Matrix metalloproteinase-9 and urokinase-type plasminogen activator in varicose veins

Intense remodeling of extracellular matrix within the varicose vein: the role of gelatinases and vascular endothelial growth factor

BACKGROUND

Increased blood pressure in the varicose veins (VV) can contribute to the overexpression of matrix metalloproteinases (MMPs), affecting the endothelium, smooth muscle, and extracellular matrix of the vein wall. Gelatinases (MMP-2 and MMP-9), hypoxia, and inflammation occurring in the VV wall contribute to the increased expression of vascular endothelial growth factor (VEGF).

AIMS

Our objective was to analyze the concentration of gelatinases and VEGF in the great saphenous VV wall and plasma of patients.

METHODS

In total, 65 patients (2nd degree according to clinical state classification, etiology, anatomy, and pathophysiology-CEAP classification) aged 22 to 70 were enrolled. Control veins (n = 10) were collected from the patients who underwent coronary artery bypass graft surgery. Control plasma (n = 20) was obtained from healthy individuals. Gelatinases and VEGF levels were measured with the usage of ELISA method.

RESULTS

A significant increase in MMP-9 (11.2 vs. 9.98 ng/mg of protein) and VEGF (41.06 vs. 26 ng/g of protein) concentration in VV wall compared with control veins was observed. A positive correlation between VEGF versus MMP-2 (p = 0.03, r = 0.27) was found in the VV wall. However, no correlation was found between the concentration of VEGF and MMP-9 (p = 0.4, r = 0.11) in the VV wall. In addition, no statistical differences between MMP-9, MMP-2, and VEGF levels in plasma of VV patients compared with controls were noticed.

CONCLUSIONS

The results of the present study confirm that VV's patients have altered expression of MMPs and VEGF. Overexpression of MMP-9 and VEGF in the VV wall may contribute to the spreading of inflammatory process and suggests the intense remodeling of extracellular tissue within the VV wall.

Effect of a Peptide Construct on Differentiated Macrophage MMP-2 and MMP-9 Levels of Varicose Patients

BACKGROUND

The Matrix Metalloproteinase (MMPs) secreted from macrophages can affect the extracellular matrix remodeling process and improve varicose veins.

AIM

The aim of this study was to investigate the MMP-2 and MMP-9 gene expression and activity levels in the differentiated macrophages M2 of subjects with varicose veins, and to evaluate a peptide construct on their catalytic functions.

METHODS

The macrophages were differentiated from the monocytes using M-CSF. The MMP-2 and MMP-9 gene expression and activity levels were measured by RT-qPCR and Zymography techniques, respectively. A peptide construct (ESLCG) was predicted with bioinformatics tools, and was prepared for the study of enzyme functions as compared to Batimastat. Furthermore, the docking studies were obtained for the evaluation of interactions between peptide construct, Batimastat and enzyme 3D structures.

RESULTS

The results showed significant increases in MMP2 and MMP9 gene expression levels (P<0.001 and P<0.004, respectively) and gelatinolytic activities (P<0.001 and P<0.0001, respectively) in the macrophages. In agreement with the inhibitory effects of Batimastat, the peptide construct inhibited the MMP-2 and MMP-9 gelatinolytic activities up to 6.8 and 6.5 folds in the concentration of 150 µM. The docking analyses showed that the Lys187, Arg98, Leu49, Gly189, Leu190, Met97, Tyr53 and Phe57 residues of MMP-2 and the Leu187, His190, Glu402, His401, His405 and His411 residues of MMP-9 are interacted with the atoms of Batimastat and ESLCG peptide.

CONCLUSION

The ESLCG peptide may be applied as an inhibitor of MMP-2 and MMP-9 enzymes in the subjects with varicose veins.

