The presence of mast cells in human atherosclerotic plaques has been associated with adverse cardiovascular events. Mast cell activation, through the classical antigen sensitized-IgE binding to... Show moreThe presence of mast cells in human atherosclerotic plaques has been associated with adverse cardiovascular events. Mast cell activation, through the classical antigen sensitized-IgE binding to their characteristic Fcε-receptor, causes the release of their cytoplasmic granules. These granules are filled with neutral proteases such as tryptase, but also with histamine and pro-inflammatory mediators. Mast cells accumulate in high numbers within human atherosclerotic tissue, particularly in the shoulder region of the plaque. These findings are largely based on immunohistochemistry, which does not allow for the extensive characterization of these mast cells and of the local mast cell activation mechanisms. In this study, we thus aimed to develop a new flow-cytometry based methodology in order to analyze mast cells in human atherosclerosis. We enzymatically digested 22 human plaque samples, collected after femoral and carotid endarterectomy surgery, after which we prepared a single cell suspension for flow cytometry. We were able to identify a specific mast cell population expressing both CD117 and the FcεR, and observed that most of the intraplaque mast cells were activated based on their CD63 protein expression. Furthermore, most of the activated mast cells had IgE fragments bound on their surface, while another fraction showed IgE-independent activation. In conclusion, we are able to distinguish a clear mast cell population in human atherosclerotic plaques, and this study establishes a strong relationship between the presence of IgE and the activation of mast cells in advanced atherosclerosis. Our data pave the way for potential therapeutic intervention through targeting IgE-mediated actions in human atherosclerosis. Show less
Cardiovascular diseases are the major cause of morbidity and mortality in western societies. The most common clinical manifestations are stroke and acute myocardial infarction and in both ailments... Show moreCardiovascular diseases are the major cause of morbidity and mortality in western societies. The most common clinical manifestations are stroke and acute myocardial infarction and in both ailments atherosclerosis is the underlying culprit. Atherosclerosis is a lipid-mediated chronic inflammatory disease, which is accompanied by leukocyte infiltration into the vessel wall. The migration of leukocytes from the circulation to the vessel wall is directed by a specific class of proteins, the chemokines. Therefore it is likely that chemokines have a distinctive role in leukocyte homeostasis at specific stages of atherosclerotic disease progression and during ischemia-reperfusion injury. This thesis encompasses of number of human and experimental mouse studies on the role of chemokines in cardiovascular diseases and atherosclerosis, from which several new targets were identified. For instance it is evident that patients with high levels of the chemokine CCL3 are 10 times more likely to develop severe cardiovascular events in the future. In conclusion, the research described in this thesis provided novel candidates that might be of value for the early prediction of high risk patients. Moreover, the identified candidates may also represent valuable targets for modulation of leukocyte homeostasis in the plaque that could improve atherosclerotic plaque progression and stability. Show less
