bluuebunny/crossref_metadata_2025 huggingface dataset:
Withdrawal of Stimulation May Initiate the Transition of Effector to Memory CD4 Cells
Authors: Harbertson Judith , Biederman Elana , Bennett Kristin E. , Kondrack Robyn M. , Bradley Linda M.
Published: April 2014

The initial steps that determine development of memory in CD4 cells are unknown. To distinguish an intrinsic capacity of effectors to become memory cells from contributions of as yet undefined survival factors, we analyzed the effects of withdrawal of signals via TCR, costimulation, and cytokines from Th1 or Th2 primary effectors induced in vitro from TCR-transgenic CD4 cells. Withdrawal of stimulation caused the transition of effectors to resting populations with a memory phenotype that did not undergo division following transfer to normal syngeneic recipients. The return of effectors to rest was accompanied by acquisition of the capacity to function as memory cells in vivo as defined by extended persistence and a more rapid response to Ag in vivo than naive cells in adoptive hosts. Upon challenge with Ag, these in vitro-rested Th1 and Th2 cells were similar to long-term in vivo-rested memory cells, but distinct from in vitro-generated primary effectors and in vivo-restimulated memory effectors by their ability to resist apoptosis. Cessation of stimulation may occur when activated CD4 cells exit lymphoid tissues after priming and transition to memory may be initiated if effectors either fail to gain access to Ag in peripheral tissues where restimulation can lead to activation-induced cell death or do not receive sufficient stimuli to continue a response. Our results suggest that the first stage leading to stable CD4 memory could occur stochastically and independently of instructional processes and as such, the development of memory may be a default pathway when signals that direct responses are not received.
Synergy of IL-12 and IL-18 for IFN-γ Gene Expression: IL-12-Induced STAT4 Contributes to IFN-γ Promoter Activation by Up-Regulating the Binding Activity of IL-18-Induced Activator Protein 1
Authors: Nakahira Masakiyo , Ahn Hyun-Jong , Park Woong-Ryeon , Gao Ping , Tomura Michio , Park Cheung-Seog , Hamaoka Toshiyuki , Ohta Tsunetaka , Kurimoto Masashi , Fujiwara Hiromi
Published: April 2014

IL-12 and IL-18 synergistically enhance IFN-γ mRNA transcription by activating STAT4 and AP-1, respectively. However, it is still unknown how STAT4/AP-1 elicit IFN-γ promoter activation. Using an IL-12/IL-18-responsive T cell clone, we investigated the mechanisms underlying synergistic enhancement of IFN-γ mRNA expression induced by these two cytokines. Synergy was observed in a reporter gene assay using an IFN-γ promoter fragment that binds AP-1, but not STAT4. An increase in c-Jun, a component of AP-1, in the nuclear compartment was elicited by stimulation with either IL-12 or IL-18, but accumulation of serine-phosphorylated c-Jun was induced only by IL-18 capable of activating c-Jun N-terminal kinase. The binding of AP-1 to the relevant promoter sequence depended on the presence of STAT4. STAT4 bound with c-Jun, and a phosphorylated c-Jun-STAT4 complex most efficiently interacted with the AP-1-relevant promoter sequence. Enhanced cobinding of STAT4 and c-Jun to the AP-1 sequence was also observed when activated lymph node T cells were exposed to IL-12 plus IL-18. These results show that STAT4 up-regulates AP-1-mediated IFN-γ promoter activation without directly binding to the promoter sequence, providing a mechanistic explanation for IL-12/IL-18-induced synergistic enhancement of IFN-γ gene expression.
Mechanisms of Central Nervous System Viral Persistence: the Critical Role of Antibody and B Cells
Authors: Ramakrishna Chandran , Stohlman Stephen A. , Atkinson Roscoe D. , Shlomchik Mark J. , Bergmann Cornelia C.
Published: April 2014

Contributions of humoral and cellular immunity in controlling neurotropic mouse hepatitis virus persistence within the CNS were determined in B cell-deficient JHD and syngeneic H-2d B cell+ Ab-deficient mice. Virus clearance followed similar kinetics in all mice, confirming initial control of virus replication by cellular immunity. Nevertheless, virus reemerged within the CNS of all Ab-deficient mice. In contrast to diminished T cell responses in H-2b B cell-deficient μMT mice, the absence of B cells or Ab in the H-2d mice did not compromise expansion, recruitment into the CNS, or function of virus-specific CD4+ and CD8+ T cells. The lack of B cells and lymphoid architecture thus appears to manifest itself on T cell responses in a genetically biased manner. Increasing viral load did not enhance frequencies or effector function of virus-specific T cells within the CNS, indicating down-regulation of T cell responses. Although an Ab-independent antiviral function of B cells was not evident during acute infection, the presence of B cells altered CNS cellular tropism during viral recrudescence. Reemerging virus localized almost exclusively to oligodendroglia in B cell+ Ab-deficient mice, whereas it also replicated in astrocytes in B cell-deficient mice. Altered tropism coincided with distinct regulation of CNS virus-specific CD4+ T cells. These data conclusively demonstrate that the Ab component of humoral immunity is critical in preventing virus reactivation within CNS glial cells. B cells themselves may also play a subtle role in modulating pathogenesis by influencing tropism.
CpG Are Efficient Adjuvants for Specific CTL Induction Against Tumor Antigen-Derived Peptide
Authors: Miconnet Isabelle , Koenig Sylvain , Speiser Daniel , Krieg Arthur , Guillaume Philippe , Cerottini Jean-Charles , Romero Pedro
Published: April 2014

