J Rheum Dis Journal of Rheumatic Diseases J Rheum Dis 2093-940X 2233-4718 Korean College of Rheumatology 10.4078/jrd.2024.0130 jrd-32-3-182 Original Article Change of autoantibody levels in established rheumatoid arthritis patients treated by biological disease-modifying anti-rheumatic drugs -the AIRTIGHT study- https://orcid.org/0000-0002-7439-0721 AnnoShohei M.D. 1 https://orcid.org/0000-0002-8747-7279 InuiKentaro M.D., Ph.D. 2 3 https://orcid.org/0000-0003-3161-3929 TadaMasahiro M.D., Ph.D. 4 https://orcid.org/0009-0007-7497-8967 SugiokaYuko M.D., Ph.D. 5 https://orcid.org/0000-0002-8849-9824 OkanoTadashi M.D., Ph.D. 5 https://orcid.org/0000-0002-7541-3745 MamotoKenji M.D., Ph.D. 2 https://orcid.org/0000-0002-1522-8740 KoikeTatsuya M.D., Ph.D. 6 Departments of Orthopaedic Surgery, Yodogawa Christian Hospital, Osaka, Japan Departments of Orthopaedic Surgery, Osaka Metropolitan University Medical School, Osaka, Japan Departments of Orthopaedic Surgery, Saiseikai Nakatsu Hospital, Osaka, Japan Departments of Orthopaedic Surgery, Osaka City General Hospital, Osaka, Japan Center for Senile Degenerative Disorders (CSDD), Osaka Metropolitan University Medical School, Osaka, Japan Search Institute for Bone and Arthritis Disease (SINBAD), Shirahama Foundation for Health and Welfare, Wakayama, Japan Corresponding author: Tatsuya Koike, https://orcid.org/0000-0002-1522-8740 Search Institute for Bone and Arthritis Disease (SINBAD), Shirahama Foundation for Health and Welfare, Nishimuro-gun Shirahama-cho 1447, Wakayama 649-2211, Japan. E-mail: tatsuya@omu.ac.jp 1 7 2025 3 2 2025 32 3 182 189 6 11 2024 17 12 2024 12 1 2025 Copyright © 2025 by The Korean College of Rheumatology. All rights reserved. 2025 This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective

Previous studies reported that abatacept (ABT) decreased autoantibodies in early rheumatoid arthritis (RA) patients. We investigated the impact of ABT, and other biological disease-modifying anti-rheumatic drugs (bDMARDs) on autoantibody levels in established RA patients.

 Methods

This prospective observational study included 50 RA patients treated with ABT and 115 RA patients treated with non-ABT bDMARDs. Serum levels of anticitrullinated peptide antibodies (ACPA), immunoglobulin (Ig) M-rheumatoid factor (IgM-RF), IgG-RF, and anti-agalactosyl IgG antibody (anti-Gal (0) IgG) were measured at baseline and after 48 weeks of treatment.

 Results

After propensity score matching, 25 patients with ABT and 25 patients with non-ABT were finally analyzed. Disease activity score in 28 joints using C-reactive protein significantly decreased in both ABT group (4.5 to 3.3, p<0.01) and non-ABT group (4.4 to 2.5, p<0.01) after 48 weeks treatment. In ABT group, median titers at baseline and 48 weeks were 62.7 and 57.8 U/mL for ACPA (p=0.22), 35.0 and 39.0 IU/mL for IgM-RF (p=0.21), 0.5 and 0.5 IU/mL for IgG-RF (p=0.19), and 50.4 and 53.5 AU/mL for anti-Gal (0) IgG (p=0.22), respectively. Changes of all autoantibody titer were not significant in ABT group. Non-ABT group showed significant decreases in ACPA (baseline 143.0 to 57.8 U/mL at week 48, p=0.03), IgM-RF (50.0 to 37.0 IU/mL, p<0.01), and anti-Gal (0) IgG (93.2 to 61.8 AU/mL, p<0.01) except IgG-RF (0.6 to 0.5 IU/mL, p=0.22).

