Evaluation of ADAMTS13 Activity and Inflammatory Markers in Deep Venous Thrombosis Patients

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 5246-5246
Author(s):  
Bruna de Moraes Mazetto ◽  
Fernanda A. Orsi ◽  
Aline Barnabé ◽  
Erich V de Paula ◽  
Joyce M Annichino-Bizzacchi
Keyword(s):  
Inflammatory Markers ◽  
Conflicts Of Interest ◽  
Adamts13 Activity ◽  
Vein Thrombosis ◽  
Outpatient Unit ◽  
Inflammatory Conditions ◽  
Significant Difference ◽  
Von Willebrand ◽  
D Dimer

Abstract Abstract 5246 BACKGROUND: The role of inflammation on the pathophysiology of arterial thrombosis has been extensively studied. However, the relationship between inflammation and deep vein thrombosis (DVT) is not completely understood. Conflicting reports have been published about the levels of proteins involved in the inflammatory response in the context of DVT. Changes in ADAMTS13 levels have been reported in other inflammatory conditions such as sepsis, and this protease could be involved in the interplay between hemostasis and inflammation. OBJECTIVE: To evaluate ADAMTS13 activity in DVT patients and its association with inflammatory markers (IL-6, IL-8, CRP, TNF-α), D-dimer and von Willebrand Factor (VWF) levels. METHODOLOGY: Thirty-eight DVT patients, from 6 months to five years after the diagnosis of DVT, followed at the outpatient unit of thrombotic diseases from University of Campinas and 38 healthy volunteers selected as controls were included in the study. ADAMTS13 activity was determined by the residual binding of VWF to collagen. VWF, IL-6, IL-8 and TNF-alpha levels were determined by ELISA, and D-dimer levels was determined by a turbidimetric method. RESULTS: In this study population DVT was triggered by transient risk factors, particularly the use of oral contraceptives. No patient presented renal, hepatic or malignant disease. Median ADAMTS13 activity was not statistically different between patients (median: 98.2%; range: 70–146) and controls (median: 96.1%; range: 66–117; p=0.35). IL-6 and TNF-alfa levels were also higher in patients (median: 1.0pg/mL and 2.3pg/mL) compared to controls (median: 0.64pg/mL and 1.7pg/mL, p=0,01 and p=0,009). In addition, VWF and D-dimer levels were also significantly higher in patients (all P<0.01). No significant difference could be demonstrated between IL-8 and CRP levels from patients and controls. No significant correlation between ADAMTS13 levels and other inflammatory markers could be demonstrated. VWF levels correlated significantly with IL-8 (r=-0.4635, p< 0.0001). CONCLUSIONS: This study reinforces the role of inflammation in the pathogenesis of DVT. The correlation of VWF and IL-8 supports the notion that IL-8 stimulates the secretion of VWF. The role of ADAMTS13 in the context of DVT is yet to be determined. Disclosures: No relevant conflicts of interest to declare.

Abstract 522: Activated FXI Regulates the Catalytic Activity of Adamts13 by Removing the CUB Domains

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Cristina Puy ◽  
Kathleen S Garland ◽  
Toshiaki Shirai ◽  
Stephanie E. Reitsma ◽  
Jevgenia Zilberman-Rudenko ◽  
...  
Keyword(s):  
Thrombus Formation ◽  
Adamts13 Activity ◽  
Binding Interaction ◽  
Vein Thrombosis ◽  
Cub Domain ◽  
A Cell ◽  
Von Willebrand ◽  
Deep Vein ◽  
Willebrand Factor

