The miR-155-5p inhibits osteoclast differentiation through targeting CXCR2 in orthodontic root resorption

HDAC9-Mediated Pyroptosis Promotes Orthodontically Induced Inflammatory Root Resorption

INTRODUCTION AND AIMS

Orthodontically induced inflammatory root resorption (OIIRR) is a common iatrogenic outcome of orthodontic treatment. Both epigenetic modifications and pyroptosis have demonstrated a certain role in OIIRR. This study aims to investigate whether epigenetic modifications regulate pyroptosis to be involved in OIIRR.

METHOD

Rat model of OIIRR was established, and the periodontal tissues were utilized for H&E staining, TRAP staining, immunofluorescence, transcriptome sequencing, and RT-qPCR analysis. Human periodontal ligament fibroblasts (hPDLFs) were overexpressed with HDAC9, treated with pyroptosis inhibitor, incubated with osteoclast, and then subjected to CUT&Tag sequencing.

RESULTS

Orthodontic force increased the distance of orthodontic tooth movement and the abundance of osteoclast. Transcriptome sequencing identified that Hdac9 was upregulated in the periodontal tissues of OIIRR rats compared to the control. Immunofluorescence revealed that HDAC9 was present in periodontal ligament fibroblasts, with reduced fluorescence of HDAC9 in OIIRR compared to the control. HDAC9 overexpression in hPDLFs induced pyroptosis and promoted osteoclast differentiation. These effects were reversed by pyroptosis inhibitor. CUT&Tag analysis showed that HDAC9 overexpression resulted in an enrichment of deacetylated genes on mitochondrial dysfunction-associated pathways. CUT&Tag-PCR analysis confirmed reduced H3K9ac enrichment on the mitochondrial dysfunction-associated genes VPS13D, AQP1, PEX2, CDK1, and PLEKHA1 after HDAC9 overexpression, and RT-qPCR analysis revealed a corresponding decrease in their respective expression levels. Accordingly, the ROS level was also increased by HDAC9 overexpression.

CONCLUSION

HDAC9-mediated histone deacetylation induces mitochondrial dysfunction and pyroptosis in hPDLFs, thereby promoting osteoclast differentiation and OIIRR progression.

CLINICAL RELEVANCE

This study reveals the regulatory mechanism of pyroptosis in OIIRR from the perspective of epigenetic modifications, providing new insights into the pathogenesis of OIIRR.

Relationship Between MCP-1 Levels in GCF and Periodontitis: A Systematic Review With Meta-Analysis and Analysis of Molecular Interactions

Monocyte chemoattractant protein 1 (MCP-1) is involved in monocyte chemotaxis, endothelial activation and regulation of leukocyte function in biological activities that promote inflammation, such as in periodontitis. A systematic review and meta-analysis was conducted with the primary objective of investigating the roles of MCP-1 in the gingival crevicular fluid (GCF) of subjects with chronic periodontitis compared to periodontally healthy subjects. The study protocol adhered to PRISMA guidelines. Digital searches were carried out across several databases, including PubMed, Dentistry & Oral Science Source, ScienceDirect, Scopus, Web of Science and Google Scholar. The quality of the studies was evaluated using the JBI tool for cross-sectional studies and clinical trials. To assess the concentration of MCP-1 in the GCF of the exposure group versus the control group, a meta-analysis was conducted employing a random-effects model. The search strategy yielded 1694 articles, with 14 studies meeting the inclusion criteria and 10 articles subjected to quantitative analysis. A total of 497 subjects were examined, comprising 298 cases and 199 controls. The meta-analysis indicated a significant increase in MCP-1 levels in the GCF of individuals with chronic periodontitis compared to healthy subjects (GCF: SMD = 20.29, 95% CI: 10.33-30.25, Z = 3.992, p = 0.001*). GCF MCP-1 levels are elevated in periodontitis compared to healthy controls, suggesting its potential future use as a diagnostic tool in clinical settings.

miR-223-3p Mitigates Mitochondrial Dysfunction and Cementoblast Apoptosis in Orthodontic Root Resorption via FoxO3

AIM

The aim of this study was to elucidate the roles of miR-223-3p in orthodontically induced inflammatory root resorption (OIIRR).

METHODS

We used high-throughput miRNA sequencing and transcriptome sequencing to analyze the differentially expressed miRNAs and mRNAs in OCCM-30 cells under hypoxia. Real-time quantitative PCR (RT-qPCR) and Western blotting were used to assess the expression of genes and proteins related to apoptosis, oxidative stress, and mitochondrial dysfunction. Fluorescence staining was employed to detect changes in cellular ROS (reactive oxygen species), MMP (mitochondrial membrane potential), and mtROS (mitochondrial ROS) expression.

