Site-specific variations in metabolism by human fibroblasts exposed to nifedipine in vitro

Nifedipine and Cyclosporin Affect Fibroblast Calcium and Gingiva

It has been stated that cyclosporin and nifedipine produce gingival overgrowth. However, the specific pathogenic mechanism remains uncertain. We used an experimental rat model to test the hypothesis that changes in collagen metabolism and numbers of gingival blood vessels are not mediated by intracellular calcium concentration (ratiometric Fura-2 AM measurement) in gingival fibroblasts. In the cyclosporin group, both width (364.2 ± 67.5 μm) and microvessel density (number of vessels/mm2, stained with anti-CD34 antibody) (41.6 ± 5.1) of gingiva were statistically different when compared with those in the control group (width = 184.3 ± 35.2 μm, microvessel density = 19.6 ± 2.4). The nifedipine group showed the highest content of collagen (proportion of total stroma occupied by collagen, stained with Picro-Mallory) (nifedipine group = 66.3 ± 9.4, cyclosporin group = 55.2 ± 7.9, control group = 30.1 ± 10.2). Freshly cultured fibroblasts from the cyclosporin group exhibited higher ratiometric values of fluorescence than did both the control and nifedipine groups (p = 0.03). Our results support the hypothesis that changes in gingival collagen metabolism are not mediated by calcium intracellular oscillations.

Effects of nifedipine and interleukin-1alpha on the expression of collagen, matrix metalloproteinase-1, and tissue inhibitor of metalloproteinase-1 in human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Nifedipine-induced gingival overgrowth is known to be characterized by fibrosis and some degree of inflammation. However, the molecular mechanism of the fibrosis is not fully understood. The purpose of this study was to investigate in vitro the effects of nifedipine and interleukin-1alpha on the molecules involved in fibrosis, namely type I collagen, matrix metalloproteinase-1 (MMP-1), and tissue inhibitor of metalloproteinase-1 (TIMP-1).

MATERIAL AND METHODS

Four human gingival fibroblast strains, derived from four healthy volunteers, were cultured in media containing nifedipine (1 microg/ml), with or without interleukin-1alpha (0.05 ng/ml). The mRNAs of type I collagen, MMP-1, and TIMP-1 were measured by reverse transcription-polymerase chain reaction (RT-PCR). The proteins of MMP-1 and TIMP-1 were examined by enzyme-linked immunosorbent assay (ELISA), and the ratios of MMP-1 to TIMP-1 proteins were calculated.

RESULTS

The mRNA expression of type I collagen showed no significant change. Both mRNA expression and protein production of MMP-1 were up-regulated by interleukin-1alpha, either alone or in combination with nifedipine, whereas those of TIMP-1 were up-regulated by nifedipine alone or in combination with interleukin-1alpha. The ratio of MMP-1 to TIMP-1 was not changed by nifedipine alone, but it was increased by interleukin-1alpha alone or in combination with nifedipine. However, in two of the four cell strains tested, nifedipine reduced the ratio of MMP-1 to TIMP-1 compared with that for interleukin-1alpha alone.

CONCLUSION

These results suggest that nifedipine may predispose to fibrosis in some individuals in situations where interleukin-1 levels are raised.

Synergism between nifedipine and cyclosporine A on the incorporation of [35S]sulfate into human gingival fibroblast cultures in vitro

BACKGROUND AND OBJECTIVE

We assessed the effects of cyclosporine A and nifedipine on the in vitro incorporation of [(35)S]sulfate into gingival fibroblast cell cultures derived from responder and nonresponder subjects who had received an organ transplant followed by a therapeutic regimen using a combination of those drugs.

MATERIAL AND METHODS

Gingival fibroblasts were isolated from responder and nonresponder subjects and maintained in vitro. Prior to cell harvest, gingival interleukin-1beta concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Cells were untreated or exposed to either 10(-7)-10(-10) m nifedipine or 100-500 ng/ml cyclosporine A. Incorporation of [(3)H]proline or [(35)S]sulfate into the cell cultures was determined by liquid scintillation analysis. In addition, the effects of 400 ng/ml cyclosporine A + 10(-7) m nifedipine and 400 ng/ml cyclosporine A + 10(-10) m nifedipine on incorporation of [(35)S]sulfate into the cell cultures was determined. Data were compared by factorial analysis of variance (anova) and a posthoc Tukey's test.

