Endothelial Cell Response to Fusobacterium nucleatum

Gut Microbiome and colorectal cancer: discovery of bacterial changes with metagenomics application in Turkısh population

BACKGROUND

Colorectal cancer (CRC) is the 3rd most common cancer in the world and colonic carcinogenesis is a multifactorial disease that involves environmental and genetic factors. Gut microbiota plays a critical role in the regulation of intestinal homeostasis. Increasing evidence shows that the gut microbiome plays a role in CRC development and may be a biomarker for early diagnosis.

OBJECTIVE

This study aimed to determine the clinical prognostic significance of gut microbiota in CRC patients in the Turkish population by metagenomic analysis and to determine the microbial composition in tumor tissue biopsy samples.

METHODS

Tissue biopsies were taken from the participants with sterile forceps during colonoscopy and stored at -80 °C. Then, DNA isolation was performed from the tissue samples and the V3-V4 region of the 16 S rRNA gene was sequenced on the Illumina MiSeq platform. Quality control of the obtained sequence data was performed. Operational taxonomic units (OTUs) were classified according to the Greengenes database. Alpha diversity (Shannon index) and beta diversity (Bray-Curtis distance) analyses were performed. The most common bacterial species in CRC patients and healthy controls were determined and whether there were statistically significant differences between the groups was tested.

RESULTS

A total of 40 individuals, 13 CRC patients and 20 healthy control individuals were included in our metagenomic study. The mean age of the patients was 64.83 and BMI was 25.85. In CRC patients, the level of Bacteroidetes at the phylum taxonomy was significantly increased (p = 0.04), the level of Clostridia at the class taxonomy was increased (p = 0.23), and the level of Enterococcus at the genus taxonomy was significantly increased (p = 0.01). When CRC patients were compared with the control group, significant increases were detected in the species of Gemmiger formicilis (p = 0.15), Prevotella copri (p = 0.02) and Ruminococcus bromii (p = 0.001) at the species taxonomy.

CONCLUSIONS

Metagenomic analysis of intestinal microbiota composition in CRC patients provides important data for determining the treatment options for these patients. The results of this study suggest that it may be beneficial in terms of early diagnosis, poor prognosis and survival rates in CRC patients. In addition, this metagenomic study is the first study on the colon microbiome associated with CRC mucosa in the Turkish population.

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.

Identification of consensus head and neck cancer-associated microbiota signatures: a systematic review and meta-analysis of 16S rRNA and The Cancer Microbiome Atlas datasets

Introduction. Multiple reports have attempted to describe the tumour microbiota in head and neck cancer (HNSC).Gap statement. However, these have failed to produce a consistent microbiota signature, which may undermine understanding the importance of bacterial-mediated effects in HNSC.Aim. The aim of this study is to consolidate these datasets and identify a consensus microbiota signature in HNSC.Methodology. We analysed 12 published HNSC 16S rRNA microbial datasets collected from cancer, cancer-adjacent and non-cancer tissues to generate a consensus microbiota signature. These signatures were then validated using The Cancer Microbiome Atlas (TCMA) database and correlated with the tumour microenvironment phenotypes and patient's clinical outcome.Results. We identified a consensus microbial signature at the genus level to differentiate between HNSC sample types, with cancer and cancer-adjacent tissues sharing more similarity than non-cancer tissues. Univariate analysis on 16S rRNA datasets identified significant differences in the abundance of 34 bacterial genera among the tissue types. Paired cancer and cancer-adjacent tissue analyses in 16S rRNA and TCMA datasets identified increased abundance in Fusobacterium in cancer tissues and decreased abundance of Atopobium, Rothia and Actinomyces in cancer-adjacent tissues. Furthermore, these bacteria were associated with different tumour microenvironment phenotypes. Notably, high Fusobacterium signature was associated with high neutrophil (r=0.37, P<0.0001), angiogenesis (r=0.38, P<0.0001) and granulocyte signatures (r=0.38, P<0.0001) and better overall patient survival [continuous: HR 0.8482, 95 % confidence interval (CI) 0.7758-0.9273, P=0.0003].Conclusion. Our meta-analysis demonstrates a consensus microbiota signature for HNSC, highlighting its potential importance in this disease.

Hypoxia dissociates HDAC6/FOXO1 complex and aggregates them into nucleus to regulate autophagy and osteogenic differentiation

OBJECTIVE

This research aimed to elucidate the molecular mechanisms underlying the periodontitis-associated bone loss, with particular emphasis on the contributory role of hypoxic microenvironment in this process.

BACKGROUND

Periodontitis generally causes alveolar bone loss and is often associated with a hypoxic microenvironment, which affects bone homeostasis. However, the regulating mechanism between hypoxia and jaw metabolism remains unclear. Hypoxia triggers autophagy, which is closely related to osteogenic differentiation, but how hypoxia-induced autophagy regulates bone metabolism is unknown. HDAC6 and FOXO1 are closely related to bone metabolism and autophagy, respectively, but whether they are related to hypoxia-induced bone loss and their internal mechanisms is still unclear.

METHODS

Established rat nasal obstruction model and hypoxia cell model. Immunohistochemistry was performed to detect the expression and localization of HDAC6 and FOXO1 proteins, analysis of autophagic flux and transmission electron microscopy was used to examine the autophagy level and observe the autophagosomes, co-immunoprecipitation and chromatin immunoprecipitation were preformed to investigate the interaction of HDAC6 and FOXO1.

RESULTS

Hypoxia causes increased autophagy and reduced osteogenic differentiation in rat mandibles and BMSCs, and blocking autophagy can attenuate hypoxia-induced osteogenic differentiation decrease. Moreover, hypoxia dissociated the FOXO1-HDAC6 complex and accumulated them in the nucleus. Knocking down of FOXO1 or HDAC6 alleviated hypoxia-induced autophagy elevation or osteogenic differentiation reduction by binding to related genes, respectively.

