Fusobacterium nucleatum Facilitates Apoptosis, ROS Generation, and Inflammatory Cytokine Production by Activating AKT/MAPK and NF-κB Signaling Pathways in Human Gingival Fibroblasts

Targeted elimination of Fusobacterium nucleatum alleviates periodontitis

Background

Fusobacterium nucleatum, a pathobiont in periodontal disease, contributes to alveolar bone destruction. We assessed the efficacy of a new targeted antimicrobial, FP-100, in eradicating F. nucleatum from the oral microbial community in vitro and in vivo and evaluated its effectiveness in reducing bone loss in a mouse periodontitis model.

Methods

A multispecies bacterial community was cultured and treated with two concentrations of FP-100 over two days. Microbial profiles were examined at 24-h intervals using 16S rRNA sequencing. A ligature-induced periodontitis mouse model was employed to test FP-100 in vivo.

Results

FP-100 significantly reduced Fusobacterium spp. within the in vitro community (p < 0.05) without altering microbial diversity at a 2 μM concentration. In mice, cultivable F. nucleatum was undetectable in FP-100-treated ligatures but persistent in controls. Beta diversity plots showed distinct microbial structures between treated and control mice. Alveolar bone loss was significantly reduced in the FP-100 group (p = 0.018), with concurrent decreases in gingival IL-1β and TNF-α expression (p = 0.052 and 0.018, respectively).

Conclusion

FP-100 effectively eliminates F. nucleatum from oral microbiota and significantly reduces bone loss in a mouse periodontitis model, demonstrating its potential as a targeted therapeutic agent for periodontal disease.

Red-complex bacteria exhibit distinctly different interactions with human periodontal ligament stromal cells compared to Fusobacterium nucleatum

OBJECTIVE

The red-complex bacteria Porphyromonas gingivalis and Tannerella forsythia together with Fusobacterium nucleatum are essential players in periodontitis. This study investigated the bacterial interplay with human periodontal ligament mesenchymal stromal cells (hPDL-MSCs) which act in the acute phase of periodontal infection.

DESIGN

The capability of the bacteria to induce an inflammatory response as well as their viability, cellular adhesion and invasion were analyzed upon mono- and co-infections of hPDL-MSCs to delineate potential synergistic or antagonistic effects. The expression level and concentration of interleukin (IL)-6, IL-8 and monocyte chemoattractant protein (MCP)-1 were measured using qRT-PCR and ELISA. Viability, invasion, and adhesion were determined quantitatively using agar plate culture and qualitatively by confocal microscopy.

RESULTS

Viability of P. gingivalis and T. forsythia but not F. nucleatum was preserved in the presence of hPDL-MSCs, even in an oxygenated environment. F. nucleatum significantly increased the expression and concentration of IL-6, IL-8 and MCP-1 in hPDL-MSCs, while T. forsythia and P. gingivalis caused only a minimal inflammatory response. Co-infections in different combinations had no effect on the inflammatory response. Moreover, P. gingivalis mitigated the increase in cytokine levels elicited by F. nucleatum. Both red-complex bacteria adhered to and invaded hPDL-MSCs in greater numbers than F. nucleatum, with only a minor effect of co-infections.

CONCLUSIONS

Oral bacteria of different pathogenicity status interact differently with hPDL-MSCs. The data support P. gingivalis' capability to manipulate the inflammatory host response. Further research is necessary to obtain a comprehensive picture of the role of hPDL-MSCs in more complex oral biofilms.

Investigating the effect of Fusobacterium nucleatum on the aggressive behavior of cancer-associated fibroblasts in colorectal cancer

Fusobacterium nucleatum, (F. nucleatum) as a known factor in inducing oncogenic, invasive, and inflammatory responses, can lead to an increase in the incidence and progression of colorectal cancer (CRC). Cancer-associated fibroblasts (CAF) are also one of the key components of the tumor microenvironment (TME), which lead to resistance to treatment, metastasis, and disease recurrence with their markers, secretions, and functions. This study aimed to investigate the effect of F. nucleatum on the invasive phenotype and function of fibroblast cells isolated from normal and cancerous colorectal tissue. F. nucleatum bacteria were isolated from deep periodontal pockets and confirmed by various tests. CAF cells from tumor tissue and normal fibroblasts (NF) from a distance of 10 cm of tumor tissue were isolated from 5 patients by the explant method and were exposed to secretions and ghosts of F. nucleatum. The expression level of two markers, fibroblast activation protein (FAP), and α-smooth muscle actin (α-SMA), and the amount of production of two cytokines TGF-β and IL-6 from fibroblast cells were measured by flow cytometry and ELISA test, respectively before and after exposure to different bacterial components. The expression of the FAP marker was significantly higher in CAF cells compared to NF cells (P < 0.05). Also, the expression of IL-6 in CAF cells was higher than that of NF cells. In investigating the effect of bacterial components on the function of fibroblastic cells, after comparing the amount of IL-6 produced between the normal tissue of each patient and his tumoral tissue under 4 treated conditions, it was found that the amount of IL-6 production from the CAF cells of patients in the control group, treated with heat-killed ghosts and treated with paraformaldehyde-fixed ghosts had a significant increase compared to NF cells (P < 0.05). Due to the significant increase in FAP marker expression in fibroblast cells of tumor tissue compared to normal tissue, it seems that FAP can be used as a very good therapeutic marker, especially in patients with high levels of CAF cells. Various components of F. nucleatum could affect fibroblast cells differentially and at least part of the effect of this bacterium in the TME is mediated by CAF cells.

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.

Current status of superoxide dismutase 2 on oral disease progression by supervision of ROS

The recent Global Burden of Disease results have demonstrated that oral diseases are some of the most significant public health challenges facing the world. Owing to its specific localization advantage, superoxide dismutase 2 (SOD2 or MnSOD) has the ability to process the reactive oxygen species (ROS) produced by mitochondrial respiration before anything else, thereby impacting the occurrence and development of diseases. In this review, we summarize the processes of common oral diseases in which SOD2 is involved. SOD2 is upregulated in periodontitis to protect the tissue from the distant damage caused by excessive ROS and further reduce inflammatory progression. SOD2 also participates in the specific pathogenesis of oral cancers and dental diseases. The clinical application prospects of SOD2 in oral diseases will be discussed further, referencing the differences and relationship between oral diseases and other clinical systemic diseases.

About a Possible Impact of Endodontic Infections by Fusobacterium nucleatum or Porphyromonas gingivalis on Oral Carcinogenesis: A Literature Overview

Periodontitis is linked to the onset and progression of oral squamous cell carcinoma (OSCC), an epidemiologically frequent and clinically aggressive malignancy. In this context, Fusobacterium (F.) nucleatum and Porphyromonas (P.) gingivalis, two bacteria that cause periodontitis, are found in OSCC tissues as well as in oral premalignant lesions, where they exert pro-tumorigenic activities. Since the two bacteria are present also in endodontic diseases, playing a role in their pathogenesis, here we analyze the literature searching for information on the impact that endodontic infection by P. gingivalis or F. nucleatum could have on cellular and molecular events involved in oral carcinogenesis. Results from the reviewed papers indicate that infection by P. gingivalis and/or F. nucleatum triggers the production of inflammatory cytokines and growth factors in dental pulp cells or periodontal cells, affecting the survival, proliferation, invasion, and differentiation of OSCC cells. In addition, the two bacteria and the cytokines they induce halt the differentiation and stimulate the proliferation and invasion of stem cells populating the dental pulp or the periodontium. Although most of the literature confutes the possibility that bacteria-induced endodontic inflammatory diseases could impact on oral carcinogenesis, the papers we have analyzed and discussed herein recommend further investigations on this topic.

Fusobacterium nucleatum: An Overview of Evidence, Demi-Decadal Trends, and Its Role in Adverse Pregnancy Outcomes and Various Gynecological Diseases, including Cancers

Gynecological and obstetric infectious diseases are crucial to women's health. There is growing evidence that links the presence of Fusobacterium nucleatum (F. nucleatum), an anaerobic oral commensal and potential periodontal pathogen, to the development and progression of various human diseases, including cancers. While the role of this opportunistic oral pathogen has been extensively studied in colorectal cancer in recent years, research on its epidemiological evidence and mechanistic link to gynecological diseases (GDs) is still ongoing. Thus, the present review, which is the first of its kind, aims to undertake a comprehensive and critical reappraisal of F. nucleatum, including the genetics and mechanistic role in promoting adverse pregnancy outcomes (APOs) and various GDs, including cancers. Additionally, this review discusses new conceptual advances that link the immunomodulatory role of F. nucleatum to the development and progression of breast, ovarian, endometrial, and cervical carcinomas through the activation of various direct and indirect signaling pathways. However, further studies are needed to explore and elucidate the highly dynamic process of host-F. nucleatum interactions and discover new pathways, which will pave the way for the development of better preventive and therapeutic strategies against this pathobiont.

