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PubMed2004

Modulation of the antibody response by Porphyromonas gingivalis and Fusobacterium nucleatum in a mouse model.

Successive immunization of mice with Fusobacterium nucleatum and Porphyromonas gingivalis has been shown to modulate the specific serum IgG responses to these organisms. The aim of this study was to investigate these antibody responses further by examining the IgG subclasses induced as well as the opsonizing properties of the specific antibodies. Serum samples from BALB/c mice immunized with F. nucleatum (gp1-F), P. gingivalis (gp2-P), P. gingivalis followed by F. nucleatum (gp3-PF) F. nucleatum followed by P. gingivalis (gp4-FP) or saline alone (gp5-S) were examined for specific IgG1 (Th2) and IgG2a (Th1) antibody levels using an ELISA and the opsonizing properties measured using a neutrophil chemiluminescence assay. While IgG1 and IgG2a subclasses were induced in all immunized groups, there was a tendency towards an IgG1 response in mice immunized with P. gingivalis alone, while immunization with F. nucleatum followed by P. gingivalis induced significantly higher anti-P. gingivalis IgG2a levels than IgG1. The maximum light output due to neutrophil phagocytosis of P. gingivalis occurred at 10 min using nonopsonized bacteria. Chemiluminescence was reduced using serum-opsonized P. gingivalis and, in particular, sera from P. gingivalis-immunized mice (gp2-P), with maximum responses occurring at 40 min. In contrast, phagocytosis of immune serum-opsonized F. nucleatum demonstrated peak light output at 10 min, while that of F. nucleatum opsonized with sera from saline injected mice (gp5-S) and control nonopsonized bacteria showed peak responses at 40 min. The lowest phagocytic response occurred using gp4-FP serum-opsonized F. nucleatum. In conclusion, the results of the present study have demonstrated a systemic Th1/Th2 response in mice immunized with P. gingivalis and/or F. nucleatum with a trend towards a Th2 response in P. gingivalis-immunized mice and a significantly increased anti-P. gingivalis IgG2a (Th1) response in mice immunized with F. nucleatum prior to P. gingivalis. Further, the inhibition of neutrophil phagocytosis of immune serum-opsonized P. gingivalis was modulated by the presence of anti-F. nucleatum antibodies, while anti-P. gingivalis antibodies induced an inhibitory effect on the phagocytic response to F. nucleatum.

Animals↗

PubMed2005

Synergy between Tannerella forsythia and Fusobacterium nucleatum in biofilm formation.

During dental plaque formation, the interaction of different organisms is important in the development of complex communities. Fusobacterium nucleatum is considered a 'bridge-organism' that facilitates colonization of other bacteria by coaggregation-mediated mechanisms and possibly by making the environment conducive for oxygen intolerant anaerobes. These studies were carried out to determine whether coaggregation between F. nucleatum and Tannerella forsythia is important in the formation of mixed species biofilms. Further, the role of BspA protein, a surface adhesin of T. forsythia, in coaggregation and biofilm formation was investigated. The results showed the development of synergistic mixed biofilms of F. nucleatum and T. forsythia when these bacteria were cocultured. The BspA protein was not involved in biofilm formation. Though BspA plays a role in coaggregation with F. nucleatum, presumably other adhesins are also involved. The synergistic biofilm formation between the two species was dependent on cell-cell contact and soluble components of the bacteria were not required. This study demonstrates that there is a positive synergy between F. nucleatum and T. forsythia in the development of mixed biofilms and that the cell-cell interaction is essential for this phenomenon.

Adhesins, Bacterial↗

PubMed2006

Response of human macrophage-like cells to stimulation by Fusobacterium nucleatum ssp. nucleatum lipopolysaccharide.

