Expression Profiles of Inflammation-associated microRNAs in Periapical Lesions and Human Periodontal Ligament Fibroblasts Inflammation

B Cells at the Core: Immune Mechanisms and Therapeutic Potentials in Periapical Lesions

INTRODUCTION

Periapical lesions (PLs) are common inflammatory diseases primarily caused by microbial infections within root canals. These infections trigger complex immune responses in periapical tissues, with B lymphocytes playing dual roles: defending against pathogens while also contributing to tissue damage. This highlights the crucial role of B cells in the immunological processes of PLs.

METHOD

A comprehensive review of the literature on B cells in PLs was conducted using PubMed, Web of Science, Scopus, and ScienceDirect databases.

RESULTS

The review included 123 studies that examined the distribution and subtypes of B cells, their dual functions in PLs, and the potential applications of B-cell-related therapies in treating apical periodontitis.

CONCLUSION

This review enhances our understanding of the complex immune mechanisms in PLs and aids in the development of new therapeutic approaches from a B-cell perspective.

Milk-derived small extracellular vesicles inhibit the MAPK signaling pathway through CD36 in chronic apical periodontitis

BACKGROUND

Small extracellular vesicles derived from milk (Milk-sEVs) have the advantages of easy availability, low cost, low toxicity, and inhibition of inflammation. CD36 mediates inflammation stress in a variety of disease states. The purpose of this study was to investigate the role of Milk-sEVs in inhibiting fibroblast inflammation through CD36 and provide reference data for the treatment of chronic apical periodontitis.

RESULTS

The addition of Milk-sEVs resulted in decreased expression of inflammation-related factors in L929 cells, and transcriptome sequencing screened for the DEG CD36 in the Milk-sEV treatment group under inflammation. The mouse model of apical periodontitis was successfully established, and CD36 expression increased with the development of inflammation. Transfection of si-CD36 into L929 cells reduced inflammation by inhibiting activation of the MAPK signaling pathway.

CONCLUSIONS

CD36 expression increased with the development of apical periodontitis. In the setting of LPS-mediated inflammation, Milk-sEVs inhibited activation of the MAPK signaling pathway by decreasing the expression of CD36 in L929 cells and thereby reducing inflammation.

The Evaluation of a 5-miRNA Panel in Patients with Periodontitis Disease

INTRODUCTION

Side by side with tooth decay, periodontitis remains one of the most common oral diseases and is increasingly recognized as a serious public health concern worldwide.

OBJECTIVES

The present study aims at comparing the levels of 5 specific miRNAs (miR-29b-3p, miR-34a-5p, miR-155-5p, miR-181a-5p, and miR-192-5p) in patients with periodontal disease and healthy controls.

METHODS

The pathogenic mechanism is related to the activation of immune response and significant alteration of coding and noncoding genes, including miRNA. The study includes 50 subjects (17 with periodontal disease and 33 healthy controls) with a mean age of 45.3 y. In both periodontitis patients and healthy controls, a panel of 5 miRNAs (miR-29b-3p, miR-34a-5p, miR-155-5p, miR-181a-5p, and miR-192-5p) is examined by determining their expression levels with quantitative reverse transcription polymerase chain reaction.

RESULTS

The periodontitis patients express high levels of all the investigated miRNAs. Receiver operating characteristic curve analysis shows an area under the curve (AUC) of 0.69 to 0.74 for individual transcripts with the highest AUC value observed for miR-192, followed by miR-181a.

CONCLUSIONS

The study indicates that the 5-miRNA panel can be used as biomarker for periodontitis. In this way, all implantology procedures and treatment options for patients diagnosed with periodontitis can be improved for better long-term results, predictability, and follow-up frequency.

KNOWLEDGE TRANSFER STATEMENT

The discovery of a miRNA panel as a potential biomarker for periodontitis offers major opportunities for practical application. Our study can improve diagnostic accuracy; researchers can develop new theories on molecular mechanisms and biomarker discovery.

The role of Semaphorin 3A in oral diseases

Semaphorin 3A (SEMA3A), also referred to as H-Sema III, is a molecule with significant biological importance in regulating physiological and pathological processes. However, its role in oral diseases, particularly its association with inflammatory immunity and alveolar bone remodeling defects, remains poorly understood. This comprehensive review article aims to elucidate the recent advances in understanding SEMA3A in the oral system, encompassing nerve formation, periodontitis, pulpitis, apical periodontitis, and oral squamous cell carcinoma. Notably, we explore its novel function in inflammatory immunomodulation and alveolar bone formation during oral infectious diseases. By doing so, this review enhances our comprehension of SEMA3A's role in oral biology and opens up possibilities for modulatory approaches and potential treatments in oral diseases.

