Biomedical subjects

Erik af Klint

Publications and source records attributed to Erik af Klint.

9 recordsLinked to original sources

PubMed2007

Effects of intra-articular corticosteroids and anti-TNF therapy on neutrophil activation in rheumatoid arthritis.

OBJECTIVE: The pro-inflammatory calcium-binding protein S100A12 has been recently ascribed to the novel group of damage associated molecular pattern (DAMP) molecules. Serum levels of S100A12 reflect neutrophil activation during synovial inflammation. The aim of this project was to analyse the effect of intra-articular corticosteroids or systemic anti-TNF treatment on synovial expression and serum levels of S100A12 in rheumatoid arthritis (RA). METHODS: Serum and synovial tissue was obtained from 19 RA patients prior to and 2 weeks after intra-articular corticosteroid therapy. Serum was collected for 34 other patients, and in 14 of these patients synovial tissue was additionally obtained prior to and after 8 weeks of infliximab treatment. The expression of S100A12 was analysed by immunohistochemistry on frozen sections. Levels of S100A12 in serum were determined by ELISA. RESULTS: S100A12 serum levels were elevated in patients with active RA prior to therapy and decreased significantly in patients who responded to treatment in both patient groups, but not in non-responders. The synovial expression of S100A12 was reduced 2 weeks after successful intra-articular corticosteroid treatment. A similar decrease in local expression was found after 8 weeks of successful infliximab treatment. CONCLUSIONS: Successful treatment of RA leads to downregulation of the DAMP protein S100A12. Expression and secretion of S100A12 is rapidly diminished after therapy with intra-articular corticosteroids or infliximab. Taking these findings together, decreasing serum concentrations of S100A12 could reflect alleviated synovial neutrophil activation during successful anti-inflammatory therapy in RA.

Adult↗

PubMed2006

Variability in synovial inflammation in rheumatoid arthritis investigated by microarray technology.

In recent years microarray technology has been used increasingly to acquire knowledge about the pathogenic processes involved in rheumatoid arthritis. The present study investigated variations in gene expression in synovial tissues within and between patients with rheumatoid arthritis. This was done by applying microarray technology on multiple synovial biopsies obtained from the same knee joints. In this way the relative levels of intra-patient and inter-patient variation could be assessed. The biopsies were obtained from 13 different patients: 7 by orthopedic surgery and 6 by rheumatic arthroscopy. The data show that levels of heterogeneity varied substantially between the biopsies, because the number of genes found to be differentially expressed between pairs of biopsies from the same knee ranged from 6 to 2,133. Both arthroscopic and orthopedic biopsies were examined, allowing us to compare the two sampling methods. We found that the average number of differentially expressed genes between biopsies from the same patient was about three times larger in orthopedic than in arthroscopic biopsies. Using a parallel analysis of the tissues by immunohistochemistry, we also identified orthopedic biopsies that were unsuitable for gene expression analysis of synovial inflammation due to sampling of non-inflamed parts of the tissue. Removing these biopsies reduced the average number of differentially expressed genes between the orthopedic biopsies from 455 to 171, in comparison with 143 for the arthroscopic biopsies. Hierarchical clustering analysis showed that the remaining orthopedic and arthroscopic biopsies had gene expression signatures that were unique for each patient, apparently reflecting patient variation rather than tissue heterogeneity. Subsets of genes found to vary between biopsies were investigated for overrepresentation of biological processes by using gene ontology. This revealed representative 'themes' likely to vary between synovial biopsies affected by inflammatory disease.

Aged↗

PubMed2006

Anti-tumor necrosis factor therapy increases synovial osteoprotegerin expression in rheumatoid arthritis.

