von Willebrand factor: demographics of plasma protein level in a large blood donor cohort from South Wales in the United Kingdom

Dynamic and functional linkage between von Willebrand factor and ADAMTS-13 with aging: an Atherosclerosis Risk in Community study

BACKGROUND

von Willebrand factor (VWF) is a multimeric glycoprotein critically involved in hemostasis, thrombosis, and inflammation. VWF function is regulated by its antigen levels, multimeric structures, and the state of enzymatic cleavage. Population studies in the past have focused almost exclusively on VWF antigen levels in cross-sectional study designs.

OBJECTIVE

To identify subjects in the Atherosclerosis Risk in Community study who had persistently low and high VWF antigen over 10 years and to quantify longitudinal changes in the biological activities and cleavage of VWF in these subjects.

METHODS

We measured VWF antigen, propeptide, adhesive activities, and cleavage by ADAMTS-13 quantified using a mass spectrometry method that detected the cleaved VWF peptide EQAPNLVY, as well as coagulation factor VIII activity.

RESULTS

We determined the mean subject-specific increase in VWF to be 22.0 International Units (IU)/dL over 10 years, with 95% between -0.3 and 59.7 IU/dL. This aging-related increase was also detected in VWF propeptide levels, ristocetin cofactor activity, and VWF binding to collagen. We identified 4.1% and 25.0% of subjects as having persistently low (<50 IU/dL) and high (>200 IU/dL) VWF antigen, respectively. Subjects with persistently low VWF had enhanced ristocetin cofactor activity, whereas those with persistently high VWF had elevated levels of ADAMTS-13, resulting in a comparable rate of VWF cleavage between the 2 groups.

CONCLUSIONS

These results provide new information about the effects of aging on VWF antigens and adhesive activity and identify a functional coordination between VWF and the rate of its cleavage by ADAMTS-13.

Cadmium, von Willebrand factor and vascular aging

Vascular aging is a major contributing factor to cardiovascular disease. The aged blood vessels, characterized by vascular wall thickening and stiffening, are instigated by endothelial cell dysfunction induced by oxidative stress and inflammation. von Willebrand Factor (vWF) is a glycoprotein known for its role in coagulation, and plasma levels of vWF are increased with age. Elevated vWF promotes thrombosis, atherosclerotic plaque formation, inflammation and proliferation of vascular smooth muscle cells. Cadmium (Cd) is an environmental pollutant associated with increased morbidity and mortality of cardiovascular disease. At low concentrations, Cd activates pro-survival signaling in endothelial cells, however enhances intima-media thickness and atherogenesis. A non-cytotoxic dose of Cd also increases endothelial vWF expression and secretion in vivo and in vitro. In this review, we summarize the molecular mechanisms underlying vWF-promoted vascular aging-associated pathologies and Cd-induced vWF expression. In addition, we propose that exposure to low-dose Cd is a risk factor for vascular aging, through elevation of plasma vWF.

Pathophysiological Aspects of Aging in Venous Thromboembolism: An Update

The aim of this review is to highlight all the factors that associate venous thromboembolism (VTE) with aging. Elderly people are characterized by a higher incidence of thrombosis taking into account the co-existing comorbidities, complications and fatality that arise. Based on the Virchow triad, pathophysiological aspects of venous stasis, endothelium injury and hypercoagulability in elderly people (≥65 years) are described in detail. More precisely, venous wall structure, nitric oxide (NO) and endothelin-1 expression are impaired in this age group. Furthermore, an increase in high-molecular-weight kininogen (HMWK), prekallikrein, factors V, VII, VIII, IX and XI, clot lysis time (CLT) and von Willebrand factor (vWF) is observed. Age-dependent platelet dysfunction and changes in anticoagulant factors are also illustrated. A “low-grade inflammation stage” is delineated as a possible risk factor for thrombosis in the elderly. Consequently, clinical implications for frail elderly people related to diagnosis, treatment, bleeding danger and VTE recurrence emerge. We conclude that aging is an acquired thrombotic factor closely related to pathophysiological changes.

Age-Associated Increase in Thrombogenicity and Its Correlation with von Willebrand Factor

Endothelial cells that cover the lumen of all blood vessels have the inherent capacity to express both pro and anticoagulant molecules. However, under normal physiological condition, they generally function to maintain a non-thrombogenic surface for unobstructed blood flow. In response to injury, certain stimuli, or as a result of dysfunction, endothelial cells release a highly adhesive procoagulant protein, von Willebrand factor (VWF), which plays a central role in formation of platelet aggregates and thrombus generation. Since VWF expression is highly restricted to endothelial cells, regulation of its levels is among the most important functions of endothelial cells for maintaining hemostasis. However, with aging, there is a significant increase in VWF levels, which is concomitant with a significant rise in thrombotic events. It is not yet clear why and how aging results in increased VWF levels. In this review, we have aimed to discuss the age-related increase in VWF, its potential mechanisms, and associated coagulopathies as probable consequences.

