bluuebunny/crossref_metadata_2025 huggingface dataset:
B Cell Antigen Receptor-Induced Activation of Akt Promotes B Cell Survival and Is Dependent on Syk Kinase
Authors: Pogue Sarah L. , Kurosaki Tomohiro , Bolen Joseph , Herbst Ronald
Published: April 2014

Signaling through the B cell Ag receptor (BCR) is a key determinant in the regulation of B cell physiology. Depending on additional factors, such as microenvironment and developmental stage, ligation of the BCR can trigger B lymphocyte activation, proliferation, or apoptosis. The regulatory mechanisms determining B cell apoptosis and survival are not known. Using the chicken B lymphoma cell line DT40 as a model system, we investigated the role of the serine/threonine kinase Akt in B cell activation. While parental DT40 cells undergo apoptosis in response to BCR cross-linking, cells overexpressing Akt show a greatly diminished apoptotic response. By contrast, limiting the activation of Akt, either by inhibiting phosphatidylinositol 3-kinase or by ectopic expression of the phospholipid phosphatase MMAC1, results in a significant increase in the percentage of apoptotic cells after BCR cross-linking. Using various DT40 knockout cell lines, we further demonstrate that the tyrosine kinase Syk is required for Akt activation and that Lyn tyrosine kinase inhibits Akt activation. Taken together, the data demonstrate that Akt plays an important role in B cell survival and that Akt is activated in a Syk-dependent pathway.
IL-18 Activates STAT3 in the Natural Killer Cell Line 92, Augments Cytotoxic Activity, and Mediates IFN-γ Production by the Stress Kinase p38 and by the Extracellular Regulated Kinases p44erk-1and p42erk-21
Authors: Kalina Uwe , Kauschat Doerte , Koyama Noriko , Nuernberger Heike , Ballas Karin , Koschmieder Steffen , Bug Gesine , Hofmann Wolf-Karsten , Hoelzer Dieter , Ottmann Oliver G.
Published: April 2014

IL-18 is a regulator of NK cell function which utilizes the serine-threonine IL-1R-associated kinase signal transduction pathway and may activate additional not yet characterized signaling pathways. Here we evaluated IL-18-mediated signal transduction using the human NK cell line NK92 as a model. NK92 cells were shown by RT-PCR to express all three IL-18 receptor chains (IL-18R, accessory protein-like chain, IL-18-binding protein). Stimulation by IL-18 strongly enhanced tyrosine phosphorylation of STAT3 and of the mitogen-activated protein kinases (MAPK) p44erk-1and p42erk-2. In contrast, STAT5 was not activated. The cytolytic activity of NK92 against K562 target cells, which was augmented in a dose-dependent manner by IL-18 in the presence of trace amounts of IL-2, was suppressed by the specific inhibitors of MAPK pathways (PD098059 and SB203580). Similarly, the stimulatory effect of IL-18 on IFN-γ protein production, given in conjunction with IL-2, was counteracted by inhibition of MAPK. IL-18 alone failed to stimulate IFN-γ protein production despite inducing expression of IFN-γ mRNA. IL-2 alone stimulated neither IFN-γ mRNA expression nor IFN-γ protein production. IL-18 did not stimulate proliferation of NK92 cells, either alone or in combination with IL-2 or IL-12. Inhibition of the MAPK pathway did not significantly alter the IL-2- and IL-12-induced proliferation of NK92 cells, whereas the Janus kinase/STAT pathway inhibitor AG490 strongly suppressed proliferation. MAPK activation appears to play a prominent role in IL-18 signaling, being involved in transcription and translation of IL-18-induced IFN-γ mRNA and IL-18-induced cytolytic effects. In contrast, proliferation of NK92 cells is not affected by MAPK p44erk-1 and p42erk-2.
Impaired Natural Killing of MHC Class I-Deficient Targets by NK Cells Expressing a Catalytically Inactive Form of SHP-1
Authors: Lowin-Kropf Bente , Kunz Béatrice , Beermann Friedrich , Held Werner
Published: April 2014

