Hsiao-Pei Tu

Cyclosporine-A inhibits MMP-2 and -9 activities in the presence of Porphyromonas gingivalis lipopolysaccharide: an experiment in human gingival fibroblast and U937 macrophage co-culture.

BACKGROUND AND OBJECTIVE Studies have shown that bacterial plaque and the associated gingival inflammation increase the severity of gingival overgrowth induced by cyclosporine-A (CsA). This in vitro study aimed to evaluate the effect of CsA on the activities of MMPs from the co-culture of human gingival fibroblasts and U937 macrophages in the presence or absence of Porphyromonas gingivalis lipopolysaccharide (LPS). MATERIAL AND METHODS Activities of pro-MMP-2, MMP-2 and pro-MMP-9 in the supernatants of independent cultures and co-cultures were examined by zymography. RT-PCR was selected to evaluate the expression of mRNA for membrane type-1 (MT1) MMP in the co-cultures. RESULTS Activities of MMPs in the co-cultures were significantly greater when compared with any of the independent cultures. Lipopolysaccharide significantly increased the MMP activities in a dose-dependent manner in the co-cultures, whereas CsA inhibited these activities. In the presence of both CsA and LPS, the MMP activities inhibited by CsA could still be observed in the co-cultures. In the individual cultures, in contrast, the CsA-inhibited MMP activities, in the presence of LPS, were minimally detected. The mRNA expression of MT1-MMP was significantly enhanced after LPS treatment; however, this enhancement was inhibited by CsA. CONCLUSION This study demonstrated that, in co-cultures of human gingival fibroblasts and U937 macrophages, CsA could inhibit MMP activities in the presence of P. gingivalis LPS. It might be part of the underlying reason for the persistent overgrowth of gingiva seen when bacterial plaque and local inflammation are present during CsA therapy.

Nrf-2 Regulates Cyclosporine-stimulated HO-1 Expression in Gingiva

Cyclosporine-A (CsA) stimulates heme oxygenase-1 (HO-1) expression in the gingiva, but the regulation and the role of HO-1 in gingival overgrowth are not well-understood. HO-1 is regulated by several transcription factors, such as nuclear factor-κB (NF-κB) and nuclear factor erythroid-2-related factor 2 (Nrf-2). The aim of this study was to examine the role of Nrf-2 in the regulation of CsA-stimulated HO-1 expression in human gingival fibroblasts. Nrf-2 siRNA (siNrf-2), NF-κB, kinase inhibitors, and sulforaphane (SFN) were used to examine the nuclear translocation of Nrf-2 and expression of HO-1 and transforming growth factor-β1 (TGF-β1) in cells. Treatment with siNrf-2, but not with an NF-κB inhibitor, reduced CsA-stimulated HO-1 mRNA expression. ERK inhibition significantly decreased CsA-stimulated Nrf-2 nuclear translocation and HO-1 mRNA expression. Pre-treatment with SFN showed that HO-1 plays a role in attenuating CsA-mediated TGF-β1 expressions. These findings suggest that CsA-stimulated HO-1 expression is mediated through the activation of ERK, and that Nrf-2 plays a protective role against CsA-induced gingival fibrosis by modulating collagen turnover-related genes.

Bifid mandibular canals and the factors associated with their presence: a medical computed tomography evaluation in a Taiwanese population

OBJECTIVES To examine distribution of bifid mandibular canals in a Taiwanese population and to evaluate factors contributing to the phenomenon. MATERIAL AND METHODS Computed tomographic images from 173 subjects (97 females and 76 males) were obtained using a 64-slice multidetector computerized tomography system, and the presence of bifid mandibular canals, as well as their widths and lengths, was examined. Association of length of bifid canals with possible contributing factors, including gender, age, and side of presentation, as well as size of cross-sectional bony area of mandible along the long axis of mandibular canal, was evaluated. RESULTS Bifid mandibular canals, with mean values of 10.1 and 0.9 mm in length and width, were found in 53 (30.6%) of 173 patients and 64 (18.5%) of 346 hemi-mandibles. Bifid canals appeared more frequently and tend to penetrate mandible with greater lengths in males if compared with those in females. When males were compared with females and when mandibles with bifid canals were compared with ones without, the former tend to present with larger bony area at corresponding levels of cross-sectional plane than the later, respectively. By regression analysis, significant association was found between length of bifid canals and gender, side of hemi-mandible, and bony area at mid-zone of mandibular canal. CONCLUSIONS Bifid canals were observed in 30.6% of subjects and 18.5% of hemi-mandibles. Significant association between length of bifid canals and gender, side of hemi-mandible, and cross-sectional bony area of mandible was observed.

