bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proteophosphoglycan, a Major Secreted Product of IntracellularLeishmania mexicanaAmastigotes, Is a Poor B-Cell Antigen and Does Not Elicit a Specific Conventional CD4+T-Cell Response
Authors: Aebischer Toni , Harbecke Dorothee , Ilg Thomas 
Published: December 2019

ABSTRACTSecreted and surface-exposed antigens of intracellular pathogens are thought to provide target structures for detection by the host immune system. The major secreted product of intracellularLeishmania mexicanaamastigotes, a proteophosphoglycan (aPPG), is known to contribute to the establishment of the parasitophorous vacuole and is able to activate complement. aPPG belongs to a novel class of serine- and threonine-richLeishmaniaproteins that are extensively modified by phosphodiester-linked phosphooligosaccharides and terminal mannooligosaccharides. Here we show that mice chronically infected withL. mexicanagenerally do not produce antibodies or Th cells specific for aPPG. Similarly, antibody titers are very low in mice vaccinated with aPPG, and specific CD4+T cells are undetectable. Comparative analyses of otherLeishmaniaglycoconjugates indicate thatL. mexicana-specific carbohydrate structures are poorly immunogenic in mice and that the proteophosphoglycan aPPG behaved immunologically like a carbohydrate. The latter observation is explained by the lack of induction of aPPG-specific CD4+T cells. In contrast, recombinant aPPG peptides stimulate CD4+T-cell responses and high titers of specific antibodies are found in the sera of mice vaccinated with these peptides. Native aPPG is highly resistant to proteinases and apparently cannot be degraded by macrophages. It is concluded that conventional CD4+T cells against the polypeptide backbone of aPPG are not induced because the molecule resists antigen processing due to its extensive and complex carbohydrate modification. The complex glycan chains of aPPG, which exhibit important biological functions for the parasite, may therefore also have evolved to evade detection by the immune system of the host organism.
Infection of Endothelial Cells with
Trypanosoma cruzi
Activates NF-κB and Induces Vascular Adhesion Molecule Expression
Authors: Huang Huan , Calderon Tina M. , Berman Joan W. , Braunstein Vicki L. , Weiss Louis M. , Wittner Murray , Tanowitz Herbert B. 
Published: December 2019

ABSTRACT

Transcriptional activation of vascular adhesion molecule expression, a major component of an inflammatory response, is regulated, in part, by the nuclear factor-κB/Rel (NF-κB) family of transcription factors. We therefore determined whether
Trypanosoma cruzi
infection of endothelial cells resulted in the activation of NF-κB and the induction or increased expression of adhesion molecules. Human umbilical vein endothelial cells (HUVEC) were infected with trypomastigotes of the Tulahuen strain of
T. cruzi
. Electrophoretic mobility shift assays with an NF-κB-specific oligonucleotide and nuclear extracts from
T. cruzi
-infected HUVEC (6 to 48 h postinfection) detected two major shifted complexes. Pretreatment with 50× cold NF-κB consensus sequence abolished both gel-shifted complexes while excess SP-1 consensus sequence had no effect. These data indicate that nuclear extracts from
T. cruzi
-infected HUVEC specifically bound to the NF-κB consensus DNA sequence. Supershift analysis revealed that the gel-shifted complexes were comprised of p65 (RelA) and p50 (NF-κB1). Northern blot analyses demonstrated both the induction of vascular cell adhesion molecule 1 and E-selectin and the upregulation of intercellular adhesion molecule 1 mRNA in HUVEC infected with
T. cruzi
. Immunocytochemical staining confirmed adhesion molecule expression in response to
T. cruzi
infection. These findings are consistent with the hypothesis that the activation of the NF-κB pathway in endothelial cells associated with
T. cruzi
infection may be an important factor in the inflammatory response and subsequent vascular injury and endothelial dysfunction that lead to chronic cardiomyopathy.
Chlamydospore Formation in
Candida albicans
Requires the Efg1p Morphogenetic Regulator
Authors: Sonneborn Anja , Bockmühl Dirk P. , Ernst Joachim F. 
Published: December 2019

