bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interleukin-18 and Gamma Interferon Production by Oral Epithelial Cells in Response to Exposure toCandida albicansor Lipopolysaccharide Stimulation
Authors: Rouabhia Mahmoud , Ross Geneviève , Pagé Nathalie , Chakir Jamila 
Published: November 2002

ABSTRACTOral candidiasis is a collective name for a group of disorders caused by the dimorphic fungusCandida albicans. Host defenses againstC. albicansessentially fall into two categories: specific immune mechanisms and local oral mucosal epithelial cell defenses. Since oral epithelial cells secrete a variety of cytokines and chemokines in response to oral microorganisms and sinceC. albicansis closely associated with oral epithelial cells as a commensal organism, we wanted to determine whether interleukin-18 (IL-18) and gamma interferon (IFN-γ) were produced by oral epithelial cells in response toC. albicansinfection and lipopolysaccharide (LPS) stimulation. Our results showed that IL-18 mRNA and protein were constitutively expressed by oral epithelial cells and were down-regulated byCandidainfections but increased following LPS stimulation. BothC. albicansand LPS significantly decreased pro-IL-18 (24 kDa) levels and increased active IL-18 (18 kDa) levels. This effect was IL-1β-converting-enzyme dependent. The increase in active IL-18 protein levels promoted the production of IFN-γ by infected cells. No effect was obtained with LPS. Although produced only at an early stage, secreted IFN-γ seemed to be a preferential response by oral epithelial cells toC. albicansgrowth. These results provide additional evidence for the contribution of oral epithelial cells to local (direct contact) and systemic (IL-18 and IFN-γ production) defense against exogenous stimulation such asC. albicansinfection or LPS stimulation.
Vaginal and Oral Epithelial Cell Anti-CandidaActivity
Authors: Nomanbhoy Fatema , Steele Chad , Yano Junko , Fidel, Paul L. 
Published: November 2002

ABSTRACTCandida albicansis the causative agent of acute and recurrent vulvovaginal candidiasis (VVC), a common mucosal infection affecting significant numbers of women in their reproductive years. While any murine host protective role for cell-mediated immunity (CMI), humoral immunity, and innate resistance by neutrophils against the vaginal infection appear negligible, significant in vitro growth inhibition ofCandidaspecies by vaginal and oral epithelial cell-enriched cells has been observed. Both oral and vaginal epithelial cell anti-Candidaactivity has a strict requirement for cell contact toC. albicanswith no role for soluble factors, and oral epithelial cells inhibitC. albicansthrough a cell surface carbohydrate moiety. The present study further evaluated the inhibitory mechanisms by murine vaginal epithelial cells and the fate ofC. albicansby oral and vaginal epithelial cells. Similar to human oral cells, anti-Candidaactivity produced by murine vaginal epithelial cells is unaffected by enzymatic cleavage of cell surface proteins and lipids but sensitive to periodic acid cleavage of surface carbohydrates. Analysis of specific membrane carbohydrate moieties, however, showed no role for sulfated polysaccharides, sialic acid residues, or glucose and mannose-containing carbohydrates, also similar to oral cells. Staining for live and deadCandidain the coculture with fluorescein diacetate (FDA) and propidium iodide (PI), respectively, showed a clear predominance of live organisms, suggesting a static rather than cidal action. Together, the results suggest that oral and vaginal epithelial cells retard or arrest the growth rather than killC. albicansthrough an as-yet-unidentified carbohydrate moiety in a noninflammatory manner.
Effect ofToxoplasma gondiiInfection Kinetics on Trophoblast Cell Population inCalomys callosus, a Model of Congenital Toxoplasmosis
Authors: Ferro E. A. V. , Silva D. A. O. , Bevilacqua E. , Mineo J. R. 
Published: November 2002

