Coaggregated E. faecalis with F. nucleatum regulated environmental stress responses and inflammatory effects.

To investigate the cell-cell interactions of intergeneric bacterial species, the study detected the survival of Enterococcus faecalis (Ef) under monospecies or coaggregation state with Fusobacterium nucleatum subsp. polymorphum (Fnp) in environmental stress. Ef and Fnp infected the human macrophages with different forms (Ef and Fnp monospecies, Ef-Fnp coaggregates, Ef + Fnp cocultures) for exploring the immunoregulatory effects and the relevant molecular mechanisms. Meanwhile, the transcriptomic profiles of coaggregated Ef and Fnp were analyzed. Ef was shown to coaggregate with Fnp strongly in CAB within 90 min by forming multiplexes clumps. Coaggregation with Fnp reinforced Ef resistance against unfavorable conditions including alkaline, hypertonic, nutrient-starvation, and antibiotic challenges. Compared with monospecies and coculture species, the coaggregation of Ef and Fnp significantly facilitates both species to invade dTHP-1 cells and aid Ef to survive within the cells. Compared with coculture species, dual-species interaction of Ef and Fnp significantly decreased the levels of pro-inflammatory cytokines IL-6, TNF-α, and chemokines MCP-1 secreted by dTHP-1 cells and lessened the phosphorylation of p38, JNK, and p65 signaling pathways. The transcriptome sequencing results showed that 111 genes were differentially expressed or Ef-Fnp coaggregated species compared to Ef monospecies; 651 genes were differentially expressed for Fnp when coaggregation with Ef. The analysis of KEGG pathway showed that Ef differentially expressed genes (DEGs) were enriched in quorum sensing and arginine biosynthesis pathway; Fnp DEGs were differentially concentrated in lipopolysaccharide (LPS) biosynthesis, biofilm formation, and lysine degradation pathway compared to monospecies. KEY POINTS: • Coaggregated with Fnp aids Ef's survival in environmental stress, especially in root canals after endodontic treatment. • The coaggregation of Ef and Fnp may weaken the pro-inflammatory response and facilitate Ef to evade killed by macrophages. • The coaggregation between Ef and Fnp altered interspecies transcriptional profiles.

Fusobacterium nucleatum infection modulates the transcriptome and epigenome of HCT116 colorectal cancer cells in an oxygen-dependent manner.

Fusobacterium nucleatum, a gram-negative oral bacterium, has been consistently validated as a strong contributor to the progression of several types of cancer, including colorectal (CRC) and pancreatic cancer. While previous in vitro studies have shown that intracellular F. nucleatum enhances malignant phenotypes such as cell migration, the dependence of this regulation on features of the tumor microenvironment (TME) such as oxygen levels are wholly uncharacterized. Here we examine the influence of hypoxia in facilitating F. nucleatum invasion and its effects on host responses focusing on changes in the global epigenome and transcriptome. Using a multiomic approach, we analyze epigenomic alterations of H3K27ac and global transcriptomic alterations sustained within a hypoxia and normoxia conditioned CRC cell line HCT116 at 24 h following initial infection with F. nucleatum. Our findings reveal that intracellular F. nucleatum activates signaling pathways and biological processes in host cells similar to those induced upon hypoxia conditioning in the absence of infection. Furthermore, we show that a hypoxic TME favors F. nucleatum invasion and persistence and therefore infection under hypoxia may amplify malignant transformation by exacerbating the effects induced by hypoxia alone. These results motivate future studies to investigate host-microbe interactions in tumor tissue relevant conditions that more accurately define parameters for targeted cancer therapies.

Evaluation of Fusobacterium nucleatum Enoyl-ACP Reductase (FabK) as a Narrow-Spectrum Drug Target.

