bluuebunny/crossref_metadata_2025_split huggingface dataset:
MHC Class I Recognition by NK Receptors in the Ly49 Family Is Strongly Influenced by the β2-Microglobulin Subunit
Authors: Michaëlsson Jakob , Achour Adnane , Rölle Alexander , Kärre Klas 
Published: April 2014

AbstractNK cell recognition of targets is strongly affected by MHC class I specific receptors. The recently published structure of the inhibitory receptor Ly49A in complex with H-2Dd revealed two distinct sites of interaction in the crystal. One of these involves the α1, α2, α3, and β2-microglobulin (β2m) domains of the MHC class I complex. The data from the structure, together with discrepancies in earlier studies using MHC class I tetramers, prompted us to study the role of the β2m subunit in MHC class I-Ly49 interactions. Here we provide, to our knowledge, the first direct evidence that residues in the β2m subunit affect binding of MHC class I molecules to Ly49 receptors. A change from murine β2m to human β2m in three different MHC class I molecules, H-2Db, H-2Kb, and H-2Dd, resulted in a loss of binding to the receptors Ly49A and Ly49C. Analysis of the amino acids involved in the binding of Ly49A to H-2Dd in the published crystal structure, and differing between the mouse and the human β2m, suggests the cluster formed by residues Lys3, Thr4, Thr28, and Gln29, as a potentially important domain for the Ly49A-H-2Dd interaction. Another possibility is that the change of β2m indirectly affects the conformation of distal parts of the MHC class I molecule, including the α1 and α2 domains of the heavy chain.
Augmentation in Expression of Activation-Induced Genes Differentiates Memory from Naive CD4+ T Cells and Is a Molecular Mechanism for Enhanced Cellular Response of Memory CD4+ T Cells
Authors: Liu Kebin , Li Yu , Prabhu Vinayakumar , Young Lynn , Becker Kevin G. , Munson Peter J. , Weng Nan-ping 
Published: April 2014

AbstractIn an attempt to understand the molecular basis for the immunological memory response, we have used cDNA microarrays to measure gene expression of human memory and naive CD4+ T cells at rest and after activation. Our analysis of 54,768 cDNA clones provides the first glimpse into gene expression patterns of memory and naive CD4+ T cells at the genome-scale and reveals several novel findings. First, memory and naive CD4+ T cells expressed similar numbers of genes at rest and after activation. Second, we have identified 14 cDNA clones that expressed higher levels of transcripts in memory cells than in naive cells. Third, we have identified 135 (130 known genes and 5 expressed sequence tags) up-regulated and 68 (42 known genes and 26 expressed sequence tags) down-regulated cDNA clones in memory CD4+ T after in vitro stimulation with anti-CD3 plus anti-CD28. Interestingly, the increase in mRNA levels of up-regulated genes was greater in memory than in naive CD4+ T cells after in vitro stimulation and was higher with anti-CD3 plus anti-CD28 than with anti-CD3 alone in both memory and naive CD4+ T cells. Finally, the changes in expression of actin and cytokine genes identified by cDNA microarrays were confirmed by Northern and protein analyses. Together, we have identified ∼200 cDNA clones whose expression levels changed after activation and suggest that the level of expression of up-regulated genes is a molecular mechanism that differentiates the response of memory from naive CD4+ T cells.
Bcl-2 Targets Protein Phosphatase 1α to Bad
Authors: Ayllón Verónica , Cayla Xavier , García Alphonse , Roncal Fernando , Fernández Raul , Albar Juan Pablo , Martínez-A. Carlos , Rebollo Angelita 
Published: April 2014

