bluuebunny/crossref_metadata_2025 huggingface dataset:
Zap70 Signaling Pathway Mediates Glucocorticoid Receptor-Dependent Transcriptional Activation: Role in the Regulation of Annexin 1 Expression in T Cells
Authors: Ishaq Mohammad , DeGray Gerald , Mou Kathy , Aguilera Angelica , Yang Jun , Lempicki Richard A. , Hazen Allison , Natarajan Ven
Published: April 2014

We have recently shown that Zap70 is important in retinoid receptor-dependent transactivation in T lymphocytes. We report that Zap70 signaling is also essential in dexamethasone-inducible glucocorticoid receptor (GR)-mediated transactivation in T lymphocytes. Zap70-negative Jurkat T cells and cells reconstituted with inactive Zap70 exhibited attenuated GR-mediated activation as compared with Zap70 reconstituted and wild-type cells. Lck-lacking Jurkat cells were also found to show markedly reduced GR activation, and reconstitution with Lck restored the activation. Gene array and protein analysis showed that the level of annexin 1 (ANXA1), an anti-inflammatory protein known to be induced and released by the glucocorticoid action, was significantly reduced in Zap70-negative and Zap70-inactive Jurkat cells as compared with wild-type cells. Lck-lacking cells were also found to have markedly reduced ANXA1 levels and reconstitution with Lck restored the ANXA1 expression. RNA interference-induced knockdown of Zap70 or Lck in Jurkat cells and peripheral blood T lymphocytes also resulted in the loss of ANXA1 expression. Transcriptional analysis revealed that dexamethasone-inducible GR-mediated activation of ANXA1 promoter was compromised in both Zap70 knocked down peripheral blood T cells and Zap70 or Lck-deficient/Lck-inactive Jurkat cells, indicating an essential role of these kinases in GR-mediated ANXA1 promoter activation in T lymphocytes. To summarize, our data demonstrate an important role for Zap70 signaling in GR-mediated transactivation in T lymphocytes and also point out a crucial role of this kinase in maintaining normal ANXA1 levels in these cells.
Identification of a Second Group of Type I IFNs in Fish Sheds Light on IFN Evolution in Vertebrates
Authors: Zou Jun , Tafalla Carolina , Truckle Jonathan , Secombes Chris J.
Published: April 2014

In this report, three type I IFN genes were identified in rainbow trout (rt) Oncorhynchus mykiss and are classified into two groups based on their primary protein sequences: group I containing two cysteine residues; and group II containing four cysteines residues. The group I rtIFNs were induced in fibroblasts (RTG-2 cells), macrophages (RTS-11 cells), and head kidney leukocytes when stimulated with polyinosinic:polycytidylic acid, whereas group II IFN was up-regulated in head kidney leukocytes but not in RTG-2 and RTS-11 cells. Recombinant group I rtIFNs were potent at inducing Mx expression and eliciting antiviral responses, whereas recombinant group II rtIFN was poor in these activities. That two subgroups of type I IFN exist in trout prompted a survey of the genomes of several fish species, including zebrafish, medaka, threespine stickleback and fugu, the amphibian Xenopus tropicalis, the monotreme platypus and the marsupial opossum, to gain further insight into possible IFN evolution. Analysis of the sequences confirmed that the new IFN subgroup found in trout (group II IFN) exists in other fish species but was not universally present in fish. The IFN genes in amphibians were shown for the first time to contain introns and to conserve the four cysteine structure found in all type I IFNs except IFN-βε and fish group I IFN. The data overall support the concept that different vertebrate groups have independently expanded their IFN types, with deletion of different pairs of cysteines apparent in fish group I IFN and IFN-βε of mammals.
IFN-γ and R-848 Dependent Activation of Human Monocyte-Derived Dendritic Cells by Neisseria meningitidis Adhesin A
Authors: Mazzon Cristina , Baldani-Guerra Barbara , Cecchini Paola , Kasic Tihana , Viola Antonella , de Bernard Marina , Aricò Beatrice , Gerosa Franca , Papini Emanuele
Published: April 2014

A soluble recombinant form of Neisseria meningitidis adhesin A (NadAΔ351–405), proposed as a constituent of anti-meningococcal B vaccines, is here shown to specifically interact with and immune-modulate human monocyte-derived dendritic cells (mo-DCs). After priming with IFN-γ and stimulation with NadAΔ351–405, mo-DCs strongly up-regulated maturation markers CD83, CD86, CD80, and HLA-DR, secreted moderate quantities of TNF-α, IL-6, and IL-8, and produced a slight, although significant, amount of IL-12p70. Costimulation of mo-DCs with NadAΔ351–405 and the imidoazoquinoline drug R-848, believed to mimic bacterial RNA, increased CD86 in an additive way, but strongly synergized the secretion of IL-12p70, IL-1, IL-6, TNF-α, and MIP-1α, especially after IFN-γ priming. CD86/CD80 overexpression correlated with the occupation of high-(kd ∼ 80 nM) and low-(kd ∼ 4 μM) affinity binding sites for NadAΔ351–405. Alternatively, secretion of IL-12p70 and TNF-α, IL-6, and IL-8 corresponded to the occupation of high- or low-affinity receptors, respectively. Mo-DCs matured by IFN-γ and NadAΔ351–405 supported the proliferation of naive CD4+ T lymphocytes, inducing the differentiation of both IFN-γ and IL-4 producing phenotypes. Our data show that NadA not only is a good immunogen but is as well endowed with a proimmune, self-adjuvating, activity.
Function and Regulation of SPLUNC1 Protein in Mycoplasma Infection and Allergic Inflammation
Authors: Chu Hong Wei , Thaikoottathil Jyoti , Rino John G. , Zhang Gongyi , Wu Qun , Moss Taylor , Refaeli Yosef , Bowler Russell , Wenzel Sally E. , Chen Zhongzhou , Zdunek Jeffrey , Breed Rachel , Young Ryan , Allaire Erin , Martin Richard J.
Published: April 2014

