Enhancement of receptor-mediated calcium responses by phenytoin through the suppression of calcium excretion in human gingival fibroblasts.

BACKGROUND AND OBJECTIVES: Gingival overgrowth caused by phenytoin is proposed to be associated with Ca2+ signaling; however, the mechanisms that increase the intracellular Ca2+ concentration ([Ca2+ ]i ) are controversial. The current study aimed to elucidate the mechanism underlying the phenytoin-induced increase in [Ca2+ ]i in human gingival fibroblasts (HGFs). METHODS: Effects of 100 µM phenytoin on [Ca2+ ]i in HGFs were examined at the single-cell level using fluorescence images of fura-2 captured by an imaging system consisting of an EM-CCD camera coupled to an inverted fluorescence microscope at room temperature. RESULTS: Exposure of HGFs to 100 µM phenytoin induced a transient increase in [Ca2+ ]i in the absence of extracellular Ca2+ , indicating that the phenytoin-induced increase in [Ca2+ ]i does not require an influx of extracellular Ca2+ . In addition, phenytoin increased [Ca2+ ]i in HGFs depleted of intracellular Ca2+ stores by thapsigargin, indicating that neither Ca2+ release from stores nor inhibition of Ca2+ uptake is involved. Furthermore, the phenytoin-induced [Ca2+ ]i elevation was reduced to 18.8% in the absence of extracellular Na+ , and [Ca2+ ]i elevation upon removal of extracellular Na+ was reduced to 25.9% in the presence of phenytoin. These results imply that phenytoin increases [Ca2+ ]i of HGFs by suppressing the Na+ /Ca2+ exchanger. Suppression of intracellular Ca2+ excretion is thought to enhance the Ca2+ responses induced by various stimuli. Analysis at the single-cell level showed that stimulation with 1 µM ATP or 3 µM histamine increased [Ca2+ ]i in 20-50% of cells, and [Ca2+ ]i increased in many unresponsive cells in the presence of phenytoin. CONCLUSION: Our findings demonstrate that phenytoin induced increase in [Ca2+ ]i by the inhibition of Ca2+ efflux in HGFs. It was also found that phenytoin strongly enhanced small Ca2+ responses induced by stimulation with a low concentration of ATP or histamine by inhibiting Ca2+ efflux. These findings suggest a possibility that phenytoin causes drug-induced gingival overgrowth by interacting with inflammatory bioactive substances in the gingiva.

Treatment of calcium channel blocker-induced gingival overgrowth without modifying medication.

Gingival overgrowth is a common side effect of calcium channel blockers used in the treatment of cardiovascular diseases. While controversial, management includes discontinuing the calcium channel blocker. We report the case of a 66-year-old Japanese man with hypertension and type 2 diabetes mellitus who was diagnosed with severe periodontitis covering almost all the teeth. The patient had been on nifedipine (40 mg/day) and amlodipine (10 mg/day) medication for 5 years. With his physician's consent, nifedipine was discontinued during his treatment for periodontitis, which consisted of oral hygiene instructions and scaling and root planing on all areas. Gingivectomy was performed on the areas of hard fibrous swelling. Nifedipine was resumed during periodontal treatment when the patient's hypertension worsened. His periodontal scores improved when he resumed treatment. We report that significant improvement in gingival overgrowth can occur with basic periodontal treatment, surgery and sustained intensive follow-up without adjusting calcium channel blockers.

Role of IL-6 and STAT3 signaling in dihydropyridine-induced gingival overgrowth fibroblasts.

