Dodge G R, Diaz A, Sanz-Rodriguez C, Reginato A M, Jimenez S A
Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107-5541, USA.
Arthritis Rheum. 1998 Feb;41(2):274-83. doi: 10.1002/1529-0131(199802)41:2<274::AID-ART11>3.0.CO;2-Z.
To determine the effects of interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha), alone or in combination, on the expression of aggrecan, biglycan, and decorin core protein genes in human chondrocytes.
Isolated human chondrocytes were cultured on poly(2-hydroxyethyl methacrylate)-coated plastic dishes to prevent the loss of cartilage-specific phenotype, and the effects of IFN gamma and TNF alpha, alone or in combination, on aggrecan, biglycan, and decorin core protein gene transcription and steady-state messenger RNA (mRNA) levels were examined.
The addition of IFN gamma (1.5 pM) or TNF alpha (0.3 pM) caused a decrease in the steady-state level of aggrecan mRNA (-25% and -15%, respectively), and the combination of these low-concentration cytokines caused a potent inhibition (-66%). These effects were the result of a decrease (-50%) in the transcription rate of the corresponding gene. At the concentrations used, IFN gamma did not alter the levels of biglycan mRNA or the transcription rates of the biglycan core protein gene. In contrast, TNF alpha decreased biglycan steady-state mRNA levels (-62%) and the biglycan core protein gene transcription rate (-18%). The combination of IFN gamma and TNF alpha resulted in a potentiation of the inhibitory effects of TNF alpha on biglycan mRNA levels (-79%) and transcription rate of the biglycan core protein gene (-46%). IFN gamma produced a modest decrease in decorin mRNA levels (-23%) and decorin core protein gene transcription rate (-17%). In contrast, TNF alpha resulted in a marked increase in decorin mRNA levels (+260%) that was not the result of transcriptional regulation. Notably, the combination of IFN gamma and TNF alpha potentiated the inhibitory effects of IFN gamma on decorin mRNA (-80%) and on the transcription of the corresponding gene (-43%). Similar results were obtained in fetal and adult articular chondrocytes.
These data demonstrate that 1) the expression of the core protein genes encoding the cartilage proteoglycans aggrecan, biglycan, and decorin is differentially regulated by IFN gamma and TNF alpha; 2) these effects are mediated by transcriptional and posttranscriptional mechanisms; and 3) the combination of the 2 cytokines causes a potent inhibitory effect on the expression of the genes for the core proteins of these 3 proteoglycans, which occurs largely at the transcriptional level. The inhibition of aggrecan, decorin, and biglycan core protein gene expression by the combination of IFN gamma and TNF alpha may contribute to the cartilage destruction that is characteristic of inflammatory joint diseases.
确定γ干扰素（IFNγ）和肿瘤坏死因子α（TNFα）单独或联合使用对人软骨细胞中聚集蛋白聚糖、双糖链蛋白聚糖和核心蛋白聚糖核心蛋白基因表达的影响。
将分离出的人软骨细胞培养在涂有聚（甲基丙烯酸2-羟乙酯）的塑料培养皿上，以防止软骨特异性表型丧失，并检测IFNγ和TNFα单独或联合使用对聚集蛋白聚糖、双糖链蛋白聚糖和核心蛋白聚糖核心蛋白基因转录及稳态信使核糖核酸（mRNA）水平的影响。
添加IFNγ（1.5 pM）或TNFα（0.3 pM）导致聚集蛋白聚糖mRNA的稳态水平下降（分别下降25%和15%），这两种低浓度细胞因子联合使用产生了强效抑制作用（-66%）。这些作用是相应基因转录率下降（-50%）的结果。在所使用的浓度下，IFNγ未改变双糖链蛋白聚糖mRNA水平或双糖链蛋白聚糖核心蛋白基因的转录率。相反，TNFα降低了双糖链蛋白聚糖的稳态mRNA水平（-62%）和双糖链蛋白聚糖核心蛋白基因的转录率（-18%）。IFNγ和TNFα联合使用增强了TNFα对双糖链蛋白聚糖mRNA水平（-79%）和双糖链蛋白聚糖核心蛋白基因转录率（-46%）的抑制作用。IFNγ使核心蛋白聚糖mRNA水平适度下降（-23%）和核心蛋白聚糖核心蛋白基因转录率下降（-17%）。相反，TNFα导致核心蛋白聚糖mRNA水平显著升高（+260%），这并非转录调控的结果。值得注意的是，IFNγ和TNFα联合使用增强了IFNγ对核心蛋白聚糖mRNA（-80%）及其相应基因转录（-43%）的抑制作用。在胎儿和成人关节软骨细胞中也获得了类似结果。
这些数据表明：1）编码软骨蛋白聚糖聚集蛋白聚糖、双糖链蛋白聚糖和核心蛋白聚糖的核心蛋白基因的表达受到IFNγ和TNFα的差异调节；2）这些作用由转录和转录后机制介导；3）这两种细胞因子联合使用对这三种蛋白聚糖核心蛋白的基因表达产生强效抑制作用，这主要发生在转录水平。IFNγ和TNFα联合使用对聚集蛋白聚糖、核心蛋白聚糖和双糖链蛋白聚糖核心蛋白基因表达的抑制作用可能导致炎症性关节疾病所特有的软骨破坏。