Respiratory infections, including Mycoplasma pneumoniae (Mp), contribute to asthma pathobiology. To date, the mechanisms underlying the increased susceptibility of asthmatics to airway Mp infection remain unclear. Short palate, lung, and nasal epithelium clone 1 (SPLUNC1) protein is a recently described large airway epithelial cell-derived molecule that was predicted to exert host defense activities. However, SPLUNC1 function and regulation in an infectious or allergic milieu are still unknown. We determined host defense and anti-inflammatory functions of SPLUNC1 protein in Mp infection and the regulation of SPLUNC1 by Mp and allergic inflammation (e.g., IL-13). SPLUNC1 function was examined in Mp or human airway epithelial cell cultures by using SPLUNC1 recombinant protein, overexpression and RNA interference. Human and mouse bronchial epithelial SPLUNC1 was examined using immunostaining, Western blotting, ELISA, laser capture microdissection, and real-time PCR. Mouse models of Mp infection and allergic inflammation and air-liquid interface cultures of normal human primary bronchial epithelial cells were used to study SPLUNC1 regulation by Mp and IL-13. We found that: 1) SPLUNC1 protein decreased Mp levels and inhibited epithelial IL-8 production induced by Mp-derived lipoproteins; 2) normal human and mouse large airway epithelial cells expressed high levels of SPLUNC1; and 3) although Mp infection increased SPLUNC1, IL-13 significantly decreased SPLUNC1 expression and Mp clearance. Our results suggest that SPLUNC1 serves as a novel host defense protein against Mp and that an allergic setting markedly reduces SPLUNC1 expression, which may in part contribute to the persistent nature of bacterial infections in allergic airways.
Pathogenic Complement Activation in Collagen Antibody- Induced Arthritis in Mice Requires Amplification by the Alternative Pathway
Authors: Banda Nirmal K. , Takahashi Kazue , Wood Allyson K. , Holers V. Michael , Arend William P.
Published: April 2014

Immune complex-induced inflammation can be mediated by the classical pathway of complement. However, using mice genetically deficient in factor B or C4, we have shown that the collagen Ab-induced model of arthritis requires the alternative pathway of complement and is not dependent on the classical pathway. We now demonstrate that collagen Ab-induced arthritis is not altered in mice genetically deficient in either C1q or mannose-binding lectins A and C, or in both C1q and mannose-binding lectins. These in vivo results prove the ability of the alternative pathway to carry out pathologic complement activation in the combined absence of intact classical and lectin pathways. C3 activation was also examined in vitro by adherent collagen-anti-collagen immune complexes using sera from normal or complement-deficient mice. These results confirm the ability of the alternative pathway to mediate immune complex-induced C3 activation when C4 or C1q, or both C1q and mannose-binding lectins, are absent. However, when all three activation pathways of complement are intact, initiation by immune complexes occurs primarily by the classical pathway. These results indicate that the alternative pathway amplification loop, with its ability to greatly enhance C3 activation, is necessary to mediate inflammatory arthritis induced by adherent immune complexes.
Variant IL-1 Receptor-Associated Kinase-1 Mediates Increased NF-κB Activity
Authors: Liu Gang , Tsuruta Yuko , Gao Zhiqian , Park Young-Jun , Abraham Edward
Published: April 2014

IL-1R-associated kinase (IRAK)-1 is a critical mediator of TLR/IL-1R-induced activation of the transcription factor NF-κB. We previously described that a commonly occurring IRAK-1 variant haplotype, containing amino acid changes from serine to phenylalanine at position 196 and from leucine to serine at position 532, is associated with increased activation of NF-κB in LPS-stimulated neutrophils from patients with sepsis-induced acute lung injury and also higher mortality and more severe clinical outcomes in such patients. To investigate the underlying molecular mechanisms, we examined the ability of wild-type and variant IRAK-1 to modulate NF-κB activation. We found increased NF-κB transcriptional activity and expression of NF-κB-dependent proinflammatory cytokines in IL-1β-stimulated IRAK-1-deficient cells transfected with variant IRAK-1 as compared with IRAK-1 wild type. IκB-α degradation was faster and p65 phosphorylation more prolonged after IL-1β stimulation in cells expressing the IRAK-1 variant. However, IL-1-induced activation of MAPKs and nuclear translocation of NF-κB are comparable in both IRAK-1 variant- and IRAK-1 wild-type-expressing cells. Autophosphorylation of the IRAK-1 variant is greater than that found with wild-type IRAK-1. Additionally, variant IRAK-1 has greater interaction with TNFR-associated factor 6 than does wild-type IRAK-1. The enhanced activity of variant IRAK-1 appeared to be due to the alteration at aa 532, with only minimal effects being associated with change at aa 196. These results demonstrate that variant IRAK-1 is associated with alterations in multiple intracellular events that are likely to contribute to increased NF-κB activation and inflammatory responses in individuals with this IRAK-1 haplotype.
Herpesvirus Chemokine-Binding Glycoprotein G (gG) Efficiently Inhibits Neutrophil Chemotaxis In Vitro and In Vivo
Authors: Van de Walle Gerlinde R. , May Maeva L. , Sukhumavasi Woraporn , von Einem Jens , Osterrieder Nikolaus
Published: April 2014

