bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protective Immune Responses Induced by Vaccination with an Expression Genomic Library ofLeishmania major
Authors: Piedrafita David , Xu Damo , Hunter David , Harrison Robert A. , Liew Foo Y. 
Published: December 2022

AbstractTo develop an effective vaccine against the intracellular protozoan parasite Leishmania spp., we investigated the feasibility of expression library immunization (ELI) in the mouse. Genomic expression libraries of L. major were constructed and used to immunize mice. One of the three libraries (L1, with 105 clones) induced a significant protective immune response and delayed the onset of lesion development in highly susceptible BALB/c mice after i.m. immunization, compared with control mice immunized with the empty vector (EV). L1 was then divided into five sublibraries of ∼2 × 104 clones each. Mice immunized with one of the sublibraries (SL1A) developed an even stronger protective effect than that induced by L1. SL1A was further divided into 20 sublibraries (SL2) of ∼103 clones each. One of the SL2 libraries (SL2G) induced a strong protective effect against L. major infection. In direct comparative studies, the protective effect of the sublibraries was in the order of SL2G &gt; SL1A &gt; L1. Lymphoid cells from mice vaccinated with SL2G produced more IFN-γ and NO, compared with cells from control mice injected with EV. Serum from the vaccinated mice also contained more parasite-specific IgG2a Ab, compared with controls. Therefore, these data demonstrate that ELI is feasible against this complex intracellular parasitic infection, by preferentially inducing the development of Th1 responses. Furthermore, by sequential division of the libraries, this approach may be used to enrich and identify protective genes for effective gene vaccination against other parasitic infections.
Cellular Immune Responses Are Essential for the Development of Helicobacter felis-Associated Gastric Pathology
Authors: Roth Kevin A. , Kapadia Sharookh B. , Martin Steven M. , Lorenz Robin G. 
Published: December 2022

Abstract
The bacteria Helicobacter pylori is a major human pathogen that infects over half of the world’s population. Infection initiates a series of changes in the gastric mucosa, beginning with atrophic gastritis and leading in some patients to peptic ulcer disease, mucosa-associated lymphomas, and gastric adenocarcinoma. Although this cascade of events clearly occurs, little is known about the role of the host immune response in disease progression. We have utilized the C57BL/6 Helicobacter felis mouse model to critically analyze the role of the adaptive immune response in the development of Helicobacter-associated gastric pathology. Infection of B and T cell-deficient RAG-1−/− mice or T cell-deficient TCRβδ−/− mice with H. felis resulted in high levels of colonization, but no detectable gastric pathology. Conversely, infection of B cell-deficient μMT mice resulted in severe gastric alterations identical with those seen in immunocompetent C57BL/6-infected mice, including gastric mucosal hyperplasia and intestinal metaplasia. These results demonstrate that the host T cell response is a critical mediator of Helicobacter-associated gastric pathology, and that B cells and their secreted Abs are not the effectors of the immune-mediated gastric pathology seen after H. felis infection. These results indicate that in addition to specific Helicobacter virulence factors, the host immune response is an important determinant of Helicobacter-associated disease.
Regulation of Macrophage Chemokine Expression by Lipopolysaccharide In Vitro and In Vivo
Authors: Kopydlowski Karen M. , Salkowski Cindy A. , Cody M. Joshua , van Rooijen Nico , Major Jennifer , Hamilton Thomas A. , Vogel Stefanie N. 
Published: December 2022

