bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased Levels of Soluble Fas Ligand in Serum in
Plasmodium falciparum
Malaria
Authors: Kern Peter , Dietrich Manfred , Hemmer Christoph , Wellinghausen Nele 
Published: July 2002

ABSTRACT

Levels of soluble Fas ligand (sFasL) in serum were elevated in patients with
Plasmodium falciparum
malaria and showed a significant decline during disease course. sFasL levels that were elevated before antimalarial treatment began correlated significantly with depressed total lymphocyte and T-cell counts. These data suggest that Fas-induced apoptosis might play a role in malaria-associated lymphopenia.
Antibody Interactions with the Capsule ofCryptococcus neoformans
Authors: Feldmesser Marta , Rivera Johanna , Kress Yvonne , Kozel Thomas R. , Casadevall Arturo 
Published: July 2002

ABSTRACTMonoclonal antibodies to the encapsulated fungusCryptococcus neoformansproduce different immunofluorescence (IF) patterns after binding to the polysaccharide capsule. To explore the relationship between the IF pattern and the location of antibody binding, two immunoglobulin M (IgM) monoclonal antibodies (MAbs) (12A1 and 13F1) that differ in protective efficacy and IF pattern and one protective IgG1 MAb (2H1) were studied by IF and electron microscopy (EM). FixingC. neoformanscells in lung tissue for EM resulted in significantly better preservation of the capsule than fixing yeast cells in suspension. The localization of MAbs 12A1 and 13F1 by immunogold EM differed depending on whether the MAb was bound to cells in cut tissue sections embedded in plastic or to cells in solution. In cut tissue sections, MAbs 12A1 and 13F1 bound throughout the capsule, whereas in solution both MAbs bound near the capsule surface. To investigate whether antibody binding to theC. neoformanscapsule affected the binding of other primary or secondary reagents, various combinations of MAbs 12A1, 13F1, and 2H1 were studied by direct and indirect IF. The IF pattern and location of binding for MAbs 12A1, 13F1, and 2H1 varied depending on the presence of other capsule-binding MAbs and the method of detection. The results show that (i) binding of MAbs to theC. neoformanspolysaccharide capsule can modify the binding of subsequent primary or secondary antibodies; (ii) the IgM MAbs bind primarily to the outer capsule regions despite the occurrence of their epitopes throughout the capsule; and (iii) MAb 2H1 staining of newly formed buds is reduced, suggesting quantitative or qualitative differences in bud capsule.
Vaccination with Calpain Induces a Th1-Biased Protective Immune Response againstSchistosoma japonicum
Authors: Zhang Renli , Yoshida Ayako , Kumagai Takashi , Kawaguchi Hitoshi , Maruyama Haruhiko , Suzuki Takashi , Itoh Makoto , El-Malky Mohamed , Ohta Nobuo 
Published: July 2002

ABSTRACTA large subunit of calpain, a calcium-activated neutral proteinase, fromSchistosoma japonicumwas cloned and expressed inEscherichia coli. When BALB/c mice were immunized with purified recombinant calpain (r-calpain) emulsified in complete Freund's adjuvant, a significant reduction in the number of recovered worms and also in egg production per female worm was observed(P < 0.01). Spleen cells of the immunized mice showed enhanced production of gamma interferon (IFN-γ) by activated CD4+T cells. Considering our observation of elevated expression of inducible nitric oxide synthase mRNA in immunized mice, r-calpain-induced IFN-γ seemed to upregulate the production of nitric oxide by macrophages and subsequently mediated the killing of schistosomulae in the lung. On the other hand, spleen cells of immunized mice showed only faint interleukin-4 production in response to r-calpain in vitro, suggesting that immunization with r-calpain alters the Th1-Th2 balance in murine hosts even during a Th2-promotingS. japonicuminfection. Furthermore, histopathological study of the livers of immunized mice showed that granulomas formed around eggs were diminished in both size and number. Egg production by female worms was clearly decreased in immunized mice, suggesting that r-calpain also has antifecundity effects. Taken together, these results point toS. japonicumcalpain as a potential vaccine candidate for both worm killing and disease prevention, possibly through the induction of a strong Th1-dominant environment in immunized mice.
Differential Interleukin-8 Response of Intestinal Epithelial Cell Line to Reactogenic and Nonreactogenic Candidate Vaccine Strains of
Vibrio cholerae
Authors: Rodrı́guez Boris L. , Rojas Armando , Campos Javier , Ledon Talena , Valle Edgar , Toledo William , Fando Rafael 
Published: July 2002

