Differential expression of transcription factors NF-κB and STAT3 in periodontal ligament fibroblasts and gingiva of healthy and diseased individuals

Anti-Inflammatory Activity of No-Ozone Cold Plasma in Porphyromonas gingivalis Lipopolysaccharide-Induced Periodontitis Rats

Periodontitis is an inflammatory disease caused by Porphyromonas gingivalis (P. gingivalis) in the oral cavity. This periodontal disease causes damage to the periodontal ligament and alveolar bone and can cause tooth loss, but there is no definite treatment yet. In this study, we investigated the possibility of using no-ozone cold plasma to safely treat periodontitis in the oral cavity. First, human gingival fibroblasts (HGFs) were treated with P. gingivalis-derived lipopolysaccharide (PG-LPS) to induce an inflammatory response, and then the anti-inflammatory effect of NCP was examined, and a study was conducted to identify the mechanism of action. Additionally, the anti-inflammatory effect of NCP was verified in rats that developed an inflammatory response similar to periodontitis. When NCP was applied to PG-LPS-treated HGFs, the activities of inflammatory proteins and cytokines were effectively inhibited. It was confirmed that the process of denaturing the medium by charged particles of NCP is essential for the anti-inflammatory effect of NCP. Also, it was confirmed that repeated treatment of periodontitis rats with NCP effectively reduced the inflammatory cells and osteoclast activity. As a result, this study suggests that NCP can be directly helpful in the treatment of periodontitis in the future.

Cardamonin decreases inflammatory mediator expression in IL-1β-stimulated human periodontal ligament cells

BACKGROUND

Cardamonin is classified as a natural chalcone, and has been reported to possess various bioactive effects. However, there have been limited attempts to utilize cardamonin in the treatment of periodontitis. This study aimed to investigate whether cardamonin has anti-inflammatory effects on human periodontal ligament cells (HPDLCs), which are a component cell of periodontal tissue. Specifically, the study seeks to determine whether cardamonin affects the expression of inflammatory mediators, such as cytokines and adhesion molecules, induced by interleukin-1β (IL-1β) in HPDLCs, as well as the signaling pathways activated by IL-1β.

METHODS

Cytokine and chemokine levels in supernatants of HPDLCs were measured by ELISA. Western blot analysis was used to measure protein expression and signal transduction pathway activation in HPDLCs.

RESULTS

We found that IL-1β-induced CC chemokine ligand (CCL)2, CCL5, CCL20, CXC-chemokine ligand (CXCL)10, and interleukin (IL)-6 production and intercellular adhesion molecule (ICAM)-1 and cyclooxygenase (COX)-2 expression in HPDLCs were suppressed by cardamonin treatment. We also found that cardamonin suppressed IL-1β-activated nuclear factor (NF)-κB pathway, and the phosphorylation of signal transducer and activator of transcription (STAT)3. Furthermore, cardamonin treatment enhanced the expression of the antioxidant enzymes, heme oxygenase (HO)-1 and NAD(P)H dehydrogenase [quinone] 1 (NQO1), in HPDLCs.

CONCLUSION

In this study, we found that cardamonin could suppress the production of inflammatory mediators in HPDLCs as well as the activation of several signaling pathways induced by IL-1β treatment.

Increased STAT3 Activation in Periodontitis Drives Inflammatory Bone Loss

Periodontitis is one of the most prevalent human inflammatory diseases. It is characterized by periodontal tissue destruction, progressively driven by the host response. In this regard, cytokines associated with tissue destruction, such as interleukin (IL)-6 and IL-23, use a common signaling pathway mediated by STAT3. This transcription factor is also needed for IL-17A production, a key mediator in periodontitis pathogenesis. Although several studies have reported increased activation of STAT3 in experimental periodontitis, a detailed characterization of STAT3 activation in human gingival tissues and its involvement in alveolar bone loss has yet to be explored. Using a cross-sectional study design, we detected increased proportions of pSTAT3-positive cells during periodontitis compared with health, particularly in epithelial cells and T cells. Other cell types of hematopoietic and nonhematopoietic origin also display STAT3 activation in gingival tissues. We detected increased STAT3 phosphorylation and expression of STAT3-related genes during experimental periodontitis. Next, we evaluated the role of STAT3 in alveolar bone destruction using a mouse model of STAT3 loss of function (mut-Stat3 mice). Compared with controls, mut-Stat3 mice had reduced alveolar bone loss following ligature-induced periodontitis. We also evaluated pharmacologic inhibition of STAT3 in ligature-induced periodontitis. Like mut-Stat3 mice, mice treated with STAT3 small-molecule inhibitor had reduced bone loss compared with controls. Our results demonstrate that STAT3 activation is increased in epithelial and T cells during periodontitis and indicate a pathogenic role of STAT3 in inflammatory alveolar bone loss.