RESULTS

Gingiva from responders contained significantly more interleukin-1beta than gingiva from nonresponders (p < 0.01). The cell cultures derived from responders incorporated significantly more [(35)S]sulfate than those derived from nonresponders following exposure to either cyclosporine A or 10(-7) m nifedipine. In addition, the exposure of fibroblasts derived from gingival overgrowth to either 400 ng/ml cyclosporine A + 10(-7) m nifedipine or 400 ng/ml cyclosporine A + 10(-10) m nifedipine significantly increased or decreased, respectively, the incorporation of [(35)S]sulfate into the cultures.

CONCLUSION

The therapeutic combination of cyclosporine A and nifedipine could be a significant risk factor for gingival overgrowth in subjects susceptible to either agent. The mechanism for overgrowth could include edema secondary to increased sulfated-glycosaminoglycan (sGAG) synthesis by fibroblasts, but further investigation is required.

Cyclosporin A specifically affects nuclear PLCbeta1 in immunodepressed heart transplant patients with gingival overgrowth

One of the most commonly observed adverse effects of cyclosporin A (CsA) is the development of gingival overgrowth (GO). Fibroblasts are involved in GO, but the question why only a percentage of patients undergoing CsA treatment shows this side-effect remains unanswered. In a previous study, CsA has been demonstrated to induce over-expression of phospholipase C (PLC) beta(1) in fibroblasts of patients with clinical GO, in cells from both enlarged and clinically healthy gingival sites. In this work, we assessed the expression of PLCbeta isoforms to investigate whether the exaggerated fibroblast response to CsA related to increased PLCbeta(1) expression could also be detected in CsA-treated patients without clinical signs of GO. Our results support the hypothesis of a multi-factorial origin of gingival overgrowth, including specific changes within the gingival tissues orchestrating fibroblastic hyper-responsiveness as a consequence of a long-term in vivo exposure to cyclosporin A.

Effect of Tranilast on Matrix Metalloproteinase-1 Secretion From Human Gingival Fibroblasts In Vitro

BACKGROUND

Some drugs such as phenytoin, calcium blockers, or cyclosporins are known to cause gingival fibrous hyperplasia, an unwanted side effect. Decreased collagen catabolism in overgrown gingival tissue has been proposed as one of the reasons causing the disease. The effect of tranilast, which suppresses collagen synthesis and cell proliferation, on matrix metalloproteinase (MMP-1) secretion from human gingival fibroblast, was studied in vitro.

METHODS

Human gingival fibroblasts were cultured from specimens taken from healthy, periodontal, and overgrown gingival tissues. The effects of tranilast on cell proliferation and MMP-1 secretion from gingival fibroblast were assessed. Inhibitory effect of transforming growth factor (TGF)-beta secretion from gingival fibroblast by tranilast was also evaluated.

RESULTS

Tranilast did not interfere with cell proliferation at the low concentrations. MMP-1 concentration significantly increased at the lower doses of tranilast up to about 2-fold compared to controls (P < 0.05). In contrast, higher doses of tranilast significantly decreased activity to 30% and 20%, respectively. MMP-1 secretion was inhibited significantly by phenytoin, nifedipine, and cyclosporin A and the depressed MMP-1 recovered to the control level with tranilast. The amount of secretion from normal and periodontitis gingival fibroblast specimens did not differ, but that from the overgrown gingiva was significantly less than the other types. Moreover, TGF-beta secretion was significantly inhibited by 300 microM of tranilast.

CONCLUSIONS

Tranilast upregulates the expression of type 1 collagenase suppressed by gingival overgrowth-inducing drugs, and inhibits TGF-beta secretion from gingival fibroblasts. Therefore, tranilast could be considered as an agent for controlling gingival over-growth.

Influence of nifedipine on gingiva of Wistar rats

Noninflammatory hyperplastic growth of gingiva induced by calcium channel blockers, mostly nifedipine, is often seen in everyday dental practice. In order to establish an association of nifedipine and gingival hyperplasia, experimental model was used. Wistar rats were given water solution of nifedipine in different daily doses, using specially designed cannula. At the beginning of the experiment, before the application of nifedipine and in the determined time periods, gingival volume was measured. The volume of lower incisors interdental central papillas, represented multiplied values of vertical hight, mesio-distal width, and bucco-lingual depth, expressed in millimeters. The results indicated that gingival hyperplasia was more excessive in the experimental animals, which were given higher doses of the drug for longer time period. Nifedipine is a drug which induces gingival fibroblasts to produce higher quantity of collagen that causes gingival overgrowth.

