Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland, United States of America.
PLoS One. 2010 Dec 29;5(12):e15174. doi: 10.1371/journal.pone.0015174.
Excessive mechanical loading of articular cartilage producing hydrostatic stress, tensile strain and fluid flow leads to irreversible cartilage erosion and osteoarthritic (OA) disease. Since application of high fluid shear to chondrocytes recapitulates some of the earmarks of OA, we aimed to screen the gene expression profiles of shear-activated chondrocytes and assess potential similarities with OA chondrocytes.
METHODOLOGY/PRINCIPAL FINDINGS: Using a cDNA microarray technology, we screened the differentially-regulated genes in human T/C-28a2 chondrocytes subjected to high fluid shear (20 dyn/cm(2)) for 48 h and 72 h relative to static controls. Confirmation of the expression patterns of select genes was obtained by qRT-PCR. Using significance analysis of microarrays with a 5% false discovery rate, 71 and 60 non-redundant transcripts were identified to be ≥2-fold up-regulated and ≤0.6-fold down-regulated, respectively, in sheared chondrocytes. Published data sets indicate that 42 of these genes, which are related to extracellular matrix/degradation, cell proliferation/differentiation, inflammation and cell survival/death, are differentially-regulated in OA chondrocytes. In view of the pivotal role of cyclooxygenase-2 (COX-2) in the pathogenesis and/or progression of OA in vivo and regulation of shear-induced inflammation and apoptosis in vitro, we identified a collection of genes that are either up- or down-regulated by shear-induced COX-2. COX-2 and L-prostaglandin D synthase (L-PGDS) induce reactive oxygen species production, and negatively regulate genes of the histone and cell cycle families, which may play a critical role in chondrocyte death.
CONCLUSIONS/SIGNIFICANCE: Prolonged application of high fluid shear stress to chondrocytes recapitulates gene expression profiles associated with osteoarthritis. Our data suggest a potential link between exposure of chondrocytes/cartilage to abnormal mechanical loading and the pathogenesis/progression of OA.
关节软骨承受过度的机械负荷，产生静水压力、拉伸应变和流体流动，导致不可逆的软骨侵蚀和骨关节炎（OA）疾病。由于向软骨细胞施加高流体剪切力可以再现 OA 的一些特征，我们旨在筛选剪切激活的软骨细胞的基因表达谱，并评估其与 OA 软骨细胞的潜在相似性。
方法/主要发现：使用 cDNA 微阵列技术，我们筛选了在高流体剪切力（20 dyn/cm(2)）下培养 48 小时和 72 小时的人 T/C-28a2 软骨细胞相对于静态对照的差异调节基因。通过 qRT-PCR 获得了选择基因表达模式的确认。使用假发现率为 5%的微阵列显著性分析，鉴定出 71 个和 60 个非冗余转录物分别上调 2 倍以上和下调 0.6 倍以下。已发表的数据表明，这些基因中有 42 个与细胞外基质/降解、细胞增殖/分化、炎症和细胞存活/死亡有关，在 OA 软骨细胞中存在差异调节。鉴于环氧化酶-2（COX-2）在体内 OA 的发病机制和/或进展以及体外剪切诱导的炎症和凋亡中的关键作用，我们鉴定了一组由剪切诱导的 COX-2 上调或下调的基因。COX-2 和 L-前列腺素 D 合酶（L-PGDS）诱导活性氧的产生，并负调控组蛋白和细胞周期家族的基因，这可能在软骨细胞死亡中起关键作用。
结论/意义：长时间施加高流体剪切力到软骨细胞可以再现与骨关节炎相关的基因表达谱。我们的数据表明，软骨细胞/软骨暴露于异常机械负荷与 OA 的发病机制/进展之间存在潜在联系。