ABSTRACTThis work evaluated the kinetics of events that occur in the placenta ofCalomys callosusafterToxoplasma gondiiinfection. Animals on the first day of pregnancy (dop) and virgin nonpregnant females were perorally infected with 20 cysts ofT. gondiistrain ME49. After 100 days of infection, the virgin animals were mated and received an additional 20 cysts on the first dop. The placentas and the embryos from both acutely and chronically infected animals were analyzed up to day 20 of pregnancy by morphological and immunocytochemical assays. Noninfected and infected animals exhibited placenta with normal morphology. From the seventh dop and infection onwards, liver and spleen cells of the infected animals contained several parasitophorous vacuoles. On the 13th day, the maternal blood present at the placental blood spaces containedT. gondii-infected leukocytes. Infected placental cells were only seen on the 15th dop, being the trophoblast giant cells, the first cell type to contain signs of the parasite internalization, followed by labyrinth zone cells 24 h later and spongiotrophoblast cells only after the 19th dop. Fetal liver and brain were infected byT. gondiiconcomitantly to the labyrinth cell infection. No signals of infection were observed on placentas and embryos from chronically infected animals. Therefore, considering the sequence of events leading to the infection of the various organs, it could be hypothesized that the placenta is infected later on during pregnancy, which may be related to the defense roles played by this structure. However, trophoblast giant cells are unable to completely stop the progression ofT. gondiiinfection towards the fetal tissues.C. callosuswas demonstrated to be a suitable experimental model to study the dynamics of congenital toxoplasmosis.
Characterization of Two Novel Pyrogenic Toxin Superantigens Made by an Acute Rheumatic Fever Clone ofStreptococcus pyogenesAssociated with Multiple Disease Outbreaks
Authors: Smoot Laura M. , McCormick John K. , Smoot James C. , Hoe Nancy P. , Strickland Ian , Cole Robert L. , Barbian Kent D. , Earhart Cathleen A. , Ohlendorf Douglas H. , Veasy L. George , Hill Harry R. , Leung Donald Y. M. , Schlievert Patrick M. , Musser James M. 
Published: November 2002

ABSTRACTThe pathogenesis of acute rheumatic fever (ARF) is poorly understood. We identified two contiguous bacteriophage genes, designatedspeLandspeM, encoding novel inferred superantigens in the genome sequence of an ARF strain of serotype M18 group A streptococcus (GAS).speLandspeMwere located at the same genomic site in 33 serotype M18 isolates, and no nucleotide sequence diversity was observed in the 33 strains analyzed. Furthermore, the genes were absent in 13 non-M18 strains tested. These data indicate a recent acquisition event by a distinct clone of serotype M18 GAS.speLandspeMwere transcribed in vitro and upregulated in the exponential phase of growth. Purified SpeL and SpeM were pyrogenic and mitogenic for rabbit splenocytes and human peripheral blood mononuclear cells in picogram amounts. SpeL preferentially expanded human T cells expressing T-cell receptors Vβ1, Vβ5.1, and Vβ23, and SpeM had specificity for Vβ1 and Vβ23 subsets, indicating that both proteins had superantigen activity. SpeL was lethal in two animal models of streptococcal toxic shock, and SpeM was lethal in one model. Serologic studies indicated that ARF patients were exposed to serotype M18 GAS, SpeL, and SpeM. The data demonstrate that SpeL and SpeM are pyrogenic toxin superantigens and suggest that they may participate in the host-pathogen interactions in some ARF patients.
Functional Comparison of Serine Protease Autotransporters of
Enterobacteriaceae
Authors: Dutta Pinaki R. , Cappello Renato , Navarro-García Fernando , Nataro James P. 
Published: November 2002

