Current understanding of periodontal disease pathogenesis and targets for host-modulation therapy

ENTR1 regulates periodontitis by modulating macrophage M1 polarization via AMPK activation

AIMS

Periodontitis is a chronic inflammatory disorder arising from an imbalance between oral microbiota and the host's immune response, with macrophages as pivotal targets for prevention and treatment. Endosome-associated Trafficking Regulator 1 (ENTR1) is indispensable for protein trafficking and implant osseointegration. However, its specific role in periodontitis has yet to be clarified. This research seeks to explore the effects of ENTR1 on macrophage polarization, elucidate its mechanisms, and evaluate its regulatory functions in the regeneration of periodontal tissues.

MATERIALS AND METHODS

A ligature-induced periodontitis mouse model was established to investigate the correlation between macrophage polarization markers and ENTR1 expression. Techniques including qRT-PCR, Western blot, ELISA, flow cytometry, and immunofluorescence staining were utilized to evaluate the impact of ENTR1 on macrophage polarization under inflammatory stimuli. Micro-CT and histological staining were applied to assess periodontal bone resorption. The interaction between ENTR1 and AMP-activated protein kinase (AMPK) was explored through Western blot and co-immunoprecipitation, further validated by applying the AMPK inhibitor Compound C (CpC).

KEY FINDINGS

ENTR1 expression was down-regulated in the mice with periodontitis relative to healthy controls. Overexpressing ENTR1 suppressed macrophage M1 polarization and mitigated bone loss in periodontitis, while knocking down ENTR1 exacerbated these effects. ENTR1 directly interacted with AMPK, enhancing its phosphorylation. Furthermore, the inhibitory impact of ENTR1 on macrophage M1 polarization and inflammation-induced alveolar bone resorption were partially attenuated by CpC treatment.

SIGNIFICANCE

ENTR1 regulates periodontitis by suppressing macrophage M1 polarization through enhancing AMPK phosphorylation, presenting a promising therapeutic target for its prevention and management.

A nucleoside-based supramolecular hydrogel integrating localized self-delivery and immunomodulation for periodontitis treatment

Periodontitis is a highly prevalent oral disease characterized by bacterial-induced hyperactivation of the host immune system, leading to a sustained inflammatory response and osteoclastic activity, which ultimately results in periodontal destruction. In this work, an immunomodulatory supramolecular hydrogel for the topical treatment of periodontitis was synthesized using a simple one-pot method. This phenylboronate ester-based 8AGPB hydrogel exhibited excellent stability, self-healing properties, injectability, and biocompatibility. During degradation, the 8AGPB hydrogel releases immunomodulatory agent 8-aminoguanosine (8AG), which regulates MAPK and NF-κB signaling pathways by modulation of second messengers in macrophages. In combination with 1,4-phenylenediboronic acid (PBA), which possesses antioxidant properties, 8AG effectively inhibits ROS production and oxidative damage in LPS-stimulated macrophages, lowering the M1/M2 macrophage polarization ratio and reducing the secretion of pro-inflammatory factors. In an experimental periodontitis model using C57BL/6 mice, periodontal injection of the 8AGPB hydrogel reduced inflammatory infiltration and osteoclastic activity through immunomodulation and inhibition of osteoclast differentiation, thereby ameliorating periodontal destruction during periodontitis progression. Overall, the 8AGPB supramolecular hydrogel, serving as an injectable self-delivery platform for 8AG, may represent a promising novel strategy for periodontitis treatment and offer insights for the development of future topical anti-inflammatory systems.

Mucosal Wetness, Hyposalivation, and Local Defense in Periodontal Inflammation

OBJECTIVE

To evaluate the potential relationship between local salivary coating of mucosal surfaces, clinical periodontal status, hyposalivation, and local inflammatory response with a specific reference for MUC4 and TNF-α levels.

MATERIALS AND METHODS

Based on their salivary flow rates, 24 hyposalivators and 26 normosalivators were recruited. Mucosal wetness (MW) and mucosal surface pH values were determined. Clinical periodontal parameters were recorded and gingival crevicular fluid (GCF) samples were obtained. Mucin 4 (MUC4) and TNF-α levels in local and whole salivary and GCF samples were determined with ELISA kits.

RESULTS

GI and BoP were significantly higher in the hyposalivation group, while MW and mucosal pH values were significantly lower in hyposalivators, except for the labial surface. MUC4 and TNF-α levels showed significant differences among the groups. In the anterior region, GCF TNF-α concentration was high in hyposalivation patients; in the molar region, GCF MUC4 was significantly higher in normosalivators.

CONCLUSIONS

Based on the differences which MW presented at local sites, MW may be utilized as a possible practical tool to reveal the local salivary characteristics in various clinical periodontal conditions based on the presence/extent of local inflammatory response, which may be important when the site-specific nature of periodontal diseases is concerned.

Poly-T-Modified Gold Nanorods Suppress Macrophage-Mediated Inflammation for Periodontitis Therapy

Traditional treatments for periodontitis are limited by their inability to adequately modulate the immune response and control inflammation. Recently, nucleic acid-modified nanomaterials have attracted significant attention for their potential in regulating inflammation. Among these, most nanomaterials, such as spherical nucleic acids, tend to exhibit pro-inflammatory effects. In this study, we identified for the first time that poly-T sequence-modified gold nanorods (PTM AuNRs) possess significant anti-inflammatory properties. The PTM AuNRs demonstrated excellent biocompatibility and efficacy in treating ligation-induced periodontitis. PTM AuNRs modulate immune responses by inhibiting the differentiation of pro-inflammatory M1 macrophages and reducing pro-inflammatory cytokine levels through promoting AMPK activation. When administered via local injection, PTM AuNRs effectively suppress inflammatory response and inflammatory cell infiltration, downregulate inflammatory cytokine levels, and mitigate collagen fiber degradation and alveolar bone loss. Together, these findings highlight PTM AuNRs as a promising and innovative therapeutic strategy for periodontitis management.

Proanthocyanidin B2 alleviates Pg.LPS-induced RAW264.7 cellular inflammation and oxidative stress via PI3K/Akt/NFkB pathway

Periodontitis is a multifactorial chronic inflammatory infectious disease associated with systemic diseases. Proanthocyanidin B2 (PB2), a polyphenol, has been investigated to exhibit antioxidant, anti-inflammatory and anti-cancer pharmacological properties. PB2 has shown good efficacy in treating hepatocellular carcinoma, type 2 diabetes mellitus, and ulcerative colitis. There are few studies on PB2 in treating periodontitis, and the molecular mechanism is unknown. This research focused on the effects of PB2 in Porphyromonas gingivalis-derived lipopolysaccharide (Pg. LPS)-stimulated RAW264.7 cells, as well as the potential mechanisms. CCK-8 assay was used to assess the cytotoxic effects of PB2. qRT-PCR assay and ELISA assay were used to evaluate the expression of inflammatory cytokines. DCFH-DA probe and other assay kits were employed to detect oxidative stress indicators. Western blot was conducted to assess important proteins of the PI3K/Akt/NFκB pathway. The results showed that PB2 downregulated the overproduction of pro-inflammatory mediators IL-1β, IL-6, and TNF-α; reduced the generation of ROS, MDA, and NO; Enhanced the activities of anti-inflammatory factor IL-10 and the total antioxidant capacity; and inhibited the activation of PI3K/Akt/NFκB pathway. In addition, the PI3K agonist 740Y-P was able to partially reverse the effects of PB2. This study indicates that PB2 exhibits significant anti-inflammatory and antioxidant effects in P. gingivalis LPS-stimulated RAW264.7 cells, primarily through the inhibition of the PI3K/Akt/NFκB signaling pathway.

Inflammation-triggered Gli1+ stem cells engage with extracellular vesicles to prime aberrant neutrophils to exacerbate periodontal immunopathology

Periodontitis is a prevalent and progressive detrimental disease characterized by chronic inflammation, and the immunopathological mechanisms are not yet fully understood. Mesenchymal stem cells (MSCs) play crucial roles as immunoregulators and maintain tissue homeostasis and regeneration, but their in vivo function in immunopathology and periodontal tissue deterioration is still unclear. Here, we utilized multiple transgenic mouse models to specifically mark, ablate and modulate Gli1+ cells, a critical and representative subset of MSCs in the periodontium, to explore their specific role in periodontal immunopathology. We revealed that Gli1+ cells, upon challenge with an inflammatory microenvironment, significantly induce rapid trafficking and aberrant activation of neutrophils, thus exacerbating alveolar bone destruction. Mechanistically, extracellular vesicles (EVs) released by Gli1+ cells act as crucial immune regulators in periodontal tissue, mediating the recruitment and activation of neutrophils through increased neutrophil generation of reactive oxygen species and stimulation of nuclear factor kappa-B signaling. Furthermore, we discovered that CXC motif chemokine ligand 1 (CXCL1) is exposed on the surface of EVs derived from inflammation-challenged Gli1+ cells to prime aberrant neutrophils via the CXCL1-CXC motif chemokine receptor 2 (CXCR2) axis. Importantly, specific inhibition of EV release from Gli1+ cells or pharmacological therapy with GANT61 ameliorates periodontal inflammation and alveolar bone loss. Collectively, our findings identify previously unrecognized roles of Gli1+ cells in orchestrating infiltration and promoting aberrant activation of neutrophils under inflammation, which provides pathological insights and potential therapeutic targets for periodontitis.

Apabetalone alleviates ligature-induced periodontitis by inhibiting M1 macrophage polarization via an immunometabolic shift

OBJECTIVES

To explore the effects and biological mechanism of apabetalone on periodontal inflammation by regulating glycolysis and metabolites.

