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‐κB 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.

     

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.     

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.

     

Single and combined inhibition of tumor necrosis factor, interleukin-1, and RANKL pathways in tumor necrosis factor-induced arthritis: effects on synovial inflammation, bone erosion, and cartilage destruction

OBJECTIVE: To investigate the efficacy of single and combined blockade of tumor necrosis factor (TNF), interleukin-1 (IL-1), and RANKL pathways on synovial inflammation, bone erosion, and cartilage destruction in a TNF-driven arthritis model. METHODS: Human TNF-transgenic (hTNFtg) mice were treated with anti-TNF (infliximab), IL-1 receptor antagonist (IL-1Ra; anakinra), or osteoprotegerin (OPG; an OPG-Fc fusion protein), either alone or in combinations of 2 agents or all 3 agents. Synovial inflammation, bone erosion, and cartilage damage were evaluated histologically. RESULTS: Synovial inflammation was inhibited by anti-TNF (-51%), but not by IL-1Ra or OPG monotherapy. The combination of anti-TNF with either IL-1Ra (-91%) or OPG (-81%) was additive and almost completely blocked inflammation. Bone erosion was effectively blocked by anti-TNF (-79%) and OPG (-60%), but not by IL-1Ra monotherapy. The combination of anti-TNF with IL-1Ra, however, completely blocked bone erosion (-98%). Inhibition of bone erosion was accompanied by a reduction of osteoclast numbers in synovial tissue. Cartilage destruction was inhibited by anti-TNF (-43%) and was weakly, but not significantly, inhibited by IL-1Ra, but was not inhibited by OPG monotherapy. The combination of anti-TNF with IL-1Ra was the most effective double combination therapy in preventing cartilage destruction (-80%). In all analyses, the triple combination of anti-TNF, IL-1Ra, and OPG was not superior to the double combination of anti-TNF and IL-1Ra. CONCLUSION: Articular changes caused by chronic overexpression of TNF are not completely blockable by monotherapies that target TNF, IL-1, or RANKL. However, combined approaches, especially the combined blockade of TNF and IL-1 and, to a lesser extent, TNF and RANKL, lead to almost complete remission of disease. Differences in abilities to block synovial inflammation, bone erosion, and cartilage destruction further strengthen the rationale for using combined blockade of more than one proinflammatory pathway.     

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.     

Osteoprotegerin expression in synovial tissue from patients with rheumatoid arthritis,spondyloarthropathies and osteoarthritis and normal controls

OBJECTIVES: To demonstrate the expression of osteoprotegerin (OPG) and receptor activator of nuclear factor kappaB ligand (RANKL) in synovial tissue from rheumatoid arthritis (RA) patients, establish the cell lineage expressing OPG and compare the expression of OPG in RA, spondyloarthropathies, osteoarthritis and normal synovial tissue. METHODS: Synovial biopsy specimens were obtained at arthroscopy from 16 RA and 12 spondyloarthropathy patients with active synovitis of a knee joint, six RA patients with no evidence of active synovitis, 10 patients with osteoarthritis and 18 normal subjects. Immunohistological analysis was performed using monoclonal antibodies (mAb) to detect OPG and RANKL expression. In addition, dual immunohistochemical evaluation was performed with lineage-specific monoclonal antibodies (macrophages, fibroblasts and endothelial cells) and OPG to determine the cell lineages expressing OPG. The sections were evaluated by computer-assisted image analysis and semiquantitative analysis. RESULTS: Two patterns of OPG expression were seen, one exclusively in endothelial cells and one expressed predominantly in macrophages in the synovial lining layer. Both patterns of OPG staining could be blocked with excess recombinant OPG. Endothelial and synovial lining expression of OPG was seen in all synovial tissues except those from patients with active RA. In contrast, RANKL expression was seen predominantly in synovial tissue from patients with active disease, mainly in sublining regions, particularly within areas of lymphocyte infiltration. CONCLUSIONS: OPG expression on macrophage type synovial lining cells as well as endothelial cells is deficient in RA patients with active synovitis, in contrast to that seen in spondyloarthropathy patients with active synovitis. This deficiency in OPG expression in the inflamed joint of RA patients may be important in the development of radiologically defined joint erosions.     

