bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytokine Involvement in Immunomodulatory Activity Affected byCandida albicansMannan
Authors: Wang Yanyun , Li Shaokang P. , Moser Stephen A. , Bost Kenneth L. , Domer Judith E. 
Published: December 2019

ABSTRACTCandida albicansmannoprotein (MAN) administered intravenously to mice stimulates the production of splenic CD8+effector cells which downregulate delayed hypersensitivity (DH) in immunized mice. Cytokine involvement in the induction and/or elicitation of downregulation was studied by (i) examining murine splenocytes qualitatively for mRNA for interleukin-2 (IL-2), IL-4, IL-10, IL-12p40, and gamma interferon (IFN-γ), (ii) quantitating splenocyte mRNA for IL-12p40 by quantitative-competitive reverse transcriptase-mediated PCR, and (iii) measuring serum levels of IL-12p40 and IL-12p70 by capture enzyme-linked immunosorbent assay, each performed at selected intervals over 96 h after giving MAN. Further, the effect of in vivo administration of anti-IL-4 on the induction and elicitation of MAN-specific DH in MAN-treated mice was measured. Expression of IL-12p40 mRNA in the spleen was reduced to near 0 during the first 24 h but rebounded thereafter. Transcripts for IL-10 were present throughout the 96-h period, whereas those for IL-4 and IFN-γ were either weak or undetectable prior to 24 to 48 h. In vivo administration of anti-IL-4 partially abrogated the downregulatory effect of MAN only when given at the time of MAN administration. Serum levels of IL-12p40, but not IL-12p70, were increased by 24 h and maximal at 48 h. The antagonistic effect of IL-12p40 could contribute to the mechanism(s) for downregulation of DH. Moreover, IL-10, IL-4, and/or IFN-γ, interacting with MAN-activated cells in the absence of biologically active IL-12, may induce the production of CD8+downregulatory effector cells. Partial abrogation of downregulatory activity in animals treated with anti-IL-4 at the time of induction of such activity lends support to this hypothesis.
Mutation of
invH
, but Not
stn
, Reduces
Salmonella
-Induced Enteritis in Cattle
Authors: Watson Patricia R. , Galyov Edouard E. , Paulin Sue M. , Jones Philip W. , Wallis Tim S. 
Published: December 2019

ABSTRACT

The induction of secretory and inflammatory responses in calves by
Salmonella typhimurium
and
Salmonella dublin
strains was compared, and the effects of mutations in the
invH
and
stn
genes were assessed.
S. typhimurium
induced greater secretory and inflammatory responses than
S. dublin
in bovine ileal loops, despite the fact that these serotypes were recovered from bovine ileal mucosa in comparable numbers (P. R. Watson, S. M. Paulin, A. P. Bland, P. W. Jones, and T. S. Wallis, Infect. Immun. 63:2743–2754, 1995). These results implicate serotype-specific factors other than, or in addition to, intestinal invasion in the induction of enteritis. The secretory and inflammatory responses induced by
S. typhimurium
and
S. dublin
in bovine ligated ileal loops were not significantly altered by mutation of
stn
, which suggests that
stn
does not have a major role in
Salmonella
-induced enteritis. The
invH
mutation significantly reduced the secretory and inflammatory responses induced in bovine ileal loops, and this correlated with a reduction in the severity of enteritis following oral inoculation of calves. The attenuation associated with the
invH
mutation did not appear to be due to an increased susceptibility to the innate host defense mechanisms, because the resistance of
S. typhimurium
to the bactericidal action of either bovine polymorphonuclear leukocytes or bovine serum was not significantly altered. However, lysis of macrophages following infection with
S. typhimurium
was significantly reduced by the
invH
mutation. The
invH
mutation prevented the normal secretion of several proteins, including SipC, by
S. typhimurium
, indicating that the function of the
inv-spa
-encoded type III protein secretion system was disrupted. Taken together, these observations implicate
inv-spa
-dependent effectors in mediation of
Salmonella
-induced enteritis in cattle. Clearly, however, other undefined serotype-specific virulence factors are also involved in
Salmonella
-induced enteritis.
Pseudomonas aeruginosa
Invasion and Cytotoxicity Are Independent Events, Both of Which Involve Protein Tyrosine Kinase Activity
Authors: Evans David J. , Frank Dara W. , Finck-Barbançon Viviane , Wu Christine , Fleiszig Suzanne M. J. 
Published: December 2019

