Expression of fibronectin-binding integrins in gingival epithelium in drug-induced gingival overgrowth

Drug-Induced Gingival Overgrowth—Molecular Aspects of Drug Actions

Drug-induced gingival overgrowth (DIGO) is one of the side effects produced by therapeutic agents, most commonly phenytoin, nifedipine and cyclosporin A. However, the precise mechanism of DIGO is not entirely understood. A literature search of the MEDLINE/PubMed databases was conducted to identify the mechanisms involved in DIGO. The available information suggests that the pathogenesis of DIGO is multifactorial, but common pathogenic sequelae of events emerge, i.e., sodium and calcium channel antagonism or disturbed intracellular handling of calcium, which finally lead to reductions in intracellular folic acid levels. Disturbed cellular functions, mainly in keratinocytes and fibroblasts, result in increased collagen and glycosaminoglycans accumulation in the extracellular matrix. Dysregulation of collagenase activity, as well as integrins and membrane receptors, are key mechanisms of reduced degradation or excessive synthesis of connective tissue components. This manuscript describes the cellular and molecular factors involved in the epithelial–mesenchymal transition and extracellular matrix remodeling triggered by agents producing DIGO.

Gingival Enlargement Caused by Calcium Channel Blockers

Calcium channel blockers, a group of drugs widely used in the treatment of cardiovascular patients, although effective, often cause gingival enlargement, a side effect that is rarely recognized in clinical practice and is not given sufficient importance. Gingival enlargement caused by calcium channel blockers can be localized or generalized, mild or severe. It can negatively affect patients’ appearance, mastication, and speech, thus considerably reducing the quality of life of patients. Risk factors and pathogenesis of this side effect have been the subject of many studies but are still unknown, making this condition a major therapeutic challenge, especially if the cessation of the offending drug is not possible. This study aimed to review the etiology, potential risk factors, pathogenesis, clinical features, and therapy possibilities for gingival enlargement caused by calcium channel blockers.

Gingival overgrowth induced by anticonvulsant drugs: A cross-sectional study on epileptic patients

OBJECTIVE

Our aim was to estimate the prevalence of gingival overgrowth (hyperplasia) and to determine whether active molecules affect the severity of overgrowth in a group of epileptic patients.

BACKGROUND

The effects of phenytoin on oral health have been explored in different studies, yet little information is available on other antiepileptic drugs.

METHODS

Data were collected from 213 subjects of both sexes, from 5 to 80 years. Patients taking the same antiepileptic therapy for at least 1 year and meeting the inclusion criteria of the study (n = 162) were subjected to measurement of gingival overgrowth according to the modified Harris and Ewalt classification and O'Leary's plaque control record (OLR). Descriptive statistics were calculated. Data were analyzed using Pearson's r correlation coefficient and chi-square test. Significance level was set at 5%.

RESULTS

The active drugs lamotrigine, oxcarbazepine, and phenobarbital were significantly associated with gingival overgrowth in 61%, 71%, and 53% of cases, respectively, and phenytoin, valproic acid, and carbamazepine in 50%, 44%, and 32% of cases, respectively.

CONCLUSION

Different antiepileptic molecules may be related to gingival overgrowth. In addition to phenytoin, also lamotrigine, oxcarbazepine, and phenobarbital were associated with increased prevalence of gingival overgrowth. In the management of epileptic patients, dentists should take into account different drugs as possible causes for gingival overgrowth and warn for possible alternatives.

On the Cellular and Molecular Mechanisms of Drug-Induced Gingival Overgrowth

Introduction:

Gingival overgrowth has been linked to multiple factors such as adverse drug effects, inflammation, neoplastic processes, and hereditary gingival fibromatosis. Drug-induced gingival overgrowth is a well-established adverse event. In early stages, this gingival enlargement is usually located in the area of the interdental papilla. Histologically, there is an increase in the different components of the extracellular matrix.

Objective:

The aim of this manuscript is to describe and analyze the different cellular and molecular agents involved in the pathogenesis of Drug-induced gingival overgrowth.

Method:

A literature search of the MEDLINE/PubMed database was conducted to identify the mechanisms involved in the process of drug-induced gingival overgrowth, with the assistance of a research librarian. We present several causal hypotheses and discuss the advances in the understanding of the mechanisms that trigger this gingival alteration.

