Lipopolysaccharides from Porphyromonas endodontalis and Porphyromonas gingivalis promote angiogenesis via Toll-like-receptors 2 and 4 pathways in vitro

Associations between the oral microbiome, number of teeth and frailty among American adults: A cross-sectional study from NHANES 2009-2012

BACKGROUND

The intricate interrelationship between oral health, the number of teeth, oral microbiota, and frailty remains largely unexplored in clinical research. This study aimed to investigate the interrelationship between oral microbiome, the number of teeth, and frailty.

METHODS

Data from 4518 participants in NHANES 2009-2012 were analyzed. Frailty was measured using the 48-item Frailty Index (FI). Multivariable logistic regression and restricted cubic spline (RCS) evaluated associations between alpha diversity and frailty. Mediation analysis was used to assess the role of number of teeth. The associations between oral microbiome diveristy and mortality were analyzed by Cox regression. Beta diversity was examined with PCoA and PERMANOVA.

RESULTS

The prevalence of frailty was 39.73 %. Univariate analysis showed that alpha diversity indices except for the Simpson index were significantly lower in frailty, and after adjusted for confounders, observed ASVs (adjusted OR: 0.80 [0.73, 0.87], p < 0.001), Faith's PD (adjusted OR: 0.81 [0.74, 0.88], p < 0.001) and Shannon-Weiner index (adjusted OR: 0.88 [0.81, 0.95], p = 0.002) were remained significantly associated with frailty. The reduced number of teeth partially mediated the relationship (for Faith's PD: βindirect = -0.001 [-0.003, 0.000], p = 0.036, proportion: 8.33 % [0.00 %, 37.50 %]; for Shannon-Weiner index, βindirect = -0.007 [-0.013, -0.002], p = 0.007, Proportion = 17.07 % [3.39 %, 65.00 %]). Univariable Cox proportional hazard regression showed that all alpha diversity indices were significantly associated with all-cause mortality in frail population, and in multivariable analysis, Shannon-Weiner index (HR: 0.72 [0.55, 0.94], p = 0.017) and Simpson index (HR: 0.71 [0.60, 0.83], p < 0.001) remained statistically significant. PCoA showed that beta diversity was also significantly associated with frailty.

CONCLUSION

Lower oral microbiome diversity is associated with higher frailty and mortality. The number of teeth partially mediates this link, emphasizing the importance of oral health in mitigating frailty and promoting healthy aging.

Exploring the regulatory roles of MicroRNAs on NF- ΚB target genes in individuals with apical periodontitis

OBJECTIVES

This study investigated the association of miRNA-181-5p, miRNA-150-5p, miRNA-146a-5p, and miRNA-16-5p, and inflammatory genes linked to the NF-κB pathway in patients with symptomatic and asymptomatic apical periodontitis.

MATERIALS AND METHODS

A cross-sectional study was conducted involving apical tissues from asymptomatic apical periodontitis (AAP, n = 17), symptomatic apical periodontitis (SAP, n = 15), and healthy periodontal ligament (HPL, n = 16). Expression levels of miRNA-181-5p, miRNA-150-5p, miRNA-146a-5p, and miRNA-16-5p, along with mRNA levels of IL-6, VEGF-A, HIF-1α, and NF-κB, were quantified using qPCR. Data were analyzed through descriptive statistics and regression models, including mediation analysis conducted using STATA V14 (p < 0.05).

RESULTS

mRNA levels of IL-6, VEGF-A, and NF-κB were significantly higher in SAP compared to HPL (p < 0.05), while AAP did not show differences (p > 0.05). Also, no significant differences were observed in HIF-1α expression among the groups (p > 0.05). miRNA-181-5p, miRNA-16-5p, and miRNA-146a-5p were downregulated in both AAP and SAP, compared to HPL (p < 0.05), whereas miRNA-150-5p was upregulated (p < 0.05). Negative correlations were found between miRNA-181-5p and miRNA-16-5p with IL-6, and between miRNA-181-5p and VEGF-A in AP forms (p < 0.05). Mediation analysis revealed that the upregulation of IL-6 mRNA was mediated by miRNA-16-5p in SAP.

