bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of Fungal Cell Wall Components in Adhesion ofSporothrix schenckiito Human Fibronectin
Authors: Lima Osana C. , Figueiredo Camila C. , Previato José O. , Mendonça-Previato Lucia , Morandi Verônica , Lopes Bezerra Leila M. 
Published: July 2002

ABSTRACTSystemic sporotrichosis is an emerging infection potentially fatal for immunocompromised patients. Adhesion to extracellular matrix proteins is thought to play a crucial role in invasive fungal diseases. Here we report studies of the adhesion ofSporothrix schenckiito the extracellular protein fibronectin (Fn). Both yeast cells and conidia ofS. schenckiiwere able to adhere to Fn as detected by enzyme-linked immunosorbent binding assays. Adhesion of yeast cells to Fn is dose dependent and saturable.S. schenckiiadheres equally well to 40-kDa and 120-kDa Fn proteolytic fragments. While adhesion to Fn was increased by Ca2+, inhibition assays demonstrated that it was not RGD dependent. A carbohydrate-containing cell wall neutral fraction blocked up to 30% of the observed adherence for the yeast cells. The biochemical nature of this fraction suggests the participation of cell surface glycoconjugates in binding by their carbohydrate or peptide moieties. These results provide new data concerningS. schenckiiadhesion mechanisms, which could be important in host-fungus interactions and the establishment of sporotrichosis.
Identification of Independent
Streptococcus gordonii
SspA and SspB Functions in Coaggregation with
Actinomyces naeslundii
Authors: Egland Paul G. , Dû Laurence D. , Kolenbrander Paul E. 
Published: July 2002

ABSTRACT

The initial stages of dental plaque formation involve the adherence of early colonizing organisms such as
Streptococcus gordonii
and
Actinomyces naeslundii
to the saliva-coated tooth surface and to each other. The
S. gordonii
surface proteins SspA and SspB are known to play a role in adherence to salivary proteins and mediate coaggregation with other bacteria. Coaggregation is the adhesin receptor-mediated interaction between genetically distinct cell types and appears to be ubiquitous among oral isolates. To define the function of SspA and SspB separately on the surface of their natural host, we constructed and analyzed the coaggregation properties of an isogenic
sspB
mutant of
S. gordonii
DL1, an
sspAB
double mutant, and a previously described
sspA
mutant.
A. naeslundii
strains have been previously classified into six coaggregation groups based on the nature of their coaggregations with
S. gordonii
DL1 and other oral streptococci. Coaggregation assays with the
sspA
and
sspB
mutants showed that SspA and SspB are the streptococcal proteins primarily responsible for defining these coaggregation groups and, thus, are highly significant in the establishment of early dental plaque. SspA exhibited two coaggregation-specific functions. It participated in lactose-inhibitable and -noninhibitable interactions, while SspB mediated only lactose-noninhibitable coaggregations. Accordingly, the
sspAB
double mutant lacked these functions and allowed us to detect a third coaggregation interaction with one of these organisms. These proteins may play an important role in development of
S. gordonii-A. naeslundii
communities in early dental plaque. Understanding these adhesin proteins will aid investigations of complex microbial communities that characterize periodontal diseases.
Antibodies against Listerial Protein 60 Act as an Opsonin for Phagocytosis ofListeria monocytogenesby Human Dendritic Cells
Authors: Kolb-Mäurer Annette , Pilgrim Sabine , Kämpgen Eckhart , McLellan Alexander D. , Bröcker Eva-Bettina , Goebel Werner , Gentschev Ivaylo 
Published: July 2002

ABSTRACTHuman-monocyte-derived dendritic cells (MoDC) are very efficient in the uptake ofListeria monocytogenes, a gram-positive bacterium which is an important pathogen in humans and animals causing systemic infections with symptoms such as septicemia and meningitis. In this work, we analyzed the influence of blood plasma on the internalization ofL. monocytogenesinto human MoDC and compared the uptake ofL. monocytogeneswith that ofSalmonella entericaserovar Typhimurium andYersinia enterocolitica. While human plasma did not significantly influence the uptake of serovar Typhimurium andY. enterocoliticaby human MoDC, the efficiency of the uptake ofL. monocytogenesby these phagocytes was strongly enhanced by human plasma. In plasma-free medium the internalization ofL. monocytogeneswas very low, whereas the addition of pooled human immunoglobulins resulted in the internalization of these bacteria to a degree comparable to the highly efficient uptake observed with human plasma. All human plasma tested contained antibodies against the 60-kDa extracellular protein ofL. monocytogenes(p60), and anti-p60 antibodies were also found in the commercially available pooled immunoglobulins. Strikingly, in contrast toL. monocytogeneswild type, aniapdeletion mutant (totally deficient in p60) showed only a minor difference in the uptake by human MoDC in the presence or the absence of human plasma. These results support the assumption that antibodies against the listerial p60 protein may play an important role in Fc-receptor-mediated uptake ofL. monocytogenesby human MoDC via opsonization of the bacteria. This process may have a major impact in preventing systemic infection inL. monocytogenesin immunocompetent humans.
Characterization of the
groESL
Operon in
Listeria monocytogenes
: Utilization of Two Reporter Systems (
gfp
and
hly
) for Evaluating In Vivo Expression
Authors: Gahan Cormac G. M. , O'Mahony James , Hill Colin 
Published: July 2002