The identification of CTL-defined tumor-associated Ags has allowed the development of new strategies for cancer immunotherapy. To potentiate the CTL responses, peptide-based vaccines require the coadministration of adjuvants. Because oligodeoxynucleotides (ODN) containing CpG motifs are strong immunostimulators, we analyzed the ability of CpG ODN to act as adjuvant of the CTL response against tumor-derived synthetic peptide in the absence or presence of IFA. Mice transgenic for a chimeric MHC class I molecule were immunized with a peptide analog of MART-1/Melan-A26–35 in the presence of CpG ODN alone or CpG ODN emulsified in IFA. The CTL response was monitored ex vivo by tetramer staining of lymphocytes. In blood, spleen, and lymph nodes, peptide mixed with CpG ODN alone was able to elicit a stronger systemic CTL response as compared with peptide emulsified in IFA. Moreover, CpG ODN in combination with IFA further enhanced the CTL response in terms of the frequency of tetramer+CD8+ T cells ex vivo. The CTL induced in vivo against peptide analog in the presence of CpG ODN are functional, as they were able to recognize and kill melanoma cells in vitro. Overall, these results indicate that CpG ODN by itself is a good candidate adjuvant of CTL response and can also enhance the effect of classical adjuvant.
Regulation of Human Igλ Light Chain Gene Expression by NF-κB
Authors: Combriato Gabriele , Klobeck H.-Gustav
Published: April 2014

The human Igλ enhancer consists of three separated sequence elements that we identified previously by mapping DNase I-hypersensitive regions (HSS) downstream of the C region of the Igλ L chain genes (HSS-1, HSS-2, and HSS-3). It has been shown by several laboratories that expression of the H chain genes as well as the κ genes, but not the λ genes, is dependent on constitutive NF-κB proteins present in the nucleus. In this study we show by band-shift experiments, in vivo footprinting, and transient transfection assays that all three hypersensitive sites of the human Igλ enhancer contain functional NF-κB sites that act synergistically on expression. We further show that the chicken λ enhancer also contains a functional NF-κB site but the mouse λ enhancer contains a mutated, nonfunctional NF-κB site that is responsible for its low enhancer activity. It is possible that the inactivating mutation in the mouse Igλ enhancer was compensated for by an expansion of the Igκ L chain locus, followed by a contraction of the Igλ locus in this species.
C-Terminal Anchoring of a Peptide to Class II MHC Via the P10 Residue Is Compatible with a Peptide Bulge
Authors: Yassai Maryam , Afsari Amin , Garlie Jason , Gorski Jack
Published: April 2014

The binding of antigenic peptide to class II MHC is mediated by hydrogen bonds between the MHC and the peptide, by salt bridges, and by hydrophobic interactions. The latter are confined to a number of deeper pockets within the peptide binding groove, and peptide side chains that interact with these pockets are referred to as anchor residues. T cell recognition involves solvent-accessible peptide residues along with minor changes in MHC helical pitch induced by the anchor residues. In class I MHC there is an added level of epitope complexity that results from binding of longer peptides that bulge out into the solvent-accessible, T cell contact area. Unlike class I MHC, class II MHC does not bind peptides of discrete length, and the possibility of peptide bulging has not been clearly addressed. A peptide derived from position 24–37 of integrin β3 can either bind or not bind to the class II MHC molecule HLA DRB3*0101 based on a polymorphism at the P9 anchor. We show that the loss of binding can be compensated by changes at the P10 position. We propose that this could be an example of a class II peptide bulge. Although not as efficient as P9 anchoring, the use of P10 as an anchor adds another possible mechanism by which T cell epitopes can be generated in the class II presentation system.
In Vivo Expression of Toll-Like Receptor 2 and 4 by Renal Epithelial Cells: IFN-γ and TNF-α Mediated Up-Regulation During Inflammation
Authors: Wolfs Tim G. A. M. , Buurman Wim A. , van Schadewijk Annemarie , de Vries Bart , Daemen Marc A. R. C. , Hiemstra Pieter S. , van ’t Veer Cornelis
Published: April 2014

The reported requirement of functional Toll-like receptor (TLR)4 for resistance to Gram-negative pyelonephritis prompted us to localize the expression of TLR2 and TLR4 mRNA in the kidney at the cellular level by in situ hybridization. The majority of the constitutive TLR2 and TLR4 mRNA expression was found to be strategically located in the renal epithelial cells. Assuming that the TLR mRNA expression is representative of apical protein expression, this suggests that these cells are able to detect and react with bacteria present in the lumen of the tubules. To gain insight in the regulation of TLR expression during inflammation, we used a model for renal inflammation. Renal inflammation evoked by ischemia markedly enhanced synthesis of TLR2 and TLR4 mRNA in the distal tubular epithelium, the thin limb of Henle’s loop, and collecting ducts. The increased renal TLR4 mRNA expression was associated with significant elevation of renal TLR4 protein expression as evaluated by Western blotting. Using RT-PCR, the enhanced TLR2 and TLR4 mRNA expression was shown to be completely dependent on the action of IFN-γ and TNF-α. These results indicate a potential mechanism of increased immunosurveillance during inflammation at the site in which ascending bacteria enter the kidney tissue, i.e., the collecting ducts and the distal part of the nephron.
Dendritic Cells Are Host Cells for Mycobacteria In Vivo That Trigger Innate and Acquired Immunity
Authors: Jiao Xinan , Lo-Man Richard , Guermonprez Pierre , Fiette Laurence , Dériaud Edith , Burgaud Sophie , Gicquel Brigitte , Winter Nathalie , Leclerc Claude
Published: April 2014

In the present study, we investigated in vivo the infection and APC functions of dendritic cells (DC) and macrophages (Mφ) after administration of live mycobacteria to mice. Experiments were conducted with Mycobacterium bovis bacillus Calmette-Guerin (BCG) or a rBCG expressing a reporter Ag. Following infection of mice, DC and Mφ were purified and the presence of immunogenic peptide/MHC class II complexes was detected ex vivo on sorted cells, as was the secretion of IL-12 p40. We show in this study that DC is a host cell for mycobacteria, and we provide an in vivo detailed picture of the role of Mφ and DC in the mobilization of immunity during the early stages of a bacterial infection. Strikingly, BCG bacilli survive but remain stable in number in the DC leukocyte subset during the first 2 wk of infection. As Ag presentation by DC is rapidly lost, this suggests that DC may represent a hidden reservoir for mycobacteria.
CD28 Costimulation and Parasite Dose Combine to Influence the Susceptibility of BALB/c Mice to Infection withLeishmania major
Authors: Compton Helen L. , Farrell Jay P.
Published: April 2014

