bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Program of Macrophage Gene Expression Induced by Phagocytosis ofLeishmania chagasi
Authors: Rodriguez Nilda E. , Chang Haeok K. , Wilson Mary E. 
Published: March 2004

ABSTRACTLeishmaniaspp. are protozoans that survive and replicate intracellularly in mammalian macrophages. Antileishmanial immunity requires gamma interferon (IFN-γ)-mediated macrophage activation and generation of microbicidal effector molecules. The presence of intracellularLeishmaniasp. impairs macrophage responses to IFN-γ, which has led to the description of macrophages as deactivated. It has recently become apparent that in addition to classical activation, macrophages can be activated by distinct triggers to express noninflammatory or anti-inflammatory genes. These nonclassical activation programs have been called alternative or type II pathways. We hypothesized that during initial contact with a phagocyte, leishmaniae activate one of these nonclassical pathways, resulting in expression of genes whose products suppress microbicidal responses. Using DNA microarrays, we studied gene expression in RNAs from BALB/c bone marrow macrophages with and withoutLeishmania chagasiinfection. Some changes were verified by an RNase protection assay, reverse transcription-PCR, immunoblotting, or a bioassay. The pattern of genes activated by leishmania phagocytosis differed from the pattern of genes activated by bacteria or lipopolysaccharide and IFN-γ. Genes encoding some proinflammatory cytokines, receptors, and Th1-type immune response genes were down-modulated, and some genes associated with anti-inflammatory or Th2-like immune responses were up-regulated. Nonetheless, some markers of alternative (arginase) or type II activation (interleukin-10, tumor necrosis factor alpha) were unchanged. These data suggest that macrophages infected withL. chagasiexhibit a hybrid activation profile that is more characteristic of alternative or type II activation than of classical activation but does not strictly fall into either of these categories. We speculate that the pattern of genes upregulated by leishmania phagocytosis optimizes the chance of parasite survival in this hostile environment.
Cell Surface-Associated Elongation Factor Tu Mediates the Attachment of
Lactobacillus johnsonii
NCC533 (La1) to Human Intestinal Cells and Mucins
Authors: Granato Dominique , Bergonzelli Gabriela E. , Pridmore Raymond David , Marvin Laure , Rouvet Martine , Corthésy-Theulaz Irène E. 
Published: March 2004

ABSTRACT

The aim of this work was to identify
Lactobacillus johnsonii
NCC533 (La1) surface molecules mediating attachment to intestinal epithelial cells and mucins. Incubation of Caco-2 intestinal epithelial cells with an
L. johnsonii
La1 cell wall extract led to the recognition of elongation factor Tu (EF-Tu) as a novel La1 adhesin-like factor. The presence of EF-Tu at the surface of La1 was confirmed by analysis of purified outer surface protein extract by immunoblotting experiments, by electron microscopy, and by enzyme-linked immunosorbent assays of live bacteria. Furthermore, tandem mass spectrometry analysis proved that EF-TU was expressed at the La1 surface as an intact molecule. Using recombinant La1 EF-Tu protein, we were able to determine that its binding to intestinal cells and to mucins is pH dependent. Competition experiments suggested that EF-Tu has an important role in La1 mucin binding capacity. In addition, immunomodulation studies performed on HT29 cells showed that EF-Tu recombinant protein can induce a proinflammatory response in the presence of soluble CD14. Our in vitro results indicate that EF-Tu, through its binding to the intestinal mucosa, might participate in gut homeostasis.
Purification and Molecular Cloning of and Immunization with
Ancylostoma ceylanicum
Excretory-Secretory Protein 2, an Immunoreactive Protein Produced by Adult Hookworms
Authors: Bungiro Richard D. , Solis Carolina V. , Harrison Lisa M. , Cappello Michael 
Published: March 2004

