Expression of Antigen Presenting Function-Associated Surface Molecules on Interferon gamma-Treated Gingival Fibroblasts and Periodontal Ligament Fibroblasts / 대한치주과학회지

It is becoming increasingly clear that human gingival fibroblasts(HGF) may play a role in regulating immune responsiveness in inflammatory periodontal lesions. Stimulation of HGF with locally-secreted T cell cytokine IFNgamma induces human leukocyte antigen class II(HLA II) expression on HGF, which is one of the characteristic feature of professional antigen presenting cells(pAPC). However, IFNgamma-treated HGF and other nonprofessional antigen presenting cells(npAPC) are known to be ineffective or less effective antigen presenter to resting T cells. This study, therefore, was undertaken in an effort to elucidate the differences in expression of cell surface molecules between npAPC in periodontal tissues, such as HGF and periodontal ligament fibroblasts(PDLF), and pAPC such as monocytes/macrophages. Using flow cytometry, the levels of cell surface expression of HLA-D, ICAM-1, LFA-3, and B7-1, which are involved in antigen presentation, were determined in HGF, PDLF and human myelomonocytic cell line THP-1. IFNgamma clearly induced HLA-D expression on both of fibroblasts and monocytes dose dependently. However, expression level on monocytes were 4 to 5 times higher than that on fibroblasts, and induction rate was faster in monocytes than in fibroblasts. The levels of ICAM-1 expression on fibroblasts and monocytes were enhanced by IFNgamma in a dose dependent manner. On the other hand, the expression of LFA-3 molecule, which could be detected in fibroblasts and monocytes without cytokine stimulation, was no more enhanced by addition of IFNgamma. B7-1, important costimulatory molecule in T cell activation and proliferation, was not detected on both of fibroblasts and monocytes even when stimulated with IFNgamma, except on monocytes fully differentiated by pretreatment of PMA and treated by IFNgamma. These results suggest that delayed expression of HLA-D and absence of B7-1 on IFNgamma -treated fibroblasts may at least in part be involved in the ineffectiveness of fibroblasts as primary APC. And it is postulated that although periodontal fibroblasts may not serve as primary APC in normal periodontium, sustained expression of HLA II on ubiquitous fibroblasts in inflammatory lesions may perpetuate immune responses and produce chronic inflammation and tissue injury.

A Study on the Loss of Tooth Substance and Surface Changes following Root Planing / 대한치주과학회지

The purpose of this study was to evaluate in vitro effects of the loss of tooth substance and root surface changes following root planing with various periodontal instruments. The 39 extracted human teeth due to severe periodontal disease were included. The total 50 root surfaces of 30 teeth were root planed with following instruments : Group 1, with Gracey curette, Group 2, with ultrasonic scaler, Group 3, with rotating root planing bur, Group 4, with Gracey curette plus rubber cup polishing, and Group 5, with ultrasonic scaler plus rubber cup polishing. Following root planing, the amount of tooth substance loss was evaluated by measuring the weight of the removed tooth substance and then 5 specimens (5x5x2mm) were randomly selected from the each group for roughness measurement. Root planed areas of each specimen were subjected to five measurements using the Profilometer and an average surface roughness values(Ra) for each group was obtained. Statistical difference for roughness values of each group was analyzed using oneway ANOVA and student t-test. For scanning electron microscopic(SEM) examination of root surface changes following root planing, 15 root surfaces of remaining 9 teeth were root planed and 3 specimens were randomly selected. The mean loss of tooth substance removed was Group 1, 7.0+/-1.09mg, Group 2, 1.3+/-1.00mg, Group 3, 5.8+/-1.72mg, Group 4, 8.7+/-1.34mg, and Group 5, 4.5+/-1.68mg following root palning, respectively. These results indicate that curette is effective instrument in the respect of diseased root substance removal. The average surface roughness values are following results : Group 1 and Group 4 were the smoothest surface (Ra=0.34+/-0.06micrometer, Ra=0.34+/-0.04micrometer, respectively) and Group 2 was the roughest surface (Ra=2.09+/-0.06micrometer). Statistical analysis of roughness values demonstrated a highly significant difference (P<0.05) between each experimental groups. However, no statistically significant difference in roughness values were observed between the Group 1 and Group 4. The results in this study suggest that curette and/or polishing procedure should be done after root planing with ultrasonic scaler and caution should be used with diamond-coated bur during routine root planing procedure.

