Invasion of human aortic endothelial cells by oral viridans group streptococci and induction of inflammatory cytokine production

Metagenomic Analysis of Bacterial Microflora in Dental and Atherosclerotic Plaques of Patients With Internal Carotid Artery Stenosis

Background

Internal carotid artery stenosis is primarily attributed to atherosclerosis in the carotid artery bifurcation. Previous studies have detected oral bacteria in atherosclerotic lesions, suggesting an association between oral bacteria and atherosclerosis. In this study, we compared the bacterial flora of the atherosclerotic plaque in the carotid artery and dental plaque of patients with internal carotid artery stenosis using 16S ribosomal RNA (16S rRNA) metagenomic sequencing.

Methods

Fifty-four patients who underwent internal carotid endarterectomy for internal carotid artery stenosis at the Showa University Hospital between April 2016 and February 2018 were included. Polymerase chain reaction targeting the 16S rRNA gene detected bacterial DNA in the carotid plaques of 11 cases, of which only 5 could be further analyzed. Thereafter, DNA extracted from the carotid and oral plaques of these 5 cases were analyzed using metagenomic sequencing targeting 16S rRNA. In addition, their general condition and oral conditions were evaluated. The patients were classified into symptomatic and asymptomatic groups based on the presence or absence of symptoms of transient ischemic attack, and their bacterial flora was evaluated.

Results

The results demonstrated that the microflora of carotid plaques (n = 5) contained bacterial species from 55 families and 78 genera. In addition, 86.5% of the bacteria detected in the carotid plaques were also detected in oral plaques. Cariogenic and periodontopathic bacteria accounted for 27.7% and 4.7% of the bacteria in the carotid plaques, respectively.

Conclusions

These results suggest that oral bacteria are directly or indirectly involved in the pathogenesis of atherosclerosis. More extensive studies of oral commensal bacteria detected in extra-oral lesions are warranted to comprehensively investigate the role of oral bacteria in the pathogenesis of systemic diseases.

Streptococcus Species Abundance in the Gut Is Linked to Subclinical Coronary Atherosclerosis in 8973 Participants From the SCAPIS Cohort

BACKGROUND

Gut microbiota have been implicated in atherosclerotic disease, but their relation with subclinical coronary atherosclerosis is unclear. This study aimed to identify associations between the gut microbiome and computed tomography-based measures of coronary atherosclerosis and to explore relevant clinical correlates.

METHODS

We conducted a cross-sectional study of 8973 participants (50 to 65 years of age) without overt atherosclerotic disease from the population-based SCAPIS (Swedish Cardiopulmonary Bioimage Study). Coronary atherosclerosis was measured using coronary artery calcium score and coronary computed tomography angiography. Gut microbiota species abundance and functional potential were assessed with shotgun metagenomics sequencing of fecal samples, and associations with coronary atherosclerosis were evaluated with multivariable regression models adjusted for cardiovascular risk factors. Associated species were evaluated for association with inflammatory markers, metabolites, and corresponding species in saliva.

RESULTS

The mean age of the study sample was 57.4 years, and 53.7% were female. Coronary artery calcification was detected in 40.3%, and 5.4% had at least 1 stenosis with >50% occlusion. Sixty-four species were associated with coronary artery calcium score independent of cardiovascular risk factors, with the strongest associations observed for Streptococcus anginosus and Streptococcus oralis subsp oralis (P<1×10-5). Associations were largely similar across coronary computed tomography angiography-based measurements. Out of the 64 species, 19 species, including streptococci and other species commonly found in the oral cavity, were associated with high-sensitivity C-reactive protein plasma concentrations, and 16 with neutrophil counts. Gut microbial species that are commonly found in the oral cavity were negatively associated with plasma indole propionate and positively associated with plasma secondary bile acids and imidazole propionate. Five species, including 3 streptococci, correlated with the same species in saliva and were associated with worse dental health in the Malmö Offspring Dental Study. Microbial functional potential of dissimilatory nitrate reduction, anaerobic fatty acid β-oxidation, and amino acid degradation were associated with coronary artery calcium score.

CONCLUSIONS

This study provides evidence of an association of a gut microbiota composition characterized by increased abundance of Streptococcus spp and other species commonly found in the oral cavity with coronary atherosclerosis and systemic inflammation markers. Further longitudinal and experimental studies are warranted to explore the potential implications of a bacterial component in atherogenesis.

Is discontinuation of dental treatment related to exacerbation of systemic medical diseases in Japan?

Aims Since it is known that oral problems affect various medical diseases, the effects of restrictions on visits for dental treatment on exacerbations of various systemic medical diseases were examined.Method and materials The data were used from the Japan COVID-19 and Society Internet Survey, a large-scale internet survey conducted in 2021 (n = 28,175). The questionnaires were distributed to 33,081 candidates who were selected to represent the Japanese population regarding age, sex and residential prefecture using a simple random sampling procedure. Patients currently undergoing treatment for diabetes mellitus, hypertension, asthma, cardiocerebrovascular disease, hyperlipidemia, atopic dermatitis, and mental illness, such as depression, were extracted from the total participants. Then, whether discontinuation of dental treatment affected the exacerbation of their systemic disease was examined.Results Overall, 50-60% of patients with each systemic disease had continued to receive dental treatment, and 4-8% of them had discontinued dental treatment. On univariate and multivariate analyses, discontinuation of dental treatment is a risk factor in the exacerbation of diabetes mellitus, hypertensive conditions, asthma, cardiocerebrovascular disease and hyperlipidemia.Conclusion The present epidemiological study showed the relationship between oral health and systemic health, which can provide meaningful insights regarding future medical-dental collaboration in Japan.

The Oral Microbiota in Valvular Heart Disease: Current Knowledge and Future Directions

Oral microbiota formation begins from birth, and everything from genetic components to the environment, alongside the host's behavior (such as diet, smoking, oral hygiene, and even physical activity), contributes to oral microbiota structure. Even though recent studies have focused on the gut microbiota's role in systemic diseases, the oral microbiome represents the second largest community of microorganisms, making it a new promising therapeutic target. Periodontitis and dental caries are considered the two main consequences of oral bacterial imbalance. Studies have shown that oral dysbiosis effects are not limited locally. Due to technological advancement, research identified oral bacterial species in heart valves. This evidence links oral dysbiosis with the development of valvular heart disease (VHD). This review focuses on describing the mechanism behind prolonged local inflammation and dysbiosis, that can induce bacteriemia by direct or immune-mediated mechanisms and finally VHD. Additionally, we highlight emerging therapies based on controlling oral dysbiosis, periodontal disease, and inflammation with immunological and systemic effects, that exert beneficial effects in VHD management.

