Relationship between Lp-PLA_2 and vulnerable atherosclerotic plaque in rabbits / 中国病理生理杂志

ABSTRACT

AIM: To explore the expressive role of lipoprotein-associated phospholipase A_2, high sensitive C-reactive protein and matrix metalloproteinase-9 in vulnerable atherosclerotic plaques in a rabbit model. METHODS: Forty eight New Zealand white male rabbits were randomly divided into 4 groups (12 rabbits each) control group, stable plaque group, p53 group, and p53+drug group. Rabbits in control group were fed with a regular diet and underwent sham operation. Rabbits in stable plaque group, p53 group and p53+drug group underwent balloon induced arterial wall injury and then were fed on a diet with 1% cholesterol. The animals were all fed for 3 months, then the rabbits in p53 group and p53+drug group underwent Ad5-CMV p53 transfection at 10th week. Before killed, the animals in p53+drug group underwent pharmacological triggering with Russell's viper venom (RVV) and histamine to induce the rupture of the atherosclerotic plaques. At the 1st day and before sacrifice, the serum was collected for measuring Lp-PLA_2, hs-CRP, MMP-9, HDL, LDL and VLDL. The expressions of Lp-PLA_2, hs-CRP and MMP-9 in tissues were determined by the methods of hybridization and immunohistochemistry. RESULTS: At the end of 12th week, the serum and tissue levels of Lp-PLA_2 and MMP-9 in stable plaque group, p53 group and p53+drug group were significant different from those in control group and in each group at the first day (P<0.05). The serum levels of Lp-PLA_2 and hs-CRP in p53 group and p53+drug group were significantly higher than those in control group and stable group (P<0.05). The serum levels of Lp-PLA_2, hs-CRP and MMP-9 were all significantly different between p53 group and p53+drug group (P<0.05). At the end of 12th week, pathological results showed that 4 groups were normal artery, stable plaque, vulnerable plaque and rupture plaque, respectively. The fabric cap was thicker in plaque groups than that in normal group (P<0.05). The rupture and formation of thrombus were more significant in p53+drug group than those in p53 group. The serum level of Lp-PLA_2 had negative interrelated relationship with fabric cap in plaque groups (r=-0.710, P<0.01), and hs-CRP, MMP-9 had no interrelated relationships with fabric cap in plaque groups. CONCLUSION: Base on the successful establishment of the atherosclerotic plaque animal model, serum Lp-PLA_2 shows better interrelated relationships to plaques stability. Combination with hs-CRP and MMP-9, we can exactly evaluate the nature of plaques.