Tumor necrosis factor antagonist therapy and lymphoma development: twenty-six cases reported to the Food and Drug Administration

OBJECTIVE: Etanercept and infliximab are tumor necrosis factor (TNF) antagonists that have been recently approved for the treatment of rheumatoid arthritis (RA) and Crohn's disease (CD). This study was undertaken to investigate the occurrence of lymphoproliferative disorders in patients treated with these agents. METHODS: Relevant data in the MedWatch postmarket adverse event surveillance system run by the US Food and Drug Administration were reviewed. RESULTS: We identified 26 cases of lymphoproliferative disorders following treatment with etanercept (18 cases) or infliximab (8 cases). The majority of cases (81%) were non-Hodgkin's lymphomas. The interval between initiation of therapy with etanercept or infliximab and the development of lymphoma was very short (median 8 weeks). In 2 instances (1 infliximab, 1 etanercept), lymphoma regression was observed following discontinuation of anti-TNF treatment, in the absence of specific cytotoxic therapy directed toward the lymphoma. CONCLUSION: Although data from a case series such as this cannot establish a clear causal relationship between exposure to these medications and the risk of lymphoproliferative disease, the known predisposition of patients with RA and CD to lymphoma, the known excess of lymphoma in other immunosuppressed populations, and the known immunosuppressive effects of the anti-TNF drugs provide a biologic basis for concern and justification for the initiation of additional epidemiologic studies to formally evaluate this possible association.     

High levels of osteoprotegerin and soluble receptor activator of nuclear factor kappa B ligand in serum of rheumatoid arthritis patients and their normalization after anti-tumor necrosis factor alpha treatment

OBJECTIVE: To test the hypotheses that 1) proinflammatory cytokines affect osteoprotegerin (OPG) and soluble receptor activator of nuclear factor kappa B ligand (sRANKL) production and therefore the OPG and sRANKL levels differ in rheumatoid arthritis (RA) patients in comparison with healthy individuals; and 2) anti-tumor necrosis factor alpha (anti-TNF alpha) therapy influences OPG and sRANKL levels. METHODS: Sera were obtained from healthy individuals or RA patients receiving the combination of infliximab and methotrexate. Peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) were isolated from RA patients. Fibroblast-like synoviocytes (FLS) were isolated from synovial tissue obtained at total knee replacement in RA patients. Supernatants from cells stimulated with cytokines were collected after culture in vitro. Concentrations of OPG and sRANKL were determined by enzyme-linked immunosorbent assays. RESULTS: A strong positive correlation between OPG concentration and age was observed in healthy individuals but not in RA patients. The OPG and sRANKL levels were higher in RA patients than in healthy controls. Cultured FLS spontaneously secreted much higher amounts of OPG than PBMCs or SFMCs. Proinflammatory cytokines enhanced OPG production. Anti-TNF alpha treatment resulted in the normalization of serum OPG and sRANKL levels in RA patients without influencing the OPG:sRANKL ratio. CONCLUSION: Although higher serum levels of OPG and sRANKL are present in RA patients than in healthy individuals, the ratio of OPG:sRANKL is similar. There is an age-dependent increase of OPG but not sRANKL levels in healthy subjects. Anti-TNF alpha treatment results in the normalization of elevated levels of OPG and sRANKL in RA patients.     

Variability of RANKL and osteoprotegerin staining in synovial tissue from patients with active rheumatoid arthritis: quantification using color video image analysis

OBJECTIVE: To assess the interpatient, interbiopsy, and intrabiopsy variability of receptor activator of nuclear factor kB ligand (RANKL) and osteoprotegerin (OPG) immunostaining within synovial tissue from rheumatoid knee joints with active synovitis, using digital image analysis. METHODS: Synovial biopsy specimens were obtained from patients with rheumatoid arthritis (RA) and active synovitis. Immunohistologic analysis was performed on frozen synovial tissue biopsy specimens from 6 patients using a monoclonal antibody (Mab) to detect RANKL (626) or OPG (805 or 8051). Patients with a minimum of 4 synovial biopsies were included in the study. Sections were evaluated by computer assisted image analysis to assess between-patient, between-biopsy, and intra-biopsy variability of OPG and RANKL protein expression. The study was designed to deliberately maximize the variability. RESULTS: Computerized image analysis of staining with Mab to RANKL and OPG revealed variance for each antibody across the 3 components of the total variability. CONCLUSION: Our study shows that variability in synovial immunostaining of RANKL and OPG protein is a significant and complex problem. We discuss methods to reduce this variability and suggest that the auspices of OMERACT may be employed to advance the study of synovium in collaborative international studies.     

