Search PubMed⌕ Search

Biomedical subjects

D Elewaut

Publications and source records attributed to D Elewaut.

At least 37 records · Page 2Linked to original sources
PubMed2000

Influence of aging on the synthesis and morphology of the aggrecans synthesized by differentiated human articular chondrocytes.

OBJECTIVE: Synthesis rates of aggrecans by phenotypically stable human articular chondrocytes and the immobilization of these aggrecans in large aggregates were used as variables reflecting the capability of these cells of restoring the extracellular matrix of articular cartilage in vivo in an aging population. DESIGN: Human articular chondrocytes were isolated from articular cartilage obtained from 33 different donors at autopsy. The chondrocytes were cultured in gelled agarose. Synthesis of aggrecans was investigated using Na(2)(35)SO(4)as a radioactive precursor after a 2-week culture period. Electron microscopic study of aggrecan aggregates was done on the macromolecules accumulated over 3 weeks in culture by the chondrocytes obtained from eight other donors with increasing ages. RESULTS: Sulfate incorporation rates into aggrecans correlated inversely with the age of the donor. The value of sulfate incorporation in aggrecans for chondrocytes obtained from mature cartilage of a 20-year-old individual in this system drops to 50% and 25% for chondrocytes obtained from 45- and 69-year-old individuals respectively. Electron microscopic study of aggrecan aggregates showed that the 'de novo' synthesized hyaluronan molecules were fully loaded with aggrecans. Mature human articular cartilage cells were found to synthesize an aggrecan aggregate which carried an average number of 11.7 to 13.1 aggrecans. Cells obtained from immature donors synthesized aggrecan aggregates of which the hyaluronan chain carried twice the amount of aggrecans. These immature human articular cartilage cells were also found to synthesize significant proportions of large aggrecan aggregates with 20 to over 100 aggrecans immobilized on a single hyaluronan chain. The proportions of these large aggrecan aggregates decreased with increasing age of the donors of the chondrocytes. CONCLUSION: The declining aggrecan synthesis rates and the decreased capability of assembling large molecular size aggregates with increasing age in humans illustrates a progressive failure of the repair function of articular cartilage cells in humans.

Adolescent↗
PubMed2000

Focal up-regulation of E-cadherin-catenin complex in inflamed bowel mucosa but reduced expression in ulcer-associated cell lineage.

The E-cadherin-catenin complex is important for the maintenance of epithelial architecture. We studied its expression in Crohn disease, ulcerative colitis, acute ileitis, and controls. Immunohistochemical stainings for E-cadherin, alpha-catenin, beta-catenin and gamma-catenin were performed. E-cadherin messenger RNA (mRNA) was detected using riboprobes. In active inflammation, there was up-regulation of the complex. In particular, epithelium adjacent to ulcers showed increased expression of protein and mRNA, but in ulcer-associated cell lineage, the intensity of staining was weak to negative. In focal inflammation, up-regulation was found in affected areas. Reparative epithelium growing over denuded areas showed weaker expression. Since structural or functional perturbation in any of the molecules of the E-cadherin-catenin complex results in loss of intercellular adhesion, the preexistent epithelium may benefit from up-regulation to try to maintain its normal architecture under inflammatory conditions. Reduced expression in reparative epithelium and ulcer-associated cell lineage could facilitate the motility of these cells.

Cadherins↗
PubMed2000

Subclinical gut inflammation in spondyloarthropathy patients is associated with upregulation of the E-cadherin/catenin complex.

