Roles of trained immunity in the pathogenesis of periodontitis

Genipin attenuates oxidative damage in periodontal tissues by alleviating mitochondrial dysfunction and abnormal glucose uptake through inhibition of UCP2

Introduction

Periodontitis is a chronic inflammatory disease closely associated with mitochondrial dysfunction. Uncoupling protein 2 (UCP2), located in the inner membrane of mitochondria, reduces mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) synthesis by promoting proton leakage across the membrane. This leads to decreased energy metabolism efficiency, impairing cellular glucose uptake, and disrupting intracellular energy balance. Genipin (GP), a recognized UCP2 inhibitor, exhibits anti-inflammatory and antioxidant properties. This study aimed to investigate the specific role of GP in periodontal tissue redox signaling and the potential mechanism of UCP2 in the development of periodontitis.

Methods

In this study, we constructed a model of H2O2-induced oxidative stress in human periodontal ligament cells (hPDLCs). In vivo, a rat periodontitis model was established to evaluate the effects and mechanisms of GP in alleviating oxidative damage in periodontal tissues and cells.

Results

Cell experiments showed that GP effectively alleviated H2O2-induced mitochondrial dysfunction and oxidative damage in hPDLCs by inhibiting UCP2 expression and function, restoring cell viability, and reducing cell apoptosis. Additionally, GP intervention increased the expression of glucose transporter 4 (GLUT4), thereby promoting cellular glucose uptake. The results of animal experiments demonstrated that GP intervention reduced alveolar bone resorption and periodontal tissue destruction in rats with periodontitis, inhibited osteoclast differentiation, improved mitochondrial dysfunction in periodontal tissue, promoted GLUT4 expression, and reduced oxidative stress levels and cell apoptosis.

Discussion

GP regulates oxidative damage in periodontal tissues by maintaining mitochondrial homeostasis, promoting glucose transporter expression, and enhancing glucose uptake, with UCP2 playing a central role.

Bioinformatics analysis of shared biomarkers and immune pathways of preeclampsia and periodontitis

BACKGROUND

Epidemiological evidence indicates that preeclampsia (PE) is associated with comorbidities such as periodontitis (PD). However, the underlying mechanism remains unclear. To enhance our understanding of their co-pathogenesis, this research investigated the shared biomarkers and pathological mechanisms.

METHODS

We systematically retrieved transcriptomic datasets from the Gene Expression Omnibus database. These datasets encompass a comparative analysis of the periodontium with and without PD and of the placenta with and without PE. Differentially Expressed Genes Analysis and Weighted Gene Go-expression Network Analysis (WGCNA) were used to identify the key crosstalk genes in patients with PD and PE. The functional characterisation of these genes was performed using enrichment analysis. Protein-protein interaction networks and machine learning methods were leveraged to identify shared hub genes. The XG-Boost algorithm was applied to construct diagnostic models to gain insight into disease aetiology. The identified genes were validated by single-cell RNA sequencing to ensure their robustness and biological relevance.

RESULTS

A total of 55 key crosstalk genes were identified, which were primarily enriched in immune-related pathways by using limma and WGCNA. Among them, twenty-four shared hub genes were identified using protein-protein interaction analysis and machine learning methods. The diagnostic model constructed using immune-related genes outperformed the other two models (area under the receiver operating characteristic curve [ROC] = 0.7786 and 0.7454 for PE and PD, respectively). Pathways involving these genes were mapped using the Kyoto Encyclopedia of Genes and Genomes analysis. In addition, single-cell RNA sequencing analysis showed that the expression of BIN2, LYN, PIK3AP1, and NEDD9 in neutrophils was significantly downregulated, and LYN in fibroblasts and endothelial cells was consistently upregulated.

CONCLUSIONS

Shared hub genes and immunologic pathways were identified in PE and PD, characterised by crosstalk between BIN2, LYN, NEDD9, and PIK3AP1, suggesting the pathogenesis of PE and PD, which could pave the way for the development of effective diagnostic, treatment, and management strategies.

