Cyclosporin A decreases the degradation of type I collagen in rat gingival overgrowth

Refining the Mechanism of Drug-Influenced Gingival Enlargement and Its Management

Drug-influenced gingival enlargement (DIGE) or overgrowth manifests as abnormal enlargement of the gingiva due to an adverse effect of certain drug reactions in patients treated with anticonvulsants, immunosuppressants, or calcium channel blockers (CCBs). As the gingival enlargement became significant, it may interfere with the normal oral hygiene measures, aesthetics, as well as masticatory functions of the patients. The exact mechanism of how this undesirable condition develops is yet unknown, and complicated, with non-inflammatory and inflammatory pathways involved. This review illuminates these putative pathways of DIGE and highlights various treatment approaches based on existing research and current observations.

A case series of medication-related fibrovascular hyperplasia following hematopoietic stem cell transplantation for Fanconi anemia

Systemic medications categorized as diphenylhydantoin, calcineurin inhibitor and calcium channel blocker may have effects on the oral cavity by modifying the inflammatory and immune response and causing undesired tissue proliferative reactions. Calcineurin inhibitors are medications commonly used for long periods in patients undergoing allogeneic hematopoietic stem cell transplant (HSCT) and solid organ transplantation. Medication-related fibrovascular hyperplasia (MRFH) is an extra gingival hyperplastic nodular growth associated with medications use. This study reports five cases of pediatric patients (6 to 12-years-old) diagnosed with Fanconi anemia (FA) after HSCT who presented similar oral mucosal lesions associated with the use of cyclosporine, phenobarbital and amlodipine. After excision of the lesions, histopathological analysis described them as pyogenic granuloma (PG). As the aetiology of the lesions manifested by the patients was associated with the use of medications, the final diagnosis was MRFH. Despite the clinical and histopathological similarity between PG and MRFH, it is fundamental to know the aetiological agent for achieving definitive diagnosis and correct management. Considering the etiologic agent (medication) and histopathological findings, it is suggested that the most appropriate term for this manifestation should be "medication-related fibrovascular hyperplasia". The correct nomenclature related to extra gingival hyperplastic lesions identified in patients on medications with potential to induce hyperplastic reactions should be adopted to facilitate scientific communication and improve the treatment.

Biology of Drug-Induced Gingival Hyperplasia: In Vitro Study of the Effect of Nifedipine on Human Fibroblasts

Background: It has been proven that the antihypertensive agent nifedipine can cause gingival overgrowth as a side effect. The aim of this study was to analyze the effects of pharmacological treatment with nifedipine on human gingival fibroblasts activity, investigating the possible pathogenetic mechanisms that lead to the onset of gingival enlargement. Methods: The expression profile of 57 genes belonging to the “Extracellular Matrix and Adhesion Molecules” pathway, fibroblasts’ viability at different drug concentrations, and E-cadherin levels in treated fibroblasts were assessed using real-time Polymerase Chain Reaction, PrestoBlue™ cell viability test, and an enzyme-linked immunoassay (ELISA), respectively. Results: Metalloproteinase 24 and 8 (MMP24, MMP8) showed significant upregulation in treated cells with respect to the control group, and cell adhesion gene CDH1 (E-cadherin) levels were recorded as increased in treated fibroblasts using both real-time PCR and ELISA. Downregulation was observed for transmembrane receptors ITGA6 and ITGB4, the basement membrane constituent LAMA1 and LAMB1, and the extracellular matrix protease MMP11, MMP16, and MMP26. Conclusions: The obtained data suggested that the pathogenesis of nifedipine-induced gingival overgrowth is characterized by an excessive accumulation of collagen due to the inhibition of collagen intracellular and extracellular degradation pathways.

Crown Lengthening surgery: An overview

The term 'crown lengthening surgery' refers to a variety of techniques which aim to expose a greater amount of tooth structure around a tooth or group of teeth. The decision to treat and which technique to use will depend upon: the underlying aetiology; a thorough history and examination; results of any supporting investigations and a clear understanding of the intended outcome of treatment. This paper aims to provide an overview of crown lengthening surgery and is illustrated with clinical cases.

Role of Cyclosporine in Gingival Hyperplasia: An In Vitro Study on Gingival Fibroblasts

BACKGROUND

Gingival hyperplasia could occur after the administration of cyclosporine A. Up to 90% of the patients submitted to immunosuppressant drugs have been reported to suffer from this side effect. The role of fibroblasts in gingival hyperplasia has been widely discussed by literature, showing contrasting results. In order to demonstrate the effect of cyclosporine A on the extracellular matrix component of fibroblasts, we investigated the gene expression profile of human fibroblasts after cyclosporine A administration.

MATERIALS AND METHODS

Primary gingival fibroblasts were stimulated with 1000 ng/mL cyclosporine A solution for 16 h. Gene expression levels of 57 genes belonging to the "Extracellular Matrix and Adhesion Molecules" pathway were analyzed using real-time PCR in treated cells, compared to untreated cells used as control.

RESULTS

Expression levels of different genes were significantly de-regulated. The gene CDH1, which codes for the cell adhesion protein E-cadherin, showed up-regulation. Almost all the extracellular matrix metalloproteases showed down-regulation (MMP8, MMP11, MMP15, MMP16, MMP24, MMP26). The administration of cyclosporine A was followed by down-regulation of other genes: COL7A1, the transmembrane receptors ITGB2 and ITGB4, and the basement membrane constituents LAMA2 and LAMB1.

CONCLUSION

Data collected demonstrate that cyclosporine inhibits the secretion of matrix proteases, contributing to the accumulation of extracellular matrix components in the gingival connective tissue, causing gingival overgrowth. Patients affected by gingival overgrowth caused by cyclosporine A need to be further investigated in order to determine the role of this drug on fibroblasts.