METHODS

A ligature-induced periodontitis model was established in mice and apabetalone was administered on the ligation silk for two weeks. Inflammation levels and alveolar bone absorption were explored using micro-computed tomography and histopathological analysis. To observe the role of apabetalone in macrophage polarization and the macrophage-mediated immune microenvironment, a Luminex assay, quantitative real-time polymerase chain reaction, a conditioned medium experiment, a Seahorse extracellular flux assay and quantitative metabolomics were used for molecular biological analysis.

RESULTS

Apabetalone-treated mice exhibited ameliorated alveolar bone loss and inflammatory infiltration in the periodontium. Furthermore, apabetalone significantly inhibited the production of proinflammatory cytokines and suppressed the levels of M1-specific biomarkers both in vivo and in vitro. Apabetalone also promoted the osteogenic potential of mouse periodontal ligament cells in a macrophage-mediated microenvironment. Apabetalone restrained LPS-induced glucose uptake and lactic acid production. Apabetalone inhibited glycolysis by suppressing the transcription and protein expression of hexokinase 2, glucose transporter 1 and phosphofructokinase-2/fructose-2,6- bisphosphatase 3 (PFKFB3) in a dose-dependent manner. Quantitative analysis of certain carbohydrates involved in energy metabolism revealed that apabetalone reserved the disruption of the tricarboxylic acid (TCA) cycle and inhibited glycolysis and the pentose phosphate pathway. In addition, apabetalone increased the oxygen consumption rate.

CONCLUSION

Collectively, these findings indicate that apabetalone improves the periodontal immune microenvironment by regulating metabolites in macrophages. Apabetalone exerts anti-inflammatory and osteo-protective effects by replenishing the broken TCA cycle and suppressing glycolysis. Apabetalone is a potential candidate for the treatment of periodontitis.

Impact of increased Porphyromonas gingivalis peptidylarginine deiminase (PPAD) T2 variant allele on oral microbiota composition and severity of chronic periodontitis

Background

Porphyromonas gingivalis (Pg) is a keystone pathogen in periodontitis, encoding a unique peptidyl arginine deiminase (PPAD) linked to protein citrullination, a process associated with rheumatoid arthritis (RA). Recently, we identified a super-active PPAD variant (T2) in Pg isolates. Here, we evaluated if the presence of the super-active T2 variant of PPAD affects the salivary microbiome, the severity of chronic periodontitis (CP), and subsequently CP's causative association with RA onset/progression.

Patients/Materials and Methods

We examined 56 CP patients and 36 healthy volunteers. Pg and Tannerella forsythia counts were measured via RT-PCR, and PPAD variant was typed via PCR. 16S rRNA from salivary DNA sequencing characterized microbiota composition, while CP severity was assessed through bleeding on probing (BoP), clinical attachment loss (CAL), and pocket depth (PD) parameters.

Results

CP patients exhibited higher Pg and T. forsythia counts, with 30.7% harbouring the PPAD-T2 variant, compared to only one healthy volunteer. Clinical CP parameters were unaffected by the PPAD variant. However, PPAD-T2 influenced oral microbiota composition, enriching certain genera.

Conclusion

While the PPAD variant did not affect CP severity, it influenced oral microbiota composition. Further research is needed to understand citrullination's role in oral microbiota and chronic inflammatory disease development.

Critical roles of extracellular vesicles in periodontal disease and regeneration

Extracellular vesicles (EVs) are evolutionarily conserved communication mediators that play key roles in the development of periodontal disease as well as in regeneration processes. This concise review first outlines the pathogenic mechanisms through which EVs derived from bacteria lead to the progression of periodontitis, with a focus on the enrichment of virulence factors, the amplification of immune responses, and the induction of bone destruction as key aspects influenced by bacterial EVs. This review aims to elucidate the positive effects of EVs derived from mesenchymal stem cells (MSC-EVs) on periodontal tissue regeneration. In particular, the anti-inflammatory properties of MSC-EVs and their impact on the intricate interplay between MSCs and various immune cells, including macrophages, dendritic cells, and T cells, are described. Moreover, recent advancements regarding the repair-promoting functions of MSC-EVs are detailed, highlighting the mechanisms underlying their ability to promote osteogenesis, cementogenesis, angiogenesis, and the homing of stem cells, thus contributing significantly to periodontal tissue regeneration. Furthermore, this review provides insights into the therapeutic efficacy of MSC-EVs in treating periodontitis within a clinical context. By summarizing the current knowledge, this review aims to provide a comprehensive understanding of how MSC-EVs can be harnessed for the treatment of periodontal diseases. Finally, a discussion is presented on the challenges that lie ahead and the potential practical implications for translating EV-based therapies into clinical practices for the treatment of periodontitis.

Oral Medicine and Oral Clinical Chemistry Game Changers for Future Plaque Control and Maintenance: PerioSafe® aMMP-8 POCT, Lumoral® 2× PDT- and Lingora® Fermented Lingonberry Oral Rinse-Treatments

Background: Periodontitis is a global health crisis that affects almost half of the world's population and commonly goes unnoticed because of its asymptomatic and pain-free nature. For early and easy detection and treatment, safe and non-invasive chair-side oral fluid biomarker (aMMP-8) diagnostics and new anti-microbial, anti-inflammatory and anti-proteolytic treatment modalities have been developed, which this review aims to introduce. Methods: For convenient diagnosis and tackling of periodontitis, adoption of an oral fluid aMMP-8 chair-side point-of-care rapid diagnostic test (POCT) has been proposed, comparable to home pregnancy and COVID-19 antigen tests, to be conveniently used by healthcare professionals and by patients themselves. To improve treatment of detected periodontitis, Finnish scientists have also developed a potentially industry-altering, biofilm-modulating, anti-microbial, anti-inflammatory, and anti-proteolytic (i) dual-light-activated photodynamic-therapy (2×PDT) and (ii) fermented lingonberry juice (FLJ) oral rinse designed for home personalized medicine and professional use. These new oral medicine technologies are reviewed and some unpublished results are presented. Results: aMMP-8 is the superior biomarker for grade of periodontitis (progression rate) when compared to the total latent/proform MMP-8 (total-MMP-8) and microbial lipopolysaccharide (LPS/LAL) activity. Cut-off 20 ng/mL is the optimal cut-off for aMMP-8 POCT and does not make false positives. Antibacterial 2× PDT light and anti-microbial FLJ treatments can eliminate and reduce problem-causing bacteria and Candida-yeasts from the mouth. Conclusions: These new oral medicine technologies have shown promising results and could have the potential to revolutionize diagnosis, prevention, oral care, plaque control and maintenance. These new game-changer oral medicine technologies have launched a new clinical field in dentistry: oral clinical chemistry.

Histological Assessment of the Anti-Inflammatory Effectiveness of Peperomia pellucida Extract Administered to the Gingival Sulcus in Rats Induced with Periodontitis

This study aims to assess the impact of Peperomia pellucida extract on periodontitis in rats, using the Papillary Bleeding Index (PBI), gingival index (GI), and histological evaluation of key inflammatory cells such as osteoclasts, osteoblasts, polymorphonuclear neutrophils (PMNs), macrophages, and fibroblasts to explore its potential in reducing inflammation and preserving periodontal tissue.The extract was prepared using the reflux method with 96% ethanol as a solvent, followed by phytochemical screening and antibacterial testing via the disk diffusion method. This in vivo study utilized a posttest control group experiment with 24 Wistar rats, divided into four groups: nonperiodontitis, no-treatment, chlorhexidine-treated (CHX), and extract-treated groups, with the latter three groups induced with periodontitis. Induction was performed using a 0.3-mm ligature wire and plaque from periodontitis patients, along with nicotine administration (0.001 mg/L) for 7 days. The extract group received a topical application of 2.5 µL of P. pellucida leaf extract, while the CHX group was administered 0.05 mL of CHX daily for 1 week. Observations of GI and PBI were made on days 0, 3, 5, and 7. Histological changes were assessed on day 7 by evaluating the cell counts of osteoclasts, osteoblasts, fibroblasts, macrophages, and PMNs.Data were analyzed using one-way analysis of variance and Kruskal-Wallis with Mann-Whitney post hoc tests for pairwise comparisons.Phytochemical analysis confirmed the presence of alkaloids, polyphenols, tannins, flavonoids, quinones, monoterpenoids, and sesquiterpenoids in P. pellucida extract. The extract demonstrated antibacterial activity against Porphyromonas gingivalis, a key pathogen in periodontitis. Clinical and histological assessments showed significant improvements in the extract-treated group, with outcomes comparable to the CHX-treated group after 7 days.Based on these findings, P. pellucida (L.) Kunth extract contains phytochemicals and exhibits antibacterial and anti-inflammatory properties, as demonstrated by clinical and histological parameters in rats induced with periodontitis.

Investigation of the relationship between apical periodontitis and host modulation provided by nutritional supplement: a study in rats

BACKGROUND

Traditional treatments often involve chemotherapeutic agents; however, immune modulation agents, such as probiotics, propolis, Vitamin E, and vegetable oils, may offer alternative approaches to reduce inflammation and bone damage. In this study, we aimed to investigate the effect of various host modulation agents (probiotics, propolis, Vitamin E, and vegetable oils) on inflammation and bone loss in a rat model of experimental apical periodontitis (AP).

METHODS

Eight-week-old Sprague-Dawley rats (n = 79) were used. AP was induced by exposing the coronal pulp of the mandibular right first molar. Rats were divided into seven groups: Control, AP, AP + Vegetable Oil, AP + Probiotic, AP + Propolis, AP + Vitamin E, and AP + Physiological Serum. The host modulation agents were administered daily for 30 days. Serum calcium, phosphorus, and alkaline phosphatase levels were measured, along with histopathological and immunohistochemical evaluations. Statistical analyses were conducted using one-way ANOVA and Tukey's test (p < 0.05).

