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Biomedical subjects

F De Keyser

Publications and source records attributed to F De Keyser.

At least 55 records · Page 3Linked to original sources
PubMed2001

Specific presence of intracellular citrullinated proteins in rheumatoid arthritis synovium: relevance to antifilaggrin autoantibodies.

OBJECTIVE: To investigate the presence of citrullinated proteins in the synovial membrane of patients with rheumatoid arthritis (RA) and controls, and to analyze a possible relationship with antifilaggrin autoantibody (AFA) reactivity. METHODS: Synovial biopsy samples were obtained from 88 consecutive patients undergoing needle arthroscopy for knee synovitis associated with RA (n = 36), spondylarthropathy (n = 35), osteoarthritis (n = 9), or other diagnoses (n = 8). Tissue sections were stained with 2 different anticitrulline polyclonal antibodies and an antifilaggrin monoclonal antibody (mAb). The phenotype of citrulline-positive cells and the colocalization with affinity-purified AFA were investigated by double immunofluorescence on frozen sections. RESULTS: Studies with the first antibody showed that citrulline is expressed intracellularly in the lining and sublining layers of RA synovial tissue. Staining with the second antibody, monospecific for proteins containing modified citrulline, and with anti-inducible nitric oxide synthetase confirmed the presence of citrullinated proteins rather than free citrulline in the synovium. Citrulline-positive cells were detected in 50% of the RA patients (18 of 36) but in none of the controls (0 of 52). The anticitrulline reactivity colocalized with affinity-purified AFA reactivity, although stainings with the antifilaggrin mAb indicated the absence of filaggrin in the synovium. CONCLUSION: Intracellular citrullinated proteins, which are not recognized by an antifilaggrin mAb, are expressed in RA but not in control synovium. The high specificity of this finding and the colocalization with AFA reactivity boost the interest in citrullinated proteins as possible triggers of autoimmune responses in RA. Moreover, this is the first description of a specific histologic marker for RA synovium.

Adult↗
PubMed2001

The proportion of Th1 cells, which prevail in gut mucosa, is decreased in inflammatory bowel syndrome.

T lymphocytes and their cytokines have an important role in the regulation of immune responses in the gut and in the pathogenesis of intestinal inflammation such as in Crohn's disease. The aim of this study was to analyse the Th1/Th2 cytokine profile (IFN-gamma, IL-2, IL-4 and IL-10) in intraepithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL) in Crohn's disease (CD) and ulcerative colitis (UC) in relation to healthy controls (C). Colonic and ileal biopsy specimens were obtained from controls (n = 13) and patients with CD (n = 32). Colonic biopsies were obtained from patients with UC (n = 11). Intracytoplasmic IFN-gamma, IL-2, IL-4 and IL-10 were determined by flow cytometry after PMA-ionomycin stimulation in IEL and LPL. In colonic LPL, a significant proportional decrease of IFN-gamma and IL-2 producing CD3+ cells was observed in patients with CD and UC compared to controls. In ileal LPL, a similar tendency was found although differences were not significant. In IEL no differences in cytokine profiles could be observed. Flow cytometric analysis of intracytoplasmic cytokines at single cell level showed a proportional decrease of IFN-gamma and IL-2 producing T cells in colonic lamina propria in patients with inflammatory bowel disease.

Adolescent↗
PubMed2001

Detection and identification of antinuclear antibodies (ANA) in a large and consecutive cohort of serum samples referred for ANA testing.