Applications of Plasma-Activated Water in Dentistry: A Review

The activation of water by non-thermal plasma creates a liquid with active constituents referred to as plasma-activated water (PAW). Due to its active constituents, PAW may play an important role in different fields, such as agriculture, the food industry and healthcare. Plasma liquid technology has received attention in recent years due to its versatility and good potential, mainly focused on different health care purposes. This interest has extended to dentistry, since the use of a plasma–liquid technology could bring clinical advantages, compared to direct application of non-thermal atmospheric pressure plasmas (NTAPPs). The aim of this paper is to discuss the applicability of PAW in different areas of dentistry, according to the published literature about NTAPPs and plasma–liquid technology. The direct and indirect application of NTAPPs are presented in the introduction. Posteriorly, the main reactors for generating PAW and its active constituents with a role in biomedical applications are specified, followed by a section that discusses, in detail, the use of PAW as a tool for different oral diseases.

Aggravating Effects of Psychological Stress on Ligature-Induced Periodontitis via the Involvement of Local Oxidative Damage and NF-κB Activation

Periodontitis is the leading cause of tooth loss in adults, and psychological factors play an important role in the development of periodontitis. To elucidate the adverse effects of psychological stress on the inflammatory process and redox status of periodontitis tissue, fifty male Sprague-Dawley rats were divided into the control, experimental periodontitis, psychological stress, experimental periodontitis plus psychological stress, and experimental periodontitis plus psychological stress plus fluoxetine groups. Chronic unpredictable mild stress (CUMS) was used to establish psychological stress, and silk ligature was used to induce experimental periodontitis. Four weeks later, stressed rats showed altered behaviour, serum hormone levels, and sucrose preference. More obvious alveolar bone loss and attachment loss and higher protein expressions of inflammatory cytokines were observed in the experimental periodontitis plus psychological stress group. The combination of CUMS and periodontitis had synergistic effects on increasing hypoxia-inducible factor-1α (HIF-1α) protein expression and reactive oxygen species (ROS) and malondialdehyde (MDA) contents and decreasing antioxidant enzyme activities compared with those in the stress or periodontitis groups. Moreover, psychological stress further increased p-IκBα and p-NF-κB p65 protein levels and decreased IκBα protein levels in periodontitis rats. Fluoxetine administration alleviated the adverse effects of psychological stress on the progression of periodontitis in rats. These results hint us that psychological stress could aggravate inflammation in periodontitis tissues, which may be partly due to local worsening of oxidative damage and further activation of the nuclear factor kappa-B (NF-κB) signalling pathway.

Integrative Analysis of Deregulated miRNAs Reveals Candidate Molecular Mechanisms Linking H. pylori Infected Peptic Ulcer Disease with Periodontitis

OBJECTIVE

Periodontitis is a highly prevalent oral infectious disease and has been increasingly associated with H. pylori infection, gastric inflammation, and gastric cancer but little is known about epigenetic machinery underlying this potentially bidirectional association. The present study is aimed at identifying key deregulated miRNA, their associated genes, signaling pathways, and compounds linking periodontitis with H. pylori-associated peptic ulcer disease.

METHODS

miRNA expression datasets for periodontitis-affected and H. pylori-associated peptic ulcer disease-affected tissues were sought from the GEO database. Differentially expressed miRNA (DEmiRNAs) were identified and the overlapping, shared-DEmiRNA between both datasets were determined. Shared-DEmiRNA-target networks construction and functional analyses were constructed using miRNet 2.0, including shared-DEmiRNA-gene, shared-DEmiRNA-transcription factor (TF), and shared-DEmiRNA-compound networks. Functional enrichment analysis for shared DEmiRNA-gene and shared DEmiRNA-TF networks was performed using the KEGG, Reactome, and Geno Ontology (GO) pathways.