RESULTS

We found that miR-223-3p targeted FoxO3 to regulate apoptosis in cementoblasts under hypoxic conditions. Moreover, hypoxia-induced FoxO3 increased oxidative stress and induced mitochondrial dysfunction in cementoblasts, resulting in cell apoptosis. Administration of the ROS inhibitor NAC (N-acetyl cysteine) effectively reversed FoxO3-induced oxidative stress and mitochondrial dysfunction, thereby rescuing cell apoptosis.

CONCLUSIONS

miR-223-3p targets FoxO3 and regulates the apoptosis of cementoblasts by improving oxidative stress and mitochondrial dysfunction. These findings may offer new insights into the mechanism of OIIRR.

Physiological occlusal force attenuates replacement root resorption of replanted teeth: an experimental animal study

BACKGROUND

Tooth avulsion represents the most severe form of dental trauma, necessitating tooth replantation as the primary treatment. However, the risk of replacement root resorption (RRR) poses a significant threat to tooth retention following replantation. This study preliminarily aimed to investigate the effect of physiological occlusal force on RRR after the replantation of avulsed teeth and to explore the potential underlying mechanisms.

METHODS

Thirty-six 4-week-old male Sprague-Dawley rats underwent extraction and immediate replantation of their left maxillary molars. The rats were randomly divided into two major groups: the occluded (n = 18) group, where the opposite mandibular teeth were preserved; non-occluded (n = 18) group, where the opposite mandibular teeth were extracted. Within each major group, there were three subgroups corresponding to 7 days, 14 days, and 2 months, resulting in a total of six subgroups, (n = 6 per subgroup). The right maxillary first molars served as the normal control. Various periodontal characteristics were assessed using haematoxylin-eosin (H&E), tartrate-resistant acid phosphatase (TRAP) staining, and micro-computed tomography (micro-CT).

RESULTS

Histological staining revealed that under occlusal force, the early stage (day 7) after tooth replantation mainly manifested as root surface resorption, especially in the non-occluded group, which gradually diminished over time. Cementum and periodontal ligament (PDL) repair was observed on day 14. Micro-CT analysis indicated a significant decrease in PDL width in the non-occluded group two months after replantation, consistent with the histological findings, signifying severe RRR in the non-occluded group.

CONCLUSIONS

This study provides preliminary evidence that physiological occlusal force may attenuate osteoclastogenesis during the early stage of tooth replantation, thereby reducing the occurrence of RRR and promoting periodontal healing.

MicroRNA-155 targets SOCS1 to inhibit osteoclast differentiation during orthodontic tooth movement

BACKGROUND

MicroRNA-155 (miR-155) is a multifunctional miRNA whose expression is known to be involved in a range of physiological and pathological processes. Its association with several oral diseases has been established. However, the specific role of miR-155 in orthodontic tooth movement remains unclear. In this study, we investigated the impact of miR-155 on osteoclast differentiation and orthodontic tooth movement models, aiming to explore the underlying mechanisms.

METHODS

In this experiment, we utilized various agents including miR-155 mimic, miR-155 inhibitor, as well as non-specific sequences (NC mimic & NC inhibitor) to treat murine BMMNCs. Subsequently, osteoclast induction (OC) was carried out to examine the changes in the differentiation ability of monocytes under different conditions. To assess these changes, we employed RT-PCR, Western blotting, and TRAP staining techniques. For the orthodontic tooth movement model in mice, the subjects were divided into two groups: the NaCl group (injected with saline solution) and the miR-155 inhibitor group (injected with AntagomiR-155). We observed the impact of orthodontic tooth movement using stereoscopic microscopy, micro-CT, and HE staining. Furthermore, we performed RT-PCR and Western blotting analyses on the tissues surrounding the moving teeth. Additionally, we employed TargetScan to predict potential target genes of miR-155.

RESULTS

During osteoclast induction of BMMNCs, the expression of miR-155 exhibited an inverse correlation with osteoclast-related markers. Overexpression of miR-155 led to a decrease in osteoclast-related indexes, whereas underexpression of miR-155 increased those indexes. In the mouse orthodontic tooth movement model, the rate of tooth movement was enhanced following injection of the miR-155 inhibitor, leading to heightened osteoclast activity. TargetScan analysis identified SOCS1 as a target gene of miR-155.

CONCLUSIONS

Our results suggest that miR-155 functions as an inhibitor of osteoclast differentiation, and it appears to regulate osteoclasts during orthodontic tooth movement. The regulatory mechanism of miR-155 in this process involves the targeting of SOCS1.

