Increased Expression of Vascular Endothelial Growth Factor in Cyclosporin A-Induced Gingival Overgrowth in Rats

The Effect of Cyclosporin A on Alveolar Bone in Rats Subjected to Experimental Periodontal Disease

Cyclosporine A (CsA), broadly used in organ transplantation, may contribute to pathogenesis of osteoporosis. The aim of this study was to investigate the effects of CsA on alveolar bone in rats subjected or not to experimental periodontal disease using biochemical, radiographic, and histometric analysis. Forty Wistar rats were divided into 4 equal groups: Group I (Control), Group II (CsA was injected subcutaneously in a daily dose of 10 mg/kg), Group III (Ligature was placed around the mandibular molars), Group IV (Ligature+CsA). After 60 days, rats were decapitated, serum alkaline phosphatase and calcium levels were measured. Radiographic-alveolar bone loss (ABL), histometric-ABL, and percentage of new alveolar bone formation (NABF%) were determined on mandibular molars. Significant increase in serum alkaline phosphatase levels ( p < 0.001), no significant difference in calcium levels were observed ( p > 0.05) in Group IV compared to Group III. Radiographic and histometric-ABL were significantly less ( p < 0.001), NABF% was significantly greater ( p < 0.05) in Group IV than in Group III. No significant difference in any of the parameters between Group II and Group I was found. It can be concluded that in the presence of periodontal disease, CsA treatment may bring out an imbalance in the alveolar bone homeostasis by decreasing resorption and stimulating formation of alveolar bone in rats.

Fibroblast VEGF-receptor 1 expression as molecular target in periodontitis

AIM

Degradation of extracellular matrices is an integral part in periodontitis. For antagonizing this pathophysiological mechanism, we aimed at identifying gene expression profiles in disease progression contributing periodontitis-associated fibroblasts (PAFs) versus normal gingival fibroblasts to determine their molecular repertoire, and exploit it for therapeutic intervention.

MATERIALS AND METHODS

Applying an exploratory analysis using a small number of microarrays in combination with a three dimensional (3D) in vitro culture model that incorporates some aspects of periodontitis, PAFs were initially characterized by gene-expression analyses, followed by targeted gene down-regulation and pharmacological intervention in vitro. Further, immunohistochemistry was applied for phosphorylation analyses in tissue specimens.

RESULTS

PAFs were characterized by 42 genes being commonly up-regulated >1.5-fold, and by five genes that were concordantly down-regulated (<0.7-fold). Expression of vascular endothelial growth factor (VEGF)-receptor 1 (Flt-1) was highly enhanced, and was thus further explored in in vitro culture models of periodontal fibroblasts without accounting for the microbiome. Phosphorylation of the VEGF-receptor 1 was enhanced in PAFs. Receptor inhibition by a specific VEGF-receptor inhibitor or intrinsic down-regulation by RNAi of the VEGF-receptor kinase in 3D gel cultures resulted in significant reduction in collagen degradation associated with increased tissue inhibitor of metalloproteinase expression, suggesting that Flt-1 may contribute to periodontitis.

CONCLUSION

Based on the finding that VEGF-receptor kinase inhibition impaired collagen degradation pathways, Flt-1 may represent a candidate for therapeutic approaches in periodontitis.

Vascular endothelial growth factor levels in gingival crevicular fluid before and after periodontal therapy

INTRODUCTION

Of the various cytokines and growth factors regulating angiogenesis, the most potent agent acting on vascular endothelium is vascular endothelial growth factor(VEGF). The present study aims to access VEGF concentration in periodontal diseases and the effect of periodontal therapy on its concentration in gingival crevicular fluid (GCF).

MATERIALS AND METHODS

Ninety five subjects (47 females and 48 males) 25- 47 y of age were divided into healthy (group-1), gingivitis (group-2), and periodontitis (group-3). GCF samples were collected using micro-capillary pipettes & were transferred immediately to plastic vials and stored at -70˚C until the time of the assay. The concentration of VEGF was determined using commercially available ELISA kit.

RESULTS

The mean VEGF concentration was highest in periodontitis patients (Group 3) (88.08±8.04pg/ml), with lowest in healthy patients (Group 1). VEGF levels reduced significantly after therapy in Groups 2 and 3.

CONCLUSION

VEGF levels in GCF had a significant correlation with both periodontal disease progression and healing after therapy.

Effect of adjunctive roxithromycin therapy on interleukin-1β, transforming growth factor-β1 and vascular endothelial growth factor in gingival crevicular fluid of cyclosporine A-treated patients with gingival overgrowth

BACKGROUND AND OBJECTIVE

Systemic macrolide antibiotic administration has been shown to result in the elimination or reduction cyclosporine A-induced gingival overgrowth. Roxithromycin (ROX) is known to have anti-inflammatory, immunomodulatory and tissue reparative effects. This study was to evaluate the effect of adjunctive ROX therapy on cyclosporine A-induced gingival overgrowth and interleukin (IL)-1β, transforming growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF) levels in gingival crevicular fluid of renal transplant patients.