Abstract
The diverse forms of protein phosphatase 1 (PP1) in vivo result from the association of the catalytic subunit with different regulatory subunits. We recently have described that PP1α is a Ras-activated Bad phosphatase that regulates IL-2 deprivation-induced apoptosis. With the yeast two-hybrid system, GST fusion proteins, indirect immunofluorescence, and coimmunoprecipitation, we found that Bcl-2 interacts with PP1α and Bad. In contrast, Bad did not interact with 14-3-3 protein. Bcl-2 depletion decreased phosphatase activity and association of PP1α to Bad. Bcl-2 contains the RIVAF motif, analogous to the well characterized R/KXV/IXF consensus motif shared by most PP1-interacting proteins. This sequence is involved in the binding of Bcl-2 to PP1α. Disruption of Bcl-2/PP1α association strongly decreased Bcl-2 and Bad-associated phosphatase activity and formation of the trimolecular complex. These results suggest that Bcl-2 targets PP1α to Bad.
Role of Chemokines and Formyl Peptides in Pneumococcal Pneumonia-Induced Monocyte/Macrophage Recruitment
Authors: Fillion Isabelle , Ouellet Nathalie , Simard Marie , Bergeron Yves , Sato Sachiko , Bergeron Michel G. 
Published: April 2014

AbstractHost-derived chemoattractant factors are suggested to play crucial roles in leukocyte recruitment elicited by inflammatory stimuli in vitro and in vivo. However, in the case of acute bacterial infections, pathogen-derived chemoattractant factors are also present, and it has not yet been clarified how cross-talk between chemoattractant receptors orchestrates diapedesis of leukocytes in this context of complex chemoattractant arrays. To investigate the role of chemokine (host-derived) and formyl peptide (pathogen-derived) chemoattractants in leukocyte extravasation in life-threatening infectious diseases, we used a mouse model of pneumococcal pneumonia. We found an increase in mRNA expression of eight chemokines (RANTES, macrophage-inflammatory protein (MIP)-1α, MIP-1β, MIP-2, IP-10, monocyte chemoattractant protein (MCP)-1, T cell activation 3, and KC) within the lungs during the course of infection. KC and MIP-2 protein expression closely preceded pulmonary neutrophil recruitment, whereas MCP-1 protein production coincided more closely than MIP-1α with the kinetics of macrophage infiltration. In situ hybridization of MCP-1 mRNA suggested that MCP-1 expression started at peribronchovascular regions and expanded to alveoli-facing epithelial cells and infiltrated macrophages. Interestingly, administration of a neutralizing Ab against MCP-1, RANTES, or MIP-1α alone did not prevent macrophage infiltration into infected alveoli, whereas combination of the three Abs significantly reduced macrophage infiltration without affecting neutrophil recruitment. The use of an antagonist to N-formyl peptides, N-t-Boc-Phe-d-Leu-Phe-d-Leu-Phe, reduced both macrophages and neutrophils significantly. These data demonstrate that a complex chemokine network is activated in response to pulmonary pneumococcal infection, and also suggest an important role for fMLP receptor in monocyte/macrophage recruitment in that model.
The Differential Roles of LFA-1 and Mac-1 in Host Defense Against Systemic Infection with Streptococcus pneumoniae
Authors: Prince Joseph E. , Brayton Cory F. , Fossett Milligan C. , Durand Jennifer A. , Kaplan Sheldon L. , Smith C. Wayne , Ballantyne Christie M. 
Published: April 2014