ABSTRACT

Hookworms remain major agents of global morbidity, and vaccination against these bloodfeeding parasites may be an attractive complement to conventional control methods. Here we describe the cloning of
Ancylostoma ceylanicum
excretory-secretory protein 2 (AceES-2), a novel immunoreactive protein produced by adult worms. Native AceES-2 was purified from excretory-secretory (ES) products by reverse-phase high-pressure liquid chromatography, subjected to amino-terminal sequencing, and cloned from adult worm RNA by using reverse transcription-PCR. The translated AceES-2 cDNA predicts that the mature protein consists of 102 amino acids and has a molecular mass of 11.66 kDa. Western immunoblot and enzyme-linked immunosorbent assay analyses demonstrated that recombinant AceES-2 (rAceES-2) reacted strongly with antibodies from
A. ceylanicum
-infected hamsters. Immunization of hamsters with native ES products adsorbed to alum induced antibodies that recognized rAceES-2, while rAceES-2-alum vaccination resulted in antibodies that reacted with a single protein band in ES products that closely approximated the size predicted for the native molecule. Infected hamsters that were passively immunized with hyperimmune rabbit anti-rAceES-2 serum exhibited more rapid and complete recovery from anemia than controls that received normal serum. Oral immunization with rAceES-2 was associated with significantly reduced anemia upon challenge, an outcome similar to the outcome observed in hamsters that were orally vaccinated with soluble hookworm extract (the latter animals were also resistant to weight loss). These data suggest that AceES-2 plays an important role in the host-parasite interaction and that vaccination against this protein may represent a useful strategy for controlling hookworm anemia.
Molecular Characterization ofAncylostoma ceylanicumKunitz-Type Serine Protease Inhibitor: Evidence for a Role in Hookworm-Associated Growth Delay
Authors: Chu Daniel , Bungiro Richard D. , Ibanez Maureen , Harrison Lisa M. , Campodonico Eva , Jones Brian F. , Mieszczanek Juliusz , Kuzmic Petr , Cappello Michael 
Published: March 2004

ABSTRACTHookworm infection is a major cause of iron deficiency anemia and malnutrition in developing countries. TheAncylostoma ceylanicumKunitz-type inhibitor (AceKI) is a 7.9-kDa broad-spectrum inhibitor of trypsin, chymotrypsin, and pancreatic elastase that has previously been isolated from adult hookworms. Site-directed mutagenesis of the predicted P1 inhibitory reactive site amino acid confirmed the role of Met26in mediating inhibition of the three target serine proteases. By using reverse transcription-PCR, it was demonstrated that the level of AceKI gene expression increased following activation of third-stage larvae with serum and that the highest level of expression was reached in the adult stage of the parasite. Immunohistochemistry studies performed with polyclonal immunoglobulin G raised against recombinant AceKI showed that the inhibitor localized to the subcuticle of the adult hookworm, suggesting that it has a potential in vivo role in neutralizing intestinal proteases at the surface of the parasite. Immunization with recombinant AceKI was shown to confer partial protection against hookworm-associated growth delay without a measurable effect on anemia. Taken together, the data suggest that AceKI plays a role in the pathogenesis of hookworm-associated malnutrition and growth delay, perhaps through inhibition of nutrient absorption in infected hosts.
Role of Extracellular Phospholipases and Mononuclear Phagocytes in Dissemination of Cryptococcosis in a Murine Model
Authors: Santangelo Rosemary , Zoellner Hans , Sorrell Tania , Wilson Christabel , Donald Christine , Djordjevic Julianne , Shounan Yi , Wright Lesley 
Published: March 2004

ABSTRACT

Secreted phospholipase B (PLB) activity promotes the survival and replication of
Cryptococcus neoformans
in macrophages in vitro. We therefore investigated the role of mononuclear phagocytes and cryptococcal PLB in the dissemination of infection in a mouse model, using
C. neoformans
var.
grubii
wild-type strain H99, a
PLB1
deletion mutant (Δ
plb1
), and a reconstituted strain (Δ

plb1
rec

). PLB facilitated the entry of endotracheally administered cryptococci into lung IM. PLB was also required for lymphatic spread from the lung to regional lymph nodes and for entry into the blood. Langhans-type giant cells containing budding cryptococci were seen free in the lymphatic sinuses of hilar nodes of H99- and Δ

plb1
rec

-infected mice, suggesting that they may have a role in the dissemination of cryptococcal infection. The transfer of infected lung macrophages to recipient mice by tail vein injections demonstrated that these cells can facilitate hematogenous dissemination of cryptococci to the brain, independent of cryptococcal PLB secretion. PLB activities of cryptococci isolated from lung macrophages or infected brains were not persistently increased. We conclude that mononuclear phagocytes are a vehicle for cryptococcal dissemination and that PLB activity is necessary for the initiation of interstitial pulmonary infections and for dissemination from the lung via the lymphatics and blood. PLB is not, however, essential for the establishment of neurological infections when cryptococci are presented within, or after passage through, mononuclear phagocytes.
Probiotic Bifidobacteria Protect Mice from Lethal Infection with Shiga Toxin-Producing
Escherichia coli
O157:H7
Authors: Asahara Takashi , Shimizu Kensuke , Nomoto Koji , Hamabata Takashi , Ozawa Ayako , Takeda Yoshifumi 
Published: March 2004

