von Willebrand factor: more than a regulator of hemostasis and thrombosis

Procoagulant phenotype of virus-infected pericytes is associated with portal thrombosis and intrapulmonary vascular dilations in fatal COVID-19

BACKGROUND & AIMS

Mechanisms and clinical impact of portal microthrombosis featuring severe COVID-19 are unknown. Intrapulmonary vascular dilation (IPVD)-related hypoxia has been described in severe liver diseases. We hypothesized that portal microthrombosis is associated with IPVD and fatal respiratory failure in COVID-19.

METHODS

Ninety-three patients who died from COVID-19, were analysed for portal microvascular damage (histology), IPVD (histology and chest-computed tomography, CT), and hypoxemia (arterial blood gas). Seventeen patients who died from COVID-19-unrelated pneumonia served as controls. Vascular lesions and microthrombi were phenotyped for endothelial (vWF) and pericyte (αSMA/PDGFR-β) markers, tissue factor (TF), viral spike-protein and nucleoprotein (SP, NP), fibrinogen, platelets (CD41a). Viral particles in vascular cells were assessed by transmission electron microscopy (TEM). Cultured pericytes were infected with SARS-CoV-2 to measure TF expression and tubulisation of human pulmonary microvascular endothelial cells (HPMEC) was assessed upon vWF treatment.

RESULTS

IPVD was present in 16/66 COVID-19 patients with both liver and lung histology, with a younger age (62 vs 78yo), longer illness (25 vs 14 days), worsening hypoxemia (PaO2/FiO2 from 209 to 89), and more ventilatory support (63 vs 22%) compared to COVID-19/Non-IPVD. IPVD, absent in controls, were confirmed by chest-CT. COVID-19/IPVD liver histology showed portal microthrombosis in >82.5% of portal areas, with a thicker wall of αSMA/PDGFR-β+/ SP+/NP+ pericytes compared with COVID-19/Non-IPVD. Thrombosed portal venules correlated with αSMA+ area, whereas infected SP+/NP+ pericytes expressed TF. SARS-CoV-2 viral particles were observed in portal pericytes. In-vitro SARS-CoV-2 infection of pericytes up-regulated TF and induced endothelial cells to overexpress vWF, which expanded HPMEC tubules.

CONCLUSIONS

SARS-CoV-2 infection of liver pericytes elicits a local procoagulant response associated with extensive portal microthrombosis, IPVD and worsening respiratory failure in fatal COVID-19.

IMPACT AND IMPLICATIONS

Vascular involvement of the liver represents a serious complication of COVID-19 infection that must be considered in the work-up of patients with long-lasting and progressively worsening respiratory failure, as it may associate with the development of intrapulmonary vascular dilations. This clinical picture is associated with a pro-coagulant phenotype of portal venule pericytes, which is induced by SARS-CoV-2 infection of pericytes. Both observations provide a model that may apply, at least in part, to other vascular disorders of the liver, featuring obliterative portal venopathy, similarly characterized at the clinical level by development of hypoxemia and at the histological level, by phlebosclerosis and reduced caliber of the portal vein branches in the absence of cirrhosis. Moreover, our findings bring light to an as yet overlooked player of thrombosis pathophysiology, i.e. pericytes, which may provide novel therapeutic tools to halt prothrombotic mechanisms.

Aging Is Associated With Organ-Specific Alterations in the Level and Expression Pattern of von Willebrand Factor

BACKGROUND

VWF (von Willebrand factor) is an endothelial-specific procoagulant protein with a major role in thrombosis. Aging is associated with increased circulating levels of VWF, which presents a risk factor for thrombus formation.

METHODS

Circulating plasma, cellular protein, and mRNA levels of VWF were determined and compared in young and aged mice. Major organs were subjected to immunofluorescence analyses to determine the vascular pattern of VWF expression and the presence of platelet aggregates. An in vitro model of aging, using extended culture time of endothelial cells, was used to explore the mechanism of age-associated increased VWF levels.

RESULTS

Increased circulating plasma levels of VWF with elevated levels of larger multimers, indicative of VWF functional activity, were observed in aged mice. VWF mRNA and cellular protein levels were significantly increased in the brains, lungs, and livers but not in the kidneys and hearts of aged mice. Higher proportion of small vessels in brains, lungs, and livers of aged mice exhibited VWF expression compared with young, and this was concomitant with increased platelet aggregate formation. Prolonged culture of endothelial cells resulted in increased cell senescence that correlated with increased VWF expression; VWF expression was specifically detected in senescent cultured endothelial cells and abolished in response to p53 knockdown. A significantly higher proportion of VWF expressing endothelial cells in vivo exhibited senescence markers SA-β-Gal (senescence-associated β-galactosidase) and p53 in aged mouse brains compared with that of the young.

CONCLUSIONS

Aging elicits a heterogenic response in endothelial cells with regard to VWF expression, leading to organ-specific increase in VWF levels and alterations in vascular tree pattern of expression. This is concomitant with increased platelet aggregate formation. The age-associated increase in VWF expression may be modulated through the process of cell senescence, and p53 transcription factor contributes to its regulation.

Von Willebrand Factor as a Biomarker for Liver Disease - An Update

The von Willebrand factor (vWF) is best known for its role in the hemostatic pathway, aiding platelet adhesion and aggregation, as well as circulating along with coagulation factor VIII, prolonging its half-life. However, vWF is more than a hemostatic protein and is a marker of endothelial dysfunction in patients with cirrhosis. The levels of vWF increase progressively as cirrhosis progresses. Despite its qualitative defects, it can support and carry out its hemostatic role and contribute to a pro-coagulant disbalance. Moreover, it has been shown to be a good noninvasive marker for predicting clinically significant portal hypertension (CSPH). The vWF has been shown to predict decompensation and mortality among cirrhosis patients independently of the stage of liver disease and severity of portal hypertension. Increased vWF levels in the setting of endothelial injury predict bacterial translocation and systemic inflammation. The vWF-to-thrombocyte ratio (VITRO) score adds to the diagnostic ability of vWF alone in detecting CSPH non-invasively. Not only have vWF levels been shown to help predict the risk of hepatocellular carcinoma (HCC) among cirrhosis patients, but they also predict the risk of complications post-resection for HCC and response to systemic therapies. vWF-induced portal microthrombi have been purported to contribute to the pathogenesis of acute liver failure progression as well as non-cirrhotic portal hypertension. The prospect of modulation of vWF levels using drugs such as non-selective beta-blockers, statins, anticoagulants, and non-absorbable antibiotics and its use as a predictive biomarker for the response to these drugs needs to be explored.

Regulatory T cells in skin regeneration and wound healing

As the body's integumentary system, the skin is vulnerable to injuries. The subsequent wound healing processes aim to restore dermal and epidermal integrity and functionality. To this end, multiple tissue-resident cells and recruited immune cells cooperate to efficiently repair the injured tissue. Such temporally- and spatially-coordinated interplay necessitates tight regulation to prevent collateral damage such as overshooting immune responses and excessive inflammation. In this context, regulatory T cells (Tregs) hold a key role in balancing immune homeostasis and mediating cutaneous wound healing. A comprehensive understanding of Tregs' multifaceted field of activity may help decipher wound pathologies and, ultimately, establish new treatment modalities. Herein, we review the role of Tregs in orchestrating the regeneration of skin adnexa and catalyzing healthy wound repair. Further, we discuss how Tregs operate during fibrosis, keloidosis, and scarring.

