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Objective: Atherosclerosis, a chronic inflammatory disease, arises from metabolic disorders and is driven by inappropriate recruitment and proliferation of monocytes / macrophages and vascular smooth-muscle-cells. The receptor for the urokinase-type plasminogen activator (uPAR, Plaur) regulates the proteolytic activation of plasminogen. It is also a coactivator of integrins and facilitates leukocyte-endothelial interactions and vascular smooth-muscle-cell migration. The role of uPAR in atherogenesis remains elusive. Methods and Results: We generated C57Bl6/J low-density lipoprotein receptor (LDL) and uPAR double knockout (uPAR-/-/LDLR-/-) mice to test the role of uPAR in two distinct atherosclerosis models. In LDLR-/- mice, hepatic overexpression following hydrodynamic transfection of soluble uPAR that competes with endogenous membrane-bound uPAR was performed as an interventional strategy. Aortic root atherosclerotic lesions induced by feeding a high-fat diet were smaller and comprised less macrophages and vascular smooth-muscle-cells in double knockout mice and animals overexpressing soluble uPAR when compared to controls. In contrast, lesion size, lipid-, macrophage-, and vascular smooth muscle cell content of guide-wire-induced intima lesions in the carotid artery were not affected by uPAR deficiency. Adhesion of uPAR-/--macrophages to TNFα-stimulated endothelial cells was decreased in vitro accompanied by reduced VCAM-1 expression on primary endothelial cells. Hepatic overexpression of soluble full-length murine uPAR in LDLR-/- mice led to a reduction of diet-induced atherosclerotic lesion formation and monocyte recruitment into plaques. Ex vivo incubation with soluble uPAR protein also inhibited adhesion of macrophages to TNFα-stimulated endothelial cells in vitro. Conclusion: uPAR-deficiency as well as competitive soluble uPAR reduced diet-promoted but not guide-wire induced atherosclerotic lesions in mice by preventing monocyte recruitment and vascular smooth-muscle-cell infiltration. Soluble uPAR may represent a therapeutic tool for the modulation of hyperlipidemia-associated atherosclerotic lesion formation. [ABSTRACT FROM AUTHOR]

Platelet dysfunction can cause clinically relevant bleeding. Treatment with DDAVP is advocated for this condition. DDAVP increases von Willebrand factor (VWF) on endothelial cells (ECs) and in plasma. VWF could facilitate platelet deposition on subendothelial collagen. VWF also facilitates platelet/EC interactions. Therefore DDAVP could precipitate thromboembolic events. We used a flow chamber model to study in vitro and ex vivo if DDAVP alters recruitment of platelets to EC and collagen. Resting or TRAP-activated platelets and EC were treated individually or simultaneously with 0.4 ng/ml DDAVP. Fluorophor-labeled platelets (106/ml) were resuspended in reconstituted blood and superfused across EC and collagen in an in vitro flow chamber model at arterial shear (320 s−1). Adhesion of platelets to the respective surface was recorded fluorescence microscopically and platelet covered area was assessed. TRAP significantly induced adhesiveness of platelets for collagen and EC. DDAVP pretreatment of platelets did not affect adhesiveness of resting or TRAP-activated platelets for collagen or EC. Adhesiveness of resting but not TRAP-activated platelets was induced on DDAVP-treated EC. DDAVP-conditioned EC supernatant contained vWF and significantly increased platelet deposition on collagen. Platelets from patients with clinically suspected platelet dysfunction undergoing aortic valve replacement exhibited decreased platelet deposition on collagen surfaces. In summary, our data confirm that DDAVP can induce release of platelet adhesion promoting factors from EC, which is most likely vWF. DDAVP has no direct effect on platelets. Blood samples from DDAVP-treated patients do not exhibit significantly augmented platelet deposition on collagen ex vivo. This influence of released promoting factors might cause an increase of undesirable interactions of platelets with EC. [ABSTRACT FROM AUTHOR]