OBJECTIVE: Previously an upregulation of E-cadherin and its associated molecules alpha-catenin, beta-catenin and plakoglobin has been demonstrated in clinically overt inflammatory bowel disease (IBD). The aim of this study was to investigate the expression of the E-cadherin/catenin complex in subclinically inflamed bowel mucosa from spondyloarthropathy (SpA) patients. METHODS: Ileal and colonic biopsy specimens from 19 SpA patients with subclinical inflammatory gut lesions and from seven controls were stained with monoclonal antibodies against E-cadherin, beta-catenin and plakoglobin and a polyclonal antibody against alpha-catenin. E-cadherin mRNA was detected using a riboprobe. Inflammation was histologically classified into acute, chronic active and chronic quiescent forms. RESULTS: In acute and chronic active bowel inflammation of SpA patients, upregulation of the E-cadherin/catenin glycoprotein complex could be observed. Chronic lesions in a quiescent state did not show such an upregulation. Furthermore, chronic inflammation was associated with an increase in E-cadherin mRNA. CONCLUSIONS: As some of the SpA patients with subclinical gut inflammation develop IBD, upregulation of the E-cadherin/catenin complex in inflamed bowel mucosa from SpA patients may point to early cellular changes in the development of IBD. However, at present it cannot be excluded that increased E-cadherin/catenin complex expression is a bystander phenomenon of active inflammation.

Acute Disease↗
PubMed1999

Expression and regulation of the human beta-defensins hBD-1 and hBD-2 in intestinal epithelium.

The intestinal epithelium forms a physical barrier to limit access of enteric microbes to the host and contributes to innate host defense by producing effector molecules against luminal microbes. To further define the role of the intestinal epithelium in antimicrobial host defense, we analyzed the expression, regulation, and production of two antimicrobial peptides, human defensins hBD-1 and hBD-2, by human intestinal epithelial cells in vitro and in vivo. The human colon epithelial cell lines HT-29 and Caco-2 constitutively express hBD-1 mRNA and protein but not hBD-2. However, hBD-2 expression is rapidly induced by IL-1alpha stimulation or infection of those cells with enteroinvasive bacteria. Moreover, hBD-2 functions as a NF-kappaB target gene in the intestinal epithelium as blocking NF-kappaB activation inhibits the up-regulated expression of hBD-2 in response to IL-1alpha stimulation or bacterial infection. Caco-2 cells produce two hBD-1 isoforms and a hBD-2 peptide larger in size than previously described hBD-2 isoforms. Paralleling the in vitro findings, human fetal intestinal xenografts constitutively express hBD-1, but not hBD-2, and hBD-2 expression, but not hBD-1, is up-regulated in xenografts infected intraluminally with Salmonella. hBD-1 is expressed by the epithelium of normal human colon and small intestine, with a similar pattern of expression in inflamed colon. In contrast, there is little hBD-2 expression by the epithelium of normal colon, but abundant hBD-2 expression by the epithelium of inflamed colon. hBD-1 and hBD-2 may be integral components of epithelial innate immunity in the intestine, with each occupying a distinct functional niche in intestinal mucosal defense.

Anti-Bacterial Agents↗
PubMed1999

NF-kappa B is a central regulator of the intestinal epithelial cell innate immune response induced by infection with enteroinvasive bacteria.

Human intestinal epithelial cells up-regulate the expression of an inflammatory gene program in response to infection with a spectrum of different strains of enteroinvasive bacteria. The conserved nature of this program suggested that diverse signals, which are activated by enteroinvasive bacteria, can be integrated into a common signaling pathway that activates a set of proinflammatory genes in infected host cells. Human intestinal epithelial cell lines, HT-29, Caco-2, and T84, were infected with invasive bacteria that use different strategies to induce their uptake and have different intracellular localizations (i.e., Salmonella dublin, enteroinvasive Escherichia coli, or Yersinia enterocolitica). Infection with each of these bacteria resulted in the activation of TNF receptor associated factors, two recently described serine kinases, I kappa B kinase (IKK) alpha and IKK beta, and increased NF-kappa B DNA binding activity. This was paralleled by partial degradation of I kappa B alpha and I kappa B epsilon in bacteria-infected Caco-2 cells. Mutant proteins that act as superrepressors of IKK beta and I kappa B alpha inhibited the up-regulated transcription and expression of downstream targets genes of NF-kappa B that are key components of the epithelial inflammatory gene program (i.e., IL-8, growth-related oncogene-alpha, monocyte chemoattractant protein-1, TNF-alpha, cyclooxygenase-2, nitric oxide synthase-2, ICAM-1) activated by those enteroinvasive bacteria. These studies position NF-kappa B as a central regulator of the epithelial cell innate immune response to infection with enteroinvasive bacteria.

