bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parenchymal Organ, and Not Splenic, Immunity Correlates with Host Survival during Disseminated Candidiasis
Authors: Spellberg Brad , Johnston Douglas , Phan Quynh Trang , Edwards John E. , French Samuel W. , Ibrahim Ashraf S. , Filler Scott G. 
Published: September 2003

ABSTRACTWe examined the relationship between host survival and renal and splenic immune responses in a murine model of hematogenously disseminated candidiasis. Male BALB/c mice were infected via tail vein injection with wild-typeC. albicansor with an isogenic, Δefg1/Δefg1hypha-deficient mutant. Host survival, organ fungal burden, intracellular cytokine content of splenic and kidney lymphocytes, and whole-organ cytokine profiles were determined. Wild-typeC. albicansinduced type 2 splenocyte responses with both nonfatal and fatal inocula. In the kidney, conversely, wild-type inocula causing no or low mortality induced type 1 responses and 100% fatal inocula induced type 2 or interleukin-10 (IL-10)-dominant responses. Hypha-deficient mutantC. albicanscaused no or low mortality while inducing type 1 responses in both the spleen and kidney. To our knowledge, this is the first demonstration that host survival during systemic infection correlates with the type of immune response engendered in a nonlymphoid, parenchymal organ and not with the response in the spleen. Furthermore, the results provide in vivo confirmation that hyphal formation byC. albicansinduces type 2 or IL-10-dominant host responses in tissues.
Rapid Displacement of
Cryptosporidium parvum
Type 1 by Type 2 in Mixed Infections in Piglets
Authors: Akiyoshi Donna E. , Mor Siobhan , Tzipori Saul 
Published: September 2003

ABSTRACT

Genotypes 1 and 2 of
Cryptosporidium parvum
are the primary types associated with infections in humans, with type 1 being by far the predominant genotype. The frequency of mixed infection with both genotypes in humans is relatively rare, while type 1, which experimentally infects other mammals, has been found to naturally infect almost exclusively humans. One possible explanation for the absence of type 1 in other mammals and the low frequency of mixed infections in humans is the inability of type 1 to compete with type 2 in nature when both occur simultaneously. To investigate this, we challenged gnotobiotic piglets with equal number of oocysts of type 1 and type 2, given either simultaneously or with type 2 given 24 or 48 h after type 1. The genotype of the oocysts excreted in feces and the relative distribution of each of the genotypes throughout the gut at necropsy were determined. Regardless of the time interval between challenges with the two genotypes, type 2 invariably displaced type 1. The rate of displacement was rapid when both genotypes were given simultaneously, after which no traces of type 1 were detected in the feces or in gut sections by PCR. Infection with type 1 24 or 48 h before challenge with type 2, while permitting type 1 to become established, was still rapidly eliminated within 3 days after challenge with type 2. These observations have major implications regarding the relative perpetuation and survival of these two genotypes in mammals.
Identification of Two Eukaryote-Like Serine/Threonine Kinases Encoded by
Chlamydia trachomatis
Serovar L2 and Characterization of Interacting Partners of Pkn1
Authors: Verma Anita , Maurelli Anthony T. 
Published: September 2003

ABSTRACT

Genome sequencing of
C. trachomatis
serovar D revealed the presence of three putative open reading frames (ORFs), CT145 (Pkn1), CT673 (Pkn5), and CT301 (PknD), encoding eukaryote-like serine/threonine kinases (Ser/Thr kinases). Two of these putative kinase genes, CT145 and CT301, were PCR amplified from serovar L2, cloned, and sequenced. Predicted translation products of the ORFs showed the presence of conserved kinase motifs at the N terminus of the proteins. CT145 and CT301 (encoding Pkn1 and PknD, respectively) were expressed in
Escherichia coli
as GST fusion proteins. In vitro kinase assays with
Escherichia coli
-derived glutathione
S
-transferase fusion proteins showed autophosphorylation of Pkn1 and PknD, indicating that they are functional kinases. Gene expression analysis of these kinase genes in
Chlamydia
by reverse transcriptase PCR indicated expression of these kinases at the early mid phase of the developmental cycle. Immunoprecipitated native chlamydial Pkn1 and PknD proteins also showed autophosphorylation in an in vitro kinase assay. Phosphoamino acid analysis by thin-layer chromatography confirmed that Pkn1 and PknD are phosphorylated on both serine and threonine residues. Interaction of Pkn1 and PknD with each other as well as interaction of Pkn1 with inclusion membrane protein G (IncG) was demonstrated by using a bacterial two-hybrid system. These interactions were further suggested by phosphorylation of the proteins in in vitro kinase assays. This report is the first description of the existence of functional Ser/Thr kinases in
Chlamydia
. The results of these findings should lead to a better understanding of how
Chlamydia
interact and interfere with host signaling pathways, since kinases represent potential mediators of the intimate host-pathogen interactions that are essential to the intracellular life cycle of
Chlamydia.
ThePseudomonas aeruginosaAutoinducerN-3-Oxododecanoyl Homoserine Lactone Accelerates Apoptosis in Macrophages and Neutrophils
Authors: Tateda Kazuhiro , Ishii Yoshikazu , Horikawa Manabu , Matsumoto Tetsuya , Miyairi Shinichi , Pechere Jean Claude , Standiford Theodore J. , Ishiguro Masaji , Yamaguchi Keizo 
Published: September 2003