CONCLUSION

Hypoxia causes mandibular bone loss and autophagy elevation. Mechanically, hypoxia dissociates the FOXO1-HDAC6 complex and aggregates them in the nucleus, whereas HDAC6 decreases osteogenic differentiation and FOXO1 enhances autophagy to inhibit osteogenic differentiation.

The Roles of Periodontal Bacteria in Atherosclerosis

Atherosclerosis (AS) is an inflammatory vascular disease that constitutes a major underlying cause of cardiovascular diseases (CVD) and stroke. Infection is a contributing risk factor for AS. Epidemiological evidence has implicated individuals afflicted by periodontitis displaying an increased susceptibility to AS and CVD. This review concisely outlines several prevalent periodontal pathogens identified within atherosclerotic plaques, including Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum. We review the existing epidemiological evidence elucidating the association between these pathogens and AS-related diseases, and the diverse mechanisms for which these pathogens may engage in AS, such as endothelial barrier disruption, immune system activation, facilitation of monocyte adhesion and aggregation, and promotion of foam cell formation, all of which contribute to the progression and destabilization of atherosclerotic plaques. Notably, the intricate interplay among bacteria underscores the complex impact of periodontitis on AS. In conclusion, advancing our understanding of the relationship between periodontal pathogens and AS will undoubtedly offer invaluable insights and potential therapeutic avenues for the prevention and management of AS.

Fusobacterium nucleatum promotes proliferation in oesophageal squamous cell carcinoma via AHR/CYP1A1 signalling

Fusobacterium nucleatum (Fn) is reportedly involved in poor prognosis of oesophageal squamous cell carcinoma (ESCC), but the responsible mechanisms remain unclear. The present study aimed to explore the function of Fn in ESCC progression, and to identify the key genes or signals involved. Fluorescence in situ hybridization and quantitative PCR assays were applied to measure the abundance of Fn in ESCC tissues, finding that ESCC tissues displayed a higher abundance of Fn compared to adjacent tissues. Furthermore, Fn abundance in advanced ESCC tissues was found to be higher than that in early stage ESCC. The proliferation assays and wound healing assays indicated that Fn infection promoted ESCC cell proliferation and migration. Based on high-throughput sequencing, cytochrome P450 1A1 (CYP1A1) was the most significantly upregulated (eightfold increase) gene, and AKT signalling was activated in KYSE-450 cells treated with Fn. Knocking down CYP1A1 or inactivating AKT signalling with LY294002 downregulated p-AKT^S473 , inhibited cell proliferation, and compromised the proliferation effect induced by Fn in both in vitro and in vivo experiments. Inactivating the aryl hydrocarbon receptor (AHR) by CH-223191 reversed CYP1A1 expression induced by Fn and inhibited the proliferation of ESCC cells. Taken together, our findings indicate that Fn may promote ESCC cell proliferation via AHR/CYP1A1/AKT signalling. Targeting Fn or AHR/CYP1A1 signalling could yield approaches relevant to the treatment of ESCC.

Fusobacterium nucleatum and its associated systemic diseases: epidemiologic studies and possible mechanisms

Background

Fusobacterium nucleatum (F. nucleatum) is an anaerobic oral commensal and the major coaggregation bridge organism linking early and late colonisers. In recent years, a large number of studies suggest that F. nucleatum is closely related to the development of various systemic diseases, such as cardiovascular diseases, adverse pregnancy outcomes, inflammatory bowel diseases, cancer, Alzheimer's disease, respiratory infection, rheumatoid arthritis, etc.

Objective

To review the effect of F. nucleatum on systemic diseases and its possible pathogenesis and to open new avenues for prevention and treatment of F. nucleatum-associated systemic diseases.

Design

The research included every article published up to July 2022 featuring the keywords 'Systemic diseases' OR 'Atherosclerotic cardiovascular diseases' OR 'Atherosclerosis' OR 'Adverse pregnancy outcomes' OR 'Inflammatory bowel disease' OR 'Ulcerative colitis' OR 'Crohn’s disease' OR 'Cancers' OR 'Oral squamous cell carcinomas' OR 'Gastrointestinal cancers' OR 'Colorectal cancer' OR 'Breast cancer' OR 'Genitourinary cancers' OR 'Alzheimer’s disease ' OR 'Rheumatoid arthritis' OR 'Respiratory diseases' AND 'Fusobacterium nucleatum' OR 'Periodontal pathogen' OR 'Oral microbiota' OR 'Porphyromonas gingivalis' and was conducted in the major medical databases.

Results

F. nucleatum can induce immune response and inflammation in the body through direct or indirect pathways, and thus affect the occurrence and development of systemic diseases. Only by continuing to investigate the pathogenic lifestyles of F. nucleatum will we discover the divergent pathways that may be leveraged for diagnostic, preventive and therapeutic purposes.

Optical spectral diagnostics of the oxygenation level in periodontal tissues and photodynamic therapy using methylene blue in children with cerebral palsy

Dental diseases occur in children with cerebral palsy three times higher than in healthy children. Low values of the unstimulated salivation rate (<0.3 ml per minute), pH and buffer capacity, changes in enzyme activity and sialic acid concentration, as well as increased saliva osmolarity and total protein concentration, which indicates impaired hydration, are the factors in the development of a gingiva disease in case of cerebral palsy. This leads to increased bacterial agglutination and the formation of acquired pellicle and biofilm, leading to the formation of dental plaque. There is a tendency toward an increase in the concentration of hemoglobin and a decrease in the degree of hemoglobin oxygenation, as well as an increase in the generation of reactive oxygen and nitrogen species. Photodynamic therapy (PDT) with the use of photosensitizer methylene blue improves blood circulation and the degree of oxygenation in periodontal tissues, as well as eliminates a bacterial biofilm. Analysis of back diffuse reflection spectra makes it possible to conduct non-invasive monitoring determine tissue areas with a low level of hemoglobin oxygenation for precision photodynamic exposure.