CONCLUSIONS

Apical periodontitis is associated with the downregulation of miRNA-181-5p, miRNA-16-5p, and miRNA-146a-5p and the upregulation of miRNA-150-5p. IL-6 mRNA levels seem to be regulated by miRNA-16-5p during SAP.

CLINICAL RELEVANCE

This study provides insights into the molecular mechanisms and the inflammatory response in apical periodontitis (AP), differentiating between asymptomatic (AAP) and symptomatic forms (SAP). By identifying the specific roles of miRNAs-particularly miRNA-181-5p, miRNA-150-5p, miRNA-146a-5p, and miRNA-16-5p-on inflammation-related genes via the NF-κB pathway, the findings highlight potential diagnostic and therapeutic targets. Notably, SAP is associated with downregulation of miRNA-181-5p, miRNA-16-5p, and miRNA-146a-5p, alongside upregulation of miRNA-150-5p. The study reveals that miRNA-16-5p may modulate IL-6 gene expression during SAP, which can exacerbate inflammation and osteoclastogenesis in the affected tissues. Understanding the gene regulation of inflammatory mediators in AP can aid clinicians in personalizing management approaches, particularly in cases where traditional diagnostic methods fall short. This molecular perspective may also pave the way for miRNA-based interventions, enhancing patient outcomes by specifically targeting the inflammatory pathways underlying AP pathology.

P. Gingivalis induce macrophage polarization by regulating hepcidin expression in chronic apical periodontitis

INTRODUCTION

Hepcidin, a central regulatory molecule of iron metabolism, is upregulated through the IL-6/STAT3 signaling pathway in inflammatory and infectious states, contributing to the pathogenesis of various diseases. In chronic apical periodontitis (CAP), Porphyromonas gingivalis (P. gingivalis) and its lipopolysaccharides (LPS) activate various immune responses in vivo, contributing to disease progression. This study evaluated the role and mechanism of hepcidin in P. gingivalis-induced bone tissue damage in CAP, focusing on its promotion of macrophage M1 polarization via the IL-6/STAT3 signaling pathway.

METHODS

We analyzed a GSE77459 dataset from the GEO database, containing data from inflammatory and normal dental pulp tissues. RT-qPCR and immunofluorescence staining were used to detect the expression of hepcidin in human CAP tissues and its relationship with macrophages. Mouse bone marrow derived macrophages (BMDMs) were cultured in vitro and stimulated with P. gingivalis LPS. The effects of Stattic on macrophage hepcidin expression, IL-6 expression, STAT3 phosphorylation, and macrophage polarization were detected by ELISA, western blotting, RT-qPCR, and flow cytometry, respectively.

RESULTS

Hepcidin expression in human inflammatory dental pulp tissues was upregulated via the IL-6/STAT3 pathway and correlated with macrophage polarization. Hepcidin-encoding genes were found to be highly expressed and primarily associated with M1 macrophages in CAP tissues. In vitro experiments revealed that P. gingivalis LPS stimulation induced macrophages to express hepcidin through the IL-6/STAT3 pathway and polarize to M1. Additionally, the IL-6/STAT3 pathway inhibitor Stattic suppressed these changes.

CONCLUSIONS

Our study demonstrates that in CAP, macrophages highly express hepcidin, which subsequently alters macrophage metabolism, regulates M1 polarization, and leads to bone tissue destruction.

The immune landscape in apical periodontitis: From mechanism to therapy

Apical periodontitis (AP) is featured by a persistent inflammatory response and alveolar bone resorption initiated by microorganisms, posing risks to both dental and systemic health. Nonsurgical endodontic treatment is the recommended treatment plan for AP with a high success rate, but in some cases, periapical lesions may persist despite standard endodontic treatment. Better comprehension of the AP inflammatory microenvironment can help develop adjunct therapies to improve the outcome of endodontic treatment. This review presents an overview of the immune landscape in AP, elucidating how microbial invasion triggers host immune activation and shapes the inflammatory microenvironment, ultimately impacting bone homeostasis. The destructive effect of excessive immune activation on periapical tissues is emphasized. This review aimed to systematically discuss the immunological basis of AP, the inflammatory bone resorption and the immune cell network in AP, thereby providing insights into potential immunotherapeutic strategies such as targeted therapy, antioxidant therapy, adoptive cell therapy and cytokine therapy to mitigate AP-associated tissue destruction.

