Periodontitis: a polymicrobial disruption of host homeostasis

Advances of functional nanomaterials as either therapeutic agents or delivery systems in the treatment of periodontitis

Periodontitis is a common chronic inflammatory disease primarily caused by pathogenic microorganisms in the oral cavity. Without appropriate treatments, it may lead to the gradual destruction of the supporting tissues of the teeth. While current treatments can alleviate symptoms, they still have limitations, particularly in eliminating pathogenic bacteria, promoting periodontal tissue regeneration, and avoiding antibiotic resistance. In recent years, functional nanomaterials have shown great potential in the treatment of periodontitis due to their unique physicochemical and biological properties. This review summarizes various functionalization strategies of nanomaterials and explores their potential applications in periodontitis treatment, including metal-based nanoparticles, carbon nanomaterials, polymeric nanoparticles, and exosomes. The mechanisms and advances in antibacterial effects, immune regulation, reactive oxygen species (ROS) scavenging, and bone tissue regeneration are discussed in detail. In addition, the challenges and future directions of applying nanomaterials in periodontitis therapy are also discussed.

Proliferation and differentiation of human dental pulp stem cells on phosphorylated cellulose nanofiber scaffolds

Human dental pulp stem cells (hDPSCs) are a promising cell source for tooth regeneration therapies. However, conventional culture scaffold materials are often animal-derived, leading to immunogenicity concerns and limited availability. In this study, we explored phosphorylated cellulose nanofibers (P-CNFs), which have a fine fiber morphology and phosphate groups, as a novel scaffold material for cell culture. Immortalized hDPSCs were cultured on P-CNF scaffolds with different phosphate contents (0-1.42 mmol g-1) prepared by varying the molar ratio of urea and diammonium hydrogen phosphate and the reaction time. Cells cultured on unmodified CNFs exhibited poor adhesion and formed spheroids, indicating low bioadaptability. In contrast, P-CNF scaffolds with moderate phosphate content (0.54-0.78 mmol g-1) significantly improved cell adhesion; further increases in phosphate content decreased cell adhesion, indicating a strong dependence on phosphate content. Intriguingly, even in the absence of differentiation inducers, hDPSCs on P-CNF scaffolds with an optimal phosphate content of 0.78 mmol g-1 showed equal or higher expression of hard tissue marker genes compared to collagen scaffolds with differentiation inducers, suggesting that P-CNFs can directly promote hard tissue differentiation. These findings highlight plant-derived, animal-free P-CNFs as a promising biomaterial for advanced dental tissue engineering.

Regulatory T Cells promote osteogenic differentiation of periodontal ligament stem cells through the Jagged1-Notch2 signaling Axis

OBJECTIVES

This study aimed to elucidate the role of regulatory T cells (Tregs) in promoting the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) and to investigate the underlying mechanisms involving Notch signaling.

METHOD

Tregs were isolated via fluorescence-activated cell sorting (FACS) and co-cultured with PDLSCs. Osteogenic differentiation was assessed through in vitro assays and in vivo transplantation experiments. Gene expression profiles were quantified using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analysis. A murine periodontitis model was used to validated therapeutic outcomes, with bone remodeling quantified by micro-CT and histology (H&E, Masson's staining). Immunophenotypic analysis of Jagged1 expression in Tregs and Notch2 receptor localization in PDLSCs were performed using flow cytometry and immunofluorescence microscopy, respectively. The role of immobilized Jagged1 in osteogenic differentiation was further evaluated, while Notch pathway inhibition was achieved via γ-secretase inhibitor DAPT in vitro.

RESULTS

Elevated levels of Th17 cells and Tregs were observed in peripheral blood samples from periodontitis patients, with a significantly increased Th17/Treg ratio (p < 0.01). In vitro, co-culturing Tregs with PDLSCs significantly enhanced PDLSC osteogenesis, as evidenced by increased ALP activity (p < 0.01), elevated expression of osteogenesis-related genes (Runx2 and Osterix; p < 0.01), and enhanced mineralization (Alizarin Red staining) (p < 0.01). In vivo, intravenous infusion of Tregs into a periodontitis mouse model reduced periodontal damage and promoted bone regeneration, as demonstrated by reduced CEJ-ABC distance and increased BV/TV ratio (p < 0.01). Mechanistically, Tregs expressed the Notch ligand Jagged1 and upregulated Notch2 receptor expression in PDLSCs, indicating activation of the Notch signaling pathway. Jagged1 promoted osteogenic differentiation of PDLSCs in a dose- and time-dependent manner. Inhibition of Notch signaling using DAPT reduced Tregs-mediated enhancement of PDLSC osteogenesis (p < 0.05).

CONCLUSION

These findings suggest that Tregs promote PDLSC osteogenic differentiation via Jagged1-Notch2 signaling, highlighting the therapeutic potential of modulating Tregs and Notch signaling for periodontal regeneration and bone tissue engineering.

CLINICAL SIGNIFICANCE

This study provides new insights into the complex interplay between immune modulation and stem cell differentiation, laying the foundation for potential Tregs-based therapeutic strategies for periodontal and bone tissue regeneration.

Macrophage membrane functionalized composite microspheres promote bone regeneration in periodontitis via manipulating inflammation reversing-osteogenesis coupling

Periodontitis is characterized by inflammation and alveolar bone loss, primarily caused by immune cells activated by oral bacteria, leading to an imbalance between osteogenesis and bone resorption. Traditional treatments have limited efficacy, which has led to the exploration of regulating the immune microenvironment and utilizing tissue engineering methods as new research directions. Our study demonstrates that macrophage membranes, activated by LPS and IFN-γ, can effectively neutralize inflammatory factors. By coating the poly-L-lysine (PLL) modified poly (lactic-co-glycolic acid) (PLGA)/β-TCP microspheres with such macrophage membrane vesicles, the MM@PPT microspheres regulate intercellular responses by inhibiting macrophage M1 polarization and osteoclast differentiation, promoting M2 polarization, and enhancing osteogenic differentiation of bone marrow stromal cells (BMSCs) even in an inflammatory environment. By injecting the MM@PPT into sites of periodontitis induced bone resorption, it is found that they can effectively promote bone regeneration by modulating the immune-regeneration microenvironment. This work not only highlights the potential of MM@PPT microspheres in promoting alveolar bone regeneration but also provides insights into how these microspheres modulate cell behavior and interactions. The findings of this study offer novel therapeutic strategies for promoting alveolar bone repair in periodontitis.

An Off-the-Shelf Artificial Blood Clot Hydrogel Neutralizing Multiple Proinflammatory Mediators for Pro-Regenerative Periodontitis Treatment

Periodontitis is a destructive and chronic inflammatory disease initiated and sustained by multiple proinflammatory mediators. Current therapies mainly deal with bacteria elimination, but directly addressing the over-accumulated multiple inflammatory mediators in the periodontal microenvironment still remains a substantial challenge for regenerative periodontitis treatment. Herein, inspired by blood coagulation, an off-the-shelf artificial blood clot hydrogel encapsulated with platelet-rich plasma (PRP) is reported to mitigate the deteriorative inflammatory environment in periodontitis. The hydrogel (CCS-RSF@PRP) with a hierarchical fibers-interwoven network structure, in which the activated platelets are enriched, is structurally similar to the native blood clot. Functionally, in addition to the function of enriching and releasing growth factors, CCS-RSF@PRP can remarkably scavenge reactive oxygen species (ROS), neutralize endotoxin lipopolysaccharide (LPS), and proinflammatory cytokines (TNF-α, IFN-γ and IL-1β), inhibit M1 macrophage polarization and induce M2 macrophage polarization, thus blocking the chronic inflammatory feedback loop in the periodontitis. In rat periodontitis model, CCS-RSF@PRP hydrogel significantly expedits the repair of periodontium by normalizing the periodontal immune-environment. The work highlights the importance of local immunomodulation in the treatment of periodontitis, and the engineered PRP-derived hydrogel can mimic and expand the structure and function of native blood clot, holding great promise in treating chronic inflammatory diseases.

Isochlorogenic Acid A Attenuated Periodontitis by Inhibiting Inflammation via ACE/PGK1/STAT1 Signaling

The purpose of the present study was to evaluate the effect of isochlorogenic acid A (IAA) on periodontitis and explore its potential mechanism. A ligature/LPS procedure was employed to induce periodontitis in rats. LPS-induced HPDLF was used as the in vitro model. Bioinformatic analyses indicated that angiotensin-converting enzyme (ACE) might be the target of IAA in periodontitis. PGK1/STAT1 might be the related molecules of ACE. Treatment with IAA inhibited inflammatory cytokines, inflammatory molecule transcriptions in gingival tissues and HPDLFs. MicroCT, H&E, TRAP and Runx2 staining showed that IAA relieved periodontitis. Immunofluorescence observation and WB revealed that IAA inhibited ACE/PGK1/STAT1 in dental papilla, parodontium, gingival tissues and HPDLFs. IAA suppressed glycolysis, mitochondrial fission, oxidative stress and promoted oxidative phosphorylation, mitochondrial fusion. The application of the ACE-overexpression plasmid, PGK1 SiRNA, the ACE inhibitor captopril, the PGK1 inhibitor NG52 suggested that ACE and PGK1 were involved in IAA-mediated anti-inflammatory response. Molecular docking, molecular dynamics, DARTS and CETSA indicated that IAA might combine with ACE. It was also found that MYC governed ACE transcription. The Y195 residue of PGK1 was conservative and critical for the combination between PGK1 and ACE. ACE and PGK1 were also upregulated in gingival tissues of periodontitis patients. In conclusion, IAA ameliorated periodontitis by inhibiting inflammation via ACE/PGK1/STAT1 signaling.

