bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of Natural Killer Cells in Arthritis-Susceptible but Not Arthritis-Resistant Mouse Strains followingBorrelia burgdorferiInfection
Authors: Brown Charles R. , Reiner Steven L. 
Published: December 2019

ABSTRACTInfection of susceptible mouse strains withBorrelia burgdorferi, the agent of Lyme disease, results in the development of arthritis. Components of the innate immune system may be important mediators of this pathology. To investigate the potential role of NK cells in development of experimental Lyme arthritis, we examined their activation in vivo in both resistant and susceptible mouse strains. Following inoculation ofB. burgdorferiinto the footpad, lymph node NK cells from susceptible C3H/HeJ (C3H) mice produced more gamma interferon than NK cells from resistant DBA/2J mice. Lymph node cells from susceptible C3H and AKR mice also had increased ability to lyse YAC-1 target cells 2 days following infection. Antibody depletion of NK cells from susceptible mice, however, did not alter the development of arthritis followingB. burgdorferichallenge. In addition, NK cell depletion had little effect on spirochete burden. Thus, there is a marked activation of NK cells in susceptible mouse strains following infection. Although NK cells are not absolutely required for arthritis, events occurring prior to NK cell activation might be important in mediating pathology in experimental Lyme disease.
1,25-Dihydroxyvitamin D
3
Induces Nitric Oxide Synthase and Suppresses Growth of
Mycobacterium tuberculosis
in a Human Macrophage-Like Cell Line
Authors: Rockett Kirk A. , Brookes Roger , Udalova Irina , Vidal Vincent , Hill Adrian V. S. , Kwiatkowski Dominic 
Published: December 2019

ABSTRACT

Inducible synthesis of nitric oxide (NO) by macrophages is an important mechanism of the host defense against intracellular infection in mice, but the evidence for significant levels of inducible NO production by human macrophages is controversial. Here we report that the human promyelocytic cell line HL-60, when differentiated to a macrophage-like phenotype, acquires the ability to produce substantial amounts of NO on stimulation with LPS or 1,25-dihydroxyvitamin D
3
(1,25-D
3
) in the absence of activating factors such as gamma interferon. Expression of the inducible nitric oxide synthase (NOS2) was confirmed by sequencing of the reverse transcription-PCR product from stimulated HL-60 cells. Kinetic studies after lipopolysaccharide stimulation show that NOS2 mRNA levels rise within 3 to 6 h, that conversion of [
14
C]arginine to [
14
C]citrulline is maximal at 5 to 6 days, and that levels of reactive nitrogen intermediates stabilize at around 20 μM at 7 to 8 days. We find that 1,25-D
3
acts to suppress the growth of
Mycobacterium tuberculosis
in these cells and that this effect is inhibited by
N
G
-monomethyl-
l
-arginine, suggesting that vitamin D-induced NO production may play a role in the host defense against human tuberculosis.
Diversity of Antigen Recognition by Serum Antibodies in Experimental Bovine Tuberculosis
Authors: Lyashchenko Konstantin P. , Pollock John M. , Colangeli Roberto , Gennaro Maria Laura 
Published: December 2019

ABSTRACTTuberculosis in cattle remains a major zoonotic and economic problem in many countries. The standard diagnostic assay for bovine tuberculosis, the intradermal tuberculin test, has low accuracy. Therefore, alternative immunodiagnostic methods, such as serological assays, are needed for detection of infected animals. Development of an accurate serodiagnostic test requires a detailed understanding of the humoral immune responses during bovine tuberculosis and, in particular, identification of the key antigens ofMycobacterium bovisinvolved in antibody production. In this study, we characterized antibody responses in cattle experimentally infected withM. bovis. Sequential serum samples were collected every 3 to 4 weeks for up to 27 months postinfection. Circulating immunoglobulin G antibody levels were measured by an enzyme-linked immunosorbent assay using 12 highly purified recombinant proteins ofM. bovis. Six proteins, ESAT-6, 14-kDa protein, MPT63, MPT70, MPT51, and MPT32, were identified as major seroreactive antigens in bovine tuberculosis. A remarkable animal-to-animal variation of antigen recognition by serum antibodies was observed. Kinetic analyses of the antibody production to individual antigens during infection revealed that the heterogeneous antigen recognition profile changed markedly in a given infected animal as disease progressed.
Complement Activation in Relation to Capillary Leakage in Children with Septic Shock and Purpura
Authors: Hazelzet Jan A. , de Groot Ronald , van Mierlo Gerard , Joosten Koen F. M. , van der Voort Edwin , Eerenberg Anke , Suur Marja H. , Hop Wim C. J. , Hack C. Erik 
Published: December 2019

