Roles of Porphyromonas gingivalis and its virulence factors in periodontitis

Oral inoculation of Fusobacterium nucleatum exacerbates ulcerative colitis via the secretion of virulence adhesin FadA

Fusobacterium nucleatum (F. nucleatum), an anaerobic resident of the oral cavity, is increasingly recognized as a contributing factor to ulcerative colitis (UC). The adhesive properties of F. nucleatum are mediated by its key virulence protein, FadA adhesin. However, further investigations are needed to understand the pathogenic mechanisms of this oral pathogen in UC. The present study aimed to explore the role of the FadA adhesin in the colonization and invasion of oral F. nucleatum in dextran sulphate sodium (DSS)-induced colitis mice via molecular techniques. In this study, we found that oral inoculation of F. nucleatum strain carrying the FadA adhesin further exacerbated DSS-induced colitis, leading to elevated alveolar bone loss, disease severity, and mortality. Additionally, CDH1 gene knockout mice treated with DSS presented increases in body weight and alveolar bone density, as well as a reduction in disease severity. Furthermore, FadA adhesin adhered to its mucosal receptor E-cadherin, leading to the phosphorylation of β-catenin and the degradation of IκBα, the activation of the NF-κB signalling pathway and the upregulation of downstream cytokines. In conclusion, this research revealed that oral inoculation with F. nucleatum facilitates experimental colitis via the secretion of the virulence adhesin FadA. Targeting the oral pathogen F. nucleatum and its virulence factor FadA may represent a promising therapeutic approach for a portion of UC patients.

Glycolanguage of the oral microbiota

The oral cavity harbors a diverse and dynamic bacterial biofilm community which is pivotal to oral health maintenance and, if turning dysbiotic, can contribute to various diseases. Glycans as unsurpassed carriers of biological information are participating in underlying processes that shape oral health and disease. Bacterial glycoinfrastructure-encompassing compounds as diverse as glycoproteins, lipopolysaccharides (LPSs), cell wall glycopolymers, and exopolysaccharides-is well known to influence bacterial fitness, with direct effects on bacterial physiology, immunogenicity, lifestyle, and interaction and colonization capabilities. Thus, understanding oral bacterias' glycoinfrastructure and encoded glycolanguage is key to elucidating their pathogenicity mechanisms and developing targeted strategies for therapeutic intervention. Driven by their known immunological role, most research in oral glycobiology has been directed onto LPSs, whereas, recently, glycoproteins have been gaining increased interest. This review draws a multifaceted picture of the glycolanguage, with a focus on glycoproteins, manifested in prominent oral bacteria, such as streptococci, Porphyromonas gingivalis, Tannerella forsythia, and Fusobacterium nucleatum. We first define the characteristics of the different glycoconjugate classes and then summarize the current status of knowledge of the structural diversity of glycoconjugates produced by oral bacteria, describe governing biosynthetic pathways, and list biological roles of these energetically costly compounds. Additionally, we highlight emerging research on the unraveling impact of oral glycoinfrastructure on dental caries, periodontitis, and systemic conditions. By integrating current knowledge and identifying knowledge gaps, this review underscores the importance of studying the glycolanguage oral bacteria speak to advance our understanding of oral microbiology and develop novel antimicrobials.

Inflammation indices in association with periodontitis and cancer

Inflammation is a complex physiological process that plays a pivotal role in many if not all pathological conditions, including infectious as well as inflammatory diseases, like periodontitis and autoimmune disorders. Inflammatory response to periodontal biofilms and tissue destruction in periodontitis is associated with the release of inflammatory mediators. Chronic inflammation can promote the development of cancer. Persistence of inflammatory mediators plays a crucial role in this process. Quantification and monitoring of the severity of inflammation in relation to cancer is essential. Periodontitis is mainly quantified based on the severity and extent of attachment loss and/or pocket probing depth, in addition with bleeding on probing. In recent years, studies started to investigate inflammation indices in association with periodontal diseases. To date, only few reviews have been published focusing on the relationship between blood cell count, inflammation indices, and periodontitis. This review presents a comprehensive overview of different systemic inflammation indices, their methods of measurement, and the clinical applications in relation to periodontitis and cancer. This review outlines the physiological basis of inflammation and the underlying cellular and molecular mechanisms of the parameters described. Key inflammation indices are commonly utilized in periodontology such as the neutrophil to lymphocyte ratio. Inflammation indices like the platelet to lymphocyte ratio, platelet distribution width, plateletcrit, red blood cell distribution width, lymphocyte to monocyte ratio, delta neutrophil index, and the systemic immune inflammation index are also used in hospital settings and will be discussed. The clinical roles and limitations, relationship to systemic diseases as well as their association to periodontitis and treatment response are described.

m6Am Methyltransferase PCIF1 Regulates Periodontal Inflammation

N6,2'-O-dimethyladenosine (m6Am), a common mRNA modification in eukaryotic capped mRNAs, plays a pivotal role in cellular functions and disease progression. However, its involvement in host inflammation remains elusive. Here, we demonstrate that loss of m6Am methyltransferase phosphorylated CTD interacting factor 1 (PCIF1) attenuates periodontal inflammation in whole-body and myeloid lineage-specific knockout mouse models. Pcif1 deletion inhibits macrophage phagocytosis and migration through m6Am-Csf1r signaling. In addition, colony-stimulating factor-1 receptor (CSF1R) is identified as a potential target for the treatment of periodontitis. We thus reveal a previously unrecognized role for PCIF1-mediated m6Am modification in governing macrophage responses and periodontal inflammation.

Photodynamic therapy on mRNA levels in bacteria

Antimicrobial photodynamic therapy (aPDT) has shown efficacy in inactivating different bacterial species by photosensitizer-induced free radical production. Despite aPDT is considered unable to cause resistant strains, enzymatic pathways for detoxification of reactive oxygen species and transmembrane photosensitizer efflux systems could cause resistance to aPDT. Resistance mechanisms can be evaluated by measurement of mRNA from by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Thus, the aim of this study was to access the mRNA level data obtained by RT-qPCR in bacterial cells submitted to photodynamic therapy. Studies performed on mRNA levels in bacteria after PDT were assessed on MEDLINE/Pubmed. The mRNA levels from genes related to various functions have been successfully evaluated in both Gram-positive and -negative bacteria after aPDT by RT-qPCR. Such an approach has improved the understanding of aPDT-induced effects, and reinforced the effectiveness of aPDT on bacteria, which can cause infections in different human tissues.

Anti-inflammatory effects of hesperidin on human gingival fibroblasts stimulated by lipopolysaccharide of Porphyromonas gingivalis in vitro

Periodontal disease is an inflammatory disease caused by periodontopathogenic bacteria, the inflammatory response generated against them, and host factors. Furthermore, environmental factors can lead to disease progression. Using lipopolysaccharide (LPS)-stimulated human gingival fibroblast (HGF), this study investigated the bioactivity of HGF after exposure to hesperidin (Hesp) and the anti-inflammatory activity of Hesp against early periodontitis. HGF were cultured in Dulbecco's modified Eagle's medium containing 15% fetal bovine serum. They were exposed to LPS for 6 h, followed by Hesp (1, 10, 30, and 50 µM) exposure for 4 h. Cell proliferation was evaluated using reduction staining with alamerBlue™. Inflammatory cytokines [interleukin (IL)-6 and IL-8] and Toll-like receptor 4 (TLR4) levels were assessed using reverse transcription quantitative polymerase chain reaction. Hesp 50 µM + LPS inhibited cell proliferation. The Hesp exposure group inhibited the expression of IL-8 and IL-6. No significant difference in TLR4 expression was observed. Hesp significantly suppressed IL-6 and IL-8 expression by inhibiting downstream signaling without inhibiting TLR4 activation.

A Novel Therapeutic Calcium Peroxide Loaded Injectable Bio-adhesive Hydrogel Against Periodontitis

OBJECTIVES

Periodontitis is a prevalent oral disease that can significantly impact patients' life quality and systemic health. However, non-surgical subgingival scaling is largely compromised due to poor patient compliance, leading to a high recurrence rate of periodontitis. Therefore, this research aims to explore new approaches to enhance the effectiveness of existing local drug administration therapies.

MATERIALS AND METHODS

Gelatin-oxidized dextran hydrogel loaded with calcium peroxide and penicillin (CP-P hydrogel) was synthesized and characterized using Universal mechanical testing machine, Fourier transform infrared spectroscopy, swelling test, and dissolved oxygen meter. Furthermore, the cytotoxicity, osteogenic ability, antibacterial behavior, and alveolar bone regenerating capability of CP-P hydrogel were conducted both in vitro and in vivo.

RESULTS

The CP-P hydrogel demonstrated excellent mechanical properties, minimal swelling, and ideal biocompatibility. It created more favorable environments in the periodontal pocket by reversing anaerobic environment, eliminating drug-resistant bacteria and enhancing the therapeutic potency of drugs. By continuously releasing drugs in the periodontal pocket, the CP-P hydrogel effectively inhibited bacteria and reduce local inflammation response. In addition to bacteriostatic effects, the CP-P hydrogel also promoted the expression of osteogenic genes and enhanced osteogenic differentiation of PDLSCs in vitro.

CONCLUSIONS

CP-P hydrogel can be developed as a new therapeutic platform to enhance the effectiveness of local drug administration strategy against periodontitis.

