[The Effects of NF-kappaB Signalling on the TNF-α induced Ratios of MMPs to TIMPs in Chondrocytes].

OBJECTIVES: To explore the influence of the NF-κB inhibitor (bay11-7082) on tumor necrosis factor-α (TNF-α)-induced different ratios of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in chondrocytes. METHODS: Chondrocytes were isolated from the knee joint of a 1-day old mouse by trypsin digestion method. Hematoxylin-Eosin (HE) stain was used to show the morphology of isolated chondrocytes; Semi-quantitative PCR was applied to analyze the influence of bay11-7082 on gene expressions of TNF-α-induced MMPsand TIMPsin chondrocytes; Zymography was used to elucidate activities of the gelatinases induced by TNF-α and/or bay11-7082. RESULTS: TNF-α up-regulated gene expressiosn of the MMPsand TIMPs(P<0.05). The ratios of MMPs/TIMPswere mostly increased except the part of MMP-1. Bay11-7082 could reduce TNF-α-induced MMPsand TIMPsgene expressions, and could make the increased ratio of MMPs/TIMPsdropped to the normal level of chondrocytes. Similar results were observed at the protein level of the gelatinases by zymography. CONCLUSIONS: TNF-α-induced high ratios of MMPs/TIMPs could partiallyexplain over-degradation of cartilage extracellular matrix in osteoarthritis (OA). Blockage of NF-κB with bay11-7082 might provide a possible therapeutic strategy for the OA deterioration.

The effects of interleukin-1ß in modulating osteoclast-conditioned medium's influence on gelatinases in chondrocytes through mitogen-activated protein kinases.

Osteoarthritis is recognised to be an interactive pathological process involving the cartilage, subchondral bone and synovium. The signals from the synovium play an important role in cartilage metabolism, but little is known regarding the influence of the signalling from bone. Additionally, the collagenases and stromelysin-1 are involved in cartilage catabolism through mitogen-activated protein kinase (MAPK) signalling, but the role of the gelatinases has not been elucidated. Here, we studied the influence of osteoclastic signals on chondrocytes by characterising the expression of interleukin-1ß (IL-1ß)-induced gelatinases through MAPK signalling. We found that osteoclast-conditioned media attenuated the gelatinase activity in chondrocytes. However, IL-1ß induced increased levels of gelatinase activity in the conditioned media group relative to the mono-cultured chondrocyte group. More specifically, IL-1ß restored high levels of gelatinase activity in c-Jun N-terminal kinase inhibitor-pretreated chondrocytes in the conditioned media group and led to lower levels of gelatinase activity in extracellular signal-regulated kinase or p38 inhibitor-pretreated chondrocytes. Gene expression generally correlated with protein expression. Taken together, these results show for the first time that signals from osteoclasts can influence gelatinase activity in chondrocytes. Furthermore, these data show that IL-1ß restores gelatinase activity through MAPK inhibitors; this information can help to increase the understanding of the gelatinase modulation in articular cartilage.