Von Willebrand factor processing in patients with advanced chronic liver disease and its relation to portal hypertension and clinical outcome

BACKGROUND AND AIMS

Endothelial dysfunction and portal hypertension (PH) are reflected by increased von Willebrand factor antigen (VWF-Ag) levels in advanced chronic liver disease (ACLD). This study investigated VWF release and cleavage and their association with PH and clinical outcomes.

METHODS

Levels of VWF-Ag, VWF-N (VWF-propeptide), and VWF-A (VWF processed by the main VWF-cleaving protease ADAMTS13) were assessed in 229 patients with clinically stable ACLD (hepatic venous pressure gradient [HVPG] ≥ 6 mmHg; absence of bacterial infections or acute decompensation) undergoing HVPG-measurement. Liver-healthy individuals served as controls (n = 24).

RESULTS

VWF-Ag and VWF-N were similarly accurate for the identification of clinically significant PH (CSPH; HVPG ≥ 10 mmHg) in compensated ACLD (AUROC: VWF-Ag 0.748; VWF-N 0.728). ADAMTS13 activity was similar between patients with ACLD and controls and did not correlate with PH and disease severity, whereas VWF cleavage decreased in patients with CSPH (i.e., VWF-Ag/-A-ratio increased). In vitro VWF activity strongly reflected VWF-Ag levels (Spearman's r = 0.874, p < 0.001), but decreased (vs. controls) in patients with CSPH when normalized to VWF-Ag levels (VWF-activity/-Ag-ratio). VWF-Act/-Ag ratio correlated negatively with ADAMTS13 activity (r =- 0.256, p < 0.001). ADAMTS13 activity was independently predictive for (i) portal vein thrombosis (PVT) and (ii) hepatic decompensation or liver-related death.

CONCLUSIONS

VWF-Ag levels and its propeptide are similarly suitable surrogates of PH in patients with compensated ACLD. ADAMTS13-Act was not linked to disease and PH severity, however, when normalized to VWF-Ag, both VWF cleavage and VWF activity were decreased in patients with CSPH, as compared to liver-healthy individuals. Low ADAMTS13-Act was associated with presumably more procoagulant VWF and adverse outcomes.

CLINICAL TRIAL NUMBER

NCT03267615.

Novel biomarker genes for the prediction of post-hepatectomy survival of patients with NAFLD-related hepatocellular carcinoma

BACKGROUND

The incidence and prevalence of nonalcoholic fatty liver disease related hepatocellular carcinoma (NAFLD-HCC) are rapidly increasing worldwide. This study aimed to identify biomarker genes for prognostic prediction model of NAFLD-HCC hepatectomy by integrating text-mining, clinical follow-up information, transcriptomic data and experimental validation.

METHODS

The tumor and adjacent normal liver samples collected from 13 NAFLD-HCC and 12 HBV-HCC patients were sequenced using RNA-Seq. A novel text-mining strategy, explainable gene ontology fingerprint approach, was utilized to screen NAFLD-HCC featured gene sets and cell types, and the results were validated through a series of lab experiments. A risk score calculated by the multivariate Cox regression model using discovered key genes was established and evaluated based on 47 patients' follow-up information.

RESULTS

Differentially expressed genes associated with NAFLD-HCC specific tumor microenvironment were screened, of which FABP4 and VWF were featured by previous reports. A risk prediction model consisting of FABP4, VWF, gender and TNM stage were then established based on 47 samples. The model showed that overall survival in the high-risk score group was lower compared with that in the low-risk score group (p = 0.0095).

CONCLUSIONS

This study provided the landscape of NAFLD-HCC transcriptome, and elucidated that our model could predict hepatectomy prognosis with high accuracy.

Focused panel sequencing points to genetic predisposition in non-cirrhotic intrahepatic portal hypertension patients in India

OBJECTIVE

Non-cirrhotic intrahepatic portal hypertension (NCIPH), a portal microangiopathy affecting small portal vein radicles, is a disease of Indian sub-continent. NCIPH appears to be a complex disease with interactions between inherited and acquired factors, though the exact pathophysiological mechanism is unknown. We aimed at investigating the genetic variants that might contribute to susceptibility to NCIPH.

METHODS

In this case-control study, we analyzed genes associated with microangiopathy-VWF-ADAMTS13 (von Willebrand factor and its cleavase enzyme - a disintegrin and matrix metalloprotease with thrombospondin type-1 motifs member 13) and alternative complement system vitamin B12 metabolism and with familial NCIPH.

RESULT

Eighty-four Indian patients with liver biopsy-proven NCIPH (cases) and 103 healthy controls (matched for residential region of India) were included in the study. Targeted next-generation sequencing (NGS) panel, comprising 11 genes of interest, was done on 54 cases. Genotyping of selected variants was performed in 84 cases and 103 healthy controls. We identified variants in MBL2, CD46 and VWF genes either associated or predisposing to NCIPH. We also identified a single case with a novel compound heterozygous mutation in MBL2 gene, possibly contributing to development of NCIPH.

CONCLUSION

In this first of a kind comprehensive gene panel study, multiple variants of significance have been noted, especially in ADAMTS13-VWF and complement pathways in NCIPH patients in India. Functional significance of these variants needs to be further studied.

Whole-Exome Sequencing in a Family with an Unexplained Tendency for Venous Thromboembolism: Multicomponent Prediction of Low-Frequency Variant Deleteriousness and of Individual Protein Interaction

Whole-exome sequencing (WES) in families with an unexplained tendency for venous thromboembolism (VTE) may favor detection of low-frequency variants in genes with known contribution to hemostasis or associated with VTE-related phenotypes. WES analysis in six family members, three of whom affected by documented VTE, filtered for MAF < 0.04 in 192 candidate genes, revealed 22 heterozygous (16 missense and six synonymous) variants in patients. Functional prediction by multi-component bioinformatics tools, implemented by a database/literature search, including ClinVar annotation and QTL analysis, prioritized 12 missense variants, three of which (CRP Leu61Pro, F2 Asn514Lys and NQO1 Arg139Trp) were present in all patients, and the frequent functional variants FGB Arg478Lys and IL1A Ala114Ser. Combinations of prioritized variants in each patient were used to infer functional protein interactions. Different interaction patterns, supported by high-quality evidence, included eight proteins intertwined in the "acute phase" (CRP, F2, SERPINA1 and IL1A) and/or in the "fibrinogen complex" (CRP, F2, PLAT, THBS1, VWF and FGB) significantly enriched terms. In a wide group of candidate genes, this approach highlighted six low-frequency variants (CRP Leu61Pro, F2 Asn514Lys, SERPINA1 Arg63Cys, THBS1 Asp901Glu, VWF Arg1399His and PLAT Arg164Trp), five of which were top ranked for predicted deleteriousness, which in different combinations may contribute to disease susceptibility in members of this family.

Reticuloendothelial activation and phenotypic alteration of peripheral monocytes with enhanced liver recruitment drive liver injury secondary to yellow phosphorus

BACKGROUND AND AIM

Monocytes and macrophages play a crucial role in the pathogenesis of acute liver failure (ALF). We aimed to study reticuloendothelial activation and its correlation with disease severity in commonly encountered yellow phosphorus (rodenticide)-induced hepatotoxicity patients. We also studied peripheral monocyte phenotype in a subset of patients.

METHODS

Reticuloendothelial activation markers were analyzed and correlated with disease severity score in a prospectively collected database of yellow phosphorus-related hepatoxicity patients between 2018 and 2021. In a prospective cohort of these patients and age-matched healthy controls, peripheral blood monocyte phenotyping was performed.

RESULTS

Reticuloendothelial activation markers were analyzed in 67 patients [Age: 23(12-64) years; median (range), men: 25, acute liver injury (ALI): 38, ALF: 29, model for end-stage liver disease (MELD) score: 28 (7-40)] of yellow phosphorus-induced hepatotoxicity. Serum ferritin (927; 10.3-34 807 ng/mL), sCD163 (4.59; 0.11-12.7 μg/mL), sCD25 (3050; 5.6-17 300 pg/mL) and plasma von Willebrand factor (423.5, 103-1106 IU/dL) were increased and showed significant correlation with liver disease severity assessed by MELD score (ρ = 0.29, ρ = 0.6, ρ = 0.56 and ρ = 0.46 respectively). Phenotyping and serum immune markers were performed in seven patients (M: 4; age: 27, 15-37 years; median, range; MELD score: 36, 21-40) and compared with eight healthy controls. Increase in classical monocytes and decrease in patrolling and intermediate monocyte subsets were observed in ALF cohort. HLA-DRlow CD163hi (immune exhaustion), CD64hi (immune complex-mediated response), and CCR2hi (liver homing) monocyte phenotype was noted.

CONCLUSION

Altered peripheral monocyte phenotype with enhanced liver homing and macrophage activation, suggests important role of innate immune activation, and provides a potential therapeutic target, in yellow phosphorus-induced hepatotoxicity.

Laboratory diagnosis of von Willebrand disease in the age of the new guidelines: considerations based on geography and resources

von Willebrand disease (VWD) is considered the most common bleeding disorder and arises from deficiency and/or defect in the adhesive plasma protein von Willebrand factor (VWF). Diagnosis of VWD requires clinical assessment and is facilitated by laboratory testing. Several guidelines for VWD diagnosis exist, with the latest American Society of Hematology, International Society on Thrombosis and Haemostasis, National Hemophilia Foundation, and World Federation of Hemophilia 2021 guidelines presenting 11 recommendations, some of which have drawn controversy. In the current narrative review, we provide additional context around difficulties in laboratory diagnosis/exclusion/typing of VWD, with a focus on developing countries/resource-poor settings. In particular, there are many variations in assay methodology, and some methods express high assay variability and poor low-level VWF sensitivity that compromises their utility. Although we favor an initial 4-test assay panel, comprising factor (F) VIII coagulant activity, VWF antigen, VWF glycoprotein Ib binding (VWF:GPIbR or VWF:GPIbM favored over VWF Ristocetin cofactor) and VWF collagen binding, we also provide strategies for laboratories only able to incorporate an initial 3-test assay panel, as favored by the latest guidelines, to improve diagnostic accuracy.

