Macrophage-derived foam cells freshly isolated from rabbit atherosclerotic lesions degrade modified lipoproteins, promote oxidation of low-density lipoproteins, and contain oxidation-specific lipid-protein adducts.

Abstract

Pure macrophage-derived foam cells (MFC) were isolated from the aortas of rabbits made atherosclerotic by balloon deendothelialization followed by diet-induced hypercholesterolemia. The MFC were isolated under sterile conditions using an enzymatic digestion procedure and discontinuous density gradient centrifugation. The purity of the MFC preparations was verified immunocytochemically with the macrophage specific monoclonal antibody RAM-il. MFC plated in medium containing 0.5% FCS for 24 h contained -600 gg cholesterol per mg cell protein, 80% of which was esterified cholesterol. The MFC specifically degraded low density lipoprotein (LDL), acetyl-LDL, copper oxidized LDL, and beta-very low density lipoprotein (fl-VLDL) at rates comparable to mouse peritoneal macrophages (MPM) in 5-h assays. MFC within sections of the atherosclerotic lesions from the ballooned rabbits as well as the MFC isolated from the same lesions in the presence of antioxidants, exhibited positive immunoreactivity with polyclonal guinea pig antisera and mouse monoclonal antibodies directed against malondialdehyde-LDL, and 4-hydroxynonenal-LDL. The MFC also exhibited the capacity to induce the oxidation of LDL at rates comparable to those exhibited by MPM and rabbit aortic endothelial cells. These data provide direct evidence that arterial wall macrophages express modified LDL receptors in vivo, contain epitopes found in oxidized-LDL and are capable of oxidizing LDL even when maximally loaded with cholesterol. (J. Clin. Invest. 1991. 87:90-99.)

Atherosclerotic plaque characterization by NMR spectroscopy

“…In addition, an extra sample consisting of pure 10% buffered formalin was prepared and it´s NMR spectra was obtained to distinguish the formalin and the zirconium rotor spectra. High resolution 13 C and 1 H NMR experiments were performed at room temperature using a VARIAN INOVA spectrometer operating at 100.5 and 400.0 MHz, respectively, with a 7 mm MAS double-resonance probe. The spinning speed was adjusted at 5 kHz using a pneumatic system in manual mode, which ensures a rotation stability of ± 100 Hz.…”

“…Typical /2 pulses lengths of 3.0 and 3.5 µs were applied to both nuclei. Special care was taken to ensure an optimal signal to noise ratio (S/N) and an approximate number of >2000 and 16 accumulations were used to acquire the 13 The dominant pattern of arteriosclerosis is atherosclerosis, normally characterized by the accumulation of lipids, mainly the cholesterol and cholesteryl esters, inside the intima resulting in thickening and loss of elasticity of arterial walls. Cholesterol (Chol) is a steroid macromolecule derivative from cyclopentane peridrofenantrene, which is composed by four non-planar fused rings, and with an OH group in carbon C19 (see Figure 1a) Figures 1b, c, d and e), in order to compose esters of cholesterol, i.e., cholesteryl esters (CE's).…”

“…Fatty dots and fatty streaks, the earliest indications of atherosclerosis, develop when macrophages and VSMCs are recruited to the intima, where they engulf lipids to form scattered foam cells. Within these initial lesions, the lipids are predominantly in the form of a cholesteryl ester oily phase and a cholesterol-phospholipids liquid crystalline phase [9][10][11][12][13] . At an early stage of atherogenesis, the intimal plaque is formed by the aggregation of multiple foam cells, some of which may have undergone apoptosis and released cellular debris and lipids into the extracellular media.…”

“…We hypothesized that plaque vulnerability to rupture is as direct consequence of lipid alterations and can be detected by variations in 13 C and 1 H spectra patterns. Resonances of Unsaturated Fatty Acids (UFA), Poly Unsaturated Fatty Acids (PUFA), terminal CH 3 carbon of Cholesteryl Ester (CE) and the methine carbons of fatty acids (CH 2 ) n , usually named as "lipid pool", were analyzed in order to provide more quantitative parameters (relative amounts of fatty acids) and how theses parameters are related with atheromatous stability.…”

LDL-cholesterol lowering and atherosclerosis - clinical benefit and possible mechanisms: an update

“…In addition to promoting excess lipid accumulation, oxidised LDL may facilitate the progression of atherosclerotic lesion by disrupting normal endothelial cell function [104]. The finding of oxidised LDL and lipid peroxides in areas of athero sclerotic plaques and the observation that antioxidant treatment with probucol and vitamin E slows the progression of atherosclerosis in the animal model strongly support the role of LDL modification in atherogenesis [105][106][107][108][109]. Recently the results of a randomized, controlled trial of vitamin E in normocholesterolaemic subjects with CAD, the Cambridge Heart Antioxidant Study (CHAOS), were published [110].…”