Aim

To improve the effectiveness of phototheranostics methods using, namely PDT with simultaneous optical-spectral control, for the treatment of gingivitis in children with complex dental and somatic status (cerebral palsy).

Methods

The study involved 15 children (6-18 y.o.) with various forms of cerebral palsy, in particular, spastic diplegia and atonic-astatic form and with gingivitis. The degree of hemoglobin oxygenation was measured in tissues before PDT and on the 12th day. PDT was performed using laser radiation (λ = 660 nm) with a power density of 150 mW/cm² with a five-minute application of 0.01% MB. The total light dose was 45 ± 15 J/cm². For statistical evaluation of the results, a paired Student's t-test was used.

Results

The paper presents the results of phototheranostics using methylene blue in children with cerebral palsy. An increase in the level of hemoglobin oxygenation from 50 to 67% (p < 0.001) and a decrease in blood volume in the microcirculatory bed of periodontal tissues were shown.

Conclusion

Photodynamic therapy methods with application of methylene blue make it possible to assess the state of the gingival mucosa tissue diseases objectively in real time, and to provide effective targeted therapy for gingivitis in children with cerebral palsy. There is a prospect that they can become widely used clinical methods.

Fusobacterium nucleatum and colorectal cancer: From phenomenon to mechanism

Colorectal cancer(CRC) is the third most frequent malignant tumor. The gut microbiome acts as a vital component of CRC etiology. Fusobacterium nucleatum(Fn) is a key member of colorectal cancer-associated bacteria. But we lack a systematic and in-depth understanding on its role in CRC evolution. In this article, We reviewed the abundance changes and distribution of Fn in CRC occurrence and development, potential effect of Fn in the initiation of CRC, the source of intratumoral Fn and the cause of its tropism to CRC. In addition, We described the mechanism by which Fn promotes the malignant biological behavior of CRC, affects CRC response to therapy, and shapes the tumor immune microenvironment in great detail. Based on the relationship between Fn and CRC, we proposed strategies for CRC prevention and treatment, and discussed the feasibility and limitations of specific cases, to gain insights into further basic and clinical research in the future.

Transcriptome Analysis Reveals Modulation of Human Stem Cells from the Apical Papilla by Species Associated with Dental Root Canal Infection

Interaction of oral bacteria with stem cells from the apical papilla (SCAP) can negatively affect the success of regenerative endodontic treatment (RET). Through RNA-seq transcriptomic analysis, we studied the effect of the oral bacteria Fusobacterium nucleatum and Enterococcus faecalis, as well as their supernatants enriched by bacterial metabolites, on the osteo- and dentinogenic potential of SCAPs in vitro. We performed bulk RNA-seq, on the basis of which differential expression analysis (DEG) and gene ontology enrichment analysis (GO) were performed. DEG analysis showed that E. faecalis supernatant had the greatest effect on SCAPs, whereas F. nucleatum supernatant had the least effect (Tanimoto coefficient = 0.05). GO term enrichment analysis indicated that F. nucleatum upregulates the immune and inflammatory response of SCAPs, and E. faecalis suppresses cell proliferation and cell division processes. SCAP transcriptome profiles showed that under the influence of E. faecalis the upregulation of VEGFA, Runx2, and TBX3 genes occurred, which may negatively affect the SCAP's osteo- and odontogenic differentiation. F. nucleatum downregulates the expression of WDR5 and TBX2 and upregulates the expression of TBX3 and NFIL3 in SCAPs, the upregulation of which may be detrimental for SCAPs' differentiation potential. In conclusion, the present study shows that in vitro, F. nucleatum, E. faecalis, and their metabolites are capable of up- or downregulating the expression of genes that are necessary for dentinogenic and osteogenic processes to varying degrees, which eventually may result in unsuccessful RET outcomes. Transposition to the clinical context merits some reservations, which should be approached with caution.

Salivary Microbiota Associated with Peripheral Microvascular Endothelial Dysfunction

AIMS

Oral health is associated with atherosclerotic cardiovascular disease (ACVD). We previously identified the salivary microbiota characteristics of patients with ACVD. However, whether salivary microbiota is characteristic under impaired vascular endothelial function before ACVD onset remains unclear. Therefore, we aimed to evaluate the characteristics of salivary microbiota associated with peripheral microvascular endothelial dysfunction.

METHODS

We collected saliva samples from 172 community-dwelling elderly individuals without a history of ACVD and performed 16S rRNA metagenomic analysis. We assessed the peripheral microvascular endothelial function using reactive hyperemia index (RHI) and compared the salivary microbiota in the groups with normal (RHI ≥ 2.10), borderline, and abnormal (RHI ＜1.67) peripheral endothelial function. Furthermore, we applied machine learning techniques to evaluate whether salivary microbiota could discriminate between individuals with normal and abnormal endothelial function.

RESULTS

The number of operational taxonomic units (OTUs) was higher in the abnormal group than in the normal group (p=0.037), and differences were found in the overall salivary microbiota structure (unweighted UniFrac distances, p=0.038). The linear discriminant analysis (LDA) effect size (LEfSe) algorithm revealed several significantly differentially abundant bacterial genera between the two groups. An Extra Trees classifier model was built to discriminate between groups with normal and abnormal vascular endothelial function based on the microbial composition at the genus level (AUC=0.810).

CONCLUSIONS

The salivary microbiota in individuals with endothelial dysfunction was distinct from that in individuals with normal endothelial function, indicating that the salivary microbiota may be related to endothelial function.

