Prostanoid production in varicose veins: evidence for decreased prostacyclin with increased thromboxane A2 and prostaglandin E2 formation

Anti-Inflammatory and Anti-Vascular Leakage Effects by Combination of Centella asiatica and Vitis vinifera L. Leaf Extracts

Venous insufficiency results from several factors responsible for the progression of inflammation and oxidative damage of veins. Recently, natural extracts have been proposed for the treatment of venous insufficiency, but their efficacies have not been fully elucidated. In the present study, we evaluate the combinatorial effects on anti-inflammatory and anti-vascular leakage potential of mixed compositions containing different proportions of Centella asiatica extract (CE) and Vitis vinifera L. leaf extract (VVE) using an inflammation model of lipopolysaccharide- (LPS-) stimulated RAW264.7 cells and various vascular permeability models in mice (acetic-acid-induced peritoneal vascular model, mustard-oil-stimulated ear vascular model, and carrageenan-induced paw edema model). Pretreatment of CE and VVE in a 1 : 3 combination dose dependently inhibited the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) and mRNA expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) through downregulation of the nuclear factor-κB (NF-κB) pathway in LPS-stimulated RAW264.7 macrophages. In vascular permeability-related mouse models, pretreatment with the CE-VVE 1 : 3 combination significantly reduced the permeability of peritoneal or ear veins caused by acetic acid and mustard oil, respectively. Furthermore, pretreatment of the CE-VVE 1 : 3 combination ameliorated inflammation and edema of the hind paw caused by carrageenan injection. Thus, the combination of CE and VVE showed significant anti-inflammatory qualities and anti-vascular leakage effects. These findings indicate that an optimal combination of CE and VVE may have a more synergistic effect than that of CE or VVE alone as a putative agent against vascular incompetence.

Transforming growth factor-β1 and inducible nitric oxide synthase signaling were involved in effects of prostaglandin E2 on progression of lower limb varicose veins

OBJECTIVE

The vital pathogenesis of varicose veins includes remodeling of the extracellular matrix and decreased vascular tone. Prostaglandin E₂ (PGE₂), a small molecule substance and inflammatory medium that belongs to the arachidonic acid derivatives, has the capacity to influence the expression of metalloproteinase and the vascular tone of the venous wall. The purpose of the present study was to investigate the role of PGE₂ in the development of varicose veins in lower limbs.

METHODS

The collected venous specimens were analyzed using hematoxylin and eosin, Masson's trichrome, and immunohistochemical staining. Transforming growth factor (TGF)-β1, PGE₂, CD31, and α-smooth muscle actin antibody were used to detect the expression and distribution of these proteins. The effect of PGE₂ on the proliferation, migration, and tube formation capacity of human umbilical vein endothelial cells (HUVECs) was detected in vitro. The effect of TGF-β1 on the expression of PGE₂ and matrix metalloproteinases (MMPs) was assessed using Western blotting. Quantitative reverse transcription polymerase chain reaction was used to evaluate the effect of PGE₂ on the expression of nitric oxide synthase (NOS) and other genes.

RESULTS

The expression of PGE₂ and TGF-β1 in varicose veins was upregulated in the media tunica and intima tunica, and a strong positive correlation was found between PGE₂ and TGF-β1 expression in both varicose veins (95% confidence interval, 0.5207-0.9582; R = 0.848; P = .0005) and normal veins (95% confidence interval, 0.2530-0.8532; R = 0.643; P = .003). PGE₂ promoted the migration and tube formation ability of HUVECs. Moreover, PGE₂ also upregulated the expression of MMP-1 and TGF-β1 in HUVECs and increased the mRNA level of inducible NOS.

CONCLUSIONS

PGE₂ can affect the remodeling of the extracellular matrix and reduce the elasticity of the vascular walls by promoting the synthesis of TGF-β1 and MMP-1. PGE₂ can also reduce the tension of the great saphenous vein by promoting the expression of inducible NOS, thus aggravating the blood stasis.

Oxygen-Derived Free Radicals as Mediators of Varicose Vein Wall Damage

Varicose saphenous vein segments, segments of those veins with thrombophlebitis, and segments of normal veins obtained during operation on 23 patients were studied to define the pattern of pro-oxidative and antioxidative systems in these tissues. In segments of varicose veins (VV) the activity of superoxide dismutase (SOD) was significantly decreased as compared with normal veins: 7.8 ±2.9 vs 13.5 ±4.3 U/mg of protein (P < 0.05), but it was almost unchanged in the segments of W with thrombophlebitis. The activity of glutathione reductase (GSH-R) in all studied segments was similar and amounted to about 12.0 IU.

