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| 2. |
- Cedervall, Jessica, et al.
(författare)
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HRG regulates tumor progression, epithelial to mesenchymal transition and metastasis via platelet-induced signaling in the pre-tumorigenic microenvironment
- 2013
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Ingår i: Angiogenesis. - : Springer Science and Business Media LLC. - 0969-6970 .- 1573-7209. ; 16:4, s. 889-902
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Tidskriftsartikel (refereegranskat)abstract
- Mice lacking histidine-rich glycoprotein (HRG) display an accelerated angiogenic switch and larger tumors-a phenotype caused by enhanced platelet activation in the HRG-deficient mice. Here we show that platelets induce molecular changes in the pre-tumorigenic environment in HRG-deficient mice, promoting cell survival, angiogenesis and epithelial-to-mesenchymal transition (EMT) and that these effects involved signaling via TBK1, Akt2 and PDGFR beta. These early events subsequently translate into an enhanced rate of spontaneous metastasis to distant organs in mice lacking HRG. Later in tumor development characteristic features of pathological angiogenesis, such as decreased perfusion and pericyte coverage, are more pronounced in HRG-deficient mice. At this stage, platelets are essential to support the larger tumor volumes formed in mice lacking HRG by keeping their tumor vasculature sufficiently functional. We conclude that HRG-deficiency promotes tumor progression via enhanced platelet activity and that platelets play a dual role in this process. During early stages of transformation, activated platelets promote tumor cell survival, the angiogenic switch and invasiveness. In the more progressed tumor, platelets support the enhanced pathological angiogenesis and hence increased tumor growth seen in the absence of HRG. Altogether, our findings strengthen the notion of HRG as a potent tumor suppressor, with capacity to attenuate the angiogenic switch, tumor growth, EMT and subsequent metastatic spread, by regulating platelet activity.
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| 3. |
- Christersson, Christina, et al.
(författare)
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Evaluation of microparticles in whole blood by multicolour flow cytometry assay
- 2013
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 73:3, s. 229-239
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveTo develop and evaluate a multicolour flow cytometry method for analysis of microparticles (MPs) in fresh whole blood without any centrifugation steps or freezing/thawing procedure. Materials and methodsFlow cytometry was performed using a FC500 MPL cytometer. The compensation in the protocol was performed based on the platelet population. Polystyrene microspheres 0.50–1.27 μm were used for size position, and the MP gate was set as particles 0.5–1.0 μm. Whole blood was incubated with annexin V and antibodies to tissue factor (TF), platelets (CD41 and CD62P), monocyte (CD14) and endothelial cells (CD144). For comparison, MPs from platelet free supernatant was used. The TF activity was evaluated by Calibrated Automated Thrombogram. ResultsAnnexin V was used to distinguish true events from background noise. For standardization, each analysis included 10,000 events in the gate of platelets. There were 622(462–1001) MPannV+/10,000 platelets and of these, 66 (49–82)/10,000 platelets expressed TF. After correction for the individual platelet counts, the amount of circulating MPannV+ was 17.1 (12.1–24.9) × 109/L in whole blood, and of these, 10% (6–12%) expressed TF. The majority of the MPs expressed CD41, and 5.6% (2.2–6.9%) of these co-expressed TF. The amount of CD41 + MPannV+ tended to correlate to the TF activity in whole blood. There was no correlation between the MPannV+ in whole blood and MPs derived from platelet free supernatant. Patients with pulmonary arterial hypertension and stable coronary artery disease had increased concentrations of CD41 + MPannV+ in whole blood.ConclusionThis multicolour flow cytometry assay in whole blood mimics the in vivo situation by avoiding several procedure steps interfering with the MP count. By standardized quantification of MPs a reference interval of MPs can be created.
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| 5. |
- Christersson, Christina, et al.
