bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nuclear Translocation of NF-κB in Lipopolysaccharide-Treated Macrophages Fails To Correspond to Endotoxicity: Evidence Suggesting a Requirement for a Gamma Interferon-Like Signal
Authors: Denlinger Loren C. , Garis Kristen A. , Sommer Julie A. , Guadarrama Arturo G. , Proctor Richard A. , Bertics Paul J. 
Published: December 2019

ABSTRACTElucidation of a signal transduction pathway essential to lipopolysaccharide (LPS)-induced macrophage activation has the capacity to provide new targets for the treatment of septic shock. In this regard, activation of the transcription factor NF-κB is commonly thought to be critical to LPS-stimulated macrophage inflammatory mediator production, although certain immunological, genetic, and molecular evidence suggests that other factors are involved. To address this issue, we hypothesized that the degree of LPS-induced NF-κB mobilization should correlate with the murine endotoxicity of the species of LPS used for in vitro study. Therefore, usingd-galactosamine-sensitized mice, we assessed the lethal potencies of eight LPS preparations fromEscherichia,Salmonella,Klebsiella,Bacteroides,Pseudomonas,Neisseria, andRhodobacterspecies as well as that of the endotoxin substructure lipid X. The lethal potencies of these LPS preparations varied by >160-fold. Treatment of RAW 264.7 cells with the same LPS preparations induced levels of tumor necrosis factor alpha (TNF-α) and NO production that correlated with the LPS 50% lethal dose. The combined analysis of the levels of these two mediators produced in response to LPS in RAW cells was found to be a strong predictor of murine endotoxic lethality. Interestingly, while relatively nontoxic in mice,Rhodobacter capsulatusLPS stimulated RAW cell NF-κB-like DNA binding protein mobilization and TNF-α production to levels comparable to those of more toxic species of LPS but was unable to induce NO generation in RAW cells. These data indicate that neither NF-κB activation nor TNF-α production alone is a dependable predictor of LPS lethality. Additionally, cotreatment of RAW cells with the potent inflammatory mediator ADP had no effect on the ability ofR. capsulatusLPS to stimulate NO production but significantly enhanced induction of NO production by the toxic species of LPS. In contrast, cotreatment of RAW cells or peritoneal macrophages with gamma interferon (IFN-γ) normalized the abilities of both toxic and nontoxic LPS preparations to induce NO production, suggesting that selected preparations of LPS may preferentially generate an IFN-γ-like signal that accounts for enhanced toxicity. In sum, the activation of NF-κB does not correspond to LPS lethality, thereby complicating models of macrophage activation that highlight NF-κB alone as a signal transduction factor necessary for LPS-mediated toxicity.
Enhancement of Susceptibility to Shiga Toxin-Producing
Escherichia coli
O157:H7 by Protein Calorie Malnutrition in Mice
Authors: Kurioka Takaaki , Yunou Yoshihisa , Kita Eiji 
Published: December 2019

ABSTRACT

Infection with Shiga toxin (Stx)-producing enterohemorrhagic
Escherichia coli
is increasing among children. In this study, 5-week-old C57BL/6 mice with protein calorie malnutrition (PCM) that had been fed a 5% protein diet for 2 weeks since ablactation were inoculated intragastrically with 2 × 10
6
CFU of Stx-producing
E. coli
O157:H7. More than 75% of infected mice with PCM died by 10 days postinfection. Infected mice with PCM developed neurologic symptoms 5 days after infection, while well-nourished control mice receiving a 25% protein diet did not. In the intestinal tracts of infected mice with PCM, inoculated
E. coli
O157:H7 multiplied between days 2 and 4 of infection, with a peak of growth at day 4. Although the pathogens were not culturable from the stool after day 7, O157 lipopolysaccharide was detectable in the stool by enzyme-linked immunosorbent assay even after day 8. Stx was detectable in the stool after day 2 of infection and increased in proportion to the growth of inoculated organisms. The maximal production of Stx occurred at 4 days postchallenge, and Stx was detectable in the blood on days 3 to 5. In contrast, well-nourished control mice survived the infection, and all of them remained well even after 3 weeks of infection. In these control mice, inoculated
E. coli
O157:H7 disappeared from the stool before day 3. Stx was not detectable in the stool and blood of infected control mice at any time from day 1 through day 8. Histologically, cerebral hemorrhages seemed to be the cause of acute death of infected mice with PCM. Immunocytochemical staining demonstrated the positive immunoreaction to Stx at the alveus and stratum pyramidale of the hippocampus and in renal tubules of infected malnourished mice. Such immunoreactions were not found in tissues from infected control mice. Histological study of the intestinal epithelium before infection showed that PCM severely affected the development of intestinal epithelia. These findings strongly indicate that PCM-induced nondevelopment of intestinal physical barrier is one of the predisposing factors for infection with Stx-producing
E. coli
O157:H7 in mice and suggest that our mouse model may explain the high incidence of infection with Stx-producing
E. coli
O157:H7 in the children whose intestinal epithelia have not yet completely developed.
Aging and the Immune Response to theHaemophilus influenzaeType b Capsular Polysaccharide: Retention of the Dominant Idiotype and Antibody Function in the Elderly
Authors: Lucas Alexander H. , Reason Donald C. 
Published: December 2019

