Disruption of Monocyte and Macrophage Homeostasis in Periodontitis

TPG-functionalized PLGA/PCL nanofiber membrane facilitates periodontal tissue regeneration by modulating macrophages polarization via suppressing PI3K/AKT and NF-κB signaling pathways

Traditional fibrous membranes employed in guided tissue regeneration (GTR) in the treatment of periodontitis have limitations of bioactive and immunomodulatory properties. We fabricated a novel nTPG/PLGA/PCL fibrous membrane by electrospinning which exhibit excellent hydrophilicity, mechanical properties and biocompatibility. In addition, we investigated its regulatory effect on polarization of macrophages and facilitating the regeneration of periodontal tissue both in vivo and in vitro. These findings showed the 0.5%TPG/PLGA/PCL may inhibit the polarization of RAW 264.7 into M1 phenotype by suppressing the PI3K/AKT and NF-κB signaling pathways. Furthermore, it directly up-regulated the expression of cementoblastic differentiation markers (CEMP-1 and CAP) in periodontal ligament stem cells (hPDLSCs), and indirectly up-regulated the expression of cementoblastic (CEMP-1 and CAP) and osteoblastic (ALP, RUNX2, COL-1, and OCN) differentiation markers by inhibiting the polarization of M1 macrophage. Upon implantation into a periodontal bone defect rats model, histological assessment revealed that the 0.5%TPG/PLGA/PCL membrane could regenerate oriented collagen fibers and structurally intact epithelium. Micro-CT (BV/TV) and the expression of immunohistochemical markers (OCN, RUNX-2, COL-1, and BMP-2) ultimately exhibited satisfactory regeneration of alveolar bone, periodontal ligament. Overall, 0.5%TPG/PLGA/PCL did not only directly promote osteogenic effects on hPDLSCs, but also indirectly facilitated cementoblastic and osteogenic differentiation through its immunomodulatory effects on macrophages. These findings provide a novel perspective for the development of materials for periodontal tissue regeneration.

Relationship Between Diabetes Mellitus and Periodontal/Peri-Implant Disease: A Contemporaneous Review

The prevalence of diabetes mellitus (DM), a major chronic disease and a leading cause of death and disability around the world, is rising. According to the latest data, the global prevalence of DM has increased to 463 million (9.3% of adults) in 2019 and is estimated to reach 700 million by 2045. Periodontal disease, result of periodontium inflammation, is a common, chronic disease and has long been considered one of the complications of DM. Moreover, literature reflects a spectrum of conflicting viewpoints on the effect of diabetic conditions on the implant treatment strategies. The current review aims to update the recent epidemiologic evidence regarding the relationship between DM and periodontal/peri-implant disease, emphasising the effects of glycaemic control on the severity of these diseases and describing the pathobiological mechanisms underlying this association. This review's findings indicate a bidirectional relationship between DM and periodontal/peri-implant disease and that this relationship seems causal, implying that controlling these two diseases might help prevent each other's incidence. Additionally, the severity of periodontal/peri-implant disease is directly related to metabolic control. Although patients with diabetes can obtain implant success similar to those in systemically healthy individuals, an increased risk of peri-implantitis has been reported in DM patients. Therefore, the importance of glycaemic control and maintaining proper oral hygiene cannot be overstated.

IRE1α regulates macrophage polarization in type 2 diabetic periodontitis through promoting endoplasmic reticulum stress

OBJECTIVES

The aim of this study was to investigate the effect of 4μ8c, an inhibitor targeting the endoplasmic reticulum stress-associated factor IRE1α, on macrophage polarization in an experimental model of diabetic periodontitis through ex vivo experiments.

MATERIALS AND METHODS

Local alveolar bone parameters were evaluated using Micro-CT following intraperitoneal administration of 4μ8c in mice with experimental diabetic periodontitis. Surface markers indicating macrophage polarization were identified using immunofluorescence. In vitro experiments were performed employing bone marrow-derived macrophages and gingival fibroblasts. Macrophage polarization was determined using flow cytometry. Principal impacted signaling pathways were identified through Western blot analysis.

RESULTS

Results from both in vitro and in vivo experiments demonstrated that 4μ8c mitigated alveolar bone resorption and inflammation in mice with diabetic periodontitis. Furthermore, it modulated macrophage polarization towards the M2 phenotype and augmented M2 macrophage polarization through the MAPK signaling pathway.

CONCLUSIONS

These findings suggest that inhibiting IRE1α can modulate macrophage polarization and alleviate ligature-induced diabetic periodontitis via the MAPK signaling pathway. This unveils a novel mechanism, offering a scientific foundation for the treatment of experimental diabetic periodontitis.

Dynamic hydrogel-metal-organic framework system promotes bone regeneration in periodontitis through controlled drug delivery

Periodontitis is a prevalent chronic inflammatory disease, which leads to gradual degradation of alveolar bone. The challenges persist in achieving effective alveolar bone repair due to the unique bacterial microenvironment's impact on immune responses. This study explores a novel approach utilizing Metal-Organic Frameworks (MOFs) (comprising magnesium and gallic acid) for promoting bone regeneration in periodontitis, which focuses on the physiological roles of magnesium ions in bone repair and gallic acid's antioxidant and immunomodulatory properties. However, the dynamic oral environment and irregular periodontal pockets pose challenges for sustained drug delivery. A smart responsive hydrogel system, integrating Carboxymethyl Chitosan (CMCS), Dextran (DEX) and 4-formylphenylboronic acid (4-FPBA) was designed to address this problem. The injectable self-healing hydrogel forms a dual-crosslinked network, incorporating the MOF and rendering its on-demand release sensitive to reactive oxygen species (ROS) levels and pH levels of periodontitis. We seek to analyze the hydrogel's synergistic effects with MOFs in antibacterial functions, immunomodulation and promotion of bone regeneration in periodontitis. In vivo and in vitro experiment validated the system's efficacy in inhibiting inflammation-related genes and proteins expression to foster periodontal bone regeneration. This dynamic hydrogel system with MOFs, shows promise as a potential therapeutic avenue for addressing the challenges in bone regeneration in periodontitis.

Polarized M2 macrophages induced by glycosylated nano-hydroxyapatites activate bone regeneration in periodontitis therapy

AIM

To investigate the association between periodontal macrophage polarization states and the alveolar bone levels, and to assess whether glycosylated nano-hydroxyapatites (GHANPs) could improve bone regeneration in periodontitis by inducing macrophage M2 polarization.

MATERIALS AND METHODS

The change of macrophage polarization state in inflammatory periodontal tissues (with bone loss) was examined using clinical gingival samples. The relationship between macrophage phenotype and bone level in periodontal bone loss and repair was evaluated using a mouse periodontitis model. The effect of GHANPs on macrophage polarization was assessed by the in vitro model of lipopolysaccharide (LPS)-stimulated inflammation. The polarization-related markers were detected by immunofluorescence staining, real-time polymerase chain reaction and enzyme-linked immunosorbent assay analysis. The therapeutic effect of GHANPs on alveolar bone loss was explored in experimental periodontitis by histological staining and micro-CT analysis.

RESULTS

A lower macrophage M2/M1 ratio was observed in periodontitis-affected human gingival tissues. The results of animal experiments demonstrated a positive correlation between a lower Arg-1/iNOS ratio and accelerated alveolar bone loss; also, the proportion of Arg-1-positive macrophages increased during bone repair and regeneration. The administration of GHANPs partially restored M2 macrophage polarization after LPS stimulation. GHANPs increased alveolar bone repair and regeneration in experimental periodontitis induced by ligation, potentially related to their macrophage M2 transition regulation.

CONCLUSIONS

The findings of this study indicate that the induction of macrophage M2 polarization can be considered a viable approach for enhancing inflammatory bone repair. Additionally, GHANPs show potential in the clinical treatment of periodontitis.

Global trends in research on aging associated with periodontitis from 2002 to 2023: a bibliometric analysis

Background

Aging has been implicated in many chronic inflammatory diseases, including periodontitis. Periodontitis is an inflammatory disease caused by long-term irritation of the periodontal tissues by the plaque biofilm on the surface of the teeth. However, only a few bibliometric analyses have systematically studied this field to date. This work sought to visualize research hot spots and trends in aging associated with periodontitis from 2002 to 2023 through bibliometric approaches.

Methods

Graphpad prism v8.0.2 was used to analyse and plot annual papers, national publication trends and national publication heat maps. In addition, CtieSpace (6.1.6R (64-bit) Advanced Edition) and VOSviewer (version 1.6.18) were used to analyse these data and visualize the scientific knowledge graph.

Results

The number of documents related to aging associated with periodontitis has steadily increased over 21 years. With six of the top ten institutions in terms of publications coming from the US, the US is a major driver of research in this area. journal of periodontology is the most published journal in the field. Tonetti MS is the most prolific authors and co-cited authors in the field. Journal of Periodontology and Journal of Clinical Periodontology are the most popular journals in the field with the largest literature. Periodontitis, Alzheimer's disease, and peri-implantitis are current hot topics and trends in the field. Inflammation, biomarkers, oxidative stress cytokines are current research hotspots in this field.

Conclusion

Our research found that global publications regarding research on aging associated with periodontitis increased dramatically and were expected to continue increasing. Inflammation and aging, and the relationship between periodontitis and systemic diseases, are topics worthy of attention.

Piezoelectric hydrogel for treatment of periodontitis through bioenergetic activation

The impaired differentiation ability of resident cells and disordered immune microenvironment in periodontitis pose a huge challenge for bone regeneration. Herein, we construct a piezoelectric hydrogel to rescue the impaired osteogenic capability and rebuild the regenerative immune microenvironment through bioenergetic activation. Under local mechanical stress, the piezoelectric hydrogel generated piezopotential that initiates osteogenic differentiation of inflammatory periodontal ligament stem cells (PDLSCs) via modulating energy metabolism and promoting adenosine triphosphate (ATP) synthesis. Moreover, it also reshapes an anti-inflammatory and pro-regenerative niche through switching M1 macrophages to the M2 phenotype. The synergy of tilapia gelatin and piezoelectric stimulation enhances in situ regeneration in periodontal inflammatory defects of rats. These findings pave a new pathway for treating periodontitis and other immune-related bone defects through piezoelectric stimulation-enabled energy metabolism modulation and immunomodulation.