MATERIAL AND METHODS

Thirty-one patients with clinically significant overgrowth and 16 periodontally healthy subjects were included in this randomized, double-blind, placebo-controlled, parallel-arm study. Patients received scaling and root planing (SRP) at baseline and randomized to take either ROX or placebo for 5 d. The clinical parameters, including plaque index, papillary bleeding index, probing depth and gingival overgrowth scores, were recorded. The amounts of IL-1β, TGF-β1 and VEGF in gingival crevicular fluid were detected by ELISA. Periodontal parameters as well as gingival crevicular fluid biomarker levels were evaluated at baseline and at 1 and 4 wk post-therapy.

RESULTS

Following SRP plus ROX and SRP plus placebo therapy, significant improvements in clinical periodontal parameters of both study groups were observed (p < 0.025). In the ROX group, adjunctive ROX therapy resulted in a greater gingival overgrowth scores reduction compared with those in the placebo group at 4 wk (p < 0.017). Initial amounts of IL-1β, TGF-β1 and VEGF for both the ROX and placebo groups were significantly higher than those for healthy subjects (p < 0.017), with no statistical difference between the two study groups. At 1 and 4 wk post-therapy, significant decreases in the amounts of IL-1β, TGF-β1 and VEGF were observed in both study groups when compared with baseline (p < 0.025), but there was no difference in the levels of IL-1β and VEGF between the two study groups. The amount of decrease in TGF-β1 levels for the ROX group was statistically significant compared to that for the placebo group at 4 wk after treatment (p < 0.017).

CONCLUSION

Our study indicated that combination of ROX with non-surgical therapy improves gingival overgrowth status and decreases gingival crevicular fluid TGF-β1 levels in patients with severe gingival overgrowth. The reduction of gingival crevicular fluid TGF-β1 following ROX therapy suggests an anti-inflammatory/immunomodulatory effect of ROX on the treatment of cyclosporine A-induced gingival overgrowth.

Effects of tacrolimus and nifedipine, alone or in combination, on gingival tissues

BACKGROUND

The aim of this study is to compare gingival changes induced by short- and long-term tacrolimus and nifedipine administration, alone or in combination, and evaluate the expression levels of tumor suppressor phosphatase and tensin homolog (PTEN) in drug-induced gingival overgrowth.

METHODS

Eighty rats were equally divided into eight groups: 1) tacrolimus for 8 weeks; 2) nifedipine for 8 weeks; 3) tacrolimus and nifedipine for 8 weeks; 4) 8-week control; 5) tacrolimus for 24 weeks; 6) nifedipine for 24 weeks; 7) tacrolimus and nifedipine for 24 weeks; and 8) 24-week control. Histomorphometric analyses included measurements of epithelial thickness, connective tissue thickness, and height. Stereologic analyses included measurements of volumetric densities of fibroblasts (Vf), collagen fibers (Vcf), and blood vessels (Vbv). In addition, PTEN expression was analyzed using immunohistochemistry.

RESULTS

Epithelial thickness and connective tissue thickness were significantly increased in groups 5, 6, and 7 compared to group 8 (P <0.05), whereas connective tissue height was significantly increased in groups 5 and 7 (P <0.001). Vf and Vcf were significantly increased in group 7 compared to group 8 (P <0.001). PTEN immunoreactivity was significantly decreased in all experimental groups compared to the control groups (P <0.05).

CONCLUSIONS

Results suggest that duration of drug administration is a more important risk factor than drug combination. The results include a potentially new insight about PTEN's role in the etiology of drug-induced gingival overgrowth.

Biochemical analysis of pentraxin 3 and fibrinogen levels in experimental periodontitis model

Objective. Pentraxin 3 (PTX3), newly discovered inflammation marker, is a member of acute-phase proteins. The hypothesis, synthesis of gingival tissue and serum PTX-3 increases in the experimental periodontitis model (with 10-day and 40-day periods), was tested by detecting gingival tissue and serum PTX-3 levels in rats with experimental periodontitis. Methods. Thirty rats were randomly divided into three groups of ten animals each: ligature-induced experimental periodontitis groups (with 10-day (Group1) and 40-day periods (Group2)) and healthy group (Group3). At the end of experimental period, rats were sacrificed, and radiological and histomorphometric analyses were performed on the mandibles. PTX3 levels were measured in gingival tissue and serum samples using ELISA. Plasma fibrinogen levels were measured according to the nephelometric method. Results. Significant alveolar bone resorption and periodontal inflammation were evident in periodontitis groups. Levels of PTX3 in gingival tissue were statistically higher in Group 1 than those in groups 2 and 3 (P < 0.01). No significant difference was found in serum PTX3 levels between experimental periodontitis and control groups (P > 0.05). Plasma fibrinogen levels were significantly increased in the experimental periodontitis groups (P < 0.001). Conclusion. PTX3 seems to be associated with tissue destruction in earlier periods of inflammatory periodontal disease, contrary to the fibrinogen findings.