Microbial Markers for Diagnosis and Risk Assessment for Periodontal Diseases: A Systematic Literature Search and Narrative Synthesis

AIM

To examine the accuracy of microbiological biomarkers in diagnosing periodontal diseases, specifically addressing three focus questions: (FQ1) distinguishing health from disease; (FQ2) predicting disease progression; and (FQ3) assessing treatment outcomes.

MATERIALS AND METHODS

A PRISMA-guided search in MEDLINE, EMBAS and WEB OF SCIENCE included cross-sectional and longitudinal studies (e.g., randomised controlled trials, cohort studies) with ≥ 20 participants per group. Eligible studies involved individuals diagnosed with periodontal health, gingivitis or periodontitis, based on well-defined clinical criteria, and utilised microbiological analyses of oral fluids and/or dental plaque. Diagnostic accuracy had to be evaluated using sensitivity, specificity or area under the receiver operating characteristic (ROC) curve (AUC), or alternatively, data for their computation had to be provided.

RESULTS

Thirty-one studies were included, mostly cross-sectional or case-control, with significant variability in sampling sites, microbial analyses and diagnostic definitions, complicating direct comparisons. Frequently investigated biomarkers included Aggregatibacter actinomycetemcomitans (JP2 genotype), Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola. The highest diagnostic accuracy (AUC > 0.95) was achieved through composite microbiome-based metrics such as the subgingival microbial dysbiosis index. However, methodological heterogeneity and inconsistent criteria limited reliability.

CONCLUSION

Although microbiological biomarkers hold promise for periodontal disease diagnostics and monitoring, current evidence is insufficient for clinical implementation. Future research should standardise methodologies, sampling protocols and diagnostic criteria to ensure robust validation and facilitate integration into precision dentistry.

Performance Validation of Fabricated Nanomaterial-Based Biosensor for Matrix Metalloproteinase-8 Protein Detection

Matrix metalloproteinase-8 (MMP-8) is a crucial collagenase enzyme that primarily degrades type I collagen and extracellular glycoproteins, playing a significant role in the pathological processes of periodontal disease. It can serve as a biomarker for early detection and screening of the disease through advanced biosensor technology. The aim of this study was to fabricate and validate the performance of a nanomaterial-based biosensor for detecting MMP-8 protein.The screen-printed gold electrode was modified with a thin film of 11-mercaptoundecanoic acid using the self-assembled monolayer technique. A biosensor was then created with N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide to form ester bonds, followed by the immobilization of the antibody MMP-8 and blocking of nonspecific binding. The performance characteristics of a biosensor for detecting MMP-8 concentrations, ranging from 1 to 50 ng/mL, were evaluated using electrochemical techniques with data analysis performed using the NOVA software. Enzyme-linked immunosorbent assay (ELISA) was used as a control.The results were expressed as mean values ± standard deviation. The coefficient of determination (R 2) was calculated based on the obtained calibration curve.Electrochemical measurements revealed that the peak current after modifying the thin film on the electrode was lower than the bare electrode. Characterization of biosensors showed an increase in response compared to the previous step. Differential pulse voltammetry measurements indicated that the peak current for MMP-8 concentrations ranging from 1 to 50 ng/mL increased proportionally with concentration. The biosensor demonstrated high sensitivity, with a correlation coefficient of R 2 = 0.953 when compared to ELISA (R 2 = 1).A biosensor utilizing nanomaterials has been successfully fabricated for the detection of the MMP-8 protein with high sensitivity. Subsequent research should prioritize the evaluation of its performance in clinical patients alongside an assessment of its specificity and stability. The objective was to advance this biosensor as a reliable diagnostic tool for the screening of periodontitis.

Annexin A2 Contributes to Release of Extracellular Vimentin in Response to Inflammation

Vimentin, an abundant intracellular cytoskeletal protein, is secreted into the extracellular space, where it can amplify tissue destruction in inflammatory diseases. The mechanisms by which inflammation promotes the release of extracellular vimentin (ECV) are not defined. In human subjects, we found > twofold higher levels of ECV in gingival crevicular fluid from periodontitis sites with inflammation compared with healthy sites. In cultures of human gingival fibroblasts (hGFs) treated with 1% serum or IL-1β (10 ng/mL) to model tissue injury or inflammation, respectively, we found that 1% serum increased ECV release > 11-fold while IL-1β further enhanced release 17-fold. Mass spectrometry of vimentin immunoprecipitates identified Annexin A2 (AnxA2), a Ca2+-dependent phospholipid-binding protein, as a potential binding protein of ECV, which was confirmed by immunoprecipitation of cultured hGFs and immunostaining of inflamed human gingiva. IL-1β treatment enhanced the abundance of AnxA2 and vimentin in membrane fractions prepared by sucrose gradients of hGF lysates. IL-1β increased colocalization of ECV and AnxA2 at the outer aspect of the plasma membrane of intact hGFs. Knockdown of AnxA2 with siRNA or inhibition of the unconventional secretory pathway reduced ECV release from hGFs. These findings indicate that the production of ECV by hGFs in response to inflammation is mediated by an AnxA2-dependent, unconventional secretory pathway that may play a role in amplification of the inflammatory response.

Interaction between Infection of Porphyromonas gingivalis, A Keystone Microbe of Oral Microbiome, and Serum Levels of Lutein/Zeaxanthin Is Associated with Risk for Age-related Macular Degeneration

Porphyromonas gingivalis (P. gingivalis) functions as a catalyst bacterium in the development of periodontitis, and the serum antibody level against P. gingivalis is considered a surrogate marker for the activity level of periodontopathic microbiome. The chronic systemic inflammation induced by P. gingivalis elevates the risk of various systemic and neurodegenerative disorders, including atherosclerosis, diabetes, and Alzheimer's disease. Although the connection between human microbiome and age-related macular degeneration (AMD) remains relatively unexplored, it is noteworthy that AMD shares risk factors and etiological mechanisms with diseases related to P. gingivalis. To investigate the potential association between periodontopathic microbiome and AMD occurrence, we conducted a candidate microbe approach case-control study. Our hypothesis was tested by examining the correlation between serum P. gingivalis immunoglobulin G (IgG) levels and AMD. Comparing the lowest IgG category (≤ 57 enzyme-linked immunosorbent assay units (EU)) with higher categories revealed escalating risks: the second higher category (58-65 EU) conferred almost a 30% increased risk (odds ratio (OR) = 1.28, 95% confidence interval (CI): 1.17 to 1.4), the third higher category (66-119 EU) conferred nearly a 60% increase (OR = 1.58, 95% CI: 1.46 to 1.72), and the highest category (> 119 EU) conveyed over a two-fold risk (OR = 2.04, 95% CI: 1.62 to 2.58) of early AMD. Aligning with the notion that the microbiome composition is significantly shaped by the host's diet, our analysis indicates that sustaining elevated serum levels of lutein/zeaxanthin (≥ 0.35 μmol/L or ≥ 20 μg/dL) might potentially mitigate the P. gingivalis-related AMD risk by as much as 35% (P for interaction < 0.0001). Although the precise mechanism requires additional exploration, these findings suggest a connection between nutrition and oral microbiome, emphasizing their collective role in maintaining eye health.

SIGNIFICANCE STATEMENT

While our oral microbiome may impact eye health, nutritional factors could play a modulatory role in mitigating the associated risk.

Porphyromonas gingivalis outer membrane vesicles divert host innate immunity and promote inflammation via C4' monophosphorylated lipid A

Porphyromonas gingivalis (Pg) is a prevalent pathogen that promotes human periodontal disease (PD) and exacerbates systemic comorbidities such as atherosclerosis, rheumatoid arthritis, and Alzheimer's disease. Pg produces nonphosphorylated tetra-acylated lipid A (NPLA) in its outer membrane (OM) that evades host Toll-like receptor 4 (TLR4), inflammasome pathways, and cationic peptides, enhancing bacterial survival. Here, we show that Pg also releases outer membrane vesicles (OMVs) that engage and divert host cell TLR4, inflammasome, and LL-37 responses away from the microbe. We determined that Pg OMVs are enriched for C4' monophosphoryl lipid A (C4'-MPLA), an established agonist for TLR4-TRIF-IFNβ and inflammasome-IL-1β responses. Comparisons of Pg 381 and Pg 33277 stationary phase cultures revealed higher OMV production by Pg 381, which correlates with its higher proinflammatory pathogenicity. The cationic peptide, polymyxin B (PMB), which selectively binds lipid A C4'-phosphate, reduces OMV-stimulated HEK cell TLR4 activation and THP-1 cell IL-1β production, confirming the proinflammatory role for OMV-C4'-MPLA. Similar to PMB, the host defense peptide, LL-37, inhibits OMV-C4'-MPLA-dependent HEK cell TLR4 activation. PMB and LL-37 also blocked OMV-C4'-MPLA-driven TLR4 activation in human umbilical vein endothelial cells. Finally, wild-type Pg-containing OM-NPLA is highly resistant to LL-37 antimicrobial activity, whereas the ΔlpxF mutant bacterium, retaining OM-C4'-MPLA, is killed by the peptide. In summary, Pg escapes host TLR4 signaling, inflammasome activation, and LL-37 interaction by retaining immunoevasive OM-NPLA. Moreover, Pg dispenses proinflammatory OMV-C4'-MPLA, which engages and redirects those host defenses. We suggest that OMV-C4'-MPLA triggers elevated IFNβ and IL-1β cytokines, which typify PD comorbidities, and drive PD-related alveolar bone loss.