Immunosenescence and inflammaging: Conspiracies against alveolar bone turnover

OBJECTIVE

Inflammaging and immunosenescence are characteristics of senescent immune system alterations. This review provides insights into inflammaging and immunosenescence in periodontitis and focuses on the innerlink of inflammaging and immunosenescence in alveolar bone turnover from a perspective of cell-cell interaction.

METHODS

This review is conducted by a narrative approach to discuss the effect of inflammaging and immunosenescence in aging-related alveolar bone loss. A comprehensive literature research in PubMed and Google was applied to identify reports in English.

RESULTS

Inflammaging is concerned with abnormal M1 polarization and increasing circulating inflammatory cytokines, while immunosenescence involves reduced infection and vaccine responses, depressed antimicrobial function, and infiltration of aged B cells and memory T cells. TLR-mediated inflammaging and altered adaptive immunity significantly affect alveolar bone turnover and aggravate aging-related alveolar bone loss. Besides, energy consumption also plays a vital role in aged immune and skeletal system of periodontitis.

CONCLUSIONS

Senescent immune system exerts a significant function in aging-related alveolar bone loss. Inflammaging and immunosenescence interact functionally and mechanistically, which affects alveolar bone turnover. Therefore, further clinical treatment strategies targeting alveolar bone loss could be based on the specific molecular mechanism connecting inflammaging, immunosenescence, and alveolar bone turnover.

Identifying MS4A6A+ macrophages as potential contributors to the pathogenesis of nonalcoholic fatty liver disease, periodontitis, and type 2 diabetes mellitus

Purpose

Concrete epidemiological evidence has suggested the mutually-contributing effect respectively between nonalcoholic fatty liver disease (NAFLD), type 2 diabetes mellitus (T2DM), and periodontitis (PD); however, their shared crosstalk mechanism remains an open issue.

Method

The NAFLD, PD, and T2DM-related datasets were obtained from the NCBI GEO repository. Their common differentially expressed genes (DEGs) were identified and the functional enrichment analysis performed by the DAVID platform determined relevant biological processes and pathways. Then, the STRING database established a PPI network of such DEGs and topological analysis through Cytoscape 3.7.1 software along with the machine-learning analysis by the least absolute shrinkage and selection operator (LASSO) algorithm screened out hub characteristic genes. Their efficacy was validated by external datasets using the receiver operating characteristic (ROC) curve, and gene expression and location of the most robust one was determined using single-cell sequencing and immunohistochemical staining. Finally, the promising drugs were predicted through the CTD database, and the CB-DOCK 2 and Pymol platform mimicked molecular docking.

Result

Intersection of differentially expressed genes from three datasets identified 25 shared DEGs of the three diseases, which were enriched in MHC II-mediated antigen presenting process. PPI network and LASSO machine-learning analysis determined 4 feature genes, of which the MS4A6A gene mainly expressed by macrophages was the hub gene and key immune cell type. Molecular docking simulation chosen fenretinide as the most promising medicant for MS4A6A+ macrophages.

Conclusion

MS4A6A+ macrophages were suggested to be important immune-related mediators in the progression of NAFLD, PD, and T2DM pathologies.

Bioinformatics analysis revealed the potential crosstalk genes and molecular mechanisms between intracranial aneurysms and periodontitis

OBJECTIVES

The risk of intracranial aneurysms (IAs) development and rupture is significantly higher in patients with periodontitis (PD), suggesting an association between the two. However, the specific mechanisms of association between these two diseases have not been fully investigated.

MATERIALS AND METHODS

In this study, we downloaded IAs and PD data from the Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified, and functional enrichment analysis was performed. The protein-protein interaction (PPI) network and weighted gene co-expression network analysis (WGCNA) was performed to identified key modules and key crosstalk genes. In addition, the immune cell landscape was assessed and the correlation of key crosstalk genes with each immune cell was calculated. Finally, transcription factors (TFs) regulating key crosstalk genes were explored.

RESULTS

127 overlapping DEGs were identified and functional enrichment analysis highlighted the important role of immune reflection in the pathogenesis of IAs and PD. We identified ITGAX and COL4A2 as key crosstalk genes. In addition, the expression of multiple immune cells was significantly elevated in PDs and IAs compared to controls, and both key crosstalk genes were significantly negatively associated with Macrophages M2. Finally, GATA2 was identified as a potential key transcription factor (TF), which regulates two key crosstalk gene.

CONCLUSIONS

The present study identifies key crosstalk genes and TF in PD and IAs, providing new insights for further study of the co-pathogenesis of PD and IAs from an immune and inflammatory perspective. Also, this is the first study to report the above findings.

Metronidazole may display anti-inflammatory features in periodontitis treatment: A scoping review

AIM

Metronidazole (MTZ) is an antimicrobial agent used to treat anaerobic infections. It has been hypothesized that MTZ may also have anti-inflammatory properties, but the evidence is limited and has not been previously reviewed. Thus, this scoping review aimed to answer the following question: "What is the evidence supporting anti-inflammatory properties of metronidazole that are not mediated by its antimicrobial effects?"

METHODS

A scoping review was conducted according to the PRISMA-ScR statement. Five databases were searched up to January 2023 for studies evaluating the anti-inflammatory properties of MTZ used as monotherapy for treating infectious and inflammatory diseases.

RESULTS

A total of 719 records were identified, and 27 studies (21 in vivo and 6 in vitro) were included. The studies reported experimental evidence of MTZ anti-inflammatory effects on (1) innate immunity (barrier permeability, leukocyte adhesion, immune cell populations), (2) acquired immunity (lymphocyte proliferation, T-cell function, cytokine profile), and (3) wound healing/resolution of inflammation.

CONCLUSION

Taken together, this scoping review supported a potential anti-inflammatory effect of MTZ in periodontitis treatment. We recommend that future clinical studies should be conducted to evaluate specific MTZ anti-inflammatory pathways in the treatment of periodontitis.

Macrophage-derived exosomes rescue the TNF-ɑ-suppressed osteo-/cementogenic differentiation of hPDLCs

OBJECTIVE

Inflammatory stimuli compromise the differentiation potency of human periodontal ligament cells (hPDLCs). Macrophage-derived exosomes (M-Exo) play a role in several aspects of cellular activity. This study investigated how M-Exo contributes to the osteo-/cementogenic differentiation of hPDLCs under inflammation and the mechanism involved.

METHODS

M-Exo was identified by transmission electron microscopy, western blotting (WB), and dynamic light scattering. The internalization of M-Exo by hPDLCs was observed. After M-Exo treatment, the osteo-/cementogenic markers were detected by RT-qPCR and WB, and alkaline phosphatase (ALP) activity by ALP staining. Tumor necrosis factor alpha (TNF-ɑ) was applied to simulate inflammation. The rescue effect of M-Exo on TNF-ɑ-suppressed differentiation was validated. The p38 MAPK pathway activity was tested and a specific inhibitor was applied to explore the mechanism.

RESULTS

M-Exo was successfully isolated, identified and internalized by hPDLCs. M-Exo enhanced the osteo-/cementogenic differentiation of hPDLCs, as indicated by upregulated osteo-/cementogenic markers and elevated ALP activity. Moreover, TNF-ɑ inhibited the differentiation capabilities of hPDLCs, on which M-Exo showed a rescue effect. M-Exo activated the p38 MAPK pathway and SB203580 attenuated its promotion effect.

CONCLUSION

This study showed that M-Exo ameliorated the TNF-ɑ-suppressed osteo-/cementogenic differentiation of hPDLCs partly through the p38 MAPK pathway.

The potential crosstalk genes and molecular mechanisms between glioblastoma and periodontitis

Despite clinical and epidemiological evidence suggestive of a link between glioblastoma (GBM) and periodontitis (PD), the shared mechanisms of gene regulation remain elusive. In this study, we identify differentially expressed genes (DEGs) that overlap between the GEO datasets GSE4290 [GBM] and GSE10334 [PD]. Functional enrichment analysis was conducted, and key modules were identified using protein-protein interaction (PPI) network and weighted gene co-expression network analysis (WGCNA). The expression levels of CXCR4, LY96, and C3 were found to be significantly elevated in both the test dataset and external validation dataset, making them key crosstalk genes. Additionally, immune cell landscape analysis revealed elevated expression levels of multiple immune cells in GBM and PD compared to controls, with the key crosstalk genes negatively associated with Macrophages M2. FLI1 was identified as a potential key transcription factor (TF) regulating the three key crosstalk genes, with increased expression in the full dataset. These findings contribute to our understanding of the immune and inflammatory aspects of the comorbidity mechanism between GBM and PD.

Periodic Lamellae-Based Nanofibers for Precise Immunomodulation to Treat Inflammatory Bone Loss in Periodontitis

Periodontitis is a common oral disease accompanied by inflammatory bone loss. The pathological characteristics of periodontitis usually accompany an imbalance in the periodontal immune microenvironment, leading to difficulty in bone regeneration. Therefore, effective treatment strategies are needed to modulate the immune environment in order to treat periodontitis. Here, highly-oriented periodic lamellae poly(ε-caprolactone) electrospun nanofibers (PLN) are developed by surface-directed epitaxial crystallization. The in vitro result shows that the PLN can precisely modulate macrophage polarization toward the M2 phenotype. Macrophages polarized by PLN significantly enhance the migration and osteogenic differentiation of Bone marrow stromal cells, Scanning electron microscopy. Notably, results suggest that the topographical cues presented by PLN can modulate macrophage polarization by activating YAP, which reciprocally inhibits the NF-κB signaling pathway. The in vivo results indicate that PLN can inhibit inflammatory bone loss and facilitate bone regeneration in periodontitis. The authors' findings suggest that topographical nanofibers with periodic lamellae is a promising strategy for modulating immune environment to treat inflammatory bone loss in periodontitis.