Cardioprotective effect of calcineurin inhibition in an animal model of renal disease

AIMS

Chronic kidney disease is directly associated with cardiovascular complications. Heart remodelling, including fibrosis, hypertrophy, and decreased vascularization, is frequently present in renal diseases. Our objective was to investigate the impact of calcineurin inhibitors (CNI) on cardiac remodelling and function in a rat model of renal disease.

METHODS AND RESULTS

Male Sprague Dawley rats were divided into six groups: sham-operated rats, 5/6 nephrectomized rats (Nx) treated with vehicle, CNI (cyclosporine A 5.0 or 7.5, or tacrolimus 0.5 mg/kg/day) or hydralazine (20 mg/kg twice a day) for 14 days, starting on the day of surgery. Creatinine clearance was significantly lower and blood pressure significantly higher in Nx rats when compared with controls. Morphological and echocardiographic analyses revealed increased left ventricular hypertrophy and decreased number of capillaries in Nx rats. Treatment with CNI affected neither the renal function nor the blood pressure, but prevented the development of cardiac hypertrophy and improved vascularization. In addition, regional blood volume improved as confirmed by contrast agent-based echocardiography. Hydralazine treatment did not avoid heart remodelling in this model. Gene expression analysis verified a decrease in hypertrophic genes in the heart of CNI-treated rats, while pro-angiogenic and stem cell-related genes were upregulated. Moreover, mobilization of stem/progenitor cells was increased through manipulation of the CD26/SDF-1 system.

CONCLUSION

We conclude from our studies that CNI-treatment significantly prevented cardiac remodelling and improved heart function in Nx rats without affecting renal function and blood pressure. This sheds new light on possible therapeutic strategies for renal patients at high cardiovascular risk.

Short-term induction of thrombocytopenia delays periodontal healing in rats with periodontal disease: participation of endostatin and vascular endothelial growth factor

BACKGROUND AND OBJECTIVE

Platelets contain factors, including VEGF and endostatin, that can modulate the healing process. We evaluated the effects of severe thrombocytopenia on periodontal healing in rats and determined the contribution of VEGF and endostatin to the healing process.

MATERIAL AND METHODS

Rats were distributed into three test groups and two control groups. Cotton ligatures were placed at the gingival margin level of the lower first molar in the test groups. Sham-operated rats and rats in one of the periodontitis groups were killed 15 days later. Rats in the remaining two periodontitis groups had the ligatures removed in order to study the spontaneous recovery from the periodontal disease 15 days later, and these rats were treated with rabbit antiplatelet serum, in order to induce thrombocytopenia, or normal rabbit serum. An additional group without ligatures received antiplatet serum in the same period.

RESULTS

After ligature removal, rats treated with normal rabbit serum showed reduced myeloperoxidase activity, decreased alveolar bone loss and increased numbers of blood vessels. Thrombocytopenia caused a delay in alveolar bone regeneration, a decrease in the number of vessels and a modest decrease in myeloperoxidase activity. In the rats with periodontitis, serum endostatin concentrations were slightly decreased and serum VEGF remained unchanged compared with sham-operated animals. After ligature removal, a significant VEGF increase and endostatin decrease were observed in the rats treated with normal rabbit serum. Thrombocytopenia led to a dramatic fall in both VEGF and endostatin concentrations.

CONCLUSION

Thrombocytopenia leads to a delay of periodontal healing in the situation of experimental periodontitis, which might be mediated in part by a decrease in the serum concentration of VEGF and endostatin derived from the platelets. However, other factors derived from the platelets may also have contributed to a delay of periodontal healing in the rats with thrombocytopenia.

Differential gene and protein expression of tissue inhibitors of metalloproteinases (TIMP)-3 and TIMP-4 in gingival tissues from drug induced gingival overgrowth

OBJECTIVES

The purpose of this study was to analyse mRNA expression and protein localization of tissue inhibitors of metalloproteinases (TIMP)-3 and TIMP-4 in gingival tissues removed from drug (calcium-channel blocker) induced gingival overgrowth and periodontitis patients.

DESIGN

Employing RT-PCR, we evaluated TIMP-3 and TIMP-4 mRNA levels of 20 human gingival tissue samples taken from patients suffering gingival overgrowth (GO) and periodontitis (P). Then, using immunohistochemistry we investigated the TIMP-3 and TIMP-4 protein localization of five sample tissues from each group.

