bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protective Effect of Vaccination with a Combination of Recombinant Surface Antigen 1 and Interleukin-12 against Toxoplasmosis in Mice
Authors: Letscher-Bru Valerie , Villard Odile , Risse Bernhard , Zauke Michael , Klein Jean-Paul , Kien Truong T. 
Published: March 2020

ABSTRACTWe studied the immune response induced in mice by recombinantToxoplasma gondiisurface antigen 1 (rSAG1) protein, alone or combined with interleukin-12 (IL-12) as an adjuvant, and the protective effect against toxoplasmosis. Immunization with rSAG1 alone induced a specific humoral type 2 immunity and did not protect the animals from infection. In contrast, immunization with rSAG1 plus IL-12 redirected humoral and cellular immunity toward a type 1 pattern and reduced the brain parasite load by 40%.
Increased Capacity for Interleukin-2 Synthesis Parallels Disease Progression in Mice Infected withLeishmania major
Authors: Heinzel Frederick P. , Rerko Ronald M. , Hujer Andrea M. , Maier Richard A. 
Published: March 2020

ABSTRACTLymph node cells of BALB/c mice with progressive leishmaniasis produced sixfold more interleukin-2 (IL-2) in culture than those of healing C57BL/6 mice. IL-2 synthesis also increased in C57BL/6 mice made susceptible by IL-12 or gamma interferon deficiency. However, IL-2 mRNA levels in vivo did not reflect IL-2 production in vitro. Because IL-2 contributes to the pathogenesis of progressive leishmaniasis, the functional significance of these findings should be further explored.
Paclitaxel (Taxol)-Induced Killing ofLeishmania majorin Murine Macrophages
Authors: Doherty T. Mark , Sher Alan , Vogel Stefanie N. 
Published: March 2020

ABSTRACTThe antitumor drug paclitaxel (Taxol) has been demonstrated to be a lipopolysaccharide mimetic in murine macrophages. In this study, the capacity of paclitaxel to activate macrophages to become microbicidal forLeishmania majorwas examined. Paclitaxel and gamma interferon synergized to kill intracellularL. majorinLpsn, but notLpsd, macrophages by a nitric oxide (NO·)-dependent mechanism.
E and P Selectins Are Not Required for Resistance to Severe Murine Lyme Arthritis
Authors: Seiler Kathleen Petri , Ma Ying , Weis John H. , Frenette Paul S. , Hynes Richard O. , Wagner Denisa D. , Weis Janis J. 
Published: March 2020

ABSTRACTBorrelia burgdorferi-induced arthritis in mice is characterized by tendonitis, synovitis, and inflammatory-cell infiltrate, predominantly of neutrophils. Because genetic deficiency in E and P selectins results in delayed recruitment of neutrophils to sites of inflammation, mice with this deficiency were tested for their response to infection withB. burgdorferi. E and P selectins were not required for the control ofB. burgdorferinumbers, nor did deficiency in E and P selectins result in alteration of arthritis severity.
Febrile-Range Temperature Modifies Early Systemic Tumor Necrosis Factor Alpha Expression in Mice Challenged with Bacterial Endotoxin
Authors: Jiang Qingqi , DeTolla Louis , van Rooijen Nico , Singh Ishwar S. , Fitzgerald Bridget , Lipsky Michael M. , Kane Andrew S. , Cross Alan S. , Hasday Jeffrey D. 
Published: March 2020

