Apoptosis in gingival overgrowth tissues

18‑α‑glycyrrhetinic acid induces apoptosis in gingival fibroblasts exposed to phenytoin

Phenytoin (PHT)-induced gingival overgrowth is caused by the increased proliferation and reduced apoptosis of gingival fibroblasts in inflammatory gingiva. Licorice has long been used as a component of therapeutic preparations. It inhibits cell proliferation, induces cell apoptosis and has anti-inflammatory effects. 18-α-glycyrrhetinic acid (18α-GA), the active compound in licorice, promotes apoptosis in various types of cells. The present study determined whether 18α-GA affects apoptosis in gingival fibroblasts exposed to PHT. The present study aimed to establish a basis for the therapeutic application of 18α-GA to treat the gingival overgrowth induced by PHT. Human gingival fibroblasts from healthy donors were cultured to semi-confluence and then stimulated in serum-free DMEM containing PHT with or without 18α-GA for subsequent experiments. Apoptotic cells were detected by ELISA. Analysis of the distribution of cell cycle phases and the apoptotic cell population was performed by flow cytometry. The expression levels of mRNAs and proteins of apoptotic regulators were measured using reverse transcription-quantitative PCR and western blotting, respectively. Caspase (CASP) activities were assessed by an ELISA. Treatment with 18α-GA markedly increased the number of apoptotic cells, reduced BCL2 mRNA expression, increased CASP2 and receptor (TNFRSF)-interacting serine-threonine kinase 1 (RIPK1) domain containing adaptor with death domain, Fas (TNFRSF6)-associated via death domain, RIPK1, tumor necrosis factor receptor superfamily; member 1A, TNF receptor-associated factor 2, CASP2, CASP3 and CASP9 mRNA expression, and also upregulated the protein expression levels and activities of caspase-2, caspase-3 and caspase-9. These results demonstrated that 18α-GA induced apoptosis through the activation of the Fas and TNF pathways in the death receptor signaling pathway in gingival fibroblasts treated with PHT. 18α-GA exhibited therapeutic potential for the treatment of PHT-induced gingival overgrowth.

Phenytoin Decreases Pain-like Behaviors and Improves Opioid Analgesia in a Rat Model of Neuropathic Pain

Neuropathic pain remains a clinical challenge due to its complex and not yet fully understood pathomechanism, which result in limited analgesic effectiveness of the management offered, particularly for patients with acute, refractory neuropathic pain states. In addition to the introduction of several modern therapeutic approaches, such as neuromodulation or novel anti-neuropathic drugs, significant efforts have been made in the repurposing of well-known substances such as phenytoin. Although its main mechanism of action occurs at sodium channels in excitable and non-excitable cells and is well documented, how the drug affects the disturbed neuropathic interactions at the spinal cord level and how it influences morphine-induced analgesia have not been clarified, both being crucial from a clinical perspective. We demonstrated that single and repeated systemic administrations of phenytoin decreased tactile and thermal hypersensitivity in an animal model of neuropathic pain. Importantly, we observed an increase in the antinociceptive effect on thermal stimuli with repeated administrations of phenytoin. This is the first study to report that phenytoin improves morphine-induced antinociceptive effects and influences microglia/macrophage activity at the spinal cord and dorsal root ganglion levels in a neuropathic pain model. Our findings support the hypothesis that phenytoin may represent an effective strategy for neuropathic pain management in clinical practice, particularly when combination with opioids is needed.

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.

miRNA-26-5p inhibits cyclosporine A-induced overgrowth of gingival fibroblasts by regulating PTEN/PI3K/AKT pathway

We evaluated the effect of cyclosporine A (CsA) administration on the level of miR-26-5p in rat gingival tissues and human gingival fibroblasts (HGFs) by qRT-PCR assay. Further, we conducted Western blotting and immunohistochemical analysis to assess the expressions of PTEN, PI3K, and p-AKT, and evaluated cell proliferation of HGFs by MTT assay. CsA treatment significantly downregulated the expressions of miR-26-5p and PTEN and upregulated the expressions of PI3K and p-AKT in both rat gingival tissues and HGFs. Overexpression of miR-26-5p inhibited CsA-induced overgrowth of HGFs, whereas knockdown of miR-26-5p promoted the overgrowth. PTEN knockdown not only promoted CsA-induced overgrowth of human HGFs but also reversed the repressive effects of miR-26-5p on CsA-induced overgrowth of HGFs. Our results revealed that miRNA-26-5p could repress CsA-induced overgrowth of human HGFs by regulating PTEN/PI3K/AKT pathway.

SPOCK1 is a novel inducer of epithelial to mesenchymal transition in drug-induced gingival overgrowth

Few studies have investigated the role of extracellular-matrix proteoglycans in the pathogenesis of drug-induced gingival overgrowth (DIGO). SPOCK1 is an extracellular proteoglycan that induces epithelial to mesenchymal transition (EMT) in several cancer cell lines and exhibits protease-inhibitory activity. However, the role of SPOCK1 in non-cancerous diseases such as DIGO has not been well-addressed. We demonstrated that the expression of SPOCK1, TGF-β1, and MMP-9 in calcium channel blocker-induced gingival overgrowth is higher than that in non-overgrowth tissues. Transgenic mice overexpressing Spock1 developed obvious gingival-overgrowth and fibrosis phenotypes, and positively correlated with EMT-like changes. Furthermore, in vitro data indicated a tri-directional interaction between SPOCK1, TGF-β1, and MMP-9 that led to gingival overgrowth. Our study shows that SPOCK1 up-regulation in a noncancerous disease and SPOCK1-induced EMT in gingival overgrowth occurs via cooperation and crosstalk between several potential signaling pathways. Therefore, SPOCK1 is a novel therapeutic target for gingival overgrowth and its expression is a potential risk of EMT induction in cancerous lesions.

