Experimental Periodontitis Deteriorated Atherosclerosis Associated With Trimethylamine N-Oxide Metabolism in Mice

Nonsurgical periodontal treatment improved the abnormal trimethylamine n-oxide metabolism in Apoe-/- mice with periodontitis

BACKGROUND AND AIMS

Periodontitis aggravated atherosclerosis and the plasma level of the atherosclerosis virulence factor trimethylamine n-oxide (TMAO) increased in Apoe-/- mice was reported. Nonsurgical periodontal treatment (NSPT) is an important treatment method for periodontitis. Therefore, we investigate how NSPT ameliorates the metabolism of TMAO in Apoe-/- mice with periodontitis.

METHODS

Six-week-old Apoe-/- mice were randomly divided into three groups: the control group (no treatment), the LIGPG (ligation with silk threads soaked in Porphyromonas gingivalis) group, and the NSPT group (removing the ligature thread and scaling). Quantifications of TMAO in plasma were performed. Mouse maxillae were scanned using micro-CT to measure alveolar bone absorption. Livers and intestines were analyzed for gene and protein expression. Mouse feces at 0 and 8 weeks were collected and further analyzed using 16S rRNA gene sequencing for gut microbiota.

RESULTS

The TMAO concentration in the NSPT group was significantly lower than that in the LIGPG group. The systemic inflammatory environment caused by periodontitis was improved through NSPT, especially in the small intestine. The composition and abundance of the intestinal microflora changed after treatment. Spearman correlation analysis between TMAO and different bacteria revealed that plasma TMAO levels were significantly positively correlated with Bacteroides, Helicobacter, Lachnoclostridium and Lactobacillus and significantly negatively correlated with Parasutterella and Ileibacterium.

CONCLUSIONS

NSPT alleviated the periodontitis-induced increase in TMAO levels, which might be associated with changes in the intestinal microbiota, especially Bacteroides, Helicobacter, Lachnoclostridium, Lactobacillus, Parasutterella and Ileibacterium. Our study provides new insights for the study of NSPT and cardiovascular diseases.

Salivary trimethylamine N-oxide: a novel non-invasive marker for periodontal inflammation

OBJECTIVES

Trimethylamine N-oxide (TMAO) has been implicated in systemic inflammatory pathways, emphasizing its potential as a biomarker. Elevated plasma TMAO levels have been associated with increased oxidative stress, leading to higher plasma concentrations of TNF-α, a key pro-inflammatory cytokine. Given this systemic inflammatory linkage, saliva-a non-invasive diagnostic medium-offers a unique opportunity to reflect both local and systemic inflammatory changes. This study aimed to evaluate the alterations in salivary and serum TMAO levels in periodontitis and assess the diagnostic potential of salivary TMAO as an indicator of periodontal inflammation.

MATERIALS AND METHODS

Twenty-four patients with periodontitis (Stage III Grade B) and 24 healthy controls were included. Clinical parameters (probing depth (PD), plaque index (PI), bleeding on probing (BOP), and clinical attachment loss (CAL)) were recorded. TMAO levels in saliva and serum were measured using liquid chromatography-mass spectrometry (LC-MS/MS), and TNF-α levels were assessed using Enzyme-Linked ImmunoSorbent Assay (ELISA).

RESULTS

Salivary and serum TMAO levels and salivary TNF-α levels were significantly higher in the periodontitis group (p = 0.003, p = 0.004, and p = 0.031, respectively). Salivary TMAO showed positive correlations with periodontal parameters (p < 0.05) and salivary TNF-α levels. A significant positive correlation was also observed between salivary and serum TMAO levels (p < 0.001). Salivary TMAO was the accurate biomarker in differentiating between periodontitis and controls (sensitivity = 0.583, specificity = 0.833, AUC = 0.747).

CONCLUSIONS

Salivary TMAO demonstrates potential as a non-invasive marker for periodontitis, showing correlations with clinical parameters and inflammatory markers. These findings suggest that TMAO may reflect both local and systemic inflammatory states associated with periodontal disease.

CLINICAL RELEVANCE

Salivary TMAO may serve as a potential non-invasive indicator of periodontitis, as it reflects aspects of both local and systemic inflammation, offering insights into periodontal disease status.

