bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-Term Effect of Heat Shock Protein 60 from
Actinobacillus actinomycetemcomitans
on Epithelial Cell Viability and Mitogen-Activated Protein Kinases
Authors: Zhang Liangxuan , Pelech Steven , Uitto Veli-Jukka 
Published: December 2003

ABSTRACT

Our previous studies showed that bacterial heat shock protein 60 (hsp60) induces cultured epithelial cell proliferation within 24 h. Here we investigated the long-term effects of heat shock protein 60 isolated from
Actinobacillus actinomycetemcomitans
on skin keratinocyte (HaCaT cell line) viability and the cell signaling involved. Prolonged incubation in the presence of hsp60 increased the rate of epithelial cell death. The number of viable cells in hsp60-treated culture was 37% higher than the number in the control at 24 h but 27% lower at 144 h. A kinetics study of the effect of hsp60 on the phosphorylation of mitogen-activated protein kinases (MAPKs) involving Western blotting with phospho-specific antibodies showed that in addition to a transient early increase in p38 levels, a second peak appeared in keratinocytes 24 h after the addition of hsp60. In contrast, prolonged incubation with hsp60 caused a decrease in the level of phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) compared with that in the controls, possibly as a result of protein phosphatase activity. We found that hsp60 increased the levels of several phosphatases, including MAP-2, which strongly dephosphorylates ERK1/2. Moreover, hsp60 increased the level of tumor necrosis factor alpha (TNF-α) in culture medium in a dose-dependent manner. TNF-α added to culture showed a cytotoxic effect on epithelial cells, particularly with longer incubation periods. TNF-α also induced the phosphorylation of p38. Finally, our results show that bacterial hsp60 inhibited stress-induced synthesis of cellular hsp60. Therefore, several cell behavior changes caused by long-term exposure to bacterial hsp60 may lead to impaired epithelial cell viability.
Immune Responses to Mycobacterial Antigens in the Gambian Population: Implications for Vaccines and Immunodiagnostic Test Design
Authors: Vekemans Johan , Ota Martin O. C. , Sillah Jackson , Fielding Katherine , Alderson Mark R. , Skeiky Yasir A. W. , Dalemans Wilfried , McAdam Keith P. W. J. , Lienhardt Christian , Marchant Arnaud 
Published: December 2003

ABSTRACTRecombinant immunodominant mycobacterial antigens are needed for the development of new vaccines and immunodiagnostic tools for use against tuberculosis. Ubiquitous exposure to mycobacteria in tropical countries could influence vaccine-induced immunity and the specificity of tuberculosis immunodiagnosis. For this study conducted in The Gambia, cellular immune responses to recombinant mycobacterial antigens were characterized inMycobacterium bovisBCG-vaccinated and nonvaccinated infants, adult community controls, household contacts, health care workers, and tuberculosis patients. Neonatal BCG vaccination induced gamma interferon (IFN-γ) responses to Mtb8.4, Mtb32-C, Mtb39A, Mtb9.9A, and Mtb32-N, but not CFP-10 (Mtb11) and α-crystallin (Mtb16). Exposure toMycobacterium tuberculosisin household contacts and health care workers was associated with high responses to CFP-10 and α-crystallin. Generally, low IFN-γ responses were found in tuberculosis patients. These results suggest that Mtb8.4, Mtb32-C, Mtb39A, Mtb9.9A, and Mtb32-N may be used in a subunit vaccine to boost BCG-induced immunity. While CFP-10 and α-crystallin are promising candidates for the immunodiagnosis ofM. tuberculosisinfection or for vaccine use, disease-associated immunosuppression may prevent IFN-γ immunodiagnosis of more advanced tuberculosis.
Induction of Interleukin-8 in T84 Cells byVibrio cholerae
Authors: Zhou Xin , Gao Da Q. , Michalski Jane , Benitez Jorge A. , Kaper James B. 
Published: December 2003