Molecular Aspects of Drug-Induced Gingival Overgrowth: An In Vitro Study on Amlodipine and Gingival Fibroblasts

Gingival overgrowth is a serious side effect that accompanies the use of amlodipine. Several conflicting theories have been proposed to explain the fibroblast’s function in gingival overgrowth. To determine whether amlodipine alters the fibrotic response, we investigated its effects on treated gingival fibroblast gene expression as compared with untreated cells. Materials and Methods: Fibroblasts from ATCC^® Cell Lines were incubated with amlodipine. The gene expression levels of 12 genes belonging to the “Extracellular Matrix and Adhesion Molecules” pathway was investigated in treated fibroblasts cell culture, as compared with untreated cells, by real time PCR. Results: Most of the significant genes were up-regulated. (CTNND2, COL4A1, ITGA2, ITGA7, MMP10, MMP11, MMP12, MMP26) except for COL7A1, LAMB1, MMP8, and MMP16, which were down-regulated. Conclusion: These results seem to demonstrate that amlodipine has an effect on the extracellular matrix of gingival fibroblast. In the future, it would be interesting to understand the possible effect of the drug on fibroblasts of patients with amlodipine-induced gingival hyperplasia.

Periodontal complications of prescription and recreational drugs

Drug use for both therapeutic and recreational purposes is very widespread in most societies. The range of drugs used, the variations in response to these drugs and other health and behavioral confounders mean that drug use may be an important contributor to individualized periodontal diagnoses. In this narrative review, we review the main reported effects of drugs on the periodontal tissues and periodontal disease processes. Although some of the more common adverse drug reactions on periodontal tissues are well described, in many other cases the evidence for these drug effects is quite limited and based on small case series or isolated reports. Prescription drugs are responsible for a range of effects, including drug-induced gingival overgrowth and increased gingival bleeding, and influence periodontal inflammation and periodontal breakdown. The effects of recreational drugs on the periodontal tissues is less well researched, perhaps for the obvious reason that assembling large cohorts of recreational drug users presents particular challenges. Use of nearly all of these substances is associated with poorer periodontal and dental health, although there is almost certainly a large degree of behavioral confounding in these findings. Overall, further studies of adverse drug reactions on the periodontal tissues are required as this continues to be an important and increasing factor in periodontal health determination.

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.

Connective Tissue Metabolism and Gingival Overgrowth

Gingival overgrowth occurs mainly as a result of certain anti-seizure, immunosuppressive, or antihypertensive drug therapies. Excess gingival tissues impede oral function and are disfiguring. Effective oral hygiene is compromised in the presence of gingival overgrowth, and it is now recognized that this may have negative implications for the systemic health of affected patients. Recent studies indicate that cytokine balances are abnormal in drug-induced forms of gingival overgrowth. Data supporting molecular and cellular characteristics that distinguish different forms of gingival overgrowth are summarized, and aspects of gingival fibroblast extracellular matrix metabolism that are unique to gingival tissues and cells are reviewed. Abnormal cytokine balances derived principally from lymphocytes and macrophages, and unique aspects of gingival extracellular matrix metabolism, are elements of a working model presented to facilitate our gaining a better understanding of mechanisms and of the tissue specificity of gingival overgrowth.

Oral Pyogenic Granuloma After Bone Marrow Transplant in the Pediatric/Adolescent Population: Report of 5 Cases

Pyogenic granuloma (PG) is a benign, neoplastic, soft tissue growth of granulation and fibrous tissue that may rarely occur in the mouth of patients after hematopoietic cell transplant (HCT). This case series describes 5 pediatric/adolescent patients who developed oral PG after HCT for acute lymphoblastic leukemia, Fanconi anemia, nodular sclerosis Hodgkin's lymphoma, or junctional epidermolysis bullosa. The underlying mechanism for the appearance of oral PG after HCT is unknown, but it is suggested that calcineurin inhibitors used for graft versus host disease (GVHD) may play a role, as all patients were on cyclosporine A or tacrolimus at the time of development of oral PG. Three of the patients were being treated for chronic GVHD, and 1 other treated for acute GVHD. Overall, this report illustrates that PG should be considered in the differential diagnoses when encountering oral lesions in pediatric/adolescent patients after undergoing HCT, especially in the context of chronic GVHD and calcineurin inhibitors use.

The Relationship between Proliferating Cell Nuclear Antigen Expression and Histomorphometrical Alterations in Cyclosporin A-Induced Gingival Overgrowth in Rats

The aim of this study was to investigate the relationship between Proliferating Cell Nuclear Antigen (PCNA) expression and histomorphometrical alterations in cyclosporin A (CsA)-induced gingival overgrowth with or without microbial dental plaque accumulation. Forty male Wistar rats were equally divided into 4 groups; Group I (control); Group II (CsA); Group III (ligature); Group IV (ligature and CsA). After 8 weeks of experimental period, rats were subsequently decapitated and mandibular molars were dissected. Gingival overgrowth was determined by measuring depth of the gingival sulcus, then the mandible were decalcified and serial sections were obtained for histomorphometric and immunohistochemical analysis. Histomorphometric analysis included the measurement of epithelial thickness; immunohistochemical analysis included the assessment of PCNA expression in the oral and sulcular epithelium of buccal and lingual gingiva. Epithelial thickness and PCNA expression were significantly increased in buccal oral epithelium of Group II ( p < 0.05) and in all regions in Group IV ( p < 0.05) compared to control group. Also gingival overgrowth was more prominent in Group IV in comparison to Group II. These results indicate that CsA-induced gingival alterations are closely accociated with increased epithelial proliferative activity, and dental plaque accumulation seems not to be an essential but to be an aggrevating factor for the progression of the lesion.

In vivo association of immunophenotyped macrophages expressing CD163 with PDGF-B in gingival overgrowth-induced by three different categories of medications

AIMS

This study was carried out to identify and outline the degree of relationship between immunophenotyped macrophages expressing CD163 and PDGF-B in cyclosporine-A, phenytoin, and nifedipine-induced gingival overgrowth.

METHODS

Eighty adult male albino rats were selected and divided into four equal groups. Group I received no treatment. Rats of groups II, III, and IV were administered cyclosporine-A, phenytoin, and nifedipine, respectively. Routine tissue processing was carried out for staining with CD163 and PDGF-B. The results of this study were analyzed statistically.

RESULTS

Group I exhibited score 0 gingival overgrowth while group II yielded score 3 with blunt and bulbous gingival crests. Rats of group III showed score 2 with knife edge and group IV revealed less pronounced gingival overgrowth and mostly the gingival crest was knife edge. Group II had the highest mean value for CD163 while group I showed the lowest value. In addition, group II had the highest mean value for PDGF-B while group I showed the lowest value. Statistically, there was an overall significant difference between the studied groups as well as between each two groups.

