Porphyromonas gingivalis, one of the major periodontalpathogens, is implicated in the initiation and progression ofperiodontal disease. The initial stages of periodontal inflammationare accompanied by vascular hyperpermeability.In our present study, we report that the P. gingivalislipopolysaccharide (LPS) increases the mRNA expression ofinterleukin-8 (IL-8), a major inducer of vascular permeability,in vascular endothelial cells. P. gingivalis LPS alsostimulated the induction of IL-8 secretion in endothelial cells.The P. gingivalis LPS-induced expression of IL-8 was primarilymodulated by nuclear factor-κB (NF-κB). P. gingivalisLPS significantly enhanced the vascular permeability bothin vitro and in vivo, and a blockade of the IL-8 receptordecreased the P. gingivalis LPS-induced vascular permeability.Taken together, these results suggest that P. gingivalisLPS increases vascular permeability through the NF-κBdependentproduction of IL-8 in vascular endothelial cells.