bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reciprocal Regulation of Th1- and Th2-Cytokine-Producing T Cells during Clearance of Parasitemia inPlasmodium falciparumMalaria
Authors: Winkler Stefan , Willheim Martin , Baier Karin , Schmid Daniela , Aichelburg Alexander , Graninger Wolfgang , Kremsner Peter G. 
Published: December 2019

ABSTRACTFlow cytometry for the intracellular detection of T-cell cytokines was performed for 15 Gabonese patients during acute uncomplicatedPlasmodium falciparummalaria. A striking expansion of CD4+and CD8+T cells producing gamma interferon (IFN-γ) was found during drug-induced clearance of parasitemia, paralleled by a decrease of interleukin-2 (IL-2) production. The frequency of IL-4- and IL-13-producing CD4+cells gradually decreased, whereas the frequency of T cells producing IL-2+–IFN-γ+, IL-4−–IL-5+, and IL-4+–IL-5+cytokines as well as IL-4+–IFN-γ+and IL-13+–IFN-γ+cytokines was not significantly altered. The capacity for IL-10 production within the CD4+subset increased due to an expansion of both IL-10+–IFN-γ−and IL-10+–IFN-γ+cytokine-expressing cells. Thus, a more pronounced Th2-driven immune response during acute untreatedP. falciparuminfection with a shift towards Th1 responsiveness induced by parasite clearance is suggested.
Changes in Expression of Signal Transduction Proteins in T Lymphocytes of Patients with Leprosy
Authors: Zea Arnold H. , Ochoa Maria T. , Ghosh Paritosh , Longo Dan L. , Alvord W. Gregory , Valderrama Liliana , Falabella Rafael , Harvey Linda K. , Saravia Nancy , Moreno Luis H. , Ochoa Augusto C. 
Published: December 2019

ABSTRACTAdvanced stages of mycobacterial diseases such as leprosy and tuberculosis are characterized by a loss of T-cell function. The basis of this T-cell dysfunction is not well understood. The present report demonstrates major alterations in the expression of signal transduction molecules in T cells of leprosy patients. These alterations were most frequently observed in lepromatous leprosy (LL) patients. Of 29 LL patients, 69% had decreased T-cell receptor ζ-chain expression, 48% had decreased p56lcktyrosine kinase, and 63% had a loss of nuclear transcription factor NF-κB p65. An electrophoretic mobility shift assay with the gamma interferon core promoter region revealed a loss of the Th1 DNA-binding pattern in LL patients. In contrast, tuberculoid leprosy patients had only minor signal transduction alterations. These novel findings might improve our understanding of the T-cell dysfunction observed in leprosy and other infectious diseases and consequently might lead to better immunologic evaluation of patients.
Intracellular Multiplication and Virulence of
Shigella flexneri
Auxotrophic Mutants
Authors: Cersini Antonella , Salvia Anna Maria , Bernardini Maria Lina 
Published: December 2019

ABSTRACT

We have constructed and analyzed a group of
Shigella flexneri
5 auxotrophic mutants. The wild-type strain M90T was mutagenized in genes encoding enzymes involved in the synthesis of (i) aromatic amino acids, (ii) nucleotides, and (iii) diaminopimelic acid. In this way, strains with single (
aroB
,
aroC
,
aroD
,
purE
,
thyA
, and
dapB
) and double (
purE aroB
,
purE aroC
,
purE aroD
,
purE thyA
) mutations were obtained. Although the Aro mutants had the same nutritional requirements when grown in laboratory media, they showed different degrees of virulence in vitro and in vivo. The
aroB
mutant was not significantly attenuated, whereas both the
aroC
and
aroD
strains were severely attenuated.
p
-Aminobenzoic acid (PABA) appeared to be the main requirement for the Aro mutants’ growth in tissue culture. Concerning nucleotides, thymine reduced the pathogenicity, whereas adenine did not. However, when combined with another virulence-affecting mutation, adenine auxotrophy appeared to potentiate that mutation’s effects. Consequently, the association of either the
purE
and
aroC
or the
purE
and
aroD
mutations had a great effect on virulence as measured by the Sereny test, whereas the
purE aroB
double mutation appeared to have only a small effect. All mutants except the
dapB
strain seemed to move within a Caco-2 cell monolayer after 3 h of infection. Nevertheless, the auxotrophs showing a high intracellular generation time were negative in the plaque assay. Knowledge of each mutation’s role in attenuating
Shigella
strains will provide useful tools in designing vaccine candidates.
Nitric Oxide-Mediated Inhibition of the Ability ofRickettsia prowazekiiTo Infect Mouse Fibroblasts and Mouse Macrophagelike Cells
Authors: Turco Jenifer , Liu Hua , Gottlieb Sheldon F. , Winkler Herbert H. 
Published: December 2019