Fusobacterium nucleatum, a pathobiont inhabiting the oral cavity, contributes to opportunistic diseases, such as periodontal diseases and gastrointestinal cancers, which involve microbiota imbalance. Broad-spectrum antimicrobial agents, while effective against F. nucleatum infections, can exacerbate dysbiosis. This necessitates the discovery of more targeted narrow-spectrum antimicrobial agents. We therefore investigated the potential for the fusobacterial enoyl-ACP reductase II (ENR II) isoenzyme FnFabK (C4N14_ 04250) as a narrow-spectrum drug target. ENRs catalyze the rate-limiting step in the bacterial fatty acid synthesis pathway. Bioinformatics revealed that of the four distinct bacterial ENR isoforms, F. nucleatum specifically encodes FnFabK. Genetic studies revealed that fabK was indispensable for F. nucleatum growth, as the gene could not be deleted, and silencing of its mRNA inhibited growth under the test conditions. Remarkably, exogenous fatty acids failed to rescue growth inhibition caused by the silencing of fabK. Screening of synthetic phenylimidazole analogues of a known FabK inhibitor identified an inhibitor (i.e., 681) of FnFabK enzymatic activity and F. nucleatum growth, with an IC50 of 2.1 µM (1.0 µg/mL) and a MIC of 0.4 µg/mL, respectively. Exogenous fatty acids did not attenuate the activity of 681 against F. nucleatum. Furthermore, FnFabK was confirmed as the intracellular target of 681 based on the overexpression of FnFabK shifting MICs and 681-resistant mutants having amino acid substitutions in FnFabK or mutations in other genetic loci affecting fatty acid biosynthesis. 681 had minimal activity against a range of commensal flora, and it was less active against streptococci in physiologic fatty acids. Taken together, FnFabK is an essential enzyme that is amenable to drug targeting for the discovery and development of narrow-spectrum antimicrobial agents.

Transcriptome fine-mapping in Fusobacterium nucleatum reveals FoxJ, a new σE-dependent small RNA with unusual mRNA activation activity.

The oral commensal Fusobacterium nucleatum can spread to extra-oral sites, where it is associated with diverse pathologies, including pre-term birth and cancer. Due to the evolutionary distance of F. nucleatum to other model bacteria, we lack a deeper understanding of the RNA regulatory networks that allow this bacterium to adapt to its various niches. As a first step in that direction, we recently showed that F. nucleatum harbors a global stress response governed by the extracytoplasmic function sigma factor, σE, which displays a striking functional conservation with Proteobacteria and includes a noncoding arm in the form of a regulatory small RNA (sRNA), FoxI. To search for putative additional σE-dependent sRNAs, we comprehensively mapped the 5' and 3' ends of transcripts in the model strain ATCC 23726. This enabled the discovery of FoxJ, a ~156-nucleotide sRNA previously misannotated as the 5' untranslated region (UTR) of ylmH. FoxJ is tightly controlled by σE and activated by the same stress conditions as is FoxI. Both sRNAs act as mRNA repressors of the abundant porin FomA, but FoxJ also regulates genes that are distinct from the target suite of FoxI. Moreover, FoxJ differs from other σE-dependent sRNAs in that it also positively regulates genes at the post-transcriptional level. We provide preliminary evidence for a new mode of sRNA-mediated mRNA activation, which involves the targeting of intra-operonic terminators. Overall, our study provides an important resource through the comprehensive annotation of 5' and 3' UTRs in F. nucleatum and expands our understanding of the σE response in this evolutionarily distant bacterium.IMPORTANCEThe oral microbe Fusobacterium nucleatum can colonize secondary sites, including cancer tissue, and likely deploys complex regulatory systems to adapt to these new environments. These systems are largely unknown, partly due to the phylogenetic distance of F. nucleatum to other model organisms. Previously, we identified a global stress response mediated by σE that displays functional conservation with the envelope stress response in Proteobacteria, comprising a coding and noncoding regulatory arm. Through global identification of transcriptional start and stop sites, we uncovered the small RNA (sRNA) FoxJ as a novel component of the noncoding arm of the σE response in F. nucleatum. Together with its companion sRNA FoxI, FoxJ post-transcriptionally modulates the synthesis of envelope proteins, revealing a conserved function for σE-dependent sRNAs between Fusobacteriota and Proteobacteria. Moreover, FoxJ activates the gene expression for several targets, which is a mode of regulation previously unseen in the noncoding arm of the σE response.

Stratification of Fusobacterium nucleatum by local health status in the oral cavity defines its subspecies disease association.