 Conclusion

Autoantibody-lowering effect of ABT was not strong in established RA patients in our study.

 Rheumatoid arthritis Biological products Abatacept Serologic test INTRODUCTION

Rheumatoid arthritis (RA) is related to autoantibodies and several autoantibodies are used for diagnosis or evaluation of disease activity of RA [1]. Rheumatoid factor (RF) is positive in 70% of patients with RA, and RF is concerned with immune complexes that affect the disease pathogenesis [2]. Anti-citrullinated peptide antibodies (ACPA) are highly specific for RA [3]. The serum titer of anti-agalactosyl immunoglobulin (Ig) G antibody (anti-Gal (0) IgG) is also useful biomarker for RA diagnosis [4]. Abatacept (ABT) is a fusion protein that prevent the CD80/CD86 antigen on the antigen-presenting cell and CD28 antigen on the T-cell [5]. Human leukocyte antigen (HLA) strongly influence T-cell recognition [6]. The shared epitope containing HLA-DRB1 alleles contribute to the development of ACPA [7]. Previous study reported that one year treatment of ABT decreased serum levels of ACPA and RF in patients with early RA [8]. Japanese study reported that significantly larger decreases in ACPA and RF titer were observed in ABT compared to anti-tumor necrosis factor (anti-TNF) therapy at 3 months [9]. However, other studies showed that autoantibody titers decreased after 24 weeks treatment with biological disease-modifying anti-rheumatic drugs (bDMARDs) other than ABT such as interleukin-6 (IL-6) receptor inhibitor [10]. Anti-TNF inhibitor also reduced autoantibody titers after 46 weeks treatment [11].

It is possible that bDMARDs not only reduce disease activity but also affect autoantibody change in RA patients. While various bDMARDs had the potential to decrease the autoantibody levels, it was unclear what factors really effected on autoantibody change in RA patients. In addition, most studies reporting the effect of ABT on lowering autoimmune antibody levels have been conducted on patients with early RA [8,9]. We hypothesized that different results might be obtained in patients with established RA. The objective of this study was to evaluate the impact of ABT and other bDMARDs on autoantibody levels in patients with established RA in the AIRTIGHT (Can abatacept induce immunological remission under tight control in rheumatoid arthritis patient?) study.

 MATERIALS AND METHODS Study protocol

The AIRTIGHT study was a prospective, comparative non-randomized study to assess the clinical and immunological impacts of ABT and other bDMARDs on patients with established RA. Patients were treated at Osaka City University Hospital, Hamayu Hospital, or Kitade Hospital in Japan between May 2011 and May 2014. The primary endpoints were changes in autoantibody levels (ACPA, IgM-RF, IgG-RF, and anti-Gal (0) IgG) after 48 weeks treatment. This study was an investigator-initiated trial and treating physicians and patients were not blinded to the medication prescribed, but clinical parameters and outcomes were assessed during treatment by trained evaluators blinded to treatment groups and the clinical response of each patient.

 Patients

Eligible patients were ≥20 years old, fulfilled the American College of Rheumatology/European League Against Rheumatism classification criteria [12], had been treated for ≥3 months with any conventional synthetic DMARDs, and required treatment with bDMARDs including switching. We continued to register patients in the AIRTIGHT study to the point of 50 patients started on ABT. A total of 165 RA patients were enrolled to the AIRTIGHT study. At baseline, 50 patients were treated with ABT and 115 patients were treated with other bDMARDs. ABT was administered intravenously with the dose determined by body weight every 4 weeks for a total of 48 weeks. Other bDMARDs were administered in compliance with approved dosing methods and dosages. This study was registered with the University Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN000005570). This study was conducted after written informed consent was obtained from all study subjects in accordance with the Declaration of Helsinki, and the research protocol was approved by the Ethics Committee of Osaka City University Hospital (approval number: 2720, the name of the university is now changed to Osaka Metropolitan University).

