Nishida Y, D'Souza A L, Thonar E J, Knudson W
Rush Medical College, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA.
Arthritis Rheum. 2000 Jun;43(6):1315-26. doi: 10.1002/1529-0131(200006)43:6<1315::AID-ANR14>3.0.CO;2-#.
To determine the effects of interleukin-1alpha (IL-1alpha) on the expression of hyaluronan synthase (HAS), CD44, and aggrecan in human articular chondrocytes, and to assess the net result of these metabolic changes on the accumulation of hyaluronan within articular cartilage.
Normal human articular cartilage slices, as well as isolated chondrocytes, were treated with IL-1alpha. Changes in the relative expression of messenger RNA (mRNA) for HAS-2, CD44, and aggrecan were determined by competitive, quantitative reverse transcriptase-polymerase chain reaction. Hyaluronan accumulation was characterized by staining with a hyaluronan-specific binding protein and by fluorophore-assisted carbohydrate electrophoresis, while proteoglycan content was determined by alcian blue and Safranin O staining, CD44 protein expression by immunohistochemistry, and aggrecan biosynthesis by 35S-sulfate incorporation. Changes in cell-associated matrix sizes were visualized by a particle exclusion assay.
IL-1alpha stimulated the expression of HAS-2 and CD44 mRNA (3.5-fold and 3-fold, respectively), but inhibited the expression of aggrecan mRNA. In IL-1-treated chondrocytes, extracellular hyaluronan decreased, while intracellular accumulation of hyaluronan was enhanced. Together with the decrease in expression of aggrecan, a dramatic reduction in cell-associated matrix was observed. IL-1-treated cartilage slices displayed a prominent depletion of aggrecan as well as hyaluronan within the upper layers of the tissue. The regional loss of hyaluronan coincided with a regional up-regulation of CD44.
These data demonstrate that IL-1alpha stimulates HAS-2 at the same time as it inhibits the expression of aggrecan. Although hyaluronan biosynthesis is up-regulated, so too is the expression of CD44 and the internalization/catabolism of hyaluronan. The net result is a loss of hyaluronan in areas of the articular cartilage where increases in CD44 expression are most prominent. This depletion of hyaluronan in the upper layers of the tissue likely facilitates the prominent loss of aggrecan from the tissue.
确定白细胞介素-1α（IL-1α）对人关节软骨细胞中透明质酸合酶（HAS）、CD44和聚集蛋白聚糖表达的影响，并评估这些代谢变化对关节软骨内透明质酸积累的最终结果。
用IL-1α处理正常人关节软骨切片以及分离的软骨细胞。通过竞争性定量逆转录-聚合酶链反应测定HAS-2、CD44和聚集蛋白聚糖信使核糖核酸（mRNA）的相对表达变化。通过用透明质酸特异性结合蛋白染色和荧光辅助碳水化合物电泳来表征透明质酸积累，而蛋白聚糖含量通过阿尔新蓝和番红O染色测定，CD44蛋白表达通过免疫组织化学测定，聚集蛋白聚糖生物合成通过35S-硫酸盐掺入测定。通过颗粒排除试验观察细胞相关基质大小的变化。
IL-1α刺激HAS-2和CD44 mRNA的表达（分别为3.5倍和3倍），但抑制聚集蛋白聚糖mRNA的表达。在IL-1处理的软骨细胞中，细胞外透明质酸减少，而细胞内透明质酸积累增强。随着聚集蛋白聚糖表达的降低，观察到细胞相关基质显著减少。IL-1处理的软骨切片在组织上层显示出聚集蛋白聚糖以及透明质酸的显著消耗。透明质酸的区域损失与CD44的区域上调一致。
这些数据表明，IL-1α在抑制聚集蛋白聚糖表达的同时刺激HAS-2。尽管透明质酸生物合成上调，但CD44的表达以及透明质酸的内化/分解代谢也上调。最终结果是在关节软骨中CD44表达增加最显著的区域透明质酸丢失。组织上层透明质酸的这种消耗可能促进了组织中聚集蛋白聚糖的显著丢失。
