Complement activation in patients with rheumatoid arthritis mediated in part by C‐reactive protein

Objective

Complement activation in patients with rheumatoid arthritis (RA) is considered to be triggered by immune complexes. Recently, it was shown that C‐reactive protein (CRP) can activate the complement system in vivo. We therefore hypothesized that part of the complement activation in RA is due to CRP. The aim of this study was to investigate CRP‐mediated complement activation in RA, and to assess its correlation with disease activity.

Methods

Complexes between CRP and the activated complement components C3d (C3d–CRP) and C4d (C4d–CRP), which reflect CRP‐mediated complement activation, as well as the overall levels of activated C3 and C4 were measured in the plasma of 107 patients with active RA and 177 patients with inactive RA. Inactive RA was defined according to the American College of Rheumatology criteria for clinical remission. Disease activity was assessed by the modified Disease Activity Score (DAS28).

Results

Plasma levels of C3d–CRP and C4d–CRP were increased in the majority of the patients, and were significantly higher in patients with active disease versus those with inactive RA (P < 0.001). In patients with active RA, the plasma concentrations of C3d–CRP and C4d–CRP correlated significantly with the DAS28 (Spearman's rho 0.61 and 0.55, respectively; P < 0.001), whereas these correlations were less pronounced in patients with inactive RA (Spearman's rho 0.28 [P < 0.001] and 0.25 [P = 0.001], respectively). Levels of activated C3 and C4 were also increased in the majority of the patients, particularly in patients with active RA.

Conclusion

Part of the activation of complement in RA is mediated by CRP and is correlated with disease activity. We suggest that this activation is involved in the pathogenesis of RA.

     

Evaluation of classical complement pathway activation in rheumatoid arthritis: measurement of C1q-C4 complexes as novel activation products

OBJECTIVE: Novel activation products that are stable and minimally susceptible to in vitro artefacts have recently been described in the classical complement pathway. The present study assessed circulating levels of these products, i.e., covalent complexes between the recognition molecule of the classical pathway (C1q) and activated C4, in plasma samples from patients with rheumatoid arthritis (RA) to establish the relationship between these levels and the clinical and immunologic parameters in these patients. METHODS: C1q-C4 levels were measured in plasma samples from 41 patients with active RA and 43 patients with inactive RA. These levels were related to other complement activation products and to disease activity according to the Disease Activity Score in 28 joints (DAS28), using Spearman's rank correlations. RESULTS: C1q-C4 plasma levels were significantly higher in patients with active RA as compared with patients with RA in clinical remission (median 3.3 arbitrary units [AU], range 0.4-13.4 versus 1.7 AU, range 0.2-5.5; P=0.0001), suggesting that activation of the classical complement pathway reflects disease activity. This was supported by a significant correlation between C1q-C4 levels and the DAS28 (r=0.398, P=0.0002). Levels of other complement activation products, such as activated C4 (C4b/c), were also significantly elevated in patients with active disease compared with patients with inactive disease (P=0.03), and were correlated with C1q-C4 levels (r=0.329, P=0.002). Levels of C1q-C4 complexes were higher in synovial fluid samples than in plasma samples from the 4 patients tested. CONCLUSION: Systemic complement activation via the classical pathway in patients with RA correlates with disease activity. These results indicate that C1q-C4 complexes may be used as a biomarker for RA.     

Infliximab treatment reduces complement activation in patients with rheumatoid arthritis

