scholarly journals POS0395 ANTI-ACETYLATED PROTEIN ANTIBODIES IN RHEUMATOID ARTHRITIS (RA): CLUES FOR THE STARTING POINT OF AUTOANTIBODY RESPONSES IN RA

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 426.3-427
Author(s):  
T. J. van Wesemael ◽  
A. L. Dorjée ◽  
T. Huizinga ◽  
A. van der Helm - van Mil ◽  
R. Toes ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Healthy Controls ◽  
Serum Samples ◽  
Baseline Serum ◽  
Control Peptide ◽  
Autoantibody Response ◽  
Starting Point ◽  
Early Inflammatory Arthritis ◽  
And Control ◽  
Citrullinated Protein

Background:Rheumatoid arthritis (RA) is characterized by autoantibodies such as rheumatoid factor (RF) and anti-modified protein autoantibodies (AMPAs) like anti-citrullinated protein antibodies (ACPA) and anti-carbamylated protein antibodies (anti-CarP). Recently, another AMPA: anti-acetylated protein antibodies (AAPA) have been found in RA patients [1]. The prevalence of AAPA antibodies and their isotypes have yet to be determined. Since isotype profiles reflect the breadth of an immune response, the prevalence of AAPA isotypes in arthritis patients with and without RA can help to understand the relevance of this autoantibody response in RA.Objectives:To describe the prevalence of AAPA isotypes in arthritis patients with and without RA.Methods:In 650 RA patients fulfilling the 1987 RA criteria and 555 non-RA arthritis patients from the Leiden Early Arthritis Cohort, baseline serum samples were screened by ELISA for IgG, IgM and IgA to an acetylated- and control peptide that was based upon the CCP-2 backbone. The cutoff for positivity was based on 80 controls (mean + 2SD). A sample was considered positive if it was above the cutoff and was 0.1 optical density higher on the acetylated peptide than on the control peptide.Results:AAPA IgG was found in 36% of RA patients versus 6.7% of non-RA arthritis patients (figure 1a). Within RA patients, AAPA IgG antibodies were mostly present in the ACPA-(CCP-2) positive group (64% in ACPA-positive, compared to 5% in ACPA-negative). Levels of AAPA IgG and IgA were higher in RA patients than in healthy controls and non-RA arthritis patients (figure 1b), however, surprisingly, no difference in levels was found for IgM.When isotype profiles in AAPA- positive arthritis patients were compared, patients with RA were more often positive for two or more isotypes then patients without RA, and thus displayed considerably more overlap in AAPA isotypes compared to non-RA patients (table 1). Intriguingly, IgM AAPA was the most prevalent isotype in non-RA patients, versus IgG in RA patients.Table 1.Anti-acetylated protein antibody (AAPA) isotype overlap in AAPA positive patients.AAPA isotypeRA patients (=310) n (%)Non-RA arthritis patients (n=106) n (%)IgG+IgM-IgA-115 (37.1)28 (5.1)IgG-IgM+IgA-52 (16.8)48 (8.7)IgG-IgM-IgA+14 (4.5)13 (2.3)IgG+IgM+IgA-24 (7.7)3 (0.5)IgG+IgM-IgA+37 (11.9)4 (0.7)IgG-IgM+IgA+9 (2.9)8 (1.4)IgG+IgM+IgA+59 (19.0)2 (0.4)AAPA: anti-acetylated protein antibodies, RA: rheumatoid arthritisConclusion:AAPA are detected in one third of RA patients, and mainly in the ACPA-positive subgroup. The predominance of IgM AAPA in non-RA arthritis patients and healthy controls suggests that healthy persons can develop AAPA IgM without the development of RA. These results also suggest that in healthy individuals, AAPA responses can occur, but do not mature past the IgM-stage, while in RA patients, the AAPA-response does mature and might form a “starting point” for development of other AMPA leading to the concurrent present of several AMPA in disease.References:[1]Juarez, M., et al., Identification of novel antiacetylated vimentin antibodies in patients with early inflammatory arthritis. Ann Rheum Dis, 2016. 75(6): p. 1099-107.Disclosure of Interests:None declared

