bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mitogenic Response of Murine B Lymphocytes toSalmonella typhimuriumLipopolysaccharide Requires Protein Kinase C-Dependent Late Tyrosine Phosphorylations
Authors: Mey Anne , Revillard Jean-Pierre 
Published: December 2019

ABSTRACTUnlike the cross-linking of membrane immunoglobulins, the activation of B cells by lipopolysaccharide (LPS) does not involve the phosphoinositol turnover and the initial activation of tyrosine kinases. However, LPS-induced B-cell proliferation was inhibited by the tyrosine kinase inhibitors genistein and herbimycin A even when added 48 h after the beginning of the culture. Tyrosyl-phosphorylated proteins were detected by Western blotting after 24 h of culture with LPS, reaching a maximum concentration after 72 h. Late tyrosine phosphorylations were also detected in B cells activated for 72 h with anti-immunoglobulin M antibody and were abrogated by the protein synthesis inhibitor cycloheximide, the tyrosine kinase inhibitors genistein and herbimycin A, and the protein kinase C inhibitor chelerythrine. The role of protein kinase C in late tyrosine kinase activation is independent of Ca2+mobilization and was confirmed by detection of a comparable but restricted pattern of tyrosine-phosphorylated substrates in B cells treated with phorbol myristate acetate alone or in association with ionomycin. Tyrosine kinase activation was dependent on de novo protein synthesis. However, culture supernatants of LPS-activated B cells were devoid of mitogenic activity and induced a phosphorylation pattern more restricted than that achieved by LPS. Altogether these data indicate that proliferation signals induced by LPS or by the cross-linking of membrane immunoglobulins are controlled by late tyrosine phosphorylations occurring throughout the first 3 days of culture, controlled in part by protein kinase C activation, and dependent on the synthesis of an intermediate protein(s) either not secreted in the culture supernatant or present but biologically inactive in naive B cells.
Lipopolysaccharide and Its Analog Antagonists Display Differential Serum Factor Dependencies for Induction of Cytokine Genes in Murine Macrophages
Authors: Perera Pin-Yu , Qureshi Nilofer , Christ William J. , Stütz Peter , Vogel Stefanie N. 
Published: December 2019

ABSTRACTMonocytes/macrophages play a central role in mediating the effects of lipopolysaccharide (LPS) derived from gram-negative bacteria by the production of proinflammatory mediators. Recently, it was shown that the expression of cytokine genes for tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and interferon-inducible protein-10 (IP-10) by murine macrophages in response to low concentrations of LPS is entirely CD14 dependent. In this report, we show that murine macrophages respond to low concentrations of LPS (≤2 ng/ml) in the complete absence of serum, leading to the induction of TNF-α and IL-1β genes. In contrast to the TNF-α and IL-1β genes, the IP-10 gene is poorly induced in the absence of serum. The addition of recombinant human soluble CD14 (rsCD14) had very little effect on the levels of serum-free, LPS-induced TNF-α, IL-1β, and IP-10 genes. In contrast, the addition of recombinant human LPS-binding protein (rLBP) had opposing effects on the LPS-induced TNF-α or IL-1β and IP-10 genes. rLBP inhibited LPS-induced TNF-α and IL-1β genes, while it reconstituted IP-10 gene expression to levels induced in the presence of serum. These results provide further evidence that the induction of TNF-α or IL-1β genes occurs via a pathway that is distinct from one that leads to the induction of the IP-10 gene and that the pathways diverge at the level of the initial interaction between LPS and cellular CD14. Additionally, the results presented here indicate that LPS structural analog antagonistsRhodobacter sphaeroidesdiphosphoryl lipid A and SDZ 880.431 are able to inhibit LPS-induced TNF-α and IL-1β in the absence of serum, while a synthetic analog ofRhodobacter capsulatuslipid A (B 975) requires both rsCD14 and rLBP to function as an inhibitor.
Modification of Ras in Eukaryotic Cells by
Pseudomonas aeruginosa
Exoenzyme S
Authors: McGuffie Eileen M. , Frank Dara W. , Vincent Timothy S. , Olson Joan C. 
Published: December 2019

