Upregulation of Slug expression by cyclosporine A contributes to the pathogenesis of gingival overgrowth

Er:YAG laser suppresses pro-inflammatory cytokines expression and inflammasome in human periodontal ligament fibroblasts with Porphyromonas gingivalis-lipopolysaccharide stimulation

Background/purpose

Periodontitis is an inflammatory condition of the tooth-supporting structures triggered by the host's immune response towards the bacterial deposits around the teeth. It is well acknowledged that pro-inflammatory interleukin (IL)-6, IL-8, MCP-1 as well as the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, are the key modulators in the activation of this response. Erbium-doped yttrium-aluminium-garnet (Er:YAG) laser, a solid-state crystal laser have been commonly used in the treatment of periodontal diseases. However, little is understood about the molecular mechanism of the Er:YAG laser, especially in targeting the host immune response brought on by periodontal pathogens. Hence, the current study focused on the protective effects of Er:YAG laser on periodontitis in-vitro in terms of pro-inflammatory cytokines, chemokines and NLRP3 inflammasome expressions.

Materials and methods

Human periodontal ligament fibroblast (PDLFs) were first stimulated with lipopolysaccharides (LPS) from P. gingivalis (Pg-LPS) to simulate periodontitis. Cells were then irradiated with Er:YAG laser of ascending energy densities (3.6-6.3 J/cm2), followed by cell proliferation and wound healing assay. Next, the effects of Er:YAG laser on the expressions of IL-6, IL-8, MCP-1, NLRP3, and cleaved GSDMD were examined.

Results

Pg-LPS was found to reduce cell's proliferation rate and wound healing ability in PDLFs and these were rescued by Er:YAG laser irradiation. In addition, LPS stimuli resulted in a marked upregulation in the secretion of IL-6, IL-8 and MCP-1 as well as the mRNA and protein expression of NLRP3 and cleaved-GSDMD protein whereas Er:YAG laser suppressed the elicited phenomena.

Conclusion

To our knowledge, this is the first study to look into the laser's implication on the NLRP3 inflammasome in periodontitis models. Our study reveals a crucial role of Er:YAG laser in ameliorating periodontitis in-vitro through the modulation of IL-6, IL-8, MCP-1 and the NLRP3 inflammasome and highlights that the control of the NLRP3 inflammasome may become a potential approach for periodontitis.

Er:YAG Laser Alleviates Inflammaging in Diabetes-Associated Periodontitis via Activation CTBP1-AS2/miR-155/SIRT1 Axis

Periodontitis is a significant health concern for individuals with diabetes mellitus (DM), characterized by inflammation and periodontium loss. Hyperglycaemia in DM exacerbates susceptibility to periodontitis by inducing inflammaging in the host immune system. The use of erbium-doped yttrium-aluminum-garnet laser (ErL) in periodontitis treatment has gained attention, but its impact on diabetic-associated periodontitis (DP) and underlying mechanisms remain unclear. In this study, we simulated DP by exposing human periodontal ligament fibroblasts (PDLFs) to advanced glycation end products (AGEs) and lipopolysaccharides from P. gingivalis (Pg-LPS). Subsequently, we evaluated the impact of ErL on the cells' wound healing and assessed their inflammaging markers. ErL treatment promoted wound healing and suppressed inflammaging activities, including cell senescence, IL-6 secretion, and p65 phosphorylation. Moreover, the laser-targeted cells were observed to have upregulated expression of CTBP1-AS2, which, when overexpressed, enhanced wound healing ability and repressed inflammaging. Moreover, bioinformatic analysis revealed that CTBP1-AS2 acted as a sponge for miR155 and upregulated SIRT1. In conclusion, ErL demonstrated the ability to improve wound healing and mitigate inflammaging in diabetic periodontal tissue through the CTBP1-AS2/miR-155/SIRT1 axis. Targeting this axis could represent a promising therapeutic approach for preventing periodontitis in individuals with DM.

Anti-inflammaging effects of vitamin D in human gingival fibroblasts with advanced glycation end product stimulation

Background/purpose

:Both periodontal disease and diabetes mellitus (DM) are long-term inflammatory disorders that are highly prevalent and have a significant health impact. Inflammaging, a state of pre-aging and hyperinflammatory state has been acknowledged for its role in DM patients to have heightened risk of periodontitis. Numerous evidences revealed that inflammaging contributed by cell senescence, acceleration of inflammation and oxidative stress participates in the destruction of periodontium in DM. Abilities of vitamin D in suppressing inflammation and oxidative stress have been revealed in a range of tissues, however in DM’s gingival cells, the effect remain undefined.