CONCLUSION

Strong association exists between immunophenotyped macrophages expressing CD163 and PDGF-B in GO induced by these medications. In addition, CD163 and PDGF-B upregulated in cyclosporine-A-induced GO compared to phenytoin and nifedipine medications.

Effect of azithromycin on gingival overgrowth induced by cyclosporine A + nifedipine combination therapy: A morphometric analysis in rats

Background:

Drug-induced gingival overgrowth (DIGO) is a well-known adverse effect of cyclosporine A (CsA) and nifedipine (Nf) therapy. The aim of the present morphometric study was to evaluate the effect of azithromycin (Azi) on the combined GO in rats induced by CsA + Nf combination.

Materials and Methods:

Thirty Sprague-Dawley male rats were randomly divided equally into three groups. Group 1 (control) received olive oil only; Group 2 received a combination of CsA and Nf in olive oil throughout the study period; Group 3 received CsA + Nf combination therapy, and Azi was added for 1 week in the 5^th week. All the drugs were delivered by oral route. Impressions of the mandibular central incisal regions were taken, and study models were prepared at baseline and biweekly up to the 8 weeks. Statistical analysis was done by one-way analysis of variance and intergroup comparisons were made using Tukey's post hoc analysis.

Results:

Significant GO was evident in Group 2 and Group 3 rats when compared to Group 1. However, in Group 3 (Azi), GO was observed up to the 4^th week, but a significant decrease in GO was noticed during 6–8^th week after the administration of Azi in 5^th week.

Conclusion:

Azi is an effective drug in the remission of DIGO induced by combined therapy of CsA + Nf and thereby can be considered as a useful therapeutic regimen in minimizing the DIGO in transplant patients.

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.

Altered oxidative status and integrin expression in cyclosporine A-treated oral epithelial cells

BACKGROUND AND OBJECTIVE

Cyclosporine A (CsA) is an immunosuppressive agent administered to transplant patients. A well-known reported oral side effect of CsA consumption is gingival overgrowth (GO). Changes in the expression of integrins occurring in the gingiva following CsA treatment have been reported but these reports are mainly concerned with the connective tissue of the gingiva. In this study we targeted the alterations in the oral epithelium using KB cells, an oral epithelial cell line.

METHODS

Cultured oral epithelial cells were treated with increasing concentrations of CsA (0.1, 1 and 10 µg/mL) and the molecular changes involving antioxidant enzymes [glutathione peroxidase (GPx) and glutathione reductase (GR)] and the level of reactive oxygen species (ROS) were measured. Quantitative real-time PCR was used to assess the expression of selected integrins (α2, α5 and β1).

RESULTS

At CsA concentration above 0.1 µg/mL GPx demonstrated an increase in activity while GR activity and the level of reduced glutathione were diminished (p < 0.05). α5 and β1 integrin were downregulated at all treatment concentrations of CsA while α2 integrin presented this effect at concentrations above 1 µg/mL (p < 0.05).

CONCLUSION

The results suggest a possible role for oxidative stress and the altered expression of integrins in the pathology of CsA-induced gingival overgrowth.

Adverse drug events in the oral cavity

Adverse reactions to medications are common and may have a variety of clinical presentations in the oral cavity. Targeted therapies and the new biologic agents have revolutionized the treatment of cancers, autoimmune diseases, and inflammatory and rheumatologic diseases but have also been associated with adverse events in the oral cavity. Some examples include osteonecrosis, seen with not only bisphosphonates but also antiangiogenic agents, and the distinctive ulcers caused by mammalian target of rapamycin inhibitors. As newer therapeutic agents are approved, it is likely that more adverse drug events will be encountered. This review describes the most common clinical presentations of oral mucosal reactions to medications, namely, xerostomia, lichenoid reactions, ulcers, bullous disorders, pigmentation, fibrovascular hyperplasia, white lesions, dysesthesia, osteonecrosis, infection, angioedema, and malignancy. Oral health care providers should be familiar with such events, as they will encounter them in their practice.

Alpha 2 integrin gene (ITGA2) polymorphism in renal transplant recipients with and without drug induced gingival overgrowth

BACKGROUND

Variances in fibroblasts' α2β1 integrin intensity may lead to altered adhesion to type I collagen and consequently to suppression of phagocytosis which may be one of the mechanisms for drug induced gingival overgrowth. The present study aimed to evaluate the genotype and allele frequencies of α2 integrin +807 gene in renal transplant patients with and without gingival overgrowth.

MATERIAL AND METHODS

Seventy renal transplant patients with cyclosporine A (CsA)-induced gingival overgrowth (CsA GO+) were enrolled. Renal transplant patients without GO medicated with CsA (CsA GO-; n=79) and tacrolimus (Tac; n=52) served as controls. DNA was obtained from peripheral blood and ITGA2 +807C/T polymorphism was genotyped by polymerase chain reaction and restriction fragment length polymorphism method. Clinical parameters including probing depth and plaque, papilla bleeding and hyperplasia indexes were recorded. Chi-square, Kruskal-Wallis and Mann-Whitney tests were used in statistical analysis.

RESULTS

Clinical parameters of CsA GO+ group were significantly higher than those of the CsA GO- and Tac groups (p<0.05). ITGA2 807C/T genotype and allele frequencies of study groups were similar (p>0.05).

CONCLUSION

Within the limits of the present study it can be concluded that ITGA2 +807 gene polymorphism is not associated with susceptibility to CsA-induced GO.

In Vitro Analysis of CsA-Induced Hepatotoxicity in HepG2 Cell Line: Oxidative Stress and α2 and β1 Integrin Subunits Expression

BACKGROUND

Cyclosporine A (CsA)-induced hepatotoxicity could be due to a reduction in α2β1 integrin expression that may either be from the direct effect of CsA itself or from reactive oxygen species (ROS) overproduction.

OBJECTIVES

In this study we aimed to identify the cellular mechanisms underlying CsA-induced hepatic injury by investigating the activation patterns of the antioxidant enzymes, using HepG2 as an in vitro model.