Background: ADAMTS13 cleaves and inactivates von Willebrand factor (VWF), which binds collagen, facilitating platelet adhesion under vascular injury. But is still uncertain how ADAMTS13 activity is regulated. Thrombin and plasmin have been shown to cleave ADAMTS13. Based on the fact that elevated levels of FXI is an independent risk factor for deep vein thrombosis and ischemic stroke, we hypothesize that FXIa inactivates ADAMTS13 leading to platelet aggregation and thrombus formation. Aim: To determine the functional role of inactivation of ADAMTS13 by FXIa. Methods and Results: Recombinant ADAMTS13 (250 nM) was incubated with FXIa (50 nM) for increasing times (0-3 hours) at 37 o C before being analyzed by western blot using an anti-ADAMTS13 antibody against the two CUB domains (C-terminal) or against the metalloproteinase (MET) domain (N-terminal). Our results show that FXIa caused the disappearance of the ADAMTS13 band (~200 kDa) and the appearance of a band at ~150 kDa when the samples were analyzed with the anti-MET antibody and a ~50 kDa band when the samples were analyzed with the anti-CUB antibody. The presence of aprotinin, which inhibits FXIa activity, blocked the degradation of ADAMTS13. Kallikrein or FXIIa were unable to cleave ADAMTS13. Using a cell surface immunoassay we observed that after incubation with FXIa, the detection of the CUB domain from ADAMTS13 was lost from endothelial cells surface. The incubation of ADAMTS13 with FXIa caused an increase in ADAMTS13 activity as measured by a fluorogenic substrate (FRETS). Conclusion: ADAMTS13 circulates in a closed conformation, which is maintained by a CUB-spacer domain binding interaction. ADAMTS13 becomes conformationally activated through interaction of its CUBs domains with VWF. Here we show that FXIa-mediated deletion of ADAMTS13-CUB domains enhances its capacity to cleave FRETS and blocks the interaction with VWF. Our results suggest that FXIa may limit ADAMTS13-mediated VWF inactivation.

scholarly journals Role of biomarkers in predicting prognosis of Coronavirus disease 2019 (COVID-19): A retrospective cross-sectional study: Perspective of a tertiary care hospital in India

2021 ◽  
Vol 11 (1) ◽  
pp. 081-090
Author(s):  
Arushi Mohan ◽  
Padmini SN ◽  
Brunda MS ◽  
Abhinaya Shekhar ◽  
Paul Matthew ◽  
...  
Keyword(s):  
Inflammatory Markers ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
C Reactive Protein ◽  
Oxygen Requirement ◽  
Cross Sectional ◽  
Reactive Protein ◽  
Significant Difference ◽  
D Dimer

Background: COVID-19 is a novel disease triggered by the SARS-CoV-2 virus, a beta coronavirus similar to MERS-CoV and SARS CoV. Inflammatory markers have a vital role in the pathogenesis of nCOVID 19; understanding the importance of these inflammatory markers in determining disease status is essential given the impact of the disease on healthcare. Thus, being able to triage cases with minimal tests is momentous to capture, which we have investigated as per our study guidelines of the role of inflammatory markers such as D-dimer, CRP (C - reactive protein), Ferritin, LDH (Lactate Dehydrogenase) in patients with COVID 19. In addition, limited data is available comparing the utility of these inflammatory markers to predict the following parameters as the need for ICU, oxygen support requirement, and duration of in-hospital stay, which can help guide the management protocol. Aim: This study aims to determine markers associated with poor prognosis in patients with Coronavirus disease 2019 (COVID-19). Objectives: 1) To assess the inflammatory markers that are routinely investigated in COVID- 19 patients. 2) To determine the most probable factor to estimate severity in COVID- 19 and thus predict prognosis. Methods: This is a retrospective cross-sectional observational study of patients who tested SARS COV 2 positive by RT PCR. The laboratory inflammatory markers, namely Lactate Dehydrogenase, C reactive protein, D-dimer, Ferritin, were assessed in the selected patients, and their clinical data and demographic details were taken into account. The parameters considered for contributing to the severity included the number of days of stay in the hospital, oxygen requirement, and ICU needs. Analyses relied upon analysis of variance for cross-sectional study design and a P< 0.05 statistical significance criterion. Results: There was a statistically significant difference found between oxygen requirement and D dimer (p<0.001), LDH (p= 0.002), and CRP (p= 0.024). There was a statistically significant difference found between admission to ICU and D Dimer (p= 0.001). Conclusion: A statistically significant association between the increasing D-dimer levels and all the outcome measures considered was found. The D-dimer, LDH, and CRP help predict oxygen requirement, and all the inflammatory markers can predict the number of days of stay in the hospital.

scholarly journals The prognostic role of inflammatory markers in COVID 19 patients – A retrospective analysis.