ABSTRACT

Pseudomonas aeruginosa
clinical isolates exhibit invasive or cytotoxic phenotypes. Cytotoxic strains acquire some of the characteristics of invasive strains when a regulatory gene,
exsA
, that controls the expression of several extracellular proteins, is inactivated.
exsA
mutants are not cytotoxic and can be detected within epithelial cells by gentamicin survival assays. The purpose of this study was to determine whether epithelial cell invasion precedes and/or is essential for cytotoxicity. This was tested by measuring invasion (gentamicin survival) and cytotoxicity (trypan blue staining) of PA103 mutants deficient in specific
exsA
-regulated proteins and by testing the effect of drugs that inhibit invasion for their effect on cytotoxicity. A transposon mutant in the
exsA
-regulated extracellular factor
exoU
was neither cytotoxic nor invasive. Furthermore, several of the drugs that inhibited invasion did not prevent cytotoxicity. These results show that invasion and cytotoxicity are mutually exclusive events, inversely regulated by an
exsA
-encoded invasion inhibitor(s). Both involve host cell protein tyrosine kinase (PTK) activity, but they differ in that invasion requires Src family tyrosine kinases and calcium-calmodulin activity. PTK inhibitor drugs such as genistein may have therapeutic potential through their ability to block both invasive and cytotoxicity pathways via an action on the host cell.
Role of Intimin and Bundle-Forming Pili in Enteropathogenic
Escherichia coli
Adhesion to Pediatric Intestinal Tissue In Vitro
Authors: Hicks Susan , Frankel Gad , Kaper James B. , Dougan Gordon , Phillips Alan D. 
Published: December 2019

ABSTRACT

Attaching and effacing (A/E) lesion formation is central to enteropathogenic
Escherichia coli
(EPEC) pathogenesis. In vitro experiments with human epithelial cell lines have implicated virulence plasmid-encoded bundle-forming pili (BFP) in initial binding and intimin in intimate attachment and A/E lesion formation. This study investigated the role of BFP and intimin in EPEC interactions with pediatric small intestinal biopsy tissue in in vitro organ culture. Organ culture infections (2 to 8 h) were performed with E2348/69 (a wild-type EPEC O127:H6 clinical isolate) and E2348/69 derivatives including CVD206 (
eae
deficient), CVD206(pCVD438) (
eae
-complemented CVD206), CVD206(pCVD438/01) (expressing intimin, which is nonfunctional due to a single amino acid substitution), JPN15 (spontaneous EPEC adherence factor virulence plasmid-cured E2348/69), and 31-6-1(1) (E2348/69 with a Tn
phoA
insertion inactivation mutation in the virulence plasmid-encoded
bfpA
gene). Scanning and transmission electron microscopy revealed that after 8 h E2348/69 and CVD206(pCVD438) (both Int
+
BFP
+
) adhered to all specimens, causing A/E lesions with surrounding microvillous elongation. JPN15 and 31-6-1(1) (both Int
+
BFP
−
) adhered and caused A/E lesions although bacteria adhered in “flat,” two-dimensional groups. CVD206 and CVD206(pCVD438/01) (both Int
−
BFP
+
) did not adhere to any sample, and no pathological tissue changes were seen. Thus, in human intestinal organ culture, BFP do not appear to be involved in the initial stages of EPEC nonintimate adhesion but are implicated in the formation of complex, three-dimensional colonies via bacterium-bacterium interactions. Intimin appears to play an essential role in establishing colonization of EPEC on pediatric small intestinal tissue.
Phagocytosis of the Malarial Pigment, Hemozoin, Impairs Expression of Major Histocompatibility Complex Class II Antigen, CD54, and CD11c in Human Monocytes
Authors: Schwarzer Evelin , Alessio Massimo , Ulliers Daniela , Arese Paolo 
Published: December 2019

ABSTRACTInPlasmodium falciparummalaria, large proportions of resident macrophages and circulating monocytes and leukocytes contain massive amounts of the malarial pigment, hemozoin. Previous studies have shown that important functions (e.g., the generation of the oxidative burst, the ability to repeat phagocytosis, and protein kinase C activity) were severely impaired in hemozoin-loaded monocytes. Expression of membrane antigens directly involved in the immune response and in the phagocytic process, and/or under protein kinase C control, in hemozoin-loaded human monocytes was studied. Expression of major histocompatibility complex (MHC) class II after gamma interferon stimulation was blocked in hemozoin-loaded monocytes at the protein expression and gene transcription levels but was preserved in control monocytes loaded with opsonized latex beads or anti-D(Rho)-immunoglobulin G (IgG)-opsonized human erythrocytes. Expression of CD54 (intracellular adhesion molecule 1) and CD11c (p150,95 integrin) was also decreased in hemozoin-loaded monocytes. Expression of MHC class I, CD16 (low-affinity Fc receptor for aggregated IgG), CD32 (low-affinity Fc receptor for aggregated IgG), CD64 (high-affinity receptor for IgG), CD11b (receptor for complement component iC3b [CR3]), CD35 (receptor for complement components C3b and C4b [CR1]), and CD36 (non-class-A scavenger receptor) was not specifically affected by hemozoin loading. These results suggest that hemozoin loading may contribute to the impairment of the immune response and the derangement of antigen presentation reported in previous studies ofP. falciparummalaria.
Divergent Signal Transduction Responses to Infection with Attaching and Effacing
Escherichia coli
Authors: Ismaili Arif , McWhirter Elaine , Handelsman Michelle Y. C. , Brunton James L. , Sherman Philip M. 
Published: December 2019

