bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enteric β-Defensin: Molecular Cloning and Characterization of a Gene with Inducible Intestinal Epithelial Cell Expression Associated with
Cryptosporidium parvum
Infection
Authors: Tarver Alan P. , Clark Douglas P. , Diamond Gill , Russell John P. , Erdjument-Bromage Hediye , Tempst Paul , Cohen Kenneth S. , Jones Douglas E. , Sweeney Ray W. , Wines Mary , Hwang Shirley , Bevins Charles L. 
Published: December 2019

ABSTRACT

A growing body of evidence suggests that endogenous antibiotics contribute to the innate defense of mammalian mucosal surfaces. In the cow, β-defensins constitute a large family of antibiotic peptides whose members have been previously isolated from the respiratory and oral mucosa, as well as circulating phagocytic cells. A novel bovine genomic clone with sequence related to those of these α-defensins was isolated and characterized. The corresponding cDNA was isolated from a small intestinal library; its open reading frame predicts a deduced sequence of a novel β-defensin, which we designate enteric β-defensin (EBD). Northern blot analysis of a variety of bovine tissues revealed that EBD mRNA is highly expressed in the distal small intestine and colon, anatomic locations distinct from those for previously characterized β-defensins. EBD mRNA was further localized by in situ hybridization to epithelial cells of the colon and small intestinal crypts. Infection of two calves with the intestinal parasite
Cryptosporidium parvum
induced 5- and 10-fold increases above control levels of EBD mRNA in intestinal tissues. An anchored-PCR strategy was used to identify other β-defensin mRNAs expressed in the intestine. In addition to that of EBD, several low-abundance cDNAs which corresponded to other β-defensin mRNAs were cloned. Most of these clones encoded previously characterized β-defensins or closely related isoforms, but two encoded a previously uncharacterized prepro-β-defensin. Northern blot evidence supported that all of these other β-defensin genes are expressed at levels lower than that of the EBD gene in enteric tissue. Furthermore, some of these β-defensin mRNAs were abundant in bone marrow, suggesting that in enteric tissue their expression may be in cells of hematopoietic origin. Extracts of small intestinal mucosa obtained from healthy cows have numerous active chromatographic fractions as determined by an antibacterial assay, and one peptide was partially purified. The peptide corresponded to one of the low-abundance cDNAs. This study provides evidence of β-defensin expression in enteric tissue and that the mRNA encoding a major β-defensin of enteric tissue, EBD, is inducibly expressed in enteric epithelial cells. These findings support the proposal that β-defensins may contribute to host defense of enteric mucosa.
Purification and Expression of the Tf190 Adhesin inTritrichomonas foetus
Authors: Shaia Carl I. , Voyich Jovanka , Gillis Shaun J. , Singh B. N. , Burgess Donald E. 
Published: December 2019

ABSTRACTBovine trichomoniasis is a sexually transmitted disease caused byTritrichomonas foetusand characterized by early embryo loss. The mechanism of this loss is not known, although the parasite is known to cause inflammation and to have the ability to kill host cells by a contact-dependent cytotoxic mechanism. Antibody specific for a 190,000-Da surface complex (Tf190) was previously shown to inhibit this adhesion. In this study we used immunoaffinity chromatography to purify Tf190 fromT. foetusin order to analyze its composition and examine its expression. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified Tf190 followed by silver staining revealed three components of Tf190. Western blotting and antibody-binding experiments showed that the 140- and 60-kDa bands were immunogenic. By using a battery of monoclonal antibodies (MAbs) periodate-sensitive epitopes were identified on Tf190, suggesting that these epitopes contained carbohydrate structures. Analyses of affinity-purified Tf190 by high-performance liquid chromatography and gas-liquid chromatography demonstrated the presence of the monosaccharides and lipids known to be prominent constituents of the lipophosphoglycan (LPG) ofT. foetus. Flow cytometry experiments on several isolates ofT. foetuswith Tf190-specific antibodies revealed that Tf190 was present on subpopulations of all isolates but that not all epitopes were present on every isolate. This pattern of reactivities on the different parasite isolates was confirmed by Western blots of whole-parasite extracts probed with MAbs and antiserum. These results suggest that although variation in the expression of epitopes of Tf190 occurs in different strains ofT. foetus, the Tf190 adhesion complex is widespread in different populations of the parasite. The data further suggest that immunogenic structures, important in the adhesion ofT. foetusto mammalian cells, are located in the LPG-like component of Tf190.
Endotoxin Binding and Elimination by Monocytes: Secretion of Soluble CD14 Represents an Inducible Mechanism Counteracting Reduced Expression of Membrane CD14 in Patients with Sepsis and in a Patient with Paroxysmal Nocturnal Hemoglobinuria
Authors: Hiki Naoki , Berger Dieter , Prigl Claus , Boelke Edwin , Wiedeck Heidemarie , Seidelmann Manuela , Staib Ludger , Kaminishi Michio , Oohara Takeshi , Beger Hans G. 
Published: December 2019