An evaluation of von Willebrand factor (recombinant) therapy for adult patients living with severe type 3 von Willebrand disease

INTRODUCTION

Von Willebrand Factor (VWF) containing concentrates have been used for the treatment of von Willebrand Disease (VWD) for many years. Recently, however, a novel recombinant VWF (rVWF or vonicog alpha, VONVENDI [US], VEYVONDI [Europe]) has arrived to the market for the treatment of VWD. Initially, rVWF was approved by the U.S. Food and Drug Administration (FDA) for the on-demand treatment and control of bleeding episodes and for the perioperative management of bleeding for patients with VWD. More recently, however, the FDA has approved rVWF for routine prophylaxis to prevent bleeding episodes for those patients with severe type 3 VWD receiving on-demand therapy.

AREAS COVERED

This review will focus on recent phase III trial results from NCT02973087 regarding the use of long-term routine twice weekly prophylaxis with rVWF for the prevention of bleed events in patients with severe type 3 VWD.

EXPERT OPINION

A novel rVWF concentrate may have greater hemostatic potential over prior plasma-derived VWF concentrates and is now FDA approved for use in routine prophylaxis for patients with severe type 3 VWD in the United States. This greater hemostatic potential may be due to the presence of ultra-large VWF multimers and a more favorable high-molecular-weight multimer pattern compared to prior pdVWF concentrates.

Genetic determinants of enhanced von Willebrand factor clearance from plasma

BACKGROUND

Enhanced von Willebrand factor (VWF) clearance from plasma is associated with von Willebrand disease (VWD). However, the genetic background of this disease mechanism is not well defined.

OBJECTIVE

To determine VWF variants that are associated with reduced VWF survival.

METHODS

Two hundred fifty-four patients with VWD (type 1 = 50 and type 2 = 204) were investigated, and the results were compared with 120 healthy controls. The patients were comprehensively characterized for phenotypic and genetic features. The ratio of VWF propeptide (VWFpp)/VWF antigen (VWFpp ratio) was used to establish in each patient the VWF clearance state.

RESULTS

Out of 92 variants associated with type 1 (7 were novel) and type 2 VWD, 19 had a VWFpp ratio ranging from 1.7 to 2.2, 24 had a VWFpp ratio between 2.3 and 2.9, and 24 variants had a ratio of ≥3. The VWFpp median ratio in healthy controls was 0.98 (0.55-1.6) so that a cut-off value of >1.6 was considered an indicator of accelerated VWF clearance from plasma. An enhanced VWF clearance was observed in 34% of type 1 cases, 100% of type 1 Vicenza cases, 81% of 2A cases, 77% of 2B cases, 88% of 2M cases, and 36% of 2N cases.

CONCLUSIONS

An accelerated VWF clearance was found in most patients with type 2A, 2B, and 2M VWD, with a lower proportion of type 1 and 2N. Sixty-seven different variants alone or in combination with other variants were associated with an increased VWFpp ratio. The variants with the highest VWFpp ratio were mostly located in the D3-A1 VWF domains.

Effects of convalescent plasma infusion on the ADAMTS13-von Willebrand factor axis and endothelial integrity in patients with severe and critical COVID-19

Background

Convalescent plasma infusion (CPI) was given to patients with COVID-19 during the early pandemic with mixed therapeutic efficacy. However, the impacts of CPI on the ADAMTS13-von Willebrand factor (VWF) axis and vascular endothelial functions are not known.

Objectives

To determine the impacts of CPI on the ADAMTS13-VWF axis and vascular endothelial functions.

Methods

Sixty hospitalized patients with COVID-19 were enrolled in the study; 46 received CPI and 14 received no CPI. Plasma ADAMTS13 activity, VWF antigen, endothelial syndecan-1, and soluble thrombomodulin (sTM) were assessed before and 24 hours after treatment.

Results

Patients with severe and critical COVID-19 exhibited significantly lower plasma ADAMTS13 activity than the healthy controls. Conversely, these patients showed a significantly increased VWF antigen. This resulted in markedly reduced ratios of ADAMTS13 to VWF in these patients. The levels of plasma ADAMTS13 activity in each patient remained relatively constant throughout hospitalization. Twenty-four hours following CPI, plasma ADAMTS13 activity increased by ∼12% from the baseline in all patients and ∼21% in those who survived. In contrast, plasma levels of VWF antigen varied significantly over time. Patients who died exhibited a significant reduction of plasma VWF antigen from the baseline 24 hours following CPI, whereas those who survived did not. Furthermore, patients with severe and critical COVID-19 showed significantly elevated plasma levels of syndecan-1 and sTM, similar to those found in patients with immune thrombotic thrombocytopenic purpura. Both syndecan-1 and sTM levels were significantly reduced 24 hours following CPI.

Conclusion

Our results demonstrate the relative deficiency of plasma ADAMTS13 activity and endothelial damage in patients with severe and critical COVID-19, which could be modestly improved following CPI therapy.

An Overview of Laboratory Testing for ADAMTS13

ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) is also called von Willebrand factor (VWF) cleaving protease (VWFCP). ADAMTS13 acts to cleave VWF multimers and thus reduce plasma VWF activity. In the absence of ADAMTS13 (i.e., in thrombotic thrombocytopenia purpura, TTP), plasma VWF can accumulate, in particular as "ultra-large" VWF multimers, and this can lead to thrombosis. Relative deficiencies in ADAMTS13 can also occur in a variety of other conditions, including secondary thrombotic microangiopathies (TMA). Of contemporary interest, COVID-19 (coronavirus disease 2019) may also be associated with relative reduction of ADAMTS13 and also pathological accumulation of VWF, with this likely contributing to the thrombosis risk seen in affected patients. Laboratory testing for ADAMTS13 can assist in the diagnosis of these disorders (i.e., TTP, TMA), as well as in their management, and can be achieved using a variety of assays. This chapter therefore provides an overview of laboratory testing for ADAMTS13 and the value of such testing to assist the diagnosis and management of associated disorders.

Toward gene therapy for congenital thrombotic thrombocytopenic purpura

Congenital thrombotic thrombocytopenic purpura (cTTP) is caused by a severe deficiency in the plasma metalloprotease ADAMTS-13. The current management of cTTP is dependent on the prophylactic administration of ADAMTS-13 via plasma infusion. This is a demanding therapy for patients because transfusions are lifelong and time-consuming and allergic reactions frequently occur. Although current management of cTTP controls acute episodes, it does not provide a long-lasting cure for this disease. The endogenous expression of ADAMTS-13 after gene transfer would provide a curative therapy and ongoing research explores various preclinical gene therapeutic approaches for cTTP. This review focuses on the current state of the literature regarding preclinical gene therapy studies for cTTP and on the challenges of developing a gene therapy medicinal product for cTTP.

Mechanisms of ADAMTS13 regulation

Recombinant ADAMTS13 is currently undergoing clinical trials as a treatment for hereditary thrombotic thrombocytopenic purpura, a lethal microvascular condition resulting from ADAMTS13 deficiency. Preclinical studies have also demonstrated its efficacy in treating arterial thrombosis and inflammation without causing bleeding, suggesting that recombinant ADAMTS13 may have broad applicability as an antithrombotic agent. Despite this progress, we currently do not understand the mechanisms that regulate ADAMTS13 activity in vivo. ADAMTS13 evades canonical means of protease regulation because it is secreted as an active enzyme and has a long half-life in circulation, suggesting that it is not inhibited by natural protease inhibitors. Although shear can spatially and temporally activate von Willebrand factor to capture circulating platelets, it is also required for cleavage by ADAMTS13. Therefore, spatial and temporal regulation of ADAMTS13 activity may be required to stabilize von Willebrand factor-platelet strings at sites of vascular injury. This review outlines potential mechanisms that regulate ADAMTS13 in vivo including shear-dependency, local inactivation, and biochemical and structural regulation of substrate binding. Recently published structural data of ADAMTS13 is discussed, which may help to generate novel hypotheses for future research.

What is the role of Von Willebrand factor in chronic hepatitis B virus infection to hepatocellular carcinoma: a review article

Von Willebrand factor (VWF) is a glycoprotein synthesized and secreted by vascular endothelial cells and megakaryocytes, found on plasma surface, endothelial cells, and α-granule of platelets. VWF can be interacted with collagen and platelet membrane glycoproteins GPIb and GPIb-IIa and play an important role in platelet adhesion and aggregation. Growing research evidence suggests that VWF also mediates the prevention or protesting of hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB) patients from several clinical studies. While the mechanism of VWF in HCC protection or protest is still unclear, further study is required. This article aims to rationalize the role of VWF in the development of HCC, and the functional domain of VWF in cancer as well as cross-talking with platelets and miRNAs. This article also looks forward to the future development and challenges of VWF research.

Clinical significance of substantially elevated von Willebrand factor antigen levels in patients with advanced chronic liver disease

BACKGROUND

Von Willebrand factor antigen (VWF) is a non-invasive marker for clinically significant portal hypertension (HVPG≥10 mmHg) and confers HVPG-independent prognostic information. While quantification of increased VWF-levels is not relevant in the context of von Willebrand disease, highly elevated VWF may be of clinical significance in ACLD. Thus, we have modified our analytical approach to quantify very high VWF-levels (i.e.,>420%) and investigated their prognostic value.

