Influence of ADAMTS13 deficiency on venous thrombosis in mice

ADAMTS13 inhibits H2O2-induced human venous endothelial cell injury to attenuate deep-vein thrombosis by blocking the p38/ERK signaling pathway

Deep vein thrombosis (DVT) is a common complication in hematologic malignancies and immunologic disorders. Endothelial cell injury and dysfunction comprise the critical contributor for the development of DVT. A disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13), a plasma metalloprotease that cleaves von Willebrand factor, acts as a critical regulator in normal hemostasis. This study was aimed to explore the role of ADAMTS13 in endothelial cell injury during DVT and the possible mechanism. First, human umbilical vein endothelial cells (HUVECs) were exposed to hydrogen peroxide (H2O2). Then, the mRNA and protein expressions of ADAMTS13 were evaluated with the reverse transcription-quantitative polymerase chain reaction and western blot. After treatment with recombinant ADAMTS13 (rADAMTS13; rA13), the viability and apoptosis of H2O2-induced HUVECs were assessed by cell counting kit-8 assay and terminal-deoxynucleoitidyl transferase-mediated nick end labeling staining. In addition, the levels of prostaglandin F1-alpha, endothelin-1, and reactive oxygen species were detected using the enzyme-linked immunosorbent assay and dichloro-dihydro-fluorescein diacetate assay. The expressions of proteins related to p38/extracellular signal-regulated kinase (ERK) signaling pathway were estimated with the western blot. Then, p79350 (p38 agonist) was used to pretreat cells to analyze the regulatory effects of rA13 on p38/ERK signaling in H2O2-induced HUVEC injury. The results revealed that ADAMTS13 expression was significantly downregulated in H2O2-induced HUVECs. The reduced viability and increased apoptosis of HUVECs induced by H2O2 were revived by ADAMTS13. ADAMTS13 also suppressed the oxidative stress in HUVECs after H2O2 treatment. Besides, ADAMTS13 was found to block p38/ERK signaling pathway, and p79350 reversed the impacts of ADAMTS13 on the damage of HUVECs induced by H2O2. To sum up, ADAMTS13 could alleviate H2O2-induced HUVEC injury through the inhibition of p38/ERK signaling pathway.

Impact of the von Willebrand factor-ADAMTS-13 axis on the risk of future venous thromboembolism

BACKGROUND

von Willebrand factor (VWF) and its cleaving protease, ADAMTS-13, form a pivotal axis that regulates hemostasis. However, the role of the VWF-ADAMTS-13 axis in the risk of future venous thromboembolism (VTE) is unknown.

OBJECTIVES

To investigate whether plasma ADAMTS-13 levels and an imbalance with VWF levels, assessed as the VWF/ADAMTS-13 ratio, are associated with the risk of future VTE.

PATIENTS/METHODS

A population-based nested case-control study, comprising 383 incident VTE cases and 780 age- and sex-matched controls, was derived from the Tromsø study cohort (1994-2007). Antigen levels of ADAMTS-13 and VWF were measured in plasma samples obtained at cohort baseline. Odds ratios (ORs) with 95% CIs were estimated according to quartile cutoffs of ADAMTS-13 and VWF/ADAMTS-13 ratio determined in controls.

RESULTS

In age- and sex-adjusted analysis, ADAMTS-13 levels were inversely associated with the VTE risk, with an OR of 1.40 (95% CI, 0.99-1.99) for the lowest vs highest quartiles. The VWF/ADAMTS-13 ratio was linearly associated with the VTE risk (P for trend = .001), with an OR of 1.70 (95% CI, 1.19-2.43) for the highest vs lowest quartiles, and the association was particularly pronounced for unprovoked VTE (OR, 2.81; 95% CI, 1.65-4.81). The ORs were only slightly attenuated after additional adjustments for body mass index and C-reactive protein.

