bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential Expression of Cytokine Genes and Inducible Nitric Oxide Synthase Induced by Opacity Phenotype Variants ofStreptococcus pneumoniaeduring Acute Otitis Media in the Rat
Authors: Long J. P. , Tong H. H. , Shannon P. A. , DeMaria T. F. 
Published: September 2003

ABSTRACTPhase variation in the colonial opacity phenotype ofStreptococcus pneumoniaehas been implicated as a factor in bacterial adherence, colonization, and invasion in the pathogenesis of pneumococcal otitis media (OM). The purpose of this study was to determine whetherS. pneumoniaeopacity variants influence the induction of gene expression for proinflammatory mediators in vivo using the rat model of OM. Both the opaque and transparent phenotype variants induced a significant up-regulation in gene expression for interleukin-1α (IL-1α), IL-1β, IL-6, IL-10, tumor necrosis factor alpha, and inducible nitric oxide synthase (iNOS) compared to saline sham-inoculated controls at both 4 and 24 h postinoculation (P< 0.05 in all cases). Furthermore, whereas a significant difference in gene expression was evident for only IL-6 (greater following challenge with the opaque variant) and IL-1β (greater following challenge with the transparent variant) at 4 h, by 24 h the opaque variant cohort demonstrated a significant increase in gene expression for IL-1α, IL-1β, IL-6, IL-10, and iNOS relative to animals inoculated with the transparent phenotype variant (P< 0.05 in all cases). Enzyme-linked immunosorbent assay results confirmed the gene expression data as determined by real-time PCR. Moreover, the concentrations of the opaque variant in the middle ear lavage fluid were a full log higher than those of the transparent variant. The aforementioned results indicate that the opaque phenotype variant is more efficient at survival and multiplication within the middle ear space, resulting in the accumulation of more inflammatory cells and the enhanced expression and production of inflammatory mediators. However, when the data were normalized to account for differences in middle ear bacterial titers, it became apparent that the transparent variant ofS. pneumoniaeis a more potent inducer of inflammation, triggering the accumulation of more inflammatory cells and substantially greater fold increases in the expression and production of inflammatory mediators. Data from this study indicate thatS. pneumoniaeopacity variants influence the temporal mRNA expression of inflammatory mediators within the middle ear.
Pneumococcal Lipoteichoic Acid (LTA) Is Not as Potent as Staphylococcal LTA in Stimulating Toll-Like Receptor 2
Authors: Han Seung Hyun , Kim Je Hak , Martin Michael , Michalek Suzanne M. , Nahm Moon H. 
Published: September 2003

ABSTRACTStreptococcus pneumoniaeis a leading cause of gram-positive sepsis, and lipoteichoic acid (LTA) may be important in causing gram-positive bacterial septic shock. Even though pneumococcal LTA is structurally distinct from the LTA of other gram-positive bacteria, the immunological properties of pneumococcal LTA have not been well characterized. We have investigated the ability of LTAs to stimulate human monocytes by using highly pure and structurally intact preparations of pneumococcal LTA and its two structural variants. The variants were pneumococcal LTA with only one acyl chain (LTA-1) and completely deacylated LTA (LTA-0). The target cells used in the study were peripheral blood mononuclear cells (PBMCs) and two model cell lines (CHO/CD14/TLR2 and CHO/CD14/TLR4) that express human CD25 protein in response to Toll-like receptor 2 (TLR2) and TLR4 stimulation, respectively. Intact pneumococcal LTA and LTA-1 stimulated PBMC and CHO/CD14/TLR2 cells in a dose-dependent manner but did not stimulate CHO/CD14/TLR4 cells. Pneumococcal LTA was about 100-fold less potent thanStaphylococcus aureusLTA in stimulating the CHO/CD14/TLR2 cells and PBMCs. LTA-0 (or pneumococcal teichoic acid) stimulated neither CHO/CD14/TLR2 nor CHO/CD14/TLR4 cells even at high concentrations. Excess teichoic acid, LTA-0, antibodies to phosphocholine, or antibodies to TLR4 did not inhibit the LTA-induced TLR2 stimulation. However, antibodies to CD14, TLR1, or TLR2 suppressed tumor necrosis factor alpha (TNF-α) production by PBMCs in response to LTA or LTA-1. These results suggest that pneumococcal LTA with one or both acyl chains stimulates PBMCs primarily via TLR2 with the help of CD14 and TLR1.
Immunogenicity of, and Immunologic Memory to, a Reduced Primary Schedule of Meningococcal C-Tetanus Toxoid Conjugate Vaccine in Infants in the United Kingdom
Authors: Borrow Ray , Goldblatt David , Finn Adam , Southern Joanna , Ashton Lindsey , Andrews Nick , Lal Gouri , Riley Christine , Rahim Rukhsana , Cartwright Keith , Allan Geraldine , Miller Elizabeth 
Published: September 2003