The oral bacterium Streptococcus mutans promotes tumor metastasis by inducing vascular inflammation

Recent studies have demonstrated a relationship between oral bacteria and systemic inflammation. Endothelial cells (ECs), which line blood vessels, control the opening and closing of the vascular barrier and contribute to hematogenous metastasis; however, the role of oral bacteria-induced vascular inflammation in tumor metastasis remains unclear. In this study, we examined the phenotypic changes in vascular ECs following Streptococcus mutans (S. mutans) stimulation in vitro and in vivo. The expression of molecules associated with vascular inflammation and barrier-associated adhesion was analyzed. Tumor metastasis was evaluated after intravenous injection of S. mutans in murine breast cancer hematogenous metastasis model. The results indicated that S. mutans invaded the ECs accompanied by inflammation and NF-κB activation. S. mutans exposure potentially disrupts endothelial integrity by decreasing VE-cadherin expression. The migration and adhesion of tumor cells were enhanced in S. mutans-stimulated ECs. Furthermore, S. mutans-induced lung vascular inflammation promoted breast cancer cell metastasis to the lungs in vivo. The results indicate that oral bacteria promote tumor metastasis through vascular inflammation and disruption of vascular barrier function. Improving oral hygiene in patients with cancer is of great significance in preventing postoperative pneumonia and tumor metastasis.

The salivary metatranscriptome as an accurate diagnostic indicator of oral cancer

Despite advances in cancer treatment, the 5-year mortality rate for oral cancers (OC) is 40%, mainly due to the lack of early diagnostics. To advance early diagnostics for high-risk and average-risk populations, we developed and evaluated machine-learning (ML) classifiers using metatranscriptomic data from saliva samples (n = 433) collected from oral premalignant disorders (OPMD), OC patients (n = 71) and normal controls (n = 171). Our diagnostic classifiers yielded a receiver operating characteristics (ROC) area under the curve (AUC) up to 0.9, sensitivity up to 83% (92.3% for stage 1 cancer) and specificity up to 97.9%. Our metatranscriptomic signature incorporates both taxonomic and functional microbiome features, and reveals a number of taxa and functional pathways associated with OC. We demonstrate the potential clinical utility of an AI/ML model for diagnosing OC early, opening a new era of non-invasive diagnostics, enabling early intervention and improved patient outcomes.

Type IV Pili of Streptococcus sanguinis Contribute to Pathogenesis in Experimental Infective Endocarditis

Streptococcus sanguinis is a common cause of infective endocarditis (IE). Efforts by research groups are aimed at identifying and characterizing virulence factors that contribute to the ability of this organism to cause IE. This Gram-positive pathogen causes heart infection by gaining access to the bloodstream, adhering to host extracellular matrix protein and/or platelets, colonizing the aortic endothelium, and incorporating itself into the aortic vegetation. While many virulence factors have been reported to contribute to the ability of S. sanguinis to cause IE, it is noteworthy that type IV pili (T4P) have not been described to be a virulence factor in this organism, although S. sanguinis strains typically encode these pili. Type IV pili are molecular machines that are capable of mediating diverse virulence functions and surface motility. T4P have been shown to mediate twitching motility in some strains of S. sanguinis, although in most strains it has been difficult to detect twitching motility. While we found that T4P are dispensable for direct in vitro platelet binding and aggregation phenotypes, we show that they are critical to the development of platelet-dependent biofilms representative of the cardiac vegetation. We also observed that T4P are required for in vitro invasion of S. sanguinis into human aortic endothelial cells, which indicates that S. sanguinis may use T4P to take advantage of an intracellular niche during infection. Importantly, we show that T4P of S. sanguinis are critical to disease progression (vegetation development) in a native valve IE rabbit model. The results presented here expand our understanding of IE caused by S. sanguinis and identify T4P as an important virulence factor for this pathogen.

IMPORTANCE This work provides evidence that type IV pili produced by Streptococcus sanguinis SK36 are critical to the ability of these bacteria to attach to and colonize the aortic heart valve (endocarditis). We found that an S. sanguinis type IV pili mutant strain was defective in causing platelet-dependent aggregation in a 24-h infection assay but not in a 1-h platelet aggregation assay, suggesting that the type IV pili act at later stages of vegetation development. In a rabbit model of disease, a T4P mutant strain does not develop mature vegetations that form on the heart, indicating that this virulence factor is critical to disease and could be a target for IE therapy.

Streptococcus mutans in atherosclerotic plaque: Molecular and immunohistochemical evaluations

OBJECTIVES

To verify the presence of Streptococcus mutans (S. mutans) in atherosclerotic plaque (AP) using techniques with different sensitivities, correlating with histological changes in plaque and immunoexpression of inflammatory markers.

MATERIALS AND METHODS

Thirteen AP samples were subjected to real-time polymerase chain reaction (qRT-PCR), histopathological analyses, histochemical analysis by Giemsa staining (GS), and immunohistochemical analysis for S. mutans, IL-1β, and TNF-α (streptavidin-biotin-peroxidase method). Ten necropsy samples of healthy vessels were used as controls.

RESULTS

All AP samples showed histopathological characteristics of severe atherosclerosis and were positive for S. mutans (100.0%) in qRT-PCR and immunohistochemical analyses. GS showed that Streptococcus sp. colonized the lipid-rich core regions and fibrous tissue, while the control group was negative for Streptococcus sp. IL-1β and TNF-α were expressed in 100% and 92.3% of the AP tested, respectively. The control samples were positive for S. mutans in qRT-PCR analysis, but negative for S. mutans, IL-1β, and TNF-α in immunohistochemical analyses.

CONCLUSION

The detection of S. mutans in AP and the visualization of Streptococcus sp. suggested a possible association between S. mutans and atherosclerosis. The results obtained from the control samples suggested the presence of DNA fragments or innocuous bacteria that were not associated with tissue alteration. However, future studies are necessary to provide more information.

Potential involvement of Streptococcus mutans possessing collagen binding protein Cnm in infective endocarditis

Streptococcus mutans, a significant contributor to dental caries, is occasionally isolated from the blood of patients with infective endocarditis. We previously showed that S. mutans strains expressing collagen-binding protein (Cnm) are present in the oral cavity of approximately 10-20% of humans and that they can effectively invade human umbilical vein endothelial cells (HUVECs). Here, we investigated the potential molecular mechanisms of HUVEC invasion by Cnm-positive S. mutans. The ability of Cnm-positive S. mutans to invade HUVECs was significantly increased by the presence of serum, purified type IV collagen, and fibrinogen (p < 0.001). Microarray analyses of HUVECs infected by Cnm-positive or -negative S. mutans strains identified several transcripts that were differentially upregulated during invasion, including those encoding the small G protein regulatory proteins ARHGEF38 and ARHGAP9. Upregulation of these proteins occurred during invasion only in the presence of serum. Knockdown of ARHGEF38 strongly reduced HUVEC invasion by Cnm-positive S. mutans. In a rat model of infective endocarditis, cardiac endothelial cell damage was more prominent following infection with a Cnm-positive strain compared with a Cnm-negative strain. These results suggest that the type IV collagen-Cnm-ARHGEF38 pathway may play a crucial role in the pathogenesis of infective endocarditis.

