bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA Vaccination against Tuberculosis: Expression of a Ubiquitin-Conjugated Tuberculosis Protein Enhances Antimycobacterial Immunity
Authors: Delogu Giovanni , Howard Angela , Collins Frank M. , Morris Sheldon L. 
Published: July 2002

ABSTRACTGenetic immunization is a promising new technology for developing vaccines against tuberculosis that are more effective. In the present study, we evaluated the effects of intracellular turnover of antigens expressed by DNA vaccines on the immune response induced by these vaccines in a mouse model of pulmonary tuberculosis. The mycobacterial culture filtrate protein MPT64 was expressed as a chimeric protein fused to one of three variants of the ubiquitin protein (UbG, UbA, and UbGR) known to differentially affect the intracellular processing of the coexpressed antigens. Immunoblot analysis of cell lysates of in vitro-transfected cells showed substantial differences in the degradation rate of ubiquinated MPT64 (i.e., UbG64 < UbA64 < UbGR64). The specific immune response generated in mice correlated with the stability of the ubiquitin-conjugated antigen. The UbA64 DNA vaccine induced a weak humoral response compared to UbG64, and a mixed population of interleukin-4 (IL-4)- and gamma interferon (IFN-γ)-secreting cells. Vaccination with the UbGR64 plasmid generated a strong Th1 cell response (high IFN-γ, low IL-4) in the absence of a detectable humoral response. Aerogenic challenge of vaccinated mice withMycobacterium tuberculosisindicated that immunization with both the UbA64- and UbGR64-expressing plasmids evoked an enhanced protective response compared to the vector control. The expression of mycobacterial antigens from DNA vaccines as fusion proteins with a destabilizing ubiquitin molecule (UbA or UbGR) shifted the host response toward a stronger Th1-type immunity which was characterized by low specific antibody levels, high numbers of IFN-γ-secreting cells, and significant resistance to a tuberculous challenge.
Reduced Transendothelial Migration of Monocytes Infected byCoxiella burnetii
Authors: Dellacasagrande Jérôme , Moulin Pierre A. , Guilianelli Catherine , Capo Christian , Raoult Didier , Grau Georges E. , Mege Jean-Louis 
Published: July 2002

ABSTRACTThe migratory properties of THP1 monocytes infected byCoxiella burnetiiwere determined in a transmigration assay across a human microvascular endothelial cell monolayer. Transendothelial migration of monocytes infected by virulent, but not avirulent,C. burnetiiwas inhibited. This inhibition was observed in spite of conserved adherence properties of infected monocytes.
Escherichia coli
K1
aslA
Contributes to Invasion of Brain Microvascular Endothelial Cells In Vitro and In Vivo
Authors: Hoffman Jill A. , Badger Julie L. , Zhang Yan , Huang Sheng-He , Kim Kwang Sik 
Published: July 2002

ABSTRACT

Neonatal
Escherichia coli
meningitis remains a devastating disease, with unacceptably high morbidity and mortality despite advances in supportive care measures and bactericidal antibiotics. To further our ability to improve the outcome of affected neonates, a better understanding of the pathogenesis of the disease is necessary. To identify potential bacterial genes which contribute to
E. coli
invasion of the blood-brain barrier, a cerebrospinal fluid isolate of
E. coli
K1 was mutagenized with Tn
phoA
. Tn
phoA
mutant 27A-6 was found to have a significantly decreased ability to invade brain microvascular endothelial cells compared to the wild type. In vivo, 32% of the animals infected with mutant 27A-6 developed meningitis, compared to 82% of those infected with the parent strain, despite similar levels of bacteremia. The DNA flanking the Tn
phoA
insertion in 27A-6 was cloned and sequenced and determined to be homologous to
E. coli
K-12
aslA
(arylsulfatase-like gene). The deduced amino acid sequence of the
E. coli
K1
aslA
gene product shows homology to a well-characterized arylsulfatase family of enzymes found in eukaryotes, as well as prokaryotes. Two additional
aslA
mutants were constructed by targeted gene disruption and internal gene deletion. Both of these mutants demonstrated decreased invasion phenotypes, similar to that of Tn
phoA
mutant 27A-6. Complementation of the decreased-invasion phenotypes of these mutants was achieved when
aslA
was supplied in
trans
. This is the first demonstration that this locus contributes to invasion of the blood-brain barrier by
E. coli
K1.
Role of Inducible Nitric Oxide Synthase in Resistance toMycobacterium lepraein Mice
Authors: Adams Linda B. , Job Charles K. , Krahenbuhl James L. 
Published: July 2002