High-Frequency Ultrasound Characterization of Periodontal Soft Tissues Pre- and Post-Bacterial Inoculation

OBJECTIVE

Current diagnostic methods of inflammatory periodontal diseases, e.g., visual evaluation, periodontal probing, and radiographs, are either subjective or insensitive. Intra-oral high-frequency ultrasound was investigated to quantify inflammation by detecting tissue dimensional and perfusion changes.

METHODS

A cohort of 15-month-old mini-pigs, 4 female/male each, was analyzed. Pre-molars (PM) 3 and 4, as well as first molars (M1), were scanned. In bi-weekly time intervals all 4 quadrants were randomly enrolled and bacterial injection followed each quadrant scan in a weekly fashion. Soft tissue dimensions were obtained from B-mode images and statistically analyzed to identify correlations to inoculation time, i.e., response to bacterial loading, tooth type and sex, using analysis of variance and regression analysis. Color flow velocity and power-weighted color pixel density was obtained and statistically analyzed analogous to soft tissue.

RESULTS

Soft tissue thickness increased significantly post-inoculation at 1 and 2 mm below the free gingival margin for both genders and all observed teeth. The significance lasted for weeks 2, 4 and 6, except for female M1s (4 weeks). Color flow velocity was significantly higher compared with baseline for 6 weeks, except for male PM4 (2 weeks). Color flow power did not show significance for PM3 and 4, only in M1 (except male week 4). Significance also extended to tooth type and sex.

CONCLUSION

Periodontal tissue dimension and color flow velocity increased in correlation to bacterial inoculation. Further studies are needed to obtain an understanding of the underlying biology observed here. Eruption of dentition may have been a confounding factor for inflammation interpretation.

Oral and intestinal flora translocation and tumor development

ABSTRACT

Cancer metastasis is the leading cause of death in patients. In recent years, there has been a growing recognition of the role of tumor-associated microflora in tumor metastasis. The connection between oral and gut microflora and the tumor microenvironment has also been extensively studied. The migration of oral and gut microflora is closely associated with tumor development. Although there is awareness regarding the significant impact of microbial communities on human health, the focus on their relationship with host organisms, particularly those related to tumor-associated microflora, remains inadequate. As an integral part of the body, the host microflora is crucial for regulating the cancer risk and preventing tumor recurrence. The oral-gut axis plays an indispensable role in human immunity, and many types of cancers, such as colorectal, pancreatic, and breast, are significantly influenced by their internal microbial communities. However, further exploration into the mechanisms underlying the role of the intratumoral microflora in cancer is necessary to achieve a comprehensive understanding. We have summarized and analyzed related articles in PubMed. This article reviews the impact of the oral-gut axis on the human immune system, explores the relationship between the translocation of the oral and intestinal flora and the tumor microenvironment, analyzes the specific mechanisms involved in the translocation of the oral and intestinal microflora during the evolution and progression of tumors, and elaborates on the correlations between the occurrence and development of tumors and the changes in the microflora. Finally, a summary of these abovementioned points is provided.

Dimethyl Citraconate Alleviates Periodontitis via Activating the NRF2 Cascade

Nuclear factor erythroid 2-related factor 2 (NRF2) is a pivotal transcription factor that regulates redox signaling, playing a protective role in inflammation. Citraconate is verified as the strongest NRF2 agonist among its isomers. Dimethyl citraconate (DMC), an esterified derivative of citraconate, holds the potential for activating NRF2 and relieving inflammation. Here, we show that DMC is a strong NRF2-activating compound, stabilizing the intracellular NRF2 level and its nuclear translocation. DMC increases the expression levels of NRF2 downstream genes, thereby restricting the accumulation of reactive oxygen species and performing anti-inflammatory functions. The local administration of DMC effectively alleviates periodontal destruction in a ligation-induced periodontitis mouse model, elevating the NRF2 levels and downstream antioxidant enzymes. Moreover, the protective effect of DMC against periodontitis is absent in Nfe2l2-/- mice. Mechanically, DMC prolongs the half-life of NRF2 and facilitates its dissociation from KEAP1 (Kelch-like ECH-associated protein 1), which suggests that DMC interrupts the crosstalk between KEAP1 and NRF2. Collectively, our findings illustrate the role of DMC in activating NRF2 and ameliorating periodontal inflammation, suggesting its therapeutic potential for inflammation-related diseases.

Interleukin-37 reduces lipopolysaccharide induced matrix metalloproteinase-9 in gingival epithelial cells

BACKGROUND

In periodontal diseases, the recognition of pathogen-associated molecular patterns (PAMPs) triggers signaling cascades that lead to the release of matrix metalloproteinases (MMPs). Interleukin-37 (IL-37) is recognized as a key suppressor of the immune response. This study aimed to detect the expression and distribution of IL-37 in gingival tissues and analyze its suppressor role in MMP-9 in response to lipopolysaccharide (LPS)-stimulated gingival epithelial cells.

METHODS

Immunohistochemistry localized IL-37 in gingival tissues from periodontitis patients and healthy controls (N = 10). The induction of IL-37 expression by LPS was analyzed using the conditioned medium of gingival epithelial cells through enzyme-linked immunosorbent assay (ELISA). To determine the relevant MMP-9 levels in epithelial cells following exposure to LPS alone or in combination with IL-37, both quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA) were performed.

RESULTS

Cultured epithelial cells secreted significantly higher levels of IL-37 when stimulated with LPS compared to unstimulated controls. Both ELISA and qPCR showed that LPS stimulation significantly increased MMP-9 levels. However, co-culture with IL-37 markedly reduced LPS-induced MMP-9 expression at both the protein and mRNA levels. Furthermore, immunohistochemistry revealed increased IL-37 expression in periodontitis tissues, both in epithelial cells and connective tissue.

CONCLUSIONS

Gingival epithelial cells may contribute to tissue responses in periodontitis through the secretion of MMP-9 in response to PAMPs. Furthermore, IL-37 appears to have a potential role in modulating and reducing this response, as observed in the decreased MMP-9 expression following IL-37 co-stimulation.

Investigation of oral microbiome composition in elderly Chinese patients with hypertension: a cross-sectional study

Background

Hypertension is a prevalent metabolic disorder in the elderly, with its pathogenesis linked to gut microbiota dysbiosis. Recent studies suggested that oral microbiota may also play a role in hypertension development, yet its relationship with hypertension in the elderly remains underexplored.

Objective

This cross-sectional study aimed to examine the structure of the oral microbiota and its association with hypertension in elderly patients, providing insights into hypertension prevention and treatment.

Methods

A total of 206 subjects (60-89 years) were categorized into normal (CON) and hypertensive (HTN) groups, based on the Chinese Hypertension Guidelines. Saliva samples were analyzed using 16S rRNA gene sequencing.

Results

Oral microbiota composition was significantly influenced by blood pressure. At the phylum level, Synergistetes and Spirochaetes were more significantly abundant in the HTN group, while at the genus level Treponema and Leptothrix was higher, Actinomyces and Capnocytophaga were lower in HTN. Random Forest analysis identified 15 key microbiota as strong discriminators of HTN (AUC 0.74). Blood pressure was negatively correlated with Actinomycetes and positively correlated with Leptothrix. PICRUST2 analysis revealed elevated chlorinated compound degradation in HTN patients.

Conclusions

This study identified distinct oral microbiota in elderly hypertensive patients, highlighting the role of the oral microbiome in hypertension pathogenesis.

Natural and induced immune responses in oral cavity and saliva

This review comprehensively explores the intricate immune responses within the oral cavity, emphasizing the pivotal role of saliva in maintaining both oral and systemic health. Saliva, a complex biofluid, functions as a dynamic barrier against pathogens, housing diverse cellular components including epithelial cells, neutrophils, monocytes, dendritic cells, and lymphocytes, which collectively contribute to robust innate and adaptive immune responses. It acts as a physical and immunological barrier, providing the first line of defense against pathogens. The multifaceted protective mechanisms of salivary proteins, cytokines, and immunoglobulins, particularly secretory IgA (SIgA), are elucidated. We explore the natural and induced immune responses in saliva, focusing on its cellular and molecular composition. In addition to saliva, we highlight the significance of a serum-like fluid, the gingival crevicular fluid (GCF), in periodontal health and disease, and its potential as a diagnostic tool. Additionally, the review delves into the impact of diseases such as periodontitis, oral cancer, type 2 diabetes, and lupus on salivary immune responses, highlighting the potential of saliva as a non-invasive diagnostic tool for both oral and systemic conditions. We describe how oral tissue and the biofluid responds to diseases, including considerations to periodontal tissue health and in disease periodontitis. By examining the interplay between oral and systemic health through the oral-systemic axis, this review underscores the significance of salivary immune mechanisms in overall well-being and disease pathogenesis, emphasizing the importance of salivary mechanisms across the body.