AbstractThe host response to Gram-negative LPS is characterized by an influx of inflammatory cells into host tissues, which is mediated, in part, by localized production of chemokines. The expression and function of chemokines in vivo appears to be highly selective, though the molecular mechanisms responsible are not well understood. All CXC (IFN-γ-inducible protein (IP-10), macrophage inflammatory protein (MIP)-2, and KC) and CC (JE/monocyte chemoattractant protein (MCP)-1, MCP-5, MIP-1α, MIP-1β, and RANTES) chemokine genes evaluated were sensitive to stimulation by LPS in vitro and in vivo. While IL-10 suppressed the expression of all LPS-induced chemokine genes evaluated in vitro, treatment with IFN-γ selectively induced IP-10 and MCP-5 mRNAs, but inhibited LPS-induced MIP-2, KC, JE/MCP-1, MIP-1α, and MIP-1β mRNA and/or protein. Like the response to IFN-γ, LPS-mediated induction of IP-10 and MCP-5 was Stat1 dependent. Interestingly, only the IFN-γ-mediated suppression of LPS-induced KC gene expression was IFN regulatory factor-2 dependent. Treatment of mice with LPS in vivo also induced high levels of chemokine mRNA in the liver and lung, with a concomitant increase in circulating protein. Hepatic expression of MIP-1α, MIP-1β, RANTES, and MCP-5 mRNAs were dramatically reduced in Kupffer cell-depleted mice, while IP-10, KC, MIP-2, and MCP-1 were unaffected or enhanced. These findings indicate that selective regulation of chemokine expression in vivo may result from differential response of macrophages to pro- and antiinflammatory stimuli and to cell type-specific patterns of stimulus sensitivity. Moreover, the data suggest that individual chemokine genes are differentially regulated in response to LPS, suggesting unique roles during the sepsis cascade.
Normal Immune Function of Monocyte-Derived Dendritic Cells from HIV-Infected Individuals: Implications for Immunotherapy
Authors: Chougnet Claire , Cohen Sandra S. , Kawamura Tatsuyoshi , Landay Alan L. , Kessler Harold A. , Thomas Elaine , Blauvelt Andrew , Shearer Gene M. 
Published: December 2022

AbstractDendritic cells (DC) are the most potent cells involved in the generation of primary and secondary immune responses. To assess the feasibility of using autologous DC as immunotherapy for HIV disease, we analyzed a variety of immune parameters using DC isolated from HIV-infected (HIV+) individuals, as well as DC obtained from HIV-uninfected (HIV−) individuals infected in vitro with HIV. After stimulation with recombinant CD40 ligand (CD40LT), cytokine and β-chemokine production were similar by DC from HIV− donors infected in vitro with the CCR5-using HIV Ba-L strain (n = 8) compared with uninfected DC from the same donors. Production of β-chemokines, but not of cytokines, was increased by a CXCR4-using IIIB strain-infected DC (n = 7). Stimulation of HIV-infected DC with CD40LT decreased infection in Ba-L-infected DC, but had no effect on IIIB-infected DC. Consistent with this finding, CD40LT down-regulated CCR5 and up-regulated CXCR4 expression on DC. Monocyte-derived DC were also propagated from 15 HIV+ and 13 HIV− donors. They exhibited similar expression of costimulatory molecules and produced similar amounts of IL-12, IL-10, and β-chemokines, following stimulation. By contrast, stimulated PBMC from HIV+ patients exhibited decreased IL-12 and increased IL-10 production. In summary, phenotype, cytokine secretion, and β-chemokine production by DC from HIV+ individuals were normal. These cells may prove useful in boosting cellular immune responses in HIV+ individuals.
Abnormal NF-κB Activity in T Lymphocytes from Patients with Systemic Lupus Erythematosus Is Associated with Decreased p65-RelA Protein Expression
Authors: Wong Henry K. , Kammer Gary M. , Dennis Greg , Tsokos George C. 
Published: December 2022

AbstractNumerous cellular and biochemical abnormalities in immune regulation have been described in patients with systemic lupus erythematosus (SLE), including surface Ag receptor-initiated signaling events and lymphokine production. Because NF-κB contributes to the transcription of numerous inflammatory genes and has been shown to be a molecular target of antiinflammatory drugs, we sought to characterize the functional role of the NF-κB protein complex in lupus T cells. Freshly isolated T cells from lupus patients, rheumatoid arthritis (RA) patients, and normal individuals were activated physiologically via the TCR with anti-CD3 and anti-CD28 Abs to assess proximal membrane signaling, and with PMA and a calcium ionophore (A23187) to bypass membrane-mediated signaling events. We measured the NF-κB binding activity in nuclear extracts by gel shift analysis. When compared with normal cells, the activation of NF-κB activity in SLE patients was significantly decreased in SLE, but not in RA, patients. NF-κB binding activity was absent in several SLE patients who were not receiving any medication, including corticosteroids. Also, NF-κB activity remained absent in follow-up studies. In supershift experiments using specific Abs, we showed that, in the group of SLE patients who displayed undetectable NF-κB activity, p65 complexes were not formed. Finally, immunoblot analysis of nuclear extracts showed decreased or absent p65 protein levels. As p65 complexes are transcriptionally active in comparison to the p50 homodimer, this novel finding may provide insight on the origin of abnormal cytokine or other gene transcription in SLE patients.
Cutting Edge: Developmental Switches in Chemokine Responses During T Cell Maturation
Authors: Campbell James J. , Pan Junliang , Butcher Eugene C. 
Published: December 2022

