bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gamma Interferon Stimulates Rat Alveolar Macrophages To KillPneumocystis cariniibyl-Arginine- and Tumor Necrosis Factor-Dependent Mechanisms
Authors: Downing James F. , Kachel Diane L. , Pasula Rajamouli , Martin William J. 
Published: December 2019

ABSTRACTPneumocystis cariniipneumonia remains a serious complication for immunocompromised patients. In the present study,P. cariniiorganisms interacted with gamma interferon (IFN-γ)-stimulated alveolar macrophages (AMs) to activate thel-arginine-dependent cytocidal pathway involving reactive nitrogen intermediates (RNI) that were assayed as nitrite (NO2−). Unstimulated cultures of AMs produced negligible quantities of RNI. Addition ofP. cariniiorganisms to IFN-γ-primed AMs resulted in greatly enhanced production of RNI. NO2−levels increased from 0.8 ± 0.4 to 11.1 ± 3.8 μM as early as 6 h afterP. cariniiorganisms were incubated with IFN-γ-stimulated AMs and to 35.1 ± 8.9 μM after a 24-h incubation, a near-maximum level. High levels of NO2−were produced by AMs primed with as little as 10 U of IFN-γ per ml in the presence ofP. carinii, and a 20-fold increase in IFN-γ concentration resulted in only a further 65% increase in NO2−production. RNI-dependent killing ofP. cariniiwas demonstrated by both a51Cr release assay and a [35S]methionine pulse immunoprecipitation assay. Addition of either monoclonal tumor necrosis factor alpha (TNF-α) neutralizing antibody or 200 μMNG-monomethyl-l-arginine (l-NGMMA), a competitive inhibitor of thel-arginine-dependent pathway, significantly decreased NO2−production and reducedP. cariniikilling. TNF-α alone had no effect onP. cariniiviability. These results suggest that (i) the specific interaction ofP. cariniiorganisms with IFN-γ-primed AMs triggers the production of RNI, (ii) RNI are toxic toP. carinii, and (iii) TNF-α likely plays a central role in mediatingP. cariniikilling by IFN-γ-stimulated AMs.
Neutralization of Endotoxin In Vitro and In Vivo by a Human Lactoferrin-Derived Peptide
Authors: Zhang Gui-Hang , Mann David M. , Tsai Chao-Ming 
Published: December 2019

ABSTRACTEndotoxin (lipopolysaccharide [LPS]) is the major pathogenic factor of gram-negative septic shock, and endotoxin-induced death is associated with the host overproduction of tumor necrosis factor alpha (TNF-α). In the search for new antiendotoxin molecules, we studied the endotoxin-neutralizing capacity of a human lactoferrin-derived 33-mer synthetic peptide (GRRRRSVQWCAVSQPEATKCFQWQRNMRKVRGP; designated LF-33) representing the minimal sequence for lactoferrin binding to glycosaminoglycans. LF-33 inhibited the coagulation of theLimulusamebocyte lysate and the secretion of TNF-α by RAW 264.7 cells induced by lipid A and four different endotoxins with a potency comparable to that of polymyxin B. The first six residues at the N terminus of LF-33 were critical for its antiendotoxin activity. The endotoxin-neutralizing capacity of LF-33 and polymyxin B was attenuated by human serum. Coinjection ofEscherichia coliLPS (125 ng) with LF-33 (2.5 μg) dramatically reduced the lethality of LPS in the galactosamine-sensitized mouse model. Significant protection of the mice against the lethal LPS challenge was also observed when LF-33 (100 μg) was given intravenously after intraperitoneal injection of LPS. Protection was correlated with a reduction in TNF-α levels in the mouse serum. These results demonstrate the endotoxin-neutralizing capability of LF-33 in vitro and in vivo and its potential use for the treatment of endotoxin-induced septic shock.
Clearance ofChlamydia trachomatisfrom the Murine Genital Mucosa Does Not Require Perforin-Mediated Cytolysis or Fas-Mediated Apoptosis
Authors: Perry Linda L. , Feilzer Karen , Hughes Scott , Caldwell Harlan D. 
Published: December 2019