Exploring oral bacterial compositional network in two oral disease groups using a convergent approach of NGS-molecular diagnostics

BACKGROUND

Since most of the commonly known oral diseases are explained in link with balance of microbial community, an accurate bacterial taxonomy profiling for determining bacterial compositional network is essential. However, compared to intestinal microbiome, research data pool related to oral microbiome is small, and general 16S rRNA screening method has a taxonomy misclassification issue in confirming complex bacterial composition at the species level.

OBJECTIVE

Present study aimed to explore bacterial compositional networks at the species level within saliva of 39 oral disease patients (Dental Caries group: n = 26 and Periodontitis group: n = 13) through comparison with public Korean-specific healthy oral microbiome data.

METHODS

Here, we applied comprehensive molecular diagnostics based on qRT-PCR and Sanger sequencing methods to complement the technical limitations of NGS-based 16S V3-V4 amplicon sequencing technology.

RESULTS

As a result of microbiome profiling at the genus level, relative frequencies of many nitrate-reducing bacteria within each oral disease group were found to be significantly low compared to the healthy group. In addition, the molecular diagnostics-based bacterial identification method allowed the determination of the correct taxonomy of screened primary colonizers (Streptococcus and Actinomyces unclassification clusters) for each oral disease. Finally, as with the results of microbiome profiling at the genus level, many core-species classified within the saliva of each oral disease group were also related to nitrate-reduction, and it was estimated that various pathogens associated with each disease formed a bacterial network with the core-species.

CONCLUSION

Our study introduced a novel approach that can compensate for the difficulty of identifying an accurate bacterial compositional network at the species level due to unclear taxonomy classification by using the convergent approach of NGS-molecular diagnostics. Ultimately, we suggest that our experimental approach and results could be potential reference materials for researchers who intend to prevent oral disease by determining the correlation between oral health and bacterial compositional network according to the changes in the relative frequency for nitrate-reducing species.

Capsaicin attenuates Porphyromonas gingivalis-suppressed osteogenesis of periodontal ligament stem cells via regulating mitochondrial function and activating PI3K/AKT/mTOR pathway

BACKGROUND AND OBJECTIVE

Prevention of periodontal bone resorption triggered by Porphyromonas gingivalis (P. gingivalis) is crucial for dental stability. Capsaicin, known as the pungent ingredient of chili peppers, can activate key signaling molecules involved in osteogenic process. However, the effect of capsaicin on osteogenesis of periodontal ligament stem cells (PDLSCs) under inflammation remains elusive.

METHODS

P. gingivalis culture suspension was added to mimic the inflammatory status after capsaicin pretreatment. The effects of capsaicin on the osteogenesis of PDLSCs, as well as mitochondrial morphology, Ca2+ level, reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and osteogenesis-regulated protein expression levels were analyzed. Furthermore, a mouse experimental periodontitis model was established to evaluate the effect of capsaicin on alveolar bone resorption and the expression of osteogenesis-related proteins.

RESULTS

Under P. gingivalis stimulation, capsaicin increased osteogenesis of PDLSCs. Not surprisingly, capsaicin rescued the damage to mitochondrial morphology, decreased the concentration of intracellular Ca2+ and ROS, enhanced MMP and activated phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway. The in vivo results showed that capsaicin significantly attenuated alveolar bone loss and augmented the expression of bone associated proteins.

CONCLUSION

Capsaicin increases osteogenesis of PDLSCs under inflammation and reduces alveolar bone resorption in mouse experimental periodontitis.

Harnessing the power of bee venom for therapeutic and regenerative medical applications: an updated review

Honeybees have been helpful insects since ancient centuries, and this benefit is not limited to being a honey producer only. After the bee stings a person, pain, and swelling occur in this place, due to the effects of bee venom (BV). This is not a poison in the total sense of the word because it has many benefits, and this is due to its composition being rich in proteins, peptides, enzymes, and other types of molecules in low concentrations that show promise in the treatment of numerous diseases and conditions. BV has also demonstrated positive effects against various cancers, antimicrobial activity, and wound healing versus the human immunodeficiency virus (HIV). Even though topical BV therapy is used to varying degrees among countries, localized swelling or itching are common side effects that may occur in some patients. This review provides an in-depth analysis of the complex chemical composition of BV, highlighting the diverse range of bioactive compounds and their therapeutic applications, which extend beyond the well-known anti-inflammatory and pain-relieving effects, showcasing the versatility of BV in modern medicine. A specific search strategy was followed across various databases; Web of sciences, Scopus, Medline, and Google Scholar including in vitro and in vivo clinical studies.to outline an overview of BV composition, methods to use, preparation requirements, and Individual consumption contraindications. Furthermore, this review addresses safety concerns and emerging approaches, such as the use of nanoparticles, to mitigate adverse effects, demonstrating a balanced and holistic perspective. Importantly, the review also incorporates historical context and traditional uses, as well as a unique focus on veterinary applications, setting it apart from previous works and providing a valuable resource for researchers and practitioners in the field.

The role of periodontitis in cancer development, with a focus on oral cancers

Periodontitis is a severe gum infection that begins as gingivitis and can lead to gum recession, bone loss, and tooth loss if left untreated. It is primarily caused by bacterial infection, which triggers inflammation and the formation of periodontal pockets. Notably, periodontitis is associated with systemic health issues and has been linked to heart disease, diabetes, respiratory diseases, adverse pregnancy outcomes, and cancers. Accordingly, the presence of chronic inflammation and immune system dysregulation in individuals with periodontitis significantly contributes to the initiation and progression of various cancers, particularly oral cancers. These processes promote genetic mutations, impair DNA repair mechanisms, and create a tumor-supportive environment. Moreover, the bacteria associated with periodontitis produce harmful byproducts and toxins that directly damage the DNA within oral cells, exacerbating cancer development. In addition, chronic inflammation not only stimulates cell proliferation but also inhibits apoptosis, causes DNA damage, and triggers the release of pro-inflammatory cytokines. Collectively, these factors play a crucial role in the progression of cancer in individuals affected by periodontitis. Further, specific viral and bacterial agents, such as hepatitis B and C viruses, human papillomavirus (HPV), Helicobacter pylori (H. pylori), and Porphyromonas gingivalis, contribute to cancer development through distinct mechanisms. Bacterial infections have systemic implications for cancer development, while viral infections provoke immune and inflammatory responses that can lead to genetic mutations. This review will elucidate the link between periodontitis and cancers, particularly oral cancers, exploring their underlying mechanisms to provide insights for future research and treatment advancements.

Anadenanthera colubrina regulated LPS-induced inflammation by suppressing NF-κB and p38-MAPK signaling pathways

We aimed to determine the chemical profile and unveil Anadenanthera colubrina (Vell.) Brenan standardized extract effects on inflammatory cytokines expression and key proteins from immunoregulating signaling pathways on LPS-induced THP-1 monocyte. Using the RT-PCR and Luminex Assays, we planned to show the gene expression and the levels of IL-8, IL-1β, and IL-10 inflammatory cytokines. Key proteins of NF-κB and MAPK transduction signaling pathways (NF-κB, p-38, p-NF-κB, and p-p38) were detected by Simple Western. Using HPLC-ESI-MSn (High-Performance Liquid-Chromatography) and HPLC-HRESIMS, we showed the profile of the extract that includes an opus of flavonoids, including the catechins, quercetin, kaempferol, and the proanthocyanidins. Cell viability was unaffected up to 250 µg/mL of the extract (LD50 = 978.7 µg/mL). Thereafter, the extract's impact on the cytokine became clear. Upon LPS stimuli, in the presence of the extract, gene expression of IL-1β and IL-10 were downregulated and the cytokines expression of IL-1β and IL-10 were down an upregulated respectively. The extract is involved in TLR-4-related NF-κB/MAPK pathways; it ignited phosphorylation of p38 and NF-κB, orchestrating a reduced signal intensity. Therefore, Anadenanthera colubrina's showed low cytotoxicity and profound influence as a protector against the inflammation, modulating IL-1β and IL-10 inflammatory cytokines gene expression and secretion by regulating intracellular NF-κB and p38-MAPK signaling pathways.

Periodontal pathogens and cancer development

Increasing evidence suggests a significant association between periodontal disease and the occurrence of various cancers. The carcinogenic potential of several periodontal pathogens has been substantiated in vitro and in vivo. This review provides a comprehensive overview of the diverse mechanisms employed by different periodontal pathogens in the development of cancer. These mechanisms induce chronic inflammation, inhibit the host's immune system, activate cell invasion and proliferation, possess anti-apoptotic activity, and produce carcinogenic substances. Elucidating these mechanisms might provide new insights for developing novel approaches for tumor prevention, therapeutic purposes, and survival improvement.