MATERIALS AND METHODS

HepG2 cells were cultured with different concentrations of CsA (0, 0.1, 1, 10 μg/ml) for 72 h. Effect of CsA on, 1) cellular integrity, 2) glutathione reductase (GR) and glutathione peroxidase (GPx) activity, 3) cellular levels of glutathione (GSH), 4) intracellular ROS, 5) ALT and AST activities, 6) urea production and 7) α2β1 integrin expression were assayed.

RESULTS

CsA treatment demonstrated a dose dependent increase in intracellular levels of ROS, GPx activity and decrease in GSH levels (P<0.05). GR activity was mildly attenuated in 1 and 10 µg/ml concentrations of CsA. Alanine aminotranferase (ALT) and aspartate aminotransferase (AST) levels increased in CsA treated cells, while urea synthesis was significantly decreased following treatment with higher concentrations of CsA (P<0.05). Significant down-regulation of β1integrin expression was observed in 1 and 10 µg/ml CsA treated cells while α2 integrin mRNA was significantly down-regulated in all CsA treated cells.

CONCLUSIONS

The observed reduction of α2β1 integrin expression following CsA treatment could be proposed as a possible pathway of CsA-induced hepatotoxicity. Further studies are required to elucidate whether this attenuated expression is due to the direct effect of CsA or caused by overproduction of ROS.

Cyclosporin A reduces matrix metalloproteinases and collagen expression in dermal fibroblasts from regenerative FOXN1 deficient (nude) mice

Background

Cyclosporin A (CsA), an immunosuppressive agent modifies the wound healing process through an influence on extracellular matrix metabolism. We have compared the effects of CsA on dermal fibroblasts from nude (FOXN1 deficient) mice, a genetic model of skin scarless healing, and from control (C57BL/6 J (B6) mice to evaluate metabolic pathways that appear to have important roles in the process of scarless healing/regeneration.

Results

High levels of matrix metalloproteinases (MMPs) and collagen III expression in dermal fibroblasts from nude (regenerative) mice were down-regulated by CsA treatment to the levels observed in dermal fibroblasts from B6 (non-regenerative) mice. In contrast, dermal fibroblasts from control mice respond to CsA treatment with a minor reduction of Mmps mRNA and 2.5-fold increase expression of collagen I mRNA. An in vitro migratory assay revealed that CsA treatment profoundly delayed the migratory behavior of dermal fibroblasts from both nude and control mice.

Conclusion

The data suggest that by alternation of the accumulation of extracellular matrix components CsA treatment stimulates the transition from a scarless to a scar healing.

Advanced glycation end-products enhance calcification in cultured rat dental pulp cells

INTRODUCTION

Amorphous calcification frequently appears in dental pulp tissues of diabetic patients; however, its pathologic process has not been fully elucidated. We previously found that pulp stones and thickened predentin occurred more frequently in diabetic rats. Recent findings demonstrated that accumulation of advanced glycation end-products (AGE) might be involved in vascular calcification complicated with diabetes. The aim of this study was to determine the effect of AGE on calcified nodule formation by rat dental pulp cells in culture.

METHODS

Rat dental pulp cells and gingival fibroblasts were independently cultured with 50 and 100 μg/mL AGE. Alkaline phosphatase activity and calcified nodule formation were measured. Expressions of receptor for AGE, osteopontin (OPN), and osteocalcin (OCN) mRNA were determined by quantitative real-time polymerase chain reaction. Protein levels of OPN and OCN secreted in culture medium were quantified by enzyme-linked immunosorbent assay.

RESULTS

AGE (50 and 100 μg/mL) markedly increased both alkaline phosphatase activity and calcified nodule formation in dental pulp cells (P < .01), whereas it did not affect those in gingival fibroblasts. Real-time polymerase chain reaction analysis revealed that AGE increased mRNA expressions of receptor for AGE, OPN, and OCN in dental pulp cells (P < .05). Enzyme-linked immunosorbent assay analysis revealed that the protein levels of OPN and OCN produced by dental pulp cells were higher in AGE-treated than in untreated cells (P < .05).

CONCLUSIONS

AGE enhanced the calcification potentials of rat dental pulp cells, suggesting that it may stimulate pathologic calcification of diabetic dental pulp tissues.

Suppression of LPS-induced matrix-metalloproteinase responses in macrophages exposed to phenytoin and its metabolite, 5-(p-hydroxyphenyl-), 5-phenylhydantoin

BACKGROUND

Phenytoin (PHT) has been reported to induce gingival (gum) overgrowth (GO) in approximately 50% of patients taking this medication. While most studies have focused on the effects of PHT on the fibroblast in the pathophysiology underlying GO, few studies have investigated the potential regulatory role of macrophages in extracellular matrix (ECM) turnover and secretion of proinflammatory mediators. The aim of this study was to evaluate the effects of PHT and its metabolite, 5-(p-hydroxyphenyl-), 5-phenylhydantoin (HPPH) on LPS-elicited MMP, TIMP, TNF-α and IL-6 levels in macrophages.

METHODS

Human primary monocyte-derived macrophages (n = 6 independent donors) were pretreated with 15-50 μg/mL PHT-Na+ or 15-50 μg/mL HPPH for 1 hour. Cells were then challenged with 100 ng/ml purified LPS from the periodontal pathogen, Aggregatibacter actinomycetemcomitans. Supernatants were collected after 24 hours and levels of MMP-1, MMP-2, MMP-3, MMP-9, MMP-12, TIMP-1, TIMP-2, TIMP-3, TIMP-4, TNF-α and IL-6 determined by multiplex analysis or enzyme-linked immunoadsorbent assay.

RESULTS

A dose-dependent inhibition of MMP-1, MMP-3, MMP-9, TIMP-1 but not MMP-2 was noted in culture supernatants pretreated with PHT or HPPH prior to LPS challenge. MMP-12, TIMP-2, TIMP-3 and TIMP-2 were not detected in culture supernatants. High concentrations of PHT but not HPPH, blunted LPS-induced TNF-α production although neither significantly affected IL-6 levels.

