Effect of Porphyromonas gingivalis lipopolysaccharide on theregulation of OPG/RANKL and Interleukin-6 in the serum ofsimulating murine model of postmenopausal osteoporosis

• Main Authors: Kuei-Chih Yeh, 葉桂枝
• Other Authors: Hsein-Kun Lu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/94131325892074017877

碩士 === 臺北醫學大學 === 牙醫學系 === 93 === Periodontitis is a chronic inflammatory disease which results in the breakdown of tooth supporting structures, especially alveolar bone destruction. Deep periodontal pocket, attachment level loss, and alveolar bone loss are found under clinical examination. Porphyromonas gingivalis (P. gingivalis), a black-pigmented gram-negative anaerobic bacterial rods, is a vital pathogen for adult periodontitis. P. gingivalis has been proved to contribute to bone resorption in many vivo studies. However, unlike the clear relationship between osteoporosis and tooth loss, controversy still exists concerning the association between osteopenia/opteoporosis and the periodontal pathogen. The purpose of the present study is to clarify the etiologic relationship of P. gingivalis lipopolysaccharide (P. gingivalis LPS) and the expression of OPG, RANKL, IL-6 in the serum of postmenopausal osteoporosis mice. Injection of Escherichia coli LPS (E. coli LPS) was need as the control. Ninty 10-week old ICR female mice were divided into ovariectomized group (experimental group) and sham-operation group (control group). After operation 4 weeks, we collect the serum as baseline. 100 µg P. gingivalis LPS and E. coli LPS were separately injected into the peritoneum of experimental group (30 mice) and control group (30 mice). Subsequently, we collected the serum 1,3,6,24 and 48 hours after the injection of both LPS. Then the concentrations of IL-6, OPG and RANKL of serum will be estimated by using sandwich ELISA. The femur bone was dissected for TRAP stain analysis. Besides, 4 weeks after operation, 15 experimental mice and 15 control mice was sacrificed for TRAP stain to compare lipopolysaccharide effect. Mann-Whitney U test was applied to study the difference of OPG, RANKL, OPG/RANKL ratio, IL-6 between P. gingivalis LPS and E. coli LPS. Wilcoxon signed rank test was used to study the difference of OPG, RANKL, OPG/RANKL ratio, IL-6 between each time interval and baseline in group. The strength of correlations between IL-6 and OPG, RANKL, OPG/RANKL ratio at each time interval in group were determined by Spearman rank correlation coefficients. The difference of TRAP positive cell count in the specimen among was compared by using Kruskal-Wallis test. Results with p< 0.05 were defined statistically different. In the injection of P. gingivalis LPS of experimental and control group, OPG/RANKL ratio decreased at 3 hours (p< 0.05), then trended to rising tendency. IL-6 rose at 1、3 hours (p< 0.05). Besides, the changes of OPG, RANKL, OPG/RANKL ratio, IL-6 were greater in injection of E. coli LPS than P. gingivalis LPS. There is stronger TRAP positive cells distribution in experimental group than control group (p< 0.05). No matter single booster of P. gingivalis LPS or E. coli LPS did not effect the expression of TRAP positive cells. It should be noticed that only single shot of bacterial LPS was applied in this animal model. P. gingivalis LPS directly effected the expression of IL-6, but not OPG/RANKL system. It indicated that OPG/RANKL ratio of experimental group injected with P. gingivalis LPS might also be regulated by a more complex system. Removal of ovary did not effect the expression of IL-6; our data also indicated there were no correlation of IL-6, expression of OPG, RANKL, and OPG/RANKL ratio. In addition, the stimulatory effect of E. coli LPS was stronger than P. gingivalis LPS.