Polymorphisms of genes involved in inflammation and blood vessel development influence the risk of varicose veins

Vicious Circle With Venous Hypertension, Irregular Flow, Pathological Venous Wall Remodeling, and Valve Destruction in Chronic Venous Disease: A Review

Substantial advances occurred in phlebological practice in the last two decades. With the use of modern diagnostic equipment, the patients' venous hemodynamics can be examined in detail in everyday practice. Application of venous segments for arterial bypasses motivated studies on the effect of hemodynamic load on the venous wall. New animal models have been developed to study hemodynamic effects on the venous system. In vivo and in vitro studies revealed cellular phase transitions of venous endothelial, smooth muscle, and fibroblastic cells and changes in connective tissue composition, under hemodynamic load and at different locations of the chronically diseased venous system. This review is an attempt to integrate our knowledge from epidemiology, paleoanthropology and anthropology, clinical and experimental hemodynamic studies, histology, cell physiology, cell pathology, and molecular biology on the complex pathomechanism of this frequent disease. Our conclusion is that the disease is initiated by limited genetic adaptation of mankind not to bipedalism but to bipedalism in the unmoving standing or sitting position. In the course of the disease several pathologic vicious circles emerge, sustained venous hypertension inducing cellular phase transitions, chronic wall inflammation, apoptosis of cells, pathologic dilation, and valvular damage which, in turn, further aggravate the venous hypertension.

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.

CASZ1: Current Implications in Cardiovascular Diseases and Cancers

Castor zinc finger 1 (CASZ1) is a C2H2 zinc finger family protein that has two splicing variants, CASZ1a and CASZ1b. It is involved in multiple physiological processes, such as tissue differentiation and aldosterone antagonism. Genetic and epigenetic alternations of CASZ1 have been characterized in multiple cardiovascular disorders, such as congenital heart diseases, chronic venous diseases, and hypertension. However, little is known about how CASZ1 mechanically participates in the pathogenesis of these diseases. Over the past decades, at first glance, paradoxical influences on cell behaviors and progressions of different cancer types have been discovered for CASZ1, which may be explained by a "double-agent" role for CASZ1. In this review, we discuss the physiological function of CASZ1, and focus on the association of CASZ1 aberrations with the pathogenesis of cardiovascular diseases and cancers.

NLRC5 modulates phenotypic transition and inflammation of human venous smooth muscle cells by activating Wnt/β-catenin pathway via TLR4 in varicose veins

In varicose veins, abnormal phenotypic transition and inflammatory response is commonly found in venous smooth muscle cells (VSMCs). We aimed to explore the potential role and mechanism of NLRC5 exerted on VSMCs phenotypic transition and inflammation. NLRC5 expression was detected in varicose veins and platelet-derived growth factor (PDGF)-induced VSMCs by RT-qPCR and Western bolt assays. A loss-of-function assay was performed to evaluate the effects of NLRC5 knockdown on VSMC proliferation, migration, and phenotypic transition. ELISA was used to detect the contents of pro-inflammatory cytokines in the supernatant. The modulation of NLRC5 on TLR4 expression and Wnt/β-catenin signaling was also evaluated. We found that the expressions of NLRC5 in varicose veins and PDGF-induced VSMCs were upregulated. NLRC5 knockdown inhibited VSMC proliferation and migration. Extracellular matrix transformation was blocked by downregulating NLRC5 with increasing SM-22α expression and MMP-1/TIMP-1 ratio, as well as decreasing OPN and collagen I expressions. Besides, NLRC5 silencing reduced the contents of inflammatory cytokines. Furthermore, we found that NLRC5 regulated TLR4 expression, as well as subsequently activation of Wnt/β-catenin pathway and nuclear translocation of β-catenin, which was involved in NLRC5-mediated phenotypic transition and inflammatory in VSMCs. In conclusion, silencing NLRC5 depressed VSMCs' phenotypic transition and inflammation by modulating Wnt/β-catenin pathway via TLR4. This may provide a theoretical basis for treatment of varicose veins.