Presence of bacterial DNA in thrombotic material of patients with myocardial infarction

Infectious agents have been suggested to be involved in etiopathogenesis of Acute Coronary Syndrome (ACS). However, the relationship between bacterial infection and acute myocardial infarction (AMI) has not yet been completely clarified. The objective of this study is to detect bacterial DNA in thrombotic material of patients with ACS with ST-segment elevation (STEMI) treated with Primary Percutaneous Coronary Intervention (PPCI). We studied 109 consecutive patients with STEMI, who underwent thrombus aspiration and arterial peripheral blood sampling. Testing for bacterial DNA was performed by probe-based real-time Polymerase Chain Reaction (PCR). 12 probes and primers were used for the detection of Aggregatibacter actinomycetemcomitans, Chlamydia pneumoniae, viridans group streptococci, Porphyromonas gingivalis, Fusobacterium nucleatum, Tannarella forsythia, Treponema denticola, Helycobacter pylori, Mycoplasma pneumoniae, Staphylococus aureus,  Prevotella intermedia and Streptococcus mutans. Thus, DNA of four species of bacteria was detected in 10 of the 109 patients studied. The most frequent species was viridans group streptococci (6 patients, 5.5%), followed by Staphylococus aureus (2 patients, 1.8%). Moreover, a patient had DNA of Porphyromonas gingivalis (0.9%); and another patient had DNA of Prevotella intermedia (0.9%). Bacterial DNA was not detected in peripheral blood of any of our patients. In conclusion, DNA of four species of endodontic and periodontal bacteria was detected in thrombotic material of 10 STEMI patients. Bacterial DNA was not detected in the peripheral blood of patients with bacterial DNA in their thrombotic material. Bacteria could be latently present in plaques and might play a role in plaque instability and thrombus formation leading to ACS.

Biofilm growth and IL-8 & TNF-α-inducing properties of Candida albicans in the presence of oral gram-positive and gram-negative bacteria

Background

Interaction of C. albicans with oral bacteria is crucial for its persistence, but also plays a potential role in the infection process. In the oral cavity, it grows as part of dental plaque biofilms. Even though growth and interaction of C. albicans with certain bacterial species has been studied, little is known about its biofilm growth in vitro in the simultaneous presence of Gram-negative and Gram-positive bacteria. The aim was to evaluate the growth of C. albicans in polymicrobial biofilms comprising oral Gram-negative and Gram-positive bacteria. Further, we also aimed to assess the potential of C. albicans in the Candida-bacteria polymicrobial biofilm to elicit cytokine gene expression and cytokine production from human blood cells.

Results

C. albicans cell counts increased significantly up to 48 h in polymicrobial biofilms (p < 0.05), while the bacterial counts in the same biofilms increased only marginally as revealed by qPCR absolute quantification. However, the presence of bacteria in the biofilm did not seem to affect the growth of C. albicans. Expression of IL-8 gene was significantly (p < 0.05) higher upon stimulation from biofilm-supernatants than from biofilms in polymicrobial setting. On the contrary, TNF-α expression was significantly higher in biofilms than in supernatants but was very low (1–4 folds) in the monospecies biofilm of C. albicans. ELISA cytokine quantification data was in agreement with mRNA expression results.

Conclusion

Persistence and enhanced growth of C. albicans in polymicrobial biofilms may imply that previously reported antagonistic effect of A. actinomycetemcomitans was negated. Increased cytokine gene expression and cytokine production induced by Candida-bacteria polymicrobial biofilms and biofilm supernatants suggest that together they possibly exert an enhanced stimulatory effect on IL-8 and TNF-α production from the host.

In Vitro Effects of Streptococcus oralis Biofilm on Peri-Implant Soft Tissue Cells

Human gingival epithelial cells (HGEps) and fibroblasts (HGFs) are the main cell types in peri-implant soft tissue. HGEps are constantly exposed to bacteria, but HGFs are protected by connective tissue as long as the mucosa-implant seal is intact. Streptococcus oralis is one of the commensal bacteria, is highly abundant at healthy implant sites, and might modulate soft tissue cells-as has been described for other streptococci. We have therefore investigated the effects of the S. oralis biofilm on HGEps and HGFs. HGEps or HGFs were grown separately on titanium disks and responded to challenge with S. oralis biofilm. HGFs were severely damaged after 4 h, exhibiting transcriptional inflammatory and stress responses. In contrast, challenge with S. oralis only induced a mild transcriptional inflammatory response in HGEps, without cellular damage. HGFs were more susceptible to the S. oralis biofilm than HGEps. The pro-inflammatory interleukin 6 (IL-6) was attenuated in HGFs, as was interleukin 8 (CXCL8) in HGEps. This indicates that S. oralis can actively protect tissue. In conclusion, commensal biofilms can promote homeostatic tissue protection, but only if the implant-mucosa interface is intact and HGFs are not directly exposed.

Effects of Oral Commensal Streptococci on Porphyromonas gingivalis Invasion into Oral Epithelial Cells

The objective of this study was to determine if the interaction between common oral commensal bacteria and oral epithelial cells would provide protective effects against the invasion of periodontopathogen Porphyromonas gingivalis. Oral epithelial OKF6/Tert cells were used in co-cultures with Streptococcus gordonii, Streptococcus oralis, Streptococcus mitis, and Streptococcus intermedius. The viability of OKF6/Tert cells following a bacterial challenge was evaluated by trypan blue exclusion. The adherence of commensal species was determined by CFU counts. P. gingivalis invasion in OKF6/Tert cells was assessed before and after exposure to commensal species according to CFU counts. Viability assays show that only S. gordonii and S. intermedius display low toxicity toward OKF6/Tert cells. Both commensals adhere to OKF6/Tert cells at an average ratio of 1 CFU to 10 cells. P. gingivalis invasion into host cells is significantly reduced by 25% or 60% after exposure to S. gordonii or S. intermedius, respectively. The results suggest that these commensal species bind to host cells and diminish P. gingivalis invasion. This is important in the context of periodontal disease since P. gingivalis primarily acts on the host by invading it. Therefore, efforts to decrease invasion will eventually lead to future therapies harnessing the mechanisms employed by oral commensal bacteria.

One-year follow-up study on associations between dental caries, periodontitis, and metabolic syndrome

There have been few prospective studies on the relationship between oral health conditions and the development of metabolic syndrome (MetS). This prospective cohort study was performed at a Japanese company over one year. Routine medical health examinations, oral health examinations, and a questionnaire pertaining to education, job type, and health behaviors was administered. Participants aged ≥35 years who had no MetS components at baseline were re-examined after one year. Modified Poisson regression analyses were performed to calculate the relative risks (RRs) associated with oral health variables, including periodontitis, decayed and missing teeth, and decayed, missing, and filled teeth (DMFT) in relation to the development of MetS. Of 152 eligible participants, 136 were re-examined after one year; 30 exhibited one or more newly developed MetS components upon re-examination. Decayed teeth at baseline were significantly associated with development of at least one MetS component (adjusted RR 3.25, 95% confidence interval 1.59-6.63). There were no associations between periodontitis, missing teeth, or DMFT and the development of MetS. The association between decayed teeth and MetS was independent of other risk factors, including age and body mass index; therefore, decayed teeth may be associated with the development of MetS.

Associations between caries experience, dietary habits, and metabolic syndrome in Japanese adults

Dental caries could be a risk factor for metabolic syndrome (MetS); however, there is limited evidence of such a relationship in the literature. This cross-sectional study investigated the relationships among dental caries experience, dietary habits, and MetS in Japanese adults. A total of 937 participants aged 40-74 years underwent a health check, including dental examination. Decayed, missing, and filled teeth (DMFT) were used as an index of caries experience. The mean DMFT score was 14, and 12% of the participants had MetS in this study. Multivariate logistic regression analyses showed that the prevalence of MetS was significantly related to DMFT (first vs. fourth quartile, odds ratio [OR] = 1.80; P < 0.05). In addition, the OR of DMFT for MetS was found to be greater in each successively higher DMFT quartile. The prevalence of MetS was significantly related to daily coffee consumption (OR = 0.51, P < 0.01), and the relationship between DMFT and MetS was noted after adjusting for daily coffee consumption. There appears to be a positive association between caries experience and MetS in Japanese adults. This relationship increased with the increase in DMFT regardless of dietary habits.

