These results suggest that the combination of matrix glycation and inflammation up-regulates the activation of the endothelial cell adhesion cascade, a mechanism that might contribute to the increased burden of atherosclerotic morbidity and mortality in patients suffering from diabetes mellitus or chronic renal failure.

Abstract. Although iron sucrose and iron gluconate are generally well tolerated in patients who are treated for renal anemia, recent clinical studies and cell culture experiments suggested significant toxicity and long-term side effects arising from the use of these iron complexes. Because of the possible role of iron in infection or cardiovascular disease, it was theorized that parenteral iron compounds influence endothelial and PMN interaction in vitro. A well-established double-chamber method was used to assess the effect of different concentrations of iron sucrose and iron gluconate (1, 25, 50, and 100 g/ml) on the transendothelial migration of PMN. Preincubation of PMN and endothelial cells as well as preincubation of PMN alone with 25, 50, or 100 g/ml iron resulted in a significant decrease in PMN migration. In contrast, after incubation of the endothelial cells alone with iron, no reduction in the transendothelial migration of PMN was observed. Preincubation of PMN and/or endothelial cells with 1 g/ml iron did not lead to any decrease in the rate of migrated PMN. The only significant change in experiments with 1 g/ml was an increase in PMN migration after preincubation of endothelial cells and PMN with iron gluconate. A four-way ANOVA showed a significant effect of the iron concentration (P Ͻ 0.000001), of type of iron complex (P Ͻ 0.005), of the preincubation of endothelial cell (P Ͻ 0.001), and of the preincubation of PMN with iron (P Ͻ 0.000001) on PMN diapedesis. It is concluded that iron sucrose and iron gluconate cause a significant inhibition of transendothelial migration of PMN.Renal anemia therapy requires an intravenous iron substitution in addition to the erythropoietin therapy in the majority of patients (1). Iron substitution not only reduces the erythropoietin dosage needed but also is necessary to maintain the target hemoglobin above 11 g/dl (2,3). There are several iron preparations for intravenous use available, all of which have potential side effects, such as allergic reactions, cell injury, or endothelial dysfunction (4 -7). Moreover, iron therapy may be associated with infectious complications and with loss of the ability of patient serum to resist the bacterial growth (8 -10). PMN play a vital role in the nonspecific immune reaction against bacterial infections executing functions such as chemotaxis, transendothelial migration, phagocytosis, and intracellular killing by proteolytic enzymes or toxic oxygen radicals. Although the effects of iron on chemotaxis of PMN, phagocytosis, and intracellular killing in PMN were studied previously, the effect of iron complexes on PMN-endothelial cell interaction is unknown. Therefore, we examined the effect of incubation of PMN and/or endothelial cells with two widely used iron complexes, iron(III)-hydroxide-sucrose complex (iron sucrose) and iron(III)-sodium-gluconate in sucrose (iron gluconate), on the PMN migration through the endothelium in an in vitro setting.

No abstract

. A SAGEbased comparison between glomerular and aortic endothelial cells.

The oxidative modification of LDL may play a significant role in atherogenesis. Myeloperoxidase (MPO) expressed in human atherosclerotic plaques has been suggested to be operative in vivo, making LDL atherogenic. Tyrosyl radicals generated by MPO have been shown to act as physiological pro-oxidants of lipid peroxidation in LDL. Assuming that a variety of phenolic compounds are able to form phenoxyl radicals when exposed to peroxidases, we tested the ability of paracetamol, a known analgesic drug with a tyrosine-like monophenolic structure, to act as a pro-oxidant of lipid peroxidation in LDL. Spectroscopic analyses indicated that paracetamol, similar to tyrosine, could undergo peroxidase-induced phenoxyl radical formation, which was inhibited by the radical scavenger ascorbic acid as well as by heme poisons and catalase. Measurement of conjugated dienes and lipid hydroperoxides in LDL preparations exposed to MPO/H2O2 in the absence or presence of paracetamol revealed that the drug could act as a catalyst of lipid oxidation in LDL. Similar results were found when LDL oxidation was performed with activated human neutrophils, which use MPO to promote lipid peroxidation. In conclusion, the results suggest that paracetamol could act, via a phenoxyl radical, as a catalyst of LDL oxidative modification by MPO.