ABSTRACT

Genetic and functional data suggest that
Pseudomonas aeruginosa
exoenzyme S (ExoS), an ADP-ribosyltransferase, is translocated into eukaryotic cells by a bacterial type III secretory mechanism activated by contact between bacteria and host cells. Although purified ExoS is not toxic to eukaryotic cells, ExoS-producing bacteria cause reduced proliferation and viability, possibly mediated by bacterially translocated ExoS. To investigate the activity of translocated ExoS, we examined in vivo modification of Ras, a preferred in vitro substrate. The ExoS-producing strain
P. aeruginosa
388 and an isogenic mutant strain, 388Δ
exoS
, which fails to produce ExoS, were cocultured with HT29 colon carcinoma cells. Ras was found to be ADP-ribosylated during coculture with 388 but not with 388Δ
exoS
, and Ras modification by 388 corresponded with reduction in HT29 cell DNA synthesis. Active translocation by bacteria was found to be required, since exogenous ExoS, alone or in the presence of 388Δ
exoS
, was unable to modify intracellular Ras. Other ExoS-producing strains caused modification of Ras, indicating that this is not a strain-specific event. ADP-ribosylation of Rap1, an additional Ras family substrate for ExoS in vitro, was not detectable in vivo under conditions sufficient for Ras modification, suggesting possible ExoS substrate preference among Ras-related proteins. These results confirm that intracellular Ras is modified by bacterially translocated ExoS and that the inhibition of target cell proliferation correlates with the efficiency of Ras modification.
Clostridium difficileToxin B Induces Apoptosis in Intestinal Cultured Cells
Authors: Fiorentini Carla , Fabbri Alessia , Falzano Loredana , Fattorossi Andrea , Matarrese Paola , Rivabene Roberto , Donelli Gianfranco 
Published: December 2019

ABSTRACTToxigenic strains of the anaerobic bacteriumClostridium difficileproduce at least two large, single-chain protein exotoxins involved in the pathogenesis of antibiotic-associated diarrhea and colitis. Toxin A (CdA) is a cytotoxic enterotoxin, while toxin B (CdB) is a more potent cytotoxin lacking enterotoxic activity. This study dealt with CdB, providing the first evidence that intestinal cells exposed to this toxin exhibit typical features of apoptosis in that a significant proportion of the treated cells displayed nuclear fragmentation and chromatin condensation. In keeping with ultrastructural data, CdB-treated cells showed the typical flow cytometric hallmark of apoptosis consisting of a distinct sub-G1peak. The CdB-induced apoptotic response was dose and time dependent and not simply due to the actin-disrupting effect of the toxin or to the subsequent impairment of cell anchorage. Rather, the inhibition of proteins belonging to the Rho family due to CdB seems to play a role in the induction of apoptosis in intestinal cells. The origin of cells and the growth rate may also be cofactors relevant to such a response.
Secretory Phospholipase A
2
Is the Principal Bactericide for Staphylococci and Other Gram-Positive Bacteria in Human Tears
Authors: Qu Xiao-Dan , Lehrer Robert I. 
Published: December 2019

ABSTRACT

We examined human tears for molecules that killed gram-positive bacteria. The principal mediator of bactericidal activity against staphylococci proved to be a calcium-dependent enzyme, secretory phospholipase A
2
. Whereas the concentration of secretory phospholipase A
2
in the normal tear film exceeded 30 μg/ml, only 1.1 ng (<0.1 nM) of the enzyme per ml sufficed to kill
Listeria monocytogenes
and 15 to 80 ng/ml killed
Staphylococcus aureus
. Despite its efficacy against gram-positive bacteria, secretory phospholipase A
2
lacked bactericidal activity against gram-negative organisms (
Escherichia coli
,
Salmonella typhimurium
, and
Pseudomonas aeruginosa
) when tested in the ionic environment of tears. Given the presence of secretory phospholipase A
2
in tears, intestinal secretions, and leukocytes, this enzyme may play a substantial role in innate mucosal and systemic bactericidal defenses against gram-positive bacteria.
Time Course and Host Responses toEscherichia coliUrinary Tract Infection in Genetically Distinct Mouse Strains
Authors: Hopkins Walter J. , Gendron-Fitzpatrick Annette , Balish Edward , Uehling David T. 
Published: December 2019