ABSTRACTIt has been previously shown that one of the three meningococcal C conjugate (MCC) vaccines introduced in the United Kingdom proved highly immunogenic after the first dose of a three-dose schedule, with evidence of immune memory after dose 3. Thus, in infants a one- or two-dose schedule of this MCC vaccine, conjugated to tetanus toxoid (TT), may suffice. Healthy infants (n= 586) were randomized to receive either one (group 1), two (group 2), or three (group 3) doses of MCC-TT vaccine with a 10-μg polysaccharide booster given at 13 to 14 months of age. Serum bactericidal antibody (SBA) levels were measured by utilizing rabbit complement (rSBA), meningococcal C-specific immunoglobulin G (IgG), and avidity indices (AIs). For groups 1, 2, and 3, the percentages of infants with an rSBA level of ≥8 against strain C11 were 98.4, 100, and 99.4%, respectively. Infants in group 1 with prevaccination rSBA titers of ≥8 had post-primary MCC rSBA geometric mean titers (GMTs) significantly lower than those infants with prevaccination rSBA titers of <8. One dose of MCC-TT vaccine given to infants at 2 months of age yielded significantly lower SBA GMTs and geometric mean AIs (GMAIs) than two or three doses but elicited a significantly greater response after boosting, as reflected by rSBA levels and GMAI. This study provides the first evidence that the number of doses of MCC-TT used in infant immunization schedules could be decreased.
The Urokinase Receptor Can Be Induced byBorrelia burgdorferithrough Receptors of the Innate Immune System
Authors: Coleman James L. , Benach Jorge L. 
Published: September 2003

ABSTRACTMonocytic cells exposed toBorrelia burgdorferi, through unknown receptors, overexpress the urokinase receptor (uPAR), a key mediator of the plasminogen activation system. We show that combined blockade of CD14 and TLR2 causes a significant inhibition ofB. burgdorferi-induced uPAR in Mono Mac 6 (MM6) cells. Other pattern recognition receptors tested (CD11b/CD18, the mannose receptor, and theN-formyl-methionyl-leucyl-phenylalanine receptor) did not have demonstrated roles inB. burgdorferi-mediated uPAR induction. We dissected the result for CD14 andTLR2 by investigating the singular contributions of each. Independent functional blockade of CD14 or TLR2 failed to inhibitB. burgdorferi-mediated uPAR induction. 1,25-Dihydroxyvitamin D3differentiation of MM6 cells increased CD14 expression 12-fold but did not augmentB. burgdorferi-mediated uPAR expression. Peritoneal exudate macrophages (PEM) from CD14- or TLR2-deficient mice were not defective inB. burgdorferi-mediated synthesis of uPAR mRNA and protein. Increased uPAR mRNA or protein or both were apparent in PEM from transgenic and control mice, even at a ratio of oneBorreliaspirochete per cell. We conclude that signaling for the uPAR response, as mediated byB. burgdorferi, proceeds with CD14 and TLR2 as partial contributors. That part under control of CD14 and TLR2 represents a new link between the host plasminogen activation and innate immunity systems.
Mucin Degradation Mechanisms by DistinctPseudomonas aeruginosaIsolates In Vitro
Authors: Aristoteli Lina Panayiota , Willcox Mark D. P. 
Published: September 2003