BACKGROUND: Tumour necrosis factor (TNF) blocking agents decrease C reactive protein (CRP) levels in rheumatoid arthritis (RA). It has been shown that CRP may contribute to complement activation in RA. OBJECTIVE: To assess the effect of intravenous infliximab treatment on complement activation, especially that mediated by CRP, in RA. METHODS: 35 patients with active RA (28 joint count Disease Activity Score (DAS28) >4.4) were treated with intravenous injections of infliximab (3 mg/kg, at weeks 0, 2, 6, 14, and 22). Clinical response and plasma levels of complement activation products, of CRP and of CRP-complement complexes, which are specific markers for CRP mediated complement activation, were assessed at the indicated time points up to 22 weeks. The relationship between CRP and CRP-complement complexes was analysed by paired t test between two time points and by generalised estimated equation, to test differences of variables over time. RESULTS: At 2 weeks after the first dose, infliximab significantly reduced overall C3 and C4 activation and plasma levels of CRP and CRP-complement complexes were also significantly reduced at this time point. The effects of infliximab on CRP and complement continued throughout the observation period and were more pronounced in patients with a good response to infliximab treatment. CONCLUSION: Treatment with infliximab decreases plasma levels of CRP and CRP dependent complement activation products and concomitantly may reduce complement activation in RA. Complement activation may be among the effector mechanisms of TNF in RA.     

Evaluation of classical complement pathway activation in rheumatoid arthritis: Measurement of C1q–C4 complexes as novel activation products

Objective

Novel activation products that are stable and minimally susceptible to in vitro artefacts have recently been described in the classical complement pathway. The present study assessed circulating levels of these products, i.e., covalent complexes between the recognition molecule of the classical pathway (C1q) and activated C4, in plasma samples from patients with rheumatoid arthritis (RA) to establish the relationship between these levels and the clinical and immunologic parameters in these patients.

Methods

C1q–C4 levels were measured in plasma samples from 41 patients with active RA and 43 patients with inactive RA. These levels were related to other complement activation products and to disease activity according to the Disease Activity Score in 28 joints (DAS28), using Spearman's rank correlations.

Results

C1q–C4 plasma levels were significantly higher in patients with active RA as compared with patients with RA in clinical remission (median 3.3 arbitrary units [AU], range 0.4–13.4 versus 1.7 AU, range 0.2–5.5; P = 0.0001), suggesting that activation of the classical complement pathway reflects disease activity. This was supported by a significant correlation between C1q–C4 levels and the DAS28 (r = 0.398, P = 0.0002). Levels of other complement activation products, such as activated C4 (C4b/c), were also significantly elevated in patients with active disease compared with patients with inactive disease (P = 0.03), and were correlated with C1q–C4 levels (r = 0.329, P = 0.002). Levels of C1q–C4 complexes were higher in synovial fluid samples than in plasma samples from the 4 patients tested.

Conclusion

Systemic complement activation via the classical pathway in patients with RA correlates with disease activity. These results indicate that C1q–C4 complexes may be used as a biomarker for RA.

     

Functional disability in relation to radiological damage and disease activity in patients with rheumatoid arthritis in remission

OBJECTIVE: To investigate the relationship between functional disability, disease activity and radiological damage in patients with rheumatoid arthritis (RA) in remission. METHODS: One hundred and eighty-six patients with RA in remission or with low disease activity were studied. The following variables were assessed at one time point: joint count, visual analog scale for pain, functional disability, i.e., health assessment questionnaire (HAQ) score, radiological joint damage as assessed by radiographs of hands and feet and scored according the Sharp-van der Heijde method, and presence of comorbidity. Disease activity was expressed as the disease activity score (DAS). Correlations were calculated by Spearman's rho coefficient of correlation. In addition, variables associated with the score were analyzed by logistic regression. RESULTS: The median HAQ score was 0.25 [interquartile (IQR) range 0-0.75] and the median DAS was 1.0 (IQR 0.7-1.5). Of the 186 RA patients included, 82% were in remission according to the DAS. The median joint damage as assessed by the Sharp-van der Heijde score was 21 (IQR 9-74). Functional disability was significantly correlated with pain (rho 0.48, p < 0.001), disease activity (rho 0.42; p < 0.001), disease duration (rho 0.39; p < 0.001), radiographic joint damage (rho 0.37; p < 0.001), and age (rho 0.19; p = 0.01). In a logistic regression model functional disability was independently related to presence of pain, disease activity, radiographic joint damage and disease duration in decreasing order of strength, but not to age. sex and co-morbidity. CONCLUSION: Patients with RA who are in remission might experience minimal functional disability and radiographic joint damage. Functional disability in RA patients in remission is most strongly related to the presence of pain and in lesser extent to disease activity, radiographic joint damage, and disease duration.     

