Effects of atorvastatin on the expression levels of tissue inhibitor of metalloproteinases timps/matrix metalloproteinases in bone tissues of femoral head necrosis induced by glucocorticoid

WANG Jian-zhong; WU Yong-gang; DONG Hui-zhen

doi:10.3969/j.issn.2095-252X.2014.11.015

Abstract：Objective To investigate the effects of atorvastatin on the mRNA expressions of matrix metalloproteinase-2 ( MMP-2 ), matrix metalloproteinase-9 ( MMP-9 ), tissue inhibitor of matrix metalloproteinases-1 ( TIMP-1 ) and tissue inhibitor of matrix metalloproteinases-2 ( TIMP-2 ) in bone tissues of the rats receiving glucocorticoid for a long time, and to discuss the effects and mechanism of atorvastatin in preventing glucocorticoid-induced femoral head necrosis ( FHN ).Methods A total of 30 healthy adult Sprague-Dawley ( SD ) rats were randomly divided into 3 groups, including glucocorticoid group, atorvastatin group and control group with 10 rats in each group. The rats in the glucocorticoid group and atorvastatin group were treated by intramuscular injection of 12.5 mg / kg prednisolone twice a week. The rats in the atorvastatin group were treated by intragastric administration with 1 mg / kg atorvastatin once a week. The maximum dose was 60 mg each day for experimental animals whose maximum weight was 60 kg. The rats in the control group were treated only by intramuscular injection of the same volume sodium chloride. After 4 weeks’ intervention, the parafifn-embedded osteonecrosis of the left femoral head was detected by HE stain, to identify osteoporosis and FHN. The total Ribonucleic Acid ( RNA ) of the right femoral head was extracted and the mRNA expression levels of MMP-2, MMP-9, TIMP-1 and TIMP-2 mRNAs were examined by reverse transcriptase polymerase chain reaction ( RT-PCR ).Results There was 1 death case in the glucocorticoid group and atorvastatin group respectively. The HE staining of bone tissue slices of the femoral head in the control group showed the bone trabecula was composed of lamellar bone and there were osteocytes in most of the lacunas of the trabecular bone and blood vessels and marrows between bone trabeculae. In the glucocorticoid group, the bony trabecula was sparse and there were a great number of discontinuous bone fragments and marrow necroses. Most of the osteocytes in the lacunas of bone fragments disappeared, with a lot of inlfammatory granulation tissues around. In the atorvastatin group, there was mild inlfammatory cell inifltration and thin bone trabecula. Osteocytes could be seen in most of the lacunas of the trabecular bone, and blood vessels and marrows between bone trabeculae. The expressions of MMP-2 in the glucocorticoid group, atorvastatin group and control group were 0.15±0.04, 0.10±0.09 and 0.09±0.03. The expressions of MMP-9 in 3 groups were 0.13±0.03, 0.11±0.05 and 0.08±0.02. The expressions of TIMP-1 in 3 groups were 0.07±0.02, 0.15±0.05 and 0.18±0.04. The expressions of TIMP-2 in 3 groups were 0.45±0.15, 0.73±0.08 and 0.69±0.19. The mRNA expressions of MMP-2 and MMP-9 in the glucocorticoid group were higher than that in the control group, and while the mRNA expressions of TIMP-1 and TIMP-2 were lower. The differences between them were statistically signiifcant (P<0.05 ). As to the comparison between the atorvastatin group and the control group, statistically signiifcant differences existed only in the expressions of MMP-9. The mRNA expressions of MMP-2 and MMP-9 in the atorvastatin group were lower than that in the control group, and while the mRNA expressions of TIMP-1 and TIMP-2 were higher. The differences between them were statistically signiifcant (P<0.05 ).Conclusions The mRNA expressions of MMP-2 and MMP-9 can be up-regulated and the expressions of TIMP-1 and TIMP-2 can be down-regulated by prednisolone, so as to improve the ratio between MMPs and TIMPs. The glucocorticoid control of MMPs / TIMPs can be antagonized by atorvastatin.