Prevalence and location of maxillary sinus septa in the Taiwanese population and relationship to the absence of molars

OBJECTIVES Understanding the septum structure of the sinus is necessary for correct implant placement in the maxilla if sinus encroachment is required. The exact mechanism that controls septum development is unclear, although a role for the irregular pneumatization of the sinus floor following tooth loss has been suggested. The aims of this study were to examine the prevalence and location of sinus septa in the Taiwanese population and to determine whether there is a relationship between the presence of septa and the absence of molars. MATERIALS AND METHODS Using computed tomography (CT) scans of sinuses obtained from 423 subjects (216 women and 207 men, mean age 53.65 years), septum morphology and its correlation with the presence of molars was examined. RESULTS About 30% of subjects (124/423) had sinus septa, corresponding to 20.45% of all sinus segments detected (173/846). Fifty-nine patients had multiple septa, giving a prevalence of septa of 22.93%. Septa were located most frequently in the regions of the first and second molars. The prevalence was not related to tooth loss (edentulous, partially edentulous, or dentate maxillary segments). Logistic regression analysis showed that men were significantly more likely to have septa than were women (OR=1.67; P=0.019). CONCLUSIONS In the 423 Taiwanese subjects tested, the prevalence of septum was 29.31% according to the subjects and 22.93% according to the sinus segments. The most frequent location of septa was in the region of the first and secondary molars. No correlation was observed between the presence of septa and the absence of molars.

Berberine's effect on periodontal tissue degradation by matrix metalloproteinases: an in vitro and in vivo experiment.

Periodontal disease involves tissue destruction caused by interactions among bacterial antigens and inflammatory mediators including matrix metalloproteinases (MMPs). Berberine, an isoquinoline alkaloid isolated from medicinal herbs, can inhibit the degradative action of extracellular MMPs. The effect of berberine on the periodontal expression of MMPs was examined in vitro and in vivo. Gelatinolytic activity of pro-MMP-2, MMP-2, and MMP-9 in the human gingival fibroblast and/or U-937 was compared after treatment with Porphyromonas gingivalis lipopolysaccharide (P.g. LPS) in four medias containing 0, 1, 10 and 100μM of berberine each. Twelve animals were divided into three groups for the study: (A) non-ligation, (B) ligation, and (C) ligation-plus-berberine (75mg/kg berberine by gastric lavage daily); and the effect of berberine on periodontal destruction was evaluated in the ligature-induced periodontitis in rats for 8 days by micro computerized tomography (micro-CT), histology and immunohistochemistry (IHC). An enhancing effect of P.g. LPS on MMP activities was identified, with a greater effect on fibroblasts/U937 co-culture than on either culture alone. When berberine was added to the LPS-treated cultures, the activities of MMPs were significantly reduced in dose-dependent manner. In the animals, the trends of the following parameters were compared. 1. Micro-CT distances between cemento-enamel junction (CEJ) and dental alveolar bone crest: B>C>A. 2. Histometrically measured crest bone levels: B>C>A. 3. Amount of collagen deposited in tissue areas: A>C>B. 4. Attachment loss: B>C≈A. 5. Connective tissue (CT) attachment: B>either A or C. 6. Expression of cells stained positive for MMP-2 and -9 by IHC: B>C>A. In conclusion, berberine demonstrated in vitro an inhibitory effect on P.g. LPS-enhanced MMP activities of HGF and U937 macrophages, reducing in vivo gingival tissue degradation in periodontitic rats. We thus propose that berberine may slow periodontal degradation through the regulation of MMPs in periodontitis induced by bacterial plaque.

The effects of diallyl sulfide upon Porphyromonas gingivalis lipopolysaccharide stimulated proinflammatory cytokine expressions and nuclear factor-kappa B activation in human gingival fibroblasts.

BACKGROUND AND OBJECTIVE Diallyl sulfide (DAS), a flavor compound from garlic, has varied potential therapeutic activities. Periodontitis is a disease that develops because of host-mediated inflammation to periodontal pathogens. In this study, the effects of DAS on the common proinflammatory cytokines and nuclear factor-kappa B (NF-κB) in human gingival fibroblasts (HGFs) being stimulated with lipopolysaccharide from Porphyromonas gingivalis, a potent periodontal pathogen, were evaluated. MATERIAL AND METHODS Cytotoxicities of DAS and lipopolysaccharide on HGFs were measured with MTS assay. The mRNA and protein expressions of proinflammatory cytokines, including interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, from the HGFs treated with lipopolysaccharide with and without DAS were examined with reverse transcription-polymerase chain reaction and immunocytochemistry, respectively. In addition, the activation and nuclear translocation of NF-κB with and without DAS were compared. RESULTS DAS and lipopolysaccharide treatments within 3 mm and 10 μg/mL, respectively, did not affect the survival rate of HGFs. Lipopolysaccharide (1 μg/mL) significantly increased the mRNA expressions of IL-1β, IL-6 and TNF-α; however, DAS (1 mm) inhibited these expressions. The protein expressions of TNF-α, IL-1β, as well as the NF-κB nuclear translocation were increased after lipopolysaccharide treatment, but decreased when there was a DAS pretreatment. CONCLUSION DAS diminished P. gingivalis lipopolysaccharide-stimulated cytokine expression and NF-κB activation in HGFs; we therefore suggest DAS may be beneficial on periodontal inflammation.