Trimethylamine N-Oxide (TMAO) and TNF-α Levels in Periodontal Disease Associated With Smoking

AIMS

Trimethylamine N-oxide (TMAO) is a compound involved in the pathogenesis of various systemic inflammatory diseases, including cardiovascular conditions. The aim of this study was to determine differences in saliva and serum levels of TMAO between periodontitis and healthy patients according to smoking status.

METHODS

The study included four systemically healthy groups: periodontally healthy non-smokers (NS-Control; n = 25), non-smokers with Stage-III-Grade-B periodontitis (NS-Periodontitis; n = 25), periodontally healthy smokers (S-Control; n = 25), and smokers with Stage-III Grade-C periodontitis (S-Periodontitis; n = 25). Periodontal parameters were recorded. TMAO levels were determined in saliva and serum samples using liquid chromatography-mass spectrometry (LC-MS/MS). TNF-α levels were measured by the ELISA method.

RESULTS

Salivary TNF-α and TMAO levels were significantly elevated in the smoking periodontitis group compared to other groups (p < 0.001 and p = 0.003, respectively). Serum TMAO levels were also significantly higher in the smoking periodontitis group compared to non-smoking controls and non-smoking periodontitis. TMAO/SFR ratios were notably higher in the smoking periodontitis group compared to other groups, and a strong positive correlation was observed between salivary TMAO and TNF-α levels (r = 0.892, p < 0.001).

CONCLUSION

The data suggested that TMAO and TNF-α are associated with inflammatory mechanisms of periodontitis in cases where periodontitis coexists with smoking.

TRIAL REGISTRATION

NCT06580431.

The oral-gut microbiota axis: a link in cardiometabolic diseases

The oral-gut microbiota axis plays a crucial role in cardiometabolic health. This review explores the interactions between these microbiomes through enteric, hematogenous, and immune pathways, resulting in disruptions in microbial balance and metabolic processes. These disruptions contribute to systemic inflammation, metabolic disorders, and endothelial dysfunction, which are closely associated with cardiometabolic diseases. Understanding these interactions provides insights for innovative therapeutic strategies to prevent and manage cardiometabolic diseases.

Crosstalk between periodontitis and cardiovascular risk

Recent demographic developments resulted in an aged society with a rising disease burden of systemic and non-communicable diseases (NCDs). In cardiovascular disease (CVD), a NCD with high morbidity and mortality, recent preventive strategies include the investigation of comorbidities to reduce its significant economic burden. Periodontal disease, an oral bacterial-induced inflammatory disease of tooth-supporting tissue, is regulated in its prevalence and severity by the individual host response to a dysbiotic oral microbiota. Clinically, both NCDs are highly associated; however, shared risk factors such as smoking, obesity, type II diabetes mellitus and chronic stress represent only an insufficient explanation for the multifaceted interactions of both disease entities. Specifically, the crosstalk between both diseases is not yet fully understood. This review summarizes current knowledge on the clinical association of periodontitis and CVD, and elaborates on how periodontitis-induced pathophysiological mechanisms in patients may contribute to increased cardiovascular risk with focus on atherosclerosis. Clinical implications as well as current and future therapy considerations are discussed. Overall, this review supports novel scientific endeavors aiming at improving the quality of life with a comprehensive and integrated approach to improve well-being of the aging populations worldwide.

The Oral-Gut-Brain Axis: The Influence of Microbes as a Link of Periodontitis With Ischemic Stroke

Periodontitis, a non-communicable chronic inflammation disease resulting from dysbiosis of the oral microbiota, has been demonstrated to have a positive association with the risk of ischemic stroke (IS). The major periodontal pathogens contribute to the progression of stroke-related risk factors such as obesity, diabetes, atherosclerosis, and hypertension. Transcriptional changes in periodontitis pathogens have been detected in oral samples from stroke patients, suggesting a new conceptual framework involving microorganisms. The bidirectional regulation between the gut and the central nervous system (CNS) is mediated by interactions between intestinal microflora and brain cells. The connection between the oral cavity and gut through microbiota indicates that the oral microbial community may play a role in mediating complex communication between the oral cavity and the CNS; however, underlying mechanisms have yet to be fully understood. In this review, we present an overview of key concepts and potential mechanisms of interaction between the oral-gut-brain axis based on previous research, focusing on how the oral microbiome (especially the periodontal pathogens) impacts IS and its risk factors, as well as the mediating role of immune system homeostasis, and providing potential preventive and therapeutic approaches.

