Peptidylarginine deiminase from Porphyromonas gingivalis contributes to infection of gingival fibroblasts and induction of prostaglandin E2‐signaling pathway

Summary Porphyromonas gingivalis (P. gingivalis) expres‐ses the enzyme peptidylarginine deiminase (PPAD), which has a strong preference for C‐terminal arginines. Due to the combined activity of PPAD and Arg‐specific gingipains, P. gingivalis on the cell surface is highly citrullinated. To investigate the contribution of PPAD to the interaction of P. gingivalis with primary human gingival fibroblasts (PHGF) and P. gingivalis‐induced synthesis of prostaglandin E2 (PGE2), PHGF were infected with wild‐type P. gingivalis ATCC 33277, an isogenic PPAD‐knockout strain (∆ppad) or a mutated strain (C351A) expressing an inactive enzyme in which the catalytic cysteine has been mutated to alanine (PPADC351A). Cells were infected in medium containing the mutants alone or in medium supplemented with purified, active PPAD. PHGF infection was assessed by colony‐forming assay, microscopic analysis and flow cytometry. Expression of cyclo‐oxygenase 2 (COX‐2) and microsomal PGE synthase‐1 (mPGES‐1), key factors in the prostaglandin synthesis pathway, was examined by quantitative reverse transcription polymerase chain reaction (qRT‐PCR), while PGE2 synthesis was evaluated by enzyme immunoassay. PHGF were infected more efficiently by wild‐type P. gingivalis than by the ∆ppad strain, which correlated with strong induction of COX‐2 and mPGES‐1 expression by wild‐type P. gingivalis, but not by the PPAD activity‐null mutant strains (Δppad and C351A). The imp...
Source: Oral Microbiology and Immunology - Category: Microbiology Authors: Tags: Original Article Source Type: research