Materials and methods

: Under the stimulation of advanced glycation end-products (AGEs), we assessed the cell proliferation in human gingival fibroblast (HGF), IL-6 and IL-8 secretions, cellular senescence expression and generation of reactive oxygen species (ROS) with or without vitamin D intervention. Following that, we examined the expression of Nrf2 and HO-1 to see if vitamin D was able to modulate the anti-oxidant signaling. A knockdown experiment was then conducted to proof the participation of Nrf2 on the secretion of pro-inflammatory IL-6 and IL-8.

Results

: Following the treatment of vitamin D, AGEs-elicited IL-6 and IL-8 production and cell senescence were dose-dependently repressed. Moreover, vitamin D attenuated AGEs-induced ROS in a dose-dependent pattern. Results from qRT-PCR demonstrated vitamin D reversed the suppression of Nrf2 and HO-1 induced by AGEs. Our findings revealed that the anti-inflammatory and anti-oxidant effect in vitamin D was mediated via the upregulation of Nrf2 expression.

Conclusion

: These data showed that high levels of AGEs in the gingiva lead to inflammaging reflected by increased pro-inflammatory cytokines, cell senescence expression and oxidative stress. Vitamin D supplementation can reduce oxidative stress and inflammation via the upregulation of Nrf2 signaling and hence, may be a potential approach for treatment of diabetes-associated periodontitis.

Anti-Inflammatory and Antioxidant Properties of Carvacrol and Magnolol, in Periodontal Disease and Diabetes Mellitus

Periodontal disease and diabetes mellitus are two pathologies that are extremely widespread worldwide and share the feature of chronic inflammation. Carvacrol is a phenolic monoterpenoid, produced by a variety of herbs, the most well-known of which is Origanum vulgare. Magnolol is a traditional polyphenolic compound isolated from the stem bark of Magnolia officinalis, mainly used in Chinese medicine. The purpose of this paper is to review the therapeutic properties of these bioactive compounds, in the treatment of periodontitis and diabetes. Based on our search strategy we conducted a literature search in the PubMed and Google Scholar databases to identify studies. A total of one hundred eighty-four papers were included in the current review. The results show that carvacrol and magnolol have anti-inflammatory, antioxidant, antimicrobial, anti-osteoclastic, and anti-diabetic properties that benefit both pathologies. Knowledge of the multiple activities of carvacrol and magnolol can assist with the development of new treatment strategies, and the design of clinical animal and human trials will maximize the potential benefits of these extracts in subjects suffering from periodontitis or diabetes.

Emerging Role of MicroRNA-200 Family in Dentistry

MicroRNAs (miRNAs) are endogenous non-coding RNAs ~22 nucleotides in length, which have been shown to participate in various biological processes. As one of the most researched miRNAs, the miR-200 family has been found to regulate several factors that are associated with the epithelial to mesenchymal transition (EMT) and cancer stem cells (CSCs) behavior. In this review, we briefly summarize the background of the miR-200 family and their implication in various dental diseases. We focus on the expression changes, biological functions, and clinical significance of the miR-200 family in oral cancer; periodontitis; oral potentially malignant disorder; gingival overgrowth; and other periodontal diseases. Additionally, we discuss the use of the miR-200 family as molecular biomarkers for diagnosis, prognostic, and therapeutic application.

The regulation of Oct4 in human gingival fibroblasts stimulated by cyclosporine A: Preliminary observations

Background/purpose

Oct4, a key transcription factor, could reprogram human somatic fibroblasts into embryonic stem cell-like pluripotent cells. The exact mechanism of cyclosporine A (CsA)-induced gingival overgrowth is still unclear. The aim of this study was to investigate the effects of CsA on the expression of Oct4 in cultured human gingival fibroblasts (HGFs) in vitro.

Materials and methods

The effects of CsA on HGFs were used to elucidate whether Oct4 expression could be induced by CsA by using quantitative real-time reverse transcription-polymerase chain reaction and western blot. Cell growth in CsA-treated HGFs with Oct4 lentiviral-mediated shRNAi knockdown was evaluated by tetrazolium bromide reduction assay.

Results

CsA was found to upregulate Oct4 transcript in a dose-dependent manner (p < 0.05). CsA also dose-dependently increased Oct4 protein expression (p < 0.05). The lentivirus expressing sh-Oct4 successfully prevented the CsA-induced Oct4 mRNA and protein in HGFs (p < 0.05). However, knockdown of Oct4 was insufficient to inhibit CsA-stimulated cell growth in HGFs. Furthermore, double knockdown with pluripotency-associated transcription factor Nanog showed that the down-regulation of Oct4/Nanog by lentiviral infection significantly inhibited CsA-stimulated cell growth (p < 0.05).