Exploring the Non-Toxic Therapeutic Potential of Dioscorea communis in Combating Oral Pathogenic Bacteria and Their Effects on Hard and Soft Oral Tissues

Background/Objectives: Gingivitis and dental caries are oral diseases resulting from bacterial accumulation in dental plaque, leading to inflammation, tissue destruction and the demineralization of tooth structures. Dioscorea communis, due to its anti-inflammatory and antimicrobial properties, could be a new treatment candidate. Methods: This study evaluated the preventive and therapeutic effect of a D. communis berry juice paste, formulated at 3% and 7% concentrations, on gingivitis and dental caries, in 55 male SKH-hr2 hairless mice. Gingivitis and dental caries were induced by ligation of the upper left incisor and the paste was applied topically three times daily, five days a week. Treatment efficacy was assessed through clinical examinations, photo-documentation, histopathological analysis and FT-IR spectroscopy. Results/Conclusions: Preventive administration of D. communis 7% significantly delayed disease onset, while therapeutic effects on established conditions were limited. Both concentrations were non-toxic to gingival tissues and dental structures.

Effects of periodontal disease on the proteomic profile of the periodontal ligament

Periodontal disease affects over 1 billion people globally. This study investigated how periodontitis affects the protein profile of the periodontal ligament (PDL) in rats. Eight Holtzman rats were divided into control and experimental periodontitis groups. The PDL was isolated using laser capture microdissection and protein extracts were analyzed by mass spectrometry. Data analysis utilized specialized software, and Gene Ontology enrichment analysis identified significant protein functions. The data are available via ProteomeXchange with identifier PXD055817. Proteins such as SerpinB1, C5, and Lgals3 were validated through immunohistochemistry, and their gene expression was examined in an in vitro human PDL cell line. This study identified 1326 proteins, with 156 unique to the control group, 294 unique to the periodontitis group, and 876 common to both groups. Enrichment analysis revealed that proteins associated with the regulation of enzyme activity and RNA binding were significantly represented in the periodontitis group. There were increased levels of SerpinB1, C5, and Lgals3 in the periodontitis group based on proteomic and immunohistochemical analyses. Furthermore, these targets showed increased gene expression in stimulated human PDL cells. This study provides insights into the periodontitis-related alterations in the protein composition of the PDL and PDL cells, identifying both novel and previously known disease-associated proteins. SIGNIFICANCE: The periodontal ligament plays a crucial role in oral functions by providing structural support to the tooth. Due to the presence of undifferentiated mesenchymal cells, research into its regenerative capacity is ongoing. Pathological conditions can affect these functions and protein composition. Currently, there is a lack of comprehensive research specifically focusing on evaluating the periodontal ligament in both healthy and diseased states. This pioneering study screened for protein alterations and the mechanisms related to periodontitis. The possibility of using proteomic analysis to evaluate the protein alterations that occur in periodontitis, a disease with a high global incidence, could provide therapeutic targets and new biomarkers for future clinical studies.

A complex of NLRP3 with caspase-4 is essential for inflammasome activation by Tannerella forsythia infection

Periodontitis, a chronic inflammatory disease of periodontal tissue, is often associated with a group of pathogenic bacteria known as the "red complex", including Tannerella forsythia. Previous papers showed that T. forsythia induces many kinds of inflammatory cytokines including interleukin (IL)-1β regulated by inflammasome activation. However, the physiological function of periodontitis and the mechanism to induce inflammasome activation by T. forsythia infection are poorly understood. In this study, we demonstrate that the Nod-like receptor pyrin domain containing 3 (NLRP3) and caspase-4 are essential for inflammasome activation by T. forsythia infection, playing a crucial role in IL-1β maturation in THP-1 cells. We also showed that the knockout of ASC or Gasdermin D suppresses pyroptotic cell death. Moreover, co-immunoprecipitation assays confirmed the formation of a complex involving caspase-4, NLRP3, and ASC following T. forsythia infection. Additionally, reactive oxygen species production was identified as a key factor in caspase-4-mediated NLRP3 inflammasome activation by T. forsythia infection. These results enhance our understanding of inflammasome activation in response to T. forsythia infection and provide new insights into the pathogenic mechanisms of periodontitis.

Emerging oral Treponema membrane proteins disorder neutrophil phosphoinositide signaling via phosphatidylinositol-4-phosphate 5-kinase

Background

Periodontitis (PD) is a group of inflammatory pathologies characterized by destruction of the tooth-supporting tissues. During PD, dysbiosis of the oral biofilm disrupts the host immune response and supports growth of pathogenic bacteria including the spirochetes Treponema denticola (Td), T. maltophilum (Tm), and T. lecithinolyticum (Tl). The outer membrane protein of Td, Msp, perturbs the function of neutrophils by modulating phosphoinositide (PIP) signaling. While Tm and Tl have similar outer membrane proteins, MspA and MspTL respectively, little is known of how these proteins affect neutrophil function.

Methods

This study examines putative mechanisms by which T. maltophilum MspA and T. lecithinolyticum MspTL inhibit neutrophil chemotaxis. Murine bone marrow neutrophils were treated with recombinant MspA or MspTL protein. Protein phosphorylation was assessed via immunoblot, phosphate release by malachite green assay, and PTEN and SHIP phosphatase activity through immunoprecipitation, enzymatic assays, and chemical inhibition. PIP quantification was assessed by immunofluorescence microscopy and Mass ELISAs, while small GTPase activity was measured with G-Protein Activation Assays. Neutrophil F-actin localization was determined through immunofluorescence.

Results

MspA and MspTL increase phosphate release in neutrophils, but unlike Msp, they do not affect PTEN or SHIP activity, despite modulating cellular levels of multiple PIP species [PI(3,4)P2, PI(4,5)P2, and PIP3]. Overall, MspA and MspTL differentially affected the metabolism of individual PIP species, but both increased PI(4,5)P2 levels in a PIP5K-dependent manner. Downstream effects of disrupted PIP signaling included inhibition of Akt and Rac1 activation and increased cortical F-actin localization.

Conclusions

Understanding distinct mechanistic relationships between novel Msp proteins and neutrophils provides important insight into how these understudied bacteria promote periodontitis progression.

New Advances in Periodontal Functional Materials Based on Antibacterial, Anti-Inflammatory, and Tissue Regeneration Strategies

With the global population aging, awareness of oral health is rising. Periodontitis, a widespread bacterial infectious disease, is gaining attention. Current novel biomaterials address key clinical issues like bacterial infection, gum inflammation, tooth loosening, and loss, focusing on antibacterial, anti-inflammatory, and tissue regeneration properties. However, strategies that integrate the advantages of these biomaterials to achieve synergistic therapeutic effects by clearing oral biofilms, inhibiting inflammation activation, and restoring periodontal soft and hard tissue functions remain very limited. Recent studies highlight the link between periodontitis and systemic diseases, underscoring the complexity of the periodontal disease. There is an urgent need to find comprehensive treatment plans that address clinical requirements. Whether by integrating new biomaterials to enhance existing periodontal treatments or by developing novel approaches to replace traditional therapies, these efforts will drive advancements in periodontitis treatment. Therefore, this review compares novel biomaterials with traditional treatments. It highlights the design concepts and mechanisms of these functional materials, focusing on their antibacterial, anti-inflammatory, and tissue regeneration properties, and discusses the importance of developing comprehensive treatment strategies. This review aims to provide guidance for emerging periodontitis research and to promote the development of precise and efficient treatment strategies.

SLC30A4-AS1 Mediates the Senescence of Periodontal Ligament Stem Cells in Inflammatory Environments via the Alternative Splicing of TP53BP1

Periodontal ligament stem cells (PDLSCs) are key cells that suppress periodontal damage during both the progression and recovery stages of periodontitis. Although substantial evidence has demonstrated that incubation under an inflammatory condition may accelerate senescence of PDLSCs, whether cellular senescence in response to inflammatory incubation contributes to cell dysfunction remain unexplored. In this study, we first observed inflammation-caused PDLSC senescence in periodontitis based on comparisons of matched patients, and this cellular senescence was demonstrated in healthy cells that were subjected to inflammatory conditions. We subsequently designed further experiments to investigate the possible mechanism underlying inflammation-induced PDLSC senescence with a particular focus on the role of long noncoding RNAs (lncRNAs). LncRNA microarray analysis and functional gain/loss studies revealed SLC30A4-AS1 as a regulator of inflammation-mediated PDLSC senescence. By full-length transcriptome sequencing, we found that SLC30A4-AS1 interacted with SRSF3 to affect the alternative splicing (AS) of TP53BP1 and alter the expression of TP53BP1-204. Further functional studies showed that decreased expression of TP53BP1-204 reversed PDLSC senescence, and SLC30A4-AS1 overexpression-induced PDLSC senescence was abolished by TP53BP1-204 knockdown. Our data suggest for the first time that SLC30A4-AS1 plays a key role in regulating PDLSC senescence in inflammatory environments by modulating the AS of TP53BP1.