OBJECTIVES: This study analyzed the role of the interleukin (IL)-6/signal transducer and activator of transcription 3 (STAT3) pathway in dihydropyridine-induced gingival overgrowth (DIGO) fibroblasts. MATERIALS AND METHODS: Tissue samples were obtained through surgical dissection from five DIGO patients and five healthy individuals. Cell cultures were conditioned with nifedipine (Nif) (0.34 µM) and stimulated with IL-1ß (10 ng/ml) to clarify whether IL-6 upregulates extracellular matrix overproduction or has an impact on the cell proliferation rate of DIGO fibroblasts. STAT3 was knocked down using short hairpin (sh)RNA to determine its role in collagen (Col) type I alpha 1 (Colα1(I)) synthesis. RESULTS: Results showed that phosphorylated (p)STAT3 nuclear translocation was activated by a simulated autocrine concentration (50 ng/ml) of IL-6, and application of an anti-IL-6 antibody significantly decreased the pSTAT3/STAT3 ratio in DIGO fibroblasts. STAT3 knockdown significantly decreased STAT3 and Colα1(I) expressions in DIGO cells. DIGO tissues presented stronger proliferating cell nuclear antigen (PCNA) expression than did healthy individuals under the effect of IL-1ß/Nif treatment. CONCLUSIONS: Gingival inflammation (e.g., IL-1ß) and taking dihydropyridine (e.g., Nif) may additively stimulate Col overproduction through the IL-6-STAT3-Colα1(I) cascade in DIGO cells. IL-6-STAT3 signaling may be considered a target for the control of DIGO.

Agrandamiento gingival inducido por fenitoínas / Phenytoin induced gingival enlargement

Se entiende por agrandamiento gingival el incremento en masa y volumen del tejido gingival. Se considera una condición benigna de la cavidad oral, por lo general de manejo rutinario, que logra regularse con medidas simples de control del biofilm microbiano. El agrandamiento gingival puede ser producido por diversas condiciones clínicas, hereditarias, deficiente higiene oral o fármacos. La epilepsia afecta a 1% de la población mundial y requiere el uso de fármacos antiepilépticos o anticonvulsivantes para lograr su control, dentro de éstos la fenitoína actúa como un bloqueador selectivo de los canales de sodio sensibles al voltaje y constituye uno de los fármacos más empleados por su capacidad en el control de crisis focales y generalizadas. La fenitoína se ha relacionado con los agrandamientos gingivales como uno de sus efectos adversos, los cuales se incluyen dentro de las enfermedades por fármaco inducidas en la cavidad oral. El objetivo de este artículo es brindar la información necesaria sobre el manejo correcto de pacientes con agrandamiento gingival producido por fenitoínas y a la vez poder conocer las consecuencias de estos fármacos en la cavidad oral (AU)

Gingival enlargement means the increase in mass and volumen of the gingival tissue. It is considered a benign condition of the oral cavity, usually of routine management, wich can be regulated with simple measures of biofilm control. The gingival enlargement can be produced by diverse clinical conditions, hereditary deficient oral higiene or drugs. Epilepsy affects 1% of the world population and requires the use of antiepileptic or anticonvulsant drugs to achieve its control, within these phenytoin acts as selective blocker or voltage ­ sensitive sodium channels and is one of the most used grugs for its ability to control focal and generalized crises. Phenytoin has been linked to gingival enlargement as one of its adverse effects which is included within the drug diseases induced in the oral cavity. The objective of this article is to provide the necessary information on the correct managment of patients with gingival enlargemen produced by phenytoins and at the same time to know the consequences of these drugs in the oral cavity (AU)

Abordaje Terapéutico de Agrandamiento Gingival Influenciado por Ciclosporina y Nifedipino. Reporte de Caso / Therapeutic Approach of Gingival Enlargement Influenced by Cyclosporine and Nifedipine. Case Report

RESUMEN: Este reporte de caso muestra un paciente atendido en el Postítulo de Periodoncia de la Facultad de Odontología de la Universidad de Chile con diagnóstico de Agrandamiento Gingival influenciado por ciclosporina y nifedipino. El abordaje terapéutico consideró la fase sistémica, la fase higiénica con el tratamiento periodontal no quirúrgico para lograr la eliminación de la infección periodontal antes y después de la fase quirúrgica, y la fase de terapia de soporte periodontal. Se logró así la eliminación de los agrandamientos gingivales influenciados por ciclosporina y nifedipino.

