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Considerable resources are being used to study associations between the human microbiota and malignancy. There is a particular interest in the connection between Fusobacterium animalis and colorectal cancer. In this paper, we correct recent taxonomic misconceptions of importance to this research and critically reassess proposed gene candidates for explaining F. animalis pathogenicity. We demonstrate the importance of strict adherence to taxonomic rules when discovering possibly novel phylogenetic groups and emphasize that genome references are still not available for all known bacteria. We reassess the phylogeny of the medically important Fusobacterium nucleatum group including F. animalis using contemporary approaches, provide a genome reference for Fusobacterium watanabei, and describe Fusobacterium paranimalis sp. nov. Our results dispute the concept of using a single closely related comparator phylogenetic group when searching for candidate genes potentially explaining species-specific pathogenicity and show that such comparative approaches can only be meaningful when all relevant related species are included.

Background Schistosomiasis is a neglected tropical disease burdening millions of people. One drug, praziquantel, is currently used for treatment and control. Clinically relevant drug resistance has not yet been described, but there is considerable heterogeneity in treatment outcomes, ranging from cure to only moderate egg reduction rates. The objectives of this study are to investigate potential worm-induced dysbacteriosis of the gut microbiota and to assess whether a specific microbiome profile could influence praziquantel response. Methods Using V3 and V4 regions of 16S rRNA genes, we screened the gut microbiota of 34 Schistosoma mansoni infected and uninfected children from Côte d’Ivoire. From each infected child one pre-treatment, one 24-hour and one 21-day follow-up sample after administering 60 mg/kg praziquantel or placebo, were collected. Results Overall taxonomic profiling and diversity indicators were found to be close to a “healthy” gut structure in all children. Slight overall compositional changes were observed between S. mansoni -infected and non-infected children. Praziquantel treatment was not linked to a major shift in the gut taxonomic profiles, thus reinforcing the good safety profile of the drug by ruling out off-targets effects on the gut microbes. 16S rRNA gene of the Fusobacteriales order was significantly more abundant in cured individuals, both at baseline and 24 hours post-treatment. A real-time qPCR confirmed the over-abundance of Fusobacterium spp. in cured children. Fusobacterium spp. abundance could also be correlated with treatment induced S. mansoni egg-reduction. Conclusions Our study suggests that neither a S. mansoni infection nor praziquantel administration triggers a significant effect on the microbial composition and that a higher abundance of Fusobacterium spp., before treatment, is associated with higher efficacy of praziquantel in the treatment of S. mansoni infections. Trial registration International Standard Randomised Controlled Trial, number ISRCTN15280205 .

The bacterial genus Fusobacterium promotes colorectal cancer (CRC) development, but an understanding of its precise composition at the species level in the human gut and the relevant association with CRC is lacking. Herein, we devise a Fusobacterium rpoB amplicon sequencing (FrpoB-seq) method that enables the differentiation of Fusobacterium species and certain subspecies in the microbiota. By applying this method to clinical tissue and faecal samples from CRC patients, we detect 62 Fusobacterium species, including 45 that were previously undescribed. We additionally reveal that Fusobacterium species may display different lineage-dependent functions in CRC. Specifically, a lineage (designated L1) including F. nucleatum , F. hwasookii , F. periodonticum and their relatives (rather than any particular species alone) is overabundant in tumour samples and faeces from CRC patients, whereas a non-enriched lineage (designated L5) represented by F. varium and F. ulcerans in tumours has a positive association with lymphovascular invasion. Bacteria from the genus Fusobacterium can promote colorectal cancer (CRC) development; however, the exact Fusobacterium species involved in this process remain underexplored. Here, the authors develop a rpoB amplicon sequencing approach to identify Fusobacterium species and subspecies in CRC patient samples.

Fusobacterium nucleatum (Fn) is increasingly recognized as a cancer-associated bacterium, yet reliable quantification in human specimens is challenging due to low bacterial burden and abundant host DNA. We analyzed 145 Fusobacterium genomes to design primers targeting conserved regions of the fadA adhesin gene and developed a duplex quantitative real-time PCR (qPCR) assay for simultaneous detection of fadA and a human PGT as an internal control. Analytical sensitivity, specificity, precision, and reproducibility were evaluated using serially diluted Fn DNA, spike-in experiments with human DNA, and cross-platform/operator validation. Clinical performance was assessed in colorectal cancer patient tissues, including fresh tissue (n = 24) and formalin-fixed paraffin-embedded (FFPE) samples (n = 22), using 16S rRNA-based methods as references. The assay successfully detected all four major Fn subspecies (nucleatum, animalis, polymorphum, and vincentii). The limit of detection was ≤0.1 pg, with no interference between duplex targets. Spike-in experiments demonstrated consistent target detection in human-DNA-rich samples, with strong linearity (R2 = 0.998) across dilutions. High precision (coefficient of variations < 5%) was observed across intra-day, inter-day, inter-instrument, and inter-operator evaluations. In fresh tissues, the assay yielded 86% sensitivity, 94% specificity, and 92% accuracy. Using the FFPE samples, the assay achieved 91% sensitivity and 100% specificity, confirming robust classification in both clinical samples. This duplex qPCR assay enables broad detection of Fn with high analytical performance in both fresh and FFPE tissues. Its simplicity, reproducibility, and compatibility with pathology workflows support deployment in multi-center studies and downstream applications in diagnostic studies and prognostic modeling.