NK cell function is negatively regulated by MHC class I-specific inhibitory receptors. Transduction of the inhibitory signal involves protein tyrosine phosphatases such as SHP-1 (SH2-containing protein tyrosine phosphatase-1). To investigate the role of SHP-1 for NK cell development and function, we generated mice expressing a catalytically inactive, dominant-negative mutant of SHP-1 (dnSHP-1). In this paper we show that expression of dnSHP-1 does not affect the generation of NK cells even though MHC receptor-mediated inhibition is partially impaired. Despite this defect, these NK cells do not kill syngeneic, normal target cells. In fact dnSHP-1-expressing NK cells are hyporesponsive toward MHC-deficient target cells, suggesting that non-MHC-specific NK cell activation is significantly reduced. In contrast, these NK cells mediate Ab-dependent cell-mediated cytotoxicity and prevent the engraftment with β2-microglobulin-deficient bone marrow cells. A similar NK cell phenotype is observed in viable motheaten (mev) mice, which show reduced SHP-1 activity due to a mutation in the Shp-1 gene. In addition, NK cells in both mouse strains show a tendency to express more inhibitory MHC-specific Ly49 receptors. Our results demonstrate the importance of SHP-1 for the generation of functional NK cells, which are able to react efficiently to the absence of MHC class I molecules from normal target cells. Therefore, SHP-1 may play an as-yet-unrecognized role in some NK cell activation pathways. Alternatively, a reduced capacity to transduce SHP-1-dependent inhibitory signals during NK cell development may be compensated by the down-modulation of NK cell triggering pathways.
Fas Ligand-Induced c-Jun Kinase Activation in Lymphoid Cells Requires Extensive Receptor Aggregation But Is Independent of DAXX, and Fas-Mediated Cell Death Does Not Involve DAXX, RIP, or RAIDD
Authors: Villunger Andreas , Huang David C. S. , Holler Nils , Tschopp Juerg , Strasser Andreas
Published: April 2014

Jun kinase signaling can be elicited by death receptor activation, but the mechanism and significance of this event are still unclear. It has been reported that cross-linking Abs to Fas trigger c-Jun N-terminal kinase (JNK) signaling via caspase-mediated activation of MEKK1 (JNK kinase kinase), elevation of ceramide levels or by recruitment of death domain associated protein (DAXX) to Fas. The effect of physiological ligand for Fas on JNK signaling was never investigated, although evidence is accumulating that Fas ligand is able to induce cellular responses distinct from those evoked by Ab-mediated cross-linking of Fas. Therefore, we investigated the effect of Fas ligand on JNK signaling. Like its ability to induce cell death, Fas ligand reliably activated JNK only upon extensive aggregation of the receptor. Although this was partially dependent on caspase activation, DAXX was not required. DAXX and other death receptor-associated proteins, which have been reported to bind directly or indirectly to Fas, such as receptor interacting protein (RIP) and RIP-associated ICH-1/CED-3-homologous protein with a death domain (RAIDD), were shown to be dispensable for Fas ligand-induced apoptosis.
IFN-γ Inhibits Presentation of a Tumor/Self Peptide by CD8α− Dendritic Cells Via Potentiation of the CD8α+ Subset
Authors: Grohmann Ursula , Bianchi Roberta , Belladonna Maria L. , Silla Silvia , Fallarino Francesca , Fioretti Maria C. , Puccetti Paolo
Published: April 2014

Using an in vivo model of tumor/self peptide presentation for induction of class I-restricted skin test reactivity, we have previously shown that a minority population of CD8+ dendritic cells (DC) negatively regulates the induction of T cell reactivity by peptide-loaded CD8− DC in DBA/2 mice. However, the CD8− fraction can be primed by IL-12 to overcome inhibition by the CD8+ subset when the two types of DC are cotransferred into recipient hosts. We report here that exposure of CD8+ DC to IFN-γ greatly enhances their inhibitory activity on Ag presentation by the other subset, blocking the ability of IL-12-treated CD8− DC to overcome suppression. In contrast, IFN-γ has no direct effects on the APC function of the latter cells and does not interfere with IL-12 signaling. The negative regulatory effect triggered by IFN-γ in CD8+ DC appears to involve interference with tryptophan metabolism in vivo. Through tryptophan depletion affecting T cell responses, IFN-γ acting on CD8+ DC may thus contribute to regulation of immunity to tumor/self peptides presented by the CD8− subset.
T Cell Development in TCRβ Enhancer-Deleted Mice: Implications for αβ T Cell Lineage Commitment and Differentiation
Authors: Leduc Isabelle , Hempel William M. , Mathieu Noëlle , Verthuy Christophe , Bouvier Gaëlle , Watrin Françoise , Ferrier Pierre
Published: April 2014