Fusobacterium nucleatum mediates endothelial damage and increased permeability following single species and polymicrobial infection

BACKGROUND

Numerous lines of evidence link periodontal pathobionts and their virulence factors with endothelial damage. Most research has been conducted using single species infections at the exclusion of other periodontal microorganisms that have been identified in vascular tissue. Here, we assessed endothelial infection with either single or mixed periodontal species infection and examined their effect on endothelial damage and permeability.

METHODS

Cell surface abundance of platelet endothelial cell adhesion molecule-1 (PECAM-1) or endothelial permeability following infection with Porphyromonas gingivalis, Fusobacterium nucleatum subspecies (ssp) nucleatum, ssp polymorphum or Tannerella forsythia as single or mixed species infection was determined by flow cytometry and a fluorescent dextran permeability assay. Zebrafish embryos were infected systemically with either single or mixed species with mortality and disease measured over time.

RESULTS

F. nucleatum ssp nucleatum, ssp polymorphum and P. gingivalis significantly reduced PECAM-1 abundance in single species infection, whereas T. forsythia had no effect. F. nucleatum ssp polymorphum caused considerable mortality and morbidity in a zebrafish systemic infection model. Polymicrobial infection underscored the virulence of F. nucleatum ssp polymorphum in particular with increased endothelial cell death and reduced PECAM-1 abundance in co-infection studies with this organism. When injected systemically into zebrafish in polymicrobial infection, fluorescently labeled bacteria were distributed throughout the vasculature and cardiac region where, in some instances, they co-localized with each other.

CONCLUSIONS

These data provide further evidence on the effects of F. nucleatum on endothelium adhesion molecule abundance and permeability while also highlighting the importance of performing polymicrobial infection to study the molecular mechanisms associated with periodontal pathogen-induced vascular damage.

Fusobacterium nucleatum: a new player in regulation of cancer development and therapeutic response

A dysbiosis in microbial diversity or functionality can promote disease development. Emerging preclinical and clinical evidence emphasizes the interplay between microbiota and both disease evolution and the treatment response of different cancers. One bacterium that has garnered much attention in a few cancer microbiota studies is Fusobacterium nucleaum (Fn). To provide updated knowledge of the functional role of Fn in cancer prevention and management, this review summarizes the relationship among Fn, cancer, and chemoimmunotherapy response, with the potential mechanisms of action also intensively discussed, which will benefit the development of strategies to prevent or treat cancer via Fn-based therapeutic interventions.

Gut microbiota modulation: a tool for the management of colorectal cancer

Colorectal cancer (CRC) is the second cause of cancer death and the third most frequently diagnosed cancer. Besides the lifestyle, genetic and epigenetic alterations, and environmental factors, gut microbiota also plays a vital role in CRC development. The interruption of the commensal relationship between gut microbiota and the host could lead to an imbalance in the bacteria population, in which the pathogenic bacteria become the predominant population in the gut. Different therapeutic strategies have been developed to modify the gut immune system, prevent pathogen colonization, and alter the activity and composition of gut microbiota, such as prebiotics, probiotics, postbiotics, antibiotics, and fecal microbiota transplantation (FMT). Even though the employed strategies exhibit promising results, their translation into the clinic requires evaluating potential implications and risks, as well as assessment of their long-term effects. This study was set to review the gut microbiota imbalances and their relationship with CRC and their effects on CRC therapy, including chemotherapy and immunotherapy. More importantly, we reviewed the strategies that have been used to modulate gut microbiota, their impact on the treatment of CRC, and the challenges of each strategy.

The gut microbial metabolite formate exacerbates colorectal cancer progression

The gut microbiome is a key player in the immunomodulatory and protumorigenic microenvironment during colorectal cancer (CRC), as different gut-derived bacteria can induce tumour growth. However, the crosstalk between the gut microbiome and the host in relation to tumour cell metabolism remains largely unexplored. Here we show that formate, a metabolite produced by the CRC-associated bacterium Fusobacterium nucleatum, promotes CRC development. We describe molecular signatures linking CRC phenotypes with Fusobacterium abundance. Cocultures of F. nucleatum with patient-derived CRC cells display protumorigenic effects, along with a metabolic shift towards increased formate secretion and cancer glutamine metabolism. We further show that microbiome-derived formate drives CRC tumour invasion by triggering AhR signalling, while increasing cancer stemness. Finally, F. nucleatum or formate treatment in mice leads to increased tumour incidence or size, and Th17 cell expansion, which can favour proinflammatory profiles. Moving beyond observational studies, we identify formate as a gut-derived oncometabolite that is relevant for CRC progression.

Vascular Changes and Hypoxia in Periodontal Disease as a Link to Systemic Complications

The hypoxic microenvironment caused by oral pathogens is the most important cause of the disruption of dynamic hemostasis between the oral microbiome and the immune system. Periodontal infection exacerbates the inflammatory response with increased hypoxia and causes vascular changes. The chronicity of inflammation becomes systemic as a link between oral and systemic diseases. The vascular network plays a central role in controlling infection and regulating the immune response. In this review, we focus on the local and systemic vascular network change mechanisms of periodontal inflammation and the pathological processes of inflammatory diseases. Understanding how the vascular network influences the pathology of periodontal diseases and the systemic complication associated with this pathology is essential for the discovery of both local and systemic proactive control mechanisms.

