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- Christersson, Christina, 1966-
(författare)
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Regulation of Tissue Factor and Coagulation Activity : Translation Studies with Focus on Platelet-Monocyte Aggregates and Patients with Acute Coronary Syndrome
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Myocardial infarction (MI) is often caused by a disruption of an atherosclerotic plaque with activation of coagulation, platelets and inflammation. The aims were; to investigate whether the oral direct thrombin inhibitor, ximelagatran affected markers for coagulation, platelet and inflammation in a patient cohort with recent MI and if the coagulation markers could identify patients with increased risk of new ischemic events; to evaluate some of the mechanisms involved in formation of platelet-monocyte aggregates (PMAs). In a biomarker substudy patients with recent MI were randomized to 24-60 mg of ximelagatran or placebo for six months. There was a persistent dose-independent reduction of coagulation markers (F1+2, D-dimer) by ximelagatran treatment. 60 % reduced their D-dimer levels after one week and that group had less ischemic events during treatment. There was an early increase of the platelet activation marker and ximelagatran in higher doses attenuated these increased levels. Both in vivo and in vitro the direct thrombin inhibitor diminished procoagulant activity and tissue factor (TF) presenting microparticles. In contrast, the inflammatory markers increased after six months of ximelagatran treatment. The PMA-levels were elevated for long-term after MI. In vitro thrombin inhibition diminished formation of PMAs. Formation of PMAs in stimulated whole blood was P-selectin dependent and induced TF expression through phosphorylation of the Src-family member Lyn in monocytes. Addition of an oral direct thrombin inhibitor reduces coagulation and platelet activation markers for long-term after a MI together with reduced procoagulant activity which may contribute to the clinical benefit of the drug. Early reduction of D-dimer levels seems to be suitable to identify patients with reduced risk of new ischemic events independent of antithrombotic treatment. Circulating PMAs persist after a MI connecting coagulation to inflammation. Within these aggregates P-selectin induces TF, the main initiator of coagulation, partly through phosphorylation of Lyn.
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- Darmanis, Spyros, et al.
(författare)
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Multiplexed solid-phase proximity ligation assays: Highly specific and parallel protein measurements with DNA sequencing readout
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Identification and validation of protein biomarkers is a very important step towards the understanding of the underlying mechanisms of disease, early diagnosis and efficient patient treatment. To carry out this task, methods are needed that would allow us to mine the proteome with sufficient sensitivity and specificity in large sets of samples. We present herein the development of a Multiplexed Proximity Ligation Assay (MultiPLAy), to facilitate efficient protein profiling in a parallel, sensitive and specific manner. We showed that for the simultaneous analysis of 35 proteins MultiPLAy exhibited an improved sensitivity over conventional sandwich assays as well as a smaller susceptibility to background signal increase in the transition from singleplex to multiplex. We used MultiPLAy to identify putative biomarkers in two separate sample cohorts of colorectal cancer (CRC) and cardiovascular disease (CVD) and with the use a novel multivariate analysis approach were able to identify new, as well as already known diagnostic biomarkers. Furthermore we were able to combine MultiPLAy with the use of next-generation sequencing allowing for the first time digital recording of protein profiles in blood. We demonstrated good reproducibility of MultiPLAy coupled to next-generation sequencing, as well as a satisfactory correlation to standard real-time PCR readout. We conclude that MultiPLAy has great potential as a basis for highly multiplexed protein detection assays that can be utilized for the identification of large numbers of proteins or protein variants. This will allow extensive validation of protein expression patterns in biobanked samples and in prospective studies, and can provide a much-needed platform for efficient validation of diagnostic markers for clinical use.
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- Edén, Desireé
(författare)
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Tissue Factor regulation, signaling and functions beyond coagulation with a focus on diabetes
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Tissue factor (TF) is a 47 kDa transmembrane glycoprotein best known for initiating the coagulation cascade upon binding of its ligand FVIIa. Apart from its physiological role in coagulation, TF and TF/FVIIa signaling has proved to be involved in diseases such as diabetes, cancer and cardiovascular diseases. Biological functions coupled to TF/FVIIa signaling include diet-induced obesity, apoptosis, angiogenesis and migration.Aim: The aim of this thesis was to investigate the role of TF/FVIIa in cells of importance in diabetes, to further investigate the mechanism behind TF/FVIIa anti-apoptotic signaling in cancer cells and lastly to examine the regulation of TF expression in monocytes by micro RNAs (miRNA).Results: In paper I we found that TF/FVIIa signaling augments cytokine-induced beta cell death and impairs glucose stimulated insulin secretion from human pancreatic islets. In paper II the relevance of TF/FVIIa in isolated human primary adipocytes was investigated. Adipocytes are a target cell for insulin and diabetics typically have increased lipolysis and impaired glucose uptake. No evidence was found for a role of TF/FVIIa in lipolysis or glucose uptake in adipocytes. However, adipocytes were found to express TF and FVII. The FVII produced was sufficient to initiate coagulation in the adipocytes. In paper III an anti-apoptotic TF/FVIIa induced signaling pathway in prostate and breast cancer cells was investigated in depth. Previous research has shown that TF/FVIIa signaling results in transactivation of insulin-like growth factor 1 receptor (IGF-1R) leading to subsequent protection from apoptosis induced by TNF-related apoptosis inducing ligand (TRAIL). The current results propose a mechanism where IGF-1R transactivation by TF/FVIIa is dependent on integrin β1 (ITGβ1) signaling. TF/FVIIa/ ITGβ1 signaling was found to result in phosphorylation of src and subsequent phosphorylation of caveolin 1 (Cav1). Once phosphorylated, the inhibitory effect of Cav1 on IGF-1R is cancelled, resulting in IGF-1R activation. In paper IV the role of miRNA regulation of TF expression in monocytic cells was investigated. The miRNA miR-223-3p was identified to be differentially expressed in U937 cells undergoing differentiation to a more monocyte-like phenotype and an anti-parallel correlation between TF and miR-223-3p expression in monocytes was proved. Hence, miR-223-3p regulates the inducible expression of TF in monocytes.Conclusions: The work in this thesis furthers the knowledge of molecular mechanisms behind TF regulation and TF/FVIIa signaling and some functional consequences as well as their biological relevance in diabetes.
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