bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential Expression ofVibrio vulnificusCapsular Polysaccharide
Authors: Wright Anita C. , Powell Jan L. , Tanner Mike K. , Ensor Lynne A. , Karpas Arthur B. , Morris J. Glenn , Sztein Marcelo B.
Published: December 2019

Vibrio vulnificusis a human pathogen whose virulence has been associated with the expression of capsular polysaccharide (CPS). Multiple CPS types have been described; however, virulence does not appear to correlate with a particular CPS composition. Reversible-phase variation for opaque and translucent colony morphologies is characterized by changes in CPS expression, as suggested by electron microscopy of cells stained nonspecifically with ruthenium red. Isolates with opaque colony morphologies are virulent and appear to be more thickly encapsulated than naturally occurring translucent-phase variants, which have reduced, patchy, or absent CPS. Previously, we have shown that the virulence of translucent-phase variants was intermediate between opaque-phase variants and acapsular transposon mutants, suggesting a correlation between virulence and the amount of CPS expressed. In the present study, CPS expression of phase variants and genetically defined mutants ofV. vulnificusM06-24/O was examined by using a CPS-specific monoclonal antibody with an enzyme-linked immunosorbent assay, flow cytometry, and immunoelectron microscopy. Semiquantitative analyses of CPS expression correlated well among these assays, confirming that the translucent-phase variant was intermediate in CPS expression and retained type I CPS-specific epitopes. Cell surface expression of CPS varied with the growth phase, increasing during logarithmic growth and declining in stationary culture. Significantly greater CPS expression (P= 0.026) was observed for cells grown at 30°C than for those at 37°C. These studies confirm that phase variation and virulence inV. vulnificuscorrelate with the amount of CPS expressed and demonstrate the fluidity of bacterial polysaccharide expression in response to environmental conditions.
Antibacterial Action of Extracellular Mammalian Group IIA Phospholipase A2 against Grossly Clumped
Staphylococcus aureus
Authors: Dominiecki Mary E. , Weiss Jerrold
Published: December 2019

Fibrinogen-dependent interactions of
Staphylococcus aureus
are believed to contribute to bacterial virulence by promoting bacterial attachment to fibrinogen-coated surfaces and inducing the formation of bacterial clumps that are likely resistant to phagocytosis. Although
S. aureus
produces several fibrinogen-binding proteins, the cell wall-associated protein clumping factor (encoded by
clfA
) appears to be most important in bacterial interactions with immobilized or soluble purified fibrinogen. We have compared bacterial clumping in several strains of
S. aureus
, including isogenic ClfA
+
and ClfA
−
Newman strains, in the presence of purified rabbit fibrinogen, human plasma, and inflammatory fluid and examined the effect of clumping on bacterial sensitivity to mammalian group IIA phospholipase A2 (PLA2). This enzyme is the major extracellular bactericidal agent in inflammatory fluid active against
S. aureus
. Both ClfA-dependent and ClfA-independent bacterial clumping was observed, depending on the source and fibrinogen content of the biological fluid. In each case, clumping only partially reduced the antibacterial activity of PLA2, suggesting that this extracellular enzyme can substantially penetrate dense bacterial clumps. Bacterial clumps could be dispersed by added proteases, restoring full antibacterial activity to PLA2. Thus, the extracellular mobilization of group IIA PLA2 during inflammation may provide a mechanism by which the host can control the proliferation and survival of
S. aureus
even after bacterial clumping.
Interleukin-12 as an Adjuvant for an Antischistosome Vaccine Consisting of Adult Worm Antigens: Protection of Rats from Cercarial Challenge
Authors: Bungiro Richard D. , Goldberg Miriam , Suri Parmjeet K. , Knopf Paul M.
Published: December 2019

Our group previously demonstrated that a detergent extract (fraction S3) prepared from immature (4-week)Schistosoma mansoniparasites can induce partial, serum-transferable immunity to challenge infection in rats when administered as an alum precipitate. In the present study, we examined whether S3 prepared from adult (7-week) worms could similarly induce protection and whether immunity could be positively influenced by treatment with interleukin-12 (IL-12). IL-12 coadministered to Fischer rats and C57BL/6 mice at the time of S3 vaccination altered the prechallenge kinetics of S3-specific antibody titers in both species, ultimately leading to a stable enhancement of titers (relative to those in animals vaccinated without IL-12) in mice but not rats. Immunoblot analysis of prechallenge immune sera demonstrated that IL-12 treatment was associated with changes in the S3 antigen recognition profile in each species. Isotyping of specific antibodies in S3- plus IL-12-vaccinated mice prior to challenge infection revealed a moderate elevation in immunoglobulin G1 (IgG1) responses, strongly enhanced IgG2a and IgG2b responses, as well as diminished total serum IgE responses compared to those in mice given S3 only. In vaccinated rats, IL-12 profoundly suppressed specific IgG1 and enhanced IgG2b responses but did not affect IgG2a responses. S3- plus IL-12-vaccinated rats also produced less total IgE upon challenge infection. Enumeration of worm burdens revealed that vaccination with S3 plus IL-12 conferred 50% protection from cercarial challenge to rats, whereas rats given S3 only were not protected; mice were not protected by S3 vaccination regardless of IL-12 coadministration. The protection observed in S3- plus IL-12-vaccinated rats could not be transferred with serum, suggesting participation of an activated cellular component in the expression of immunity.
Gamma Interferon Production Is Critical for Protective Immunity to Infection with Blood-StagePlasmodium bergheiXAT but Neither NO Production nor NK Cell Activation Is Critical
Authors: Yoneto Toshihiko , Yoshimoto Takayuki , Wang Chrong-Reen , Takahama Yasuhiro , Tsuji Moriya , Waki Seiji , Nariuchi Hideo
Published: December 2019