Effects of a 1-Year Physical Activity Intervention on Markers of Hemostasis among Breast Cancer Survivors: A Randomized Controlled Trial

Introduction  Physical activity may reduce the development of breast cancer. Whereas hypercoagulability has been linked to adverse outcomes in breast cancer patients, the effects of physical activity on their hemostatic factors are unknown. The study aimed to assess whether long-term (1 year) physical activity can affect hemostatic factors in breast cancer patients. Methods  Fifty-five women (35-75 years) with invasive breast cancer stage I/II were randomized to a physical activity intervention ( n  = 29) lasting 1 year or to a control group ( n  = 26), and analyzed as intention to treat. Fibrinogen, factor VII antigen, tissue factor pathway inhibitor, and von Willebrand factor (VWF) antigen as well as prothrombin fragment 1 + 2, the endogenous thrombin potential and D-dimer, were measured in plasma before intervention (baseline), and then after 6 and 12 months. Results  Maximal oxygen uptake (measure of cardiorespiratory fitness) decreased the first 6 months among the controls, but remained stable in the intervention group. We found no significant differences between the two study groups regarding any of the hemostatic factors, except a significantly higher increase in factor VII antigen in the intervention group. The effect of the intervention on VWF was, however, significantly affected by menopausal stage, and a significant effect of the intervention was found on VWF among postmenopausal women, even after adjustment for dietary intake. Conclusion  Long-term physical activity had no effect on the majority of the hemostatic factors measured, but led to increased plasma concentrations of factor VII antigen and prevented an increase in VWF concentration after breast cancer treatment in postmenopausal women. The clinical impact of these findings for risk of vascular thrombosis warrants further studies.

[Detection and analysis of plasma VWF levels in healthy Chinese by automatic standardized assay]

Objective: To explore the normal range of plasma VWF levels of healthy Chinese and to analyze the influencing factors to VWF level. Methods: To detect the levels of von Willebrand factor antigen (VWF∶Ag) , von Willebrand factor ristocetin cofactor activity (VWF∶Rco) , von Willebrand factor collagen binding activity (VWF∶CB) , and the factor Ⅷ coagulation activity (FⅧ∶C) by using fully automatic and standardized testing instruments and matching reagent in 70 healthy Chinese. The effects of age, ABO blood type, gender and region were also analyzed. Meanwhile, 8 standard plasma samples (2 normal subjects, 6 cases of type 2 VWD) confirmed by NIBSC were tested for VWF values. Results: ① In 70 cases of healthy Chinese, the mean value of plasma VWF∶Ag, VWF∶Rco and VWF∶CB were (95.4±44.9) %, (105.9±35.4) % and (89.8±28.4) %, respectively; the ratio of VWF∶Rco/VWF∶Ag and VWF∶CB/VWF∶Ag was 1.18±0.25 and 1.03±0.29, respectively. ②There was no statistical significance in plasma VWF values between the age ≥30 years and <30 years group (P>0.05) . ③The VWF∶Rco, VWF∶CB of type O blood group were lower than that of non-O group (t=2.074, P=0.042; t=3.949, P=0.001) , but there was no statistical significance in VWF∶Ag, VWF∶Rco/VWF∶Ag, VWF∶CB/VWF∶Ag between the two groups (P>0.05) . ④There was no significant difference in VWF values between male and female groups (P>0.05) . ⑤The VWF∶Ag, VWF∶CB of the northern population (North area of Huaihe River) group were higher than that of southern population (Suzhou area) group (t=4.525, P=0.001; t=3.214, P=0.002) , but VWF∶Rco/VWF∶Ag, VWF∶CB/VWF∶Ag were lower than that of southern population group (t=6.373, P=0.001; t=2.902, P=0.005) , and there was no significant difference in VWF∶Rco between the two groups (t=1.598, P=0.115) . ⑥The VWF values of 8 standard plasma samples were in accordance with the known diagnosis. Conclusions: A more integrate plasma VWF levels of healthy Chinese people were obtained for the first time by using fully automatic and standardized testing instruments. It was also found that ABO blood group and region had a significant impact on the level of VWF, while the age and gender had no significant effect.