Phenytoin sodium-ameliorated gingival fibroblast aging is associated with autophagy

BACKGROUND AND OBJECTIVE

Human gingival fibrolasts aging is an important cause of periodontal disease. Phenytoin sodium (phenytoin) has a side effect of gingival hyperplasia and an effect on the autophagy progress. This study investigated whether the effect of phenytoin on aging gingival fibroblast is related to the autophagy pathway.

MATERIAL AND METHODS

The aging model of gingival fibroblast cell line HGF-1 was induced by hydrogen peroxide (H₂ O₂ ), and the treatment of phenytoin and 3-methyladenine (3-MA) was performed simultaneously. Cell viability, cell cycle, and intracellular calcium ion were measured by flow cytometry. Changes in expression of basic fibroblast growth factor (bFGF), P16^INK4A , P21^cip1 , and bFGF, P16^INK4A , P21^cip1 , LC3II, p62, and Beclin were tested by using reverse transcription polymerase chain reaction, western blot, and immunofluorescence staining.

RESULTS

The results showed that aging HGF-1 proliferation was inhibited by H₂ O₂ , gene, protein expression of bFGF, P16^INK4A , and P21^cip1 were decreased, autophagy-related proteins LC3II, p62, and Becline were decreased, and the proportion of G0/G1 phase and intracellular calcium ion of cell cycle was increased. Phenytoin treatment could recovery above changes, but the effect of phenytoin could be blocked by 3-MA.

CONCLUSION

We propose that phenytoin alleviates the aging of gingival fibroblasts induced by H₂ O₂ . This condition is related to the enhancement of autophagy pathway.

miR-4651 inhibits cell proliferation of gingival mesenchymal stem cells by inhibiting HMGA2 under nifedipine treatment

Drug-induced gingival overgrowth (DIGO) is recognized as a side effect of nifedipine (NIF); however, the underlying molecular mechanisms remain unknown. In this study, we found that overexpressed miR-4651 inhibits cell proliferation and induces G0/G1-phase arrest in gingival mesenchymal stem cells (GMSCs) with or without NIF treatment. Furthermore, sequential window acquisition of all theoretical mass spectra (SWATH-MS) analysis, bioinformatics analysis, and dual-luciferase report assay results confirmed that high-mobility group AT-hook 2 (HMGA2) is the downstream target gene of miR-4651. Overexpression of HMGA2 enhanced GMSC proliferation and accelerated the cell cycle with or without NIF treatment. The present study demonstrates that miR-4651 inhibits the proliferation of GMSCs and arrests the cell cycle at the G0/G1 phase by upregulating cyclin D and CDK2 while downregulating cyclin E through inhibition of HMGA2 under NIF stimulation. These findings reveal a novel mechanism regulating DIGO progression and suggest the potential of miR-4651 and HMGA2 as therapeutic targets.

Nizam MN, Alshammari A. An Update on the Mechanisms of Phenytoin Induced Gingival Overgrowth

Background:

Phenytoin induced gingival overgrowth, a side effect with multifactorial aetiology, is characterized by an increase in the volume of extracellular tissues, particularly collagenous components, with varying degrees of inflammation.

Objective:

The aim of this paper is to review the available literature regarding the pathophysiological mechanisms of phenytoin induced gingival overgrowth.

Methods:

A thorough literature search of the PubMed/ Embase/ Web of science/ Cochrane central database was conducted to identify the mechanisms involved in the process of phenytoin-induced gingival overgrowth using the following keywords: Phenytoin; Anticonvulsant; Gingival Overgrowth; Gingival Enlargement, Gingival Hyperplasia; Drug Induced Gingival Enlargement; Drug Induced Gingival Overgrowth

Results:

According to the available evidence, several mechanisms have been proposed addressing the pathophysiological mechanism of phenytoin induced gingival overgrowth both at a cellular and molecular level. Evidence suggests that the inflammatory changes in the gingival tissues orchestrate the interaction between phenytoin and fibroblasts particularly resulting in an increase in the extracellular matrix content.

Conclusion:

However, the mechanism of production of inflammatory mediators is not fully understood. This, together with the high prevalence of Phenytoin induced gingival overgrowth, warrants further research in this area in order to develop treatment and preventive strategies for the management of this condition.

Periodontal Microbiological Status Influences the Occurrence of Cyclosporine-A and Tacrolimus-Induced Gingival Overgrowth