ABSTRACTAnti-Haemophilus influenzaeb polysaccharide (Hib PS) antibodies elicited in elderly subjects following conjugate vaccination expressed a light-chain variable-region (VL)-associated idiotype and had functional activities similar to those previously observed in children and younger adults. These findings indicate that advanced age is not accompanied by shifts in the major VLcomponent of the Hib PS-specific repertoire or by diminution of the protective function of antibodies.
MrpB Functions as the Terminator for Assembly of
Proteus mirabilis
Mannose-Resistant
Proteus
-Like Fimbriae
Authors: Li Xin , Mobley Harry L. T. 
Published: December 2019

ABSTRACT

Insertional mutagenesis studies of
mrpB
, a putative pilin-encoding open reading frame of the
mrp
gene cluster, which encodes mannose-resistant
Proteus
-like (MR/P) fimbriae of
Proteus mirabilis
, indicate that MrpB functions as the terminator for fimbrial assembly.
Distribution of Protein Kinase C Isoforms after Infection of Macrophages withLeishmania major
Authors: Pingel Sabine , Wang Zhi-En , Locksley Richard M. 
Published: December 2019

ABSTRACTWe characterized the effects ofLeishmaniainfection on activation-induced translocation of protein kinase C (PKC) isoforms in murine bone marrow-derived macrophages. Although PKC-dependent gene expression was attenuated by infection, the distribution and translocation of PKC isoforms were unaffected. However, subsequent dissociation from membranes was substantially delayed for some isoforms, particularly PKCβ.
Trafficking of Porin-Deficient
Salmonella typhimurium
Mutants inside HeLa Cells:
ompR
and
envZ
Mutants Are Defective for the Formation of
Salmonella
-Induced Filaments
Authors: Mills Scott D. , Ruschkowski Sharon R. , Stein Murry A. , Finlay B. Brett 
Published: December 2019

ABSTRACT

Outer membrane porin genes of
Salmonella typhimurium
, including
ompC
,
ompF
, and
tppB
, are regulated by the products of
ompB
, a two-component regulatory locus encoding OmpR and EnvZ.
S. typhimurium ompR
mutants are attenuated in mice, but to date no one has studied the intracellular trafficking of
S. typhimurium
porin-deficient mutants. In this study, isogenic transposon mutants of
S. typhimurium
with insertions in
ompR
,
envZ
,
ompF
,
ompC
,
ompD
,
osmZ
, and
tppB
were compared with wild-type SL1344 for trafficking in the human epithelial cell line HeLa. We found that
ompR
and
envZ
mutants were reduced or completely inhibited for the formation of
Salmonella
-induced filaments (Sifs). This result was confirmed with an
ompB
deletion mutant. Sifs are tubular structures containing lysosomal glycoprotein which are induced specifically by intracellular
Salmonella
. Genetic analysis showed that the
ompR
mutation could be complemented in
trans
by cloned
ompR
to restore its ability to induce Sifs. In contrast, mutations in the known
ompR
-regulated genes
ompF
,
ompC
, and
tppB
(as well as the
ompR
-independent porin gene,
ompD
) had no effect on Sif formation relative to that of wild-type SL1344, thus indicating that OmpR does not exert its role on these genes to induce Sif formation. The
omp
mutants studied were able to invade and replicate in HeLa cells at levels comparable to those in wild-type SL1344. We conclude that OmpR and EnvZ appear to regulate Sif formation triggered by intracellular
S. typhimurium.
Helicobacter pylori
Glutamine Synthetase Lacks Features Associated with Transcriptional and Posttranslational Regulation
Authors: Garner Rachel M. , Fulkerson John , Mobley Harry L. T. 
Published: December 2019