P53 Alleviates the Progression of Periodontitis by Reducing M1-type Macrophage Differentiation

Our objective is to explore the effect of P53 on the progression of periodontitis by regulating macrophages differentiation both in vitro and in vivo. Eighteen normal and periodontitis gingival tissues were collected for detecting P53 expression and macrophages infiltration by immunofluorescence, real-time PCR (qPCR) and western-blot. The differentiation and the inflammatory cytokines (TNF-α and IL-6) expression of THP-1, RAW264.7 and bone marrow derived macrophage (BMDM) cells, treating with Pifithrin-α (P53 inhibitor) or Nutlin-3a (P53 activator) under lipopolysaccharide (LPS) stimulation, were observed by flow cytometry, qPCR and ELISA. The severity of periodontitis, inflammatory cytokines expression and macrophages infiltration were measured in experimental periodontitis wild-type mice and p53 gene conditional knocked-out (p53-CKO) mice, which were established by ligation and LPS injection. A higher number of P53-positive macrophages was found infiltrated in periodontitis tissues. In vitro experiments showed that compared with Nutlin-3a, the proportion of M1-type macrophages and the expression of TNF-α and IL-6 were higher in Pifithrin-α treated cells under LPS stimulation. In vivo experimental periodontitis mice, the Pifithrin-α intraperitoneal injection group showed greater alveolar bone loss, higher levels of TNF-α and IL-6 secretion and more M1-type macrophages infiltration, while the Nutlin-3a intraperitoneal injection group were observed mild symptoms compared with mice in the periodontitis group. P53-CKO mice exhibited more severe periodontitis and more M1-type macrophages infiltrated in local tissues compared with wild-type mice. The activation of p53 gene could alleviate periodontitis by reducing M1-type macrophage polarization. P53 may serve as keeper in the progression of periodontitis, providing new insights into periodontitis treatment.

Interleukin-37 ameliorates periodontitis development by inhibiting NLRP3 inflammasome activation and modulating M1/M2 macrophage polarization

OBJECTIVE

Our study was designed to explore the role of IL-37 in M1/M2 macrophage polarization imbalance in the pathogenesis of periodontitis.

BACKGROUND

Periodontitis is a chronic progressive inflammatory disease featured by gingival inflammation and alveolar bone resorption. Recent research has revealed that regulating macrophage polarization is a viable method to ameliorate periodontal inflammation. IL-37 is an anti-inflammatory cytokine, which has been reported to inhibit innate and adaptive immunity.

METHODS

For in vitro experiment, mouse macrophage RAW264.7 cells were pretreated with 0.1 ng/mL recombinant human IL-37. M1 and M2 polarizations of RAW264.7 cells were induced by 100 ng/mL LPS and 20 ng/mL IL-4, respectively. The expression of M1 (iNOS, TNF-α, and IL-6) and M2 (CD206, Arg1, and IL-10) phenotype markers in RAW264.7 cells was detected by RT-qPCR, western blotting, and immunofluorescence staining. For in vivo experiment, experimental periodontitis mouse models were established by sterile silk ligation (5-0) around the bilateral maxillary second molar of mice for 1 week. H&E staining of the maxillary alveolar bone was used to show the resorption of root cementum and dentin. Alveolar bone loss in mouse models was evaluated through micro-CT analysis. The expression of iNOS and CD206 in gingival tissues was assessed by immunohistochemistry staining. NLRP3 inflammasome activation was confirmed by western blotting.

RESULTS

IL-37 pretreatment reduced iNOS, TNF-α, and IL-6 expression in LPS-treated RAW264.7 cells but increased CD206, Arg1, and IL-10 in IL-4-treated RAW264.7 cells. LPS-induced upregulation in NLRP3, GSDMD, cleaved-IL-1β, and cleaved-caspase-1 expression was antagonized by IL-37 treatment. In addition, IL-37 administration ameliorated the resorption of root cementum and dentin in periodontitis mouse models. IL-37 prominently decreased iNOS+ cell population but increased CD206+ cell population in gingival tissues of periodontitis mice. The enhancement in NLRP3, GSDMD, cleaved-IL-1β, and cleaved-caspase-1 expression in the gingival tissues of periodontitis mice was offset by IL-37 administration.

CONCLUSION

IL-37 prevents the progression of periodontitis by suppressing NLRP3 inflammasome activation and mediating M1/M2 macrophage polarization.

Single-cell RNA sequencing combined with proteomics of infected macrophages reveals prothymosin-α as a target for treatment of apical periodontitis

INTRODUCTION

Chronic apical periodontitis (CAP) is a common infectious disease of the oral cavity. Immune responses and osteoclastogenesis of monocytes/macrophages play a crucial role in CAP progression, and this study want to clarify role of monocytes/macrophages in CAP, which will contribute to treatment of CAP.

OBJECTIVES

We aim to explore the heterogeneity of monocyte populations in periapical lesion of CAP tissues and healthy control (HC) periodontal tissues by single-cell RNA sequencing (scRNA-seq), search novel targets for alleviating CAP, and further validate it by proteomics and in vitro and in vivo evaluations.

METHODS

ScRNA-seq was used to analyze the heterogeneity of monocyte populations in CAP, and proteomics of THP-1-derived macrophages with porphyromonas gingivalis infection were intersected with the differentially expressed genes (DEGs) of macrophages between CAP and HC tissues. The upregulated PTMA (prothymosin-α) were validated by immunofluorescence staining and quantitative real time polymerase chain reaction. We evaluated the effect of thymosin α1 (an amino-terminal proteolytic cleavage product of PTMA protein) on inflammatory factors and osteoclast differentiation of macrophages infected by P. gingivalis. Furthermore, we constructed mouse and rat mandibular bone lesions caused by apical periodontitis, and estimated treatment of systemic and topical administration of PTMA for CAP. Statistical analyses were performed using GraphPad Prism software (v9.2) RESULTS: Monocytes were divided into seven sub-clusters comprising monocyte-macrophage-osteoclast (MMO) differentiation in CAP. 14 up-regulated and 21 down-regulated genes and proteins were intersected between the DEGs of scRNA-seq data and proteomics, including the high expression of PTMA. Thymosin α1 may decrease several inflammatory cytokine expressions and osteoclastogenesis of THP-1-derived macrophages. Both systemic administration in mice and topical administration in the pulp chamber of rats alleviated periapical lesions.

CONCLUSIONS

PTMA upregulation in CAP moderates the inflammatory response and prevents the osteoclastogenesis of macrophages, which provides a basis for targeted therapeutic strategies for CAP.

Advancements in innate immune regulation strategies in islet transplantation

As a newly emerging organ transplantation technique, islet transplantation has shown the advantages of minimal trauma and high safety since it was first carried out. The proposal of the Edmonton protocol, which has been widely applied, was a breakthrough in this method. However, direct contact between islets and portal vein blood will cause a robust innate immune response leading to massive apoptosis of the graft, and macrophages play an essential role in the innate immune response. Therefore, therapeutic strategies targeting macrophages in the innate immune response have become a popular research topic in recent years. This paper will summarize and analyze recent research on strategies for regulating innate immunity, primarily focusing on macrophages, in the field of islet transplantation, including drug therapy, optimization of islet preparation process, islet engineering and Mesenchymal stem cells cotransplantation. We also expounded the heterogeneity, plasticity and activation mechanism of macrophages in islet transplantation, providing a theoretical basis for further research.

The Genetic Aspects of Periodontitis Pathogenesis and the Regenerative Properties of Stem Cells

Periodontitis (PD) is a prevalent and chronic inflammatory disease with a complex pathogenesis, and it is associated with the presence of specific pathogens, such as Porphyromonas gingivalis. Dysbiosis and dysregulated immune responses ultimately lead to chronic inflammation as well as tooth and alveolar bone loss. Multiple studies have demonstrated that genetic polymorphisms may increase the susceptibility to PD. Furthermore, gene expression is modulated by various epigenetic mechanisms, such as DNA methylation, histone modifications, or the activity of non-coding RNA. These processes can also be induced by PD-associated pathogens. In this review, we try to summarize the genetic processes that are implicated in the pathogenesis of PD. Furthermore, we discuss the use of these mechanisms in diagnosis and therapeutic purposes. Importantly, novel treatment methods that could promote tissue regeneration are greatly needed in PD. In this paper, we also demonstrate current evidence on the potential use of stem cells and extracellular vesicles to stimulate tissue regeneration and suppress inflammation. The understanding of the molecular mechanisms involved in the pathogenesis of PD, as well as the impact of PD-associated bacteria and stem cells in these processes, may enhance future research and ultimately improve long-term treatment outcomes.

CCL2 is a key regulator and therapeutic target for periodontitis

AIM

Our previous study revealed that the C-C motif chemokine receptor 2 (CCR2) is a promising target for periodontitis prevention and treatment. However, CCR2 is a receptor with multiple C-C motif chemokine ligands (CCLs), including CCL2, CCL7, CCL8, CCL13 and CCL16, and which of these ligands plays a key role in periodontitis remains unclear. The aim of the present study was to explore the key functional ligand of CCR2 in periodontitis and to evaluate the potential of the functional ligand as a therapeutic target for periodontitis.

