Current Advances in the Pathogenesis of Varicose Veins

Loci cg06256735 and cg15815843 in the MFAP5 gene regulatory regions are hypomethylated in varicose veins apparently due to active demethylation

Varicose vein disease (VVD) is a common health problem worldwide. Microfibril-associated protein 5 (MFAP5) is one of the potential key players in its pathogenesis. Our previous microarray analysis revealed the cg06256735 and cg15815843 loci in the regulatory regions of the MFAP5 gene as hypomethylated in varicose veins which correlated with its up-regulation. The aim of this work was to validate preliminary microarray data, estimate the level of 5-hydroxymethylcytosine (5hmC) at these loci, and determine the methylation status of one of them in different layers of the venous wall. For this, methyl- and hydroxymethyl-sensitive restriction techniques were used followed by real-time PCR and droplet digital PCR, correspondingly, as well as bisulfite pyrosequencing of +/- oxidized DNA. Our microarray data on hypomethylation at the cg06256735 and cg15815843 loci in whole varicose vein segments were confirmed and it was also demonstrated that the level of 5hmC at these loci is increased in VVD. Specifically, among other layers of the venous wall, tunica (t.) intima is the main contributor to hypomethylation at the cg06256735 locus in varicose veins. Thus, it was shown that hypomethylation at the cg06256735 and cg15815843 loci takes place in VVD, with evidence to suggest that it happens through their active demethylation leading to up-regulation of the MFAP5 gene, and t. intima is most involved in this biochemical process.

Pathophysiology and Genetic Associations of Varicose Veins: A Narrative Review

Varicose veins (VVs) have a high prevalence worldwide and have become a major medical burden. Their pathophysiology involves a complex interplay of inflammation and tissue remodeling, and current treatment is limited by its impact on the pathophysiological mechanisms. In addition, despite clear environmental factors, family history is an important risk factor, suggesting a genetic component to the risk of developing VVs. Our understanding of the pathogenesis of these diseases has benefited greatly from the expansion of population genetic studies, from pioneering family studies to large genome-wide association studies; we now find multiple risk loci for each venous disease. This review considers the pathophysiology of VVs, highlighting the current state of genetic knowledge. We also propose future directions for research.

Global impact and contributing factors in varicose vein disease development

Varicose veins are convoluted, expanded, and stretched subcutaneous veins of the lower leg and are the most frequently reported medical condition. This condition has a higher prevalence in Western and developed countries. Inadequacy of the valves results in reflux of blood in the veins of the lower leg. The present study aims to describe the epidemiology and contributing factors (risk factors and pathological factors) in the development of varicose veins disease. PubMed/Medline, Science Direct, Google Scholar, SciFinder, Scopus, and Web of Science databases were explored to include potential research and review articles. Finally, 65 articles were considered appropriate to include in the study. Pain, swelling, heaviness, and tingling of the lower limbs are the most common sign and symptoms caused by varicose veins while in some individuals it is asymptomatic. The Prevalence of varicose veins varies geographically. Currently, it is reported that globally about 2%–73% of the population is affected by varicose veins while the prevalence rate in Pakistan is 16%–20%. Different risk factors associated with the advancement of varicose veins are age, gender, occupation, pregnancy, family history, smoking, BMI and obesity, exercise, genetic factor, and current lifestyle. In varicose veins, some contributory elements may also play an important role in the disease development, incorporating constant venous wall aggravation, hereditary variation, and persistent venous hypertension. This condition has now turned into a curable issue that was previously viewed broadly as less important for treatment, determining the individual’s satisfaction. Moreover, the mechanisms behind the risk factors involve diet, physical work, and hormonal contribution. These are more likely to be explored.

Prevalence of Varicose Veins Among Nurses in Different Departments in Jazan Public Hospitals, Saudi Arabia: A Cross-Sectional Study

Varicose veins (VV) in the lower limbs are the most prevalent vascular condition in humans. They can cause significant signs and symptoms and, in extreme cases, death. This study aims to investigate the prevalence and identify the risk factors for varicose veins among nurses working in multiple departments at Jazan King Fahd Central Hospital and Prince Muhammad bin Nasser Hospital. A cross-sectional study was conducted by sending a questionnaire to female and male nurses in these hospitals. This study included 482 nurses, 415 (86.1%) of whom were female and 67 (13.9%) male. The prevalence of varicose veins among the nurses of both hospitals was 76 (15.8%), compared with 406 (84.2%) not diagnosed with varicose veins. The prevalence of varicose veins was 67 (88.2%) in female nurses, compared with 9 (11.8%) in male nurses. The risk factors associated with varicose veins were ethnicity (p = 0.007), carrying heavy items (p = 0.001), lack of exercise (p = 0.031), family history (p = 0.001), use of hormonal therapy (p = 0.001), use of contraceptive pills (p = 0.0035), type of delivery (p = 0.002), number of children (p = 0.004), and hours sitting per shift (p = 0.002). The comorbidities associated with varicose veins were deep vein thrombosis (p = 0.001), hypertension (p = 0.002), chronic constipation (p = 0.006), diabetes (p = 0.001), kidney disease (p = 0.001), rheumatoid arthritis (p = 0.001), coronary artery disease, and severe occupational injury to the lower extremities (p = 0.001). Nurses are responsible for most of the health system's services. Increasing the number of nursing workers for patient care, encouraging physical exercise, and lowering the pension age appear to be required to avoid the occurrence and development of varicose veins among nurses.

