[Effects of tensile strain on the expression of Runx2/Cbfalpha1 in osteoblasts cultivated with inflammatory stimulus]

To determine the effects of tensile strain on the expression of core binding factor alpha1 (Runx2/Cbfalpha1) in osteoblasts cultivated in Pg-LPS stimulated RAW264.7 culture supernatant.

Osteoblasts MC3T3-E1 were cultivated in LPS stimulated monocyte culture supernatant for 24 h. Then, a four-point bending device was used to perform a single period of tensile strain (1000 microm strain, 3000 microm strain respectively) on osteoblasts for 0 h, 0.5 h, 1 h, 2 h, 3 h, 6 h. Non-inflammatory stimuli were set up as control. The expression of Runxr2/Cbfalpha1 mRNA in MC3T3-E1 cells was examined by real-time RT-PCR.

With the mechanical loading, the expression of Runx2/Cbfalpha1 mRNA increased in both inflammatory and non-inflammatory groups of osteoblasts and reached the peak after 6 h. The inflammatory group had lower expression of Runx2/Cbfalpha1 mRNA than that of the non-inflammatory group (P<0.05). The varied strain level did not change the expression of Runx2/Cbfalpha1 mRNA within 3 hours. But after 6 hours, the 3000 microm strain induced higher expression of Runx2/Cbfalpha1 mRNA than the 1000 microm strain.

Inflammation inhibits the tensile strain induced expression of Runx2/Cbfalpha1 in osteoblasts. Precaution needs to be paid to orthodontic treatment on patients with quiescent periodontitis.