Caco-2 Cells↗
PubMed1999

Polyarteritis nodosa mimicking polymyalgia rheumatica.

We report a case of polyarteritis nodosa with a clinical presentation mimicking polymyalgia rheumatica, as well as pathological findings of non-giant-cell arteritis on temporal artery biopsy with symptoms of jaw claudication. Although certain clinical syndromes have been attributed to specific types of systemic vasculitis, considerable overlap occurs. Obtaining tissue biopsy in cases of vasculitis is mandatory for diagnosis and classification.

Aged↗
PubMed1999

Needle arthroscopy of the knee with synovial biopsy sampling: technical experience in 150 patients.

Needle arthroscopy is an office-based technique allowing direct visualisation of the knee cavity and selective sampling of the synovial membrane. We performed needle arthroscopy in 150 patients with synovitis of the knee (1) to evaluate the diagnostic potential in early arthritis, (2) to perform therapeutic lavage in persistent inflammatory synovitis and (3) to assess the balance between technical feasibility, safety and patient comfort on the one hand, and the relevance of the obtained macro- and microscopic information for diagnosis and research purposes on the other. After disinfection of the leg and local anaesthesia of the skin and joint, a 1.8-2.7 mm needle arthroscope was introduced into the knee. Synovial fluid was aspirated and lavage of the joint cavity was performed to allow macroscopic evaluation of hyperaemia and hypertrophy of the synovial membrane. Biopsies were taken at inflamed sites, followed by another lavage to remove blood and debris. Needle arthroscopy of the knee is a simple and easy to perform technique made particularly attractive by the local anaesthesia and the ambulatory setting. It allows good macroscopic evaluation of synovial inflammation and selective sampling of the synovial membrane. Biopsies are suitable for RNA and DNA extraction, bacterial or lymphocyte culture, and cell isolation. Because samples were sometimes too small for representative histology, we switched from a 1.8 mm to a 2.7 mm biopsy forceps with good results. In nearly all cases the arthroscopy was well tolerated. Moreover, some patients reported relief of symptoms and even improvement of mobility after lavage of the inflamed joint. No major complications were noted. It was concluded that needle arthroscopy of the knee is a simple, safe and well-tolerated technique, with promising perspectives as a diagnostic, scientific and possibly therapeutic tool in rheumatic diseases.

Adolescent↗
PubMed1999

Influence of polysulfated polysaccharides on aggrecans synthesized by differentiated human articular chondrocytes.

OBJECTIVE: Synthesis rates of aggrecans by phenotypically stable human articular chondrocytes and the immobilization of these aggrecans in large aggregates have been used as variables reflecting the capability of these cells to restore the extracellular matrix of articular cartilage in vitro. The effects of heparin, chondroitin polysulfate, and xylosan polysulfate on these variables were investigated. METHODS: Human articular chondrocytes were maintained in culture in gelled agarose. After 2 weeks of culture, the media were supplemented for one week with 10 microg/ml each of heparin, chondroitin polysulfate, and xylosan polysulfate. Synthesis of aggrecans was investigated using Na2(35SO4) as a radioactive precursor during the last 24 h of exposure to polysaccharides. Size exclusion chromatography was used to assay the proportions of aggrecans immobilized in aggregates. Native aggrecan aggregates accumulated during culture were liberated in associating conditions by agarase digestion of the artificial agarose matrix and studied by electron microscopy. Hyaluronan synthesis was studied in monolayer cultured chondrocyte derived fibroblasts. The cells were exposed to 3H glucosamine for 24 h after the nutrient media were supplemented with 3 polysaccharides for one week. Size exclusion chromatography was used to assess the length of the hyaluronan filaments. RESULTS: Xylosan polysulfate and chondroitin polysulfate but not heparin significantly increased total 35S incorporation rates in aggrecan. Electron microscopy study of aggrecan aggregates showed that xylosan and chondroitin polysulfate but not heparin significantly increased aggrecan aggregate sizes. The same polysulfated polysaccharides increased the synthesis of high molecular weight hyaluronan by chondrocyte derived fibroblast-like cells. CONCLUSION: Polysulfated polysaccharides significantly increased the synthesis rates and the accumulation of aggrecan in aggregates in the extracellular environment in this in vitro system.