MATERIALS AND METHODS

The expression levels and clinical relevance of CCR2, CCL2, CCL7, CCL8, CCL13 and CCL16 were studied using human samples. The role of CCL2 in periodontitis was evaluated by using CCL2 knockout mice and overexpressing CCL2 in the periodontium. The effect of local administration of bindarit in periodontitis was evaluated by preventive and therapeutic medication in a mouse periodontitis model. Microcomputed tomography, haematoxylin and eosin staining, tartrate-resistant acid phosphatase staining, real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, bead-based immunoassays and flow cytometry were used for histomorphology, molecular biology and cytology analysis.

RESULTS

Among different ligands of CCR2, only CCL2 was significantly up-regulated in periodontitis gingival tissues and was positively correlated with the severity of periodontitis. Mice lacking CCL2 showed milder inflammation and less bone resorption than wild-type mice, which was accompanied by a reduction in monocyte/macrophage recruitment. Adeno-associated virus-2 vectors overexpressing CCL2 in Ccl2-/- mice gingiva reversed the attenuation of periodontitis in a CCR2-dependent manner. In ligation-induced experimental periodontitis, preventive or therapeutic administration of bindarit, a CCL2 synthesis inhibitor, significantly inhibited the production of CCL2, decreased the osteoclast number and bone loss and reduced the expression levels of proinflammatory cytokines TNF-α, IL-6 and IL-1β.

CONCLUSIONS

CCL2 is a pivotal chemokine that binds to CCR2 during the progression of periodontitis, and targeting CCL2 may be a feasible option for controlling periodontitis.

Hyperglycaemia aggravates periodontal inflamm-aging by promoting SETDB1-mediated LINE-1 de-repression in macrophages

AIM

To explore whether hyperglycaemia plays a role in periodontal inflamm-aging by inducing phenotypical transformation of macrophages, as well as the potential mechanism via SET domain-bifurcated histone lysine methyltransferase 1 (SETDB1).

MATERIALS AND METHODS

A hyperglycaemic mouse model was established using streptozotocin injection. The alveolar bone was analysed using micro-computed tomography. Periodontal inflamm-aging was detected using western blotting, quantitative real-time PCR and immunohistochemical analysis. In vitro, RAW 264.7 macrophages were incubated with various doses of glucose. siRNA or overexpression plasmids were used to determine the regulatory mechanism of SETDB1 in macrophage senescence and inflamm-aging under hyperglycaemic conditions. Expression and distribution of SETDB1 and long interspersed element 1 (LINE-1) in gingival tissues of patients with or without diabetes were detected using immunofluorescent staining.

RESULTS

SETDB1 expression in the periodontal tissues of patients and mice with diabetes was down-regulated compared with that in non-diabetic controls. SETDB1 deficiency induced senescence-like phenotypical changes in macrophages, which aggravated periodontal inflamm-aging in diabetic mice. Furthermore, metformin treatment rejuvenated SETDB1 activity and alleviated the hyperglycaemia-induced periodontal inflamm-aging.

CONCLUSIONS

The findings of this study show that SETDB1 regulates senescence-like phenotypical switching of macrophages and is a potential candidate for the treatment of diabetes-induced periodontal inflamm-aging.

Kynurenic acid inhibits macrophage pyroptosis by suppressing ROS production via activation of the NRF2 pathway

Macrophage pyroptosis and related inflammatory responses play an important role in periodontitis. Kynurenic acid (KA) is hypothesized to have anti‑inflammatory potential, but whether KA can inhibit macrophage pyroptosis and the underlying mechanisms remain unclear. Lipopolysaccharide (LPS) was used to induce pyroptosis in THP‑1‑derived macrophages. KA or ML385 was used to pretreat macrophages, after which, cell viability, NOD‑like receptor protein 3 (NLRP3) inflammasome‑related protein expression, oxidative stress levels and nuclear factor erythroid 2‑related factor 2 (NRF2) expression were measured. The results showed that KA improved the LPS‑induced decrease in macrophage viability and lactate dehydrogenase release. KA prevented THP‑1 macrophage pyroptosis induced by LPS by reducing the expression of NLRP3, Gasdermin‑D, and Caspase1, and decreased the expression of inflammatory factors. KA suppressed NLRP3 inflammasome activation by inhibiting ROS overproduction and increasing Heme Oxygenase 1 and glutathione levels. Moreover, KA promoted NRF2 translocation from the cytoplasm to the nucleus. In addition, the anti‑pyroptotic and antioxidant effects of KA were reversed by ML385 inhibition of NRF2. In the present study, it was found that KA significantly suppressed macrophage pyroptosis induced by LPS. It was further demonstrated that the anti‑pyroptotic effects of KA were mediated by activation of the NRF2 pathway.

PLEKHA4 promotes glioblastoma progression through apoptosis inhibition, tumor cell migration, and macrophage infiltration

BACKGROUND

Glioblastoma(GBM) has a profound impact on human health, making the identification of reliable prognostic biomarkers pivotal. While PLEKHA4 has been associated with tumor genesis and development, its role in gliomas is still uncertain.

METHODS

We analyzed PLEKHA4 expression in tumor tissues using the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Additionally, we utilized TCGA data to investigate its impact on prognosis, pathway enrichment, and immune infiltration. In vitro loss-of-function experiments were conducted to elucidate the effect of PLEKHA4 silencing on GBM cell behavior.

RESULTS

TCGA and GEO data sets revealed increased levels of PLEKHA4 expression in glioma tissues. Furthermore, we identified a correlation between PLEKHA4 expression and higher disease classification, pathological grading, and poorer prognosis. Silencing PLEKHA4 in vitro resulted in decreased glioma cell migration and increased apoptosis. It also reduced macrophage infiltration and hindered M2 polarization of macrophages.

CONCLUSION

Our findings highlight the pivotal role of PLEKHA4 in GBM pathogenesis and suggest its potential as a diagnostic and therapeutic target for GBM.

Modulation of monocyte subtypes in diabetes after non-surgical periodontal treatment

OBJECTIVES

The current study aims to evaluate the effect of non-surgical periodontal treatment on the modulation of monocyte phenotype, in the presence or absence of diabetes.

MATERIALS AND METHODS

The identification, quantification, and phenotypic characterization of monocyte subtypes (classical, intermediate, and non-classical) were performed by flow cytometry, at baseline and 1 month after the end of non-surgical periodontal treatment, in patients with periodontitis, associated or not with diabetes.

RESULTS

There was an increase in non-classical monocytes after treatment and a reduction in intermediate monocytes, without differences for the classical subtype, regardless of the diabetes status. Furthermore, there was a reduction in intermediate monocytes and an increase in non-classical and classical monocytes after treatment in the diabetes group, while no significant differences were observed for classical, intermediate, and non-classical monocytes in the group without diabetes. Comparisons between the two groups showed significant differences for classical, intermediate, and non-classical monocytes at baseline; these differences were not found one month after treatment.

CONCLUSIONS

Non-surgical periodontal treatment leads to modulation of monocytes to a less inflammatory phenotype, especially in individuals with diabetes.

CLINICAL RELEVANCE

A better understanding of the role of these biomarkers in the periodontitis contex may constitute a new strategic target for a better treatment of patiens with diabetes associated to periodontitis.

CLINICAL TRIAL REGISTRATION

Brazilian Registry of Clinical Trials-RBR-35szwc. Jhefferson Miranda Alves and Danielle Borges Germano contributed equality to this study and should be considered first authors.

Alterations in macrophage polarization play a key role in control and development of periodontal diseases

Periodontitis is a chronic inflammatory disease driven by complex interplays between a dysbiotic oral microbiome and a dysregulated host inflammatory response that results in the destruction of the tooth-supporting apparatus. Among the inflammatory cells involved in the pathogenesis of periodontitis, macrophages are recruited early on to sites of periodontal infection. These cells can polarize in different phenotypes that mediate the initiation and resolution of inflammatory responses, as well as in tissue healing. Macrophage phenotypic plasticity is thought to play a critical role in the induction and resolution of inflammation and may be compromised in patients with chronic inflammatory diseases. Here, we reviewed the role of macrophage polarization in periodontal disease and therapy.

Systemic Type 2 Inflammation-Associated Atopic Dermatitis Exacerbates Periodontitis

INTRODUCTION

Atopic dermatitis (AD) is a prevalent and chronic inflammatory skin disease characterized by Th2 cell-mediated type 2 inflammation. Emerging evidence indicated that AD patients exhibit an increased incidence of oral disorders. In the present study, we sought mechanistic insights into how AD affects periodontitis.

METHODS

Onset of AD was induced by 2,4-dinitrochlorobenzene (DNCB). Furthermore, we induced periodontitis (P) in AD mice. The effect of AD in promoting inflammation and bone resorption in gingiva was evaluated. Hematoxylin and eosin staining, tartrate-resistant acid phosphatase staining, immunofluorescence assay, and flow cytometry were used to investigate histomorphology and cytology analysis, respectively. RNA sequencing of oral mucosa is used tissues to further understand the dynamic transcriptome changes. 16S rRNA microbial analysis is used to profile oral microbial composition.

RESULTS

Compared to control group, mice in AD group showed inflammatory signatures and infiltration of a proallergic Th2 (Th2A)-like subset in oral mucosa but not periodontitis, as identified by not substantial changes in mucosa swelling, alveolar bone loss, and TRAP+ osteoclasts infiltration. Similarly, more Th2A-like cell infiltration and interleukin-4 levels were significantly elevated in the oral mucosa of DNCB-P mice compared to P mice. More importantly, AD exacerbates periodontitis when periodontitis has occurred and the severity of periodontitis increased with aggravation of dermatitis. Transcriptional analysis revealed that aggravated periodontitis was positively correlated with more macrophage infiltration and abundant CCL3 secreted. AD also altered oral microbiota, indicating the re-organization of extracellular matrix.

CONCLUSIONS

These data provide solid evidence about exacerbation of periodontitis caused by type 2 dermatitis, advancing our understanding in cellular and microbial changes during AD-periodontitis progression.