Infection with Leishmania major in BALB/c mice is accompanied by the development of a nonprotective Th2-type response. It has previously been shown that disease progression, and the activation of a Th2-type response, can occur in the absence of CD28 costimulation following the inoculation of high numbers of L. major promastigotes. In this study, we show that in the absence of CD28-B7 interactions, BALB/c mice can spontaneously resolve their infections following the inoculation of low numbers of parasites. BALB/c CD28+/+ and CD28−/− mice were inoculated with 250, 500, and 750 metacyclic parasites. The CD28−/− mice controlled their lesions, whereas the wild-type (WT) mice developed progressive nonhealing infections. Resistance to infection was associated with reduced numbers of parasites in the CD28−/− mice compared with the WT mice. Infection of the CD28−/− mice resulted in the activation of a Th1-type response as evidenced by increased levels of mRNA for IFN-γ and reduced levels of message for IL-4 and IL-10 in draining lymph nodes compared with those in WT mice. Healing of infected CD28−/− mice could also be ablated with anti-CD4 Ab treatment or treatment with anti-IFN-γ Ab. In addition, healed CD28−/− mice were resistant to a challenge infection with L. major. These results suggest that CD28 costimulation influences the in vivo activation of a Th2-type response in a manner that is dependent on the size of the parasite inoculum.
Surfactant Protein D Inhibition of Human Macrophage Uptake ofMycobacterium tuberculosisIs Independent of Bacterial Agglutination
Authors: Ferguson J. Scott , Voelker Dennis R. , Ufnar Jennifer A. , Dawson Amanda J. , Schlesinger Larry S.
Published: April 2014

The innate immune system in the lung is essential for controlling infections due to inhaled pathogens. Mycobacterium tuberculosis (M.tb) encounters components of the innate immune system when inhaled into the lung, but the consequences of these interactions are poorly understood. Surfactant protein D (SP-D) binds to and agglutinates M.tb bacilli, and reduces the uptake of the bacteria by human macrophages. In the current studies, we utilized a recombinant SP-D variant (CDM) that lacks the collagen domain to further characterize the interaction of SP-D with M.tb, and determine the effects of agglutination on bacterial uptake by human monocyte-derived macrophages. These studies demonstrate that the binding of SP-D and CDM to M.tb is saturable and inhibited by carbohydrate competition and Ca2+ chelation, implicating the carbohydrate recognition domain in the interaction. Fluorescence microscopy reveals that dodecameric SP-D leads to agglutination of the bacilli, whereas the trimeric CDM does not, demonstrating that the multivalent nature of SP-D is essential for agglutination of M.tb. However, preincubation of M.tb with increasing concentrations of SP-D or CDM leads to a concentration-dependent reduction in the uptake of the bacteria by macrophages, indicating that agglutination does not play a direct role in this observation. Finally, the reduced uptake of M.tb by SP-D is associated with reduced growth of M.tb in monocyte-derived macrophages. These studies provide direct evidence that the inhibition of phagocytosis of M.tb effected by SP-D occurs independently of the aggregation process.
Induction of TNF in Human Alveolar Macrophages As a Potential Evasion Mechanism of VirulentMycobacterium tuberculosis
Authors: Engele Matthias , Stöβel Elmar , Castiglione Kirstin , Schwerdtner Nives , Wagner Manfred , Bölcskei Pal , Röllinghoff Martin , Stenger Steffen
Published: April 2014

The ability of macrophages to release cytokines is crucial to the host response to intracellular infection. In particular, macrophage-derived TNF plays an important role in the host response to infection with the intracellular pathogen Mycobacterium tuberculosis. In mice, TNF is indispensable for the formation of tuberculous granulomas, which serve to demarcate the virulent bacterium. TNF is also implicated in many of the immunopathological features of tuberculosis. To investigate the role of TNF in the local immune response, we infected human alveolar macrophages with virulent and attenuated mycobacteria. Infection with virulent strains induced the secretion of significantly higher levels of bioactive TNF than attenuated strains correlating with their ability to multiply intracellularly. Treatment of infected macrophages with neutralizing anti-TNF Abs reduced the growth rate of intracellular bacteria, whereas bacterial replication was augmented by addition of exogenous TNF. Infected and uninfected macrophages contributed to cytokine production as determined by double-staining of M. tuberculosis and intracellular TNF. The induction of TNF by human alveolar macrophages at the site of infection permits the multiplication of intracellular bacteria and may therefore present an evasion mechanism of human pathogens.
Increased Susceptibility to Tumor Initiation and Metastasis in TNF-Related Apoptosis-Inducing Ligand-Deficient Mice
Authors: Cretney Erika , Takeda Kazuyoshi , Yagita Hideo , Glaccum Moira , Peschon Jacques J. , Smyth Mark J.
Published: April 2014

We have previously implicated TNF-related apoptosis-inducing ligand (TRAIL) in innate immune surveillance against tumor development. In this study, we describe the use of TRAIL gene-targeted mice to demonstrate the key role of TRAIL in suppressing tumor initiation and metastasis. Liver and spleen mononuclear cells from TRAIL gene-targeted mice were devoid of TRAIL expression and TRAIL-mediated cytotoxicity. TRAIL gene-targeted mice were more susceptible to experimental and spontaneous tumor metastasis, and the immunotherapeutic value of α-galactosylceramide was diminished in TRAIL gene-targeted mice. TRAIL gene-targeted mice were also more sensitive to the chemical carcinogen methylcholanthrene. These results substantiated TRAIL as an important natural effector molecule used in the host defense against transformed cells.
TNF-α Potentiates C5a-Stimulated Eosinophil Adhesion to Human Bronchial Epithelial Cells: A Role for α5β1 Integrin
Authors: Burke-Gaffney Anne , Blease Kate , Hartnell Adele , Hellewell Paul G.
Published: April 2014