METHODS

Patients undergoing HVPG-measurement at the Vienna Hepatic Hemodynamic Lab with evidence of ACLD and information on VWF were considered. Clinical stages (CS) were defined as follows: Probable compensated ACLD (cACLD): LSM≥10kPa&HVPG<6 mmHg; 0: cACLD&6-9 mmHg; 1: cACLD&HVPG≥10 mmHg; 2: bleeding; 3: non-bleeding decompensation; 4: ≥2 decompensations.

RESULTS

124 (16%) of 793 patients had VWF>420%. The proportion of VWF>420% increased with disease severity (probable cACLD-0: 5(4%) vs. 1: 22(10%) vs. 2-4: 97(23%),p ≤ 0.001) as well as across HVPG (<6mmHg: 1(2%) vs. 6-9: 6(6%) vs. 10-15: 17(9%) vs. ≥16: 100(22%),p ≤ 0.001) and MELD (<10: 17(6%) vs. 10-14: 27(10%) vs. ≥15: 79(32%),p ≤ 0.001) strata. In patients with VWF>420%, median VWF was 533 (IQR:466-611)% and VWF was unrelated to HVPG (Spearman's ρ=0.139,p = 0.123), but showed direct correlations of weak/moderate strength with MELD (ρ=0.336,p < 0.001) and CRP (ρ=0.286,p = 0.001). In the subgroup with VWF>420%, VWF was predictive of decompensation/liver-related mortality (VWF per 10%; hazard ratio (HR): 1.02(95% confidence interval (95%CI): 1.01-1.04),p = 0.008, even after adjusting for other factors (VWF per 10%; adjusted HR: 1.02(95%CI: 1.00-1.05),p = 0.031).

CONCLUSION

The proportion of patients with substantially elevated VWF values steadily increases with disease progression. While VWF is not reflective of HVPG in these patients, it is correlated with hepatic dysfunction and systemic inflammation. Importantly, quantification of high values provides prognostic information.

Von Willebrand Factor Multimer Analysis by Low Resolution SDS-Agarose Gel Electrophoresis

Von Willebrand factor (VWF) is a complex glycoprotein found in plasma, composed of disulfide-bond-linked multimers with apparent molecular weights between 500 kDa and 20,000 kDa. After release of VWF from storage granules, it is cleaved in flowing blood by the specific metalloproteinase ADAMTS13, resulting in a highly characteristic cleavage pattern and structure. As the structure of VWF multimers determines diagnosis of von Willebrand disease, which has different sub-types with different multimer- and cleavage patterns, VWF analysis is performed using low-resolution horizontal SDS-agarose gel electrophoresis. However, almost every laboratory uses a different protocol, and all experimental details are rarely, if at all, described. Therefore, the results from similar methods may be substantially different. Here, we present a detailed description of a validated VWF multimer method that we have developed. It has been successfully used for over more than 20 years in quality control of recombinant and plasma-derived VWF drug products, and in preclinical and clinical studies with VWF drug candidates. As most of the published methods, it enables visualization of VWF multimers separated by electrophoresis by immunostaining with a polyclonal anti-human VWF antibody followed by a secondary antibody coupled to alkaline phosphatase. VWF appears as a series of regularly spaced bands on the low and middle molecular weight range of the gel, with an unresolved zone in the high molecular weight (HMW) range, where ultra-large multimers are found. An example is shown below. This low-resolution agarose gel electrophoresis allows the determination of the number of VWF multimers with high reproducibility. Graphical abstract: Example of electrophoretic analysis of multimer structure of four batches of a recombinant VWF drug substance.

COVID-19 microthrombosis: unusually large VWF multimers are a platform for activation of the alternative complement pathway under cytokine storm

ADAMTS13, a metalloproteinase, specifically cleaves unusually large multimers of von Willebrand factor (VWF), newly released from vascular endothelial cells. The ratio of ADAMTS13 activity to VWF antigen (ADAMTS13/VWF) and indicators of the alternative complement pathway (C3a and sC5b-9) are both related to the severity of COVID-19. The ADAMTS13/VWF ratio is generally moderately decreased (0.18–0.35) in patients with severe COVID-19. When these patients experience cytokine storms, both interleukin-8 and TNFα stimulate VWF release from vascular endothelial cells, while interleukin-6 inhibits both production of ADAMTS13 and its interaction with VWF, resulting in localized severe deficiency of ADAMTS13 activity. Platelet factor 4 and thrombospondin-1, both released upon platelet activation, bind to the VWF-A2 domain and enhance the blockade of ADAMTS13 function. Thus, the released unusually-large VWF multimers remain associated with the vascular endothelial cell surface, via anchoring with syndecan-1 in the glycocalyx. Unfolding of the VWF-A2 domain, which has high sequence homology with complement factor B, allows the domain to bind to activated complement C3b, providing a platform for complement activation of the alternative pathway. The resultant C3a and C5a generate tissue factor-rich neutrophil extracellular traps (NETs), which induce the mixed immunothrombosis, fibrin clots and platelet aggregates typically seen in patients with severe COVID-19.

Residues R1075, D1090, R1095, and C1130 Are Critical in ADAMTS13 TSP8-Spacer Interaction Predicted by Molecular Dynamics Simulation

ADAMTS13 (A Disintegrin and Metalloprotease with Thrombospondin type 1 repeats, member 13) cleaves von Willebrand Factor (VWF) multimers to limit the prothrombotic function of VWF. The deficiency of ADAMTS13 causes a lethal thrombotic microvascular disease, thrombotic thrombocytopenic purpura (TTP). ADAMTS13 circulates in a “closed” conformation with the distal domain associating the Spacer domain to avoid off-target proteolysis or recognition by auto-antibodies. However, the interactions of the distal TSP8 domain and the Spacer domain remain elusive. Here, we constructed the TSP8-Spacer complex by a combination of homology modelling and flexible docking. Molecular dynamics simulation was applied to map the binding sites on the TSP8 or Spacer domain. The results predicted that R1075, D1090, R1095, and C1130 on the TSP8 domain were key residues that interacted with the Spacer domain. R1075 and R1095 bound exosite-4 tightly, D1090 formed multiple hydrogen bonds and salt bridges with exosite-3, and C1130 interacted with both exosite-3 and exosite-4. Specific mutations of exosite-3 (R568K/F592Y/R660K/Y661F/Y665F) or the four key residues (R1075A/D1090A/R1095A/C1130A) impaired the binding of the TSP8 domain to the Spacer domain. These results shed new light on the understanding of the auto-inhibition of ADAMTS13.

2B von Willebrand disease diagnosis: Considerations reflecting on 2021 multisociety guidelines

The recent American Society of Hematology/ISTH/National Hemophilia Foundation/World Federation of Hemophilia 2021 guidelines on the diagnosis of von Willebrand disease (VWD) is an outstanding effort to unify the diagnosis of VWD. However, as mentioned in the guidelines, there are limitations due to the low certainty in the evidence identified for most questions. The panel encouraged critical review of the guidelines. Compared to other subtypes, there is considerable complexity with diagnosis of type 2B VWD, a type that results from a gain-of-function mutation in the VWF gene. Additionally, the discrimination from its phenocopy platelet-type VWD, representing a gain-of-function mutation in the GP1BA gene, is crucial as this determines treatment decisions. In this forum, we highlight the complexities of a type 2B VWD diagnosis; discuss important issues with respect to these complexities: genotype/phenotype/clinical correlations, challenges with platelet aggregation and ristocetin-induced platelet agglutination testing, platelet count, and thrombocytopathy; and, finally, suggest the consideration of some of these complexities in future iterations of the VWD guidelines.

The influence of surface roughness on the damage of von Willebrand Factor under shear flow condition

Despite technological advances in mechanical circulatory support devices to treat end-stage heart failure, blood damage induced by non-physiological shear stress in operation often triggered clinical hemocompatibility complications. The loss of high molecular weight von Willebrand Factor (HMW-VWF) has been considered as an essential cause of gastrointestinal bleeding. In addition to the mechanics factors, interface factors may also affect blood damage, especially the surface characteristics. In this study, the effect of surface roughness on VWF damage under flow condition was investigated. A roller pump circulation experimental platform with a roughness embedded sample chamber was constructed to provide blood shearing flow condition. VWF molecular weight analysis, VWF antigen (VWF-Ag) concentration assay, and VWF ristocetin cofactor activity (VWF-Rico) assay were performed on the sheared blood samples. These variables are the main functional indicators of VWF. It was found that the surface roughness induced VWF damage is mainly caused by the loss of HMW-VWF rather than reducing the total amount of VWF. The threshold value of surface roughness for a rapid increase in the degradation of HMW-VWF under low flow rate was obtained between Ra 0.4 and 0.6 μm, which was smaller than the threshold for hemolysis. Our findings indicated that VWF is more sensitive to the interface factor of surface roughness than red blood cells, thus has a higher requirement for blood pump design. It could provide reference for the material design and processing in developing mechanical circulatory support devices.