OBJECTIVE: Treatment of rheumatoid arthritis (RA) with tumor necrosis factor (TNF)-blocking agents, including etanercept and infliximab, has resulted in reductions in the radiographic progression of RA. However, the exact mechanism by which this protection occurs has not been determined. In order to add to such knowledge, we investigated the effect of anti-TNF therapy on the expression of osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) in synovial tissue. METHODS: The expression of OPG and RANKL in synovial biopsy specimens was evaluated by immunohistochemistry. Serial synovial biopsy specimens were obtained from 18 patients with RA, before and after treatment with etanercept (9 patients) or infliximab (9 patients). Biopsy specimens were evaluated by double-blind semiquantitative analysis and image analysis. The in vitro effect of TNF antagonists on the RANKL/OPG expression in osteoblasts and endothelial cells was evaluated by Western blotting. Statistical analysis was performed using Wilcoxon's signed rank test, followed by the Bonferroni correction for multiple comparisons of paired samples. The results of in vitro experiments were evaluated by one-way analysis of variance, with Tukey's post hoc test. RESULTS: Treatment with both infliximab and etanercept increased the expression of OPG in synovial tissue. After 8 weeks of treatment, neither infliximab nor etanercept influenced RANKL expression. In both groups of patients, the RANKL:OPG ratio decreased following therapy. In vitro, both of the TNF antagonists mimicked the in vivo effect, inducing a decrease in the RANKL:OPG ratio in TNF-primed osteoblasts and endothelial cells. CONCLUSION: Therapy with TNF antagonists in RA modulates the OPG/RANKL system, a potential mechanism that could explain the retardation of radiographic damage observed following anti-TNF therapy.

Adult↗

PubMed2006

Intraarticular corticosteroids decrease synovial RANKL expression in inflammatory arthritis.

OBJECTIVE: Intraarticular corticosteroids are frequently used as successful adjuvant therapy for inflammatory arthritides, but little is known about their effects on molecules that regulate bone biology. We undertook this study to investigate the effect of intraarticular corticosteroids on the synovial expression of RANKL and osteoprotegerin (OPG). METHODS: We evaluated RANKL, OPG, and surface marker expression by immunohistochemical methods in synovial knee biopsy samples obtained from 13 patients with inflammatory arthritis before and 2 weeks following intraarticular injection of triamcinolone hexacetonide. We further investigated the effect of dexamethasone (DEX) on RANKL expression by lymphocytes from rheumatoid arthritis synovial fluids (RA SF), using flow cytometric analysis. Finally, we evaluated the in vitro effect of DEX on RANKL and OPG expression in osteoblast-like cells, by Western blotting. RESULTS: Intraarticular corticosteroids induced a decrease in the number of synovial T cells without influencing the number of macrophages, evaluated as both CD68+ and CD163+ cells. This change was paralleled by a decrease of synovial RANKL expression with a concomitant reduction of the RANKL:OPG ratio. DEX down-regulated RANKL expression on lymphocytes derived from RA SF. Moreover, in vitro pretreatment of osteoblast-like cells with tumor necrosis factor favored an antiresorptive effect of DEX treatment through a similar down-regulation of RANKL expression. CONCLUSION: The decrease in inflammation attributed to intraarticular corticosteroids is accompanied by down-modulation of bone destruction markers. These findings offer a rationale for the beneficial effect of corticosteroids on joint erosion in arthritis.

Adrenal Cortex Hormones↗

PubMed2006

Synovial expression of IL-15 in rheumatoid arthritis is not influenced by blockade of tumour necrosis factor.

Blockade of tumour necrosis factor (TNF) is an effective treatment in rheumatoid arthritis (RA), but both non-responders and partial responders are quite frequent. This suggests that other pro-inflammatory cytokines may be of importance in the pathogenesis of RA and as possible targets for therapy. In this study we investigated the effect of TNF blockade (infliximab) on the synovial expression of IL-15 in RA in relation to different cell types and expression of other cytokines, to elucidate whether or not IL-15 is a possible target for therapy, independently of TNF blockade. Two arthroscopies with multiple biopsies were performed on nine patients with RA and knee-joint synovitis before and after three infusions of infliximab (3 mg/kg). Synovial biopsies were analysed with immunohistochemistry for expression of IL-15, TNF, IL-1alpha, IL-1ss and IFN-gamma, and for the cell surface markers CD3, CD68 and CD163. Stained synovial biopsy sections were evaluated by computerized image analysis. IL-15 expression was detected in all synovial biopsies taken at baseline. After infliximab therapy, the expression of IL-15 was increased in four patients and reduced in five. Synovial expression of IL-15 was not correlated with any CD marker or with the presence of any other cytokine. Synovial cellularity was decreased after 8 to 10 weeks of treatment with a significant reduction of the CD68-positive synovial cells, whereas no significant change was seen in the number of CD3-positive T cells and CD163-expressing macrophages. The number of TNF-producing cells in the synovial tissue at baseline was correlated with a good response to therapy. Thus, in this study the synovial expression of IL-15 in RA was not consistently influenced by TNF blockade, being apparently independent of TNF expression in the synovium. Consequently, we propose that IL-15 should remain as a therapeutic target in RA, regardless of the response to TNF blockade.