Exosomal miR-155-5p promote the occurrence of carotid atherosclerosis

Periodontitis is a significant independent risk factor for atherosclerosis. Yet, the exact mechanism of action is still not fully understood. In this study, we investigated the effect of exosomes-miR-155-5p derived from periodontal endothelial cells on atherosclerosis in vitro and in vivo. Higher expression of miR-155-5p was detected in the plasma exosomes of patients with chronic periodontitis (CP) and carotid atherosclerosis (CAS) compared to patients with CP. Also, the expression level of miR-155-5p was associated with the severity of CP. miR-155-5p-enriched exosomes from HUVECs increased the angiogenesis and permeability of HAECs and promoted the expression of angiogenesis, permeability, and inflammation genes. Along with the overexpression or inhibition of miR-155-5p, the biological effect of HUVECs-derived exosomes on HAECs changed correspondingly. In ApoE-/- mouse models, miR-155-5p-enriched exosomes promoted the occurrence of carotid atherosclerosis by increasing permeable and angiogenic activity. Collectively, these findings highlight a molecular mechanism of periodontitis in CAS, uncovering exosomal miR-155-5p derived periodontitis affecting carotid endothelial cells in an 'exosomecrine' manner. Exosomal miR-155-5p may be used as a biomarker and target for clinical intervention to control this intractable disease in future, and the graphic abstract was shown in Figure S1.

(Poly)phenol-rich grape and blueberry extract prevents LPS-induced disruption of the blood-brain barrier through the modulation of the gut microbiota-derived uremic toxins

The dynamic protective capacity of (poly)phenols, attributed to their potent antioxidant and anti-inflammatory properties, has been consistently reported. Due to their capacity to alter gut microbiome composition, further actions of (poly)phenols may be exerted through the modulation of the microbiota-gut-brain axis. However, the underlying mechanisms remain poorly defined. Here, we investigated the protective effect of a (poly)phenol-rich grape and blueberry extract (Memophenol™), on the microbiota-gut-brain axis in a model of chronic low-grade inflammation (0.5 mg/kg/wk lipopolysaccharide (LPS) for 8 weeks). Dietary supplementation of male C57BL/6 J mice with Memophenol™ prevented LPS-induced increases in the microbe-derived uremia-associated molecules, indoxyl sulfate (IS) and trimethylamine N-oxide (TMAO). These changes coincided with shifts in gut microbiome composition, notably Romboutsia and Desulfovibrio abundance, respectively. In the brain, LPS exposure disrupted the marginal localisation of the endothelial tight junction ZO-1 and downregulated ZO-1 mRNA expression to an extent closely correlated with TMAO and IS levels; a process prevented by Memophenol™ intake. Hippocampal mRNA sequencing analysis revealed significant downregulation in regulatory pathways of neurodegeneration with Memophenol™ intake. These findings may indicate a novel protective role of the (poly)phenol-rich grape and blueberry extract on the endothelial tight junction component ZO-1, acting through modulation of gut microbial metabolism.

Periodontitis impacts on thrombotic diseases: from clinical aspect to future therapeutic approaches

Periodontitis is a chronic inflammatory disease initiated by biofilm microorganisms and mediated by host immune imbalance. Uncontrolled periodontal infections are the leading cause of tooth loss in adults. Thrombotic diseases can lead to partial or complete obstruction of blood flow in the circulatory system, manifesting as organ or tissue ischemia and necrosis in patients with arterial thrombosis, and local edema, pain and circulatory instability in patients with venous thrombosis, which may lead to mortality or fatality in severe case. Recent studies found that periodontitis might enhance thrombosis through bacterial transmission or systemic inflammation by affecting platelet-immune cell interactions, as well as the coagulation, and periodontal therapy could have a prophylactic effect on patients with thrombotic diseases. In this review, we summarized clinical findings on the association between periodontitis and thrombotic diseases and discussed several novel prothrombotic periodontitis-related agents, and presented a perspective to emphasize the necessity of oral health management for people at high risk of thrombosis.

