Growth factors and proliferation of cultured rat gingival cells in response to cyclosporin A

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.

Drug-Induced Gingival Overgrowth: The Effect of Cyclosporin A and Mycophenolate Mophetil on Human Gingival Fibroblasts

Drug-induced gingival overgrowth may occur after a chronic administration of three classes of systemic drugs: Anticonvulsants, immunosuppressants, and calcium channel blockers. This study aimed to investigate how cyclosporin A and mycophenolate mophetil (immunosuppressive drugs) could interfere with human gingival fibroblasts functions, leading to gingival enlargement. Human gingival fibroblasts derived from the tissue of a 60-year-old female were cultured in a DMEME medium. A stock solution with 1 mg/mL of mycophenolate and 1 mg/mL of cyclosporine were prepared and dissolved in a DMEM medium to prepare a serial dilution at the concentrations of 5000, 2000, 1000, 500, and 100 ng/mL, for both treatments. Cell viability was measured using the PrestoBlue™ Reagent Protocol. Quantitative real-time RT-PCR was performed in order to analyze the expression of 57 genes coding for gingival fibroblasts "Extracellular Matrix and Adhesion Molecules". Mycophenolate and cyclosporine had no effect on fibroblast cell viability at 1000 ng/mL. Both the treatments showed similar effects on the expression profiling of treated cells: Downregulation of most extracellular matrix metalloproteases genes (MMP8, MMP11, MMP15, MMP16, MMP24) was assessed, while CDH1, ITGA2, ITGA7, LAMB3, MMP12, and MMP13 were recorded to be upregulated in fibroblasts treated with immunosuppressive drugs. It has been demonstrated that gingival overgrowth can be caused by the chronic administration of cyclosporin A and mycophenolate mophetil. However, given the contrasting data of literature, further investigations are needed, making clear the possible effects of immunosuppressive drugs on fibroblasts.

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.

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.

Role of Shh and TGF in cyclosporine-enhanced expression of collagen and α-SMA by gingival fibroblast

OBJECTIVE

Cyclosporine-A (CsA)-induced gingival overgrowth may arise from an alteration in stoma matrix homeostasis. Sonic hedgehog (Shh) plays a key role during embryogenic development and fibrotic progression, and may be involved in CsA-altered gingival matrix homeostasis.

METHODS

Using the reverse transcription-polymerase chain reaction and Western blot analysis, we investigated the mRNA and protein expressions of Shh, type 1 collagen (COL1), alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta (TGF-β) in human gingival fibroblasts after CsA treatments. The effect of Shh on CsA-induced alterations was further evaluated by the extra-supplement or inhibition of Shh or TGF-β.

RESULTS

Cyclosporine-A enhanced COL1, α-SMA, Shh and TGF-β expressions in human gingival fibroblasts. The exogenous Shh/TGF-β augmented the expression of COL1 and α-SMA, and the Shh/TGF-β inhibition suppressed the CsA-enhanced COL1 and α-SMA expressions. Moreover, Shh mRNA and protein expressions increased if extra-supplementing the exogenous TGF-β, whereas the CsA-upregulated Shh was mitigated by the TGF-β pathway inhibitor. However, neither exogenous Shh nor the Shh pathway inhibitor alters TGF-β expression or CsA-up-regulated TGF-β expression.

CONCLUSIONS

Shh, regulated by TGF-β, mediates CsA-altered gingival matrix homeostasis.

Cyclosporine A up-regulates Sonic hedgehog in gingiva: role of the up-regulation on gingival cell proliferation

BACKGROUND AND OBJECTIVE

Sonic hedgehog protein (SHH) is a mitogen that stimulates cell proliferation. Cyclosporine A enhances the proliferation of gingival cells; however, the relationships of SHH to cyclosporine A or to cyclosporine A-enhanced gingival cell proliferation have not been described.

MATERIAL AND METHODS

Here, we investigated SHH expression in gingiva in vitro and in vivo after cyclosporine A treatment and tested the effect of SHH inhibition on cyclosporine A-enhanced gingival fibroblast proliferation in vitro.