Antibodies, Monoclonal↗

PubMed2006

Effect of infliximab on mRNA expression profiles in synovial tissue of rheumatoid arthritis patients.

We examined the gene expression profiles in arthroscopic biopsies retrieved from 10 rheumatoid arthritis patients before and after anti-TNF treatment with infliximab to investigate whether such profiles can be used to predict responses to the therapy, and to study effects of the therapy on the profiles. Responses to treatment were assessed using European League Against Rheumatism response criteria. Three patients were found to be good responders, five patients to be moderate responders and two patients to be nonresponders. The TNF-alpha status of the biopsies from each of the patients before treatment was also investigated immunohistochemically, and it was detected in biopsies from four of the patients, including all three of the good responders. The gene expression data demonstrate that all patients had unique gene expression signatures, with low intrapatient variability between biopsies. The data also revealed significant differences between the good responding and nonresponding patients (279 differentially expressed genes were detected, with a false discovery rate < 0.025). Among the identified genes we found that MMP-3 was significantly upregulated in good responders (log2 fold change, 2.95) compared with nonresponders, providing further support for the potential of MMP-3 as a marker for good responses to therapy. An even more extensive list of 685 significantly differentially expressed genes was found between patients in whom TNF-alpha was found and nonresponders, indicating that TNF-alpha could be an important biomarker for successful infliximab treatment. Significant differences were also observed between biopsies taken before and after anti-TNF treatment, including 115 differentially expressed genes in the good responding group. Interestingly, the effect was even stronger in the group in which TNF-alpha was immunohistochemically detected before therapy. Here, 1,058 genes were differentially expressed, including many that were novel in this context (for example, CXCL3 and CXCL14). Subsequent Gene Ontology analysis revealed that several 'themes' were significantly over-represented that are known to be affected by anti-TNF treatment in inflammatory tissue; for example, immune response (GO:0006955), cell communication (GO:0007154), signal transduction (GO:0007165) and chemotaxis (GO:0006935). No genes reached statistical significance in the moderately responding or nonresponding groups. In conclusion, this pilot study suggests that further investigation is warranted on the usefulness of gene expression profiling of synovial tissue to predict and monitor the outcome of rheumatoid arthritis therapies.

Adult↗

PubMed2005

Evidence that anti-tumor necrosis factor therapy with both etanercept and infliximab induces apoptosis in macrophages, but not lymphocytes, in rheumatoid arthritis joints: extended report.

OBJECTIVE: Treatment of rheumatoid arthritis (RA) with tumor necrosis factor (TNF) antagonists is highly effective, but their mechanisms of action are not completely clear. Since anti-TNF therapy induces a decrease in synovial cellularity, this study focused on the modulation of RA synovial apoptosis following treatment with either soluble TNF receptor (etanercept) or TNF chimeric monoclonal antibody (infliximab). METHODS: Apoptosis (TUNEL and active caspase 3 staining) and cell surface markers were evaluated by immunohistochemistry in synovial biopsy samples obtained before and after 8 weeks of treatment with etanercept (12 patients) or infliximab (9 patients). We also determined by flow cytometry the in vitro effect of etanercept and infliximab on apoptosis of RA mononuclear cells derived from the synovial fluid (SF) and peripheral blood (PB). RESULTS: Eight weeks of treatment with etanercept and with infliximab significantly increased synovial apoptosis. This change was accompanied by a significant decrease in the synovial monocyte/macrophage population. The decrease in lymphocyte numbers did not reach statistical significance. In vitro, 24 hours of incubation with either etanercept or infliximab induced apoptosis of the SF monocyte/macrophage population. PB monocyte/macrophages were less susceptible to anti-TNF-mediated apoptosis. No changes in the rate of apoptosis were observed in the lymphocyte population derived from either SF or PB. CONCLUSION: In RA patients, both etanercept and infliximab are able to induce cell type-specific apoptosis in the monocyte/macrophage population. This suggests a potential pathway that would account for the diminished synovial inflammation and the decreased numbers of synovial macrophages evident after TNF blockade.

Adult↗

PubMed2005

Effects of antirheumatic treatments on the prostaglandin E2 biosynthetic pathway.

