Cyclosporine A promotes cell proliferation, collagen and α-smooth muscle actin expressions in rat gingival fibroblasts by Smad3 activation and miR-29b suppression

The yes-associated protein-1 (YAP1) inhibitor celastrol suppresses the ability of transforming growth factor β to activate human gingival fibroblasts

OBJECTIVE

To determine whether celastrol, an inhibitor of the mechanosensitive transcriptional cofactor yes-associated protein-1 (YAP1), impairs the ability of TGFβ1 to stimulate fibrogenic activity in human gingival fibroblast cell line.

DESIGN

Human gingival fibroblasts were pre-treated with celastrol or DMSO followed by stimulation with or without TGFβ1 (4 ng/ml). We then utilized bulk RNA sequencing (RNAseq), real-time polymerase chain reaction (RT-PCR), Western blot, immunofluorescence, cell proliferation assays to determine if celastrol impaired TGFβ1-induced responses in a human gingival fibroblast cell line.

RESULTS

Celastrol impaired the ability of TGFβ1 to induce expression of the profibrotic marker and mediator CCN2. Bulk RNAseq analysis of gingival fibroblasts treated with TGFβ1, in the presence or absence of celastrol, revealed that celastrol impaired the ability of TGFβ1 to induce mRNA expression of genes within extracellular matrix, wound healing, focal adhesion and cytokine/Wnt signaling clusters. RT-PCR analysis of extracted RNAs confirmed that celastrol antagonized the ability of TGFβ1 to induce expression of genes anticipated to contribute to fibrotic responses. Celastrol also reduced gingival fibroblast proliferation, and YAP1 nuclear localization in response to TGFβ1.

CONCLUSION

YAP1 inhibitors such as celastrol could be used to impair pro-fibrotic responses to TGFβ1 in human gingival fibroblasts.

Single-cell transcriptional profiling reveals immunomodulatory properties of stromal and epithelial cells in periodontal immune milieu with diabetes in rats

Periodontitis is the sixth major complication of diabetes. Gingiva, as an important component of periodontal tissues, serves as the first defense barrier against infectious stimuli. However, relatively little is known about cellular heterogeneity and cell-specific changes in gingiva in response to diabetes-associated periodontitis. To characterize molecular changes linking diabetes with periodontitis, we profiled single-cell transcriptome analyses of a total of 45,259 cells from rat gingiva with periodontitis under normoglycemic and diabetic condition. The single-cell profiling revealed that stromal and epithelial cells of gingiva contained inflammation-related subclusters enriched in functions of immune cell recruitment. Compared to normoglycemic condition, diabetes led to a reduction in epithelial basal cells, fibroblasts and smooth muscle cells in gingiva with periodontitis. Analysis of differentially expressed genes indicated that stromal and epithelial populations were reprogrammed towards pro-inflammatory phenotypes promoting immune cell recruitment in diabetes-related periodontitis. In aspect of immune cells, diabetes prominently enhanced neutrophil and M1 macrophage infiltration in periodontitis lesions. Cell-cell communications revealed enhanced crosstalk between stromal/epithelial cells and immune cells mediating by chemokine/chemokine receptor interplay in diabetes-associated periodontitis. Our findings deconvolved cellular heterogeneity of rat gingiva associated with periodontitis and diabetes, uncovered altered immune milieu caused by the disease, and revealed immunomodulatory functions of stromal and epithelial cells in gingival immune niche. The present study improves the understanding of the link between the diabetes and periodontitis and helps in formulating precise therapeutic strategies for diabetes-enhanced periodontitis.

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.

Mitochondrial Calcium Signaling as a Therapeutic Target for Alzheimer's Disease

Mitochondria absorb calcium (Ca2+) at the expense of the electrochemical gradient generated during respiration. The influx of Ca2+ into the mitochondrial matrix helps maintain metabolic function and results in increased cytosolic Ca2+ during intracellular Ca2+ signaling. Mitochondrial Ca2+ homeostasis is tightly regulated by proteins located in the inner and outer mitochondrial membranes and by the cross-talk with endoplasmic reticulum Ca2+ signals. Increasing evidence indicates that mitochondrial Ca2+ overload is a pathological phenotype associated with Alzheimer's Disease (AD). As intracellular Ca2+ dysregulation can be observed before the appearance of typical pathological hallmarks of AD, it is believed that mitochondrial Ca2+ overload may also play an important role in AD etiology. The high mitochondrial Ca2+ uptake can easily compromise neuronal functions and exacerbate AD progression by impairing mitochondrial respiration, increasing reactive oxygen species formation and inducing apoptosis. Additionally, mitochondrial Ca2+ overload can damage mitochondrial recycling via mitophagy. This review will discuss the molecular players involved in mitochondrial Ca2+ dysregulation and the pharmacotherapies that target this dysregulation. As most of the current AD therapeutics are based on amyloidopathy, tauopathy, and the cholinergic hypothesis, they achieve only symptomatic relief. Thus, determining how to reestablish mitochondrial Ca2+ homeostasis may aid in the development of novel AD therapeutic interventions.