ABSTRACTQuorum-sensing systems are critical regulators of the expression of virulence factors of various organisms, includingPseudomonas aeruginosa. Las and Rhl are two major quorum-sensing components, and they are regulated by their corresponding autoinducers,N-3-oxododecanoyl homoserine lactone (3-oxo-C12-HSL) andN-butyryl-l-homoserine lactone (C4-HSL). Recent progress has demonstrated the potential of quorum-sensing molecules, especially 3-oxo-C12-HSL, for modulation of the host immune system. Here we show the specific ability of 3-oxo-C12-HSL to induce apoptosis in certain types of cells. When bone marrow-derived macrophages were incubated with synthetic 3-oxo-C12-HSL, but when they were incubated not C4-HSL, significant loss of viability was observed in a concentration (12 to 50 μM)- and incubation time (1 to 24 h)-dependent manner. The cytotoxic activity of 3-oxo-C12-HSL was also observed in neutrophils and monocytic cell lines U-937 and P388D1 but not in epithelial cell lines CCL-185 and HEp-2. Cells treated with 3-oxo-C12-HSL revealed morphological alterations indicative of apoptosis. Acceleration of apoptosis in 3-oxo-C12-HSL-treated cells was confirmed by multiple criteria (caspases 3 and 8, histone-associated DNA fragments, phosphatidylserine expression). Structure-activity correlation experiments demonstrated that the fine structure of 3-oxo-C12-HSL, the HSL backbone, and side chain length are required for maximal activity. These data suggest thatPseudomonas3-oxo-C12-HSL specifically promotes induction of apoptosis, which may be associated with 3-oxo-C12-HSL-induced cytotoxicity in macrophages and neutrophils. Our data suggest that the quorum-sensing molecule 3-oxo-C12-HSL has critical roles in the pathogenesis ofP. aeruginosainfection, not only in the induction of bacterial virulence factors but also in the modulation of host responses.
Role of Alternative Oxidase Gene in Pathogenesis of
Cryptococcus neoformans
Authors: Akhter Shamima , McDade Henry C. , Gorlach Jenifer M. , Heinrich Garrett , Cox Gary M. , Perfect John R. 
Published: September 2003

ABSTRACT

We identified a homologue of the alternative oxidase gene in a screen to identify genes that are preferentially transcribed in response to a shift to 37°C in the human-pathogenic yeast
Cryptococcus neoformans
. Alternative oxidases are nucleus-encoded mitochondrial proteins that have two putative roles: they can function in parallel with the classic cytochrome oxidative pathway to produce ATP, and they may counter oxidative stress within the mitochondria. The
C. neoformans
alternative oxidase gene (
AOX1
) was found to exist as a single copy in the genome, and it encodes a putative protein of 401 amino acids. An
aox1
mutant strain was created using targeted gene disruption, and the mutant strain was reconstituted to wild type using a full-length
AOX1
. Compared to both the wild-type and reconstituted strains, the
aox1
mutant strain was not temperature sensitive but did have significant impairment of both respiration and growth when treated with inhibitors of the classic cytochrome oxidative pathway. The
aox1
mutant strain was also found to be more sensitive to the oxidative stressor tert-butyl hydroperoxide. The
aox1
mutant strain was significantly less virulent than both the wild type and the reconstituted strain in the murine inhalational model, and it also had significantly impaired growth within a macrophage-like cell line. These data demonstrate that the alternative oxidase of
C. neoformans
can make a significant contribution to metabolism, has a role in the yeast's defense against exogenous oxidative stress, and contributes to the virulence composite of this organism, possibly by improving survival within phagocytic cells.
Molecular Characterization of the Acute Inflammatory Response to Infections with Gram-Negative versus Gram-Positive Bacteria
Authors: Feezor Robert J. , Oberholzer Caroline , Baker Henry V. , Novick Daniela , Rubinstein Menachem , Moldawer Lyle L. , Pribble John , Souza Sonia , Dinarello Charles A. , Ertel Wolfgang , Oberholzer Andreas 
Published: September 2003