scholarly journals FRI0596 NOVEL AUTOANTIBODY BIOMARKERS FOR THE PREDICTION OF THERAPY RESPONSE IN RHEUMATOID ARTHRITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 904.1-904
Author(s):  
P. Vandormael ◽  
A. Pues ◽  
E. Sleurs ◽  
P. Verschueren ◽  
V. Somers
Keyword(s):  
Rheumatoid Arthritis ◽  
Therapy Response ◽  
Autoimmune Disorder ◽  
First Line ◽  
Research Support ◽  
Serum Samples ◽  
Glucocorticoid Treatment ◽  
Baseline Serum ◽  
Disease Remission ◽  
Antibody Reactivity

Background:Rheumatoid arthritis (RA) is an autoimmune disorder that is characterized by chronic inflammation of the joint synovium and presence of autoantibodies in most patients. For RA, many treatments are currently available but each treatment will only induce disease remission in a subset of patients. Moreover, finding out which patients respond well to first-line therapy with classical synthetic disease modifying anti-rheumatic drugs (csDMARDs), still largely depends on trial and error.Objectives:In this study, we aim to find novel RA autoantibody biomarkers that predict therapy response to csDMARDs before the initiation of treatment.Methods:In the CareRA trial, a Flemish multicenter study of different treatment regimes, serum samples were collected from RA patients that did or did not show disease remission (DAS28(CRP)<2.6) in response to csDMARDs, combined with a step down glucocorticoid treatment. In our study, baseline samples, collected before the start of treatment, were used to determine predictive antibody reactivity. A cDNA phage display library, representing the antigens from RA synovial tissue, was constructed and screened for antibody reactivity in baseline serum samples of RA patients that failed to reach remission at week 16. Using enzyme-linked immunosorbent assays (ELISA), antibody reactivity against the identified antigens was initially determined in pooled baseline serum samples of RA patients that did (n=50) or did not (n=40) reach disease remission at week 16. Antigenic targets that showed increased antibody reactivity in pools from patients that did not reach disease remission, were further validated in individual serum samples of 69 RA patients that did not reach DAS28(CRP) remission at week 16, and 122 RA patients that did.Results:Screening and validation of antibody reactivity resulted in 41 novel antigens. The retrieved antigenic sequences correspond to (parts of) known proteins and to randomly formed peptides. A panel of 3 of these peptide antigens could be composed, whose baseline antibody reactivity correlated with lack of therapy response at week 16. Presence of antibodies against at least one of these 3 antigens was significantly higher in individual samples of RA patients that did not reach DAS28(CRP) remission (43 vs. 29%, p=0.041), or that failed to reach ACR 70 (42 vs. 26%, p=0.029) response criteria at week 16, compared to RA patients that did reach these respective criteria. In addition, RA patients which were positive for this antibody panel at baseline, also showed less DAS(CRP) remission at week 4 and week 8.Conclusion:We have identified a set of 3 antibody biomarkers that can predict failure of early disease remission after first-line RA therapy, which might contribute to personalized medicine decisions.Disclosure of Interests:Patrick Vandormael: None declared, Astrid Pues: None declared, Ellen Sleurs: None declared, Patrick Verschueren Grant/research support from: Pfizer unrestricted chair of early RA research, Speakers bureau: various companies, Veerle Somers Grant/research support from: Research grant from Pfizer and BMS

scholarly journals THU0105 ISOTOPE-LABELING-LC-MS-BASED METABOLIC PROFILING OF MULTIPLE SERUM SAMPLE SETS FOR THE DISCOVERY OF HIGH-CONFIDENCE RHEUMATOID ARTHRITIS BIOMARKERS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 266.2-267
Author(s):  
W. Han ◽  
X. Wang ◽  
L. Li ◽  
S. Wichuk ◽  
E. Hutchings ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
High Performance ◽  
Isotope Labeling ◽  
Support Vector ◽  
Healthy Controls ◽  
High Confidence ◽  
Serum Samples ◽  
Worst Case ◽  
Advisory Boards ◽  
Pooled Sample