Targeting antibiotic tolerance in anaerobic biofilms associated with oral diseases: Human antimicrobial peptides LL-37 and lactoferricin enhance the antibiotic efficacy of amoxicillin, clindamycin and metronidazole

Antimicrobial peptides are receiving increasing attention as potential therapeutic agents for treating biofilm-related infections of the oral cavity. Many bacteria residing in biofilms exhibit an enhanced antibiotic tolerance, which grants intrinsically susceptible microorganisms to survive lethal concentrations of antibiotics. In this study, we examined the effects of two endogenous human antimicrobial peptides, LL-37 and human Lactoferricin, on the antibiotic drug efficacy of amoxicillin, clindamycin and metronidazole in two types of polymicrobial biofilms, which aimed to represent frequent oral diseases: (1) facultative anaerobic (Streptococcus mutans, Streptococcus sanguinis, Actinomyces naeslundii) and (2) obligate anaerobic biofilms (Veillonella parvula, Parvimonas micra, Fusobacterium nucleatum). LL-37 and Lactoferricin enhanced the anti-biofilm effect of amoxicillin and clindamycin in facultative anaerobic biofilms. Metronidazole alone was ineffective against facultative anaerobic biofilms, but the presence of LL-37 and Lactoferricin led to a greater biofilm reduction. Obligate anaerobic biofilms showed an increased drug tolerance to amoxicillin and clindamycin, presumably due to metabolic downshifts of the bacteria residing within the biofilm. However, when combined with LL-37 or Lactoferricin, the reduction of obligate anaerobic biofilms was markedly enhanced for all antibiotics, even for amoxicillin and clindamycin. Furthermore, our results suggest that antimicrobial peptides enhance the dispersion of matured biofilms, which may be one of their mechanisms for targeting biofilms. In summary, our study proves that antimicrobial peptides can serve as an auxiliary treatment strategy for combatting enhanced antibiotic tolerance in bacterial biofilms.

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.

Microbial Community Profiling Distinguishes Left-Sided and Right-Sided Colon Cancer

The difference between left- and right-sided colon cancer has become the focus of global attention, and researchers have found differences in the morbidity, molecular biological characteristics, and response to targeted drug therapy between left- and right-sided colon cancer. Therefore, the identification of more effective predictive indicators is critical for providing guidance to future clinical work. We collected samples from different colon sites and regions and analyzed the identities and distributions of differentially expressed species in the microbiota in the left and right sides of the colon to better explore the pathogenesis of colon cancer and provided a basis for individualized drug therapy. We collected samples from different regions in the body of 40 patients with colon cancer, including stool and tissues. The Subjects were classified into four groups, and this classification was mainly based on the colon cancer distribution. The microbiota composition of the left-sided and right-sided colon samples was assessed by specifically amplifying the V3-V4 region of the 16S rDNA gene from DNA extracts from the samples. These amplicons were examined by Illumina HiSeq 2500 sequencing. The microbial taxa in the left-sided colon samples are more abundant than those in the right-sided colon samples. The flora in the left-sided colon samples, such as Clostridium perfringens and Fusobacterium nucleatum, might be associated with VEGF expression and are more likely to promote colon cancer. The microbiota distribution in the right-sided colon samples is less invasive and harmful and particularly rich in Bifidobacterium dentium. In addition, Streptococcus, which is the target of EGFR, was found to be expressed in both the left- and right-sided colon samples but was found at a higher level in the left-sided colon samples. Additionally, the differential pathways involved in the left-sided colon samples mainly mediate DNA damage, methylation, and histone modifications, whereas those in the right-sided colon samples are dominated by DNA synthesis. The comparison of only the geographical differences revealed a significant difference in the distribution of the microbial population. The adherent microbiota composition and structural changes between the left- and right-sided colon samples might contribute to the development of colon cancer, lead to different morbidities, and further affect the prognosis of patients and their sensitivity to targeted drugs. Therefore, the identification of the differential flora in the colon could be used as an indicator for predicting the occurrence and development of colon cancer, which is also beneficial for future individualized drug therapy.

Salivary and serum markers of angiogenesis in periodontitis in relation to smoking

OBJECTIVE

Angiogenesis is essential in maintenance of periodontal homeostasis, and it is regulated by growth factors and cytokines, including basic fibroblast growth factor (b-FGF), endoglin, platelet and endothelial cell adhesion molecule (PECAM-1), vascular endothelial growth factor (VEGF), soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1). In this study, the salivary and serum concentrations of these angiogenesis-related proteins in relation to smoking and periodontitis were examined.

MATERIAL AND METHODS

Full-mouth periodontal status together with unstimulated whole saliva and serum samples was collected from 78 individuals, including 40 periodontitis patients (20 smokers and 20 nonsmokers) and 38 periodontally healthy controls (20 smokers and 18 nonsmokers). The Luminex®-xMAP™ technique was used for protein analyses.

RESULTS

Concentrations of all tested proteins in saliva as well as VEGF in serum were significantly higher in periodontitis patients than in healthy controls. In smokers, serum concentrations of endoglin (p = 0.017) and sICAM-1 (p = 0.001) were elevated in comparison to nonsmokers. After adjusting for smoking and gender, periodontitis associated significantly with salivary concentrations of b-FGF, PECAM-1, VEGF, sICAM-1, and sVCAM-1 (p < 0.01).

CONCLUSION

Taken together, salivary concentrations of b-FGF, PECAM-1, and VEGF associate with periodontitis. The suppressive effect of smoking on salivary marker levels is limited to periodontitis patients only.

CLINICAL RELEVANCE

Smoking-related suppression of salivary marker levels is observed only in periodontitis patients.

Endogenous murine microbiota member Faecalibaculum rodentium and its human homologue protect from intestinal tumour growth

The microbiota has been shown to promote intestinal tumourigenesis, but a possible anti-tumourigenic effect has also been postulated. Here, we demonstrate that changes in the microbiota and mucus composition are concomitant with tumourigenesis. We identified two anti-tumourigenic strains of the microbiota-Faecalibaculum rodentium and its human homologue, Holdemanella biformis-that are strongly under-represented during tumourigenesis. Reconstitution of ApcMin/+ or azoxymethane- and dextran sulfate sodium-treated mice with an isolate of F. rodentium (F. PB1) or its metabolic products reduced tumour growth. Both F. PB1 and H. biformis produced short-chain fatty acids that contributed to control protein acetylation and tumour cell proliferation by inhibiting calcineurin and NFATc3 activation in mouse and human settings. We have thus identified endogenous anti-tumourigenic bacterial strains with strong diagnostic, therapeutic and translational potential.