RESULTS

Vitamin E and vegetable oil significantly reduced inflammation by 33% and 28%, respectively, compared with the AP group (p < 0.0001 for both). Probiotics reduced fibrosis by 36% (p = 0.0002), and all agents except propolis showed lower serum calcium levels (p = 0.0017) than the AP group. Osteoblastic activity was higher in the AP and Vitamin E groups (p = 0.0366), whereas both propolis and vitamin E treatments resulted in a 20% reduction in osteoclastic activity (p = 0.0389). No significant effect on abscess formation was observed (p = 0.2610). Compared to the AP group, RANKL levels were significantly lower in the supplemented groups by 28-50% (p = 0.0036).

CONCLUSIONS

Specific nutritional supplements with host modulation effectively reduced inflammation and bone loss in experimental AP. These findings suggest the potential of these agents in improving endodontic treatment outcomes. Further studies are required to explore their clinical application.

Creatine promotes osteogenic differentiation of dental pulp stem cells via the AMPK-ULK1-autophagy axis

OBJECTIVE

We aimed to demonstrate the effects of creatine (Cr) on osteogenic differentiation (OD) in HDPSCs.

MATERIALS AND METHODS

HDPSCs were treated with Cr and an inhibitor of Cr transporter. The OD capacity was evaluated by detecting ALP staining and activity, alizarin red staining (ARS), as well as osteogenesis-related protein levels. Transcriptomic sequencing, western blotting, transmission electron microscopy, immunofluorescence staining, and autophagy-related protein marker detection were applied to illustrate the underlying mechanism. Furthermore, the impact of Cr on bone regeneration was investigated in vivo.

RESULTS

We found that 1 mm of Cr effectively enhanced the OD of HDPSCs. The creatine group displayed significantly increased AMPK phosphorylation, overexpressed autophagy-related proteins, enhanced OD, and mineralization capabilities. We also found that ULK1 is the downstream molecule through which AMPK induces cellular autophagy. In vivo results demonstrated that Cr could increase the new bone formation of periodontitis.

CONCLUSION

Our research discovered a new AMPK-ULK1-autophagy pathway through which Cr enhances OD in HDPSCs. Cr enhanced HDPSCs-mediated periodontal tissue regeneration in a periodontitis mouse model, providing a theoretical foundation for the study of bone repair in periodontitis.

Finite element stress analysis to evaluate and compare the effect of splinting in periodontally compromised teeth having 55 % bone loss with different materials

Background

Splinting is commonly employed to stabilize periodontally compromised teeth, but the choice of splint material significantly influences stress distribution within the periodontal ligament (PDL) and surrounding bone. This study aimed to evaluate and compare the stress distribution of four different splint materials-composite, fiber-reinforced composite (FRC), polyetheretherketone (PEEK), and metal-on mandibular anterior teeth with 55 % bone loss using finite element analysis (FEA).

Methodology

Finite element models of mandibular anterior teeth with 55 % bone loss were developed using SOLIDWORKS 2020. Simulations were conducted for non-splinted teeth and for teeth splinted with composite, FRC, PEEK, and metal. Stress analysis was performed in ANSYS software under vertical (100N at 0°) and oblique (100N at 45°) loading conditions. Von Mises stress values in the PDL and cortical bone were recorded and statistically analyzed using MedCalc software to compare the performance of different splint materials.

Results

Non-splinted teeth exhibited the highest stress levels, particularly under oblique loading conditions. Among the splinting materials, FRC showed the most effective reduction in stress across all teeth, especially under vertical loads. Composite and metal wire splints provided moderate stress reduction, with performance varying depending on the load angle. PEEK splints demonstrated good stress reduction under vertical loads but showed increased stress levels under oblique forces. These results underscore the influence of splint material and load direction on stress distribution in periodontally compromised teeth.

Conclusion

The study highlights the critical role of splint material in reducing stress on the PDL of periodontally compromised teeth. FRC splints emerged as the most effective material for minimizing stress under both vertical and oblique loading conditions. Composite and metal wire splints offered moderate efficacy, while PEEK splints were less effective under oblique loads. These findings provide valuable insights for clinicians in selecting optimal splint materials for periodontal stabilization.

A systematic review of the implications of lipocalin-2 expression in periodontal disease

OBJECTIVE

Evidence suggests that lipocalin-2 (LCN-2), a bone-derived protein, is upregulated in periodontal diseases. This systematic review aimed to evaluate LCN-2 concentrations in individuals with periodontal diseases, identifying the most suitable body fluids for its detection, the type of periodontal disease with the highest LCN-2 expression, its association with other inflammatory markers and systemic diseases, and whether its expression can be modified by periodontal treatment.

METHODS

A systematic search of Google Scholar, PubMed, and ProQuest up to August 2024 was conducted. The studies were screened and selected by the authors according to specific eligibility criteria. Quality assessment of the included studies was performed according to the study type using STROBE statement for observational studies or the modified Jadad scale for experimental studies. The review was registered in PROSPERO (CRD42023458565).

RESULTS

In total, three thousand six hundred and thirty-eight reports were identified, of which twenty-seven were full-text assessed for eligibility, including eleven articles. Seven articles were observational, and four were experimental. Significantly elevated LCN-2 levels were reported in patients with periodontal disease across 9 studies, being higher in periodontitis rather than gingivitis. LCN-2 was mainly detected in gingival crevicular fluid (GCF) and saliva. LCN-2 expression is related to the increment of inflammatory markers, and periodontal therapy decreases LCN-2 concentrations. LCN-2 levels were aggravated when periodontitis was accompanied by obesity and type 2 diabetes.

CONCLUSION

LCN-2 is implicated in periodontal diseases, probably through the inflammation process.

Multifunctional Injectable Bioadhesive with Toll-like Receptor 4 and Myeloid Differentiation Factor 2 Antagonistic Anti-inflammatory Potential for Periodontal Regeneration

Effectively addressing inflammation in periodontitis is challenging as conventional injectable hydrogels typically require the addition of drugs to provide sufficient anti-inflammatory effects. To overcome this limitation, we developed a multifunctional injectable hydrogel with inherent properties that antagonize the Toll-like receptor 4 and myeloid differentiation factor 2 complex (TLR4-MD2). This hydrogel allows for direct inhibition of inflammatory pathways without the need for additional drugs. We identified xylitol, caffeic acid, and citric acid as natural materials that effectively meet biological needs for anti-inflammatory and antibacterial effects as well as support bone regeneration. With this in mind, we developed a caffeic-acid-modified poly(xylitol succinate) (PXS)-based iCPC@MgO composite hydrogel and tested its potential application for periodontal regeneration. The iCPC@MgO hydrogel demonstrated rapid wet tissue adhesion and injectability, which are ascribed to incorporating catechol groups derived from caffeic acid. Intriguingly, the PXS polymer used for synthesizing the hydrogel was found to possess anti-inflammatory properties and act as an antagonist for the TLR4-MD2 complex. This hydrogel also exhibited outstanding antibacterial efficiency against Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans by stimulating antibiotic synthesis within bacteria and disrupting bacterial cell walls. In a periodontitis mouse model, the iCPC@MgO hydrogel demonstrated the therapeutic potential of reducing inflammatory factors, inhibiting dominant periodontitis-associated bacteria, and maintaining subgingival microbiota balance in addition to the regenerative effects. These properties, combined with their ecofriendly nature, firmly established the iCPC@MgO hydrogel as a highly promising option for use in periodontitis therapy as well as in tissue healing, repair, and regeneration in various other inflammatory conditions.

In vitro modulation of proinflammatory and proteolytic activities of Porphyromonas gingivalis by selected lactobacilli

Objective

The aim of the present study was to characterize the antimicrobial and anti-inflammatory activities of postbiotics from lactic acid bacteria against Porphyromonas gingivalis.

Material and methods

The anti-P. gingivalis activity of postbiotics from the CERELA culture collection was assessed by measuring changes in the expression of key host proteins by ELISA and qPCR, the proteolytic activity by a fluorescence and a spectrophotometric method and virulence factors from P. gingivalis by qPCR.

Results

Even though Lacticaseibacillus (L.) rhamnosus CRL1522 and Lactiplantibacillus (L.) plantarum CRL1363 exhibit only a discrete antibacterial activity against P. gingivalis, the cell-free supernatants of these strains significantly reduced P. gingivalis-induced secretion of interleukins IL-6 and IL-8 by keratinocytes and TNF-α and IL-6 by U937 macrophage-like cells. More importantly, P. gingivalis arginine-gingipain (Rgp) protease activity was markedly reduced by both lactic acid bacteria (LAB) strains. This finding is particularly interesting because it means that both LAB might prevent the ulterior citrullination of peptides and the consequent generation of autoantibodies. The expression of COX2 and TLR2 was also significantly downregulated in macrophages.

Conclusion

Postbiotics from L. rhamnosus CRL1522 and L. plantarum CRL1363 rise as suitable candidates for antagonizing the periodontopathogen P. gingivalis, since they were able to reduce the expression of proinflammatory cytokines and the protein degradation induced by this pathogen. We propose that postbiotics from these LAB could potentially halt the progression of periodontitis based on this in vitro study.

pH-Responsive Polyglycerol Nanogels for Periodontitis Treatment through Antibacterial and Pro-Angiogenesis Action

Periodontitis is a microbe-driven inflammatory disease leading to bone resorption and tissue destruction. We propose a dual-functional nanogel complex armed with the antimicrobial drug triclosan (TCS) and the pro-angiogenesis medication deferoxamine (DFO) for combating microbial pathogens and promoting tissue regeneration. The nanogel system (NG-TCS-DFO) that we fabricated from linear polyglycerol exhibits well-defined spherical morphology and a positively charged surface for bacteria adhesion. The rapid and sustained degradation of NG-TCS-DFO in the acidic environment of an infection site induces the on-demand release of TCS and DFO. The NG-TCS-DFO shows potent bacteria elimination of the gingivitis-causing bacteria Porphyromonas gingivalis in both planktonic (99.9 %) and biofilm (99 %) states. Furthermore, the NG-TCS-DFO can promote vascularization and migration of human umbilical vein endothelial cells (HUVECs). Contributing to the synergistic effect of TCS and DFO, the NG-TCS-DFO demonstrates significant bone tissue regeneration and accelerated healing of periodontitis in vivo. This polyglycerol-based nanogel may therefore offer smart combined delivery of multiple therapeutics against bacteria-driven diseases.