Cooperative action of inflammatory mediators and adhesion molecules orchestrates eosinophil recruitment during allergic inflammation in the airways. This study investigated the mechanisms involved in increasing eosinophil adhesion to human bronchial epithelial cells (HBEC) following priming and activation of eosinophils with TNF-α and complement protein C5a, respectively. Under primed conditions, eosinophil adhesion increased 3-fold from basal (16%), and the effect was significantly greater (p < 0.05) than the increase following stimulation with C5a alone (2-fold). Eosinophil contact with HBEC was essential for priming. In contrast to C5a, adhesion of eotaxin-stimulated eosinophils to HBEC was not primed with TNF-α nor IL-5, a known eosinophil-priming agent. Priming caused activation of αMβ2 integrin; mAb against either the common β2 integrin subunit or its ICAM-1 ligand reduced the primed component of adhesion. Using mAbs against β1 or α5, but not α4 integrin subunit, together with anti-β2 integrin mAb, reduced stimulated adhesion to basal levels. Cross-linking α5β1 integrin increased αMβ2 integrin-dependent adhesion of eosinophils. There are no known adhesion molecule ligands of α5β1 integrin expressed on HBEC; however, fibronectin, the major matrix protein ligand for α5β1 integrin, was detected in association with HBEC monolayers. A mAb against fibronectin, in combination with anti-β2 integrin mAb, reduced adhesion to basal levels. In conclusion, α5β1 integrin may provide a contact-dependent costimulus for eosinophil priming that, together with TNF-α, potentiated C5a activation of αMβ2 integrin and increased eosinophil adhesion to ICAM-1. Fibronectin, associated with HBEC, may act as a ligand for α5β1 integrin. Dual regulation of eosinophil priming may prevent inappropriate activation of eosinophils in the circulation.
C-Reactive Protein Induces Signaling Through FcγRIIa on HL-60 Granulocytes
Authors: Chi Maoyen , Tridandapani Susheela , Zhong Wangjian , Coggeshall K. Mark , Mortensen Richard F.
Published: April 2014

Human C-reactive protein (CRP) at acute phase levels of 10–200 μg/ml triggered the phosphorylation of FcγRIIa, Syk kinase, and phospholipase Cγ2 in granulocytic HL-60 cells. CRP also stimulated translocation to the membrane of both phospholipase Cγ2 and phosphatidylinositol-3-kinase. The signaling response triggered by CRP was a rapid, early event with kinetics similar to the response elicited by human IgG. Both soluble-aggregated CRP and monomeric CRP cross-linked FcγRII to generate a signal of the same intensity. The results are consistent with signaling through the intrinsic immunoreceptor tyrosine-based activation motif of the cytoplasmic domain of FcγRIIa, the major CRP-receptor on monocytes and neutrophils that is responsible for CRP-mediated phagocytosis. The signaling events driven by CRP have the potential to regulate infiltrating neutrophil activities.
Aspirin and Salicylates Inhibit the IL-4- and IL-13-Induced Activation of STAT6
Authors: Perez-G. Moises , Melo Marco , Keegan Achsah D. , Zamorano Jose
Published: April 2014

Allergic diseases, including asthma, represent a major threat to human health. Over the three last decades, their incidence has risen in western countries. Aspirin treatment has been shown to improve allergic diseases, especially asthma, and the decreased use of aspirin has been hypothesized to contribute to the increase in childhood asthma. Because salicylate compounds suppress a number of enzymatic activities, and signaling through IL-4R participates in the development of allergic responses, we tested the effect of salicylates on IL-4 signal transduction. We found that treatment of cell lines and primary cells with aspirin and salicylates, but not acetaminophen, inhibited the activation of STAT6 by IL-4 and IL-13. This effect correlated with the inhibition of IL-4-induced CD23 expression. Although salicylates inhibited the in vivo activation of Janus kinases, their kinase activity was not affected in vitro by salicylates, suggesting that other kinases were involved in IL-4-induced STAT6 activation. Furthermore, we found that an Src kinase was involved in STAT6 activation because 1) Src kinase activity was induced by IL-4, 2) Src kinase activity, but not Janus kinase, was inhibited by salicylates in vitro, 3) cells expressing viral Src had constitutive STAT6 phosphorylation, and 4) cells lacking Src showed low STAT6 phosphorylation in response to IL-4. Because STAT6 activation by IL-4 and IL-13 participates in the development of allergic diseases, our results provide a mechanism to explain the beneficial effects of aspirin and salicylate treatment of these diseases.
Administration of Agonistic Anti-4-1BB Monoclonal Antibody Leads to the Amelioration of Experimental Autoimmune Encephalomyelitis
Authors: Sun Yonglian , Lin Xiaoqi , Chen Helen M. , Wu Qiang , Subudhi Sumit K. , Chen Lieping , Fu Yang-Xin
Published: April 2014

