Effects of compressive stress on the expression of M-CSF, IL-1β, RANKL and OPG mRNA in periodontal ligament cells

Objective: The aim of this study was to determine if human PDL cells can produce osteoclastogenic mRNA and examine how compressive stress affects the expression of osteoclastogenic mRNA in human PDL cells. Methods: Human PDL cells were obtained from biscupids extracted for orthodontic treatment. The compressive force was adjusted by increasing the number of cover glasses. PDL cells were subjected to a compressive force of 0.5, 1.0, 2.0, 3.0 or 4.0 g/cm2 for 0.5, 1.5, 6, 24 or 48 hours. Reverse transcription polymerase chain reaction (RT-PCR) analysis was performed to examine levels of M-CSF, IL-1β, RANKL, OPG mRNA expression. Results: Human PDL cells could produce M-CSF mRNA. Human PDL cells under compressive stress showed increased M-CSF, IL-1β and RANKL mRNAs expression in a force (up to 2 g/cm2) and time-dependent manner. However, OPG mRNA expression was constant regardless of the level and duration of stress. Conclusions: Continuous compressive stress induced the mRNA expression of osteoclastogenic cytokines including M-CSF, RANKL, IL-1β in PDL cells. Together with an unchanged OPG mRNA level, these results suggest that compressive stress-induced osteoclastogenesis in vivo is partly controlled by M-CSF, RANKL and IL-1β expression in PDL cells.