The interplay between adsorption and aggregation of von Willebrand factor chains in shear flows

Von Willebrand factor (VWF) is a giant extracellular glycoprotein that carries out a key adhesive function during primary hemostasis. Upon vascular injury and triggered by the shear of flowing blood, VWF establishes specific interactions with several molecular partners in order to anchor platelets to collagen on the exposed subendothelial surface. VWF also interacts with itself to form aggregates that, adsorbed on the surface, provide more anchor sites for the platelets. However, the interplay between elongation and subsequent exposure of cryptic binding sites, self-association, and adsorption on the surface remained unclear for VWF. In particular, the role of shear flow in these three processes is not well understood. In this study, we address these questions by using Brownian dynamics simulations at a coarse-grained level of resolution. We considered a system consisting of multiple VWF-like self-interacting chains that also interact with a surface under a shear flow. By a systematic analysis, we reveal that chain-chain and chain-surface interactions coexist nontrivially to modulate the spontaneous adsorption of VWF and the posterior immobilization of secondary tethered chains. Accordingly, these interactions tune VWF's extension and its propensity to form shear-assisted functional adsorbed aggregates. Our data highlight the collective behavior VWF self-interacting chains have when bound to the surface, distinct from that of isolated or flowing chains. Furthermore, we show that the extension and the exposure to solvent have a similar dependence on shear flow, at a VWF-monomer level of resolution. Overall, our results highlight the complex interplay that exists between adsorption, cohesion, and shear forces and their relevance for the adhesive hemostatic function of VWF.

Gene silencing of endothelial von Willebrand factor reduces the susceptibility of human endothelial cells to SARS-CoV-2 infection

Mechanisms underlying vascular endothelial susceptibility to infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are not fully understood. Emerging evidence indicates that patients lacking von Willebrand factor (vWF), an endothelial hallmark, are less severely affected by SARS-CoV-2 infection, yet the precise role of endothelial vWF in modulating coronavirus entry into endothelial cells is unknown. In the present study, we demonstrated that effective gene silencing by short interfering RNA (siRNA) for vWF expression in resting human umbilical vein endothelial cells (HUVECs) significantly reduced by 56% the cellular levels of SARS-CoV-2 genomic RNA. Similar reduction in intracellular SARS-CoV-2 genomic RNA levels was observed in non-activated HUVECs treated with siRNA targeting angiotensin-converting enzyme 2 (ACE2), the cellular gateway to coronavirus. By integrating quantitative information from real-time PCR and high-resolution confocal imaging, we demonstrated that ACE2 gene expression and its plasma membrane localization in HUVECs were both markedly reduced after treatment with siRNA anti-vWF or anti-ACE2. Conversely, siRNA anti-ACE2 did not reduce endothelial vWF gene expression and protein levels. Finally, SARS-CoV-2 infection of viable HUVECs was enhanced by overexpression of vWF, which increased ACE2 levels. Of note, we found a similar increase in interferon-β mRNA levels following transfection with untargeted, anti-vWF or anti-ACE2 siRNA and pcDNA3.1-WT-VWF. We envision that siRNA targeting endothelial vWF will protect against productive endothelial infection by SARS-CoV-2 through downregulation of ACE2 expression and might serve as a novel tool to induce disease resistance by modulating the regulatory role of vWF on ACE2 expression.

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.

Functional changes in hemostasis during asexual and sexual parasitemia in a controlled human malaria infection

Decreased platelet count is an early phenomenon in asexual Plasmodium falciparum parasitemia, but its association with acute or long-term functional changes in platelets and coagulation is unknown. Moreover, the impact of gametocytemia on platelets and coagulation remains unclear. We investigated the changes in platelet number and function during early asexual parasitemia, gametocytemia and convalescence in 16 individuals participating in a controlled human malaria infection study, and studied its relationship with changes in total and active von Willebrand factor levels (VWF) and the coagulation system. Platelet activation and reactivity were determined by flow cytometry, and the coagulation system was assessed using different representative assays including antigen assays, activity assays and global functional assays. Platelet count was decreased during asexual blood stage infection but normalized during gametocytemia. Platelet P-selectin expression was slightly increased during asexual parasitemia, gametocytemia and at day 64. In contrast, platelet reactivity to different agonists remained unchanged, except a marked decrease in reactivity to low dose collagen-related peptide-XL. Thrombin generation and antigen assays did not show a clear activation of the coagulation during asexual parasitemia, whereas total and active VWF levels were markedly increased. During gametocytemia and on day 64, the endogenous thrombin potential, thrombin peak and velocity index were increased and prothrombin conversion and plasma prothrombin levels were decreased. We conclude that the decreased platelet count during asexual parasitemia is associated with increased active VWF levels (i.e. endothelial activation), but not platelet hyperreactivity or hypercoagulability, and that the increased platelet clearance in asexual parasitemia could cause spontaneous VWF-platelet complexes formation.

Development and Preliminary Testing of Porcine Blood-Derived Endothelial-like Cells for Vascular Tissue Engineering Applications: Protocol Optimisation and Seeding of Decellularised Human Saphenous Veins

Functional endothelial cells (EC) are a critical interface between blood vessels and the thrombogenic flowing blood. Disruption of this layer can lead to early thrombosis, inflammation, vessel restenosis, and, following coronary (CABG) or peripheral (PABG) artery bypass graft surgery, vein graft failure. Blood-derived ECs have shown potential for vascular tissue engineering applications. Here, we show the development and preliminary testing of a method for deriving porcine endothelial-like cells from blood obtained under clinical conditions for use in translational research. The derived cells show cobblestone morphology and expression of EC markers, similar to those seen in isolated porcine aortic ECs (PAEC), and when exposed to increasing shear stress, they remain viable and show mRNA expression of EC markers similar to PAEC. In addition, we confirm the feasibility of seeding endothelial-like cells onto a decellularised human vein scaffold with approximately 90% lumen coverage at lower passages, and show that increasing cell passage results in reduced endothelial coverage.

Tissue dynamics of von Willebrand factor characterized by a novel fluorescent protein-von Willebrand factor chimera

BACKGROUND

Tissue dynamics of von Willebrand factor (VWF) that are vital to its biological function have not been fully characterized.

OBJECTIVE

To develop a new fluorescent protein--VWF chimera (FP-VWF) that has similar hematologic function to wild-type VWF and use it to monitor the tissue dynamics of VWF distribution.

METHODS

Genotyping, platelet counting, tail bleeding time assay, agarose gels, western blot, platelet aggregation, proteolytic analysis, and ELISA were applied in characterizing the function of FP-VWF; fluorescence spectrometer and confocal fluorescence microscope were used to monitor the plasma and tissue distribution of FP-VWF.

RESULTS

The transgenic mice that carry the FP-VWF retain hematologic activity of VWF with plasma levels of FP-VWF reduced by 50% and there are reduced high molecular weight FP-VWF multimers compared to the wild-type mice. The GPIb-binding and ADAMTS-13 (A Disintegrin and Metalloprotease with ThrombSpondin type 1 motif, member 13) proteolytic efficiency of FP-VWF are similar to wild-type VWF. The tissue distribution of FP-VWF was probed directly through its intrinsic fluorescence at normal or stimulated status, which indicated that the medicine-stimulated endogenous FP-VWF seems primarily released from the aorta and cleared in the spleen. Similar results were observed in non-fluorescent mice through a standard immunofluorescence approach. The fluorescence signals of FP-VWF were also similar to the standard dye-based approach in detecting the FeCl3 -induced blood clotting in vivo.

CONCLUSIONS

Together, these results suggest that this novel FP-VWF chimera is valuable in probing the tissue dynamics of VWF in quite a few biological and pharmaceutical applications.