Innate immune training of osteoclastogenesis promotes inflammatory bone loss in mice

We previously demonstrated that long-term trained immunity (TRIM) involves adaptations that imprint innate immune memory in long-lived myelopoiesis precursors and their progeny, monocytes/macrophages and neutrophils, which thereby acquire enhanced responsiveness to future challenges. Here, we show that a distinct component of myeloid biology, osteoclastogenesis, can also undergo innate immune training. Indeed, β-glucan-induced TRIM was associated with an increased osteoclastogenesis bias in the bone marrow and an expansion of monocytes/osteoclast progenitors in the periphery, resulting in aggravated severity of experimental periodontitis and arthritis. In the setting of trained inflammatory osteoclastogenesis, we observed transcriptomic rewiring in synovial myeloid cells of arthritic mice, featuring prominent upregulation of the transcription factor melanogenesis-associated transcription factor (MITF). Adoptive transfer of splenic monocytes from β-glucan-trained mice to naive recipients exacerbated arthritis in the latter in a strictly MITF-dependent manner. Our findings establish trained osteoclastogenesis as a maladaptive component of TRIM and potentially provide therapeutic targets in inflammatory bone loss disorders.

Quercetin through miR-147-5p/Clip3 axis reducing Th17 cell differentiation to alleviate periodontitis

Background

Quercetin (QU) plays an important role in treating periodontitis; however, the mechanism through which microRNAs regulate Th17 cell differentiation has not been determined.

Methods

QU was administered intragastrically to periodontitis rats once a day for one month. The morphology of alveolar bone was observed by micro-CT, gingival tissue structure was observed by HE staining, IL-6, TNF-α, IL-17A, RORγt, FOXP3 and IL-10 were detected by immunohistochemical staining, and Th17 and Treg cells in the peripheral blood were detected by flow cytometry. CD4+T cells were induced to differentiate into Th17 cells in vitro. Cell viability was determined by CCK8, and IL-17A and RORγt were detected by qPCR. Th17 cells were detected by flow cytometry, microRNA sequencing and bioinformatics analysis were used to screen key microRNAs, the phenotypic changes of Th17 cells were observed after overexpressed microRNAs via mimics. TargetScan database, in situ hybridization, and dual-luciferase reporter experiment were used to predict and prove target genes of microRNAs. The phenotype of Th17 cells was observed after overexpression of microRNA and target gene.

Results

Compared with periodontitis group, the distance from cementoenamel junction(CEJ) to alveolar bone(AB) was decreased, the structure of gingival papilla was improved, IL-6, TNF-α, IL-17, and RORγt were downregulated, FOXP3 and IL-10 were upregulated, the proportion of Th17 decreased and Treg increased in peripheral blood after QU treatment. Compared with Th17 cell group, mRNA levels of IL-17A and RORγt were decreased, and proportion of Th17 cells was significantly lower in the coculture group. MiR-147-5p was low in control group, upregulated in Th17 cell group, and downregulated after QU intervention, it's eight bases were inversely related to 3'UTR of Clip3, miR-147-5p with Clip3 were co-located in cells of periodontal tissue. Compared with those in Th17-mimicsNC + QU cells, the mRNA levels of RORγt and IL-17A upregulated, and proportion of Th17 cells increased in Th17-miR-147-5p + QU cells. The miR-147-5p mimics inhibited the luciferase activity of the WT Clip3 3'UTR but had no effect on the Mut Clip3 3'UTR. Clip3 was significantly downregulated after the overexpression of miR-147-5p. Mimics transfected with miR-147-5p reversed the decrease in the proportion of Th17 cells induced by QU, while the overexpression of Clip3 antagonized the effect of miR-147-5p and further reduced the proportion of Th17 cells. Moreover, the overexpression of miR-147-5p reversed the decreases in the mRNA levels of IL-17 and RORγt induced by QU treatment, while pcDNA3.1 Clip3 treatment further decreased the mRNA levels of IL-17 and RORγt.

