bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impaired Secretion of Rat Mannose-Binding Protein Resulting from Mutations in the Collagen-Like Domain
Authors: Heise Charles T. , Nicholls James R. , Leamy C. Edmund , Wallis Russell 
Published: April 2014

AbstractSerum mannose-binding protein (MBP) or mannose-binding lectin initiates the lectin branch of the innate immune response by binding to the surface of potentially pathogenic microorganisms and initiating complement fixation through an N-terminal collagen-like domain. Mutations in this region of human MBP are associated with immunodeficiency resulting from a reduction in the ability of the mutant MBPs to fix complement as well as from reduced serum concentrations. Inefficient secretion of the mutant proteins, which is one possible cause of the reduced serum levels, has been investigated using a mammalian expression system in which each of the naturally occurring human mutations has been recreated in rat serum MBP. The mutations Gly25→Asp and Gly28→Glu disrupt the disulfide-bonding arrangement of the protein and cause at least a 5-fold increase in the half-time of secretion of MBP compared with wild-type rat serum MBP. A similar phenotype, including a 3-fold increase in the half-time of secretion, disruption of the disulfide bonding arrangement, and inefficient complement fixation, is observed when nearby glucosylgalactosyl hydroxylysine residues at positions 27 and 30 are replaced with arginine residues. The results suggest that defective secretion resulting from structural changes in the collagen-like domain is likely to be a contributory factor for MBP immunodeficiency.
Identification of Class II Transcriptional Activator-Induced Genes by Representational Difference Analysis: Discoordinate Regulation of the DNα/DOβ Heterodimer
Authors: Taxman Debra J. , Cressman Drew E. , Ting Jenny P.-Y. 
Published: April 2014

Abstract
Class II transcriptional activator (CIITA) is a master regulator of MHC class II genes, including DR, DP, and DQ, and MHC class II-associated genes DM and invariant chain. To determine the repertoire of genes that is regulated by CIITA and to identify uncharacterized CIITA-inducible genes, we used representational difference analysis. Representational difference analysis screens for differentially expressed transcripts. All CIITA-induced genes were MHC class II related. We have identified the α subunit, DNα, of the class II processing factor DO as an additional CIITA-inducible gene. Northern analysis confirmed that DNα is induced by IFN-γ in 2fTGH fibrosarcoma cells, and CIITA is necessary for high-level expression in B cells. The β subunit, DOβ, is not inducible in fibrosarcoma cells by IFN-γ or exogenous CIITA expression. Moreover, in contrast to other class II genes, DOβ expression remains high in the absence of CIITA in B cells. The promoters for DNα and DOβ contain the highly conserved WXY motifs, and, like other class II genes, expression of both DNα and DOβ requires RFX. These findings demonstrate that both DNα and DOβ are regulated by RFX. However, DNα is defined for the first time as a CIITA-inducible gene, and DOβ as a MHC class II gene whose expression is independent of CIITA.
The Adaptor Protein Gads (Grb2-Related Adaptor Downstream of Shc) Is Implicated in Coupling Hemopoietic Progenitor Kinase-1 to the Activated TCR
Authors: Liu Stanley K. , Smith Christian A. , Arnold Ruediger , Kiefer Friedemann , McGlade C. Jane 
Published: April 2014

AbstractThe hemopoietic-specific Gads (Grb2-related adaptor downstream of Shc) adaptor protein possesses amino- and carboxyl-terminal Src homology 3 (SH3) domains flanking a central SH2 domain and a unique region rich in glutamine and proline residues. Gads functions to couple the activated TCR to distal signaling events through its interactions with the leukocyte-specific signaling proteins SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) and LAT (linker for activated T cells). Expression library screening for additional Gads-interacting molecules identified the hemopoietic progenitor kinase-1 (HPK1), and we investigated the HPK1-Gads interaction within the DO11.10 murine T cell hybridoma system. Our results demonstrate that HPK1 inducibly associates with Gads and becomes tyrosine phosphorylated following TCR activation. HPK1 kinase activity is up-regulated in response to activation of the TCR and requires the presence of its proline-rich motifs. Mapping experiments have revealed that the carboxyl-terminal SH3 domain of Gads and the fourth proline-rich region of HPK1 are essential for their interaction. Deletion of the fourth proline-rich region of HPK1 or expression of a Gads SH2 mutant in T cells inhibits TCR-induced HPK1 tyrosine phosphorylation. Together, these data suggest that HPK1 is involved in signaling downstream from the TCR, and that SH2/SH3 domain-containing adaptor proteins, such as Gads, may function to recruit HPK1 to the activated TCR complex.
Aberrant Trafficking of the B Cell Receptor Ig-αβ Subunit in a B Lymphoma Cell Line
Authors: Condon Colm , Hourihane Sharon L. , Dang-Lawson May , Escribano Jessica , Matsuuchi Linda 
Published: April 2014