Reduced cleavage of von willebrand factor by ADAMTS13 is associated with microangiopathic acute kidney injury following trauma

Acute kidney injury (AKI) is common after trauma, but contributory factors are incompletely understood. Increases in plasma von Willebrand Factor (vWF) with concurrent decreases in ADAMTS13 are associated with renal microvascular thrombosis in other disease states, but similar findings have not been shown in trauma. We hypothesized that molecular changes in circulating vWF and ADAMTS13 promote AKI following traumatic injury. VWF antigen, vWF multimer composition and ADAMTS13 levels were compared in plasma samples from 16 trauma patients with and without trauma-induced AKI, obtained from the Prehospital Air Medical Plasma (PAMPer) biorepository. Renal histopathology and function, vWF and ADAMTS13 levels were assessed in parallel in a murine model of polytrauma and haemorrhage. VWF antigen was higher in trauma patients when compared with healthy controls [314% (253-349) vs. 100% (87-117)] [median (IQR)], while ADAMTS13 activity was lower [36.0% (30.1-44.7) vs. 100.0% (83.1-121.0)]. Patients who developed AKI showed significantly higher levels of high molecular weight multimeric vWF at 72-h when compared with non-AKI counterparts [32.9% (30.4-35.3) vs. 27.8% (24.6-30.8)]. Murine plasma cystatin C and vWF were elevated postpolytrauma model in mice, with associated decreases in ADAMTS13, and immunohistologic analysis demonstrated renal injury with small vessel plugs positive for fibrinogen and vWF. Following traumatic injury, the vWF-ADAMTS13 axis shifted towards a prothrombotic state in both trauma patients and a murine model. We further demonstrated that vWF-containing, microangiopathic deposits were concurrently produced as the prothrombotic changes were sustained during the days following trauma, potentially contributing to AKI development.

Toxic Metals and Subclinical Atherosclerosis in Carotid, Femoral, and Coronary Vascular Territories: The Aragon Workers Health Study

OBJECTIVE

Studies evaluating the association of metals with subclinical atherosclerosis are mostly limited to carotid arteries. We assessed individual and joint associations of nonessential metals exposure with subclinical atherosclerosis in 3 vascular territories. Approach and Results: One thousand eight hundred seventy-three Aragon Workers Health Study participants had urinary determinations of inorganic arsenic species, barium, cadmium, chromium, antimony, titanium, uranium, vanadium, and tungsten. Plaque presence in carotid and femoral arteries was determined by ultrasound. Coronary Agatston calcium score ≥1 was determined by computed tomography scan. Median arsenic, barium, cadmium, chromium, antimony, titanium, uranium, vanadium, and tungsten levels were 1.83, 1.98, 0.27, 1.18, 0.05, 9.8, 0.03, 0.66, and 0.23 μg/g creatinine, respectively. The adjusted odds ratio (95% CI) for subclinical atherosclerosis presence in at least one territory was 1.25 (1.03-1.51) for arsenic, 1.67 (1.22-2.29) for cadmium, and 1.26 (1.04-1.52) for titanium. These associations were driven by arsenic and cadmium in carotid, cadmium and titanium in femoral, and titanium in coronary territories and mostly remained after additional adjustment for the other relevant metals. Titanium, cadmium, and antimony also showed positive associations with alternative definitions of increased coronary calcium. Bayesian Kernel Machine Regression analysis simultaneously evaluating metal associations suggested an interaction between arsenic and the joint cadmium-titanium exposure.

CONCLUSIONS

Our results support arsenic and cadmium and identify titanium and potentially antimony as atherosclerosis risk factors. Exposure reduction and mitigation interventions of these metals may decrease cardiovascular risk in individuals without clinical disease.

Multifaceted Pathomolecular Mechanism of a VWF Large Deletion Involved in the Pathogenesis of Severe VWD

The present study demonstrates the dominant-negative impact of an in-frame large deletion on VWF biosynthesis and biogenesis of the WPBs.

The malformed WPBs/altered trafficking of its inflammatory cargos cause distresses in endothelial cell signaling pathways and phenotype.

An in-frame heterozygous large deletion of exons 4 through 34 of the von Willebrand factor (VWF) gene was identified in a type 3 von Willebrand disease (VWD) index patient (IP), as the only VWF variant. The IP exhibited severe bleeding episodes despite prophylaxis treatment, with a short VWF half-life after infusion of VWF/factor VIII concentrates. Transcript analysis confirmed transcription of normal VWF messenger RNA besides an aberrant deleted transcript. The IP endothelial colony-forming cells (ECFCs) exhibited a defect in the VWF multimers and Weibel-Palade bodies (WPBs) biogenesis, although demonstrating normal VWF secretion compared with healthy cells. Immunostaining of IP-ECFCs revealed subcellular mislocalization of WPBs pro-inflammatory cargos angiopoietin-2 (Ang2, nuclear accumulation) and P-selectin. Besides, the RNA-sequencing (RNA-seq) analysis showed upregulation of pro-inflammatory and proangiogenic genes, P-selectin, interleukin 8 (IL-8), IL-6, and GROα, copackaged with VWF into WPBs. Further, whole-transcriptome RNA-seq and subsequent gene ontology (GO) enrichment analysis indicated the most enriched GO-biological process terms among the differentially expressed genes in IP-ECFCs were regulation of cell differentiation, cell adhesion, leukocyte adhesion to vascular endothelial, blood vessel morphogenesis, and angiogenesis, which resemble downstream signaling pathways associated with inflammatory stimuli and Ang2 priming. Accordingly, our functional experiments exhibited an increased endothelial cell adhesiveness and interruption in endothelial cell–cell junctions of the IP-ECFCs. In conclusion, the deleted VWF has a dominant-negative impact on multimer assembly and the biogenesis of WPBs, leading to altered trafficking of their pro-inflammatory cargos uniquely, which, in turn, causes changes in cellular signaling pathways, phenotype, and function of the endothelial cells.

New Drug Targets to Prevent Death Due to Stroke: A Review Based on Results of Protein-Protein Interaction Network, Enrichment, and Annotation Analyses

This study used established biomarkers of death from ischemic stroke (IS) versus stroke survival to perform network, enrichment, and annotation analyses. Protein-protein interaction (PPI) network analysis revealed that the backbone of the highly connective network of IS death consisted of IL6, ALB, TNF, SERPINE1, VWF, VCAM1, TGFB1, and SELE. Cluster analysis revealed immune and hemostasis subnetworks, which were strongly interconnected through the major switches ALB and VWF. Enrichment analysis revealed that the PPI immune subnetwork of death due to IS was highly associated with TLR2/4, TNF, JAK-STAT, NOD, IL10, IL13, IL4, and TGF-β1/SMAD pathways. The top biological and molecular functions and pathways enriched in the hemostasis network of death due to IS were platelet degranulation and activation, the intrinsic pathway of fibrin clot formation, the urokinase-type plasminogen activator pathway, post-translational protein phosphorylation, integrin cell-surface interactions, and the proteoglycan-integrin extracellular matrix complex (ECM). Regulation Explorer analysis of transcriptional factors shows: (a) that NFKB1, RELA and SP1 were the major regulating actors of the PPI network; and (b) hsa-mir-26-5p and hsa-16-5p were the major regulating microRNA actors. In conclusion, prevention of death due to IS should consider that current IS treatments may be improved by targeting VWF, the proteoglycan-integrin-ECM complex, TGF-β1/SMAD, NF-κB/RELA and SP1.

Pre-surgical level of von Willebrand factor as an evident indicator of breast cancer recurrence

BACKGROUND

Endothelial and platelet activation as well as a disruption of haemostatic balance are crucial in cancer-dependent venous thromboembolism development.