ABSTRACTThe role of the nitric oxide synthase (NOS) pathway in inhibiting the ability ofRickettsia prowazekiito initially infect (invade) mouse cytokine-treated, fibroblastic L929 cells and macrophagelike RAW264.7 cells and the ability of nitric oxide (NO) to damage isolated rickettsiae were investigated. Substantial amounts of nitrite (a degradation product of NO) were produced and the initial rickettsial infection was suppressed in cultures of L929 cells treated with crude lymphokine preparations (LK) or with gamma interferon (IFN-γ) plus tumor necrosis factor alpha (TNF-α) but not in L929 cell cultures treated with IFN-γ alone or TNF-α alone. The NOS inhibitorsNG-methyl-l-arginine and aminoguanidine both inhibited nitrite production and prevented the suppression of the initial rickettsial infection. Antibody-mediated neutralization of the IFN-γ in the LK also inhibited both nitrite production and suppression of the initial rickettsial infection. Cultures of RAW264.7 cells treated with IFN-γ plus lipopolysaccharide exhibited suppression of the initial rickettsial infection, and the suppression was relieved by aminoguanidine. Addition of oxyhemoglobin (a scavenger of extracellular NO) during the rickettsial infection alleviated the suppression of the initial rickettsial infection observed in appropriately treated L929 cells and RAW264.7 cells. In addition, the oxyhemoglobin restored the rickettsia-mediated, rapid killing of the treated RAW264.7 cells. Incubation of isolated rickettsiae with NO inhibited their ability to infect L929 and IFN-γ-treated RAW264.7 cells and to rapidly kill IFN-γ-treated RAW264.7 cells. In contrast, incubation of L929 cells with a solution that contained NO and/or degradation products of NO did not affect their ability to be infected by rickettsiae. The data are consistent with the hypothesis that NO released from appropriately stimulated potential host cells kills extracellular rickettsiae and thus prevents the rickettsiae from infecting the cells.
A Murine Model in Which Protection Correlates with Pertussis Vaccine Efficacy in Children Reveals Complementary Roles for Humoral and Cell-Mediated Immunity in Protection againstBordetella pertussis
Authors: Mills Kingston H. G. , Ryan Mark , Ryan Elizabeth , Mahon Bernard P. 
Published: December 2019

ABSTRACTThe results of phase 3 efficacy trials have shown that acellular and whole-cell pertussis vaccines can confer protection against whooping cough. However, despite the advances in vaccine development, clinical trials have not provided significant new information on the mechanism of protective immunity againstBordetella pertussis. Classical approaches based on measurement of antibody responses to individual antigens failed to define an immunological correlate of protection. A reliable animal model, predictive of acellular and whole-cell pertussis vaccine potency in children, would facilitate an elucidation of the mechanism of immune protection againstB. pertussisand would assist in the regulatory control and future development of pertussis vaccines. In this study, we have shown that the rate ofB. pertussisclearance following respiratory challenge of immunized mice correlated with vaccine efficacy in children. Using this model together with mice with targeted disruptions of the gamma interferon (IFN-γ) receptor, interleukin-4 or immunoglobulin heavy-chain genes, we have demonstrated an absolute requirement for B cells or their products in bacterial clearance and a role for IFN-γ in immunity generated by previous infection or immunization with the whole-cell pertussis vaccine. The results of passive immunization experiments suggested that protection early after immunization with acellular pertussis vaccines is mediated by antibody against multiple protective antigens. In contrast, more complete protection conferred by previous infection or immunization with whole-cell pertussis vaccines reflected the induction of Th1 cells. Our findings suggest that the mechanism of immunity againstB. pertussisinvolves humoral and cellular immune responses which are not directed against a single protective antigen and thus provide an explanation for previous failures to define an immunological correlate of protection.
Effect of Lipopolysaccharide and Inflammatory Cytokines on Interleukin-6 Production by Healthy Human Gingival Fibroblasts
Authors: Kent Leigh W. , Rahemtulla Firoz , Hockett Richard D. , Gilleland Rebecca C. , Michalek Suzanne M. 
Published: December 2019