miRNA-26-5p inhibits cyclosporine A-induced overgrowth of gingival fibroblasts by regulating PTEN/PI3K/AKT pathway

We evaluated the effect of cyclosporine A (CsA) administration on the level of miR-26-5p in rat gingival tissues and human gingival fibroblasts (HGFs) by qRT-PCR assay. Further, we conducted Western blotting and immunohistochemical analysis to assess the expressions of PTEN, PI3K, and p-AKT, and evaluated cell proliferation of HGFs by MTT assay. CsA treatment significantly downregulated the expressions of miR-26-5p and PTEN and upregulated the expressions of PI3K and p-AKT in both rat gingival tissues and HGFs. Overexpression of miR-26-5p inhibited CsA-induced overgrowth of HGFs, whereas knockdown of miR-26-5p promoted the overgrowth. PTEN knockdown not only promoted CsA-induced overgrowth of human HGFs but also reversed the repressive effects of miR-26-5p on CsA-induced overgrowth of HGFs. Our results revealed that miRNA-26-5p could repress CsA-induced overgrowth of human HGFs by regulating PTEN/PI3K/AKT pathway.

Galectin-8 mediates fibrogenesis induced by cyclosporine in human gingival fibroblasts

BACKGROUND AND OBJECTIVE

During cyclosporine-induced gingival overgrowth, the homeostatic balance of gingival connective tissue is disrupted leading to fibrosis. Galectins are glycan-binding proteins that can modulate a variety of cellular processes including fibrosis in several organs. Here, we study the role of galectin-8 (Gal-8) in the response of gingival connective tissue cells to cyclosporine.

METHODS

We used human gingival fibroblasts and mouse NIH3T3 cells treated with recombinant Gal-8 and/or cyclosporine for analyzing specific mRNA and protein levels through immunoblot, real-time polymerase chain reaction, ELISA and immunofluorescence, pull-down with Gal-8-Sepharose for Gal-8-to-cell surface glycoprotein interactions, short hairpin RNA for Gal-8 silencing and Student's t test and ANOVA for statistical analysis.

RESULTS

Galectin-8 stimulated type I collagen and fibronectin protein levels and potentiated CTGF protein levels in TGF-β1-stimulated human gingival fibroblasts. Gal-8 interacted with α5β1-integrin and type II TGF-β receptor. Gal-8 stimulated fibronectin protein and mRNA levels, and this response was dependent on FAK activity but not Smad2/3 signaling. Cyclosporine and tumor necrosis factor alpha (TNF-α) increased Gal-8 protein levels. Finally, silencing of galectin-8 in NIH3T3 cells abolished cyclosporine-induced fibronectin protein levels.

CONCLUSION

Taken together, these results reveal for the first time Gal-8 as a fibrogenic stimulus exerted through β1-integrin/FAK pathways in human gingival fibroblasts, which can be triggered by cyclosporine. Further studies should explore the involvement of Gal-8 in human gingival tissues and its role in drug-induced gingival overgrowth.

Assessing the effects of cyclosporine A on the osteoblastogenesis, osteoclastogenesis, and angiogenesis mediated by human periodontal ligament stem cells

BACKGROUND

This study was performed to investigate the effects of cyclosporine A (CsA) on the osteogenic differentiation, osteoclastogenic-supporting ability, and angiogenic potential of human periodontal ligament stem cells (hPDLSCs).

METHODS

hPDLSCs were isolated from the extracted teeth of orthodontic patients. Cell proliferation was assessed using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, and osteogenic differentiation was evaluated by alkaline phosphatase (ALP) and alizarin red (ARS) staining. Real-time polymerase chain reaction (PCR) was used to quantify transcripts. Tartrate-resistant acid phosphatase staining of bone marrow-derived macrophages (BMMs) and tube formation assays on human umbilical vein endothelial cells (HUVECs) were performed after treating cells with the conditioned media from CsA-exposed or non-exposed hPDLSCs. Signaling pathways mediating the angiogenic activity were investigated using western blotting.

RESULTS

CsA suppressed the proliferation of hPDLSCs but enhanced osteogenic differentiation as determined by ALP and ARS staining and PCR of osteogenic transcripts. The expressions of osteoclastogenic transcripts in hPDLSCs and the differentiation of BMMs treated with conditioned medium from CsA-exposed hPDLSCs were unaffected by CsA. However, the expressions of angiogenic transcripts and the transcripts known to support angiogenesis-phosphorylation of extracellular signal p-regulated kinase (ERK) and p38, and c-fos-were inhibited. Conditioned medium from CsA-exposed hPDLSCs suppressed the tube forming abilities of HUVECs.