ABSTRACT

In this study, we analyzed whether attachment of
Vibrio cholerae
vaccine strains to human intestinal epithelial cells can induce an interleukin-8 (IL-8) response. The IL-8 transcripts were detected by PCR amplification of reverse-transcribed mRNA, and the gene product secretion was measured by an enzyme-linked immunosorbent assay. Infection of monolayers of the undifferentiated HT29-18N2 cell line with reactogenic (JBK70 and 81) and nonreactogenic (CVD103HgR and 638) vaccine strains of
V. cholerae
resulted in markedly higher IL-8 expression by epithelial cells exposed to reactogenic strains than by cells exposed to the nonreactogenic strains. Additionally, epithelial cells produced IL-8 transcripts following stimulation with cholera vaccine strains in a concentration-dependent manner. These results represent a new insight into the inflammatory component of reactogenicity and could be used as a predictive marker of vaccine reactogenicity prior to human testing.
Lysine and Polyamines Are Substrates for Transglutamination of Rho by the
Bordetella
Dermonecrotic Toxin
Authors: Schmidt Gudula , Goehring Udo-Michael , Schirmer Joerg , Uttenweiler-Joseph Sandrine , Wilm Matthias , Lohmann Mark , Giese Arnd , Schmalzing Guenther , Aktories Klaus 
Published: July 2002

ABSTRACT

Bordetella
dermonecrotic toxin (DNT) catalyzes the transglutamination of glutamine-63/61 of Rho GTPases, thereby constitutively activating Rho proteins. Here we identified second substrates for transglutamination of RhoA by DNT. The enzymatically active fragment of DNT (residues 1136 to 1451, ΔDNT) induced the incorporation of
l
-[
14
C]lysine in RhoA in a concentration-dependent manner. Also, Rac and Cdc42, but not Ras, were transglutaminated with lysine by ΔDNT. Transglutamination of the GTPase with
l
-lysine inhibited intrinsic and Rho-GAP-stimulated GTP hydrolysis of RhoA. In contrast to lysine, treatment of RhoA with alanine, arginine, and glutamine were not able to substitute for lysine in the transglutamination reaction. DNT increased the incorporation of
l
-[
14
C]lysine into embryonic bovine lung cells. Microinjection of GST-RhoA together with the enzymatically active DNT fragment into
Xenopus
oocytes, subsequent affinity purification of modified GST-RhoA, and mass spectrometry identified attachment of putrescine or spermidine at glutamine-63 of RhoA. A comparison of putrescine, spermidine, and lysine as substrates for DNT-induced transglutamination of RhoA revealed that lysine is a preferred second substrate at least in vitro.
Role of FliC and FliD Flagellar Proteins of
Clostridium difficile
in Adherence and Gut Colonization
Authors: Tasteyre Albert , Barc Marie-Claude , Collignon Anne , Boureau Helene , Karjalainen Tuomo 
Published: July 2002

ABSTRACT

In vitro and in vivo adhesive properties of flagella and recombinant flagellin FliC and flagellar cap FliD proteins of
Clostridium difficile
were analyzed. FliC, FliD, and crude flagella adhered in vitro to axenic mouse cecal mucus. Radiolabeled cultured cells bound to a high degree to FliD and weakly to flagella deposited on a membrane. The tissue association in the mouse cecum of a nonflagellated strain was 10-fold lower than that of a flagellated strain belonging to the same serogroup, confirming the role of flagella in adherence.
Mechanisms MediatingPorphyromonas gingivalisGingipain RgpA-Induced Oral Mucosa Inflammation In Vivo
Authors: Rubinstein Israel , Potempa Jan , Travis James , Gao Xiao-Pei 
Published: July 2002