OBJECTIVE: To provide data on (a) the probability of detecting antinuclear antibodies (ANA) in a large and consecutive cohort of serum samples referred for ANA testing and (b) the probability of detecting more specific antinuclear reactivities (anti-DNA and anti-extractable nuclear antigens (anti-ENA)) in serum samples with a positive screening test (indirect immunofluorescence on HEp-2 cells). METHODS: Serum samples from 10 550 consecutive patients sent to the laboratory for ANA detection were analysed. In ANA positive serum samples (23.5% of referred serum samples), ANA were identified by indirect immunofluorescence on Crithidia, by immunodiffusion, and by line immunoassay. Because anti-SSA antibodies were the most frequently identified ANA, sensitively detected by line immunoassay, additional immunoassays were developed to confirm the specificity of the line immunoassay result. RESULTS: At least one fine reactivity could be identified in 21.1% of ANA positive serum samples: anti-dsDNA in 3.2%; anti-ENA (anti-SSA 10.5%, anti-SSB 6.7%, anti-RNP 2.7%, anti-Sm 1.8%, anti-Scl70 1.2%, anti-Jo-1 0.2%) in 15.8%, rRNP and anti-Cenp-B in respectively 0.5% and 4.0%. Multiple reactivities were found in 7.9%. For anti-ENA antibodies, line immunoassay was more sensitive than immunodiffusion (15.4% v 7.7%; p<0.0001). The sensitive detection of anti-SSA antibodies by line immunoassay was confirmed by additional assays. CONCLUSIONS: The data from this analysis are useful in estimating the probabilities of detecting specific ANA. Line immunoassay was shown to be a sensitive test for the detection of anti-ENA antibodies.

Antibodies, Antinuclear↗
PubMed2001

Flow cytometric analysis of gut mucosal lymphocytes supports an impaired Th1 cytokine profile in spondyloarthropathy.

OBJECTIVE: To quantify the fraction of gut mucosal lymphocytes expressing the T helper type 1 (Th1) cytokines, interferon gamma (IFNgamma) and interleukin (IL)2, and the Th2 cytokines, IL4 and IL10, at the single cell level in patients with spondyloarthropathy (SpA) in comparison with healthy controls. METHODS: An improved extraction protocol was used for the enrichment of intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) from colonic and ileal biopsy specimens obtained from patients with SpA (n=20) and healthy controls (n=13). After stimulation with phorbol ester/ionomycin, expression of the intracellular cytokines IFNgamma, IL2, IL4, and IL10 was determined in CD3+, CD3+CD8+ and CD3+CD8- T cells by flow cytometry. RESULTS: In colonic LPLs, a significant decrease in IFNgamma-producing CD3+ cells was observed (p=0.02) in patients with SpA. In the CD3+CD8- subset, the proportion of cells producing IFNgamma and IL2 was decreased in patients with SpA (p=0.021 and p=0.027 respectively). In ileal LPLs, the percentage of IL10-producing CD3+CD8- cells was significantly increased (p=0.046). CONCLUSION: An impaired Th1 cytokine profile is observed in gut mucosal lymphocytes from patients with SpA. This adds to the existing evidence that the gut mucosal immune apparatus is involved in the pathogenesis of SpA.

Adult↗
PubMed2001

Impaired Th1 cytokine production in spondyloarthropathy is restored by anti-TNFalpha.

OBJECTIVES: To evaluate the effect of anti-TNFalpha on the Th1 and Th2 cytokines in patients with spondyloarthropathy (SpA). METHODS: Peripheral blood mononuclear cells (PBMC) were obtained from 20 patients with active SpA treated with infliximab (5 mg/kg). For comparison, PBMC were also obtained from 15 healthy controls and 19 patients with active rheumatoid arthritis (RA). After stimulation with PMA/ionomycin, the intracellular cytokines interleukin (IL)2, IL4, IL10, and interferon (IFN)gamma were determined in CD3+ T cells and in CD3+/CD56+ natural killer (NK) T cells by flow cytometry. RESULTS: At baseline the percentage of T cells positive for IFNgamma (p=0.020) and IL2 (p=0.046) was decreased in patients with SpA compared with healthy controls, while IL10 (p=0.001) was increased. This cytokine profile, confirmed by the mean fluorescence intensities (MFI), was more pronounced in CD3+/CD8- cells and contrasted with higher IL2 production in RA. NK T cells, characterised by high IL4 and IL10 numbers, were also increased in patients with SpA (p=0.017). Treatment with infliximab induced a significant and persistent increase in IFNgamma and IL2 in patients with SpA. Moreover, there was a transient decrease in IL10 and NK T cells in patients with high baseline values, resulting in values comparable with those of healthy controls. This switch in cytokine profile was seen in both the CD3+/CD8- and CD3+/CD8+ subsets. CONCLUSIONS: Before treatment patients with SpA had an impaired Th1 cytokine profile compared with healthy controls and patients with RA. TNFalpha blockade induced restoration of the Th1 cytokines, resulting in a normal cytokine balance. These data confirm the effect of anti-TNFalpha on the immune changes in SpA, and provide insights into the mechanisms involved in TNFalpha blockade.