We have examined the roles of gamma interferon (IFN-γ), nitric oxide (NO), and natural killer (NK) cells in the host resistance to infection with the blood-stage malarial parasitePlasmodium bergheiXAT, an irradiation-induced attenuated variant of the lethal strainP. bergheiNK65. Although the infection withP. bergheiXAT enhanced NK cell lytic activity of splenocytes, depletion of NK1.1+cells caused by the treatment of mice with anti-NK1.1 antibody affected neither parasitemia nor IFN-γ production by their splenocytes. TheP. bergheiXAT infection induced a large amount of NO production by splenocytes during the first peak of parasitemia, whileP. bergheiNK65 infection induced a small amount. Unexpectedly, however, mice deficient in inducible nitric oxide synthase (iNOS−/−) clearedP. bergheiXAT after two peaks of parasitemia were observed, as occurred for wild-type control mice. Although the infected iNOS−/−mouse splenocytes did not produce a detectable level of NO, they produced an amount of IFN-γ comparable to that produced by wild-type control mouse splenocytes, and treatment of these mice with neutralizing anti-IFN-γ antibody led to the progression of parasitemia and fatal outcome. CD4−/−mice infected withP. bergheiXAT could not clear the parasite, and all these mice died with apparently reduced IFN-γ production. Furthermore, treatment with carrageenan increased the susceptibility of mice toP. bergheiXAT infection. These results suggest that neither NO production nor NK cell activation is critical for the resistance toP. bergheiXAT infection and that IFN-γ plays an important role in the elimination of malarial parasites, possibly by the enhancement of phagocytic activity of macrophages.
Pseudomonas aeruginosa
Hemolytic Phospholipase C Suppresses Neutrophil Respiratory Burst Activity
Authors: Terada Lance S. , Johansen Kristine A. , Nowbar Sogol , Vasil Adriana I. , Vasil Michael L.
Published: December 2019

Pseudomonas aeruginosa
is a persistent pathogen in the airways of patients with cystic fibrosis or bronchiectasis from other causes and appears to have evolved strategies to survive the inflammatory response of the host. We hypothesized that the secreted hemolytic phospholipase C (PLC) of
P. aeruginosa
(PlcHR) would decrease neutrophil respiratory burst activity. We found that while intact wild-type
P. aeruginosa
cells stimulated moderate respiratory burst activity from human neutrophils, an isogenic mutant pseudomonas (ΔHR strain) containing a targeted deletion of the
plcHR
operon induced a much more robust oxidative burst from neutrophils. In contrast, a second pseudomonas mutant (ΔN) containing a disruption in the gene encoding the nonhemolytic PLC (PlcN) was not different from the wild type in stimulating neutrophil O
2
·−
production. Readdition of purified PlcHR to the ΔHR strain suppressed neutrophil O
2
·−
production to levels stimulated by wild-type bacteria. Interestingly, purified PlcHR decreased phorbol myristate acetate (PMA)- but not formyl methionyl-leucyl-proline (fMLP)-induced respiratory burst activity, suggesting interference by PlcHR with a protein kinase C (PKC)-specific signaling pathway. Accordingly, the PKC inhibitor bisindolylmaleimide inhibited the oxidative burst induced by either PMA or intact pseudomonas, but not by fMLP, whereas the p38 kinase inhibitor SB-203580 fully inhibited the respiratory burst induced by fMLP or the PlcHR-replete wild-type bacteria, but not PMA or the PlcHR-deficient ΔHR bacterial mutant. We conclude that expression of PlcHR by
P. aeruginosa
suppresses bacterium-induced neutrophil respiratory burst by interfering with a PKC-dependent, non-p38 kinase-dependent pathway.
Cellular Immune Responses toNeisseria meningitidisin Children
Authors: Pollard Andrew J. , Galassini Rachel , Rouppe van der Voort Eileene M. , Hibberd Martin , Booy Robert , Langford Paul , Nadel Simon , Ison Catherine , Kroll J. Simon , Poolman Jan , Levin Michael
Published: December 2019

There is an urgent need for effective vaccines against serogroup BNeisseria meningitidis. Current experimental vaccines based on the outer membrane proteins (OMPs) of this organism provide a measure of protection in older children but have been ineffective in infants. We postulated that the inability of OMP vaccines to protect infants might be due to age-dependent defects in cellular immunity. We measured proliferation and in vitro production of gamma interferon (IFN-γ), tumor necrosis factor alpha, and interleukin-10 (IL-10) in response to meningococcal antigens by peripheral blood mononuclear cells (PBMCs) from children convalescing from meningococcal disease and from controls. After meningococcal infection, the balance of cytokine production by PBMCs from the youngest children was skewed towards a TH1 response (low IL-10/IFN-γ ratio), while older children produced more TH2 cytokine (higher IL-10/IFN-γ ratio). There was a trend to higher proliferative responses by PBMCs from older children. These responses were not influenced by the presence or subtype of class 1 (PorA) OMP or by the presence of class 2/3 (PorB) or class 4 OMP. Even young infants might be expected to develop adequate cellular immune responses to serogroup BN. meningitidisvaccines if a vaccine preparation can be formulated to mimic the immune stimulus of invasive disease, which may include stimulation of TH2 cytokine production.
The Internalization Time Course of a Given Lipopolysaccharide Chemotype Does Not Correspond to Its Activation Kinetics in Monocytes
Authors: Lentschat A. , El-Samalouti V. T. , Schletter J. , Kusumoto S. , Brade L. , Rietschel E. T. , Gerdes J. , Ernst M. , Flad H.-D. , Ulmer A. J.
Published: December 2019

