Molecular analysis shows the presence of periodontal bacterial DNA in atherosclerotic plaques from patients with coronary artery disease

Mechanism and functional verification of genes by virulence factors of P. gingivalis in ferroptosis

OBJECTIVE

Porphyromonas gingivalis (P. gingivalis) is a key etiological agent in periodontitis and functions as a facultative intracellular microorganism and involves many virulence factors. These virulence factors participate in multiple intracellular processes, like ferroptosis, the mechanistic underpinnings remain to be elucidated. Aim of this study was to investigate the effects of virulence factors on the host cells.

DESIGN

Human umbilical vein endothelial cells (HUVECs) were treated with 4% paraformaldehyde-fixed P. gingivalis, and subsequent alterations in gene expression were profiled via RNA-seq. Further, the molecules associated with ferroptosis were quantitatively analyzed using qRT-PCR and Western blot.

RESULTS

A total of 1125 differentially expressed genes (DEGs) were identified, encompassing 225 upregulated and 900 downregulated. Ferroptosis was conspicuously represented in the kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis, with notable upregulation of Heme oxygenase 1 (HMOX1), Ferritin light chain (FTL), and Solute carrier family 3 member 2 (SLC3A2) and downregulation of Scavenger receptor class A member 5 (SCARA5) and glutaminase (GLS). Random selection of DEGs for validation through qRT-PCR corroborated the RNA-Seq data (R2 = 0.93). Kelch like ECH associated protein 1 (Keap1) protein expression decreased after 4 and 8 h, while NFE2 like bZIP transcription factor 2 (Nrf2) and HMOX1 were elevated, with significant nuclear translocation of Nrf2.

CONCLUSIONS

The virulence factors of P. gingivalis may potentially instigating ferroptosis through activation of the Keap1-Nrf2-HMOX1 signaling cascade, in conjunction with modulating the expression of other ferroptosis-associated elements. Further research is necessary to achieve a thorough comprehension of these complex molecular interactions.

Metagenomic Analysis to Uncover the Subgingival and Atherosclerotic Plaque Microbiota in Patients with Coronary Artery Disease

The role of periodontal pathogens in the initiation and progression of atherosclerosis has been extensively researched, yet a precise causal mechanism has not been established. The subgingival microbiota may be a source of dissemination and may contribute to the development of atherosclerosis; hence this study attempted to characterize and compare the subgingival and atherosclerotic plaques. Plaque samples were subjected to 16S rRNA-based metagenomics to study microbiota associated with subgingival and atherosclerotic plaques collected from patients with coronary artery disease. The PCoA analysis showed that the microbiomes of subgingival plaques were highly scattered and showed a diverse microbial composition, unlike the atherosclerotic plaques that did not show evident variability in the microbial composition and formed a close distinct group. The abundance of various genera in the subgingival plaques revealed Fusobacterium (11%), Acinetobacter (13%), Veillonella (9%), and Prevotella (11%) among the top ten genera. The atherosclerotic plaques contained Acinetobacter (39%), Chryseobacterium (9%), Rhizobium (5%), and Staphylococcus (4%). All the patients examined in this study had either generalized or localized periodontitis with varying degrees of severity. The community microbiota analysis revealed that 22 bacterial genera were shared between two different plaques, with Acinetobacter being dominant. Based on the Human Oral Microbiome Database, 55% of the shared microbiota in this study have been listed as periodontal microbiota, with some of them found in increased proportions in patients with periodontitis suggesting the translocation of bacteria from the periodontal pockets into the circulation. This study provides valuable insights into the possible relationship between periodontal pathogens and atherosclerotic cardiovascular disease.

Graphical Abstract

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 Correlation between Periodontal Parameters and Cell-Free DNA in the Gingival Crevicular Fluid, Saliva, and Plasma in Chinese Patients: A Cross-Sectional Study

Purpose: To investigate the correlation between periodontal parameters and cell-free DNA (cfDNA) concentrations in gingival crevicular fluid (GCF), saliva, and plasma. Methods: Full mouth periodontal parameters, including probing depth (PD), bleeding on probing (BOP), and plaque index (PI) were recorded from 25 healthy volunteers, 31 patients with untreated gingivitis, and 25 patients with untreated periodontitis. GCF, saliva, and plasma samples were collected from all subjects. Extraction and quantification assays were undertaken to determine cfDNA concentrations of each sample. Results: GCF and salivary cfDNA levels were increased with aggravation of periodontal inflammation (GCF p < 0.0001; saliva p < 0.001). Plasma cfDNA concentrations in patients with periodontitis were significantly higher than those in healthy volunteers and patients with gingivitis. GCF and salivary cfDNA were positively correlated with mean PD, max PD, BOP, and mean PI (p < 0.0001), whereas plasma cfDNA was not correlated with BOP (p = 0.099). Conclusion: GCF, saliva, and plasma concentrations of cfDNA were significantly elevated in patients with periodontal disease. There were also positive correlations between cfDNA levels in GCF and saliva and periodontal parameters.

