Arterialization and anomalous vein wall remodeling in varicose veins is associated with upregulated FoxC2-Dll4 pathway

Abstract

Varicose veins of lower extremities are a heritable common disorder. Mechanisms underlying its pathogenesis are still vague. Structural failures such as valve weakness and wall dilatation in saphenous vein result in venous retrograde flow in lower extremities of body. Reflux of blood leads to distal high venous pressure resulting in distended veins. In an earlier study, we observed a positive association between c.-512C4T FoxC2 gene polymorphism and upregulated FoxC2 expression in varicose vein specimens. FoxC2 overexpression in vitro in venous endothelial cells resulted in the elevated mRNA expression of arterial endothelial markers such as Delta-like ligand 4 (Dll4) and Hairy/enhancer-of-split related with YRPW motif protein 2 (Hey2). We hypothesized that an altered FoxC2-Dll4 signaling underlies saphenous vein wall remodeling in patients with varicose veins. Saphenous veins specimens were collected from 22 patients with varicose veins and 20 control subjects who underwent coronary artery bypass grafting. Tissues were processed for paraffin embedding and sections were immunostained for Dll4, Hey2, EphrinB2, a-SMA, Vimentin, and CD31 antigens and examined under microscope. These observations were confirmed by quantitative real-time PCR and western blot analysis. An examination of varicose vein tissue specimens by immunohistochemistry indicated an elevated expression of Notch pathway components, such as Dll4, Hey2, and EphrinB2, and smooth muscle markers, which was further confirmed by gene and protein expression analyses. We conclude that the molecular alterations in Dll4-Hey2 signaling are associated with smooth muscle cell hypertrophy and hyperplasia in varicose veins. Our observations substantiate a significant role for altered FoxC2-Dll4 signaling in structural alterations of saphenous veins in patients with varicose veins. In conjunction with the presence of genes conferring disease susceptibility, various risk factors, such as prolonged standing, an increased body mass index, and preganancy, increases the mean venous pressure, in the lower extremities. 3,4 Pfisterer et al in 2014 found in an experimental mouse model that an escalated venous filling pressure induces varicose-like venous remodeling. This process to a greater extent mimics detrimental remodeling processes observed in human varicose veins. 5 The precise molecular mechanisms underlying the pathogenesis and progression of varicose veins are unclear. We have earlier observed a significant association of FoxC2 c.-512C4T polymorphism with the presence of varicose veins in patients. FoxC2 was also upregulated at both transcript and protein levels in varicose vein tissues of patients with varicose veins. 6 In venous endothelial cells transfected with FoxC2-overexpressing mammalian vectors, the presence of putative arterial endothelial markers Delta-like ligand 4 (Dll4) and Hairy/enhancer-of-split related with YRPW motif protein 2 (Hey2) were found.

Lower extremity varicose veins in childhood and at a young age: Mechanism of development and specific features

“…Изучение фрагментов вен 22 больных с ВБВНК и иммуногистохимическое исследование выявили повышенную экспрессию в образцах стенок вен Dll4, Hey2, EphrinB2 и гладкомышечных маркеров. Авторы пришли к выводу, что молекулярные изменения в передаче сигналов Dll4 -Hey2 вызывают как гипертрофию, так и гиперплазию гладкомышечных клеток, что в конечном итоге приводит к изменениям структуры стенок вен в ответ на их варикозное расширение и несостоятельность дренажной функции [18]. Некоторые авторы указывают на то, что точечные мутации FoxC2 типа «сдвига рамки», такие как делеция, встраивание или замещение одного или нескольких нуклеотидов в ДНК, могут приводить к увеличению объема венозного рефлюкса в венах нижних конечностей и способствовать их варикозной трансформации [19].…”

Differentially Expressed Genes in Varicose Veins Disease: Current State of the Problem, Analysis of the Published Data

“…Интересные результаты получены в работах группы авторов S. Surendran и соавт. [26,27]. И на уровне мРНК, и на уровне белков была показана активация компонентов сигнального пути FOXC2-Dll4-Notch-Hey2, генерирующего пролиферативный сигнал, для гладкомышечных клеток.…”

Serum from Varicose Patients Induces Senescence‐Related Dysfunction of Vascular Endothelium Generating Local and Systemic Proinflammatory Conditions

“…Although the role of dysfunctional endothelium in the development of varicose veins is well established [9], the effect of varicosity on endothelial cell biology and, indirectly, on the endothelium-related pathophysiology of varicose vein complications remains elusive. In order to address this issue in a comprehensive manner we compared in this paper serum from patients with varicose veins and from healthy age-matched volunteers in terms of its effect on such critical, functional features of endothelial cells, like proliferation, senescence, production of reactive oxygen species (ROS), and secretory properties.…”