Innate immune training of osteoclastogenesis promotes inflammatory bone loss in mice

We previously demonstrated that long-term trained immunity (TRIM) involves adaptations that imprint innate immune memory in long-lived myelopoiesis precursors and their progeny, monocytes/macrophages and neutrophils, which thereby acquire enhanced responsiveness to future challenges. Here, we show that a distinct component of myeloid biology, osteoclastogenesis, can also undergo innate immune training. Indeed, β-glucan-induced TRIM was associated with an increased osteoclastogenesis bias in the bone marrow and an expansion of monocytes/osteoclast progenitors in the periphery, resulting in aggravated severity of experimental periodontitis and arthritis. In the setting of trained inflammatory osteoclastogenesis, we observed transcriptomic rewiring in synovial myeloid cells of arthritic mice, featuring prominent upregulation of the transcription factor melanogenesis-associated transcription factor (MITF). Adoptive transfer of splenic monocytes from β-glucan-trained mice to naive recipients exacerbated arthritis in the latter in a strictly MITF-dependent manner. Our findings establish trained osteoclastogenesis as a maladaptive component of TRIM and potentially provide therapeutic targets in inflammatory bone loss disorders.

Xianling Gubao capsules improve oral health, alveolar bone defects, and bone density in patients with periodontitis

OBJECTIVE

To evaluate the effects of Xianling Gubao Capsules (XGC) on alveolar bone and inflammatory mediators in the gingival crevicular fluid in patients with periodontitis.

METHODS

A retrospective analysis was conducted on 90 periodontitis patients who received medication treatment at Daqing Longnan Hospital from September 2022 to June 2023. Patients were categorized into three groups: a control group (n=30, receiving basic periodontal treatment), a Caltrate group (n=30, receiving basic treatment plus Caltrate), and an XGC group (n=30, receiving basic treatment plus Xianling Gubao Capsules). Changes in alveolar bone defect height, alveolar bone density, plaque index (PI), probing depth (PD), gingival index (GI), gingival crevicular fluid volume, and inflammatory mediator levels were compared before and after treatment.

RESULTS

After 3 and 6 months of treatment, the XGC group exhibited significantly reduced alveolar bone defect height in incisors, canines, premolars, and molars and significantly increased alveolar bone density compared with the other two groups (all P<0.05). The XGC group also exhibited lower tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels and higher interleukin-17 (IL-17) levels than the Caltrate and control groups (all P<0.05). Additionally, PI, PD, GI, and gingival crevicular fluid volume were significantly lower in the XGC group at both time points (all P<0.05). The incidence of adverse reactions did not differ significantly among the three groups (P>0.05).

CONCLUSION

Xianling Gubao Capsules, when combined with conventional periodontal treatment, may enhance alveolar bone density, reduce alveolar bone defects, alleviate periodontal inflammation, and modulate inflammatory mediator levels in the gingival crevicular fluid. These findings suggest clinical benefits for periodontitis management.

SIRT3 alleviates mitochondrial dysfunction and senescence in diabetes-associated periodontitis by deacetylating LRPPRC

Diabetes-associated periodontitis (DP) is recognized as an inflammatory disease that can lead to teeth loss. Uncontrolled chronic low-grade inflammation-induced senescence impairs the stemness of human periodontal stem cells (hPDLSCs). Sirtuin 3 (SIRT3), an NAD+-dependent deacetylase, is pivotal in various biological processes and is closely linked to aging and aging-related diseases. This study aims to explore the mechanism of SIRT3-related senescence and osteogenic differentiation of hPDLSCs under DP and explored the novelty therapeutic targets. Our study revealed that SIRT3 expression was markedly inhibited in periodontal ligament stem cells (PDLSCs) stimulated by high glucose and lipopolysaccharide. Both in vitro and in vivo, reduced SIRT3 expression accelerated cell senescence and impaired osteogenic differentiation of hPDLSCs. We demonstrated that SIRT3 binds to and deacetylates leucine-rich pentatricopeptide repeat-containing protein (LRPPRC), thereby modulating senescence. Additionally, we found that LRPPRC regulates senescence by modulating oxidative phosphorylation and oxidative stress. The activation of SIRT3 by honokiol significantly delayed senescence and promoted alveolar bone regeneration in mice after DP. Our findings indicate that the activation of SIRT3 negatively regulates hPDLSCs senescence by deacetylating LRPPRC, suggesting SIRT3 as a promising therapeutic target for DP.

IgG In Saliva, GCF, and Serum in Young Patients With Grade C Molar Incisor Pattern Periodontitis

OBJECTIVE

This cross-sectional study aimed to investigate immunoglobulin G levels in saliva, gingival crevicular fluid, and serum samples from young patients with grade C molar incisor pattern periodontitis (C/MIP) and age-matched periodontitis-free controls.

METHODS

Saliva, gingival crevicular fluid, and blood samples were collected from 62 patients, divided into 31 cases and 31 periodontitis-free age-matched controls. Saliva and blood samples were centrifuged to extract supernatant and serum. Gingival crevicular fluid periopapers were eluted. Human total immunoglobulin G levels were assessed using an Enzyme-Linked Immunosorbent Assay.

RESULTS

After adjusting for covariates, cases had higher Immunoglobulin G levels in saliva (p = 0.005), gingival crevicular fluid (p < 0.001) than controls; however, serum did not reach the significant threshold (p = 0.137). Among other factors contributing to immunoglobulin G levels, males had higher serum immunoglobulin G than females (p = 0.018), and serum immunoglobulin G levels increased with age (p = 0.033). Gender and ethnicity subgroup analyses revealed that C/MIP males had higher saliva IgG (p = 0.018) than control males, and both genders had higher GCF IgG than controls (p ≤ 0.001). C/MIP Caucasians had elevated saliva (p = 0.011) and GCF IgG p = (0.003) compared to the controls, and Asians had higher GCF IgG than the controls (p = 0.011).

CONCLUSION

This study shows for the first time that C/MIP cases have higher Immunoglobulin G levels than controls in saliva and gingival crevicular fluid, confirming its association with C/MIP pathogenesis and suggesting that it could be a potential biomarker in grade C molar incisor pattern periodontitis. Further research on a larger sample size is needed.

Emerging therapeutic strategies targeting bone signaling pathways in periodontitis

Periodontitis is a multifactorial immune-mediated disease exacerbated by dysregulated alveolar bone homeostasis. Timely intervention is crucial for disease management to prevent tooth loss. To successfully manage periodontitis, it is imperative to understand the cellular and molecular mechanisms involved in its pathogenesis to develop novel treatment modalities. Non-surgical periodontal therapy (NSPT) such as subgingival instrumentation/debridement has been the underlying treatment strategy over the past decades. However, new NSPT approaches that target key signaling pathways regulating alveolar bone homeostasis have shown positive clinical outcomes. This narrative review aims to discuss endogenous bone homeostasis mechanisms impaired in periodontitis and highlight the clinical outcomes of preventive periodontal therapy to avoid invasive periodontal therapies. Although the anti-resorptive therapeutic adjuncts have demonstrated beneficial outcomes, adverse events have been reported. Diverse immunomodulatory therapies targeting the osteoblast/osteoclast (OB/OC) axis have shown promising outcomes in vivo. Future controlled randomized clinical trials (RCT) would help clinicians and patients in the selection of novel preventing therapies targeting key molecules to effectively treat or prevent periodontitis.

A Study Into Systemic and Oral Levels of Proinflammatory Biomarkers Associated With Endpoints After Active Non-Surgical Periodontal Therapy

AIM

To analyse whether some selected inflammatory biomarkers collected from venous blood and gingival crevicular fluid (GCF) were associated with the outcome of non-surgical periodontal therapy.

MATERIALS AND METHODS

Two-hundred and nine patients affected by periodontitis were enrolled in the study, who had undergone steps I and II therapy as well as a non-surgical re-instrumentation (NSRI) of periodontal pockets after 6 months. Serum (SE), plasma (PL) and GCF samples were quantitatively analysed for the following inflammatory biomarkers: active matrix metalloproteinase-8 (aMMP-8), prostaglandin E2 (PGE2) and surfactant protein D (SP-D). Therapy outcomes were evaluated using a 'treat-to-target' endpoint (T2T) at the patient level, defined as ≤ 4 sites with pocket depth ≥ 5 mm.

RESULTS

Patients presented with 23 ± 6 teeth (mean ± SD) at baseline. After steps I and II therapy, 41.6% of the patients reached T2T and after NSRI 47.4%. Univariate analysis identified a potential association between high levels of PL-SP-D and more favourable treatment outcomes. Multivariate binary logistic regression adjusted for sex, mean baseline probing depth, diabetes and current smoking status confirmed an independent relationship between baseline PL-SP-D and the T2T after steps I and II therapy (aOR 0.432, p = 0.011), implying that a higher level PL-SP-D at baseline is associated with a > 50% reduced risk of failing T2T. However, no such association was found for PL-SP-D and NSRI.

CONCLUSION

Higher baseline PL-SP-D levels might be associated with more favourable treatment outcomes after steps I and II therapy. This may be due to its role in the regulation of neutrophil function. However, further investigation is required to confirm this hypothesis. If proven, PL-SP-D could play a role as a biomarker for identifying individuals who respond differentially to primary therapy.

