Apoptosis and Expression of Caspase-3 in Cyclosporin-Induced Gingival Overgrowth

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

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

Synthesis, Characterization, and In Vivo Study of Some Novel 3,4,5-Trimethoxybenzylidene-hydrazinecarbothioamides and Thiadiazoles as Anti-Apoptotic Caspase-3 Inhibitors

The present study aims to discover novel derivatives as antiapoptotic agents and their protective effects against renal ischemia/reperfusion. Therefore, a series of new thiadiazole analogues 2a–g was designed and synthesized through cyclization of the corresponding opened hydrazinecarbothioamides 1a–g, followed by confirmation of the structure via spectroscopic tools (NMR, IR and mass spectra) and elemental analyses. The antiapoptotic activity showed alongside decreasing of tissue damage induced by I/R in the kidneys of rats using N-acetylcysteine (NAC) as an antiapoptotic reference. Most of the cyclized thiadiazoles are better antiapoptotic agents than their corresponding opened precursors. Particularly, compounds 2c and 2g were the most active antiapoptotic compounds with significant biomarkers. A preliminary mechanistic study was performed through caspase-3 inhibition. Compound 2c was selected along with its corresponding opened precursor 1c. An assay of cytochrome C revealed that there is an attenuation of cytochrome C level of about 5.5-fold, which was better than 1c with a level of 4.1-fold. In caspases-3, 8 and 9 assays, compound 2c showed more potency and selectivity toward caspase-3 and 9 compared with 1c. The renal histopathological investigation indicated normal renal tissue for most of the compounds, especially 2c and 2g, relative to the control. Finally, a molecular docking study was conducted at the caspase-3 active site to suggest possible binding modes.

Local and Systemic Effects of Cyclosporine A on the Severity of Gingival Overgrowth in Post-Transplant Renal Patients

Background:

Cyclosporine A (CsA) is a potent immunosuppressant widely used to prevent renal post transplantation rejection. Gingival overgrowth (GO) is among various side effects of the long-term administration of CsA. Up to 90% of the patients under CsA therapy has been reported to develop CsA-induced GO.

Objectives:

The aim of the present prospective pilot study is to determine the local and systemic effects of Cyclosporine A (CsA) on the severity of gingival overgrowth and its relationship with periodontal parameters in post-transplant renal patients

Methods:

Twenty post-transplant renal patients, 12 females and 8 males, presenting gingival overgrowth were selected from Rizk Hospital’s clinic in Beirut. Patient’s CsA plaque levels were evaluated when CsA is administered by syrup and capsules mode. Periodontal parameters including gingival overgrowth, papillary bleeding, plaque and gingival indices were assessed for all patients.

Results:

Plaque concentration CsA levels, when administered in syrup mode, affected significantly the severity of gingival overgrowth as opposed to the administration by capsule mode. Significant correlations between severity of gingival overgrowth on one hand and plaque index, gingival index, and papillary bleeding index on the other hand were only observed in the Capsule group but not in the syrup group. A significant relationship was established between the severity of gingival overgrowth and all periodontal parameters (gingival, papillary and plaque).

Conclusion:

The present study underlines CsA dental plaque local effect, as a co-factor, in the development of gingival overgrowth. Cyclosporine plaque accumulation acts as a reservoir in the gingival inflammation and the periodontal indices seem to be the most accurate parameters associated with gingival overgrowth severity. Plaque CsA concentrations could be considered as a risk factor for inflammation and gingival overgrowth depending on CsA delivery mode in renal transplant patients.