Mechanisms of Lower Extremity Vein Dysfunction in Chronic Venous Disease and Implications in Management of Varicose Veins

Chronic venous disease (CVD) is a common venous disorder of the lower extremities. CVD can be manifested as varicose veins (VVs), with dilated and tortuous veins, dysfunctional valves and venous reflux. If not adequately treated, VVs could progress to chronic venous insufficiency (CVI) and lead to venous leg ulcer (VLU). Predisposing familial and genetic factors have been implicated in CVD. Additional environmental, behavioral and dietary factors including sedentary lifestyle and obesity may also contribute to CVD. Alterations in the mRNA expression, protein levels and proteolytic activity of matrix metalloproteinases (MMPs) have been detected in VVs and VLU. MMP expression/activity can be modulated by venous hydrostatic pressure, hypoxia, tissue metabolites, and inflammation. MMPs in turn increase proteolysis of different protein substrates in the extracellular matrix particularly collagen and elastin, leading to weakening of the vein wall. MMPs could also promote venous dilation by increasing the release of endothelium-derived vasodilators and activating potassium channels, leading to smooth muscle hyperpolarization and relaxation. Depending on VVs severity, management usually includes compression stockings, sclerotherapy and surgical removal. Venotonics have also been promoted to decrease the progression of VVs. Sulodexide has also shown benefits in VLU and CVI, and recent data suggest that it could improve venous smooth muscle contraction. Other lines of treatment including induction of endogenous tissue inhibitors of metalloproteinases (TIMPs) and administration of exogenous synthetic inhibitors of MMPs are being explored, and could provide alternative strategies in the treatment of CVD.

IGFBP6 regulates vascular smooth muscle cell proliferation and morphology via cyclin E-CDK2

Despite the high prevalence of varicose veins, the underlying pathogenesis of this disease remains unclear. The present study aims to explore the role of insulin-like growth factor binding protein 6 (IGFBP6) in vascular smooth muscle cells (VSMCs). Using a protein array approach, we identified several differentially expressed proteins between varicose great saphenous veins and normal great saphenous veins. Bioinformatic analysis showed that IGFBP6 was closely related to cell proliferation. Further validation confirmed that IGFBP6 was one of the most highly expressed proteins in varicose vein tissue. Knocking down IGFBP6 in VSMCs significantly attenuated cell proliferation and induced the S phase arrest during the cell cycle. Further experiments demonstrated that IGFBP6 knockdown increased cyclin E ubiquitination, which reduced expression of cyclin E and phosphorylation of CDK2. Furthermore, IGFBP6 knockdown arrested centrosome replication, which subsequently influenced VSMC morphology. Ultimately, IGFBP6 was validated to be involved in VSMC proliferation in varicose vein tissues. The present study reveals that IGFBP6 is closely correlated with VSMC biological function and provides unprecedented insights into the underlying pathogenesis of varicose veins.

GPR30 Promotes the Phenotypic Switching of Vascular Smooth Muscle Cells via Activating the AKT and ERK Pathways

Background

Lower extremity varicose veins (LEVVs) are a common venous disorder of venous dilation and tortuosity. The functional integrity of vascular smooth muscle cells (VSMCs), the majority of the cells in venous tissues, and their phenotypic differences play important roles in the occurrence and development of LEVV. However, the underlying mechanism remains unclear.

Methods

The expression of estrogen receptors ERα and ERβ and G-protein-coupled receptor 30 (GPR30) in LEVV tissues and the role of GPR30 in VSMC phenotypic switching were examined by Western blotting and quantitative real-time PCR. Finally, the related mechanisms underlying LEVVs were explored by Western blotting.

Results

The serum estradiol content was increased in LEVV patients compared with normal control patients, but the mRNA levels of ERα and ERβ were not significantly different. GPR30 was overexpressed in LEVVs, and high expression of GPR30 promoted the maintenance of a synthetic phenotype in which OPN, MMP-1 and MMP-9 were highly expressed and α-SMA was poorly expressed in VSMCs. Finally, the mechanism by which GPR30 promotes the phenotypic switching of VSMCs is dependent on the ERK1/2 and AKT pathways.