4-1BB, a member of the TNFR superfamily, is a costimulatory receptor primarily expressed on activated T cells. It has been shown that the administration of agonistic anti-4-1BB Abs enhances tumor immunity and allogenic immune responses. Paradoxically, we found that the administration of an agonistic anti-4-1BB mAb (2A) dramatically reduced the incidence and severity of experimental autoimmune encephalomyelitis (EAE). Adoptive transfer of T cells from such treated mice failed to induce EAE, whereas anti-4-1BB treatment following adoptive transfer of encephalitogenic T cells did not prevent EAE pathogenesis. These results suggest that anti-4-1BB treatment during the induction phase inhibits autoreactive T cell immune responses rather than preventing T cell trafficking into the CNS. This was substantiated by the observations that draining lymph node cells from anti-4-1BB-treated mice failed to respond to Ag stimulation in vitro. In addition, we found that such treatment initially promotes the activation and proliferation of Ag-specific CD4+ T cells but subsequently increases their probability of undergoing activation-induced cell death, thereby inhibiting effector T cell responses. More importantly, 2A treatment also inhibits the relapse of EAE in a clinically relevant murine model of multiple sclerosis. This study indicates that the agonistic Ab against 4-1BB can potentially be used as a novel immunotherapeutic agent for treating autoimmune diseases.
In Situ β Cell Death Promotes Priming of Diabetogenic CD8 T Lymphocytes
Authors: Zhang Yiqun , O’Brien Bronwyn , Trudeau Jacqueline , Tan Rusung , Santamaria Pere , Dutz Jan P.
Published: April 2014

CTLs are important mediators of pancreatic β cell destruction in the nonobese diabetic mouse model of type 1 diabetes. Cross-presentation of Ag is one means of priming CTLs. The death of Ag-bearing cells has been implicated in facilitating this mode of priming. The role of β cell death in facilitating the onset of spontaneous autoimmune diabetes is unknown. Here, we used an adoptive transfer system to determine the time course of islet-derived Ag presentation to naive β cell-specific CD8 T cells in nonobese diabetic mice and to test the hypothesis that β cell death enhances the presentation of β cell autoantigen. We have determined that β cell death enhances autoantigen presentation. Priming of diabetogenic CD8 T cells in the pancreatic lymph nodes was negligible before 4 wk, progressively increased until 8 wk of age, and was not influenced by gender. Administration of multiple low doses of the β cell toxin streptozotocin augmented in situ β cell apoptosis and accelerated the onset and magnitude of autoantigen presentation to naive CD8 T cells. Increasing doses of streptozotocin resulted in both increased pancreatic β cell death and significantly enhanced T cell priming. These results indicate that in situ β cell death facilitates autoantigen-specific CD8 T cell priming and can contribute to both the initiation and the ongoing amplification of an autoimmune response.
Selective Decrease in Circulating Vα24+Vβ11+ NKT Cells During HIV Type 1 Infection
Authors: van der Vliet Hans J. J. , von Blomberg B. Mary E. , Hazenberg Mette D. , Nishi Nobusuke , Otto Sigrid A. , van Benthem Birgit H. , Prins Maria , Claessen Frans A. , van den Eertwegh Alfons J. M. , Giaccone Giuseppe , Miedema Frank , Scheper Rik J. , Pinedo Herbert M.
Published: April 2014

CD1d-restricted NKT cells express an invariant TCR and have been demonstrated to play an important regulatory role in a variety of immune responses. Invariant NKT cells down-regulate autoimmune responses by production of type 2 cytokines and can initiate antitumor and antimicrobial immune responses by production of type 1 cytokines. Although defects in the (invariant) Vα24+Vβ11+ NKT cell population have been observed in patients with cancer and autoimmune diseases, little is known regarding the protective role of Vα24+Vβ11+ NKT cells in human infectious disease. In a cross-sectional study in HIV-1-infected individuals, we found circulating numbers of Vα24+Vβ11+ NKT cells to be reduced, independent of CD4+ T cell counts, CD4:CD8 ratios, and viral load. Because a small minority of Vα24+Vβ11+ NKT cells of healthy donors expressed HIV-1 (co)receptors and the vast majority of Vα24+Vβ11+ NKT cells in HIV-1-infected individuals expressed the Fas receptor, the depletion was more likely due to Fas-mediated apoptosis than to preferential infection of Vα24+Vβ11+ NKT cells by HIV-1. A longitudinal cohort study, in which patients were analyzed before seroconversion and 1 and 5 years after seroconversion, demonstrated that a large proportion of the depletion occurred within the first year postseroconversion. In this longitudinal study no evidence was found to support an important role of Vα24+Vβ11+ NKT cells in determining the rate of progression during HIV-1 infection.
Cutting Edge: Compartmentalization of Th1-Like Noninvariant CD1d-Reactive T Cells in Hepatitis C Virus-Infected Liver
Authors: Exley Mark A. , He Qi , Cheng Olivia , Wang Ruo-Jie , Cheney Catherine P. , Balk Steven P. , Koziel Margaret J.
Published: April 2014

Murine intrahepatic lymphocytes (IHL) are dominated by invariant TCR α-chain expressing CD1d-reactive NKT cells, which can cause model hepatitis. Invariant NKT (CD56+/−CD161+) and recently identified noninvariant CD1d-reactive T cells rapidly produce large amounts of IL-4 and/or IFN-γ and can regulate Th1/Th2 responses. Human liver contains large numbers of CD56+ NKT cells but few invariant NKT. Compared with matched peripheral blood T cell lines, primary IHL lines from patients with chronic hepatitis C had high levels of CD161 and CD1d reactivity, but the invariant TCR was rare. CD1d-reactive IHL were strikingly Th1 biased. IHL also demonstrated CD1d-specific cytotoxic activity. Hepatocytes and other liver cells express CD1d. These results identify a novel population of human T cells that could contribute to destructive as well as protective immune responses in the liver. CD1d-reactive T cells may have distinct roles in different tissues.
Cutting Edge: Immune Stimulation by Neisserial Porins Is Toll-Like Receptor 2 and MyD88 Dependent
Authors: Massari Paola , Henneke Philipp , Ho Yu , Latz Eicke , Golenbock Douglas T. , Wetzler Lee M.
Published: April 2014