Co-Culture of P. gingivalis and F. nucleatum Synergistically Elevates IL-6 Expression via TLR4 Signaling in Oral Keratinocytes

Periodontitis, characterized by persistent inflammation in the periodontium, is intricately connected to systemic diseases, including oral cancer. Bacteria, such as Porphyromonas gingivalis and Fusobacterium nucleatum, play a pivotal role in periodontitis development because they contribute to dysbiosis and tissue destruction. Thus, comprehending the interplay between these bacteria and their impacts on inflammation holds significant relevance in clinical understanding and treatment advancement. In the present work, we explored, for the first time, their impacts on the expressions of pro-inflammatory mediators after infecting oral keratinocytes (OKs) with a co-culture of pre-incubated P. gingivalis and F. nucleatum. Our results show that the co-culture increases IL-1β, IL-8, and TNF-α expressions, synergistically augments IL-6, and translocates NF-kB to the cell nucleus. These changes in pro-inflammatory mediators-associated with chronic inflammation and cancer-correlate with an increase in cell migration following infection with the co-cultured bacteria or P. gingivalis alone. This effect depends on TLR4 because TLR4 knockdown notably impacts IL-6 expression and cell migration. Our study unveils, for the first time, crucial insights into the outcomes of their co-culture on virulence, unraveling the role of bacterial interactions in polymicrobial diseases and potential links to oral cancer.

Fusobacterium nucleatum dysregulates inflammatory cytokines and NLRP3 inflammasomes in oral cells

OBJECTIVE

This study aimed to clarify the difference in Fusobacterium nucleatum (F. nucleatum) induced inflammatory cytokines and nod-like receptor protein 3 (NLRP3) inflammasomes dysregulation among three periodontal cells.

METHODS

Oral epithelial cells (HIOECs), THP-1 macrophages, and human gingival fibroblasts (HGFs) were exposed to F. nucleatum with/without adenosine triphosphate (ATP) and nigericin (Nig). Cell morphology was assessed by scanning electron microscopy. qRT-PCR, protein microarrays, and bioinformatic methods were used to evaluate the cytokines and their complex interplay. NLRP3 inflammasomes activation was detected by western blotting and ELISA.

RESULTS

F. nucleatum adhered to and invaded cells. In HIOECs, F. nucleatum enhanced interleukin (IL)-1α/1β/6/10/13, TNF-α, and interferon (IFN)-γ expression. In THP-1 macrophages, F. nucleatum up-regulated IL-1α/1β/6/10 and TNF-α levels. In HGFs, F. nucleatum increased IL-6 levels. F. nucleatum and ATP synergistically boosted IFN-γ level in THP-1 macrophages and IL-13 level in HGFs. IL-1α/1β/6, and TNF-α served as epicenters of the inflammatory response. Additionally, F. nucleatum activated NLRP3 inflammasomes in HIOECs, and ATP/Nig boosted the activation. F. nucleatum also triggered NLRP3 inflammasomes in THP-1 macrophages, but in HGFs, only NLRP3 and caspase-1 levels were elevated.

CONCLUSION

F. nucleatum infiltrated periodontal supporting cells and dysregulated inflammatory cytokines and NLRP3 inflammasomes.

Gut Bacteria-derived Membrane Vesicles Induce Colonic Dysplasia by Inducing DNA Damage in Colon Epithelial Cells

BACKGROUND & AIMS

Colorectal cancer (CRC) is the third most common cancer in the world. Gut microbiota has recently been implicated in the development of CRC. Actinomyces odontolyticus is one of the most abundant bacteria in the gut of patients with very early stages of CRC. A odontolyticus is an anaerobic bacterium existing principally in the oral cavity, similar to Fusobacterium nucleatum, which is known as a colon carcinogenic bacterium. Here we newly determined the biological functions of A odontolyticus on colonic oncogenesis.

METHODS

We examined the induction of intracellular signaling by A odontolyticus in human colonic epithelial cells (CECs). DNA damage levels in CECs were confirmed using the human induced pluripotent stem cell-derived gut organoid model and mouse colon tissues in vivo.

RESULTS

A odontolyticus secretes membrane vesicles (MVs), which induce nuclear factor kappa B signaling and also produce excessive reactive oxygen species (ROS) in colon epithelial cells. We found that A odontolyticus secretes lipoteichoic acid-rich MVs, promoting inflammatory signaling via TLR2. Simultaneously, those MVs are internalized into the colon epithelial cells, co-localize with the mitochondria, and cause mitochondrial dysfunction, resulting in excessive ROS production and DNA damage. Induction of excessive DNA damage in colonic cells by A odontolyticus-derived MVs was confirmed in the gut organoid model and also in mouse colon tissues.

CONCLUSIONS

A odontolyticus secretes MVs, which cause chronic inflammation and ROS production in colonic epithelial cells, leading to the initiation of CRC.

Visual analysis of colorectal cancer and gut microbiota: A bibliometric analysis from 2002 to 2022

A growing number of studies have shown that gut microbiota (GM) plays an essential role in the occurrence and development of colorectal cancer (CRC). The current body of research exploring the relationship between CRC and GM is vast. Nevertheless, bibliometric studies in this area have not yet been reported. This study aimed to explore the hotspots and frontiers of research on GM and CRC in the past 20 years, which may provide a reference for researchers in this field. The Web of Science Core Collection database was searched for publications on CRC and GM from 2002 to 2022. The scientometric softwares CiteSpace and VOSviewer were used to visually analyze the countries, institutions, authors, journals, and keywords involved in the literature. Keywords co-occurrence, cluster, and burst analysis were utilized to further explore the current state and development trends of research on GM and CRC. A total of 2158 publications were included in this study, with a noticeably rising annual publication trend. The majority of these papers are from 80 nations, primarily China and the USA. J Yu was the most active author and WS Garrett has the highest citation. Among all institutions, Shanghai Jiao Tong University has the largest number of papers. Most of the publications were published in the International Journal of Molecular Sciences, with Science being the most frequently cited journal. The 4 main clusters mainly involved probiotics, inflammation, molecular mechanisms, and research methods. Current research hotspots included "Fusobacterium nucleatum," "Escherichia coli," etc. Newly emerging research has focused predominantly on immune response, gene expression, and recent strategies for the treatment of CRC with GM. The relationship between GM and CRC will continue to be a hot research area. Changes in the composition of GM in patients with CRC, the potential molecular mechanisms as well as probiotics and natural products used in the treatment of CRC have been the focus of current research and hotspots for future studies.

HIF-1α and periodontitis: Novel insights linking host-environment interplay to periodontal phenotypes

Periodontitis, the sixth most prevalent epidemic disease globally, profoundly impacts oral aesthetics and masticatory functionality. Hypoxia-inducible factor-1α (HIF-1α), an oxygen-dependent transcriptional activator, has emerged as a pivotal regulator in periodontal tissue and alveolar bone metabolism, exerts critical functions in angiogenesis, erythropoiesis, energy metabolism, and cell fate determination. Numerous essential phenotypes regulated by HIF are intricately associated with bone metabolism in periodontal tissues. Extensive investigations have highlighted the central role of HIF and its downstream target genes and pathways in the coupling of angiogenesis and osteogenesis. Within this concise perspective, we comprehensively review the cellular phenotypic alterations and microenvironmental dynamics linking HIF to periodontitis. We analyze current research on the HIF pathway, elucidating its impact on bone repair and regeneration, while unraveling the involved cellular and molecular mechanisms. Furthermore, we briefly discuss the potential application of targeted interventions aimed at HIF in the field of bone tissue regeneration engineering. This review expands our biological understanding of the intricate relationship between the HIF gene and bone angiogenesis in periodontitis and offers valuable insights for the development of innovative therapies to expedite bone repair and regeneration.

Fusobacterium nucleatum infection activates the noncanonical inflammasome and exacerbates inflammatory response in DSS-induced colitis

Caspase activation results in pyroptosis, an inflammatory cell death that contributes to several inflammatory diseases by releasing inflammatory cytokines and cellular contents. Fusobacterium nucleatum is a periodontal pathogen frequently detected in human cancer and inflammatory bowel diseases. Studies have reported that F. nucleatum infection leads to NLRP3 activation and pyroptosis, but the precise activation process and disease association remain poorly understood. This study demonstrated that F. nucleatum infection exacerbates acute colitis in mice and activates pyroptosis through caspase-11-mediated gasdermin D cleavage in macrophages. Furthermore, F. nucleatum infection in colitis mice induces the enhancement of IL-1⍺ secretion from the colon, affecting weight loss and severe disease activities. Neutralization of IL-1⍺ protects F. nucleatum infected mice from severe colitis. Therefore, F. nucleatum infection facilitates inflammation in acute colitis with IL-1⍺ from colon tissue by activating noncanonical inflammasome through gasdermin D cleavage.

Links between oral microbiome and insulin resistance: Involvement of MAP kinase signaling pathway

Oral dysbiosis contributes to periodontitis and has implications for systemic diseases. Diabetes mellitus is a common metabolic disorder characterized by impaired glucose regulation. AMP-activated protein kinase (AMPK) plays a vital role in regulating glucose uptake and glycogenesis in the liver. This study aimed to investigate the association between periodontal bacteria and diabetes mellitus. A clinical trial was conducted to explore the association between oral bacteria and hyperglycemia. Additionally, we elucidated the molecular mechanisms by which periodontal bacteria cause insulin resistance. In the clinical trial, we discovered significant alterations in the expression levels of Fusobacterium nucleatum (Fn) and Tannerella forsythia (Tf) in patients with diabetes compared with healthy controls. Furthermore, Fn and Tf levels positively correlated with fasting blood glucose and glycated hemoglobin (HbA1C) levels. Moreover, we explored and elucidated the molecular mechanism by which Fusobacterium nucleatum culture filtrate (FNCF) induces cytokine release via the Toll-like receptor 2 (TLR2) signaling pathway in human gingival epithelial Smulow-Glickman (S-G) cells. This study investigated the effects of cytokines on insulin resistance pathways in liver cells. The use of an extracellular signal-regulated kinase (ERK) inhibitor (U0126) demonstrated that FNCF regulates the insulin receptor substrate 1 and protein kinase B (IRS1/AKT) signaling pathway, which affects key proteins involved in hepatic glycogen synthesis, including glycogen synthase kinase-3 beta (GSK3β) and glycogen synthase (GS), ultimately leading to insulin resistance. These findings suggest that ERK plays a crucial role in hepatocyte insulin resistance.