Influence of Hypoxic Condition on Cytotoxicity, Cellular Migration, and Osteogenic Differentiation Potential of Aged Periodontal Ligament Cells

OBJECTIVE

 This study aimed to investigate and compare the influence of hypoxic conditions on cytotoxicity, cellular migration, and osteogenic differentiation of aged periodontal ligament (PDL) cells.

MATERIALS AND METHODS

 Isolated human PDL cells from aged and young subjects were cultured under hypoxic conditions, which were treated with hydrogen peroxide (H2O2) (0, 25, 50, 100, 200, and 500 µM). To assess cytotoxicity, lactate dehydrogenase release was determined by the optical density at 490 nm, and the percentage of cell death was calculated. An in vitro wound healing assay was performed over 24 to 48 hours for cellular migration determination. Osteogenic differentiation was determined by alizarin red staining and osteogenic gene expression, including the expression of runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), and osteopontin (OPN).

RESULTS

 There was a significant difference in the percentage of cell death with high hypoxic condition (200 and 500 µM) compared to low hypoxic conditions on both day 1 and 2. The highest cellular migration was depicted at 50 µM in both young and aged groups of the in vitro wound healing assay. Osteogenic gene expression of RUNX2 in the aged group was increased at 25 and 50 µM hypoxic condition at day 7, but the expression was gradually decreased after 14 days. On the contrary, the expression of ALP and OPN in the aged group was increased at day 14. Only OPN had been found to be statistically significantly different when compared with gene expression at day 7 and 14 (p < 0.05). The results showed no statistically significant differences when compared with the young and aged groups in all genes and all concentrations.

CONCLUSION

 The concentration of low hypoxic condition (25-50 µM) was proposed to promote cell viability, cellular migration, and osteogenic differentiation in aged PDL cells. We suggested that the potential of aged PDL cells for use in cell therapy for periodontal regeneration might possibly be similar to that of young PDL cells.

Triple-Combination Therapy with a Multifunctional Yolk-Shell Nanozyme Au@CeO2 Loaded with Dimethyl Fumarate for Periodontitis

Periodontitis, a chronic inflammatory disease, is the leading cause of tooth loss in adults and is one of the most prevalent and complex oral conditions. Oxidative stress induced by the excessive generation of reactive oxygen species (ROS) leads to periodontitis, which is closely associated with pathological processes, including mitochondrial dysfunction of periodontal cells and local immune dysregulation. However, current treatment modalities that target single pathological processes have limited long-term therapeutic effects. Herein, a multifunctional Yolk-Shell nanozyme, Au@CeO2-dimethyl fumarate (DMF), which comprehensively addresses the oxidative stress-induced pathophysiological processes of periodontitis through antioxidant activity, mitochondrial maintenance, and immune modulation mechanisms, is described. For material design logic, functionally complementary Au and CeO2 formed an excellent photothermally regulated high-efficiency nanozyme, which also provided an ideal drug carrier for DMF. As for the therapeutic logic, Au@CeO2-DMF restores mitochondrial dysfunction and immune dysregulation, which also contributes to endogenous ROS elimination, thereby achieving long-term stable therapeutic effects. In a rat model, local Au@CeO2-DMF photothermal therapy effectively alleviated ROS-induced tissue damage and restored periodontal homeostasis. Altogether, this study presents a novel antioxidant nanozyme for managing alveolar bone loss under prolonged oxidative stress and demonstrates the importance of comprehensive intervention in key pathological processes in periodontitis treatment design.

In Vitro Infection of Human Macrophages with Porphyromonas gingivalis W83

This study aimed to investigate the innate immune response of human macrophages to Porphyromonas gingivalis W83 using a novel in vitro infection model. The growth kinetics of P. gingivalis W83 were analyzed, revealing an exponential growth phase at 8 h (optical density = 0.70). To establish a reliable macrophage model, the differentiation of THP-1 monocytes into macrophages was optimized using low concentrations of phorbol 12-myristate 13-acetate (PMA). This approach induced enhanced adherence and morphological changes, with full differentiation achieved after 48 h of PMA treatment followed by 24 h of rest. Polarization towards the pro-inflammatory M1 phenotype was successfully induced with interferon-γ (IFN-γ) and lipopolysaccharide (LPS), as confirmed using cytokine profiling. Cytokine analysis using Luminex® technology demonstrated significant increases in interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), and IL-6, indicating the effective activation of macrophages towards a pro-inflammatory phenotype. Building upon this macrophage model, this study investigated the interactions between macrophages and P. gingivalis W83 during its exponential growth phase. After a one-hour infection period, bacterial DNA quantification in supernatants and lysed macrophages revealed minimal levels of internalized or adherent bacteria, supporting the hypothesis that P. gingivalis effectively evades immune detection. These findings emphasize the utility of this model in uncovering the sophisticated immune evasion strategies employed by P. gingivalis, with significant implications for the development of targeted therapeutic interventions.

Salivary proteomic analysis in patients with type 2 diabetes mellitus and periodontitis

OBJECTIVE

This study aimed to compare the salivary protein profile in individuals with Type 2 Diabetes Mellitus (DM2) and periodontitis and their respective controls.

METHODS

Eighty participants were included in the study. The four groups were formed by individuals with DM2 and periodontitis (DM2 + P, n = 20), DM2 without periodontitis (DM2, n = 20), periodontitis without DM2 (P, n = 20) and individuals without periodontitis and without DM2 (H, n = 20). Periodontal clinical examinations were performed and unstimulated saliva was collected. Proteomic analysis was performed by shotgun mass spectrometry. The results were obtained by searching the Homo sapiens database of the UniProt catalog.

RESULTS

A total of 220 proteins were identified in saliva samples. In the comparison between DM2 + P and DM2 groups, 27 proteins were up-regulated [e.g. S100-A8 was 6 times up-regulated (humoral immune response pathway)]. The DM2 + P and P groups had 26 up-regulated proteins [e.g. Immunoglobulin lambda constant 7 more than 2 times up-regulated (complement activation pathway)]. The non-DM2 groups (P and H) presented 22 up-regulated proteins [e.g. Glyceraldehyde-3-phosphate dehydrogenase more than 2 times up-regulated (Peptidyl-cysteine S-nitrosylation pathway)]. The groups without periodontitis (DM2 and H) showed 23 were up-regulated proteins [e.g. Hemoglobin subunit alpha that was more than 10 times up-regulated (cellular oxidant detoxification pathway)].

CONCLUSION

The presence of DM2 and periodontitis significantly impacts the salivary proteome. Our proteomic analysis demonstrated that changes in the S100 family proteins (S100A8 and S100 A9) are highly related to the presence of DM2 and periodontitis.

CLINICAL RELEVANCE

Diabetes Mellitus (DM) and periodontitis are highly prevalent chronic diseases that present a wide variety of signs and symptoms. They present a bidirectional relationship, where patients with DM have a higher prevalence and severity of periodontitis, and patients with periodontitis have a higher prevalence of DM, worse glycemic control, and more diabetic complications. Diagnosing periodontitis requires specific clinical examinations, which require a highly trained operator. In this study, we used high throughput proteomics in order to evaluate non-invasive biomarkers for periodontitis in type 2 DM subjects. The results can contribute to earlier, more accurate, and less costly diagnosis of periodontitis in diabetic subjects, enabling better diabetes control.

The impact of aging on neutrophil functions and the contribution to periodontitis

The increasing aging population and aging-associated diseases have become a global issue for decades. People over 65 show an increased prevalence and greater severity of periodontitis, which poses threats to overall health. Studies have demonstrated a significant association between aging and the dysfunction of neutrophils, critical cells in the early stages of periodontitis, and their crosstalk with macrophages and T and B lymphocytes to establish the periodontal lesion. Neutrophils differentiate and mature in the bone marrow before entering the circulation; during an infection, they are recruited to infected tissues guided by the signal from chemokines and cytokines to eliminate invading pathogens. Neutrophils are crucial in maintaining a balanced response between host and microbes to prevent periodontal diseases in periodontal tissues. The impacts of aging on neutrophils' chemotaxis, anti-microbial function, cell activation, and lifespan result in impaired neutrophil functions and excessive neutrophil activation, which could influence periodontitis course. We summarize the roles of neutrophils in periodontal diseases and the aging-related impacts on neutrophil functional responses. We also explore the underlying mechanisms that can contribute to periodontitis manifestation in aging. This review could help us better understand the pathogenesis of periodontitis, which could offer novel therapeutic targets for periodontitis.

Melatonin: The potential avenues in dentistry

Melatonin, the "sleep hormone," shows significant promise in dentistry owing to its antioxidant, anti-inflammatory, and immunomodulatory properties. It is beneficial for treating periodontal disorders and aiding osseointegration of dental implants. Additionally, melatonin helps to manage dental anxiety, offering an alternative to traditional sedatives. Periodontal disease is orchestrated by bacterial plaques along with an exaggerated immune-inflammatory host response. Treatment of periodontitis not only involves the removal of plaque, but also aims to minimize the cytokine load and control the reactive oxygen species burden in the tissues, which would re-establish a healthy periodontium and a balanced bone metabolism. Melatonin is known to exert beneficial effects, such as regulation of circadian rhythm, bone remodeling, and antimicrobial effects. Recent studies have demonstrated the successful use of melatonin as an adjunct to mechanical debridement for the treatment of periodontal disease. Its various uses include systemic administration of melatonin after one-stage full-mouth Non-Surgical Periodontal Therapy in healthy subjects as well as patients. This article provides a summary of the various clinical applications of melatonin, describing its mechanism of action, uses, and potential avenues for future research in dentistry.

