bluuebunny/crossref_metadata_2025 huggingface dataset:
Immature CD4−CD103+ Rat Dendritic Cells Induce Rapid Caspase-Independent Apoptosis-Like Cell Death in Various Tumor and Nontumor Cells and Phagocytose Their Victims
Authors: Trinité Benjamin , Chauvin Camille , Pêche Hélène , Voisine Cécile , Heslan Michèle , Josien Régis
Published: April 2014

We previously reported the characterization of a MHC class IIlowCD4−CD103+ (CD4−) subset of dendritic cells (DC) in rat spleen that exhibit a Ca2+-, Fas ligand-, TRAIL- and TNF-α-independent cytotoxic activity against specific targets in vitro. In this study, we demonstrate that this DC subset was also found in lymph nodes. Freshly extracted and, therefore, immature CD4− DC exhibited a potent cytotoxic activity against a large panel of tumor cell lines as well as primary endothelial cells. The cytotoxic activity of immature CD4− DC required cell-to-cell contact and de novo protein expression. CD4− DC-mediated cell death resembled apoptosis, as evidenced by outer membrane phosphatidylserine exposure and nuclear fragmentation in target cells, but was caspase as well as Fas-associated death domain and receptor-interacting protein independent. Bcl-2 overexpression in target cells did not protect them against DC-mediated cell death. Immature CD4− DC phagocytosed efficiently apoptotic cells in vitro and, therefore, rapidly and specifically engulfed their victims following death induction. Maturation induced a dramatic down-regulation of the killing and phagocytic activities of CD4− DC. In contrast, CD4+ DC were both unable to kill target cells and to phagocytose apoptotic cells in vitro. Taken together, these data indicate that rat immature CD4−CD103+ DC mediate an unusual cytotoxic activity and can use this function to efficiently acquire Ag from live cells.
Characterization of a C3a Receptor in Rainbow Trout and Xenopus: The First Identification of C3a Receptors in Nonmammalian Species
Authors: Boshra Hani , Wang Tiehui , Hove-Madsen Leif , Hansen John , Li Jun , Matlapudi Anjun , Secombes Christopher J. , Tort Lluis , Sunyer J. Oriol
Published: April 2014

Virtually nothing is known about the structure, function, and evolutionary origins of the C3aR in nonmammalian species. Because C3aR and C5aR are thought to have arisen from the same common ancestor, the recent characterization of a C5aR in teleost fish implied the presence of a C3aR in this animal group. In this study we report the cloning of a trout cDNA encoding a 364-aa molecule (TC3aR) that shows a high degree of sequence homology and a strong phylogenetic relationship with mammalian C3aRs. Northern blotting demonstrated that TC3aR was expressed primarily in blood leukocytes. Flow cytometric analysis and immunofluorescence microscopy showed that Abs raised against TC3aR stained to a high degree all blood B lymphocytes and, to a lesser extent, all granulocytes. More importantly, these Abs inhibited trout C3a-mediated intracellular calcium mobilization in trout leukocytes. A fascinating structural feature of TC3aR is the lack of a significant portion of the second extracellular loop (ECL2). In all C3aR molecules characterized to date, the ECL2 is exceptionally large when compared with the same region of C5aR. However, the exact function of the extra portion of ECL2 is unknown. The lack of this segment in TC3aR suggests that the extra piece of ECL2 was not necessary for the interaction of the ancestral C3aR with its ligand. Our findings represent the first C3aR characterized in nonmammalian species and support the hypothesis that if C3aR and C5aR diverged from a common ancestor, this event occurred before the emergence of teleost fish.
HLA-B27 Misfolding in Transgenic Rats Is Associated with Activation of the Unfolded Protein Response
Authors: Turner Matthew J. , Sowders Dawn P. , DeLay Monica L. , Mohapatra Rajashree , Bai Shuzhen , Smith Judith A. , Brandewie Jaclyn R. , Taurog Joel D. , Colbert Robert A.
Published: April 2014

The mechanism by which the MHC class I allele, HLA-B27, contributes to spondyloarthritis pathogenesis is unknown. In contrast to other alleles that have been examined, HLA-B27 has a tendency to form high m.w. disulfide-linked H chain complexes in the endoplasmic reticulum (ER), bind the ER chaperone BiP/Grp78, and undergo ER-associated degradation. These aberrant characteristics have provided biochemical evidence that HLA-B27 is prone to misfold. Recently, similar biochemical characteristics of HLA-B27 were reported in cells from HLA-B27/human β2-microglobulin transgenic (HLA-B27 transgenic) rats, an animal model of spondyloarthritis, and correlated with disease susceptibility. In this study, we demonstrate that the unfolded protein response (UPR) is activated in macrophages derived from the bone marrow of HLA-B27 transgenic rats with inflammatory disease. Microarray analysis of these cells also reveals an IFN response signature. In contrast, macrophages derived from premorbid rats do not exhibit a strong UPR or evidence of IFN exposure. Activation of macrophages from premorbid HLA-B27 transgenic rats with IFN-γ increases HLA-B27 expression and leads to UPR induction, while no UPR is seen in cells from nondisease-prone HLA-B7 transgenic or wild-type (nontransgenic) animals. This is the first demonstration, to our knowledge, that HLA-B27 misfolding is associated with ER stress that results in activation of the UPR. These observations link HLA-B27 expression with biological effects that are independent of immunological recognition, but nevertheless may play an important role in the pathogenesis of inflammatory diseases associated with this MHC class I allele.
Recombinant CD200 Protein Does Not Bind Activating Proteins Closely Related to CD200 Receptor
Authors: Hatherley Deborah , Cherwinski Holly M. , Moshref Mehrdad , Barclay A. Neil
Published: April 2014