ABSTRACT

Chlamydospore formation of the fungal pathogen
Candida albicans
was found to depend on the Efg1 protein, which regulates the yeast-hyphal transition. Isogenic mutants lacking
EFG1
or encoding T206A and T206E variants did not differentiate chlamydospores, while
cek1
,
cph1
, or
tpk2
mutations had no effect. Furthermore, filamentation of
efg1 cph1
double mutants in microaerophilic conditions suggests a novel Efg1p/Cph1p-independent filamentation pathway in
C. albicans.
Deglycosylation of the 45/47-Kilodalton Antigen Complex ofMycobacterium tuberculosisDecreases Its Capacity To Elicit In Vivo or In Vitro Cellular Immune Responses
Authors: Romain Félix , Horn Cynthia , Pescher Pascale , Namane Abdelkader , Riviere Michel , Puzo Germain , Barzu Octavian , Marchal Gilles 
Published: December 2019

ABSTRACTA protection against a challenge withMycobacterium tuberculosisis induced by previous immunization with living attenuated mycobacteria, usually bacillus Calmette-Guérin (BCG). The 45/47-kDa antigen complex (Apa) present in culture filtrates of BCG ofM. tuberculosishas been identified and isolated based on its ability to interact mainly with T lymphocytes and/or antibodies induced by immunization with living bacteria. The protein is glycosylated. A large batch of Apa was purified fromM. tuberculosisculture filtrate to determine the extent of glycosylation and its role on the expression of the immune responses. Mass spectrometry revealed a spectrum of glycosylated molecules, with the majority of species bearing six, seven, or eight mannose residues (22, 24, and 17%, respectively), while others three, four, or five mannoses (5, 9, and 14%, respectively). Molecules with one, two, or nine mannoses were rare (1.5, 3, and 3%, respectively), as were unglycosylated species (in the range of 1%). To eliminate the mannose residues linked to the protein, the glycosylated Apa molecules were chemically or enzymatically treated. The deglycosylated antigen was 10-fold less active than native molecules in eliciting delayed-type hypersensitivity reactions in guinea pigs immunized with BCG. It was 30-fold less active than native molecules when assayed in vitro for its capacity to stimulate T lymphocytes primed in vivo. The presence of the mannose residues on the Apa protein was essential for the antigenicity of the molecules in T-cell-dependent immune responses in vitro and in vivo.
CD4+T-Cell- and Gamma Interferon-Dependent Protection against Murine Malaria by Immunization with Linear Synthetic Peptides from aPlasmodium yoelii17-Kilodalton Hepatocyte Erythrocyte Protein
Authors: Charoenvit Yupin , Majam Victoria Fallarme , Corradin Giampietro , Sacci John B. , Wang Ruobing , Doolan Denise L. , Jones Trevor R. , Abot Esteban , Patarroyo Manuel E. , Guzman Fanny , Hoffman Stephen L. 
Published: December 2019