Platelet Distribution Width Is Associated with P-Selectin Dependent Platelet Function: Results from the Moli-Family Cohort Study

Defined as an index of platelet size heterogeneity, the platelet distribution width (PDW) is still a poorly characterized marker of platelet function in (sub)clinical disease. We presently validated PDW as a marker of P-selectin dependent platelet activation in the Moli-family cohort. Platelet-bound P-selectin and platelet/leukocyte mixed aggregates were measured by flow cytometry in freshly collected venous blood, both before and after in vitro platelet activation, and coagulation time was assessed in unstimulated and LPS- or TNFα-stimulated whole blood. Closure Times (CT) were measured in a Platelet Function Analyzer (PFA)-100. Multivariable linear mixed effect regression models (with age, sex and platelet count as fixed and family structure as random effect) revealed PDW to be negatively associated with platelet P-selectin, platelet/leukocyte aggregates and von Willebrand factor (VWF), and positively with PFA-100 CT, and LPS- and TNF-α-stimulated coagulation times. With the exception of VWF, all relationships were sex-independent. In contrast, no association was found between mean platelet volume (MPV) and these variables. PDW seems a simple, useful marker of ex vivo and in vitro P-selectin dependent platelet activation. Investigations of larger cohorts will define the usefulness of PDW as a risk predictor of thrombo-inflammatory conditions where activated platelets play a contributing role.

Evaluating errors in the laboratory identification of von Willebrand disease using contemporary von Willebrand factor assays

von Willebrand disease (VWD) arises from deficiency and/or defects of von Willebrand factor (VWF). Assessment requires test panels, including VWF activity and antigen. Appropriate diagnosis including differential identification of qualitative versus quantitative defects remains problematic but has important management implications. Data using a large set (n=27) of varied plasma samples comprising both quantitative VWF deficiency ('Type 1 and 3') vs qualitative defects ('Type 2') tested in a cross-laboratory setting have been evaluated to assess contemporary VWF assays for utility to differentially identify sample types. Different VWF assays and activity/antigen ratios showed different utility in VWD and type identification. Identification errors were linked to assay limitations, including variability, and laboratory issues (e.g., test result misinterpretation). Quantitative deficient (type 1) samples were misinterpreted as qualitative defects (type 2) on 35/467 occasions (7.5% error rate); 11.4% of these errors were due to laboratories misinterpreting their own data, which was instead consistent with quantitative deficiencies. Conversely, qualitative defects were misinterpreted as quantitative deficiencies at a higher error rate (14.3%), but this was more often due to laboratories misinterpreting their data (40% of errors). For test-associated errors, VWF:RCo and VWF:GPIbM were associated with the highest variability and error rate, which was many-fold higher than that using VWF:CB. Chemiluminescence ('CLIA') procedures were associated with lowest inter-laboratory variability and errors overall. These findings in part explain the high rate of errors associated with VWD diagnosis. VWF:GPIbM showed a surprisingly high rate of test associated errors, whilst CLIA procedures performed best overall.

Characterization of the interactions of ADAMTS13 CUB1 domain to WT- and GOF-Spacer domain by molecular dynamics simulation

Metalloprotease ADAMTS13 specifically cleaves VWF (von Willebrand Factor) to prevent excessive platelet aggregation and thrombus formation at the sites of vascular injury. To avoid non-specific cleavage, ADAMTS13 has the auto-inhibition effect in which the Spacer domain in N-terminal interacts with the CUB1 domain in C-terminal, resulting in decreased proteolytic activity. Previous studies reported that exosite-3 in the Spacer domain was a key binding site in the Spacer-CUB1 interaction. When exosite-3 was mutated (R660K/F592Y/R568K/Y661F/Y665F, GOF), the auto-inhibition of ADAMTS13 was disrupted and the enzymatic activity was markedly increased. However, the characteristics of the Spacer-CUB1 interaction is not fully understood. Here, we constructed the model of Spacer-CUB1 complex by homologous modeling and molecular docking to characterize the Spacer-CUB1 binding and predict key amino acid residues via molecular dynamics simulation. Our data showed that G607-S610 was a non-reported potential binding site in the Spacer domain; GOF mutation attenuated the formation of hydrogen bond between exosite-3 and the CUB1 domain; Residues E1231, R1251, L1258, D1259 and T1261 in the CUB1 domain might play an important role in the Spacer-CUB1 interaction. Our study advances the understanding of the structural basis of the auto-inhibition of ADAMTS13 and provides information about the key residues in the binding interface.

The antioxidant N-acetylcysteine promotes immune response and inhibits epithelial-mesenchymal transition to alleviate pulmonary fibrosis in chronic obstructive pulmonary disease by suppressing the VWF/p38 MAPK axis

Background/aim

N-Acetylcysteine (NAC) demonstrates applications in the prevention of exacerbation of chronic obstructive pulmonary disease (COPD). COPD is often characterized by fibrosis of the small airways. This study aims at investigating the physiological mechanisms by which NAC might mediate the pulmonary fibrosis in COPD.

Methods

A total of 10 non-smokers without COPD and 10 smokers with COPD were recruited in this study, and COPD rat models were established. Cigarette smoke extract (CSE) cell models were constructed. The gain- or loss-of-function experiments were adopted to determine the expression of VWF and the extent of p38 MAPK phosphorylation, levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and immunoglobulins (IgG, IgM and IgA) in the serum of COPD rats and supernatant of alveolar epithelial cells and to detect cell invasion and migration and the ratio of CD3⁺, CD4⁺, CD8⁺ and CD4⁺/CD8⁺T lymphocytes.

Results

Expression of VWF and the extent of p38 MAPK phosphorylation were increased in COPD. NAC inhibited p38 MAPK phosphorylation by reducing the VWF expression. NAC could inhibit cell migration and invasion, elevate E-cadherin expression, the ratio of CD3⁺, CD4⁺, CD8⁺ and CD4⁺/CD8⁺T lymphocytes, and levels of IgG, IgA, and IgM, and reduce N-cadherin expression and levels of IL-6 and TNF-α in CSE cells and serum of COPD rats. NAC promoted immune response and suppressed epithelial-mesenchymal transformation (EMT) to relieve COPD-induced pulmonary fibrosis in vitro and in vivo by inhibiting the VWF/p38 MAPK axis.

Conclusions

Collectively, NAC could ameliorate COPD-induced pulmonary fibrosis by promoting immune response and inhibiting EMT process via the VWF/p38 MAPK axis, therefore providing us with a potential therapeutic target for treating COPD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00342-y.

Arf GTPase-activating proteins SMAP1 and AGFG2 regulate the size of Weibel-Palade bodies and exocytosis of von Willebrand factor

Arf GTPase-Activating proteins (ArfGAPs) mediate the hydrolysis of GTP bound to ADP-ribosylation factors (Arfs), which are critical to form transport intermediates. ArfGAPs have been thought to be negative regulators of Arfs; however, accumulating evidence indicates that ArfGAPs are important for cargo sorting and promote membrane traffic. Weibel-Palade bodies (WPBs) are cigar-shaped secretory granules in endothelial cells that contain von Willebrand factor (vWF) as their main cargo. WPB biogenesis at the Golgi was reported to be regulated by Arf and their regulators, but the role of ArfGAPs has been unknown. In this study, we performed siRNA screening of ArfGAPs to investigate the role of ArfGAPs in the biogenesis of WPBs. We found two ArfGAPs, SMAP1 and AGFG2, to be involved in WPB size and vWF exocytosis, respectively. SMAP1 depletion resulted in small-sized WPBs, and the lysosomal inhibitor leupeptin recovered the size of WPBs. The results indicate that SMAP1 functions in preventing the degradation of cigar-shaped WPBs. On the other hand, AGFG2 downregulation resulted in the inhibition of vWF secretion upon Phorbol 12-myristate 13-acetate (PMA) or histamine stimulation, suggesting that AGFG2 plays a role in vWF exocytosis. Our study revealed unexpected roles of ArfGAPs in vWF transport.

Summary: The Arf GTPase-activating proteins SMAP1 and AGFG2 regulate the size of Weibel-Palade bodies and exocytosis of von Willebrand factor.

Identification of VWF as a Novel Biomarker in Lung Adenocarcinoma by Comprehensive Analysis

Lung adenocarcinoma (LUAD) is one of the most malignant tumors with high morbidity and mortality worldwide due to the lack of reliable methods for early diagnosis and effective treatment. It’s imperative to study the mechanism of its development and explore new biomarkers for early detection of LUAD. In this study, the Gene Expression Omnibus (GEO) dataset GSE43458 and The Cancer Genome Atlas (TCGA) were used to explore the differential co-expressed genes between LUAD and normal samples. Three hundred sixity-six co-expressed genes were identified by differential gene expression analysis and Weighted Gene Co-expression Network Analysis (WGCNA) method. Those genes were mainly enriched in ameboidal-type cell migration (biological process), collagen-containing extracellular matrix (cell component), and extracellular matrix structure constituent (molecular function). The protein-protein network (PPI) was constructed and 10 hub genes were identified, including IL6, VWF, CDH5, PECAM1, EDN1, BDNF, CAV1, SPP1, TEK, and SELE. The expression level of hub genes was validated in the GEPIA database, compared with normal tissues, VWF is lowly expressed and SPP1 is upregulated in LUAD tissues. The survival analysis showed increased expression of SPP1 indicated unfavorable prognosis whereas high expression of VWF suggested favorable prognosis in LUAD (p < 0.05). Based on the immune infiltration analysis, the relationship between SPP1 and VWF expression and macrophage, neutrophil, and dendritic cell infiltration was weak in LUAD. Quantitative real-time PCR (qRT-PCR) and western blotting were used to validate the expression of VWF and SPP1 in normal human bronchial epithelial (HBE) cell and three LUAD cell lines, H1299, H1975, and A549. Immunohistochemistry (IHC) was further performed to detect the expression of VWF in 10 cases LUAD samples and matched normal tissues. In summary, the data suggest that VWF is a potential novel biomarker for prognosis of LUAD.