RESULTS

11 shared-DEmiRNAs were identified, among which 9 showed similar expression patterns in both diseases, and 7 were overexpressed. miRNA hsa-hsa-mir-155-5p and hsa-mir-29a-3p were top miRNA nodes in both gene and TF networks. The topmost candidate miRNA-deregulated genes were PTEN, CCND1, MDM2, TNRC6A, and SCD while topmost deregulated TFs included STAT3, HIF1A, EZH2, CEBPA, and RUNX1. Curcumin, 5-fluorouracil, and the gallotanin 1,2,6-Tri-O-galloyl-beta-D-glucopyranose emerged as the most relevant linkage compound targets. Functional analyses revealed multiple cancer-associated pathways, PI3K pathways, kinase binding, and transcription factor binding among as enriched by the network-associated genes and TFs.

CONCLUSION

Integrative analysis of deregulated miRNAs revealed candidate molecular mechanisms comprising of top miRNA, their gene, and TF targets linking H. pylori-infected peptic ulcer disease with periodontitis and highlighted compounds targeting both diseases. These findings provide basis for directing future experimental research.

Angiopoietin-like protein 2 deficiency promotes periodontal inflammation and alveolar bone loss

BACKGROUND

Human periodontitis is a highly prevalent inflammatory disease that leads to connective tissue degradation, alveolar bone resorption, and tooth loss. Angiopoietin-like 2 (ANGPTL2) regulates chronic inflammation in various diseases and is functionally involved in maintaining tissue homeostasis and promoting tissue regeneration, but there is limited information about its function in periodontitis. Here we investigated the expression and explicit role of ANGPTL2 in periodontitis.

METHODS

Immunohistochemistry and quantitative real-time PCR (qRT-PCR) were used to detect the ANGPTL2 expression in periodontal tissues and periodontal ligament cells (PDLCs). A ligature-induced periodontitis model was generated in wild-type and ANGPTL2 knockout mice. qRT-PCR and enzyme-linked immunosorbent assay were used to assess the production of inflammatory cytokines and matrix metalloproteinases (MMPs) in cultured PDLCs. Western blot was performed to detect proteins in relevant signaling pathways.

RESULTS

Increased ANGPTL2 expression was observed in inflamed periodontal tissues and PDLCs. ANGPTL2 deficiency promoted alveolar bone loss with enhanced osteoclastogenesis and inflammatory reactions in ligature-induced periodontitis. Downregulation of ANGPTL2 remarkably enhanced expression levels of interleukin (IL)-6, IL-8, MMP1, and MMP13 in Porphyromonas gingivalis lipopolysaccharide-induced PDLCs, whereas ANGPTL2-overexpressing PDLCs showed opposite trends. ANGPTL2 downregulation activated STAT3 and nuclear factor-κB pathways and blocked Akt signaling under inflammatory environment. Treatment with a STAT3 inhibitor partially suppressed the inflammatory reaction of PDLCs mediated by ANGPTL2 knockdown.

CONCLUSIONS

Our study provides the first evidence of an anti-inflammatory effect of ANGPTL2 in murine periodontitis. The findings demonstrate the critical and protective role of ANGPTL2 in alveolar bone loss and periodontal inflammation.

Expression of deubiquitinases in human gingiva and cultured human gingival fibroblasts

Background

Although deubiquitinating enzymes (DUBs) such as CYLD, A20 and OTULIN are expressed in multiple tissues and thought to be linked with inflammatory diseases, their expression in periodontal tissues remains to be determined. This research was designed to assess the expression of CYLD, A20 and OTULIN in human gingiva, and to evaluate the regulation of these DUBs in human gingival fibroblasts (HGFs) upon different stimuli.

Methods

Immunohistochemistry assay was conducted to determine the expression of CYLD, A20 and OTULIN in human gingiva. Immunofluorescence assay was employed to observe the protein expression of CYLD, A20 and OTULIN in HGFs. RT-PCR and western blots were carried out to assess gene and protein expression changes of these DUBs in HGFs upon LPS or TNF-α.

Results

CYLD, A20 and OTULIN were found to be expressed in human gingiva and HGFs. The expression of CYLD, A20 and OTULIN was lower in the inflamed gingival tissue samples compared with the healthy gingival tissue samples. Further, the expression of CYLD, A20 and OTULIN in HGFs exhibited distinct regulation by different stimuli. TNF-α treatment markedly increased NF-κB activation in HGFs

Conclusions

Our findings suggest that CYLD, A20 and OTULIN might play a role in the progression of periodontitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01655-4.