Proteomic and single-cell analysis shed new light on the anti-inflammatory role of interferonβ in chronic periodontitis

Periodontitis, a condition that results in periodontal attachment loss and alveolar bone resorption, contributes to the global burden of oral disease. The underlying mechanism of periodontitis involves the dysbiosis and dyshomeostasis between host and oral microbes, among which the macrophage is one of the major innate immune cell players, producing interferon β (IFNβ) in response to bacterial infection. The objective of this research was to examine the interaction of macrophages with periodontitis and the role and mechanism of IFNβ on macrophages. IFNβ has been shown to have the potential to induce the differentiation of M1 to M2 macrophages, which are stimulated by low levels of lipopolysaccharide (LPS). Additionally, IFNβ has been demonstrated to promote the production of ISG15 by macrophages, which leads to the inhibition of the innate immune response. Moreover, our investigation revealed that IFNβ has the potential to augment the secretion of ISG15 and its downstream cytokine, IL10, in LPS-stimulated macrophages. Single-cell analysis was conducted on the gingival tissues of patients with periodontitis, which revealed a higher proportion of macrophages in the periodontitis-diseased tissue and increased expression of IFNβ, ISG15, and IL10. Gene Set Enrichment Analysis indicated that bacterial infection was associated with upregulation of IFNβ, ISG15, and IL10. Notably, only IL10 has been linked to immunosuppression, indicating that the IFNβ-ISG15-IL10 axis might promote an anti-inflammatory response in periodontitis through IL10 expression. It is also found that macrophage phenotype transitions in periodontitis involve the release of higher levels of IFNβ, ISG15, and IL10 by the anti-inflammatory M2 macrophage phenotype compared to the pro-inflammatory M1 phenotype and myeloid-derived suppressor cells (MDSCs). This implies that the IFNβ-induced production of IL10 might be linked to the M2 macrophage phenotype. Furthermore, cell communication analysis demonstrated that IL10 can promote fibroblast proliferation in periodontal tissues via STAT3 signaling.

The homeostasis and therapeutic applications of innate and adaptive immune cells in periodontitis

OBJECTIVES

Periodontitis (PD) is one of the most common dental disorders. This chronic oral inflammation is caused by complicated interrelations between bacterial infections, dysregulated immune reactions, and environmental risk factors. A dysregulated immune response can lead to inflammatory bone resorption by allowing the recruitment of pro-inflammatory immune cells to the periodontal tissues.

SUBJECTS

The recruitment of innate and adaptive immune cells in PD initiates the acute and following chronic inflammatory processes. The inflamed tissues, on the other hand, can be restored if the anti-inflammatory lineages are predominantly established in the periodontal tissues. Therefore, we aimed to review the published literature to provide an overview of the existing knowledge about the role of immune cells in PD, as well as their possible therapeutic applications.

RESULTS

Experimental studies showed that drugs/systems that negatively regulate inflammatory cells in the body, as well as interventions aimed at increasing the number of anti-inflammatory cells such as Tregs and Bregs, can both help in the healing process of PD.

CONCLUSION

Targeting immune cells or their positive/negative manipulations has been demonstrated to be an effective therapeutic method. However, to use this sort of immunotherapy in humans, further pre-clinical investigations, as well as randomized clinical trials, are required.

Glipizide Alleviates Periodontitis Pathogenicity via Inhibition of Angiogenesis, Osteoclastogenesis and M1/M2 Macrophage Ratio in Periodontal Tissue

New consensus indicates type 2 diabetes mellitus (T2DM) and periodontitis as comorbidity and may share common pathways of disease progression. Sulfonylureas have been reported to improve the periodontal status in periodontitis patients. Glipizide, a sulfonylurea widely used in the treatment of T2DM, has also been reported to inhibit inflammation and angiogenesis. The effect of glipizide on the pathogenicity of periodontitis, however, has not been studied. We developed ligature-induced periodontitis in mice and treated them with different concentrations of glipizide and then analyzed the level of periodontal tissue inflammation, alveolar bone resorption, and osteoclast differentiation. Inflammatory cell infiltration and angiogenesis were analyzed using immunohistochemistry, RT-qPCR, and ELISA. Transwell assay and Western bolt analyzed macrophage migration and polarization. 16S rRNA sequencing analyzed the effect of glipizide on the oral microbial flora. mRNA sequencing of bone marrow-derived macrophages (BMMs) stimulated by P. gingivalis lipopolysaccharide (Pg-LPS) after treatment with glipizide was analyzed. Glipizide decreases alveolar bone resorption, periodontal tissue degradation, and the number of osteoclasts in periodontal tissue affected by periodontitis (PAPT). Glipizide-treated periodontitis mice showed reduced micro-vessel density and leukocyte/macrophage infiltration in PAPT. Glipizide significantly inhibited osteoclast differentiation in vitro experiments. Glipizide treatment did not affect the oral microbiome of periodontitis mice. mRNA sequencing and KEGG analysis showed that glipizide activated PI3K/AKT signaling in LPS-stimulated BMMs. Glipizide inhibited the LPS-induced migration of BMMs but promoted M2/M1 macrophage ratio in LPS-induced BMMs via activation of PI3K/AKT signaling. In conclusion, glipizide inhibits angiogenesis, macrophage inflammatory phenotype, and osteoclastogenesis to alleviate periodontitis pathogenicity suggesting its' possible application in the treatment of periodontitis and diabetes comorbidity.

Revealing a potential necroptosis-related axis (RP11-138A9.1/hsa-miR-98-5p/ZBP1) in periodontitis by construction of the ceRNA network

BACKGROUND AND OBJECTIVES

Periodontitis, a prevalent chronic inflammatory condition, poses a significant risk of tooth loosening and subsequent tooth loss. Within the realm of programmed cell death, a recently recognized process known as necroptosis has garnered attention for its involvement in numerous inflammatory diseases. Nevertheless, its correlation with periodontitis is indistinct. Our study aimed to identify necroptosis-related lncRNAs and crucial lncRNA-miRNA-mRNA regulatory axes in periodontitis to further understand the pathogenesis of periodontitis.

MATERIALS AND METHODS

Gene expression profiles in gingival tissues were acquired from the Gene Expression Omnibus (GEO) database. Selecting hub necroptosis-related lncRNA and extracting the key lncRNA-miRNA-mRNA axes based on the ceRNA network by adding novel machine-learning models based on conventional analysis and combining qRT-PCR validation. Then, an artificial neural network (ANN) model was constructed for lncRNA in regulatory axes, and the accuracy of the model was validated by receiver operating characteristic (ROC) curve analysis. The clinical effect of the model was evaluated by decision curve analysis (DCA). Weighted correlation network analysis (WGCNA) and single-sample gene set enrichment analysis (ssGSEA) was performed to explore how these lncRNAs work in periodontitis.

RESULTS

Seven hub necroptosis-related lncRNAs and three lncRNA-miRNA-mRNA regulatory axes (RP11-138A9.1/hsa-miR-98-5p/ZBP1 axis, RP11-96D1.11/hsa-miR-185-5p/EZH2 axis, and RP4-773 N10.4/hsa-miR-21-5p/TLR3 axis) were predicted. WGCNA revealed that RP11-138A9.1 was significantly correlated with the "purple module". Functional enrichment analysis and ssGSEA demonstrated that the RP11-138A9.1/hsa-miR-98-5p/ZBP1 axis is closely related to the inflammation and immune processes in periodontitis.

CONCLUSION

Our study predicted a crucial necroptosis-related regulatory axis (RP11-138A9.1/hsa-miR-98-5p/ZBP1) based on the ceRNA network, which may aid in elucidating the role and mechanism of necroptosis in periodontitis.

The nano-windmill exerts superior anti-inflammatory effects via reducing choline uptake to inhibit macrophage activation

Macrophages' activation plays a central role during the development and progression of inflammation, while the regulation of metabolic reprogramming of macrophages has been recently identified as a novel strategy for anti-inflammatory therapies. Our previous studies have found that tetrahedral framework nucleic acid (tFNA) plays a mild anti-inflammatory effect by inhibiting macrophage activation, but the specific mechanism remains unclear. Here, by metabolomics and RNA sequencing, choline uptake is identified to be significantly repressed by decreased slc44a1 expression in tFNA-treated activated macrophages. Inspired by this result, combined with the excellent delivery capacities of tFNA, siR-slc44a1 is loaded into the tFNA to develop a new tFNA-based small interfering RNA (siRNA) delivery system named 'nano-windmill,' which exhibits a synergetic role by targeting slc44a1, finally blowing up the anti-inflammatory effects of tFNA to inhibit macrophages activation via reducing choline uptake. By confirming its anti-inflammatory effects in chronic (periodontitis) and acute (sepsis) inflammatory disease, the tFNA-based nanomedicine developed for inflammatory diseases may provide broad prospects for tFNA upgrading and various biological applications such as anti-inflammatory.

Small Extracellular Vesicles from Periodontal Ligament Stem Cells Primed by Lipopolysaccharide Regulate Macrophage M1 Polarization via miR-433-3p Targeting TLR2/TLR4/NF-κB

Lipopolysaccharide (LPS) is regarded as the main pathogenic factor of periodontitis. Mesenchymal stem cell-derived small extracellular vesicles (sEVs) play a key role in a variety of physiological and pathological processes. This study investigated the effects of sEVs derived from periodontal ligament stem cells (PDLSCs) pretreated with LPS on macrophage polarization and the underlying mechanisms. PDLSCs were treated with LPS (1 µg/mL) for 24 h, and sEVs were harvested by gradient centrifugation method. Macrophages were incubated with sEVs for 24 h, followed by examination of the expression profiles of inflammatory and anti-inflammatory cytokines, and polarization markers. Furthermore, microarray analysis, western blot test, and microRNA inhibitor transfection experiments were used to elucidate the molecular signaling pathway responsible for the process. The results showed that sEVs derived from LPS-preconditioning PDLSCs could significantly increase the expression of M1 markers and inflammatory cytokines, whereas decreased the expression of M2 markers and anti-inflammatory cytokines. Mechanistic analysis showed that TLR2/TLR4/NF-κB p65 pathway was involved in M1 polarization of macrophages, and microRNA-433-3p played a role, at least in part, in the course. Collectively, LPS could promote the macrophages into M1 status via TLR2/TLR4/NF-κB p65 signaling pathway partly by sEV-mediated microRNA-433-3p, which could be a potential therapeutic target for periodontitis.