ABSTRACTThe manifestation of leprosy in humans is largely determined by host immunity toMycobacterium lepraeand is a model for immunoregulation in a human disease. However, animal models available for exploration of the leprosy spectrum are inadequate. This study exploredM. lepraeinfection in mice deficient in inducible nitric oxide synthase, and this report describes elements resembling borderline tuberculoid leprosy in humans.
Biochemical and Biological Characterization of the ProtectiveLeishmania pifanoiAmastigote Antigen P-8
Authors: Colmenares M. , Tiemeyer M. , Kima P. , McMahon-Pratt D. 
Published: July 2002

ABSTRACTTheLeishmania pifanoiamastigote antigen P-8 has been previously shown to induce protective immunity in a murine model of cutaneous leishmaniasis (L. Soong, S. M. Duboise, P. Kima, and D. McMahon-Pratt, Infect. Immun. 63:3559–3566, 1995). As this antigen is of interest for further vaccine studies, the biochemical characterization of P-8 was undertaken. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western-blot analysis, and gel filtration chromatography revealed that P-8 antigen consisted of two proteoglycolipid complexes. The P-8 epitope is associated with theL. pifanoiamastigote-specific glycolipid components found in the two complexes. The P-8 complex 1 (P-8c1) consists of a 56-kDa serine metalloproteinase, apolipoprotein E (derived from fetal bovine serum), and amastigote-specific glycolipids. The P-8 complex 2 (P-8c2) consists of a 31-kDa cysteine proteinase associated with amastigote glycolipids. Biochemical analyses suggest that the P-8 antigenic glycolipids may be distinct from previously describedLeishmaniaglycolipids (glycosylinositolphospholipids and sphingoglycolipids). Protective immunity studies revealed that P-8c1 (serine metalloproteinase-glycolipid complex) confers comparable protection against infection as immunopurified P-8. The isolated P-8c2 (cysteine proteinase-glycolipid complex) does not provide significant protection, nor does stimulation with P-8c2 result in significant T-cell activation in P-8- or P-8c2-vaccinated mice. Consequently, the P-8c1 complex appears to be the immunodominant component of P-8.
Mycobacterium ulceransCytotoxicity in an Adipose Cell Model
Authors: Dobos Karen M. , Small Pamela L. , Deslauriers Manon , Quinn Fredrick D. , King C. Harold 
Published: July 2002

ABSTRACTAn adipose cell (SW872) model was developed to observe cellular necrosis and apoptosis uponMycobacterium ulceransinfection and treatment with mycobacterial exudate. Apoptosis was likely due to secreted proteins, while necrosis was likely due to mycolactone. Our data suggest that additional factors inM.ulceransmay be involved in Buruli ulcer pathogenesis.
Characterization of an Intestinal Epithelial Cell Receptor Recognized by theCryptosporidium parvumSporozoite Ligand CSL
Authors: Langer Rebecca C. , Schaefer Deborah A. , Riggs Michael W. 
Published: July 2002

ABSTRACTThe protozoan parasiteCryptosporidium parvumis a leading cause of diarrhea in humans and neonatal calves. The absence of approved parasite-specific drugs, vaccines, and immunotherapies for cryptosporidiosis relates in part to limited knowledge on the pathogenesis of zoite attachment and invasion. We recently reported that theC. parvumapical complex glycoprotein CSL contains a zoite ligand for intestinal epithelial cells which is defined by monoclonal antibody (MAb) 3E2. In the present study, the host cell receptor for CSL was characterized. For these studies, a panel of epithelial and mesenchymal cell lines was examined for permissiveness toC. parvumand the ability to bind CSL. Cells of epithelial origin were significantly more permissive and bound significantly greater quantities of CSL than cells of mesenchymal origin. Caco-2 intestinal cells were selected from the epithelial panel for further characterization of the CSL receptor. Immunoelectron microscopy demonstrated that CSL bound initially to the surface of Caco-2 cells and was rapidly internalized. The molecule bound by CSL was identified as an 85-kDa Caco-2 cell surface protein by radioimmunoprecipitation and CSL affinity chromatography. Sporozoite incubation with the isolated 85-kDa protein reduced binding of MAb 3E2. Further, attachment and invasion were significantly inhibited when sporozoites were incubated with the 85-kDa protein prior to inoculation onto Caco-2 cells. These observations indicate that the 85-kDa protein functions as a Caco-2 cell receptor for CSL. CSL also bound specifically to intestinal epithelium from calves, indicating receptor expression in a second important host species. Molecular characterization of the CSL receptor may lead to novel avenues for disrupting ligand-receptor interactions in the pathogenesis ofC. parvuminfection.
Effect of Mycobacterial Phospholipids on Interaction ofMycobacterium tuberculosiswith Macrophages
Authors: Thorson Lisa M. , Doxsee Daniel , Scott Monisha G. , Wheeler Paul , Stokes Richard W. 
Published: July 2002