CD200 (OX2) is a cell surface glycoprotein that interacts with a structurally related receptor (CD200R) expressed mainly on myeloid cells and is involved in regulation of macrophage and mast cell function. In mouse there are up to five genes related to CD200R with conflicting data as to whether they bind CD200. We show that mouse CD200 binds the inhibitory receptor CD200R with a comparable affinity (Kd = 4 μM) to those found for the rat and human CD200 CD200R interactions. CD200 gave negligible binding to the activating receptors, CD200RLa, CD200RLb, and CD200RLc, by direct analysis at the protein level using recombinant monomeric and dimeric fusion proteins or to CD200RLa and CD200RLb when expressed at the cell surface. An additional potential activating gene, CD200RLe, found in only some mouse strains also did not bind CD200. Thus, the CD200 receptor family consists of both activatory and inhibitory members like several other paired ligand receptors, such as signal regulatory protein, killer cell Ig-like receptor/KAR, LY49, dendritic cell immunoreceptor/dendritic cell immunoactivating receptor, and paired Ig-like type 2 receptor. Although the ligand for the inhibitory product is a widely distributed host protein, the ligands of the activating forms remain to be identified, and one possibility is that they are pathogen components.
Two Major Interacting Chromosome Loci Control Disease Susceptibility in Murine Model of Spondyloarthropathy
Authors: Végvári Anikó , Szabó Zoltán , Szántó Sándor , Nesterovitch Andrew B. , Mikecz Katalin , Glant Tibor T. , Adarichev Vyacheslav A.
Published: April 2014

Autoimmune spondylitis was induced in BALB/c mice and their MHC-matched (BALB/c × DBA/2)F1 and F2 hybrids by systemic immunization with cartilage/intervertebral disk proteoglycan (PG). As in human ankylosing spondylitis, the MHC was the major permissive genetic locus in murine PG-induced spondylitis (PGIS). Two major non-MHC chromosome loci with highly significant linkage were found on chromosomes 2 (Pgis2) and 18 (Pgis1) accounting for 40% of the entire F2 trait variance. The dominant spondylitis-susceptibility allele for Pgis2 locus is derived from the BALB/c strain, whereas the Pgis1 recessive allele was present in the disease-resistant DBA/2 strain. The Pgis1 locus significantly affected the disease-controlling Pgis2 locus, inducing as high incidence of spondylitis in F2 hybrids as was found in the spondylitis-susceptible parent BALB/c strain. Additional disease-controlling loci with suggestive linkage were mapped to the chromosomes 12, 15, and 19. Severity of spondylitis in F2 mice positively correlated with serum levels of amyloid A, IL-6, and Pg-specific Abs, and showed negative correlation with Ag-induced T cell proliferation, IFN-γ, IL-4, and TNF-α production. A major locus controlling serum IL-6 was found on chromosome 14 near osteoclast differentiation factor Tnfsf11. Locus on chromosome 11 near the Stat3 and Stat5 genes controlled serum level of the Ig IgG2a isotype. The two major genetic loci Pgis1 and Pgis2 of murine spondylitis were homologous to chromosome regions in human genome, which control ankylosing spondylitis in human patients. Thus, this animal model of experimentally induced spondylitis might facilitate the identification of spondylitis-susceptibility genes in humans.
Identification and Bioactivities of IFN-γ in Rainbow Trout Oncorhynchus mykiss: The First Th1-Type Cytokine Characterized Functionally in Fish
Authors: Zou Jun , Carrington Allison , Collet Bertrand , Dijkstra Johannes Martinus , Yoshiura Yasutoshi , Bols Niels , Secombes Chris
Published: April 2014

IFN-γ is one of the key cytokines in defining Th1 immune responses. In this study, an IFN-γ homologue has been identified in rainbow trout Oncorhynchus mykiss, and its biological activities have been characterized. The trout IFN-γ cDNA is 1034 bp in length and translates into a 180-aa protein. The first intron of the trout IFN-γ gene contains highly polymorphic GACA minisatellites and 44-bp DNA repeats, giving rise to at least six alleles. IFN-γ is structurally conserved among vertebrates, and a signature motif has been identified. A nuclear localization sequence known to be crucial for IFN-γ biological activities is also present in the C-terminal region of the trout IFN-γ. The IFN-γ expression was induced in head kidney leukocytes by stimulation with PHA or poly(I:C) and in kidney and spleen of fish injected with poly(I:C). rIFN-γ produced in Escherichia coli significantly stimulated gene expression of IFN-γ-inducible protein 10 (γIP-10), MHC class II β-chain, and STAT1, and enhanced respiratory burst activity in macrophages. Deletion of 29-aa residues from the C terminus containing the nuclear localization sequence motif resulted in loss of activity with respect to induction of γIP-10 in RTS-11 cells. Moreover, IFN-γ-induced γIP-10 expression was completely abolished by the protein kinase C inhibitor staurosporine, and partially reduced by U0126, a specific inhibitor for ERKs. Taken together, the present study has demonstrated for the first time a functional IFN-γ homologue in a fish species, strongly suggesting a conserved Th1 immune response is most likely present in lower vertebrates.
Plasmodium yoelii Can Ablate Vaccine-Induced Long-Term Protection in Mice
Authors: Wykes Michelle N. , Zhou Yong-Hong , Liu Xue Q. , Good Michael F.
Published: April 2014

Malaria is a serious cause of morbidity and mortality for people living in endemic areas, but unlike many other infections, individuals exposed to the parasite do not rapidly become resistant to subsequent infections. High titers of Ab against the 19-kDa C-terminal fragment of the merozoite surface protein-1 can mediate complete protection in model systems; however, previous studies had not determined whether this vaccine generated long-term protection. In this study, we report that functional memory cells generated by merozoite surface protein-1, per se, do not offer any protection. This is because the parasite induces deletion of vaccine-specific memory B cells as well as long-lived plasma cells including those specific for bystander immune responses. Our study demonstrates a novel mechanism by which Plasmodium ablates immunological memory of vaccines, which would leave the host immuno-compromised.
A Soluble Factor Secreted by an HIV-1-Resistant Cell Line Blocks Transcription through Inactivating the DNA-Binding Capacity of the NF-κB p65/p50 Dimer
Authors: Lesner Adam , Li Yuchang , Nitkiewicz Jadwiga , Li Guanhua , Kartvelishvili Alex , Kartvelishvili Magdalena , Simm Malgorzata
Published: April 2014