Nanosystems for modulation of immune responses in periodontal therapy: a mini-review

Periodontitis is one of the most common oral diseases. It is generally treated by non-surgical and/or surgical therapy with adjunctive approaches for prevention and control. The current understanding of the pathogenesis of periodontitis has unraveled the importance of the inflammatory and immune reactions to combat periodontitis whose etiology is an overlap of microbial, genetic, and environmental factors in a susceptible host. Based on this premise, many therapeutic modalities have been investigated or attempted to resolve this inflammatory disease. Amongst these, nanomedicine has been shown to have therapeutic applications in periodontitis, especially focused on immunomodulation because periodontitis is characterized by over-reactive immune response. This mini-review explores the potential of nanosystems in treating periodontitis by providing an overview of the research efforts in this field of therapeutics. The unique physicochemical and targeting properties of nanosystems seem to be potentially effective platforms for treating periodontitis.

Oral Health Related Factors Predicting Severe COVID-19 Disease in Elderly Swedes

OBJECTIVES

To analyse different background factors that may serve as predictors for acquiring symptoms of severe COVID-19 disease.

METHODS

A postal questionnaire was sent to the total population of individuals born between 1942 (80 years, n = 6299) and 1932 (90 years, n = 1904) living in the Örebro and Östergötland counties, Sweden, in 2017 and repeated in 2022. Tentative predictive factors for self-reported severe COVID-19 disease were based on the responses from the 2017 questionnaire related to general and oral health and prior to the outbreak of the COVID-19 pandemic.

RESULTS

Response rate to the main questionnaire in 2022 was 66% (5375/8203), and 577 reported having been sick with COVID-19 out of which 359 agreed to answer a separate questionnaire on COVID-19. This questionnaire was returned by 278/359 of the participants corresponding to a response rate of 77%. Information gleaned from the 2017 pre-COVID-19 survey revealed a relatively large number of associations between severity of subsequently self-reported COVID-19 disease and several diverse tentative related factors found in unadjusted regression analyses. Based on statistically significant correlations in the adjusted regression analysis, significant predictive factors (based on self-reports from 2017) for contracting severe COVID-19 were in decreasing order of odds ratios (OR): reported removable partial or complete denture usage (OR 6.2, CI 2.2-17.2); reported periodontal problems in the past year (OR 3.4, CI 1.1-10.4); and reported daytime dry mouth (OR 2.5, CI 1.2-5.2).

CONCLUSION

Removable dentures, periodontal problems and daytime dry mouth were predictors for developing symptoms of severe COVID-19 disease.

Advancing oral immunology for improving oral health

Although substantial progress has been made in dentistry in terms of diagnosis and therapy, current treatment methods in periodontology, orthodontics, endodontics, and oral and maxillofacial surgery, nevertheless, suffer from numerous limitations, some of which are associated with a dramatic reduction in the quality of life. Many general mechanisms of inflammation and immunity also apply to the oral cavity and oral diseases. Nonetheless, there are special features here that are attributable, on the one hand, to developmental biology and, on the other hand, to the specific anatomical situation, which is characterized by a close spatial relationship of soft and hard tissues, exposure to oral microbiota, and to a rapid changing external environment. Currently, a comprehensive and overarching understanding is lacking about how the immune system functions in oral tissues (oral immunology) and how oral immune responses contribute to oral health and disease. Since advances in translational immunology have created a game-changing shift in therapy in rheumatology, allergic diseases, inflammatory bowel disease, and oncology in recent years, it is reasonable to assume that a better understanding of oral immunology might lead to practice-changing diagnostic procedures and therapies in dentistry and thereby also profoundly improve oral health in general.

The effect of antireaction medications on the association between periodontitis and leprosy reactions: An important methodological issue in periodontal medicine

BACKGROUND

The treatment of leprosy reactions (LRs) involves thalidomide, corticosteroids, and other immunomodulatory medications. This study evaluated the effect of these treatments on the association between periodontitis and LRs, as well as factors associated with LRs.

METHODS

This case-control study was conducted on 283 individuals followed at a leprosy outpatient clinic in Brazil. The case group was comprised of 158 individuals presenting type 1 or type 2 LRs, and the control group of 125 leprosy individuals without reactions. A complete oral examination was performed to diagnose periodontitis, the independent variable. Antireaction medication used was collected from medical records, and participants were classified according to the use of prednisone and/or thalidomide, time of use, or non-use of medication. Socioeconomic-demographic, clinical, and lifestyle covariables were collected by interview. Unconditional logistic regression analysis by subgroups evaluated the effect of antireaction medication on the association between periodontitis and LRs, estimating the odds ratio with a 95% confidence interval (OR; 95% CI).

RESULTS

A relationship between periodontitis and LRs was observed only in the subgroup using the association prednisone and thalidomide: ORadjusted = 0.32; 95% CI = 0.11-0.95. Conversely, more severe periodontal clinical parameters were observed in cases versus controls. Several socioeconomic, health conditions, and lifestyle factors were associated with the presence of LRs.

CONCLUSIONS

Although periodontal disease indicators were worse among the cases, the findings showed a negative relationship between periodontitis and LRs in individuals receiving associated prednisone and thalidomide. These medications appear to influence the inflammatory cascade between diseases, modifying and masking the manifestations of periodontitis.

Inflammation and mechanical force-induced bone remodeling

Periodontitis arises from imbalanced host-microbe interactions, leading to dysbiosis and destructive inflammation. The host's innate and adaptive immune responses produce pro-inflammatory mediators that stimulate destructive events, which cause loss of alveolar bone and connective tissue attachment. There is no consensus on the factors that lead to a conversion from gingivitis to periodontitis, but one possibility is the proximity of the inflammation to the bone, which promotes bone resorption and inhibits subsequent bone formation during coupled bone formation. Conversely, orthodontic tooth movement is triggered by the mechanical force applied to the tooth, resulting in bone resorption on the compression side and new bone formation on the tension side. However, the environment around orthodontic brackets readily retains dental plaque and may contribute to inflammation and bone remodeling. The immune, epithelial, stromal, endothelial and bone cells of the host play an important role in setting the stage for bone remodeling that occurs in both periodontitis and orthodontic tooth movement. Recent advancements in single-cell RNA sequencing have provided new insights into the roles and interactions of different cell types in response to challenges. In this review, we meticulously examine the functions of key cell types such as keratinocytes, leukocytes, stromal cells, osteocytes, osteoblasts, and osteoclasts involved in inflammation- and mechanical force-driven bone remodeling. Moreover, we explore the combined effects of these two conditions: mechanical force-induced bone remodeling combined with periodontal disease (chronic inflammation) and periodontally accelerated osteogenic orthodontics (acute transient inflammation). This comprehensive review enhances our understanding of inflammation- and mechanical force-induced bone remodeling.

The prohibitin ligand IN44 decreases Porphyromonas gingivalis mediated inflammation

BACKGROUND

Periodontitis is an inflammatory disease causing destruction of periodontal tissues. Controlling inflammation is crucial for periodontitis treatment. Prohibitins (PHBs) are emerging targets in the treatment of inflammatory diseases. To identify compounds that would alleviate periodontitis, several small molecules that directly target PHBs and display various pharmacological activities were screened to decrease Porphyromonas gingivalis induced inflammation. Indeed, IN44, a new PHB ligand that has been shown to inhibit STAT3 and NF-kB signaling, suggesting that it may alleviate periodontitis. This study aimed to assess IN44's impact on inflammation elicited by P. gingivalis.

METHODS

In vitro, IN44 cytotoxicity was tested on periodontal cells with AlamarBlue and Live/Dead assays. Its effect on cytokines and mitochondrial ROS production were evaluated using ELISA and Mitosox assay. In mouse, systemic inflammation and experimental periodontitis were induced to assess IN44's therapeutic effects.

RESULTS

In vitro, IN44 (50 µM) showed no cytotoxicity on periodontal cells. It significantly reduced pro-inflammatory cytokine secretion and mitochondrial ROS in P. gingivalis-infected epithelial cells. Proteome analysis on infected epithelial cells revealed modulation of HSP60 and Akt expression by IN44. In vivo, IN44 demonstrated anti-inflammatory effects in a mouse model of systemic inflammation induced by P. gingivalis, and it improved periodontal healing.

CONCLUSION

These findings suggest that PHBs may warrant consideration as therapeutic targets for periodontitis and possibly other inflammatory disorders.

Periodontitis, Metabolic Syndrome and Diabetes: Identifying Patients at Risk for Three Common Diseases Using the aMMP-8 Rapid Test at the Dentist's Office

Background/Objectives: This narrative review paper highlights the multifaceted influence of dysbiotic biofilm, genetic background, host response, and environmental factors on periodontitis. It explores the roles of type I and II diabetes mellitus, gestational diabetes, and metabolic syndrome in the progression of periodontitis, drawing insights from various empirical studies and theoretical perspectives. Methods: Relevant articles were sourced using keywords in databases like PubMed/Medline, Science Direct, Scopus, and Google Scholar. Additionally, this review examines the relationship between aMMP-8 levels and increased glycemic states, as well as varying degrees of periodontitis severity. Results: The biomarker active-matrix metalloproteinase-8 (aMMP-8), produced by polymorphonuclear leukocytes (PMN), is highlighted as a reliable indicator of ongoing connective tissue degradation. Dysfunctions in PMN activity, accumulation of advanced glycation end products (AGE), and oxidative stress aggravate the periodontal inflammatory response and complications of diabetes. Traditional diagnostics of periodontitis do not provide sufficient information about the current or future disease initiation or activity of periodontitis. Conclusions: The implications of this review point to the need for monitoring periodontal health by utilizing innovative strategies like aMMP-8 point-of-care testing, using oral rinse for screening and treatment monitoring, and harnessing the potential of supportive treatments like low-dose doxycycline and light-activated mouth rinses for restoring periodontal health. Its expression in oral fluids is a promising diagnostic tool to differentiate periodontitis from gingivitis and healthy periodontium, especially when associated with systemic diseases, fostering greater collaboration among healthcare professionals.