Variability of MMP/TIMP and TGF-β1 Receptors throughout the Clinical Progression of Chronic Venous Disease

Chronic venous disease (CVeD) is a prevalent condition with a significant socioeconomic burden, yet the pathophysiology is only just beginning to be understood. Previous studies concerning the dysregulation of matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases (TIMPs)) within the varicose vein wall are inconsistent and disregard clinical progression. Moreover, it is highly plausible that MMP and TIMP expression/activity is affected by transforming growth factor (TGF)-β1 and its signaling receptors (TGFβRs) expression/activity in the vein wall. A case–control study was undertaken to analyze genetic and immunohistochemical differences between healthy (n = 13) and CVeD (early stages: n = 19; advanced stages: n = 12) great saphenous vein samples. Samples were grouped based on anatomic harvest site and subjected to quantitative polymerase chain reaction for MMP1, MMP2, MMP8, MMP9, MMP12, MMP13, TIMP1, TIMP2, TIMP3, TIMP4, TGFβR1, TGFβR2, and TGFβR3 gene expression analysis, and then to immunohistochemistry for immunolocalization of MMP2, TIMP2, and TGFβR2. Decreased gene expression of MMP12, TIMP2, TIMP3, TIMP4, and TGFβR2 was found in varicose veins when compared to controls. Regarding CVeD clinical progression, two facts arose: results across anatomical regions were uneven; decreased gene expression of MMP9 and TGFβR3 and increased gene expression of MMP2 and TIMP3 were found in advanced clinical stages. Most immunohistochemistry results for tunica intima were coherent with qPCR results. In conclusion, decreased expression of TGFβRs might suggest a reduction in TGF-β1 participation in the MMP/TIMP imbalance throughout CVeD progression. Further studies about molecular events in the varicose vein wall are required and should take into consideration the venous anatomical region and CVeD clinical progression.

The Histopathology of Varicose Vein Disease

Varicosity is a complex venous pathology affecting the lower extremities. The exact etiology and physiopathology of varicose vein disease remain, however, unclear. Several theories exist from incompetence of the valves to a disturbance of the smooth muscle cells (SMC) and extra-cellular matrix (ECM) organization providing a weakness of the venous wall. Multiple studies have been performed to explain the underlying mechanisms of varicosity inducing alterations in the expression patterns of the endothelium, SMC, and ECM. In that respect, most attention has been focused on the alteration of the endothelium due to blood stasis and hypoxia inducing migration/proliferation of the medial SMC into the intima. Also, studies in the deformation of the ECM induced by alterations of the expression patterns of the metalloproteinases (MMP) and their inhibitors (TIMPs) have been put forward to explain the etiology of varicosity. However, less attention has been paid to the hormonal changes that occur during pregnancy and menopause, crucial factors to be involved in the etiology of varicosity. Since alteration of the estrogen receptor-b (ERb) expression could enhance directly the cellular volume of SMC and thus the disorganization of the contractile-elastic units, hypertrophy of SMC must be accounted a pivotal role that could induce the weakness of the venous wall. Altogether, this review summarizes an overview of the latest findings of varicosity with respect to the histopathological changes of the different cellular components of the varicose vein wall related to functional and morphologic alterations.

Pathogenesis of Varicose Veins and Implications for Clinical Management

Varicose veins (VVs) classically result from venous hypertension owing to incompetence of the major communications between the superficial and deep veins of the lower extremity. In a significant number of patients, there is no demonstrable truncal saphenous reflux and varicosities are the result of isolated perforating and nonsaphenous vein incompetence. The clinical and histologic features of VVs are the result of disruption of the normal architectural structure of the venous wall as a consequence of remodeling of the extracellular matrix (ECM) in response to increased venous distention and altered hemodynamic shear stress. Although a number of genes, growth factors, proteases, and their inhibitors known to modulate the ECM have been implicated in the pathogenesis of VVs, their etiology remains unknown. The complex variations in venous anatomy in patients with VVs require detailed vein mapping to determine the source and drainage locations of reflux if the rates of residual and recurrent varicosities are to be reduced. The distinct pathogenic mechanisms involved in the development of VVs have important implications for the management of VVs that include a wide spectrum of treatment modalities ranging from reassurance, alternative medicines, conservative management or compression therapy, and surgical or endovascular therapy.

Effect of TGF-beta1 on MMP/TIMP and TGF-beta1 receptors in great saphenous veins and its significance on chronic venous insufficiency

Objectives

Transforming growth factor-beta1 (TGF-β1) may participate in local chronic inflammatory processes in varicose veins and in venous wall structure modifications through regulation of matrix metalloproteinases (MMP) and their inhibitors (tissue inhibitor of metalloproteinase (TIMP)). The aim of this study was to analyze the effect of TGF-β1 in the vein wall, namely on the gene expression of selected MMP, TIMP and TGF-β1 receptors.