Conclusion

QU reducing inflammatory response and promoting alveolar bone injury and repair, which closely relative to inhibit the differentiation of CD4+T cells into Th17 cells by downregulating miR-147-5p to promote the activation of Clip3.

D-mannose alleviates chronic periodontitis in rats by regulating the functions of neutrophils

BACKGROUND

Periodontitis is a chronic inflammatory disease characterized by the destruction of the components of the periodontium. It significantly impacts oral health and has been linked to systemic conditions like cardiovascular disease and diabetes. The critical role of neutrophils in the occurrence and development of chronic periodontitis has been paid increasing attention. The study aimed to explore the protective effects of D-mannose on chronic periodontitis and determine whether its underlying mechanisms is related to neutrophils.

METHODS

To explore the protective effects of D-mannose on chronic periodontitis, the eight-week-old Sprague Dawley rat model of lipopolysaccharide (LPS)-induced periodontitis was established, followed by D-mannose treatment by oral gavage. To evaluate the protective effects of D-mannose against periodontal bone loss, methylene blue staining, hematoxylin and eosin (H&E) staining, and micro-CT scanning were utilized. Then, immunofluorescence (IF), Western Blot, and RT-PCR were applied to assess the expression levels of pro-inflammatory cytokines (IL-1β, IL-6, and IL-17), anti-inflammatory cytokine (IL-10), tumor necrosis factor-alpha (TNF-α), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), ten-eleven translocation 2 (TET2), and key glycolytic enzymes (HK1, HK2, PFKFB3), and to examine D-mannose's impact on the recruitment and activation of neutrophils in the gingiva. Additionally, neutrophils isolated from the peripheral blood of healthy rats were treated with LPS and D-mannose, and changes in the expression levels of myeloperoxidase (MPO), IL-1β, IL-6, IL-17, IL-10, and TET2 were observed via IF.

RESULTS

In vivo, D-mannose inhibited LPS-induced alveolar bone resorption in rats. After D-mannose treatment, the expression levels of IL-17 (p<0.01) and TET2 (p<0.01) were suppressed by IF, and the expression levels of IL-1β (p<0.05), IL-17 (p<0.05) and TET2 (p<0.01) were downregulated by WB. The results of qPCR showed that D-mannose reduced the expression levels of IL-1β (p<0.05), IL-6 (p<0.01), IL-17 (p<0.01), TNF-α (p<0.01), G-CSF (p<0.01), GM-CSF (p<0.01), TET2 (p<0.01), HK1 (p<0.01), HK2 (p<0.01), and PFKFB3 (p<0.01). D-mannose also inhibited the recruitment and activation of neutrophils in LPS-treated rat gingival tissues. In vitro, the results of IF showed that D-mannose inhibited the activation of neutrophils stimulated by LPS, downregulated the expression of IL-1β (p < 0.05), IL-6, IL-17 (p < 0.01), and TET2 (p < 0.01), and upregulated the expression of IL-10 (p < 0.01).

CONCLUSIONS

D-mannose can alleviate chronic periodontitis in rats by regulating the functions of neutrophils, potentially associated with the expression of TET2 and glycolysis, providing new insights into the potential application of D-mannose to chronic periodontitis.

Cytokines in gingivitis and periodontitis: from pathogenesis to therapeutic targets

Chronic inflammatory processes in the oral mucosa and periodontitis are common disorders caused by microflora and microbial biofilms. These factors activate both the innate and adaptive immune systems, leading to the production of pro-inflammatory cytokines. Cytokines are known to play a crucial role in the pathogenesis of gingivitis and periodontitis and have been proposed as biomarkers for diagnosis and follow-up of these diseases. They can activate immune and stromal cells, leading to local inflammation and tissue damage. This damage can include destruction of the periodontal ligaments, gingiva, and alveolar bone. Studies have reported increased local levels of pro-inflammatory cytokines, such as interleukin-1beta (IL-1beta), tumor necrosis factor (TNF), IL-6, IL-17, and IL-23, in patients with periodontitis. In experimental models of periodontitis, TNF and the IL-23/IL-17 axis play a pivotal role in disease pathogenesis. Inactivation of these pro-inflammatory pathways through neutralizing antibodies, genetic engineering or IL-10 function has been demonstrated to reduce disease activity. This review discusses the role of cytokines in gingivitis and periodontitis, with particular emphasis on their role in mediating inflammation and tissue destruction. It also explores new therapeutic interventions that offer potential for research and clinical therapy in these chronic inflammatory diseases.

