Collagen and Aggrecan Degradation Is Blocked in Interleukin-1-Treated Cartilage Explants by an Inhibitor of IκB Kinase through Suppression of Metalloproteinase Expression

Abstract

It has previously been shown that BMS-345541 [4(2Ј-aminoethyl)amino-1,8-dimethylimidazo(1,2-a)quinoxaline], a highly-selective inhibitor of IB kinase (IKK), blocks both inflammation and joint destruction in murine collagen-induced arthritis. Although this agent has been shown to inhibit nuclear factor-Bdependent cytokine expression in mice, we examined whether the inhibitor directly inhibits cytokine-driven metalloproteinase expression and cartilage degradation. In SW-1353 human chondrosarcoma cells, BMS-345541 inhibited interleukin-1 (IL-1)-dependent expression of matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 in a concentration-dependent manner. IL-1 treatment failed to induce and BMS-345541 did not inhibit the expression of aggrecanases ADAMTS-4 (a disintegrin and metalloproteinase domain with thrombospondin motif) and AD-AMTS-5, as well as the tissue inhibitor of metalloproteinase-3. In bovine cartilage explant cultures stimulated with IL-1 to induce aggrecan and collagen degradation over 3 weeks of culture, BMS-345541 was effective in inhibiting the degradation of both aggrecan and collagen. Secreted ADAMTS-4 was not inhibited by BMS-345541 in these explants, whereas ADAMTS-5 secretion was blocked in the same concentration range that inhibited aggrecan degradation. The ability of the IKK inhibitor to block aggrecan and collagen degradation through suppression of metalloproteinase expression, coupled with its ability to block inflammatory cytokine production, shows IKK to be a promising target for the development of novel agents to treat arthritic diseases.Degenerative joint disorders such as osteoarthritis (OA) and rheumatoid arthritis (RA) are characterized by the destruction and loss of articular cartilage and an imbalance of proinflammatory cytokines. In both disorders, the chondrocytes appear to play an important role in the pathogenesis of disease. Although chondrocytes are the primary source of type II collagen and aggrecan, two of the most important components of the cartilage matrix, these cells also produce proteolytic enzymes, which degrade collagen and aggrecan/ proteoglycan when stimulated with interleukin-1 (IL-1) or tumor necrosis factor-␣ (TNF-␣). Overproduction of these enzymes results in the erosion of articular cartilage, destruction of tissue and bone, and joint abnormalities. As evidenced by the efficacy of therapies targeting TNF-␣ (e.g., infliximab and etanercept) or IL-1 (e.g., anakinra), these cytokines play a critical role in both the inflammatory and destructive mechanisms of RA. In OA, IL-1 also appears to play a pivotal role in the degenerative process by driving collagen and aggrecan degradation (for a review, see Chevalier, 1997).The transcription factor nuclear factor-B (NF-B) mediates much of the downstream effects of both TNF-␣ and IL-1, including the transcription of matrix metalloproteinases (MMP) and other cytokines (Li and Verma, 2002). In unactivated cells, NF-B is inhibited by an interaction with an IB protein (e.g., IB␣, IB␤, and IB⑀). An essential step i...

The peroxisome proliferator–activated receptor γ agonist pioglitazone reduces the development of cartilage lesions in an experimental dog model of osteoarthritis: In vivo protective effects mediated through the inhibition of key signaling and catabolic pathways

“…Therefore, the effect of pioglitazone on iNOS synthesis could very well result from a combined inhibition of both pathways. This finding with regard to the inhibition of the activation of NF-B by pioglitazone could also explain the action of the drug in inhibiting ADAMTS-5, since the synthesis of this enzyme was reported to be blocked by an I B kinase inhibitor, BMS-345541 (46). The inhibition of the activation of NF-B by pioglitazone could be one of several possible mechanisms of action, as previously reported (18).…”

Metalloproteinases and Metalloproteinase Inhibitors in Age-Related Diseases

“…These data suggest that aggrecan degradation occurs in a NF-B dependent manner [501]. Conversely, ADAMTS-5 has been found to be NF-B independent and to lack B elements on its promoter [500].…”

Periodic, Partial Inhibition of IκB Kinase β-Mediated Signaling Yields Therapeutic Benefit in Preclinical Models of Rheumatoid Arthritis

“…The IKK␤-NF-B pathway has also been shown to regulate inflammatory cell recruitment through NF-Bdependent expression of cell adhesion molecules such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 and chemoattractants such as monocyte chemoattractant protein-1 and IL-8 (Viemann et al, 2004), although the effects of BMS-066 against these endpoints were not measured. IKK␤ also regulates the expression of matrix metalloproteinases that degrade cartilage and bone, and this can be blocked with an IKK␤ inhibitor (Pattoli et al, 2005).…”

“…After a 1-h incubation at 37°C, LPS (Salmonella typhosa; Sigma-Aldrich, St. Louis, MO) was added to cells to a final concentration of 50 ng/ml and allowed to incubate 4 h at 37°C at 5% CO 2 , at which time cells were harvested and prepared for RNA isolation. Quantitative real-time polymerase chain reaction was performed for TNF-␣, IL-6, the p19 subunit of IL-23, and the common p40 subunit of IL-12/IL-23 with procedures reported previously (Pattoli et al, 2005).…”