ABSTRACT

Helicobacter pylori
urease, produced in abundance, is indispensable for the survival of
H. pylori
in animal hosts. Urea is hydrolyzed by the enzyme, resulting in the liberation of excess ammonia, some of which neutralizes gastric acid. The remaining ammonia is assimilated into protein by glutamine synthetase (EC
6.3.1.2
), which catalyzes the reaction: NH
3
+ glutamate + ATP→glutamine + ADP + P
i
. We hypothesized that glutamine synthetase plays an unusually critical role in nitrogen assimilation by
H. pylori
. We developed a phenotypic screen to isolate genes that contribute to the synthesis of a catalytically active urease.
Escherichia coli
SE5000 transformed with plasmid pHP808 containing the entire
H. pylori
urease gene cluster was cotransformed with a pBluescript plasmid library of the
H. pylori
ATCC 43504 genome. A weakly urease-positive 9.4-kb clone, pUEF728, was subjected to nucleotide sequencing. Among other genes, the gene for glutamine synthetase was identified. The complete 1,443-bp
glnA
gene predicts a polypeptide of 481 amino acid residues with a molecular weight of 54,317; this was supported by maxicell analysis of cloned
glnA
expressed in
E. coli
. The top 10 homologs were all bacterial glutamine synthetases, including
Salmonella typhimurium glnA
. The ATP-binding motif GDNGSG (residues 272 to 277) of
H. pylori
GlnA exactly matched and aligned with the sequence in 8 of the 10 homologs. The adenylation site found in the top 10 homologs (consensus sequence, NLYDLP) is replaced in
H. pylori
by NLFKLT (residues 405 to 410). Since the Tyr (Y) residue is the target of adenylation and since the
H. pylori
glutamine synthetase lacks that residue in four strains examined, we conclude that no adenylation occurs within this motif. Cloned
H. pylori glnA
complemented a
glnA
mutation in
E. coli
, and GlnA enzyme activity could be measured spectrophotometrically. In an attempt to produce a GlnA-deficient mutant of
H. pylori
, a kanamycin resistance cassette was cloned into the
Tth
111I site of
H. pylori glnA
. By using the standard technique of allelic exchange mutagenesis, no verifiable glutamine synthetase double-crossover mutant of strain UMAB41 could be isolated, suggesting that the mutation is lethal. We conclude that glutamine synthetase is critical for nitrogen assimilation in
H. pylori
and is active under all physiologic conditions.
Immunization of Cattle by Infection withCowdria ruminantiumElicits T Lymphocytes That Recognize Autologous, Infected Endothelial Cells and Monocytes
Authors: Mwangi Duncan M. , Mahan Suman M. , Nyanjui John K. , Taracha Evans L. N. , McKeever Declan J. 
Published: December 2019

ABSTRACTPeripheral blood mononuclear cells (PBMC) from immune cattle proliferate in the presence of autologousCowdria ruminantium-infected endothelial cells and monocytes. Endothelial cells required treatment with T-cell growth factors to induce class II major histocompatibility complex expression prior to infection and use as stimulators. Proliferative responses to both infected autologous endothelial cells and monocytes were characterized by expansion of a mixture of CD4+, CD8+, and γδ T cells. However, γδ T cells dominated following several restimulations. Reverse transcription-PCR analysis of cytokine expression byC. ruminantium-specific T-cell lines and immune PBMC revealed weak interleukin-2 (IL-2), IL-4, and gamma interferon (IFN-γ) transcripts at 3 to 24 h after stimulation. Strong expression of IFN-γ, tumor necrosis factor alpha (TNF-α), TNF-β, and IL-2 receptor α-chain mRNA was detected in T-cell lines 48 h after antigen stimulation. Supernatants from these T-cell cultures contained IFN-γ protein. Our findings suggest that in immune cattle aC. ruminantium-specific T-cell response is induced and that infected endothelial cells and monocytes may presentC. ruminantiumantigens to specific T lymphocytes in vivo during infection and thereby play a role in induction of protective immune responses to the pathogen.
Nasopharyngeal Colonization with Nontypeable
Haemophilus influenzae
in Chinchillas
Authors: Yang Yan-ping , Loosmore Sheena M. , Underdown Brian J. , Klein Michel H. 
Published: December 2019