Monocytes/macrophages are key members of the innate immune system and are present in higher numbers in active periodontal lesions than in inactive sites. The aim of this study was to characterize the response of human monocyte U937 cells, differentiated into adherent macrophages by treatment with phorbol-12-myristate 13-acetate, to stimulation by Fusobacterium nucleatum ssp. nucleatum lipopolysaccharide. Attachment of (3)H-lipopolysaccharide to macrophage-like cells was partially inhibited by anti-CD14 and anti-TLR4 polyclonal antibodies. Fusobacterial lipopolysaccharide did not cause cell apoptosis or block apoptosis induced by camptothecin. Lipopolysaccharide up-regulated the secretion of the pro-inflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha as well as the chemokine interleukin-8 by macrophage-like cells. In addition, it increased phospholipase C and D activities, which likely contributed to the high levels of prostaglandin E(2) detected in the cell culture supernatant. Lastly, the amount of matrix metalloproteinase-9 produced by macrophage-like cells was significantly increased by the lipopolysaccharide treatment. Interestingly, fusobacterial cells acquired matrix metalloproteinase-9 activity following incubation in the presence of the culture supernatant of lipopolysaccharide-stimulated macrophage-like cells. In summary, the lipopolysaccharide of F. nucleatum ssp. nucleatum has a large array of biological effects on macrophage-like cells. This monocytic responsiveness to lipopolysaccharide may be a key regulator of periodontitis.

Apoptosis↗

PubMed1979

Immunochemical studies of partially hydrolyzed lipopolysaccharide from Fusobacterium nucleatum Fev1.

Fusobacterium nucleatum Fev1 lipopolysaccharide was split by hydrolysis with 1% acetic acid into acid-soluble polysaccharide and lipid A. Gel filtration of the polysaccharide on Bio-Gel P-60 gave a high-molecular-weight fraction eluted with the void volume, and a fraction eluted at 2.4 x Vo. The high-molecular-weight fraction contained L-glycero-D-manno-heptose in relatively large amounts, glucose, glucosamine, an unknown amino compound and small amounts of (or no) D-glycero-D-manno-heptose. Phosphorus and 3-deoxy-D-manno-octulosonic acid were not detected. The other fraction contained L- and D-glycero-D-manno-heptose, glucose, glucosamine, 3-deoxy-d-manno-octulosonic acid and phosphorus. Further fractionation experiments and serological investigations indicated that the high-molecular-weight fraction carried the O-antigenic side chains, whereas the material eluted from Bio-Gel P-60 at 2.4 x Vo represented the core oligosaccharide.

Antigens, Bacterial↗

PubMed1993

Structural studies of the O-antigenic polysaccharide of Fusobacterium necrophorum.

The O-specific polysaccharide component of the lipopolysaccharide produced by Fusobacterium necrophorum is of the teichoic acid type, with repeating units connected by phosphoric diester linkages. Dephosphorylation of the polysaccharide by treatment with aqueous hydrogen fluoride yielded a carbohydrate composed of a trisaccharide linked to an acidic component. This product, and the polysaccharide, were investigated by chemical methods and 1H-, 13C-, 31P- and 15N-NMR spectroscopy and the former also by fast-atom-bombardment mass spectrometry. It is proposed that the polysaccharide is composed of repeating units having the following structure, in which Fuc represents fucose (6-deoxy-galactose), Am represents an acetamidino group and Sug 2,4-diamino-2,4,6-trideoxy-D-glucose ('bacillosamine') acetylated at the 2-position and acylated with a (S)-3-hydroxybutanoic acid at the 4-position. The acid was identified as a 2-amino-2-deoxy-2-C-methyl-pentonic acid (2-amino-2-methyl-3,4,5-trihydroxypentanoic acid). The configuration of this acid remains to be determined. [formula: see text]

Abscess↗

PubMed1995

The Fusobacterium nucleatum major outer-membrane protein (FomA) forms trimeric, water-filled channels in lipid bilayer membranes.

