Estimation of Toll-like receptor 9 in gingival tissues of patients with chronic periodontitis with or without hyperlipidemia and its association with the presence of Porphyromonas gingivalis

Impact of periodontitis on circulating cell-free DNA levels as a measure of cardiovascular disease

OBJECTIVES

The present study aims to assess the serum circulating cell-free (cfDNA) concentrations in patients with periodontitis and cardiovascular disease (CVD) and to evaluate the impact of periodontitis on circulating cfDNA levels and the confounding factors that might mediated the possible relationship.

MATERIALS AND METHODS

Healthy controls (n=30) and patients with CVD (n=31), periodontitis (n=31), and periodontitis + CVD (n=30) were enrolled in the present study. All subjects underwent regular periodontal examination and blood sampling and cfDNA evaluation. The analysis of the plasma cfDNA concentrations was performed using a dsDNA Assay Kit.

RESULTS

In comparison with healthy controls and CVD patients, periodontitis and periodontitis+CVD exhibited significantly higher expression of circulating cfDNA (p<0.05). There was a positive correlation among plasma cfDNA and clinical attachment loss (CAL) (p=0.019), high sensitivity C-reactive protein (hs-CRP) (p=0.027), and periodontal inflamed surface area (PISA) (p=0.003). Furthermore, the multivariate regression analysis evidenced that PISA (p<0.001), hs-CRP (p=0.014), and full-mouth bleeding score (FMBS) (p=0.004) were significant predictors of circulating cfDNA concentrations.

CONCLUSIONS

The results of the study highlighted that the periodontitis and periodontitis + CVD group showed higher circulating cfDNA expression in comparison with healthy controls and CVD patients. Moreover, the extent of periodontitis was correlated with the increased cfDNA levels and represented a significant predictor of the increased circulating cfDNA concentrations.

CLINICAL RELEVANCE

Unbalanced circulating cfDNA concentrations have been indicated to represent a possible risk of CVD and endothelial dysfunction. Periodontitis and periodontitis + CVD patients showed higher circulating cfDNA expression; moreover, the extent of periodontitis significantly predicted higher circulating cfDNA concentrations, suggesting the potential increased risk of developing CVD in periodontitis patients.

New Trends in the Impact of Periodontal Treatment on Early Cardiovascular Diseases Outcomes: Insights and Future Perspectives

Cardiovascular diseases represent the primary worldwide cause of mortality, and periodontitis is the main cause of tooth loss. The incidence of atherosclerotic disease has been reported to be higher in individuals affected by periodontitis than in individuals without, regardless of many common risk factors are present. Various pathogenetic models have been presented to clarify the close correlation between these two diseases. First, periodontal bacteria and their toxins can enter the circulation both during dental procedures and normal activities such as eating and teeth brushing. Periodontal bacteria may indirectly contribute to coronary artery disease (e.g., by causing immunological reactions) or directly by damaging coronary arteries. Periodontal treatment significantly reduces periodontal pathogens such as Porphyromonas gingivalis (Pg) or Actinobacillus actinomycetemcomitans (Aa) in deep periodontal pockets. Moreover, periodontal treatment may lower blood inflammatory mediators, enhance the lipid profile, and cause favourable changes in various surrogate markers for cardiovascular disease. The way in which oral bacteremia and periodontal inflammation cause atherosclerosis is still unclear and needs further studies. The real effectiveness of periodontal treatment in preventing cardiovascular events is a topic of current interest. In this regard, this review article explores new insights and provides an indication of future directions on the function of periodontal inflammation and oral bacteria in the incidence and progression of atherosclerosis and cardiovascular diseases, with the main focus on assessing the impact of periodontal treatment on cardiovascular disease outcome biomarkers.