The identity and activity of several anti-HIV soluble factor(s) secreted by CD8 and CD4 T lymphocytes have been determined; however, some of them still await definition. We have established an HIV-1-resistant, transformed CD4 T cell line that secretes HIV-1 resistance protein(s). Our studies indicate that this protein(s), called HIV-1 resistance factor (HRF), inhibits transcription of the virus by interfering with the activity of NF-κB. In the present report we identified the site at which HRF exerts this inhibition by evaluating a set of discrete events in NF-κB action. We tested the κB oligonucleotide binding activity in nuclei of resistant cells, nuclear translocation and binding to the HIV-1 long terminal repeat of p65 and p50 proteins from susceptible cells after exposure to HRF, and the binding of recombinant p50 to the κB oligonucleotide in vitro as affected by prior or simultaneous exposure to HRF. The results of this experimental schema indicate that HRF interacts with p50 after it enters the nucleus, but before its binding to DNA and that this interaction impedes the formation of an NF-κB-DNA complex required for the promotion of transcription. These findings suggest that HRF mediates a novel innate immune response to virus infection.
Protease-Activated Receptor-2 Activation Induces Acute Lung Inflammation by Neuropeptide-Dependent Mechanisms
Authors: Su Xiao , Camerer Eric , Hamilton Justin R. , Coughlin Shaun R. , Matthay Michael A.
Published: April 2014

Protease-activated receptors (PARs) and tachykinin-immunoreactive fibers are located in the lung as sentries to respond to a variety of pathological stimuli. The effects of PAR activation on the lung have not been adequately studied. We report on the effects of instilling PAR-activating peptides (PAR-APs, including PAR1-, PAR2-, and PAR4-AP) into the lungs of ventilated or spontaneously breathing mice. PAR2-AP, but not PAR1-AP or PAR4-AP, caused a sharp increase in lung endothelial and epithelial permeability to protein, extravascular lung water, and airway tone. No responses to PAR2-AP were detected in PAR2 knockout mice. In bronchoalveolar lavage, PAR2 activation caused 8- and 5-fold increase in MIP-2 and substance P levels, respectively, and a 12-fold increase in the number of neutrophils. Ablation of sensory neurons (by capsaicin) markedly decreased the PAR2-mediated airway constriction, and virtually abolished PAR2-mediated pulmonary inflammation and edema, as did blockade of NK1 or NK2 receptors. Thus, PAR2 activation in the lung induces airway constriction, lung inflammation, and protein-rich pulmonary edema. These effects were either partly or completely neuropeptide dependent, suggesting that PAR2 can cause lung inflammation by a neurogenic mechanism.
IL-Converting Enzyme/Caspase-1 Inhibitor VX-765 Blocks the Hypersensitive Response to an Inflammatory Stimulus in Monocytes from Familial Cold Autoinflammatory Syndrome Patients
Authors: Stack Jeffrey H. , Beaumont Kevin , Larsen Paul D. , Straley Kimberly S. , Henkel Greg W. , Randle John C. R. , Hoffman Hal M.
Published: April 2014

Familial cold autoinflammatory syndrome (FCAS) and the related autoinflammatory disorders, Muckle-Wells syndrome and neonatal onset multisystem inflammatory disease, are characterized by mutations in the CIAS1 gene that encodes cryopyrin, an adaptor protein involved in activation of IL-converting enzyme/caspase-1. Mutations in cryopyrin are hypothesized to result in abnormal secretion of caspase-1-dependent proinflammatory cytokines, IL-1β and IL-18. In this study, we examined cytokine secretion in PBMCs from FCAS patients and found a marked hyperresponsiveness of both IL-1β and IL-18 secretion to LPS stimulation, but no evidence of increased basal secretion of these cytokines, or alterations in basal or stimulated pro-IL-1β levels. VX-765, an orally active IL-converting enzyme/caspase-1 inhibitor, blocked IL-1β secretion with equal potency in LPS-stimulated cells from FCAS and control subjects. These results further link mutations in cryopyrin with abnormal caspase-1 activation, and support the clinical testing of caspase-1 inhibitors such as VX-765 in autoinflammatory disorders.
Cytokine Production by Skin-Derived Mast Cells: Endogenous Proteases Are Responsible for Degradation of Cytokines
Authors: Zhao Wei , Oskeritzian Carole A. , Pozez Andrea L. , Schwartz Lawrence B.
Published: April 2014

The current study characterizes the cytokine protein (ELISA) and mRNA (gene array and RT-PCR) profiles of skin-derived mast cells cultured under serum-free conditions when activated by cross-linking of FcεRI. Prior to mast cell activation, mRNA only for TNF-α was detected, while after activation mRNA for IL-5, IL-6, IL-13, TNF-α, and GM-CSF substantially increased, and for IL-4 it minimally increased. However, at the protein level certain recombinant cytokines, as measured by ELISAs, were degraded by proteases released by these skin-derived mast cells. IL-6 and IL-13 were most susceptible, followed by IL-5 and TNF-α; GM-CSF was completely resistant. These observations also held for the endogenous cytokines produced by activated mast cells. By using protease inhibitors, chymase and cathepsin G, not tryptase, were identified in the mast cell releasates as the likely culprits that digest these cytokines. Their cytokine-degrading capabilities were confirmed with purified chymase and cathepsin G. Soy bean trypsin inhibitor, when added to mast cell releasates, prevented the degradation of exogenously added cytokines and, when added to mast cells prior to their activation, prevented degradation of susceptible endogenous cytokines without affecting either degranulation or GM-CSF production. Consequently, substantial levels of IL-5, IL-6, IL-13, TNF-α, and GM-CSF were detected 24–48 h after mast cells had been activated, while none were detected 15 min after activation, by which time preformed granule mediators had been released. IL-4 was not detected at any time point. Thus, unless cytokines are protected from degradation by endogenous proteases, cytokine production by human mast cells with chymase and cathepsin G cells may be grossly underestimated.
Mechanisms of Peripheral Tolerance following Intracameral Inoculation Are Independent of IL-13 or STAT6
Authors: Nakamura Takahiko , Terajewicz Ania , Stein-Streilein Joan
Published: April 2014