The immunopotentiating activity of neisserial porins, the major outer membrane protein of the pathogenic Neisseria, is mediated by its ability to stimulate B cells and up-regulate the surface expression of B7-2. This ability is dependent on MyD88 and Toll-like receptor (TLR)2 expression, as demonstrated by a lack of a response by B cells from MyD88 or TLR2 knockout mice to the porins. Using previously described TLR2-dependent reporter constructs, these results were confirmed and were shown to be due to induction of NF-κB nuclear translocation. This is the first demonstration of known vaccine adjuvant to stimulate immune cells via TLR2.
Cutting Edge: Tapasin Is Retained in the Endoplasmic Reticulum by Dynamic Clustering and Exclusion from Endoplasmic Reticulum Exit Sites
Authors: Pentcheva Tsvetelina , Spiliotis Elias T. , Edidin Michael
Published: April 2014

Tapasin retains empty or suboptimally loaded MHC class I molecules in the endoplasmic reticulum (ER). However, the molecular mechanism of this process and how tapasin itself is retained in the ER are unknown. These questions were addressed by tagging tapasin with the cyan fluorescent protein or yellow fluorescent protein (YFP) and probing the distribution and mobility of the tagged proteins. YFP-tapasin molecules were functional and could be isolated in association with TAP, as reported for native tapasin. YFP-tapasin was excluded from ER exit sites even after accumulation of secretory cargo due to disrupted anterograde traffic. Almost all tapasin molecules were clustered, and these clusters diffused freely in the ER. Tapasin oligomers appear to be retained by the failure of the export machinery to recognize them as cargo.
Cutting Edge: The Toll Pathway Is Required for Resistance to Gram-Positive Bacterial Infections in Drosophila
Authors: Rutschmann Sophie , Kilinc Ahmet , Ferrandon Dominique
Published: April 2014

In Drosophila, the response against various microorganisms involves different recognition and signaling pathways, as well as distinct antimicrobial effectors. On the one hand, the immune deficiency pathway regulates the expression of antimicrobial peptides that are active against Gram-negative bacteria. On the other hand, the Toll pathway is involved in the defense against filamentous fungi and controls the expression of antifungal peptide genes. The gene coding for the only known peptide with high activity against Gram-positive bacteria, Defensin, is regulated by both pathways. So far, survival experiments to Gram-positive bacteria have been performed with Micrococcus luteus and have failed to reveal the involvement of one or the other pathway in host defense against such infections. In this study, we report that the Toll pathway, but not that of immune deficiency, is required for resistance to other Gram-positive bacteria and that this response does not involve Defensin.
Cutting Edge: A Critical Role for IL-10 in Induction of Nasal Tolerance in Experimental Autoimmune Myocarditis
Authors: Kaya Ziya , Dohmen K. Malte , Wang Yan , Schlichting Jens , Afanasyeva Marina , Leuschner Florian , Rose Noel R.
Published: April 2014

Appropriate treatment of autoimmune myocarditis following virus infection remains a major clinical problem. Induction of nasal tolerance may provide a new approach to treatment. However, the exact mechanism of nasal tolerance is unknown. To assess the mechanism of nasal tolerance, we examined the role of IL-10 in the induction and suppression of autoimmune myocarditis. First we showed that blocking IL-10 concurrent with nasal administration of Ag abolished the disease-suppressing effect of nasal tolerization. It also led to increased cardiac myosin-specific IL-1 and TNF-α production. Then we demonstrated that blocking IL-10 during the effector phase increased not only the incidence and severity of disease but also Ag-specific IL-2, IL-4, and TNF-α production as well as cardiac myosin-specific IgG1 and IgG2b production, whereas blocking IL-10 during the induction phase had no effect. This study implicates IL-10 in the induction of nasal tolerance and in limiting inflammation later during the disease process.
Differential SLP-76 Expression and TCR-Mediated Signaling in Effector and Memory CD4 T Cells
Authors: Hussain S. Farzana , Anderson Charles F. , Farber Donna L.
Published: April 2014

We present in this study novel findings on TCR-mediated signaling in naive, effector, and memory CD4 T cells that identify critical biochemical markers to distinguish these subsets. We demonstrate that relative to naive CD4 T cells, memory CD4 T cells exhibit a profound decrease in expression of the linker/adapter molecule SLP-76, while effector T cells express normal to elevated levels of SLP-76. The reduced level of SLP-76 is memory CD4 T cells is coincident with reduced phosphorylation overall, yet the residual SLP-76 couples to a subset of TCR-associated linker molecules, leading to downstream mitogen-activated protein (MAP) kinase activation. By contrast, effector CD4 T cells strongly phosphorylate SLP-76, linker for activation of T cells, and additional Grb2-coupled proteins, exhibit increased associations of SLP-76 to phosphorylated linkers, and hyperphosphorylate downstream Erk1/2 MAP kinases. Our results suggest distinct coupling of signaling intermediates to the TCR in naive, effector, and memory CD4 T cells. Whereas effector CD4 T cells amplify existing TCR signaling events accounting for rapid effector responses, memory T cells engage fewer signaling intermediates to efficiently link TCR triggering directly to downstream MAP kinase activation.
L-Selectin-Dependent Lymphoid Occupancy Is Required to Induce Alloantigen-Specific Tolerance
Authors: Bai Yalai , Liu Jianhua , Wang Yinong , Honig Shaun , Qin Lihui , Boros Peter , Bromberg Jonathan S.
Published: April 2014