The role of the gut microbiota in tumor, immunity, and immunotherapy

In recent years, with the deepening understanding of the gut microbiota, it has been recognized to play a significant role in the development and progression of diseases. Particularly in gastrointestinal tumors, the gut microbiota influences tumor growth by dysbiosis, release of bacterial toxins, and modulation of host signaling pathways and immune status. Immune checkpoint inhibitors (ICIs) have greatly improved cancer treatment efficacy by enhancing immune cell responses. Current clinical and preclinical studies have demonstrated that the gut microbiota and its metabolites can enhance the effectiveness of immunotherapy. Furthermore, certain gut microbiota can serve as biomarkers for predicting immunotherapy responses. Interventions targeting the gut microbiota for the treatment of gastrointestinal diseases, especially colorectal cancer (CRC), include fecal microbiota transplantation, probiotics, prebiotics, engineered bacteria, and dietary interventions. These approaches not only improve the efficacy of ICIs but also hold promise for enhancing immunotherapy outcomes. In this review, we primarily discuss the role of the gut microbiota and its metabolites in tumors, host immunity, and immunotherapy.

Inducing cyclooxygenase-2 expression, prostaglandin E2 and prostaglandin F2α production of human dental pulp cells by activation of toll-like receptor-3, mitogen-activated protein kinase kinase/extracellular signal-regulated kinase and p38 signaling

Background/purpose

Bacterial infection was the major etiology for pulpal/root canal infection. This study aimed to investigate the activation of toll-like receptor-3 (TLR) on cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) and PGF2α production of human dental pulp cells (HDPCs) and associated signaling.

Materials and methods

HDPCs were exposed to different concentrations of Poly (I:C) (a TLR3 activator). Cell viability was determined by 3- (4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay and alkaline phosphatase (ALP) activity was evaluated by ALP staining. Activation of extracellular signal-regulated kinase (ERK) and p38 by Poly (I:C) was determined by immunofluorescent staining. The COX-2 protein expression was analyzed by Western blot. PGE2 and PGF2α production was measured by enzyme-linked immunosorbent assay. The mRNA expression was studied by real-time polymerase-chain reaction. Moreover, HDPCs were exposed to Poly(I:C) with/without U0126 or SB203580 treatment and analysis of COX-2 expression and prostanoid production were conducted.

Results

Poly (I:C) showed little effect on ALP activity, but decreased viability of HDPCs. It stimulated COX-2 mRNA and protein expression. Poly (I:C) induced PGE2 and PGF2α production of HDPCs. Poly (I:C) activated p-ERK, and p-p38 protein expression. Treatment by U0126 (a mitogen-activated protein kinase kinase (MEK)/ERK inhibitor) and SB203580 (a p38 inhibitor) attenuated Poly (I:C)-induced COX-2 mRNA and protein expression as well as PGE2 and PGF2α production.

Conclusion

TLR3 activation is involved in the infection and inflammatory responses of pulp tissues, via MEK/ERK, and p38 signaling to mediate COX-2 expression as well as PGE2 and PGF2α production, contributing to the pathogenesis and progression of pulpal/periapical diseases.

Ameliorative Effect of Ginsenoside Rg6 in Periodontal Tissue Inflammation and Recovering Damaged Alveolar Bone

Periodontal disease is a chronic disease with a high prevalence, and in order to secure natural materials to prevent oral diseases, new materials that protect periodontal tissue from inflammation are being sought. Genes were identified using real-time quantitative polymerase chain reaction (RT-qPCR), and proteins were confirmed using Western blot. Dichlorodihydrofluorescein diacetate (DCF-DA) analysis was used, and the antibacterial effects were confirmed through Minimum Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) analysis. To confirm this effect in vivo, Sprague-Dawley rats, in which periodontitis was induced using ligation or Lipopolysaccharide of Porphyromonas gingivalis (PG-LPS), were used. In vitro experiments using human periodontal ligament (HPDL) cells stimulated with PG-LPS showed that Ginsenoside Rg6 (G-Rg6) had anti-inflammatory, antibacterial, antioxidant, and osteoblast differentiation properties. In vivo, G-Rg6 was effective in Sprague-Dawley rats in which periodontitis was induced using ligation or PG-LPS. Therefore, Ginsenoside Rg6 shows potential effectiveness in alleviating periodontitis.

