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Biomedical subjects

G Opdenakker

Publications and source records attributed to G Opdenakker.

At least 55 records · Page 3Linked to original sources
PubMed1999

Prevention of interleukin-8-induced mobilization of hematopoietic progenitor cells in rhesus monkeys by inhibitory antibodies against the metalloproteinase gelatinase B (MMP-9).

Previously, we demonstrated that IL-8 induces rapid mobilization of hematopoietic progenitor cells (HPC) from the bone marrow of rhesus monkeys. Because activation of neutrophils by IL-8 induces the release of gelatinase B (MMP-9), which is involved in the degradation of extracellular matrix molecules, we hypothesized that MMP-9 release might induce stem cell mobilization by cleaving matrix molecules to which stem cells are attached. Rhesus monkeys were treated with a single i.v. injection of 0.1 mg/kg human IL-8, which resulted in a 10- to 100-fold increase in HPC within 30 min after injection. Zymographic analysis revealed a dramatic instantaneous increase in the plasma levels of MMP-9, followed by the increase in circulating HPC. Enzyme levels decreased at 2 h after injection of IL-8, simultaneously with the decrease in the numbers of circulating HPC. To test the hypothesis that MMP-9 induction was involved in HPC mobilization, rhesus monkeys were treated with a highly specific inhibitory monoclonal anti-gelatinase B antibody. Anti-gelatinase B at a dose of 1-2 mg/kg completely prevented the IL-8-induced mobilization of HPC, whereas a dose of 0.1 mg/kg had only a limited effect. Preinjection of inhibitory antibodies did not preclude the IL-8-induced production and secretion of MMP-9. Pretreatment with an irrelevant control antibody did not affect IL-8-induced mobilization, showing that the inhibition by the anti-gelatinase B antibody was specific. In summary, IL-8 induces the rapid systemic release of MMP-9 with concurrent mobilization of HPC that is prevented by pretreatment with an inhibitory anti-gelatinase B antibody, indicating that MMP-9 is involved as a mediator of the IL-8-induced mobilization of HPC.

Animals↗
PubMed1999

Gelatinase B (MMP-9), but not its inhibitor (TIMP-1), dictates the growth rate of experimental thymic lymphoma.

Dysregulation of metalloproteinase production at tumor sites contributes to the modification of local stromal tissue necessary for tumor development. Gelatinase B (matrix metalloproteinase-9, MMP-9) is one of the key enzymes that have been associated with the progression of several tumors. Paradoxically, MMP-9 expression by tumor cells, most notably by lymphoma cells, is concomitant with the expression of its physiological inhibitor, TIMP-1. Not only are both genes often co-expressed in the most aggressive forms of lymphomas but also both are up-regulated upon contact with stromal cells. Since TIMP-1 is known to regulate growth in several cell types and some aggressive lymphoma cells express TIMP-1 constitutively without MMP-9, it is unclear whether the over-expression of MMP-9 is counterbalanced by TIMP-1 and whether TIMP-1 expression alone could favor the development of lymphoma. To gain further insight into the respective roles of MMP-9 and TIMP-1 in lymphoma, we generated lymphoma cell lines expressing constitutively high levels of MMP-9 or TIMP-1 and compared these cells for the ability to form thymic lymphoma in vivo. Moreover, we generated lymphoma cell lines expressing constitutively high levels of both MMP-9 and TIMP-1 to reproduce the net physiological balance resulting from the expression of both genes simultaneously and to determine which gene overrides the other. Our results show that mice injected with lymphoma cells expressing MMP-9 constitutively developed thymic lymphoma more rapidly than those injected with control lymphoma cells. Over-expression of TIMP-1 alone did not significantly influence tumor progression of lymphoma nor did it delay the capacity of MMP-9 to accelerate the development of thymic lymphoma.

Animals↗
PubMed1999

Biology of IL-8-induced stem cell mobilization.

The CXC chemokine interleukin-8 (IL-8) has profound hematopoietic activities following systemic administration. It induces the rapid mobilization of cells with lymphomyeloid repopulating ability in mice and of hematopoietic progenitor cells in monkeys. In this paper, evidence is presented that stem cell mobilization in mice requires the functional expression on the beta 2-integrin leukocyte function-associated antigen-1 (LFA-1). In monkeys, systemic injection of IL-8 is followed by a significant increase in the circulating levels of the matrix metallo proteinase gelatinase-B (MMP-9). Based on these findings, the hypothesis is discussed that mature neutrophils serve as intermediate cells in IL-8-induced stem cell mobilization by the release of proteinases.