Mendelian randomization analysis of plasma levels of CD209 and MICB proteins and the risk of varicose veins of lower extremities

Varicose veins of lower extremities (VVs) are a highly prevalent condition, the pathogenesis of which is still not fully elucidated. Mendelian randomization (MR) can provide useful preliminary information on the traits that are potentially causally related to the disease. The aim of the present study is to replicate the effects of the plasma levels of MHC class I polypeptide-related sequence B (MICB) and cluster of differentiation 209 (CD209) proteins reported in a previous hypothesis-free MR study. We conducted MR analysis using a fixed effects inverse-variance weighted meta-analysis of Wald ratios method. For MICB and CD209, we used data from a large-scale genome-wide association study (GWAS) for plasma protein levels (N = 3,301). For VVs, we used GWAS data obtained in the FinnGen project (N = 128,698), the eMERGE network (phase 3, N = 48,429), and the UK Biobank data available in the Gene ATLAS (N = 452,264). The data used in the study were obtained in individuals of European descent. The results for MICB did not pass criteria for statistical significance and replication. The results for CD209 passed all statistical significance thresholds, indicating that the genetically predicted increase in CD209 level is associated with increased risk of VVs (βMR (SE) = 0.07 (0.01), OR (95% CI) = 1.08 (1.05-1.10), P-value = 5.9 ×10-11 in the meta-analysis of three cohorts). Our findings provide further support that CD209 can potentially be involved in VVs. In future studies, independent validation of our results using data from more powerful GWASs for CD209 measured by different methods would be beneficial.

CEAP clinical classes C0S-C4: differences, similarities and role of Ruscus + HMC + vitamin C in patients with chronic venous disease

Since the publication of the CEAP classification, new research has enriched our knowledge; notably on the heritability of CVD and the genetic and environmental factors involved in this condition, as well as the symptoms apparent within the spectrum of the CEAP clinical classes and the benefits of medical treatment. Using the CEAP classification as a special theme, a symposium with the same title as the present paper was held at the annual meeting of the 2019 European Venous Forum. The lectures presented much valuable information, from which some key points can be extracted. The influence of environmental factors was demonstrated, and the fact that a large amount of information can be obtained from comprehensive history taking. There is robust evidence for heritability. Many candidate genes/loci have been identified, potentially offering new targets for treatment. More research is needed, notably using genome-wide association studies and also on microbiota, which may play a role in CVD through the inflammation pathway. Ruscus + HMC + vitamin C acts by increasing venous and lymphatic tone, protecting microcirculation, and reducing inflammation. It improves quality of life in C0S to C3 CVD patients, while a review of clinical studies and a meta-analysis have confirmed its clinical efficacy across a wide spectrum of CVD clinical classes: C0S, C1S, C2, C3 and C4. It has been awarded a Grade 1A recommendation by the international guidelines.

[Ultrastructural characteristics of the mechanisms of varicose transformation of veins of different localization]

The contemporary interpretation of the pathogenesis of varicose vein transformation in young patients indicates the genetically determined pattern of this process. According to the diagnostic criteria proposed by T.I. Kadurina, varicose veins of different localization belong to the so-called minor phenomena of undifferentiated connective tissue dysplasia (UCTD) syndrome. However, its impact on the development of varicose vein transformation is taken into account by not all researchers probably due to the fact that its clinical manifestations remain somewhat unclear.

OBJECTIVE

To prove the role of UCTD syndrome in the development of varicose transformation of veins, by examining their wall biopsy specimens at the ultrastructural level.

MATERIAL AND METHODS

Vein wall fragments removed from 25 male patients were examined; their mean age was 19 years. All the patients were divided into 3 groups: 1) cases of left-sided varicocele (VC), 2) those of varicose veins in the lower extremities (VVLE), 3) control cases. Electron microscopy examination (EME) and morphometric and statistical analyses were performed.