RESULTS

In human gingival fibroblasts, cyclosporine A treatment increased the expression of SHH transcripts and SHH protein, and stimulated cell proliferation; the addition of cyclopamine, an SHH signaling inhibitor, suppressed cyclosporine A-enhanced cell proliferation. Up-regulated expression of SHH and up-regulation of proliferating cell nuclear antigen transcripts and protein were observed in the edentulous gingiva of cyclosporine A-treated rats.

CONCLUSION

Cyclosporine A up-regulates gingival SHH expression in vitro and in vivo, and the inhibition of the SHH pathway counteracts the stimulatory effect of cyclosporine A on gingival fibroblast proliferation. Therefore, we suggest that SHH mediates a novel molecular mechanism for cyclosporine A-induced gingival complications.

Crosstalk between Shh and TGF-β signaling in cyclosporine-enhanced cell proliferation in human gingival fibroblasts

BACKGROUND

Immunosuppressant cyclosporine-A induces gingival hyperplasia, which is characterized by increased fibroblast proliferation and overproduction of extracellular matrix components and regulated by transforming growth factor-beta (TGF-β). The TGF-β and Sonic hedgehog (Shh) pathways both mediate cell proliferation. Crosstalk between these pathways in cancer has recently been proposed, but the hierarchical pattern of this crosstalk remains unclear. In normal fibroblasts, a TGF-β-stimulating Shh pattern was observed in induced fibrosis. However, Shh pathway involvement in cyclosporine-enhanced gingival proliferation and the existence of crosstalk with the TGF-β pathway remain unclear.

METHODOLOGY/PRINCIPAL FINDINGS

Cyclosporine enhanced mRNA and protein levels of TGF-β and Shh in human gingival fibroblasts (RT-PCR and western blotting). A TGF-β pathway inhibitor mitigated cyclosporine-enhanced cell proliferation and an Shh pathway inhibitor attenuated cyclosporine-enhanced proliferation in fibroblasts (MTS assay and/or RT-PCR of PCNA). Exogenous TGF-β increased Shh expression; however, exogenous Shh did not alter TGF-β expression. The TGF-β pathway inhibitor mitigated cyclosporine-upregulated Shh expression, but the Shh pathway inhibitor did not alter cyclosporine-upregulated TGF-β expression.

CONCLUSIONS/SIGNIFICANCE

The TGF-β and Shh pathways mediate cyclosporine-enhanced gingival fibroblast proliferation. Exogenous TGF-β increased Shh expression, and inhibition of TGF-β signaling abrogated the cyclosporine-induced upregulation of Shh expression; however, TGF-β expression appeared unchanged by enhanced or inhibited Shh signaling. This is the first study demonstrating the role of Shh in cyclosporine-enhanced gingival cell proliferation; moreover, it defines a hierarchical crosstalk pattern in which TGF-β regulates Shh in gingival fibroblasts. Understanding the regulation of cyclosporine-related Shh and TGF-β signaling and crosstalk in gingival overgrowth will clarify the mechanism of cyclosporine-induced gingival enlargement and help develop targeted therapeutics for blocking these pathways, which can be applied in pre-clinical and clinical settings.

Proliferative and inductive effects of Cyclosporine a on gingival fibroblast of child and adult

Background:

Gingival overgrowth is a serious side-effect that accompanies the use of Cyclosporin A (CsA). Up to 97% of the transplant recipient children, who were submitted to CsA therapy, have been reported to suffer from this side-effect. Several conflicting theories have been proposed to explain the fibroblast's function in CsA-induced gingival overgrowth. The aim of this study is to assess the proliferation of gingival fibroblasts and levels of released cytokines after being exposed to CsA, in both adults and pediatric groups, and to make a comparison between the results of the two groups.

Materials and Methods:

The adult fibroblast samples were derived from four healthy adults, aged 35 to 42 years and pediatric samples were obtained from four healthy children, age between four and eleven years. Tissue samples were plated in Dulbecco's Modified Eagle Medium (DMEM) containing 10% fetal bovine serum (FBS), Streptomycin and Penicillin. The samples were cultured in 25 cm² plates containing 5% CO2, and incubated at 37°C. The cells used for all the experiments were at the fourth passage. The concentration of PGE₂, IL-1β, IL-6, IL-8, TNF-α, and TGF-β₁ was determined by the enzyme-linked immunosorbent assay (ELISA) and the proliferation rate was assessed by the MTT assay. Alpha error levels were set as 0.05.