Relationship of Streptococcus mutans with valvar cardiac tissue: A molecular and immunohistochemical study

BACKGROUND

The present study aimed to investigate the presence or absence of Streptococcus mutans in oral cavity and valvular samples associating with the histomorphologic alterations of calcified aortic stenosis.

METHODOLOGY

Dental plaque and cardiac valve samples were collected from 10 patients with calcified aortic stenosis for molecular analysis of S mutans by real-time polymerase chain reaction (PCR). Healthy valve tissue was also collected from five young cadavers and analyzed for S mutans. Moreover, fragments of all valvar specimens were submitted for histomorphological analysis and immunohistochemistry (anti-S mutans and anti-CD61).

RESULTS

Streptococcus mutans was present in 100% of the oral cavity samples from the patients with calcified aortic stenosis in the molecular analysis. The analysis by real-time PCR showed that S mutans presented the same proportion in healthy valves and those with calcified aortic stenosis (80%; P = 1.000). Conversely, the immunoexpression of S mutans was 37.40 (IC95% = 1.49-937.00) times superior in samples of patients with cardiac disease (P = .007). The immunoexpression analysis showed that CD61 was present in seven (70%) calcified aortic stenosis samples, all of which were also immunopositive for S mutans.

CONCLUSIONS

Streptococcus mutans was found in the oral cavity, healthy valve tissue, and calcified aortic stenosis samples. However, the microorganism was visualized by immunohistochemistry only in the calcified aortic stenosis samples, which may suggest viability and an increased bacterial density in this condition. The association of the presence of S mutans and positive CD61 immunoexpression suggests a probable relationship with calcified aortic stenosis.

DMBT1 involvement in the human aortic endothelial cell response to Streptococcus mutans

Streptococcus mutans is a causative organism of dental caries and has been reported to be associated with the development of cardiovascular disease (CVD). Previous studies have demonstrated that S. mutans invades human aortic endothelial cells (HAECs) and HAECs invaded by S. mutans produce higher levels of CVD-related cytokines than non-invaded HAECs. DMBT1 (deleted in malignant brain tumors 1), also known as salivary agglutinin or gp-340, belongs to the scavenger receptor cysteine-rich superfamily. DMBT1 is expressed in epithelial and non-epithelial tissues and has multiple functions. The interaction between S. mutans and DMBT1 has been demonstrated in cariogenesis, but DMBT1 involvement in CVD has not been examined. In this study, we investigated DMBT1 expression in HAECs stimulated with S. mutans and examined the role of DMBT1 in the interaction between S. mutans and HAECs. All of the tested S. mutans strains induced higher production levels of DMBT1 in HAECs than those in unstimulated HAECs. More S. mutans cells adhered to DMBT1 knock down HAECs than to DMBT1-producing HAECs. Invasion of DMBT1 knock down HAECs by S. mutans was stronger than that of DMBT1-producing HAECs, and externally added DMBT1 reduced bacterial invasion. Cytokine production by DMBT1 knock down HAECs by S. mutans stimulation was higher than that by DMBT1-producing HAECs. These phenomena seemed to be due to the effect of released DMBT1, namely, the inhibition of bacterial adherence to HAECs by DMBT1. These results suggest that DMBT1 plays a protective role against the S. mutans-induced CVD process in HAECs.

Pseudomonas aeruginosa Invades Human Aortic Endothelial Cells and Induces Cell Damage in vitro

BACKGROUND

Cardiovascular diseases such as endocarditis are the second most common cause of death worldwide. Infective Endocarditis (IE) is the most severe infection of the heart associated with significant mortality and morbidity. The binding and invasion of Human Aortic Endothelial Cells (HAECs) by pathogenic microbes can play an important role in the pathogenesis of IE.

OBJECTIVE

Pseudomonas aeruginosa is an emerging pathogen that has been associated with IE. However, it is not known whether P. aeruginosa can bind and interact with HAECs. The aim of this study was to determine whether P. aeruginosa can bind and colonize HAECs.

METHODS

The invasion of HAECs by P. aeruginosa was assessed by gentamicin protection assay. Cytokine levels were determined by enzyme-linked Immunosorbent Assay (ELISA) kits. Cell damage was determined by Lactate Dehydrogenase (LDH) assay.

RESULTS

P. aeruginosa can bind and invade HAECs. Infection of HAECs with P. aeruginosa induces TNF-α IL-1β, IL-6 and IL-8 cytokine production leading to the generation of inflammatory milieu that can cause tissue damage as observed in human clinical cases of IE. We also observed that P. aeruginosa induces cell damage in HAECs.

CONCLUSION

In this study, we demonstrate for first time that P. aeruginosa can invade and survive inside HAECs. This cell culture model can be of immense importance to determine the efficacy of drug targets against IE.

Inhibitory effect of surface pre-reacted glass-ionomer (S-PRG) eluate against adhesion and colonization by Streptococcus mutans

Surface Pre-reacted Glass-ionomer (S-PRG) filler is a bioactive filler produced by PRG technology, which has been applied to various dental materials. A S-PRG filler can release multiple ions from a glass-ionomer phase formed in the filler. In the present study, detailed inhibitory effects induced by S-PRG eluate (prepared with S-PRG filler) against Streptococcus mutans, a major pathogen of dental caries, were investigated. S-PRG eluate effectively inhibited S. mutans growth especially in the bacterium before the logarithmic growth phase. Microarray analysis was performed to identify changes in S. mutans gene expression in the presence of the S-PRG eluate. The S-PRG eluate prominently downregulated operons related to S. mutans sugar metabolism, such as the pdh operon encoding the pyruvate dehydrogenase complex and the glg operon encoding a putative glycogen synthase. The S-PRG eluate inhibited several in vitro properties of S. mutans relative to the development of dental caries especially prior to active growth. These results suggest that the S-PRG eluate may effectively inhibit the bacterial growth of S. mutans following downregulation of operons involved in sugar metabolism resulting in attenuation of the cariogenicity of S. mutans, especially before the active growth phase.

Molecular mechanisms driving Streptococcus mitis entry into human gingival fibroblasts in presence of chitlac-nAg and saliva

The molecular mechanisms leading to Streptococcus mitis capability of entering oral cells were investigated in a co-culture of S. mitis and Human Gingival Fibroblasts (HGFs) in the presence of saliva. An innovative colloidal solution based on silver nanoparticles (Chitlac-nAg), a promising device for daily oral care, was added to the experimental system in order to study the effects of silver on the bacterial overgrowth and ability to enter non-phagocytic eukaryotic cells. The entry of bacteria into the eukaryotic cells is mediated by a signalling pathway involving FAK, integrin β1, and the two cytoskeleton proteins vinculin and F-actin, and down-regulated by the presence of saliva both at 3 and 48 h of culture, whereas Chitlac-n Ag exposure seems to influence, by incrementing it, the number of bacteria entering the fibroblasts only at 48 h. The formation of fibrillary extrusion from HGFs and the co-localization of bacteria and silver nanoparticles within the fibroblast vacuoles were also recorded. After longer experimental times (72 and 96 h), the number of S. mitis chains inside gingival cells is reduced, mainly in presence of saliva. The results suggest an escape of bacteria from fibroblasts to restore the microbial balance of the oral cavity.