The prerequisites for the initiation of pathophysiological effects of endotoxin (lipopolysaccharide [LPS]) include binding to and possibly internalization by target cells. Monocytes/macrophages are prominent target cells which are activated by LPS to release various pro- and anti-inflammatory mediators. The aim of the present study was to establish a new method to determine the binding and internalization rate of different LPS chemotypes by human monocytes and to correlate these phenomena with biological activity. It was found that membrane-bound LPS disappears within hours from the surface being internalized into the cell. Further, a correlation between the kinetics of internalization and the length of the sugar chain as well as an inverse correlation between the time course of internalization and LPS hydrophobicity was revealed. Comparison of the internalization kinetics of different LPS chemotypes with kinetics of tumor necrosis factor alpha release and kinetics of oxidative burst did not reveal any correlation of these parameters. These findings suggest that cellular internalization of and activation by LPS are mechanisms which are independently regulated.
Human Opsonins Induced during Meningococcal Disease Recognize Outer Membrane Proteins PorA and PorB
Authors: Lehmann A. K. , Halstensen A. , Aaberge I. S. , Holst J. , Michaelsen T. E. , Sørnes S. , Wetzler L. M. , Guttormsen H.-K.
Published: December 2019

Human opsonins directed against specific meningococcal outer membrane structures in sera obtained during meningococcal disease were quantified with a recently developed antigen-specific, opsonin-dependent phagocytosis and oxidative burst assay. Outer membrane vesicles (OMVs) and PorA (class 1) and PorB (class 3) proteins purified from mutants of the same strain (44/76; B:15:P1.7.16) were adsorbed to fluorescent beads, opsonized with acute- and convalescent-phase sera from 40 patients with meningococcal disease, and exposed to human leukocytes. Flow cytometric quantitation of the resulting leukocyte phagocytosis products (PPs) demonstrated that disease-induced serum opsonins recognized meningococcal OMV components and both porins. The PP
PorA
and PP
PorB
values induced by convalescent-phase sera correlated positively with the PP
OMV
values. However, the PP
PorB
values were higher than the PP
PorA
values in convalescent-phase sera (medians [ranges] of 754 [17 to 1,057] and 107 [4 to 458], respectively) (
P
< 0.0001) and correlated positively with higher levels of immunoglobulin G against PorB than against PorA as evaluated by enzyme-linked immunosorbent assay. Extensive individual variations in the anti-OMV and antiporin serum opsonic activities between patients infected by serotypes and serosubtypes homologous and heterologous to the target antigens were observed. Simultaneously measured oxidative burst activity correlated with the opsonophagocytosis, an indication that both of these important steps in the in vitro phagocytic elimination of meningococci are initiated by opsonins directed against OMV components, including PorA and PorB. In conclusion, human patient opsonins against meningococcal OMV components and in particular PorB epitopes were identified by this new method, which might facilitate selection of opsonin-inducing meningococcal antigens for inclusion in future vaccines.
The Human Cationic Antimicrobial Protein (hCAP18), a Peptide Antibiotic, Is Widely Expressed in Human Squamous Epithelia and Colocalizes with Interleukin-6
Authors: Frohm Nilsson Margareta , Sandstedt Bengt , Sørensen Ole , Weber Günther , Borregaard Niels , Ståhle-Bäckdahl Mona
Published: December 2019

Peptide antibiotics are widespread in nature and, by providing a rapid first line of defense, may be key players in the innate immune system. Although epithelia are the main barriers shielding the internal environment from microorganisms, the role for peptide antibiotics in epithelial protection is unclear. We recently reported that the human cationic antimicrobial protein hCAP18, the precursor of the antimicrobial peptide called LL-37, is not expressed by normal human keratinocytes but is induced in various inflammatory skin disorders. In the present study we demonstrate that hCAP18 is consistently expressed at both mRNA and protein levels in squamous epithelia of the mouth, tongue, esophagus, cervix, and vagina in humans. The gene for hCAP18 contains promoter elements that are potentially regulated by interleukin-6, and our data further show a colocalization between interleukin-6 and hCAP18 expression in these tissues. Our finding that hCAP18 is widely produced in squamous epithelia suggests a role for this peptide in epithelial antimicrobial defense. Furthermore, colocalization with interleukin-6 indicates a potential local mechanism for the upregulation of hCAP18 at the epithelial surfaces.
Vaccination of Guinea Pigs with Nutritionally Impaired Avirulent Mutants of
Mycobacterium bovis
Protects against Tuberculosis
Authors: de Lisle Geoffrey W. , Wilson Theresa , Collins Desmond M. , Buddle Bryce M.
Published: December 2019

Four nutritionally impaired strains of
Mycobacterium bovis
produced by illegitimate recombination were tested for their ability to protect guinea pigs against intratracheal challenge with virulent
M. bovis
. All four strains and
M. bovis
BCG induced significant levels of protection as measured by the reduced spread of infection to the spleen and liver. In animals vaccinated with BCG or two of the other strains, the bacterial counts from the lungs were significantly lower than those of the nonvaccinated animals.
Specific Antibodies Reactive with the 22-Kilodalton Major Outer Surface Protein of
Borrelia anserina
Ni-NL Protect Chicks from Infection
Authors: Sambri Vittorio , Marangoni Antonella , Olmo Andrea , Storni Elisa , Montagnani Marco , Fabbi Massimo , Cevenini Roberto
Published: December 2019