Adult↗
PubMed2000

Crohn's disease associated with spondyloarthropathy: effect of TNF-alpha blockade with infliximab on articular symptoms.

Four patients with Crohn's disease and spondyloarthropathy were treated with infliximab for treatment-resistant gut inflammation. A substantial improvement in gastrointestinal signs and symptoms was noted, which was accompanied by a rapid reduction in C-reactive protein concentrations. Moreover, all four patients had a significant improvement of axial manifestations and/or peripheral arthritis, related to their spondyloarthropathy. This fast and substantial improvement of the articular manifestations of Crohn's disease after infliximab treatment warrants further investigation of the therapeutic potential of TNF-alpha blockade in other subtypes of spondyloarthropathies.

Antibodies, Monoclonal↗
PubMed2000

Chemical agents and enzymes used for the extraction of gut lymphocytes influence flow cytometric detection of T cell surface markers.

Chemical agents (DTT, EDTA) and enzymes (collagenase, DNAse) are often used for the generation of a single cell suspension from tissue samples. In this study, flow cytometry was used to examine the effect of chemical agents and enzymes on the expression of cell membrane markers of T lymphocytes from tonsils and peripheral blood. Expression of CD4, CD8, CD25, CD38, L-selectin, CD44, alphaEbeta7 and alpha4beta7 were studied. Incubation of lymphocytes with DTT and EDTA resulted in a decrease of CD38, alphaEbeta7 and alpha4beta7 expression. Incubation with collagenase A and DNAse resulted in a decrease of CD25, L-selectin, alphaEbeta7 and alpha4beta7. The results of this study indicate that a careful interpretation is necessary for phenotypic descriptions of lymphocyte populations obtained by enzymatic isolation techniques.

Adolescent↗
PubMed2000

Human cartilage gp-39+,CD16+ monocytes in peripheral blood and synovium: correlation with joint destruction in rheumatoid arthritis.

OBJECTIVE: To investigate the expression of human cartilage (HC) gp-39, a possible autoantigen in rheumatoid arthritis (RA), in peripheral blood and synovium, to characterize its cellular source, and to analyze correlations with clinical features. METHODS: The expression of HC gp-39 in synovium and peripheral blood mononuclear cells (PBMC) was assessed by immunohistochemistry and flow cytometry. Synthesis and secretion were investigated by both reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. RESULTS: PBMC expressing HC gp-39 were increased in RA patients compared with spondylarthropathy patients (P = 0.0029) and with healthy control subjects (P = 0.0013). HC gp-39+ cells were also slightly overrepresented in RA synovium (P = 0.01). In both blood and synovium, HC gp-39+ cells were identified as CD14dim,CD16+ monocytes, a phenotype which can differentiate from classic CD14++ monocytes by maturation in vitro. HC gp-39 messenger RNA was detected in RA synovium and PBMC, and PBMC secreted HC gp-39 in vitro. The number of HC gp-39+ PBMC correlated with serum levels of C-reactive protein (r = 0.39, P = 0.003) and HC gp-39 (r = 0.52, P = 0.014). HC gp-39 expression in RA synovial lining correlated with joint destruction (r = 0.77, P < 0.001). CONCLUSION: CD16+ monocytes, a cellular source of HC gp-39 in vivo, are overrepresented in both RA peripheral blood and synovial tissue. The presence of HC gp-39+ cells in RA synovium is correlated with the degree of joint destruction. These data support a role of these cells in the local autoimmune response that leads to chronic inflammation and joint destruction.

