Ciprofloxacin up‐regulates tendon cells to express matrix metalloproteinase‐2 with degradation of type I collagen

Abstract

Abstract Ciprofloxacin‐induced tendinopathy and tendon rupture have been previously described, principally affecting the Achilles tendon. This study was designed to investigate the effect of ciprofloxacin on expressions of matrix metalloproteinases (MMP)‐2 and ‐9, tissue inhibitors of metalloproteinase (TIMP)‐1 and ‐2 as well as type I collagen in tendon cells. Tendon cells intrinsic to rat Achilles tendon were treated with ciprofloxacin and then underwent MTT (tetrazolium) assay. Real‐time reverse‐transcription polymerase chain reaction (RT‐PCR) and Western blot analysis were used, respectively, to evaluate the gene and protein expressions of type I collagen, and MMP‐2. Gelatin zymography was used to evaluate the enzymatic activities of MMP‐2 and ‐9. Reverse zymography was used to evaluate TIMP‐1 and ‐2. Immunohistochemical staining for MMP‐2 in ciprofloxacin‐treated tendon explants was performed. Collagen degradation was evaluated by incubation of conditioned medium with collagen. The results revealed that ciprofloxacin up‐regulated the expression of MMP‐2 in tendon cells at the mRNA and protein levels. Immunohistochemistry also confirmed the increased expressions of MMP‐2 in ciprofloxacin‐treated tendon explants. The enzymatic activity of MMP‐2 was up‐regulated whereas that of MMP‐9, TIMP‐1 or TIMP‐2 was unchanged. The amount of secreted type I collagen in the conditioned medium decreased and type I collagen was degraded after ciprofloxacin treatment. In conclusion, ciprofloxacin up‐regulates the expressions of MMP‐2 in tendon cells and thus degraded type I collagen. These findings suggest a possible mechanism of ciprofloxacin‐associated tendinopathy. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:67–73, 2011