The content of free sulfhydryl (SH) groups, the concentration of ascorbic acid, and thiobarbituric acid-reactive substances (TBA-RS) in segments of VV were significantly decreased by 40%, 48%, and 47%, respectively (P < 0.05) as compared with segments of normal veins. The values of ascorbic acid and TBA-RS in the segments of W with thrombophlebitis were increased by 13% and 16%, respectively, as compared with segments of normal veins. Decreased activities of SOD and reduced levels of free SH-groups and of ascorbic acid concentration in W may indicate impaired antioxidant mechanisms in this tissue.

Primary Varicose Veins: Altered Transcription of VEGF and its Receptors (KDR, flt-1, Soluble flt-1) with Sapheno-femoral Junction Incompetence

OBJECTIVE

Loss of regulation of vascular endothelial growth factor (VEGF) production and action disturbs vascular homeostasis leading to pathology. Primary varicose veins (VVs) demonstrate aberrant production/release of VEGF. Our aim was to examine transcription of genes for VEGF (VEGF(121)/VEGF(165)) and its receptors (KDR, flt-1, s.flt-1) in VVs, in relation to underlying venous incompetence.

MATERIALS AND METHODS

Samples of varicose (n=83, 18 patients) or normal (n=14, five subjects) great saphenous vein were divided into segments, determined by anatomical position from the sapheno-femoral junction (SFJ). SFJ and segmental incompetence were determined from duplex scans. Gene transcripts were amplified by RT-PCR, analysed by scanning densitometry, and the levels of transcription determined by ratio to control gene GADPH-3 (GAP-3).

RESULTS

VEGF(121)/(165), KDR and flt-1 transcription was elevated in VVs overall (p<0.001), and in VVs with an incompetent SFJ (p<0.001), but not when the SFJ was functional; s.flt-1 was unaltered. Notably, gene transcription was unaffected by segmental position, or incompetence. Position below the SFJ correlated with increased transcription of s.flt-1 when the SFJ was incompetent (p<0.04), and s.flt-1 and VEGF(121) when the segment was incompetent (p<0.03).

CONCLUSIONS

SFJ incompetence is associated with altered transcription of VEGF and its receptors reflecting an aetiological mechanism or later stage of disease development. Altered VEGF(121) and s.flt-1 transcription may be an early event in varicogenesis.

8-Epi-PGF2alpha and 6-oxo-PGF1alpha in human (varicose) veins: influence of age, sex, and risk factors

The isoprostane 8-epi PGF2alpha is a vasoconstrictive, mitogenic, proliferative, and mild proaggregatory agent. We examined 8-epi-PGF2alpha and 6-oxo-PGF1alpha from venous tissue derived from varicose (venous) surgery by means of a specific radioimmunoassay. A total of 336 samples from 82 patients (50 females, 32 males; aged 22-68 years) were examined. Tissue samples were classified according to normal, dilated, and varicose. Of these, 94 samples from 31 patients (20 females, 11 males; aged 29-64 years) with additional risk factors (cigarette smoking, hyperlipidemia, diabetes mellitus) were determined in the same way. Mean absolute values for 6-oxo-PGF1alpha are not significantly higher for dilated segments followed by varicose and intact samples. No significant age and sex differences can be monitored. Presence of risk factors, however, results in a significantly diminished 6-oxo-PGF1alpha, irrespective of morphology. 8-Epi-PGF2alpha again showed no age and sex dependence, its presence in varicose segments, however, was significantly (p<0.01) decreased. Risk factors resulted in a significantly increased 8-epi-PGF2alpha. These data indicate that the influence of risk factors on vasomodulatory (iso-)eicosanoids of human veins is more pronounced than the actual morphologic stage. Lower 8-epi-PGF2alpha in varicose veins may shift the venous tone toward vasodilatation and contribute to development and progression of varicosis.

Pathogenesis of varicose veins

BACKGROUND

varicose veins are present in up to 40% of the population. They may be associated with considerable morbidity. Around 70% of patients with chronic venous insufficiency have evidence of superficial venous incompetence on duplex imaging.

METHODS

in this publication we review the evidence available regarding the pathogenesis of varicose veins.