ABSTRACTMost work on protective immunity against the pre-erythrocytic stages of malaria has focused on induction of antibodies that prevent sporozoite invasion of hepatocytes, and CD8+T-cell responses that eliminate infected hepatocytes. We recently reported that immunization of A/J mice with an 18-amino-acid synthetic linear peptide fromPlasmodium yoeliisporozoite surface protein 2 (SSP2) in TiterMax adjuvant induces sterile protection that is dependent on CD4+T cells and gamma interferon (IFN-γ). We now report that immunization of inbred A/J mice and outbred CD1 mice with each of two linear synthetic peptides from the 17-kDaP. yoeliihepatocyte erythrocyte protein (HEP17) in the same adjuvant also induces protection against sporozoite challenge that is dependent on CD4+T cells and IFN-γ. The SSP2 peptide and the two HEP17 peptides are recognized by B cells as well as T cells, and the protection induced by these peptides appears to be directed against the infected hepatocytes. In contrast to the peptide-induced protection, immunization of eight different strains of mice with radiation-attenuated sporozoites induces protection that is absolutely dependent on CD8+T cells. Data represented here demonstrate that CD4+T-cell-dependent protection can be induced by immunization with linear synthetic peptides. These studies therefore provide the foundation for an approach to pre-erythrocytic-stage malaria vaccine development, based on the induction of protective CD4+T-cell responses, which will complement efforts to induce protective antibody and CD8+T-cell responses.
Human Onchocerciasis and Tetanus Vaccination: Impact on the Postvaccination Antitetanus Antibody Response
Authors: Cooper Philip J. , Espinel Ivan , Wieseman Moira , Paredes Wilson , Espinel Mauricio , Guderian Ronald H. , Nutman Thomas B. 
Published: December 2019

ABSTRACTTo investigate whether helminth infections may affect the efficacy of vaccines by impairing the immune response to nonparasite vaccine antigens, we compared the antibody responses to tetanus toxoid (TT) after tetanus vaccination in 193 subjects withOnchocerca volvulusinfection with 85 comparable noninfected controls. After vaccination, the proportions of subjects in each group attaining protective levels of antitetanus antibodies were similar (96.9% infected versus 97.6% noninfected). Postvaccination increases in antitetanus immunoglobulin G (IgG) and the predominant IgG isotype, IgG1, were equivalent in both groups, as were increases in specific IgG4 and IgE; however, significantly greater increases in specific IgG2 (P< 0.05) and IgG3 (P< 0.001) were observed in the noninfected group. Stratification of theO. volvulus-infected group into two groups representing light and heavy infections revealed a significantly impaired antitetanus IgG response in those with heavy infections compared to those with light infections (P< 0.01) or no infection (P< 0.05). The impact of concurrent intestinal helminth infections on the antitetanus response was also examined; an increased IgG4/IgE ratio was seen in those infected withStrongyloides stercoralis(P< 0.05) and when all helminth infections were combined as a single group (P< 0.05). These findings indicate that concurrent infection withO. volvulusdoes not prevent the development of a protective antitetanus response, although heavierO. volvulusinfections are able to alter the magnitude of this response, and concurrent helminth infections (O. volvulusand intestinal helminths) may alter TT-specific antibody isotype responses.
Bordetella bronchiseptica
-Mediated Cytotoxicity to Macrophages Is Dependent on
bvg
-Regulated Factors, Including Pertactin
Authors: Forde Catrina B. , Shi Xiaoju , Li Jingli , Roberts Mark 
Published: December 2019

ABSTRACT

The effect of
Bordetella bronchiseptica
infection on the viability of murine macrophage-like cells and on primary porcine alveolar macrophages was investigated. The bacterium was shown to be cytotoxic for both cell types, particularly where tight cell-to-cell contacts were established. In addition,
bvg
mutants were poorly cytotoxic for the eukaryotic cells, while a
prn
mutant was significantly less toxic than wild-type bacteria.
B. bronchiseptica
-mediated cytotoxicity was inhibited in the presence of cytochalasin D or cycloheximide, an inhibitor of microfilament-dependent phagocytosis or de novo eukaryotic protein synthesis, respectively. The mechanism of eukaryotic cell death was examined, and cell death was found to occur primarily through a necrotic pathway, although a small proportion of the population underwent apoptosis.
Determination of Antibody Responses of Elderly Adults to All 23 Capsular Polysaccharides after Pneumococcal Vaccination
Authors: Rubins Jeffrey B. , Alter Michael , Loch Joyce , Janoff Edward N. 
Published: December 2019

