Mathy-Hartert M, Hogge L, Sanchez C, Deby-Dupont G, Crielaard J M, Henrotin Y
Bone and Cartilage Research Unit, Department of Physical Medicine, University of Liège, CHU Sart-Tilman, 4000 Liège, Belgium.
Osteoarthritis Cartilage. 2008 Jul;16(7):756-63. doi: 10.1016/j.joca.2007.10.009. Epub 2008 Mar 4.
Beside matrix metalloproteinases, reactive oxygen species (ROS) are the main biochemical factors of cartilage degradation. To prevent ROS toxicity, chondrocytes possess a well-coordinated enzymatic antioxidant system formed principally by superoxide dismutases (SODs), catalase (CAT) and glutathione peroxidase (GPX). This work was designed to assess the effects of interleukin (IL)-1beta and IL-6 on the enzymatic activity and gene expression of SODs, CAT and GPX in bovine chondrocytes.
Bovine chondrocytes were cultured in monolayer for 4-96 h in the absence or in the presence of IL-1beta (0.018-1.8ng/ml) or IL-6 (10-100 ng/ml). To study signal transduction pathway, inhibitors of mitogen-activated protein kinases (MAPK) (PD98059, SB203580 and SP600125) (5-20 microM) and nuclear factor (NF)-kappaB inhibitors [BAY11-7082 (1-10 microM) and MG132 (0.1-10 microM)] were used. SODs, CAT and GPX enzymatic activities were evaluated in cellular extract by using colorimetric enzymatic assays. Mn SODs, Cu/Zn SOD, extracellular SOD (EC SOD), CAT and GPX gene expressions were quantified by real-time and quantitative polymerase chain reaction (PCR).
Mn SOD and GPX activities were dose and time-dependently increased by IL-1beta. In parallel, IL-1beta markedly enhanced Mn SOD and GPX gene expressions, but decreased Cu/Zn SOD, EC SOD and CAT gene expressions. Induction of SOD enzymatic activity and Mn SOD mRNA expression were inhibited by NF-kappaB inhibitors but not by MAPK inhibitors. IL-6 effects were similar but weaker than those of IL-1beta.
In conclusion, IL-1beta, and to a lesser extend IL-6, dysregulates enzymatic antioxidant defenses in chondrocyte. These changes could lead to a transient accumulation of H(2)O(2) in mitochondria, and consequently to mitochondria damage. These changes contribute to explain the mitochondrial dysfunction observed in osteoarthritis chondrocytes.
除基质金属蛋白酶外，活性氧（ROS）是软骨降解的主要生化因素。为防止ROS毒性，软骨细胞拥有一个主要由超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GPX）组成的协调良好的酶促抗氧化系统。本研究旨在评估白细胞介素（IL）-1β和IL-6对牛软骨细胞中SOD、CAT和GPX的酶活性及基因表达的影响。
将牛软骨细胞单层培养4 - 96小时，分别在无IL-1β（0.018 - 1.8ng/ml）或IL-6（10 - 100 ng/ml）以及有IL-1β或IL-6的条件下培养。为研究信号转导途径，使用了丝裂原活化蛋白激酶（MAPK）抑制剂（PD98059、SB203580和SP600125）（5 - 20 microM）和核因子（NF）-κB抑制剂[BAY11 - 7082（1 - 10 microM）和MG132（0.1 - 10 microM）]。通过比色酶法在细胞提取物中评估SOD、CAT和GPX的酶活性。通过实时定量聚合酶链反应（PCR）对锰超氧化物歧化酶（Mn SOD）、铜/锌超氧化物歧化酶（Cu/Zn SOD）、细胞外超氧化物歧化酶（EC SOD）、CAT和GPX的基因表达进行定量分析。
IL-1β使Mn SOD和GPX的活性呈剂量和时间依赖性增加。同时，IL-1β显著增强Mn SOD和GPX的基因表达，但降低Cu/Zn SOD、EC SOD和CAT的基因表达。NF-κB抑制剂可抑制SOD酶活性和Mn SOD mRNA表达的诱导，但MAPK抑制剂无此作用。IL-6的作用与IL-1β相似，但较弱。
总之IL-1β，以及程度较轻的IL-6，会使软骨细胞中的酶促抗氧化防御失调。这些变化可能导致线粒体中过氧化氢（H₂O₂）的短暂积累，进而导致线粒体损伤。这些变化有助于解释骨关节炎软骨细胞中观察到的线粒体功能障碍。