Background:Early diagnosis of rheumatoid arthritis (RA) is hampered by suboptimal accuracy of currently available serological biomarkers. Metabolomics may reveal promising biomarker candidates associated with the biomolecular processes of RA. In this work, we applied a high-performance chemical isotope labeling (CIL) LC-MS technique for in-depth profiling of the amine/phenol-submetabolome in serum samples. To avoid false positives and obtain high-confidence biomarker candidates, we analyzed three independent sets of serum samples collected from RA patients and healthy controls to examine the common effects.Objectives:We aimed to identify a metabolite signature with consistently high accuracy for RA.Methods:Serum samples were taken from 3 RA cohorts, which comprised 50, 49, and 131 RA patients, respectively. Within each cohort, there were sex/age-matched healthy controls: 50 in Cohort 1, 50 in Cohort 2, and 100 in Cohort 3. Among these 446 subjects, 75% were females and the average age was 52.5 years. Amine/phenol-containing metabolites were labeled by12C-dansyl chloride to improve the LC-MS detection. For each cohort, a pooled sample was prepared and labeled by13C-dansyl group to serve as the reference sample for relative quantification. Then the individual samples and the pooled sample were mixed 1:1. Finally, an LC-QTOF-MS platform analyzed the mixtures and output the intensity ratios of12C/13C peak pairs.Results:1,149 amine/phenol-containing metabolites were commonly detected across the three sample sets. Among them, 134 were positively identified by our dansyl-labeling standard library, and 141 were matched to predicted retention times and mass values of dansyl-labeled human metabolites. Visualized by the partial least squares discriminant analysis (PLS-DA), the overall amine/phenol-submetabolome demonstrated clear and consistent differences between healthy controls and the RA groups, with cross-validation Q2 = 0.765, 0.745, 0.793, respectively. The selection of significant metabolites was conducted according to the fold change and false-discovery-rate-adjusted Welch’s t-test. Cohort 1 demonstrated 85 metabolites having higher concentrations in the RA samples than the controls, and 89 metabolites with lowered concentrations. The numbers of increased/decreased metabolites in Cohort 2 and 3 were 87/26 and 90/53, respectively. Importantly, there were 59 significantly discriminatory metabolites commonly found in the three data sets (49 increased and 9 decreased). We picked the top three with the highest univariate classification performance to form a biomarker panel. We implemented the linear support vector machine (SVM) to build the classifier and the receiver operating characteristic (ROC) analysis to measure the performance. The area-under-the-curve (AUC) values (95% confidence interval) were 1.000 (1.000-1.000), 0.992 (0.967-1.000) and 0.902 (0.858-0.945) for the three cohorts, respectively. The results revealed the importance of examining multiple sample sets and even in the worst case (Cohort 3), our biomarker candidates could differentiate RA at 82.5% sensitivity and 82.5% specificity. Particularly, in Cohort 3, there were 30 RA patients negative for anti-cyclic citrullinated peptide and rheumatoid factor, and our metabolite panel demonstrated consistently high performance for differentiating these specific subjects from healthy controls.Conclusion:Metabolites showing significant and consistent changes associated with RA have been identified with high discriminative power.Disclosure of Interests:Wei Han: None declared, Xiaohang Wang: None declared, Liang Li: None declared, Stephanie Wichuk: None declared, Edna Hutchings: None declared, Rana Dadashova: None declared, Joel Paschke: None declared, Walter P Maksymowych Grant/research support from: Received research and/or educational grants from Abbvie, Novartis, Pfizer, UCB, Consultant of: WPM is Chief Medical Officer of CARE Arthritis Limited, has received consultant/participated in advisory boards for Abbvie, Boehringer, Celgene, Eli-Lilly, Galapagos, Gilead, Janssen, Novartis, Pfizer, UCB, Speakers bureau: Received speaker fees from Abbvie, Janssen, Novartis, Pfizer, UCB.

scholarly journals BAFF Predicts Immunogenicity in Older Patients With Rheumatoid Arthritis Treated With TNF Inhibitors