ABSTRACTThe induction of interleukin-8 (IL-8) in vitro has been suggested to correlate with the reactogenicity ofVibrio choleraevaccine candidates.V. choleraevaccine candidate 638, a hemagglutinin protease/hap-defective strain, was recently reported to be well tolerated in human volunteers, suggesting a role for Hap in reactogenicity. We examined the role ofhapin the induction of IL-8 in intestinal epithelial T84 cells. Wild-typeV. choleraestrains 3038 and C7258 and a vaccine candidate strain, JBK70, induced levels of IL-8 similar to those of their isogenichapmutants. Supernatant containing Hap did not stimulate IL-8 production at a variety of concentrations tested, suggesting that Hap itself does not induce IL-8 production. Furthermore, supernatant from CVD115, which had deletions ofhapandrtxA(encoding repeats in toxin) and was derived from a reactogenic strain, CVD110, induced IL-8 production in T84 cells in a dose-dependent manner. The IL-8-stimulating activity of CVD115 culture supernatants was growth phase dependent and was strongest in stationary phase cultures. This IL-8 stimulator(s) was resistant to heat treatment but sensitive to proteinase. Protease activity in vitro did not correlate with the reactogenicity ofV. choleraevaccine candidates. Our data suggest that Hap is not an IL-8 inducer in T84 cells and that the IL-8 stimulator in the supernatant ofV. choleraeculture may play a role in reactogenicity.
Both Free-Living and Parasitic Nematodes Induce a Characteristic Th2 Response That Is Dependent on the Presence of Intact Glycans
Authors: Tawill Salah , Le Goff Laetitia , Ali Fahimeda , Blaxter Mark , Allen Judith E. 
Published: December 2003

ABSTRACTInfection with parasitic nematodes is characterized by the induction of a profound type 2 immune response. We have studied the role of glycans in the induction of the skewed type 2 response by antigens of the parasitic nematodeBrugia malayias well as the free-living nematodeCaenorhabditis elegans. Lymph node cells from BALB/c mice immunized with soluble extracts of the two nematodes showed distinct antigen-specific proliferation and cytokine production; however, both nematodes induced antigen-specific interleukin 4 (IL-4) production, demonstrating that the induction of a biased type 2 response is not unique to parasitic nematodes. Sodium periodate-treated soluble extracts of both nematodes consistently induced significantly less IL-4 production than the respective mock-treated extracts, indicating that glycans play a critical role in the induction of the Th2 immune response by these nematodes. The glycan-dependent induction of the Th2-potentiating cytokine IL-4 occurs by 72 h postinoculation. Our data suggest that glycan determinants common to nematodes act as ligands, displaying distinct molecular patterns that trigger the immune system to launch a biased Th2 immune response upon exposure to these organisms or their products. Further, the similarity of our findings to those forSchistosoma mansoniegg antigen is striking considering the enormous phylogenetic distance between nematodes and trematodes. These data thus have important implications for how the mammalian host responds to widely divergent metazoan invaders and suggest that the powerfulC. elegansmodel system can be used to address these questions.
Contribution of Glutathione Peroxidase to the Virulence of
Streptococcus pyogenes
Authors: Brenot Audrey , King Katherine Y. , Janowiak Blythe , Griffith Owen , Caparon Michael G. 
Published: December 2003

ABSTRACT

Glutathione peroxidases are widespread among eukaryotic organisms and function as a major defense against hydrogen peroxide and organic peroxides. However, glutathione peroxidases are not well studied among prokaryotic organisms and have not previously been shown to promote bacterial virulence. Recently, a gene with homology to glutathione peroxidase was shown to contribute to the antioxidant defenses of
Streptococcus pyogenes
(group A streptococcus). Since this bacterium causes numerous suppurative diseases that require it to thrive in highly inflamed tissue, it was of interest to determine if glutathione peroxidase is important for virulence. In this study, we report that GpoA glutathione peroxidase is the major glutathione peroxidase in
S. pyogenes
and is essential for
S. pyogenes
pathogenesis in several murine models that mimic different aspects of streptococcal suppurative disease. In contrast, glutathione peroxidase is not essential for virulence in a zebrafish model of streptococcal myositis, a disease characterized by the absence of an inflammatory cell infiltrate. Taken together, these data suggest that
S. pyogenes
requires glutathione peroxidase to adapt to oxidative stress that accompanies an inflammatory response, and the data provide the first demonstration of a role for glutathione peroxidase in bacterial virulence. The fact that genes encoding putative glutathione peroxidases are found in the genomes of many pathogenic bacterial species suggests that glutathione peroxidase may have a general role in bacterial pathogenesis.
GeneExpression in HL60 Granulocytoids and Human PolymorphonuclearLeukocytes Exposed toCandidaalbicans†
Authors: Mullick Alaka , Elias Miria , Harakidas Penelope , Marcil Anne , Whiteway Malcolm , Ge Bing , Hudson Thomas J. , Caron Antoine W. , Bourget Lucie , Picard Serge , Jovcevski Orce , Massie Bernard , Thomas David Y. 
Published: December 2003