Immune suppressed renal transplant patients are more prone to developing oral tissue alterations due to medications associated with a pleiotropic set of side effects involving the oral cavity. Drug-induced gingival overgrowth (DIGO) is the most commonly encountered side effect resulting from administration of calcineurin inhibitors such as cyclosporine-A (CsA), the standard first-line treatment for graft rejection prevention in transplant patients. Pathogenesis of gingival overgrowth (GO) is determined by the interrelation between medications and a pre-existing inflammatory periodontal condition, the main modifiable risk factor. Severity of gingival hyperplasia clinical manifestation is also related to calcium channel blocker association, frequently provided in addition to pharmacological therapy of transplant recipients. Specifically, nifedipine-induced enlargements have a higher prevalence rate compared to amlodipine-induced enlargements; 47.8% and 3.3% respectively. Available epidemiological data show a gender difference in prevalence, whereby males are generally more frequently affected than females. The impact of GO on the well-being of an individual is significant, often leading to complications related to masticatory function and phonation, a side effect that may necessitate switching to the tacrolimus drug that, under a similar regimen, is associated with a low incidence of gingival lesion. Early detection and management of GO is imperative to allow patients to continue life-prolonging therapy with minimal morbidity. The purpose of this study was threefold: firstly, to determine the prevalence and incidence of GO under the administration of CsA and Tacrolimus; secondly, to assess the correlation between periodontal status before and after periodontal therapy and medications on progression or recurrence of DIGO; and finally, to analyse the effect of immunosuppressant in association to the channel blocker agents on the onset and progression of gingival enlargement. We compared seventy-two renal transplant patients, including 33 patients who were receiving CsA, of which 25% were also receiving nifedipine and 9.72% also receiving amlodipine, and 39 patients who were receiving tacrolimus, of which 37.5% were also receiving nifedipine and 5.55% also receiving amlodipine, aged between 35 and 60 years. Medical and pharmacological data were recorded for all patients. Clinical periodontal examination, in order to establish the inflammatory status and degree of gingival enlargement, was performed at baseline (T0), 3 months (T1), 6 months (T2), and 9 months (T3). All patients were subjected to periodontal treatment. Statistically significant correlation between the reduction of the mean value of periodontal indices and degree of gingival hyperplasia at the three times was revealed. The prevalence of GO in patients taking cyclosporine was higher (33.3%) in comparison with those taking tacrolimus (14.7%). In accordance with previous studies, this trial highlighted the clinical significance of the pathological substrate on stimulating drug-induced gingival lesion, confirming the key role of periodontal inflammation in pathogenesis of gingival enlargement, but did not confirm the additional effect of calcium-channel blocker drugs in inducing gingival enlargement.

The miR-3940-5p inhibits cell proliferation of gingival mesenchymal stem cells

OBJECTIVES

Drug-induced gingival overgrowth (DIGO) is a well-recognized side effect of nifedipine (NIF). However, the molecular mechanisms of DIGO are still unknown. Here, we explored the possible role of miR-3940-5p in DIGO using NIF-treated gingival mesenchymal stem cells (GMSCs).

MATERIAL AND METHODS

CFSE and cell cycle assays were used to examine cell proliferation. The alkaline phosphatase (ALP) activity assay, Alizarin Red staining, quantitative calcium analysis, and osteogenesis-related gene expression were used to examine osteo/dentinogenic differentiation.

RESULTS

The CFSE assay showed that NIF enhanced cell proliferation, and the over-expression of miR-3940-5p inhibited the proliferation of GMSCs with or without NIF stimulation. Cell cycle assays revealed that the cell cycle was arrested at the G0/G1 phase. Furthermore, it was found that the over-expression of miR-3940-5p upregulated p15^INK4b , p18^INK4c , p19^INK4d , and Cyclin A and downregulated Cyclin E in GMSCs with or without NIF treatment. In addition, the over-expression of miR-3940-5p enhanced ALP activity and mineralization in vitro and increased the expression of the osteo/dentinogenic differentiation markers DSPP and DMP1 and the key transcription factor DLX5 in GMSCs.

CONCLUSIONS

miR-3940-5p inhibited cell proliferation, enhanced the osteo/dentinogenic differentiation of GMSCs, and might play a role in DIGO as a potent agent in the treatment of nifedipine-induced gingival overgrowth.

Fibroblasts from recurrent fibrotic overgrowths reveal high rate of proliferation in vitro - findings from the study of hereditary and idiopathic gingival fibromatosis

PURPOSE

Investigate the content of fibrotic fibrils in gingival tissue and the proliferation of fibroblasts collected from recurrent and non-recurrent hereditary gingival fibromatosis (HGF) and idiopathic gingival fibromatosis (IGF).

METHODS

Gingival biopsies were collected from HGF (n = 3) and IGF (n = 3) donors with recurrent and non-recurrent gingival overgrowths and from a control group (Ctrl, n = 3). Hematoxylin staining was performed to evaluate the histomorphology of gingival tissue. Heidenhain's AZAN trichrome staining served for visualization of fibrotic fibrils in gingiva. Quantitative analysis of the content of fibrotic fibrils in gingival tissue was performed using a polarized light microscope. Proliferation was evaluated at 24 h, 48 h, and 72 h in fibroblast cultures using a cell proliferation ELISA assay based on 5-bromo-2'-deoxyuridine (BrdU).

RESULTS

Numerous blood vessels and fibroblasts were observed in recurrent overgrowths, whereas moderate blood vessels and moderate to scanty fibroblasts were detected in non-recurrent overgrowths. Heidenhain's staining revealed numerous collagen fibers in both recurrent and non-recurrent overgrowths. Quantitative analysis in a polarizing microscope showed significant accumulation of fibrotic fibrils exclusively in the overgrowths with the recurrence. In all time-points, increased proliferation of cells from all recurrent overgrowths was observed, but not from overgrowths which do not reoccur.

CONCLUSIONS

The study revealed that recurrent gingival overgrowths consist of highly fibrotic and dense connective tissue with numerous blood vessels and abundant fibroblasts. We also demonstrated that unlike fibroblasts derived from overgrowths, which did not present recurrence, fibroblasts derived from highly fibrotic and recurrent overgrowths maintain high rate of proliferation in vitro.

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.

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.

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.

Gingival Crevicular Fluid and Plasma Levels of Transglutaminase-2 and Oxidative Stress Markers in Cyclosporin A-Induced Gingival Overgrowth

BACKGROUND

Transglutaminase (TGM)-2 has been shown to contribute to fibrosis by extracellular matrix accumulation in some organs and is activated by intracellular reactive oxygen species. The aim of this study is to investigate levels of gingival crevicular fluid (GCF) and plasma TGM-2 and oxidative stress markers (OSMs) in cyclosporin A (CsA)-induced gingival overgrowth (GO).