Results:

CsA stimulated significantly higher levels of IL-6, IL-8 and TGF-β₁ in adult gingival fibroblasts than it did in the control group; whereas, the expression of IL-1β and PGE₂ in the fibroblasts exposed to CsA was significantly weaker (P < 0.05). The fibroblasts in the two groups did not reveal any noticeable difference in the production of TNF-α. Furthermore, cell proliferation in the CsA group was not significantly higher than that in the control group. No significant differences in cytokines TNF-α and IL-1β were noted between the two groups. The results indicated that CsA stimulated cell proliferation in the pediatric fibroblast cell line. Comparison between the results in the adult and pediatric groups demonstrated that the levels of IL-1β, IL-6, IL-8, and PGE₂ were significantly higher in the pediatric group than in the adult group; however, statistics showed no significant difference in the levels of TNF-α and TGF-β₁ and CsA-induced proliferation between these two groups.

Conclusions:

The mechanism of a CsA-induced fibroblast overgrowth may converge on the steps involving fibroblast proliferation and cytokine network including IL-6, IL-8, IL-1β, TGF-β₁, and PGE₂, in both adults and pediatrics. As the prevalence and intensity of drug-induced gingival overgrowth is more serious in the pediatrics. As group than in adults, we suggest that more studies be conducted on the pediatric group.

The possible potential therapeutic targets for drug induced gingival overgrowth

Gingival overgrowth is a side effect of certain medications. The most fibrotic drug-induced lesions develop in response to therapy with phenytoin, the least fibrotic lesions are caused by cyclosporin A, and the intermediate fibrosis occurs in nifedipine-induced gingival overgrowth. Fibrosis is one of the largest groups of diseases for which there is no therapy but is believed to occur because of a persistent tissue repair program. During connective tissue repair, activated gingival fibroblasts synthesize and remodel newly created extracellular matrix. Proteins such as transforming growth factor (TGF), endothelin-1 (ET-1), angiotensin II (Ang II), connective tissue growth factor (CCN2/CTGF), insulin-like growth factor (IGF), and platelet-derived growth factor (PDGF) appear to act in a network that contributes to the development of gingival fibrosis. Since inflammation is the prerequisite for gingival overgrowth, mast cells and its protease enzymes also play a vital role in the pathogenesis of gingival fibrosis. Drugs targeting these proteins are currently under consideration as antifibrotic treatments. This review summarizes recent observations concerning the contribution of TGF-β, CTGF, IGF, PDGF, ET-1, Ang II, and mast cell chymase and tryptase enzymes to fibroblast activation in gingival fibrosis and the potential utility of agents blocking these proteins in affecting the outcome of drug-induced gingival overgrowth.

The upregulation of transglutaminase-2 by cyclosporin a in human gingival fibroblasts is augmented by oxidative stress

BACKGROUND

Transglutaminase-2 (TGM-2) has been implicated in several fibrotic disorders and can be induced by reactive oxygen species (ROS). Hence, the authors hypothesize that cyclosporin A (CsA) may regulate TGM-2 via ROS, and this regulation may have a role in the pathogenesis of CsA-induced gingival overgrowth.

METHODS

Cytotoxicity, 2',7'-dichlorodihydrofluorescein diacetate assay, and Western blot were used to investigate the effects of CsA in human gingival fibroblasts (HGFs). In addition, extracellular signal-regulated kinase (ERK) inhibitor PD98059, phosphatidylinositol 3-kinase inhibitor LY294002, glutathione precursor N-acetyl-L-cysteine (NAC), curcumin, epigallocatechin-3 gallate (EGCG), and p38 inhibitor SB203580 were added to find the possible regulatory mechanisms.

