Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Inge Pareyn is active.

Publication


Featured researches published by Inge Pareyn.


Journal of Biological Chemistry | 2006

Shielding of the A1 domain by the D'D3 domains of von Willebrand factor modulates its interaction with platelet glycoprotein Ib-IX-V

Hans Ulrichts; Miklós Udvardy; Peter J. Lenting; Inge Pareyn; Nele Vandeputte; Karen Vanhoorelbeke; Hans Deckmyn

Soluble von Willebrand factor (VWF) has a low affinity for platelet glycoprotein (GP) Ibα and needs immobilization and/or high shear stress to enable binding of its A1 domain to the receptor. The previously described anti-VWF monoclonal antibody 1C1E7 enhances VWF/GPIbα binding and recognizes an epitope in the amino acids 764–1035 region in the N-terminal D′D3 domains. In this study we demonstrated that the D′D3 region negatively modulates the VWF/GPIb-IX-V interaction; (i) deletion of the D′D3 region in VWF augmented binding to GPIbα, suggesting an inhibitory role for this region, (ii) the isolated D′D3 region inhibited the GPIbα interaction of a VWF deletion mutant lacking this region, indicating that intramolecular interactions limit the accessibility of the A1 domain, (iii) using a panel of anti-VWF monoclonal antibodies, we next showed that the D′D3 region is in close proximity with the A1 domain in soluble VWF but not when VWF was immobilized; (iv) destroying the epitope of 1C1E7 resulted in a mutant VWF with an increased affinity for GPIbα. Our results support a model of domain translocation in VWF that allows interaction with GPIbα. The suggested shielding interaction of the A1 domain by the D′D3 region then becomes disrupted by VWF immobilization.


Journal of Thrombosis and Haemostasis | 2006

ADAMTS-13 plasma level determination uncovers antigen absence in acquired thrombotic thrombocytopenic purpura and ethnic differences.

Hendrik B. Feys; Fang Liu; Dong Nz; Inge Pareyn; Stefaan Vauterin; Nele Vandeputte; Wim Noppe; Changgeng Ruan; Hans Deckmyn; Karen Vanhoorelbeke

Summary.  Background: The recently discovered plasma enzyme ADAMTS‐13 cleaves the A2‐domain of von Willebrand factor (VWF). A defective cleaving protease results in unusually large VWF multimers, which cause thrombotic thrombocytopenic purpura (TTP). Aim: Analysis of the ADAMTS‐13 antigen levels in TTP patients compared with normal donors. Methods: An antigen ELISA test was built, based on high affinity anti‐ADAMTS‐13 monoclonal antibodies, which were generated using genetic immunization. Results: Specificity of the ADAMTS‐13 antigen test was confirmed, as (i) plasma from a patient with acquired TTP but presenting without inhibitor did not contain antigen and (ii) the binding of recombinant ADAMTS‐13 was inhibited by increasing amounts of normal plasma. The assay is sensitive as it can detect antigen levels as low as 1.6% of normal. The concentration in normal pooled human plasma was determined (1.03 ± 0.15 μg mL−1) and arbitrarily set to 1 U mL−1. The antigen levels in congenital TTP samples (34 ± 21 mU mL−1, n = 2), as well as in samples from patients with acquired TTP (231 ± 287 mU mL−1, n = 11), were clearly reduced when compared with normal Caucasian donors (951 ± 206 mU mL−1, n = 16). Remarkably, normal Chinese donors have a significantly lower antigen titer (601 ± 129 mU mL−1, n = 15), when compared with normal Caucasians. Conclusions: Our results show that acquired TTP patients suffer mainly from ADAMTS‐13 antigen depletion, thereby indicating the importance of ADAMTS‐13 antigen determination in diagnosis and patient follow‐up.


Blood | 2010

Thrombotic thrombocytopenic purpura directly linked with ADAMTS13 inhibition in the baboon ( Papio ursinus )

Hendrik B. Feys; Jan Roodt; Nele Vandeputte; Inge Pareyn; Seb Lamprecht; Walter J. Janse van Rensburg; Patricia J. Anderson; Ulrich Budde; Vernon J. Louw; Philip N. Badenhorst; Hans Deckmyn; Karen Vanhoorelbeke

