Background and objective: Little is known about the pathogenesis of apoptosis caused in cardiac tissues by periodontitis pathogens. The purpose of this study was to determine the related effect of periodontal pathogen Porphyromonas gingivalis on cardiac cell apoptosis.
Methods: DNA fragmentation, nuclear condensation and activated apoptotic caspases were measured by agarose gel electrophoresis, nuclear DAPI (4',6-diamidine-2-phenylindole dihydrochloride) stain and western blotting analysis following the surrounding medium of P. gingivalis and/or pre-administration of SB203580 (p38 inhibitor), U0126 [mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor], LY294002 [phosphoinositide 3-kinase (PI3K) inhibitor], cyclosporine A (CsA: calcineurin inhibitor), and Sp600125 [c-Jun N-terminal kinase (JNK) inhibitor] in cultured cardiac H9c2 cells.
Results: The surrounding medium of periodontal pathogen P. gingivalis increased DNA fragmentation, nuclear condensation and the activated apoptotic caspase-3, -8, and -9 proteins in H9c2 cells. DNA fragmentation and nuclear condensation of H9c2 cells treated with P. gingivalis medium were completely blocked by SB203580 plus U0126 and were decreased after pre-administration of SB203580 only, U0126 only, LY294002, CsA, but were increased by Sp600125.
Conclusion: Our findings suggest that the development of cardiac cell apoptosis can be directly induced by P. gingivalis medium. Porphyromonas gingivalis-related H9c2 cell apoptosis was mainly co-activated by p38 and ERK pathways and may be involved in death receptor-dependent (caspase 8) and mitochondria (caspase 9)-dependent apoptotic pathways. Porphyromonas gingivalis-related cardiac cell apoptosis was also partially mediated by PI3K or calcineurin signaling pathways, whereas the JNK pathway might play a protective role in P. gingivalis-related cardiac cell apoptosis.