ABSTRACTThe molecular mechanisms of resistance to genital infection with the mouse pneumonitis (MoPn) strain ofChlamydia trachomatisare unknown. A role for major histocompatibility complex class II-restricted, interleukin-12-dependent CD4+T cells has been established, but the functional activity of these cells does not depend on secretion of gamma interferon. Here we examined the potential contribution of T-cell-mediated cytotoxicity and apoptosis to mucosal clearance of MoPn by using mice deficient in the molecular mediators of target cell lysis. Animals lacking perforin, Fas, Fas ligand, or both perforin and Fas ligand were infected genitally withC. trachomatisMoPn and monitored for expression of immunity to chlamydial antigens and clearance of MoPn from the genital mucosa. In each case, the profile of spleen cytokine production, the magnitude of the host antibody response, and the kinetics of chlamydial clearance were similar to those of genetically intact controls. Compensatory overproduction of tumor necrosis factor alpha, an alternate mediator of apoptosis in certain cell types, did not appear to account for the ability of mutant mice to resolveChlamydiainfections. These results fail to support CD4+T-cell-mediated apoptosis or CD8+T-cell-mediated cytotoxicity as being critical to the clearance ofC. trachomatisMoPn urogenital infections.
Relationship between UDP-Glucose 4-Epimerase Activity and Oligoglucose Glycoforms in Two Strains of
Neisseria meningitidis
Authors: Lee Frank K. N. , Gibson Bradford W. , Melaugh William , Zaleski Anthony , Apicella Michael A. 
Published: December 2019

ABSTRACT

Sodium dodecyl sulfate-polyacrylamide gel analysis of lipooligosaccharide (LOS) from
Neisseria meningitidis
has demonstrated considerable microheterogeneity in the variable region of LOS due to the presence of novel glycoforms. As a step toward understanding the basis for the expression of these novel glycoforms, we have examined the LOS structures and UDP-glucose 4-epimerase (epimerase) activity levels in two strains (NMB and MA-1) and their respective
galE
mutants. Strain NMB was found to have low epimerase activity and to contain multiple glycoforms, some of which appear to contain only glucose sugars. The
galE
mutant had only the oligoglucose glycoforms. Strain MA-1 had higher epimerase activity at both log and stationary phases (2- and 12.5-fold, respectively) and one glycoform with a putative lactosyl structure. Strain MA-1
galE
had two glycoforms that contained one or two glucose residues. To understand the molecular basis for the different epimerase activities, we examined the predicted amino acid sequences of the respective
galE
open reading frames and determined the relative amounts of GalE protein. We found no significant differences between the predicted amino acid sequence of the GalE protein in NMB and that in MA-1. We observed no significant differences in the level of GalE protein between MA-1 and NMB at exponential or stationary phase. We also observed an 8.2-fold drop in epimerase activity in NMB between the log and stationary phases that was not due to the GalE protein level or low glucose levels.
Effect of Transforming Growth Factor β on ExperimentalSalmonella typhimuriumInfection in Mice
Authors: Galdiero Massimiliano , Marcatili Antonella , Cipollaro de l’ero Gabriella , Nuzzo Immacolata , Bentivoglio Concetta , Galdiero Marilena , Carratelli Caterina Romano 
Published: December 2019

ABSTRACTWe have investigated the effect of the in vivo administration of recombinant transforming growth factor β (rTGF-β) on the pathogenic mechanisms involved inSalmonella typhimuriumexperimental infection in mice. The protective response elicited by macrophages was induced by rTGF-β1by 2 days after experimental infection, as demonstrated by an increased NO production, while the humoral protective effect began with cytokine mRNA expression 2 days after the challenge and continued after 5 days with cytokine release and lymphocyte activation. We demonstrated that all mice who received rTGF-β1survived 7 days after infection. The number of bacteria recovered in the spleens and in the livers of rTGF-β1-treated mice 2 and 5 days after infection was significantly smaller than that found in the same organs after phosphate-buffered saline (PBS) inoculation. Furthermore, 2 and 5 days after infection, splenic macrophages from rTGF-β1-treated mice showed a greater NO production than did those from PBS-treated mice. The effect of rTGF-β1onS. typhimuriuminfection in mice was correlated with the expression of cell costimulatory CD28 molecules. Five days afterS. typhimuriuminfection, the percentage of CD28+-expressing T cells in splenic lymphocytes from rTGF-β1-treated mice increased with respect to that from control mice. Gamma interferon (IFN-γ) mRNA was present in a greater amount in spleen cells from rTGF-β1-treated mice after 2 days, although the intensity of the band decreased 5 days after the challenge. A similar pattern was obtained with the mRNAs for interleukin-1α (IL-1α), IL-6, TGF-β, and inducible nitric oxide synthase, which showed greater expression in cells obtained from rTGF-β1-treated andS. typhimurium-infected mice 2 days after challenge. The treatment with rTGF-β1induced an increase in IL-1α and IFN-γ release in the supernatant of splenocyte cultures 5 days after the experimental infection withS. typhimurium. Moreover, we demonstrated that 5 days after infection, the IFN-γ titer was significantly greater in the sera of rTGF-β-treated mice than in those of PBS-treated mice. Also, hsp60 showed greater expression 2 days after the challenge in splenocytes from rTGF-β1-treated mice. The role played by proinflammatory and immunoregulatory cytokines and by CD28 is discussed.
Safety and Immunogenicity of a
Pseudomonas aeruginosa
Hybrid Outer Membrane Protein F-I Vaccine in Human Volunteers
Authors: Mansouri Erfan , Gabelsberger Josef , Knapp Bernhard , Hundt Erika , Lenz Uwe , Hungerer Klaus-Dieter , Gilleland Harry E. , Staczek John , Domdey Horst , von Specht Bernd-Ulrich 
Published: December 2019

