Local plaque characteristics and circulating cells in atherosclerosis. The Athero-Express biobank

This thesis consists of 3 parts. In the first part we investigated the association of local plaque characteristics with clinical presentation by using histological assessments: In chapter 2 we were able to combine data from the Oxford plaque study and the Athero- Express biobank, two of the largest biobanks in the world, and investigated if diabetes, an important risk factor for atherosclerosis, is related with different carotid plaque morphologies. In addition, we determined if cardiovascular outcome was different between patients with or without diabetes. In chapter 3 we assessed different subsets of macrophages and related its presence with vulnerable plaque characteristics. In chapter 4 we associated the presence of matrix-metallo-proteinase-12 (MMP12) positive macrophages with cardiovascular outcome following CEA. The second part of this thesis describes our studies on plaque characteristics throughout the superficial femoral artery (SFA). Chapter 5 describes how intimal cores, derived by remote endarterectomy, enabled us to investigate the histological consequences of previous performed endovascular procedures. Chapter 6 describes how intimal cores enabled us to investigate patterns of mural thrombus formation throughout the SFA. In the third and last part we make a transition towards the blood and demonstrate the results of our Circulating Cells study. Chapter 7 provides a review in which we describe the opportunities and pitfalls in biobanking. Chapter 8 reports Toll like receptor response in relation to obesity. In chapter 9 we describe the potential of cell membrane bounded CD14 as a cardiovascular biomarker in patients with cerebrovascular and coronary artery disease. Chapter 10 demonstrates the association between monocyte activation status and atherosclerotic plaque macrophage content. In chapter 11 we report the results of a study where we related Toll like receptor response with cardiovascular outcome and in chapter 12 we determined the entire proteome of 40 carotid plaques and used unsupervised cluster analysis to group carotid plaques according to their corresponding protein expression profiles

Toll-like receptor 2 and 4 stimulation elicits an enhanced inflammatory response in human obese patients with atherosclerosis.

The innate immune response elicited by activation of TLRs (Toll-like receptors) plays an important role in the pathogenesis of atherosclerosis. We hypothesized that cardiovascular risk factors are associated with the activation status of the innate immune system. We therefore assessed the responsiveness of TLRs on circulating cells in two groups of patients with established atherosclerosis and related this to the presence of cardiovascular risk factors. TNF (tumour necrosis factor)-α release induced by TLR2 and TLR4 activation was measured in patients with established coronary [PCI (percutaneous coronary intervention) study, n=78] or carotid artery disease [CEA (carotid endarterectomy) study, n=104], by stimulating whole blood samples with lipopolysaccharide (TLR4 ligand) and Pam3CSK4 [tripalmitoylcysteinylseryl-(lysyl)4; TLR2 ligand]. As an early activation marker, CD11b expression was measured by flow cytometry on CD14+ cells. Obesity was the ‘only’ risk factor that correlated with the TLR response. In both studies, obese patients had significantly higher TNF-α levels after stimulation of TLR2 compared with non-obese patients [16.9 (7.7–49.4) compared with 7.5 (1.5–19.2) pg/ml (P=0.008) in coronary artery disease and 14.6 (8.1–28.4) compared with 9.5 (6.1–15.7) pg/ml (P=0.015) in carotid artery disease; values are medians (interquartile range)]. Similar results were obtained following TLR4 stimulation. The enhanced inflammatory state in obese patients was also confirmed by a significant increased expression of the activation marker CD11b on circulating monocytes. In conclusion, obesity is associated with an enhanced TLR response in patients suffering from established atherosclerotic disease.</jats:p