Impact of Circulating Cell-Free DNA (cfDNA) as a Biomarker of the Development and Evolution of Periodontitis

In the last few decades, circulating cell-free DNA (cfDNA) has been shown to have an important role in cell apoptosis or necrosis, including in the development and evolution of several tumors and inflammatory diseases in humans. In this regard, periodontitis, a chronic inflammatory disease that can induce the destruction of supporting components of the teeth, could represent a chronic inflammatory stimulus linked to a various range of systemic inflammatory diseases. Recently, a possible correlation between periodontal disease and cfDNA has been shown, representing new important diagnostic-therapeutic perspectives. During the development of periodontitis, cfDNA is released in biological fluids such as blood, saliva, urine and other body fluids and represents an important index of inflammation. Due to the possibility of withdrawing some of these liquids in a non-invasive way, cfDNA could be used as a possible biomarker for periodontal disease. In addition, discovering a proportional relationship between cfDNA levels and the severity of periodontitis, expressed through the disease extent, could open the prospect of using cfDNA as a possible therapeutic target. The aim of this article is to report what researchers have discovered in recent years about circulating cfDNA in the development, evolution and therapy of periodontitis. The analyzed literature review shows that cfDNA has considerable potential as a diagnostic, therapeutic biomarker and therapeutic target in periodontal disease; however, further studies are needed for cfDNA to be used in clinical practice.

The potential role of cfDNA-related innate immune responses in postoperative bone loss after alveolar bone grafting

The purpose of treating alveolar bone cleft is to restore a normal maxilla structure. Multiple factors have been identified that can affect the success of alveolar bone grafting. However, with consistent treatment modifications, the surgical outcomes have been improved, but alveolar bone loss still exists. Thus, a new aspect should be found to solve this problem. As alveolar bone belongs to the periodontal tissues, the mechanism of the alveolar bone loss after bone grafting in patients with alveolar bone cleft may be similar to the development of alveolar bone loss in periodontitis. Cell-free DNA (cfDNA) has been demonstrated as a key promoter of alveolar bone loss during periodontal inflammation. We hypothesized that cfDNA-related innate immune responses could be a major inducement for postoperative bone loss after alveolar bone grafting. In this perspective, we preliminarily proved the potential association between cfDNA, TLR9 pathway, and alveolar bone grafting operation, and it might verify that surgical trauma could accumulate cfDNA, which can further activate cellular TLR9 signaling.

Association between Porphyromonas Gingivalis and systemic diseases: Focus on T cells-mediated adaptive immunity

The association between periodontal disease and systemic disease has become a research hotspot. Porphyromonas gingivalis (P. gingivalis), a crucial periodontal pathogen, affects the development of systemic diseases. The pathogenicity of P. gingivalis is largely linked to interference with the host's immunity. This review aims to discover the role of P. gingivalis in the modulation of the host's adaptive immune system through a large number of virulence factors and the manipulation of cellular immunological responses (mainly mediated by T cells). These factors may affect the cause of large numbers of systemic diseases, such as atherosclerosis, hypertension, adverse pregnancy outcomes, inflammatory bowel disease, diabetes mellitus, non-alcoholic fatty liver disease, rheumatoid arthritis, and Alzheimer's disease. The point of view of adaptive immunity may provide a new idea for treating periodontitis and related systemic diseases.

Nanoparticulate cell-free DNA scavenger for treating inflammatory bone loss in periodontitis

Periodontitis is a common type of inflammatory bone loss and a risk factor for systemic diseases. The pathogenesis of periodontitis involves inflammatory dysregulation, which represents a target for new therapeutic strategies to treat periodontitis. After establishing the correlation of cell-free DNA (cfDNA) level with periodontitis in patient samples, we test the hypothesis that the cfDNA-scavenging approach will benefit periodontitis treatment. We create a nanoparticulate cfDNA scavenger specific for periodontitis by coating selenium-doped hydroxyapatite nanoparticles (SeHANs) with cationic polyamidoamine dendrimers (PAMAM-G3), namely G3@SeHANs, and compare the activities of G3@SeHANs with those of soluble PAMAM-G3 polymer. Both G3@SeHANs and PAMAM-G3 inhibit periodontitis-related proinflammation in vitro by scavenging cfDNA and alleviate inflammatory bone loss in a mouse model of ligature-induced periodontitis. G3@SeHANs also regulate the mononuclear phagocyte system in a periodontitis environment, promoting the M2 over the M1 macrophage phenotype. G3@SeHANs show greater therapeutic effects than PAMAM-G3 in reducing proinflammation and alveolar bone loss in vivo. Our findings demonstrate the importance of cfDNA in periodontitis and the potential for using hydroxyapatite-based nanoparticulate cfDNA scavengers to ameliorate periodontitis.

