bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mycolactone-Mediated Inhibition of Tumor Necrosis Factor Production by Macrophages Infected withMycobacterium ulceransHas Implications for the Control of Infection
Authors: Torrado Egídio , Adusumilli Sarojini , Fraga Alexandra G. , Small Pamela L. C. , Castro António G. , Pedrosa Jorge 
Published: May 2007

ABSTRACTThe pathogenicity ofMycobacterium ulcerans, the agent of Buruli ulcer, depends on the cytotoxic exotoxin mycolactone. Little is known about the immune response to this pathogen. Following the demonstration of an intracellular growth phase in the life cycle ofM. ulcerans, we investigated the production of tumor necrosis factor (TNF) induced by intramacrophage bacilli of diverse toxigenesis/virulence, as well as the biological relevance of TNF duringM. ulceransexperimental infections. Our data show that murine bone marrow-derived macrophages infected with mycolactone-negative strains ofM. ulcerans(nonvirulent) produce high amounts of TNF, while macrophages infected with mycolactone-positive strains of intermediate or high virulence produce intermediate or low amounts of TNF, respectively. These results are in accordance with the finding that TNF receptor P55-deficient (TNF-P55 KO) mice are not more susceptible than wild-type mice to infection by the highly virulent strains but are more susceptible to nonvirulent and intermediately virulent strains, demonstrating that TNF is required to control the proliferation of these strains in animals experimentally infected byM. ulcerans. We also show that mycolactone produced by intramacrophageM. ulceransbacilli inhibits, in a dose-dependent manner, but does not abrogate, the production of macrophage inflammatory protein 2, which is consistent with the persistent inflammatory responses observed in experimentally infected mice.
The Large Clostridial Toxins from
Clostridium sordellii
and
C. difficile
Repress Glucocorticoid Receptor Activity
Authors: Tait A. Sasha , Dalton Monique , Geny Blandine , D'Agnillo Felice , Popoff Michel R. , Sternberg Esther M. 
Published: May 2007

ABSTRACT

We have previously shown that
Bacillus anthracis
lethal toxin represses glucocorticoid receptor (GR) transactivation. We now report that repression of GR activity also occurs with the large clostridial toxins produced by
Clostridium sordellii
and
C. difficile
. This was demonstrated using a transient transfection assay system for GR transactivation. We also report that
C. sordellii
lethal toxin inhibited GR function in an ex vivo assay, where toxin reduced the dexamethasone suppression of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). Furthermore, the glucocorticoid antagonist RU-486 in combination with
C. sordellii
lethal toxin additively prevented glucocorticoid suppression of TNF-α. These findings corroborate the fact that GR is a target for the toxin and suggest a physiological role for toxin-associated GR repression in inflammation. Finally, we show that this repression is associated with toxins that inactivate p38 mitogen-activated protein kinase (MAPK).
Multiple Consecutive Lavage Samplings Reveal Greater Burden of Disease and Provide Direct Access to the Nontypeable
Haemophilus influenzae
Biofilm in Experimental Otitis Media
Authors: Leroy Magali , Cabral Howard , Figueira Marisol , Bouchet Valérie , Huot Heather , Ram Sanjay , Pelton Stephen I. , Goldstein Richard 
Published: May 2007

ABSTRACT

The typically recovered quantity of nontypeable
Haemophilus influenzae
(NTHi) bacteria in an ex vivo middle ear (ME) aspirate from the chinchilla model of experimental otitis media is insufficient for direct analysis of gene expression by microarray or of lipopolysaccharide glycoforms by mass spectrometry. This prompted us to investigate a strategy of multiple consecutive lavage samplings to increase ex vivo bacterial recovery. As multiple consecutive lavage samples significantly increased the total number of bacterial CFU collected during nasopharyngeal colonization or ME infection, this led us to evaluate whether bacteria sequentially acquired from consecutive lavages were similar. Comparative observation of complete ex vivo sample series by microscopy initially revealed ME inflammatory fluid consisting solely of planktonic-phase NTHi. In contrast, subsequent lavage samplings of the same infected ear revealed the existence of bacteria in two additional growth states, filamentous and biofilm encased. Gene expression analysis of such ex vivo samples was in accord with different bacterial growth phases in sequential lavage specimens. The existence of morphologically distinct NTHi subpopulations with varying levels of gene expression indicates that the pooling of specimens requires caution until methods for their separation are developed. This study based on multiple consecutive lavages is consistent with prior reports that NTHi forms a biofilm in vivo, describes the means to directly acquire ex vivo biofilm samples without sacrificing the animal, and has broad applicability for a study of mucosal infections. Moreover, this approach revealed that the actual burden of bacteria in experimental otitis media is significantly greater than was previously reported. Such findings may have direct implications for antibiotic treatment and vaccine development against NTHi.
Uropathogenic
Escherichia coli
Outer Membrane Antigens Expressed during Urinary Tract Infection
Authors: Hagan Erin C. , Mobley Harry L. T. 
Published: May 2007

