基于HIF-1α信号通路小鼠激素性股骨头坏死发病机理及补肾助阳中药干预机制研究

Femoral head necrosis (FHN) is a puzzle in the clinic of orthopedics. Excessive use of glucocorticoid is the most common cause of FHN. Ischemia and anoxia are the key links during the occurrence and development of FHN. Steroid induced avascular necrosis of femoral head (SANFH) has little self-repair capability and cannot completely repair the necrosis sites. Thus the progress of osteonecrosis will occur and finally induce the femoral head collapse. HIF-1α signaling pathway is the most characteristic hypoxia response pathway and has significant effect on the bone-tissue repair under hypoxia condition. It can modulate the coupling relationship between vascularization and bone-formation and improve the bone repair. Our preliminary study found that You-Gui-Yin can effectively prevent and cure SANFH with unclear mechanism of action. Accordingly, this study based on the tissue-specific HIF-1α gene-knockout mice model to establish the SANFH model to investigate the effect and mechanism of HIF-1α signaling pathway on SANFH and the effect link and action target of You-Gui-Yin for its prevention and curing activity on SANFH. Moreover, this study will further improve the TCM theory of "Kidney dominating bone". The conduct of this proposal has great theoretic significance and application value for the early diagnosis and treatment of SANFH and the improvement of TCM development.

股骨头坏死是骨科难题之一。糖皮质激素的大剂量应用是引起股骨头坏死的最常见因素。缺血/缺氧是激素性股骨头坏死发生发展的关键环节。激素性股骨头坏死自身修复能力有限，无法完全修复坏死灶，故会出现骨坏死的进展，最终导致股骨头塌陷。HIF-1α信号通路是最具特征性的低氧反应通路，在低氧状况下对骨组织修复有重要作用。它能调节血管形成和骨形成间的偶联关系，促进骨修复。课题组前期研究发现，补肾助阳方右归饮能有效防治激素性股骨头坏死，但其作用机制尚不清楚。鉴于此，本项目在建立组织特异性HIF-1α基因敲除小鼠模型的基础上，制备激素性股骨头坏死模型，研究HIF-1α信号通路对激素性股骨头坏死的作用及其机制，并从HIF-1α信号转导的角度研究右归饮防治激素性股骨头坏死的效应环节和作用靶点，进一步丰富"肾主骨"理论。本课题的实施对激素性股骨头坏死的早期诊断和治疗以及促进中医药的发展具有重大的理论意义和应用价值。

股骨头坏死是骨科难题之一。糖皮质激素的大剂量应用是引起股骨头坏死的最常见因素。缺血/缺氧是激素性股骨头坏死发生发展的关键环节。激素性股骨头坏死自身修复能力有限，无法完全修复坏死灶，故会出现骨坏死的进展，最终导致股骨头塌陷。HIF-1α信号通路是最具特征性的低氧反应通路，在低氧状况下对骨组织修复有重要作用。它能调节血管形成和骨形成间的偶联关系，促进骨修复。课题组前期研究发现，补肾助阳方右归饮能有效防治激素性股骨头坏死（SINFH），但其作用机制尚不清楚。鉴于此，本项目首先在建立制备SINFH模型的基础上，通过各种分子生物学手段检测，发现长时间造模使皮质变薄,骨小梁稀疏、变细、萎缩，骨髓腔扩大，正常骨组织常被脂肪组织代替,造血细胞明显减少,股骨头软骨下区骨细胞核边聚、固缩、核深染，有些核消失而使骨陷窝空虚增加。右归饮处理改善上述骨组织变化。另外，HIF信号在SINFH造模过程成骨细胞中出现先升高后下降的趋势，右归饮处理明显提高和延长HIF-1α的表达水平。为进一步明确HIF在SINFH中的作用，通过获得成骨特异性HIF-1α基因敲除小鼠（Col1a-Cre，HifFlox/Flox）的基础上，进行SINFH造模，结果表明SINFH组出现更加严重的骨量缺失，骨小梁稀疏情况更加严重，而右归饮处理干预改善作用不如正常C57小鼠显著。上述结果表明HIF-1α信号通路对激素性股骨头坏死修复中有重要作用，右归饮干预可通过调控HIF信号通路的表达，进而改善激素性股骨头坏死。本课题研究进一步丰富“肾主骨”理论，也对激素性股骨头坏死的早期诊断和治疗以及促进中医药的发展具有重大的理论意义和应用价值。