Maneuvers that interfere with signals 1, 2, 3, or Ag processing can result in indefinite allograft survival. However, they are not applicable to all tissues, strains, or species, suggesting that there are additional levels of immune regulation. We hypothesized that secondary lymphoid organs are important for interactions among lymphocytes, alloantigen, and immunosuppressants that lead to tolerance. To explore this, cardiac allografts were performed with a tolerogenic immunosuppressive regimen. Concurrent administration of anti-L-selectin (CD62L) Ab, which prevents lymph node homing, prevents indefinite allograft survival and tolerance. Anti-CD62L Ab is not costimulatory, and Fab and F(ab′)2 anti-CD62L have similar activities. Flow cytometry and histologic examination show that Ab shifts T cells away from lymph nodes and into spleen, peripheral blood, and graft. Tolerance is not induced in CD62L−/− mice, and adoptive transfer of CD62L−/−, but not CD62L+/+, T cells prevents tolerization in wild-type recipients. FTY720, an immunosuppressant that promotes chemokine-dependent, but CD62L-independent, lymph node homing, reverses the Ab effect. Blockade of other homing receptors also prevents tolerization. These results indicate that T lymphocytes use CD62L-dependent migration for alloantigen-specific tolerance, and suggest that lymph nodes or other lymphoid tissues are an important site for peripheral tolerization to alloantigen.
Preferential Th1 Immune Response in Invariant Chain-Deficient Mice
Authors: Topilski Ian , Harmelin Alon , Flavell Richard A. , Levo Yoram , Shachar Idit
Published: April 2014

MHC class II molecules associate with the invariant chain (Ii) molecule during biosynthesis. Ii facilitates the folding of class II molecules, interferes with their peptide association, and is involved in MHC class II transport. In this study, we have investigated the in vitro and in vivo immune response of Ii-deficient mice (Ii−/−). Our results have demonstrated that CD4+ T cells from Ii−/− mice proliferate normally in vitro after in vivo immunization with protein Ags. However, cytokine secretion profiles of Ag-primed CD4+ T cells from Ii−/− mice differ from CD4+ T cells from wild-type mice. Whereas cells from wild-type mice secrete IFN-γ and IL-4, cells from Ii−/− mice secrete mostly IFN-γ. Moreover, Ii−/− mice exhibit a normal Th1 response in the delayed-type hypersensitivity and trinitrobenzene sulfonic acid colitis models; however, these mice lack an in vivo Th2 response, as demonstrated in the asthma model. Therefore, we suggest that defective Ag presentation in Ii−/− mice leads selectively to a Th1 effector response.
Vascular Endothelial-Junctional Adhesion Molecule (VE-JAM)/JAM 2 Interacts with T, NK, and Dendritic Cells Through JAM 3
Authors: Liang Tony W. , Chiu Henry H. , Gurney Austin , Sidle Aiko , Tumas Daniel B. , Schow Peter , Foster Jessica , Klassen Toni , Dennis Kathryn , DeMarco Richard A. , Pham Thinh , Frantz Gretchen , Fong Sherman
Published: April 2014

Screening expressed sequence tag databases for endothelial-specific homologs to human junctional adhesion molecule (JAM) and A33-Ag, we identified a protein of 298 aa that represents the recently described vascular endothelial-JAM (VE-JAM)/JAM 2. We confirmed VE-JAM/JAM 2 expression to be restricted to the high endothelial venule of tonsil and lymph nodes, and we further expanded the localization to the endothelium of arterioles in and around inflammatory and tumor foci. In our functional characterizations of VE-JAM/JAM 2, we discovered that it can function as an adhesive ligand for the T cell line J45 and can interact with GM-CSF/IL-4-derived peripheral blood dendritic cells, circulating CD56+ NK cells, circulating CD56+CD3+ NK/T cells, and circulating CD56+CD3+CD8+ cytolytic T cells. In the course of our studies, we also isolated and characterized the functional VE-JAM/JAM 2 receptor, which, upon cloning, turned out to be a submitted sequence representing JAM 3 (accession number NP 113658). With these understandings, we have characterized a protein-interacting pair that can be important in the role of T, NK, and dendritic cell trafficking and inflammation.
Quantitative and Qualitative Adjustment of Thymic T Cell Production by Clonal Expansion of Premigrant Thymocytes
Authors: Le Campion Armelle , Lucas Bruno , Dautigny Nicole , Léaument Sandrine , Vasseur Florence , Pénit Claude
Published: April 2014

In normal mice, single-positive thymocytes proliferate before being exported into the peripheral T cell pool. We measured the in vivo proliferation rates of mature thymocytes in several TCR transgenic mice. Different monoclonal TCR transgenic single-positive thymocytes proliferated at different rates in a given MHC context. Conversely, mature thymocytes expressing a given TCR, generated in mice of different MHC haplotypes, also showed different rates of proliferation. In p59fyn-deficient mice, the proliferation rate of mature thymocytes was diminished. Thus, premigrant thymocyte expansion is TCR mediated and depends on TCR affinity for self peptide/MHC ligands. In addition, we show that mature thymocyte expansion is clonotypic, increases the daily thymic T cell output, and modifies the TCR repertoire of newly produced T cells.
Minor Histocompatibility Antigen-Specific MHC-Restricted CD8 T Cell Responses Elicited by Heat Shock Proteins
Authors: Robert Jacques , Gantress Jennifer , Rau Laura , Bell Alisa , Cohen Nicholas
Published: April 2014

In mammals, the heat shock proteins (HSP) gp96 and hsp70 elicit potent specific MHC class I-restricted CD8+ T cell (CTL) response to exogenous peptides they chaperone. We show in this study that in the adult frog Xenopus, a species whose common ancestors with mammals date back 300 million years, both hsp70 and gp96 generate an adaptive specific cellular immune response against chaperoned minor histocompatibility antigenic peptides that effects an accelerated rejection of minor histocompatibility-locus disparate skin grafts in vivo and an MHC-specific CD8+ cytotoxic T cell response in vitro. In naturally class I-deficient but immunocompetent Xenopus larvae, gp96 also generates an antitumor immune response that is independent of chaperoned peptides (i.e., gp96 purified from normal tissue also generates a significant antitumor response); this suggests a prominent contribution of an innate type of response in the absence of MHC class I Ags.
Microbial Compounds Selectively Induce Th1 Cell-Promoting or Th2 Cell-Promoting Dendritic Cells In Vitro with Diverse Th Cell-Polarizing Signals
Authors: de Jong Esther C. , Vieira Pedro L. , Kalinski Pawel , Schuitemaker Joost H. N. , Tanaka Yuetsu , Wierenga Eddy A. , Yazdanbakhsh Maria , Kapsenberg Martien L.
Published: April 2014