The ubiquitous inflammophilic oral pathobiont Fusobacterium nucleatum (Fn) is widely recognized for its strong association with inflammatory dysbiotic diseases and cancer. Fn is subdivided into four subspecies, which are historically considered functionally interchangeable in the oral cavity. To test this assumption, we analyzed patient-matched dental plaque and odontogenic abscess clinical specimens and examined whether an inflammatory environment selects for/against particular Fn subspecies. Dental plaque harbored a greater diversity of fusobacteria, with Fn. polymorphum dominating, whereas odontogenic abscesses were exceptionally biased for the largely uncharacterized organism Fn. animalis. Comparative genomic analyses revealed significant genotypic distinctions among Fn subspecies that correlate with their preferred ecological niches and support a taxonomic reassignment of each as a distinct Fusobacterium species. Despite originating as a low-abundance organism in dental plaque, Fn. animalis typically outcompetes other oral fusobacteria within the inflammatory abscess environment, which may explain its prevalence in other oral and extraoral diseases.

A distinct Fusobacterium nucleatum clade dominates the colorectal cancer niche.

Fusobacterium nucleatum (Fn), a bacterium present in the human oral cavity and rarely found in the lower gastrointestinal tract of healthy individuals1, is enriched in human colorectal cancer (CRC) tumours2-5. High intratumoural Fn loads are associated with recurrence, metastases and poorer patient prognosis5-8. Here, to delineate Fn genetic factors facilitating tumour colonization, we generated closed genomes for 135 Fn strains; 80 oral strains from individuals without cancer and 55 unique cancer strains cultured from tumours from 51 patients with CRC. Pangenomic analyses identified 483 CRC-enriched genetic factors. Tumour-isolated strains predominantly belong to Fn subspecies animalis (Fna). However, genomic analyses reveal that Fna, considered a single subspecies, is instead composed of two distinct clades (Fna C1 and Fna C2). Of these, only Fna C2 dominates the CRC tumour niche. Inter-Fna analyses identified 195 Fna C2-associated genetic factors consistent with increased metabolic potential and colonization of the gastrointestinal tract. In support of this, Fna C2-treated mice had an increased number of intestinal adenomas and altered metabolites. Microbiome analysis of human tumour tissue from 116 patients with CRC demonstrated Fna C2 enrichment. Comparison of 62 paired specimens showed that only Fna C2 is tumour enriched compared to normal adjacent tissue. This was further supported by metagenomic analysis of stool samples from 627 patients with CRC and 619 healthy individuals. Collectively, our results identify the Fna clade bifurcation, show that specifically Fna C2 drives the reported Fn enrichment in human CRC and reveal the genetic underpinnings of pathoadaptation of Fna C2 to the CRC niche.

miR-135b Aggravates Fusobacterium nucleatum-Induced Cisplatin Resistance in Colorectal Cancer by Targeting KLF13.

Cisplatin resistance is the main cause of colorectal cancer (CRC) treatment failure, and the cause has been reported to be related to Fusobacterium nucleatum (Fn) infection. In this study, we explored the role of Fn in regulating cisplatin resistance of CRC cells and its underlying mechanism involved. The mRNA and protein expressions were examined by qRT-PCR and western blot. Cell proliferation and cell apoptosis were assessed using CCK8 and flow cytometry assays, respectively. Dual-luciferase reporter gene assay was adopted to analyze the molecular interactions. Herein, our results revealed that Fn abundance and miR-135b expression were markedly elevated in CRC tissues, with a favorable association between the two. Moreover, Fn infection could increase miR-135b expression via a concentration-dependent manner, and it also enhanced cell proliferation but reduced apoptosis and cisplatin sensitivity by upregulating miR-135b. Moreover, KLF13 was proved as a downstream target of miR-135b, of which overexpression greatly diminished the promoting effect of miR-135b or Fn-mediated cisplatin resistance in CRC cells. In addition, it was observed that upstream 2.5 kb fragment of miR-135b promoter could be interacted by ß-catenin/TCF4 complex, which was proved as an effector signaling of Fn. LF3, a blocker of ß-catenin/TCF4 complex, was confirmed to diminish the promoting role of Fn on miR-135b expression. Thus, it could be concluded that Fn activated miR-135b expression through TCF4/ß-catenin complex, thereby inhibiting KLF13 expression and promoting cisplatin resistance in CRC.

Exosomes secreted by Fusobacterium nucleatum-infected colon cancer cells transmit resistance to oxaliplatin and 5-FU by delivering hsa_circ_0004085.