Platr3/NUDT21/NF-κB Axis Mediates P. gingivalis-Suppressed Cementoblast Mineralization

Porphyromonas gingivalis (P. gingivalis) is one of the major pathogens causing periodontitis and apical periodontitis (AP). Long noncoding RNA (lncRNA) can regulate cellular mineralization and inflammatory diseases. The aim of this study was to investigate the role and mechanism of lncRNA in P. gingivalis-stimulated cementoblast mineralization. In vivo, C57BL/6 mice were divided into the healthy, the AP, and AP + P. gingivalis groups (n = six mice per group). Micro computed tomography, immunohistochemistry staining, and fluorescence in situ hybridization were used to observe periapical tissue. In vitro, cementoblasts were treated with osteogenic medium or P. gingivalis. Pluripotency associated transcript 3 (Platr3), interleukin 1 beta (IL1B), and osteogenic markers were analyzed by quantitative real-time polymerase chain reaction and western blot. RNA pull-down and RNA immunoprecipitation assays were used to detect proteins that bind to Platr3. RNA sequencing was performed in Platr3-silenced cementoblasts. In vivo, P. gingivalis promoted periapical tissue destruction and IL1B expression, but inhibited Platr3 expression. In vitro, P. gingivalis facilitated IL1B expression (P < 0.001), whereas suppressed the expression of Platr3 (P < 0.001) and osteogenic markers (P < 0.01 or 0.001). In contrast, Platr3 overexpression alleviated the repressive effect of P. gingivalis on cementoblast mineralization (P < 0.01 or 0.001). Furthermore, Platr3 bound to nudix hydrolase 21 (NUDT21) and regulated the nuclear factor-κB (NF-κB) signaling pathway. Knocking down NUDT21 suppressed osteogenic marker expression and activated the above signaling pathway. Collectively, the results elucidated that Platr3 mediated P. gingivalis-suppressed cementoblast mineralization through the NF-κB signaling pathway by binding to NUDT21.

Preventive effect of Lacticaseibacillus paracasei LMT18-32 on Porphyromonas gingivalis induced periodontitis

Periodontitis is a severe gum infection leading to chronic inflammation in the gums, damage of tissues around teeth, and destruction of alveolar bones. Porphyromonas gingivalis is the major causative pathogen that induces periodontitis. Numerous probiotic bacteria are reported to produce antibacterial substances against pathogens especially oral pathogens, and these are proposed as preventive measures for periodontitis. In this study, Lacticaseibacillus paracasei LMT18-32 was evaluated and its antibacterial activity against P. gingivalis, and antioxidant activity in vitro were established. In addition, when L. paracasei LMT18-32 was administered to periodontitis induced mice, it successfully alleviated the alveolar bone loss and suppressed induced expression of proinflammatory and tissue destruction related genes in the gingival tissue. In conclusion, L. paracasei LMT18-32 is proposed as a potential probiotics to prevent periodontitis.

[Porphyromonas gingivalis infection facilitates immune escape of esophageal cancer by enhancing YTHDF2-mediated Fas degradation]

OBJECTIVE

To investigate the effect of Porphyromonas gingivalis (Pg) infection on immune escape of oesophageal cancer cells and the role of YTHDF2 and Fas in this regulatory mechanism.

METHODS

We examined YTHDF2 and Fas protein expressions in esophageal squamous cell carcinoma (ESCC) tissues with and without Pg infection using immunohistochemistry and in Pg-infected KYSE150 cells using Western blotting. The interaction between YTHDF2 and Fas was investigated by co-immunoprecipitation (Co-IP). Pg-infected KYSE150 cells with lentivirus-mediated YTHDF2 knockdown were examined for changes in expression levels of YTHDF2, cathepsin B (CTSB), Fas and FasL proteins, and the effect of E64 (a cathepsin inhibitor) on these proteins were observed. After Pg infection and E64 treatment, KYSE150 cells were co-cultured with human peripheral blood mononuclear cells (PBMCs), and the expressions of T cell-related effector molecules were detected by flow cytometry.

RESULTS

ESCC tissues and cells with Pg infection showed significantly increased YTHDF2 expression and lowered Fas expression. The results of Co-IP demonstrated a direct interaction between YTHDF2 and Fas. In Pg-infected KYSE150 cells with YTHDF2 knockdown, the expression of CTSB was significantly reduced while Fas and FasL expressions were significantly increased. E64 treatment of KYSE150 cells significantly decreased the expression of CTSB without affecting YTHDF2 expression and obviously increased Fas and FasL expressions. Flow cytometry showed that in Pg-infected KYSE150 cells co-cultured with PBMCs, the expressions of Granzyme B and Ki67 were significantly decreased while PD-1 expression was significantly enhanced.

CONCLUSION

Pg infection YTHDF2-dependently regulates the expression of Fas to facilitate immune escape of esophageal cancer and thus promoting cancer progression, suggesting the key role of YTHDF2 in regulating immune escape of esophageal cancer.

Galectin-3 inhibition alleviated LPS-induced periodontal inflammation in gingival fibroblasts and experimental periodontitis mice

OBJECTIVES

Clinical studies have confirmed that galectin-3 (Gal-3) levels are significantly elevated in periodontitis patients. The present study aimed to explore the effects of Gal-3 inhibition on periodontal inflammation in vitro and in vivo.

METHODS

Human gingival fibroblasts (HGFs) with or without Gal-3 knockdown were stimulated by lipopolysaccharide (LPS), and a ligation-induced mouse periodontitis model treated with a Gal-3 inhibitor was established. Hematoxylin-eosin (H&E) and immunohistochemistry (IHC) staining were used to evaluate Gal-3 levels in gingival tissues. Quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect Gal-3, interleukin (IL)-6, IL-8, and C-C motif ligand 2 (CCL2) expression. Immunofluorescence and western blotting were used to detect NF-κB and ERK signaling pathway activation. Micro-computed tomography was used to analyse the degree of bone loss.

RESULTS

Gal-3 was significantly up-regulated in inflamed gingival tissues and LPS-induced HGFs. Gal-3 knockdown markedly decreased LPS-induced IL-6, IL-8, and CCL2 expression and blocked NF-κB and ERK signaling pathway activation in HGFs. In the mouse periodontitis model, Gal-3 inhibition significantly alleviated IL-1β and IL-6 infiltration in gingival tissue and mitigated periodontal bone loss.

CONCLUSIONS

Gal-3 inhibition notably alleviated periodontal inflammation partly through blocking NF-κB and ERK signaling pathway activation.

Dysbiosis linking periodontal disease and oral squamous cell carcinoma-A brief narrative review

An association between periodontal disease and oral squamous cell carcinoma (OSCC) has been recognized. However, there is no causal relationship between the two. The polymicrobial etiology of periodontal disease is confirmed, and so are the proven etiological factors for OSCC. Inflammation lies at the core of periodontal pathogenesis induced by the putative microbes. OSCC has inflammatory overtures in its pathobiology. Bacterial species involved in periodontal disease have been extensively documented and validated. The microbial profile in OSCC has been explored with no specific conclusions. The scientific reasoning to link a common microbial signature that connects periodontal disease to OSCC has led to many studies but has not provided conclusive evidence. Therefore, it would be beneficial to know the status of any plausible microbiota having a similarity in periodontal disease and OSCC. This brief review attempted to clarify the existence of a dysbiotic "fingerprint" that may link these two diseases. The review examined the literature with a focused objective of identifying periodontal microbial profiles in OSCC that could provide insights into pathogen commonality. The review concluded that there is great diversity in microbial association, but important bacterial species that correlate with periodontal disease and OSCC are forthcoming.

The antimicrobial activity of tea tree oil (Melaleuca alternifolia) and its metal nanoparticles in oral bacteria

Tea tree (Melaleuca alternifolia) oil (TTO) is an antimicrobial agent, and hence, its use in fabricating nanoparticles (NP) may be useful in providing more efficacious antimicrobial agents. The current research aimed to test the antimicrobial efficacy of TTO and its TTO-Metal-NPs against oral microbes: Porphyromonas gingivalis, Enterococcus faecalis, and Streptococcus mutans. The antimicrobial activity of TTO and zinc (Zn) and iron (Fe) nanoparticles (NPs) and the combined effects of antimicrobial agents were investigated using agar well diffusion assays. Fourier-transform infrared spectroscopy (FT-IR) was used to identify the phyto-constituents of TTO. Field emission scanning electron microscopy (FE-SEM), dynamic light scatter (DLS), and zeta potential were utilized to analyze the biogenic nanoparticles' morphology, size, and potential. The antimicrobial mode of action was determined by assessing the morphological changes under scanning electron microscopy (SEM). The TTO extracts converted Zn and Fe ions to NPs, having an average size of 97.50 (ZnNPs) and 102.4 nm (FeNPs). All tested agents had significant antibacterial efficacy against the tested oral microbes. However, the TTO extract was more efficacious than the NPs. Combination treatment of TTO with antibiotics resulted in partial additive effects against P. gingivalis and partial antagonistic effects against E. faecalis, S. mutans, and common mouthwashes (Oral B and chlorhexidine). TTO and NP-treated bacteria underwent morphological changes on treatment. M. alternifolia phytochemicals could be useful for further research and development of antimicrobial NPs. The current study highlights the variance in activity observed for different types of bacteria and antagonistic effects seen with common mouthwashes, which represent a threat to therapeutic efficacy and heighten the risk of clinical microbial resistance.

Porphyromonas gingivalis Vaccine: Antigens and Mucosal Adjuvants

Porphyromonas gingivalis (Pg), a Gram-negative anaerobic bacterium found in dental plaque biofilm within periodontal pockets, is the primary pathogenic microorganism responsible for chronic periodontitis. Infection by Pg significantly impacts the development and progression of various diseases, underscoring the importance of eliminating this bacterium for effective clinical treatment. While antibiotics are commonly used to combat Pg, the rise of antibiotic resistance poses a challenge to complete eradication. Thus, the prevention of Pg infection is paramount. Research suggests that surface antigens of Pg, such as fimbriae, outer membrane proteins, and gingipains, can potentially be utilized as vaccine antigens to trigger protective immune responses. This article overviews these antigens, discusses advancements in mucosal adjuvants (including immunostimulant adjuvants and vaccine-delivery adjuvants), and their application in Pg vaccine development. Furthermore, the review examines the advantages and disadvantages of different immune pathways and common routes of Pg vaccine immunization. By summarizing the current landscape of Pg vaccines, addressing existing challenges, and highlighting the potential of mucosal vaccines, this review offers new insights for the advancement and clinical implementation of Pg vaccines.