Thrombomodulin is essential for maintaining quiescence in vascular endothelial cells

Thrombomodulin (TM) is a thrombin receptor on endothelial cells that is involved in promoting activation of the anticoagulant protein C pathway during blood coagulation. TM also exerts protective anti-inflammatory properties through a poorly understood mechanism. In this study, we investigated the importance of TM signaling to cellular functions by deleting it from endothelial cells by CRISPR-Cas9 technology and analyzed the resultant phenotype of TM-deficient (TM ^-/- ) cells. Deficiency of TM in endothelial cells resulted in increased basal permeability and hyperpermeability when stimulated by thrombin and TNF-α. The loss of the basal barrier permeability function was accompanied by increased tyrosine phosphorylation of VE-cadherin and reduced polymerization of F-actin filaments at cellular junctions. A significant increase in basal NF-κB signaling and expression of inflammatory cell adhesion molecules was observed in TM ^-/- cells that resulted in enhanced adhesion of leukocytes to TM ^-/- cells in flow chamber experiments. There was also a marked increase in expression, storage, and release of the von Willebrand factor (VWF) and decreased storage and release of angiopoietin-2 in TM ^-/- cells. In a flow chamber assay, isolated platelets adhered to TM ^-/- cells, forming characteristic VWF-platelet strings. Increased VWF levels and inflammatory foci were also observed in the lungs of tamoxifen-treated ERcre-TM^f/f mice. Reexpression of the TM construct in TM ^-/- cells, but not treatment with soluble TM, normalized the cellular phenotype. Based on these results, we postulate cell-bound TM endows a quiescent cellular phenotype by tightly regulating expression of procoagulant, proinflammatory, and angiogenic molecules in vascular endothelial cells.

The role of von Willebrand factor in breast cancer metastasis

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VWF plays an important role in breast tumour progression and metastasis.

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Patients with metastatic breast cancer have significantly elevated plasma VWF.

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Increased levels of highly adhesive VWF may regulate platelet-tumour interactions.

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VWF may protect disseminated tumour cells from chemotherapy.

Breast cancer is the most common female cancer globally, with approximately 12% of patients eventually developing metastatic disease. Critically, limited effective treatment options exist for metastatic breast cancer. Recently, von Willebrand factor (VWF), a haemostatic plasma glycoprotein, has been shown to play an important role in tumour progression and metastasis. In breast cancer, a significant rise in the plasma levels of VWF has been reported in patients with malignant disease compared to benign conditions and healthy controls, with an even greater increase seen in patients with disseminated disease. Direct interactions between VWF, tumour cells, platelets and endothelial cells may promote haematogenous dissemination and thus the formation of metastatic foci. Intriguingly, patients with metastatic disease have unusually large VWF multimers. This observation has been proposed to be a result of a dysfunctional or deficiency of VWF-cleaving protease activity, ADAMTS-13 activity, which may then regulate the platelet-tumour adhesive interactions in the metastatic process. In this review, we provide an overview of VWF in orchestrating the pathological process of breast cancer dissemination, and provide supporting evidence of the role of VWF in mediating metastatic breast cancer.

Von Willebrand factor in aortic or mitral valve stenosis and bleeding after heart valve surgery

OBJECTIVES

Low von Willebrand factor (VWF) increases the risk of bleeding. The objective was to assess the influence of VWF on bleeding after valvular surgery.

METHODS

We studied 82 consecutive patients in median age of 65.5 years with severe isolated aortic stenosis (AS, n = 62) or mitral stenosis (MS, n = 20), undergoing heart valve surgery in extracorporeal circulation. Preoperatively, we assessed VWF antigen (VWF:Ag) and activity (VWF:RCo), a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), and fibrinolysis inhibitors.

RESULTS

Compared with AS, MS patients were more frequently female (80 vs. 55%, p = 0.045) with atrial fibrillation (AF) (80 vs. 8%, p < 0.0001), with no difference in age or comorbidities. Median postoperative drainage was 420 ml for AS, and 425 ml for MS (p = 0.37). Patients with AS had lower VWF:RCo (125.8 [88.5-160.8] vs. 188.0 [140.3-207.3] IU/dl, p = 0.003) and VWF:Ag (135.8 [112.0-171.2] vs. 191.7 [147.3-236.4] IU/dl, p = 0.01) than MS patients. Mean VWF:RCo/Ag ratio was 0.88 ± 0.17, with no intergroup differences. ADAMTS13 levels and activity were similar in both groups. In AS, both VWF:RCo and VWF:Ag correlated inversely with maximal (r = -0.39, p = 0.0003 and r = -0.39, p = 0.0004, respectively) and mean (r = -0.40, p = 0.0004 and r = -0.39, p = 0.0006, respectively) transvalvular pressure gradients. There was no difference in perioperative bleeding between patients following mitral and aortic valve surgery, and bleeding was not associated with VWF:Ag or VWF:RCo.

CONCLUSIONS

In severe AS, VWF levels and activity correlate inversely with transvalvular pressure gradients, and are lower than in severe degenerative MS, but do not affect blood loss after valvular surgery in extracorporeal circulation.

Diverse activities of von Willebrand factor in traumatic brain injury and associated coagulopathy

Traumatic brain injury (TBI) is a leading cause of death and disability. Patients with isolated TBI lose a limited amount of blood to primary injury, but they often develop secondary coagulopathy, resulting in delayed or recurrent intracranial and intracerebral hematoma. TBI-induced coagulopathy is closely associated with poor outcomes for these patients, including death. This secondary coagulopathy is consumptive in nature, involving not only brain-derived molecules, coagulation factors, and platelets, but also endothelial cells in a complex process now called blood failture. A key question is how a localized injury to the brain is rapidly disseminated to affect systemic hemostasis that is not directly affected the way it is in trauma to the body and limbs, especially with hemorrhagic shock. Increasing evidence suggests that the adhesive ligand von Willebrand factor (VWF), which is synthesized in and released from endothelial cells, plays a paradoxical role in both facilitating local hemostasis at the site of injury and also propagating TBI-induced endotheliopathy and coagulopathy systemically. This review discusses recent progress in understanding these diverse activities of VWF and the knowledge gaps in defining their roles in TBI and associated coagulopathy.

How we diagnose 2M von Willebrand disease (VWD): Use of a strategic algorithmic approach to distinguish 2M VWD from other VWD types

INTRODUCTION

von Willebrand disease (VWD) is the most common inherited bleeding disorder and caused by an absence, deficiency or defect in von Willebrand factor (VWF). VWD is currently classified into six different types: 1, 2A, 2B, 2N, 2M, 3. Notably, 2M VWD is more often misdiagnosed as 2A or type 1 VWD than properly identified as 2M VWD.

AIM

To describe an algorithmic approach to better ensure appropriate identification of 2M VWD, and reduce its misdiagnosis, as supported by sequential laboratory testing.

METHODS

Comparative assessment of types 1, 2A, 2B and 2M VWD using various laboratory tests, including VWF antigen and several VWF activity assays, plus DDAVP challenge data, ristocetin-induced platelet agglutination (RIPA) data, multimer analysis and genetic testing.

RESULTS

Types 1, 2A, 2B and 2M VWD give characteristic test patterns that can provisionally classify patients into particular VWD types. Notably, type 1 VWD shows low levels of VWF, but VWF functional concordance (VWF activity/Ag ratios >0.6), with both baseline assessment and post-DDAVP. Types 2A, 2B and 2M VWD show VWF functional discordance (low VWF activity/Ag ratio(s)) dependent on the defect, but type 2M separates from 2A/2B VWD based on specific test patterns, especially with collagen binding vs glycoprotein Ib binding assays. RIPA identifies 2B VWD. Multimers separate 2M from 2A/2B.

CONCLUSION

We provide strategies to improve correct diagnosis of VWD, especially focussed on 2M VWD, and which can be used by most diagnostic haemostasis laboratories, reserving genetic analysis (if required) for confirmation.

VAMP3 and SNAP23 as Potential Targets for Preventing the Disturbed Flow-Accelerated Thrombus Formation

Disturbed blood flow has been recognized to promote platelet aggregation and thrombosis via increasing accumulation of von Willebrand factor (VWF) at the arterial post-stenotic sites. The mechanism underlying the disturbed-flow regulated endothelial VWF production remains elusive. Here we described a mouse model, in which the left external carotid artery (LECA) is ligated to generate disturbed flow in the common carotid artery. Ligation of LECA increased VWF accumulation in the plasma. Carotid arterial thrombosis was induced by ferric chloride (FeCl₃) application and the time to occlusion in the ligated vessels was reduced in comparison with the unligated vessels. In vitro, endothelial cells were subjected to oscillatory shear (OS, 0.5 ± 4 dynes/cm²) or pulsatile shear (PS, 12 ± 4 dynes/cm²). OS promoted VWF secretion as well as the cell conditioned media-induced platelet aggregation by regulating the intracellular localization of vesicle-associated membrane protein 3 (VAMP3) and synaptosomal-associated protein 23 (SNAP23). Disruption of vimentin intermediate filaments abolished the OS-induced translocation of SNAP23 to the cell membrane. Knockdown of VAMP3 and SNAP23 reduced the endothelial secretion of VWF. Systemic inhibition of VAMP3 and SNAP23 by treatment of mice with rapamycin significantly ameliorated the FeCl₃-induced thrombogenesis, whereas intraluminal overexpression of VAMP3 and SNAP23 aggravated it. Our findings demonstrate VAMP3 and SNAP23 as potential targets for preventing the disturbed flow-accelerated thrombus formation.

von Willebrand factor promotes platelet-induced metastasis of osteosarcoma through activation of the VWF-GPIb axis

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Immunohistochemistry results directly show VWF is increased during tumor progression.

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VWF is expressed as low molecular weight multimer in OS cell line SAOS2.