Can chlorhexidine mouthwash twice daily ameliorate cyclosporine-induced gingival overgrowth?

BACKGROUND/PURPOSE Gingival overgrowth can be induced in patients treated with cyclosporine-A (CsA), an immunosuppressant often used following organ transplantation. A pre-existing rat model designed to mimic CsA-induced gingival overgrowth in humans was used to test the effectiveness of frequent application of a chlorhexidine antiplaque solution in reducing the overgrowth. METHODS Four groups of rats were fed CsA. One group received chlorhexidine mouthwash twice a day, the second group received chlorhexidine mouthwash once a day, the third group received chlorhexidine mouthwash every other day, and the fourth group did not receive chlorhexidine mouthwash all. A fifth negative control group received only mineral oil. Overgrowth was determined by measuring the changes in the gingival probing depth and the keratinized gingival width on molars. A gingival histological examination was performed. RESULTS Rats treated with mouthwash twice daily exhibited decreased probing depths and gingival widths without statistical significance. Histological examination revealed that CsA treatment caused gingival enlargement, whereas chlorhexidine treatment twice a day diminished the enlargement. CONCLUSION These findings suggest that chlorhexidine mouthwash used twice daily may reduce the severity of CsA-induced gingival overgrowth. Further research is warranted to determine the optimal dose and treatment regimen.

Up‐regulation of retinoblastoma protein phosphorylation in gingiva after cyclosporine A treatment: an in vivo and in vitro study

BACKGROUND AND OBJECTIVE Cyclosporine A can induce gingival cell proliferation; however, the precise molecular regulation of the proliferation is uncertain. Therefore, this study was carried out to examine, in vivo and in vitro, the expression of genes and proteins associated with gingival cell proliferation after treatment with cyclosporine A. MATERIAL AND METHODS Forty Sprague Dawley rats with right maxillary posterior edentulous gingivae were assigned to a cyclosporine A group (30 mg/kg daily of cyclosporine A, administered orally) or a control group (administered mineral oil only). The animals were killed 4 wk after treatment. The edentulous gingivae were dissected out and analyzed for the expression of proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin-dependent kinase 4 (CDK4) and retinoblastoma protein (Rb1) mRNA and/or protein, and phosphorylated Rb1 (pRb1), by real-time RT-PCR or immunohistochemistry. In human gingival fibroblast (HGF) cultures, the expression of PCNA, CDK4, cyclin D1 and Rb1 proteins and Rb1 phosphorylation were determined by western blotting after cyclosporine A treatment (0-10(4) ng/mL). RESULTS Proliferating cell nuclear antigen and cyclin D1 mRNAs (Pcna and Ccnd1, respectively) were expressed more strongly in the gingivae of cyclosporine A-treated animals than in the gingivae of the controls. Immunohistochemical analyses showed that a greater number of gingival cells stained positive for cyclin D1, CDK4 and pRb1 in the cyclosporine A group than in the control group. Increased expression of cyclin D1, CDK4 and PCNA proteins was observed in HGFs after cyclosporine A treatment. The phosphorylation of Rb1 was enhanced in HGFs after treatment with cyclosporine A at concentrations of 10(2)-10(3) ng/mL. CONCLUSION The increases in cyclin D1, PCNA and CDK4, together with the enhanced phosphorylation of Rb1, suggest that cyclosporine A promotes cell-cycle progression through the G(1)/S transition in the gingiva.

Role of Shh and TGF in cyclosporine-enhanced expression of collagen and α-SMA by gingival fibroblast.

OBJECTIVE Cyclosporine-A (CsA)-induced gingival overgrowth may arise from an alteration in stoma matrix homeostasis. Sonic hedgehog (Shh) plays a key role during embryogenic development and fibrotic progression, and may be involved in CsA-altered gingival matrix homeostasis. METHODS Using the reverse transcription-polymerase chain reaction and Western blot analysis, we investigated the mRNA and protein expressions of Shh, type 1 collagen (COL1), alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta (TGF-β) in human gingival fibroblasts after CsA treatments. The effect of Shh on CsA-induced alterations was further evaluated by the extra-supplement or inhibition of Shh or TGF-β. RESULTS Cyclosporine-A enhanced COL1, α-SMA, Shh and TGF-β expressions in human gingival fibroblasts. The exogenous Shh/TGF-β augmented the expression of COL1 and α-SMA, and the Shh/TGF-β inhibition suppressed the CsA-enhanced COL1 and α-SMA expressions. Moreover, Shh mRNA and protein expressions increased if extra-supplementing the exogenous TGF-β, whereas the CsA-upregulated Shh was mitigated by the TGF-β pathway inhibitor. However, neither exogenous Shh nor the Shh pathway inhibitor alters TGF-β expression or CsA-up-regulated TGF-β expression. CONCLUSIONS Shh, regulated by TGF-β, mediates CsA-altered gingival matrix homeostasis.