ABSTRACTTo assess the relationship between capillary leakage and inflammatory mediators during sepsis, blood samples were taken on hospital admission, as well as 24 and 72 h later, from 52 children (median age, 3.3 years) with severe meningococcal sepsis, of whom 38 survived and 14 died. Parameters related to cytokines (interleukin 6 [IL-6] IL-8, plasma phospholipase A2, and C-reactive protein [CRP]), to neutrophil degranulation (elastase and lactoferrin), to complement activation (C3a, C3b/c, C4b/c, and C3- and C4-CRP complexes), and to complement regulation (functional and inactivated C1 inhibitor and C4BP) were determined. The degree of capillary leakage was derived from the amount of plasma infused and the severity of disease by assessing the pediatric risk of mortality (PRISM) score. Levels of IL-6, IL-8, C3b/c, C3-CRP complexes, and C4BP on admission, adjusted for the duration of skin lesions, were significantly different in survivors and nonsurvivors (C3b/c levels were on average 2.2 times higher in nonsurvivors, and C3-CRP levels were 1.9 times higher in survivors). Mortality was independently related to the levels of C3b/c and C3-CRP complexes. In agreement with this, levels of complement activation products correlated well with the PRISM score or capillary leakage. Thus, these data show that complement activation in patients with severe meningococcal sepsis is associated with a poor outcome and a more severe disease course. Further studies should reveal whether complement activation may be a target for therapeutical intervention in this disease.
Gene Discovery through Expressed Sequence Tag Sequencing inTrypanosoma cruzi
Authors: Verdun Ramiro E. , Di Paolo Nelson , Urmenyi Turan P. , Rondinelli Edson , Frasch Alberto C. C. , Sanchez Daniel O. 
Published: December 2019

ABSTRACTAnalysis of expressed sequence tags (ESTs) constitutes a useful approach for gene identification that, in the case of human pathogens, might result in the identification of new targets for chemotherapy and vaccine development. As part of theTrypanosoma cruzigenome project, we have partially sequenced the 5′ ends of 1,949 clones to generate ESTs. The clones were randomly selected from a normalized CL Brener epimastigote cDNA library. A total of 14.6% of the clones were homologous to previously identifiedT. cruzigenes, while 18.4% had significant matches to genes from other organisms in the database. A total of 67% of the ESTs had no matches in the database, and thus, some of them might beT. cruzi-specific genes. Functional groups of those sequences with matches in the database were constructed according to their putative biological functions. The two largest categories were protein synthesis (23.3%) and cell surface molecules (10.8%). The information reported in this paper should be useful for researchers in the field to analyze genes and proteins of their own interest.
Impact of M49, Mrp, Enn, and C5a Peptidase Proteins on Colonization of the Mouse Oral Mucosa byStreptococcus pyogenes
Authors: Ji Yinduo , Schnitzler Norbert , DeMaster Eric , Cleary Patrick 
Published: December 2019

ABSTRACTResistance to phagocytosis is a hallmark of virulentStreptococcus pyogenes(group A streptococcus). Surface-bound C5a peptidase reduces recruitment of phagocytes to the site of infection, and hyaluronic acid capsules and/or the M protein limit the uptake of streptococci. In this study the relative impact of M and M-like proteins and the C5a peptidase on the virulence of a serotype M49 strain was assessed. The capacities of isogenic strains with an insertion mutation inemm49; with a deletion mutation inscpA49(C5a peptidase gene); and with a deletion that removes all three M-like genes,mrp49,emm49, andenn49, to colonize mice and resist phagocytosis were compared. Experiments confirmed results obtained in an earlier study, which showed that the M49 protein was not required for in vitro resistance to phagocytosis, and also showed that the M protein was not required for colonization of mice. Failure to produce all three M-like proteins, M49, Mrp, and Enn49, significantly reduced the ability of these streptococci to resist phagocytosis in vitro but did not significantly alter the persistence of streptococci on the oral mucosa. In vitro experiments indicate that M+streptococci are phagocytized by polymorphonuclear leukocytes that have been activated with phorbol-12-myristate 13-acetate or recombinant human C5a. This observation may explain the finding that expression of M49 protein is not essential for short-term colonization of the mouse oral mucosa.
Murine Immune Responses toNeisseria meningitidisGroup C Capsular Polysaccharide and a Thymus-Dependent Toxoid Conjugate Vaccine
Authors: Rubinstein Leonard J. , García-Ojeda Pablo A. , Michon Francis , Jennings Harold J. , Stein Kathryn E. 
Published: December 2019