重组抗肿瘤坏死因子-α人鼠嵌合单克隆抗体对类风湿关节炎患者RANK/RANKL/骨保护素系统的影响

目的 探讨重组抗肿瘤坏死因子(TNF)-α人鼠嵌合单克隆抗体(Infliximab)对类风湿关节炎(RA)患者外周血核因子κB受体因子(RANK)/核因子κB受体活化因子(RANKL)/骨保护素系统的影响.方法 50例经严格筛选的类风湿关节炎(RA)患者按随机分配原则分为2组.一组患者接受Infliximab(3 mg/kg)+甲氨蝶呤治疗;一组患者接受甲氨蝶呤单独治疗作为对照,分别于0、2、6、14周给药.观察0周与18周Infliximab治疗组与对照组患者相关临床指标的改变,对比外周血中RANK、RANKL mRNA表达情况以及血清中骨保护素蛋白水平的变化.用t检验和x2检验做统计学分析.结果 经Infliximab治疗后,在RA患者关节放射成像中,可以观察到骨破坏程度有减缓趋势.与对照组比较,Infliximab治疗组(病史＞1年)患者骨丢失情况得到控制;Infliximab治疗组(0周:80.25;18周:63.2)与对照组(0周:83.37;18周:30.87)患者外周血中RANK、RANKL mRNA表达水平均下降(P＞0.05);与对照组比较,Infliximab可使RA患者外周血骨保护素/RANKL比值下降趋势减缓.虽然,经甲氨蝶呤或Infliximab+甲氨蝶呤治疗后,对照组[0周:(238±15)pg/ml;18周:(118±l0)pg/ml]和Infliximab治疗组[0周:(223±6)pg/ml;18周:(162±6)pg/ml)]患者血清中骨保护素水平均下降(P＞0.05),但Infliximab治疗组患者血清骨保护素下降趋势得以减缓.结论 RA患者经Infliximab联合甲氨蝶呤治疗后,骨破坏受到抑制,其作用机制可能是部分通过对RANK/RANKL/骨保护素系统的调节来行使的.     

Synovial tissue rank ligand expression and radiographic progression in rheumatoid arthritis: observations from a proof-of-concept randomized clinical trial of cytokine blockade

The objective of the study was to evaluate synovial tissue receptor activator of nuclear factor-κβ ligand (RANKL) and osteoprotegerin (OPG) as biomarkers of disease activity, progressive joint damage, and therapeutic response, during cytokine blockade in rheumatoid arthritis (RA). Patients with active RA entered a randomized open-label 12-month study of anakinra 100 mg/day, administered as monotherapy or in combination with pegsunercept 800 μg/kg twice weekly. Arthroscopic synovial tissue biopsies were obtained at baseline, at 4 weeks and at the final time point. Following immunohistochemical staining, RANKL and OPG expression was quantified using digital image analysis. Radiographic damage was evaluated using the van der Heijde modification of the Sharp scoring system. Twenty-two patients were randomized. Baseline expression of RANKL, but not OPG, correlated significantly with baseline CRP levels (r = 0.61, P < 0.01). While a significant reduction in OPG expression following treatment was observed in clinical responders at the final time point (P < 0.05 vs. baseline), RANKL levels did not change, and the RANKL:OPG ratio remained unaltered, even at the highest levels of clinical response. When potential predictors of radiographic outcome were evaluated, baseline RANKL expression correlated with erosive progression at 1 year (r = 0.71, P < 0.01). Distinct, though related, pathophysiologic processes mediate joint inflammation and destruction in RA. Elevated synovial tissue RANKL expression is associated with progressive joint erosion, and may be independent of the clinical response to targeted therapy. The potential therapeutic importance of modulating RANKL in RA is highlighted, if radiographic arrest is to be achieved.     

Modulation of RANKL and osteoprotegerin expression in synovial tissue from patients with rheumatoid arthritis in response to disease-modifying antirheumatic drug treatment and correlation with radiologic outcome