ABSTRACT

The anti-infectious activity of probiotic Bifidobacteria against Shiga toxin-producing
Escherichia coli
(STEC) O157:H7 was examined in a fatal mouse STEC infection model. Stable colonization of the murine intestines was achieved by the oral administration of
Bifidobacterium breve
strain Yakult (naturally resistant to streptomycin sulfate) as long as the mice were treated with streptomycin in their drinking water (5 mg/ml). The pathogenicity of STEC infection, characterized by marked body weight loss and subsequent death, observed in the infected controls was dramatically inhibited in the
B. breve
-colonized group. Moreover, Stx production by STEC cells in the intestine was almost completely inhibited in the
B. breve
-colonized group. A comparison of anti-STEC activity among several
Bifidobacterium
strains with natural resistance to streptomycin revealed that strains such as
Bifidobacterium bifidum
ATCC 15696 and
Bifidobacterium catenulatum
ATCC 27539
T
did not confer an anti-infectious activity, despite achieving high population levels similar to those of effective strains, such as
B. breve
strain Yakult and
Bifidobacterium pseudocatenulatum
DSM 20439. The effective strains produced a high concentration of acetic acid (56 mM) and lowered the pH of the intestine (to pH 6.75) compared to the infected control group (acetic acid concentration, 28 mM; pH, 7.15); these effects were thought to be related to the anti-infectious activity of these strains because the combination of a high concentration of acetic acid and a low pH was found to inhibit Stx production during STEC growth in vitro.
Impairment of IntramacrophagicBrucella suisMultiplication by Human Natural Killer Cells through a Contact-Dependent Mechanism
Authors: Dornand Jacques , Lafont Virginie , Oliaro Jane , Terraza Annie , Castaneda-Roldan Elsa , Liautard Jean-Pierre 
Published: March 2004

ABSTRACTBrucellaspp. are facultative intracellular bacteria that can establish themselves and cause chronic disease in humans and animals. NK cells play a key role in host defense. They are implicated in an early immune response to a variety of pathogens. However, it was shown that they do not controlBrucellainfection in mice. On the other hand, NK cell activity is impaired in patients with acute brucellosis, and recently it was demonstrated that human NK cells mediate the killing of intramacrophagicMycobacterium tuberculosisin in vitro infection. Therefore, we have analyzed the behavior ofBrucella suisinfecting isolated human macrophages in the presence of syngeneic NK cells. We show that (i) NK cells impair the intramacrophagic development ofB. suis, a phenomenon enhanced by NK cell activators, such as interleukin-2; (ii) NK cells cultured in the presence of infected macrophages are highly activated and secrete gamma interferon and tumor necrosis factor alpha; (iii) impairment of bacterial multiplication inside infected cells is marginally associated with the cytokines produced during the early phase of macrophage-NK cell cocultures; (iv) direct cell-to-cell contact is required for NK cells to mediate the inhibition ofB. suisdevelopment; and (v) inhibition ofB. suisdevelopment results from an induction of NK cell cytotoxicity against infected macrophages. Altogether, these findings show that NK cells could participate early in controlling the intramacrophagic development ofB. suisin humans. It seems thus reasonable to hypothesize a role for NK cells in the control of human brucellosis. However, by impairing the activity of these cells in the acute phase of the illness, the pathogen should avoid this control.
Role for Moesin in Lipopolysaccharide-Stimulated Signal Transduction
Authors: Iontcheva Iveta , Amar Salomon , Zawawi Khalid H. , Kantarci Alpdogan , Van Dyke Thomas E. 
Published: March 2004

ABSTRACTMoesin is a 78-kDa protein with diverse functions in linking the cytoskeleton to the membrane while controlling cell shape, adhesion, locomotion, and signaling. The aim of this study was to characterize the expression and localization of moesin in mononuclear phagocytes by using confocal microscopy, flow cytometry, immunoprecipitation, and Western blotting and to analyze the function of moesin as a lipopolysaccharide receptor, utilizing an antisense oligonucleotide approach to knock down the moesin gene. Results revealed that moesin is expressed on the surface of monocytes/macrophages and surface expression is increased after lipopolysaccharide stimulation. The total protein mass of moesin is increased in monocytes after lipopolysaccharide stimulation. Immunoprecipitation showed that moesin coprecipitates with TLR4, a well-known lipopolysaccharide receptor, suggesting an early role of moesin in the formation of the initiation complex for lipopolysaccharide signaling. Two antisense and two control sense oligonucleotides were synthesized and introduced every 4 h for 48 h in adherent macrophage-like cells. Cells were then stimulated with lipopolysaccharide for 4 h, and the supernatants were assayed for tumor necrosis factor alpha (TNF-α) production. Cell lysates were assayed for moesin expression by Western blotting immediately after the 48-h treatment period and also after 116 h of recovery to assess the return of moesin expression and function. Moesin gene expression was completely suppressed after 48 h of incubation with antisense oligonucleotides. The antisense elimination of moesin gene expression led to a significant reduction of lipopolysaccharide-induced TNF-α secretion. Restoration of moesin gene expression led to restoration of TNF-α production. These data suggest an important role for moesin in lipopolysaccharide-induced TNF-α production, highlighting its importance in lipopolysaccharide-mediated signal transduction.
Plasmodium falciparum
Merozoite Surface Protein 6 Is a Dimorphic Antigen
Authors: Pearce J. Andrew , Triglia Tony , Hodder Anthony N. , Jackson David C. , Cowman Alan F. , Anders Robin F. 
Published: March 2004