ABSTRACT

The plasmid-encoded toxin (Pet) of enteroaggregative
Escherichia coli
(EAEC) belongs to a family of high-molecular-weight serine protease autotransporters of
Enterobacteriaceae
(SPATEs) which also includes Pic from EAEC and
Shigella flexneri
, EspC from enteropathogenic
E. coli
, EspP from enterohemorrhagic
E. coli
, Sat from uropathogenic
E. coli
, Tsh from avian pathogenic
E. coli
, and SepA from
S. flexneri
. Phylogenetic analysis shows the SPATE proteins to represent a distinct subfamily of autotransporters with amino acid identities ranging from 35 to 55%, providing a powerful resource to direct structure-function studies. In this study, we show that these related proteins are proteases with divergent substrate specificities, suggesting different functions. The cleavage profile of oligopeptides was found to be unique for each SPATE protein. The SPATEs showed proteolytic activity for several substrates, namely mucin, pepsin, human coagulation factor V, and erythroid spectrin. The cleavage of spectrin has been hypothesized as the mechanism through which Pet induces cytopathic effects. However, whereas Pet, Sat, and EspC cleaved spectrin, only Pet and Sat elicited cytopathic effects; the remaining SPATEs did not cause any morphological changes to HEp-2 cell monolayers. EspC and Pet exhibited acid-dissociable binding to HEp-2 cells. However, Pet was more efficient at entering HEp-2 cells, suggesting a basis for the different abilities of these two proteases to damage cells. Our data suggest that, despite the homologies observed among these proteins, the SPATEs have different pathogenetic functions only partly dependent on their substrate specificities.
Concomitant Cytosolic Delivery of Two Immunodominant Listerial Antigens bySalmonella entericaSerovar Typhimurium Confers Superior Protection against Murine Listeriosis
Authors: Igwe Emeka I. , Geginat Gernot , Rüssmann Holger 
Published: November 2002

ABSTRACTDuring its interaction with host cells,Salmonella entericaserovar Typhimurium employs a type III secretion system for cytosolic targeting of virulence factors. This protein translocation mechanism is a useful tool for heterologous antigen delivery by attenuatedSalmonellavaccine carrier strains. In the present study, we used theYersiniaouter protein E (YopE) as a carrier molecule forSalmonellatype III-dependent cytosolic delivery of the immunodominant CD8 T-cell antigens listeriolysin O (LLO) and p60 ofListeria monocytogenes. It is shown that concomitant translocation of hybrid YopE/LLO and YopE/p60 proteins bySalmonellaled to antigen presentation and CD8 T-cell priming efficacies comparable to those of translocation of single listerial antigens. However, simultaneous translocation of LLO and p60 significantly surpassed single cytosolic antigen delivery in the ability to protect againstListeria. For the first time, this study demonstrates that concomitant expression of two independent antigens via the same recombinant plasmid leads to superior protection against a challenge with an intracellular bacterial pathogen. In conclusion, these findings emphasize the versatility ofSalmonellatype III-mediated heterologous antigen delivery for the induction of cytotoxic T-lymphocyte-mediated immunity.
Construction of anActinobacillus pleuropneumoniaeSerotype 2 Prototype Live Negative-Marker Vaccine
Authors: Tonpitak Walaiporn , Baltes Nina , Hennig-Pauka Isabel , Gerlach Gerald F. 
Published: November 2002

ABSTRACTDeletions were introduced into theureCandapxIIAgenes of anActinobacillus pleuropneumoniaeserotype 2 strain by homologous recombination and counterselection. The double-mutant contains no foreign DNA, is highly attenuated, protects pigs from homologous challenge upon a single aerosol application, and facilitates the serological discrimination of immunized and infected herds.
Genetic Requirements for
Salmonella
-Induced Cytopathology in Human Monocyte-Derived Macrophages
Authors: Browne Sara H. , Lesnick Marc L. , Guiney Donald G. 
Published: November 2002

