bluuebunny/crossref_metadata_2025 huggingface dataset:
Spleen Tyrosine Kinase (Syk), a Novel Target of Curcumin, Is Required for B Lymphoma Growth
Authors: Gururajan Murali , Dasu Trivikram , Shahidain Seif , Jennings C. Darrell , Robertson Darrell A. , Rangnekar Vivek M. , Bondada Subbarao
Published: April 2014

Curcumin (diferuloylmethane), a component of dietary spice turmeric (Curcuma longa), has been shown in recent studies to have therapeutic potential in the treatment of cancer, diabetes, arthritis, and osteoporosis. We investigated the ability of curcumin to modulate the growth of B lymphomas. Curcumin inhibited the growth of both murine and human B lymphoma in vitro and murine B lymphoma in vivo. We also demonstrate that curcumin-mediated growth inhibition of B lymphoma is through inhibition of the survival kinase Akt and its key target Bad. However, in vitro kinase assays show that Akt is not a direct target of curcumin. We identified a novel target for curcumin in B lymphoma viz spleen tyrosine kinase (Syk). Syk is constitutively activated in primary tumors and B lymphoma cell lines and curcumin down-modulates Syk activity accompanied by down-regulation of Akt activation. Moreover, we show that overexpression of Akt, a target of Syk, or Bcl-xL, a target of Akt can overcome curcumin-induced apoptosis of B lymphoma cells. These observations suggest a novel growth promoting role for Syk in lymphoma cells.
Feedback Regulation of Murine Autoimmunity via Dominant Anti-Inflammatory Effects of Interferon γ
Authors: Minguela Alfredo , Pastor Silvia , Mi Wentao , Richardson James A. , Ward E. Sally
Published: April 2014

There is a paucity of knowledge concerning the immunologic sequelae that culminate in overt autoimmunity. In the present study, we have analyzed the factors that lead to disease in the model of autoimmunity, murine experimental autoimmune encephalomyelitis (EAE). EAE in H-2u mice involves autoreactive CD4+ T cells that are induced by immunization with the immunodominant N-terminal epitope of myelin basic protein. The affinity of this epitope for I-Au can be increased by substituting lysine at position 4 with tyrosine, and this can be used to increase the effective Ag dose. Paradoxically, high doses of Ag are poorly encephalitogenic. We have used quantitative analyses to study autoreactive CD4+ T cell responses following immunization of mice with Ag doses that are at the extremes of encephalitogenicity. A dose of autoantigen that is poorly encephalitogenic results in T cell hyperresponsiveness, triggering an anti-inflammatory feedback loop in which IFN-γ plays a pivotal role. Our studies define a regulatory mechanism that serves to limit overly robust T cell responses. This feedback regulation has broad relevance to understanding the factors that determine T cell responsiveness.
Dectin-1 Interaction with Tetraspanin CD37 Inhibits IL-6 Production
Authors: Meyer-Wentrup Friederike , Figdor Carl G. , Ansems Marleen , Brossart Peter , Wright Mark D. , Adema Gosse J. , van Spriel Annemiek B.
Published: April 2014

C-type lectins are pattern-recognition receptors important for pathogen binding and uptake by APCs. Evidence is accumulating that integration of incoming cellular signals in APCs is regulated by grouping of receptors and signaling molecules into organized membrane complexes, such as lipid rafts and tetraspanin microdomains. In this study, we demonstrate that C-type lectin dectin-1 functionally interacts with leukocyte-specific tetraspanin CD37. Dectin-1 and CD37 colocalize on the surface of human APCs. Importantly, macrophages of CD37-deficient (CD37−/−) mice express decreased dectin-1 membrane levels, due to increased dectin-1 internalization. Furthermore, transfection of CD37 into a macrophage cell line elevated endogenous dectin-1 surface expression. Although CD37 deficiency does not affect dectin-1-mediated phagocytosis, we observed a striking 10-fold increase of dectin-1-induced IL-6 production in CD37−/− macrophages compared with wild-type cells, despite reduced dectin-1 cell surface expression. Importantly, the observed increase in IL-6 production was specific for dectin-1, because signaling via other pattern-recognition receptors was unaffected in CD37−/− macrophages and because the dectin-1 ligand curdlan was used. Taken together, these findings show that tetraspanin CD37 is important for dectin-1 stabilization in APC membranes and controls dectin-1-mediated IL-6 production.
Th3 Cells in Peripheral Tolerance. I. Induction of Foxp3-Positive Regulatory T Cells by Th3 Cells Derived from TGF-β T Cell-Transgenic Mice
Authors: Carrier Yijun , Yuan Jing , Kuchroo Vijay K. , Weiner Howard L.
Published: April 2014

TGF-β has been shown to be critical in the generation of CD4+CD25+Foxp3+ regulatory T cells (Tregs). Because Th3 cells produce large amounts of TGF-β, we asked whether induction of Th3 cells in the periphery was a mechanism by which CD4+CD25+ Tregs were induced in the peripheral immune compartment. To address this issue, we generated a TGF-β1-transgenic (Tg) mouse in which TGF-β is linked to the IL-2 promoter and T cells transiently overexpress TGF-β upon TCR stimulation but produce little or no IL-2, IL-4, IL-10, IL-13, or IFN-γ. Naive TGF-β-Tg mice are phenotypically normal with comparable numbers of lymphocytes and thymic-derived Tregs. We found that repeated antigenic stimulation of pathogenic myelin oligodendrocyte glycoprotein (MOG)-specific CD4+CD25− T cells from TGF-β Tg mice crossed to MOG TCR-Tg mice induced Foxp3 expression in both CD25+ and CD25− populations. Both CD25 subsets were anergic and had potent suppressive properties in vitro and in vivo. Furthermore, adoptive transfer of these induced regulatory CD25+/− T cells suppressed experimental autoimmune encephalomyelitis when administrated before disease induction or during ongoing experimental autoimmune encephalomyelitis. The suppressive effect of TGF-β on T cell responses was due to the induction of Tregs and not to the direct inhibition of cell proliferation. The differentiation of Th3 cells in vitro was TGF-β dependent as anti-TGF-β abrogated their development. Thus, Ag-specific TGF-β-producing Th3 cells play a crucial role in inducing and maintaining peripheral tolerance by driving the differentiation of Ag-specific Foxp3+ regulatory cells in the periphery.
IFN-γ Negatively Regulates CpG-Induced IL-10 in Bone Marrow-Derived Dendritic Cells
Authors: Flores Rafael R. , Diggs Kelly A. , Tait Lauren M. , Morel Penelope A.
Published: April 2014