Animals↗
PubMed1999

CD26/dipeptidyl-peptidase IV down-regulates the eosinophil chemotactic potency, but not the anti-HIV activity of human eotaxin by affecting its interaction with CC chemokine receptor 3.

Chemokines attract and activate distinct sets of leukocytes. The CC chemokine eotaxin has been characterized as an important mediator in allergic reactions because it selectively attracts eosinophils, Th2 lymphocytes, and basophils. Human eotaxin has a penultimate proline, indicating that it might be a substrate for dipeptidyl-peptidase IV (CD26/DPP IV). In this study we demonstrate that eotaxin is efficiently cleaved by CD26/DPP IV and that the NH2-terminal truncation affects its biological activity. CD26/DPP IV-truncated eotaxin(3-74) showed reduced chemotactic activity for eosinophils and impaired binding and signaling properties through the CC chemokine receptor 3. Moreover, eotaxin(3-74) desensitized calcium signaling and inhibited chemotaxis toward intact eotaxin. In addition, HIV-2 infection of CC chemokine receptor 3-transfected cells was inhibited to a similar extent by eotaxin and eotaxin(3-74). Thus, CD26/DPP IV differently regulates the chemotactic and antiviral potencies of eotaxin by the removal of two NH2-terminal residues. This physiological processing may be an important down-regulatory mechanism, limiting eotaxin-mediated inflammatory responses.

Anti-HIV Agents↗
PubMed1999

Microsatellite polymorphisms in the gene promoter of monocyte chemotactic protein-3 and analysis of the association between monocyte chemotactic protein-3 alleles and multiple sclerosis development.

Monocyte chemotactic protein 3 (MCP-3) is a chemokine that attracts mononuclear cells, including monocytes and lymphocytes, the inflammatory cell types that predominate in multiple sclerosis lesions. We studied the possible association between the presence of a CA/GA microsatellite repeat polymorphism in the promoter/enhancer region of the MCP-3 gene and the occurrence of multiple sclerosis. DNA samples from 192 Swedish multiple sclerosis (MS) patients and 129 healthy controls were analysed by an automated fluorescent technique. In the whole sample population, five MCP-3 allele variants (MCP-3*A1 to MCP-3*A5) were detected with an allele frequency ranging between 0.3% and 46%. The individual MCP-3 allele frequencies did not differ significantly between MS patients and control individuals. The relative MS risk, attributable to HLA-DRB1*15 was 3.05 (chi2 = 22.25, p < 0.0001). The phenotype frequency (PF) of none of the MCP-3 alleles was significantly altered in the population of controls versus unselected MS patients. When MS patients and control subjects were stratified according to positivity for HLA-DRB1*15, the MCP-3*A4-associated risk for developing MS decreased to 0.36 (p = 0.011). In the stratified groups of patients who were negative for both HLA-DRB1*15 and HLA-DRB1*03, and hence possessed a lower risk to develop MS, the MCP-3*A2-associated risk for MS development decreased significantly (p = 0.018). We conclude that the MCP-3*A4 allele might protect against MS development on the background of the increased risk in HLA-DRB1*15+ individuals and the MCP-3*A2 allele seems protective in low-risk individuals, who are both negative for DRB1*03 and DRB1*15.

Alleles↗
PubMed1999

Truncation of macrophage-derived chemokine by CD26/ dipeptidyl-peptidase IV beyond its predicted cleavage site affects chemotactic activity and CC chemokine receptor 4 interaction.

The serine protease CD26/dipeptidyl-peptidase IV (CD26/DPP IV) and chemokines are known key players in immunological processes. Surprisingly, CD26/DPP IV not only removed the expected Gly1-Pro2 dipeptide from the NH2 terminus of macrophage-derived chemokine (MDC) but subsequently also the Tyr3-Gly4 dipeptide, generating MDC(5-69). This second cleavage after a Gly residue demonstrated that the substrate specificity of this protease is less restricted than anticipated. The unusual processing of MDC by CD26/DPP IV was confirmed on the synthetic peptides GPYGANMED (MDC(1-9)) and YGANMED (MDC(3-9)). Compared with intact MDC(1-69), CD26/DPP IV-processed MDC(5-69) had reduced chemotactic activity on lymphocytes and monocyte-derived dendritic cells, showed impaired mobilization of intracellular Ca2+ through CC chemokine receptor 4 (CCR4), and was unable to desensitize for MDC-induced Ca2+-responses in CCR4 transfectants. However, MDC(5-69) remained equally chemotactic as intact MDC(1-69) on monocytes. In contrast to the reduced binding to lymphocytes and CCR4 transfectants, MDC(5-69) retained its binding properties to monocytes and its anti-HIV-1 activity. Thus, NH2-terminal truncation of MDC by CD26/DPP IV has profound biological consequences and may be an important regulatory mechanism during the migration of Th2 lymphocytes and dendritic cells to germinal centers and to sites of inflammation.