ABSTRACTCytokines are hormone-like proteins which mediate and regulate inflammatory and immune responses. The purpose of this study was to investigate the effect of lipopolysaccharide (LPS) and inflammatory cytokines on regulation of interleukin-6 (IL-6) production by human gingival fibroblasts (HGF). The HGF cell lines used in this study, H-CL and F-CL, were established by the explant technique from healthy gingival tissue. Cultured cells were grown to confluency and incubated with various concentrations of LPS fromEscherichia coliorPorphyromonas gingivalisor with the recombinant human cytokine tumor necrosis factor alpha (TNF-α), IL-1α, or IL-1β. Culture supernatants were collected at various times and assessed for IL-6 production by enzyme-linked immunosorbent assay. Total RNA was isolated from the harvested cells and used to assess levels of IL-6 mRNA by the RNase protection assay. Both LPS preparations induced IL-6 production (1 to 4 ng of IL-6 per ml) by both HGF cell lines. Although TNF-α stimulated IL-6 production by HGF, >10-fold-larger amounts were induced with IL-1α and IL-1β. Furthermore, the addition of both IL-1α and TNF-α to cultured cells resulted in approximately 600- to 800-fold-higher levels of IL-6 than seen in control cultures, suggesting that these cytokines synergistically induced IL-6 production by HGF. IL-6 message in cultured cells was upregulated 20-fold by TNF-α, 1,000-fold by IL-1α and IL-1β, and 1,400-fold by IL-1α plus TNF-α. IL-1α and TNF-α alone upregulate IL-6 production in a dose- and time-dependent fashion. The addition of IL-1α and TNF-α to cultured HGF cells resulted in a synergistic induction of IL-6 after 8 h of incubation and when greater than 10 pg of this combination per ml was used. Our studies show that inflammatory cytokines are hundreds of times more potent than LPS in stimulating IL-6 production by HGF.
Polymorphism in the
Bordetella pertussis
Virulence Factors P.69/Pertactin and Pertussis Toxin in The Netherlands: Temporal Trends and Evidence for Vaccine-Driven Evolution
Authors: Mooi Frits R. , van Oirschot Hans , Heuvelman Kees , van der Heide Han G. J. , Gaastra Wim , Willems Rob J. L. 
Published: December 2019

ABSTRACT

The
Bordetella pertussis
proteins P.69 (also designated pertactin) and pertussis toxin are important virulence factors and have been shown to confer protective immunity in animals and humans. Both proteins are used in the new generation of acellular pertussis vaccines (ACVs), and it is therefore important to study the degree of antigenic variation in these proteins. Sequence analysis of the genes for P.69 and the pertussis toxin S1 subunit, using strains collected from Dutch patients in the period 1949 to 1996, revealed three P.69 and three S1 variants which show differences in amino acid sequence. Polymorphism in P.69 was confined to a region comprised of repeats and located proximal to the RGD motif involved in adherence to host tissues. Variation in S1 was observed in two regions previously identified as T-cell epitopes. P.69 and S1 variants, identical to those included in the Dutch whole-cell pertussis vaccine (WCV), were found in 100% of the strains from the 1950s, the period when the WCV was introduced in The Netherlands. However, nonvaccine types of P.69 and S1 gradually replaced the vaccine types in later years and were found in ∼90% strains from 1990 to 1996. These results suggest that vaccination has selected for strains which are antigenically distinct from vaccine strains. Analysis of strains from vaccinated and nonvaccinated individuals indicated that the WCV protects better against strains with the vaccine type P.69 than against strains with non-vaccine types (
P
= 0.024). ACVs contain P.69 and S1 types which are found in only 10% of recent Dutch
B. pertussis
isolates, implying that they do not have an optimal composition. Our findings cast a new light on the reemergence of pertussis in highly vaccinated populations and may have major implications for the long-term efficacy of both WCVs and ACVs.
Secretory Immune Response to Membrane Antigens duringGiardia lambliaInfection in Humans
Authors: Rosales-Borjas Disney M. , Díaz-Rivadeneyra Juan , Doña-Leyva Antonio , Zambrano-Villa Sergio A. , Mascaró Carmen , Osuna Antonio , Ortiz-Ortiz Librado 
Published: December 2019

ABSTRACTThe secretory immune response in humans infected withGiardia lambliawas studied by using saliva samples and a membrane-rich protein fraction. The membrane fraction, studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, showed 24 antigen bands, ranging from 170 to 14 kDa. Saliva samples from giardiasis patients showed a heterogeneous response against the membrane fraction when they were assayed by immunoblotting. Among the antigens recognized by patient saliva samples, those of 170, 105, 92, 66, 32, 29, and 14 kDa stood out. These antigens were not recognized by saliva samples from healthy individuals. They may be of importance in future studies of protection from or diagnosis ofG. lambliainfections.
Genetic Inactivation of an Extracellular Cysteine Protease (SpeB) Expressed byStreptococcus pyogenesDecreases Resistance to Phagocytosis and Dissemination to Organs
Authors: Lukomski Slawomir , Burns Eugene H. , Wyde Philip R. , Podbielski Andreas , Rurangirwa Jacqueline , Moore-Poveda Donna K. , Musser James M. 
Published: December 2019