ABSTRACTSepsis caused by gram-negative bacteria and that caused by gram-positive bacteria often manifest similar clinical features. We investigated plasma proinflammatory cytokine profiles in patients with sepsis due to gram-positive and gram-negative bacteria and studied the cytokine production and differential gene regulation of leukocytes stimulated ex vivo withEscherichia colilipopolysaccharide or heat-killedStaphylococcus aureus. Concentrations of tumor necrosis factor alpha, interleukin 1 receptor antagonist (IL-1Ra), IL-8, IL-10, IL-18 binding protein, procalcitonin, and protein C in plasma did not differ between patients with sepsis due to gram-negative and gram-positive bacteria. However, plasma IL-1β, IL-6, and IL-18 concentrations were significantly higher in patients with sepsis due to gram-positive bacteria. Ex vivo stimulation of whole blood with heat-killedS. aureusmarkedly increased IL-1β and IL-18 levels more thanE. colilipopolysaccharide stimulation. Microarray analysis revealed at least 359 cross-validated probe sets (genes) significant at theP< 0.001 level whose expression discriminated among gram-negative-organism-stimulated, gram-positive-organism-stimulated, and unstimulated whole-blood leukocytes. The host inflammatory responses to gram-negative and gram-positive stimuli share some common response elements but also exhibit distinct patterns of cytokine appearance and leukocyte gene expression.
Chlamydia pneumoniaeActivates Epithelial Cell Proliferation via NF-κB and the Glucocorticoid Receptor
Authors: Gencay Mikael M. Cornelsen , Tamm Michael , Glanville Allan , Perruchoud André P. , Roth Michael 
Published: September 2003

ABSTRACTChlamydia pneumoniaeis an obligate intracellular eubacterium and a common cause of acute and chronic respiratory tract infections. This study was designed to show the effect ofC. pneumoniaeon transcription factor activation in epithelial cells. The activation of transcription factors byC. pneumoniaewas determined in human epithelial cell lines (HL and Calu3) by electrophoretic DNA mobility shift assay, Western blotting, and luciferase reporter gene assay. The activation of transcription factors was further confirmed by immunostaining ofC. pneumoniae-infected HL cells and mock-infected controls. The effect of transcription factors onC. pneumoniae-induced host cell proliferation was assessed by [3H]thymidine incorporation and direct cell counting in the presence and absence of antisense oligonucleotides targeting transcription factors or the glucocorticoid receptor (GR) antagonist RU486. The activation of the GR, CCAAT-enhancer binding protein (C/EBP), and NF-κB was induced within 1 to 6 h byC. pneumoniae. While the interleukin-6 promoter was not activated byC. pneumoniae, the GR-driven p21(Waf1/Cip1)promoter was increased 2.5- to 3-fold over controls 24 h after infection.C. pneumoniaedose-dependently increased the DNA synthesis of the host cells 2.5- to 2.9-fold, which was partly inhibited either by RU486 or by NF-κB antisense oligonucleotides. Furthermore, we provide evidence that heat-inactivatedC. pneumoniaedoes not cause a significant increase in cell proliferation. Our results demonstrate thatC. pneumoniaeactivates C/EBP-β, NF-κB, and the GR in infected cells. However, only NF-κB and the GR were involved inC. pneumoniae-induced proliferation of epithelial cells.
M1 Protein Triggers a Phosphoinositide Cascade for Group A
Streptococcus
Invasion of Epithelial Cells
Authors: Purushothaman Sai Sudha , Wang Beinan , Cleary P. Patrick 
Published: September 2003