Binding, Competitive↗
PubMed1999

Plasminogen activators and matrix metalloproteases, mediators of extracellular proteolysis in inflammatory demyelination of the central nervous system.

The role of extracellular proteolysis in inflammatory demyelination, originally hypothesized as a mechanism for myelin degradation, is increasingly recognized as a pathogenetic step and as a target for therapy in human demyelinating disease. The activation of ubiquitous plasminogen by urokinase (u-PA) and tissue-type plasminogen activator (t-PA), which is associated with various neuropathologies, including multiple sclerosis (MS), is the key initiator of the activation cascade of the four classes of matrix metalloproteinases (MMPs): collagenases, stromelysins, membrane-type metalloproteinases and gelatinases. Spatiotemporal protein and mRNA expression of gelatinase B (MMP-9) and matrilysin (MMP-7) have been documented respectively in MS lesions and in the central nervous system (CNS) of animals developing experimental autoimmune encephalomyelitis (EAE). A close interaction between disease-promoting cytokines and extracellularly acting proteases is deduced from in vitro experiments. Cytokines regulate the balance between the proteases and their respective specific inhibitors at the transcriptional level, while proteolysis is a reciprocal mechanism to enhance (by activation) or downmodulate (by degradation) the specific activities of cytokines. In acute inflammation the contribution of chemokines is hierarchically organised, interleukin-8 (IL-8) and related CXC-chemokines inducing a rapid influx of neutrophils in the acute lesions and an instantaneous exocytosis of gelatinase B granules. This results in sudden and extensive damage to the CNS. In chronic disease involving autoimmune processes CC-chemokines that act mainly on mononuclear cell types appear to be more strictly regulated. As MMPs modify matrix components, promoting extravasation of lymphocytes and monocytes/macrophages and have the potential to generate encephalitogenic peptides from myelin basic protein, novel treatments for demyelinating diseases may be predicted by specific inhibition of these enzymes. Here we review plasminogen activators and the MMP family, in the context of their role in CNS inflammation and demyelination and highlight studies in which intervention in these protease cascades are and may be used to treat demyelinating diseases.

Animals↗
PubMed1999

Regulation of gelatinases in microglia and astrocyte cell cultures by plant lectins.

The effects of 25 recently discovered plant lectins on cell proliferation and enzyme release were compared to those of previously known lectins on rat microglia and astrocyte cell cultures. A dose-dependent proliferation of microglial cells, but not of astrocytes, was induced by seven lectins, whereas five lectins showed dose-dependent cytotoxicity on both microglia and astrocyte cell cultures. The activity of gelatinase B (MMP-9) was strongly increased in microglial cells by the aforementioned seven lectins, by concanavalin A, and by phytohemagglutinin (PHA-E4), whereas gelatinase A (MMP-2) remained at constitutive levels. The five cytotoxic lectins decreased the activity of gelatinase B in microglia and of gelatinase A in astrocytes, in a dose-dependent manner. The lectin wheat germ agglutinin induced a decrease in gelatinase B activity in microglia, but stimulated gelatinase A and B activity in astrocytes. These results indicate that lectins possess neuromodulatory effects that may motivate the study of their effects on central nervous system (CNS) function in vivo. This, in turn, may lead to better insight into whether lectin or lectin-like molecules can interact with glial cells, and whether they have a role in acute toxicity and in multifactorial diseases in which environmental factors may play a role.

Animals↗
PubMed1999

Differential induction of monocyte chemotactic protein-3 in mononuclear leukocytes and fibroblasts by interferon-alpha/beta and interferon-gamma reveals MCP-3 heterogeneity.