ABSTRACT

The ability of intracellular pathogens to sense and adapt to the hostile environment of the host is an important factor governing virulence. We have sequenced the operon encoding the major heat shock proteins GroES and GroEL in the gram-positive food-borne pathogen
Listeria monocytogenes
. The operon has a conserved orientation in the order
groES groEL
. Upstream of
groES
and in the opposite orientation is a gene encoding a homologue of the
Bacillus subtilis
protein YdiL, while downstream of
groEL
is a gene encoding a putative bile hydrolase. We used both reverse transcriptase-PCR (RT-PCR) and transcriptional fusions to the UV-optimized
Aequorea victoria
green fluorescent protein (GFP
UV
) to analyze expression of
groESL
under various environmental stress conditions, including heat shock, ethanol stress, and acid shock, and during infection of J774 mouse macrophage cells. Strains harboring GFP
UV
transcriptional fusions to the promoter region of
groESL
demonstrated a significant increase in fluorescence following heat shock that was detected by both fluorimetry and fluorescence microscopy. Using both RT-PCR and GFP technology we detected expression of
groESL
following internalization by J774 cells. Increased intracellular expression of
dnaK
was also determined using RT-PCR. We have recently described a system which utilizes
L. monocytogenes
hemolysin as an in vivo reporter of gene expression within the host cell phagosome (C. G. M. Gahan and C. Hill, Mol. Microbiol. 36:498–507, 2000). In this study a strain was constructed in which hemolysin expression was placed under the control of the
groESL
promoter. In this strain hemolysin expression during infection also confirms transcription from the
groESL
promoter during J774 and murine infection, albeit at lower levels than the known virulence factor
plcA
.
Porphyromonas gingivalisGingipain-R Enhances Interleukin-8 but Decreases Gamma Interferon-Inducible Protein 10 Production by Human Gingival Fibroblasts in Response to T-Cell Contact
Authors: Oido-Mori Mari , Rezzonico Roger , Wang Pao-Li , Kowashi Yusuke , Dayer Jean-Michel , Baehni Pierre C. , Chizzolini Carlo 
Published: July 2002

ABSTRACTProteases produced byPorphyromonas gingivalis, an oral pathogen, are considered important virulence factors and may affect the responses of cells equipped with proteinase-activated receptors. The aim of this study was to investigate the effect of the arginine-specific cysteine protease gingipain-R produced byP. gingivalison chemokine production by human gingival fibroblasts (HGF) and the effect of gingipain-R treatment on the subsequent contact-dependent activation of HGF by T cells. HGF incubated in the presence of purified 47-kDa gingipain-R showed increased levels of interleukin-8 (IL-8) mRNA. Cyclooxygenase-2 (COX-2) mRNA was also induced. Further exposure of HGF to activated T cells resulted in the dose- and time-dependent enhancement of IL-8 transcription and release. T-cell membrane-bound tumor necrosis factor (TNF) was the ligand inducing IL-8 production by HGF, since TNF neutralization abrogated HGF responses to T-cell contact. The enhanced IL-8 release was due, at least in part, to prostaglandin-E2production, which was mostly blocked by indomethacin. Gingipain-R proteolytic activity was required since heat inactivation, specific synthetic protease inhibitors, and the natural substrate competitor histatin 5 abrogated its effects. The enhanced production of IL-8 in response to T-cell contact was specific since monocyte chemotactic protein-1 (MCP-1) production was unaffected while interferon-gamma-inducible protein-10 (IP-10) was inhibited. The sum of these activities may result in the recruitment of differential cell types to sites of inflammation since IL-8 preferentially recruits neutrophils and IP-10 attracts activated T cells and may be relevant to the pathogenesis of periodontitis.
Characterization and Protective Potential of the Immune Response toTaenia soliumParamyosin in a Murine Model of Cysticercosis
Authors: Vázquez-Talavera José , Solı́s Carlos F. , Terrazas Luis I. , Laclette Juan P. 
Published: July 2002