BACKGROUND: A large number of Fusobacterium nucleatum (Fn) are present in colorectal cancer (CRC) tissues of patients who relapse after chemotherapy, and Fn has been reported to promote oxaliplatin and 5-FU chemoresistance in CRC. Pathogens such as bacteria and parasites stimulate exosome production in tumor cells, and the regulatory mechanism of exosomal circRNA in the transmission of oxaliplatin and 5-FU chemotherapy resistance in Fn-infected CRC remains unclear. METHODS: Hsa_circ_0004085 was screened by second-generation sequencing of CRC tissues. The correlation between hsa_circ_0004085 and patient clinical response to oxaliplatin/5-FU was analyzed. Exosome tracing experiments and live imaging systems were used to test the effect of Fn infection in CRC on the distribution of hsa_circ_0004085. Colony formation, ER tracking analysis and immunofluorescence were carried out to verify the regulatory effect of exosomes produced by Fn-infected CRC cells on chemotherapeutic resistance and ER stress. RNA pulldown, LC-MS/MS analysis and RIP were used to explore the regulatory mechanism of downstream target genes by hsa_circ_0004085. RESULTS: First, we screened out hsa_circ_0004085 with abnormally high expression in CRC clinical samples infected with Fn and found that patients with high expression of hsa_circ_0004085 in plasma had a poor clinical response to oxaliplatin/5-FU. Subsequently, the circular structure of hsa_circ_0004085 was identified. Fn infection promoted hsa_circ_0004085 formation by hnRNP L and packaged hsa_circ_0004085 into exosomes by hnRNP A1. Exosomes produced by Fn-infected CRC cells transferred hsa_circ_0004085 between cells and delivered oxaliplatin/5-FU resistance to recipient cells by relieving ER stress. Hsa_circ_0004085 enhanced the stability of GRP78 mRNA by binding to RRBP1 and promoted the nuclear translocation of ATF6p50 to relieve ER stress. CONCLUSIONS: Plasma levels of hsa_circ_0004085 are increased in colon cancer patients with intracellular Fn and are associated with a poor response to oxaliplatin/5-FU. Fn infection promoted hsa_circ_0004085 formation by hnRNP L and packaged hsa_circ_0004085 into exosomes by hnRNP A1. Exosomes secreted by Fn-infected CRC cells deliver hsa_circ_0004085 between cells. Hsa_circ_0004085 relieves ER stress in recipient cells by regulating GRP78 and ATF6p50, thereby delivering resistance to oxaliplatin and 5-FU.

Fusobacterium nucleatum promotes tumor progression in KRAS p.G12D-mutant colorectal cancer by binding to DHX15.

Fusobacterium nucleatum (F. nucleatum) promotes intestinal tumor growth and its relative abundance varies greatly among patients with CRC, suggesting the presence of unknown, individual-specific effectors in F. nucleatum-dependent carcinogenesis. Here, we identify that F. nucleatum is enriched preferentially in KRAS p.G12D mutant CRC tumor tissues and contributes to colorectal tumorigenesis in Villin-Cre/KrasG12D+/- mice. Additionally, Parabacteroides distasonis (P. distasonis) competes with F. nucleatum in the G12D mouse model and human CRC tissues with the KRAS mutation. Orally gavaged P. distasonis in mice alleviates the F. nucleatum-dependent CRC progression. F. nucleatum invades intestinal epithelial cells and binds to DHX15, a protein of RNA helicase family expressed on CRC tumor cells, mechanistically involving ERK/STAT3 signaling. Knock out of Dhx15 in Villin-Cre/KrasG12D+/- mice attenuates the CRC phenotype. These findings reveal that the oncogenic effect of F. nucleatum depends on somatic genetics and gut microbial ecology and indicate that personalized modulation of the gut microbiota may provide a more targeted strategy for CRC treatment.

A global survey of small RNA interactors identifies KhpA and KhpB as major RNA-binding proteins in Fusobacterium nucleatum.