Glycoprotein G (gG) of alphaherpesviruses has been described to function as a viral chemokine-binding protein (vCKBP). More recently, mutant viruses devoid of gG have been shown to result in increased virulence, but it remained unclear whether the potential of gG to serve as a vCKBP is responsible for this observation. In this study, we used equine herpesvirus type 1 (EHV-1) as a model to study the pathophysiological importance of vCKBP activity. First, in vitro chemotaxis assays studying migration of immune cells, an important function of chemokines, were established. In such assays, supernatants of EHV-1-infected cells significantly inhibited IL-8-induced chemotaxis of equine neutrophils. Identification of gG as the responsible vCKBP was achieved by repeating similar experiments with supernatants from cells infected with a gG-negative mutant, which were unable to alter IL-8-induced equine neutrophil migration. Furthermore, rEHV-1 gG was able to significantly reduce neutrophil migration, establishing gG as a bona fide vCKBP. Second, and importantly, in vivo analyses in a murine model of EHV-1 infection showed that neutrophil migration in the target organ lung was significantly reduced in the presence of gG. In summary, we demonstrate for the first time that EHV-1 gG not only binds to chemokines but is also capable of inhibiting their chemotactic function both in vitro and in vivo, thereby contributing to viral pathogenesis and virulence.
A Soluble Form of Lymphocyte Activation Gene-3 (IMP321) Induces Activation of a Large Range of Human Effector Cytotoxic Cells
Authors: Brignone Chrystelle , Grygar Caroline , Marcu Manon , Schäkel Knut , Triebel Frédéric
Published: April 2014

The principal antitumor immune response is mediated through the activation of type 1 cytotoxic (Tc1) CD8 T cells, NK cells, and monocytes/macrophages. In this study, we investigated the potency of a clinical-grade soluble form of lymphocyte activation gene-3 protein (IMP321), a physiological high-affinity MHC class II binder, at inducing in PBMCs an appropriate cytotoxic-type response in short-term ex vivo assays. We found that IMP321 binds to a minority (<10%) of MHC class II + cells in PBMCs, including all myeloid dendritic cells, and a small fraction of monocytes. Four hours after addition of IMP321 to PBMCs, these myeloid cells produce TNF-α and CCL4 as determined by intracellular staining. At 18 h, 1% of CD8+ T cells and 3.7% NK cells produce Tc1 cytokines such as IFN-γ and/or TNF-α (mean values from 60 blood donors). Similar induction was observed in metastatic cancer patient PBMCs, but the values were lower for the NK cell subset. Early APC activation by IMP321 is needed for this Tc1-type activation because pure sorted CD8+ T cells could not be activated by IMP321. Only Ag-experienced, fully differentiated granzyme+ CD8 T cells (effector and effector memory but not naive or central memory T cells) are induced by IMP321 to full Tc1 activation. In contrast to IMP321, TLR1-9 agonists induce IL-10 and are therefore unable to induce this Tc1 IFN-γ+ response. Thus, IMP321 has many properties that confirm its potential to be a new class of immunopotentiator in cancer patients.
Cutting Edge: Lack of Evidence for Connexin-43 Expression in Human Epidermal Langerhans Cells
Authors: Zimmerli Simone C. , Masson Florence , Cancela José , Meda Paolo , Hauser Conrad
Published: April 2014

A provocative study has shown that viral peptides may be transferred in vitro from epithelial cells to APC through connexin-43 gap junction channels. In support of this cross-presentation pathway, the study also reported that human dendritic cells, including Langerhans cells of skin, express connexin-43. In this report we show that if this was the case, the levels of connexin-43 are below those detectable by immunofluorescence, flow cytometry, quantitative PCR of purified CD1a+ cells, and electron microscopy, raising questions about the relevance of the connexin-43-dependent mechanism for Langerhans cells of noninflamed human skin.
Ambient Ozone Primes Pulmonary Innate Immunity in Mice
Authors: Hollingsworth John W. , Maruoka Shuichiro , Li Zhuowei , Potts Erin N. , Brass David M. , Garantziotis Stavros , Fong Alan , Foster W. Michael , Schwartz David A.
Published: April 2014

Exposure to ozone in air pollution in urban environments is associated with increases in pulmonary-related hospitalizations and mortality. Because ozone also alters clearance of pulmonary bacterial pathogens, we hypothesized that inhalation of ozone modifies innate immunity in the lung. To address our hypothesis, we exposed C57BL/6J mice to either free air or ozone, and then subsequently challenged with an aerosol of Escherichia coli LPS. Pre-exposure to ozone resulted in enhanced airway hyperreactivity, higher concentrations of both total protein and proinflammatory cytokines in lung lavage fluid, enhanced LPS-mediated signaling in lung tissue, and higher concentrations of serum IL-6 following inhalation of LPS. However, pre-exposure to ozone dramatically reduced inflammatory cell accumulation to the lower airways in response to inhaled LPS. The reduced concentration of cells in the lower airways was associated with enhanced apoptosis of both lung macrophages and systemic circulating monocytes. Moreover, both flow cytometry and confocal microscopy indicate that inhaled ozone causes altered distribution of TLR4 on alveolar macrophages and enhanced functional response to endotoxin by macrophages. These observations indicate that ozone exposure increases both the pulmonary and the systemic biologic response to inhaled LPS by priming the innate immune system.
Serine Protease Inhibitor 6-Deficient Mice Have Increased Neutrophil Immunity to Pseudomonas aeruginosa
Authors: Zhang Manling , Liu Ni , Park Sun-Mi , Wang Yue , Byrne Susan , Murmann Andrea E. , Bahr Scott , Peter Marcus E. , Olson Steven T. , Belaaouaj Abderrazzaq , Ashton-Rickardt Philip G.
Published: April 2014

