3 – Basics
5th SERVIER FELLOWSHIP. Presentation of the new winner’s project:
Erythrocyte diapedesis during chronic venous insufficiency
C. Rosi / Italy
Chronic venous insufficiency (CVI) causes venular hypertension with erythrocyte diapedesis and cutaneous deposition of hemosiderin leading to lipodermatosclerosis and ulceration. In a preliminary study, the author evaluated skin samples from legs with CVI to assess the mechanism of dermal damage by means of histology, histochemistry, and immunohistochemistry data, and with drug administration of micronized purified flavonoid fraction (MPFF). Skin samples were from patients of CEAP classification C2, C3, C4a, C4b, C6. The erythrocyte diapedesis occurred only during active inflammatory phases of skin dermopathy. In the presence of MPFF, the action of MPFF mitigated the effects of the inflammatory action and deposition of hemosiderin.
4th SERVIER FELLOWSHIP. Presentation of the 2005 winner’s research:
Physiological and histological characteristics of porcine model of superficial varicose veins
G.T. Jones, M. Grant, I.A. Thomson, A.M. Van Rij / New Zealand
This study determined the pathophysiological basis of superficial varicose veins in a novel porcine model, as assessed by intravenous blood pressure, duplex ultrasound, histology, and vein wall homogenate substrate zymography.
Right femoral arteriovenous fistulae were surgically fashioned in adult pigs. Gross superficial varicosities developed after an initial lag period of 1-2 weeks. Varices appeared to have a postural component to their filling and did not seem to be the direct result of venous hypertension per se (non-pulsatile, with a mean pressure of 23 mm Hg).
Venous blood flow velocities were elevated from approximately 5 cm/s in controls to 15-25 cm/s in animals with patent fistulae.
Histopathological changes in porcine vein structure included the development of enlarged tortuous veins, valve degeneration, failure of elastic tissue, and focal medial atrophy with or without overlying intimal thickening. It was concluded that the superficial varicose veins that developed within this porcine model have a pathophysiology that is consistent with that observed in humans.
HMG-CoA reductase inhibitors reduce matrix metallo-proteinase-9 activity in human varicose veins
S. Nomura, K. Yoshimura, N. Morikage, A. Furutani, H. Aoki, M. Matsuzaki, K. Hamano / Japan
Varicose veins are an important public health problem because of their prevalence and morbidity. Because the molecular pathogenesis of varicose veins is still unclear, few pharmacological options to treat varicose veins are available. The effects of MGH-CoA reductase inhibitors (statins) on matrix metalloproteinase MMP-9 were therefore investigated in human varicose veins, because MMP-9 is implicated in disruption of extracellular matrix in varicose veins.
Saphenous vein samples were obtained from 7 varicose vein patients and from 4 patients undergoing artery bypass grafting. Expression levels of MMP-9 protein in the vein walls were analyzed by Western blotting and by immunostaining. Human varicose vein tissue was cultured ex vivo to determine the effect of statins on MMP-9 and urokinase-type plasminogen activator (u-PA), an activator of MMP-9. Secretion levels of MMP-9 and u-PA in the culture media were determined by gelatin zymography and enzyme-linked immunosorbent assay, respectively. The selected activity and mRNA level of MMP-9 were determined by MMP-9 activity assay and quantitative RT-PCR, respectively.
MMP-9 was significantly increased in varicose veins compared with controls mainly in smooth muscle cells at the media, where marked degradation of extracellular matrix was observed. Simvastatin and pravastatin caused striking suppression of MMP-9 activity in ex-vivo culture of varicose vein tissue, while they modestly reduced MMP-9 protein and tended to reduce its mRNA levels. Interestingly, simvastatin significantly suppressed u-PA secretion. Furthermore, while tumor necrosis factor TNF-a, a proinflammatory cytokine, caused a large increase in MMP-9 activity secreted from varicose veins, simvastatin reduced MMP-9 at both the mRNA and protein levels and also u-PA protein level, resulting in the dramatic suppression of MMP-9 activity induced by TNF-a.
Statins suppressed multiple mechanisms of MMP-9 production and activation, resulting in synergistic suppression of MMP-9 activity in varicose veins. Statins may be useful in treating this common disease.
Vascular endothelial growth factor (VEGF) and VEGF-Receptor (VEGF-R) in the pathogenesis of primary and recurrent varicose veins
S. Rewerk, K. Labretsas, M. Winkler, H. Nüllen, C. Duczek, A.J. Meyer, A. Gruber, R. Grobholz, N. Thomas / Germany
VEGF is known to be one of the strongest stimulators for angiogenesis in many different tissues. To initiate this process, the VEGF-R must be present on the endothelial cell surface. Patients were distributed into a control group (n=16), a primary varicose vein group (n=110), and a group with recurrent varicose veins after crossectomy (n=24). Thin-walled veins embedded in scar tissue (neovascularization) were stained immunohistochemically with antibodies against VEGF and its receptor VEGF-R. Higher staining intensity was seen in the recurrence group than in the controls, indicating that VEGF and VEGF-R may play an important role in angiogenesis associated with recurrent varicose veins.