ABSTRACTPseudomonas aeruginosahas emerged as an important causative agent of bacterial keratitis, a rapidly progressive ocular condition that may result in blindness. Secretory mucin forms the main constituent of the precorneal tear film, a three-layer film on the ocular surface protecting the underlying corneal epithelium from potential pathogens. The purpose of the present study was to compare mucin degradation mechanisms between ocularP. aeruginosastrains. Mucin degradation was assessed by agarose electrophoresis, lectin blotting, and size exclusion chromatography. The results indicate that certainP. aeruginosastrains (Paer12, ATCC 15442, 6294, and Paer25) had depleted mucin from the culture supernatant and that this was contingent on the inherent ability of these isolates to produce proteases. Non-protease-producing strains (Paer1 and Paer3) did not appreciably degrade mucin. Further, galactosidase,N-acetylglucosaminidase, andN-acetylgalactosaminidase activities were detected in some strains, suggesting the operation of further mechanisms of mucin degradation byP. aeruginosa. Mucin degradation byP. aeruginosaalso seemed to be for the acquisition of nutrients, as a growth advantage was observed in mucin-depleting strains over nondepleting strains in the long term. It is postulated that the degradation of mucin serves to collapse the mucin barrier and its associated network containing antibacterial tear components and to provide energy for sustained bacterial growth.
A Gonococcal Efflux Pump System Enhances Bacterial Survival in a Female Mouse Model of Genital Tract Infection
Authors: Jerse Ann E. , Sharma Nirmala D. , Simms Amy N. , Crow Emily T. , Snyder Lori A. , Shafer William M. 
Published: September 2003

ABSTRACT

Active efflux of antimicrobial substances is likely to be an important bacterial defense against inhibitory host factors inherent to different body sites. Two well-characterized multidrug resistance efflux systems (MtrCDE and FarAB-MtrE) exist in
Neisseria gonorrhoeae
, a bacterial pathogen of the human genital mucosae. In vitro studies suggest that the MtrCDE and FarAB-MtrE efflux systems protect the gonococcus from hydrophobic antimicrobial substances that are likely to be present on mucosal surfaces. Here we report that a functional MtrCDE efflux system, but not a functional FarAB-MtrE system, enhances experimental gonococcal genital tract infection in female mice. Specifically, the recovery of
mtrD
and
mtrE
mutants, but not a
farB
mutant, from mice inoculated with mutant or wild-type gonococci was reduced compared with that of the wild-type strain. Competitive-infection experiments confirmed the survival disadvantage of MtrCDE-deficient gonococci. This report is the first direct evidence that a multidrug resistance efflux system enhances survival of a bacterial pathogen in the genital tract. Additionally, experiments using ovariectomized mice showed that MtrCDE-deficient gonococci were more rapidly cleared from mice that were capable of secreting gonadal hormones. MtrCDE-deficient gonococci were more sensitive to nonphysiological concentrations of progesterone in vitro than were wild-type or FarAB-MtrE-deficient gonococci. These results suggest that progesterone may play an inhibitory role in vivo. However, hormonally regulated factors rather than progesterone itself may be responsible for the more rapid clearance of
mtr
-deficient gonococci from intact mice.
The Global Regulator ArcA Modulates Expression of Virulence Factors in
Vibrio cholerae
Authors: Sengupta Nilanjan , Paul Kalidas , Chowdhury Rukhsana 
Published: September 2003