RESULTS

Concentrations of CsA >500 ng/mL demonstrated cytotoxicity to HGFs (P < 0.05). CsA enhanced the generation of intracellular ROS at concentrations >200 ng/mL (P <0.05). TGM-2 protein induced by CsA was found in HGFs in a dose- and time-dependent manner (P <0.05). The addition of PD98059, LY294002, NAC, curcumin, EGCG, and SB203580 markedly inhibited TGM-2 expression induced by CsA (P <0.05).

CONCLUSIONS

These results demonstrate that CsA significantly upregulates intracellular ROS generation and elevates TGM-2 expression in HGFs. In addition, TGM-2 induced by CsA is downregulated by PD98059, LY294002, NAC, curcumin, EGCG, and SB203580.

The function of platelet-derived growth factor in the differentiation of mouse tongue striated muscle

OBJECTIVE

To determine the function of platelet-derived growth factor (PDGF) in the final differentiation phase of tongue striated muscle cells.

MATERIALS AND METHODS

We analyzed the expressions of PDGF-A, -B, platelet-derived growth factor receptor (PDGFR)-α, and PDGFR-β in mouse tongues between embryonic days (E) 11 and 15. Furthermore, we examined the effects of human recombinant PDGF-AB and the peptide antagonist for PDGFRs using an organ culture system of mouse embryonic tongue. Mouse tongues at E12 were cultured in BGJb medium containing human recombinant PDGF-AB for 4 days or the peptide antagonist for PDGF receptors for 8 days.

RESULTS

PDGF-A, -B, PDGFR-α, and -β were expressed in the differentiating muscle cells between E11 and 15. The human recombinant PDGF-AB induced increases in the mRNA expressions of myogenin and muscle creatine kinase (MCK) and the number of fast myosin heavy chain (fMHC)-positive cells, markers for the differentiation of muscle cells. On the other hand, the peptide antagonist for PDGFRs induced suppressions in the mRNA expressions of myogenin and MCK, and the number of fMHC-positive cells. Both the PDGF-AB and the antagonist failed to affect the expressions of cell proliferation markers.

CONCLUSION

These results suggest that PDGF functions as a positive regulator in the final differentiation phase of tongue muscle cells in mouse embryos.

TGF-β1 gene polymorphism in renal transplant patients with and without gingival overgrowth

BACKGROUND

The incidence of gingival overgrowth among renal transplant patients treated with cyclosporine A ranges from 13% to 84.6%, and the overgrowth is not only esthetic but also a medical problem. We studied the determination of association between TGF-β1 (TGFB1) gene polymorphism and gingival overgrowth in kidney transplant patients medicated with cyclosporin A.

METHODS

Eighty-four kidney transplant patients with gingival overgrowth and 140 control transplant patients without overgrowth were enrolled into the case control study. TGFB1 polymorphism was determined using the PCR-RFLP assay for +869T > C in codon 10 and +915G > C in codon 25 as well as TaqMan real-time PCR assays for promoter -800G>A and -509C > T SNPs.

RESULTS

In kidney transplant patients suffering from gingival overgrowth, mean score of gingival overgrowth was 1.38 ± 0.60, whereas in control subjects it was 0.0. The patients with gingival overgrowth were characterized by similar distribution of TGFB1 genotypes and allele in comparison to subjects without gingival overgrowth. Among 16 potentially possible haplotypes of TGFB1 gene, only four were observed in the studied sample of kidney transplant patients: G_C_T_G, G_T_C_G, G_C_C_C, and A_C_T_G, with similar frequency in patients with and without gingival overgrowth.

CONCLUSION

No association between the TGFB1 gene polymorphism and gingival overgrowth was revealed in kidney transplant patients administered cyclosporine A.

