Effect of phenytoin medication on the metabolism of epidermal growth factor receptor in cultured gingival fibroblasts

Role of Epithelial Mesenchymal Transition in Phenytoin Influenced Gingival Overgrowth in Children and Young Adults. A Preliminary Clinical and Immunohistochemical Study

Objectives: To prove the role of epithelial mesenchymal transition (EMT) in the pathogenesis of phenytoin influenced gingival overgrowth (PIGO) in children and young adults. Study design: Thirty male individuals who are to start with oral phenytoin therapy were recruited for the study. All the 30 individuals underwent full mouth scaling and root planning and were then followed up for a period of one year at intervals of 3 months each. Based on the clinical gingival status they were divided into group1 (responders) individuals who showed gingival overgrowth (GO) and group 2 (non responders) individuals who do not show any GO. Gingival tissue samples were obtained from both the groups at the end of 1 year and subjected to immuno histochemical analysis for E-cadherin expression and histo-pathological for alteration in the basement membrane and confirmation of the fibrosis. Results: Decrease in expression of E cadherin, loss of basement membrane integrity and fibrosis were noted on responder group when compared to non responder group at p<0.001. Fibrosis was seen in the epithelial connective tissue junction. Conclusion: Decrease in cell adhesion, degradation of basement membrane and presence of fibrosis could suggest the role of EMT in the pathogenesis of PIGO.

Phenytoin-induced gingival overgrowth

Gingival overgrowth is a common adverse effect of therapy with Phenytoin, having important medical and cosmetic implications. Poor periodontal hygiene is an important risk factor for severity of Phenytoin-induced gingival overgrowth (PIGO), which is a time-dependent process. There is complex interplay of altered fibroblast biology, connective tissue turnover, inflammatory processes, and growth factors on a background of genetic susceptibility to produce increase in various components of interstitial matrix in PIGO tissue. Treatment options have included change of PHT to another anti-seizure drug, measures to improve periodontal hygiene and gingivectomy. There is conclusive evidence that folic acid supplementation significantly decreases the incidence of PIGO.

Down-regulation of epidermal growth factor receptor-dependent signaling by Porphyromonas gingivalis lipopolysaccharide in life-expanded human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Human gingival fibroblasts exhibit proliferative responses following epidermal growth factor exposure, which are thought to enhance periodontal regeneration in the absence of bacterial products such as lipopolysacharide. However, lipopolysaccharide challenge activates human gingival fibroblasts to release several inflammatory mediators that contribute to the immune response associated with periodontitis and attenuate wound repair. We tested the hypothesis that Porphyromonas gingivalis lipopolysaccharide-activated signaling pathways down-regulate epidermal growth factor receptor-dependent events.

MATERIAL AND METHODS

To study lipopolysaccharide/epidermal growth factor interactions in human gingival fibroblasts, we introduced the catalytic subunit of human telomerase into human gingival fibroblasts, thereby generating a more long-lived cellular model. These cells were characterized and evaluated for lipopolysaccharide/epidermal growth factor responsiveness and regulation of epidermal growth factor-dependent pathways.

RESULTS

Comparison of human telomerase-transduced gingival fibroblasts with human gingival fibroblasts revealed that both cell lines exhibit a spindle-like morphology and express similar levels of epidermal growth factor receptor, CD14 and Toll-like receptors 2 and 4. Importantly, human telomerase-transduced gingival fibroblasts proliferation rates are increased 5-9 fold over human gingival fibroblasts and exhibit a longer life span in culture. In addition, human telomerase-transduced gingival fibroblasts and human gingival fibroblasts exhibit comparable profiles of mitogen-activated protein kinase kinase (extracellular signal-regulated kinase 1/2) activation upon epidermal growth factor or P. gingivalis lipopolysaccharide administration. Interestingly, treatment with P. gingivalis lipopolysaccharide leads to a down-regulation of epidermal growth factor-dependent extracellular signal-regulated kinase 1/2, p38 and cyclic-AMP response element binding protein phosphorylation in both cell types.