An outer surface lipoprotein of 22 kDa was identified in the avian pathogen
Borrelia anserina
Ni-NL by using antibody preparations reactive with bacterial surface-exposed proteins. Amino acid sequence analysis of the 22-kDa protein demonstrated 90% identity with VmpA of
B. turicatae
, suggesting that the protein belongs to the family of 20-kDa outer surface proteins of the genus
Borrelia
. All of the 60 chicks intramuscularly treated with antibodies specifically reacting with the 22-kDa protein and infected with strain Ni-NL were completely protected from infection, since no spirochetemia was detected, and from death. Control chicks were treated with immune sera raised against apathogenic strain
B. anserina
Es, which expresses a prominent 20-kDa polypeptide that is also a member of the Vmp family but does not cross-react immunologically with the 22-kDa protein of the Ni-NL strain. These animals, infected with
B. anserina
Ni-NL, showed a high degree of spirochetemia 10 days after infection, and all died between 14 and 21 days after infection. The results showed that the 22-kDa surface protein of
B. anserina
Ni-NL is a determinant of the pathogenic potential of the strain and also confirmed that only strain-specific antibodies are protective against
B. anserina
infection.
Single-Dose Mucosal Immunization with Biodegradable Microparticles Containing aSchistosoma mansoniAntigen
Authors: Baras Benoît , Benoit Marie-Ange , Dupré Loïc , Poulain-Godefroy Odile , Schacht Anne-Marie , Capron André , Gillard Jean , Riveau Gilles
Published: December 2019

The purpose of this work was to assess the immunogenicity of a single nasal or oral administration of recombinant 28-kDa glutathioneS-transferase ofSchistosoma mansoni(rSm28GST) entrapped by poly(lactide-co-glycolide) (PLG)- or polycaprolactone (PCL)-biodegradable microparticles. Whatever the polymer and the route of administration used, the equivalent of 100 μg of entrapped rSm28GST induced a long-lasting and stable antigen-specific serum antibody response, with a peak at 9 to 10 weeks following immunization. Isotype profiles were comparable, with immunoglobulin G1 being the predominant isotype produced. The abilities of specific antisera to neutralize the rSm28GST enzymatic activity have been used as criteria of immune response quality. Pooled 10-week sera from mice receiving PLG microparticles by the nasal or oral route neutralized the rSm28GST enzymatic activity, whereas sera of mice receiving either PCL microparticles, free rSm28GST, or empty microparticles inefficiently neutralized this enzymatic activity. Finally, this study shows that a single administration of these microparticles could provide distinct and timely release pulses of microencapsulated antigen, which might greatly facilitate future vaccine development.
Mechanisms of Internalization ofStaphylococcus aureusby Cultured Human Osteoblasts
Authors: Jevon Marc , Guo Chuanbin , Ma Beechai , Mordan Nicky , Nair Sean P. , Harris Malcolm , Henderson Brian , Bentley George , Meghji Sajeda
Published: December 2019

Staphylococcus aureusis an important bone pathogen, and evidence shows that this organism is internalized by chick osteoblasts. Here we report thatS. aureusis internalized by human osteoblasts. Internalization was inhibited by monodansylcadaverine and cytochalasin D and to a lesser extent by ouabain, monensin, colchicine, and nocodazole. We propose that internalization occurs via a receptor-mediated pathway, requiring the participation of cytoskeletal elements, principally actin.
Identification and Characterization of a Novel Fibronectin-Binding Protein on the Surface of Group A Streptococci
Authors: Rocha Claudia L. , Fischetti Vincent A.
Published: December 2019

Understanding the role surface proteins play in the interaction of group A streptococci with epithelial cells is an important step toward the development of new strategies to fight infections. Fibronectin-binding proteins in streptococci and staphylococci have been described as important mediators for adherence to eukaryotic cells. In the present study we describe a new
Streptococcus pyogenes
fibronectin-binding protein (PFBP). The gene encoding the PFBP protein (
pfbp
) was identified from an M12 strain genomic library. It encodes a protein of 127.4 kDa which contains the LPXTGX motif characteristic of cell wall-associated proteins in gram-positive organisms and is among the largest surface molecules described for group A streptococci. The
pfbp
gene is transcribed during cell growth and was present in several class I and II streptococcal strains tested. The deduced amino acid sequence of PFBP exhibits a variable N-terminal region and a conserved C-terminal region when compared to most fibronectin-binding proteins identified from other gram-positive bacteria. The N-terminal region presents a stretch of 105 amino acids with no homology with N-terminal regions of previously described fibronectin-binding molecules, while the C-terminal region contains three repeat domains that share significant similarity with the repeat regions of fibronectin-binding proteins from
S. pyogenes
,
S. dysgalactiae
, and
S. equisimilis
. The PFBP repeated region, when expressed on the surface of
S. gordonii
, a commensal organism, binds to soluble and immobilized fibronectin. This study also shows that, in addition to
pfbp
, a second gene homologous with that of protein F1 (which also codes for a fibronectin-binding protein) is transcribed during cell growth in the same
S. pyogenes
strain.
Infection-Associated Decline of Cape Buffalo Blood Catalase Augments Serum Trypanocidal Activity
Authors: Wang Qin , Murphy Noel , Black Samuel J.
Published: December 2019

