bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Cysteine-Cysteine Family of Chemokines RANTES, MIP-1α, and MIP-1β Induce Trypanocidal Activity in Human Macrophages via Nitric Oxide
Authors: Villalta Fernando , Zhang Yuan , Bibb Kartz E. , Kappes John C. , Lima Maria F. 
Published: December 2019

ABSTRACTThis paper describes a new role for the cysteine-cysteine (CC) chemokines RANTES, MIP-1α, and MIP-1β on human macrophage function, which is the induction of nitric oxide (NO)-mediated trypanocidal activity. In a previous report, we showed that RANTES, MIP-1α and MIP-1β enhanceTrypanosoma cruziuptake and promote parasite killing by human macrophages (M. F. Lima, Y. Zhang, and F. Villalta, Cell. Mol. Biol. 43:1067–1076, 1997). Here we study the mechanism by which RANTES, MIP-1α, and MIP-1β activate human macrophages obtained from healthy individuals to killT. cruzi. Treatment of human macrophages with different concentrations of RANTES, MIP-1α, and MIP-1β enhancesT. cruzitrypomastigote phagocytosis in a dose peak response. The optimal response induced by the three CC chemokines is attained at 500 ng/ml. The macrophage trypanocidal activity induced by CC chemokines can be completely inhibited byl-N-monomethyl arginine (l-NMMA), a specific inhibitor of thel-arginine:NO pathway, but not by itsd-enantiomer. Culture supernatants of chemokine-treated human macrophages contain increased NO2−levels, and NO2−production is also specifically inhibited byl-NMMA. The amount of NO2−induced by these chemokines in human macrophages is comparable to the amount of NO2−induced by gamma interferon. The killing of trypomastigotes by NO in cell-free medium is blocked by an NO antagonist or a NO scavenger. This data supports the hypothesis that the CC chemokines RANTES, MIP-1α, and MIP-1β activate human macrophages to killT. cruzivia NO, which is an effective trypanocidal mechanism.
The
ica
Locus of
Staphylococcus epidermidis
Encodes Production of the Capsular Polysaccharide/Adhesin
Authors: McKenney David , Hübner Johannes , Muller Eugene , Wang Ying , Goldmann Donald A. , Pier Gerald B. 
Published: December 2019

ABSTRACT

Clinical isolates of coagulase-negative staphylococci often elaborate a biofilm involved in adherence to medical devices and resistance to host defenses. The biofilm contains the capsular polysaccharide/adhesin (PS/A), which mediates cell adherence to biomaterials, and another antigen, termed polysaccharide intercellular adhesin (PIA), which is thought to mediate bacterial accumulation into cellular aggregates. PIA is a polymer of β-1,6-linked
N
-acetyl glucosamine residues with a molecular mass of <30,000 kDa. We found that recombinant
Staphylococcus carnosus
and
Staphylococcus aureus
carrying a plasmid with genes of the
ica
locus, which was reported to encode the biosynthetic proteins for production of PIA, were also able to synthesize PS/A. PS/A and a chemically and immunologically identical polysaccharide isolated from
S. carnosus
carrying the
ica
genes on plasmid pCN27 were found to be high-molecular-mass (>250,000 kDa), acid-stable polymers of β-1,6-linked glucosamine substituted on the amino group primarily with succinate, although some preparations also contained acetate. Moreover, all recombinant staphylococcal strains with the
ica
genes had the biologic properties previously attributed to PS/A.
ica
-positive strains readily formed an in vitro biofilm on plastic, adhered 3- to 10-fold more to catheters during a 30-min assay compared with control strains carrying only the cloning vector, adsorbed out antibodies to PS/A from immune serum, and elaborated a capsule visualized by immunoelectron microscopy with antisera to PS/A. These properties were also seen with PS/A-producing strains of
Staphylococcus epidermidis
, but not with transposon mutants lacking PS/A. An antiserum raised to PIA contained high-titer antibody to PS/A that was readily adsorbed out by PS/A-positive strains of
S. epidermidis
and recombinant strains of staphylococci carrying the
ica
genes. We conclude that the
ica
locus encodes production of PS/A and that the properties of
S. epidermidis
associated with initial bacterial adherence, biofilm formation, and intercellular adhesion can be correlated with elaboration of PS/A.
Urease Plays an Important Role in the Chemotactic Motility of
Helicobacter pylori
in a Viscous Environment
Authors: Nakamura Hiroki , Yoshiyama Hironori , Takeuchi Hiroaki , Mizote Tomoko , Okita Kiwamu , Nakazawa Teruko 
Published: December 2019