CONCLUSIONS

CsA enhanced the osteogenic differentiation and reduced angiogenesis by blocking the ERK and p38/c-fos pathway in hPDLSCs. It is necessary to confirm whether this phenomenon is also observed in vivo in subsequent animal experiments.

Cardiomyocyte calcineurin is required for the onset and progression of cardiac hypertrophy and fibrosis in adult mice

Previous studies have demonstrated that activation of calcineurin induces pathological cardiac hypertrophy (CH). In these studies, loss-of-function was mostly achieved by systemic administration of the calcineurin inhibitor cyclosporin A. The lack of conditional knockout models for calcineurin function has impeded progress toward defining the role of this protein during the onset and the development of CH in adults. Here, we exploited a mouse model of CH based on the infusion of a hypertensive dose of angiotensin II (AngII) to model the role of calcineurin in CH in adulthood. AngII-induced CH in adult mice was reduced by treatment with cyclosporin A, without affecting the associated increase in blood pressure, and also by induction of calcineurin deletion in adult mouse cardiomyocytes, indicating that cardiomyocyte calcineurin is required for AngII-induced CH. Surprisingly, cardiac-specific deletion of calcineurin, but not treatment of mice with cyclosporin A, significantly reduced AngII-induced cardiac fibrosis and apoptosis. Analysis of profibrotic genes revealed that AngII-induced expression of Tgfβ family members and Lox was not inhibited by cyclosporin A but was markedly reduced by cardiac-specific calcineurin deletion. These results show that AngII induces a direct, calcineurin-dependent prohypertrophic effect in cardiomyocytes, as well as a systemic hypertensive effect that is independent of calcineurin activity.

Cell cycle shift from G0/G1 to S and G2/M phases is responsible for increased adhesion of calcium oxalate crystals on repairing renal tubular cells at injured site

Renal tubular cell injury can enhance calcium oxalate monohydrate (COM) crystal adhesion at the injured site and thus may increase the stone risk. Nevertheless, underlying mechanism of such enhancement remained unclear. In the present study, confluent MDCK renal tubular cell monolayers were scratched to allow cells to proliferate and repair the injured site. At 12-h post-scratch, the repairing cells had significant increases in crystal adhesion capacity and cell proliferation as compared to the control. Cell cycle analysis using flow cytometry demonstrated that the repairing cells underwent cell cycle shift from G0/G1 to S and G2/M phases. Cyclosporin A (CsA) and hydroxyurea (HU) at sub-toxic doses caused cell cycle shift mimicking that observed in the repairing cells. Crystal-cell adhesion assay confirmed the increased crystal adhesion capacity of the CsA-treated and HU-treated cells similar to that of the repairing cells. These findings provide evidence indicating that cell cycle shift from G0/G1 to S and G2/M phases is responsible, at least in part, for the increased adhesion of COM crystals on repairing renal tubular cells at the injured site.

Down-regulation of miR-200b-targeting Slug axis by cyclosporine A in human gingival fibroblasts

BACKGROUND/PURPOSE

Cyclosporine A (CsA) has been used as an immunosuppressive agent with a side effect of gingival overgrowth. It has been known that CsA-induced epithelial-mesenchymal transition (EMT) in gingiva, but the molecular mechanism has not been fully unveiled. The purpose of the study is to investigate functional roles of microRNAs in gingival overgrowth.

METHODS

The effect of CsA on the expression of microRNA-200b (miR-200b) in normal human gingival fibroblasts (HGFs) was determined using qRT-PCR. Luciferase reporter assay and Western blot were utilized to examine the relationship between miR-200b and EMT inducer Slug. Cell proliferation was assessed by MTT assay.

RESULTS

CsA was found to downregulate the miR-200b transcript in HGFs in a dose-dependent manner. Luciferase reporter assay confirmed that Slug was a direct target of miR-200b, and the CsA-induced cell proliferation and Slug upregulation were inhibited by overexpression of miR-200b. Additionally, the silence of Slug reversed the increased proliferation of HGFs by miR-200b inhibitor.

CONCLUSION

Repression of miR-200b after CsA administration led to an increase in Slug expression. Our results suggested that miR-200b was an upstream effector of the CsA-induced EMT and may act as a therapeutic target for CsA-induced gingival overgrowth.

