Thomas Vorup-jensen | Aarhus University (original) (raw)

Papers by Thomas Vorup-jensen

The Journal of biological chemistry, Jan 19, 2007

The interactions between cell surface receptors and sulfated glucosamineglycans serve ubiquitous ... more The interactions between cell surface receptors and sulfated glucosamineglycans serve ubiquitous roles in cell adhesion and receptor signaling. Heparin, a highly sulfated polymer of uronic acids and glucosamine, binds strongly to the integrin receptor alphaXbeta2 (p150,95, CD11c/CD18). Here, we analyze the structural motifs within heparin that constitute high affinity binding sites for the I domain of integrin alphaXbeta2. Heparin oligomers with chain lengths of 10 saccharide residues or higher provide strong inhibition of the binding by the alphaX I domain to the complement fragment iC3b. By contrast, smaller oligomers or the synthetic heparinoid fondaparinux were not able to block the binding. Semipurified heparin oligomers with 12 saccharide residues identified the fully sulfated species as the most potent antagonist of iC3b, with a 1.3 microM affinity for the alphaX I domain. In studies of direct binding by the alphaX I domain to immobilized heparin, we found that the interactio...

Proceedings of the National Academy of Sciences of the United States of America, Jan 18, 2003

The integrin alpha X beta 2 (CD11c/CD18, p150,95) binds ligands through the I domain of the alpha... more The integrin alpha X beta 2 (CD11c/CD18, p150,95) binds ligands through the I domain of the alpha X subunit. Ligands include the complement factor fragment iC3b, a key component in the innate immune defense, which, together with the expression of alpha X beta 2 on dendritic cells and on other leukocytes, suggests a role in the immune response. We now report the structure of the alpha X I domain resolved at 1.65 A by x-ray crystallography. To analyze structural requirements for ligand binding we made a mutation in the alpha X I domain C-terminal helix, which increased the affinity for iC3b approximately 200-fold to 2.4 microM compared with the wild-type domain affinity of approximately 400 microM. Gel permeation chromatography supported a conformational change between the wild-type and mutated domains. Conservation of allosteric regulation in the alpha X I domain points to the functional importance of this phenomenon.

International immunopharmacology, 2001

Mannan-binding lectin (MBL) constitutes an important part of the innate immune defence by effecti... more Mannan-binding lectin (MBL) constitutes an important part of the innate immune defence by effecting the deposition of complement on microbial surfaces. MBL deficiency is among the most common primary immunodeficiencies and is associated with recurrent infections and symptoms of poor immune complex clearance. Plasma-derived MBL has been used in reconstitution therapy but concerns over viral contamination and production capacity point to recombinant MBL (rMBL) as a future source of this protein for clinical use. Natural human MBL is an oligomer of up to 18 identical polypeptide chains. The synthesis of rMBL has been accomplished in several mammalian cell lines, however, the recombinant protein differed structurally from natural MBL. In this, study we compare rMBL produced in myeloma cells, Chinese hamster ovary (CHO) cells, human hepatocytes, and human embryonic kidney (HEK) cells. We report that rMBL structurally and functionally similar to natural MBL can be obtained through synthes...

Exhibit Hall B2-C-D Cytokines, Mediators, Cell-cell Adhesion, Cell Trafficking and Angiogenesis I... more Exhibit Hall B2-C-D Cytokines, Mediators, Cell-cell Adhesion, Cell Trafficking and Angiogenesis I (/apps/MyAnnualMeeting/Session/5339) Poster Background/Purpose:

Journal of Biological Chemistry, 2007

Molecular Therapy, 2001

The human plasma protein mannan-binding lectin (MBL) is an essential part of the innate immune de... more The human plasma protein mannan-binding lectin (MBL) is an essential part of the innate immune defense system. Low levels of MBL are associated with recurrent infections and other clinically significant signs of a compromised immune defense. Previous studies have addressed the possibility of reconstitution therapy by the use of recombinant or plasma-derived protein. Natural MBL is a multimeric protein, which