The pore-forming activity of the major outer-membrane protein FomA of the anaerobic Fusobacterium nucleatum was studied in artificial lipid bilayer membranes. FomA was isolated from F. nucleatum strains Fev1, ATCC 10953, and ATCC 25586 by extraction with lithium dodecyl sulfate and lithium chloride and had an apparent molecular mass of about 40 kDa. When solubilized at low temperatures, the protein ran with an apparent molecular mass of about 62 kDa on SDS/PAGE. Cross-linking experiments and two-dimensional SDS/PAGE gave evidence that the 62-kDa protein band represented the trimeric form of FomA. The protein trimers were susceptible to SDS and temperature. The stability of the porin trimers varied among the strains. The properties of the FomA channels were studied in reconstitution experiments with black lipid bilayer membranes. The F. nucleatum porins formed channels with single-channel conductances in the range 0.66-1.30 nS in M KCl. The single-channel conductance was a function of the mobilities of the ions present in the aqueous solution bathing the bilayer membrane. This means that FomA forms general diffusion channels since (a) the conductance showed a linear dependence on the salt concentration, (b) the ion selectivity was small and varied for the three strains, and (c) the channels did not exhibit any binding site for maltotriose or triglycine. The water-filled channel was voltage dependent, and conductance decrements were observed at transmembrane potentials of +/- 50 mV. The conductance decrement steps were about one-third of the total conductance of a functional unit in its fully 'open' state. This strongly suggests that the trimer is the functional unit of the porin.

Bacterial Outer Membrane Proteins↗

PubMed1988

Shwartzman reaction in the brain induced by fractions of Fusobacterium necrophorum and Escherichia coli lipopolysaccharide in rabbits.

Multifocal fibrin thrombosis and suppurative meningitis in the central nervous system was induced by intracerebral inoculation with a cytoplasmic or supernatant fraction of Fusobacterium necrophorum followed by intravenous inoculation with Escherichia coli lipopolysaccharide endotoxin in rabbits. Formation of fibrin thrombosis was reduced by heparin administration. Single intracerebral inoculation with the cytoplasmic or supernatant fraction caused suppurative meningitis. Nervous lesions were often associated with fibrinoid degeneration of the blood vessels. Bacterial lipopolysaccharide endotoxin did not induce apparent meningitis or fibrin thrombosis. The formation of fibrin thrombosis in the central nervous system might be attributable to the Shwartzman reaction.

Animals↗

PubMed1995

Dermonecrotic activity of a cell wall preparation from Fusobacterium necrophorum.

A cell wall preparation of Fusobacterium necrophorum induced haemorrhagic necrosis in the skins of guinea pigs and rabbits. Effects in mice and rats were weak or absent. The toxic activity of the cell wall preparation was not reduced by heat treatment. A dermonecrotic toxin was isolated from the cell wall preparation with sodium dodecylsulphate and concentrated by precipitation with ethanol. A preparation of the bacterial cytoplasm from Fus. necrophorum induced mainly erythema.

Animals↗

PubMed1999

Fusobacterium necrophorum haemolysin stimulates motility of ileal longitudinal smooth muscle of the guinea-pig.

Fusobacterium necrophorum haemolysin (0.5-3.1 mg protein/mL) dose-dependently induced contractions of the isolated ileal longitudinal smooth muscle of the guinea-pig. The haemolysin (3.1 mg protein/mL) -induced maximum contraction of 75% of the response to 60 mM K+ declined within 17 min and the muscles then demonstrated rhythmic contractions. Tetrodotoxin (3.1 x 10(-6) M) had no effect on the contraction due to the haemolysin. After incubation in Ca(2+)-free medium, the ileal response to the haemolysin was lost. Verapamil, a Ca2+ channel blocker, dose-dependently inhibited the contraction to the haemolysin. The rabbit anti-serum against F. necrophorum haemolysin inhibited the haemolysin-induced contraction of ileal muscle. The bacterial haemagglutinin and the lipopolysaccharide had no effect on the response of ileal muscle. These findings suggest that the haemolysin-induced direct stimulation of ileal motility dependant on Ca2+ influx will increase the probability of contact of F. necrophorum and ileal mucosa and could increase the chances of colonization for F. necrophorum.

Animals↗

PubMed1990

Blastogenesis and polyclonal immunoglobulin synthesis in murine spleen cells stimulated with lipopolysaccharide, lipid A and acid-degraded polysaccharide from Fusobacterium nucleatum.