Influence of excess branched-chain amino acid uptake by Streptococcus mutans in human host cells

Oral streptococci, including cariogenic bacterium Streptococcus mutans, comprise a large percentage of human supragingival plaque, which contacts both tooth surfaces and gingiva. Eukaryotic cells are able to take up macromolecules and particles, including bacteria, by endocytosis. Increasing evidence indicates endocytosis may be used as an entry process by bacteria. We hypothesized that some endocytosed bacteria might survive and obtain nutrients, such as amino acids, until they are killed. To verify this hypothesis, we focused on bacterial utilization of branched-chain amino acids (BCAAs; isoleucine, leucine and valine) in host cells. A branched-chain aminotransferase, IlvE (EC 2.6.1.42), has been suggested to play an important role in internal synthesis of BCAAs in S. mutans UA159. Therefore, we constructed an ilvE-deficient S. mutans 109c strain and confirmed that it had similar growth behavior as reported previously. 14C radioactive leucine uptake assays showed that ilvE-deficient S. mutans took up more leucine both inside and outside of host cells. We further clarified that a relative decrease of BCAAs in host cells caused enhanced endocytic and autophagic activity. In conclusion, S. mutans is endocytosed by host cells and may survive and obtain nutrients, such as BCAAs, inside the cells, which might affect cellular functions of host cells.

Cytokine induction of peripheral blood mononuclear cells by biofilms and biofilm supernatants of Granulicatella and Abiotrophia spp

Granulicatella and Abiotrophia species are the normal oral flora bacteria that can occasionally cause infective endocarditis. Although substantial data exists in the literature demonstrating occurrence of these species in infective endocarditis, only a few mechanistic studies on their pathogenicity are found. The aim of this study was to investigate the ability of Granulicatella and Abiotrophia species to elicit immune response from human peripheral blood mononuclear cells (PBMC). Biofilms and biofilm supernatants of Granulicatella elegans CCUG 38949, Granulicatella adiacens CCUG 27809 and Abiotrophia defectiva CCUG 27639 were used to stimulate PBMCs for 24 h. Cytokines produced were first screened using a human cytokine membrane array kit. Further, pro-inflammatory cytokines TNF-α, IL-β, and IL-17 were quantified by ELISA. The cytokine profiler array showed the induction of 15 different cytokines/chemokines including IL-1β, IL-6, IL-8, TNF-α, MCP-1, MIP-1α/MIP-1β and RANTES. ELISA quantification revealed that G. adiacens biofilm induced significantly higher (P < 0.05) levels of IL-1β, i.e., 1931 (183) pg/ml than G. elegans or A. defectiva. However, in the case of biofilm supernatants A. defectiva was the strongest, inducing 2104 (574) pg/ml. Biofilm supernatants, but not biofilms from all three species induced TNF-α only weakly. IL-17 was undetectable from any of the stimulated samples. In conclusion, Granulicatella and Abiotrophia are potent inducers of inflammatory mediators from human PBMCs. However, biofilms and biofilm supernatants from these species seem to selectively elicit stimulation of certain cytokines.

Contribution of Streptococcus mutans Strains with Collagen-Binding Proteins in the Presence of Serum to the Pathogenesis of Infective Endocarditis

Streptococcus mutans, a major pathogen of dental caries, is considered one of the causative agents of infective endocarditis (IE). Recently, bacterial DNA encoding 120-kDa cell surface collagen-binding proteins (CBPs) has frequently been detected from S. mutans-positive IE patients. In addition, some of the CBP-positive S. mutans strains lacked a 190-kDa protein antigen (PA), whose absence strengthened the adhesion to and invasion of endothelial cells. The interaction between pathogenic bacteria and serum or plasma is considered an important virulence factor in developing systemic diseases; thus, we decided to analyze the pathogenesis of IE induced by S. mutans strains with different patterns of CBP and PA expression by focusing on the interaction with serum or plasma. CBP-positive (CBP⁺)/PA-negative (PA^-) strains showed prominent aggregation in the presence of human serum or plasma, which was significantly greater than that with CBP⁺/PA-positive (PA⁺) and CBP-negative (CBP^-)/PA+ strains. Aggregation of CBP⁺/PA^- strains was also observed in the presence of a high concentration of type IV collagen, a major extracellular matrix protein in serum. In addition, aggregation of CBP⁺/PA^- strains was drastically reduced when serum complement was inactivated. Furthermore, an ex vivo adherence model and an in vivo rat model of IE showed that extirpated heart valves infected with CBP⁺/PA^- strains displayed prominent bacterial mass formation, which was not observed following infection with CBP⁺/PA⁺ and CBP^-/PA⁺ strains. These results suggest that CBP⁺/PA^-S. mutans strains utilize serum to contribute to their pathogenicity in IE.

Evidence for polymicrobial communities in explanted vascular filters and atheroma debris

RATIONALE

Microbial communities have been implicated in a variety of disease processes and have been intermittently observed in arterial disease; however, no comprehensive unbiased community analysis has been performed. We hypothesize that complex microbial communities may be involved in chronic vascular diseases as well and may be effectively characterized by molecular assays.

OBJECTIVE

The main objective is to survey vascular debris, atheroma, and vascular filters for polymicrobial communities consisting of prokaryotic and eukaryotic microbes, specifically eukaryotic microbes.

METHODS AND RESULTS

We examined vascular aspirates of atheromatous debris or embolic protection filters in addition to matched peripheral blood samples, from fifteen patients, as well as three cadaveric coronary arteries from two separate patients, for microbial communities. General fluorescence microscopy by Höechst and ethidium bromide DNA stains, prokaryotic and eukaryotic community analysis by Next Generation DNA Sequencing (NGS), and a eukaryotic microbial 9 probe multiplexed quantitative PCR were used to detect and characterize the presence of putative polymicrobial communities. No prokaryotes were detected in peripheral blood; however, in 4 of 9 sequenced filters and in 2 of 7 sequenced atheroma debris samples, prokaryotic populations were identified. By DNA sequencing, eukaryotic microbes were detected in 4 of 15 blood samples, 5 of the 9 sequenced filters, and 3 of the 7 atheroma debris samples. The quantitative multiplex PCR detected sequences consistent with eukaryotic microbes in all 9 analyzed filter samples as well as 5 of the 7 atheroma debris samples. Microscopy reveals putative polymicrobial communities within filters and atheroma debris. The main contributing prokaryotic species in atheroma debris suggest a diverse and novel composition. Additionally, Funneliformis mosseae, an arbuscular mycorrhizal fungus in the Glomeraceae family, was detected in the coronary hard plaque from two patients. Well studied biofilm forming bacteria were not detectable in circulating peripheral blood and were not universally present in atheroma or filters. Analyses of the sequenced eukaryotes are consistent with a diverse of array poorly studied environmental eukaryotes. In summary, out of 15 patients, 6 exhibited molecular evidence of prokaryotes and 14 had molecular evidence of eukaryotic and/or polymicrobial communities in vivo, while 2 post-mortem coronary plaque samples displayed evidence of fungi.

