title: Effect of Porphyromonas gingivalis-induced inflammation on the development of rheumatoid arthritis.
abstract: BACKGROUND
  Periodontitis is an extra-synovial chronic inflammatory condition, which has been proposed to be inter-related with rheumatoid arthritis.
  
  
  OBJECTIVE
  We investigated the effect of an established extra-synovial chronic inflammatory lesion on the induction and severity of experimental arthritis.
  
  
  METHODS
  Chronic inflammatory lesions were induced by the implantation of polyurethane sponges impregnated with heat-killed Porphyromonas gingivalis into the backs of DA rats. Thirty-five days later, adjuvant arthritis (AA) was induced in the rats by injecting a mycobacterium cell wall in complete Freund's adjuvant. The development of arthritis was then monitored for 2 weeks.
  
  
  RESULTS
  Histological assessment of the implanted sponges confirmed that a chronic inflammatory lesion had been established after 21 days. Following induction of adjuvant arthritis, the severity of disease was scored and paw swelling was measured. Severe arthritis developed more rapidly in animals with a pre-existing P. gingivalis-induced inflammatory lesion elsewhere.
  
  
  CONCLUSIONS
  The results show that a pre-existing extra-synovial chronic inflammatory lesion induced by P. gingivalis promotes the development of arthritis in an animal model. These findings provide further evidence for a relationship between the presence of periodontal pathogen-associated inflammation and the development of rheumatoid arthritis.
authors.affiliation: School of Dentistry, Faculty of Health Sciences, School of Medical Sciences, University of Adelaide, Adelaide, Australia. mark.bartold@adelaide.edu.au
authors.forename: P Mark
authors.initials: PM
authors.lastname: Bartold
authors.forename: Victor
authors.initials: V
authors.lastname: Marino
authors.forename: Melissa
authors.initials: M
authors.lastname: Cantley
authors.forename: David R
authors.initials: DR
authors.lastname: Haynes
mesh_terms: D000818:Animals; D001169:Arthritis, Experimental / Q000209:etiology*; D001172:Arthritis, Rheumatoid / Q000150:complications*; D016866:Bacteroidaceae Infections / Q000150:complications* / Q000382:microbiology; D002908:Chronic Disease; D004195:Disease Models, Animal; D018450:Disease Progression; D005260:Female; D006614:Hindlimb; D007249:Inflammation / Q000150:complications / Q000382:microbiology*; D016966:Porphyromonas gingivalis / Q000472:pathogenicity; D051381:Rats; D011919:Rats, Inbred Strains; D040521:Subcutaneous Tissue