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VWF promotes platelet-induced metastasis of OS through VWF-GPIb pathway.

von Willebrand factor (VWF) is exclusively expressed in endothelial cells (ECs) and megakaryocytes, which plays a crucial role in the initiation of arterial thrombosis. Recent studies have shown that VWF is also expressed in osteosarcoma (OS) cells and participates in adhesion of cancer cells to platelets, thus promoting metastasis of OS cells. However, it is unclear how OS cell-derived VWF-platelet interaction contributes to the metastasis of OS. We hypothesized that the interaction is mediated by the binding between VWF A1 and GPIbα of platelets, a molecular mechanism similar to that of thrombosis. The increased expression of VWF in SAOS2 cells may contribute to the enhancement of platelet adhesion through the VWF-GPIb pathway, which could promote the migration and invasion capacities of SAOS2 cells in vitro. Antibodies that block the pathway could significantly inhibit the platelet-induced metastasis of OS cells. Our results suggest a theoretical basis for the development of new anti-OS metastasis drugs, and further enrich the mechanism of OS metastasis.

ADAMTS13 activity is associated with early neurological improvement in acute ischemic stroke patients treated with intravenous thrombolysis

Although intravenous thrombolysis (IVT) with recombinant tissue-plasminogen-activator represents a highly effective treatment in acute ischemic stroke patients, not every patient benefits. We hypothesized that pretreatment levels of mediators of hemostasis (VWF and ADAMTS13) and dimethylarginines (ADMA and SDMA) are associated with early neurological improvement and outcome after IVT in ischemic stroke. Moreover we aimed to investigate the link between ADAMTS13 and markers of inflammation (CRP, IL-6, MMP-9 and MCP-1). In 43 patients with acute ischemic stroke treated with IVT blood samples for determination of the different markers were strictly taken before treatment, as well as at 24 h, 3, 7 and 90 days after symptom onset. Early neurological improvement was assessed using the shift between National Institutes of Health Stroke Scale (NIHSS) at baseline and at 24 h. Outcome at 90 days was assessed using the modified Rankin Scale. The lowest quartile of ADAMTS13 activity was independently associated with less improvement in NIHSS (baseline-24 h) (OR 1.298, p = 0.050). No independent association of ADMA or SDMA levels at baseline with outcome could be shown. Furthermore, IL-6, MCP-1 and CRP levels at 90 days significantly differed between patients with low and high ADAMTS13 activity. Thus, ADAMTS13 might indicate or even influence efficacy of IVT.

Von Willebrand Factor and ADAMTS13 and long-term outcomes in patients undergoing percutaneous coronary intervention

BACKGROUND

Von Willebrand factor (VWF) and its cleaving protease a disintegrin-like and metalloprotease with thrombospondin type I repeats 13 (ADAMTS13) are pivotal mediators of thrombosis and are associated with the progression of atherosclerosis. We investigated the impact of VWF, ADAMTS13 and VWF/ADAMTS13 on long-term major adverse cardiovascular outcomes (MACE) in patients undergoing percutaneous coronary intervention (PCI).

METHODS

We analysed 701 patients undergoing PCI between 2003 and 2006. VWF and ADAMTS13 antigen levels were measured before PCI. As primary endpoint, we investigated MACE, a composite of all-cause mortality, myocardial infarction or ischemic stroke during 8 years of follow-up. As secondary endpoint, we investigated all-cause mortality.

RESULTS

Mean age was 63.8 years, 496 (70.8%) were male. Acute coronary syndrome (ACS) was diagnosed in 347 (49.5%) patients, stable coronary artery disease (SCAD) in 354 (50.5%). During follow-up 228 (32.5%) patients experienced MACE, and 161 (23.0%) died. In ACS patients, VWF was significantly associated with MACE (HR 1.402 (95%CI 1.003-1.959), p = 0.048), whereas ADAMTS13 and VWF/ADAMTS13 had no predictive value. In SCAD, neither VWF, ADAMTS13, nor VWF/ADAMTS13 correlated with MACE. VWF was significantly associated with all-cause death in ACS patients (HR 1.841 (95%CI 1.187-2.856), p = 0.006), but not in SCAD (1.394 (95%CI 0.856-2.269), p = 0.181). ADAMTS13 and VWF/ADAMTS13 were not correlated with ACS and SCAD, respectively.

CONCLUSION

VWF but not ADAMTS13 and VWF/ADAMTS13 was associated with MACE and mortality in patients with ACS but not SCAD. This finding highlights the importance of VWF as an essential marker of risk in patients with ACS.

Activated αIIbβ3 on platelets mediates flow-dependent NETosis via SLC44A2

Platelet-neutrophil interactions are important for innate immunity, but also contribute to the pathogenesis of deep vein thrombosis, myocardial infarction and stroke. Here we report that, under flow, von Willebrand factor/glycoprotein Ibα-dependent platelet 'priming' induces integrin αIIbβ3 activation that, in turn, mediates neutrophil and T-cell binding. Binding of platelet αIIbβ3 to SLC44A2 on neutrophils leads to mechanosensitive-dependent production of highly prothrombotic neutrophil extracellular traps. A polymorphism in SLC44A2 (rs2288904-A) present in 22% of the population causes an R154Q substitution in an extracellular loop of SLC44A2 that is protective against venous thrombosis results in severely impaired binding to both activated αIIbβ3 and VWF-primed platelets. This was confirmed using neutrophils homozygous for the SLC44A2 R154Q polymorphism. Taken together, these data reveal a previously unreported mode of platelet-neutrophil crosstalk, mechanosensitive NET production, and provide mechanistic insight into the protective effect of the SLC44A2 rs2288904-A polymorphism in venous thrombosis.

Laboratory monitoring during pregnancy and post-partum hemorrhage in women with von Willebrand disease

BACKGROUND

Evidence-based guidelines recommend that von Willebrand factor (VWF) levels be obtained in the third trimester of pregnancy to facilitate peripartum planning for women with von Willebrand disease (VWD).

OBJECTIVES

To identify the frequency of third trimester monitoring in a nationally representative sample of pregnant women with VWD in the United States, as well as the frequency of reproductive bleeding after pregnancy.

PATIENTS/METHODS

Patient data were obtained from the Truven Health MarketScan Research Databases. International Classification of Diseases-9 codes were used to identify women with VWD and evidence of infant delivery. We defined third trimester monitoring as a laboratory claim for VWF levels during the 3 months before delivery. Clinical outcomes studied included postpartum hemorrhage (PPH) and heavy menstrual bleeding (HMB).

RESULTS

We identified 2238 unique pregnant females with VWD. Of these, 32% (n = 714) underwent third-trimester testing of VWF levels. Diagnostic codes consistent with PPH were recorded for 6.5% of women in the 6 weeks after infant delivery. The frequency of PPH in women who underwent VWF monitoring (4.9%) was significantly lower than in those who did not undergo monitoring (7.3%), (risk difference -2.4%, 95% CI -4.4% to -0.3%, P = .023). Diagnostic codes consistent with HMB were recorded for 4.7% of women in the 3 months after infant delivery.

CONCLUSIONS

Third-trimester VWF monitoring was associated with a lower risk of PPH, but testing was performed in only one-third of insured pregnant women with VWD in the United States despite expert recommendations.

ADAMTS13 ameliorates inflammatory responses in experimental autoimmune encephalomyelitis

BACKGROUND

ADAMTS13 (a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13) plays a vital role in preventing microvascular thrombosis and inflammation. Reduced ADAMTS13 levels in plasma have been detected in multiple sclerosis (MS) patients. In the present study, we have determined the role of ADAMTS13 in the disease progression of MS using a mouse model of experimental autoimmune encephalomyelitis (EAE).

METHODS

Female C57BL/6 mice were immunized with MOG_35-55 peptide and then treated with ADAMTS13 or vehicle in preventive and therapeutic settings. Mice were analyzed for clinical deficit, white matter demyelination and inflammatory cell infiltration. To explore the underlying mechanism, VWF expression and blood-spinal cord barriers (BSCB) were determined.

RESULTS

Plasma ADAMTS13 activity was suppressed in EAE mice. ADAMTS13-treated EAE mice exhibited an ameliorated disease course, reduced demyelination, and decreased T lymphocyte, neutrophil and monocyte infiltration into the spinal cord. Consistently, ADAMTS13 treatment reduced VWF levels and inhibited BSCB breakdown in the spinal cords of EAE mice. However, leukocytes in the blood and spleen of EAE mice remained unaffected by ADAMTS13 administration.

CONCLUSION

Our results demonstrate that ADAMTS13 treatment ameliorates inflammatory responses, demyelination and disease course in EAE mice. Therefore, our study suggests that ADAMTS13 may represent a potential therapeutic strategy for MS patients.

Utility of the platelet function analyser (PFA-100/200) for exclusion or detection of von Willebrand disease: A study 22 years in the making

INTRODUCTION

von Willebrand disease (VWD) is the most common inherited bleeding disorder and may alternatively arise as an acquired condition (AVWS). These represent deficiency and/or defects in von Willebrand factor (VWF). Closure times (CTs) obtained from the platelet function analyser (PFA) are highly sensitive to both VWD/AVWS. The current study has evaluated the utility of the PFA-100/-200 to exclude or detect laboratory identified VWD.

MATERIALS AND METHODS

An evaluation of the success or otherwise of prospective PFA testing to help exclude or detect VWD using data from a locally maintained database. This database contains patient information, results of PFA testing, results of VWF testing, platelet count and hematocrit, and additional information, for a current total of 3678 entries representing over 2 decades of testing.