Gingival crevicular fluid Bax, Bcl-xl, interleukin-22, and transforming growth factor beta 1 levels in stage III periodontitis

BACKGROUND

Intrinsic apoptosis plays a critical role in immune defense and inflammation. Its dysregulation is involved in various chronic diseases. The B-cell lymphoma 2 (Bcl-2) family primarily mediates this mitochondrial pathway. This study aimed to investigate the proapoptotic Bcl-2-associated X protein (Bax) and antiapoptotic B-cell lymphoma-extra large (Bcl-xl) levels and their association with interleukin-22 (IL-22) and transforming growth factor beta 1 (TGF-β1) in the gingival crevicular fluid (GCF) of patients with periodontitis.

METHODS

A total of 75 systemically healthy nonsmokers were enrolled, of whom 23 had stage III periodontitis, 26 had gingivitis, and 26 were periodontally healthy. Whole-mouth clinical periodontal measurements were recorded. Bax, Bcl-xl, IL-22, and TGF-β1 levels in the GCF were determined by enzyme-linked immunosorbent assay (ELISA). Data were analyzed using nonparametric statistical tests.

RESULTS

The periodontitis group had significantly lower GCF Bax levels than the gingivitis group (p < 0.05). The periodontitis and gingivitis groups had higher GCF Bcl-xl levels than the periodontally healthy group (p < 0.05). GCF IL-22 levels were similar in all groups (p > 0.05). The periodontitis group had lower GCF TGF-β1 levels than the gingivitis and periodontally healthy groups (p < 0.05). The diseased groups had a lower GCF Bax/Bcl-xl ratio than the healthy controls (p < 0.05). IL-22 was positively correlated with Bax (p < 0.05).

CONCLUSIONS

This is the first study investigating GCF Bax and Bcl-xl levels in periodontal health and disease. Increased GCF Bcl-xl levels and a decreased Bax/Bcl-xl ratio in stage III periodontitis implicate that those apoptotic proteins may be involved in the pathogenesis of periodontal disease. Further studies are needed to enlighten the possible role of Bax and Bcl-xl and their association with IL-22 and TGF-β1 in periodontal diseases.

PLAIN LANGUAGE SUMMARY

A type of cell death called intrinsic apoptosis plays an important role in the body's defense system, and its dysregulation is linked to different human diseases. The B-cell lymphoma 2-associated X protein (Bax) and B-cell lymphoma-extra large (Bcl-xl) are apoptosis-related proteins, which promote and inhibit cell death, respectively. This study aimed to investigate Bax and Bcl-xl levels and their association with the signaling proteins interleukin-22 (IL-22) and transforming growth factor beta 1 (TGF-β1) in the gingival crevicular fluid (GCF), which accumulates around the necks of the teeth of patients suffering from gum diseases such as gingivitis and periodontitis. Clinical parameters were recorded and GCF was collected. Bax, Bcl-xl, IL-22, and TGF-β1 levels were measured by biochemical assay in periodontally healthy individuals who had healthy gums (n = 26) and patients with periodontitis (n = 23) and gingivitis (n = 26). Periodontitis patients had lower Bax levels than gingivitis patients. Periodontitis and gingivitis patients had higher Bcl-xl levels and a lower Bax/Bcl-xl ratio than periodontally healthy individuals. IL-22 was positively correlated with Bax. The present findings suggest that the apoptotic regulatory molecules may be involved in the development of gum diseases, highlighting the need for further research in this area.

The translational potential of inflammation-induced skin blister human models in exploring the pathogenesis of periodontitis and its systemic health implications

Periodontitis is a highly prevalent chronic disease. Despite decades of extensive research on the topic, a complete understanding of its immunopathogenesis, especially when linked to other inflammatory comorbidities, is lacking. Ex vivo human and in vivo animal experiments have shown the host inflammatory response's crucial role in both the disease's onset and its systemic implications. These approaches, however, remain questionable when translating these findings into real-world scenarios linked to periodontitis. A clear need for new in vivo human models is discussed, especially within the context of understanding the host response to key pathogens linked to periodontitis, such as Porphyromonas gingivalis (P. gingivalis). Therefore, a skin blister model was employed to describe the stages of the host immune response in humans after challenges by microbial and/or sterile insults. A novel human challenge model using UV-killed P. gingivalis holds promise in producing new evidence and bridging the gap of the host response to periodontitis and its links with other common chronic diseases.

Oral biofluid levels of Activin-A and interleukin-1beta in stage III periodontitis

OBJECTIVES

Activin-A belongs to the transforming growth factor-beta superfamily and is a multifunctional cytokine that plays a role in inflammation, immune response, tissue repair and regeneration. Proinflammatory cytokine interleukin-1beta (IL-1β) can increase Activin-A expression in various cell types. This study aims to evaluate gingival crevicular fluid (GCF) and salivary Activin-A and IL-β levels in stage III periodontitis.

MATERIALS AND METHODS

23 patients with stage III periodontitis, 26 with gingivitis and 26 periodontally healthy individuals were included. Full-mouth clinical periodontal indices were recorded, unstimulated whole saliva and GCF samples were obtained, Activin-A and IL-1β total amounts were determined by ELISA. Statistical comparisons were performed using non-parametric tests. Receiver operating characteristics curve was used for estimating the area under the curve (AUC).

RESULTS

Periodontitis group exhibited significantly lower GCF Activin-A levels but higher IL-1β levels than the periodontally healthy group (p < 0.05). Gingivitis group had similar GCF Activin-A and IL-1β levels to the periodontitis and periodontally healthy groups (p > 0.05). Salivary Activin-A and IL-1β concentrations were similar among study groups (p > 0.05). GCF Activin-A level showed an excellent diagnostic performance (an AUC value of 0.82 with 87% sensitivity) to discriminate periodontitis from periodontal health.

CONCLUSIONS

For the first time, this study demonstrated oral biofluid levels of Activin-A in periodontal health and diseases. Within the limits of the study, it might be suggested that diseased sites in periodontitis are associated with reduced Activin-A and increased IL-1β levels in GCF.

CLINICAL RELEVANCE

Reduced GCF Activin-A levels and the accompanying increase in IL-1β might be associated with diseased sites in stage III periodontitis.

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.

Effects of host modulation through omega-3 dietary supplementation on inflammatory outcomes in periodontitis: a scoping review

OBJECTIVE

Inflammation causes the progressive destruction of the supporting tissues around teeth in patients with periodontitis. Therefore, this study aimed to investigate the immunological effects of omega-3 polyunsaturated fatty acids (n-3 PUFAs) as adjunctive therapy in patients with periodontal disease and identify potential biomarkers for the disease.

METHODS

This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to investigate the impact of omega-3 therapy with or without acetylsalicylic acid on the immunological parameters of periodontal treatment. Eligible studies included those conducted on patients with normoglycemia and diabetes, published after 2002 in English, and containing relevant keywords. The exclusion criteria included pre-2002 publications, literature reviews, animal studies, and articles without immunological analysis. This review involved careful study selection by two double-blind researchers using the Rayyan software, with data extraction and analysis performed by the third and fourth reviewers.

RESULTS

Seven randomized clinical trials that compared control/placebo and n-3 PUFA groups or the follow-ups of the n-3 PUFA groups were included. The concentration of inflammatory cytokines was reduced following dietary supplementation with n-3 PUFA in the reviewed studies. Specifically, IL-1β, TNF-α, IL-6, and RANKL levels were reduced after dietary supplementation with n-3 PUFA as an adjunctive therapy for periodontitis. Changes in inflammatory outcomes were associated with the clinical benefits of periodontitis. However, significant divergence in the evaluated inflammatory markers, samples, and methods impairs direct comparisons and quantitative analyses in the available literature.

CONCLUSION

This study highlights the need for clinical trials to advance our understanding and assessment of inflammatory outcomes in patients with periodontitis.

Insights into the variations in microbial community structure during the development of periodontitis and its pathogenesis

OBJECTIVE

To characterize the subgingival microbiota in subjects with stage I/II periodontitis (moderate periodontitis, MP), stage III/IV periodontitis (severe periodontitis, SP), and periodontal health (PH) at the same probing depth (PD) (shallow ≤ 3 mm, moderate 4-6 mm, or deep ≥ 7 mm), and to investigate the changes associated with probing depth progression.

MATERIALS AND METHODS

100 subgingival plaque samples were collected from 50 subjects (16 MP, 17 SP and 17 PH), forming six groups: PHS (PH, shallow), MPS (MP, shallow), MPM (MP, moderate), SPS (SP, shallow), SPM (SP, moderate), and SPD (SP, deep). Samples were analyzed using high-throughput sequencing.

RESULT

The subgingival microbiome showed significant differences associated with both PD and periodontitis stage (p < 0.05). With increasing PD, alpha diversity initially increased and then decreased. Pathogenic genera like Fusobacterium, Filifactor, and Porphyromonas increased, while health-associated genera like Streptococcus and Haemophilus decreased. At shallow sites, the PHS, MPS, and SPS groups showed similar community structure. At moderate and deep sites, the SPM and SPD groups exhibited significant differences in community structure compared to the MPM group, with the SPM and SPD groups showing decreased abundances of Actinomyces and increased abundances of Treponema. The microbial co-networks in the SPD and SPM groups exhibited greater complexity and connectivity and were more resilient to random microbial or node removal.

CONCLUSIONS

The subgingival microbiome shows strong associations with PD and periodontitis stage.

CLINICAL RELEVANCE

Once periodontitis progresses to stage III/IV, reconstructing a healthy subgingival microbiome may be challenging, emphasizing the importance of early prevention.