Effects of cyclosporin, nifedipine and phenytoin on gingival myofibroblast transdifferentiation in monkeys

OBJECTIVE

Myofibroblasts have been associated with the development of several pathologic fibrotic conditions. This longitudinal study aims to assess the proliferative and antiapoptotic effects of cyclosporin, nifedipine and phenytoin on gingival connective tissue cells of nonhuman primate, as well as to analyze a possible role of myofibroblasts in gingival overgrowth.

MATERIALS AND METHODS

Gingival samples from the right superior canine area were obtained from 12 male monkeys ( Sapajus spp ) to comprise the control group. After one week, the animals were randomly assigned to three groups, which received daily oral doses of cyclosporin, nifedipine or phenytoin for 120 days. Gingival samples were collected from the left superior canine area of two animals of each group at 52 and 120 days. Histological sections were stained with hematoxylin and eosin, and immunoreacted against α-SMA, Ki- 67 and bcl-2.

RESULTS

α-SMA immunoreaction was negative in the control and experimental groups. Similarly, no difference between groups concerning immunostaining against Ki-67 and bcl-2 was observed in connective tissue cells.

CONCLUSION

Based on this methodology, it may be concluded that gingival overgrowths induced by cyclosporin, nifedipine and phenytoin are not associated with neither myofibroblast transdifferentiation, proliferation nor apoptosis of gingival connective cells in monkeys.

Mitochondria and Calcium Regulation as Basis of Neurodegeneration Associated With Aging

Age is the main risk factor for the onset of neurodegenerative diseases. A decline of mitochondrial function has been observed in several age-dependent neurodegenerative diseases and may be a major contributing factor in their progression. Recent findings have shown that mitochondrial fitness is tightly regulated by Ca²⁺ signals, which are altered long before the onset of measurable histopathology hallmarks or cognitive deficits in several neurodegenerative diseases including Alzheimer’s disease (AD), the most frequent cause of dementia. The transfer of Ca²⁺ from the endoplasmic reticulum (ER) to the mitochondria, facilitated by the presence of mitochondria-associated membranes (MAMs), is essential for several physiological mitochondrial functions such as respiration. Ca²⁺ transfer to mitochondria must be finely regulated because excess Ca²⁺ will disturb oxidative phosphorylation (OXPHOS), thereby increasing the generation of reactive oxygen species (ROS) that leads to cellular damage observed in both aging and neurodegenerative diseases. In addition, excess Ca²⁺ and ROS trigger the opening of the mitochondrial transition pore mPTP, leading to loss of mitochondrial function and cell death. mPTP opening probably increases with age and its activity has been associated with several neurodegenerative diseases. As Ca²⁺ seems to be the initiator of the mitochondrial failure that contributes to the synaptic deficit observed during aging and neurodegeneration, in this review, we aim to look at current evidence for mitochondrial dysfunction caused by Ca²⁺ miscommunication in neuronal models of neurodegenerative disorders related to aging, with special emphasis on AD.

Epithelial to mesenchymal transition in Cyclosporine A-induced rat gingival overgrowth

BACKGROUND AND OBJECTIVE

Epithelial-mesenchymal transition (EMT) has been proved to occur in drug-induced gingival overgrowth. However, the specific pathogenic mechanism remains uncertain. The aim of this study is to examine the expression of EMT markers in cyclosporine A (CsA)-induced gingival overgrowth in rat models.

MATERIAL AND METHODS

Thirty-six rats were randomly divided into two groups. The experimental group received CsA therapy subcutaneously in a daily dose of 10mg/kg, and the other group was used as a control. Six rats per group were sacrificed at 20, 40 and 60days, and the gingivae were obtained. The expression of TGF-β1, E-Cadherin, ZEB1, ZEB2, and Snail1 were examined by quantitative real time PCR (qRT-PCR), western blotting, and immunohistochemistry. In addition, a group of microRNAs associated with EMT and fibrosis were also detected in gingival tissue by qRT-PCR.

RESULTS

The mRNA and protein levels of TGF-β1, ZEB1, and ZEB2 in gingivae were significantly upregulated after 40 and 60days of CsA administration. Conversely, the levels of E-cadherin were significantly downregulated in overgrowth sample at day 40 and 60. Intense immunohistochemmical staining for TGF-β1 were observed in the samples from CsA group at day 40 and 60. Concomitantly, the densities of E-cadherin were gradually decreased in the basal layers of epithelium with time. Three members of miR-200s (miR-200a, miR-200b and miR-200c) were significantly downregulated in CsA-treated rats at 40 and 60days, while miR-9, miR-23a and miR-155 were significantly upregulated when compared with those of the control group.

CONCLUSIONS

The process of EMT in CsA-induced rat gingival overgrowth is associated with increased expression of TGF-β1, ZEB1, and ZEB2, and decreased expression of E-cadherin.