Clearance of trypanosomes from the blood of infected Cape buffalo was associated with the development of two responses: (i) complement-dependent and clone-specific lytic activity and (ii) complement-independent trypanocidal activity that was not restricted by trypanosome clone or species. This latter activity was mediated by H
2
O
2
and required the presence of xanthine oxidase in serum but not the addition of purine substrates. Expression of the xanthine oxidase-dependent trypanocidal activity in Cape buffalo serum was coincident with, and required, a decline in its H
2
O
2
catabolic activity. The H
2
O
2
catabolic activity of Cape buffalo serum was due solely to catalase and declined by eightfold around the time that trypanosomes were cleared from the blood, accompanied by a fivefold drop in erythrocyte-associated catalase activity. The Cape buffalo did not develop subsequent parasitemic waves. Clearance of parasitemia in similarly infected cattle was also associated with development of trypanosome clone-specific lytic activity, but not with the acquisition of H
2
O
2
-dependent trypanocidal activity in serum, and the cattle supported recurring parasitemia. The lack of trypanocidal activity in pre- and postinfection cattle sera was due to their low content of xanthine oxidase and sustained catalase activity. These data strongly suggest that an infection-induced serum oxidative response, the efficacy of which is amplified by a decline in blood catalase, contributes to suppression of recurring parasitemia in Cape buffalo.
CD4
+
T Cells and the Proinflammatory Cytokines Gamma Interferon and Interleukin-6 Contribute to Alveolar Bone Loss in Mice
Authors: Baker Pamela J. , Dixon Mark , Evans R. Todd , Dufour Lisa , Johnson Ellis , Roopenian Derry C.
Published: December 2019

In this study, we used a mouse model to examine the role of the adaptive immune response in alveolar bone loss induced by oral infection with the human gram-negative anaerobic bacterium
Porphyromonas gingivalis
. Severe combined immunodeficient mice, which lack B and T lymphocytes, exhibited considerably less bone loss than did immunocompetent mice after oral infection, suggesting that lymphocytes contribute to this process. Bone loss after oral infection was decreased in mice deficient in major histocompatibility complex (MHC) class II-responsive CD4
+
T cells, but no change in bone loss was observed in mice deficient in MHC class I-responsive CD8
+
T cells or NK1
+
T cells. Mice lacking the cytokine gamma interferon or interleukin-6 also demonstrated decreased bone loss. These results suggest that the adaptive immune response, and in particular CD4
+
T cells and the proinflammatory cytokines that they secrete, are important effectors of bone loss consequent to
P. gingivalis
oral infection. The studies also reinforce the utility of the mouse oral infection model in dissecting the pathobiology of periodontal disease.
Antigenic and Molecular Conservation of the Gonococcal NspA Protein
Authors: Plante Martin , Cadieux Nathalie , Rioux Clément R. , Hamel Josée , Brodeur Bernard R. , Martin Denis
Published: December 2019

A low-molecular-weight protein named NspA (neisserial surface protein A) was recently identified in the outer membrane of all
Neisseria meningitidis
strains tested. Antibodies directed against this protein were shown to protect mice against an experimental meningococcal infection. Hybridization experiments clearly demonstrated that the
nspA
gene was also present in the genomes of the 15
Neisseria gonorrhoeae
strains tested. Cloning and sequencing of the
nspA
gene of
N. gonorrhoeae
B2 revealed an open reading frame of 525 nucleotides coding for a polypeptide of 174 amino acid residues, with a calculated molecular weight of 18,316 and a pI of 10.21. Comparison of the predicted amino acid sequence of the NspA polypeptides from the gonococcal strains B2 and FA1090, together with that of the meningococcal strain 608B, revealed an identity of 93%, suggesting that the NspA protein is highly conserved among pathogenic
Neisseria
strains. The level of identity rose to 98% when only the two gonococcal predicted NspA polypeptides were compared. To evaluate the level of antigenic conservation of the gonococcal NspA protein, monoclonal antibodies (MAbs) were generated. Four of the seven NspA-specific MAbs described in this report recognized their corresponding epitope in 100% of the 51
N. gonorrhoeae
strains tested. Radioimmunobinding assays clearly indicated that the gonococcal NspA protein is exposed at the surface of intact cells.
Differential Induction of Colitis and Gastritis in HLA-B27 Transgenic Rats Selectively Colonized withBacteroides vulgatusorEscherichia coli
Authors: Rath Heiko C. , Wilson Kenneth H. , Sartor R. Balfour
Published: December 2019

Resident bacteria play an important role in initiating and perpetuating gastrointestinal inflammation. We previously demonstrated that six commensal bacteria includingBacteroides vulgatuscaused more aggressive colitis and gastritis in HLA-B27 transgenic rats than did the other five bacteria withoutB. vulgatus. This study compared the degree of gastrointestinal inflammation in gnotobiotic HLA-B27 transgenic rats monoassociated with eitherB. vulgatusorEscherichia coli. Gnotobiotic transgenic rats raised in Trexler isolators were selectively colonized with eitherB. vulgatusorE. coli. Control rats were either germfree or colonized with six common commensal bacteria (Streptococcus faecium,E. coli,Streptococcus avium,Eubacterium contortum,Peptostreptococcus productus, andB. vulgatus[DESEP-B]). After 1 month, all the rats were killed and tissues were prepared for histologic and biochemical evaluation. Colitis induced byB. vulgatusmonoassociation was almost equal to that in DESEP-B-colonized rats and was significantly more severe thanE. coli-induced colitis, which was absent by histological testing and mild by colonic myeloperoxidase and interleukin-1β concentration determinations. However, gastritis was detectable only in DESEP-B-associated rats. These studies suggest that not all resident bacteria have equal proinflammatory capabilities, sinceB. vulgatusalone is more active thanE. colialone in inducing colitis, and that colitis and gastritis result from different luminal bacterial stimuli.
Anthrax Toxin Entry into Polarized Epithelial Cells
Authors: Beauregard Kathryn E. , Wimer-Mackin Susan , Collier R. John , Lencer Wayne I.
Published: December 2019