ABSTRACTThis study demonstrates that pretreatment of macrophages with phosphatidylinositol, of either soya bean or mycobacterial origin, results in a down-regulation of the binding and uptake ofMycobacterium tuberculosisby the phagocytes. We also describe the novel observation that cardiolipin induces an increase in the binding and uptake ofM. tuberculosisby macrophages. Neither phospholipid interacts with macrophages via the 2F8 epitope of scavenger receptor A, and treatment of macrophages with either phospholipid results in a down-regulation of CR3 function and tumor necrosis factor alpha production by the phagocyte. We have also shown that the ability of macrophages to interact with mycobacteria is greatly affected by an as yet unidentified product from the interaction of chloroform and polypropylene tubes.
Subcytocidal Attack by Staphylococcal Alpha-Toxin Activates NF-κB and Induces Interleukin-8 Production
Authors: Dragneva Y. , Anuradha C. D. , Valeva A. , Hoffmann A. , Bhakdi S. , Husmann M. 
Published: July 2002

ABSTRACTFormation of transmembrane pores by staphylococcal alpha-toxin can provoke a spectrum of events depending on target cell species and toxin dose, and in certain cases, repair of the lesions has been observed. Here, we report that transcriptional processes are activated as a response of cells to low toxin doses. Exposure of monocytic (THP-1) or epithelial (ECV304) cells to 40 to 160 ng/ml alpha-toxin provoked a drop in cellular ATP level that was followed by secretion of substantial amounts of interleukin-8 (IL-8). Cells transfected with constructs comprising the proximal IL-8 promoter fused to luciferase or to green fluorescent protein cDNA exhibited enhanced reporter gene expression following toxin treatment. Electrophoretic mobility shift and immunofluorescence assays demonstrated that IL-8 secretion was preceded by activation of NF-κB. Transfection experiments conducted with p65/p50 double-deficient cells showed that activation of the IL-8 promoter/reporter by toxin was absolutely dependent on NF-κB. In contrast, this transcription factor was not required for lesion repair. Attack of cells by low doses of a pore-forming toxin can lead to transcriptional gene activation, which is followed by production of mediators that may contribute to the initiation and propagation of inflammatory lesions.
CD8+T Cells Have an Essential Role in Pulmonary Clearance of NontypeableHaemophilus influenzaefollowing Mucosal Immunization
Authors: Foxwell A. Ruth , Kyd Jennelle M. , Karupiah Guna , Cripps Allan W. 
Published: July 2002

ABSTRACTA rodent respiratory experimental model has proved useful for investigating the immune mechanisms responsible for clearance of bacteria from the lungs. Immunohistochemical studies in immune and nonimmune rats have identified the cellular kinetics of response to bacterial pulmonary infection for CD8+, CD4+, and γδ+T cells; B cells; and the expression of major histocompatibility complex class II (MHC-II). During the course of bacterial clearance, there was no apparent proliferation or extravasation of lymphocytes, nor was there increased expression of MHC-II in nonimmune animals despite an influx of polymorphonuclear leukocytes, whereas in immunized animals there was an early influx of CD8+and γδ+T cells, followed by enhanced expression of the MHC-II marker, cellular infiltration by polymorphonuclear leukocytes, and finally an increased number of CD4+T cells. Depletion of CD8+T cells confirmed their vital contribution in the preprimed immune response to pulmonary infection by significantly decreasing the animals' ability to clear bacteria following challenge.
Regulation of OspE-Related, OspF-Related, and Elp Lipoproteins of
Borrelia burgdorferi
Strain 297 by Mammalian Host-Specific Signals
Authors: Hefty P. Scott , Jolliff Sarah E. , Caimano Melissa J. , Wikel Stephen K. , Radolf Justin D. , Akins Darrin R. 
Published: July 2002