Fusobacterium nucleatum promotes epithelial-mesenchymal transiton through regulation of the lncRNA MIR4435-2HG/miR-296-5p/Akt2/SNAI1 signaling pathway

Fusobacterium nucleatum, an anaerobic oral opportunistic pathogen associated with periodontitis, has been considered to be associated with the development of oral squamous cell carcinoma (OSCC). However, the initial host molecular alterations induced by F. nucleatum infection which may promote predisposition to malignant transformation through epithelial–mesenchymal transition (EMT) have not yet been clarified. In the present study, we monitored the ability of F. nucleatum to induce EMT‐associated features, and our results showed that F. nucleatum infection promoted cell migration in either noncancerous human immortalized oral epithelial cells (HIOECs) or the two OSCC cell lines SCC‐9 and HSC‐4, but did not accelerate cell proliferation or cell cycle progression. Mesenchymal markers, including N‐cadherin, Vimentin, and SNAI1, were upregulated, while E‐cadherin was decreased and was observed to translocate to the cytoplasm. Furthermore, FadA adhesin and heat‐inactivated F. nucleatum were found to cause a similar effect as the viable bacterial cells. The upregulated lncRNA MIR4435‐2HG identified by the high‐throughput sequencing was demonstrated to negatively regulate the expression of miR‐296‐5p, which was downregulated in F. nucleatum‐infected HIOECs and SCC‐9 cells. The binding of MIR4435‐2HG and miR‐296‐5p was validated via a dual‐luciferase reporter assay. Additionally, knockdown of MIR4435‐2HG with siRNA leads to a decrease in SNAI1 expression, while miR‐296‐5p could further negatively and indirectly regulate SNAI1 expression via Akt2. Therefore, our study demonstrated that F. nucleatum infection could trigger EMT via lncRNA MIR4435‐2HG/miR‐296‐5p/Akt2/SNAI1 signaling pathway, and EMT process may be a probable link between F. nucleatum infection and initiation of oral epithelial carcinomas.

Persistent Exposure to Fusobacterium nucleatum Triggers Chemokine/Cytokine Release and Inhibits the Proliferation and Osteogenic Differentiation Capabilities of Human Gingiva-Derived Mesenchymal Stem Cells

Fusobacterium nucleatum is one of the most frequent pathogenic bacteria causing periodontitis. The direct effect of Fusobacterium nucleatum (F. nucleatum) on oral stem cells has rarely been reported. In this study, we aimed to evaluate how gingiva-derived mesenchymal stem cells (GMSCs) respond to a direct challenge with F. nucleatum. GMSCs were isolated by the limiting dilution method and exposed to F. nucleatum at various multiplicities of infection (MOIs; F. nucleatum:cell ratios of 10:1, 50:1, and 100:1) for 24 h to 4 weeks. Our results indicated that F. nucleatum significantly inhibited cell proliferation in a dose-dependent manner and promoted cell migration and the release of chemokines/cytokines, such as CCL2, CXCL1, and IL-6. Additionally, F. nucleatum inhibited GMSC osteogenic differentiation partly by decreasing alkaline phosphatase (ALP) activity, mineralized nodule formation, and osteogenesis-related gene and protein expression. RNA-sequencing analyses indicated that F. nucleatum time-dependently activated cellular signaling pathways during the process of osteogenic differentiation. A total of 64 cell differentiation-related genes were found to be differentially expressed between non-infected and F. nucleatum-infected GMSCs at 3, 7, 14, and 21 d. Intriguingly, we discovered that the 64 cell differentiation-related differentially expressed genes (DEGs) were significantly enriched in cancer-related pathways, such as bone cancer, osteosarcoma and bone marrow cancer, which provides new insight into tumorigenesis during the process of GMSC osteogenic differentiation. In conclusion, this study demonstrates that persistent exposure to F. nucleatum promotes cell migration and chemokine/cytokine release and inhibits the proliferation and osteogenic differentiation of GMSCs. Our study provides a novel and long-time bacteria-cell co-culture in vitro model and makes a foundation for the future mechanistic studies of GMSCs under F. nucleatum infection.

Role of NOD1/NOD2 receptors in Fusobacterium nucleatum mediated NETosis

Polymorphonuclear neutrophils (PMNs) are indispensable in fighting infectious microbes by adopting various antimicrobial strategies including phagocytosis and neutrophil extracellular traps (NETs). Although the role and importance of PMNs in periodontal disease are well established, the specific molecular mechanisms involved in NET formation are yet to be characterized. In the present study, we sought to determine the role of periodontal pathogen on NET formation by utilizing Fusobacterium nucleatum. Our data demonstrates that F. nucleatum activates neutrophils and induces robust NETosis in a time-dependent manner via the upregulation of the Nucleotide oligomerization domain 1 (NOD1) and NOD2 receptors. Furthermore, CRISPR/Cas9 knockout of HL-60 cells and the use of ligands/inhibitors confirmed the involvement of NOD1 and NOD2 receptors in F. nucleatum-mediated NET formation. When treated with NOD1 and NOD2 inhibitors, we observed a significant downregulation of peptidylarginine deiminase 4 (PAD4) activity. In addition, neutrophils showed a significant increase and decrease of myeloperoxidase (MPO) and neutrophil elastase (NE) when treated with NOD1/NOD2 ligands and inhibitors, respectively. Taken together, CRISPR/Cas9 knockout of NOD1/NOD2 HL-60 cells and inhibitors of NOD signaling confirmed the role of NLRs in F. nucleatum-mediated NETosis. Our data demonstrates an important pathway linking NOD1 and NOD2 to NETosis by F. nucleatum, a prominent microbe in periodontal biofilms. This is the first study to elucidate the role of NOD-like receptors in NETosis and their downstream signaling network.