OBJECTIVE

The aim of this study was to investigate the influence of von Willebrand factor (VWF), sE-selectin, sP-selectin as well as VWF/sE-selectin and sP-selectin/sE-selectin ratios on the probability of disease relapse in invasive breast carcinoma (IBrC) cases.

METHODS

Eighty-four patients with IA-IIB stage of IBrC who passed a comprehensive clinicopathologic evaluation were included in the study. Follow-up was completed in all patients with a 15.48 % recurrence rate. An immunoassay of VWF antigen, sE-selectin, sP-selectin, as well as an immunohistochemistry of oestrogen and progesterone receptors, human epidermal growth factor receptor 2 (HER2) and Ki67 was performed in all cases.

RESULTS

The VWF/sE-selectin ratio was significantly higher in patients with poorly differentiated tumours than in those with high-differentiated tumours. A positive correlation between VWF concentration and tumour grade was noted. Eleven of 13 events happened in patients with VWF value below 600 mU/mL with recurrence rate of 25%, but only two events occurred in subject with VWF values above the 600 mU/mL (5%; P= 0.0028).

CONCLUSIONS

Our study show that VWF could be considered as a suitable biomarker of breast cancer relapse.

Blood Biomarker Panels for the Early Prediction of Stroke-Associated Complications

Background Acute decompensated heart failure (ADHF) and respiratory tract infections (RTIs) are potentially life-threatening complications in patients experiencing stroke during hospitalization. We aimed to test whether blood biomarker panels might predict these complications early after admission. Methods and Results Nine hundred thirty-eight patients experiencing ischemic stroke were prospectively recruited in the Stroke-Chip study. Post-stroke complications during hospitalization were retrospectively evaluated. Blood samples were drawn within 6 hours after stroke onset, and 14 biomarkers were analyzed by immunoassays. Biomarker values were normalized using log-transformation and Z score. PanelomiX algorithm was used to select panels with the best accuracy for predicting ADHF and RTI. Logistic regression models were constructed with the clinical variables and the biomarker panels. The additional predictive value of the panels compared with the clinical model alone was evaluated by receiver operating characteristic curves. An internal validation through a 10-fold cross-validation with 3 repeats was performed. ADHF and RTI occurred in 19 (2%) and 86 (9.1%) cases, respectively. Three-biomarker panels were developed as predictors: vascular adhesion protein-1 >5.67, NT-proBNP (N-terminal pro-B-type natriuretic peptide) >4.98 and d-dimer >5.38 (sensitivity, 89.5%; specificity, 71.7%) for ADHF; and interleukin-6 >3.97, von Willebrand factor >3.67, and d-dimer >4.58 (sensitivity, 82.6%; specificity, 59.8%) for RTI. Both panels independently predicted stroke complications (panel for ADHF: odds ratio [OR] [95% CI], 10.1 [3-52.2]; panel for RTI: OR, 3.73 [1.95-7.14]) after adjustment by clinical confounders. The addition of the panel to clinical predictors significantly improved areas under the curve of the receiver operating characteristic curves in both cases. Conclusions Blood biomarkers could be useful for the early prediction of ADHF and RTI. Future studies should assess the usefulness of these panels in front of patients experiencing stroke with respiratory symptoms such as dyspnea.

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.

The emergent phenomenon of aspirin resistance: insights from genetic association studies

Despite the clinical benefits of aspirin, the interindividual variation in response to this antiplatelet drug is considerable. The manifestation of aspirin resistance (AR) is frequently observed, although this complex process remains poorly understood. While AR etiology is likely to be multifactorial, genetic factors appear to be preponderant. According to several genetic association studies, both genome-wide and candidate gene studies, numerous SNPs in cyclooxygenase, thromboxane and platelet receptors-related genes have been identified as capable of negatively affecting aspirin action. Thus, it is essential to understand the clinical relevance of AR-related SNPs as potential predictive and prognostic biomarkers as they may be essential to defining the AR phenotype.

Plasma Level of von Willebrand Factor Propeptide at Diagnosis: A Marker of Subsequent Renal Dysfunction in Autoimmune Rheumatic Diseases

Introduction:

Patients with systemic autoimmune rheumatic diseases (SARDs) such as rheumatoid arthritis, systemic lupus erythematosus (SLE), Sjögren syndrome, and systemic sclerosis, which are chronic inflammatory diseases, are prone to develop renal dysfunction, which is related to vascular endothelial cell damage.

Material and Methods:

We evaluated plasma levels of von Willebrand factor (VWF), VWF propeptide (VWF-pp), disintegrin-like and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), and VWF multimer pattern in patients with SARDs at diagnosis and investigated whether they may serve as markers to identify patients destined to develop renal dysfunction within 1 year. Renal dysfunction was defined as subsequent reduced estimated glomerular filtration rate (eGFR) by >25% or the new appearance of abnormal urine findings such as proteinuria (protein > 30 mg/dL) or hematuria (red blood cells >20/HPF in urine sediments). Overall, 63 patients with SARDs were studied.

Results and Conclusions:

We observed a significant increase of VWF-pp and a significant decrease of ADAMTS13 in patients with SARDs compared with normal healthy controls. The highest level of VWF-pp was observed in patients with SLE among the groups. The levels of VWF and multimer pattern of VWF were not different compared with normal healthy controls. Von Willebrand factor propeptide predicted a subsequent decrease in eGFR at a cutoff point of 210% (sensitivity, 78.6%; specificity, 73.5%) and new urinary abnormal findings at a cutoff point of 232% (sensitivity, 77.8%; specificity, 77.8%) Using these cutoff points, multivariable analysis revealed that VWF-pp was a significant risk factor for renal dysfunction at an odds ratio of 8.78 and 22.8, respectively, and may lead to a new therapeutic approach to prevent vasculitis and renal dysfunction.

Abnormal platelet activity in dogs and cats - impact and measurement

Abnormal platelet activity can either lead to bleeding tendencies or inappropriate thrombus formation and can occur secondarily to a wide variety of disease processes, with a range of clinical consequences and severity. This article will discuss the pathophysiology of platelet function abnormalities and consider a logical diagnostic approach applicable to veterinary practice. Recent advances in platelet function testing will then be discussed, with regards to detection of platelet dysfunction and tailoring of pharmacological manipulation. Although many of these tests are still confined to research or academic institutions, techniques for indirectly assessing platelet function are starting to become more widely available. Although we still require further research to develop guidelines for the use of these tests in clinical decision-making, the recent advances in this field are an exciting step forward in being able to detect and manage platelet dysfunction in both primary care and referral practice.

Serum von Willebrand factor for early diagnosis of lung adenocarcinoma in patients with type 2 diabetes mellitus

BACKGROUND

The elevation of plasma von Willebrand factor (vWF) has been proposed to be a predictor of lung cancer. Type 2 diabetes mellitus (T2DM) causes endothelial activation, resulting in the secretion of vWF. However, the role of vWF in patients with T2DM complicated with lung cancer remains unclear.

AIM

To investigate the clinical value of serum vWF as a tumor marker in patients with T2DM combined with lung adenocarcinoma in situ (AIS).

METHODS

This study enrolled 43 patients with T2DM combined with lung AIS (T2DM + AIS group), 43 patients with T2DM alone (T2DM group), 43 patients with lung AIS alone (AIS group), and 43 healthy volunteers (control group). The serum levels of vWF, insulin-like growth factor 1, and insulin-like growth factor binding protein 3 were determined. Multiple linear stepwise regression was performed to determine the correlations among variables.