Inflammation is a localized, protective response to trauma or microbial invasion that destroys the injurious agent and the injured tissue. Neutrophil elastase (NE), a serine protease stored in the azurophil granules of polymorphonuclear neutrophils, digests microbes after phagocytosis. NE can also digest microbes extracellularly but is associated with tissue damage and inflammatory disease. In this study, we show that polymorphonuclear neutrophils from mice deficient in serine protease inhibitor 6, a weak intracellular NE inhibitor, had increased susceptibility to self-inflicted lysis because of increased NE activity. The resulting transient increase in local extracellular NE activity was within a narrow range that resulted in the clearance of Pseudomonas aeruginosa but did not damage the lung. Therefore, deficiency in a weak intracellular inhibitor of NE results in an acute inflammatory response that protects from P. aeruginosa but does not cause lung disease.
TLR4 on Follicular Dendritic Cells: An Activation Pathway That Promotes Accessory Activity
Authors: El Shikh Mohey Eldin M. , El Sayed Rania M. , Wu Yongzhong , Szakal Andras K. , Tew John G.
Published: April 2014

Microbial molecular patterns engage TLRs and activate dendritic cells and other accessory cells. Follicular dendritic cells (FDCs) exist in resting and activated states, but are activated in germinal centers, where they provide accessory function. We reasoned that FDCs might express TLRs and that engagement might activate FDCs by up-regulating molecules important for accessory activity. To test this hypothesis, TLR4 expression on FDCs was studied in situ with immunohistochemistry, followed by flow cytometry and RT-PCR analysis. TLR4 was expressed on FDC reticula in situ, and flow cytometry indicated that TLR4 was expressed on surface membranes and TLR4 message was readily apparent in FDCs by RT-PCR. Injecting mice or treating purified FDCs with LPS up-regulated molecules important for accessory activity including, FDC-FcγRIIB, FDC-ICAM-1, and FDC-VCAM-1. Treatment of purified FDCs with LPS also induced intracellular phospho-IκB-α, indicating NF-κB activation, and that correlated with increased FcγRIIB, ICAM-1, and VCAM-1. FDCs in C3H/HeJ mice were not activated with LPS even when mice were reconstituted with C3H/HeN leukocytes, suggesting that engagement of FDC-TLR4 is necessary for activation. Moreover, activated FDCs exhibited increased accessory activity in anti-OVA recall responses in vitro, and the FDC number could be reduced 4-fold if they were activated. In short, we report expression of TLR4 on FDCs for the first time and that engagement of FDC-TLR4 activated NF-κB, up-regulated expression of molecules important in FDC accessory function, including FcγRIIB, ICAM-1, and VCAM-1, as well as FDC accessory activity in promoting recall IgG responses.
B Cell Antigen Receptor-Induced Rac1 Activation and Rac1-Dependent Spreading Are Impaired in Transitional Immature B Cells Due to Levels of Membrane Cholesterol
Authors: Brezski Randall J. , Monroe John G.
Published: April 2014

The BCR-triggered responses of mature and transitional immature B cells differ at both the biochemical and functional level. In this study, we show that in mature B cells, BCR signaling triggers Vav phosphorylation and Rac1 activation. Furthermore, we demonstrate that although downstream actin-dependent BCR capping is independent of Rac1 activation, actin-dependent membrane ruffling and cell spreading are Rac1-dependent processes. In contrast, BCR-induced Vav phosphorylation and Rac1 activation is impaired in transitional immature B cells, resulting in defects in actin polymerization-dependent spreading and membrane ruffling while Rac1-independent BCR capping remains intact. Because transitional immature murine B cells maintain lower steady-state levels of plasma membrane cholesterol, we augmented their levels to that of mature B cells and found that BCR-induced Rac1 activation and Rac1-dependent membrane ruffling and cell spreading were restored. These studies provide a direct link between B cell cholesterol levels and downstream cellular signaling processes.
Negative Regulation of CD40-Mediated B Cell Responses by E3 Ubiquitin Ligase Casitas-B-Lineage Lymphoma Protein-B
Authors: Qiao Guilin , Lei Minxiang , Li Zhenping , Sun Yonglian , Minto Andrew , Fu Yang-Xin , Ying Haiyan , Quigg Richard J. , Zhang Jian
Published: April 2014

It has been documented that CD40 is essential for B cell function. Casitas-B-lineage lymphoma protein-b (Cbl-b), an adapter protein and ubiquitin ligase, has been shown to regulate the activation of T and B cells through their Ag receptors. In this study, we report that CD40-induced B cell proliferation is significantly augmented in mice lacking Cbl-b. Furthermore, Cbl-b−/− mice display enhanced thymus-dependent Ab responses and germinal center formation, whereas introduction of CD40 deficiency abolishes these effects. Hyper thymus-dependent humoral response in Cbl-b−/− mice is in part due to an intrinsic defect in B cells. Mechanistically, Cbl-b selectively down-modulates CD40-induced activation of NF-κB and JNK. Cbl-b associates with TNF receptor-associated factor 2 upon CD40 ligation, and inhibits the recruitment of TNF receptor-associated factor 2 to the CD40. Together, our data suggest that Cbl-b attenuates CD40-mediated NF-κB and JNK activation, thereby suppressing B cell responses.
The CD16−CD56bright NK Cell Subset Is Resistant to Reactive Oxygen Species Produced by Activated Granulocytes and Has Higher Antioxidative Capacity Than the CD16+CD56dim Subset
Authors: Harlin Helena , Hanson Mikael , Johansson C. Christian , Sakurai Daiju , Poschke Isabel , Norell Håkan , Malmberg Karl-Johan , Kiessling Rolf
Published: April 2014