Abstract
The B cell Ag receptor (BCR) has two important functions: first, it binds and takes up Ag for presentation to T lymphocytes; and second, it transmits signals that regulate B cell development. Normal expression of the BCR requires the association of the Ag binding subunit, membrane IgM (mIgM), with the signaling component, the Ig-αβ heterodimer. After assembly in the endoplasmic reticulum, the intact BCR travels through the secretory pathway to the cell surface. In this paper, we report two variants of the B lymphoma cell lines, WEHI 279 and WEHI 231, that have both lost the ability to express μ heavy chain and consequently do not express mIgM. However, these variants do express the Ig-αβ heterodimer. In one variant, WEHI 279*, the Ig-αβ remained trapped intracellularly in the absence of mIgM. The other variant, 303.1.5.LM, expressed an aberrantly glycosylated Ig-αβ on the cell surface that was capable of signaling after cross-linking with anti-Ig-β Abs. Further characterization uncovered a point mutation in the 303.1.5.LM mb1 gene that would change a proline for a leucine in the extracellular domain of Ig-α. The 303.1.5.LM Ig-αβ could not associate with a wild-type mIgM after μ heavy chain was reconstituted by DNA transfection. Thus, this mutation could define a region of the Ig-α polypeptide that is important for recognition by the endoplasmic reticulum quality control system, for association with glycosylating enzymes, and for the association of Ig-αβ subunits with mIgM subunits to create a complete BCR complex.
Chlamydia trachomatis Infection of Epithelial Cells Induces the Activation of Caspase-1 and Release of Mature IL-18
Authors: Lu Hang , Shen Caixia , Brunham Robert C. 
Published: April 2014

Abstract
Th1 cells that secrete IFN-γ are particularly important in protective immunity against intracellular pathogens, including chlamydiae, and IL-18 together with IL-12 are strong inducers of IFN-γ secretion by CD4 T cells. Because epithelial cells are known to synthesize IL-18, we investigated the effects of Chlamydia trachomatis infection of human epithelial cell lines on IL-18 secretion. We confirmed that several human epithelial cell lines constitutively express pro-IL-18 and that C. trachomatis infection causes cells to secrete mature IL-18. This was observed for several different serovars and biovars of C. trachomatis. Chlamydia-induced secretion of IL-18 from epithelial cells was regulated at the posttranscriptional level and was dependent on the activation of caspase-1. IL-1α or other secreted factor(s) from chlamydia-infected epithelial cells as well as chlamydial structural component(s) were not involved in inducing IL-18 secretion. Activation of caspase-1 and increased secretion of mature IL-18 was correlated with chlamydial, but not with host protein synthesis. In contrast to epithelial cell lines, fibroblast cell lines constitutively expressed much lower levels of pro-IL-18 and did not secrete mature IL-18 after chlamydial infection even though caspase-1 was activated. Taken together, the results suggest that a chlamydia-derived factor(s) is essential for the secretion of mature IL-18 through caspase-1 activation in infected epithelial cells.
Soluble CD8 Attenuates Cytotoxic T Cell Responses Against Replication-Defective Adenovirus Affording Transprotection of Transgenes In Vivo
Authors: Peng YuFeng , Falck-Pedersen Erik , Elkon Keith B. 
Published: April 2014

Abstract
The T cell coreceptor, CD8, enhances T cell-APC interactions. Because soluble CD8α homodimers can antagonize CD8 T cell activation in vitro, we asked whether secretion of soluble CD8 would effect cytotoxic T cell responses in vivo. Production of soluble CD8 by a replication-defective adenovirus vector allowed persistent virus expression for up to 5 mo in C57BL/6 mice and protected a second foreign transgene from rapid deletion. Soluble CD8 selectively inhibited CD8 T cell proliferation and IFN-γ production and could also attenuate peptide-specific CD8 T cell responses in vivo. These finding suggest that gene vector delivery of soluble CD8 may have therapeutic applications.
Bactericidal and Tumoricidal Activities of Synthetic Peptides Derived from Granulysin
Authors: Wang Zhuo , Choice Edward , Kaspar Allan , Hanson Dennis , Okada Satoshi , Lyu Shu-Chen , Krensky Alan M. , Clayberger Carol 
Published: April 2014