ABSTRACTLittle is known about the role of peripheral blood mononuclear cells (PBMCs) in lipopolysaccharide (LPS) elimination. We studied the endotoxin elimination capacities (EEC) of PBMCs of 15 healthy volunteers, 13 patients with sepsis, and 1 patient suffering from paroxysmal nocturnal hemoglobinuria (PNH). Although expression of CD14, the best-characterized receptor for LPS to date, was reduced from 93.6% ± 0.8% in healthy subjects to 50.5% ± 6.5% in patients with sepsis and was 0.3% in a patient with septic PNH, EEC were found to be unchanged. There was no difference in the amount of tumor necrosis factor alpha (TNF-α) released by PBMCs of healthy donors and patients with sepsis. Anti-CD14 antibodies (MEM-18) completely suppressed EEC, binding of fluorescein isothiocyanate-labeled LPS to monocytes as determined by FACScan analysis, and TNF-α release in all three groups studied. The concentrations of soluble CD14 (sCD14) secreted by endotoxin-stimulated PBMCs from healthy donors and patients with sepsis amounted to 4.5 ± 0.4 and 20.1 ± 1.8 ng/ml, respectively. Based on our results, we suggest that PBMCs eliminate LPS by at least two different mechanisms; in healthy subjects, the membrane CD14 (mCD14) receptor is the most important factor for LPS elimination, while in patients with sepsis (including the septic state of PNH), increased sCD14 participates in LPS elimination. Secretion of sCD14 is strongly enhanced under conditions of low expression of mCD14 in order to counteract the reduction of mCD14 and maintain the function of monocytes. This sCD14 may substitute the role of mCD14 in LPS elimination during sepsis. The elimination of LPS by PBMCs correlates with the binding reaction and the secretion of TNF-α.
Relationship of Impairment of Schistosome 28-Kilodalton GlutathioneS-Transferase (GST) Activity to Expression of Immunity toSchistosoma mattheeiin Calves Vaccinated with RecombinantSchistosoma bovis28-Kilodalton GST
Authors: Grzych Jean-Marie , De Bont Jan , Liu Jinli , Neyrinck Jean-Loup , Fontaine Josette , Vercruysse Jozef , Capron André 
Published: December 2019

ABSTRACTSera from calves vaccinated with the recombinantSchistosoma bovis-derived 28-kDa glutathioneS-transferase (28GST) and subsequently naturally or experimentally exposed toSchistosoma mattheeiwere studied for their content of specific immunoglobulin G (IgG) and IgA antibodies to recombinantS. bovis28GST as well as for their capacity to inhibit the enzymatic activity of the antigen. The results were analyzed in regard to the presence (natural infection) or absence (experimental infection) of a protective effect(s) (reductions in worm burden, egg load, fecal egg counts, and excretion of viable eggs) towardS. mattheeichallenge. Under such conditions, no differences in the IgG- and IgA-specific antibodies to recombinantS. bovis28GST or in the ability to block the catalytic function of the antigen between the two groups were recorded. Nevertheless, correlation analysis between the specific antibody responses to recombinantS. bovis28GST and the inhibition of GST activity suggested an association with IgG in experimentally infected vaccinated animals, while in naturally infected vaccinated calves, the inhibitory activity appeared to be linked to a greater degree with IgA. These results suggest that in contrast to schistosomiasis in humans, IgG antibodies in calves with schistosomiasis may exhibit inhibitory functions toward GST enzymatic activity or have a modulatory effect on IgA antibody properties. Furthermore, sera from animals immunized with recombinantS. bovis28GST recognized the nativeS. mattheei28GST and achieved comparable levels of inhibition of activity of recombinantS. bovis28GST andS. matthei28GST, indicating the presence of cross-reactive epitopes on these two molecules.
Expression of Virulence ofMycobacterium tuberculosiswithin Human Monocytes: Virulence Correlates with Intracellular Growth and Induction of Tumor Necrosis Factor Alpha but Not with Evasion of Lymphocyte-Dependent Monocyte Effector Functions
Authors: Silver Richard F. , Li Qing , Ellner Jerrold J. 
Published: December 2019