OBJECTIVE: Microsomal prostaglandin E synthase 1 (mPGES-1) is up-regulated in experimental arthritis and markedly expressed in synovial tissue biopsy samples from patients with rheumatoid arthritis (RA). This study was carried out to determine the effects of tumor necrosis factor (TNF) blockers and glucocorticoids on mPGES-1 and cyclooxygenase (COX) expression, as well as biosynthesis of PGE(2) in rheumatoid joints. METHODS: In vitro effects of TNF blockers and dexamethasone on the PGE(2) biosynthetic pathway were examined in RA synovial fluid mononuclear cells (SFMCs) by flow cytometry. PGE(2) levels in culture supernatants were measured by enzyme immunoassay. Expression of enzymes responsible for PGE(2) synthesis ex vivo was evaluated by immunohistochemistry in synovial biopsy samples obtained from 18 patients before and after treatment with TNF blockers and from 16 patients before and after intraarticular treatment with glucocorticoids. Double immunofluorescence was performed using antibodies against mPGES-1, COX-1, COX-2, and CD163. RESULTS: Double immunofluorescence revealed that mPGES-1 and COX-2 were colocalized in SFMCs as well as in RA synovial tissue cells. The addition of either TNF blockers or dexamethasone suppressed lipopolysaccharide-induced mPGES-1 and COX-2 expression in synovial fluid monocyte/macrophages in vitro and decreased the production of PGE(2). Intraarticular treatment with glucocorticoids significantly reduced both mPGES-1 and COX-2 expression in arthritic synovial tissue ex vivo. The number of COX-1-expressing cells in synovial tissue was also significantly decreased by glucocorticoid treatment. In contrast, neither mPGES-1 nor COX-2 expression in synovial tissue was significantly suppressed by anti-TNF therapy. CONCLUSION: These data are the first to demonstrate the effects of antirheumatic treatments on mPGES-1 expression in RA and suggest that the inhibition of PGE(2) biosynthesis, preferably by targeting mPGES-1, might complement anti-TNF treatment for optimal antiinflammatory results in RA.

Adult↗

PubMed2005

Intraarticular glucocorticoid treatment reduces inflammation in synovial cell infiltrations more efficiently than in synovial blood vessels.

OBJECTIVE: To investigate whether intraarticular (IA) glucocorticoid (GC) therapy diminishes synovial cell infiltration, vascularity, expression of proinflammatory cytokines, and adhesion molecule levels in patients with chronic arthritides. METHODS: Thirty-one patients with chronic arthritides received a single IA injection of triamcinolone hexacetonide to treat active large-joint inflammation. Synovial biopsy specimens were obtained with arthroscopic guidance before and 9-15 days after injection. The presence of T lymphocytes, macrophages, intercellular adhesion molecule 1 (ICAM-1), vascular endothelial growth factor (VEGF), the pan-endothelial marker CD31, and the proinflammatory cytokines interleukin-1alpha (IL-1alpha), IL-1beta, tumor necrosis factor (TNF), and high mobility group box chromosomal protein 1 (HMGB-1) was studied by immunohistochemistry and real-time reverse transcriptase-polymerase chain reaction. RESULTS: IA GC treatment resulted in good clinical response in 29 of 31 joints. After therapeutic intervention, the number of synovial T lymphocytes declined, whereas the number of macrophages remained unchanged. Overall synovial protein expression of TNF, IL-1beta, extranuclear HMGB-1, VEGF, and ICAM-1 was reduced at followup tissue sampling, while no significant effects were observed regarding vascularity. In contrast, expression of IL-1alpha, VEGF, and cytoplasmic HMGB-1 protein in vascular endothelial cells was not affected. GC therapy down-regulated levels of messenger RNA encoding IL-1alpha and IL-1beta, but not TNF or HMGB-1. CONCLUSION: Synovial cell infiltration and proinflammatory cytokine expression were affected in a multifaceted manner by IA GC treatment. Marked reduction of synovial T lymphocytes, TNF, IL-1beta, extranuclear HMGB-1, ICAM-1, and VEGF occurred in association with beneficial clinical effects. Unexpectedly, macrophage infiltration and proinflammatory endothelial cytokine expression remained unchanged. These findings may reflect mechanisms controlling the transiency of clinical improvement frequently observed after IA GC injection.

Adult↗