The common oral microbe Fusobacterium nucleatum has recently drawn attention after it was found to colonize tumors throughout the human body. Fusobacteria are also interesting study systems for bacterial RNA biology as these early-branching species encode many small noncoding RNAs (sRNAs) but lack homologs of the common RNA-binding proteins (RBPs) CsrA, Hfq and ProQ. To search for alternate sRNA-associated RBPs in F. nucleatum, we performed a systematic mass spectrometry analysis of proteins that co-purified with 19 different sRNAs. This approach revealed strong enrichment of the KH domain proteins KhpA and KhpB with nearly all tested sRNAs, including the σE-dependent sRNA FoxI, a regulator of several envelope proteins. KhpA/B act as a dimer to bind sRNAs with low micromolar affinity and influence the stability of several of their target transcripts. Transcriptome studies combined with biochemical and genetic analyses suggest that KhpA/B have several physiological functions, including being required for ethanolamine utilization. Our RBP search and the discovery of KhpA/B as major RBPs in F. nucleatum are important first steps in identifying key players of post-transcriptional control at the root of the bacterial phylogenetic tree.

Interspecies metabolite transfer fuels the methionine metabolism of Fusobacterium nucleatum to stimulate volatile methyl mercaptan production.

The major oral odor compound methyl mercaptan (CH3SH) is strongly associated with halitosis and periodontitis. CH3SH production stems from the metabolism of polymicrobial communities in periodontal pockets and on the tongue dorsum. However, understanding of CH3SH-producing oral bacteria and their interactions is limited. This study aimed to investigate CH3SH production by major oral bacteria and the impact of interspecies interactions on its generation. Using a newly constructed large-volume anaerobic noncontact coculture system, Fusobacterium nucleatum was found to be a potent producer of CH3SH, with that production stimulated by metabolic interactions with Streptococcus gordonii, an early dental plaque colonizer. Furthermore, analysis of extracellular amino acids using an S. gordonii arginine-ornithine antiporter (ArcD) mutant demonstrated that ornithine excreted from S. gordonii is a key contributor to increased CH3SH production by F. nucleatum. Further study with 13C, 15N-methionine, as well as gene expression analysis, revealed that ornithine secreted by S. gordonii increased the demand for methionine through accelerated polyamine synthesis by F. nucleatum, leading to elevated methionine pathway activity and CH3SH production. Collectively, these findings suggest that interaction between S. gordonii and F. nucleatum plays a key role in CH3SH production, providing a new insight into the mechanism of CH3SH generation in oral microbial communities. A better understanding of the underlying interactions among oral bacteria involved in CH3SH generation can lead to the development of more appropriate prophylactic approaches to treat halitosis and periodontitis. An intervention approach like selectively disrupting this interspecies network could also offer a powerful therapeutic strategy.IMPORTANCEHalitosis can have a significant impact on the social life of affected individuals. Among oral odor compounds, CH3SH has a low olfactory threshold and halitosis is a result of its production. Recently, there has been a growing interest in the collective properties of oral polymicrobial communities, regarded as important for the development of oral diseases, which are shaped by physical and metabolic interactions among community participants. However, it has yet to be investigated whether interspecies interactions have an impact on the production of volatile compounds, leading to the development of halitosis. The present findings provide mechanistic insights indicating that ornithine, a metabolite excreted by Streptococcus gordonii, promotes polyamine synthesis by Fusobacterium nucleatum, resulting in a compensatory increase in demand for methionine, which results in elevated methionine pathway activity and CH3SH production. Elucidation of the mechanisms related to CH3SH production is expected to lead to the development of new strategies for managing halitosis.

Association of Fusobacterium nucleatum infection with the clinicopathological characteristics in colorectal cancer patients.

BACKGROUND: Colorectal cancer (CRC) is a global health problem. The gut microbiome is now recognized as an important underlying factor to the initiation and progression of CRC. Fusobacterium nucleatum (FN) is one of the most studied bacteria in the aetiology of CRC. This study provided cohort evidence on the association of FN infection with clinicopathologic features in CRC patients. METHODS: We analysed the cancerous and adjacent non-cancerous formalin-fixed paraffin embedded (FFPE) tissue of 83 CRC patients from a single medical centre in Malaysia. TaqMan probe-based qPCR targeting the 16S rRNA gene was used to detect the presence of FN in the extracted FFPE DNA. The differences in FN expression between cancer and non-cancer tissues were evaluated. Association studies between FN infection in the tumour and relative FN abundance with available clinical data were conducted. RESULTS: FN was more abundant in the cancerous tissue compared to non-cancerous tissue (p = 0.0025). FN infection in the tumour was significantly associated with lymph node metastasis (p = 0.047) and cancer staging (p = 0.032), but not with other clinicopathologic variables. In double-positive patients where FN was detected in both cancerous and non-cancerous tissue, the expression fold-change of FN, calculated using 2-ΔΔCT formula, was significantly higher in patients with tumour size equal to or greater than 5 cm (p = 0.033) and in KRAS-mutated patients (p = 0.046). CONCLUSIONS: FN is enriched in CRC tumour tissue and is associated with tumour size, lymph node metastasis, cancer staging, and KRAS mutation in this single-centre small cohort study.