The Anti-Inflammatory Effect of SDF-1 Derived Peptide on Porphyromonas gingivalis Infection via Regulation of NLRP3 and AIM2 Inflammasome

(1) Background: Peptides are appealing as pharmacological materials because they are easily produced, safe, and tolerable. Despite increasing gum-care awareness, periodontitis is still prevalent and is influenced by factors like high sugar consumption, smoking, and aging. Porphyromonas gingivalis is considered a major etiologic agent of periodontitis and activates the NLR family pyrin domain containing 3 (NLRP3) but is absent in melanoma 2 (AIM2) inflammasomes, resulting in pro-inflammatory cytokine release. (2) Methods: We examined the anti-inflammatory effects of 18 peptides derived from human stromal cell-derived factor-1 (SDF-1) on THP-1 macrophages. Inflammation was induced by P. gingivalis, and the anti-inflammatory effects were analyzed using molecular biological techniques. In a mouse periodontitis model, alveolar bone resorption was assessed using micro-CT. (3) Results: Of the 18 SDF-1-derived peptides, S10 notably reduced IL-1β and TNF-α secretion. S10 also diminished the P. gingivalis-induced expression of NLRP3, AIM2, ASC (apoptosis-associated speck-like protein), caspase-1, and IL-1β. Furthermore, S10 attenuated the enhanced TLR (toll-like receptor) signaling pathway and decreased the phosphorylation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs). In addition, S10 mitigated alveolar bone loss in our P. gingivalis-induced mouse model of periodontitis. (4) Conclusions: S10 suppressed TLR/NF-κB/NLRP3 inflammasome signaling and the AIM2 inflammasome in our P. gingivalis-induced murine periodontitis model, which suggests that it has potential use as a therapeutic treatment for periodontitis.

Persistent infection with Porphyromonas gingivalis increases the tumorigenic potential of human immortalised oral epithelial cells through ZFP36 inhibition

The association between Porphyromonas gingivalis infection and oral squamous cell carcinoma (OSCC) has been established by numerous epidemiological studies. However, the underlying mechanism specific to this connection remains unclear. By bioinformatical analysis, we identified ZFP36 as a potentially significant co-expressed gene in both the OSCC gene database and the persistent infection model of P. gingivalis. To further investigate the role of ZFP36, we established a cell model that human immortalized oral epithelial cells (HIOECs) that were sustainedly infected by P. gingivalis (MOI = 1) for a duration of 30 weeks. Our findings indicated that sustained infection with P. gingivalis inhibited the expression of ZFP36 protein and induced changes in the biological behaviour of HIOECs. The mechanism investigation demonstrated the potential role of ZFP36 in regulating the cancer-related biological behaviour of HIOECs. Subsequent studies revealed that highly expressed CCAT1 could serve as a molecular scaffold in the formation of the ZFP36/CCAT1/MK2 complex. This complex formation enhanced the binding abundance of MK2 and ZFP36, thereby promoting the inhibition of ZFP36 protein phosphorylation. To summarize, low expression of ZFP36 protein under persistent P. gingivalis infection enhances the cancer-related biological behaviour of HIOECs.

Multifunctional role of oral bacteria in the progression of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of liver disorders of varying severity, ultimately leading to fibrosis. This spectrum primarily consists of NAFL and non-alcoholic steatohepatitis. The pathogenesis of NAFLD is closely associated with disturbances in the gut microbiota and impairment of the intestinal barrier. Non-gut commensal flora, particularly bacteria, play a pivotal role in the progression of NAFLD. Notably, Porphyromonas gingivalis, a principal bacterium involved in periodontitis, is known to facilitate lipid accumulation, augment immune responses, and induce insulin resistance, thereby exacerbating fibrosis in cases of periodontitis-associated NAFLD. The influence of oral microbiota on NAFLD via the "oral-gut-liver" axis is gaining recognition, offering a novel perspective for NAFLD management through microbial imbalance correction. This review endeavors to encapsulate the intricate roles of oral bacteria in NAFLD and explore underlying mechanisms, emphasizing microbial control strategies as a viable therapeutic avenue for NAFLD.

Dynamic hydrogel-metal-organic framework system promotes bone regeneration in periodontitis through controlled drug delivery

Periodontitis is a prevalent chronic inflammatory disease, which leads to gradual degradation of alveolar bone. The challenges persist in achieving effective alveolar bone repair due to the unique bacterial microenvironment's impact on immune responses. This study explores a novel approach utilizing Metal-Organic Frameworks (MOFs) (comprising magnesium and gallic acid) for promoting bone regeneration in periodontitis, which focuses on the physiological roles of magnesium ions in bone repair and gallic acid's antioxidant and immunomodulatory properties. However, the dynamic oral environment and irregular periodontal pockets pose challenges for sustained drug delivery. A smart responsive hydrogel system, integrating Carboxymethyl Chitosan (CMCS), Dextran (DEX) and 4-formylphenylboronic acid (4-FPBA) was designed to address this problem. The injectable self-healing hydrogel forms a dual-crosslinked network, incorporating the MOF and rendering its on-demand release sensitive to reactive oxygen species (ROS) levels and pH levels of periodontitis. We seek to analyze the hydrogel's synergistic effects with MOFs in antibacterial functions, immunomodulation and promotion of bone regeneration in periodontitis. In vivo and in vitro experiment validated the system's efficacy in inhibiting inflammation-related genes and proteins expression to foster periodontal bone regeneration. This dynamic hydrogel system with MOFs, shows promise as a potential therapeutic avenue for addressing the challenges in bone regeneration in periodontitis.

Mitochondrial ROS participates in Porphyromonas gingivalis-induced pyroptosis in cementoblasts

This study aimed to investigate correlation between mitochondrial reactive oxygen species and Porphyromonas gingivalis in the process of cementoblast pyroptosis. Lactate dehydrogenase activity assay, enzyme-linked immunosorbent assay, western blotting and flow cytometry analysis were utilized to explore whether Porphyromonas gingivalis triggered pyroptosis in cementoblasts. Reactive oxygen species and mitochondrial reactive oxygen species were detected using flow cytometry and fluorescence staining. The effect of mitochondrial reactive oxygen species on the Porphyromonas gingivalis-induced pyroptosis of cementoblasts was assessed by Mito-Tempo, mitochondrion-targeted superoxide dismutase mimetic. Phosphorylation levels of p65 were measured by western blotting. SC75741, a nuclear factor-kappa B inhibitor, was added to block the nuclear factor-kappa B in the Porphyromonas gingivalis-infected cementoblasts. Porphyromonas gingivalis triggered pyroptosis of cementoblasts, and an elevation in reactive oxygen species generation in the mitochondria was observed. Inhibition of mitochondrial reactive oxygen species reduced pyroptosis and nuclear factor-kappa B signaling pathway mediated the pyroptotic cell death in Porphyromonas gingivalis-infected cementoblasts. Together, our findings demonstrate that mitochondrial reactive oxygen species increased by Porphyromonas gingivalis participated in the pyroptosis of cementoblasts. Targeting mitochondrial reactive oxygen species may offer therapeutic strategies for root surface remodeling or periodontal regeneration.

Real-Time PCR Method as Diagnostic Tool for Detection of Periodontal Pathogens in Patients with Periodontitis

The most common type of periodontal disease is chronic periodontitis, an inflammatory condition caused by pathogenic bacteria in subgingival plaque. The aim of our study was the development of a real-time PCR test as a diagnostic tool for the detection and differentiation of five periodontopathogenic bacteria, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, and Treponema denticola, in patients with periodontitis. We compared the results of our in-house method with the micro-IDent® semiquantitative commercially available test based on the PCR hybridization method. DNA was isolated from subgingival plaque samples taken from 50 patients and then analyzed by both methods. Comparing the results of the two methods, they show a specificity of 100% for all bacteria. The sensitivity for A. actinomycetemcomitans was 97.5%, for P. gingivalis 96.88%, and for P. intermedia 95.24%. The sensitivity for Tannerella forsythia and T. denticola was 100%. The Spearman correlation factor of two different measurements was 0.976 for A. actinomycetemcomitans, 0.967 for P. gingivalis, 0.949 for P. intermedia, 0.966 for Tannerella forsythia, and 0.917 for T. denticola. In conclusion, the in-house real-time PCR method developed in our laboratory can provide information about relative amount of five bacterial species present in subgingival plaque in patients with periodontitis. It is likely that such a test could be used in dental diagnostics in assessing the efficacy of any treatment to reduce the bacterial burden.