Objectives: We evaluated the role of intracoronary, intrapulmonary and macrophage-mediated delivery of C. pneumoniae (Cp) on coronary lesion formation. Methods: Pigs were allocated to one of three coronary protocols (intracoronary, macrophage or control groups) or to a fourth—a pulmonary group. In the intracoronary group Cp was injected into the wall of the left anterior descending (LAD) and right coronary arteries (RCA) and vehicle into the circumflex (CX). In the macrophage group autologous macrophages preincubated with Cp or not were injected into the LAD and CX wall, respectively. Animals in the control group received vehicle in LAD and CX. In the pulmonary group aerosolised Cp was given intrabronchially, after a single injection of vehicle into the LAD wall. Delivery into the coronary artery wall was performed with a balloon catheter with low-profile injector ports. Results: Seroconversion occurred in the following proportions: 5/6 (intracoronary group), 4/5 (macrophage group), 0/6 (control group), and 1/6 (intrapulmonary group). Significantly higher maximal intimal thickness (MIT) was observed in LADs of intracoronary and pulmonary groups when compared to corresponding CXs. The presence of Cp antigen was associated with higher MIT (r=0.73; P<0.0001). Injection of macrophages into the coronary artery wall did not induce proliferation. Arteries without coronary interventions were morphologically normal. Conclusions: Intracoronary and intrapulmonary but not macrophage-mediated Cp inoculation were associated with moderate intimal proliferation in the absence of a lipid-rich diet. Pre-existing coronary lesions seem a prerequisite for Cp-induced proliferation. [Copyright &y& Elsevier]

Objective: To assess the effect of hypercholesterolemia on neointima formation and vascular remodelling after porcine coronary angioplasty. Methods: Left anterior descending coronary angioplasty was carried out in five control and 16 age-matched hypercholesterolemic miniature pigs. Vascular remodelling was measured by intravascular ultrasound. Neointima size and composition were assessed by quantitative image analysis. Coronary smooth muscle cells (SMC) from control and diet pigs were collected 1 h after angioplasty for in vitro study of the effect of hypercholesterolemic serum on SMC migration and of macrophage-induced matrix degradation on SMC adhesion. Results: Twenty-eight days after angioplasty, lumen increase was 0.08±1.7 mm2 in diet and 2.7±2.7 mm2 (P=0.016) in control pigs. Lumen increase correlated with vascular remodelling (IELpost/IELpre; R2=0.59; P<0.001) and with the circumferential gain relative to the neointima (R2=0.32; P<0.01) but not with neointimal area that was similar in control and diet pigs. Circumferential gain correlated with VSMC deposition at the site of the injury (R2=0.28; P<0.01) that correlated with organized collagen (R2=0.34; P<0.01). The VSMC and collagen content of neointima in diet pigs was lower whereas the macrophage content was higher. Hypercholesterolemic serum and oxidised LDL reduced migration of VSMC from diet pigs. Macrophage-induced degradation of VSMC extracellular matrix reduced VSMC adhesion (P=0.015). Conclusion: Hypercholesterolemia impairs vascular remodelling of balloon-treated coronary arteries. It decreases VSMC and collagen accumulation at the site of injury. Our in vitro data suggest that this decrease can be due to macrophage-induced matrix degradation and reduced VSMC adhesion and to impaired VSMC migration. Oxidised LDL mimics the inhibitory effect of hypercholesterolemic serum. [Copyright &y& Elsevier]

Focuses on impaired myocardial angiogenesis and ischemic cardiomyopathy in mice lacking the vascular endothelial growth factor isoforms VEGF. Generation of VEGF in mice; Impaired cardiac performance; Impaired myocardial angiogenesis.

Abstract: Tissue loss after myocardial ischemia with reperfusion (MI/R) is in part conveyed by neutrophil recruitment to post-ischemic myocardium. Strategies to prevent reperfusion injury would help to limit myocardial damage. The receptor for activated complement factor 5 (C5aR) plays a prominent role in inflammation. We examine the effects of C5aR-deficiency on reperfusion injury after MI/R. C5aR−/−-mice and their C57BL/6- (WT) littermates underwent transient myocardial ischemia followed by different time points of reperfusion. Infarct size and leukocyte infiltration were determined. Expression of C5aR, inflammatory cytokines and adhesion molecules were analyzed by real-time RT-PCR. Leukocyte-endothelial interactions were assessed by low-shear adhesion- and transmigration-assays in vitro. Myocardial C5aR mRNA expression was 2.8-fold increased by ischemia. Infarct size per area-at-risk and leukocyte recruitment into infarctions were reduced in C5aR−/−-compared to WT-mice as well as in WT mice treated with the C5aR-antagonist JPE1375. IL-6, IL-1β, ICAM-1 and VCAM-1 expression were not different, while TNFα expression was reduced in C5aR−/−-mice after MI/R. In vitro, C5aR on leukocytes is required for effective transendothelial migration but not adhesion. Expression of MMP9 and JAM-A, molecules that are involved in leukocyte transmigration, were reduced in C5aR−/− mice in vivo. Genetic C5aR deficiency blunts the inflammatory response in murine MI/R resulting in reduced inflammatory cell recruitment, which is due to a C5aR-dependent effect on leukocyte transmigration across inflamed endothelium into the ischemic myocardium. This effect could be related to MMP9- and JAM-A expression in response to ischemia and reperfusion. [Copyright &y& Elsevier]