ABSTRACT

Helicobacter pylori
exhibits chemotactic responses to urea, flurofamide, acetohydroxamic acid, and sodium bicarbonate. In buffer, the chemotactic activities of a urease-positive strain were higher than those of the isogenic urease-negative strain. Moreover, the chemotactic activities of the urease-positive strain were increased in a viscous solution containing 3% polyvinylpyrrolidone, whereas those of the urease-negative mutant were not. These results are in accordance with the fact that the mutant strain did not show swarming in motility agar regardless of having flagella. Incubation of the wild-type strain with flurofamide resulted in partial inhibition of the chemotactic activities in the viscous solution. In addition, incubation with acetohydroxamic acid, a low-molecular-weight, diffusible urease inhibitor, resulted in complete loss of chemotactic activity in the viscous solution. The inhibition of the chemotactic activity by urease inhibitors paralleled the inhibition of urease. The chemotactic activity of
H. pylori
was also inhibited by the proton carrier carbonyl cyanide
m
-chlorophenylhydrazone, showing that
H. pylori
utilizes proton motive force for motility. These results indicate that cytoplasmic urease plays an important role in the chemotactic motility of
H. pylori
under a condition that mimics the ecological niche of the bacterium, the gastric mucous layer.
Interleukin-12 Is Essential for a Protective Th1 Response in Mice Infected withCryptococcus neoformans
Authors: Decken Klaus , Köhler Gabriele , Palmer-Lehmann Kathrin , Wunderlin Andrea , Mattner Frank , Magram Jeanne , Gately Maurice K. , Alber Gottfried 
Published: December 2019

ABSTRACTTo analyze the roles of interleukin-12 (IL-12) and the IL-12-dependent Th1 response in resistance toCryptococcus neoformans, we have established a chronic infection model in wild-type mice and in mice with targeted disruptions of the genes for the IL-12p35 and IL-12p40 subunits (IL-12p35−/−and IL-12p40−/−mice, respectively) as well as in mice with a targeted disruption of the IL-4 gene. Long-term application of exogenous IL-12 prevented death of infected wild-type mice for the entire period of the experiment (up to 180 days) but did not resolve the infection. Infected IL-12p35−/−and IL-12p40−/−mice died significantly earlier than infected wild-type mice, whereas infection of IL-4-deficient mice led to prolonged survival. Interestingly, infected IL-12p40−/−mice died earlier and developed higher organ burdens than IL-12p35−/−mice, which, for the first time in an infection model, suggests a protective role of the IL-12p40 subunit independent of the IL-12 heterodimer. The fungal organ burdens of IL-4-deficient mice and IL-12-treated wild-type mice were significantly reduced compared to those of untreated wild-type mice and IL-12-deficient mice. Histopathological analysis revealed reduction of the number of granulomatous lesions following treatment with IL-12. Susceptibility of both IL-12p35−/−and IL-12p40−/−mice was associated with marginal production of gamma interferon and elevated levels of IL-4 from CD4+T cells, which indicates Th2 polarization in the absence of IL-12, whereas wild-type mice developed a Th1 response. Taken together, our data emphasize the essential role of IL-12 for protective Th1 responses againstC. neoformans.
Infection of Epithelial Cells by Pathogenic Neisseriae Reduces the Levels of Multiple Lysosomal Constituents
Authors: Ayala Patricia , Lin Lan , Hopper Sylvia , Fukuda Minoru , So Magdalene 
Published: December 2019