2021 ◽  
Author(s):  
Shivkumar Gopalakrishnan ◽  
sangeetha kandasamy ◽  
S.Malini ◽  
S.Peer Mohamed ◽  
k.velmurugan
Keyword(s):  
Inflammatory Markers ◽  
Severe Disease ◽  
Radiation Hazard ◽  
P Value ◽  
Binary Logistic Regression Analysis ◽  
Group Iii ◽  
Group I ◽  
Group Ii ◽  
D Dimer

Abstract Background. Approximately 5% of COVID-19 patients suffer near fatal disease. Clinical and radiologic features may predict severe disease albeit with limited specificity and radiation hazard. Laboratory biomarkers are eyed as simple, specific and point of care triage tools to optimize management decisions.This study aimed to study the role of inflammatory markers in prognosticating COVID-19 patients.Methodology. A hospital based retrospective study was conducted on COVID-19 adult inpatients classified into three groups as mild disease-recovered [Group I], severe disease-recovered [Group II] and dead [Group III]. Categorical outcomes were compared using Chi square test. Univariate binary logistic regression analysis was performed to test the association between the explanatory and outcome variables. Unadjusted OR along with 95% CI was calculated. The utility of lab parameters (Ferritin, LDH, D dimer, N/L ratio and PLT/L ratio) in predicting severity of COVID-19 was assessed by Receiver Operative Curve (ROC) analysis. P value < 0.05 was considered statistically significant.Results. The mean age was 49.32 +/- 17.1 years. Among study population, 378 were Group I, 66 Group II, and 56 Group III. Median levels of Ferritin among the 3 groups were 62ng/mL, 388.50 ng/mL and 1199.50 ng/mL. Median value of LDH were 95U/L, 720 and 982.50(p <0.001). D-dimer values of 3 groups were 23.20ng/mL, 104.30 ng/mL and 197.10 ng/mL (p <0.001). CRP done qualitatively was positive in 2 (0.53%), 30 (45.45%) and 53 (94.64%) of patients. The odds of patients suffering severe COVID-19 rose with rising values of ferritin, LDH and D-dimer [unadjusted OR 1.007, 1.004 &1.020]Conclusion. One time measurement of serum ferritin, LDH, D-dimer and CRP is promising to predict outcomes for COVID 19 inpatients. Single qualitative CRP was equally good but more cost effective than quantitative CRP. The most specific combination was NLR, Lymphocyte percentage and D-dimer levels done between 7th – 10th day of symptoms.

Investigating ADAMTS7 and ADAMTS12 levels in prediabetic and Type 2 diabetic patients

2021 ◽  
Author(s):  
Mercan Taştemur ◽  
Selvihan Beysel ◽  
Sema Hepşen ◽  
Sanem Öztekin ◽  
Erman Çakal ◽  
...  
Keyword(s):  
Inflammatory Markers ◽  
Diabetic Patients ◽  
Control Groups ◽  
Type 2 Diabetic Patients ◽  
Human Enzyme ◽  
Significant Difference ◽  
And Control ◽  
Type 2 Diabetic

Background: This study aims to investigate the role of ADAMTS7 and ADAMTS12 on atherosclerosis and inflammation in prediabetic and diabetic patients. Patients & methods: Serum ADAMTS7 and ADAMTS12 levels were compared with the atherosclerotic and inflammatory markers in diabetic (n = 65, female 30.9%, mean age = 53 years), prediabetic (n = 55, female 36.6%, mean age = 49 years) and control groups (n = 55, females 32.5%, mean age = 49 years). Serum ADAMTS levels were determined by a human enzyme-liked immunoassay. Results: In terms of ADAMTS7, there was no significant difference between diabetic, prediabetic and control groups (50.93, 44.34, 59.07, respectively; p > 0.05). ADAMTS12 is lower in diabetics (p < 0.05), whereas it is similar in prediabetics and controls (14.53, 20.76, 25.05, respectively; p > 0.05). ADAMTS7 and ADAMTS12 levels did not differ in diabetic nephropathy, retinopathy and neuropathy (p > 0.05). Conclusion: While ADAMTS12 was significantly lower in diabetics and prediabetics, ADAMTS7 and ADAMTS12 were not related to diabetic complications (nephropathy, retinopathy and neuropathy).

Role of D-Dimer Assay in Diagnosis of Deep Vein Thrombosis

2014 ◽  
Vol 9 (4) ◽  
pp. 187-194
Author(s):  
M.G. Vashist ◽  
S. Deswal ◽  
M. Verma ◽  
S. Kharb
Keyword(s):  
Deep Vein Thrombosis ◽  
Vein Thrombosis ◽  
Deep Vein ◽  
D Dimer

scholarly journals Increased plasma von Willebrand factor antigen levels but normal von Willebrand factor cleaving protease (ADAMTS13) activity in preeclampsia