CONCLUSION

The ability of macrophages to mediate turnover of ECM via the production of metalloproteinases is compromised not only by PHT, but its metabolite, HPPH in a dose-dependent fashion. Further, the preferential dysregulation of macrophage-derived TNF-α but not IL-6 in response to bacterial challenge may provide an inflammatory environment facilitating collagen accumulation without the counteracting production of MMPs.

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.

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.

Mechanism of Azithromycin Treatment on Gingival Overgrowth

Azithromycin is effective for the remission of cyclosporine A-induced gingival overgrowth (CIGO) in persons who have undergone renal transplant. To explain its mechanism in alleviating the clinical symptoms of these indivduals, we examined the effect of azithromycin on cell proliferation and collagen turnover modified by cyclosporin A in human gingival fibroblasts from healthy persons and from persons who had undergone renal transplant. Cyclosporin A-induced proliferation of renal transplant fibroblasts and normal fibroblasts was inhibited by azithromycin. Azithromycin elevated the reduced metalloproteinase (MMP)-1 and MMP-2 activities in cyclosporine A-treated renal transplant fibroblasts and normal fibroblasts. In cyclosporine A-treated renal transplant fibroblasts, azithromycin blocked the accumulation of total collagen in culture media and the increase in type I collagen mRNA level, but recovered the reduced MMP-2 mRNA level to the control. These results suggest that azithromycin may improve CIGO by blocking cyclosporine A-induced cell proliferation and collagen synthesis, and by activating MMP-2 in gingival fibroblasts of persons with cyclosporine A-induced gingival overgrowth.

Gingival crevicular fluid and serum matrix metalloproteinase-8 and tissue inhibitor of matrix metalloproteinase-1 levels in renal transplant patients undergoing different immunosuppressive therapy

AIM

We investigated gingival crevicular fluid (GCF) and serum matrix metalloproteinase-8 (MMP-8) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) levels from renal transplant patients receiving cyclosporine-A (CsA) and having gingival overgrowth (GO), from patients receiving CsA therapy and having no GO and patients receiving tacrolimus therapy.

MATERIAL AND METHODS

GCF samples were collected from sites with GO (GO+) and without GO (GO-) in CsA patients having GO; and GO- sites in CsA patients having no GO; sites from tacrolimus, gingivitis and healthy subjects. GCF and serum MMP-8 and TIMP-1 levels were determined by a time-resolved immunofluorometric assay (IFMA) and enzyme-linked immunosorbent assay.

RESULTS

GO+ sites in CsA patients having GO had elevated GCF MMP-8 levels compared with those of CsA patients having no GO, tacrolimus and healthy subjects (p<0.005), but these levels were similar to those of gingivitis. The GCF MMP-8 level was higher in GO+ compared with GO- sites in CsA patients having GO (p<0.05). GCF TIMP-1 levels were similar between groups. Tacrolimus patients had lower GCF MMP-8 levels than gingivitis (p<0.005), but levels similar to the healthy group.

CONCLUSION

These results show that CsA and tacrolimus therapy has no significant effect on GCF MMP-8 levels, and gingival inflammation seems to be the main reason for their elevations.

Calcineurin inhibitor-associated oral inflammatory polyps after transplantation

Calcineurin inhibitors (cyclosporine and tacrolimus) have been used as the mainstay immunosuppressive therapy for solid organ and hematopoietic cell transplantations (HCT) to prevent allograft rejection and for prophylaxis and treatment of the chronic graft-versus-host disease. Adverse effects of these drugs include nephrotoxicity, hepatotoxicity, neurotoxicity, hypertension and gingival hyperplasia. Association of oral non-gingival soft tissue hyperplasia with calcineurin inhibitor therapy has only recently been recognized and is thought to occur infrequently. We present four cases of oral non-gingival inflammatory fibro-vascular hyperplasias attributed to the use of calcineurin inhibitors following solid organ transplantation and HCT. These lesions interfere with function and must be differentiated from other oral lesions, and therefore should be surgically excised.

Alendronate therapy in cyclosporine-induced alveolar bone loss in rats

BACKGROUND AND OBJECTIVE

Cyclosporine A is an immunosuppressive drug that is widely used in organ transplant patients as well as to treat a number of autoimmune conditions. Bone loss is reported as a significant side-effect of cyclosporine A use because this can result in serious morbidity of the patients. As we have shown that cyclosporine A-associated bone loss can also affect the alveolar bone, the purpose of this study was to evaluate the effect of the concomitant administration of alendronate on alveolar bone loss in a rat model.

MATERIAL AND METHODS

Forty Wistar rats (10 per group) were given cyclosporine A (10 mg/kg, daily), alendronate (0.3 mg/kg, weekly), or both cyclosporine A and alendronate, for 60 d. The control group received daily injections of sterile saline. The expression of proteins associated with bone turnover, including osteocalcin, alkaline phosphatase and tartrate-resistant acid phosphatase (TRAP), and also the calcium levels, were evaluated in the serum. Analysis of the bone volume, alveolar bone surface, the number of osteoblasts per bone surface and the number of osteoclasts per bone surface around the lower first molars was also performed.

RESULTS

The results indicate that cyclosporine A treatment was associated with bone resorption, represented by a decrease in the bone volume, alveolar bone surface and the number of osteoblasts per bone surface and by an increase in the number of osteoclasts per bone surface and TRAP-5b. These effects were effectively counteracted by concomitant alendronate administration.

CONCLUSION

It is concluded that concomitant administration of alendronate can prevent cyclosporine A-associated alveolar bone loss.