ABSTRACT

Uncomplicated urinary tract infection (UTI) caused by uropathogenic
Escherichia coli
(UPEC) represents a prevalent and potentially severe infectious disease. In this study, we describe the application of an immunoproteomics approach to vaccine development that has been used successfully to identify vaccine targets in other pathogenic bacteria. Outer membranes were isolated from pyelonephritis strain
E. coli
CFT073 cultured under conditions that mimic the urinary tract environment, including iron limitation, osmotic stress, human urine, and exposure to uroepithelial cells. To identify antigens that elicit a humoral response during experimental UTI, outer membrane proteins were separated by two-dimensional gel electrophoresis and probed using pooled antisera from 20 CBA/J mice chronically infected with
E. coli
CFT073. In total, 23 outer membrane antigens, including a novel iron compound receptor, reacted with the antisera and were identified by mass spectrometry. These antigens also included proteins with known roles in UPEC pathogenesis, such as ChuA, IroN, IreA, Iha, IutA, and FliC. These data demonstrate that an antibody response is directed against these virulence-associated factors during UTI. We also show that the genes encoding ChuA, IroN, hypothetical protein c2482, and IutA are significantly more prevalent (
P
< 0.01) among UPEC strains than among fecal-commensal
E. coli
isolates. Thus, we suggest that the conserved outer membrane antigens identified in this study could be rational candidates for a UTI vaccine designed to elicit protective immunity against UPEC infection.
Exogenous Farnesol Interferes with the Normal Progression of Cytokine Expression during Candidiasis in a Mouse Model
Authors: Navarathna Dhammika H. M. L. P. , Nickerson Kenneth W. , Duhamel Gerald E. , Jerrels Thomas R. , Petro Thomas M. 
Published: May 2007

ABSTRACTCandida albicans, a dimorphic fungus composed of yeast and mycelial forms, is the most common human fungal pathogen. Th1 cytokines such as interleukin-2 (IL-2), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α), which are induced by macrophage IL-12, are critical to resistance against systemic candidiasis, while Th2 cytokines such as IL-4 and IL-5 are less critical. Farnesol is a quorum-sensing molecule produced byC. albicansthat controls the formation of mycelia but is also a virulence factor. To determine whether farnesol enhances the virulence ofC. albicansby modulating the production of Th1 and Th2 cytokines, mice were pretreated with farnesol prior to intravenous infection with a sublethal dose of farnesol-producingC. albicans. Production of IL-2, IL-4, IL-5, TNF-α, IFN-γ, and IL-12 was evaluated by bead-array flow cytometry and enzyme-linked immunosorbent assay. Mice exhibited an elevation in serum TNF-α levels at 48 h and an elevation in IFN-γ and IL-12 levels at 6 to 12 h after infection withC. albicans. Pretreatment with farnesol significantly reduced the elevation of both IFN-γ and IL-12 but not TNF-α. In contrast, mice pretreated with farnesol exhibited an unexpected elevation in IL-5 levels. To determine whether farnesol has a direct effect on macrophage production of IL-12, peritoneal macrophages were pretreated with farnesol prior to stimulation with IFN-γ plus lipopolysaccharide (LPS). Farnesol inhibited production of both IL-12 p40 and p70 from IFN-γ/LPS-stimulated macrophages. Therefore, the role of farnesol in systemic candidiasis is likely due to its ability to inhibit the critical Th1 cytokines IFN-γ and IL-12 and perhaps to enhance a Th2 cytokine, IL-5.
Identification of a LolC Homologue inBurkholderia pseudomallei, a Novel Protective Antigen for Melioidosis
Authors: Harland David N. , Chu Karen , Haque Ashraful , Nelson Michelle , Walker Nicola J. , Sarkar-Tyson Mitali , Atkins Timothy P. , Moore Benjamin , Brown Katherine A. , Bancroft Gregory , Titball Richard W. , Atkins Helen S. 
Published: May 2007