CONCLUSION

Prokaryotes are not consistently observed in atheroma debris or filter samples; however, detection of protozoa and fungi in these samples suggests that they may play a role in arterial vascular disease or atheroma formation.

Invasive Streptococcus mutans induces inflammatory cytokine production in human aortic endothelial cells via regulation of intracellular toll-like receptor 2 and nucleotide-binding oligomerization domain 2

Streptococcus mutans, the primary etiologic agent of dental caries, can gain access to the bloodstream and has been associated with cardiovascular disease. However, the roles of S. mutans in inflammation in cardiovascular disease remain unclear. The aim of this study was to examine cytokine production induced by S. mutans in human aortic endothelial cells (HAECs) and to evaluate the participation of toll-like receptors (TLRs) and cytoplasmic nucleotide-binding oligomerization domain (NOD) -like receptors in HAECs. Cytokine production by HAECs was determined using enzyme-linked immunosorbent assays, and the expression of TLRs and NOD-like receptors was evaluated by real-time polymerase chain reaction, flow cytometry and immunocytochemistry. The involvement of TLR2 and NOD2 in cytokine production by invaded HAECs was examined using RNA interference. The invasion efficiencies of S. mutans strains were evaluated by means of antibiotic protection assays. Five of six strains of S. mutans of various serotypes induced interleukin-6, interleukin-8 and monocyte chemoattractant protein-1 production by HAECs. All S. mutans strains upregulated TLR2 and NOD2 mRNA levels in HAECs. Streptococcus mutans Xc upregulated the intracellular TLR2 and NOD2 protein levels in HAECs. Silencing of the TLR2 and NOD2 genes in HAECs invaded by S. mutans Xc led to a reduction in interleukin-6, interleukin-8 and monocyte chemoattractant protein-1 production. Cytokine production induced by invasive S. mutans via intracellular TLR2 and NOD2 in HAECs may be associated with inflammation in cardiovascular disease.

Collagen-binding proteins of Streptococcus mutans and related streptococci

The ability of Streptococcus mutans to interact with collagen through the expression of collagen-binding proteins (CBPs) bestows this oral pathogen with an alternative to the sucrose-dependent mechanism of colonization classically attributed to caries development. Based on the abundance and distribution of collagen throughout the human body, stringent adherence to this molecule grants S. mutans with the opportunity to establish infection at different host sites. Surface proteins, such as SpaP, WapA, Cnm and Cbm, have been shown to bind collagen in vitro, and it has been suggested that these molecules play a role in colonization of oral and extra-oral tissues. However, robust collagen binding is not achieved by all strains of S. mutans, particularly those that lack Cnm or Cbm. These observations merit careful dissection of the contribution from these different CBPs towards tissue colonization and virulence. In this review, we will discuss the current understanding of mechanisms used by S. mutans and related streptococci to colonize collagenous tissues, and the possible contribution of CBPs to infections in different sites of the host.

Orthopedic implant infections: Incompetence of Staphylococcus epidermidis, Staphylococcus lugdunensis, and Enterococcus faecalis to invade osteoblasts

Septic failure is still the major complication of prosthetic implants. Entering host cells, bacteria hide from host immune defenses, shelter from extracellular antibiotics, and cause chronic infection. Staphylococcus aureus, the leading etiologic agent of orthopedic implant infections, is able to enter bone cells and induce osteoblast apoptosis, osteoclast recruitment, and highly destructive osteomyelitis. Staphylococcus epidermidis, Staphylococcus lugdunensis, and Enterococcus faecalis are opportunistic pathogens causative of implant-related infections. This study investigated the ability to internalize into osteoblastic MG63 cells of 22 S. epidermidis, 9 S. lugdunensis, and 21 E. faecalis clinical isolates from orthopedic implant infections. Isolates were categorized in clusters by ribotyping. Internalization assay was carried out by means of a microtiter plate-based method. S. epidermidis, S. lugdunensis, and E. faecalis strains turned out incompetent to enter osteoblasts, exhibiting negligible internalization into MG63 cells, nearly three orders of magnitude lower than that of S. aureus. Osteoblast invasion does not appear as a pathogenetic mechanism utilized by S. epidermidis, S. lugdunensis, or E. faecalis for infecting orthopedic implants. Moreover, it can be inferred that intracellularly active antimicrobials should not be necessary against implant infections caused by the three bacterial species. Finally, implications with the uptake of biomaterial microparticles by nonphagocytic cells are enlightened. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 788-801, 2016.

Molecular Analysis of Oral Bacteria in Heart Valve of Patients With Cardiovascular Disease by Real-Time Polymerase Chain Reaction

Structural deficiencies and functional abnormalities of heart valves represent an important cause of cardiovascular morbidity and mortality, and a number of diseases, such as aortic stenosis, have been recently associated with infectious agents. This study aimed to analyze oral bacteria in dental plaque, saliva, and cardiac valves of patients with cardiovascular disease. Samples of supragingival plaque, subgingival plaque, saliva, and cardiac valve tissue were collected from 42 patients with heart valve disease. Molecular analysis of Streptococcus mutans, Prevotella intermedia, Porphyromonas gingivalis, and Treponema denticola was performed through real-time PCR. The micro-organism most frequently detected in heart valve samples was the S. mutans (89.3%), followed by P. intermedia (19.1%), P. gingivalis (4.2%), and T. denticola (2.1%). The mean decayed, missing, filled teeth (DMFT) was 26.4 ± 6.9 (mean ± SD), and according to the highest score of periodontal disease observed for each patient, periodontal pockets > 4 mm and dental calculus were detected in 43.4% and 34.7% of patients, respectively. In conclusion, oral bacteria, especially S. mutans, were found in the cardiac valve samples of patients with a high rate of caries and gingivitis/periodontitis.

The use of 2% chlorhexidine gel and toothbrushing for oral hygiene of patients receiving mechanical ventilation: effects on ventilator-associated pneumonia

Objective

To evaluate the effects of oral chlorhexidine hygiene with toothbrushing on the rate of ventilator-associated pneumonia in a mixed population of critically ill patients under prolonged mechanical ventilation.

Methods

Prospective, randomized, and placebo-controlled pilot study. Patients who were receiving mechanical ventilation, had been admitted less than 24 hours prior, and were anticipated to require mechanical ventilation for more than 72 hours were included in the study. The patients were randomly divided into one of the following groups: chlorhexidine hygiene with toothbrushing or a placebo group (gel with the same color and consistency and toothbrushing).

Results

The planned interim analysis was conducted using 52 patients, and the study was terminated prematurely. In total, 28 patients were included in the chlorhexidine / toothbrushing group, and 24 patients were included in the placebo group. Ventilator-associated pneumonia occurred in 45.8% of the placebo group and in 64.3% of the chlorhexidine hygiene with toothbrushing group (RR=1.4; 95% CI=0.83-2.34; p=0.29).

Conclusion

Because the study was terminated due to futility, it was not possible to evaluate the impact of oral hygiene using 2% chlorhexidine and toothbrushing on the incidence of ventilator-associated pneumonia in this heterogeneous population of critical patients receiving long-term mechanical ventilation, and no beneficial effect was observed for this intervention.