Dendritic cells (DCs) are important players in the regulation of Th1- and Th2-dominated immune responses. In these studies we showed that IFN-γ, the key mediator of Th1 immunity, actively suppressed the production of IL-10 in murine DCs when activated with LPS or CpG. Our analysis revealed that both LPS and CpG induced IL-10 and IL-12 production but that the presence of IFN-γ, in a dose-dependent manner, suppressed the production of IL-10 while enhancing that of IL-12. The observed inhibition of IL-10 production was independent of IL-12. Experiments performed with STAT-1 knockout mice demonstrated that the primary production of IL-12 induced by CpG was STAT-1 dependent, whereas the production of IL-10 was not. This finding was confirmed by the observation that CpG-induced IL-12 production could be inhibited by anti-IFN-β Abs, whereas CpG-induced IL-10 production could not be inhibited. These data also demonstrated that the inhibitory effect of IFN-γ on IL-10 expression was STAT-1 dependent and transcriptionally regulated. Thus, DCs respond to CpG by producing proinflammatory and anti-inflammatory cytokines such as IL-12 and IL-10, respectively, and IFN-γ acts to not only enhance IL-12 but also to inhibit IL-10 production. The current data demonstrate a novel pathway for IFN-γ-mediated immunoregulation and suggest that IFN-γ-dependent suppression of IL-10 production by DCs may be involved in the antagonism between Th1 and Th2 patterns of immune reactivity.
FoxP3+ T Cells Undergo Conventional First Switch to Lymphoid Tissue Homing Receptors in Thymus but Accelerated Second Switch to Nonlymphoid Tissue Homing Receptors in Secondary Lymphoid Tissues
Authors: Lee Jee H. , Kang Seung G. , Kim Chang H.
Published: April 2014

Forkhead box P3 (FoxP3)-positive T cells are a specialized T cell subset for immune regulation and tolerance. We investigated the trafficking receptor switches of FoxP3+ T cells in thymus and secondary lymphoid tissues and the functional consequences of these switches in migration. We found that FoxP3+ T cells undergo two discrete developmental switches in trafficking receptors to migrate from primary to secondary and then to nonlymphoid tissues in a manner similar to conventional CD4+ T cells as well as unique to the FoxP3+ cell lineage. In the thymus, precursors of FoxP3+ cells undergo the first trafficking receptor switch (CCR8/CCR9→CXCR4→CCR7), generating mostly homogeneous CD62L+CCR7+CXCR4lowFoxP3+ T cells. CXCR4 expression is regained in FoxP3+ thymic emigrants in the periphery. Consistent with this switch, recent FoxP3+ thymic emigrants migrate exclusively to secondary lymphoid tissues but poorly to nonlymphoid tissues. The FoxP3+ thymic emigrants undergo the second switch in trafficking receptors for migration to nonlymphoid tissues upon Ag priming. This second switch involves down-regulation of CCR7 and CXCR4 but up-regulation of a number of memory/effector type homing receptors, resulting in generation of heterogeneous FoxP3+ T cell subsets expressing various combinations of trafficking receptors including CCR2, CCR4, CCR6, CCR8, and CCR9. A notable difference between the FoxP3+ and FoxP3− T cell populations is that FoxP3+ T cells undergo the second homing receptor switch at a highly accelerated rate compared with FoxP3− T cells, generating FoxP3+ T cells with unconventionally efficient migratory capacity to major nonlymphoid tissues.
Cutting Edge: Allele-Specific and Peptide-Dependent Interactions between KIR3DL1 and HLA-A and HLA-B
Authors: Thananchai Hathairat , Gillespie Geraldine , Martin Maureen P. , Bashirova Arman , Yawata Nobuyo , Yawata Makoto , Easterbrook Philippa , McVicar Daniel W. , Maenaka Katsumi , Parham Peter , Carrington Mary , Dong Tao , Rowland-Jones Sarah
Published: April 2014

Although it is clear that KIR3DL1 recognizes Bw4+ HLA-B, the role of Bw4+ HLA-A allotypes as KIR3DL1 ligands is controversial. We therefore examined the binding of tetrameric HLA-A and –B complexes, including HLA*2402, a common Bw4+ HLA-A allotype, to KIR3DL1*001, *005, *007, and *1502 allotypes. Only Bw4+ tetramers bound KIR3DL1. Three of four HLA-A*2402 tetramers bound one or more KIR3DL1 allotypes and all four KIR3DL1 allotypes bound to one or more HLA-A*2402 tetramers, but with different binding specificities. Only KIR3DL1*005 bound both HLA-A*2402 and HLA-B*5703 tetramers. HLA-A*2402-expressing target cells were resistant to lysis by NK cells expressing KIR3DL1*001 or *005. This study shows that HLA-A*2402 is a ligand for KIR3DL1 and demonstrates how the binding of KIR3DL1 to Bw4+ ligands depends upon the bound peptide as well as HLA and KIR3DL1 polymorphism.
Loss of Src Homology Region 2 Domain-Containing Protein Tyrosine Phosphatase-1 Increases CD8+ T Cell-APC Conjugate Formation and Is Associated with Enhanced In Vivo CTL Function
Authors: Sathish Jean G. , Dolton Garry , LeRoy Frances G. , Matthews R. James
Published: April 2014