Gut microbiota in adults with moyamoya disease: characteristics and biomarker identification

Background and purpose

When it comes to the onset of moyamoya disease (MMD), environmental variables are crucial. Furthermore, there is confusion about the relationship between the gut microbiome, an environmental variable, and MMD. Consequently, to identify the particular bacteria that cause MMD, we examined the gut microbiome of MMD individuals and healthy controls (HC).

Methods

A prospective case-control investigation was performed from June 2021 to May 2022. The fecal samples of patients with MMD and HC were obtained. Typically, 16S rRNA sequencing was employed to examine their gut microbiota. The QIIME and R softwares were used to examine the data. The linear discriminant analysis effect size analysis was used to determine biomarkers. Multivariate analysis by linear models (MaAsLin)2 were used to find associations between microbiome data and clinical variables. Model performance was assessed using the receiver operating characteristic curve and the decision curve analysis.

Results

This investigation involved a total of 60 MMD patients and 60 HC. The MMD group's Shannon and Chao 1 indices were substantially lower than those of the HC cohort. β-diversity was significantly different in the weighted UniFrac distances. At the phylum level, the relative abundance of Fusobacteriota/Actinobacteria was significantly higher/lower in the MMD group than that in the HC group. By MaAsLin2 analysis, the relative abundance of the 2 genera, Lachnoclostridium and Fusobacterium, increased in the MMD group, while the relative abundance of the 2 genera, Bifidobacterium and Enterobacter decreased in the MMD group. A predictive model was constructed by using these 4 genera. The area under the receiver operating characteristic curve was 0.921. The decision curve analysis indicated that the model had usefulness in clinical practice.

Conclusions

The gut microbiota was altered in individuals with MMD, and was characterized by increased abundance of Lachnoclostridium and Fusobacterium and decreased abundance of Bifidobacterium and Enterobacter. These 4 genera could be used as biomarkers and predictors in clinical practice.

N-Acetyl-l-cysteine-Derived Carbonized Polymer Dots with ROS Scavenging via Keap1-Nrf2 Pathway Regulate Alveolar Bone Homeostasis in Periodontitis

Periodontitis is a type of chronic inflammatory oral disease characterized by the destruction of periodontal connective tissue and progressive alveolar bone resorption. As oxidative stress is the key cause of periodontitis in the early periodontal microenvironment, antioxidative therapy has been considered a viable treatment for periodontitis. However, more stable and effective reactive oxygen species (ROS)-scavenging nanomedicines are still highly needed due to the instability of traditional antioxidants. Herein, a new type of N-acetyl-l-cysteine (NAC)-derived red fluorescent carbonized polymer dots (CPDs) has been synthesized with excellent biocompatibility, which can serve as an extracellular antioxidant to scavenge ROS effectively. Moreover, NAC-CPDs can promote osteogenic differentiation in human periodontal ligament cells (hPDLCs) under H2 O2 stimulation. In addition, NAC-CPDs are capable of targeted accumulation in alveolar bone in vivo, reducing the level of alveolar bone resorption in periodontitis mice, as well as performing fluorescence imaging in vitro and in vivo. In terms of mechanism, NAC-CPDs may regulate redox homeostasis and promote bone formation in the periodontitis microenvironment by modulating the kelch-like ECH-associated protein l (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. This study provides a new strategy for the application of CPDs theranostic nanoplatform for periodontitis.

Research on the Association Between Periodontitis and COPD

Periodontitis is a common chronic bacteria-initiated inflammatory disease that is closely associated with various systemic diseases, including chronic obstructive pulmonary disease (COPD). Periodontitis and COPD share similar risk factors, pathology and microorganisms. Epidemiological and clinical research have shown positive correlation between the two diseases. Individuals with severe periodontitis had a higher risk of developing COPD. Moreover, the relative risk of COPD in severe periodontitis was much higher compared to people without periodontal disease and patients with mild to moderate periodontitis. COPD patients with periodontitis had a higher frequency of COPD exacerbation and periodontal treatment demonstrated some control of COPD. However, the nature of periodontitis affecting COPD still needs further exploration. Periodontitis caused microbial and immune imbalances of the lung through several aspects: (I) under periodontitis status, periodontal pathogens directly caused the lung inflammatory reaction after inhalation and colonization on the lung, (II) periodontitis status promoted the oral colonization of pneumonia-associated pathogens, (III) periodontitis status affected the respiratory epithelium structure and (IV) periodontitis status caused imbalances in neutrophils, macrophages and inflammatory cytokines. In this review, we conclude the association between periodontitis and COPD through several aspects and further discuss the potential mechanism by which periodontitis affects COPD.

Modeling periodontal host-microbe interactions using vascularized gingival connective tissue equivalents

Gingival connective tissue and its vasculature play a crucial role in the host's immune response against the periodontal microbiome and serve as a bridge between the oral and systemic environments. However, there is a lack of representative models that mimic the complex features of vascularized gingival connective tissue and its interaction with the periodontal microbiome, hindering our understanding of periodontal health and disease. Towards this pursuit, we present the characterization of vascularized gingival connective tissue equivalents (CTEs) as a model to study the interactions between oral biofilm colonizers and gingival tissues in healthy and diseased states. Whole-mount immunolabeling and label-free confocal reflectance microscopy of human fibrin-based matrix embedded with gingival fibroblasts and microvascular endothelial cells demonstrated the generation of bi-cellular vascularized gingival CTEs. Next, we investigated the response of the vascularized gingival CTEs to early, intermediate, and late oral biofilm colonizers. Despite colonization, the early colonizers did not elicit any significant change in the production of the cytokines and chemokines by the CTEs representative of the commensal and homeostatic state. In contrast, intermediate and late colonizers representing a transition to a diseased state exhibited connective tissue and vascular invasion, and elicited a differential immune response accompanied by increased monocyte migration. The culture supernatants produced by the vascularized gingival CTEs in response to early and intermediate colonizers polarized macrophages towards an immunomodulatory M2-like phenotype which activates and protects the host, while the late colonizers polarized towards a pro-inflammatory M1-like phenotype. Lastly,in silicoanalysis showed a high strength of associations between the proteins and transcripts investigated with periodontitis and vascular diseases. In conclusion, the vascularized gingival CTEs provide a biomimeticin vitroplatform to study host-microbiome interactions and innate immune response in periodontal health and diseased states, which potentially paves the way toward the development and assessment of novel periodontal therapeutics.

Fusobacterium nucleatum: a novel immune modulator in breast cancer?

Breast cancer was the most commonly diagnosed cancer worldwide in 2020. Greater understanding of the factors which promote tumour progression, metastatic development and therapeutic resistance is needed. In recent years, a distinct microbiome has been detected in the breast, a site previously thought to be sterile. Here, we review the clinical and molecular relevance of the oral anaerobic bacterium Fusobacterium nucleatum in breast cancer. F. nucleatum is enriched in breast tumour tissue compared with matched healthy tissue and has been shown to promote mammary tumour growth and metastatic progression in mouse models. Current literature suggests that F. nucleatum modulates immune escape and inflammation within the tissue microenvironment, two well-defined hallmarks of cancer. Furthermore, the microbiome, and F. nucleatum specifically, has been shown to affect patient response to therapy including immune checkpoint inhibitors. These findings highlight areas of future research needed to better understand the influence of F. nucleatum in the development and treatment of breast cancer.

Combined Ferromagnetic Nanoparticles for Effective Periodontal Biofilm Eradication in Rat Model

Introduction

The critical challenge for periodontitis therapy is thoroughly eliminating the dental plaque biofilm, particularly penetrating the deep periodontal tissue. Regular therapeutic strategies are insufficient to penetrate the plaque without disturbing the commensal microflora of the oral cavity. Here, we constructed a Fe₃O₄ magnetic nanoparticle loading minocycline (FPM NPs) to penetrate the biofilm physically and effectively eliminate periodontal biofilm.

Methods

In order to penetrate and remove the biofilm effectively, Fe₃O₄ magnetic nanoparticles were modified with minocycline using a co-precipitation method. The particle size and dispersion of the nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. The antibacterial effects were examined to verify the magnetic targeting of FPM NPs. Confocal laser scanning microscopy was employed to check the effect of FPM + MF and develop the best FPM NPs treatment strategy. Additionally, the therapeutic effect of FPM NPs was investigated in periodontitis rat models. The expression of IL-1β, IL-6, and TNF-α in periodontal tissues was measured by qRT-PCR and Western blot.