ABSTRACT

A hybrid protein [Met-Ala-(His)
6
OprF
190–342
-OprI
21–83
] consisting of the mature outer membrane protein I (OprI) and amino acids 190 to 342 of OprF of
Pseudomonas aeruginosa
was expressed in
Escherichia coli
and purified by Ni
2+
chelate-affinity chromatography. After safety and pyrogenicity evaluations in animals, four groups of eight adult human volunteers were vaccinated intramuscularly three times at 4-week intervals and revaccinated 6 months later with either 500, 100, 50, or 20 μg of OprF-OprI adsorbed onto A1(OH)
3
. All vaccinations were well tolerated. After the first vaccination, a significant rise of antibody titers against
P. aeruginosa
OprF and OprI was measured in volunteers receiving the 100- or the 500-μg dose. After the second vaccination, significant antibody titers were measured for all groups. Elevated antibody titers against OprF and OprI could still be measured 6 months after the third vaccination. The capacity of the elicited antibodies to promote complement binding and opsonization could be demonstrated by a C1q-binding assay and by the in vitro opsonophagocytic uptake of
P. aeruginosa
bacteria. These data support the continued development of an OprF-OprI vaccine for use in humans.
Probing the Function ofBordetella bronchisepticaAdenylate Cyclase Toxin by Manipulating Host Immunity
Authors: Harvill Eric T. , Cotter Peggy A. , Yuk Ming Huam , Miller Jeff F. 
Published: December 2019

ABSTRACTWe have examined the role of adenylate cyclase-hemolysin (CyaA) by constructing an in-frame deletion in theBordetella bronchiseptica cyaAstructural gene and comparing wild-type andcyaAdeletion strains in natural host infection models. Both the wild-type strain RB50 and its adenylate cyclase toxin deletion (ΔcyaA) derivative efficiently establish persistent infections in rabbits, rats, and mice following low-dose inoculation. In contrast, an inoculation protocol that seeds the lower respiratory tract revealed significant differences in bacterial numbers and in polymorphonuclear neutrophil recruitment in the lungs from days 5 to 12 postinoculation. We next explored the effects of disarming specific aspects of the immune system on the relative phenotypes of wild-type and ΔcyaAbacteria. SCID, SCID-beige, or RAG-1−/−mice succumbed to lethal systemic infection following high- or low-dose intranasal inoculation with the wild-type strain but not the ΔcyaAmutant. Mice rendered neutropenic by treatment with cyclophosphamide or by knockout mutation in the granulocyte colony-stimulating factor locus were highly susceptible to lethal infection by either wild-type or ΔcyaAstrains. These results reveal the significant role played by neutrophils early inB. bronchisepticainfection and by acquired immunity at later time points and suggest that phagocytic cells are a primary in vivo target of theBordetellaadenylate cyclase toxin.
Pseudomonas aeruginosa
Exoenzyme S Is a Biglutamic Acid ADP-Ribosyltransferase
Authors: Radke Jay , Pederson Kristin J. , Barbieri Joseph T. 
Published: December 2019

ABSTRACT

Kinetic analysis of two mutations within
Pseudomonas aeruginosa
exoenzyme S (ExoS) showed that a E379D mutation inhibited expression of ADP-ribosyltransferase activity but had little effect on the expression of NAD glycohydrolase activity while a E381D mutation inhibited expression of both activities. These data identify ExoS as a biglutamic acid ADP-ribosyltransferase, where E381 is the catalytic residue and E379 contributes to the transfer of ADP-ribose to the target protein.
Strains of
Actinomyces naeslundii
and
Actinomyces viscosus
Exhibit Structurally Variant Fimbrial Subunit Proteins and Bind to Different Peptide Motifs in Salivary Proteins
Authors: Li Tong , Johansson Ingegerd , Hay Donald I. , Strömberg Nicklas 
Published: December 2019