Complement activation induced by ischemia-reperfusion in humans: a study in patients undergoing partial hepatectomy

BACKGROUND/AIM: Activation of the complement system is induced by ischemia-reperfusion (I/R) in animal models. Whether I/R also induces complement activation in humans is not known. Here, we investigated complement activation in patients undergoing major liver resection. METHODS: In 11 of 17 patients, the hepatoduodenal ligament was clamped, making the liver transiently ischemic (HEMI+; mean ischemia time, 42 +/- 18 min); 6 patients were operated without clamping (HEMI-). Activation at plasma level (circulating activation products) was studied in blood samples collected prior to surgery and 5, 24 and 48 h thereafter. Parameters analyzed were C4b/c and C3b/c, C4d and C3d, C3a, as well as complexes between complement and C-reactive protein (CRP), which reflect CRP-induced complement activation. Activation at tissue level (C3 and C4 fixation) was studied in liver biopsies obtained before and after resection. RESULTS: In plasma, post-operative levels of C4b/c and C3b/c were not different from baseline levels in both groups. Mean plasma levels of C4b/c and C3b/c were significantly decreased at 24 h post-surgery in the HEMI+ group (p=0.02 and p=0.07). At the same time, levels of C4d-CRP and C3d-CRP were significantly increased (p<0.01 for both parameters). At tissue level, activated complement fragments were observed intracellularly in some pericentral hepatocytes. In I/R livers, large numbers of hepatocytes were positively stained for all complement activation products. CONCLUSIONS: Our data show that in situ complement activation via the classical route occurred during liver resection and that ischemia and/or reperfusion may have contributed to activation. Levels of complement activation products in the circulation were low, showing that transient ischemia had no severe influence on systemic complement activation, suggesting a locally contained response.     

Activated complement components and complement activator molecules on the surface of cell-derived microparticles in patients with rheumatoid arthritis and healthy individuals

OBJECTIVES: In vitro, microparticles can activate complement via the classical pathway. If demonstrable ex vivo, this mechanism may contribute to the pathogenesis of rheumatoid arthritis (RA). We therefore investigated the presence of activated complement components and complement activator molecules on the surface of cell-derived microparticles of RA patients and healthy individuals. METHODS: Microparticles from synovial fluid (n = 8) and plasma (n = 9) of 10 RA patients and plasma of sex- and age-matched healthy individuals (n = 10) were analysed by flow cytometry for bound complement components (C1q, C4, C3) and complement activator molecules (C-reactive protein (CRP), serum amyloid P component (SAP), immunoglobulin (Ig) M, IgG). RESULTS: Microparticles with bound C1q, C4, and/or C3 were abundant in RA synovial fluid, while in RA and control plasma much lower levels were present. Microparticles with bound C1q correlated with those with bound C3 in synovial fluid (r = 0.961, p = 0.0001), and with those with bound C4 in plasma (RA: r = 0.908, p = 0.0007; control: r = 0.632, p = 0.0498), indicating classical pathway activation. In synovial fluid, microparticles with IgM and IgG correlated with those with C1q (r = 0.728, p = 0.0408; r = 0.952, p = 0.0003, respectively), and in plasma, microparticles with CRP correlated with those with C1q (RA: r = 0.903, p = 0.0021; control: r = 0.683, p = 0.0296), implicating IgG and IgM in the classical pathway activation in RA synovial fluid, and CRP in the low level classical pathway activation in plasma. CONCLUSIONS: This study demonstrates the presence of bound complement components and activator molecules on microparticles ex vivo, and supports their role in low grade complement activation in plasma and increased complement activation in RA synovial fluid.     