 Assessment

Serum samples were collected and stored at –80°C until measurements from all patients before administration of bDMARDs at baseline and after 48 weeks of treatment. All the serum samples of patients were analyzed in a single session, and were measured at the same time for avoiding the error of measurement. We used the chemiluminescence enzyme immunoassay for ACPA (STACIA MEBlux test for CCP; Medical & Biological Laboratories Co., Ltd., Nagano, Japan), latex agglutination turbidimetry for IgM-RF (IATRO RF II; LSI Medience Corp., Tokyo, Japan), enzyme immunoassay for IgG-RF (Tokiwa measuring kit; Tokiwa Chemical Industries Co., Ltd., Tokyo, Japan), and electrochemiluminescence immunoassay for Anti-Gal (0) IgG (PICOLUMI CA•RF; Eisai Co., Ltd., Tokyo, Japan). Cut-off value was 4.5 U/mL in ACPA, 15 IU/mL in IgM-RF, 2.0 IU/mL in IgG-RF and 6.0 AU/mL in Anti-Gal (0) IgG. All of measurements were performed at LSI Medience Corporation.

 Propensity score matching

In this study, changes in autoantibody levels were compared between ABT group and non-ABT group. However, patients background such as sex, age, disease activity of RA and medication status were not matched. To overcome this problem, we used propensity score matching method. The propensity score matching method aims to balance the two groups with regard to their covariates. Sex, age, disease duration, disease activity score in 28 joints using C-reactive protein (DAS28-CRP), methotrexate dose, glucocorticoid dose, autoantibody levels (ACPA, IgM-RF, IgG-RF, and anti-Gal (0) IgG) at baseline, and previous bDMARDs use were chosen as matched factors.

 Statistical analysis

Data were expressed as median or percentage. Comparisons of baseline characteristics between groups were performed using the Mann-Whitney U-test or chi-square test. The Wilcoxson signed rank test was used to compare changes in ACPA, IgM-RF, IgG-RF, and anti-Gal (0) IgG levels, DAS28-CRP, the Simplified Disease Activity Index (SDAI), and the Clinical Disease Activity Index (CDAI) between baseline and 48 weeks after treatment. Comparisons of average dose of methotrexate, and glucocorticoid after 48 weeks treatment between groups were performed using the Mann-Whitney U-test. Comparisons of achieving DAS28-CRP remission rate after 48 weeks treatment between groups were performed using the chi-square test. Statistical significance was determined for values of p<0.05. All analyses were performed using Excel Statistics 2021 (SSRI, Social Survey Research Information Co., Tokyo, Japan).

 RESULTS Patient characteristics

One hundred four patients with RA (ABT, n=32; infliximab, n=10; etanercept, n=14; adalimumab, n=20; tocilizumab, n=19; golimumab, n=9) completed the study. Percentages continuing treatment were 64.0% in the ABT group and 75.7% in the non-ABT group, showing no significant difference (p=0.14). Adverse events were reported in 3 patients (severe anemia, sinusitis, and hives in 1 patient each) treated with ABT, and in 5 patients (pneumonia in 2 patients, and cancer of the tongue, arrhythmia, and myelodysplastic syndrome in 1 patient each) treated with non-ABT. Nine patients treated with ABT and 14 patients treated with non-ABT were switched bDMARDs for inadequate response. After propensity score matching, 25 patients with ABT and 25 patients with non-ABT (infliximab, n=1; etanercept, n=6; adalimumab, n=7; tocilizumab, n=7; golimumab, n=4) were finally analyzed (Figure 1). Baseline demographics and clinical characteristics were comparable between the ABT and non-ABT groups (Table 1). Before propensity score matching, methotrexate dose was lower (p=0.02) and glucocorticoid dose was higher (p=0.04) in ABT group compared to non-ABT group, and half of the patients in ABT group had a history of previous use of bDMARDs.