ABSTRACTParamyosin has been proposed as a vaccine candidate in schistosomiasis and filariasis. However, limited information is available about its protective potential against cysticercosis and the immune response it induces. Immunization of mice with recombinant full-length paramyosin ofTaenia solium(TPmy) results in about a 52% reduction in parasite burden after a subsequent challenge by intraperitoneal inoculation ofTaenia crassicepscysticerci. Immunization assays using recombinant fragments of TPmy, corresponding approximately to thirds on the amino, central, or carboxyl regions, suggest that protective epitopes are located mostly in the amino-end third. Proliferation assays using T cells obtained from mice immunized with the full-length recombinant TPmy also showed a preferential response to the amino-terminal fragment. In contrast, antibodies in the sera from these mice predominantly recognize epitopes located in the carboxyl-terminal fragment, being the immunoglobulin G1 subclass, the predominant antibody isotype. Characterization of the cellular immune response induced against the protective amino-terminal fragment reveals production of gamma interferon and interleukin-2, but not interleukin-4, suggesting a Th1-like profile.
Type 3 Fimbrial Shaft (MrkA) of
Klebsiella pneumoniae
, but Not the Fimbrial Adhesin (MrkD), Facilitates Biofilm Formation
Authors: Langstraat Jennifer , Bohse Megan , Clegg Steven 
Published: July 2002

ABSTRACT

Isolates of
Klebsiella pneumoniae
are responsible for opportunistic infections, particularly of the urinary tract and respiratory tract, in humans. These bacteria express type 3 fimbriae that have been implicated in binding to eucaryotic cells and matrix proteins. The type 3 fimbriae mediate binding to target tissue using the MrkD adhesin that is associated with the fimbrial shaft comprised of the MrkA protein. The formation of biofilms in vitro by strains of
K. pneumoniae
was shown to be affected by the production of fimbriae on the bacterial surface. However, a functional MrkD adhesin was not necessary for efficient biofilm formation. Nonfimbriate strains were impaired in their ability to form biofilms. Using isogenic fimbriate and nonfimbriate strains of
K. pneumoniae
expressing green fluorescent protein it was possible to demonstrate that the presence of type 3 fimbriae facilitated the formation of dense biofilms in a continuous-flowthrough chamber. Transformation of nonfimbriate mutants with a plasmid possessing an intact
mrk
gene cluster restored the fimbrial phenotype and the rapid ability to form biofilms.
Dietary Glycine Prevents Peptidoglycan Polysaccharide-Induced Reactive Arthritis in the Rat: Role for Glycine-Gated Chloride Channel
Authors: Li Xiangli , Bradford Blair U. , Wheeler Michael D. , Stimpson Stephen A. , Pink Heather M. , Brodie Thomas A. , Schwab John H. , Thurman Ronald G. 
Published: July 2002

ABSTRACTPeptidoglycan polysaccharide (PG-PS) is a primary structural component of bacterial cell walls and causes rheumatoid-like arthritis in rats. Recently, glycine has been shown to be a potential immunomodulator; therefore, the purpose of this study was to determine if glycine would be protective in a PG-PS model of arthritis in vivo. In rats injected with PG-PS intra-articularly, ankle swelling increased 21% in 24 to 48 h and recovered in about 2 weeks. Three days prior to reactivation with PG-PS given intravenously (i.v.), rats were divided into two groups and fed a glycine-containing or nitrogen-balanced control diet. After i.v. PG-PS treatment joint swelling increased 2.1 ± 0.3 mm in controls but only 1.0 ± 0.2 mm in rats fed glycine. Infiltration of inflammatory cells, edema, and synovial hyperplasia in the joint were significantly attenuated by dietary glycine. Tumor necrosis factor alpha (TNF-α) mRNA was detected in ankle homogenates from rats fed the control diet but not in ankles from rats fed glycine. Moreover, intracellular calcium was increased significantly in splenic macrophages treated with PG-PS; however, glycine blunted the increase about 50%. The inhibitory effect of glycine was reversed by low concentrations of strychnine or chloride-free buffer, and it increased radiolabeled chloride influx nearly fourfold, an effect also inhibited by strychnine. In isolated splenic macrophages, glycine blunted translocation of the p65 subunit of NF-κB into the nucleus, superoxide generation, and TNF-α production caused by PG-PS. Further, mRNA for the beta subunit of the glycine receptor was detected in splenic macrophages. This work supports the hypothesis that glycine prevents reactive arthritis by blunting cytokine release from macrophages by increasing chloride influx via a glycine-gated chloride channel.
Muramic Acid Is Not Generally Present in the Human Spleen as Determined by Gas Chromatography-Tandem Mass Spectrometry
Authors: Kozar Michael P. , Laman Jon D. , Fox Alvin 
Published: July 2002