ABSTRACT
Fever improves survival in acute infections, but the effects of increased core temperature on host defenses are poorly understood. Tumor necrosis factor alpha (TNF-α) is an early activator of host defenses and a major endogenous pyrogen. TNF-α expression is essential for survival in bacterial infections but, if disregulated, can cause tissue injury. In this study, we show that passively increasing core temperature in mice from the basal (36.5 to 37.5°C) to the febrile (39.5 to 40°C) range modifies systemic TNF-α expression in response to bacterial endotoxin (lipopolysaccharide). The early TNF-α secretion rate is enhanced, but the duration of maximal TNF-α production is shortened. We identified Kupffer cells as the predominant source of the excess TNF-α production in the warmer animals. The enhanced early TNF-α production observed at the higher temperature in vivo could not be demonstrated in isolated Kupffer cells or in precision-cut liver slices in vitro, indicating the participation of indirect pathways. Therefore, expression of the endogenous pyrogen TNF-α is regulated by increments in core temperature during fever, generating an enhanced early, self-limited TNF-α pulse.
Microbiological and Inflammatory Effects of Murine Recombinant Interleukin-10 in Two Models of Polymicrobial Peritonitis in Rats
Authors: Montravers Philippe , Maulin Laurence , Mohler Jacqueline , Carbon Claude 
Published: March 2020

ABSTRACTA protective effect of interleukin-10 (IL-10) against the development of lethal shock has been demonstrated in various animal models. In contrast, the immunosuppressant properties of this mediator have been minimally evaluated in low-mortality models of infections. The clinical, microbiological, and inflammatory effects of murine recombinant IL-10 (mrIL-10) therapy were evaluated in two models of peritonitis in rats, which differed in the degree of severity of peritoneal inflammation 3 days after inoculation ofEscherichia coliandBacteroides fragiliswith or withoutEnterococcus faecalis. The severity of the disease remained unchanged compared to that in control animals. A dose-related decrease in the peritoneal phagocyte count was observed in the treated groups compared to the counts in control animals. The subsequent experiments were performed exclusively in the mixed gram-positive–gram negative model, which exhibits an intense and prolonged inflammatory response with similar criteria. The early effects of mrIL-10 (evaluated 6 h after inoculation), repeated injections of mrIL-10 (four doses injected from 0 to 9 h after bacterial challenge), and pretreatment (two doses injected 6 and 3 h before inoculation) were evaluated. The clinical and microbiological parameters remained unchanged in the treated animals. Decreases in the peritoneal phagocyte count and the peritoneal concentration of tumor necrosis factor were observed following repeated injections of mrIL-10. In summary, our data suggest that mrIL-10 does not worsen the manifestations of sepsis. However, these results need to be confirmed in clinical practice.
Antigen-Specific B-Cell Unresponsiveness Induced by ChronicMycobacterium aviumsubsp.paratuberculosisInfection of Cattle
Authors: Waters W. R. , Stabel J. R. , Sacco R. E. , Harp J. A. , Pesch B. A. , Wannemuehler M. J. 
Published: March 2020

ABSTRACTMycobacterium aviumsubsp.paratuberculosisinfection of cattle results in a chronic granulomatous enteritis. Clinical disease (i.e., cachexia, diarrhea, and high fecal bacterial counts) is preceded by a lengthy subclinical stage of disease. The immunologic mechanisms associated with the progression of infected cattle from subclinical to clinical disease are unclear. In this study, a cell proliferation assay was used in combination with flow cytometry to compare peripheral blood lymphocyte responses of cattle with subclinical paratuberculosis to responses of cattle with clinical paratuberculosis. B cells from cattle with subclinical disease proliferated vigorously upon stimulation withM. aviumsubsp.paratuberculosisantigen, with up to 12.4% of the total B cells responding. However, B cells from cattle with clinical disease did not proliferate upon antigen stimulation despite good proliferation in response to concanavalin A stimulation. In addition, these animals had high percentages of peripheral blood B cells. B cells from noninfected animals did not proliferate uponM. aviumsubsp.paratuberculosisantigen stimulation. Thus, it appears that B-cell proliferation is a sensitive indicator of subclinical Johne’s disease. Furthermore, the immunologic mechanisms responsible for the antigen-specific unresponsiveness of peripheral blood B cells may be significant in the eventual progression from subclinical to clinical Johne’s disease in cattle.
PhoP-PhoQ-Regulated Loci Are Required for Enhanced Bile Resistance in
Salmonella
spp
Authors: van Velkinburgh Jennifer C. , Gunn John S. 
Published: March 2020