Increased of IL-18 levels are associated with periodontitis: a systematic review and meta-analysis

BACKGROUND

The presence of a polymicrobial dysbiotic film in direct and constant contact with periodontal tissues initiates the host immune response. Interleukin 18 (IL-18) triggers up-regulates the production of other proinflammatory cytokines (TNF-α, IL-1β, IL-6), creating a vicious cycle that expands the inflammatory and destructive process in the periodontal tissue. A systematic review and meta-analysis was carried out with the main propose to investigate IL-18 expression in different biological samples from subjects with chronic periodontitis.

METHODS

The protocol followed PRISMA guidelines and was registered in Open Science Framework (OSF): https://doi.org/10.17605/OSF.IO/BS9GM . A digital search was conducted in the databases PubMed, ScienceDirect, Google Scholar, Web of Science and Dentistry & Oral Sciences Source databases were consulted from March 15th, 2005 to February 10th, 2023. Study quality was assessed using the JBI tool for cross-sectional studies and clinical trials. A meta-analysis was performed using a random/fixed effects model to evaluate the concentration of IL-18 in serum, plasma, saliva, gingival tissue and GCF of exposure group compared to control group.

RESULTS

The search strategy provided a total of 3,156 articles, of which 18 investigations met the inclusion criteria and 15 articles were quantitatively analyzed. The total number of patients studied was 1,275 (682 cases and 593 controls). The meta-analysis revealed significantly elevated IL-18 levels of serum, saliva and GCF of subjects with chronic periodontitis compared to healthy subjects (Serum: SMD = 62.73, 95%CI: 25.43-100.03, Z = 3.29, p = 0.001*; Saliva: SMD = 243.63, 95%CI: 8.68-478.59, Z = 2.03, p = 0.042*; GCF: SMD = 150.26, 95%CI: 56.86-243.66, Z = 3.15, p = 0.02*).

CONCLUSION

IL-18 levels in serum, saliva and GCF could have the potential to be used as complementary diagnostic tools to the clinical and radiographic parameters in subjects with periodontitis.

Matrix Metalloproteinases in the Periodontium-Vital in Tissue Turnover and Unfortunate in Periodontitis

The extracellular matrix (ECM) is a complex non-cellular three-dimensional macromolecular network present within all tissues and organs, forming the foundation on which cells sit, and composed of proteins (such as collagen), glycosaminoglycans, proteoglycans, minerals, and water. The ECM provides a fundamental framework for the cellular constituents of tissue and biochemical support to surrounding cells. The ECM is a highly dynamic structure that is constantly being remodeled. Matrix metalloproteinases (MMPs) are among the most important proteolytic enzymes of the ECM and are capable of degrading all ECM molecules. MMPs play a relevant role in physiological as well as pathological processes; MMPs participate in embryogenesis, morphogenesis, wound healing, and tissue remodeling, and therefore, their impaired activity may result in several problems. MMP activity is also associated with chronic inflammation, tissue breakdown, fibrosis, and cancer invasion and metastasis. The periodontium is a unique anatomical site, composed of a variety of connective tissues, created by the ECM. During periodontitis, a chronic inflammation affecting the periodontium, increased presence and activity of MMPs is observed, resulting in irreversible losses of periodontal tissues. MMP expression and activity may be controlled in various ways, one of which is the inhibition of their activity by an endogenous group of tissue inhibitors of metalloproteinases (TIMPs), as well as reversion-inducing cysteine-rich protein with Kazal motifs (RECK).