Extensive evidence has been accumulated to implicate the intracellular protein tyrosine phosphatase, Src homology region 2 domain-containing protein tyrosine phosphatase-1 (SHP-1), as a negative regulator of TCR-signaling thresholds. Specifically, T cells from the SHP-1-deficient mouse, motheaten, exhibit a hyperproliferative phenotype when activated by cognate peptide-pulsed APCs. However, the cellular basis for this phenotype has not been fully explained. Using the intracellular fluorescent dye, CFSE, we show that a greater proportion of motheaten vs control naive CD8+ T cells undergo cell division when activated by peptide-pulsed APCs. Furthermore, there is a greater likelihood of TCRs on SHP-1-deficient vs control T cells binding to peptide/MHC ligands on APCs when using TCR down-regulation as an indirect measure of TCR engagement. In addition, T cell-APC conjugate assays provide direct evidence that a greater proportion of SHP-1-deficient T cells are capable of forming stable conjugates with APCs and this may explain, at least in part, their hyperproliferative response to TCR-triggered stimulation. The physiological relevance of the combined in vitro observations is demonstrated by the significantly enhanced in vivo expansion and CTL capacity generated in mice receiving adoptively transferred SHP-1-deficient naive CD8+ T cells when compared with control T cells.
Brahma-Related Gene 1-Dependent STAT3 Recruitment at IL-6-Inducible Genes
Authors: Ni Zuyao , Bremner Rod
Published: April 2014

IL-6 is an immunoregulatory cytokine with multiple functions in hemopoiesis, proliferation, and tumorigenesis. IL-6 triggers phosphorylation, dimerization, and nuclear translocation of STAT3, which binds to target promoters and activates transcription. Brahma-related gene 1 (BRG1), the enzymatic engine of the yeast-mating type-switching and sucrose-nonfermenting chromatin-remodeling complex, is essential for recruitment of STAT1 or STAT1/STAT2-containing complexes to IFN targets. We hypothesized that BRG1 might also be required for STAT3 recruitment. In this study, we show that induction of a subset of human IL-6-responsive genes is BRG1 dependent. BRG1 is constitutively present at these targets and is required for STAT3 recruitment, downstream histone modifications, and IL-6-induced chromatin remodeling. IL-6-induced recruitment of STAT3 to the IFN regulatory factor 1 promoter and subsequent mRNA synthesis is BRG1 dependent, even though IFN-γ-mediated STAT1 recruitment to this locus is BRG1 independent. BRG1 also increased basal expression of IFN-induced transmembrane protein 3 and IFN-γ-induced protein 16, and the basal chromatin accessibility at the promoter of IFN regulatory factor 1. The effect on basal expression was STAT3 independent, as revealed by small interfering RNA knockdown. Together with prior observations, these data reveal that BRG1 has a broad role in mediating STAT accessibility at multiple cytokine-responsive promoters and exposes promoter specific differences in both the effect of BRG1 on basal chromatin accessibility and on access of different STAT proteins to the same target.
Decay-Accelerating Factor Must Bind Both Components of the Complement Alternative Pathway C3 Convertase to Mediate Efficient Decay
Authors: Harris Claire L. , Pettigrew David M. , Lea Susan M. , Morgan B. Paul
Published: April 2014

Decay-accelerating factor (DAF; CD55) inhibits the complement (C) cascade by dissociating the multimolecular C3 convertase enzymes central to amplification. We have previously demonstrated using surface plasmon resonance (Biacore International) that DAF mediates decay of the alternative pathway C3 convertase, C3bBb, but not of the inactive proenzyme, C3bB, and have shown that the major site of interaction is with the larger cleavage subunit factor B (Bb) subunit. In this study, we dissect these interactions and demonstrate that the second short consensus repeat (SCR) domain of DAF (SCR2) interacts only with Bb, whereas SCR4 interacts with C3b. Despite earlier studies that found SCR3 to be critical to DAF activity, we find that SCR3 does not directly interact with either subunit. Furthermore, we demonstrate that properdin, a positive regulator of the alternative pathway, does not directly interact with DAF. Extending from studies of binding to decay-accelerating activity, we show that truncated forms of DAF consisting of SCRs 2 and 3 bind the convertase stably via SCR2-Bb interactions but have little functional activity. In contrast, an SCR34 construct mediates decay acceleration, presumably due to SCR4-C3b interactions demonstrated above, because SCR3 alone has no binding or functional effect. We propose that DAF interacts with C3bBb through major sites in SCR2 and SCR4. Binding to Bb via SCR2 increases avidity of binding, concentrating DAF on the active convertase, whereas more transient interactions through SCR4 with C3b directly mediate decay acceleration. These data provide new insights into the mechanisms involved in C3 convertase decay by DAF.
Critical Residues at the Ly49 Natural Killer Receptor’s Homodimer Interface Determine Functional Recognition of m157, a Mouse Cytomegalovirus MHC Class I-Like Protein
Authors: Kielczewska Agnieszka , Kim Hee-Seo , Lanier Lewis L. , Dimasi Nazzareno , Vidal Silvia M.
Published: April 2014