ABSTRACT

A
Vibrio cholerae arcA
mutant was constructed and used to examine the role of the global anaerobiosis response regulator ArcA in the expression of virulence factors in this important human pathogen. In
V. cholerae
, expression of the major virulence factors cholera toxin (CT) and toxin-coregulated pilus (TCP) is regulated by the transcriptional activator ToxT.
toxT
expression, in turn, is controlled by the transmembrane DNA binding proteins ToxR and TcpP. In the
V. cholerae arcA
mutant, although ToxR and TcpP were unaffected, Northern blot and reverse transcription-PCR analyses indicated that the expression of
toxT
was significantly decreased with concomitant reduction in the expression of CT and TCP. CT and TCP expression was completely restored in the
V. cholerae arcA
mutant strain by expressing a cloned
toxT
gene in the mutant. These results suggest that ArcA functions as a positive regulator of
toxT
expression under both aerobic and anaerobic conditions, although as expected, the effect was more pronounced during anaerobic growth. This was reflected in a reduction of virulence of the
V. cholerae arcA
mutant strain in the infant mouse cholera model.
Activation of Human Dendritic Cells Is Modulated by Components of the Outer Membranes ofNeisseria meningitidis
Authors: Al-Bader Tamara , Christodoulides Myron , Heckels John E. , Holloway Judith , Semper Amanda E. , Friedmann Peter S. 
Published: September 2003

ABSTRACTNeisseria meningitidisserogroup B is a major cause of life-threatening meningitis and septicemia worldwide, and no effective vaccine is available. Initiation of innate and acquired immune responses toN. meningitidisis likely to be dependent on cellular responses of dendritic cells (DC) to antigens present in the outer membrane (OM) of the meningococcus. In this study, the responses of human monocyte-derived DC (mo-DC) to OM isolated from parent (lipopolysaccharide [LPS]-replete) meningococci and from a mutant deficient in LPS were investigated. Parent OM selectively up-regulated Toll-like receptor 4 (TLR4) mRNA expression and induced mo-DC maturation, as reflected by increased production of chemokines, proinflammatory cytokines, and CD83, CD80, CD86, CD40, and major histocompatibility complex (MHC) class II molecules. In contrast, LPS-deficient OM selectively up-regulated TLR2 mRNA expression and induced moderate increases in both cytokine production and expression of CD86 and MHC class II molecules. Preexposure to OM, with or without LPS, augmented the allostimulatory properties of mo-DC, which induced proliferation of naive CD4+CD45RA+T cells. In addition, LPS-replete OM induced a greater gamma interferon/interleukin-13 ratio in naive T cells, whereas LPS-deficient OM induced the reverse profile. These data demonstrate that components of the OM, other than LPS, are also likely to be involved in determining the levels of DC activation and the nature of the T-helper immune response.
Augmentation ofActinobacillus actinomycetemcomitansInvasion of Human Oral Epithelial Cells and Up-Regulation of Interleukin-8 Production by Saliva CD14
Authors: Takayama Atsuko , Satoh Aya , Ngai Tomoko , Nishimura Takashi , Ikawa Keiji , Matsuyama Takami , Shimauchi Hidetoshi , Takada Haruhiko , Sugawara Shunji 
Published: September 2003