The dormant blood microbiome in chronic, inflammatory diseases

Blood in healthy organisms is seen as a ‘sterile’ environment: it lacks proliferating microbes. Dormant or not-immediately-culturable forms are not absent, however, as intracellular dormancy is well established. We highlight here that a great many pathogens can survive in blood and inside erythrocytes. ‘Non-culturability’, reflected by discrepancies between plate counts and total counts, is commonplace in environmental microbiology. It is overcome by improved culturing methods, and we asked how common this would be in blood. A number of recent, sequence-based and ultramicroscopic studies have uncovered an authentic blood microbiome in a number of non-communicable diseases. The chief origin of these microbes is the gut microbiome (especially when it shifts composition to a pathogenic state, known as ‘dysbiosis’). Another source is microbes translocated from the oral cavity. ‘Dysbiosis’ is also used to describe translocation of cells into blood or other tissues. To avoid ambiguity, we here use the term ‘atopobiosis’ for microbes that appear in places other than their normal location. Atopobiosis may contribute to the dynamics of a variety of inflammatory diseases. Overall, it seems that many more chronic, non-communicable, inflammatory diseases may have a microbial component than are presently considered, and may be treatable using bactericidal antibiotics or vaccines.

Atopobiosis of microbes (the term describing microbes that appear in places other than where they should be), as well as the products of their metabolism, seems to correlate with, and may contribute to, the dynamics of a variety of inflammatory diseases.

Interleukin-6 and microRNA profiles induced by oral bacteria in human atheroma derived and healthy smooth muscle cells

BACKGROUND

Atherosclerosis is an inflammatory disease with possible contributions from bacterial antigens. We aimed to investigate the role of oral bacteria as inducers of inflammatory cascades in smooth muscle cells from carotid endarterectomy patients (AthSMCs) and healthy controls (HSMCs).

FINDINGS

Inactivated Streptococcus mitis, S. sanguinis, S. gorgonii, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were used to stimulate inflammation in HSMCs and AthSMCs. Tumor necrosis factor-α (TNFα) was used as a positive control in all stimulations. Interleukin-6 (IL-6) levels were determined from cell culture supernatants and microRNA expression profiles from cells after 24 h of bacterial stimulation. Genome wide expression (GWE) analyses were performed after 5 h stimulation. All studied bacteria induced pro inflammatory IL-6 production in both SMCs. The most powerful inducer of IL-6 was A. actinomycetemcomitans (p < 0.001). Of the 84 studied miRNAs, expression of 9 miRNAs differed significantly (p ≤ 0.001) between HSMCs and AthSMCs stimulated with inactivated bacteria or TNFα. The data was divided into two groups: high IL-6 producers (A. actinomytectemcomititans and TNFα) and low IL-6 producers (streptococcal strains and P. gingivalis). The expression of 4 miRNAs (miR-181-5p, -186-5p, -28-5p and -155-5p) differed statistically significantly (p < 0.001) between healthy HSMCs and AthSMCs in the low IL-6 producer group. According to multidimensional scaling, two gene expression clusters were seen: one in HSMCs and one AthSMCs.

CONCLUSIONS

Our results suggest that inactivated oral bacteria induce inflammation that is differently regulated in healthy and atherosclerotic SMCs.

Relationship between decayed teeth and metabolic syndrome: data from 4716 middle-aged male Japanese employees

Background

Epidemiological findings regarding the relationship between decayed teeth (DT) and metabolic syndrome (MetS) are scarce. We evaluated the relationship of DT with MetS, obesity, and MetS components in early middle-aged male Japanese employees.

Methods

We cross-sectionally analyzed dental and medical health checkup results from a total of 4716 participants aged 42 or 46 years. Logistic regression models were employed to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) after adjustment for age, breakfast consumption frequency, drinking habits, smoking status, and physical activity.

Results

Significant differences in the prevalence of MetS, obesity determined by body mass index, and the components of MetS between participating men with and without DT were detected (all P < 0.01). The adjusted OR of MetS was 1.41 (95% CI, 1.14–1.74) for those with 1 or 2 DT, and 1.66 (95% CI, 1.28–2.16) for those with ≥3 DT (P for trend = 0.01), and this significant relationship was observed even in those without periodontal pocket formation (P for trend = 0.03) or missing teeth (P for trend = 0.02). DT was significantly related to overweight/obesity and the MetS components of hypertension, dyslipidemia, and hyperglycemia, with adjusted ORs of 1.35 (95% CI, 1.19–1.53), 1.22 (95% CI, 1.07–1.39), 1.18 (95% CI, 1.03–1.34), and 1.33 (95% CI, 1.13–1.56), respectively. In addition, even in non-overweight/non-obese men, DT was found to be related to dyslipidemia and hyperglycemia, though with marginal significance (P < 0.05).

Conclusions

Our findings suggest that having DT is related to MetS in early middle-aged Japanese men directly and through obesity and is independent of health behaviors, periodontal condition, and tooth loss.

Oral bacterial DNA findings in pericardial fluid

Background

We recently reported that large amounts of oral bacterial DNA can be found in thrombus aspirates of myocardial infarction patients. Some case reports describe bacterial findings in pericardial fluid, mostly done with conventional culturing and a few with PCR; in purulent pericarditis, nevertheless, bacterial PCR has not been used as a diagnostic method before.

Objective

To find out whether bacterial DNA can be measured in the pericardial fluid and if it correlates with pathologic–anatomic findings linked to cardiovascular diseases.

Methods

Twenty-two pericardial aspirates were collected aseptically prior to forensic autopsy at Tampere University Hospital during 2009–2010. Of the autopsies, 10 (45.5%) were free of coronary artery disease (CAD), 7 (31.8%) had mild and 5 (22.7%) had severe CAD. Bacterial DNA amounts were determined using real-time quantitative PCR with specific primers and probes for all bacterial strains associated with endodontic disease (Streptococcus mitis group, Streptococcus anginosus group, Staphylococcus aureus/Staphylococcus epidermidis, Prevotella intermedia, Parvimonas micra) and periodontal disease (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, Fusobacterium nucleatus, and Dialister pneumosintes).

Results

Of 22 cases, 14 (63.6%) were positive for endodontic and 8 (36.4%) for periodontal-disease-associated bacteria. Only one case was positive for bacterial culturing. There was a statistically significant association between the relative amount of bacterial DNA in the pericardial fluid and the severity of CAD (p=0.035).

Conclusions

Oral bacterial DNA was detectable in pericardial fluid and an association between the severity of CAD and the total amount of bacterial DNA in pericardial fluid was found, suggesting that this kind of measurement might be useful for clinical purposes.

Colonisation of gingival epithelia by subgingival biofilms in vitro: role of "red complex" bacteria

OBJECTIVES

Biofilm formation on tooth surface results in colonisation and invasion of the juxtaposed gingival tissue, eliciting strong inflammatory responses that lead to periodontal disease. This in vitro study investigated the colonisation of human gingival multi-layered epithelium by multi-species subgingival biofilms, and evaluated the relative effects of the "red complex" species (Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola).

METHODS

The grown biofilm consisted of Fusobacterium nucleatum, Campylobacter rectus, Veillonella dispar, P. gingivalis, Prevotella intermedia, T. forsythia, T. denticola, Actinomyces oris, Streptococcus anginosus and Streptococcus oralis, or its variant lacking the "red complex". After 48h in co-culture with the gingival epithelia, the bacterial species in the biofilm were quantified, whereas their localisation on the cell surface was investigated by combining confocal-laser scanning microscopy (CLSM) and fluorescence in situ hybridisation (FISH), as well as by scanning electron microscopy (SEM).