ABSTRACTRecurrent urinary tract infections (UTIs) are a significant clinical problem for many women; however, host susceptibility factors have not been completely defined. The mouse model of induced UTI provides an experimental environment in which to identify specific host characteristics that are important in initial bacterial colonization of the urinary tract and in resolution of an infection. This study examined initial susceptibility, bacterial clearance, and host defense mechanisms during induction and resolution ofEscherichia coliUTIs in genetically distinct strains of mice. Of the ten inbred strains tested, six (BALB/c, C3H/HeN, C57BL/6, DBA.1, DBA.2, and AKR) showed progressive resolution of bladder infections over a 14-day period. A constant, low-level bladder infection was observed in SWR and SJL mice. High bladder infection levels persisted over the 14-day study period in C3H/HeJ and C3H/OuJ mice. Kidney infection levels generally correlated with bladder infection levels, especially in C3H/HeJ and C3H/OuJ mice, the two most susceptible strains, in which infections became more severe with time after challenge. The degree of inflammation in bladder and kidneys, as well as antibody-forming cell responses, positively correlated with infection intensity in all strains except C3H/HeJ, which had minimal inflammation despite high infection levels. These results demonstrate two important aspects of host defense against UTI. First, the innate immune response to an infection in the bladder or kidneys consists primarily of local inflammation, which is followed by an adaptive response characterized in part by an antibody response to the infecting bacteria. Second, a UTI will be spontaneously resolved in most cases; however, in mice with specific genetic backgrounds, a UTI can persist for an extended length of time. The latter result strongly suggests that the presence or absence of specific host genes will determine how effectively anE. coliUTI will be resolved.
The ImmunodominantBrugia malayiParamyosin as a Marker of Current Infection withWuchereria bancroftiAdult Worms
Authors: Langy Sandra , Plichart Catherine , Luquiaud Patrick , Williams Steven A. , Nicolas Luc 
Published: December 2019

ABSTRACTThe full-length cDNA sequence encodingBrugia malayiL3 paramyosin has been isolated by immunoscreening a cDNA library with a mouse antiserum raised againstWuchereria bancroftiL3 infective larvae. A recombinant truncated form of paramyosin was expressed as a glutathioneS-transferase fusion protein and used to evaluate humoral responses of adults from aW. bancrofti-endemic area in French Polynesia according to their parasitological status. Immunoglobulin G4 (IgG4) preferentially bound to paramyosin inW. bancrofti-parasitized individuals, in contrast to unparasitized individuals, who harbored neither microfilaria nor Og4C3 adult worm circulating antigen. Reduction of the anti-paramyosin IgG4 titer following combined chemotherapy with diethylcarbamazine and ivermectin was significantly correlated with a reduction in the adult worm burden. This indicates that the presence of paramyosin-reactive IgG4 is associated with the presence of parasites and that reduction can be used as an immunological marker forW. bancrofticlearance.
Characterization of the Type 3 Fimbrial Adhesins of
Klebsiella
Strains
Authors: Sebghati Tricia A. Schurtz , Korhonen Timo K. , Hornick Douglas B. , Clegg Steven 
Published: December 2019

ABSTRACT

The
Klebsiella pneumoniae
fimbrial adhesin, MrkD, mediates adherence to the basolateral surfaces of renal and pulmonary epithelia and to the basement membranes of tissues. Although all isolates possessing the MrkD adhesin mediate the agglutination, in vitro, of erythrocytes treated with tannic acid, the
mrkD
gene is not conserved within species. The ability of a plasmid-borne
mrkD
gene product to mediate binding to type V collagen is associated frequently with strains of
K. oxytoca
and rarely with strains of
K. pneumoniae
. In
K. pneumoniae
, the MrkD adhesin is located within a chromosomally borne gene cluster and mediates binding to collagen types IV and V. The plasmid-borne determinant,
mrkD
1P
, and the chromosomally borne gene,
mrkD
1C
, are not genetically related. Some strains of enterobacteria possess a
mrkD
1C
allele that is associated with hemagglutinating activity but does not bind to either type IV or type V collagen.
Physical Limitations onSalmonella typhiEntry into Cultured Human Intestinal Epithelial Cells
Authors: Huang Xiao-Zhe , Tall Ben , Schwan William R. , Kopecko Dennis J. 
Published: December 2019