ABSTRACTIt has been hypothesized that bacterial debris may accumulate in tissues of the reticuloendothelial system (RES) serving as an inflammatory stimulus for human disease. In support of this hypothesis, muramic acid (Mur), a component of bacterial peptidoglycan (PG), has previously been reported to be present in culture-negative human spleen. High-performance liquid chromatography (HPLC) was employed in these analyses, and a peak was detected at the retention time of Mur. However, HPLC is best used as a screening technique, and it is vital that these tentative observations be reexamined by the state-of-the-art approach (gas chromatography-tandem mass spectrometry [GC-MS2]). Indeed, in the present work using GC-MS2, Mur was not detected in six out of seven human spleens previously examined by HPLC. However, Mur was categorically detected at minute concentrations, 50 ppb, in one spleen. In conclusion, since Mur is not generally found in culture-negative human spleen, in future studies, these tissues can serve as negative controls. The study of Mur levels in inflammation (e.g., reactive arthritis) could prove important in testing the hypothesis that bacterial debris persisting in tissues could serve as a depot inciting diseases of unknown etiology.
Endogenous Pro- and Anti-Inflammatory Cytokines Differentially Regulate an In Vivo Humoral Response toStreptococcus pneumoniae
Authors: Khan Abdul Q. , Shen Yi , Wu Zheng-Qi , Wynn Thomas A. , Snapper Clifford M. 
Published: July 2002

ABSTRACTProinflammatory cytokines play a critical role in innate host defense against extracellular bacteria. However, little is known regarding the effects of these cytokines on the adaptive humoral response. Mice injected with a neutralizing anti-tumor necrosis factor alpha (TNF-α) monoclonal antibody (MAb) at the time of primary immunization with intactStreptococcus pneumoniae(strain R36A) showed a substantial reduction in both the primary immunoglobulin G (IgG) response specific for the cell wall protein, pneumococcal surface protein A (PspA), as well as in the development of PspA-specific memory. In contrast, anti-TNF-α MAb injected only at the time of secondary immunization with R36A failed to alter the boosted anti-PspA response. TNF-α was required only within the first 48 to 72 h after primary immunization with R36A and was induced both by non-B and non-T cells and by lymphoid cells, within 2 to 6 h after immunization, with levels returning to normal by 24 h. Thus, the early innate release of TNF-α was critical for optimal stimulation of the subsequent adaptive humoral response to R36A. Additional proinflammatory (interleukin 1 [IL-1], IL-6, IL-12, and gamma interferon [IFN-γ]) as well as anti-inflammatory (IL-4 and IL-10) cytokines were also transiently induced. Mice genetically deficient in IL-6, IFN-γ, or IL-12 also showed a reduced IgG anti-PspA response of all IgG isotypes. In contrast, IL-4−/−and IL-10−/−mice immunized with R36A showed a significant elevation in the IgG anti-PspA response, except that there was decreased IgG1 in IL-4−/−mice. In this regard, a marked enhancement in the induction of proinflammatory cytokines was observed in the absence of IL-10, relative to controls. Ig isotype titers specific for the phosphorycholine determinant of C-polysaccharide were similarly regulated, but to a much more modest degree. These data suggest that proinflammatory and anti-inflammatory cytokines differentially regulate an in vivo protein- and polysaccharide-specific Ig response to an extracellular bacteria.
Type III Group B Streptococcal Polysaccharide Induces Antibodies That Cross-React withStreptococcus pneumoniaeType 14
Authors: Guttormsen Hilde-Kari , Baker Carol J. , Nahm Moon H. , Paoletti Lawrence C. , Zughaier Susu M. , Edwards Morven S. , Kasper Dennis L. 
Published: July 2002