Effects of Substance P on the Release of Cytokines from Immune Cell Lines / 대한치주과학회지

The neuropeptide substance P(SP) has been implicated in the mediation of inflammation and immune-mediated disease such as arthritis. Recently, it was reported that SP was markedly increased around the blood vessels in inflamed gingiva as well as in close association with the inflammatory cell infiltrate. These results support that SP may contribute to the pathophysiology of neuronal inflammation in human periodontal tissues. SP may regulate inflammatory/immune responses by stimulating the proliferation of human T cells, differentiation and antibody-secreting potential of B cells, macrophage respiratory burst, connective tissue proliferation, and the secretion of cytokines from monocytes and T cells. Here, I studied potential role of SP as a costimulatory chemical signal in inflammatory/immune responses, by determining the released proinflammatory cytokines such as MIP-1alpha, IL-1beta, and IL-6 from culture supernatants of homogeneous immune cell lines. Serum free cell supernatants were concentrated with TCA precipitation, fractionated with SDS-PAGE, and subjected into western blot analysis. Among 15 cell lines tested, macrophage/monocyte cell line RAW264.7 and WR19m.1 showed the highest level of induction of MIP-1alphawhen stimulated with LPS. Discrete IL-6 bands with multiple forms of molecular mass were detected from supernatants of B cell lines A20(32kDa), Daudi(32, 35kDa), and SKW6.4(29kDa), which were expressed constitutively. IL-1beta could not be detected by the method of western blot analysis from supernatants of all cell lines tested except RAW264.7, WR19m.1, and erythroid cell line K562 which showed the least amount of IL-1betasecretion. SP 10(-9)M with suboptimal dose of LPS treatment showed synergistic induction of MIP-1alpharelease from RAW264.7 or WR19m.1, and also IL-6 release from A20, but this synergism is not the case in costimulation of RAW264.7 or WR19m.1 with SP 10(-9)M and TPA. Although treatment of T cell line CTLL-R8 with SP 10(-7)M or PHA+TPA induced modest level of MIP-1alpha secretion, synergism was not observed when they are applied together. These findings all together suggest the possibility of a regulatory role of SP in inflammatory/immune reaction through differential modulation of bioactivities of other chemical cosignals.

The Effects of Nd:YAG Laser Irradiation on the Root Surface: A Scanning Electron Microscopic Study / 대한치주과학회지

The purpose of this study was to evaluate the in vitro effects of Nd:YAG laser irradiation on removal of a root surface smear layer after root planing in comparison with Tetracycline HCl. The 60 extracted human teeth due to severe periodontal disease were vigorously scaled and root planed with Gracey curet. Thirty specimen(5x5x2mm) were obtained from root planed surface of 30 human teeth and assigned randomly to one of three groups : root planed group(5 specimen), Tetracycline HCl group(5 specimen, burnished for 5 minutes), and Nd:YAG laser group(25 specimen, German Dental Laser, Fotona Twinlight). Nd:YAG laser group was divided into 4 subgroups according to power of 1W, 1.5W, 2W, 3W at frequency to 10Hz. The specimen were then fixed, and examed by Scanning electron microscopic study. 30 of 60 human teeth used to measurement of the intrapulpal temperature rise during laser irradiation. Laser-irradiated surface exhibited various surface texture from relative flat surface to irregular surface with patent dentinal tubules of various shape and size. In some area, the root surface alteration which are carbonization, pit and crater formation and melting and resolidification were observed. The number of exposed dentinal tubules per unit(100micrometer2) on tetracycline HCl group was more than that in the laser group below 1.5W of power(150mJ/pulse) and was significantly less than that in laser group above 2W of power(200mJ/pulse)(P<0.001). As power increased the intrapulpal temperature rise also increased. The result suggested that the parameter which effectively remove root surface smear layer than tetracycline HCl may cause thermal damage to pulp and root surface alteration result from laser exposure would indicate need for additional instrumentation. Thus, Nd:YAG laser irradiation in these parameter may not be appropriate for clinical use as adjunct to conventional periodontal therapy