bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Regulatory Role for Interleukin 4 in Differential Inflammatory Responses in the Lung following Infection of Mice Primed with Th1- or Th2-Inducing Pertussis Vaccines
Authors: McGuirk Peter , Mills Kingston H. G. 
Published: July 2002

ABSTRACTProtection against infectious pathogens at mucosal surfaces is dependent on local antibody responses, production of inflammatory mediators, and recruitment of immune effector cells to the site of infection. Since Th1 and Th2 cells produce cytokines with pro- and anti-inflammatory activities, immunization with vaccines that induce these T-cell subtypes may regulate the subsequent inflammatory response to infection. We have demonstrated that immunization of mice with pertussis whole-cell or acellular vaccines (Pw or Pa) selectively induces Th1 and Th2 cells, respectively. In this study we have used a murine respiratory-infection model to demonstrate that priming with a Th1- or Th2-inducing pertussis vaccine can influence the local inflammatory response and immune effector cells in the lung following aerosol challenge withBordetella pertussis. Analysis of bronchoalveolar lavage (BAL) fluid taken during the course ofB. pertussisinfection of naı̈ve mice or mice immunized with Pw revealed an early influx of neutrophils and local production of interleukin 1β (IL-1β) in the lungs. In contrast, neutrophil infiltration and IL-1β production were not observed following challenge of mice immunized with the Th2-inducing Pa. Conversely, during infection local production of IL-6 and IL-1ra was significantly greater in mice immunized with Pa than in those immunized with Pw. Studies of knockout mice revealed neutrophil and lymphocyte infiltration in the lungs followingB. pertussisinfection of IL-4-defective (IL-4−/−) mice but not in wild-type mice immunized with Pa. Furthermore, the levels of IL-1β, IL-6, and IL-1ra in Pa-immunized IL-4−/−mice were comparable to those in mice immunized with Pw. These results demonstrate distinct influences of Th1- and Th2-inducing vaccines on the protective inflammatory responses in the lungs following challenge withB. pertussisand implicate IL-4 as an important regulator of inflammatory-cell recruitment.
Cell Specificity of
Helicobacter pylori
Cytotoxin Is Determined by a Short Region in the Polymorphic Midregion
Authors: Ji Xuhuai , Fernandez Thomas , Burroni Daniela , Pagliaccia Cristina , Atherton John C. , Reyrat Jean-Marc , Rappuoli Rino , Telford John L. 
Published: July 2002

ABSTRACT

There are two alleles of the vacuolating cytotoxin gene from
Helicobacter pylori
, which code for toxins with different cell specificities. By analyzing the phenotypes of natural and artificial chimeras between the two forms of the protein, we have delimited a short stretch of amino acids which determine the cell specificity.
A Functional
cra
Gene Is Required for
Salmonella enterica
Serovar Typhimurium Virulence in BALB/c Mice
Authors: Allen James H. , Utley Maryjane , van den Bosch Han , Nuijten Piet , Witvliet Maarten , McCormick Beth A. , Krogfelt Karen A. , Licht Tine Rask , Brown Derek , Mauel Michael , Leatham Mary P. , Laux David C. , Cohen Paul S. 
Published: July 2002

ABSTRACT

A minitransposon mutant of
Salmonella enterica
serovar Typhimurium SR-11, SR-11 Fad
−
, is unable to utilize gluconeogenic substrates as carbon sources and is avirulent and immunogenic when administered perorally to BALB/c mice (M. J. Utley et al., FEMS Microbiol. Lett., 163:129–134, 1998). Here, evidence is presented that the mutation in SR-11 Fad
−
that renders the strain avirulent is in the
cra
gene, which encodes the Cra protein, a regulator of central carbon metabolism.
Role of Pulmonary Alveolar Macrophages in Defense of the Lung againstPseudomonas aeruginosa
Authors: Cheung Dorothy O. Y. , Halsey Keith , Speert David P. 
Published: July 2002