Dental Pulp Stem Cell-Derived Exosomes Regulate Anti-Inflammatory and Osteogenesis in Periodontal Ligament Stem Cells and Promote the Repair of Experimental Periodontitis in Rats

Purpose

Dental pulp stem cell-derived exosomes (DPSC-EXO), which have biological characteristics similar to those of metrocytes, have been found to be closely associated with tissue regeneration. Periodontitis is an immune inflammation and tissue destructive disease caused by plaque, resulting in alveolar bone loss and periodontal epithelial destruction. It is not clear whether DPSC-EXO can be used as an effective therapy for periodontal regeneration. The purpose of this study was not only to verify the effect of DPSC-EXO on reducing periodontitis and promoting periodontal tissue regeneration, but also to reveal the possible mechanism.

Methods

DPSC-EXO was isolated by ultracentrifugation. Then it characterized by transmission electron microscope (TEM), nanoparticle tracking analysis (NTA) and Western Blot. In vitro, periodontal ligament stem cells (PDLSCs) were treated with DPSC-EXO, the abilities of cell proliferation, migration and osteogenic potential were evaluated. Furthermore, we detected the expression of IL-1β, TNF-αand key proteins in the IL-6/JAK2/STAT3 signaling pathway after simulating the inflammatory environment by LPS. In addition, the effect of DPSC-EXO on the polarization phenotype of macrophages was detected. In vivo, the experimental periodontitis in rats was established and treated with DPSC-EXO or PBS. After 4 weeks, the maxillae were collected and detected by micro-CT and histological staining.

Results

DPSC-EXO promoted the proliferation, migration and osteogenesis of PDLSCs in vitro. DPSC-EXO also regulated inflammation by inhibiting the IL-6/JAK2/STAT3 signaling pathway during acute inflammatory stress. In addition, the results showed that DPSC-EXO could polarize macrophages from the M1 phenotype to the M2 phenotype. In vivo, we found that DPSC-EXO could effectively reduce alveolar bone loss and promote the healing of the periodontal epithelium in rats with experimental periodontitis.

Conclusion

DPSC-EXO plays an important role in inhibiting periodontitis and promoting tissue regeneration. This study provides a promising acellular therapy for periodontitis.

TIPE2 regulates periodontal inflammation by inhibiting NF-κB p65 phosphorylation

BACKGROUND

The roles and molecular mechanisms of tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) in periodontitis remain largely unknown.

OBJECTIVE

This study aimed to determine the expression of TIPE2 and NF-κB p65 in rat Porphyromonas gingivalis-induced periodontics in vivo.

METHODOLOGY

Periodontal inflammation and alveolar bone resorption were analyzed using western blotting, micro-computed tomography, TRAP staining, immunohistochemistry, and immunofluorescence. THP-1 monocytes were stimulated using 1 μg/ml Pg. lipopolysaccharide (Pg.LPS) to determine the expression of TIPE2 in vitro. TIPE2 mRNA was suppressed by siRNA transfection, and the transfection efficiency was proven using western blotting and real-time PCR. The NF-κB pathway was activated by treating the cells with 1 μg/ml Pg.LPS to explore related mechanisms.

RESULTS

The expression of both TIPE2 and NF-κB p65 was increased in the gingival tissues of rat periodontitis compared with normal tissues. Positive expression of TIPE2 was distributed in inflammatory infiltrating cells and osteoclasts in the marginal lacunae of the alveolar bone. However, strong positive expression of TIPE2 in THP-1 was downregulated after Pg.LPS stimulation. TIPE2 levels negatively correlated with TNF-α and IL-1β. Decreased TIPE2 in THP-1 further promoted NF-κB p65 phosphorylation. Mechanistically, TIPE2 knockdown upregulated NF-κB signaling pathway activity.

CONCLUSIONS

Taken together, these findings demonstrate that TIPE2 knockdown aggravates periodontal inflammatory infiltration via NF-κB pathway. Interventions aimed at increasing TIPE2 may help in the therapeutic applications for periodontitis.

Uncovering the potential role of oxidative stress in the development of periodontitis and establishing a stable diagnostic model via combining single-cell and machine learning analysis

Background

The primary pathogenic cause of tooth loss in adults is periodontitis, although few reliable diagnostic methods are available in the early stages. One pathological factor that defines periodontitis pathology has previously been believed to be the equilibrium between inflammatory defense mechanisms and oxidative stress. Therefore, it is necessary to construct a model of oxidative stress-related periodontitis diagnostic markers through machine learning and bioinformatic analysis.

Methods

We used LASSO, SVM-RFE, and Random Forest techniques to screen for periodontitis-related oxidative stress variables and construct a diagnostic model by logistic regression, followed by a biological approach to build a Protein-Protein interaction network (PPI) based on modelled genes while using modelled genes. Unsupervised clustering analysis was performed to screen for oxidative stress subtypes of periodontitis. we used WGCNA to explore the pathways correlated with oxidative stress in periodontitis patients. Networks. Finally, we used single-cell data to screen the cellular subpopulations with the highest correlation by scoring oxidative stress genes and performed a proposed temporal analysis of the subpopulations.

Results

We discovered 3 periodontitis-associated genes (CASP3, IL-1β, and TXN). A characteristic line graph based on these genes can be helpful for patients. The primary hub gene screened by the PPI was constructed, where immune-related and cellular metabolism-related pathways were significantly enriched. Consistent clustering analysis found two oxidative stress categories, with the C2 subtype showing higher immune cell infiltration and immune function ratings. Therefore, we hypothesized that the high expression of oxidative stress genes was correlated with the formation of the immune environment in patients with periodontitis. Using the WGCNA approach, we examined the co-expressed gene modules related to the various subtypes of oxidative stress. Finally, we selected monocytes for mimetic time series analysis and analyzed the expression changes of oxidative stress genes with the mimetic time series axis, in which the expression of JUN, TXN, and IL-1β differed with the change of cell status.

Conclusion

This study identifies a diagnostic model of 3-OSRGs from which patients can benefit and explores the importance of oxidative stress genes in building an immune environment in patients with periodontitis.

Incomplete Polymerization of Dual-Cured Resin Cement Due to Attenuated Light through Zirconia Induces Inflammatory Responses

Zirconia restorations are becoming increasingly common. However, zirconia reduces the polymerization of dual-cured resin cement owing to light attenuation, resulting in residual resin monomers. This study investigated the effects of dual-cured resin cement, with incomplete polymerization owing to attenuated light through zirconia, on the inflammatory response in vitro. The dual-cured resin cement (SA Luting Multi, Kuraray) was light-irradiated through zirconia with three thickness diameters (1.0, 1.5, and 2.0 mm). The light transmittance and the degree of conversion (DC) of the resin cement significantly decreased with increasing zirconia thickness. The dual-cured resin cement in 1.5 mm and 2.0 mm zirconia and no-irradiation groups showed significantly higher amounts of hydroxyethylmethacrylate and triethyleneglycol dimethacrylate elution and upregulated gene expression of proinflammatory cytokines IL-1β and IL-6 from human gingival fibroblasts (hGFs) and TNFα from human monocytic cells, compared with that of the 0 mm group. Dual-cured resin cement with lower DC enhanced intracellular reactive oxygen species (ROS) levels and activated mitogen-activated protein (MAP) kinases in hGFs and monocytic cells. This study suggests that dual-cured resin cement with incomplete polymerization induces inflammatory responses in hGFs and monocytic cells by intracellular ROS generation and MAP kinase activation.

New insights into inflammatory osteoclast precursors as therapeutic targets for rheumatoid arthritis and periodontitis

Rheumatoid arthritis (RA) and periodontitis are chronic inflammatory diseases leading to increased bone resorption. Preventing this inflammatory bone resorption is a major health challenge. Both diseases share immunopathogenic similarities and a common inflammatory environment. The autoimmune response or periodontal infection stimulates certain immune actors, leading in both cases to chronic inflammation that perpetuates bone resorption. Moreover, RA and periodontitis have a strong epidemiological association that could be explained by periodontal microbial dysbiosis. This dysbiosis is believed to be involved in the initiation of RA via three mechanisms. (i) The dissemination of periodontal pathogens triggers systemic inflammation. (ii) Periodontal pathogens can induce the generation of citrullinated neoepitopes, leading to the generation of anti-citrullinated peptide autoantibodies. (iii) Intracellular danger-associated molecular patterns accelerate local and systemic inflammation. Therefore, periodontal dysbiosis could promote or sustain bone resorption in distant inflamed joints. Interestingly, in inflammatory conditions, the existence of osteoclasts distinct from "classical osteoclasts" has recently been reported. They have proinflammatory origins and functions. Several populations of osteoclast precursors have been described in RA, such as classical monocytes, a dendritic cell subtype, and arthritis-associated osteoclastogenic macrophages. The aim of this review is to synthesize knowledge on osteoclasts and their precursors in inflammatory conditions, especially in RA and periodontitis. Special attention will be given to recent data related to RA that could be of potential value in periodontitis due to the immunopathogenic similarities between the two diseases. Improving our understanding of these pathogenic mechanisms should lead to the identification of new therapeutic targets involved in the pathological inflammatory bone resorption associated with these diseases.