ABSTRACT: This case report shows a patient attended in the Postgraduate Periodontics Program at the Faculty of Dentistry of the University of Chile with a diagnosis of Gingival Enlargement influenced by cyclosporine and nifedipine. The therapeutic approach considered the systemic phase, the hygienic phase with the non-surgical periodontal treatment to achieve the elimination of the periodontal infection before and after the surgical phase, and the phase of periodontal support therapy. Thus, the elimination of gingival enlargements influenced by cyclosporine and nifedipine was achieved.

Galectin-8 mediates fibrogenesis induced by cyclosporine in human gingival fibroblasts.

BACKGROUND AND OBJECTIVE: During cyclosporine-induced gingival overgrowth, the homeostatic balance of gingival connective tissue is disrupted leading to fibrosis. Galectins are glycan-binding proteins that can modulate a variety of cellular processes including fibrosis in several organs. Here, we study the role of galectin-8 (Gal-8) in the response of gingival connective tissue cells to cyclosporine. METHODS: We used human gingival fibroblasts and mouse NIH3T3 cells treated with recombinant Gal-8 and/or cyclosporine for analyzing specific mRNA and protein levels through immunoblot, real-time polymerase chain reaction, ELISA and immunofluorescence, pull-down with Gal-8-Sepharose for Gal-8-to-cell surface glycoprotein interactions, short hairpin RNA for Gal-8 silencing and Student's t test and ANOVA for statistical analysis. RESULTS: Galectin-8 stimulated type I collagen and fibronectin protein levels and potentiated CTGF protein levels in TGF-ß1-stimulated human gingival fibroblasts. Gal-8 interacted with α5ß1-integrin and type II TGF-ß receptor. Gal-8 stimulated fibronectin protein and mRNA levels, and this response was dependent on FAK activity but not Smad2/3 signaling. Cyclosporine and tumor necrosis factor alpha (TNF-α) increased Gal-8 protein levels. Finally, silencing of galectin-8 in NIH3T3 cells abolished cyclosporine-induced fibronectin protein levels. CONCLUSION: Taken together, these results reveal for the first time Gal-8 as a fibrogenic stimulus exerted through ß1-integrin/FAK pathways in human gingival fibroblasts, which can be triggered by cyclosporine. Further studies should explore the involvement of Gal-8 in human gingival tissues and its role in drug-induced gingival overgrowth.

Elevated Interleukin-17A expression in amlodipine-induced gingival overgrowth.

BACKGROUND AND OBJECTIVES: Amlodipine, a calcium channel blocker derivative, is frequently used by patients with high blood pressure. Studies reported that it can induce gingival overgrowth. However, the underlying mechanism is not fully described yet. Interleukin-17A (IL-17A) is known as a proinflammatory cytokine, but current studies indicate that it has a role in fibrotic disorders and epithelial-mesenchymal transition (EMT). The aim of this study was to figure out the possible role of IL-17A in amlodipine-induced gingival overgrowth. MATERIALS AND METHODS: Twenty-nine (29) individuals participated in the study, and they were assigned into 3 groups based on medical status and clinical periodontal examination; 9 patients with amlodipine-induced gingival overgrowth, 11 patients with inflammatory gingival overgrowth, and 9 healthy individuals as a control group. Clinical periodontal parameters including plaque index (PI), gingival index (GI), and gingival overgrowth index (GOI) were recorded. Blood and gingival crevicular fluid (GCF) samples were obtained. Gingival tissues were taken by appropriate periodontal surgery following initial periodontal therapy. To detect IL-17A on tissue samples, immunohistochemistry (IHC) was performed. Quantitative analysis was done, and the expression level of IL-17A was given as the percent positively stained cells. Enzyme-linked immunosorbent assay (ELISA) kits were used to analyze IL-17A in serum and GCF samples. RESULTS: All recorded clinical parameters were significantly higher in gingival overgrowth groups compared with control. Evaluation of inflammation on tissue sections did not show any significant change within the groups. Immunohistochemistry findings showed that IL-17A expression was increased in amlodipine samples (81.90%) compared with control samples (42.35%) (P < .001). There was an increase in the inflammatory group (66.08%) which is significantly less than the amlodipine group (P < .05). IL-17A levels in serum and GCF samples were not different within the study groups. CONCLUSION: In this study, elevated IL-17A expression regardless of inflammation shows that amlodipine might cause an increase of IL-17A in gingival tissues. This increase might induce fibrotic changes and EMT in gingival overgrowth tissues. The association of IL-17A with fibrosis and EMT in gingival tissues requires further investigation.