ABSTRACT

Shiga toxin-producing
Escherichia coli
(STEC) O157:H7 is an attaching and effacing pathogen that causes hemorrhagic colitis and the hemolytic-uremic syndrome. Although this organism causes adhesion pedestals, the cellular signals responsible for the formation of these lesions have not been clearly defined. We have shown previously that STEC O157:H7 does not induce detectable tyrosine phosphorylation of host cell proteins upon binding to eukaryotic cells and is not internalized into nonphagocytic epithelial cells. In the present study, tyrosine-phosphorylated proteins were detected under adherent STEC O157:H7 when coincubated with the non-intimately adhering, intimin-deficient, enteropathogenic
E. coli
(EPEC) strain CVD206. The ability to be internalized into epithelial cells was also conferred on STEC O157:H7 when coincubated with CVD206 ([158 ± 21] % of control). Neither the ability to rearrange phosphotyrosine proteins nor that to be internalized into epithelial cells was evident following coincubation with another STEC O157:H7 strain or with the nonsignaling
espB
mutant of EPEC.
E. coli
JM101(pMH34/pSSS1C), which overproduces surface-localized O157 intimin, also rearranged tyrosine-phosphorylated and cytoskeletal proteins when coincubated with CVD206. In contrast, JM101(pMH34/pSSS1C) demonstrated rearrangement of cytoskeletal proteins, but not tyrosine-phosphorylated proteins, when coincubated with intimin-deficient STEC (strains CL8KO1 and CL15). These findings indicate that STEC O157:H7 forms adhesion pedestals by mechanisms that are distinct from those in attaching and effacing EPEC. Taken together, these findings point to diverging signal transduction responses to infection with attaching and effacing bacterial enteropathogens.
Enhancement of Lipopolysaccharide-Induced Neutrophil Oxygen Radical Production by Tumor Necrosis Factor Alpha
Authors: Jersmann Hubertus P. A. , Rathjen Deborah A. , Ferrante Antonio 
Published: December 2019

ABSTRACTAlthough tissues become exposed to both exogenous and endogenous cell-activating mediators during infection, there is little appreciation of the effects of subjecting cells to multiple mediators. We examined the hypothesis that the response of neutrophils to bacterial lipopolysaccharide (LPS) is significantly altered in the presence of the endogenous mediator tumor necrosis factor alpha (TNF). The data showed that human neutrophils pretreated with TNF for 10 to 30 min, displayed significantly enhanced superoxide production in response to LPS (from eitherEscherichia coliK-235 orE. coli0127:B8), measured as lucigenin-dependent chemiluminescence (CL), seen as an increase in the initial peak rate as well as the total CL accumulated over the incubation period. TNF amplified the response to LPS at 1 to 100 U of TNF/106neutrophils and was able to enhance the response to a wide range of concentrations of LPS (0.01 to 1,000 ng/ml). The TNF-induced increase in the LPS response was paralleled by an increase in LPS binding to the neutrophils, which could be abrogated by an anti-CD14 monoclonal antibody. The results demonstrate that TNF significantly increases the LPS-induced release of oxygen radicals in neutrophils through the upregulation of cell surface CD14.
Adherence to and Penetration of Human Intestinal Caco-2 Epithelial Cell Monolayers by
Pseudomonas aeruginosa
Authors: Hirakata Yoichi , Izumikawa Kohichi , Yamaguchi Toshiyuki , Igimi Shizunobu , Furuya Nobuhiko , Maesaki Shigefumi , Tomono Kazunori , Yamada Yasuaki , Kohno Shigeru , Yamaguchi Keizo , Kamihira Shimeru 
Published: December 2019