Results:

In vitro studies have revealed phenotypic cellular changes in keratinocytes and fibroblasts and an increase of the extracellular matrix with collagen and glycosaminoglycans. Drug-induced gingival overgrowth confirms the key role of collagenase and integrins, membrane receptors present in the fibroblasts, due to their involvement in the catabolism of collagen. The three drug categories implicated: calcineuron inhibitors (immunosuppressant drugs), calcium channel blocking agents and anticonvulsant drugs appear to present a multifactorial pathogenesis with a common molecular action: the blockage of the cell membrane in the Ca2+/Na+ ion flow. The alteration of the uptake of cellular folic acid, which depends on the regulated channels of active cationic transport and on passive diffusion, results in a dysfunctional degradation of the connective tissue. Certain intermediate molecules such as cytokines and prostaglandins play a role in this pathological mechanism. The concomitant inflammatory factor encourages the appearance of fibroblasts, which leads to gingival fibrosis. Susceptibility to gingival overgrowth in some fibroblast subpopulations is due to phenotypic variability and genetic polymorphism, as shown by the increase in the synthesis of molecules related to the response of the gingival tissue to inducing drugs. The authors present a diagram depicting various mechanisms involved in the pathogenesis of drug-induced gingival overgrowth.

Conclusion:

Individual predisposition, tissue inflammation, and molecular changes in response to the inducing drug favor the clinical manifestation of gingival overgrowth.

Role of transforming growth factor-beta1 in cyclosporine-induced epithelial-to-mesenchymal transition in gingival epithelium

BACKGROUND

It has been proposed that cyclosporin A (CsA) may induce epithelial-to-mesenchymal transition (EMT) in gingiva. The aims of the present study are to confirm the notion that EMT occurs in human gingival epithelial (hGE) cells after CsA treatment and to investigate the role of transforming growth factor beta1 (TGF-β1) on this CsA-induced EMT.

METHODS

The effects of CsA, with and without TGF-β1 inhibitor, on the morphologic changes of primary culture of hGE cells were examined in vitro. The changes of protein and messenger RNA (mRNA) expressions of two EMT markers (E-cadherin and alpha-smooth muscle actin) in the hGE cells after CsA treatment with and without TGF-β1 inhibitor were evaluated with immunocytochemistry and real-time polymerase chain reaction.

RESULTS

The epithelial cells became spindle-like, elongated, and disassociated from neighboring cells and lost their original cobblestone monolayer pattern when CsA was added. However, the epithelial cells stayed in their original cobblestone morphology with treatment of TGF-β1 inhibitor on top of the CsA treatment. When CsA was given, the protein and mRNA expressions of E-cadherin and α-SMA were significantly altered, and these alterations were significantly reversed with pretreatment of TGF-β1 inhibitor.

CONCLUSIONS

CsA could induce Type 2 EMT in gingiva by changing the morphology of epithelial cells and altering the EMT markers/effectors. The CsA-induced gingival EMT is dependent or at least partially dependent on TGF-β1.

Potential mechanism for osseointegration of dental implants in Zucker diabetic fatty rats

Our aim was to investigate the impact of diabetes mellitus and different durations of glycaemic control on early osseointegration of dental implants, and to explore possible mechanisms by measuring the expression of integrin α5β1 and fibronectin in bone around the implant. We divided 33 male Zucker diabetic fatty (ZDF) rats aged 3 months into 3 groups. The first group comprised diabetic rats with dental implants (controls); the second group was treated with insulin and implants were placed simultaneously (exenatide alone group); and the third group was treated with insulin until the serum glucose was at a constant concentration (< 16 mmol/L), and implants were then inserted (exenatide+normal glucose group). Rats were killed 7, 14, 30, and 60 days after implants had been inserted. The expression of integrin α5β1 and fibronectin in bone around the implants was detected by immunohistochemical analysis in each group. The expression in the exenatide+normal glucose group was stronger than in the other 2 groups. Fourteen days after implantation, expression of integrin α5β1 in the exenatide alone group was significantly stronger than that in the control group (p=0.027), and 60 days after implantation the expression of fibronectin in the exenatide alone group was also significantly stronger than that among the controls (p=0.001). Both fibronectin and integrin α5β1 participate in the adhesion of osteoblasts and act as signals at the bone/implant interface. Diabetes interferes with the osseointegration of implants by deferring expression of fibronectin and integrin α5β1.