 Changes in autoantibody levels and disease activity

Median levels at baseline and 48 weeks were 62.7 and 57.8 U/mL for ACPA, 35.0 and 39.0 IU/mL for IgM-RF, 0.5 and 0.5 IU/mL for IgG-RF, and 50.4 and 53.5 AU/mL for anti-Gal (0) IgG, respectively, in ABT group (Figure 2). The changes of level in ACPA (p=0.22), IgM-RF (p=0.21), IgG-RF (p=0.19) and anti-Gal (0) IgG (p=0.22) were not significant after 48 weeks of ABT exposure. In non-ABT group, median levels at baseline and 48 weeks were 143.0 and 57.8 U/mL for ACPA (p=0.03), 50.0 and 37.0 IU/mL for IgM-RF (p<0.01), 0.6 and 0.5 IU/mL for IgG-RF (p=0.22), and 93.2 and 61.8 AU/mL for anti-Gal (0) IgG (p<0.01), respectively (Figure 2). In patients using anti-TNF inhibitors in non-ABT group (n=18), median levels at baseline and 48 weeks were 143.5 and 59.9 U/mL for ACPA (p=0.16), 87.0 and 43.5 IU/mL for IgM-RF (p<0.01), 0.6 and 0.6 IU/mL for IgG-RF (p=0.90), and 124.1 and 75.7 AU/mL for anti-Gal (0) IgG (p<0.01), respectively. In patients with tocilizumab in non-ABT group (n=7), median levels at baseline and 48 weeks were 143.0 and 46.2 U/mL for ACPA (p<0.05), 50.0 and 18.0 IU/mL for IgM-RF (p=0.35), 0.7 and 0.3 IU/mL for IgG-RF (p=0.09), and 61.6 and 19.0 AU/mL for anti-Gal (0) IgG (p=0.13), respectively. After 48 weeks of ABT treatment, no patient (0%) with ACPA, 1 patient (4.0%) with IgM-RF, 1 patient (4.0%) with IgG-RF, and 1 patient (4.0%) with anti-Gal (0) IgG showed seroconversion. In case of non-ABT treatment, no patient (0%) with ACPA, 3 patients (12.0%) with IgM-RF, 1 patient (4.0%) with IgG-RF, and no patient (0%) with anti-Gal (0) IgG showed seroconversion.

As shown in Figure 3, all composite measures of DAS28-CRP (Figure 3A), SDAI (Figure 3B), and CDAI (Figure 3C) significantly decreased after 48 weeks of treatment in both the ABT and non-ABT groups. Four patients in ABT group (16%) and 13 patients in non-ABT group (52%) achieved DAS28-CRP remission. The rate of achieving DAS28-CRP remission was significantly higher in non-ABT group than in ABT group (p=0.02). Even in patients who achieved DAS28-CRP remission with ABT treatment, decreases in ACPA (p=0.50), IgM-RF (p=0.50), and anti-Gal (0) IgG (p=0.46) were not significant, except IgG-RF (0.3 at baseline to 0.1 IU/mL at week 48, p=0.04). Similar results were obtained in the non-ABT group, where only IgM-RF (49.0 at baseline to 37.0 IU/mL at week 48, p<0.05) and anti-Gal (0) IgG (88.8 to 56.6 AU/mL, p=0.02) among the four autoantibodies showed a significant decrease even in patients who achieved remission.

Average dosage of methotrexate and glucocorticoid during 48 weeks treatment were 8.5±3.2 mg/weeks and 2.9±1.6 mg/day in ABT group, and 8.6±2.9 mg/weeks and 2.0±0.9 mg/day in non-ABT group. There were no differences in average dose of methotrexate (p=0.58) and glucocorticoid (p=0.37) between groups.