Conclusion

GPR30 may contribute to the pathogenesis of LEVVs by promoting the maintenance of a synthetic phenotype in VSMCs by activating the ERK1/2 and AKT pathways, and GPR30 might be a novel therapeutic target for clinical LEVV treatment.

Clinical and Molecular Characterization of Classical-Like Ehlers-Danlos Syndrome Due to a Novel TNXB Variant

The Ehlers-Danlos syndromes (EDS) constitute a clinically and genetically heterogeneous group of connective tissue disorders. Tenascin X (TNX) deficiency is a rare type of EDS, defined as classical-like EDS (clEDS), since it phenotypically resembles the classical form of EDS, though lacking atrophic scarring. Although most patients display a well-defined phenotype, the diagnosis of TNX-deficiency is often delayed or overlooked. Here, we described an additional patient with clEDS due to a homozygous null-mutation in the TNXB gene. A review of the literature was performed, summarizing the most important and distinctive clinical signs of this disorder. Characterization of the cellular phenotype demonstrated a distinct organization of the extracellular matrix (ECM), whereby clEDS distinguishes itself from most other EDS subtypes by normal deposition of fibronectin in the ECM and a normal organization of the α5β1 integrin.

Disequilibrium in MMPs and the tissue inhibitor of metalloproteinases in different segments of the varicose great saphenous vein wall

BACKGROUND

Varicose great saphenous veins (VGSVs) are a common disorder with a high incidence, but the pathogenesis is unclear. This study was designed to measure the changes in matrix metalloproteinases (MMPs) and the tissue inhibitor of metalloproteinases (TIMPs) in different segments from VGSV walls to determine the relationship between MMPs, TIMPs expression, and expansion of the venous wall.

METHODS

Twenty-one VGSV and 12 normal great saphenous vein (GSV) specimens were collected. Venous walls in the two groups, expression of MMP-2, MMP-9, TIMP-1, and TIMP-2 proteins, protein-positive expression ratios, mRNA expression, and protein content were determined by immunohistochemistry, PCR, and western blot.

RESULTS

The MMP-2, MMP-9, TIMP-1, and TIMP-2 protein-positive expression ratios, mRNA expression in the upper, middle, and lower segments in the VGSV group were significantly higher than the corresponding regions in the GSV group, respectively. The MMP-2, MMP-9, TIMP-1, and TIMP-2 protein-positive expression ratios, mRNA expression, and protein concentrations in the lower segments in the VGSV group were also significantly higher than the upper and middle segments in the VGSV group and the corresponding regions in the GSV group, respectively.

CONCLUSIONS

Under high hemodynamics, disequilibrium of MMPs and TIMPs from VGSVs exists within the upper, middle, and lower segments of VGSVs. These results suggested that MMPs and TIMPs participate in the process of venous wall remodeling and may be one of the mechanisms associated with the formation and development in varicose veins.

Mechanical Properties of Diseased Veins

Extensive research exists on arterial mechanical properties and how they change in disease conditions, but substantially less is known about venous mechanics in healthy and disease states. Although the mechanics of both vessel types are determined by the unique layered composition of the vessel wall, the precise distribution of the layers differs greatly between arteries and veins. Thus, vein mechanics must be analyzed and understood independently from those of arteries. This review discusses the compositional attributes that are unique to veins, how these attributes contribute to venous mechanics, and the alterations that occur to both composition and material properties during venous thrombosis and insufficiency. In general, changes to the venous wall during thrombosis increase wall stiffness and decrease extensibility. During venous insufficiency, however, both the stiffness and the extensibility of the venous wall decrease. Characterizing these changes is essential to better understand disease progression and build vein-specific devices for treating venous disease.

DNA methylation and gene expression profiling reveal MFAP5 as a regulatory driver of extracellular matrix remodeling in varicose vein disease

AIM

To integrate transcriptomic and DNA-methylomic measurements on varicose versus normal veins using a systems biological analysis to shed light on the interplay between genetic and epigenetic factors.

MATERIALS & METHODS

Differential expression and methylation were measured using microarrays, supported by real-time quantitative PCR and immunohistochemistry confirmation for relevant gene products. A systems biological 'upstream analysis' was further applied.

RESULTS

We identified several potential key players contributing to extracellular matrix remodeling in varicose veins. Specifically, our analysis suggests MFAP5 acting as a master regulator, upstream of integrins, of the cellular network affecting the varicose vein condition. Possible mechanism and pathogenic model were outlined.

CONCLUSION

A coherent model proposed incorporates the relevant signaling networks and will hopefully aid further studies on varicose vein pathogenesis.

Venous stent placement ameliorates cutaneous microvascular function in iliocaval venous obstruction

BACKGROUND

The role of cutaneous microvascular dysfunction is well known in the development of chronic venous disease. However, the effects of venous obstruction on microcirculation have not been well investigated. The aim of this study was to assess cutaneous microvascular function in patients with iliocaval venous obstruction (ICVO) before and after venous stent placement.