T cell differentiation in the mouse thymus is an intricate, highly coordinated process that requires the assembly of TCR complexes from individual components, including those produced by the precisely timed V(D)J recombination of TCR genes. Mice carrying a homozygous deletion of the TCRβ transcriptional enhancer (Eβ) demonstrate an inhibition of V(D)J recombination at the targeted TCRβ locus and a block in αβ T cell differentiation. In this study, we have characterized the T cell developmental defects resulting from the Eβ−/− mutation, in light of previously reported results of the analyses of TCRβ-deficient (TCRβ−/−) mice. Similar to the latter mice, production of TCRβ-chains is abolished in the Eβ−/− animals, and under these conditions differentiation into cell-surface TCR−, CD4+CD8+ double positive (DP) thymocytes depends essentially on the cell-autonomous expression of TCRδ-chains and, most likely, TCRγ-chains. However, contrary to previous reports using TCRβ−/− mice, a minor population of TCR γδ+ DP thymocytes was found within the Eβ−/− thymi, which differ in terms of T cell-specific gene expression and V(D)J recombinase activity, from the majority of TCR−, αβ lineage-committed DP thymocytes. We discuss these data with respect to the functional role of Eβ in driving αβ T cell differentiation and the mechanism of αβ T lineage commitment.
Increased Frequency of Surface IgA-Positive Plasma Cells in the Intestinal Lamina Propria and Decreased IgA Excretion in Hyper IgA (HIGA) Mice, a Murine Model of IgA Nephropathy with Hyperserum IgA
Authors: Kamata Tadashi , Nogaki Fumiaki , Fagarasan Sidonia , Sakiyama Toshio , Kobayashi Ikei , Miyawaki Shigeki , Ikuta Koichi , Muso Eri , Yoshida Haruyoshi , Sasayama Shigetake , Honjo Tasuku
Published: April 2014

Because abnormalities of mucosal immunity have been suggested in human IgA nephropathy, we examined the involvement of mucosal immunity in IgA deposition to the kidney in hyper IgA (HIGA) mice, which was established as a mouse model for human IgA nephropathy with hyperserum IgA. The number of surface IgA+B220− lymphocytes in the intestinal lamina propria (LP) of HIGA mice increased 2.7-fold at 30 wk of age as compared with those at 10 wk of age, whereas normal mice did not show such increase. The surface IgA+B220− LP lymphocytes spontaneously secreted IgA in culture. Morphological studies showed that the surface IgA+B220− lymphocytes of murine intestinal LP are identical with plasma cells (PCs). About 20% of IgA+B220− PC in LP expressed both Mac-1 and CD19, suggesting that they may derive from peritoneal B-1 cells. Cell cycle study on intestinal IgA-PCs using bromodeoxyuridine revealed no difference between HIGA mice and normal mice, suggesting that the high frequency of IgA-producing PCs in HIGA mice is not due to enhanced proliferation or prolonged survival of IgA-producing PCs in LP. In addition, IgA secretion into the gut lumen of HIGA mice decreased drastically (to one forth) with aging. These data suggest that the increased number of intestinal IgA-producing PCs and the down-regulation of IgA excretion into the intestinal lumen might synergistically contribute to the hyperserum IgA in HIGA mice and resultant IgA deposition to the kidney.
IL-4 Enhances Keratinocyte Expression of CXCR3 Agonistic Chemokines
Authors: Albanesi Cristina , Scarponi Claudia , Sebastiani Silvia , Cavani Andrea , Federici Monica , De Pità Ornella , Puddu Pietro , Girolomoni Giampiero
Published: April 2014