ABSTRACTKinetic studies ofSalmonella typhiinvasion of INT407 cells at different multiplicities of infection (MOIs) have revealed a strict physical limitation onS. typhientry at MOIs of ≥40. Staining of infected monolayers to distinguish intracellular from extracellular bacteria revealed that all monolayer cells are susceptible to infection and that internalized bacteria are typically contained in one to three separate clusters per cell during the first 60 min. Scanning and transmission electron microscopic analyses of time course-infected monolayers showed that at early times postinfection, bacteria bind to shortened, coalesced microvilli in one to three focal aggregate structures per host cell surface. As reported previously forS. typhimurium, focal aggregates progress to conical membrane ruffles that appear to engulf one or a few centrally containedS. typhicells by a macropinocytic process, which enhanced the entry of simultaneously addedEscherichia coliHB101 about 30-fold. Additionally, kinetic studies showed that at an MOI of ≃400, maximalS. typhientry is virtually completed within 30 to 35 min. Monolayers pretreated withS. typhifor 30 min to saturate the entry process were severely reduced in the ability to internalize subsequently added kanamycin-resistant strains ofS. typhiorS. typhimurium, butE. coliHB101(pRI203) expressing the clonedYersinia invgene was not reduced in entry. In invasion inhibition assays, anti-β1 integrin antibodies markedly reducedE. coliHB101(pRI203) invasion efficiency but did not reduceS. typhientry. Collectively, these data provide direct physical and visual evidence which indicates thatS. typhiorganisms are internalized at a limited number (i.e., two to four) of sites on host cells.S. typhiandS. typhimuriumlikely share INT407 cell entry receptors which do not appear to be members of the β1 integrin superfamily.
Protective Roles of γδ T Cells and Interleukin-15 inEscherichia coliInfection in Mice
Authors: Takano M. , Nishimura H. , Kimura Y. , Mokuno Y. , Washizu J. , Itohara S. , Nimura Y. , Yoshikai Y. 
Published: December 2019

ABSTRACTThe number of γδ T cells in the peritoneal cavity was increased after an intraperitoneal (i.p.) infection withEscherichia coliin lipopolysaccharide (LPS)-responsive C3H/HeN mice but not in LPS-hyporesponsive C3H/HeJ mice. The γδ T cells preferentially expressed invariant Vγ6 and Vδ1 chains and proliferated to produce a large amount of gamma interferon in the presence of LPS. Mice depleted of γδ T cells by T-cell receptor δ gene mutation showed impaired resistance againstE. colias assessed by bacterial growth. Macrophages from C3H/HeN mice infected withE. coliexpressed higher levels of interleukin-15 (IL-15) mRNA than those from the infected C3H/HeJ mice. Administration of anti-IL-15 monoclonal antibody inhibited, albeit partially, the appearance of γδ T cells in C3H/HeN mice afterE. coliinfection and diminished the host defense against the infection. These results suggest that LPS-stimulated γδ T cells play an important role in the host defense againstE. coliinfection and that IL-15 may be partly involved in the protection via an increase in the γδ T cells.
Nonspecific Early Protective Immunity inFrancisellaandListeriaInfections Can Be Dependent on Lymphocytes
Authors: Elkins Karen L. , MacIntyre Ann T. , Rhinehart-Jones Tonya R. 
Published: December 2019

ABSTRACTNormal mice, but not lymphocyte-deficient or B-cell-deficient mice, given a sublethal infection ofFrancisella tularensisLVS survive a secondary lethal challenge of more than 10,000 50% lethal doses given 3 days later. In this work, we show that similar early protection that is also strongly lymphocyte dependent operates inListeria monocytogenesinfection. Since sublethal infection with either LVS orL. monocytogenesprotects against heterologous lethal challenge, this early protection is nonspecific.
Organization of
Escherichia coli
O157 O Antigen Gene Cluster and Identification of Its Specific Genes
Authors: Wang Lei , Reeves Peter R. 
Published: December 2019

ABSTRACT

The O157:H7 clone of
Escherichia coli
, which causes major, often prolonged outbreaks of gastroenteritis with hemolytic-uremic syndrome (HUS) such as those in Japan, Scotland, and the United States recently, is thought to be resident normally in cattle or other domestic animals. This clone is of major significance for public health and the food industry. We have developed a fast method for sequencing a given O antigen gene cluster and applied it to O157. The O157 O antigen gene cluster is 14 kb in length, comprising 12 genes and a remnant H-repeat unit. Based on sequence similarity, we have identified all the necessary O antigen genes, including five sugar biosynthetic pathway genes, four transferase genes, the O unit flippase gene, and the O antigen polymerase gene. By PCR testing against all 166
E. coli
O serogroups and a range of gram-negative bacterial strains, including some that cross-react serologically with
E. coli
O157 antisera, we have found that certain O antigen genes are highly specific to O157
E. coli
. This work provides the basis for a sensitive test for rapid detection of O157
E. coli
. This is important both for decisions on patient care, since early treatment may reduce the risk of life-threatening complications, and for detection of sources of contamination. The method for fast sequencing of O antigen gene clusters plus an ability to predict which genes will be O antigen specific will enable PCR tests to be developed as needed for other clones of
E. coli
or, once flanking genes are identified, clones of any gram-negative bacterium.
Pulmonary and Hepatic Gene Expression following Cecal Ligation and Puncture: Monophosphoryl Lipid A Prophylaxis Attenuates Sepsis-Induced Cytokine and Chemokine Expression and Neutrophil Infiltration
Authors: Salkowski Cindy A. , Detore Gregory , Franks Alice , Falk Michael C. , Vogel Stefanie N. 
Published: December 2019