Synergistic enhancement of collagenous protein synthesis by human gingival fibroblasts exposed to nifedipine and TNF-alpha in vitro

BACKGROUND

Gingival overgrowth occurs in patients receiving nifedipine. Gingival inflammation may be an etiologic factor.

METHODS

Gingival fibroblasts were either exposed to (i) 0-500 ng/ml TNF-alpha or 10(-7) M nifedipine or (ii) 0-500 ng/ml TNF-alpha + 10(-7) M nifedipine for 7 days. 3H-proline was used to quantify collagenous protein synthesis.

RESULTS

Both TNF-alpha and 10(-7) M nifedipine significantly decreased cell proliferation, and 10(-7) M nifedipine + 500 ng/ml TNF-alpha reversed these effects. Collagenous protein synthesis was significantly reduced by TNF-alpha and was significantly enhanced by either 10(-7) M nifedipine or 5-500 ng/ml TNF-alpha + 10(-7) M nifedipine.

CONCLUSIONS

Our data report that nifedipine reverses the primary effects of TNF-alpha on collagenous protein synthesis. Patients with gingivitis could be susceptible to gingival overgrowth during nifedipine therapy as a result of synergistic effects of these agents on fibroblast metabolism, which occurs irrespective of reduced cell numbers.

Ultrastructure of the gingiva in cardiac patients treated with or without calcium channel blockers

OBJECTIVES

In the last few years, several studies have suggested that periodontal diseases are related to the development of atherosclerosis and its complications. Our objective was to study the ultrastructural morphology of the gingiva from cardiac patients, some of whom were treated and some not with calcium channel blockers compared to a control group.

MATERIAL AND METHODS

Fifty-five patients were studied and grouped in the following way: (a) healthy group (HG) (n=12) healthy patients with at least two pockets between 3 and 5 mm; (b) cardiac group (CG) (n=12) patients with cardiac disease untreated with calcium channel blockers; (c) diltiazem group (DG) (n=13) cardiac patients treated with diltiazem; (d) nifedipine group (NG) (n=18) cardiac patients treated with nifedipine.

RESULTS

Ultrastructural studies in the CG showed inflammatory cells, collagen fibers disruption and a more extended morphologically compromised fibroblast mitochondria. Morphometric studies in CG showed mitochondria that were impaired in number but increased in volume, suggesting metabolic cell suffering. In DG and NG, morphometric data were similar to HG. The presence of myofibroblasts and collagen neosynthesis was detected in DG and NG.

CONCLUSIONS

Our data showed differences in the ultrastructure of the gingival fibroblasts between the studied groups; the DG and NG showed features that could be interpreted as an attempt to restore the cellular metabolic function.

Prevalence and risk of gingival enlargement in patients treated with anticonvulsant drugs

BACKGROUND

Predictors of gingival enlargement in patients treated with anti-epileptics have not been previously assessed. This study was conducted to determine, with the aid of two indices that score vertical and horizontal overgrowth, the prevalence and risk factors for gingival enlargement in patients treated with phenytoin and other anticonvulsant drugs.

MATERIALS AND METHODS

A cross-sectional study was conducted and data from 59 patients taking antiepileptics were compared with 98 controls. Gingival enlargement was evaluated with two indices to score vertical overgrowth [Gingival overgrowth index (GO] and horizontal overgrowth [Miranda-Brunet index (MB)]. Gingival index, plaque index, and probing depth were also evaluated.

RESULTS

The prevalence of gingival enlargement was significantly higher (P < 0.0001) for both indices in the anticonvulsants treated groups than in the control group. Gingival overgrowth was significantly higher for both indices in the phenytoin group than in the non phenytoin group. Among the possible risk factors, only the gingival index showed a significant association with gingival enlargement. For the MB index the risk of gingival enlargement (odds ratio) associated to phenytoin therapy and other anticonvulsants therapy were 52.6 (13.5-205) and 6.6 (1.5-28.2). Gingival index-adjusted odds ratios for the same drugs were 5.7 (1.3-24.7) and 18.1 (2-158), respectively. The concordance between GO and MB indices in the control group and in the phenytoin-group and non phenytoin-group showed a Kappa value of 0.773 and 0.697, respectively.

CONCLUSION

This study reports significant differences in the prevalence and severity of gingival overgrowth in two groups of patients, one treated with phenytoin, and another treated with other anticonvulsants. Gingival inflammation is a significant risk factor for gingival enlargement in these patients.

Prevalence and risk of gingival enlargement in patients treated with nifedipine

BACKGROUND

Gingival enlargement is a known side effect of nifedipine use. This study was conducted to determine the prevalence and risk factors for gingival enlargement in nifedipine-treated patients.