Management of Cyclosporine-Influenced Gingival Enlargement With Azithromycin.

INTRODUCTION: Management of drug-influenced gingival enlargement is challenging, and surgery is most often indicated. However, because of a unique mechanism of action, azithromycin helps in the management of gingival enlargement caused by cyclosporine. An incidental observation of the effect of azithromycin in the cyclosporine-influenced gingival enlargement by physicians in 1995 led to series of basic investigations and clinical trials confirming this observation and providing a non-surgical treatment modality. CASE PRESENTATION: In this report, successful management of cyclosporine-influenced gingival enlargement in a 39-year-old renal transplant patient with the use of azithromycin without any surgical intervention is presented. CONCLUSION: Use of azithromycin for managing cyclosporine-influenced gingival enlargement is a useful alternative or adjunct to surgical management. It is hoped that this report will raise further awareness of this non-surgical modality in patients taking cyclosporine.

Amlodipine-induced gingival enlargement: A case report.

Gingival enlargements (GEs) can be caused by local, systemic diseases or drugs. Three molecules can be responsible of GEs: ciclosporin, phenytoin and calcium channel blockers (CCBs). We report the case of a 56-year-old male treated by Amlodipine, a CCB, for hypertension for many years and who recently developed a severe GE affecting both mandibular and maxillary arches inducing dental malposition. The histological examination showed non-specific inflammation with a predominance of lymphocytes. Amlodipine was suspected and suspended in agreement with his physician. One month later, the enlargement significantly reduced but GE was so severe and dental malposition so marked that all the teeth but the canines were extracted. No recurrence was noted one year later. This exceptional case should encourage every practitioner to be vigilant with patient treated with CCBs and their potential side effects and consequences.

Agrandamiento gingival medicamentoso en paciente con trasplante renal tratado con ciclosporina A / Drug-induced gingival enlargement in a kidney transplant patient treated with cyclosporine A

Resumen El agrandamiento gingival medicamentoso se describe como un aumento de volumen anormal, exagerado y deformante de las encías, provocado por la ingesta de algunos medicamentos. Entre los más comunes se encuentran: fármacos anticonvulsivantes, antihipertensivos, particularmente los antagonistas del calcio e inmunosupresores. Se presentó el caso de un paciente del sexo masculino, de 44 años de edad, con antecedentes de hipertensión arterial e insuficiencia renal crónica, durante 10 y tres años respectivamente. Después de 22 meses de haber recibido un trasplante renal y tratamiento con ciclosporina, acude a consulta por aumento del volumen de las encías en ambos maxilares, clínicamente compatible con agrandamiento gingival medicamentoso generalizado y grave.

ABSTRACT Drug-induced gingival enlargement is described as an abnormal, exaggerated, and deforming growth of the gingiva caused by the ingestion of some medications. Anticonvulsants, antihypertensive calcium channel blockers and immunosuppressants are among the most common drugs. We present a 44-year-old male patient with a history of arterial hypertension and chronic renal failure, for 10 and three years, respectively. Twenty-two months after receiving a kidney transplant and treatment with cyclosporine, he visited the clinic due to an increase in the volume of the gums in both jaws, clinically compatible with a generalized and severe gingival enlargement.

Nonsurgical Periodontal Treatment by Erbium:YAG Laser Promotes Regression of Gingival Overgrowth in Patient Taking Cyclosporine A: A Case Report.

