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TMŽ . Atlas cDNA cell interaction arrays CLONTECH were used to examine degenerate tissue from four patients with Achilles tendon disorders, in order to identify changes in expression of genes important in cell᎐cell and cell᎐matrix Ž . interactions. The greatest difference between normal post-mortem and degenerate tissue samples was in the level of MMP-3 Ž . stromelysin mRNA, which was down-regulated in all the degenerate samples. Quantitative RT-PCR assay of RNA extracted from paired 'normal' and degenerate Achilles tendon tissue samples taken from tendons during surgery mirrored the results of the arrays. Levels of MMP-3 mRNA were lower, whereas levels of type-I and type-III collagen mRNAs were significantly higher, in the degenerate compared to the 'normal' samples. Immunoblotting of proteins extracted from the same tendon samples showed that three of four normal tissue samples taken from individuals without apparent tendon disorder had much higher levels of MMP-3 protein than 'normal' or degenerate samples from patients with tendinosis. We suggest that MMP-3 may play an important role in the regulation of tendon extracellular matrix degradation and tissue remodelling. ᮊ

Objective. To study the interaction of interleukin-la (IL-la) and oncostatin M (OSM) in promoting cartilage collagen destruction.Methods. Bovine, porcine, and human cartilage and human chondrocytes were studied in culture. The levels of collagenase (matrix metalloproteinase 1 [MMP-I]) and tissue inhibitor of metalloproteinases 1 (WMP-1) were measured by bioassay and enzyme-linked immunosorbent assay (ELISA). The levels of OSM in rheumatoid synovial fluid were measured by ELISA.Results. When combined with OSM, 1L-la, ILlp, and tumor necrosis factor a released proteoglycan and collagen from cartilage. OSM was the only member of the IL-6 family to have this effect. Human tendon also responded to IL-la and OSM. OSM increased the production of MMP-1 and TIMP-1 but when combined with IL-la, synergistically promoted MMP-1 production in human chondrocytes and synovial fibroblasts. High levels of OSM were found in human rheumatoid synovial fluids, and confocal microscopy showed that OSM was produced by macmphages in rheumatoid synovial tissue. Conclusion. These results highlight an important

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Objective. To determine whether the fluoroquinolone antibiotic ciprofloxacin, which can cause tendon pain and rupture in a proportion of treated patients, affects the expression of matrix metalloproteinases (MMPs) in human tendon-derived cells in culture.Methods. Cell cultures were derived from 6 separate tendon explants, and were incubated in 6-well culture plates for 2 periods of 48 hours each, with ciprofloxacin (or DMSO in controls) and interleukin-1␤ (IL-1␤), alone and in combination. Samples of supernatant medium from the second 48-hour incubation were assayed for MMPs 1, 2, and 3 by Western blotting. RNA was extracted from the cells and assayed for MMP messenger RNA (mRNA) by semiquantitative reverse transcription-polymerase chain reaction, with normalization for GAPDH mRNA.Results. Unstimulated tendon cells expressed low or undetectable levels of MMP-1 and MMP-3, and substantial levels of MMP-2. IL-1␤ induced a substantial output of both MMP-1 and MMP-3 into cell supernatants, reflecting increases (typically 100-fold) in MMP mRNA, but had only minor effects on MMP-2 expression. Ciprofloxacin had no detectable effect on MMP output in unstimulated cells. Preincubation with ciprofloxacin potentiated IL-1␤-stimulated MMP-3 output, reflecting a similar effect on MMP-3 mRNA expression. Ciprofloxacin also potentiated IL-1␤-stimulated MMP-1 mRNA expression, but did not potentiate the output of MMP-1, and had no significant effects on MMP-2 mRNA expression or output.Conclusion. Ciprofloxacin can selectively enhance MMP expression in tendon-derived cells. Such effects might compromise tendon microstructure and integrity.