Abstract
Mice deficient in CD18, which lack all four CD11 integrins, have leukocytosis and increased susceptibility to bacterial infection. To determine the effect of deficiencies in LFA-1 (CD11a/CD18) or Mac-1 (CD11b/CD18) on host defense against systemic bacterial infection, knockout mice were inoculated i.p. with Streptococcus pneumoniae. Increased mortality occurred in both LFA-1−/− (15 of 17 vs 13 of 35 in wild type (WT), p &lt; 0.01) and Mac-1−/− (17 of 34 vs 6 of 25, p &lt; 0.01) mice. All deaths in LFA-1−/− mice occurred after 72 h, whereas most deaths in Mac-1−/− mice occurred within 24–48 h. At 24 h, 21 of 27 Mac-1−/− mice were bacteremic, vs 15 of 25 WT (p = 0.05); no difference was observed between LFA-1−/− and WT. Increased bacteria were recovered from Mac-1−/− spleens at 2 h (p = 0.03) and 6 h (p = 0.002) and from livers (p = 0.001) by 6 h. No difference was observed at 2 h in LFA-1−/− mice, but by 6 h increased bacteria were recovered from spleens (p = 0.008) and livers (p = 0.04). Baseline and peak leukocyte counts were similar between Mac-1−/− and WT, but elevated in LFA-1−/−. At 8 h, peritoneal neutrophils were increased in Mac-1−/−, but not significantly different in LFA-1−/−. Histopathologically, at 24 h Mac-1−/− animals had bacteremia and lymphoid depletion, consistent with sepsis. LFA-1−/− mice had increased incidence of otitis media and meningitis/encephalitis vs WT at 72 and 96 h. Both Mac-1 and LFA-1 play important but distinct roles in host defense to S. pneumoniae.
Immunotherapy of Melanoma: A Dichotomy in the Requirement for IFN-γ in Vaccine-Induced Antitumor Immunity Versus Adoptive Immunotherapy
Authors: Winter Hauke , Hu Hong-Ming , McClain Kimberly , Urba Walter J. , Fox Bernard A. 
Published: April 2014

AbstractThe mechanism by which tumors are rejected following the adoptive transfer of tumor-specific T cells is not well characterized. Recent work has challenged the requirement for cytotoxicity mediated by either the perforin/granzyme or Fas/Fas ligand pathway in T cell-mediated tumor regression. Many reports, including ours, suggest that tumor-specific production of IFN-γ is critical for T cell-mediated tumor regression. However, in most of these studies the evidence to support the role for IFN-γ is only indirect. We have directly examined the requirement for IFN-γ using IFN-γ knockout (GKO) mice. The results show an interesting dichotomy in the requirement for IFN-γ: Antitumor immunity induced by active-specific immunotherapy (vaccination) required IFN-γ, whereas adoptive immunotherapy did not. In GKO mice vaccination with the GM-CSF gene-modified B16BL6-D5 tumor (D5-G6) failed to induce protective immunity against parental D5 tumor. However, adoptive transfer of effector T cells from GKO mice cured 100% of GKO mice with established pulmonary metastases and induced long term antitumor immunity and depigmentation of skin. Furthermore, in vivo neutralization of IFN-γ by mAb treatment or adoptive transfer into IFN-γ receptor knockout mice failed to block the therapeutic efficacy of effector T cells generated from wild-type or perforin knockout mice. Analysis of regressing metastases revealed similar infiltrates of macrophages and granulocytes in both wild-type and GKO mice. These results indicate that in this adoptive immunotherapy model, neither a direct effect on the tumor nor an indirect effect of IFN-γ through activation of myeloid or lymphoid cells is critical for therapeutic efficacy.
Fc Receptor-Mediated Phagocytosis Makes a Significant Contribution to Clearance of Influenza Virus Infections
Authors: Huber Victor C. , Lynch Joyce M. , Bucher Doris J. , Le Jianhua , Metzger Dennis W. 
Published: April 2014

AbstractFc receptors for IgG expressed on macrophages and NK cells are important mediators of opsonophagocytosis and Ab-dependent cell-mediated cytotoxicity. Phagocyte-mediated opsonophagocytosis is pivotal for protection against bacteria, but its importance in recovery from infection with intracellular pathogens is unclear. We have now investigated the role of opsonophagocytosis in protection against lethal influenza virus infection by using FcR γ−/− mice. Absence of the FcR γ-chain did not affect the expression of IFN-γ and IL-10 in the lungs and spleens after intranasal immunization with an influenza subunit vaccine. Titers of serum and respiratory Abs of the IgM, IgG1, IgG2a, and IgA isotypes in FcR γ−/− mice were similar to levels seen in FcR γ+/+ mice. Nevertheless, FcR γ−/− mice were highly susceptible to influenza infection, even in the presence of anti-influenza Abs from immune FcR γ+/+ mice. NK cells were not necessary for the observed Ab-mediated viral clearance, but macrophages were found to be capable of actively ingesting opsonized virus particles. We conclude that Fc receptor-mediated phagocytosis plays a pivotal role in clearance of respiratory virus infections.
γδ T Cell-Deficient Mice Have a Down-Regulated CD8+ T Cell Immune Response AgainstEncephalitozoon cuniculiInfection
Authors: Moretto Magali , Durell Brigit , Schwartzman Joseph D. , Khan Imtiaz A. 
Published: April 2014

