Reginato A M, Sanz-Rodriguez C, Diaz A, Dharmavaram R M, Jimenez S A
Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107.
Biochem J. 1993 Sep 15;294 ( Pt 3)(Pt 3):761-9. doi: 10.1042/bj2940761.
To examine the possibility that cytokines produced in inflamed joint tissues may contribute to the loss of articular cartilage by causing inhibition of synthesis of cartilage-specific matrix macromolecules, we studied the effects of interferon gamma (IFN gamma) and tumour necrosis factor alpha (TNF alpha), alone and in combination, on the expression of the genes for types-II, -IX and -XI collagens in cultured human chondrocytes. Chondrocytes isolated from human fetal epiphyseal cartilage by sequential enzymic digestions were cultured in the presence of IFN gamma (30 pM), TNF alpha (15 pM) or a combination of suboptimal concentrations of both cytokines (1.5 pM IFN gamma plus 0.3 pM TNF alpha). IFN gamma caused a maximal decrease of 23.3-32.6% in the biosynthesis of collagen by chondrocytes. TNF alpha was a more potent inhibitor causing a 42.8-45.3% decrease at one-half the concentration of IFN gamma. A synergistic inhibitory effect of 58.2% was observed with the combination of 1.5 pM IFN gamma plus 0.3 pM TNF alpha. Electrophoretic analysis of the biosynthesized proteins showed a co-ordinate decrease in the production of the three cartilage-specific collagen types II, IX and XI. These effects were accompanied by parallel changes in the steady-state levels of their corresponding mRNAs. In vitro transcription assays showed that the collagen inhibitory effects of the cytokines occurred largely at the transcriptional level. Similar effects of the cytokines were observed on biosynthesis of types-II, -IX and -XI collagens and steady-state mRNA levels for type-II collagen by chondrocytes obtained from adult articular cartilage. These observations indicate that IFN gamma and TNF alpha can induce a synergistic inhibition of the synthesis of cartilage-specific collagens by fetal and adult human chondrocytes and suggest that these effects may contribute to the articular cartilage loss that occurs in inflammatory joint diseases.
为了研究炎症关节组织中产生的细胞因子是否可能通过抑制软骨特异性基质大分子的合成而导致关节软骨丢失，我们研究了干扰素γ（IFNγ）和肿瘤坏死因子α（TNFα）单独及联合作用对培养的人软骨细胞中Ⅱ型、Ⅸ型和Ⅺ型胶原基因表达的影响。通过连续酶消化从人胎儿骺软骨分离的软骨细胞在IFNγ（30 pM）、TNFα（15 pM）或两种细胞因子次优浓度组合（1.5 pM IFNγ加0.3 pM TNFα）存在的情况下培养。IFNγ使软骨细胞胶原生物合成最大减少23.3% - 32.6%。TNFα是一种更强效的抑制剂，在IFNγ浓度一半时导致减少42.8% - 45.3%。观察到1.5 pM IFNγ加0.3 pM TNFα组合产生58.2%的协同抑制作用。对生物合成蛋白质的电泳分析显示三种软骨特异性胶原Ⅱ型、Ⅸ型和Ⅺ型的产生协同减少。这些作用伴随着其相应mRNA稳态水平的平行变化。体外转录分析表明细胞因子对胶原的抑制作用主要发生在转录水平。从成人关节软骨获得的软骨细胞对Ⅱ型、Ⅸ型和Ⅺ型胶原生物合成以及Ⅱ型胶原稳态mRNA水平也观察到细胞因子的类似作用。这些观察结果表明IFNγ和TNFα可诱导胎儿和成人人类软骨细胞对软骨特异性胶原合成的协同抑制，并提示这些作用可能导致炎症性关节疾病中发生的关节软骨丢失。