Results

The multifunctional nanoparticles exhibited intense anti-biofilm activity and good biocompatibility. The magnetic forces could pull FMP NPs against the biofilm mass and kill bacteria deep in the biofilms both in vivo and in vitro. The integrity of the bacterial biofilm is disrupted under the motivation of the magnetic field, allowing for improved drug penetration and antibacterial performance. The periodontal inflammation recovered well after FPM NPs treatment in rat models. Furthermore, FPM NPs could be monitored in real-time and have magnetic targeting potentials.

Conclusion

FPM NPs exhibit good chemical stability and biocompatibility. The novel nanoparticle presents a new approach for treating periodontitis and provides experimental support for using magnetic-targeted nanoparticles in clinic applications.

Fusobacterium nucleatum stimulates cell proliferation and promotes PD-L1 expression via IFIT1-related signal in colorectal cancer

Fusobacterium nucleatum (F. nucleatum) is enriched in colorectal cancer (CRC) tissues and a high amount of F. nucleatum was associated with an immunosuppressive tumor environment. PD-L1 is an important immune checkpoint expressed on tumor cells and promotes tumor immune escape. Whether PD-L1 is regulated by F. nucleatum is still unclear. We demonstrated that F. nucleatum promoted CRC progression and upregulated PD-L1 protein expression in CRC cell lines. Combined m⁶A-seq and RNA-seq identified m⁶A-modified IFIT1 mediating F. nucleatum induced PD-L1 upregulation. IFIT1 mRNA was modified with m⁶A modifications in 3'UTR and the m⁶A levels were altered by F. nucleatum treatment. Our results also indicated that IFIT1 served as a potential oncogene in CRC and regulated PD-L1 protein levels through altering PD-L1 ubiquitination. Clinical CRC data confirmed the correlation among F. nucleatum abundance, IFIT1 and PD-L1 expressions. Our work highlighted the function of F. nucleatum in stimulating PD-L1 expression through m⁶A-modified IFIT1 and provided new aspects for understanding F. nucleatum mediated immune escape.

Antibiofilm activity of ultra-small gold nanoclusters against Fusobacterium nucleatum in dental plaque biofilms

Pathogenic dental plaque biofilms are universal and harmful, which can result in oral infections and systemic diseases. Many conventional therapeutic methods have proven insufficient or ineffective against plaque biofilms. Therefore, new strategies are urgently needed. Fusobacterium nucleatum (F. nucleatum), a periodontal pathogen associated with a variety of oral and systemic diseases, is thought to be central to the development and structure of dental plaques. Here, ultra-small gold nanoclusters (AuNCs) were prepared. They exhibited potent antibacterial activity against F. nucleatum through enhanced destruction of bacterial membranes and generation of reactive oxygen species. Furthermore, due to their excellent penetration, the AuNCs could inhibit biofilm formation and destroy mature biofilms in vitro. Their antibiofilm efficacy was further confirmed in a mouse model, where they reduced biofilm accumulation and ameliorated inflammation. Meanwhile, the disruption of oral and gut microbiota caused by colonization of oral F. nucleatum could be partially restored through AuNCs treatment. Therefore, AuNCs could be considered as promising antibiofilm agents and have great potential in the clinical treatment of dental plaque.

An injectable multifunctional thermo-sensitive chitosan-based hydrogel for periodontitis therapy

Bacteria are recognized as the driving factors of periodontitis. However, excessive reactive oxygen species (ROS) can harm periodontal tissue while also causing an uncontrolled inflammatory response. Hence, eliminating excessive ROS and blocking ROS-induced abnormal inflammatory response by antioxidants are achieving remarkable results in periodontitis therapy. Moreover, influenced by the deep and irregular periodontal pockets, injectable thermo-sensitive chitosan-based hydrogels have attracted a lot of attention. This study aimed to formulate an antibacterial and antioxidant therapeutic regimen by incorporating antimicrobial peptides (Nal-P-113) and/or antioxidants (polydopamine nanoparticles, PDNPs) into chitosan-based hydrogels. The hydrogel was characterized in vitro and finally examined in rats using the experimental periodontitis model. The release kinetics showed that the hydrogel could stably release Nal-P-113 and PDNPs for up to 13 days. The scavenging activity of the hydrogel against DPPH was about 80 % and the antibacterial ratio against Streptococcus gordonii (S. gordonii), Fusobacterium nucleatum (F. nucleatum) and Porphyromonas gingivalis (P. gingivalis) was about 99 %. Importantly, it was examined that the hydrogel had the ability to prevent periodontal tissue damage. Thus, chitosan-based hydrogels may provide a basis for designing multifunctional local drug delivery biomaterials for the treatment of periodontitis.

Canavalia gladiata Pod Extract Mitigates Ovalbumin-Induced Asthma Onset in Male BALB/c Mice via Suppression of MAPK

Asthma is one of the most common inflammatory diseases of the lung worldwide. There has been considerable progress in recent studies to treat and prevent allergic asthma, however, various side effects are still observed in clinical practice. Six-week-old male BALB/c mice were orally administered with either sword bean pod extracts (SBP; 100 or 300 mg/kg) or dexamethasone (DEX; 5 mg/kg) once daily over 3 weeks, followed by ovalbumin sensitization (OVA/Alum.; intraperitoneal administration, 50 μg/2 mg/per mouse). Scoring of lung inflammation was performed to observe pathological changes in response to SBP treatment compared to OVA/Alum.-induced lung injury. Additionally, inflammatory cytokines were quantified in serum, bronchoalveolar lavage fluid (BALF), and lung tissue using ELISA and Western blot analyses. SBP treatment significantly reduced the infiltration of inflammatory cells, and release of histamine, immunoglobulin E, and leukotriene in serum and BALF. Moreover, the therapeutic effect of SBP was also assessed to analyze the inflammatory changes in the lung tissues. SBP markedly suppressed the activation of the MAPK signaling pathway and the expression of key inflammatory proteins (e.g., TNF-α) and Th2 type cytokines (IL-5 and IL-13). SBP was effective in ameliorating the allergic inflammation against OVA/Alum.-induced asthma by suppressing pulmonary inflammation.

The multifaceted role of STAT3 pathway and its implication as a potential therapeutic target in oral cancer

Oral cancer is one of the leading causes of cancer-related deaths, and it has become a matter of serious concern due to the alarming rise in its incidence rate worldwide. Despite recent advancements in oral cancer treatment strategies, there are no significant improvements in patient's survival rate. Among the numerous cell signaling pathways involved in oral cancer development and progression, STAT3 is known to play a multifaceted oncogenic role in shaping the tumor pathophysiology. STAT3 hyperactivation in oral cancer contributes to survival, proliferation, invasion, epithelial to mesenchymal transition, metastasis, immunosuppression, chemoresistance, and poor prognosis. A plethora of pre-clinical and clinical studies have documented the role of STAT3 in the initiation and development of oral cancer and showed that STAT3 inhibition holds significant potential in the prevention and treatment of this cancer. However, to date, targeting STAT3 activation mainly involves inhibiting the upstream signaling molecules such as JAK and IL-6 receptors. The major challenge in targeting STAT3 lies in the complexity of its phosphorylation- and dimerization-independent functions, which are not affected by disrupting the upstream regulators. The present review delineates the significance of the STAT3 pathway in regulating various hallmarks of oral cancer. In addition, it highlights the STAT3 inhibitors identified to date through various preclinical and clinical studies that can be employed for the therapeutic intervention in oral cancer treatment.

Salivary Fusobacterium nucleatum serves as a potential biomarker for colorectal cancer

Fusobacterium nucleatum (Fn) is primarily colonized in the oral cavity. Recently, Fn has been closely associated with the tumorigenesis of colorectal cancer (CRC). Here, we showed that the relative level of Fn DNA was increased in the saliva of the CRC group compared with the normal colonoscopy, hyperplastic polyp, and adenoma groups. Receiver operating characteristic curve analysis illustrated that Fn DNA was superior to carcinoembryonic antigen and carbohydrate antigen 19-9 in CRC diagnosis. Moreover, levels of Fn DNA were associated with the overall survival and disease-free survival of CRC patients, which was an independent factor for prognostic prediction. Transcriptome sequencing identified 1,287 differentially expressed mRNAs in tumor tissues between CRC patients with high-Fn and low-Fn infection. Kyoto encyclopedia of genes and genomes analysis showed that ECM-receptor interaction and focal adhesion were the top two significant pathways. Overall, salivary Fn DNA may be a noninvasive diagnostic and prognostic biomarker for CRC patients.

