Genetic deletion of platelet glycoprotein Ib alpha but not its extracellular domain protects from atherosclerosis.

The pathogenesis of atherosclerosis involves the interplay of haematopoietic, stromal and endothelial cells. Platelet interactions with endothelium and leukocytes are pivotal for atherosclerosis promotion. Glycoprotein (GP) Ibα is the ligand-binding subunit of the platelet GPIb-IX-V receptor complex; its deficiency causes the Bernard-Soulier syndrome (BSS), characterised by absent platelet GPIb-IX-V, macrothrombocytopenia and bleeding. We designed this study to determine the role of platelet GPIbα in the pathogenesis of atherosclerosis using two unique knockout models. Ldlr-/- mice were reconstituted with wild-type (wt), GPIbα-/- (lacks GPIbα) or chimeric IL-4R/GPIbα-Tg (lacks GPIbα extracellular domain) bone marrow and assayed for atherosclerosis development after feeding with pro-atherogenic "western diet". Here, we report that Ldlr-/-mice reconstituted with GPIbα-/- bone marrow developed less atherosclerosis compared to wt controls; accompanied by augmented accumulation of pro-inflammatory CD11b+ and CD11c+ myeloid cells, reduced oxLDL uptake and decreased TNF and IL 12p35 gene expression in the aortas. Flow cytometry and live cell imaging in whole blood-perfused microfluidic chambers revealed reduced platelet-monocyte aggregates in GPIbα-/- mice, which resulted in decreased monocyte activation. Interestingly, Ldlr-/-mice reconstituted with IL-4R/GPIbα-Tg bone marrow, producing less abnormal platelets, showed atherosclerotic lesions similar to wt mice. Platelet interaction with blood monocytes and accumulation of myeloid cells in the aortas were also essentially unaltered. Moreover, only complete GPIbα ablation altered platelet microparticles and CCL5 chemokine production. Thus, atherosclerosis reduction in mice lacking GPIbα may not result from the defective GPIbα-ligand binding, but more likely is a consequence of functional defects of GPIbα-/- platelets and reduced blood platelet counts.

In vitro neutron irradiation of glioma and endothelial cultured cells.

To fully develop its potential boron neutron capture therapy (BNCT) requires the combination of a suitable thermal/epithermal neutron flux together with a selective intake of (10)B-boron nuclei in the target tissue. The latter condition is the most critical to be realized as none of the boron carriers used for experimental or clinical purposes proved at the moment an optimal selectivity for cancer cells compared to normal cells. In addition to complex physical factors, the assessment of the intracellular concentration of boron represent a crucial parameter to predict the dose delivered to the cancer cells during the treatment. Nowadays the dosimetry calculation and then the prediction of the treatment effectiveness are made using Monte Carlo simulations, but some of the model assumption are still uncertain: the radiobiological dose efficacy and the probability of tumour cell survival are crucial parameters that needs a more reliable experimental approach. The aim of this work was to evaluate the differential ability of two cell lines to selectively concentrate the boron-10 administered as di-hydroxyboryl-phenylalanine (BPA)-fructose adduct, and the effect of the differential boron intake on the damage produced by the irradiation with thermal neutrons; the two cell lines were selected to be representative one of normal tissues involved in the active/passive transport of boron carriers, and one of the tumour. Recent in vitro studies demonstrated how BPA is taken by proliferating cells, however the mechanism of BPA uptake and the parameters driving the kinetics of influx and the elimination of BPA are still not clarified. In these preliminary studies we analysed the survival of F98 and human umbilical vein endothelial cells (HUVEC) cells line after irradiation, using different thermal fluencies at the same level of density population and boron concentration in the growing medium prior the irradiation. This is first study performed on endothelium model obtained by a primary human cell line (HUVEC). The perspective application of this work is to develop a model able to foresee the effects produced by different combination of boron influx with a thermal neutron fluencies, applying a standardized radiobiological methodology, and in particular to continue the investigation of the radiobiological effects on the endothelium model as the main tissue involved in the transport of boronated molecules.

n-3 fatty acids: antiatherosclerotic effects.

The low incidence of cardiovascular disease associated epidemiologically with high consumption of food rich in n-3 fatty acids suggests the possibility that part of the beneficial cardiovascular effects of these natural substances may be due to a reduction of atherosclerosis. This has been recently confirmed in autoptic data and in at least one prospective trial evaluating the progression of coronary atherosclerosis in humans. This paper reviews published literature on n-3 fatty acids and atherosclerosis in animal models and in humans and in vitro experimental data yielding suport to the hypothesis of antiatherosclerotic effects of these substances.

Inhibition of endothelial cell activation by nitric oxide donors.

Because nitric oxide (NO) inhibits the expression of endothelial leukocyte adhesion molecules, NO-generating compounds have major therapeutic potential for use outside their classical indications. We report on the in vitro potential antiatherogenicity of two novel cysteine-containing NO donors, SP/W 3672, a fast spontaneous NO releaser, and its prodrug SP/W 5186, which liberates NO after bioactivation. The ability of these two compounds to inhibit monocyte adhesion and surface expression of endothelial adhesion molecules was evaluated and compared with that of other NO donors. SP/W 5186 and SP/W 3672 inhibited the adhesion of U937 monocytes to cultured human endothelial cells more potently than S-nitrosoglutathione (GSNO) or spermine NONOate, whereas nitroglycerin and isosorbide dinitrate were ineffective at comparable concentrations. A similar rank order of potency was found for the inhibition of expression of the adhesion molecules vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and E-selectin as well as for major histocompatibility complex class II antigen expression. Estimated IC(50) values for vascular cell adhesion molecule-1 were >400 microM for SP/W 4744 (control for SP/W 3672 lacking the cysteine moiety), 200 microM for GSNO and spermine NONOate, 80 microM for SP/W 3672, and 50 microM for SP/W 5186. Moreover, SP/W 5186 inhibited VCAM-1 mRNA levels more potently than GSNO. This effect was likely to be transcriptional because mRNA degradation was not affected. In conclusion, SP/W 3672 and SP/W 5186 are novel potent inhibitors of endothelial activation, and this effect appears to relate to their ability to liberate NO for prolonged periods of time, either spontaneously or after conversion to active hydrolytic products.

[Hyperhomocysteinemia and vascular disease]. / Iperomocisteinemia e malattia vascolare.

Hyperhomocysteinemia, the pathological increase of plasma homocysteine concentrations, is gaining increased attention in atheroscierosis research. Reasons for the wide present interest for this disorder of metabolism are that it may account, in the hereditary heterozygous and the acquired forms, for a still undetermined but possibly very large number of clinical manifestations of atheroscierosis in the adult population; and that the current understanding of the mechanisms by which high plasma concentrations of homocysteine induce vascular damage is presently to a large extent incomplete. As indicated by several lines of evidence, the endothelial cell appears to be the main target for the sustained toxic aggression by hyperomocysteinemia, possibly through the generation of an enhanced oxidative stress. A better understanding of the causes and mechanisms of homocysteine-induced vascular damage will likely lead to the development of better targeted preventive and therapeutical approaches in vascular disease.