ABSTRACTAlveolar macrophages (AM) provide one of the first lines of defense against microbial invasion in the lower airways. The role of AM in the clearance ofPseudomonas aeruginosain mice after intrapulmonary challenge was evaluated. AM were depleted by intranasal administration of liposome-encapsulated dichloromethylene diphosphonate. At 24 h following the instillation of liposomes, a sublethal dose ofP. aeruginosawas inoculated intranasally. Spleen, liver, and lung tissue was then evaluated for viable bacteria and for histopathology. AM depletion of 78 to 88% did not affect the survival rate of infected mice or clearance ofP. aeruginosafrom the spleen, liver, or lung, compared to the control group, but the mice's susceptibility toKlebsiella pneumoniaewas greatly enhanced. The recruitment of neutrophils to the lung was also not affected. Freshly explanted AM were not competent to phagocytose unopsonizedP. aeruginosabut were able to phagocytose zymosan particles. Further studies were conducted to assess the in situ phagocytic activities of AM. Three hours after the intranasal instillation ofP. aeruginosaor other particles, bronchoalveolar lavage was performed. AM phagocytosis of zymosan particles and latex beads exceeded that ofP. aeruginosa. Neutrophils were recruited to the lung in response to a high-dose bacterial challenge. These results suggest that AM do not play an important role in defense of the lung againstP. aeruginosa.
Coincubation of Human Spermatozoa with
Chlamydia trachomatis
In Vitro Causes Increased Tyrosine Phosphorylation of Sperm Proteins
Authors: Hosseinzadeh S. , Brewis I. A. , Pacey A. A. , Moore H. D. M. , Eley A. 
Published: July 2002

ABSTRACT

Elementary bodies (EBs) of the obligate intracellular bacterium
Chlamydia trachomatis
are responsible for the first step of attachment to host cells. We have studied the effects of EBs on human sperm protein tyrosine phosphorylation, which is important to sperm function. Indirect immunofluorescence using antiphosphotyrosine antibodies showed that serovar E, but not LGV, caused increased tyrosine phosphorylation which was localized to the sperm tail region. Immunoblotting revealed that serovar E caused a marked increase in tyrosine phosphorylation of 80- and 95-kDa sperm proteins, whereas serovar LGV caused increased phosphorylation of only the 80-kDa moiety. Considering the importance of tyrosine phosphorylation for sperm capacitation and other aspects of sperm function, we conclude that EBs may affect these events.
BorreliaSpirochetes Upregulate Release and Activation of Matrix Metalloproteinase Gelatinase B (MMP-9) and Collagenase 1 (MMP-1) in Human Cells
Authors: Gebbia Joseph A. , Coleman James L. , Benach Jorge L 
Published: July 2002

ABSTRACTBorrelia burgdorferi, the spirochetal agent of Lyme disease, stimulated human peripheral blood monocytes to release pro-matrix metalloproteinase-9 (gelatinase B; pro-MMP-9) and active matrix metalloproteinase-1 (collagenase-1; MMP-1). Human neutrophils also released pro-MMP-9 and a 130-kDa protein with gelatinolytic activity in response to liveB. burgdorferi. In addition, U937 cells and human keratinocyte cells were also stimulated to release pro-MMP-9 under the same conditions. However, human umbilical vein endothelial cells (HUVECs) released pro-MMP-9 and pro-MMP-2 in a constitutive manner and were not influenced by live spirochetes. MMPs produced by human monocytes also enhanced the penetration ofB. burgdorferithrough extracellular matrix component barriers in vitro. Plasmin stabilized on the surface of the Lyme disease spirochete was shown to activate pro-MMP-9 to its active form. This active form was also observed in the plasma of mice infected with a relapsing fever borrelia. These results suggest that borreliae can upregulate MMPs and possibly mediate an activation cascade initiated by plasmin bound to the microbial surface. MMPs may play a role in dissemination of the Lyme disease spirochete and in the pathogenesis ofBorreliainfection.
Identification of
Legionella pneumophila
Genes Important for Infection of Amoebas by Signature-Tagged Mutagenesis
Authors: Polesky Andrea H. , Ross Julianna T. D. , Falkow Stanley , Tompkins Lucy S. 
Published: July 2002

