The peptidylarginine deiminase gene is a conserved feature of Porphyromonas gingivalis.

Giorgio Gabarrini,Johanna Westra,Jan Maarten Van Dijl,Arie Jan Van Winkelhoff,Kai Zhou,Tim Stobernack,Arjan Vissink,Elisabeth Brouwer,Menke De Smit,John W A Rossen

doi:10.1038/srep13936

Giorgio Gabarrini, Johanna Westra + Show 8 more

Open Access

https://doi.org/10.1038/srep13936

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Abstract

Periodontitis is an infective process that ultimately leads to destruction of the soft and hard tissues that support the teeth (the periodontium). Periodontitis has been proposed as a candidate risk factor for development of the autoimmune disease rheumatoid arthritis (RA). Porphyromonas gingivalis, a major periodontal pathogen, is the only known prokaryote expressing a peptidyl arginine deiminase (PAD) enzyme necessary for protein citrullination. Antibodies to citrullinated proteins (anti-citrullinated protein antibodies, ACPA) are highly specific for RA and precede disease onset. Objective of this study was to assess P. gingivalis PAD (PPAD) gene expression and citrullination patterns in representative samples of P. gingivalis clinical isolates derived from periodontitis patients with and without RA and in related microbes of the Porphyromonas genus. Our findings indicate that PPAD is omnipresent in P. gingivalis, but absent in related species. No significant differences were found in the composition and expression of the PPAD gene of P. gingivalis regardless of the presence of RA or periodontal disease phenotypes. From this study it can be concluded that if P. gingivalis plays a role in RA, it is unlikely to originate from a variation in PPAD gene expression.

Highlights

Periodontitis is an infective process that leads to destruction of the soft and hard tissues that support the teeth
This is the first study assessing P. gingivalis PAD (PPAD) expression in a large sample of clinical P. gingivalis isolates obtained from patients with or without rheumatoid arthritis (RA)
Our findings indicate that PPAD is omnipresent in P. gingivalis, but absent from P. endodontalis and P. asaccharolytica as well as from the other periodontal pathogens studied

Summary

Introduction

Periodontitis is an infective process that leads to destruction of the soft and hard tissues that support the teeth (the periodontium). Periodontitis has been proposed as a candidate risk factor for development of the autoimmune disease rheumatoid arthritis (RA). Porphyromonas gingivalis, a major periodontal pathogen, is the only known prokaryote expressing a peptidyl arginine deiminase (PAD) enzyme necessary for protein citrullination. Citrullination is a post-translational modification catalyzed by a family of enzymes called peptidylarginine deiminases (PAD)[5]. In this reaction, an arginine residue within a protein is converted into the non-coded amino acid citrulline. Porphyromonas gingivalis is a major periodontal pathogen involved in destructive periodontal disease[6] and is the only known prokaryote expressing a PAD enzyme[7]. PPAD has been reported to be able to generate citrullinated forms of various arginine-containing proteins and peptides[8], among which are human fibrinogen and human α -enolase, two candidate auto-antigens in RA12

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