Therapeutic effect of Echinococcus granulosus cyst fluid on bacterial sepsis in mice

BACKGROUND

The primary pathophysiological process of sepsis is to stimulate a massive release of inflammatory mediators to trigger systemic inflammatory response syndrome (SIRS), the major cause of multi-organ dysfunction and death. Like other helminths, Echinococcus granulosus induces host immunomodulation. We sought to determine whether E. granulosus cyst fluid (EgCF) displays a therapeutic effect on sepsis-induced inflammation and tissue damage in a mouse model.

METHODS

The anti-inflammatory effects of EgCF were determined by in vitro culture with bone marrow-derived macrophages (BMDMs) and in vivo treatment of BALB/C mice with cecal ligation and puncture (CLP)-induced sepsis. The macrophage phenotypes were determined by flow cytometry, and the levels of cytokines in cell supernatants or in sera of mice were measured (ELISA). The therapeutic effect of EgCF on sepsis was evaluated by observing the survival rates of mice for 72 h after CLP, and the pathological injury to the liver, kidney, and lung was measured under a microscope. The expression of TLR-2/MyD88 in tissues was measured by western blot to determine whether TLR-2/MyD88 is involved in the sepsis-induced inflammatory signaling pathway.

RESULTS

In vitro culture with BMDMs showed that EgCF promoted macrophage polarization to M2 type and inhibited lipopolysaccharide (LPS)-induced M1 macrophages. EgCF treatment provided significant therapeutic effects on CLP-induced sepsis in mice, with increased survival rates and alleviation of tissue injury. The EgCF conferred therapeutic efficacy was associated with upregulated anti-inflammatory cytokines (IL-10 and TGF-β) and reduced pro-inflammatory cytokines (TNF-α and INF-γ). Treatment with EgCF induced Arg-1-expressed M2, and inhibited iNOS-expressed M1 macrophages. The expression of TLR-2 and MyD88 in EgCF-treated mice was reduced.

CONCLUSIONS

The results demonstrated that EgCF confers a therapeutic effect on sepsis by inhibiting the production of pro-inflammatory cytokines and inducing regulatory cytokines. The anti-inflammatory effect of EgCF is carried out possibly through inducing macrophage polarization from pro-inflammatory M1 to regulatory M2 phenotype to reduce excessive inflammation of sepsis and subsequent multi-organ damage. The role of EgCF in regulating macrophage polarization may be achieved by inhibiting the TLR2/MyD88 signaling pathway.

Hispidulin Inhibits the Vascular Inflammation Triggered by Porphyromonas gingivalis Lipopolysaccharide

Hispidulin is a natural bioactive flavonoid that has been studied for its potential therapeutic properties, including its anti-inflammatory, antioxidant, and neuroprotective effects. The aim of this study was to explore whether hispidulin could inhibit the endothelial inflammation triggered by Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS). The adhesion of monocytes to the vascular endothelium was evaluated through in vitro and ex vivo monocyte adhesion assays. We analyzed the migration of monocytes across the endothelial layer using a transmigration assay. The results showed that treatment with hispidulin decreased the P. gingivalis LPS-induced adhesion of monocytes to endothelial cells and their migration by suppressing the P. gingivalis LPS-triggered expression of intercellular adhesion molecule-1 (ICAM-1) through downregulating nuclear factor-қB (NF-қB). In addition, hispidulin inhibited P. gingivalis LPS-induced mitogen-activated protein kinases (MAPKs) and AKT in endothelial cells. Altogether, the results indicate that hispidulin suppresses the vascular inflammation induced by P. gingivalis LPS. Mechanistically, it prevents the adhesion of monocytes to the vascular endothelium and migration and inhibits NF-қB, MAPKs, and AKT signaling in endothelial cells.