Monocyte chemotactic protein-3 (MCP-3) is a pluripotent CC chemokine, attracting most leukocytic cell types. With the use of a sensitive and specific ELISA, MCP-3 was found to be inducible in fibroblasts and peripheral blood mononuclear cells (PBMC) by cytokines and cytokine inducers. MCP-3 production levels (1-10 ng/ml) were tenfold lower compared to those of MCP-1. In diploid fibroblasts, synergistic induction of MCP-3, but not of MCP-1, mRNA and protein was observed by combined treatment with IL-1beta and IFN-gamma. In PBMC, IFN-alpha and IFN-beta (but not IFN-gamma), as well as measles virus and double-stranded RNA, were potent inducers of MCP-3, which suggests a role for this chemokine in an early stage of viral infections. In contrast, endotoxin failed to induce MCP-3 production in fibroblasts and PBMC. Purification of MCP-3 from PBMC revealed biochemical heterogeneity. In monocyte chemotaxis and calcium mobilization assays, pure 11-kDa MCP-3 from PBMC showed similar potencies as MCP-3 from tumor cells. It was concluded that the induction of MCP-3 by IFN is regulated differently in fibroblasts and PBMC. In view of the multiple target cells for MCP-3, local and strictly regulated chemokine production might be important to conduct selectively the immune response in infection or inflammation.

Cells, Cultured↗
PubMed1999

Transcriptional control of the human MCP-2 gene promoter by IFN-gamma and IL-1beta in connective tissue cells.

Human monocyte chemotactic protein-2 (MCP-2) is a member of the CC chemokine family. It is produced by mononuclear leukocytes, diploid fibroblasts, and tumor cells after induction with IL-1beta or IFN-gamma. To understand the transcriptional regulation of the gene, we have analyzed the structure and function of the promoter region. The sequence of the 5'-flanking region was determined and the transcription start site was found to be located at 68 nucleotides upstream of the ATG translation start codon. 5'-Deletion mutants were generated and transfected into E6SM diploid fibroblasts and MG-63 osteosarcoma cells. Expression was measured by luciferase assay in transfected unstimulated cells and after stimulation with IL-1beta, IFN-gamma, or a combination. The region between nucleotides -143 and -73 (relative to the transcription initiation site), containing putative cis-elements for GATA-1, H-APF1, AP-1, and GAS, is important for basal transcription levels in both cell lines. Stimulation for 18 h with IL-1beta alone failed to affect expression of any of the constructs both in diploid fibroblasts and in osteosarcoma cells. In both cell lines IFN-gamma increased the activity of all mutants that possessed the region between -340 and -301. In MG-63 cells, stimulation with the combination of IL-1beta and IFN-gamma caused an additional increase in expression of the constructs from -340 onward. Finally, the presence of transcription factors in nuclear extracts of MG-63 cells and their specificity to bind to various oligonucleotide probes in this [-340; -301] region were evidenced by electromobility shift assays. These results show that IFN-gamma, produced by lymphocytes and NK cells, induces the transcription of the MCP-2 gene in fibroblasts and thereby can indirectly contribute to recruitment of various leukocyte cell types to inflammatory sites.

Base Sequence↗
PubMed1999

Wernicke encephalopathy: MR findings in two patients.

Wernicke encephalopathy is a serious neurologic disorder caused by vitamin-B1 or thiamine deficiency. In the literature the characteristic symmetric paraventricular lesions of Wernicke encephalopathy are hyperintense on T2-weighted sequences spin-echo (SE) and enhance on T1-weighted SE sequences after intravenous gadolinium administration in the acute phase. We present two patients in the acute phase of Wernicke encephalopathy with special reference to the MR imaging. One of our reported cases is special because of the MR demonstration of a hemorrhagic focus in the caput of the right nucleus caudatus. The other case demonstrates no enhancement on SE T1-weighted sequences after intravenous gadolinium administration.

Aged↗
PubMed1999

The MCP/eotaxin subfamily of CC chemokines.

Migration of leukocytes from the bone marrow to the circulation, the primary lymphoid organs and inflammatory sites is directed by chemokines and specific receptor interactions. Besides the role of this group of low molecular weight cytokines in leukocyte attraction and activation, anti-HIV and hematopoietic activities were also attributed to chemokines. On the basis of the number and arrangement of the conserved cysteines, chemokines are subdivided in two multi-member families, namely the CXC and CC chemokines, whereas fractalkine (CX3C) and lymphotactin (C) are unique relatives. The CC chemokines possess four cysteines of which the first two are adjacent. Functionally, they form a rather heterogeneous family. Here, the focus is on the monocyte chemotactic proteins and eotaxin which, on a structural basis, can be considered as a CC chemokine subfamily. Not only the protein sequences, but also the gene structures, chromosomal location, biological activities and receptor usage exhibit considerable similarities. The review is complemented with a comparison of the biological functions of the MCP/eotaxin-subfamily in physiology and pathology.

Amino Acid Sequence↗
PubMed1999

Analysis of an IFN-gamma gene (IFNG) polymorphism in multiple sclerosis in Europe: effect of population structure on association with disease.