ABSTRACT

Members of our group reported recently that neisseria infection of human epithelial cells results in accelerated degradation of the major lysosomal integral membrane protein LAMP1 and that this is due to hydrolysis of this glycoprotein at its immunoglobulin A1 (IgA1)-like hinge by the neisseria type 2 IgA1 protease (L. Lin et al., Mol. Microbiol. 24:1083–1094, 1997). We also reported that the IgA1 protease plays a major role in the ability of the pathogenic neisseriae to survive within epithelial cells and hypothesized that this is due to alteration of lysosomes as a result of protease-mediated LAMP1 degradation. In this study, we tested the hypothesis that neisseria infection leads to multiple changes in lysosomes. Here, we report that neisseria infection also reduces the levels of three other lysosomal markers: LAMP2, lysosomal acid phosphatase (LAP), and CD63. In contrast, neither the epidermal growth factor receptor level nor the β-tubulin level is affected. A detailed examination of LAMP2 indicated that the reduced LAMP2 levels are not the result of an altered biosynthetic rate or of cleavage by the IgA1 protease. Nevertheless, the protease plays a role in reducing LAMP2 and LAP activity levels, as these are partially restored in cells infected with an
iga
mutant. We conclude that neisseria infection results in multiple changes to the lysosomes of infected epithelial cells and that these changes are likely an indirect result of IgA1 protease-mediated cleavage of LAMP1.
Pathogenicity of an Enterotoxigenic
Escherichia coli
Hemolysin (
hlyA
) Mutant in Gnotobiotic Piglets
Authors: Moxley Rodney A. , Berberov Emil M. , Francis David H. , Xing Jun , Moayeri Mahtab , Welch Rodney A. , Baker Diane R. , Barletta Raúl G. 
Published: December 2019

ABSTRACT

Pigs infected with hemolytic F4
+
strains of enterotoxigenic
Escherichia coli
often develop septicemia secondary to intestinal infection. We tested the hypothesis that inactivation of hemolysin would reduce the ability of F4
+
enterotoxigenic
E. coli
to cause septicemia in swine following oral inoculation. Inactivation of the hemolysin structural gene (
hlyA
) did not decrease the incidence of septicemia in the gnotobiotic piglet model.
Activation of Rho GTPases byEscherichia coliCytotoxic Necrotizing Factor 1 Increases Intestinal Permeability in Caco-2 Cells
Authors: Gerhard Ralf , Schmidt Gudula , Hofmann Fred , Aktories Klaus 
Published: December 2019

ABSTRACTThe cytotoxic necrotizing factor 1 (CNF1) activates Rho GTPases by deamidation of glutamine-63 and thereby induces redistribution of the actin cytoskeleton and formation of stress fibers. Here, we have studied the effects of CNF1 on the transepithelial resistance of Caco-2 cells, a human intestinal epithelial cell line, in comparison with the Rho-inactivating toxin B ofClostridium difficile. Whereas toxin B decreased the transepithelial resistance of Caco-2 cells by about 80% after 4 h, CNF1 reduced it by about 40%. Significant changes of the transepithelial resistance induced by CNF1 were detected after 3 h of incubation. Half-maximal effects were observed with 10 and 41 ng of CNF1 and toxin B per ml, respectively. Flux measurement revealed no CNF1-induced increase of fluorescein isothiocyanate-dextran permeation within the first 4 h of incubation and a 2.9-fold increase after 24 h of incubation. In contrast, toxin B induced a 28-fold increase of permeation after 24 h. As detected by rhodamine-phalloidin staining, CNF1 increased polymerization of F actin at focal contacts of adjacent cells and induced formation of stress fibers. The data indicate that not only depolymerization but also polymerization of actin and subsequent reorganization of the actin cytoskeleton alter the barrier function of intestinal tight junctions.
5-Lipoxygenase Reaction Products Modulate Alveolar Macrophage Phagocytosis ofKlebsiella pneumoniae
Authors: Mancuso Peter , Standiford Theodore J. , Marshall Teresa , Peters-Golden Marc 
Published: December 2019