Conversion of immunosuppressive monotherapy from cyclosporin a to tacrolimus reverses bone loss in rats

Tacrolimus is used for transplant patients with refractory graft rejection and those with intolerance to cyclosporin (CsA), without the disfiguring adverse effects frequently attributed to CsA therapy. Since we have shown that CsA-associated bone loss can also affect alveolar bone, the purpose of this study was to evaluate the effects of conversion of monotherapy from CsA to tacrolimus on alveolar bone loss in rats. Groups of rats were treated with either CsA (10 mg/kg/day, s.c.), tacrolimus (1 mg/kg/day, s.c.), or drug vehicle for 60 and 120 days, and an additional group received CsA for 60 days followed by conversion to tacrolimus for a further 60-day period. Bone-specific alkaline phosphatase (BALP), tartrate-resistent acid phosphatase (TRAP-5b), calcium (Ca(2+)), interleukin (IL)-1beta, IL-6, and tumor necrosis factor alpha (TNF-alpha) concentrations were evaluated in the serum. Analyses of bone volume, bone surface, number of osteblasts, and osteoclasts were performed. Treatment with CsA for either 60 or 120 days was associated with bone resorption, represented by lower bone volume and increased number of osteoclasts; serum BALP, TRAP-5b, IL-1beta, IL-6, and TNF-alpha were also higher in these animals. After conversion from CsA to tacrolimus, all the altered serum markers returned to control values in addition to a significant increase of bone volume and a lower number of osteoclasts. This study shows that conversion from CsA to tacrolimus therapy leads to a reversal of the CsA-induced bone loss, which can probably be mediated by downregulation of IL-1beta, IL-6, and TNF-alpha production.

Cyclosporin inhibition of collagen remodeling is mediated by gelsolin

Cyclosporin A (CsA) inhibits collagen remodeling by interfering with the collagen-binding step of phagocytosis. In rapidly remodeling connective tissues such as human periodontium this interference manifests as marked tissue overgrowth and loss of function. Previous data have shown that CsA inhibits integrin-induced release of Ca(2+) from internal stores, which is required for the binding step of collagen phagocytosis. Because gelsolin is a Ca(2+)-dependent actin-severing protein that mediates collagen phagocytosis, we determined whether gelsolin is a CsA target. Compared with vehicle controls, CsA treatment of wild-type mice increased collagen accumulation by 60% in periodontal tissues; equivalent increases were seen in vehicle-treated gelsolin-null mice. Collagen degradation by phagocytosis in cultured gelsolin wild-type fibroblasts was blocked by CsA, comparable to levels of vehicle-treated gelsolin-null fibroblasts. In wild-type cells treated with CsA, collagen binding was similar to that of gelsolin-null fibroblasts transfected with a gelsolin-severing mutant and treated with vehicle. CsA blocked collagen-induced Ca(2+) fluxes subjacent to bound collagen beads, gelsolin recruitment, and actin assembly at bead sites. CsA reduced gelsolin-dependent severing of actin in wild-type cells to levels similar to those in gelsolin-null fibroblasts. We conclude that CsA-induced accumulation of collagen in the extracellular matrix involves disruption of the actin-severing properties of gelsolin, thereby inhibiting the binding step of collagen phagocytosis.

Elevated levels of gene expression for collagen and decorin in human gingival overgrowth

OBJECTIVES

It has been demonstrated that extracellular matrix molecules are involved in cyclosporine-induced gingival overgrowth (GO). However, for many of these molecules, it remains unclear whether their abundance is modulated on the protein and gene expression level.

MATERIAL AND METHODS

To contribute to this clarification, we have analysed the protein and mRNA expression of type-I collagen (COL1) and decorin (DC) in native specimens obtained from five patients with GO, and matched normal tissue using indirect immunofluorescence (IIM), in situ hybridization (ISH) and quantitative polymerase chain reaction (PCR).

RESULTS

IIF revealed a largely co-localized although remarkably increased abundance for COL1 and DC in GO. This increase coincided with an up-regulated gene expression observed for both molecules, as detected by ISH and quantitative PCR.

CONCLUSIONS

Analysis of our data clearly demonstrates elevated levels for COL1 and DC and shows for the first time in native human tissue that involvement of these genes in GO is not confined to the protein level but also includes the transcriptional level.

Elevated gene expression of MMP-1, MMP-10, and TIMP-1 reveal changes of molecules involved in turn-over of extracellular matrix in cyclosporine-induced gingival overgrowth

In humans, pathogenesis in cyclosporine A (CsA)-induced gingival overgrowth (GO) includes the accumulation of extracellular matrix (ECM) constituents, viz., collagen type-1 and type-3 and proteoglycans, in subgingival connective tissue. However, whether this increase is associated with alterations of molecules pivotal for the turn-over of collagens and proteoglycans remains unclear. The present study explores the status of matrix metalloproteinase MMP-1 and MMP-10, which are important for fibrillar collagen and proteoglycan turn-over, and their tissue inhibitor TIMP-1, on their gene expression and protein levels in frozen sections derived from GO and matched normal tissue. In situ hybridization (ISH) revealed elevated levels of MMP-1 gene expression in the connective tissue of GO compared with normal tissue. This elevation also applied to MMP-10 and TIMP-1, the latter exhibiting the strongest gene transcription in the deep connective tissue. These differences detected by ISH were corroborated by quantitative reverse transcription/polymerase chain reaction; relative gene expression analysis indicated a 1.9-fold increase for MMP-1, a 2.3-fold increase for MMP-10, and a 4.8-fold increase for TIMP-1. Detection of the protein by indirect immunofluorescence showed that normal gingival tissue was devoid of all three proteins, although they were detectable in GO tissue, with emphasis on TIMP-1. Analysis of our data indicates elevated levels of MMP-1 and-10, and particularly TIMP-1. With respect to TIMP-1, this elevation may in turn lead to alterations in ECM turn-over by abrogating MMP-1 and MMP-10, thereby contributing to ECM accumulation associated with GO.

Oral health in renal transplant recipients administered cyclosporin A or tacrolimus

OBJECTIVE

The aim of this study was to determine the oral status of renal transplant recipients receiving cyclosporin A (CsA) or tacrolimus (FK-506) as immunosuppressant.

SUBJECTS AND METHODS

A total of 88 renal transplant recipients receiving CsA (63 men and 25 women, mean age 51.4 years) and 67 receiving FK-506 (57 men and 10 women, mean age 33.5 years) were included in the study. Donor type, histocompatibility, cold ischemia time and prior delayed graft function were similar between the two groups. Demographics and pharmacological data were recorded for all subjects.

RESULTS

The results demonstrated that CsA caused a greater number of oral diseases. A greater number of gingival overgrowth was present in patients treated with CsA. However, the combined use with calcium channel blockers increased the gingival overgrowth number. The occurrence of candida in saliva was observed in 80 renal recipients treated with CsA and 20 treated with FK-506. The presence of squamous oral carcinoma (n = 3) and herpes simplex (n = 10) was observed in patients treated with CsA. These alterations were not observed in renal recipients treated with FK-506.