ABSTRACTStreptococcal pyrogenic exotoxin B (SpeB), a conserved cysteine protease expressed by virtually allStreptococcus pyogenesstrains, has recently been shown to be an important virulence factor (S. Lukomski, S. Sreevatsan, C. Amberg, W. Reichardt, M. Woischnik, A. Podbielski, and J. M. Musser, J. Clin. Invest. 99:2574–2580, 1997). Genetic inactivation of SpeB significantly decreased the lethality of a serotype M49 strain for mice and abolished the lethality of a serotype M3 strain after intraperitoneal (i.p.) injection. In the present study, a wild-type M3 isolate and an M3speBmutant derivative were used to investigate the mechanism responsible for altered virulence. Following i.p. injection, the mutant and wild-type strains induced virtually identical cellular inflammatory responses, characterized largely by an influx of polymorphonuclear leukocytes (PMNs). In addition, the mutant and wild-type strains rapidly entered the blood and were recovered from all organs examined. However, significantly fewer (P< 0.05) CFUs of the isogenic mutant derivative than of the wild-type parent strain were recovered from blood and organs. PMNs effectively cleared the M3speBmutant from the peritoneum by 22 h, thereby sparing the host. In contrast, the wild-type M3 strain continued to replicate intraperitoneally and had the ability to kill phagocytes. This process allowed the wild-type strain to continuously disseminate, resulting in host death. Our results indicate that genetic inactivation of the cysteine protease decreased the resistance of the mutant to phagocytosis and impaired its subsequent dissemination to organs. These results provide insight into the detrimental effect of SpeB inactivation on virulence.
In Vivo Formation of Electron Paramagnetic Resonance-Detectable Nitric Oxide and of Nitrotyrosine Is Not Impaired during Murine Leishmaniasis
Authors: Giorgio Selma , Linares Edlaine , Ischiropoulos Harry , Von Zuben Fernando José , Yamada Aureo , Augusto Ohara 
Published: December 2019

ABSTRACTRecent studies have provided evidence for a dual role of nitric oxide (NO) during murine leishmaniasis. To explore this problem, we monitored the formation of NO and its derived oxidants during the course ofLeishmania amazonensisinfection in tissues of susceptible (BALB/c) and relatively resistant (C57BL/6) mice. NO production was detected directly by low-temperature electron paramagnetic resonance spectra of animal tissues. Both mouse strains presented detectable levels of hemoglobin nitrosyl (HbNO) complexes and of heme nitrosyl and iron-dithiol-dinitrosyl complexes in the blood and footpad lesions, respectively. Estimation of the nitrosyl complex levels demonstrated that most of the NO is synthesized in the footpad lesions. In agreement, immunohistochemical analysis of the lesions demonstrated the presence of nitrotyrosine in proteins of macrophage vacuoles and parasites. Since macrophages lack myeloperoxidase, peroxynitrite is likely to be the nitrating NO metabolite produced during the infection. The levels of HbNO complexes in the blood reflected changes occurring during the infection such as those in parasite burden and lesion size. The maximum levels of HbNO complexes detected in the blood of susceptible mice were higher than those of C57BL/6 mice but occurred at late stages of infection and were accompanied by the presence of bacteria in the cutaneous lesions. The results indicate that the local production of NO is an important mechanism for the elimination of parasites if it occurs before the parasite burden becomes too high. From then on, elevated production of NO and derived oxidants aggravates the inflammatory process with the occurrence of a hypoxic environment that may favor secondary infections.
Inducible Nitric Oxide Synthase Does Not Affect Resolution of Murine Chlamydial Genital Tract Infections or Eradication of Chlamydiae in Primary Murine Cell Culture
Authors: Ramsey Kyle H. , Miranpuri Gurwattan S. , Poulsen Christoffer E. , Marthakis Nancy B. , Braune Laima M. , Byrne Gerald I. 
Published: December 2019