Low-Molecular-Weight Compounds Produced by the Intestinal Microbiota and Cardiovascular Disease

Cardiovascular disease is the main cause of mortality in industrialized countries, with over 500 million people affected worldwide. In this work, the roles of low-molecular-weight metabolites originating from the gut microbiome, such as short-chain fatty acids, hydrogen sulfide, trimethylamine, phenylacetic acid, secondary bile acids, indoles, different gases, neurotransmitters, vitamins, and complex lipids, are discussed in relation to their CVD-promoting or preventing activities. Molecules of mixed microbial and human hepatic origin, such as trimethylamine N-oxide and phenylacetylglutamine, are also presented. Finally, dietary agents with cardioprotective effects, such as probiotics, prebiotics, mono- and poly-unsaturated fatty acids, carotenoids, and polyphenols, are also discussed. A special emphasis is given to their gut microbiota-modulating properties.

Effect of three oral pathogens on the TMA-TMAO metabolic pathway

Background

Trimethylamine-N-oxide (TMAO) is produced by hepatic flavin-containing monooxygenase 3 (FMO3) from trimethylamine (TMA). High TMAO level is a biomarker of cardiovascular diseases and metabolic disorders, and it also affects periodontitis through interactions with the gastrointestinal microbiome. While recent findings indicate that periodontitis may alter systemic TMAO levels, the specific mechanisms linking these changes and particular oral pathogens require further clarification.

Methods

In this study, we established a C57BL/6J male mouse model by orally administering Porphyromonas gingivalis (P. gingivalis, Pg), Fusobacterium nucleatum (F. nucleatum, Fn), Streptococcus mutans (S. mutans, Sm) and PBS was used as a control. We conducted LC-MS/MS analysis to quantify the concentrations of TMAO and its precursors in the plasma and cecal contents of mice. The diversity and composition of the gut microbiome were analyzed using 16S rRNA sequencing. TMAO-related lipid metabolism and enzymes in the intestines and liver were assessed by qPCR and ELISA methods. We further explored the effect of Pg on FMO3 expression and lipid molecules in HepG2 cells by stimulating the cells with Pg-LPS in vitro.

Results

The three oral pathogenic bacteria were orally administered to the mice for 5 weeks. The Pg group showed a marked increase in plasma TMAO, betaine, and creatinine levels, whereas no significant differences were observed in the gut TMAO level among the four groups. Further analysis showed similar diversity and composition in the gut microbiomes of both the Pg and Fn groups, which were different from the Sm and control groups. The profiles of TMA-TMAO pathway-related genera and gut enzymes were not significantly different among all groups. The Pg group showed significantly higher liver FMO3 levels and elevated lipid factors (IL-6, TG, TC, and NEFA) in contrast to the other groups. In vitro experiments confirmed that stimulation of HepG2 cells with Pg-LPS upregulated the expression of FMO3 and increased the lipid factors TC, TG, and IL-6.

Conclusion

This study conclusively demonstrates that Pg, compared to Fn and Sm, plays a critical role in elevating plasma TMAO levels and significantly influences the TMA-TMAO pathway, primarily by modulating the expression of hepatic FMO3 and directly impacting hepatic lipid metabolism.

Potential Association of the Oral Microbiome with Trimethylamine N-Oxide Quantification in Mexican Patients with Myocardial Infarction

Many attempts have been proposed to evaluate the linkage between the oral-gut-liver axis and the mechanisms related to the diseases' establishment. One of them is the oral microbiota translocation into the bloodstream, liver, and gut, promoting a host dysbiosis and triggering the presence of some metabolites such as trimethylamine N-oxide (TMAO), known as a risk marker for cardiovascular disease, and especially the myocardial infarction (MI). In the present pilot study, the involvement of oral dysbiosis related to the presence of TMAO has been considered an independent component of the standard risk factors (SRs) in the development of MI, which has not been previously described in human cohorts. A positive and significant correlation of TMAO levels with Porphyromonas was identified; likewise, the increase of the genus Peptidiphaga in patients without SRs was observed. We determined that the presence of SRs does not influence the TMAO concentration in these patients. This report is the first study where the relationship between oral dysbiosis and TMAO is specified in the Mexican population. Our findings provide information on the possible contribution of the oral pathogens associated with gut dysbiosis in the development of MI, although further analysis should be performed.

