The effect of IL-17 on the production of proinflammatory cytokines and matrix metalloproteinase-1 by human periodontal ligament fibroblasts.

Objectives: To investigate the effects of IL-17 on IL-6, IL-1β, and matrix metalloproteinase (MMP-1) production, and to compare the MMP-1 production between the individual and combined effects of IL-1β and IL-6 in human periodontal ligament fibroblasts (HPDLF).
Materials and Methods: Human periodontal ligament fibroblasts were cultured with IL-17 for 0.5, 1, 4, 24, 48, and 72 h, and were cultured with IL-1β, IL-6/sIL-6R, or a combination of IL-1β and IL-6/sIL-6R for 24 h. To measure the mRNA levels of IL-6, IL-1β, and MMP-1, total RNA was extracted from the cultured HPDLF, and a real-time PCR analysis was performed. The protein levels of IL-6, IL-1β, and MMP-1 in supernatants were measured using enzyme-linked immunosorbent assays (ELISAs).
Results: IL-17 significantly increased the expression of IL-6 and MMP-1 mRNA and protein, while IL-17 transiently increased the expression of IL-1β mRNA. The combination of IL-1β and IL-6/sIL-6R induced significantly higher levels of MMP-1 protein than IL-1β alone.
Conclusions: IL-17 upregulated the production of IL-6 and MMP-1 sequentially in HPDLF. IL-6/sIL-6R may enhance the effects of IL-1β on MMP-1 production. The present results suggest that IL-17 induces MMP-1 production not only directly, but also indirectly by promoting IL-6 production, thus resulting in the degradation of collagens in the PDL.
(© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)