IFN-induced protein of 10 kDa (IP-10), monokine induced by IFN-γ (Mig), and IFN-inducible T-cell α-chemoattractant (I-TAC) belong to the non-glutamate-leucine-arginine motif CXC chemokine family and act solely through the CXCR3 receptor for potent attraction of T lymphocytes. In this study, we evaluated the capacity of the T cell-derived cytokines IL-4, IL-10, and IL-17 to modulate IP-10, Mig, and I-TAC in cultured human keratinocytes and CXCR3 expression in T cells from allergic contact dermatitis (ACD). IL-4, but not IL-10 or IL-17, significantly up-regulated IFN-γ- or TNF-α-induced IP-10, Mig, and I-TAC mRNA accumulation in keratinocytes and increased the levels of IP-10 and Mig in keratinocyte supernatants. Immunohistochemistry of skin affected by ACD revealed that >70% of infiltrating cells were reactive for CXCR3 and that CXCR3 staining colocalized in CD4+ and CD8+ T cells. Nickel-specific CD4+ and CD8+ T cell lines established from ACD skin produced IFN-γ and IL-4 and expressed moderate to high levels of CXCR3. Finally, CXCR3 agonistic chemokines released by stimulated keratinocytes triggered calcium mobilization in skin-derived nickel-specific CD4+ T cells and promoted their migration, with supernatant from keratinocyte cultures stimulated with IFN-γ and IL-4 attracting more efficaciously than supernatant from keratinocytes activated with IFN-γ alone. In conclusion, IL-4 exerts a proinflammatory function on keratinocytes by potentiating IFN-γ and TNF-α induction of IP-10, Mig, and I-TAC, which in turn may determine a prominent recruitment of CXCR3+ T lymphocytes at inflammatory reaction sites.
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

Serum 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

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

The 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

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

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

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

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

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

We 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

The 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

Cryptococcus 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

Annexin 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

It 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

There 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

IL-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.
Adoptively Transferred γδ T Cells Indirectly Regulate Murine Graft-Versus-Host Reactivity Following Donor Leukocyte Infusion Therapy in Mice
Authors: Drobyski William R. , Vodanovic-Jankovic Sanja , Klein John
Published: April 2014

The purpose of this study was to determine whether γδ T cells were able to regulate graft-vs-host (GVH) reactivity mediated by αβ T cells in murine recipients transplanted with MHC-mismatched marrow grafts. Studies were conducted using ex vivo-activated γδ T cells because this was a more clinically relevant strategy, and these cells have been shown to be capable of facilitating alloengraftment without causing GVH disease (GVHD). Coadministration of activated γδ T cells and naive αβ T cells at the time of bone marrow transplantation (BMT) significantly exacerbated GVHD when compared with naive αβ T cells alone. In contrast, when the administration of naive αβ T cells was delayed for 2 wk post-BMT, survival was significantly enhanced in mice transplanted with BM plus activated γδ T cells vs those given marrow cells alone. Mitigation of GVHD by activated γδ T cells occurred only at high doses (150 × 106) and was a unique property of γδ T cells, as activated αβ T cells were incapable of ameliorating the subsequent development of GVHD. Protection from GVHD was not due to the direct inhibition of naive αβ T cells by γδ T cells. Rather, γδ T cells mediated this effect indirectly through donor BM-derived αβ T cells that acted as the proximate regulatory population responsible for the decrease in GVH reactivity. Collectively, these data demonstrate that activated γδ T cells are capable of modulating the ability of MHC-incompatible nontolerant αβ T cells to cause GVHD after allogeneic BMT.
The Effect of a T Cell-Specific NF-κB Inhibitor on In Vitro Cytokine Production and Collagen-Induced Arthritis
Authors: Gerlag Danielle M. , Ransone Lynn , Tak Paul P. , Han Zuoning , Palanki Moorthy , Barbosa Miguel S. , Boyle David , Manning Anthony M. , Firestein Gary S.
Published: April 2014