[Periodontitis : An underestimated risk of cardiovascular diseases]

Epidemiological studies have identified periodontitis as a contributing factor to cardiovascular risk. Periodontitis is a chronic inflammatory disease that affects the tissues supporting the teeth. Although the nature of the association between periodontitis and cardiovascular disease (CVD) remains to be defined, the low-grade systemic inflammation and chronic bacteremia associated with periodontitis appear to be involved in the development of atherosclerosis and associated cardiovascular pathologies. Periodontal treatment has been shown to improve cardiovascular health parameters. A bidirectional preventive approach, involving the management of both periodontitis and cardiovascular risk factors, could lead to a reduction in morbidity and mortality related to cardiovascular disease.

Periodontitis and atherosclerotic cardiovascular disease: A critical appraisal

In spite of intensive research efforts driving spectacular advances in terms of prevention and treatments, cardiovascular diseases (CVDs) remain a leading health burden, accounting for 32% of all deaths (World Health Organization. "Cardiovascular Diseases (CVDs)." WHO, February 1, 2017, https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds)). Cardiovascular diseases are a group of disorders affecting the heart and blood vessels. They encompass a collection of different conditions, among which atherosclerotic cardiovascular disease (ASCVD) is the most prevalent. CVDs caused by atherosclerosis, that is, ASCVD, are particularly fatal: with heart attack and stroke being together the most prevalent cause of death in the world. To reduce the health burden represented by ASCVD, it is urgent to identify the nature of the "residual risk," beyond the established risk factors (e.g., hypertension) and behavioral factors already maximally targeted by drugs and public health campaigns. Remarkably, periodontitis is increasingly recognized as an independent cardiovascular risk factor.

Association between Periodontal Disease and Arteriosclerosis-Related Diseases

Periodontitis, a major inflammatory disease of the oral cavity that can cause low-grade systemic inflammation, has been suggested to influence the development of comorbidities. Multiple systemic inflammatory mechanisms are common in the development of periodontal disease and atherosclerosis. Observational studies conducted worldwide have reported that periodontal disease may independently influence the progression of atherosclerotic disease. However, there is still insufficient evidence to demonstrate the causal relationship. This review describes the association between periodontal disease and arteriosclerosis-related diseases with the latest findings.

Unexpected lower level of oral periodontal pathogens in patients with high numbers of systemic diseases

Background

Periodontal disease is associated with systemic conditions such as diabetes, arthritis, and cardiovascular disease, all diseases with large inflammatory components. Some, but not all, reports show periopathogens Porphyromonas gingivialis and Tannerella forsythia at higher levels orally in people with one of these chronic diseases and in people with more severe cases. These oral pathogens are thought to be positively associated with systemic inflammatory diseases through induction of oral inflammation that works to distort systemic inflammation or by directly inducing inflammation at distal sites in the body. This study aimed to determine if, among patients with severe periodontal disease, those with multi-morbidity (or many chronic diseases) showed higher levels of periodontal pathogens.

Methods

A total of 201 adult subjects, including 84 with severe periodontal disease were recruited between 1/2017 and 6/2019 at a city dental clinic. Electronic charts supplied self-reported diseases and conditions which informed a morbidity index based on the number of chronic diseases and conditions present. Salivary composition was determined by 16S rRNA gene sequencing.

Results

As expected, patients with severe periodontal disease showed higher levels of periodontal pathogens in their saliva. Also, those with severe periodontal disease showed higher levels of multiple chronic diseases (multimorbidity). An examination of the 84 patients with severe periodontal disease revealed some subjects despite being of advanced age were free or nearly free of systemic disease. Surprisingly, the salivary microbiota of the least healthy of these 84 subjects, defined here as those with maximal multimorbidity, showed significantly lower relative numbers of periodontal pathogens, including Porphyromonas gingivalis and Tannerella Forsythia, after controlling for active caries, tobacco usage, age, and gender. Analysis of a control group with none to moderate periodontal disease revealed no association of multimorbidity or numbers of medications used and specific oral bacteria, indicating the importance of severe periodontal disease as a variable of interest.