ABSTRACTThe leukotrienes are potent lipid mediators of inflammation formed by the 5-lipoxygenase-catalyzed oxidation of arachidonic acid. Although the effects of leukotrienes on neutrophil chemotaxis and activation have been established, their role in modulating innate host defense mechanisms is poorly understood. In a previous study (M. Bailie, T. Standiford, L. Laichalk, M. Coffey, R. Strieter, and M. Peters-Golden, J. Immunol. 157:5221–5224, 1996), we used 5-lipoxygenase knockout mice to establish a critical role for endogenous leukotrienes in pulmonary clearance and alveolar macrophage phagocytosis ofKlebsiella pneumoniae. In the present study, we investigated the role of specific endogenous leukotrienes in phagocytosis ofK. pneumoniaeand explored the possibility that exogenous leukotrienes could restore phagocytosis in alveolar macrophages with endogenous leukotriene synthesis inhibition and enhance this process in leukotriene-competent cells. Rat alveolar macrophages produced leukotriene B4(LTB4), LTC4, and 5-hydoxyeicosatetraenoic acid (5-HETE) during the process of phagocytosis, and the inhibition of endogenous leukotriene synthesis with zileuton and MK-886 dramatically attenuated phagocytosis. We also observed a reduction in phagocytosis when we treated alveolar macrophages with antagonists to the plasma membrane receptors for either LTB4, cysteinyl-leukotrienes, or both. In leukotriene-competent cells, LTC4augmented phagocytosis to the greatest extent, followed by 5-HETE and LTB4. These 5-lipoxygenase reaction products demonstrated similar relative abilities to reconstitute phagocytosis in zileuton-treated rat alveolar macrophages and in alveolar macrophages from 5-lipoxygenase knockout mice. We conclude that endogenous synthesis of all major 5-lipoxygenase reaction products plays an essential role in phagocytosis. The restorative and pharmacologic effects of LTC4, LTB4, and 5-HETE may provide a basis for their exogenous administration as an adjunctive treatment for patients with gram-negative bacterial pneumonia.
Role of Liver NK Cells and Peritoneal Macrophages in Gamma Interferon and Interleukin-10 Production in Experimental Bacterial Peritonitis in Mice
Authors: Seki Shuhji , Osada Shun-ichi , Ono Satoshi , Aosasa Suefumi , Habu Yoshiko , Nishikage Tetsuro , Mochizuki Hidetaka , Hiraide Hoshio 
Published: December 2019

ABSTRACTGamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin-10 (IL-10) production by liver, spleen, lung, peripheral blood mononuclear cells (MNC), and peritoneal exudate cells (PEC) in experimental bacterial peritonitis was examined by cecum ligation and puncture (CLP) (with an 18-gauge needle) of BALB/c mice. MNC of organs were cultured for 18 h, and cytokine levels in supernatants were examined. Cytokines contained in peritoneal lavage fluid were regarded as those produced by PEC. Only liver MNC and PEC produced substantial amounts of IFN-γ, and PEC were the main source of IL-10, especially 12 h after CLP. As reflected by the cytokine production by liver MNC and PEC, serum IFN-γ and IL-10 levels were elevated after CLP. C57BL/6 (B6) mice and BALB/c nude mice showed a similar pattern of cytokine production. TNF-α levels in culture supernatants, peritoneal lavage fluid, and sera were not significantly elevated compared to those of sham-operated mice. In vivo depletion of NK cells of B6 mice with anti-asialo GM1 or anti-NK1.1 antibody greatly decreased IFN-γ levels in liver MNC culture supernatants and sera, suggesting that liver NK cells are IFN-γ producers. On the other hand, plastic-adherent PEC macrophages are the major IL-10 producers. Mice subjected to a cecum ligation and cut procedure (which have a more severe peritonitis) showed much higher IFN-γ and IL-10 levels than those subjected to CLP, while mice subjected to CLP with a smaller (22-gauge) needle showed low levels of these cytokines. These findings show that liver NK cells and PEC macrophages are important for the production of proinflammatory and anti-inflammatory cytokines in bacterial peritonitis.
Altered Expression of Selectable Marker
URA3
in Gene-Disrupted
Candida albicans
Strains Complicates Interpretation of Virulence Studies
Authors: Lay Jennifer , Henry L. Keith , Clifford Julie , Koltin Yigal , Bulawa Christine E. , Becker Jeffrey M. 
Published: December 2019