AbstractWe show that developmental transitions during thymocyte maturation are associated with dramatic changes in chemotactic responses to chemokines. Macrophage-derived chemokine, a chemokine expressed in the thymic medulla, attracts thymocytes only during a brief window of development, between the late cortical and early medullary stages. All medullary phenotypes (CD4 or CD8 single positive) but not immature thymocytes respond to the medullary stroma-expressed (and secondary lymphoid tissue-associated) chemokines secondary lymphoid-tissue chemokine and macrophage inflammatory protein-3β. The appearance of these responses is associated with the phenotypic stage of cortex to medulla migration and with up-regulation of mRNA for the receptors CCR4 (for macrophage-derived chemokine and thymus and activation-regulated chemokine) and CCR7 (for secondary lymphoid-tissue chemokine and macrophage inflammatory protein-3β). In contrast, most immature and medullary thymocytes migrate to thymus-expressed chemokine, an ability that is lost only with up-regulation of the peripheral homing receptor L-selectin during the latest stages of thymocyte maturation associated with export to the periphery. Developmental switches in chemokine responses may help regulate critical migratory events during T cell development.
Cutting Edge: Activation of NK T Cells by CD1d and α-Galactosylceramide Directs Conventional T Cells to the Acquisition of a Th2 Phenotype
Authors: Singh Nagendra , Hong Seokmann , Scherer David C. , Serizawa Isao , Burdin Nicolas , Kronenberg Mitchell , Koezuka Yasuhiko , Van Kaer Luc 
Published: December 2022

Abstract
NK T cells recognize glycolipid Ags such as α-galactosylceramide (α-GalCer) presented by the MHC class I-like molecule CD1d. In this paper we have studied the in vivo effects of α-GalCer on the generation of adaptive immune responses. Treatment of mice with α-GalCer resulted in rapid activation of NK T cells and production of the cytokines IL-4 and IFN-γ. However, after this initial stimulation, NK T cells became polarized for the production of IL-4. Further, as soon as 6 days after α-GalCer injection, a marked increase in serum IgE levels was observed. Administration of α-GalCer at the time of priming of mice with protein Ag resulted in the generation of Ag-specific Th2 cells and a profound increase in the production of IgE. Collectively, these findings indicate that α-GalCer may be useful for modulating immune responses toward a Th2 phenotype during prophylaxis and therapy.
A Mathematical Model on Germinal Center Kinetics and Termination
Authors: Keşmir Can , De Boer Rob J. 
Published: December 2022

AbstractWe devise a mathematical model to study germinal center (GC) kinetics. Earlier models for GC kinetics are extended by explicitly modeling 1) the cell division history of centroblasts, 2) the Ag uptake by centrocytes, and 3) T cell dynamics. Allowing for T cell kinetics and T-B cell interactions, we study the role of GC T cells in GC kinetics, GC termination, and B cell selection. We find that GC T cells play a major role in GC formation, but that the maintenance of established GC reactions requires very few T cells only. The results therefore suggest that the termination of a GC reaction is largely caused by lack of Ag on the follicular dendritic cells and is hardly influenced by Th cells. Ag consumption by centrocytes is the major factor determining the decay rate of the antigenic stimulus during a GC reaction. Investigating the effect of the Ag dose on GC kinetics, we find that both the total size of the GC and its duration are hardly influenced by the initial amount of Ag. In the model this is due to a buffering effect by competition for limited T cell help and/or competition between proliferating centroblasts.
Assessment of the Role of Determinant Selection in Genetic Control of the Immune Response to Insulin in H-2b Mice
Authors: Thayer Wesley P. , Kraft Jennifer R. , Tompkins S. Mark , Moore Joseph C. , Jensen Peter E. 
Published: December 2022

AbstractThe immune response to insulin is regulated by MHC class II genes. Immune response (Ir) gene-linked low responsiveness to protein Ags can be mediated by the low affinity of potential antigenic determinants for MHC molecules (determinant selection) or by the influence of MHC on the functional T cell repertoire. Strong evidence exists that determinant selection plays a key role in epitope immunodominance and Ir gene-linked unresponsiveness. However, the actual measurement of relative MHC-binding affinities of all potential peptides derived from well-characterized model Ags under Ir gene regulation has been very limited. We chose to take advantage of the simplicity of the structure of insulin to study the mechanism of Ir gene control in H-2b mice, which respond to beef insulin (BINS) but not pork insulin (PINS). Peptides from these proteins, including the immunodominant A(1–14) determinant, were observed to have similar affinities for purified IAb in binding experiments. Functional and biochemical experiments suggested that PINS and BINS are processed with similar efficiency. The T cell response to synthetic pork A(1–14) was considerably weaker than the response to the BINS peptide. We conclude that the poor immunogenicity of PINS in H-2b mice is a consequence of the T cell repertoire rather than differences in processing and presentation.
mdr1a-Encoded P-Glycoprotein Is Not Required for Peripheral T Cell Proliferation, Cytokine Release, or Cytotoxic Effector Function in Mice
Authors: Eisenbraun Michael D. , Miller Richard A. 
Published: December 2022