CONCLUSION

These studies demonstrate that human telomerase-transduced gingival fibroblasts exhibit an extended life span and recapitulate human gingival fibroblasts biology. Moreover, this system has allowed for the first demonstration of lipopolysaccharide down-regulation of epidermal growth factor activated pathways in human gingival fibroblasts and should facilitate the analysis of signaling events relevant to the pathogenesis and treatment of periodontitis.

Impaired degradation of matrix collagen in human gingival fibroblasts by the antiepileptic drug phenytoin

BACKGROUND

Gingival overgrowth (GO) is a serious adverse effect associated with the administration of phenytoin (PHT), with PHT-induced GO characterized by a massive accumulation of extracellular matrix components, especially collagen, in gingival connective tissues. However, the etiology of such collagen accumulation is still largely unknown. We examined the effects of PHT on the collagen degradation process leading to collagen accumulation in human gingival fibroblasts (HGF).

METHODS

HGFs were cultured with various concentrations of PHT and viable cell numbers and collagen amounts were determined. Gene and protein expressions of matrix metalloproteinases (MMP) and tissue inhibitors of MMPs (TIMP) were quantified with reverse transcription-polymerase chain reaction (RT-PCR) analyses and Western blotting, respectively. Cellular endocytosis of collagen was assayed using flow-cytometric analysis. The effects of PHT on extracellular signal-regulated kinase 1/2 (ERK1/2) and inhibitor kappaB-alpha (IkappaB-alpha) were assayed.

RESULTS

The proliferation of HGFs was not affected by PHT, whereas it significantly increased collagen accumulation. Further, the expressions of MMP-1, -2, and -3 were markedly suppressed by PHT, whereas that of TIMP-1 was induced in a dose- and time-dependent manner. PHT also markedly prevented collagen endocytosis by HGFs, which was associated with the suppression of alpha2beta1-integrin expression. In addition, the phosphorylation of ERK1/2 and IkappaB-alpha degradation were suppressed by PHT.

CONCLUSIONS

These results suggest that PHT causes an impaired degradation of collagen by suppression of enzymatic degradation with MMPs/TIMP-1 and alpha2beta1-integrin-mediated endocytosis. Those alterations are likely mediated through the cellular signaling pathways of ERK1/2 and nuclear factor kappaB. These synergistic effects may cause collagen accumulation, leading to GO.

The subgingival microflora in phenytoin-induced gingival hyperplasia

OBJECTIVES

Microbial flora and gingival conditions were compared between a group of patients with phenytoin-induced gingival hyperplasia as a test group, a control group of patients who were administered phenytoin without gingival hyperplasia and a blank group who took no phenytoin and no gingival hyperplasia in mentally retarded patients.

MATERIALS AND METHODS

Subgingival plaque samples were collected from a PHT-induced overgrown gingival pocket and microbiological experiments were performed by culture and PCR methods.

RESULTS

The predominant genera in total cultivable bacteria from subgingival plaque samples were streptococcus and actinomyces with recovery ranges of 37.6-42.1% and 23.4-25.5% of total bacteria, respectively, in all groups. The test group showed a significantly higher level of obligate Gram-negative rods than the control and blank groups. Black-pigmented obligate anaerobic Gram-negative rods were detected in 10.3% of total cultivable bacteria in the test group. The black-pigmented rods were predominantly Prevotella intermedia in the test group and Prevotella nigrescens in the control and blank groups. Porphyromonas gingivalis and Porphyromonas endodontalis were also detected in the test group with small values.

CONCLUSIONS

These results suggested that black-pigmented rods, particularly P. intermedia, could be habitable in the environment of gingival hyperplasia.

Phenytoin-mediated androgen metabolism in gingival fibroblasts. Effects of the antiandrogen finasteride and the alkaline phosphatase inhibitor levamisole

OBJECTIVES

This investigation attempts to identify the role of the alkaline phosphatase inhibitor levamisole (L) and the antiandrogen finasteride (F) on 5alpha-reductase activity in gingival fibroblasts, to elucidate mechanisms for phenytoin-induced gingival overgrowth.