Thrombotic thrombocytopenic purpura (TTP) is the prototypical microangiopathy characterized by disseminated microthromboses, hemolytic anemia, and ultimately organ dysfunction. A link with deficiency of the von Willebrand factor-cleaving protease (ADAMTS13) has been demonstrated, but additional genetic and/or environmental triggers are thought to be required to incite acute illness. Here we report that 4 days of ADAMTS13 functional inhibition is sufficient to induce TTP in the baboon (Papio ursinus), in the absence of inciting triggers because injections with an inhibitory monoclonal antibody (mAb) consistently (n = 6) induced severe thrombocytopenia (< 12 × 10(9)/L), microangiopathic hemolytic anemia, and a rapid rise in serum lactate dehydrogenase. Immunohistochemical staining revealed the characteristic disseminated platelet- and von Willebrand factor-rich thrombi in kidney, heart, brain, and spleen but not lungs. Prolonged inhibition (14 days, n = 1) caused myocardial ischemic damage and asplenia but not death. Control animals (n = 5) receiving equal doses of a noninhibitory anti-ADAMTS13 mAb remained unaffected. Our results provide evidence for a direct link between TTP and ADAMTS13 inhibition and for a mild disease onset. Furthermore, we present a reliable animal model of this disease as an opportunity for the development and validation of novel treatment strategies.


Arteriosclerosis, Thrombosis, and Vascular Biology | 2008

Restoration of Plasma von Willebrand Factor Deficiency Is Sufficient to Correct Thrombus Formation After Gene Therapy for Severe von Willebrand Disease

Simon F. De Meyer; Nele Vandeputte; Inge Pareyn; Inge Petrus; Peter J. Lenting; Marinee Chuah; Thierry Vandendriessche; Hans Deckmyn; Karen Vanhoorelbeke

Objective—Gene therapy for severe von Willebrand disease (vWD) seems an interesting treatment alternative with long-term therapeutic potential. We investigated the feasibility of targeting the liver for ectopic expression of physiologically active von Willebrand factor (vWF). Methods and Results—The capacity of transgene-encoded murine vWF to restore vWF function was studied in a mouse model of severe vWD after liver-specific gene transfer by hydrodynamic injection. By using a hepatocyte-specific &agr;1 antitrypsin promoter, a considerably higher and longer-lasting vWF expression was obtained when compared with a cytomegalovirus promoter, reaching maximum vWF plasma levels that are 10±1 times higher than the wild-type level. Liver-expressed vWF showed the full range of multimers, including the high molecular weight multimers, and restored factor VIII plasma levels, consistent with correction of the bleeding time 3 but not 7 days after gene transfer. Importantly, transgene encoded plasma vWF restored proper platelet adhesion and aggregation in a FeCl3 induced thrombosis model. Conclusions—High ectopic expression of transgene encoded plasma vWF can be obtained after gene transfer to the liver. Liver-expressed vWF was fully multimerized and able to restore proper platelet plug formation in severe vWD. The liver therefore seems an attractive target for gene therapy for severe vWD.


Journal of Biological Chemistry | 2005

Two functional active conformations of the integrin α2β1, depending on activation condition and cell type

Gerlinde R. Van de Walle; Karen Vanhoorelbeke; Zsuzsa Majer; Eszter Illyés; Johan Baert; Inge Pareyn; Hans Deckmyn

For several integrins, the existence of multiple conformational states has been studied intensively. For the integrin α2β1, a major collagen receptor on platelets and other cell types, however, no such experimental data were available thus far. Recently, our group has developed a monoclonal antibody IAC-1 sensitive to the molecular conformation of α2β1 because it only binds to the activated state of α2β1 on platelets, induced upon inside-out signaling. By investigating IAC-1 binding in combination with collagen binding after inside-out stimulation and outside manipulation, we demonstrated the existence of three different conformations of α2β1 on platelets and Chinese hamster ovary cells as follows: (i) a nonactivated, resting state with no collagen nor IAC-1 binding; (ii) an intermediate state, induced by outside manipulation, with collagen but no IAC-1 binding; and (iii) a fully activated state, induced after inside-out stimulation, with both collagen and IAC-1 binding. Moreover, these different conformational states of α2β1 are dependent on the cell type where α2β1 is expressed, as IAC-1 binding to peripheral blood mononuclear cells and Jurkat cells could also be induced by outside manipulation, in contrast to platelets and α2β1-expressing Chinese hamster ovary cells. Finally, we revealed a functional relevance for these different conformational states because the conformation of α2β1, induced after outside manipulation, resulted in significantly more cell spreading on coated collagen compared with nonactivated or inside-out stimulated cells.