ABSTRACTThe polysaccharide (PS) capsules of many pathogenic bacteria are poor immunogens in infants and young children as a result of the delayed response to PS antigens during ontogeny. The development of polysaccharide-protein conjugate vaccines forHaemophilus influenzaetype b, which have proven to be efficacious in this age group, has led to active development by a number of investigators of conjugate vaccines for other diseases. We describe here the response of several mouse strains to the capsular PS ofNeisseria meningitidisgroup C (MCPS) conjugated to tetanus toxoid (MCPS-TT) and the same response in BALB/c mice as a model of the immune consequences of conjugate vaccine immunization. The use of a conjugate vaccine results in a shift in the isotype elicited in response to the MCPS, from immunoglobulin M (IgM) and IgG3 to primarily IgG1. A response to MCPS-TT is seen even among mouse strains which respond poorly to MCPS itself, emphasizing the importance of a strain survey when choosing a mouse model for a vaccine. The marked increase in IgG1 antibody titer was accompanied by a large increase in bactericidal activity of sera from these animals. Animals primed with the conjugate vaccine demonstrated a booster response after secondary immunization with either the MCPS or the conjugate. The ability to produce a boosted IgG1 anti-MCPS response to the MCPS can be transferred to adoptive recipients by B cells alone from mice primed with MCPS-TT but not mice primed with MCPS alone. These data indicate that in BALB/c mice a single immunization with MCPS-TT is sufficient to induce a shift to IgG1 and generate a memory B-cell population that does not require T cells for boosting.
SCID/NCr Mice Naturally Infected with
Helicobacter hepaticus
Develop Progressive Hepatitis, Proliferative Typhlitis, and Colitis
Authors: Li Xiantang , Fox James G. , Whary Mark T. , Yan Lili , Shames Ben , Zhao Zhibao 
Published: December 2019

ABSTRACT

Hepatitis, proliferative typhlitis, and colitis were characterized in young adult and older SCID/NCr mice naturally infected with
Helicobacter hepaticus
. Liver lesions consisted of Kupffer, Ito, and oval cell hyperplasia along with multifocal to coalescing coagulative hepatocyte necrosis. Numerous Warthin-Starry-positive bacteria were observed in the parenchyma, and there were minimal to mild accumulations of monocytic cells and neutrophils. Proliferative typhlitis was characterized by moderate to marked mucosal epithelial cell hyperplasia with mild monocytic and neutrophilic infiltration. Minimal to mild colitis with mucosal epithelial cell hyperplasia of the colon was most marked in older mice. Comparable gastrointestinal lesions were not observed in uninfected control SCID/NCr mice.
H. hepaticus
was cultured from fetal viscera of 2 of 11 pups sampled late in gestation from infected SCID/NCr females, suggesting transplacental infection of
H. hepaticus
. As expected, most of the naturally infected SCID/NCr mice had no serum immunoglobulin G response against
H. hepaticus
. These findings contrast with those in infected immunocompetent A/JCr mice, which develop a significant immune response to
H. hepaticus
associated with prominent multifocal mononuclear cell infiltrates in the liver, with only rare bacteria observable at the periphery of inflammatory foci or in the biliary canaliculi. The results demonstrate that chronic inflammatory and proliferative lesions simultaneously affecting the liver, cecum, and colon are associated with natural infection of SCID/NCr mice with
H. hepaticus
and that lesions are progressive with age. Concurrent infection with
H. hepaticus
may confound studies that have been attributed to similar lesions due to other experimental manipulations of SCID/NCr mice.
Identification of the Perosamine Synthetase Gene ofBrucella melitensis16M and Involvement of Lipopolysaccharide O Side Chain inBrucellaSurvival in Mice and in Macrophages
Authors: Godfroid Fabrice , Taminiau Bernard , Danese Isabelle , Denoel Philippe , Tibor Anne , Weynants Vincent , Cloeckaert Axel , Godfroid Jacques , Letesson Jean-Jacques 
Published: December 2019