ABSTRACT

Infection of human macrophages with
Salmonella enterica
serovar Typhimurium or
Salmonella enterica
serovar Dublin produces delayed cytotoxicity characterized by cell detachment and associated apoptosis. Using a site-specific mutant in the SpvB active site, we verify that the ADP-ribosylation activity of SpvB is required for delayed cytotoxicity in human macrophages infected with
Salmonella
. SipB and the type III protein secretion system (TTSS) encoded by
Salmonella
pathogenicity island 1 (SPI1) are not involved, whereas the SPI2 TTSS is absolutely required for SpvB-dependent cytotoxicity. Furthermore, we show that infection of macrophage cultures with wild-type or
sipB
mutant bacteria led to a complete loss of polymerized actin in over half of the cells after 24 h. In contrast, macrophages infected with the
spvB
or SPI2 (
ssaV
or
ssaJ
) mutant strain retained normal F-actin filaments, despite similar numbers of intracellular bacteria. We conclude that SpvB and a functional SPI2 TTSS are essential for
Salmonella
-induced delayed cytotoxicity of human macrophages.
The Furin Inhibitor Hexa-d-Arginine Blocks the Activation ofPseudomonas aeruginosaExotoxin A In Vivo
Authors: Sarac Miroslav S. , Cameron Angus , Lindberg Iris 
Published: November 2002

ABSTRACTThePseudomonas aeruginosaexotoxin A (PEA) protein requires furin-mediated cleavage for manifestation of toxicity. We show here that the small stable furin inhibitor hexa-d-arginine amide effectively blocks PEA-induced cell lysis and is itself noncytotoxic. Administration of hexa-d-arginine to PEA-treated mice significantly improves their survival rate and also decreases circulating levels of tumor necrosis factor alpha.
Gene Discovery in the Freshwater Fish Parasite
Trypanosoma carassii
: Identification of
trans
-Sialidase-Like and Mucin-Like Genes
Authors: Agüero Fernán , Campo Vanina , Cremona Laura , Jäger Adriana , Di Noia Javier M. , Overath Peter , Sánchez Daniel O. , Frasch Alberto Carlos 
Published: November 2002

ABSTRACT

A total of 1,921 expressed sequence tags (ESTs) were obtained from bloodstream trypomastigotes of
Trypanosoma carassii
, a parasite of economic importance due to its high prevalence in fish farms. Analysis of the data set allowed us to identify a
trans
-sialidase (TS)-like gene and three ESTs coding for putative mucin-like genes. TS activity was detected in cell extracts of bloodstream trypomastigotes. We have also used the sequence information obtained to identify genes that have not been previously described in trypanosomatids. (Additional information on these ESTs can be found at
http://genoma.unsam.edu.ar/projects/tca
.)
Generalized Immunological Decline during Long-Term Experimental Infection withMycobacterium avium
Authors: Gilbertson Brad , Cheers Christina 
Published: November 2002

ABSTRACTTerminal loss of immune responsiveness in C57BL/10 mice intranasally infected withMycobacterium aviumwas observed in both spleen and lung. It was nonspecific and related to the duration of infection, not the age of the mice. While there was loss of total T cells, the remaining cells were less efficient at gamma interferon production.
Nasal Immunization with Homogenate and Peptide Antigens Induces Protective Immunity against
Trichinella spiralis
Authors: McGuire Carolann , Chan Weng C. , Wakelin Derek 
Published: November 2002

ABSTRACT

Mice were successfully immunized against the intestinal nematode
Trichinella spiralis
by intranasal administration of a 30-mer peptide antigen with cholera toxin B. Immunized mice developed antigen-specific serum immunoglobulin G1, intestinal immunoglobulin A, and a type 2-biased cytokine response. Intranasal immunization therefore generates the Th2-mediated responses required for immunity against intestinal parasites.
Cloning and Characterization of Genes Encoding Homologues of the B Subunit of Cholera Toxin and the
Escherichia coli
Heat-Labile Enterotoxin from Clinical Isolates of
Citrobacter freundii
and
E. coli
Authors: Karasawa Tadahiro , Ito Hideaki , Tsukamoto Teizo , Yamasaki Shinji , Kurazono Hisao , Faruque Shah M. , Nair G. Balakrish , Nishibuchi Mitsuaki , Takeda Yoshifumi 
Published: November 2002