Oral Spirochete Treponema denticola Intraoral Infection Reveals Unique miR-133a, miR-486, miR-126-3p, miR-126-5p miRNA Expression Kinetics during Periodontitis

miRNAs are major regulators of eukaryotic gene expression and host immunity, and play an important role in the inflammation-mediated pathways in periodontal disease (PD) pathogenesis. Expanding our previous observation with the global miRNA profiling using partial human mouth microbes, and lack of in vivo studies involving oral spirochete Treponema denticola-induced miRNAs, this study was designed to delineate the global miRNA expression kinetics during progression of periodontitis in mice infected with T. denticola by using NanoString nCounter® miRNA panels. All of the T. denticola-infected male and female mice at 8 and 16 weeks demonstrated bacterial colonization (100%) on the gingival surface, and an increase in alveolar bone resorption (p < 0.0001). A total of 70 miRNAs with at least 1.0-fold differential expression/regulation (DE) (26 upregulated and 44 downregulated) were identified. nCounter miRNA expression profiling identified 13 upregulated miRNAs (e.g., miR-133a, miR-378) and 25 downregulated miRNAs (e.g., miR-375, miR-34b-5p) in T. denticola-infected mouse mandibles during 8 weeks of infection, whereas 13 upregulated miRNAs (e.g., miR-486, miR-126-5p) and 19 downregulated miRNAs (miR-2135, miR-142-3p) were observed during 16 weeks of infection. One miRNA (miR-126-5p) showed significant difference between 8 and 16 weeks of infection. Interestingly, miR-126-5p has been presented as a potential biomarker in patients with periodontitis and coronary artery disease. Among the upregulated miRNAs, miR-486, miR-126-3p, miR-126-5p, miR-378a-3p, miR-22-3p, miR-151a-3p, miR-423-5p, and miR-221 were reported in human gingival plaques and saliva samples from periodontitis and with diabetes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed various functional pathways of DE miRNAs, such as bacterial invasion of epithelial cells, Ras signaling, Fc gamma R-mediated phagocytosis, osteoclast differentiation, adherens signaling, and ubiquitin mediated proteolysis. This is the first study of DE miRNAs in mouse mandibles at different time-points of T. denticola infection; the combination of three specific miRNAs, miR-486, miR-126-3p, and miR-126-5p, may serve as an invasive biomarker of T. denticola in PD. These miRNAs may have a significant role in PD pathogenesis, and this research establishes a link between miRNA, periodontitis, and systemic diseases.

MicroRNAs and Periodontal Disease: Helpful Therapeutic Targets?

Periodontal disease is the most common oral disease. This disease can be considered as an inflammatory disease. The immune response to bacteria accumulated in the gum line plays a key role in the pathogenesis of periodontal disease. In addition to immune cells, periodontal ligament cells and gingival epithelial cells are also involved in the pathogenesis of this disease. miRNAs which are small RNA molecules with around 22 nucleotides have a considerable relationship with the immune system affecting a wide range of immunological events. These small molecules are also in relation with periodontium tissues especially periodontal ligament cells. Extensive studies have been performed in recent years on the role of miRNAs in the pathogenesis of periodontal disease. In this review paper, we have reviewed the results of these studies and discussed the role of miRNAs in the immunopathogenesis of periodontal disease comprehensively. miRNAs play an important role in the pathogenesis of periodontal disease and maybe helpful therapeutic targets for the treatment of periodontal disease.

Interleukin 6 and Interleukin 1β hypomethylation and overexpression are common features of apical periodontitis: a case-control study with gingival tissue as control

OBJECTIVES

Apical periodontitis is a periradicular tissue disorder that usually arises from infection by microorganisms in the root canal system resulting in local bone resorption. This usually involves the dysregulation of inflammatory mediators, which can be mediated by epigenetic mechanisms. Thus, the objective of this study was to evaluate Interleukin 6 (IL6) and Interleukin 1β (IL1β) and DNA methylation and gene expression levels in apical periodontitis.

METHODS

Gene expression was analyzed in 60 participants using quantitative polymerase chain reaction, while the methylation levels of IL6 and IL1β promoters were analyzed in 72 patients using pyrosequencing. All statistical analyzes were performed using the GraphPad Prism software version 8.0. The p value was considered statistically significant when < 0.05.

RESULTS

A significantly higher IL6 and IL1β expression levels were observed in cases relative to controls (fold-changes of 27.4 and 11.43, respectively, and p < 0.0001). By comparing the same groups, lower promoter methylation levels were observed for both genes in cases (methylation percentage delta relative to controls of -24.57% and -16.02%, respectively, and p < 0.0001). A significant inverse correlation between gene expression and promoter methylation was observed for both IL6 (p = 0.0002) and IL1β (p = 0.001). Neither IL6 expression nor promoter methylation were significantly associated with cases' age, smoking history, alcohol consumption history or sex. For IL1β, alcoholic cases showed lower methylation level relative to non-alcoholic cases (p = 0.01), while females showed higher methylation levels relative to males (p = 0.03).

CONCLUSIONS

Our data suggest a role for DNA methylation in IL6 and IL1β upregulation in apical periodontitis.

MicroRNAs Markedly Expressed in Apical Periodontitis Cooperatively Regulate Cytokines and Growth Factors Promoting an Anti-inflammatory Response

INTRODUCTION

MicroRNAs have been shown to play a role in the pathogenesis of apical periodontitis. Upregulation of miR-10a-5p and downregulation of miR-891a-5p were previously reported in apical periodontitis samples. This study aims to perform a functional characterization of miR-10a-5p, investigating its capacity to regulate the expression of inflammatory cytokines and growth factors, as well as a possible co-regulation mechanism with miR-891a-5p in the development of apical periodontitis.

METHODS

miR-10a-5p mimics/controls and miR-891a-5p inhibitors/controls were introduced to human K-562 cells in the presence or absence of lipopolysaccharide. Total RNA was extracted from cell lysates, and target genes were examined via quantitative reverse transcription-polymerase chain reaction. Cell lysates were also subjected to proteomics analysis. Furthermore, mimics of miR-10a-5p and inhibitors of miR-891a-5p were co-transfected into K-562 cells. RNA sequencing and quantitative reverse transcription-polymerase chain reaction were carried out to examine their target genes.

