IADR Abstract Archives
Effect of P. gingivalis-derived Phosphoglycerol Lipid on Platelet Aggregation
Objectives: Because the keystone pathobiont, Porphyromonas gingivalis (Pg), requires hemin for growth, it is possible that Pg may attenuate the host’s blood clotting system to increase bacterial access to blood. However, the effects of Pg on the blood clotting system remain elusive. Phosphoglycerol Dihydroceramide (PGDHC) lipids represent cell-membrane-permeable lipids produced by Pg that promote osteoclastogenesis by acting on non-muscle myosin II-A (Myh9) (Kanzaki et al., BBA Mol Cell Biol Lipids. 2017). Mutation of Myh9 causes malfunction of platelet aggregation (MYH9-related disorders), suggesting that PGDHC’s effect on Myh9 may include inhibition of platelet aggregation. The present study investigated the effect of PGDHC on platelet aggregation in vitro.
Methods: Platelet-rich plasma (PRP) purchased from (FirstChoice Bio) was treated with concentrations of Escherichia coli lipopolysaccharide (E. coli-LPS), Pg-LPS, PGDHC, or Pg-Phosphoethanolamine Dihydroceramides (PEDHC) for one hour at 37 Celcius. Whole fixed bacteria (10^8/ml) and sonic-supernatant of P. gingivalis (33277) and A. actinomycetemcomitans (JP2) were also for pretreatments. After the above-noted pretreatments, thrombin (3 U/ml) was applied to induce platelet aggregation. Platelet aggregometry was performed using a plate reader (Synergy HT) at OD 410nm and 595nm. All treatments were carried out in triplicate and repeated at least twice. The results were analyzed using ANOVA with a Tukey post hoc test for pairwise comparisons.
Results: Whole fixed A. actinomycetemcomitans, but not its supernatant, promoted thrombin-induced platelet aggregation. P. gingivalis supernatant, but not whole fixed Pg bacteria, significantly inhibited thrombin-induced platelet aggregation (P<0.05), suggesting that a soluble component in P. gingivalis may inhibit platelet aggregation. PGDHC, but not E. coli-LPS, Pg-LPS or PEDHC significantly inhibited the thrombin-induced platelet aggregation (P<0.05).
Conclusions: For the first time, we demonstrate that Pg produces a virulence factor, i.e., PGDHC, that inhibits platelet aggregation, providing a potential mechanism for the access of Pg to blood in periodontitis.
Methods: Platelet-rich plasma (PRP) purchased from (FirstChoice Bio) was treated with concentrations of Escherichia coli lipopolysaccharide (E. coli-LPS), Pg-LPS, PGDHC, or Pg-Phosphoethanolamine Dihydroceramides (PEDHC) for one hour at 37 Celcius. Whole fixed bacteria (10^8/ml) and sonic-supernatant of P. gingivalis (33277) and A. actinomycetemcomitans (JP2) were also for pretreatments. After the above-noted pretreatments, thrombin (3 U/ml) was applied to induce platelet aggregation. Platelet aggregometry was performed using a plate reader (Synergy HT) at OD 410nm and 595nm. All treatments were carried out in triplicate and repeated at least twice. The results were analyzed using ANOVA with a Tukey post hoc test for pairwise comparisons.
Results: Whole fixed A. actinomycetemcomitans, but not its supernatant, promoted thrombin-induced platelet aggregation. P. gingivalis supernatant, but not whole fixed Pg bacteria, significantly inhibited thrombin-induced platelet aggregation (P<0.05), suggesting that a soluble component in P. gingivalis may inhibit platelet aggregation. PGDHC, but not E. coli-LPS, Pg-LPS or PEDHC significantly inhibited the thrombin-induced platelet aggregation (P<0.05).
Conclusions: For the first time, we demonstrate that Pg produces a virulence factor, i.e., PGDHC, that inhibits platelet aggregation, providing a potential mechanism for the access of Pg to blood in periodontitis.