Previous work has demonstrated that intestinal bacteria, such as Fusobacterium varium (F. varium), contribute to the clinical activity in ulcerative colitis (UC); thus, an antibiotic combination therapy (amoxicillin, tetracycline, and metronidazole (ATM)) against F. varium can induce and maintain UC remission. Therefore, we investigated whether ATM therapy induces a long-term alteration of intestinal microbiota in patients with UC. Patients with UC were enrolled in a multicenter, randomized, double-blind, placebo-controlled study. Biopsy samples at the beginning of the trial and again at 3 months after treatment completion were randomly obtained from 20 patients. The terminal restriction fragment length polymorphism (T-RFLP) in mucosa-associated bacterial components was examined to assess the alteration of the intestinal microbiota. Profile changes of T-RFLP in mucosa-associated bacterial components were found in 10 of 12 patients in the treatment group and in none of 8 in the placebo group. Dice similarity coefficients using the unweighted pair group method with arithmetic averages (Dice-UPGMA) confirmed that the similarity of mucosal microbiota from the descending colon was significantly decreased after the ATM therapy, and this change was maintained for at least 3 months. Moreover, at 3 months after treatment completion, the F. varium/β-actin ratio, examined by real-time PCR using nested PCR products from biopsy samples, was reduced less than 40% in 8 of 12 treated patients, which was higher, but not significantly, than in 4 of 8 patients in the placebo group. Together, these results suggest that ATM therapy induces long-term alterations in the intestinal microbiota of patients with UC, which may be associated, at least in part, with clinical effects of the therapy.

This study explores and verifies potential molecular targets through which KRAS mutations regulate the colonization of Fusobacterium nucleatum (FN) in colorectal cancer (CRC). This study combined multiple bioinformatics methods and biological assays. Through The Cancer Genome Atlas, Gene Expression Omnibus, Human Protein Atlas, immunohistochemistry, and co‐culture assays, we further confirmed the differential expression of SERTAD4 in CRC. We delved deeper into examining how expression of SERTAD4 is linked with immune cell infiltration and the enrichment of potential pathways. Lastly, through bacterial phenotypic assays, we validated the function of SERTAD4. As a molecule associated with KRAS mutations and FN infection, the expression levels of SERTAD4 were downregulated in CRC. The diagnostic efficacy of SERTAD4 for CRC is not inferior to that of CEA. Low expression of SERTAD4 is associated with poorer overall survival in CRC. Correlation analysis found that increased expression of SERTAD4 is associated with various immune cell infiltrations and immune checkpoint genes. Finally, bacterial adhesion and invasion assays verify that SERTAD4 inhibits the adhesion and invasion abilities of FN in CRC. This study demonstrates that SERTAD4 exerts a protective role in CRC by inhibiting the colonization of FN.

Non -nucleatum Fusobacterium may play a nonnegligible role in colorectal cancer (CRC) and certain Fusobacterium lineages (namely, L1 and L5) have shown specific associations with CRC. We aim to clarify the complex connections between Fusobacterium and CRC. We found that the widely adopted quantitative PCR (qPCR) method could overestimate F. nucleatum abundance and, in fact, reflect L1 levels in clinical samples. A lineage-specific qPCR assay targeting L1/L5 was developed and validated using mock and clinical samples. Its application in independent cohorts confirmed that L1 was overabundant in CRC, whereas L5 correlated with lymphovascular invasion. Importantly, faecal L1 abundance was more predictive of CRC than F. nucleatum , supported also by cross-population metagenomic data. CRC-associated virulence and colonisation genes were found in various L1 species other than F. nucleatum . Our results highlight the clinical importance of L1/L5 in CRC with high-diversity Fusobacterium contexts and suggest that non- nucleatum Fusobacterium may also contribute to CRC.

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. Multiomic study reveals that tumor microenvironmental factors such as hypoxia influence intracellular infection of Fusobacterium nucleatum in colorectal cancer cells and provides clues to malignant transformation of infected cells.

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. 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 .

Fusobacteria have been associated to different diseases, including colorectal cancer (CRC), but knowledge of which taxonomic groups contribute to specific conditions is incomplete. We analyzed the genetic diversity and relationships within the Fusobacterium genus. We report recent and ancestral recombination in core genes, indicating that fusobacteria have mosaic genomes and emphasizing that taxonomic demarcation should not rely on single genes/gene regions. Across databases, we found ample evidence of species miss-classification and of undescribed species, which are both expected to complicate disease association. By focusing on a lineage that includes F. periodonticum/pseudoperiodonticum and F. nucleatum , we show that genomes belong to four modern populations, but most known species/subspecies emerged from individual ancestral populations. Of these, the F. periodonticum/pseudoperiodonticum population experienced the lowest drift and displays the highest genetic diversity, in line with the less specialized distribution of these bacteria in oral sites. A highly drifted ancestral population instead contributed genetic ancestry to a new species, which includes genomes classified within the F. nucleatum animalis diversity in a recent CRC study. Thus, evidence herein calls for further evolutionary and phylogenomic analyses based on more Flavobacterium nucleatum genome sequences. More generally, our data inform future molecular profiling approaches to investigate the epidemiology of Fusobacterium -associated diseases. Parsing the genetic diversity within the Fusobacterium genus provides ample evidence of species miss-classification and of undescribed species, and calls for a re-analysis of F. nucleatum features associated to colorectal cancer.