RESULTS

Overexpression of miR-10a-5p led to downregulation of tumor necrosis factor-alpha and interleukin-1 beta mRNA and upregulation of transforming growth factor-beta 1 (TGFB1) mRNA expression, whereas interleukin 3 and TGF-β1 proteins were upregulated. Simultaneous overexpression of miR-10a-5p and inhibition of miR-891a-5p further increased TGFB1 mRNA transcript levels. RNA sequencing revealed that genes co-regulated by miR-10a-5p and miR-891a-5p may be involved in apical periodontitis-related pathways such as tumor necrosis factor, transient receptor potential, and vascular endothelial growth factor signaling pathways.

CONCLUSIONS

miR-10a-5p may modulate the expression of multiple inflammatory cytokines and growth factors such as tumor necrosis factor-alpha, IL-1β, interleukin 3, and TGF-β1. In addition, miR-10a-5p and miR-891a-5p cooperatively regulate TGFB1 gene expression, and the gene network of this co-regulation is integrated with many pathways in apical periodontitis.

MiR-199a-5P promotes osteogenic differentiation of human stem cells from apical papilla via targeting IFIT2 in apical periodontitis

Introduction

Periapical alveolar bone loss is the common consequence of apical periodontitis (AP) caused by persistent local inflammation around the apical area. Human stem cells from apical papilla (hSCAPs) play a crucial role in the restoration of bone lesions during AP. Studies have recently identified the critical role of microRNAs (miRNAs) involved in AP pathogenesis, but little is known about their function and potential molecular mechanism, especially in the osteogenesis of hSCAPs during AP. Here, we investigated the role of clinical sample-based specific miRNAs in the osteogenesis of hSCAPs.

Methods

Differential expression of miRNAs were detected in the periapical tissues of normal and patients with AP via transcriptomic analysis, and the expression of miR-199a-5p was confirmed by qRT-PCR. Treatment of hSCAPs with miR-199a-5p mimics while loaded onto beta-tricalcium phosphate (β-TCP) ceramic particle scaffold to explore its effect on osteogenesis in vivo. RNA binding protein immunoprecipitation (RIP) and Luciferase reporter assay were conducted to identify the target gene of miR-199a-5p.

Results

The expression of miR-199a-5p was decreased in the periapical tissues of AP patients, and miR-199a-5p mimics markedly enhanced cell proliferation and osteogenic differentiation of hSCAPs, while miR-199a-5p antagomir dramatically attenuated hSCAPs osteogenesis. Moreover, we identified and confirmed Interferon Induced Protein with Tetratricopeptide Repeats 2 (IFIT2) as a specific target of miR-199a-5p, and silencing endogenous IFIT2 expression alleviated the inhibitory effect of miR-199a-5p antagomir on the osteogenic differentiation of hSCAPs. Furthermore, miR-199a-5p mimics transfected hSCAPs loaded onto beta-tricalcium phosphate (β-TCP) scaffolds induced robust subcutaneous ectopic bone formation in vivo.

Discussion

These results strengthen our understanding of predictors and facilitators of the key AP miRNAs (miR-199a-5p) in bone lesion repair under periapical inflammatory conditions. And the regulatory networks will be instrumental in exploring the underlying mechanisms of AP and lay the foundation for future regenerative medicine based on dental mesenchymal stem cells.

MicroRNA expression in apical periodontitis and pulpal inflammation: a systematic review

Background

The aim of this systematic review is to determine microRNAs (miRs) that are differently expressed between diseased pulpal and periapical tissues.

Design

This systematic review used PubMed, Scopus, EBSCO, ProQuest, Cochrane database as well as manual searching to extract studies from January 2012 up to February 2022.

Results

A total of 12 studies met the eligibility criteria were included. All selected studies were of case-control type. Twenty-four miRNAs associated with apical periodontitis, 11 were found to be upregulatedand 13 were downregulated. Four out of the 44 miRs associated with pulpal inflammation were upregulated, whereas forty were downregulated. Six miRs, namely hsa-miR-181b, hsa-miR-181c,hsa-miR-455-3p,hsa-miR-128-3p, hsa-miR199a-5p, and hsa-miR-95, exhibited considerable downregulation in both periapical and pulp tissues.

Conclusion

MiRs have been investigated for their role in pulpal and periapical biology and may be utilised in diagnostic and therapeutic purposes. Further investigations are required to determine why certain irreversible pulpitis situations progress to apical periodontitis and others do not, based on the various miR expressions. Moreover, clinical and laboratory trials are needed to support this theory.

Inhibition of RGS10 Aggravates Periapical Periodontitis via Upregulation of the NF-κB Pathway

INTRODUCTION

Periapical periodontitis develops due to the interplay between root canal microorganisms and host defenses. The mechanism underlying the pathogenesis of periapical periodontitis remains unclear. Regulator of G protein signaling protein 10 (RGS10) has been suggested to play a role in regulating inflammation. This study explored the potential regulatory effects of RGS10 on periapical periodontitis and the pro-inflammatory pathway of NF-κB.