ABSTRACTCandida albicansis an opportunistic human pathogen causing both superficial and disseminated diseases. It is a dimorphic fungus, switching between yeast and hyphal forms, depending on cues from its microenvironment. Hyphae play an important role in the pathogenesis of candidiasis. The host's response toCandidainfection is multifaceted and includes the participation of granulocytes as key effector cells. The aim of this investigation was to study host gene expression during granulocyte-Candidainteraction. Effector cells were generated by the granulocytic differentiation of HL60 cells. The resulting cell population was shown to be morphologically and functionally equivalent to granulocytes and is therefore referred to as HL60 granulocytoids for the purposes of this study. Gene expression profiles were determined 1 h after hosts were infected withC. albicans.ThreeCandida-granulocytoid ratios were chosen to reflect different degrees of HL60 granulocytoid inhibition ofC. albicans. The data demonstrate that at the high pathogen-host ratio,C. albicansmodulated the HL60 granulocytoid's response by downregulating the expression of known antimicrobial genes. In addition, looking at the expression of a large number of genes, not all of which have necessarily been implicated in candidastatic or candidacidal mechanisms, it has been possible to describe the physiological response of the HL60 granulocytoid to an infectious challenge withC. albicans. Finally, some of the observed changes in HL60 granulocytoid gene expression were investigated in freshly isolated human polymorphonuclear leukocytes infected withC. albicans. Similar changes were seen in these primary human cells, lending support to the validity of this model.
Anthrax Lethal Toxin Induces Human Endothelial Cell Apoptosis
Authors: Kirby James E. 
Published: December 2003

ABSTRACT

Because of its ease of dispersal and high lethality,
Bacillus anthracis
is one of the most feared biowarfare agents. A better understanding of anthrax pathogenesis is urgently needed to develop new therapies for systemic disease that is relatively unresponsive to antibiotics. Although experimental evidence has implicated a role for macrophages in anthrax pathogenesis, clinical and pathological observations suggest that a direct insult to the host vasculature may also be important. Two bacterial toxins, lethal toxin and edema toxin, are believed to mediate the clinical sequelae of anthrax. Here, I examined whether these toxins are directly toxic to endothelial cells, the cell type that lines the interior of blood vessels. I show for the first time that lethal toxin but not edema toxin reduces the viability of cultured human endothelial cells and induces caspase-dependent endothelial apoptosis. In addition, this toxicity affects both microvascular and large vessel endothelial cells as well as endothelial cells that have differentiated into tubules within a type I collagen extracellular matrix. Finally, lethal toxin induces cleavage of mitogen-activated protein kinase kinases in endothelial cells and inhibits phosphorylation of ERK, p38, and JNK p46. Based on the contributions of these pathways to endothelial survival, I propose that lethal toxin-mediated cytotoxicity/apoptosis results primarily through inhibition of the ERK pathway. I also hypothesize that the observed endothelial toxicity contributes to vascular pathology and hemorrhage during systemic anthrax.
Brucella abortusRough Mutants Are Cytopathic for Macrophages in Culture
Authors: Pei Jianwu , Ficht Thomas A. 
Published: December 2003