PAMPs and DAMPs as the Bridge Between Periodontitis and Atherosclerosis: The Potential Therapeutic Targets

Atherosclerosis is a chronic artery disease characterized by plaque formation and vascular inflammation, eventually leading to myocardial infarction and stroke. Innate immunity plays an irreplaceable role in the vascular inflammatory response triggered by chronic infection. Periodontitis is a common chronic disorder that involves oral microbe-related inflammatory bone loss and local destruction of the periodontal ligament and is a risk factor for atherosclerosis. Periodontal pathogens contain numerous pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide, CpG DNA, and Peptidoglycan, that initiate the inflammatory response of the innate immunity depending on the recognition of pattern-recognition receptors (PRRs) of host cells. The immune-inflammatory response and destruction of the periodontal tissue will produce a large number of damage-associated molecular patterns (DAMPs) such as neutrophil extracellular traps (NETs), high mobility group box 1 (HMGB1), alarmins (S100 protein), and which can further affect the progression of atherosclerosis. Molecular patterns have recently become the therapeutic targets for inflammatory disease, including blocking the interaction between molecular patterns and PRRs and controlling the related signal transduction pathway. This review summarized the research progress of some representative PAMPs and DAMPs as the molecular pathological mechanism bridging periodontitis and atherosclerosis. We also discussed possible ways to prevent serious cardiovascular events in patients with periodontitis and atherosclerosis by targeting molecular patterns.

Research on Autophagy of Gingiva Epithelial Cell Induced by Porphyromonas Gingivalis Regulated by Long Non-Coding RNA Transforming Growth Factor Beta-2 Overlapping Transcript 1 (LncRNA TGFB2-OT1)

Our study analyzes lncRNA TGFB2-OT1’s effect on autophagy and migration of gingiva epithelial cells and porphyromonas gingivalis. The expression of TGFB2-OT1 and TIMP2 in GEC cells was detected by QRT-PCR. Cell proliferation and colon formation was assessed by MTT method and colony forming assay. The relation between TGFB2-OT1 and TIMP2 was confirmed luciferase assay. The autophagy, apoptosis rate and period distribution was detected by flow cytometry along with analysis of porphyromonas gingivalis of GEC cells. TGFB2-OT1 was upregulated significantly as shown by IncRNA array. TGFB2-OT1 overexpression in GEC cells improved cell proliferation and migration, enhanced the sensibility of gingiva epithelial cell on the porphyromonas gingivalis and increased autophagy. The GEC cells were blocked at G2/M period. The TIMP2 was a direct target of TGFB2-OT1. In conclusion, TIMP2 participates in the up-regulation of MMP10 induced by TGFB2-OT1. The lncRNA TGFB2-OT1 maybe be a potential biomarker to assess the autophagy of gingiva epithelial cell.

Porphyromonas gingivalis and rheumatoid arthritis

PURPOSE OF REVIEW

To explore the pathogenic association between periodontal disease and rheumatoid arthritis focusing on the role of Porphyromonas gingivalis.

RECENT FINDINGS

In the last decades our knowledge about the pathogenesis of rheumatoid arthritis substantially changed. Several evidences demonstrated that the initial production of autoantibodies is not localized in the joint, rather in other immunological-active sites. A central role seems to be played by periodontal disease, in particular because of the ability of P. gingivalis to induce citrullination, the posttranslational modification leading to the production of anticitrullinated protein/peptide antibodies, the most sensitive and specific rheumatoid arthritis biomarker.

SUMMARY

The pathogenic role of P. gingivalis has been demonstrated in mouse models in which arthritis was either triggered or worsened in infected animals. P. gingivalis showed its detrimental role not only by inducing citrullination but also by means of other key mechanisms including induction of NETosis, osteoclastogenesis, and Th17 proinflammatory response leading to bone damage and systemic inflammation.