Comprehensive comparative analysis of the periodontal pathogen Porphyromonas gingivalis: exploring the pan-genome, the reconstruction of the gene regulatory network and genome-scale metabolic network

Porphyromonas gingivalis is a nonmotile, obligate anaerobic, Gram-negative bacterium known for its association with periodontal disease and its involvement in systemic diseases such as atherosclerosis, cardiovascular disease, colon cancer, and Alzheimer's disease. This bacterium produces several virulence factors, including capsules, fimbriae, lipopolysaccharides, proteolytic enzymes, and hemagglutinins. A comparative genomic analysis revealed the open pangenome of P. gingivalis and identified complete type IV secretion systems in strain KCOM2805 and almost complete type VI secretion systems in strains KCOM2798 and ATCC49417, which is a new discovery as previous studies did not find the proteins involved in secretion systems IV and VI. Conservation of some virulence factors between different strains was observed, regardless of their genetic diversity and origin. In addition, we performed for the first time a reconstruction analysis of the gene regulatory network, identifying transcription factors and proteins involved in the regulatory mechanisms of bacterial pathogenesis. In particular, QseB regulates the expression of hemagglutinin and arginine deaminase, while Rex may suppress the release of gingipain through interactions with PorV and the formatum/nitrate transporter. Our study highlights the central role of conserved virulence factors and regulatory pathways, particularly QseB and Rex, in P. gingivalis and provides insights into potential therapeutic targets.

Diosgenin prevents periodontitis by inhibiting inflammation and promoting osteogenic differentiation

Diosgenin, an essential dietary steroidal sapogenin, possess multiple pharmacological activities. This study aimed to assess the effects of diosgenin on periodontitis and elucidate the mechanisms. Lipopolysaccharide (LPS)-stimulated human periodontal ligament stem cells (hPDLCs) and a Porphyromonas gingivalis (P.g) plus ligation-induced animal model were used for in vitro and in vivo studies, respectively. Inflammatory responses, nuclear factor κ-B (NF-κB) signaling and osteogenesis-related markers were measured both in LPS-stimulated hPDLSCs and in gingival tissue of periodontitis rats. Treatment with diosgenin significantly inhibited the production of tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and interleukin (IL)-6 and the activation of NF-κB pathway in LPS-stimulated hPDLSCs. Further, treatment with diosgenin enhanced the expression of osteoblast-related genes and increased the osteogenic differentiation capacity. Further, activation NF-κB pathway largely abolished the protective effects of diosgenin. Consistent with the in vitro studies, in vivo studies showed that administering diosgenin to periodontitis rats significantly lowered the levels of the TNF-α, IL-1β, and IL-6 and the inflammatory transcription factor NF-κB in gingival tissue. In addition, osteoblast-related genes were promoted. Diosgenin attenuates periodontitis by adjusting NF-κB signaling to inhibit inflammatory effects and promoting osteogenesis, suggesting diosgenin might be developed as a therapeutic strategy for treating periodontitis in the future.

Neutrophil response to Porphyromonas gingivalis is modulated by low-level laser application

OBJECTIVES

Neutrophil response is critical in inflammatory regulation and immune response to bacterial infections. During periodontal disease, pathogenic bacteria lead to exaggerated neutrophil responses. We hypothesized that low-level laser application (LLLT), therapeutic strategy for dampening inflammatory processes, will regulate neutrophil activity in response to periodontopathogens.

MATERIALS AND METHODS

The impact of LLLT on neutrophil responses was measured by light delivered at wavelength of 850 nm. The direct effect of LLLT on P. gingivalis A7436 was determined by flow cytometry using LIVE/DEADTM Cell Vitality kit. The phagocytosis of P. gingivalis A7436 by human neutrophils was measured using flow cytometry. Superoxide generation was measured by cytochrome-C-reduction in the presence of N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP; 1 mM). Cytokine release by neutrophils was measured by multiplex immunoassay.

RESULTS

The phagocytosis of P. gingivalis by primary human neutrophils was significantly reduced in response to LLLT (p < 0.05). While LLLT led to increased superoxide production in neutrophils that were not challenged by P. gingivalis, it dampened the increased superoxide and IL-6 release by the neutrophils in response to P. gingivalis. LLLT did not directly affect the viability of P. gingivalis.

CONCLUSION

These results suggested that LLLT can provide therapeutic strategy in periodontal disease, regulating the neutrophil response to P. gingivalis.

Pretreatment periodontitis is predictive of a poorer prognosis after esophagectomy for esophageal cancer

BACKGROUND

Poor oral health is an independent risk factor for upper-aerodigestive tract cancers, including esophageal cancer. Several studies have investigated short-term outcomes after esophagectomy and the impact of periodontal disease, but few have examined the impact of periodontal disease on long-term outcomes. The purpose of this study was to investigate the rate of periodontitis among esophagectomy patients and the prognostic value of periodontitis and its effect on prognosis after esophagectomy.

METHODS

A total of 508 patients who underwent esophagectomy received oral health care from a dentist before cancer treatment at Akita University Hospital between January 2009 and December 2021. We assessed the presence and severity of the patients' periodontitis and divided them into no-periodontitis, mild periodontitis, severe periodontitis and edentulous jaw groups. We then assessed 10-year overall survival (OS) and disease-specific survival (DSS) and determined whether periodontitis was an independent prognostic factor affecting OS and DSS.

RESULTS

We found that 101 (19.9%) patients had no periodontitis, 207 (40.8%) had mild periodontitis, 176 (34.6%) had severe periodontitis requiring tooth extraction, and 24 (4.7%) had edentulous jaw. Both OS and DSS were significantly poorer in the periodontitis than no-periodontitis group (p < 0.001). In detail, the edentulous jaw group had the poorest prognosis (p < 0.001). Multivariate analysis showed that periodontitis was an independent risk factor affecting OS and DSS.

CONCLUSION

Esophageal cancer patients had a high prevalence of periodontitis. Moreover, the presence of periodontitis and severity of periodontitis are independent risk factors contributing to a poorer prognosis after esophagectomy.

Caspase-3/GSDME-mediated pyroptosis leads to osteogenic dysfunction of osteoblast-like cells

OBJECTIVE

Cell pyroptosis is implicated in progressive bone loss in dental inflammatory diseases. We induced caspase-3/Gasdermin E (GSDME)-mediated pyroptosis in osteoblast-like cells and evaluated the effects on osteogenesis.

MATERIALS AND METHODS

Osteoblast-like cells were treated with various concentrations of sodium butyrate (NaB) to identify the most appropriate for inducing caspase-3/GSDME-mediated pyroptosis. Cells were divided into control, NaB and NaB+Ac-DEVD-CHO (specific caspase-3 inhibitor) groups. Pyroptosis level was evaluated by immunofluorescence, morphological observation, flow cytometry, lactate dehydrogenase (LDH) release assays, mRNA and protein levels of pyroptosis-related markers. Then, inflammation level, osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) expression and osteogenic function were detected.

RESULTS

Treatment with 10 mM NaB increased caspase-3 expression, GSDME cleavage, LDH release and the number of pyroptotic cells, with morphologic changes, indicating GSDME-mediated pyroptosis induction. The pyroptosis-related changes were abolished by caspase-3 inhibition. Caspase-3/GSDME-mediated pyroptosis triggered the expression of inflammatory cytokines and RANKL, downregulated alkaline phosphatase (ALP) activity, mineralisation level, mRNA and protein levels of multiple osteogenic markers. These effects were partly reversed by Ac-DEVD-CHO.

CONCLUSION

Caspase-3/GSDME-mediated pyroptosis induced by NaB activated the inflammatory response, reduced osteogenic differentiation and disturbed OPG/RANKL axis, leading to osteogenic dysfunction in osteoblast-like cells.

Fourier transform infrared spectroscopy and machine learning for Porphyromonas gingivalis detection in oral bacteria

Porphyromonas gingivalis, a Gram-negative anaerobic bacillus, is the primary pathogen in periodontitis. Herein, we cultivated strains of oral bacteria, including P. gingivalis and the oral commensal bacteria Actinomyces viscosus and Streptococcus mutans, and recorded the infrared absorption spectra of the gases released by the cultured bacteria at a resolution of 0.5 cm-1 within the wavenumber range of 500-7500 cm-1. From these spectra, we identified the infrared wavenumbers associated with characteristic absorptions in the gases released by P. gingivalis using a decision tree-based machine learning algorithm. Finally, we compared the obtained absorbance spectra of ammonia (NH3) and carbon monoxide (CO) using the HITRAN database. We observed peaks at similar positions in the P. gingivalis gases, NH3, and CO spectra. Our results suggest that P. gingivalis releases higher amounts of NH3 and CO than A. viscosus and S. mutans. Thus, combining Fourier transform infrared spectroscopy with machine learning enabled us to extract the specific wavenumber range that differentiates P. gingivalis from a vast dataset of peak intensity ratios. Our method distinguishes the gases from P. gingivalis from those of other oral bacteria and provides an effective strategy for identifying P. gingivalis in oral bacteria. Our proposed methodology could be valuable in clinical settings as a simple, noninvasive pathogen diagnosis technique.

Antimicrobial efficacy of antiplaque agents of common toothpastes against Porphyromonas gingivalis and Streptococcus oralis: An in vitro study

Background

This study was designed to evaluate the antimicrobial activity of common gum protection and antiplaque toothpastes against Porphyromonas gingivalis (P. gingivalis) and Streptococcus oralis (S. oralis) as important periodontal pathogens.