ABSTRACTIt has recently been shown that human salivary glands constitutively express CD14, an important molecule in innate immunity, and that a soluble form of CD14 is secreted in saliva. The concentration of CD14 in parotid (a serous gland) saliva was comparable to that in normal serum and 10-fold the amount in whole saliva, although the physiological function of saliva CD14 remained unclear.Actinobacillus actinomycetemcomitansis a periodontopathic bacterium and is able to invade oral epithelial cells. The present study showed that upon exposure to liveA. actinomycetemcomitansY4 for 2 h, human oral epithelial HSC-2 cells produced interleukin-8 (IL-8) for a further 24 h and whole saliva augmented the production induced byA. actinomycetemcomitansY4. Parotid saliva showed a more pronounced effect on the production of IL-8 than whole saliva. Neither saliva preparation itself had IL-8-inducing activity. Parotid saliva exhibited antibacterial activity against a low concentration ofA. actinomycetemcomitansY4, but recombinant CD14 did not show the activity. The internalization ofA. actinomycetemcomitansY4 into HSC-2 cells was inhibited by cytochalasin B, indicating that the process was actin dependent, and depletion of CD14 from parotid saliva inhibited the invasion and, as a consequence, inhibited production of IL-8. Furthermore, human recombinant CD14 augmented invasion and IL-8 production. These results suggest that saliva CD14 promoted the invasion of oral epithelial cells byA. actinomycetemcomitansand consequently augmented the production of IL-8, playing an important role in innate immunity in the oral cavity.
Protection against Syphilis Correlates with Specificity of Antibodies to the Variable Regions ofTreponema pallidumRepeat Protein K
Authors: Morgan Cecilia A. , Lukehart Sheila A. , Van Voorhis Wesley C. 
Published: September 2003

ABSTRACTSyphilis has been recognized as a disease since the late 1400s, yet there is no practical vaccine available. One impediment to the development of a vaccine is the lack of understanding of multiple reinfections in humans despite the development of robust immune responses during the first episode. It has been shown that theTreponema pallidumrepeat protein K (TprK) differs in seven discrete variable (V) regions in isolates and that the antibody response during infection is directed to these V regions. Immunization with TprK confers significant protection against infection with the homologous strain. We hypothesize that the antigenic diversity of TprK is involved in immune evasion, which contributes to the lack of heterologous protection. Here, using the rabbit model, we show a correlation between limited heterologous protection andtprKdiversity in the challenge inoculum. We demonstrate that antibody responses to the V regions of one TprK molecule show limited cross-reactivity with heterologous TprK V regions.
Presence of Active Aliphatic Amidases in
Helicobacter
Species Able To Colonize the Stomach
Authors: Bury-Moné Stéphanie , Skouloubris Stéphane , Dauga Catherine , Thiberge Jean-Michel , Dailidiene Daiva , Berg Douglas E. , Labigne Agnès , De Reuse Hilde 
Published: September 2003

ABSTRACT

Ammonia production is of great importance for the gastric pathogen
Helicobacter pylori
as a nitrogen source, as a compound protecting against gastric acidity, and as a cytotoxic molecule. In addition to urease,
H. pylori
possesses two aliphatic amidases responsible for ammonia production: AmiE, a classical amidase, and AmiF, a new type of formamidase. Both enzymes are part of a regulatory network consisting of nitrogen metabolism enzymes, including urease and arginase. We examined the role of the
H. pylori
amidases in vivo by testing the gastric colonization of mice with
H. pylori
SS1 strains carrying mutations in
amiE
and/or
amiF
and in coinfection experiments with wild-type and double mutant strains. A new cassette conferring resistance to gentamicin was used in addition to the kanamycin cassette to construct the double mutation in strain SS1. Our data indicate that the amidases are not essential for colonization of mice. The search for
amiE
and
amiF
genes in 53
H. pylori
strains from different geographic origins indicated the presence of both genes in all these genomes. We tested for the presence of the
amiE
and
amiF
genes and for amidase and formamidase activities in eleven
Helicobacter
species. Among the gastric species,
H. acinonychis
possessed both
amiE
and
amiF
,
H. felis
carried only
amiF
, and
H. mustelae
was devoid of amidases.
H. muridarum
, which can colonize both mouse intestine and stomach, was the only enterohepatic species to contain
amiE
. Phylogenetic trees based upon the sequences of
H. pylori amiE
and
amiF
genes and their respective homologs from other organisms as well as the amidase gene distribution among
Helicobacter
species are strongly suggestive of amidase acquisition by horizontal gene transfer. Since amidases are found only in
Helicobacter
species able to colonize the stomach, their acquisition might be related to selective pressure in this particular gastric environment.
Enhanced CXC Chemokine Responses of Human Colonic Epithelial Cells to Locus of Enterocyte Effacement-Negative Shiga-Toxigenic
Escherichia coli
Authors: Rogers Trisha J. , Paton Adrienne W. , McColl Shaun R. , Paton James C. 
Published: September 2003