We examined the entry of anthrax edema toxin (EdTx) into polarized human T84 epithelial cells using cyclic AMP-regulated Cl
−
secretion as an index of toxin entry. EdTx is a binary A/B toxin which self assembles at the cell surface from anthrax edema factor and protective antigen (PA). PA binds to cell surface receptors and delivers EF, an adenylate cyclase, to the cytosol. EdTx elicited a strong Cl
−
secretory response when it was applied to the basolateral surface of T84 cells but no response when it was applied to the apical surface. PA alone had no effect when it was applied to either surface. T84 cells exposed basolaterally bound at least 30-fold-more PA than did T84 cells exposed apically, indicating that the PA receptor is largely or completely restricted to the basolateral membrane of these cells. The PA receptor did not fractionate with detergent-insoluble caveola-like membranes as cholera toxin receptors do. These findings have implications regarding the nature of the PA receptor and confirm the view that EdTx and CT coopt fundamentally different subcellular systems to enter the cell and cause disease.
Interleukin-12 Enhances Antifungal Activity of Human Mononuclear Phagocytes againstAspergillus fumigatus: Implications for a Gamma Interferon-Independent Pathway
Authors: Roilides Emmanuel , Tsaparidou Sevasti , Kadiltsoglou Isaac , Sein Tin , Walsh Thomas J.
Published: December 2019

The potential of recombinant human interleukin-12 (IL-12) to enhance the capacity of human monocytes (MNC) to elicit an oxidative burst and damage hyphae ofAspergillus fumigatuswas investigated. Incubation of peripheral blood mononuclear cells (PBMC) from healthy adults with 10 to 100 ng of IL-12/ml at 37°C for 2 to 3 days enhanced the production of superoxide anion (O2−) in response to phorbol myristate acetate (PMA) (P= 0.04) and unopsonizedA. fumigatushyphae (P= 0.03) and further enhanced hyphal damage (P= 0.009). Anti-gamma interferon (anti-IFN-γ) blocked secretion of IFN-γ by IL-12-treated PBMC but did not inhibit IL-12-induced O2−production by these cells in response to PMA. In addition, IL-12-treated elutriated MNC secreted no IFN-γ or tumor necrosis factor alpha but exhibited enhanced O2−production compared to controls (P= 0.013). These findings demonstrate that IL-12 augments oxidative antifungal activities of MNC via an IFN-γ-independent route, suggesting a novel pathway of IL-12 action in antifungal defense.
Levels of Gamma Interferon and Interleukin-4 Are Inversely Related to the Levels of Their Corresponding Autoantibodies in Patients with Lower Respiratory Tract Infection
Authors: ElKarim Rihab , Granert Carl , Lindquist Lars , Link Hans , Bakhiet Moiz
Published: December 2019

To study the involvement of cytokines and their corresponding autoantibodies (Aabs) in inflammatory mechanisms in patients with lower respiratory tract infections, blood samples were taken from patients at the time of admission to the hospital and before treatment. Cell-released capturing enzyme-linked immunosorbent assay was used to measure the levels of gamma interferon (IFN-γ) and interleukin-4 (IL-4) produced spontaneously by peripheral mononuclear cells (PMNC). ELISA was used to measure Aabs to these cytokines in sera. The levels of both cytokines were inversely related to the levels of their corresponding Aabs. While a high level of IFN-γ was observed together with a low level of anti-IFN-γ Aab, decreased IL-4 levels were observed with increased levels of Aabs to IL-4. Immunoglobulins were purified, digested to obtain Fab fragments, and tested for specificity and cross-reactivity. The Aabs and their Fab fragments were tested in cytokine biological assays and showed neutralizing effects. Our data demonstrated increased levels of the proinflammatory cytokine IFN-γ and decreased release of the anti-inflammatory cytokine IL-4 during early presentation of lower respiratory tract infection. The levels of these cytokines were inversely related to the levels of their corresponding Aabs that exhibited regulatory effects on the cytokine biological function in vitro.
Host Defense againstMycobacterium aviumDoes Not Have an Absolute Requirement for Major Histocompatibility Complex Class I-Restricted T Cells
Authors: Bermudez Luiz E. , Petrofsky Mary
Published: December 2019