Lipopolysaccharide of Fusobacterium nucleatum strain Fevl was split by acid hydrolysis. The split products, i.e. lipid A and degraded polysaccharide were mitogenic for murine spleen cells as measured by uptake of [3H]thymidine. The uptake of [3H]thymidine was dose-dependent. Incubation of spleen cells with stimulants for 3 days resulted in a polyclonal activation of immunoglobulin synthesis. Higher mitogenic response and immunoglobulin production were found in spleen cells of athymic mice compared to those of thymic mice. The activity of lipid A in stimulating immunoglobulin synthesis was comparable with the parent lipopolysaccharide-Fevl, the degraded polysaccharide being the less potent stimulator.

Animals↗

PubMed1991

Synergistic effect on blastogenesis in murine spleen cells of lipopolysaccharide, lipid A, and acid-degraded polysaccharide from Fusobacterium nucleatum.

Interchangeable combinations of Fusobacterium nucleatum Fev1 lipopolysaccharide (LPS) with its split products by acetic acid hydrolysis, i.e. lipid A (LA) and degraded polysaccharide (PS), amplified the blastogenic response in murine spleen cell cultures as measured by [3H]thymidine uptake. Athymic murine spleen cells precultured with LPS-Fev1 for 48 h (stage 1), washed twice and cultured together with fresh cells and either LA or PS for 72 h (stage 2) gave a synergistic response over that found in spleen cell cultures of thymic mice. Spleen cells pre-cultured with LA or PS and with fresh cells and LPS-Fev1 added to stage 2 cultures gave less significant amplification compared with precultures of LPS and either LA or PS together with fresh cells added to stage 2. Precultures with LA, PS or LPS-Fev1 and with pokeweed mitogen (PWM) and fresh cells added produced an additional increment of synergy which was most pronounced in spleen cell cultures of normal mice.

Acetates↗

PubMed1993

Restriction fragment length polymorphism analysis of Fusobacterium necrophorum using a novel repeat DNA sequence and a 16S rRNA gene probe.

A repeated DNA sequence was isolated from Fusobacterium necrophorum biotype AB, strain FnS1. The repeated sequence shared considerable homology with the transposase gene from the Pseudomonas syringiae insertion sequence IS801. The repeat sequence was used together with a 16S ribosomal RNA gene probe to type F. necrophorum isolates using restriction fragment length polymorphisms. The probes revealed differences between several clinical isolates and will be useful tools to study the epidemiology of ovine foot abscess and other diseases caused by F. necrophorum.

Amino Acid Sequence↗

PubMed1994

Biochemical and biological characterization of ruminal Fusobacterium necrophorum.

Biochemical characteristics, biological activities, and antimicrobial susceptibilities of ruminal Fusobacterium necrophorum (eight subsp. necrophorum and eight subsp. funduliforme) and of isolates (three of each subsp.) obtained from bovine hepatic abscesses were determined. F. necrophorum subsp. necrophorum strains had higher phosphatase and DNase activities, produced more leukotoxin, and were more pathogenic to mice than subsp. funduliforme strains. The leukotoxin titer for culture supernatants of ruminal subsp. necrophorum strains was approximately 15 times lower than that of hepatic subsp. necrophorum strains. Hemagglutination activity was present in all hepatic, but only in some ruminal, strains of subsp. necrophorum. The antimicrobial sensitivity profile of the ruminal isolates was similar to that of hepatic isolates.

Animals↗

PubMed1994

Sizing the Fusobacterium nucleatum genome by pulsed-field gel electrophoresis.

The genome sizes of Fusobacterium nucleatum strains F1, F3, F6, ATCC 10953, ATCC 25586 and Fev1 were determined by pulsed-field gel electrophoresis (PFGE). The restriction enzymes SmaI, SacII,SalI and XhoI were found to generate a reasonable number of DNA fragments which could be separated by PFGE in agarose gels. The apparent chromosomal lengths of the F. nucleatum strains were determined to be approximately 2.4 million base pairs. This was within the size-range found by experiments exploiting renaturation kinetics.

Chromosome Mapping↗

PubMed1997

Interactions between Fusobacterium necrophorum hemolysin, erythrocytes and erythrocyte membranes.