ABSTRACT

There is increasing evidence that by facilitating translocation of Shiga toxin (Stx) across the intestinal epithelium and by transporting bound toxin to remote sites such as the renal endothelium, polymorphonuclear leukocytes (PMNs) play a key role in the pathogenesis of Shiga-toxigenic
Escherichia coli
(STEC) disease. Plasma levels of PMN-attracting CXC chemokines such as interleukin-8 (IL-8) also appear to correlate in humans with the severity of disease. Thus, the capacity of STEC strains to elicit CXC chemokine responses in intestinal epithelial cells may be a crucial step in pathogenesis. Accordingly, we attempted to determine which STEC factors are responsible for CXC chemokine induction in human colonic epithelial cells. Infection of Hct-8 cells with locus for enterocyte effacement (LEE)-negative STEC strains isolated from patients with severe STEC disease resulted in up-regulation of IL-8, macrophage inflammatory protein 2α (MIP-2α), MIP-2β, and ENA-78 mRNA significantly higher and earlier than that elicited by several LEE-positive STEC strains, including the O157:H7 strain EDL933. Similarly, levels of IL-8 protein in LEE-negative STEC-infected Hct-8 culture supernatants were significantly higher than in LEE-positive STEC-infected culture supernatants. The difference in responses could not be attributed to the expression or nonexpression of LEE genes, the presence or absence of an STEC megaplasmid, or differences in O serogroups or in the type or amount of Stx produced. Interestingly, however, several of the LEE-negative STEC strains eliciting the strongest chemokine responses belonged to flagellar serotype H21. Incubation of Hct-8 cells with isolated H21 flagellin elicited IL-8 and MIP-2α responses similar to those seen in the presence of the most potent LEE-negative STEC strains. Deletion of the
fliC
gene, but not the
stx
2
gene, largely abolished the capacity of O113:H21 LEE-negative STEC strain 98NK2 to elicit IL-8 and MIP-2α responses in Hct-8 cells. Taken together, these data suggest that although Stx is capable of inducing CXC chemokine responses, the elevated responses seen in cells infected with certain STEC strains are largely attributable to the production of flagellin.
TheluxSGene ofStreptococcus pyogenesRegulates Expression of Genes That Affect Internalization by Epithelial Cells
Authors: Marouni Mehran J. , Sela Shlomo 
Published: September 2003

ABSTRACTThe gram-positive pathogenStreptococcus pyogeneswas recently reported to possess a homologue of theluxSgene that is responsible for the production of autoinducer 2, which participates in quorum sensing of both gram-positive and gram-negative bacteria. To test the effect of LuxS on streptococcal internalization, a LuxS mutant was constructed in strain SP268, an invasive M3 serotype. Functional analysis of the mutant revealed that it was internalized by HEp-2 cells with higher efficiency than the wild type (wt). Several genes, includinghasA(hyaluronic acid synthesis),speB(streptococcal pyrogenic exotoxin B), andcsrR(capsule synthesis regulator), a part of a two-component regulatory system, are known to affect the internalization of strain SP268 (J. Jadoun, O. Eyal, and S. Sela, Infect. Immun.70:462-469, 2002). Therefore, the expression of these genes in the mutant and in the wt was examined. LuxS mutation significantly reduced the mRNA level ofspeBand increased the mRNA level ofemm3. No substantial effect was observed on transcription ofhasAandcsrR. Yet less hyaluronic acid capsule was expressed in the mutant. Further analysis revealed thatluxSis under the regulation of the two-component global regulator CsrR. Our results indicate that LuxS activity in strain SP268 plays an important role in the expression of virulence factors associated with epithelial cell internalization.