Objective and background: To report on a case of cyclosporine A-related gingival overgrowth (GO) treated by conventional scaling and Erbium:YAG laser that unexpectedly showed complete healing with normalization of the gingiva, making unnecessary further surgical treatment for gingival volume reduction. Since Erbium:YAG laser was approved in 1997 by the U.S. Food and Drug Administration for hard and soft tissue treatments in dentistry, several studies have been published to demonstrate its efficacy for bone cutting, plaque and subgingival calculus removal, and antiseptic effects both on soft and hard periodontal tissues. Methods: We report herewith the case of a patient undergoing cyclosporine A therapy, affected by GO who underwent scaling and full mouth disinfection with chlorhexidine 2% rinses, followed by Erbium:YAG laser treatment of gingival pseudopockets, without surgical removal of the overgrown gingiva. Results: Unexpectedly, complete healing of the periodontal tissues was observable after one single laser application and no adjunctive surgical procedure was necessary. Conclusions: Erbium:YAG laser could be considered a really effective option for the nonsurgical treatment of drug-induced GO, avoiding the surgical procedures and also promoting a fast healing and a patient compliance surely higher than conventional techniques.

Agrandamiento gingival medicamentoso en paciente con trasplante renal tratado con ciclosporina A / Drug-induced gingival enlargement in a kidney transplant patient treated with cyclosporine A

El agrandamiento gingival medicamentoso se describe como un aumento de volumen anormal, exagerado y deformante de las encías, provocado por la ingesta de algunos medicamentos. Entre los más comunes se encuentran: fármacos anticonvulsivantes, antihipertensivos, particularmente los antagonistas del calcio e inmunosupresores. Se presentó el caso de un paciente del sexo masculino, de 44 años de edad, con antecedentes de hipertensión arterial e insuficiencia renal crónica, durante 10 y tres años respectivamente. Después de 22 meses de haber recibido un trasplante renal y tratamiento con ciclosporina, acude a consulta por aumento del volumen de las encías en ambos maxilares, clínicamente compatible con agrandamiento gingival medicamentoso generalizado y grave.

Effects of cyclosporin, nifedipine and phenytoin on gingival myofibroblast transdifferentiation in monkeys

Abstract Objective: Myofibroblasts have been associated with the development of several pathologic fibrotic conditions. This longitudinal study aims to assess the proliferative and antiapoptotic effects of cyclosporin, nifedipine and phenytoin on gingival connective tissue cells of nonhuman primate, as well as to analyze a possible role of myofibroblasts in gingival overgrowth. Materials and Methods: Gingival samples from the right superior canine area were obtained from 12 male monkeys ( Sapajus spp ) to comprise the control group. After one week, the animals were randomly assigned to three groups, which received daily oral doses of cyclosporin, nifedipine or phenytoin for 120 days. Gingival samples were collected from the left superior canine area of two animals of each group at 52 and 120 days. Histological sections were stained with hematoxylin and eosin, and immunoreacted against α-SMA, Ki- 67 and bcl-2. Results: α-SMA immunoreaction was negative in the control and experimental groups. Similarly, no difference between groups concerning immunostaining against Ki-67 and bcl-2 was observed in connective tissue cells. Conclusion: Based on this methodology, it may be concluded that gingival overgrowths induced by cyclosporin, nifedipine and phenytoin are not associated with neither myofibroblast transdifferentiation, proliferation nor apoptosis of gingival connective cells in monkeys.

Effects of cyclosporin, nifedipine and phenytoin on gingival myofibroblast transdifferentiation in monkeys.

OBJECTIVE: Myofibroblasts have been associated with the development of several pathologic fibrotic conditions. This longitudinal study aims to assess the proliferative and antiapoptotic effects of cyclosporin, nifedipine and phenytoin on gingival connective tissue cells of nonhuman primate, as well as to analyze a possible role of myofibroblasts in gingival overgrowth. MATERIALS AND METHODS: Gingival samples from the right superior canine area were obtained from 12 male monkeys ( Sapajus spp ) to comprise the control group. After one week, the animals were randomly assigned to three groups, which received daily oral doses of cyclosporin, nifedipine or phenytoin for 120 days. Gingival samples were collected from the left superior canine area of two animals of each group at 52 and 120 days. Histological sections were stained with hematoxylin and eosin, and immunoreacted against α-SMA, Ki- 67 and bcl-2. RESULTS: α-SMA immunoreaction was negative in the control and experimental groups. Similarly, no difference between groups concerning immunostaining against Ki-67 and bcl-2 was observed in connective tissue cells. CONCLUSION: Based on this methodology, it may be concluded that gingival overgrowths induced by cyclosporin, nifedipine and phenytoin are not associated with neither myofibroblast transdifferentiation, proliferation nor apoptosis of gingival connective cells in monkeys.