METHODS

Disease models of periapical inflammation in mice were established, and adenovirus-associated virus (AAV) was used to inhibit RGS10 expression. Periapical lesions were detected using microcomputed tomography. Quantitative real-time PCR (qRT-PCR), western blotting (WB), enzyme-linked immunosorbent assay (ELISA), enzyme activity staining of tartrate-resistant acid phosphatase, and immunohistochemistry were conducted to assess the role of RGS10 expression on NF-κB pro-inflammatory signaling, OPG, RANKL, and osteoclasts in the periapical regions of each group. TNFα was used to stimulate L929 cells alone or with small interfering RNA (siRNA). To assess the expression of associated molecules, WB, immunofluorescence, qRT-PCR, and ELISA were performed.

RESULTS

RGS10 inhibition increased alveolar bone destruction in periapical periodontitis lesions and substantially enhanced the NF-κB pro-inflammatory signaling pathway activation level. Furthermore, RGS10 inhibition upregulated the ratio of OPG/RANKL and the maturation of osteoclasts during alveolar bone resorption. L929 cell TNFα stimulation and siRNA transfection confirmed these in vivo results.

CONCLUSION

RGS10 negatively regulates NF-κB pro-inflammatory signaling in periapical periodontitis and participates in bone remodeling. Therefore, RGS10 is a promising treatment option for long-term chronic periapical inflammation and may be a new target for the artificial regulation of inflammation.

Semaphorin 3A protects against alveolar bone loss during orthodontic tooth movement in mice with periodontitis

OBJECTIVE

This study investigated the effect of local semaphorin 3A (Sema3A) administration on alveolar bone loss during OTM in a mouse model of periodontitis.

BACKGROUND

Orthodontic tooth movement (OTM) for patients with periodontal disease is known to increase the risk of exacerbating alveolar bone loss due to inflammation of the periodontal tissue. However, its mechanism of action and prevention remains unclear.

METHODS

Mice (male 7-8 weeks old, C57BL/6J, n = 12) were divided into six groups: untreated group (control), without OTM and recovered from induced periodontitis (RP), with OTM and administered PBS or Sema3A to the gingiva after induced periodontitis (VehPO, SemaPO), with OTM and administered PBS or Sema3A to the gingiva without periodontitis induction (VehNO, SemaNO). Samples were collected on 14 days, and bone loss, histological analysis, cytokine production level, and tooth movement were assessed. Cultured human periodontal ligament (hPDL) cells were stimulated with lipopolysaccharide (LPS) and compressive force (CF), and mRNA expression levels of Sema3A and its receptors were analyzed.

RESULTS

The bone loss was significantly lower in the SemaPO group than in the VehPO group. The number of TRAP-positive cells in the SemaPO group was significantly lower than that in the VehPO group and was at the same level as that in the control group. The receptor activator of nuclear factor (NF)-kB-ligand/osteoprotegerin (RANKL/OPG) ratio and the levels of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, IL-17, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, in the gingival tissues were significantly lower in the SemaPO group than in the VehPO group. Additionally, Sema3A mRNA expression in hPDL cells was significantly decreased by co-stimulation with LPS and CF compared with that in the control group. Finally, the distance moved (dist.) and the mesial tipping angle (θ) was significantly smaller in the SemaPO group than in the VehPO group and was not significantly different from that of VehNO.

CONCLUSION

Pathological alveolar bone loss exacerbated by OTM in periodontitis might be prevented by local administration of Sema3A without inhibiting OTM.

Mechanisms of bone remodeling and therapeutic strategies in chronic apical periodontitis

Chronic periapical periodontitis (CAP) is a typical oral disease in which periodontal inflammation caused by an odontogenic infection eventually leads to bone loss. Uncontrolled infections often lead to extensive bone loss around the root tip, which ultimately leads to tooth loss. The main clinical issue in the treatment of periapical periodontitis is the repair of jawbone defects, and infection control is the first priority. However, the oral cavity is an open environment, and the distribution of microorganisms through the mouth in jawbone defects is inevitable. The subversion of host cell metabolism by oral microorganisms initiates disease. The presence of microorganisms stimulates a series of immune responses, which in turn stimulates bone healing. Given the above background, we intended to examine the paradoxes and connections between microorganisms and jaw defect repair in anticipation of new ideas for jaw defect repair. To this end, we reviewed the microbial factors, human signaling pathways, immune cells, and cytokines involved in the development of CAP, as well as concentrated growth factor (CGF) and stem cells in bone defect repair, with the aim of understanding the impact of microbial factors on host cell metabolism to inform the etiology and clinical management of CAP.

MicroRNA-155 expression is associated with pulpitis progression by targeting SHIP1

BACKGROUND

Pulpitis is a commonly seen oral inflammation condition in clinical practice, it can cause much pain for the patient and may induce infections in other systems. Much is still unknown for the pathogenic mechanism of pulpitis. In this work, we discovered that the expression of miR-155 was associated with dental pulpal inflammation both in vivo and in vitro.

METHODS AND RESULTS

Our experiments of LPS stimulated odontoblast cell line MDPC-23 showed miR-155 could act as a positive regulator by increasing the production of pro-inflammatory cytokines IL-1β and IL-6 during inflammatory responses, whereas knockdown of miR-155 can reverse the effects. Bioinformatics analysis demonstrated that SHIP1 is a direct target of miR-155 in odontoblasts, this result was further verified at both mRNA and protein level. Inhibition of miR-155 resulted in the downregulation of inflammation factors, while co-transfection of si-SHIP1 and miR-155 inhibitor promoted the inflammatory responses. Treatment with miR-155 mimic or si-SHIP1 up-regulated the protein level of p-PI3K and p-AKT. By contrast, miR-155 inhibitor exerted the opposite effects. miR-155 mimics could upregulate the gene expression of IL-1β and IL-6. Co-transfection of LY294002 and miR-155 mimic attenuated the inflammatory responses. Consistent with in vitro results, miR-155^-/- mice could alleviate inflammatory response, as well as decrease the activation of p-PI3K and p-AKT, whereas increase the activation of SHIP1.