METHODS

A cross-sectional study was conducted in a primary care center. Data from 65 patients taking nifedipine were compared with 147 controls who had never received the drug. All patients were examined for the presence of gingival enlargement using 2 different indices: vertical gingival overgrowth index (GO) in 6 points around each tooth, and horizontal MB index in the interdental area. Gingival index, plaque index, and probing depth were also evaluated.

RESULTS

The prevalence of gingival enlargement was significantly higher in nifedipine-treated cases than in controls (GO index, 33.8% versus 4.1%; MB index, 50.8% versus 7.5%, respectively). Higher gingival and plaque indices were observed in patients taking nifedipine. Among the possible risk factors, only the gingival index showed a significant association with gingival enlargement. The risk (odds ratio [OR]) of gingival enlargement associated with nifedipine therapy was 10.6 (3.8-29.1) for the GO index and 14.4 (6-34.6) for the MB index. Gingival index-adjusted ORs were 9.6 (3.3-28.1) and 9.7 (3.9-23.3), respectively. In the subset of high nifedipine exposure patients, the odds ratio for gingival enlargement increased to 17.4 (5.3-56.3) for the GO index and 23.6 (7.7-72.3) for the MB index. The concordance between GO and MB indices showed a kappa value of 0.689 in controls and 0.642 in patients treated with nifedipine.

CONCLUSIONS

Patients taking nifedipine are at high risk for gingival enlargement, and gingivitis acts as a predisposing factor.

Cyclosporin A upregulates phospholipase C beta1 in fibroblasts from gingival overgrowth

BACKGROUND

In an attempt to evaluate the influence of cyclosporin A (CsA) on fibroblast metabolism, the phospholipase C beta1, (PLC beta1) nuclear expression was evaluated in fibroblasts from heart transplantation patients treated with CsA who exhibited gingival overgrowth (GO) and from controls.

METHODS

PLC beta1 was assessed by immunoblotting and immunocytochemistry means.

RESULTS

Findings did not show any difference in terms of PLC beta1 expression between the 2 groups when fibroblasts were incubated in media without CsA, while the addition of CsA highly stimulated the fibroblasts from CsA-treated patients compared to controls. The abnormal fibroblastic response in CsA-treated patients was detected both in cells from enlarged gingival sites and in cells from clinically healthy gingival sites.

CONCLUSIONS

These results do not explain whether the exaggerated reactivity to in vitro CsA is the consequence of a genetically transmitted susceptibility to CsA that identifies those subjects at risk for developing GO, or whether it is a secondary effect of the long-term in vivo exposure to CsA. However, the present data underline the lack of any close relationship between enhanced fibroblast activity and clinical signs of GO and support the hypothesis that some other factors, together with CsA, are involved in the pathogenesis of CsA-induced GO.

Keratinocyte growth factor is upregulated by the hyperplasia-inducing drug nifedipine

Keratinocyte growth factor (KGF) is the seventh member of the fibroblast growth factor (FGF) family. It is produced by mesenchymal cells and its activity is specific for epithelial cells, controlling epithelial homeostasis and wound repair in a paracrine manner. Although KGF has been implicated in a number of hyperplastic pathologies, it has not previously been investigated in gingival hyperplasia (GH), an adverse side-effect of three pharmacologically different types of drugs, including the anti-hypertensive drug nifedipine (NIF). The mechanism by which NIF causes GH is not yet known, but we have recently shown that KGF mRNA transcripts are elevated in drug-induced GH in vivo (manuscript submitted). It is therefore possible that the action of NIF is mediated via KGF and, in the present study, using the enzyme-linked immunosorbent assay (ELISA) and the semi-quantitative reverse transcribed-polymerase chain reaction (RT-PCR), we found that NIF upregulates KGF secretion and gene transcription by gingival fibroblasts in vitro. Our results thus suggest that KGF may have an important role in the molecular pathology of GH in vivo.

Medication induced gingival overgrowth

A number of idiopathic, pathological and pharmacological reactions may result in an overgrowth of the gingiva. This review concentrates on those overgrowths associated with various pharmacological agents. The pharmaco-kinetics and side effects of each drug associated with gingival overgrowth are discussed along with the clinical and histological features and treatment. By examining the possible pathogeneses for these overgrowths we propose a unifying hypothesis for the causation based around inhibition of apoptosis and decreased collagenase activity modulated by cytoplasmic calcium.