ABSTRACT

Oral strains of
Actinomyces
spp. express type 1 fimbriae, which are composed of major FimP subunits, and bind preferentially to salivary acidic proline-rich proteins (APRPs) or to statherin. We have mapped genetic differences in the
fimP
subunit genes and the peptide recognition motifs within the host proteins associated with these differential binding specificities. The
fimP
genes were amplified by PCR from
Actinomyces viscosus
ATCC 19246, with preferential binding to statherin, and from
Actinomyces naeslundii
LY7, P-1-K, and B-1-K, with preferential binding to APRPs. The
fimP
gene from the statherin-binding strain 19246 is novel and has about 80% nucleotide and amino acid sequence identity to the highly conserved
fimP
genes of the APRP-binding strains (about 98 to 99% sequence identity). The novel FimP protein contains an amino-terminal signal peptide, randomly distributed single-amino-acid substitutions, and structurally different segments and ends with a cell wall-anchoring and a membrane-spanning region. When agarose beads with CNBr-linked host determinant-specific decapeptides were used,
A. viscosus
19246 bound to the Thr
42
Phe
43
terminus of statherin and
A. naeslundii
LY7 bound to the Pro
149
Gln
150
termini of APRPs. Furthermore, while the APRP-binding
A. naeslundii
strains originate from the human mouth,
A. viscosus
strains isolated from the oral cavity of rat and hamster hosts showed preferential binding to statherin and contained the novel
fimP
gene. Thus,
A. viscosus
and
A. naeslundii
display structurally variant
fimP
genes whose protein products are likely to interact with different peptide motifs and to determine animal host tropism.
Role of Polymorphonuclear Neutrophils in a Murine Model ofChlamydia psittaci-Induced Abortion
Authors: Buendía Antonio J. , Montes de Oca Roberto , Navarro Jose A. , Sánchez Joaquín , Cuello Francisco , Salinas Jesús 
Published: December 2019

ABSTRACTTo assess the role of polymorphonuclear neutrophils (PMNs) inChlamydia psittaciinfection in a pregnant mouse model, pregnant and nonpregnant Swiss OF1 mice were depleted of PMNs by treatment with the RB6-8C5 monoclonal antibody before intraperitoneal infection withC. psittaciserotype 1. Nondepleted mice served as infection controls. Depleted mice aborted earlier and had a much higher mortality rate than nondepleted mice. Bacteriological analysis showed that the number of chlamydiae isolated from the spleens of depleted mice at 5 and 7 days postinfection was 100 times greater than that isolated from nondepleted mice. Histopathological analysis of the placentas of depleted mice showed widespread necrosis of the uteroplacental units, with weak immunoreaction to chlamydial antigen, while the placentas of nondepleted mice showed substantial neutrophil infiltration but no large areas of necrosis, with moderate to strong immunoreaction to chlamydial antigen. The livers of depleted mice showed numerous chlamydial inclusions in the hepatocytes, delayed microgranuloma formation, and in the pregnant animals extensive coagulative periportal necrosis. The livers of nondepleted mice displayed multiple small foci of PMNs and mononuclear cells with microgranuloma formation. Among this group of mice, the pregnant animals always had more hepatic damage than nonpregnant animals. Our results suggest that PMNs play an essential role in the response toC. psittaciprimary infection, preventing the uncontrolled multiplication of chlamydiae in the liver and spleen.
Bacterium-Dependent Induction of Cytokines in Mononuclear Cells and Their Pathologic Consequences In Vivo
Authors: Jiang Yanling , Magli Luciano , Russo Michael 
Published: December 2019

