| ObjectivesPorphyromonas gingivalis (P. gingivalis) is thought to be one of the most important pathogens in periodontitis, especially in chronic adult periodontitis and early-onset periodontitis. Many reports showed that the progress of chronic adult periodontitis is closely related with P. gingivalis , which exists in subgingi-val plaque in periodontitis patients. P. gingivalis influences the expression of many inflammatory cytokines in various cells in periodontal tissue, and these cy-tokines are very important for initiation and development of periodontitis. However, we know a little on the pathogenesis of periodontitis induced by P. gingivalis . A body of research revealed that P. gingivalis processes many virulent factors, including fimbri, out-membrane protein, proteinase, lipopolysac-charide (LPS) and so on. These virulent factors could escape the defense system in many ways to destroy periodontal supporting tissue. It is significant to investigate the pathogenesis of P. gingivalis in inducing inflammatory and immuno-logical reaction in periodontitis and determine the effective domain of P. gingivalis since it will provide the theoretical basis for immunotherapy in periodontitis.One of the pathological characters of adult periodontitis is the accumulation of leukocytes in gingival connective tissue. Leukocytes play an important role inthe process of periodontitis, and their activity is dependent on the contact and adhesion with cells and extracellular matrix mediated by a serial of adhesion molecules. At present, adhesion molecules are becoming the hot topic for their extensive functions. Intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 ( VCAM-1) are an adhesion molecule family expressing on the surfaces of many kinds of cells. They are important pro-inflammatory cy-tokines in inflammatory reaction and involved in the activation and accumulation of leukocytes. Interleukin 8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) are specific chemoattrctants for neutrophils and monocytes, respectively. Many studies showed that P. gingivalis affected the expression of ICAM-1, VCAM-1, IL-8 and MCP-1 in gingival tissue and they might play an important role in the pathogenesis of periodontitis. Vascular endothelial cells are important in the research of periodontitis since they are very sensitive to cytokines, LPS and bacteria. The interaction of vascular endothelial cells and periodontal pathogens is one of the major topics in periodontal research. However, a little information of the effects of P. gingivalis on the expression of ICAM-1, VCAM-1, IL-8 and MCP-1 was reported in China, even in the world. In the present experiment , we investigated the effects of P. gingivalis on the expression of ICAM-1, IL-8 and MCP-1 in human umbilical vein endothelial cells (HUVEC) , and analyzed the possible effective domain of P. gingivalis , compared the differential effect between P. gingivalis virulent strain W83 and invirulent strain ATCC33277. In addition, we investigated the expression of ICAM-1 and VCAM-1 in gingival samples of periodontitis patients in order to find out the possible pathogenesis of periodontitis induced by P. gingivalis .Methods1. Bacterial culture: P. gingivalis strains of W83 and ATCC33277 were grown in Brain Heart Infusion Broth, supplemented with yeast-extract (5 g/L) , Hemin (5mg/L), and Vitmin K3(1mg/L). The incubation was carried out inanaerobic bag at 35 C until at an optical density. Bacterial cells were washed twice with sterile phosphate buffered saline (PBS) by centrifiigation of 7000+ g for 10 min, and suspended in PBS at a concentration of 109 CFU/ml for use.2. Endothelial cell culture: Primary HUVEC were obtained from fresh human umbilical vein. The cells were collected after the treatment of 0.1% colla-genase and were incubated in collagen-coated 100-mm flasks with M199 medium supplemented with 30 mg/L of endothelial cell growth supplement and 20% fetal calf serum (FCS). HUVEC were maintained at 371 in a 5% CO2 atmosphe...
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