ABSTRACTRough mutants ofBrucellaspp. are attenuated for survival in animal models. However, conflicting in vitro evidence has been obtained concerning the intracellular survival of rough mutants. Transposon-derived rough mutants isolated in our laboratory were previously shown to exhibit small but significant reductions in intracellular survival in a 12-h in vitro assay. Several recent publications report that rough mutants exhibited increased macrophage uptake relative to their smooth parental strains, and a reduction in numbers at the end of the assay has been interpreted as intracellular killing. In an effort to explore the role of O antigen in the interaction betweenBrucella abortusand macrophages, we have monitored the uptake of rough mutants and survival in vitro by using the murine macrophage cell line J774.A1. The results confirm a 10- to 20-fold-increased uptake of rough mutants over that of smooth organisms under standard conditions. Recovery of the rough mutants persisted up to 8 h postinfection, but at the point when intracellular replication of the smooth organisms was observed, the number of rough organisms recovered declined. Fluorescence microscopy revealed the intracellular multiplication of both smooth and rough organisms, and assays performed in the absence of antibiotic confirmed the replication of the rough organisms. Examination by phase-contrast microscopy revealed the lytic death of macrophages infected with the rough mutants, which was confirmed by the release of lactate dehydrogenase (LDH) from the cell cytoplasm. Thus, the decline in the number of rough organisms was the result of the lysis of macrophages and not from intracellular killing. The cytopathic effect is characterized as necrotic rather than apoptotic cell death based on early LDH release, annexin V and propidium iodide staining, morphological changes of infected cells and nuclei, and glycine protection. The cytopathic effect was observed with macrophages at multiplicities of infection (MOIs) of as low as 20 and was not observed with epithelial cells at MOIs of as high as 2000. These findings suggest a role for O antigen during the early stages of host-agent interaction that is essential in establishing an intracellular niche that maintains and supports persistent intracellular infection resulting in disease.
Chlamydia-Infected Cells Continue To Undergo Mitosis and Resist Induction of Apoptosis
Authors: Greene Whitney , Xiao Yangming , Huang Yanqing , McClarty Grant , Zhong Guangming 
Published: December 2003

ABSTRACTBoth anti- and proapoptotic activities have been reported to occur during chlamydial infection. To reconcile the apparent controversy, we compared host cell apoptotic responses to infection with 17 different chlamydial serovars and strains. None of the serovars caused any biologically significant apoptosis in the infected host cells. Host cells in chlamydia-infected cultures can continue to undergo DNA synthesis and mitosis. Chlamydia-infected cells are resistant to apoptosis induction, although the extent of the antiapoptotic ability varied between serovars. These observations have demonstrated that an anti- but not proapoptotic activity is the prevailing event in chlamydia-infected cultures.
Immunotherapy ofTrypanosoma cruziInfection with DNA Vaccines in Mice
Authors: Dumonteil Eric , Escobedo-Ortegon Javier , Reyes-Rodriguez Norma , Arjona-Torres Arletty , Ramirez-Sierra Maria Jesus 
Published: December 2003

ABSTRACTThe mechanisms involved in the pathology of chronic chagasic cardiomyopathy are still debated, and the controversy has interfered with the development of new treatments and vaccines. Because of the potential of DNA vaccines for immunotherapy of chronic and infectious diseases, we tested if DNA vaccines could control an ongoingTrypanosoma cruziinfection. BALB/c mice were infected with a lethal dose (5 × 104parasites) as a model of acute infection, and then they were treated with two injections of 100 μg of plasmid DNA 1 week apart, beginning on day 5 postinfection. Control mice had high levels of parasitemia and mortality and severe cardiac inflammation, while mice treated with plasmid DNA encoding trypomastigote surface antigen 1 or Tc24 had reduced parasitemia and mild cardiac inflammation and >70% survived the infection. The efficacy of the immunotherapy also was significant when it was delayed until days 10 and 15 after infection. Parasitological analysis of cardiac tissue of surviving mice indicated that most mice still contained detectable parasite kinetoplast DNA but fewer mice contained live parasites, suggesting that there was efficient but not complete parasite elimination. DNA vaccine immunotherapy was also evaluated in CD1 mice infected with a low dose (5 × 102parasites) as a model of chronic infection. Immunotherapy was initiated on day 70 postinfection and resulted in improved survival and reduced cardiac tissue inflammation. These results suggest that DNA vaccines have strong potential for the immunotherapy ofT. cruziinfection and may provide new alternatives for the control of Chagas' disease.
Urokinase-Deficient Mice Fail To Generate a Type 2 Immune Response following Schistosomal Antigen Challenge
Authors: Gyetko Margaret R. , Sud Sudha , Chensue Stephen W. 
Published: December 2003