The value of complement measurements in the assessment of lupus activity

The complement system was studied prospectively in 29 patients, predominantly renal (25), with systemic lupus erythematosus (SLE) to examine the value of complement assays in the distinction between active and inactive disease. Disease activity was evaluated primarily by clinical, biochemical and histological parameters which were obtained at the time of assessment. Fourteen patients had active disease, as assessed by clinical and laboratory criteria. Clq, C4, C4a, C2, C3, C3a, C5, total haemolytic activity (CH50) and complement inhibitors were measured in each patient. The ratios of C4a:C4 and C3a:C3 were also calculated.
Values for all components except C5 were different between control subjects and active patients while only CH50 was different between inactive patients and controls. All parameters except C4a:C4 and C5 were different between active and inactive patients. There was a highly significant difference in the number of active patients with reduced levels of C2, C3 and C3a:C3 compared to inactive patients (i.e. p < 0.001) whereas lesser or no difference was observed for other parameters. The concentration of complement inhibitors was elevated in both groups.
We conclude that, among readily available complement parameters, C2 and C3 provide the best assessment of disease activity in patients with SLE.     

Amino-terminal fragment of the prohormone brain-type natriuretic peptide in rheumatoid arthritis

OBJECTIVE: Increased concentrations of N-terminal pro-brain natriuretic peptide (NT-proBNP) are associated with cardiovascular morbidity and mortality, but little is known about their relationship to chronic inflammation. Patients with rheumatoid arthritis (RA) have chronic inflammation, increased arterial stiffness, and accelerated coronary atherosclerosis. This study was undertaken to test the hypothesis that NT-proBNP concentrations are elevated in patients with RA and are associated with coronary artery calcification and markers of inflammation. METHODS: In 159 patients with RA (90 with early RA and 69 with longstanding RA) without heart failure and 88 control subjects, serum concentrations of NT-proBNP, interleukin-6 (IL-6), and tumor necrosis factor alpha (TNFalpha) were measured and coronary calcification was assessed. Associations between NT-proBNP levels and the other parameters were investigated. RESULTS: NT-proBNP concentrations were elevated in patients with longstanding RA (median 142.8 pg/ml [interquartile range 54.8-270.5]) and those with early RA (median 58.1 pg/ml [interquartile range 19.4-157.6]) compared with controls (18.1 [3.2-46.0]) (P < 0.001). In patients with RA, NT-proBNP concentrations were associated with age (rho = 0.35, P < 0.001), levels of IL-6 (rho = 0.33, P < 0.001), TNFalpha (rho = 0.23, P = 0.003), and C-reactive protein (CRP) (rho = 0.21, P = 0.01), coronary calcium score (rho = 0.30, P < 0.001), systolic blood pressure (rho = 0.30, P < 0.001), and disease activity (rho = 0.29, P < 0.001). After adjustment for age, race, and sex, the associations between NT-proBNP concentrations and disease activity, TNFalpha, IL-6, and CRP remained significant, but those with systolic blood pressure and coronary calcium score were attenuated. CONCLUSION: NT-proBNP concentrations are increased in patients with RA without clinical heart failure and may indicate subclinical cardiovascular disease and a chronic inflammatory state.     

2-D speckle-tracking assessment of left and right ventricular function in rheumatoid arthritis patients with and without disease activity

Objectives

Disease activity has been considered as independent cardiovascular risk factor in rheumatoid arthritis (RA) patients. We aimed to evaluate the effect of RA disease activity on left ventricular (LV) and right ventricular (RV) functions by speckle tracking echocardiography (STE).