MATERIAL AND METHODS

Human gingival fibroblasts were incubated with Eagle's MEM and 14C-testosterone/14C-4-androstenedione as substrates; effective concentrations of phenytoin (Ph), levamisole (L) and finasteride (F), alone and in combinations of (Ph + F) (Ph + L) were added to the incubate. After 24 h, the medium was analysed for steroid metabolites and quantified using a radioisotope scanner.

RESULTS

The metabolites isolated were 5alpha-dihydrotestosterone (DHT), 4-androstenedione (4-A) or testosterone (T) from each substrate. With 14C-T as substrate, Ph stimulated DHT synthesis by 1.7-fold, while F and L inhibited this activity by 1.8-fold and 34%, respectively (n = 6; P < 0.001). The combination of Ph + F reduced yields by 2.7-fold compared with Ph alone and Ph + L reduced DHT synthesis by 2.4-fold compared with Ph alone (n = 6; P < 0.001). When 14C-4-androstenedione was used as substrate, similar trends were identified.

CONCLUSION

These results suggest that the alkaline phosphatase inhibitor levamisole and the 5alpha-reductase inhibitor finasteride can substantially decrease the yields of DHT in fibroblasts, stimulated by phenytoin. This could be a potential target for reducing the gingival overgrowth caused by phenytoin.

Heparan sulfate interacting protein (HIP/L29) negatively regulates growth responses to basic fibroblast growth factor in gingival fibroblasts

Basic fibroblast growth factor (bFGF) modulates gingival growth, and its release from heparan sulfate (HS) in the extracellular matrix (ECM) governs local tissue bioavailability. We identified a heparin/HS interacting protein (HIP/L29) that recognizes specific HS sequences. We hypothesize that HIP/L29, by modulating the interactions of bFGF with HS chains on proteoglycans, could regulate bFGF bioavailability. To investigate interactions between bFGF and HIP/L29, we isolated and cultured fibroblasts from normal gingiva and overgrown gingiva from patients on cyclosporine (CSA). bFGF significantly stimulated gingival fibroblast proliferation with or without heparin. Recombinant human HIP/L29 dramatically decreased bFGF-induced proliferation, but did not alter responses to insulin-like growth factor-1 (IGF-1). Analysis of mitogen-activated protein kinase (MAPK) phosphorylation patterns showed that bFGF stimulation of p44 (Erk-1), but not p42 (Erk-2), also was inhibited by HIP/L29 in a dose-dependent manner. Together, these results support our hypothesis that HIP/L29 modulates the bioavailability and action of bFGF.

Immunohistochemical analysis of epidermal growth factor receptor in cyclosporin A-induced gingival overgrowth

Cyclosporin A (CsA)induced gingival overgrowth represents a tissue of fibrosis and epidermal growth factor (EGF) has been shown to induce extracellular matrix synthesis by fibroblasts. The purpose of this study was to evaluate the expression of EGF-receptor (EGF-r) in frozen sections of CsA-induced overgrown gingival tissue using immunohistochemical and semiquantitative techniques. Gingival biopsies were obtained from 12 renal transplant patients receiving CsA as well as 9 systemically and periodontally healthy individuals. Immunohistochemical staining procedures were carried out in frozen sections of gingival tissue and the expression of EGF-r was compared between the two study groups. The expression of EGF-r was more pronounced in the oral gingival epithelium of CsA-induced overgrown gingiva as compared to those of the clinically healthy gingival specimens. The reactivity in the inflammatory infiltrate and connective tissue cells of both of the study groups was similar. In conclusion, the results of the present study may suggest that CsA affects EGF-r metabolism in gingival keratinocytes resulting in an increased number of cell surface receptors, which may eventually play a role in the pathogenesis of gingival tissue alterations.