Adult↗
PubMed1998

Bowel inflammation and the spondyloarthropathies.

The concept of spondyloarthropathies gathers together a group of chronic diseases in which not only the locomotor system is involved but also other organs, especially the gastrointestinal tract. In humans, ileocolonoscopic studies demonstrated the presence of inflammatory gut lesions in all the diseases in the spondyloarthropathy group; their presence varied in the different diseases between 20% and 70%. The inflammation could be related to specific disease features in the spondyloarthropathies. Further research supports the hypothesis of subclinical inflammatory bowel disease in some patients with spondyloarthropathy, in which the locomotor inflammation was the only clinical manifestation. The link between gut inflammation and arthropathy has also been demonstrated in animal models, notably the human leukocyte antigen B27 transgenic rats. The temporal relationship between activity and severity of colonic involvement and flares of peripheral arthritis directs treatment of choice. For all forms of enterogenic arthropathies, nonsteroidal anti-inflammatory drugs remain the acute treatment form. Caution is in order, however, because of their possible harmful effects on intestinal integrity, permeability, and even on gut inflammation.

Animals↗
PubMed1998

Distinctive activated cellular subsets in colon from patients with Crohn's disease and ulcerative colitis.

BACKGROUND: Activated lymphocytes are considered to play a pathogenic role in Crohn's disease (CD) and ulcerative colitis (UC), although only a limited fraction of the gut-residing lymphocytes in these diseases may be pathogenetically involved, due to active recruitment from the peripheral circulation. Our aim was to characterize in situ preactivated lymphocytes in inflammatory bowel disease mucosa by expansion with interleukin-2. METHODS: Flow cytometry was performed on T cells expanded from the colon of patients with CD (7), UC (16), and controls (20), with special reference to T-cell activation markers and adhesion molecules. RESULTS: In CD a decrease in alpha4beta7 integrin expression was associated with an increase in alphaEbeta7. In UC a similar increase in alphaEbeta7 was observed. Moreover, L-selectin and CD30 were overexpressed on T helper cells in UC versus CD. CONCLUSION: These findings indicate different immunopathogenic pathways for CD and UC.

Biomarkers↗
PubMed1998

A comparative phenotypical analysis of rheumatoid nodules and rheumatoid synovium with special reference to adhesion molecules and activation markers.

OBJECTIVES: (1) To analyse the in situ expression of adhesion molecules in rheumatoid nodules. (2) To compare the endothelial expression of adhesion molecules in synovial tissue and subcutaneous nodules obtained from the same patients. (3) To compare the expression of adhesion molecules and activation markers on T cell lines from nodules and synovium. METHODS: (1) Immunohistochemical analysis by APAAP technique of E selectin, CD44, ICAM-1, PECAM-1, and VCAM-1 was performed on 10 rheumatoid nodules from seven patients with rheumatoid arthritis (RA); nodules and synovium were simultaneously analysed from three patients. (2) T cell lines were generated from RA nodules (n = 7) and synovium (n = 7) by interleukin 2 expansion, and subsequently characterised by flow cytometry for surface expression of alpha E beta 7, alpha 4 beta 7, CD44, L selectin, LFA-1a, PECAM-1, and CD30. RESULTS: (1) In rheumatoid nodules, the palisading layer strongly stains for ICAM-1 and PECAM-1, but less pronounced for CD44. VCAM-1 staining was usually negative. ICAM-1 is upregulated in the vessels surrounding the central zone of fibrinoid necrosis. The immunohistological picture in different nodules derived from the same patient was similar. (2) The endothelial expression of adhesion molecules is comparable in RA nodules and synovium on an individual level, except for E selectin, which is overexpressed in nodule endothelium. (3) T cell lines from nodules and synovium display similar adhesion molecule profiles. However, the expression of CD30, a T cell activation marker linked with Th2 subsets, is higher in nodules compared with synovium. CONCLUSION: These data support a recirculation hypothesis of T cells between articular and extra-articular manifestations in RA, although the activation state of the T cells in each of these localisations may differ.

