Diagnostic value of anti-cyclic citrullinated peptide antibodies in Greek patients with rheumatoid arthritis

Background: Anti-cyclic citrullinated peptide (anti-CCP) antibodies have been of diagnostic value in Northern European Caucasian patients with rheumatoid arthritis ( RA). In these populations, anti-CCP antibodies are associated with the HLA-DRB1 shared epitope. We assessed the diagnostic value of anti-CCP antibodies in Greek patients with RA where the HLA shared epitope was reported in a minority of patients. Methods: Using an enzyme-linked immunosorbent assay ( ELISA) (CCP2) kit, we tested anti-CCP antibodies in serum samples from 155 Greek patients with RA, 178 patients with other rheumatic diseases, and 100 blood donors. We also determined rheumatoid factor (RF) and compared it to anti-CCP antibodies for area under the curve (AUC), sensitivity, specificity and likelihood ratios. Results: Sensitivity of anti-CCP2 antibodies and RF for RA was 63.2% and 59.1%, and specificity was 95.0% and 91.2%, respectively. When considered simultaneously, the AUC for anti-CCP antibodies was 0.90 with 95% CI of 0.87 to 0.93 and the AUC for RF was 0.71 with 95% CI of 0.64 to 0.77. The presence of both antibodies increased specificity to 98.2%. Anti-CCP antibodies were positive in 34.9% of RF-negative RA patients. Anti-CCP antibodies showed a correlation with the radiographic joint damage. Anti-CCP-positive RA patients had increased the swollen joint count and serum CRP concentration compared to anti-CCP-negative RA patients (Mann-Whitney U test, p = 0.01, and p < 0.001, respectively). However, no correlation was found between anti-CCP antibodies and DAS28 score ( r = 0.13, p = 0.12). Conclusion: In Greek patients with RA, anti-CCP2 antibodies exhibit a better diagnostic value than RF and a correlation with radiological joint damage and therefore are useful in everyday rheumatology practice

Anticitrullinated protein antibody (ACPA) in rheumatoid arthritis: influence of an interaction between HLA-DRB1 shared epitope and a deletion polymorphism in glutathione s-transferase in a cross-sectional study

Abstract Introduction A deletion polymorphism in glutathione S-transferase Mu-1 (GSTM1-null) has previously been implicated to play a role in rheumatoid arthritis (RA) risk and progression, although no prior investigations have examined its associations with anticitrullinated protein antibody (ACPA) positivity. The purpose of this study was to examine the associations of GSTM1-null with ACPA positivity in RA and to assess for evidence of interaction between GSTM1 and HLA-DRB1 shared epitope (SE). Methods Associations of GSTM1-null with ACPA positivity were examined separately in two RA cohorts, the Veterans Affairs Rheumatoid Arthritis (VARA) registry (n = 703) and the Study of New-Onset RA (SONORA; n = 610). Interactions were examined by calculating an attributable proportion (AP) due to interaction. Results A majority of patients in the VARA registry (76%) and SONORA (69%) were positive for ACPA with a similar frequency of GSTM1-null (53% and 52%, respectively) and HLA-DRB1 SE positivity (76% and 71%, respectively). The parameter of patients who had ever smoked was more common in the VARA registry (80%) than in SONORA (65%). GSTM1-null was significantly associated with ACPA positivity in the VARA registry (odds ratio (OR), 1.45; 95% confidence interval (CI), 1.02 to 2.05), but not in SONORA (OR, 1.00; 95% CI, 0.71 to 1.42). There were significant additive interactions between GSTM1 and HLA-DRB1 SE in the VARA registry (AP, 0.49; 95% CI, 0.21 to 0.77; P &lt; 0.001) in ACPA positivity, an interaction replicated in SONORA (AP, 0.38; 95% CI, 0.00 to 0.76; P = 0.050). Conclusions This study is the first to show that the GSTM1-null genotype, a common genetic variant, exerts significant additive interaction with HLA-DRB1 SE on the risk of ACPA positivity in RA. Since GSTM1 has known antioxidant functions, these data suggest that oxidative stress may be important in the development of RA-specific autoimmunity in genetically susceptible individuals