Upon microbial infection, specific Th1 or Th2 responses develop depending on the type of microbe. Here, we demonstrate that different microbial compounds polarize the maturation of human myeloid dendritic cells (DCs) into stably committed Th1 cell-promoting (DC1) or Th2 cell-promoting (DC2) effector DCs that polarize Th cells via different mechanisms. Protein extract derived from the helminth Schistosoma mansoni induced the development of DC2s that promote the development of Th2 cells via the enhanced expression of OX40 ligand. Likewise, toxin from the extracellular bacterium Vibrio cholerae induced development of DC2s as well, however, via an OX40 ligand-independent, still unknown mechanism. In contrast, toxin from the intracellular bacterium Bordetella pertussis induced the development of DC1s with enhanced IL-12 production, which promotes a Th1 cell development. Poly(I:C) (dsRNA, mimic for virus) induced the development of extremely potent Th1-inducing DC1, surprisingly, without an enhanced IL-12 production. The obtained DC1s and DC2s are genuine effector cells that stably express Th cell-polarizing factors and are unresponsive to further modulation. The data suggest that the molecular basis of Th1/Th2 polarization via DCs is unexpectedly diverse and is adapted to the nature of the microbial compounds.
Repeated Antigen Exposure Is Necessary for the Differentiation, But Not the Initial Proliferation, of Naive CD4+ T Cells
Authors: Bajénoff Marc , Wurtz Olivier , Guerder Sylvie
Published: April 2014

The mechanisms that regulate CD4+ T cells responses in vivo are still poorly understood. We show here that initial Ag stimulation induces in CD4+ T cells a program of proliferation that can develop, for at least seven cycles of division, in the absence of subsequent Ag or cytokine requirement. Thereafter, proliferation stops but can be reinitiated by novel Ag stimulation. This initial Ag stimulation does not however suffice to induce the differentiation of naive CD4+ T cells into effector Th1 cells which requires multiple contacts with Ag-loaded APC. Thus, recurrent exposure to both Ag and polarizing cytokines appears to be essential for the differentiation of IFN-γ-producing cells. Ag and cytokine availability therefore greatly limits the differentiation, but not the initial proliferation, of CD4+ T cells into IFN-γ-producing cells.
Cholera Toxin B Pretreatment of Macrophages and Monocytes Diminishes Their Proinflammatory Responsiveness to Lipopolysaccharide
Authors: Burkart Volker , Kim Yoong-Eun , Hartmann Bettina , Ghiea Iona , Syldath Ulrike , Kauer Manfred , Fingberg Waltraud , Hanifi-Moghaddam Pejman , Müller Sylvia , Kolb Hubert
Published: April 2014

The cholera toxin B chain (CTB) has been reported to suppress T cell-dependent autoimmune diseases and to potentiate tolerance of the adaptive immune system. We have analyzed the effects of CTB on macrophages in vitro and have found that preincubation with CTB (10 μg/ml) suppresses the proinflammatory reaction to LPS challenge, as demonstrated by suppressed production of TNF-α, IL-6, IL-12(p70), and NO (p < 0.01) in cells of macrophage lines. Pre-exposure to CTB also suppresses LPS-induced TNF-α and IL-12(p70) formation in human PBMC. Both native and recombinant CTB exhibited suppressive activity, which was shared by intact cholera toxin. In cells of the human monocyte line Mono Mac 6, exposure to CTB failed to suppress the production of IL-10 in response to LPS. Control experiments excluded a role of possible contamination of CTB by endotoxin or intact cholera toxin. The suppression of TNF-α production occurred at the level of mRNA formation. Tolerance induction by CTB was dose and time dependent. The suppression of TNF-α and IL-6 production could be counteracted by the addition of Abs to IL-10 and TGF-β. IFN-γ also antagonized the actions of CTB on macrophages. In contrast to desensitization by low doses of LPS, tolerance induction by CTB occurred silently, i.e., in the absence of a measurable proinflammatory response. These findings identify immune-deviating properties of CTB at the level of innate immune cells and may be relevant to the use of CTB in modulating immune-mediated diseases.
In Vivo Dehydroepiandrosterone Restores Age-Associated Defects in the Protein Kinase C Signal Transduction Pathway and Related Functional Responses
Authors: Corsini Emanuela , Lucchi Laura , Meroni Massimo , Racchi Marco , Solerte Bruno , Fioravanti Marisa , Viviani Barbara , Marinovich Marina , Govoni Stefano , Galli Corrado L.
Published: April 2014

Elderly subjects are at increased risk of pneumonia, influenza, and tuberculosis. Besides the known age-related decrease in mechanisms for mechanical clearance of the lungs, impaired alveolar macrophage function contributes to the increased risk of illness in the elderly. We have previously shown that age-induced macrophage immunodeficiencies are associated with a defective system for anchoring protein kinase C. Castration of young male rats produces effects on alveolar macrophages similar to those of aging, suggesting a relationship between circulating sex hormones, particularly androgens, and the decreases in the receptor for activated C kinase (RACK-1) and macrophage function observed. The aging process in humans and rats is associated with a decline in the plasma concentrations of dehydroepiandrosterone (DHEA) and its sulfate, among other steroid hormones. We report here that in vitro and in vivo administration of DHEA to rats restores the age-decreased level of RACK-1 and the LPS-stimulated production of TNF-α in alveolar macrophages. DHEA in vivo also restores age-decreased spleen mitogenic responses and the level of RACK-1 expression. These findings suggest that the age-related loss in immunological responses, linked to defective pathways of signal transduction, are partially under hormonal control and can be restored by appropriate replacement therapy.