Intratumoral presence of the genotoxic gut bacteria pks+ E. coli, Enterotoxigenic Bacteroides fragilis, and Fusobacterium nucleatum and their association with clinicopathological and molecular features of colorectal cancer.

BACKGROUND: This study aimed to investigate clinicopathological and molecular tumour features associated with intratumoral pks+ Escherichia coli (pks+E.coli+), pks+E.coli- (non-E.coli bacteria harbouring the pks island), Enterotoxigenic Bacteroides fragilis (ETBF) and Fusobacterium nucleatum (F. nucleatum). METHODS: We screened 1697 tumour-derived DNA samples from the Australasian Colorectal Cancer Family Registry, Melbourne Collaborative Cohort Study and the ANGELS study using targeted PCR. RESULTS: Pks+E.coli+ was associated with male sex (P < 0.01) and APC:c.835-8 A > G somatic mutation (P = 0.03). The association between pks+E.coli+ and APC:c.835-8 A > G was specific to early-onset CRCs (diagnosed<45years, P = 0.02). The APC:c.835-A > G was not associated with pks+E.coli- (P = 0.36). F. nucleatum was associated with DNA mismatch repair deficiency (MMRd), BRAF:c.1799T>A p.V600E mutation, CpG island methylator phenotype, proximal tumour location, and high levels of tumour infiltrating lymphocytes (Ps < 0.01). In the stratified analysis by MMRd subgroups, F. nucleatum was associated with Lynch syndrome, MLH1 methylated and double MMR somatic mutated MMRd subgroups (Ps < 0.01). CONCLUSION: Intratumoral pks+E.coli+ but not pks+E.coli- are associated with CRCs harbouring the APC:c.835-8 A > G somatic mutation, suggesting that this mutation is specifically related to DNA damage from colibactin-producing E.coli exposures. F. nucleatum was associated with both hereditary and sporadic MMRd subtypes, suggesting the MMRd tumour microenvironment is important for F. nucleatum colonisation irrespective of its cause.

Fusobacterium nucleatum exacerbates the progression of pulpitis by regulating the STING-dependent pathway.

Bacterial infection is the main cause of pulpitis. However, whether a dominant bacteria can promote the progression of pulpitis and its underlying mechanism remains unclear. We provided a comprehensive assessment of the microbiota alteration in pulpitis using 16S rRNA sequencing. Fusobacterium nucleatum was the most enriched in pulpitis and played a pathogenic role accelerating pulpitis progression in rat pulpitis model. After odontoblast-like cells cocultured with F. nucleatum, the stimulator of interferon genes (STING) pathway and autophagy were activation. There was a float of STING expression during F. nucleatum stimulation. STING was degraded by autophagy at the early stage. At the late stage, F. nucleatum stimulated mitochondrial Reactive Oxygen Species (ROS) production, mitochondrial dysfunction and then mtDNA escape into cytosol. mtDNA, which escaped into cytosol, caused more cytosolic mtDNA binds to cyclic GMP-AMP synthase (cGAS). The release of IFN-ß was dramatically reduced when mtDNA-cGAS-STING pathway inhibited. STING-/- mice showed milder periapical bone loss and lower serum IFN-ß levels compared with wildtype mice after 28 days F. nucleatum-infected pulpitis model establishment. Our data demonstrated that F. nucleatum exacerbated the progression of pulpitis, which was mediated by the STING-dependent pathway.

Bacterial diversity in primary infected root canals of a Chinese cohort: analysis of 16 S rDNA sequencing.