ABSTRACTSuffusion of gingipain RgpA (GRgpA) elicited a significant concentration-dependent increase in the clearance of macromolecules from in situ hamster cheek pouch which was attenuated by NPC 17647, a selective bradykinin B2receptor antagonist. Leupeptin and a mixture of proteinase inhibitors also attenuated GRgpA-induced responses. These data indicate that GRgpA elicits plasma exudation from in situ oral mucosa in a catalytic site-dependent fashion by elaborating bradykinin.
Infectivity ofChlamydia trachomatisSerovar LGV but Not E Is Dependent on Host Cell Heparan Sulfate
Authors: Taraktchoglou Maria , Pacey Allan A. , Turnbull Jeremy E. , Eley Adrian 
Published: July 2002

ABSTRACTThe ability of heparan sulfate, heparin, and other glycosaminoglycans to inhibit the infectivity ofChlamydia trachomatisserovars E and LGV was examined using a simple competitive inhibition assay with three cell types from the human female reproductive tract, including primary human endosalpingeal cells. With the majority of the glycosaminoglycans tested, LGV was more significantly inhibited than serovar E. We have compared chlamydial infectivity between a wild-type Chinese hamster ovary cell line and two glycosaminoglycan-deficient cell lines. LGV was shown to be unable to infect heparan sulfate-deficient and GAG-deficient Chinese hamster ovary cell lines, whereas the E serovar infected these cells as efficiently as the control (nondeficient) cells. These two sets of experiments confirmed that serovar LGV is more dependent on a heparan sulfate-related mechanism of infectivity than is serovar E. This is further supported by the fact that attempts to purify a heparan sulfate-like molecule from either serovar cultured in glycosaminoglycan-deficient cell lines were nonproductive. Previous reports have suggested that chlamydia are able to produce a heparan sulfate-like molecule that is important for attachment and infectivity. We have attempted to detect possible binding of a specific heparan sulfate antibody toC. trachomatisby flow cytometry. Results showed no binding of the heparan sulfate antibody toC. trachomatisserovar LGV or E. Our results strongly indicate that chlamydiae do not produce a heparan sulfate-like molecule but rather use host cell heparan sulfate in order to infect cells.
Critical Role of CD14 for Production of Proinflammatory Cytokines and Cytokine Inhibitors during Sepsis with Failure To Alter Morbidity or Mortality
Authors: Ebong Samuel J. , Goyert Sanna M. , Nemzek Jean A. , Kim Jiyoun , Bolgos Gerald L. , Remick Daniel G. 
Published: July 2002

ABSTRACTWe investigated the immunopathophysiologic responses during sepsis induced by cecal ligation and puncture (CLP) in CD4-deficient (CD14 knockout [CD14KO]) mice. Our studies were designed to specifically test the role of CD14 in the inflammatory response to sepsis and to ascertain if alterations would improve morbidity or mortality. Sepsis was induced using the CLP model with appropriate antibiotic treatment. The severity of sepsis increased in the CD14KO mice with increasing puncture size (18 gauge [18G], 21G, and 25G). Following CLP, body temperature (at 12 h) and gross motor activity levels of the sham and 25G CLP groups recovered to normal, while the 21G and 18G CLP groups exhibited severe hypothermia coupled with decreased gross motor activity and body weight. There were no significant differences in survival, temperature, body weight, or activity levels between CD14KO and control mice after 21G CLP. However, CD14KO mice expressed two- to fourfold less pro-inflammatory (interleukin-1β [IL-1β], tumor necrosis factor [TNF], and IL-6) and anti-inflammatory (IL-10, IL-1 receptor antagonist, and TNF receptors I and II) cytokines in the blood after 21G CLP. Plasma levels of the chemokines macrophage inflammatory protein 2α and KC were similarly reduced in CD14KO mice. A similar trend of decreased cytokine and cytokine inhibitor levels was observed in the peritoneal cavity of CD14KO mice. Our results indicate that the CD14 pathway of activation plays a critical role in the production of both pro-inflammatory cytokines and cytokine inhibitors but has minimal impact on the morbidity or mortality induced by the CLP model of sepsis.
Apoptotic Signaling Pathway Activated by
Helicobacter pylori
Infection and Increase of Apoptosis-Inducing Activity under Serum-Starved Conditions
Authors: Shibayama Keigo , Doi Yohei , Shibata Naohiro , Yagi Tetsuya , Nada Toshi , Iinuma Yoshitsugu , Arakawa Yoshichika 
Published: July 2002