Neutrophil extracellular traps induced by diabetes aggravate periodontitis by inhibiting janus kinase/signal transducers and activators of transcription signaling in macrophages

Background/purpose

Diabetes, which is a systemic disease, increases susceptibility to destructive periodontal diseases, which are characterized by infectious susceptibility, but the potential mechanisms remain unknown. The aim of this study was to investigate the mechanism of high glucose environment promoting the occurrence and development of local periodontal inflammation.

Materials and methods

In this study, the effects of neutrophil extracellular traps (NETs) on macrophage polarization and the mechanism were designed to verify whether this course plays a role in periodontal tissue impairment associated with diabetes. Here, we examined the impact of NETs on macrophages in vitro. NETs were isolated from cultures of neutrophils exposed to hyperglycemia. Mouse models of diabetic periodontitis (DP) and macrophage polarization were developed, and the degrees of NET formation in the periodontal tissue of DP mice were assessed. Furthermore, western blotting was performed to analyze the related mechanisms.

Results

The results revealed that hyperglycemia induced the formation of NETs, and abundant NET formation led to proinflammatory cytokine secretion by macrophages and low expression of JAK-2 and STAT-3 in vitro and in vivo. NETs regulated macrophage polarization through the JAK/STAT pathway.

Conclusion

These results suggest that NETs target proinflammatory cytokine secretion via the JAK/STAT pathway and may play important roles in DP progression and macrophage polarization, which indicates that therapeutically referring to this regulatory pathway might be a promising method for treating diabetes-associated inflammatory diseases.

N6-methyladenosine-mediated overexpression of TREM-1 is associated with periodontal disease

Periodontitis, a prevalent inflammatory disease, involves the destruction of tooth-supporting tissues. N6-methyladenosine (m6A) is a type of post-transcriptional modification that significantly influences gene and protein expression. It is involved in the regulation of various diseases, including those with an inflammatory component. This study investigates the potential role of m6A-mediated TREM-1 expression in the development of periodontitis. Clinical features and TREM-1 expression were assessed in periodontitis patients and healthy controls. LPS-stimulated human gingival fibroblasts (HGFs) were used to investigate m6A levels, m6A regulator METTL3, TREM-1, and inflammatory gene expression. In silico functional analysis explored TREM-1 interactions and functionalities. Periodontitis patients showed significantly elevated TREM-1 expression at both mRNA and protein levels. Predicted m6A motifs were present within the TREM-1 transcript. LPS stimulation of HGFs increased m6A content, METTL3, and TREM-1 expression, suggesting a potential link between m6A modification and TREM-1 regulation. Bioinformatic analysis revealed TREM-1 interaction with genes associated with periodontitis and its association with inflammatory pathways. This study suggests a potential role for METTL3-mediated m6A modification in regulating TREM-1 expression in periodontitis. Further investigation is needed to solidify this link and translate findings into clinical applications for improved periodontal health.

The Role of Caspase-1 and Caspase-4 in Modulating Gingival Epithelial Cell Responses to Aggregatibacter actinomycetemcomitans Infection

Periodontitis is a chronic inflammatory disease characterized by bacterial infection and immune dysregulation. Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is a key pathogen linked to disease progression. Caspase-1 and caspase-4 regulate inflammasome activation and cytokine release, yet their roles in gingival epithelial immunity remain unclear. The aim of this study was to elucidate the involvement of caspase-1 and caspase-4 in regulating the immune response to A. actinomycetemcomitans infection in gingival epithelial cells. Human gingival epithelial cells (Ca9-22) and caspase-1- and caspase-4-deficient cells were infected with A. actinomycetemcomitans for 24 h. Inflammatory mediator release was analyzed using Olink proteomics. Bacterial colonization and invasion were assessed using fluorescence-based assays and gentamicin protection assays. Caspase-1- and caspase-4-deficient cells showed significantly altered cytokine and chemokine profiles after infection with A. actinomycetemcomitans, showing reduced IL-17C and IL-18 release. We also found an increased release of TGF-α and LIF from caspase-4-deficient cells, along with elevated levels of the chemokines IL-8, CXCL9, and CXCL10. Additionally, both caspase-1- and caspase-4-deficient cells showed increased bacterial colonization and invasion, particularly in caspase-4-deficient cells. These findings suggest that caspase-1 and caspase-4 play distinct yet essential roles in gingival epithelial immunity, regulating cytokine release, barrier integrity, and defense against A. actinomycetemcomitans colonization.

Anti-inflammatory and antimicrobial efficacy of coconut oil for periodontal pathogens: a triple-blind randomized clinical trial

OBJECTIVES

To evaluate the effect of coconut oil on the oral bacteriome and inflammatory response in patients with periodontitis by integrating next-generation sequencing analyses of pathogenic bacterial shifts and quantification of inflammatory markers, thereby assessing its potential as a natural adjunct to standard nonsurgical periodontal therapy.

MATERIALS AND METHODS

A triple-blind clinical trial was conducted with 30 participants diagnosed with periodontitis, randomized into 3 groups: (1) coconut oil, (2) chlorhexidine and (3) placebo. Saliva and gingival crevicular fluid (GCF) samples were collected before treatment, one month after treatment, and one month post-non-surgical periodontal therapy. Bacterial DNA was extracted, and the V3-V4 region of the 16 S rRNA gene was PCR-amplified and sequenced using Illumina MiSeq technologies. Inflammatory biomarkers, including Interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), were quantified from GCF samples.

RESULTS

Coconut oil treatment significantly reduced pathogenic bacterial families such as Spirochaetaceae and Tannerellaceae while promoting beneficial bacteria such as Streptococcaceae. At the genus and species levels, coconut oil reduced pathogens such as Tannerella forsythia and Treponema denticola along with increase in beneficial bacteria such as Streptococcus. The subgingival microbial dysbiosis index improved significantly in both coconut oil and chlorhexidine groups. Furthermore, the coconut oil demonstrated a reduction in IL-6 and TNF-α levels, indicating decreased local inflammation.

CONCLUSIONS

Coconut oil treatment significantly modulated the oral microbiome and reduced inflammatory markers in patients with periodontitis, suggesting its potential as a natural and effective adjunct in periodontal therapy.

CLINICAL RELEVANCE

This study highlights coconut oil's potential as a natural adjunct in periodontal therapy, effectively reducing pathogenic bacteria and inflammatory markers (IL-6, TNF-α). It offers a safe alternative to chlorhexidine, promoting microbiome balance and improved periodontal health.

Aptamers in dentistry: diagnosis, therapeutics, and future perspectives

Oral health is essential to general health. The diagnosis of dental diseases and treatment planning of dental care need to be straightforward and accurate. Recent studies have reported the use of aptamers in dentistry to achieve a simple diagnosis and facilitate therapy. Aptamers comprise nucleic acid sequences that possess a strong affinity for their target. Synthesized chemically, aptamers have several advantages, including smaller size, higher stability, and lower immunogenicity compared with monoclonal antibodies. They can be used to detect biomarkers in saliva and the presence of various pathogens, or can be used as a targeted drug delivery system for disease treatment. This review highlights current research on aptamers for dental care, especially the recent progress in oral disease diagnosis and therapeutics. The challenges and unresolved problems faced by the clinical use of aptamers are also discussed. In the future, the clinical applications of aptamers will be further extended to include, for example, dental indications and regenerative dentistry.

Minocycline-Loaded Titanium Dioxide Nanoparticles for Augmented Synergistic Periodontal Sonodynamic Chemotherapy

Background

The current clinical treatment of periodontitis usually involves mechanical removal of pathogenic bacteria through ultrasonic scaling and root planing, supplemented with antibacterial medications to inhibit microbial overgrowth. However, the therapeutic efficiency remains unsatisfactory due to complicated periodontal anatomy, limited plaque removal, short retention of antibiotics, and related side effects.

Methods and Results

To address these issues, we successfully synthesized mesoporous titanium dioxide nanoparticles (MTN) via a sol-gel method, which were modified with hemoglobin (Hb) and loaded with minocycline (MINO). The resulting Hb-MTN/MINO nanoparticles had a size of 215 nm, zeta potential of -19.8 mV±0.9 mV, and uniform shape with a PDI index of 0.176. The modification with hemoglobin (Hb) provided sufficient oxygen for antimicrobial sonodynamic therapy (aSDT), contributing to improved generation of reactive oxygen species (ROS) under low ultrasound intensity. After MINO loading, the system exhibited notable antibacterial efficacy, with a 6 log reduction of bacterial counts compared to the control group. Hb-MTN/MINO was evaluated in vivo in terms of oral index, soft and hard tissues, along with biosafety evaluation in periodontal disease model rats. Hb-MTN/MINO demonstrated a satisfactory therapeutic effect, whereby the periodontal condition of the rats exhibited a greater improvement than the control group, and measurement of the serum levels of inflammatory factors revealed that both IL-6 and MMP-9 were significantly downregulated.

Conclusion

These findings confirm the potential of Hb-MTN/MINO nanoparticles as a promising treatment option for periodontitis.

