretion of soluble VCAM-1, and the adhesion of monocytes through mechanisms involving p38 MAP kinase and NF-kB signalling pathways activated by RAGE, ERS and oxidative stress, thus contributing to diabetic atherosclerosis.