NK cell function is regulated by Ly49 receptors in mice and killer cell Ig-like receptors in humans. Although inhibitory Ly49 and killer cell Ig-like receptors predominantly ligate classical MHC class I molecules, recent studies suggest that their activating counterparts recognize infection. The quintessential example is resistance to the mouse CMV in C57BL/6 mice, which depends on the functional recognition of m157, a mouse CMV-encoded MHC class I-like molecule, by Ly49H, an activating NK cell receptor. We have taken advantage of the natural variation in closely related members of the Ly49C-like receptors and the availability of Ly49 crystal structures to understand the molecular determinants of the Ly49H-m157 interaction and to identify amino acid residues discriminating between m157 binding and nonbinding receptors. Using a site-directed mutagenesis approach, we have targeted residues conserved in receptors binding to m157 (Ly49H and Ly49I129) but different from receptors lacking m157 recognition (Ly49C, Ly49IB6, and Ly49U). Wild-type and mutant receptors were transfected into reporter cells, and physical binding as well as functional activation by m157 was studied. Our findings suggested that the Ly49 MHC class I contact “site 2,” I226, may not be involved in m157 binding. In contrast, residue Y146 and G151, mapping at the receptor homodimer interface, are likely critical for functional recognition of the m157 glycoprotein. Our combined functional and three-dimensional modeling approach suggested that the architecture of the Ly49H dimer is crucial to accessing m157, but not MHC class I. These results link Ly49 homodimerization variability to the direct recognition of pathogen products.
Distinct and Shared Transcriptomes Are Regulated by Microphthalmia-Associated Transcription Factor Isoforms in Mast Cells
Authors: Shahlaee Amir H. , Brandal Stephanie , Lee Youl-Nam , Jie Chunfa , Takemoto Clifford M.
Published: April 2014

The Microphthalmia-associated transcription factor (Mitf) is an essential basic helix-loop-helix leucine zipper transcription factor for mast cell development. Mice deficient in Mitf harbor a severe mast cell deficiency, and Mitf-mutant mast cells cultured ex vivo display a number of functional defects. Therefore, an understanding of the genetic program regulated by Mitf may provide important insights into mast cell differentiation. Multiple, distinct isoforms of Mitf have been identified in a variety of cell types; we found that Mitf-a, Mitf-e, and Mitf-mc were the major isoforms expressed in mast cells. To determine the physiologic function of Mitf in mast cells, we restored expression of these isoforms in primary mast cells from Mitf−/− mice. We found that these isoforms restored granular morphology and integrin-mediated migration. By microarray analysis, proteases, signaling molecules, cell surface receptor, and transporters comprised the largest groups of genes up-regulated by all isoforms. Furthermore, we found that isoforms also regulated distinct genes sets, suggesting separable biological activities. This work defines the transcriptome regulated by Mitf in mast cells and supports its role as master regulator of mast cell differentiation. Expression of multiple isoforms of this transcription factor may provide for redundancy of biological activities while also allowing diversity of function.
Regulation of Leukocyte Degranulation by cGMP-Dependent Protein Kinase and Phosphoinositide 3-Kinase: Potential Roles in Phosphorylation of Target Membrane SNARE Complex Proteins in Rat Mast Cells
Authors: Nanamori Masakatsu , Chen Jia , Du Xiaoping , Ye Richard D.
Published: April 2014

We examined the roles of cGMP-dependent protein kinase (PKG) and PI3K in degranulation induced by fMLF and by FcεRI cross-linking. In rat basophilic leukemia-2H3 cells expressing formyl peptide receptor, the PKG inhibitors KT5823 and Rp-8-Br-PET-cGMP, as well as the PI3K inhibitor LY294002, reduced agonist-stimulated β-hexosaminidase release in a dose-dependent manner. These inhibitors also abolished vesicular fusion with the plasma membrane, as evidenced by diminished annexin V staining. Agonist-induced degranulation was completely blocked when LY294002 was applied together with one of the PKG inhibitors, suggesting an additive and possibly synergistic effect. In contrast, the PKG inhibitors did not affect fMLF-induced intracellular calcium mobilization and Akt phosphorylation. Likewise, LY294002 did not alter fMLF-induced elevation of intracellular cGMP concentration, and the inhibitory effect of LY294002 was not reversed by a cell-permeable analog of cGMP. Treatment with fMLF induced phosphorylation of soluble N-ethylmaleimide-sensitive factor-attachment protein (SNAP)-23, syntaxins 2, 4, and 6, and Monc18-3. The induced phosphorylation of SNAP-23 and syntaxins 2 and 4 was blocked by Rp-8-Br-PET-cGMP and LY294002. However, LY294002 was less effective in inhibiting Munc18-3 phosphorylation. The induced phosphorylation of syntaxin 6 was not effectively blocked by either Rp-8-Br-PET-cGMP or LY294002. Treatment of human neutrophils with the PKG inhibitors and LY294002 reduced enzyme release from primary, secondary, and tertiary granules. These results suggest that PKG and PI3K are involved in degranulation, possibly through phosphorylation of target membrane SNAP receptor proteins and their binding proteins.
Differential Regulation of Cytokine Release and Leukocyte Migration by Lipopolysaccharide-Stimulated Primary Human Lung Alveolar Type II Epithelial Cells and Macrophages
Authors: Thorley Andrew J. , Ford Paul A. , Giembycz Mark A. , Goldstraw Peter , Young Alan , Tetley Teresa D.
Published: April 2014

Bacterial colonization is a secondary feature of many lung disorders associated with elevated cytokine levels and increased leukocyte recruitment. We hypothesized that, alongside macrophages, the epithelium would be an important source of these mediators. We investigated the effect of LPS (0, 10, 100, and 1000 ng/ml LPS, up to 24 h) on primary human lung macrophages and alveolar type II epithelial cells (ATII; isolated from resected lung tissue). Although macrophages produced higher levels of the cytokines TNF-α and IL-1β (p < 0.0001), ATII cells produced higher levels of chemokines MCP-1, IL-8, and growth-related oncogene α (p < 0.001), in a time- and concentration-dependent manner. Macrophage (but not ATII cell) responses to LPS required activation of ERK1/2 and p38 MAPK signaling cascades; phosphorylated ERK1/2 was constitutively up-regulated in ATII cells. Blocking Abs to TNF-α and IL-1β during LPS exposure showed that ATII cell (not macrophage) MCP-1 release depended on the autocrine effects of IL-1β and TNF-α (p < 0.003, 24 h). ATII cell release of IL-6 depended on autocrine effects of TNF-α (p < 0.006, 24 h). Macrophage IL-6 release was most effectively inhibited when both TNF-α and IL-1β were blocked (p < 0.03, 24 h). Conditioned media from ATII cells stimulated more leukocyte migration in vitro than conditioned media from macrophages (p < 0.0002). These results show differential activation of cytokine and chemokine release by ATII cells and macrophages following LPS exposure. Activated alveolar epithelium is an important source of chemokines that orchestrate leukocyte migration to the peripheral lung; early release of TNF-α and IL-1β by stimulated macrophages may contribute to alveolar epithelial cell activation and chemokine production.
Critical Role of the Fc Receptor γ-Chain on APCs in the Development of Allergen-Induced Airway Hyperresponsiveness and Inflammation
Authors: Kitamura Kenichi , Takeda Katsuyuki , Koya Toshiyuki , Miyahara Nobuaki , Kodama Taku , Dakhama Azzeddine , Takai Toshiyuki , Hirano Atsushi , Tanimoto Mitsune , Harada Mine , Gelfand Erwin W.
Published: April 2014