Materials and Methods

This experimental study investigated the antimicrobial activity of 15 commonly used toothpastes from different companies on the two common types of periopathogens, S. oralis and P. gingivalis . The antimicrobial activity of toothpaste was evaluated at three concentrations of 100%, 50%, and 25% and analyzed by agar well diffusion plate method and zone of inhibition. The obtained data were compared and statistically analyzed by SPSS software using one-way ANOVA and the least significant difference post hoc tests (α = 0.05).

Results

One-way ANOVA showed that the mean diameter of the two-bacterial zone of inhibition was significantly different at 100%, 50%, and 25% concentrations of toothpastes (P < 0.001). In general, the mean diameter of the zone of inhibition was greater at 100% concentration than the other two concentrations in all toothpastes. The highest zone of inhibition of the S. oralis was in the toothpastes containing tin. Further, the highest zone of inhibition of P. gingivalis was found in the triclosan-containing toothpastes.

Conclusion

Toothpastes containing triclosan had the most antimicrobial activity against P. gingivalis . Moreover, toothpastes containing tin compounds had the most antimicrobial effect against S. oralis .

Electrospun L-Lysine/Amorphous Calcium Phosphate Loaded Core-Sheath Nanofibers for Managing Oral Biofilm Infections and Promoting Periodontal Tissue Repairment

Introduction

Periodontitis, a chronic inflammatory disease prevalent worldwide, is primarily treated through GTR for tissue regeneration. The efficacy of GTR, however, remains uncertain due to potential infections and the intricate microenvironment of periodontal tissue. Herein, We developed a novel core-shell structure multifunctional membrane using a dual-drug-loaded coaxial electrospinning technique (Lys/ACP-CNF), contains L-lysine in the outer layer to aid in controlling biofilms after GTR regenerative surgery, and ACP in the inner layer to enhance osteogenic performance for accelerating alveolar bone repair.

Methods

The biocompatibility and cell adhesion were evaluated through CCK-8 and fluorescence imaging, respectively. The antibacterial activity was assessed using a plate counting assay. ALP, ARS, and RT-qPCR were used to examine osteogenic differentiation. Additionally, an in vivo experiment was conducted on a rat model with acute periodontal defect and infection. Micro-CT and histological analysis were utilized to analyze the in vivo alveolar bone regeneration.

Results

Structural and physicochemical characterization confirmed the successful construction of the core-shell fibrous structure. Additionally, the Lys/ACP-CNF showed strong antibacterial coaggregation effects and induced osteogenic differentiation of PDLSCs in vitro. The in vivo experiment confirmed that Lys/ACP-CNF promotes new bone formation.

Conclusion

Lys/ACP-CNF rapidly exhibited excellent antibacterial activity, protected PDLSCs from infection, and was conducive to osteogenesis, demonstrating its potential application for clinical periodontal GTR surgery.

A Porphyromonas gingivalis hypothetical protein controlled by the type I-C CRISPR-Cas system is a novel adhesin important in virulence

The ability of many human pathogens to infect requires their ability to adhere to the host surfaces as a first step in the process. Porphyromonas gingivalis, a keystone oral pathogen, uses adhesins to adhere to the surface of the gingival epithelium and other members of the oral microbiome. In a previous study, we identified several proteins potentially linked to virulence whose mRNA levels are regulated by CRISPR-Cas type I-C. Among those, PGN_1547 was highly upregulated in the CRISPR-Cas 3 mutant. PGN_1547 is annotated as a hypothetical protein. Employing homology searching, our data support that PGN_1547 resembles an auto-transporter adhesin of P. gingivalis based on containing the DUF2807 domain. To begin to characterize the function of PGN_1547, we found that a deletion mutant displayed a significant decrease in virulence using a Galleria mellonela model. Furthermore, this mutant was significantly impaired in forming biofilms and attaching to the macrophage-like cell THP-1. Luminex revealed that the PGN_1547 mutant elicited a less robust cytokine and chemokine response from THP-1 cells, and TLR2 predominantly sensed that recombinant PGN_1547. Taken together, these findings broaden our understanding of the toolbox of virulence factors possessed by P. gingivalis. Importantly, PGN_1547, a hypothetical protein, has homologs in another member of the order Bacteroidales whose function is unknown, and our results could shed light on the role of this family of proteins as auto-transport adhesins in this phylogenetic group.IMPORTANCEPeriodontal diseases are among humans' most common infections, and besides their effect on the oral cavity, they have been associated with systemic inflammatory conditions. Among members of the oral microbiome implicated in the development of periodontitis, Porphyromonas gingivalis is considered a keystone pathogen. We have identified a new adhesin that acts as a virulence factor, PGN_1547, which contains the DUF2807 domain, which belongs to the putative auto-transporter adhesin, head GIN domain family. Deletion of this gene lowers the virulence of P. gingivalis and impacts the ability of P. gingivalis to form biofilm and attach to host cells. Furthermore, the broad distribution of these receptors in the order Bacteroidales suggests their importance in colonization by this important group of organisms.

Porphyromonas gingivalis-induced hematogenous disseminated severe pneumonia: a case report

Porphyromonas gingivalis, a gram-negative oral anaerobe among more than more than 500 bacterial species that colonizing the oral cavity, is involved in the pathogenesis and prototypic polybacterial consortium of periodontitis. It is mainly found in oral infections and rarely present in other organ diseases. Here, we describe a 43-year-old man with underlying diabetes who developed hematogenous disseminated severe pneumonia after P. gingivalis had invaded the blood. Next-generation sequencing of early alveolar lavage fluid and blood samples confirmed the diagnosis. The patient's lung infection improved after targeted antimicrobial treatment. He was successfully weaned from ventilatory support and transferred to the general ward. This case illustrates bacterial entry into the bloodstream of a patient with diabetes who had periodontal disease but did not maintain oral hygiene, leading to severe pneumonia. Periodontal disease is often ignored by the public, and it is difficult for critical care physicians to link severe pneumonia with periodontal disease. Thus, this case represents an important warning to critical care clinicians.

Association between periodontitis and endometriosis: a bidirectional Mendelian randomization study

Introduction

A potential association between periodontitis and endometriosis has been indicated in previous observational studies. Nevertheless, the causal link between these two disorders has not been clarified.

Methods

Based on publicly available genome-wide association study (GWAS) summary datasets, we conducted a bidirectional Mendelian randomization (MR) study to investigate the relationship between periodontitis and endometriosis and its subtypes. Single nucleotide polymorphisms (SNPs) strongly associated with candidate exposures at the genome-wide significance level (P < 5 × 10-8) were selected as instrumental variables (IVs). The inverse variance-weighted regression (IVW) was performed to estimate the causal effect of periodontitis on endometriosis. We further conducted two sensitivity analyses, MR-Egger and weighted median, to test the validity of our findings. The main results were replicated via data from the UK Biobank. Finally, a reverse MR analysis was performed to evaluate the possibility of reverse causality.

Results

The IVW method suggested that periodontitis was positively associated with endometriosis of the pelvic peritoneum (OR = 1.079, 95% CI = 1.016 to 1.146, P = 0.014). No causal association was indicated between periodontitis and other subtypes of endometriosis. In reversed analyses, no causal association between endometriosis or its subtypes and periodontitis was found.

Conclusions

Our study provided genetic evidence on the causal relationship between periodontitis and endometriosis of the pelvic peritoneum. More studies are necessary to explore the underlying mechanisms.

Colorimetric detection of oral bacteria using functionalized gold nanoparticles as a plasmonic biosensor array

Early detection of specific oral bacterial species would enable timely treatment and prevention of certain oral diseases. In this work, we investigated the sensitivity and specificity of functionalized gold nanoparticles for plasmonic sensing of oral bacteria. This approach is based on the aggregation of positively charged gold nanoparticles on the negatively charged bacteria surface and the corresponding localized surface plasmon resonance (LSPR) shift. Gold nanoparticles were synthesized in different sizes, shapes and functionalization. A biosensor array was developed consisting of spherical- and anisotropic-shaped (1-hexadecyl) trimethylammonium bromide (CTAB) and spherical mercaptoethylamine (MEA) gold nanoparticles. It was used to detect four oral bacterial species (Aggregatibacter actinomycetemcomitans, Actinomyces naeslundii, Porphyromonas gingivalis and Streptococcus oralis). The plasmonic response was measured and analysed using RGB and UV-vis absorbance values. Both methods successfully detected the individual bacterial species based on their unique responses to the biosensor array. We present an in-depth study relating the bacteria zeta potential and AuNP aggregation to plasmonic response. The sensitivity depends on multiple parameters, such as bacterial species and concentration as well as gold nanoparticle shape, concentration and functionalization.

Periodontitis aggravates COPD through the activation of γδ T cell and M2 macrophage

Chronic obstructive pulmonary disease (COPD) is a chronic systemic inflammatory disease with high morbidity and mortality. Periodontitis exacerbates COPD progression; however, the immune mechanisms by which periodontitis affects COPD remain unclear. Here, by constructing periodontitis and COPD mouse models, we demonstrated that periodontitis and COPD could mutually aggravate disease progression. For the first time, we found that the progression was associated with the activation of γδ T cells and M2 macrophages, and M2 polarization of macrophages was affected by γδ T cells activation. In the lung tissues of COPD with periodontitis, the activation of γδ T cells finally led to the increase of IL 17 and IFN γ expression and M2 macrophage polarization. Furthermore, we found that the periodontitis-associated bacteria Porphyromonas gingivalis (P. gingivalis) promoted the activation of γδ T cells and M2 macrophages ex vivo. The data from clinical bronchoalveolar lavage fluid (BALF) samples were consistent with the in vivo and ex vivo experiments. For the first time, our results identified the crucial role of γδ T-M2 immune mechanism in mediating periodontitis-promoted COPD progression. Therefore, targeting at periodontitis treatment and the γδ T-M2 immune mechanism might provide a new practical strategy for COPD prevention or control.IMPORTANCEPeriodontitis exacerbates chronic obstructive pulmonary disease (COPD) progression. For the first time, the current study identified that the impact of periodontitis on COPD progression was associated with the activation of γδ T cells and M2 macrophages and that M2 polarization of macrophages was affected by γδ T cells activation. The results indicated that targeting at periodontitis treatment and the γδ T-M2 immune mechanism might provide a new practical strategy for COPD prevention or control.