Adult↗
PubMed1998

Enrichment of T cells carrying beta7 integrins in inflamed synovial tissue from patients with early spondyloarthropathy, compared to rheumatoid arthritis.

OBJECTIVE: To compare the expression of adhesion molecules on synovial T cells from patients with early spondyloarthropathy (SpA) and rheumatoid arthritis (RA), with special reference to the beta7 integrins alpha4beta7 and alphaEbeta7 in view of their intimate association with intestinal tissue. METHODS: Twenty-five synovial cell lines were generated by interleukin 2 (IL-2) expansion from synovial biopsies of patients with early SpA and RA, obtained from macroscopically inflamed synovial tissue by needle arthroscopy, and subsequently characterized by flow cytometry for CD3, CD4, CD8, L-selectin, CD11a, CD31, CD44, and alpha4beta7 and alphaEbeta7 integrin. RESULTS: In SpA, the beta7 integrin expression was increased, compared to RA. Furthermore, an inverse relation between alpha4beta7 and alphaEbeta7 was present in SpA (r = -0.75, p < 0.02), as on many mucosal T cells. In contrast, an opposite correlation was noted in RA (r = +0.84, p < 0.01), as similarly described on a subset of circulating T cells. CONCLUSION: Increased expression of beta7 integrins was noted on synovial T cell lines from SpA compared to RA, with discriminative correlations between alpha4beta7 and alphaEbeta7. This suggests a different origin of the synovial T cells in these diseases.

Adolescent↗
PubMed1997

Human cartilage glycoprotein-39 as a candidate autoantigen in rheumatoid arthritis.

OBJECTIVE: To identify a cartilage-derived autoantigen that is relevant to the rheumatoid arthritis (RA) disease process. METHODS: A DR4 (DRB1*0401) peptide binding motif was used for the selection of potential self reactive peptides within human cartilage glycoprotein-39 (HC gp-39), a protein that is differentially expressed at the site of chronic inflammation. Synthetic peptides accommodating the motif were tested for binding the RA-associated DR4 (DRB1*0401) molecules. High-affinity binders were then tested for their capacity to stimulate peripheral blood mononuclear cell responses in RA patients or healthy donors. To assess the arthritogenic nature of native HC gp-39, the protein was injected into BALB/c mice. RESULTS: HC gp-39-derived motif-based peptides were selectively recognized by peripheral blood T cells from RA patients. Injection of the intact protein into BALB/c mice resulted in immunity to HC gp-39, which was found to be associated with the development of a chronic, relapsing arthritis. Moreover, inhalation of the protein led to tolerization of antigen-specific T cells and to suppression of HC gp-39-induced arthritis. CONCLUSION: These data indicate that HC gp-39 is a target of the immune response in RA. Consequently, HC gp-39 is a candidate for antigen-specific immunotherapy.

Adipokines↗
PubMed1997

Selection of self-reactive peptides within human aggrecan by use of a HLA-DRB1*0401 peptide binding motif.