METHODS

Endothelium-dependent and endothelium-independent vasodilator responses to iontophoretic administration of incremental doses of acetylcholine (ACh) and sodium nitroprusside (SNP) were evaluated using a laser Doppler scanner in the perimalleolar region in the supine and sitting positions in patients with ICVO (n = 11) and in healthy control subjects (n = 15). Cutaneous microvascular function, the Venous Clinical Severity Score (VCSS), and the Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) clinical class were re-evaluated 3 months after stent placement in patients with ICVO.

RESULTS

The vasodilatory responses to ACh and SNP in the cutaneous microcirculation were lower in patients with ICVO than in healthy subjects in the sitting position (P < .05). Recanalization and stent placement were successful in all patients in the evaluation of VCSS and clinical class, and a significant decrease was determined in the signs and symptoms of the venous disease (P < .01). Stent placement resulted in a significant increase in vasodilation response to both ACh and SNP in the supine position and no improvement in the sitting position in patients with ICVO.

CONCLUSIONS

ICVO impairs endothelium-dependent and endothelium-independent vasodilation in the perimalleolar region. Iliocaval venous stent placement may recover microvascular dysfunction at different levels.

Phenotypic and functional transformation in smooth muscle cells derived from varicose veins

OBJECTIVE

Varicose veins (VVs) are a common disorder of venous dilation and tortuosity, but the underlying mechanism is unclear. The functional integrity and phenotypic differences of VVs are also unclear. This study tested the hypothesis that phenotypic and functional differences exist between smooth muscle cells (SMCs) derived from VVs and normal veins.

METHODS

SMCs were isolated from 28 samples of varicose great saphenous veins (VGSVs) and normal great saphenous (NGSVs) and cultured. Proliferation, migration, adhesion, and aging capacity in SMCs were compared in the two veins. Bas, Bcl-2, caspase-3, matrix metalloproteinase (MMP)-2 MMP-9, tissue inhibitor of metalloproteinases (TIMP)-1, and TIMP-2 messenger (m)RNA expression and protein content were detected by fluorescence quantitative polymerase chain reaction and immunoblotting.

RESULTS

The microfilament structure of the framework was increased in SMCs in the VGSV group. Proliferation, migration, adhesion, and the aging cell count in SMCs in the VGSV group were significantly higher than the corresponding regions in the NGSV group (P < .05). Bas and caspase-3 mRNA expression and protein content were decreased, whereas Bcl-2 mRNA expression and protein content were increased in the VGSV group compared with the NGSV group (P < .05). MMP-2, MMP-9, TIMP-1, and TIMP-2 mRNA expression and protein content in the VGSV group were increased compared with the NGSV group (P < .05).

CONCLUSIONS

SMCs derived from VGSVs are more dedifferentiated and demonstrate increased proliferative and synthetic capacity. These results suggest the presence of phenotypic and functional differences between SMCs derived from VGSVs and NGSVs. The phenotypic and functional abnormalities in SMCs may be associated with the pathogenesis in VGSVs.

Matrix Metalloproteinases in Remodeling of Lower Extremity Veins and Chronic Venous Disease

The veins of the lower extremity are equipped with efficient wall, contractile vascular smooth muscle (VSM), and competent valves in order to withstand the high venous hydrostatic pressure in the lower limb and allow unidirectional movement of deoxygenated blood toward the heart. The vein wall structure and function are in part regulated by matrix metalloproteinases (MMPs). MMPs are zinc-dependent endopeptidases that are secreted as inactive pro-MMPs by different cells in the venous wall including fibroblasts, VSM, and leukocytes. Pro-MMPs are activated by other MMPs, proteinases, and other endogenous and exogenous activators. MMPs degrade various extracellular matrix (ECM) proteins including collagen and elastin, and could affect other cellular processes including endothelium-mediated dilation, VSM cell migration, and proliferation as well as modulation of Ca²⁺ signaling and contraction in VSM. It is thought that increased lower limb venous hydrostatic pressure increases hypoxia-inducible factors and other MMP inducers such as extracellular matrix metalloproteinase inducer, leading to increased MMP expression/activity, ECM protein degradation, vein wall relaxation, and venous dilation. Vein wall inflammation and leukocyte infiltration cause additional increases in MMPs, and further vein wall dilation and valve degradation, that could lead to chronic venous disease and varicose veins (VVs). VVs are often presented as vein wall dilation and tortuosity, incompetent venous valves, and venous reflux. Different regions of VVs show different MMP levels and ECM proteins with atrophic regions showing high MMP levels/activity and little ECM compared to hypertrophic regions with little or inactive MMPs and abundant ECM. Treatment of VVs includes compression stockings, venotonics, sclerotherapy, or surgical removal. However, these approaches do not treat the cause of VVs, and other lines of treatment may be needed. Modulation of endogenous tissue inhibitors of metalloproteinases (TIMPs), and exogenous synthetic MMP inhibitors may provide new approaches in the management of VVs.