NF-κB plays a key role in the production of cytokines in inflammatory diseases. The effects of a novel T cell-specific NF-κB inhibitor, SP100030, were evaluated in cultured Jurkat cells and in murine collagen-induced arthritis (CIA). Chemical libraries were screened for NF-κB-inhibitory activity. SP100030, a compound identified in this process, inhibited NF-κB activation in PMA/PHA-activated Jurkat cells by EMSA at a concentration of 1 μM. Jurkat cells and the monocytic cell line THP-1 were transfected with an NF-κB promotor/luciferase construct and activated. SP100030 inhibited luciferase production in the Jurkat cells (IC50 = 30 nM). ELISA and RT-PCR confirmed that IL-2, IL-8, and TNF-α production by activated Jurkat and other T cell lines were inhibited by SP100030. However, cytokine expression was not blocked by the compound in THP-1 cells, fibroblasts, endothelial cells, or epithelial cells. Subsequently, DBA/1J mice were immunized with type II collagen. Treatment with SP100030 (10 mg/kg/day i.p. beginning on day 21) significantly decreased arthritis severity from onset of clinical signs to the end of the study on day 34 (arthritis score, 5.6 ± 1.7 for SP100030 and 9.8 ± 1.5 for control; p < 0.001). Histologic evaluation demonstrated a trend toward improvement in SP100030-treated animals. EMSA of arthritic mouse ankles in CIA showed that synovial NF-κB binding was suppressed in the SP100030-treated mice. SP100030 inhibits NF-κB activation in T cells, resulting in reduced NF-κB-regulated gene expression and decreased CIA. Its selectivity for T cells could provide potent immunosuppression with less toxicity than other NF-κB inhibitors.
α-Glycosylceramides Enhance the Antitumor Cytotoxicity of Hepatic Lymphocytes Obtained from Cancer Patients by Activating CD3−CD56+ NK Cells In Vitro
Authors: Ishihara Soichiro , Nieda Mie , Kitayama Joji , Osada Takuya , Yabe Toshio , Kikuchi Akiko , Koezuka Yasuhiko , Porcelli Steven A. , Tadokoro Kenji , Nagawa Hirokazu , Juji Takeo
Published: April 2014

α-Glycosylceramides, such as α-galactosylceramide and α-glucosylceramide, induce antitumor immunity in various murine cancer models. In the murine hepatic metastasis model, Vα14 TCR+NK1.1+ T cells, which accumulate preferentially in the liver, are considered to play a key role in the induction of antitumor immunity by α-glycosylceramides. We recently reported that Vα24 TCR+ NKT cells, the human homologues of murine Vα14 TCR+NK1.1+cells, are rarely seen among freshly isolated human hepatic lymphocytes. Therefore, it is important to examine whether α-glycosylceramides also enhance the antitumor cytotoxicity of human hepatic lymphocytes, as they have been shown to do in murine systems, to determine the usefulness of α-glycosylceramides in cancer immunotherapy in humans. Here, we show that α-glycosylceramides greatly enhance the cytotoxicity of human hepatic lymphocytes obtained from cancer patients against the tumor cell lines, K562 and Colo201, in vitro. The direct effector cells of the elicited cytotoxicity were CD3−CD56+ NK cells. Even though Vα24 TCR+NKT cells proliferated remarkably in response to α-glycosylceramides, they did not contribute directly to the cytotoxicity. Our observations strongly suggest the potential usefulness of α-glycosylceramides for immunotherapy of liver cancer in humans based on their ability to activate CD3−CD56+ NK cells in the liver.
Genetic Control of Glycoprotein 70 Autoantigen Production and Its Influence on Immune Complex Levels and Nephritis in Murine Lupus
Authors: Tucker Rebecca M. , Vyse Timothy J. , Rozzo Stephen , Roark Christina L. , Izui Shozo , Kotzin Brian L.
Published: April 2014