CONCLUSIONS

Our data revealed a novel role for miR-155 in regulation of dental pulpal inflammatory response by targeting SHIP1 through PI3K/AKT signaling pathway.

Global Noncoding microRNA Profiling in Mice Infected with Partial Human Mouth Microbes (PAHMM) Using an Ecological Time-Sequential Polybacterial Periodontal Infection (ETSPPI) Model Reveals Sex-Specific Differential microRNA Expression

Periodontitis (PD) is a polymicrobial dysbiotic immuno-inflammatory disease. It is more prevalent in males and has poorly understood pathogenic molecular mechanisms. Our primary objective was to characterize alterations in sex-specific microRNA (miRNA, miR) after periodontal bacterial infection. Using partial human mouth microbes (PAHMM) (Streptococcus gordonii, Fusobacterium nucleatum, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia) in an ecological time-sequential polybacterial periodontal infection (ETSPPI) mouse model, we evaluated differential mandibular miRNA profiles by using high-throughput Nanostring nCounter® miRNA expression panels. All PAHMM mice showed bacterial colonization (100%) in the gingival surface, an increase in alveolar bone resorption (p < 0.0001), and the induction of a specific immunoglobin G antibody immune response (p < 0.001). Sex-specific differences in distal organ bacterial dissemination were observed in the heart (82% male vs. 28% female) and lungs (2% male vs. 68% female). Moreover, sex-specific differential expression (DE) of miRNA was identified in PAHMM mice. Out of 378 differentially expressed miRNAs, we identified seven miRNAs (miR-9, miR-148a, miR-669a, miR-199a-3p, miR-1274a, miR-377, and miR-690) in both sexes that may be implicated in the pathogenesis of periodontitis. A strong relationship was found between male-specific miR-377 upregulation and bacterial dissemination to the heart. This study demonstrates sex-specific differences in bacterial dissemination and in miRNA differential expression. A novel PAHMM mouse and ETSPPI model that replicates human pathobiology can be used to identify miRNA biomarkers in periodontitis.

Semaphorin 7A accelerates the inflammatory osteolysis of periapical lesions

INTRODUCTION

Semaphorin 7A (SEMA7A), the only member of the class VII semaphorin, has been considered as a potent immunomodulatory regulator, whose function in periapical lesions remains unclear. In our previous study, we found that SEMA7A was upregulated in human periapical periodontitis and might be involved in the immune response and tissue destruction of periapical lesions. In this research, we aimed to further explore the specifical regulatory role of SEMA7A as well as its regulatory mechanisms in the inflammatory progression of periapical lesions.

METHODS

Human periodontal ligament cells (hPDLCs) were collected from intact, caries-free, and healthy third molars and stimulated with recombinant human SEMA7A (rhSEMA7A). Real-time quantitative polymerase chain reaction (RT-qPCR), western blot and enzyme-linked immunosorbent assay (ELISA) were used to detect the mRNA and protein levels of inflammatory cytokines and matrix metalloproteinases (MMPs) in hPDLCs. 20 C57BL/6 mice were randomly divided into 4 groups: healthy control group, pulp exposure group, pulp exposure and saline treatment group and pulp exposure and rhSEMA7A treatment group. 20 μL sterile saline or 20 μL 200 ng/μL rhSEMA7A were injected respectively into the buccal mucosa around the root apex at day 0, 7, and 14. Mandibular tissues were collected at day 21. Micro-CT and immunohistochemical (IHC) staining were used to identify the bone destruction and inflammatory infiltration in periapical areas. Finally, AKT inhibitor (LY294002) was used to pretreat hPDLCs before rhSEMA7A stimulation to determine the role of AKT signaling activation in this process.

RESULTS

After treatment with rhSEMA7A, the mRNA and protein levels of interleukin (IL)-1β, IL-18, COX-2, MMP-1, and MMP-3 were remarkably upregulated in hPDLCs. In in vivo experiments, compared with other three groups, the treatment of rhSEMA7A would aggravate the osteolysis of alveolar bone and promote the infiltration of immune cells into the apex area accompanying with the increasing expression level of IL-1β, IL-18, matrix metalloproteinase (MMP)-1 and MMP-3. Furthermore, we found that the pro-inflammatory role of SEMA7A could be inhibited by the application of AKT inhibitor (LY294002).

CONCLUSION

SEMA7A likely aggravates the inflammatory reaction and bone destruction of existing periapical lesions. The pro-inflammatory role of SEMA7A in hPDLCs could partially be mediated through the ATK signaling transduction pathway.

NELL1 Augments Osteogenesis and Inhibits Inflammation of Human Periodontal Ligament Stem Cells Induced by BMP9

BACKGROUND

Periodontitis could lead to periodontal destruction such as the loss of alveolar bone. The issue that how to achieve the regeneration of alveolar bone and periodontal tissues under the inflammatory environment needs to be solved urgently. BMP9 is one of the most potent osteo-inductive BMPs and induces osteogenic differentiation of mesenchymal stem cells (MSCs). The aim of this study is to explore the possible effect of BMP9 on the osteogenic differentiation of inflammatory periodontal ligament stem cells (PDLSCs).