Association of vitamin K, fibre intake and progression of periodontal attachment loss in American adults

BACKGROUND

Periodontitis-related attachment loss is accompanied by mucosal bleeding and inflammatory lesions. Dietary vitamin K and fibre intake are known to be correlation factors of haemostasis and anti-inflammation, respectively.

OBJECTIVE

To explore the association between severe periodontal attachment loss and vitamin K or fibre intake in American adults.

METHODS

A cross-sectional analysis was conducted including 2747 males and 2218 females in the National Health and Nutrition Examination Surveys (NHANES) from 2009 to 2014. The number of teeth with severe periodontal attachment loss (above 5 mm attachment loss) was used as the dependent variable. The main independent variables included the intake of vitamin K and dietary fibre. The association among variables was examined using multivariable linear regression models, hierarchical regression, fitted smoothing curves, and generalized additive models.

RESULTS

Based on the indicators of 4965 subjects, we found that severe attachment loss tended to occur in elderly individuals or males and was accompanied by less intake of vitamin K or dietary fibre, as well as lower educational qualification. Vitamin K intake was stably negatively associated with attachment loss progression in each multivariable linear regression model. In subgroup analyses, a negative association between fibre intake and attachment loss progression was identified in all races except blacks (β = 0.0005, 95% CI: -0.0005 to 0.0016). The relationship between fibre intake and attachment loss progression was a broad U-shaped curve (inflection point: 753.4 mg), which especially manifested in males (inflection point: 967.5 mg).

CONCLUSION

There was an inverse association between vitamin K intake and the progression of periodontal attachment loss in American adults, while dietary fibre should be moderate in intake (below 753.4 mg), especially in males (below 967.5 mg).

Aspirin loaded extracellular vesicles inhibit inflammation of macrophages via switching metabolic phenotype in periodontitis

OBJECTIVES

Changes of macrophage in the local immune microenvironment of periodontitis cause alveolar bone resorption. This study aims to investigate the effect of a new drug delivery method of aspirin on the immune microenvironment of periodontitis to promote alveolar bone repair, and to explore mechanism of aspirin's effect on macrophage.

METHODS

We isolated extracellular vesicles (EVs) from periodontal stem cells (PDLSCs) and loaded with aspirin by sonication, and then evaluated the treatment efficacy of aspirin-loaded vesicles (EVs-ASP) in periodontitis model in mice. In vitro, we explored the role of EVs-ASP in the regulation of LPS-induced macrophages. The underlying mechanism by which EVs-ASP regulates phenotypic remodeling of macrophages in periodontitis was further investigated.

RESULTS

EVs-ASP inhibited the inflammatory environment of LPS-induced macrophage, and promoted anti-inflammatory macrophages formation both in vivo and in vitro, and reduced bone loss in periodontitis models. Moreover, EVs-ASP enhanced oxidative phosphorylation and suppressed glycolysis in macrophages.

CONCLUSIONS

Consequently, EVs-ASP improves the periodontal immune microenvironment by enhancing oxidative phosphorylation (OXPHOS) in macrophages, resulting in a certain degree of regeneration of alveolar bone height. Our study provides a new potential strategy for bone repair in periodontitis therapy.

Molecular events in the jaw vascular unit: A traditional review of the mechanisms involved in inflammatory jaw bone diseases

Inflammatory jaw bone diseases are common in stomatology, including periodontitis, peri-implantitis, medication-related osteonecrosis of the jaw, radiation osteomyelitis of the jaw, age-related osteoporosis, and other specific infections. These diseases may lead to tooth loss and maxillofacial deformities, severely affecting patients' quality of life. Over the years, the reconstruction of jaw bone deficiency caused by inflammatory diseases has emerged as a medical and socioeconomic challenge. Therefore, exploring the pathogenesis of inflammatory diseases associated with jaw bones is crucial for improving prognosis and developing new targeted therapies. Accumulating evidence indicates that the integrated bone formation and dysfunction arise from complex interactions among a network of multiple cell types, including osteoblast-associated cells, immune cells, blood vessels, and lymphatic vessels. However, the role of these different cells in the inflammatory process and the 'rules' with which they interact are still not fully understood. Although many investigations have focused on specific pathological processes and molecular events in inflammatory jaw diseases, few articles offer a perspective of integration. Here, we review the changes and mechanisms of various cell types in inflammatory jaw diseases, with the hope of providing insights to drive future research in this field.

Glycolytic reprogramming controls periodontitis-associated macrophage pyroptosis via AMPK/SIRT1/NF-κB signaling pathway

Glycolysis has been demonstrated as a crucial metabolic process in bacteria infected diseases via modulating the activity of pyroptosis. Macrophages are the most abundant immune cells that infiltrated in the infected periodontal tissues, which significantly influence the outcome of periodontitis (PD). However, the effect of glycolysis in regulating macrophage pyroptosis during PD development remains unknown. This study aimed to explore the role of glycolysis in PD-associated macrophage pyroptosis and periodontal degeneration. Clinical specimens were used to determine the emergence of macrophage pyroptosis and glycolysis in periodontal tissues by immunohistochemical analysis and western blot. For an in-depth understanding of the regulatory effect of glycolysis in the progression of macrophage pyroptosis associated periodontitis, both in vivo PD model and in vitro PD model were treated with 2-DG (2-Deoxy-d-glucose), a glycolysis inhibitor. The data showed that the blockade of glycolysis could significantly suppress the lipopolysaccharide (LPS) induced macrophage pyroptosis, resulting in an attenuation of the inflammatory response and bone resorption in periodontal lesions. Furthermore, we revealed that the regulatory effect of glycolysis on macrophage pyroptosis can be mediated via AMPK/SIRT1/NF-κB signaling pathway. Our study unveiled that suppressed glycolysis restrains the activity of PD-associated macrophage pyroptosis, osteoclastogenesis, and subsequent periodontal tissue destruction. These findings extend our knowledge of glycolysis in regulating PD-associated macrophage pyroptosis and provide a potential novel target for PD therapy.

Development of a classification model and an immune-related network based on ferroptosis in periodontitis

BACKGROUND AND OBJECTIVES

Periodontitis is an immunoinflammatory disease characterized by irreversible periodontal attachment loss and bone destruction. Ferroptosis is a kind of immunogenic cell death that depends on the participation of iron ions and is involved in various inflammatory and immune processes. However, information regarding the relationship between ferroptosis and immunomodulation processes in periodontitis is extremely limited. The purpose of this study was to investigate the correlation between ferroptosis and immune responses in periodontitis.

METHODS

Gene expression profiles of gingivae were collected from the Gene Expression Omnibus data portal. After detecting differentially expressed ferroptosis-related genes (FRGs), we used univariate logistic regression analysis followed by logistic least absolute shrinkage and selection operator (LASSO) regression to establish a ferroptosis-related classification model in an attempt to accurately distinguish periodontitis gingival tissues from healthy samples. The infiltration level of immunocytes in periodontitis was then assessed through single-sample gene-set enrichment analysis. Subsequently, we screened out immune-related genes by weighted correlation network analysis and protein-protein interaction (PPI) analysis and constructed an immune-related network based on FRGs and immune-related genes.

RESULTS

A total of 24 differentially expressed FRGs were detected, and an 8-FRG combined signature constituted the classification model. The established model showed outstanding discriminating ability according to the results of receiver operating characteristic (ROC) curve analysis. In addition, the periodontitis samples had a higher degree of immunocyte infiltration. Activated B cells had the strongest positive correlation while macrophages had a strong negative correlation with certain FRGs, and we found that XBP1, ALOX5 and their interacting genes might be crucial genes in the immune-related network.

CONCLUSIONS

The FRG-based classification model had a satisfactory determination ability, which could bring new insights into the pathogenesis of periodontitis. Those genes in the immune-related network, especially hub genes along with XBP1 and ALOX5, would have the potential to serve as promising targets of immunomodulatory treatments for periodontitis.

A comprehensive multiparameter flow cytometry panel for immune profiling and functional studies of frozen tissue, bone marrow, and spleen

Flow cytometry (FC) is a highly informative technology that can provide valuable information about immune phenotype monitoring and immune cell states. However, there is a paucity of comprehensive panels developed and validated for use on frozen samples. Here, we developed a 17-plex flow cytometry panel to detect subtypes, frequencies, and functions of different immune cells that can be leveraged to study the different cellular characteristics in different disease models, physiological, and pathological conditions. This panel identifies surface markers to characterize T cells (CD8+, CD4+), natural killer (NK) cells and their subtypes (immature, cytotoxic, exhausted, activated),natural killer T (NKT) cells, neutrophils, macrophages (M1 (pro-inflammatory) and M2 (anti-inflammatory)), monocytes and their subtypes (classical and non-classical), dendritic cells (DC) and their subtypes (DC1, DC2), and eosinophils. The panel was designed to include only surface markers to avoid the necessity for fixation and permeabilization steps. This panel was optimized using cryopreserved cells. Immunophenotyping of spleen and bone marrow using the proposed panel was efficient in correctly differentiating the immune cell subtypes in inflammatory model of ligature-induced periodontitis, in which we found increased percentage of NKT cells, activated and mature/cytotoxic NK cells in the bone marrow of affected mice. This panel enables in-depth immunophenotyping of murine immune cells in bone marrow, spleen, tumors, and other non-immune tissues of mice. It could be a tool for systematic analysis of immune cell profiling in inflammatory conditions, systemic diseases, and tumor microenvironments.