METHODS

The study enrolled 20 healthy (H) individuals; 20 patients with gingivitis (G); 20 CsA-medicated patients with GO (CsA GO+); and 20 CsA-medicated patients without GO (CsA GO-). GCF and plasma levels of TGM-2 were analyzed by enzyme-linked immunosorbent assay. Spectrofluorometry was used to analyze thiobarbituric acid reactive substance (TBARS); ferric-reducing antioxidant power (FRAP); total oxidant status (TOS); and total antioxidant capacity (TAC).

RESULTS

GCF TGM-2 level was elevated in CsA GO+ compared with G (P = 0.048) and H (P = 0.001) groups. GCF TBARS level was elevated in CsA GO+ compared with other groups (CsA GO- group: P = 0.003; G group: P <0.001; and H group: P <0.001) and was higher in CsA GO- than in H (P = 0.048). GCF FRAP level was lower in CsA GO- than in H (P = 0.04). Both CsA GO+ and CsA GO- groups had lower GCF TOS levels than H (P <0.001 and P = 0.002) and G (P = 0.003 and P = 0.04). GCF TAC was higher in CsA GO+ than in H (P = 0.02). Plasma TGM-2 level was elevated in CsA GO+ compared with G (P = 0.048) and H (P = 0.002). Plasma FRAP level was higher in H and CsA GO- than in CsA GO+ (P = 0.008 and P = 0.02).

CONCLUSIONS

CsA use significantly alters GCF and plasma levels of TGM-2 and OSMs. TGM-2 may contribute to CsA-induced GO in CsA-treated patients by changing GCF and plasma levels of OSMs. Further studies are needed to prove causality and its direction.

Possible pharmacotherapy for nifedipine-induced gingival overgrowth: 18α-glycyrrhetinic acid inhibits human gingival fibroblast growth

BACKGROUND AND PURPOSE

This investigation aimed to establish the basis of a pharmacotherapy for nifedipine-induced gingival overgrowth. Gingival overgrowth has been attributed to the enhanced growth of gingival fibroblasts. In this study, we investigated the effects of 18-α-glycyrrhetinic acid (18α-GA) on growth, the cell cycle, and apoptosis and on the regulators of these processes in gingival fibroblasts isolated from patients who presented with nifedipine-induced gingival overgrowth.

EXPERIMENTAL APPROACH

Gingival fibroblasts were cultured in medium containing 1% FBS with/without 10 μM 18α-GA for 24 or 48 h, and the cell number, cell cycle phase distribution, relative DNA content, apoptotic cell number and morphological characteristics of the cells undergoing apoptosis were measured together with the levels of proteins that regulate these processes and the level of caspase activity.

KEY RESULTS

18α-GA significantly decreased cell numbers and significantly increased the percentage of cells in the sub-G1 and G0 /G1 phases of the cell cycle and the number of apoptotic cells. Nuclear condensation and fragmentation of cells into small apoptotic bodies appeared in the fibroblasts treated with 18α-GA. In addition, 18α-GA significantly decreased the protein levels of cyclins A and D1, CDKs 2 and 6, phosphorylated Rb (ser(780) and ser(807/811)), Bcl-xL and Bcl-2 and increased the protein levels of p27, cytosolic cytochrome c, pro-caspase-3, and cleaved caspase-3 and the activities of caspases 3 and 9.

CONCLUSIONS AND IMPLICATIONS

18α-GA inhibited gingival fibroblast growth by suppressing the G1 /S phase transition and inducing apoptosis. In conclusion, 18α-GA may be used as a pharmacotherapy for nifedipine-induced gingival overgrowth.

Cyclosporine A: Novel concepts in its role in drug-induced gingival overgrowth

Cyclosporine is a selective immunosuppressant that has a variety of applications in medical practice. Like phenytoin and the calcium channel blockers, the drug is associated with gingival overgrowth. This review considers the pharmacokinetics, pharmacodynamics, and unwanted effects of cyclosporine, in particular the action of the drug on the gingival tissues. In addition, elucidates the current concepts in mechanisms of cyclosporine-induced gingival overgrowth. Clinical and cell culture studies suggest that the mechanism of gingival overgrowth is a result of the interaction between the drug and its metabolites with susceptible gingival fibroblasts. Plaque-induced gingival inflammation appears to enhance this interaction. However, understanding of the pathogenesis of gingival overgrowth is incomplete at best. Hence, it would be pertinent to identify and explore possible risk factors relating to both prevalence and severity of drug-induced gingival overgrowth. Newer molecular approaches are needed to clearly establish the pathogenesis of gingival overgrowth and to provide novel information for the design of future preventive and therapeutic modalities.

Phenytoin enhances the phosphorylation of epidermal growth factor receptor and fibroblast growth factor receptor in the subventricular zone and promotes the proliferation of neural precursor cells and oligodendrocyte differentiation

Phenytoin is a widely used antiepileptic drug that induces cell proliferation in several tissues, such as heart, bone, skin, oral mucosa and neural precursors. Some of these effects are mediated via fibroblast growth factor receptor (FGFR) and epidermal growth factor receptor (EGFR). These receptors are strongly expressed in the adult ventricular-subventricular zone (V-SVZ), the main neurogenic niche in the adult brain. The aim of this study was to determine the cell lineage and cell fate of V-SVZ neural progenitors expanded by phenytoin, as well as the effects of this drug on EGFR/FGFR phosphorylation. Male BALB/C mice received 10 mg/kg phenytoin by oral cannula for 30 days. We analysed the proliferation of V-SVZ neural progenitors by immunohistochemistry and western blot. Our findings indicate that phenytoin enhanced twofold the phosphorylation of EGFR and FGFR in the V-SVZ, increased the number of bromodeoxyuridine (BrdU)+/Sox2+ and BrdU+/doublecortin+ cells in the V-SVZ, and expanded the population of Olig2-expressing cells around the lateral ventricles. After phenytoin removal, a large number of BrdU+/Receptor interacting protein (RIP)+ cells were observed in the olfactory bulb. In conclusion, phenytoin enhanced the phosphorylation of FGFR and EGFR, and promoted the expression of neural precursor markers in the V-SVZ. In parallel, the number of oligodendrocytes increased significantly after phenytoin removal.