Design, Synthesis, Molecular Docking, Antiapoptotic and Caspase-3 Inhibition of New 1,2,3-Triazole/Bis-2(1H)-Quinolinone Hybrids

A series of novel 1,2,3-triazoles hybridized with two quinolin-2-ones, was designed and synthesized through click reactions. The structures of the synthesized compounds were elucidated by NMR, IR, and mass spectra in addition to elemental analysis. The synthesized compounds were assessed for their antiapoptotic activity in testis, as testicular torsion is the main cause of male infertility. This effect was studied in light of decreasing tissue damage induced by I/R in the testis of rats using N-acetylcysteine (NAC) as an antiapoptotic reference. Compounds 6a-c were the most active antiapoptotic hybrids with significant measurements for malondialdehyde (MDA) and total antioxidant capacity (TAC) and the apoptotic biomarkers (testicular testosterone, TNFα, and caspase-3) in comparison to the reference. A preliminary mechanistic study was performed to improve the antiapoptotic activity through caspase-3 inhibition. A compound assigned as 6-methoxy-4-(4-(((2-oxo-1,2-dihydroquinolin-4-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)quinolin-2(1H)-one (6c) was selected as a representative of the most active hybrids in comparison to NAC. Assay of cytochrome C for 6c revealed an attenuation of cytochrome C level about 3.54 fold, comparable to NAC (4.13 fold). In caspases-3,8,9 assays, 6c was found to exhibit more potency and selectivity toward caspase-3 than other caspases. The testicular histopathological investigation was carried out on all targeted compounds 6a-g, indicating a significant improvement in the spermatogenesis process for compounds 6a-c if compared to the reference relative to the control. Finally, molecular docking studies were done at the caspase-3 active site to suggest possible binding modes. Hence, it could conceivably be hypothesized that compounds 6a-c could be considered good lead candidate compounds as antiapoptotic agents.

Phenytoin-induced gingival overgrowth caused by death receptor pathway malfunction

OBJECTIVE

In this study, we investigated the role of phenytoin (PHT) in death receptor-induced apoptosis of gingival fibroblasts to clarify the mechanism of PHT-induced gingival overgrowth.

METHODS

Human gingival fibroblasts were cultured to semiconfluence and treated with PHT (0.025, 0.1, 0.25, and 1.0 μM) for 48 h, and then, the apoptotic cell numbers were relatively determined by absorptiometry. After 24 h of 0.25 μM PHT treatment, caspase activity was measured by absorptiometry, apoptotic and cell cycle phase distribution was analyzed by flow cytometry, expression levels of apoptotic genes were quantified by real-time qPCR, and expression of apoptotic proteins was detected by Western blot analysis. After 48 h of 0.25 μM PHT treatment, appearance of apoptotic cells was detected by TUNEL assay.

RESULTS

PHT treatment decreased the proportion of apoptotic cells in gingival fibroblasts compared to a serum-free control culture in response to the protein changes as follows: PHT upregulated c-FLIP and, in turn, downregulated FADD, caspase-8, and caspase-3; PHT upregulated c-IAP2 and downregulated TRAF2; PHT downregulated caspase-9 and caspase-3 via decreased RIPK1 activity and increased Bcl-2 activity.

CONCLUSION

PHT-induced gingival overgrowth may result from the above-mentioned mechanisms involving apoptosis inhibition in gingival fibroblasts.

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

BACKGROUND AND PURPOSE

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

EXPERIMENTAL APPROACH

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

KEY RESULTS

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

CONCLUSIONS AND IMPLICATIONS

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

Effect of periodontal treatment in renal transplant recipients

OBJECTIVE

To evaluate the effect of periodontal treatment on gingival overgrowth in a group of renal transplant patients.

SUBJECTS AND METHODS

Twenty-five renal transplant recipients receiving immunosuppressive therapy with cyclosporine A (CsA) were randomly assigned to 2 groups. Group 1 (n = 15) included patients who had been specifically referred to a dental clinic to prevent gingival overgrowth and were given full periodontal therapy. Group 2 (n = 10) was comprised of patients who did not receive any professional periodontal cleaning. Patients from both groups were examined to determine their periodontal status before and after 3, 6 and 12 months in terms of their plaque index, gingival index and gingival overgrowth. During the examination, their overall health was stable.