ABSTRACT

Clinical isolates of
Pseudomonas aeruginosa
from blood adhered to and penetrated intestinal Caco-2 cell monolayers to a greater degree than did isolates from sputum, with a concomitant drastic decrease in transepithelial electrical resistance. PAO-PR1, an avirulent exotoxin A mutant of PAO1, did not cause a decrease in the resistance. The Caco-2 monolayer system may be useful for the evaluation of certain
P. aeruginosa
virulence factor activities.
Expression of the
Candida albicans
Gene
ALS1
in
Saccharomyces cerevisiae
Induces Adherence to Endothelial and Epithelial Cells
Authors: Fu Yue , Rieg Günter , Fonzi William A. , Belanger Paul H. , Edwards John E. , Filler Scott G. 
Published: December 2019

ABSTRACT

To identify genes encoding adhesins that mediate the binding of
Candida albicans
to endothelial cells, a genomic library from this organism was constructed and used to transform
Saccharomyces cerevisiae
. These transformed organisms were screened for adherence to endothelial cells, and a highly adherent clone was identified. The adherence of this clone to endothelial cells was over 100-fold greater than that of control
S. cerevisiae
transformed with the empty plasmid. This clone also exhibited enhanced adherence to epithelial cells. The
C. albicans
gene contained within this clone was found to be
ALS1
. These results indicate that
ALS1
may encode a candidal adhesin.
Hemoglobin-Induced Binding of
Candida albicans
to the Cell-Binding Domain of Fibronectin Is Independent of the Arg-Gly-Asp Sequence
Authors: Yan Sizhuang , Rodrigues Rui G. , Roberts David D. 
Published: December 2019

ABSTRACT

Hemoglobin specifically induces fibronectin (FN) binding to the pathogenic yeast
Candida albicans
. When grown in the complex medium Sabouraud broth,
C. albicans
expresses receptors that bind to several domains of FN. Growth in defined medium supplemented with 0.1% hemoglobin, however, enhanced the binding of FN to a single class of receptors, with a

K
d

= 4.6 × 10
−8
M. Competitive binding assays using recombinant and proteolytic fragments of FN revealed that the cell-binding domain mediated this interaction. A recombinant 40-kDa fragment of FN consisting of type III repeats 9 to 13 had an inhibitory activity similar to that of the entire 120-kDa cell-binding domain, indicating that the C-terminal portion of the cell-binding domain contains the binding site. A recombinant 33-kDa fragment of the cell-binding domain and a 33-kDa fragment with the RGD sequence deleted had the same inhibitory activities, demonstrating that the RGD sequence recognized by some mammalian integrins is not required. The addition of hemoglobin to the culture medium also enhanced
Candida
cell adhesion to immobilized FN and to 120- and 40-kDa fragments of FN but not to the collagen-binding or fibrin I domains. Using ligand protection, we identified a surface protein from
C. albicans
with an apparent molecular mass of 55 kDa that was protected by both FN and the 40-kDa fragment derived from the cell-binding domain. Therefore, hemoglobin both induces FN binding and changes the relative affinities of
C. albicans
for the cell- and collagen-binding domains of FN.
Comparisons between Colony Phase Variation of
Neisseria gonorrhoeae
FA1090 and Pilus, Pilin, and S-Pilin Expression
Authors: Long Cynthia D. , Madraswala Rashida N. , Seifert H. Steven 
Published: December 2019

ABSTRACT

The gonococcal pilus is a primary virulence factor, providing the initial attachment of the bacterial cell to human mucosal tissues. Pilin, the major subunit of the pilus, can carry a wide spectrum of primary amino acid sequences which are generated by the action of a complex antigenic variation system. Changes in the pilin amino acid sequence can produce different pilus-dependent colony morphotypes, which have been previously shown to reflect phase variation of pili on the bacterial cell surface. In this study, we further examined the relationships between changes in pilus-dependent colony morphology, pilin sequence, pilus expression, and pilus function in
Neisseria gonorrhoeae
FA1090. A group of FA1090 colony variants expressed different pilin sequences and demonstrated different levels of pilin, S-pilin, and pilus expression. The analysis of these colony variants shows that they do not represent two distinct phases of pilus expression, but that changes in pilin protein sequence produce a spectrum of S-pilin production, pilus expression, and pilus aggregation levels. These different levels of pilus expression and aggregation influence not only colony morphology but also DNA transformation efficiency and epithelial cell adherence.
Participation of Parasite Surface Glycoproteins in Antibody-Mediated Protection of Epithelial Cells against
Trichinella spiralis
Authors: McVay Catherine S. , Tsung Allan , Appleton Judith 
Published: December 2019