RESULTS AND DISCUSSION

EME showed similar changes in the vein wall biopsy specimens obtained from both pediatric and adult patients with VC and VVLE. Analysis of the qualitative parameters of collagen fiber bundles revealed considerable differences in their thickness compared to those in the control group; the phenomenon of structural chaos; variability of their number in the bundles; uneven bundle thickness; abruptness of individual fibers due to their tortuous course; bundle disorganization areas and an expanded part of interfiber spaces. Morphometric analysis demonstrated a pronounced variability of numerical series when measuring their bundle thickness. The above changes indicate primary incompetence of the connective tissue framework of the varicose vein walls. The measurements of smooth muscle cells showed a decrease in their volume compared to that in the control group; there was an excessive proliferation of connective tissue between them. No substantial difference was found in the arithmetic mean of the measurements in different degrees of VC and VVLE and in the age groups for these diseases.

CONCLUSION

The ultrastructural analysis and morphometric results confirm the key role of UCTD syndrome in the pathogenesis of VC and VVLE and make it possible to combine these diseases into one - systemic varicose veins.

[Venous wall weackness pathogenesis in varicose vein disease]

Varicose veins of lower extremities, varicocele and varicose dilation of pelvic veins including ovaricovaricocele are the most common non-inflammatory diseases of venous system. The same mechanisms determined varicose dilatation regardless localization of the vein. First of all, these are wall weakness and valvular insufficiency combined with hereditary collagen fiber defectiveness in case of undifferentiated connective tissue syndrome. Imbalance between different types of collagen in vascular wall (especially types I and III) also results wall weakness. Other important mechanisms are smooth muscle cells dysfunction followed by excessive intracellular synthesis and intramuscular fibrosis and imbalance of protease system due to overproduction of metalloproteinases. We consider that different forms of varicose veins (varicose veins of lower extremities, varicocele, ovaricovaricocele) may be unified within one pathology (varicose vein disease).

A variant of the castor zinc finger 1 (CASZ1) gene is differentially associated with the clinical classification of chronic venous disease

Recent reports have suggested a reproducible association between the rs11121615 SNP, located within an intron of the castor zinc finger 1 (CASZ1) gene, and varicose veins. This study aimed to determine if this variant is also differentially associated with the various clinical classifications of chronic venous disease (CVD). The rs11121615 SNP was genotyped in two independent cohorts from New Zealand (n = 1876 controls /1606 CVD cases) and the Netherlands (n = 1626/2966). Participants were clinically assessed using well-established CVD criteria. The association between the rs11121615 C-allele and varicose veins was validated in both cohorts. This was strongest in those with higher clinical severity classes and was not significant in those with non-varicose vein CVD. Functional analysis of the rs11121615 variant demonstrated that the risk allele was associated with increased enhancer activity. This study demonstrates that the CASZ1 gene associated C-allele of rs11121615 has a significant, reproducible, association with CVD (CEAP C ≥ 2 meta-odds ratio 1.31, 95% CI 1.27–1.34, P = 1 × 10⁻⁹⁸, PHet = 0.25), but not with non-varicose vein (CEAP C1, telangiectasia or reticular veins) forms of venous disease. The effect size of this association therefore appears to be susceptible to influence by phenotypic heterogeneity, particularly if a cohort includes a large number of cases with lower severity CVD.

Expression profile of tRNA‑derived fragments and their potential roles in human varicose veins