ABSTRACT

Colonization of the nasopharynx by a middle ear pathogen is the first step in the development of otitis media in humans. The establishment of an animal model of nasopharyngeal colonization would therefore be of great utility in assessing the potential protective ability of candidate vaccine antigens (especially adhesins) against otitis media. A chinchilla nasopharyngeal colonization model for nontypeable
Haemophilus influenzae
(NTHI) was developed with antibiotic-resistant strains. This model does not require coinfection with a virus. There was no significant difference in the efficiency of NTHI colonization between adult (1- to 2-year-old) and young (2- to 3-month-old) animals. However, the incidence of middle ear infection following nasopharyngeal colonization was significantly higher in young animals (83 to 89%) than in adult chinchillas (10 to 30%). Chinchillas that had recovered either from a previous middle ear infection caused by NTHI or from an infection by intranasal inoculation with NTHI were completely protected against nasopharyngeal colonization with a homologous strain and were found to be the best positive controls in protection studies. Systemic immunization of chinchillas with inactivated whole-cell preparations significantly protected animals not only against homologous NTHI colonization but also partially against heterologous NTHI infection. In all protected animals, significant serum anti-P6 and anti-HMW antibody responses were observed. The outer membrane P6 and high-molecular-weight (HMW) proteins appear to be promising candidate vaccine antigens to prevent nasopharyngeal colonization and middle ear infection caused by NTHI.
Ambiguous Role of Interleukin-12 inYersinia enterocoliticaInfection in Susceptible and Resistant Mouse Strains
Authors: Bohn Erwin , Schmitt Edgar , Bielfeldt Claudia , Noll Annette , Schulte Ralf , Autenrieth Ingo B. 
Published: December 2019

ABSTRACTEndogenous interleukin-12 (IL-12) mediates protection againstYersinia enterocoliticain C57BL/6 mice by triggering gamma interferon (IFN-γ) production in NK and CD4+T cells. Administration of exogenous IL-12 confers protection against yersiniae inYersinia-susceptible BALB/c mice but exacerbates yersiniosis in resistant C57BL/6 mice. Therefore, we wanted to dissect the different mechanisms exerted by IL-12 duringYersiniainfections by using different models ofYersinia-resistant and -susceptible mice, including resistant C57BL/6 mice, susceptible BALB/c mice, intermediate-susceptible wild-type 129/Sv mice, 129/Sv IFN-γ-receptor-deficient (IFN-γR−/−) mice and C57BL/6 tumor necrosis factor (TNF) receptor p55 chain-deficient (TNFR p55−/−) mice. IFN-γR−/−mice turned out to be highly susceptible to infection byY. enterocoliticacompared with IFN-γR+/+mice. Administration of IL-12 was protective in IFN-γR+/+mice but not in IFN-γR−/−mice, suggesting that IFN-γR-induced mechanisms are essential for IL-12-induced resistance against yersiniae. BALB/c mice could be renderedYersiniaresistant by administration of anti-CD4 antibodies or by administration of IL-12. In contrast, C57BL/6 mice could be rendered more resistant by administration of transforming growth factor β (TGF-β). Furthermore, IL-12-triggered toxic effects in C57BL/6 mice were abrogated by coadministration of TGF-β. While administration of IL-12 alone increased TNF-α levels, administration of TGF-β or TGF-β plus IL-12 decreased both TNF-α and IFN-γ levels inYersinia-infected C57BL/6 mice. Moreover, IL-12 did not induce toxicity inYersinia-infected TNFR p55−/−mice, suggesting that TNF-α accounts for IL-12-induced toxicity. Taken together, IL-12 may induce different effector mechanisms in BALB/c and C57BL/6 mice resulting either in protection or exacerbation. These results are important for understanding the critical balance of proinflammatory and regulatory cytokines in bacterial infections which is decisive for beneficial effects of cytokine therapy.
Production of Monocyte Chemoattractant Protein 1 in Tuberculosis Patients
Authors: Lin YuanGuang , Gong JianHua , Zhang Ming , Xue Wanfen , Barnes Peter F. 
Published: December 2019

ABSTRACTTo investigate the role of monocyte chemoattractant protein 1 (MCP-1) in the immune response toMycobacterium tuberculosis, we studied MCP-1 production in tuberculosis patients. CD14+blood monocytes from tuberculosis patients spontaneously expressed higher levels of MCP-1 mRNA and protein than CD14+monocytes from healthy tuberculin reactors. MCP-1 production in lymph nodes from tuberculosis patients was also markedly increased. These findings suggest that MCP-1 can contribute to the antimycobacterial inflammatory response by attracting monocytes and T lymphocytes.
Localization of
Chlamydia trachomatis
Heat Shock Proteins 60 and 70 during Infection of a Human Endometrial Epithelial Cell Line In Vitro
Authors: Raulston Jane E. , Paul Terry R. , Knight Stephen T. , Wyrick Priscilla B. 
Published: December 2019