The FcR common γ-chain (FcRγ) is an essential component of the receptors FcεRI, FcγRI, and FcγRIII, which are expressed on many inflammatory cell types. The role of these receptors in the initiation or maintenance of allergic inflammation has not been well defined. FcRγ-deficient (FcRγ−/−) and control (wild-type (WT)) mice were sensitized and subsequently challenged with OVA. Following sensitization and challenge to OVA, FcRγ-deficient (FcRγ−/−) mice developed comparable levels of IgE and IgG1 as WT mice. However, numbers of eosinophils, levels of IL-5, IL-13, and eotaxin in bronchoalveolar lavage fluid, and mononuclear cell (MNC) proliferative responses to OVA were significantly reduced, as was airway hyperresponsiveness (AHR) to inhaled methacholine. Reconstitution of FcRγ−/− mice with whole spleen MNC from WT mice before sensitization restored development of AHR and the numbers of eosinophils in bronchoalveolar lavage fluid; reconstitution after sensitization but before OVA challenge only partially restored these responses. These responses were also restored when FcRγ−/− mice received T cell-depleted MNC, T and B cell-depleted MNC, or bone marrow-derived dendritic cells before sensitization from FcR+/+ or FcγRIII-deficient but not FcRγ−/− mice. The expression levels of FcγRIV on bone marrow-derived dendritic cells from FcR+/+ mice were found to be low. These results demonstrate that expression of FcRγ, most likely FcγRI, on APCs is important during the sensitization phase for the development of allergic airway inflammation and AHR.
TLR3-Mediated Synthesis and Release of Eotaxin-1/CCL11 from Human Bronchial Smooth Muscle Cells Stimulated with Double-Stranded RNA
Authors: Niimi Kyoko , Asano Koichiro , Shiraishi Yoshiki , Nakajima Takeshi , Wakaki Misa , Kagyo Junko , Takihara Takahisa , Suzuki Yusuke , Fukunaga Koichi , Shiomi Tetsuya , Oguma Tsuyoshi , Sayama Koichi , Yamaguchi Kazuhiro , Natori Yukikazu , Matsumoto Misako , Seya Tsukasa , Yamaya Mutsuo , Ishizaka Akitoshi
Published: April 2014

Respiratory infections with RNA viruses, such as rhinovirus or respiratory syncytial virus, are a major cause of asthma exacerbation, accompanied by enhanced neutrophilic and/or eosinophilic inflammation of the airways. We studied the effects of dsRNA synthesized during RNA virus replication, and of its receptor, TLR3, on the synthesis of eosinophilic chemokines in bronchial smooth muscle cells (BSMC). Synthetic dsRNA, polyinosinic-cystidic acid (poly(I:C)), induced the synthesis of eosinophilic chemokines, eotaxin-1/CCL11 and RANTES/CCL5, from primary cultures of human BSMC, and IL-4 increased synergistically the synthesis of poly(I:C)-induced CCL11. A robust eosinophil chemotactic activity was released from BSMC stimulated with poly(I:C) and IL-4, which was mostly inhibited by preincubation with an anti-CCL11, but not with an anti-CCL5 Ab. Although the immunoreactivity of TLR3 was detectable on the cellular surface of BSMC by flow cytometric analysis, pretreatment with an anti-TLR3-neutralizing Ab failed to block the poly(I:C)-induced synthesis of CCL11. We have determined by confocal laser-scanning microscopy that the immunoreactivity of TLR3 was aggregated intracellularly in poly(I:C)-stimulated BSMC, colocalizing with fluorescein-labeled poly(I:C). The synthesis of CCL11 was prominently inhibited by the transfection of TLR3-specific small interfering RNA or by bafilomycin A1, an endosomal acidification inhibitor, further supporting the essential role played by intracellular TLR3 in the synthesis of poly(I:C)-induced CCL11 in BSMC. In conclusion, these observations suggest that, by activating intracellular TLR3 in BSMC, respiratory RNA virus infections stimulate the production of CCL11 and enhance eosinophilic inflammation of the airways in the Th2-dominant microenvironment.
B Cell Lymphoma 10 Is Essential for FcεR-Mediated Degranulation and IL-6 Production in Mast Cells
Authors: Chen Yuhong , Pappu Bhanu P. , Zeng Hu , Xue Liquan , Morris Stephan W. , Lin Xin , Wen Renren , Wang Demin
Published: April 2014