ABSTRACT

We identified and characterized a gene encoding a homologue of the B subunits of cholera toxin (CTB) and heat-labile enterotoxin (LTB) of
Escherichia coli
from a clinical isolate of
Citrobacter freundii
that was found to produce a factor in the culture supernatant that cross-reacted with antibodies to CTB and LTB when assayed by enzyme-linked immunosorbent assay (ELISA). The gene encoding the ELISA-positive factor,
cfxB
, consisted of 375 nucleotides and was located downstream of an 852-nucleotide open reading frame,
cfxA
, with a 56-nucleotide intergenic space. The
cfxB
gene was predicted to encode a 125-amino-acid polypeptide, which had 73.8 and 72.8% identities with the amino acid sequences of LTB and CTB, respectively. However, the amino acid sequence of the deduced polypeptide CFXA had no homologies to those of the A subunits of CT or LT. DNA probes developed from the sequences of
cfxA
and
cfxB
were used to screen 67
C. freundii
isolates and 152
E. coli
isolates from diarrheal patients by colony blot hybridization. Two strains,
C. freundii
48 and
E. coli
176, reacted with both DNA probes under conditions of high stringency. We cloned homologues of the
cfxA
and
cfxB
genes from
E. coli
176 and designated them
ecxA
and
ecxB
, respectively. The
ecxA
gene and the
ecxB
gene comprise 855 and 375 nucleotides, respectively, with a 50-nucleotide intergenic space, and encode a 285- and a 125-amino-acid residue polypeptides, respectively. The results of the present study may provide important clues to the origin and evolution of immunologically related factors sharing a common enterotoxin-like A and B subunit structures.
IroN Functions as a Siderophore Receptor and Is a Urovirulence Factor in an Extraintestinal Pathogenic Isolate of
Escherichia coli
Authors: Russo Thomas A. , McFadden Catherine D. , Carlino-MacDonald Ulrike B. , Beanan Janet M. , Barnard Travis J. , Johnson James R. 
Published: November 2002

ABSTRACT

IroN was recently identified in the extracellular pathogenic
Escherichia coli
strain CP9. In this study experimental evidence demonstrating that IroN mediates utilization of the siderophore enterobactin was obtained, thereby establishing IroN as a catecholate siderophore receptor. In a mouse model of ascending urinary tract infection the presence of
iroN
contributed significantly to CP9's ability to colonize the mouse bladder, kidneys, and urine, evidence that IroN is a urovirulence factor. However, growth in human urine ex vivo and adherence to uroepithelial cells in vitro were equivalent for an isogenic mutant deficient in IroN (CP82) and its wild-type parent (CP9). Taken together, these findings establish that IroN is a siderophore receptor and a urovirulence factor. However, uncertainty exists as to the mechanism(s) via which IroN contributes to urovirulence.
Neuraminidase Expressed by
Streptococcus pneumoniae
Desialylates the Lipopolysaccharide of
Neisseria meningitidis
and
Haemophilus influenzae
: a Paradigm for Interbacterial Competition among Pathogens of the Human Respiratory Tract
Authors: Shakhnovich Elizabeth A. , King Samantha J. , Weiser Jeffrey N. 
Published: November 2002

ABSTRACT

Both
Neisseria meningitidis
and
Haemophilus influenzae
are capable of mimicking host structures by decorating their lipopolysaccharides with sialic acid. We show that a neuraminidase expressed by
Streptococcus pneumoniae
(NanA) is able to desialylate the cell surfaces of both these species, which reside in and possibly compete for the same host niche.
Rough Lipopolysaccharide from
Brucella abortus
and
Escherichia coli
Differentially Activates the Same Mitogen-Activated Protein Kinase Signaling Pathways for Tumor Necrosis Factor Alpha in RAW 264.7 Macrophage-Like Cells
Authors: Jarvis Bruce W. , Harris Tajie H. , Qureshi Nilofer , Splitter Gary A. 
Published: November 2002

