Heightened immune response to autocitrullinated porphyromonas gingivalis peptidylarginine deiminase: a potential mechanism for breaching immunologic tolerance in rheumatoid arthritis

Quirke, A.-M. et al. (2013) Heightened immune response to autocitrullinated porphyromonas gingivalis peptidylarginine deiminase: a potential mechanism for breaching immunologic tolerance in rheumatoid arthritis. Annals of the Rheumatic Diseases, 73(1), pp. 263-269. (doi:10.1136/annrheumdis-2012-202726)

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Publisher's URL: http://dx.doi.org/10.1136/annrheumdis-2012-202726

Abstract

<p>Background: Rheumatoid arthritis (RA) is characterised by autoimmunity to citrullinated proteins, and there is increasing epidemiologic evidence linking Porphyromonas gingivalis to RA. P gingivalis is apparently unique among periodontal pathogens in possessing a citrullinating enzyme, peptidylarginine deiminase (PPAD) with the potential to generate antigens driving the autoimmune response.</p> <p>Objectives: To examine the immune response to PPAD in patients with RA, individuals with periodontitis (PD) and controls (without arthritis), confirm PPAD autocitrullination and identify the modified arginine residues.</p> <p>Methods: PPAD and an inactivated mutant (C351A) were cloned and expressed and autocitrullination of both examined by immunoblotting and mass spectrometry. ELISAs using PPAD, C351A and another P gingivalis protein arginine gingipain (RgpB) were developed and antibody reactivities examined in patients with RA (n=80), individuals with PD (n=44) and controls (n=82).</p> <p>Results: Recombinant PPAD was a potent citrullinating enzyme. Antibodies to PPAD, but not to Rgp, were elevated in the RA sera (median 122 U/ml) compared with controls (median 70 U/ml; p<0.05) and PD (median 60 U/ml; p<0.01). Specificity of the anti-peptidyl citrullinated PPAD response was confirmed by the reaction of RA sera with multiple epitopes tested with synthetic citrullinated peptides spanning the PPAD molecule. The elevated antibody response to PPAD was abolished in RA sera if the C351A mutant was used on ELISA.</p> <p>Conclusions: The peptidyl citrulline-specific immune response to PPAD supports the hypothesis that, as a bacterial protein, it might break tolerance in RA, and could be a target for therapy.</p>

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Culshaw, Dr Shauna
Authors: Quirke, A.-M., Lugli, E.B., Wegner, N., Hamilton, B.C., Charles, P., Chowdhury, M., Ytterberg, A.J., Zubarev, R.A., Potempa, J., Culshaw, S., Guo, Y., Fisher, B.A., Thiele, G., Mikuls, T.R., and Venables, P.J.
College/School:College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing > Dental School
Journal Name:Annals of the Rheumatic Diseases
Publisher:B M J Group
ISSN:0003-4967
ISSN (Online):1468-2060
Copyright Holders:Copyright © 2013 The Authors
First Published:First published in Annals of the Rheumatic Diseases
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
535611Gums and JointsShauna CulshawEuropean Commission (EC)261460SM - DENTAL SCHOOL