The pathogenesis of joint destruction in rheumatoid arthritis remains ill-defined. Joint destruction is thought to be the result of tissue damage mediated by T cells. The mere presence of articular cartilage appears responsible for sustaining chronic synovitis and thereby forwards a role for cartilage-responsive T cells in RA. Taking advantage of the positive DRB1*0401 association with RA susceptibility, we reasoned that T-cell recognition of autoantigens in RA would be restricted by DRB1*0401-encoded molecules. A DR4 (B1*0401) peptide binding motif was used for the identification of putative T-cell epitopes within human aggrecan, a candidate autoantigen. Thirteen peptides were synthesized and tested for binding DRB1*0401 or 0404-encoded molecules. Selected binders were tested for induction of proliferative responses in peripheral blood mononuclear cells from donors carrying the DR4 or DR1 specificity. Both healthy and RA donors responded to human aggrecan-derived peptides, thereby identifying these sequences as T-cell epitopes. Interestingly, responses to aggrecan-derived epitopes were significantly decreased in RA patients compared to controls. This was not due to an overall hyporesponsiveness of RA patients since responses to a recall antigen or mitogen did not differ from controls. The data suggest that in RA, aggrecan-specific T cells may exist in a different stage of activation or may have left the periphery to home to the joint.

Adult↗
PubMed1997

Dominant T cell receptor rearrangements in interleukin 2 expanded lymphocytes from rheumatoid nodules suggest antigen driven T cell activation in situ.

OBJECTIVE: To study at a molecular level the clonality of interleukin 2 (IL-2) expanded T cell lines derived from rheumatoid nodules. Such cell lines were reported in earlier studies with flow cytometry and antiidiotypic monoclonal antibodies (MAb) to be obligoclonal. METHODS: T cell lines were derived from rheumatoid nodules in 2 patients with rheumatoid arthritis (RA) and expanded in medium containing IL-2. Clonality was assessed by flow cytometry and T cell receptor (TCR) idiotype specific Mab and by polymerase chain reaction with primers for V alpha and V beta gene families. Sequence analysis was performed in selected cell lines. RESULTS: In one patient, one cell line was identified with marked overexpression of V alpha 2 cells. Eleven V alpha 2 CDR3 sequences were derived from this cell line: 8 of these clones had an identical CDR3 sequence and one other clone showed a related sequence. Five cell lines derived from a second patient displayed a marked clonal bias to V beta 8 cells. One cell line with strong V beta 8 expression was chosen for further sequence analysis. Twelve V beta 8 sequences were obtained; 11 showed identical CDR3 sequences. CONCLUSION: Molecular analysis of TCR rearrangements in IL-2 expanded T cell lines from rheumatoid nodules strongly suggests that in situ T cell activation is related to classical antigen induced immune activation.

Aged↗
PubMed1996

The gut associated addressins: lymphocyte homing in the gut.

The process of lymphocyte trafficking is mainly regulated by receptors that belong to a group of molecules referred to as adhesion molecules. These molecules can be divided, according to their molecular structure, into three broad families: the integrins; the selectins; and the immunoglobulin superfamily members. The alpha 4 beta 7 integrin is expressed on some lymphocytes with hallmarks of gut tropism. alpha 4 beta 7, among others, serves as a ligand for the mucosal vascular addressin MadCAM-1, which is selectively expressed on mucosal lymphoid organ high endothelial venules and on gut lamina propria venules. It is tempting to believe that related integrin receptors play a crucial role in the recirculation of activated lymphocytes between the gut mucosa and the synovial membrane.

Animals↗
PubMed1996

Lusoria dysphagia in a patient with retroperitoneal fibrosis and Riedel's thyroiditis.

The case history of a 68-year-old woman with progressive dysphagia caused by extrinsic compression of the oesophagus by an aberrant right subclavian artery or arteria lusoria is presented. Previous history mentioned a Riedel's thyroiditis, idiopathic retroperitoneal fibrosis and an aortic sclerosis. The authors want to report the case because it is an example of an association between lusoria dysphagia and retroperitoneal fibrosis, the connective tissue disease responsible for Riedel's thyroiditis, and perhaps, aortic sclerosis. This is the first report of this particular association.

Aged↗