RESULTS

For group 1, the scores were 1.89 (baseline), 0.98 (6 months) and 0.56 (12 months), and hence there were significant reductions (p = 0.0001). The gingival indices were 1.71 (baseline), 0.76 (6 months) and 0.35 (12 months), and the reductions were also significant (p = 0.0001). A significant association was observed between poor oral hygiene and the degree of gingival overgrowth. The 1-year post-treatment follow-up showed that patients in group 1 did not develop gingival overgrowth due to the use of CsA as group 2 did without prior periodontal therapy.

CONCLUSION

Oral hygiene status was the most important variable related to the development and degree of gingival overgrowth due to the use of CsA.

The role of inflammation and apoptosis in cyclosporine A-induced gingival overgrowth

Cyclosporin A(CsA) - induced gingival overgrowth(GO) is a current problem of tissue-specific mechanism which is still incompletely explained. The apoptotic process has been of particular interest like a new concept in the etiology of this unwanted effect. The aim of our study was to detect the level of apoptosis, expression bcl-2 and p53, associated with the different doses of CsA. in gingival stroma. A cohort of 84 kidney transplant recipients was divided into four subgroups based on average daily dose of therapeutically applied CsA (Neoral®), (100 mg, 125 mg, 150 mg and 175 mg). The control group consisted of 21 patients, clinically diagnosed with periodontitis, who were not subjected to any medicamentous treatment causing gingival overgrowth. The following indexes were analyzed: plaque index (PI), index of gingival inflammation (GI) according to Loe-Silnes, and gingival overgrowth index (GOI) according to MacGaw et al. The tissue samples were subjected to a semiquantitative analysis to detect apoptotical cells and immunohistochemically stained to detect the expression of the bcl-2 and p53 proteins. The difference in percentage of apoptotic cells between the group taking 175 mg and other subgroups, as well as the control group was statistically significant (p<0.05). There was a significant difference in percentage of expression bcl-2 between the 175 mg group compared to the other three subgroups and the control (p=0.001). However, a statistically significant positive correlation between the medicament dose, p53, apoptosis, and bcl-2 was registered (p<0.05). Inflammation plays the most important role in the induction of apoptosis and proliferation in gingival tissues.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Differential gene and protein expression of tissue inhibitors of metalloproteinases (TIMP)-3 and TIMP-4 in gingival tissues from drug induced gingival overgrowth

OBJECTIVES

The purpose of this study was to analyse mRNA expression and protein localization of tissue inhibitors of metalloproteinases (TIMP)-3 and TIMP-4 in gingival tissues removed from drug (calcium-channel blocker) induced gingival overgrowth and periodontitis patients.

DESIGN

Employing RT-PCR, we evaluated TIMP-3 and TIMP-4 mRNA levels of 20 human gingival tissue samples taken from patients suffering gingival overgrowth (GO) and periodontitis (P). Then, using immunohistochemistry we investigated the TIMP-3 and TIMP-4 protein localization of five sample tissues from each group.

RESULTS

TIMP-4 mRNA levels in GO-gingiva tended to be lower than in P-gingiva but the results differed little (p = 0.22). Varying degrees of inflammation in the protein localization of TIMP-3 and TIMP-4 were found. TIMP-4 immunoreactivity (IR) was weak in the endothelial cells, fibroblasts, epithelial basal and parabasal cells while the degree of inflammation differed as well. TIMP-3 and TIMP-4 IR in inflammatory cells, including lymphocytes, plasma cells, and macrophages, were faint and intense respectively. For P-gingiva, both TIMP-3 and TIMP-4 IR expression was weak in the endothelial cells, fibroblasts, basal and parabasal epithelial layers. Expression of TIMP-3 was faint in the inflammatory cells, whereas TIMP-4 IR was strong.

CONCLUSION

Our findings suggest that TIMP-3 and TIMP-4 expression differs in GO and P-gingival tissues, both of which are potentially involved in pathogenesis.

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

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