Atheroprotective effects of conjugated linoleic acid

Abstract

Atherosclerosis, the underlying cause of heart attack and strokes, is a progressive dyslipidaemic and inflammatory disease where monocyte-derived macrophage cells play a pivotal role. Although most of the mechanisms that contribute to the progression of atherosclerosis have been identified, there is limited information on those governing regression. Conjugated linoleic acid (CLA) is a generic term denoting a group of naturally occurring isomers of linoleic acid (18:2, n6) that differ in the position or geometry (i.e. cis or trans) of their double bonds. The most predominant isomers in ruminant fats are cis-9, trans-11 CLA (c9,t11-CLA), which accounts for more than 80% of CLA isomers in dairy products and trans-10, cis-12 CLA (t10,c12-CLA). Dietary administration of a blend of the two most abundant isomers of CLA has been shown to inhibit the progression and induce the regression of preestablished atherosclerosis. Studies investigating the mechanisms involved in CLA-induced atheroprotective effects are continually emerging. The purpose of this review is to discuss comprehensively the effects of CLA on monocyte/macrophage function in atherosclerosis and to identify possible mechanisms through which CLA mediates its atheroprotective effects. AtherosclerosisAtherosclerosis is a complex inflammatory disease that is characterized by the progressive formation of lipid laden fibrous plaques within the arterial wall [1]. This chronic disease arises from a maladaptive inflammatory response, an impaired resolution process and a defective lipid metabolism [2]. Progressive damage to the vessel wall culminates in arterial occlusion resulting in stenosis or lesion rupture triggering thrombosis. Atherosclerosis is the underlying cause of ischaemic events and often the first clinical manifestation of atherosclerosis is myocardial infarction or stroke [3] The development of the atherosclerotic lesion is initiated by endothelial dysfunction at arterial branch points or locations of altered blood flow [2]. These endothelial alterations facilitate the passage and retention of macromolecules such as LDL molecules within the intima layer [17]. Subsequent oxidation of LDL within the subendothelium by reactive oxygen species (ROS) triggers an inflammatory response [18] characterized by the recruitment of inflammatory cells to the site of endothelial damage. The majority of leukocytes within the developing atherosclerotic lesion are monocytes and macrophages [19]. Oxidized LDL (oxLDL), direct arterial injury, cytokines and growth factors stimulate the secretion of chemokines such as monocyte chemoattractant protein-1 (MCP-1) and interleukin (IL)-8 from endothelial cells, smooth muscle cells and leukocytes [20]. Both MCP-1 and oxLDL recruit monocytes to the vessel wall [18,21].

Hypolipidemic and Hypocholesterolemic Effect of Roselle (<i>Hibiscus sabdariffa</i> L.) Seeds Oil in Experimental Male Rats

“…Substitution of monounsaturated fat or polyunsaturated fat for saturated fat similarly reduces LDL cholesterol but does not reduce HDL or increase triglycerides 10 . Biological studies indicate that conjugated linoleic acid CLA may have salutary effects on the Arteriosclerosis 35 . Rabbits fed for 22 weeks a high fat diet containing conjugated linoleic acid CLA at level of 0.5g CLA/day have achieved significant reductions in total cholesterol, LDL cholesterol, the ratio of LDL-C to HDL-C and in triglyceride concentrations after twelve weeks of the beginning of the experiment 36 .…”

Are nutraceuticals the modern panacea? From myth to science

“…Mechanistic investigation associated with meticulous scrutiny for compounds of potential interest, applying an ethno‐pharmacologic approach, should have a central role in this field of research . Basic research requires an integrated approach that includes investigation of the mechanisms of disease and evaluation of appropriate and meaningful end‐points . To this aim, the use of systemic (omics) approaches with appropriate biomarkers and careful quantification of the bioavailability of the chemical entities of interest has been proposed .…”

Conjugated Linoleic Acid Supplemented Diet Influences Serum Markers in Orchidectomized Sprague‐Dawley Rats

“…Most trials performed on experimental animals use a synthetic mixture of CLA isomers containing mainly c9,t11 ‐CLA and t10,c12 ‐CLA, which are the most biologically relevant. Some of the properties attributed to CLA are its anticarcinogenic, antiatherogenic, antioxidant, and anti‐inflammatory activities; but it has also attracted interest because of its effects on body composition, by reducing body fat and increasing lean mass …”