ABSTRACT

As enteric pathogens,
Salmonella
spp. are resistant to the actions of bile.
Salmonella typhimurium
and
Salmonella typhi
strains were examined to better define the bile resistance phenotype. The MICs of bile for wild-type
S. typhimurium
and
S. typhi
were 18 and 12%, respectively, and pretreatment of log-phase
S. typhimurium
with 15% bile dramatically increased bile resistance. Mutant strains of
S. typhimurium
and
S. typhi
lacking the virulence regulator PhoP-PhoQ were killed at significantly lower bile concentrations than wild-type strains, while strains with constitutively active PhoP were able to survive prolonged incubation with bile at concentrations of >60%. PhoP-PhoQ was shown to mediate resistance specifically to the bile components deoxycholate and conjugated forms of chenodeoxycholate, and the protective effect was not generalized to other membrane-active agents. Growth of both
S. typhimurium
and
S. typhi
in bile and in deoxycholate resulted in the induction or repression of a number of proteins, many of which appeared identical to PhoP-PhoQ-activated or -repressed products. The PhoP-PhoQ regulon was not induced by bile, nor did any of the 21 PhoP-activated or -repressed genes tested play a role in bile resistance. However, of the PhoP-activated or -repressed genes tested, two (
prgC
and
prgH
) were transcriptionally repressed by bile in the medium independent of PhoP-PhoQ. These data suggest that salmonellae can sense and respond to bile to increase resistance and that this response likely includes proteins that are members of the PhoP regulon. These bile- and PhoP-PhoQ-regulated products may play an important role in the survival of
Salmonella
spp. in the intestine or gallbladder.
Defensins Impair Phagocytic Killing by Neutrophils in Biomaterial-Related Infection
Authors: Kaplan S. S. , Heine R. P. , Simmons R. L. 
Published: March 2020

ABSTRACTThe implantation of foreign material carries a risk of infection which frequently is resistant to all treatment short of removing the implant. We have previously shown that these materials activate neutrophils by contact, leading to production of oxygen free radicals accompanied by release of granule products. Such activation further results in depletion of local host defenses, including the capacity of biomaterial-activated neutrophils to kill bacteria. Among the granule products released from neutrophils are small cationic antibacterial peptides (human neutrophil peptides [HNP]) known as defensins. Here we tested the hypothesis that defensins, released from activated neutrophils onto the surface of biomaterials, might play a role in the deactivation of subsequent neutrophil populations. Incubation of neutrophils with purified HNP resulted in a dose-related impairment of stimulus-induced oxygen radical production and of phagocytic killing. Furthermore, fresh neutrophils added to biomaterial-associated neutrophils exhibited impaired phagocytic killing. This impairment could be abrogated by antibody to HNP but not by an irrelevant antibody. Taken together, these observations support the idea that neutrophils activated at a material surface can create, by means of HNP release, an environment hostile to their microbicidal function and that of their infiltrating brethren.
The p47phox−/−Mouse Model of Chronic Granulomatous Disease Has Normal Granuloma Formation and Cytokine Responses toMycobacterium aviumandSchistosoma mansoniEggs
Authors: Segal Brahm H. , Doherty T. Mark , Wynn Thomas A. , Cheever Allen W. , Sher Alan , Holland Steven M. 
Published: March 2020