The peripheral tolerance that is elicited by the anterior chamber-associated immune deviation (ACAID) protocol is characterized by impairment of Th1 responses such as delayed-type hypersensitivity. It has been proposed that suppression of Th1 responses is mediated by a deviation toward Th2 responses. Because NKT cells have a prominent role in ACAID and NKT cell-derived IL-13 is required in a tumor model of tolerance, we postulated that NKT cell-derived Th2 cytokines might have a role in ACAID. However, contrary to the tumor model, in this study we show that NKT cells from IL-13-deficient mice or IL-4/IL-13 double deficient mice were able to reconstitute the capability of Jα18-deficient mice (lacking invariant NKT) to develop peripheral tolerance postintracameral inoculation of Ag. Also, we were able to induce peripheral tolerance directly in IL-13-deficient, IL-4/IL-13-double deficient, and STAT6-deficient mice by inoculation of Ag into their eye. We conclude that neither IL-4 nor IL-13 cytokines are required for the generation of efferent CD8+ T regulatory cells during eye-induced peripheral tolerance. We propose that Ags inoculated into the anterior chamber of the eye induce the immunoresponse to deviate from producing immune T effector cells to producing efferent T regulatory cells, rather than deviating from Th1- to Th2-type effector cells.
CCR3 Expression and Function in Asthmatic Airway Smooth Muscle Cells
Authors: Joubert Philippe , Lajoie-Kadoch Stéphane , Labonté Isabelle , Gounni Abdelilah Soussi , Maghni Karim , Wellemans Vincent , Chakir Jamila , Laviolette Michel , Hamid Qutayba , Lamkhioued Bouchaib
Published: April 2014

Asthma is characterized by an increase in airway smooth muscle mass and a decreased distance between the smooth muscle layer and the epithelium. Furthermore, there is evidence to indicate that airway smooth muscle cells (ASMC) express a wide variety of receptors involved in the immune response. The aims of this study were to examine the expression of CCR3 on ASMC, to compare this expression between asthmatic and nonasthmatic subjects, and to determine the implications of CCR3 expression in the migration of ASMC. We first demonstrated that ASMC constitutively express CCR3 at both mRNA and protein levels. Interestingly, TNF-α increases ASMC surface expression of CCR3 from 33 to 74%. Furthermore, using FACS analysis, we found that ASMC CCR3 is expressed to a greater degree in asthmatic vs control subjects (95 vs 75%). Functionality of the receptor was demonstrated by calcium assay; the addition of CCR3 ligand eotaxin to ASMC resulted in an increase in intracellular calcium production. Interestingly, ASMC was seen to demonstrate a positive chemotactic response to eotaxin. Indeed, ASMC significantly migrated toward 100 ng/ml eotaxin (2.2-fold increase, compared with control). In conclusion, the expression of CCR3 by ASMC is increased in asthmatics, and our data show that a CCR3 ligand such as eotaxin induces migration of ASMC in vitro. These results may suggest that eotaxin could be involved in the increased smooth muscle mass observed in asthmatics through the activation of CCR3.
Delivery of Dendritic Cells Engineered to Secrete IFN-α into Central Nervous System Tumors Enhances the Efficacy of Peripheral Tumor Cell Vaccines: Dependence on Apoptotic Pathways
Authors: Kuwashima Naruo , Nishimura Fumihiko , Eguchi Junichi , Sato Hidemitsu , Hatano Manabu , Tsugawa Takahiko , Sakaida Tsukasa , Dusak Jill E. , Fellows-Mayle Wendy K. , Papworth Glenn D. , Watkins Simon C. , Gambotto Andrea , Pollack Ian F. , Storkus Walter J. , Okada Hideho
Published: April 2014

We tested whether modulation of the CNS-tumor microenvironment by delivery of IFN-α-transduced dendritic cells (DCs: DC-IFN-α) would enhance the therapeutic efficacy of peripheral vaccinations with cytokine-gene transduced tumor cells. Mice bearing intracranial GL261 glioma or MCA205 sarcoma received peripheral immunizations with corresponding irradiated tumor cells engineered to express IL-4 or GM-CSFs, respectively, as well as intratumoral delivery of DC-IFN-α. This regimen prolonged survival of the animals and induced tumor-specific CTLs that expressed TRAIL, which in concert with perforin and Fas ligand (FasL) was involved in the tumor-specific CTL activity of these cells. The in vivo antitumor activity associated with this approach was abrogated by administration of neutralizing mAbs against TRAIL or FasL and was not observed in perforin−/−, IFN-γ−/−, or FasL−/− mice. Transduction of the tumor cells with antiapoptotic protein cellular FLIP rendered the gene-modified cells resistant to TRAIL- or FasL-mediated apoptosis and to CTL killing activity in vitro. Furthermore, the combination therapeutic regimen was ineffective in an intracranial cellular FLIP-transduced MCA205 brain tumor model. These results suggest that the combination of intratumoral delivery of DC-IFN-α and peripheral immunization with cytokine-gene transduced tumor cells may be an effective therapy for brain tumors that are sensitive to apoptotic signaling pathways.
Directing Transition from Innate to Acquired Immunity: Defining a Role for IL-6
Authors: Jones Simon A.
Published: April 2014