The effects of human mast-cell products and of phenytoin on androgen 5alpha-reductase expression in human gingival fibroblasts

The aim was to elucidate mechanisms for phenytoin-induced gingival overgrowth, using effects of type 1 human mast cell (HMC-1) supernatant and histamine on the expression of 5alpha-reductase in human gingival fibroblasts (HGF), and the effects of phenytoin on this activity. Duplicate incubations of HGF in Eagle's minimum essential medium (MEM) were performed with [14C] testosterone and serial concentrations of mast-cell histamine (1-100 microgram/ml)/HMC-1 culture supernatant at serial dilutions of 1-100 microl/ml for 24 h. Other experiments employed optimal concentrations of HMC-1 supernatant (10 microl/ml) or histamine (8 microgram/ml) and phenytoin (1 and 5 microgram/ml), alone and in combination, using two androgen substrates, [14C] testosterone and [14C] 4-androstenedione. At the end of a 24-h incubation the medium was solvent-extracted for steroid metabolites, analysed and quantified in a radioisotope scanner. HMC-1, histamine (n=3) and phenytoin (n=6) significantly increased the synthesis of dihydrotestosterone and 4-androstenedione by up to 80% (P<0.01); the combination of HMC-1 and phenytoin caused two-fold increases (n=6; P<0.01). The incubations with histamine alone and in combination with phenytoin showed significant stimulation of dihydroxytestosterone and the diols alone and in combination, which was less pronounced in combination. This investigation demonstrates significant stimulation of 5alpha-reductase activity in human gingival fibroblasts by mast-cell supernatant and a specific product histamine, alone and in combination with phenytoin. Androgen 5alpha-reductase-mediated anabolic actions in connective tissue are well documented. The findings suggest a novel hypothesis that mast-cell mediated androgen action in the gingiva in response to phenytoin could contribute to gingival overgrowth.

Connective tissue growth factor in drug-induced gingival overgrowth

BACKGROUND

Drug-induced gingival overgrowth is a known side effect of certain chemotherapeutic agents used for the treatment of systemic disorders. The pathogenesis and mechanisms responsible for this condition are not fully understood. This study assesses for the presence and localization of connective tissue growth factor (CTGF) in drug-induced gingival overgrowth tissues. CTGF immunostaining was compared with sections stained with transforming growth factor (TGF)-beta1 and CD31 antibodies in order to investigate possible pathogenic mechanisms.

METHODS

Gingival overgrowth samples were obtained from patients undergoing therapy with phenytoin (n = 9), nifedipine (n = 4), cyclosporin A (n = 5), and control tissues from systemically healthy donors (n = 9). Tissue sections were subjected to peroxidase immunohistochemistry and were stained with CTGF and TGF-beta1 polyclonal primary antibodies. Possible relationships between CTGF staining and angiogenesis were also studied using an anti-CD31 antibody as a marker for endothelial cells. Staining was analyzed by computer-assisted quantitative and semiquantitative methodology at 5 defined sites in all samples based on the location of specific landmarks including epithelium and underlying connective tissues.

RESULTS

Cellular and extracellular CTGF content in phenytoin gingival overgrowth tissues was significantly (P<0.05) higher compared to the other gingival overgrowth tissues and the controls. Higher CTGF staining in phenytoin gingival overgrowth tissues was accompanied by an increased abundance of fibroblasts and connective tissue fibers. No strong association of CTGF staining with TGF-beta1 or CD31 staining was found.

CONCLUSIONS

The data from the present study show significantly higher CTGF staining in phenytoin-induced gingival overgrowth tissues compared to controls, cyclosporin A-, or nifedipine-induced gingival overgrowth. Moreover, semiquantitative analyses of histologic samples support the concept that the phenytoin overgrowth tissues are fibrotic. These associations suggest a possible role for CTGF in promoting development of fibrotic lesions in phenytoin-induced gingival overgrowth.

