Expression of Heat Shock Protein 70 in the Periodontal Ligament During Orthodontic Tooth Movement

Evaluation of heat shock protein 70 and toll-like receptor 4 expression in gingival crevicular fluid in response to orthodontic forces

OBJECTIVES

The aim of this study was to assess the concentrations of heat shock protein 70 (HSP70) and toll-like receptor 4 (TLR4) during orthodontic tooth movement and to compare their levels with interleukin-1β (IL-1β), a well-known proinflammatory biomarker.

MATERIALS AND METHODS

This study consisted of 20 patients (8 males, 12 females; mean age 14.75 ± 2.34 years) who needed maxillary premolar extraction and segmental canine distalization. Concentrations of HSP70, TLR4, and IL-1β were examined before extraction (T1), at the 1st (T2), 4th (T3), 7th (T4), 14th (T5), and 30th (T6) days of canine retraction by enzyme-linked immunosorbent assay analysis of gingival crevicular fluid samples. Statistical analyses were performed with repeated measure ANOVA and Spearman's rank correlation coefficient analysis (p < 0.05).

RESULTS

HSP70 increased gradually from T1 to T6 and showed significant differences between T1-T6 and T2-T6 (T1:3.28 ± 0.92 ng/ml; T2:3.72 ± 0.66 ng/ml; T6:9.35 ± 2.45 ng/ml). The lowest TLR4 concentration was at T1, peaked at T3 and remained constant afterwards with significant differences between T1-T3, T1-T4, and T1-T6 (T1:0.71 ± 0.02 pg/ml; T3:1.04 ± 0.11 pg/ml; T4:0.95 ± 0.06 pg/ml; T6:1.00 ± 0.07 pg/ml). IL-1β increased from T1 to T6 with significant differences between T1-T4, T1-T5, and T1-T6 (T1:55.71 ± 5.48 pg/ml; T4:100.11 ± 16.92 pg/ml; T5:103.71 ± 23.19 pg/ml; T6:125.12 ± 22.04 pg/ml). The increase in HSP70 and TLR4 from T2-T3 showed a significant correlation (r = 0.598; p = 0.005).

CONCLUSIONS

The increased levels of HSP70, TLR4, and IL-1β show the contribution of these mediators to the inflammatory response from the early stages of orthodontic tooth movement.

CLINICAL RELEVANCE

The regulation of HSP70, TLR4, and/or IL-1β secretion during orthodontic force application could provide alterations for desired optimal tooth movement.

Heat shock protein 70 and the extent of nuclear damage in periodontal ligament compression side cells with orthodontic force application - An ex-vivo evaluation

OBJECTIVE

Increased levels of heat shock proteins after several types of stress play a central role in cellular homeostasis allowing for continued cell survival. This study was aimed at quantitatively analysing the expression pattern of major damage associated molecular patterns (DAMPs) - HSP70, and the amount of nuclear damage incident in periodontal ligament compression side cells.

MATERIAL AND METHODS

Sixteen subjects with bimaxillary dentoalveolar protrusion requiring extraction of all first premolars as part of orthodontic treatment were selected. Extractions were carried out pretreatment from control group. In the experimental group, a buccally directed spring, with force range of 70-120gms promoting bodily movement of maxillary first premolars was placed. Periodontal ligament was scraped from the middle third of the root from the compression side, the cells were isolated and cultured followed by HSP70 protein estimation with western blot analysis and the extend of nuclear damage was assessed with COMET assay.

RESULTS

Western Blot analysis of HSP70 revealed a statistically significant increased expression of HSP70 (P<0.05; CI=95%) in the force applied group compared with the control group. COMET assay could demonstrate significant amount of nuclear fragmentation in the compression side periodontal ligament cells in comparison to control group (P<0.05; CI=95%).

CONCLUSIONS

All these findings demonstrated, for the first time, that orthodontic force application augments release of HSP70 from periodontal ligament cells as a measure to restore tissue homeostasis. Further the study demonstrated that orthodontic forces induce DNA fragmentation, which is quantified more than double the amount observed in the control group.

HSP70 mRNA expression by cells of the epithelial rest of Malassez due to mechanical forces in vitro

Background

The purpose of the present study was to examine the in vitro responses of ERM cells under the combination of centrifugal and compression forces, in terms of their expression of HSP70 mRNA.

Methods

The ERM cells were positive for CK19 indicating that they were derived from the odontogenic epithelium. Cultured ERM cells were applied centrifugal force and compressing force at one to three times as mechanical forces. After addition of forces, cells were observed using scanning electron microscope (SEM) and were measured expression of HSP70 mRNA by RT-PCR.

Results

SEM observations showed the cells were flattened immediately after the application of mechanical force, but nuclear protrusions recovered the same as the control 3 h later. A significantly higher expression of HSP70 mRNA was observed in ERM cells under mechanical force compared with the control, but it gradually decreased with time. No accumulation of HSP70 mRNA expression occurred with intermittent force. However, the expression of HSP70 mRNA with intermittent force repeated 3 times was significantly higher compared with intermittent force applied only once or twice.

Conclusions

These findings suggest that ERM cells express HSP70 mRNA in response to mechanical force, and that intermittent force maintains the level of HSP70 mRNA expression.