RESULTS

According to selection criteria, a total of 142 samples were identified as derived from patients with VWD. All but one of these were also identified to have abnormal PFA CTs. Additional data sets of patients with 'low VWF' (n = 137), or borderline normal VWF (n = 163) were also identified, as well as patients with thrombocytopenia and/or low hematocrit (n = 487). In these cohorts, PFA CTs were often (but not always) abnormal. There was a strong association between VWF test parameter values and PFA CTs. Additional study samples comprised cases with normal VWF parameters but prolonged CTs (n = 594), as well as cases with normal VWF and normal CTs (n = 1292), permitting calculation of sensitivity of abnormal PFA for VWD (99.3%), as well as specificity (68.5%), negative predictive value (99.9%) and positive predictive value (19.2%), for a prevalence of 7.0%. Comparatively, normal PFA CTs were better able to exclude VWD than normal test results for individual VWF parameters.

CONCLUSION

This study reports on an evaluation of PFA CTs for identification or exclusion of VWD. In our dataset, representing over 22 years of experience, normal PFA CTs were able to predict absence of VWD with higher sensitivity than individual VWF test results.

Release of endothelial activation markers in lungs of patients with malaria-associated acute respiratory distress syndrome

Background

Malaria-associated acute respiratory distress syndrome (MA-ARDS) is an understudied complication of malaria and is characterized by pulmonary inflammation and disruption of the alveolar-capillary membrane. Its pathogenesis remains poorly understood. Since endothelial activation plays an important role in other malarial complications, the expression of two endothelial activation markers, von Willebrand factor (VWF) and angiopoietin-2 (ANG-2), was investigated in the lungs of patients with MA-ARDS.

Methods

Post-mortem lung sections of Plasmodium falciparum-infected patients without alveolar oedema (NA), P. falciparum-infected patients with alveolar oedema (MA-ARDS), and uninfected people who died accidentally with no pathological changes to the lungs (CON) were immunohistochemically stained for VWF and ANG-2, and were evaluated with semi-quantitative analysis.

Results

Alveolar oedematous VWF and ANG-2 and intravascular VWF staining were significantly increased in patients with MA-ARDS versus infected and uninfected control groups. The levels of VWF in the alveolar septa and endothelial lining of large blood vessels of patients with MA-ARDS was significantly decreased compared to controls. ANG-2 expression was increased in the alveolar septa of malaria patients without alveolar oedema versus control patients, while ANG-2⁺ leukocytes were increased in the alveoli in both infected patient groups.

Conclusions

This study documents a high level of VWF and ANG-2, two endothelial activation markers in the oedematous alveoli of post-mortem lung sections of Thai patients with MA-ARDS. Decreased detection of VWF in the endothelial lining of blood vessels, in parallel with an increased presence of intravascular VWF staining suggests marked endothelial activation and Weibel–Palade body release in the lungs of patients with MA-ARDS.

Two cases of von Willebrand disease type 3 in consanguineous Chinese families

BACKGROUND

von Willebrand disease (VWD) is the most common inherited bleeding disorder caused by defective or deficient von Willebrand factor (VWF). VWD type 3 is inherited in autosomal recessive manner. We described clinical and molecular features of VWD type 3 in two consanguineous marriage families.

METHODS

Peripheral blood was collected, PT, APTT, FVIII:C, VWF:RCo, VWF:Ag were measured. A targeted next-generation sequencing panel covering F8, F9, and VWF genes was applied followed by Sanger sequencing.

RESULTS

Both families had a baby die in their first year due to bleeding disorders. A 23-year-old female patient from family A suffered menorrhagia, and another 30-year-old male patient from family B was characterized with hematoma in the lower extremity. Both patients showed severely decreased FVIII:C, VWF:Ag. Recurrent homozygous VWF c.4696C>T (p.Arg1566Ter) nonsense mutation was identified in the female patient, and novel homozygous VWF c.6450C>A (p.Cys2150Ter) nonsense mutation was identified the male patient. Heterozygotes in family members showed mild/moderate decrease in VWF:Ag or VWF:RCo.

CONCLUSIONS

We identified VWD type 3 in two consanguineous marriage families, and our work further strengthen the risk of delivering disorders inherited in AR manner in populations with frequent consanguineous partnerships.

Temporal map of the pig polytrauma plasma proteome with fluid resuscitation and intravenous vitamin C treatment

BACKGROUND

Fluid resuscitation plays a prominent role in stabilizing trauma patients with hemorrhagic shock yet there remains uncertainty with regard to optimal administration time, volume, and fluid composition (e.g., whole blood, component, colloids) leading to complications such as trauma-induced coagulopathies (TIC), acidosis, and poor oxygen transport. Synthetic fluids in combination with antioxidants (e.g., vitamin C) may resolve some of these problems.

OBJECTIVES

We applied quantitative mass spectrometry-based proteomics [liquid chromatography-mass spectrometry (LC-MS/MS)] to map the effects of fluid resuscitation and intravenous vitamin C (VitC) in a pig model of polytrauma (hemorrhagic shock, tissue injury, liver reperfusion, hypothermia, and comminuted bone fracture). The goal was to determine the effects of VitC on plasma protein expression, with respect to changes associated with coagulation and trauma-induced coagulopathy (TIC).

METHODS

Longitudinal blood samples were drawn from nine male Sinclair pigs at baseline, 2 h post trauma, and 0.25, 2, and 4 h post fluid resuscitation with 500 mL hydroxyethyl starch. Pigs were treated intravenously (N = 3/treatment group) with saline, 50 mg VitC/kg (Lo-VitC), or 200 mg VitC/kg (Hi-VitC) during fluid resuscitation.

RESULTS

A total of 436 plasma proteins were quantified of which 136 changed following trauma and resuscitation; 34 were associated with coagulation, complement cascade, and glycolysis. Unexpectedly, Lo-VitC and Hi-VitC treatments stabilized ADAMTS13 levels by ~4-fold (P = .056) relative to saline and enhanced ADAMTS13/von Willebrand factor (VWF) cleavage efficiency based on LC-MS/MS evidence for the semitryptic VWF cleavage product (VWF1275-1286 ).

CONCLUSIONS

This study provides the first comprehensive map of trauma-induced changes to the plasma proteome, especially with respect to proteins driving the development of TIC.

VWF/ADAMTS13 ratio as a potential biomarker for early detection of hepatocellular carcinoma

Background

To investigate the von Willebrand factor to ADAMTS13 ratio as a potential biomarker for early detection of hepatocellular carcinoma (HCC) in cirrhosis.

Methods

Serum levels of alpha-fetoprotein, des-γ-carboxy prothrombin, Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (alpha-fetoprotein-L3%), vascular endothelial growth factor, and vascular endothelial growth factor receptor-2, as well as the plasma levels of von Willebrand factor antigen (von Willebrand factor: Ag) and ADAMTS13 activity (ADAMTS13:AC), were evaluated in 41 cirrhotic patients with HCC undergoing radiofrequency ablation and in 20 cirrhotic patients without HCC. The diagnostic accuracy of each biomarker was evaluated using the receiver operating characteristic curve analysis.

Results

The von Willebrand factor: Ag and von Willebrand factor: Ag/ADAMTS13:AC ratios were significantly higher in cirrhotic patients with HCC than in those without HCC (p < 0.05 and p < 0.01, respectively), whereas ADAMTS13:AC was significantly lower in those with HCC than those without HCC (p < 0.05). However, no relationship was observed between the von Willebrand factor: Ag/ADAMTS13:AC ratio and serum tumor markers such as alpha-fetoprotein, des-γ-carboxy prothrombin, and alpha-fetoprotein-L3%. Multivariate regression analysis identified von Willebrand factor: Ag/ADAMTS13:AC ratio and alpha-fetoprotein-L3% as significant factors of HCC development. Receiver operating characteristic analysis showed that the von Willebrand factor: Ag/ADAMTS13:AC ratio and alpha-fetoprotein-L3% had a better performance than alpha-fetoprotein, des-γ-carboxy prothrombin, alpha-fetoprotein-L3%, vascular endothelial growth factor, and vascular endothelial growth factor receptor-2, von Willebrand factor: Ag, and ADAMTS13:AC. The von Willebrand factor: Ag/ADAMTS13:AC ratio was exclusively correlated with tumor volume and stage as well as serum vascular endothelial growth factor levels.

Conclusions

The von Willebrand factor: Ag/ADAMTS13:AC ratio can potentially serve as a novel biomarker for early diagnosis of HCC in cirrhotic patients.

Shear-Dependent Platelet Aggregation: Mechanisms and Therapeutic Opportunities

Cardiovascular diseases (CVD) are the number one cause of morbidity and death worldwide. As estimated by the WHO, the global death rate from CVD is 31% wherein, a staggering 85% results from stroke and myocardial infarction. Platelets, one of the key components of thrombi, have been well-investigated over decades for their pivotal role in thrombus development in healthy as well as diseased blood vessels. In hemostasis, when a vascular injury occurs, circulating platelets are arrested at the site of damage, where they are activated and aggregate to form hemostatic thrombi, thus preventing further bleeding. However, in thrombosis, pathological activation of platelets occurs, leading to uncontrolled growth of a thrombus, which in turn can occlude the blood vessel or embolize, causing downstream ischemic events. The molecular processes causing pathological thrombus development are in large similar to the processes controlling physiological thrombus formation. The biggest challenge of anti-thrombotics and anti-platelet therapeutics has been to decouple the pathological platelet response from the physiological one. Currently, marketed anti-platelet drugs are associated with major bleeding complications for this exact reason; they are not effective in targeting pathological thrombi without interfering with normal hemostasis. Recent studies have emphasized the importance of shear forces generated from blood flow, that primarily drive platelet activation and aggregation in thrombosis. Local shear stresses in obstructed blood vessels can be higher by up to two orders of magnitude as compared to healthy vessels. Leveraging abnormal shear forces in the thrombus microenvironment may allow to differentiate between thrombosis and hemostasis and develop shear-selective anti-platelet therapies. In this review, we discuss the influence of shear forces on thrombosis and the underlying mechanisms of shear-induced platelet activation. Later, we summarize the therapeutic approaches to target shear-sensitive platelet activation and pathological thrombus growth, with a particular focus on the shear-sensitive protein von Willebrand Factor (VWF). Inhibition of shear-specific platelet aggregation and targeted drug delivery may prove to be much safer and efficacious approaches over current state-of-the-art antithrombotic drugs in the treatment of cardiovascular diseases.