ABSTRACT

Unlike chlamydial lipopolysaccharide, which is released from the developing inclusion to the surface of infected genital epithelial cells, both
Chlamydia trachomatis
heat shock protein (hsp) 60 and 70 antigens remained confined within the inclusion during the course of the chlamydial developmental cycle. Exposure of the infected cells to penicillin to induce a persistent infection or to a lipophilic microbicide did not potentiate secretion or exocytosis of the chlamydial hsp.
Structure-Function Relationship of Antibacterial Synthetic Peptides Homologous to a Helical Surface Region on Human Lactoferrin against
Escherichia coli
Serotype O111
Authors: Chapple Daniel S. , Mason David J. , Joannou Christopher L. , Odell Edward W. , Gant Vanya , Evans Robert W. 
Published: December 2019

ABSTRACT

Lactoferricin includes an 11-amino-acid amphipathic alpha-helical region which is exhibited on the outer surface of the amino-terminal lobe of lactoferrin. Synthetic peptides homologous to this region exhibited potent antibacterial activity against a selected range of both gram-negative and gram-positive bacteria. An analog synthesized with methionine substituted for proline at position 26, which is predicted to disrupt the helical region, abolished antibacterial activity against
Escherichia coli
and considerably reduced antibacterial activity against
Staphylococcus aureus
and an
Acinetobacter
strain. The mode of action of human lactoferrin peptide (HLP) 2 against
E. coli
serotype O111 (NCTC 8007) was established by using flow cytometry, surface plasmon resonance, and transmission electron microscopy. Flow cytometry was used to monitor membrane potential, membrane integrity, and metabolic processes by using the fluorescent probes bis-1,3-(dibutylbarbituric acid)-trimethine oxonol, propidium iodide, and carbonyl cyanide
m
-chlorophenylhydrazone, respectively. HLP 2 was found to act at the cell membrane, causing complete loss of membrane potential after 10 min and of membrane integrity within 30 min, with irreversible damage to the cell as shown by rapid loss of viability. The number of particles, measured by light scatter on the flow cytometer, dropped significantly, showing that bacterial lysis resulted. The peptide was shown to bind to
E. coli
O111 lipopolysaccharide by using surface plasmon resonance. Transmission electron microscopy revealed bacterial distortion, with the outer membrane becoming detached from the inner cytoplasmic membrane. We conclude that HLP 2 causes membrane disruption of the outer membrane, resulting in lysis, and that structural considerations are important for antibacterial activity.
Lipopolysaccharide-Related Stimuli Induce Expression of the Secretory Leukocyte Protease Inhibitor, a Macrophage-Derived Lipopolysaccharide Inhibitor
Authors: Jin Fenyu , Nathan Carl F. , Radzioch Danuta , Ding Aihao 
Published: December 2019

ABSTRACTMouse secretory leukocyte protease inhibitor (SLPI) was recently characterized as a lipopolysaccharide (LPS)-induced product of macrophages that antagonizes their LPS-induced activation of NF-κB and production of NO and tumor necrosis factor (TNF) (F. Y. Jin, C. Nathan, D. Radzioch, and A. Ding, Cell 88:417–426, 1997). To better understand the role of SLPI in innate immune and inflammatory responses, we examined the kinetics of SLPI expression in response to LPS, LPS-induced cytokines, and LPS-mimetic compounds. SLPI mRNA was detectable in macrophages by Northern blot analysis within 30 min of exposure to LPS but levels peaked only at 24 to 36 h and remained elevated at 72 h. Despite the slowly mounting and prolonged response, early expression of SLPI mRNA was cycloheximide resistant. Two LPS-induced proteins—interleukin-10 (IL-10) and IL-6—also induced SLPI, while TNF and IL-1β did not. The slow attainment of maximal induction of SLPI by LPS in vitro was mimicked by infection withPseudomonas aeruginosain vivo, where SLPI expression in the lung peaked at 3 days. Two LPS-mimetic molecules—taxol from yew bark and lipoteichoic acid (LTA) from gram-positive bacterial cell walls—also induced SLPI. Transfection of macrophages with SLPI inhibited their LTA-induced NO production. An anti-inflammatory role for macrophage-derived SLPI seems likely based on SLPI’s slowly mounting production in response to constituents of gram-negative and gram-positive bacteria, its induction both as a direct response to LPS and as a response to anti-inflammatory cytokines induced by LPS, and its ability to suppress the production of proinflammatory products by macrophages stimulated with constituents of both gram-positive and gram-negative bacteria.