Usefulness of detection of complement activation products in evaluating SLE activity

Complement activation products, such as C1rs-C1inh, specific for the activation of the classical pathway, C3b(Bb)P, specific for the activation of the alternative pathway and SC5b-9, specific for common terminal pathway of the complement cascade, were measured in healthy donors and in patients with clinically active and inactive systemic lupus erythematosus (SLE). Plasma levels of C3b(Bb)P and SC5b-9 were moderately, those of C1rs-C1inhibitor (C1rs-C1inh) were markedly elevated in patients with clinically inactive SLE, compared with healthy controls. The difference between active and inactive stages of the disease was best reflected by C3b(Bb)P plasma concentration (P<0.001), which also showed the highest correlation with the SLEDAI (Rs=0.41 P<0.001) and which was the most useful in distinguishing active and inactive sample pairs as well. The difference between SC5b-9 levels in the active and inactive stages was also significant (P=0.007), while that of C1rs-C1inh did not differ significantly (P=0.136). The correlation of the SLEDAI with SC5b-9 was 0.3 (P=0.015), while with C1rs-C1inh it was 0.21 (P=0. 089). These findings suggest that the measurement of complement activation products, especially that of the alternative pathway, are sensitive markers of the activity of SLE and can be used for clinical purposes.     

Platelet and leucocyte activation in childhood sickle cell disease: association with nocturnal hypoxaemia

We hypothesized that vaso-occlusive events in childhood sickle cell disease (SCD) may relate to inflammatory cell activation as well as interactions between sickle erythrocytes and vascular endothelium. Peripheral blood was examined from 24 children with SCD, of whom 12 had neurological sequelae and seven had frequent painful crises, and 10 control subjects. Platelet (CD62P and CD40L expression) and granulocyte (CD11b expression) activation and levels of platelet-erythrocyte and platelet-granulocyte complexes were determined by flow cytometry. Platelets (P = 0.019), neutrophils (P = 0.02) and monocytes (P = 0.001) were more activated and there were increased platelet-erythrocyte complexes (P = 0.026) in SCD patients compared with controls. Platelet-granulocyte complexes were not raised. There were no differences between the different groups of SCD. As hypoxia activates monocytes, platelets and endothelial cells and causes sickling of SCD erythrocytes, we also investigated 20 SCD patients with overnight pulse oximetry. Minimum overnight saturation correlated with the level of platelet-erythrocyte complexes (Spearman's rho -0.668, P < 0.02), neutrophil CD11b (Spearman's rho -0.466, P = 0.038) and monocyte CD11b (Spearman's rho -0.652, P = 0. 002). These findings provide important clues about the mechanism by which SCD patients may become predisposed to vaso-occlusive events.     

Modification of pro- and antiinflammatory cytokines and vascular-related molecules by tumor necrosis factor-a blockade in patients with rheumatoid arthritis

OBJECTIVE: Analysis of serum concentrations and modifications of tumor necrosis factor-a (TNF-a), its soluble receptors (TNFR), interleukin 10 (IL-10), and vascular related molecules [soluble vascular cell adhesion molecule 1 (sVCAM-1), vascular endothelial growth factor (VEGF)] after therapy with methotrexate (MTX) and anti-TNF (infliximab) in patients with rheumatoid arthritis (RA). METHODS: Thirty-six patients with RA and 20 healthy controls were included. Patients had been orally taking a stable dose of MTX of at least 12.5 mg/week for a minimum of 6 months before inclusion in the study. Twenty-five patients had shown a clinical response to MTX (MTX Group). The other 11 had shown an unsatisfactory response and presented with active RA; they were selected for additional treatment with infliximab (MTX + IFM Group). Disease activity score (DAS28), hemoglobin concentration, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum levels of TNF-a, soluble TNFR, IL-10, sVCAM-1 and VEGF were determined at baseline and prior to every infusion of infliximab (3 mg/kg) at 2, 6, 14, 22, and 30 weeks. RESULTS: Although serum levels of TNF-a were similar in patients and controls, patients showed significantly higher concentrations of both soluble TNFR (sTNFR55 and sTNFR75), IL-10, sVCAM-1, and VEGF than healthy individuals. Significantly higher levels of sVCAM-1 and VEGF, but not of the other tested molecules, were detected in those with active disease. After infliximab treatment (MTX + IFM Group) there was a significant decrease in DAS28 and modified Health Assessment Questionnaire scores and ESR and CRP levels. Serum concentration of VEGF showed a significant decrease after infliximab, with levels comparable to those of patients with inactive RA, although VEGF continued to present higher values than in healthy controls. CONCLUSION: Increased levels of vascular related molecules sVCAM-1 and VEGF are serum markers of active RA. The absence of normalization of levels of these molecules in patients with inactive RA could be one of the reasons response to therapy is only temporary.     