ABSTRACT

Legionella pneumophila
is a facultative intracellular gram-negative rod that causes pneumonia in humans. Free-living amoebas are thought to serve as a reservoir for
Legionella
infections. Signature-tagged mutagenesis was employed to identify
Legionella pneumophila
genes necessary for survival in the amoeba
Acanthamoeba castellanii
. Six mutant strains were defective in assays of invasion and intracellular growth. Four mutants also exhibited invasion and replication defects in
Hartmannella vermiformis
, an amoeba linked to hospital outbreaks of
Legionella
pneumonia. The six mutants also were tested in macrophages derived from peripheral blood mononuclear cells. Two mutants had intracellular replication defects, and two different strains entered cells less efficiently. Two transposon insertions were in known
L. pneumophila
genes,
lspK
and
aroB
. The other four were in novel genes. One gene has similarity to a cytochrome
c
-type biogenesis protein of
Pseudomonas fluorescens
. Another has similarity to a transcriptional activator regulating flagellar biosynthesis in
Vibrio cholera
. The third is similar to
traA
of
Rhizobium
sp. strain NGR234, which is involved in conjugal transfer of DNA. The fourth has no homology. By using survival in amoeba as a selection, we have isolated mutant strains with a range of phenotypes; and we have potentially identified new
L. pneumophila
virulence genes.
Polarized Entry of Uropathogenic Afa/Dr Diffusely AdheringEscherichia coliStrain IH11128 into Human Epithelial Cells: Evidence for α5β1Integrin Recognition and Subsequent Internalization through a Pathway Involving Caveolae and Dynamic Unstable Microtubules
Authors: Guignot Julie , Bernet-Camard Marie-Françoise , Poüs Christian , Plançon Laure , Le Bouguenec Chantal , Servin Alain L. 
Published: July 2002

ABSTRACTAfa/Dr diffusely adheringEscherichia colistrain IH11128 bacteria basolaterally entered polarized epithelial cells by a CD55- and CD66e-independent mechanism through interaction with the α5β1integrin and a pathway involving caveolae and dynamic microtubules (MTs). IH11128 invasion within HeLa cells was dramatically decreased after the cells were treated with the cholesterol-extracting drug methyl-β-cyclodextrin or the caveola-disrupting drug filipin. Disassembly of the dynamically unstable MT network by the compound 201-F resulted in a total abolition of IH11128 entry. In apically infected polarized fully differentiated Caco-2/TC7 cells, no IH11128 entry was observed. The entry of bacteria into apically IH11128-infected fully differentiated Caco-2/TC7 cells was greatly enhanced by treating cells with Ca2+-free medium supplemented with EGTA, a procedure that disrupts intercellular junctions and thus exposes the basolateral surface to bacteria. Basally infected fully differentiated polarized Caco-2/TC7 cells grown on inverted inserts mounted in chamber culture showed a highly significant level of intracellular IH11128 bacteria compared with cells subjected to the apical route of infection. No expression of CD55 and CD66e, the receptors for the Afa/Dr adhesins, was found at the basolateral domains of these cells. Consistent with the hypothesis that a cell-to-cell adhesion molecule acts as a receptor for polarized IH11128 entry, an antibody blockade using anti-α5β1integrin polyclonal antibody completely abolished bacterial entry. Experiments conducted with the laboratory strainE. coliK-12 EC901 carrying the recombinant plasmid pBJN406, which expresses Dr hemagglutinin, demonstrated that thedraoperon is involved in polarized entry of IH11128 bacteria. Examined as a function of cell differentiation, the number of internalized bacteria decreased dramatically beyond cell confluency. Surviving intracellular IH11128 bacteria residing intracellularly had no effect on the functional differentiation of Caco-2/TC7 cells.
The
Haemophilus influenzae
Hia Adhesin Is an Autotransporter Protein That Remains Uncleaved at the C Terminus and Fully Cell Associated
Authors: St. Geme Joseph W. , Cutter David 
Published: July 2002