Abstract
Granulysin, a 9-kDa protein localized to human CTL and NK cell granules, is cytolytic against tumor cells and microbes. Molecular modeling predicts that granulysin is composed of five α-helices separated by short loop regions. In this report, synthetic peptides corresponding to the linear granulysin sequence were characterized for lytic activity. Peptides corresponding to the central region of granulysin lyse bacteria, human cells, and synthetic liposomes, while peptides corresponding to the amino or carboxyl regions are not lytic. Peptides corresponding to either helix 2 or helix 3 lyse bacteria, while lysis of human cells and liposomes is dependent on the helix 3 sequence. Peptides in which positively charged arginine residues are substituted with neutral glutamine exhibit reduced lysis of all three targets. While reduction of recombinant 9-kDa granulysin increases lysis of Jurkat cells, reduction of cysteine-containing granulysin peptides decreases lysis of Jurkat cells. In contrast, lysis of bacteria by recombinant granulysin or by cysteine-containing granulysin peptides is unaffected by reducing conditions. Jurkat cells transfected with either CrmA or Bcl-2 are protected from lysis by recombinant granulysin or the peptides. Differential activity of granulysin peptides against tumor cells and bacteria may be exploited to develop specific antibiotics without toxicity for mammalian cells.
Purification and Cloning of an Apoptosis-Inducing Protein Derived from Fish Infected with Anisakis simplex, a Causative Nematode of Human Anisakiasis
Authors: Jung Sang-Kee , Mai Angela , Iwamoto Mitsunori , Arizono Naoki , Fujimoto Daisaburo , Sakamaki Kazuhiro , Yonehara Shin 
Published: April 2014

Abstract
While investigating the effect of marine products on cell growth, we found that visceral extracts of Chub mackerel, an ocean fish, had a powerful and dose-dependent apoptosis-inducing effect on a variety of mammalian tumor cells. This activity was strikingly dependent on infection of the C. mackerel with the larval nematode, Anisakis simplex. After purification of the protein responsible for the apoptosis-inducing activity, we cloned the corresponding gene and found it to be a flavoprotein. This protein, termed apoptosis-inducing protein (AIP), was also found to possess an endoplasmic reticulum retention signal (C-terminal KDEL sequence) and H2O2-producing activity, indicating that we had isolated a novel reticuloplasimin with potent apoptosis-inducing activity. AIP was induced in fish only after infection with larval nematode and was localized to capsules that formed around larvae to prevent their migration to host tissues. Our results suggest that AIP may function to impede nematode infection.
Human Dendritic Cells Discriminate Between Viable and KilledToxoplasma gondiiTachyzoites: Dendritic Cell Activation After Infection with Viable Parasites Results in CD28 and CD40 Ligand Signaling That Controls IL-12-Dependent and -Independent T Cell Production of IFN-γ
Authors: Subauste Carlos S. , Wessendarp Matthew 
Published: April 2014

AbstractWe studied how the interaction between human dendritic cells (DC) and Toxoplasma gondii influences the generation of cell-mediated immunity against the parasite. We demonstrate that viable, but not killed, tachyzoites of T. gondii altered the phenotype of immature DC. DC infected with viable parasites up-regulated the expression of CD40, CD80, CD86, and HLA-DR and down-regulated expression of CD115. These changes are indicative of DC activation induced by T. gondii. Viable and killed tachyzoites had contrasting effects on cytokine production. DC infected with viable T. gondii rather than DC that phagocytosed killed parasites induced secretion of high amounts of IFN-γ by T cells from T. gondii-seronegative donors. IFN-γ production in response to DC infected with viable parasites required CD28 and CD40 ligand (CD40L) signaling. In addition, this IFN-γ response was dependent in part on IL-12 secretion. Production of IL-12 p70 occurred after interaction between T cells and DC infected with viable T. gondii, but not after incubation of T cells with DC plus killed tachyzoites. IL-12 synthesis was inhibited by blockade of CD40L signaling. IL-12-independent IFN-γ production required CD80/CD86-CD28 interaction and, to a lesser extent, CD40-CD40L signaling. Taken together, T. gondii-induced activation of human DC is associated with T cell production of IFN-γ through CD40-CD40L-dependent release of IL-12 and through CD80/CD86-CD28 and CD40-CD40L signaling that mediate IFN-γ secretion even in the absence of bioactive IL-12.
A Role for CD40-CD40 Ligand Interactions in the Generation of Type 1 Cytokine Responses in Human Leprosy
Authors: Yamauchi Paul S. , Bleharski Joshua R. , Uyemura Koichi , Kim Jenny , Sieling Peter A. , Miller Ari , Brightbill Hans , Schlienger Katia , Rea Thomas H. , Modlin Robert L. 
Published: April 2014