The adaptor protein B cell lymphoma 10 (Bcl10) plays an essential role in the functions of the AgRs in T and B cells. In this study, we report that Bcl10 also plays an important role in mast cells. Bcl10 is expressed in mast cells. Although Bcl10-deficient mast cells undergo normal development, we demonstrate that Bcl10 is essential for specific functions of FcεR. Although Bcl10-deficient mast cells have normal de novo synthesis and release of the lipid mediator arachidonic acid, the mutant cells possess impaired FcεR-mediated degranulation, indicated by decreased serotonin release, and impaired cytokine production, measured by release of IL-6. In addition, Bcl10-deficient mice display impaired IgE-mediated passive cutaneous anaphylaxis. Moreover, although Bcl10-deficient mast cells have normal FcεR-mediated Ca2+ flux, activation of PI3K, and activation of the three types of MAPKs (ERKs, JNK, and p38), the mutant cells have markedly diminished FcεR-mediated activation of NF-κB and decreased activation of AP-1. Thus, Bcl10 is essential for FcεR-induced activation of AP-1, NF-κB, degranulation, and cytokine production in mast cells.
Protectin D1 Is Generated in Asthma and Dampens Airway Inflammation and Hyperresponsiveness
Authors: Levy Bruce D. , Kohli Payal , Gotlinger Katherine , Haworth Oliver , Hong Song , Kazani Shamsah , Israel Elliot , Haley Kathleen J. , Serhan Charles N.
Published: April 2014

Protectins are newly identified natural chemical mediators that counter leukocyte activation to promote resolution of inflammation. In this study, we provide the first evidence for protectin D1 (PD1, 10R,17S-dihydroxy-docosa-4Z,7Z,11E,13E,15Z,19Z-hexaenoic acid) formation from docosahexaenoic acid in human asthma in vivo and PD1 counterregulatory actions in allergic airway inflammation. PD1 and 17S-hydroxy-docosahexaenoic acid were present in exhaled breath condensates from healthy subjects. Of interest, levels of PD1 were significantly lower in exhaled breath condensates from subjects with asthma exacerbations. PD1 was also present in extracts of murine lungs from both control animals and those sensitized and aerosol challenged with allergen. When PD1 was administered before aeroallergen challenge, airway eosinophil and T lymphocyte recruitment were decreased, as were airway mucus, levels of specific proinflammatory mediators, including IL-13, cysteinyl leukotrienes, and PGD2, and airway hyperresponsiveness to inhaled methacholine. Of interest, PD1 treatment after aeroallergen challenge markedly accelerated the resolution of airway inflammation. Together, these findings provide evidence for endogenous PD1 as a pivotal counterregulatory signal in allergic airway inflammation and point to new therapeutic strategies for modulating inflammation in asthmatic lung.
Sensitivity of NK1.1-Negative NKT Cells to Transgenic BATF Defines a Role for Activator Protein-1 in the Expansion and Maturation of Immature NKT Cells in the Thymus
Authors: Zullo Alfred J. , Benlagha Kamel , Bendelac Albert , Taparowsky Elizabeth J.
Published: April 2014

NKT cells are glycolipid-reactive lymphocytes that express markers and perform functions common to both T lymphocytes and NK cells. Although the genetic events controlling conventional T cell development are well defined, the transcription factors and genetic programs regulating NKT cell development are only beginning to be elucidated. Previously, we described the NKT cell-deficient phenotype of transgenic (Tg) mice constitutively expressing B cell-activating transcription factor (BATF), a basic leucine zipper protein and inhibitor of AP-1. In this study, we show that Tg BATF targets the majority of Vα14Jα281 (Vα14i7) NKT cells, regardless of CD4 expression and Vβ gene usage. The residual NKT cells in the thymus of BATF-Tg mice are CD44+, yet are slow to display the NK1.1 marker characteristic of mature cells. As a population, BATF-expressing NKT cells are TCRβ/CD3εlow, but express normal levels of CD69, suggesting a failure to expand appropriately following selection. Consistent with the sensitivity of NKT cells to BATF-induced changes in AP-1 activity, we detect a full complement of AP-1 basic leucine zipper proteins in wild-type NKT cells isolated from the thymus, spleen, and liver, and show that AP-1 DNA-binding activity and cytokine gene transcription are induced in NKT cells within a few hours of glycolipid Ag exposure. This study is the first to characterize AP-1 activity in NKT cells and implicates the integrity of this transcription factor complex in developmental events essential to the establishment of this unique T cell subset in the thymus.
Granulysin-Mediated Tumor Rejection in Transgenic Mice
Authors: Huang Lisa P. , Lyu Shu-Chen , Clayberger Carol , Krensky Alan M.
Published: April 2014

Granulysin (GNLY) is a cytolytic molecule expressed by human CTL and NK cells with activity against a variety of tumors and microbes, including Mycobacterium tuberculosis. Although the molecular mechanism of GNLY-induced apoptosis of Jurkat T cells is well defined in vitro, no direct evidence for its in vivo effects has been demonstrated. Because there is no murine homologue of GNLY, we generated mice expressing GNLY using a bacterial artificial chromosome containing the human GNLY gene and its 5′ and 3′ flanking regions. GNLY is expressed in leukocytes from transgenic mice with similar kinetics as in PBMC from humans: GNLY is constitutively expressed in NK cells and, following stimulation through the TCR, appears in T lymphocytes 8–10 days after activation. Both forms of GNLY (9 and 15 kDa) are produced by activated T cells, whereas the 15-kDa form predominates in freshly isolated NK cells from transgenic animals. GNLY mRNA is highest in spleen, with detectable expression in thymus and lungs, and minimal expression in heart, kidney, liver, muscle, intestine, and brain. Allospecific cell lines generated from GNLY transgenic animals showed enhanced killing of target cells. In vivo effects of GNLY were evaluated using the syngeneic T lymphoma tumor C6VL. GNLY transgenic mice survived significantly longer than nontransgenic littermates in response to a lethal tumor challenge. These findings demonstrate for the first time an in vivo effect of GNLY and suggest that GNLY may prove a useful therapeutic modality for the treatment of cancer.
Tumor-Primed Human Natural Killer Cells Lyse NK-Resistant Tumor Targets: Evidence of a Two-Stage Process in Resting NK Cell Activation
Authors: North Janet , Bakhsh Ismail , Marden Chloe , Pittman Hanna , Addison Elena , Navarrete Cristina , Anderson Robert , Lowdell Mark W.
Published: April 2014