Conclusion

Taken together, CsA was first found to upregulate Oct4 mRNA and protein expression in HGFs. The silencing Oct4 could not suppress cell growth unless Nanog was repressed simultaneously.

miR-200a inhibits proliferation rate in drug-induced gingival overgrowth through targeting ZEB2

BACKGROUND/PURPOSE

Gingival overgrowth can occur as a result of poor oral hygiene or a side effect of taking certain medications, such as cyclosporine A (CsA). It has been shown that this immunosuppressant drug induces epithelial-to-mesenchymal transition (EMT) in the gingival epithelium but the associated molecular mechanism remains to be elucidated.

METHODS

We first assessed the relative expression of microRNA-200a (miR-200a) in response to the CsA treatment using qRT-PCR. Next, luciferase reporter assay was applied to examine whether miR-200a was able to regulate ZEB2 and Western blot was utilized to measure the expression of ZEB2 in normal human gingival fibroblasts (HGFs). To confirm the significance of miR-200a and ZEB2 in the CsA-induced gingival overgrowth, miR-200a inhibitor and shRNA mediated knockdown of ZEB2 were used and cell proliferation in HGFs was assessed by MTT assay.

RESULTS

The expression of miR-200a was dose-dependently downregulated following the CsA treatment. Luciferase reporter assay confirmed that ZEB2 was a direct downstream target regulated by miR-200a and ZEB2 was indeed increased after the administration of CsA. We demonstrated that knockdown of ZEB2 hampered the CsA-induced HGFs proliferation and the elevated cell proliferation due to inhibition of miR-200a was reversed by repression of ZEB2.

CONCLUSION

Our results showed that insufficient miR-200a in HGFs caused by CsA administration may lead to gingival enlargement mediated by the upregulation of ZEB2. This finding supported that CsA-induced EMT contributed to the adverse effect of using CsA and miR-200a may serve as an upstream target to prevent the overgrowth of the gingiva.

Negative feedback by SNAI2 regulates TGFβ1-induced amelotin gene transcription in epithelial-mesenchymal transition

Junctional epithelium (JE) demonstrates biological responses with the rapid turnover of gingival epithelial cells. The state occurs in inflammation of gingiva and wound healing after periodontal therapy. To understand the underlying mechanisms and to maintain homeostasis of JE, it is important to investigate roles of JE-specific genes. Amelotin (AMTN) is localized at JE and regulated by inflammatory cytokines and apoptotic factors that represent a critical role of AMTN in stabilizing the dentogingival attachment, which is an entrance of oral bacteria. In this study, we demonstrated that the AMTN gene expression was regulated by SNAI2 and transforming growth factor β1 (TGFβ1)-induced epithelial-mesenchymal transition (EMT) that occurs in wound healing and fibrosis during chronic inflammation. SNAI2 downregulated AMTN gene expression via SNAI2 bindings to E-boxes (E2 and E4) in the mouse AMTN gene promoter in EMT of gingival epithelial cells. Meanwhile, TGFβ1-induced AMTN gene expression was attenuated by SNAI2 and TGFβ1-induced SNAI2, without inhibition of the TGFβ1-Smad3 signaling pathway. Moreover, SNAI2 small interfering RNA (siRNA) rescued SNAI2-induced downregulation of AMTN gene expression, and TGFβ1-induced AMTN gene expression was potentiated by SNAI2 siRNA. Taken together, these data demonstrated that AMTN gene expression in the promotion of EMT was downregulated by SNAI2. The inhibitory effect of AMTN gene expression was an independent feedback on the TGFβ1-Smad3 signaling pathway, suggesting that the mechanism can be engaged in maintaining homeostasis of gingival epithelial cells at JE and the wound healing phase.

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.

Upregulation of embryonic stem cell marker Nanog in human gingival fibroblasts stimulated with cyclosporine A: An in vitro study

Background/purpose

Gingival overgrowth is a common side effect of medication with the immunosuppressant cyclosporine A (CsA). This study proposed to verify whether Nanog, an embryonic stem cell marker, contributes to gingival overgrowth stimulated with CsA in human gingival fibroblasts (HGFs).

Materials and methods

The effect of CsA on HGFs was used to elucidate whether Nanog expression could be induced by CsA using quantitative real-time reverse transcription-polymerase chain reaction and Western blotting. Cell growth in CsA-treated HGFs with Nanog lentivirus-mediated short hairpin RNA interference knockdown was evaluated by tetrazolium bromide reduction assay.

Results

CsA upregulated Nanog transcript in HGFs in a dose-dependent manner (P < 0.05). CsA was also shown to increase Nanog protein expression in HGFs in a dose-dependent manner (P < 0.05). In addition, downregulation of Nanog by lentiviral infection significantly inhibited CsA-stimulated cell growth in HGFs (P < 0.05).

Conclusion

CsA upregulated Nanog expression and cell growth in HGFs, while silencing Nanog effectively reversed these phenomena. Nanog may act as a major switch in the pathogenesis of CsA-induced gingival overgrowth.