CONCLUSIONS

Renal recipients constitute a high-risk group for oral diseases, as they are immunocompromised. However, the FK-506 regime appears to ameliorate this effect, compared with CsA. Adequate pre- and post-transplant oral health care is recommended for these subjects, irrespective of the time interval for which the drug is administered.

Drug-induced gingival overgrowth--a review

Drug-induced gingival overgrowth is a side effect associated with 3 types of drugs: anticonvulsants (phenytoin), immunosuppressive agents (cyclosporine A), and various calcium channel blockers for cardiovascular diseases. Gingival overgrowth is characterized by the accumulation of extracellular matrix in gingival connective tissues, particularly collagenous components with various degrees of inflammation. Although the mechanisms of these disorders have not been elucidated, recent studies suggest that these disorders seem to be induced by the disruption of homeostasis of collagen synthesis and degradation in gingival connective tissue, predominantly through the inhibition of collagen phagocytosis of gingival fibroblasts. The integrins are a large family of heterodimeric transmembrane receptors for extracellular matrix molecules. alpha2beta1 integrin serves as a specific receptor for type I collagen on fibroblasts, and alpha2 integrin has been shown to play a crucial role in collagen phagocytosis. Actin filaments, which are assembled from monomers and oligomers, are involved in collagen internalization after binding to integrins. Furthermore, the implication of intracellular calcium in the regulation of integrin-mediated binding activity and gelsolin activity, known as a calcium-dependent actin-severing protein, is also described. In this review, we focus on collagen metabolism in drug-induced gingival overgrowth, focusing on the regulation of collagen phagocytosis in fibroblasts.

Alpha 2 integrin +807 polymorphism in drug-induced gingival overgrowth

Alpha2 integrin on fibroblasts is reported to play an important role in the induction of drug-induced gingival overgrowth, which is characterized by excessive accumulation of type I collagen in gingival connective tissue. Silent polymorphism 807 T/C within the alpha2 integrin gene is associated with high/low alpha2 integrin expression. The aim of this study was to test the hypothesis that expression of alpha2 integrin 807 T/C polymorphism correlates with drug-induced gingival overgrowth. A case-control study comparing 136 subjects taking calcium channel blockers (72 with vs. 64 without drug-induced gingival overgrowth) demonstrated that the frequency of the +807 C allele was significantly higher in the case group than in the controls (odds ratio, 3.61; 95% confidence interval, 2.14 - 6.10; P < 0.05). The present findings suggest that the alpha2 +807 C allele is one of the genetic risk factors for drug-induced gingival overgrowth.

High-turnover osteoporosis is induced by cyclosporin A in rats

Cyclosporin A (CsA) is used widely as an immunosuppressive agent, but it induces osteoporosis as a prominent side effect. To elucidate the mechanisms involved in CsA-induced osteoporosis, the effects of CsA on bone metabolism were investigated in a rat experimental model. Fifteen-day-old rats were fed a powdered diet containing or lacking CsA for 8-30 days. Analysis was performed by micro-computed tomography (muCT) and light microscopy to examine histomorphometric changes in rat tibiae on days 8, 16, and 30. Plasma parathyroid hormone (PTH) and osteocalcin (OCN) levels were determined by enzyme-linked immunosorbent assay (ELISA) on days 8, 16, and 30. The expression of OCN, osteopontin (OPN), and cathepsin K mRNAs in tibial bone marrow was examined by Northern blot analysis on days 8 and 16. Although no significant differences were observed in tibial length during the experimental periods, or in histomorphometric parameters on day 8, an apparent decrease in bone volume was observed in the CsA-treated group after day 16. Histologic analysis showed that the number of osteoblasts and osteoclasts on the surface of trabecular bone in the CsA-treated group had increased significantly on day 16. Plasma PTH and OCN levels in CsA-treated rats were significantly higher than those in control animals on day 8. Northern blot analysis revealed that the CsA-treated group showed an increase in the expression of OCN, OPN, and cathepsin K mRNAs on day 8 compared with the controls. These findings suggest that bone resorption in CsA-treated rats is induced by high-turnover osteoporosis and that bone remodeling activity may be activated by PTH.

Increased Expression of Vascular Endothelial Growth Factor in Cyclosporin A-Induced Gingival Overgrowth in Rats

BACKGROUND

Gingival overgrowth is a side effect associated with cyclosporin A (CsA) therapy. The lesion is characterized by increased epithelial thickness, enlargement of connective tissue, and increased vascularization. The aim of this experimental study was to examine the role of vascular endothelial growth factor (VEGF) in the pathogenesis of CsA-induced gingival overgrowth.

METHODS

Twenty male Wistar rats were divided into two groups of 10 animals each. For the development of gingival overgrowth, one group received CsA therapy subcutaneously in a daily dose of 10 mg/kg for 60 days, and the other group was used as a control. At the end of the experimental period, rats were subsequently decapitated, and the mandibles with the surrounding gingiva and soft tissue were removed. Half of each sample was used for histomorphometric analysis, and the other half was used for biochemical analysis. Histomorphometric analysis included the measurements of the number and diameter of blood vessel profiles under a microscope, and biochemical analysis included the assessment of VEGF concentration by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The histomorphometric findings showed that the number of blood vessel profiles increased in the CsA group compared to the control group (P <0.001), although the increase in the diameter of blood vessel profiles was not significant (P >0.05). The biochemical findings showed that in vivo VEGF expression was higher in the CsA group compared to the control group (P <0.001).

CONCLUSION

The results of this study suggest that increased VEGF expression may be associated with the pathogenesis of CsA-induced gingival overgrowth.

Morphological and molecular analysis of idiopathic gingival fibromatosis: a case report

AIM

We analyse a case of idiopathic gingival overgrowth using morphological and molecular methods. As this overgrowth involves collagen accumulation in the gingival connective tissue, we measured the collagen turnover to clarify the pathogenic mechanisms potentially involved.