(författare)
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The Influence of Direct Thrombin Inhibitors on the Formation of Platelet-leukocyte Aggregates and Tissue Factor Expression
- 2010
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Ingår i: Thrombosis Research. - : Elsevier BV. - 0049-3848 .- 1879-2472. ; 126:4, s. E327-E333
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: High concentrations of platelet-monocyte aggregates (PMAs) have been found in patients with myocardial infarction (MI). Oral direct thrombin inhibitors (DTIs) are under evaluation as long-term antithrombotic treatment. The aim was to evaluate whether DTIs affect the formation of platelet-leukocyte aggregates, TF expression and procoagulant microparticles (MPs). Material and Methods: DTIs were added to an experimental whole blood model before platelet activation with thrombin or ADP. The concentrations of PMAs, platelet-granulocyte aggregates (PGAs), the amount of platelets bound per leukocyte and MPs were investigated by flow cytometry. TF mRNA and activity were recorded in all settings. TF activity was evaluated in a MI population treated with or without an oral DTI. Results: In vitro, thrombin and ADP increased the formation of PMAs and PGAs as well as TF mRNA expression. DTIs reduced the amount platelets bound to monocytes (p = 0.02) and to granulocytes (p = 0.001) upon thrombin stimulation together with a reduction of TF mRNA. In contrast, the ADP-induced formation of PMAs, PGAs and TF mRNA was not affected by the DTIs. Both thrombin and ADP stimulation increased the amount of TF-expressing MPs, which was effectively inhibited by the DTIs (p = 0.02-0.002). In the MI population, the DTI reduced the TF activity (p<0.001). Conclusion: DTIs modulate the formation of PMAs, PGAs and the TF production therein. Together with a reduction of procoagulant MPs, these results may contribute to the clinical benefit found of oral DTIs. Targeting different mechanisms in platelet and coagulation activation may be of importance due to the lack of effect of DTIs on ADP-induced platelet-leukocyte aggregates and TF production.
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| 6. |
- Christersson, Christina, et al.
(författare)
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Treatment with an Oral Direct Thrombin Inhibitor Decreases Platelet Activity but Increases Markers of Inflammation in Patients with Myocardial Infarction.
- 2011
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 270:3, s. 215-223
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Tidskriftsartikel (refereegranskat)abstract
- Background: Thrombin has a role not only in the coagulation process but also in inflammatory responses. Oral direct thrombin inhibitors (DTIs) are currently being evaluated in patients with thromboembolic diseases. Objectives: To investigate whether an oral DTI affects markers for platelet and inflammatory activity after myocardial infarction (MI). Methods: A total of 518 patients with MI were randomly assigned to ximelagatran treatment (four different dose groups) in combination with aspirin, or aspirin alone for 6 months. The levels of soluble (s) P-selectin, soluble tissue factor, C-reactive protein (CRP), interleukin (IL)-10 and IL-18 were analysed in serial blood samples.Results: sP-selectin concentration increased after 1 week and persisted at an elevated level for 6 months in all study groups (p<0.001). In the two highest ximelagatran dose groups, there was a reduced increase in sP-selectin compared to treatment with lower doses of ximelagatran and aspirin alone (p=0.01 and p=0.002, respectively). IL-18 levels did not change in the aspirin alone treatment group. By contrast, there was an elevation in IL-18 level in the lower and higher ximelagatran dose groups after 6 months (p=0.006 and p<0.001, respectively). Ximelagatran increased IL-10 levels (p=0.002) and reduced the decrease in CRP levels after 6 months compared to treatment with aspirin alone (p=0.002).Conclusion: A persistent elevation of platelet activity is found in patients with a recent MI after the cessation of acute antithrombotic treatment, and the addition of an oral DTI at higher doses decreases the activity. By contrast, long-term treatment with a DTI increases the levels of several markers of inflammation. Further studies with prolonged exposure of oral DTIs are needed for evaluation of the effect on inflammatory processes and to determine whether these agents influence clinical outcomes.
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| 7. |
- Darmanis, Spyros, et al.
(författare)
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ProteinSeq : high-performance proteomic analyses by proximity ligation and next generation sequencing
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:9, s. e25583-
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Tidskriftsartikel (refereegranskat)abstract
- Despite intense interest, methods that provide enhanced sensitivity and specificity in parallel measurements of candidate protein biomarkers in numerous samples have been lacking. We present herein a multiplex proximity ligation assay with readout via realtime PCR or DNA sequencing (ProteinSeq). We demonstrate improved sensitivity over conventional sandwich assays for simultaneous analysis of sets of 35 proteins in 5 μl of blood plasma. Importantly, we observe a minimal tendency to increased background with multiplexing, compared to a sandwich assay, suggesting that higher levels of multiplexing are possible. We used ProteinSeq to analyze proteins in plasma samples from cardiovascular disease (CVD) patient cohorts and matched controls. Three proteins, namely P-selectin, Cystatin-B and Kallikrein-6, were identified as putative diagnostic biomarkers for CVD. The latter two have not been previously reported in the literature and their potential roles must be validated in larger patient cohorts. We conclude that ProteinSeq is promising for screening large numbers of proteins and samples while the technology can provide a much-needed platform for validation of diagnostic markers in biobank samples and in clinical use.
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| 8. |
- Darmanis, Spyros, et al.