ABSTRACTMelioidosis is an emerging disease of humans in Southeast Asia and tropical Australia. The bacterium causing this disease,Burkholderia pseudomallei, is also considered a bioterrorism agent, and as yet there is no licensed vaccine for preventingB. pseudomalleiinfection. In this study, we evaluated selected proteins (LolC, PotF, and OppA) of the ATP-binding cassette systems ofB. pseudomalleias candidate vaccine antigens. Nonmembrane regions of theB. pseudomalleiproteins were expressed and purified fromEscherichia coliand then evaluated as vaccine candidates in an established mouse model ofB. pseudomalleiinfection. When delivered with the monophosphoryl lipid A-trehalose dicorynomycolate adjuvant, the proteins stimulated antigen-specific humoral and cellular immune responses. Immunization with LolC or PotF protein domains afforded significant protection against a subsequent challenge withB. pseudomallei. The most promising vaccine candidate, LolC, provided a greater level of protection when it was administered with immune-stimulating complexes complexed with CpG oligodeoxynucleotide 10103. Immunization with LolC also protected against a subsequent challenge with a heterologous strain ofB. pseudomallei, demonstrating the potential utility of this protein as a vaccine antigen for melioidosis.
Periodontal Bacterial DNA Suppresses the Immune Response to Mutans Streptococcal Glucosyltransferase
Authors: Taubman Martin A. , Han Xiaozhe , LaRosa Karen B. , Socransky Sigmund S. , Smith Daniel J. 
Published: May 2007

ABSTRACTCertain CpG motifs found in bacterial DNA enhance immune responses through Toll-like receptor 9 (TLR-9) and may also demonstrate adjuvant properties. Our objective was to determine if DNA from bacteria associated with periodontal disease could affect the immune response to other bacterial antigens in the oral cavity.Streptococcus sobrinusglucosyltransferase (GTF), an enzyme involved in dental caries pathogenesis, was used as a test antigen. Rowett rats were injected with aluminum hydroxide (alum) with buffer, alum-GTF, or alum-GTF together with eitherEscherichia coliDNA,Fusobacterium nucleatumDNA, orPorphyromonas gingivalisDNA. Contrary to expectation, animals receiving alum-GTF plus bacterial DNA (P. gingivalisin particular) demonstrated significantly reduced serum immunoglobulin G (IgG) antibody, salivary IgA antibody, and T-cell proliferation to GTF compared to animals immunized with alum-GTF alone. A diminished antibody response was also observed after administration of alum-GTF with theP. gingivalisDNA either together or separately, indicating that physical complexing of antigen and DNA was not responsible for the reduction in antibody. Since TLR triggering by DNA induces synthesis of prospective suppressive factors (e.g., suppressor of cytokine signaling [SOCS]), the effects ofP. gingivalisDNA and GTF exposure on rat splenocyte production of SOCS family molecules and inflammatory cytokines were investigated in vitro.P. gingivalisDNA significantly up-regulated SOCS1 and SOCS5 expression and down-regulated interleukin-10 expression by cultured splenocytes. These results suggested that DNA from periodontal disease-associated bacteria did not enhance, but in fact suppressed, the immune response to a protein antigen from cariogenic streptococci, potentially through suppressive SOCS components triggered by innate mechanisms.
Extracytoplasmic-Stress-Responsive Pathways Modulate Type III Secretion in
Yersinia pseudotuberculosis
Authors: Carlsson Katrin E. , Liu Junfa , Edqvist Petra J. , Francis Matthew S. 
Published: May 2007

