Cyclic tensile force-upregulated IL6 increases MMP3 expression by human periodontal ligament cells

Objective: Cyclic tensile force (CTF) modulates physiological responses of periodontal ligament (PDL) cells. PDL cells are mechanosensitive and are able to maintain tissue homeostasis; a process mediated by the expression of particular cytokines including interleukin 6 (IL6). It is unknown whether CTF-induced IL6 regulates the expression of MMPs, enzymes needed for tissue remodeling. Design: Human PDL cells were subjected to 10% elongation strain of CTF at a frequency of 60 rpm continuously for 6 h. RNA and proteins were extracted and analyzed for IL6 and MMP expression by quantitative real-time PCR and ELISA, respectively. Using a neutralizing anti-IL6 antibody and addition of recombinant human IL6 at concentrations of 0.1, 1, 10 ng.mL(-1) were performed to clarify whether CTF-upregulated IL6 increased MMP expression. Inhibitors of intracellular signaling molecules were employed to reveal possible pathway(s) of IL6-induced MMP expression. Results: CTF-induced IL6 expression coincided with an increased MMP3 expression. A neutralizing anti-IL6 antibody attenuated the CTF-increased MMP3 expression, whereas stimulating the cells with recombinant human IL6 increased MMP3 expression. Both PI3K and MAPK pathways were essential in the IL6 induced expression of MMP3. Conclusion: Our findings suggest a role of CTF in the modulation of expression of IL6 and MMP3 and thus in the regulation of homeostasis and remodeling of the periodontal ligament.