ABSTRACT

The ura-blaster technique for the disruption of
Candida albicans
genes has been employed in a number of studies to identify possible genes encoding virulence factors of this fungal pathogen. In this study, the
URA3
-encoded orotidine 5′-monophosphate (OMP) decarboxylase enzyme activities of
C. albicans
strains with ura-blaster-mediated genetic disruptions were measured. All strains harboring genetic lesions via the ura-blaster construct showed reduced OMP decarboxylase activities compared to that of the wild type when assayed. The activity levels in different gene disruptions varied, suggesting a positional effect on the level of gene expression. Because the
URA3
gene of
C. albicans
has previously been identified as a virulence factor for this microorganism, our results suggest that decreased virulence observed in strains constructed with the ura-blaster cassette cannot accurately be attributed, in all cases, to the targeted genetic disruption. Although revised methods for validating a
URA3
-disrupted gene as a target for antifungal drug development could be devised, it is clearly desirable to replace
URA3
with a different selectable marker that does not influence virulence.
Pathways for Potentiation of Immunogenicity during Adjuvant-Assisted Immunizations withPlasmodium falciparumMajor Merozoite Surface Protein 1
Authors: Hui George S. N. , Hashimoto Caryn N. 
Published: December 2019

ABSTRACTVaccine adjuvants exert critical and unique influences on the quality of immune responses induced during active immunizations. We investigated the mechanisms of action of immunological adjuvants in terms of their requirements for cytokine-mediated pathways for adjuvanticity. Antibody responses potentiated by several adjuvants to aPlasmodium falciparumMSP1-19 (C-terminal 19-kDa processing fragment of MSP1) vaccine were studied in gamma interferon (IFN-γ) or interleukin (IL-4) knockout mice. The levels of anti-MSP1-19 antibodies and the induction of Th1- and Th2-type antibodies were analyzed. Results revealed a spectrum of requirements for cytokine-mediated pathways in the potentiation of immunogenicity, and such requirements were influenced by interactions among individual components of the adjuvant formulations. One adjuvant strictly depended on IFN-γ to induce appreciable levels of anti-MSP1-19 antibodies, while some formulations required IFN-γ only for the induction of Th1-type antibodies. Other formulations induced exclusively Th2-type antibodies and were not affected by IFN-γ knockout. There were three patterns of requirements for IL-4 by various adjuvants in the induction of Th2-type anti-MSP1-19 antibodies. Moreover, the induction of Th1-type anti-MSP1-19 antibodies by adjuvants showed two distinct patterns of regulation by IL-4. The utilization of an IL-4 regulated pathway(s) for the induction of Th2-type antibodies by the same adjuvant differed between mouse strains, suggesting that animal species variability in responses to vaccine adjuvants may be due, at least in part, to differences in the utilization of immune system pathways by an adjuvant among animal hosts.
Invasion of Aortic and Heart Endothelial Cells by
Porphyromonas gingivalis
Authors: Deshpande Rajashri G. , Khan Mahfuz B. , Attardo Genco Caroline 
Published: December 2019