ABSTRACT

Three signal transduction pathways, the two-component systems CpxRA and BaeSR and the alternative sigma factor σ
E
, respond to extracytoplasmic stress that facilitates bacterial adaptation to changing environments. At least the CpxRA and σ
E
pathways control the production of protein-folding and degradation factors that counter the effects of protein misfolding in the periplasm. This function also influences the biogenesis of multicomponent extracellular appendages that span the bacterial envelope, such as various forms of pili. Herein, we investigated whether any of these regulatory pathways in the enteropathogen
Yersinia pseudotuberculosis
affect the functionality of the Ysc-Yop type III secretion system. This is a multicomponent molecular syringe spanning the bacterial envelope used to inject effector proteins directly into eukaryotic cells. Disruption of individual components revealed that the Cpx and σ
E
pathways are important for
Y. pseudotuberculosis
type III secretion of Yops (
Yersinia
outer proteins). In particular, a loss of CpxA, a sensor kinase, reduced levels of structural Ysc (
Yersinia
secretion) components in bacterial membranes, suggesting that these mutant bacteria are less able to assemble a functional secretion apparatus. Moreover, these bacteria were no longer capable of localizing Yops into the eukaryotic cell interior. In addition, a
cpxA lcrQ
double mutant engineered to overproduce and secrete Yops was still impaired in intoxicating cells. Thus, the Cpx pathway might mediate multiple influences on bacterium-target cell contact that modulate
Yersinia
type III secretion-dependent host cell cytotoxicity.
Opa Proteins of Pathogenic Neisseriae Initiate Src Kinase-Dependent or Lipid Raft-Mediated Uptake via Distinct Human Carcinoembryonic Antigen-Related Cell Adhesion Molecule Isoforms
Authors: Schmitter Tim , Pils Stefan , Weibel Stephanie , Agerer Franziska , Peterson Lisa , Buntru Alexander , Kopp Kathrin , Hauck Christof R. 
Published: May 2007

ABSTRACTSeveral pathogenic bacteria exploit human carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) for adhesion to and invasion into their host cells. CEACAM isoforms have characteristic expression patterns on epithelial, endothelial, or hematopoietic cells, providing bacteria with distinct sets of receptors on particular tissues. For example, while CEACAM1 and CEACAM6 have a wide tissue distribution, CEACAM3, CEACAM4, and CEACAM8 are uniquely expressed on primary human granulocytes, whereas CEA and CEACAM7 are limited to epithelia. By reconstitution of a CEACAM-deficient cell line with individual CEACAMs, we have analyzed the requirements for CEACAM-mediated internalization ofNeisseria gonorrhoeae. Our results point to two mechanistically different uptake pathways triggered by either epithelial CEACAMs (CEACAM1, CEA, and CEACAM6) or the granulocyte-specific CEACAM3. In particular, CEACAM3-mediated uptake critically depends on Src family protein tyrosine kinase (PTK) activity, and CEACAM3 associates with the SH2 domains of several Src PTKs. In contrast, epithelial CEACAMs require the integrity of cholesterol-rich membrane microdomains and are affected by cholesterol depletion, whereas CEACAM3-mediated uptake by transfected cells or the opsonin-independent phagocytosis by human granulocytes is not altered in the presence of cholesterol chelators. These results allow the subdivision of all human CEACAMs known to be utilized as pathogen receptors into functional groups and point to important consequences for bacterial engagement of distinct CEACAM isoforms.
Toll-Like Receptor 2-Mediated Signaling Requirements forFrancisella tularensisLive Vaccine Strain Infection of Murine Macrophages
Authors: Cole Leah E. , Shirey Kari Ann , Barry Eileen , Santiago Araceli , Rallabhandi Prasad , Elkins Karen L. , Puche Adam C. , Michalek Suzanne M. , Vogel Stefanie N. 
Published: May 2007

ABSTRACTFrancisella tularensis, an aerobic, non-spore-forming, gram-negative coccobacillus, is the causative agent of tularemia. We reported previously thatF. tularensislive vaccine strain (LVS) elicited strong, dose-dependent NF-κB reporter activity in Toll-like receptor 2 (TLR2)-expressing HEK293T cells and proinflammatory gene expression in primary murine macrophages. Herein, we report thatF. tularensisLVS-induced murine macrophage proinflammatory cytokine gene and protein expression are overwhelmingly TLR2 dependent, as evidenced by the abrogated responses of TLR2−/−macrophages.F. tularensisLVS infection also increased expression of TLR2 both in vitro, in mouse macrophages, and in vivo, in livers fromF. tularensisLVS-infected mice. Colocalization of intracellularF. tularensisLVS, TLR2, and MyD88 was visualized by confocal microscopy. Signaling was abrogated if theF. tularensisLVS organisms were heat or formalin killed or treated with chloramphenicol, indicating that the TLR2 agonist activity is dependent on new bacterial protein synthesis.F. tularensisLVS replicates in macrophages; however, bacterial replication was not required for TLR2 signaling because LVSΔguaA, anF. tularensisLVSguanine auxotroph that fails to replicate in the absence of exogenous guanine, activated NF-κB in TLR2-transfected HEK293T cells and induced cytokine expression in wild-type macrophages comparably to wild-typeF. tularensisLVS. Collectively, these data indicate that the primary macrophage response toF. tularensisLVS is overwhelmingly TLR2 dependent, requires de novo bacterial protein synthesis, and is independent of intracellularF. tularensisreplication.
A continuous mental task decreases the physiological response to soccer-specific intermittent exercise
Authors: Greig Matt , Marchant David , Lovell Richard , Clough Peter , McNaughton Lars 
Published: May 2007