ABSTRACTWe assessed the applicability of an in vitro model of low-level infection of human monocytes to the characterization of the virulence of strains of theMycobacterium tuberculosisfamily. Peripheral blood monocytes were infected at a 1:1 ratio with the virulentM. tuberculosisstrain H37Rv, the avirulentM. tuberculosisstrain H37Ra, and the attenuatedM. bovisstrain BCG. Both the percentages of cells infected by the three strains and the initial numbers of intracellular organisms were equivalent, as were levels of monocyte viability up to 7 days following infection. Intracellular growth reflected virulence, as H37Rv replicated in logarithmic fashion throughout the assay, BCG growth reached a plateau at 4 days, and H37Ra did not grow at all. The same patterns of growth were observed following infection of human alveolar macrophages with H37Rv and H37Ra. Monocyte production of tumor necrosis factor alpha was significantly higher following infection with virulent H37Rv than with either BCG or H37Ra. In contrast, there was no clear correlation of interleukin 10 production with virulence. Nonadherent cells of purified-protein-derivative-positive donors mediated equivalent degrees of reduction of the intracellular growth of H37Rv, BCG, and H37Ra. Low-level infection of human monocytes with H37Rv, BCG, and H37Ra thus provides an in vitro model for assessment of the virulence of theseM. tuberculosisfamily strains. Furthermore, it is suggested that the virulence of these strains is expressed primarily by their differing abilities to adapt to the intracellular environment of the mononuclear phagocyte.
Expression ofAnaplasma marginaleMajor Surface Protein 2 Variants during Persistent Cyclic Rickettsemia
Authors: French Dorothy M. , McElwain Terry F. , McGuire Travis C. , Palmer Guy H. 
Published: December 2019

ABSTRACTAnaplasma marginaleis an intraerythrocytic rickettsial pathogen of cattle in which infection persists for the life of the animal. PersistentA. marginaleinfection is characterized by repetitive rickettsemic cycles which we hypothesize reflect emergence ofA. marginaleantigenic variants. In this study, we determined whether variants of major surface protein 2 (MSP-2), a target of protective immunity encoded by a polymorphic multigene family, arise during persistent rickettsemia. By using a quantitative competitive PCR to identify rickettsemic cycles,msp-2transcripts expressed in vivo were isolated from peak rickettsemia of sequential cycles. Cloning and sequencing ofmsp-2cDNA revealed that genetic variants of MSP-2 emerge representing a minimum of four genetic variant types in each cycle during persistent infection. Two-color immunofluorescence using variant-specific antibody showed that emergence of MSP-2 variants resulted in expression of a minimum of three antigenic types of MSP-2 within one rickettsemic cycle. Therefore immune control of each cycle would require responses to an antigenically diverseA. marginalepopulation. These findings demonstrate that polymorphic MSP-2 variants emerge during cyclic rickettsemia in persistentA. marginaleinfection and suggest that emergent variants play an important role in persistence.
Transforming Growth Factor β and Immunosuppression in Experimental Visceral Leishmaniasis
Authors: Rodrigues Virmondes , Santana da Silva João , Campos-Neto Antonio 
Published: December 2019

ABSTRACTHamsters infected withLeishmania donovanidevelop a disease similar to human kala-azar. They present hypergammaglobulinemia, and their T cells do not respond to parasite antigens. This unresponsiveness has been primarily ascribed to defects in antigen-presenting cells (APCs), because these cells are unable to stimulate proliferation of parasite-specific T cells from immunized animals. In this study, we show that APCs (adherent spleen cells) fromL. donovani-infected hamsters produce high levels of the inhibitory cytokine transforming growth factor β (TGF-β). Immunohistochemical studies with an anti-TGF-β monoclonal antibody (MAb) showed that this cytokine is abundantly produced in vivo by the spleen cells of infected animals. In addition, high levels of TGF-β are produced in vitro by infected hamster cells, either spontaneously or after stimulation with parasite antigen or lipopolysaccharide. Furthermore, in vivo-infected adherent cells obtained from spleens ofL. donovani-infected hamsters caused profound inhibition of the in vitro antigen-induced proliferative response of lymph node cells from hamsters immunized with leishmanial antigens. Moreover, this inhibition was totally abrogated by the anti-TGF-β MAb. These results suggest that the immunosuppression observed in visceral leishmaniasis is, at least in part, due to the abundant production of TGF-β during the course of the infection.
GroEL Heat Shock Protein of
Haemophilus ducreyi
: Association with Cell Surface and Capacity To Bind to Eukaryotic Cells
Authors: Frisk A. , Ison C. A. , Lagergård T. 
Published: December 2019