ABSTRACT

The enhanced gastric epithelial cell apoptosis observed during infection with
Helicobacter pylori
has been suggested to be of significance in the etiology of gastritis, peptic ulcers, and neoplasia. To investigate the cell death signaling induced by
H. pylori
infection, human gastric epithelial cells were incubated with
H. pylori
for up to 72 h.
H. pylori
infection induced the activation of caspase -8, -9, and -3 and the expression of the proapoptotic Bcl-2 family proteins Bad and Bid. The peak of the activity of the caspases occurred at 24 h. At this time, the inhibition of caspase-8 or -9 almost completely suppressed
H. pylori
-induced apoptosis. Inhibition of caspase-8 suppressed the expression of Bad and Bid and the subsequent activation of caspase-9 and -3. These observations indicate that
H. pylori
induces apoptosis through a pathway involving the sequential induction of apical caspase-8 activity, the proapoptotic proteins Bad and Bid, caspase-9 activity, and effector caspase-3 activity. Activation of the pathway was independent of CagA or vacuolating toxin. A membrane fraction of
H. pylori
was sufficient to activate this pathway, and treatment with proteinase K eliminated the activity. Apoptotic activity of the membrane fraction was significantly increased by incubating the bacteria under serum-starved conditions for 24 h. These observations suggest that environmental conditions in the human stomach could induce
H. pylori
-mediated pathogenesis, leading to a variety of clinical outcomes.
Complement Contributes to Protective Immunity against Reinfection byPlasmodium chabaudi chabaudiParasites
Authors: Taylor Philip R. , Seixas Elsa , Walport Mark J. , Langhorne Jean , Botto Marina 
Published: July 2002

ABSTRACTWe have studied the impact of deficiency of the complement system on the progression and control of the erythrocyte stages of the malarial parasitePlasmodium chabaudi chabaudi. C1q-deficient mice and factor B- and C2-deficient mice, deficient in the classical complement pathway and in both the alternative and classical complement activation pathways, respectively, exhibited only a slight delay in the resolution of the acute phase of parasitemia. Complement-deficient mice showed a transiently elevated level of gamma interferon (IFN-γ) in the plasma at the time of the acute parasitemia compared with that of wild-type mice. Although there was a trend for increased precursor frequencies in CD4+T cells from C1q-deficient mice producing IFN-γ in response to malarial antigens in vitro, intracellular cytokine staining of spleen cells ex vivo showed no difference in the numbers of IFN-γ+splenic CD4+and CD8+cells. In contrast, C1q-deficient animals were significantly more susceptible to a second challenge with the same parasite. C1q-deficient animals showed a reduced level of anti-malarial immunoglobulin G2a (IgG2a) antibody 100 days after primary infection. However, following a significantly higher parasitemia, C1q-deficient mice had increased levels of IgM and IgG2a anti-malarial antibodies. In summary, this study indicates that while complement plays only a minor role in the control of the acute phase of parasitemia of a primary infection, it does contribute to parasite control in reinfection.
Deficiency of
d
-Erythroascorbic Acid Attenuates Hyphal Growth and Virulence of
Candida albicans
Authors: Huh Won-Ki , Kim Seong-Tae , Kim Hyungsoo , Jeong Gajin , Kang Sa-Ouk 
Published: July 2002