 DISCUSSION

Although previous studies such as ADJUST (Abatacept study to Determine the effectiveness in preventing the development of rheumatoid arthritis in patients with Undifferentiated inflammatory arthritis and to evaluate Safety and Tolerability) showed that treatment with ABT decreased serum levels of ACPA and RF in very early RA patients [8,9], our study revealed that autoantibody levels did not decrease during ABT treatment in patients with RA. Possible explanation for this inconsistency could be that subjects in our study were patients with established RA, whereas the ADJUST trial targeted patients with very early RA [8]. The autoimmune nature of RA has been clearly established, with involvement of both innate and adaptive immune systems. Inflammation of RA was involved multiple lymphoid cells in innate and adaptive responses. It was possible that these autoimmune systems change depending on time elapsed since onset. Sustained RF expression likely activates B-cells and monocytes, and cytokine profiles switched from T-cell to B-cell cytokines over 5 years [13]. Other study showed that T-cell cytokines are elevated in the synovial fluid of patients with RA within 3 months after symptom onset, but this profile was no longer present in established RA [14]. Previous longitudinal study that examined the fluctuations of ACPA levels for five years revealed that significant drop in ACPA levels was observed during the first year [15]. Those results suggest that T-cells play an important role particularly at early stage in RA. The ability of ABT to modulate the activation of T-cells, including naive T-cells, and the role of T-cells in initiating disease [6]. The effect of ABT on autoantibody may be more effective in the early stage of RA when T-cell is significantly activated.

Our study showed that autoantibody levels decreased during treatment with bDMARDs other than ABT. Cytokines were associated with disease duration of RA [13]. In ACPA positive RA patients, IL-6 and TNF begin to increase at pre-clinical phase and remain high even in chronic phase [16]. A pilot study showed that tocilizumab reduced ACPA levels for 24 weeks treatment in RA patients with not early stage (median disease duration: 3.6 years) [10]. Previous study demonstrated that tocilizumab treatment affected the frequency of pre-switch and post-switch memory B-cells in patients with RA [17]. The change in post-switch memory B-cells was negatively correlated with the change in naïve B-cells during treatment with tocilizumab, suggesting that tocilizumab has a potential to reduce ACPA production by affecting the balance of B-cell subpopulation in circulation and in lymphoid tissues [10]. IL-6 inhibitor has a potential to reduce autoantibody levels by affecting the distribution of B-cell subsets in circulation.

ACPA and IgM-RF decreased significantly in established RA patients (median disease duration: 10 years) with infliximab treatment for 1 year [11]. They reported that there was no relationship between change of autoantibody levels and disease activity or disease duration. The effects of anti-TNF inhibitor in RA have been attributed to the induction of apoptosis of inflammatory cells [18]. Citrullination is a post-translational modification of proteins in the apoptotic process and therefore anti-TNF could influence the formation and presence of antibodies against citrullinated proteins by directly interfering with the regulation of the apoptotic process [11]. In addition, previous study reported that anti-TNF inhibitor affected B-cell phenotype and IgD-CD27- memory B-cells in circulation [19]. The frequency of IgD-CD27- memory B-cells in circulation as well as IgM expression by IgD-CD27- memory B-cells were significantly decreased after anti-TNF inhibitor treatment in RA patients [19]. Considering these mechanisms, anti-TNF inhibitor has a potential to reduce autoantibody levels in established RA.

Some limitations must be considered when interpreting our findings. First, eligible patients were not allocated to groups randomly. It was possible that baseline imbalance between groups influenced the results even if adjustments were made by propensity score matching. Second, patient numbers were relatively small and small numbers of patients remained in the study over time. Therefore, we should work on further studies such as randomized controlled trials and large-scale ones. Finally, our analysis did not take into account the changes in concomitant medications or dosage changes during the observation period. Prospective studies considering time-dependent covariates should be planned in the future.

 CONCLUSION

In conclusion, autoantibody levels did not decrease during ABT treatment and decreased by non-ABT treatment in established RA.

 ACKNOWLEDGMENTS

We wish to thank Atsuko Kamiyama, Tomoko Nishimura and the Department of the Central Clinical Laboratory in Osaka Metropolitan University Medical School for collecting data and managing data quality. We greatly appreciate the cooperation of the patients with RA who participated in this study.

FUNDING

None.