ABSTRACT

Invasion of nonphagocytic cells by bacteria provides a favorable niche for persistence and evasion of host defenses and antibiotics. M protein is a major virulence factor because it promotes high-frequency invasion of epithelial cells by group A
Streptococcus
(GAS) and also renders the bacterium resistant to phagocytosis. In this study, we investigated the role of M1 protein from serotype M1 strain 90-226 in regulating mammalian signal transduction and cytoskeletal rearrangement for bacterial entry. LY294002 and wortmannin, which are inhibitors of phosphatidylinositol 3-kinase (PI 3-K) blocked invasion of epithelial cells by GAS by 75 and 80%, respectively, but failed to inhibit invasion by
Salmonella enterica
serovar Typhimurium. Also, epithelial cells transiently transfected with dominant negative p85 and p110 genes, the regulatory and catalytic subunits of PI 3-K, respectively, were less able to be invaded by GAS. To separate the influence of other streptococcal virulence factors from M protein,
Lactococcus lactis
was engineered to express M1 protein on its surface.
L. lactis
(pLM1) invaded epithelial cells efficiently in vitro, and PI 3-K inhibitors blocked 90% of this invasion. Purified soluble M1 protein stimulated the formation of stress fibers and actin tuffs on epithelial cells. LY294002 and wortmannin inhibited these cellular changes. A phosphoinositide analogue also inhibited the invasion of epithelial cells by GAS. Therefore, M1 protein, either directly or via bound fibronectin, initiates signals that depend on the lipid kinase PI 3-K pathway, which paves the way for cytoskeletal rearrangement that internalize the bacterium.
ExperimentalMycobacterium tuberculosisInfection of Cynomolgus Macaques Closely Resembles the Various Manifestations of HumanM. tuberculosisInfection
Authors: Capuano Saverio V. , Croix Denise A. , Pawar Santosh , Zinovik Angelica , Myers Amy , Lin Philana L. , Bissel Stephanie , Fuhrman Carl , Klein Edwin , Flynn JoAnne L. 
Published: September 2003

ABSTRACTNonhuman primates were used to develop an animal model that closely mimics humanMycobacterium tuberculosisinfection. Cynomolgus macaques were infected with low doses of virulentM. tuberculosisvia bronchoscopic instillation into the lung. All monkeys were successfully infected, based on tuberculin skin test conversion and peripheral immune responses toM. tuberculosisantigens. Progression of infection in the 17 monkeys studied was variable. Active-chronic infection, observed in 50 to 60% of monkeys, was characterized by clear signs of infection or disease on serial thoracic radiographs and in other tests and was typified by eventual progression to advanced disease. Approximately 40% of monkeys did not progress to disease in the 15 to 20 months of study, although they were clearly infected initially. These monkeys had clinical characteristics of latent tuberculosis in humans. Low-dose infection of cynomolgus macaques appears to represent the full spectrum of humanM. tuberculosisinfection and will be an excellent model for the study of pathogenesis and immunology of this infection. In addition, this model will provide an opportunity to study the latentM. tuberculosisinfection observed in ∼90% of all infected humans.
Widespread Bronchogenic Dissemination Makes DBA/2 Mice More Susceptible than C57BL/6 Mice to Experimental Aerosol Infection withMycobacterium tuberculosis
Authors: Cardona Pere-Joan , Gordillo Sergi , Díaz Jorge , Tapia Gustavo , Amat Isabel , Pallarés Ángeles , Vilaplana Cristina , Ariza Aurelio , Ausina Vicenç 
Published: September 2003

ABSTRACTWe have used the murine model of aerosol-induced experimental tuberculosis to assess the effects of four clinical isolates and a reference strain ofMycobacterium tuberculosison resistant C57BL/6 mice and susceptible DBA/2 mice. Histological studies and detection of 25 cytokines potentially involved in the infection were carried out. DBA/2 mice showed higher concentrations of bacilli in bronchoalveolar lavage fluid and lung tissue. Furthermore, these mice evidenced a larger granulomatous infiltration in the parenchyma due to an increased rate of emigration of infected foamy macrophages from the granulomas to the neighboring pulmonary alveolar spaces. The better control of bacillary concentrations and pulmonary infiltration observed in C57BL/6 mice from week 3 postinfection could result from their higher RANTES, ICAM-1, and gamma interferon (IFN-γ) mRNA levels. On the other hand, the higher MIP-2 and MCP-3 mRNA levels seen in DBA/2 mice would result in stronger lung recruitment of macrophages and neutrophils. Additionally, DBA/2 mice showed increased inducible nitric oxide synthase expression, induced by the larger number of foamy macrophages, at weeks 18 and 22. This increment was a consequence of phagocytosed bacillary debris, was independent of IFN-γ expression, and could exert only a bacteriostatic effect. The results of the study suggest that DBA/2 mice are more susceptible than C57BL/6 mice toM. tuberculosisinfection due to a higher bronchial dissemination of bacilli inside poorly activated foamy macrophages.
Rab GTPases Are Recruited to Chlamydial Inclusions in Both a Species-Dependent and Species-Independent Manner
Authors: Rzomp Kimberly A. , Scholtes Luella D. , Briggs Benjamin J. , Whittaker Gary R. , Scidmore Marci A. 
Published: September 2003