RESULTS

a number of theories have been suggested. The present data suggests that abnormalities in the venous endothelium and smooth muscle cells result in vein wall dilatation with secondary valvular incompetence. However, there is also evidence to support acquired venous valve failure. Congenital venous valve abnormalities have not been well studied.

CONCLUSION

further work is required on this relatively neglected topic. The use of improved imaging such as high-resolution ultrasound is likely to significantly improve our understanding of venous valve function and pathology.

Imbalance between the endothelial cell-derived contracting factors prostacyclin and angiotensin II and nitric oxide/cyclic GMP in human primary varicosis

1. The role of the endothelium in the vasomotor control of human veins in the lower extremity is little understood. We tested the hypothesis that the production of relaxing and contracting factors is altered in endothelial cells from varicose saphenous veins which may predispose to the decreased vessel tone observed in primary varicosis. 2. We determined the intracellular accumulation of guanosine 3':5'-cyclic monophosphate cyclic GMP; a measure of nitric oxide production and the release of endothelin and prostacyclin (measured as its stable metabolite 6-keto-prostaglandin F1alpha) from cultured cells derived from the long saphenous veins of patients with primary varicosis (Varicose saphena group, n = 27) or from patients undergoing coronary artery bypass surgery (Healthy saphena group, n = 22). In addition, levels of endothelin, angiotensin II, bradykinin, cyclic GMP and cyclic AMP in plasma from patients with primary varicosis and healthy volunteers (n = 8-11 in each group) were determined. 3. Although basal cyclic GMP levels were similar, more cyclic GMP accumulated in response to histamine (1-100 micromol l[-1]) in cells from varicose saphenous veins (0.75 +/- 0.1 pmol per well) than in cells from veins without varicosis (0.27 +/- 0.05 pmol per well). Furthermore, the relaxant potency of nitroprusside (1 nmol l(-1) - 300 micromol l[-1]) in vitro was higher for varicose veins (mean EC50 = 5.9 micromol l(-1); n = 8) than healthy veins (mean EC50 = 20.0 micromol l(-1); n = 7). 4. The production of prostacyclin was significantly less in cells from varicose than healthy saphenous veins (66 +/- 8.7 and 121 +/- 20.1 nmol g(-1) protein), but the production of endothelin was similar in both groups. Prostacyclin (3 nmol l(-1) 30 micromol l[-1]) consistently contracted rings of varicose saphenous vein in vitro with a mean EC50 value of 10-20 micromol l(-1) (n = 7); the maximum tension generated was approximately 50% of that of a completely depolarizing solution of K+ (120 mmol l[-1]). 5. In plasma from patients with varicose veins, levels of cyclic GMP were higher than in healthy controls (9.2 +/- 0.03 and 7.2 +/- 0.02 nmol l[-1]), levels of angiotensin II were lower (81 +/- 11.5 and 147 +/- 21.7 pmol l[-1]), and levels of endothelin, cyclic AMP, and bradykinin were not different. 6. It is concluded that endothelial cells from diseased saphenous veins secrete less constrictor mediators than cells from healthy veins and that in diseased veins the nitric oxide/cyclic GMP system is up-regulated which may shift the balance of vasoactive factors towards vasodilatation and contribute to the development of primary varicosis.

Plasma endothelin-1 release in normal and varicose saphenous veins

The aim of the study was to investigate the release of endothelin-1 (ET-1) in normal and varicose saphenous veins at baseline and after venous stasis test. Ten patients (eight women and two men, mean age 43 +/- 4) with primarily varicose great saphenous veins and ten controls (eight women and two men, mean age 42 +/- 6) were recruited. After 30 minutes of resting in supine position, venous occlusion in a leg was performed with a sphygmomanometer provided to keep the pressure in the cuff intermediate between systolic and diastolic blood pressure for 10 minutes. Blood samples were taken from the great saphenous vein just above the medial malleolus at baseline and 10 minutes after venous stasis was begun. Plasma ET-1 was determined by a radioimmunoassay system. Results are expressed as mean +/- SD. Plasma ET-1 concentration was higher in varicose than in normal saphenous veins (4 +/- 0.1 pmol/L vs 2.6 +/- 0.1 pmol/L, P < 0.001), and it significantly increased (P < 0.001) in both groups after venous stasis when compared with baseline (6.8 +/- 0.9 pmol/L and 3.6 +/- 0.1 pmol/L in varicose and normal saphenous veins, respectively). Absolute increase in plasma ET-1 was significantly greater in varicose than in normal saphenous veins (2.8 +/- 0.9 pmol/L vs 1.0 +/- 0.2 pmol/L, P < 0.01). In conclusion, increased local ET-1 release in varicose saphenous veins could be a marker for venous endothelial activation/damage and/or contribute to promote the morphologic alterations of the varicose vein wall by stimulating smooth muscle cell proliferation. On the other hand, increased ET-1 release could contribute to counterbalancing the varicose venous relaxation and to increasing preload in varicose patients via ET-1-induced venoconstriction.