RESULTS

Exclusion of the "red complex" quantitatively affected S. oralis, but not other species. The "red-complex" species were all able to colonise the gingival epithelial cells. A co-localisation trend was observed between P. gingivalis and T. denticola, as determined by FISH. However, in the absence of all three "red complex" bacteria from the biofilm, an immense colonisation of streptococci (potentially S. oralis) was observed on the gingival epithelia, as confirmed by both CLSM and SEM.

CONCLUSIONS

While the "red complex" species synergise in colonizing gingival epithelia, their absence from the biofilm enhances streptococcal colonisation. This antagonism with streptococci reveals that the "red complex" may regulate biofilm virulence, with potential implications in periodontal pathogenesis.

Molecular analysis of oral bacteria in dental biofilm and atherosclerotic plaques of patients with vascular disease

BACKGROUND

Oral bacteria have been detected in atherosclerotic plaques at a variable frequency; however, the connection between oral health and vascular and oral bacterial profiles of patients with vascular disease is not clearly established. The aim of this study was to evaluate the presence of oral bacterial DNA in the mouth and atherosclerotic plaques, in addition to assessing the patients' caries and periodontal disease history.

METHODS

Thirty samples of supragingival and subgingival plaque, saliva and atherosclerotic plaques of 13 patients with carotid stenosis or aortic aneurysm were evaluated, through real-time polymerase chain reaction, for the presence of Streptococcus mutans (SM), Prevotella intermedia (PI), Porphyromonas gingivalis (PG) and Treponema denticola (TD). All patients were submitted to oral examination using the DMFT (decayed, missing and filled teeth) and PSR (Periodontal Screening and Recording) indexes. Histopathological analysis of the atherosclerotic plaques was performed.

RESULTS

Most of the patients were edentulous (76.9%). SM, PI, PG and TD were detected in 100.0%, 92.0%, 15.3% and 30.7% of the oral samples, respectively. SM was the most prevalent targeted bacteria in atherosclerotic plaques, detected in 100% of the samples, followed by PI (7.1%). The vascular samples were negative for PG and TD. There was a statistically significant difference (p<0.05) between the presence of PG and TD in the oral cavity and vascular samples.

CONCLUSION

SM was found at a high frequency in oral and vascular samples, even in edentulous patients, and its presence in atherosclerotic plaques suggests the possible involvement of this bacterium in the disease progression.

Removable dental prostheses and cardiovascular survival: a 15-year follow-up study

OBJECTIVES

In previous studies, increasing number of teeth predicted better survival and the acute needs for dental treatment predicted mortality. We sought to investigate whether restored dentitions by various removable dental prostheses impact cardiovascular (CVD) longevity.

METHODS

Kuopio Oral Health and Heart study was initiated as a cross-sectional investigation with 256 subjects with diagnosed coronary artery disease [CAD] and 250 age- and sex-matched controls without CAD in 1995-1996. The mean age of both groups was 61, 30% were females. We appended mortality follow-up records to the baseline data and formulated this 15-year follow-up study. We examined the relationship between various types of dental prostheses and cardiovascular mortality by proportional hazard regression analyses. We also explored their correlation to oral and systemic inflammatory markers such as asymptotic dental score and C-reactive protein.

RESULTS

In a model adjusted for age, sex and smoking, groups having only natural teeth (NT), removable partial denture(s) [PD] and NT, a PD and a full denture [FD], and FD/FD or FD/NT demonstrated the following hazard ratios for mortality (95% confidence interval). NT both arches: 1.00 [reference]; PD and NT: 0.75 [0.22-2.56]; PD and FD: 1.99 [1.05-3.81]; and FD opposed by FD or NT: 1.71 [0.93-3.13], respectively [p for trend=0.05]. Although statistically not significant, those with PD and NT with mean a number of teeth [Nteeth] of 15.4 had better survival compared with those who had all NT [Nteeth=22.5]; while those who had FD and PD [Nteeth=6.5] had shorter longevity than those with FD/FD or FD/NT [Nteeth=3.5].

CONCLUSIONS

Although not all subgroups of dental prostheses reached significant relationship with CVD mortality, our study suggests that not only the number [quantity] of remaining teeth but their maintenance [quality] removing potential inflammatory foci, such as pericoronitis or retained root tips, may positively impact on cardiovascular survival.

Bacterial signatures in thrombus aspirates of patients with myocardial infarction

BACKGROUND

Infectious agents, especially bacteria and their components originating from the oral cavity or respiratory tract, have been suggested to contribute to inflammation in the coronary plaque, leading to rupture and the subsequent development of coronary thrombus. We aimed to measure bacterial DNA in thrombus aspirates of patients with ST-segment-elevation myocardial infarction and to check for a possible association between bacteria findings and oral pathology in the same cohort.

METHODS AND RESULTS

Thrombus aspirates and arterial blood from patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention (n=101; 76% male; mean age, 63.3 years) were analyzed with real-time quantitative polymerase chain reaction with specific primers and probes to detect bacterial DNA from several oral species and Chlamydia pneumoniae. The median value for the total amount of bacterial DNA in thrombi was 16 times higher than that found in their blood samples. Bacterial DNA typical for endodontic infection, mainly oral viridans streptococci, was measured in 78.2% of thrombi, and periodontal pathogens were measured in 34.7%. Bacteria-like structures were detected by transmission electron microscopy in all 9 thrombus samples analyzed; whole bacteria were detected in 3 of 9 cases. Monocyte/macrophage markers for bacteria recognition (CD14) and inflammation (CD68) were detected in thrombi (8 of 8) by immunohistochemistry. Among the subgroup of 30 patients with myocardial infarction examined by panoramic tomography, a significant association between the presence of periapical abscesses and oral viridans streptococci DNA-positive thrombi was found (odds ratio, 13.2; 95% confidence interval, 2.11-82.5; P=0.004).

CONCLUSIONS

Dental infection and oral bacteria, especially viridans streptococci, may be associated with the development of acute coronary thrombosis.

Potential involvement of collagen-binding proteins of Streptococcus mutans in infective endocarditis

OBJECTIVE

Streptococcus mutans, a major pathogen of dental caries, is considered to be one of the causative agents of infective endocarditis (IE). Two types of cell surface collagen-binding proteins, Cnm and Cbm, have been identified in the organism. The aim of the present study was to analyze these proteins as possible etiologic factors for IE.

MATERIALS AND METHODS

The binding activities of S. mutans strains to collagen types I, III, and IV were analyzed relative to the presence of Cnm and Cbm, as were their adhesion and invasion properties with human umbilical vein endothelial cells (HUVEC). In addition, distributions of the genes encoding Cnm and Cbm in S. mutans-positive heart valve specimens extirpated from IE and non-IE patients were analyzed by PCR.

RESULTS

Most of the Cbm-positive strains showed higher levels of binding to type I collagen as well as higher rates of adhesion and invasion with HUVEC as compared to the Cnm-positive strains. Furthermore, the gene encoding Cbm was detected significantly more frequently in heart valve specimens from IE patients than from non-IE patients.

CONCLUSIONS

These results suggest that the collagen-binding protein Cbm of S. mutans may be one of the potential important factor associated with the pathogenesis of IE.