Background:Epidemiological findings of higher injury incidence during the latter stages of soccer match-play have been attributed to fatigue.Objective:To examine the interaction of physical and cognitive responses during soccer-specific intermittent exercise.Method:Ten semi-professional soccer players completed a 90-minute laboratory-based treadmill protocol replicating the activity profile of soccer match-play. Two separate trials were performed in randomised order, with and without the added stressor of a continuous grid-based vigilance task. The exercise task comprised six repetitions of a 15 minute activity profile, separated by a passive 15 minute half-time interval. The vigilance task required continual attention and sporadic target response within a letter grid. Physical response (RPE, heart rate, blood lactate, salivary cortisol) and cognitive performance (response time, response accuracy) were quantified at 15 minute intervals.Results:Completing the exercise task with the vigilance task resulted in decreased physiological (heart rate, blood lactate) response. This may be attributed to externally directed attention, resulting in association with the cognitive task and subsequent dissociation from the physical effort. Response speed generally improved with exercise duration, while there was evidence of impaired accuracy in the early stages of the first half and the latter stages of the second half.Conclusion:The interaction of physical and mental work was not additive in nature. The mental task had a masking effect on the physical response. Performing physical exercise tasks without due regard for appropriate psychological stimuli may therefore overestimate the physiological response.
Plasma testosterone levels of male European starlings (Sturnus vulgaris) during the breeding cycle and in relation to song and paternal care
Authors: Eens Marcel , Darras Veerle , Arckens Lutgarde , de Ridder Elke , Pinxten Rianne 
Published: May 2007

In temperate-zone birds, seasonal testosterone (T) profiles often vary among species with different mating systems. The trade-off hypothesis suggests that T levels in male birds represent a trade-off between additional mating effort, stimulated by high T, and paternal effort, inhibited by high T. To study the role of T in mediating the trade-off between paternal and mating effort in the facultatively polygynous European starling (
Sturnus vulgaris
), we monitored seasonal fluctuations in T levels and song activity, which functions mainly in mate attraction, and we investigated natural covariation between plasma T levels and male parental and song behaviour during the parental phase. T concentrations peaked during nest building, remained high during the fertile period, and then decreased gradually during the period of paternal care. This resembles the profile typically found in polygynous species with biparental care. Seasonal variation in song activity paralleled seasonal changes in T. The proportion of time spent incubating was significantly negatively correlated with T levels in individual males. There was a positive, but non-significant, correlation between song activity at an additional nest box and T levels during incubation. We suggest that this negative correlation between T and incubation behaviour may be partly explained by T increases in males responding to the presence of prospecting females with additional nestbox occupation and mate attraction song, rather than that high T levels stimulate mate attraction song. During the feeding period, characterized by a very low availability of unmated females, variation in T levels was low and there was no covariation between T and feeding. T levels during the parental phase reflect, but do not seem to directly regulate, the trade-off between parental and additional mating effort and other factors such as opportunities for additional matings may influence the resolution of this reproductive trade-off.
Female choice in the penduline tit Remiz pendulinus: the effects of nest size and male mask size
Authors: Pogány Ákos , Székely Tamás 
Published: May 2007

Why do females prefer some males over others? Females often use multiple cues, and to distinguish between these cues one needs to manipulate putative male traits. We carried out a test of multiple cues hypothesis in a polygamous bird, the penduline tit
Remiz pendulinus
. In this passerine both males and females mate with up to six mates within a breeding season, and a single parent (male or female) incubates the eggs and raises the chicks. Males build sophisticated nests, and previous studies suggested that females prefer males with large nest to small ones, since large nests provide direct benefit to females
via
reduced cost of incubation. Males sport wider eye-stripes ('masks') than females, and males with large masks find a mate faster than males with small masks. In a mate choice experiment using factorial design and two levels for each trait, we show that females prefer males with large masks, whereas they do not show preference for large nests. These results suggest that in penduline tits (i) females pay more attention to a trait that signals indirect benefit (mask size) than a trait that is related to direct benefits (nest size), and (ii) nest preference may be context-dependent.