Quality of life and economic impact of switching from established infliximab therapy to adalimumab in patients with rheumatoid arthritis

OBJECTIVE: To evaluate the quality of life and economic impact of switching therapy from infliximab to adalimumab in patients with rheumatoid arthritis (RA). METHODS: In this open-label study, patients demonstrating a clinical response to infliximab were switched to treatment with adalimumab and followed for 16 weeks. Both generic (Health Assessment Questionnaire and Short Form 36 Physical Component Summary and Mental Component Summary) and specific (Rheumatoid Arthritis Quality of Life questionnaire) assessment instruments of physical function and of quality of life were employed. An economic analysis of treatment-related costs was also performed. Disease activity was assessed by the composite 28-joint count Disease Activity Score (DAS28). C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were measured as acute phase markers. RESULTS: Nineteen patients were enrolled and completed the study. No changes in functional and quality-of-life measures were observed. One-year extrapolation data showed potential reductions in costs following switching to adalimumab that could be attributed primarily to reductions in patient- and staff-related costs. Safety and tolerability were similar for both treatments. Although there was a significant reduction in DAS28 (P < 0.005) and CRP (P < 0.001) after switching to adalimumab, there were no significant changes in individual DAS28 components, including swollen and tender joint counts and ESR. CONCLUSIONS: A switch from infliximab to adalimumab in patients with RA who have responded to infliximab is a feasible, well-tolerated treatment option, with the potential for direct and indirect economic advantages.     

Increased platelet activation markers in rheumatoid arthritis: Are they related with subclinical atherosclerosis?

Atherosclerotic cardiovascular mortality is increased in rheumatoid arthritis (RA) patients. We evaluated the association of inflammatory response with platelet, endothelial, coagulation activation parameters; and subclinical atherosclerosis in RA patients. We included 27 RA patients (21 female; six male) and 19 healthy subjects (14 female; five male). Disease activity score (DAS28) in RA patients was calculated; and patients were divided into two groups as active and inactive. Flow cytometry was used to determine platelet CD62P expression, platelet microparticles (PMP), platelet-monocyte (PMC) and platelet-neutrophil complexes (PNC). Plasma E-selectin, thrombin-antithrombin (TAT) complex, and serum sCD40L levels were determined by ELISA. The intima-media thickness (IMT) of carotid arteries was determined by B-mode ultrasonography. In RA patients, platelet CD62P expression (p < 0.001), PMC (p = 0.037) and sCD40L (p < 0.001) levels were increased when compared to the control group. PNC (p = 0.07) and TAT levels (p = 0.1) were non-significantly higher, and PMP level (p = 0.075) was nonsignificantly lower in RA patients. Soluble E-selectin level was significantly higher in the active RA group than in the inactive RA group (p = 0.009). There was no correlation between carotid IMT and activity markers, the evaluated parameters (p > 0.05).The increase in markers of active platelets, CD62P and sCD40L, and PMC levels might be associated with the increased cardiovascular mortality in RA. Nevertheless, none of these parameters were associated with carotid IMT: this suggests that one cross-sectional value might not be a good marker for atherosclerosis.     