CONFLICT OF INTEREST

SA has received speaking fees from Asahi Kasei, Astellas, AbbVie, Amgen, Chugai, Daiichi-Sankyo, Eisai, Eli Lilly, Gilead Sciences, Janssen, Mitsubishi Tanabe, Mochida, Novartis, Sanofi, Teijin, and UCB. KI has received speaking fees from Asahi-Kasei, Novartis Pharma, Mochida pharmaceutical Co., Ltd., and Medical view Co., Ltd. TO has received speaking fees from Asahi Kasei, Astellas, AbbVie, Amgen, Ayumi, Chugai, Daiichi-Sankyo, Eisai, Eli Lilly, Gilead Sciences, Janssen, Kyowa Kirin, Mitsubishi Tanabe, Novartis, Ono, Pfizer, Sanofi, Takeda, and UCB. TK has received speaking fees from AbbVie, Astellas Pharma Inc, Bristol-Myers Squibb, Chugai Pharmaceutical, Eisai, Janssen, Lilly, Mitsubishi Tanabe Pharma Corp., MSD, Ono Pharmaceutical, Pfizer, Roche, Takeda Pharmaceutical, Teijin Pharma, and UCB. All other authors have declared no conflicts of interest.

AUTHOR CONTRIBUTIONS

TK conception and design of study. All authors acquisition of data. SA and TK analysis data. SA drafting the manuscript. KI, MT, YS, TO, KM, and TK revising the manuscript.