ABSTRACT

The 23-valent pneumococcal polysaccharide vaccine was formulated to prevent invasive infection in the elderly and other high-risk populations from the most prevalent
Streptococcus pneumoniae
serotypes. However, the immunogenicity of all 23 vaccine polysaccharides has not been fully characterized in elderly adults. We previously reported that whereas the majority of elderly subjects had vigorous immune responses to selected pneumococcal vaccine polysaccharides, a subset of elderly individuals responded to fewer than two of seven vaccine serotypes after immunization. To determine whether these elderly low responders have a general inability to respond to pneumococcal vaccine and to determine whether elderly low responders might be identified by their responses to a few polysaccharides, we measured antibody responses of elderly adults to all 23 vaccine polysaccharides after pneumococcal immunization. As a group, elderly subjects showed a significant rise after immunization in geometric mean antibody levels to all 23 vaccine serotypes. However, when individual rather than group immune responses were assessed, the 23-valent vaccine did not appear to be uniformly immunogenic in these elderly subjects. Eleven elderly subjects (20%) had twofold increases in specific antibody after vaccination to only 5 or fewer of the 23 vaccine polysaccharides, and they did not respond to the most prevalent serotypes causing invasive disease. Antibody responses to serotype 9N were found to reliably distinguish low vaccine responders from other elderly subjects. However, no particular group of vaccine polysaccharides could be used as a marker for adequate immune responses if only postvaccination sera were analyzed.
De Novo Induction of Atherosclerosis by
Chlamydia pneumoniae
in a Rabbit Model
Authors: Fong Ignatius W. , Chiu Brian , Viira Esther , Jang Dan , Mahony James B. 
Published: December 2019

ABSTRACT

Chlamydia pneumoniae
, a bacterial respiratory tract pathogen, has been associated with atherosclerosis in humans.
C. pneumoniae
infection of the respiratory tracts of rabbits fed a noncholesterol diet induced changes of atherosclerosis of the aorta in 6 (26.1%) of 23 animals after a single inoculum at 3 months. Multiple inocula given three times within 6 weeks resulted in grade III atherosclerosis in 8 (34.8%) of 23 rabbits, with an additional 5 (21.7%) showing increased myxoid changes in the intima-media junction and exhibiting 8 (34.8%) focal periaortitis. Control animals inoculated with carrier broth (
n
= 24), HEp-2 cells (
n
= 12), or another respiratory pathogen,
Mycoplasma pneumoniae
(
n
= 32), produced no changes of atherosclerosis after 3 months. The histological changes were dissimilar (fewer foam cells) from those of rabbits fed a 0.5% cholesterol diet but were highly similar to or indistinguishable from changes in rabbits fed a 0.15% cholesterol diet (similar to that of humans). Proinflammatory cytokines and tissue growth factors were more consistently detected in cholesterol-induced aortic lesions than those induced by
C. pneumoniae
. These data are compatible with de novo induction of atherogenesis by
C. pneumoniae
in rabbits and suggest that
C. pneumoniae
may be important in the pathogenesis of atherosclerosis in humans.
Binding of Pili from Uropathogenic
Escherichia coli
to Membranes Secreted by Human Colonocytes and Enterocytes
Authors: Goetz G. S. , Mahmood A. , Hultgren S. J. , Engle M. J. , Dodson K. , Alpers D. H. 
Published: December 2019

ABSTRACT

PapG adhesins mediate the binding of uropathogenic
Escherichia coli
. Although receptors for these adhesins have not been demonstrated in intestinal epithelia, the colonic microflora includes strains of uropathogenic
E. coli
. We now report that surfactant-like particles secreted by the human intestine contain receptors for PapG adhesins and may provide an intestinal habitat for uropathogenic bacteria.
Role of the Amino-Terminal Region of
Porphyromonas gingivalis
Fimbriae in Adherence to Epithelial Cells
Authors: Sojar Hakimuddin T. , Han Yiping , Hamada Nobushiro , Sharma Ashu , Genco Robert J. 
Published: December 2019