Circ_0114581 promotes osteogenic differentiation of BMSCs via the MiR-155-5p/HNRNPA3 axis

Osteoporosis (OP) is a common metabolic bone disease characterized by deterioration of bone tissue structure, reduction of bone mass, and susceptibility to fracture. More and new suitable therapeutic targets need to be discovered. The purpose of this study was to explore the ceRNA mechanisms of circRNAs involved in osteoporosis. In this study, a competing endogenous RNA (ceRNA) regulatory network was obtained through the application of OP-related high throughput data sets. Our results provided evidence that HNRNPA3 was involved in the regulation of osteogenic differentiation in BMSCs. Testing of human bone tissues and ovariectomized mice bones proved that its expression level was negatively correlated with OP. The utilization of miRNA mimic or inhibitor proved that miR-155-5p could negatively regulate the expression of HNRNPA3, while overexpression of hsa_circ_0114581 with a circRNA overexpression vector proved that hsa_circ_0114581 could indirectly promoted HNRNPA3 expression and osteogenic differentiation by sponging hsa-miR-155-5p. A serious of luciferase reporter assay experiments further verified the binding site between miR-155-5p and HNRNPA3 and the binding site between miR-155-5p and hsa_circ_0114581. This study proved that the hsa_circ_0114581/hsa-miR-155-5p/HNRNPA3 axis was related with OP. The results reveal valuable insights into the pathogenesis of OP and noncoding RNA markers that may have a treatment role and will help to provide hypotheses for future studies.

RANKL+ senescent cells under mechanical stress: a therapeutic target for orthodontic root resorption using senolytics

In dentistry, orthodontic root resorption is a long-lasting issue with no effective treatment strategy, and its mechanisms, especially those related to senescent cells, remain largely unknown. Here, we used an orthodontic intrusion tooth movement model with an L-loop in rats to demonstrate that mechanical stress-induced senescent cells aggravate apical root resorption, which was prevented by administering senolytics (a dasatinib and quercetin cocktail). Our results indicated that cementoblasts and periodontal ligament cells underwent cellular senescence (p21⁺ or p16⁺) and strongly expressed receptor activator of nuclear factor-kappa B (RANKL) from day three, subsequently inducing tartrate-resistant acid phosphatase (TRAP)-positive odontoclasts and provoking apical root resorption. More p21⁺ senescent cells expressed RANKL than p16⁺ senescent cells. We observed only minor changes in the number of RANKL⁺ non-senescent cells, whereas RANKL⁺ senescent cells markedly increased from day seven. Intriguingly, we also found cathepsin K⁺p21⁺p16⁺ cells in the root resorption fossa, suggesting senescent odontoclasts. Oral administration of dasatinib and quercetin markedly reduced these senescent cells and TRAP⁺ cells, eventually alleviating root resorption. Altogether, these results unveil those aberrant stimuli in orthodontic intrusive tooth movement induced RANKL⁺ early senescent cells, which have a pivotal role in odontoclastogenesis and subsequent root resorption. These findings offer a new therapeutic target to prevent root resorption during orthodontic tooth movement.

Role of noncoding RNAs in orthodontic tooth movement: new insights into periodontium remodeling

Orthodontic tooth movement (OTM) is biologically based on the spatiotemporal remodeling process in periodontium, the mechanisms of which remain obscure. Noncoding RNAs (ncRNAs), especially microRNAs and long noncoding RNAs, play a pivotal role in maintaining periodontal homeostasis at the transcriptional, post-transcriptional, and epigenetic levels. Under force stimuli, mechanosensitive ncRNAs with altered expression levels transduce mechanical load to modulate intracellular genes. These ncRNAs regulate the biomechanical responses of periodontium in the catabolic, anabolic, and coupling phases throughout OTM. To achieve this, down or upregulated ncRNAs actively participate in cell proliferation, differentiation, autophagy, inflammatory, immune, and neurovascular responses. This review highlights the regulatory mechanism of fine-tuning ncRNAs in periodontium remodeling during OTM, laying the foundation for safe, precise, and personalized orthodontic treatment.

MicroRNA Modulation during Orthodontic Tooth Movement: A Promising Strategy for Novel Diagnostic and Personalized Therapeutic Interventions

The Orthodontic Tooth Movement (OTM) is allowed through a mediated cell/tissue mechanism performed by applying a force or a pair of forces on the dental elements, and the tooth movement is a fundamental requirement during any orthodontic treatment. In this regard, it has been widely shown that each orthodontic treatment has a minimum duration required concerning numerous factors (age, patient compliance, type of technique used, etc.). In this regard, the aim of the following revision of the literature is to give readers a global vision of principal microRNAs (miRNAs) that are most frequently associated with OTM and their possible roles. Previously published studies of the last 15 years have been considered in the PubMed search using "OTM" and "miRNA" keywords for the present review article. In vitro and in vivo studies and clinical trials were mainly explored. Correlation between OTM and modulation of several miRNAs acting through post-transcriptional regulation on target genes was observed in the majority of previous studied. The expression analysis of miRNAs in biological samples, such as gingival crevicular fluid (GCF), can be considered a useful tool for novel diagnostic and/or prognostic approaches and for new personalized orthodontic treatments able to achieve a better clinical response rate. Although only a few studies have been published, the data obtained until now encourage further investigation of the role of miRNA modulation during orthodontic treatment. The aim of this study is to update the insights into the role and impact of principal micro-RNAs (miRNAs) that are most frequently associated during OTM.