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Fusobacterium nucleatum DNA level is increased in saliva of colorectal cancer patients

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Salivary F. nucleatum DNA is a biomarker for colorectal cancer diagnosis

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Salivary F. nucleatum DNA is an independent prognostic factor

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KEGG identified relationships to ECM-receptor interaction and focal adhesion pathways

Outer Membrane Vesicles From Fusobacterium nucleatum Switch M0-Like Macrophages Toward the M1 Phenotype to Destroy Periodontal Tissues in Mice

Periodontitis is a chronic inflammatory oral disease that affects nearly 50% of all adults. Fusobacterium nucleatum (F. nucleatum) is known to be involved in the formation and development of periodontitis. Outer membrane vesicles (OMVs) harboring toxic bacterial components are continuously released during F. nucleatum growth and regulate the extent of the inflammatory response by controlling the functions of immune and non-immune cells in tissues. Macrophages are important immune cells in periodontal tissue that resist pathogen invasion and play an important role in the pathophysiological process of periodontitis. However, the role of the interaction between F. nucleatum OMVs and macrophages in the occurrence and development of periodontitis has not been studied. The purpose of this study was to clarify the effect of F. nucleatum OMVs on the polarization of macrophages and the roles of this specific polarization and F. nucleatum OMVs in the pathophysiology of periodontitis. The periodontitis model was established by inducing ligation in C57BL/6 mice as previously described. Micro-CT, RT-qPCR, hematoxylin-eosin (H&E) and tartrate acid phosphatase (TRAP) staining assays were performed to analyze the periodontal tissue, alveolar bone loss, number of osteoclasts and expression of inflammatory factors in gingival tissue. The changes in the state and cytokine secretion of bone marrow-derived macrophages (BMDMs) stimulated by F. nucleatum OMVs were observed in vivo by confocal microscopy, flow cytometry, Western blot and ELISA. Mouse gingival fibroblasts (MGFs) were isolated and then cocultured with macrophages. The effects of F. nucleatum OMVs on the proliferation and apoptosis of MGFs were analyzed by flow cytometry and lactate dehydrogenase (LDH) assays. The periodontitis symptoms of mice in the F. nucleatum OMVs + ligation group were more serious than those of mice in the simple ligation group, with more osteoclasts and more inflammatory factors (IL-1β, IL-6, and TNF-α) being observed in their gingival tissues. M0 macrophages transformed into M1 macrophages after the stimulation of BMDMs with F. nucleatum OMVs, and the M1 macrophages then released more inflammatory cytokines. Analysis of the coculture model showed that the MGF apoptosis and LDH release in the inflammatory environment were increased by F. nucleatum OMV treatment. In conclusion, F. nucleatum OMVs were shown to aggravate periodontitis, alveolar bone loss and the number of osteoclasts in an animal model of periodontitis. F. nucleatum OMVs promoted the polarization of macrophages toward the proinflammatory M1 phenotype, and the inflammatory environment further aggravated the toxicity of F. nucleatum OMVs on MGFs. These results suggest that M1 macrophages and F. nucleatum OMVs play roles in the occurrence and development of periodontitis.

Pathogenic Mechanisms of Fusobacterium nucleatum on Oral Epithelial Cells

Periodontitis is an oral chronic inflammatory disease and may cause tooth loss in adults. Oral epithelial cells provide a barrier for bacteria and participate in the immune response. Fusobacterium nucleatum (F. nucleatum) is one of the common inhabitants of the oral cavity and has been identified as a potential etiologic bacterial agent of oral diseases, such as periodontitis and oral carcinomas. F. nucleatum has been shown to be of importance in the development of diverse human cancers. In the dental biofilm, it exhibits a structural role as a bridging organism, connecting primary colonizers to the largely anaerobic secondary colonizers. It expresses adhesins and is able to induce host cell responses, including the upregulation of defensins and the release of chemokines and interleukins. Like other microorganisms, its detection is achieved through germline-encoded pattern-recognition receptors (PRRs) and pathogen-associated molecular patterns (PAMPs). By identification of the pathogenic mechanisms of F. nucleatum it will be possible to develop effective methods for the diagnosis, prevention, and treatment of diseases in which a F. nucleatum infection is involved. This review summarizes the recent progress in research targeting F. nucleatum and its impact on oral epithelial cells.

Bacteria-Mediated Oncogenesis and the Underlying Molecular Intricacies: What We Know So Far

Cancers are known to have multifactorial etiology. Certain bacteria and viruses are proven carcinogens. Lately, there has been in-depth research investigating carcinogenic capabilities of some bacteria. Reports indicate that chronic inflammation and harmful bacterial metabolites to be strong promoters of neoplasticity. Helicobacter pylori-induced gastric adenocarcinoma is the best illustration of the chronic inflammation paradigm of oncogenesis. Chronic inflammation, which produces excessive reactive oxygen species (ROS) is hypothesized to cause cancerous cell proliferation. Other possible bacteria-dependent mechanisms and virulence factors have also been suspected of playing a vital role in the bacteria-induced-cancer(s). Numerous attempts have been made to explore and establish the possible relationship between the two. With the growing concerns on anti-microbial resistance and over-dependence of mankind on antibiotics to treat bacterial infections, it must be deemed critical to understand and identify carcinogenic bacteria, to establish their role in causing cancer.

Fusobacterium nucleatum Promotes Colorectal Cancer Cell to Acquire Stem Cell-Like Features by Manipulating Lipid Droplet-Mediated Numb Degradation

Fusobacterium nucleatum is a critical microbe that contributes to colorectal cancer progression and chemoresistance. However, whether and how F. nucleatum regulates colorectal cancer stem-like cells (CCSCs) remains unknown. Here, the authors show that F. nucleatum promotes CCSC self-renewal, and non-CCSCs to acquire CCSC features by manipulating cellular lipid accumulation. F. nucleatum infection decreases lipid accumulation in CCSCs by enhancing fatty acid oxidation, thus promoting CCSC self-renewal. In contrast, F. nucleatum increases lipid accumulation in non-CCSCs by promoting fatty acid formation. Lipids are deposited as lipid droplets, which recruits Numb, a key cell fate regulator, through the AP2A/ACSL3 complex, and MDM2, an E3 ubiquitin ligase, though VCP and UBXD8. On lipid droplets, Numb is degraded by MDM2, activating Notch signaling, thus promoting gain of stem-like cell features. Their findings demonstrate that F. nucleatum directly manipulates colorectal cancer cell fate and reveal the mechanism of lipid droplet-mediated Numb degradation for activating Notch signaling.

Effect of Bacterial Infection on Ghrelin Receptor Regulation in Periodontal Cells and Tissues

The effect of bacterial infection on the expression of growth hormone secretagogue receptor (GHS-R) was investigated in periodontal cells and tissues, and the actions of ghrelin were evaluated. GHS-R was assessed in periodontal tissues of rats with and without periodontitis. Human gingival fibroblasts (HGFs) were exposed to Fusobacterium nucleatum in the presence and absence of ghrelin. GHS-R expression was determined by real-time PCR and immunocytochemistry. Furthermore, wound healing, cell viability, proliferation, and migration were evaluated. GHS-R expression was significantly higher at periodontitis sites as compared to healthy sites in rat tissues. F. nucleatum significantly increased the GHS-R expression and protein level in HGFs. Moreover, ghrelin significantly abrogated the stimulatory effects of F. nucleatum on CCL2 and IL-6 expressions in HGFs and did not affect cell viability and proliferation significantly. Ghrelin stimulated while F. nucleatum decreased wound closure, probably due to reduced cell migration. Our results show original evidence that bacterial infection upregulates GHS-R in rat periodontal tissues and HGFs. Moreover, our study shows that ghrelin inhibited the proinflammatory actions of F. nucleatum on HGFs without interfering with cell viability and proliferation, suggesting that ghrelin and its receptor may act as a protective molecule during bacterial infection on periodontal cells.

Fusobacterium nucleatum: The Opportunistic Pathogen of Periodontal and Peri-Implant Diseases

Peri-implant diseases are considered to be a chronic destructive inflammatory destruction/damage occurring in soft and hard peri-implant tissues during the patient’s perennial use after implant restoration and have attracted much attention because of their high incidence. Although most studies seem to suggest that the pathogenesis of peri-implant diseases is similar to that of periodontal diseases and that both begin with microbial infection, the specific mechanism of peri-implant diseases remains unclear. As an oral opportunistic pathogen, Fusobacterium nucleatum (F. nucleatum) has been demonstrated to be vital for the occurrence and development of many oral infectious diseases, especially periodontal diseases. More notably, the latest relevant studies suggest that F. nucleatum may contribute to the occurrence and development of peri-implant diseases. Considering the close connection between peri-implant diseases and periodontal diseases, a summary of the role of Fusobacterium nucleatum in periodontal diseases may provide more research directions and ideas for the peri-implantation mechanism. In this review, we summarize the effects of F. nucleatum on periodontal diseases by biofilm formation, host infection, and host response, and then we establish the relationship between periodontal and peri-implant diseases. Based on the above aspects, we discuss the importance and potential value of F. nucleatum in peri-implant diseases.

More Than Just a Periodontal Pathogen –the Research Progress on Fusobacterium nucleatum

Fusobacterium nucleatum is a common oral opportunistic bacterium that can cause different infections. In recent years, studies have shown that F. nucleatum is enriched in lesions in periodontal diseases, halitosis, dental pulp infection, oral cancer, and systemic diseases. Hence, it can promote the development and/or progression of these conditions. The current study aimed to assess research progress in the epidemiological evidence, possible pathogenic mechanisms, and treatment methods of F. nucleatum in oral and systemic diseases. Novel viewpoints obtained in recent studies can provide knowledge about the role of F. nucleatum in hosts and a basis for identifying new methods for the diagnosis and treatment of F. nucleatum-related diseases.