ABSTRACT

Porphyromonas gingivalis
fimbriae elicit many responses in eukaryotic cells, including mitogenicity, cytokine production, epithelial cell invasion, and cellular immune response. Specific domains of the major fimbrial protein (FimA) have been shown to be important in triggering some of these functions. The goal of the present study was to identify the domain(s) of
P. gingivalis
FimA responsible for specific interaction with human mucosal epithelial cells. Fimbriated
P. gingivalis
strains have been shown to bind to buccal epithelial cells, whereas nonfimbriated strains bind at low levels or not at all. This and other studies provide evidence that FimA mediates the adherence of
P. gingivalis
to oral epithelial cells. To determine the specific region(s) of
P. gingivalis
FimA involved in epithelial cell binding, specific antipeptide antibodies were used to inhibit the binding of iodinated purified fimbriae as well as the binding of
P. gingivalis
cells to epithelial cells. Antibodies directed against peptides 49 to 68 (VVMANTAGAMELVGKTLAEVK) and 69 to 90 (ALTTELTAENQEAAGLIMTAEP) were found to highly inhibit both the binding of fimbriae and the binding of
P. gingivalis
cells to epithelial cells. The antibody against FimA peptides 69 to 90 also reacted with
P. gingivalis
fimbriae in immunogold labeling and immunoblot analysis, thereby indicating that this peptide domain is exposed on the surface of fimbriae. Our results suggest that the amino-terminal domain corresponding to amino acid residues 49 to 90 of the fimbrillin protein is a major epithelial cell binding domain of
P. gingivalis
fimbriae.
Superantigen Immune Stimulation Evokes Epithelial Monocyte Chemoattractant Protein 1 and RANTES Production
Authors: Jedrzkiewicz Sean , Kataeva Galina , Hogaboam Cory M. , Kunkel Steven L. , Strieter Robert M. , McKay Derek M. 
Published: December 2019

ABSTRACTBacterial superantigens (SAgs) have been implicated in inflammatory disease, and SAg-treated mice have increased jejunal T cells. Here we show that T84 cells (a human epithelial cell line) display increased MCP-1 and RANTES mRNA expression and protein production in response to conditioned medium fromStaphylococcus aureusenterotoxin B (SEB; a model SAg)-activated immune cells. Also, MCP-1 and RANTES mRNAs were increased in jejunal enterocytes isolated from SEB-treated mice. We suggest that T-cell recruitment to the gut following SAg immune activation could be partially due to epithelium-derived chemokines.
Intracellular Delivery of a Cytolytic T-Lymphocyte Epitope Peptide by Pertussis Toxin to Major Histocompatibility Complex Class I without Involvement of the Cytosolic Class I Antigen Processing Pathway
Authors: Carbonetti Nicholas H. , Irish Teresa J. , Chen Carrie H. , O’Connell Colin B. , Hadley Gregg A. , McNamara Ulrike , Tuskan Robert G. , Lewis George K. 
Published: December 2019

ABSTRACTA CD8+cytolytic T-lymphocyte (CTL) response to antigen-presenting cells generally requires intracellular delivery or synthesis of antigens in order to access the major histocompatibility complex (MHC) class I processing and presentation pathway. To test the ability of pertussis toxin (PT) to deliver peptides to the class I pathway for CTL recognition, we constructed fusions of CTL epitope peptides with a genetically detoxified derivative of PT (PT9K/129G). Two sites on the A (S1) subunit of PT9K/129G tolerated the insertion of peptides, allowing efficient assembly and secretion of the holotoxin fusion byBordetella pertussis. Target cells incubated with these fusion proteins were specifically lysed by CTLs in vitro, and this activity was shown to be MHC class I restricted. The activity was inhibited by brefeldin A, suggesting a dependence on intracellular trafficking events, but was not inhibited by the proteasome inhibitors lactacystin andN-acetyl-l-leucyl-l-leucyl-l-norleucinal (LLnL). Furthermore, the activity was present in mutant antigen-presenting cells lacking the transporter associated with antigen processing, which transports peptides from the cytosol to the endoplasmic reticulum for association with MHC class I molecules. PT may therefore bypass the proteasome-dependent cytosolic pathway for antigen presentation and deliver epitopes to class I molecules via an alternative route.
Early Resistance of Interleukin-10 Knockout Mice to Acute Systemic Candidiasis
Authors: Vazquez-Torres Andres , Jones-Carson Jessica , Wagner R. Doug , Warner Thomas , Balish Edward 
Published: December 2019