Adipokines↗
PubMed2000

Opportunities for immune modulation in the spondyloarthropathies with special reference to gut inflammation.

The spondyloarthropathies (SpA) are a related group of disorders, characterized primarily by spondylitis, pauci-articular arthritis and enthesitis. The presence of subclinical gut inflammation in patients with SpA ranges from 25 to 75%, depending upon the type of SpA. Several data suggest that the association between gut inflammation and synovitis reflects an etiopathogenetic relationship, and that strategies which interfere with the gut inflammation may also modulate the synovitis. Here we review some standard as well as experimental drugs used in the treatment of patients with inflammatory bowel disease and discuss what is known about their effect on SpA-related locomotor manifestations. For the more experimental drugs, such as cytokines, anticytokines and anti-adhesion compounds, clinical trials in patients with SpA are still very scarce.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Sensitivity of the HEp-2000 substrate for the detection of anti-SSA/Ro60 antibodies.

Anti-SSA/Ro antibodies are the most prevalent type of antinuclear antibody (ANA). Anti-SSA/ Ro-positive sera may recognise two proteins: a 52 kDa (Ro52) and a 60 kDa (Ro60) subunit. We studied the sensitivity for Ro60 detection using the HEp-2000 substrate, which consists of HEp-2 cells transfected with Ro60 cDNA in an anti-SSA/Ro-positive population consecutively identified by double immunodiffusion (DID) with thymus/spleen nuclear extract and line immunoassay (LIA) with recombinant Ro52 and Ro60. One hundred and twenty-seven consecutive anti-SSA/Ro-positive sera defined by DID with thymus/spleen nuclear extract and LIA using recombinant Ro52 and Ro60 were analysed on HEp-2000 and DID with natural Ro60. Of these, 91 were anti-Ro60 positive on LIA and/ or DID with natural Ro60. The HEp-2000 substrate detected 70/91 (sensitivity 77%) and correlated strongest with DID. Most of the missed anti-Ro60-positive sera had high ANA intensity. The substrate did not detect monospecific anti-Ro52 antibodies (sensitivity 9.7%; 3/31). HEp-2000 substrate can therefore be considered a reliable, simple and alternative method for DID in the detection of anti-Ro60 reactivity. Special follow-up should be given to sera with strong ANA patterns in which the SSA/Ro60 staining pattern may be hidden.

Adult↗
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

Comparative study of the synovial histology in rheumatoid arthritis, spondyloarthropathy, and osteoarthritis: influence of disease duration and activity.

OBJECTIVES: To compare the macroscopic and microscopic characteristics of synovial tissue in rheumatoid arthritis (RA), spondyloarthropathy (SpA), and osteoarthritis (OA) after exclusion of possible biases induced by disease duration or activity, or both. METHODS: Synovial biopsy specimens were obtained by needle arthroscopy in patients with early RA (n=16), late RA (n=14), early SpA (n=23), and OA (n=12). Macroscopic and microscopic features were scored on a four point scale and analysed as a function of disease duration (early versus late RA), local and systemic disease activity, and diagnosis. RESULTS: Except for the maximal synovial lining thickness, no significant differences were seen between early and late RA. For disease activity, synovial histology was only weakly correlated with C reactive protein in RA, but seemed to be strongly dependent on effusion of the biopsied joint in all disease groups. After stratification for local disease activity, no disease related differences were found in patients without joint effusion. In contrast, important differences were found between patients with RA and SpA with active joint effusion. Synovial vascularity was macroscopically increased in SpA versus RA (p=0.017). A straight vessel pattern was only seen in RA, while tortuous vessels were preferentially seen in SpA. Vascularity was also microscopically increased in SpA compared with RA (p=0.031), and correlated with the macroscopic vascularity (r(s)=0.36, p=0.036). CD3+ (p=0.008), CD4+ (p=0.008), and CD20+ (p=0.024) lymphocytes were overrepresented in RA compared with SpA. The integrin expression in RA was characterised by a decrease of alphaVbeta3 in the synovial lining (p=0.006) and an increase of alphaVbeta5 in the sublining (p<0.001). CONCLUSIONS: The immune architecture of the synovial membrane is more dependent on local disease activity than on disease duration. Synovium obtained from clinically affected joints shows important histological differences between RA and SpA.