RESULTS

Serum concentration of vWF in the T2DM + AIS group was significantly higher than those in the T2DM, AIS, and control groups (P < 0.05). Serum vWF levels in the T2DM and AIS groups were significantly higher than that in the control group (P < 0.05). There was no significant difference in serum vWF level between the T2DM and AIS groups. In the T2DM + AIS group, serum vWF was independently associated and positively correlated with serum levels of insulin-like growth factor 1 and insulin-like growth factor binding protein 3 (P < 0.05).

CONCLUSION

Serum vWF level may represent a novel biomarker for the early diagnosis of lung AIS.

Clinical pharmacology of caplacizumab for the treatment of patients with acquired thrombotic thrombocytopenic purpura

Introduction: Caplacizumab is a humanized anti-von Willebrand Factor (vWF) Nanobody® for the treatment of acquired Thrombotic Thrombocytopenic Purpura (aTTP). Caplacizumab targets the A1-domain of vWF, inhibiting the interaction between vWF and platelets. Clinical studies conducted in aTTP patients confirmed the rapid and sustained complete suppression of the vWF activity using an initial intravenous dose of 10 mg, and a maintenance subcutaneous 10 mg daily dosing regimen, with corresponding favorable efficacy and safety profiles. Areas covered: The pharmacokinetics of caplacizumab are non-linear, characterized by a target-mediated disposition and the exposure is dependent upon drug and target concentration over time. The pharmacokinetics of caplacizumab are predictable when considering the turn-over of the circulating vWF and its modulation by the drug over time. Renal and hepatic impairment are not expected to influence the exposure to the drug, and no direct or indirect drug-drug pharmacokinetic interactions are anticipated based on the mechanism of action and the specificity of the pharmacodynamic effect of caplacizumab. Expert opinion: Caplacizumab prevents the interaction between vWF and platelets, offering a direct and rapid therapeutic intervention to stop microthrombosis. The combination of caplacizumab with plasma exchange and immunosuppression represents an important, potentially life-saving advance in the treatment of aTTP patients.

Early and late endothelial response in breast cancer metastasis in mice: simultaneous quantification of endothelial biomarkers using a mass spectrometry-based method

The endothelium plays an important role in cancer metastasis, but the mechanisms involved are still not clear. In the present work, we characterised the changes in endothelial function at early and late stages of breast cancer progression in an orthotopic model of murine mammary carcinoma (4T1 cells). Endothelial function was analysed based on simultaneous microflow liquid chromatography–tandem mass spectrometry using multiple reaction monitoring (microLC/MS-MRM) quantification of 12 endothelium-related biomarkers, including those reflecting glycocalyx disruption – syndecan-1 (SDC-1), endocan (ESM-1); endothelial inflammation – vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), E-selectin (E-sel); endothelial permeability – fms-like tyrosine kinase 1 (FLT-1), angiopoietin 2 (Angpt-2); and haemostasis – von Willebrand factor (vWF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), as well as those that are pathophysiologically linked to endothelial function – adrenomedullin (ADM) and adiponectin (ADN). The early phase of metastasis in mouse plasma was associated with glycocalyx disruption (increased SDC-1 and ESM-1), endothelial inflammation [increased soluble VCAM-1 (sVCAM-1)] and increased vascular permeability (Angpt-2). During the late phase of metastasis, additional alterations in haemostasis (increased PAI-1 and vWF), as well as a rise in ADM and substantial fall in ADN concentration, were observed. In conclusion, in a murine model of breast cancer metastasis, we identified glycocalyx disruption, endothelial inflammation and increased endothelial permeability as important events in early metastasis, while the late phase of metastasis was additionally characterised by alterations in haemostasis.

Summary: A microLC/MS-MRM-based approach for simultaneous determination of endothelium-related biomarkers identified glycocalyx disruption, endothelial inflammation and increased endothelial permeability as important events in early pulmonary metastasis in a murine model of breast cancer metastasis.

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.

Redox proteomic insights into involvement of clathrin-mediated endocytosis in silver nanoparticles toxicity to Mytilus galloprovincialis

Clathrin-mediated endocytosis is a major mode of nanoparticle (NP) internalization into cells. However, influence of internalization routes on nanoparticle toxicity is poorly understood. Here, we assess the impact of blocking clathrin-mediated endocytosis upon silver NP (AgNP) toxicity to gills and digestive glands of the mussel Mytilusgalloprovincialisusing the uptake inhibitor, amantadine. Animals were exposed for 12h to AgNP (< 50 nm) in the presence and absence of amantadine. Labeling of oxidative protein modifications, either thiol oxidation, carbonyl formation or both in two-dimensional electrophoresis separations revealed 16 differentially affected abundance spots. Amongst these, twelve hypothetical proteins were successfully identified by peptide mass fingerprinting (MALDI TOF-MS/MS). The proteins identified are involved in buffering redox status or in cytoprotection. We conclude that blockade of clathrin-mediated endocytosis protected against NP toxicity, suggesting this uptake pathway facilitates toxicity. Lysosomal degradation and autophagy are major mechanisms that might be induced to mitigate NP toxicity.

Effect of Pneumatic Tubing System Transport on Platelet Apheresis Units

Platelet apheresis units are transfused into patients to mitigate or prevent bleeding. In a hospital, platelet apheresis units are transported from the transfusion service to the healthcare teams via two methods: a pneumatic tubing system (PTS) or ambulatory transport. Whether PTS transport affects the activity and utility of platelet apheresis units is unclear. We quantified the gravitational forces and transport time associated with PTS and ambulatory transport within our hospital. Washed platelets and supernatants were prepared from platelet apheresis units prior to transport as well as following ambulatory or PTS transport. For each group, we compared resting and agonist-induced platelet activity and platelet aggregate formation on collagen or von Willebrand factor (VWF) under shear, platelet VWF-receptor expression and VWF multimer levels. Subjection of platelet apheresis units to rapid acceleration/deceleration forces during PTS transport did not pre-activate platelets or their ability to activate in response to platelet agonists as compared to ambulatory transport. Platelets within platelet apheresis units transported via PTS retained their ability to adhere to surfaces of VWF and collagen under shear, although platelet aggregation on collagen and VWF was diminished as compared to ambulatory transport. VWF multimer levels and platelet GPIb receptor expression was unaffected by PTS transport as compared to ambulatory transport. Subjection of platelet apheresis units to PTS transport did not significantly affect the baseline or agonist-induced levels of platelet activation as compared to ambulatory transport. Our case study suggests that PTS transport may not significantly affect the hemostatic potential of platelets within platelet apheresis units.

Prognostic value of von Willebrand factor in patients with atrial fibrillation: A meta-analysis

BACKGROUND

Studies on the prognostic role of von Willebrand factor (vWF) in patients with atrial fibrillation (AF) are conflicting. This meta-analysis aimed to evaluate the association of elevated circulating vWF level with adverse outcomes in patients with AF.

METHODS

PubMed and Embase were used to search literature through August 2017. Prospective observational studies that evaluated the association of elevated vWF level with major adverse cardiac events (MACEs) and all-cause mortality in patients with AF were deemed eligible. The MACEs included death, stroke/transient ischemic attack, heart failure, myocardial infarction, and systemic/peripheral embolism.

RESULTS

A total of 6 studies were included this meta-analysis. Patients with AF with the highest vWF level were independently associated with greater risk of MACEs (risk ratio [RR] 2.20; 95% confidence intervals [CI] 1.61-3.01) and all-cause mortality (RR 1.63; 95% CI 1.39-1.91). Subgroup analysis showed that the prognostic role of higher vWF level was consistently observed in each defined subgroups.

CONCLUSION

Patients with AF with elevated vWF level are independently associated with a higher risk of MACEs and all-cause mortality. However, more well-designed prospective studies are needed to confirm these findings.

