Abstract
BackgroundThe oral pathogen Porphyromonas gingivalis has been shown to modulate apoptosis in different cell types, but its effect on epithelial cells remains unclear.ResultsWe demonstrate that primary human gingival epithelial cells (HGECs) challenged with live P. gingivalis for 24 hours exhibit apoptosis, and we characterize this by M30 epitope detection, caspase-3 activity, DNA fragmentation and Annexin-V staining. Live bacteria strongly upregulated intrinsic and extrinsic apoptotic pathways. Pro-apoptotic molecules such as caspase-3, -8, -9, Bid and Bax were upregulated after 24 hours. The anti-apoptotic Bcl-2 was also upregulated, but this was not sufficient to ensure cell survival. The main P. gingivalis proteases arginine and lysine gingipains are necessary and sufficient to induce host cell apoptosis. Thus, live P. gingivalis can invoke gingival epithelial cell apoptosis in a time and dose dependent manner with significant apoptosis occurring between 12 and 24 hours of challenge via a gingipain-dependent mechanism.ConclusionThe present study provides evidence that live, but not heat-killed, P. gingivalis can induce apoptosis after 24 hours of challenge in primary human gingival epithelial cells. Either arginine or lysine gingipains are necessary and sufficient factors in P. gingivalis elicited apoptosis.
Highlights
The oral pathogen Porphyromonas gingivalis has been shown to modulate apoptosis in different cell types, but its effect on epithelial cells remains unclear
In vitro studies show that P. gingivalis can modulate apoptosis in the following cell types: fibroblasts [6,7], endothelial cells [8,9,10,11] and lymphocytes [12] and apoptosis has been proposed as a mechanism to explain the extensive tissue destruction in chronic periodontitis lesions
human gingival epithelial cells (HGECs) challenged with live P. gingivalis show early signs of apoptosis in a time- and dose-dependent manner HGECs were challenged with live or heat-killed P. gingivalis 33277 at an MOI:10, MOI:100 and MOI:1000 for 4 and 24 hours and M30 epitope detection was performed with immunohistochemistry
Summary
The oral pathogen Porphyromonas gingivalis has been shown to modulate apoptosis in different cell types, but its effect on epithelial cells remains unclear. Apoptosis or programmed cell death is triggered by two distinct signaling pathways; the intrinsic or stress-activated and the extrinsic or receptor-activated apoptotic pathway [3]. Both pathways activate their respective initiator caspases and converge to trigger executioner caspases (page number not for citation purposes). In vitro studies show that P. gingivalis can modulate apoptosis in the following cell types: fibroblasts [6,7], endothelial cells [8,9,10,11] and lymphocytes [12] and apoptosis has been proposed as a mechanism to explain the extensive tissue destruction in chronic periodontitis lesions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