The inhibitory effect of the deubiquitinase cylindromatosis (CYLD) on inflammatory responses in human gingival fibroblasts

OBJECTIVE

Experiments were performed to evaluate CYLD expression in human gingival tissue samples and to examine the effects of CYLD on inflammatory responses in lipopolysaccharide (LPS)- or TNF-α-stimulated human gingival fibroblasts (HGFs).

METHODS

Immunohistochemistry for CYLD and p65 expression was performed with healthy and inflamed gingival tissue samples. siRNA was used to knock down the expression of CYLD in HGFs. Upon LPS or TNF-α stimulation, NF-κB activation was detected in control and CYLD-knockdown HGFs. RT-PCR was applied to determine gene expression. Western blot analyses were employed to assess protein expression. Immunofluorescence staining was carried out to evaluate the nuclear translocation of p65.

RESULTS

Immunohistochemical staining showed the expression of CYLD in human gingival tissues. In addition, CYLD protein expression was reduced in inflamed gingival tissue samples compared with healthy tissue samples. CYLD knockdown greatly enhanced the mRNA expression of proinflammatory cytokines in LPS- or TNF-α-stimulated HGFs. Furthermore, knocking down CYLD expression increased LPS-stimulated NF-κB activation in HGFs. Unexpectedly, CYLD knockdown did not affect TNF-α-induced NF-κB activation.

CONCLUSIONS

Our results suggest that CYLD participates in periodontal inflammatory responses by negatively regulating LPS-induced NF-κB signalling.

Activation of the STAT1 Pathway Accelerates Periodontitis in Nos3-/- Mice

Early studies on the etiology and pathogenesis of hypertension have shown that it has a considerable association with inflammation and the immune response as well as periodontitis. Clinical studies have also shown that hypertension can promote the periodontal tissue destruction caused by periodontitis. However, the underlying mechanisms remain unclear. This study aimed to explore the possible mechanisms of how hypertension aggravates periodontitis. Treatment with or without the signal transducer and activator of transcription 1 (STAT1) inhibitor fludarabine was performed in an endothelial nitric oxide synthase gene knockout-related (Nos3^-/-) mouse model with the hypertension phenotype of periodontitis induced by bacteria. Micro-computed tomography, immunohistochemistry, Western blot, quantitative reverse transcription polymerase chain reaction, immunofluorescence, and ELISA were performed. We demonstrated that Nos3^-/--related hypertension increases bone resorption and periodontal destruction in periodontitis lesion areas, which can be inhibited by the STAT1 inhibitor. Experimental data also showed that Nos3^-/- significantly increased macrophage infiltration and proinflammatory cytokine expression in the periodontitis lesion area, which is dependent on the angiotensin II-induced STAT1 pathway. Inhibition of STAT1 in vivo can decrease the expression of proinflammatory cytokines and macrophage infiltration. Furthermore, data in this study showed that Nos3^-/--related hypertension further downregulated the STAT3 anti-inflammatory function and its downstream chemokine expression in a STAT1-dependent manner. By applying RAW 264.7 and L929 cell lines and monocytes isolated from Nos3^-/- mice, we confirmed that activation of the STAT1 pathway inhibits STAT3 and its downstream pathway and promotes inflammatory cytokine expression in vitro. Collectively, our current study demonstrated that STAT1 plays an indispensable role in the Nos3^-/--related hypertension with aggravation of periodontitis, suggesting that STAT1 may be a key target for the treatment of periodontitis with hypertension.

Between Innovation and Standardization, Is There Still a Room for Scientific Reports? The Rise of a Formatting Tradition in Periodontal Research

Everybody, regardless of their role, is aware that biomedical research is rapidly evolving, and the demand for reproducibility is increasing together with the amount of novel information. “Before reproducibility must come pre-producibility” “Checklists work to improve science”, just to quote some of the articles querying how to find a new bridge between ethics in science and the urgency for publishing. Looking for papers on anti-inflammatory compounds in periodontics, we came across a significant number of articles that could be considered a prototype of a consistent study format. The literature on the testing of active compounds on lipopolysaccharides- (LPS)-induced inflammation in gingival fibroblasts was searched to identify studies that followed a consistent format, to better understand their similarities and assess the appropriateness of their methods. Several studies were identified with a degree of similarity in their methods and formatting that was so high that it was possible to rule out that it was due to chance, and a format template common to these studies was outlined. Although this was most likely beyond the intentions of their authors, these studies may pose the basis for an in-vitro testing standard for anti-inflammatory compounds; however, the dangers of acritical uniformity are also apparent.