OBJECTIVETo investigate the changes of inflammation-related cytokine expression profiles in human periodontal ligament fibroblasts (hPDLF) under mechanical stress.

METHODSThe periodontal ligament attached to the mid-third part of the fresh root of young premolars extracted for orthodontic treatment was scalped and removed. hPDLFs were cultured by the method of digesting by I-type collagenase combined with tissue adhering, and then isolated and purified by cells passages. hPDLFs were then divided into two groups, group with mechanical force and group without mechanical force and then cultured for 24 h. Employing cytokine-microarray analysis to assess, in a comprehensive manner compared to the hPDLFs culture system without a static force. The quantity of different cytokine-related genes in hPDLFs was analyzed by means of quantitative with the special primers of up-and down-regulated genes. The mRNA of inflammation-related cytokines was examined by real-time PCR, and the expression of the cytokines in hPDLFs detected by cytokine flowcytomix assay.

RESULTSThe relative expression of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, TNF-β and interferon (IFN)-γ mRNA in the hPDLFs with 24 h persistent-pressure (0.3633 ± 0.0874, 0.4200 ± 0.0285, 0.1697 ± 0.0284, 0.0983 ± 0.0131, 0.2840 ± 0.0676 and 3.1067 ± 0.2857) was significantly higher than the group without mechanical force (0.1173 ± 0.0176, 0.1691 ± 0.0174, 0.0117 ± 0.0021, 0.0243 ± 0.0050, 0.0000 ± 0.0000 and 0.1433 ± 0.0125), P < 0.05. The cell culture supernatant cytokines expression of IL-1β, IL-6, IL-8, TNF-α, TNF-β and IFN-γ after 48 h cultured [(18.21 ± 1.01), (1634.11 ± 472.41), (1461.47 ± 50.53), (20.71 ± 2.52), (884.11 ± 118.86) and (1461.47 ± 333.37) ng/L] was significantly higher than the group without mechanical force [(5.32 ± 4.97), (373.56 ± 155.92), (679.11 ± 141.42), (4.32 ± 0.73), (3.56 ± 0.92) and (204.11 ± 35.36) ng/L], P < 0.05. The relative mRNA and protein expression of IL-2, IL-4, IL-5, IL-10 and IL-12 showed no significant difference between the both groups.

CONCLUSIONSPersistent static mechanical force could regulate the expression of some inflammation-related cytokines. These up-regulated cytokines may be invloved in remodeling of hPDLFs, bone resorption and periodontal microenvironment.