ABSTRACT

Nontypeable
Haemophilus influenzae
is a gram-negative commensal organism that is commonly associated with localized respiratory tract disease. The pathogenesis of disease begins with colonization of the nasopharynx, a process that likely depends on bacterial adherence to respiratory epithelial cells. Hia is the major adhesin expressed by a subset of nontypeable
H. influenzae
strains and promotes efficient adherence to a variety of human epithelial cell lines. Based on previous work, Hia is transported to the surface of
Escherichia coli
transformants and is capable of mediating
E. coli
adherence without the assistance of other
H. influenzae
proteins. In the present study, we examined the mechanism of Hia secretion. PhoA fusions, deletional mutagenesis, and N-terminal amino acid sequencing established that the signal for Hia export from the cytoplasm resides in the first 49 amino acids, including a 24-amino-acid stretch with striking similarity to the N terminus of a number of proteins belonging to the autotransporter family. Immunoelectron microscopy demonstrated that the Hia internal region defined by amino acids 221 to 779 is exposed on the bacterial surface. Secondary-structure analysis predicted that the C terminus of Hia forms a β-barrel with a central hydrophilic channel, and site-specific mutagenesis and fusion protein analysis demonstrated that the C terminus targets Hia to the outer membrane and functions as an outer membrane translocator, analogous to observations with autotransporter proteins. In contrast to typical autotransporter proteins, Hia undergoes no cleavage between the internal and C-terminal domains and remains fully cell associated. Together, these results suggest that Hia is the prototype of an important subfamily of autotransporter proteins.
InvB Is a Type III Secretion Chaperone Specific for SspA
Authors: Bronstein Philip A. , Miao Edward A. , Miller Samuel I. 
Published: July 2002

ABSTRACT

A wide variety of gram-negative bacteria utilize a specialized apparatus called the type III secretion system (TTSS) to translocate virulence factors directly into the cytoplasm of eukaryotic cells. These translocated effectors contribute to the pathogen's ability to infect and replicate within plant and animal hosts. The amino terminus of effector proteins contains sequences that are necessary and sufficient for both secretion and translocation by TTSS. Portions of these sequences contain binding sites for type III chaperones, which facilitate efficient secretion and translocation of specific effectors through TTSS. In this study, we have utilized the yeast two-hybrid assay to identify protein-protein interactions between effector and chaperone proteins encoded within
Salmonella
pathogenicity island 1 (SPI-1). Several interactions were identified including a novel interaction between the effector protein, SspA (SipA), and a putative chaperone, InvB. InvB was demonstrated to bind to the amino terminus of SspA in the bacterial cytoplasm. Furthermore, InvB acts as a type III chaperone for the efficient secretion and translocation of SspA by SPI-1. InvB also permitted translocation of SspA through the SPI-2 TTSS, indicating that it is an important regulator in the recognition of SspA as a target of TTSS. Finally, it was determined that InvB does not alter the transcription of
sspA
but that its absence results in reduced SspA protein levels in
Salmonella enterica
serovar Typhimurium.
Identification and Characterization of the Nitrobenzene Catabolic Plasmids pNB1 and pNB2 in
Pseudomonas putida
HS12
Authors: Park Hee-Sung , Kim Hak-Sung 
Published: July 2002