Appropriate control of leukocyte recruitment and activation is a fundamental requirement for competent host defense and resolving inflammation. A pivotal event that defines the successful outcome of any inflammatory event is the transition from innate to acquired immunity. In IL-6 deficiency, this process appears defective, and a series of in vivo studies have documented important roles for IL-6 in both the resolution of innate immunity and the development of acquired immune responses. Within this review, particular attention will be given to the regulatory properties of the soluble IL-6 receptor and how its activity may affect chronic disease progression.
Cutting Edge: Innate Immunity Conferred by B Cells Is Regulated by Caspase-8
Authors: Beisner Daniel R. , Ch’en Irene L. , Kolla Ravi V. , Hoffmann Alexander , Hedrick Stephen M.
Published: April 2014

Caspase-8 is an essential component of death receptor-mediated apoptosis. Along with Fas-associated death domain protein, it is also essential for T cell proliferation in response to antigenic or mitogenic stimuli. To determine whether caspase-8 is also required for B cell proliferation, we generated mice with a B cell-specific Casp8 deficiency. Unlike T cells, caspase-8 was not required for Ag receptor-driven proliferation or Ab formation. Rather, Casp8-deficient B cells failed to proliferate in response to dsRNA and LPS, ligands for TLR3 and TLR4, respectively, but responded normally to the TLR9 agonist CpG DNA. Similarly, Ab production to trinitrophenol-LPS was selectively reduced in B cell-specific Casp8-deficient mice. The activation of NF-κB or IFN regulatory factor 3 was found to be unaffected by the loss of caspase-8, implicating it in a novel pathway important for some forms of innate immunity mediated by B cells.
Neutrophils Lacking Platelet-Endothelial Cell Adhesion Molecule-1 Exhibit Loss of Directionality and Motility in CXCR2-Mediated Chemotaxis
Authors: Wu Yue , Stabach Paul , Michaud Michael , Madri Joseph A.
Published: April 2014

Time-lapsed videomicroscopy was used to study the migration of platelet-endothelial cell adhesion molecule-1-deficient (PECAM-1−/−) murine neutrophils undergoing chemotaxis in Zigmond chambers containing IL-8, KC, or fMLP gradients. PECAM-1−/− neutrophils failed to translocate up the IL-8, KC, and fMLP gradients. Significant reductions in cell motility and cell spreading were also observed in IL-8 or KC gradients. In wild-type neutrophils, PECAM-1 and F-actin were colocalized at the leading fronts of polarized cells toward the gradient. In contrast, in PECAM-1−/− neutrophils, although F-actin also localized to the leading front of migrating cells, F-actin polymerization was unstable, and cycling was remarkably increased compared with that of wild-type neutrophils. This may be due to the decreased cytokine-induced mobilization of the actin-binding protein, moesin, into the cytoskeleton of PECAM-1−/− neutrophils. PECAM-1−/− neutrophils also exhibited intracellularly dislocalized Src homology 2 domain containing phosphatase 1 (SHP-1) and had less IL-8-induced SHP-1 phosphatase activity. These results suggest that PECAM-1 regulates neutrophil chemotaxis by modulating cell motility and directionality, in part through its effects on SHP-1 localization and activation.
Transgenic Expression of Helios in B Lineage Cells Alters B Cell Properties and Promotes Lymphomagenesis
Authors: Dovat Sinisa , Montecino-Rodriguez Encarnacion , Schuman Valerie , Teitell Michael A. , Dorshkind Kenneth , Smale Stephen T.
Published: April 2014

Helios, a member of the Ikaros family of DNA-binding proteins, is expressed in multipotential lymphoid progenitors and throughout the T lineage. However, in most B lineage cells, Helios is not expressed, suggesting that its absence may be critical for B cell development and function. To test this possibility, transgenic mice were generated that express Helios under the control of an Ig μ enhancer. Commitment to the B cell lineage was unaltered in Helios transgenic mice, and numbers of surface IgM+ B cells were normal in the bone marrow and spleen. However, both bone marrow and splenic B cells exhibited prolonged survival and enhanced proliferation. B cells in Helios transgenic mice were also hyperresponsive to Ag stimulation. These alterations were observed even though the concentration of ectopic Helios in B lineage cells, like that of endogenous Helios in thymocytes, was well below the concentration of Ikaros. Further evidence that ectopic Helios expression contributes to B cell abnormalities was provided by the observation that Helios transgenic mice developed metastatic lymphoma as they aged. Taken together, these results demonstrate that silencing of Helios is critical for normal B cell function.
Selectively Impaired CD8+ but Not CD4+ T Cell Cycle Arrest during Priming as a Consequence of Dendritic Cell Interaction with Plasmodium-Infected Red Cells
Authors: Pouniotis Dodie S. , Proudfoot Owen , Bogdanoska Violeta , Scalzo Karen , Kovacevic Svetozar , Coppel Ross L. , Plebanski Magdalena
Published: April 2014

Individuals living in malaria-endemic areas show generally low T cell responses to malaria Ags. In this study, we show murine dendritic cell (DC) interaction with parasitized erythrocytes (pRBC) arrested their maturation, resulting in impaired ability to stimulate naive, but not recall T cell responses in vitro and in vivo. Moreover, within the naive T cell population, pRBC-treated DC were selectively deficient in priming CD8+ but not CD4+ T cells. Indeed, DC that had taken up pRBC were shown for the first time to efficiently prime CD4+ T cell responses to a known protective merozoite Ag, MSP4/5. In contrast, impaired priming resulted in decreases in both proliferation and cytokine production by CD8+ T cells. Deficient priming was observed to both a model and a Plasmodium berghei-specific CD8+ T cell epitope. The mechanisms underlying the inability of parasite-treated DC to prime CD8+ T cells were explored. pRBC treatment of DC from wild-type C57BL/6, but not from IL-10 knockout animals, suppressed DC-mediated T cell priming across a Transwell, suggesting active IL-10-dependent suppression. CD8+ T cells were arrested at the G0 stage of the cell cycle after two cell divisions post-Ag stimulation. The proliferation arrest was partially reversible by the addition of IL-2 or IL-7 to responder cultures. These results suggest that in malaria-endemic areas, priming of CD8+ T cell responses may be more difficult to induce via vaccination than the priming of CD4+ T cells. Moreover, pathogens may selectively target the CD8+ T cell arm of protective immunity for immune evasion.
Modulation of the Induction of Lung and Airway Allergy in the Offspring of IFN-γ-Treated Mother Mice
Authors: Lima Carla , Souza Valdenia Maria Oliveira , Faquim-Mauro Eliana Lima , Hoshida Mara Sandra , Bevilacqua Estela , Macedo Mahasti Sahihi , Tavares-de-Lima Wothan , Vargaftig B. Boris
Published: April 2014