Femoropopliteal Bypass with Varicose Greater Saphenous Vein

Surgical bypass for peripheral arterial occlusive disease can be performed using different graft materials. Autogenous greater saphenous vein (GSV) is the treatment of choice because of its superior long-term patency. We report a case of femoropopliteal bypass with varicose GSV in a 77-year-old man who was presented with limb ischemia and both varicose veins. We successfully performed bypass with varicose vein. He has been doing well for 15 months after the operation, and a computed tomography angiography of the lower leg, performed on the 15th postoperative month, demonstrated widely patent femoropopliteal bypass graft and no structural change.

Galectin-3 inhibition ameliorates hypoxia-induced pulmonary artery hypertension

Galectin-3 (Gal-3) is a β-galactoside-binding lectin, which is important in inflammation, fibrosis and heart failure. The present study aimed to investigate the role and mechanism of Gal-3 in hypoxia-induced pulmonary arterial hypertension (PAH). Male C57BL/6J and Gal-3^−/− mice were exposed to hypoxia, then the right ventricular systolic pressure (RVSP) and Fulton's index were measured, and Gal-3 mRNA and protein expression in the pulmonary arteries was analyzed by reverse transcription-quantitative polymerase chain reaction and western blotting. Compared with the control, hypoxia increased the mRNA and protein expression levels of Gal-3 in wild type murine pulmonary arteries. Gal-3 deletion reduced the hypoxia-induced upregulation of RVSP and Fulton's index. Furthermore, human pulmonary arterial endothelial cells (HPAECs) and human pulmonary arterial smooth muscle cells (HPASMCs) were stimulated by hypoxia in vitro, and Gal-3 expression was inhibited by small interfering RNA. The inflammatory response of HPAECs, and the proliferation and cell cycle distribution of HPASMCs was also analyzed. Gal-3 inhibition alleviated the hypoxia-induced inflammatory response in HPAECs, including tumor necrosis factor-α and interleukin-1 secretion, expression of intercellular adhesion molecule-1 and adhesion of THP-1 monocytes. Gal-3 inhibition also reduced hypoxia-induced proliferation of HPASMCs, partially by reducing cyclin D1 expression and increasing p27 expression. Furthermore, Gal-3 inhibition suppressed HPASMC switching from a ‘contractile’ to a ‘synthetic’ phenotype. In conclusion, Gal-3 serves a fundamental role in hypoxia-induced PAH, and inhibition of Gal-3 may represent a novel therapeutic target for the treatment of hypoxia-induced PAH.

Matrix Metalloproteinases as Regulators of Vein Structure and Function: Implications in Chronic Venous Disease

Lower-extremity veins have efficient wall structure and function and competent valves that permit upward movement of deoxygenated blood toward the heart against hydrostatic venous pressure. Matrix metalloproteinases (MMPs) play an important role in maintaining vein wall structure and function. MMPs are zinc-binding endopeptidases secreted as inactive pro-MMPs by fibroblasts, vascular smooth muscle (VSM), and leukocytes. Pro-MMPs are activated by various activators including other MMPs and proteinases. MMPs cause degradation of extracellular matrix (ECM) proteins such as collagen and elastin, and could have additional effects on the endothelium, as well as VSM cell migration, proliferation, Ca(2+) signaling, and contraction. Increased lower-extremity hydrostatic venous pressure is thought to induce hypoxia-inducible factors and other MMP inducers/activators such as extracellular matrix metalloproteinase inducer, prostanoids, chymase, and hormones, leading to increased MMP expression/activity, ECM degradation, VSM relaxation, and venous dilation. Leukocyte infiltration and inflammation of the vein wall cause further increases in MMPs, vein wall dilation, valve degradation, and different clinical stages of chronic venous disease (CVD), including varicose veins (VVs). VVs are characterized by ECM imbalance, incompetent valves, venous reflux, wall dilation, and tortuosity. VVs often show increased MMP levels, but may show no change or decreased levels, depending on the VV region (atrophic regions with little ECM versus hypertrophic regions with abundant ECM) and MMP form (inactive pro-MMP versus active MMP). Management of VVs includes compression stockings, venotonics, and surgical obliteration or removal. Because these approaches do not treat the causes of VVs, alternative methods are being developed. In addition to endogenous tissue inhibitors of MMPs, synthetic MMP inhibitors have been developed, and their effects in the treatment of VVs need to be examined.

