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IgG Fc galactosylation predicts response to methotrexate in early rheumatoid arthritis

Authors
  • Lundström, Susanna L.1
  • Hensvold, Aase H.2, 3
  • Rutishauser, Dorothea1
  • Klareskog, Lars2, 3
  • Ytterberg, A. Jimmy1, 2
  • Zubarev, Roman A.1
  • Catrina, Anca I.2, 3
  • 1 Karolinska Institutet, Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Scheelesväg 2, Stockholm, SE 17177, Sweden , Stockholm (Sweden)
  • 2 Karolinska Institutet, Rheumatology Unit, Department of Medicine, Stockholm, Sweden , Stockholm (Sweden)
  • 3 Karolinska University Hospital, Rheumatology Unit, Stockholm, Sweden , Stockholm (Sweden)
Type
Published Article
Journal
Arthritis Research & Therapy
Publisher
Springer Science and Business Media LLC
Publication Date
Aug 09, 2017
Volume
19
Issue
1
Identifiers
DOI: 10.1186/s13075-017-1389-7
Source
Springer Nature
Keywords
License
Green

Abstract

BackgroundMethotrexate (MTX) is the standard first-line therapy in rheumatoid arthritis (RA) with variable clinical efficacy that is difficult to predict. The glycosylation status of immunoglobulin G (IgG) is altered in RA and influenced by MTX treatment. We aimed to further investigate if IgG glycosylation in untreated early RA can predict therapeutic response to MTX.MethodsWe used a shotgun proteomic approach to screen for the Fc glycopeptides in the serum of 12 control subjects and 59 untreated patients with early RA prior to and following MTX initiation. MTX treatment response was defined according to the European League Against Rheumatism at a median of 14 weeks (range 13–15) after treatment initiation. Seropositive patients were defined as those testing positive for anticitrullinated protein antibodies and/or rheumatoid factor at baseline (n = 44). Data analysis was performed using uni- and multivariate statistics.ResultsWe could confirm a low abundance of galactosylated glycans in untreated patients with early RA compared with control subjects that was partially restored by MTX treatment. This was more evident among future nonresponders than among responders to MTX treatment. Results were further validated and confirmed by multivariate statistical analysis of the baseline Fc glycan, proteomic, and clinical data. We found that the ratio between the main agalactosylated (FA2) and main mono- and di-galactosylated Fc glycans (FA2G1 and FA2G2) of IgG1 ranked as the most prominent factor distinguishing responders from nonresponders. A low baseline ratio of FA2/[FA2G1 + FA2G2]-IgG1 was associated with nonresponse (OR 5.3 [1.6–17.0]) and was able to discriminate future nonresponders from responders to MTX therapy with a sensitivity of 70% (95% CI 46–88%) and a specificity of 69% (95% CI 52–83%). For seropositive patients (n = 44), this trend was improved with a sensitivity of 73% (95% CI 45–92%) for nonresponse and a specificity of 79% (95% CI 60–92%).ConclusionsWe show that the FA2/[FA2G1 + FA2G2] of IgG1 is a biomarker candidate that is significantly associated with nonresponding patients and has potential value for prediction of MTX clinical response.

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