Accumulation of Plasma-Derived Lipids in the Lipid Core and Necrotic Core of Human Atheroma: Imaging Mass Spectrometry and Histopathological Analyses

Objective: To clarify the pathogenesis of human atheroma, the origin of deposited lipids, the developmental mechanism of liponecrotic tissue, and the significance of the oxidation of phospholipids were investigated using mass spectrometry-aided imaging and immunohistochemistry. Approach and Results: Atherosclerotic lesions in human coronary arteries were divided into 3 groups: pathological intimal thickening with lipid pool, atheroma with lipid core, and atheroma with necrotic core. The lipid pool and lipid core were characterized by the deposition of extracellular lipids. The necrotic core comprised extracellular lipids and liponecrotic tissue. The proportion of cholesteryl linoleate in cholesteryl linoleate+cholesteryl oleate fraction in the extracellular lipid and liponecrotic regions differed significantly from that of the macrophage foam cell–dominant region, and the plasma-derived components (apoB and fibrinogen) were localized in the regions. The liponecrotic region was devoid of elastic and collagen fibers and accompanied by macrophage infiltration in the surrounding tissue. Non–oxidized phospholipid (Non-OxPL), OxPL, and Mox macrophages were detected in the three lesions. In the atheroma with lipid core and atheroma with necrotic core, non-OxPL tended to localize in the superficial layer, whereas OxPL was distributed evenly. Mox macrophages were colocalized with OxPL epitopes. Conclusions: In human atherosclerosis, plasma-derived lipids accumulate to form the lipid pool of pathological intimal thickening, lipid core of atheroma with lipid core, and necrotic core of atheroma with necrotic core. The liponecrotic tissue in the necrotic core appears to be developed by the loss of elastic and collagen fibers. Non-OxPL in the accumulated lipids is oxidized to form OxPL, which may contribute to the lesion development through Mox macrophages.

Spectral Study of the Amphotericin B - cholesteryl Linoleate Interaction

The interaction of amphotericin B with cholesteryl linoleate has investigated by UV-VIS spectroscopy. The binding results have rationalized in terms of methods Benesi-Hildebrand, Scott and Scatchard, taking into account 1:1 amphotericin B - cholesteryl linoleate system.

Effects of LDL, Cholesterol, and Their Oxidized Forms on the Precipitation Kinetics of Calcium Phosphates

Background: LDL, cholesterol, and their oxidized forms are known cardiovascular risk factors and are often found in atherosclerotic lesions of various stages. Little is known, however, about whether they are directly involved in the formation of calcium phosphate compounds. Methods: We used the pH-stat technique to follow the kinetics of calcium phosphate precipitation at pH 7.4, 37 °C, and ionic strength 0.150 mol/L, in the presence or absence of LDL, oxidized LDL, cholesterol, cholestane-3β,5α,6β-triol, and cholesteryl linoleate. The precipitates were characterized by x-ray diffraction, scanning and transmission electronic microscopy coupled with energy-dispersion x-ray analysis, and inductively coupled plasma atomic emission spectroscopy. Results: Under the experimental conditions, LDL (14.8 and 43.1 mg/L protein) had no significant effect on the precipitation kinetics. Oxidized LDL (14.8 and 43.1 mg/L protein) prolonged the nucleation phase and diminished the amount of total precipitate, and both the extent of oxidation and the concentration of the protein affected the kinetics. Cholesterol microcrystals (71.4 and 143 mg/L) made the nucleation phase shorter (300 min vs 390 min for the control), and the precipitated particles had an organic core and a shell composed of calcium phosphates. l-α-Phosphatidylcholine vesicles (143 mg/L), cholesterol (71.4 mg/L)/phospholipid (143 mg/L) mixed vesicles, cholesteryl linoleate (143 mg/L), and cholestane-3β,5α,6β-triol (71.4 mg/L) prolonged the nucleation phase. Conclusions: LDL is not involved directly in the precipitation of calcium phosphates. Oxidized LDL inhibits both nucleation and crystal growth, possibly by attracting calcium ions in the solution and thus reducing supersaturation. Cholesterol microcrystals serve as seeds for the precipitation of hydroxyapatite, whereas l-α-phosphatidylcholine, cholesteryl linoleate, and cholestane-3β,5α,6β-triol exhibit inhibitive effects on the nucleation of calcium phosphates.