AbstractThe interaction of CD40 ligand (CD40L) expressed by activated T cells with CD40 on macrophages has been shown to be a potent stimulus for the production of IL-12, an obligate signal for generation of Th1 cytokine responses. The expression and interaction of CD40 and CD40L were investigated in human infectious disease using leprosy as a model. CD40 and CD40L mRNA and surface protein expression were predominant in skin lesions of resistant tuberculoid patients compared with the highly susceptible lepromatous group. IL-12 release from PBMC of tuberculoid patients stimulated with Mycobacterium leprae was partially inhibited by mAbs to CD40 or CD40L, correlating with Ag-induced up-regulation of CD40L on T cells. Cognate recognition of M. leprae Ag by a T cell clone derived from a tuberculoid lesion in the context of monocyte APC resulted in CD40L-CD40-dependent production of IL-12. In contrast, M. leprae-induced IL-12 production by PBMC from lepromatous patients was not dependent on CD40L-CD40 ligation, nor was CD40L up-regulated by M. leprae. Furthermore, IL-10, a cytokine predominant in lepromatous lesions, blocked the IFN-γ up-regulation of CD40 on monocytes. These data suggest that T cell activation in situ by M. leprae in tuberculoid leprosy leads to local up-regulation of CD40L, which stimulates CD40-dependent induction of IL-12 in monocytes. The CD40-CD40L interaction, which is not evident in lepromatous leprosy, probably participates in the cell-mediated immune response to microbial pathogens.
Inhibition of Human Endothelial Cell Chemokine Production by the Opportunistic Fungal PathogenCryptococcus neoformans
Authors: Mozaffarian Neelufar , Casadevall Arturo , Berman Joan W. 
Published: April 2014

AbstractCryptococcus neoformans is an encapsulated fungal pathogen commonly acquired by inhalation. Extrapulmonary dissemination can lead to infection of the bloodstream and various organs, most commonly resulting in meningoencephalitis. However, infection with C. neoformans is often characterized by a scant inflammatory response. The leukocyte response to infection depends in part upon a gradient of chemotactic factors and adhesion molecules expressed by the host vascular endothelium, yet the inflammatory response of human endothelial cells (EC) to C. neoformans has not been previously investigated. We found that incubation of primary human EC with C. neoformans did not induce chemokine synthesis, and resulted in differential inhibition of cytokine-induced IL-8, IFN-γ-inducible protein-10, and monocyte chemoattractant protein-1. In contrast, C. neoformans had little effect on EC surface expression of the leukocyte ligand, ICAM-1, as determined by flow cytometry. Modulation of chemokine production was dependent on the chemokine under study, the inoculum of C. neoformans used, fungal viability, and cell-cell contact, but independent of cryptococcal strain or encapsulation. These observations suggest a novel mechanism whereby C. neoformans can affect EC function and interfere with the host inflammatory response.
Annexin 1 Binds to U937 Monocytic Cells and Inhibits Their Adhesion to Microvascular Endothelium: Involvement of the α4β1 Integrin
Authors: Solito Egle , Romero Ignacio A. , Marullo Stefano , Russo-Marie Françoise , Weksler Babette B. 
Published: April 2014

AbstractAnnexin 1 (ANX1), a calcium-binding protein, participates in the regulation of early inflammatory responses. Whereas some of its effects depend on intracellular interactions, a growing number of observations indicate that ANX1 may also act via autocrine/paracrine functions following externalization to the outer side of the plasma membrane. We studied the effects of ANX1 on leukocyte adhesion to endothelial cells using as a model system the monocytic cell line U937 and human bone marrow microvascular endothelial cells. Exogenous rANX1, as well as endogenous ANX1 externalized by U937 differentiated in vitro, inhibited monocyte firm adhesion to vascular endothelium. Both binding of ANX1 to U937 cells and ANX1-mediated inhibition of cell adhesion involved the short N-terminal domain of the ANX1 molecule. Under experimental conditions in which ANX1 inhibited U937 adhesion to human bone marrow microvascular endothelial cells, this protein specifically colocalized with the α4 integrin, and a direct interaction between ANX1 and the α4 integrin could be documented by immunoprecipitation experiments. Moreover, ANX1 competed with the endothelial integrin counterreceptor, VCAM-1, for binding to α4 integrin. These results indicate that ANX1 plays an important physiological role in modulating monocyte firm adhesion to the endothelium.
Nitric Oxide Synthase/COX Cross-Talk: Nitric Oxide Activates COX-1 But Inhibits COX-2-Derived Prostaglandin Production
Authors: Clancy Robert , Varenika Branko , Huang Weiqing , Ballou Les , Attur Mukundan , Amin Ashok R. , Abramson Steven B. 
Published: April 2014