ABSTRACT

In some lower eukaryotes,
d
-erythroascorbic acid, a five-carbon analog of
l
-ascorbic acid, is present instead of
l
-ascorbic acid. We have cloned
ALO1
, the gene encoding
d
-arabinono-1,4-lactone oxidase, which catalyzes the final step of
d
-erythroascorbic acid biosynthesis in
Candida albicans
. The
ALO1
gene contained a continuous open reading frame of 1,671 bp that encodes a polypeptide consisting of 557 amino acids with a calculated molecular mass of 63,428 Da. To investigate the functional roles of
d
-erythroascorbic acid in
C. albicans
, we disrupted or overexpressed the
ALO1
gene. In the
alo1/alo1
null mutants, the activity of
d
-arabinono-1,4-lactone oxidase was completely lost and
d
-erythroascorbic acid could not be detected. When
ALO1
on a multicopy plasmid was transformed in
C. albicans
, the enzyme activity and the intracellular
d
-erythroascorbic acid level were increased up to 3.4-fold and 4.0-fold, respectively. The
alo1/alo1
null mutants of
C. albicans
showed increased sensitivity towards oxidative stress. Overexpression of
ALO1
made the cells more resistant to the same stress. The
alo1/alo1
mutants showed defective hyphal growth and attenuated virulence. Taken together, our results suggest that
d
-erythroascorbic acid functions as an important antioxidant and can be considered one of the virulence factors enhancing the pathogenicity of
C. albicans
.
Stress-Induced ClpP Serine Protease ofListeria monocytogenesIs Essential for Induction of Listeriolysin O-Dependent Protective Immunity
Authors: Gaillot Olivier , Bregenholt Søren , Jaubert Francis , Di Santo James P. , Berche Patrick 
Published: July 2002

ABSTRACTThe stress-induced protease ClpP is required for virulence of the facultative intracellular pathogenListeria monocytogenes. We previously found that in the absence of ClpP, the virulence of this pathogen was strongly reduced, mainly due to the decreased production of functional listeriolysin O (LLO), a major immunodominant virulence factor promoting intracellular growth. In this work, aclpPdeletion mutant ofL. monocytogeneswas used to study the generation of anti-Listeriaprotective immunity. We found that ClpP is required for the intracellular growth ofL. monocytogenesin resident macrophages in vivo. Mice infected with doses as high as 106clpPmutant bacteria were not protected against a lethal challenge of wild-type bacteria and did not develop any detectable LLO-specific cytolytic T cells or antibodies, suggesting that the amount of LLO produced in infected mice under these conditions was too low to induce a specific immune response. However, in contrast to the results obtained with a mutant with a disruptedhlygene, this lack of protection was overcome by inoculation of very high infecting doses ofclpPmutant bacteria (5 × 108), thus producing sufficient amounts of LLO to stimulate anti-Listeriaimmunity. The role of ClpP was confirmed by showing that anti-Listeriaimmunity was restored in mice infected with aclpP-complemented mutant. These results indicate that the stress-induced serine protease ClpP is a potential target for modulating the presentation of protective antigens such as LLO and thereby the immune response againstL. monocytogenes.
Independent and Coordinate Effects of ADP-Ribosyltransferase and GTPase-Activating Activities of Exoenzyme S on HT-29 Epithelial Cell Function
Authors: Fraylick Jennifer E. , La Rocque Jeannine R. , Vincent Timothy S. , Olson Joan C. 
Published: July 2002