Evaluation of disease activity in rheumatoid arthritis by Routine Assessment of Patient Index Data 3 (RAPID3) and its correlation to Disease Activity Score 28 (DAS28) and Clinical Disease Activity Index (CDAI): an Indian experience

Serial objective assessment of disease activity in rheumatoid arthritis (RA) is imperative to achieve remission. Routine Assessment of Patient Index Data 3 (RAPID3), an index without formal joint counts, appears attractive for evaluation of disease activity in RA patients in a busy clinical setting. This study aims to evaluate correlation and agreement of RAPID3 with Disease Activity Score 28 (DAS28) and Clinical Disease Activity Index (CDAI) in RA patients. All patients completed a Multidimensional Health Assessment Questionnaire (MDHAQ) at each visit. A physician/assessor 28-joint count and erythrocyte sedimentation rate were completed in 200 literate patients with RA to score DAS28, CDAI, and RAPID3. RAPID3 includes the three MDHAQ patient self-report RA core dataset measures for physical function, pain, and patient global estimate. Proposed RAPID3 (range, 0?C30) severity categories of high (>12), moderate (6.1?C12.0), low (3.1?C6.0), and near remission (??3) were compared to DAS28 (0?C10) activity categories of high (> 5.1), moderate (3.21?C5.1), low (2.61?C3.2), and remission (?? 2.6), and CDAI (0?C76) categories of >22, 10.1?C22.0, 2.9?C10.0, and ??2.8. Statistical significance was analyzed using Spearman correlations, cross-tabulations, and kappa statistics. Comparison of RAPID3 with DAS28 and CDAI indicated Spearman rank-order correlation coefficients for DAS28 with RAPID3 of 0.910, and for CDAI with RAPID3 of 0.907, all highly significant (P?<?0.001). There was substantial agreement between RAPID3 and DAS28 (kappa value?=?0.634, P?<?0.001) and also between RAPID3 and CDAI (kappa value?=?0.690, P?<?0.001). Overall, 89?C94?% of patients who met DAS28 or CDAI moderate/high activity criteria met similar RAPID severity criteria and 84?C88?% who met DAS28 or CDAI remission/low activity criteria also met similar RAPID criteria. RAPID3 scores provide similar quantitative information to DAS28 and CDAI, and hence, is an informative index for evaluation of disease activity in RA in busy clinical settings.     

The value of changes in CRP and ESR for predicting treatment response in rheumatoid arthritis

Aim: During treatment of rheumatoid arthritis (RA) the serum C‐reactive protein (CRP) and erythrocyte sedimentation rate (ESR) decrease concurrent with clinical improvement. The aim of this paper is to investigate whether changes of these parameters could predict treatment response. Methods: Patients with active RA, requiring disease‐modyfying antirheumatic drugs were entered into the study. Serum CRP and ESR were assessed at baseline and 24 weeks after the treatment. Response to treatment was assessed by the RA Disease activity Score 28 (DAS28) and DAS28‐CRP response criteria. In statistical analysis the agreement between changes of CRP and ESR at the first stage of the treatment and DAS28/DAS28‐CRP were determined as ‘good’, ‘moderate’ and ‘none’ responses. The relationship between changes in CRP and DAS28‐CRP, ESR and DAS28 were also determined and compared. Results: Sixty‐six patients with active RA entered the study. The mean age was 50 ± 18 years and the mean disease duration was 4.9 ± 5.8 years. After an average period of 24 weeks, 51 patients met the DAS28 and 49 patients met the DAS28‐CRP response criteria as good or moderate responders. Over the treatment period a reduction of serum CRP predicted 90% of DAS28‐CRP responders and reduction of ESR predicted 97% of DAS28 responders, whereas a lack of CRP or ESR reductions predicted 54% and 45% non‐responders, respectively. Overall, the accuracy of changes in CRP and ESR in predicting treatment response according to DAS28‐CRP and DAS28 response criteria were 77% and 73%, respectively. CRP/DAS28‐CRP was more sensitive but less specific than ESR/DAS28 in predicting treatment response. Conclusion: Changes of CRP or ESR at the first stage of treatment can predict treatment response. Hence, measurement of serum CRP and ESR furnishes a reliable quantitative means for early anticipation of treatment response.     

Identification of clinical parameters associated with serum oxidative stress in patients with rheumatoid arthritis

Abstract

Objectives. Reactive oxygen species (ROS) are considered to be involved in the pathobiology of rheumatoid arthritis (RA); however, their association with disease activity has not been elucidated. In this study, we measured reactive oxygen metabolites (ROM) in patients with RA using a new Free Radical Analytical System and determined clinical parameters associated with ROM.