Abstractγδ T cells have been reported to play an essential effector role during the early immune response against a wide variety of infectious agents. Recent studies have suggested that the γδ T cell subtype may also be important for the induction of adaptive immune response against certain microbial pathogens. In the present study, an early increase of γδ T cells during murine infection with Encephalitozoon cuniculi, an intracellular parasite, was observed. The role of γδ T cells against E. cuniculi infection was further evaluated by using gene-knockout mice. Mice lacking γδ T cells were susceptible to E. cuniculi infection at high challenge doses. The reduced resistance of δ−/− mice was attributed to a down-regulated CD8+ immune response. Compared with parental wild-type animals, suboptimal Ag-specific CD8+ T cell immunity against E. cuniculi infection was noted in δ−/− mice. The splenocytes from infected knockout mice exhibited a lower frequency of Ag-specific CD8+ T cells. Moreover, adoptive transfer of immune TCRαβ+ CD8+ T cells from the δ−/− mice failed to protect naive CD8−/− mice against a lethal E. cuniculi challenge. Our studies suggest that γδ T cells, due to their ability to produce cytokines, are important for the optimal priming of CD8+ T cell immunity against E. cuniculi infection. This is the first evidence of a parasitic infection in which down-regulation of CD8+ T cell immune response in the absence of γδ T cells has been demonstrated.
Inhibition of Borrelia burgdorferi-Tick Interactions In Vivo by Outer Surface Protein A Antibody
Authors: Pal Utpal , Montgomery Ruth R. , Lusitani Denise , Voet Pierre , Weynants Vincent , Malawista Stephen E. , Lobet Yves , Fikrig Erol 
Published: April 2014

Abstract
Borrelia burgdorferi outer surface protein (Osp) A is preferentially expressed by spirochetes in the Ixodes scapularis gut and facilitates pathogen-vector adherence in vitro. Here we examined B. burgdorferi-tick interactions in vivo by using Abs directed against OspA from each of the three major B. burgdorferi sensu lato genospecies: B. burgdorferi sensu stricto, Borrelia afzelii, and Borrelia garinii. Abs directed against B. burgdorferi sensu stricto (isolate N40) destroy the spirochete and can protect mice from infection. In contrast, antisera raised against OspA from B. afzelii (isolate ACA-1) and B. garinii (isolate ZQ-1) bind to B. burgdorferi N40 but are not borreliacidal against the N40 isolate. Our present studies assess whether these selected OspA Abs interfere with B. burgdorferi-tick attachment in a murine model of Lyme disease with I. scapularis. We examined engorged ticks that had fed on B. burgdorferi N40-infected scid mice previously treated with OspA (N40, ACA-1, ZQ-1, or mAb C3.78) or control Abs. OspA-N40 antisera or mAb C3.78 destroyed B. burgdorferi N40 within the engorged ticks. In contrast, treatment of mice with OspA-ACA-1 and OspA-ZQ-1 antisera did not kill B. burgdorferi N40 within the ticks but did effectively interfere with B. burgdorferi-I. scapularis adherence, thereby preventing efficient colonization of the vector. These studies show that nonborreliacidal OspA Abs can inhibit B. burgdorferi attachment to the tick gut, highlighting the importance of OspA in spirochete-arthropod interactions in vivo.
Gestational Attenuation of Lyme Arthritis Is Mediated by Progesterone and IL-4
Authors: Moro Manuel H. , Bjornsson Johannes , Marietta Eric V. , Hofmeister Erik K. , Germer Jeffrey J. , Bruinsma Elizabeth , David Chella S. , Persing David H. 
Published: April 2014