METHODS

Human PDLSCs were cultured in osteo-inductive medium with 1μg/mL lipopolysaccharide Porphyromonas gingivitis (LPS-PG). Adenoviral vector expressing system was used to overexpress target genes. In vitro expression of osteogenic markers was assessed by quantitative reverse transcription PCR, western blotting, alkaline phosphatase assay, and alizarin red staining. Subcutaneous implantation nude mice models were used to evaluate the effects of BMP9 on PDLSCs in vivo. Micro-CT, H&E staining, and trichrome staining were performed to assess ectopic bone formation.

RESULTS

In the LPS-PG induced inflammatory environment, BMP9 promoted osteogenic differentiation of PDLSCs, but upregulated the expression of inflammatory markers (P>0.05); NELL1 downregulated the expression of inflammation genes in PDLSCs induced by BMP9, while augmenting BMP9 induced osteogenesis of the cells both in vitro and in vivo. In the above process, the MAPK/p38/ERK signaling pathway was triggered by NELL1.

CONCLUSION

The combination use of BMP9 and NELL1 might have the potential to promote the regeneration of alveolar bone in periodontitis. This article is protected by copyright. All rights reserved.

Plasma Rich in Growth Factors in the Treatment of Endodontic Periapical Lesions in Adult Patients: A Narrative Review

Platelet concentrates have been widely used in regenerative medicine, including endodontics. The aim of this manuscript was to assess critically the efficacy of PRF in the treatment of endodontic periapical lesions in adult patients on the basis of the literature. The PICO approach was used to properly develop literature search strategies. The PubMed database was analyzed with the keywords: "((PRP) OR (PRF) OR (PRGF) OR (CGF)) AND (endodontic) AND ((treatment) OR (therapy))". After screening of 155 results, 14 articles were included in this review. Different types of platelet concentrates are able to stimulate the processes of proliferation and differentiation of mesenchymal stem cells. Platelet rich fibrin (PRF) releases growth factors for at least 7 days at the application site. Growth factors and released cytokines stimulate the activity of osteoblasts. Moreover, the release of growth factors accelerates tissue regeneration by increasing the migration of fibroblasts. It was not possible to assess the efficacy of PRF supplementation in the treatment of endodontic periapical lesions in permanent, mature teeth with closed apexes, due to the lack of well-designed scientific research. Further studies are needed to analyze the effect of PRF on the healing processes in the periapical region.

Non-coding RNAs in endodontic disease

The immunocompetence and regeneration potential of the dental pulp and its surrounding apical tissues have been investigated extensively in the field of endodontics. While research on the role of non-coding RNAs in these tissues is still in its infancy, it is envisioned that improved understanding of the regulatory function of ncRNAs in pulpal and periapical immune response will help prevent or treat endodontic disease. Of particular importance is the role of these RNAs in regenerating the dentin-pulp complex. In this review, we highlight recent progress on the role of non-coding RNAs in the immune response to endodontic infection as well as the repair and regenerative response to injury.

MicroRNAs: emerging players in apical periodontitis

Apical periodontitis is an inflammatory disorder of periradicular tissues developed from endodontic infections. Understanding its pathophysiology and the underlying molecular mechanisms is key to the advancement of endodontics. MicroRNAs (miRNAs), a group of evolutionarily conserved small non-coding RNAs, may be phenotypically and functionally associated with the pathogenesis of apical periodontitis. Several studies have focused on the role of miRNAs in the pulp and periradicular biology, and they have demonstrated their essential functions, such as initiating odontogenic differentiation and promoting pro- or anti-inflammatory responses in pulpitis. Up to date, over 2,000 miRNAs have been discovered in humans; however, only few have been reported to associate with apical periodontitis. Therefore, identifying miRNAs involved in diseased apical tissues and conducting functional studies are important in expanding our current knowledge of pulp and periradicular biology and exploring novel therapeutic avenues. In this review, we revisit current models of apical periodontitis and miRNA biogenesis, analyze existing evidence of the involvement of miRNAs in diseased apical tissues, and discuss their diverse functions and potential values. Based on their sheer abundance, prolonged stability in biofluid, and relative ease of sampling, miRNAs may be a useful tool to be developed as diagnostic biomarkers for apical periodontitis. Furthermore, it can be used as therapeutic targets in conjunction with conventional endodontic therapies.

miR-140 inhibits osteogenic differentiation of human periodontal ligament fibroblasts through ras homolog gene family, member A -transcriptional co-activator with PDZ-binding motif pathway

Osteogenesis induced by mechanical stretch is the main factor affecting the orthodontic treatment. Due to the masticatory force transmitted by tooth, human periodontal ligament fibroblasts (hPDLFs) could enhance osteogenic differentiation, and remolding of periodontal. Therefore, in-depth study of hPDLFs osteogenic differentiation and its regulatory mechanism is helpful in the understanding of periodontal remolding promoted by orthodontic force. In the present study, 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide showed that miR-140 inhibited the viability of hPDLFs cells. Moreover, we provided evidence that miR-140 inhibited alkaline phosphatase (ALP) activity, Alizarin Red S (ARS) activity and the mRNA expression of osteogenesis associated genes, including ALP, runt-related transcription factor 2, collagen 1, and osteocalcin. Besides, double-luciferase reporter result demonstrated that Ras homolog gene family, member A (RhoA) was a downstream target gene of miR-140, and by inhibiting RhoA-transcriptional co-activator with PDZ-binding motif (TAZ) signaling pathway, miR-140 suppressed the osteogenesis differentiation of hPDLFs. Furthermore, overexpression of RhoA or TAZ promoted ALP activity, ARS activity and osteogenesis associated genes expression, which was inhibited by miR-140 mimics. Our findings not only provided a possible mechanism of hPDLFs osteogenic differentiation but also proposed the clinical application of miR-140 inhibitor to target RhoA-TAZ for orthodontic treatment.