PURPOSE: To characterize the bacterial community in the primarily infected root canals. METHODS: A total of 13 samples were collected from the primarily infected root canals. 16 S rDNA sequencing was performed to define bacterial community. Taxonomic annotation, bacterial hierarchical structures, community richness and diversity, and inter-subject variability of the bacterial community in the root canal samples were analyzed. Gender, age, and duration of the toothache-specific bacterial community associated with the patient groups were analyzed. RESULTS: A total of 359 Species were annotated and identified in the whole study cohort. The Alpha diversity analysis showed that the species diversity and detection rate of the 13 samples were high, which reflected the authenticity of sequencing results. The Beta diversity analysis was used to compare the degree of difference between different root canal samples. The 13 samples were divided into two groups according to the results, group A was samples I1-I12, and group B was samples I13. The bacterial species of group A samples were analyzed with the clinical characteristics of patients, and it was found that gender, and duration specific differences in bacterial species, and there was no significant difference in species types among different ages of patients. CONCLUSION: There were a wide diversity and inter-subject variability in the bacterial community in the primary infected root canals. While Porphyromonas gingivalis was the most abundant species, Fusobacterium nucleatum was the most variable species in the bacterial community of the root canal. The bacterial community at different taxonomic levels varied from sample to sample, despite consistent disease diagnoses. There was gender, duration-specific differences in the bacterial species in the primary infected root canals.

Effects of metronidazole on colorectal cancer occurrence and colorectal cancer liver metastases by regulating Fusobacterium nucleatum in mice.

OBJECTIVE: Colorectal cancer (CRC) represents a leading cause of cancer-related deaths. Metronidazole (MNZ) is exceedingly implicated in CRC. This study explored the roles of MNZ in mouse CRC occurrence and liver metastasis (CRLM). METHODS: Male BALB/c nude mice were subjected to CRC and CRLM modeling, orally administration with MNZ (1 g/L) 1 week before modeling, and disease activity index (DAI) evaluation. Fresh stool and anal swab samples were collected on the morning of the 28th day after modeling. The relative expression of Fusobacterium nucleatum (F. nucleatum) DNA was assessed by quantitative polymerase chain reaction. After euthanasia, tumor tissues and liver tissues were separated and the tumor volume and weight change were measured. The liver tissues were stained with hematoxylin-eosin to quantitatively analyze the metastatic liver nodules. Malignant tumor biomarker Ki67 protein levels in liver tissues/DNA from stool samples were detected by immunohistochemistry/high-throughput 16S rRNA gene sequencing. Bioinformatics analysis was performed on the raw sequence data to analyze microbial community richness (Chao1 index, ACE index) and microbial community diversity (Shannon index). RESULTS: The DAI and F. nucleatum DNA relative expression in feces and anal swabs of the CRC and CRLM groups were raised and repressed after MNZ intervention. MNZ repressed tumor occurrence and growth in mice to a certain extent, alleviated CRLM malignant degree (reduced liver metastases and Ki67-positive cell density/number), and suppressed CRC liver metastasis by regulating intestinal flora structure, which affected the intestinal characteristic flora of CRC and CRLM mice. CONCLUSION: MNZ suppressed CRC occurrence and CRLM in mice by regulating intestinal F. nucleatum.

Fusobacterium nucleatum facilitates proliferation and autophagy by activating miR-361-3p/NUDT1 axis through oxidative stress in hypopharyngeal squamous cell carcinoma.

BACKGROUND: To investigate how Fusobacterium nucleatum (Fn) promotes oxidative stress and mediates proliferation and autophagy in hypopharyngeal squamous cell carcinoma (HPSCC). METHODS: The prognosis for 82 HPSCC cases was retrospectively analyzed. HPSCC cell line FaDu was co-cultured with Fn. Knockdown of NUDT1 (shNUDT1 group) was done after observing DNA damage response. CCK8 and tumorigenesis assays for proliferation observation, mitochondria ROS (MitoROS) measurement to examine intracellular oxidative stress, and ELISA to analyze concentration of 8-oxo-2'-deoxyguanosine (8-oxo-dG) in cells. Dual-luciferase reporter assays clarified miR-361-3p connection with NUDT1. Autophagy flow was observed using electron microscopy and related proteins. RESULTS: Fn was highly associated with NUDT1. The shNUDT1 group experienced lower proliferation compared with normal FaDu (NC group) in vivo and in vitro. The shNUDT1 group showed 8-oxo-dG and γH2AX to be elevated. Intracellular ROS decreased in shNUDT1Fn group when compared to Fn group. Upregulating miR-361-3p could suppress NUDT1 expression and downstream proliferation and autophagy. Fn modulated miR-361-3p via OH-, which could be proven by H2O2 assay and N-acetylcysteine. CONCLUSIONS: Higher Fn in HPSCC patients suggests poorer prognosis. NUDT1 might affect cell proliferation and autophagy and modulate DNA damage response. The oxidative stress induced miR-361-3p/NUDT1 axis is first introduced in microbiome-carcinoma research.