ABSTRACTBrucellaorganisms are facultative intracellular bacteria that may infect many species of animals as well as humans. The smooth lipopolysaccharide (S-LPS) has been reported to be an important virulence factor of these organisms, but the genetic basis of expression of the S-LPS O antigen has not yet been described. Likewise, the role of the O side chain of S-LPS in the survival ofBrucellahas not been clearly defined. A mini-Tn5transposon mutant library ofBrucella melitensis16M was screened by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies (MAbs) directed against the O side chain ofBrucella. One mutant, designated B3B2, failed to express any O side chain as confirmed by ELISA, Western blot analysis, and colony coloration with crystal violet. Nucleotide sequence analysis demonstrated that the transposon disrupted an open reading frame with significant homology to the putative perosamine synthetase genes ofVibrio choleraeO1 andEscherichia coliO157:H7. The low G+C content of this DNA region suggests that this gene may have originated from a species other than aBrucellasp. The survival ofB. melitensismutant strain B3B2 in the mouse model and in bovine macrophages was examined. The results suggested that S-LPS or, more precisely, its O side chain is essential for survival in mice but not in macrophages.
Nitric Oxide Synthase Expression in Macrophages ofHistoplasma capsulatum-Infected Mice Is Associated with Splenocyte Apoptosis and Unresponsiveness
Authors: Wu-Hsieh Betty A. , Chen Wen , Lee Hsin-Ju 
Published: December 2019

ABSTRACTSplenic macrophages fromHistoplasma capsulatum-infected mice express inducible nitric oxide synthase (iNOS), and the iNOS expression correlates with severity of the infection. We examined whether production of NO is responsible for apoptosis and the anti-lymphoproliferative response of splenocytes from mice infected withH. capsulatum. In situ terminal deoxynucleotidyl transferase nick end labeling revealed apoptotic nuclei in cryosections of spleen from infected but not normal mice. Splenocytes of infected mice were unresponsive to stimulation by either concanavalin A or heat-killedH. capsulatumyeast cells. Splenocyte responsiveness was restored by addition to the medium ofNG-monomethyl-l-arginine, a known inhibitor of NO production. The proliferative response of splenocytes from infected mice was also restored by depletion of macrophages or by replacement with macrophages from normal mice. In addition, expression of iNOS returned to its basal level when the animals had recovered from infection. These results suggest that suppressor cell activity of macrophages is associated with production of NO, which also appears to be an effector molecule for apoptosis of cultured splenocytes from infected mice.
Coxiella burnetiiInduces Reorganization of the Actin Cytoskeleton in Human Monocytes
Authors: Meconi Sonia , Jacomo Véronique , Boquet Patrice , Raoult Didier , Mege Jean-Louis , Capo Christian 
Published: December 2019

ABSTRACTCoxiella burnetii, an obligate intracellular bacterium which survives in myeloid cells, causes Q fever in humans. We previously demonstrated that virulentC. burnetiiorganisms are poorly internalized by monocytes compared to avirulent variants. We hypothesized that a differential mobilization of the actin cytoskeleton may account for this distinct phagocytic behavior. Scanning electron microscopy demonstrated that virulentC. burnetiistimulated profound and polymorphic changes in the morphology of THP-1 monocytes, consisting of membrane protrusions and polarized projections. These changes were transient, requiring 5 min to reach their maximum extent and vanishing after 60 min of incubation. In contrast, avirulent variants ofC. burnetiidid not induce any significant changes in cell morphology. The distribution of filamentous actin (F-actin) was then studied with a specific probe, bodipy phallacidin. VirulentC. burnetiiinduced a profound and transient reorganization of F-actin, accompanied by an increase in the F-actin content of THP-1 cells. F-actin was colocalized with myosin in cell protrusions, suggesting that actin polymerization and the tension of actin-myosin filaments play a role inC. burnetii-induced morphological changes. In addition, contact between the cell and the bacterium seems to be necessary to induce cytoskeleton reorganization. Bacterial supernatants did not stimulate actin remodeling, and virulentC. burnetiiorganisms were found in close apposition with F-actin protrusions. The manipulation of the actin cytoskeleton byC. burnetiimay therefore play a critical role in the internalization strategy of this bacterium.
Diversity in Protein Synthesis and Viability of
Helicobacter pylori
Coccoid Forms in Response to Various Stimuli
Authors: Mizoguchi Hiromoto , Fujioka Toshio , Kishi Kenji , Nishizono Akira , Kodama Reiji , Nasu Masaru 
Published: December 2019