2020 ◽  
Author(s):  
Borja Hernández-Breijo ◽  
Victoria Navarro-Compán ◽  
Chamaida Plasencia-Rodríguez ◽  
Ioannis Parodis ◽  
Johanna E. Gehin ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Older Patients ◽  
Operating Characteristic ◽  
Certolizumab Pegol ◽  
Positive Likelihood Ratio ◽  
Characteristic Analysis ◽  
Serum Samples ◽  
Chi Square ◽  
Baseline Serum ◽  
Logistic Regression Models

Abstract Background: Immunogenicity related to treatment with TNF inhibitors (TNFi) is one of the causes for the decreased attainment of clinical response in patients with rheumatoid arthritis (RA). The B-cell activating factor (BAFF) may be playing a role in the development of immunogenicity. The objective of this study was to analyse the association of baseline concentration of serum BAFF with immunogenicity after 6 months of TNFi treatment.Methods: A total of 139 patients with RA starting a TNFi (infliximab, adalimumab, certolizumab pegol or golimumab) were followed-up for 6 months. Serum samples were obtained at baseline and at 6 months and anti-drug antibody (ADA) and BAFF concentrations were measured. Logistic regression models were employed in order to analyse the association between BAFF concentrations and immunogenicity. Receiver operating characteristic analysis was performed to determine the BAFF concentrations with a greater likelihood of showing immunogenicity association.Results: At 6 months, 39 patients (28%) developed ADA. A significant interaction between the age and baseline BAFF concentration was found for the development of ADA (Wald chi-square value=5.30; p=0.02); therefore, subsequent results were stratified according to mean age (≤/>55 years). Baseline serum BAFF concentration was independently associated with ADA development only in patients over 55 years (OR=1.55; 95% CI: 1.03-2.12). Baseline serum BAFF≥1034pg/mL predicted the presence of ADA at 6 months (positive likelihood ratio=3.7).Conclusions: Our results suggest that the association of BAFF concentration and immunogenicity depends on the patient’s age. Baseline serum BAFF concentration predicts the presence of ADA within 6 months of TNFi therapy in older patients with RA.

scholarly journals Differential Expression of Serum Exosomal miRNAs in Breast Cancer Patients and Healthy Controls

2021 ◽  
Author(s):  
Rahim Asgari ◽  
Jafar Rezaie
Keyword(s):  
Breast Cancer ◽  
Cancer Patients ◽  
Circulatory System ◽  
Health Concern ◽  
Healthy Controls ◽  
Flow Cytometry Analysis ◽  
Breast Cancer Patients ◽  
Serum Samples ◽  
Exosomal Mirnas ◽  
And Control

Purpose: Breast cancer has become as a serious public health concern worldwide. Breast cancer cells release exosomes into the circulatory system, which are easily accessible for further analysis like cancer diagnosis. In this study, we aimed to investigate expression of circulating exosomal miRNAs (miRs) in the serum of individuals with breast cancer and healthy controls. Methods: Exosomes were collected from serum samples using a commercial kit and characterized by scanning electron microscopy (SEM) and flow cytometry analysis. Expression of miRs such as miR-21, miR-155, miR-182, miR-373, and miR-126 were evaluated by real-time PCR. Results: The result showed that the expression level of exosomal miR-21, miR-155, miR-182, and miR-373 in the serum of breast cancer patients was higher than of those controls (P<0.05). However, expression of miR-126 did not change between breast cancer and control individuals (P>0.05). Conclusion: Our results showed a different miRs expression pattern between breast cancer and healthy samples, supposing potential biomarkers for breast cancer. Further studies focusing on these miRs are required to confirm our findings.

Antimodified protein antibody response pattern influences the risk for disease relapse in patients with rheumatoid arthritis tapering disease modifying antirheumatic drugs

2016 ◽  
Vol 76 (2) ◽  
pp. 399-407 ◽  
Author(s):  
Camille P Figueiredo ◽  
Holger Bang ◽  
Jayme Fogagnolo Cobra ◽  
Matthias Englbrecht ◽  
Axel J Hueber ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Antibody Response ◽  
Multivariate Logistic Regression Analysis ◽  
Sustained Remission ◽  
Disease Relapse ◽  
Serum Samples ◽  
Baseline Serum ◽  
Dmard Therapy ◽  
Relapse Risk ◽  
Disease Modifying