 REFERENCES De RyckeL PeeneI HoffmanIE KruithofE UnionA MeheusL 2004 Rheumatoid factor and anticitrullinated protein antibodies in rheumatoid arthritis: diagnostic value, associations with radiological progression rate, and extra-articular manifestations Ann Rheum Dis 63 1587 93 10.1136/ard.2003.017574 15547083 PMC1754859 WalkerDJ PoundJD GriffithsID PowellRJ 1986 Rheumatoid factor tests in the diagnosis and prediction of rheumatoid arthritis Ann Rheum Dis 45 684 90 10.1136/ard.45.8.684 3488715 PMC1001968 SchellekensGA VisserH de JongBA van den HoogenFH HazesJM BreedveldFC 2000 The diagnostic properties of rheumatoid arthritis antibodies recognizing a cyclic citrullinated peptide Arthritis Rheum 43 155 63 10.1002/1529-0131(200001)43:1<155::AID-ANR20>3.0.CO;2-3 10643712 LuMC HsiehSC LaiNS LiKJ WuCH YuCL 2007 Comparison of anti-agalactosyl IgG antibodies, rheumatoid factors, and anti-cyclic citrullinated peptide antibodies in the differential diagnosis of rheumatoid arthritis and its mimics Clin Exp Rheumatol 25 716 21 WeismanMH DurezP HalleguaD ArandaR BeckerJC NuamahI 2006 Reduction of inflammatory biomarker response by abatacept in treatment of rheumatoid arthritis J Rheumatol 33 2162 6 GregersenPK SilverJ WinchesterRJ 1988 Genetic susceptibility to rheumatoid arthritis and human leukocyte antigen class II polymorphism. The role of shared conformational determinants Am J Med 85 6A 17 9 10.1016/0002-9343(88)90374-9 3059797 van der Helm-van MilAH VerpoortKN BreedveldFC HuizingaTW ToesRE de VriesRR 2006 The HLA-DRB1 shared epitope alleles are primarily a risk factor for anti-cyclic citrullinated peptide antibodies and are not an independent risk factor for development of rheumatoid arthritis Arthritis Rheum 54 1117 21 10.1002/art.21739 16572446 EmeryP DurezP DougadosM LegertonCW BeckerJC VratsanosG 2010 Impact of T-cell costimulation modulation in patients with undifferentiated inflammatory arthritis or very early rheumatoid arthritis: a clinical and imaging study of abatacept (the ADJUST trial) Ann Rheum Dis 69 510 6 10.1136/ard.2009.119016 19933744 PMC2927615 EndoY KogaT KawashiriSY MorimotoS NishinoA OkamotoM 2020 Anti-citrullinated protein antibody titre as a predictor of abatacept treatment persistence in patients with rheumatoid arthritis: a prospective cohort study in Japan Scand J Rheumatol 49 13 7 10.1080/03009742.2019.1627411 31402744 NoguchiA YasudaS HisadaR KatoM OkuK BohgakiT 2020 Anti-cyclic citrullinated peptide antibody titers decrease in rheumatoid arthritis patients treated with tocilizumab: a pilot study Mod Rheumatol 30 276 81 10.1080/14397595.2019.1583784 30789096 VisM BosWH WolbinkG VoskuylAE TwiskJW Van de StadtR 2008 IgM-rheumatoid factor, anti-cyclic citrullinated peptide, and anti-citrullinated human fibrinogen antibodies decrease during treatment with the tumor necrosis factor blocker infliximab in patients with rheumatoid arthritis J Rheumatol 35 425 8 AletahaD NeogiT SilmanAJ FunovitsJ FelsonDT BinghamCO3rd 2010 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative Arthritis Rheum 62 2569 81 10.1002/art.27584 20872595 DavisJM3rd CrowsonCS KnutsonKL AchenbachSJ StrausbauchMA TherneauTM 2020 Longitudinal relationships between rheumatoid factor and cytokine expression by immunostimulated peripheral blood lymphocytes from patients with rheumatoid arthritis: new insights into B-cell activation Clin Immunol 211 108342 10.1016/j.clim.2020.108342 31926330 PMC7045286 RazaK FalcianiF CurnowSJ RossEJ LeeCY AkbarAN 2005 Early rheumatoid arthritis is characterized by a distinct and transient synovial fluid cytokine profile of T cell and stromal cell origin Arthritis Res Ther 7 R784 95 10.1186/ar1733 15987480 PMC1175027 RönnelidJ WickMC LampaJ LindbladS NordmarkB KlareskogL 2005 Longitudinal analysis of citrullinated protein/peptide antibodies (anti-CP) during 5 year follow up in early rheumatoid arthritis: anti-CP status predicts worse disease activity and greater radiological progression Ann Rheum Dis 64 1744 9 10.1136/ard.2004.033571 15843452 PMC1755292 RidgleyLA AndersonAE PrattAG 2018 What are the dominant cytokines in early rheumatoid arthritis? Curr Opin Rheumatol 30 207 14 10.1097/BOR.0000000000000470 29206659 PMC5805125 RollP MuhammadK SchumannM KleinertS EinseleH DörnerT 2011 In vivo effects of the anti-interleukin-6 receptor inhibitor tocilizumab on the B cell compartment Arthritis Rheum 63 1255 64 10.1002/art.30242 21305508 ShenC MaertenP GeboesK Van AsscheG RutgeertsP CeuppensJL 2005 Infliximab induces apoptosis of monocytes and T lymphocytes in a human-mouse chimeric model Clin Immunol 115 250 9 10.1016/j.clim.2005.01.007 15893692 MouraRA QuaresmaC VieiraAR GonçalvesMJ Polido-PereiraJ RomãoVC 2017 B-cell phenotype and IgD-CD27- memory B cells are affected by TNF-inhibitors and tocilizumab treatment in rheumatoid arthritis PLoS One 12 e0182927 10.1371/journal.pone.0182927 28886017 PMC5590747 Figures and Table

Flow chart of patients. bDMARDs: biological disease-modifying anti-rheumatic drugs, ABT: abatacept, DAS28-CRP: disease activity score in 28 joints using C-reactive protein, ACPA: anticitrullinated protein antibodies, anti-Gal (0) IgG: anti-agalactosyl immunoglobulin G antibody, RF: rheumatoid factor.

Changes in autoantibody levels from baseline to 48 weeks. Changes in titers of ACPA (A), IgM-RF (B), IgG-RF (C), or anti-Gal (0) IgG (D) during 48 weeks. Data are presented as box plots. The box is drawn from 25th to 75th percentile with a horizontal line drawn inside it to denote the median. The mean is indicated by an x. The boundary of the lower whisker is the minimum value, and the upper whisker is the maximum value of the data set excluding any outliers. The Wilcoxson signed rank test was applied for testing changes over time. The open box indicates ABT group, and the shadow box indicates non-ABT group. ACPA: anticitrullinated protein antibodies, anti-Gal (0) IgG: anti-agalactosyl immunoglobulin G antibody, RF: rheumatoid factor, ABT: abatacept.

