Mechanical stress induces expression of cytokines in human periodontal ligament cells.
OBJECTIVE
Periodontal tissue has a unique structure in that the human periodontal ligament (hPDL) lies between the hard tissues of cementum and alveolar bone. Although the role of cytokines in hPDL function is not clearly understood, we investigated the effect of mechanical stress as hydrostatic pressure (HP) on cytokine expression in hPDL cells.


METHODS
The hPDL cells were obtained from a healthy maxillary third molar. After the third to fourth passage, the cells were exposed to HP ranging from 1 to 6 MPa as previously described. Total RNA was extracted and the expression of cytokine mRNA was determined by RT-PCR.


RESULTS
The exposure to 6 MPa of HP caused no morphological changes of hPDL cells, and did not affect the cellular viability. No expression of IL-1beta, IL-6, IL-8, TNF-alpha, receptor activator of NF-lambdaB (RANK), receptor activator of NF-lambdaB ligand (RANKL), or osteoprotegerin mRNA was observed in the control cells under atmospheric pressure, whereas, in hPDL cells treated with HP, a pressure-dependent enhancement of IL-6, IL-8, RANKL, and OPG mRNA expression was observed between 10 and 60 min after the exposure to HP.


CONCLUSIONS
These results suggest that hPDL cells may play a role in the production of cytokines in response to mechanical stress in vivo.
Department of Dental Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan. yamamoto@koto.kpu-m.ac.jp
T
T
Yamamoto
M
M
Kita
I
I
Kimura
F
F
Oseko
R
R
Terauchi
K
K
Takahashi
T
T
Kubo
N
N
Kanamura
D000328:Adult; D001274:Atmospheric Pressure; D002352:Carrier Proteins / Q000032:analysis; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D016207:Cytokines / Q000032:analysis*; D005260:Female; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D006874:Hydrostatic Pressure; D007375:Interleukin-1 / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D016209:Interleukin-8 / Q000032:analysis; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis; D053244:Osteoprotegerin; D010513:Periodontal Ligament / Q000166:cytology / Q000276:immunology*; D053245:RANK Ligand; D012313:RNA / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis; D013314:Stress, Mechanical; D013997:Time Factors; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D002352:Carrier Proteins; D016207:Cytokines; D006023:Glycoproteins; D007375:Interleukin-1; D015850:Interleukin-6; D016209:Interleukin-8; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; D014409:Tumor Necrosis Factor-alpha; D012313:RNA