2009 ◽  
Vol 101 (02) ◽  
pp. 305-311 ◽  
Author(s):  
János Rigó Jr ◽  
Tamás Bõze ◽  
Zoltán Derzsy ◽  
László Cervenak ◽  
Veronika Makó ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Von Willebrand Factor ◽  
Hellp Syndrome ◽  
Enzyme Linked Immunosorbent Assay ◽  
Adamts13 Activity ◽  
Elevated Liver Enzymes ◽  
Significant Difference ◽  
Low Platelet Count ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryThe activity of ADAMTS13, the von Willebrand factor (VWF) cleaving protease is low in several conditions, including HELLP (haemolysis, elevated liver enzymes, and low platelet count) syndrome. As HELLP syndrome develops in most cases on the basis of preeclampsia, our aim was to determine whether plasma ADAMTS13 activity is decreased in preeclampsia. Sixty-seven preeclamptic patients, 70 healthy pregnant women and 59 healthy non-pregnant women were involved in this case-control study. Plasma ADAMTS13 activity was determined with the FRETS-VWF73 assay, while VWF antigen (VWF:Ag) levels with an enzyme-linked immunosorbent assay. The multimeric pattern of VWF was analyzed by SDS-agarose gel electrophoresis. There was no significant difference in plasma ADAMTS13 activity between the preeclamptic and the healthy pregnant and non-pregnant groups (median [25–75 percentile]: 98.8 [76.5–112.8] %, 96.3 [85.6–116.2] % and 91.6 [78.5–104.4] %, respectively; p>0.05). However, plasma VWF:Ag levels were significantly higher in preeclamptic patients than in healthy pregnant and non-pregnant women (187.1 [145.6–243.1] % versus 129.3 [105.1–182.8] % and 70.0 [60.2–87.3] %, respectively; p<0.001). The multimeric pattern of VWF was normal in each group. Primiparas had lower plasma ADAMTS13 activity than multi-paras (92.6 [75.8–110.6] % versus 104.2 [92.1–120.8] %; p=0.011). No other relationship was found between clinical characteristics, laboratory parameters and plasma ADAMTS13 activity in either study group. In conclusion, plasma ADAMTS13 activity is normal in preeclampsia despite the increased VWF:Ag levels. However, further studies are needed to determine whether a decrease in plasma ADAMTS13 activity could predis-pose preeclamptic patients to develop HELLP syndrome.

ADAMTS13 In 4 Different VWF/VIII Concentrates and Its Impact on Therapy.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3677-3677
Author(s):  
Mirjeta Qorraj ◽  
Tanja Falter ◽  
Sarah Steinemann ◽  
Thomas Vigh ◽  
Inge Scharrer
Keyword(s):  
Von Willebrand Factor ◽  
Gel Electrophoresis ◽  
Conflicts Of Interest ◽  
Von Willebrand Disease ◽  
Relative Reduction ◽  
Hemorrhagic Diathesis ◽  
Adamts13 Activity ◽  
Kinetic Measurements ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Abstract 3677 Introduction: The hemostatic activity of von Willebrand Factor (VWF) is mainly controlled by the plasma metalloprotease ADAMTS13, which cleaves ultralarge VWF multimers. A qualitative or quantitative deficiency of VWF induces the most common hemorrhagic diathesis, the von Willebrand Disease (VWD). The current classification graduates the VWD in three major types. Depending on severity and the type of VWD the treatment with VWF/FVIII concentrates may by necessary. The commercially available VWF/FVIII concentrates differ in their multimer structure and furthermore also in their pharmacokinetics. We investigated commercial VWF concentrates with respect to their ADAMTS 13 activity and antigen levels with the newest available methods. Moreover, to detect a possible correlation, we analysed the VWF multimer structure of the concentrates. Methods: We analysed 4 human derived VWF/VIII-concentrates (over all 7charges) after reconstitution according to the manufacturer's instructions in different dilutions. Following methods were used: BCS Method according to Böhm detects the capacity of the concentrates for autoproteolysis. The VWF solutions were diluted with 5mol/l urea and then incubated for 14–16h at 37°C in low ionic TRIS buffer containing BaCl2 and different plasma samples: pool plasma; plasma from patients with TTP with neutralizing ADAMTS13 auto-antibodies; plasma from patients with TTP without auto-antibodies. The residual VWF:Ristocetin Cofactor (VWF:RCo) activity was subsequently measured using the BC von Willebrand Reagent from Dade Behring. ELISA Technozym®ADAMTS13 and Actifluor TM ADAMTS13 are based on the kinetic measurements of the activity with fluorescence resonance energy transfer (FRET). ADAMTS13 antigen was measured by use of the Technozym ELISA kit. SDS-Gel electrophoresis in 1% Agarose Gel was used to investigate the structure of VWF multimers. Results: The BCS Method according to Böhm is an indirect measurement for endogenous ADAMTS13 activity in the investigated concentrate. Important is the loss of the residual VWF:RCo in the concentrates in presence of TTP-plasma without antibodies and pool plasma compared to the residual VWF:RCo in presence of TTP-plasma with antibodies. All concentrates show some ADAMTS13 activity, however product 1 contains more ADAMTS13 than the other concentrates. The results of the two FRETS-assays correspond very well to the BCS-method results; in addition the assays detect directly the ADAMTS13 activity also in very low measurement range. In a dilution of 16U VWF per ml concentrate the ADAMTS13 activity in product 1 with 4.3% was the highest compared to product 2: 3.2%, product 3: 2.6% and product 4: 2%. The great variability of the test results in higher concentrations may be caused by interferences between some constituents of the concentrates and the analysis. In the same sample set and dilution the ADAMTS13 antigen values correlate very well with ADAMTS13 activity values. The SDS gel electrophoresis reveals the different VWF structure of product1; it has less large and ultralarge multimers. There could be a correlation to the relatively higher ADAMTS13 activity and antigen level. Conclusion: All the investigated VWF/VIII concentrates contain some ADAMTS13 activity and antigen. This was found especially by FRETs assay due to the high sensitivity. Because of the correlation between ADAMTS13 activity and modified VWF multimer structure we like to conclude that ADAMTS13 has influence on stability and therefore also on quality of the concentrates. This might have a therapeutic consequence especially for VWD type 2A. Type 2A is characterized by a relative reduction of intermediate and large VWF multimer. The multimeric abnormalities are commonly the result of in vivo proteolytic degradation of the von Willebrand factor caused by ADAMTS13. Disclosures: No relevant conflicts of interest to declare.