Multiomics analysis of rheumatoid arthritis yields sequence variants that have large effects on risk of the seropositive subset

Funding Information: Funding The study was funded by NORDFORSK (grant agreement no. 90825, project NORA), the Swedish Research Council (2018-02803), the Swedish innovation Agency (Vinnova), Innovationsfonden and The Research Council of Norway, Region Stockholm-Karolinska Institutet and Region Västerbotten (ALF), the Danish Rheumatism Association (R194-A6956), the Swedish Brain Foundation, Nils and Bibbi Jensens Foundation, the Knut and Alice Wallenberg Foundation, Margaretha af Ugglas Foundation, the South-Eastern Heath Region of Norway, the Health Research Fund of Central Denmark Region, Region of Southern Denmark, the A.P. Moller Foundation for the Advancement of Medical Science, the Colitis-Crohn Foreningen, the Novo Nordisk Foundation (NNF15OC0016932), Aase og Ejnar Danielsens Fond, Beckett-Fonden, Augustinus Fonden, Knud and Edith Eriksens Mindefond, Laege Sofus Carl Emil Friis and Hustru Olga Doris Friis’ Legat, the Psoriasis Forskningsfonden, the University of Aarhus, the Danish Rheumatism Association (R194-A6956, A1923, A3037 and A3570 – www. gigtforeningen.dk), Region of Southern Denmark’s PhD Fund, 12/7725 (www.regionsyddanmark.dk) and the Department of Rheumatology, Frederiksberg Hospital (www.frederiksberghospital. dk). MoBa Genetics has been funded by the Research Council of Norway (#229624, #223273), South East and Western Norway Health Authorities, ERC AdG project SELECTionPREDISPOSED, Stiftelsen Kristian Gerhard Jebsen, Trond Mohn Foundation, the Novo Nordisk Foundation and the University of Bergen. KB and SB acknowledge the Novo Nordisk Foundation (grant NNF14CC0001). Funding Information: competing financial interests as employees. OAA is a consultant to HealthLytix. The following coauthors report the following but unrelated to the current report: Karolinska Institutet, with JA as principal investigator, has entered into agreements with the following entities, mainly but not exclusively for safety monitoring of rheumatology immunomodulators: Abbvie, BMS, Eli Lilly, Janssen, MSD, Pfizer, Roche, Samsung Bioepis and Sanofi, unrelated to the present study. SB has ownerships in Intomics A/S, Hoba Therapeutics Aps, Novo Nordisk A/S, Lundbeck A/S and managing board memberships in Proscion A/S and Intomics A/S. BG has received research grants from AbbVie, Bristol Myers-Squibb and Pfizer; OH has received research grants from AbbVie, Novartis and Pfizer, DVJ has received speaker and consultation fees from AbbVie, Janssen, Lilly, MSD, Novartis, Pfizer, Roche and UCB, AGL has received speaking and/or consulting fees from AbbVie, Janssen, Lilly, MSD, Novartis, Pfizer, Roche and UCB; and CT has received consulting fees from Roche, speaker fees from Abbvie, Bristol Myers-Squibb, Nordic Drugs, Pfizer and Roche, and an unrestricted grant from Bristol Myers-Squibb. Publisher Copyright: © Funding Information: Funding The study was funded by NORDFORSK (grant agreement no. 90825, project NORA), the Swedish Research Council (2018-02803), the Swedish innovation Agency (Vinnova), Innovationsfonden and The Research Council of Norway, Region Stockholm-Karolinska Institutet and Region Västerbotten (ALF), the Danish Rheumatism Association (R194-A6956), the Swedish Brain Foundation, Nils and Bibbi Jensens Foundation, the Knut and Alice Wallenberg Foundation, Margaretha af Ugglas Foundation, the South-Eastern Heath Region of Norway, the Health Research Fund of Central Denmark Region, Region of Southern Denmark, the A.P. Moller Foundation for the Advancement of Medical Science, the Colitis-Crohn Foreningen, the Novo Nordisk Foundation (NNF15OC0016932), Aase og Ejnar Danielsens Fond, Beckett-Fonden, Augustinus Fonden, Knud and Edith Eriksens Mindefond, Laege Sofus