ABSTRACTChronic granulomatous disease (CGD) is a genetic disorder of NADPH oxidase in which phagocytes are defective in generating reactive oxidants. CGD patients suffer from recurrent infections and exuberant and persistent tissue granuloma formation. We hypothesized that abnormal granulomata in CGD may result from aberrant T-cell-mediated cytokine responses. To assess Th-1-type cytokine responses and granulomata, we challenged p47phox−/−and wild-type mice with avirulent (SmD) or virulent (SmT) variants ofMycobacterium avium2-151. To assess Th-2-type cytokine responses and granulomata, we usedSchistosoma mansonieggs (SME). Mononuclear cells were harvested, and cytokine responses were determined by enzyme-linked immunosorbent assay or reverse transcriptase PCR. Following SmD or SmT challenge, splenocytes from p47phox−/−and wild-type mice generated similar polar Th-1 responses (increased levels of gamma interferon and basal levels of interleukin 4 [IL-4] and IL-5). By 8 weeks after SmT challenge, exuberant splenic granulomata developed in p47phox−/−and wild-type mice. After SME challenge, thoracic lymph node mononuclear cells from p47phox−/−and wild-type mice generated similar mixed Th-1 and Th-2 cytokine responses to SME antigen and concanavalin A. Peak lung granuloma sizes and rates of regression were similar in p47phox−/−and wild-type mice. These results suggest that exuberant granulomatous inflammation in CGD is probably not the result of skewing of T-cell responses toward the Th-1 or Th-2 pole. Appropriate regression of established tissue granulomata in p47phox−/−mice challenged with SME suggests that abnormal granuloma formation in CGD is stimulus dependent and is not an invariant feature of the disease.
Intracellular Tryptophan Pool Sizes May Account for Differences in Gamma Interferon-Mediated Inhibition and Persistence of Chlamydial Growth in Polarized and Nonpolarized Cells
Authors: Kane Colleen D. , Vena Renee M. , Ouellette Scot P. , Byrne Gerald I. 
Published: March 2020

ABSTRACTGamma interferon (IFN-γ) is an important factor in the modulating inhibition of intracellular chlamydial growth and persistence. In human epithelial cells and macrophages, this inhibition is the result of depletion of the essential amino acid tryptophan via the IFN-γ-induced enzyme indoleamine 2,3-dioxygenase. Under these conditions, chlamydiae must successfully compete with the host cell for limited resources in order to maintain viability. We provide evidence to support the hypothesis that the host cell polarization state influences the host-pathogen interplay and outcome of IFN-γ-mediated inhibition. In polarized cells, intracellular soluble tryptophan pools were larger than those in nonpolarized cells despite only small differences in the initial uptake rate of this amino acid compared to that in nonpolarized cells. Furthermore, inChlamydia trachomatis-infected cells, the amounts of tryptophan consumed by the organisms were similar for cells grown in either state. We propose that intracellular tryptophan pool sizes can account for differences in IFN-γ-mediated chlamydial persistence and growth inhibition in polarized and nonpolarized cells. Collectively, these results argue that polarized cell models, which more accurately reflect the conditions in vivo, may be more relevant than conventionally cultured cells in the study of intimate intracellular host-parasite interactions.
AnArcanobacterium(Actinomyces)pyogenesMutant Deficient in Production of the Pore-Forming Cytolysin Pyolysin Has Reduced Virulence
Authors: Jost B. H. , Songer J. G. , Billington S. J. 
Published: March 2020

ABSTRACTPyolysin (PLO), the hemolytic exotoxin expressed byArcanobacterium(Actinomyces)pyogenes, is a member of the thiol-activated cytolysin family of bacterial toxins. Insertional inactivation of theplogene results in loss of expression of PLO with a concomitant loss in hemolytic activity. Theplomutant, PLO-1, has an approximately 1.8-log10reduction in the 50% infectious dose compared to that for wild-typeA. pyogenesin a mouse intraperitoneal infection model. Studies involving cochallenge of wild-type and PLO-1 bacteria resulted in recovery of similar numbers of both strains, suggesting that PLO production is required for survival in vivo. Recombinant, His-tagged PLO (His-PLO) is cytotoxic for mouse peritoneal macrophages and J774 cells in a dose-dependent manner. Protection against challenge withA. pyogenescould be afforded by vaccination with formalin-inactivated His-PLO, suggesting that PLO is a host-protective antigen, as well as a virulence determinant.
Lipopolysaccharides (LPS) of Oral Black-Pigmented Bacteria Induce Tumor Necrosis Factor Production by LPS-Refractory C3H/HeJ Macrophages in a Way Different from That ofSalmonellaLPS
Authors: Kirikae Teruo , Nitta Toshimasa , Kirikae Fumiko , Suda Yasuo , Kusumoto Shoichi , Qureshi Nirofer , Nakano Masayasu 
Published: March 2020

