The genetic disorder Down syndrome is associated with a decreased susceptibility for atherosclerotic cardiovascular disease. Hematological and immune abnormalities occur frequently in Down syndrome... Show moreThe genetic disorder Down syndrome is associated with a decreased susceptibility for atherosclerotic cardiovascular disease. Hematological and immune abnormalities occur frequently in Down syndrome patients. We evaluated, in a preclinical setting, the impact of a Down syndrome-like hematological/immune phenotype on atherosclerosis susceptibility. Hereto, hypercholesterolemic low-density lipoprotein receptor knockout mice were transplanted with bone marrow from either a trisomic Ts65Dn mouse or euploid wild-type control and subsequently fed a Western-type diet to induce the development of atherosclerotic lesions. T and B cell concentrations were markedly reduced in blood of Ts65Dn bone marrow recipients (p < 0.001). Expression levels of the pro-atherogenic scavenger receptor CD36 were respectively 37% and 59% lower (p < 0.001) in trisomic monocytes and macrophages. However, these combined effects did not translate into an altered atherosclerosis susceptibility. Notably, blood platelet numbers were elevated in Ts65Dn bone marrow recipients (+57%; p < 0.001), which was paralleled by higher platelet GPVI protein expression (+35%; p < 0.001) and an enhanced collagen-induced platelet activation (p < 0.001). In conclusion, we have shown that providing mice with a Down syndrome-like hematological profile does not change the susceptibility to atherosclerosis. Furthermore, our studies have uncovered a novel effect of the trisomy on platelet functionality that may be relevant in human clinical settings. Show less
Background and aims: Neuroimmune guidance cues have been shown to play a role in atherosclerosis, but their exact role in human pathophysiology is largely unknown. In the current study, we... Show moreBackground and aims: Neuroimmune guidance cues have been shown to play a role in atherosclerosis, but their exact role in human pathophysiology is largely unknown. In the current study, we investigated the role of a c.1769G > T variant in Netrin-1 in (premature) atherosclerosis.Methods: To determine the effect of the genetic variation, purified Netrin-1, either wild type (wtNetrin-1) or the patient observed variation (mutNetrin-1), was used for migration, adhesion, endothelial barrier function and bindings assays. Expression of adhesion molecules and transcription proteins was analyzed by RT-PCR, Western blot or ELISA. To further delineate how mutNetrin-1 mediates its effect on cell migration, lenti-viral knockdown of UNC5B or DCC was used.Results: Bindings assays revealed a decreased binding capacity of mutNetrin-1 to the receptors UNC5B, DCC and beta 3-integrin and an increased binding capacity to neogenin, heparin and heparan sulfate compared to wtNetrin-1. Exposure of endothelial cells to mutNetrin-1 resulted in enhanced monocyte adhesion and expression of IL-6, CCL2 and ICAM-1 compared to wtNetrin-1. In addition, mutNetrin-1 lacks the inhibitory effect on the NF-kappa B pathway that is observed for wtNetrin-1. Moreover, the presence of mutNetrin-1 diminished migration of macrophages and smooth muscle cells. Importantly, UNC5B or DCC specific knockdown showed that mutNetrin-1 is unable to act through DCC resulting in enhanced inhibition of migration.Conclusions: Our data demonstrates that mutNetrin-1 fails to exert anti-inflammatory effects on endothelial cells and more strongly blocks macrophage migration compared to wtNetrin-1, suggesting that the carriers of this genetic molecular variant may well be at risk for premature atherosclerosis. Show less
Meeuwsen, J.A.L.; Vries, J.J. de; Duijvenvoorde, A. van; Velden, S. van der; Laan, S.W. van der; Koeverden, I.D. van; ... ; Jager, S.C.A. de 2019
future AbstractMouse studies have established distinct monocyte subtypes that participate in the process of atherosclerotic lesion formation. The pro-inflammatory Ly6Chigh monocyte subtype actively... Show morefuture AbstractMouse studies have established distinct monocyte subtypes that participate in the process of atherosclerotic lesion formation. The pro-inflammatory Ly6Chigh monocyte subtype actively contributes to murineplaque progression and destabilization. Also in humans, different peripheral monocyte subtypes have been identified, of which the CD14+CD16− classical monocyte is suggested to display similar pro-atherosclerotic properties as the murine Ly6Chigh subtype. We aimed to investigate if circulating CD14+CD16− classical monocytes associate with characteristics of a vulnerable carotid atherosclerotic plaque and if they associate with the risk of secondary adverse manifestations of atherosclerotic disease.We enrolled 175 carotid endarterectomy patients of the Athero-Express biobank in our study. Just prior to surgical procedure, blood was collected and peripheral blood mononuclear cells were isolated. Characterization of monocyte subsets was performed by flow cytometry. Plaque characteristics were semi-quantitatively scored for the presence of fat, collagen, intraplaque hemorrhage and calcification. Vessel density, smooth muscle cells and macrophages were assessed quantitatively on a continuous scale. All features of a vulnerable plaque phenotype, including low amounts of collagen and smooth muscle cells, and increased fat content, vessel density, intraplaque hemorrhage and plaque macrophages were not significantly associated with differential levels of peripheral classical CD14+CD16− monocytes or other monocyte subsets. Using Cox regression models to evaluate the prognostic value of circulating monocyte subtypes, we found that total counts of peripheral monocytes, as well as CD14+CD16− classical and other monocyte subtypes were not associated with the risk of secondary cardiovascular events during 3 years follow-up.Circulating classical CD14+CD16− monocytes do not associate with specific vulnerable plaque characteristics. In addition, they do not predict secondary adverse manifestations. This suggests that in patients with established carotid artery disease, the circulating monocytes do not reflect plaque characteristics and have no value in identifying patients at risk for future cardiovascular events. Show less
Various studies have shown that leukocyteATP-binding cassette transporter A1 (ABCA1) is an anti-atherogenic factor. It has long been assumed that the increased atherosclerosis susceptibility... Show moreVarious studies have shown that leukocyteATP-binding cassette transporter A1 (ABCA1) is an anti-atherogenic factor. It has long been assumed that the increased atherosclerosis susceptibility observed in leukocyte ABCA1 deficient hyperlipidemic mice was due to an accelerated foam cell formation. However, several studies have suggested that leukocyte ABCA1 may also have a beneficial effect on systemic inflammation. In this study we aim to determine the effect of leukocyte ABCA1 deficiency on atherosclerosis susceptibility in mice that are apolipoprotein A1 (apoA1) deficient.To determine the impact of leukocyte ABCA1 on atherosclerosis outcome, lethally irradiated low-density lipoprotein receptorknock-out (sKO) mice or LDLr/apoA1 double KO (dKO) mice were reconstituted with either ABCA1 KO or wild-type bone marrow. All four groups of chimeric mice were fed a Western-type diet for 6 weeks to induce atherosclerotic lesion development.Leukocyte ABCA1 deficiency in dKO mice resulted in 50-70% larger lesions in the aortic root than those observed in both sKO mice transplanted with ABCA1 KO bone marrow and dKO mice transplanted with wild-type bone marrow. Furthermore, total leukocyte numbers in blood were generally higher in mice lacking apoA1 as compared to those containing apoA1-carrying HDL particles. Two way ANOVA on the different white blood cell sub-populations suggested that the apoA1 deficiency-associated increase in total leukocyte counts was driven by an increase in the number of lymphocytes (P<0.001) and, to a minor extent, monocytes (P<0.01).This study shows that reduced systemic inflammation and increased reverse cholesterol transport together drive macrophage ABCA1-mediated protection against atherosclerosis. Show less