ABSTRACT

The intracellular, gram-negative pathogen
Brucella abortus
establishes chronic infections in host macrophages while downregulating cytokines such as tumor necrosis factor alpha (TNF-α). When producing TNF-α,
Brucella abortus
rough lipopolysaccharide (LPS) activates the same mitogen-activated protein kinase signaling pathways (ERK and JNK) as
Escherichia coli
LPS, but
Brucella
LPS is a much less potent agonist.
Inhibition of
Neisseria gonorrhoeae
by
Lactobacillus
Species That Are Commonly Isolated from the Female Genital Tract
Authors: St. Amant Diane C. , Valentin-Bon Iris E. , Jerse Ann E. 
Published: November 2002

ABSTRACT

Epidemiological studies suggest H
2
O
2
-producing lactobacilli protect women against gonorrhea. Here we demonstrate that
Lactobacillus crispatus
and
Lactobacillus jensenii
, the most common lactobacilli in the female genital tract, inhibit gonococci in both acidic and neutral pH conditions. Inhibition was neutralized by bovine catalase, suggesting that H
2
O
2
is the primary mediator of inhibition.
Leptospires Are Killed In Vitro by Both Oxygen-Dependent and -Independent Reactions
Authors: Murgia Rossella , Garcia Rodolfo , Cinco Marina 
Published: November 2002

ABSTRACT

This study reports for the first time that leptospires are killed by H
2
O
2
and by low-molecular-weight primary granule components, which are agents normally released by neutrophils upon stimulation. Although both pathogenic and nonpathogenic strains were sensitive to H
2
O
2
-mediated killing, nonpathogenic organisms were found to be more susceptible. In addition, the killing of leptospires by H
2
O
2
was found to be independent of the presence of the neutrophil primary granule component myeloperoxidase and therefore not a consequence of halogenation reactions. We have also determined that leptospires are significantly sensitive only to primary granule components and, among those, to proteins and/or peptides of less than 30 kDa.
PeptidoglycanN-Acetylglucosamine Deacetylase, a Putative Virulence Factor inStreptococcus pneumoniae
Authors: Vollmer Waldemar , Tomasz Alexander 
Published: November 2002

ABSTRACTMany glucosamine residues of the pneumococcal peptidoglycan (PG) are not acetylated, which makes the PG resistant to lysozyme. A capsular type III mutant with an inactivatedpgdAgene (encoding the peptidoglycanN-acetylglucosamine deacetylase A) became hypersensitive to exogenous lysozyme and showed reduced virulence in the intraperitoneal mouse model.
Expression of NADPH Oxidase-Dependent Resistance to Listeriosis in Mice Occurs during the First 6 to 12 Hours of Liver Infection
Authors: LaCourse Ronald , Ryan Lynn , North Robert J. 
Published: November 2002

ABSTRACTWild-type mice inoculated withListeria monocytogenesintravenously were capable of reducing the bacterial load in their livers by 90% within 6 h. In contrast, mice with deletions of the gene for NADPH oxidase were incapable of expressing this early oxygen-dependent anti-Listeriadefense and consequently showed higher levels of liver infection at later times.
Plasmodium falciparum
Serine Repeat Protein, a New Target of Monocyte-Dependent Antibody-Mediated Parasite Killing
Authors: Soe Soe , Singh Subhash , Camus Daniel , Horii Toshihiro , Druilhe Pierre 
Published: November 2002

ABSTRACT

Using monoclonal antibodies and human affinity-purified antibodies specific to the
Plasmodium falciparum
126-kDa serine-rich protein, SERP, we found that these antibodies have no direct effect upon merozoite invasion at the concentrations tested but can cooperate with blood monocytes to strongly inhibit
P. falciparum
in vitro growth.