An intronic dinucleotide polymorphism in the IFN-gamma gene (IFNG) was used as a marker for testing association with multiple sclerosis (MS). Disease association was analyzed in case-control sets sampled from four geographically separate European populations (Germany, Northern Italy, Sardinia, and Sweden). Only in the Swedish was a weak disease association of the IFNG allele pattern found, mainly due to a higher frequency of IFNG allele I1 in MS patients. No evidence for association was found in the German or Northern Italian populations. These results contrast with the situation in Sardinia. We have recently reported transmission disequilibrium of IFNG allele I2 in Sardinian MS siblings not carrying the predisposing DRB1 *03 or *04 alleles (Ann. Neurol. 44, 841-842, 1998). Further analysis now shows that I2 is significantly more often transmitted to DRB1 *03-/*04- males, than to DRB1 *03-/*04- females. The odds ratio (OR) for IFNG-associated susceptibility to MS in the total Sardinian DRB1*03-/*04- group was 1.88 for I2 heterozygotes but amounted to 8.235 for I2 homozygotes, suggestive of a recessive mode of inheritance. Score test-based statistics pointed to an I2 allele dosage effect acting in susceptibility. Comparison of the IFNG allele frequencies in seven European populations (Northern Finnish, Southern Finnish, Swedish, Danish, German, Italian, and Sardinian) revealed a highly different distribution pattern. We introduced latitude as a score variable in order to test for trend in binomial proportions. This test statistic showed that for both most common alleles, I1 and I2 (compiled allele frequency about 85%), a significant opposite north-to-south trend is seen throughout Europe. This effect is primarily due to the extreme values found in the outlier populations of Finland and Sardinia. Our findings are discussed with respect to recent literature pertinent to the role of the IFNG chromosome region in autoimmune diseases.

Alleles↗
PubMed1999

Expression of monocyte chemotactic protein (MCP)-1, MCP-2, and MCP-3 by human airway smooth-muscle cells. Modulation by corticosteroids and T-helper 2 cytokines.

We have demonstrated that, in addition to their contractile function, human airway smooth-muscle cells (HASMC) are able to express and to secrete chemokines of the monocyte chemotactic protein (MCP)/ eotaxin subfamily. This group of chemokines is believed to play a fundamental role in the development of allergic airway diseases such as asthma. The expression levels of MCP (MCP-1, -2, and -3) messenger RNA (mRNA) were compared with those of regulated on activation, normal T cells expressed and secreted (RANTES) mRNA in HASMC in culture. HASMC express MCP and RANTES mRNA after stimulation with interleukin (IL)-1beta, tumor necrosis factor-alpha, and interferon-gamma. MCP mRNA was maximal at 8 h, whereas RANTES mRNA expression was delayed to 24 h after stimulation. Further, significant differences were observed in the induction patterns of MCP and RANTES mRNA expression after stimulation with the individual cytokines. Dexamethasone (DEX) significantly inhibited cytokine-induced accumulation of MCP and RANTES mRNA, in contrast to IL-4, IL-10, and IL-13, which had no inhibitory effect on cytokine-induced chemokine expression. The cytokine-induced MCP mRNA expression in HASMC was associated with MCP release, which was inhibited by DEX and post-translationally by IL-4. HASMC can actively participate in the pathogenesis of asthma by the expression and release of chemokines, which are likely to play a critical role in the generation and regulation of the inflammatory response characteristic of allergic airway diseases.

Bronchi↗
PubMed1999

Resistance of young gelatinase B-deficient mice to experimental autoimmune encephalomyelitis and necrotizing tail lesions.

Regulated expression of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) plays a role in various physiological processes. To determine in vivo how unbalanced expression of these factors can promote or affect the course of pathologies, we knocked out the mouse gelatinase B gene by replacing the catalytic and zinc-binding domains with an antisense-oriented neomycin resistance gene. Adult gelatinase B-deficient mice and wild-type controls could be induced to develop experimental autoimmune encephalomyelitis (EAE) with similar scores for neurologic disease, blood-brain barrier permeability, and central nervous system histopathology. However, whereas diseased control animals showed necrotizing tail lesions with hyperplasia of osteocartilaginous tissue, adult gelatinase B-deficient mice were resistant to this tail pathology. Gelatinase B-deficient mice younger than 4 weeks of age were significantly less susceptible to the development of EAE than were age matched controls and, even as they aged, they remained resistant to tail lesions. These data illustrate that gelatinase B expression plays a role in the development of the immune system and that, in ontogenesis, the propensity to develop autoimmunity is altered by the absence of this MMP.

Age Factors↗