Role of Hydrogen Sulfide in Oral Disease

Oral diseases are among the most common human diseases yet less studied. These diseases affect both the physical, mental, and social health of the patients resulting in poor quality of life. They affect all ages, although severe stages are mostly observed in older individuals. Poor oral hygiene, genetics, and environmental factors contribute enormously to the development and progression of these diseases. Although there are available treatment options for these diseases, the recurrence of the diseases hinders their efficiency. Oral volatile sulfur compounds (VSCs) are highly produced in oral cavity as a result of bacteria activities. Together with bacteria components such as lipopolysaccharides, VSCs participate in the progression of oral diseases by regulating cellular activities and interfering with the immune response. Hydrogen sulfide (H2S) is a gaseous neurotransmitter primarily produced endogenously and is involved in the regulation of cellular activities. The gas is also among the VSCs produced by oral bacteria. In numerous diseases, H2S have been reported to have dual effects depending on the cell, concentration, and donor used. In oral diseases, high production and subsequent utilization of this gas have been reported. Also, this high production is associated with the progression of oral diseases. In this review, we will discuss the production of H2S in oral cavity, its interaction with cellular activities, and most importantly its role in oral diseases.

Extracellular vesicles of Fusobacterium nucleatum compromise intestinal barrier through targeting RIPK1-mediated cell death pathway

Microbial factors that mediate microbes-host interaction in ulcerative colitis (UC), a chronic disease seriously affecting human health, are not fully known. The emerging oncobacterium Fusobacterium nucleatum (Fn) secretes extracellular vesicles carrying several types of harmful molecules in the intestine which can alter microbes-host interaction, especially the epithelial homeostasis in UC. However, the mechanism is not yet clear. Previously, we isolated EVs by the ultracentrifugation of Fn culture media and characterized them as the potent inducer of pro-inflammatory cytokines. Here, we examined the mechanism in detail. We found that in macrophage/Caco-2 co-cultures, FnEVs significantly promoted epithelial barrier loss and oxidative stress damage, which are related to epithelial necroptosis caused by the activation of receptor-interacting protein kinase 1 (RIPK1) and receptor-interacting protein kinase 3 (RIPK3). Furthermore, FnEVs promoted the migration of RIPK1 and RIPK3 into necrosome in Caco2 cells. Notably, these effects were reversed by TNF-α neutralizing antibody or Necrostatin-1 (Nec-1), a RIPK1 inhibitor. This suggested that FADD-RIPK1-caspase-3 signaling is involved in the process. Moreover, the observed effects were verified in the murine colitis model treated with FnEVs or by adoptive transfer of FnEVs-trained macrophages. In conclusion, we propose that RIPK1-mediated epithelial cell death promotes FnEVs-induced gut barrier disruption in UC and the findings can be used as the basis to further investigate this disease.

Fusobacterium nucleatum and oral cancer: a critical review

There is a growing level of interest in the potential role inflammation has on the initiation and progression of malignancy. Notable examples include Helicobacter pylori-mediated inflammation in gastric cancer and more recently Fusobacterium nucleatum-mediated inflammation in colorectal cancer. Fusobacterium nucleatum is a Gram-negative anaerobic bacterium that was first isolated from the oral cavity and identified as a periodontal pathogen. Biofilms on oral squamous cell carcinomas are enriched with anaerobic periodontal pathogens, including F. nucleatum, which has prompted hypotheses that this bacterium could contribute to oral cancer development. Recent studies have demonstrated that F. nucleatum can promote cancer by several mechanisms; activation of cell proliferation, promotion of cellular invasion, induction of chronic inflammation and immune evasion. This review provides an update on the association between F. nucleatum and oral carcinogenesis, and provides insights into the possible mechanisms underlying it.

Modulation of the Host Cell Transcriptome and Epigenome by Fusobacterium nucleatum

Fusobacterium nucleatum is a ubiquitous opportunistic pathogen with an emerging role as an oncomicrobe in colorectal cancer and other cancer settings. F. nucleatum can adhere to and invade host cells in a manner that varies across F. nucleatum strains and host cell phenotypes. Here, we performed pairwise cocultures between three F. nucleatum strains and two immortalized primary host cell types (human colonic epithelial [HCE] cells and human carotid artery endothelial [HCAE] cells) followed by transcriptome sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) to investigate transcriptional and epigenetic host cell responses. We observed that F. nucleatum-induced host cell transcriptional modulation involves strong upregulation of genes related to immune migration and inflammatory processes, such as TNF, CXCL8, CXCL1, and CCL20. Furthermore, we identified genes strongly upregulated in a cell line-specific manner. In HCE cells, overexpressed genes included UBD and DUOX2/DUOXA2, associated with p53 degradation-mediated proliferation and intestinal reactive oxygen species (ROS) production, respectively. In HCAE cells, overexpressed genes included EFNA1 and LIF, two genes commonly upregulated in colorectal cancer and associated with poor patient outcomes, and PTGS2 (COX2), a gene associated with the protective effect of aspirin in the colorectal cancer setting. Interestingly, we also observed downregulation of numerous histone modification genes upon F. nucleatum exposure. We used the ChIP-seq data to annotate chromatin states genome wide and found significant chromatin remodeling following F. nucleatum exposure in HCAE cells, with increased frequencies of active enhancer and low-signal/quiescent states. Thus, our results highlight increased inflammation and chemokine gene expression as conserved host cell responses to F. nucleatum exposure and extensive host cell epigenomic changes specific to host cell type. IMPORTANCE Fusobacterium nucleatum is a bacterium normally found in the healthy oral cavity but also has an emerging role in colorectal cancer and other cancer settings. The host-microbe interactions of F. nucleatum and its involvement in tumor initiation, progression, and treatment resistance are not fully understood. We explored host cell changes that occur in response to F. nucleatum. We identified key genes differentially expressed in response to various conditions of F. nucleatum exposure and determined that the conserved host cell response to F. nucleatum was dominated by increased inflammation and chemokine gene expression. Additionally, we found extensive host cell epigenomic changes as a novel aspect of host modulation associated with F. nucleatum exposure. These results extend our understanding of F. nucleatum as an emerging pathogen and highlight the importance of considering strain heterogeneity and host cell phenotypic variation when exploring pathogenic mechanisms of F. nucleatum.

Cytotoxic effects of dental calculus particles and freeze-dried Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum on HSC-2 oral epithelial cells and THP-1 macrophages

BACKGROUND

Periodontitis is an inflammatory disease initiated by dental deposits. Microorganisms in the dental biofilm induce cell death in epithelial cells, contributing to the breakdown of epithelial barrier function. Recently, dental calculus has also been implicated in pyroptotic cell death in oral epithelium. We analyzed the cytotoxic effects of dental calculus and freeze-dried periodontopathic bacteria on oral epithelial cells and macrophages.

METHODS

HSC-2 (human oral squamous carcinoma cells) and phorbol 12-myristate 13-acetate-differentiated THP-1 macrophages were exposed to dental calculus or one of two species of freeze-dried bacterium, Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum. Following incubation for 24 hours, we measured cytotoxicity via lactate dehydrogenase release. Cells were then incubated with glyburide, an NLRP3 inflammasome inhibitor, to assess the potential role of pyroptosis. We also conducted a permeability assay to analyze the effects on epithelial barrier function.

RESULTS

Dental calculus induced dose-dependent cell death in HSC-2 cells, whereas cell death induced by freeze-dried bacteria was insignificant. Conversely, freeze-dried bacteria induced more cell death than dental calculus in THP-1 macrophages. Cell death induced by dental calculus but not by freeze-dried bacteria was inhibited by glyburide, indicating that these are different types of cell death. In the permeability assays, dental calculus but not freeze-dried bacteria attenuated the barrier function of HSC-2 cell monolayers.

CONCLUSION

Due to the low sensitivity of HSC-2 cells to microbial cytotoxicity, dental calculus had stronger cytotoxic effects on HSC-2 cell monolayers than freeze-dried A. actinomycetemcomitans and F. nucleatum, suggesting that it plays a critical role in the breakdown of crevicular/pocket epithelium integrity.

Paradigm shift in the pathogenesis and treatment of oral cancer and other cancers focused on the oralome and antimicrobial-based therapeutics

The oral microbiome is a community of microorganisms, comprised of bacteria, fungi, viruses, archaea, and protozoa, that form a complex ecosystem within the oral cavity. Although minor perturbations in the environment are frequent and compensable, major shifts in the oral microbiome can promote an unbalanced state, known as dysbiosis. Dysbiosis can promote oral diseases, including periodontitis. In addition, oral dysbiosis has been associated with other systemic diseases, including cancer. The objective of this review is to evaluate the epidemiologic evidence linking periodontitis to oral, gastrointestinal, lung, breast, prostate, and uterine cancers, as well as describe new evidence and insights into the role of oral dysbiosis in the etiology and pathogenesis of the cancer types discussed. Finally, we discuss how antimicrobials, antimicrobial peptides, and probiotics may be promising tools to prevent and treat these cancers, targeting both the microbes and associated carcinogenesis processes. These findings represent a novel paradigm in the pathogenesis and treatment of cancer focused on the oral microbiome and antimicrobial‐based therapies.

Porphyromonas gingivalis outer membrane vesicles inhibit the invasion of Fusobacterium nucleatum into oral epithelial cells by downregulating FadA and FomA

Background

Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum) participate in the formation and progression of periodontitis. They can exert virulence by invading into host cells, but the interaction between them and their specific mechanisms remain unclear. The purpose of this study was to study the effect of P. gingivalis outer membrane vesicles (OMVs) on the ability of F. nucleatum to invade oral epithelial cells, and the reasons for the influence.