Methods

Healthy vein samples were harvested from eight subjects who underwent coronary bypass graft surgery with great saphenous vein. Each vein sample was divided into two segments, which were cultivated separately in vitro (one of the segments had TGF-β1 added) and then submitted to gene expression analysis.

Results

In the TGF-β1 supplemented group, there was a general increase in the mean gene expression. Specifically, expression of MMP9, MMP12, TIMP1 and TIMP2 were statistically significant.

Conclusion

The results of this study demonstrate that the gene expression of MMP9, MMP12, TIMP1 and TIMP2 was influenced by the addition of TGF-β1. These results may be translated to chronic venous insufficiency framework and suggest involvement of TGF-β1 in the vein wall pathology.

Biomolecular mechanisms in varicose veins development

Varicose veins (VVs) can be described as tortuous and dilated palpable veins, which are more than 3 mm in diameter. They are one of the clinical presentations of chronic venous disorders, which are a significant cause of morbidity. The prevalence of VVs has been estimated at 25-33% in women and 10-20% in men and is still increasing at an alarming rate. Family history, older age, female, pregnancy, obesity, standing occupations, and a history of deep venous thrombosis are the predominant risk factors. A great amount of factors are implicated in the pathogenesis of VVs, including changes in hydrostatic pressure, valvular incompetence, deep venous obstruction, ineffective function of calf muscle pump, biochemical and structural alterations of the vessel wall, extracellular matrix abnormalities, impaired balance between growth factors or cytokines, genetic alterations, and several other mechanisms. Nevertheless, the issue of pathogenesis in VVs is still not completely known, even if a great progress has been made in understanding their molecular basis. This kind of studies appears promising and should be encouraged, and perhaps the new insight in this matter may result in targeted therapy or possibly prevention.

Matrix metalloproteinase inhibitors as investigative tools in the pathogenesis and management of vascular disease

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade various components of the extracellular matrix (ECM). MMPs could also regulate the activity of several non-ECM bioactive substrates and consequently affect different cellular functions. Members of the MMPs family include collagenases, gelatinases, stromelysins, matrilysins, membrane-type MMPs, and others. Pro-MMPs are cleaved into active MMPs, which in turn act on various substrates in the ECM and on the cell surface. MMPs play an important role in the regulation of numerous physiological processes including vascular remodeling and angiogenesis. MMPs may also be involved in vascular diseases such as hypertension, atherosclerosis, aortic aneurysm, and varicose veins. MMPs also play a role in the hemodynamic and vascular changes associated with pregnancy and preeclampsia. The role of MMPs is commonly assessed by measuring their gene expression, protein amount, and proteolytic activity using gel zymography. Because there are no specific activators of MMPs, MMP inhibitors are often used to investigate the role of MMPs in different physiologic processes and in the pathogenesis of specific diseases. MMP inhibitors include endogenous tissue inhibitors (TIMPs) and pharmacological inhibitors such as zinc chelators, doxycycline, and marimastat. MMP inhibitors have been evaluated as diagnostic and therapeutic tools in cancer, autoimmune disease, and cardiovascular disease. Although several MMP inhibitors have been synthesized and tested both experimentally and clinically, only one MMP inhibitor, i.e., doxycycline, is currently approved by the Food and Drug Administration. This is mainly due to the undesirable side effects of MMP inhibitors especially on the musculoskeletal system. While most experimental and clinical trials of MMP inhibitors have not demonstrated significant benefits, some trials still showed promising results. With the advent of new genetic and pharmacological tools, disease-specific MMP inhibitors with fewer undesirable effects are being developed and could be useful in the management of vascular disease.

Postthrombotic vein wall remodeling: preliminary observations

BACKGROUND

Postthrombotic syndrome is characterized by a fibrotic vein injury following deep vein thrombosis (DVT). We sought to quantify the change in vein wall thickness in patients who fail to resolve DVT by 6 months and whether there were differences in blood or plasma levels of inflammatory proteins associated with venous remodeling.

METHODS

Patients presenting with confirmed lower extremity DVT were prospectively recruited for this study. Duplex imaging of the lower extremity venous system was performed, and blood was collected at entrance and repeat evaluation with blood draw and ultrasound imaging at 1 and 6 months. DVT resolution and thickness of the vein wall was quantified by ultrasound imaging in each segment affected by thrombus, and a contralateral, unaffected vein wall served as a control. Gene and protein expression of inflammatory markers were examined from leukocytes and serum, respectively. Analysis of variance or Student t-tests were used, and a P < .05 was significant. N = 10 to 12 for all analyses.