Probiotics Bring New Hope for Atherosclerosis Prevention and Treatment

Cardiovascular disease is the leading cause of human mortality and morbidity worldwide. Atherosclerosis (AS) is the underlying pathological responsible in most acute and severe cardiovascular diseases including myocardial infarction and stroke. However, current drugs applied to the treatment of AS are not clinically effective, and there is a large residual risk of cardiovascular disease and multiple side effects. Increasing evidence supports a close relationship between microorganisms and the incidence of AS. Recent data have shown that probiotics can improve multiple key factors involved in the development and progression of AS, including cholesterol metabolism imbalance, endothelial dysfunction, proinflammatory factor production, macrophage polarization, intestinal flora disturbance, and infection with pathogenic microorganisms, and therefore probiotics have attracted great interest as a novel potential “medicine”. This review is aimed at summarizing the effects of probiotics on various influencing factors, and providing valuable insights in the search for early prevention and potential therapeutic strategies for AS.

The impact of periodontitis on vascular endothelial dysfunction

Periodontitis, an oral inflammatory disease, originates from periodontal microbiota dysbiosis which is associated with the dysregulation of host immunoinflammatory response. This chronic infection is not only harmful to oral health but is also a risk factor for the onset and progress of various vascular diseases, such as hypertension, atherosclerosis, and coronary arterial disease. Vascular endothelial dysfunction is the initial key pathological feature of vascular diseases. Clarifying the association between periodontitis and vascular endothelial dysfunction is undoubtedly a key breakthrough for understanding the potential relationship between periodontitis and vascular diseases. However, there is currently a lack of an updated review of their relationship. Therefore, we aim to focus on the implications of periodontitis in vascular endothelial dysfunction in this review.

Fast, Simple, and Highly Specific Molecular Detection of Porphyromonas gingivalis Using Isothermal Amplification and Lateral Flow Strip Methods

Porphyromonas gingivalis is an important oral pathogen that causes periodontal disease and is difficult to culture under conventional conditions. Therefore, a reliable technique for detecting this pathogenic bacterium is required. Here, isothermal recombinase polymerase amplification (RPA), a new nucleic acid amplification method, was combined with a visualization method based on nanoparticle-based lateral flow strips (LFS) for the rapid detection of P. gingivalis. The species-specific 16S rRNA sequence of P. gingivalis was used as the target for RPA, and a set of specific primer–probe combinations were designed and screened to amplify the target sequences. As a thermostatic amplification method, the RPA reaction, under optimized conditions, takes only 30 min to complete at a constant temperature (37°C). The amplification reaction products can be detected visually by LFS without any need for special equipment. The RPA-LFS method established for the detection of P. gingivalis was shown to be highly specific in distinguishing P. gingivalis from other pathogenic organisms by using 20 clinical isolates of P. gingivalis and 23 common pathogenic microorganisms. Susceptibility measurements and probit regression analysis were performed with gradient dilutions of P. gingivalis genomic DNA. The method was obtained to be highly sensitive, with a detection limit of 9.27 CFU per reaction at 95% probability. By analyzing the gingival sulcus fluid specimens from 130 patients with chronic periodontitis, the results showed that the RPA-LFS method detected 118 positive cases and 12 negative cases of P. gingivalis, and the results obtained were consistent with those of a conventional PCR assay. The RPA–LFS method is an efficient, rapid, and convenient diagnostic method that simplifies the tedious process of detecting P. gingivalis.

Unexpected Relationships: Periodontal Diseases: Atherosclerosis-Plaque Destabilization? From the Teeth to a Coronary Event

Simple Summary

Periodontal disease and atherosclerotic cardiovascular disease are very common around the world. Coronary artery disease is the leading cause of death. The main factor involved in the pathogenesis of atherosclerosis is inflammation. Therefore, a number of studies have indicated that periodontal disease (causes chronic inflammation) is a risk factor for the progression of atherosclerosis. The presence of periodontal pathogens has been found in human atherosclerotic plaques. A number of pathomechanisms have been demonstrated, thanks to which periodontal pathogens, especially Porphyromonas gingivalis, can directly increase the progression of atherosclerosis and the risk of cardiovascular disease. Observational studies found that patients with periodontal disease were at higher risk of developing atherosclerotic cardiovascular disease. Moreover, periodontal treatment leads to a reduction in cardiovascular risk therefore taking care of oral hygiene should be an important cardiovascular disease preventive measure.

Abstract

Atherosclerotic cardiovascular disease (ASCVD) and periodontal disease (PD) are global health problems. High frequency of ASCVD is associated with the spread of many risk factors, including poor diet, sedentary lifestyle, diabetes, hyperlipidemia, obesity, smoking, hypertension, chronic kidney disease, hypertension, hyperhomocysteinemia, hyperuricemia, excessive stress, virus infection, genetic predisposition, etc. The pathogenesis of ASCVD is complex, while inflammation plays an important role. PD is a chronic, multifactorial inflammatory disease caused by dysbiosis of the oral microbiota, causing the progressive destruction of the bone and periodontal tissues surrounding the teeth. The main etiological factor of PD is the bacteria, which are capable of activating the immune response of the host inducing an inflammatory response. PD is associated with a mixed microbiota, with the evident predominance of anaerobic bacteria and microaerophilic. The “red complex” is an aggregate of three oral bacteria: Tannerella forsythia Treponema denticola and Porphyromonas gingivalis responsible for severe clinical manifestation of PD. ASCVD and PD share a number of risk factors, and it is difficult to establish a causal relationship between these diseases. The influence of PD on ASCVD should be treated as a factor increasing the risk of atherosclerotic plaque destabilization and cardiovascular events. The results of observational studies indicate that PD significantly increases the risk of ASCVD. In interventional studies, PD treatment was found to have a beneficial effect in the prevention and control of ASCVD. This comprehensive review summarizes the current knowledge of the relationship between PD and ASCVD.