Characterization of endothelin receptors in human varicose veins

PURPOSE

Experiments were designed to characterize endothelin receptors in human varicose veins. Three groups of veins were studied: (1) varicose vein (VV) tributaries of the greater saphenous vein from patients who were undergoing vein stripping for primary varicosity; (2) greater saphenous veins (SVs) from the same patients; and (3) greater saphenous veins from patients without varicosity who were undergoing arterial reconstruction (control).

METHODS

Veins were either cut into rings and suspended in organ chambers for measurement of isometric force, prepared for receptor binding of membrane proteins, or were prepared for measurement of preproendothelin mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Endothelin-1 (10(-11) to 10(-7) mol/L) produced similar concentration-dependent contractions in rings with or without endothelium. Maximal tensions were significantly greater in control veins compared with either SVs or VVs. Sarafotoxin S6c (10(-11) to 3 x 10(-7) mol/L), which is selective for the endothelin-B receptor, also produced concentration-dependent increases in tension in all veins. Sarafotoxin S6c responses in VVs were shifted significantly rightward compared with either SVs or control. Maximal tensions to sarafotoxin S6c also were significantly greater in control veins compared with either SVs or VVs. In receptor binding studies, the number of binding sites as defined by competitive inhibition of 125I-endothelin-1 by endothelin-1 was less in VVs than control veins. Competitive inhibition of 125I-endothelin-1 with endothelin-3 (both A and B receptors) or sarafotoxin S6c (B receptors only) suggests that the difference in receptor number between varicose and nonvaricose veins is attributable to differences in the endothelin-B receptor subtype. Binding affinities were not significantly different for either of the receptor subtypes in all veins studied. Preproendothelin mRNA as quantitated by RT-PCR tended to be higher in VVs compared with either SVs or control veins.

CONCLUSIONS

Decreased contractions to endothelin-1 in both varicose and saphenous veins of patients with primary varicosity may be associated with a decrease in the number of receptors. These receptors may be downregulated in response to increased production of endothelin-1, which is regulated at the transcriptional level.

Prostacyclin release from the human saphenous vein in diabetics in lower than in nondiabetics

The balance between prostacyclin and thromboxane has been suggested to be of great importance for the maintenance of patency in veins. In order to investigate prostacyclin and thromboxane release, segments from the human saphenous veins were investigated in 53 patients. Twenty-seven patients (10 males, 17 females) underwent surgery for varicose veins. Twenty-six patients (14 nondiabetics, 12 diabetics) underwent surgery for lower limb ischemia (rest pain or gangrene) with use of the saphenous vein as arterial conduit. Vein segments were gently excised and perfused ex vivo for five 15 minute periods, with a balanced salt solution and determination of the stable degradation products 6-keto-PGF1 alpha and TxB2. Saphenous veins from patients with varicose veins had an initial prostacyclin release of 61 +/- 13 pg/mm2/15 min declining to 4 +/- 1 pg/mm2/15 min after 60 min (p < 0.001) and increasing after addition to arachidonic acid to 37 +/- 7 pg/mm2/15 min (p < 0.001). Segments from nondiabetic patients with lower limb ischemia did not differ from those of varicectomy patients, but diabetic segments had a significantly lower prostacyclin release than both these groups, 34 +/- 11 pg/mm2/15 min, 1 +/- 1 pg/mm2/15 min, and 7 +/- 5 pg/mm2/15 min, respectively (p < 0.05). The addition of arachidonic acid failed to increase the prostacyclin release in diabetics. Three patients from each group were studied regarding thromboxane release and there was almost no detectable thromboxane in any group. These findings suggest that diabetics have a lowered prostacyclin release from the saphenous vein and that the deficiency is at the cyclo-oxygenase level.(ABSTRACT TRUNCATED AT 250 WORDS)