目的：研究牙龈卟啉单胞菌和尼古丁影响动脉粥样硬化的初步分子机制。方法：在单核细胞U937细胞中，用CCK-8法检测尼古丁、牙龈卟啉单胞菌脂多糖（Porphyromonas gingivalis lipopolysaccharide，P.g-LPS）及二者联合对U937细胞增殖能力的影响；实时定量荧光聚合酶链反应（Real-time PCR）检测尼古丁对P.g-LPS诱导炎症因子白细胞介素（interleukin, IL）-6能力的影响。在血管内皮细胞中，用Real-time PCR和蛋白印记杂交实验检测尼古丁、P.g-LPS及二者联合应用对单核细胞趋化因子（C-C模体） 配体8 ［chemokine (C-C motif) ligand 8, CCL-8］和血管细胞黏附因子1（vascular cell adhesion molecule 1，Vcam-1）、非常晚期抗原4α（very late antigen 4 alpha，VLA4α）、肿瘤坏死因子受体超家族成员4（tumor necrosis factor receptor superfamily member 4，OX40）和其配体（OX40 ligand，OX40L）的表达的影响。同时，在尼古丁和P.g-LPS共同作用下，用黏附实验检测单核细胞与血管内皮细胞的黏附能力。结果：P.g-LPS并不影响尼古丁促进单核细胞系U937增殖的作用，100 μmol/L尼古丁能抑制P.g-LPS诱导U937细胞产生IL-6的能力。在血管内皮细胞中，与对照和单一药物处理相比，尼古丁和P.g-LPS共同作用可以促进其表达CCL-8及Vcam-1、VLA4α、OX40和OX40L。黏附实验结果显示，尼古丁和P.g-LPS共同刺激可以明显提高单核细胞黏附血管内皮细胞的能力。结论：牙龈卟啉单胞菌和尼古丁可能通过上调CCL-8表达募集单核细胞到血管内皮损伤处，并通过增强黏附分子Vcam1/VLA4α及OX40L/OX40的相互作用，促进单核细胞与血管内皮细胞黏附，参与动脉粥样硬化病损的启动和形成。

Objective： To investigate molecular mechanism involved in nicotine in combination with Porphyromonas gingivalis (P.g) caused monocyte-endothelial cell adhesion. Methods: The effect of nicotine, P.g-lipopolysaccharide (P.g-LPS) and their combination on the proliferation of U937 cells was determined by CCK-8 method. Interleukin-6 (IL-6) expression was investigated by Real-time PCR after U937 cells were treated with nicotine, P.g-LPS and their combination. In human umbilical vein endothelial cells (HUVECs), the expressions of monocyte chemoattractant protein CCL-8 and adhesion molecules including vascular cell adhesion molecule 1 (Vcam-1), very late antigen 4 alpha (VLA4α), tumor necrosis factor receptor superfamily member 4 (OX40) and OX40 ligand (OX40L) were detected by Real-time PCR or Western blotting assays after HUVEC cells were treated with nicotine, P.g-LPS and their combination. Adhesion of monocytes to endothelial cells was detected after the HUVECs and U937 cells were stimulated with nicotine, P.g-LPS and their combination, respectively. Results: P.g-LPS did not affect the proliferative ability of nicotine in U937 cells. However, the ability of P.g-LPS induced IL-6 expression was inhibited by 100 μmol/L nicotine in U937 cells. In HUVECs, the expressions of CCL-8, Vcam-1, VLA4α, OX40 and OX40L were significantly up-regulated by nicotine and P.gLPS combination compared with nicotine alone, P.g-LPS alone and the untreated control. Adhesion of monocytes to HUVECs results showed that the two types of cells treated with nicotine in combination with P.g-LPS could markedly increase the adhesion ability of monocytes to HUVECs. Conclusion: P.g-LPS in combination with nicotine could recruit monocytes to endothelial lesion through up-regulation of CCL-8, and promote adhesion of monocytes to endothelial cells through enhancement of Vcam-1/VLA4α and OX40/OX40L interactions, which could be involved in the initiation and development of atherosclerosis.