Recent studies have highlighted the influence of fetal/maternal interactions on the development of asthma. Because IFN-γ reduces Th2-mediated allergic responses, we assessed its capacity to modulate asthma in the offspring when injected into mothers during pregnancy. IFN-γ was injected in CD1 female mice on day 6.5 of gestation. Immediately after birth, male newborns were housed in cages with interchanged mothers: the offspring from IFN-γ-treated mothers were breastfed by normal mothers (IFN/nor), and those from normal mothers were breastfed by IFN-γ-treated (Nor/IFN) or normal mothers (Nor/nor). Immediately after weaning, the spleen cells from IFN/nor and Nor/IFN mice produced less IL-4 and more IFN-γ than Nor/nor mice when stimulated with Con A. At the age of 6–7 wk, mice were immunized with OVA on days 0 and 7. From day 14 to 16, they were exposed to aerosolized OVA. The bronchoalveolar lavage fluid from Nor/nor mice showed eosinophilia, a large number of these cells being present in perivascular and peribronchial regions of lung tissues. IFN/nor or Nor/IFN mice showed greatly reduced eosinophil numbers in bronchoalveolar lavage fluid. In addition, lung sections from IFN/nor, but not Nor/IFN mice showed almost normal histology. In OVA-sensitized IFN/nor and Nor/IFN mice, the production of IFN-γ, IL-4, and IL-5 by spleen cells was significantly reduced as compared with cells from the OVA-sensitized Nor/nor group. IgE and anaphylactic IgG1 were also reduced in plasma of IFN/nor mice. In conclusion, the presence of IFN-γ during pregnancy confers to the fetus a protection against allergenic provocations in the adult life.
Differences in Macrophage Activation by Bacterial DNA and CpG-Containing Oligonucleotides
Authors: Roberts Tara L. , Dunn Jasmyn A. , Terry Tamsin D. , Jennings Michael P. , Hume David A. , Sweet Matthew J. , Stacey Katryn J.
Published: April 2014

Bacterial DNA activates mouse macrophages, B cells, and dendritic cells in a TLR9-dependent manner. Although short ssCpG-containing phosphodiester oligonucleotides (PO-ODN) can mimic the action of bacterial DNA on macrophages, they are much less immunostimulatory than Escherichia coli DNA. In this study we have assessed the structural differences between E. coli DNA and PO-ODN, which may explain the high activity of bacterial DNA on macrophages. DNA length was found to be the most important variable. Double-strandedness was not responsible for the increased activity of long DNA. DNA adenine methyltransferase (Dam) and DNA cytosine methyltransferase (Dcm) methylation of E. coli DNA did not enhance macrophage NO production. The presence of two CpG motifs on one molecule only marginally improved activity at low concentration, suggesting that ligand-mediated TLR9 cross-linking was not involved. The major contribution was from DNA length. Synthetic ODN >44 nt attained the same levels of activity as bacterial DNA. The response of macrophages to CpG DNA requires endocytic uptake. The length dependence of the CpG ODN response was found to correlate with the presence in macrophages of a length-dependent uptake process for DNA. This transport system was absent from B cells and fibroblasts.
Heat Shock Protein 60 Activates B Cells via the TLR4-MyD88 Pathway
Authors: Cohen-Sfady Michal , Nussbaum Gabriel , Pevsner-Fischer Meirav , Mor Felix , Carmi Pnina , Zanin-Zhorov Alexandra , Lider Ofer , Cohen Irun R.
Published: April 2014

We recently reported that soluble 60-kDa heat shock protein (HSP60) can directly activate T cells via TLR2 signaling to enhance their Th2 response. In this study we investigated whether HSP60 might also activate B cells by an innate signaling pathway. We found that human HSP60 (but not the Escherichia coli GroEL or the Mycobacterial HSP65 molecules) induced naive mouse B cells to proliferate and to secrete IL-10 and IL-6. In addition, the HSP60-treated B cells up-regulated their expression of MHC class II and accessory molecules CD69, CD40, and B7-2. We tested the functional ability of HSP60-treated B cells to activate an allogeneic T cell response and found enhanced secretion of both IL-10 and IFN-γ by the responding T cells. The effects of HSP60 were found to be largely dependent on TLR4 and MyD88 signaling; B cells from TLR4-mutant mice or from MyD88 knockout mice showed decreased responses to HSP60. Care was taken to rule out contamination of the HSP60 with LPS as a causative factor. These findings add B cells to the complex web of interactions by which HSP60 can regulate immune responses.
Broad Repertoire of the CD4+ Th Cell Response in Spontaneously Controlled Hepatitis C Virus Infection Includes Dominant and Highly Promiscuous Epitopes
Authors: Schulze zur Wiesch Julian , Lauer Georg M. , Day Cheryl L. , Kim Arthur Y. , Ouchi Kei , Duncan Jared E. , Wurcel Alysse G. , Timm Joerg , Jones Andrea M. , Mothe Bianca , Allen Todd M. , McGovern Barbara , Lewis-Ximenez Lia , Sidney John , Sette Alessandro , Chung Raymond T. , Walker Bruce D.
Published: April 2014