Fusobacterium nucleatum stimulates monocyte adhesion to and transmigration through endothelial cells

OBJECTIVE

Fusobacterium nucleatum (F. nucleatum) is an important pathogen in periodontitis. Previous studies have demonstrated its ability to spread via haematogenesis and modulate host immune responses. However, little is known regarding its effect on endothelial cells (ECs) and leukocytes. The aim of this study was to assess the effect of F. nucleatum on monocyte attachment and transmigration through ECs.

DESIGN

Human umbilical vein endothelial cells (HUVECs) and human leukemic monocyte (THP-1) cells were infected with F. nucleatum and assessed for monocyte adhesion, transendothelial migration, and HUVEC proliferation/apoptosis. Real-time PCR, western blotting and ELISA were performed to assess the expression of proinflammatory cytokines, adhesion molecules and chemokines in both cells.

RESULTS

F. nucleatum challenge significantly induced THP-1 cell adhesion and transmigration and markedly impaired cell proliferation and apoptosis in HUVECs. A parallel increase in vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and E-selectin expression in HUVECs and an upregulation of tumour necrosis factor-α, interleukin (IL)-1β, IL-6, IL-8, and monocyte chemoattractant protein-1 in both HUVECs and THP-1 cells were observed. The expression of nuclear factor-kappa B was also enhanced in HUVECs and THP-1 cells upon F. nucleatum infection.

CONCLUSIONS

F. nucleatum triggers an inflammatory response against infection in cells and promotes the recruitment and transmigration of monocytes through ECs.

Omega-3 fatty acids suppress Fusobacterium nucleatum-induced placental inflammation originating from maternal endothelial cells

Fusobacterium nucleatum is an oral anaerobe prevalent in intrauterine infection associated with a wide spectrum of adverse pregnancy outcomes. We demonstrate here that F. nucleatum triggers placental inflammation through maternal, rather than paternal, TLR4-mediated signaling. Elimination of TLR4 from maternal endothelial cells alleviated placental inflammation and reduced fetal and neonatal death, while elimination of TLR4 in the hematopoietic cells had no effect. The placental inflammatory response followed a spatiotemporal pattern, with NF-κB activation observed first in the maternal endothelial cells and then in the decidual cells surrounding the endothelium, followed by induction of inflammatory cytokines and chemokines. Supplementation of pregnant mice with fish oil as a source of omega-3 fatty acids suppressed placental inflammation, reduced F. nucleatum proliferation in the placenta, and increased fetal and neonatal survival. In vitro analysis illustrates that omega-3 fatty acids inhibit bacterial-induced inflammatory responses from human umbilical cord endothelial cells. Our study therefore reveals a mechanism by which microbial infections affect pregnancy and identifies a prophylactic therapy to protect against intrauterine infections.

Fusobacterium nucleatum promotes chemoresistance to 5-fluorouracil by upregulation of BIRC3 expression in colorectal cancer

Background

Emerging evidence suggests a potential relationship between gut microbiota and the host response to chemotherapeutic drugs including 5-fluorouracil (5-Fu). Fusobacterium nucleatum (Fn) has been linked to the initiation and progression of colorectal cancer (CRC). Unfortunately, little was known about the relationship between Fn infection and chemotherapeutic efficacy. Here, we investigate the potential relationship between Fn infection and chemotherapeutic efficacy of 5-Fu in CRC.

Methods

Differentially expressed genes of CRC cell lines induced by Fn infection were analyzed based on a whole genome microarray analysis Then, we explored the relationship between upregulation of BIRC3 induced by Fn infection and chemoresistance to 5-Fu in vitro and in vivo. Furthermore, we dissected the mechanisms involved in Fn-induced BIRC3 expression. Finally, we investigated the clinical relevance of Fn infection, BIRC3 protein expression and chemoresistance to 5-Fu treatment in CRC patients.

Results

BIRC3 was the most upregulated gene induced by Fn infection via the TLR4/NF-κB pathway in CRC cells; Fn infection reduced the chemosensitivity of CRC cells to 5-Fu through upregulation of BIRC3 in vitro and in vivo. High Fn abundance correlated with chemoresistance in advanced CRC patients who received standard 5-Fu-based adjuvant chemotherapy after radical surgery.

Conclusions

Our evidence suggests that Fn and BIRC3 may serve as promising therapeutic targets for reducing chemoresistance to 5-Fu treatment in advanced CRC.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0985-y) contains supplementary material, which is available to authorized users.

Hypoxia-induced endothelial cell responses - possible roles during periodontal disease

Background and objective Inflammatory periodontal pockets are known to be hypoxic. Hypoxia influences vascular response to periodontal inflammation, including angiogenesis, which is critical for oxygen and nutrient delivery to periodontal tissues and granulation tissue formation. Our previous work suggests that periodontal bacteria may actively contribute to pocket hypoxia. Herein, we test the hypothesis that Fusobacterium nucleatum actively induces low oxygen tension, which modulates angiogenesis and endothelial cell activity. HUVEC cells were incubated in 1.5% oxygen for (Folkman & Shing, 1992)48 hours. Cell proliferation was measured by MTT; surface expression of CD31, CD34 and VEGF receptors (VEGFR1, VEGFR2) were analyzed by FACS. mRNA expression of HIF isoforms, iNOS, eNOS, COX-2, and VEGF was measured by quantitative PCR. Supernatants were analyzed for the release of IL-1α, TNF-α, and VEGF by ELISA or multiplex immunoassays and nitric oxide was measured by colorimetric assay. F. nucleatum actively depleted oxygen. Hypoxia resulted in a significant increase of HIF isoforms. iNOS was increased while nitric oxide was unchanged. VEGF release was increased at 4 hours followed by an increase in VEGFR1 at 12 hours, but not VEGFR2. CD31 expression was reduced and CD34 was increased after 48 hours (p < 0.05). IL-1α and TNF-α release were decreased at 4 hours (p < 0.05), but both increased by 24 hours; TNF-α increased at 24 h. The data highlight the role of hypoxia in endothelial cell inflammatory changes. F. nucleatum, considered a bridging species in the development of periodontopathic biofilms induces hypoxia in the periodontium leading to angiogenic changes in periodontal disease pathogenesis.

