Accumulating evidence has established that periodontitis was an independent risk factor for coronary heart disease (CAD). Porphyromonus gingivalis (P. gingivalis), a major periodontal pathogen, has already been shown to have a significant role in the inflammatory response of CAD in vivo. The aim of the present study was to identify whether P. gingivalis heat-shock protein 60 (HSP60) induced the dysfunction of human umbilical vein endothelial cells (HUVECs) in vitro. HUVECs were stimulated with a range of P. gingivalis HSP60 concentrations (1, 10 and 100 ng/l) at different time-points. The levels of vascular endothelial (VE)-cadherin, endothelial nitric oxide synthase (eNOS) and cysteinyl aspartate-specific protease-3 (caspase-3) were measured using western blot analysis. The apoptotic rate of HUVECs was detected using flow cytometry. P. gingivalis HSP60 at a concentration of 10 ng/l significantly decreased the expression levels of VE-cadherin and eNOS protein at 24 h stimulation, whereas no difference in these proteins was identified following a low dose of P. gingivalis HSP60 (1 ng/l). P. gingivalis HSP60 at 100 ng/l significantly downregulated the expression levels of VE-cadherin and eNOS protein at 12 h in HUVECs. However, the cleavage of caspase-3 showed an opposing change at different concentrations. Consistently, P. gingivalis HSP60 induced apoptosis of HUVECs in a concentration-dependent manner. These results indicated that P. gingivalis HSP60 may induce dysfunction and apoptosis in HUVECs via downregulating the expression levels of VE-cadherin and eNOS, and promoting the cleavage of caspase-3.
Keywords: E-cadherin; Porphyromonas gingivalis; apoptosis; endothelial nitric oxide synthase; heat-shock protein.