No abstract

SummaryRecent data suggest that auricular thrombosis is associated with accumulation of mast cells (MC) in the upper endocardium (where usually no MC reside) and local expression of MGF (mast cell growth factor) (25). In this study, the role of vascular cells, thrombin-activation and MGF, in MC-migration was analyzed. For this purpose, cultured human auricular endocardial cells (HAUEC), umbilical vein endothelial cells (HUVEC) and uterine-(HUTMEC) and skin-derived (HSMEC) microvascular endothelial cells were exposed to thrombin or control medium, and the migration of primary tissue MC (lung, n = 6) and HMC-1 cells (human MC-line) against vascular cells (supernatants) measured. Supernatants (24 h) of unstimulated vascular cells (monolayers of endocardium or endothelium) as well as recombinant (rh) MGF induced a significant migratory response in HMC-1 (control: 3025 ± 344 cells [100 ± 11.4%] vs. MGF, 100 ng/ml: 8806 ± 1019 [291 ± 34%] vs. HAUEC: 9703 ± 1506 [320.8 ± 49.8%] vs. HUTMEC: 8950 ± 1857 [295.9 ± 61.4%] vs. HSMEC: 9965 ± 2018 [329.4 ± 66.7%] vs. HUVEC: 9487 ± 1402 [313.6 ± 46.4%], p <0.05) as well as in primary lung MC. Thrombin-activation (5 U/ml, 12 h) of vascular cells led to an augmentation of the directed migration of MC as well as to a hirudin-sensitive increase in MGF synthesis and release. Moreover, a blocking anti-MGF antibody was found to inhibit MC-migration induced by unstimulated or thrombin-activated vascular cells. Together, these data show that endocardial and other vascular cells can induce migration of human MC. This MC-chemotactic signal of the vasculature is associated with expression and release of MGF, augmentable by thrombin, and may play a role in the pathophysiology of (auricular) thrombosis.

Eighteen different permeable membrane supports with and without confluent endothelial cell monolayers were incubated with normal donor derived neutrophils in the upper chambers of a 24 multiwell double chamber system. In order to study transmembrane or transendothelial leukocyte migration leukocytes were stimulated by chemoattractants, or endothelial cells were activated by IL-1. After coincubation the membrane supports building the upper chambers were discarded. Using this technique, leukocytes that had migrated into the lower chamber were exposed to the fluorescent dye calcein AM without additional washing or transfer steps. Absolute cell counts were determined computer assisted using dilution series of calcein AM labeled leukocytes as standards. Serial dilutions of neutrophils exposed to calcein AM showed reproducible linear fluorescence intensity, and relative fluorescence intensity correlated significant with cell counts (r2 = 0.974, p < 0.0001). Out of 18 membrane supports only one was suitable for our assay set up. Best technical and optical performance was achieved with a membrane made of polyethylene terephtalate with a pore size of 3 mm at a pore density of 0.8 x 10(6)/cm2. Stimulation of leukocytes or endothelium by FMLP or IL-1 revealed an increase of transendothelial migration to 7.2 +/- 1.8 x 10(5) PMN and 5.1 +/- 0.7 x 10(5) PMN respectively if compared with medium (0.6 +/- 0.2 x 10(5) PMN). IL-1 induced migration of neutrophils was inhibited by anti IL-1 autoantibodies derived from chronic renal failure patients (IL-1: 100% of PMN migrated, anti IL-1 antibody: 39% of PMN migrated, control antibody: 84% of PMN migrated). In summary, a simple fluorimetric assay was established for the quantification of transmembrane and transendothelial leukocyte migration.