Absence of inflammatory conditions in human varicose saphenous veins.

INTRODUCTION: Varicose veins affect one-third of the adult population in western countries, but their pathogenesis is incompletely characterized. One of the most controversial issues is the role of inflammation. It is well known that inflammation involves an increased expression/activity of inflammatory mediators. OBJECTIVE: The aim of this study was to investigate the presence or absence of mediators of inflammation in varicose as compared to healthy veins. METHODS AND RESULTS: Using immunohistofluorescence on varicose and healthy veins, we investigated the presence of inflammatory cells. They were not detectable. Venous wall C-reactive protein (CRP), fibrinogen (EIA) and pentraxin-3 (Western blot) content were measured. CRP was significantly lower in varicose veins, but no difference was found for fibrinogen or pentraxin-3 between varicose and healthy veins. No difference was observed for enzymes involved in inflammation and responsible for arachidonic acid metabolism such as the acute phase reactant secreted phospholipase A2-IIA and cyclooxygenase-2, as determined in varicose and healthy veins by Western blot and real-time qRT-PCR. CONCLUSIONS: Our experiments demonstrate no increase in the presence of mediators of inflammation in varicose as compared to healthy veins, suggesting that inflammation may not be an important contributor to the pathogenesis of varicose veins.

Early atheroma-derived agonists of peroxisome proliferator-activated receptor-γ trigger intramedial angiogenesis in a smooth muscle cell-dependent manner.

RATIONALE: Neovascularization favors intraplaque hemorrhage and plaque rupture. Development of therapeutic strategies against atheromatous angiogenesis requires elucidation of its initiating factors. OBJECTIVE: We investigated the contribution of smooth muscle cells (SMCs) and atheroma-derived lipids to the initiation of atheroma-associated neoangiogenesis. METHODS AND RESULTS: Forty human aortic segments, each harvested from a different donor, were classified as healthy or as bearing early atheromatous lesions, including fatty streaks and fibrolipidic atheroma, according to their histological features. Immunostaining for blood vessels and vascular endothelial growth factor-A (VEGF-A), as well as measurement of VEGF-A protein and mRNA levels by ELISA and real-time PCR, revealed that angiogenesis and VEGF-A production were enhanced in the medial layer of atheromatous aortas. The intramedial vessel density and invasiveness and the production of VEGF-A by medial SMCs were indeed increased in atheromatous aortas compared with healthy aortas. Furthermore, intimal layers of atheromatous aortas were enriched in soluble lipid mediators capable of inducing a sustained increase in VEGF-A production by medial SMCs, turning these cells into potent inducers of angiogenesis when incorporated into mouse Matrigel implants. Both effects were inhibited by the peroxisome proliferator-activated receptor-γ inhibitor GW9662 and mimicked by its agonist, rosiglitazone. CONCLUSIONS: We show that VEGF-A production is upregulated in medial SMCs of human atheromatous aortas and that peroxisome proliferator-activated receptor-γ agonists derived from early intimal lesions are likely to contribute to this phenotypic change. Our findings suggest that medial SMCs are central organizers of an angiogenic response initiated by the subendothelial accumulation of atherogenic lipids.

Immaturity of microvessels in haemorrhagic plaques is associated with proteolytic degradation of angiogenic factors.

AIMS: We investigated the causes of microvessel immaturity and destabilization in human atherosclerotic lesions. METHODS AND RESULTS: Human atherosclerotic carotid plaques (n = 24) were classified as non-haemorrhagic (NH) or haemorrhagic (Hem), according to their macroscopic aspect and haemoglobin content. Plaque microvessel density and maturity were quantified by immunohistochemistry. Expression of angiogenic factors was studied by immunohistochemistry, in situ hybridization, and ELISA. Plaque-conditioned media were tested for plasmin and elastase activities and for their ability to degrade angiogenic factors and to induce smooth muscle cell migration. Microvessel density and leucocyte infiltration were increased in Hem compared with NH plaques. Plaque vasculature appeared vulnerable as indicated by the absence of alpha-actin-positive mural cells in most plaque vessels. Despite increased numbers of angiogenic factor-expressing microvessels and leucocytes in Hem plaques, lower levels of vascular endothelial growth factor, placental growth factor, and angiopoietin-1 were found in conditioned media from Hem plaques. However, NH and Hem plaques released similar levels of the vascular destabilizing factor, angiopoietin-2. Addition of recombinant angiogenic factors to plaque extracts showed that all factors but angiopoietin-2 were selectively degraded by plasmin and/or elastase released from Hem plaques. Furthermore, conditioned media from Hem plaques showed a reduced ability to induce smooth muscle cell migration. CONCLUSION: Our results provide evidence that immaturity of plaque vessels is associated with the degradation of angiogenic factors by haemorrhage-conveyed leucocytes and proteases.