The Role of von Willebrand Factor, ADAMTS13, and Cerebral Artery Thrombus Composition in Patient Outcome Following Mechanical Thrombectomy for Acute Ischemic Stroke

Background

The aim of the study was to investigate the role of von Willebrand factor (vWF), the vWF-cleaving protease, ADAMTS13, the composition of thrombus, and patient outcome following mechanical cerebral artery thrombectomy in patients with acute ischemic stroke.

Material/Methods

A prospective cohort study included 131 patients with ischemic stroke (<6 hours) with or without intravenous thrombolysis. Interventional procedure parameters, hemocoagulation markers, vWF, ADAMTS13, and histological examination of the extracted thrombi were performed. The National Institutes of Health Stroke Scale (NIHSS) score was used on hospital admission, after 24 hours, at day 7; the three-month modified Rankin Scale score was used.

Results

Mechanical thrombectomy resulted in a Treatment in Cerebral Ischemia (TICI) score of 2–3, with recanalization in 89% of patients. Intravenous thrombolysis was used in 101 (78%). Patients with and without intravenous thrombolysis therapy had a good clinical outcome (score 0–2) in 47% of cases (P=0.459) using the three-month modified Rankin Scale. Patients with a National Institutes of Health Stroke Scale (NIHSS) score ≥15 had significantly increased vWF levels (P=0.003), and a significantly increased vWF: ADAMTS13 ratio (P=0.038) on hospital admission. Significant correlation coefficients were found for plasma vWF and thrombo-embolus vWF (r=0.32), platelet (r=0.24), and fibrin (r=0.26) levels. In the removed thrombus, vWF levels were significantly correlated with platelet count (r=0.53), CD31-positive cells (r=0.38), and fibrin (r=0.48).

Conclusions

In patients with acute ischemic stroke, mechanical cerebral artery thrombectomy resulted in a good clinical outcome in 47% of cases, with and without intravenous thrombolysis therapy.

Alterations in NO- and PGI2- dependent function in aorta in the orthotopic murine model of metastatic 4T1 breast cancer: relationship with pulmonary endothelial dysfunction and systemic inflammation

Background

Patients with cancer develop endothelial dysfunction and subsequently display a higher risk of cardiovascular events. The aim of the present work was to examine changes in nitric oxide (NO)- and prostacyclin (PGI₂)-dependent endothelial function in the systemic conduit artery (aorta), in relation to the formation of lung metastases and to local and systemic inflammation in a murine orthotopic model of metastatic breast cancer.

Methods

BALB/c female mice were orthotopically inoculated with 4T1 breast cancer cells. Development of lung metastases, lung inflammation, changes in blood count, systemic inflammatory response (e.g. SAA, SAP and IL-6), as well as changes in NO- and PGI₂-dependent endothelial function in the aorta, were examined 2, 4, 5 and 6 weeks following cancer cell transplantation.

Results

As early as 2 weeks following transplantation of breast cancer cells, in the early metastatic stage, lungs displayed histopathological signs of inflammation, NO production was impaired and nitrosylhemoglobin concentration in plasma was decreased. After 4 to 6 weeks, along with metastatic development, progressive leukocytosis and systemic inflammation (as seen through increased SAA, SAP, haptoglobin and IL-6 plasma concentrations) were observed. Six weeks following cancer cell inoculation, but not earlier, endothelial dysfunction in aorta was detected; this involved a decrease in basal NO production and a decrease in NO-dependent vasodilatation, that was associated with a compensatory increase in cyclooxygenase-2 (COX-2)- derived PGI₂ production.

Conclusions

In 4 T1 metastatic breast cancer in mice early pulmonary metastasis was correlated with lung inflammation, with an early decrease in pulmonary as well as systemic NO availability. Late metastasis was associated with robust, cancer-related, systemic inflammation and impairment of NO-dependent endothelial function in the aorta that was associated with compensatory upregulation of the COX-2-derived PGI₂ pathway.

Low dose cadmium upregulates the expression of von Willebrand factor in endothelial cells

Cadmium (Cd) is a persistent and widespread environmental pollutant of continuing worldwide concern. Previous studies have suggested that Cd exposure increases the risk of cardiovascular diseases, such as atherosclerosis and hypertension. However, the underlying mechanisms are poorly understood. In this study, we observed that low dose Cd treatment induced von Willebrand factor (vWF) expression in vascular endothelial cells in mouse lung and kidney tissues. In vitro analysis showed that 1 μM Cd specifically upregulated vWF mRNA and protein expression in human umbilical vein endothelial cells (HUVECs), indicating that Cd targets vascular endothelial cells even at relatively low concentrations. Further study demonstrated that nuclear factor kappa B (NF-κB) and GATA3, two established transcription regulators of the vWF gene, were not altered in the presence of Cd. However, ETS-related gene (ERG) was significantly induced by 1 μM Cd. When ERG was knocked down by siRNA, Cd induced upregulation of vWF was totally blocked. Chromatin immunoprecipitation (ChIP) assay showed that Cd increases the binding of ERG on the -56 ETS motif on the human vWF promoter. These results indicated that ERG mediated the increased expression of vWF by Cd. Since vWF is a key regulator for vascular homeostasis, our findings may provide a novel mechanism for understanding low dose Cd induced development of vascular diseases.

Sensitive immunoassay of von Willebrand factor based on fluorescence resonance energy transfer between graphene quantum dots and Ag@Au nanoparticles

Graphene quantum dots (GQDs) and core-shell Ag@Au nanoparticles (Ag@Au NPs) were synthetized and they were characterized by transmission electron microscope and X-ray photoelectron spectra, respectively. Von Willebrand factor antibody (vWF Ab) was bound on Ag@Au NPs to construct Ag@Au-Ab nanocomposites (Ag@Au-Ab NCs). The fluorescence of GQDs could be effectively quenched by the prepared nanocomposites owing to fluorescence resonance energy transfer (FRET). The immunoreaction between vWF and Ag@Au-Ab NCs resulted in the declined FRET efficiency and a degree of fluorescence recovery of GQDs. The fluorescence intensity change was found to be proportional to the logarithm of the vWF concentration in the range of 0.1 pg mL^-1-10 ng mL^-1 with a detection limit of 30 fg mL^-1. The proposed fluorescence sensor was employed to investigate the relationship between the release of vWF and the oxidation-injury degree of vascular endothelial cells. The experimental results indicate that the vWF content in the growth medium was enhanced and the cell injury was intensified when the contact time of the cells with H₂O₂ was increased.

Verification of a proteomic biomarker panel to diagnose minor stroke and transient ischaemic attack: phase 1 of SpecTRA, a large scale translational study

OBJECTIVE

To derive a plasma biomarker protein panel from a list of 141 candidate proteins which can differentiate transient ischaemic attack (TIA)/minor stroke from non-cerebrovascular (mimic) conditions in emergency department (ED) settings.

DESIGN

Prospective clinical study (#NCT03050099) with up to three timed blood draws no more than 36 h following symptom onset. Plasma samples analysed by multiple reaction monitoring-mass spectrometry (MRM-MS).

PARTICIPANTS

Totally 545 participants suspected of TIA enrolled in the EDs of two urban medical centres.

OUTCOMES

90-day, neurologist-adjudicated diagnosis of TIA informed by clinical and radiological investigations.