Reversal of drug-induced gingival overgrowth by UV-mediated apoptosis of gingival fibroblasts - an in vitro study.

Gingival overgrowth (GO) is an undesirable result of certain drugs like Cyclosporine A (CsA). Histopathology of GO shows hyperplasia of gingival epithelium, expansion of connective tissue with increased collagen, or a combination. Factors such as age, gender, oral hygiene, duration, and dosage also influence onset and severity of GO. One of the mechanisms behind uncontrolled cell proliferation in drug-induced GO is inhibition of apoptotic pathways, with a consequent effect on normal cell turnover. Our objective was to determine if UV photo-treatment would activate apoptosis in the gingival fibroblast component. Human gingival fibroblast cells (HGF-1) were exposed to 200ng/ml or 400ng/ml CsA and maintained for 3, 6, and 9 days, followed by UV radiation for 2, 5, or 10min (N=6). Naïve (no CsA or UV), negative (UV, no CsA), and positive controls (CsA, no UV) were designated. Prior to UV treatment, growth media was replaced with 1M PBS to prevent absorption of UV radiation by serum proteins, and cells were incubated in growth media for 24h post-UV before processing for TUNEL assay, cell proliferation assays, or immunofluorescence. Data showed a temporal increase in proliferation of HGF-1 cells under the influence of CsA. The 200ng/ml dose was more effective in causing over-proliferation. UV treatment for 10min resulted in significant reduction in cell numbers, as evidenced by counts and proliferation assays. Our study is a first step to further evaluate UV-mediated apoptosis as a mechanism to control certain forms of GO.

Curcumin inhibits TGF-ß1-induced connective tissue growth factor expression through the interruption of Smad2 signaling in human gingival fibroblasts.

BACKGROUND/PURPOSE: Many fibrotic processes are associated with an increased level of transforming growth factor-ß1 (TGF-ß1). TGF-ß1 can increase synthesis of matrix proteins and enhance secretion of protease inhibitors, resulting in matrix accumulation. Connective tissue growth factor (CTGF) is a downstream profibrotic effector of TGF-ß1 and is associated with the fibrosis in several human organs. Curcumin has been applied to reduce matrix accumulation in fibrotic diseases. This study was aimed to evaluate whether curcumin could suppress TGF-ß1-induced CTGF expression and its related signaling pathway involving in this inhibitory action in primary human gingival fibroblasts. METHODS: The differences in CTGF expression among three types of gingival overgrowth and normal gingival tissues were assessed by immunohistochemistry. Gingival fibroblast viability in cultured media with different concentrations of curcumin was studied by MTT assay. The effect of curcumin on TGF-ß1-induced CTGF expression in primary human gingival fibroblasts was examined by immunoblotting. Moreover, the proteins involved in TGF-ß1 signaling pathways including TGF-ß1 receptors and Smad2 were also analyzed by immunoblotting. RESULTS: CTGF was highly expressed in fibroblasts, epithelial cells and some of endothelial cells, smooth muscle cells, and inflammatory cells in phenytoin-induced gingival overgrowth tissues rather than in those of hereditary and inflammatory gingival overgrowth tissues. Moreover, CTGF expression in the epithelial and connective tissue layers was higher in phenytoin-induced gingival overgrowth tissues than in normal gingival tissues. Curcumin was nontoxic and could reduce TGF-ß1-induced CTGF expression by attenuating the phosphorylation and nuclear translocation of Smad2. CONCLUSION: Curcumin can suppress TGF-ß1-induced CTGF expression through the interruption of Smad2 signaling.

High-power diode laser on management of drug-induced gingival overgrowth: Report of two cases and long-term follow-up.