ABSTRACT

Chlamydiae are obligate intracellular bacteria that replicate within an inclusion that is trafficked to the peri-Golgi region where it fuses with exocytic vesicles. The host and chlamydial proteins that regulate the trafficking of the inclusion have not been identified. Since Rab GTPases are key regulators of membrane trafficking, we examined the intracellular localization of several green fluorescent protein (GFP)-tagged Rab GTPases in chlamydia-infected HeLa cells. GFP-Rab4 and GFP-Rab11, which function in receptor recycling, and GFP-Rab1, which functions in endoplasmic reticulum (ER)-to-Golgi trafficking, are recruited to
Chlamydia trachomatis
,
Chlamydia muridarum
, and
Chlamydia pneumoniae
inclusions, whereas GFP-Rab5, GFP-Rab7, and GFP-Rab9, markers of early and late endosomes, are not. In contrast, GFP-Rab6, which functions in Golgi-to-ER and endosome-to-Golgi trafficking, is associated with
C. trachomatis
inclusions but not with
C. pneumoniae
or
C. muridarum
inclusions, while the opposite was observed for the Golgi-localized GFP-Rab10. Colocalization studies between transferrin and GFP-Rab11 demonstrate that a portion of GFP-Rab11 that localizes to inclusions does not colocalize with transferrin, which suggests that GFP-Rab11's association with the inclusion is not mediated solely through Rab11's association with transferrin-containing recycling endosomes. Finally, GFP-Rab GTPases remain associated with the inclusion even after disassembly of microtubules, which disperses recycling endosomes and the Golgi apparatus within the cytoplasm, suggesting a specific interaction with the inclusion membrane. Consistent with this, GFP-Rab11 colocalizes with
C. trachomatis
IncG at the inclusion membrane. Therefore, chlamydiae recruit key regulators of membrane trafficking to the inclusion, which may function to regulate the trafficking or fusogenic properties of the inclusion.
Citrobacter koseriBrain Abscess in the Neonatal Rat: Survival and Replication within Human and Rat Macrophages
Authors: Townsend Stacy M. , Pollack Harvey A. , Gonzalez-Gomez Ignacio , Shimada Hiroyuki , Badger Julie L. 
Published: September 2003

ABSTRACTA unique feature ofCitrobacter koseriis the extremely high propensity to initiate brain abscesses during neonatal meningitis. Previous clinical reports and studies on infant rats have documented manyCitrobacter-filled macrophages within the ventricles and brain abscesses. It has been hypothesized that intracellular survival and replication within macrophages may be a mechanism by whichC. koserisubverts the host response and elicits chronic infection, resulting in brain abscess formation. In this study, we showed thatC. kosericauses meningitis and brain abscesses in the neonatal rat model, and we utilized histology and magnetic resonance imaging technology to visualize brain abscess formation. Histology and electron microscopy (EM) revealed that macrophages (and not fibroblasts, astrocytes, oligodendrocytes, or neurons) were the primary target for long-termC. koseriinfection. To better understandC. koseripathogenesis, we have characterized the interactions ofC. koseriwith human macrophages. We found thatC. koserisurvives and replicates within macrophages in vitro and that uptake ofC. koseriincreases in the presence of human pooled serum in a dose-dependent manner. EM studies lend support to the hypothesis thatC. koseriuses morphologically different methods of uptake to enter macrophages. FcγRI blocking experiments show that this receptor primarily facilitates the entry of opsonizedC. koseriinto macrophages. Further, confocal fluorescence microscopy demonstrates thatC. koserisurvives phagolysosomal fusion and that more than 90% of intracellularC. koseriorganisms are colocalized within phagolysosomes. The ability ofC. koserito survive phagolysosome fusion and replicate within macrophages may contribute to the establishment of chronic central nervous system infection including brain abscesses.