Inhibitory Effects of Insulin-like Growth Factor-1 and Osteogenic Protein-1 on Fibronectin Fragment- and Interleukin-1β-stimulated Matrix Metalloproteinase-13 Expression in Human Chondrocytes

Abstract

Matrix metalloproteinase-13 (collagenase-3), a member of the family of matrix metalloproteinases (MMPs), plays a major pathological role in the cartilage destruction of arthritis. A dramatic up-regulation of MMP-13 by inflammatory cytokines such as interleukin (IL)-1␤ or by fibronectin fragments has been observed in chondrocytes. In this study, we investigated the inhibitory effects of insulin-like growth factor-1 (IGF-1) and osteogenic protein-1 (OP-1) on the expression of MMP-13, which was induced by fibronectin fragment or IL-1␤ in human immortalized or human primary chondrocytes. IGF-1 and OP-1 each significantly reduced the basal level as well as fibronectin fragment-or IL-1␤-stimulated transcription of the MMP-13 gene in a dosedependent fashion with the corresponding decreases in the protein level of MMP-13. The most prominent suppressive effect was observed by the combination of IGF-1 and OP-1, which decreased the basal promoter activity by 60% and almost completely abrogated the fibronectin fragmentstimulated MMP-13 promoter activity. OP-1 was found to enhance mRNA levels of IGF-1 and the IGF-1 receptor, the latter of which appeared to be responsible for the combined effect of IGF-1 and OP-1. The suppressive effect of IGF-1 and OP-1 on MMP-13 expression was due in part to downregulation of the expression of pro-inflammatory cytokines and the activity of their intermediate molecules, including NF-B and AP-1 factors. We propose that IGF-1 and OP-1 could be key physiological regulators of MMP-13 gene expression and that the combination of IGF-1 and OP-1 may be useful in controlling the excess catabolic activity in arthritis.Cartilage homeostasis is a well synchronized balance between anabolic and catabolic processes. During the development of osteoarthritis, this balance is disrupted resulting in progressive degradation of the articular cartilage (1). Studies have demonstrated that members of the matrix metalloproteinase (MMP) 1 family are the major pathophysiological mediators of the cartilage destruction process in osteoarthritis (2). Recently, in vitro, clinical, and transgenic studies have provided evidence that chondrocyte MMP-13 (collagenase-3) is a leading candidate enzyme mediating the degradation of type II collagen in osteoarthritis (2-4). A dramatic up-regulation of MMP-13 gene expression in response to inflammatory cytokines, such as interleukin-1␤ (IL-1␤) (5), or by fibronectin fragment (Fn-f) (6) has been observed in chondrocytes. However, there is limited knowledge of the cellular mechanisms that regulate MMP-13 gene expression in chondrocytes. Accumulating evidence demonstrates that the bone morphogenetic proteins (BMPs), a subfamily of the transforming growth factor-␤ superfamily, are inhibitors of MMP-13 expression in human fetal chondrocytes (7) or rat osteoblast-enriched cells (8, 9). Upon ligand binding, the specific serine/threonine kinase activity of BMP receptors (type I or II) transduce signals (10) by allowing the association of Smad1 and Smad4 in the cytoplasm followed by the tran...

Articular chondrocytes express the receptor for advanced glycation end products: Potential role in osteoarthritis

“…This was tested in chondrocytes by treating cultured cells with the 110-kd fibronectin fragment and the cytokine IL-1␤. Both these factors are found in OA cartilage (14,30) and have been shown to stimulate signaling pathways that result in increased NF-B activity (31,32). Consistent with this, both fibronectin fragments and IL-1␤ stimulated RAGE expression (mean Ϯ SEM 172 Ϯ 18% of control and 185 Ϯ 24% of control, respectively), measured using real-time PCR (Figure 4).…”

Mechanical confinement regulates cartilage matrix formation by chondrocytes

“…The concentration of IL-1Ra was determined from our own pilot studies and the value is comparable to that used for a similar purpose in another study 56,57 . Levels of LDH and gene expression of MMP13 and ADAMTS4 were measured as described above after seven days of culture.…”

IGF-I stimulation of proteoglycan synthesis by chondrocytes requires activation of the PI 3-kinase pathway but not ERK MAPK

“…Although a molecular approach using transfection of dominantnegative kinase constructs might seem appropriate to confirm the chemical inhibition results, there are limitations of this approach in experiments using primary adult human chondrocytes. Adult human chondrocytes are difficult to transfect efficiently, and in previous work we had to use co-transfection of promoter-reporter constructs to measure the effects of dominant-negative kinase constructs [36,37]. Since the subject of interest in the present study was proteoglycan synthesis, it was not feasible to use this approach.…”