ABSTRACTSome lipopolysaccharide (LPS) preparations from S- or R-form members of the familyEnterobacteriaceaeand oral black-pigmented bacteria (Porphyromonas gingivalisandPrevotella intermedia) are known to activate LPS-refractory C3H/HeJ macrophages. When contaminating proteins are removed from R-form LPS ofEnterobacteriaceaeby repurification, however, this ability is lost. In the present study, we investigated the capacity of LPS fromP. gingivalis,P. intermedia,Salmonella minnesota, andSalmonella abortusequito induce production of tumor necrosis factor (TNF) in gamma interferon-primed C3H/HeJ macrophages before and after repurification.P. abortusequiS-LPS was fractionated by centrifugal partition chromatography into two LPS forms: SL-LPS, having homologous long O-polysaccharide chains, and SS-LPS having short oligosaccharide chains. Prior to repurification, all LPS forms except SL-LPS induced TNF production in both C3H/HeJ and C3H/HeN macrophages. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that repurification removed contaminating protein from the preparations, and repurified SS-LPS andS. minnesotaRa-LPS no longer stimulated TNF production in C3H/HeJ macrophages, although C3H/HeN macrophages remained responsive. In contrast, repurified oral bacterial LPS retained the capacity to induce TNF production in C3H/HeJ macrophages. Oral bacterial LPS preparations also were not antagonized by excess inactive, repurified SL-LPS; Ra-LPS;Rhodobacter sphaeroideslipid A, a competitive LPS antagonist, or paclitaxel, an LPS agonist, and they were comparatively resistant to polymyxin B treatment. Nevertheless, oral bacterial LPS was less toxic tod-galactosamine-treated C3H/HeN mice than was LPS fromSalmonella. These findings indicate that the active molecule(s) and mode of action of LPS fromP. gingivalisandP. intermediaare quite different from those of LPS fromSalmonella.
Strain Variation in Glycosaminoglycan Recognition Influences Cell-Type-Specific Binding by Lyme Disease Spirochetes
Authors: Parveen Nikhat , Robbins Douglas , Leong John M. 
Published: March 2020

ABSTRACT

Lyme disease, a chronic multisystemic disorder that can affect the skin, heart, joints, and nervous system is caused by
Borrelia burgdorferi
sensu lato. Lyme disease spirochetes were previously shown to bind glycosaminoglycans (GAGs). In the current study, the GAG-binding properties of eight Lyme disease strains were determined. Binding by two high-passage HB19 derivatives to Vero cells could not be inhibited by enzymatic removal of GAGs or by the addition of exogenous GAG. The other six strains, which included a different high-passage HB19 derivative (HB19 clone 1), were shown to recognize both heparan sulfate and dermatan sulfate in cell-binding assays, but the relative efficiency of binding to these two GAGs varied among the strains. Strains N40, CA20-2A, and PBi bound predominantly to heparan sulfate, PBo bound both heparan sulfate and dermatan sulfate roughly equally, and VS461 and HB19 clone 1 recognized primarily dermatan sulfate. Cell binding by strain HB19 clone 1 was inhibited better by exogenous dermatan sulfate than by heparin, whereas heparin was the better inhibitor of binding by strain N40. The GAG-binding preference of a Lyme disease strain was reflected in its cell-type-specific binding. Strains that recognized predominantly heparan sulfate bound efficiently to both C6 glioma cells and EA-Hy926 cells, whereas strains that recognized predominantly dermatan sulfate bound well only to the glial cells. The effect of lyase treatment of these cells on bacterial binding was consistent with the model that cell-type-specific binding was a reflection of the GAG-binding preference. We conclude that the GAG-binding preference varies with the strain of Lyme disease spirochete and that this variation influences cell-type-specific binding in vitro.
Listeria monocytogenesPhospholipase C-Dependent Calcium Signaling Modulates Bacterial Entry into J774 Macrophage-Like Cells
Authors: Wadsworth Sandra J. , Goldfine Howard 
Published: March 2020

