At present, several types of modified LDL have been shown to occur in human blood. Curtiss and Witztum15 have demonstrated the presence of nonenzymatically glycosylated LDL in the blood of hyperglycemic diabetic patients. We have recently shown that LDL isolated from the blood of atherosclerotic patients was able to induce intracellular lipid accumulation in cultured aortic cells1617 and differed from native LDL by a lower content of sialic acid; i.e., it appeared to be a desialylated lipoprotein."11,2 Lipoprotein (a), which differs from LDL by the presence of an additional apoprotein is also considered to play an important role in the deposition of intracellular lipids.18"19 In the present study, we demonstrated that in vivo modified LDL caused lipid accumulation in cultured human intimal smooth muscle cells and monocytes. We tested the hypothesis that modified lipoprotein aggregates but not single particles caused intracellular lipid accumulation. To this end we showed that 1) in vivo modified LDLs were able to form aggregates, 2) these aggregates caused the accumulation of cholesteryl esters in cultured cells, and 3) the removal of aggregates from LDL preparation prevented the intracellular cholesteryl ester accumulation. We also attempted to examine the mechanism underlying the interaction between LDL aggregates and vascular cells. Preparation of Lipoproteins LDL (1.019-1.050 g/cm') was isolated by sequential ultracentrifugation in a preparative ultracentrifuge after appropriate adjustment of density with solid NaBr20 from the pooled blood of 12 healthy subjects, from 12 patients with coronary heart disease (CHD) with angiographically documented stenosis of coronary arteries, and from 12 non-insulin-dependent diabetic patients. The degree of lipoprotein aggregation was evaluated by the method based on the analysis of light transmission fluctuations in LDL suspension.29 The relative dispersion of the optical density fluctuations caused by random changes in the number of particles in the optical channel reflects the deviations in their average size, i.e., the degree of aggregation. The optical density fluctuations were measured using a semiconductor laser with collimating optics (wavelength, 860 nm). The aggregate size was determined by methods of quasielastic laser scattering on an Autosizer 2 (Malvern Instrument, UK).For the analysis of lipoprotein aggregation, native and modified lipoproteins were passed through a Sepharose CL-2B column (25 x 0.6 cm) at a flow rate of 0.15 ml/mnin. Fractions (0.30 ml) were collected, and total cholesterol content was determined in each fraction. Examination of Lipoprotein-Lipoprotein InteractionsNinety-six-well microtiter plates were precoated with freshly prepared native and modified lipoproteins (1 ,ug LDL protein per well) and incubated for 1 hour at 37°C. Then the wells were washed with 0.2% bovine serum albumin in PBS, and 0.01-100 ,g/ml`PI-LDL was added to each well. After a 1-hour incubation at 370C, the wells were washed thoroughly with PBS, and radioactivity was...

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The von Willebrand factor (vWF) is a plasma protein that mediates platelet adhesion and leukocyte recruitment to vascular injury sites and carries coagulation factor VIII, a building block of the intrinsic pathway of coagulation. The presence of ultra-large multimers of vWF in the bloodstream is associated with spontaneous thrombosis, whereas its deficiency leads to bleeding. In cardiovascular pathology, the progression of the heart valve disease results in vWF deficiency and cryptogenic gastrointestinal bleeding. The association between higher plasma levels of vWF and thrombotic complications of coronary artery disease was described. Of note, it is not the plasma levels that are crucial for vWF hemostatic activity, but vWF activation, triggered by a rise in shear rates. vWF becomes highly reactive with platelets upon unfolding into a stretched conformation, at shear rates above the critical value (more than 5000 s−1), which might occur at sites of arterial stenosis and injury. The activation of vWF and its counterbalance by ADAMTS-13, the vWF-cleaving protease, might contribute to complications of cardiovascular diseases. In this review, we discuss vWF involvement in complications of cardiovascular diseases and possible diagnostic and treatment approaches.