Human NK cells can be divided into CD56dim and CD56bright subsets. These two types of NK cells respond to different types of stimuli, with CD56dim NK cells having direct cytotoxic ability and CD56bright NK cells having mainly an immunoregulatory function. We show that the CD16+CD56dim NK subset is characterized by sensitivity to cell death induced by activated granulocytes. We identified hydrogen peroxide (H2O2) as the major effector molecule responsible for the cytotoxic effect of granulocytes on CD56dim NK cells, because the ability of granulocytes to kill CD56dim NK cells was completely abrogated in the presence of the hydrogen peroxide scavenger catalase. When exposing NK cells to H2O2, CD56dim cells showed rapid mitochondrial depolarization and down-regulation of activating NKRs, eventually resulting in cell death, whereas CD56bright cells remained unaffected. The difference in sensitivity to H2O2 was mirrored by a difference in intracellular oxidation levels between CD56dim and CD56bright NK cells, and cell lysates from the latter subset possessed a greater ability to block H2O2-mediated oxidation. Our data may explain the preferential accumulation of CD56bright NK cells often seen in environments rich in reactive oxygen species, such as at sites of chronic inflammation and in tumors.
A Novel Mechanism for TNFR-Associated Factor 6-Dependent CD40 Signaling
Authors: Rowland Sarah L. , Tremblay Mikaela M. , Ellison Jason M. , Stunz Laura L. , Bishop Gail A. , Hostager Bruce S.
Published: April 2014

Members of the TNFR family play critical roles in the regulation of the immune system. One member of the family critical for efficient activation of T-dependent humoral immune responses is CD40, a cell surface protein expressed by B cells and other APC. The cytoplasmic domain of CD40 interacts with several members of the TNFR-associated factor (TRAF) family, which link CD40 to intracellular signaling pathways. TRAF2 and 6 appear to play particularly important roles in CD40 signaling. Previous studies suggest that the two molecules have certain overlapping roles in signaling, but that unique roles for each molecule also exist. To better define the roles of TRAF2 and TRAF6 in CD40 signaling, we used somatic cell gene targeting to generate TRAF-deficient mouse B cell lines. A20.2J cells deficient in TRAF6 exhibit marked defects in CD40-mediated JNK activation and the up-regulation of CD80. Our previous experiments with TRAF2-deficient B cell lines suggest that TRAF6 and TRAF2 may have redundant roles in CD40-mediated NF-κB activation. Consistent with this hypothesis, we found CD40-mediated activation of NF-κB intact in TRAF6-deficient cells and defective in cells lacking both TRAF2 and TRAF6. Interestingly, we found that TRAF6 mutants defective in CD40 binding were able to restore CD40-mediated JNK activation and CD80 up-regulation in TRAF6-deficient cells, indicating that TRAF6 may be able to contribute to certain CD40 signals without directly binding CD40.
TLR9 Activation Induces Normal Neutrophil Responses in a Child with IRAK-4 Deficiency: Involvement of the Direct PI3K Pathway
Authors: Hoarau Cyrille , Gérard Bénédicte , Lescanne Emmanuel , Henry Dominique , François Stéphanie , Lacapère Jean-Jacques , El Benna Jamel , Dang Pham My-Chan , Grandchamp Bernard , Lebranchu Yvon , Gougerot-Pocidalo Marie-Anne , Elbim Carole
Published: April 2014

Polymorphonuclear neutrophils (PMN) play a key role in innate immunity. Their activation and survival are tightly regulated by microbial products via pattern recognition receptors such as TLRs, which mediate recruitment of the IL-1R-associated kinase (IRAK) complex. We describe a new inherited IRAK-4 deficiency in a child with recurrent pyogenic bacterial infections. Analysis of the IRAK4 gene showed compound heterozygosity with two mutations: a missense mutation in the death domain of the protein (pArg12Cys) associated in cis-with a predicted benign variant (pArg391His); and a splice site mutation in intron 7 that led to the skipping of exon 7. A nontruncated IRAK-4 protein was detected by Western blotting. The patient’s functional deficiency of IRAK-4 protein was confirmed by the absence of IRAK-1 phosphorylation after stimulation with all TLR agonists tested. The patient’s PMNs showed strongly impaired responses (L-selectin and CD11b expression, oxidative burst, cytokine production, cell survival) to TLR agonists which engage TLR1/2, TLR2/6, TLR4, and TLR7/8; in contrast, the patient’s PMN responses to CpG-DNA (TLR9) were normal, except for cytokine production. The surprisingly normal effect of CpG-DNA on PMN functions and apoptosis disappeared after pretreatment with PI3K inhibitors. Together, these results suggest the existence of an IRAK-4-independent TLR9-induced transduction pathway leading to PI3K activation. This alternative pathway may play a key role in PMN control of infections by microorganisms other than pyogenic bacteria in inherited IRAK-4 deficiency.
Aging Up-Regulates Expression of Inflammatory Mediators in Mouse Adipose Tissue
Authors: Wu Dayong , Ren Zhihong , Pae Munkyong , Guo Weimin , Cui Xuelin , Merrill Alfred H. , Meydani Simin Nikbin
Published: April 2014

Obesity is a leading risk factor for type 2 diabetes (T2D). Aging is associated with an increase in T2D incidence, which is not totally explained by the much lower prevalence of obesity in the elderly. Low-grade inflammation in adipose tissue (AT) contributes to insulin resistance and T2D. Thus, we determined whether inflammatory responses are up-regulated with age in AT. The results showed that visceral AT from old C57BL mice had significantly higher mRNA expression of the proinflammatory cytokines IL-1β, IL-6, TNF-α, and COX-2 and lower expression of anti-inflammatory PPAR-γ than those of young mice. We further showed that adipocytes (AD) and not stromal vascular cells including macrophages (Mφ) were the cells responsible for this higher inflammatory state of the aged AT, suggesting that the age-associated increase in AT inflammation is distinguished from that seen in obesity, in which Mφ are the main contributors. However, peritoneal Mφ of either age (young or old) produced more TNF-α and IL-6 after incubation in old AD-conditioned medium compared with young AD-conditioned medium. This suggests that in addition to producing more inflammatory cytokines, AD from old mice induce a higher inflammatory response in other cells. Sphingolipid ceramide was higher in old compared with young AD. Reducing ceramide levels or inhibiting NF-κB activation decreased cytokine production, whereas the addition of ceramide increased cytokine production in young AD to a level comparable to that seen in old AD, suggesting that ceramide-induced activation of NF-κB plays a key role in AT inflammation.
Synergistic Induction of Antigen-Specific CTL by Fusions of TLR-Stimulated Dendritic Cells and Heat-Stressed Tumor Cells
Authors: Koido Shigeo , Hara Eiichi , Homma Sadamu , Mitsunaga Makoto , Takahara Akitaka , Nagasaki Eijiro , Kawahara Hidejiro , Watanabe Michiaki , Toyama Yoichi , Yanagisawa Satoru , Kobayashi Susumu , Yanaga Katsuhiko , Fujise Kiyotaka , Gong Jianlin , Tajiri Hisao
Published: April 2014