Varicose veins (VVs) is a common disease presenting with chronic venous insufficiency. tRNA-derived fragments (tRFs) are associated with a variety of pathological conditions. However, the functions of tRFs in VVs have not been elucidated to date. The present study aimed to identify the key tRFs and investigate their potential roles in VVs. Small RNA sequencing (RNA-seq) was performed to investigate the expression of tRFs in tissues of patients with VVs and their matched adjacent normal veins tissues (ANVs). Reverse transcription-quantitative PCR (RT-qPCR) was used to confirm the differential expression of tRFs. A total of 13,789 tRFs were identified by small RNA-seq, including 45 differentially expressed tRFs (DETs), which comprised 14 upregulated and 31 downregulated tRFs in VV tissues compared with ANVs. In addition, DETs were mainly involved in the function of epidermal growth factor receptor and vascular endothelial growth factor receptor signaling pathways in VVs. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the target genes of DETs were predominantly involved in Wnt and mitogen-activated protein kinase (MAPK) signaling pathways, as well as calcium signaling. Additionally, two upregulated tRFs (tRF-36-F900BY4D84KRIME and tRF-23-87R8WP9IY) and one downregulated tRF (tRF-40-86J8WPMN1E8Y7Z2R) were further validated by RT-qPCR, and a signaling pathway regulation network of their target genes confirmed their involvement in the calcium, Wnt and MAPK signaling pathways. The results of the present study identified three DETs (tRF-36-F900BY4D84KRIME, tRF-23-87R8WP9IY and tRF-40-86J8WPMN1E8Y7Z2R), which may have crucial roles in the occurrence and progression of VVs by regulating Wnt and MAPK signaling, as well as calcium signaling. The present results may provide a basis for further investigation of the functional roles of tRFs in VVs.

Varicose veins of lower extremities: Insights from the first large-scale genetic study

Varicose veins of lower extremities (VVs) are a common multifactorial vascular disease. Genetic factors underlying VVs development remain largely unknown. Here we report the first large-scale study of VVs performed on a freely available genetic data of 408,455 European-ancestry individuals. We identified the 12 reliably associated loci that explain 13% of the SNP-based heritability, and prioritized the most likely causal genes CASZ1, PIEZO1, PPP3R1, EBF1, STIM2, HFE, GATA2, NFATC2, and SOX9. VVs-associated variants within these loci exhibited pleiotropic effects on several phenotypes including blood pressure/hypertension and blood cell traits. Gene set enrichment analysis revealed gene categories related to abnormal vasculogenesis. Genetic correlation analysis confirmed known epidemiological associations between VVs and deep venous thrombosis, weight, rough labor, and standing job, and found a genetic overlap with multiple traits that have not been previously suspected to share common genetic background with VVs. These traits included educational attainment, fluid intelligence and prospective memory scores, walking pace (negative correlation with VVs), smoking, height, number of operations, pain, and gonarthrosis (positive correlation with VVs). Finally, Mendelian randomization analysis provided evidence for causal effects of plasma levels of MICB and CD209 proteins, and anthropometric traits such as waist and hip circumference, height, weight, and both fat and fat-free mass. Our results provide novel insight into both VVs genetics and etiology. The revealed genes and proteins can be considered as good candidates for follow-up functional studies and might be of interest as potential drug targets.

Varicose veins of lower extremities (VVs) affect about 30% of adults in developed countries and cause both cosmetic and health problems. A strong body of evidence indicates that heredity plays an important role in the etiology of this condition. However, genetic basis of VVs remains poorly understood. Here, we present the results of the first large-scale genetic study for VVs. We identified genes which are the most likely involved in VVs pathogenesis. We show that VVs are correlated at a genetic level with numerous traits and phenotypes, including those already known from prior epidemiological studies (deep venous thrombosis, body mass index, standing job, etc.) as well as with those that have not been suspected to share common genetic background with VVs (fluid intelligence and prospective memory scores, smoking, walking pace, pain all over the body, and other traits). Finally, using genetic variants as instruments, we demonstrate direct causal effects of the traits related to anthropometry, such as height and weight, and plasma levels of immune-related proteins MICB and CD209. Our study provides novel insight into both VVs genetics and etiology. The revealed genes (CASZ1, PIEZO1, PPP3R1, EBF1, STIM2, HFE, GATA2, NFATC2, and SOX9) and proteins (MICB and CD209) can be considered as good candidates for follow-up functional studies and might be of interest as potential drug targets.