Abstract: Objective：To find out the mechanisms by which Porphyromonas gingivalis (P. gingivalis) regulates interleukin (IL)-8 expression in endothelial cells. Methods: P. gingivalis was applied to infect human umbilical vein endothelial cells (HUVECs), and the expressions of nucleotide binding oligomerization domain (NOD) 1, NOD2 and IL-8 were detected at mRNA and protein levels. Then the NOD1/NOD2 gene was silenced by RNA interference targeting NOD1 or NOD2 mRNA, followed by P. gingivalis treatment in the HUVECs, and the expression levels of NOD1/NOD2 and IL-8 were examined by real-time PCR, Western-blot or ELISA. In order to confirm the relationship between NOD1/NOD2 and IL-8 in the HUVECs, the agonists for NOD1 and NOD2, DAP and MDP were used in this study. Results: P. gingivalis was activated the expressions of NOD1 and NOD2 in the HUVECs. Meanwhile, IL-8 expression level was also upreguated after P. gingivalis treatment (P<0.01). Knocking down of NOD1 or NOD2, the expression level of NOD1 or NOD2 was decreased, and P. gingivalis-induced IL-8 expression was attenuated in the HUVECs (P<0.01). Compared with normal cells, the NOD1 and NOD2 agonists, DAP and MDP, successfully increased IL-8 expression respectively (P<0.05). Conclusion: NOD1 and NOD2 play an important role in the inflammation of HUVECs caused by P. gingivalis in the expression of IL8.

Key words: Interleukin-8, Porphyromonas gingivalis, Endothelial cells