FGF18对兔椎间盘退变抗分解代谢作用及调节机制

Anti- catabolism Effect of FGF- 18 on Rabbit Intervertebral Disc Degeneration and Regulating Mechanism

目的 探讨纤维母细胞生长因子18（FGF-18）在兔椎间盘退变（intervertebral disc degeneration,IDD）发生过程中抗分解代谢作用及对凋亡的抑制作用.方法 取新西兰大白兔45只,体重为2.5~3.0kg.随机分为3组,每组15只,行纤维环穿刺造模（分别在L3~L4、L4~L5及L5~L6椎间盘进行穿刺）,造模后予椎间盘内注射阳性过表达FGF18慢病毒（干预组）、阴性慢病毒（模型组）,假手术组仅暴露椎间盘不做针刺处理.术后4周、8周将各组大白兔处死取材,分离椎间盘.实时荧光定量PCR和蛋白印记检测细胞外基质降解酶MMP-3、ADAMTS-5表达变化.HE染色及组织学评分评估椎间盘退变情况.免疫组化法检测caspase-3的表达并经统计学分析.TUNEL法检测各时间点髓核细胞凋亡率.结果 术后8周时,各手术组的MMP-3、ADAMTS-5表达均高于假手术组,干预组表达低于模型组.组织学提示FGF18处理延缓椎间盘退变.免疫组化结果显示各手术组caspase-3阳性表达髓核细胞均较假手术组明显增多,干预组较模型组下调.定量分析TUNEL染色显示干预组凋亡髓核细胞较模型组亦减少.结论 髓核细胞过表达纤维母细胞生长因子18可抑制细胞凋亡,进而延缓椎间盘退变进程.

Objective To investigate the anti-catabolism and anti-apoptosis effects of fibroblast growth factor 18 （FGF-18） in the process of rabbit intervertebral disc degeneration （IDD）. Methods A total of 45 New Zealand white rabbits, weighed 2.5-3.0 kg, were randomly divided into 3 groups and each group has 15. Annulus fibmsus puncture was modeled in 2 groups（puncturing L3-L4, L4-L5 and L5-L6 intervertebral disc）. After modeled, the disc were injected with overexpression FGF18 lentivirus （intervention group） or negative lentivirus（model group）. The disc was was only exposed and not punctured in the sham group. Each group of rabbits were sacrificed at 4 and 8 weeks after surgery, subsequently the discs were harvested. Real-time PCR and Western blot analysis were used to detect the expression of extracellular matrix-degrading enzyme MMP-3 and ADAMTS-5. We also evaluated disc degeneration using HE staining and histological grading system. The expression of caspase-3 in intervertebral disc tissue was observed using immunohistochemical study. TUNEL stain was performed to detect apoptosis rate in each stage of disc nucleus pulposus cells. Results The expression of MMP-3 and ADAMTS-5 in operated groups were higher than sham-operated group at 8 weeks after operation. FGF-18 treatment inhibited the expression at both mRNA and protein level. Histologic examination showed disc degeneration was delayed when treated with FGF18. Immunohistochemical results showed caspase-3 positive nucleus pulposus cells were marked increased in operated groups, and the intervention group was lower than the model group. Quantification of TUNEL staining also showed that the intervention group had fewer apoptotic nucleus pulposus cells than the model group. Conclusion Our findings indicate that FGF-18 overexpression in rabbit intervertebral disc cells is effective in preventing apoptotic cell death, thus regulating intervertebral disc degeneration.