BACKGROUND: Drug-induced gingival overgrowth (DIGO) is attributed mainly to the prolonged use of calcium channel blocking agents, anticonvulsants, and anti-calcineurin inhibitors . The management of DIGO depends on the severity of the disease and includes surgical intervention and plaque control. Compared to conventional surgical treatment, the recent literature data have shown that gingivectomy using a high-power laser (HPL) is a short and easy procedure, which results in minimal postoperative discomfort and greater patient accep- tance. OBJECTIVE AND METHODS: The purpose of this study was to report two cases of recurrent DIGO treated surgically using HPL (λ 808nm, 1.5W). RESULTS: Minimal bleeding and discomfort were observed during surgery, and patients reported no pain or bleeding after the procedure. After 1 year of follow-up, patients presented a minimal increase of gingival volume, indicating that laser technology can improve the efficiency and prognosis of DIGO. CONCLUSIONS: The HPL was able to preventing hemorrhage and improving the patient's collaboration with the treatment and quality of life.

Lack of pathogenic mutations in SOS1 gene in phenytoin-induced gingival overgrowth patients.

OBJECTIVE: Gingival overgrowth is a side effect associated with some distinct classes of drugs, such as anticonvulsants, immunosuppressants, and calcium channel blockers. One of the main drugs associated with gingival overgrowth is the antiepileptic phenytoin, which affects gingival tissues by altering extracellular matrix metabolism. It has been shown that mutation of human SOS1 gene is responsible for a rare hereditary gingival fibromatosis type 1, a benign gingival overgrowth. The aim of the present study is to evaluate the possible contribution of SOS1 mutation to gingival overgrowth-related phenotype. DESIGN: We selected and screened for mutations a group of 24 epileptic patients who experienced significant gingival overgrowth following phenytoin therapy. Mutation scanning was carried out by denaturing high-performance liquid chromatography analysis of the entire coding region of the SOS1 gene. Novel identified variants were analyzed in-silico by using Alamut Visual mutation interpretation software, and comparison with normal control group was done. RESULTS: Mutation scanning of the entire coding sequence of SOS1 gene identified seven intronic variants and one new exonic substitution (c.138G>A). The seven common intronic variants were not considered to be of pathogenic importance. The exonic substitution c.138G>A was found to be absent in 100 ethnically matched normal control chromosomes, but was not expected to have functional significance based on prediction bioinformatics tools. CONCLUSIONS: This study represents the first mutation analysis of the SOS1 gene in phenytoin-induced gingival overgrowth epileptic patients. Present results suggest that obvious pathogenic mutations in the SOS1 gene do not represent a common mechanism underlying phenytoin-induced gingival overgrowth in epileptic patients; other mechanisms are likely to be involved in the pathogenesis of this drug-induced phenotype.

Phenytoin-induced gingival overgrowth caused by death receptor pathway malfunction.

OBJECTIVE: In this study, we investigated the role of phenytoin (PHT) in death receptor-induced apoptosis of gingival fibroblasts to clarify the mechanism of PHT-induced gingival overgrowth. METHODS: Human gingival fibroblasts were cultured to semiconfluence and treated with PHT (0.025, 0.1, 0.25, and 1.0 µM) for 48 h, and then, the apoptotic cell numbers were relatively determined by absorptiometry. After 24 h of 0.25 µM PHT treatment, caspase activity was measured by absorptiometry, apoptotic and cell cycle phase distribution was analyzed by flow cytometry, expression levels of apoptotic genes were quantified by real-time qPCR, and expression of apoptotic proteins was detected by Western blot analysis. After 48 h of 0.25 µM PHT treatment, appearance of apoptotic cells was detected by TUNEL assay. RESULTS: PHT treatment decreased the proportion of apoptotic cells in gingival fibroblasts compared to a serum-free control culture in response to the protein changes as follows: PHT upregulated c-FLIP and, in turn, downregulated FADD, caspase-8, and caspase-3; PHT upregulated c-IAP2 and downregulated TRAF2; PHT downregulated caspase-9 and caspase-3 via decreased RIPK1 activity and increased Bcl-2 activity. CONCLUSION: PHT-induced gingival overgrowth may result from the above-mentioned mechanisms involving apoptosis inhibition in gingival fibroblasts.