Angiogenesis and inflammation in carotid atherosclerosis.

Carotid atherosclerosis is a leading cause of cerebrovascular events. The control of cardiovascular risk factors, i.e. tobacco smoking, alcohol abuse, hypertension, dyslipidemia, diabetes and obesity proved to reduce number of fatal and non-fatal strokes but failed to prevent important number of them. Screening for biomarkers in individuals at high risk of symptomatic vascular disease helped to identify some of them. However, as disease is by its nature multifocal, global testing for biomarkers may have limited practical application. New imaging techniques, including direct visualization of artery metabolism, by 18-FDG-PET, has brought new tools to study local atherosclerosis progression and individual plaque metabolic activity. Advances in molecular biology helped to identify inflammatory genes and its strong link to angiogenesis. The later, is thought to play a key role in the transformation to unstable plaque. Studies of the complex role that plays angiogenesis in plaque development will help in future to design effective therapies addressed at the individual cell level. The purpose of the review is to bring new insights into complicated pathophysiology of carotid atherosclerosis.

Overexpression of hypoxia/inflammatory markers in atherosclerotic carotid plaques.

Hypoxia, angiogenesis and inflammation leads to plaque progression and remodelling and may significantly contribute towards plaque rupture and subsequent cerebrovascular events. Our aim was to study, markers of hypoxia and inflammation previously identified by microarray analysis, in atherosclerotic carotid arteries with low to moderate stenosis. We hoped to describe different cellular populations expressing the studied markers. The location of selected inflammatory molecules obtained as vascular transplants from organ donors were analysed by immunohistochemistry with monoclonal and polyclonal antibodies. Paraffin-embedded sections were cut and probed with antibodies recognizing active B and T-lymphocytes (CD30), hypoxia-inducible factor-1alpha, endoglin (CD105), Interleukin-6 and C-reactive protein. We observed a notable overexpression of HIF-1alpha in inflammatory and hypoxic areas of carotid arteries in all types of lesions from type II-V taken from the patients with carotid stenosis less than 50%. This suggests that HIF-1alpha may have a putative role in atherosclerosis progression and angiogenesis. Dynamic changes in the non-occluding plaques may explain some of the clinical events in patients with low to moderate carotid stenosis.

The normal cellular prion protein and its possible role in angiogenesis.

Cellular Prion Protein (PrPc) is a ubiquitous glycoprotein present on the surface of endothelial cells. Resting vascular endothelial cells show minimum expression of PrPc and can constitutively release PrPc. PrPc participates in cell survival, differentiation and angiogenesis. During development, neonatal brain endothelial cells transiently express PrPc. Our group recently reported upregulation of PrPc in microvessels from ischemic brain regions in stroke patients. Ischemia/hypoxia induces PrPc expression through the activation of extracellular signal-regulated kinase (ERK). All these data suggest that PrPc plays an important role in angiogenic responses. In addition, PrPc participates in cellular function in the central nervous system, since PrPc is also highly expressed in neurons. PrPc binds copper, suggesting a role in copper metabolism. PrPc also protects cells against oxidative stress and it seems to be involved in neuroprotection. Several studies have demonstrated that PrPc prevents cells from apoptosis and subsequent tissue damage. Moreover, PrPc plays an important role in the immune response. Here, we review the multiple functions of PrPc with a special attention to its recently reported role in angiogenesis.