The interactions between the hemolysin of Fusobacterium necrophorum subsp. necrophorum, erythrocytes and erythrocyte membranes were studied as an attempt to determine the initial characteristics leading to hemolysis. The spectrum of erythrocyte sensitivity indicated that horse, dog and mouse erythrocytes were highly sensitive whereas those of cattle, sheep, goat and chicken were insensitive to the hemolysin. Binding of hemolysin to horse and dog erythrocytes or their ghosts was more pronounced than to those of cattle and sheep as detected by a decrease of hemolytic activity from hemolysin preparations. The kinetics of hemolysis revealed that lysis is preceded by a prelytic phase characterized by binding of hemolysin to erythrocytes. Treatment of horse erythrocytes with hemolysin at various temperatures prior to incubation at 37 degrees C also revealed that this binding prelytic phase is temperature independent. This was followed by a temperature dependent lytic stage since erythrocytes pretreated with hemolysin and incubated at 4 degrees C showed no hemolysis. An inverse relation was found between erythrocyte concentration and hemolytic activity suggesting a multiple-hit mechanism of hemolysis.

Animals↗

PubMed1998

The erythrocyte receptor for Fusobacterium necrophorum hemolysin: phosphatidylcholine as a possible candidate.

An attempt was made to determine the receptor for the hemolysin of Fusobacterium necrophorum using horse erythrocyte or its membranes as target. The spectrum of erythrocyte sensitivity has indicated that horse, dog and mouse erythrocytes are highly sensitive whereas cattle, sheep, goat and chicken red blood cells are insensitive to this hemolysin. A high correlation between sensitivity and phosphatidylcholine content of the erythrocyte membranes was noted. Binding of hemolysin to horse erythrocyte membranes was reduced significantly by prior treatment of membranes with phospholipase A2 but not with phospholipase C. Pretreatment of erythrocyte membranes with pronase, proteinase K, trypsin or neuraminidase did not alter binding of hemolysin to the membranes, suggesting that protein or sialyl residues are not involved as receptors. Gas liquid chromatography analysis showed that the fatty acid profile from hydrolysis of bovine liver phosphatidylcholine by hemolysin and phospholipase A2 were similar. In conclusion, this report presents evidence that phosphatidylcholine may be acting as a possible receptor for the hemolysin of F. necrophorum.

Animals↗

PubMed2000

Peptostreptococcus micros coaggregates with Fusobacterium nucleatum and non-encapsulated Porphyromonas gingivalis.

Coaggregation is one of the potential colonization strategies of oral microorganisms, often involving fimbrial structures in the interactions. In this study, the coaggregation characteristics of the rough and smooth genotypes of the periodontal pathogen Peptostreptococcus micros were compared to investigate the role of the fibril-like structures of the rough genotype in coaggregation. Of the 11 oral species tested, only Fusobacterium nucleatum strains and non-encapsulated Porphyromonas gingivalis strains coaggregated with P. micros. No differences in coaggregation between the smooth type (Sm), the rough type (Rg) and the smooth variant of the Rg type (Rg(Sm)) of P. micros were observed. Heat-stable, periodate-sensitive structures on P. micros appeared to interact with heat- and protease-sensitive structures on F. nucleatum and P. gingivalis. These data indicate that these unimodal coaggregations are not mediated by the proteinaceous fibril-like structures of the Rg genotype, but by carbohydrates present on both genotypes of P. micros.

Amino Acids↗

PubMed2000

The response to oxidative stress of Fusobacterium nucleatum grown in continuous culture.

Fusobacterium nucleatum ATCC 10953 was grown in continuous culture and the atmosphere changed stepwise from nitrogen (anaerobiosis) to a mixture of air: oxygen (40:60). No significant differences in biomass were observed and the baseline low level of superoxide dismutase increased only slightly; catalase and peroxidase activities were never detected but the level of NADH oxidase increased more than three-fold when oxygen was introduced into the system. In relation to acidic end-products, the relative proportion of acetate increased while that of butyrate decreased. Due mainly, it would seem, to NADH oxidase activity, the culture maintained a low redox potential (E(h)=-274 mV) even under an atmosphere of 40% oxygen in air and dissolved oxygen was not detected. This may, in part, explain the protective role of F. nucleatum for anaerobes in both biofilm and planktonic phases of aerated, mixed cultures of oral bacteria.

Acetates↗