A vigorous hepatitis C virus (HCV)-specific Th cell response is regarded as essential to the immunological control of HCV viremia. The aim of this study was to comprehensively define the breadth and specificity of dominant HCV-specific CD4+ T cell epitopes in large cohorts of subjects with chronic and spontaneously resolved HCV viremia. Following in vitro stimulation of PBMC, HCV-specific cell cultures from each subject were screened with an overlapping panel of synthetic 20-mer peptides spanning the entire HCV polyprotein. Of 22 subjects who spontaneously controlled HCV viremia, all recognized at least one of a group of six epitopes situated within the nonstructural (NS) proteins NS3, NS4, and NS5, each of which was detected by >30% of subjects, but most subjects recognized additional, more heterogeneous specificities. In contrast, none of the most frequently targeted epitopes was detected by >5% of persons with chronic infection. The most frequently recognized peptides showed promiscuous binding to multiple HLA-DR molecules in in vitro binding assays and were restricted by different HLA-DR molecules in functional assays in different persons. These data demonstrate that predominant CD4+ T cell epitopes in persons with resolved HCV infection are preferentially located in the nonstructural proteins and are immunogenic in the context of multiple class II molecules. This comprehensive characterization of CD4+ T cell epitopes in resolved HCV infection provides important information to facilitate studies of immunopathogenesis and HCV vaccine design and evaluation.
A Peptide of Glutamic Acid Decarboxylase 65 Can Recruit and Expand a Diabetogenic T Cell Clone, BDC2.5, in the Pancreas
Authors: Dai Yang D. , Jensen Kent P. , Lehuen Agnes , Masteller Emma L. , Bluestone Jeffrey A. , Wilson Darcy B. , Sercarz Eli E.
Published: April 2014

Self peptide-MHC ligands create and maintain the mature T cell repertoire by positive selection in the thymus and by homeostatic proliferation in the periphery. A low affinity/avidity interaction among T cells, self peptides, and MHC molecules has been suggested for these events, but it remains unknown whether or how this self-interaction is involved in tolerance and/or autoimmunity. Several lines of evidence implicate the glutamic acid decarboxylase 65 (GAD-65) peptide, p524–543, as a specific, possibly low affinity, stimulus for the spontaneously arising, diabetogenic T cell clone BDC2.5. Interestingly, BDC2.5 T cells, which normally are unresponsive to p524–543 stimulation, react to the peptide when provided with splenic APC obtained from mice immunized with the same peptide, p524–543, but not, for example, with hen egg white lysozyme. Immunization with p524–543 increases the susceptibility of the NOD mice to type 1 diabetes induced by the adoptive transfer of BDC2.5 T cells. In addition, very few CFSE-labeled BDC2.5 T cells divide in the recipient’s pancreas after transfer into a transgenic mouse that overexpresses GAD-65 in B cells, whereas they divide vigorously in the pancreas of normal NOD recipients. A special relationship between the BDC2.5 clone and the GAD-65 molecule is further demonstrated by generation of a double-transgenic mouse line carrying both the BDC2.5 TCR and GAD-65 transgenes, in which a significant reduction of BDC2.5 cells in the pancreas has been observed, presumably due to tolerance induction. These data suggest that unique and/or altered processing of self Ags may play an essential role in the development and expansion of autoreactive T cells.
IFN-γ-Primed Macrophages Exhibit Increased CCR2-Dependent Migration and Altered IFN-γ Responses Mediated by Stat1
Authors: Hu Xiaoyu , Park-Min Kyung-Hyun , Ho Hao H. , Ivashkiv Lionel B.
Published: April 2014

Priming of macrophages with IFN-γ increases cellular responsiveness to inflammatory stimuli, including IFN-γ itself. We described previously that priming with subactivating concentrations of IFN-γ increased Stat1 expression and resulted in enhanced activation of Stat1 and of a subset of IFN-γ-responsive genes when primed macrophages were restimulated with low doses of IFN-γ. In this study, we determined the effects of IFN-γ priming on the macrophage transcriptome and on transcriptional responses to high saturating concentrations of IFN-γ. At baseline, primed macrophages expressed a small subset of IFN-γ-inducible genes, including CCR2, and exhibited increased migration in response to CCL2. Activation of gene expression by high concentrations of IFN-γ was altered in primed macrophages, such that activation of a subset of IFN-γ-inducible genes was attenuated. A majority of genes in this “less induced” category corresponded to genes that are induced by IFN-γ via Stat1-independent but Stat3-dependent pathways and have been implicated in inflammatory tissue destruction. One mechanism of attenuation of gene expression was down-regulation of Stat3 function by increased levels of Stat1. These results reveal that priming enhances migration to inflammatory chemokines and identify IFN-γ-inducible genes whose expression is attenuated by high levels of Stat1. The increase in Stat1 expression during priming provides a mechanism by which physiological regulation of the relative abundance of Stat1 and Stat3 impacts on gene expression. Our results also suggest that, in addition to inducing hypersensitivity to inflammatory stimuli, IFN priming delivers a homeostatic signal by attenuating IFN-γ induction of certain tissue-destructive genes.
Induction of Regulatory Properties in Dendritic Cells by Vα14 NKT Cells
Authors: Kojo Satoshi , Seino Ken-ichiro , Harada Michishige , Watarai Hiroshi , Wakao Hiroshi , Uchida Tetsuro , Nakayama Toshinori , Taniguchi Masaru
Published: April 2014