Investigation of Side Effects of Plasmaexchange In the Treatment of Thrombotic Thrombocytopenic Purpura

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4661-4661
Author(s):  
Sarah Steinemann ◽  
Tanja Falter ◽  
Mirjeta Qorraj ◽  
Thomas Vigh ◽  
Inge Scharrer
Keyword(s):  
Side Effects ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Side Effect ◽  
Conflicts Of Interest ◽  
Allergic Reactions ◽  
Adamts13 Activity ◽  
Plasma Therapy ◽  
Thrombocytopenic Purpura ◽  
Wide Range ◽  
Von Willebrand

Abstract Abstract 4661 Introduction: Thrombotic thrombocytopenic purpura (TTP) is characterized by thrombocytopenia, hemolytic anemia and microthrombi. A deficiency of the metalloprotease ADAMTS 13, which cleaves a Tys1605-Met1606 bond in the A2 subunit of von Willebrand factor (VWF), leads to formation of ultra large von Willebrand multimers (UL-VWF) and can cause platelet aggregation and mircovascular thrombosis. Treatment of choice is the substitution of plasma with plasmaexchange. There are two different plasma types available: Fresh Frozen Plasma (FFP) and solvent/detergent (s/d) treated plasma. This treatment may carry significant risks and side effects for the patients. Therefore we investigated the side effects of the therapy and furthermore the ADAMTS13 activity of the two plasma types. Methods: A questionnaire was send to 66 TTP patients of the Department of Hematology to evaluate different side effects of the therapy. 20 batches of FFP and 4 batches of s/d plasma of all blood groups were investigated on ADAMTS13 activity. The ADAMTS13 activity was detected with BCS-Method according to Böhm and two commercial FRET assays. Results: So far 34 patients were inquired about age, weight and suspected trigger situations that might have caused their TTP manifestation. The mean age of the patients was 34 years with a mean weight of 70kg. A previous infection caused TTP manifestation in 42% of the patients; drug therapy (22%) and pregnancy (17%) were other mentioned triggers. 94% of the patients suffered from an acquired TTP and only 6% had a hereditary TTP. The patients had 2.88 relapses and were treated with 16.27 plasmaexchanges. 56% had an additional therapy with Rituximab to achieve a faster remission of the disease. These patients needed less plasmaexchanges for recovery, which proofed to be significant at 2% level in a one sided t-test. Tingling (64.7%) and shivering (51%) were the most often mentioned side effects and simultaneously described as the strongest. Shivering was significantly correlated to tachycardia (p<0.01). Headaches were significantly correlated to hot flushes, tingling and collapse (p< 0.05). Side effects and allergic reactions occurred in the therapy with FFP as well as with s/d plasma. Another side effect was the complication that came along with infection of the venous access. Most patients had a central venous catheter (72%) and described infections and pruritus (60%), 50% of them mentioned this complication more than once. We found in usual FFP slightly higher ADAMTS13 activity levels (696.97 ng/ml) than in s/d virus inactivated plasma (643.86 ng/ml). The ADAMTS13 activity varied between the different assays (normal range: 666 ± 135ng/ml). Conclusion: Our investigation demonstrated that plasmaexchange therapy is still associated with a wide range of side effects. Side effects of plasmaexchange that were most frequently described by patients were tingling and shivering. Headaches also occurred in various cases. Patients suffered generally from more than one side effect at the same time during the treatment. Allergic reactions to the plasma therapy were mentioned by 65% of the patients. Disclosures: No relevant conflicts of interest to declare.

