A critical role for collagen II in cartilage matrix degradation: Collagen II induces pro‐inflammatory cytokines and MMPs in primary human chondrocytes

Abstract

We report a process that results in the acceleration of matrix degradation in human articular cartilage, a phenomenon commonly observed in osteoarthritis (OA). The study was conducted by (1) examining the potential of collagen II in modulating the gene expression profile of primary human chondrocytes (PHCs), and (2) investigating the involvement of pro-inflammatory signaling cascades. We first tested the collagen II-dependent induction of pro-inflammatory cytokines and matrix metalloproteinases (MMPs) in PHCs. PHCs were incubated with or without monomeric (i.e., nonfibrillar) collagen II. Cells were then analyzed by RT-PCR for the expression of MMP1, MMP3, MMP13, MMP14, and IL-1b. ELISA was used to quantify IL-6 and IL-8 release. To examine the influence of collagen II signaling, specifically the role of MAPK p38, a p38-inhibitor was added prior to collagen treatment. Changes in IkB concentration were monitored by immunoblot analysis to detect NFkB signaling. Results indicated that incubation of PHCs with collagen II did produce a dose-dependent induction of MMP1, MMP3, MMP13, MMP14, as well as cytokines IL-1b, IL-6, and IL-8. At the same time, inhibition of p38 and IkB degradation revealed that collagen II-dependent gene induction also involves MAPK p38 and NFkB signaling. Thus, we provide evidence for a collagen II-dependent feed-forward mechanism whereby collagen II induces first MMPs and pro-inflammatory cytokines and then release of collagen II fragments from mature collagen II fibers. This, in turn, induces more pro-inflammatory cytokines and MMPs, and the process is repeated, which results in the acceleration and perpetuation of cartilage matrix degradation. Keywords: collagen; chondrocytes; osteoarthritis; matrix metalloproteinases; Osteoarthritis (OA) is a chronic disease of synovial joints. Although the etiology and pathogenesis of OA are poorly understood, we do know that degradation of the extracellular matrix (ECM) in articular cartilage is a major cause of joint destruction. Cartilage degradation is mediated by matrix metalloproteinases (MMPs), principally MMP1, MMP3, and MMP13.1-4 MMP1 (collagenase-1) and MMP13 (collagenase-3) are able to cleave mature collagen fibers and initiate further collagen degradation. MMP3 (stromelysin-1) cleaves a variety of ECM components, including proteoglycans, collagens, and procollagens.5 Chondrocytes respond to various stimuli, such as pro-inflammatory cytokines or mechanical load, by their induction of MMPs. Collagen II may fulfill a similar function in that both collagen II and a synthetic 29-mer collagen peptide have recently been shown to induce MMP2, MMP3, MMP9, and MMP13 in primary bovine articular chondrocytes. 6 According to other studies, collagen II can induce MMP13 in the immortalized human chondrocyte cell line C-28/I2, which transiently expresses discoidin domain receptor-2 (DDR-2) cDNA. 4 Thus far, however, the induction of MMPs by collagen II in PHCs has not been investigated. The induction of collagenase-1 or MMP14 (membranetype MMP1, MT...

Coptisine Prevented IL-β-Induced Expression of Inflammatory Mediators in Chondrocytes

“…There is substantial evidence that inhibition of MMP production could inhibit the progression of OA [21][22][23]. In addition, IL-1β stimulates chondrocytes to release proteolytic enzymes and MMPs, which are key regulators of cartilage destruction [24]. Herein, we found that coptisine inhibited the IL-1β-dependent upregulation of the expression of MMP-3 and MMP-13 in chondrocytes.…”

Metalloproteinases and Metalloproteinase Inhibitors in Age-Related Diseases

“…Proteolytic fragments also stimulate the release of NO, chemokines and cytokines [455]. Of note, it has been observed that human chondrocytes cultured with intact monomeric type II collagen induced expression of MMP-1, -3, -13, -14, as well as that of IL-1 , IL-6, and IL-8 [456].…”

Nobiletin Inhibits Expression of Inflammatory Mediators and Regulates JNK/ERK/p38 MAPK and PI3K/Akt Pathways in Human Osteoarthritic Chondrocytes

“…Elevated levels of IL-1β have been observed in synovial fluid in OA [22]. IL-1β induces the expression of MMPs, such as MMP1, MMP3 and MMP13 that contribute to matrix degradation [23]. In addition, IL-1β induces the expression of iNOS and COX-2 and as well enhance the production of NO, PGE2 and IL-6 [11].…”

“…To further analyse the effects of nobiletin, we assessed the expression of NF κB and MAPK signalling pathway proteins. NF-κB is one of the most important cytokineinduced transcription factors that critically regulate the expression of MMPs, COX-2, iNOS and other inflammatory cytokines [23]. Normally, NF-κB is bound to IκB inhibitor proteins in the cytoplasm.…”