Methods

The invasion abilities of the two bacteria were detected separately after mixed infection of P. gingivalis and F. nucleatum. Next, P. gingivalis OMVs were extracted with the kit, and their influence on the invasion ability of F. nucleatum was tested. The effects of P. gingivalis OMVs on F. nucleatum were evaluated by assessment of bacterial morphology, growth curves, auto‐aggregation morphology, and the expression of adhesion‐related proteins FadA and FomA.

Results

Our results showed that P. gingivalis inhibited the invasion of F. nucleatum into oral epithelial cells but F. nucleatum promoted the invasion of P. gingivalis. In subsequent experiments, we extracted P. gingivalis OMVs successfully and revealed that proteases in P. gingivalis OMVs inhibited the invasion of F. nucleatum into oral epithelial cells. Furthermore, P. gingivalis OMVs did not affect the morphology and proliferation of F. nucleatum, but proteases inside decreased the auto‐aggregation of F. nucleatum. Additionally, proteases in P. gingivalis OMVs reduced the expression levels of F. nucleatum surface adhesion‐related proteins FadA and FomA.

Conclusion

Our study demonstrated that proteases in P. gingivalis OMVs inhibited the invasion of F. nucleatum into oral epithelial cells by downregulating FadA and FomA.

TIMEOR: a web-based tool to uncover temporal regulatory mechanisms from multi-omics data

Uncovering how transcription factors regulate their targets at DNA, RNA and protein levels over time is critical to define gene regulatory networks (GRNs) and assign mechanisms in normal and diseased states. RNA-seq is a standard method measuring gene regulation using an established set of analysis stages. However, none of the currently available pipeline methods for interpreting ordered genomic data (in time or space) use time-series models to assign cause and effect relationships within GRNs, are adaptive to diverse experimental designs, or enable user interpretation through a web-based platform. Furthermore, methods integrating ordered RNA-seq data with protein–DNA binding data to distinguish direct from indirect interactions are urgently needed. We present TIMEOR (Trajectory Inference and Mechanism Exploration with Omics data in R), the first web-based and adaptive time-series multi-omics pipeline method which infers the relationship between gene regulatory events across time. TIMEOR addresses the critical need for methods to determine causal regulatory mechanism networks by leveraging time-series RNA-seq, motif analysis, protein–DNA binding data, and protein-protein interaction networks. TIMEOR’s user-catered approach helps non-coders generate new hypotheses and validate known mechanisms. We used TIMEOR to identify a novel link between insulin stimulation and the circadian rhythm cycle. TIMEOR is available at https://github.com/ashleymaeconard/TIMEOR.git and http://timeor.brown.edu.

Parathyroid hormone-related protein inhibits nitrogen-containing bisphosphonate-induced apoptosis of human periodontal ligament fibroblasts by activating MKP1 phosphatase

Massive production of reactive oxygen species (ROS) in human periodontal ligament fibroblasts (HPdLFs) by nitrogen-containing bisphosphonates (BPs) is the main factor causing BP-related osteonecrosis of the jaw. Further, oxidative stress and apoptosis of fibroblasts induced by ROS are closely associated with the activation of MAPK. Parathyroid hormone-related protein (PTHrP) can block the activity of MAPK by regulating the levels of MAPK phosphatase 1 (MKP1). Therefore, it is speculated that PTHrP can inhibit the apoptosis of HPdLFs caused by nitrogen-containing BP via regulating the expression levels of MKP1. Herein, alendronate sodium salt trihydrate (nitrogen-containing BP, FOS) and HPdLFs were co-cultured for 24 h, 48 h, and 72 h, and the levels of ROS and apoptosis were determined, respectively. After 48 h co-culture, FOS significantly increased the levels of ROS and apoptosis, and high phosphorylation levels of p38, ERK1/2 and p66^Shc were found in this study. However, the inhibitors of p38 and ERK1/2 significantly reduced the apoptosis of HPdLFs. Interestingly, PTHrP pre-treatment significantly reduced the phosphorylation levels of p38, ERK1/2, and p66^Shc. More importantly, MKP1 inhibitor sanguinarine inhibited the dephosphorylation levels of p38, ERK1/2, and p66^Shc caused by PTHrP. Altogether, PTHrP can inhibit nitrogen-containing BP-induced apoptosis of HPdLFs by activating MKP1 phosphatase.

Oral microbiota and vitamin D impact on oropharyngeal squamous cell carcinogenesis: a narrative literature review

An emerging body of research is revealing the microbiota pivotal involvement in determining the health or disease state of several human niches, and that of vitamin D also in extra-skeletal regions. Nevertheless, much of the oral microbiota and vitamin D reciprocal impact in oropharyngeal squamous cell carcinogenesis (OPSCC) is still mostly unknown. On this premise, starting from an in-depth scientific bibliographic analysis, this narrative literature review aims to show a detailed view of the state of the art on their contribution in the pathogenesis of this cancer type. Significant differences in the oral microbiota species quantity and quality have been detected in OPSCC-affected patients; in particular, mainly high-risk human papillomaviruses (HR-HPVs), Fusobacterium nucleatum, Porphyromonas gingivalis, Pseudomonas aeruginosa, and Candida spp. seem to be highly represented. Vitamin D prevents and fights infections promoted by the above identified pathogens, thus confirming its homeostatic function on the microbiota balance. However, its antimicrobial and antitumoral actions, well-described for the gut, have not been fully documented for the oropharynx yet. Deeper investigations of the mechanisms that link vitamin D levels, oral microbial diversity and inflammatory processes will lead to a better definition of OPSCC risk factors for the optimization of specific prevention and treatment strategies.

IFN-γ or IL-4 polarization impacts the response of gingival fibroblasts to oral bacteria

BACKGROUND AND OBJECTIVE

We previously reported that gingival fibroblasts (GFs) can be polarized into functionally distinct subtypes, immune-activating but tissue-destructive or tissue-reparative, in response to T helper (Th1) and Th2 stimuli, respectively. The purpose of this study was to evaluate the effect of polarization on GFs responses to oral bacteria.

METHODS

Unprimed (GF(-)) and IFN-γ (GF(IFN-γ)) or IL-4 primed (GF(IL-4)) GFs were stimulated with live Fusobacterium nucleatum or Porphyromonas gingivalis. The mRNA expression of IL-1β, IL-4, LPS-recognizing components (Toll-like receptor (TLR) 4, CD14), molecules involved in antigen presentation (human leukocyte antigen (HLA)-ABC, HLA-DP, CD74, CD40), chemokines (C-X-C motif chemokine (CXCL)10, CXCL11, chemokine (C-C motif) ligand 20 (CCL20)), collagen type 1 alpha 1 (COL1A1), and matrix metalloproteinase (MMP)-1, and the protein levels of IL-1β, CD14, CXCL11, CCL20, and COL1A1 accumulated in supernatants were analyzed using real-time PCR and ELISA.

RESULTS

In response to oral bacteria, the GF(IFN-γ) significantly upregulated the expression of LPS-recognizing components, molecules involved in antigen presentation, CXCL10, and CXCL11, whereas the levels of IL-4 and COL1A1 were downregulated, compared with GF(-). The levels of IL-1β, CCL20, and MMP-1 from GF(IFN-γ) were differently regulated between both bacteria; F. nucleatum was synergistically upregulated, but P. gingivalis was downregulated. The GF(IL-4) stimulated with both bacteria upregulated the levels of IL-4, whereas the levels of TLR4 and chemokines were downregulated, compared with GF(-). The regulation of IL-1β, CD14, CXCL11, CCL20, and COL1A1 proteins showed a similar tendency with mRNA regulation.

CONCLUSION

Polarization of GFs with IFN-γ or IL-4 affected the way that GFs responded to oral bacteria through up or downregulation of inflammatory responses and extracellular matrix control.

A versatile nanocomposite based on nanoceria for antibacterial enhancement and protection from aPDT-aggravated inflammation via modulation of macrophage polarization

Antibacterial photodynamic therapy (aPDT) is of vital importance for the treatment of periodontal diseases due to its great potential on effective elimination of pathogenic bacteria via overwhelming reactive oxygen species (ROS) generation. However, the excessive ROS after the therapeutic process may impose an oxidative stress within periodontal pockets, consequently leading to an irreversible destroy in surrounding tissue and severely limit its biomedical applications. In this study, considering the contradiction between ROS in bacteriostasis and inflammation, the role of ROS in different temporal and spatial states has been fully studied. Accordingly, we have designed composite nanomaterials that can play ROS based aPDT and anti-inflammatory effect by eliminating ROS, taking account of different ratio of photosensitizer/ROS scavenger to realize a time-sequential manner. Herein, a simple multifunctional nanocomposite was fabricated by coating red light-excited photosensitizer chlorin e6 (Ce6) onto nanoceria, achieving simultaneous sterilization and inflammation elimination via a dual directional regulation effect. This nano-based platform could utilize the aPDT for antibacterial purpose in the first stage with red-light irradiation, and subsequently scavenge the residual ROS via nanoceria to modulate host immunity by down-regulating the M1 polarization (pro-inflammatory) of macrophages and up-regulating the M2 polarization (anti-inflammatory and regenerative) of macrophages. Moreover, the local ROS level induced by activated inflammation pathway can be adjusted in a very long time because of the charge conversion effect of CeO₂. The regenerative potential of inflammatory surrounding tissues was improved in the animal model. Our strategy will open a new inspiration to fight against the defects of aPDT in the treatment of periodontal disease, even in the anti-infection therapy for the future clinical application.