Dendritic cell (DC)/tumor cell fusion cells (FCs) can induce potent CTL responses. The therapeutic efficacy of a vaccine requires the improved immunogenicity of both DCs and tumor cells. The DCs stimulated with the TLR agonist penicillin-killed Streptococcus pyogenes (OK-432; OK-DCs) showed higher expression levels of MHC class I and II, CD80, CD86, CD83, IL-12, and heat shock proteins (HSPs) than did immature DCs. Moreover, heat-treated autologous tumor cells displayed a characteristic phenotype with increased expression of HSPs, carcinoembryonic Ag (CEA), MUC1, and MHC class I (HLA-A2 and/or A24). In this study, we have created four types of FC preparation by alternating fusion cell partners: 1) immature DCs fused with unheated tumor cells; 2) immature DCs fused with heat-treated tumor cells; 3) OK-DCs fused with unheated tumor cells; and 4) OK-DCs fused with heat-treated tumor cells. Although OK-DCs fused with unheated tumor cells efficiently enhanced CTL induction, OK-DCs fused with heat-treated tumor cells were most active, as demonstrated by: 1) up-regulation of multiple HSPs, MHC class I and II, CEA, CD80, CD86, CD83, and IL-12; 2) activation of CD4+ and CD8+ T cells able to produce IFN- γ at higher levels; 3) efficient induction of CTL activity specific for CEA or MUC1 or both against autologous tumor; and 4) superior abilities to induce CD107+IFN-γ+CD8+ T cells and CD154+ IFN-γ+CD4+ T cells. These results strongly suggest that synergism between OK-DCs and heat-treated tumor cells enhances the immunogenicity of FCs and provides a promising means of inducing therapeutic antitumor immunity.
The Surprising Kinetics of the T Cell Response to Live Antigenic Cells
Authors: Tyznik Aaron J. , Bevan Michael J.
Published: April 2014

Cooperation between CD4+ and CD8+ T cells is required for the proper development of primary effector and memory CD8+ T cells following immunization with noninflammatory immunogens. In this study, we characterized murine CD4+ and CD8+ T cell responses to male-specific minor histocompatibility (HY) Ags following injection of live male cells into females of the same strain. Male cells are rejected 10–12 days after transfer, coinciding with the expansion and effector function of CD8+ CTLs to two H-2Db-restricted epitopes. Although anti-HY CD4+ T cell responses are readily detectable day 5 posttransfer, CD8+ responses are undetectable until day 10. The early CD4+ response is not dependent on direct presentation of Ag by donor male cells, but depends on presentation of the male cells by recipient APC. The CD4+ T cell response is required for the priming of CD8+ T cell effector responses and rejection of HY-incompatible cells. Unexpectedly, HY-specific CD4+ T cells are also capable of efficiently lysing target cells in vivo. The delay in the CD8+ T cell response can be largely abrogated by depleting T cells from the male inoculum, and donor male CD8+ T cells in particular suppress host anti-HY CD8+ responses. These data demonstrate dramatic differences in host T cell responses to noninflammatory Ags compared with responses to pathogens. We explain the delayed CD8+ response by proposing that there is a balance between cross-presentation of Ag by helper cell-licensed dendritic cells, on the one hand, and veto suppression by live male lymphocytes on the other.
The Countervailing Actions of Myeloid and Plasmacytoid Dendritic Cells Control Autoimmune Diabetes in the Nonobese Diabetic Mouse
Authors: Saxena Vijay , Ondr Jennifer K. , Magnusen Albert F. , Munn David H. , Katz Jonathan D.
Published: April 2014

Islet Ag-specific CD4+ T cells receive antigenic stimulation from MHC class II-expressing APCs. Herein, we delineate the direct in vivo necessity for distinct subsets of macrophages and dendritic cells (DC) in type 1 diabetes mellitus of the NOD mouse by using diphtheria toxin-mediated cell ablation. The ablation of macrophages had no impact on islet Ag presentation or on the induction of insulitis or diabetes in either transfer or spontaneous models. However, the ablation of CD11b+CD11c+ DC led to the loss of T cell activation, insulitis, and diabetes mediated by CD4+ T cells. When the specific myeloid DC subset was “added-back” to mice lacking total DC, insulitis and diabetes were restored. Interestingly, when NOD mice were allowed to progress to the insulitis phase, the ablation of DC led to accelerated insulitis. This accelerated insulitis was mediated by the loss of plasmacytoid DC (pDC). When pDC were returned to depleted mice, the localized regulation of insulitis was restored. The loss of pDC in the pancreas itself was accompanied by the localized loss of IDO and the acceleration of insulitis. Thus, CD11c+CD11b+ DC and pDC have countervailing actions in NOD diabetes, with myeloid DC providing critical antigenic stimulation to naive CD4+ T cells and pDC providing regulatory control of CD4+ T cell function in the target tissue.
The α1β1 Integrin and TNF Receptor II Protect Airway CD8+ Effector T Cells from Apoptosis during Influenza Infection
Authors: Richter Martin V. , Topham David J.
Published: April 2014