ObjectiveTo perform a detailed analysis of the autoantibody response against post-translationally modified proteins in patients with rheumatoid arthritis (RA) in sustained remission and to explore whether its composition influences the risk for disease relapse when tapering disease modifying antirheumatic drug (DMARD) therapy.MethodsImmune responses against 10 citrullinated, homocitrullinated/carbamylated and acetylated peptides, as well as unmodified vimentin (control) and cyclic citrullinated peptide 2 (CCP2) were tested in baseline serum samples from 94 patients of the RETRO study. Patients were classified according to the number of autoantibody reactivities (0–1/10, 2–5/10 and >5/10) or specificity groups (citrullination, carbamylation and acetylation; 0–3) and tested for their risk to develop relapses after DMARD tapering. Demographic and disease-specific parameters were included in multivariate logistic regression analysis for defining the role of autoantibodies in predicting relapse.ResultsPatients varied in their antimodified protein antibody response with the extremes from recognition of no (0/10) to all antigens (10/10). Antibodies against citrullinated vimentin (51%), acetylated ornithine (46%) and acetylated lysine (37%) were the most frequently observed subspecificities. Relapse risk significantly (p=0.011) increased from 18% (0–1/10 reactivities) to 34% (2–5/10) and 55% (>5/10). With respect to specificity groups (0–3), relapse risk significantly (p=0.021) increased from 18% (no reactivity) to 28%, 36% and finally to 52% with one, two or three antibody specificity groups, respectively.ConclusionsThe data suggest that the pattern of antimodified protein antibody response determines the risk of disease relapse in patients with RA tapering DMARD therapy.Trial registration number2009-015740-42; Results.

scholarly journals Increased Concentrations of Antibody-Bound Circulatory Cell-Free DNA in Rheumatoid Arthritis

2007 ◽  
Vol 53 (9) ◽  
pp. 1609-1614 ◽  
Author(s):  
Xiao-Yan Zhong ◽  
Ines von Mühlenen ◽  
Ying Li ◽  
Anjeung Kang ◽  
Anurag Kumar Gupta ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Animal Experiments ◽  
Basic Research ◽  
Healthy Controls ◽  
Serum Samples ◽  
Cell Free Dna ◽  
Free Dna ◽  
New Evidence

Abstract Background: Increased concentrations of cell-free DNA have been found in several disorders and have been interpreted as evidence of increased rates of cell death or turnover. Evidence from in vitro and animal experiments suggests that DNA may play a role in the pathogenesis of rheumatoid arthritis (RA). Methods: We measured cell-free DNA in plasma and serum from patients with RA and healthy controls by use of quantitative PCR for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) DNA. We used protein G Sepharose™ bead adsorption of plasma and elution to isolate antibody-bound DNA. Results: In paired plasma and serum samples of 16 healthy controls the median GAPDH copies were 4500 genome equivalents (GE)/mL plasma (range 319–21 000) and in 26 RA patients 17 000 GE/mL plasma (2100–2 375 000, P = 0.0001). In the serum from normal controls the median GAPDH copies were 35 000 GE/mL (1700–239 000) and from RA patients 222 000 GE/mL (21 000–2 375 000, P = 0.004). A median of 81% of the cell-free DNA in RA was associated with antibody compared with 9% in healthy controls (P = 0.001). The concentrations of DNA did not vary with the type of therapy patients received. Conclusions: These results provide new evidence for a role of cell-free DNA-antibody complexes in the etiology of RA, suggest new avenues for basic research, and may prove to be relevant to diagnosis and assessment of therapy.

scholarly journals Association Between STAT4 rs7574865 Polymorphism and Rheumatoid Arthritis: Debate Unresolved

2018 ◽  
Vol 12 (1) ◽  
pp. 172-178
Author(s):  
Iman Tarakji ◽  
Wafa Habbal ◽  
Fawza Monem
Keyword(s):  
Rheumatoid Arthritis ◽  
Genetic Factors ◽  
Shared Epitope ◽  
Direct Sequencing ◽  
Healthy Controls ◽  
Asian Populations ◽  
Genotype Frequencies ◽  
Potential Impact ◽  
Acpa Status ◽  
Citrullinated Protein

