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Background/aims: The mechanisms that regulate the size-related morphologies of various blood vessels from the aorta to capillary vessels are still poorly understood. In this study, we evaluate the involvement of regulator of calcineurin 1 (RCAN1), a regulatory protein in the calcineurin/NFAT signal transduction pathway, in vascular morphology to gain further insight into these mechanisms., Methods and Results: We first generated 2 types of vasculature in vitro from the same source of human umbilical vein endothelial cells by fibrin gel assay. We found that RCAN1 was significantly upregulated in large vessels with low branching frequencies when compared with small vessels with high branching frequencies. Next, to clarify whether RCAN1 regulates the branching of blood vessels in vivo, we injected RCAN1 mRNA into fertilized Xenopus laevis eggs. Overexpression of RCAN1 decreased the number of branching points that sprouted from intersomitic vessels during X. laevis angiogenesis. In addition, coexpression of calcineurin A, a target of RCAN1, could rescue RCAN1-suppressed vascular branching., Conclusions: These results provide in vivo evidence of RCAN1-regulated vascular branching which may play a role in the patterning of morphologically different vasculature., (Copyright © 2010 S. Karger AG, Basel.)

We previously reported that during total knee arthroplasty in rheumatoid arthritis (RA) patients, the use of tourniquet might promote local release of neutrophil elastase (NE) from neutrophils, which may contribute to the development of pulmonary thromboembolism (PTE) and tissue injury. The aim of this study was to develop PTE by the use of NE in a mouse model of collagen-induced arthritis (CIA) and investigate the relationship between thrombus and endothelial cells as well as the effect of recombinant human soluble thrombomodulin (rhs-TM) in reducing the risk of PTE. Male DBA/1J mice were injected intracutaneously at several sites with an emulsion containing bovine collagen and later a booster shot to produce CIA mice. Subsequently, NE was injected intravenously 2 times a day for 3 days and after a further 4 days, mice were sacrificed. A group of mice received rhs-TM injections prior to NE injections. We divided the mice into four groups of normal, CIA control, CIA + NE, and CIA + rhs-TM + NE mice and evaluated thrombus formation status. All CIA + NE mice developed PTE. In contrast, no thrombosis was found in normal control, CIA control and CIA + rhs-TM + NE mice. Plasma thrombin level, fibrinogen expression and neutrophil count were increased in CIA + NE mice. Double staining for anticoagulant TM and procoagulant von Willebrand factor (vWF) in pulmonary endothelial cells in normal mice showed a TM-dominant expression while in both CIA control and CIA + NE mice a vWF-dominant expression compatible with coagulant status was observed. Injection of rhs-TM into CIA + NE mice resulted in a phenotypic conversion of endothelial cells from vWF-dominant to TM-dominant expression and a reduction in fibrinogen deposition. These findings demonstrate that by repeated use of NE in CIA mice, it is feasible to produce PTE and to study its pathogenesis and that rhs-TM reduces the risk of PTE. We suggest that in surgical operations of upper and lower extremities in RA patients, the use of a tourniquet should be avoided as it may trigger NE release., (Copyright 2008 S. Karger AG, Basel.)

Asthma is a chronic inflammatory disease characterized by airway wall remodeling in which vascular remodeling is thought to be a main contributor. Vascular endothelial growth factor (VEGF) is known as a major regulator of angiogenesis and enhancer of vascular permeability. Here, we define the spatial nature of vascular remodeling and the role of VEGF and its receptors (Flt-1 and Flk-1) in the allergic response in mice (A/J) susceptible to the development of allergen-induced airway hyperresponsiveness using morphometric and quantitative approaches. Increased vascularity, vasodilatation, and endothelial cell proliferation were found in the tracheal and bronchial walls in the early and late phases of asthma. Vascular changes were observed not only in small vessels but also in larger vessels. In contrast to normal control, lung tissue from the asthma model showed dual expression for CD31 and von Willebrand factor in the endothelial cells and alpha-smooth muscle actin and desmin in the mural cells of the vessels, suggesting a phenotypic and functional transformation. The mRNA levels of VEGF isoforms, VEGF(164) and VEGF(188), were significantly increased in the tracheal and lung tissue, respectively. In addition, the mRNA level of VEGF receptor Flk-1 was significantly increased in the trachea. These results establish the existence of vascular remodeling in the airways in a mouse model of allergic asthma and support a key role for the expression of unique VEGF isoform genes as mediators of structural changes., ((c) 2008 S. Karger AG, Basel)

Objective: Protease-activated receptors (PARs) mediate DNA synthesis in endothelial cells when activated by serine proteases. However, despite the existence of heterogeneity among endothelial cells from each tissue, the responses to PAR-1, PAR-2, and PAR-4 activation are poorly defined and compared between endothelial cells from different sites. The aim of this study was to investigate whether PAR-mediated DNA synthesis differed in various endothelial cell types., Methods: We examined the incorporation of BrdU by human pulmonary artery endothelial cells (HPAECs), human aortic endothelial cells (HAECs), and human umbilical vein endothelial cells (HUVECs)., Results: When the endothelial cells were treated with the selective PAR-1-activating peptide, SFLLRN, HAECs showed the highest BrdU incorporation rate (182 +/- 28%). In contrast, treatment with the PAR-2-activating peptide, SLIGKV, resulted in the highest BrdU incorporation rate (173 +/- 37%) in HPAECs, when pretreated with TNF-alpha. The PAR-4-activating peptide, GYPGQV, induced DNA synthesis in HPAECs and HAECs, but not in HUVECs., Conclusion: These findings suggest that each PAR preferentially targets an endothelial cell type, and thus plays a distinct role in diverse physiological or pathological conditions., (Copyright 2004 S. Karger AG, Basel)

Human basophils were purified from normal peripheral blood, using density gradient followed by negative panning selection. We tested the effects of hemopoietic growth factors on the survival of these basophils in vitro. In the absence of exogenous factors, basophils (purity greater than 90%) decreased in number rapidly. At day 7 only 11% of the cells remained alive in cultures; less than 1% of cells survived at day 14. Interleukin (IL)-3 maintained numbers of viable cells; cell viability was 67% at day 7 and 45% at day 14. Granulocyte-macrophage (GM)-colony-stimulating factor (CSF) exhibited slight effect on the survival; 33% of cells remained at day 7. Other growth factors including granulocyte (G)-CSF, macrophage (M)-CSF, and IL-4 had no significant effect on the survival of basophils at all. Morphological and functional characterization of cells maintained by IL-3 revealed that they belonged to the basophil lineage. These observations indicate that normal basophils possess functional receptors for IL-3 and GM-CSF and that both factors modulate immediate- and delayed-type hypersensitivity reactions by prolonging the life span of basophils.