ABSTRACT

In previous studies we have characterized the cp32/18 loci in
Borrelia burgdorferi
297 which encode OspE and OspF orthologs and a third group of lipoproteins which possess OspE/F-like leader peptides (Elps). To further these studies, we have comprehensively analyzed their patterns of expression throughout the borrelial enzootic cycle. Serial dilution reverse transcription-PCR analysis indicated that although a shift in temperature from 23 to 37°C induced transcription for all nine genes analyzed, this effect was often markedly enhanced in mammalian host-adapted organisms cultivated within dialysis membrane chambers (DMCs) implanted within the peritoneal cavities of rats. Indirect immunofluorescence assays performed on temperature-shifted, in vitro-cultivated spirochetes and organisms in the midguts of unfed and fed ticks revealed distinct expression profiles for many of the OspE-related, OspF-related, and Elp proteins. Other than BbK2.10 and ElpA1, all were expressed by temperature-shifted organisms, while only OspE, ElpB1, OspF, and BbK2.11 were expressed in the midguts of fed ticks. Additionally, although mRNA was detected for all nine lipoprotein-encoding genes, two of these proteins (BbK2.10 and ElpA1) were not expressed by spirochetes cultivated in vitro, within DMCs, or by spirochetes within tick midguts. However, the observation that
B. burgdorferi
-infected mice generated specific antibodies against BbK2.10 and ElpA1 indicated that these antigens are expressed only in the mammalian host and that a form of posttranscriptional regulation is involved. Analysis of the upstream regions of these genes revealed several differences between their promoter regions, the majority of which were found in the −10 and −35 hexamers and the spacer regions between them. Also, rather than undergoing simultaneous upregulation during tick feeding, these genes and the corresponding lipoproteins appear to be subject to progressive recruitment or enhancement of expression as
B. burgdorferi
is transmitted from its tick vector to the mammalian host. These findings underscore the potential relevance of these molecules to the pathogenic events of early Lyme disease.
Endogenous Interleukin-10 Is Required for Prevention of a Hyperinflammatory Intracerebral Immune Response inListeria monocytogenesMeningoencephalitis
Authors: Deckert Martina , Soltek Sabine , Geginat Gernot , Lütjen Sonja , Montesinos-Rongen Manuel , Hof Herbert , Schlüter Dirk 
Published: July 2002

ABSTRACTTo analyze the role of interleukin-10 (IL-10) in bacterial cerebral infections, we studied cerebral listeriosis in IL-10-deficient (IL-10−/−) and wild-type (WT) mice, the latter of which express high levels of IL-10 in both primary and secondary cerebral listeriosis. IL-10−/−mice succumbed to primary as well as secondary listeriosis, whereas WT mice were significantly protected from secondary listeriosis by prior intraperitoneal immunization withListeria monocytogenes. Meningoencephalitis developed in both strains; however, in IL-10−/−mice the inflammation was more severe and associated with increased brain edema and multiple intracerebral hemorrhages. IL-10−/−mice recruited significantly increased numbers of leukocytes, in particular granulocytes, to the brain, and the intracerebral cytokine (tumor necrosis factor, IL-1, IL-12, gamma interferon, and inducible nitric oxide synthase) and chemokine (crg2/IP-10, RANTES, MuMig, macrophage inflammatory protein 1α [MIP-1α], and MIP-1β) transcription was enhanced compared to that in WT mice. Despite this prominent hyperinflammation, the frequencies of intracerebralL. monocytogenes-specific CD8+T cells were reduced and the intracerebral bacterial load was not reduced in IL-10−/−mice compared to WT mice. Following intraperitoneal infection, IL-10−/−mice exhibited hepatic hyperinflammation without better bacterial clearance; however, in contrast to the mice with cerebral listeriosis, they did not succumb, illustrating that intrinsic factors of the target organ have a strong impact on the course and outcome of the infection.
Proteolytic Inhibition ofSalmonella entericaSerovar Typhimurium-Induced Activation of the Mitogen-Activated Protein Kinases ERK and JNK in Cultured Human Intestinal Cells
Authors: Mynott Tracey L. , Crossett Ben , Prathalingam S. Radhika 
Published: July 2002

ABSTRACTBromelain, a mixture of cysteine proteases from pineapple stems, blocks signaling by the mitogen-activated protein (MAP) kinases extracellular regulated kinase 1 (ERK-1) and ERK-2, inhibits inflammation, and protects against enterotoxigenicEscherichia coliinfection. In this study, we examined the effect of bromelain onSalmonella entericaserovar Typhimurium infection, since an important feature of its pathogenesis is its ability to induce activation of ERK-1 and ERK-2, which leads to internalization of bacteria and induction of inflammatory responses. Our results show that bromelain dose dependently blocks serovar Typhimurium-induced ERK-1, ERK-2, and c-Jun NH2-terminal kinase (JNK) activation in Caco-2 cells. Bromelain also blocked signaling induced by carbachol and anisomycin, pharmacological MAP kinase agonists. Despite bromelain inhibition of serovar Typhimurium-induced MAP kinase signaling, it did not prevent subsequent invasion of the Caco-2 cells by serovar Typhimurium or alter serovar Typhimurium -induced decreases in resistance across Caco-2 monolayers. Surprisingly, bromelain also did not block serovar Typhimurium-induced interleukin-8 (IL-8) secretion but synergized with serovar Typhimurium to enhance IL-8 production. We also found that serovar Typhimurium does not induce ERK phosphorylation in Caco-2 cells in the absence of serum but that serovar Typhimurium-induced invasion and decreases in monolayer resistance are unaffected. Collectively, these data indicate that serovar Typhimurium-induced invasion of Caco-2 cells, changes in the resistance of epithelial cell monolayers, and IL-8 production can occur independently of the ERK and JNK signaling pathways. Data also confirm that bromelain is a novel inhibitor of MAP kinase signaling pathways and suggest a novel role for proteases as inhibitors of signal transduction pathways in intestinal epithelial cells.
Listeria monocytogenesInfection in Caspase-11-Deficient Mice
Authors: Mueller Nicolas J. , Wilkinson Robert A. , Fishman Jay A. 
Published: July 2002