RESULTS

TIMP-4 mRNA levels in GO-gingiva tended to be lower than in P-gingiva but the results differed little (p = 0.22). Varying degrees of inflammation in the protein localization of TIMP-3 and TIMP-4 were found. TIMP-4 immunoreactivity (IR) was weak in the endothelial cells, fibroblasts, epithelial basal and parabasal cells while the degree of inflammation differed as well. TIMP-3 and TIMP-4 IR in inflammatory cells, including lymphocytes, plasma cells, and macrophages, were faint and intense respectively. For P-gingiva, both TIMP-3 and TIMP-4 IR expression was weak in the endothelial cells, fibroblasts, basal and parabasal epithelial layers. Expression of TIMP-3 was faint in the inflammatory cells, whereas TIMP-4 IR was strong.

CONCLUSION

Our findings suggest that TIMP-3 and TIMP-4 expression differs in GO and P-gingival tissues, both of which are potentially involved in pathogenesis.

The Expression of Vascular Endothelial Growth Factor in a Rat Model at Destruction and Healing Stages of Periodontal Disease

BACKGROUND

The major role of vascular endothelial growth factor (VEGF), an angiogenic mediator, in promoting the progression or the healing of periodontal disease is still unclear. The aim of this study was to evaluate the VEGF expression in the destruction and healing stages of periodontal disease and to investigate the association between VEGF expression and vascularization with regard to the number and diameters of blood vessels.

METHODS

Thirty rats were distributed equally into two test groups and a control group. Experimental periodontal disease was induced in the test groups by silk ligatures, which were kept in position for 40 days. On the 40th day, ligatures were removed from the healing group, whereas ligatures were left in position in the destruction group. On the 60th day, rats were sacrificed; histomorphometric and biochemical analyses were carried out to determine the number and diameters of blood vessels and the assessment of VEGF concentration by enzyme-linked immunosorbent assay, respectively.

RESULTS

There was a statistically significant increase in the number of blood vessels in the healing group and in the diameters of blood vessels in the destruction group compared to the control group (P <0.001). In vivo VEGF expressions were highest in the healing group (P <0.001) and correlated significantly with the number of blood vessels (r(2) = 0.814; P = 0.001).

CONCLUSION

VEGF expression may be related more to the healing stage of periodontal disease than to the destruction stage of the lesion.

Levels of gingival tissue platelet activating factor after conventional and regenerative periodontal surgery

The hypothesis, a relationship between gingival tissue platelet activating factor (PAF) levels and healing after periodontal surgery, was tested by measuring PAF levels in gingival tissues collected from sites that had undergone flap surgery and guided tissue regeneration (GTR) or flap surgery alone. Using a split-mouth design, 20 intrabony defects were randomly assigned to treatment with flap surgery and GTR (group 1) or with flap surgery alone (group 2). Gingival tissue samples were obtained at surgery (baseline) and at 6-month follow-up evaluation visit. One half of each sample was used for analysis of PAF levels by high-performance liquid chromatography, and the other half of the sample was used for histomorphometric analysis that included measurements of number and diameter of blood vessels. PAF levels and diameter of blood vessels were significantly decreased (p < 0.01), and the number of blood vessels was significantly increased (p < 0.05) in both groups after 6 months compared to the baseline values. Postoperative number of blood vessels were significantly higher in group 1 (p < 0.05), whereas there was no significant difference in postoperative PAF levels between the two groups (p > 0.05). Based on the reported results, it is suggested that a decrease in gingival PAF levels might be found after conventional and regenerative periodontal surgery.

Comparison of the proliferative activity in gingival epithelium after surgical treatments of intrabony defects with bioactive glass and bioabsorbable membrane

Guided tissue regeneration is based on preventing the more rapidly proliferating epithelium from growing into the periodontal defect after surgical procedures incorporating barrier membranes. The aim of this study was to compare the proliferative activity of gingival epithelium using proliferating cell nuclear antigen (PCNA) as a marker of cell proliferation after surgical treatments with bioactive glass graft material and bioabsorbable membrane. Using split mouth design, 20 intrabony defects were randomly assigned treatments with bioactive glass (BG group) or bioabsorbable membrane (BM group). Gingival biopsies were taken at preoperative and postoperative 12 weeks. After histological processing, the number of the inflammatory cells was measured in hematoxylin and eosin-stained sections; PCNA expression was determined in immunohistochemically-stained sections. At postoperative 12 weeks, the number of the inflammatory cells was significantly decreased (p < 0.01), PCNA expression was significantly increased (p < 0.001) in both treatment groups compared to baseline data. There was no significant difference in PCNA expression between baseline values of two groups (p > 0.05), while at postoperative 12 weeks, increase in BG group was significantly greater than that in BM group (p < 0.001). These results suggest that epithelial cell proliferation is more prominent after treatment of intrabony defects with bioactive glass compared to the treatment with bioabsorbable membrane.