ABSTRACTListeria monocytogenessecretes several proteins that have been shown to contribute to virulence. Among these is listeriolysin O (LLO), a pore-forming hemolysin that is absolutely required for virulence. Two other virulence factors are phospholipases: a phosphatidylinositol-specific phospholipase C (PI-PLC [plcA]) and a broad-range PLC (plcB). Although mutations inplcAorplcBresulted in small increases in mouse 50% lethal dose (LD50), deletions in both genes resulted in a 500-fold increase in LD50. We have examined the role of these secreted proteins in host intracellular signaling in the J774 macrophage-like cell line. Measurements of cytosolic free calcium ([Ca2+]i) have revealed a rapid spike upon exposure of these cells to wild-typeL. monocytogenes. This is followed by a second peak at 5 min and a third prolonged peak with a maximal [Ca2+]iof 800 to 1,000 nM. The pattern of calcium changes was greatly altered by deletion of any of the three virulence factors. An LLO mutant produced none of these elevations in [Ca2+]i; however, a transient elevation was observed whenever these bacteria entered the cell. A PI-PLC mutant produced a diminished single elevation in [Ca2+]iat 15 to 30 min. A broad-range PLC mutant produced only the first calcium spike. Studies with inhibitors suggested that the first elevation arises from influx of calcium from the extracellular medium through plasma membrane channels and that the second and third elevations come from release of Ca2+from intracellular stores. We observed that internalization of wild-type bacteria and the broad-range PLC mutant was delayed for 5 to 10 min, but the LLO and PI-PLC mutants were internalized rapidly upon infection. Inhibitors that affected calcium signaling changed the kinetics of association of wild-type bacteria with J774 cells, the kinetics of entry, and the efficiency of escape from the primary phagosome.
Mapping of Staphylococcal Enterotoxin A Functional Binding Sites and Presentation by Monoclonal Antibodies and Fusion Proteins
Authors: Mahana Wahib 
Published: March 2020

ABSTRACTStaphylococal enterotoxins (SE) bind with high affinity to major histocompatibility complex (MHC) class II proteins and stimulate large number of T cells via the Vβ region of the T-cell receptor (TCR). To map the epitopes of SE type A (SEA) involved in MHC binding and cell proliferation, 20 specific anti-SEA monoclonal antibodies (MAbs) and two large glutathioneS-transferase fusion proteins corresponding to the amino and carboxy termini, respectively, of SEA were used. The functionality of these antibodies was tested, by MHC binding inhibition, interleukin-2 production, and T-cell proliferation assays. Moreover, I studied the ability of the MAbs to present SEA in vitro to human and murine cells and their reactivity with the two fusion proteins. This study showed that all of the MAbs have a defined effect on one or both immunological properties of SEA and were able to present SEA to human and murine cells. However, one MAb (4H8) recognized SEA but without any interference with its biological activities. When the MAbs were tested to react with the two fusion proteins representing the SEA molecule, all of the MAbs were negative except for two. These results confirmed the presence of two functionally different binding sites of SEA with MHC class II molecules and the importance of the disulfide loop for the mitogenic activity of SEA. I further demonstrated that MAbs can present SEA to immune cells independent of the site recognized by the antibody and that the integrity of the SEA molecule is very important for its functions.