Multiple sclerosis is a disease of the central nervous system, resulting in the demyelination of ... more Multiple sclerosis is a disease of the central nervous system, resulting in the demyelination of neurons, causing mild to severe symptoms. Several anti-inflammatory treatments now play a significant role in ameliorating the disease. Glatiramer acetate (GA) is a formulation of random polypeptide copolymers for the treatment of relapsing-remitting MS by limiting the frequency of attacks. While evidence suggests the influence of GA on inflammatory responses, the targeted molecular mechanisms remain poorly understood. Here, we review the multiple pharmacological modes-of-actions of glatiramer acetate in treatment of multiple sclerosis. We discuss in particular a newly discovered interaction between the leukocyte-expressed integrin α M β 2 (also called Mac-1, complement receptor 3, or CD11b/CD18) and perspectives on the GA co-polymers as an influence on the function of the innate immune system.

Aging of the human body affects the immune system by a decline in the ability to raise a response... more Aging of the human body affects the immune system by a decline in the ability to raise a response to challenges such as microbial infections or vaccinations. In the very elderly, the decline in such functions appears to relate to a reduced expression of certain co-stimulatory molecules expressed by T lymphocytes. More recently, attention has been drawn to the adhesion molecule CD62L, where differences in expression and function of this molecule between younger and older individuals are suspected to be a part of immunosenescence in the elderly.

Molecular and Cellular Therapies, 2013

Influenza is a major challenge to healthcare systems world-wide. While prophylactic vaccination i... more Influenza is a major challenge to healthcare systems world-wide. While prophylactic vaccination is largely efficient, long-lasting immunity has not been achieved in immunized populations, at least in part due to the challenges arising from the antigen variation between strains of influenza A virus as a consequence of genetic drift and shift. From progress in our understanding of the immune system, the mode-of-action of vaccines can be divided into the stimulation of the adaptive system through inclusion of appropriate vaccine antigens and of the innate immune system by the addition of adjuvant to the vaccine formulation. A shared property of many vaccine adjuvants is found in their nature of water-insoluble precipitates, for instance the particulate material made from aluminum salts. Previously, it was thought that embedding of vaccine antigens in these materials provided a "depot" of antigens enabling a long exposure of the immune system to the antigen. However, more recent work points to a role of particulate adjuvants in stimulating cellular parts of the innate immune system. Here, we briefly outline the infectious medicine and immune biology of influenza virus infection and procedures to provide sufficient and stably available amounts of vaccine antigen. This is followed by presentation of the many roles of adjuvants, which involve humoral factors of innate immunity, notably complement. In a perspective of the ultrastructural properties of these humoral factors, it becomes possible to rationalize why these insoluble precipitates or emulsions are such a provocation of the immune system. We propose that the biophysics of particulate material may hold opportunities that could aid the development of more efficient influenza vaccines.

Mannan-binding lectin (MBL) plays a pivotal role in innate immunity by activating complement afte... more Mannan-binding lectin (MBL) plays a pivotal role in innate immunity by activating complement after binding carbohydrate moieties on pathogenic bacteria and viruses. Structural similarities shared by MBL and C1 complexes and by the MBL- and C1q-associated serine proteases, MBL-associated serine protease (MASP)-1 and MASP-2, and C1r and C1s, respectively, have led to the expectation that the pathways of complement activation

Bone, 2014

Osteopontin (OPN) is an acidic, intrinsically disordered extracellular matrix protein with a capa... more Osteopontin (OPN) is an acidic, intrinsically disordered extracellular matrix protein with a capacity to modulate biomineralization in vitro and in vivo. The role of posttranslational modification of osteopontin has been intensively studied. Phosphorylation of OPN has been demonstrated to play a role in inhibition of biomineral formation and growth in vitro. Here, we used isothermal titration calorimetry (ITC) to investigate the ability of OPN to bind the divalent cations Ca(2+) and Mg(2+), both essential components of inorganic minerals in vivo. We found, that bovine OPN binds ~10 Ca(2+) ions with an apparent affinity ~50-fold tighter than Mg(2+), both regardless of OPN phosphorylation, and with affinities significantly stronger than previously reported. These results were confirmed using human derived OPN. This implies that a majority of the acidic residues within OPN must be engaged in calcium interaction under physiological conditions.