Intestinal Translocation of Live Porphyromonas gingivalis Drives Insulin Resistance

Periodontitis has been emphasized as a risk factor of insulin resistance-related systemic diseases. Accumulating evidence has suggested a possible "oral-gut axis" linking oral infection and extraoral diseases, but it remains unclear whether periodontal pathogens can survive the barriers of the digestive tract and how they play their pathogenic roles. The present study established a periodontitis mouse model through oral ligature plus Porphyromonas gingivalis inoculation and demonstrated that periodontitis aggravated diet-induced obesity and insulin resistance, while also causing P. gingivalis enrichment in the intestine. Metabolic labeling strategy validated that P. gingivalis could translocate to the gastrointestinal tract in a viable state. Oral administration of living P. gingivalis elicited insulin resistance, while administration of pasteurized P. gingivalis had no such effect. Combination analysis of metagenome sequencing and nontargeted metabolomics suggested that the tryptophan metabolism pathway, specifically indole and its derivatives, was involved in the pathogenesis of insulin resistance caused by oral administration of living P. gingivalis. Moreover, liquid chromatography-high-resolution mass spectrometry analysis confirmed that the aryl hydrocarbon receptor (AhR) ligands, mainly indole acetic acid, tryptamine, and indole-3-aldehyde, were reduced in diet-induced obese mice with periodontitis, leading to inactivation of AhR signaling. Supplementation with Ficz (6-formylindolo (3,2-b) carbazole), an AhR agonist, alleviated periodontitis-associated insulin resistance, in which the restoration of gut barrier function might play an important role. Collectively, these findings reveal that the oral-gut translocation of viable P. gingivalis works as a fuel linking periodontitis and insulin resistance, in which reduction of AhR ligands and inactivation of AhR signaling are involved. This study provides novel insight into the role of the oral-gut axis in the pathogenesis of periodontitis-associated comorbidities.

The osteogenic effects of sappanchalcone in vitro and in vivo

BACKGROUND AND OBJECTIVES

The utilization of natural products to enhance the function of periodontal ligament cells (PDLCs) has emerged as a popular area of research. Recent investigations have demonstrated that sappanchalcone (SC) possesses pharmacological properties such as anti-inflammatory and osteoprotective effects. This study aims to explore the impact of SC on the in vivo and in vitro osteogenic differentiation ability of PDLCs.

MATERIALS

Cell proliferation was quantified using the CCK-8 assay, while gene expression levels were assessed through qRT-PCR analysis. Osteoblast differentiation capacity was evaluated by employing Alizarin red staining (ARS), alkaline phosphatase (ALP) staining and western blot (WB) analysis. A rat model of periodontitis was established utilizing the tether-wire method. Micro-CT imaging and hematoxylin and eosin (HE) staining were employed to evaluate alveolar bone resorption. Masson's trichrome staining was utilized to observe fiber alignment, whereas immunohistochemistry (IHC) techniques were applied for detecting osteogenic and inflammatory factors.

RESULTS

The results from the CCK-8 assay indicate no observed cytotoxicity for concentrations of 1, 5, or 10 nM for SC treatment (p < .05), while qRT-PCR analysis demonstrates a significant decrease in inflammatory factors such as MMP-1 and IL-6 with treatment by SC (p < .05). Additionally, western blotting reveals an increase in protein expression levels of Runx2 and OPN within PDLCs treated with SC compared to control groups (p < .05), which is further supported by ARS and ALP staining indicating an increase in mineralized nodules formation along with elevated ALP content within these cells following treatment with this compound (p < .05). Finally, both HE staining as well as micro-CT imaging suggest potential benefits associated with using this compound including slowing alveolar bone resorption while simultaneously promoting junctional epithelium proliferation.

CONCLUSIONS

Our in vitro and in vivo findings suggest that SC can effectively enhance the inflammatory response of PDLCs and promote their osteogenic differentiation ability under inflammatory conditions, indicating its potential as a promising therapeutic agent for improving periodontal inflammation and bone formation.

Mitochondria: An Emerging Unavoidable Link in the Pathogenesis of Periodontitis Caused by Porphyromonas gingivalis

Porphyromonas gingivalis (P. gingivalis) is a key pathogen of periodontitis. Increasing evidence shows that P. gingivalis signals to mitochondria in periodontal cells, including gingival epithelial cells, gingival fibroblast cells, immune cells, etc. Mitochondrial dysfunction affects the cellular state and participates in periodontal inflammatory response through the aberrant release of mitochondrial contents. In the current review, it was summarized that P. gingivalis induced mitochondrial dysfunction by altering the mitochondrial metabolic state, unbalancing mitochondrial quality control, prompting mitochondrial reactive oxygen species (ROS) production, and regulating mitochondria-mediated apoptosis. This review outlines the impacts of P. gingivalis and its virulence factors on the mitochondrial function of periodontal cells and their role in periodontitis.

Loricrin and Cytokeratin Disorganisation in Severe Forms of Periodontitis

OBJECTIVE

The aim of this research was to investigate the role of the cornified epithelium, the outermost layer of the oral mucosa, engineered to prevent water loss and microorganism invasion, in severe forms of periodontitis (stage III or IV, grade C).

METHODS

Porphyromonas gingivalis, a major periodontal disease pathogen, can affect cornified epithelial protein expression through chronic activation of signal transducer and activator of transcription 6 (Stat6). We used a mouse model, Stat6VT, that mimics this to determine the effects of barrier defect on P gingivalis-induced inflammation, bone loss, and cornified epithelial protein expression, and compared histologic and immunohistologic findings with tissues obtained from human controls and patients with stage III and IV, grade C disease. Alveolar bone loss in mice was assessed using micro-computerised tomography, and soft tissue morphology was qualitatively and semi-quantitatively assessed by histologic examination for several proteins, including loricrin, filaggrin, cytokeratin 1, cytokeratin 14, a proliferation marker, a pan-leukocyte marker, as well as morphologic signs of inflammation. Relative cytokine levels were measured in mouse plasma by cytokine array.

RESULTS

In the tissues from patients with periodontal disease, there were greater signs of inflammation (rete pegs, clear cells, inflammatory infiltrates) and a decrease and broadening of expression of loricrin and cytokeratin 1. Cytokeratin 14 expression was also broader and decreased in stage IV. P gingivalis-infected Stat6VT mice showed greater alveolar bone loss in 9 out of 16 examined sites, and similar patterns of disruption to human patients in expression of loricrin and cytokeratins 1 and 14. There were also increased numbers of leukocytes, decreased proliferation, and greater signs of inflammation compared with P gingivalis-infected control mice.

CONCLUSIONS

Our study provides evidence that changes in epithelial organisation can exacerbate the effects of P gingivalis infection, with similarities to the most severe forms of human periodontitis.

Regulation of toll-like receptor (TLR) signaling pathways in atherosclerosis: from mechanisms to targeted therapeutics

Atherosclerosis, one of the life-threatening cardiovascular diseases (CVDs), has been demonstrated to be a chronic inflammatory disease, and inflammatory and immune processes are involved in the origin and development of the disease. Toll-like receptors (TLRs), a class of pattern recognition receptors that trigger innate immune responses by identifying pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), regulate numerous acute and chronic inflammatory diseases. Recent studies reveal that TLRs have a vital role in the occurrence and development of atherosclerosis, including the initiation of endothelial dysfunction, interaction of various immune cells, and activation of a number of other inflammatory pathways. We herein summarize some other inflammatory signaling pathways, protein molecules, and cellular responses associated with TLRs, such as NLRP3, Nrf2, PCSK9, autophagy, pyroptosis and necroptosis, which are also involved in the development of AS. Targeting TLRs and their regulated inflammatory events could be a promising new strategy for the treatment of atherosclerotic CVDs. Novel drugs that exert therapeutic effects on AS through TLRs and their related pathways are increasingly being developed. In this article, we comprehensively review the current knowledge of TLR signaling pathways in atherosclerosis and actively seek potential therapeutic strategies using TLRs as a breakthrough point in the prevention and therapy of atherosclerosis.