Expression of growth-factor receptors in normal and regenerating human periodontal cells

Growth factors are biologically active mediators that bind to specific receptors on target cells and regulate genes involved in cell growth, wound healing and regeneration. The expression of these receptors is thus of fundamental importance for the response of the cells to the factors. The aim here was to examine, using immunohistochemistry and flow cytometry, the expression of growth factor receptors in normal gingiva, periodontal ligament and in cells derived from these tissues, and also in regenerated tissues following guided tissue regeneration (GTR). By immunocytochemistry platelet-derived growth factor receptor-alpha (PDGF-Ralpha) was not detected in any of the tissues, whereas the PDGF-Rbeta and transforming growth factor-beta receptor types I and II (TGF-beta RI, RII) appeared to be upregulated in regenerated tissues compared with gingival and periodontal ligament tissues. Epidermal growth factor receptor (EGF-R) was also notably elevated in the regenerated tissue and was strongly expressed in the gingival epithelium but not in the periodontal ligament. Neither were fibroblast growth factor receptor-I (FGF-RI) or insulin-like growth factor receptor (IGF-R) detected in the periodontal ligament, nor in the gingiva, but they sometimes stained weakly in the regenerated tissues. Flow cytometry (FCM) showed that all the cells derived from the normal gingiva and the periodontal ligament expressed the PDGF-Rbeta, whereas the TGF-beta RI and RII, FGF-RI and IGF-R were detected in only a proportion of the total cells. In contrast, none of the cells expressed the PDGF-Ralpha or the EGF-R. These observations show that the growth factor receptors are differentially expressed by the periodontal tissues and cells and suggest that the corresponding factors may also be differentially involved in periodontal wound healing and regeneration.

Medication induced gingival overgrowth

A number of idiopathic, pathological and pharmacological reactions may result in an overgrowth of the gingiva. This review concentrates on those overgrowths associated with various pharmacological agents. The pharmaco-kinetics and side effects of each drug associated with gingival overgrowth are discussed along with the clinical and histological features and treatment. By examining the possible pathogeneses for these overgrowths we propose a unifying hypothesis for the causation based around inhibition of apoptosis and decreased collagenase activity modulated by cytoplasmic calcium.

The effects of epidermal growth factor, interleukin-1, and phenytoin, alone and in combination, on C19 steroid conversions in fibroblasts

The formation of the biologically active metabolite 5 alpha-dihydrotestosterone (DHT) from testosterone in response to phenytoin (Ph), interleukin-1 (IL-1), and epidermal growth factor (EGF) was investigated. The androgen DHT stimulates matrix synthesis in connective tissue and bone. Duplicate incubations were performed with confluent human gingival fibroblasts, 14C-testosterone, and optimal stimulatory concentrations of IL-1 (5 IU/ml), EGF (10 ng/ml), Ph (5 micrograms/ml), Ph + EGF, and Ph + IL-1 respectively for 24 hours in Eagle's MEM at 37 degrees C. The medium was then analyzed for radioactive metabolites. Similar incubations were performed with human gingival tissue using 14C-4-androstenedione as substrate in the presence or absence of EGF, Ph, and EGF + Ph. In the cell lines studied, EGF stimulated DHT and 4-androstenedione synthesis by 20% (n = 5; P < 0.01; Wilcoxon signed rank statistic for paired observations). IL-1 stimulated DHT and 4-androstenedione synthesis by 2-fold (n = 6; P < 0.01). Ph stimulated DHT and 4-androstenedione synthesis by 2-fold increases (n = 3; P < 0.01). Combinations of phenytoin and EGF stimulated DHT and 4-androstenedione synthesis by 33% and 37% greater than the effect of phenytoin alone (n = 3; P < 0.01). Combinations of Ph and IL-1 caused a 45% increase in the amount of DHT formed and a 66% increase in 4-androstenedione when compared to the effect of phenytoin alone (n = 3; P < 0.01). 14C-4-androstenedione was converted to DHT and testosterone by human gingival tissue. There were 2-fold, 4-fold, and 2.5-fold increases in DHT synthesis and 5-fold, 2-fold, and 6-fold increases in the formation of testosterone in response to EGF, Ph, and EGF + Ph respectively (n = 3; P < 0.01). EGF and IL-1 present in inflammatory exudate may have implications on phenytoin-induced overgrowth via the steroid metabolic pathway.