Proteomic analysis in cyclosporin A-induced overgrowth of human gingival fibroblasts

Cyclosporin A (CsA) has been used as an immunosuppressive drug to prevent organ transplant rejection and to treat autoimmune diseases. CsA has a proliferative effect on human gingival fibroblasts (HGF) in vitro. However, the molecular mechanisms underlying CsA-induced proliferation in HGF remain to be elucidated. This study was aimed to investigate the CsA responsive proteins in HGF using systematic proteomic approach. Cell viability was determined by MTT assay and reactive oxygen species (ROS) was measured by fluorescent spectrometer. Proteins profiled by two-dimensional gel electrophoresis (2-DE) were identified by matrix-assisted laser desorption ionization time-of flight (MALDI-TOF) and electrospray ionization quadrupole time-of-flight mass spectrometry (EIQ-TOF MS). To confirm the expression changes of proteins by proteomics analysis, Western blot was performed using specific antibody. CsA increased the cell viability of HGF in a dose- and time-dependent manner. Significantly, seventeen proteins were overexpressed in the CsA-treated HGF, whereas three proteins were found to be expressed less than the untreated cells. The identified proteins were mainly related with cell proliferation, metabolism, and oxidation. The overexpression of peroxiredoxin 1 (Prx 1) confirmed by Western blotting and reduction of cytosolic reactive oxygen species (ROS) levels in the CsA-treated HGF demonstrated that Prx 1 may play a crucial role in the HGF proliferation induced by CsA. Upregulation of Galectin 3 in CsA-treated HGF indicated that it is related to CsA-induced proliferation. These proteomic analysis data will provide an efficient approach in understanding the mechanisms of HGF proliferation by CsA.

Down-regulation of transforming growth factor beta-2 expression is associated with the reduction of cyclosporin induced gingival overgrowth in rats treated with roxithromycin: an experimental study

Background

Gingival overgrowth (GO) is a common side effect of the chronic use of cyclosporine (CsA), an immunosuppressant widely used to prevent rejection in transplant patients. Recent studies have reported elevated levels of specific cytokines in gingival overgrowth tissue, particularly TGF-beta, suggesting that this growth factor plays a role in the accumulation of extracellular matrix materials. The effectiveness of azithromycin, a macrolide antibiotic, in the regression of this undesirable side effect has also been demonstrated.

Methods

In this study, we created an experimental model for assessing the therapeutic effect of roxithromycin in GO and the expression of transforming growth factor beta (TGF-beta2) through immunohistochemistry. We used four groups of rats totaling 32 individuals. GO was induced during five weeks and drug treatment was given on the 6th week as follows: group 1 received saline; group 2 received CsA and was treated with saline on the 6th week; group 3 received CsA and, on the 6th week, ampicilin; and group 4 received CsA during 5 weeks and, on the 6th week, was treated with roxithromycin.

Results

The results demonstrated that roxithromycin treatment was effective in reducing cyclosporine-induced GO in rats. Both epithelial and connective tissue showed a decrease in thickness and a significant reduction in TGF-beta2 expression, with a lower number of fibroblasts, reduction in fibrotic areas and decrease in inflammatory infiltrate.

Conclusion

The present data suggest that the down-regulation of TGF-beta2 expression may be an important mechanism of action by which roxithromycin inhibits GO.

Comparison of Azithromycin and Oral Hygiene Program in the Treatment of Cyclosporine-Induced Gingival Hyperplasia

BACKGROUND

It has been shown that azithromycin improves cyclosporine-induced gingival hyperplasia (GH), but its efficacy was never compared against an efficient oral hygiene program (OHP). The aim of this study was to analyze the effects of azithromycin plus OHP versus OHP alone in patients with cyclosporine-induced GH.

METHODS

After periodontal evaluation, 20 renal transplant recipients received detailed oral hygiene instructions and a complete OHP, and were randomized to control (OHP) or azithromycin groups (OHP plus azithromycin). Patients were re-evaluated after 15 and 30 days. Both groups were similar in time after transplant, age, gender, cyclosporine dose, and cyclosporine through level and serum creatinine. The control group had fewer patients using calcium cannel blockers (10% vs. 70%, p = 0.02).

RESULTS

All patients improved in pain, halitosis, and gum bleeding after OHP. The control group did not improve plaque index (PI) or GH. In contrast, baseline PI decreased from 1.52 +/- 0.28 to 0.50 +/- 0.16 on day 15 (p < 0.01) and to 0.46 +/- 0.14 on day 30 (p < 0.01) in the azithromycin group, and the GH score decreased from 1.9 +/- 0.27 to 0.90 +/- 0.27 on day 15 (p < 0.05) and to 0.70 +/- 0.21 on day 30 (p < 0.01).