16S rRNA sequencing reveals relationships among enrichment of oral microbiota in the lower respiratory tract and pulmonary nodules malignant progression

Micro-aspiration of oral microorganisms results in considerable enrichment within the lower respiratory tract (LRT), constituting an early event in lung cancer pathogenesis. To explore the correlation between malignant risk of pulmonary nodules (PNs) and oral commensals enrichment in LRT, oral saliva and bronchial alveolar lavage fluid samples from 22 low-risk PN patients, 17 intermediate-risk PN patients, and 11 high-risk PN patients were analyzed using 16S rRNA gene sequencing. Alpha and beta diversity analyses reveal minimal variation in oral microbial diversity and abundance among patients with different risks of PN. In contrast, a significant reduction in the diversity of LRT microbiota is observed in patients at high risk of PN. Based on multigroup comparative analysis of species differences and the linear discriminant analysis effect size method, Synergistes and Tannerella were identified as the dominant bacterial genera in the oral and LRT of high-risk PN patients, respectively. The study found that the LRT microbiota of PN patients seemed to originate from the oral, and the high enrichment of oral microbiota in the lower respiratory tract was most common in high-risk PN patients. The predominant bacterial genera present in the oral cavity and LRT of patients with PN were identified through abundance variance analysis. Eight key microbial genera were found in both the oral cavity and LRT: Streptococcus, Granulicatella, Porphyromonas, Bacillus, Neisseria, Alloprevotella, Prevotella, and Leptotrichia. Notably, receiver operating characteristic analysis identified Streptococcus, Granulicatella, and Leptotrichia as reliable biomarkers to differentiate high-risk PN. Spearman correlation analysis confirmed that the accumulation of oral microorganisms in the LRT played an important role in the process of PN cancerization. The co-occurrence network showed that the coexistence of Veillonella and Streptococcus in the oral and LRT may be involved in the occurrence of PN, while the LRT cluster of Rothia occurred in high-risk PN patients. Correlation analysis among species identified microbial communities predominantly composed of Veillonella, which may facilitate pulmonary carcinogenesis.

IMPORTANCE

This study is the first to elucidate the composition and interrelationships of oral and lower respiratory tract (LRT) microbiota in patients with pulmonary nodule (PN) across varying malignancy risk levels. We conducted an analysis to investigate the correlation between the malignant potential of PNs and the enrichment of oral microbiota within the LRT. Additionally, we explored the feasibility of utilizing oral-lower respiratory commensal microbiota as biomarkers to assess the benign and malignant nature of pulmonary nodules. This study aims to provide evidence supporting early diagnosis and intervention strategies for lung cancer.

Plant and animal-derived fusion nanovesicles rescue inflammation-compromised osteogenic potential of periodontal ligament stem cells

Periodontitis is a chronic inflammatory disease affecting the supporting tissues of the teeth and has emerged as a global public health issue. Current therapies primarily address pathogenic factors and alleviate symptoms, with limited options available for complete restoration and reconstruction of already absorbed periodontal bone tissue. In this study, we developed a nanotherapeutic strategy utilizing fusion nanovesicles (FVs) to modulate the inflammatory microenvironment and create a regenerative niche for periodontal ligament stem cells (PDLSCs), which play a crucial role in periodontal tissue repair. The FVs are composed of Scutellaria baicalensis nanovesicles (SBNVs) with anti-Porphyromonas gingivalis (P. gingivalis) and anti-inflammatory properties, combined with PDLSC membrane-derived nanovesicles genetically engineered to express TNFR1. These FVs preserved the biological activity of SBNVs and the immunomodulatory function of PDLSCs. Additionally, FVs effectively captured and cleared TNF-α from the microenvironment through TNFR1. Moreover, FVs alleviated the inflammatory response of PDLSCs induced by P. gingivalis-LPS (Pg-LPS) and TNF-α, restoring their proliferation, migration, and osteogenic differentiation capabilities. Hence, this nanotherapeutic strategy holds great potential for treating periodontitis.

Microbiological and Metabolomic Analysis of Biomarkers for Grades A and B in Stage II Periodontitis

Periodontitis is a chronic inflammatory disease characterized by inflammation of the periodontal soft tissues and loss of alveolar bone. In the oral environment, subgingival microorganisms and salivary metabolites reflect the host's health status. This study aimed to understand periodontitis severity and progression rate by analyzing subgingival microflora and salivary metabolites to identify potential biomarkers. Fifty-three volunteers with stage II periodontitis were graded using the bone loss (%)/age index into two grades: 33 in grade A (< 0.25) and 20 in grade B (0.25-1.00). Using a case-control study, simultaneously analyzed biomarkers associated with the severity and rate of progression of periodontitis. The red complex, the orange complex, Campylobacter spp., uncultured Candidatus Saccharibacteria and metabolites such as 5-Aminovaleric acid, N1-Acetylspermine showed a significant positive correlation with periodontal clinical parameters. Furthermore, we identified four of the salivary differential metabolites (DL-Leucineamide, Dodecanedioic acid, L-Tyrosine methyl ester and Phenylpyruvic acid) that may serve as potential biomarkers for predicting the rate of periodontitis progression. These results showed that the red complex significantly correlated with periodontitis severity and influenced changes in salivary metabolites. Additionally, biomarkers indicating the progression rate were predominantly amino acid derivatives, confirming that interactions between microorganisms and metabolites may exacerbate periodontitis development.

Advances in modeling periodontal host-microbe interactions: insights from organotypic and organ-on-chip systems

Periodontal disease, a chronic inflammatory condition affecting the supporting structures of teeth, is driven by an imbalanced interaction between the periodontal microbiota and the host inflammatory response. Beyond its local impact, periodontal disease is associated with systemic conditions such as diabetes mellitus, cardiovascular disease, and inflammatory bowel disease, emphasizing the importance of understanding its mechanisms. Traditional pre-clinical models, such as monolayer cultures and animal studies, have provided foundational insights but are limited by their physiological relevance and ethical concerns. Recent advancements in tissue engineering and microfluidic technologies have led to the development of three-dimensional (3D) organotypic culture models and organ-on-chip systems that more closely mimic native tissue microenvironments. This review provides an overview of the evolution of methods to study periodontal host-microbe interactions, from simple 2D monolayer cultures to complex 3D organotypic and microfluidic organ-on-chip (OoC) models. We discuss various fabrication strategies, host-microbe co-culture techniques, and methods for evaluating outcomes in these advanced models. Additionally, we highlight insights gained from gut-on-chip platforms and their potential applications in periodontal research and understanding oral-systemic links of periodontal disease. Through a comprehensive overview of current advancements and future directions, this review provides insights on the transformative potential of OoC technology in periodontal research, offering new avenues for studying disease mechanisms and developing therapeutic strategies.

Immunological landscape of periodontitis and rheumatoid arthritis and their molecular crosstalk

BACKGROUND

The association between periodontitis (PT) and rheumatoid arthritis (RA) is well-established; however, the molecular mechanisms underlying this relationship remain poorly understood. This study aims to delineate shared genetic and molecular features between PT and RA to uncover potential common pathways involved in their pathogenesis.

METHODS

Gene expression data sets for PT and RA were retrieved from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) and co-expressed gene modules were identified using weighted gene co-expression network analysis (WGCNA) and the DESeq2 package. Enrichment analyses, including KEGG and Gene Ontology (GO) pathways, as well as immune cell infiltration profiling, were performed to explore shared biological pathways. A protein-protein interaction (PPI) network was constructed to pinpoint key genes linking PT and RA. Functional assays were conducted by overexpressing the identified core gene, PTPRC, in MH7A cells via lentiviral transfection, followed by cell viability (CCK-8), migration, and invasion assays. In addition, transcription factor enrichment and connectivity map (cMAP) analyses were employed to identify common transcriptional regulators and potential therapeutic targets for both conditions.

RESULTS

WGCNA and DESeq2 analyses revealed 154 shared DEGs between PT and RA, predominantly enriched in immune and inflammatory response pathways. PTPRC emerged as a pivotal shared gene, exhibiting significantly higher expression in PT patients compared to controls. In vitro assays confirmed that PTPRC overexpression enhanced fibroblast proliferation, migration, and invasion. Furthermore, transcription factor enrichment analysis and cMAP identified overlapping transcriptional regulators and potential pharmacological agents for both diseases.

CONCLUSIONS

This study provides novel insights into shared gene expression profiles and molecular mechanisms linking PT and RA, identifying PTPRC as a potential key regulator. These findings suggest that targeting PTPRC could offer therapeutic opportunities for RA driven by PT.

The Oral Microbiome and Systemic Health: Bridging the Gap Between Dentistry and Medicine

The oral microbiome, consisting of a mixture of bacteria, fungi, and viruses, is an important contributor to oral and systemic health. Microbial balance disruptions are associated with oral pathologies like dental caries and periodontitis as well as systemic diseases such as cardiovascular diseases, adverse pregnancy outcomes, and respiratory diseases. This review explores the mechanistic pathways linking oral dysbiosis to systemic inflammation, endothelial dysfunction, and immune modulation. The roles of key microbial species in health and disease are analyzed, with an emphasis on how hematogenous dissemination leads to systemic pathologies through inflammatory signaling. Also, advances in high throughput sequencing are discussed, as well as microbial diversity and its implications for diagnostics and therapeutics. The review highlights the potential of oral microbiota-targeted interventions to mitigate systemic diseases through dentistry and medicine integration, by throwing light on interdisciplinary strategies. Future work should focus on the evaluation of the mechanisms by which the oral microbiome plays a role in systemic diseases through the integration of multi-omics approaches such as metagenomics, transcriptomics, and metabolomics. Furthermore, clinical trials need to be designed in a way to evaluate the efficacy of microbiome-targeted therapies in the prevention of cardiovascular diseases, adverse pregnancy outcomes, and autoimmune disorders.