The role of CD8+T cells was evaluated in a mouse model of disseminatedMycobacterium aviuminfection. C57BL/6J and C57BL/6Jβ2−/−(β2−/−) mice were infected intravenously, and the number of viable bacteria in each liver and spleen was determined. No significant difference between the number of bacteria in the two strains of mice was observed at 2, 4, 6, and 8 weeks after infection. Histopathological examination of granulomas from C57BL/6J and β2−/−mice did not show any difference either in the number of organisms per granuloma or in the size of the granulomas. Investigation of the cytokine profile in the spleen demonstrated that the β2−/−strain of mice produced a significantly lower amount of gamma interferon at 8 weeks after infection and significantly increased concentrations of tumor necrosis factor alpha compared with that from the wild-type mouse. Interleukin-12 and transforming growth factor β1levels did not differ between the two strains of mice at 2, 4, 6, and 8 weeks. Although previous work had found that host response againstMycobacterium tuberculosisinvolves major histocompatibility complex class I-restricted T cells, our results indicate that chronic deficiency of CD8+T cells does not lead to a different expression of the disease and that if CD8+T cells are involved in the host response, their function can be assumed by other immune cells.
A Conventional Beagle Dog Model for Acute and Chronic Infection withHelicobacter pylori
Authors: Rossi Giacomo , Rossi Michela , Vitali Claudia G. , Fortuna Damiano , Burroni Daniela , Pancotto Laura , Capecchi Sonia , Sozzi Sabrina , Renzoni Giacomo , Braca Giovanni , Del Giudice Giuseppe , Rappuoli Rino , Ghiara Paolo , Taccini Ennio
Published: December 2019

Helicobacter pylorihas been widely recognized as an important human pathogen responsible for chronic gastritis, peptic ulcers, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma. Little is known about the natural history of this infection since patients are usually recognized as having the infection only after years or decades of chronic disease. Several animal models ofH. pyloriinfection, including those with different species of rodents, nonhuman primates, and germ-free animals, have been developed. Here we describe a new animal model in which the clinical, pathological, microbiological, and immunological aspects of human acute and chronic infection are mimicked and which allows us to monitor these aspects of infection within the same individuals. Conventional Beagle dogs were infected orally with a mouse-adapted strain ofH. pyloriand monitored for up to 24 weeks. Acute infection caused vomiting and diarrhea. The acute phase was followed by polymorphonuclear cell infiltration, interleukin 8 induction, mononuclear cell recruitment, and the appearance of a specific antibody response againstH. pylori. The chronic phase was characterized by gastritis, epithelial alterations, superficial erosions, and the appearance of the typical macroscopic follicles that in humans are considered possible precursors of MALT lymphoma. In conclusion, infection in this model mimics closely human infection and allows us to study those phases that cannot be studied in humans. This new model can be a unique tool for learning more about the disease and for developing strategies for treatment and prevention.
Increase in Gamma Interferon-Secreting CD8+, as Well as CD4+, T Cells in Lungs following Aerosol Infection withMycobacterium tuberculosis
Authors: Feng Carl G. , Bean Andrew G. D. , Hooi Helena , Briscoe Helen , Britton Warwick J.
Published: December 2019

Although it is well established that CD4+T cells are required for the protective immune response against tuberculosis (TB), there is some evidence that CD8+T cells are also involved in the host response toMycobacterium tuberculosis. There is, however, a paucity of information on the pulmonary CD8+T-cell response during infection. We therefore have compared the changes in both CD8+and CD4+T cells following aerosol infection withM. tuberculosis. There was an observed delay between the peak of infection and the activated T-cell response in the lung. The kinetics of CD8+and CD4+T-cell responses in the lung were identical, both peaking at week 8, 4 weeks later than the peak of cellular response in draining lymph nodes. Similar changes in activation/memory phenotypes occurred on the pulmonary CD8+and CD4+T cells. Following in vitro restimulation, both subsets synthesized gamma interferon, a cytokine essential for controllingM. tuberculosisinfection. Since lung CD8+T cells are actively expanded during aerosolM. tuberculosisinfection, it is important that both CD8+and CD4+T cells be targeted in the design of future TB vaccines.
Carrageenan Primes Leukocytes To Enhance Lipopolysaccharide-Induced Tumor Necrosis Factor Alpha Production
Authors: Ogata Masanori , Matsui Takashi , Kita Toshiro , Shigematsu Akio
Published: December 2019

We have previously reported that pretreatment with carrageenan (CAR) enhances lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α) production in and lethality for mice. Whole blood cultured in vitro was used to show that CAR pretreatment results in about a 200-fold increase in LPS-induced TNF-α production. CAR by itself did not induce TNF-α production. However, CAR-treated cultured medium sensitized whole blood to make more LPS-induced TNF than did saline-treated cultured medium in vitro. It was also demonstrated that CAR pretreatment increases TNF-α mRNA levels of both blood cells and peritoneal exudate cells, but not of bone marrow cells. Immunoelectron microscopic analysis revealed that polymorphonuclear leukocytes and macrophages are TNF-α-producing cells in CAR-treated mice. In CAR-treated mice, TNF-α was seen early after LPS injection in leukocytes in hepatic sinusoids and on the surfaces of endothelial cells. TNF-α was also detected late after LPS injection in hepatocytes which become edematous. These results suggest that CAR primes leukocytes to produce TNF-α in response to LPS and that they play an important role in the pathogenesis of liver injury.
Differences in the Carboxy-Terminal (Putative Phospholipid Binding) Domains of
Clostridium perfringens
and
Clostridium bifermentans
Phospholipases C Influence the Hemolytic and Lethal Properties of These Enzymes
Authors: Jepson Marie , Howells Angela , Bullifent Helen L. , Bolgiano Barbara , Crane Dennis , Miller Julie , Holley Jane , Jayasekera Pramukh , Titball Richard W.
Published: December 2019