ABSTRACT

The L1 stage of the parasitic nematode
Trichinella spiralis
displays on its surface glycoproteins that are immunologically cross-reactive with several larval excretory-secretory (ES) products. The basis for the cross-reactivity is tyvelose, the terminal residue on the complex glycans shared by these surface and ES glycoproteins. In neonatal rats, tyvelose-specific monoclonal antibodies mediate the expulsion of larvae from the intestine. The aim of the studies described in this report was to determine how antibody binding to larval surfaces contributes to expulsion. In these experiments, which involve an in vitro assay of epithelial cell invasion, surface proteins on living larvae were biotinylated to distinguish them from ES products. Biotinylated and nonbiotinylated larvae were cocultured with avidin, biotin-specific antibodies, or anti-tyvelose monoclonal antibodies. Biotinylated larvae cultured with avidin or biotin-specific antibodies invaded Madin-Darby canine kidney (MDCK) cells equally as well as biotinylated larvae cultured with medium alone. Anti-tyvelose monoclonal antibodies were highly protective in this assay; however, biotinylation of larval surfaces hindered the ability of anti-tyvelose monoclonal antibodies to prevent larval invasion of epithelial cells. This correlated with a reduction in the binding of anti-tyvelose antibody to biotinylated larval surfaces. Our results indicate that antibody binding to surface glycoproteins contributes to protection against
T. spiralis
invasion but that surface binding alone is not sufficient for protection. Our findings support the notion that protection is effected by cross-linking of ES products to surface antigens.
The Cell Wall-Associated Glyceraldehyde-3-Phosphate Dehydrogenase of
Candida albicans
Is Also a Fibronectin and Laminin Binding Protein
Authors: Gozalbo Daniel , Gil-Navarro Inés , Azorín Inmaculada , Renau-Piqueras Jaime , Martínez José P. , Gil M. Luisa 
Published: December 2019

ABSTRACT

By immunoelectron microscopy with a polyclonal antibody against the cytosolic glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from
Candida albicans
(anti-GAPDH PAb), the protein was clearly detected at the outer surface of the cell wall, particularly on blastoconidia, as well as in the cytoplasm. Intact blastoconidia were able to adhere to fibronectin and laminin immobilized on microtiter plates, and this adhesion was markedly reduced by both the anti-GAPDH PAb and soluble GAPDH from
Saccharomyces cerevisiae
. In addition, semiquantitative flow cytometry analysis with the anti-GAPDH PAb showed a decrease in antibody binding to cells in the presence of soluble fibronectin and laminin. Purified cytosolic
C. albicans
GAPDH was found to bind to fibronectin and laminin in a ligand Western blot assay. These observations suggest that the cell wall-associated form of the GAPDH in
C. albicans
could be involved in mediating adhesion of fungal cells to fibronectin and laminin, thus contributing to the attachment of the microorganism to host tissues and to the dissemination of
Candida
infection.
Nitric Oxide is Produced byCowdria ruminantium-Infected Bovine Pulmonary Endothelial Cells In Vitro and Is Stimulated by Gamma Interferon
Authors: Mutunga Mbithe , Preston Patricia M. , Sumption Keith J. 
Published: December 2019

ABSTRACTNitric oxide (NO) is a labile inorganic free radical produced by NO synthase from the substratel-arginine in various cells and tissues including endothelial cells. A substantial elevation of nitrite levels indicative of NO production occurred in cultures ofCowdria ruminantium-infected bovine pulmonary endothelial cells (BPEC) incubated in medium alone. Exposure of the infected cultures to recombinant bovine gamma interferon (BorIFN-γ) resulted in more rapid production of NO, reduced viability ofC. ruminantium, and induction of endothelial cell death. Significant inhibition of NO production was noted after addition of the NO synthase inhibitorN-monomethyl-l-arginine (l-NMMA), indicating that the increase in production occurred via the inducible NO synthase pathway. Reduction in the infectivity ofC. ruminantiumelementary bodies (EBs) occurred in a dose-dependent manner after incubation with the NO donor moleculeS-nitroso-N-acetyl-dl-penicillamine (SNAP) prior to infection of endothelial cells. The level of infection in cultures maintained in SNAP was reduced in a dose-dependent manner with significant negative correlation between the final level of infection on day 7 and the level of SNAP (r= −0.96). It was established that pretreatment and cultivation ofC. ruminantiumEBs with the NO donor molecule SNAP reduced infectivity to cultures and viability of EBs with the implication that release of NO in vivo following infection of endothelial cells may have an effect upon the multiplication of the agent in the host animal and may be involved in the pathogenesis of heartwater through the effect of this molecule upon circulation.