BACKGROUND\nRecently, we have shown that intraplaque mast cell numbers are associated with atherosclerotic plaque vulnerability and with future cardiovascular events, which renders inhibition of... Show moreBACKGROUND\nRecently, we have shown that intraplaque mast cell numbers are associated with atherosclerotic plaque vulnerability and with future cardiovascular events, which renders inhibition of mast cell activation of interest for future therapeutic interventions. However, the endogenous triggers that activate mast cells during the progression and destabilization of atherosclerotic lesions remain unidentified. Mast cells can be activated by immunoglobulins and in the present study, we aimed to establish whether specific immunoglobulins in plasma of patients scheduled for carotid endarterectomy were related to (activated) intraplaque mast cell numbers and plasma tryptase levels. In addition, the levels were related to other vulnerable plaque characteristics and baseline clinical data.\nMETHODS AND RESULTS\nOxLDL-IgG, total IgG and total IgE levels were measured in 135 patients who underwent carotid endarterectomy. No associations were observed between the tested plasma immunoglobulin levels and total mast cell numbers in atherosclerotic plaques. Furthermore, no associations were found between IgG levels and the following plaque characteristics: lipid core size, degree of calcification, number of macrophages or smooth muscle cells, amount of collagen and number of microvessels. Interestingly, statin use was negatively associated with plasma IgE and oxLDL-IgG levels.\nCONCLUSIONS\nIn patients suffering from carotid artery disease, total IgE, total IgG and oxLDL-IgG levels do not associate with plaque mast cell numbers or other vulnerable plaque histopathological characteristics. This study thus does not provide evidence that the immunoglobulins tested in our cohort play a role in intraplaque mast cell activation or grade of atherosclerosis. Show less
Borne, P. van den; Laan, S.W. van der; Bovens, S.M.; Koole, D.; Kowala, M.C.; Michael, L.F.; ... ; Pasterkamp, G. 2014
Objective: Atherosclerosis is an inflammatory disease, modulated by plaque stabilizing and de-stabilizing cell populations such as infiltrating monocytes and vascular smooth muscle cells (vSMCs).... Show moreObjective: Atherosclerosis is an inflammatory disease, modulated by plaque stabilizing and de-stabilizing cell populations such as infiltrating monocytes and vascular smooth muscle cells (vSMCs). Transcription factors regulating proliferation and differentiation of atherosclerosis relevant cell types are of interest in this context. The forkhead box transcription factor FoxP1 modulates monocyte differentiation. We studied FoxP1 expression in atherosclerotic tissue, correlated FoxP1 expression with plaque characteristics and identified associations between FoxP1 and plaque proteins. Methods: 116 Atherosclerotic plaques from carotid endarterectomy samples were histologically classified (fibrous, fibroatheromatous, atheromatous) and subjected to semi-quantitative protein analysis. Macrophage, SMC content and intraplaque thrombus amount were determined histologically. FoxP1 expression was investigated by western blotting and immunohistochemistry. In addition FoxP1 was overexpressed in vitro to identify causal relations between FoxP1 and plaque proteins. Results: FoxP1 expression was observed in SMCs, macrophages, endothelial cells and T-cells within the plaque. High SMC and collagen content correlated with increased FoxP1 isoform (72 kD and 95 kD) levels. 72 kD FoxP1 expression was lower in plaques containing intraplaque thrombus. FoxP1 correlated with active intraplaque TGF beta signaling. In vitro stimulation of SMCs with TGF beta resulted in increased FoxP1 levels. 72 kD FoxP1 correlated with expression of pro-fibrotic EGR-1 and increased Col1A1 expression. Conclusion: FoxP1 is expressed by different cell types in atherosclerotic lesions and associated with more stable plaque characteristics and intraplaque TGF beta signaling. FoxP1 expression in vitro is induced by TGF beta, resulting in increased collagen and EGR-1 expression, providing a mechanism for the observed association with a more stable plaque phenotype. (C) 2011 Elsevier Ireland Ltd. All rights reserved. Show less
Aims Neutrophil gelatinase-associated lipocalin (NGAL) is an effector molecule of the innate immune system. One of its actions is the prolongation of matrix metalloproteinase-9 (MMP-9) activity by... Show moreAims Neutrophil gelatinase-associated lipocalin (NGAL) is an effector molecule of the innate immune system. One of its actions is the prolongation of matrix metalloproteinase-9 (MMP-9) activity by the formation of a degradation-resistant NGAL/MMP-9 complex. We studied NGAL in human atherosclerotic lesions and we examined whether NGAL could act as a target for molecular imaging of atherosclerotic plaques. Methods and results Increased levels of NGAL and the NGAL/MMP-9 complex were associated with high lipid content, high number of macrophages, high interleukin-6 (IL-6) and IL-8 levels, and low smooth muscle cell content in human atherosclerotic lesions obtained during carotid endarterectomy (n = 122). Moreover, plaque levels of NGAL tended to be higher when intra-plaque haemorrhage (IPH) or luminal thrombus was present (n 77) than without the presence of IPH or thrombus (n 30). MMP-9 and -8 activities were strongly related to NGAL levels. The enhancement on magnetic resonance (MR) images of the abdominal aorta of ApoE(-/-)/eNOS(-/-) mice was observed at 72 h after injection of NGAL/24p3-targeted micelles. The specificity of these results was validated by histology, and co-localization of micelles, macrophages, and NGAL/24p3 was observed. Conclusion NGAL is highly expressed in atheromatous human plaques and associated with increased MMP-9 activity. NGAL can be detected in murine atherosclerotic arteries using targeted high-resolution MR imaging. Therefore, we conclude that NGAL might serve as a novel imaging target for the detection of high-risk plaques. Show less
P>Background Hyaluronic acid is expressed in atherosclerotic lesions, but its exact role in atherosclerotic disease remains unknown. As degradation of hyaluronic acid by hyaluronidase into low... Show moreP>Background Hyaluronic acid is expressed in atherosclerotic lesions, but its exact role in atherosclerotic disease remains unknown. As degradation of hyaluronic acid by hyaluronidase into low molecular weight hyaluronic acid (LMW-HA) is associated with inflammation and Matrix Metalloproteinase (MMP)-9 activity, we hypothesized that hyaluronic acid metabolism is increased in plaques with unstable characteristics like large lipid core, high number of macrophages, MMP-9 activity, low collagen and smooth muscle cell content. Materials and methods Protein was isolated from 68 carotid artery specimens. The adjacent plaque segment was characterized for the histological parameters: lipid core, macrophage, collagen, smooth muscle cell (SMC) content and the amount of intra-plaque thrombus. Hyaluronidase activity, total hyaluronic acid and LMW-HA expression, the standard hayaluronic acid receptor CD44s and the VEGF-A binding isoform CD44v3, MMP-9 activity and the plaque instability associated growth factor Vascular Endothial Growth Factor (VEGF)-A were analysed and correlated with histological characteristics. Results Hyaluronidase activity, LMW-HA and CD44 expression (CD44s, CD44v3) levels were increased in atheromatous plaques compared with fibrous plaques. Total hyaluronic acid did not correlate with plaque instability. MMP-9 activity correlated with CD44s, hyaluronidase and LMW-HA expression. CD44v3 correlated with the angiogenic factor VEGF-A. In vitro stimulation of macrophages with LMW-HA increased MMP-9 activity. Conclusions We show for the first time that increased hyaluronic acid metabolism and elevated CD44 levels are associated with plaque destabilization potentially by increased MMP-9 activity and stimulation of angiogenesis. Show less