RESULTS

Thirty-two patients (12 patients with DVT resolution at 6 months, 10 patients with persistent thrombus at 6 months, and 10 healthy controls) were compared. Both resolving and nonresolving DVT were associated with a 1.5- to 1.8-fold increased vein wall thickness at 6 months (P = .008) as compared with nonaffected vein wall segments. However, the thickness of the affected segments was 1.4-fold greater in patients who had total resolution of the DVT by 6 months than in patients who had persistent chronic thrombus 6 months after presentation (P = .01). There was a four- to five-fold increased level of matrix metalloproteinase-9 (MMP-9) antigen in thrombosed patients compared with nonthrombosed patient controls (P < .05), while Toll-like receptor-9 (TLR-9) gene expression was three-fold less than controls (P < .05) at enrollment. D-dimer and P-selectin were higher in thrombosed as compared to controls at diagnosis but not at 6 months. Both TLR-4 (marker of inflammation) and P-selectin gene expression were higher in leukocytes from patients with chronic DVT compared with those who resolved at 1 month after diagnosis (P < .05).

CONCLUSIONS

This preliminary study suggests ongoing vein wall remodeling after DVT, measurable by ultrasound and associated with certain biomarkers. At 6 months, the vein wall is markedly thickened and directly correlates with resolution. This suggests that the vein wall response is initiated early following thrombus formation and persists even in the presence of total resolution.

Pathogenesis of primary varicose veins

BACKGROUND

Valvular incompetence and reflux are common features of primary varicose veins, and have long been thought to be their cause. Recent evidence, however, suggests that changes in the vein wall may precede valvular dysfunction.

METHODS

A literature search was performed using PubMed and Ovid using the keywords 'varicose vein wall changes', 'pathogenesis', 'aetiology' and 'valvular dysfunction'. Articles discussing the pathophysiology of complications of varicose veins, such as ulceration, recurrence, thrombophlebitis and lipodermatosclerosis, were excluded.

RESULTS AND CONCLUSION

Positive family history, age, sex and pregnancy are important risk factors for varicose vein formation. Areas of intimal hyperplasia and smooth muscle cell proliferation are often noted in varicose veins, although regions of atrophy are also present. The total elastin content in varicose as opposed to non-varicose veins is reduced; changes in overall collagen content are uncertain. Matrix metalloproteinases (MMPs), including MMP-1, MMP-2, MMP-3, MMP-7 and MMP-9, and tissue inhibitor of metalloproteinase (TIMP) 1 and TIMP-3 are upregulated in varicose veins. Activation of the endothelium stimulates the recruitment of leucocytes and the release of growth factors, leading to smooth muscle cell proliferation and migration. Dysregulated apoptosis has also been demonstrated in varicose veins. An understanding of the pathophysiology of varicose veins is important in the identification of potential therapeutic targets and treatment strategies.

Prolonged increases in vein wall tension increase matrix metalloproteinases and decrease constriction in rat vena cava: Potential implications in varicose veins

BACKGROUND

Increased venous hydrostatic pressure plays a role in the pathogenesis of varicose veins. Increased expression of matrix metalloproteinases (MMPs) has been identified in varicose veins. Also, we have shown that MMP-2 inhibits venous contraction. However, the relation between venous pressure, MMP expression, and venous dysfunction is unclear. The purpose of this study was to test the hypothesis that prolonged increases in venous wall tension cause overexpression of MMPs and decreased contractility, which in turn promote venous dilation.

METHODS

Circular segments of inferior vena cava (IVC) were isolated from male Sprague-Dawley rats and suspended between two wires in Krebs solution. Preliminary vein wall tension-contraction relation showed maximal potassium chloride (KCl) (96 mmol/L) contraction at 0.5 g basal tension, which remained steady with increases in tension up to 2 g. Vein segments were subjected to either control (0.5 g) or high (2 g) basal tension for short (1 hour) or long duration (24 hours). Isometric contraction in response to phenylephrine (Phe, 10(-5) mol/L), angiotensin II (AngII, 10(-6) mol/L), and KCl was measured. The veins were frozen to determine the expression and localization of MMPs using immunoblots and immunohistochemistry.