ABSTRACTViridans streptococci are a heterogeneous group of gram-positive bacteria that are normal inhabitants of the mouth. These organisms are thought to contribute significantly to the etiology of infective endocarditis, although recently they have been implicated in serious infections in other settings. Another group of oral bacteria, gram-negative anaerobes, is associated with chronic dental infections, such as periodontal diseases or endodontic lesion formation. We evaluated the ability of the oral pathogensStreptococcus mutansandPorphyromonas endodontalisto induce a pathogenic response in vivo, with the goal of quantifying the inflammatory response in soft tissue by measuring leukocyte recruitment and hard tissues by measuring osteoclastogenesis.S. mutansinduced a strong inflammatory response and was a potent inducer of osteoclast formation, whileP. endodontaliswas not. To further study the mechanisms by whichP. endodontalisandS. mutanselicit significantly different levels of inflammatory responses in vivo, we tested the capacity of each to induce production of cytokines by mononuclear cells in vitro.S. mutansstimulated high levels of interleukin-12 (IL-12), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α), all of which are associated with inflammation, enhanced monocyte function, and generation of a Th1 response. In contrast,P. endodontalisstimulated production of IL-10 but not of TNF-α, IL-12, or IFN-γ. These results demonstrate that oral pathogens differ dramatically in their abilities to induce inflammatory and immunoregulatory cytokines. Moreover, there is a high degree of correlation between the cytokine profile induced by these bacteria in vitro and their pathogenic capacity in vivo.
Levels of Antibody to Conserved Parts ofPlasmodium falciparumMerozoite Surface Protein 1 in Ghanaian Children Are Not Associated with Protection from Clinical Malaria
Authors: Dodoo Daniel , Theander Thor G. , Kurtzhals Jorgen A. L. , Koram Kojo , Riley Eleanor , Akanmori Bartholomew D. , Nkrumah Francis K. , Hviid Lars 
Published: December 2019

ABSTRACTThe 19-kDa conserved C-terminal part of thePlasmodium falciparummerozoite surface protein 1 (PfMSP119) is a malaria vaccine candidate antigen, and human antibody responses to PfMSP119have been associated with protection against clinical malaria. In this longitudinal study carried out in an area of stable but seasonal malaria transmission with an estimated parasite inoculation of about 20 infective bites/year, we monitored 266 3- to 15-year-old Ghanaian children clinically and parasitologically over a period of 18 months. Blood samples were collected at the beginning of the study before the major malaria season in April and after the season in November. Using enzyme-linked immunosorbent assay, we measured antibody responses to recombinant gluthathioneS-transferase–PfMSP119fusion proteins corresponding to the Wellcome and MAD20 allelic variants in these samples. Prevalence of antibodies recognizing the Wellcome 19 construct containing both epidermal growth factor (EGF)-like motifs in Wellcome type PfMSP119was about 30%. Prevalence of antibodies to constructs containing only the first EGF domain from either Wellcome or MAD20 type PfMSP119was about 15%, whereas antibodies recognizing a construct containing only the second EGF domain of MAD20 type PfMSP119was found in only about 4% of the donors. Neither the prevalence nor the levels of any of the antibody specificities varied significantly with season, age, or sex. Significantly, and in contrast to previous reports from other parts of West Africa, we found no evidence of an association between antibody responses to PfMSP119and clinical protection against malaria.
Immunization with Recombinant Transferrin Binding Protein B Enhances Clearance of Nontypeable
Haemophilus influenzae
from the Rat Lung
Authors: Webb Dianne C. , Cripps Allan W. 
Published: December 2019

ABSTRACT

Nontypeable
Haemophilus influenzae
(NTHI) is an opportunistic pathogen, and heterogeneity in the surface-exposed immunodominant domains of NTHI proteins is thought to be associated with the failure of an infection to stimulate an immune response that is cross-protective against heterologous NTHI strains. The aim of this study was to assess the vaccine potential of a surface-exposed component of the NTHI human transferrin receptor, TbpB, and to determine if the antibody response elicited was cross-reactive with heterologous strains of NTHI. The efficacy of immunization with a recombinant form of TbpB (rTbpB) was determined by assessing the pulmonary clearance of viable bacteria 4 h after a live challenge with NTHI. There was a significant reduction in the number of viable bacteria in both the bronchoalveolar lavage fluid (34% for the 20-μg dose and 58% for the 40-μg dose) and lung homogenates (26% for the 20-μg dose and 60% for the 40-μg dose) of rats immunized with rTbpB compared to the control animals. While rTbpB-specific antibodies from immunized rats were nonspecific in the recognition of TbpB from six heterologous NTHI strains on Western blots, these antibodies differed in their ability to block transferrin binding to heterologous strains and to cross-react in bactericidal assays. If bactericidal antibodies are key indicators of the efficacy of the immune response in eliminating NTHI, this data suggests that while immunization with rTbpB stimulates protective responses against the homologous isolate, variability in the recognition of TbpB from heterologous isolates may limit the potential of rTbpB as an NTHI vaccine component.