Increased levels of lysosomal cysteinyl cathepsins in human varicose veins: a histology study

Varicose veins are a major chronic venous disease characterised by extensive remodelling of the extracellular matrix architecture in the vascular wall. Although matrix metalloproteinases have been implicated in these pathologic events, little is known about the functional relevance of other protease family members. Here, we studied the distribution of lysosomal cysteine proteases, cathepsins B, L, K, and S, and their endogenous inhibitor, cystatin C, in long saphenous vein specimens from nine normal donors and 18 patients with varicose veins (VVs). Immunohistochemical analysis demonstrated increased levels of cathepsins L, K, B, and S and reduced levels of cystatin C in VVs. This imbalance between cysteinyl cathepsins and cystatin C may favour VV remodelling. To investigate the inflammatory mechanism of their expression, we examined a detailed inflammatory cell profile in VVs, including macrophages, T lymphocytes, and mast cells. Increased numbers of CD3-positive T cells and tryptase-positive mast cells were found in VVs, and enhanced levels of cysteinyl cathepsins were detected from lesion CD3-positive T cells, chymase-positive mast cells, endothelial cells, and smooth-muscle cells. Elevated cathepsins, and their co-localisation to infiltrated inflammatory cells and to vascular cells, suggest that these proteases participate in extracellular matrix degradation in response to inflammation during VV pathogenesis.

Analysis of the association between an insertion/deletion polymorphism within the 3' untranslated region of COL1A2 and chronic venous insufficiency

BACKGROUND

Chronic venous insufficiency (CVI) is a common cause of leg pain and swelling and is commonly associated with varicose veins. It has significant socioeconomic consequences and is among the most common problems encountered in surgical practice. Although our current understanding of the pathogenesis of CVI is far from clear, there is a growing body of evidence suggesting a genetic contribution to the etiology of CVI.

METHODS

By analyzing 254 CVI cases and 508 healthy controls in a Chinese population, we used a candidate gene approach to evaluate the association between a 7-base pair insertion/deletion (indel) polymorphism (rs3917) in the 3' untranslated region (3'UTR) of the alpha-2 type I collagen gene (COL1A2) and CVI susceptibility. Logistic regression was used to analyze the association between rs3917 and CVI risk, adjusted for sex and age. Computational modeling was used to predict potential molecular mechanisms underlying the association.

RESULTS

Logistic regression analysis revealed that subjects carrying indel or deletion/deletion genotypes had a significantly increased risk for CVI than individuals carrying insertion/insertion genotypes (adjusted odds ratio, 1.64; 95% confidence interval [CI], 1.10-2.45; P = 0.010). Carrying the 7-base pair deletion allele was associated with a 1.60-fold risk for CVI (95% CI, 1.11-2.31; P = 0.008). Computational modeling suggests that the rs3917 insertion allele lies within a predicted binding site (seed region) for microRNA-382 and that the deletion allele alters the affinity of microRNA-mRNA binding by disrupting the local structure of COL1A2 mRNA, presumably allowing for upregulated COL1A2 expression.

CONCLUSIONS

Taken together, our data suggest that common genetic variations in COL1A2 may influence CVI risk, possibly through microRNA-382-mediated regulation. Replication of our studies in other populations will strengthen our understanding of this association.

Finite Element simulation of buckling-induced vein tortuosity and influence of the wall constitutive properties

The mechanisms giving rise to vein tortuosity, which is often associated with varicosis, are poorly understood. Recent works suggest that significant biological changes in the wall of varicose veins may precede the mechanical aspects of the disease. To test the hypothesis of tortuosity being a consequence of these changes, a Finite Element model was developed based on previous experimental work on vein buckling. The model was then used to evaluate the effect of alterations of the mechanical behavior of the wall on tortuosity onset and severity. The results showed that increasing anisotropy toward the circumferential direction promotes tortuosity. An increase in wall stiffness tends to decrease the level of tortuosity but interestingly, if the vein segment is little or not pre-stretched such increase will not prevent, or it will even promote, the onset of tortuosity. These results provide additional arguments supporting the hypothesis of tortuosity being the consequence of biologically-induced changes in the varicose vein wall. Based on a 3D model of the leg and in vivo identification of the material properties of varicose veins, a clinical validation of these findings is being developed.

Morphological characteristics of the walls of thrombophlebitic saphenous vein

Introduction: To investigate the morphological changes in the walls of thrombophlebitic saphenous veins.

Methods: Fifty-four specimens were made into slices for haematoxylin and eosin and Masson trichrome staining; ultrathin slices were also created. Slices were observed under light microscopy and electron microscopy.

Results: Under light microscopy, the tunica intima of venous wall in the thrombophlebitic saphenous veins group was obviously thickened and incomplete; intravascular papillary endothelial hyperplasia was observed. Hyperplasia of collagenous fibres in the tunica media was observed. Elastic fibres in the tunica externa became fewer, whereas nourishing vessels were significantly increased in number. Infiltration of many inflammatory cells was observed. Under electron microscopy, Auer bodies with high electron density and round granules could be seen in endothelial cells in the thrombophlebitic saphenous veins group. Smooth muscle cells had an irregular karyotype, with blurred cristae in some mitochondria. Myofilaments basically disappeared.