The pathogenesis of drug-induced gingival overgrowth

Gingival overgrowth is a well-documented unwanted effect, associated with phenytoin, cyclosporin, and the calcium channel blockers. The pathogenesis of drug-induced gingival overgrowth is uncertain, and there appears to be no unifying hypothesis that links together the 3 commonly implicated drugs. In this review, we consider a multifactorial model which expands on the interaction between drug and/or metabolite, with the gingival fibroblasts. Factors which impact upon this model include age, genetic predisposition, pharmacokinetic variables, plaque-induced inflammatory and immunological changes and activation of growth factors. Of these, genetic factors which give rise to fibroblast heterogeneity, gingival inflammation, and pharmacokinetic variables appear to be significant in the expression of gingival overgrowth. A more thorough understanding of the pathogenesis of this unwanted effect will hopefully elucidate appropriate mechanisms for its control.

Effect of 5-(p-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) enantiomers, major metabolites of phenytoin, on the occurrence of chronic-gingival hyperplasia: in vivo and in vitro study

The purpose of this study was to assess the possible role of the (R)- and (S)- enantiomers of the phenytoin metabolite p-HPPH in the pathogenesis of gingival hyperplasia (GH). About 98% of circulating p-HPPH is in the (S)-form. There were significant differences between patients with and without GH in (R)-p-HPPH level (0.055 vs 0.042 microgram.ml-1), both enantiomer/racemate level ratios, and R/S enantiomeric ratio (0.0313 vs 0.0232); an increase in serum (R)-p-HPPH level was observed in patients with GH. In separate experiments, the effect of p-HPPH enantiomers on the proliferation of the normal human dermal fibroblast was studied. The in vitro study showed that (R)-p-HPPH selectively stimulated fibroblast growth. The results suggest that the least abundant metabolite, (R)-p-HPPH, is the most toxic with respect to gingival hyperplasia.

A 15-year follow-up of phenytoin-induced unilateral gingival hyperplasia: a case report

INTRODUCTION-The aim of this case report is to present a 15-year follow-up of a patient with phenytoin (PHT) intoxication with unilateral gingival hyperplasia (GH). MATERIAL AND METHODS-A 50-year-old woman was followed-up for 15 years clinically and paraclinically after a heavy PHT intoxication. Her immunoglobulins in serum were checked on PHT and after 15 years treatment with carbamazepine. RESULTS-A gross mass of hyperplasia tissue found primarily in the left side of her mouth had disappeared and serum IgA which was subnormal at the first visit had normalized. CONCLUSION-It is possible to prevent GH from PHT treatment by intensive dental care, correct mouth hygiene and by change of treatment of carbamazepine.

Signal transduction mechanisms in mesenchymal cells

Mesenchymal cells are continually stimulated by a wide spectrum of biological mediators. These mediators bind to receptors on the cell surface and initiate a cascade of signaling events. The initial signal transduction pathways known to be stimulated in mesenchymal cells included phospholipase C, phospholipase D, phospholipase A2, adenylate cyclase, receptor tyrosine kinases, and receptor serine/threonine kinases. These pathways are reviewed and specific applications for therapeutic intervention in wound healing and regenerative therapy in the periodontium are discussed.

On the mechanism of drug-induced gingival hyperplasia

Proposed mechanisms of the side effect of drug-induced gingival hyperplasia are reviewed. Hypotheses with regard to inflammation from bacterial plaque, increased sulfated glycosaminoglycans, immunoglobulins, gingival fibroblast phenotype population differences, epithelial growth factor, pharmacokinetics and tissuebinding, collagenase activation, disruption of fibroblast cellular sodium/calcium flux, folic acid and a combination hypothesis are evaluated.