NK cells are defined as those cells that lyse tumor cells without priming. In this study, we show that the preincubation of resting human NK cells with the leukemia cell CTV-1 primes NK cells to lyse NK-resistant cell lines, primary leukemias, and solid tumors even when HLA-matched, allogeneic or autologous. The primed NK cells remained nonresponsive to HLA-C matched and mismatched normal mononuclear cells from multiple donors. CD69, a known NK trigger receptor, was shown to be the predominant trigger on the tumor-primed NK cells because lysis was blocked with the rCD69 protein. The lack of lytic activity against normal hemopoietic cells implied that the ligand for CD69 is tumor restricted, and this was confirmed by experiments using fluorochrome labeled rCD69. It has been recently shown that resting NK cells require prior stimulation with IL-2 before triggering by all known NK-triggering ligands. In this study, we show that a tumor cell can provide the NK priming signal independently of IL-2. These data provide evidence for two NK evasion strategies for tumor cells, namely the prevention of priming (type1 evasion) and failure to trigger (type 2 evasion). Most NK-resistant cell lines are type 1 and fail to prime resting NK cells but are lysed by IL-2-primed NK cells. In contrast, CTV-1 cells prime resting NK cells but fail to trigger (type 2), and coincubation with CTV-1 primes for triggering by type 1 NK-resistant tumor cells. These tumor-activated NK cells lyse a broad spectrum of tumor cells with a degree of specificity never previously reported.
Distinct Effector Cytokine Profiles of Memory and Naive Human B Cell Subsets and Implication in Multiple Sclerosis
Authors: Duddy Martin , Niino Masaaki , Adatia Femina , Hebert Sherry , Freedman Mark , Atkins Harry , Kim Ho Jin , Bar-Or Amit
Published: April 2014

Although recent animal studies have fuelled growing interest in Ab-independent functions of B cells, relatively little is known about how human B cells and their subsets may contribute to the regulation of immune responses in either health or disease. In this study, we first confirm that effector cytokine production by normal human B cells is context dependent and demonstrate that this involves the reciprocal regulation of proinflammatory and anti-inflammatory cytokines. We further report that this cytokine network is dysregulated in patients with the autoimmune disease multiple sclerosis, whose B cells exhibit a decreased average production of the down-regulatory cytokine IL-10. Treatment with the approved chemotherapeutic agent mitoxantrone reciprocally modulated B cell proinflammatory and anti-inflammatory cytokines, establishing that the B cell cytokine network can be targeted in vivo. Prospective studies of human B cells reconstituting following in vivo depletion suggested that different B cell subsets produced distinct effector cytokines. We confirmed in normal human B cell subsets that IL-10 is produced almost exclusively by naive B cells while the proinflammatory cytokines lymphotoxin and TNF-α are largely produced by memory B cells. These results point to an in vivo switch in the cytokine “program” of human B cells transitioning from the naive pool to the memory pool. We propose a model that ascribes distinct and proactive roles to memory and naive human B cell subsets in the regulation of memory immune responses and in autoimmunity. Our findings are of particular relevance at a time when B cell directed therapies are being applied to clinical trials of several autoimmune diseases.
Salmonella Induces a Switched Antibody Response without Germinal Centers That Impedes the Extracellular Spread of Infection
Authors: Cunningham Adam F. , Gaspal Fabrina , Serre Karine , Mohr Elodie , Henderson Ian R. , Scott-Tucker Anthony , Kenny Sinead M. , Khan Mahmood , Toellner Kai-Michael , Lane Peter J. L. , MacLennan Ian C. M.
Published: April 2014

T-dependent Ab responses are characterized by parallel extrafollicular plasmablast growth and germinal center (GC) formation. This study identifies that, in mice, the Ab response against Salmonella is novel in its kinetics and its regulation. It demonstrates that viable, attenuated Salmonella induce a massive early T-dependent extrafollicular response, whereas GC formation is delayed until 1 mo after infection. The extrafollicular Ab response with switching to IgG2c, the IgG2a equivalent in C57BL/6 mice, is well established by day 3 and persists through 5 wk. Switching is strongly T dependent, and the outer membrane proteins are shown to be major targets of the early switched IgG2c response, whereas flagellin and LPS are not. GC responses are associated with affinity maturation of IgG2c, and their induction is associated with bacterial burden because GC could be induced earlier by treating with antibiotics. Clearance of these bacteria is not a consequence of high-affinity Ab production, for clearance occurs equally in CD154-deficient mice, which do not develop GC, and wild-type mice. Nevertheless, transferred low- and high-affinity IgG2c and less efficiently IgM were shown to impede Salmonella colonization of splenic macrophages. Furthermore, Ab induced during the infection markedly reduces bacteremia. Thus, although Ab does not prevent the progress of established splenic infection, it can prevent primary infection and impedes secondary hemogenous spread of the disease. These results may explain why attenuated Salmonella-induced B cell responses are protective in secondary, but not primary infections.
Antibody Repertoire Development in Fetal and Neonatal Piglets: XIX. Undiversified B Cells with Hydrophobic HCDR3s Preferentially Proliferate in the Porcine Reproductive and Respiratory Syndrome
Authors: Butler John E. , Lemke Caitlin D. , Weber Patrick , Sinkora Marek , Lager Kelly M.
Published: April 2014

