Objectives/hypothesis: Inflammation and its role in a coordinated fibroplastic response, which disrupts the structure of the vocal folds following injury, is critical. Cyclooxygenase-2 (COX-2) is an important enzyme involved in both inflammation and fibrosis; in addition, it is a prime target for therapeutic intervention. We sought to study this pathway in vocal fold fibroblasts to provide a foundation for future interventional studies.
Study design: In vitro.
Methods: Human vocal fold fibroblasts were incubated with IL-1 beta to determine the effects on COX-2 signaling, along with upstream regulatory mechanisms and downstream mediators of wound healing. In vitro methods to assess mRNA expression, as well as intracellular and secreted protein (sodium dodecyl sulfate polyacrylamide gel electrophoresis and enzyme-linked immunosorbent assay) were employed.
Results: IL-1 beta regulation of COX-2 mRNA and protein levels was dose and time dependent and IL-1 beta altered PGE(2) metabolism, via regulation of both synthetic and degradative enzymes. IL-1 beta increased nuclear factor (NF)-kappaB activation and nuclear translocation. Inhibition of the p50 and p65 subunits of NF-kappaB decreased IL-1 beta-induced COX-2 transcription. IL-1 beta also altered mRNA expression of four cell-surface prostaglandin receptors.
Conclusions: Inflammation and fibrosis are important in the vocal fold pathophysiologic response to injury. Our data suggest that COX-2 and PGE(2) are inducible in human vocal fold fibroblasts, and this response appears to be NF-kappaB-dependent. We purport this fundamental investigation will lead to increased insight regarding injury and repair in the vocal folds, with the ultimate goal of developing novel clinical care paradigms.