The F1 hybrids of New Zealand Black (NZB) and New Zealand White (NZW) mice spontaneously develop an autoimmune disease that serves as a model for human systemic lupus erythematosus. Autoimmunity in (NZB × NZW)F1 mice includes the production of autoantibodies to the endogenous retroviral envelope glycoprotein, gp70, and gp70-anti-gp70 immune complexes (gp70 IC) have been implicated in the development of lupus nephritis in these animals. We used backcross and intercross combinations of C57BL/6 (B6; low gp70 levels) and NZB mice (high gp70 levels) to examine the contribution of serum gp70 Ag levels to the development of gp70 IC and nephritis. Analysis of (B6.H2z × NZB)F1 × NZB backcross mice and (NZB × B6)F2 mice showed a much stronger association of gp70 IC with kidney disease compared with IgG anti-chromatin autoantibodies in both populations of mice. Serum levels of gp70 correlated with production of gp70 IC in mice producing autoantibodies, although the overall effect on nephritis appeared to be small. Genetic mapping revealed three NZB-derived regions on chromosomes 2, 4, and 13 that were strongly linked with increased gp70 levels, and together, accounted for over 80% of the variance for this trait. However, additional linkage analyses of these crosses showed that loci controlling autoantibody production rather than gp70 levels were most important in the development of nephritogenic immune complexes. Together, these studies characterize a set of lupus-susceptibility loci distinct from those that control autoantibody production and provide new insight into the components involved in the strong association of gp70 IC with murine lupus nephritis.
Dynamics of HIV-Specific CD8+ T Lymphocytes with Changes in Viral Load
Authors: Mollet Lucile , Li Tai-Sheng , Samri Assia , Tournay Claire , Tubiana Roland , Calvez Vincent , Debré Patrice , Katlama Christine , Autran Brigitte ,   the RESTIM and COMET Study Groups
Published: April 2014

The influence of HIV burden variations on the frequencies of Ag-specific CD8+ T cell responses was evaluated before and during highly active antiretroviral therapy by analyzing the number, diversity, and function of these cells. The frequencies of HLA-A2-restricted CD8+ PBL binding HLA-A2/HIV-epitope tetramers or producing IFN-γ were below 1%. A panel of 16 CTL epitopes covering 15 HLA class I molecules in 14 patients allowed us to test 3.8 epitopes/patient and to detect 2.2 ± 1.8 HIV epitope-specific CD8+ subsets per patient with a median frequency of 0.24% (0.11–4.79%). During the first month of treatment, viral load rapidly decreased and frequencies of HIV-specific CD8 PBL tripled, eight new HIV specificities appeared of 11 undetectable at entry, while CMV-specific CD8+ PBL also appeared. With efficient HIV load control, all HIV specificities decayed involving a reduction of the CD8+CD27+CD11ahigh HIV-specific effector subset. Virus rebounds triggered by scheduled drug interruptions or transient therapeutic failures induced four patterns of epitope-specific CD8+ lymphocyte dynamics, i.e., peaks or disappearance of preexisting specificities, emergence of new specificities, or lack of changes. The HIV load rebounds mobilized both effector/memory HIV- and CMV-specific CD8+ lymphocytes. Therefore, frequencies of virus-specific CD8 T cells appear to be positively correlated to HIV production in most cases during highly active antiretroviral therapy, but an inverse correlation can also be observed with rapid virus changes that might involve redistribution, sequestration, or expansion of these Ag-specific CD8 T cells. Future strategies of therapeutic interruptions should take into account these various HIV-specific cell dynamics during HIV rebounds.
Fusions of Human Ovarian Carcinoma Cells with Autologous or Allogeneic Dendritic Cells Induce Antitumor Immunity
Authors: Gong Jianlin , Nikrui Najmosama , Chen Dongshu , Koido Shigeo , Wu Zekui , Tanaka Yasuhiro , Cannistra Stephen , Avigan David , Kufe Donald
Published: April 2014

Human ovarian carcinomas express the CA-125, HER2/neu, and MUC1 tumor-associated Ags as potential targets for the induction of active specific immunotherapy. In the present studies, human ovarian cancer cells were fused to human dendritic cells (DC) as an alternative strategy to induce immunity against known and unidentified tumor Ags. Fusions of ovarian cancer cells to autologous DC resulted in the formation of heterokaryons that express the CA-125 Ag and DC-derived costimulatory and adhesion molecules. Similar findings were obtained with ovarian cancer cells fused to allogeneic DC. The fusion cells were functional in stimulating the proliferation of autologous T cells. The results also demonstrate that fusions of ovarian cancer cells to autologous or allogeneic DC induce cytolytic T cell activity and lysis of autologous tumor cells by a MHC class I-restricted mechanism. These findings demonstrate that fusions of ovarian carcinoma cells and DC activate T cell responses against autologous tumor and that the fusions are functional when generated with either autologous or allogeneic DC.