RESULTS

In IVC segments subjected to 0.5 g tension for 1 hour, Phe and AngII produced significant contraction. At higher 2 g basal tension for 24 hours, both Phe and AngII contractions were significantly reduced. Reduction in KCl contraction was also observed at high 2 g basal tension for 24 hours, suggesting that the reduction in vein contraction is not specific to a particular receptor, and likely involves inhibition of a post-receptor contraction mechanism. In vein segments under 2 g tension for 24 hours and treated with TIMP-1, Phe, AngII, and KCl contractions were partially restored, suggesting the involvement of MMPs. IVC immunoblot analysis demonstrated prominent bands corresponding to MMP-2 and MMP-9 protein. High 2 g wall tension for 24 hours was associated with marked increase in the amount of MMP-2 and -9 relative to the housekeeping protein actin. There was a correlation between MMP expression and decreased vein contraction. Also, significant increases in MMP-2 and -9 immunostaining were observed in IVC segments subjected to high 2 g tension for 24 hours. Both MMP-2 and MMP-9 caused significant inhibition of Phe contraction in IVC segments.

CONCLUSIONS

In rat IVC, increases in magnitude and duration of wall tension is associated with reduced contraction and overexpression of MMP-2 and -9. In light of our findings that MMP-2 and -9 promote IVC relaxation, the data suggest that protracted increases in venous pressure and wall tension increase MMPs expression, which in turn reduce venous contraction and lead to progressive venous dilation.

Mechanisms of varicose vein formation: valve dysfunction and wall dilation

Varicose veins are a common venous disease of the lower extremity. Although the mechanisms and determinants in the development of varicosities are not clearly defined, recent clinical studies and basic science research have cast some light on possible mechanisms of the disease. In varicose veins, there are reflux and incompetent valves as well as vein wall dilation. Primary structural changes in the valves may make them ‘leaky’, with progressive reflux causing secondary changes in the vein wall. Alternatively, or concurrently, the valves may become incompetent secondary to structural abnormalities and focal dilation in vein wall segments near the valve junctions, and the reflux ensues as an epiphenomenon. The increase in venous pressure causes structural and functional changes in the vein wall that leads to further venous dilation. Increase in vein wall tension augments the expression/activity of matrix metalloproteinases (MMPs), which induces degradation of the extracellular matrix proteins and affect the structural integrity of the vein wall. Recent evidence also suggests an effect of MMPs on the endothelium and smooth muscle components of the vein wall and thereby causing changes in the venous constriction/relaxation properties. Endothelial cell injury also triggers leukocyte infiltration, activation and inflammation, which lead to further vein wall damage. Thus, vein wall dilation appears to precede valve dysfunction, and the MMP activation and superimposed inflammation and fibrosis would then lead to chronic and progressive venous insufficiency and varicose vein formation.

Current Advances in the Pathogenesis of Varicose Veins

Varicose veins have a wide prevalence and are characterized by their tortuous, dilated, and serpentine appearance. This pattern is the result of disruption of the normal arrangement of the extracellular matrix (ECM) and smooth muscle cells (SMC) in veins. Valvular incompetence and the effect of increased hydrostatic pressure have been implicated in the pathogenesis of varicose veins. Alterations in the ECM and varied expression of metalloproteinases and their inhibitors can effect changes in venous wall remodeling. Gene expression and specific candidate markers have been identified in varicose veins. Differential gene transcription may influence the adaptive response of the venous wall to stimuli and the remodeling of the ECM that leads to the development of varicose veins.

HMG-CoA reductase inhibitors reduce matrix metalloproteinase-9 activity in human varicose veins

Matrix metalloproteinases (MMPs) have been implicated in tissue degradation in varicose veins. The aim of this study was to investigate the effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) on the activity of MMPs in varicose veins. MMP-9 was present at significantly higher levels in varicose veins than in controls and was localized mainly in smooth muscle cells at the tunica media, where marked degradation of the extracellular matrix was observed. Both simvastatin and pravastatin strikingly suppressed MMP-9 activity in ex vivo culture of varicose veins. Simvastatin suppressed MMP-9 at both the mRNA and protein levels as well as at the urokinase-type plasminogen activator protein level, resulting in the dramatic suppression of MMP-9 activity induced by tumor necrosis factor-alpha. Therefore, statins suppress MMP-9 activity by multiple mechanisms in varicose veins, suggesting they may have clinical potential for the treatment of this disease.