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

Drug-Induced Gingival Overgrowth-Molecular Aspects of Drug Actions

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

Influence of mast cells in drug-induced gingival overgrowth

Mast cells (MCs) are multifunctional effector cells that were originally thought to be involved in allergic disorders. Now it is known that they contain an array of mediators with a multitude of effects on many other cells. MCs have become a recent concern in drug-induced gingival overgrowth (DIGO), an unwanted outcome of systemic medication. Most of the studies have confirmed the significant presence of inflammation as a prerequisite for the overgrowth to occur. The inflammatory changes within the gingival tissue appear to influence the interaction between the inducing drug and the fibroblast activity. The development of antibodies to MC-specific enzymes, tryptase and chymase, has facilitated the study of mast cells in DIGO. Many immunohistochemical studies involving MCs have been conducted; as a result, DIGO tissues are found to have increased the number of MCs in the gingiva, especially in the area of fibrosis. At the cellular level, gingival fibrogenesis is initiated by several mediators which induce the recruitment of a large number of inflammatory cells, including MCs. The purpose of this paper is to access the roles played by MCs in gingival overgrowth to hypothesize a relationship between these highly specialized cells in the pathogenesis of DIGO.

Immunohistochemical Evaluation of Ki-67 Expression and Apoptosis in Cyclosporin A-Induced Gingival Overgrowth

BACKGROUND

This study was planned to evaluate cell division rate and apoptosis by immunohistochemical and in situ hybridization techniques in cyclosporin A (CsA)-induced gingival overgrowth tissue samples to determine whether these processes played a role in the pathogenesis of this condition.

METHODS

Fourteen CsA-induced overgrowth tissues from renal transplant recipients, 10 control tissues from patients with plaque-induced gingivitis, and 14 control tissues from systemically and periodontally healthy subjects were evaluated. In patient groups, clinical periodontal recordings and tissue sampling were performed before initiation of any periodontal intervention. Numbers of Ki-67-positive cells/field and apoptotic cells/field in formalin-fixed/paraffin-embedded tissue sections were determined. Data were evaluated by one-way analysis of variance, post hoc Sidak test with modified Bonferroni correction, and Pearson correlation analysis. Three phenytoin- and five nifedipine-induced overgrowth tissues were also processed in the same way, and findings in these tissue specimens were evaluated as case series.

RESULTS

The number of keratinocytes was significantly greater in the CsA-induced gingival overgrowth group than in the healthy control group (P <0.05). Cells labeled by in situ end labeling, namely the apoptotic cells, were significantly fewer in the CsA group than in the gingivitis and healthy control groups (P <0.01). Overall, statistically significant positive correlations were found between the numbers of Ki-67-positive cells and probing depth and hyperplastic, bleeding, and plaque indices (P <0.01). Phenytoin and nifedipine samples exhibited obviously higher expression of Ki-67-positive cells than the CsA, gingivitis, and healthy control groups.

CONCLUSION

Our findings suggest that decreased apoptosis may have a more prominent role than increased cell division in the pathogenesis of CsA-induced gingival overgrowth.

Upregulation of the Expression of Epidermal Growth Factor and Its Receptor in Gingiva Upon Cyclosporin A Treatment

BACKGROUND

To understand the roles of epidermal growth factor (EGF) and EGF receptor (EGF-R) in cyclosporin A (CsA)-induced gingival overgrowth, expression of EGF and EGF-R upon CsA treatment was examined in an oral epidermoid carcinoma cell line of humans (OECM-1) and in edentulous gingiva of rats.

METHODS

In vitro study: after CsA treatment, OECM-1 cells were harvested to evaluate their mRNA and protein expression of EGF and EGF-R with reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, and immunocytochemistry (ICC). In vivo study: 3 weeks after extraction of all maxillary molars, 20 male Sprague-Dawley rats were assigned to a CsA group (30 mg/kg, fed daily) and a control group. Five rats per group were sacrificed at weeks 1 and 4. Edentulous ridge specimens were obtained for evaluating their mRNAs and protein expression with RT-PCR, real-time RT-PCR, and immunohistochemistry (IHC). In both in vitro and in vivo experiments, the proliferating potential of epithelial cells was examined by the presence of proliferating cell nuclear antigen (PCNA).

RESULTS

In vitro: dose-dependently increased mRNA expression of EGF and EGF-R in OECM-1 cells was noted after CsA treatment. Protein expressions of EGF and EGF-R were higher in OECM-1 with CsA treatment than without CsA. In vivo: higher mRNA and protein expressions of EGF and EGF-R were also observed in the gingival tissues of CsA-treated rats. In both in vitro and in vivo experiments, greater PCNA expression after CsA treatment was demonstrated.

CONCLUSIONS

Higher expression of EGF and EGF-R upon CsA therapy was observed in OECM-1 epithelial cells of humans and in edentulous gingiva of rats. We suggest that CsA could upregulate gene and protein expression of EGF and EGF-R, and the upregulation may play a role in gingival overgrowth.

Plasminogen activators and plasminogen activator inhibitors in gingival crevicular fluid of cyclosporin A-treated patients

BACKGROUND

The plasminogen activator (PA) system plays many roles in the inflammatory process and tissue remodelling and repair and is considered to play a significant role in periodontal tissue destruction and healing. The aim of this study was to evaluate the role of the PA system in cyclosporin A (CsA)-induced gingival overgrowth in renal transplant patients.