ABSTRACT

The viability of the coccoid forms of
Helicobacter pylori
was evaluated by assessing protein synthesis. Metabolic labeling studies showed the synthesis of proteins and the specific protein profiles of
H. pylori
coccoids produced under various conditions. Harsh conditions such as aerobiosis and starvation (lack of horse serum) in the culture did not affect the synthesis of proteins in the coccoids. Lowering of the pH to that of gastric secretions induced expression of several proteins in the coccoids. However, the coccoids produced under prolonged microaerobic conditions exhibited a profile of acid stress-induced protein expression different from that induced by aerobiosis or starvation. Our data suggest that coccoid
H. pylori
exhibits diversity in viability following exposure to different stresses and that the response to acid stress of coccoid
H. pylori
could be involved in infection of the host stomach.
The Lipopolysaccharide of
Bordetella bronchiseptica
Acts as a Protective Shield against Antimicrobial Peptides
Authors: Banemann Andreas , Deppisch Heike , Gross Roy 
Published: December 2019

ABSTRACT

Resistance profiles of the two
Bordetella
species
B. bronchiseptica
and
B. pertussis
against various antimicrobial peptides were determined in liquid survival and agar diffusion assays.
B. bronchiseptica
exhibited significantly higher resistance against all tested peptides than
B. pertussis
. The most powerful agents acting on
B. bronchiseptica
were, in the order of their killing efficiencies, cecropin P > cecropin B > magainin-II-amide > protamine > melittin. Interestingly, for
B. bronchiseptica
, the resistance level was significantly affected by phase variation, as a
bvgS
deletion derivative showed an increased sensitivity to these peptides. Tn
5
-induced protamine-sensitive
B. bronchiseptica
mutants, which were found to be very susceptible to most of the cationic peptides, were isolated. In two of these mutants, the genetic loci inactivated by transposon insertion were identified as containing genes highly homologous to the
wlbA
and
wlbL
genes of
B. pertussis
that are involved in the biosynthesis of lipopolysaccharide (LPS). In agreement with this finding, the two peptide-sensitive mutants revealed structural changes in the LPS, resulting in the loss of the O-specific side chains and the prevalence of the LPS core structure. This demonstrates that LPS plays a major role in the resistance of
B. bronchiseptica
against the action of antimicrobial peptides and suggests that
B. pertussis
is much more susceptible to these peptides due to the lack of the highly charged O-specific sugar side chains.
Systemic and Mucosal Immune Responses after Intranasal Administration of RecombinantMycobacterium bovisBacillus Calmette-Guérin Expressing GlutathioneS-Transferase fromSchistosoma haematobium
Authors: Kremer Laurent , Dupré Loïc , Riveau Gilles , Capron André , Locht Camille 
Published: December 2019

ABSTRACTA major goal of current vaccine development is the induction of strong immune responses against protective antigens delivered by mucosal routes. One of the most promising approaches in that respect relies on the use of live recombinant vaccine carriers. In this study,Mycobacterium bovisBCG was engineered to produce an intracellular glutathioneS-transferase fromSchistosoma haematobium(Sh28GST). The gene encoding Sh28GST was placed under the control of the mycobacterialhsp60promoter on a replicative shuttle plasmid containing a mercury resistance operon as the only selectable marker. The recombinant Sh28GST produced in BCG bound glutathione and expressed enzymatic activity, indicating that its active site was properly folded. Both intraperitoneal and intranasal immunizations of BALB/c mice with the recombinant BCG resulted in strong anti-Sh28GST antibody responses, which were enhanced by a boost. Mice immunized intranasally produced a mixed response with the production of Sh28GST-specific immunoglobulin G1 (IgG1), IgG2a, IgG2b, and IgA in the serum. In addition, high levels of anti-Sh28GST IgA were also found in the bronchoalveolar lavage fluids, demonstrating that intranasal delivery of the recombinant BCG was able to induce long-lasting secretory and systemic immune responses to antigens expressed intracellularly. Surprisingly, intranasal immunization with the BCG producing the Sh28GST induced a much stronger specific humoral response than intranasal immunization with BCG producing the glutathioneS-transferase fromSchistosoma mansoni, although the two antigens have over 90% identity. This difference was not observed after intraperitoneal administration.