Aims Myocardial infarction (MI) results in acute impairment of left ventricular (LV) function through the initial development of cardiomyocyte death and subsequent progression of LV remodelling. The expression of syndecan-4 (Sdc4), a transmembrane proteoglycan, is up-regulated after MI, but its function in the heart remains unknown. Here, we characterize the effects of Sdc4 deficiency in murine myocardial ischaemia and permanent infarction. Methods and results Targeted deletion of Sdc4 (Sdc4–/–) leads to increased myocardial damage after ischaemic–reperfusion injury due to enhanced cardiomyocyte apoptosis associated with reduced activation of extracellular signal-regulated kinase in cardiomyocytes in vitro and in vivo. After ischaemic–reperfusion injury and permanent infarction, we observed an increase in cardiomyocyte area, nuclear translocation of nuclear factor of activated T cells (NFAT), and transcription of the NFAT target rcan1.4 in wild-type mice. NFAT pathway activation was enhanced in Sdc4–/– mice. In line with the in vivo data, NFAT activation and hypertrophy occurs in isolated cardiomyocytes with reduced Sdc4 expression during phenylephrine stimulation in vitro. Despite the initially increased myocardial damage, echocardiography revealed improved LV geometry and function in Sdc4–/– mice 7 days after MI. Conclusion Interception of the Sdc4 pathway enhances infarct expansion and hypertrophic remodelling during early infarct healing in ischaemic–reperfusion injury and permanent infarction mouse models and exerts net beneficial effects on LV function. [ABSTRACT FROM PUBLISHER]

Aggrecan cleavage by a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 5 (ADAMTS-5) is crucial for the breakdown of cartilage matrix during osteoarthritis, a degenerative joint disease that leads to the progressive destruction of articular structures. The mechanisms of ADAMTS-5 activation and their links to the pathogenesis of osteoarthritis remain poorly understood, but syndecans have been shown to be involved in the activation of ADAMTS-4 (ref. 3). Here we show that syndecan-4 is specifically induced in type X collagen–producing chondrocytes both in human osteoarthritis and in murine models of the disease. The loss of syndecan-4 in genetically modified mice and intra-articular injections of syndecan-4–specific antibodies into wild-type mice protect from proteoglycan loss and thereby prevent osteoarthritic cartilage damage in a surgically induced model of osteoarthritis. The occurrence of less severe osteoarthritis-like cartilage destruction in both syndecan-4–deficient mice and syndecan-4–specific antibody–treated wild-type mice results from a marked decrease in ADAMTS-5 activity. Syndecan-4 controls the activation of ADAMTS-5 through direct interaction with the protease and through regulating mitogen-activated protein kinase (MAPK)-dependent synthesis of matrix metalloproteinase-3 (MMP-3). Our data suggest that strategies aimed at the inhibition of syndecan-4 will be of great value for the treatment of cartilage damage in osteoarthritis. [ABSTRACT FROM AUTHOR]

Aims: The progression of human heart failure is associated with increased protein phosphatase 1 (PP1) activity, which leads to a higher dephosphorylation of cardiac regulatory proteins such as phospholamban. In this study, we tested the hypothesis whether the inhibitor-2 (I-2) of PP1 can mediate cardiac protection by inhibition of PP1 activity. [ABSTRACT FROM PUBLISHER]

Focuses on impaired myocardial angiogenesis and ischemic cardiomyopathy in mice lacking the vascular endothelial growth factor isoforms VEGF. Generation of VEGF in mice; Impaired cardiac performance; Impaired myocardial angiogenesis.