Effects of micro-amounts of Porphyromonas gingivalis lipopolysaccharide on rabbit inflammatory immune response and development of atherosclerosis.

BACKGROUND AND OBJECTIVE: Porphyromonas gingivalis (Pg) lipopolysaccharide is associated with the immune response and atherosclerosis. This study aimed to evaluate the effects of micro-amounts of Pg-lipopolysaccharide on rabbit inflammatory immune response and the development of atherosclerosis. MATERIAL AND METHODS: Twenty-four New Zealand white rabbits were randomly divided into four groups (n = 6). Group A was fed a regular diet and normal saline. Group B was supplied with a high-fat diet and normal saline. Group C was treated with a normal diet and Pg-lipopolysaccharide. Group D was given a high-fat diet and Pg-lipopolysaccharide. After 14 wk, the rabbits were killed to determine the changes in pathological indices. RESULTS: The serum lipid levels of groups B and D were significantly higher than that of group A (p < 0.01), and that of group C was higher (p < 0.05). Serum interleukin-6, monocyte chemoattractant protein-1 and tumor necrosis factor-α levels were significantly elevated by individual high-fat diets or Pg-lipopolysaccharide stimulation (p < 0.05). Groups A and C did not undergo evident aortic pathological damages, while foam cells appeared in the other two groups. Real-time polymerase chain reaction detection showed that toll-like receptor-2, interleukin-6, matrix metalloproteinase-9 and monocyte chemoattractant protein-1 were highly expressed in groups B and D (p < 0.05), and toll-like receptor-4, C-reactive protein and tumor necrosis factor-α levels were higher than those of group A (p < 0.05). Western blotting showed that transcription factor NF-κB p65 was expressed more highly in the three experimental groups than in group A (t = 9.26, p < 0.01). CONCLUSION: Micro-amounts of Pg-lipopolysaccharide induced the high expressions of inflammatory factors and mediated the inflammatory response. Pg-lipopolysaccharide elevated the blood lipid level less significantly than the high-fat diet did, but it may promote atherosclerosis.