Effect of Probiotics Lactobacillus acidophilus and Lacticaseibacillus rhamnosus on Antibacterial Response Gene Transcription of Human Peripheral Monocytes

Periodontitis and related systemic inflammatory diseases are characterized by imbalanced ratio between pro- and anti-inflammatory factors. Probiotics may control inflammation by altering the inflammatory phenotype of defense cells. We aimed to evaluate the gene transcription of the antibacterial response of monocytes to exposure to probiotic lactobacilli. CD14 + monocytes were obtained by positive selection from peripheral blood mononuclear cells from healthy donors (5 × 10⁴ CD14 + /mL) and cultured with probiotic strains of Lacticaseibacillus rhamnosus (LR-32) and Lactobacillus acidophilus (LA-5) at a 1:10 multiplicity of infection in 24-well plates for 12 h. The gene expression analysis was performed by RT-qPCR using the Kit RT² human antibacterial response, and in the supernatant, the cytokines were determined by ELISA. Tukey's post hoc test following an ANOVA with a p value of 5% was used for statistical analysis. Both probiotic strains increased the levels of cytokines TNF-α and CXCL-8 in the supernatant compared to the control of non-challenged cells (p < 0.05), but for IL-1Β and IL-6, this effect was observed only for LA-5 (p < 0.05). The fold-regulation values for the following genes for LA-5 and LR-32 were, respectively, IL-12B (431.94 and 33.30), IL-1Β (76.73 and 17.14), TNF-α (94.63 and 2.49), CXCL-8 (89.59 and 4.18), and TLR-2 (49.68 and 3.40). Likewise, most of the other genes evaluated showed greater expression for LA-5 compared to LR-32 (p < 0.05). The positive regulation of inflammatory factors such as IL-1β promoted by L. acidophilus LA-5 may increase the antibacterial activity of innate defense in periodontal tissues. However, this property may be deleterious by increasing inflammatory response.

Dental Follicle Stem Cells Promote Periodontal Regeneration through Periostin-Mediated Macrophage Infiltration and Reprogramming in an Inflammatory Microenvironment

Dental follicle stem cells (DFSCs) have been verified to promote periodontal regeneration in an inflammatory microenvironment. When coping with inflammatory stimulation, DFSCs highly express periostin, a bioactive molecule closely related to periodontal homeostasis. It is worth exploring whether and how periostin plays a role in the promotion of periodontal regeneration by DFSCs. By tracking the fate of DFSCs, it was found that DFSCs significantly contributed to periodontal regeneration in rat periodontal defects while they had a low survival rate. They highly expressed periostin and improved the immune microenvironment in the defect area, especially via the recruitment and reprogramming of macrophages. Silencing periostin attenuated the effects of DFSCs in promoting periodontal regeneration and regulating macrophages. Recombinant human periostin (rhPeriostin) could not only directly promote macrophage reprogramming through the integrin αM/phosphorylated extracellular signal-regulated kinase (p-Erk)/Erk signaling pathway, but it also exhibited the potential to promote periodontal regeneration in rats when loaded in a collagen matrix. These results indicated that periostin is actively involved in the process by which DFSCs promote periodontal regeneration through the regulation of macrophages and is a promising molecular agent to promote periodontal regeneration. This study provides new insight into the mechanism by which DFSCs promote periodontal regeneration and suggests a new approach for periodontal regeneration therapy.

The interaction between innate immunity and oral microbiota in oral diseases

INTRODUCTION

Innate immunity serves as the frontline to combat invading pathogens. Oral microbiota is the total collection of microorganisms colonized within the oral cavity. By recognizing the resident microorganisms through pattern recognition receptors, innate immunity is capable of interacting with oral microbiota and maintaining homeostasis. Dysregulation of interaction may lead to the pathogenesis of several oral diseases. Decoding the crosstalk between oral microbiota and innate immunity may be contributory to developing novel therapies for preventing and treating oral diseases.

AREAS COVERED

This article reviewed pattern recognition receptors in the recognition of oral microbiota, the reciprocal interaction between innate immunity and oral microbiota, and discussed how the dysregulation of this relationship leads to the pathogenesis and development of oral diseases.

EXPERT OPINION

Many studies have been conducted to illustrate the relationship between oral microbiota and innate immunity and its role in the occurrence of different oral diseases. The impact and mechanisms of innate immune cells on oral microbiota and the mechanisms of dysbiotic microbiota in altering innate immunity are still needed to be investigated. Altering the oral microbiota might be a possible solution for treating and preventing oral diseases.

Single-Cell Analyses of the Oral Mucosa Reveal Immune Cell Signatures

Inflammatory bowel disease (IBD) is a common immune-related disease of the gastrointestinal tract that affects many people around the world. Extraintestinal manifestations of IBD have been frequently observed in recent years; one of these, periodontitis, has gained increasing attention. Periodontitis is a chronic inflammatory disease characterized by inflammation and destruction of periodontal tissues due to the disruption of host immune homeostasis. Clinical studies have revealed that periodontal inflammation is associated with IBD. However, the detailed heterogeneity of immune cells and their developmental relationships remain poorly understood at the single-cell level. In this study, we performed single-cell RNA (scRNA) sequencing to assess the transcriptome heterogeneity in periodontal tissues. We found the cellular composition and subclusters with specific gene expression profiles by uniform manifold approximation and projection. Pseudo-time analysis combined with gene enrichment analysis was performed to reveal cell states and key pathways. Ligand-receptor pairs revealed cell-cell communication among the immune cell types in periodontal tissues. Based on our analysis, we identified an essential role for Tcr⁺ macrophage, Prdx1⁺ neutrophil, and Mif⁺ T subpopulations with proinflammatory phenotype infiltration. Moreover, we examined the heterogeneity of monocytic cells and B cells. Collectively, the mapping of scRNA revealed the complex cellular landscape of oral mucosa immune cells and highlighted these immune cells as a previously unrecognized factor that may aggravate inflammation. Our analysis proves that periodontitis could exacerbate colitis and provides novel ideas for controlling and preventing IBD exacerbations.

Regulation of the Host Immune Microenvironment in Periodontitis and Periodontal Bone Remodeling

The periodontal immune microenvironment is a delicate regulatory system that involves a variety of host immune cells including neutrophils, macrophages, T cells, dendritic cells and mesenchymal stem cells. The dysfunction or overactivation of any kind of local cells, and eventually the imbalance of the entire molecular regulatory network, leads to periodontal inflammation and tissue destruction. In this review, the basic characteristics of various host cells in the periodontal immune microenvironment and the regulatory network mechanism of host cells involved in the pathogenesis of periodontitis and periodontal bone remodeling are summarized, with emphasis on the immune regulatory network that regulates the periodontal microenvironment and maintains a dynamic balance. Future strategies for the clinical treatment of periodontitis and periodontal tissue regeneration need to develop new targeted synergistic drugs and/or novel technologies to clarify the regulatory mechanism of the local microenvironment. This review aims to provide clues and a theoretical basis for future research in this field.

M2 macrophages with inflammation tropism facilitate cementoblast mineralization

BACKGROUND

Cementum regeneration was regarded as the critical goal for periodontal regeneration, and M2 macrophage-based therapy was expected to be a promising strategy. However, little is known about the effects of M2 macrophages on cementoblast mineralization and tropism, especially under inflammation. Here we investigated for the first time the crosstalk between M2 macrophages and Porphyromonas gingivalis (Pg)-stimulated cementoblasts.

METHODS

M2 macrophages were induced with interleukin (IL)-4, and identified. CC-chemokine ligand 2 (CCL2) expression and secretion of inflammatory cementoblasts were detected by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), western blotting (WB), immunohistochemistry for apical periodontitis (AP) mice, and by enzyme-linked immunosorbent assay. Crystal violet staining was used to observe macrophage migration. Conditional medium (CM) and transwell coculture methods were applied to evaluate the effects of M2 macrophages on cementum mineralization with or without Pg, and to explore the mechanism. Mineralization-related markers and pathway-related proteins were measured by RT-qPCR and WB.

RESULTS

M2 macrophages were identified successfully. We found an increase of CCL2 in cementoblasts and their supernatant. Also, higher CCL2 in cementoblasts was observed in the AP model. Superior recruitment of M2 macrophages to supernatant from Pg-stimulated cementoblasts or CCL2-containing medium was verified. Moreover, CM2 and Trans-M2 showed better mineralization-accelerating and rescuing effects when compared to their controls, and application of p38 inhibitor partially blocked the promotion.

CONCLUSIONS

Our study demonstrated the inflammation-targeting and mineralization-promoting effects of M2 macrophages on cementoblasts, which may provide evidence for M2 macrophage-based cementum regeneration.

Pathogenetic aspects of the development of psoriatic arthritis in people with generalized chronic periodontitis

The pathogenetic mechanisms of progression of chronic periodontitis and psoriatic arthritis have common components in immune and inflammatory responses.

The pathogenesis of chronic periodontitis involves interaction of microbial and immunological components. As a chronic immune-mediated inflammatory disease and a consequence of an infectious trigger that originally affects gingival soft tissue, periodontitis is typically characterized by periodontal destruction and damage to adjacent connective tissues. Neutrophils contribute to the development of periodontitis and participate in its progression by recruiting T helper 17 cells and stimulating synthesis of the receptor activator of the nuclear factor kappa-β ligand (RANKL), contributing to bone resorption.

Macrophages as producers of proinflammatory cytokines (interleukin (IL)-1β, IL-6, IL-22, IL-23, tumor necrosis factor (TNF)), free radicals, and matrix metalloproteinases contribute to the chronic course of the disease. Tissue destruction results in generation of reactive oxygen species by neutrophils, which, against the background of a decrease in the antioxidant potential, leads to development of oxidative stress. These processes together lead to tooth mobility, formation of periodontal pockets, and bone resorption.

The key factors in the formation of psoriatic arthritis against the background of periodontitis are overproduction of proinflammatory cytokines in target tissues (skin, joints, gingival microflora) and development of an excessive systemic immune response to the microbiota inhabiting the epithelial and periodontal tissues. A statistically confirmed correlation of the progression of periodontal destruction with the presence of psoriatic arthritis proves the significance of the effects of inflammation as a background for the progression of a comorbidity. Increased IL-17 synthesis plays a crucial role in the development of immune responses of pathological bone remodeling and bone resorption in periodontitis and psoriatic arthritis.