Porcine respiratory and reproductive syndrome virus (PRRSV) causes an extraordinary increase in the proportion of B cells resulting in lymphoid hyperplasia, hypergammaglobulinemia, and autoimmunity in neonatal piglets. Spectratypic analysis of B cells from neonatal isolator piglets show a non-Gaussian pattern with preferential expansion of clones bearing certain H chain third complementary region (HCDR3) lengths. However, only in PRRSV-infected isolator piglets was nearly the identical spectratype observed for all lymphoid tissues. This result suggests dissemination of the same dominant B cell clones throughout the body. B cell expansion in PRRS was not associated with preferential VH gene usage or repertoire diversification and these cells appeared to bear a naive phenotype. The B cell population observed during infection comprised those with hydrophobic HCDR3s, especially sequences encoded by reading frame 3 of DHA that generates the AMVLV motif. Thus, the hydropathicity profile of B cells after infection was skewed to favor those with hydrophobic binding sites, whereas the normally dominant region of the hydropathicity profile containing neutral HCDR3s was absent. We believe that the hypergammaglobulinemia results from the products of these cells. We speculate that PRRSV infection generates a product that engages the BCR of naive B cells, displaying the AMVLV and similar motifs in HCDR3 and resulting in their T-independent proliferation without repertoire diversification.
The CD16+ Monocyte Subset Is More Permissive to Infection and Preferentially Harbors HIV-1 In Vivo
Authors: Ellery Philip J. , Tippett Emma , Chiu Ya-Lin , Paukovics Geza , Cameron Paul U. , Solomon Ajantha , Lewin Sharon R. , Gorry Paul R. , Jaworowski Anthony , Greene Warner C. , Sonza Secondo , Crowe Suzanne M.
Published: April 2014

HIV-1 persists in peripheral blood monocytes in individuals receiving highly active antiretroviral therapy (HAART) with viral suppression, despite these cells being poorly susceptible to infection in vitro. Because very few monocytes harbor HIV-1 in vivo, we considered whether a subset of monocytes might be more permissive to infection. We show that a minor CD16+ monocyte subset preferentially harbors HIV-1 in infected individuals on HAART when compared with the majority of monocytes (CD14highCD16−). We confirmed this by in vitro experiments showing that CD16+ monocytes were more susceptible to CCR5-using strains of HIV-1, a finding that is associated with higher CCR5 expression on these cells. CD16+ monocytes were also more permissive to infection with a vesicular stomatitis virus G protein-pseudotyped reporter strain of HIV-1 than the majority of monocytes, suggesting that they are better able to support HIV-1 replication after entry. Consistent with this observation, high molecular mass complexes of apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G (APOBEC3G) were observed in CD16+ monocytes that were similar to those observed in highly permissive T cells. In contrast, CD14highCD16− monocytes contained low molecular mass active APOBEC3G, suggesting this is a mechanism of resistance to HIV-1 infection in these cells. Collectively, these data show that CD16+ monocytes are preferentially susceptible to HIV-1 entry, more permissive for replication, and constitute a continuing source of viral persistence during HAART.
Recombinant gp120 Vaccine-Induced Antibodies Inhibit Clinical Strains of HIV-1 in the Presence of Fc Receptor-Bearing Effector Cells and Correlate Inversely with HIV Infection Rate
Authors: Forthal Donald N. , Gilbert Peter B. , Landucci Gary , Phan Tran
Published: April 2014

Nonneutralizing Abs may play a role in protecting animals and humans from lentiviral infections. We explored the Ab-dependent, cell-mediated virus inhibition (ADCVI) Ab response to recombinant gp120 (rgp120) vaccination in sera from 530 participants in the Vax 004 trial. Serum ADCVI activity was measured against a clinical R5 strain of HIV-1 using peripheral blood mononuclear effector cells from healthy donors. The level of vaccine-induced ADCVI activity correlated inversely with the rate of acquiring HIV infection following vaccination, such that for every 10% increase in ADCVI activity, there was a 6.3% decrease in the hazard rate of infection (p = 0.019). Some vaccinated individuals also mounted an ADCVI response against two other clinical R5 strains of HIV-1. However, ADCVI activity correlated poorly with neutralizing or CD4-gp120-blocking Ab activity measured against laboratory strains. Finally, the degree to which the ADCVI Ab response predicted the rate of infection was influenced by polymorphisms at the FcγRIIa and FcγRIIIa gene loci. These data indicate that rgp120 vaccination can elicit Abs with antiviral activity against clinical strains of HIV-1. However, such activity requires the presence of FcR-bearing effector cells. Our results provide further evidence that ADCVI may play a role in preventing HIV infection.
The CCL3 Family of Chemokines and Innate Immunity Cooperate In Vivo in the Eradication of an Established Lymphoma Xenograft by Rituximab
Authors: Cittera Elena , Leidi Marzia , Buracchi Chiara , Pasqualini Fabio , Sozzani Silvano , Vecchi Annunciata , Waterfield J. Douglas , Introna Martino , Golay Josée
Published: April 2014

The therapeutic mAb rituximab induced the expression of the CCL3 and CCL4 chemokines in the human lymphoma line BJAB following binding to the CD20 Ag. Induction of CCL3/4 in vitro was specific, was observed in several cell lines and freshly isolated lymphoma samples and also took place at the protein level in vitro and in vivo. To investigate the role of these β-chemokines in the mechanism of action of rituximab, we synthesized a N-terminally truncated CCL3 molecule CCL3(11–70), which had antagonist activity on chemotaxis mediated by either CCL3 or BJAB supernatant. We also set up an established s.c. BJAB tumor model in athymic mice. Rituximab, given weekly after tumors had reached 250 mm2, led to complete disappearance of the lymphoma within 2–3 wk. Treatment of mice with cobra venom factor showed that complement was required for rituximab therapeutic activity. Treatment of BJAB tumor bearing mice every 2 days with the CCL3(11–70) antagonist, starting 1 wk before rituximab treatment, had no effect on tumor growth by itself, but completely inhibited the therapeutic activity of the Ab. To determine whether CCL3 acts through recruitment/activation of immune cells, we specifically depleted NK cells, polymorphonuclear cells, and macrophages using mAbs, clodronate treatment, or Rag2−/−cγ−/− mice. The data demonstrated that these different cell populations are involved in BJAB tumor eradication. We propose that rituximab rapidly activates complement and induces β-chemokines in vivo, which in turn activate the innate immunity network required for efficient eradication of the bulky BJAB tumor.