Background: STAT4 rs7574865 polymorphism has been evidently associated with susceptibility to Rheumatoid Arthritis (RA) in European and Eastern Asian populations, whereas studies in other countries reported otherwise. Objective: We investigated the distribution of STAT4 rs7574865 polymorphism in a group of Syrian RA patients. Methods: Eighty-one RA patients and forty healthy controls were enrolled and STAT4 rs7574865 was genotyped by direct sequencing. RA patients were stratified according to Anti-Citrullinated Protein Antibodies (ACPA) status for analysis. Results: Minor T allele frequencies were 30.4%, 16.7%, and 23.8% in ACPA-positive RA patients, ACPA-negative RA patients, and healthy controls, respectively. No significant differences in STAT4 rs7574865 allele/genotype frequencies were found between ACPA-positive RA patients, ACPA-negative RA patients, and healthy controls (P>0.05). Conclusion: STAT4 rs7574865 TT genotype showed a potential impact on ACPA positivity in Syrian RA patients. However, STAT4 rs7574865 effect on RA onset and severity is minor compared to other genetic factors such as HLA-DRB1 shared epitope alleles.

Circulating Dickkopf-1 Is Correlated with Bone Erosion and Inflammation in Rheumatoid Arthritis

2011 ◽  
Vol 38 (5) ◽  
pp. 821-827 ◽  
Author(s):  
SHI-YAO WANG ◽  
YAN-YING LIU ◽  
HUA YE ◽  
JIAN-PING GUO ◽  
RU LI ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Rheumatic Diseases ◽  
Bone Erosion ◽  
Interleukin 1 ◽  
Healthy Controls ◽  
Serum Samples ◽  
Reactive Protein ◽  
Tnf Α ◽  
Factor Α ◽  
Dickkopf 1

Objective.To explore the potential role of Dickkopf-1 (DKK-1) in rheumatoid arthritis (RA) and to evaluate the effect of a tumor necrosis factor-α (TNF-α) inhibitor (infliximab) and an interleukin 1 receptor antagonist (IL-1Ra; anakinra) on DKK-1 secretion in patients with RA.Methods.Serum samples were collected from 100 patients with RA, 100 patients with other rheumatic diseases (e.g., osteoarthritis and ankylosing spondylitis), and 40 healthy controls. DKK-1 and osteoprotegerin (OPG) levels in serum were detected by ELISA. Serum C-reactive protein (CRP) levels, erythrocyte sedimentation rates (ESR), rheumatoid factor (RF) titers, and anti-cyclic citrullinated peptide antibody were also measured in patients with RA.Results.The serum level of DKK-1 was significantly higher in patients with RA than in healthy controls and those with other rheumatic diseases (p < 0.01); the serum DKK-1 level was correlated with levels of CRP (r = 0.488, p = 0.003) and ESR (r = 0.458, p = 2.4 x 10−4) and the Sharp score of radiologic change (r = 0.449, p = 0.001) in RA. In contrast to the increasing level of OPG, DKK-1 was significantly decreased in RA patients treated with TNF-α inhibitor (p < 0.01). DKK-1 was significantly decreased in RA patients treated with IL-1Ra (p < 0.01).Conclusion.DKK-1, as an important mediator, was correlated with bone erosion and inflammation in RA. The change of DKK-1 level may serve as a biomarker of disease activity and bone erosion.

scholarly journals Technical and Diagnostic Performance of 6 Assays for the Measurement of Citrullinated Protein/Peptide Antibodies in the Diagnosis of Rheumatoid Arthritis

2007 ◽  
Vol 53 (3) ◽  
pp. 498-504 ◽  
Author(s):  
Dries Coenen ◽  
Patrick Verschueren ◽  
René Westhovens ◽  
Xavier Bossuyt
Keyword(s):  
Rheumatoid Arthritis ◽  
Diagnostic Accuracy ◽  
Diagnostic Performance ◽  
Connective Tissue Diseases ◽  
Antigen Specificity ◽  
Serum Samples ◽  
Technical Performance ◽  
Two Samples ◽  
Citrullinated Protein ◽  
Peptide Antibodies