(författare)
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Sensitive plasma protein analysis by microparticle-based proximity ligation assays
- 2010
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Ingår i: Molecular & Cellular Proteomics. - 1535-9476 .- 1535-9484. ; 9:2, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- Detection of proteins released in the bloodstream from tissues damaged by disease can promote early detection of pathological conditions, differential diagnostics, and follow-up of therapy. Despite these prospects and a plethora of candidate biomarkers, efforts in recent years to establish new protein diagnostic assays have met with limited success. One important limiting factor has been the challenge of detecting proteins present at trace levels in complex bodily fluids. To achieve robust, sensitive, and specific detection, we have developed a microparticle-based solid-phase proximity ligation assay, dependent on simultaneous recognition of target proteins by three antibody molecules for added specificity. After capture on a microparticle, solid-phase pairs of proximity probes are added followed by washes, enabling detection and identification of rare protein molecules in blood while consuming small amounts of sample. We demonstrate that single polyclonal antibody preparations raised against target proteins of interest can be readily used to establish assays where detection depends on target recognition by three individual antibody molecules, recognizing separate epitopes. The assay was compared with state-of-the-art sandwich ELISAs for detection of vascular endothelial growth factor, interleukin-8 and interleukin-6, and it was found to be superior both with regard to dynamic range and minimal numbers of molecules detected. Furthermore, the assays exhibited excellent performance in undiluted plasma and serum as well as in whole blood, producing comparable results for nine different antigens. We thus show that solid-phase proximity ligation assay is suitable for validation of a variety of protein biomarkers over broad dynamic ranges in clinical samples.
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| 9. |
- De Caterina, R, et al.
(författare)
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General mechanisms of coagulation and targets of anticoagulants (Section I) : Position Paper of the ESC Working Group on Thrombosis - Task Force on Anticoagulants in Heart Disease
- 2013
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 109:4, s. 569-579
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Tidskriftsartikel (refereegranskat)abstract
- Contrary to previous models based on plasma, coagulation processes are currently believed to be mostly cell surface-based, including three overlapping phases: initiation, when tissue factor-expressing cells and microparticles are exposed to plasma; amplification, whereby small amounts of thrombin induce platelet activation and aggregation, and promote activation of factors (F)V, FVIII and FXI on platelet surfaces; and propagation, in which the Xase (tenase) and prothrombinase complexes are formed, producing a burst of thrombin and the cleavage of fibrinogen to fibrin. Thrombin exerts a number of additional biological actions, including platelet activation, amplification and self-inhibition of coagulation, clot stabilisation and anti-fibrinolysis, in processes occurring in the proximity of vessel injury, tightly regulated by a series of inhibitory mechanisms. "Classical" anticoagulants, including heparin and vitamin K antagonists, typically target multiple coagulation steps. A number of new anticoagulants, already developed or under development, target specific steps in the process, inhibiting a single coagulation factor or mimicking natural coagulation inhibitors.
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| 10. |
- De Caterina, Raffaele, et al.
(författare)
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New Oral Anticoagulants in Atrial Fibrillation and Acute Coronary Syndromes : ESC Working Group on Thrombosis - Task Force on Anticoagulants in Heart Disease Position Paper
- 2012
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Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 59:16, s. 1413-1425
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Forskningsöversikt (refereegranskat)abstract
- Until recently, vitamin K antagonists were the only available oral anticoagulants, but with numerous limitations that prompted the introduction of new oral anticoagulants targeting the single coagulation enzymes thrombin (dabigatran) or factor Xa (apixaban, rivaroxaban, and edoxaban) and given in fixed doses without coagulation monitoring. Here we review the pharmacology and the results of clinical trials with these new agents in stroke prevention in atrial fibrillation and secondary prevention after acute coronary syndromes, providing perspectives on their future incorporation into clinical practice. In phase III trials in atrial fibrillation, compared with warfarin, dabigatran etexilate 150 mg B.I.D. reduced the rates of stroke/systemic embolism without any difference in major bleeding; dabigatran etexilate 110 mg B.I.D. had similar efficacy with decreased bleeding; apixaban 5 mg B.I.D. reduced stroke, systemic embolism, and mortality as well as major bleeding; and rivaroxaban 20 mg Q.D. was noninferior to warfarin for stroke and systemic embolism without a difference in major bleeding. All these agents reduced intracranial hemorrhage. Edoxaban is currently being evaluated in a further large phase III trial. Apixaban and rivaroxaban were evaluated in phase III trials for prevention of recurrent ischemia in patients with acute coronary syndromes who were mostly receiving dual antiplatelet therapy, with conflicting results on efficacy but consistent results for increased major bleeding. Overall, the new oral anticoagulants are poised to replace vitamin K antagonists for many patients with atrial fibrillation and may have a role after acute coronary syndromes. Although convenient to administer and manage, they present challenges that need to be addressed.
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