Artikel
The role of anti-acetylated peptide antibodies (AAPA) in rheumatoid arthritis patients starting their first DMARD treatment on methotrexate
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Autoren
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Paul Studenic
- Medizinische Universität Wien, Klinik für Innere Medizin 3, Abteilung für Rheumatologie und Geriatrie, Wien, Österreich
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Stephan Blüml
- Medizinische Universität Wien, Universitätsklinik für Innere Medizin III, Wien, Österreich
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Holger Bang
- ORGENTEC Diagnostika GmbH, Mainz
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Manuel Unger
- Medizinische Universität Wien, Klinik für Innere Medizin 3; Abteilung für Rheumatologie, Wien, Österreich
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Karim Raza
- University of Birmingham, Institute of Inflammation and Ageing, Birmingham, United Kingdom
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Daniel Aletaha
- Medizinische Universität Wien, Klinik für Innere Medizin 3, Abteilung für Rheumatologie, Wien, Österreich
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Josef Smolen
- Dept. of Internal Medicine III, Medical University Vienna, Wien, Österreich
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Günter Steiner
- Medizinische Universiät Wien, Klinik für Innere Medizin 3, Abteilung für Rheumatologie, Wien, Österreich
| Veröffentlicht: | 29. August 2016 |
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Gliederung
Text
Background: Anti-acetylated-peptide antibodies (AAPA) have recently been described in rheumatoid arthritis (RA) patients and may be used as a further diagnostic marker in patients with undifferentiated arthritis.
In this study we aimed to determine the prevalence of AAPA in a cohort of RA patients starting their first conventional synthetic DMARD treatment (csDMARD) and additionally evaluated the usefulness of AAPA as potential predictors of clinical response to methotrexate (MTX) therapy.
Methods: We measured IgG and IgA AAPA by ELISA using two acetylated peptides derived from vimentin. We tested by regression, parametric and non-parametric analyses of disease activity measures if AAPA show potency for predicting response to MTX.
Results: IgG and/or IgA AAPA were detected in 74.5% of the 110 RA patients who stated MTX treatment: 49% were positive for either IgA or IgG antibodies and 25.5% were IgA/IgG double positive. In the AAPA positive patients, 73.6% were positive for IgG AAPA while 26.4% showed IgA antibodies. Importantly, of the 36.4% of patients negative for both RF and ACPA (double negative), 55% were positive for IgG and/or IgA AAPA, and the remaining patients (i.e. 16% of the total cohort) were completely seronegative (triple-negative), see Table 1 [Tab. 1]. When comparing triple negative patients with the AAPA positive double-negative ones, no significant difference in baseline characteristics was found but a trend that patients with more seroreactivities showed higher composite disease activity scores. Analyzing the clinical response to MTX, IgG-AAPA positive double-negative patients showed a significantly greater relative SDAI change after 6 months compared to triple-negative patients (p=0.028; median (IQR): -44.6% (-58.5 - -28.90) vs. 5.26% (-23.9 - 55.5%). In addition, there was a significantly greater relative change in CRP and erythrocyte sedimentation rate in AAPA positive double-negative patients .
Conclusion: IgG AAPA commonly occur in RA patients . Measuring AAPA in addition to RF and ACPA reduced the prevalence of seronegative patients by more than 50 %. These AAPA positive but RF and ACPA negative patients responded significantly better to MTX. Therefore, AAPA positivity in RF and ACPA negative patients identifies a subgroup of patients with a more favourable response to MTX.