Increased Neutrophil Adhesive Properties In Patients with Venous Thromboembolism and Residual Vein Thrombosis and High D-Dimer Levels

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2301-2301
Author(s):  
kiara Cristina Senger Zapponi ◽  
Luis Fernando Bittar ◽  
Bruna m Mazetto ◽  
Fernanda Dutra Santiago-Bassora ◽  
Fernanda A. Orsi ◽  
...  
Keyword(s):  
Venous Thromboembolism ◽  
Venous Thrombosis ◽  
Recurrence Risk ◽  
Neutrophil Adhesion ◽  
Baseline Characteristic ◽  
Adherent Cells ◽  
Adhesive Properties ◽  
Vein Thrombosis ◽  
Significant Difference ◽  
D Dimer

Abstract Abstract 2301 Introduction: Venous Thromboembolism (VTE) is a multifactorial disease that affects 1:1000 individuals worldwide, with a recurrence rate of about 25% in 10 years. Although many risk factors for VTE are well defined, first presentation and recurrence depend, at least in part, on as yet unknown etiologic factors. Studies in animal models show a tight relation between inflammation and hemostasis, as well as the infiltration of neutrophils in the venous wall after the induction of venous thrombosis. Neutrophils also participate in different stages in the formation and resolution of venous thrombosis. Methods: In this study, we investigated the adhesive properties of neutrophils in VTE patients. We hypothesized that increased adhesive properties of these cells, either as an individual baseline characteristic or as an acquired alteration after a previous VTE episode, could be associated with the thrombotic process. The patient population consisted of 22 VTE patients (14F:8M; median age: 46.1 years) that had completed at least 6 months of oral anticoagulation. Twenty-two healthy volunteers matched to VTE patients by age, gender and ethnic background were used as controls. Neutrophil adhesion was measured by a static adhesion assay in triplicate. Peripheral blood was collected with heparin and neutrophils were separated on Histopaque® (Sigma-Aldrich, St. Louis, MO, USA). Isolated neutrophils (2.2×106 cells/ml) were allowed to adhere to fibronectin (FN)-coated 96-well plates (30 min, 37°C, 5%CO2). Non-adherent cells were then removed by washing and adherent cells calculated as the percentage of cells adhered, compared to a standard curve of known cell concentrations and using a colorimetric enzyme assay. Results are expressed as means ± standard error of mean (SEM) and were compared using the Mann-Whitney test. Results: Overall, adhesion of neutrophils from VTE patients (25.40% ±2.35) was not increased when compared to the control group (21.25%±1.20 p=0.2). However when only patients at a higher risk of recurrence (n=13) - here defined as the presence of elevated D-dimer (higher than 0.5mg/L) and residual vein thrombosis - were analyzed, a statistically significant increase in cell adhesion compared to matched controls was observed (26.70%±2.08 and 21.36%±1.26, respectively, p = 0.04). When these patients (higher recurrence risk; n=13) were compared to the remaining VTE patients (standard recurrence risk, n=9), a non significant increase in neutrophil adhesion was observed (26.70%±2.08 vs 23.51%±5.03 respectively, p=0.1). Conclusions: We demonstrate that neutrophil adhesion is increased in patients with VTE with characteristics associated with increased recurrence risk. In addition, we also observed a non-significant difference in neutrophil adhesion in these patients compared to other VTE patients. Our results suggest that the increased adhesive properties of neutrophils in VTE patients could play a role in the exacerbation of inflammation, and in the pathophysiology of VTE. Further studies are warranted to study whether neutrophil adhesiveness could be used as a biomarker of VTE recurrence. Disclosures: No relevant conflicts of interest to declare.

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