Abstract Background: Several anticitrullinated protein/peptide antibodies (ACPA) assays have been reported to be of diagnostic value for rheumatoid arthritis (RA). We evaluated the technical performance and diagnostic accuracy of 6 ELISAs for the detection of antibodies to citrullinated protein/peptide antigens. Methods: ACPA were determined in 298 serum samples using 6 commercially available ACPA assays. One hundred two samples were from RA patients, including patients with early and established RA, and 196 were from controls, including patients with psoriatic arthritis, connective tissue diseases, organ-specific autoimmune diseases, and a group of consecutive patients for whom a rheumatologist ordered anticyclic citrullinated peptide (CCP) antibodies. The ELISA reagent sets under study were Citrullinated Protein Antibodies (Genesis), Anti-MCV (Orgentec), Immunoscan RA (Euro-Diagnostica), Anti-CCP IgG ELISA (Euroimmun), EliA™ CCP (Phadia), and Quanta Lite™ CCP3 IgG ELISA (Inova). Technical performance (imprecision, linearity, correlation, and agreement) and diagnostic accuracy (sensitivity and specificity) were compared. Results: Variable technical performance was noted among the different ACPA assays, with some assays displaying poor reproducibility and bad linearity. ACPA results were well correlated among assays with the same antigen specificity, but the numerical values reported for each assay differed widely. Using cutoff values proposed by the manufacturer, diagnostic sensitivities ranged between 69.6% and 77.5% and specificities between 87.8% and 96.4%. The areas under the ROC curves were comparable among the different assays. Conclusions: Overall diagnostic performance of ACPA assays is comparable among the different assays, but standardization is needed. For some assays, analytical characteristics could be improved.

Multiple antibody reactivities to citrullinated antigens in sera from patients with rheumatoid arthritis: association with HLA-DRB1 alleles

2008 ◽  
Vol 68 (5) ◽  
pp. 736-743 ◽  
Author(s):  
O Snir ◽  
M Widhe ◽  
C von Spee ◽  
J Lindberg ◽  
L Padyukov ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Shared Epitope ◽  
Type Ii Collagen ◽  
Cross Reactivity ◽  
Igg Antibodies ◽  
Serum Samples ◽  
Hla Dr ◽  
Citrullinated Proteins ◽  
The Relationship ◽  
Citrullinated Protein

Background:Autoantibodies to cyclic citrullinated peptides (anti-CCP) are present in most patients with rheumatoid arthritis (RA), and associate with HLA-DRB1 shared epitope (SE) alleles.Objective:To investigate reactivities of anti-CCP to various citrullinated proteins/peptides, which represent potential autoantigens in RA, and to examine the relationship between such antibodies, and their association with genetic variants within HLA-DRB1 SE alleles.Methods:Serum samples from 291 patients with established RA and 100 sex- and age-matched healthy subjects were included in this study. Sera were first analysed for presence of anti-CCP antibodies and further for IgG and IgA antibodies towards candidate autoantigens in both their native and citrullinated form including: fibrinogen, α-enolase peptide-1 and the C1-epitope of type II collagen (C1III). Antibody specificity was confirmed by cross-reactivity tests. HLA-DR genotyping was performed.Results:72% of patients with RA were anti-CCP positive. Among the candidate autoantigens examined, IgG antibodies to citrullinated fibrinogen were found in 66% of patients’ sera and in 41% for both citrullinated α-enolase peptide-1 and citrullinated C1III. These antibodies were mainly seen in the anti-CCP-positive patient group; they were specific for their respective antigen and displayed limited cross reactivity. IgA responses were also detected, but less frequently than IgG. Anti-CCP and anti-citrullinated protein antibodies were associated with HLA-DRB1*04 rather than with HLA-DRB1*01 alleles.Conclusions:Antibodies directed against several citrullinated antigens are present in CCP-positive RA, with many patients displaying multireactivity. All specific reactivities were primarily associated with the HLA-DRB1*04 alleles, suggesting common pathways of anti-citrulline immunity.

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