Primary viral infections of the lung induce potent effector CD8 T cell responses. To function in the influenza-infected airways, CD8 T cells must be able to resist cell death. The majority of the CD8 T cells in the airways and lung parenchyma expressed CD49a, the α-chain of the type IV collagen receptor VLA-1, and these cells were highly activated, producing both IFN-γ and TNF-α. In the airways, where type IV collagen is abundant, but not the spleen, the CD49a+ CD8 cells had reduced proportions of annexin V and caspase 8, and >80% expressed the TNF-α receptor II, while Fas, TNFR-I, and CD27 expression were similar to CD49a− cells. Furthermore, the CD49a+, but not CD49a−, CD8 T cells from the airways were resistant to active induction of apoptosis in the presence of type IV collagen and TNF-α in vitro. We propose that TNFR-II and the VLA-1 synergize to protect effector CD8 T cells in the infected airways from apoptosis during the acute infection.
Expression of CD80/86 on B Cells Is Essential for Autoreactive T Cell Activation and the Development of Arthritis
Authors: O’Neill Shannon K. , Cao Yanxia , Hamel Keith M. , Doodes Paul D. , Hutas Gabor , Finnegan Alison
Published: April 2014

Depletion of B cells in rheumatoid arthritis is therapeutically efficacious. Yet, the mechanism by which B cells participate in the inflammatory process is unclear. We previously demonstrated that Ag-specific B cells have two important functions in the development of arthritis in a murine model of rheumatoid arthritis, proteoglycan (PG)-induced arthritis (PGIA). PG-specific B cells function as autoantibody-producing cells and as APCs that activate PG-specific T cells. Moreover, the costimulatory molecule CD86 is up-regulated on PG-specific B cells in response to stimulation with PG. To address the requirement for CD80/CD86 expression on B cells in the development of PGIA, we generated mixed bone marrow chimeras in which CD80/CD86 is specifically deleted on B cells and not on other APC populations. Chimeras with a specific deficiency in CD80/CD86 expression on B cells are resistant to the induction of PGIA. The concentration of PG-specific autoantibody is similar in mice sufficient or deficient for CD80/86-expressing B cells, which indicates that resistance to PGIA is not due to the suppression of PG-specific autoantibody production. CD80/86-deficient B cells failed to effectively activate PG-specific autoreactive T cells as indicated by the failure of T cells from PG-immunized CD80/86-deficient B cell chimeras to transfer arthritis into SCID mice. In vitro secondary recall responses to PG are also dependent on CD80/86-expressing B cells. These results demonstrate that a CD80/86:CD28 costimulatory interaction between B cells and T cells is required for autoreactive T cell activation and the induction of arthritis but not for B cell autoantibody production.
Cross-Regulation between Type I and Type II NKT Cells in Regulating Tumor Immunity: A New Immunoregulatory Axis
Authors: Ambrosino Elena , Terabe Masaki , Halder Ramesh C. , Peng Judy , Takaku Shun , Miyake Sachiko , Yamamura Takashi , Kumar Vipin , Berzofsky Jay A.
Published: April 2014

Negative immunoregulation is a major barrier to successful cancer immunotherapy. The NKT cell is known to be one such regulator. In this study we explored the roles of and interaction between the classical type I NKT cell and the poorly understood type II NKT cell in the regulation of tumor immunity. Selective stimulation of type II NKT cells suppressed immunosurveillance, whereas stimulation of type I NKT cells protected against tumor growth even when responses were relatively skewed toward Th2 cytokines. When both were stimulated simultaneously, type II NKT cells appeared to suppress the activation in vitro and protective effect in vivo of type I NKT cells. In the absence of type I, suppression by type II NKT cells increased, suggesting that type I cells reduce the suppressive effect of type II NKT cells. Thus, in tumor immunity type I and type II NKT cells have opposite and counteractive roles and define a new immunoregulatory axis. Alteration of the balance between the protective type I and the suppressive type II NKT cell may be exploited for therapeutic intervention in cancer.
Regulation of Ca2+ Signaling in Mast Cells by Tyrosine-Phosphorylated and Unphosphorylated Non-T Cell Activation Linker
Authors: Dráberová Lubica , Shaik Gouse Mohiddin , Volná Petra , Heneberg Petr , Tůmová Magda , Lebduška Pavel , Korb Jan , Dráber Petr
Published: April 2014

Engagement of the FcεRI in mast cells and basophils leads to a rapid tyrosine phosphorylation of the transmembrane adaptors LAT (linker for activation of T cells) and NTAL (non-T cell activation linker, also called LAB or LAT2). NTAL regulates activation of mast cells by a mechanism, which is incompletely understood. Here we report properties of rat basophilic leukemia cells with enhanced or reduced NTAL expression. Overexpression of NTAL led to changes in cell morphology, enhanced formation of actin filaments and inhibition of the FcεRI-induced tyrosine phosphorylation of the FcεRI subunits, Syk kinase and LAT and all downstream activation events, including calcium and secretory responses. In contrast, reduced expression of NTAL had little effect on early FcεRI-induced signaling events but inhibited calcium mobilization and secretory response. Calcium response was also repressed in Ag-activated cells defective in Grb2, a major target of phosphorylated NTAL. Unexpectedly, in cells stimulated with thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+ ATPase, the amount of cellular NTAL directly correlated with the uptake of extracellular calcium even though no enhanced tyrosine phosphorylation of NTAL was observed. The combined data indicate that NTAL regulates FcεRI-mediated signaling at multiple steps and by different mechanisms. At early stages NTAL interferes with tyrosine phosphorylation of several substrates and formation of signaling assemblies, whereas at later stages it regulates the activity of store-operated calcium channels through a distinct mechanism independent of enhanced NTAL tyrosine phosphorylation.
A Link between PDL1 and T Regulatory Cells in Fetomaternal Tolerance
Authors: Habicht Antje , Dada Shirine , Jurewicz Mollie , Fife Brian T. , Yagita Hideo , Azuma Miyuki , Sayegh Mohamed H. , Guleria Indira
Published: April 2014