ABSTRACT

Pseudomonas putida
HS12, which is able to grow on nitrobenzene, was found to carry two plasmids, pNB1 and pNB2. The activity assay experiments of wild-type HS12(pNB1 and pNB2), a spontaneous mutant HS121(pNB2), and a cured derivative HS124(pNB1) demonstrated that the catabolic genes coding for the nitrobenzene-degrading enzymes, designated
nbz
, are located on two plasmids, pNB1 and pNB2. The genes
nbzA
,
nbzC
,
nbzD
, and
nbzE
, encoding nitrobenzene nitroreductase, 2-aminophenol 1,6-dioxygenase, 2-aminomuconic 6-semialdehyde dehydrogenase, and 2-aminomuconate deaminase, respectively, are located on pNB1 (59.1 kb). Meanwhile, the
nbzB
gene encoding hydroxylaminobenzene mutase, a second-step enzyme in the nitrobenzene catabolic pathway, was found in pNB2 (43.8 kb). Physical mapping, cloning, and functional analysis of the two plasmids and their subclones in
Escherichia coli
strains revealed in more detail the genetic organization of the catabolic plasmids pNB1 and pNB2. The genes
nbzA
and
nbzB
are located on the 1.1-kb
Sma
I-
Sna
BI fragment of pNB1 and the 1.0-kb
Ssp
I-
Sph
I fragment of pNB2, respectively, and their expressions were not tightly regulated. On the other hand, the genes
nbzC
,
nbzD
, and
nbzE
, involved in the ring cleavage pathway of 2-aminophenol, are localized on the 6.6-kb
Sna
BI-
Sma
I fragment of pNB1 and clustered in the order
nbzC-nbzD-nbzE
as an operon. The
nbzCDE
genes, which are transcribed in the opposite direction of the
nbzA
gene, are coordinately regulated by both nitrobenzene and a positive transcriptional regulator that seems to be encoded on pNB2.
DsbA and DsbC Affect Extracellular Enzyme Formation in
Pseudomonas aeruginosa
Authors: Urban Andreas , Leipelt Martina , Eggert Thorsten , Jaeger Karl-Erich 
Published: July 2002

ABSTRACT

DsbA and DsbC proteins involved in the periplasmic formation of disulfide bonds in
Pseudomonas aeruginosa
were identified and shown to play an important role for the formation of extracellular enzymes. Mutants deficient in either
dsbA
or
dsbC
or both genes were constructed, and extracellular elastase, alkaline phosphatase, and lipase activities were determined. The
dsbA
mutant no longer produced these enzymes, whereas the lipase activity was doubled in the
dsbC
mutant. Also, extracellar lipase production was severely reduced in a
P. aeruginosa dsbA
mutant in which an inactive DsbA variant carrying the mutation C34S was expressed. Even when the lipase gene
lipA
was constitutively expressed in
trans
in a
lipA dsbA
double mutant, lipase activity in cell extracts and culture supernatants was still reduced to about 25%. Interestingly, the presence of dithiothreitol in the growth medium completely inhibited the formation of extracellular lipase whereas the addition of dithiothreitol to a cell-free culture supernatant did not affect lipase activity. We conclude that the correct formation of the disulfide bond catalyzed in vivo by DsbA is necessary to stabilize periplasmic lipase. Such a stabilization is the prerequisite for efficient secretion using the type II pathway.
Constitutive Expression of
Escherichia coli tat
Genes Indicates an Important Role for the Twin-Arginine Translocase during Aerobic and Anaerobic Growth
Authors: Jack Rachael L. , Sargent Frank , Berks Ben C. , Sawers Gary , Palmer Tracy 
Published: July 2002

ABSTRACT

The transcription start sites for the
tatABCD
and
tatE
loci, encoding components of the Tat (twin-arginine translocase) protein export pathway, have been identified. Expression studies indicate that the
tatABCD
and
tatE
transcription units are expressed constitutively. Translational fusion experiments suggest that TatA is synthesized at a much higher level than the other Tat proteins.
VibD and VibH Are Required for Late Steps in Vibriobactin Biosynthesis in
Vibrio cholerae
Authors: Wyckoff Elizabeth E. , Smith Stacey L. , Payne Shelley M. 
Published: July 2002