Circulating MicroRNAs as Biomarkers of Osteoporosis and Fragility Fractures

CONTEXT

Measurement of circulating microRNAs (miRNAs) as potential biomarkers of fragility fracture risk has recently become a subject of investigation.

OBJECTIVE

Measure by next-generation sequencing (NGS), global miRNA expression in serum samples of osteoporotic subjects vs individuals with normal bone mineral density (BMD).

DESIGN

Samples were collected from patients with different bone phenotypes and/or fragility fractures who did not receive any antiresorptive and/or bone-forming drug at the time of blood collection.

SETTING

Samples and data were collected at 7 medical centers in Italy.

PATIENTS

NGS prescreening: 50 osteoporotic patients vs 30 individuals with normal BMD. Droplet digital polymerase chain reaction (ddPCR) validation: 213 patients with different bone phenotypes, including the NGS-analyzed cohort.

RESULTS

NGS identified 5 miRNAs (miR-8085, miR-320a-3p, miR-23a-3p, miR-4497, miR-145-5p) differentially expressed in osteoporosis cases without fractures vs controls. ddPCR validation confirmed lower c-miR-23a-3p expression in osteoporotic patients, with or without fracture, than in osteopenic and normal subjects and increased c-miR-320a-3p expression in osteoporotic patients with fracture and lower expression in osteoporotic patients without fracture. ddPCR analysis showed a significantly increased expression of miR-21-5p in osteoporotic patients, with or without fracture, than in osteopenic and normal subjects, not evidenced by the NGS prescreening.

DISCUSSION

Our study confirmed levels of c-miR-23a-3p and c-miR-21-5p as able to distinguish osteoporotic patients and subjects with normal BMD. Increased levels of c-miR-320a-3p specifically associated with fractures, independently by BMD, suggesting c-miR-320a-3p as a prognostic indicator of fracture risk in osteoporotic patients, to be confirmed in prospective studies on incident fractures.

Regulation of osteoclast-mediated bone resorption by microRNA

Osteoclast-mediated bone resorption is responsible for bone metabolic diseases, negatively impacting people's health and life. It has been demonstrated that microRNA influences the differentiation of osteoclasts by regulating the signaling pathways during osteoclast-mediated bone resorption. So far, the involved mechanisms have not been fully elucidated. This review introduced the pathways involved in osteoclastogenesis and summarized the related microRNAs binding to their specific targets to mediate the downstream pathways in osteoclast-mediated bone resorption. We also discuss the clinical potential of targeting microRNAs to treat osteoclast-mediated bone resorption as well as the challenges of avoiding potential side effects and producing efficient delivery methods.

CXCR2 Receptor: Regulation of Expression, Signal Transduction, and Involvement in Cancer

Chemokines are a group of about 50 chemotactic cytokines crucial for the migration of immune system cells and tumor cells, as well as for metastasis. One of the 20 chemokine receptors identified to date is CXCR2, a G-protein-coupled receptor (GPCR) whose most known ligands are CXCL8 (IL-8) and CXCL1 (GRO-α). In this article we present a comprehensive review of literature concerning the role of CXCR2 in cancer. We start with regulation of its expression at the transcriptional level and how this regulation involves microRNAs. We show the mechanism of CXCR2 signal transduction, in particular the action of heterotrimeric G proteins, phosphorylation, internalization, intracellular trafficking, sequestration, recycling, and degradation of CXCR2. We discuss in detail the mechanism of the effects of activated CXCR2 on the actin cytoskeleton. Finally, we describe the involvement of CXCR2 in cancer. We focused on the importance of CXCR2 in tumor processes such as proliferation, migration, and invasion of tumor cells as well as the effects of CXCR2 activation on angiogenesis, lymphangiogenesis, and cellular senescence. We also discuss the importance of CXCR2 in cell recruitment to the tumor niche including tumor-associated neutrophils (TAN), tumor-associated macrophages (TAM), myeloid-derived suppressor cells (MDSC), and regulatory T (T_reg) cells.