The phospholipases C of
C. perfringens
(alpha-toxin) and
C. bifermentans
(Cbp) show >50% amino acid homology but differ in their hemolytic and toxic properties. We report here the purification and characterisation of alpha-toxin and Cbp. The phospholipase C activity of alpha-toxin and Cbp was similar when tested with phosphatidylcholine in egg yolk or in liposomes. However, the hemolytic activity of alpha-toxin was more than 100-fold that of Cbp. To investigate whether differences in the carboxy-terminal domains of these proteins were responsible for differences in the hemolytic and toxic properties, a hybrid protein (N
bi
C
α
) was constructed comprising the N domain of Cbp and the C domain of alpha-toxin. The hemolytic activity of N
bi
C
α
was 10-fold that of Cbp, and the hybrid enzyme was toxic. These results confirm that the C-terminal domain of these proteins confers different properties on the enzymatically active N-terminal domain of these proteins.
Development of Antibody Isotype Responses toSchistosoma mansoniin an Immunologically Naive Immigrant Population: Influence of Infection Duration, Infection Intensity, and Host Age
Authors: Naus Cynthia W. A. , Kimani Gachuhi , Ouma John H. , Fulford Anthony J. C. , Webster Michelle , van Dam Govert J. , Deelder André M. , Butterworth Anthony E. , Dunne David W.
Published: December 2019

We have identified the influence of host and parasite factors that give rise to characteristic antibody isotype profiles with age seen in human populations living in different areas of schistosomiasis endemicity. This is important in the immunobiology of this disease. It is also of interest in the context of human responses to chronic antigen stimulation, vaccines, allergens, and other pathogens. In populations exposed to endemic schistosomiasis, factors such as intensity and duration of infection are age dependent. They therefore confound the influence of host age on antiparasite responses. Here, we resolved these confounding factors by comparing the developing antibody responses of an immunologically naive immigrant population as they acquired the infection for the first time with those of chronically infected resident inhabitants of the same region ofSchistosoma mansoniendemicity in Kenya. Recent arrival in the area strongly favored immunoglobulin G3 (IgG3) responses against the parasite. The antibody isotype responses associated with human susceptibility to reinfection after chemotherapy were elevated in those suffering high intensities of infection (IgG4 responses against worm and egg antigens) or were characteristic responses of young children irrespective of the intensity or duration of infection (IgG2 responses against egg antigen). IgE responses against the adult worm, a response associated with resistance to reinfection after chemotherapy, increased with the ages of infected individuals and were also favored in those currently suffering higher intensities of infection.
Wheat Germ Agglutinin Induces NADPH-Oxidase Activity in Human Neutrophils by Interaction with Mobilizable Receptors
Authors: Karlsson Anna
Published: December 2019

Wheat germ agglutinin (WGA), a lectin with specificity forN-acetylglucosamine and sialic acid, was investigated with respect to its ability to activate the NADPH-oxidase of in vivo-exudated neutrophils (obtained from a skin chamber), and the activity was compared to that of peripheral blood neutrophils. The exudate cells responded to WGA, by both releasing reactive oxygen species into the extracellular milieu and producing oxygen metabolites intracellularly. The peripheral blood cells were unresponsive. To mimic the in vivo-exuded neutrophils with regards to receptor exposure, peripheral blood neutrophils were induced to mobilize their granules and vesicles to varying degrees (in vitro priming), prior to challenge with WGA. The oxidative response to WGA increased with increasing levels of granule mobilization, and the receptor(s) could be shown to reside in the secretory vesicles and/or the gelatinase granules in resting neutrophils. Several WGA-binding glycoproteins were detected in subcellular fractions containing these organelles. The extra- and intracellular NADPH-oxidase responses showed differences in sialic acid dependency, indicating that these two responses are mediated by different receptor structures.
Effect of Peroxisome Proliferator-Activated Receptor Alpha Activators on Tumor Necrosis Factor Expression in Mice during Endotoxemia
Authors: Hill Molly R. , Clarke Stephen , Rodgers Kerry , Thornhill Brandi , Peters Jeffrey M. , Gonzalez Frank J. , Gimble Jeffrey M.
Published: December 2019

Inflammatory mediators orchestrate the host immune and metabolic response to acute bacterial infections and mediate the events leading to septic shock. Tumor necrosis factor (TNF) has long been identified as one of the proximal mediators of endotoxin action. Recent studies have implicated peroxisome proliferator-activated receptor alpha (PPARα) as a potential target to modulate regulation of the immune response. Since PPARα activators, which are hypolipidemic drugs, are being prescribed for a significant population of older patients, it is important to determine the impact of these drugs on the host response to acute inflammation. Therefore, we examined the role of PPARα activators on the regulation of TNF expression in a mouse model of endotoxemia. CD-1 mice treated with dietary fenofibrate or Wy-14,643 had fivefold-higher lipopolysaccharide (LPS)-induced TNF plasma levels than LPS-treated control-fed animals. Higher LPS-induced TNF levels in drug-fed animals were reflected physiologically in significantly lower glucose levels in plasma and a significantly lower 50% lethal dose than those in LPS-treated control-fed animals. Utilizing PPARα wild-type (WT) and knockout (KO) mice, we showed that the effect of fenofibrate on LPS-induced TNF expression was indeed mediated by PPARα. PPARα WT mice fed fenofibrate also had a fivefold increase in LPS-induced TNF levels in plasma compared to control-fed animals. However, LPS-induced TNF levels were significantly decreased and glucose levels in plasma were significantly increased in PPARα KO mice fed fenofibrate compared to those in control-fed animals. Data from peritoneal macrophage studies indicate that Wy-14,643 modestly decreased TNF expression in vitro. Similarly, overexpression of PPARα in 293T cells decreased activity of a human TNF promoter-luciferase construct. The results from these studies suggest that any anti-inflammatory activity of PPARα in vivo can be masked by other systemic effects of PPARα activators.