ABSTRACT

Vibrio cholerae
synthesizes the catechol siderophore vibriobactin. In this report, we present the complete map of a vibriobactin gene region containing two previously unreported vibriobactin biosynthetic genes.
vibD
encodes a phosphopantetheinyl transferase, and
vibH
encodes a novel nonribosomal peptide synthase. Both VibD and VibH are required for vibriobactin biosynthesis.
In Vivo Titration of Mitomycin C Action by Four
Escherichia coli
Genomic Regions on Multicopy Plasmids
Authors: Wei Yan , Vollmer Amy C. , LaRossa Robert A. 
Published: July 2002

ABSTRACT

Mitomycin C (MMC), a DNA-damaging agent, is a potent inducer of the bacterial SOS response; surprisingly, it has not been used to select resistant mutants from wild-type
Escherichia coli
. MMC resistance is caused by the presence of any of four distinct
E. coli
genes (
mdfA, gyrl, rob
, and
sdiA
) on high-copy-number vectors.
mdfA
encodes a membrane efflux pump whose overexpression results in broad-spectrum chemical resistance. The
gyrI
(also called
sbmC
) gene product inhibits DNA gyrase activity in vitro, while the
rob
protein appears to function in transcriptional activation of efflux pumps. SdiA is a transcriptional activator of
ftsQAZ
genes involved in cell division.
Using Disulfide Bond Engineering To Study Conformational Changes in the β′260-309 Coiled-Coil Region of
Escherichia coli
RNA Polymerase during σ
70
Binding
Authors: Anthony Larry C. , Dombkowski Alan A. , Burgess Richard R. 
Published: July 2002

ABSTRACT

RNA polymerase of
Escherichia coli
is the sole enzyme responsible for mRNA synthesis in the cell. Upon binding of a sigma factor, the holoenzyme can direct transcription from specific promoter sequences. We have previously defined a region of the β′ subunit (β′260-309, amino acids 260 to 309) which adopts a coiled-coil conformation shown to interact with σ
70
both in vitro and in vivo. However, it was not known if the coiled-coil conformation was maintained upon binding to σ
70
. In this work, we engineered a disulfide bond within β′240-309 that locks the β′ coiled-coil region in the coiled-coil conformation, and we show that this “locked” peptide is able to bind to σ
70
. We also show that the locked coiled-coil is capable of inducing a conformational change within σ
70
that allows recognition of the −10 nontemplate strand of DNA. This suggests that the coiled-coil does not adopt a new conformation upon binding σ
70
or upon recognition of the −10 nontemplate strand of DNA.
Construction and Characterization of a
cheA
Mutant of
Treponema denticola
Authors: Lux Renate , Sim Jee-Hyun , Tsai Jon P. , Shi Wenyuan 
Published: July 2002

ABSTRACT

The
Treponema denticola cheA
gene, encoding the central kinase of the general chemotaxis pathway, was analyzed for its role in chemotaxis and tissue penetration. The
cheA
gene was interrupted by insertion of an
ermF-ermAM
gene cassette. Reverse transcription-PCR confirmed that the other downstream chemotaxis genes within the same operon (
cheW
,
cheX
, and
cheY
) were still expressed in the
cheA
mutant strain. Lack of
cheA
resulted in decreased swarming on soft-agar swarm plates and failure to respond chemotactically to a mixture of nutrients. Behavioral analyses using video microscopy revealed that the
cheA
mutant exhibited coordinated cell movement. The cellular reversal frequency, however, was severely reduced, indicating that CheA in
T. denticola
mainly controls cellular reversal and that active chemotaxis signaling input is not required for coordination of flagellar rotation at both cell poles.
Multilocus Genotyping Indicates that the Ability To Invade the Bloodstream Is Widespread among
Candida albicans
Isolates
Authors: Luu Lien N. , Cowen Leah E. , Sirjusingh Caroline , Kohn Linda M. , Anderson James B. 
Published: July 2002

ABSTRACT

Multilocus genotyping was used to compare populations of
Candida albicans
from oral mucosa and blood. No significant differences in allele frequencies between the two samples were detected, and in a dendrogram of genotypic similarities, genotypes from both types of samples were finely interspersed. This is evidence for widespread distribution of invasive potential.