Effects of Ω-3 fatty acids on endothelial function, arterial wall properties, inflammatory and fibrinolytic status in smokers: a cross over study.

BACKGROUND: Smoking is associated with endothelial dysfunction and arterial stiffness. Supplementation of Ω-3 PUFAs is associated with better prognosis. Aim of this study was to evaluate the effects of Ω-3 polyunsaturated fatty acids (PUFAs) supplementation on smoking-induced impairment of arterial function. METHODS: We studied the effect of a 12 weeks oral treatment with 2gr/day of Ω-3 PUFAs in 20 healthy smokers on three occasions (day 0:baseline, day 28 and day 84). The study was carried out on two separate arms (Ω-3 fatty acids and placebo), according to a randomized, placebo-controlled, double-blind, cross-over design. Measurements were carried out before (pSm), immediately and 20min after cigarette smoking. Endothelial function was evaluated by flow-mediated dilation (FMD) of the brachial artery. Carotid-femoral pulse wave velocity (PWV) was measured as an index of aortic stiffness and augmentation index (AIx) as a measure of arterial wave reflections. Circulating levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and plasminogen activator inhibitor-1 (PAI-1) were measured. RESULTS: Compared with placebo, Ω-3 PUFAs treatment resulted in a significant improvement in pSm values of FMD (p<0.05), AIx (p<0.001) and PWV (p<0.01). Although, acute cigarette smoking decreased FMD and caused an increase in AIx and PWV, Ω-3 PUFAs treatment blunted the acute smoking-induced impairment of FMD (p<0.001), AIx (p<0.05) and PWV (p<0.05) and significantly decreased levels of TNFα (p<0.05) and IL-6 (p=0.01) and increased levels of PAI-1 (p=0.05). CONCLUSIONS: Ω-3 PUFAs improved endothelial function and the elastic properties of the arterial tree in healthy smokers, with a parallel anti-inflammatory effect.

Inflammatory mechanisms in atherosclerosis: the impact of matrix metalloproteinases.

Inflammatory process is essential for the initiation and progression of vascular remodeling, entailing degradation and reorganization of the extra-cellular matrix (ECM) scaffold of the vessel wall, leading to the development of atherosclerotic lesions. Matrix metalloproteinases (MMPs) are zing dependent endo-peptidases found in most living organisms and act mainly by degrading ECM components. Most MMPs are formed as inactive proenzymes and are activated by proteolysis. This process depends and is regulated by other proteases and endogenous MMP inhibitors (TIMPs). MMPs and TIMPs play a major role not only in ECM degradation but also in mediating cell migration, proliferation, tissue remodeling; acting as a signal for the production and secretion of growth factors and cytokines. More importantly MMPs through proteolysis and degradation of ECM contribute in many physiological and pathological processes including organ development, wound healing, tissue support, vascular remodeling and restenosis, atherosclerosis progression, acute coronary syndromes, myocardial infarction, cardiomyopathy, aneurysms remodeling, cancer, arthritis, and chronic inflammatory diseases. A substantial body of evidence support the notion that imbalance between the activity of MMPs and their tissue inhibitors (TIMPs) contribute to the pathogenesis of cardiovascular diseases such as atherosclerosis, vascular remodeling and progression of heart failure. In this review, we will discuss the relationship between MMPs, inflammation and atherosclerosis under the topic of cardiovascular disease.

The impact of oral L-arginine supplementation on acute smoking-induced endothelial injury and arterial performance.

BACKGROUND: Smoking is associated with endothelial dysfunction and increased inflammatory status. The amino acid L-arginine, improves endothelial function in patients with cardiovascular risk factors. We investigated the effect of L-arginine on vascular function and inflammatory process in healthy smokers at rest and after acute smoking. METHODS: We studied the effect of L-arginine and/or placebo in 12 healthy young smokers on three occasions (day 0, day 1, and day 3). The study was carried out on two separate arms, one with L-arginine (3 x 7 g/day) and one with placebo, according to a randomized, placebo-controlled, double-blind, cross-over design. Measurements were carried out before, immediately after, and 20 min after cigarette smoking. Endothelial function was evaluated by flow-mediated dilation (FMD). Carotid-femoral pulse wave velocity (PWV) was measured as an index of aortic stiffness and augmentation index (AIx) and as a measure of arterial wave reflections. Serum soluble intercellular adhesion molecule-1 (sICAM-1) was measured. RESULTS: Compared to placebo, L-arginine improved FMD (P < 0.01 at day 1 and P < 0.05 at day 3). L-Arginine reduced PWV and AIx at both days 1 and 3 (P < 0.05 vs. baseline). L-Arginine blunted the acute smoking-induced increase of AIx at both day 1 (P < 0.05) and day 3 (P < 0.01), and prevented the smoking-induced elevation of PWV at day 3 (P < 0.05). Importantly, L-arginine reduced sICAM-1 at days 1 and 3 (P < 0.05 for both vs. baseline). CONCLUSIONS: Oral L-arginine improves endothelial function and vascular elastic properties of the arterial tree during the acute phase of smoking, an effect accompanied by reduced sICAM-1 levels in these subjects.

Shear stress, protein kinases and atherosclerosis.

Shear stress represents the frictional force that the flow of blood exerts at the endothelial surface of the vessel wall and plays a central role in cell function and structure via managing several processes and contributes to the progress of atherosclerosis. It is a fact that interaction of blood flow and the endothelial surface is the critical interface for shear stress-dependent mechanotransduction. Vascular endothelial cells are equipped with numerous receptors in order to "sense" and react to mechanical forces elicited by shear stress. The intracellular signal transduction pathways and specifically the activation of protein kinases, is the second important molecular event underpinning cellular reactions to extracellular stimuli. MAPKs, comprising ERK1/2, JNKs/stress-activated protein kinases (SAPKs), and p38s, are serine/threonine protein kinases with a prominent role in cell differentiation, growth, and apoptosis, by modulating the activity of downstream target proteins and various transcription factors, hence gene expression programs. Shear stress (nonlaminar or disturbed blood flow) plays an important role in atherosclerosis, where flow conditions are characterized by low or oscillatory shear stress. Atherosclerosis is promoted by decreased shear stress, as it is associated with a suppression of functions taking place on the vascular wall, such as eNOs production and endothelial cell repair. In the presence of systemic risk factors, there is an increased tendency for atherosclerotic plaque formation, which, once formed, further disrupt flow and forward growth of the fibroinflammatory lipid plaque. Targeted inhibition of many kinase types and subtypes is an immense research field as this may lead to novel therapeutic approaches to prevent atherogenesis.