[Advances on the treatment of Fusobacterium nucleatum-promoted colorectal cancers using nanomaterials].

Fusobacterium nucleatum (Fn) is an oral anaerobic bacterium that has recently been found to colonize on the surface of colorectal cancer cells in humans, and its degree of enrichment is highly negatively correlated with the prognosis of tumor treatment. Numerous studies have shown that Fn is involved in the occurrence and development of colorectal cancer (CRC), and Fn interacts with multiple components in the tumor microenvironment to increase tumor resistance. In recent years, researchers have begun using nanomedicine to inhibit Fn's proliferation at the tumor site or directly target Fn to treat CRC. This review summarizes the mechanism of Fn in promoting CRC and the latest research progress on Fn-related CRC therapy using different nanomaterials. Finally, the applications perspective of nanomaterials in Fn-promoted CRC therapy was prospected.

Strain-level detection of Fusobacterium nucleatum in colorectal cancer specimens by targeting the CRISPR-Cas region.

IMPORTANCE: Fusobacterium nucleatum is one of the predominant oral bacteria in humans. However, this bacterium is enriched in colorectal cancer (CRC) tissues and may be involved in CRC development. Our previous research suggested that F. nucleatum is present in CRC tissues originating from the oral cavity using a traditional strain-typing method [arbitrarily primed polymerase chain reaction (AP-PCR)]. First, using whole-genome sequencing, this study confirmed an exemplary similarity between the oral and tumoral strains derived from each patient with CRC. Second, we successfully developed a method to genotype this bacterium at the strain level, targeting the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated system, which is hypervariable (defined as F. nucleatum-strain genotyping PCR). This method can identify F. nucleatum strains in cryopreserved samples and is significantly superior to traditional AP-PCR, which can only be performed on isolates. The new methods have great potential for application in etiological studies of F. nucleatum in CRC.

Fusobacterium nucleatum upregulates MMP7 to promote metastasis-related characteristics of colorectal cancer cell via activating MAPK(JNK)-AP1 axis.

BACKGROUND: Colorectal cancer (CRC) is the third most common malignant tumor. Fusobacterium nucleatum (F. nucleatum) is overabundant in CRC and associated with metastasis, but the role of F. nucleatum in CRC cell migration and metastasis has not been fully elucidated. METHODS: Differential gene analysis, protein-protein interaction, robust rank aggregation analysis, functional enrichment analysis, and gene set variation analysis were used to figure out the potential vital genes and biological functions affected by F. nucleatum infection. The 16S rDNA sequencing and q-PCR were used to detect the abundance of F. nucleatum in tissues and stools. Then, we assessed the effect of F. nucleatum on CRC cell migration by wound healing and transwell assays, and confirmed the role of Matrix metalloproteinase 7 (MMP7) induced by F. nucleatum in cell migration. Furthermore, we dissected the mechanisms involved in F. nucleatum induced MMP7 expression. We also investigated the MMP7 expression in clinical samples and its correlation with prognosis in CRC patients. Finally, we screened out potential small molecular drugs that targeted MMP7 using the HERB database and molecular docking. RESULTS: F. nucleatum infection altered the gene expression profile and affected immune response, inflammation, biosynthesis, metabolism, adhesion and motility related biological functions in CRC. F. nucleatum was enriched in CRC and promoted the migration of CRC cell by upregulating MMP7 in vitro. MMP7 expression induced by F. nucleatum infection was mediated by the MAPK(JNK)-AP1 axis. MMP7 was highly expressed in CRC and correlated with CMS4 and poor clinical prognosis. Small molecular drugs such as δ-tocotrienol, 3,4-benzopyrene, tea polyphenols, and gallic catechin served as potential targeted therapeutic drugs for F. nucleatum induced MMP7 in CRC. CONCLUSIONS: Our study showed that F. nucleatum promoted metastasis-related characteristics of CRC cell by upregulating MMP7 via MAPK(JNK)-AP1 axis. F. nucleatum and MMP7 may serve as potential therapeutic targets for repressing CRC advance and metastasis.