Association of DNA sequence-independent genetic regulatory mechanisms with apical periodontitis: A scoping review

OBJECTIVE

Different studies in the last decade have proposed that gene expression alterations that are independent of the DNA sequence may also play an important role in periapical disease. The present study aimed to assess the available evidence supporting a relationship between these alterations and apical periodontitis through a scoping review.

DESIGN

Specific strategies were developed for different databases (MEDLINE via PubMed, Cochrane Library, Scopus, Web of Science, and Virtual Health Library) and a search performed by March 1st, 2019. The evidence sources were selected according to the eligibility criteria and underwent a critical appraisal of methodological quality.

RESULTS

The initial search retrieved 212 references, with eight eligible articles after the removal of replicates and application of exclusion criteria. Five studies identified altered DNA methylation on inflammatory response genes (FOXP3, CXCL3, FADD, MMP2, MMP9, IFNG, IL4, IL12) on AP patients. Three others identified the alterations on the expression of several microRNAs (miR-29b, 106b, 125b, 143, 146a, 155, 198) during AP. No evidence was identified regarding mechanisms of histone methylation, or of epigenetic heritability or stability.

CONCLUSIONS

There is available evidence for the involvement of different genetic regulatory mechanisms independent of changes in DNA sequence in the development or severity of apical periodontitis. However, due to methodological limitations, further research must be performed before novel therapies and diagnostic tools for AP may arise from these data.

Genetic and Epigenetic Characterization of Pulpal and Periapical Inflammation

Pulpal and periapical diseases affect a large segment of the population. The role of microbial infections and host effector molecules in these diseases is well established. However, the interaction between host genes and environmental factors in disease susceptibility and progression is less well understood. Studies of genetic polymorphisms in disease relevant genes have suggested that individual predisposition may contribute to susceptibility to pulpal and periapical diseases. Other studies have explored the contribution of epigenetic mechanisms to these diseases. Ongoing research expands the spectrum of non-coding RNAs in pulpal disease to include viral microRNAs as well. This review summarizes recent advances in the genetic and epigenetic characterization of pulpal and periapical disease, with special emphasis on recent data that address the pathogenesis of irreversible pulpal pathosis and apical periodontitis. Specifically, proinflammatory and anti-inflammatory gene expression and gene polymorphism, as well as recent data on DNA methylation and microRNAs are reviewed. Improved understanding of these mechanisms may aid in disease prevention as well as in improved treatment outcomes.

miRNA-335-5p relieves chondrocyte inflammation by activating autophagy in osteoarthritis

AIMS

Osteoarthritis (OA) is a chronic and degenerative joint disease prevalent in the elderly, which is characterized by hypertrophy and reactive hyperplasia of articular cartilage. Autophagy has been reported to inhibit inflammation and reduce chondrocyte apoptosis in OA. As the microRNA (miRNA)-335-5p has been linked to both inflammation and autophagy, this study aimed to investigate its potential role in regulating autophagy during the pathogenesis of OA.

MAIN METHODS

Quantitative real-time PCR (qRT-PCR) was used to detect miRNA-335-5p expression in normal and OA human chondrocytes. Following transfection of human OA chondrocytes with double-stranded miRNA-335-5p mimic/inhibitor, qRT-PCR, western blotting, and immunofluorescence were used to determine expression levels of the inflammatory mediators IL-1β, IL-6, and TNF-α, and the autophagic markers Beclin-1, autophagy-related protein 5 (ATG5), and ATG7. The autophagy inhibitor 3-methyladenine (3-MA) was used to link the anti-inflammatory effects of miRNA-335-5p to autophagy.

KEY FINDINGS

The expression of miRNA-335-5p was significantly lower in OA chondrocytes than in normal chondrocytes. Transfection of human OA chondrocytes with the miRNA-335-5p mimic led to a remarkable increase in viability, a significant increase in autophagy-related factors, and a reduction in inflammatory mediators. Importantly, treatment of miRNA-335-5p-overexpressing OA chondrocytes with the autophagy inhibitor 3-MA restored the expression of inflammatory mediators.

SIGNIFICANCE

We conclude that miRNA-335-5p can significantly alleviate inflammation in human OA chondrocytes by activating autophagy. Therefore, miRNA-335-5p has potential for future use in the clinical diagnosis and treatment of OA.

Inflammatory profile of chronic apical periodontitis: a literature review

Apical periodontitis caused by root canal infection is the most frequent pathological lesion in the jaws, mainly manifested as periapical granulomas and cysts. Understanding of the formation and progression of apical periodontitis as well as the identification of inflammatory biomarkers can help increase the knowledge of pathogenic mechanisms, improve the diagnosis and provide support for different therapeutic strategies. The objective of the present article is to review inflammatory biomarkers such as cytokines, chemokines, inflammatory cells, neuropeptides, RANK/RANKL/OPG system and other inflammatory markers and to relate these systems to the development and progression of pathological conditions related to apical periodontitis.