ABSTRACT

Merozoite surface protein 1 (MSP1) is a highly polymorphic
Plasmodium falciparum
merozoite surface protein implicated in the invasion of human erythrocytes during the asexual cycle. It forms a complex with MSP6 and MSP7 on the merozoite surface, and this complex is released from the parasite around the time of erythrocyte invasion. MSP1 and many other merozoite surface proteins contain dimorphic elements in their protein structures, and here we show that MSP6 is also dimorphic. The sequences of eight
MSP6
genes indicate that the alleles of each dimorphic form of MSP6 are highly conserved. The smaller 3D7-type MSP6 alleles are detected in parasites from all malarious regions of the world, whereas K1-type MSP6 alleles have only been detected in parasites from mainland Southeast Asia. Cleavage of MSP6, which produces the p36 fragment in 3D7-type MSP6 and associates with MSP1, also occurs in K1-type MSP6 but at a different site in the protein. Anti-3D7 MSP6 antibodies weakly inhibited erythrocyte invasion by homologous 3D7 merozoites but did not inhibit a parasite line expressing the K1-type MSP6 allele. Antibodies from hyperimmune individuals affinity purified on an MSP3 peptide cross-reacted with MSP6; therefore, MSP6 may also be a target of antibody-dependent cellular inhibition.
Modulation of Enteropathogenic
Escherichia coli
Virulence by Quorum Sensing
Authors: Sircili Marcelo P. , Walters Matthew , Trabulsi Luis R. , Sperandio Vanessa 
Published: March 2004

ABSTRACT

Enteropathogenic
Escherichia coli
(EPEC) produces a lesion on epithelial cells called the attaching and effacing (AE) lesion. All genes necessary for AE are encoded within the locus of enterocyte effacement (LEE). EPEC also adheres in a characteristic pattern to epithelial cells by forming microcolonies, usually referred to as localized adherence (LA). LA is mediated by the bundle-forming pilus and flagella. The LEE genes are directly activated by the LEE-encoded regulator (Ler). Transcription of Ler is under the control of Per, integration host factor, Fis, BipA, and quorum sensing (QS), specifically through the
luxS
system. QS activates expression of the LEE genes in EPEC, with QseA activating transcription of
ler
. Here we report that transcription of the LEE genes and type III secretion are diminished in both
luxS
and
qseA
mutants. Transcription of the LEE genes is affected in both mutants mostly during the mid-exponential phase of growth. Transcription of
qseA
itself is diminished throughout growth in a
luxS
mutant and is under autorepression. Furthermore, QS activation of type III secretion is independent of
per
, given that QseA still activates type III secretion in a
per
mutant strain. Both mutants are deficient in adherence to epithelial cells and form smaller microcolonies. Several factors may contribute to this abnormal behavior: transcription of LEE genes and type III secretion are diminished, and expression of flagella and Per is altered in both mutants. These results suggest that QS is involved in modulating the regulation of the EPEC virulence genes.
The Hydrophobic Domain of the Mycobacterial Erp Protein Is Not Essential for the Virulence of
Mycobacterium tuberculosis
Authors: Kocíncová Dana , Sondén Berit , Bordat Yann , Pivert Elisabeth , de Mendonça-Lima Leila , Gicquel Brigitte , Reyrat Jean-Marc 
Published: March 2004

ABSTRACT

Erp (exported repetitive protein) is a member of a mycobacterium-specific family of extracellular proteins. A hydrophobic region that is localized at the C-terminal domain and that represents a quarter of the protein is highly conserved across species. Here we show that this hydrophobic region is not essential for restoring the virulence and tissue damage of an
erp
::
aph
mutant strain of
M. tuberculosis
as assessed by bacterial counts and lung histology analysis in a mouse model of tuberculosis.
Helicobacter pylori-Mediated Gastritis Induces Local Downregulation of Secretory Leukocyte Protease Inhibitor in the Antrum
Authors: Wex Thomas , Treiber Gerhard , Nilius Manfred , Vieth Michael , Roessner Albert , Malfertheiner Peter 
Published: March 2004