Conclusion: Thrombus formation might aggravate re-modelling of the walls of varicose veins.

A genetic study of chronic venous insufficiency

BACKGROUND

Chronic venous insufficiency (CVI) is an important cause of morbidity in Western countries. The aim of this study is to demonstrate the heredity of CVI, focusing on molecular and genetic aspects of the disease.

METHODS

The study depended on the recruitment of informative families, accurate determination of the phenotype of each family member, and blood sample for DNA extraction for genetic analysis. Each family member was invited to attend a vascular consultation. A genealogical tree for each recruited family was composed. Then, a peripheral blood sample for DNA extraction from each member of the recruited families was obtained for genetic evaluation.

RESULTS

By the evaluation of genealogical trees, it was evident that CVI segregates, in all families studied, in an autosomal dominant mode with incomplete penetrance. In nine families studied, varicose veins were linked to the candidate marker D16S520 on chromosome 16q24, which may account for the linkage to FOXC2.

CONCLUSION

In our study, in families with affected patients with the D16S520 marker, there was evidence of saphenofemoral junction reflux. The fact that there is linkage to a candidate marker for the FOXC2 gene suggests there is a functional variant within, or in the vicinity of, which predisposes to varicose veins. Further studies are necessary to identify genes and mechanism so as to achieve better understanding of the genetic basis of CVI.

Analysis of vascular endothelial growth factor gene expression in the tissues of patients with chronic venous insufficiency

OBJECTIVE

Immunohistochemical techniques have revealed the presence of vascular endothelial growth factor (VEGF) in the epidermis of patients with chronic venous disease (CVD). Our objective was to perform a quantitative analysis of the VEGF gene transcription in tissues that are potential sources of this factor (skin, varicose veins [VV] and great saphenous vein [GSV]) in patients with CVD.

METHODS

In all, 212 skin and venous tissue samples were collected from patients diagnosed with CVD and controls. The VEGF gene expression was analysed using quantitative realtime polymerase chain reaction (PCR).

RESULTS

The skin VEGF expression was lower in the CVD group than in the control group (P = 0.04). There were no significant differences between the insufficient GSV of the CVD group and the control healthy vein (P = 0.22). There was a greater expression of VEGF in the VV of the CVD group than in the control healthy vein (P = 0.03). Comparison of the VEGF expression between the different tissue types in the CVD group revealed significant differences between the skin and GSV (P = 0.02) and between the skin and the VV (P = 0.004), and between the VV and the GSV (P = 0.02).

CONCLUSIONS

The results of the present study show an over-expression of VEGF gene in the VV tissue of patients with CVD. Based on the data in patients with C2 disease, the VVs appear to be the source of increased VEGF expression.

Influence of thrombophlebitis on TGF-β1 and its signaling pathway in the vein wall

Extensive extracellular matrix remodeling of the vein wall is involved in varicose veins pathogenesis. This process is controlled by numerous factors, including peptide growth factors. The aim of the study was to evaluate influence of thrombophlebitis on TGF-β1 and its signaling pathway in the vein wall. TGF-β1 mRNAlevels, growth factor content and its expression were evaluated by RT-PCR, ELISA, and western blot methods, respectively, in the walls of normal veins, varicose veins and varicose veins complicated by thrombophlebitis. Western blot analysis was used to assess TGF-β receptor type II (TGF-β RII) and p-Smad2/3 protein expression in the investigated material. Unchanged mRNA levels of TGF-β1, decreased TGF-β1 content, as well as decreased expression of latent and active forms of TGF-β1 were found in varicose veins. Increased expression of TGF-β RII and p-Smad2/3 were found in varicose veins. Thrombophlebitis led to increased protein expression of the TGF-β1 active form and p-Smad2/3 in the vein wall compared to varicose veins. TGF-β1 may play a role in the disease pathogenesis because of increased expression and activation of its receptor in the wall of varicose veins. Thrombophlebitis accelerates activation of TGF-β1 and activity of its receptor in the varicose vein wall.

Desmuslin gene knockdown causes altered expression of phenotype markers and differentiation of saphenous vein smooth muscle cells

OBJECTIVE

Phenotypic alterations of vascular smooth muscle cells (VSMCs) appear critical to the development of primary varicose veins. Previous study indicated desmuslin, an intermediate filament protein, was differentially expressed in smooth muscle cells (SMCs) isolated from varicose veins; thus, it was naturally hypothesized that altered desmuslin expression might in turn affect the functioning of VSMCs, leading to the phenotypic alterations and varicose vein development.