ABSTRACTActivated lymphocytes express urokinase-type plasminogen activator (uPA). Previous work suggests that uPA modulates T-lymphocyte responses. Mice deficient in uPA (uPA−/−) fail to generate type 1 (T1) immune responses during infection withCryptococcus neoformans. Failure to generate either a T1 or a T2 immune response is not predictive of defects in the alternative response. Conversely, down-regulation of one type of immune response may result in inappropriate overactivation of the other. It is not known whether the immune defect in uPA−/−mice affects only T1 responses or whether T2 responses are also impaired. Impairment of both T1 and T2 responses would suggest a global T-cell defect in the absence of uPA. To determine the role of uPA in T2 immune responses, wild-type (WT) and uPA−/−mice were primed and challenged with schistosomal egg antigen (SEA). This elicits strong polarization to T2 immune responses in immunocompetent mice. The challenged WT mice developed delayed-type hypersensitivity (DTH) to SEA; high levels of serum immunoglobulin E (IgE); a strong T2 cytokine phenotype with markedly elevated levels of interleukin-4 (IL-4), IL-5, and IL-13; and eosinophil-rich pulmonary granulomas. uPA−/−mice failed to develop DTH to SEA; did not polarize Ig production to IgE; did not produce high levels of IL-4, IL-5, or IL-13; and had markedly reduced numbers of granuloma-associated eosinophils. uPA−/−mice fail to generate polarized T2 immune responses to a T2-inducing pathogen. These findings, in conjunction with our previous work, demonstrate that mice deficient in uPA have profoundly impaired immunity involving both T1 and T2 polarization and are largely immunologically unresponsive.
Role of Neutrophils in Murine Salmonellosis
Authors: Cheminay Cédric , Chakravortty Dipshikha , Hensel Michael 
Published: December 2003

ABSTRACTGastrointestinal infections withSalmonella entericaserovars have different clinical outcomes that range from localized inflammation to a life-threatening systemic disease in the case of typhoid fever. Using a mouse model of systemic salmonellosis, we investigated the contribution of neutrophils to the innate immune defense againstSalmonellaafter oral infection. Neutrophil infiltration was dependent on the bacterial burden in various infected organs (Peyer's patches, mesenteric lymph nodes, spleen, and liver). However, the massive infiltration of neutrophils did not allow clearance of an infection with wild-typeSalmonella, presumably due to protection of intracellularSalmonellaagainst neutrophil activities. ASalmonellamutant strain deficient inSalmonellapathogenicity island 2 (SPI2) was able to infect systemic sites, but its replication was highly restricted and it did not cause detectable attraction of neutrophils. Neutrophil depletion by antibody treatment of mice did not restore the virulence of SPI2 or auxotrophic mutant strains, supporting the hypothesis that attenuation of the strains is not due to greater susceptibility to neutrophil killing. Our observations reveal that neutrophils have completely different roles during systemic salmonellosis and localized gastrointestinal infections. In the latter conditions, rapid neutrophil attraction efficiently prevents the spread of the pathogen, whereas the neutrophil influx is delayed during systemic infections and cannot protect against lethal bacteremia.
TraJ-DependentEscherichia coliK1 Interactions with Professional Phagocytes Are Important for Early Systemic Dissemination of Infection in the Neonatal Rat
Authors: Hill Val T. , Townsend Stacy M. , Arias Robyn S. , Jenabi Jasmine M. , Gomez-Gonzalez Ignacio , Shimada Hiroyuki , Badger Julie L. 
Published: December 2003

ABSTRACTEscherichia coliis a major cause of neonatal bacterial sepsis and meningitis. We recently identified a gene,traJ, which contributes to the ability ofE. coliK1 to penetrate the blood-brain barrier in the neonatal rat. Because very little is known regarding the most critical step in disease progression, translocation to the gut and dissemination to the lymphoid tissues after a natural route of infection, we assessed the ability of atraJmutant to cause systemic disease in the neonatal rat. Our studies determined that thetraJmutant is significantly less virulent than the wild type in the neonatal rat due to a decreased ability to disseminate from the mesenteric lymph nodes to the deeper tissues of the liver and spleen and to the blood during the early stages of systemic disease. Histopathologic studies determined that although significantly less or no mutant bacteria were recovered from the spleen and livers of infected neonatal rats, the inflammatory response was considerably greater than that in wild-type-colonized tissues. In vitro studies revealed that macrophages internalize thetraJmutant less frequently than they do the wild type and by a morphologically distinct process. Furthermore, we determined that tissue macrophages and dendritic cells within the liver and spleen are the major cellular targets ofE. coliK1 and that TraJ significantly contributes to the predominantly intracellular nature ofE. coliK1 within these professional phagocytes exclusively during the early stages of systemic disease. These data indicate that, contrary to earlier indications,E. coliK1 resides within professional phagocytes, and this is essential for the efficient progression of systemic disease.