AbstractInfection of different strains of laboratory mice with the agent of Lyme disease, Borrelia burgdorferi, results in arthritis, the severity of which has been correlated with the dominance of Th1 cytokines. In this study, we demonstrate that changes in B. burgdorferi-specific immunologic responses associated with pregnancy can alter the outcome of Lyme arthritis in mice. Whereas nonpregnant female C3H mice consistently developed severe Lyme arthritis, pregnant mice had a marked reduction in arthritis severity that was associated with a slight reduction in IFN-γ and markedly increased levels of IL-4 production by B. burgdorferi-specific T cells. Similar reductions in arthritis severity and patterns of cytokine production were observed in nonpregnant, progesterone-implanted mice. Ab neutralization of IL-4 in progesterone-implanted mice resulted in severe arthritis. Our results are consistent with the known shift toward Th2 cytokine expression at the maternal-fetal interface, and are the first to show a pregnancy-related therapeutic effect in an infectious model.
Transgenic Cystic Fibrosis Mice Exhibit Reduced Early Clearance of Pseudomonas aeruginosa from the Respiratory Tract
Authors: Schroeder Torsten H. , Reiniger Nina , Meluleni Gloria , Grout Martha , Coleman Fadie T. , Pier Gerald B. 
Published: April 2014

Abstract
The cystic fibrosis (CF) transmembrane conductance regulator (CFTR) has been proposed to be an epithelial cell receptor for Pseudomonas aeruginosa involved in bacterial internalization and clearance from the lung. We evaluated the role of CFTR in clearing P. aeruginosa from the respiratory tract using transgenic CF mice that carried either the ΔF508 Cftr allele or an allele with a Cftr stop codon (S489X). Intranasal application achieved P. aeruginosa lung infection in inbred C57BL/6 ΔF508 Cftr mice, whereas ΔF508 Cftr and S489X Cftr outbred mice required tracheal application of the inoculum to establish lung infection. CF mice showed significantly less ingestion of LPS-smooth P. aeruginosa by lung cells and significantly greater bacterial lung burdens 4.5 h postinfection than C57BL/6 wild-type mice. Microscopy of infected mouse and rhesus monkey tracheas clearly demonstrated ingestion of P. aeruginosa by epithelial cells in wild-type animals, mostly around injured areas of the epithelium. Desquamating cells loaded with P. aeruginosa could also be seen in these tissues. No difference was found between CF and wild-type mice challenged with an LPS-rough mucoid isolate of P. aeruginosa lacking the CFTR ligand. Thus, transgenic CF mice exhibit decreased clearance of P. aeruginosa and increased bacterial burdens in the lung, substantiating a key role for CFTR-mediated bacterial ingestion in lung clearance of P. aeruginosa.
Suppression of Immune Response and Protective Immunity to a Japanese Encephalitis Virus DNA Vaccine by Coadministration of an IL-12-Expressing Plasmid
Authors: Chen Hsin-Wei , Pan Chien-Hsiung , Huan Hwei-Wen , Liau Ming-Yi , Chiang Jen-Ron , Tao Mi-Hua 
Published: April 2014

