Background and aims: Lipids play an important role in atherosclerotic plaque development and are interesting candidate predictive biomarkers. However, the link between circulating lipids,... Show moreBackground and aims: Lipids play an important role in atherosclerotic plaque development and are interesting candidate predictive biomarkers. However, the link between circulating lipids, accumulating lipids in the vessel wall, and plaque destabilization processes in humans remains largely unknown. This study aims to provide new insights into the role of lipids in atherosclerosis using lipidomics and mass spectrometry imaging to investigate lipid signatures in advanced human carotid plaque and plasma samples. Methods: We used lipidomics and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) to investigate lipid signatures of advanced human carotid plaque and plasma obtained from patients who underwent carotid endarterectomy (n = 14 out of 17 whose plaque samples were analyzed by DESI-MSI). Multivariate data analysis and unsupervised clustering were applied to identify lipids that were the most discriminative species between different patterns in plaque and plasma. These patterns were interpreted by quantitative comparison with conventional histology. Results: Lipidomics detected more than 300 lipid species in plasma and plaque, with markedly different relative abundances. DESI-MSI visualized the spatial distribution of 611 lipid-related m/z features in plaques, of which 330 m/z features could be assigned based on exact mass, comparison to the lipidomic data, and high mass resolution MSI. Matching spatial lipid patterns to histological areas of interest revealed several molecular species that were colocalized with pertinent disease processes in plaque including specific sphingomyelin and ceramide species with calcification, phospholipids and free fatty acids with inflammation, and triacylglycerols and phosphatidylinositols with fibrin-rich areas. Conclusions: By comparing lipid species in plaque and plasma, we identified those circulating species that were also prominently present in plaque. Quantitative comparison of lipid spectral patterns with histology revealed the presence of specific lipid species in destabilized plaque areas, corroborating previous in vitro and animal studies. Show less
Moerman, A.M.; Visscher, M.; Slijkhuis, N.; Gaalen, K. van; Heijs, B.; Klein, T.; ... ; Soest, G. van 2021
Carotid atherosclerosis is a risk factor for ischemic stroke, one of the main causes of mortality and disability worldwide. The disease is characterized by plaques, heterogeneous deposits of lipids... Show moreCarotid atherosclerosis is a risk factor for ischemic stroke, one of the main causes of mortality and disability worldwide. The disease is characterized by plaques, heterogeneous deposits of lipids, and necrotic debris in the vascular wall, which grow gradually and may remain asymptomatic for decades. However, at some point a plaque can evolve to a high-risk plaque phenotype, which may trigger a cerebrovascular event. Lipids play a key role in the development and progression of atherosclerosis, but the nature of their involvement is not fully understood. Using matrix-assisted laser desorption/ionization mass spectrometry imaging, we visualized the distribution of approximately 200 different lipid signals, originating of >90 uniquely assigned species, in 106 tissue sections of 12 human carotid atherosclerotic plaques. We performed unsupervised classification of the mass spectrometry dataset, as well as a histology-directed multivariate analysis. These data allowed us to extract the spatial lipid patterns associated with morphological plaque features in advanced plaques from a symptomatic population, revealing spatial lipid patterns in atherosclerosis and their relation to histological tissue type. The abundances of sphingomyelin and oxidized cholesteryl ester species were elevated specifically in necrotic intima areas, whereas diacylglycerols and tri-acylglycerols were spatially correlated to areas containing the coagulation protein fibrin. These results demonstrate a clear colocalization between plaque features and specific lipid classes, as well as individual lipid species in high-risk atherosclerotic plaques. Show less
Endothelial cells (EC) translate biomechanical forces into functional and phenotypic responses that play important roles in cardiac development. Specifically, EC in areas of high shear stress, i.e.... Show moreEndothelial cells (EC) translate biomechanical forces into functional and phenotypic responses that play important roles in cardiac development. Specifically, EC in areas of high shear stress, i.e., in the cardiac outflow tract and atrioventricular canal, are characterized by high expression of Kruppel-like factor 2 (Klf2) and by transforming growth factor-beta (Tgf beta)-driven endothelial-to-mesenchymal transition. Extraembryonic venous obstruction (venous clip model) results in congenital heart malformations, and venous clip-induced alterations in shear stress-related gene expression are suggestive for an increase in cardiac shear stress. Here, we study the effects of shear stress on Klf2 expression and Tgf beta-associated signaling in embryonic EC in vivo using the venous clip model and in vitro by subjecting cultured EC to fluid flow. Cellular responses were assessed by analysis of Klf2, Tgf beta ligands, and their downstream signaling targets. Results show that, in embryonic EC, shear stress activates Tgf beta/Alk5 signaling and that induction of Klf2 is an Alk5 dependent process. Developmental Dynamics 240: 1670-1680, 2011. (C) 2011 Wiley-Liss, Inc. Show less
Egorova, A.D.; Heiden, K. van der; Pas, S. van de; Vennemann, P.; Poelma, C.; DeRuiter, M.C.; ... ; Hierck, B.P. 2011
In order to study the role of blood-tissue interaction in the developing chicken embryo heart, detailed information about the haemodynamic forces is needed. In this study, we present the first in... Show moreIn order to study the role of blood-tissue interaction in the developing chicken embryo heart, detailed information about the haemodynamic forces is needed. In this study, we present the first in vivo measurements of the three-dimensional distribution of wall shear stress (WSS) in the outflow tract (OFT) of an embryonic chicken heart. The data are obtained in a two-step process: first, the three-dimensional flow fields are measured during the cardiac cycle using scanning microscopic particle image velocimetry; second, the location of the wall and the WSS are determined by post-processing flow velocity data (finding velocity gradients at locations where the flow approaches zero). The results are a three-dimensional reconstruction of the geometry, with a spatial resolution of 15-20 mu m, and provides detailed information about the WSS in the OFT. The most significant error is the location of the wall, which results in an estimate of the uncertainty in the WSS values of 20 per cent. Show less
Blood-flow-induced shear stress plays an important role in cardiovascular development and disease. How endothelial cells sense shear stress remains to be elucidated. We postulated that the primary... Show moreBlood-flow-induced shear stress plays an important role in cardiovascular development and disease. How endothelial cells sense shear stress remains to be elucidated. We postulated that the primary cilium is a component of the endothelial shear sensor. This luminal cell protrusion contains microtubules and is connected to the microtubular cytoskeleton. We identified cilia on endothelial cells of the embryonic heart in areas of low or oscillatory shear stress. This shear-related distribution is reminiscent of the distribution of atherosclerotic lesions in the adult arterial system, as lesions develop at sites of low or oscillating shear (athero-prone flow). Ciliated endothelial cells are exclusively present at these atherosclerotic predilection sites in adult mice. Athero-prone (oscillatory) but not athero-protective (steady or pulsatile) flow induces ciliation of cultured endothelial cells. Moreover, the endothelial shear response is dependent on the microtubular cytoskeleton and primary cilia sensitise the endothelium for shear. Taken together, these data demonstrate that primary cilia are induced by athero-prone flow and that ciliated cells are more sensitive to shear stress. We conclude that the endothelial biosensor for shear stress is the microtubular cytoskeleton and that the attached primary cilium functions as a signal amplifier in areas subjected to athero-prone flow. Show less
