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Specific interaction between genotype, smoking and autoimmunity to citrullinated α-enolase in the etiology of rheumatoid arthritis

Nature Genetics volume 41, pages 13191324 (2009) | Download Citation

This article has been updated


Gene-environment associations are important in rheumatoid arthritis (RA) susceptibility, with an association existing between smoking, HLA- DRB1 'shared epitope' alleles, PTPN22 and antibodies to cyclic citrullinated peptides(CCP)1,2. Here, we test the hypothesis that a subset of the anti-CCP response, with specific autoimmunity to citrullinated α-enolase3,4, accounts for an important portion of these associations. In 1,497 individuals from three RA cohorts, antibodies to the immunodominant citrullinated α-enolase CEP-1 epitope4 were detected in 43–63% of the anti-CCP–positive individuals, and this subset was preferentially linked to HLA-DRB1*04. In a case-control analysis of 1,000 affected individuals and 872 controls, the combined effect of shared epitope, PTPN22 and smoking showed the strongest association with the anti-CEP-1–positive subset (odds ratio (OR) of 37, compared to an OR of 2 for the corresponding anti-CEP-1–negative, anti-CCP–positive subset). We conclude that citrullinated α-enolase is a specific citrullinated autoantigen that links smoking to genetic risk factors in the development of RA.

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  • 26 November 2009

    In the version of this article initially published, the x–axes of Figure 4 panels A–C were incorrectly labeled. The error has been corrected in the HTML and PDF versions of the article.


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The authors wish to acknowledge M. Andersson, M. Mullazhi and M. Widhe for their input regarding the development of the anti-CEP-1 ELISA. We would also like to thank investigators and study participants from the EIRA, the NR and the NOAR studies for their contributions. This work was supported by grants from the Arthritis Research Campaign, the Swedish Research Council, the Swedish Council for Working Life and Social Research, the Arbetsmarknadens Försäkrings Aktibebolag insurance foundation, the US National Institutes of Health (grant P60 AR047782), FAMRI (Flight Attendants Medical Research Institute), the Swedish Rheumatism Association, King Gustav V's 80-year foundation and the Swedish Fund for Research Without Animal Experiments. This study is part of the EU funded research project AutoCure, within the sixth framework program.

Author information

Author notes

    • Hiba Mahdi
    •  & Benjamin A Fisher

    These authors contributed equally to this work.


  1. Rheumatology Unit, Karolinska Institutet, Center for Molecular Medicine, Stockholm, Sweden.

    • Hiba Mahdi
    • , Vivianne Malmström
    • , Leonid Padyukov
    •  & Lars Klareskog
  2. Kennedy Institute of Rheumatology, Imperial College London, London, UK.

    • Benjamin A Fisher
    • , Peter Charles
    • , Patrick J Venables
    •  & Karin Lundberg
  3. Institute for Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.

    • Henrik Källberg
    • , Bo Ding
    •  & Lars Alfredsson
  4. Arthritis Research Campaign Epidemiology Unit, University of Manchester, Manchester, UK.

    • Darren Plant
    •  & Deborah P M Symmons
  5. Unit of Clinical Immunology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.

    • Johan Rönnelid


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H.M. performed ELISA assays on EIRA, performed statistical analyses and produced the figures. B.F. performed ELISA assays on NR and NOAR, performed statistical analyses and contributed to writing of the paper. H.K. performed statistical analyses on EIRA, produced the tables and contributed to the writing of the Supplementary Note and Methods sections. D.P. performed statistical analyses and HLA-DRB1 genotyping on NR and NOAR. V.M. supervised laboratory experiments and supervised statistical analysis on EIRA. J.R. developed the CEP-1 ELISA. P.C. supervised laboratory experiments on NR and NOAR. B.D. performed the SNP analyses. L.A. supervised statistical analyses on EIRA and wrote the Supplementary Note and Methods section on interaction analyses. L.P. performed the HLA-DRB1 and PTPN22 genotyping on EIRA. D.P.M.S. is responsible for the NOAR study and supervised statistical analyses on NR and NOAR. P.J.V. designed the study and supervised laboratory experiments on NR and NOAR. L.K. is responsible for the EIRA study and the design of the study. K.L. performed ELISA assays on NR and NOAR, designed the study and wrote the paper. All authors contributed to the final paper.

Competing interests

A patent for the diagnostic use of the CEP-1 peptide (patent application number: WO0890360, published on 31 July 2008) is jointly held by two of the authors (P.J.V. and K.L.) and funded by Imperial Innovations, Imperial College London.

Corresponding author

Correspondence to Karin Lundberg.

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    Supplementary Tables 1–3 and Supplementary Note

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