AbstractIL-12 plays a central role in both innate and acquired immunity and has been demonstrated to potentiate the protective immunity in several experimental vaccines. However, in this study, we show that IL-12 can be detrimental to the immune responses elicited by a plasmid DNA vaccine. Coadministration of the IL-12-expressing plasmid (pIL-12) significantly suppressed the protective immunity elicited by a plasmid DNA vaccine (pE) encoding the envelope protein of Japanese encephalitis virus. This suppressive effect was associated with marked reduction of specific T cell proliferation and Ab responses. A single dose of pIL-12 treatment with plasmid pE in initial priming resulted in significant immune suppression to subsequent pE booster immunization. The pIL-12-mediated immune suppression was dose dependent and evident only when the IL-12 gene was injected either before or coincident with the pE DNA vaccine. Finally, using IFN-γ gene-disrupted mice, we showed that the suppressive activity of the IL-12 plasmid was dependent upon endogenous production of IFN-γ. These results demonstrate that coexpression of the IL-12 gene can sometimes produce untoward effects to immune responses, and thus its application as a vaccine adjuvant should be carefully evaluated.
Transmission Intensity Determines Lymphocyte Responsiveness and Cytokine Bias in Human Lymphatic Filariasis
Authors: King Christopher L. , Connelly Marc , Alpers Michael P. , Bockarie Moses , Kazura James W. 
Published: April 2014

AbstractHumans living in areas where filariasis is endemic vary greatly in their exposure to mosquito-borne infective third-stage larvae (L3) of these parasitic helminths. Because the intensity of exposure to Ags affects T cell differentiation and susceptibility to parasitic infections in murine models, we compared T cell and cytokine responses in 97 residents of two villages in Papua New Guinea, where transmission intensity of Wuchereria bancrofti differed by 63-fold (37 vs 2355 L3 per person per year). Residents of the high transmission village had 4- to 11-fold lower proliferation and IFN-γ responses to filarial Ags, nonparasite Ag, and PHA by PBMC compared with the low transmission village (p &lt; 0.01) even when subjects were matched for intensity of infection. In contrast, filarial Ag-driven IL-5 production was 5.5-fold greater (p &lt; 0.001), and plasma IL-4 and TGF-β levels were 4-fold and 34% higher, respectively, in residents of the high transmission village. IL-4 and IL-10 responses by PBMC differed little according to village, and increased production of the counterregulatory cytokines IL-10 or TGF-β by PBMC did not correlate with weak proliferation and IFN-γ responses. Plasma IL-5, IFN-γ, and IL-10 levels were similar in the two villages. These data demonstrate that the intensity of exposure to L3 affects lymphocyte responsiveness and cytokine bias possibly by a mechanism that alters APC function.
Heterosubtypic Immunity to Influenza A Virus in Mice Lacking IgA, All Ig, NKT Cells, or γδ T Cells
Authors: Benton Kimberly A. , Misplon Julia A. , Lo Chia-Yun , Brutkiewicz Randy R. , Prasad Shiv A. , Epstein Suzanne L. 
Published: April 2014

AbstractThe mechanisms of broad cross-protection to influenza viruses of different subtypes, termed heterosubtypic immunity, remain incompletely understood. We used knockout mouse strains to examine the potential for heterosubtypic immunity in mice lacking IgA, all Ig and B cells, NKT cells (CD1 knockout mice), or γδ T cells. Mice were immunized with live influenza A virus and compared with controls immunized with unrelated influenza B virus. IgA−/− mice survived full respiratory tract challenge with heterosubtypic virus that was lethal to controls. IgA−/− mice also cleared virus from the nasopharynx and lungs following heterosubtypic challenge limited to the upper respiratory tract, where IgA has been shown to play an important role. Ig−/− mice controlled the replication of heterosubtypic challenge virus in the lungs. Acute depletion of CD4+ or CD8+ T cell subsets abrogated this clearance of virus, thus indicating that both CD4+ and CD8+ T cells are required for protection in the absence of Ig. These results in Ig−/− mice indicate that CD4+ T cells can function by mechanisms other than providing help to B cells for the generation of Abs. Like wild-type mice, CD1−/− mice and γδ−/− mice survived lethal heterosubtypic challenge. Acute depletion of CD4+ and CD8+ cells abrogated heterosubtypic protection in γδ−/− mice, but not B6 controls, suggesting a contribution of γδ T cells. Our results demonstrate that the Ab and cellular subsets deficient in these knockout mice are not required for heterosubtypic protection, but each may play a role in a multifaceted response that as a whole is more effective than any of its parts.