OBJECTIVE: To demonstrate the effect of treatment with disease-modifying agents on the expression of osteoprotegerin (OPG) and RANKL in the synovial tissue from rheumatoid arthritis (RA) patients and to correlate these changes with radiologic damage measured on sequential radiographs of the hands and feet. METHODS: Synovial biopsy specimens were obtained at arthroscopy from 25 patients with active RA (16 of whom had a disease duration <12 months) before and at 3-6-month intervals after starting treatment with a disease-modifying agent. Immunohistologic analysis was performed using monoclonal antibodies to detect OPG and RANKL expression, with staining quantitated using computer-assisted image analysis and semiquantitative analysis techniques. Serial radiographs of the hands and feet were analyzed independently by 2 radiologists and a rheumatologist using the van der Heide modification of the Sharp scoring method. RESULTS: Thirteen patients achieved a low disease state as defined by a disease activity score <2.6 while 19 patients achieved an American College of Rheumatology response >20% after disease-modifying antirheumatic drug (DMARD) treatment. Successful DMARD treatment resulted in an increase in OPG expression and a decrease in RANKL expression at the synovial tissue level, which correlated with a reduction in erosion scores measured on annual radiographs of the hands and feet. CONCLUSION: Successful treatment-induced modulation of OPG and RANKL expression at the synovial tissue level, resulting in a reduction in the RANKL:OPG ratio, is likely to have a significant impact on osteoclast formation and joint damage in patients with active RA.     

Therapy of ankylosing spondylitis. Part II: biological therapies in the spondyloarthritides

Therapeutic options for patients with active and severe spondylarthritis (SpA) have been fairly limited in the past decades. There is now accumulating evidence that biological therapy with agents directed against tumour necrosis factor-alpha (TNF-alpha) is highly efficacious in the spondyloarthritides, especially in ankylosing spondylitis (AS) and psoriatic arthritis (PsA). The TNF blocking agents currently available, infliximab (Remicade), etanercept (Enbrel), and adalimumab (Humira), are approved for the treatment of rheumatoid arthritis (RA) in Europe and the USA. In contrast to rheumatoid arthritis (RA) disease-modifying anti-rheumatic drugs (DMARDs) have limited efficacy in SpA. No DMARDs are available for AS patients with active spinal disease. Thus, for AS patients whose condition is not sufficiently controlled with non-steroidal anti-inflammatory drugs (NSAIDs), therapy with TNF blockers may be considered as a first-line treatment. For infliximab, a dose of 3-5 mg/kg seems to be required, and intervals between 6 and 12 weeks are necessary to suppress disease activity continually. The standard dosage of etanercept is 2 x 25 mg subcutaneously (s.c.) per week. There are very few studies with adalimumab (standard dose in RA 20-40 mg s.c. every 1-2 weeks) in SpA. Infliximab and etanercept are now both approved for AS in Europe. There is some evidence that both agents also work in other SpA, especially in PsA. Withdrawal of long-term therapy in AS patients led to relapses of disease after several months. Less radiographic progression after 2 years of continuous treatment with infliximab compared to conventional therapy has been suggested in a small study. Serious adverse events on anti-TNF therapy have remained rare. However, severe infections, including tuberculosis, have been reported. These can be largely prevented by appropriate screening. The benefits of anti-TNF therapy in AS seem to outweigh these shortcomings.     

Interleukin (IL) 18 stimulates osteoclast formation through synovial T cells in rheumatoid arthritis: comparison with IL1 beta and tumour necrosis factor alpha

OBJECTIVE: To determine whether IL18 has any indirect effects on osteoclastogenesis mediated by T cells in RA synovium, and compare its effects with those of IL1 beta and TNF alpha. METHODS: Resting T cells were isolated from peripheral blood of healthy donors, and stimulated with 2 microg/ml phytohaemagglutinin (PHA) and 0.5 ng/ml IL2 for 24 hours. Synovial T cells were isolated from RA synovial tissue. The levels of soluble receptor activator of the NF-kappa B ligand (RANKL), osteoprotegerin (OPG), IFN gamma, M-CSF, and GM-CSF were determined by ELISA. Membrane bound RANKL expression was analysed by flow cytometry. Commercially available human osteoclast precursors were cocultured with T cells to induce osteoclast formation, which was determined with tartrate resistant acid phosphatase staining and pit formation assay. RESULTS: In PHA prestimulated T cells or RA synovial T cells, IL18, IL1 beta, or TNFalpha increased soluble RANKL production and membrane bound RANKL expression in a dose dependent manner. IL18, IL1 beta, and TNF alpha did not induce M-CSF, GM-CSF, IFN gamma, or OPG production in PHA prestimulated T cells or RA synovial T cells. IL18 increased the number of osteoclasts and bone resorption area on dentine slices in the coculture of human osteoclast precursors with PHA prestimulated T cells or RA synovial T cells; its ability was equivalent to that of IL1 beta, but less potent than that of TNF alpha. In the coculture system, OPG completely blocked osteoclast induction by IL18 or IL1 beta, and greatly inhibited induction by TNF alpha. CONCLUSION: IL18, IL1 beta, or TNF alpha can indirectly stimulate osteoclast formation through up regulation of RANKL production from T cells in RA synovitis; IL18 is as effective as IL1 beta, but less potent than TNF alpha.     