ABSTRACTHelicobacter pylori-infected subjects exhibited a strong decline in antral secretory leukocyte protease inhibitor (SLPI) levels compared toH. pylori-negative subjects and subjects from whomH. pylorihad been eradicated (P= 0.002). This reduction was specific for the antrum, whereas SLPI expression in corpus and duodenum was not affected. Antral SLPI levels were inversely correlated with inflammatory scores of antrum-predominant gastritis.
SKN7
of
Candida albicans
: Mutant Construction and Phenotype Analysis
Authors: Singh Praveen , Chauhan Neeraj , Ghosh Anup , Dixon Freddie , Calderone Richard 
Published: March 2004

ABSTRACT

The
SKN7
two-component response regulator gene of
Candida albicans
was deleted, and the phenotype of the mutant was established. This mutant exhibited impaired growth on Spider agar and 10% serum agar compared to wild-type and gene-reconstituted strains. The
skn7
mutant was sensitive to H
2
O
2
in vitro, but its virulence was only mildly attenuated. A comparison of the Skn7p and Ssk1p response regulators of
C. albicans
is discussed.
Genetic Control of Natural Resistance of Mouse Macrophages to
Coxiella burnetii
Infection In Vitro: Macrophages from Restrictive Strains Control Parasitophorous Vacuole Maturation
Authors: Zamboni Dario S. 
Published: March 2004

ABSTRACT

Macrophages from A/J and BALB/c mice were more susceptible to
Coxiella burnetii
phase II infection than were those from C57BL/6, C57BL/10, B10.A, C3H/HePas, and Swiss mice. Resistant macrophages effectively controlled the development of large replication vacuoles (LRVs), which accounted for the restriction of bacterial multiplication within the cultures. However, compared to fibroblasts, all macrophages controlled bacterial multiplication within LRVs.
Effect of Growth State on Transcription Levels of Genes Encoding Major Secreted Antigens of
Mycobacterium tuberculosis
in the Mouse Lung
Authors: Shi Lanbo , North Robert , Gennaro Maria Laura 
Published: March 2004

ABSTRACT

Arrest of the multiplication of
Mycobacterium tuberculosis
caused by expression of adaptive immunity in mouse lung was accompanied by a 10- to 20-fold decrease in levels of mRNAs encoding the secreted Ag85 complex and 38-kDa lipoprotein.
esat-6
mRNA levels were high throughout infection. The data imply that multiplying and nonreplicating tubercle bacilli have different antigen compositions.
Different Responses of Macrophages to Smooth and RoughBrucellaspp.: Relationship to Virulence
Authors: Jiménez de Bagüés María P. , Terraza Annie , Gross Antoine , Dornand Jacques 
Published: March 2004

ABSTRACTBy comparing smooth wild-typeBrucellastrains to their rough mutants, we show that the lipopolysaccharide (LPS) O side chain of pathogenicBrucellahas a dramatic impact on macrophage activation. It favors the development of virulentBrucellaby preventing the synthesis of immune mediators, important for host defense. We conclude that this O chain property is firmly linked toBrucellavirulence.
Enterococcal Aggregation Substance and Binding Substance Are Not Major Contributors to Urinary Tract Colonization by
Enterococcus faecalis
in a Mouse Model of Ascending Unobstructed Urinary Tract Infection
Authors: Johnson James R. , Clabots Connie , Hirt Helmut , Waters Christopher , Dunny Gary 
Published: March 2004

ABSTRACT

Isogenic
Enterococcus faecalis
strains that differ in their expression of aggregation substance (AS) and its cognate receptor, enterococcal binding substance (EBS), were compared for urovirulence in mice. Strain OG1SSp/pCF500 (inducible AS
+
, constitutive EBS
+
) failed to outcompete isogenic derivative INY3000 (AS
−
EBS
−
) in the urine, bladders, or kidneys of mice harvested at 48 h postinoculation. Neither mouse nor human urine induced AS expression by OG1SSp/pCF500. Recombinant strain OG1SSp/pINY1801 (constitutive AS
+
, EBS
+
) exhibited plasmid segregation that was as extensive in vivo as in vitro. These data suggest that AS and EBS do not contribute to upper or lower urinary tract colonization by
E. faecalis
and that growth in urine does not induce AS expression by strains carrying plasmids in the pCF10 family.