METHODS

Eighteen renal transplant patients exhibiting moderate to severe CsA-induced gingival overgrowth, 10 other renal transplant patients receiving CsA therapy but showing no sign of CsA-induced gingival overgrowth (CsA-H), 16 chronic gingivitis patients (CG) and 16 systemically and periodontally healthy control subjects (H) were included in the study. Gingival crevicular fluid (GCF) samples were obtained from four randomly selected sites in each subject with the exception of the CsA-induced gingival overgrowth group, where four GCF samples were harvested from sites with severe overgrowth (CsA GO+) and from four sites without any gingival overgrowth (CsA GO-). The GCF levels of albumin, tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitor 1 (PAI-1) and plasminogen activator inhibitor 2 (PAI-2) were analysed by enzyme-linked immunosorbent assay. The results were tested for statistical differences.

RESULTS

In CsA GO+ sites t-PA levels were significantly elevated in comparison with gingivitis and healthy sites, while PAI-2 levels in these sites showed statistically significant differences only with CsA-H and gingivitis sites (p<0.05). The levels of t-PA and PAI-2 were significantly higher in CsA GO- sites compared with those of CsA-H, gingivitis and healthy sites (p<0.05). The levels of u-PA and PAI-1 failed to show significant differences between the study groups.

CONCLUSIONS

The findings of the present study indicate alterations in GCF t-PA and PAI-2 levels in CsA-induced gingival overgrowth and might suggest involvement of the plasminogen activating system in the pathogenesis of this side-effect of CsA therapy. However, to what extent these molecules contribute to the pathogenesis of CsA-induced gingival overgrowth remains to be determined.

Histologic features in primary cutaneous squamous cell carcinomas in immunocompromised patients focusing on organ transplant patients

BACKGROUND

In organ transplant recipients (OTR) there is an increased incidence of cutaneous squamous cell carcinomas (CSCC), and they may be aggressive.

OBJECTIVE

We wanted to determine whether any histologic features were characteristic or more common in CSCC of OTR.

METHODS

A total of 518 immunocompetent individuals with 601 primary CSCC were examined. Seventy-nine OTR with 231 primary CSCC, 53 renal OTR, 25 heart/heart lung OTR, and 1 liver OTR were examined.

RESULTS

In all patient populations, CSCC occurred dominantly in chronically sun-exposed skin. In OTR, however, a greater percentage occurred on the extremity, particularly the upper extremity, and they occurred at an earlier age. Features that were significantly more common in OTR were acantholytic changes, early dermal invasion, an infiltrative growth pattern with or without desmoplasia, and Bowen's disease with carcinoma. In OTR primary CSCC were also significantly deeper at time of diagnosis.

CONCLUSIONS

Our findings confirmed the association of ultraviolet radiation exposure with development of CSCC in OTR. The increased depth of the primary CSCC in OTR is surprising because these patients are followed closely for skin cancer compared with immunocompetent patients. The other morphologic features that were significantly more common in OTR may theoretically reflect not only the type of iatrogenic immunosuppression in these patients, but also other procarcinogenic effects of their medications.

Estrogen Suppression Induces Papillary Gingival Overgrowth in Pregnant Baboons

BACKGROUND

Alterations in sex steroids during pregnancy are associated with the development and exacerbation of reactive lesions involving the gingiva. Currently, few experimental animal models similar to humans are available to examine regulatory pathways involving sex steroids and the periodontium.

METHODS

In the present study, we used the baboon as a novel experimental model for the study of the regulatory actions of estrogen on the periodontium during pregnancy. Pregnant baboons (N = 5) were administered the potent, highly specific aromatase inhibitor CGS 20267 (2 mg/day subcutaneously) daily on days 60 through 165 of gestation (term = 184). Untreated females (N = 10) and females (5) concomitantly administered aromatase inhibitor and estradiol benzoate (2.0 mg/day each subcutaneously) served as controls. Gingival biopsies were taken between days 145 and 165 of gestation.

RESULTS

Administration of CGS 20267 in all females suppressed maternal serum concentrations of estradiol by 95% and induced the development of an exuberant papillomatous enlargement of the gingiva by gestational day 110, with the most prominent development involving the labial aspects of the anterior sextants. None of the untreated pregnant controls or females concomitantly administered aromatase inhibitor and estradiol benzoate developed gingival overgrowth. Thus, estradiol alone prevented the onset of gingival overgrowth induced by estrogen suppression. In all baboons, discontinuation of the aromatase inhibitor at time of cesarean section resulted in spontaneous regression and resolution of the papillomatous hyperplasia within 4 to 6 weeks. Clinically, the gingival papillary overgrowth was erythematous and edematous, with a propensity toward spontaneous subgingival hemorrhage. Histologically, the biopsy specimens demonstrated hyperplasia of the epithelium typified by mild hyperkeratosis, acanthosis, and elongation and isolated anastamoses of rete ridges. Subjacent to the intact epithelium was a loose connective tissue stroma with isolated areas of inflammatory cell infiltrate. Special stains verified the presence of isolated bacterial biofilms; however, no evidence of fungal filaments was present. Histological features suggestive of viral infection were notably absent in the epithelium. No evidence of viral particles or capsids was identified using transmission electron microscopy. Reverse transcription polymerase chain reaction analysis, using a panel of degenerate primers, was negative for papilloma family viruses.

CONCLUSIONS

These results are consistent with a significant role for estrogen during primate pregnancy in the regulation of cellular proliferation and differentiation within the gingiva. The baboon represents an important experimental model for studying the regulatory actions of estrogen on the periodontium during pregnancy.