Proceedings of the National Academy of Sciences, 2003

The integrin ␣X␤2 (CD11c͞CD18, p150,95) binds ligands through the I domain of the ␣X subunit. Lig... more The integrin ␣X␤2 (CD11c͞CD18, p150,95) binds ligands through the I domain of the ␣X subunit. Ligands include the complement factor fragment iC3b, a key component in the innate immune defense, which, together with the expression of ␣X␤2 on dendritic cells and on other leukocytes, suggests a role in the immune response. We now report the structure of the ␣X I domain resolved at 1.65 Å by x-ray crystallography. To analyze structural requirements for ligand binding we made a mutation in the ␣X I domain C-terminal helix, which increased the affinity for iC3b Ϸ200-fold to 2.4 M compared with the wild-type domain affinity of Ϸ400 M.

Proceedings of the National Academy of Sciences, 2005

The structural integrity of tissue proteins is damaged in processes ranging from remodeling of th... more The structural integrity of tissue proteins is damaged in processes ranging from remodeling of the extracellular matrix to destruction by microbial pathogens. Leukocytes play a prominent role in tissue surveillance and repair. However, it remains enigmatic what features of structurally decayed proteins prompt recognition by leukocyte cell-surface receptors. Here, we report that adhesion of human neutrophil granulocytes to fibrinogen is greatly increased by plasmin digestion in a mode where ␣X␤2 dominates the integrindependent binding. The bacterial protease subtilisin also enhances binding by ␣X␤2. The ␣X ligand binding domain has an unusually high affinity for carboxyl groups, with KD at Ϸ100 M. Our findings implicate enhanced accessibility of negatively charged residues in structurally decayed proteins as a pattern recognition motif for ␣ X ␤ 2 integrin. Comparisons among integrins show relevance of these findings to the large number of ligands recognized by ␣M␤2 and ␣X␤2 but not ␣L␤2. The observations suggest that the pericellular proteolysis at the leading edge of neutrophils not only facilitates passage through the extracellular matrix but also manufactures binding sites for ␣X␤2.

Molecular Immunology, 2010

to play a crucial role in exposing its thioester bond to nucleophilic attack at a broad conformat... more to play a crucial role in exposing its thioester bond to nucleophilic attack at a broad conformational range of antigenic surfaces.

Molecular Immunology, 1998

Molecular Immunology, 2011

Heteroclitic monoclonal antibodies are characterized by the ability to bind multiple epitopes wit... more Heteroclitic monoclonal antibodies are characterized by the ability to bind multiple epitopes with little or no similarity. Such antibodies have been reported earlier, but insight into to the molecular basis of this propensity is limited. Here we report that the KIM185 antibody to human CD18 reacts with the plasma protein C4b-binding protein (C4BP). This was revealed during affinity purification procedures where human serum was incubated with surfaces coated with monoclonal antibodies to CD18. Other monoclonal antibodies to CD18 (KIM127 and TS1/18) showed no such interaction with C4BP. We constructed a sandwich-type time-resolved immunofluorometric assay using KIM185 both as capture and developing antibody. By use of proteolytic fragments of KIM185 and recombinant deletion mutants of C4BP the interaction sites were mapped to the variable region of KIM185 and the oligomerization domain of C4BP, respectively. C4BP is a large oligomeric plasma protein that binds activated complement factor C4b and other endogenous ligands as well as microorganisms. By use of the recent crystallographic data on the structure of CD11c/CD18 and prediction of the secondary structure of the C4BP oligomerization domain, we show that epitopes bound by KIM185 in these proteins are unlikely to share any major structural similarity. However, both antigens may form oligomers that would enable avid binding by the antibody. Our report points to the astonishing ability of heteroclitic antibodies to accommodate the binding of multiple proteins with no or little structural similarity within the confined space of the variable regions.