The effects of high magnitude cyclic tensile load on cartilage matrix metabolism in cultured chondrocytes
The effects of high magnitude cyclic tensile load on cartilage matrix metabolism in cultured chondrocytes
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DOI：
10.1078/0171-9335-00089
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发表时间：
2000-09-01
影响因子：
6.6
通讯作者：
Tanne, K
中科院分区：
文献类型：
--
作者：
Honda, K;Ohno, S;Tanne, K
过度的机械负荷被认为是骨关节病（OA）发病的原因，但机械负荷引起软骨破坏的机制尚不清楚。在这项研究中，我们使用Flexercell应变单元对培养的软骨细胞施加高幅度的循环拉伸载荷，其产生细胞形态从多边形到纺锤形的变化，并检查软骨基质的蛋白水平和基质金属蛋白酶（MMPs）、基质金属蛋白酶组织抑制剂（TIMPs）和促炎细胞因子（如IL-1 β和TNF-α）的基因表达。甲苯胺蓝染色，II型胶原免疫染色，和[S-35]硫酸盐掺入蛋白多糖的测定显示软骨细胞培养物中软骨特异性基质的水平降低，受到高幅度的循环拉伸负荷。PCR-Southern杂交结果显示，高强度的周期性拉伸载荷可使培养的软骨细胞中MMP-1、MMP-3、MMP-9、IL-1 β、TNF-α和TIMP-1的mRNA水平升高，而MMP-2和TIMP-2的mRNA水平无明显变化。此外，诱导MMP-1，MMP-3和MMP-9的mRNA表达观察到放线菌酮，蛋白质合成的抑制剂的存在下。这些结果表明，过度的机械负荷直接改变软骨的代谢，减少基质成分，并导致MMPs和TIMPs之间的定量失衡。
Excessive mechanical load is thought to be responsible for the onset of osteoarthrosis (OA), but the mechanisms of cartilage destruction caused by mechanical loads remain unknown. In this study we applied a high magnitude cyclic tensile load to cultured chondrocytes using a Flexercell strain unit, which produces a change in cell morphology from a polygonal to spindle-like shape, and examined the protein level of cartilage matrixes and the gene expression of matrix metalloproteinases (MMPs), tissue inhibitors of matrix metalloproteinases (TIMPs) and proinflammatory cytokines such as IL-1 beta and TNF-alpha. Toluidine blue staining, type II collagen immunostaining, and an assay of the incorporation of [S-35]sulfate into proteoglycans revealed a decrease in the level of cartilage-specific matrixes in chondrocyte cultures subjected to high magnitude cyclic tensile load. PCR-Southern blot analysis showed that the high magnitude cyclic tensile load increased the mRNA level of MMP-1, MMP-3, MMP-9, IL-1 beta, TNF-alpha and TIMP-1 in the cultured chondrocytes, while the mRNA level of MMP-2 and TIMP-2 was unchanged. Moreover, the induction of MMP-1, MMP-3 and MMP-9 mRNA expression was observed in the presence of cycloheximide, an inhibitor of protein synthesis. These findings suggest that excessive mechanical load directly changes the metabolism of cartilage by reducing the matrix components and causing a quantitative imbalance between MMPs and TIMPs.