CONCLUSION

Azithromycin associated to efficient OHP induced a striking reduction in cyclosporine-induced GH, while efficient OHP alone improved oral symptoms but did not decrease cyclosporine-induced GH.

Roxithromycin reduces cyclosporine-induced gingival hyperplasia in renal transplant patients

Gingival overgrowth (GO) is a common side effect of chronic cyclosporine use. The average prevalence of GO is about 30%, ranging from 10% to 85% in various series, due to diverse aggravating risk factors: drug interactions with calcium channel blockers, age, cyclosporine dose, bacterial plaque, and genetic predisposition. Recent studies have demonstrated elevated levels of specific cytokines particularly transforming growth factor-beta (TGF-beta) in hyperplastic gingival tissue, suggesting that this growth factor plays a role in the accumulation of the extracellular matrix. Until recently treatment for this complication was only surgical. Nowadays, several studies have been performed to evaluate the effects of antibiotic treatment on the regression of GO. In the present study, we used roxithromycin, a macrolide antibiotic that has inhibitory effect on TGF-beta production by inflammatory cells. The results suggested that roxithromycin may be an important therapeutic tool to reduce cyclosporine-induced GO.

Expression of cell-surface heparan sulfate proteoglycans in human cyclosporin-induced gingival overgrowth

BACKGROUND AND OBJECTIVE

Cyclosporin A-induced gingival overgrowth comprises a variety of signaling pathways (including growth factors and proteoglycans) that are still not completely understood. In the present study, gingival overgrowth was investigated in transplant patients receiving cyclosporin A (cyclosporin A group) and compared with gingival tissues never exposed to the drug (control group) by analyzing the gene expression of the cell-surface heparan sulfate proteoglycans syndecan-2, syndecan-4 and betaglycan.

MATERIAL AND METHODS

mRNA analysis was carried out by reverse transcription-polymerase chain reaction amplification of pooled samples from nine patients of the cyclosporin A group and six control subjects. The groups were compared by the Student's t-test.

RESULTS

The expression of heparan sulfate proteoglycans was increased in the cyclosporin A group (165% for syndecan-2, 308% for syndecan-4, and 42% for betaglycan) compared with the control group.

CONCLUSION

Our findings agree with the current concept of cyclosporin A-induced gingival overgrowth and provide new evidence that its noncollagenous extracellular matrix is overexpressed.

Transforming growth factor betas are upregulated in the rat masseter muscle hypertrophied by clenbuterol, a beta2 adrenergic agonist

1. The regulatory mechanism for the hypertrophy of skeletal muscles induced by clenbuterol is unclear. The purpose of the present study was to determine the extent to which transforming growth factor betas (TGFbetas), fibroblast growth factors (FGFs), hepatocyte growth factor (HGF), and platelet-derived growth factors (PDGFs) are involved in the hypertrophy of rat masseter muscle induced by clenbuterol. 2. We measured the mRNA expression levels for TGFbetas, FGFs, HGF, and PDGFs in rat masseter muscle hypertrophied by oral administration of clenbuterol for 3 weeks and determined correlations between the weight of masseter muscle and mRNA expression levels by regression analysis. We determined immunolocalizations of TGFbetas and their receptors (TGFbetaRs). 3. The mRNA expression levels for TGFbeta1, 2, and 3, and for PDGF-B demonstrated clenbuterol-induced elevations and positive correlations with the weight of masseter muscle. In particular, TGFbeta1, 2, and 3 showed strong positive correlations (correlation coefficients >0.6). The mRNA expression levels for PDGF-A, FGF-1 and 2, and HGF showed no significant differences between the control and clenbuterol groups, and no significant correlations. TGFbeta1, 2, and 3 were principally localized in the connective tissues interspaced among myofibers, and TGFbetaRI and II were localized in the periphery and sarcoplasm of the myofibers. 4. These results suggest that paracrine actions of TGFbeta1, 2, and 3 via TGFbetaRI and II could be involved in the hypertrophy of rat masseter muscle induced by clenbuterol. This is the first study to document the involvement of TGFbetas in the hypertrophy of skeletal muscles induced by clenbuterol.