Chubinskaya S, Huch K, Mikecz K, Cs-Szabo G, Hasty K A, Kuettner K E, Cole A A
Department of Biochemistry, Rush Medical College, Chicago, Illinois 60612, USA.
Lab Invest. 1996 Jan;74(1):232-40.
The loss of aggrecan from articular cartilage may lead to the development of osteoarthritis (OA). Degradation products of human aggrecan, generated in vivo by enzymatic cleavages, have been identified in synovial fluid of patients with rheumatoid arthritis and OA. One matrix metalloproteinase (MMP), stromelysin (MMP-3), and an unidentified proteinase called "aggrecanase" are believed to generate these products in pathologic conditions. Thus far, only one proteinase, neutrophil collagenase (MMP-8), has been shown in vitro to be capable of cleavage of the aggrecan molecule at the "aggrecanase" site. In this study, we compare the presence and distribution of MMP-3 and MMP-8 in cartilages from two different joints of normal human donors. We determined whether mRNA for MMP-8 is expressed in normal human articular cartilage from different joints. In addition, we compared differences in MMP-8 and MMP-3 gene expression between human ankle and knee cartilage after in vitro stimulation by interleukin (IL)-1 beta. These two joints were chosen because the incidence of symptomatic and radiographic OA varies between the different joints. The knee is the most frequently involved joint, whereas the ankle (talocrural) joint is relatively rarely affected. Message for MMP-8 was detected in untreated cartilage from normal knee joints, but not in untreated cartilage of normal ankle joints. Message for MMP-3 was detectable in most of the knee and ankle cartilages. Messenger RNA expression for both MMPs could be up-regulated by IL-1 beta. The highest doses of IL-1 beta appeared to be most effective in stimulation of mRNA for MMP-3, whereas MMP-8 expression was more sensitive to lower doses of IL-1 beta. The fact that ankle cartilage with a low incidence of OA does not express MMP-8, whereas knee cartilage with a high incidence of OA does not express MMP-8, whereas knee cartilage with a high incidence of OA does constitutively express MMP-8, suggests that MMP-8 might be one of the key enzymes in the pathogenesis of osteoarthritis. This is further supported by our finding that the earliest signs of cartilage degradation were very similar to those found in IL-1 beta-treated explants.
关节软骨中聚集蛋白聚糖的丢失可能会导致骨关节炎（OA）的发展。类风湿性关节炎和骨关节炎患者的滑液中已鉴定出通过酶切在体内产生的人聚集蛋白聚糖的降解产物。一种基质金属蛋白酶（MMP），即基质溶解素（MMP-3），以及一种名为“聚集蛋白聚糖酶”的未鉴定蛋白酶被认为在病理条件下产生这些产物。到目前为止，体外仅显示一种蛋白酶，即中性粒细胞胶原酶（MMP-8）能够在“聚集蛋白聚糖酶”位点切割聚集蛋白聚糖分子。在本研究中，我们比较了正常人类供体两个不同关节软骨中MMP-3和MMP-8的存在和分布情况。我们确定了正常人类不同关节的关节软骨中是否表达MMP-8的mRNA。此外，我们比较了白细胞介素（IL）-1β体外刺激后人踝关节和膝关节软骨中MMP-8和MMP-3基因表达的差异。选择这两个关节是因为不同关节中症状性和影像学骨关节炎的发病率有所不同。膝关节是最常受累的关节，而踝关节（距小腿关节）相对较少受到影响。在正常膝关节未经处理的软骨中检测到MMP-8的信使核糖核酸，但在正常踝关节未经处理的软骨中未检测到。在大多数膝关节和踝关节软骨中可检测到MMP-3的信使核糖核酸。两种MMP的信使核糖核酸表达均可被IL-1β上调。最高剂量的IL-1β似乎对刺激MMP-3的信使核糖核酸最有效，而MMP-8的表达对较低剂量的IL-1β更敏感。骨关节炎发病率低的踝关节软骨不表达MMP-8，而骨关节炎发病率高的膝关节软骨组成性表达MMP-8，这一事实表明MMP-8可能是骨关节炎发病机制中的关键酶之一。我们发现软骨降解的最早迹象与IL-1β处理的外植体中发现的迹象非常相似，这进一步支持了这一观点。