ABSTRACTMice lacking inducible nitric oxide synthase (iNOS) or treated with iNOS inhibitors resolved chlamydial genital tract infections. Additionally, treatment of primary murine cell cultures with gamma interferon restricted chlamydial growth in the absence of nitric oxide. From these results, iNOS activity is unnecessary for the resolution of chlamydial genital tract infections in mice and inhibition of chlamydial growth in culture.
Anti-Lipid A Monoclonal Antibody Centoxin (HA-1A) Binds to a Wide Variety of Hydrophobic Ligands
Authors: Helmerhorst E. J. , Maaskant J. J. , Appelmelk B. J. 
Published: December 2019

ABSTRACTThis note describes the binding specificities of four lipid A monoclonal antibodies (MAbs) including Centoxin (HA-1A); these MAbs display similar binding properties. MAbs reacted with lipid A and heat-killed smooth bacteria, whereas no reactivity was observed with smooth lipopolysaccharide (LPS). Immunoblotting of bacterial extracts separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the MAbs bound to many polypeptide bands including the molecular weight markers. Denaturation of bovine serum albumin (BSA) by boiling or dithiothreitol treatment unmasked antibody epitopes. In addition, binding both to a hydrophobic aliphatic C12 chain covalently coupled to BSA and to single-stranded DNA was observed. The polyreactivity of these clones is most likely mediated by a preferential reactivity with hydrophobic molecular patches.
Transposon-Derived
Brucella abortus
Rough Mutants Are Attenuated and Exhibit Reduced Intracellular Survival
Authors: Allen Chris A. , Adams L. Garry , Ficht Thomas A. 
Published: December 2019

ABSTRACT

The O antigen of
Brucella abortus
has been described as a major virulence determinant based on the attenuated survival of fortuitously isolated rough variants. However, the lack of genetic definition of these mutants and the virulence of naturally occurring rough species,
Brucella ovis
and
Brucella canis
, has confused interpretation. To better characterize the role of O antigen in virulence and survival, transposon mutagenesis was used to generate
B. abortus
rough mutants defective in O-antigen presentation. Sequence analysis of DNA flanking the site of Tn
5
insertion was used to verify insertion in genes encoding lipopolysaccharide (LPS) biosynthetic functions. Not surprisingly, each of the rough mutants was attenuated for survival in mice, but unexpected differences among the mutants were observed. In an effort to define the basis for the observed differences, the structure of the rough LPS and the sensitivity of these mutants to individual killing mechanisms were examined in vitro. All of the
B. abortus
rough mutants exhibited a 4- to 5-log-unit increase, compared to the smooth parental strain, in sensitivity to complement-mediated lysis. Little change was evident in the sensitivity of these organisms to hydrogen peroxide, consistent with an inability of O antigen to exclude relatively small molecules. Sensitivity to polymyxin B, which was employed as a model cationic, amphipathic peptide similar to defensins found in phagocytic cells, revealed survival differences among the rough mutants similar to those observed in the mouse. One mutant in particular exhibited hypersensitivity to polymyxin B and reduced survival in mice. This mutant was characterized by a truncated rough LPS. DNA sequence analysis of this mutant revealed a transposon interruption in the gene encoding phosphomannomutase (
pmm
), suggesting that this activity may be required for the synthesis of a full-length core polysaccharide in addition to O antigen.
B. abortus
O antigen appears to be essential for extra- and intracellular survival in mice.
Evidence for Specific Secretion Rather than Autolysis in the Release of Some
Helicobacter pylori
Proteins
Authors: Vanet Anne , Labigne Agnès 
Published: December 2019

ABSTRACT

We investigated whether
Helicobacter pylori
cells actively secrete proteins such as the urease subunits UreA and UreB and the GroES and GroEL homologs HspA and HspB or whether these proteins were present in the extracellular compartment as a consequence of autolysis. Using a subcellular fractionation approach associated with quantitative Western blot analyses, we showed that the supernatant protein profiles were very different from those of the cell pellets, even for bacteria harvested in the late growth phase; this suggests that the release process is selective. A typical cytoplasmic protein, a β-galactosidase homolog, was found exclusively associated with the pellet of whole-cell extracts, and no traces were found in the supernatant. In contrast, UreA, UreB, HspA, and HspB were mostly found in the pellet but significant amounts were also present in the supernatant. HspA and UreB were released into the supernatant at the same rate throughout the growth phase (3%), whereas large portions of HspB and UreA were released during the stationary phase (over 30 and 20%, respectively) rather than during the early growth phase (20% and 6, respectively). The profiles of protein obtained after water extraction of the bacteria with those of the proteins naturally released within the liquid culture supernatants demonstrated that water extraction led to the release of a large amount of protein due to artifactual lysis. Our data support the conclusion that a specific and selective mechanism(s) is involved in the secretion of some
H. pylori
antigens. A programmed autolysis process does not seem to make a major contribution.