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Summary: Blood monocytes or intimal smooth muscle cells from normal aorta were incubated with low density lipoprotein (LDL) from patients with coronary atherosclerosis, or with LDL from diabetic patients, or with lipoprotein(a) (Lp(a)). In each case there was a 2-to 4-fold rise in the intracellular cholesteryl ester content. LDL from healthy subjects failed to induce intracellular lipid accumulation in these cells. LDL from patients with coronary atherosclerosis, LDL from diabetic patients, and Lp(a) form aggregates under cell culture conditions. The ability of these lipoproteins to increase the cholesteryl ester content of cultured cells is directly correlated to the degree of lipoprotein aggregation. When aggregates were removed from the lipoprotein preparations by filtration, the latter became less effective in promoting intracellular lipid accumulation. Incubation of cells with lipoprotein aggregates, isolated by gel filtration, induced a 3-to 5-fold elevation of the cellular cholesteryl ester content.These results suggest that LDL from artherosclerotic patients, or LDL from diabetic patients, or Lp(a) have a tendency to form aggregates and that these aggregates are avidly taken up by intimal smooth muscle cells followed by lipid accumulation. This aggregation tendency may play a role in atherogenesis. Introduction. . . -« " u cations in vitro form aggregates under cell culture The accumulation of cholesteryl esters in intimal conditions (11). The degree of aggregation of modified smooth muscle cells is one of the earliest manifesta-LDL is correlated with their ability to increase the tionsof atherosclerosis. Despite intensive investigative intracellular cholesterol ester content. Removal of work, the molecular mechanisms underlying lipid dep-these aggregates from preparations of modified LDL osition within the cells still remain unknown. Native resulted in a marked suppression of lipid accumula-LDL properly isolated from healthy subjects fails to tion in cultured cells. These findings demonstrate that induce intracellular lipid accumulation in cultured the ability of in vitro modified LDL to promote incells (1 -3), while incubation of cells with LDL chem-tracellular lipid deposition depends largely on its agically modified by acetylation, methylation, glyc-gregation. Several types of modified LDL have been ation, oxidation, desialylation, or by malondialde-shown to occur in human blood. Thus Curtiss & hyde, glutaraldehyde or 4-hydroxynonenal treatment Witztum (12) demonstrated the presence of glycresults in deposition of lipid within the cells (1,3, ated LDL in the circulation of hyperglycaemic dia-4 -10). We recently reported that LDL after modifi-betic patients, and recently it was shown that LDL

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C-reactive Protein (CRP) is an acute phase reactant, belonging to the pentraxin family of proteins. Its level rises up to 1000-fold in response to acute inflammation. High sensitivity CRP level is utilized as an independent biomarker of inflammation and cardiovascular disease. The accumulating data suggests that CRP has two distinct forms. It is predominantly produced in the liver in a native pentameric form (nCRP). At sites of local inflammation and tissue injury it may bind to phosphocholine-rich membranes of activated and apoptotic cells and their microparticles, undergoing irreversible dissociation to five monomeric subunits, termed monomeric CRP (mCRP). Through dissociation, CRP deposits into tissues and acquires distinct proinflammatory properties. It activates both classic and alternative complement pathways, binding complement component C1q and factor H. mCRP actively participates in the development of endothelial dysfunction. It activates leukocytes, inducing cytokine release and monocyte recruitment. It may also play a role in the polarization of monocytes and T cells into proinflammatory phenotypes. It may be involved in low-density lipoproteins (LDL) opsonization and uptake by macrophages. mCRP deposits were detected in samples of atherosclerotic lesions from human aorta, carotid, coronary and femoral arteries. mCRP may also induce platelet aggregation and thrombus formation, thus contributing in multiple ways in the development of atherosclerosis and atherothrombosis. In this mini-review, we will provide an insight into the process of conformational rearrangement of nCRP, leading to dissociation, and describe known effects of mCRP. We will provide a rationalization for mCRP involvement in the development of atherosclerosis and atherothrombosis.