ABSTRACT

Type III-mediated translocation of exoenzyme S (ExoS) into HT-29 epithelial cells by
Pseudomonas aeruginosa
causes complex alterations in cell function, including inhibition of DNA synthesis, altered cytoskeletal structure, loss of readherence, microvillus effacement, and interruption of signal transduction. ExoS is a bifunctional protein having both GTPase-activating (GAP) and ADP-ribosyltransferase (ADPRT) functional domains. Comparisons of alterations in HT-29 cell function caused by
P. aeruginosa
strains that translocate ExoS having GAP or ADPRT mutations allowed the independent and coordinate functions of the two activities to be assessed. An E381A ADPRT mutation revealed that ExoS ADPRT activity was required for effects of ExoS on DNA synthesis and long-term cell rounding. Conversely, the R146A GAP mutation appeared to have little impact on the cellular effects of ExoS. While transient cell rounding was detected following exposure to the E381A mutant, this rounding was eliminated by an E379A-E381A ADPRT double mutation, implying that residual ADPRT activity, rather than GAP activity, was effecting transient cell rounding by the E381A mutant. To explore this possibility, E381A and R146A-E381A mutants were examined for their ability to ADP-ribosylate Ras in vitro or in vivo. While no ADP-ribosylation of Ras was detected by either mutant in vitro, both mutants were able to modify Ras when translocated by the bacteria, with the R146A-E381A mutant causing more efficient modification than the E381A mutant, in association with increased inhibition of DNA synthesis. Comparisons of Ras ADP-ribosylation by wild-type and E381A mutant ExoS by two-dimensional electrophoresis found the former to ADP-ribosylate Ras at two sites, while the latter modified Ras only once. These studies draw attention to the key role of ExoS ADPRT activity in causing the effects of bacterially translocated ExoS on DNA synthesis and cell rounding. In addition, the studies provide insight into the enhancement of ExoS ADPRT activity within the eukaryotic cell microenvironment and into possible modulatory roles that the GAP and ADPRT domains might have on the function of each other.
Adherent Invasive
Escherichia coli
Strains from Patients with Crohn's Disease Survive and Replicate within Macrophages without Inducing Host Cell Death
Authors: Glasser Anne-Lise , Boudeau Jerome , Barnich Nicolas , Perruchot Marie-Helene , Colombel Jean-Frederic , Darfeuille-Michaud Arlette 
Published: July 2002

ABSTRACT

Escherichia coli
strains recovered from Crohn's disease (CD) lesions are able to adhere to and invade cultured intestinal epithelial cells. We analyzed the behavior within macrophages of adherent invasive
E. coli
(AIEC) strains isolated from patients with CD. All the 15 AIEC strains tested were able to replicate extensively within J774-A1 cells: the numbers of intracellular bacteria increased 2.2- to 74.2-fold at 48 h over that at 1 h postinfection. By use of murine peritoneal macrophages and human monocyte-derived-macrophages, the reference AIEC strain LF82 was confirmed to be able to survive intracellularly. Transmission electron micrographs of AIEC LF82-infected macrophages showed that at 24 h postinfection, infected cells harbored large vacuoles containing numerous bacteria, as a result of the fusion of several vacuoles occurring after 8 h postinfection. No lactate dehydrogenase (LDH) release, no sign of DNA fragmentation or degradation, and no binding to fluorescein isothlocyanate-labeled annexin V were observed with LF82-infected J774-A1 cells, even after 24 h postinfection. LF82-infected J774-A1 cells secreted 2.7-fold more tumor necrosis factor alpha (TNF-α) than cells stimulated with 1 μg of lipopolysaccharide (LPS)/ml. No release of interleukin-1β was observed with LPS-prestimulated J774-A1 cells infected with AIEC LF82. These findings showed that (i) AIEC strains are able to survive and to replicate within macrophages, (ii) AIEC LF82 replication does not induce any cell death of the infected cells, and (iii) LF82-infected J774-A1 cells release high levels of TNF-α. These properties could be related to some features of CD and particularly to granuloma formation, one of the hallmarks of CD lesions.