Distribution of Porphyromonas gingivalis fimA genotypes in patients affected by rheumatoid arthritis and periodontitis.

OBJECTIVE: To determine and compare the distribution of Porphyromonas gingivalis fimA genotypes in patients affected by Rheumatoid arthritis (RA) and periodontitis (PE). MATERIALS AND METHODS: This study involved 394 subjects divided into four groups, RA, PE, RA and PE and healthy subjects. PE was diagnosed by using clinical attachment loss (CAL) and probing depth (PD) indexes. Presence of P. gingivalis and its genotypes was identified by polymerase chain reaction in subgingival biofilm. RESULTS: P. gingivalis was more frequent in patients with RA (82.69%), and fimA II genotype was the most frequent in all groups, especially in PE/RA (76.71%). There was statistical difference (p < .05) regarding the frequency of P. gingivalis genotypes such as fimA Ib, II and III. CONCLUSIONS: Distribution of P. gingivalis fimA II genotypes was different among groups, it could play a critical role in the presence of PE in RA patients.

Porphyromonas gingivalis fimbriae dampen P2X7-dependent interleukin-1ß secretion.

Porphyromonas gingivalis is a major contributor to the pathogenesis of periodontitis, an infection-driven inflammatory disease that leads to bone destruction. This pathogen stimulates pro-interleukin (IL)-1ß synthesis but not mature IL-1ß secretion, unless the P2X7 receptor is activated by extracellular ATP (eATP). Here, we investigated the role of P. gingivalis fimbriae in eATP-induced IL-1ß release. Bone marrow-derived macrophages (BMDMs) from wild-type (WT) or P2X7-deficient mice were infected with P. gingivalis (381) or isogenic fimbria-deficient (DPG3) strain with or without subsequent eATP stimulation. DPG3 induced higher IL-1ß secretion after eATP stimulation compared to 381 in WT BMDMs, but not in P2X7-deficient cells. This mechanism was dependent on K(+) efflux and Ca(2+)-independent phospholipase A2 activity. Accordingly, non-fimbriated P. gingivalis failed to inhibit apoptosis via the eATP/P2X7 pathway. Furthermore, P. gingivalis-driven stimulation of IL-1ß was Toll-like receptor 2 and MyD88 dependent, and not associated with fimbria expression. Fimbria-dependent down-modulation of IL-1ß was selective, as levels of other cytokines remained unaffected by P2X7 deficiency. Confocal microscopy demonstrated the presence of discrete P2X7 expression in the absence of P. gingivalis stimulation, which was enhanced by 381-stimulated cells. Notably, DPG3-infected macrophages revealed a distinct pattern of P2X7 receptor expression with a marked focus formation. Collectively, these data demonstrate that eATP-induced IL-1ß secretion is impaired by P. gingivalis fimbriae in a P2X7-dependent manner.