ABSTRACT

Invasion of host cells is believed to be an important strategy utilized by a number of pathogens, which affords them protection from the host immune system. The connective tissues of the periodontium are extremely well vascularized, which allows invading microorganisms, such as the periodontal pathogen
Porphyromonas gingivalis
, to readily enter the bloodstream. However, the ability of
P. gingivalis
to actively invade endothelial cells has not been previously examined. In this study, we demonstrate that
P. gingivalis
can invade bovine and human endothelial cells as assessed by an antibiotic protection assay and by transmission and scanning electron microscopy.
P. gingivalis
A7436 was demonstrated to adhere to and to invade fetal bovine heart endothelial cells (FBHEC), bovine aortic endothelial cells (BAEC), and human umbilical vein endothelial cells (HUVEC). Invasion efficiencies of 0.1, 0.2, and 0.3% were obtained with BAEC, HUVEC, and FBHEC, respectively. Invasion of FBHEC and BAEC by
P. gingivalis
A7436 assessed by electron microscopy revealed the formation of microvillus-like extensions around adherent bacteria followed by the engulfment of the pathogen within vacuoles. Invasion of BAEC by
P. gingivalis
A7436 was inhibited by cytochalasin D, nocodazole, staurosporine, protease inhibitors, and sodium azide, indicating that cytoskeletal rearrangements, protein phosphorylation, energy metabolism, and
P. gingivalis
proteases are essential for invasion. In contrast, addition of rifampin, nalidixic acid, and chloramphenicol had little effect on invasion, indicating that bacterial RNA, DNA, and de novo protein synthesis are not required for
P. gingivalis
invasion of endothelial cells. Likewise de novo protein synthesis by endothelial cells was not required for invasion by
P. gingivalis. P. gingivalis
381 was demonstrated to adhere to and to invade BAEC (0.11 and 0.1% efficiency, respectively). However, adherence and invasion of the corresponding
fimA
mutant DPG3, which lacks the major fimbriae, was not detected. These results indicate that
P. gingivalis
can actively invade endothelial cells and that fimbriae are required for this process.
P. gingivalis
invasion of endothelial cells may represent another strategy utilized by this pathogen to thwart the host immune response.
The Repertoire ofAnaplasma marginaleAntigens Recognized by CD4+T-Lymphocyte Clones from Protectively Immunized Cattle Is Diverse and Includes Major Surface Protein 2 (MSP-2) and MSP-3
Authors: Brown Wendy C. , Zhu Daming , Shkap Varda , McGuire Travis C. , Blouin Edmour F. , Kocan Katherine M. , Palmer Guy H. 
Published: December 2019

ABSTRACTMajor surface proteins ofAnaplasma marginaleare vaccine candidates. We recently demonstrated that immunization of calves with outer membranes of the Florida strain ofA. marginaleresulted in protective immunity that correlated with a memory CD4+T-lymphocyte response specific for major surface protein 1 (MSP-1), MSP-2, and MSP-3 (W. C. Brown, V. Shkap, D. Zhu, T. C. McGuire, W. Tuo, T. F. McElwain, and G. H. Palmer, Infect. Immun. 66:5406–5413, 1998). As immunogens, these proteins have been shown to induce complete or partial protection against homologous challenge. To further define the T helper (Th) cell response to these and otherA. marginaleantigens and to determine conservation of Th cell epitopes among genetically distinctA. marginalestrains, Th cell clones obtained prior to challenge from three immunized calves were characterized for antigen-specific responses. Nine distinct antigenic profiles were defined by 11 Th cell clones derived by stimulation with the Florida strain. Several clones responded to MSP-2, MSP-3, or both. All of these MSP-2- or MSP-3-specific clones and the majority of other clones that did not respond to MSPs recognized all bovine blood-passaged strains ofA. marginale. These results demonstrate conservation of certain Th cell epitopes between MSP-2 and MSP-3 and show that Th cell epitopes in MSP-2, MSP-3, and undefined antigens are conserved among strains ofA. marginale. Of seven clones that responded to the blood-passaged Virginia strain, two did not recognize antigen prepared from this strain cultured in tick cells, suggesting differences in the antigenic composition between these stages. Analysis of the cytokines expressed by the Th cells revealed that all clones expressed gamma interferon and tumor necrosis factor alpha, and most coexpressed interleukin-4. Our results provide a rationale for identifying Th cell epitopes conserved among different strains ofA. marginalefor inclusion in a nucleic acid or recombinant protein vaccine.