Appleton C T G, Pitelka V, Henry J, Beier F
Canadian Institutes of Health Research, Ottawa, Ontario, Canada.
Arthritis Rheum. 2007 Jun;56(6):1854-68. doi: 10.1002/art.22711.
To analyze genome-wide changes in chondrocyte gene expression in a surgically induced model of early osteoarthritis (OA) in rats, to assess the similarity of this model to human OA, and to identify genes and mechanisms leading to OA pathogenesis.
OA was surgically induced in 5 rats by anterior cruciate ligament transection and partial medial meniscectomy. Sham surgery was performed in 5 additional animals, which were used as controls. Both groups underwent 4 weeks of forced mobilization, 3 times per week. RNA was extracted directly from articular chondrocytes in the OA (operated), contralateral, and sham-operated knees. Affymetrix GeneChip expression arrays were used to assess genome-wide changes in gene expression. Expression patterns of selected dysregulated genes, including Col2a1, Mmp13, Adamts5, Ctsc, Ptges, and Cxcr4, were validated by real-time polymerase chain reaction, immunofluorescence, or immunohistochemistry 2, 4, and 8 weeks after surgery.
After normalization, comparison of OA and sham-operated samples showed 1,619 differentially expressed probe sets with changes in their levels of expression > or = 1.5-fold, 722 with changes > or = 2-fold, 135 with changes > or = 4-fold, and 20 with changes of 8-fold. Dysregulated genes known to be involved in human OA included Mmp13, Adamts5, and Ptgs2, among others. Several dysregulated genes (e.g., Reln, Phex, and Ltbp2) had been identified in our earlier microarray study of hypertrophic chondrocyte differentiation. Other genes involved in cytokine and chemokine signaling, including Cxcr4 and Ccl2, were identified. Changes in gene expression were also observed in the contralateral knee, validating the sham operation as the appropriate control.
Our results demonstrate that the animal model mimics gene expression changes seen in human OA, supporting the relevance of newly identified genes and pathways to early human OA. We propose new avenues for OA pathogenesis research and potential targets for novel OA treatments, including cathepsins and cytokine, chemokine, and growth factor signaling pathways, in addition to factors controlling the progression of chondrocyte differentiation.
分析大鼠手术诱导的早期骨关节炎（OA）模型中软骨细胞基因表达的全基因组变化，评估该模型与人类OA的相似性，并确定导致OA发病机制的基因和机制。
通过切断前交叉韧带和部分内侧半月板切除术，对5只大鼠进行手术诱导OA。另外5只动物进行假手术，作为对照。两组动物均每周进行3次，共4周的强迫活动。直接从OA（手术）、对侧和假手术膝关节的关节软骨细胞中提取RNA。使用Affymetrix GeneChip表达阵列评估基因表达的全基因组变化。通过实时聚合酶链反应、免疫荧光或免疫组织化学在术后2、4和8周对选定的失调基因（包括Col2a1、Mmp13、Adamts5、Ctsc、Ptges和Cxcr4）的表达模式进行验证。
标准化后，OA样本与假手术样本的比较显示，有1619个差异表达的探针集，其表达水平变化≥1.5倍，722个变化≥2倍，135个变化≥4倍，20个变化≥8倍。已知参与人类OA的失调基因包括Mmp13、Adamts5和Ptgs2等。在我们早期关于肥大软骨细胞分化的微阵列研究中，已经鉴定出几个失调基因（如Reln、Phex和Ltbp2）。还鉴定了其他参与细胞因子和趋化因子信号传导的基因，包括Cxcr4和Ccl2。在对侧膝关节也观察到基因表达的变化，证实假手术是合适的对照。
我们的结果表明，该动物模型模拟了人类OA中观察到的基因表达变化，支持新鉴定的基因和途径与早期人类OA的相关性。我们提出了OA发病机制研究的新途径和新型OA治疗的潜在靶点，除了控制软骨细胞分化进程的因素外，还包括组织蛋白酶以及细胞因子、趋化因子和生长因子信号通路。