Blood | 2012

Inhibition of von Willebrand factor-platelet glycoprotein Ib interaction prevents and reverses symptoms of acute acquired thrombotic thrombocytopenic purpura in baboons

Hendrik B. Feys; Jan Roodt; Nele Vandeputte; Inge Pareyn; Harald Mottl; Sam Hou; Seb Lamprecht; Walter J. Janse van Rensburg; Hans Deckmyn; Karen Vanhoorelbeke

The pathophysiology of thrombotic thrombocytopenic purpura (TTP) can be explained by the absence of active ADAMTS13, leading to ultra-large von Willebrand factor (UL-VWF) multimers spontaneously interacting with platelets. Preventing the formation of UL-VWF-platelet aggregates therefore is an attractive new treatment strategy. Here, we demonstrate that simultaneous administration of the inhibitory anti-VWF monoclonal antibody GBR600 and the inhibitory anti-ADAMTS13 antibody 3H9 to baboons (prevention group) precluded TTP onset as severe thrombocytopenia and hemolytic anemia were absent in these animals. In addition, partial VWF inhibition was not enough to prevent thrombocytopenia, demonstrating the specificity of this therapeutic strategy. GBR600 treatment of baboons during acute TTP (treatment group) resulted in a rapid recovery of severe thrombocytopenia similar to the platelet count increases observed in TTP patients treated by plasma exchange. Baboons in the control group only injected with 3H9 developed early stages of TTP as previously described. Hence, inhibiting VWF-GPIb interactions is an effective way to prevent and treat the early symptoms of acquired TTP in baboons.


Thrombosis and Haemostasis | 2006

Rational humanization of the powerful antithrombotic anti-GPIbα antibody: 6B4

Alexandre Fontayne; Karen Vanhoorelbeke; Inge Pareyn; Isabel Van Rompaey; Muriel Meiring; Seb Lamprecht; Jan Roodt; Johan Desmet; Hans Deckmyn

Fab-fragments of the monoclonal antibody 6B4, raised against human glycoprotein Ibα (GPIbα), have a powerful antithrombotic effect in baboons by blocking the GPIbα binding site for von Willebrand factor (VWF), without significant prolongation of the skin bleeding time. In order to bring this antibody to the clinic,we here humanized for the first time an anti-human GPIbα by variable-domain resurfacing guided by computer modeling. First, the genes coding for the variable regions of the heavy and light chains of 6B4 were cloned and sequenced. Based on this, a three-dimensional structure of the Fv-fragment was constructed by using homology-based modeling, and with this and comparison with antibodies with known structure,“murine” putative immunogenic residues which are exposed, were changed for “human-like” residues. The humanized Fab-fragment, h6B4-Fab, was constructed in the pKaneo vector system, expressed and purified and showed in vitro an unaltered, even slightly higher binding affinity for its antigen than the murine form as determined by different ELISA set-ups and surface plasmon resonance. Finally, injection of doses of 0.1 to 1.5 mg/kg of h6B4-Fab in baboons showed that both pharmacokinetics and ex-vivo bio-activity of the molecule were to a large extent preserved. In conclusion,the method used here to humanize 6B4 by resurfacing resulted in a fully active derivative, which is now ready for further development.


Journal of Thrombosis and Haemostasis | 2010

The distal carboxyterminal domains of murine ADAMTS13 influence proteolysis of platelet-decorated VWF strings in vivo

B. De Maeyer; S. F. De Meyer; Hendrik B. Feys; Inge Pareyn; Nele Vandeputte; Hans Deckmyn; Karen Vanhoorelbeke

Summary.  Background: The multidomain metalloprotease ADAMTS13 regulates the size of von Willebrand factor (VWF) multimers upon their release from endothelial cells. How the different domains in ADAMTS13 control VWF proteolysis in vivo remains largely unidentified. Methods: Seven C‐terminally truncated murine ADAMTS13 (mADAMTS13) mutants were constructed and characterized in vitro. Their ability to cleave VWF strings in vivo was studied in the ADAMTS13−/− mouse. Results: Murine MDTCS (devoid of T2‐8 and CUB domains) retained full enzyme activity in vitro towards FRETS‐VWF73 and the C‐terminal T6‐8 (del(T6‐CUB)) and CUB domains (delCUB) are dispensable under these assay conditions. In addition, mADAMTS13 fragments without the spacer domain (MDT and M) had reduced catalytic efficiencies. Our results hence indicate that similar domains in murine and human ADAMTS13 are required for activity in vitro, supporting the use of mouse models to study ADAMTS13 function in vivo. Interestingly, using intravital microscopy we show that removal of the CUB domains abolishes proteolysis of platelet‐decorated VWF strings in vivo. In addition, whereas MDTCS is fully active in vivo, partial (del(T6‐CUB)) or complete (delCUB) addition of the T2‐8 domains gradually attenuates its activity. Conclusions: Our data demonstrate that the ADAMTS13 CUB and T2‐8 domains influence proteolysis of platelet‐decorated VWF strings in vivo.