ABSTRACT

The
Haemophilus ducreyi
homolog of GroEL, a 58.5-kDa heat shock protein (Hsp), is a dominant protein produced not only in response to heat stress but also under in vitro growth conditions. Extracellular localization of the 58.5-kDa Hsp was investigated by whole-cell enzyme-linked immunosorbent assay (ELISA) and immunoelectron microscopy and in supernatants of washed bacteria by immunoblotting with a
Haemophilus ducreyi
GroEL-specific mouse monoclonal antibody (BB11). To investigate binding of the Hsp to eukaryotic cells, the 58.5-kDa Hsp was purified by ion-exchange and size exclusion chromatography; incubated with HEp-2 cells, HeLa cells, and human fibroblasts; and then analyzed by immunoblotting. Direct involvement of the 58.5-kDa Hsp in the adherence of
H. ducreyi
to HEp-2 cells was investigated by using an inhibition assay. An epitope of the 58.5-kDa Hsp was detected by whole-cell ELISA on all of the strains tested, suggesting that it is associated with the cell surface. This was also supported by immunoelectron microscopy results. In supernatants of washed bacteria, the 58.5-kDa Hsp was detected by immunoblotting after 10 h of cultivation. The 58.5-kDa Hsp bound to the eukaryotic cells tested but exerted only limited (about 20%) inhibition of
H. ducreyi
adherence to HEp-2 cells. These results demonstrate that the 58.5-kDa Hsp of
H. ducreyi
is associated with the bacterial surface, binds to eukaryotic cells, and partially influences
H. ducreyi
adherence to HEp-2 cells, indicating possible involvement of the 58.5-kDa Hsp in the attachment of bacteria to host cells and to each other.
Sulfated Polysaccharides and a Synthetic Sulfated Polymer Are Potent Inhibitors of
Chlamydia trachomatis
Infectivity In Vitro but Lack Protective Efficacy in an In Vivo Murine Model of Chlamydial Genital Tract Infection
Authors: Su Hua , Caldwell Harlan D. 
Published: December 2019

ABSTRACT

Heparin, dextran sulfate, pentosan polysulfate, and a sulfated synthetic copolymer of acrylic acid and vinyl alcohol were shown to be potent inhibitors of
Chlamydia trachomatis
infectivity for cultured human epithelial cells. Despite their potent antichlamydial activity in vitro, neither heparin nor dextran sulfate was effective in inhibiting the infectivity of
C. trachomatis
in a murine model of chlamydial infection of the female genital tract.
Cytokine Kinetics and Other Host Factors in Response to Pneumococcal Pulmonary Infection in Mice
Authors: Bergeron Yves , Ouellet Nathalie , Deslauriers Anne-Marie , Simard Marie , Olivier Martin , Bergeron Michel G. 
Published: December 2019

ABSTRACTThere is a need for more insight into the pathogenesis ofStreptococcus pneumoniaepneumonia, as the fatality rate associated with this disease remains high despite appropriate antibiotherapy. The host response to pneumococci was investigated after intranasal inoculation of CD1 mice with 107log-phase CFU of bacteria. We identified five major pathogenesis steps from initial infection to death. In step 1 (0 to 4 h), there was ineffective phagocytosis by alveolar macrophages, with concurrent release of tumor necrosis factor alpha (TNF), interleukin-6 (IL-6), and nitric oxide (NO) in bronchoalveolar lavage (BAL) fluid, TNF, IL-6, and interleukin-1 alpha (IL-1) in lung tissues, and IL-6 in serum, which were associated with tachypnea and hemoconcentration. In step 2 (4 to 24 h), bacterial growth in alveoli and polymorphonuclear cell recruitment from bloodstream to lung tissue (high myeloperoxidase levels) to alveoli were associated with high release of all three cytokines and leukotriene B4(LTB4) in tissue and BAL fluid, as well as transient spillover of IL-1 in serum. In step 3 (24 to 48 h), despite downregulation of TNF and IL-1 in BAL fluid and lungs, there was appearance of injury to alveolar ultrastructure, edema to interstitium, and increase in lung weight as well as regeneration of type II pneumocytes and increased secretion of surfactant; bacteria progressed from alveoli to tissue to blood, and body weight loss occurred. In step 4 (48 to 72 h), strong monocyte recruitment from blood to alveoli was associated with high NO release in tissue and BAL fluid, but there was also noticeable lymphocyte recruitment and leukopenia; bacteremia was associated with TNF and IL-6 release in blood and thrombocytopenia. In step 5 (72 to 96 h), severe airspace disorganization, lipid peroxidation (high malondialdehyde release in BAL fluid), and diffuse tissue damage coincided with high NO levels; there was further increase in lung weight and bacterial growth, loss in body weight, and high mortality rate. Delineation of the sequential steps that contribute to the pathogenesis of pneumococcal pneumonia may generate markers of evolution of disease and lead to better targeted intervention.
Different Classes of Proteoglycans Contribute to the Attachment of
Borrelia burgdorferi
to Cultured Endothelial and Brain Cells
Authors: Leong John M. , Wang Hong , Magoun Loranne , Field Jodie A. , Morrissey Pamela E. , Robbins Douglas , Tatro Jeffrey B. , Coburn Jenifer , Parveen Nikhat 
Published: December 2019

