Project description:Fusobacterium nucleatum, one of the major causative bacteria of periodontitis, is classified into five subspecies (nucleatum, polymorphum, vincentii, animalis, and fusiforme) on the basis of the several phenotypic characteristics and DNA homology. This is the first report of the draft genome sequence of F. nucleatum subsp. fusiforme ATCC 51190(T).
Project description:An estimated 15% or more of the cancer burden worldwide is attributable to known infectious agents. We screened colorectal carcinoma and matched normal tissue specimens using RNA-seq followed by host sequence subtraction and found marked over-representation of Fusobacterium nucleatum sequences in tumors relative to control specimens. F. nucleatum is an invasive anaerobe that has been linked previously to periodontitis and appendicitis, but not to cancer. Fusobacteria are rare constituents of the fecal microbiota, but have been cultured previously from biopsies of inflamed gut mucosa. We obtained a Fusobacterium isolate from a frozen tumor specimen; this showed highest sequence similarity to a known gut mucosa isolate and was confirmed to be invasive. We verified overabundance of Fusobacterium sequences in tumor versus matched normal control tissue by quantitative PCR analysis from a total of 99 subjects (p = 2.5 × 10(-6)), and we observed a positive association with lymph node metastasis.
Project description:Accumulating evidence links colorectal cancer (CRC) with the intestinal microbiota. However, the disturbance of intestinal microbiota and the role of Fusobacterium nucleatum during the colorectal adenoma-carcinoma sequence have not yet been evaluated.454 FLX pyrosequencing was used to evaluate the disturbance of intestinal microbiota during the adenoma-carcinoma sequence pathway of CRC. Intestinal microbiota and mucosa tumor-immune cytokines were detected in mice after introducing 1,2-dimethylhydrazine (DMH), F. nucleatum or Berberine (BBR), using pyrosequencing and Bio-Plex Pro™ cytokine assays, respectively. Protein expressions were detected by western blotting.The levels of opportunistic pathogens, such as Fusobacterium, Streptococcus and Enterococcus spp. gradually increased during the colorectal adenoma-carcinoma sequence in human fecal and mucosal samples. F. nucleatum treatment significantly altered lumen microbial structures, with increased Tenericutes and Verrucomicrobia (opportunistic pathogens) (P < 0.05 = in wild-type C57BL/6 and mice with DMH treatment). BBR intervention reversed the F. nucleatum-mediated increase in opportunistic pathogens, and the secretion of IL-21/22/31, CD40L and the expression of p-STAT3, p-STAT5 and p-ERK1/2 in mice, compared with mice fed with F. nucleatum alone.F. nucleatum colonization in the intestine may prompt colorectal tumorigenesis. BBR could rescue F. nucleatum-induced colorectal tumorigenesis by modulating the tumor microenvironment and blocking the activation of tumorigenesis-related pathways.
Project description:Fusobacterium nucleatum is considered to be a key oral bacterium in recruiting periodontal pathogens into subgingival dental plaque. Currently F. nucleatum can be subdivided into five subspecies. Our previous genome analysis of F. nucleatum W1481 (referred to hereafter as W1481), isolated from an 8-mm periodontal pocket in a patient with chronic periodontitis, suggested the possibility of a new subspecies. To further investigate the biology and relationships of this possible subspecies with other known subspecies, we performed comparative analysis between W1481 and 35 genome sequences represented by the five known Fusobacterium subspecies. Our analyses suggest that W1481 is most likely a new F. nucleatum subspecies, supported by evidence from phylogenetic analyses and maximal unique match indices (MUMi). Interestingly, we found a horizontally transferred W1481-specific genomic island harboring the tripartite ATP-independent (TRAP)-like transporter genes, suggesting this bacterium might have a high-affinity transport system for the C4-dicarboxylates malate, succinate, and fumarate. Moreover, we found virulence genes in the W1481 genome that may provide a strong defense mechanism which might enable it to colonize and survive within the host by evading immune surveillance. This comparative study provides better understanding of F. nucleatum and the basis for future functional work on this important pathogen.