Adolescent↗
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↗
PubMed2000

Effects of a loading dose regimen of three infusions of chimeric monoclonal antibody to tumour necrosis factor alpha (infliximab) in spondyloarthropathy: an open pilot study.

OBJECTIVE: To evaluate the efficacy and safety of a loading dose regimen of three intravenous infusions with infliximab in patients with active spondyloarthropathy. METHODS: A monocentre, open-label pilot study of 21 patients with different subtypes of spondyloarthropathy was conducted. Treatment resistant patients with active disease (fulfilling inclusion criteria) received three infusions of 5 mg/kg infliximab (at weeks 0, 2, and 6). Standard clinical assessments were performed at baseline, and on days 3, 7, and 14, and from then on every two weeks. In patients who fulfilled criteria for ankylosing spondylitis, axial assessment was performed at baseline and on days 14, 42, and 84. RESULTS: In all global assessments (visual analogue scale of patient global assessment, patient pain assessment, doctor global assessment), erythrocyte sedimentation rate, and C reactive protein, a highly significant decrease could be seen already at day 3 (compared with baseline), which was maintained up to day 84. In patients with peripheral disease (n=18), tender and swollen joint count significantly decreased. In patients with axial disease (n=11), functional and disease activity indices significantly improved. Moreover in eight patients with psoriatic arthritis a significant decrease of the psoriasis area and severity index was observed. The treatment was well tolerated in all patients; no significant adverse events were seen. CONCLUSION: In this open-label pilot study of a loading dose regimen of three infusions of chimeric monoclonal antibody to tumour necrosis factor alpha in patients with active spondyloarthropathy, there was a fast and significant improvement of axial and peripheral articular manifestations, without major adverse experiences.

Adult↗
PubMed2000

Occurrence of scleroderma in monozygotic twins.

Familial occurrence of scleroderma is rare and concordance for the disease in twins has been reported exceptionally. We describe 2 female identical twin pairs concordant for scleroderma. The first twin pair was diagnosed with the systemic form of scleroderma, the second pair with the localized form.

Child↗
PubMed2000

Spondyloarthropathy is underestimated in inflammatory bowel disease: prevalence and HLA association.

OBJECTIVE: To determine the overall prevalence of spondyloarthropathy (SpA) among patients with inflammatory bowel disease (IBD) [Crohn's disease (CD) and ulcerative colitis (UC)]. METHODS: One hundred three consecutive patients with IBD from a gastroenterology unit were questioned and examined for SpA symptoms. Patients previously diagnosed with SpA were excluded. All patients were questioned and examined for SpA symptoms such as inflammatory back pain, joint swelling, enthesitis, and psoriasis or a specific family history. Radiographs were taken of all sacroiliac joints. HLA loci A, B, C, and DR were determined in all patients. RESULTS: Thirty-nine percent of the patients with IBD had clinical articular manifestations: 30% had inflammatory back pain, 10% had synovitis, and 7% had a peripheral enthesopathy. The majority (90%) of patients with rheumatic complaints fulfilled the classification criteria for SpA and 10% fulfilled the criteria for ankylosing spondylitis. Asymptomatic sacroiliitis was found in an additional 18% of the patients. Moreover, sacroiliitis, symptomatic or asymptomatic, was related to the disease duration. HLA-B27 conferred an additional risk for inflammatory low back pain in patients with IBD. CONCLUSION: Articular involvement in IBD can be classified as SpA. The appearance of SpA occurs irrespective of the extent of the bowel disease. Moreover, asymptomatic sacroiliac involvement is a common manifestation in IBD and it is related to disease duration, suggesting evidence for a related pathogenic mechanism.

Aged↗