AbstractThe plasma membrane transport protein P-glycoprotein (P-gp) is expressed by subsets of both CD4+ and CD8+ T cells in mice. The proportion of T cells that express P-gp goes up with age, and the P-gp-expressing subset of the CD4 memory population is hyporesponsive in many in vitro assays. The significance of P-gp expression for T cell function has not been well established, although several reports have suggested that it may promote cytokine export and/or cytotoxic T cell function. To elucidate which T cell functions may require P-gp, we have compared a variety of responses using T cells from wt and P-gp knockout mice. Protein expression and rhodamine-123 efflux studies revealed that peripheral T cells exclusively utilize the mdr1a-encoded isoform rather than the homologous mdr1b or mdr2 isoforms. Comparisons of T cells from mdr1a+/+ and mdr1a−/− mice showed no differences in proliferation or in secretion of IL-2, IL-4, IL-5, IL-10, or IFN-γ in response to polyclonal stimulation. Moreover, mdr1a−/− T cells produced strong allospecific cytotoxic responses comparable to those of wt T cells. Our results show that P-gp is not a necessary component of peripheral T cell functional responses. Further investigation will be needed to determine the significance of P-gp expression in T lymphocytes.
The Role of CTLA-4 in Regulating Th2 Differentiation
Authors: Oosterwegel Mariette A. , Mandelbrot Didier A. , Boyd Scott D. , Lorsbach Robert B. , Jarrett Delma Y. , Abbas Abul K. , Sharpe Arlene H. 
Published: December 2022

AbstractTo examine the role of CTLA-4 in Th cell differentiation, we used two newly generated CTLA-4-deficient (CTLA-4−/−) mouse strains: DO11.10 CTLA-4−/− mice carrying a class II restricted transgenic TCR specific for OVA, and mice lacking CTLA-4, B7.1 and B7.2 (CTLA-4−/− B7.1/B7.2−/− ). When purified naive CD4+ DO11.10 T cells from CTLA-4−/− and wild-type mice were primed and restimulated in vitro with peptide Ag, CTLA-4−/− DO11.10 T cells developed into Th2 cells, whereas wild-type DO11.10 T cells developed into Th1 cells. Similarly, when CTLA-4−/− CD4+ T cells from mice lacking CTLA-4, B7.1, and B7.2 were stimulated in vitro with anti-CD3 Ab and wild-type APC, these CTLA-4−/− CD4+ T cells produced IL-4 even during the primary stimulation, whereas CD4+ cells from B7.1/B7.2−/− mice did not produce IL-4. Upon secondary stimulation, CD4+ T cells from CTLA-4−/− B7.1/B7.2−/− mice secreted high levels of IL-4, whereas CD4+ T cells from B7.1/B7.2−/− mice produced IFN-γ. In contrast to the effects on CD4+ Th differentiation, the absence of CTLA-4 resulted in only a modest effect on T cell proliferation, and increased proliferation of CTLA-4−/− CD4+ T cells was seen only during secondary stimulation in vitro. Administration of a stimulatory anti-CD28 Ab in vivo induced IL-4 production in CTLA-4−/− B7.1/B7.2−/− but not wild-type mice. These studies demonstrate that CTLA-4 is a critical and potent inhibitor of Th2 differentiation. Thus, the B7-CD28/CTLA-4 pathway plays a critical role in regulating Th2 differentiation in two ways: CD28 promotes Th2 differentiation while CTLA-4 limits Th2 differentiation.
Analysis of a 26-kb Region Linked to theMhcin Zebrafish: Genomic Organization of the Proteasome Component β/Transporter Associated with Antigen Processing-2 Gene Cluster and Identification of Five New Proteasome β Subunit Genes
Authors: Murray Brent W. , Sültmann Holger , Klein Jan 
Published: December 2022