ABSTRACTIn contrast to immunocompetent controls, interleukin-10 (IL-10) knockout (KO) mice eliminated an experimental intravenous inoculation withCandida albicansfrom their kidneys. Improved clearance ofC. albicansfrom the kidneys of IL-10 KO mice was evident at 24 h after intravenous challenge with the fungus. Conversely, mice with a deletion of the IL-4 cytokine gene were more susceptible to systemic candidiasis than were immunocompetent controls. The hyperresistance of IL-10 KO mice to acute systemic candidiasis did not seem to correlate with nitric oxide-mediated immunity, but rather, it appeared to be associated with more efficient effector function of innate cells, possibly neutrophils. In support of the latter hypothesis, we observed that neutrophils from IL-10 KO mice were more efficient at killingC. albicansblastoconidia and hyphae than were neutrophils from immunocompetent control mice. Neither IL-10 KO nor IL-4 KO mice that were monoassociated withC. albicansfor 4 weeks showed any histologic evidence of systemic candidiasis of endogenous origin. In contrast to systemic candidiasis, we observed no significant (P< 0.05) differences in susceptibility among IL-10 KO, IL-4 KO, and wild-type (immunocompetent) mice to orogastric candidiasis. Our results suggest that IL-10 exerts a negative effect on the early, innate response to acute systemic candidiasis; however, in comparison to immunocompetent control (wild-type) mice, neither IL-10 nor IL-4 deficiency enhanced susceptibility to orogastric candidiasis.
Regulatory T Cells in the Antibody Response toHaemophilus influenzaeType b Polysaccharide
Authors: Breukels Mijke A. , Rijkers Ger T. , Voorhorst-Ogink Marleen M. , Zegers Ben J. M. 
Published: December 2019

ABSTRACTAn in vitro culture system for the induction of an antipolysaccharide response was used to study the cellular interactions which determine the magnitude and nature of this B-lymphocyte response. Healthy adult volunteers were vaccinated with theHaemophilus influenzaetype b polysaccharide (PRP)-tetanus toxoid (TT) conjugate vaccine. Optimal in vitro anti-PRP and anti-TT antibody responses were obtained when B cells were cultured with equal amounts of T cells. The in vitro response is antigen dependent and antigen specific. Culturing with PRP mixed with TT in the presence of T cells induces the highest number of anti-PRP antibody-secreting cells (ASC) (128.4 ×/÷ 15.9 [geometric mean ×/÷ standard deviation] immunoglobulin M [IgM] anti-PRP ASC/106cells; 9.3 ×/÷ 7.6 IgG anti-PRP ASC/106cells). Culturing without T cells induced no anti-PRP ASC; culturing with only PRP, in the presence of T cells, yielded low numbers of anti-PRP ASC (3.7 ×/÷ 5.2 IgM anti-PRP ASC/106cells and 1.2 ×/÷ 2.2 IgG anti-PRP ASC/106cells). Transwell studies showed that the requirements for the antibody response against the polysaccharide are different from those of an antiprotein response. Cytokines formed as a consequence of contact between protein-specific B and T cells were on their own not sufficient to activate TT-specific B cells (8.4 ×/÷ 1.4 anti-TT ASC/106cells); direct contact between T and B cells appeared to be an absolute requirement. However, physical contact between B and T cells in one compartment of the Transwell system resulted in the release of soluble factors able to stimulate B cells in the other compartment to secrete antipolysaccharide antibodies (164 ×/÷ 1.6 anti-PRP ASC/106cells).