Green tea prevents vascular disturbs and attenuates periodontal breakdown in long-term hyperglycaemia in T1D rats

AIM

The effects of green tea on the modulation of vascularization during the progression of spontaneous periodontitis in long-term hyperglycaemia in streptozotocin-induced type 1 diabetic (T1D) rats were evaluated.

MATERIALS AND METHODS

Wistar rats normoglycaemic (NG) and T1D were divided into two control groups, which received water (NG-W and T1D-W) and two experimental groups that received green tea (NG-GT and T1D-GT). Periodontal structures were evaluated by microtomographic and histological analyses. Number of immunostained cells for VEGF (NcVEGF+/mm² ) and CD31 (NcCD31+/mm² ), as well microvessel density (MVD) in the periodontal ligament (PDL) were evaluated.

RESULTS

Long-term hyperglycaemia in T1D-W rats induced vascular alterations in PDL with a reduction of 36% in MVD, a decrease of 33% in NcCD31+/mm² and an increase of 53% in NcVEGF+/mm² . Concomitantly, a severe degree of periodontitis with higher reduction in bone volume and periodontal bone level was observed. In T1D-GT, green tea maintained the MVD, NcCD31+/mm² and NcVEGF+/mm² in the PDL similar to normoglycaemic groups. Clinically, in T1D-GT rats, green tea reduced dental plaque accumulation and the degree of periodontitis when compared to T1D-W.

CONCLUSION

Daily green tea consumption has a therapeutic effect on the diabetic vascular disorder in PDL and the progression of periodontitis in long-term hyperglycaemia in T1D rats.

Invasive Fusobacterium nucleatum activates beta-catenin signaling in colorectal cancer via a TLR4/P-PAK1 cascade

The underlying mechanism of Fusobacterium nucleatum (Fn) in the carcinogenesis of colorectal cancer (CRC) is poorly understood. Here, we examined Fn abundance in CRC tissues, as well as β-catenin, TLR4 and PAK1 protein abundance in Fn positive and Fn negative CRCs. Furthermore, we isolated a strain of Fn (F01) from a CRC tissue and examined whether Fn (F01) infection of colon cancer cells activated β-catenin signaling via the TLR4/P-PAK1/P-β-catenin S675 cascade. Invasive Fn was abundant in 62.2% of CRC tissues. TLR4, PAK1 and nuclear β-catenin proteins were more abundant within Fn-positive over Fn-negative CRCs (P < 0.05). Fn and its lipopolysaccharide induced a significant increase in TLR4/P-PAK1/P-β-catenin S675/C-myc/CyclinD1 protein abundance, as well as in the nuclear translocation of β-catenin. Furthermore, inhibition of TLR4 or PAK1 prior to challenge with Fn significantly decreased protein abundance of P-β-catenin S675, C-myc and Cyclin D1, as well as nuclear β-catenin accumulation. Inhibition of TLR4 significantly decreased P-PAK1 protein abundance, and for the first time, we observed an interaction between TLR4 and P-PAK1 using immunoprecipitation. Our data suggest that invasive Fn activates β-catenin signaling via a TLR4/P-PAK1/P-β-catenin S675 cascade in CRC. Furthermore, TLR4 and PAK1 could be potential pharmaceutical targets for the treatment of Fn-related CRCs.

Microbial signatures of oral dysbiosis, periodontitis and edentulism revealed by Gene Meter methodology

Conceptual models suggest that certain microorganisms (e.g., the "red" complex) are indicative of a specific disease state (e.g., periodontitis); however, recent studies have questioned the validity of these models. Here, the abundances of 500+ microbial species were determined in 16 patients with clinical signs of one of the following oral conditions: periodontitis, established caries, edentulism, and oral health. Our goal was to determine if the abundances of certain microorganisms reflect dysbiosis or a specific clinical condition that could be used as a 'signature' for dental research. Microbial abundances were determined by the analysis of 138,718 calibrated probes using Gene Meter methodology. Each 16S rRNA gene was targeted by an average of 194 unique probes (n=25nt). The calibration involved diluting pooled gene target samples, hybridizing each dilution to a DNA microarray, and fitting the probe intensities to adsorption models. The fit of the model to the experimental data was used to assess individual and aggregate probe behavior; good fits (R²>0.90) were retained for back-calculating microbial abundances from patient samples. The abundance of a gene was determined from the median of all calibrated individual probes or from the calibrated abundance of all aggregated probes. With the exception of genes with low abundances (<2 arbitrary units), the abundances determined by the different calibrations were highly correlated (r~1.0). Seventeen genera were classified as 'signatures of dysbiosis' because they had significantly higher abundances in patients with periodontitis and edentulism when contrasted with health. Similarly, 13 genera were classified as 'signatures of periodontitis', and 14 genera were classified as 'signatures of edentulism'. The signatures could be used, individually or in combination, to assess the clinical status of a patient (e.g., evaluating treatments such as antibiotic therapies). Comparisons of the same patient samples revealed high false negatives (45%) for next-generation-sequencing results and low false positives (7%) for Gene Meter results.