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Defining the role of Porphyromonas gingivalis peptidylarginine deiminase (PPAD) in rheumatoid arthritis through the study of PPAD biology.

ABSTRACT: Antibodies to citrullinated proteins are a hallmark of rheumatoid arthritis (RA). Porphyromonas gingivalis peptidylarginine deiminase (PPAD) has been implicated in the initiation of RA by generating citrullinated neoantigens and due to its ability to autocitrullinate.To define the citrullination status and biology of PPAD in P gingivalis and to characterise the anti-PPAD antibody response in RA and associated periodontal disease (PD).PPAD in P gingivalis cells and culture supernatant were analysed by immunoblotting and mass spectrometry to detect citrullination. Recombinant PPAD (rPPAD), inactive mutant PPAD (rPPAD(C351S)), and N-terminal truncated PPAD (rPPAD(Ntx)) were cloned and expressed in Escherichia coli. Patients with RA and healthy controls were assayed for IgG antibodies to citrullinated rPPAD and unmodified rPPAD(C351S) by ELISA. Anti-PPAD antibodies were correlated with anti-cyclic citrullinated peptide (third-generation) antibody levels, RA disease activity and PD status.PPAD from P gingivalis is truncated at the N-terminal and C-terminal domains and not citrullinated. Only when artificially expressed in E coli, full-length rPPAD, but not truncated (fully active) rPPAD(Ntx), is autocitrullinated. Anti-PPAD antibodies show no heightened reactivity to citrullinated rPPAD, but are exclusively directed against the unmodified enzyme. Antibodies against PPAD do not correlate with anti-cyclic citrullinated peptide levels and disease activity in RA. By contrast, anti-PPAD antibody levels are significantly decreased in RA patients with PD.PPAD autocitrullination is not the underlying mechanism linking PD and RA. N-terminal processing protects PPAD from autocitrullination and enhances enzyme activity. Anti-PPAD antibodies may have a protective role for the development of PD in patients with RA.

SUBMITTER: Konig MF

PROVIDER: S-EPMC4368502 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Defining the role of Porphyromonas gingivalis peptidylarginine deiminase (PPAD) in rheumatoid arthritis through the study of PPAD biology.

Konig Maximilian F MF Paracha Alizay S AS Moni Malini M Bingham Clifton O CO Andrade Felipe F

Annals of the rheumatic diseases 20140526 11

<h4>Background</h4>Antibodies to citrullinated proteins are a hallmark of rheumatoid arthritis (RA). Porphyromonas gingivalis peptidylarginine deiminase (PPAD) has been implicated in the initiation of RA by generating citrullinated neoantigens and due to its ability to autocitrullinate.<h4>Objectives</h4>To define the citrullination status and biology of PPAD in P gingivalis and to characterise the anti-PPAD antibody response in RA and associated periodontal disease (PD).<h4>Methods</h4>PPAD in ...[more]

PMID: 24864075

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Project description:ObjectivesTo investigate the suggested role of Porphyromonas gingivalis peptidylarginine deiminase (PAD) in the relationship between the aetiology of periodontal disease and experimentally induced arthritis and the possible association between these two conditions.MethodsA genetically modified PAD-deficient strain of P. gingivalis W50 was produced. The effect of this strain, compared to the wild type, in an established murine model for experimental periodontitis and experimental arthritis was assessed. Experimental periodontitis was induced following oral inoculation with the PAD-deficient and wild type strains of P. gingivalis. Experimental arthritis was induced via the collagen antibody induction process and was monitored by assessment of paw swelling and micro-CT analysis of the radio-carpal joints. Experimental periodontitis was monitored by micro CT scans of the mandible and histological assessment of the periodontal tissues around the mandibular molars. Serum levels of anti-citrullinated protein antibodies (ACPA) and P. gingivalis were assessed by ELISA.ResultsThe development of experimental periodontitis was significantly reduced in the presence of the PAD-deficient P. gingivalis strain. When experimental arthritis was induced in the presence of the PAD-deficient strain there was less paw swelling, less erosive bone damage to the joints and reduced serum ACPA levels when compared to the wild type P. gingivalis inoculated group.ConclusionThis study has demonstrated that a PAD-deficient strain of P. gingivalis was associated with significantly reduced periodontal inflammation. In addition the extent of experimental arthritis was significantly reduced in animals exposed to prior induction of periodontal disease through oral inoculation of the PAD-deficient strain versus the wild type. This adds further evidence to the potential role for P. gingivalis and its PAD in the pathogenesis of periodontitis and exacerbation of arthritis. Further studies are now needed to elucidate the mechanisms which drive these processes.

Dataset Information

Defining the role of Porphyromonas gingivalis peptidylarginine deiminase (PPAD) in rheumatoid arthritis through the study of PPAD biology.

Publications

Defining the role of Porphyromonas gingivalis peptidylarginine deiminase (PPAD) in rheumatoid arthritis through the study of PPAD biology.

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