CONCLUSIONS

Lowered ADAMTS-13 levels and an imbalance between ADAMTS-13 and VWF levels, reflected by an increased VWF/ADAMTS-13 ratio, were associated with an increased risk of future VTE. Our findings suggest that the VWF-ADAMTS-13 axis is involved in the pathogenesis of VTE.

von Willebrand Factor Is a Critical Mediator of Deep Vein Thrombosis in a Mouse Model of Diet-Induced Obesity

OBJECTIVE

Obesity is characterized by chronic low-grade inflammation and consequentially a hypercoagulable state, associating with an increased incidence of venous thromboembolism. Increased VWF (von Willebrand factor) plasma concentration and procoagulant function are independent risk factors for venous thromboembolism and are elevated in obese patients. Here, we explore the pathobiological role of VWF in obesity-associated venous thrombosis using murine models. Approach and Results: We first showed that diet-induced obese mice have increased VWF plasma levels and FVIII (factor VIII) activity compared with littermate controls. Elevated VWF levels appeared to be because of both increased synthesis and impaired clearance. Diet-induced obesity-associated venous thrombosis was assessed using the inferior vena cava-stenosis model of deep vein thrombosis. Diet-induced obese mice developed larger venous thrombi that were rich in VWF, erythrocytes, and leukocytes. Administering a polyclonal anti-VWF antibody or an anti-VWF A1 domain nanobody was protective against obesity-mediated thrombogenicity. Delayed administration (3 hours post-inferior vena cava stenosis) similarly reduced thrombus weight in diet-induced obese mice.

CONCLUSIONS

This study demonstrates the critical role of VWF in the complex, thrombo-inflammatory state of obesity. It adds to the growing rationale for targeting VWF-specific interactions in thrombotic disease.

Plasminogen Tochigi mice exhibit phenotypes similar to wild-type mice under experimental thrombotic conditions

Plasminogen (Plg) is a precursor of plasmin that degrades fibrin. A race-specific A620T mutation in Plg, also known as Plg-Tochigi, originally identified in a patient with recurrent venous thromboembolism, causes dysplasminogenemia with reduced plasmin activity. The Plg-A620T mutation is present in 3–4% of individuals in East Asian populations, and as many as 50,000 Japanese are estimated to be homozygous for the mutant 620T allele. In the present study, to understand the changes of thrombotic phenotypes in individuals with the mutant 620T allele, we generated knock-in mice carrying the homozygous Plg-A622T mutation (Plg^T/T), an equivalent to the A620T mutation in human Plg. Plg^T/T mice grew normally but showed severely reduced plasmin activity activated by urokinase, equivalent to ~8% of that in wild-type mice. In vitro fibrin clot lysis in plasma was significantly slower in Plg^T/T mice than in wild-type mice. However, all experimental models of electrolytic deep vein thrombosis, tissue factor-induced pulmonary embolism, transient focal brain ischaemic stroke, or skin-wound healing showed largely similar phenotypes between Plg^T/T mice and wild-type mice. Protein S-K196E mutation (Pros1^E/E) is a race-specific genetic risk factor for venous thromboembolism. Coexistence in mice of Plg^T/T and Pros1^E/E did not affect pulmonary embolism symptoms, compared with those in Pros1^E/E mice. Hence, the present study showed that the Plg-A622T mutation, which confers ~8% plasmin activity, does not increase the risk of thrombotic diseases in mice under experimental thrombotic conditions and does not modify the thrombotic phenotype observed in Pros1^E/E mice. Plg^T/T mice can be used to investigate the potential pathophysiological impact of the Plg-A620T mutation.

Exacerbated venous thromboembolism in mice carrying a protein S K196E mutation

Protein S (PS) acts as an anticoagulant cofactor for activated protein C in regulation of blood coagulation. The K196E mutation in PS is a race-specific genetic risk factor for venous thromboembolism with a prevalence of ∼2% within the Japanese population. To evaluate the thrombosis risk of the PS-K196E mutation, we generated PS-K196E knockin mice and heterozygous PS-deficient mice. We analyzed their thrombotic states, comparing with mice carrying the factor V Leiden mutation (FV-R504Q), a race-specific genetic risk for venous thrombosis in whites. PS-K196E mice grew normally but had decreased activated protein C cofactor activity in plasma. Purified recombinant murine PS-K196E showed the same decreased activated protein C cofactor activity. A deep vein thrombosis model of electrolytic inferior vena cava injury and pulmonary embolism models induced by infusion of tissue factor or polyphosphates revealed that PS-K196E mice, heterozygous PS-deficient mice, and FV-R504Q mice were much more susceptible to venous thrombosis compared with wild-type mice. Transient middle cerebral artery ischemia-reperfusion injury model studies demonstrated that both PS-K196E mice and heterozygous PS-deficient mice had cerebral infarction similar to wild-type mice, consistent with human observations. Our in vitro and in vivo results support a causal relationship between the PS-K196E mutation and venous thrombosis and indicate that PS-K196E mice can provide an in vivo evaluation system to help uncovering racial differences in thrombotic diseases.