ABSTRACT

The Lyme disease spirochete,
Borrelia burgdorferi
, infects multiple tissues, such as the heart, joint, skin, and nervous system and has been shown to recognize heparan sulfate and dermatan sulfate proteoglycans. In this study, we examined the contribution of different classes of proteoglycans to the attachment of the infectious
B. burgdorferi
strain N40 to several immortalized cell lines and primary cultured cells, including endothelial cells and brain cells. Bacterial attachment was inhibited by exogenous proteoglycans or by treatment of host cells with inhibitors of proteoglycan synthesis or sulfation, indicating that proteoglycans play a critical role in bacterial binding to diverse cell types. Binding to primary bovine capillary endothelial cells or a human endothelial cell line was also inhibited by digestion with heparinase or heparitinase but not with chondroitinase ABC. In contrast, binding to glial cell-enriched brain cell cultures or to a neuronal cell line was inhibited by all three lyases. Binding of strain N40 to immobilized heparin could be completely inhibited by dermatan sulfate, and conversely, binding to dermatan sulfate could be completely blocked by heparin. As measured by 50% inhibitory dose, heparin was a better inhibitor of binding than dermatan sulfate, regardless of whether the substrate was heparin or dermatan sulfate. These results are consistent with the hypotheses that the species of proteoglycans recognized by
B. burgdorferi
vary with cell type and that bacterial recognition of different proteoglycans is mediated by the same bacterial molecule(s).
Immune Responses of Specific-Pathogen-Free Mice to Chronic
Helicobacter pylori
(Strain SS1) Infection
Authors: Ferrero Richard L. , Thiberge Jean-Michel , Huerre Michel , Labigne Agnès 
Published: December 2019

ABSTRACT

A model permitting the establishment of persistent
Helicobacter pylori
infection in mice was recently described. To evaluate murine immune responses to
H. pylori
infection, specific-pathogen-free Swiss mice (
n
= 50) were intragastrically inoculated with 1.2 × 10
7
CFU of a mouse-adapted
H. pylori
isolate (strain SS1). Control animals (
n
= 10) received sterile broth medium alone. Animals were sacrificed at various times, from 3 days to 16 weeks postinoculation (p.i.). Quantitative culture of gastric tissue samples from inoculated mice demonstrated bacterial loads of 4.0 × 10
4
to 8 × 10
6
CFU per g of tissue in the animals. Infected mice had
H. pylori
-specific immunoglobulin M (IgM) and IgG antibodies in serum (at day 3 p.i.) and IgG and IgA antibodies in their gastric contents (weeks 4 and 16 p.i.) and saliva (week 16 p.i.). Mucosal IgM antibodies were not detected. Histological examination of the gastric mucosae from control and infected mice revealed mild chronic gastritis, characterized by the presence of polymorphoneutrophil cell infiltrates and submucosal lymphoid aggregates, in infected animals at 16 weeks p.i. Differences in the quantities of IgG1 and IgG2a subclass antibodies detected in the sera of mouse strains (Swiss, BALB/c, and C57BL/6) infected by
H. pylori
suggested that host factors influence the immune responses induced against this bacterium in the host. In conclusion, immune responses to
H. pylori
infection in mice, like those in chronically infected humans, appear to be ineffective in resolving the infection.