Recurrent gingival fibrous lesions: comparison of 2 cases and potential need for additional classification

Historically, the classification of localized gingival fibrous lesions has been inconsistent, leading to multiple naming schemes and confusion among pathologists. Currently, lesions are broadly grouped into localized hyperplastic lesions and true neoplasms. Although some cases are clearly defined histologically (i.e., peripheral ossifying fibroma, peripheral odontogenic fibroma), another set of "reactive" fibrous lesions exhibit overlapping histologic features including nondistinctive fibrosis and inflammation. This group can exhibit recurrence, classically related to a local stimulus. However, when local factors are absent, recurrence suggests inherent neoplastic potential. Herein, we describe 2 recurrent fibrous gingival masses, one of which reportedly recurred 3 times with no obvious inciting agent. The histologic appearance of both lesions was similarly distinctive but not well classifiable, while the immunohistochemical profile indicated divergent lesions. This highlights the need for further study of recurrent gingival fibrous lesions to better predict independent growth potential.

Effect of nifedipine on the expression of keratinocyte growth factor and its receptor in cocultured/monocultured fibroblasts and keratinocytes

BACKGROUND AND OBJECTIVE

Keratinocyte growth factor (KGF) and its receptor (KGFR) are involved in hyperplastic diseases. This study explored the effect of intercellular communication on KGF and KGFR in cocultured/monocultured gingival fibroblasts and keratinocytes following treatment with nifedipine.

MATERIAL AND METHODS

Human gingival fibroblasts and keratinocytes were monocultured and cocultured, respectively. MTT was used to investigate the effects of nifedipine on the proliferation of gingival fibroblasts and keratinocytes. Monoculture and coculture systems were treated with different concentrations (0, 0.2 or 20 μg/mL) of nifedipine, and the expression of KGF and KGFR mRNAs was examined by RT-PCR, whilst the secretion of KGF and the expression of KGFR on the membrane were analyzed using ELISA and flow cytometry, respectively.

RESULTS

Nifedipine (0, 0.2 and 20 μg/mL) had no influence on cell proliferation within 3 d. KGF and KGFR mRNAs were up-regulated, but only in the cocultures. In coculture, the secretion of KGF was significantly increased by nifedipine, while it was only significantly up-regulated by 20 μg/mL of nifedipine in monoculture. Moreover, the level of KGFR protein in the membrane was significantly increased by 20 μg/mL of nifedipine in monocultures, while it was significantly down-regulated by 20 μg/mL of nifedipine in cocultures.

CONCLUSION

The expression of KGF and KGFR are influenced by the interplay of gingival keratinocytes and fibroblasts. Epithelial keratinocytes and mesenchymal fibroblasts may interplay to dynamically regulate gene expression, which may have an effect on the gingival condition following treatment with nifedipine.

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.

Increased expression of integrin alpha2 and abnormal response to TGF-beta1 in hereditary gingival fibromatosis

OBJECTIVE

To investigate the possible correlation between integrin alpha1, alpha2, and beta1 expression and excessive collagen synthesis in fibroblasts from 3 unrelated Chinese families with hereditary gingival fibromatosis (HGF).

DESIGN

Gingival fibroblasts from three Chinese HGF patients and three healthy subjects were included. The expression of alpha1, alpha2, and beta1 integrin subunits was examined by immunohistochemistry, quantitative PCR, and flow cytometry. We also investigated the effects of transforming growth factor-beta1 (TGF-beta1) on the expression of these integrin subunits.

RESULTS

Our results demonstrate that the expression of alpha2 was significantly higher in HGF fibroblasts compared with control fibroblasts (P < 0.01). No significant differences in the expression of alpha1 and beta1 were detected. Furthermore, TGF-beta1 promoted the expression of alpha1 and alpha2 in fibroblasts from both HGF patients and controls. However, it had a larger effect on the expression of alpha2 in HGF fibroblasts than in control cells. In contrast, alpha1 expression was stimulated more in control fibroblasts.

CONCLUSION

The increased expression of integrin alpha2 and the increased response to TGF-beta1 of HGF fibroblasts may be related to the excessive collagen deposition in HGF patients.