Interaction between Gut Microbiota and Dendritic Cells in Colorectal Cancer

Colorectal cancer (CRC) is a malignancy that manifests in serial stages and has been observed to have an escalating incidence in modern societies, causing a significant global health problem. The development of CRC is influenced by various exogenous factors, including lifestyle, diet, nutrition, environment, and microbiota, that can affect host cells, including immune cells. Various immune dysfunctions have been recognized in patients with CRC at different stages of this disease. The signature of microbiota in the development of CRC-inflammation related to obesity, diet, and reactive host cells, such as dendritic cells (DCs)-has been highlighted by many studies. This study focuses on DCs, the primary cellular mediators linking innate and adaptive immune responses against cancer. In addition, this review focuses on the role of microbiota in dysbiosis and how it affects DCs and, in turn, the immune response and progression of CRC by stimulating different sets of T cells. Additionally, DCs' role in protecting this delicate balance is examined. This is to determine how gene yields of commensal microbiota may be critical in restoring this balance when disrupted. The stages of the disease and major checkpoints are discussed, as well as the role of the C-type lectin receptor of immature DCs pattern recognition receptor in CRC. Finally, based on a thorough examination of worldwide clinical studies and recent advancements in cancer immunotherapy, it is recommended that innovative approaches that integrate DC vaccination strategies with checkpoint inhibitors be considered. This approach holds great promise for improving CRC management.

Involvement of ferroptosis in Porphyromonas gingivalis lipopolysaccharide-stimulated periodontitis in vitro and in vivo

OBJECTIVES

Ferroptosis is associated with multiple inflammatory diseases. Periodontitis is an inflammatory disease mainly caused by oral opportunistic pathogens. However, the ferroptosis-periodontitis relationship has not been thoroughly described. We here analyzed whether ferroptosis is involved in periodontitis.

MATERIALS AND METHODS

Human gingival fibroblasts (HGFs) were stimulated with P. gingivalis-LPS and ferrostatin-1 (Fer-1, a ferroptosis inhibitor), and changes in mitochondrial morphology, ferroptosis-related factors, and inflammation levels were detected. After the rat experimental periodontitis model was established, changes in ferroptosis-related factors and inflammation levels were re-evaluated in the same manner.

RESULTS

Porphyromonas gingivalis-LPS-induced mitochondrial shrinkage, an increase in mitochondrial membrane density, and upregulation of reactive oxygen species in HGFs. The expression of prostaglandin-endoperoxide synthase 2, transferrin receptor 1, and malondialdehyde and inflammation levels were upregulated, whereas the expression of solute carrier family seven member 11, glutathione peroxidase 4, superoxide dismutase, and glutathione were downregulated. Fer-1 attenuated these aforementioned changes and inflammation levels induced by P. gingivalis-LPS. The in vivo experiment results were consistent with the in vitro experiment results.

CONCLUSIONS

Ferroptosis is involved in inflammatory processes in HGFs upon P. gingivalis-LPS stimulation. Ferroptosis is observed in the gingival tissue of periodontitis rats.

The Immune System Response to Porphyromonas gingivalis in Neurological Diseases

Previous studies have reported an association between oral microbial dysbiosis and the development and progression of pathologies in the central nervous system. Porphyromonas gingivalis (Pg), the keystone pathogen of the oral cavity, can induce a systemic antibody response measured in patients' sera using enzyme-linked immunosorbent assays. The present case-control study quantified the immune system's response to Pg abundance in the oral cavities of patients affected by different central nervous system pathologies. The study cohort included 87 participants: 23 healthy controls (HC), 17 patients with an acute neurological condition (N-AC), 19 patients with a chronic neurological condition (N-CH), and 28 patients with neurodegenerative disease (N-DEG). The results showed that the Pg abundance in the oral cavity was higher in the N-DEG patients than in the HC (p = 0.0001) and N-AC patients (p = 0.01). In addition, the Pg abundance was higher in the N-CH patients than the HCs (p = 0.005). Only the N-CH patients had more serum anti-Pg antibodies than the HC (p = 0.012). The inadequate response of the immune system of the N-DEG group in producing anti-Pg antibodies was also clearly indicated by an analysis of the ratio between the anti-Pg antibodies quantity and the Pg abundance. Indeed, this ratio was significantly lower between the N-DEG group than all other groups (p = 0.0001, p = 0.002, and p = 0.03 for HC, N-AC, and N-CH, respectively). The immune system's response to Pg abundance in the oral cavity showed a stepwise model: the response diminished progressively from the patients affected with an acute condition to the patients suffering from chronic nervous system disorders and finally to the patients affected by neurodegenerative diseases.

Endotoxin of Porphyromonas gingivalis amplifies the inflammatory response in hyperglycemia-induced zebrafish through a mechanism involving chitinase-like protein YKL-40 analogs

Porphyromonas gingivalis (P. gingivalis), a key pathogen in periodontal diseases, is also associated with hyperglycemia-associated systemic diseases, including diabetes mellitus (DM). Gingipains are the most important endotoxins of P. gingivalis, and in vivo studies using gingipains are scarce. Zebrafish (Danio rerio) is a vertebrate with high physiological and genetic homology with humans that has multiple co-orthologs for human genes, including inflammation-related proteins. The aim of our study was to determine the effects of gingipain in a hyperglycemia-induced zebrafish model by evaluating inflammation, oxidant-antioxidant status, and the cholinergic system. Adult zebrafish were grouped into the control group (C), hyperglycemia-induced group subjected to 15 days of overfeeding (OF), gingipain-injected group (GP), and gingipain-injected hyperglycemic group (OF + GP). At the end of 15 days, an oral glucose tolerance test (OGTT) was performed, and fasting blood glucose (FBG) levels were measured. Lipid peroxidation (LPO), nitric oxide (NO), glutathione (GSH), glutathione S-transferase, catalase, acetylcholinesterase (AChE), alkaline phosphatase (ALP), and sialic acid (SA) levels were determined spectrophotometrically in the hepatopancreas. The expression levels of tnf-⍺, il-1β, ins, crp, and the acute phase protein YKL-40 analogs chia.5 and chia.6 were evaluated by RT‒PCR. After two weeks of overfeeding, significantly increased weight gain, FBG, and OGTT confirmed that the zebrafish were hyperglycemic. Increased oxidative stress, inflammation, and AChE and ALP activities were observed in both the overfeeding and GP groups. Amplification of inflammation and oxidative stress was evident in the OF + GP group through increased expression of crp, il-1β, chia.5, and chia.6 and increased LPO and NO levels. Our results support the role of gingipains in the increased inflammatory response in hyperglycemia-associated diseases.

Association between human herpes simplex virus and periodontitis: results from the continuous National Health and Nutrition Examination Survey 2009-2014

BACKGROUND

Periodontitis is a common chronic oral disease which seriously affects people's quality of life. Although human herpes simplex virus (HSV) is also found in periodontal lesions, the association between HSV infection and periodontitis is unclear.

METHODS

The National Health and Nutrition Examination Survey (NHANES) data for 2009-2010, 2011-2012 and 2013-2014 was combined, and the association between HSV infection and periodontitis in the general population and particular subgroups was investigated through weighted multi-logistic analyses.

RESULTS

There were 4,733 participants aged 30-50 years old with clinically assessed periodontitis concurrent with HSV infection. In general analysis, after adjusted for covariates, both HSV-1 (OR = 1.09, P < 0.001) and HSV-2 (OR = 1.06, P = 0.030) infection was significantly associated with periodontitis. In subgroup analyses, compared with patients without HSV infection, patients with HSV-1( +) & HSV-2( +) and HSV-1( +) & HSV-2(-) infection showed higher risk of periodontitis in all subgroups (OR = 1.15, OR = 1.09, P < 0.001), while patients with HSV-1(-) & HSV-2( +) infection showed higher risk of and periodontitis only in the subgroup of people aged 40-50 years (OR = 1.10, P = 0.032) and the Mexican-American subgroup (OR = 1.35, P = 0.042). When only severe periodontitis is considered, HSV infection was associated with periodontitis, no matter the patient was infected with either of the virus or both.

CONCLUSIONS

HSV-1 infection was significantly associated with periodontitis and severe periodontitis, while HSV-2 infection was associated with severe periodontitis, and periodontitis in 40-50-year-olds and Mexican-Americans.

Systematic analysis of prophages carried by Porphyromonas gingivalis

To systematically investigate the prophages carrying in Porphyromonas gingivalis (P. gingivalis) strains, analyze potential antibiotic resistance genes (ARGs) and virulence genes in these prophages. We collected 90 whole genome sequences of P. gingivalis from NCBI and utilized the Prophage Hunter online software to predict prophages; Comprehensive antibiotic research database (CARD) and virulence factors database (VFDB) were adopted to analyze the ARGs and virulence factors (VFs) carried by the prophages. Sixty-nine prophages were identified among 24/90 P. gingivalis strains, including 17 active prophages (18.9%) and 52 ambiguous prophages (57.8%). The proportion of prophages carried by each P. gingivalis genome ranged from 0.5% to 6.7%. A total of 188 antibiotic resistance genes belonging to 25 phenotypes and 46 different families with six mechanisms of antibiotic resistance were identified in the 17 active prophages. Three active prophages encoded 4 virulence genes belonging to type III and type VI secretion systems. The potential hosts of these virulence genes included Escherichia coli, Shigella sonnei, Salmonella typhi, and Klebsiella pneumoniae. In conclusion, 26.7% P. gingivalis strains carry prophages, while the proportion of prophage genes in the P. gingivalis genome is relatively low. In addition, approximately 39.7% of the P. gingivalis prophage genes have ARGs identified, mainly against streptogramin, peptides, and aminoglycosides. Only a few prophages carry virulence genes. Prophages may play an important role in the acquisition, dissemination of antibiotic resistance genes, and pathogenicity evolution in P. gingivalis.