MATERIALS AND METHODS

The patient was a 29-year-old Italian woman with enlargement of the gingivae throughout the entire mandible and maxilla. Morphological analyses were carried out on haematoxylin-eosin and Sirius red-stained paraffin-embedded gingival sections. mRNA levels of collagen type I and III, matrix metalloproteinase (MMP)-1, transforming growth factor-beta1 and lysyl hydroxylase (LH)2b were determined by RT-PCR on cultured gingival fibroblasts and compared with healthy control fibroblasts. Interstitial collagen and MMP-1 content in the supernatants were assessed, respectively, by dot blot and SDS zymography.

RESULTS AND CONCLUSIONS

In Sirius red-stained sections of the patient's overgrown gingivae, interstitial collagen content was 29% higher than controls. Her gingival fibroblasts had higher collagen type I, MMP-1 and LH2b gene expression and unmodified interstitial collagen, type I protein levels in the supernatants. These findings would seem to suggest that in this case collagen accumulation in the gingival connective tissue was not associated with increased synthesis and decreased degradation.

Diltiazem did not induce gingival overgrowth in rats: a clinical, histological and histometric analysis

The administration of calcium channel blockers has been associated with gingival overgrowth. However, there are few studies in humans or animals that evaluated the effect of diltiazem on gingival tissues. The present study assessed the influence of diltiazem, at different dosages and treatment duration, on gingival tissues of rats, using clinical, histological and histometric analyses. Eighty young male rats were separated into eight groups according to the dosage and duration of treatment. Rats were treated for 20 or 40 days with a daily subcutaneous injection of 5, 20 or 50 mg/kg of body weight of diltiazem. The results confirmed that diltiazem did not induce gingival overgrowth in rats. For all animals, the evaluation did not show gingival alterations regardless of the dosages and periods of treatment. The histometric analysis showed no significant change in the area of epithelium and connective tissues, although after 40 days of treatment a decrease in the area of connective tissue was observed, without statistically significant difference from control groups. Within the limits of this study, we suggest that diltiazem did not induce gingival overgrowth.

Separate functions of gelsolin mediate sequential steps of collagen phagocytosis

Collagen phagocytosis is a critical mediator of extracellular matrix remodeling. Whereas the binding step of collagen phagocytosis is facilitated by Ca2+-dependent, gelsolin-mediated severing of actin filaments, the regulation of the collagen internalization step is not defined. We determined here whether phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] regulation of gelsolin is required for collagen internalization. In gelsolin null fibroblasts transfected with gelsolin severing mutants, actin severing and collagen binding were strongly impaired but internalization and actin monomer addition at collagen bead sites were much less affected. PI(4,5)P2 accumulated around collagen during internalization and was associated with gelsolin. Cell-permeable peptides mimicking the PI(4,5)P2 binding site of gelsolin blocked actin monomer addition, the association of gelsolin with actin at phagosomes, and collagen internalization but did not affect collagen binding. Collagen beads induced recruitment of type 1 gamma phosphatidylinositol phosphate kinase (PIPK1gamma661) to internalization sites. Dominant negative constructs and RNA interference demonstrated a requirement for catalytically active PIPK1gamma661 for collagen internalization. We conclude that separate functions of gelsolin mediate sequential stages of collagen phagocytosis: Ca2+-dependent actin severing facilitates collagen binding, whereas PI(4,5)P2-dependent regulation of gelsolin promotes the actin assembly required for internalization of collagen fibrils.

Clinical trial evaluating the efficacy and safety of cyclosporine in dogs with atopic dermatitis

OBJECTIVE

To determine efficacy and safety of cyclosporine in the treatment of atopic dermatitis among dogs in North America.

DESIGN

Randomized controlled (phase 1) and open-label (phase 2) trials.

ANIMALS

268 dogs with atopic dermatitis.

PROCEDURE

In phase 1, dogs were randomly assigned to be treated with cyclosporine (5 mg/kg [2.3 mg/Ib], PO, q 24 h) or a placebo. In phase 2, all dogs were treated with cyclosporine for 16 weeks. Frequency of cyclosporine administration was decreased if dogs improved clinically.

RESULTS

At the end of phase 1, canine atopic dermatitis extent and severity index (CADESI) scores for dogs treated with cyclosporine were significantly lower than scores for control dogs. Percentage of dogs with severe pruritus decreased from 67% to 16% for the cyclosporine group but from 66% to only 61% for the control group. During phase 2, cyclosporine dosage was decreased to every-other-day administration in 39% of the dogs after 4 weeks. After 12 weeks, 22% of the dogs were treated twice weekly and 36% were treated every other day. After 16 weeks, CADESI score had decreased > 50% in 68% of the dogs and 47% of dogs had no or mild pruritus. The most frequent adverse reactions were gastrointestinal tract signs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that cyclosporine is efficacious for the treatment of atopic dermatitis in dogs and that frequency of cyclosporine administration can be reduced following an initial induction period. The drug was well tolerated.

Effects of long-term cyclosporin therapy on gingiva of rats: analysis by stereological and biochemical estimation

Cyclosporin A (CsA) is used as an immunosuppressive agent and its prominent side effect is the induction of gingival overgrowth, which remains a significant problem. The risk factors appraised include the duration of treatment. However, there are no stereological and biochemical studies exploring the effects of long-term CsA therapy on gingival tissue. The purpose of the present study was to investigate the level of TGF-beta1 in saliva and describe the densities of fibroblasts and collagen fibers in the gingival tissue of rats treated with CsA for long periods. Rats were treated for 60, 120, 180 and 240 days with a daily subcutaneous injection of 10 mg/kg of body weight of CsA. At the end of the experimental periods, saliva was collected for the determination of TGF-beta1 levels. After histological processing, the oral epithelium and the connective tissue area were measured as well as the volume densities of fibroblasts (Vf) and collagen fibers (Vcf). After 60 and 120 days of CsA treatment, there was a significant increase in Vf and Vcf as well as a significant increase in TGF-beta1 levels. After 180 and 240 days, reduction in the gingival overgrowth associated with significant decreases in the level of TGF-beta1, and also decreased Vf and Vcf, were observed. The data presented here suggest that after long-term therapy, a decrease in TGF-beta1 levels occurs, which might contribute to an increase in the proteolytic activity of fibroblasts in the gingiva, favoring the normality of extracellular matrix synthesis.