Meta-analysis of the combination of TNF inhibitors plus MTX compared to MTX monotherapy,and the adjusted indirect comparison of TNF inhibitors in patients suffering from active rheumatoid arthritis

This present study was designed to examine (1) whether a combination therapy of TNF (tumor necrosis factor) blockers and methotrexate (MTX) is better than MTX monotherapy, and (2) if the TNF inhibitors such as etanercept, infliximab and adalimumab are all same for treating patients with active rheumatoid arthritis (RA). We performed meta-analysis of a combination therapy of TNF-blockers and MTX compared to MTX monotherapy and we performed adjusted indirect comparison of the TNF-blocking agents for their efficacy and toxicity. Three studies met the inclusion criteria for the analysis. Meta-analysis showed that the combination of MTX with anti-TNF inhibitors was more effective than MTX monotherapy and this indicated that combination therapy of anti-TNF inhibitors and MTX was comparable with MTX monotherapy in terms of withdrawal due to the side effects (RR: 1.05, 95% CI: 0.52–2.09, P = 0.86). The adjusted indirect comparison did not show any differences between infliximab and adalimumab. However, there was a significant difference for clinical efficacy and side effects between etanercept, adalimumab and infliximab. The RRs for achieving ACR20, ACR50 and ACR70 responses and withdrawal due to the side effect in the etanercept group were lower when compared with the adalimumab group. The RR for achieving an ACR20 response in the etanercept group was lower when compared with the infliximab group. The adjusted indirect comparison analysis suggests that the TNF-blocking agents all are not the same with respect to effectiveness and toxicity for the treatment of active RA.     

The abundant synovial expression of the RANK/RANKL/Osteoprotegerin system in peripheral spondylarthritis is partially disconnected from inflammation

OBJECTIVE: Spondylarthritis (SpA) and rheumatoid arthritis (RA) have different patterns of bone damage, with more pronounced bone erosions in RA. The RANK/RANKL/osteoprotegerin (OPG) system plays a central role in bone resorption by promoting the maturation and activation of osteoclasts. To assess the potential role of this system in the distinct bone phenotype, we studied the synovial expression of these mediators in SpA and RA peripheral synovitis. METHODS: Synovial biopsy specimens were obtained from the actively inflamed peripheral joints of 35 patients with SpA and 19 patients with RA. Paired synovial biopsy samples were obtained from 24 patients with SpA after tumor necrosis factor alpha (TNFalpha) blockade. Synovial tissue sections were immunostained for RANKL, OPG, RANK, and TRAP and assessed by semiquantitative scoring and digital image analysis. RESULTS: After extensive validation of the reactivity and specificity of the antibodies, we demonstrated the abundant expression of RANKL and OPG in SpA synovitis. RANKL was expressed by both fibroblast-like synoviocytes and sublining T lymphocytes. RANK-positive osteoclast precursors but no mature TRAP-positive osteoclasts were present in the inflamed tissue. The expression of these mediators was not different between patients with nonpsoriatic SpA, patients with psoriatic SpA, and patients with RA, was not related to the degree of systemic or local inflammation, and was not significantly modulated by highly effective treatment with TNFalpha blockers. Only the subset of patients with the best systemic response to TNFalpha blockade had decreased RANKL expression in the intimal lining layer. CONCLUSION: The relative protection against bone erosions in SpA cannot be explained by qualitative or quantitative differences in the synovial expression of RANKL, OPG, and RANK. The abundant expression of these factors in SpA peripheral synovitis is largely disconnected from systemic and local inflammation.     

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.     

Antitumor necrosis factor therapy for inflammatory bowel disease: a review of agents, pharmacology, clinical results, and safety.