Analysis of differentially expressed genes in oral epithelial cells infected with Fusobacterium nucleatum for revealing genes associated with oral cancer

Accumulating evidence links Fusobacterium nucleatum with tumorigenesis. Our previous study demonstrated that F. nucleatum infection can induce epithelial‐mesenchymal transition (EMT) in oral epithelial cells and elaborated a probable signal pathway involved in the induction of EMT. However, the comprehensive profiling and pathways of other candidate genes involved in F. nucleatum promoting malignant transformation remain largely elusive. Here, we analysed the transcriptome profile of HIOECs exposed to F. nucleatum infection. Totally, 3307 mRNAs (ǀLog2FCǀ >1.5) and 522 lncRNAs (ǀLog2FCǀ >1) were identified to be differentially expressed in F. nucleatum‐infected HIOECs compared with non‐infected HIOECs. GO and KEGG pathway analyses were performed to investigate the potential functions of the dysregulated genes. Tumour‐associated genes were integrated, and top 10 hub genes (FYN, RAF1, ATM, FOS, CREB, NCOA3, VEGFA, JAK2, CREM and ATF3) were identified by protein‐protein interaction (PPI) network, and Oncomine was used to validate hub genes' expression. LncRNA‐hub genes co‐expression network comprising 67 dysregulated lncRNAs were generated. Together, our study revealed the alteration of lncRNA and potential hub genes in oral epithelial cells in response to F. nucleatum infection, which may provide new insights into the shift of normal to malignant transformation initiated by oral bacterial infection.

Fusobacterium nucleatum Promotes the Development of Ulcerative Colitis by Inducing the Autophagic Cell Death of Intestinal Epithelial

There is a growing body of evidence which suggests that intestinal microbiota, especially Fusobacterium nucleatum (F. nucleatum), are associated with intestinal immune disease such as ulcerative colitis (UC). The mechanism by which F. nucleatum promotes intestinal epithelial cell (IEC) death remained undefined. Here, we investigated the potential mechanisms about how F. nucleatum aggravates IEC death in UC. We first detected the abundance of F. nucleatum in UC tissues and analyzed its relationship with the clinical characteristics of UC. Next, we explored whether F. nucleatum promotes intestinal epithelial cell death in vitro and in vivo. Furthermore, we extracted lipopolysaccharide (LPS) of the F. nucleatum and examined whether F. nucleatum exacerbates UC via LPS. Our results indicated that F. nucleatum was abundant in UC tissues and was correlated with clinical characteristics. In addition, we demonstrated that F. nucleatum and its LPS aggravated IEC death by promoted IEC autophagy. Furthermore, autophagy inhibitors, chloroquine (CQ), 3-methyladenine (3-MA) or Atg5 silencing prevented IEC death mediated by F. nucleatum, which suggests F. nucleatum may contribute to UC by activating autophagic cell death. All our results uncover a vital role of F. nucleatum in autophagic cell death and UC, giving rise to a new sight for UC therapy by inhibiting excessive IEC autophagy and autophagic cell death.

The Pathogenic Effects of Fusobacterium nucleatum on the Proliferation, Osteogenic Differentiation, and Transcriptome of Osteoblasts

As one of the most common oral diseases, periodontitis is closely correlated with tooth loss in middle-aged and elderly people. Fusobacterium nucleatum (F. nucleatum) contributes to periodontitis, but the evidence in alveolar bone loss is still unclear. In this study, cytological experiments and transcriptome analyses were performed to characterize the biological process abnormalities and the molecular changes of F. nucleatum-stimulated osteoblasts. F. nucleatum could inhibit cell proliferation, promote cell apoptosis, and elevate pro-inflammatory cytokine production of osteoblasts, and it also inhibited osteoblast differentiation and mineralized nodule formation and decreased the expression of osteogenetic genes and proteins. Whole-transcriptome analyses identified a total of 235 transcripts that were differentially expressed in all six time points, most of which were inflammation-related genes. The genes, Ccl2, Ccl20, Csf1, Cx3cl1, Cxcl1, Cxcl3, Il6, Birc3, Map3k8, Nos2, Nfkb2, Tnfrsf1b, and Vcam1, played core roles in a PPI network, and interacted closely with other ones in the infection. In addition, 133 osteogenesis-related differential expression genes (DEGs) were time-serially dynamically changed in a short time-series expression miner (STEM) analysis, which were enriched in multiple cancer-related pathways. The core dynamic DEGs (Mnda, Cyp1b1, Comp, Phex, Mmp3, Tnfrsf1b, Fbln5, and Nfkb2) had been reported to be closely related to the development and metastasis in tumor and cancer progress. This study is the first to evaluate the long-term interaction of F. nucleatum on osteoblasts, which might increase the risk of cell carcinogenesis of normal osteoblasts, and provides new insight into the pathogenesis of bacterial-induced bone destruction.

Minimizing the aerosol-generating procedures in orthodontics in the era of a pandemic: Current evidence on the reduction of hazardous effects for the treatment team and patients

The purpose of this critical review is to list the sources of aerosol production during orthodontic standard procedure, analyze the constituent components of aerosol and their dependency on modes of grinding, the presence of water and type of bur, and suggest a method to minimize the quantity and detrimental characteristics of the particles comprising the solid matter of aerosol. Minimization of water-spray syringe utilization for rinsing is suggested on bonding related procedures, while temporal conditions as represented by seasonal epidemics should be considered for the decision of intervention scheme provided as a preprocedural mouth rinse, in an attempt to reduce the load of aerosolized pathogens. In normal conditions, chlorhexidine 0.2%, preferably under elevated temperature state should be prioritized for reducing bacterial counts. In the presence of oxidation vulnerable viruses within the community, substitute strategies might be represented by the use of povidone iodine 0.2%-1%, or hydrogen peroxide 1%. After debonding, extensive material grinding, as well as aligner related attachment clean-up, should involve the use of carbide tungsten burs under water cooling conditions for cutting efficiency enhancement, duration restriction of the procedure, as well as reduction of aerosolized nanoparticles. In this respect, selection strategies of malocclusions eligible for aligner treatment should be reconsidered and future perspectives may entail careful and more restricted utilization of attachment grips. For more limited clean-up procedures, such as grinding of minimal amounts of adhesive remnants, or individualized bracket debonding in the course of treatment, hand-instruments for remnant removal might well represent an effective strategy. Efforts to minimize the use of rotary instrumentation in orthodontic settings might also lead the way for future solutions. Measures of self-protection for the treatment team should never be neglected. Dressing gowns and facemasks with filter protection layers, appropriate ventilation and fresh air flow within the operating room comprise significant links to the overall picture of practice management. Risk management considerations should be constant, but also updated as new material applications come into play, while being grounded on the best available evidence.

Are Denture Adhesives Safe for Oral Cells?

PURPOSE

To compare the cytotoxicity of six commercially available denture adhesives on human gingival cells: Poligrip Flavour Free Fixative Cream, Fixodent Pro Duo Protection, Novafix cream, FittyDent, Polident Total Action, and Fixodent Pro Plus Duo Protection.

MATERIAL AND METHODS

Eluates of denture adhesives were brought into contact with human gingival cells and compared to untreated cells (w/o any dental adhesive elute). Cell toxicity was assessed by measuring cell viability (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assays), cell morphology (immunofluorescence assays), induction of apoptosis/necrosis and production of reactive oxygen species (ROS) (flow cytometry assays). In addition, the pH of each sample was determined. Data were analyzed using one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparisons test.

RESULTS

All denture adhesives tested led to a reduction in pH, especially Fixodent Pro Duo Protection and Fixodent Pro Plus Duo Protection. The cell viability assays showed that Fixodent Pro Duo Protection (1:1 72 hours, p = 3.04 × 10^-6 ; 1:2 72 hours, p = 2.07 × 10^-6 ; 1:4 72 hours, p = 2.04 × 10^-6 ) and Fixodent Pro Plus Duo Protection (1:1 72 hours, p = 2.01 × 10^-6 ; 1:2 72 hours, p = 3.03 × 10^-6 ; 1:4 72 hours, p = 2.02 × 10^-6 ) significantly decreased cell viability at all dilutions. Compared to the control group and the rest of the adhesives, Poligrip Flavour Free Fixative Cream (PFF 1:1 72 hours, p = 2.24 × 10^-6 ; 1:2 72 hours, p = 2.44 × 10^-6 ; 1:4 72 hours, p = 2.04 × 10^-6 ) showed a significantly higher cell viability score at all dilutions. Fixodent Pro Duo Protection and Fixodent Pro Plus Duo Protection, both adhesives containing zinc salts in their composition, were responsible for necrosis, and the number of cells was much reduced, with aberrant morphology and pyknotic nucleus. Finally, Fixodent (1:2, p = 2.04 × 10^-6 , 1:4, p = 0.00036; 1:2, p = 8.82 × 10^-6 , 1:4, p = 2.30 × 10^-6 ) products significantly promoted ROS production in gingival cells.

CONCLUSIONS

The results suggest that denture adhesives containing zinc in their composition could be responsible of the decrease of cell viability, ROS production, aberrant cell morphology, and induction of apoptosis and cell death. However, other possible additional cytotoxic factors must be considered. Thus, more studies are necessary to confirm this hypothesis.