Mesenchymal stem cell-derived protein extract induces periodontal regeneration

BACKGROUND

Periodontal disease is characterized by chronic inflammation and destruction of supporting periodontal tissues, ultimately leading to tooth loss. In recent years, "cell-free treatment" without stem cell transplantation has attracted considerable attention for tissue regeneration. This study investigated the effects of extracts of mesenchymal stem cells (MSC-extract) and their protein components (MSC-protein) on the proliferation and migration of periodontal ligament (PDL) cells and whether MSC-protein can induce periodontal regeneration.

METHODS

MSC-extract and MSC-protein were obtained by subjecting mesenchymal stem cells (MSCs) to freeze-thaw cycles and acetone precipitation. Cell proliferation was examined using a WST-8 assay and Ki67 immunostaining, and cell migration was examined using Boyden chambers. The MSC-protein content was analyzed using liquid chromatography-mass spectrometry, protein arrays, and enzyme-linked immunosorbent assays (ELISAs). Gene expression in MSC-protein-treated PDL cells was examined using RNA-sequencing and Gene Ontology analyses. The regenerative potential of MSC-protein was examined using micro-computer tomography (CT) and histological analyses after transplantation into a rat periodontal defect model.

RESULTS

MSC-extract and MSC-protein promoted the proliferation and migration of PDL cells. Protein array and ELISA revealed that MSC-protein contained high concentrations of basic fibroblast growth factor (bFGF) and hepatocyte growth factor (HGF). Exogenous bFGF promoted the proliferation and migration of PDL cells. Furthermore, the transplantation of MSC-protein enhanced periodontal tissue regeneration with the formation of new alveolar bone and PDLs.

CONCLUSIONS

These results indicate that the MSC-protein promotes the proliferation and migration of PDL cells and induces significant periodontal tissue regeneration, suggesting that the MSC-protein could be used as a new cell-free treatment for periodontal disease.

Chairside live biotherapeutic hydrogel for comprehensive periodontitis therapy

Periodontitis, characterized by microbial dysbiosis and immune dysregulation, destroys tooth-supporting tissues and negatively affects overall health. Current strategies face significant challenges in restoring damaged tissues while halting periodontitis progression. In this study, we introduce a live biotherapeutic product (LBP) in an engineered living hydrogel for comprehensive periodontitis therapy. A dental blue light-responsive hydrogel (LRG) was fabricated to deliver and confine live Lactobacillus rhamnosus GG (LGG) in periodontal pockets, endowing the LRG with sustained antibacterial and immunomodulatory effects. The LRG was engineered through peptide modification to also promote tissue regeneration. Both in vitro and in vivo evaluations confirmed the effectiveness of this integrated therapeutic strategy, which combines antibacterial, anti-inflammatory, and regenerative properties with an underlying immunomodulatory mechanism that involves suppressor of cytokine signaling (SOCS)3 upregulation and the Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway suppression in macrophages. Demonstrating a new paradigm, this proof of concept highlights the synergistic integration of live organisms and synthetic material engineering in a chairside treatment to address the multifaceted etiology of periodontitis.

Evaluation of Salivary Il-38 Levels in Periodontitis: A Cross-Sectional Study

The goal of the current study was to assess levels of salivary interleukin (IL)-38, IL-1β, and IL-10 in various periodontal clinical conditions. In total, 60 (20 healthy, 20 gingivitis, and 20 stage II-III, grade A-B periodontitis) subjects were included in the study. Demographic and clinical periodontal parameters were recorded. Samples were examined for IL-38, IL-1β, and IL-10 levels by means of enzyme-linked immunosorbent assay. Results demonstrated that the periodontitis group had significantly lower salivary IL-38 levels (P < 0.05) than the healthy group. Salivary IL-10 levels did not differ significantly between the groups (P > 0.05). The salivary IL-1β levels of gingivitis (P < 0.001) and periodontitis groups (P < 0.01) were significantly higher than those of the healthy group. The present study indicated that IL-38 level is decreased in periodontal disease. The results suggested a possible role of IL-38 in the periodontal inflammation process. Clarifying the mechanisms of IL-38 in the inflammatory process may contribute to the development of novel treatment strategies in periodontal diseases.

Topology and functional characterization of major outer membrane proteins of Treponema maltophilum and Treponema lecithinolyticum

Numerous Treponema species are prevalent in the dysbiotic subgingival microbial community during periodontitis. The major outer sheath protein is a highly expressed virulence factor of the well-characterized species Treponema denticola. Msp forms an oligomeric membrane protein complex with adhesin and porin properties and contributes to host-microbial interaction. Treponema maltophilum and Treponema lecithinolyticum species are also prominent during periodontitis but are relatively understudied. Msp-like membrane surface proteins exist in T. maltophilum (MspA) and T. lecithinolyticum (MspTL), but limited information exists regarding their structural features or functionality. Protein profiling reveals numerous differences between these species, but minimal differences between strains of the same species. Using protein modeling tools, we predict MspA and MspTL monomeric forms to be large β-barrel structures composed of 20 all-next-neighbor antiparallel β strands which most likely adopt a homotrimer formation. Using cell fractionation, Triton X-114 phase partitioning, heat modifiability, and chemical and detergent release assays, we found evidence of amphiphilic integral membrane-associated oligomerization for both native MspA and MspTL in intact spirochetes. Proteinase K accessibility and immunofluorescence assays demonstrate surface exposure of MspA and MspTL. Functionally, purified recombinant MspA or MspTL monomer proteins can impair neutrophil chemotaxis. Expressions of MspA or MspTL with a PelB leader sequence in Escherichia coli also demonstrate surface exposure and can impair neutrophil chemotaxis in an in vivo air pouch model of inflammation. Collectively, our data demonstrate that MspA and MspTL membrane proteins can contribute to pathogenesis of these understudied oral spirochete species.

Biofabrication - Revolutionizing the future of regenerative periodontics

Periodontium is a compartmentalized and highly specialized tissue responsible for tooth stability. Loss of tooth attachment due to periodontitis and trauma is a complex clinical burden affecting a large parcel of the adult and elderly population worldwide, and regenerative strategies to reestablish the native conditions of the periodontium are paramount. Biofabrication of scaffolds, through various techniques and materials, for regenerative periodontics has significantly evolved in the last decades. From the basics of occlusive membranes and graft materials to the complexity of converging 3D printing and Bioprinting using image-based models, biofabrication opens many possibilities for patient-specific scaffolds that recapitulate the anatomical and physiological conditions of periodontal tissues and interfaces. Thus, this review presents fundamental concepts related to the native characteristics of the periodontal tissues, the key to designing personalized strategies, and the latest trends of biofabrication in regenerative periodontics with a critical overview of how these emerging technologies have the potential to shift the one-size-fits-all paradigm.

Adjunctive Treatment Effect of Non-Thermal Atmospheric Pressure Plasma in Periodontitis-Induced Rats

Background/Objectives: As non-thermal atmospheric pressure plasma (NTP) is known to have advantages in application in the medical field, we consider its applicability to periodontitis, a representative chronic inflammatory disease. The purpose of this study was to evaluate the effect of NTP in inhibiting the progression of periodontitis in a rat model when additionally used in scaling and root planing (SRP). Methods: To induce experimental periodontitis in 20 rats, ligatures were placed in the maxillary second molar and lipopolysaccharide from Porphyromonas gingivalis was injected around the teeth. Then, NTP treatment was performed for 2 or 5 min, together with scaling and root planing (SRP). To evaluate alveolar bone loss, micro-computed tomography (micro-CT) analysis and hematoxylin-eosin (H-E) staining were performed. Tartrate-resistant acid phosphatase (TRAP) analysis was performed to compare the number of osteoclasts, while immunohistochemistry (IHC) analysis was performed to determine the expression levels of receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG). Enzyme-linked immunosorbent assay (ELISA) analysis was performed for the detection of cytokines (TNF-α, IL-1β, and IL-10) in tissues and sera. Results: When SRP was combined with NTP, alveolar bone loss was decreased, the number of osteoclasts and RANKL expression were decreased, OPG expression was increased, and pro-inflammatory cytokine (TNF-α and IL-1β) levels were significantly decreased. Compared with the NTP treatment for 2 min, when treated for 5 min, less alveolar bone loss, fewer osteoclasts, a lower RANKL expression level, and a higher OPG expression level were observed. Conclusions: This study evaluated the adjunctive treatment effect of NTP in periodontitis-induced rats. Based on the results of this study, we suggest that supplemental NTP treatment may be a good option for non-surgical periodontal treatment; however, further studies are needed to elucidate the mechanism through which NTP suppresses periodontal inflammation.

Hotspots and global trends in research of host immune response in periodontitis: A bibliometric analysis

BACKGROUND

The host immune response plays a major role in the pathogenesis of periodontitis. A bibliometric study can be crucial to understanding the different processes involved in this area; however, to our knowledge, it has not been published until now. Therefore, a bibliometric analysis was conducted to assess research hotspots and global trends in scientific articles about the immune response in periodontitis published between 1952 and 2023.

METHODS

The search strategy was defined using keywords and Boolean operators. The Web of Science Core Collection database was used. In addition, the bibliometric analysis was performed using four tools: Python 3.12, VOSviewer 1.6.19, R-Bibliometrix, and CiteSpace.