ABSTRACTCovalent linkage of a bacterial polysaccharide to a protein greatly enhances the carbohydrate's immunogenicity and its binding to solid surfaces in immunoassays. These findings have spurred the development of glycoconjugate vaccines to prevent serious bacterial infections as well as the use of glycoconjugates as coating antigens in bioassays. We evaluated sera from women immunized with unconjugated group B streptococcal (GBS) type III (GBS III) polysaccharide (IIIPS) or with IIIPS covalently linked to tetanus toxoid to assess specificity, sensitivity, and parallelism in dilution curves in two GBS III enzyme-linked immunosorbent assays (ELISAs). One assay used IIIPS mixed with methylated human serum albumin (IIIPS + mHSA) as the coating antigen, and the other used IIIPS covalently linked to HSA (III-HSA). Each coating antigen was associated with a highly specific GBS III bioassay. The sensitivity was higher in the III-HSA ELISA, in which conjugated IIIPS is bound to the plates. Parallelism in titration curves was observed in the III-HSA but not in the IIIPS + mHSA ELISA. The excellent correlation between the concentrations of GBS IIIPS-specific immunoglobulin G (IgG) and the opsonophagocytic activity of these antibodies indicated that the III-HSA assay can predict functionality of vaccine-induced IgG against GBS III disease. The structure of the repeating unit of the capsular polysaccharide of GBS III differs from that ofStreptococcus pneumoniaetype 14 (Pn14 PS) only by the presence on GBS III of a sialic acid residue at the end of the side chain. The majority of healthy adults responding to GBS III vaccines with a fourfold or greater increase in GBS III-specific IgG antibodies developed antibodies cross-reacting with Pn14 PS (i.e., desialylated GBS IIIPS). The proportion of GBS vaccine responders who developed IgG to the desialylated IIIPS did not depend on whether IIIPS was given in the unconjugated or conjugated form. When present, these vaccine-induced cross-reacting antibodies conferred in vitro antibody-mediated opsonophagocytosis and killing of both GBS III and Pn14, two pathogens that cause invasive disease in young infants.
Mucosal Tolerance to a Bacterial Superantigen Indicates a Novel Pathway To Prevent Toxic Shock
Authors: Collins L. Vincent , Eriksson Kristina , Ulrich Robert G. , Tarkowski Andrej 
Published: July 2002

ABSTRACTEnterotoxins with superantigenic properties secreted during systemicStaphylococcus aureusinfection are responsible for toxic shock. We show that intranasal administration of staphylococcal enterotoxin A (SEA), but not a recombinant SEA lacking superantigenic activity, protected mice against lethal systemic SEA challenge. Protection was superantigen specific since intranasal exposure to SEA would not protect against death caused by subsequent toxic shock syndrome toxin 1 systemic challenge. Protection was neither due to selective depletion of SEA-specific T-cell receptor Vβ families nor due to production of neutralizing anti-SEA antibodies. Importantly, the production of interleukin 10 (IL-10) induced by “tolerization” (that is, by the induction of immunological tolerance) contributed to the observed protection against lethal superantigen-triggered disease. In support of this notion we found that (i) significantly increased levels of IL-10 in sera of “tolerized” animals (that is, animals rendered tolerant) and (ii) IL-10−/−mice could not be tolerized by mucosal SEA administration. Altogether, this is the first study to show that mucosal tolerance to a superantigen is readily triggered by means of immunodeviation.
Vaccination of Pregnant Dams with Intimin
O157
Protects Suckling Piglets from
Escherichia coli
O157:H7 Infection
Authors: Dean-Nystrom Evelyn A. , Gansheroff Lisa J. , Mills Melody , Moon Harley W. , O'Brien Alison D. 
Published: July 2002

ABSTRACT

Cattle are important reservoirs of enterohemorrhagic
Escherichia coli
(EHEC) O157:H7 that cause disease in humans. Both dairy and beef cattle are asymptomatically and sporadically infected with EHEC. Our long-term goal is to develop an effective vaccine to prevent cattle from becoming infected and transmitting EHEC O157:H7 to humans. We used passive immunization of neonatal piglets (as a surrogate model) to determine if antibodies against EHEC O157 adhesin (intimin
O157
) inhibit EHEC colonization. Pregnant swine (dams) with serum anti-intimin titers of ≤100 were vaccinated twice with purified intimin
O157
or sham-vaccinated with sterile buffer. Intimin
O157
-specific antibody titers in colostrum and serum of dams were increased after parenteral vaccination with intimin
O157
. Neonatal piglets were allowed to suckle vaccinated or sham-vaccinated dams for up to 8 h before they were inoculated with 10
6
CFU of a Shiga toxin-negative (for humane reasons) strain of EHEC O157:H7. Piglets were necropsied at 2 to 10 days after inoculation, and intestinal samples were collected for determination of bacteriological counts and histopathological analysis. Piglets that ingested colostrum containing intimin
O157
-specific antibodies from vaccinated dams, but not those nursing sham-vaccinated dams, were protected from EHEC O157:H7 colonization and intestinal damage. These results establish intimin
O157
as a viable candidate for an EHEC O157:H7 antitransmission vaccine.