Project description:Three native plasmids of Fusobacterium nucleatum were characterized, including DNA sequence analysis of one plasmid, pFN1. A shuttle plasmid, pHS17, capable of transforming Escherichia coli and F. nucleatum ATCC 10953 was constructed with pFN1. pHS17 was stably maintained in the F. nucleatum transformants, and differences in the transformation efficiencies suggested the presence of a restriction-modification system in F. nucleatum.
Project description:Fusobacterium nucleatum-treated LoVo cells reported an increased promoting CRC metastasis effect compared with PBS control. To understand the underlying mechanisms of Fusobacterium nucleatum-induced metastasis ability of CRC cells, we performed RNA-sequencing in LoVo cells s with or without Fusobacterium nucleatum treatment with three independent biological replicates. Overall design: Examination of gene expression variation in LoVo cells treated with or without Fusobacterium nucleatum (MOI of 100:1)
Project description:Fusobacterium nucleatum has long been found to cause opportunistic infections and has recently been implicated in colorectal cancer; however, it is a common member of the oral microbiota and can have a symbiotic relationship with its hosts. To address this dissonance, we explore the diversity and niches of fusobacteria and reconsider historic fusobacterial taxonomy in the context of current technology. We also undertake a critical reappraisal of fusobacteria with a focus on F. nucleatum as a mutualist, infectious agent and oncogenic microorganism. In this Review, we delve into recent insights and future directions for fusobacterial research, including the current genetic toolkit, our evolving understanding of its mechanistic role in promoting colorectal cancer and the challenges of developing diagnostics and therapeutics for F. nucleatum.
Project description:Colorectal cancer (CRC) is the third most prevalent cancer and second in terms of mortality. Emerging evidence from recent studies suggests a potential role of Fusobacterium nucleatum in the development of CRC. In this article, we review studies from different geographical regions examining the association between F. nucleatum and CRC, the detection methods and the tumorigenic mechanisms. Furthermore, we discuss the potential clinical impact of F. nucleatum in CRC and suggest future study directions.
Project description:Background: Microbial dysbiosis is closely associated with visceral hypersensitivity and is involved in the pathogenesis of irritable bowel syndrome (IBS), but the specific strains that play a key role have yet to be identified. Previous bioinformatic studies have demonstrated that Fusobacterium is a shared microbial feature between IBS patients and maternal separation (MS)-stressed rats. In this study, we assessed the potential role of Fusobacterium nucleatum (F. nucleatum) in the pathogenesis of IBS. Methods: Fecal samples of patients with diarrhea predominant-IBS (IBS-D) and healthy controls were obtained. An MS rat model was established to receive gavage of either F. nucleatum or normal saline. Visceral sensitivity was evaluated through colorectal distension test, and fecal microbiota was analyzed by 16S rRNA gene sequencing. F. nucleatum-specific IgA levels in fecal supernatants were assessed by western blotting. The antigen reacted with the specific IgA of F. nucleatum was identified by mass spectrometry and the construction of a recombinant Escherichia coli BL21 (DE3). Results: IBS-D patients showed a lower Shannon index and a higher abundance of Fusobacterium. The F. nucleatum-gavage was shown to exacerbate visceral hypersensitivity in MS rats, with both the F. nucleatum-gavage and MS causing a decreased Shannon index and a clear segregation of fecal microbiota. In addition, specific IgA against F. nucleatum was detected in fecal supernatants of both the F. nucleatum-gavaged rats and the IBS-D patients. The FomA protein, which is a major outer membrane protein of F. nucleatum, was confirmed to react with the specific IgA of F. nucleatum in fecal supernatants. Conclusion: Fusobacterium increased significantly in IBS-D patients, and F. nucleatum was involved in the pathogenesis of IBS by causing microbial dysbiosis and exacerbating visceral hypersensitivity in a colonization-independent manner. Meanwhile, F. nucleatum was found to induce an increase in specific secretory IgA through FomA.