Changes in disease activity from baseline to 48 weeks. Changes in disease activity of DAS28-CRP (A), SDAI (B), or CDAI (C) after 48 weeks treatment. Data are presented as box plots. The box is drawn from 25th to 75th percentile with a horizontal line drawn inside it to denote the median. The mean is indicated by an x. The boundary of the lower whisker is the minimum value, and the upper whisker is the maximum value of the data set excluding any outliers. The Wilcoxson signed rank test was applied for testing changes over time. The open box indicates ABT group, and the shadow box indicates non-ABT group. CDAI: Clinical Disease Activity Index, DAS28-CRP: disease activity score in 28 joints using C-reactive protein, SDAI: Simplified Disease Activity Index, ABT: abatacept.

Baseline characteristics of subjects after propensity score matching

Abatacept (n=25) Non-abatacept (n=25) p-value
Female 22 (88) 22 (88) >0.99
Age (yr) 59.0 [54.0, 68.0] 62.0 [51.0, 69.0] 0.94
Disease duration of RA (yr) 8.0 [2.0, 15.0] 7.0 [2.0, 18.0] 0.84
DAS28-CRP 4.5 [3.7, 5.1] 4.4 [3.7, 5.1] 0.99
SDAI 20.9 [12.6, 28.5] 20.9 [15.1, 28.7] 0.99
CDAI 18.7 [11.3, 28.0] 19.8 [12.8, 28.2] 0.89
mHAQ 0.6 [0.3, 1.0] 0.8 [0.3, 1.0] 0.60
MMP-3 (ng/mL) 88.5 [53.4, 216.1] 78.2 [44.5, 173.6] 0.36
CRP (mg/dL) 0.7 [0.3, 1.3] 0.5 [0.2, 1.2] 0.93
ACPA-positive 19 (76) 24 (96) 0.10
IgM-RF-positive 16 (64) 23 (92) 0.04
IgG-RF-positive 4 (16) 4 (16) >0.99
Anti-Gal (0) IgG-positive 19 (76) 24 (96) 0.10
ACPA (U/mL) 62.7 [5.8, 141.0] 143.0 [38.0, 204.0] 0.16
IgM-RF (IU/mL) 35.0 [8.0, 158.0] 50.0 [41.0, 188.0] 0.14
IgG-RF (IU/mL) 0.5 [0.3, 1.3] 0.6 [0.5, 1.2] 0.52
Anti-Gal (0) IgG (AU/mL) 50.4 [7.5, 183.0] 93.2 [56.8, 226.0] 0.08
MTX use 21 (84) 19 (76) 0.73
MTX dose (mg/wk) 8.0 [6.0, 10.0] 8.0 [4.0, 10.0] 0.53
Glucocorticoid use 11 (44) 9 (36) 0.77
Glucocorticoid dose (mg/day) 0 [0.0, 3.0] 0 [0.0, 2.0] 0.50
Previous bDMARD use 12 (48) 11 (44) 0.99

Values are presented as number (%) or median [interquartile range]. Differences in quantitative variables between two groups were analyzed using the Mann-Whitney U-test. Differences in rate variables between two groups were analyzed by chi-square test. RA: rheumatoid arthritis, DAS28-CRP: disease activity score in 28 joints using C-reactive protein, SDAI: simplified disease activity index, CDAI: clinical disease activity index, mHAQ: modified health assessment questionnaire, MMP-3: matrix metalloproteinase-3, CRP: C-reactive protein, ACPA: anticitrullinated protein antibodies, anti-Gal (0) IgG: anti-agalactosyl immunoglobulin G antibody, RF: rheumatoid factor, MTX: methotrexate, bDMARD: biological disease-modifying anti-rheumatic drug.