Vα14 NKT cells exhibit various immune regulatory properties in vivo, but their precise mechanisms remain to be solved. In this study, we demonstrate the mechanisms of generation of regulatory dendritic cells (DCs) by stimulation of Vα14 NKT cells in vivo. After repeated injection of α-galactosylceramide (α-GalCer) into mice, splenic DCs acquired properties of regulatory DCs in IL-10-dependent fashion, such as nonmatured phenotypes and increased IL-10 but reduced IL-12 production. The unique cytokine profile in these DCs appears to be regulated by ERK1/2 and IκBNS. These DCs also showed an ability to suppress the development of experimental allergic encephalomyelitis by generating IL-10-producing regulatory CD4 T cells in vivo. These findings contribute to explaining how Vα14 NKT cells regulate the immune responses in vivo.
Cysteine-Tailed Class I-Binding Peptides Bind to CpG Adjuvant and Enhance Primary CTL Responses
Authors: Wettstein Peter J. , Borson Nancy D. , Park Jewn G. , McNallan Kelly T. , Reed Ann M.
Published: April 2014

Immunostimulatory CpG motifs in synthetic oligonucleotides can be effective adjuvants for the priming of CTLs. We first observed that a single male-specific peptide (KCSRNRQYL) (HY2) was more efficient than another male-specific peptide (WMHHNMDLI) (HY1) at priming IFN-γ-secreting CTLs in vivo when combined with lipid A and CpG and that it also visibly precipitated CpG. The addition of the six N-terminal residues (KCSRNR) from HY2 to HY1 yielded a peptide, KCSRNR-HY1, that both precipitated CpG and primed increased numbers of HY1-specific CTLs. We refer to this type of peptide as a primotope that includes a class I binding peptide tailed with amino acids that increase priming. Ala residues were substituted for the Arg/Lys residues (ACSANA-HY1), and these substitutions did not reduce in vivo priming potential. However, the substitution of Ala for Cys (KASRNR-HY1) resulted in the complete loss of priming, demonstrating the importance of Cys for in vivo priming when mixed with CpG. This result suggested that increased priming was based in disulfide bonding between Cys residues and internal phosphorothioate groups of synthetic CpG. The addition of Cys-bearing primotopes to radiolabeled CpG with a single thioate group resulted in the appearance of a new band that was inhibited by 1) Cys > Ala substitution and 2) reduction and alkylation of CpG. These results reveal a novel mechanism for complexing class I binding peptides and CpG adjuvant for development of new peptide-adjuvant combinations for vaccines for cancer and infectious diseases.
Distinctive Lack of CD48 Expression in Subsets of Human Dendritic Cells Tunes NK Cell Activation
Authors: Morandi Barbara , Costa Roberta , Falco Michela , Parolini Silvia , De Maria Andrea , Ratto Giovanni , Mingari Maria Cristina , Melioli Giovanni , Moretta Alessandro , Ferlazzo Guido
Published: April 2014

CD48 is a glycosyl phosphatidylinositol anchor protein known to be virtually expressed by all human leukocytes. Its ligand, 2B4, is a signaling lymphocyte activation molecule-related receptor involved in NK cell activation. Because dendritic cells (DCs) are strong inducers of NK cell functions, we analyzed the expression of CD48 in different human DC subsets. We observed that monocytes differentiating in DCs promptly down-regulate CD48. Similarly, DCs isolated from inflamed lymph nodes generally do not express CD48. Plasmocytoid DCs do not express CD48 either, whereas myeloid DCs harbored in blood, bone marrow, and thymus express it. In addition, we showed that CD48 expression in DCs affects NK cell functions during NK/DC cross-talk, because NK cells obtained from normal donors and from X-linked lymphoproliferative disease patients are, respectively, triggered or inhibited by DCs expressing surface CD48. Remarkably, IFN-γ production by lymph node NK cells, in contrast to blood NK cells, can be negatively modulated by 2B4/CD48 interactions, indicating a 2B4 inhibitory pathway in lymph node NK cells. Therefore, the CD48 deficiency of DCs harbored in inflamed lymph nodes that we report in this study might be relevant to successfully activate lymph node NK cells in the early phase of the immune response. Our results show that distinct subsets of human DCs, differently from all other mononuclear hemopoietic cells, specifically do not express CD48. Moreover, the expression of CD48 depends on the anatomic location of DCs and might be related to the tissue-specific 2B4 function (activating or inhibitory) of the NK cells with which they interact.
Complement C3a Enhances CXCL12 (SDF-1)-Mediated Chemotaxis of Bone Marrow Hematopoietic Cells Independently of C3a Receptor
Authors: Honczarenko Marek , Ratajczak Mariusz Z. , Nicholson-Weller Anne , Silberstein Leslie E.
Published: April 2014

Complement C3a promotes CXCL12-induced migration and engraftment of human and murine hemopoietic progenitor cells, suggesting a cross-influence between anaphylatoxin and chemokine axes. Here we have explored the underlying mechanism(s) of complement anaphylatoxin and chemokine cooperation. In addition to C3a, C3a-desArg and C4a but not C5a, are potent enhancers of CXCL12-induced chemotaxis of human and murine bone marrow (BM) stem/progenitor cells and B lineage cells. C3a enhancement of chemotaxis is chemokine specific because it is also observed for chemotaxis to CCL19 but not to CXCL13. The potentiating effect of C3a on CXCL12 is independent of the classical C3a receptor (C3aR). First, human BM CD34+ and B lineage cells do not express C3aR by flow cytometry. Second, the competitive C3aR inhibitor SB290157 does not affect C3a-mediated enhancement of CXCL12-induced chemotaxis. Third, enhancement of chemotaxis of hemopoietic cells is also mediated by C3a-desArg, which does not bind to C3aR. Finally, C3a enhances CXCL12-induced chemotaxis of BM cells from C3aR knockout mice similar to BM cells from wild-type mice. Subsequent studies revealed that C3a increased the binding affinity of CXCL12 to human CXCR4+/C3aR−, REH pro-B cells, which is compatible with a direct interaction between C3a and CXCL12. BM stromal cells were able to generate C3a, C3a-desArg, C4a, as well as CXCL12, suggesting that this pathway could function in vivo. Taken together, we demonstrate a C3a-CXCL12 interaction independent of the C3aR, which may provide a mechanism to modulate the function of CXCL12 in the BM microenvironment.