Higher baseline global leukocyte DNA methylation is associated with MTX non-response in early RA patients.

Department of Clinical Chemistry, Erasmus MC, University Medical Center Rotterdam, P.O. Box 2040, 3000 CA, Rotterdam, The Netherlands. Department of Clinical Chemistry, Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands. Department of Clinical Chemistry, Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, Univ of Amsterdam, Amsterdam, The Netherlands. Department of Rheumatology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands. Academic Center of Excellence - Inflammunity, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands. Department of Clinical Chemistry, Erasmus MC, University Medical Center Rotterdam, P.O. Box 2040, 3000 CA, Rotterdam, The Netherlands. s.heil@erasmusmc.nl. Academic Center of Excellence - Inflammunity, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands. s.heil@erasmusmc.nl.

Arthritis research & therapy. 2019;(1):157
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Abstract

BACKGROUND Low-dose methotrexate (MTX) is the first-line therapy in early rheumatoid arthritis (eRA). Up to 40% of eRA patients do not benefit from MTX therapy. MTX has been shown to inhibit one-carbon metabolism, which is involved in the donation of methyl groups. In this study, we investigate baseline global DNA methylation and changes in DNA methylation during treatment in relation to clinical non-response after 3 months of MTX treatment. METHODS Two hundred ninety-four blood samples were collected from the Treatment in the Rotterdam Early Arthritis Cohort (tREACH, ISRCTN26791028), a multicenter, stratified single-blind clinical trial of eRA patients. Global DNA (hydroxy)methylation was quantified using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) and validated with a global DNA LINE-1 methylation technique. MTX response was determined as ΔDAS28. Additionally, patients were stratified into two response groups according to the European League Against Rheumatism (EULAR) response criteria. Associations between global DNA methylation and response were examined using univariate regression models adjusted for baseline DAS28, baseline erythrocyte folate levels, and body mass index (BMI). RESULTS Higher baseline global DNA methylation was associated with less decrease of DAS28 (β = 0.15, p = 0.013) and with MTX non-response (OR = 0.010, 95% CI = 0.001-0.188). This result was validated in LINE-1 elements (β = 0.22, p = 0.026). Changes in global DNA (hydroxy)methylation were not associated with MTX response over 3 months. CONCLUSIONS These results show that higher baseline global DNA methylation in treatment naïve eRA patients is associated with decreased clinical response after 3 months of treatment of eRA patients and can be further evaluated as a predictor for MTX therapy non-response. TRIAL REGISTRATION ISRCTN, ISRCTN26791028 , registered 23 August 2007-retrospectively registered.

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MeSH terms : DNA ; Leukocytes ; Methotrexate