RESULTS

A total of 7696 articles were included, comprising 6691 regular articles and 1005 review articles. Data analysis revealed an increasing trend in the number of publications over the years in this field, with the most cited article written by Preshaw et al. (2012). Leading countries in article production include the United States, China, Japan, and Brazil. Regarding institutions, the University of Helsinki had the highest number of publications (N = 339), with one of its researchers being the author with the most publications (Dr. Sorsa, N = 143, H-index = 52). Concerning journals, the Journal of Periodontology was the most influential journal. Finally, recent trending topics in research were related to the influence of inflammation on dysbiosis, immune biomarkers, immunomodulation, and the impact of aging on immunocompetence.

CONCLUSION

This bibliometric study demonstrated a growing interest and the emergence of new trends in research on host immune response in periodontitis.

Prevalence of the oral pathogen Filifactor alocis and its FtxA toxin related to clinical parameters and presence of Aggregatibacter actinomycetemcomitans

The Gram-positive organism Filifactor alocis is implicated in multiple oral diseases including periodontitis, and approximately 50% of known strains encode and produce a recently identified repeat-in-toxin (RTX) protein, FtxA, partly homologous to the Aggregatibacter actinomycetemcomitans leukotoxin. By assessing a longitudinal Ghanaian study population of adolescents, we recently identified a possible correlation between F. alocis levels, ftxA gene carriage, and progression of clinical attachment loss (CAL). To extend knowledge on the possible significance of F. alocis and its FtxA in periodontal disease, we have in the present work analyzed saliva samples in an independent cohort of periodontitis (n=156), collected at two private periodontal specialist practices in Perth, Western Australia. The present results corroborate that high loads of F. alocis and the presence of its ftxA gene together are associated with parameters of periodontal tissue destruction and severity. Moreover, among the individuals carrying A. actinomycetemcomitans, a majority also exhibited an ftxA-positive F. alocis, supporting the notion of the synergistic behavior of these two species. This emphasizes that F. alocis and its ftxA are involved in the pathogenesis of periodontitis and may have ecological roles, with diagnostic and prognostic implications for the disease.

Alzheimer's Disease and Porphyromonas gingivalis: Exploring the Links

Recent research highlights compelling links between oral health, particularly periodontitis, and systemic diseases, including Alzheimer's disease (AD). Although the biological mechanisms underlying these associations remain unclear, the role of periodontal pathogens, particularly Porphyromonas gingivalis, has garnered significant attention. P. gingivalis, a major driver of periodontitis, is recognized for its potential systemic effects and its putative role in AD pathogenesis. This review examines evidence connecting P. gingivalis to hallmark AD features, such as amyloid β accumulation, tau hyperphosphorylation, neuroinflammation, and other neuropathological features consistent with AD. Virulence factors, such as gingipains and lipopolysaccharides, were shown to be implicated in blood-brain barrier disruption, neuroinflammation, and neuronal damage. P. gingivalis-derived outer membrane vesicles may serve to disseminate virulence factors to brain tissues. Indirect mechanisms, including systemic inflammation triggered by chronic periodontal infections, are also supposed to exacerbate neurodegenerative processes. While the exact pathways remain uncertain, studies detecting P. gingivalis virulence factors and its other components in AD-affected brains support their possible role in disease pathogenesis. This review underscores the need for further investigation into P. gingivalis-mediated mechanisms and their interplay with host responses. Understanding these interactions could provide critical insights into novel strategies for reducing AD risk through periodontal disease management.

Synthetic Vesicle-Based Drug Delivery Systems for Oral Disease Therapy: Current Applications and Future Directions

Oral diseases such as dental caries, periodontitis, and oral cancer are prevalent and present significant challenges to global public health. Although these diseases are typically treated through procedures like dental preparation and resin filling, scaling and root planning, or surgical excision, these interventions are often not entirely effective, and postoperative drug therapy is usually required. Traditional drug treatments, however, are limited by factors such as poor drug penetration, significant side effects, and the development of drug resistance. As a result, there is a growing need for novel drug delivery systems that can enhance therapeutic efficacy, reduce side effects, and improve treatment outcomes. In recent years, drug-loaded vesicles, such as liposomes, polymersomes, and extracellular vesicles (EVs), have emerged as promising drug delivery platforms due to their high drug encapsulation efficiency, controlled release properties, and excellent biocompatibility. This review provides an in-depth examination of the characteristics, advantages, and limitations of liposomes, polymersomes, and extracellular vesicles in the context of oral disease treatment. It further explores the reasons for their advantages and limitations and discusses the specific applications, development prospects, and strategies for optimizing these vesicle-based systems for improved clinical outcomes.

Impact of Periodontitis and Oral Dysbiosis Metabolites in the Modulation of Accelerating Ageing and Human Senescence

Periodontitis, a chronic multifactorial inflammatory condition of the periodontium, is originated by a dysbiotic oral microbiota and is negatively correlated with several systemic diseases. The low-chronic burden of gingival inflammation not only exacerbates periodontitis but also predisposes individuals to a spectrum of age-related conditions, including cardiovascular diseases, neurodegenerative disorders, and metabolic dysfunction, especially related to ageing. In this regard, over the local periodontal treatment, lifestyle modifications and adjunctive therapies may offer synergistic benefits in ameliorating both oral and systemic health in ageing populations. Elucidating the intricate connections between periodontitis and senescence is important for understanding oral health's systemic implications for ageing and age-related diseases. Effective management strategies targeting the oral microbiota and senescent pathways may offer novel avenues for promoting healthy ageing and preventing age-related morbidities. This review will analyze the current literature about the intricate interplay between periodontitis, oral dysbiosis, and the processes of senescence, shedding light on their collective impact on the modulation and accelerated ageing and age-related diseases. Lastly, therapeutic strategies targeting periodontitis and oral dysbiosis to mitigate senescence and its associated morbidities will be discussed.

Microfluidic organ-on-chip systems for periodontal research: advances and future directions

Advances in tissue engineering and microfluidic technologies have enabled the development of sophisticated in vitro models known as organ-on-a-chip (OoC) or microphysiological systems. These systems enable to potential to simulate the dynamic interactions between host tissues and their microenvironment including microbes, biomaterials, mechanical forces, pharmaceutical, and consumer-care products. These fluidic technologies are increasingly being utilized to investigate host-microbe and host-material interactions in oral health and disease. Of interest is their application in understanding periodontal disease, a chronic inflammatory condition marked by the progressive destruction of periodontal tissues, including gingiva, periodontal ligament, and alveolar bone. The pathogenesis of periodontal disease involves a complex interplay between microbial dysbiosis and host immune responses, which can lead to a loss of dental support structures and contribute to systemic conditions such as cardiovascular disease, diabetes, and inflammatory bowel disease. This provides a comprehensive overview of the latest developments in millifluidic and microfluidic systems designed to emulate periodontal host-microbe and host-material interactions. We discuss the critical engineering and biological considerations in designing these platforms, their applications in studying oral biofilms, periodontal tissue responses, and their potential to unravel disease mechanisms and therapeutic targets in periodontal disease.

A Multifunctional Cobalt-Containing Implant for Treating Biofilm Infections and Promoting Osteointegration in Infected Bone Defects Through Macrophage-Mediated Immunomodulation

Treating bone infections and ensuring bone recovery is one of the major global problems facing modern orthopedics. Prolonged antibiotic use may increase the risk of antimicrobial resistance, and inflammation caused by biofilms can obstruct tissue healing, making bone infection treatment even more challenging. The optimal treatment strategy combines immune response modification to promote osteogenesis with effective bacterial infection removal that does not require long-term antibiotic use. A one-step plasma immersion ion implantation approach is used to create titanium alloy implants incorporating cobalt. According to experimental findings, cobalt-containing titanium implants exhibit improved antibacterial activity by efficiently disrupting biofilm formations and reducing Methicillin-resistant Staphylococcus aureus adherence by over 80%. Additionally, the implants exhibit superior anti-inflammatory and osseointegration properties. RNA sequencing analysis reveals the potential mechanism of Co2+ in regulating the polarization of macrophages toward the anti-inflammatory M2 phenotype, which is crucial for creating an immune environment conducive to bone healing. Concurrently, these implants promote osteogenic differentiation while suppressing osteoclast activity, further supporting bone repair. Overall, without exogenous recombinant proteins or antibiotics, the implants effectively eradicate infections and expedite bone repair, offering a novel therapeutic strategy for complex skeletal diseases with clinical promise.

Navigating a complex dance: the interplay between RNA-binding proteins and T cells in oral epithelial plasticity

The oral epithelium, a dynamic interface constantly facing environmental challenges, relies on intricate molecular pathways to maintain its homeostasis. This comprehensive review delves into the nuanced interplay between T-lymphocytic cells (T cells) and RNA-binding proteins (RBPs) within the oral epithelium, elucidating their roles in orchestrating immune responses and influencing tissue plasticity. By synthesizing current knowledge, we aim to unravel the molecular intricacies that govern this interplay, with a focus on potential therapeutic implications for oral health and diseases. Understanding the regulatory networks shaped by T cells and RBPs in the oral epithelial microenvironment holds promise for innovative strategies in managing conditions associated with epithelial dysfunction.