Nifedipine and phenytoin induce matrix synthesis, but not proliferation, in intact human gingival connective tissue ex vivo

Drug-induced gingival enlargement (DIGE) is a fibrotic condition that can be caused by the antihypertensive drug nifedipine and the anti-seizure drug phenytoin, but the molecular etiology of this type of fibrosis is not well understood and the role of confounding factors such as inflammation remains to be fully investigated. The aim of this study was to develop an ex vivo gingival explant system to allow investigation of the effects of nifedipine and phenytoin alone on human gingival tissue. Comparisons were made to the histology of human DIGE tissue retrieved from individuals with DIGE. Increased collagen, fibronectin, and proliferating fibroblasts were evident, but myofibroblasts were not detected in DIGE samples caused by nifedipine and phenytoin. In healthy gingiva cultured in nifedipine or phenytoin-containing media, the number of cells positive for p-SMAD2/3 increased, concomitant with increased CCN2 and periostin immunoreactivity compared to untreated explants. Collagen content assessed through hydroxyproline assays was significantly higher in tissues cultured with either drug compared to control tissues, which was confirmed histologically. Matrix fibronectin levels were also qualitatively greater in tissues treated with either drug. No significant differences in proliferating cells were observed between any of the conditions. Our study demonstrates that nifedipine and phenytoin activate canonical transforming growth factor-beta signaling, CCN2 and periostin expression, as well as increase collagen density, but do not influence cell proliferation or induce myofibroblast differentiation. We conclude that in the absence of confounding variables, nifedipine and phenytoin alter matrix homeostasis in gingival tissue explants ex vivo, and drug administration is a significant factor influencing ECM accumulation in gingival enlargement.

Molecular and clinical aspects of drug-induced gingival overgrowth

Drug-induced gingival overgrowth is a tissue-specific condition and is estimated to affect approximately one million North Americans. Lesions occur principally as side-effects from phenytoin, nifedipine, or ciclosporin therapy in approximately half of the people who take these agents. Due to new indications for these drugs, their use continues to grow. Here, we review the molecular and cellular characteristics of human gingival overgrowth lesions and highlight how they differ considerably as a function of the causative drug. Analyses of molecular signaling pathways in cultured human gingival fibroblasts have provided evidence for their unique aspects compared with fibroblasts from the lung and kidney. These findings provide insights into both the basis for tissue specificity and into possible therapeutic opportunities which are reviewed here. Although ciclosporin-induced gingival overgrowth lesions exhibit principally the presence of inflammation and little fibrosis, nifedipine- and especially phenytoin-induced lesions are highly fibrotic. The increased expression of markers of gingival fibrosis, particularly CCN2 [also known as connective tissue growth factor (CTGF)], markers of epithelial to mesenchymal transition, and more recently periostin and members of the lysyl oxidase family of enzymes have been documented in phenytoin or nifedipine lesions. Some oral fibrotic conditions such as leukoplakia and oral submucous fibrosis, after subsequent additional genetic damage, can develop into oral cancer. Since many pathways are shared, the study of gingival fibrosis and comparisons with characteristics and molecular drivers of oral cancer would likely enhance understandings and functional roles of molecular drivers of these oral pathologies.

Ocular findings in syndromic gingival fibromatosis: a case study and electronic microscopic investigation of lens

We report a case of syndromic gingival fibromatosis with notable ocular lesions, bilateral congenital cataracts, esotropia, and high myopia of a 21-year-old male patient from China. The patient was diagnosed with gingival fibromatosis based on his massive gingival overgrowth and histological findings that were consistent with gingival fibromatosis through a gingival biopsy. Lens opacity features were presented and phacoemulsificaion with intraocular lens(IOL) implantation was performed to manage the cataracts in both eyes. Transmission electronic microscopy was used to investigate the ultrastructure of the removed lens tissue. We also review the literature on gingival fibromatosis and briefly summarize the ocular manifestations of this rare disease.

Serum cyclophilin A concentrations in renal transplant recipients receiving cyclosporine A: clinical implications for gingival overgrowth

OBJECTIVE

The aim of this study was to investigate the clinical factors in relation to the cyclosporine A (CsA) induced gingival overgrowth (GO).

STUDY DESIGN

Seventy-three participants were assigned as GO+ and GO-. Factors including demographic, pharmacological, gingival variables and the serum cyclophilin A (CyPA) concentration were analyzed.

RESULTS

The occurrence of GO was 39.72%. Papillary bleeding index (PBI) had a significantly higher risk of GO than plaque index (PI), the ratio of CsA to CyPA, and serum CyPA concentration (odds ratio = 364.323, 25.791, 1.002, 0.096, respectively). The severity of GO correlated with PI, the ratio of CsA to CyPA, PBI, serum concentrations of CsA and CyPA (r = 0.366, 0.355, 0.344, 0.305, and -0.232, respectively).