Tumor necrosis factor-alpha (TNFalpha), a proinflammatory cytokine, plays an important role in the pathogenesis of inflammatory bowel disease (IBD). Biotechnology agents including a chimeric monoclonal anti-TNF antibody (infliximab), a humanized monoclonal anti-TNF antibody (CDP571), and a recombinant TNF receptor fusion protein (etanercept) have been used to inhibit TNFalpha activity. Controlled trials have demonstrated efficacy for infliximab in moderately to severely active Crohn's disease (CD) and fistulizing CD sufficient to justify recent U.S. Food and Drug Administration (FDA) approval. Additional trials have been completed in rheumatoid arthritis (RA). Similarly, preliminary controlled trials have suggested efficacy for CDP571 in active CD and RA. Larger controlled trials have demonstrated efficacy for etanercept in RA patients who have failed disease modifying antirheumatic drug (DMARD) therapy leading to FDA approval for RA. Toxicities observed with anti-TNF therapies have included formation of human antichimeric antibodies (HACA) with associated acute and delayed hypersensitivity infusion reactions, human antihuman antibodies (HAHAs), and formation of autoantibodies with rare instances of drug-induced lupus. Several cases of non-Hodgkin's lymphoma also has been described. Future studies should evaluate optimal timing and duration of anti-TNF therapy, the utility of adjuvant medical treatments during anti-TNF therapy, and evaluate long-term safety and efficacy of the various anti-TNF agents.     

Inflammation-Induced Bone Loss: Can it Be Prevented?

Inflammatory synovitis induces profound bone loss and OCLs are the instrument of this destruction. TNF blockers have an established role in the prevention of inflammatory bone loss in RA; however, not all patients respond to anti-TNF therapy and side effects may prevent long-term treatment in others. The B-cell--depleting antibody rituximab and the T-cell costimulation blocker abatacept are emerging as major treatment options for patients who are resistant to anti-TNF [96,97]. Proof-of-concept studies demonstrate that targeting RANK-mediated osteoclastogenesis prevents inflammatory bone loss and clinical application has only just begun. The efficacy of RANKL inhibition has been witnessed in trials of Denosumab, and RANKL-neutralizing antibodies are likely to become the treatment of choice for blocking RANKL in RA [77,78]. A major limitation of RANKL antagonism is that it does not treat synovitis. Therefore, anti-RANKL therapy most likely will be used in the context of MTX therapy. There is uncertainty about the possible extraskeletal adverse effects of long-term effects of long-term RANKL blockade. In particular, anti-RANKL therapy could jeopardize dendritic cell function or survival. The demonstrable role of OCLs in inflammation-induced bone loss also invites a reconsideration of the new BPs for bone protection [98]. Studies of ZA in preclinical models indicate that bone protection is comparable to that afforded by OPG. One possible caveat is that intravenous BPs are linked to jaw osteonecrosis [99], although the incidence is confined mainly to intensive treatment in the oncology setting. Although pulsed PTH stimulated bone formation in arthritic models, it has yet to be proven clinically in the context of powerful OCL inhibition with TNF or RANKL antagonists. With strategies that normalize OCL numbers, clinicians are poised to accomplish effective prevention of inflammation-induced bone loss.     

High levels of interleukin 13 in rheumatoid arthritis sera are modulated by tumor necrosis factor antagonist therapy: association with dendritic cell growth activity

OBJECTIVE: To investigate the physiology of interleukin 13 (IL-13) in rheumatoid arthritis (RA) and the effects of tumor necrosis factor (TNF) antagonists (etanercept) on the distribution of IL-13 in patients with RA. METHODS: We measured cytokine levels in RA sera (pre/post etanercept), RA synovial fluid (SF), osteoarthritis (OA) SF, and normal human sera by ELISA. Detection of IL-13 was not influenced by rheumatoid factor, as revealed in spike recovery and isotype antibody control studies. Biologically active IL-13 in RA SF was studied using dendritic cell (DC) progenitors that develop into mature DC with IL-13 and with neutralizing antibodies to IL-13. The modulation of IL-13 by etanercept was compared to that of IL-6 and monocyte colony stimulating factor (M-CSF). The effect of etanercept on the ability of RA sera to promote DC growth was studied using DC progenitors. RESULTS: IL-13 was increased in RA sera versus normal sera, OA SF, and RA SF. Relative to OA SF and normal sera, RA SF was enriched in IL-13. The IL-13 contained in RA samples was biologically active, prompting DC growth from progenitors. Circulating DC growth activity was strongly reduced by anti-TNF therapy. Whereas decreases in DC growth factors including IL-13 and IL-6 occurred with etanercept therapy and were associated with clinical improvement, concurrent increases in circulating M-CSF (a non-DC, monocyte-specific growth factor) were noted. CONCLUSION: The increase of biologically active IL-13 in RA supports the concept that IL-13 regulates immune cell (including dendritic cell) activity and indicates how the varied anatomical distribution of cytokines may play a role in the RA disease process. The differential regulation of circulating IL-13 and M-CSF levels by TNF antagonists further implies discrete roles in the TNF-cytokine network in RA.