AbstractIt is recognized that there is molecular cross-talk between the inflammatory mediators NO and PGs that may regulate tissue homeostasis and contribute to pathophysiological processes. However, the literature is divided with respect to whether NO activates or inhibits PG production. In this study, we sought to determine whether conflicting observations could be accounted for by divergent effects of NO on the two cyclooxygenase (COX) isoforms. Exposure of resting macrophages to NO (30 μM) enhanced PGE2 release by 4.5-fold. This enhancement was inhibited by indomethacin but not by the COX-2 selective inhibitor NS398. To separate the activation of phospholipase A2 and COX, we performed experiments using fibroblasts derived from COX-1-deficient or COX-2-deficient mice. These cells exhibit increased basal PG production, which is due to a constitutively stimulated cytosolic phospholipase A2 and enhanced basal expression of the remaining COX isozyme. The exposure of COX- 2-deficient cells to exogenous NO (10 μM) resulted in a 2.4-fold increase of PGE2 release above controls. Further studies indicated that NO stimulated PGE2 release in COX-2-deficient cells, without altering COX-1 mRNA or protein expression. In contrast, NO inhibited COX-2-derived PGE2 production in both LPS-stimulated macrophages and COX-1 knockout cells. This inhibition was associated with both decreased expression and nitration of COX-2. Thus, these studies demonstrate divergent effects of NO on the COX isoforms. The regulation of PGE production by NO is therefore complex and will depend on the local environment in which these pleiotropic mediators are produced.
Differential Regulation of Prostaglandin E2 and Thromboxane A2 Production in Human Monocytes: Implications for the Use of Cyclooxygenase Inhibitors
Authors: Penglis Peter S. , Cleland Leslie G. , Demasi Maryanne , Caughey Gillian E. , James Michael J. 
Published: April 2014

AbstractThere is an autocrine relationship between eicosanoid and cytokine synthesis, with the ratio of prostaglandin E2 (PGE2)/thromboxane A2 (TXA2) being one of the determinants of the level of cytokine synthesis. In monocytes, cyclooxygenase type 1 (COX-1) activity appears to favor TXA2 production and COX-2 activity appears to favor PGE2 production. This has led to speculation regarding possible linkage of COX isozymes with PGE and TXA synthase. We have studied the kinetics of PGE2 and TXA2 synthesis under conditions that rely on COX-1 or -2 activity. With small amounts of endogenously generated prostaglandin H2 (PGH2), TXA2 synthesis was greater than PGE2. With greater amounts of endogenously generated PGH2, PGE2 synthesis was greater than TXA2. Also, TXA synthase was saturated at lower substrate concentrations than PGE synthase. This pattern was observed irrespective of whether PGH2 was produced by COX-1 or COX-2 or whether it was added directly. Furthermore, the inhibition of eicosanoid production by the action of nonsteroidal anti-inflammatory drugs or by the prevention of COX-2 induction with the p38 mitogen-activated protein kinase inhibitor SKF86002 was greater for PGE2 than for TXA2. It is proposed that different kinetics of PGE synthase and TXA synthase account for the patterns of production of these eicosanoids in monocytes under a variety of experimental conditions. These properties provide an alternative explanation to notional linkage or compartmentalization of COX-1 or -2 with the respective terminal synthases and that therapeutically induced changes in eicosanoid ratios toward predominance of TXA2 may have unwanted effects in long-term anti-inflammatory and anti-arthritic therapy.
Role of Stat3 in Lipopolysaccharide-Induced IL-10 Gene Expression
Authors: Benkhart Elke M. , Siedlar Maciej , Wedel Angela , Werner Thomas , Ziegler-Heitbrock H. W. Loems 
Published: April 2014

AbstractIL-10 is a unique cytokine because it is anti-inflammatory and immunosuppressive. IL-10 is regulated at the level of transcription, but the critical motifs and the relevant transcription factors controlling this gene have remained elusive to date. We now report that a sequence at −120 bp in the human IL-10 promoter binds Stat3 but no other Stat proteins. Mutation of this motif abrogates LPS-induced trans-activation. Overexpression of dominant negative Stat3 suppresses promoter activity, while wild-type Stat3 leads to an enhancement of this activity. Our results show that Stat3, by binding to a single motif in the IL-10 promoter, is controlling expression of the human IL-10 gene.