Biomaterials | 2011

MRI assessment of blood outgrowth endothelial cell homing using cationic magnetoliposomes.

Stefaan Soenen; Simon F. De Meyer; Tom Dresselaers; Greetje Vande Velde; Inge Pareyn; Kevin Braeckmans; Marcel De Cuyper; Uwe Himmelreich; Karen Vanhoorelbeke

The use of contrast material to stimulate magnetic resonance imaging (MRI) of migrating cells has become an important area of research. In the present study, cationic magnetoliposomes (MLs) were used to magnetically label human blood outgrowth endothelial cells (BOECs) and follow their homing by magnetic resonance imaging (MRI). The biodistribution and functional integration capacity of BOECs, which have shown extensive promise as gene delivery vehicles, have thus far only rarely been investigated. MLs were avidly internalized by BOECs giving clear MRI contrast in phantom studies and the magnetic labeling did not affect cell proliferation, viability, morphology or homeostasis and elicited only minor reactive oxygen species levels. Intravenous injection of labeled BOECs was compared with injection of free MLs and unlabeled BOECs, resulting in homing of BOECs toward the liver and spleen, which was confirmed by histology. The MLs used offer great potential for cellular tracking studies by MRI when low levels of widely distributed cells are present. In particular, the use of these MLs will allow to evaluate the efficacy of new methods to enhance BOEC homing and integration to optimize their use as efficient vehicles for gene therapy.


Journal of Biological Chemistry | 2009

The Novel S527F Mutation in the Integrin β3 Chain Induces a High Affinity αIIbβ3 Receptor by Hindering Adoption of the Bent Conformation

Karen Vanhoorelbeke; Simon F. De Meyer; Inge Pareyn; Chantal Melchior; Sébastien Plançon; Christiane Margue; Olivier Pradier; Pierre Fondu; Nelly Kieffer; Timothy A. Springer; Hans Deckmyn

Three heterozygous mutations were identified in the genes encoding platelet integrin receptor αIIbβ3 in a patient with an ill defined platelet disorder: one in the β3 gene (S527F) and two in the αIIb gene (R512W and L841M). Five stable Chinese hamster ovary cell lines were constructed expressing recombinant αIIbβ3 receptors bearing the individual R512W, L841M, or S527F mutation; both the R512W and L841M mutations; or all three mutations. All receptors were expressed on the cell surface, and mutations R512W and L841M had no effect on integrin function. Interestingly, the β3 S527F mutation produced a constitutively active receptor. Indeed, both fibrinogen and the ligand-mimetic antibody PAC-1 bound to non-activated αIIbβ3 receptors carrying the S527F mutation, indicating that the conformation of this receptor was altered and corresponded to the high affinity ligand binding state. In addition, the conformational change induced by S527F was evident from basal anti-ligand-induced binding site antibody binding to the receptor. A molecular model bearing this mutation was constructed based on the crystal structure of αIIbβ3 and revealed that the S527F mutation, situated in the third integrin epidermal growth factor-like (I-EGF3) domain, hindered the αIIbβ3 receptor from adopting a wild type-like bent conformation. Movement of I-EGF3 into a cleft in the bent conformation may be hampered both by steric hindrance between Phe527 in β3 and the calf-1 domain in αIIb and by decreased flexibility between I-EGF2 and I-EGF3.

Collaboration


Dive into the Inge Pareyn's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Nele Vandeputte

Katholieke Universiteit Leuven

View shared research outputs
Top Co-Authors

Avatar

Simon F. De Meyer

Katholieke Universiteit Leuven

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Aline Vandenbulcke

Katholieke Universiteit Leuven

View shared research outputs
Top Co-Authors

Avatar

Claudia Tersteeg

Katholieke Universiteit Leuven

View shared research outputs
Top Co-Authors

Avatar

Elien Roose

Katholieke Universiteit Leuven

View shared research outputs
Top Co-Authors

Avatar

Hendrik B. Feys

Katholieke Universiteit Leuven

View shared research outputs
Researchain Logo
Decentralizing Knowledge