Methods. One hundred and fifty-two patients with RA and 80 patients with diabetes mellitus (DM) were included in this observational study. To measure ROM, the d-ROM test was performed on blood samples drawn from all subjects. The correlation between ROM and biomarkers, disease activity, doses of methotrexate (MTX), and prednisolone (PSL) were investigated.

Results. There were significant, positive correlations between ROM and CRP, matrix metalloproteinase 3 (MMP3), Disease Activity Score 28–erythrocyte sedimentation rate (DAS28-ESR), Clinical Disease Activity Index (CDAI), and the Simplified Disease Activity Index (SDAI). Multiple regression analysis revealed that CRP and DAS28-ESR were correlated with ROM.

Conclusions. The serum level of ROM was associated with CRP and DAS28-ESR, suggesting that ROM, in conjunction with CRP and MMP3, may be able to be used as a new biological disease marker to evaluate the disease activity of RA.     

Serum calprotectin may reflect inflammatory activity in patients with active rheumatoid arthritis despite normal to low C-reactive protein

Approximately half of patients with rheumatoid arthritis (RA) have normal C-reactive protein (CRP) levels. Calprotectin is a promising and likely more specific biomarker of disease activity than conventionally used acute phase reactants. We aimed to analyse the levels of serum calprotectin in RA patients with clinically active disease and with normal/low CRP. A total of 160 RA patients underwent clinical examination (DAS28-ESR and CDAI). The levels of calprotectin were analysed in patients with moderate to high disease activity with normal/low CRP levels and in 32 healthy subjects. The discriminatory capacity of calprotectin to identify clinically active patients in spite of normal/low CRP was assessed using ROC curves. Out of all RA patients, 74/160 (46.3%) were in remission or had low disease activity according to DAS28 and had normal/low CRP levels. However, 51/160 (32%) had normal/low CRP levels despite having moderate to high disease activity. In these patients, calprotectin levels were significantly higher than those in patients who had normal/low CRP and were in remission or showed low disease activity (2.7?±?1.5 vs. 2.1?±?1.2 μg/mL, p?=?0.043), which differed from those in healthy subjects (2.7?±?1.5 vs. 1.9?±?1.2 μg/mL, p?=?0.011). The discriminatory capacity for calprotectin to distinguish clinically active vs. inactive disease despite normal/low CRP using AUC of the DAS28 was 0.607 (95% CI 0.503 to 0.711, p?=?0.043). The present study demonstrates that calprotectin may reflect inflammatory activity in RA patients where CRP fails to do so.     

C-reactive protein-mediated complement activation in polymyalgia rheumatica and other systemic inflammatory diseases

Summary An immunoglobulin-independent deposition of the complement (C) components C4 and C3 occurs on rat kidney medullary structures, when sera of patients with various inflammatory diseases are studied by indirect immunofluorescence. The diagnostic value of this new test (C4-C3-IFT) for polymyalgia rheumatica (PMR) is stressed, since all sera from patients with active disease yielded positive reactions. Though highly sensitive with respect to PMR, C4/C3-IFT is not specific for this syndrome. Examples of positive reactions in systemic inflammatory diseases other than PMR are documented. Besides the clinical studies, C4/C3-IFT reactivity was analyzed with regard to the mechanisms of the reaction. Experimental data are presented which suggest that C-reactive protein (CRP) binds to rat kidney structures, thereby activating the classical C cascade. As a result of CRP-C interaction, C4 and C3 components are fixed to distinct renal medullary structures. Because of its technical simplicity, C4/C3-IFT can routinely be used to screen patients' sera for CRP-mediated C activation. This ex vivo test system may contribute to a better understanding of pathophysiological functions of serum CRP in various inflammatory diseases.This paper is dedicated to Prof. Dr. Dr. G. W. Löhr on the occasion of his 65th birthday