CONCLUSIONS

Since a cross-sectional study is not able to explain whether plaque and inflammation are the cause or consequence of GO, the ratio of CsA to CyPA may be a valuable marker for predicting GO.

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.

Gingival fibromatosis with multiple unusual findings: report of a rare case

Gingival fibromatosis is a rare disease, especially its syndromic form. Here, we review the literatures on gingival fibromatosis and briefly summarize some characters on clinical, etiological, genetic and histopathological aspects. We also present a rare case of gingival fibromatosis with multiple unusual findings in a 21-year-old man. And we differentiate it from some well-known syndromes including gingival fibromatosis. Maybe it implies a new syndrome within the spectrum of those including gingival fibromatosis.

Inhibition of G₁ cell cycle arrest in human gingival fibroblasts exposed to phenytoin

Gingival overgrowth is caused in response to the antiepileptic drug phenytoin (PHT). PHT-induced gingival overgrowth is characterized by the proliferation of fibroblasts and increased collagen formation in gingiva. Fibroblast proliferation is regulated through the cell cycle. Thus, in the present study, we examined the effects of PHT on the cell cycle, the expression of cell cycle control proteins and the proliferation in human gingival fibroblasts (hGFs). Cells were stimulated in serum-free DMEM with or without 0.25 μm PHT. Subsequently, the cell cycle phase distribution and the protein expression after 24 h and the cell proliferation after 24, 48 and 72 h were evaluated. PHT significantly inhibited synchronization at the G₀/G₁ phase of the cell cycle in hGFs through serum starvation. Stimulation with PHT for 48 and 72 h significantly induced a proliferative response in hGFs. PHT decreased the expression of the Cdk-inhibitory proteins p21 and p27 and increased the levels of the S phase-promoting proteins phospho-Thr160-Cdk2 and phospho-Ser807/811-Rb in serum-free DMEM. The inhibition of G₁ cell cycle arrest in hGFs may result from an increase in phosphorylated Cdk2 and Rb proteins and decreased levels of p21 and p27 proteins by PHT. The gingival overgrowth may be caused by the failure of the G1 cell cycle arrest in GFs exposed to PHT.

Recombinant lysyl oxidase propeptide protein inhibits growth and promotes apoptosis of pre-existing murine breast cancer xenografts

Lysyl oxidase propeptide (LOX-PP) ectopic overexpression inhibits the growth of cancer xenografts. Here the ability and mode of action of purified recombinant LOX-PP (rLOX-PP) protein to inhibit the growth of pre-existing xenografts was determined. Experimental approaches employed were direct intratumoral injection (i.t.) of rLOX-PP protein into murine breast cancer NF639 xenografts, and application of a slow release formulation of rLOX-PP implanted adjacent to tumors in NCR nu/nu mice (n = 10). Tumors were monitored for growth, and after sacrifice were subjected to immunohistochemical and Western blot analyses for several markers of proliferation, apoptosis, and for rLOX-PP itself. Direct i.t. injection of rLOX-PP significantly reduced tumor volume on days 20, 22 and 25 and tumor weight at harvest on day 25 by 30% compared to control. Implantation of beads preloaded with 35 micrograms rLOX-PP (n = 10) in vivo reduced tumor volume and weight at sacrifice when compared to empty beads (p<0.05). A 30% reduction of tumor volume on days 22 and 25 (p<0.05) and final tumor weight on day 25 (p<0.05) were observed with a reduced tumor growth rate of 60% after implantation. rLOX-PP significantly reduced the expression of proliferation markers and Erk1/2 MAP kinase activation, while prominent increases in apoptosis markers were observed. rLOX-PP was detected by immunohistochemistry in harvested rLOX-PP tumors, but not in controls. Data provide pre-clinical findings that support proof of principle for the therapeutic anti-cancer potential of rLOX-PP protein formulations.

Diphenylhydantoin promotes proliferation in the subventricular zone and dentate gyrus

PROBLEM STATEMENT

Diphenylhydantoin (phenytoin) is an antiepileptic drug that generates hyperplasia in some tissue by stimulating Epidermal Growth Factor (EGFR) and Platelet-Derived Growth Factor beta (PDGFR-β) receptors and by increasing serum levels of basic fibroblast growth factor (bFGF, FGF2 or FGF-β). Neural stem cells in the adult brain have been isolated from three regions: the Subventricular Zone (SVZ) lining the lateral wall of the lateral ventricles, the Subgranular Zone (SGZ) in the dentate gyrus at the hippocampus and the Subgranular Zone (SZC) lining between the hippocampus and the corpus callosum. Neural stem cells actively respond to bFGF, PDGFR-β or EGF by increasing their proliferation, survival and differentiation. The aim of this study was to evaluate the effect of phenytoin on proliferation and apoptosis in the three neurogenic niches in the adult brain.

APPROACH

We orally administrated phenytoin with an oropharyngeal cannula for 30 days: 0 mg kg^-1 (controls), 1, 5, 10, 50 and 100 mg kg^-1. To label proliferative cells, three injections of 100 mg kg^-1 of BrdU was administrated every 12 h. Immunohistochemistry against BrdU or Caspase-3 active were performed to determine the number of proliferative or apoptotic cells.

RESULTS

Our results showed that phenytoin induces proliferation in the SVZ and the SGZ in a dose-dependent manner. No statistically significant effects on cell proliferation in the SCZ neither in the apoptosis rate at the SVZ, SGZ and SCZ were found.

CONCLUSION

These data indicate that phenytoin promotes a dose-dependent proliferation in the SVZ and SGZ of the adult brain. The clinical relevance of these findings remain to be elucidated.

