METALLOPROTEINASES IN RHEUMATOID ARTHRITIS

类风湿关节炎中高水平的促炎细胞因子诱导类风湿关节中基质金属蛋白酶的合成增加，导致关节软骨退化和关节功能丧失。转化生长因子β1可拮抗肿瘤坏死因子α和白介素1β诱导的正常人软骨细胞合成胶原酶-1、-2和-2的作用。我们认为这种生长因子可能有效地减少了类风湿关节炎胶原酶的合成，并将研究其作用机制。具体地说，我们将(A)测定RA滑膜组织和软骨移植产生的不同胶原酶的水平，并评估与转化生长因子-β1孵育的效果。(2)探讨转化生长因子β1抑制人软骨细胞胶原酶-3表达的机制。在正常和永生化的人类关节软骨细胞模型中，利用肿瘤坏死因子-α或白介素1-β刺激诱导胶原酶合成上调的模型，从转录或翻译控制的角度检验转化生长因子-β1对胶原酶-3的抑制作用。抑制胶原酶-3启动子所必需的区域/S将通过瞬时转染逐渐缺失的启动子结构来鉴定。我们将用DNA酶足迹和电泳迁移率分析进一步定义这些区域。(3)探讨转化生长因子-β1诱导胶原酶-3表达的机制。我们将确定低水平的炎性细胞因子是否允许转化生长因子-β1诱导人关节软骨细胞中的胶原酶-3。我们将定义与这一现象相关的转录因子。我们推测，转化生长因子-β1可能是RA组织中三种胶原酶的有效调节剂，可能是一种有用的软骨保护剂，可以调节胶原酶的合成，影响软骨的降解速度。

The high levels of pro-inflammatory cytokines in rheumatoid arthritis elicit increased synthesis of matrix metalloproteinases in the rheumatoid joint leading to degradation of articular cartilage and loss of joint function. Transforming growth factor beta 1 (TGF-beta1) acts antagonistically to the actions of TNF-alpha and IL-1beta decreasing synthesis of collagenase-1, -2 and -2 in normal human chrondrocytes stimulated with these cytokines. We propose this growth factor may be effective in reducing collagenase synthesis in RA and will study the mechanism of its effects. Specifically we will (a) Determine the levels of different collagenases produced by RA synovial tissue and cartilage explants and evaluate the effects of incubation with TGF-beta1. (2) Characterize the mechanism of TGFbeta1 inhibition of collagenase-3 expression in human chrondrocytes. Inhibition of collagenase-3 by TGF- beta1 will be examined with regard to transcriptional or translational control using a model of normal and immortalized human articular chrondrocytes stimulates with TNF-alpha or IL-1beta to induce up- regulation of collagenase synthesis. The region/s of the collagenase-3 promoter which are necessary for the inhibition will be identified with transient transfections of progressive deletions of the promoter constructs. We will further define these regions with DNase footprinting and electrophoretic shift mobility assays. (3) Characterize the mechanism of TGF-beta1 induction of collagenase-3 expression. We will determine if low levels of inflammatory cytokines are permissive for TGF-beta1 induction of collagenase-3 in human articular chrondrocytes. We will define the transcriptional factors which relate to this phenomena. We postulate that TGF-beta1 would be an effective modulator of all three collagenases in RA tissues and may be useful chondroprotective agent to regulate collagenase synthesis and influence the rate of cartilage degradation.