Conclusion

The hypothesis that periodontal disease patients with higher levels of multimorbidity would have higher levels of oral periodontal pathogens is false. Multimorbidity is associated with a reduced relative number of periodontal pathogens Porphyromonas gingivalis and Tannerella forsythia.

Gut microbiota-dependent trimethylamine n-oxide pathway contributes to the bidirectional relationship between intestinal inflammation and periodontitis

Background

Intestinal inflammation and periodontitis influence the development of each other through the bidirectional relationship. As the intestinal microbiome metabolite, trimethylamine-N-oxide (TMAO) could contribute to chronic inflammation in the gut by influencing the gut microbial composition and intestinal immunity. Increased circulating TMAO levels often accompany clinical findings in patients with experimental periodontitis. However, the role of TMAO in the bidirectional relationship between intestinal inflammation and periodontitis remains unclear. Thus, we explored whether TMAO influences the periodontitis process by affecting intestinal immunity and microbial composition in this article.

Methods

Periodontitis was induced by unilateral ligation of the first molar in mice, and 3,3-dimethyl-1-butanol (DMB) was used as an inhibitor to reduce TMAO circulating. Twenty-five BALB/c mice were randomly assigned to five study sets (n = 5/group): no periodontitis with DMB (Control group), periodontitis (P) group, periodontitis with TMAO (P+TMAO) group, periodontitis with TMAO and DMB (P+TMAO+DMB) group, and periodontitis with DMB (P+DMB) group. The effect of TMAO was determined by assessing changes in intestinal histology, intestinal flora composition, periodontal tissue, and periodontal pro-inflammatory factors at ten days.

Results

The outcomes indicated a marked improvement in the intestinal inflammation severity, and intestinal flora diversity was reduced. Firmicutes number and the ratio of Firmicutes/Bacteroidetes were improved in the P+TMAO group. In addition, the alveolar bone resorption and the degree of periodontal tissue inflammation were more severe in the P+TMAO group than in other groups. Immunohistochemistry showed higher levels of TGF-β and IL-1β expression in the periodontal tissues of P+TMAO.

Conclusions

Our data suggest that TMAO could influence periodontal immunity and promote periodontal inflammation by affecting the intestinal microenvironment, revealing TMAO may affect the development of periodontitis through the bidirectional relationship of the oral-gut axis.

The effect of the "Oral-Gut" axis on periodontitis in inflammatory bowel disease: A review of microbe and immune mechanism associations

Periodontitis and inflammatory bowel diseases (IBD) are inflammatory diseases of the gastrointestinal tract that share common features of microbial-induced ecological dysregulation and host immune inflammatory response. The close relationship between periodontitis and IBD is characterized by a higher prevalence of IBD in patients with periodontitis and a higher prevalence and severity of periodontitis in patients with IBD, indicating that periodontitis and IBD are different from the traditional independent diseases and form an "Oral-Gut" axis between the two, which affect each other and thus form a vicious circle. However, the specific mechanisms leading to the association between the two are not fully understood. In this article, we describe the interconnection between periodontitis and IBD in terms of microbial pathogenesis and immune dysregulation, including the ectopic colonization of the gut by pathogenic bacteria associated with periodontitis that promotes inflammation in the gut by activating the host immune response, and the alteration of the oral microbiota due to IBD that affects the periodontal inflammatory response. Among the microbial factors, pathogenic bacteria such as Klebsiella, Porphyromonas gingivalis and Fusobacterium nucleatum may act as the microbial bridge between periodontitis and IBD, while among the immune mechanisms, Th17 cell responses and the secreted pro-inflammatory factors IL-1β, IL-6 and TNF-α play a key role in the development of both diseases. This suggests that in future studies, we can look for targets in the "Oral-Gut" axis to control and intervene in periodontal inflammation by regulating periodontal or intestinal flora through immunological methods.