Phenytoin-induced gingival overgrowth: a review of the molecular, immune, and inflammatory features

Gingival overgrowth (GO) is a side effect associated with some distinct classes of drugs, such as anticonvulsants, immunosuppressant, and calcium channel blockers. GO is characterized by the accumulation of extracellular matrix in gingival connective tissues, particularly collagenous components, with varying degrees of inflammation. One of the main drugs associated with GO is the antiepileptic phenytoin, which affects gingival tissues by altering extracellular matrix metabolism. Nevertheless, the pathogenesis of such drug-induced GO remains fulfilled by some contradictory findings. This paper aims to present the most relevant studies regarding the molecular, immune, and inflammatory aspects of phenytoin-induced gingival overgrowth.

Reduction in lipopolysaccharide-induced apoptosis of fibroblasts obtained from a patient with gingival overgrowth during nifedipine-treatment

OBJECTIVE

We have previously demonstrated that the mechanism of nifedipine (NIF)-induced gingival overgrowth is related to the observation that proliferation and cell cycle progression of gingival fibroblasts derived from NIF reactive patient (NIFr) are greater than those from NIF non-reactive patient (NIFn). Gingival overgrowth has also been reported to be a result of inhibited apoptosis of gingival fibroblasts. Apoptosis in fibroblasts is induced by lipopolysaccharide (LPS). Thus, we focused upon evaluating whether there is a difference in LPS-induced apoptosis between NIFn and NIFr.

METHODS

Both NIFn and NIFr were arrested in DMEM containing 0.5% FBS, stimulated by LPS, and assayed for apoptosis, cell cycle analysis, Western blotting, and caspase activity.

RESULTS

Compared to NIFn, the number of apoptotic cells was significantly decreased and the percentage of cells in S and G(2)/M phase was significantly increased in NIFr. The levels of Bax and cytochrome c proteins in NIFr were not up-regulated by LPS compared with NIFn. Both NIFn and NIFr displayed the following changes in protein expression: increased Bad, decreased Bcl-xL, and unchanged Bcl-2 and p53. Caspase-3 and -9 activities were significantly increased by LPS in NIFn but were unchanged in NIFr. Caspase-2 activity remained constant whilst caspase-8 activity significantly increased upon LPS treatment in both NIFn and NIFr.

CONCLUSION

Bad, Bax, cytochrome c, p53, and caspases-2, -3, -8, and -9 are pro-apoptotic proteins. Bcl-2 and Bcl-xL are anti-apoptotic proteins. Thus, the mechanism of NIF-induced gingival overgrowth might be related to decreased apoptosis in NIFr through a reduction of Bax, cytochrome c, and caspase-3 and -9.

Minichromosome maintenance 2 and 5 expressions are increased in the epithelium of hereditary gingival fibromatosis associated with dental abnormalities

INTRODUCTION

Gingiva fibromatosis is a relatively rare condition characterized by diffuse enlargement of the gingiva, which is caused by expansion and accumulation of the connective tissue.

OBJECTIVE

The aim of the present study was to investigate proliferative and apoptotic biomarker expression in normal gingiva and two forms of gingival fibromatosis.

METHODS

Archived tissue specimens of hereditary gingival fibromatosis, gingival fibromatosis and dental abnormality syndrome and normal gingiva were subject to morphological analysis and immunohistochemical staining. The results were analyzed statistically.

RESULTS

Proteins associated with proliferation were found in the nuclei of epithelial cells from the basal and suprabasal layers, whereas apoptotic proteins were detected in the cytoplasm of the upper layers of the epithelium. Increased expressions of minichromosome maintenance proteins 2 and 5 were observed in the gingival fibromatosis and dental abnormality syndrome samples. In contrast, geminin expression was higher in normal gingiva samples. No difference in the expression of apoptotic proteins was observed among the groups.

CONCLUSION

Our findings support a role for augmented proliferation of epithelial cells within the overgrown tissues associated with gingival fibromatosis or dental abnormality syndrome. However, our data suggest that different biological mechanisms may account for the pathogenesis of different types of gingival fibromatosis.

GCF and serum myeloperoxidase and matrix metalloproteinase-13 levels in renal transplant patients

AIM

The rationale of this study was to address whether local or systemic changes reflect proteolytic (matrix metalloproteinase-13) or oxidative (myeloperoxidase) stress in renal transplant patients receiving cyclosporine-A (CsA) and having gingival overgrowth (GO), in patients receiving CsA therapy and having no GO and patients receiving tacrolimus therapy.

MATERIAL AND METHODS

Gingival crevicular fluid (GCF) samples were collected from sites with (GO+) and without GO (GO-) in CsA patients having GO; GO- sites in CsA patients having no GO; sites from tacrolimus, gingivitis and healthy subjects. GCF and serum myeloperoxidase (MPO) and matrix metalloproteinase-13 (MMP-13) levels were determined by ELISA.

RESULTS

GO+ sites in CsA patients having GO had elevated GCF MPO levels than those of CsA patients having no GO, tacrolimus and healthy subjects (p<0.005), but comparable to those of gingivitis. GCF MPO levels were higher in GO+ compared to GO- sites in CsA patients having GO (p<0.05). Patient groups had similar, but higher GCF MMP-13 levels than healthy group.

CONCLUSIONS

These results show that CsA and tacrolimus therapy have not a significant effect on GCF MPO and MMP-13 levels, and gingival inflammation seems to be the main reason for their elevations.