AbstractSequencing of zebrafish (Danio rerio) bacterial artificial chromosome and P1 artificial chromosome genomic clone fragments and of cDNA clones has led to the identification of five new loci coding for β subunits of proteasomes (PSMB). Together with the four genes identified previously, nine PSMB genes have now been defined in the zebrafish. Six of the nine genes reside in the zebrafish MHC (Mhc) class I region, four of them reside in a single cluster closely associated with TAP2 on a 26-kb long genomic fragment, and two reside at some distance from the fragment. In addition to homologues of the human genes PSMB5 through PSMB9, two new genes, PSMB11 and PSMB12, have been found for which there are no known corresponding genes in humans. The new genes reside in the PSMB cluster in the Mhc. Homology and promoter region analysis suggest that the Mhc-associated genes might be inducible by IFN-γ. The zebrafish class I region contains representatives of three phylogenetically distinguishable groups of PSMB genes, X, Y, and Z. It is proposed that these genes were present in the ancestral PSMB region before Mhc class I genes became associated with it.
Immunization with Treponema pallidum Outer Membrane Vesicles Induces High-Titer Complement-Dependent Treponemicidal Activity and Aggregation of T. pallidum Rare Outer Membrane Proteins (TROMPs)
Authors: Blanco David R. , Champion Cheryl I. , Lewinski Michael A. , Shang Ellen S. , Simkins Stephen G. , Miller James N. , Lovett Michael A. 
Published: December 2022

Abstract
The purpose of this study was to determine whether immunization with purified outer membrane vesicles (OMV) from Treponema pallidum (T.p.) could elicit Abs capable of killing this organism. It is well established that the immunization of rabbits or mice with killed T.p. or with recombinant T.p. Ags has failed to generate serum killing activity comparable with that of infection-derived immunity. Because of the small amount of T.p. OMV obtainable, a single mouse was immunized with purified OMV. The mouse anti-OMV serum and infection-derived immune rabbit serum (IRS) were compared by reactivities on two-dimensional T.p. immunoblots and by the T.p. immobilization test, a complement-dependent killing assay. Whereas IRS detected &gt;40 Ags, the anti-OMV serum identified only 6 Ags corresponding to proteins identified previously in the outer membrane. T.p. immobilization testing showed that IRS had a 100% killing titer of 1:44 and a 50% killing titer of 1:662. By comparison, the mouse anti-OMV serum had a significantly greater 100% killing titer of 1:1,408 and a 50% killing titer of 1:16,896. Absorption of the anti-OMV serum to remove Ab against outer membrane-associated lipoproteins did not change the 100% killing titer. Freeze-fracture analysis of T.p. incubated in IRS or anti-OMV serum showed that T.p. rare membrane-spanning outer membrane proteins were aggregated. This is the first demonstration of high-titer killing Abs resulting from immunization with defined T.p. molecules; our study indicates that the targets for these Abs are T.p. rare outer membrane proteins.
Enhanced Antigen Transport Across Rat Tracheal Epithelium Induced by Sensitization and Mast Cell Activation
Authors: Yang Ping-Chang , Berin M. Cecilia , Perdue Mary H. 
Published: December 2022

AbstractAg challenge to the apical surface of tracheal epithelium results in a rapid ion secretory response due to the activation of mast cells. The aim of this study was to examine the impact of sensitization and specific Ag challenge on the timing, route, and quantity of Ag transported across tracheal epithelium. After sensitization of rats to a model protein, HRP, tracheal tissues were excised and mounted in Ussing chambers. Tracheas from HRP-sensitized rats, but not naive or OVA-sensitized rats, responded to apical HRP challenge with a rise in short-circuit current (beginning at ∼2 min). Photomicrographs of tissues fixed at 2 min showed that initial transepithelial HRP transport occurred via endosomes and was significantly enhanced in HRP-sensitized rats compared with both control groups. In addition, nonciliated cells, the proportion of which increased after sensitization, contained significantly more HRP than ciliated cells. The hypersensitivity response occurred only in HRP-sensitized and challenged rats and was associated with increased conductance of tracheal epithelium and overall flux of HRP across the tissue. This increased flux of Ag and elevated conductance was not observed in mast cell-deficient Ws/Ws rats. Photomicrographs of tissues fixed 90 min after challenge also showed HRP in the paracellular spaces between adjacent epithelial cells. We conclude that sensitization increases uptake of specific Ag initially via an endosomal transcellular pathway across tracheal epithelium and that, after the hypersensitivity reaction, mast cell-dependent recruitment of the paracellular pathway further augments Ag influx into airway tissue.