Acceptance of the fetus expressing allogeneic paternal Ags by the mother is a physiologic model of transplantation tolerance. Various mechanisms contribute to fetal evasion from immune attack by maternal leukocytes. We have recently demonstrated that the inhibitory costimulatory molecule PDL1 plays a critical role in fetomaternal tolerance in that PDL1 blockade or deficiency resulted in decreased allogeneic fetal survival rates. CD4+CD25+ T regulatory cells (Tregs) have also been demonstrated to play an important role in fetomaternal tolerance. Since PDL1 is expressed on Tregs, we explored the interactions between PDL1 and Tregs in vivo in a mouse model of fetomaternal tolerance. Depletion of CD25+ T cells abrogated the effect of anti-PDL1 Ab indicating that the effect of PDL1 is possibly mediated by CD25+ Tregs. Adoptive transfer of Tregs from wild-type but not PDL1-deficient mice into PDL1-deficient recipients significantly improved fetal survival. The frequency, phenotype and placental trafficking of Tregs from PDL1-deficient mice were similar to those of wild-type controls, but were defective in inhibiting alloreactive Th1 cells in vitro. This is the first report providing evidence for a link between PDL1 and T regulatory cells in mediating fetomaternal tolerance.
Lymphotoxin αβ2 (Membrane Lymphotoxin) Is Critically Important for Resistance to Leishmania major Infection in Mice
Authors: Xu Guilian , Liu Dong , Fan Yijun , Yang Xi , Korner Heinrich , Fu Yang-Xin , Uzonna Jude E.
Published: April 2014

Although the essential role of TNF-α in the control of intracellular pathogens including Leishmania major is well established, it is uncertain whether the related cytokine lymphotoxin αβ2 (LTα1β2, membrane lymphotoxin) plays any role in this process. In this study, we investigated the contribution of membrane lymphotoxin in host response to L. major infection by using LTβ-deficient (LTβ−/−) mice on the resistant C57BL/6 background. Despite mounting early immune responses comparable to those of wild-type (WT) mice, LTβ−/− mice developed chronic nonhealing cutaneous lesions due to progressive and unresolving inflammation that is accompanied by uncontrolled parasite proliferation. This chronic disease was associated with striking reduction in IL-12 and Ag-specific IFN-γ production by splenocytes from infected mice. Consistent with defective cellular immune response, infected LTβ−/− mice had significantly low Ag-specific serum IgG1 and IgG2a levels compared with WT mice. Although administration of rIL-12 to L. major-infected LTβ−/− mice caused complete resolution of chronic lesions, it only partially (but significantly) reduced parasite proliferation. In contrast, blockade of LIGHT signaling in infected LTβ−/− mice resulted in acute and progressive lesion development, massive parasite proliferation, and dissemination to the visceral organs. Although infected LTβ−/− WT bone marrow chimeric mice were more resistant than LTβ−/− mice, they still had reduced ability to control parasites and showed defective IL-12 and IFN-γ production compared with infected WT mice. These results suggest that membrane lymphotoxin plays critical role in resistance to L. major by promoting effective T cell-mediated anti-Leishmania immunity.
IL-13 Induces Disease-Promoting Type 2 Cytokines, Alternatively Activated Macrophages and Allergic Inflammation during Pulmonary Infection of Mice with Cryptococcus neoformans
Authors: Müller Uwe , Stenzel Werner , Köhler Gabriele , Werner Christoph , Polte Tobias , Hansen Gesine , Schütze Nicole , Straubinger Reinhard K. , Blessing Manfred , McKenzie Andrew N. J. , Brombacher Frank , Alber Gottfried
Published: April 2014

In the murine model of Cryptococcus neoformans infection Th1 (IL-12/IFN-γ) and Th17 (IL-23/IL-17) responses are associated with protection, whereas an IL-4-dependent Th2 response exacerbates disease. To investigate the role of the Th2 cytokine IL-13 during pulmonary infection with C. neoformans, IL-13-overexpressing transgenic (IL-13Tg+), IL-13-deficient (IL-13−/−), and wild-type (WT) mice were infected intranasally. Susceptibility to C. neoformans infection was found when IL-13 was induced in WT mice or overproduced in IL-13Tg+ mice. Infected IL-13Tg+ mice had a reduced survival time and higher pulmonary fungal load as compared with WT mice. In contrast, infected IL-13−/− mice were resistant and 89% of these mice survived the entire period of the experiment. Ag-specific production of IL-13 by susceptible WT and IL-13Tg+ mice was associated with a significant type 2 cytokine shift but only minor changes in IFN-γ production. Consistent with enhanced type 2 cytokine production, high levels of serum IgE and low ratios of serum IgG2a/IgG1 were detected in susceptible WT and IL-13Tg+ mice. Interestingly, expression of IL-13 by susceptible WT and IL-13Tg+ mice was associated with reduced IL-17 production. IL-13 was found to induce formation of alternatively activated macrophages expressing arginase-1, macrophage mannose receptor (CD206), and YM1. In addition, IL-13 production led to lung eosinophilia, goblet cell metaplasia and elevated mucus production, and enhanced airway hyperreactivity. This indicates that IL-13 contributes to fatal allergic inflammation during C. neoformans infection.