Altered fibroblast proliferation and apoptosis in diabetic gingival wounds

Although it is known that diabetes impairs oral wound healing, relatively little is known about the cellular parameters affected, particularly in connective tissue. This study investigated the hypothesis that diabetes impairs connective tissue formation in healing gingiva, and that impaired healing is associated with factors that decrease fibroblast numbers. Full-thickness wounds were created in the palatal gingiva of type 1 and type 2 diabetic and normoglycemic mice. Five days after wounding, diabetic mice had less epithelial wound coverage, less new connective tissue formation, and reduced fibroblast density (p < 0.05). This occurred with increased numbers of caspase-3- and TUNEL-positive fibroblasts, decreased fibroblast proliferation, increased nuclear translocation of the pro-apoptotic transcription factor FOXO1, and increased numbers of polymorphonuclear leukocytes, all of which were significant (p < 0.05). The results suggest that diabetes may decrease fibroblast numbers through increased apoptosis and reduced proliferation, both of which may be mediated through increased activation of FOXO1.

Cyclosporin A and phenytoin modulate inflammatory responses

Gingival overgrowth is a common side-effect of administration of the immunosuppressant cyclosporin A and the anti-epileptic drug phenytoin. While cyclosporin-induced gingival overgrowth is often accompanied by gingival inflammation, phenytoin-induced gingival overgrowth usually forms fibrotic lesions. To determine whether these drugs alter the inflammatory responses of gingival fibroblasts, we investigated the effects of cyclosporin and phenytoin on Toll-like receptor (TLR)-mediated responses to microbial components. In Chinese hamster ovary reporter cell lines, cyclosporin alone triggered signaling, whereas phenytoin down-regulated signaling induced by the TLR2 or TLR4 ligand. In human gingival fibroblasts, cyclosporin alone did not induce evident inflammatory responses, but augmented the expression of CD54 and the production of interleukin (IL)-6 and IL-8 induced by TLR ligands, whereas phenytoin attenuated those responses. Cyclosporin also augmented CD54 expression in gingiva of mice injected with lipopolysaccharide. These results indicated that cyclosporin positively and phenytoin negatively modulated inflammatory responses of human gingival fibroblasts.

Inhibition of apoptotic signals in overgrowth of human gingival fibroblasts by cyclosporin A treatment

Cyclosporin A (CsA), an immunosuppressive drug, has overgrowth effects on human gingival fibroblasts (HGF) in vitro. However, the molecular mechanism responsible for the CsA-induced gingival overgrowth remains still unclear. The present study is aimed to investigate the correlation with the apoptotic signal pathway in CsA-induced overgrowth of HGF. CsA-treated HGF were assessed for cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, for reactive oxygen species (ROS) detection by flow cytometry, for proliferation ability using the 5-bromo-20-deoxyuridine (BrdU), for caspase activities biochemically, for expression of apoptotic signal molecules such as cytochrome c, Fas and Fas-L and Bcl-2 family by Western blotting and VDAC by RT-PCR. CsA increased the cell viability, but not the number of BrdU-positive HGF, indicating that CsA fails to induce the proliferation of HGF. CsA also decreased the intracellular reactive oxygen species level in HGF. This was accompanied by that the antiapoptotic protein Bcl-2 was upregulated whereas the proapoptotic protein Bax was downregulated. Moreover, CsA downregulated VDAC, a mitochondrial transition pore, and decreased the level of cytochrome c released from the mitochondria into the cytosol and activation of caspase-3 and -9 associated with mitochondria-mediated apoptosis. On the other hand, Fas-L level and caspase-8 activation, the major mediator of the death receptor-mediated apoptosis, were diminished in the CsA-treated HGF. CsA inhibits the apoptotic signal molecules such as cytochrome c, caspases and Fas-L with the regulation of Bcl-2 family whereas it has no effect on cell division, which can contribute to overgrowth of HGF. These findings suggest that the decreased apoptosis plays a more important role than the increased cell proliferation in the CsA-induced overgrowth of HGF.

Gingival crevicular fluid transforming growth factor-beta1 in cyclosporine and tacrolimus treated renal transplant patients without gingival overgrowth

BACKGROUND

Gingival crevicular fluid (GCF) levels of transforming growth factor-beta(1) (TGF-beta(1)) have been previously investigated in relation to the pathogenesis of cyclosporine-A (CsA)-induced gingival overgrowth (GO) but no clinical data are available regarding the GCF levels of TGF-beta(1) in patients treated with tacrolimus (Tac). However, as gingival inflammation is pronounced at sites of GO and this consequently may lead to an elevation in TGF-beta(1) levels the present study aimed to evaluate gingival crevicular fluid (GCF) TGF-beta(1) levels in renal transplant patients using CsA or Tac without GO.

METHODS

GCF TGF-beta(1) levels were investigated in 30 renal transplant patients without GO medicated with either CsA (n=15) or Tac (n=15). Sixteen gingivitis patients and 15 periodontally healthy subjects were selected as controls. Periodontal status was evaluated by measuring probing depth, plaque index and papilla bleeding index. The TGF-beta(1) levels were analysed by enzyme-linked immunosorbent assay.

RESULTS

Both CsA and Tac groups had significantly elevated GCF TGF-beta(1) total amount compared to gingivitis and healthy groups (p<0.008). GCF TGF-beta(1) total amount of CsA and Tac groups was similar (p>0.008). Gingivitis and healthy groups had also similar GCF TGF-beta(1) total amount (p>0.008).

CONCLUSIONS

Within the limits of the present data it is unlikely that TGF-beta(1) is an exclusive mediator of CsA- or Tac-induced GO. However, pathogenesis of GO is multifactorial and contribution of TGF-beta(1) to the interrelations between cytokines and growth factors with fibrogenic potential cannot be disregarded.