Microbial- and host immune cell-derived extracellular vesicles in the pathogenesis and therapy of periodontitis: A narrative review

Periodontitis is a chronic inflammatory disease caused by dysbiotic biofilms and destructive host immune responses. Extracellular vesicles (EVs) are circulating nanoparticles released by microbes and host cells involved in cell-to-cell communication, found in body biofluids, such as saliva and gingival crevicular fluid (GCF). EVs are mainly involved in cell-to-cell communication, and may hold promise for diagnostic and therapeutic purposes. Periodontal research has examined the potential involvement of bacterial- and host-cell-derived EVs in disease pathogenesis, diagnosis, and therapy, but data remains scarce on immune cell- or microbial-derived EVs. In this narrative review, we first provide an overview of the role of microbial and host-derived EVs on disease pathogenesis. Recent studies reveal that Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans-derived outer membrane vesicles (OMVs) can activate inflammatory cytokine release in host cells, while M1 macrophage EVs may contribute to bone loss. Additionally, we summarised current in vitro and pre-clinical research on the utilisation of immune cell and microbial-derived EVs as potential therapeutic tools in the context of periodontal treatment. Studies indicate that EVs from M2 macrophages and dendritic cells promote bone regeneration in animal models. While bacterial EVs remain underexplored for periodontal therapy, preliminary research suggests that P. gingivalis OMVs hold promise as vaccine candidates. Finally, we acknowledge the current limitations present in the field of translating immune cell derived EVs and microbial derived EVs in periodontology. It is concluded that microbial and host immune cell-derived EVs have a role in periodontitis pathogenesis and hence may be useful for studying disease pathophysiology, and as diagnostic and treatment monitoring biomarkers.

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.

Proteome-Wide Mendelian Randomisation Identifies Causal Links of Plasma Proteins With Periodontitis

OBJECTIVE

Periodontitis is a complex and multifactorial disease and it is challenging to decipher its underlying causes and mechanisms. This study attempted to explore potential circulating proteins in connection to periodontitis through proteome-wide Mendelian randomisation (MR).

METHODS

We analysed 1722 circulating proteins to identify prospective drug targets for tackling periodontitis, using the genomic dataset from the FinnGen study. Two-sample MR was conducted to evaluate the bidirectional relationship between circulating proteins and periodontitis risk. A dataset from the UK Biobank was used to validate the findings. Single-cell analysis was performed to assess the cellular expression of the identified proteins within gingival tissues.

RESULTS

MR analyses found that genetically predicted circulating levels of von Willebrand factor A domain-containing 1 (von Willebrand factor A domain containing 1 [VWA1], odds ratios: 0.94, 95% CI 0.92-0.97, P = 1.28 × 10-5) were inversely associated with periodontitis. In contrast, the level of growth differentiation factor 15 (growth differentiation factor 15 [GDF15], odds ratios: 1.05, 95% CI 1.02-1.07, P = 2.12 × 10-5) might be associated with an increased risk of periodontitis. Single-cell analysis indicated that VWA1 was primarily expressed in endothelial cells of healthy gingival tissues, while the main source of GDF15 was not derived from periodontal cells.

CONCLUSIONS

The present study suggests that certain plasma proteins like VWA1 and GDF15 may be potentially indicative of the risk and susceptibility to periodontitis. These proteins could possibly be the potential therapeutic targets for treating periodontitis, and further investigation is highly warranted.

Inflammation and immune response in the development of periodontal disease: a narrative review

We present this critical review with the aim of highlighting the current status of periodontal diseases, focusing on the relevance of host modulating agents and immune pathways, in addition to new complementary therapeutic approaches for the treatment of these pathologies. Periodontal diseases are prevalent pathologies worldwide and the main cause of edentulism in the adult population. Their pathogenesis seems to be based on a dysbiosis of the oral microbiota that interacts with the host's immune defenses and is responsible for the inflammatory/immune response, which would be modified by a number of conditions such as individual susceptibility, environmental and sociodemographic factors, certain systemic pathologies and the individual's genetic condition, among others. Numerous studies have reported on the complex web of inflammatory mediators in periodontal disease and their role in tissue destruction as well as in homeostatic imbalance. Precisely, the role of epigenetics as a modifier of the host genetic condition has captured research attention in recent years. Therefore, this mini-review first discusses an updated etiological hypothesis of periodontal disease and the roles of certain cytokines in the immune response. In addition, the latest therapeutic trends with new developments and future perspectives are summarized.

Inhibition of soluble epoxide hydrolase reverses bone loss in periodontitis by upregulating EMCN and inhibiting osteoclasts

BACKGROUND

Improving the microenvironment to augment endogenous regenerative potential has emerged as a fundamental concept for stimulating and expediting periodontal tissue repair and regeneration. Previous studies have demonstrated that TPPU, a soluble epoxide hydrolase inhibitor (sEHi), mediates the suppression of inflammatory bone loss in periodontitis models. However, the underlying mechanisms remain largely elusive.

METHODS

In this study, we constructed a human umbilical vein endothelial cell (HUVEC) and periodontal ligament stem cell (PDLSC) coculture system in vitro and tested the anti-inflammatory effect of TPPU under inflammatory conditions. The roles of HIF-1α and Endomucin (EMCN) in the anti-inflammatory effects of TPPU were analyzed. The effects of TPPU on osteogenesis and osteoclastogenesis in cocultured cells were examined. The in vivo periodontitis model further verified the effects of TPPU on inhibiting neutrophil adhesion and inflammation and inhibiting osteoclasts.

RESULTS

Our in vitro experiments demonstrated that TPPU enhances the interaction between mesenchymal stem cells and vascular endothelial cells to enhance anti-inflammatory and osteogenic differentiation effects and revealed a new anti-inflammatory mechanism of TPPU involving the upregulation of EMCN in endothelial cells to prevent lymphocyte recruitment. We also confirmed that TPPU inhibits osteoclast activity. Our in vivo findings showed that TPPU inhibits osteoclast activity and neutrophil adhesion and enhances periodontal tissue repair and regeneration.

CONCLUSIONS

TPPU promotes local regeneration in periodontitis by inhibiting inflammation and bone resorption. Thus, targeting soluble epoxide hydrolase represents an endogenous regenerative strategy for periodontitis treatment.

Thermosensitive hydrogel doped with osteoconductive fillers for the treatment of periodontitis periapicalis chronica: from synthesis to clinical trial

Herein, a chitosan-based thermosensitive hydrogel (CH) containing hydroxyapatite (HAp), poly(lactic acid) (PLDLLA) or their mixture is proposed as an innovative, biomimetic composition with antimicrobial and bone-forming properties for guided bone regeneration. The modified hydrogels were synthesized and characterized to verify their suitability for the treatment of periodontitis periapicalis chronica. Compared to the unmodified hydrogel, both CH_HAp and CH_PLDLLA revealed improved mechanical properties, as evidenced by rotational rheology. FTIR analysis proved that no chemical interplay existed between the components. All the tested samples displayed no cytotoxicity against osteoblast-like cell culture and confirmed antimicrobial features, both crucial from an application perspective. Radiation sterilization dosage was tailored for the tested samples to maintain sterility for a minimum of 8 weeks of storage and limit crosslinking of the samples. Finally, the hydrogel was used in a clinical trial to treat a patient with chronic inflammation of periapical tissues in teeth 26 and 27. The medical procedure proved the safety, nontoxicity, non-allergenicity, and, most importantly, bone-forming properties of the hydrogel formulation. The kinetics of new bone formation was analyzed in-depth using graphical cross-sections of anatomical structures obtained from pre- and post-operative CBCT scans.

Stannous fluoride protects gingival keratinocytes against infection and oxidative stress by Porphyromonas gingivalis outer membrane vesicles

Objective

To determine whether outer membrane vesicles (OMVs) of the periodontal pathogen Porphyromonas gingivalis (P. gingivalis) can infect gingival keratinocytes and stimulate reactive oxygen species (ROS) production, and to assess whether stannous fluoride (SnF2), stannous chloride (SnCl2) or 0.454% SnF2 toothpaste diluents can inhibit OMV infection.

Methods

OMVs were isolated from P. gingivalis culture and their morphology was characterized using scanning electron microscopy and transmission electron microscopy. OMVs were harvested, separated from parent bacteria, labeled with fluorescent probes, and added to proliferating gingival keratinocytes. Infection was monitored by measuring uptake of fluorescence. Free radicals and ROS were quantified by adding a separate CellROX fluorescent probe following 24 h incubation with OMVs, and automated fluorescence imaging was used to assess ROS generation rates. A dose response range of SnF2 and SnCl2 concentrations as well as 0.454% SnF2 toothpaste dilutions were added to OMVs to examine their potential to neutralize OMV infectivity and protect gingival keratinocytes from development of oxidative stress. The mechanism of SnF2 inhibition of OMV infection was studied by binding SnF2 with purified lipopolysaccharides (LPS) from the bacterial culture and examining the binding of stannous to LPS using mass spectrometry.

Results

Large numbers of OMVs were formed in P. gingivalis culture medium. They were purified along with isolating soluble LPS. Fluorescence imaging revealed that OMVs infected gingival keratinocytes and promoted oxidative stress in a dose-dependent manner. SnF2, SnCl2, and SnF2 toothpaste inhibited OMV infectivity (p < 0.05) and likewise protected gingival keratinocytes from oxidative stress (p < 0.05). Stannous precipitated LPS and OMVs from solution, forming insoluble aggregates easily isolated by centrifugation. Mass spectroscopic analysis revealed that stannous was bound to LPS in a one-to-one molecular equivalent ratio.

Conclusion

SnF2 not only kills bacteria, but also inhibits bacterial virulence factors, such as LPS and OMVs. SnF2, SnCl2 and stannous-containing toothpastes can precipitate OMVs and LPS to in principle protect gingival keratinocyte cells from infection leading to inflammation and oxidative stress.