Yatabe T, Mochizuki S, Takizawa M, Chijiiwa M, Okada A, Kimura T, Fujita Y, Matsumoto H, Toyama Y, Okada Y
Department of Pathology, Keio University, Tokyo, Japan.
Ann Rheum Dis. 2009 Jun;68(6):1051-8. doi: 10.1136/ard.2007.086884. Epub 2008 Jul 28.
Intra-articular injection of hyaluronan (HA) has been suggested to have a disease-modifying effect in osteoarthritis, but little is known about the possible mechanisms.
To investigate the effects of HA species of different molecular mass, including 800 kDa (HA800) and 2700 kDa (HA2700), on the expression of aggrecanases (ie, ADAMTS species), which play a key role in aggrecan degradation.
The effects of HA species on the expression of ADAMTS1, 4, 5, 8, 9 and 15 in interleukin 1alpha (IL1alpha)-stimulated osteoarthritic chondrocytes were studied by reverse transcription PCR and real-time PCR. Expression of ADAMTS4 protein and aggrecanase activity and signal transduction pathways of IL1, CD44 and intracellular adhesion molecule 1 (ICAM1) were examined by immunoblotting.
IL1alpha treatment of chondrocytes induced ADAMTS4, and HA800 and HA2700 significantly decreased IL1alpha-induced expression of ADAMTS4 mRNA and protein. IL1alpha-stimulated aggrecanase activity in osteoarthritic chondrocytes was reduced by treatment with HA2700 or transfection of small interfering RNA for ADAMTS4. A similar result was obtained when HA2700 was added to explant cultures of osteoarthritic cartilage. HA2700 neither directly inhibited nor bound to ADAMTS4. Downregulation of ADAMTS4 expression by HA2700 was attenuated by treatment of IL1alpha-treated chondrocytes with antibodies to CD44 and/or ICAM1. The increased phosphorylation of IL1 receptor-associated kinase-1 and extracellular signal-regulated protein kinase1/2 induced by the IL1alpha treatment was downregulated by enhanced IRAK-M expression after HA2700 treatment.
These data suggest that HA2700 suppresses aggrecan degradation by downregulating IL1alpha-induced ADAMTS4 expression through the CD44 and ICAM1 signalling pathways in osteoarthritic chondrocytes.
关节腔内注射透明质酸（HA）被认为对骨关节炎具有病情改善作用，但对其可能的作用机制知之甚少。
研究不同分子量的HA，包括800 kDa（HA800）和2700 kDa（HA2700），对聚糖酶（即ADAMTS家族）表达的影响，聚糖酶在蛋白聚糖降解中起关键作用。
通过逆转录PCR和实时PCR研究HA对白细胞介素1α（IL1α）刺激的骨关节炎软骨细胞中ADAMTS1、4、5、8、9和15表达的影响。通过免疫印迹检测ADAMTS4蛋白的表达、聚糖酶活性以及IL1、CD44和细胞间黏附分子1（ICAM1）的信号转导途径。
IL1α处理软骨细胞可诱导ADAMTS4表达，而HA800和HA2700可显著降低IL1α诱导的ADAMTS4 mRNA和蛋白表达。用HA2700处理或转染针对ADAMTS4的小干扰RNA可降低IL1α刺激的骨关节炎软骨细胞中的聚糖酶活性。将HA加入骨关节炎软骨外植体培养物中也得到了类似结果。HA2700既不直接抑制ADAMTS4，也不与ADAMTS4结合。用抗CD44和/或ICAM1抗体处理IL1α处理的软骨细胞可减弱HA2700对ADAMTS4表达的下调作用。HA2700处理后，IRAK-M表达增强，可下调IL1α处理诱导的IL1受体相关激酶-1和细胞外信号调节蛋白激酶1/2的磷酸化增加。
这些数据表明，HA2700通过骨关节炎软骨细胞中的CD44和ICAM1信号通路下调IL1α诱导的ADAMTS4表达，从而抑制蛋白聚糖降解。