METHODS

In this study, expression of desmuslin in normal human saphenous vein SMCs was knocked down using small interfering RNA (siRNA), and control cells were treated with a scrambled siRNA sequence. The levels of several phenotypic markers including smooth muscle (SM) alpha-actin and smooth muscle myosin heavy chain (SM-MHC) were assessed. Collagen formation, matrix metalloproteinase expression (MMP-2), and cytoskeletal and morphological changes were also examined.

RESULTS

SMCs treated with desmuslin siRNA exhibited significantly increased levels of collagen synthesis and MMP-2 expression and decreased expression levels of SM alpha-actin, SM-MHC, and smoothelin and exhibited disassembly of actin stress fibers when compared with the control cells. Changes in cell morphology and actin fiber networks in VSMCs treated with desmuslin siRNA were consistent with a lower degree of differentiation.

CONCLUSIONS

These results indicated desmuslin expression is required for the maintenance of VSMC phenotype. Decreased desmuslin expression may affect differentiation of VSMCs and ultimately contribute to the development of varicose veins.

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.

Polymorphism of matrix metalloproteinase genes (MMP1 and MMP3) in patients with varicose veins

BACKGROUND

Several risk factors for varicose veins have been identified: female gender, combined with obesity and pregnancy, occupations requiring standing for long periods, sedentary lifestyle, history of deep-vein thrombosis and family history. However, no specific gene variants related to a wide prevalence of varicosities in general population have been identified. Extracellular matrix composition, predominantly maintained by matrix metalloproteinases (MMPs), may affect the vein-wall structure, which may lead to dilation of vessels and cause varicosities.

AIMS

MMP-1 (tissue collagenase I) and MMP-3 (stromelysin I) expression was found to be raised in varicose veins compared with normal vessels. Therefore, a study was conducted to evaluate a potential association between MMP1 and MMP3 promoter polymorphisms and a risk of varicose veins.

METHODS

Genotyping for the presence of the polymorphisms -1607dupG (rs1799750) in MMP1 and -1171dupA (rs3025058) in the MMP3 promoter region was performed using PCR and restriction-fragment length polymorphism assays in a group of 109 patients diagnosed with varicose veins and 112 healthy controls.

RESULTS

The frequencies of the MMP1 and MMP3 alleles (minor allele frequency 0.440 in patients vs. 0.451 in the controls for MMP1-1607*G and 0.514 vs. 0.469 for MMP3-1171*dupA, respectively) and of genotypes did not differ significantly between patients and controls.

CONCLUSIONS

The MMP1-1607dupG and MMP3-1171dupA promoter polymorphisms are not valuable markers of susceptibility for varicose veins.

Endothelial function impairment in chronic venous insufficiency: effect of some cardiovascular protectant agents

In segments of human varicose veins, endothelial function was assessed by measuring relaxation induced by acetylcholine in noradrenaline-precontracted preparations. In addition, concentration-response curves to acetylcholine were obtained before and after incubation with the arterial endothelium protectant agents captopril, losartan, troglitazone, pravastatin, or simvastatin. The antivaricose agent escin was also tested. Mean acetylcholine-induced relaxation of varicose venous rings was about 13%, approximately one third of that reported for control saphenous veins. Concentration-response curves to acetylcholine were ''u'' shaped, the result of endothelium-mediated relaxation at low concentrations, superseded by subsequent smooth muscle contractile responses. Relaxation was enhanced by the endothelium-protecting agents and by escin, troglitazone being the least, and simvastatin the most effective. It was concluded that endothelial dysfunction is present in varicose veins, that this anomaly can be reverted by cardiovascular protecting agents, and that it can play a role in the pathogenesis and treatment of chronic venous insufficiency.

Impaired microvascular endothelial function is restored by acute lower-limb exercise in post-surgical varicose vein patients

Evidence exists that cutaneous microvascular endothelial dysfunction persists in patients following varicose vein surgery. This study compared cutaneous microvascular function between post-surgical varicose vein patients and healthy controls and investigated whether any impairment of function can be attenuated by acute lower-limb exercise. Cutaneous flux responses of the gaiter area were measured in supine and standing positions before and after a 25-min walk using laser Doppler fluximetry and incremental-dose administration of acetylcholine (ACh) and sodium nitroprusside (SNP). The pre-exercise peak responses to ACh (standing) were lower in patients than controls (48+/-11 vs. 96+/-28 PU; P=0.032), whereas treadmill exercise abolished this difference (P=0.819). In contrast, the pre-exercise responses to SNP (standing) appeared higher in patients than controls (3 mC responses: 24+/-4 vs. 10+/-2 PU, respectively; P=0.023), with no effect of acute exercise (P>0.05). These findings suggest that acute treadmill exercise augments microvascular endothelial function in post-surgical varicose vein patients to levels observed in age-matched controls.