RESULTS

The final protein panel consists of 16 proteins whose patterns show differential abundance between TIA and mimic patients. Nine of the proteins were significant univariate predictors of TIA [odds ratio (95% confidence interval)]: L-selectin [0.726 (0.596-0.883)]; Insulin-like growth factor-binding protein 3 [0.727 (0.594-0.889)]; Coagulation factor X [0.740 (0.603-0.908)]; Serum paraoxonase/lactonase 3 [0.763 (0.630-0.924)]; Thrombospondin-1 [1.313 (1.081-1.595)]; Hyaluronan-binding protein 2 [0.776 (0.637-0.945)]; Heparin cofactor 2 [0.775 (0.634-0.947)]; Apolipoprotein B-100 [1.249 (1.037-1.503)]; and von Willebrand factor [1.256 (1.034-1.527)]. The scientific plausibility of the panel proteins is discussed.

CONCLUSIONS

Our panel has the potential to assist ED physicians in distinguishing TIA from mimic patients.

Network-based analysis of omics data: the LEAN method

Motivation

Most computational approaches for the analysis of omics data in the context of interaction networks have very long running times, provide single or partial, often heuristic, solutions and/or contain user-tuneable parameters.

Results

We introduce local enrichment analysis (LEAN) for the identification of dysregulated subnetworks from genome-wide omics datasets. By substituting the common subnetwork model with a simpler local subnetwork model, LEAN allows exact, parameter-free, efficient and exhaustive identification of local subnetworks that are statistically dysregulated, and directly implicates single genes for follow-up experiments.

Evaluation on simulated and biological data suggests that LEAN generally detects dysregulated subnetworks better, and reflects biological similarity between experiments more clearly than standard approaches. A strong signal for the local subnetwork around Von Willebrand Factor (VWF), a gene which showed no change on the mRNA level, was identified by LEAN in transcriptome data in the context of the genetic disease Cerebral Cavernous Malformations (CCM). This signal was experimentally found to correspond to an unexpected strong cellular effect on the VWF protein. LEAN can be used to pinpoint statistically significant local subnetworks in any genome-scale dataset.

Availability and Implementation

The R-package LEANR implementing LEAN is supplied as supplementary material and available on CRAN (https://cran.r-project.org).

Supplementary information

Supplementary data are available at Bioinformatics online.

Gastrointestinal angiodysplasia and bleeding in von Willebrand disease

Von Willebrand disease (VWD), the most common genetic bleeding disorder, is characterised by a quantitative or qualitative defect of von Willebrand factor (VWF). Patients with VWD suffer from mucocutaneous bleeding, of severity usually proportional to the degree of VWF defect. In particular, gastrointestinal bleeding associated with angiodysplasia is often a severe symptom of difficult management. This review focuses on the pathophysiology, diagnosis and treatment of VWD-associated gastrointestinal angiodysplasia and related bleeding.

Von Willebrand factor protects against acute CCl4-induced hepatotoxicity through phospho-p38 MAPK signaling pathway inhibition

The blood glycoprotein von Willebrand factor (vWF) is involved in coagulopathy and inflammation; however, its role in the pathogenesis of acute liver failure, as suggested by its higher expression levels in such patients, remains unknown. In this study, vWF-knockout (KO) mice showed more severe carbon tetrachloride (CCl₄)-induced liver injury than wild-type mice. Patients with acute liver injury also showed elevated vWF protein activity and expression in liver tissues, as compared to healthy individuals. Using the mouse model and cultured human umbilical vein endothelial cells (HUVECs), CCl₄ was found to directly increase vWF protein expression through interaction with the highly expressed vWF receptor, GPIbα. Microarray analysis revealed that the genes showing the most differential expression in response to CCl₄-induced liver injury and vWF deficiency were related to the MAPK signaling pathway. Subsequent inhibition of vWF protein activity in HUVECs led to activation of the MAPK signal pathway and elevated production of FGL2, and treatment with a phospho-p38 inhibitor suppressed the CCl₄-induced production of FGL2. Exposure of liver sinusoidal endothelial cells isolated from the vWF-KO acute liver injury model mice to phospho-p38 inhibitor also decreased FGL2 expression. The vWF/GPIbα axis plays a protective role against development of acute liver injury by attenuating FGL2 production through the MAPK signaling pathway. Collectively, these data provide insight into the pathogenesis of acute liver injury and a potential novel strategy for its treatment.

The collαgen III fibril has a "flexi-rod" structure of flexible sequences interspersed with rigid bioactive domains including two with hemostatic roles

Collagen III is critical to the integrity of blood vessels and distensible organs, and in hemostasis. Examination of the human collagen III interactome reveals a nearly identical structural arrangement and charge distribution pattern as for collagen I, with cell interaction domains, fibrillogenesis and enzyme cleavage domains, several major ligand-binding regions, and intermolecular crosslink sites at the same sites. These similarities allow heterotypic fibril formation with, and substitution by, collagen I in embryonic development and wound healing. The collagen III fibril assumes a "flexi-rod" structure with flexible zones interspersed with rod-like domains, which is consistent with the molecule's prominence in young, pliable tissues and distensible organs. Collagen III has two major hemostasis domains, with binding motifs for von Willebrand factor, α2β1 integrin, platelet binding octapeptide and glycoprotein VI, consistent with the bleeding tendency observed with COL3A1 disease-causing sequence variants.

Von Willebrand Factor: Multimeric Structure and Functional Activity in Patients With Atrial Fibrillation With and Without Oral Anticoagulation

von Willebrand factor (vWF) is a multimeric glycoprotein present in blood plasma. It is synthesized in megakaryocytes and endothelial cells, secreted into circulation in the form of high-molecular-weight multimers (HMWMs), and cleaved into shorter, less active multimers by ADAMTS13. It is essential for platelet adhesion and aggregation. Previous studies have investigated the relationship between vWF levels and thromboembolic events with little regard to vWF multimeric structure. Patients with atrial fibrillation (AF) exhibit higher plasma vWF and lower ADAMTS13 levels. One hundred seven patients with AF, 51 anticoagulated and 56 nonanticoagulated, were eligible for the study. Plasma samples were analyzed for vWF antigen, vWF activity, and ADAMTS13; vWF multimers were analyzed by Western blot in 1% to 1.3% sodium dodecyl sulfate agarose gel electrophoresis. Patients with AF without oral anticoagulation (OAC) had significantly higher vWF plasma levels (154.00 [75-201] UI/dL) and vWF activity (60.00% [20%-210%]) compared to patients with OAC (133.50 [90-192] UI/dL, P = <.001; 50.00% [20%-160%], P = .02). Both were specially decreased in patients treated with acenocumarin. Patients without OAC also showed lower ADAMTS13 levels and presence of vWF HMWMs. Patients with AF show higher plasma levels and vWF activity. Moreover, treatment with traditional OAC (acenocumarin) significantly reduced vWF levels. Patients without OAC might have an increased risk of thrombotic events showing lower ADAMTS13 and higher vWF levels. Patients with stroke had higher plasma levels, vWF activity, and HMWMs. Our study suggests that increased vWF levels and presence of HMWMs could be related to cerebrovascular disease and may represent useful biomarkers for stroke in AF.

Functional assessment of von Willebrand factor expression by cancer cells of non-endothelial origin

Von Willebrand factor (VWF) is a highly adhesive procoagulant molecule that mediates platelet adhesion to endothelial and subendothelial surfaces. Normally it is expressed exclusively in endothelial cells (ECs) and megakaryocytes. However, a few studies have reported VWF detection in cancer cells of non-endothelial origin, including osteosarcoma. A role for VWF in cancer metastasis has long been postulated but evidence supporting both pro- and anti-metastatic roles for VWF has been presented. We hypothesized that the role of VWF in cancer metastasis is influenced by its cellular origin and that cancer cell acquisition of VWF expression may contribute to enhanced metastatic potential. We demonstrated de novo expression of VWF in glioma as well as osteosarcoma cells. Endothelial monolayer adhesion, transmigration and extravasation capacities of VWF expressing cancer cells were shown to be enhanced compared to non-VWF expressing cells, and were significantly reduced as a result of VWF knock down. VWF expressing cancer cells were also detected in patient tumor samples of varying histologies. Analyses of the mechanism of transcriptional activation of the VWF in cancer cells demonstrated a pattern of trans-activating factor binding and epigenetic modifications consistent overall with that observed in ECs. These results demonstrate that cancer cells of non-endothelial origin can acquire de novo expression of VWF, which can enhance processes, including endothelial and platelet adhesion and extravasation, that contribute to cancer metastasis.