ABSTRACTPolymicrobial sepsis induced by cecal ligation and puncture (CLP) reproduces many of the pathophysiologic features of septic shock. In this study, we demonstrate that mRNA for a broad range of pro- and anti-inflammatory cytokine and chemokine genes are temporally regulated after CLP in the lung and liver. We also assessed whether prophylactic administration of monophosphoryl lipid A (MPL), a nontoxic derivative of lipopolysaccharide (LPS) that induces endotoxin tolerance and attenuates the sepsis syndrome in mice after CLP, would alter tissue-specific gene expression post-CLP. Levels of pulmonary interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), granulocyte colony-stimulating factor (G-CSF), IL-1 receptor antagonist (IL-1ra), and IL-10 mRNA, as well as hepatic IL-1β, IL-6, gamma interferon (IFN-γ), G-CSF, inducible nitric oxide synthase, and IL-10 mRNA, were reduced in MPL-pretreated mice after CLP compared to control mice. Chemokine mRNA expression was also profoundly mitigated in MPL-pretreated mice after CLP. Specifically, levels of pulmonary and hepatic macrophage inflammatory protein 1α (MIP-1α), MIP-1β, MIP-2, and monocyte chemoattractant protein-1 (MCP-1) mRNA, as well as hepatic IFN-γ-inducible protein 10 and KC mRNA, were attenuated in MPL-pretreated mice after CLP. Attenuated levels of IL-6, TNF-α, MCP-1, MIP-1α, and MIP-2 in serum also were observed in MPL-pretreated mice after CLP. Diminished pulmonary chemokine mRNA production was associated with reduced neutrophil margination and pulmonary myeloperoxidase activity. These data suggest that prophylactic administration of MPL mitigates the sepsis syndrome by reducing chemokine production and the recruitment of inflammatory cells into tissues, thereby attenuating the production of proinflammatory cytokines.
Use ofMycobacterium tuberculosisComplex-Specific Antigen Cocktails for a Skin Test Specific for Tuberculosis
Authors: Lyashchenko Konstantin , Manca Claudia , Colangeli Roberto , Heijbel Anna , Williams Alan , Gennaro Maria Laura 
Published: December 2019

ABSTRACTThe tuberculin skin test currently used to diagnose infection withMycobacterium tuberculosishas poor diagnostic value, especially in geographic areas where the prevalence of tuberculosis is low or where the environmental burden of saprophytic, nontuberculous mycobacteria is high. Inaccuracy of the tuberculin skin test often reflects a low diagnostic specificity due to the presence in tuberculin of antigens shared by many mycobacterial species. Thus, a skin test specific for tuberculosis requires the development of new tuberculins consisting of antigens specific toM. tuberculosis. We have formulated cocktails of two to eight antigens ofM. tuberculosispurified from recombinantEscherichia coli. Multiantigen cocktails were evaluated by skin testing guinea pigs sensitized withM. bovisBCG. Reactivity of multiantigen cocktails was greater than that of any single antigen. Cocktail activity increased with the number of antigens in the cocktail even when the same amount of total protein was used for cocktails and for each single antigen. A cocktail of four purified antigens specific for theM. tuberculosiscomplex elicited skin test responses only in BCG-immunized guinea pigs, not in control animals immunized withM. avium. These findings open the way to designing a multiantigen formulation for a skin test specific for tuberculosis.
Synthesis of Microcapsule byStaphylococcus aureusIs Not Responsive to Environmental Phosphate Concentrations
Authors: Fox Karen F. , Stewart George C. , Fox Alvin 
Published: December 2019

ABSTRACTThe polysaccharide microcapsule ofStaphylococcus aureushas been reported to be differentially expressed depending on growth conditions, with phosphate concentration being the critical environmental component. This study evaluated the effect of growth of a serotype 8 strain ofS. aureusin phosphate-replete and phosphate-limiting media on microcapsule production. The presence of the cell wall polymers microcapsule and teichoic acid was measured by both gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. Production of microcapsule was unaffected by changes in the environmental phosphate concentration. There was, additionally, no evidence for a shift from teichoic acid to teichuronic acid synthesis.