ABSTRACTCaspase-11 (Cas11) is a cysteine protease involved in programmed cell death and cytokine maturation. Through activation of Cas1 (interleukin-1β [IL-1β]-converting enzyme), Cas11 is directly involved in the maturation of IL-1β and IL-18. Apoptosis is mediated through Cas3. Given the role of apoptosis and cytokine signaling during the innate immune response in intracellular infection, we examined Cas11-deficient (Cas11−/−) mice during infection withListeria monocytogenes. Cas11−/−and wild-type C57BL/6 mice were equally susceptible to intravenous infection withL. monocytogenes, resulting in similar bacterial burdens in tissue and similar survival rates. By contrast, enhanced susceptibility was observed in control mice on a mixed genetic 129/C57BL/DBA2 background. Cas11−/−and wild-type mice infected withListeriahad similar hepatic microabscess formation in terms of histologic appearance, size, and number. Apoptosis ofL. monocytogenes-infected hepatocytes in vivo and in vitro in primary culture was not altered by the absence of Cas11. Serum IL-18 and IL-1β levels were similar in Cas11−/−mice and controls. Endotoxin (lipopolysaccharide [LPS])-challenged Cas11−/−mice were deficient in the production of gamma interferon. IL-1β responses in Cas11−/−were normal with intravenous administration of LPS but decreased with intraperitoneal administration. Our findings suggest that Cas11 deficiency does not impair the immune response to infection withL. monocytogenes. Apoptosis and maturation of IL-18 and IL-1β were normal despite Cas11 deficiency. LPS-induced proinflammatory pathways are altered by the absence of Cas11. While Cas11-mediated Cas1 and Cas3 activation is crucial for cytokine maturation and apoptosis during inflammation, alternative pathways allow normal inflammatory and apoptotic responses during infection withL. monocytogenes.
Inhibition of Fusion ofChlamydia trachomatisInclusions at 32°C Correlates with Restricted Export of IncA
Authors: Fields K. A. , Fischer E. , Hackstadt T. 
Published: July 2002

ABSTRACTChlamydia trachomatisis an obligate intracellular bacterium that develops within a parasitophorous vacuole termed an inclusion. The inclusion is nonfusogenic with lysosomes but intercepts lipids from a host cell exocytic pathway. Initiation of chlamydial development is concurrent with modification of the inclusion membrane by a set ofC. trachomatis-encoded proteins collectively designated Incs. One of these Incs, IncA, is functionally associated with the homotypic fusion of inclusions. Inclusions also do not fuse when cultures are multiply infected withC. trachomatisand cultivated at 32°C. We obtained evidence linking these experimental observations by characterizing IncA localization in 32°C cultures. Analysis of inclusions by light and transmission electron microscopy confirmed that HeLa cells infected with multipleC. trachomatiselementary bodies and cultivated at 32°C for 24 h contained multiple, independent inclusions. Reverse transcriptase PCR and immunoblot analyses ofC. trachomatis-infected HeLa cells demonstrated the presence of IncA at 24 h in 32°C cultures. When parallel cultures were probed with IncA-specific antibodies in indirect immunofluorescence assays, IncA was detectable in intracellular chlamydiae but not within the inclusion membrane. In addition, analysis of purified reticulate bodies from 37 and 32°C cultures showed that bacterium-associated pools of IncA are enriched in cultures grown at 32°C. Microscopic observation of infected cells revealed that some vacuoles had fused by 48 h postinfection, and this finding was correlated with the detection of IncA in inclusion membranes by immunofluorescence microscopy. The data are consistent with a requirement for IncA in fusions ofC. trachomatisinclusions and suggest that the effect of incubation at 32°C is manifested by restricted export of IncA to the inclusion membrane.