ADAMTS13: An Emerging Target in Stroke Therapy

Thrombosis is the predominant underlying mechanism of acute ischemic stroke (AIS). Though thrombolysis with tPA has been proven to be effective in treating AIS within the time window, the majority of AIS patients fail to receive tPA due to various reasons. Current medical therapies for AIS have limited efficacy and pose a risk of intracerebral hemorrhage. ADAMTS13 (a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13) is a metalloprotease that effectively breaks down the von Willebrand Factor (VWF), a key factor in thrombus formation. Previous studies have proven that dysfunction of ADAMTS13 is associated with many diseases. Recently, ADAMTS13 has been reported to be closely related to stroke. In this review, we briefly described the structure of ADAMTS13 and its role in thrombosis, inflammation, as well as angiogenesis. We then focused on the relationship between ADAMTS13 and AIS, ranging from ischemic stroke occurrence, to AIS treatment and prognosis. Based on research findings from in vitro, animal, and clinical studies, we propose that ADAMTS13 is a potential biomarker to guide appropriate treatment for ischemic stroke and a promising therapeutic agent for tPA resistant thrombi.

Association study of genetic variations of inflammatory biomarkers with susceptibility and severity of obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) increases health risks of cardiovascular disease and stroke. Both genetic factors and environmental exposures contribute to the occurrence of OSA. The purpose of this study was to determine the role of four functional inflammatory single nucleotide polymorphisms (SNPs) (VWF rs1063856, IL-6 rs1800796, TNF rs1800629, and CRP rs2794521) in the susceptibility and severity of OSA.

METHODS

A case-control study of OSA among Chinese population was conducted. Genotyping was performed using ABI TaqMan SNP genotyping technique.

RESULTS

We found VWF rs1063856 (OR = 1.50, 95% CIs = 1.10-2.04; p = 0.010), IL-6 rs1800796 (OR = 1.32, 95% CIs = 1.11-1.56; p = 0.002), TNF rs1800629 (OR = 1.44, 95% CIs = 1.13-1.83; p = 0.003), and CRP rs2794521 (OR = 1.27, 95% CIs = 1.04-1.55; p = 0.021) were all significantly associated with increased susceptibility of OSA, while VWF rs1063856 (OR = 1.75, 95% CIs = 1.18-2.62; p = 0.006), IL-6 rs1800796 (OR = 1.39, 95% CIs = 1.10-1.76; p = 0.006) were associated with the severity of OSA.

CONCLUSIONS

Our study indicated that functional variants of inflammatory biomarkers could cause the occurrence of OSA and influence the severity of OSA. These findings further support that inflammatory cytokines were closely related to the occurrence and development of OSA.

In silico identification of mimicking molecule(s) triggering von Willebrand factor in human: a molecular drug target for regulating coagulation pathway

Blood coagulation is a complex and dynamic process wherein the body activates its emergency mechanism to stop bleeding and wound healing via the interactions of prothrombotic and antithrombotic agents. von Willebrand factor (VWF) is a complex glycoprotein and initial component of the hemostasis pathway which serves a multipurpose role in blood coagulation process. There are reports of various plants that contain several bioactive compounds possessing properties of inducing blood coagulation directly or indirectly. In the present study, efforts have been made to identify bioactive compounds that may play a significant role in regulation of the coagulation cascade by accelerating VWF and thus enhance the hemostasis process. An antidiuretic peptide drug, Desmopressin, works on VWF and releases them in circulation. Forty-seven compounds from different plant sources were screened through molecular docking, out of which two compounds, Emodin and Peruvianoside II, showed more binding affinity than the reference drug Desmopressin. Emodin and Peruvianoside II showed binding energies -7.2 and -7.0 kcal/mol, respectively, when docked with VWF, whereas Desmopressin displayed less binding energy (-6.9 kcal/mol). Emodin belongs to anthraquinone from Rumex hastasus and Peruvianoside II belongs to flavanone glycosides from Thevetia peruviana. The mimicking potential of top identified molecules with respect to the drug was confirmed through simulation analysis. Besides, the molecular dynamics simulation (MDS) study (for 20 ns) showed that the Peruvianoside II protein complex was energetically more stable than Emodin protein complex. Based on the results, Peruvianoside II possesses great potential and thus may be considered for development of drugs for hemostasis.

Pure ultra-fine carbon particles do not exert pro-coagulation and inflammatory effects on microvascular endothelial cells

Pro-thrombotic and inflammatory changes play an important role in cardiovascular morbidity and mortality, resulting from short-term exposure to fine particulate air-pollution. Part of those effects has been attributed to the ultra-fine particles (UFPs) that pass through the lung and directly contact blood-exposed and circulating cells. Despite UFP-induced platelet activation, it is unclear whether the penetrated particles exert any direct effect on endothelial cells. While exposure levels are boosting as a result of world-wide increases in economic development and desertification, which create more air-polluted regions, as well as increase in demands for synthetic UFPs in medicine and various industries, further studies on the health effects of these particles are required. In this study, human pulmonary and cardiac microvascular endothelial cells (MECs) have been exposed to 0.1, 1, 10, and 100 μg/ml suspensions of either a natural (carbon black) or a synthetic (multi-walled carbon nano-tubes) type of UFPs, in vitro. As a result, no changes in the levels of coagulation factor VIII, Von Willebrand factor, Interleukin 8, and P-selectin measured in the cells' supernatant were observed prior to and 6, 12, and 24 h after exposure. In parallel, the spatio-temporal effect of UFPs on cardiac MECs was evaluated by Transmission Electron Microscopy. Despite phagocytic uptake of pure UFPs observed on cellular sections of the treated cells, Weibel-Palade bodies remained intact in shape and similar in number when compared with the untreated cells. Our work shows that carbon itself is a non-toxic carrier for endothelial cells.

ADAMTS-13 activity reduction in plasma of acute myeloid leukemia predicts poor prognosis after bone marrow transplantation

OBJECTIVE

This research aimed to explore the significance of low activity of ADAMTS-13 in acute myeloid leukemia (AML) after bone morrow transplantation (BMT), and to evaluate the disease progress and prognosis of the patients with low or normal activity of ADAMTS-13 after BMT.

METHODS

46 AML patients were included in our research. ADAMTS-13 activity was measured before BMT. Their medical indicators were recorded one month after BMT. All the patients were followed up and their disease progression was evaluated afterwards. The medical indicators and prognosis situation were compared between Low ADAMTS13 Group (<481 ng/ml) and Normal Group (481-785 ng/ml) according to the reference range of local laboratory. ROC curves were used to evaluate the predictive value of ADAMTS13 for infection complications and survival.

RESULTS

Low ADAMTS13 Group show extended APTT, PT and elevated CRP and D-Dimer levels, compared with Normal Group. Low ADAMTS13 Group suffered more BMT-related complications than Normal Group. In addition, Low ADAMTS13 Group underwent higher mortality than Normal Group in the one-year follow up after BMT and two-year follow up after onset of AML. ADAMTS13 has AUC of 0.7675, 0.7254, 0.8019 for lung infection, CMV infection and death within one year after BMT, suggesting that ADAMTS13 has predictive value for prognosis of AML patients after BMT.

DISCUSSION

For patients with low ADAMTS13 activity, the prognosis was worse and the probability of serious complications and mortality was significantly higher than AML patients with normal ADAMTS13 activity, which suggest predictive role of ADAMTS13 activity for the prognosis of AML after BMT.

CONCLUSION

AML patients with low activity of ADAMTS-13 had worse prognosis after BMT.

Significance and Prognostic Value of The Coagulation Profile in Patients with Glioblastoma: Implications for Personalized Therapy

BACKGROUND

Coagulation is an important aspect of the vascular microenvironment in which brain tumors evolve. Patients with tumor often show aberrant coagulation and fibrinolysis activation. In particular, glioblastoma (GBM), the most aggressive primary brain tumor, is associated with a state of hypercoagulability, and venous thromboembolism is a common complication of this cancer and its treatment. Our study aims to investigate the clinical and prognostic significance of routine laboratory tests to assess the coagulative state of patients with brain tumors, to identify potential new prognostic factors and targets for personalized therapy.

METHODS

Blood samples were collected from patients with GBM (n = 58) and patients with meningioma (MNG, n = 22), before any treatment. The parameters analyzed were prothrombin time (PT), activated partial thromboplastin time (aPTT), D dimer (DD), fibrinogen, von Willebrand factor (VWF), leukocyte count, and hemoglobin levels.

RESULTS

Plasma levels of PT and aPTT were significantly reduced in GBMs compared with MNGs (P < 0.05), whereas DD, VWF:Ag levels, and leukocyte count were significantly higher in GBMs than in MNGs (P < 0.01). Furthermore, we observed that patients with GBM with reduced PT and aPTT and high levels of DD and VWF, defined as hypercoagulable patients, showed reduced overall survival (P < 0.05) compared with nonhypercoagulable patients.

CONCLUSIONS

Our data support the assumption that patients with GBM show a plasma hypercoagulable profile and that coagulation profile is related to adverse outcome in patients with GBM. If confirmed, hypercoagulability could play an important role as a prognostic factor of the disease and in the decision of an antithrombotic prophylaxis.