Endogenous production of reactive oxygen species is required for stimulation of human articular chondrocyte matrix metalloproteinase production by fibronectin fragments

Department of Biochemistry, Section of Rheumatology, Rush Medical College, Chicago, IL, USA.
Free Radical Biology and Medicine (Impact Factor: 5.74). 05/2007; 42(9):1350-8. DOI: 10.1016/j.freeradbiomed.2007.01.035
Source: PubMed


The objective of the present study was to determine if reactive oxygen species (ROS) are required as secondary messengers for fibronectin fragment-stimulated matrix metalloproteinase (MMP) production in human articular chondrocytes. Cultured cells were stimulated with 25 microg/ml of the alpha5beta1 integrin-binding 110-kDa fibronectin fragment (FN-f) in the presence and absence of various antioxidants including Mn(III) tetrakis(4-benzoic acid)porphyrin (MnTBAP). FN-f stimulation significantly increased intracellular levels of ROS in articular chondrocytes. Pretreatment of cells with 250 microM MnTBAP or 40 mM N-acetyl-L-cysteine, but not inhibitors of nitric oxide synthase, completely prevented FN-f-stimulated MMP-3, -10, and -13 production. MnTBAP also blocked FN-f-induced phosphorylation of the MAP kinases and NF-kappaB-associated proteins and blocked activation of an NF-kappaB promoter-reporter construct. Overexpression of catalase, superoxide dismutase, or glutathione peroxidase also inhibited FN-f-stimulated MMP-13 production. Preincubation of chondrocytes with rotenone, an inhibitor of the mitochondrial electron transport chain, or nordihydroguaiaretic acid (NDGA), a selective 5-lipoxygenase inhibitor, partially prevented FN-f-stimulated MMP-13 production and decreased MAP kinase and NF-kappaB phosphorylation. These results show that increased production of ROS but not nitric oxide as obligatory secondary messengers in the chondrocyte FN-f signaling pathway leads to the increased production of MMPs, including MMP-13.

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    • "α5β1 integrin may also promote catabolic responses in chondrocytes, inducing the expression of matrix metalloproteinases and proinflammatory cytokines [27,28]. Reactive oxygen species may be generated in chondrocytes upon the activation of α5β1 integrin [29]. In those catabolic responses, ERK, p38 mitogen-activated protein kinase, c-Jun N-terminal kinases, and protein kinase C pathways may be activated by this integrin [27,28]. "
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    • "Furthermore, the enhanced levels of proteinase enzymes cleave both collagens and proteoglycans, resulting in an increase in matrix fragments which stimulate abnormal integrin signals. The accumulation of matrix fragments enhance catabolic protease-driven pathways that override anabolic events and contribute to eventual loss of matrix components and structural damage [75] [76] [77] [78] [79]. Abnormal mechanical stimuli are likely to contribute to matrix damage which might shift balance of cell metabolism and lead to the onset of OA. "
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    • "The α 1β1 and α 5β1 integrins function as receptors for fragments of collagen and fibronectin, respectively. The stimulation of α 5β1 integrin by integrin-activating antibodies or fibronectin fragments results in increased MMP production and requires reactive oxygen species [169]. In contrast, the discoidin domain receptor-2 specifically increases MMP-13 production by recognizing intact type II collagen fibrils that have been denuded by proteoglycans, as occurs in osteoarthritis [170,171], but its role in RA has not been determined. "
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