Pulmonary endothelial activation caused by extracellular histones contributes to neutrophil activation in acute respiratory distress syndrome

BACKGROUND

During the acute respiratory distress syndrome (ARDS), neutrophils play a central role in the pathogenesis, and their activation requires interaction with the endothelium. Extracellular histones have been recognized as pivotal inflammatory mediators. This study was to investigate the role of pulmonary endothelial activation during the extracellular histone-induced inflammatory response in ARDS.

METHODS

ARDS was induced in male C57BL/6 mice by intravenous injection with lipopolysaccharide (LPS) or exogenous histones. Concurrent with LPS administration, anti-histone H4 antibody (anti-H4) or non-specific IgG was administered to study the role of extracellular histones. The circulating von Willebrand factor (vWF) and soluble thrombomodulin (sTM) were measured with ELISA kits at the preset time points. Myeloperoxidase (MPO) activity in lung tissue was measured with a MPO detection kit. The translocation of P-selectin and neutrophil infiltration were measured by immunohistochemical detection. For in vitro studies, histone H4 in the supernatant of mouse lung vascular endothelial cells (MLVECs) was measured by Western blot. The binding of extracellular histones with endothelial membrane was examined by confocal laser microscopy. Endothelial P-selectin translocation was measured by cell surface ELISA. Adhesion of neutrophils to MLVECs was assessed with a color video digital camera.

RESULTS

The results showed that during LPS-induced ARDS extracellular histones caused endothelial and neutrophil activation, as seen by P-selectin translocation, release of vWF, an increase of circulating sTM, lung neutrophil infiltration and increased MPO activity. Extracellular histones directly bound and activated MLVECs in a dose-dependent manner. On the contrary, the direct stimulatory effect of exogenous histones on neutrophils was very limited, as measured by neutrophil adhesion and MPO activity. With the contribution of activated endothelium, extracellular histones could effectively activating neutrophils. Both inhibiting the endothelial activation with an anti-toll like receptor (TLR) antibody and inhibiting the interaction of the endothelium with neutrophil using an anti-P-selectin antibody decreased the degree of neutrophil activation.

CONCLUSIONS

Extracellular histones are pro-inflammatory mediators in LPS-induced ARDS in mice. In addition to direct action to neutrophils, extracellular histones promote neutrophil adhesion and subsequent activation by first activating the pulmonary endothelium via TLR signaling. Thus, endothelial activation is important for extracellular histone-induced inflammatory injury.

A Japanese cross-sectional multicentre study of biomarkers associated with cardiovascular disease in smokers and non-smokers

We performed a cross-sectional, multicentre study in Japan to detect the differences in biomarkers of exposure and cardiovascular biomarkers between smokers and non-smokers. Several clinically relevant cardiovascular biomarkers differed significantly between smokers and non-smokers, including lipid metabolism (high-density lipoprotein cholesterol concentrations – lower in smokers), inflammation (fibrinogen and white blood cell count – both higher in smokers), oxidative stress (8-epi-prostaglandin F_2α – higher in smokers) and platelet activation (11-dehydro-thromboxane B₂ – higher in smokers) (p ≤ 0.0001). These results provide further evidence showing that cardiovascular biomarkers can discriminate smokers from non-smokers, and could be used to evaluate the risks associated with tobacco products.

Expressão imunoistoquímica da endoglina (CD105) e do fator de von Willebrand em carcinoma epidermoide oral e sua relação com parâmetros clinicopatológicos

Resumo Contexto A angiogênese tem sido associada à progressão de neoplasias malignas e, embora haja estudos acerca de marcadores angiogênicos no carcinoma epidermoide oral (CEO), existem resultados conflitantes na literatura. Objetivos Avaliar a expressão imunoistoquímica do CD105 e do fator de von Willebrand (FvW) em CEO e sua relação com parâmetros clínicos do tumor. Métodos A imunoexpressão dos referidos biomarcadores foi analisada em 30 casos de CEO e correlacionada a parâmetros clínicos do tumor (idade e sexo dos pacientes, localização anatômica e estadiamento clínico Tumor, Nodo e Metástase, TNM). Resultados A imunomarcação com o anticorpo anti-FvW foi mais efetiva que a do CD105 no CEO. No que concerne à localização anatômica, o assoalho bucal e a região retromolar apresentaram diferenças estatisticamente significativas quanto aos índices angiogênicos (p = 0,004), determinados pela técnica de contagem microvascular (MVC). Não houve relação estatisticamente significativa entre o estadiamento clínico TNM e os índices angiogênicos, com os dois biomarcadores. Conclusões Com base nos achados deste estudo, sugere-se um envolvimento da neoformação vascular na carcinogênese oral, embora não tenha sido evidenciada associação significativa com o estágio clínico da lesão.

The prothrombotic state associated with obesity-induced hypertension is reduced by cocoa and its main flavanols

Cocoa flavanols could ameliorate cardiovascular health in obese patients.

Rationale and design of a study exploring the efficacy of once-daily oral rivaroxaban (X-TRA) on the outcome of left atrial/left atrial appendage thrombus in nonvalvular atrial fibrillation or atrial flutter and a retrospective observational registry providing baseline data (CLOT-AF)

There are still many unresolved issues concerning patient outcomes and prognostic factors in patients with atrial fibrillation (AF) and left atrial/left atrial appendage (LA/LAA) thrombi. Rivaroxaban (Xarelto®), a potent and highly selective oral, direct factor Xa inhibitor, is a new therapeutic option in this setting. The planned study program will consist of a prospective interventional study (X-TRA) and a retrospective observational registry (CLOT-AF). The primary objective of the X-TRA study is to explore the efficacy of rivaroxaban in the treatment of LA/LAA thrombi in patients with nonvalvular AF or atrial flutter, scheduled to undergo cardioversion or AF ablation, in whom an LA/LAA thrombus has been found on transesophageal echocardiography (TEE) before the procedure. The primary end point is the complete LA/LAA thrombus resolution rate at 6 weeks of end of treatment confirmed by TEE. The secondary objectives are to describe categories of thrombus outcome in patients (resolved, reduced, unchanged, larger, or new) confirmed on TEE at the end of treatment (after 6 weeks of treatment), incidence of the composite of stroke and noncentral nervous system systemic embolism at the end of treatment and during follow-up, and incidence of all bleeding at the end of treatment and during follow-up. The objective of the CLOT-AF registry is to provide retrospective thrombus-related patient outcome data after standard-of-care anticoagulant treatment in patients with nonvalvular AF or atrial flutter, who have TEE-documented LA/LAA thrombi. The data will be used as a reference for the prospective X-TRA study. In conclusion, X-TRA and CLOT-AF will provide some answers to the many unresolved issues concerning patient outcomes and prognostic factors in patients with AF and LAA thrombi. Results from this study program would provide the first prospective interventional study (X-TRA) and a large international retrospective observational registry (CLOT-AF) on the prevalence and natural history of LA/LAA thrombi. Unique data on clot resolution with rivaroxaban in a prospective cohort would be obtained in X-TRA.