Jumonji domain-containing protein 3 regulates the early inflammatory response epigenetically in human periodontal ligament cells

OBJECTIVE

To investigate the role of the histone 3 lysine 27 trimethylation (H3K27me3) demethylase Jumonji domain-containing protein 3 (Jmjd3) in the epigenetic regulation of the inflammatory response in human periodontal ligament cells (HPDLs).

DESIGN

HPDLs were stimulated with lipopolysaccharide from E. coli. The expression of Jmjd3 in HPDLs was examined by quantitative real-time polymerase chain reaction (Q-PCR), Western Blot and immunofluorescent staining. Potential target genes were selected by silencing Jmjd3 and were confirmed by Chromatin Immunoprecipitation (ChIP).

RESULTS

Q-PCR, Western Blot and immunofluorescent staining revealed that the expression of Jmjd3 was increased in inflamed HPDLs. Knockdown of Jmjd3 led to the suppression of inflammation-induced up-regulation of interleukin-6 and interleukin-12. Moreover, ChIP assays demonstrated that Jmjd3 was recruited to the promoters of interleukin-6 and interleukin-12b and this recruitment was associated with decreased levels of trimethylated histone 3 lysine 27 (H3K27).

CONCLUSIONS

It was concluded that Jmjd3 regulated the activation of interleukin-6 and interleukin-12b in the early inflammatory response of HPDLs via demethylation of H3K27me3 at promoters. This molecular event may play an important role in the regulation of the inflammatory response in HPDLs.

MicroRNA-335-5p Plays Dual Roles in Periapical Lesions by Complex Regulation Pathways

INTRODUCTION

MicroRNA-335-5p has been reported to regulate osteogenic and chondrogenic differentiations of mesenchymal stem cells. The aim of this study was to explore the function and regulation mechanism of miR-335-5p in apical periodontitis (AP).

METHODS

Total RNAs were extracted from human periodontal ligament fibroblasts (HPDLFs), 10 AP tissues, and 6 healthy periodontal ligament tissues using lysis buffer. Gene expression was detected using real-time polymerase chain reaction. The Dual Luciferase Assay (Promega, Madison, WI) was used to test miR-335-5p directly targeted urokinase-type plasminogen activator receptor (uPAR) and the receptor activator of nuclear factor kappa-B ligand (RANKL). Western Blot was used to detect protein expressions of RANKL, uPAR, and the fragile X-related 1 gene (FXR1). The enzyme-linked immunosorbent assay was used to detect the secretions of interleukin 6, tumor necrosis factor alpha, and RANKL. Data were analyzed using the Student t test.

RESULTS

miR-335-5p acted as a positive mediator in HPDLF inflammation (P < .05). Two targets of miR-335-5p, uPAR and RANKL, were identified. Interestingly, uPAR was repressed by miR-335-5p at the basal level, but it can be relieved from miR-335-5p-mediated repression, which is called derepression, when HPDLFs were subjected to lipopolysaccharide stimulation. miR-335-5p promoted RANKL in HPDLFs regardless of whether or not it was under inflammatory conditions (P < .05). We proved FXR1 was responsible for the derepression of uPAR from miR-335-5p (P < .01). Both FXR1 and uPAR were positive mediators in HPDLF inflammation (P < .05). miR-335-5p, uPAR, RANKL, and FXR1 had the same expression profiles in HPDLF inflammation and AP tissues (P < .05).

CONCLUSIONS

Our data showed that miR-335-5p may play dual roles in AP, and it might be considered as a target for therapeutic potency in clinical applications.

MicroRNA-125a-5p alleviates the deleterious effects of ox-LDL on multiple functions of human brain microvessel endothelial cells

MicroRNA-125a-5p (miR-125a-5p) could participate in the pathogenesis of vascular diseases. In this study, we investigated the role of miR-125a-5p in oxidized low-density lipoprotein (ox-LDL)-induced functional changes in human brain microvessel endothelial cells (HBMEC). The reactive oxygen species (ROS) production, nitric oxide (NO) generation, senescence, apoptosis, and functions of HBMEC were analyzed. For mechanism study, the epidermal growth factor receptor (EGFR)/extracellular signal-regulated protein kinase (ERK)/p38 mitogen-activated protein kinase (p38 MAPK) pathway and phosphatidylinositol-3-kinase (PI3K)/serine/threonine kinase (Akt)/endothelial nitric oxide synthase (eNOS) pathway were analyzed. Results showed the following: 1) Expression of miR-125a-5p was reduced in ox-LDL-treated HBMEC. 2) Overexpression of miR-125a-5p protected HBMEC from ox-LDL-induced apoptosis, senescence, ROS production, and NO reduction. 3) Overexpression of miR-125a-5p increased HBMEC proliferation, migration, and tube formation, while decreasing HBMEC adhesion to leukocytes, as well as counteracting the effects of ox-LDL on those functions. 4) The levels of EGFR/ERK/p38 MAPK pathway, PI3K/Akt/eNOS pathway, cleaved caspase-3, and adherent molecular ICAM-1 and VCAM-1 were associated with the effects of ox-LDL on these HBMEC functions. In conclusion, miR-125a-5p could counteract the effects of ox-LDL on various HBMEC functions via regulating the EGFR/ERK/p38 MAPK and PI3K/Akt/eNOS pathways and cleaved caspase-3, ICAM-1, and VCAM-1 expression.