Carl Emil Friis and Hustru Olga Doris Friis’ Legat, the Psoriasis Forskningsfonden, the University of Aarhus, the Danish Rheumatism Association (R194-A6956, A1923, A3037 and A3570 – www. gigtforeningen.dk), Region of Southern Denmark’s PhD Fund, 12/7725 (www.regionsyddanmark.dk) and the Department of Rheumatology, Frederiksberg Hospital (www.frederiksberghospital. dk). MoBa Genetics has been funded by the Research Council of Norway (#229624, #223273), South East and Western Norway Health Authorities, ERC AdG project SELECTionPREDISPOSED, Stiftelsen Kristian Gerhard Jebsen, Trond Mohn Foundation, the Novo Nordisk Foundation and the University of Bergen. KB and SB acknowledge the Novo Nordisk Foundation (grant NNF14CC0001). Funding Information: competing financial interests as employees. OAA is a consultant to HealthLytix. The following coauthors report the following but unrelated to the current report: Karolinska Institutet, with JA as principal investigator, has entered into agreements with the following entities, mainly but not exclusively for safety monitoring of rheumatology immunomodulators: Abbvie, BMS, Eli Lilly, Janssen, MSD, Pfizer, Roche, Samsung Bioepis and Sanofi, unrelated to the present study. SB has ownerships in Intomics A/S, Hoba Therapeutics Aps, Novo Nordisk A/S, Lundbeck A/S and managing board memberships in Proscion A/S and Intomics A/S. BG has received research grants from AbbVie, Bristol Myers-Squibb and Pfizer; OH has received research grants from AbbVie, Novartis and Pfizer, DVJ has received speaker and consultation fees from AbbVie, Janssen, Lilly, MSD, Novartis, Pfizer, Roche and UCB, AGL has received speaking and/or consulting fees from AbbVie, Janssen, Lilly, MSD, Novartis, Pfizer, Roche and UCB; and CT has received consulting fees from Roche, speaker fees from Abbvie, Bristol Myers-Squibb, Nordic Drugs, Pfizer and Roche, and an unrestricted grant from Bristol Myers-Squibb. Publisher Copyright: ©Objectives To find causal genes for rheumatoid arthritis (RA) and its seropositive (RF and/or ACPA positive) and seronegative subsets. Methods We performed a genome-wide association study (GWAS) of 31 313 RA cases (68% seropositive) and ∼1 million controls from Northwestern Europe. We searched for causal genes outside the HLA-locus through effect on coding, mRNA expression in several tissues and/or levels of plasma proteins (SomaScan) and did network analysis (Qiagen). Results We found 25 sequence variants for RA overall, 33 for seropositive and 2 for seronegative RA, altogether 37 sequence variants at 34 non-HLA loci, of which 15 are novel. Genomic, transcriptomic and proteomic analysis of these yielded 25 causal genes in seropositive RA and additional two overall. Most encode proteins in the network of interferon-Alpha/beta and IL-12/23 that signal through the JAK/STAT-pathway. Highlighting those with largest effect on seropositive RA, a rare missense variant in STAT4 (rs140675301-A) that is independent of reported non-coding STAT4-variants, increases the risk of seropositive RA 2.27-fold (p=2.1×10-9), more than the rs2476601-A missense variant in PTPN22 (OR=1.59, p=1.3×10-160). STAT4 rs140675301-A replaces hydrophilic glutamic acid with hydrophobic valine (Glu128Val) in a conserved, surface-exposed loop. A stop-mutation (rs76428106-C) in FLT3 increases seropositive RA risk (OR=1.35, p=6.6×10-11). Independent missense variants in TYK2 (rs34536443-C, rs12720356-C, rs35018800-A, latter two novel) associate with decreased risk of seropositive RA (ORs=0.63-0.87, p=10-9-10-27) and decreased plasma levels of interferon-Alpha/beta receptor 1 that signals through TYK2/JAK1/STAT4. Conclusion Sequence variants pointing to causal genes in the JAK/STAT pathway have largest effect on seropositive RA, while associations with seronegative RA remain scarce.Peer reviewe